0001558370-23-018837 | 10-Q | XBRL Viewer

Net Loss Per Share - Computation of Denominators Used in Net Loss per Share (Detail) - shares	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Basic:
Weighted average common shares outstanding - Basic	54,235,695	53,726,123	54,038,239	53,616,753
Diluted:
Weighted average common shares outstanding - Basic	54,235,695	53,726,123	54,038,239	53,616,753
Common stock equivalents			0
Denominator for diluted net loss per share	54,235,695	53,726,123	54,038,239	53,616,753

Income Taxes	9 Months Ended
Sep. 30, 2023
Income Taxes
Income Taxes	15. Income Taxes The Company has recognized a full tax valuation allowance against its deferred tax assets as of September 30, 2023 and December 31, 2022. The tax benefit related to the exercise of stock options is recognized as a deferred tax asset that is offset by a corresponding valuation allowance. As such, the Company’s effective tax rate is zero for each of the three and nine months ended September 30, 2023 and 2022. Historically, the Company’s benefit from income taxes related to state R&D tax credits exchanged for cash pursuant to the Connecticut R&D Tax Credit Exchange Program, which permits qualified small businesses engaged in R&D activities within Connecticut to exchange their unused R&D tax credits for a cash amount equal to 65% of the value of the exchanged credits. It was not eligible to exchange its R&D tax credit for cash during the three and nine months ended September 30, 2023 and 2022, therefore there was no benefit from income taxes for the three and nine months ended September 30, 2023 and 2022. As of September 30, 2023, the Company recorded $697 within income tax receivable which related to the 2020 R&D credit. The Inflation Reduction Act of 2022 included tax legislation that became effective early in 2023. Significant legislation for corporate taxpayers includes a corporate alternative minimum tax of 15.0% for companies with $1,000,000 or more in average net financial statement profits over the three previous years, as well as a 1.0% indirect excise tax on the repurchase of shares by a publicly traded company. The Company does not expect this legislation to have an effect on its tax provision as of September 30, 2023; however, the Company will continue to evaluate the effect on the tax provision each reporting period.

Stock-Based Compensation - Restricted Stock Unit Activity (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Jun. 01, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Number of Units
Outstanding, Beginning Balance
Outstanding, Ending Balance		775,711	640,950	775,711	640,950
Employees [Member] \| Restricted Stock Units [Member] \| General and Administrative [Member]
Number of Units
Compensation expense		$ 259	$ 381	$ 899	$ 2,350
2014 Equity Incentive Plan [Member] \| Non-employee Directors [Member] \| June 2023 \| Restricted Stock Units [Member]
Number of Units
Awarded	194,172
Outstanding, Ending Balance		194,172		194,172
Weighted Average Grant Date Fair Value
Weighted-average grant date fair value, awarded	$ 3.09
2014 Equity Incentive Plan [Member] \| Non-employee Directors [Member] \| June 2023 \| Restricted Stock Units [Member] \| General and Administrative [Member]
Number of Units
Compensation expense		$ 151		$ 199
2014 Equity Incentive Plan [Member] \| Employees And Non-Employee Members Of Board Of Directors [Member] \| Restricted Stock Units [Member]
Number of Units
Outstanding, Beginning Balance				372,513
Awarded				601,172
Vested and released				(194,389)
Forfeited				(3,585)
Outstanding, Ending Balance		775,711		775,711
Weighted Average Grant Date Fair Value
Weighted-average grant date fair value, outstanding, Beginning Balance				$ 13.20
Weighted-average grant date fair value, awarded				7.81
Weighted-average grant date fair value, vested and released				12.26
Weighted-average grant date fair value, forfeited				10.46
Weighted-average grant date fair value, outstanding, Ending Balance		$ 9.27		$ 9.27

Business - Additional Information (Detail) $ in Thousands	1 Months Ended		3 Months Ended						9 Months Ended
Business - Additional Information (Detail) $ in Thousands	Oct. 31, 2020	May 31, 2018	Sep. 30, 2023 USD ($) item	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Sep. 30, 2023 USD ($) item	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Nature Of Business [Line Items]
Date of formation									Jul. 02, 2004
Proceeds from equity and debt financing			$ 520,700						$ 520,700
Number of follow-on public offerings \| item			4						4
Payments received in connection with license and supply agreements			$ 284,800						$ 284,800
Unrestricted cash and cash equivalents and marketable securities			83,288						83,288
Accumulated deficit			652,408						652,408		$ 566,232
Net loss			(28,032)	$ (31,479)	$ (26,665)	$ (23,180)	$ (4,206)	$ (27,749)	(86,176)	$ (55,135)
Net cash used in operating activities									(74,708)	$ (55,220)
Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 2 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing		50.00%
License Agreement with Maruishi Pharmaceutical Co. Ltd [Member]
Nature Of Business [Line Items]
Earned milestone payment			$ 1,449						$ 1,449
Minimum [Member]
Nature Of Business [Line Items]
Expected approvals and commercial launches period									12 months
Maximum [Member]
Nature Of Business [Line Items]
Expected approvals and commercial launches period									18 months
CSL Vifor [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 1 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing	40.00%
Affiliated Entity [Member] \| Vifor International Ltd. [Member]
Nature Of Business [Line Items]
Proceeds from the sale of common stock under license agreement with Vifor International									$ 98,000
Affiliated Entity [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 2 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing		50.00%
Affiliated Entity [Member] \| CSL Vifor [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 1 [Member]
Nature Of Business [Line Items]
Percentage of net profit sharing	60.00%

Stock-Based Compensation - Summary of Assumptions Used in Black-Scholes Option Pricing Model (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	4.20%
Risk-free interest rate, minimum		2.65%	3.38%	1.70%
Risk-free interest rate, maximum		4.09%	4.22%	4.09%
Expected volatility	80.80%
Expected volatility, minimum		77.70%	76.30%	77.70%
Expected volatility, maximum		78.20%	81.30%	81.90%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Employee and Board of Directors Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected life of options (in years)	6 years 3 months	6 years 3 months	6 years 3 months	6 years 3 months

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Operating activities
Net loss	$ (86,176)	$ (55,135)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	10,129	13,933
Depreciation and amortization	177	187
Noncash lease expense	1,221	1,055
(Accretion)/amortization of available-for-sale marketable securities, net	(159)	498
Changes in operating assets and liabilities:
Accounts receivable, net - related party	(91)	(9,623)
Inventory, net	(883)	749
Other receivables	(1,186)	4
Prepaid expenses	3,609	(16,043)
Accounts payable and accrued expenses	37	10,455
Operating lease liabilities	(1,278)	(1,300)
Other	(108)
Net cash used in operating activities	(74,708)	(55,220)
Investing activities
Proceeds from maturities of available-for-sale marketable securities	118,590	162,185
Proceeds from redemptions of available-for-sale marketable securities, at par	4,000
Purchases of available-for-sale marketable securities	(48,601)	(77,858)
Purchases of property and equipment	(323)	(43)
Net cash provided by investing activities	73,666	84,284
Financing activities
Net proceeds from sales of common stock under open market sales agreement	1,117
Proceeds from the exercise of stock options	559	289
Net cash provided by financing activities	1,676	289
Net increase in cash, cash equivalents and restricted cash	634	29,353
Cash, cash equivalents and restricted cash at beginning of period	64,149	13,861
Cash, cash equivalents and restricted cash at end of period	64,783	$ 43,214
Noncash investing and financing activities
Accrual for leasehold improvements	$ 807

Stockholders' Equity

9 Months Ended

Sep. 30, 2023

Stockholders' Equity

Stockholders' Equity

10. Stockholders’ Equity

In August 2023, as a result of completion of the vesting period for restricted stock units granted in October 2022, an aggregate of 7,267 time-based restricted stock units vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In July 2023, as a result of completion of the quarterly vesting period for restricted stock units granted in October 2021, an aggregate of 8,875 time-based restricted stock units vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In June 2023, as a result of completion of the final vesting period for restricted stock units granted in December 2021, an aggregate of 26,199 time-based restricted stock units vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In June 2023, as a result of the completion of the one-year vesting period, an aggregate of 59,380 restricted stock units of members of the Board of Directors vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In April 2023, as a result of completion of the quarterly vesting period for restricted stock units granted in October 2021, an aggregate of 8,875 time-based restricted stock units vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In March 2023, as a result of the completion of the second year of the three-year vesting period for restricted stock units granted in March 2021, an aggregate of 15,999 time-based restricted stock units vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In February 2023, as a result of the completion of the first year of the three-year vesting period for restricted stock units granted in February 2022, an aggregate of 42,920 time-based restricted stock units vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

Also in February 2023, as a result of the completion of the third year of the three-year vesting period for restricted stock units granted in February 2020, an aggregate of 15,999 time-based restricted stock units vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In January 2023, as a result of completion of the quarterly vesting period for restricted stock units granted in October 2021, an aggregate 8,875 time-based restricted stock units vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In September 2022, as a result of the appointment of the Company’s new Chief Financial Officer, or CFO, 7,500 time-based restricted stock units held by the Company’s interim principal financial and accounting officer vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In June 2022, as a result of the accelerated vesting of restricted stock units associated with the former Chief Executive Officer’s, or CEO’s, modification of equity awards, an aggregate of 33,999 restricted stock units vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In June 2022, as a result of the completion of the one-year vesting period, an aggregate of 43,200 restricted stock units of members of the Board of Directors vested and were settled in shares of the Company’s common stock. Also in

June 2022, the Company granted 11,876 fully vested restricted stock units, which were immediately settled in shares of the Company’s common stock, to the Company’s chairman in consideration of his effort in connection with the Company’s CEO transition in 2021 (see Note 14, Stock-Based Compensation).

In March 2022, as a result of the achievement of certain performance targets, an aggregate of 37,999 performance-based restricted stock units of certain employees vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In March 2022, as a result of the completion of the first year of the three-year vesting period for restricted stock units granted in March 2021 and the full vesting of the second tranche of restricted stock units granted to the new Chief Executive Officer in October 2021, an aggregate of 39,278 time-based restricted stock units vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

In March 2022, the Company filed a universal shelf registration statement, or the Shelf Registration Statement, which provides for aggregate offerings of up to $300,000 of common stock, preferred stock, debt securities, warrants or any combination thereof. The Shelf Registration Statement was declared effective on May 11, 2022. The securities registered under the Shelf Registration Statement include $154,525 of unsold securities that had been registered under the Company’s previous Registration Statement on Form S-3 (File No. 333-230333) that was declared effective on April 4, 2019.

Also in March 2022, the Company entered into the Sales Agreement, pursuant to which it may, from time to time, issue and sell common stock with an aggregate value of up to $80,000 in an at-the-market offering. Jefferies is acting as sole sales agent for any sales made under the Sales Agreement for a 3% commission on gross proceeds. The common stock will be sold at prevailing market prices at the time of the sale, and, as a result, prices may vary. Unless otherwise terminated earlier, the Sales Agreement continues until all shares available under the Sales Agreement have been sold. During the three months ended September 30, 2023, 386,881 shares were sold under the Sales Agreement and the Company received net proceeds of $1,117.

The Company may offer additional securities under its Shelf Registration Statement from time to time in response to market conditions or other circumstances if it believes such a plan of financing is in the best interests of its stockholders.

In February 2022, as a result of the completion of the second year of the three-year vesting period for restricted stock units granted in February 2020, an aggregate of 32,666 time-based restricted stock units vested and were settled in shares of the Company’s common stock (see Note 14, Stock-Based Compensation).

- Definition

The entire disclosure for equity.

+ References

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+ Details

CONDENSED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Total
Balance, Value at Dec. 31, 2021	$ 53	$ 708,585	$ (480,758)	$ (358)	$ 227,522
Balance, Shares at Dec. 31, 2021	53,480,812
Stock-based compensation expense		4,266			4,266
Shares issued upon exercise of stock options, value		3			3
Shares issued upon exercise of stock options, shares	470
Shares issued upon vesting of restricted stock units, value		1,438			1,438
Shares issued upon vesting of restricted stock units, shares	109,943
Net loss			(27,749)		(27,749)
Other comprehensive income				(1,365)	(1,365)
Balance, Value at Mar. 31, 2022	$ 53	714,292	(508,507)	(1,723)	204,115
Balance, Shares at Mar. 31, 2022	53,591,225
Balance, Value at Dec. 31, 2021	$ 53	708,585	(480,758)	(358)	227,522
Balance, Shares at Dec. 31, 2021	53,480,812
Net loss					(55,135)
Other comprehensive income				(1,790)
Balance, Value at Sep. 30, 2022	$ 53	722,808	(535,893)	(2,148)	184,820
Balance, Shares at Sep. 30, 2022	53,733,607
Balance, Value at Mar. 31, 2022	$ 53	714,292	(508,507)	(1,723)	204,115
Balance, Shares at Mar. 31, 2022	53,591,225
Stock-based compensation expense		4,232			4,232
Shares issued upon exercise of stock options, value		182			182
Shares issued upon exercise of stock options, shares	30,000
Shares issued upon vesting of restricted stock units, value		423			423
Shares issued upon vesting of restricted stock units, shares	89,075
Net loss			(4,206)		(4,206)
Other comprehensive income				(324)	(324)
Balance, Value at Jun. 30, 2022	$ 53	719,129	(512,713)	(2,047)	204,422
Balance, Shares at Jun. 30, 2022	53,710,300
Stock-based compensation expense		3,520			3,520
Shares issued upon exercise of stock options, value		104			104
Shares issued upon exercise of stock options, shares	15,807
Shares issued upon vesting of restricted stock units, value		55			55
Shares issued upon vesting of restricted stock units, shares	7,500
Net loss			(23,180)		(23,180)
Other comprehensive income				(101)	(101)
Balance, Value at Sep. 30, 2022	$ 53	722,808	(535,893)	(2,148)	184,820
Balance, Shares at Sep. 30, 2022	53,733,607
Balance, Value at Dec. 31, 2022	$ 53	726,630	(566,232)	(1,672)	158,779
Balance, Shares at Dec. 31, 2022	53,797,341
Stock-based compensation expense		2,972			2,972
Shares issued upon exercise of stock options, value	$ 1	559			560
Shares issued upon exercise of stock options, shares	93,218
Shares issued upon vesting of restricted stock units, value		381			381
Shares issued upon vesting of restricted stock units, shares	83,793
Net loss			(26,665)		(26,665)
Other comprehensive income				571	571
Balance, Value at Mar. 31, 2023	$ 54	730,542	(592,897)	(1,101)	136,598
Balance, Shares at Mar. 31, 2023	53,974,352
Balance, Value at Dec. 31, 2022	$ 53	726,630	(566,232)	(1,672)	$ 158,779
Balance, Shares at Dec. 31, 2022	53,797,341
Shares issued upon exercise of stock options, shares					93,218
Net loss					$ (86,176)
Other comprehensive income				1,233
Balance, Value at Sep. 30, 2023	$ 54	738,435	(652,408)	(439)	85,642
Balance, Shares at Sep. 30, 2023	54,471,829
Balance, Value at Mar. 31, 2023	$ 54	730,542	(592,897)	(1,101)	136,598
Balance, Shares at Mar. 31, 2023	53,974,352
Stock-based compensation expense		3,116			3,116
Shares issued upon vesting of restricted stock units, value		326			326
Shares issued upon vesting of restricted stock units, shares	94,454
Net loss			(31,479)		(31,479)
Other comprehensive income				371	371
Balance, Value at Jun. 30, 2023	$ 54	733,984	(624,376)	(730)	108,932
Balance, Shares at Jun. 30, 2023	54,068,806
Net proceeds from sales of common stock under open market sales agreement		1,117			1,117
Net proceeds from sales of common stock under open market sales agreement (shares)	386,881
Stock-based compensation expense		3,171			3,171
Shares issued upon vesting of restricted stock units, value		163			163
Shares issued upon vesting of restricted stock units, shares	16,142
Net loss			(28,032)		(28,032)
Other comprehensive income				291	291
Balance, Value at Sep. 30, 2023	$ 54	$ 738,435	$ (652,408)	$ (439)	$ 85,642
Balance, Shares at Sep. 30, 2023	54,471,829

Business

9 Months Ended

Sep. 30, 2023

Business.

Business

1. Business

Cara Therapeutics, Inc., or the Company, is a commercial-stage biopharmaceutical corporation formed on July 2, 2004. The Company is leading a new treatment paradigm to improve the lives of patients suffering from pruritus. The Company’s primary activities to date have been organizing and staffing the Company, developing its lead product and product candidates, including conducting preclinical studies and clinical trials of difelikefalin-based product candidates, and raising capital.

In August 2021, the Company received U.S. Food and Drug Administration, or FDA, approval for KORSUVA®(difelikefalin) injection, or KORSUVA injection, for the treatment of moderate-to-severe pruritus associated with chronic kidney disease in adults undergoing hemodialysis. Commercial launch of KORSUVA injection began in the United States in April 2022 and the Company began recording the associated profit-sharing revenues in the second quarter of 2022.

