Eiger BioPharmaceuticals (EIGRQ) 10-Q 4 Aug 22 2022 Q2 Quarterly report Financial data

Cover

Cover - shares	6 Months Ended
	Jun. 30, 2022	Aug. 01, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2022
Document Fiscal Year Focus	2022
Document Transition Report	false
Entity File Number	001-36183
Entity Registrant Name	Eiger BioPharmaceuticals, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	33-0971591
Entity Address, Address Line One	2155 Park Boulevard
Entity Address, City or Town	Palo Alto
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94306
City Area Code	650
Local Phone Number	272-6138
Title of 12(b) Security	Common Stock (par value $0.001 per share)
Trading Symbol	EIGR
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		43,966,783
Amendment Flag	false
Document Fiscal Period Focus	Q2
Entity Central Index Key	0001305253
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 36,572	$ 22,221
Short-term debt securities	105,220	66,594
Accounts receivable, net	1,038	2,576
Inventories	2,876	2,612
Prepaid expenses and other current assets	11,997	9,361
Total current assets	157,703	103,364
Long-term debt securities	0	17,262
Property and equipment, net	525	613
Operating lease right-of-use assets	385	653
Other assets	5,078	4,510
Total assets	163,691	126,402
Current liabilities:
Accounts payable	9,945	7,765
Accrued liabilities	11,466	13,699
Current portion of operating lease liabilities	436	628
Debt, current portion	0	7,809
Total current liabilities	21,847	29,901
Debt, net of current portion	38,916	23,986
Operating lease liabilities	3	116
Total liabilities	60,766	54,003
Stockholders’ equity:
Common stock	44	35
Additional paid-in capital	488,586	412,930
Accumulated other comprehensive loss	(761)	(149)
Accumulated deficit	(384,944)	(340,417)
Total stockholders’ equity	102,925	72,399
Total liabilities and stockholders’ equity	$ 163,691	$ 126,402

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenues [Abstract]
Total revenue	$ 4,091,000	$ 2,097,000	$ 6,764,000	$ 5,743,000
Costs and operating expenses:
Cost of sales	151,000	270,000	261,000	323,000
Research and development	16,993,000	14,302,000	34,563,000	28,144,000
Selling, general and administrative	7,027,000	5,886,000	13,840,000	11,450,000
Total costs and operating expenses	24,171,000	20,458,000	48,664,000	39,917,000
Loss from operations	(20,080,000)	(18,361,000)	(41,900,000)	(34,174,000)
Interest expense	(934,000)	(880,000)	(1,820,000)	(1,765,000)
Interest income	221,000	33,000	266,000	84,000
Other (expense) income, net	(1,074,000)	45,000	(1,047,000)	45,959,000
(Loss) income before provision for income taxes	(21,867,000)	(19,163,000)	(44,501,000)	10,104,000
Provision for income taxes	17,000	11,000	26,000	30,000
Net (loss) income	$ (21,884,000)	$ (19,174,000)	$ (44,527,000)	$ 10,074,000
Net (loss) income per common share:
Basic (in USD per share)	$ (0.51)	$ (0.57)	$ (1.14)	$ 0.30
Diluted (in USD per share)	$ (0.51)	$ (0.57)	$ (1.14)	$ 0.29
Weighted-average common shares outstanding:
Basic (in shares)	43,059,809	33,932,127	39,178,043	33,909,637
Diluted (in shares)	43,059,809	33,932,127	39,178,043	34,156,877
Product revenue, net
Revenues [Abstract]
Total revenue	$ 3,341,000	$ 2,097,000	$ 6,014,000	$ 5,743,000
Other revenue
Revenues [Abstract]
Total revenue	$ 750,000	$ 0	$ 750,000	$ 0

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive (Loss) Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (21,884)	$ (19,174)	$ (44,527)	$ 10,074
Other comprehensive (loss) income:
Unrealized (loss) gain on available-for-sale debt securities, net	(239)	(1)	(612)	2
Comprehensive (loss) income	$ (22,123)	$ (19,175)	$ (45,139)	$ 10,076

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders’ Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance, beginning of period (in shares) at Dec. 31, 2020		33,878,486
Balance, beginning of period at Dec. 31, 2020	$ 95,035	$ 34	$ 401,509	$ (8)	$ (306,500)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		19,150
Issuance of common stock upon exercise of stock options	166		166
Vesting of common stock issued under Product Development Agreement	53		53
Issuance of common stock upon ESPP purchase (in shares)		19,928
Issuance of common stock upon ESPP purchase	136		136
Issuance of common stock upon release of restricted stock units (in shares)		33,750
Issuance of common stock upon release of restricted stock units	1,549		1,549
Stock-based compensation expense	0
Unrealized loss on available-for-sale debt securities, net	3			3
Net (loss) income	29,248				29,248
Balance, end of period (in shares) at Mar. 31, 2021		33,951,314
Balance, end of period at Mar. 31, 2021	126,190	$ 34	403,413	(5)	(277,252)
Balance, beginning of period (in shares) at Dec. 31, 2020		33,878,486
Balance, beginning of period at Dec. 31, 2020	95,035	$ 34	401,509	(8)	(306,500)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock to lender	0
Unrealized loss on available-for-sale debt securities, net	2
Net (loss) income	10,074
Balance, end of period (in shares) at Jun. 30, 2021		33,951,314
Balance, end of period at Jun. 30, 2021	109,125	$ 34	405,523	(6)	(296,426)
Balance, beginning of period (in shares) at Mar. 31, 2021		33,951,314
Balance, beginning of period at Mar. 31, 2021	126,190	$ 34	403,413	(5)	(277,252)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		0
Issuance of common stock	52		52
Stock-based compensation expense	2,058		2,058
Unrealized loss on available-for-sale debt securities, net	(1)			(1)
Net (loss) income	(19,174)				(19,174)
Balance, end of period (in shares) at Jun. 30, 2021		33,951,314
Balance, end of period at Jun. 30, 2021	109,125	$ 34	405,523	(6)	(296,426)
Balance, beginning of period (in shares) at Dec. 31, 2021		34,568,821
Balance, beginning of period at Dec. 31, 2021	72,399	$ 35	412,930	(149)	(340,417)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		5,841,786
Issuance of common stock	45,610	$ 6	45,604
Issuance of common stock upon exercise of stock options (in shares)		15,995
Issuance of common stock upon exercise of stock options	144		144
Vesting of common stock issued under Product Development Agreement	19		19
Issuance of common stock upon ESPP purchase (in shares)		18,130
Issuance of common stock upon ESPP purchase	64		64
Issuance of common stock upon release of restricted stock units (in shares)		85,106
Issuance of common stock upon release of restricted stock units	0
Stock-based compensation expense	2,047		2,047
Unrealized loss on available-for-sale debt securities, net	(373)			(373)
Net (loss) income	(22,643)				(22,643)
Balance, end of period (in shares) at Mar. 31, 2022		40,529,838
Balance, end of period at Mar. 31, 2022	97,267	$ 41	460,808	(522)	(363,060)
Balance, beginning of period (in shares) at Dec. 31, 2021		34,568,821
Balance, beginning of period at Dec. 31, 2021	72,399	$ 35	412,930	(149)	(340,417)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock to lender	$ 5,000
Issuance of common stock upon exercise of stock options (in shares)	17,599
Unrealized loss on available-for-sale debt securities, net	$ (612)
Net (loss) income	(44,527)
Balance, end of period (in shares) at Jun. 30, 2022		43,966,783
Balance, end of period at Jun. 30, 2022	102,925	$ 44	488,586	(761)	(384,944)
Balance, beginning of period (in shares) at Mar. 31, 2022		40,529,838
Balance, beginning of period at Mar. 31, 2022	97,267	$ 41	460,808	(522)	(363,060)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		2,686,288
Issuance of common stock	20,564	$ 2	20,562
Issuance of common stock to lender (in shares)		749,053
Issuance of common stock to lender	5,000	$ 1	4,999
Issuance of common stock upon exercise of stock options (in shares)		1,604
Issuance of common stock upon exercise of stock options	9		9
Stock-based compensation expense	2,208		2,208
Unrealized loss on available-for-sale debt securities, net	(239)			(239)
Net (loss) income	(21,884)				(21,884)
Balance, end of period (in shares) at Jun. 30, 2022		43,966,783
Balance, end of period at Jun. 30, 2022	$ 102,925	$ 44	$ 488,586	$ (761)	$ (384,944)

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2022	Mar. 31, 2022
Statement of Stockholders' Equity [Abstract]
Common stock offering costs	$ 716	$ 1,288

Condensed Consolidated Statem_5

Condensed Consolidated Statements of Cash Flow (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating activities
Net (loss) income	$ (44,527)	$ 10,074
Adjustments to reconcile net loss to net cash used in operating activities:
Gain from sale of priority review voucher	0	(46,493)
Income related to asset purchase agreement	0	(281)
Depreciation and amortization	146	135
Amortization of debt securities premiums and discounts	564	357
Loss on extinguishment of debt	1,144	0
Non-cash interest expense	468	384
Amortization of operating lease right-of-use assets	268	273
Common stock issued under Product Development Agreement	19	105
Stock-based compensation	4,255	3,607
Change in operating assets and liabilities:
Accounts receivable	1,538	(1,438)
Inventories	(330)	(1,972)
Prepaid expenses and other current assets	(2,636)	957
Other assets	(568)	(182)
Accounts payable	1,899	(95)
Accrued liabilities	(2,138)	(453)
Operating lease liabilities	(305)	(295)
Net cash used in operating activities	(40,203)	(35,317)
Investing activities
Purchase of debt securities available-for-sale	(45,779)	(50,066)
Proceeds from maturities of debt securities available-for-sale	23,239	74,950
Proceeds related to asset purchase agreement	0	281
Proceeds from sale of priority review voucher	0	95,000
Payments related to priority review voucher	0	(48,507)
Purchase of property and equipment	(9)	(92)
Net cash (used in) provided by investing activities	(22,549)	71,566
Financing activities
Issuance of common stock upon offering at-the-market, net of commissions	66,402	0
Proceeds from issuance of common stock to lender	5,000	0
Proceeds from debt	39,840	0
Repayment of debt	(33,277)	0
Proceeds from issuance of common stock upon stock option exercises	153	166
Proceeds from issuance of common stock upon ESPP purchase	64	136
Payment of debt issuance costs	(835)	(175)
Common stock offering costs	(244)	(184)
Net cash provided by (used in) financing activities	77,103	(57)
Net increase in cash and cash equivalents	14,351	36,192
Cash and cash equivalents at beginning of period	22,221	28,864
Cash and cash equivalents at end of period	36,572	65,056
Supplemental disclosure of cash flow information:
Interest paid	1,395	1,380
Income taxes paid	$ 152	$ 0

