Gyre Therapeutics (GYRE) 10-K 31 Mar 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2021	Mar. 25, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Trading Symbol	CBIO
Entity Registrant Name	Catalyst Biosciences, Inc.
Entity Central Index Key	0001124105
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		31,477,053
Entity Public Float			$ 135,045,079
ICFR Auditor Attestation Flag	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common stock
Security Exchange Name	NASDAQ
Entity File Number	000-51173
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	56-2020050
Entity Address, Address Line One	611 Gateway Blvd
Entity Address, Address Line Two	Suite 710
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	871-0761
Document Annual Report	true
Document Transition Report	false
Auditor Firm ID	274
Auditor Name	EISNERAMPER LLP
Auditor Location	Philadelphia, Pennsylvania
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the Registrant's proxy statement for its 2022 Annual Meeting of Stockholders (the “Proxy Statement”), to be filed with the U.S. Securities and Exchange Commission, no later than 120 days after the Registrant’s fiscal year ended December 31, 2021, are incorporated by reference to Part III of this Annual Report on Form 10-K.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 44,347	$ 30,360
Short-term investments	2,504	48,994
Accounts receivable	1,818	3,313
Prepaid and other current assets	2,807	6,843
Total current assets	51,476	89,510
Long-term investments		2,543
Other assets, noncurrent	472	528
Right-of-use assets	2,744	1,832
Property and equipment, net	970	433
Total assets	55,662	94,846
Current liabilities:
Accounts payable	6,419	5,931
Accrued compensation	1,467	2,476
Deferred revenue	230	1,983
Other accrued liabilities	4,072	6,743
Operating lease liability	1,977	663
Total current liabilities	14,165	17,796
Operating lease liability, noncurrent	408	981
Total liabilities	14,573	18,777
Commitments and Contingencies (Note 7)
Stockholders’ equity:
Preferred stock, $0.001 par value, 5,000,000 shares authorized; zero shares issued and outstanding
Common stock, $0.001 par value, 100,000,000 shares authorized; 31,409,707 and 22,097,820 shares issued and outstanding at December 31, 2021 and 2020, respectively	31	22
Additional paid-in capital	443,752	390,803
Accumulated other comprehensive income		5
Accumulated deficit	(402,694)	(314,761)
Total stockholders’ equity	41,089	76,069
Total liabilities and stockholders’ equity	$ 55,662	$ 94,846

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	31,409,707	22,097,820
Common stock, shares outstanding	31,409,707	22,097,820

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Revenue:
License and collaboration revenue	$ 7,338	$ 20,948
Operating expenses:
Research and development	68,889	52,975
General and administrative	18,963	16,180
Total operating expenses	95,232	78,318
Loss from operations	(87,894)	(57,370)
Interest and other income (expense), net	(39)	1,129
Net loss	$ (87,933)	$ (56,241)
Net loss per share attributable to common stockholders, basic and diluted	$ (2.87)	$ (2.93)
Shares used to compute net loss per share attributable to common stockholders, basic and diluted	30,640,977	19,179,299
License
Revenue:
License and collaboration revenue		$ 15,100
Collaboration
Revenue:
License and collaboration revenue	$ 7,338	5,848
Cost of license
Operating expenses:
Cost of license and collaboration		3,102
Cost of collaboration
Operating expenses:
Cost of license and collaboration	$ 7,380	$ 6,061

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (87,933)	$ (56,241)
Other comprehensive loss:
Unrealized loss on available-for-sale debt securities	(5)	(29)
Total comprehensive loss	$ (87,938)	$ (56,270)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balance at Dec. 31, 2019	$ 68,336	$ 12	$ 326,810	$ 34	$ (258,520)
Balance (in shares) at Dec. 31, 2019		12,040,835
Stock-based compensation expense	3,627		3,627
Stock-based compensation expense		51,056
Issuance of common stock from ESPP purchases and stock option exercises	435		435
Issuance of common stock from ESPP purchases and stock option exercises, shares		82,853
Issuance of common stock for public offering, net of issuance costs	59,941	$ 10	59,931
Issuance of common stock for public offering, net of issuance costs, shares		9,923,076
Unrealized loss on available-for-sale debt securities	(29)			(29)
Net loss	(56,241)				(56,241)
Balance at Dec. 31, 2020	76,069	$ 22	390,803	5	(314,761)
Balance (in shares) at Dec. 31, 2020		22,097,820
Stock-based compensation expense	3,405		3,405
Stock-based compensation expense		56,912
Issuance of common stock from ESPP purchases and stock option exercises	303		303
Issuance of common stock from ESPP purchases and stock option exercises, shares		69,975
Issuance of common stock for public offering, net of issuance costs	49,250	$ 9	49,241
Issuance of common stock for public offering, net of issuance costs, shares		9,185,000
Unrealized loss on available-for-sale debt securities	(5)			$ (5)
Net loss	(87,933)				(87,933)
Balance at Dec. 31, 2021	$ 41,089	$ 31	$ 443,752		$ (402,694)
Balance (in shares) at Dec. 31, 2021		31,409,707

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Statement Of Stockholders Equity [Abstract]
Issuance costs of issuance of common stock for public offering	$ 3,563	$ 4,559

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating Activities
Net loss	$ (87,933)	$ (56,241)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	3,405	3,627
Depreciation and amortization	290	138
Changes in operating assets and liabilities:
Accounts receivable	1,495	11,687
Prepaid and other assets	3,880	(3,043)
Accounts payable	500	1,652
Accrued compensation and other accrued liabilities	(3,680)	82
Operating lease liability and right-of-use asset	41	67
Deferred revenue	(1,753)	(13,017)
Net cash flows used in operating activities	(83,755)	(55,048)
Investing Activities
Proceeds from maturities of short-term investments	49,028	107,565
Purchase of short-term and long-term investments		(97,635)
Purchases of property and equipment	(839)	(267)
Net cash flows provided by investing activities	48,189	9,663
Financing Activities
Issuance of common stock for public offering, net of issuance costs	49,250	59,941
Issuance of common stock from ESPP purchase and stock option exercises	303	435
Net cash flows provided by financing activities	49,553	60,376
Net increase in cash and cash equivalents	13,987	14,991
Cash and cash equivalents at beginning of the period	30,360	15,369
Cash and cash equivalents at end of the period	44,347	30,360
Supplemental Disclosure of Non-Cash Investing and Financing Activities:
Right-of-use assets obtained in exchange for operating lease liabilities	1,850	$ 476
Remeasurement of right-of-use asset due to operating lease modification	$ 624