In April 2022, the European Commission granted marketing authorization to difelikefalin injection under the brand name Kapruvia® (difelikefalin), or Kapruvia, for the treatment of moderate-to-severe pruritus associated with chronic kidney disease in adult hemodialysis patients. The marketing authorization approved Kapruvia for use in all member states of the European Union, or EU, as well as Iceland, Liechtenstein, and Norway. Kapruvia was also approved in the United Kingdom in April 2022. Commercial launches in Austria, Germany, Sweden, France, the Netherlands, and Finland have commenced. In August 2022, as part of the Access Consortium, difelikefalin injection was approved in Switzerland under the brand name Kapruvia, as well as Singapore and Canada under the brand name KORSUVA. Commercial launch in Switzerland has also commenced. In November 2022, difelikefalin injection was approved in the last Access Consortium country, Australia, under the brand name KORSUVA. Difelikefalin injection was also approved in the United Arab Emirates, Kuwait, Israel, and Japan under the brand name KORSUVA in January 2023, May 2023, June 2023, and September 2023, respectively. The Company expects additional approvals and commercial launches over the next 12-18 months. On November 1, 2023, the Company entered into a Purchase and Sale Agreement, or the HCR Agreement, with HCRX Investments Holdco, L.P. and Healthcare Royalty Partners IV, L.P., or collectively HCR, where HCR will receive future royalty payments for Kapruvia and KORSUVA (ex U.S. only) up to certain capped amounts in exchange for certain payments to the Company (see Note 18, Subsequent Event).

In 2018, the Company entered into a license and collaboration agreement with a joint venture between Vifor Pharma Group and Fresenius Medical Care Renal Pharmaceutical Ltd., or Vifor Fresenius Medical Care Renal Pharma Ltd., that provides full commercialization rights of Kapruvia, and where applicable KORSUVA, to Vifor Fresenius Medical Care Renal Pharma Ltd. worldwide (excluding the United States, Japan and South Korea). In markets outside of the United States, the Company is eligible to receive tiered double-digit royalty payments based on annual net sales, as defined in the agreement with Vifor Fresenius Medical Care Renal Pharma Ltd., of difelikefalin injection in the licensed territories. In the U.S. market, the agreement with Vifor Fresenius Medical Care Renal Pharma Ltd. provides that Vifor Fresenius Medical Care Renal Pharma Ltd. will promote difelikefalin injection in the dialysis clinics of Fresenius Medical Care North America, or FMCNA, under a profit-sharing arrangement, whereby the Company is generally entitled to 50% of the annual net profits (as defined in the agreement with Vifor Fresenius Medical Care Renal Pharma Ltd.) based on net FMCNA clinic sales (as defined in the agreement with Vifor Fresenius Medical Care Renal Pharma Ltd.) and Vifor Fresenius Medical Care Renal Pharma Ltd. is entitled to 50% of such net profits, subject to potential adjustments in a calendar year based on certain conditions (see Note 11, Collaboration and Licensing Agreements).

In 2020, the Company entered into a second licensing and collaboration agreement, along with stock purchase agreements, with Vifor (International) Ltd., or Vifor International, that provides full commercialization rights of KORSUVA injection to Vifor International in dialysis clinics in the United States under a profit-sharing arrangement, whereby total net sales of KORSUVA injection in the United States, as recorded by Vifor International, are reduced by

Vifor International’s cost of goods sold, or COGS, as well as a marketing and distribution fee owed by the Company based on the level of annual net sales, and the resulting amount is shared according to a 60% (Company)/40% (Vifor International) profit split (excluding sales to Fresenius Medical Center dialysis clinics, compensation for which is governed by the agreement with Vifor Fresenius Medical Care Renal Pharma Ltd.), subject to potential temporary adjustment in future years based on certain conditions (see Note 11, Collaboration and Licensing Agreements).

In May 2022, Vifor International assigned its rights and obligations under the license agreement and a supply agreement, as permitted under the agreements, to Vifor Fresenius Medical Care Renal Pharma Ltd. The Company’s rights and obligations under these agreements were unaffected by this assignment and the assignment did not affect the Company’s economic rights under the agreements with Vifor International.

In August 2022, Vifor Pharma Group (which includes Vifor International) was acquired by CSL Limited and subsequently renamed CSL Vifor as part of the acquisition. The acquisition of Vifor Pharma Group did not affect any of the Company’s rights and obligations pursuant to these agreements.

The Company also has a license agreement with Maruishi Pharmaceutical Co. Ltd., or Maruishi, under which the Company granted Maruishi an exclusive license to develop, manufacture, and commercialize drug products containing difelikefalin for acute pain and/or uremic pruritus in Japan. In September 2023, Maruishi received manufacturing and marketing approval from Japan’s Ministry of Health, Labour and Welfare for KORSUVA IV Injection Syringe for the treatment of pruritus in hemodialysis patients. In conjunction with the approval, the Company earned a $1,449 milestone payment per the terms of the licensing agreement (see Note 11, Collaboration and Licensing Agreements and Note 12, Revenue Recognition).

As of September 30, 2023, the Company had raised aggregate net proceeds of approximately $520,700 from several rounds of equity financing, including its initial public offering, or IPO, which closed in February 2014, four follow-on public offerings of common stock, which closed in July 2019, July 2018, April 2017 and August 2015, respectively, the issuance of common stock pursuant to its open market sales agreement with Jefferies LLC as sales agent, or the Sales Agreement, in 2023, and the issuance of convertible preferred stock and debt prior to the IPO. Including profit share revenue and royalties, the Company has also earned approximately $284,800 under its license and supply agreements for difelikefalin, primarily with CSL Vifor, Maruishi, and Chong Kun Dang Pharmaceutical Corp., or CKDP, and an earlier product candidate for which development efforts ceased in 2007. The Company has also received aggregate net proceeds of approximately $98,000 from the issuance and sale of the Company’s common stock to Vifor International in connection with the Company’s licensing agreement with CSL Vifor (see Note 11, Collaboration and Licensing Agreements).

As of September 30, 2023, the Company had unrestricted cash and cash equivalents and marketable securities of $83,288 and an accumulated deficit of $652,408. The Company has incurred substantial net losses and negative cash flows from operating activities in nearly every fiscal period since inception and expects this trend to continue for the foreseeable future. The Company recognized net losses of $28,032 and $23,180 for the three months ended September 30, 2023 and 2022, respectively, and $86,176 and $55,135 for the nine months ended September 30, 2023 and 2022, respectively, and had net cash used in operating activities of $74,708 and $55,220 for the nine months ended September 30, 2023 and 2022, respectively.

The Company is subject to risks common to other life science companies including, but not limited to, uncertainty of product development and commercialization, lack of marketing and sales history, development by its competitors of new technological innovations, dependence on key personnel, market acceptance of products, product liability, protection of proprietary technology, ability to raise additional financing, and compliance with FDA and other

government regulations. If the Company does not successfully commercialize KORSUVA injection, Kapruvia or any of its other product candidates, it will be unable to generate additional recurring product revenue or achieve profitability.

Commitments and Contingencies (Tables)

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies

Schedule of Other Information related to Stamford Lease and lease amendment


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows relating to operating leases	$	500		$	491		$	1,489		$	1,463
ROU assets obtained in exchange for new operating lease liabilities	$	6,779		$	—		$	6,779		$	—
Weighted average remaining lease term - operating leases (years)		10.4			1.3			10.4			1.3
Weighted average discount rate - operating leases		12.4	%		7.0	%		12.4	%		7.0	%

Schedule of Future Minimum Lease Payments under Non-cancellable Operating Leases, Reconciliation of Undiscounted Cash Flows to the Operating Lease Liabilities


Year Ending December 31,
2023 (Excluding the nine months ended September 30, 2023)	$	503
2024		108
2025		1,298
2026		1,330
2027		1,363
2028		1,398
Thereafter		8,874
Total future minimum lease payments, undiscounted		14,874
Less imputed interest		(7,562)
Total	$	7,312

Operating lease liabilities reported as of September 30, 2023:
Operating lease liabilities - current	$	497
Operating lease liabilities - non-current		6,815
Total	$	7,312

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 62,875	$ 63,741
Marketable securities	15,666	81,658
Accounts receivable, net - related party	3,351	3,260
Inventory, net	3,266	2,383
Income tax receivable	697	697
Other receivables	1,682	496
Prepaid expenses	12,658	16,267
Restricted cash	408	408
Total current assets	100,603	168,910
Operating lease right-of-use assets	7,108	1,551
Marketable securities, non-current	4,747	11,350
Property and equipment, net	1,380	426
Restricted cash, non-current	1,500
Total assets	115,338	182,237
Current liabilities:
Accounts payable and accrued expenses	22,384	21,540
Operating lease liabilities, current	497	1,918
Total current liabilities	22,881	23,458
Operating lease liabilities, non-current	6,815
Commitments and contingencies (Note 16)
Stockholders' equity:
Preferred stock; $0.001 par value; 5,000,000 shares authorized at September 30, 2023 and December 31, 2022, zero shares issued and outstanding at September 30, 2023 and December 31, 2022
Common stock; $0.001 par value; 100,000,000 shares authorized at September 30, 2023 and December 31, 2022, 54,471,829 shares and 53,797,341 shares issued and outstanding at September 30, 2023 and December 31, 2022, respectively	54	53
Additional paid-in capital	738,435	726,630
Accumulated deficit	(652,408)	(566,232)
Accumulated other comprehensive loss	(439)	(1,672)
Total stockholders' equity	85,642	158,779
Total liabilities and stockholders' equity	$ 115,338	$ 182,237

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2023

Net Loss Per Share

Computation of Denominators Used in Net Loss per Share

The denominators used in the net loss per share computations are as follows:


	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2023	2022	2023	2022
Basic:
Weighted average common shares outstanding	54,235,695	53,726,123	54,038,239	53,616,753
Diluted:
Weighted average common shares outstanding - Basic	54,235,695	53,726,123	54,038,239	53,616,753
Common stock equivalents*	—	—	—	—
Denominator for diluted net loss per share	54,235,695	53,726,123	54,038,239	53,616,753

*	No amounts were considered as their effects would be anti-dilutive.

Computation of Basic and Diluted Net Loss per Share

Basic and diluted net loss per share are computed as follows:


	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
Net loss - basic and diluted	$	(28,032)	$	(23,180)	$	(86,176)	$	(55,135)
Weighted-average common shares outstanding:
Basic and diluted		54,235,695		53,726,123		54,038,239		53,616,753
Net loss per share, basic and diluted:	$	(0.52)	$	(0.43)	$	(1.59)	$	(1.03)

Revenue Recognition - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Apr. 30, 2022	Jan. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Collaboration Arrangement [Line Items]
Accounts receivable, net - related party			$ 3,351		$ 3,351		$ 3,260
Total revenue			4,866	$ 10,813	17,964	$ 38,606
Other receivables			1,682		1,682		496
Commercial supply revenue
Collaboration Arrangement [Line Items]
Total revenue			1,252	3,370	5,843	8,160
License and milestone fees
Collaboration Arrangement [Line Items]
Total revenue			910		910	15,000
Royalty revenue
Collaboration Arrangement [Line Items]
Total revenue			167		415
Collaborative revenue
Collaboration Arrangement [Line Items]
Total revenue			2,471	7,443	10,631	15,446
Clinical compound revenue
Collaboration Arrangement [Line Items]
Total revenue			66		165
CSL Vifor, Maruishi and CKDP Agreements [Member]
Collaboration Arrangement [Line Items]
Other contract Assets			0		0		0
Other contract liabilities			0		0		$ 0
Maruishi Agreement [Member]
Collaboration Arrangement [Line Items]
Total revenue			1,449		1,449
Other receivables			1,449		1,449
Maruishi Agreement [Member] \| License and milestone fees
Collaboration Arrangement [Line Items]
Total revenue			910	0	910	0
Maruishi Agreement [Member] \| Collaborative revenue
Collaboration Arrangement [Line Items]
Total revenue			539	0	539	0
Maruishi Agreement [Member] \| Clinical compound revenue
Collaboration Arrangement [Line Items]
Total revenue			66	0	165	0
Affiliated Entity [Member] \| CSL Vifor Profit Sharing [Member] \| Collaborative revenue
Collaboration Arrangement [Line Items]
Total revenue			1,932	7,443	10,092	15,446
Affiliated Entity [Member] \| CSL Vifor Korsuva [Member] \| Commercial supply revenue
Collaboration Arrangement [Line Items]
Total revenue			1,252	3,370	5,843	8,160
Affiliated Entity [Member] \| CSL Vifor Korsuva [Member] \| Commercial Supply Revenue With No Associated Costs Of Goods Sold [Member]
Collaboration Arrangement [Line Items]
Total revenue		$ 2,295
Cost of goods sold		$ 0
Affiliated Entity [Member] \| CSL Vifor Korsuva [Member] \| Commercial Supply Revenue With Associated Costs Of Goods Sold [Member]
Collaboration Arrangement [Line Items]
Revenue						5,865
Cost of goods sold			1,558	3,055	5,566	5,136
Affiliated Entity [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 2 [Member] \| License and milestone fees \| Regulatory Milestones [Member]
Collaboration Arrangement [Line Items]
Proceeds from milestone payments	$ 15,000
Affiliated Entity [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd Agreement [Member] \| License and milestone fees
Collaboration Arrangement [Line Items]
Total revenue						15,000
Affiliated Entity [Member] \| CSL Vifor Kapruvia [Member] \| Royalty revenue
Collaboration Arrangement [Line Items]
Total revenue			$ 167	$ 0	$ 415	$ 0