Description of Business

Description of Business	6 Months Ended
	Jun. 30, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business Eiger BioPharmaceuticals, Inc. (the Company or Eiger) was incorporated in the State of Delaware on November 6, 2008. Eiger is a commercial-stage biopharmaceutical company focused on the development of innovative therapies to treat and cure hepatitis delta virus (HDV), the most severe form of viral hepatitis, and other serious diseases. All five of the Company’s rare disease programs have been granted Breakthrough Therapy Designation by the U.S. Food and Drug Administration (FDA). The Eiger HDV platform includes two first-in-class therapies in Phase 3 that target critical host processes involved in viral replication. Lonafarnib is a first-in-class, oral farnesylation inhibitor and peginterferon lambda is a first-in-class, type III, interferon. Both lonafarnib and peginterferon lambda are in global Phase 3 trials. Eiger is also developing peginterferon lambda as a potential therapeutic for COVID-19. The FDA approved the Company’s first commercial product, Zokinvy (lonafarnib), to reduce risk of mortality of Hutchinson-Gilford progeria syndrome (HGPS) and for treatment of processing-deficient progeroid laminopathies (PL), collectively known as progeria, with either heterozygous LMNA mutation with progerin-like protein accumulation, or homozygous or compound heterozygous ZMPSTE24 mutations, on November 20, 2020. The Company announced that the European Commission approved its Marketing Authorization Application (MAA) for Zokinvy, under exceptional circumstances procedure on July 20, 2022. The Company is also developing avexitide, a well-characterized peptide, as a treatment for congenital hyperinsulinism (HI), an ultra-rare pediatric metabolic disorder, and post-bariatric hypoglycemia (PBH), a debilitating and potentially life-threatening condition. There are currently no approved therapies for these disorders. The Company’s principal operations are based in Palo Alto, California, with a subsidiary in Ireland. The Company operates in one segment. Liquidity As of June 30, 2022, the Company had $141.8 million of cash, cash equivalents and short-term securities, comprised of $36.6 million of cash and cash equivalents and $105.2 million of short-term debt securities available-for-sale. The Company had an accumulated deficit of $384.9 million and negative cash flows from operating activities as of June 30, 2022. As the Company continues to incur losses, its transition to profitability will depend on the successful development, approval, and commercialization of product candidates and on the achievement of sufficient revenues to support its cost structure. The Company may never achieve profitability, and until it does, the Company will need to continue to raise additional capital. Management believes that the currently available resources will be sufficient to fund its planned operations for at least the next 12 months following the issuance date of these condensed consolidated financial statements. However, if the Company’s anticipated operating results are not achieved in future periods, the Company believes that planned expenditures may need to be reduced or it would be required to raise funding in order to fund the operations. Additionally, the Company’s ability to raise additional capital may be adversely impacted by potential worsening global economic conditions and disruptions to, and volatility in, the credit and financial markets in the United States and worldwide resulting from the ongoing COVID-19 pandemic.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The unaudited condensed consolidated financial statements include the accounts of Eiger BioPharmaceuticals, Inc. and its wholly owned subsidiaries, EBPI Merger Inc., EB Pharma LLC, Eiger BioPharmaceuticals Europe Limited, and EigerBio Europe Limited, have been prepared in accordance with accounting principles generally accepted in the United States of America, (U.S. GAAP) and follow the requirements of the Securities and Exchange Commission (SEC) for annual reporting. All intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates. The Company bases its estimates on historical experience and on various other market-specific and relevant assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates. Debt Securities Short-term securities consist of debt securities classified as available-for-sale and have maturities greater than 90 days, but less than 365 days from the date of acquisition. Long-term securities consist of debt securities classified as available-for-sale and have maturities greater than 365 days from the date of acquisition. The Company’s debt securities consist of available-for-sale securities that are classified as Level 2 because their value is based on valuations using significant inputs derived from, or corroborated by, observable market data. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported as a component of accumulated other comprehensive (loss) income. The cost of available-for-sale securities sold is based on the specific-identification method . Realized gains and losses on the sale of debt securities are determined using the specific-identification method and recorded in other (expense) income, net on the accompanying unaudited condensed consolidated statements of operations. Accounts Receivable Accounts receivable represent amounts billed to the Company’s customers, net of an allowance for doubtful accounts. Trade accounts receivable are recorded at invoiced amounts and do not bear interest. The expectation of collectability is based on a review of credit profiles of customers, contractual terms and conditions, current economic trends, and historical payment experience. The Company regularly reviews the adequacy of the allowance for doubtful accounts by considering the age of each outstanding invoice and the collection history of each customer to determine the appropriate amount of allowance for doubtful accounts. The Company had no allowance as of June 30, 2022 and December 31, 2021. The Company had no bad debt expense for the three and six months ended June 30, 2022 and 2021. Inventories Inventories are stated at the lower of cost, determined based on actual costs, or estimated net realizable value, on a first-in, first-out basis. Inventories consist of raw materials, work-in-process, and finished goods. Prior to regulatory approval of the Company’s product candidates, expenses incurred to manufacture drug products are recorded as research and development expense. The Company begins capitalizing these expenses as inventory upon regulatory approval. The Company periodically assesses the recoverability of its inventory and reduces the carrying value of the inventory when items are determined to be obsolete, defective or in excess of forecasted sales requirements. Inventory write-downs for excess, defective, and obsolete inventory are recorded as a cost of sales. There have been no write-downs of inventories for the periods presented. Revenue Recognition The Company recognizes revenue upon transfer of control of promised products to customers in an amount that reflects the consideration it expects to receive in exchange for those products. To determine revenue recognition for contracts with customers, the Company performs the following five-step approach: (i) identify the contract, or contracts, with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when, or as, the performance obligation is satisfied. The five-step model is only applied to contracts when it is probable that the Company will collect substantially all of the consideration it is entitled to in exchange for the goods transferred to a customer. Product Revenue The Company’s product revenue consists of sales of Zokinvy, which received FDA approval in November 2020 and was launched commercially in the United States in January 2021. Prior to 2021, the Company had no product revenue. In the United States, the Company sells Zokinvy to a single specialty pharmacy provider that subsequently dispenses the product directly to patients. The Company discloses revenue on a total basis without further disaggregation. Additionally, the Company does not have any contract assets or liabilities, other than accounts receivable, related to its product revenue. In June 2021, the French National Agency for Medicines and Health Products Safety (ANSM) granted Zokinvy (lonafarnib) a Temporary Authorizations for Use (Autorisation Temporaire d'Utilisation or ATU) for an early access program for a term of one year. The Company has received an extension of the ATU program and expects the program to continue until commercial reimbursement of Zokinvy is approved in France. In the context of this program, the Company sells product to a distributor who in turn ships product to pharmacies after receiving requests from physicians for patients in France. In November 2021, the Company began distributing and recognizing revenue from sales of Zokinvy (lonafarnib) through a reimbursed early access program in France. There was no revenue from sale of product under the ATU program for the six months ended June 30, 2022. The Company recognizes product revenue when a customer obtains control of its product, which occurs at a point in time, typically upon delivery to a customer as the delivery of the product is the Company’s only performance obligation. Shipping and handling activities are fulfillment activities rather than a separate performance obligation and are recorded in cost of sales. Product revenue is recorded at the net sales price (transaction price), which includes estimates of variable consideration resulting from rebates, prompt payment discounts, co-payment assistance, and returns. Amounts related to such items are estimated at contract inception and updated at the end of each reporting period as additional information becomes available. The amount of variable consideration may be constrained and is included in the transaction price only to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Product revenue is recorded after considering the impact of the following variable consideration amounts along with the constraint at the time of revenue recognition: Rebates: The Company’s product is subject to government mandated rebates for Medicaid Drug Rebate Program, Medicare Part D Prescription Drug Benefit Program, and other government health care programs in the United States. Rebate amounts are based upon contractual agreements or legal requirements with public sector benefit providers. The Company uses the expected-value method for estimating these rebates based on statutory discount rates and expected utilization. The expected utilization of rebates is estimated based on expected coverage of identified patients. Estimates for these rebates are adjusted quarterly to reflect the most recent information. The Company records an accrued liability for unpaid rebates related to products for which control has been transferred to a customer. Prompt payment discounts: The Company provides a discount to a customer if it pays for purchases within 30 days. The Company expects that its customers will earn prompt payment discounts and uses the most likely amount method for estimating such discounts. As a result, when revenues are recognized, the Company deducts the full amount of the prompt payment discounts from total product revenues and records these discounts as a reduction of accounts receivable. Co-payment assistance: The Company provides co-payment assistance to patients who have commercial insurance and meet certain eligibility requirements. The Company uses the expected-value method for estimating co-payment assistance based on estimates of program redemption using data provided by third-party administrators. Estimates for the co-payment assistance are adjusted quarterly to reflect actual experience. The Company records an accrued liability for unredeemed co-payment assistance related to products for which control has been transferred to a customer. Product returns: The Company offers limited product return rights and generally allows for the return of product that is damaged or defective, or within a few months prior to and up to a few months after the product expiration date. The Company considers several factors in the estimation of potential product returns, including expiration dates of the product shipped, the limited product return rights, third-party data in monitoring channel inventory levels, shelf life of the product, and other relevant factors. Other Revenue The Company’s other revenue consists of milestone payments from the Marketing and Distribution Agreement (MDA) with AnGes, Inc., which was executed in May 2022. The agreement provides AnGes with a right to use the Company's intellectual property (IP) and seek regulatory approval for and commercialization of Zokinvy in Japan. The Company will receive additional payments upon achievement of certain regulatory milestones. Cost of Sales Cost of sales consists primarily of direct and indirect costs related to the manufacturing of Zokinvy for commercial sale, including third-party manufacturing costs, packaging services, freight, storage costs, and write down of inventories. Accrued Research and Development Costs The Company accrues for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of preclinical and clinical studies, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and includes these costs in accrued liabilities in the accompanying unaudited condensed consolidated balance sheets and within research and development expenses in the accompanying unaudited condensed consolidated statements of operations. The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with its third-party service providers. The Company makes judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities. Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326) . The standard changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. Financial assets measured at amortized cost will be presented at the net amount expected to be collected by using an allowance for credit losses. In April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, which clarifies and corrects certain unintended applications of the guidance contained in each of the amended Topics. Additionally, in May 2019, the FASB issued ASU No. 2019-05, Financial Instruments – Credit Losses (Topic 326), which provides an option to irrevocably elect to measure certain individual financial assets at fair value instead of amortized cost. In November 2019, the FASB issued ASU No. 2019-10, Financial Instruments – Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842) , which defers the effective date for ASU No. 2016-13 for smaller reporting companies to fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The Company is evaluating the impact of the guidance on its unaudited condensed consolidated financial statements. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) . The standard provides optional expedients for facilitating the effects of the reference rate reform on financial reporting. For the Company, there are two applicable optional expedients for contract modifications permitted for contracts that are modified because of the reference rate reform and meet the scope guidance. The modifications of contracts within the scope of ASC Topic 470 should be accounted for prospectively adjusting the effective interest rate. The modifications of contracts within the scope of ASC Topic 842 should be accounted for as a continuation of the existing contracts with no reassessments of the lease classification and the discount rate or remeasurements of lease payments that otherwise would be required under ASC Topic 842 for modifications not accounted for as separate contracts. The pronouncement is effective for all entities as of March 12, 2020 through December 31, 2022. In October 2021, the Company amended its Oxford Loan to replace its floating interest rate with the LIBOR replacement rate (see Note 7). The Company adopted this standard when LIBOR was about to be discontinued and the adoption did not have a material impact on its unaudited condensed consolidated financial statements.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value MeasurementsFair value accounting is applied for all financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis (at least annually). As of June 30, 2022 and December 31, 2021, the carrying amount of accounts receivable, prepaid expenses and other current assets, accounts payable and accrued liabilities approximated their estimated fair value due to their relatively short maturities. Management believes the terms of its long-term debt reflect current market conditions for an instrument with similar terms and maturity, therefore the carrying value of the Company’s debt approximated its fair value. Assets and liabilities recorded at fair value on a recurring basis in the unaudited condensed consolidated balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1 : Inputs are unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2 : Inputs are observable, unadjusted quoted prices in active markets for similar assets or liabilities, unadjusted quoted prices for identical or similar assets or liabilities 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 related assets or liabilities; and Level 3 : Unobservable inputs that are significant to the measurement of the fair value of the assets or liabilities that are supported by little or no market data. The Company’s money market funds are classified as Level 1 because they are valued using quoted market prices. The Company’s debt securities consist of available-for-sale securities and are classified as Level 2 because their value is based on valuations using significant inputs derived from or corroborated by observable market data. There were no assets or liabilities classified as Level 3 as of June 30, 2022 and December 31, 2021. There were no transfers into or out of Level 3 of the fair value hierarchy during the periods presented. The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): June 30, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 22,101 $ — $ — $ 22,101 Corporate debt securities — 38,527 — 38,527 Commercial paper — 10,942 — 10,942 U.S. government bonds — 55,751 — 55,751 Total $ 22,101 $ 105,220 $ — $ 127,321 December 31, 2021 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 13,520 $ — $ — $ 13,520 Corporate debt securities — 41,511 — 41,511 U.S. government bonds — 42,345 — 42,345 Total $ 13,520 $ 83,856 $ — $ 97,376 There were no financial liabilities as of June 30, 2022 and December 31, 2021. The following tables summarize the estimated value of the Company’s cash equivalents and debt securities and the gross unrealized holding gains and losses (in thousands): June 30, 2022 Amortized cost Unrealized gain Unrealized loss Estimated Fair Cash equivalents: Money market funds $ 22,101 $ — $ — $ 22,101 Total cash equivalents $ 22,101 $ — $ — $ 22,101 Debt securities: Corporate debt securities $ 38,829 $ — $ (302) $ 38,527 Commercial paper 10,942 — — 10,942 U.S. government bonds 56,210 — (459) 55,751 Total debt securities $ 105,981 $ — $ (761) $ 105,220 Classified as: Cash equivalents $ 22,101 Short-term debt securities 105,220 $ 127,321 December 31, 2021 Amortized cost Unrealized gain Unrealized loss Estimated Fair Cash equivalents: Money market funds $ 13,520 $ — $ — $ 13,520 Total cash equivalents $ 13,520 $ — $ — $ 13,520 Debt securities: Corporate debt securities $ 41,576 $ — $ (65) $ 41,511 U.S. government bonds 42,429 — (84) 42,345 Total debt securities $ 84,005 $ — $ (149) $ 83,856 Classified as: Cash equivalents $ 13,520 Short-term debt securities 66,594 Long-term debt securities 17,262 $ 97,376 The Company periodically reviews the available-for-sale securities for other-than-temporary impairment loss. The Company considers factors such as the duration, severity and the reason for the decline in value, the potential recovery period and its intent to sell. For debt securities, it also considers whether (i) it is more likely than n ot that the Company will be required to sell the debt securities before recovery of their amortized cost basis, and (ii) the amortized cost basis cannot be recovered as a result of credit losses. During the six months ended June 30, 2022, the Company did not recognize any other-than-temporary impairment losses. All debt securities with unrealized losses have been in a loss position for less than 12 months.

