Ardelyx (ARDX) 10-Q 3 Nov 22 2022 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Sep. 30, 2022	Oct. 31, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2022
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		187,459,645
Entity Central Index Key	0001437402
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONDENSED BALANCE SHEETS

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 61,628	$ 72,428
Short-term investments	28,995	44,261
Accounts receivable	5,208	502
Inventory	1,250	0
Prepaid commercial manufacturing	16,145	9,406
Prepaid expenses and other current assets	6,649	7,052
Total current assets	119,875	133,649
Right-of-use assets	10,182	12,752
Property and equipment, net	1,294	2,362
Other assets	13,321	1,150
Total assets	144,672	149,913
Current liabilities:
Accounts payable	3,113	4,277
Accrued compensation and benefits	7,165	5,422
Current portion of long-term debt	26,541	32,264
Current portion of operating lease liability	3,791	3,492
Deferred revenue	4,003	0
Accrued expenses and other current liabilities	7,338	7,366
Total current liabilities	51,951	52,821
Operating lease liability, net of current portion	6,878	9,748
Deferred revenue, non-current	8,560	4,727
Deferred royalty obligation related to the sale of future royalties	10,422	0
Total liabilities	77,811	67,296
Commitments and contingencies (Note 15)
Stockholders’ equity:
Preferred stock, $0.0001 par value; 5,000,000 shares authorized; no shares issued and outstanding as of September 30, 2022 and December 31, 2021, respectively.	0	0
Common stock, $0.0001 par value; 300,000,000 shares authorized; 187,399,645 and 130,182,535 shares issued and outstanding as of September 30, 2022 and December 31, 2021, respectively.	19	13
Additional paid-in capital	857,788	795,540
Accumulated deficit	(790,832)	(712,930)
Accumulated other comprehensive loss	(114)	(6)
Total stockholders’ equity	66,861	82,617
Total liabilities and stockholders’ equity	$ 144,672	$ 149,913

CONDENSED BALANCE SHEETS (Paren

CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2022	Dec. 31, 2021
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)	300,000,000	300,000,000
Common stock, shares issued (in shares)	187,399,645	130,182,535
Common stock, shares outstanding (in shares)	187,399,645	130,182,535

CONDENSED STATEMENTS OF OPERATI

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenues:
Total revenues	$ 4,986,000	$ 1,173,000	$ 7,980,000	$ 9,068,000
Operating expenses:
Cost of revenue	732,000	0	955,000	1,000,000
Research and development	7,467,000	23,695,000	26,059,000	70,172,000
Selling, general and administrative	18,667,000	19,714,000	56,868,000	56,969,000
Total operating expenses	26,866,000	43,409,000	83,882,000	128,141,000
Loss from operations	(21,880,000)	(42,236,000)	(75,902,000)	(119,073,000)
Interest expense	(886,000)	(1,216,000)	(2,409,000)	(3,518,000)
Non-cash interest expense related to the sale of future royalties	(831,000)	0	(841,000)	0
Other income (expense), net	704,000	(134,000)	1,258,000	664,000
Loss before provision for income taxes	(22,893,000)	(43,586,000)	(77,894,000)	(121,927,000)
Provision for income taxes	0	1,000	8,000	4,000
Net loss	$ (22,893,000)	$ (43,587,000)	$ (77,902,000)	$ (121,931,000)
Net loss per common share - basic (in dollars per share)	$ (0.14)	$ (0.42)	$ (0.53)	$ (1.21)
Net loss per common share - diluted (in dollars per share)	$ (0.14)	$ (0.42)	$ (0.53)	$ (1.21)
Shares used in computing net loss per share - basic (in shares)	165,104,789	104,144,606	147,319,818	100,480,156
Shares used in computing net loss per share - diluted (in shares)	165,104,789	104,144,606	147,319,818	100,480,156
Comprehensive loss:
Net loss	$ (22,893,000)	$ (43,587,000)	$ (77,902,000)	$ (121,931,000)
Unrealized (losses) gains on available-for-sale securities	(5,000)	(1,000)	(108,000)	7,000
Comprehensive loss	(22,898,000)	(43,588,000)	(78,010,000)	(121,924,000)
Product sales, net
Revenues:
Total revenues	4,885,000	0	6,899,000	0
Product supply revenue
Revenues:
Total revenues	92,000	285,000	1,058,000	411,000
Licensing revenue
Revenues:
Total revenues	9,000	2,000	23,000	5,007,000
Collaborative development revenue
Revenues:
Total revenues	$ 0	$ 886,000	$ 0	$ 3,650,000

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, 2020		93,599,975
Beginning balance at Dec. 31, 2020	$ 126,112	$ 9	$ 680,872	$ (554,765)	$ (4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock purchase plan (in shares)		386,664
Issuance of common stock under employee stock purchase plan	819		819
Issuance of common stock for services (in shares)		25,989
Issuance of common stock for services	190		190
Issuance of common stock upon exercise of options (in shares)		331,310
Issuance of common stock upon exercise of options	584		584
Issuance of common stock upon vesting of restricted stock units (in shares)		114,194
Taxes paid for net share settlement of equity awards	(106)		(106)
Issuance of common stock in at the market offering (in shares)		12,313,452
Issuance of common stock in at the market offering	67,189	$ 2	67,187
Stock-based compensation	8,568		8,568
Unrealized (losses) gains on available-for-sale securities	7				7
Net loss	(121,931)			(121,931)
Ending balance (in shares) at Sep. 30, 2021		106,771,584
Ending balance at Sep. 30, 2021	81,432	$ 11	758,114	(676,696)	3
Beginning balance (in shares) at Dec. 31, 2020		93,599,975
Beginning balance at Dec. 31, 2020	126,112	$ 9	680,872	(554,765)	(4)
Ending balance (in shares) at Dec. 31, 2021		130,182,535
Ending balance at Dec. 31, 2021	82,617	$ 13	795,540	(712,930)	(6)
Beginning balance (in shares) at Jun. 30, 2021		102,967,017
Beginning balance at Jun. 30, 2021	117,569	$ 10	750,664	(633,109)	4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock purchase plan (in shares)		284,456
Issuance of common stock under employee stock purchase plan	341		341
Issuance of common stock for services (in shares)		25,989
Issuance of common stock for services	190		190
Issuance of common stock upon exercise of options (in shares)		126,004
Issuance of common stock upon exercise of options	21		21
Issuance of common stock upon vesting of restricted stock units (in shares)		34,410
Taxes paid for net share settlement of equity awards	(106)		(106)
Issuance of common stock in at the market offering (in shares)		3,333,708
Issuance of common stock in at the market offering	4,743	$ 1	4,742
Stock-based compensation	2,262		2,262
Unrealized (losses) gains on available-for-sale securities	(1)				(1)
Net loss	(43,587)			(43,587)
Ending balance (in shares) at Sep. 30, 2021		106,771,584
Ending balance at Sep. 30, 2021	81,432	$ 11	758,114	(676,696)	3
Beginning balance (in shares) at Dec. 31, 2021		130,182,535
Beginning balance at Dec. 31, 2021	82,617	$ 13	795,540	(712,930)	(6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock purchase plan (in shares)		308,356
Issuance of common stock under employee stock purchase plan	195		195
Issuance of common stock for services (in shares)		711,675
Issuance of common stock for services	$ 390		390
Issuance of common stock upon exercise of options (in shares)	0
Issuance of common stock upon vesting of restricted stock units (in shares)		3,091,697
Issuance of common stock in at the market offering (in shares)		53,105,382
Issuance of common stock in at the market offering	$ 52,845	$ 6	52,839
Stock-based compensation	8,824		8,824
Unrealized (losses) gains on available-for-sale securities	(108)				(108)
Net loss	(77,902)			(77,902)
Ending balance (in shares) at Sep. 30, 2022		187,399,645
Ending balance at Sep. 30, 2022	66,861	$ 19	857,788	(790,832)	(114)
Beginning balance (in shares) at Jun. 30, 2022		153,797,834
Beginning balance at Jun. 30, 2022	53,042	$ 15	821,075	(767,939)	(109)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock purchase plan (in shares)		181,256
Issuance of common stock under employee stock purchase plan	112		112
Issuance of common stock for services (in shares)		711,675
Issuance of common stock for services	390		390
Issuance of common stock upon vesting of restricted stock units (in shares)		95,555
Issuance of common stock in at the market offering (in shares)		32,613,325
Issuance of common stock in at the market offering	34,367	$ 4	34,363
Stock-based compensation	1,848		1,848
Unrealized (losses) gains on available-for-sale securities	(5)				(5)
Net loss	(22,893)			(22,893)
Ending balance (in shares) at Sep. 30, 2022		187,399,645
Ending balance at Sep. 30, 2022	$ 66,861	$ 19	$ 857,788	$ (790,832)	$ (114)

CONDENSED STATEMENTS OF CASH FL

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Operating activities
Net loss	$ (22,893)	$ (43,587)	$ (77,902)	$ (121,931)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense			1,035	2,312
Non-cash lease expense			2,570	2,257
Stock-based compensation			8,824	8,568
Change in derivative liabilities			54	(696)
Debt refinancing costs			102	0
Gain on sale of equipment			(1,260)	0
Non-cash interest expense			1,055	212
Changes in operating assets and liabilities:
Accounts receivable			(4,706)	(287)
Inventory			(9,774)	0
Prepaid commercial manufacturing			(10,549)	(4,954)
Prepaid expenses and other assets			754	1,027
Accounts payable			(1,164)	(1,363)
Accrued compensation and benefits			1,743	(902)
Operating lease liabilities			(2,571)	(2,033)
Accrued and other liabilities			(375)	5,411
Deferred revenue			7,836	(703)
Net cash used in operating activities			(84,328)	(113,082)
Investing activities
Proceeds from maturities and redemptions of investments			59,000	103,550
Purchases of investments			(43,824)	(72,736)
Proceeds from sale of property and equipment			1,798	0
Purchases of property and equipment			0	(1,962)
Net cash provided by investing activities			16,974	28,852
Financing activities
Proceeds from 2022 Loan, net of issuance costs			26,971	0
Repayment of 2018 Loan, net of settlement costs			(33,038)	0
Proceeds from the sale of future royalties, net of issuance costs			9,581	0
Proceeds from issuance of common stock in at the market offering, net of issuance costs			52,845	67,189
Proceeds from issuance of common stock under equity incentive and stock purchase plans			195	1,403
Payments for taxes related to net share settlement of equity awards			0	(106)
Net cash provided by financing activities			56,554	68,486
Net decrease in cash and cash equivalents			(10,800)	(15,744)
Cash and cash equivalents at beginning of period			72,428	91,032	$ 91,032
Cash and cash equivalents at end of period	$ 61,628	$ 75,288	61,628	75,288	$ 72,428
Supplementary disclosure of cash flow information:
Cash paid for interest			2,079	2,920
Cash paid for income taxes			6	4
Supplementary disclosure of non-cash activities:
Right-of-use assets obtained in exchange for lease obligations			0	14,379
Issuance of common stock for services			390	190
Issuance of derivative in connection with issuance of loan payable			$ 375	$ 0