Nature of Operations

Nature of Operations	12 Months Ended
	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Operations	1. Nature of Operations Catalyst Biosciences, Inc. and its subsidiary (the “Company” or “Catalyst”) is a fully integrated research and clinical development biopharmaceutical company with expertise in protease engineering, discovery, translational research, clinical development, and manufacturing. The Company is focused on advancing its protease product candidates in the fields of hemostasis and complement regulation. The Company is located in South San Francisco, California and operates in

Liquidity

Liquidity	12 Months Ended
	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Liquidity	2. The Company had a net loss of $87.9 million for the year ended December 31, 2021 and an accumulated deficit of $402.7 million as of December 31, 2021. The Company expects to continue to incur losses for the next several years. As of December 31, 2021, the Company had $46.9 million of cash, cash equivalents and short-term investments. Its primary uses of cash are to fund operating expenses, including research and development expenditures and general and administrative expenditures. Based on the current status of its research and development plans, the Company believes that its existing cash, cash equivalents and investments as of December 31, 2021 will be sufficient to fund its cash requirements for at least the next 12 months from the date of the filing of this report. If, at any time, the Company’s prospects for financing its research and development programs decline, the Company may decide to reduce research and development expenses by delaying, discontinuing or reducing its funding of one or more of its research or development programs. Alternatively, the Company might raise funds through strategic collaborations, public or private financings or other arrangements. Such funding, if needed, may not be available on favorable terms, or at all. The Company will continue to evaluate the impact of the novel coronavirus disease (“COVID-19”) pandemic on our business, operations, and cash requirements. For recent financing, see Note 14, Stockholders’ Equity

