Ardelyx (ARDX) 10-Q 2 May 24 2024 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2024	Apr. 26, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2024
Document Transition Report	false
Entity File Number	001-36485
Entity Registrant Name	ARDELYX, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	26-1303944
Entity Address, Address Line One	400 Fifth Avenue
Entity Address, Address Line Two	Suite 210
Entity Address, City or Town	Waltham
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02451
City Area Code	510
Local Phone Number	745-1700
Title of 12(b) Security	Common Stock, par value $0.0001
Trading Symbol	ARDX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		233,976,572
Entity Central Index Key	0001437402
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONDENSED BALANCE SHEETS

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 36,147	$ 21,470
Short-term investments	166,431	162,829
Accounts receivable	28,162	22,031
Inventory	9,813	12,448
Prepaid commercial manufacturing	5,519	18,925
Prepaid expenses and other current assets	11,867	8,408
Total current assets	257,939	246,111
Inventory, non-current	69,045	37,039
Prepaid commercial manufacturing, non-current	4,235	4,235
Right-of-use assets	4,641	5,589
Property and equipment, net	1,019	1,009
Other assets	5,503	3,596
Total assets	342,382	297,579
Current liabilities:
Accounts payable	17,277	11,138
Accrued compensation and benefits	6,727	12,597
Current portion of operating lease liability	4,314	4,435
Deferred revenue	6,586	7,182
Accrued expenses and other current liabilities	21,991	15,041
Total current liabilities	56,895	50,393
Operating lease liability, net of current portion	778	1,725
Long-term debt, net of current portion	99,834	49,822
Deferred revenue, non-current	12,103	8,644
Deferred royalty obligation related to the sale of future royalties	21,881	20,179
Total liabilities	191,491	130,763
Commitments and contingencies (Note 14)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 5,000,000 shares authorized; no shares issued and outstanding as of March 31, 2024 and December 31, 2023, respectively.	0	0
Common stock, $0.0001 par value; 500,000,000 shares authorized; 233,959,744 and 232,453,190 shares issued and outstanding as of March 31, 2024 and December 31, 2023, respectively.	23	23
Additional paid-in capital	1,023,610	1,012,773
Accumulated deficit	(872,722)	(846,204)
Accumulated other comprehensive (loss) income	(20)	224
Total stockholders’ equity	150,891	166,816
Total liabilities and stockholders’ equity	$ 342,382	$ 297,579

CONDENSED BALANCE SHEETS (Paren

CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	233,959,744	232,453,190
Common stock, shares outstanding (in shares)	233,959,744	232,453,190

CONDENSED STATEMENTS OF OPERATI

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Revenues:
Total revenues	$ 46,023	$ 11,369
Cost of goods sold:
Total cost of goods sold	7,128	1,537
Operating expenses:
Research and development	10,579	9,093
Selling, general and administrative	52,994	26,803
Total operating expenses	63,573	35,896
Loss from operations	(24,678)	(26,064)
Interest expense	(2,356)	(1,028)
Non-cash interest expense related to the sale of future royalties	(1,702)	(969)
Other income, net	2,339	1,302
Loss before provision for income taxes	(26,397)	(26,759)
Provision for income taxes	121	14
Net loss	$ (26,518)	$ (26,773)
Net loss per share of common stock - basic (in dollars per share)	$ (0.11)	$ (0.13)
Net loss per share of common stock - diluted (in dollars per share)	$ (0.11)	$ (0.13)
Shares used in computing net loss per share - basic (in shares)	233,065,960	207,023,127
Shares used in computing net loss per share - diluted (in shares)	233,065,960	207,023,127
Comprehensive loss:
Net loss	$ (26,518)	$ (26,773)
Unrealized (losses) gains on available-for-sale securities	(244)	34
Comprehensive loss	(26,762)	(26,739)
Product sales, net
Revenues:
Total revenues	43,512	11,355
Cost of goods sold:
Total cost of goods sold	1,013	372
Product supply revenue
Revenues:
Total revenues	2,126	2
Licensing revenue
Revenues:
Total revenues	17	12
Non-cash royalty revenue related to the sale of future royalties
Revenues:
Total revenues	368	0
Other cost of revenue
Cost of goods sold:
Total cost of goods sold	$ 6,115	$ 1,165

CONDENSED STATEMENTS OF CHANGES

CONDENSED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning balance (in shares) at Dec. 31, 2022		198,575,016
Beginning balance at Dec. 31, 2022	$ 98,329	$ 20	$ 878,500	$ (780,137)	$ (54)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock purchase plan (in shares)		165,969
Issuance of common stock under employee stock purchase plan	138		138
Issuance of common stock upon exercise of options (in shares)		36,001
Issuance of common stock upon exercise of options	62		62
Issuance of common stock upon vesting of restricted stock units (in shares)		207,773
Issuance of common stock in at the market offering (in shares)		15,477,291
Issuance of common stock in at the market offering	50,719	$ 1	50,718
Stock-based compensation	2,912		2,912
Unrealized (losses) gains on available-for-sale securities	34				34
Net loss	(26,773)			(26,773)
Ending balance (in shares) at Mar. 31, 2023		214,462,050
Ending balance at Mar. 31, 2023	125,421	$ 21	932,330	(806,910)	(20)
Beginning balance (in shares) at Dec. 31, 2023		232,453,190
Beginning balance at Dec. 31, 2023	166,816	$ 23	1,012,773	(846,204)	224
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock purchase plan (in shares)		253,312
Issuance of common stock under employee stock purchase plan	$ 1,038		1,038
Issuance of common stock upon exercise of options (in shares)	702,000	701,578
Issuance of common stock upon exercise of options	$ 2,183		2,183
Issuance of common stock upon vesting of restricted stock units (in shares)		551,664
Stock-based compensation	7,616		7,616
Unrealized (losses) gains on available-for-sale securities	(244)				(244)
Net loss	(26,518)			(26,518)
Ending balance (in shares) at Mar. 31, 2024		233,959,744
Ending balance at Mar. 31, 2024	$ 150,891	$ 23	$ 1,023,610	$ (872,722)	$ (20)

CONDENSED STATEMENTS OF CASH FL

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating activities
Net loss	$ (26,518)	$ (26,773)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	435	(3)
Non-cash lease expense	948	902
Stock-based compensation	7,616	2,912
Non-cash interest expense	1,753	1,044
Other, net	(1,265)	499
Changes in operating assets and liabilities:
Accounts receivable	(6,131)	(4,387)
Inventory	(29,371)	(16,601)
Prepaid commercial manufacturing	13,406	(268)
Prepaid expenses and other assets	(5,450)	(774)
Accounts payable	6,139	(346)
Accrued compensation and benefits	(5,870)	(2,474)
Operating lease liabilities	(1,068)	(937)
Accrued and other liabilities	6,791	(1,396)
Deferred revenue	2,863	3,807
Net cash used in operating activities	(35,722)	(44,795)
Investing activities
Proceeds from maturities and redemptions of investments	31,602	11,000
Purchases of investments	(34,024)	(20,763)
Purchases of property and equipment	(150)	(14)
Net cash used in investing activities	(2,572)	(9,777)
Financing activities
Proceeds from 2022 Loan, net of issuance costs	49,750	0
Proceeds from issuance of common stock in at the market offering, net of issuance costs	0	50,719
Proceeds from issuance of common stock under equity incentive and stock purchase plans	3,221	200
Net cash provided by financing activities	52,971	50,919
Net increase (decrease) in cash and cash equivalents	14,677	(3,653)
Cash and cash equivalents at beginning of period	21,470	96,140
Cash and cash equivalents at end of period	36,147	92,487
Supplementary disclosure of cash flow information:
Cash paid for interest	2,095	860
Cash paid for income taxes	$ 1	$ 0

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	ORGANIZATION AND BASIS OF PRESENTATION Ardelyx, Inc. (Company, we, us or our) is a biopharmaceutical company founded with a mission to discover, develop and commercialize innovative first-in-class medicines that meet significant unmet medical needs. We developed a unique and innovative platform that enabled the discovery of new biological mechanisms and pathways to develop potent, and efficacious therapies that minimize the side effects and drug-drug interactions frequently encountered with traditional, systemically absorbed medicines. The first molecule we discovered and developed was tenapanor, a minimally absorbed, first-in-class, oral, small molecule therapy. Tenapanor, branded as IBSRELA ® , is approved in the U.S. for the treatment of adults with irritable bowel syndrome with constipation (IBS-C). Tenapanor, branded as XPHOZAH ® , was approved by the U.S. Food and Drug Administration (U.S. FDA) on October 17, 2023, to reduce serum phosphorus in adults with chronic kidney disease (CKD) on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy. We operate in one business segment, which is the development and commercialization of biopharmaceutical products. Basis of Presentation These condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) and pursuant to the requirements of the Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules and regulations, certain footnotes or other financial information that are normally required by U.S. GAAP have been condensed or omitted. These condensed financial statements have been prepared on the same basis as our most recent annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments necessary to present fairly our financial position, results of operations, changes in stockholders’ equity, and cash flows for the interim periods presented. The accompanying condensed financial statements and related financial information should be read in conjunction with the audited financial statements and the related notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2023. The results for the three months ended March 31, 2024 are not necessarily indicative of results to be expected for the entire year ending December 31, 2024, or for any other interim period or future year. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes thereto. On an ongoing basis, management evaluates its estimates, including those related to recognition of revenue, clinical trial accruals, contract manufacturing accruals, expected demand for inventory, fair value of assets and liabilities, income taxes and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could materially differ from those estimates. Liquidity As of March 31, 2024, we had cash, cash equivalents and short-term investments of approximately $202.6 million. We have incurred operating losses since inception in 2007 and our accumulated deficit as of March 31, 2024 is $872.7 million. We have addressed our operating cash flow requirements through cash generated from product sales of IBSRELA and XPHOZAH, proceeds from the sale of shares of our common stock under our at-the-market offering, from the receipt of milestone payments from our collaboration partners and payments from our Japanese collaboration partner under the second amendment to our License Agreement, and through funds from our loan agreements with SLR Investment Corp. (SLR), as amended. We believe our available cash, cash equivalents and short-term investments as of March 31, 2024 will be sufficient to fund our planned operations for at least a period of one year from the issuance of these condensed financial statements. Summary of Significant Accounting Policies Our significant accounting policies are described in Note 2 to our audited financial statements for the fiscal year ended December 31, 2023, included in our Annual Report on Form 10-K. There have been no material changes in our significant accounting policies as previously disclosed in our Annual Report on Form 10-K for the fiscal year ended December 31, 2023. Recent Accounting Pronouncements New Accounting Pronouncements - Recently Adopted We have adopted no new accounting pronouncements subsequent to filing our most recent Annual Report on Form 10-K. Recent Accounting Pronouncements Not Yet Adopted In October 2023, the Financial Accounting Standards Board (FASB) issued ASU No. 2023-06, Disclosure Improvements - Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative. The amendments in this Update modify the disclosure or presentation requirements of a variety of Topics in the Codification. The amendments are in response to the U.S. Securities and Exchange Commission's (SEC) Release No. 33-10532, Disclosure Update and Simplification, in which the SEC referred certain of its disclosure requirements that overlap with, but require incremental information to, generally accepted accounting principles to the FASB for potential incorporation into the Codification. For entities subject to the SEC’s existing disclosure requirements and for entities required to file or furnish financial statements with or to the SEC in preparation for the sale of or for purposes of issuing securities that are not subject to contractual restrictions on transfer, the effective date for each amendment will be the date on which the SEC’s removal of that related disclosure from Regulation S-X or Regulation S-K becomes effective, with early adoption prohibited. For all other entities, the amendments will be effective two years later. For all entities, if by June 30, 2027, the SEC has not removed the applicable requirement from Regulation S-X or Regulation S-K, the pending content of the related amendment will be removed from the Codification and will not become effective for any entity. Management is currently assessing the impact of this standard on the Company’s financial statements. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) - Improvements to Reportable Segment Disclosures. This Update requires publicly traded entities to provide enhanced disclosures about significant segment expenses regularly reviewed by the chief operating decision maker (CODM), including public traded entities with a single reportable segment. The amendments in this update are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. Management is currently assessing the impact of this standard on the Company’s financial statements. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740) - Improvements to Income Tax Disclosures, an amendment which modifies the measurement and recognition of credit losses for most financial assets and certain other instruments. The amendments in this Update provide more transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. For public business entities, the amendments in this Update are effective for annual periods beginning after December 15, 2024. Early adoption is permitted on a prospective basis for annual financial statements that have not yet been issued or made available for issuance. Management is currently assessing the impact of this standard on the Company’s financial statements. In March 2024, the FASB issued ASU No. 2024-02, Codification Improvements - Amendments to Remove References to the Concepts Statements, an amendment to the Codification which removes references to various FASB Concepts Statements. The amendments apply to all reporting entities within the scope of the affected accounting guidance, but in most instances the references removed are extraneous and not required to understand or apply the guidance. Generally, the amendments in ASU 2024-02 are not intended to result in significant accounting changes for most entities. The amendments in this update are effective for fiscal years beginning after December 15, 2024 and are not expected to have a significant impact on our financial statements.