Stock-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Thousands													1 Months Ended													3 Months Ended						9 Months Ended		12 Months Ended
	Jun. 15, 2023 shares	Jun. 01, 2023 $ / shares shares	Mar. 01, 2023 $ / shares shares	Oct. 12, 2022 $ / shares shares	Jun. 15, 2022 $ / shares shares	Jun. 02, 2022 $ / shares shares	Mar. 31, 2022 shares	Feb. 25, 2022 installment $ / shares shares	Dec. 17, 2021 installment $ / shares shares	Oct. 29, 2021 tranche $ / shares shares	Jun. 03, 2021 $ / shares shares	Mar. 30, 2021 installment $ / shares shares	Aug. 31, 2023 shares	Jul. 31, 2023 shares	Jun. 30, 2023 shares	Apr. 30, 2023 shares	Mar. 31, 2023 shares	Feb. 28, 2023 shares	Jan. 31, 2023 shares	Dec. 31, 2022 $ / shares shares	Oct. 31, 2022 shares	Jun. 30, 2022 shares	Mar. 31, 2022 shares	Feb. 28, 2022 shares	Feb. 29, 2020 installment $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares	Jun. 30, 2023 shares	Mar. 31, 2023 shares	Sep. 30, 2022 USD ($) $ / shares shares	Jun. 30, 2022 shares	Mar. 31, 2022 shares	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($) $ / shares shares	Dec. 31, 2015 shares	Jan. 01, 2023 shares	Nov. 20, 2019 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, par value \| $ / shares																				$ 0.001						$ 0.001						$ 0.001
Common stock, shares outstanding																				53,797,341						54,471,829						54,471,829
Common stock, shares issued																				53,797,341						54,471,829						54,471,829
Number of restricted stock units outstanding																										775,711			640,950			775,711	640,950
Number of options outstanding																				7,689,449						8,040,891			7,654,523			8,040,891	7,654,523
Options granted																																1,954,668
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares issued																										386,881
Restricted stock units vested shares																										16,142	94,454	83,793	7,500	89,075	109,943
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Payment Arrangement, Forfeited																3,585
Board of Directors Chairman [Member] \| Restricted Stock Units [Member] \| June 2022 \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units vested shares																						11,876
Employees [Member] \| Restricted Stock Units [Member] \| Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																										$ 90			$ 200			$ 385	$ 565
Employees [Member] \| Restricted Stock Units [Member] \| General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																										259			381			899	2,350
Director [Member] \| Restricted Stock Units [Member] \| General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																										$ 151			$ 126			$ 409	$ 503
Director [Member] \| Time-based Restricted Stock Units [Member] \| June 2022 \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted															1 year							1 year
Restricted stock units vested shares															59,380							43,200
Executive Officers [Member] \| Time-based Restricted Stock Units [Member] \| February 2022 \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted																		3 years
Restricted stock units vested shares																		42,920
Executive Officers [Member] \| Time-based Restricted Stock Units [Member] \| December 2021 \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units vested shares															26,199
Executive Officers [Member] \| Time-based Restricted Stock Units [Member] \| October 2022 \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units vested shares													7,267
Executive Officers [Member] \| Time-based Restricted Stock Units [Member] \| March 2021 \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted																												3 years
Restricted stock units vested shares																												15,999
Executive Officers [Member] \| Time-based Restricted Stock Units [Member] \| February 2020 \| Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted																		3 years						3 years
Restricted stock units vested shares																		15,999						32,666
Non-employee Consultants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options granted																										0			0			0	0
Employees And Non-Employee Members Of Board Of Directors [Member] \| Share-based Payment Arrangement, Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of options granted \| $ / shares																										$ 2.24			$ 7.37			$ 5.86	$ 7.27
2019 Inducement Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, par value \| $ / shares																																				$ 0.001
Awarded																										0			0			0	0
2019 Inducement Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares authorized																																				300,000
2019 Inducement Plan [Member] \| Share-based Payment Arrangement, Employee [Member] \| Share-Based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vested shares on first anniversary of grant date																																25.00%
2019 Inducement Plan [Member] \| Share-based Payment Arrangement, Employee [Member] \| Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted																																36 months
2019 Inducement Plan [Member] \| Share-based Payment Arrangement, Employee [Member] \| Share Based Compensation Subsequent Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted																																4 years
2014 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock options that may be granted after the tenth anniversary of the 2014 Plan																																0
Annual increases in number of shares reserved for issuance as a percentage of shares of capital stock outstanding through January 1, 2024																																		3.00%
Share-based compensation arrangement by share-based payment award, number of shares authorized																				10,589,103															12,203,023
Options granted																										155,747			437,500			1,954,668	1,739,919
2014 Equity Incentive Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of awards granted																																10 years
2014 Equity Incentive Plan [Member] \| Maximum [Member] \| Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation arrangement by share-based payment award, number of shares authorized																																		30,000,000
2014 Equity Incentive Plan [Member] \| Board of Directors Chairman [Member] \| Restricted Stock Units [Member] \| General and Administrative [Member] \| June 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																																	$ 100
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Performance Restricted Stock Units [Member] \| February 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded								243,000
Restricted stock units, grant date fair value \| $ / shares								$ 10.46
Compensation expense \| $																										$ 0			$ 0			$ 0	0
Number of restricted stock units outstanding																										0						0
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Performance Restricted Stock Units [Member] \| March 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded												176,000
Restricted stock units, grant date fair value \| $ / shares												$ 20.59
Compensation expense \| $																										$ 0			0			$ 0
Restricted stock units, vested																								37,999
Restricted stock units, forfeited due to performance targets not getting met																							93,999
Number of restricted stock units outstanding																										0						0
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Performance Restricted Stock Units [Member] \| March 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded			407,000
Restricted stock units, grant date fair value \| $ / shares			$ 10.06
Compensation expense \| $																										$ 0						$ 0
Number of restricted stock units outstanding																										407,000						407,000
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Performance Restricted Stock Units [Member] \| General and Administrative [Member] \| Modified November 2021 Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																																	303
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Performance Restricted Stock Units [Member] \| General and Administrative [Member] \| March 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																																	729
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| February 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted								3 years
Awarded								145,170
Restricted stock units, grant date fair value \| $ / shares								$ 10.46
Number of equal installment \| installment								3
Compensation expense \| $																										$ 103			116			$ 303	274
Restricted stock units, vested																		42,920
Number of restricted stock units outstanding																										78,665						78,665
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| December 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted									18 months
Awarded									63,573
Restricted stock units, grant date fair value \| $ / shares									$ 12.45
Number of equal installment \| installment									2
Compensation expense \| $																										$ 0			110			$ 199	323
Restricted stock units, vested	26,199																															0
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| March 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted												3 years
Awarded												100,000
Restricted stock units, grant date fair value \| $ / shares												$ 20.59
Number of equal installment \| installment												3
Compensation expense \| $																										83			83			$ 246	563
Restricted stock units, vested																						17,333	33,336									15,999
Restricted stock units, Forfeited																						17,333
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| February 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted																									3 years
Awarded																									98,000
Restricted stock units, grant date fair value \| $ / shares																									$ 16.36
Number of equal installment \| installment																									3
Compensation expense \| $																										0			66			$ 39	460
Restricted stock units, vested																								32,666								0
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| Research and Development [Member] \| February 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																										35			48			$ 100	113
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| Research and Development [Member] \| December 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																													53			96	157
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| Research and Development [Member] \| March 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																										55			55			164	164
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| Research and Development [Member] \| February 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																													44			26	131
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| General and Administrative [Member] \| Modified February 2020 Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																																	264
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| General and Administrative [Member] \| Modified November 2021 Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																																	317
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| General and Administrative [Member] \| February 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																										68			68			203	161
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| General and Administrative [Member] \| December 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																													57			103	166
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| General and Administrative [Member] \| March 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																										$ 28			28			82	399
2014 Equity Incentive Plan [Member] \| Employees [Member] \| Time-based Restricted Stock Units [Member] \| General and Administrative [Member] \| February 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																													22			$ 13	329
2014 Equity Incentive Plan [Member] \| Director [Member] \| Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted																																3 years
2014 Equity Incentive Plan [Member] \| Executive Officers [Member] \| Time-based Restricted Stock Units [Member] \| October 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded				7,267
Restricted stock units, grant date fair value \| $ / shares				$ 9.42
Number of restricted stock units outstanding																										0						0
2014 Equity Incentive Plan [Member] \| Executive Officers [Member] \| Time-based Restricted Stock Units [Member] \| March 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units, vested																	15,999
2014 Equity Incentive Plan [Member] \| Executive Officers [Member] \| Time-based Restricted Stock Units [Member] \| February 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units, vested																		15,999
2014 Equity Incentive Plan [Member] \| Executive Officers [Member] \| Time-based Restricted Stock Units [Member] \| General and Administrative [Member] \| October 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																										$ 13						$ 51
2014 Equity Incentive Plan [Member] \| Former Chief Financial Officer [Member] \| Performance Restricted Stock Units [Member] \| February 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units, Forfeited																						29,000
Restricted stock units, forfeited due to resignation of former CFO																						20,000
Restricted stock units, cancelled																				214,000
2014 Equity Incentive Plan [Member] \| Former Chief Financial Officer [Member] \| Time-based Restricted Stock Units [Member] \| December 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units, forfeited due to resignation of former CFO																						11,170
2014 Equity Incentive Plan [Member] \| Interim Principal Financial and Accounting Officer [Member] \| Time-based Restricted Stock Units [Member] \| June 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded					7,500
Restricted stock units, grant date fair value \| $ / shares					$ 7.94
Compensation expense \| $																													55				60
Restricted stock units, vested																																0
2014 Equity Incentive Plan [Member] \| Chief Executive Officer [Member] \| Time-based Restricted Stock Units [Member] \| October 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded										147,942
Restricted stock units, grant date fair value \| $ / shares										$ 16.83
Number of restricted stock unit tranches \| tranche										2
Restricted stock units, vested														8,875		8,875			8,875		35,500
Number of restricted stock units outstanding																										79,875						79,875
2014 Equity Incentive Plan [Member] \| Chief Executive Officer [Member] \| Time-based Restricted Stock Units [Member] \| General and Administrative [Member] \| October 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																										$ 150			151			$ 446	506
2014 Equity Incentive Plan [Member] \| Chief Executive Officer [Member] \| Share-Based Compensation Award, Tranche One [Member] \| Time-based Restricted Stock Units [Member] \| October 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vested shares on first anniversary of grant date										25.00%
Awarded										142,000
2014 Equity Incentive Plan [Member] \| Chief Executive Officer [Member] \| Share-based Compensation Award, Tranche Two [Member] \| Time-based Restricted Stock Units [Member] \| October 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted										36 months
Restricted stock units, vested							5,942
2014 Equity Incentive Plan [Member] \| Employee And Nonemployee Consultants [Member] \| Share-Based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of vested shares on first anniversary of grant date																																25.00%
2014 Equity Incentive Plan [Member] \| Employee And Nonemployee Consultants [Member] \| Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted																																36 months
2014 Equity Incentive Plan [Member] \| Employee And Nonemployee Consultants [Member] \| Share Based Compensation Subsequent Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted																																4 years
2014 Equity Incentive Plan [Member] \| Non-employee Directors [Member] \| Restricted Stock Units [Member] \| June 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded						59,380
Restricted stock units, grant date fair value \| $ / shares						$ 8.42
Compensation expense \| $																										$ 0
Number of restricted stock units outstanding																										0						0
2014 Equity Incentive Plan [Member] \| Non-employee Directors [Member] \| Restricted Stock Units [Member] \| June 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted											1 year
Awarded											43,200
Restricted stock units, grant date fair value \| $ / shares											$ 13.06
Compensation expense \| $																													0
Number of restricted stock units outstanding																										0						0
2014 Equity Incentive Plan [Member] \| Non-employee Directors [Member] \| Restricted Stock Units [Member] \| June 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of awards granted		1 year
Awarded		194,172
Restricted stock units, grant date fair value \| $ / shares		$ 3.09
Number of restricted stock units outstanding																										194,172						194,172
2014 Equity Incentive Plan [Member] \| Non-employee Directors [Member] \| Restricted Stock Units [Member] \| General and Administrative [Member] \| June 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																													$ 126			$ 209	164
2014 Equity Incentive Plan [Member] \| Non-employee Directors [Member] \| Restricted Stock Units [Member] \| General and Administrative [Member] \| June 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																																	$ 239
2014 Equity Incentive Plan [Member] \| Non-employee Directors [Member] \| Restricted Stock Units [Member] \| General and Administrative [Member] \| June 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense \| $																										$ 151						$ 199
2014 Equity Incentive Plan [Member] \| Employees And Non-Employee Members Of Board Of Directors [Member] \| Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Awarded																																601,172
Restricted stock units, grant date fair value \| $ / shares																																$ 7.81
Restricted stock units, vested																																194,389
Restricted stock units, Forfeited																																3,585
Number of restricted stock units outstanding																				372,513						775,711						775,711

Commitments and Contingencies - Additional Information (Detail) $ in Thousands			1 Months Ended		3 Months Ended		9 Months Ended
	Jul. 28, 2023 USD ($)	May 11, 2023 USD ($)	Jul. 31, 2021	Jul. 31, 2019 agreement	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Other Commitments [Line Items]
Operating lease liabilities					$ 7,312		$ 7,312
Operating lease right-of-use assets					7,108		7,108		$ 1,551
New Corporate Headquarters Office Space [Member]
Other Commitments [Line Items]
Lease, annual fixed rent		$ 1,300
Lease, fixed rent, annual increase, percent		2.50%
Option to extend		true
Operating Lease, renewable term		5 years
Operating lease liabilities	$ 6,672
Discount rate - operating leases		12.83%
Lessee, operating lease, incentives	2,900
Operating lease right-of-use assets	$ 6,779
Operating Lease, expense					214		214
New Corporate Headquarters Office Space [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Other Commitments [Line Items]
Lessee, operating lease, discount rate, basis spread on variable rate		7.75%
Lessee, operating lease, discount rate, variable rate basis, floor		2.75%
New Corporate Headquarters Office Space [Member] \| Research and Development [Member]
Other Commitments [Line Items]
Operating Lease, expense					150		150
New Corporate Headquarters Office Space [Member] \| General and Administrative [Member]
Other Commitments [Line Items]
Operating Lease, expense					64		64
Stamford Operating Lease [Member]
Other Commitments [Line Items]
Operating lease cost					407	$ 406	1,220	$ 1,218
Stamford Operating Lease [Member] \| Research and Development [Member]
Other Commitments [Line Items]
Operating lease cost					285	284	854	853
Stamford Operating Lease [Member] \| General and Administrative [Member]
Other Commitments [Line Items]
Operating lease cost					122	122	366	365
Non-Exclusive License Agreement \| Enteris Biopharma, Inc. [Member]
Other Commitments [Line Items]
Payment of milestone payment					$ 0	$ 5,000	$ 0	$ 5,000
Patheon MSA [Member] \| Patheon and Patheon Manufacturing Services LLC [Member]
Other Commitments [Line Items]
Number of related product agreements \| agreement				2
API Commercial Supply Agreement - PPL [Member]
Other Commitments [Line Items]
Agreement renewal term			5 years

Fair Value Measurements

9 Months Ended

Sep. 30, 2023

Fair Value Measurements

Fair Value Measurements

5. Fair Value Measurements

As of September 30, 2023 and December 31, 2022, the Company’s financial instruments consisted of cash, cash equivalents, available-for-sale marketable securities, accounts receivable, net – related party, prepaid expenses, restricted cash, accounts payable and accrued liabilities. The fair values of cash, cash equivalents, accounts receivable, net – related party, prepaid expenses, restricted cash, accounts payable and accrued liabilities approximate their carrying values due to the short-term nature of these financial instruments. Available-for-sale marketable securities are reported at their fair values, based upon pricing of securities with the same or similar investment characteristics as provided by third-party pricing services.

The Company validates the prices provided by its third-party pricing services by reviewing their pricing methods, obtaining market values from other pricing sources, and comparing them to the share prices presented by the third-party pricing services. After completing its validation procedures, the Company did not adjust or override any fair value measurements provided by its third-party pricing services as of September 30, 2023 or December 31, 2022.

The following tables summarize the Company’s financial assets measured at fair value on a recurring basis as of September 30, 2023 and December 31, 2022.

Fair value measurement as of September 30, 2023:


			Quoted prices in		Significant other		Significant
Financial assets			active markets for		observable		unobservable
			identical assets		inputs		inputs
Type of Instrument	Total		(Level 1)		(Level 2)		(Level 3)
Cash and cash equivalents:
Money market funds and checking accounts	$	62,875	$	62,875	$	—	$	—
Available-for-sale marketable securities:
U.S. government agency obligations		9,103		—		9,103		—
Corporate bonds		9,285		—		9,285		—
Municipal bonds		2,025		—		2,025		—
Restricted cash:
Commercial money market account		1,908		1,908		—		—
Total financial assets	$	85,196	$	64,783	$	20,413	$	—

Fair value measurement as of December 31, 2022:


			Quoted prices in		Significant other		Significant
Financial assets			active markets for		observable		unobservable
			identical assets		inputs		inputs
Type of Instrument	Total		(Level 1)		(Level 2)		(Level 3)
Cash and cash equivalents:
Money market funds and checking accounts	$	63,741	$	63,741	$	—	$	—
Available-for-sale marketable securities:
U.S. government agency obligations		8,877		—		8,877		—
Corporate bonds		35,185		—		35,185		—
Commercial paper		26,875		—		26,875		—
Municipal bonds		22,071		—		22,071		—
Restricted cash:
Commercial money market account		408		408		—		—
Total financial assets	$	157,157	$	64,149	$	93,008	$	—

There were no purchases, sales or maturities of Level 3 financial assets and no unrealized gains or losses related to Level 3 available-for-sale marketable securities during each of the three and nine months ended September 30, 2023 and 2022. There were no transfers of financial assets into or out of Level 3 classification during each of the three and nine months ended September 30, 2023 and 2022.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Accumulated Other Comprehensive Loss - Summary of Changes in Accumulated Other Comprehensive (Loss) Income, Net of Tax, from Unrealized Gains (Losses) on Available-for-Sale Marketable Securities (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Loss [Line Items]
Balance, Value	$ 108,932	$ 136,598	$ 158,779	$ 204,422	$ 204,115	$ 227,522	$ 158,779	$ 227,522
Amount reclassified from accumulated other comprehensive loss	0			0			0	0
Net current period other comprehensive income (loss)	291	371	571	(101)	(324)	(1,365)
Balance, Value	85,642	108,932	136,598	184,820	204,422	204,115	85,642	184,820
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Loss [Line Items]
Balance, Value	(730)	(1,101)	(1,672)	(2,047)	(1,723)	(358)	(1,672)	(358)
Other comprehensive income (loss) before reclassifications							1,233	(1,790)
Net current period other comprehensive income (loss)	291	371	571	(101)	(324)	(1,365)	1,233	(1,790)
Balance, Value	$ (439)	$ (730)	$ (1,101)	$ (2,148)	$ (2,047)	$ (1,723)	$ (439)	$ (2,148)

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

Amount after tax and reclassification adjustments of other comprehensive income (loss).

+ References

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Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

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+ Details

Collaboration and Licensing Agreements

9 Months Ended

Sep. 30, 2023

Collaboration and Licensing Agreements.

Collaboration and Licensing Agreements

11. Collaboration and Licensing Agreements

Vifor (International) Ltd. (Vifor International)

In October 2020, the Company entered into a license agreement with Vifor International, or Vifor Agreement No. 1, under which the Company granted Vifor International an exclusive license solely in the United States to use, distribute, offer for sale, promote, sell and otherwise commercialize difelikefalin injection for all therapeutic uses relating to the inhibition, prevention or treatment of itch associated with pruritus in hemodialysis and peritoneal dialysis patients in the United States. Under Vifor Agreement No. 1, the Company retains all rights with respect to the clinical development of, and activities to gain regulatory approvals of, difelikefalin injection in the United States.

After the assignment of rights of Vifor Agreement No. 1 from Vifor International to Vifor Fresenius Medical Care Renal Pharma Ltd. in May 2022, Vifor Agreement No. 1 provides full commercialization rights in dialysis clinics to

CSL Vifor in the United States under a profit-sharing arrangement. Pursuant to the profit-sharing arrangement, the Company is generally entitled to 60% of the net profits (as defined in Vifor Agreement No. 1) from sales of difelikefalin injection in the United States and CSL Vifor is entitled to 40% of such net profits (excluding sales to Fresenius Medical Center dialysis clinics, compensation for which is governed by Vifor Agreement No. 2, as defined below), subject to potential temporary adjustment in future years based on certain conditions. Under Vifor Agreement No. 1, in consideration of CSL Vifor’s conduct of the marketing, promotion, selling and distribution of difelikefalin injection in the United States, the Company pays a marketing and distribution fee to CSL Vifor based on the level of annual net sales. This fee as well as CSL Vifor’s COGS are deducted from net sales in calculating the net profits that are subject to the profit-sharing arrangement under Vifor Agreement No. 1.