Balance Sheet Components

Balance Sheet Components	6 Months Ended
	Jun. 30, 2022
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	Balance Sheet Components Inventories Inventories consist of the following (in thousands): June 30, December 31, Raw materials $ 1,056 $ 1,056 Work-in-progress 1,747 1,468 Finished goods 73 88 Total inventories $ 2,876 $ 2,612 Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consist of the following (in thousands): June 30, December 31, Prepaid contract manufacturing costs $ 4,694 $ 3,695 Prepaid research costs 3,463 3,253 Prepaid insurance 1,295 631 Prepaid marketing 783 469 Other 1,762 1,313 Total prepaid expenses and other current assets $ 11,997 $ 9,361 Accrued Liabilities Accrued liabilities consist of the following (in thousands): June 30, December 31, Contract research costs $ 4,101 $ 4,760 Compensation and related benefits 2,404 3,131 Contract manufacturing costs 1,955 3,288 Product revenue reserves 1,789 1,846 Other 1,217 674 Total accrued liabilities $ 11,466 $ 13,699

Bristol-Meyers Squibb License A

Bristol-Meyers Squibb License Agreement	6 Months Ended
	Jun. 30, 2022
Product Development Agreement [Abstract]
Product Development Agreement	Bristol-Meyers Squibb License Agreement On April 20, 2016, the Company and Bristol-Myers Squibb Company (BMS) entered into a License Agreement (the BMS License Agreement) and a Common Stock Purchase Agreement (the BMS Purchase Agreement). Under the BMS License Agreement, BMS granted the Company an exclusive, worldwide, license to research, develop, manufacture, and sell products containing PEG-interferon Lambda-1a (perinterferon lambda or the Licensed Product) for all therapeutic and diagnostic uses in humans and animals. The Company is responsible for the development and commercialization of the Licensed Product at its sole cost and expense. The Company paid BMS $2.0 million and issued 157,587 shares of its common stock at an aggregate fair value of $3.2 million in April 2016. The BMS License Agreement also includes development and regulatory milestone payments totaling $61.0 million and commercial sales milestones of up to $128.0 million. The Company is obligated to pay BMS annual net sales royalties in the range of mid-single to mid-teens, depending on net sales levels. In fourth quarter of 2020, the Company recorded in research and development expense a $3.0 million milestone, triggered on successful demonstration of proof of concept, as defined by the BMS License Agreement, in a Phase 2 clinical trial. In March 2022, the Company recorded a $5.0 million milestone expense in research

Asset Purchase Agreements

Asset Purchase Agreements	6 Months Ended
	Jun. 30, 2022
Asset Purchase Agreements And Related License Agreements [Abstract]
Asset Purchase Agreements and Related License Agreements	Asset Purchase Agreement On November 20, 2020, Eiger entered into an asset purchase agreement (the APA) with AbbVie, Inc. (AbbVie) to sell its rare pediatric disease priority review voucher (the PRV), which was awarded on November 20, 2020 upon FDA approval of Zokinvy. The APA contains customary representations, warranties, covenants, and indemnification provisions subject to certain limitations. In consideration for the PRV, AbbVie agreed to pay the Company $95.0 million. The transaction closed in January 2021. Such consideration was shared with the Progeria Research Foundation (PRF) in accordance with the terms of the PRF Collaboration and Supply Agreement, pursuant to which the Company and PRF will equally share any net proceeds from the sale of a priority review voucher that the Company may receive as the sponsor of a rare pediatric disease product application. The Company retained $46.5 million of proceeds from the sale of the PRV, net of related payments, and recorded the amount in other (expense) income, net in the unaudited condensed consolidated statement of operations for the six months ended June 30, 2021.