Cash, Cash Equivalents and Inve

Cash, Cash Equivalents and Investments	3 Months Ended
	Mar. 31, 2024
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Investments	CASH, CASH EQUIVALENTS AND INVESTMENTS Securities classified as cash, cash equivalents and short-term investments as of March 31, 2024 and December 31, 2023 are summarized below (in thousands): March 31, 2024 Gross Unrealized Amortized Cost Gains Losses Fair Value Cash and cash equivalents: Cash $ 3,844 $ — $ — $ 3,844 Money market funds 32,303 — — 32,303 Total cash and cash equivalents 36,147 — — 36,147 Short-term investments: U.S. government-sponsored agency bonds $ 101,706 $ 34 $ (23) $ 101,717 Commercial paper 53,549 11 (39) 53,521 Asset-backed securities 8,707 — (3) 8,704 U.S. treasury securities 2,489 — — 2,489 Total short-term investments 166,451 45 (65) 166,431 Total cash, cash equivalents and investments $ 202,598 $ 45 $ (65) $ 202,578 December 31, 2023 Gross Unrealized Amortized Cost Gains Losses Fair Value Cash and cash equivalents: Cash $ 2,829 $ — $ — $ 2,829 Money market funds 18,641 — — 18,641 Total cash and cash equivalents 21,470 — — 21,470 Short-term investments: U.S. government-sponsored agency bonds $ 101,892 $ 235 $ (34) $ 102,093 Commercial paper 49,630 41 (17) 49,654 Asset-backed securities 8,628 2 (5) 8,625 U.S. treasury securities 2,455 2 — 2,457 Total short-term investments 162,605 280 (56) 162,829 Total cash, cash equivalents and investments $ 184,075 $ 280 $ (56) $ 184,299 Cash equivalents consist of money market funds with original maturities of three months or less at the time of purchase, and the carrying amount is a reasonable approximation of fair value. We invest our cash in high quality securities of financial and commercial institutions. These securities are carried at fair value, which is based on readily available market information, with unrealized gains and losses included in accumulated other comprehensive loss within stockholders’ equity on our balance sheets. We use the specific identification method to determine the amount of realized gains or losses on sales of marketable securities. Realized gains or losses have not been significant and are included in other income, net, in the statement of operations and comprehensive loss. All of the short-term available-for sale securities held as of March 31, 2024 and December 31, 2023 had contractual maturities of less than one year. Our available-for-sale securities are subject to a periodic impairment review. We consider a debt security to be impaired when its fair value is less than its carrying cost, in which case we would further review the investment to determine whether it is other-than-temporarily impaired. When we evaluate an investment for other-than-temporary impairment, we review factors such as the length of time and extent to which fair value has been below cost basis, the financial condition of the issuer and any changes thereto, intent to sell, and whether it is more likely than not we will be required to sell the investment before the recovery of its cost basis. If an investment is other-than-temporarily impaired or subject to credit losses, we write it down through the statement of operations and comprehensive loss to its fair value and establish that value as a new cost basis for the investment. Our unrealized losses as of March 31, 2024 and December 31, 2023 were not material. We determined that none of our available-for-sale securities were other-than-temporarily impaired as of March 31, 2024 and December 31, 2023, and no investment was in a continuous unrealized loss position for more than one year. As such, we believe that it is more likely than not that the investments will be held until maturity or a forecasted recovery of fair value.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The three-level hierarchy for the inputs to valuation techniques is briefly summarized as follows: Level 1 – Valuations are based on quoted prices in active markets for identical assets or liabilities and readily accessible by us at the reporting date. Level 2 – Valuations based on inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Valuations based on unobservable inputs for which there is little or no market data, which require us to develop our own assumptions. The following table sets forth the fair value of our financial assets and liabilities that are measured or disclosed on a recurring basis by level within the fair value hierarchy (in thousands): March 31, 2024 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 32,303 $ 32,303 $ — $ — U.S. government-sponsored agency bonds 101,717 — 101,717 — Commercial paper 53,521 — 53,521 — Asset-backed securities 8,704 — 8,704 — U.S. treasury securities 2,489 — 2,489 — Total $ 198,734 $ 32,303 $ 166,431 $ — Liabilities: Derivative liabilities for exit fee $ 834 $ — $ — $ 834 Total $ 834 $ — $ — $ 834 December 31, 2023 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 18,641 $ 18,641 $ — $ — U.S. government-sponsored agency bonds 102,093 — 102,093 — Commercial paper 49,654 — 49,654 — Asset-backed securities 8,625 — 8,625 — U.S. treasury securities 2,457 — 2,457 — Total $ 181,470 $ 18,641 $ 162,829 $ — Liabilities: Derivative liability for exit fees $ 675 $ — $ — $ 675 Total $ 675 $ — $ — $ 675 Where quoted prices are available in an active market, securities are classified as Level 1. We classify money market funds as Level 1. When quoted market prices are not available for the specific security, we estimate fair value by using benchmark yields, reported trades, broker/dealer quotes and issuer spreads. We classify U.S. government-sponsored agency bonds, U.S. treasury securities, corporate bonds, commercial paper, and asset-backed securities as Level 2. In certain cases, where there is limited activity or less transparency around inputs to valuation, securities or derivative liabilities, such as the 2022 Exit Fee, as defined and discussed in Note 9. Derivative Liabilities , are classified as Level 3. The carrying amounts reflected in the condensed balance sheets for accounts receivable, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values at both March 31, 2024 and December 31, 2023, due to their short-term nature. Based on our procedures under the expected credit loss model, including an assessment of unrealized losses in our portfolio, we concluded that any unrealized losses on our marketable securities were not attributable to credit and, therefore, we have not recorded an allowance for credit losses for these securities as of March 31, 2024 and December 31, 2023. Fair Value of Debt The principal amount outstanding under our term loan facilities is subject to a variable interest rate. Therefore, we believe the carrying amount of the term loan facility approximates fair value as of March 31, 2024 and December 31, 2023. See Note 8. Borrowing for a description of the Level 2 inputs used to estimate the fair value of the liability. The carrying value of the deferred royalty obligation related to the sale of future royalties approximates its fair value as of March 31, 2024 and December 31, 2023 and is based on our current estimates of future royalties and commercialization milestones expected to be paid to us by Kyowa Kirin Co., Ltd. (Kyowa Kirin) over the life of the agreement. See Note 7. Deferred Royalty Obligation Related to the Sale of Future Royalties for a description of the Level 3 inputs used to estimate the fair value of the liability.

Inventory

Inventory	3 Months Ended
	Mar. 31, 2024
Inventory Disclosure [Abstract]
Inventory	INVENTORY Inventory as of March 31, 2024 and December 31, 2023 consisted of the following (in thousands): March 31, 2024 December 31, 2023 Raw materials $ 20,906 $ 22,920 Work in process 54,206 24,582 Finished goods 3,746 1,985 Total $ 78,858 $ 49,487 Reported as: Inventory $ 9,813 $ 12,448 Inventory, non-current 69,045 37,039 Total $ 78,858 $ 49,487 In addition to inventory, we had prepaid commercial manufacturing of $9.8 million and $23.2 million as of March 31, 2024 and December 31, 2023, respectively, which consisted of prepayments to third party contract manufacturing organizations, including prepayments of $4.2 million as of both March 31, 2024 and December 31, 2023 that are expected to be converted into inventory after 12 months.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Revenue	REVENUE Total revenues during the three months ended March 31, 2024 and 2023 were as follows (in thousands): Three Months Ended March 31, 2024 2023 Product sales, net: IBSRELA $ 28,361 $ 11,355 XPHOZAH 15,151 — Total product sales, net 43,512 11,355 Product supply revenue 2,126 2 Licensing revenue 17 12 Non-cash royalty revenue related to the sale of future royalties 368 — Total revenues $ 46,023 $ 11,369 Revenue from Customers who contributed greater than 10% of our total gross product revenue during the three months ended March 31, 2024 and 2023 was as follows (as a percentage of total gross product revenue): Three Months Ended March 31, 2024 2023 BioRidge Pharma, LLC 39.9 % 17.6 % AmerisourceBergen Drug Corporation 18.3 % 21.6 % Cardinal Health 16.2 % 22.2 % McKesson Corporation 13.5 % 20.8 % The activities and ending reserve balances for each significant category of discounts and allowances, which constitute variable consideration, were as follows (in thousands): Discounts and Chargebacks Rebates, Wholesaler and GPO Fees Copay and Returns Total Balance as of December 31, 2023 $ 478 $ 4,234 $ 3,916 $ 8,628 Provisions 2,644 9,525 6,846 19,015 Credits/payments (2,467) (7,211) (3,852) (13,530) Balance as of March 31, 2024 $ 655 $ 6,548 $ 6,910 $ 14,113 Adjustments to prior period provisions recorded in the current period were not material.