In addition, pursuant to Vifor Agreement No. 1, the Company is eligible to receive payments of up to $240,000 upon the achievement of certain sales-based milestones.

The Company retains the rights to make and have made difelikefalin injection, or the Licensed Product, on a non-exclusive basis, in the United States for commercial sale of the Licensed Product for use in all therapeutic areas to prevent, inhibit or treat itch associated with pruritus in hemodialysis and peritoneal-dialysis patients, or the Field, anywhere in the world and for supply of Licensed Product to CSL Vifor under the terms of a supply agreement, or the Vifor International Supply Agreement, which was executed in September 2021. The supply price is the Company’s COGS, as calculated under GAAP, plus an agreed upon margin. The Vifor International Supply Agreement will co-terminate with Vifor Agreement No. 1. The Company also retains the rights to import, distribute, promote, sell and otherwise commercialize the Licensed Product on an exclusive basis outside of the Field either in or outside of the United States.

The Vifor International Supply Agreement is accounted for as a customer option that is not a material right because the selling price of the Licensed Product under the Vifor International Supply Agreement is the Company’s COGS plus an agreed upon margin, which is commensurate with the “COGS plus” model that the Company would charge other parties under similar agreements (the standalone selling price) and not at a discount. Therefore, the sale of commercial supply to CSL Vifor is not a performance obligation under Vifor Agreement No. 1 but rather the Vifor International Supply Agreement is a separate agreement from Vifor Agreement No. 1. The only performance obligation under the Vifor International Supply Agreement is the delivery of the Licensed Product to CSL Vifor for commercialization.

Vifor Fresenius Medical Care Renal Pharma Ltd.

In May 2018, the Company entered into a license agreement with Vifor Fresenius Medical Care Renal Pharma Ltd., or Vifor Agreement No. 2, under which the Company granted Vifor Fresenius Medical Care Renal Pharma Ltd. an exclusive, royalty-bearing license, or the Vifor License, to seek regulatory approval to commercialize, import, export, use, distribute, offer for sale, promote, sell and otherwise commercialize the Licensed Product in the Field worldwide (excluding the United States, Japan and South Korea), or the Territory.

The Company is eligible to receive from Vifor Fresenius Medical Care Renal Pharma Ltd. additional commercial milestone payments in the aggregate of up to $440,000, all of which are sales related. The Company is also eligible to receive tiered double-digit royalty payments based on annual net sales, as defined in Vifor Agreement No. 2, of difelikefalin injection in the licensed territories. The Company retained full commercialization rights for difelikefalin injection for the treatment of chronic kidney disease associated pruritus in the United States except in the dialysis clinics of FMCNA, where Vifor Fresenius Medical Care Renal Pharma Ltd. will promote difelikefalin injection under a profit-sharing arrangement (as defined in Vifor Agreement No. 2), based on net FMCNA clinic sales (as defined in Vifor Agreement No. 2) and the Company and Vifor Fresenius Medical Care Renal Pharma Ltd. are each entitled to 50% of such net profits, subject to potential adjustments in a calendar year based on certain conditions.

The Company retains the rights to make and have made the Licensed Product in the Territory for commercial sale by Vifor Fresenius Medical Care Renal Pharma Ltd. in the Field in or outside the Territory and for supply of Licensed Product to Vifor Fresenius Medical Care Renal Pharma Ltd. under the terms of a supply agreement, or the Vifor Supply Agreement, which was executed in May 2020. The supply price is the Company’s COGS, as calculated under GAAP, plus an agreed upon margin. The Vifor Supply Agreement will co-terminate with Vifor Agreement No. 2.

The Vifor Supply Agreement is accounted for as a customer option that is not a material right because the selling price of the Licensed Product under the Vifor Supply Agreement is the Company’s COGS plus an agreed upon margin, which is commensurate with the “COGS plus” model that the Company would charge other parties under similar agreements (the standalone selling price) and not at a discount. Therefore, the sale of compound to Vifor Fresenius Medical Care Renal Pharma Ltd. is not a performance obligation under Vifor Agreement No. 2 but rather the Vifor Supply Agreement is a separate agreement from Vifor Agreement No. 2. The only performance obligation under the Vifor Supply Agreement is the delivery of the Licensed Product to Vifor Fresenius Medical Care Renal Pharma Ltd. for commercialization.

Maruishi Pharmaceutical Co., Ltd. (Maruishi)

In April 2013, the Company entered into a license agreement with Maruishi, or the Maruishi Agreement, under which the Company granted Maruishi an exclusive license to develop, manufacture, and commercialize drug products containing difelikefalin for acute pain and/or uremic pruritus in Japan. Maruishi has the right to grant sub-licenses in Japan, which entitles the Company to receive sub-license fees, net of prior payments made by Maruishi to the Company. Under the Maruishi Agreement, the Company and Maruishi are required to use commercially reasonable efforts, at their own expense, to develop, obtain regulatory approval for and commercialize difelikefalin in the United States and Japan, respectively. In addition, the Company provided Maruishi specific clinical development services for difelikefalin used in Maruishi’s field of use.

Under the terms of the Maruishi Agreement, the Company is eligible to receive milestone payments upon the achievement of defined clinical and regulatory events as well as tiered, low double-digit royalties with respect to any sales of the licensed product sold in Japan by Maruishi, if any, and share in any sub-license fees.

In September 2022, Maruishi submitted a New Drug Application in Japan for approval of difelikefalin injection for the treatment of pruritus in hemodialysis patients. In September 2023, Maruishi received manufacturing and marketing approval from Japan’s Ministry of Health, Labour and Welfare for KORSUVA IV Injection Syringe for the treatment of pruritus in hemodialysis patients. In conjunction with the approval, the Company earned a $1,449 milestone payment per the terms of the licensing agreement (see Note 12, Revenue Recognition).

Chong Kun Dang Pharmaceutical Corporation (CKDP)

In April 2012, the Company entered into a license agreement with CKDP, or the CKDP Agreement, in South Korea, under which the Company granted CKDP an exclusive license to develop, manufacture and commercialize drug products containing difelikefalin in South Korea. The Company and CKDP are each required to use commercially reasonable efforts, at their respective expense, to develop, obtain regulatory approval for and commercialize difelikefalin in the United States and South Korea, respectively.

Under the terms of the CKDP Agreement, the Company is eligible to receive milestone payments upon the achievement of defined clinical and regulatory events as well as tiered royalties, with percentages ranging from the high single digits to the high teens, based on net sales of products containing difelikefalin in South Korea, if any, and share in any sub-license fees.

Available-for-Sale Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2023

Available-for-Sale Marketable Securities

Summary of Available-for-Sale Marketable Securities by Major Type of Security

As of September 30, 2023


			Gross Unrealized				Estimated Fair
Type of Security	Amortized Cost		Gains		Losses		Value
U.S. government agency obligations	$	9,500	$	—	$	(397)	$	9,103
Corporate bonds		9,327		—		(42)		9,285
Municipal bonds		2,025		—		—		2,025
Total available-for-sale marketable securities	$	20,852	$	—	$	(439)	$	20,413

As of December 31, 2022


			Gross Unrealized				Estimated Fair
Type of Security	Amortized Cost		Gains		Losses		Value
U.S. government agency obligations	$	9,500	$	—	$	(623)	$	8,877
Corporate bonds		35,828		—		(643)		35,185
Commercial paper		26,879		2		(6)		26,875
Municipal bonds		22,473		—		(402)		22,071
Total available-for-sale marketable securities	$	94,680	$	2	$	(1,674)	$	93,008

Schedule of Fair Values and Continuous Unrealized Loss Positions of Available-for-Sale Marketable Securities

As of September 30, 2023


	Less than 12 Months				12 Months or Greater				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
U.S. government agency obligations	$	—	$	—	$	9,103	$	(397)	$	9,103	$	(397)
Corporate bonds		1,826		—		7,459		(42)		9,285		(42)
Total	$	1,826	$	—	$	16,562	$	(439)	$	18,388	$	(439)

As of December 31, 2022


	Less than 12 Months				12 Months or Greater				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
U.S. government agency obligations	$	—	$	—	$	8,877	$	(623)	$	8,877	$	(623)
Corporate bonds		1,470		(26)		33,715		(617)		35,185		(643)
Commercial paper		15,906		(6)		—		—		15,906		(6)
Municipal bonds		982		(16)		19,589		(386)		20,571		(402)
Total	$	18,358	$	(48)	$	62,181	$	(1,626)	$	80,539	$	(1,674)

Schedule of Amortized Cost and Fair Values of Marketable Debt Securities by Contractual Maturity


	As of September 30, 2023				As of December 31, 2022
Contractual maturity	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Less than one year	$	15,852	$	15,666	$	82,678	$	81,658
One year to two years		5,000		4,747		12,002		11,350
Total	$	20,852	$	20,413	$	94,680	$	93,008

Revenue Recognition (Tables)

9 Months Ended

Sep. 30, 2023

Revenue Recognition

Schedule of disaggregation of revenue


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Collaborative revenue
CSL Vifor (KORSUVA injection profit sharing)	$	1,932	$	7,443	$	10,092	$	15,446
Maruishi		539		—		539		—
Total collaborative revenue	$	2,471	$	7,443	$	10,631	$	15,446
Commercial supply revenue
CSL Vifor* (KORSUVA injection)	$	1,252	$	3,370	$	5,843	$	8,160
Total commercial supply revenue	$	1,252	$	3,370	$	5,843	$	8,160
Royalty revenue
CSL Vifor (Kapruvia ex U.S.)	$	167	$	—	$	415	$	—
Total royalty revenue	$	167	$	—	$	415	$	—
License and milestone fees
Vifor Fresenius Medical Care Renal Pharma Ltd.	$	—	$	—	$	—	$	15,000
Maruishi		910		—		910		—
Total license and milestone fees	$	910	$	—	$	910	$	15,000
Clinical compound revenue
Maruishi	$	66	$	—	$	165	$	—
Total clinical compound revenue	$	66	$	—	$	165	$	—

_____________________________

* Includes amounts earned from Vifor International prior to Vifor International’s assignment of its rights and obligations to Vifor Fresenius Medical Care Renal Pharma Ltd. in May 2022.

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2023

Summary of Assumptions Used in Black-Scholes Option Pricing Model


	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2023	2022	2023	2022
Risk-free interest rate	4.20%	2.65% - 4.09%	3.38% - 4.22%	1.70% - 4.09%
Expected volatility	80.8%	77.7% - 78.2%	76.3% - 81.3%	77.7% - 81.9%
Expected dividend yield	0%	0%	0%	0%
Expected life of employee and Board options (in years)	6.25	6.25	6.25	6.25

Summary of Compensation Expense Relating to Stock Options


	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
Research and development	$	1,387	$	1,719	$	4,314	$	5,380
General and administrative		1,447		1,149		4,122		5,137
Total stock option expense	$	2,834	$	2,868	$	8,436	$	10,517

Summary of Stock Option Activity


		Weighted
	Number of	Average Exercise
	Shares	Price
Outstanding, December 31, 2022	7,689,449	$	14.35
Granted	1,954,668		8.31
Exercised	(93,218)		6.00
Forfeited	(177,085)		11.19
Expired	(1,332,923)		14.48
Outstanding, September 30, 2023	8,040,891	$	13.03
Options exercisable, September 30, 2023	4,583,227

Employees And Non-Employee Members Of Board Of Directors [Member]

Summary of Restricted Stock Unit Activity


		Weighted
	Number of	Average Grant
	Units	Date Fair Value
Outstanding, December 31, 2022	372,513	$	13.20
Awarded	601,172		7.81
Vested and released	(194,389)		12.26
Forfeited	(3,585)		10.46
Outstanding, September 30, 2023	775,711	$	9.27
Restricted stock units exercisable (vested and deferred), September 30, 2023	—

Stock-Based Compensation

9 Months Ended

Sep. 30, 2023

Stock-Based Compensation

Stock-Based Compensation

14. Stock-Based Compensation

2019 Inducement Plan

In October 2019, the Company’s Board of Directors adopted the 2019 Inducement Plan, or the 2019 Plan, which is a non-stockholder approved stock plan adopted pursuant to the “inducement exception” provided under Nasdaq Listing Rule 5635(c)(4), or Rule 5635, for the purpose of awarding (i) non-statutory stock options, (ii) restricted stock awards, (iii) restricted stock unit awards, (iv) other stock awards (collectively, the Inducement Awards) to new employees of the Company, as inducement material to such new employees entering into employment with the Company. In November 2019, the Company filed a Registration Statement on Form S-8 with the SEC covering the offering of up to 300,000 shares of its common stock, par value $0.001, pursuant to the Company’s 2019 Plan. Initial grants of Inducement Awards made to employees vest as to 25% on the first anniversary of the date of grant and the balance ratably over the next 36 months and subsequent grants vest monthly over a period of four years from the grant date.

2014 Equity Incentive Plan

The Company’s 2014 Equity Incentive Plan, or the 2014 Plan, is administered by the Company’s Board of Directors or a duly authorized committee thereof, referred to as the Plan administrator. The 2014 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock unit awards, stock appreciation rights, performance stock awards and other forms of equity compensation, collectively referred to as Stock Awards. Additionally, the 2014 Plan provides for the grant of performance cash awards. Incentive stock options may be granted only to employees. All other awards may be granted to employees, including officers, non-employee directors, and consultants. No incentive stock options may be granted under the 2014 Plan after the tenth anniversary of the effective date of the 2014 Plan. Stock Awards granted under the 2014 Plan vest at the rate specified by the Plan administrator. Initial grants of Stock Awards made to employees and non-employee consultants generally vest as to 25% on the first anniversary of the date of grant and the balance ratably over the next 36 months and subsequent grants vest monthly over a period of four years from the grant date. Stock options initially granted to members of the Company’s Board of Directors generally vest over a period of three years in equal quarterly installments from the date of the grant, subject to the option holder’s continued service as a director through such date. Subsequent grants to directors that are made automatically at Annual Meetings of Stockholders vest fully on the earlier of the first anniversary of the date of grant and the next Annual Meeting of Stockholders. The Plan administrator determines the term of Stock Awards granted under the 2014 Plan up to a maximum of ten years.

The aggregate number of shares of the Company’s common stock reserved for issuance under the 2014 Plan has automatically increased on January 1 of each year, beginning on January 1, 2015 and will continue to increase on January 1 of each year through and including January 1, 2024, by 3% of the total number of shares of the Company’s capital stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares determined by the Company’s Board of Directors. On January 1, 2023, the aggregate number of shares of common stock that may be issued pursuant to Stock Awards under the 2014 Plan automatically increased from 10,589,103 to 12,203,023. The maximum number of shares that may be issued pursuant to the exercise of incentive stock options under the 2014 Plan is 30,000,000 shares.

Restricted Stock Units

Pursuant to the Company’s non-employee director compensation policy, an aggregate of 194,172 restricted stock units were granted to non-employee directors on June 1, 2023, the date of the Company’s 2023 Annual Meeting of Stockholders, under the 2014 Plan with a grant date fair value of $3.09 per share. The restricted stock units will vest on the earlier of (i) June 1, 2024 and (ii) immediately prior to the Company’s next Annual Meeting of Stockholders

following the grant date, subject to the recipient’s continued service through such date. As a result, the Company recognizes compensation expense associated with these restricted stock units ratably over the one-year vesting period following the grant date. For the three and nine months ended September 30, 2023, stock compensation expense associated with these awards of $151 and $199, respectively, was recognized in general and administrative expense, or G&A expense. As of September 30, 2023, 194,172 restricted stock units were outstanding and available to vest and settle in shares of the Company’s common stock.

On March 1, 2023, the Compensation Committee of the Company’s Board of Directors, or the Compensation Committee, approved and granted a total of 407,000 restricted stock units to certain employees under the 2014 Plan with a grant date fair value of $10.06 per share. Vesting of the restricted stock units is contingent on the achievement of certain performance targets, subject to the recipient’s continuous service through each performance target. Recognition of compensation expense associated with these awards begins when, and to the extent, the performance criteria are probable of achievement and the employee has met the service conditions. For each of the three and nine months ended September 30, 2023, no stock compensation expense relating to these restricted stock units was recognized. As of September 30, 2023, 407,000 restricted stock units were outstanding and available to vest and settle in shares of the Company’s common stock.

On October 12, 2022, the Compensation Committee approved and granted a total of 7,267 time-based restricted stock units under the 2014 Plan, with a grant date fair value of $9.42 per share, to an executive officer of the Company. The restricted stock unit grant fully vested on August 31, 2023. For the three and nine months ended September 30, 2023, the Company recognized $13 and $51, respectively, of stock compensation expense associated with these awards, all of which was recorded within G&A expense. As of September 30, 2023, none of these restricted stock units were outstanding as these restricted stock units vested fully in August 2023.