Debt

Debt	6 Months Ended
	Jun. 30, 2022
Debt Disclosure [Abstract]
Debt	Debt Innovatus Term Loan On June 1, 2022 (Closing Date), the Company entered into a term loan and security agreement (Innovatus Loan) with Innovatus Life Sciences Lending Fund I, LP (Innovatus), providing for up to $75.0 million funded in three tranches with a maturity date of August 31, 2027. The floating per annum interest rate of the Innovatus Loan is equal to the sum of (a) the greater of (i) the Prime Rate published in the Money Rates section of the Wall Street Journal (or any successor thereto) and (ii) 3.5%, plus (b) 3.75%; provided that, at the election of the Borrower, up to 2.25% of such rate shall be payable in-kind until the third anniversary of the closing date. The Company is required to make monthly interest-only payments through July 1, 2027, after which the Company is required to make monthly amortizing payments, with the remaining balance of the principal plus accrued and unpaid interest due at maturity. 2.25% of the interest is payable in-kind for the first three years of the term by increasing the principal balance. Prepayments of the loan, in whole or in part, will be subject to an early prepayment fee which declines each year until the third anniversary date of the Closing Date, after which no prepayment fee is required. The Company is also required to pay an exit fee upon any payment or prepayment equal to 6.5% of the aggregate principal amount of the tranches funded under the Innovatus Loan. The Innovatus Loan contains customary representations, warranties, events of default and covenants of the Company and its subsidiaries, including a requirement to maintain a cash balance of not less than 5% of the aggregate principal amount of funded and outstanding loan terms at all times. The Innovatus Loan is secured by perfected first priority liens on the Company's assets, including a commitment by the Company to not allow any liens to be placed upon the Company's intellectual property. The Company was funded $40.0 million in June 2022 on the Closing Date under Tranche A. The remaining $35.0 million is divided into two tranches (Tranche B and Tranche C). The $17.5 million under each of Tranche B and Tranche C will be available for a period commencing on the later of (a) the first date that the Company achieves certain development and regulatory milestones applicable to each Tranche and (b) November 1, 2022. Both Tranche B and Tranche C draw periods end on the earlier of (a) June 30, 2024 or (b) an event of default. The Company identified a number of embedded derivatives that require bifurcation from the Innovatus Loan. These embedded features include mandatory prepayment upon an event of default or change in control and contingent rate increases. However, the fair value of these embedded features was deemed to be immaterial on the date of issuance. At each subsequent reporting period, the Company will reassess the fair value of the embedded features and will record a liability if the fair value of the features becomes material. In connection with the issuance of the Innovatus Loan, the Company recorded a debt discount of $0.2 million and capitalized debt issuance costs of $1.0 million. The discount and issuance costs will be amortized over the life of the loan. Interest expense for the three and six months ended June 30, 2022 was $0.3 million and $0.3 million, respectively, and is inclusive of non-cash amortization of the debt discount and debt issuance costs and accretion of final payment. The carrying value of the Innovatus Loan at June 30, 2022 was $38.9 million. The carrying amount of the Innovatus Loan approximates fair value given its recent issuance. The effective interest rate for the Innovatus Loan was 10.13% as of June 30, 2022. Additionally, in connection with entering into the Innovatus Loan, the Company entered into a Stock Purchase Agreement with Innovatus for the sale of common stock with an aggregate value of $5.0 million. On June 3, 2022, the Company issued 749,053 shares of common stock to Innovatus at a per share purchase price of $6.6751, the preceding five-day volume weighted average price per share. A portion of the loan proceeds were used to repay in full the approximately $33.5 million of aggregate principal amount, unpaid interest, and exit fees in connection with loans outstanding owed to Oxford Finance LLC by the Company. Oxford Term Loan In December 2016, the Company entered into an aggregate $25.0 million loan with Oxford Finance LLC (the Oxford Loan) with a maturity date of July 1, 2021. The Company borrowed $15.0 million in December 2016 (Tranche A). In May 2018, the Company entered into an amendment to the Oxford Loan and borrowed $5.0 million (Tranche B). On August 3, 2018, the Company borrowed the remaining $5.0 million (Tranche C) under the Oxford Loan. On March 5, 2019, the Company entered into the third amendment to the Oxford Loan (the Amended Oxford Loan) to refinance the Oxford Loan. The Amended Oxford Loan increased the aggregate amount available to be borrowed to $35.0 million and extended the maturity date to March 1, 2024. On March 5, 2019, prior to entering into the Amended Oxford Loan, the outstanding balance of the Oxford Loan was $23.3 million. At the time of entering into the Amended Oxford Loan, the Company borrowed an additional $6.7 million in principal under the Amended Oxford Loan, which increased the total amount borrowed to $30.0 million (Amended Tranche A). The remaining $5.0 million (Amended Tranche B) was available to the Company provided that certain milestones are achieved by February 2021. The Company did not draw down the Amended Tranche B. On February 23, 2021, the Company entered into the fifth amendment to the Oxford Loan. The amendment extended the interest only period by 17 months until September 1, 2022, followed by 19 equal monthly payments of principal and interest. The Company paid an amendment fee of $0.2 million to the lender on the effective date of the fifth amendment, which was recorded as an additional debt discount and was being amortized over the remaining term of the Amended Oxford Loan. On October 6, 2021, the Company entered into the sixth amendment to the Oxford Loan, which amended the interest to be the LIBOR replacement rate which is the sum of the alternate benchmark rate and the LIBOR replacement spread. At the time of final payment, the Company was required to pay an exit fee of 7.50% of the original principal balance of borrowed funds, or $2.3 million. In addition, the Company was required to pay an additional exit fee of $1.0 million. The Company recorded as a liability and debt discount the exit fee for the Amended Oxford Loan. At the date of the Amended Oxford Loan, the Company paid $0.9 million for the accrued portion of the Oxford Loan exit fee and the Tranche B additional exit fee. On June 1, 2022, upon entering into the Innovatus Loan, the Company repaid the Oxford Loan, including (i) the $30.0 million outstanding principal balances, (ii) $0.2 million in accrued and unpaid interest, and (iii) other final payments consisting of $3.3 million, for a total payment of $33.5 million. The Company recorded a loss of $1.1 million on early extinguishment of the debt related to the unamortized debt premium, discount, and cost of issuance, which was recognized as a component of other (expense) income, net in the condensed consolidated statement of operations and other comprehensive loss. The Company accounts for the amortization of the debt discount utilizing the effective interest method. Debt and unamortized discount balances are as follows (in thousands): June 30, December 31, Face value of debt $ 40,074 $ 30,000 Exit fee 2,600 3,277 Unamortized debt discount associated with exit fee, debt issuance costs and loan origination fees (3,758) (1,482) Total debt, net 38,916 31,795 Less: current portion of debt — (7,809) Debt, net $ 38,916 $ 23,986

Stock-Based Compensation

Stock-Based Compensation	6 Months Ended
	Jun. 30, 2022
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation	Stock-Based Compensation During the second quarter of 2021, the Company approved the 2021 Inducement Plan to reserve 850,000 shares of its common stock to be used exclusively for grants of awards to individuals that were not previously employees or directors of the Company as a material inducement to such individuals’ entry into employment with the Company within the meaning of Rule 5635(c)(4) of the Nasdaq Listing Rules. As of June 30, 2022, there were 380,000 shares remaining available to be issued under the 2021 Inducement Plan. The following table summarizes stock option activity under the Company’s stock-based compensation plans during the six months ended June 30, 2022 (in thousands, except option and share data): Shares Number of Weighted- Weighted- Aggregate Outstanding as of December 31, 2021 1,327,645 5,262,185 $ 10.24 7.25 $ 530 Additional options authorized 1,728,441 — Granted (1,835,700) 1,835,700 $ 5.59 Restricted stock units granted (298,150) — Performance stock units granted (30,000) — Exercised — (17,599) $ 8.67 Forfeited 188,277 (188,277) $ 10.90 Restricted stock units forfeited 48,025 — Outstanding as of June 30, 2022 1,128,538 6,892,009 $ 8.99 7.67 $ 2,758 Vested and exercisable as of June 30, 2022 3,409,980 $ 10.79 6.23 $ 1,017 During the three and six months ended June 30, 2022, the weighted-average grant date fair value of options granted were $4.39 and $3.53 per share, respectively. During the three and six months ended June 30, 2021, the weighted-average grant date fair value of options granted were $6.07 and $7.36 per share, respectively. The Company records stock-based compensation of stock options granted by estimating the fair value of stock-based awards using the Black-Scholes option pricing model and amortizes the fair value of the stock-based awards granted over the applicable vesting period of the awards on a straight-line basis. The fair value of stock options was estimated using the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2022 2021 2022 2021 Expected term (in years) 6.08-6.08 6.02-6.08 5.27-6.08 5.27-6.08 Volatility 70.15%-71.20% 73.18%-99.72% 68.71%-71.20% 72.39%-100.87% Risk free interest rate 2.84%-3.03% 1.02%-1.09% 1.76%-3.03% 0.62%-1.16% Dividend yield — — — — Restricted Stock Units and Performance Stock Units In the first quarter of 2020, the Company revised its non-employee director compensation policy to approve the granting of restricted stock units (RSUs) in accordance with the Restated 2013 Equity Incentive Plan (the Restated 2013 Plan). Each eligible director who has served for at least six months during the prior calendar year and continues to serve as a non-employee member of the board of Directors (the Board) is granted RSUs. Each eligible director who has served on the Board for less than six months during the prior calendar year and who continues to serve as a non-employee member of the Board, is granted RSUs which are pro-rated for the period served during the prior calendar year. The RSUs granted to non-employee directors will vest on the one-year anniversary of the grant date, subject to the eligible director’s continuous services through the vesting date, and will vest in full upon a change in control, as defined under the Restated 2013 Plan. The RSUs granted to employees will vest annually on the one-year, two-year, and three-year anniversaries of the grant date. The fair value of all RSUs is measured at the grant date based on the closing market price of the Company’s common stock and is recognized as stock-based compensation expense on a straight-line basis over the vesting period. The performance stock units (PSUs) are also available for grant pursuant to the Restated 2013 Plan. Each PSU, which is a stock award, is earned through the achievement of performance-based metrics over a defined performance period. The length of the defined performance period, the performance-based metric to be achieved during the defined performance period, and the measure of whether and to what degree such performance-based metric has been achieved will be conclusively determined by the compensation committee of the Company’s Board, in its sole discretion. The estimated fair value of equity awards that contain performance conditions is expensed over the term of the award once the Company has determined that it is probable that performance conditions will be satisfied. There were no PSUs granted during the three and the six months ended June 30, 2021. During the three and six months ended June 30, 2022, the Company granted 30,000 PSUs with a weighted-average grant date fair value of $6.87 per share for both periods. As of June 30, 2022, no PSUs have vested as the performance-based metrics of the PSUs have not yet been achieved. There were no RSUs granted during the three months ended June 30, 2022 and 2021. During the six months ended June 30, 2022, the Company granted 298,150 RSUs with a weighted-average grant date fair value of $5.22 per share. During the six months ended June 30, 2021, the Company granted 203,500 RSUs with a weighted-average grant date fair value of $9.99 per share. In relation to the RSUs granted, the Company recognized $0.5 million and $0.2 million in stock-based compensation expense for the three months ended June 30, 2022 and 2021, respectively, and $0.9 million and $0.3 million in stock-based compensation expense for the six months ended June 30, 2022 and 2021, respectively, which were included in selling, general and administrative expenses. As of June 30, 2022, the total unrecognized compensation expense related to unvested RSUs and PSUs was $4.7 million, which the Company expects to recognize over an estimated weighted-average period of 2.5 years. The following table summarizes RSU and PSU activity and weighted average grant date fair value for the six months ended June 30, 2022: Shares Weighted- Unvested shares as of December 31, 2021 623,000 $ 8.63 Granted 328,150 $ 5.37 Vested (85,106) $ 10.09 Forfeited (48,025) $ 7.89 Unvested shares as of June 30, 2022 818,019 $ 7.21 Stock-Based Compensation Expense Total stock-based compensation expense recognized was as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2022 2021 2022 2021 Research and development $ 820 $ 551 $ 1,445 $ 942 Selling, general and administrative 1,388 1,507 2,810 2,665 Total $ 2,208 $ 2,058 $ 4,255 $ 3,607 As of June 30, 2022, the total unrecognized compensation expense related to unvested options was $15.4 million, which the Company expects to recognize over an estimated weighted average period of 2.9 years.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2022
Income Tax Disclosure [Abstract]
Income Taxes	Income TaxesThe Company’s provision for income taxes was approximately $17,000 and $26,000 for the three and six months ended June 30, 2022, respectively, with an effective tax rate of (0.06)% for the six months ended June 30, 2022. The Company's provision for income taxes was approximately $11,000 and $30,000 for the three and six months ended June 30, 2021, with an effective tax rate of 0.2% for the six months ended June 30, 2021. The effective tax rate in each period differs from the U.S. statutory tax rate primarily due to the valuation allowances on the Company’s deferred tax assets as it is more likely than not that some or all of the Company’s deferred tax assets will not be realized. The tax expense recorded for the three and six months ended June 30, 2022 relates to state taxes.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2022
Leases [Abstract]
Commitments and Contingencies	Commitments and Contingencies Lease Agreements In October 2017, the Company entered into a non-cancelable operating facility lease agreement for 8,029 square feet of office space located at 2155 Park Blvd. in Palo Alto, California. The lease commenced on March 1, 2018 and expires in February 2023. The lease has a three-year renewal option prior to expiration; however, the Company is not reasonably assured to exercise this option. The lease includes rent escalation clauses throughout the lease term. In October 2017, the Company provided a security deposit of $0.3 million. The Company also has additional operating leases that are included in its lease accounting but are not considered significant for disclosure. The maturities of the Company’s operating lease liabilities as of June 30, 2022 were as follows (in thousands): Undiscounted lease payments June 30, 2022 Remaining in 2022 $ 334 2023 115 2024 1 2025 1 Total undiscounted payments 451 Less: imputed interest 12 Present value of future lease payments 439 Less: current portion of operating lease liabilities 436 Operating lease liabilities $ 3 Rent expense recognized for the Company’s operating leases was $0.1 million and $0.1 million for the three months ended June 30, 2022 and 2021, respectively, and $0.3 million and $0.3 million for the six months ended June 30, 2022 and 2021, respectively. Under the terms of the lease agreements, the Company is also responsible for certain variable lease payments that are not included in the measurement of the lease liability. Variable lease payments for the operating leases were $23,000 and $23,000 for the three months ended June 30, 2022 and 2021, respectively; and $46,000 and $46,000 for the six months ended June 30, 2022 and 2021, respectively.