Collaboration and Licensing Agr

Collaboration and Licensing Agreements	3 Months Ended
	Mar. 31, 2024
Collaboration and Licensing Agreements
Collaboration and Licensing Agreements	COLLABORATION AND LICENSING AGREEMENTS Kyowa Kirin Co., Ltd. (Kyowa Kirin) In November 2017, we entered into an exclusive license agreement with Kyowa Kirin (2017 Kyowa Kirin Agreement), under which we granted Kyowa Kirin an exclusive license to develop and commercialize certain NHE3 inhibitors including tenapanor in Japan for the treatment of cardiorenal diseases and conditions, excluding cancer. We retained the rights to tenapanor outside of Japan, and also retained the rights to tenapanor in Japan for indications other than those stated above. Pursuant to the 2017 Kyowa Kirin Agreement, Kyowa Kirin is responsible for all costs and expenses incurred in the development and commercialization of tenapanor for all licensed indications in Japan. We are responsible for supplying the tenapanor drug substance for Kyowa Kirin’s use in development and commercialization throughout the term of the 2017 Kyowa Kirin Agreement, provided that Kyowa Kirin may exercise an option to manufacture the tenapanor drug substance under certain conditions. In October 2022, we entered into a Commercial Supply Agreement with Kyowa Kirin to further define the obligations of the parties with respect to the commercial supply of tenapanor drug substance (2022 Kyowa Kirin Supply Agreement). As detailed below under the heading Deferred Revenue we have received advanced payments from Kyowa Kirin for the manufacturing of tenapanor drug substance that will be used to satisfy Kyowa Kirin needs. We assessed these arrangements in accordance with Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606) and related amendments (ASC 606) and concluded that the contract counterparty, Kyowa Kirin, is a customer. Under the terms of the 2017 Kyowa Kirin Agreement, we received $30.0 million in upfront license fees, which was recognized as revenue when the agreement was executed. Based on our assessment, management determined that the license and the manufacturing supply services were its material performance obligations at the inception of the 2017 Kyowa Kirin Agreement, and as such, each of the performance obligations is distinct. We may be entitled to receive up to $55.0 million in total development and regulatory milestones, of which $35.0 million has been received and recognized as revenue as of March 31, 2024. We may also be eligible to receive approximately ¥8.5 billion for commercialization milestones, or approximately $56.2 million at the currency exchange rate on March 31, 2024, as well as reimbursement of costs plus a reasonable overhead for the supply of product and royalties on net sales throughout the term of the agreement. As discussed in Note 7. Deferred Royalty Obligation Related to the Sale of Future Royalties , the future royalties and commercial milestone payments we may receive under the 2017 Kyowa Kirin Agreement will be remitted to HealthCare Royalty Partners IV, L.P. pursuant to a Royalty and Sales Milestone Interest Acquisition Agreement. The variable consideration related to the remaining milestone payments was fully constrained at March 31, 2024. In April 2022, we entered into a second amendment to the 2017 Kyowa Kirin Agreement (2022 Amendment). Under the terms of the 2022 Amendment, we and Kyowa Kirin agreed to a reduction in the royalty rate payable to us by Kyowa Kirin upon net sales of tenapanor for hyperphosphatemia in Japan. The royalty rate will be reduced from the high teens to low double digits for a two-year period of time following the first commercial sale in Japan, and then to mid-single digits for the remainder of the royalty term. As discussed in Note 7. Deferred Royalty Obligation Related to the Sale of Future Royalties , the future commercial milestones and royalties we may receive under the 2017 Kyowa Kirin Agreement will be remitted to HealthCare Royalty Partners IV, L.P. (HCR) pursuant to a Royalty and Sales Milestone Interest Acquisition Agreement (HCR Agreement). As consideration for the reduction in the royalty rate, Kyowa Kirin agreed to pay us up to an additional $40.0 million payable in two tranches, with the first payment due following Kyowa Kirin's filing with the Japanese Ministry of Health, Labour and Welfare (MHLW) of its application for marketing approval for tenapanor and the second payment due following Kyowa Kirin’s receipt of regulatory approval to market tenapanor for hyperphosphatemia in Japan, both of which occurred as of September 30, 2023. In October 2022, we announced that Kyowa Kirin submitted a New Drug Application (NDA) to the Japanese MHLW for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis, which resulted in payment to us from Kyowa Kirin for an aggregate of $35.0 million for milestone payments and payments under the 2022 Amendment. We received these payments during the fourth quarter of 2022 and recorded them as licensing revenue on our condensed statement of operations and comprehensive loss. In September 2023, we announced that Kyowa Kirin received approval from the Japanese MHLW for the NDA for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis, which resulted in payment to us from Kyowa Kirin for an aggregate of $30.0 million for milestone payments and payments under the 2022 Amendment. We received these payments in October 2023 and recorded them as licensing revenue on our condensed statement of operations and comprehensive loss when earned during the three months ended September 30, 2023. In February 2024, Kyowa Kirin announced the launch of tenapanor, marketed as PHOZEVEL ® , for patients in Japan. During the first quarter of 2024, we recognized $0.4 million of non-cash royalty revenue related to the sale of future royalties, which will be remitted to HCR in accordance with the HCR Agreement. During the three months ended March 31, 2024, we recognized $2.1 million of product supply revenue pursuant to the 2017 Kyowa Kirin Agreement. During the three months ended March 31, 2023, we recognized $2 thousand of product supply revenue pursuant to the 2017 Kyowa Kirin Agreement. During the three months ended March 31, 2024 and 2023, we did not recognize a material amount of licensing revenue pursuant to the 2017 Kyowa Kirin Agreement. Shanghai Fosun Pharmaceutical Industrial Development Co. Ltd. (Fosun Pharma) In December 2017, we entered into an exclusive license agreement with Fosun Pharma (Fosun Agreement) for the development, commercialization and distribution of tenapanor in China for both hyperphosphatemia and IBS-C. We assessed these arrangements in accordance with ASC 606 and concluded that the contract counterparty, Fosun Pharma, is a customer. Under the terms of the Fosun Agreement, we received $12.0 million in upfront license fees which was recognized as revenue when the agreement was executed. Based on our assessment, we determined that the license and the manufacturing supply services represented the material performance obligations at the inception of the agreement and, as such, each of the performance obligations are distinct. We may be entitled to receive development and commercialization milestones of up to $113.0 million, of which $8.0 million has been received and recognized as revenue as of March 31, 2024, as well as reimbursement of cost plus a reasonable overhead for the supply of product and tiered royalties on net sales ranging from the mid-teens to 20%. The variable consideration related to the remaining development milestone payments was fully constrained at March 31, 2024. In July 2023, we announced that an NDA for tenapanor had been accepted for review by China’s Center for Drug Evaluation of the National Medical Products Administration (NMPA) for the control of serum phosphorus in adult patients with CKD on hemodialysis. This acceptance triggered a $2.0 million milestone payment to us under the terms of the Fosun Agreement. We received this payment during the third quarter of 2023 and recorded it as licensing revenue on our condensed statement of operations and comprehensive loss when earned during the three months ended September 30, 2023. In October 2023, we announced that the U.S. FDA had approved XPHOZAH to reduce serum phosphorus in adults with CKD on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy. This triggered an additional $3.0 million milestone payment to us under the terms of the Fosun Agreement, which was received during the first quarter of 2024. Also, in October 2023, we announced that Fosun Pharma received approval from the Hong Kong Department of Health for the marketing application for tenapanor for the treatment of irritable bowel syndrome with constipation (IBS-C). During the three months ended March 31, 2024 and 2023, we did not recognize a material amount of revenue pursuant to the Fosun Agreement. Knight Therapeutics, Inc. (Knight) In March 2018, we entered into an exclusive license agreement with Knight Therapeutics, Inc., (Knight Agreement) for the development, commercialization and distribution of tenapanor in Canada for hyperphosphatemia and IBS-C. We assessed this arrangement in accordance with ASC 606 and concluded that the contract counterparty, Knight, is a customer. Based on our assessment, we determined that the license and the manufacturing supply services were the material performance obligations at the inception of the agreement and, as such, each of the performance obligations are distinct. Under the terms of the Knight Agreement, we received a $2.3 million non-refundable, one-time upfront payment in March 2018 and may be eligible to receive additional development and commercialization milestone payments worth up to CAD 22.2 million, or approximately $16.3 million at the currency exchange rate on March 31, 2024, of which $0.7 million has been received and recognized as revenue as of March 31, 2024. We are also eligible to receive royalties ranging from the mid-single digits to the low twenties throughout the term of the agreement, and a transfer price for manufacturing services. The variable consideration related to the remaining development milestone payments was fully constrained at March 31, 2024. During the three months ended March 31, 2024 and 2023, we did not recognize a material amount of revenue pursuant to the Knight Agreement. AstraZeneca AB (AstraZeneca) In June 2015, we entered into a termination agreement with AstraZeneca (AstraZeneca Termination Agreement) pursuant to which we have agreed to pay AstraZeneca (i) future royalties at a royalty rate of 10% of net sales of tenapanor or other NHE3 products by us or our licensees, and (ii) 20% of non-royalty revenue received from a new collaboration partner should we elect to license, or otherwise provide rights to develop and commercialize tenapanor or other NHE3 products, up to a maximum of $75.0 million in aggregate for (i) and (ii). As of March 31, 2024, to date in aggregate, we have recognized $32.4 million of the $75.0 million, which has been recorded as other cost of revenue on our condensed statements of operations and comprehensive loss. During the three months ended March 31, 2024, we recognized $4.7 million as other cost of revenue related to the AstraZeneca Termination Agreement. During the three months ended March 31, 2023 we recognized $1.2 million as other cost of revenue related to the AstraZeneca Termination Agreement. Deferred Revenue The following tables present changes in our current and non-current deferred revenue balances during the reporting period, which are all attributable to the 2017 Kyowa Kirin Agreement (in thousands): 2024 2023 Current Non-Current Current Non-Current Balance at January 1, $ 7,182 $ 8,644 $ 4,211 $ 9,025 Amounts invoiced as prepayments for product supply 732 3,459 525 3,282 Decrease for revenue recognized for product supply (1,328) — — — Reclassify amounts to be recognized in the next twelve months — — 809 (809) Balance at March 31, $ 6,586 $ 12,103 $ 5,545 $ 11,498

Deferred Royalty Obligation Rel

Deferred Royalty Obligation Related To The Sale Of Future Royalties	3 Months Ended
	Mar. 31, 2024
Advance Royalties [Abstract]
Deferred Royalty Obligation Related To The Sale Of Future Royalties	DEFERRED ROYALTY OBLIGATION RELATED TO THE SALE OF FUTURE ROYALTIES In June 2022, we and HealthCare Royalty Partners IV, L.P. (HCR) entered into a Royalty and Sales Milestone Interest Acquisition Agreement (HCR Agreement). Under the terms of the HCR Agreement, HCR has agreed to pay us up to $20.0 million in exchange for the royalty payments and commercial milestone payments (collectively the Royalty Interest Payments) that we may receive under our 2017 License Agreement with Kyowa Kirin based upon Kyowa Kirin's net sales of tenapanor in Japan for hyperphosphatemia. As consideration for the sale of the Royalty Interest Payments, HCR paid to us a $10.0 million upfront payment in June 2022 and a $5.0 million payment, which we received in October 2023, as a result of Kyowa Kirin's receipt of regulatory approval to market tenapanor for hyperphosphatemia in Japan. We are eligible to receive another $5.0 million payment in the event net sales by Kyowa Kirin in Japan exceed a certain annual target level by the end of 2025. The HCR Agreement is effective until terminated by the mutual agreement of the parties and contains customary representations and warranties and customary affirmative and negative covenants, including, among others, requirements as to prosecution, maintenance, defense and enforcement of certain patent rights in Japan, restrictions regarding our ability to forgive, release or reduce any Royalty Interest Payments due to us under the 2017 Kyowa Kirin Agreement, to create or incur any liens with respect to the Royalty Interest Payments, the 2017 Kyowa Kirin Agreement or certain patents, or to sell, license or transfer certain patents in the field and territory described in the 2017 Kyowa Kirin Agreement. In addition, the HCR Agreement contains customary events of default with respect to which we may incur indemnification obligations to HCR for any losses incurred by HCR and related parties as a result of the event of default, subject to a specified limitation of liability cap. Under the HCR Agreement, an event of default will occur if, among other things, any of the representations and warranties included in the HCR Agreement proves not to have been true and correct in all material respects, at the time it was made, we breach any of our covenants under the HCR Agreement, subject to specified cure periods with respect to certain breaches, we are in breach or default under the 2017 Kyowa Kirin Agreement in any manner which is likely to cause a material adverse effect on the Royalty Interest Payments, the occurrence of a termination of the 2017 Kyowa Kirin Agreement under certain circumstances or we or our assets become subject to certain legal proceedings, such as bankruptcy proceedings, or we are unable to pay our debts as they become due. The $10.0 million upfront payment from HCR received in June 2022 and the $5.0 million payment received in October 2023 have been recorded as a deferred royalty obligation related to the sale of future royalties (deferred royalty obligation) on our balance sheets. Due to our ongoing manufacturing obligations under the 2017 Kyowa Kirin Agreement, we account for the proceeds as imputed debt and therefore will recognize royalties earned under the arrangement as non-cash royalty revenue. Non-cash interest expense will be recognized over the life of the HCR Agreement using the effective interest method based on the imputed interest rate derived from estimated amounts and timing of future royalty payments to be received from Kyowa Kirin. As part of the sale, we incurred approximately $0.4 million in transaction costs, which, along with the deferred royalty obligation, are being amortized to non-cash interest expense over the estimated life of the HCR Agreement using the effective interest method. As future royalties are remitted to us by Kyowa Kirin, and subsequently from us to HCR, the balance of the deferred royalty obligation will be effectively repaid over the life of the HCR Agreement. There are a number of factors that could materially affect the fair value of the deferred royalty obligation. Such factors include, but are not limited to, the amount and timing of potential future royalty payments to be received from Kyowa Kirin under the 2017 Kyowa Kirin agreement, changing standards of care, the introduction of competing products, manufacturing or other delays, intellectual property matters, adverse events that result in governmental health authority imposed restrictions on the use of the drug products, significant changes in foreign exchange rates as the royalties remitted to HCR are made in U.S. dollars while the underlying sales of the products by Kyowa Kirin are made in Japanese yen, and other events or circumstances that could result in reduced royalty payments from Kyowa Kirin, which are not within our control, and all of which would result in a reduction of non-cash royalty revenues and the non-cash interest expense over the life of the deferred royalty obligation. We periodically assess the estimated royalty payments from Kyowa Kirin and, to the extent that the amount or timing of such payments is materially different than our original estimates, we prospectively adjust the imputed interest rate and the related amortization of the deferred royalty obligation. As of March 31, 2024, our effective interest rate used to amortize the liability is 33.7%. During the three months ended March 31, 2024, we recognized approximately $1.7 million of non-cash interest expense related to the deferred royalty obligation. During the three months ended March 31, 2023, we recognized approximately $1.0 million of non-cash interest expense related to the deferred royalty obligation. As of March 31, 2024, we have received no royalty payments from Kyowa Kirin and, therefore, the deferred royalty obligation has not begun to be reduced.