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	3. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements include the accounts of the Company and its subsidiary. Intercompany accounts and transactions, if applicable, have been eliminated in consolidation. The Company’s consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”). Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, allowance of doubtful accounts, operating lease right-of-use assets and liabilities, accrued expenses, income taxes and stock-based compensation. The Company bases its estimates on various assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates. Accounting Pronouncements Recently Adopted In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The adoption of ASU 2019-12 did not have a material impact on the Company’s consolidated financial statements. New Accounting Pronouncements – Issued But Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments In May 2021, the FASB issued ASU 2021-04, Earnings Per Share (Topic 260), Debt—Modifications and Extinguishments (Subtopic 470-50), Compensation—Stock Compensation (Topic 718), and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options Cash and Cash Equivalents The Company invests its excess cash in bank deposits, consisting primarily of money market mutual funds. The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. Fair Value of Financial Instruments The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the consolidated financial statements on a recurring basis. 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 fair value hierarchy requires that an entity maximize the use of observable inputs when estimating fair value. The fair value hierarchy includes the following three-level classification which is based on the market observability of the inputs used for estimating the fair value of the assets or liabilities being measured: Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability. Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets, which are three years for computer equipment and software, and three to seven years for furniture and leasehold improvements. Investments The Company invests its excess cash in investment grade, short to intermediate-term, fixed income securities and recognizes purchased securities on the settlement date. All investments have been classified as “available-for-sale” and are carried at estimated fair value based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments at the time of purchase and reevaluates such designation as of each consolidated balance sheet date. Unrealized gains and losses on available-for-sale debt securities are excluded from earnings and are reported as a component of comprehensive loss. Realized gains and losses and declines in fair value determined to be other-than-temporary, if any, on available-for-sale debt securities are included in interest and other income (expense), net. The cost of securities sold is based on the specific-identification method. Interest on short-term investments is included in interest and other income (expense), net. Revenue Recognition License and Collaboration Arrangements The Company may enter into collaboration arrangements that fall under the scope Collaborative Arrangements (Topic 808). The Company analyzes its collaboration arrangements to assess whether they are within the scope of ASC 808 to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. The accounting for some of the activities under collaboration arrangements may be analogized to ASC 606 for distinct units of account that are reflective of a vendor-customer relationship. Under ASC 606, in determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when the Company satisfies each performance obligation. If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues attributed to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgement to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time. At the inception of each arrangement that contain development milestones, the Company evaluates whether the development milestones included are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not generally considered probable of being achieved until those approvals are received. At the end of each reporting period, the Company re-evaluates the probability of achievement of any development milestones, and if necessary, adjusts its estimate of the transaction price. Any such adjustments would be recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. For research and development services, the Company elected the practical expedient to recognize revenue as the research and development services are invoiced. As the Company has a right to consideration from the collaboration agreement with Biogen International GmbH (“Biogen”), in an amount that corresponds directly with the value of the Company’s performance completed to date for the research services, the Company recognized revenue related to the research services as invoiced, in line with the practical expedient in ASC 606-10-55-18. The transaction price is allocated to each performance obligation on a relative stand-alone selling price (“SSP”) basis. The Company recognizes revenue as or when the performance obligations under the contract are satisfied. As part of the accounting for these arrangements, the Company must develop assumptions that require judgment to determine the timing of recognition and the SSP for each performance obligation identified in the contract. The SSP for licenses are calculated using the residual approach if the Company has not yet established a price for such license and the license has not previously been sold on a standalone basis. Otherwise, selling prices for licenses are determined using an income approach model and include key assumptions such as: development timeline, revenue forecast, commercialization expenses, discount rate and probabilities of technical and regulatory success. To estimate the SSP for research and development services, the Company uses a cost-plus margin approach. Cost of License and Collaboration Cost of license revenue includes sublicense fees paid or payable to Mosaic Biosciences, Inc. (“Mosaic”), incurred in the period, under the terms of the Mosaic collaboration agreement, and fees for patent development and protection paid or payable to other third-party vendors corresponding to the recognition of license revenue from the Company’s collaboration agreement with Biogen. See Notes 8 and 12, Related Parties and Collaborations, respectively. Cost of license revenue does not include any allocated overhead costs. Cost of collaboration revenue includes fees for research and development services paid or payable to Mosaic and other third-party vendors and personnel cost, incurred in the period pertaining to the Company’s agreement with Biogen. See Notes 8 and 12, Related Parties and Collaborations, respectively. Cost of collaboration revenue does not include any allocated overhead costs. Research and Development Expenses Research and development costs are expensed as incurred. Nonrefundable advance payments for goods or services used in research and development are initially deferred and capitalized in prepaid and other current assets. The capitalized amounts are then expensed as the related goods are delivered or services are performed, or until it is no longer expected that the goods or services will be delivered. Research and development costs consist of payroll and other personnel-related expenses, laboratory supplies and reagents, contract research and development services, materials, and consulting costs, as well as allocations of facilities and other overhead costs. Under the Company’s collaboration agreement with Biogen, certain specific expenditures are reimbursed by third parties. During the years ended December 31, 2021 and 2020, $6.5 million and $5.4 million, respectively, of research and development expense was recorded as cost of collaboration revenue related to the collaboration agreement with Biogen signed in December 2019. Accrued Research and Development Expenses Accrued expenses include estimated costs of research and development activities conducted by external service providers, which include the conduct of preclinical studies and clinical trials 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 other accrued liabilities in the consolidated balance sheet and within research and development expense in the consolidated statement of operations. These costs are a significant component of the research and development expenses. The Company records accrued expenses for these costs based on the estimated amount of work completed and in accordance with agreements established with these external service providers. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash, cash equivalents, investments and accounts receivable. The Company’s investment policy restricts cash investments to high credit quality, investment grade investments. The Company believes that it has established guidelines for investment of its excess cash that maintain safety and liquidity through its policies on high quality of investment and investment duration. The Company is exposed to credit risk in the event of default by the institutions holding the cash and cash equivalents to the extent beyond the amount insured by the federal depository insurance corporation. The Company’s accounts receivable as of December 31, 2021 of $1.8 million as well as its total license and collaboration revenue of $7.3 million and $20.9 million for the years ended December 31, 2021 and 2020, respectively, are from one party, see Note 12, Collaborations Accounts Receivable and Allowance for Doubtful Accounts Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional. Customer payments are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until the Company performs its obligations under the arrangements. The Company continuously monitors collections and payments from its customers and maintains a provision for estimated credit losses. The Company determines its allowance for doubtful accounts by considering a number of factors, including the length of time balances are past due, the Company’s previous loss history, the customer’s current ability to pay its obligations to the Company and the condition of the general economy and the industry as a whole. The Company writes off accounts receivable when they are determined to be uncollectible. For the years ended December 31, 2021 and 2020, there were no allowance for doubtful accounts deemed necessary. Income Taxes Income taxes are computed using the liability method. Deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company follows the authoritative guidance on accounting for uncertainty in income taxes. This guidance prescribes a more-likely-than-not threshold for financial statement recognition and measurement of a tax position taken in the Company’s income tax returns. This interpretation also provides guidance on accounting for interest and penalties and associated with tax positions, accounting for income taxes in interim periods and income tax disclosures. The Company’s policy is to include penalties and interest expense related to income taxes as a component of other expense and interest expense, respectively, as necessary. Stock-Based Compensation The Company measures the cost of employee, non-employee and director services received in exchange for an award of equity instruments based on the fair value of the award on the date of grant and recognizes the related expense over the period during which the employee, non-employee or director is required to provide service in exchange for the award on a straight-line basis. 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. The Company uses the Black-Scholes option-pricing valuation model to estimate the grant-date fair value of stock-based awards. The determination of fair value for stock-based awards on the date of grant using an option-pricing model requires management to make certain assumptions regarding a number of variables. T he Company elected to account for forfeitures when they occur. As such, the Company recognizes stock-based compensation expense, over their requisite service period, based on the vesting provisions of the individual grants. Restructuring Charges Costs and liabilities associated with restructuring are recorded in the period management commits to a restructuring or cost reduction plan, or executes specific actions contemplated by the plan and all criteria for liability recognition have been met. One-time employee termination costs are recognized at the time of communication to employees, unless future service is required, in which case the costs are recognized ratably over the future service period. Restructuring charges are recognized as an operating expense within the consolidated statements of operations and related liabilities are recorded within accrued compensation on the consolidated balance sheets. The Company periodically evaluates and, if necessary, adjusts its estimates based on currently available information. Leases At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances present. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes its incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. Certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received. The Company has elected to combine lease and non-lease components as a single component. The lease expense is recognized over the expected term on a straight-line basis. Operating leases are recognized on the consolidated balance sheet as right-of-use assets, operating lease liabilities, current and operating lease liabilities, non-current. Net Loss per Share Attributable to Common Stockholders Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss of the Company for all periods presented.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements For a description of the fair value hierarchy and fair value methodology, see Note 3, Summary of Significant Accounting Policies The following tables present the fair value hierarchy for assets measured at fair value on a recurring basis as of December 31, 2021 and 2020 (in thousands) December 31, 2021 Level 1 Level 2 Level 3 Total Financial assets: Money market funds ( 1) $ 44,347 $ — $ — $ 44,347 U.S. government agency securities ( 2) 2,504 — — 2,504 Total financial assets $ 46,851 $ — $ — $ 46,851 December 31, 2020 Level 1 Level 2 Level 3 Total Financial assets: Money market funds ( 1) $ 30,360 $ — $ — $ 30,360 U.S. government agency securities ( 2) 37,837 — — 37,837 Federal agency securities ( 2) — 13,700 — 13,700 Total financial assets $ 68,197 $ 13,700 $ — $ 81,897 (1) Included in cash and cash equivalents on accompanying consolidated balance sheet. (2) Included in short-term investments on accompanying consolidated balance sheet and are classified as available-for-sale debt securities. $2.5 million of U.S. government agency securities as of December 31, 2020 are included in long-term investments on the accompanying consolidated balance sheets due to the maturity being more than 12 months. The carrying amounts of cash, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to the short-term maturity of these instruments.