Net (Loss) Income Per Share

Net (Loss) Income Per Share	6 Months Ended
	Jun. 30, 2022
Earnings Per Share [Abstract]
Net (Loss) Income Per Share	Net (Loss) Income Per Share Basic net (loss) income per share of common stock is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration for potentially dilutive securities. Since the Company was in a loss position for the three and six months ended June 30, 2022, and three months ended June 30, 2021, diluted net loss per share is the same as basic net loss per share as the inclusion of all potential common shares outstanding would have been anti-dilutive. Diluted net income per share for the six months ended June 30, 2021 is computed by dividing net income by the weighted-average number of shares of common stock and dilutive potential common stock equivalents then outstanding. Dilutive potential common stock equivalents include the assumed exercise, vesting and issuance of employee stock awards using the treasury stock method. The following table sets forth the computation of basic and diluted net (loss) income per common share for the periods presented (in thousands, except share amounts): Three Months Ended Six Months Ended 2022 2021 2022 2021 Numerator: Net (loss) income $ (21,884) $ (19,174) $ (44,527) $ 10,074 Denominator: Weighted-average shares outstanding for basic net (loss) income per share 43,059,809 33,932,127 39,178,043 33,909,637 Effect of dilutive securities — — — 247,240 Weighted-average shares outstanding for diluted net (loss) income per share 43,059,809 33,932,127 39,178,043 34,156,877 Net (loss) income per share: Basic $ (0.51) $ (0.57) $ (1.14) $ 0.30 Diluted $ (0.51) $ (0.57) $ (1.14) $ 0.29 The following table sets forth the outstanding potentially dilutive securities which have been excluded in the calculation of diluted net (loss) income per share because including such securities would be anti-dilutive (in common stock equivalent shares): Three Months Ended Six Months Ended 2022 2021 2022 2021 Options to purchase common stock 6,892,009 5,016,630 6,892,009 3,514,249 Restricted stock units (unvested) 818,019 224,504 818,019 105,965 ESPP 89,662 56,940 89,662 6,884 Total 7,799,690 5,298,074 7,799,690 3,627,098

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The unaudited condensed consolidated financial statements include the accounts of Eiger BioPharmaceuticals, Inc. and its wholly owned subsidiaries, EBPI Merger Inc., EB Pharma LLC, Eiger BioPharmaceuticals Europe Limited, and EigerBio Europe Limited, have been prepared in accordance with accounting principles generally accepted in the United States of America, (U.S. GAAP) and follow the requirements of the Securities and Exchange Commission (SEC) for annual reporting. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of Estimates The preparation of unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. On an ongoing basis, the Company evaluates its estimates. The Company bases its estimates on historical experience and on various other market-specific and relevant assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Debt Securities	Debt Securities Short-term securities consist of debt securities classified as available-for-sale and have maturities greater than 90 days, but less than 365 days from the date of acquisition. Long-term securities consist of debt securities classified as available-for-sale and have maturities greater than 365 days from the date of acquisition. The Company’s debt securities consist of available-for-sale securities that are classified as Level 2 because their value is based on valuations using significant inputs derived from, or corroborated by, observable market data. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported as a component of accumulated other comprehensive (loss) income. The cost of available-for-sale securities sold is based on the specific-identification method . Realized gains and losses on the sale of debt securities are determined using the specific-identification method and recorded in other (expense) income, net on the accompanying unaudited condensed consolidated statements of operations.
Accounts Receivable	Accounts Receivable Accounts receivable represent amounts billed to the Company’s customers, net of an allowance for doubtful accounts. Trade accounts receivable are recorded at invoiced amounts and do not bear interest. The expectation of collectability is based on a review of credit profiles of customers, contractual terms and conditions, current economic trends, and historical payment experience. The Company regularly reviews the adequacy of the allowance for doubtful accounts by considering the age of each outstanding invoice and the collection history of each customer to determine the appropriate amount of allowance for doubtful accounts.
Inventories	Inventories Inventories are stated at the lower of cost, determined based on actual costs, or estimated net realizable value, on a first-in, first-out basis. Inventories consist of raw materials, work-in-process, and finished goods. Prior to regulatory approval of the Company’s product candidates, expenses incurred to manufacture drug products are recorded as research and development expense. The Company begins capitalizing these expenses as inventory upon regulatory approval.
Revenue Recognition	Revenue Recognition The Company recognizes revenue upon transfer of control of promised products to customers in an amount that reflects the consideration it expects to receive in exchange for those products. To determine revenue recognition for contracts with customers, the Company performs the following five-step approach: (i) identify the contract, or contracts, with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when, or as, the performance obligation is satisfied. The five-step model is only applied to contracts when it is probable that the Company will collect substantially all of the consideration it is entitled to in exchange for the goods transferred to a customer. Product Revenue The Company’s product revenue consists of sales of Zokinvy, which received FDA approval in November 2020 and was launched commercially in the United States in January 2021. Prior to 2021, the Company had no product revenue. In the United States, the Company sells Zokinvy to a single specialty pharmacy provider that subsequently dispenses the product directly to patients. The Company discloses revenue on a total basis without further disaggregation. Additionally, the Company does not have any contract assets or liabilities, other than accounts receivable, related to its product revenue. In June 2021, the French National Agency for Medicines and Health Products Safety (ANSM) granted Zokinvy (lonafarnib) a Temporary Authorizations for Use (Autorisation Temporaire d'Utilisation or ATU) for an early access program for a term of one year. The Company has received an extension of the ATU program and expects the program to continue until commercial reimbursement of Zokinvy is approved in France. In the context of this program, the Company sells product to a distributor who in turn ships product to pharmacies after receiving requests from physicians for patients in France. In November 2021, the Company began distributing and recognizing revenue from sales of Zokinvy (lonafarnib) through a reimbursed early access program in France. There was no revenue from sale of product under the ATU program for the six months ended June 30, 2022. The Company recognizes product revenue when a customer obtains control of its product, which occurs at a point in time, typically upon delivery to a customer as the delivery of the product is the Company’s only performance obligation. Shipping and handling activities are fulfillment activities rather than a separate performance obligation and are recorded in cost of sales. Product revenue is recorded at the net sales price (transaction price), which includes estimates of variable consideration resulting from rebates, prompt payment discounts, co-payment assistance, and returns. Amounts related to such items are estimated at contract inception and updated at the end of each reporting period as additional information becomes available. The amount of variable consideration may be constrained and is included in the transaction price only to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Product revenue is recorded after considering the impact of the following variable consideration amounts along with the constraint at the time of revenue recognition: Rebates: The Company’s product is subject to government mandated rebates for Medicaid Drug Rebate Program, Medicare Part D Prescription Drug Benefit Program, and other government health care programs in the United States. Rebate amounts are based upon contractual agreements or legal requirements with public sector benefit providers. The Company uses the expected-value method for estimating these rebates based on statutory discount rates and expected utilization. The expected utilization of rebates is estimated based on expected coverage of identified patients. Estimates for these rebates are adjusted quarterly to reflect the most recent information. The Company records an accrued liability for unpaid rebates related to products for which control has been transferred to a customer. Prompt payment discounts: The Company provides a discount to a customer if it pays for purchases within 30 days. The Company expects that its customers will earn prompt payment discounts and uses the most likely amount method for estimating such discounts. As a result, when revenues are recognized, the Company deducts the full amount of the prompt payment discounts from total product revenues and records these discounts as a reduction of accounts receivable. Co-payment assistance: The Company provides co-payment assistance to patients who have commercial insurance and meet certain eligibility requirements. The Company uses the expected-value method for estimating co-payment assistance based on estimates of program redemption using data provided by third-party administrators. Estimates for the co-payment assistance are adjusted quarterly to reflect actual experience. The Company records an accrued liability for unredeemed co-payment assistance related to products for which control has been transferred to a customer. Product returns: The Company offers limited product return rights and generally allows for the return of product that is damaged or defective, or within a few months prior to and up to a few months after the product expiration date. The Company considers several factors in the estimation of potential product returns, including expiration dates of the product shipped, the limited product return rights, third-party data in monitoring channel inventory levels, shelf life of the product, and other relevant factors. Other Revenue The Company’s other revenue consists of milestone payments from the Marketing and Distribution Agreement (MDA) with AnGes, Inc., which was executed in May 2022. The agreement provides AnGes with a right to use the Company's
Cost of Sales	Cost of SalesCost of sales consists primarily of direct and indirect costs related to the manufacturing of Zokinvy for commercial sale, including third-party manufacturing costs, packaging services, freight, storage costs, and write down of inventories.
Accrued Research and Development Costs	Accrued Research and Development Costs The Company accrues for estimated costs of research and development activities conducted by third-party service providers, which include the conduct of preclinical and clinical studies, and contract manufacturing activities. The Company records the estimated costs of research and development activities based upon the estimated amount of services provided but not yet invoiced and includes these costs in accrued liabilities in the accompanying unaudited condensed consolidated balance sheets and within research and development expenses in the accompanying unaudited condensed consolidated statements of operations. The Company accrues for these costs based on factors such as estimates of the work completed and in accordance with agreements established with its third-party service providers. The Company makes judgments and estimates in determining the accrued liabilities balance in each reporting period. As actual costs become known, the Company adjusts its accrued liabilities.
Accounting Pronouncements Not Yet Adopted	Accounting Pronouncements Not Yet Adopted In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326) . The standard changes how entities will measure credit losses for most financial assets and certain other instruments that are not measured at fair value through net income. Financial assets measured at amortized cost will be presented at the net amount expected to be collected by using an allowance for credit losses. In April 2019, the FASB issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments – Credit Losses, Topic 815, Derivatives and Hedging, and Topic 825, Financial Instruments, which clarifies and corrects certain unintended applications of the guidance contained in each of the amended Topics. Additionally, in May 2019, the FASB issued ASU No. 2019-05, Financial Instruments – Credit Losses (Topic 326), which provides an option to irrevocably elect to measure certain individual financial assets at fair value instead of amortized cost. In November 2019, the FASB issued ASU No. 2019-10, Financial Instruments – Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842) , which defers the effective date for ASU No. 2016-13 for smaller reporting companies to fiscal years beginning after December 15, 2022, including interim periods within those fiscal years. The Company is evaluating the impact of the guidance on its unaudited condensed consolidated financial statements. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848) . The standard provides optional expedients for facilitating the effects of the reference rate reform on financial reporting. For the Company, there are two applicable optional expedients for contract modifications permitted for contracts that are modified because of the reference rate reform and meet the scope guidance. The modifications of contracts within the scope of ASC Topic 470 should be accounted for prospectively adjusting the effective interest rate. The modifications of contracts within the scope of ASC Topic 842 should be accounted for as a continuation of the existing contracts with no reassessments of the lease classification and the discount rate or remeasurements of lease payments that otherwise would be required under ASC Topic 842 for modifications not accounted for as separate contracts. The pronouncement is effective for all entities as of March 12, 2020 through December 31, 2022. In October 2021, the Company amended its Oxford Loan to replace its floating interest rate with the LIBOR replacement rate (see Note 7). The Company adopted this standard when LIBOR was about to be discontinued and the adoption did not have a material impact on its unaudited condensed consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2022
Fair Value Disclosures [Abstract]
Summary of Assets and Liabilities Measured at Fair Value	The following tables present the fair value hierarchy for assets and liabilities measured at fair value (in thousands): June 30, 2022 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 22,101 $ — $ — $ 22,101 Corporate debt securities — 38,527 — 38,527 Commercial paper — 10,942 — 10,942 U.S. government bonds — 55,751 — 55,751 Total $ 22,101 $ 105,220 $ — $ 127,321 December 31, 2021 Level 1 Level 2 Level 3 Total Financial assets: Money market funds $ 13,520 $ — $ — $ 13,520 Corporate debt securities — 41,511 — 41,511 U.S. government bonds — 42,345 — 42,345 Total $ 13,520 $ 83,856 $ — $ 97,376
Summary of Estimated Value of Cash Equivalents and Debt Securities and Gross Unrealized Holding Gains and Losses	The following tables summarize the estimated value of the Company’s cash equivalents and debt securities and the gross unrealized holding gains and losses (in thousands): June 30, 2022 Amortized cost Unrealized gain Unrealized loss Estimated Fair Cash equivalents: Money market funds $ 22,101 $ — $ — $ 22,101 Total cash equivalents $ 22,101 $ — $ — $ 22,101 Debt securities: Corporate debt securities $ 38,829 $ — $ (302) $ 38,527 Commercial paper 10,942 — — 10,942 U.S. government bonds 56,210 — (459) 55,751 Total debt securities $ 105,981 $ — $ (761) $ 105,220 Classified as: Cash equivalents $ 22,101 Short-term debt securities 105,220 $ 127,321 December 31, 2021 Amortized cost Unrealized gain Unrealized loss Estimated Fair Cash equivalents: Money market funds $ 13,520 $ — $ — $ 13,520 Total cash equivalents $ 13,520 $ — $ — $ 13,520 Debt securities: Corporate debt securities $ 41,576 $ — $ (65) $ 41,511 U.S. government bonds 42,429 — (84) 42,345 Total debt securities $ 84,005 $ — $ (149) $ 83,856 Classified as: Cash equivalents $ 13,520 Short-term debt securities 66,594 Long-term debt securities 17,262 $ 97,376