On June 15, 2022, the Compensation Committee approved and granted a total of 7,500 time-based restricted stock units to the Company’s interim principal financial officer and principal accounting officer, as a result of his assuming the responsibilities of the Company’s former Chief Financial Officer on an interim basis, under the 2014 Plan with a grant date fair value of $7.94 per share. As a result, the Company recognized compensation expense associated with these restricted stock units ratably over the vesting period following the grant date. For the three and nine months ended September 30, 2022, the Company recognized $55 and $60, respectively, of stock compensation expense associated with these awards, all of which were recorded within G&A expense. As of September 30, 2023, none of these restricted stock units were outstanding as these restricted stock units vested fully in September 2022.

Pursuant to the Company’s non-employee director compensation policy, an aggregate of 59,380 restricted stock units were granted to non-employee directors on June 2, 2022, the date of the Company’s 2022 Annual Meeting of Stockholders, under the 2014 Plan with a grant date fair value of $8.42 per share. These restricted stock unit grants fully vested on June 2, 2023. For the nine months ended September 30, 2023, stock compensation expense associated with these awards of $209 was recognized in G&A expense. There was no stock compensation expense associated with these restricted stock units during the three months ended September 30, 2023. For the three and nine months ended September 30, 2022, stock compensation expense of $126 and $164, respectively, was recognized in G&A expense. As of September 30, 2023, none of these restricted stock units were outstanding as these restricted stock units vested fully on June 2, 2023. Also in June 2022, the Company granted 11,876 fully vested restricted stock units, which were immediately settled in shares of common stock, to the Company’s chairman in consideration of his effort in connection with the Company’s CEO transition in 2021. For the nine months ended September 30, 2022, stock compensation expense of $100 was recognized in G&A expense associated with this award.

On February 25, 2022, the Compensation Committee also approved and granted a total of 243,000 restricted stock units to certain employees under the 2014 Plan with a grant date fair value of $10.46 per share. Vesting of the restricted

stock units is contingent on the achievement of certain performance targets related to commercial milestones, subject to the recipient’s continuous service through each performance target. Recognition of compensation expense associated with these awards begins when, and to the extent, the performance criteria are probable of achievement and the employee has met the service conditions. For each of the three and nine months ended September 30, 2023 and 2022, no stock compensation expense relating to these restricted stock units was recognized. In June 2022, 29,000 of these restricted stock units were forfeited as a result of the resignation of our former CFO. In December 2022, 214,000 of these restricted stock units were cancelled as the performance targets associated with them were not achieved. As of September 30, 2023, none of these restricted stock units were outstanding as the remaining restricted stock units were cancelled in 2022.

Additionally, on February 25, 2022, the Compensation Committee also approved and granted a total of 145,170 time-based restricted stock units to certain employees under the 2014 Plan with a grant date fair value of $10.46 per share. The restricted stock units vest in three equal installments annually from the date of the grant. As a result, the Company recognizes compensation expense associated with these restricted stock units ratably over the three-year vesting period following the grant date. In April 2023, 3,585 of these restricted stock units were forfeited. In February 2023, 42,920 of these restricted stock units vested and were settled in shares of the Company’s common stock in satisfaction of the first year of vesting. For the three and nine months ended September 30, 2023, the Company recognized $103 and $303, respectively, of stock compensation expense associated with these awards, with $35 recorded in R&D expense and $68 recorded in G&A expense for the three months ended September 30, 2023, and $100 recorded in R&D expense and $203 recorded in G&A expense for the nine months ended September 30, 2023. For the three and nine months ended September 30, 2022, the Company recognized $116 and $274, respectively, of stock compensation expense associated with these awards, with $48 recorded in R&D expense and $68 recorded in G&A expense for the three months ended September 30, 2022, and $113 recorded in R&D expense and $161 recorded in G&A expense for the nine months ended September 30, 2022. In June 2022, 20,000 of these restricted stock units were forfeited as a result of the resignation of the Company’s former CFO. As of September 30, 2023, 78,665 restricted stock units were outstanding and available to vest and settle in shares of the Company’s common stock.

On December 17, 2021, the Compensation Committee approved and granted a total of 63,573 time-based restricted stock units to certain employees under the 2014 Plan with a grant date fair value of $12.45 per share. The restricted stock units vested in two equal installments on December 15, 2022 and June 15, 2023. As a result, the Company recognized compensation expense associated with these restricted stock units ratably over the 18-month vesting period following the grant date. On June 15, 2023, the remaining 26,199 of these restricted stock units fully vested and were settled in shares of the Company’s common stock. In June 2022, 11,170 of these restricted stock units were forfeited as a result of the resignation of the Company’s former CFO. For the nine months ended September 30, 2023, the Company recognized $199 of stock compensation expense associated with these awards, with $96 recorded in R&D expense and $103 recorded in G&A expense. There was no stock compensation expense recognized for these restricted stock awards for the three months ended September 30, 2023. For the three and nine months ended September 30, 2022, the Company recognized $110 and $323, respectively, of stock compensation expense associated with these awards, with $53 recorded in R&D expense and $57 recorded in G&A expense for the three months ended September 30, 2022, and $157 recorded in R&D expense and $166 recorded in G&A expense for the nine months ended September 30, 2022. As of September 30, 2023, none of these restricted stock units were outstanding as the remaining restricted stock units fully vested in June 2023.

On October 29, 2021, the Compensation Committee also approved and granted 147,942 time-based restricted stock units in connection with the appointment of the Company’s new CEO under the 2014 Plan with a grant date fair value of $16.83 per share. The first tranche of 142,000 restricted stock units vested 25% on the first anniversary of the date of grant and the balance vests quarterly over the next 36 months. As a result, 35,500 of these restricted stock units vested and were settled in shares of the Company’s common stock in October 2022. The second tranche of 5,942 restricted

stock units fully vested on March 31, 2022. As a result, the Company recognizes compensation expense associated with these two restricted stock unit tranches ratably over their respective vesting periods following the grant date. In July 2023, April 2023 and January 2023, 8,875 of these restricted stock units vested each period and were settled in shares of the Company’s common stock in satisfaction of the quarterly periods of vesting. For the three and nine months ended September 30, 2023, stock compensation expense associated with these awards of $150 and $446, respectively, was recognized in G&A expense. For the three and nine months ended September 30, 2022, stock compensation expense associated with these awards of $151 and $506, respectively, was recognized in G&A expense. As of September 30, 2023, 79,875 restricted stock units were outstanding and available to vest and settle in shares of the Company’s common stock.

Pursuant to the Company’s non-employee director compensation policy, an aggregate of 43,200 restricted stock units were granted to non-employee directors on June 3, 2021, the date of the Company’s 2021 Annual Meeting of Stockholders, under the 2014 Plan with a grant date fair value of $13.06 per share. The restricted stock units vested on June 3, 2022. As a result, the Company recognized compensation expense associated with these restricted stock units ratably over the one-year vesting period following the grant date. For the nine months ended September 30, 2022, stock compensation expense associated with these awards of $239 was recognized in G&A expense for these restricted stock units. There was no stock compensation expense recognized for the three months ended September 30, 2022. As of September 30, 2023, none of these restricted stock units were outstanding as the remaining restricted stock units fully vested in June 2022.

On March 30, 2021, the Compensation Committee approved and granted a total of 176,000 restricted stock units to certain employees under the 2014 Plan with a grant date fair value of $20.59 per share. Vesting of the restricted stock units was contingent on the achievement of certain performance targets related to clinical and regulatory milestones, subject to the recipient’s continuous service through each performance target. Recognition of compensation expense associated with these awards begins when, and to the extent, the performance criteria is probable of achievement and the employee has met the service conditions. In March 2022, 93,999 restricted stock units were forfeited as a result of not achieving certain defined performance targets of the awards. In February 2022, performance targets relating to 37,999 restricted stock units had been achieved and thus restricted stock units vested and the awards were settled in shares of common stock. For each of the three and nine months ended September 30, 2023, there was no stock compensation expense recognized as all of these restricted stock units either vested or were forfeited prior to these periods. For the nine months ended September 30, 2022, the Company recognized $729 of stock compensation expense associated with these awards in G&A expense. G&A amounts recorded for the nine months ended September 30, 2022 included $303 of stock compensation expense relating to the modification of certain of these restricted stock units on November 1, 2021 (see Stock Award Modifications below). There was no stock compensation expense recognized for the three months ended September 30, 2022. As of September 30, 2023, none of these restricted stock units were outstanding as the remaining restricted stock units either fully vested or were forfeited in prior periods.

Additionally on March 30, 2021, the Compensation Committee also approved and granted a total of 100,000 time-based restricted stock units to certain employees under the 2014 Plan with a grant date fair value of $20.59 per share. The restricted stock units vest in three equal installments annually from the date of the grant. As a result, the Company recognizes compensation expense associated with these restricted stock units ratably over the three-year vesting period following the grant date. In March 2023, 15,999 of these restricted stock units vested and were settled in shares of the Company’s common stock in satisfaction of the second year of vesting. In June 2022, 17,333 of these restricted stock units vested and were settled in shares of the Company’s common stock in accordance with the acceleration of vesting provisions relating to the modification of certain of these restricted stock units on November 1, 2021. In June 2022, 17,333 restricted stock units were forfeited as a result of the completion of the consulting agreement in relation to the modification of certain of these restricted stock units on November 1, 2021 (see Stock Award Modifications below). In March 2022, 33,336 of these restricted stock units vested and were settled in shares of the Company’s common stock in

satisfaction of the first year of vesting. For the three and nine months ended September 30, 2023, the Company recognized $83 and $246, respectively, of stock compensation expense associated with these awards, with $55 recorded in R&D expense and $28 in G&A expense for the three months ended September 30, 2023, and $164 recorded in R&D expense and $82 in G&A expense for the nine months ended September 30, 2023. For the three and nine months ended September 30, 2022, the Company recognized $83 and $563, respectively, of stock compensation expense associated with these awards, with $55 recorded in R&D expense and $28 in G&A expense for the three months ended September 30, 2022, and $164 recorded in R&D expense and $399 in G&A expense for the nine months ended September 30, 2022. G&A amounts recorded for the nine months ended September 30, 2022 included $317 of stock compensation expense relating to the modification of certain of these restricted stock units on November 1, 2021 (see Stock Award Modifications below). As of September 30, 2023, 15,999 restricted stock units were outstanding and available to vest and settle in shares of the Company’s common stock.

In February 2020, the Compensation Committee also approved and granted a total of 98,000 time-based restricted stock units to certain employees under the 2014 Plan with a grant date fair value of $16.36 per share. The restricted stock units vested in three equal installments annually from the date of the grant. As a result, the Company recognized compensation expense associated with these restricted stock units ratably over the three-year vesting period following the grant date. In February 2023, 15,999 of these restricted stock units vested and were settled in shares of the Company’s common stock in satisfaction of the third year of vesting. In February 2022, 32,666 of these restricted stock units vested and were settled in shares of the Company’s common stock in satisfaction of the second year of vesting. For the nine months ended September 30, 2023, the Company recognized $39 of stock compensation expense associated with these awards, with $26 recorded in R&D expense and $13 in G&A expense. There was no associated stock compensation expense for the three months ended September 30, 2023 as these restricted stock units were fully vested in the prior period. For the three and nine months ended September 30, 2022, the Company recognized $66 and $460, respectively, of stock compensation expense associated with these awards, with $44 recorded in R&D expense and $22 in G&A expense for the three months ended September 30, 2022, and $131 recorded in R&D expense and $329 in G&A expense for the nine months ended September 30, 2022. G&A amounts recorded for the nine months ended September 30, 2022 included $264 of stock compensation expense relating to the modification of certain of these restricted stock units on November 1, 2021 (see Stock Award Modifications below). As of September 30, 2023, none of these restricted stock units were outstanding as the remaining restricted stock units were fully vested in February 2023.

A summary of restricted stock unit activity related to employees and non-employee members of the Company’s Board of Directors as of and for the nine months ended September 30, 2023 is presented below:


		Weighted
	Number of	Average Grant
	Units	Date Fair Value
Outstanding, December 31, 2022	372,513	$	13.20
Awarded	601,172		7.81
Vested and released	(194,389)		12.26
Forfeited	(3,585)		10.46
Outstanding, September 30, 2023	775,711	$	9.27
Restricted stock units exercisable (vested and deferred), September 30, 2023	—

Stock Options

Under the 2014 Plan, the Company granted 155,747 and 437,500 stock options during the three months ended September 30, 2023 and 2022, respectively, and 1,954,668 and 1,739,919 stock options during the nine months ended September 30, 2023 and 2022, respectively. No stock options were granted under the 2019 Inducement Plan during the three and nine months ended September 30, 2023 and 2022. The fair values of stock options granted during the three and nine months ended September 30, 2023 and 2022 were estimated as of the dates of grant using the Black-Scholes option pricing model with the following assumptions:


	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2023	2022	2023	2022
Risk-free interest rate	4.20%	2.65% - 4.09%	3.38% - 4.22%	1.70% - 4.09%
Expected volatility	80.8%	77.7% - 78.2%	76.3% - 81.3%	77.7% - 81.9%
Expected dividend yield	0%	0%	0%	0%
Expected life of employee and Board options (in years)	6.25	6.25	6.25	6.25

The weighted-average grant date fair value per share of options granted to employees and non-employee members of the Company’s Board of Directors for their Board service during the three months ended September 30, 2023 and 2022 was $2.24 and $7.37, respectively, and during the nine months ended September 30, 2023 and 2022 was $5.86 and $7.27, respectively. No options were granted to non-employee consultants during the three and nine months ended September 30, 2023 and 2022.

During the three and nine months ended September 30, 2023 and 2022, the Company recognized compensation expense relating to stock options as follows:


	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
Research and development	$	1,387	$	1,719	$	4,314	$	5,380
General and administrative		1,447		1,149		4,122		5,137
Total stock option expense	$	2,834	$	2,868	$	8,436	$	10,517

The following were excluded from the table above as they are not related to stock options: compensation expense for (i) the vesting of certain employees’ restricted stock units for $90 in R&D expense and $259 in G&A expense for the three months ended September 30, 2023, and $385 in R&D expense and $899 in G&A expense for the nine months ended September 30, 2023; (ii) the vesting of certain employees’ restricted stock units for $200 in R&D expense and $381 in G&A expense for the three months ended September 30, 2022, and $565 in R&D expense and $2,350 in G&A expense for the nine months ended September 30, 2022; (iii) compensation expense relating to the Board of Directors’ restricted stock units for $151 and $409 in G&A expense for the three and nine months ended September 30, 2023, respectively; and (iv) compensation expense relating to the Board of Directors’ restricted stock units for $126 and $503 in G&A expense for the three and nine months ended September 30, 2022, respectively.

A summary of stock option award activity related to employees, non-employee members of the Company’s Board of Directors and non-employee consultants as of and for the nine months ended September 30, 2023 is presented below:


		Weighted
	Number of	Average Exercise
	Shares	Price
Outstanding, December 31, 2022	7,689,449	$	14.35
Granted	1,954,668		8.31
Exercised	(93,218)		6.00
Forfeited	(177,085)		11.19
Expired	(1,332,923)		14.48
Outstanding, September 30, 2023	8,040,891	$	13.03
Options exercisable, September 30, 2023	4,583,227

The Company does not expect to realize any tax benefits from its stock option activity or the recognition of stock-based compensation expense because the Company currently has net operating losses and has a full valuation allowance against its deferred tax assets. Accordingly, no amounts related to excess tax benefits have been reported in cash flows from operations for the nine months ended September 30, 2023 and 2022.

Stock Award Modifications

In November 2021, the Company and the former President and CEO mutually agreed to a transition from CEO to a consulting role through June 30, 2022, if not terminated earlier per the terms of the consulting agreement. As a result, the Company modified the terms of its former CEO’s outstanding Stock Awards to (1) automatically vest any unvested stock options or time-based restricted stock units that would have vested in the twelve month period following the end of the consulting period if continuous service is achieved with the Company during such twelve-month period; (2) extend the period during which the vested stock options may be exercised through the earlier of (i) eighteen months following the separation date (November 8, 2021); or (ii) the original expiration date applicable to each of the stock options, unless terminated earlier in accordance with the 2014 Plan, if continuous service is achieved with the Company; and (3) extend the period in which performance-based vesting milestones for restricted stock units may be achieved through March 31, 2022, if continuous service is achieved with the Company. The consulting agreement ended on June 30, 2022.

The Company determined that vested Stock Awards which had modifications due to the extension of the exercise period were Type 1 modifications pursuant to Financial Accounting Standards Board Accounting Standards Codification 718, or ASC 718, because those Stock Awards would have vested before and after the modification. Acceleration of vesting for the Stock Awards that would have vested in the twelve-month period following the consulting term was determined to be a Type 3 modification requiring stock compensation expense pursuant to ASC 718 because absent the modification terms, those Stock Awards would have been forfeited as of the last day that the former CEO provided continuous service as a consultant. In addition, Type 4 performance-based restricted stock units were not considered probable of achieving performance targets on the modification date, but the vesting targets were achieved with respect to 17,333 performance-based restricted stock units in February 2022, which resulted in additional stock compensation expense being recorded through June 30, 2022.