Financial Instruments

Financial Instruments	12 Months Ended
	Dec. 31, 2021
Investments All Other Investments [Abstract]
Financial Instruments	5. Financial Instruments Cash equivalents and investments (debt securities) which are classified as available-for-sale securities, consisted of the following (in thousands) December 31, 2021 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds (cash equivalents) $ 44,347 $ — $ — $ 44,347 U.S. government agency securities 2,504 — — 2,504 Total financial assets $ 46,851 $ — $ — $ 46,851 Classified as: Cash and cash equivalents $ 44,347 Short-term investments 2,504 $ 46,851 December 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds (cash equivalents) $ 30,360 $ — $ — $ 30,360 U.S. government agency securities 37,835 2 — 37,837 Federal agency securities 13,697 3 — 13,700 Total financial assets $ 81,892 $ 5 $ — $ 81,897 Classified as: Cash and cash equivalents $ 30,360 Short-term investments 48,994 Long-term investments 2,543 $ 81,897 There have been no material realized gains or losses on available-for-sale debt securities for the periods presented. As of December 31, 2021, the remaining contractual maturities of $2.5 million of available-for-sale debt securities were less than one year.

Other Accrued Liabilities

Other Accrued Liabilities	12 Months Ended
	Dec. 31, 2021
Payables And Accruals [Abstract]
Other Accrued Liabilities	6. Other Accrued Liabilities Other accrued liabilities consisted of the following (in thousands) Year Ended December 31, 2021 2020 Manufacturing $ 1,381 $ 2,238 Biogen 868 — Pre-clinical 773 — Professional and consulting services 509 3,979 Clinical 361 291 Other 180 235 Total other accrued liabilities $ 4,072 $ 6,743

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Manufacturing Agreements On May 20, 2016, the Company signed a development and manufacturing services agreement with AGC Biologics, Inc. (“AGC”), pursuant to which AGC will conduct manufacturing development of agreed upon product candidates. The Company had firm work orders with AGC to manufacture MarzAA and DalcA to support its clinical trials totaling $15.8 million and the payment obligations were fully paid off as of December 31, 2021. The Company also signed an agreement with AGC to perform certain manufacturing services related to the Company’s collaboration agreement with Biogen, which includes firm work orders totaling $0.7 million and the payment obligations remaining as of December 31, 2021 were $0.3 million. In July 2021, the Company entered into two separate agreements, one for additional clinical trial services for MarzAA, and another for the Company’s screening and natural history of disease clinical studies related to CFI deficiency, with total payments of up to $3.2 million and $6.5 million, respectively. In November 2021, the Company provided notice of intent to terminate its MarzAA manufacturing agreements and incurred charges of $3.8 million to write-off prepaid manufacturing costs that will no longer be used for the clinical development of MarzAA, see Note 16, Restructuring On September 16, 2021, the Company signed a Manufacturing and Research and Development Studies Agreement to support the lyophilized drug product, CB4332. The agreement will cover analytical method qualification to support good manufacturing practices (“GMP”) manufacturing. The Company currently has firm work orders related to this agreement totaling $0.2 million and the payment obligations were fully paid off as of December 31, 2021. COVID-19 The current COVID-19 pandemic has presented a substantial public health and economic challenge around the world and is affecting the Company’s employees, potential trial participants and business operations. The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition will depend on future developments that are highly uncertain and cannot be accurately predicted, including new information that may emerge concerning COVID-19, the actions taken to contain it or treat its impact and the economic impact on local, regional, national, and international markets. The COVID-19 pandemic may disrupt the operations of the Company’s manufacturers or disrupt supply logistics, which could impact the timing of deliveries and potentially increase expenses under our agreements. The Company is actively monitoring the impact of COVID-19 and the possible effects on its financial condition, liquidity, operations, clinical trials, suppliers, industry and workforce.

Related Parties

Related Parties	12 Months Ended
	Dec. 31, 2021
Related Party Transactions [Abstract]
Related Parties	8 . Related Parties On October 24, 2017, the Company announced a strategic research collaboration with Mosaic to develop intravitreal anti-complement factor C3 products for the treatment of dry AMD and other retinal diseases. Dr. Usman, the Company’s Chief Executive Officer and a member of the Company’s board of directors, and Mr. Lawlor, a member of the Company’s board of directors, were also members of the board of directors of Mosaic. On December 21, 2018, the Company amended its collaboration agreement with Mosaic to, among other things, include certain additional products. According to the Mosaic collaboration agreement, as amended, the Company and Mosaic co-funded certain research. On December 18, 2019, the Company entered into the second amendment to the Mosaic collaboration agreement following completion of the co-funded research. Pursuant to the second amendment, any future services provided by Mosaic will be performed on a fee-for-service basis. In connection with the Company’s collaboration agreement with Biogen, the Company received a $15.0 million upfront license fee on January 10, 2020, see Note 12, Collaborations On May 8, 2020, the Company entered into a subsequent amendment to the Mosaic collaboration agreement. As part of this amendment, the Company paid a one-time $0.8 million cash payment to Mosaic, and Mosaic is eligible to receive up to $4.0 million in potential future milestone payments related to regulatory and clinical development events for CB 2782-PEG and an additional anti-complement product candidate in lieu of the Company’s obligations to pay Mosaic a double-digit percentage of funds the Company receives from Biogen or any other amounts the Company receives related to sublicense fees, research and development payments, or any other research, regulatory, clinical or commercial milestones and royalties on any other development candidates. The Company now owns one hundred percent of all future payment streams related to these product candidates. As of June 30, 2020, Mosaic was no longer a related party.