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	ORGANIZATION AND BASIS OF PRESENTATION Ardelyx, Inc. (the “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 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, 2021. The results for the three and nine months ended September 30, 2022 are not necessarily indicative of results to be expected for the entire year ending December 31, 2022, 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, the 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 September 30, 2022, we had cash and investments of approximately $90.6 million. We have incurred operating losses since inception and our accumulated deficit as of September 30, 2022 is $790.8 million. Our current level of cash and investments alone is not sufficient to meet our plans for the next twelve months following the issuance of these financial statements. These factors raise substantial doubt regarding our ability to continue as a going concern for a period of one year from the issuance of these financial statements. We plan to address our operating cash flow requirements with our current cash and investments, cash generated from sales of IBSRELA, our potential receipt of anticipated milestones from our collaboration partners, our potential receipt of anticipated payments from our Japanese collaboration partner under the second amendment to our License Agreement, our ability to access the capital markets, as well as through the implementation of cash preservation activities to reduce or defer discretionary spending. There are no assurances that our efforts to meet our operating cash flow requirements will be successful. If our current cash and investments as well as our plans to meet our operating cash flow requirements are not sufficient to fund necessary expenditures and meet our obligations for at least the next twelve months following the issuance of these financial statements, our liquidity, financial condition and business prospects will be materially affected. These financial statements have been prepared on a going concern basis and do not include any adjustments to the amounts and classification of assets and liabilities that may be necessary in the event that we can no longer continue as a going concern. Summary of Significant Accounting Policies Our significant accounting policies are described in Note 1 to our audited financial statements for the fiscal year ended December 31, 2021, included in our Annual Report on Form 10-K. Our significant accounting policies for the three and nine months ended September 30, 2022 also included the policies discussed below related to accounts receivable, inventory, revenue and cost of revenue for commercial product sales. With the exception of those noted below, 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, 2021. Accounts Receivable Accounts receivable is reported net of allowances for returns, chargebacks and contractual off-invoice and prompt-pay discounts offered to our customers. Our estimate of the allowance for doubtful accounts is based on an evaluation of the aging of our receivables. Trade receivable balances are written off against the allowance when it is probable that the receivable will not be collected. To date, we have determined that an allowance for doubtful accounts is not required. As of September 30, 2022 our accounts receivable balance is comprised of $0.5 million from our collaboration agreements and $4.7 million from commercial customers. As of December 31, 2021 our accounts receivable balance was comprised of $0.5 million from our collaborators. Inventory We capitalize inventory costs associated with the production of our products after regulatory approval or when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Otherwise, such costs are expensed as research and development. Prior to the regulatory approval of drug product candidates, we incurred expenses for the manufacture of drug product that could potentially be available to support the commercial launch of our products or could be sold to our international partners under product supply agreements. We began to capitalize inventory costs associated with IBSRELA during the fourth quarter of 2021, when our intent to commercialize IBSRELA was established and we commenced preparation for the commercial launch of IBSRELA, which was when it was determined that the inventory had a probable future economic benefit. Inventory is stated at the lower of cost or estimated net realizable value with cost determined under the first-in first-out method. Inventory costs include the cost of materials, third-party contract manufacturing, third-party packaging services, freight, labor costs for personnel involved in the manufacturing process, and indirect overhead costs. We primarily use actual costs to determine the cost basis for inventory. The determination of whether inventory costs will be realizable requires management review of the expiration dates of IBSRELA compared to our forecasted sales. If actual market conditions are less favorable than projected by management, write-downs of inventory may be required, which would be recorded as cost of revenue in the condensed statement of operations and comprehensive loss. A portion of inventory is included in other assets on our condensed balance sheets as a non-current asset. The non-current balance represents product that is not expected to be sold or used within the next 12 months. Product Sales, Net We account for our commercial product sales, net in accordance with Topic 606 - Revenue from Contracts with Customers . We received approval from the U.S. Food and Drug Administration (“FDA”) in September 2019 to market IBSRELA, the first and only sodium hydrogen exchanger 3 (“NHE3”) inhibitor for the treatment of irritable bowel syndrome with constipation ("IBS-C") in adults, in the United States ("U.S."). We began selling IBSRELA in the U.S. in March 2022. We distribute IBSRELA principally through major wholesalers, specialty pharmacies and group purchasing organizations ("GPOs") (collectively, our "Customers"). Our Customers subsequently sell IBSRELA to pharmacies and patients. Separately, we enter into arrangements with third parties that provide for government-mandated rebates, chargebacks and discounts. Revenue from product sales is recognized when our performance obligations are satisfied, which is when Customers obtain control of our product and occurs upon delivery. Reserves for Variable Consideration Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration, including discounts which may be settled in the form of off-invoice discounts, chargebacks, or rebates depending on the customer, wholesaler fees, group purchasing organization administrative fees, patient copay assistance programs, and estimated product returns. These estimates are based on the amounts earned or to be claimed for related sales and are classified as reductions of gross accounts receivable if settlement is expected to occur through a reduction in the amounts paid by our customers or a current liability if settlement is expected to occur through a payment from us. Where appropriate, these estimates are based on factors such as industry data and forecasted customer buying and payment patterns, our historical experience, current contractual and statutory requirements, specific known market events and trends. Overall, these reductions to gross sales reflect our best estimates of the amount of consideration to which we are entitled based on the terms of the contract. Variable consideration is included in the transaction price only to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Actual amounts of consideration ultimately received may differ from our estimates. If actual results in the future vary from our estimates, we adjust these estimates, which would affect product revenue and earnings in the period such variances become known. As we gain more historical experience, estimates will be more heavily based on the expected utilization from historical data we have accumulated since the IBSRELA product launch. Rebates: Rebates include wholesaler fees, GPO fees, as well as mandated discounts under the Medicaid Drug Rebate Program ("Medicaid") and the Medicare Coverage Gap Program ("Medicare"). Estimates for rebates are recorded in the same period the related gross revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability which is included in accrued expenses on the condensed balance sheets. We estimate our Medicaid and Medicare rebates based upon the estimated payor mix, and statutory discount rates. Our estimates for payor mix are guided by payor information received from specialty pharmacies, expected utilization for wholesaler sales to pharmacies, and available industry payor information. Chargebacks: Chargebacks are discounts that occur when certain contracted purchasers purchase directly from our wholesalers at a discounted price. The wholesaler, in turn, charges back the difference between the price initially paid to us by the wholesaler and the discounted price paid to the wholesaler by the contracted purchaser. Amounts for estimated chargebacks are established in the same period that the related gross revenue is recognized, resulting in a reduction of product revenue and accounts receivable. The accrual for wholesaler chargebacks is estimated based on known chargeback rates, known sales to wholesalers, and estimated utilization by types of contracted purchasers. Discounts and Fees: Our payment terms are generally 30 to 60 days. Wholesalers, GPOs and specialty pharmacies are offered various forms of consideration, including off-invoice discounts which may be paid to GPOs and specialty pharmacies. Wholesalers and GPOs may also receive prompt pay discounts for payment within a specified period. We expect discounts to be earned when offered and therefore, we deduct the full amount of these discounts from product sales when revenue is recognized, resulting in a reduction of product revenue and accounts receivable. Other Reserves: Patients who have commercial insurance may receive copay assistance when product is dispensed by pharmacies to patients. We estimate the amount of copay assistance provided to eligible patients based on the terms of the program and redemption information provided by third-party claims processing organizations and are recorded in accounts payable and accrued expenses and other current liabilities on the condensed balance sheets. Other reserves include estimated product returns which are recorded in the same period the related gross revenue is recognized, resulting in a reduction of product revenue as well as gross accounts receivable. We estimate our product returns reserve based upon our historical experience, and specific known market events and trends Cost of Revenue Cost of revenue consists of the cost of commercial goods sold to our Customers and international partners under product supply agreements, as well as royalty expense based on sales of tenapanor. We capitalize inventory costs associated with the production of our products after regulatory approval or when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Otherwise, such costs are expensed as research and development. A portion of the costs of IBSRELA units recognized as revenue during the three and nine months ended September 30, 2022 were expensed prior to the fourth quarter of 2021, at which time our intent to commercialize IBSRELA was established and we commenced preparation for the commercial launch of IBSRELA. Cost of revenue includes payments due to AstraZeneca, which under the terms of a termination agreement entered into in 2015 (the "AZ Termination Agreement") is entitled to (i) future royalties at a 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 our collaboration partners as a result of the development and commercialization of tenapanor or certain other NHE3 inhibitors. We have agreed to pay AstraZeneca up to a maximum of $75.0 million in the aggregate for (i) and (ii). We recognize these expenses as cost of revenue when we recognize the corresponding revenue that gives rise to payments due to AstraZeneca. To date, we have recognized an aggregate of $12.4 million as cost of revenue under the AZ Termination Agreement. Non-cash Interest Expense on Deferred Royalty Obligation The net proceeds we receive from the sale of certain future royalties are recorded as deferred royalty obligation related to the sale of future royalties on our balance sheets. As we earn royalties and remit those royalties pursuant to the agreement, the balance of the deferred royalty obligation will be effectively repaid over the life of agreement and non-cash interest expense related to the sale of future royalties is recorded using the effective interest method. To determine the amortization of our deferred royalty obligation, we are required to estimate the total amount of future royalty payments we expect to earn. There are a number of factors that could materially affect the amount and timing of royalty payments, most of which are not within our control. We periodically assess the amount of royalty payments we expect to receive which are subject to the agreement 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. Recent Accounting Pronouncements New Accounting Pronouncements - Recently Adopted We have adopted no new accounting pronouncements other than those disclosed in our most recent Annual Report on Form 10-K. Recent Accounting Pronouncements Not Yet Adopted There were various accounting standards and interpretations issued recently, none of which are expected to a have a material impact on our financial position, operations or cash flows.