Balance Sheet Components (Table

Balance Sheet Components (Tables)	6 Months Ended
	Jun. 30, 2022
Balance Sheet Related Disclosures [Abstract]
Schedule of Inventory	Inventories consist of the following (in thousands): June 30, December 31, Raw materials $ 1,056 $ 1,056 Work-in-progress 1,747 1,468 Finished goods 73 88 Total inventories $ 2,876 $ 2,612
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following (in thousands): June 30, December 31, Prepaid contract manufacturing costs $ 4,694 $ 3,695 Prepaid research costs 3,463 3,253 Prepaid insurance 1,295 631 Prepaid marketing 783 469 Other 1,762 1,313 Total prepaid expenses and other current assets $ 11,997 $ 9,361
Schedule of Components of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): June 30, December 31, Contract research costs $ 4,101 $ 4,760 Compensation and related benefits 2,404 3,131 Contract manufacturing costs 1,955 3,288 Product revenue reserves 1,789 1,846 Other 1,217 674 Total accrued liabilities $ 11,466 $ 13,699

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2022
Debt Disclosure [Abstract]
Schedule of Long-Term Debt and Unamortized Discount Balances	ebt and unamortized discount balances are as follows (in thousands): June 30, December 31, Face value of debt $ 40,074 $ 30,000 Exit fee 2,600 3,277 Unamortized debt discount associated with exit fee, debt issuance costs and loan origination fees (3,758) (1,482) Total debt, net 38,916 31,795 Less: current portion of debt — (7,809) Debt, net $ 38,916 $ 23,986

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2022
Share-based Payment Arrangement [Abstract]
Stock Option Activity	The following table summarizes stock option activity under the Company’s stock-based compensation plans during the six months ended June 30, 2022 (in thousands, except option and share data): Shares Number of Weighted- Weighted- Aggregate Outstanding as of December 31, 2021 1,327,645 5,262,185 $ 10.24 7.25 $ 530 Additional options authorized 1,728,441 — Granted (1,835,700) 1,835,700 $ 5.59 Restricted stock units granted (298,150) — Performance stock units granted (30,000) — Exercised — (17,599) $ 8.67 Forfeited 188,277 (188,277) $ 10.90 Restricted stock units forfeited 48,025 — Outstanding as of June 30, 2022 1,128,538 6,892,009 $ 8.99 7.67 $ 2,758 Vested and exercisable as of June 30, 2022 3,409,980 $ 10.79 6.23 $ 1,017
Weighted-average assumptions used in Black-Scholes Model to estimate fair value of stock options granted	The fair value of stock options was estimated using the following weighted-average assumptions: Three Months Ended June 30, Six Months Ended June 30, 2022 2021 2022 2021 Expected term (in years) 6.08-6.08 6.02-6.08 5.27-6.08 5.27-6.08 Volatility 70.15%-71.20% 73.18%-99.72% 68.71%-71.20% 72.39%-100.87% Risk free interest rate 2.84%-3.03% 1.02%-1.09% 1.76%-3.03% 0.62%-1.16% Dividend yield — — — —
Schedule of Nonvested Restricted Stock Units and Performance Stock Units Activity and Weighted Average Grant Date Fair Value	The following table summarizes RSU and PSU activity and weighted average grant date fair value for the six months ended June 30, 2022: Shares Weighted- Unvested shares as of December 31, 2021 623,000 $ 8.63 Granted 328,150 $ 5.37 Vested (85,106) $ 10.09 Forfeited (48,025) $ 7.89 Unvested shares as of June 30, 2022 818,019 $ 7.21
Summary of Non-cash Stock Based Compensation Expense	Total stock-based compensation expense recognized was as follows (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2022 2021 2022 2021 Research and development $ 820 $ 551 $ 1,445 $ 942 Selling, general and administrative 1,388 1,507 2,810 2,665 Total $ 2,208 $ 2,058 $ 4,255 $ 3,607

Commitments and Contingencies (

Commitments and Contingencies (Tables)	6 Months Ended
	Jun. 30, 2022
Leases [Abstract]
Maturity of Operating Leases Liabilities and Future Minimum Lease Payments	The maturities of the Company’s operating lease liabilities as of June 30, 2022 were as follows (in thousands): Undiscounted lease payments June 30, 2022 Remaining in 2022 $ 334 2023 115 2024 1 2025 1 Total undiscounted payments 451 Less: imputed interest 12 Present value of future lease payments 439 Less: current portion of operating lease liabilities 436 Operating lease liabilities $ 3