Leases

Leases	12 Months Ended
	Dec. 31, 2021
Lessee Disclosure [Abstract]
Leases	9. Leases Operating lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term. In calculating the present value of the lease payments, the Company has elected to utilize its incremental borrowing rate based on the original lease term and not the remaining lease term. The lease includes non-lease components ( e.g. The Company leases office space for its corporate headquarters, located in South San Francisco, CA. The lease term is through April 30, 2023 and there are no stated renewal options. On July 17, 2020, the Company entered into an amendment to its existing lease agreement to lease additional office space for an aggregated undiscounted future monthly payment of $0.5 million. The amendment was treated as a separate lease with a lease term of 2.6 years and commenced during the fourth quarter of 2020. In April 2021, the Company entered into a license agreement (the “License Agreement”) for the use of laboratory facilities in South San Francisco, CA, for an aggregated undiscounted future payment of $1.9 million. This License Agreement has an original lease term of one year and a renewal period of six months. This License Agreement commenced during the second quarter of 2021. In October 2021, the Company amended the License Agreement to extend the lease term for a period of one year. The amendment was not accounted for as a separate lease, and resulted in an adjustment to the right-of-use asset and lease liability of $ 0.6 million . The amended lease will expire at the end of April 2023. For the years ended December 31, 2021 and 2020, the Company’s operating lease expense was $1.7 million and $0.7 million, respectively. The present value assumptions used in calculating the present value of the lease payments were as follows: December 31, 2021 2020 Weighted-average remaining lease term 1.3 years 2.3 years Weighted-average discount rate 4.8 % 5.7 % The maturity of the Company’s operating lease liabilities as of December 31, 2021 were as follows (in thousands): Year Ending December 31, Amount 2022 $ 2,044 2023 410 Total undiscounted lease payments 2,454 Less: imputed interest (69 ) Total operating lease liability $ 2,385 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. The Company did not incur significant variable lease costs for the years ended December 31, 2021 and 2020. Supplemental cash flow information related to operating leases was as follows (in thousands) Year Ended December 31, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities $ 1,641 $ 602 Prepaid cash payment for lease 208 — Cash paid for operating leases that were included in operating cash outflows $ 1,849 $ 602