Cash, Cash Equivalents and Inve

Cash, Cash Equivalents and Investments	9 Months Ended
	Sep. 30, 2022
Cash and Cash Equivalents [Abstract]
Cash, Cash Equivalents and Investments	CASH, CASH EQUIVALENTS AND INVESTMENTS Securities classified as cash, cash equivalents and investments as of September 30, 2022 and December 31, 2021 are summarized below (in thousands): September 30, 2022 Gross Unrealized Amortized Cost Gains Losses Fair Value Cash and cash equivalents: Cash $ 652 $ — $ — $ 652 Money market funds 60,976 — — 60,976 Total cash and cash equivalents 61,628 — — 61,628 Short-term investments: Commercial paper $ 20,616 $ — $ (78) $ 20,538 U.S. government-sponsored agency bonds 1,480 — (1) 1,479 Corporate bonds 1,005 — (9) 996 U.S. treasury notes 6,008 — (26) 5,982 Total short-term investments 29,109 — (114) 28,995 Total cash equivalents and investments $ 90,737 $ — $ (114) $ 90,623 December 31, 2021 Gross Unrealized Amortized Cost Gains Losses Fair Value Cash and cash equivalents: Cash $ 1,253 $ — $ — $ 1,253 Money market funds 71,175 — — 71,175 Total cash and cash equivalents 72,428 — — 72,428 Short-term investments Commercial paper $ 31,936 $ 1 $ (2) $ 31,935 Corporate bonds 7,025 — (3) 7,022 Asset backed securities 5,306 — (2) 5,304 Total short-term investments 44,267 1 (7) 44,261 Total cash equivalents and investments $ 116,695 $ 1 $ (7) $ 116,689 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 income (loss) within stockholders’ equity on our condensed 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 been insignificant and are included in other income (expense), net, in the statement of operations and comprehensive loss. All short-term available-for-sale securities held as of September 30, 2022 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, 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. We did not identify any of our available-for-sale securities as other-than-temporarily impaired in any of the periods presented. As of September 30, 2022, no investment was in a continuous unrealized loss position for more than one year and 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	9 Months Ended
	Sep. 30, 2022
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): September 30, 2022 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 60,976 $ 60,976 $ — $ — Commercial paper 20,538 — 20,538 — U.S. government-sponsored agency bonds 1,479 — 1,479 — Corporate bonds 996 — 996 — U.S. treasury notes 5,982 — 5,982 — Total $ 89,971 $ 60,976 $ 28,995 $ — Liabilities: Derivative liabilities for exit fees $ 1,127 $ — $ — $ 1,127 Total $ 1,127 $ — $ — $ 1,127 December 31, 2021 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 71,175 $ 71,175 $ — $ — Commercial paper 31,935 — 31,935 — Corporate bonds 7,022 — 7,022 — Asset-backed securities 5,304 — 5,304 — Total $ 115,436 $ 71,175 $ 44,261 $ — Liabilities: Derivative liability for exit fee $ 698 $ — $ — $ 698 Total $ 698 $ — $ — $ 698 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 notes, 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 2018 Exit Fee and 2022 Exit Fee, as defined and discussed in Note 9. Derivative Liability , are classified as Level 3. The carrying amounts reflected in the condensed balance sheets for cash equivalents, short-term investments, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values at both September 30, 2022 and December 31, 2021, due to their short-term nature. 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 September 30, 2022 and December 31, 2021. 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 September 30, 2022 and is based on our current estimates of future royalties and commercialization milestones expected to be paid to us by KKC 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	9 Months Ended
	Sep. 30, 2022
Inventory Disclosure [Abstract]
Inventory	INVENTORY We began capitalizing inventory during the fourth quarter of 2021, at which time our intent to commercialize IBSRELA was established and we commenced preparation for the commercial launch of IBSRELA. Inventory consisted of the following (in thousands): September 30, 2022 Raw materials $ 5,798 Work in process 2,907 Finished goods 1,069 Total $ 9,774 Reported as: Inventory $ 1,250 Other assets 8,524 Total $ 9,774 Prepaid commercial manufacturing of $16.1 million and $9.4 million as of September 30, 2022 and December 31, 2021, respectively, consist of prepayments to third party contract manufacturing organizations for the manufacture of IBSRELA for production orders which we expect work to commence within the next 12 months. Prepayments for commercial manufacturing of $3.8 million as of September 30, 2022 that are expected to be converted into inventory after 12 months are included in other assets on our condensed balance sheets.

Product Revenue, Net

Product Revenue, Net	9 Months Ended
	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Product Revenue, Net	PRODUCT REVENUE, NET We received approval from the FDA in September 2019 to market IBSRELA, the first and only NHE3 inhibitor for the treatment of IBS-C in adults, in the U.S. We began selling IBSRELA in the U.S. in March 2022. We recorded net revenue for IBSRELA of $4.9 million and $6.9 million during the three and nine months ended September 30, 2022, respectively. Sales to AmerisourceBergen Drug Corporation, Cardinal Health, and McKesson Corporation made up 26.4%, 25.2%, and 20.2% of our gross product revenue during the three months ended September 30, 2022 and 28.9%, 24.2%, and 20.9% during the nine months ended September 30, 2022. 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 Other Fees, Copay and Returns Total Balance as of December 31, 2021 $ — $ — $ — $ — Activity related to 2022 sales 358 1,158 1,115 2,631 Credits/deductions issued (250) (438) (576) (1,264) Balance as of September 30, 2022 $ 108 $ 720 $ 539 $ 1,367 There were no product sales or gross-to-net accruals during the three and nine months ended September 30, 2021.

Collaboration and Licensing Agr

Collaboration and Licensing Agreements	9 Months Ended
	Sep. 30, 2022
Collaboration and Licensing Agreements
Collaboration and Licensing Agreements	COLLABORATION AND LICENSING AGREEMENTS Kyowa Kirin Co., Ltd. (“KKC”) 2019 KKC Agreement In November 2019, we entered into a research collaboration and option agreement with KKC (the “2019 KKC Agreement”) for research associated with identifying two preclinical compounds that are ready for designation as development compounds (“DCs”). Pursuant to the 2019 KKC Agreement, upon completion of the research and designation by the research steering committee of one or more DCs, KKC has the right to execute one or more separate collaborative agreements relating to the development and commercialization of one or both DCs in certain specified territories. Under the terms of the 2019 KKC Agreement, KKC paid us a non-refundable, non-creditable upfront fee of $10.0 million in two installments as follows: the first installment of $5.0 million within 30 days of November 11, 2019 (the “Effective Date”), and the second installment of $5.0 million on the first anniversary of the Effective Date. The original term of the 2019 KKC Agreement commenced on the Effective Date and was to end on the earliest of: (i) 2 years following the Effective Date, (ii) the nomination of a program DC for both programs, (iii) the nomination of one program DC and the decision by the parties to cease research for the other program, or (iv) the decision by the parties to cease research for both programs. We entered into three amendments to the 2019 KKC Agreement, which have resulted in the extension of the original term. Under the third amendment to the 2019 KKC Agreement entered into on June 28, 2022, the current term will end on February 28, 2023. We have no material future obligations under the 2019 KKC Agreement and recorded no revenue under the 2019 KKC Agreement during the three and nine months ended September 30, 2022. During the three and nine months ended September 30, 2021, we recognized $0.9 million and $3.7 million, respectively, as collaborative development revenue under the 2019 KKC Agreement in the accompanying condensed statement of operations and comprehensive loss. 2017 KKC Agreement In November 2017, we entered into an exclusive license agreement with KKC (the “2017 KKC Agreement”), under which we granted KKC 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 KKC Agreement, KKC 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 KKC’s use in development and commercialization throughout the term of the 2017 KKC Agreement, provided that KKC may exercise an option to manufacture the tenapanor drug substance under certain conditions. 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, KKC, is a customer. Under the terms of the 2017 KKC 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 KKC Agreement, and as such, each of the performance obligations is distinct. Under the terms of the 2017 KKC Agreement, KKC paid us an up-front license fee of $30.0 million. We may be entitled to receive up to $55.0 million in total development and regulatory milestones, of which $10.0 million has been received and recognized as revenue as of September 30, 2022. We may also be eligible to receive approximately ¥8.5 billion for commercialization milestones, or approximately $58.7 million at the currency exchange rate on September 30, 2022, 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 , the future royalties and commercial milestone payments we may receive under the 2017 KKC 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 has not been included in the transaction price as these were fully constrained at September 30, 2022. Please see Note 16 Subsequent Events related to the October 31, 2022 KKC submission of a NDA to the Japanese Ministry of Health, Labour and Welfare for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis. On April 11, 2022, we entered into a second amendment to the 2017 KKC Agreement (the "2022 Amendment"). Under the terms of the 2022 Amendment, we and KKC have agreed to a reduction in the royalty rate payable to us by KKC upon net sales of tenapanor 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 , the future commercial milestones and royalties we may receive under the 2017 KKC Agreement will be remitted to HealthCare Royalty Partners IV, L.P. pursuant to a Royalty and Sales Milestone Interest Acquisition Agreement. As consideration for the reduction in the royalty rate, KKC has agreed to pay us up to an additional $40.0 million payable in two tranches, with the first payment due following KKC's filing with the Japanese Ministry of Health, Labour and Welfare of its application for marketing approval for tenapanor and the second payment due following KKC’s receipt of regulatory approval to market tenapanor for hyperphosphatemia in Japan. The variable consideration related to the reduction in the royalty rate has not been included in the transaction price as these were fully constrained at September 30, 2022. During the three and nine months ended September 30, 2022 we recognized no licensing revenue related to the 2017 KKC Agreement. During the three and nine months ended September 30, 2021, we recognized zero and $5.0 million respectively, as licensing revenue upon the initiation of phase 3 clinical studies by KKC in Japan to evaluate tenapanor for hyperphosphatemia. During the three and nine months ended September 30, 2022, we recognized $83 thousand and $1.0 million, respectively, as product supply revenue related to the manufacturing supply of tenapanor and other materials to KKC pursuant to the 2017 KKC Agreement. During the three and nine months ended September 30, 2021, we recognized $0.3 million and $0.4 million, respectively, as product supply revenue pursuant to the 2017 KKC Agreement. As detailed below under the heading Deferred revenue - non-current , we have received prepayments from KKC for the manufacturing of tenapanor drug substance that will be used to satisfy KKC needs. Shanghai Fosun Pharmaceutical Industrial Development Co. Ltd. (“Fosun Pharma”) In December 2017, we entered into an exclusive license agreement with Fosun Pharma (the “Fosun Agreement”), for the development, commercialization and distribution of tenapanor in China for both hyperphosphatemia and IBS-C. Under the terms of the Fosun Agreement, Fosun paid us a $12.0 million upfront license fee. We may be entitled to receive development and commercialization milestones of up to $113.0 million, of which $3.0 million has been received and recognized as revenue as of September 30, 2022, 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 has not been included in the transaction price as these were fully constrained at September 30, 2022. During the three and nine months ended September 30, 2022, we recognized $9 thousand as product supply revenue pursuant to the terms of the Fosun Agreement. We recorded no revenue during the three and nine months ended September 30, 2021 related to the Fosun Agreement. Knight Therapeutics, Inc. (“Knight“) In March 2018, we entered into an exclusive license agreement with Knight (the “Knight Agreement”) for the development, commercialization and distribution of tenapanor in Canada for hyperphosphatemia and IBS-C. Under the terms of the Knight Agreement, Knight paid us a $2.3 million upfront payment. We may also be eligible to receive approximately CAD22.2 million for development and commercialization milestones, or approximately $16.1 million at the currency exchange rate on September 30, 2022, of which $0.7 million has been received and recognized as revenue as of September 30, 2022. We are also eligible to receive royalties throughout the term of the agreement, and a transfer price for manufacturing services. The variable consideration related to the remaining development milestone payments has not been included in the transaction price as they were fully constrained at September 30, 2022. During the three and nine months ended September 30, 2022, we recognized $9 thousand and $23 thousand, respectively, as licensing revenue under the terms of the Knight Agreement. During the three and nine months ended September 30, 2021, we recognized $2 thousand and $7 thousand respectively, under the terms of the Knight Agreement. AstraZeneca AB (“AstraZeneca”) In June 2015, we entered into a termination agreement with AstraZeneca (the “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 licensee of tenapanor or another NHE3 inhibitor, up to a maximum of $75.0 million in aggregate for (i) and (ii). As of September 30, 2022, to date in aggregate, we have recognized $12.4 million of the $75.0 million, which has been recorded as cost of revenue, and have paid AstraZeneca $11.6 million. During the three and nine months ended September 30, 2022 we recognized and recorded as cost of revenue $0.5 million and $0.8 million, respectively, related to the AstraZeneca Termination Agreement. During the three and nine months ended September 30, 2021 we recognized zero and $1.0 million, respectively, as 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. The September 30, 2022 deferred revenue balance is attributable entirely to the 2017 KKC Agreement, while the current September 30, 2021 deferred revenue balance is attributable to the 2019 KKC Agreement and the non-current September 30, 2021 deferred revenue balance is attributable to the 2017 KKC Agreement (in thousands): Deferred revenue - current 2022 2021 Balance at January 1, $ — $ 4,177 Increases due to amounts reclassified from non-current, to be recognized in the next twelve months 3,961 Increases to amounts invoiced, for which cash has not yet been received 42 — Decreases due to revenue recognized in the period for which cash has been received — (3,650) Balance at September 30, $ 4,003 $ 527 Deferred revenue - non-current 2022 2021 Balance at January 1, $ 4,727 $ — Increases due to cash received during the period 7,694 2,947 Increases to amounts invoiced, for which cash has not yet been received 100 — Decreases due to amounts reclassified as current, to be recognized in the next twelve months (3,961) — Balance at September 30, $ 8,560 $ 2,947