Borrowing

Borrowing	3 Months Ended
	Mar. 31, 2024
Debt Disclosure [Abstract]
Borrowing	BORROWING Solar Capital and Western Alliance Bank Loan Agreement In May 2018, we entered into a loan and security agreement (as amended on October 9, 2020, March 1, 2021, May 5, 2021, and July 29, 2021) (2018 Loan Agreement) with Solar Capital Ltd. and Western Alliance Bank (collectively, the 2018 Lenders). The 2018 Loan Agreement provided for a loan facility for up to $50.0 million with a maturity date of November 1, 2022 (2018 Loan). As of the Closing Date for the 2022 Loan, as discussed below, we owed $25.0 million in principal payments from the 2018 Loan, which we repaid in full at that time. As discussed in Note 9. Derivative Liabilities , in connection with entering into the 2018 Loan Agreement, we entered into an agreement pursuant to which we agreed to pay $1.5 million in cash upon the occurrence of certain conditions (2018 Exit Fee). Our obligations for the 2018 Exit Fee remained outstanding following the full repayment of the 2018 Loan in February 2022 until October 2023 when we received approval from the U.S. FDA for XPHOZAH to reduce serum phosphorus in adults with CKD on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy. This triggered our obligation to pay the 2018 Exit Fee to the 2018 Lenders and we subsequently paid the 2018 Exit Fee in October 2023. SLR Investment Corp. Loan Agreement On February 23, 2022 (Closing Date), we entered into a loan and security agreement (2022 Loan Agreement) with SLR Investment Corp. as collateral agent (Agent), and the lenders listed in the 2022 Loan Agreement (collectively, the 2022 Lenders). The 2022 Loan Agreement was subsequently amended in August 2022 (the First Amendment) and February 2023 (the Second Amendment). We concluded that the First Amendment and the Second Amendment were modifications to the 2022 Loan Agreement. The 2022 Loan Agreement, as amended by the First Amendment and the Second Amendment, provided for a senior secured loan facility, with $27.5 million (Term A Loan) funded on the Closing Date and an additional $22.5 million which was funded upon our election in October 2023 (Term B Loan, and together with the Term A Loan, the 2022 Original Loans). The 2022 Term A Loan funds were used to repay the 2018 Loan with the 2018 Lenders. On October 17, 2023, we entered into a Third Amendment (the Third Amendment) to the 2022 Loan Agreement by and between us and the 2022 Lenders. The Third Amendment, among other things, (1) provided us with the option to draw an additional $50.0 million of committed capital by March 15, 2024 (the Term C Loan) provided we have drawn the Term B Loan; and (2) provides us with the option to draw up to an additional $50.0 million of uncommitted capital by December 31, 2026, subject to approval by the Agent’s investment committee (the Term D Loan and together with the Term A, B, and C Loans, the Four 2022 Loans). In February 2024, we provided the Agent with notice of our decision to draw the Term C Loan to support the commercial launch of XPHOZAH and received the proceeds of the Term C Loan in March 2024. We concluded that the Third Amendment was a modification to the 2022 Original Loan Agreement. Under the Third Amendment, the maturity date for the Four 2022 Loans is March 1, 2027. The interest rate for each of the Term A Loan and the Term B Loan is 7.95% plus a SOFR value equal to 0.022% plus the 1-month CME Term SOFR reference rate as published by the CME Term SOFR Administrator on the CME Term SOFR Administrator’s Website, subject to a SOFR floor of one percent. The interest rate for each of the Term C Loan and the Term D Loan is 4.25% plus a SOFR value equal to 0.022% plus the 1-month CME Term SOFR reference rate as published by the CME Term SOFR Administrator on the CME Term SOFR Administrator’s Website, subject to a SOFR floor of 4.7%. In addition, pursuant to the Third Amendment, the period under which we are permitted to make interest-only payments on the Four 2022 Loans was extended to December 31, 2026, effective upon our decision to draw the Term B Loan in the amount of $22.5 million. We were obligated to pay $0.2 million, upon the closing of the Term A Loan, $0.1 million on the funding date of the Term B Loan, and $0.3 million on the funding date of the Term C Loan. In addition, we will be obligated to pay 0.5% of the aggregate original principal amount of the Term D Loan commitment, if requested by us and approved by the Agent’s investment committee, which shall be due on the earliest of (1) the funding of the Term D Loan, (2) if we request and the 2022 Lenders provide the Term D Loan commitment, the day immediately preceding the amortization date, and (3) if we request and the 2022 Lenders provide the Term D Loan commitment, the prepayment, refinancing, substitution or replacement of the Term C Loan on or prior to the date immediately preceding the amortization date. We are obligated to pay a final fee equal to 4.95% of the aggregate original principal amount of the Four 2022 Loans, to the extent such loans are funded, upon the earliest to occur of the maturity date, the acceleration of the Four 2022 Loans, and the prepayment, refinancing, substitution, or replacement of the Four 2022 Loans. We may voluntarily prepay all amounts outstanding under the Four 2022 Loans, subject to a prepayment premium of (i) 3% of the outstanding principal amount of the Four 2022 Loans if prepaid prior to or on October 17, 2024, (ii) 2% of the outstanding principal amount of the Four 2022 Loans if prepaid after October 17, 2024 through and including October 17, 2025, or (iii) 1% of the outstanding principal amount of the Four 2022 Loans if prepaid after October 17, 2025 and prior to the maturity date. The Four 2022 Loans are secured by substantially all of our assets, except for our intellectual property and certain other customary exclusions. Additionally, as discussed in Note 9. Derivative Liabilities , in connection with the 2022 Original Loans, we entered into an agreement whereby we agreed to pay an exit fee in the amount of 2% of the 2022 Original Loans funded (2022 Exit Fee). Notwithstanding the prepayment or termination of the 2022 Loan, the 2022 Exit Fee will expire 10 years from the Closing Date. The 2022 Loan Agreement, as amended, contains customary representations and warranties and customary affirmative and negative covenants, including, among others, requirements as to financial reporting and insurance and restrictions on our ability to dispose of our business or property, to change our line of business, to liquidate or dissolve, to enter into any change in control transaction, to merge or consolidate with any other entity or to acquire all or substantially all the capital stock or property of another entity, to incur additional indebtedness, to incur liens on our property, to pay any dividends or other distributions on capital stock other than dividends payable solely in capital stock or to redeem capital stock. We have agreed to not allow our cash, cash equivalents and available-for-sale investments to be less than the eighty percent (80%) of the outstanding Four 2022 Term Loan balance for any period in which our net revenue from the sale of any products, calculated on a trailing six (6) month basis and tested monthly, is less than sixty percent (60%) of the outstanding Four 2022 Loan balance. In addition, the 2022 Loan Agreement, as amended, contains customary events of default that entitle the Agent to cause our indebtedness under the 2022 Loan Agreement to become immediately due and payable, and to exercise remedies against us and the collateral securing the Four 2022 Term Loans, including our cash. Under the 2022 Loan Agreement, an event of default will occur if, among other things, we fail to make payments under the 2022 Loan Agreement, we breach any of our covenants under the 2022 Loan Agreement, subject to specified cure periods with respect to certain breaches, certain Lenders determine that a material adverse change has occurred, we or our assets become subject to certain legal proceedings, such as bankruptcy proceedings, we are unable to pay our debts as they become due or we default on contracts with third parties which would permit the holder of indebtedness to accelerate the maturity of such indebtedness or that could have a material adverse change on us. Upon the occurrence and for the duration of an event of default, an additional default interest rate equal to 4% per annum will apply to all obligations owed under the 2022 Loan Agreement. We have classified the 2022 Original Loan balance as a non-current liability as of March 31, 2024 due to principal repayments beginning in January 2027. We have concluded that the provisions that could cause acceleration of the principal repayments are remote. As of March 31, 2024, our future payment obligations related to the 2022 Loan, excluding interest payments and the 2022 final fee, were as follows (in thousands): Total repayment obligations $ 104,950 Less: Unamortized discount and debt issuance costs (1,111) Less: Unaccreted value of final fee (4,005) Long-term debt 99,834 Less: Current portion of long-term debt — Long-term debt, net of current portion $ 99,834

Derivative Liabilities

Derivative Liabilities	3 Months Ended
	Mar. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Liabilities	DERIVATIVE LIABILITIES 2018 Exit Fee In May 2018, in connection with entering into the 2018 Loan Agreement, we entered into an agreement pursuant to which we agreed to pay $1.5 million in cash (2018 Exit Fee) upon any change of control transaction in respect of the Company or if we obtain both (i) U.S. FDA approval of XPHOZAH and (ii) U.S. FDA approval of IBSRELA, which was obtained on September 12, 2019 (2018 Exit Fee Agreement). Notwithstanding the February 2022 prepayment of the 2018 Loan, our obligation to pay the 2018 Exit Fee would have expired on May 16, 2028. We concluded that the 2018 Exit Fee was a freestanding derivative which should be accounted for at fair value on a recurring basis. In October 2023, we received approval from the U.S. FDA for XPHOZAH to reduce serum phosphorus in adults with chronic kidney disease (CKD) on dialysis as add-on therapy in patients who have an inadequate response to phosphate binders or who are intolerant of any dose of phosphate binder therapy. This triggered our obligation to pay the 2018 Exit Fee to the 2018 Lenders. Prior to our subsequent payment of the 2018 Exit Fee in October 2023, the estimated fair value of the 2018 Exit Fee was recorded as a derivative liability and included in accrued expense and other current liabilities on the accompanying condensed balance sheets. 2022 Exit Fee In February 2022, in connection with entering into the 2022 Original Loans, we entered into an agreement, whereby we agreed to pay an exit fee in the amount of 2% of the 2022 Original Loan funded (2022 Exit Fee) upon (i) any change of control transaction or (ii) our achievement of net revenue from the sale of any products equal to or greater than $100.0 million, measured on a six (6) months basis (Revenue Milestone), tested monthly at the end of each month. The Term C and Term D Loans do not result in payment of an additional exit fee. Notwithstanding the prepayment or termination of the 2022 Loan, the 2022 Exit Fee will expire on February 23, 2032. We concluded that the 2022 Exit Fee is a freestanding derivative which should be accounted for at fair value on a recurring basis. The estimated fair value of the 2022 Exit Fee is recorded as a derivative liability and included in accrued expenses and other current liabilities on the accompanying condensed balance sheets. As of March 31, 2024 and December 31, 2023, the estimated fair value of the 2022 Exit Fee was $0.8 million and $0.7 million, respectively. The fair value of the derivative liability was determined using a discounted cash flow analysis and is classified as a Level 3 measurement within the fair value hierarchy since our valuation utilized significant unobservable inputs. Specifically, the key assumptions included in the calculation of the estimated fair value of the 2022 Exit Fee derivative liability include: (i) our estimates of both the probability and timing of achieving the Revenue Milestone and (ii) the probability and timing of funding the Term B Loan, which was dependent upon (a) approval by the U.S. FDA for our NDA for the control of serum phosphorus in adult patients with CKD on dialysis by November 30, 2023, and (b) achievement of certain product revenue milestone targets. As of March 31, 2024, uncertainty around two of the noted valuation estimates had been removed, as the Term B Loan had been funded and the U.S. FDA had approved our NDA for the control of serum phosphorus in adult patients with CKD on dialysis prior to November 30, 2023. Generally, increases or decreases in the probability of occurrence would result in a directionally similar impact in the fair value measurement of the derivative liability and it is estimated that a 10% increase (decrease) in the probability of occurrence would not result in a material fair value fluctuation. Changes in the fair value of recurring measurements included in Level 3 of the fair value hierarchy are presented as other income, net in our condensed statements of operations and comprehensive loss and were as follows for the three months ended March 31, 2024 and 2023 (in thousands): 2024 2023 Fair value of exit fee derivative liabilities at January 1, $ 675 $ 1,656 Changes in estimated fair value: 2018 Exit Fee — 48 2022 Exit Fee 159 22 Fair value of exit fee derivative liabilities at March 31, $ 834 $ 1,726