Stock Based Compensation

Stock Based Compensation	12 Months Ended
	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Based Compensation	10. Stock Based Compensation 2018 Omnibus Incentive Plan In June 2018, stockholders of the Company approved the Company’s 2018 Omnibus Incentive Plan (the “2018 Plan”). The 2018 Plan had previously been approved by the Company’s Board of Directors (the “Board”) and the Compensation Committee (the “Committee”) of the Board, subject to stockholder approval. The 2018 Plan became effective on June 13, 2018. On June 9, 2021, the stockholders of the Company approved an amendment previously approved by the Board to increase the number of shares of common stock reserved for issuance under the 2018 Plan by 2,500,000 to a total of 5,300,000 shares. The amendment became effective immediately upon stockholder approval. Performance-Based Stock Option Grants In February 2021, the Committee approved the issuance of option grants to purchase 647,000 shares of common stock for executive officers pursuant to the 2018 Plan, which will vest upon (a) the achievement of specified performance goals and (b) the grantees’ continued employment during the service period specified in each grant. For the year ended December 31, 2021, no expense has been recognized related to these awards. In addition, the options never vested and expired since the performance conditions were not satisfied as of December 31, 2021. The following table summarizes stock option activity under the Company’s 2018 Plan and related information: Number of Shares Underlying Outstanding Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (thousands) Outstanding — December 31, 2019 1,577,541 $ 10.85 8.15 $ 1,350 Options granted 1,091,250 6.26 Options exercised (44,605 ) 5.04 Options forfeited (250,641 ) 10.32 Options expired (17,930 ) 51.12 Outstanding — December 31, 2020 2,355,615 $ 8.59 7.96 $ 1,337 Options granted 1,493,238 5.31 Options exercised (5,000 ) 4.63 Options forfeited (1,239,630 ) 6.26 Options expired (593 ) 566.33 Outstanding — December 31, 2021 2,603,630 $ 7.70 7.46 $ — Exercisable — December 31, 2021 1,513,039 $ 9.37 6.35 $ — Shares available to be granted — December 31, 2021 3,333,791 The weighted-average grant date fair value of options granted during the years ended December 31, 2021 and 2020 was $4.00 and $5.20, respectively. The aggregate intrinsic value of options exercised during the years ended December 31, 2021 and 2020 was $3,000 and $0.1 million, respectively. The fair value of options vested during the years ended December 31, 2021 and 2020 was $2.6 million and $3.0 million, respectively. Valuation Assumptions The Company estimated the fair value of stock options granted using the Black-Scholes option-pricing formula and a single option award approach. Due to its limited history as a public company and limited number of sales of its common stock, the Company estimated its volatility considering a number of factors including the use of the volatility of comparable public companies. The expected term of options granted under the Plan, all of which qualify as “plain vanilla” per SEC Staff Accounting Bulletin 107, is determined based on the simplified method due to the Company’s limited operating history. The risk-free rate is based on the yield of a U.S. Treasury security with a term consistent with the option. This fair value is being amortized ratably over the requisite service periods of the awards, which is generally the vesting period. The fair value of employee stock options was estimated using the following weighted-average assumptions: Year Ended December 31, 2021 2020 Employee Stock Options: Expected term (in years) 6.00 5.81 Risk-free interest rate 0.84 % 0.91 % Dividend yield — — Volatility 93.25 % 113.36 % Total stock-based compensation recognized was as follows (in thousands): Year Ended December 31, 2021 2020 Research and development $ 1,202 $ 1,487 General and administrative (1) 2,203 2,140 Total stock-based compensation $ 3,405 $ 3,627 (1) Included in general and administrative stock-based compensation for the years ended December 31, 2021 and 2020 is $0.3 million and $0.3 million in expense related to 56,912 shares and 51,056 shares of common stock, respectively, issued to certain board members in lieu of their cash compensation. As of December 31, 2021, the Company had unrecognized employee stock-based compensation expense of $3.9 million, related to unvested stock option awards, which is expected to be recognized over an estimated weighted-average period of 2.49 years. Employee Stock Purchase Plan In June 2018, the Company’s stockholders approved the 2018 Employee Stock Purchase Plan (the “ESPP”). The ESPP had previously been approved by the Board and the Compensation Committee of the Board, subject to stockholder approval which became effective as of June 13, 2018. Under the ESPP, employees meeting certain specific employment qualifications are eligible to participate and can purchase shares of common stock semi-annually on February 9 th th The Company’s ESPP is subject to an Evergreen provision which shares may be added to the pool as needed. As of December 31, 2021, a total of 359,545 shares of common stock may be granted in accordance with the terms of the ESPP. For the year ended December 31, 2021, a total of 64,975 shares of common stock for $0.3 million have been issued to employees participating in the two ESPP purchases during 2021 and 235,469 shares are available for issuance under the ESPP as of December 31, 2021. Stock-based compensation expense for the ESPP was $0.1 million and $0.1 million for the years ended December 31, 2021 and 2020, respectively, and is included in total stock-based compensation recognized.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes The Company has incurred cumulative net operating losses since inception and, consequently, has not recorded any income tax expense for the years ended December 31, 2021 and 2020 due to its net operating loss position. The reconciliation of the federal statutory income tax rate to the Company’s effective tax rate for the years ended December 31, 2021 and 2020 are as follows: Year Ended December 31, 2021 2020 Tax at statutory federal rate -21.00 % -21.00 % State Tax (benefit)—net of federal benefit 0.00 % 0.00 % Permanent differences 0.35 % 0.58 % Tax credits -5.86 % -12.26 % Derecognition due to Sec. 382 and 383 limitations 0.00 % 44.55 % Change in valuation allowance 26.26 % -12.25 % Other 0.25 % 0.38 % Effective tax rate 0.00 % 0.00 % Significant components of the Company’s deferred tax assets as of December 31, 2021 and 2020 consist of the following (in thousands): Year Ended December 31, 2021 2020 Deferred tax assets: Accruals and reserves $ 1,000 $ 1,095 Net operating loss carry forwards 47,541 29,505 Tax credit carry forwards 12,939 7,789 Fixed and intangible assets 3 7 Valuation allowance (61,483 ) (38,396 ) Net deferred tax assets: $ — $ — Based on the available objective evidence at December 31, 2021, the Company does not believe it is more likely than not that the net deferred tax assets will be realizable. Accordingly, the Company has provided a full valuation allowance against its net deferred tax assets at December 31, 2021 and 2020. The net valuation allowance increased by approximately $23.1 million and decreased approximately $6.9 million during the years ended December 31, 2021 and 2020, respectively. As of December 31, 2021, after consideration of certain limitations (see below), the Company had approximately $226.4 million federal and $8.0 million state net operating loss carryforwards (“NOL”) available to reduce future taxable income which, if unused, will begin to expire in 2037 for federal and 2032 for state tax purposes. The federal net operating loss carryforward includes $218.9 million that have an indefinite life. As of December 31, 2021, the Company also had tax credit carry forwards available to offset future tax liabilities of approximately $11.4 million for federal and $7.5 million for state. If unused, the federal credit will begin to expire in 2040 and the state tax credit does not expire. If the Company experiences a greater than 50 percentage point aggregate change in ownership over a three-year period (a Section 382 ownership change), utilization of its pre-change NOL carry forwards are subject to annual limitation under Section 382 of the Internal Revenue Code (California has similar provisions). The annual limitation is determined by multiplying the value of the Company's stock at the time of such ownership change by the applicable long-term tax-exempt rate. Such limitations may result in expiration of a portion of the NOL carryforwards before utilization. The Company determined that ownership changes occurred December 21, 2007, August 20, 2015, April 13, 2017, February 15, 2018, and February 18, 2020. Approximately $156.3 million and $70.8 million of the NOLs will expire unutilized for federal and California purposes, respectively. The Company has derecognized NOL related deferred tax assets in the tax affected amounts of $32.8 million and $0 for federal and California purposes, respectively. All of the federal tax credits could expire unutilized as well, whereas none of the California tax credits are subject to expiration. Approximately $15.2 million of gross federal tax credit-related deferred tax assets were derecognized due to the Section 383 limitation. The ability of the Company to use its remaining NOL and tax credit carry forwards may be further limited if the Company experiences a Section 382 ownership change as a result of future changes in its stock ownership. On March 27, 2020, the “Coronavirus Aid, Relief and Economic Security (CARES) Act” (the “Act”) was signed into law. The Act includes provisions relating to refundable payroll tax credits, deferment of the employer portion of certain payroll taxes, net operating loss carryback periods, alternative minimum tax credit refunds, and modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. The Company analyzed the provisions of the Act and determined there was no significant impact to its 2020 tax provision. On June 29, 2020, the California Governor signed Assembly Bill 85 (“A.B. 85”), which now becomes California law. A.B. 85, which includes several tax measures, provides for a three-year suspension of the use of net operating losses for medium and large businesses and a three-year cap on the use of business incentive tax credits to offset no more than $5.0 million of tax per year. Generally, A.B. 85 suspends the use of net operating losses for taxable years 2020, 2021, and 2022 for taxpayers with taxable income of $1.0 million or more. Since the Company is not expected to generate California source taxable income of more than $1.0 million, no material impact is anticipated at this time. On December 27, 2020, the “Consolidated Appropriations Act, 2021” (the “CAA”) was signed into law. The CAA includes provisions meant to clarify and modify certain items put forth in CARES Act, while providing aid to businesses affected by the pandemic. The CAA allows deductions for expenses paid for by Paycheck Protection Program (“PPP”) and Economic Injury Disaster Loan (“EIDL”) Program, clarifies forgiveness of EIDL advances, and other business provisions. The Company analyzed the provisions of the CAA and determined there was no significant impact to its 2021 tax provision. Accounting for Uncertainty in Income Taxes The Company only recognizes tax benefits if it is more likely than not that they will be sustained upon audit by the relevant tax authority based upon their technical merits. An uncertain tax position will not be recognized if it has less than a 50% likelihood of being sustained. The Company had approximately $4.7 million and $3.0 million of unrecognized tax benefits as of December 31, 2021 and 2020, respectively. As the Company has a full valuation allowance on its deferred tax assets, the unrecognized tax benefits have reduced the deferred tax assets and the valuation allowance in the same amount. The Company does not expect the amount of unrecognized tax benefits to materially change in the next twelve months. A reconciliation of the beginning and ending balance of the unrecognized tax benefits is as follows (in thousands) Beginning Balance at January 1, 2020 $ 1,871 Increase/(Decrease) of unrecognized tax benefits taken in prior years (295 ) Increase/(Decrease) of unrecognized tax benefits related to current year 1,379 Ending Balance at December 31, 2020 $ 2,955 Increase/(Decrease) of unrecognized tax benefits taken in prior years — Increase/(Decrease) of unrecognized tax benefits related to current year 1,749 Ending Balance at December 31, 2021 $ 4,704 Interest and penalties related to unrecognized tax benefits would be included as income tax expense in the Company’s consolidated statements of operations. As of December 31, 2021 and 2020, the Company had not recognized any tax-related penalties or interest in its consolidated financial statements. The Company files income tax returns in the United States federal, California, Kansas, Missouri and New Jersey state jurisdictions. The Company is not currently under examination by income tax authorities in federal, state or other jurisdictions. As of December 31, 2021 and 2020, the Company had no uncertain tax positions which affected its financial position and its results of operations or its cash flow, and will continue to evaluate for uncertain positions in the future. The Company is subject to United States federal and state income tax examinations by authorities for all tax years due to accumulated net operating losses that are being carried forward for tax purposes.