Deferred Royalty Obligation Rel

Deferred Royalty Obligation Related To The Sale Of Future Royalties	9 Months Ended
	Sep. 30, 2022
Advance Royalties [Abstract]
Deferred Royalty Obligation Related To The Sale Of Future Royalties	DEFERRED ROYALTY OBLIGATION RELATED TO THE SALE OF FUTURE ROYALTIES On June 28, 2022, we and HealthCare Royalty Partners IV, L.P. (“HCR”) entered into a Royalty and Sales Milestone Interest Acquisition Agreement (the “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 KKC based upon KKC's net sales of tenapanor in Japan. As consideration for the sale of the Royalty Interest Payments, HCR paid to us a $10.0 million upfront payment, and we are eligible to receive a $5.0 million payment following KKC's receipt of regulatory approval to market tenapanor for hyperphosphatemia in Japan, and another $5.0 million payment in the event net sales by KKC 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 KKC Agreement, to create or incur any liens with respect to the Royalty Interest Payments, the 2017 KKC Agreement or certain patents, or to sell, license or transfer certain patents in the field and territory described in the 2017 KKC 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 KKC 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 KKC 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. We received the $10.0 million upfront payment from HCR during June 2022 and recorded it as a deferred royalty obligation related to the sale of future royalties (the "deferred royalty obligation") on our condensed balance sheet. Due to our ongoing manufacturing obligations under the 2017 KKC Agreement, we account for the proceeds as imputed debt and therefore will recognize royalties received 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 KKC. 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 KKC, 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 amount and timing of royalty payments from KKC, most of which are not within our control. We will periodically assess the estimated royalty payments from KKC and, to the extent that the amount or timing of such payments is materially different than our original estimates, we will prospectively adjust the imputed interest rate and the related amortization of the deferred royalty obligation. As of September 30, 2022, our effective interest rate used to amortize the liability is 34.4%. During the three and nine months ended September 30, 2022, we recognized approximately $0.8 million of non-cash interest expense for the amortization of the deferred royalty obligation. As of September 30, 2022, we have received no royalty payments from KKC and, therefore, the deferred royalty obligation has not begun to be reduced.

Borrowing

Borrowing	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Borrowing	BORROWING Solar Capital and Western Alliance Bank Loan Agreement On May 16, 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) (the "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 (the “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 Liability , 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 (the "2018 Exit Fee"). Our obligations for the 2018 Exit Fee remain outstanding following the full repayment of the 2018 Loan in February 2022. SLR Investment Corp. Loan Agreement On February 23, 2022 (the “Closing Date”), we entered into a loan and security agreement (the “2022 Loan Agreement”) with SLR Investment Corp. as collateral agent (the “Agent”), and the lenders listed in the 2022 Loan Agreement (collectively the “2022 Lenders”). The 2022 Loan Agreement provides for a senior secured loan facility, with $27.5 million (the “Term A Loan”) funded on the Closing Date and an additional $22.5 million that we may borrow on or prior to July 25, 2023; provided that (i) we have received approval by the FDA for our NDA for the control of serum phosphorus in chronic kidney disease patients on dialysis by December 31, 2022, and (ii) we have achieved certain product revenue milestone targets described in the 2022 Loan Agreement (the “Term B Loan”, and collectively, the Term A Loan and the Term B Loan, the “2022 Loan”). On August 1, 2022, we entered into an amendment to the 2022 Loan Agreement with SLR Investment Corp. that extends the date by which we must receive approval by the FDA for our NDA for the control of serum phosphorus in chronic kidney disease patients on dialysis in order to borrow the additional $22.5 million from December 31, 2022 to March 31, 2023. The 2022 Term A Loan funds were used to repay the 2018 Loan with the 2018 Lenders. The 2022 Loan has a maturity date of March 1, 2027. Borrowings under the 2022 Loan bear interest at a floating per annum rate equal to 7.95% plus the greater of (i) one tenth percent (0.10%) and (ii) the one-month rate published by the Intercontinental Exchange Benchmark Administration Ltd or its successor. We are permitted to make interest-only payments on the 2022 Loan through March 31, 2024. Accordingly, beginning on April 1, 2024, we will be required to make monthly payments of interest plus repay the 2022 Loan in consecutive equal monthly installments of principal over 36 months. We were obligated to pay $0.2 million, upon the closing of the Term A Loan, and we are obligated to pay $0.1 million on the earliest of (i) the funding date of the Term B Loan, (ii) July 25, 2023, and (iii) the prepayment, refinancing, substitution, or replacement of the Term A Loan on or prior to July 25, 2023. We are obligated to pay a final fee equal to 4.95% of the aggregate original principal amount of the 2022 Loan funded upon the earliest to occur of the maturity date, the acceleration of the 2022 Loan, and the prepayment, refinancing, substitution, or replacement of the 2022 Loan. We may voluntarily prepay the outstanding 2022 Loan balance, subject to a prepayment premium of (i) 3% of the outstanding principal amount of the 2022 Loan if prepaid prior to or on the first anniversary of the Closing Date, (ii) 2% of the outstanding principal amount of the 2022 Loan if prepaid after the first anniversary of the Closing Date through and including the second anniversary of the Closing Date, or (iii) 1% of the outstanding principal amount of the 2022 Loan if prepaid after the second anniversary of the Closing Date and prior to the maturity date. The 2022 Loan is secured by substantially all of our assets, except for our intellectual property and certain other customary exclusions. Additionally, in connection with the 2022 Loan, we entered into an agreement, whereby we agreed to pay an exit fee in the amount of 2% of the 2022 Loan funded (the “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, tested monthly at the end of each month. 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 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 and cash equivalents to be less than the eighty percent (80%) of the outstanding 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 2022 Loan balance. In addition, the 2022 Loan Agreement 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 2022 Term Loan, 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 Loan balance as a current liability as of September 30, 2022 due to the determination of the existence of substantial doubt about our ability to continue operating as a going concern discussed in Note 1. Organization and Basis of Presentation: Liquidity and our assessment that the material adverse change clause under the 2022 Loan Agreement is not within our control. The lenders have not invoked the material adverse change clause as of the date of issuance of these financial statements. As of September 30, 2022, our future payment obligations related to the 2022 Loan, excluding interest payments and the 2022 final fee, are as follows (in thousands): Total repayment obligations $ 28,862 Less: Unamortized discount (1,185) Less: Unaccreted value of final fee (1,136) Long-term debt 26,541 Less: Current portion of long-term debt (26,541) Long-term debt, net of current portion $ —

Derivative Liability

Derivative Liability	9 Months Ended
	Sep. 30, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Liability	DERIVATIVE LIABILITY 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 (the “2018 Exit Fee”) upon any change of control transaction in respect of the Company or if we obtain both (i) FDA approval of tenapanor for the control of serum phosphorus in adult patients with CKD on dialysis and (ii) FDA approval of tenapanor for the treatment of patients with IBS-C, which was obtained on September 12, 2019 when the FDA approved IBSRELA ® (tenapanor), a 50 milligram, twice daily oral pill for the treatment of IBS-C in adults (the “2018 Exit Fee Agreement”). Notwithstanding the February 2022 prepayment of the 2018 Loan our obligation to pay the 2018 Exit Fee will expire on May 16, 2028. We concluded that the 2018 Exit Fee is a freestanding derivative which should be accounted for at fair value on a recurring basis. The estimated fair value of the 2018 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 both September 30, 2022 and December 31, 2021, the estimated fair value of the 2018 Exit Fee was $0.7 million. 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 2018 derivative liability include: (i) our estimates of both the probability and timing of a potential $1.5 million payment to the 2018 Lenders as a result of the FDA approvals and (ii) a discount rate which was derived from our estimated cost of debt, adjusted with current LIBOR (or a comparable successor rate if LIBOR no longer exists). 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 10.0% increase (decrease), not to exceed 100%, in the probability of occurrence would result in a fair value fluctuation of no more than $0.1 million. 2022 Exit Fee On February 23, 2022, in connection with entering into the 2022 Loan Agreement, we entered into an agreement, whereby we agreed to pay an exit fee in the amount of 2% of the 2022 Loan funded (the “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 (the "Revenue Milestone"), tested monthly at the end of each month. 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 September 30, 2022, the estimated fair value of the 2022 Exit Fee is $0.4 million. 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 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 is dependent upon (a) approval by the FDA for our NDA for the control of serum phosphorus in chronic kidney disease patients on dialysis by December 31, 2022, and (b) achievement of certain product revenue milestone targets. 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 10.0% increase (decrease) in the probability of occurrence would not result in a material fair value fluctuation. Changes in the fair value of our exit fee derivative liabilities recurring measurements included in Level 3 of the fair value hierarchy are presented as other income, net in our statements of operations and were as follows for the three and nine months ended September 30, 2022 and 2021 (in thousands): 2022 2021 Balance at January 1, $ 698 $ 1,376 2022 Exit Fee addition at fair value 375 — Changes in estimated fair value: 2018 Exit Fee $ (4) $ (696) 2022 Exit Fee $ 58 $ — Balance at September 30, $ 1,127 $ 680

Leases

Leases	9 Months Ended
	Sep. 30, 2022
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 September 30, 2022 December 31, 2021 Right-of-use assets $ 10,182 $ 12,752 Current portion of lease liabilities 3,791 3,492 Operating lease liability, net of current portion 6,878 9,748 Total $ 10,669 $ 13,240 Weighted-average remaining life (years) 2.7 3.4 Weighted-average discount rate 6.8 % 6.9 % Lease costs, which are included in operating expenses in our statements of operations, were as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Operating lease expense $ 1,064 $ 1,096 $ 3,192 $ 2,606 Cash paid for operating lease $ 1,072 $ 829 $ 3,194 $ 2,383 The following table summarizes our undiscounted cash payment obligations for our operating lease liabilities as of September 30, 2022 (in thousands): Remainder of 2022 $ 1,097 2023 4,440 2024 4,589 2025 1,321 2026 253 Total undiscounted operating lease payments 11,700 Imputed interest expenses (1,031) Total operating lease liabilities 10,669 Less: Current portion of operating lease liability (3,791) Operating lease liability, net of current portion $ 6,878

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2022
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 ("Registration Statement"), containing (i) a base prospectus for the offering, issuance and sale by us of up to a maximum aggregate offering price of $250.0 million of our common stock, preferred stock, debt securities, warrants and/or units, from time to time in one or more offerings; and (ii) a prospectus supplement for the offering, issuance and sale by us of up to a maximum aggregate offering price of $100.0 million of our common stock that may be issued and sold, from time to time, under a sales agreement with Jefferies LLC ("Jefferies"), deemed to be “at the market offerings” (the "2020 Open Market Sales Agreement"). As of December 31, 2021, we had sold 23.3 million shares and received the maximum gross proceeds of $100.0 million pursuant to the 2020 Open Market Sales Agreement. In August 2021, we filed an additional prospectus supplement under the 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 an additional sales agreement we entered into with Jefferies (the "2021 Open Market Sales Agreement"), pursuant to which we may, from time to time, sell up to $150.0 million in shares of our common stock through Jefferies. We are not required to sell shares under the 2021 Open Market Sales Agreement. Pursuant to the 2021 Open Market Sales Agreement, Jefferies, as our sales agent, receives a commission of up to 3% of the gross sales price for shares of common stock sold under the 2021 Open Market Sales Agreement. During the three months ended September 30, 2022 we sold 32.6 million shares and received gross proceeds of $35.1 million at a weighted average sales price of approximately $1.08 per share under the 2021 Open Market Sales Agreement. During the nine months ended September 30, 2022 we sold 53.1 million shares and received gross proceeds of $54.0 million at a weighted average sales price of approximately $1.02 per share under the 2021 Open Market Sales Agreement. As of September 30, 2022, we have sold a total of 68.8 million shares and received aggregate gross proceeds of $79.0 million under the 2021 Open Market Sales Agreement.