Leases

Leases	3 Months Ended
	Mar. 31, 2024
Leases [Abstract]
Leases	LEASES All of our leases are operating leases and each contain customary rent escalation clauses. Certain of the leases have both lease and non-lease components. We have elected to account for each separate lease component and the non-lease components associated with that lease component as a single lease component for all classes of underlying assets. The following table provides additional details of our facility leases presented in our condensed balance sheets (dollars in thousands): Facilities March 31, 2024 December 31, 2023 Right-of-use assets $ 4,641 $ 5,589 Current portion of lease liabilities 4,314 4,435 Operating lease liability, net of current portion 778 1,725 Total lease liabilities $ 5,092 $ 6,160 Weighted-average remaining life (years) 1.3 1.6 Weighted-average discount rate 6.8 % 6.8 % The lease costs, which are included in operating expenses in our condensed statements of operations and comprehensive loss, were as follows (in thousands): Three Months Ended March 31, 2024 2023 Operating lease expense $ 1,046 $ 1,064 Cash paid for operating lease $ 1,166 $ 1,098 The following table summarizes our undiscounted cash payment obligations for our operating lease liabilities as of March 31, 2024 (in thousands): Remainder of 2024 $ 3,550 2025 1,450 2026 329 Thereafter — Total undiscounted operating lease payments 5,329 Imputed interest expenses (237) Total operating lease liabilities 5,092 Less: Current portion of operating lease liability (4,314) Operating lease liability, net of current portion $ 778

Stockholders' Equity

Stockholders' Equity	3 Months Ended
	Mar. 31, 2024
Stockholders' Equity Note [Abstract]
Stockholders' Equity	STOCKHOLDERS’ EQUITY At the Market Offerings Agreement In July 2020, we filed a Form S-3 registration statement, which became effective in August 2020 (2020 Registration Statement). In August 2021, we filed a prospectus supplement under the 2020 Registration Statement for the offering, issuance and sale by us of up to a maximum aggregate offering price of $150.0 million of our common stock that may be issued and sold, from time to time, under a sales agreement (2021 Open Market Sales Agreement) we entered into with Jefferies LLC (Jefferies), pursuant to which we may, from time to time, sell up to $150.0 million in shares of our common stock through Jefferies. Pursuant to the 2021 Open Market Sales Agreement, Jefferies, as our sales agent, receives a commission of up to 3.0% of the gross sales price for shares of common stock sold under the 2021 Open Market Sales Agreement. As of March 2023, we had received the maximum gross proceeds of $150.0 million under the 2021 Open Market Sales Agreement at a weighted average share price of approximately $1.57 per share, which included 15.5 million shares of our common stock for which we received gross proceeds of $51.9 million at a weighted average share price of approximately $3.35 during the quarter ended March 31, 2023.

Equity Incentive Plans

Equity Incentive Plans	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Equity Incentive Plans	EQUITY INCENTIVE PLANS Stock-Based Compensation Stock-based compensation expense recognized for stock options, restricted stock units (RSUs), and our employee stock purchase program (ESPP) are recorded as operating expenses in our condensed statements of operations and comprehensive loss, as follows (in thousands): Three Months Ended March 31, 2024 2023 Selling, general and administrative $ 5,646 $ 2,088 Research and development 1,970 824 Total $ 7,616 $ 2,912 As of March 31, 2024, our total unrecognized stock-based compensation expense, net of estimated forfeitures, and average remaining vesting period, included the following (dollars in thousands): Unrecognized Compensation Expense Average Remaining Vesting Period (Years) Stock option grants $ 59,367 3.1 RSU grants $ 49,955 3.3 ESPP $ 522 0.4 Stock Options A summary of our stock option activity and related information for the three months ended March 31, 2024 is as follows (in thousands, except dollar amounts): Number of Shares Weighted-Average Balance at December 31, 2023 22,168 $ 4.20 Options granted 6,502 $ 8.68 Options exercised (702) $ 3.11 Options forfeited or canceled (178) $ 2.83 Balance at March 31, 2024 27,790 $ 5.29 Exercisable at March 31, 2024 12,856 $ 5.29 Restricted Stock Units A summary of our RSUs activity and related information for the three months ended March 31, 2024 is as follows (in thousands, except dollar amounts): Number of Weighted-Average Non-vested restricted stock units at December 31, 2023 3,646 $ 3.09 Granted 4,901 $ 8.68 Vested (552) $ 5.62 Forfeited (60) $ 2.64 Non-vested restricted stock units at March 31, 2024 7,935 $ 6.37 Employee Stock Purchase Plan During the three months ended March 31, 2024, we sold approximately 0.3 million shares of our common stock under the ESPP. The shares were purchased by employees at an average purchase price of $4.10 per share resulting in proceeds to us of approximately $1.0 million. Issuance of Common Stock for Services

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Net Loss Per Share	NET LOSS PER SHARE Basic net loss per share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period and excludes any dilutive effects of stock-based awards and warrants. Diluted net loss per common share is computed giving effect to all potential dilutive common shares, including common stock issuable upon exercise of stock options, and unvested restricted common stock and stock units. As we had net losses for the three months ended March 31, 2024 and 2023, all potential common shares were determined to be anti-dilutive. The following table sets forth the computation of net loss per common share (in thousands, except per share amounts): Three Months Ended March 31, Numerator: 2024 2023 Net loss $ (26,518) $ (26,773) Denominator: Weighted average common shares outstanding - basic 233,066 207,023 Weighted average common shares outstanding - diluted 233,066 207,023 Net loss per share of common stock - basic and diluted $ (0.11) $ (0.13) For the periods presented, the total numbers of securities that could potentially dilute net income per share in the future that were not considered in the diluted net loss per share calculations because the effect would have been anti-dilutive were as follows (in thousands): Three Months Ended March 31, 2024 2023 Options to purchase common stock 26,681 19,855 Restricted stock units 7,024 2,931 ESPP shares issuable 227 205 Total 33,932 22,991

Contingencies

Contingencies	3 Months Ended
	Mar. 31, 2024
Commitments and Contingencies Disclosure [Abstract]
Contingencies	CONTINGENCIES On July 30 and August 12, 2021, two putative securities class action lawsuits were commenced in the U.S. District Court for the Northern District of California naming as defendants Ardelyx and two current officers captioned Strezsak v. Ardelyx, Inc., et al. , Case No. 4:21-cv-05868-HSG, and Siegel v. Ardelyx, Inc., et al. , Case No. 5:21-cv-06228-HSG (together, the Securities Class Actions). The complaints allege that the defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 thereunder, by making false and misleading statements and omissions of material fact related to tenapanor. The plaintiffs seek damages and interest, and an award of costs, including attorneys’ fees. On July 19, 2022, the court consolidated the two putative class actions and appointed a lead plaintiff and lead counsel. The lead plaintiff filed a second amended complaint under which the plaintiffs seek to represent all persons who purchased or otherwise acquired Ardelyx securities between March 6, 2020 and July 19, 2021. Defendants filed a motion to dismiss the amended complaint on June 2, 2023. On March 22, 2024, the court granted defendants’ motion to dismiss. The court provided plaintiffs a third opportunity to amend and plaintiffs filed a third amended complaint on April 19, 2024. Defendant's motion to dismiss the third amended complaint is required to be filed by June 3, 2024. We believe the plaintiff’s claims are without merit and we have not recorded any accrual for a contingent liability associated with these legal proceedings. On December 7, 2021 and March 29, 2022, two verified shareholders derivative lawsuits were filed in the U.S. District Court for the Northern District of California purportedly on behalf of Ardelyx against certain of Ardelyx’s executive officers and members of our board of directors, captioned Go v. Raab , et al., Case No. 4:21-cv-09455-HSG, and Morris v. Raab , et al., Case No. 4:22-cv-01988-JSC. The complaints allege that the defendants' violations of Section 14(a) of the Securities Exchange Act of 1934, as amended, breaches of fiduciary duties, unjust enrichment, abuse of control, gross mismanagement, and waste of corporate assets for personally making and/or causing Ardelyx to make materially false and misleading statements regarding the Company’s business, operations and prospects. The complaint seeks contribution under Sections 10(b) and 21D of the Securities Exchange Act of 1934 from two executive officers. On January 19, and April 27, 2022, the court granted the parties’ stipulation to stay the Go and Morris actions, respectively, until resolution of the anticipated motion(s) to dismiss in the Securities Class Actions. On October 25, 2022, the parties filed a stipulation to consolidate and stay the Go and Morris actions, and on October 27, 2022, the court consolidated the Go and Morris action and stayed the consolidated action pending resolution of the anticipated motion(s) to dismiss in the Securities Class Action. We believe the plaintiff’s claims are without merit and we have not recorded any accrual for a contingent liability associated with these legal proceedings. From time to time, we may be involved in legal proceedings arising in the ordinary course of business. As of March 31, 2024, there is no litigation pending that would reasonably be expected to have a material adverse effect on our results of operations and financial condition, and no contingent liabilities were accrued as of March 31, 2024.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss) Attributable to Parent	$ (26,518)	$ (26,773)

Insider Trading Arrangements

Insider Trading Arrangements	3 Months Ended
	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Organization and Basis of Pre_2

Organization and Basis of Presentation (Policies)	3 Months Ended
	Mar. 31, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation These condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) and pursuant to the requirements of the Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules and regulations, certain footnotes or other financial information that are normally required by U.S. GAAP have been condensed or omitted. These condensed financial statements have been prepared on the same basis as our most recent annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments necessary to present fairly our financial position, results of operations, changes in stockholders’ equity, and cash flows for the interim periods presented. The accompanying condensed financial statements and related financial information should be read in conjunction with the audited financial statements and the related notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2023. The results for the three months ended March 31, 2024 are not necessarily indicative of results to be expected for the entire year ending December 31, 2024, or for any other interim period or future year.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes thereto. On an ongoing basis, management evaluates its estimates, including those related to recognition of revenue, clinical trial accruals, contract manufacturing accruals, expected demand for inventory, fair value of assets and liabilities, income taxes and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could materially differ from those estimates.
Recent Accounting Pronouncements	Recent Accounting Pronouncements New Accounting Pronouncements - Recently Adopted We have adopted no new accounting pronouncements subsequent to filing our most recent Annual Report on Form 10-K. Recent Accounting Pronouncements Not Yet Adopted In October 2023, the Financial Accounting Standards Board (FASB) issued ASU No. 2023-06, Disclosure Improvements - Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative. The amendments in this Update modify the disclosure or presentation requirements of a variety of Topics in the Codification. The amendments are in response to the U.S. Securities and Exchange Commission's (SEC) Release No. 33-10532, Disclosure Update and Simplification, in which the SEC referred certain of its disclosure requirements that overlap with, but require incremental information to, generally accepted accounting principles to the FASB for potential incorporation into the Codification. For entities subject to the SEC’s existing disclosure requirements and for entities required to file or furnish financial statements with or to the SEC in preparation for the sale of or for purposes of issuing securities that are not subject to contractual restrictions on transfer, the effective date for each amendment will be the date on which the SEC’s removal of that related disclosure from Regulation S-X or Regulation S-K becomes effective, with early adoption prohibited. For all other entities, the amendments will be effective two years later. For all entities, if by June 30, 2027, the SEC has not removed the applicable requirement from Regulation S-X or Regulation S-K, the pending content of the related amendment will be removed from the Codification and will not become effective for any entity. Management is currently assessing the impact of this standard on the Company’s financial statements. In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280) - Improvements to Reportable Segment Disclosures. This Update requires publicly traded entities to provide enhanced disclosures about significant segment expenses regularly reviewed by the chief operating decision maker (CODM), including public traded entities with a single reportable segment. The amendments in this update are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption is permitted. Management is currently assessing the impact of this standard on the Company’s financial statements. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740) - Improvements to Income Tax Disclosures, an amendment which modifies the measurement and recognition of credit losses for most financial assets and certain other instruments. The amendments in this Update provide more transparency about income tax information through improvements to income tax disclosures primarily related to the rate reconciliation and income taxes paid information. For public business entities, the amendments in this Update are effective for annual periods beginning after December 15, 2024. Early adoption is permitted on a prospective basis for annual financial statements that have not yet been issued or made available for issuance. Management is currently assessing the impact of this standard on the Company’s financial statements. In March 2024, the FASB issued ASU No. 2024-02, Codification Improvements - Amendments to Remove References to the Concepts Statements, an amendment to the Codification which removes references to various FASB Concepts Statements. The amendments apply to all reporting entities within the scope of the affected accounting guidance, but in most instances the references removed are extraneous and not required to understand or apply the guidance. Generally, the amendments in ASU 2024-02 are not intended to result in significant accounting changes for most entities. The amendments in this update are effective for fiscal years beginning after December 15, 2024 and are not expected to have a significant impact on our financial statements.
Fair Value Measurements	The three-level hierarchy for the inputs to valuation techniques is briefly summarized as follows: Level 1 – Valuations are based on quoted prices in active markets for identical assets or liabilities and readily accessible by us at the reporting date. Level 2 – Valuations based on inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Valuations based on unobservable inputs for which there is little or no market data, which require us to develop our own assumptions. Where quoted prices are available in an active market, securities are classified as Level 1. We classify money market funds as Level 1. When quoted market prices are not available for the specific security, we estimate fair value by using benchmark yields, reported trades, broker/dealer quotes and issuer spreads. We classify U.S. government-sponsored agency bonds, U.S. treasury securities, corporate bonds, commercial paper, and asset-backed securities as Level 2. In certain cases, where there is limited activity or less transparency around inputs to valuation, securities or derivative liabilities, such as the 2022 Exit Fee, as defined and discussed in Note 9. Derivative Liabilities , are classified as Level 3. The carrying amounts reflected in the condensed balance sheets for accounts receivable, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values at both March 31, 2024 and December 31, 2023, due to their short-term nature. Based on our procedures under the expected credit loss model, including an assessment of unrealized losses in our portfolio, we concluded that any unrealized losses on our marketable securities were not attributable to credit and, therefore, we have not recorded an allowance for credit losses for these securities as of March 31, 2024 and December 31, 2023. Fair Value of Debt The principal amount outstanding under our term loan facilities is subject to a variable interest rate. Therefore, we believe the carrying amount of the term loan facility approximates fair value as of March 31, 2024 and December 31, 2023. See Note 8. Borrowing for a description of the Level 2 inputs used to estimate the fair value of the liability. The carrying value of the deferred royalty obligation related to the sale of future royalties approximates its fair value as of March 31, 2024 and December 31, 2023 and is based on our current estimates of future royalties and commercialization milestones expected to be paid to us by Kyowa Kirin Co., Ltd. (Kyowa Kirin) over the life of the agreement. See Note 7. Deferred Royalty Obligation Related to the Sale of Future Royalties for a description of the Level 3 inputs used to estimate the fair value of the liability.