During the nine months ended September 30, 2022, total incremental stock compensation expense relating to modifications of stock options, time-based and performance-based restricted stock units of the former CEO was $2,563, which was included in G&A expense for the nine months ended September 30, 2022. Of this total amount, $1,679 was included in G&A expense in the stock option compensation expense table above for the nine months ended September 30, 2022. There was no incremental stock compensation expense related to the modifications of stock options, time-

based and performance-based restricted stock units for the three months ended September 30, 2022, as a result of the consulting period ending on June 30, 2022.

Net Loss Per Share

9 Months Ended

Sep. 30, 2023

Net Loss Per Share

Net Loss Per Share

13. Net Loss Per Share

The Company computes basic net income (loss) per share by dividing net income (loss) by the weighted-average number of shares of common stock outstanding. Diluted net income (loss) per share includes the potential dilutive effect of common stock equivalents as if such securities were exercised during the period, when the effect is dilutive. Common stock equivalents may include outstanding stock options or restricted stock units, which are included using the treasury stock method when dilutive. For each of the three and nine months ended September 30, 2023 and 2022, the Company excluded the effects of potentially dilutive shares that were outstanding during those respective periods from the denominator as their inclusion would be anti-dilutive due to the Company’s net losses during those periods.

The denominators used in the net loss per share computations are as follows:


	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2023	2022	2023	2022
Basic:
Weighted average common shares outstanding	54,235,695	53,726,123	54,038,239	53,616,753
Diluted:
Weighted average common shares outstanding - Basic	54,235,695	53,726,123	54,038,239	53,616,753
Common stock equivalents*	—	—	—	—
Denominator for diluted net loss per share	54,235,695	53,726,123	54,038,239	53,616,753

*	No amounts were considered as their effects would be anti-dilutive.

Basic and diluted net loss per share are computed as follows:


	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2023		2022		2023		2022
Net loss - basic and diluted	$	(28,032)	$	(23,180)	$	(86,176)	$	(55,135)
Weighted-average common shares outstanding:
Basic and diluted		54,235,695		53,726,123		54,038,239		53,616,753
Net loss per share, basic and diluted:	$	(0.52)	$	(0.43)	$	(1.59)	$	(1.03)

As of September 30, 2023, 8,040,891 stock options and 775,711 restricted stock units were outstanding, which could potentially dilute basic earnings per share in the future, but were not included in the computation of diluted net loss per share because to do so would have been anti-dilutive as a result of the net loss for the period.

As of September 30, 2022, 7,654,523 stock options and 640,950 restricted stock units were outstanding, which could potentially dilute basic earnings per share in the future, but were not included in the computation of diluted net loss per share because to do so would have been anti-dilutive as a result of the net loss for the period.

Available-for-Sale Marketable Securities

9 Months Ended

Sep. 30, 2023

Available-for-Sale Marketable Securities

Available-for-Sale Marketable Securities

3. Available-for-Sale Marketable Securities

As of September 30, 2023 and December 31, 2022, the Company’s available-for-sale marketable securities consisted of debt securities issued by U.S. government-sponsored entities and investment grade institutions as well as municipal bonds.

The following tables summarize the Company’s available-for-sale marketable securities by major type of security as of September 30, 2023 and December 31, 2022:

As of September 30, 2023


			Gross Unrealized				Estimated Fair
Type of Security	Amortized Cost		Gains		Losses		Value
U.S. government agency obligations	$	9,500	$	—	$	(397)	$	9,103
Corporate bonds		9,327		—		(42)		9,285
Municipal bonds		2,025		—		—		2,025
Total available-for-sale marketable securities	$	20,852	$	—	$	(439)	$	20,413

As of December 31, 2022


			Gross Unrealized				Estimated Fair
Type of Security	Amortized Cost		Gains		Losses		Value
U.S. government agency obligations	$	9,500	$	—	$	(623)	$	8,877
Corporate bonds		35,828		—		(643)		35,185
Commercial paper		26,879		2		(6)		26,875
Municipal bonds		22,473		—		(402)		22,071
Total available-for-sale marketable securities	$	94,680	$	2	$	(1,674)	$	93,008

The following tables summarize the fair value and gross unrealized losses of the Company’s available-for-sale marketable securities by investment category and disaggregated by the length of time that individual debt securities have been in a continuous unrealized loss position as of September 30, 2023 and December 31, 2022:

As of September 30, 2023


	Less than 12 Months				12 Months or Greater				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
U.S. government agency obligations	$	—	$	—	$	9,103	$	(397)	$	9,103	$	(397)
Corporate bonds		1,826		—		7,459		(42)		9,285		(42)
Total	$	1,826	$	—	$	16,562	$	(439)	$	18,388	$	(439)

As of December 31, 2022


	Less than 12 Months				12 Months or Greater				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
	Value		Losses		Value		Losses		Value		Losses
U.S. government agency obligations	$	—	$	—	$	8,877	$	(623)	$	8,877	$	(623)
Corporate bonds		1,470		(26)		33,715		(617)		35,185		(643)
Commercial paper		15,906		(6)		—		—		15,906		(6)
Municipal bonds		982		(16)		19,589		(386)		20,571		(402)
Total	$	18,358	$	(48)	$	62,181	$	(1,626)	$	80,539	$	(1,674)

As of September 30, 2023 and December 31, 2022, no allowance for credit losses were recognized on the Company’s available-for-sale debt securities as no portion of the unrealized losses associated with those securities were due to credit losses. The information that the Company considered in reaching the conclusion that an allowance for credit losses was not necessary is as follows:

As of September 30, 2023 and December 31, 2022, the Company held a total of 7 out of 9 positions and 35 out of 39 positions, respectively, that were in an unrealized loss position, 6 of which had been in an unrealized loss position for 12 months or greater as of September 30, 2023. Unrealized losses individually and in aggregate, including any in an unrealized loss position for 12 months or greater, were not considered to be material for each respective period. Based on the Company’s review of these securities, the Company believes that the cost basis of its available-for-sale marketable securities is recoverable.

U.S. government agency obligations. The unrealized losses on the Company’s investments in direct obligations of government agencies were due to changes in interest rates and non-credit related factors. The credit ratings of these investments in the Company’s portfolio have not been downgraded below investment grade status. The contractual terms of these investments do not permit the issuer to repay principal at a price less than the amortized cost bases of the investments, which is equivalent to the par value on the maturity date. The Company expects to recover the entire amortized cost bases of these securities on the maturity date. The Company does not intend to sell these investments, and it is not “more likely than not” that the Company will be required to sell these investments before recovery of their amortized cost bases. The Company held 3 out of 3 positions for its U.S. government agency obligations, that were in unrealized loss positions as of September 30, 2023.

Corporate bonds and municipal bonds. The unrealized losses on the Company’s investments in corporate bonds and municipal bonds were due to changes in interest rates and non-credit related factors. The credit ratings of these investments in the Company’s portfolio have not been downgraded below investment grade status. The contractual terms of these investments do not permit the issuer to repay principal at a price less than the amortized cost bases of the investments, which is equivalent to the par value on the maturity date. The Company expects to recover the entire amortized cost bases of these securities on the maturity date. The Company does not intend to sell these investments, and it is not “more likely than not” that the Company will be required to sell these investments before recovery of their amortized cost bases. The Company held 4 out of 4 positions for its corporate bonds, and 0 out of 2 positions for its municipal bonds, that were in unrealized loss positions as of September 30, 2023.

The Company classifies its marketable debt securities based on their contractual maturity dates. As of September 30, 2023, the Company’s marketable debt securities mature at various dates through November 2024. The amortized cost and fair values of marketable debt securities by contractual maturity were as follows:


	As of September 30, 2023				As of December 31, 2022
Contractual maturity	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Less than one year	$	15,852	$	15,666	$	82,678	$	81,658
One year to two years		5,000		4,747		12,002		11,350
Total	$	20,852	$	20,413	$	94,680	$	93,008

All available-for-sale marketable securities are classified as marketable securities, current or marketable securities, non-current depending on the contractual maturity date of the individual available-for-sale security. Other income, net includes interest and dividends, accretion/amortization of discounts/premiums, realized gains and losses on sales of securities and credit loss expense due to declines in the fair value of securities, if any. The cost of securities sold is based on the specific identification method.

There were no sales of available-for-sale marketable securities during each of the three and nine months ended September 30, 2023 and 2022.

As of September 30, 2023 and December 31, 2022, accrued interest receivables on the Company’s available-for-sale debt securities were $232 and $489, respectively, and were included within other receivables.

Net Loss Per Share - Computation of Basic and Diluted Net Loss per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Net Loss Per Share
Net loss - basic and diluted	$ (28,032)	$ (31,479)	$ (26,665)	$ (23,180)	$ (4,206)	$ (27,749)	$ (86,176)	$ (55,135)
Weighted-average common shares outstanding:
Basic	54,235,695			53,726,123			54,038,239	53,616,753
Diluted	54,235,695			53,726,123			54,038,239	53,616,753
Net loss per share:
Basic	$ (0.52)			$ (0.43)			$ (1.59)	$ (1.03)
Diluted	$ (0.52)			$ (0.43)			$ (1.59)	$ (1.03)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
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-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
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-URI https://asc.fasb.org//1943274/2147483443/250-10-50-3

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+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2023	Nov. 09, 2023
Document And Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-36279
Entity Registrant Name	CARA THERAPEUTICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	75-3175693
Entity Address, Address Line One	4 Stamford Plaza
Entity Address, Address Line Two	107 Elm Street
Entity Address, Address Line Three	9th Floor
Entity Address, City or Town	Stamford
Entity Address, State or Province	CT
Entity Address, Postal Zip Code	06902
City Area Code	203
Local Phone Number	406-3700
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	CARA
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		54,480,704
Entity Central Index Key	0001346830
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false

Related Party Transactions (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Related Party Transaction [Line Items]
Accounts due from related parties	$ 3,351		$ 3,351		$ 3,260
Revenue from contract with customer	4,866	$ 10,813	17,964	$ 38,606
Commercial supply revenue
Related Party Transaction [Line Items]
Revenue from contract with customer	1,252	3,370	5,843	8,160
Collaborative revenue
Related Party Transaction [Line Items]
Revenue from contract with customer	2,471	7,443	10,631	15,446
Royalty revenue
Related Party Transaction [Line Items]
Revenue from contract with customer	167		415
License and milestone fees
Related Party Transaction [Line Items]
Revenue from contract with customer	910		910	15,000
Affiliated Entity [Member] \| CSL Vifor Profit Sharing [Member] \| Collaborative revenue
Related Party Transaction [Line Items]
Revenue from contract with customer	1,932	7,443	10,092	15,446
Affiliated Entity [Member] \| CSL Vifor Kapruvia [Member] \| Royalty revenue
Related Party Transaction [Line Items]
Revenue from contract with customer	$ 167	0	$ 415	0
Affiliated Entity [Member] \| Vifor International Ltd. [Member]
Related Party Transaction [Line Items]
Shares owned as a result of upfront and milestone payments	7,396,770		7,396,770
Related party ownership percentage	13.60%		13.60%
Affiliated Entity [Member] \| CSL Vifor [Member]
Related Party Transaction [Line Items]
Accounts due from related parties	$ 3,351		$ 3,351		$ 3,260
Affiliated Entity [Member] \| CSL Vifor [Member] \| Commercial supply revenue
Related Party Transaction [Line Items]
Revenue from related parties	1,252	3,370	5,843	8,160
Related party cost of goods sold	1,558	3,055	5,566	5,136
Affiliated Entity [Member] \| CSL Vifor [Member] \| CSL Vifor Profit Sharing [Member] \| Collaborative revenue
Related Party Transaction [Line Items]
Revenue from contract with customer	1,932	$ 7,443	10,092	15,446
Affiliated Entity [Member] \| CSL Vifor [Member] \| CSL Vifor Kapruvia [Member] \| Royalty revenue
Related Party Transaction [Line Items]
Revenue from contract with customer	$ 167		$ 415
Affiliated Entity [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] \| Vifor Agreement No 2 [Member] \| License and milestone fees
Related Party Transaction [Line Items]
Revenue from related parties				$ 15,000

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2023

Fair Value Measurements

Summary of Financial Assets Measured at Fair Value on Recurring Basis

Fair value measurement as of September 30, 2023:


			Quoted prices in		Significant other		Significant
Financial assets			active markets for		observable		unobservable
			identical assets		inputs		inputs
Type of Instrument	Total		(Level 1)		(Level 2)		(Level 3)
Cash and cash equivalents:
Money market funds and checking accounts	$	62,875	$	62,875	$	—	$	—
Available-for-sale marketable securities:
U.S. government agency obligations		9,103		—		9,103		—
Corporate bonds		9,285		—		9,285		—
Municipal bonds		2,025		—		2,025		—
Restricted cash:
Commercial money market account		1,908		1,908		—		—
Total financial assets	$	85,196	$	64,783	$	20,413	$	—

Fair value measurement as of December 31, 2022:


			Quoted prices in		Significant other		Significant
Financial assets			active markets for		observable		unobservable
			identical assets		inputs		inputs
Type of Instrument	Total		(Level 1)		(Level 2)		(Level 3)
Cash and cash equivalents:
Money market funds and checking accounts	$	63,741	$	63,741	$	—	$	—
Available-for-sale marketable securities:
U.S. government agency obligations		8,877		—		8,877		—
Corporate bonds		35,185		—		35,185		—
Commercial paper		26,875		—		26,875		—
Municipal bonds		22,071		—		22,071		—
Restricted cash:
Commercial money market account		408		408		—		—
Total financial assets	$	157,157	$	64,149	$	93,008	$	—

Available-for-Sale Marketable Securities - Schedule of Fair Values and Continuous Unrealized Loss Positions of Available-for-Sale Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value	$ 1,826	$ 18,358
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses		(48)
Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Fair Value	16,562	62,181
Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Gross Unrealized Losses	(439)	(1,626)
Available-for-sale marketable securities, continuous unrealized loss position, Fair Value	18,388	80,539
Available-for-sale marketable securities, continuous unrealized loss position, Gross Unrealized Losses	(439)	(1,674)
U.S. Government Agency Obligations [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Fair Value	9,103	8,877
Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Gross Unrealized Losses	(397)	(623)
Available-for-sale marketable securities, continuous unrealized loss position, Fair Value	9,103	8,877
Available-for-sale marketable securities, continuous unrealized loss position, Gross Unrealized Losses	(397)	(623)
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value	1,826	1,470
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses		(26)
Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Fair Value	7,459	33,715
Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Gross Unrealized Losses	(42)	(617)
Available-for-sale marketable securities, continuous unrealized loss position, Fair Value	9,285	35,185
Available-for-sale marketable securities, continuous unrealized loss position, Gross Unrealized Losses	$ (42)	(643)
Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value		15,906
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses		(6)
Available-for-sale marketable securities, continuous unrealized loss position, Fair Value		15,906
Available-for-sale marketable securities, continuous unrealized loss position, Gross Unrealized Losses		(6)
Municipal Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Fair Value		982
Available-for-sale marketable securities, continuous unrealized loss position, Less than 12 Months, Gross Unrealized Losses		(16)
Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Fair Value		19,589
Available-for-sale marketable securities, continuous unrealized loss position, 12 Months or Greater, Gross Unrealized Losses		(386)
Available-for-sale marketable securities, continuous unrealized loss position, Fair Value		20,571
Available-for-sale marketable securities, continuous unrealized loss position, Gross Unrealized Losses		$ (402)

Revenue Recognition

9 Months Ended

Sep. 30, 2023

Revenue Recognition

Revenue Recognition

12. Revenue Recognition

The Company primarily recognizes revenue under its license and collaboration agreements from (1) collaborative revenue from its share of the profit generated by KORSUVA injection sales in the United States; (2) commercial supply revenue from the Company’s sales of commercial product to CSL Vifor, which is subsequently sold to wholesalers; (3) royalty revenue from net sales of Kapruvia in Europe; and (4) sales-based or regulatory milestone payments, which could be earned in the future in accordance with certain licensing agreements. As of September 30, 2023, the Company has not earned any sales-based milestones under its collaboration agreements.

As of September 30, 2023, the Company had license and collaboration agreements with CSL Vifor, Maruishi and CKDP. The following table provides amounts included in the Company’s Condensed Statements of Comprehensive Loss as revenue for the three and nine months ended September 30, 2023 and 2022, respectively:


	Three Months Ended September 30,				Nine Months Ended September 30,
	2023		2022		2023		2022
Collaborative revenue
CSL Vifor (KORSUVA injection profit sharing)	$	1,932	$	7,443	$	10,092	$	15,446
Maruishi		539		—		539		—
Total collaborative revenue	$	2,471	$	7,443	$	10,631	$	15,446
Commercial supply revenue
CSL Vifor* (KORSUVA injection)	$	1,252	$	3,370	$	5,843	$	8,160
Total commercial supply revenue	$	1,252	$	3,370	$	5,843	$	8,160
Royalty revenue
CSL Vifor (Kapruvia ex U.S.)	$	167	$	—	$	415	$	—
Total royalty revenue	$	167	$	—	$	415	$	—
License and milestone fees
Vifor Fresenius Medical Care Renal Pharma Ltd.	$	—	$	—	$	—	$	15,000
Maruishi		910		—		910		—
Total license and milestone fees	$	910	$	—	$	910	$	15,000
Clinical compound revenue
Maruishi	$	66	$	—	$	165	$	—
Total clinical compound revenue	$	66	$	—	$	165	$	—

_____________________________

* Includes amounts earned from Vifor International prior to Vifor International’s assignment of its rights and obligations to Vifor Fresenius Medical Care Renal Pharma Ltd. in May 2022.