Equity Incentive Plans

Equity Incentive Plans	9 Months Ended
	Sep. 30, 2022
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"), performance-based restricted stock units ("PRSUs") and our employee stock purchase program (the "ESPP") are recorded as operating expenses in our condensed statements of operations and comprehensive loss, as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Selling, general and administrative $ 1,373 $ 1,532 $ 6,102 $ 5,659 Research and development 461 730 2,557 2,909 Total $ 1,834 $ 2,262 $ 8,659 $ 8,568 As of September 30, 2022, the balance of inventory included in our condensed balance sheet includes $0.2 million stock-based compensation. During the three and nine months ending September 30, 2022, the amount of stock-based compensation released from inventory into cost of revenue was not material. As of September 30, 2022, 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 $ 11,082 2.6 RSU grants $ 3,030 3.0 ESPP $ 34 0.4 Stock Options A summary of our stock option activity and related information for the nine months ended September 30, 2022 is as follows (in thousands, except dollar amounts): Number of Shares Weighted-Average Balance at December 31, 2021 10,417 $ 7.00 Options granted 4,877 $ 0.88 Options exercised — $ — Options forfeited or canceled (1,454) $ 6.39 Balance at September 30, 2022 13,840 $ 4.91 Exercisable at September 30, 2022 7,801 $ 6.55 Restricted Stock Units A summary of our RSUs activity and related information for the nine months ended September 30, 2022 is as follows (in thousands, except dollar amounts): Number of Weighted-Average Non-vested restricted stock units at December 31, 2021 3,529 $ 2.04 Granted 2,012 $ 0.81 Vested (3,803) $ 1.29 Forfeited (306) $ 2.25 Non-vested restricted stock units at September 30, 2022 1,432 $ 2.25 Employee Stock Purchase Plan During the nine months ended September 30, 2022, 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 $0.63 per share resulting in proceeds to us of approximately $0.2 million. Issuance of Common Stock for Services

Restructuring

Restructuring	9 Months Ended
	Sep. 30, 2022
Restructuring and Related Activities [Abstract]
Restructuring	RESTRUCTURINGDuring 2021, we implemented restructuring plans in August 2021 and October 2021 following the receipt of a Complete Response Letter (“CRL”) from the U.S. FDA relating to our new drug application (“NDA”) for XPHOZAH® (tenapanor) and following the conclusion of an End of Review Type A meeting with the FDA, respectively. Both restructuring plans were substantially completed in December 2021 and most of the cash payments related to the reduction in workforce were disbursed prior to December 31, 2021.Impacted employees were eligible to receive severance benefits and additional Company funded COBRA premiums, contingent upon an impacted employee’s execution (and non-revocation) of a separation agreement, which included a general release of claims against us. In connection with restructuring, we incurred restructuring charges of $3.6 million during the three and nine months ended September 30, 2021 related to one-time termination notice and severance payments and other employee-related costs. We incurred no restructuring charges during the three and nine months ended September 30, 2022. We did not incur any significant contract termination costs pursuant to restructuring. Of the charges recognized as of September 30, 2021, $1.2 million was recorded in research and development expenses and $2.4 million was recorded in general and administrative expense in the accompanying statements of operations and comprehensive loss.

Net Loss Per Share

Net Loss Per Share	9 Months Ended
	Sep. 30, 2022
Earnings Per Share [Abstract]
Net Loss Per Share	NET LOSS PER SHAREBasic net loss per share is calculated by dividing net loss by the weighted-average number of common shares outstanding during the period, less shares subject to repurchase, 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 nine months ended September 30, 2022 and 2021, 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 September 30, Nine Months Ended September 30, Numerator: 2022 2021 2022 2021 Net loss $ (22,893) $ (43,587) $ (77,902) $ (121,931) Denominator: Weighted average common shares outstanding - basic and diluted 165,105 104,145 147,320 100,480 Net loss per share - basic and diluted $ (0.14) $ (0.42) $ (0.53) $ (1.21) For the periods presented, all common stock equivalents are excluded from the computation of diluted loss per share, as the result would be anti-dilutive, including the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Options to purchase common stock 13,882 11,962 13,410 12,127 Restricted stock units 1,542 983 3,145 999 ESPP shares issuable 180 273 169 241 Total 15,604 13,218 16,724 13,367

Contingencies

Contingencies	9 Months Ended
	Sep. 30, 2022
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 to represent all persons who purchased or otherwise acquired Ardelyx securities between August 6, 2020, and July 19, 2021. 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 an amended complaint on September 29, 2022. Defendant’s motion to dismiss the amended complaint is due December 2, 2022. A hearing on the anticipated motion to dismiss has not yet been scheduled. 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 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 violations of Section 14(a) of the Exchange Act, breaches of fiduciary duties, unjust enrichment, abuse of control, gross mismanagement, and waste, and seek 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. From time to time, we may be involved in legal proceedings arising in the ordinary course of business. As of September 30, 2022, 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 September 30, 2022.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2022
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTSOn October 31, 2022, we announced that our collaboration partner, KKC, submitted a New Drug Application to the Japanese Ministry of Health, Labour and Welfare for tenapanor for the improvement of hyperphosphatemia in adult patients with CKD on dialysis. This submission triggers KKC's obligation to make an aggregate of $35.0 million to us in milestone payments and payments under the 2022 Amendment. In accordance with the terms of the 2022 Amendment, we expect to receive these payments during the fourth quarter of 2022.

Organization and Basis of Pre_2

Organization and Basis of Presentation (Policies)	9 Months Ended
	Sep. 30, 2022
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, 2021. The results for the three and nine months ended September 30, 2022 are not necessarily indicative of results to be expected for the entire year ending December 31, 2022, 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, the 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.
Accounts Receivable	Accounts ReceivableAccounts receivable is reported net of allowances for returns, chargebacks and contractual off-invoice and prompt-pay discounts offered to our customers. Our estimate of the allowance for doubtful accounts is based on an evaluation of the aging of our receivables. Trade receivable balances are written off against the allowance when it is probable that the receivable will not be collected. To date, we have determined that an allowance for doubtful accounts is not required.
Inventory	Inventory We capitalize inventory costs associated with the production of our products after regulatory approval or when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Otherwise, such costs are expensed as research and development. Prior to the regulatory approval of drug product candidates, we incurred expenses for the manufacture of drug product that could potentially be available to support the commercial launch of our products or could be sold to our international partners under product supply agreements. We began to capitalize inventory costs associated with IBSRELA during the fourth quarter of 2021, when our intent to commercialize IBSRELA was established and we commenced preparation for the commercial launch of IBSRELA, which was when it was determined that the inventory had a probable future economic benefit. Inventory is stated at the lower of cost or estimated net realizable value with cost determined under the first-in first-out method. Inventory costs include the cost of materials, third-party contract manufacturing, third-party packaging services, freight, labor costs for personnel involved in the manufacturing process, and indirect overhead costs. We primarily use actual costs to determine the cost basis for inventory. The determination of whether inventory costs will be realizable requires management review of the expiration dates of IBSRELA compared to our forecasted sales. If actual market conditions are less favorable than projected by management, write-downs of inventory may be required, which would be recorded as cost of revenue in the condensed statement of operations and comprehensive loss. A portion of inventory is included in other assets on our condensed balance sheets as a non-current asset. The non-current balance represents product that is not expected to be sold or used within the next 12 months.
Product Sales, Net and Reserves for Variable Consideration	Product Sales, Net We account for our commercial product sales, net in accordance with Topic 606 - Revenue from Contracts with Customers . We received approval from the U.S. Food and Drug Administration (“FDA”) in September 2019 to market IBSRELA, the first and only sodium hydrogen exchanger 3 (“NHE3”) inhibitor for the treatment of irritable bowel syndrome with constipation ("IBS-C") in adults, in the United States ("U.S."). We began selling IBSRELA in the U.S. in March 2022. We distribute IBSRELA principally through major wholesalers, specialty pharmacies and group purchasing organizations ("GPOs") (collectively, our "Customers"). Our Customers subsequently sell IBSRELA to pharmacies and patients. Separately, we enter into arrangements with third parties that provide for government-mandated rebates, chargebacks and discounts. Revenue from product sales is recognized when our performance obligations are satisfied, which is when Customers obtain control of our product and occurs upon delivery. Reserves for Variable Consideration Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration, including discounts which may be settled in the form of off-invoice discounts, chargebacks, or rebates depending on the customer, wholesaler fees, group purchasing organization administrative fees, patient copay assistance programs, and estimated product returns. These estimates are based on the amounts earned or to be claimed for related sales and are classified as reductions of gross accounts receivable if settlement is expected to occur through a reduction in the amounts paid by our customers or a current liability if settlement is expected to occur through a payment from us. Where appropriate, these estimates are based on factors such as industry data and forecasted customer buying and payment patterns, our historical experience, current contractual and statutory requirements, specific known market events and trends. Overall, these reductions to gross sales reflect our best estimates of the amount of consideration to which we are entitled based on the terms of the contract. Variable consideration is included in the transaction price only to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. Actual amounts of consideration ultimately received may differ from our estimates. If actual results in the future vary from our estimates, we adjust these estimates, which would affect product revenue and earnings in the period such variances become known. As we gain more historical experience, estimates will be more heavily based on the expected utilization from historical data we have accumulated since the IBSRELA product launch. Rebates: Rebates include wholesaler fees, GPO fees, as well as mandated discounts under the Medicaid Drug Rebate Program ("Medicaid") and the Medicare Coverage Gap Program ("Medicare"). Estimates for rebates are recorded in the same period the related gross revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability which is included in accrued expenses on the condensed balance sheets. We estimate our Medicaid and Medicare rebates based upon the estimated payor mix, and statutory discount rates. Our estimates for payor mix are guided by payor information received from specialty pharmacies, expected utilization for wholesaler sales to pharmacies, and available industry payor information. Chargebacks: Chargebacks are discounts that occur when certain contracted purchasers purchase directly from our wholesalers at a discounted price. The wholesaler, in turn, charges back the difference between the price initially paid to us by the wholesaler and the discounted price paid to the wholesaler by the contracted purchaser. Amounts for estimated chargebacks are established in the same period that the related gross revenue is recognized, resulting in a reduction of product revenue and accounts receivable. The accrual for wholesaler chargebacks is estimated based on known chargeback rates, known sales to wholesalers, and estimated utilization by types of contracted purchasers. Discounts and Fees: Our payment terms are generally 30 to 60 days. Wholesalers, GPOs and specialty pharmacies are offered various forms of consideration, including off-invoice discounts which may be paid to GPOs and specialty pharmacies. Wholesalers and GPOs may also receive prompt pay discounts for payment within a specified period. We expect discounts to be earned when offered and therefore, we deduct the full amount of these discounts from product sales when revenue is recognized, resulting in a reduction of product revenue and accounts receivable.
Cost of Revenue	Cost of Revenue Cost of revenue consists of the cost of commercial goods sold to our Customers and international partners under product supply agreements, as well as royalty expense based on sales of tenapanor. We capitalize inventory costs associated with the production of our products after regulatory approval or when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized. Otherwise, such costs are expensed as research and development. A portion of the costs of IBSRELA units recognized as revenue during the three and nine months ended September 30, 2022 were expensed prior to the fourth quarter of 2021, at which time our intent to commercialize IBSRELA was established and we commenced preparation for the commercial launch of IBSRELA.
Non-cash Interest Expense on Deferred Royalty Obligation	Non-cash Interest Expense on Deferred Royalty Obligation The net proceeds we receive from the sale of certain future royalties are recorded as deferred royalty obligation related to the sale of future royalties on our balance sheets. As we earn royalties and remit those royalties pursuant to the agreement, the balance of the deferred royalty obligation will be effectively repaid over the life of agreement and non-cash interest expense related to the sale of future royalties is recorded using the effective interest method. To determine the amortization of our deferred royalty obligation, we are required to estimate the total amount of future royalty payments we expect to earn. There are a number of factors that could materially affect the amount and timing of royalty payments, most of which are not within our control. We periodically assess the amount of royalty payments we expect to receive which are subject to the agreement 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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements New Accounting Pronouncements - Recently Adopted We have adopted no new accounting pronouncements other than those disclosed in our most recent Annual Report on Form 10-K. Recent Accounting Pronouncements Not Yet Adopted There were various accounting standards and interpretations issued recently, none of which are expected to a have a material impact on our financial position, operations or cash flows.
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. 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 notes, 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 2018 Exit Fee and 2022 Exit Fee, as defined and discussed in Note 9. Derivative Liability , are classified as Level 3. The carrying amounts reflected in the condensed balance sheets for cash equivalents, short-term investments, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values at both September 30, 2022 and December 31, 2021, due to their short-term nature. 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 September 30, 2022 and December 31, 2021. 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 September 30, 2022 and is based on our current estimates of future royalties and commercialization milestones expected to be paid to us by KKC 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)	9 Months Ended
	Sep. 30, 2022
Cash and Cash Equivalents [Abstract]
Schedule of Securities Classified as Cash, Cash Equivalents and Investments	Securities classified as cash, cash equivalents and investments as of September 30, 2022 and December 31, 2021 are summarized below (in thousands): September 30, 2022 Gross Unrealized Amortized Cost Gains Losses Fair Value Cash and cash equivalents: Cash $ 652 $ — $ — $ 652 Money market funds 60,976 — — 60,976 Total cash and cash equivalents 61,628 — — 61,628 Short-term investments: Commercial paper $ 20,616 $ — $ (78) $ 20,538 U.S. government-sponsored agency bonds 1,480 — (1) 1,479 Corporate bonds 1,005 — (9) 996 U.S. treasury notes 6,008 — (26) 5,982 Total short-term investments 29,109 — (114) 28,995 Total cash equivalents and investments $ 90,737 $ — $ (114) $ 90,623 December 31, 2021 Gross Unrealized Amortized Cost Gains Losses Fair Value Cash and cash equivalents: Cash $ 1,253 $ — $ — $ 1,253 Money market funds 71,175 — — 71,175 Total cash and cash equivalents 72,428 — — 72,428 Short-term investments Commercial paper $ 31,936 $ 1 $ (2) $ 31,935 Corporate bonds 7,025 — (3) 7,022 Asset backed securities 5,306 — (2) 5,304 Total short-term investments 44,267 1 (7) 44,261 Total cash equivalents and investments $ 116,695 $ 1 $ (7) $ 116,689