Cash, Cash Equivalents and In_2

Cash, Cash Equivalents and Investments (Tables)	3 Months Ended
	Mar. 31, 2024
Cash and Cash Equivalents [Abstract]
Schedule of Securities Classified as Cash, Cash Equivalents and Investments	Securities classified as cash, cash equivalents and short-term investments as of March 31, 2024 and December 31, 2023 are summarized below (in thousands): March 31, 2024 Gross Unrealized Amortized Cost Gains Losses Fair Value Cash and cash equivalents: Cash $ 3,844 $ — $ — $ 3,844 Money market funds 32,303 — — 32,303 Total cash and cash equivalents 36,147 — — 36,147 Short-term investments: U.S. government-sponsored agency bonds $ 101,706 $ 34 $ (23) $ 101,717 Commercial paper 53,549 11 (39) 53,521 Asset-backed securities 8,707 — (3) 8,704 U.S. treasury securities 2,489 — — 2,489 Total short-term investments 166,451 45 (65) 166,431 Total cash, cash equivalents and investments $ 202,598 $ 45 $ (65) $ 202,578 December 31, 2023 Gross Unrealized Amortized Cost Gains Losses Fair Value Cash and cash equivalents: Cash $ 2,829 $ — $ — $ 2,829 Money market funds 18,641 — — 18,641 Total cash and cash equivalents 21,470 — — 21,470 Short-term investments: U.S. government-sponsored agency bonds $ 101,892 $ 235 $ (34) $ 102,093 Commercial paper 49,630 41 (17) 49,654 Asset-backed securities 8,628 2 (5) 8,625 U.S. treasury securities 2,455 2 — 2,457 Total short-term investments 162,605 280 (56) 162,829 Total cash, cash equivalents and investments $ 184,075 $ 280 $ (56) $ 184,299

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2024
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Financial Assets and Liabilities Measured on a Recurring Basis	The following table sets forth the fair value of our financial assets and liabilities that are measured or disclosed on a recurring basis by level within the fair value hierarchy (in thousands): March 31, 2024 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 32,303 $ 32,303 $ — $ — U.S. government-sponsored agency bonds 101,717 — 101,717 — Commercial paper 53,521 — 53,521 — Asset-backed securities 8,704 — 8,704 — U.S. treasury securities 2,489 — 2,489 — Total $ 198,734 $ 32,303 $ 166,431 $ — Liabilities: Derivative liabilities for exit fee $ 834 $ — $ — $ 834 Total $ 834 $ — $ — $ 834 December 31, 2023 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 18,641 $ 18,641 $ — $ — U.S. government-sponsored agency bonds 102,093 — 102,093 — Commercial paper 49,654 — 49,654 — Asset-backed securities 8,625 — 8,625 — U.S. treasury securities 2,457 — 2,457 — Total $ 181,470 $ 18,641 $ 162,829 $ — Liabilities: Derivative liability for exit fees $ 675 $ — $ — $ 675 Total $ 675 $ — $ — $ 675

Inventory (Tables)

Inventory (Tables)	3 Months Ended
	Mar. 31, 2024
Inventory Disclosure [Abstract]
Schedule of Current Inventory	Inventory as of March 31, 2024 and December 31, 2023 consisted of the following (in thousands): March 31, 2024 December 31, 2023 Raw materials $ 20,906 $ 22,920 Work in process 54,206 24,582 Finished goods 3,746 1,985 Total $ 78,858 $ 49,487 Reported as: Inventory $ 9,813 $ 12,448 Inventory, non-current 69,045 37,039 Total $ 78,858 $ 49,487
Schedule of Noncurrent Inventory	Inventory as of March 31, 2024 and December 31, 2023 consisted of the following (in thousands): March 31, 2024 December 31, 2023 Raw materials $ 20,906 $ 22,920 Work in process 54,206 24,582 Finished goods 3,746 1,985 Total $ 78,858 $ 49,487 Reported as: Inventory $ 9,813 $ 12,448 Inventory, non-current 69,045 37,039 Total $ 78,858 $ 49,487

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2024
Revenue from Contract with Customer [Abstract]
Schedule of Revenue	Total revenues during the three months ended March 31, 2024 and 2023 were as follows (in thousands): Three Months Ended March 31, 2024 2023 Product sales, net: IBSRELA $ 28,361 $ 11,355 XPHOZAH 15,151 — Total product sales, net 43,512 11,355 Product supply revenue 2,126 2 Licensing revenue 17 12 Non-cash royalty revenue related to the sale of future royalties 368 — Total revenues $ 46,023 $ 11,369
Schedule of Revenue from Customers as a Percentage of Total Product Revenue, Net	Revenue from Customers who contributed greater than 10% of our total gross product revenue during the three months ended March 31, 2024 and 2023 was as follows (as a percentage of total gross product revenue): Three Months Ended March 31, 2024 2023 BioRidge Pharma, LLC 39.9 % 17.6 % AmerisourceBergen Drug Corporation 18.3 % 21.6 % Cardinal Health 16.2 % 22.2 % McKesson Corporation 13.5 % 20.8 %
Schedule of Chargebacks, Discounts and Reserve Balances	The activities and ending reserve balances for each significant category of discounts and allowances, which constitute variable consideration, were as follows (in thousands): Discounts and Chargebacks Rebates, Wholesaler and GPO Fees Copay and Returns Total Balance as of December 31, 2023 $ 478 $ 4,234 $ 3,916 $ 8,628 Provisions 2,644 9,525 6,846 19,015 Credits/payments (2,467) (7,211) (3,852) (13,530) Balance as of March 31, 2024 $ 655 $ 6,548 $ 6,910 $ 14,113

Collaboration and Licensing A_2

Collaboration and Licensing Agreements (Tables)	3 Months Ended
	Mar. 31, 2024
Collaboration and Licensing Agreements
Schedule of Deferred Revenue Balances	The following tables present changes in our current and non-current deferred revenue balances during the reporting period, which are all attributable to the 2017 Kyowa Kirin Agreement (in thousands): 2024 2023 Current Non-Current Current Non-Current Balance at January 1, $ 7,182 $ 8,644 $ 4,211 $ 9,025 Amounts invoiced as prepayments for product supply 732 3,459 525 3,282 Decrease for revenue recognized for product supply (1,328) — — — Reclassify amounts to be recognized in the next twelve months — — 809 (809) Balance at March 31, $ 6,586 $ 12,103 $ 5,545 $ 11,498

Borrowing (Tables)

Borrowing (Tables)	3 Months Ended
	Mar. 31, 2024
Debt Disclosure [Abstract]
Schedule of Future Debt Payment Obligations	As of March 31, 2024, our future payment obligations related to the 2022 Loan, excluding interest payments and the 2022 final fee, were as follows (in thousands): Total repayment obligations $ 104,950 Less: Unamortized discount and debt issuance costs (1,111) Less: Unaccreted value of final fee (4,005) Long-term debt 99,834 Less: Current portion of long-term debt — Long-term debt, net of current portion $ 99,834

Derivative Liabilities (Tables)

Derivative Liabilities (Tables)	3 Months Ended
	Mar. 31, 2024
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Changes in Fair Value of Derivative Liability	Changes in the fair value of recurring measurements included in Level 3 of the fair value hierarchy are presented as other income, net in our condensed statements of operations and comprehensive loss and were as follows for the three months ended March 31, 2024 and 2023 (in thousands): 2024 2023 Fair value of exit fee derivative liabilities at January 1, $ 675 $ 1,656 Changes in estimated fair value: 2018 Exit Fee — 48 2022 Exit Fee 159 22 Fair value of exit fee derivative liabilities at March 31, $ 834 $ 1,726

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2024
Leases [Abstract]
Schedule of Additional Details of Leases	The following table provides additional details of our facility leases presented in our condensed balance sheets (dollars in thousands): Facilities March 31, 2024 December 31, 2023 Right-of-use assets $ 4,641 $ 5,589 Current portion of lease liabilities 4,314 4,435 Operating lease liability, net of current portion 778 1,725 Total lease liabilities $ 5,092 $ 6,160 Weighted-average remaining life (years) 1.3 1.6 Weighted-average discount rate 6.8 % 6.8 %
Schedule of Lease Costs	The lease costs, which are included in operating expenses in our condensed statements of operations and comprehensive loss, were as follows (in thousands): Three Months Ended March 31, 2024 2023 Operating lease expense $ 1,046 $ 1,064 Cash paid for operating lease $ 1,166 $ 1,098
Schedule of Undiscounted Cash Payment Obligations for Operating Lease Liabilities	The following table summarizes our undiscounted cash payment obligations for our operating lease liabilities as of March 31, 2024 (in thousands): Remainder of 2024 $ 3,550 2025 1,450 2026 329 Thereafter — Total undiscounted operating lease payments 5,329 Imputed interest expenses (237) Total operating lease liabilities 5,092 Less: Current portion of operating lease liability (4,314) Operating lease liability, net of current portion $ 778

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	3 Months Ended
	Mar. 31, 2024
Share-Based Payment Arrangement [Abstract]
Schedule of Stock-Based Compensation Expense Recognized	Stock-based compensation expense recognized for stock options, restricted stock units (RSUs), and our employee stock purchase program (ESPP) are recorded as operating expenses in our condensed statements of operations and comprehensive loss, as follows (in thousands): Three Months Ended March 31, 2024 2023 Selling, general and administrative $ 5,646 $ 2,088 Research and development 1,970 824 Total $ 7,616 $ 2,912
Schedule of Total Unrecognized Stock-Based Compensation Expense, Net of Estimated Forfeitures	As of March 31, 2024, our total unrecognized stock-based compensation expense, net of estimated forfeitures, and average remaining vesting period, included the following (dollars in thousands): Unrecognized Compensation Expense Average Remaining Vesting Period (Years) Stock option grants $ 59,367 3.1 RSU grants $ 49,955 3.3 ESPP $ 522 0.4
Schedule of Stock Option Activity	A summary of our stock option activity and related information for the three months ended March 31, 2024 is as follows (in thousands, except dollar amounts): Number of Shares Weighted-Average Balance at December 31, 2023 22,168 $ 4.20 Options granted 6,502 $ 8.68 Options exercised (702) $ 3.11 Options forfeited or canceled (178) $ 2.83 Balance at March 31, 2024 27,790 $ 5.29 Exercisable at March 31, 2024 12,856 $ 5.29
Schedule of Restricted Stock Units Activity	A summary of our RSUs activity and related information for the three months ended March 31, 2024 is as follows (in thousands, except dollar amounts): Number of Weighted-Average Non-vested restricted stock units at December 31, 2023 3,646 $ 3.09 Granted 4,901 $ 8.68 Vested (552) $ 5.62 Forfeited (60) $ 2.64 Non-vested restricted stock units at March 31, 2024 7,935 $ 6.37