Collaborative revenue

Beginning in April 2022, the Company began recording its share of the profit generated by KORSUVA injection sales by CSL Vifor to third parties in the United States. Under the license agreements with CSL Vifor, KORSUVA injection net sales are calculated by CSL Vifor which are net of discounts, rebates, and allowances. These amounts include the use of estimates and judgments, which could be adjusted based on actual results in the future. The Company records its share of the net profits from the sales of KORSUVA injection in the United States on a net basis (since the Company is not the primary obligor and does not retain inventory risk) and presents the revenue earned each period as

collaborative revenue. During the three and nine months ended September 30, 2023, the Company recorded $1,932 and $10,092, respectively, as collaborative revenue for its profit-share from the sales of KORSUVA injection in the United States. During the three and nine months ended September 30, 2022, the Company recorded $7,443 and $15,446, respectively, as collaborative revenue for its profit-share from the sales of KORSUVA injection in the United States.

The Company’s distinct performance obligations under the Maruishi Agreement include transfer of the license to the Company’s intellectual property, which allowed Maruishi to develop and commercialize difelikefalin, for acute pain and uremic pruritus indications in Japan, which occurred at inception of the contract in 2013 (considered license and milestone fees revenue), and performance of R&D services, which occurred from 2013 to 2015 (considered collaborative revenue), as those services were rendered. The Company agreed to conduct limited work on an oral tablet formulation of difelikefalin and to conduct Phase 1 and proof-of-concept Phase 2 clinical trials of an intravenous formulation of difelikefalin to be used to treat patients with uremic pruritus. The Company agreed to transfer the data and information from such development to Maruishi for its efforts to obtain regulatory approval in Japan. These activities are referred to as R&D services and are included as collaborative revenue.

During each of the three and nine months ended September 30, 2023, the criteria for revenue recognition for a regulatory milestone event set forth in the Maruishi Agreement was achieved, and the Company earned $1,449, of which $539 was recorded as collaborative revenue based on the relative standalone selling prices described at contract inception. This regulatory milestone payment was considered variable consideration due to the uncertainty of occurrence of this event as specified at inception of the agreement. Therefore, this potential regulatory milestone payment was not included in the transaction price at the inception of the agreement. There was no collaborative revenue recognized under the Maruishi Agreement during the three and nine months ended September 30, 2022.

Commercial supply revenue

Under the Vifor International Supply Agreement, the Company’s only performance obligation is the delivery of KORSUVA injection to CSL Vifor in accordance with the receipt of purchase orders. Revenue from the sale of commercial supply product to CSL Vifor is recognized as delivery of the product occurs. The Company had commercial supply revenue of $1,252 and $5,843 for the three and nine months ended September 30, 2023, respectively, with associated COGS of $1,558 and $5,566, respectively. The Company had commercial supply revenue of $3,370 for the three months ended September 30, 2022 with associated COGS of $3,055. The Company had commercial supply revenue of $8,160 for the nine months ended September 30, 2022, of which $2,295 was recognized in January 2022 with no associated COGS since these inventory costs were incurred prior to regulatory approval on August 23, 2021, and $5,865 was recognized with associated COGS of $5,136 since these inventory costs were capitalized as inventory subsequent to regulatory approval.

Royalty revenue

Royalty revenue includes amounts related to the Company’s royalties earned from CSL Vifor on the net sales of Kapruvia in Europe, based on the amount of net sales in a licensed territory during a calendar year. Sales-based royalty payments related to a license of IP are recognized as revenue when the respective sales occur, and the net sales tier is achieved. During the three and nine months ended September 30, 2023, the Company recorded $167 and $415, respectively, as royalty revenue based on net sales of Kapruvia. There was no royalty revenue for the three and nine months ended September 30, 2022.

License and milestone fees revenue

Under Vifor Agreement No. 2, the Company’s performance obligations of granting a license to allow Vifor Fresenius Medical Care Renal Pharma Ltd. to commercialize difelikefalin injection worldwide, except in the United States, Japan and South Korea, which occurred at inception of the contract in May 2018, and performing R&D services by the Company to obtain sufficient clinical data which were shared with Vifor Fresenius Medical Care Renal Pharma Ltd. to allow them to receive regulatory approval to sell difelikefalin in the licensed territory, were not distinct, and were accounted for as a single performance obligation during the period the that the R&D services were rendered (see Note 11, Collaboration and Licensing Agreements).

Revenue related to achievement of milestone events is recognized when the Company has determined that it is probable that a milestone event will be achieved and there will not be a significant reversal of revenue in future periods. Upon probability of achievement of a milestone event, the most likely amount of variable consideration is included in the transaction price. Subsequent changes to the transaction price, after contract initiation, are allocated to the performance obligations in the contract on the same basis as at contract inception. Revenue for variable consideration is recognized in the same manner (point in time or over time) as for the performance obligations to which the payment amounts were allocated.

During each of the three and nine months ended September 30, 2023, the criteria for revenue recognition for a regulatory milestone event set forth in the Maruishi Agreement was achieved and the Company earned $1,449, of which $910 was recorded as license and milestone fees revenue based on the relative standalone selling prices described at contract inception. This regulatory milestone payment was considered variable consideration due to the uncertainty of occurrence of this event as specified at inception of the agreement. Therefore, this potential regulatory milestone payment was not included in the transaction price at the inception of the agreement. There was no license and milestone fees revenue recognized under the Maruishi Agreement during the three and nine months ended September 30, 2022.

As a result of the European Commission’s regulatory approval of Kapruvia in April 2022, the Company achieved a $15,000 regulatory milestone payment from Vifor Fresenius Medical Care Renal Pharma Ltd. under Vifor Agreement No. 2, which was recorded as license and milestone fees revenue for the nine months ended September 30, 2022. This regulatory milestone payment was considered variable consideration due to the uncertainty of occurrence of this event as specified at inception of the agreement. Therefore, this potential regulatory milestone payment was not included in the transaction price at the inception of the agreement.

Clinical compound revenue

The Company’s only performance obligation under the supply agreement with Maruishi is to deliver clinical compound to Maruishi in accordance with the receipt of purchase orders. During the three and nine months ended September 30, 2023, the Company recognized clinical compound revenue of $66 and $165, respectively, from the sale of clinical compound to Maruishi. There were no sales of clinical compound during the three and nine months ended September 30, 2022.

Contract balances

As of September 30, 2023 and December 31, 2022, respectively, the Company recorded accounts receivable, net – related party of $3,351 and $3,260 which primarily related to its profit-sharing revenue from sales of KORSUVA injection in the United States by CSL Vifor, its commercial supply of KORSUVA injection to CSL Vifor, and royalty revenue from CSL Vifor relating to sales of Kapruvia outside of the United States. The Company also recorded $1,449 within other receivables for the regulatory milestone payment earned from Maruishi as of September 30, 2023. There

were no other contract assets or contract liabilities related to the CSL Vifor, Maruishi and CKDP agreements as of September 30, 2023 and December 31, 2022.

The Company routinely assesses the creditworthiness of its license and collaboration partners. The Company has not experienced any losses related to receivables from its license and collaboration partners as of September 30, 2023 and December 31, 2022.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-9

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-10

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-15

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-12

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-13

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org//606/tableOfContent

+ Details

Commitments and Contingencies

9 Months Ended

Sep. 30, 2023

Commitments and Contingencies

Commitments and Contingencies

16. Commitments and Contingencies

License Agreement with Enteris Biopharma, Inc.

In August 2019, the Company entered into a non-exclusive license agreement, or the Enteris License Agreement, with Enteris Biopharma, Inc., or Enteris, pursuant to which Enteris granted to the Company a non-exclusive, royalty-bearing license, including the right to grant sublicenses, under certain proprietary technology and patent rights related to or covering formulations for oral delivery of peptide active pharmaceutical ingredients with functional excipients to enhance permeability and/or solubility, known as Enteris’s Peptelligence^® technology, to develop, manufacture and commercialize products using such technology worldwide, excluding Japan and South Korea.

The Company is also obligated, pursuant to the Enteris License Agreement, to pay Enteris (1) milestone payments upon the achievement of certain development, regulatory and commercial milestones and (2) low-single digit royalty percentages on net sales of licensed products, subject to reductions in specified circumstances. During the three and nine months ended September 30, 2023, no milestone payments or royalties were paid to Enteris by the Company in relation to the Enteris License Agreement. During the three months ended September 30, 2022, Enteris earned a $5,000 milestone payment based on the first patient dosing in a Phase 3 trial, which was subsequently paid in October 2022. This milestone payment to Enteris was recorded in R&D expense for the three and nine months ended September 30, 2022.

Manufacturing Agreements

In July 2021, the Company entered into an API Commercial Supply Agreement with Polypeptide Laboratories S.A., or PPL, that defines each party’s responsibilities with respect to PPL’s manufacture and supply of the active pharmaceutical ingredient difelikefalin, or API, for the difelikefalin injection product candidate. Under the API Commercial Supply Agreement, PPL shall manufacture API at its facility for sale and supply to the Company, in the amounts as set forth in purchase orders to be provided by the Company. The Company will be required to purchase its requirements of API for each year of the term of the agreement, based on internal forecasts.

The API Commercial Supply Agreement will continue until the fifth anniversary of the approval by the FDA of the new drug application for KORSUVA injection, unless the API Commercial Supply Agreement is earlier terminated, and will automatically be extended for successive five-year periods unless either party gives notice to the other party of its intention to terminate.

In July 2019, the Company entered into a Master Manufacturing Services Agreement, or MSA, with Patheon UK Limited, or Patheon. The MSA governs the general terms under which Patheon, or one of its affiliates, will provide non-exclusive manufacturing services to the Company for the drug products specified by the Company from time to time. Pursuant to the MSA, the Company has agreed to order from Patheon at least a certain percentage of its commercial requirements for a product under a related Product Agreement. Each Product Agreement that the Company may enter into from time to time will be governed by the terms of the MSA, unless expressly modified in such Product Agreement.

In July 2019, the Company entered into two related Product Agreements under the MSA, one with each of Patheon and Patheon Manufacturing Services LLC, or Patheon Greenville, to govern the terms and conditions of the manufacture of commercial supplies of difelikefalin injection, the Company’s lead product candidate. Pursuant to the Product Agreements, Patheon and Patheon Greenville will manufacture commercial supplies of difelikefalin injection at the Monza, Italy and Greenville, North Carolina manufacturing sites, respectively, from active pharmaceutical ingredient supplied by the Company. Patheon and Patheon Greenville will be responsible for supplying the other required raw materials and packaging components, and will also provide supportive manufacturing services such as quality control testing for raw materials, packaging components and finished product.

Leases (Original Corporate Headquarters in 2015 & Amendment for Additional Space in 2020)

Lease expense is recognized on a straight-line basis over the lease term of the Company’s lease agreements for its original headquarters, and additional office space, in Stamford, Connecticut. As a result, $407 and $1,220 of operating lease cost, or lease expense, was recognized for the three and nine months ended September 30, 2023, respectively, consisting of $285 relating to R&D lease expense and $122 relating to G&A lease expense for the three months ended September 30, 2023, and $854 relating to R&D lease expense and $366 relating to G&A lease expense for the nine months ended September 30, 2023. For the three and nine months ended September 30, 2022, $406 and $1,218, respectively, of lease expense was recognized, consisting of $284 relating to R&D lease expense and $122 relating to G&A lease expense for the three months ended September 30, 2022, and $853 relating to R&D lease expense and $365 relating to G&A lease expense for the nine months ended September 30, 2022.

Lease (New Corporate Headquarters in May 2023)

On May 11, 2023, the Company entered into the New Lease for the Company’s new principal executive offices. The initial term of the New Lease commences on the earlier to occur of (a) the date the Company first occupies the premises for the regular conduct of its business therein, and (b) the date the Landlord delivers the premises to the Company in the condition required under the terms of the New Lease, provided that such date shall be no sooner than November 1, 2023,

or the Commencement Date, and will expire on the last day of the calendar month in which occurs the tenth anniversary of the Rent Commencement Date, as defined below, or the Term.

The annual fixed rent rate under the New Lease will initially be $1.3 million (considered by the Company to be at market rate as of the signing of the New Lease), commencing on the date which is the later to occur of (a) the date which is 12 months after the Commencement Date and (b) November 1, 2024, or the Rent Commencement Date, and will increase 2.5% annually thereafter. The Company expects to begin paying rent in November 2024.

The Company is also responsible for the payment of Additional Rent, as defined in the New Lease, including its share of the operating and tax expenses for the building. As a result, the New Lease contains both a lease (the right to use the asset) and a non-lease component (common area maintenance services) which are accounted for separately. The Company allocates the consideration to the lease and non-lease component on a relative standalone price basis.

The Company will have the option to extend the Term under the New Lease for an additional five years on the same terms and conditions (other than with respect to the annual fixed rent at the annual fair market rental rate, as defined in the New Lease) as set forth in the New Lease. This renewable term is not included as part of the lease term as defined in ASC 842 since it is not reasonably certain that the Company will exercise that option on the Commencement Date.

Since the New Lease does not provide an implicit interest rate, the Company used an incremental borrowing rate equal to the 3-month Secured Overnight Financing Rate, or SOFR, plus 7.75% per annum subject to a 3-month SOFR floor of 2.75%, which is based on the rate that the Company could obtain in the market for a fully collateralized loan equal to the term of the New Lease, or 12.83%.

On July 28, 2023, the Company recorded a lease liability and a right-of-use asset, or the ROU asset, for the New Lease since it obtained control of the premises to begin work on its leasehold improvements prior to the Commencement Date. The initial lease liability of $6,672 was recorded as the sum of the present value of the future minimum lease payments over the term of the lease. Lease incentives of $2,900 were not included within lease payments since the timing of these costs being incurred and reimbursed to the Company was uncertain, and they are neither paid nor payable as of July 28, 2023. These lease incentives will reduce the lease liability and ROU asset by the costs incurred once the Company actually incurs the costs and the amounts qualify for reimbursement. The reduction to the lease liability will be reversed once the Company is reimbursed for the qualified costs. The reduction to the ROU asset will be recognized prospectively over the remainder of the lease term. The ROU asset of $6,779 was initially recorded as the amount of the lease liability plus prepaid rent paid in May 2023. During the three months ended September 30, 2023, the Company did not incur any costs that qualified for reimbursement as a lease incentive.

Beginning on July 28, 2023 and during the entire term of the New Lease, interest expense is calculated using the effective interest method and the ROU asset (including prepaid rent) will be amortized on a straight-line basis over the lease term, and both will be recorded as lease expense. As a result, lease expense of $214 for the New Lease was recorded for each of the three and nine months ended September 30, 2023, consisting of $150 relating to R&D lease expense and $64 relating to G&A lease expense.