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Summary of Fair Value of Financial Assets and Liabilities Measured or Disclosed 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): September 30, 2022 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 60,976 $ 60,976 $ — $ — Commercial paper 20,538 — 20,538 — U.S. government-sponsored agency bonds 1,479 — 1,479 — Corporate bonds 996 — 996 — U.S. treasury notes 5,982 — 5,982 — Total $ 89,971 $ 60,976 $ 28,995 $ — Liabilities: Derivative liabilities for exit fees $ 1,127 $ — $ — $ 1,127 Total $ 1,127 $ — $ — $ 1,127 December 31, 2021 Total Level 1 Level 2 Level 3 Assets: Money market funds $ 71,175 $ 71,175 $ — $ — Commercial paper 31,935 — 31,935 — Corporate bonds 7,022 — 7,022 — Asset-backed securities 5,304 — 5,304 — Total $ 115,436 $ 71,175 $ 44,261 $ — Liabilities: Derivative liability for exit fee $ 698 $ — $ — $ 698 Total $ 698 $ — $ — $ 698

Inventory (Tables)

Inventory (Tables)	9 Months Ended
	Sep. 30, 2022
Inventory Disclosure [Abstract]
Schedule of Inventory	Inventory consisted of the following (in thousands): September 30, 2022 Raw materials $ 5,798 Work in process 2,907 Finished goods 1,069 Total $ 9,774 Reported as: Inventory $ 1,250 Other assets 8,524 Total $ 9,774

Product Revenue, Net (Tables)

Product Revenue, Net (Tables)	9 Months Ended
	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
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 Other Fees, Copay and Returns Total Balance as of December 31, 2021 $ — $ — $ — $ — Activity related to 2022 sales 358 1,158 1,115 2,631 Credits/deductions issued (250) (438) (576) (1,264) Balance as of September 30, 2022 $ 108 $ 720 $ 539 $ 1,367

Collaboration and Licensing A_2

Collaboration and Licensing Agreements (Tables)	9 Months Ended
	Sep. 30, 2022
Collaboration and Licensing Agreements
Schedule of Changes in Deferred Revenue	The following tables present changes in our current and non-current deferred revenue balances during the reporting period. The September 30, 2022 deferred revenue balance is attributable entirely to the 2017 KKC Agreement, while the current September 30, 2021 deferred revenue balance is attributable to the 2019 KKC Agreement and the non-current September 30, 2021 deferred revenue balance is attributable to the 2017 KKC Agreement (in thousands): Deferred revenue - current 2022 2021 Balance at January 1, $ — $ 4,177 Increases due to amounts reclassified from non-current, to be recognized in the next twelve months 3,961 Increases to amounts invoiced, for which cash has not yet been received 42 — Decreases due to revenue recognized in the period for which cash has been received — (3,650) Balance at September 30, $ 4,003 $ 527 Deferred revenue - non-current 2022 2021 Balance at January 1, $ 4,727 $ — Increases due to cash received during the period 7,694 2,947 Increases to amounts invoiced, for which cash has not yet been received 100 — Decreases due to amounts reclassified as current, to be recognized in the next twelve months (3,961) — Balance at September 30, $ 8,560 $ 2,947

Borrowing (Tables)

Borrowing (Tables)	9 Months Ended
	Sep. 30, 2022
Debt Disclosure [Abstract]
Schedule of Future Debt Payment Obligations	As of September 30, 2022, our future payment obligations related to the 2022 Loan, excluding interest payments and the 2022 final fee, are as follows (in thousands): Total repayment obligations $ 28,862 Less: Unamortized discount (1,185) Less: Unaccreted value of final fee (1,136) Long-term debt 26,541 Less: Current portion of long-term debt (26,541) Long-term debt, net of current portion $ —

Derivative Liability (Tables)

Derivative Liability (Tables)	9 Months Ended
	Sep. 30, 2022
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Changes in Fair Value of Derivative Liability	Changes in the fair value of our exit fee derivative liabilities recurring measurements included in Level 3 of the fair value hierarchy are presented as other income, net in our statements of operations and were as follows for the three and nine months ended September 30, 2022 and 2021 (in thousands): 2022 2021 Balance at January 1, $ 698 $ 1,376 2022 Exit Fee addition at fair value 375 — Changes in estimated fair value: 2018 Exit Fee $ (4) $ (696) 2022 Exit Fee $ 58 $ — Balance at September 30, $ 1,127 $ 680

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2022
Leases [Abstract]
Summary 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 September 30, 2022 December 31, 2021 Right-of-use assets $ 10,182 $ 12,752 Current portion of lease liabilities 3,791 3,492 Operating lease liability, net of current portion 6,878 9,748 Total $ 10,669 $ 13,240 Weighted-average remaining life (years) 2.7 3.4 Weighted-average discount rate 6.8 % 6.9 %
Summary of Lease Costs	Lease costs, which are included in operating expenses in our statements of operations, were as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Operating lease expense $ 1,064 $ 1,096 $ 3,192 $ 2,606 Cash paid for operating lease $ 1,072 $ 829 $ 3,194 $ 2,383
Summary 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 September 30, 2022 (in thousands): Remainder of 2022 $ 1,097 2023 4,440 2024 4,589 2025 1,321 2026 253 Total undiscounted operating lease payments 11,700 Imputed interest expenses (1,031) Total operating lease liabilities 10,669 Less: Current portion of operating lease liability (3,791) Operating lease liability, net of current portion $ 6,878

Equity Incentive Plans (Tables)

Equity Incentive Plans (Tables)	9 Months Ended
	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Summary of Stock-Based Compensation Expense Recognized	Stock-based compensation expense recognized for stock options, restricted stock units ("RSUs"), performance-based restricted stock units ("PRSUs") and our employee stock purchase program (the "ESPP") are recorded as operating expenses in our condensed statements of operations and comprehensive loss, as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Selling, general and administrative $ 1,373 $ 1,532 $ 6,102 $ 5,659 Research and development 461 730 2,557 2,909 Total $ 1,834 $ 2,262 $ 8,659 $ 8,568
Summary of Total Unrecognized Stock-Based Compensation Expense, Net of Estimated Forfeitures	As of September 30, 2022, 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 $ 11,082 2.6 RSU grants $ 3,030 3.0 ESPP $ 34 0.4
Schedule of Stock Option Activity	A summary of our stock option activity and related information for the nine months ended September 30, 2022 is as follows (in thousands, except dollar amounts): Number of Shares Weighted-Average Balance at December 31, 2021 10,417 $ 7.00 Options granted 4,877 $ 0.88 Options exercised — $ — Options forfeited or canceled (1,454) $ 6.39 Balance at September 30, 2022 13,840 $ 4.91 Exercisable at September 30, 2022 7,801 $ 6.55
Schedule of Restricted Stock Units Activity	A summary of our RSUs activity and related information for the nine months ended September 30, 2022 is as follows (in thousands, except dollar amounts): Number of Weighted-Average Non-vested restricted stock units at December 31, 2021 3,529 $ 2.04 Granted 2,012 $ 0.81 Vested (3,803) $ 1.29 Forfeited (306) $ 2.25 Non-vested restricted stock units at September 30, 2022 1,432 $ 2.25

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2022
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 September 30, Nine Months Ended September 30, Numerator: 2022 2021 2022 2021 Net loss $ (22,893) $ (43,587) $ (77,902) $ (121,931) Denominator: Weighted average common shares outstanding - basic and diluted 165,105 104,145 147,320 100,480 Net loss per share - basic and diluted $ (0.14) $ (0.42) $ (0.53) $ (1.21)
Schedule of Anti-Dilutive Securities Not Considered in Diluted Net Loss Per Common Share Calculation	For the periods presented, all common stock equivalents are excluded from the computation of diluted loss per share, as the result would be anti-dilutive, including the following (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2022 2021 2022 2021 Options to purchase common stock 13,882 11,962 13,410 12,127 Restricted stock units 1,542 983 3,145 999 ESPP shares issuable 180 273 169 241 Total 15,604 13,218 16,724 13,367