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2024
Earnings Per Share [Abstract]
Schedule of Computation of Net Loss Per Common Share	The following table sets forth the computation of net loss per common share (in thousands, except per share amounts): Three Months Ended March 31, Numerator: 2024 2023 Net loss $ (26,518) $ (26,773) Denominator: Weighted average common shares outstanding - basic 233,066 207,023 Weighted average common shares outstanding - diluted 233,066 207,023 Net loss per share of common stock - basic and diluted $ (0.11) $ (0.13)
Schedule of Anti-Dilutive Securities Not Considered in Diluted Net Loss Per Common Share Calculation	For the periods presented, the total numbers of securities that could potentially dilute net income per share in the future that were not considered in the diluted net loss per share calculations because the effect would have been anti-dilutive were as follows (in thousands): Three Months Ended March 31, 2024 2023 Options to purchase common stock 26,681 19,855 Restricted stock units 7,024 2,931 ESPP shares issuable 227 205 Total 33,932 22,991

Organization and Basis of Pre_3

Organization and Basis of Presentation (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($) segment	Dec. 31, 2023 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of segments | segment	1
Cash and short-term investments	$ 202,578	$ 184,299
Accumulated deficit	$ 872,722	$ 846,204

Cash, Cash Equivalents and In_3

Cash, Cash Equivalents and Investments - Securities Classified as Cash, Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Cash and cash equivalents:
Fair Value	$ 36,147	$ 21,470
Short-term investments:
Amortized Cost	166,451	162,605
Gross Unrealized Gains	45	280
Gross Unrealized Losses	(65)	(56)
Fair Value	166,431	162,829
Total cash equivalents and investments, Amortized Cost	202,598	184,075
Total cash equivalents and investments, Gross Unrealized Gains	45	280
Total cash equivalents and investments, Gross Unrealized Losses	(65)	(56)
Cash and short-term investments	202,578	184,299
U.S. government-sponsored agency bonds
Short-term investments:
Amortized Cost	101,706	101,892
Gross Unrealized Gains	34	235
Gross Unrealized Losses	(23)	(34)
Fair Value	101,717	102,093
Commercial paper
Short-term investments:
Amortized Cost	53,549	49,630
Gross Unrealized Gains	11	41
Gross Unrealized Losses	(39)	(17)
Fair Value	53,521	49,654
Asset-backed securities
Short-term investments:
Amortized Cost	8,707	8,628
Gross Unrealized Gains	0	2
Gross Unrealized Losses	(3)	(5)
Fair Value	8,704	8,625
U.S. treasury securities
Short-term investments:
Amortized Cost	2,489	2,455
Gross Unrealized Gains	0	2
Gross Unrealized Losses	0	0
Fair Value	2,489	2,457
Cash
Cash and cash equivalents:
Fair Value	3,844	2,829
Money market funds
Cash and cash equivalents:
Fair Value	$ 32,303	$ 18,641

Cash, Cash Equivalents and In_4

Cash, Cash Equivalents and Investments - Narrative (Details) - investment	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Cash and Cash Equivalents [Abstract]
Short-term securities, contractual maturities maximum (in years)	1 year	1 year
Investment in continuous unrealized loss position for more than one year	0	0

Fair Value Measurements - Finan

Fair Value Measurements - Financial Assets and Liabilities Measured on a Recurring Basis (Details) - Recurring - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Assets:
Assets, fair value	$ 198,734	$ 181,470
Liabilities:
Liabilities, fair value	834	675
Derivative liabilities for exit fee
Liabilities:
Liabilities, fair value	834	675
Level 1
Assets:
Assets, fair value	32,303	18,641
Liabilities:
Liabilities, fair value	0	0
Level 1 | Derivative liabilities for exit fee
Liabilities:
Liabilities, fair value	0	0
Level 2
Assets:
Assets, fair value	166,431	162,829
Liabilities:
Liabilities, fair value	0	0
Level 2 | Derivative liabilities for exit fee
Liabilities:
Liabilities, fair value	0	0
Level 3
Assets:
Assets, fair value	0	0
Liabilities:
Liabilities, fair value	834	675
Level 3 | Derivative liabilities for exit fee
Liabilities:
Liabilities, fair value	834	675
Money market funds
Assets:
Assets, fair value	32,303	18,641
Money market funds | Level 1
Assets:
Assets, fair value	32,303	18,641
Money market funds | Level 2
Assets:
Assets, fair value	0	0
Money market funds | Level 3
Assets:
Assets, fair value	0	0
U.S. government-sponsored agency bonds
Assets:
Assets, fair value	101,717	102,093
U.S. government-sponsored agency bonds | Level 1
Assets:
Assets, fair value	0	0
U.S. government-sponsored agency bonds | Level 2
Assets:
Assets, fair value	101,717	102,093
U.S. government-sponsored agency bonds | Level 3
Assets:
Assets, fair value	0	0
Commercial paper
Assets:
Assets, fair value	53,521	49,654
Commercial paper | Level 1
Assets:
Assets, fair value	0	0
Commercial paper | Level 2
Assets:
Assets, fair value	53,521	49,654
Commercial paper | Level 3
Assets:
Assets, fair value	0	0
Asset-backed securities
Assets:
Assets, fair value	8,704	8,625
Asset-backed securities | Level 1
Assets:
Assets, fair value	0	0
Asset-backed securities | Level 2
Assets:
Assets, fair value	8,704	8,625
Asset-backed securities | Level 3
Assets:
Assets, fair value	0	0
U.S. treasury securities
Assets:
Assets, fair value	2,489	2,457
U.S. treasury securities | Level 1
Assets:
Assets, fair value	0	0
U.S. treasury securities | Level 2
Assets:
Assets, fair value	2,489	2,457
U.S. treasury securities | Level 3
Assets:
Assets, fair value	$ 0	$ 0

Fair Value Measurements - Narra

Fair Value Measurements - Narrative (Details) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Allowance for credit loss on available for-sale debt securities	$ 0	$ 0

Inventory - Schedule of Invento

Inventory - Schedule of Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Inventory Disclosure [Abstract]
Raw materials	$ 20,906	$ 22,920
Work in process	54,206	24,582
Finished goods	3,746	1,985
Inventory	9,813	12,448
Inventory, non-current	69,045	37,039
Total	$ 78,858	$ 49,487

Inventory - Narrative (Details)

Inventory - Narrative (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Inventory Disclosure [Abstract]
Prepaid commercial manufacturing	$ 9,800	$ 23,200
Prepaid commercial manufacturing, non-current	$ 4,235	$ 4,235

Revenue - Schedule of Revenue (

Revenue - Schedule of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Total revenues	$ 46,023	$ 11,369
Product sales, net
Disaggregation of Revenue [Line Items]
Total revenues	43,512	11,355
IBSRELA
Disaggregation of Revenue [Line Items]
Total revenues	28,361	11,355
XPHOZAH
Disaggregation of Revenue [Line Items]
Total revenues	15,151	0
Product supply revenue
Disaggregation of Revenue [Line Items]
Total revenues	2,126	2
Licensing revenue
Disaggregation of Revenue [Line Items]
Total revenues	17	12
Non-cash royalty revenue related to the sale of future royalties
Disaggregation of Revenue [Line Items]
Total revenues	$ 368	$ 0

Revenue - Revenue from Customer

Revenue - Revenue from Customers as a Percentage of Total Product Revenue, Net (Details) - Gross product revenue - Customer	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
BioRidge Pharma, LLC
Disaggregation of Revenue [Line Items]
Concentration risk (as percent)	39.90%	17.60%
AmerisourceBergen Drug Corporation
Disaggregation of Revenue [Line Items]
Concentration risk (as percent)	18.30%	21.60%
Cardinal Health
Disaggregation of Revenue [Line Items]
Concentration risk (as percent)	16.20%	22.20%
McKesson Corporation
Disaggregation of Revenue [Line Items]
Concentration risk (as percent)	13.50%	20.80%

Revenue - Chargebacks, Discount

Revenue - Chargebacks, Discounts and Reserve Balances (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
Gross-to-net sales accruals and reserves
Beginning balance	$ 8,628
Provisions	19,015
Credits/payments	(13,530)
Ending balance	14,113
Discounts and Chargebacks
Gross-to-net sales accruals and reserves
Beginning balance	478
Provisions	2,644
Credits/payments	(2,467)
Ending balance	655
Rebates, Wholesaler and GPO Fees
Gross-to-net sales accruals and reserves
Beginning balance	4,234
Provisions	9,525
Credits/payments	(7,211)
Ending balance	6,548
Copay and Returns
Gross-to-net sales accruals and reserves
Beginning balance	3,916
Provisions	6,846
Credits/payments	(3,852)
Ending balance	$ 6,910

Collaboration and Licensing A_3

Collaboration and Licensing Agreements - Narrative (Details) $ in Thousands, $ in Millions, ¥ in Billions

1 Months Ended

3 Months Ended

77 Months Ended

Dec. 31, 2017 USD ($)

Nov. 30, 2017 USD ($)

Jun. 30, 2015 USD ($)

Mar. 31, 2024 USD ($)

Mar. 31, 2024 CAD ($)

Mar. 31, 2023 USD ($)

Mar. 31, 2024 USD ($)

Mar. 31, 2024 JPY (¥)

Oct. 31, 2023 USD ($)

Sep. 30, 2023 USD ($)

Jul. 31, 2023 USD ($)

Oct. 31, 2022 USD ($)

Apr. 30, 2022 USD ($) payment_tranche

Mar. 31, 2018 USD ($)

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Total revenues

$ 46,023

$ 11,369

Licensing revenue

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Total revenues

17

12

Non-cash royalty revenue related to the sale of future royalties

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Total revenues

368

0

Product supply revenue

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Total revenues

2,126

2

2017 KKC Agreement | Non-cash royalty revenue related to the sale of future royalties

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Total revenues

400

2017 KKC Agreement | Product supply revenue

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Total revenues

2,100

2

Fosun Agreement | Licensing revenue

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Total revenues

0

0

Knight Agreement | Licensing revenue

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Total revenues

0

0

KKC | 2017 KKC Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Upfront license fees

$ 30,000

Potential development milestones

$ 55,000

Total revenues

$ 35,000

Potential commercialization milestones

56,200

56,200

¥ 8.5

Fee receivable for reduction in royalty rate

$ 40,000

Number of payment tranches for fee receivable for reduction in royalty rate | payment_tranche

2

KKC | 2017 KKC Agreement | Licensing revenue

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Proceeds from milestone payments

$ 30,000

$ 35,000

Fosun Pharma | Fosun Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Proceeds from milestone payments

8,000

8,000

$ 3,000

$ 2,000

Upfront payment received

$ 12,000

Potential development and commercialization milestones

$ 113,000

Threshold percentage of net sales for tiered royalties

20%

20%

Knight | Knight Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Potential development milestones

$ 700

700

Non-cash royalty revenue

$ 2,300

Potential development and commercialization milestones

16,300

$ 22.2

AstraZeneca | AZ Termination Agreement

Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]

Percentage of royalty revenue

10%

Percentage of non-royalty revenue

20%

Maximum potential payment per agreement

$ 75,000

Aggregate cost of revenue recognized

32,400

$ 32,400

Cost of revenue

$ 4,700

$ 1,200

Collaboration and Licensing A_4

Collaboration and Licensing Agreements - Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Current
Beginning balance	$ 7,182
Ending balance	6,586
Non-Current
Beginning balance	8,644
Ending balance	12,103
2017 KKC Agreement
Current
Beginning balance	7,182	$ 4,211
Amounts invoiced as prepayments for product supply	732	525
Decrease for revenue recognized for product supply	(1,328)	0
Reclassify amounts to be recognized in the next twelve months	0	809
Ending balance	6,586	5,545
Non-Current
Beginning balance	8,644	9,025
Amounts invoiced as prepayments for product supply	3,459	3,282
Decrease for revenue recognized for product supply	0	0
Reclassify amounts to be recognized in the next twelve months	0	(809)
Ending balance	$ 12,103	$ 11,498