Net (Loss) Income Per Share (Ta

Net (Loss) Income Per Share (Tables)	6 Months Ended
	Jun. 30, 2022
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table sets forth the computation of basic and diluted net (loss) income per common share for the periods presented (in thousands, except share amounts): Three Months Ended Six Months Ended 2022 2021 2022 2021 Numerator: Net (loss) income $ (21,884) $ (19,174) $ (44,527) $ 10,074 Denominator: Weighted-average shares outstanding for basic net (loss) income per share 43,059,809 33,932,127 39,178,043 33,909,637 Effect of dilutive securities — — — 247,240 Weighted-average shares outstanding for diluted net (loss) income per share 43,059,809 33,932,127 39,178,043 34,156,877 Net (loss) income per share: Basic $ (0.51) $ (0.57) $ (1.14) $ 0.30 Diluted $ (0.51) $ (0.57) $ (1.14) $ 0.29
Summary of Potentially Dilutive Shares Excluded from Computation of Diluted Net Loss Per Share	The following table sets forth the outstanding potentially dilutive securities which have been excluded in the calculation of diluted net (loss) income per share because including such securities would be anti-dilutive (in common stock equivalent shares): Three Months Ended Six Months Ended 2022 2021 2022 2021 Options to purchase common stock 6,892,009 5,016,630 6,892,009 3,514,249 Restricted stock units (unvested) 818,019 224,504 818,019 105,965 ESPP 89,662 56,940 89,662 6,884 Total 7,799,690 5,298,074 7,799,690 3,627,098

Description of Business - Addit

Description of Business - Additional Information (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2022 USD ($) Segment	Dec. 31, 2021 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of operating segments | Segment	1
Cash, cash equivalents and short-term investments	$ 141,800
Cash and cash equivalents	36,572	$ 22,221
Debt securities, available-for-sale	105,200
Accumulated deficit	$ (384,944)	$ (340,417)

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2020	Dec. 31, 2021
Product Information [Line Items]
Accounts receivable, allowance for doubtful accounts		$ 0		$ 0			$ 0
Bad debt expense		0	$ 0	0	$ 0
Inventory write-down		0	0	0	0
Early access program term (in years)	1 year
Total revenue		4,091,000	2,097,000	6,764,000	5,743,000
Product revenue, net
Product Information [Line Items]
Total revenue		$ 3,341,000	$ 2,097,000	6,014,000	$ 5,743,000	$ 0
Autorisation Temporaire D Utlisation Member
Product Information [Line Items]
Total revenue				$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	6 Months Ended	12 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	$ 127,321,000	$ 97,376,000
Financial liabilities	0	0
Other-than-temporary impairment losses	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial assets	0	0
Financial liabilities	0	0
Transfers in or out of level 3	$ 0	$ 0

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value (Detail) - USD ($)	Jun. 30, 2022	Dec. 31, 2021
Financial assets:
Financial assets	$ 127,321,000	$ 97,376,000
Corporate debt securities
Financial assets:
Financial assets	38,527,000	41,511,000
Commercial paper
Financial assets:
Financial assets	10,942,000
U.S. government bonds
Financial assets:
Financial assets	55,751,000	42,345,000
Money market funds
Financial assets:
Financial assets	22,101,000	13,520,000
Level 1
Financial assets:
Financial assets	22,101,000	13,520,000
Level 1 | Corporate debt securities
Financial assets:
Financial assets	0	0
Level 1 | Commercial paper
Financial assets:
Financial assets	0
Level 1 | U.S. government bonds
Financial assets:
Financial assets	0	0
Level 1 | Money market funds
Financial assets:
Financial assets	22,101,000	13,520,000
Level 2
Financial assets:
Financial assets	105,220,000	83,856,000
Level 2 | Corporate debt securities
Financial assets:
Financial assets	38,527,000	41,511,000
Level 2 | Commercial paper
Financial assets:
Financial assets	10,942,000
Level 2 | U.S. government bonds
Financial assets:
Financial assets	55,751,000	42,345,000
Level 2 | Money market funds
Financial assets:
Financial assets	0	0
Level 3
Financial assets:
Financial assets	0	0
Level 3 | Corporate debt securities
Financial assets:
Financial assets	0	0
Level 3 | Commercial paper
Financial assets:
Financial assets	0
Level 3 | U.S. government bonds
Financial assets:
Financial assets	0	0
Level 3 | Money market funds
Financial assets:
Financial assets	$ 0	$ 0

Fair Value Measurements - Estim

Fair Value Measurements - Estimated Value of Cash Equivalents and Debt Securities and Gross Unrealized Holding Gains and Losses (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Cash Equivalents and Investment Securities [Line Items]
Cash equivalents, Amortized cost	$ 22,101	$ 13,520
Cash equivalents, Estimated Fair Value	22,101	13,520
Debt securities, Amortized cost	105,981	84,005
Debt securities, Unrealized gain	0	0
Debt securities, Unrealized loss	(761)	(149)
Debt securities, Estimated Fair Value	105,220	83,856
Assets, Fair Value	127,321	97,376
Short-term debt securities
Cash Equivalents and Investment Securities [Line Items]
Debt securities, Estimated Fair Value	105,220	66,594
Long-term debt securities
Cash Equivalents and Investment Securities [Line Items]
Debt securities, Estimated Fair Value		17,262
Corporate debt securities
Cash Equivalents and Investment Securities [Line Items]
Debt securities, Amortized cost	38,829	41,576
Debt securities, Unrealized gain	0	0
Debt securities, Unrealized loss	(302)	(65)
Debt securities, Estimated Fair Value	38,527	41,511
Assets, Fair Value	38,527	41,511
Commercial paper
Cash Equivalents and Investment Securities [Line Items]
Debt securities, Amortized cost	10,942
Debt securities, Unrealized gain	0
Debt securities, Unrealized loss	0
Debt securities, Estimated Fair Value	10,942
Assets, Fair Value	10,942
U.S. government bonds
Cash Equivalents and Investment Securities [Line Items]
Debt securities, Amortized cost	56,210	42,429
Debt securities, Unrealized gain	0	0
Debt securities, Unrealized loss	(459)	(84)
Debt securities, Estimated Fair Value	55,751	42,345
Assets, Fair Value	55,751	42,345
Money market funds
Cash Equivalents and Investment Securities [Line Items]
Cash equivalents, Amortized cost	22,101	13,520
Cash equivalents, Estimated Fair Value	22,101	13,520
Assets, Fair Value	22,101	13,520
Cash equivalents
Cash Equivalents and Investment Securities [Line Items]
Cash equivalents, Estimated Fair Value	$ 22,101	$ 13,520

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Inventory (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Raw materials	$ 1,056	$ 1,056
Work-in-progress	1,747	1,468
Finished goods	73	88
Total inventories	$ 2,876	$ 2,612

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Prepaid contract manufacturing costs	$ 4,694	$ 3,695
Prepaid research costs	3,463	3,253
Prepaid insurance	1,295	631
Prepaid marketing	783	469
Other	1,762	1,313
Total prepaid expenses and other current assets	$ 11,997	$ 9,361

Balance Sheet Components - Sc_3

Balance Sheet Components - Schedule of Components of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Contract research costs	$ 4,101	$ 4,760
Compensation and related benefits	2,404	3,131
Contract manufacturing costs	1,955	3,288
Product revenue reserves	1,789	1,846
Other	1,217	674
Total accrued liabilities	$ 11,466	$ 13,699

Bristol-Meyers Squibb License_2

Bristol-Meyers Squibb License Agreement - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended
	Mar. 31, 2022	Apr. 30, 2016	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Value of common stock issued during period			$ 20,564	$ 45,610	$ 52
Common Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Issuance of common stock (in shares)			2,686,288	5,841,786	0
Value of common stock issued during period			$ 2	$ 6
Licensing Agreements
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Up front cash payments		$ 2,000
BMS Transaction | Common Stock | Purchase Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Issuance of common stock (in shares)		157,587
Value of common stock issued during period		$ 3,200
BMS Transaction | Licensing Agreements | Development And Regulatory Milestones
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone obligations		61,000
BMS Transaction | Licensing Agreements | Commercial Sales | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone obligations		128,000
BMS Transaction | Licensing Agreements | Development Phase Two [Domain]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone obligations		$ 3,000
BMS Transaction | Licensing Agreements | Development Phase Three
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone obligations	$ 5,000

Asset Purchase Agreements - Add

Asset Purchase Agreements - Additional Information (Detail) - AbbVie Asset Purchase Agreement - USD ($) $ in Millions		6 Months Ended
	Nov. 20, 2020	Jun. 30, 2021
Asset Purchase Agreement And Related License Agreement [Line Items]
Payment for asset purchase agreement	$ 95
Progeria Research Foundation (PRF) Collaboration Agreement
Asset Purchase Agreement And Related License Agreement [Line Items]
Proceeds from sale		$ 46.5

Debt - Additional Information (

Debt - Additional Information (Detail) $ / shares in Units, $ in Thousands

3 Months Ended

6 Months Ended

Jun. 03, 2022 USD ($) $ / shares shares

Jun. 01, 2022 USD ($)

Oct. 06, 2021 USD ($)

Feb. 23, 2021 USD ($)

Mar. 05, 2019 USD ($)

Jun. 30, 2022 USD ($)

Mar. 31, 2022 USD ($)

Jun. 30, 2021 USD ($)

Jun. 30, 2022 USD ($)

Jun. 30, 2021 USD ($)

Dec. 31, 2021 USD ($)

Aug. 03, 2018 USD ($)

May 31, 2018 USD ($)

Dec. 31, 2016 USD ($)

Debt Instrument [Line Items]

Face value of term loan

$ 40,074

$ 40,074

$ 30,000

Interest Expense

934

$ 880

1,820

$ 1,765

Carrying value of debt

38,916

38,916

23,986

Value of common stock issued during period

20,564

$ 45,610

$ 52

Loan final repayment exit fees payable

2,600

2,600

$ 3,277

Loss on extinguishment of debt

(1,144)

$ 0

Oxford Loan | Amended Tranche A

Debt Instrument [Line Items]

Loan outstanding

$ 30,000

Amended Oxford Loan

Debt Instrument [Line Items]

Loan agreement, aggregate borrowing capacity

35,000

Percentage of exit fee on principal balance

7.50%

Loan outstanding

23,300

Borrowings from loan agreement

6,700

Loan final repayment exit fees payable

$ 2,300

Loan final repayment additional exit fees payable

1,000

Amended Oxford Loan | Secured Debt, Tranche B

Debt Instrument [Line Items]

Repayments of loan agreement exit fee

$ 900

Amended Oxford Loan | Secured Debt, Amended Tranche B

Debt Instrument [Line Items]

Loan agreement, remaining borrowing capacity

$ 5,000

Fifth Amended Oxford Loan

Debt Instrument [Line Items]

Interest payment period

17 months

Principal and interest payment period

19 months

Amendment fees payment

$ 200

Line of Credit | Secured Debt | Innovatus Stock Purchase Agreement

Debt Instrument [Line Items]

Value of common stock issued during period

5,000

Sale of common stock, shares issued (in shares) | shares

749,053

Sale of common stock (in USD per share) | $ / shares

$ 6.6751

Line of Credit | Innovatus Loan | Secured Debt

Debt Instrument [Line Items]