Organization and Basis of Pre_3

Organization and Basis of Presentation (Details) $ in Thousands	1 Months Ended	9 Months Ended
	Jun. 30, 2015 USD ($)	Sep. 30, 2022 USD ($) segment	Dec. 31, 2021 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of segments | segment		1
Cash and investments		$ 90,623	$ 116,689
Accumulated deficit		790,832	712,930
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable		5,208	502
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		$ 12,400
Minimum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payment terms		30 days
Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payment terms		60 days
Collaborators
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable		$ 500	$ 500
Commercial customers
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable		$ 4,700

Cash, Cash Equivalents and In_3

Cash, Cash Equivalents and Investments - Securities Classified as Cash, Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Cash and cash equivalents:
Fair Value	$ 61,628	$ 72,428
Short-term investments:
Amortized Cost	29,109	44,267
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(114)	(7)
Fair Value	28,995	44,261
Amortized Cost	90,737	116,695
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(114)	(7)
Fair Value	90,623	116,689
Commercial paper
Short-term investments:
Amortized Cost	20,616	31,936
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(78)	(2)
Fair Value	20,538	31,935
U.S. government-sponsored agency bonds
Short-term investments:
Amortized Cost	1,480
Gross Unrealized Gains	0
Gross Unrealized Losses	(1)
Fair Value	1,479
Corporate bonds
Short-term investments:
Amortized Cost	1,005	7,025
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(9)	(3)
Fair Value	996	7,022
U.S. treasury notes
Short-term investments:
Amortized Cost	6,008
Gross Unrealized Gains	0
Gross Unrealized Losses	(26)
Fair Value	5,982
Asset backed securities
Short-term investments:
Amortized Cost		5,306
Gross Unrealized Gains		0
Gross Unrealized Losses		(2)
Fair Value		5,304
Cash
Cash and cash equivalents:
Fair Value	652	1,253
Money market funds
Cash and cash equivalents:
Fair Value	$ 60,976	$ 71,175

Cash, Cash Equivalents and In_4

Cash, Cash Equivalents and Investments - Narrative (Details)	9 Months Ended
	Sep. 30, 2022 investment
Cash and Cash Equivalents [Abstract]
Short-term available-for-sale securities contractual maturities, maximum	1 year
Number of investments in unrealized loss position	0

Fair Value Measurements (Detail

Fair Value Measurements (Details) - Recurring - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Assets:
Assets, fair value	$ 89,971	$ 115,436
Liabilities:
Liabilities, fair value	1,127	698
Derivative liabilities for exit fees
Liabilities:
Liabilities, fair value	1,127	698
Money market funds
Assets:
Assets, fair value	60,976	71,175
Commercial paper
Assets:
Assets, fair value	20,538	31,935
U.S. government-sponsored agency bonds
Assets:
Assets, fair value	1,479
Corporate bonds
Assets:
Assets, fair value	996	7,022
U.S. treasury notes
Assets:
Assets, fair value	5,982
Asset backed securities
Assets:
Assets, fair value		5,304
Level 1
Assets:
Assets, fair value	60,976	71,175
Liabilities:
Liabilities, fair value	0	0
Level 1 | Derivative liabilities for exit fees
Liabilities:
Liabilities, fair value	0	0
Level 1 | Money market funds
Assets:
Assets, fair value	60,976	71,175
Level 1 | Commercial paper
Assets:
Assets, fair value	0	0
Level 1 | U.S. government-sponsored agency bonds
Assets:
Assets, fair value	0
Level 1 | Corporate bonds
Assets:
Assets, fair value	0	0
Level 1 | U.S. treasury notes
Assets:
Assets, fair value	0
Level 1 | Asset backed securities
Assets:
Assets, fair value		0
Level 2
Assets:
Assets, fair value	28,995	44,261
Liabilities:
Liabilities, fair value	0	0
Level 2 | Derivative liabilities for exit fees
Liabilities:
Liabilities, fair value	0	0
Level 2 | Money market funds
Assets:
Assets, fair value	0	0
Level 2 | Commercial paper
Assets:
Assets, fair value	20,538	31,935
Level 2 | U.S. government-sponsored agency bonds
Assets:
Assets, fair value	1,479
Level 2 | Corporate bonds
Assets:
Assets, fair value	996	7,022
Level 2 | U.S. treasury notes
Assets:
Assets, fair value	5,982
Level 2 | Asset backed securities
Assets:
Assets, fair value		5,304
Level 3
Assets:
Assets, fair value	0	0
Liabilities:
Liabilities, fair value	1,127	698
Level 3 | Derivative liabilities for exit fees
Liabilities:
Liabilities, fair value	1,127	698
Level 3 | Money market funds
Assets:
Assets, fair value	0	0
Level 3 | Commercial paper
Assets:
Assets, fair value	0	0
Level 3 | U.S. government-sponsored agency bonds
Assets:
Assets, fair value	0
Level 3 | Corporate bonds
Assets:
Assets, fair value	0	0
Level 3 | U.S. treasury notes
Assets:
Assets, fair value	$ 0
Level 3 | Asset backed securities
Assets:
Assets, fair value		$ 0

Inventory - Schedule (Details)

Inventory - Schedule (Details) $ in Thousands	Sep. 30, 2022 USD ($)
Inventory [Line Items]
Raw materials	$ 5,798
Work in process	2,907
Finished goods	1,069
Total	9,774
Inventories
Inventory [Line Items]
Total	1,250
Other Assets
Inventory [Line Items]
Total	$ 8,524

Inventory - Narrative (Details)

Inventory - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Inventory Disclosure [Abstract]
Prepaid commercial manufacturing	$ 16,145	$ 9,406
Prepaid commercial manufacturing, noncurrent	$ 3,800

Product Revenue, Net - Narrativ

Product Revenue, Net - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Revenue	$ 4,986,000	$ 1,173,000	$ 7,980,000	$ 9,068,000
Contract with customer product sales gross to net accruals		0		0
Gross product revenue | Customer | AmerisourceBergen Drug Corporation
Disaggregation of Revenue [Line Items]
Concentration risk (percent)	26.40%		28.90%
Gross product revenue | Customer | Cardinal Health
Disaggregation of Revenue [Line Items]
Concentration risk (percent)	25.20%		24.20%
Gross product revenue | Customer | McKesson Corporation
Disaggregation of Revenue [Line Items]
Concentration risk (percent)	20.20%		20.90%
IBSRELA
Disaggregation of Revenue [Line Items]
Revenue	$ 4,900,000		$ 6,900,000
Product sales, net
Disaggregation of Revenue [Line Items]
Revenue	$ 4,885,000	$ 0	$ 6,899,000	$ 0

Product Revenue, Net - Gross-to

Product Revenue, Net - Gross-to-Net Sales Accruals (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($)
Gross-to-net sales accruals and reserves
Beginning balance	$ 0
Activity related to 2022 sales	2,631
Credits/deductions issued	(1,264)
Ending balance	1,367
Discounts and Chargebacks
Gross-to-net sales accruals and reserves
Beginning balance	0
Activity related to 2022 sales	358
Credits/deductions issued	(250)
Ending balance	108
Rebates
Gross-to-net sales accruals and reserves
Beginning balance	0
Activity related to 2022 sales	1,158
Credits/deductions issued	(438)
Ending balance	720
Other Fees, Copay and Returns
Gross-to-net sales accruals and reserves
Beginning balance	0
Activity related to 2022 sales	1,115
Credits/deductions issued	(576)
Ending balance	$ 539

Collaboration and Licensing A_3

Collaboration and Licensing Agreements - Narrative (Details) $ in Millions, ¥ in Billions	1 Months Ended					3 Months Ended		9 Months Ended			59 Months Ended
	Nov. 30, 2019 USD ($) segment item	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Nov. 30, 2017 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2022 CAD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2022 JPY (¥)	Apr. 11, 2022 USD ($) payment_tranche
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						$ 4,986,000	$ 1,173,000	$ 7,980,000		$ 9,068,000
Cost of revenue						732,000	0	955,000		1,000,000
Licensing revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						9,000	2,000	23,000		5,007,000
Product supply revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						92,000	285,000	1,058,000		411,000
2019 KKC Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						0	900,000	0		3,700,000
2019 KKC Agreement | KKC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront license fees	$ 10,000,000
First installment of upfront license fees	$ 5,000,000
Term of payment of license fee, first installment	30 days
Second installment of upfront license fees	$ 5,000,000
Term of agreement	2 years
Number of amendments | segment	3
2017 KKC Agreement | Licensing revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						0	0	0		5,000,000	$ 10,000,000
2017 KKC Agreement | Product supply revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						83,000	300,000	1,000,000		400,000
2017 KKC Agreement | KKC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront license fees				$ 30,000,000
Potential development milestones				$ 55,000,000
Potential commercialization milestones						58,700,000		58,700,000			58,700,000	¥ 8.5
Fee receivable for reduction in royalty rate													$ 40,000,000
Number of payment tranches for fee receivable for reduction in royalty rate | payment_tranche													2
Fosun Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue							0			0
Fosun Agreement | Product supply revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						9,000		9,000
Fosun Agreement | Fosun Pharma
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential development milestones						3,000,000		3,000,000			3,000,000
Upfront payment received			$ 12,000,000
Potential development and commercialization milestones								$ 113,000,000
Threshold percentage of net sales for tiered royalties								20%	20%
Knight Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue							2,000			7,000
Knight Agreement | Licensing revenue
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue						9,000		$ 23,000
Knight Agreement | Knight
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Potential development milestones						700,000		700,000			700,000
Upfront payment received		$ 2,300,000
Potential development and commercialization milestones								16,100,000	$ 22.2
AZ Termination Agreement | AstraZeneca
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					$ 75,000,000
Aggregate cost of revenue recognized						12,400,000		12,400,000			12,400,000
Aggregate amount paid						11,600,000		11,600,000			$ 11,600,000
Cost of revenue						$ 500,000	$ 0	$ 800,000		$ 1,000,000
Minimum | 2019 KKC Agreement | KKC
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of separate collaborative agreements | item	1

Collaboration and Licensing A_4

Collaboration and Licensing Agreements - Deferred Revenue (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Deferred revenue - current
Beginning balance	$ 0
Ending balance	4,003
Deferred revenue - non-current
Beginning balance	4,727
Ending balance	8,560
2017 KKC Agreement
Deferred revenue - current
Beginning balance	0
Increases due to amounts reclassified from non-current, to be recognized in the next twelve months	3,961
Increases to amounts invoiced, for which cash has not yet been received	42
Decreases due to revenue recognized in the period for which cash has been received	0
Ending balance	4,003
Deferred revenue - non-current
Beginning balance	4,727
Increases due to cash received during the period	7,694
Increases to amounts invoiced, for which cash has not yet been received	100
Decreases due to amounts reclassified as current, to be recognized in the next twelve months	(3,961)
Ending balance	$ 8,560
2019 KKC Agreement
Deferred revenue - current
Beginning balance		$ 4,177
Increases due to amounts reclassified from non-current, to be recognized in the next twelve months
Increases to amounts invoiced, for which cash has not yet been received		0
Decreases due to revenue recognized in the period for which cash has been received		(3,650)
Ending balance		527
Deferred revenue - non-current
Beginning balance		0
Increases due to cash received during the period		2,947
Increases to amounts invoiced, for which cash has not yet been received		0
Decreases due to amounts reclassified as current, to be recognized in the next twelve months		0
Ending balance		$ 2,947