Collaborations

Collaborations	12 Months Ended
	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaborations	12. Collaborations Mosaic In October 2017, the Company entered into a strategic research collaboration with Mosaic to develop intravitreal anti-complement factor 3 (C3) products for the treatment of dry Age-related Macular Degeneration (AMD) and other retinal diseases. The Company entered into two amendments to the Mosaic research collaboration agreements in December 2019 and May 2020. See Note 8, Related Parties ISU Abxis In December 2018, the Company entered into an amended and restated license agreement with ISU Abxis (the “A&R ISU Abxis Agreement”), which amended and restated its previous license and collaboration agreement with ISU Abxis previously entered into in September 2013, as subsequently amended in October 2014 and December 2016 (the “Original ISU Abxis Agreement”) ISU Abxis will receive commercialization rights in South Korea to the Company’s engineered Factor IX dalcinonacog alfa - DalcA and the Company will receive clinical development and commercialization rights in the rest of world (excluding South Korea) and manufacturing development and manufacturing rights worldwide (including South Korea) The eliminates the profit-sharing arrangement in the Original ISU Abxis Agreement and rovides for a low single-digit royalty payment to ISU Abxis, on a country-by-country basis, for net product sales of DalcA by the Company or its affiliates in each country other than South Korea. Pursuant to the A&R , the Company will also pay up to an aggregate of $19.5 million in milestone payments to ISU Abxis, including $2.5 million in regulatory and development milestone payments and up to $17.0 million in commercial milestone payments, if the applicable milestones are met. As of December 31, 2021, no milestones have been met. Biogen On December 18, 2019, the Company and Biogen entered into a License and Collaboration Agreement (the “Biogen Agreement”), under which the Company granted Biogen a worldwide, royalty-bearing, exclusive, with the right to sublicense, license (“Exclusive License”) to develop and commercialize CB 2782-PEG and other anti-C3 proteases for potential treatment of dry AMD and other disorders. Pursuant to the Biogen Agreement, the Company will perform certain pre-clinical and manufacturing activities (“Research Services”), and Biogen will be solely responsible for funding the pre-clinical and manufacturing activities and performing IND-enabling activities, worldwide clinical development, and commercialization. The Company will provide the Research Services over a term of thirty months twelve-month Under the terms of the Biogen Agreement, the Company received an up-front payment for the transfer of the Exclusive License (inclusive of certain know-how) of $15.0 The Company determined that the performance obligations under the Biogen Agreement were the Exclusive License and the Research Services. For the Exclusive License, the Company used the residual approach in determining the standalone selling price, or SSP, which includes the upfront payments, milestones and royalties. For the Research Services, the Company used the historical pricing approach for determining the SSP, which includes the reimbursement of personnel and out-of-pocket costs. The Biogen Agreement will continue on a product-by-product and country-by-country basis until the tenth anniversary of the first commercial sale of the first product in a country, unless terminated earlier by either party as specified under the agreement. In March 2022, the Company received written notice from Biogn to terminate the Biogen Agreement effective in May 2022. See Note 17, Subsequent Event For the year ended December 31, 2021, the Company recognized no license revenue from the Biogen Agreement. For the year ended December 31, 2020, the Company recognized the $15.0 million in license revenue upon the transfer of the Exclusive License and the related know-how, and $0.1 million in license revenue for reimbursable out-of-pocket costs incurred. For the years ended December 31, 2021 and 2020, the Company recognized $7.3 million and $5.8 million in collaboration revenue for reimbursable out-of-pocket and personnel costs incurred related to Research Services. For the year ended December 31, 2021, the Company recognized $2.0 million in collaboration revenue from the beginning of period deferred revenue balance.

Interest and Other Income (Expe

Interest and Other Income (Expense), Net	12 Months Ended
	Dec. 31, 2021
Other Income And Expenses [Abstract]
Interest and Other Income (Expense), Net	13. Interest and Other Income (Expense), Net The following table shows the detail of interest and other income (expense), net as follows (in thousands): Year Ended December 31, 2021 2020 Interest income $ 39 $ 561 Miscellaneous income 9 659 Other (87 ) (91 ) Total interest and other income (expense), net $ (39 ) $ 1,129

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Stockholders' Equity	14. Stockholders’ Equity In the first quarter of 2021, the Company issued and sold an aggregate of 9,185,000 registered shares of its common stock (including 485,000 shares sold pursuant to the exercise of the underwriters’ overallotment option) at a price of $5.75 per share. The net proceeds to the Company, after deducting $3.6 million in underwriting discounts and commissions, and offering expenses, were approximately $49.3 million. The Company had 85 issued and outstanding common stock warrants as of December 31, 2021 and 2020, respectively, with a weighted-average exercise price of $392.70. The warrants expire in August 2022 2021 ATM Program On October 15, 2021, the Company entered into an Equity Distribution Agreement (the “ATM Agreement”) with Piper Sandler & Co. (“Piper Sandler”), as sales agent, pursuant to which the Company may offer and sell, from time to time, through Piper Sandler, shares of the Company’s common stock, par value of $0.001 per share, with aggregate gross sales proceeds of up to $ 50.0 million through an “at the market” equity offering program (the “ATM Program”). The Company will pay Piper Sandler a commission of 3.0 % of the gross proceeds of any shares sold. The Company also agreed to reimburse Piper Sandler for certain expenses incurred in connection with its services under the ATM Agreement, including up to $ 50,000 for legal expenses in connection with the establishment of the ATM Program. Sales of shares of common stock under the ATM Program will be made pursuant to the registration statement on Form S-3 (File No. 333-253874), which was declared effective by the SEC on May 3, 2021, and a related prospectus supplement file with the SEC on October 15, 2021. For the year ended December 31, 2021, no shares of common stock were sold under the ATM Program.