Loan agreement, aggregate borrowing capacity

$ 75,000

Debt Instrument, percent of interest due (in percent)

0.0225

Percentage of exit fee on principal balance

6.50%

Minimum cash balance of face value of loan (in percent)

0.05

Debt discount

200

200

Capitalized debt issuance costs

1,000

1,000

Interest Expense

300

300

Carrying value of debt

38,900

$ 38,900

Effective interest rate

10.13%

Line of Credit | Innovatus Loan | Secured Debt | Variable Rate Component One | Minimum

Debt Instrument [Line Items]

Minimum prime rate

3.50%

Line of Credit | Innovatus Loan | Secured Debt | Variable Rate Component Two

Debt Instrument [Line Items]

Minimum prime rate

3.75%

Line of Credit | Innovatus Loan | Secured Debt, Tranche A

Debt Instrument [Line Items]

Face value of term loan

40,000

$ 40,000

Line of Credit | Innovatus Loan | Secured Debt, Tranche B

Debt Instrument [Line Items]

Face value of term loan

17,500

17,500

Line of Credit | Innovatus Loan | Secured Debt, Tranche B and C

Debt Instrument [Line Items]

Face value of term loan

$ 35,000

35,000

Line of Credit | Oxford Loan

Debt Instrument [Line Items]

Loan agreement, aggregate borrowing capacity

$ 25,000

Line of Credit | Oxford Loan | Secured Debt

Debt Instrument [Line Items]

Face value of term loan

$ 33,500

Line of Credit | Oxford Loan | Secured Debt, Tranche A

Debt Instrument [Line Items]

Face value of term loan

$ 15,000

Line of Credit | Amendment | Secured Debt, Tranche B

Debt Instrument [Line Items]

Face value of term loan

$ 5,000

Line of Credit | Amendment | Secured Debt, Tranche C

Debt Instrument [Line Items]

Face value of term loan

$ 5,000

Line of Credit | Amended Oxford Loan | Amended Tranche A

Debt Instrument [Line Items]

Loan agreement, aggregate borrowing capacity

$ 30,000

Repayments of loan agreement exit fee

33,500

Accrued and unpaid interest

200

Loss on extinguishment of debt

$ 1,100

Other final payments

$ 3,300

Debt - Schedule of Long-Term De

Debt - Schedule of Long-Term Debt and Unamortized Discount Balances (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Debt Disclosure [Abstract]
Face value of debt	$ 40,074	$ 30,000
Exit fee	2,600	3,277
Unamortized debt discount associated with exit fee, debt issuance costs and loan origination fees	(3,758)	(1,482)
Total debt, net	38,916	31,795
Less: current portion of debt	0	(7,809)
Debt, net of current portion	$ 38,916	$ 23,986

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted (in shares)			1,835,700
Stock-based compensation expense	$ 2,208	$ 2,058	$ 4,255	$ 3,607
Total unrecognized compensation expense	$ 15,400		$ 15,400
Weighted-average period for recognition (in years)			2 years 10 months 24 days
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value of employee option grants (in USD per share)	$ 4.39	$ 6.07	$ 3.53	$ 7.36
Restricted Stock Units (RSU)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted (in shares)	0	298,150		203,500
Weighted-average grant date fair value of employee option grants (in USD per share)	$ 6.87	$ 5.22	$ 6.87	$ 9.99
Stock-based compensation expense	$ 500	$ 200	$ 900	$ 300
Total unrecognized compensation expense	$ 4,700		$ 4,700
Weighted-average period for recognition (in years)			2 years 6 months
Performance Stock Units (PSU)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted (in shares)	30,000	0	30,000	0
Stock options, vested (in shares)			0
Total unrecognized compensation expense	$ 4,700		$ 4,700
Weighted-average period for recognition (in years)			2 years 6 months
Inducement Plan 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock available for grant (in shares)		850,000
Number of shares available to be issued (in shares)	380,000		380,000

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	6 Months Ended	9 Months Ended
	Jun. 30, 2022 USD ($) $ / shares shares	Sep. 30, 2021
Shares Available for Grant
Shares available for grant, outstanding, beginning balance (in shares)	1,327,645
Shares available for grant, additional options authorized (in shares)	1,728,441
Shares available for grant, granted (in shares)	(1,835,700)
Shares available for grant, restricted stock units granted (in shares)	(298,150)
Shares available for grant, performance stock units granted (in shares)	(30,000)
Shares available for grant, forfeited (in shares)	188,277
Shares available for grant, restricted stock units forfeited (in shares)	48,025
Shares available for grant, outstanding, ending balance (in shares)	1,128,538
Number of Options
Number of options, outstanding, beginning balance (in shares)	5,262,185
Number of options, granted (in shares)	1,835,700
Number of options, exercised (in shares)	(17,599)
Number of options, forfeited (in shares)	(188,277)
Number of options, outstanding, ending balance (in shares)	6,892,009
Number of options, vested and exercisable (in shares)	3,409,980
Weighted- Average Exercise Price
Weighted-average exercise price, outstanding, beginning balance (in USD per share) | $ / shares	$ 10.24
Weighted-average exercise price, granted (in USD per share) | $ / shares	5.59
Weighted-average exercise price, exercised (in USD per share) | $ / shares	8.67
Weighted-average exercise price, forfeited (in USD per share) | $ / shares	10.90
Weighted-average exercise price, outstanding, ending balance (in USD per share) | $ / shares	8.99
Weighted-average exercise price, vested and exercisable (in USD per share) | $ / shares	$ 10.79
Stock Options Additional Disclosures
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	7 years 8 months 1 day	7 years 3 months
Aggregate intrinsic value, beginning balance | $	$ 530
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	7 years 8 months 1 day	7 years 3 months
Aggregate intrinsic value, ending balance | $	$ 2,758
Weighted average remaining contractual life, vested and exercisable (in years)	6 years 2 months 23 days
Aggregate intrinsic value, vested and exercisable | $	$ 1,017

Stock-Based Compensation - Weig

Stock-Based Compensation - Weighted-average assumptions used in Black-Scholes Model to estimate fair value of stock options granted (Detail) - Stock Options	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility, minimum	70.15%	73.18%	68.71%	72.39%
Volatility, maximum	71.20%	99.72%	71.20%	100.87%
Risk free interest rate, minimum	2.84%	1.02%	1.76%	0.62%
Risk free interest rate, maximum	3.03%	1.09%	3.03%	1.16%
Dividend yield		0%		0%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 7 days		5 years 3 months 7 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 29 days		6 years 29 days

Stock Based Compensation - Sche

Stock Based Compensation - Schedule of Nonvested Restricted Stock Units and Performance Stock Units Activity and Weighted Average Grant Date Fair Value (Detail)	6 Months Ended
	Jun. 30, 2022 $ / shares shares
RSU and PSU Roll Forward Activity
Stock options granted (in shares)	1,835,700
Restricted Stock Units and Performance Stock Unit
RSU and PSU Roll Forward Activity
Unvested shares, beginning balance (in shares)	623,000
Stock options granted (in shares)	328,150
Vested (in shares)	(85,106)
Forfeited (in shares)	(48,025)
Unvested shares, ending balance (in shares)	818,019
Weighted-Average
Weighted average grant-date fair value of options beginning balance (in USD per share) | $ / shares	$ 8.63
Weighted-average grant date fair value of employee option grants (in USD per share) | $ / shares	5.37
Weighted average grant-date fair value of options vested (in USD per share) | $ / shares	10.09
Weighted average grant-date fair value of options forfeited (in USD per share) | $ / shares	7.89
Weighted average grant-date fair value of options ending balance (in USD per share) | $ / shares	$ 7.21

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Non-cash Stock Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 2,208	$ 2,058	$ 4,255	$ 3,607
Research and development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	820	551	1,445	942
Selling, general and administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 1,388	$ 1,507	$ 2,810	$ 2,665

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 17,000	$ 11,000	$ 26,000	$ 30,000
Effective tax rate		0.20%	0.06%	0.20%

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2021	Oct. 31, 2017 USD ($) ft²
Other Commitments [Line Items]
Rent expense recognized for company's operating leases	$ 100,000	$ 100,000	$ 300,000	$ 300,000
Variable lease payments for operating leases	$ 23,000	$ 23,000	46,000	46,000
Operating cash outflows for operating lease liabilities			$ 300,000	$ 300,000
Weighted-average remaining lease term (in years)	8 months 12 days		8 months 12 days		1 year 2 months 12 days
Weighted-average discount rate (in percent)	9.15%		9.15%		9.15%
Palo Alto, California
Other Commitments [Line Items]
Total leased space | ft²						8,029
Lease renewal term						3 years
Security deposit of collateral for lease						$ 300,000

Commitments and Contingencies_2

Commitments and Contingencies - Maturity of Operating Leases Liabilities and Future Minimum Lease Payments (Detail) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Leases [Abstract]
Remaining in 2022	$ 334
2023	115
2024	1
2025	1
Total undiscounted payments	451
Less: imputed interest	12
Present value of future lease payments	439
Less: current portion of operating lease liabilities	436	$ 628
Operating lease liabilities	$ 3	$ 116

Net (Loss) Income Per Share - S

Net (Loss) Income Per Share - Schedule of Earnings per Share, Basic and Dilutive (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Numerator:
Net (loss) income	$ (21,884)	$ (22,643)	$ (19,174)	$ 29,248	$ (44,527)	$ 10,074
Denominator:
Basic (in shares)	43,059,809		33,932,127		39,178,043	33,909,637
Effect of dilutive securities
Effect on dilutive securities (in shares)	0		0		0	247,240
Weighted-average shares outstanding for diluted net (loss) income per share (in shares)	43,059,809		33,932,127		39,178,043	34,156,877
Net (loss) income per share:
Basic (in USD per share)	$ (0.51)		$ (0.57)		$ (1.14)	$ 0.30
Diluted (in USD per share)	$ (0.51)		$ (0.57)		$ (1.14)	$ 0.29

Net (Loss) Income Per Share -_2

Net (Loss) Income Per Share - Summary of Potentially Dilutive Shares Excluded from Computation of Diluted Net (Loss) Income Per Share (Details) - shares	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities	7,799,690	5,298,074	7,799,690	3,627,098
Options to purchase common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities	6,892,009	5,016,630	6,892,009	3,514,249
Restricted stock units (unvested)
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities	818,019	224,504	818,019	105,965
ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities	89,662	56,940	89,662	6,884