Other information related to the leases (both existing and new) was as follows:


	Three Months Ended September 30,						Nine Months Ended September 30,
	2023			2022			2023			2022
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash outflows relating to operating leases	$	500		$	491		$	1,489		$	1,463
ROU assets obtained in exchange for new operating lease liabilities	$	6,779		$	—		$	6,779		$	—
Weighted average remaining lease term - operating leases (years)		10.4			1.3			10.4			1.3
Weighted average discount rate - operating leases		12.4	%		7.0	%		12.4	%		7.0	%

Future minimum lease payments under non-cancellable operating leases, as well as a reconciliation of these undiscounted cash flows to the operating lease liabilities as of September 30, 2023, were as follows:


Year Ending December 31,
2023 (Excluding the nine months ended September 30, 2023)	$	503
2024		108
2025		1,298
2026		1,330
2027		1,363
2028		1,398
Thereafter		8,874
Total future minimum lease payments, undiscounted		14,874
Less imputed interest		(7,562)
Total	$	7,312

Operating lease liabilities reported as of September 30, 2023:
Operating lease liabilities - current	$	497
Operating lease liabilities - non-current		6,815
Total	$	7,312

Stockholders' Equity - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended												3 Months Ended						9 Months Ended
	Aug. 31, 2023	Jul. 31, 2023	Jun. 30, 2023	Apr. 30, 2023	Mar. 31, 2023	Feb. 28, 2023	Jan. 31, 2023	Oct. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Feb. 28, 2022	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Dec. 31, 2022
Sale Of Stock [Line Items]
Common stock, shares issued													54,471,829						54,471,829	53,797,341
Proceeds from the sale of common stock																			$ 1,117
Unsold Securities Under Shelf Registration Statement dated April 4, 2019 [Member]
Sale Of Stock [Line Items]
Aggregate offering price of securities											$ 154,525							$ 154,525
Open Market Sales Agreement [Member] \| Jeffries LLC [Member]
Sale Of Stock [Line Items]
Common stock, shares issued													386,881
Stock Sale Commission Percentage											3.00%
Proceeds from the sale of common stock													$ 1,117
Open Market Sales Agreement [Member] \| Maximum [Member] \| Jeffries LLC [Member]
Sale Of Stock [Line Items]
Aggregate offering price of securities											$ 80,000							80,000
2022 Shelf Registration Statement [Member] \| Maximum [Member]
Sale Of Stock [Line Items]
Aggregate offering price of securities											$ 300,000							$ 300,000
Common Stock
Sale Of Stock [Line Items]
Common stock, shares issued													386,881
Restricted stock units vested shares													16,142	94,454	83,793	7,500	89,075	109,943
Restricted Stock Units [Member] \| Common Stock \| Board of Directors Chairman [Member] \| June 2022
Sale Of Stock [Line Items]
Restricted stock units vested shares										11,876
Performance Restricted Stock Units [Member] \| Common Stock \| Executive Officers [Member] \| March 2022
Sale Of Stock [Line Items]
Restricted stock units vested shares											37,999
Time-based Restricted Stock Units [Member] \| 2014 Equity Incentive Plan [Member] \| Executive Officers [Member] \| March 2021
Sale Of Stock [Line Items]
Restricted stock units, vested					15,999
Time-based Restricted Stock Units [Member] \| 2014 Equity Incentive Plan [Member] \| Executive Officers [Member] \| February 2020
Sale Of Stock [Line Items]
Restricted stock units, vested						15,999
Time-based Restricted Stock Units [Member] \| 2014 Equity Incentive Plan [Member] \| Interim Principal Financial and Accounting Officer [Member] \| June 2022
Sale Of Stock [Line Items]
Restricted stock units, vested																			0
Time-based Restricted Stock Units [Member] \| 2014 Equity Incentive Plan [Member] \| Chief Executive Officer [Member] \| October 2021
Sale Of Stock [Line Items]
Restricted stock units, vested		8,875		8,875			8,875	35,500
Time-based Restricted Stock Units [Member] \| Common Stock \| Director [Member] \| June 2022
Sale Of Stock [Line Items]
Vesting period of awards granted			1 year							1 year
Restricted stock units vested shares			59,380							43,200
Time-based Restricted Stock Units [Member] \| Common Stock \| Executive Officers [Member] \| December 2021
Sale Of Stock [Line Items]
Restricted stock units vested shares			26,199
Time-based Restricted Stock Units [Member] \| Common Stock \| Executive Officers [Member] \| February 2022
Sale Of Stock [Line Items]
Vesting period of awards granted						3 years
Restricted stock units vested shares						42,920
Time-based Restricted Stock Units [Member] \| Common Stock \| Executive Officers [Member] \| March 2021
Sale Of Stock [Line Items]
Vesting period of awards granted															3 years
Restricted stock units vested shares															15,999
Time-based Restricted Stock Units [Member] \| Common Stock \| Executive Officers [Member] \| February 2020
Sale Of Stock [Line Items]
Vesting period of awards granted						3 years						3 years
Restricted stock units vested shares						15,999						32,666
Time-based Restricted Stock Units [Member] \| Common Stock \| Executive Officers [Member] \| October 2022
Sale Of Stock [Line Items]
Restricted stock units vested shares	7,267
Time-based Restricted Stock Units [Member] \| Common Stock \| Former Chief Executive Officer [Member] \| June 2022
Sale Of Stock [Line Items]
Restricted stock units vested shares										33,999
Time-based Restricted Stock Units [Member] \| Common Stock \| Interim Principal Financial and Accounting Officer [Member] \| September 2022
Sale Of Stock [Line Items]
Restricted stock units, vested									7,500
Time-based Restricted Stock Units [Member] \| Common Stock \| Chief Executive Officer [Member] \| March 2022
Sale Of Stock [Line Items]
Vesting period of awards granted											3 years
Restricted stock units vested shares											39,278

Stock-Based Compensation - Stock Award Modifications (Details) - Former President and C E O [Member] - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	9 Months Ended
	Feb. 28, 2022	Nov. 30, 2021	Sep. 30, 2022	Sep. 30, 2022
Modified Awards [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of awards granted		12 months
Share-based Compensation Arrangement Period During Which Continuous Service Must Be Performed For Awards To Be Modified		12 months
Awards that would have vested during the period following the consulting period are deemed to be type 3 modifications		12 months
Term of modified exercise period of awards		18 months
Modified Awards [Member] \| Performance Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Modification of stock options			$ 0
Modified Awards [Member] \| Performance Restricted Stock Units [Member] \| General and Administrative [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total incremental stock compensation expense relating to modifications of Stock Awards				$ 2,563
Incremental stock compensation expense relating to modification of stock options				$ 1,679
Type 4 modification [Member] \| Performance Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock units, vested	17,333

CONDENSED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenue:
Total revenue	$ 4,866	$ 10,813	$ 17,964	$ 38,606
Operating expenses:
Cost of goods sold	1,558	3,055	5,566	5,136
Research and development	25,451	24,691	80,095	65,869
General and administrative	6,755	6,912	21,191	23,829
Total operating expenses	33,764	34,658	106,852	94,834
Operating loss	(28,898)	(23,845)	(88,888)	(56,228)
Other income, net	866	665	2,712	1,093
Net loss	$ (28,032)	$ (23,180)	$ (86,176)	$ (55,135)
Net loss per share:
Basic	$ (0.52)	$ (0.43)	$ (1.59)	$ (1.03)
Diluted	$ (0.52)	$ (0.43)	$ (1.59)	$ (1.03)
Weighted average shares:
Basic	54,235,695	53,726,123	54,038,239	53,616,753
Diluted	54,235,695	53,726,123	54,038,239	53,616,753
Other comprehensive income (loss), net of tax of $0:
Change in unrealized gains (losses) on available-for-sale marketable securities	$ 291	$ (101)	$ 1,233	$ (1,790)
Total comprehensive loss	(27,741)	(23,281)	(84,943)	(56,925)
Collaborative revenue
Revenue:
Total revenue	2,471	7,443	10,631	15,446
Commercial supply revenue
Revenue:
Total revenue	1,252	$ 3,370	5,843	8,160
Royalty revenue
Revenue:
Total revenue	167		415
License and milestone fees
Revenue:
Total revenue	910		910	$ 15,000
Clinical compound revenue
Revenue:
Total revenue	$ 66		$ 165

Collaboration and Licensing Agreements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended
	Oct. 31, 2020	May 31, 2018	Sep. 30, 2023	May 17, 2018
Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 2 [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of net profit sharing		50.00%
License Agreement with Maruishi Pharmaceutical Co. Ltd [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Earned milestone payment			$ 1,449
CSL Vifor Maximum [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 1 [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential sales-based milestone payments	$ 240,000
CSL Vifor [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 1 [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of net profit sharing	40.00%
Affiliated Entity [Member] \| CSL Vifor [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 1 [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of net profit sharing	60.00%
Affiliated Entity [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd Agreement No 2 [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Percentage of net profit sharing		50.00%
Affiliated Entity [Member] \| Vifor Fresenius Medical Care Renal Pharma Ltd. [Member] \| Maximum [Member] \| Regulatory and Commercial Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Potential milestone payments				$ 440,000

Restricted Cash - Additional Information (Detail) $ in Thousands	Sep. 30, 2023 USD ($)	May 31, 2023 ft²	Dec. 31, 2022 USD ($)
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash, current assets	$ 408		$ 408
Restricted cash, long-term assets	1,500
New Stamford Lease [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Letters of credit, face amount that can be reduced	500
Restricted cash, long-term assets	1,500
Area of Real Estate Property Subject to Lease \| ft²		26,374
Stamford Lease [Member]
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash, current assets	$ 408		$ 408

Prepaid Expenses - Additional Information (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Prepaid expenses
Prepaid expenses	$ 12,658	$ 16,267
Prepaid R&D clinical costs	11,133	15,188
Prepaid insurance	865	543
Other prepaid costs	$ 660	$ 536

Inventory, net - Schedule of Inventories (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Inventory, net
Raw materials	$ 2,692	$ 1,918
Work-in-process	607	499
Finished goods	4
Inventory gross	3,303	2,417
Less Inventory Reserve for Obsolescence	(37)	(34)
Total	$ 3,266	$ 2,383

Accounts Payable and Accrued Expenses - Schedule of Accounts Payable and Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Accounts Payable and Accrued Expenses
Accounts payable	$ 7,978	$ 9,604
Accrued research projects	6,304	5,200
Accrued compensation and benefits	5,370	5,219
Accrued professional fees and other	2,732	1,517
Total	$ 22,384	$ 21,540

Stock-Based Compensation - Summary of Stock Option Activity (Detail)	3 Months Ended	9 Months Ended
	Sep. 30, 2022 shares	Sep. 30, 2023 $ / shares shares
Stock-Based Compensation
Number of Options, Outstanding, Beginning Balance		7,689,449
Number of Options, Granted		1,954,668
Number of Options, Exercised		(93,218)
Number of Options, Forfeited		(177,085)
Number of Options, Expired		(1,332,923)
Number of Options, Outstanding, Ending Balance	7,654,523	8,040,891
Number of Options, Options exercisable		4,583,227
Weighted-Average Exercise Price, Outstanding, Beginning Balance \| $ / shares		$ 14.35
Weighted-Average Exercise Price, Granted \| $ / shares		8.31
Weighted-Average Exercise Price, Exercised \| $ / shares		6.00
Weighted-Average Exercise Price, Forfeited \| $ / shares		11.19
Weighted-Average Exercise Price, Expired \| $ / shares		14.48
Weighted-Average Exercise Price, Outstanding, Ending Balance \| $ / shares		$ 13.03

Restricted Cash - Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Dec. 31, 2021
Restricted Cash
Cash and cash equivalents	$ 62,875	$ 63,741
Restricted cash, current assets	408	408
Restricted cash, long-term assets	1,500
Total cash, cash equivalents, and restricted cash shown in the Condensed Statements of Cash Flows	$ 64,783	$ 64,149	$ 43,214	$ 13,861

CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
CONDENSED BALANCE SHEETS
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	54,471,829	53,797,341
Common stock, shares outstanding	54,471,829	53,797,341

Commitments and Contingencies - Schedule of Future Minimum Lease Payments under Non-cancellable Operating Leases, Reconciliation of Undiscounted Cash Flows to the Operating Lease Liability (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Operating Lease Liabilities, Payments Due [Abstract]
2023 (Excluding the nine months ended September 30, 2023)	$ 503
2024	108
2025	1,298
2026	1,330
2027	1,363
2028	1,398
Thereafter	8,874
Total future minimum lease payments, undiscounted	14,874
Less imputed interest	(7,562)
Operating lease liabilities	7,312
Operating lease liabilities reported as of September 30, 2023:
Operating lease liabilities - current	497	$ 1,918
Operating lease liabilities - non-current	6,815
Total	$ 7,312

Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Financial assets
Available-for-sale marketable securities	$ 20,413	$ 93,008
Restricted cash	408	408
Restricted cash, non-current	1,500
Recurring [Member]
Financial assets
Total financial assets	85,196	157,157
U.S. Government Agency Obligations [Member]
Financial assets
Available-for-sale marketable securities	9,103	8,877
U.S. Government Agency Obligations [Member] \| Recurring [Member]
Financial assets
Available-for-sale marketable securities	9,103	8,877
Corporate Bonds [Member]
Financial assets
Available-for-sale marketable securities	9,285	35,185
Corporate Bonds [Member] \| Recurring [Member]
Financial assets
Available-for-sale marketable securities	9,285	35,185
Commercial Paper [Member]
Financial assets
Available-for-sale marketable securities		26,875
Municipal Bonds [Member]
Financial assets
Available-for-sale marketable securities	2,025	22,071
Municipal Bonds [Member] \| Recurring [Member]
Financial assets
Available-for-sale marketable securities	2,025	22,071
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Recurring [Member]
Financial assets
Total financial assets	64,783	64,149
Significant Other Observable Inputs (Level 2) [Member] \| Recurring [Member]
Financial assets
Total financial assets	20,413	93,008
Significant Other Observable Inputs (Level 2) [Member] \| U.S. Government Agency Obligations [Member] \| Recurring [Member]
Financial assets
Available-for-sale marketable securities	9,103	8,877
Significant Other Observable Inputs (Level 2) [Member] \| Corporate Bonds [Member] \| Recurring [Member]
Financial assets
Available-for-sale marketable securities	9,285	35,185
Significant Other Observable Inputs (Level 2) [Member] \| Municipal Bonds [Member] \| Recurring [Member]
Financial assets
Available-for-sale marketable securities	2,025	22,071
Money Market Funds [Member] \| Recurring [Member]
Financial assets
Cash and cash equivalents	62,875	63,741
Restricted cash	1,908	408
Money Market Funds [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Recurring [Member]
Financial assets
Cash and cash equivalents	62,875	63,741
Restricted cash	$ 1,908	408
Commercial Paper [Member] \| Recurring [Member]
Financial assets
Available-for-sale marketable securities		26,875
Commercial Paper [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Recurring [Member]
Financial assets
Available-for-sale marketable securities		$ 26,875

Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Sep. 30, 2023
Business.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosure of contingent assets and liabilities, as of the date of the financial statements as well as the reported amounts of revenues and expenses during the reporting period. The more significant estimates include the fair value of marketable securities that are classified as level 2 of the fair value hierarchy, the amount and periods over which certain revenues will be recognized, including licensing and collaborative revenue recognized from non-refundable up-front and milestone payments, related party accounts receivable reserve, as applicable, inventory valuation and related reserves, research and development, or R&D, clinical costs and accrued research projects included in prepaid expenses and accounts payable and accrued expenses, the amount of non-cash compensation costs related to share-based payments to employees and non-employees, the amount of lease incentives, as applicable, and the incremental borrowing rate used in lease calculations, and the likelihood of realization of deferred tax assets. The impact from global economic conditions and potential and continuing disruptions to and volatility in the credit and equity markets in the United States and worldwide are highly uncertain and cannot be predicted, including impacts from the COVID-19 pandemic or future public health crises, geopolitical tensions, such as the ongoing military conflict between Russia and Ukraine, the conflict between Israel and Hamas, and government actions implemented as a result of either of the foregoing, high rates of inflation, rising interest rates, uncertainty and liquidity concerns in the broader financial services industry, such as those caused by certain recent banking failures, and a potential recession in the United States. Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgment. As of the date of issuance of these condensed financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the reported amounts of assets and liabilities or the disclosure of contingent assets and liabilities. These estimates, however, may change as new events occur and additional information is obtained, and are recognized in the condensed financial statements as soon as they become known. Actual results could differ materially from the Company’s estimates and assumptions.
Significant Accounting Policies	Significant Accounting Policies There have been no material changes to the significant accounting policies previously disclosed in Note 2 to the Financial Statements in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022.

Subsequent Event (Details) - HCR Agreement $ in Thousands	Nov. 01, 2023 USD ($) agreement
Subsequent Event [Line Items]
Upfront payment receivable, net of certain expenses	$ 17,500
Subsequent Event [Member]
Subsequent Event [Line Items]
Maximum consideration for royalties sold or agreed to sell	40,000
Potential sales-based milestone payments	2,500
Subsequent Event [Member] \| If, prior to December 31, 2023, pricing for Kapruvia (difelikefalin) in Germany is approved above a certain threshold amount per dose
Subsequent Event [Line Items]
Upfront payment receivable, net of certain expenses	$ 20,000
Subsequent Event [Member] \| If the 2029 Threshold is achieved on or prior to December 31, 2029
Subsequent Event [Line Items]
Collaboration And Licensing Agreement, Threshold Number Of Times Of Aggregate Payments Made By Counterparty, Considered For Termination Of Agreement \| agreement	2
Subsequent Event [Member] \| If the 2029 Threshold is not achieved on or prior to December 31, 2029
Subsequent Event [Line Items]
Collaboration And Licensing Agreement, Threshold Number Of Times Of Aggregate Payments Made By Counterparty, Considered For Termination Of Agreement \| agreement	2.8

Available-for-Sale Marketable Securities - Summary of Available-for-Sale Marketable Securities by Major Type of Security (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 20,852	$ 94,680
Gross Unrealized Gains		2
Gross Unrealized Losses	(439)	(1,674)
Estimated fair value	20,413	93,008
U.S. Government Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	9,500	9,500
Gross Unrealized Losses	(397)	(623)
Estimated fair value	9,103	8,877
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	9,327	35,828
Gross Unrealized Losses	(42)	(643)
Estimated fair value	9,285	35,185
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost		26,879
Gross Unrealized Gains		2
Gross Unrealized Losses		(6)
Estimated fair value		26,875
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	2,025	22,473
Gross Unrealized Losses		(402)
Estimated fair value	$ 2,025	$ 22,071

Available-for-Sale Marketable Securities - Additional Information (Detail) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023 USD ($) position	Dec. 31, 2022 USD ($) position
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale allowance for credit loss \| $	$ 0	$ 0
Available-for-sale unrealized credit losses \| $	$ 0	$ 0
Number of available-for-sale marketable securities in unrealized loss positions	7	35
Total number of positions	9	39
Number of positions of available-for-sale in unrealized loss position for 12 months or greater	6
U.S. Government Agency Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of available-for-sale marketable securities in unrealized loss positions	3
Total number of positions	3
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of available-for-sale marketable securities in unrealized loss positions	4
Total number of positions	4
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Number of available-for-sale marketable securities in unrealized loss positions	0
Total number of positions	2