Deferred Royalty Obligation R_2

Deferred Royalty Obligation Related To The Sale Of Future Royalties (Details) - USD ($)		3 Months Ended		9 Months Ended
	Jun. 28, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Jun. 30, 2022
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Amortization of the deferred royalty obligation		$ 831,000	$ 0	$ 841,000	$ 0
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
Upfront payment	10,000,000					$ 10,000,000
Payment to be received	$ 5,000,000
Transaction costs		$ 400,000		$ 400,000
Amortization, effective interest rate, percent				34.40%

Borrowing - Narrative (Details)

Borrowing - Narrative (Details) - USD ($)	Feb. 23, 2022	Sep. 30, 2022	May 31, 2018	May 16, 2018
Debt Instrument [Line Items]
Principal outstanding		$ 28,862,000
2018 Term Loan | Term Loan
Debt Instrument [Line Items]
Term loan face amount				$ 50,000,000
Principal outstanding				$ 25,000,000
2022 Term Loan | Term Loan
Debt Instrument [Line Items]
Final fee due upon maturity, acceleration, prepayment, or termination (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	6 months
Loan agreement covenant, net product revenue as percentage of outstanding loan balance, minimum	60%
Additional default interest rate	4%
2022 Term Loan | Term Loan | Prior to first anniversary of closing date
Debt Instrument [Line Items]
Prepayment premium (as a percent)	3%
2022 Term Loan | Term Loan | After first anniversary through second anniversary of closing date
Debt Instrument [Line Items]
Prepayment premium (as a percent)	2%
2022 Term Loan | Term Loan | After second anniversary to maturity date
Debt Instrument [Line Items]
Prepayment premium (as a percent)	1%
2022 Term Loan | Term Loan | LIBOR
Debt Instrument [Line Items]
Floating per annum rate (percent)	7.95%
Addition to floating per annum rate (percent)	0.10%
Term Loan A | Term Loan
Debt Instrument [Line Items]
Proceeds from the sale of future royalties, net of issuance costs	$ 27,500,000
Payment term	36 months
Closing fee	$ 200,000
Term Loan B | Term Loan
Debt Instrument [Line Items]
Remaining funding based on milestone achievement	22,500,000
Future obligation upon loan funding or other events	$ 100,000
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 (percent)	2%
Exit fee, net product revenue threshold	$ 100,000,000
Exit fee, term (in years)	10 years

Borrowing - Future Payment Obli

Borrowing - Future Payment Obligations (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Debt Disclosure [Abstract]
Total repayment obligations	$ 28,862
Less: Unamortized discount	(1,185)
Less: Unaccreted value of final fee	(1,136)
Long-term debt	26,541
Less: Current portion of long-term debt	(26,541)	$ (32,264)
Long-term debt, net of current portion	$ 0

Derivative Liability - Narrativ

Derivative Liability - Narrative (Details) - USD ($) $ in Millions	Feb. 23, 2022	Sep. 30, 2022	Dec. 31, 2021	May 31, 2018
2018 Exit Fee
Derivative [Line Items]
Agreed amount for exit fee upon change of control or regulatory approval				$ 1.5
Estimated fair value		$ 0.7	$ 0.7
2018 Exit Fee | Level 3
Derivative [Line Items]
Fair value analysis, percentage change in probability of occurrence		10%
Fair value analysis, effect on fair value based on 10% change in probability of occurrence		$ 0.1
2022 Exit Fee
Derivative [Line Items]
Estimated fair value		$ 0.4
Exit fee (percent)	2%
Exit fee, net product revenue threshold	$ 100
2022 Exit Fee | Level 3
Derivative [Line Items]
Fair value analysis, percentage change in probability of occurrence		10%

Derivative Liability - Changes

Derivative Liability - Changes in Fair Value (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
2018 Exit Fee
Change in Fair Value of Derivative Liability
Beginning balance	$ 700
Ending balance	700
2022 Exit Fee
Change in Fair Value of Derivative Liability
Ending balance	400
Exit Fee derivative liability
Change in Fair Value of Derivative Liability
Beginning balance	698	$ 1,376
2022 Exit Fee addition at fair value	375	0
Ending balance	1,127	680
Exit Fee derivative liability | 2018 Exit Fee
Change in Fair Value of Derivative Liability
Changes in estimated fair value	(4)	(696)
Exit Fee derivative liability | 2022 Exit Fee
Change in Fair Value of Derivative Liability
Changes in estimated fair value	$ 58	$ 0

Leases - Additional Details of

Leases - Additional Details of Facility Leases (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Right-of-use assets and lease liabilities
Right-of-use assets	$ 10,182	$ 12,752
Current portion of lease liabilities	3,791	3,492
Operating lease liability, net of current portion	6,878	9,748
Total operating lease liabilities	$ 10,669	$ 13,240
Additional details
Weighted-average remaining life (years)	2 years 8 months 12 days	3 years 4 months 24 days
Weighted-average discount rate	6.80%	6.90%

Leases - Lease Costs (Details)

Leases - Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Lease costs
Operating lease expense	$ 1,064	$ 1,096	$ 3,192	$ 2,606
Cash paid for operating lease	$ 1,072	$ 829	$ 3,194	$ 2,383

Leases - Undiscounted Cash Paym

Leases - Undiscounted Cash Payment Obligations (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Undiscounted cash payment obligations
Remainder of 2022	$ 1,097
2023	4,440
2024	4,589
2025	1,321
2026	253
Total undiscounted operating lease payments	11,700
Imputed interest expenses	(1,031)
Total operating lease liabilities	10,669	$ 13,240
Less: Current portion of operating lease liability	(3,791)	(3,492)
Operating lease liability, net of current portion	$ 6,878	$ 9,748

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, shares in Millions	3 Months Ended	9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	Aug. 31, 2021	Jul. 31, 2020
Subsidiary, Sale of Stock [Line Items]
Proceeds from issuance of common stock in at the market offering, net of issuance costs		$ 52,845,000	$ 67,189,000
Common stock
Subsidiary, Sale of Stock [Line Items]
Maximum aggregate offering price						$ 250,000,000
2020 Open Market Sales Agreement
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock in at the market offering (in shares)				23.3
Proceeds from issuance of common stock in at the market offering, net of issuance costs				$ 100,000,000
2020 Open Market Sales Agreement | Common stock
Subsidiary, Sale of Stock [Line Items]
Maximum aggregate offering price						$ 100,000,000
2021 Open Market Sales Agreement
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock in at the market offering (in shares)	32.6	53.1
Proceeds from issuance of common stock in at the market offering, net of issuance costs	$ 35,100,000	$ 54,000,000
Commission on sale of stock per agreement (percent)		3%
Weighted-average sales price per share (in dollars per share)	$ 1.08	$ 1.02
Total of shares sold	68.8	68.8
Total of gross proceeds	$ 79,000,000	$ 79,000,000
2021 Open Market Sales Agreement | Common stock
Subsidiary, Sale of Stock [Line Items]
Maximum aggregate offering price					$ 150,000,000

Equity Incentive Plans - Stock-

Equity Incentive Plans - Stock-Based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Stock-based Compensation [Line Items]
Stock-based compensation expense	$ 1,834	$ 2,262	$ 8,659	$ 8,568
Selling, general and administrative
Stock-based Compensation [Line Items]
Stock-based compensation expense	1,373	1,532	6,102	5,659
Research and development
Stock-based Compensation [Line Items]
Stock-based compensation expense	$ 461	$ 730	$ 2,557	$ 2,909

Equity Incentive Plans - Narrat

Equity Incentive Plans - Narrative (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2022 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation benefits | $	$ 0.2
Board of directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of common stock for services (in shares) | shares	700,000
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) | shares	300,000
Purchase price (in dollars per share) | $ / shares	$ 0.63
Proceeds from ESPP | $	$ 0.2

Equity Incentive Plans - Unreco

Equity Incentive Plans - Unrecognized Stock-Based Compensation (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($)
Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Expense	$ 11,082
Average Remaining Vesting Period (Years)	2 years 7 months 6 days
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Expense	$ 3,030
Average Remaining Vesting Period (Years)	3 years
ESPP shares issuable
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized Compensation Expense	$ 34
Average Remaining Vesting Period (Years)	4 months 24 days

Equity Incentive Plans - Stock

Equity Incentive Plans - Stock Options (Details)	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Number of Shares
Options outstanding balance, beginning (in shares) | shares	10,417,000
Options granted (in shares) | shares	4,877,000
Options exercised (in shares) | shares	0
Options forfeited or canceled (in shares) | shares	(1,454,000)
Options outstanding balance, ending (in shares) | shares	13,840,000
Options exercisable (in shares) | shares	7,801,000
Weighted-Average Exercise Price per Share
Options outstanding balance, beginning (in dollars per share) | $ / shares	$ 7
Options granted (in dollars per share) | $ / shares	0.88
Options exercised (in dollars per share) | $ / shares	0
Options forfeited or canceled (in dollars per share) | $ / shares	6.39
Options outstanding balance, ending (in dollars per share) | $ / shares	4.91
Options exercisable (in dollars per share) | $ / shares	$ 6.55

Equity Incentive Plans - Restri

Equity Incentive Plans - Restricted Stock Units (Details) - Restricted stock units shares in Thousands	9 Months Ended
	Sep. 30, 2022 $ / shares shares
Number of RSUs
Outstanding balance, beginning (in shares) | shares	3,529
Granted (in shares) | shares	2,012
Vested (in shares) | shares	(3,803)
Forfeited (in shares) | shares	(306)
Outstanding balance, ending (in shares) | shares	1,432
Weighted-Average Grant Date Fair Value Per Share
Outstanding balance, beginning (in dollars per share) | $ / shares	$ 2.04
Granted (in dollars per share) | $ / shares	0.81
Vested (in dollars per share) | $ / shares	1.29
Forfeited (in dollars per share) | $ / shares	2.25
Outstanding balance, ending (in dollars per share) | $ / shares	$ 2.25

Restructuring (Details)

Restructuring (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0	$ 3.6	$ 0	$ 3.6
Research and development expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges		1.2		1.2
General and administrative expense
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 2.4		$ 2.4

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		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Numerator:
Net loss	$ (22,893)	$ (43,587)	$ (77,902)	$ (121,931)
Denominator:
Weighted average common shares outstanding - basic (in shares)	165,104,789	104,144,606	147,319,818	100,480,156
Weighted average common shares outstanding - diluted (in shares)	165,104,789	104,144,606	147,319,818	100,480,156
Net loss per share - basic (in dollars per share)	$ (0.14)	$ (0.42)	$ (0.53)	$ (1.21)
Net loss per share - diluted (in dollars per share)	$ (0.14)	$ (0.42)	$ (0.53)	$ (1.21)

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Anti Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share (in shares)	15,604	13,218	16,724	13,367
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)	13,882	11,962	13,410	12,127
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)	1,542	983	3,145	999
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)	180	273	169	241

Contingencies (Details)

Contingencies (Details)			4 Months Ended
	Aug. 12, 2022 defendant claim	Jul. 19, 2022 claim	Mar. 29, 2022 claim defendant	Sep. 30, 2022 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

Subsequent Events (Details)

Subsequent Events (Details) $ in Millions	Oct. 31, 2022 USD ($)
Subsequent event | KKC | Licensing revenue
Subsequent Event [Line Items]
Proceeds from milestone payments	$ 35