Deferred Royalty Obligation R_2

Deferred Royalty Obligation Related To The Sale Of Future Royalties (Details) - USD ($)	1 Months Ended	3 Months Ended
	Jun. 30, 2022	Mar. 31, 2024	Mar. 31, 2023	Oct. 31, 2023
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Non-cash interest expense related to the sale of future royalties		$ 1,702,000	$ 969,000
Proceeds from royalties received		0
Healthcare royalty partners IV, L.P | License
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Royalty payments and commercial milestone payments	$ 20,000,000
Revenue to be received	10,000,000			$ 5,000,000
Payment to be received	$ 5,000,000			$ 5,000,000
Transaction costs		$ 400,000
Amortization, effective interest rate (as percent)		33.70%

Borrowing - Narrative (Details)

Borrowing - Narrative (Details) - USD ($)	Oct. 17, 2023	Feb. 23, 2022	Mar. 31, 2024	May 31, 2018
Debt Instrument [Line Items]
Principal outstanding			$ 104,950,000
2018 Exit Fee
Debt Instrument [Line Items]
Agreed amount for exit fee upon occurrence of certain conditions				$ 1,500,000
2022 Exit Fee
Debt Instrument [Line Items]
Exit fee (as percent)	2%
Exit fee, term (in years)	10 years
2018 Term Loan | Loan Agreement
Debt Instrument [Line Items]
Term loan face amount				$ 50,000,000
Principal outstanding		$ 25,000,000
2022 Term Loan | Loan Agreement
Debt Instrument [Line Items]
Final fee due upon maturity, acceleration, prepayment, or termination (as percent)		4.95%
Loan agreement covenant, cash and cash equivalents as percentage of outstanding loan balance, minimum		80%
Loan agreement, covenant, cash and cash equivalents as percentage of outstanding loan balance, calculation period (in months)		6 months
Loan agreement covenant, net product revenue as percentage of outstanding loan balance, minimum		60%
Additional default interest rate (as percent)		4%
2022 Term Loan | Loan Agreement | Prior to first anniversary of closing date
Debt Instrument [Line Items]
Prepayment premium (as percent)	3%
2022 Term Loan | Loan Agreement | After first anniversary through second anniversary of closing date
Debt Instrument [Line Items]
Prepayment premium (as percent)	2%
2022 Term Loan | Loan Agreement | After second anniversary to maturity date
Debt Instrument [Line Items]
Prepayment premium (as percent)	1%
Term Loan A | Loan Agreement
Debt Instrument [Line Items]
Proceeds from the sale of future royalties, net of issuance costs		$ 27,500,000
Interest rate (as percent)	7.95%
Closing fee	$ 200,000
Term Loan A | Loan Agreement | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Floating per annum rate (as percent)	0.022%
Term Loan A | Loan Agreement | Floor Rate
Debt Instrument [Line Items]
Floating per annum rate (as percent)	1%
Term Loan B | Loan Agreement
Debt Instrument [Line Items]
Remaining funding based on milestone achievement		22,500,000
Interest rate (as percent)	7.95%
Future obligation upon loan funding or other events		$ 100,000
Term Loan B | Loan Agreement | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Floating per annum rate (as percent)	0.022%
Term Loan B | Loan Agreement | Floor Rate
Debt Instrument [Line Items]
Floating per annum rate (as percent)	1%
Term Loan C | Loan Agreement
Debt Instrument [Line Items]
Additional committed capital	$ 50,000,000
Interest rate (as percent)	4.25%
Closing fee	$ 300,000
Term Loan C | Loan Agreement | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Floating per annum rate (as percent)	0.022%
Term Loan C | Loan Agreement | Floor Rate
Debt Instrument [Line Items]
Floating per annum rate (as percent)	4.70%
Term Loan D | Loan Agreement
Debt Instrument [Line Items]
Additional uncommitted capital	$ 50,000,000
Interest rate (as percent)	4.25%
Closing fee percentage	0.50%
Term Loan D | Loan Agreement | Secured Overnight Financing Rate (SOFR)
Debt Instrument [Line Items]
Floating per annum rate (as percent)	0.022%
Term Loan D | Loan Agreement | Floor Rate
Debt Instrument [Line Items]
Floating per annum rate (as percent)	4.70%

Borrowing - Future Debt Payment

Borrowing - Future Debt Payment Obligations (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Disclosure [Abstract]
Total repayment obligations	$ 104,950
Less: Unamortized discount and debt issuance costs	(1,111)
Less: Unaccreted value of final fee	(4,005)
Long-term debt	99,834
Less: Current portion of long-term debt	0
Long-term debt, net of current portion	$ 99,834	$ 49,822

Derivative Liabilities - Narrat

Derivative Liabilities - Narrative (Details) - USD ($) $ in Millions	1 Months Ended
	Feb. 28, 2022	Mar. 31, 2024	Dec. 31, 2023	Oct. 17, 2023	May 31, 2018
2018 Exit Fee
Derivative [Line Items]
Agreed amount for exit fee upon change of control or regulatory approval					$ 1.5
2022 Exit Fee
Derivative [Line Items]
Exit fee (as percent)				2%
Exit fee, net product revenue threshold	$ 100
Estimated fair value		$ 0.8	$ 0.7
2022 Exit Fee | Level 3
Derivative [Line Items]
Fair value analysis, percentage change in probability of occurrence		10%

Derivative Liabilities - Change

Derivative Liabilities - Changes in Fair Value of Derivative Liability (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
2022 Exit Fee
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 700
Ending balance	800
Exit Fee derivative liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	675	$ 1,656
Ending balance	834	1,726
Exit Fee derivative liability | 2018 Exit Fee
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in estimated fair value	0	48
Exit Fee derivative liability | 2022 Exit Fee
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Changes in estimated fair value	$ 159	$ 22

Leases - Additional Details of

Leases - Additional Details of Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Right-of-use assets and lease liabilities
Right-of-use assets	$ 4,641	$ 5,589
Current portion of lease liabilities	4,314	4,435
Operating lease liability, net of current portion	778	1,725
Total operating lease liabilities	$ 5,092	$ 6,160
Additional details
Weighted-average remaining life (years)	1 year 3 months 18 days	1 year 7 months 6 days
Weighted-average discount rate	6.80%	6.80%

Leases - Lease Costs (Details)

Leases - Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Lease costs
Operating lease expense	$ 1,046	$ 1,064
Cash paid for operating lease	$ 1,166	$ 1,098

Leases - Undiscounted Cash Paym

Leases - Undiscounted Cash Payment Obligations for Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Undiscounted cash payment obligations
Remainder of 2024	$ 3,550
2025	1,450
2026	329
Thereafter	0
Total undiscounted operating lease payments	5,329
Imputed interest expenses	(237)
Total operating lease liabilities	5,092	$ 6,160
Less: Current portion of operating lease liability	(4,314)	(4,435)
Operating lease liability, net of current portion	$ 778	$ 1,725

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, shares in Millions	1 Months Ended		3 Months Ended		20 Months Ended
	Jan. 31, 2023	Aug. 31, 2021	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2023
Subsidiary, Sale of Stock [Line Items]
Proceeds from issuance of common stock in at the market offering, net of issuance costs			$ 0	$ 50,719,000
2021 Open Market Sales Agreement
Subsidiary, Sale of Stock [Line Items]
Commission on sale of stock per agreement (as percent)		3%
Total of gross proceeds				$ 150,000,000	$ 150,000,000
Weighted-average sales price per share (in dollars per share)				$ 3.35	$ 1.57
Issuance of common stock in at the market offering (in shares)				15.5
Proceeds from issuance of common stock in at the market offering, net of issuance costs				$ 51,900,000
2023 Open Market Sales Agreement
Subsidiary, Sale of Stock [Line Items]
Commission on sale of stock per agreement (as percent)	3%
Weighted-average sales price per share (in dollars per share)			$ 4.17
Issuance of common stock in at the market offering (in shares)			16.8
Proceeds from issuance of common stock in at the market offering, net of issuance costs			$ 70,000,000
Common stock
Subsidiary, Sale of Stock [Line Items]
Maximum aggregate offering price	$ 250,000,000
Common stock | 2021 Open Market Sales Agreement
Subsidiary, Sale of Stock [Line Items]
Maximum aggregate offering price		$ 150,000,000
Common stock | 2023 Open Market Sales Agreement
Subsidiary, Sale of Stock [Line Items]
Maximum aggregate offering price	$ 150,000,000

Equity Incentive Plans - Stock-

Equity Incentive Plans - Stock-Based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Stock-based Compensation [Line Items]
Stock-based compensation expense	$ 7,616	$ 2,912
Selling, general and administrative
Stock-based Compensation [Line Items]
Stock-based compensation expense	5,646	2,088
Research and development
Stock-based Compensation [Line Items]
Stock-based compensation expense	$ 1,970	$ 824

Equity Incentive Plans - Total

Equity Incentive Plans - Total Unrecognized Stock-Based Compensation Expense, Net of Estimated Forfeitures (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($)
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Expense	$ 522
Average Remaining Vesting Period (Years)	4 months 24 days
Stock option grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Expense	$ 59,367
Average Remaining Vesting Period (Years)	3 years 1 month 6 days
RSU grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Expense	$ 49,955
Average Remaining Vesting Period (Years)	3 years 3 months 18 days

Equity Incentive Plans - Stock

Equity Incentive Plans - Stock Options Activity (Details)	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Number of Shares
Options outstanding balance, beginning (in shares) | shares	22,168,000
Options granted (in shares) | shares	6,502,000
Options exercised (in shares) | shares	(702,000)
Options forfeited or canceled (in shares) | shares	(178,000)
Options outstanding balance, ending (in shares) | shares	27,790,000
Options exercisable (in shares) | shares	12,856,000
Weighted-Average Exercise Price per Share
Options outstanding balance, beginning (in dollars per share) | $ / shares	$ 4.20
Options granted (in dollars per share) | $ / shares	8.68
Options exercised (in dollars per share) | $ / shares	3.11
Options forfeited or canceled (in dollars per share) | $ / shares	2.83
Options outstanding balance, ending (in dollars per share) | $ / shares	5.29
Options exercisable (in dollars per share) | $ / shares	$ 5.29

Equity Incentive Plans - Restri

Equity Incentive Plans - Restricted Stock Units Activity (Details) - Restricted stock units shares in Thousands	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Number of RSUs
Outstanding balance, beginning (in shares) | shares	3,646
Granted (in shares) | shares	4,901
Vested (in shares) | shares	(552)
Forfeited (in shares) | shares	(60)
Outstanding balance, ending (in shares) | shares	7,935
Weighted-Average Grant Date Fair Value Per Share
Outstanding balance, beginning (in dollars per share) | $ / shares	$ 3.09
Granted (in dollars per share) | $ / shares	8.68
Vested (in dollars per share) | $ / shares	5.62
Forfeited (in dollars per share) | $ / shares	2.64
Outstanding balance, ending (in dollars per share) | $ / shares	$ 6.37

Equity Incentive Plans - Narrat

Equity Incentive Plans - Narrative (Details) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($) $ / shares shares
Board of directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock for services (in shares)	0
ESPP shares issuable
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock under employee stock purchase plan (in shares)	0.3
Purchase price (in dollars per share) | $ / shares	$ 4.10
Proceeds from ESPP | $	$ 1

Net Loss Per Share - Computatio

Net Loss Per Share - Computation of Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Numerator:
Net loss	$ (26,518)	$ (26,773)
Denominator:
Weighted average common shares outstanding - basic (in shares)	233,065,960	207,023,127
Weighted average common shares outstanding - diluted (in shares)	233,065,960	207,023,127
Net loss per share of common stock - basic (in dollars per share)	$ (0.11)	$ (0.13)
Net loss per share of common stock - diluted (in dollars per share)	$ (0.11)	$ (0.13)

Net Loss Per Share - Anti Dilut

Net Loss Per Share - Anti Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	33,932	22,991
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	26,681	19,855
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	7,024	2,931
ESPP shares issuable
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	227	205

Net Loss Per Share - Narrative

Net Loss Per Share - Narrative (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Earnings Per Share [Abstract]
Anti-dilutive securities not included in computation of diluted net loss per share	33,932	22,991

Contingencies (Details)

Contingencies (Details)			4 Months Ended
	Jul. 19, 2022 claim	Aug. 12, 2021 defendant claim	Mar. 29, 2022 defendant claim	Mar. 31, 2024 USD ($)
Contingencies [Line Items]
Contingent liabilities | $				$ 0
Strezsak v. Ardelyx, Inc.
Contingencies [Line Items]
Number of lawsuits | claim	2	2
Number of defendants | defendant		2
Go v. Raab
Contingencies [Line Items]
Number of lawsuits | claim			2
Number of defendants | defendant			2