Net Loss per Share Attributable

Net Loss per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Net Loss per Share Attributable to Common Stockholders	15. Net Loss per Share Attributable to Common Stockholders Since the Company was in a loss position for all periods presented, diluted net loss per share is the same as basic net loss per share for all periods as the inclusion of all potential common shares outstanding would have been anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: Year Ended December 31, 2021 2020 Options to purchase common stock 2,603,630 2,355,615 Common stock warrants 85 85 Total 2,603,715 2,355,700

Restructuring

Restructuring	12 Months Ended
	Dec. 31, 2021
Restructuring And Related Activities [Abstract]
Restructuring	16. Restructuring In November 2021, the Board approved a restructuring of its business based on its decision to stop the clinical development of MarzAA and focus solely on its complement programs and protease medicines platform. The restructuring included a reduction-in-force whereby approximately 35% of employees were terminated. During the year ended December 31, 2021, the Company recorded charges of $0.4 million related to one-time severance costs and related expenses in connection with the workforce reduction, and charges of $3.8 million related to the write-off of prepaid manufacturing costs that will no longer be used for the clinical development of MarzAA. As of December 31, 2021, the remaining restructuring liability was $0.2 million, which the Company expects to pay in the first quarter of 2022. The following table summarizes restructuring charges recorded in each component of operating expenses in the Company’s consolidated statements of operations (in thousands): Year Ended December 31, 2021 Research and development $ 4,025 General and administrative 143 Total restructuring charges $ 4,168

Subsequent Event

Subsequent Event	12 Months Ended
	Dec. 31, 2021
Subsequent Events [Abstract]
Subsequent Event	1 7 . Subsequent Event Biogen Agreement In March 2022, the Company received written notice that Biogn is terminating the Biogen Agreement. Pursuant to the terms of the Biogen Agreement, termination will be effective in May 2022 Sublease Agreement In March 2022, the Company entered into a sublease agreement for one of its leased facilities that commences in April 2022. Under the terms of the sublease agreement, the Company will receive $0.2 million in base lease payments over the term of the sublease, which ends in April 2023 Advisor Agreement In March 2022, the Company entered into a financial advisor agreement with Raymond James & Associates, Inc. (“Raymond James”) to help the Company evaluate the possible sale or merger of the Company with various third-parties. Raymond James will be paid an advisory fee of up to $1.0 million upon the effective sale or merger of the Company and will be reimbursed up to $20,000 for reasonable legal, travel and out-of-pocket expenses. Other Event In March 2022, the Company announced that it intends to further reduce its workforce as part of its restructuring plan. Under the restructuring plan, the Company will provide employees one-time severance payments upon termination, continued benefits for a specific period, and outplacement services. The Company expects to incur total expenses of approximately $0.8 million, which is expected to be paid out during the second quarter of 2022.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements include the accounts of the Company and its subsidiary. Intercompany accounts and transactions, if applicable, have been eliminated in consolidation. The Company’s consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”).
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, allowance of doubtful accounts, operating lease right-of-use assets and liabilities, accrued expenses, income taxes and stock-based compensation. The Company bases its estimates on various assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Accounting Pronouncements Recently Adopted	Accounting Pronouncements Recently Adopted In December 2019, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The adoption of ASU 2019-12 did not have a material impact on the Company’s consolidated financial statements. New Accounting Pronouncements – Issued But Not Yet Adopted In June 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instruments In May 2021, the FASB issued ASU 2021-04, Earnings Per Share (Topic 260), Debt—Modifications and Extinguishments (Subtopic 470-50), Compensation—Stock Compensation (Topic 718), and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Issuer’s Accounting for Certain Modifications or Exchanges of Freestanding Equity-Classified Written Call Options
Cash and Cash Equivalents	Cash and Cash Equivalents The Company invests its excess cash in bank deposits, consisting primarily of money market mutual funds. The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the consolidated financial statements on a recurring basis. 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 fair value hierarchy requires that an entity maximize the use of observable inputs when estimating fair value. The fair value hierarchy includes the following three-level classification which is based on the market observability of the inputs used for estimating the fair value of the assets or liabilities being measured: Level 1 – Quoted prices in active markets for identical assets or liabilities. Level 2 – Observable inputs other than quoted prices in active markets for identical assets and liabilities, quoted prices for identical or similar assets or liabilities in inactive markets, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 – Inputs that are generally unobservable and typically reflect management’s estimate of assumptions that market participants would use in pricing the asset or liability.
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets, which are three years for computer equipment and software, and three to seven years for furniture and leasehold improvements.
Investments	Investments The Company invests its excess cash in investment grade, short to intermediate-term, fixed income securities and recognizes purchased securities on the settlement date. All investments have been classified as “available-for-sale” and are carried at estimated fair value based upon quoted market prices or pricing models for similar securities. Management determines the appropriate classification of its investments at the time of purchase and reevaluates such designation as of each consolidated balance sheet date. Unrealized gains and losses on available-for-sale debt securities are excluded from earnings and are reported as a component of comprehensive loss. Realized gains and losses and declines in fair value determined to be other-than-temporary, if any, on available-for-sale debt securities are included in interest and other income (expense), net. The cost of securities sold is based on the specific-identification method. Interest on short-term investments is included in interest and other income (expense), net.
Revenue Recognition	Revenue Recognition License and Collaboration Arrangements The Company may enter into collaboration arrangements that fall under the scope Collaborative Arrangements (Topic 808). The Company analyzes its collaboration arrangements to assess whether they are within the scope of ASC 808 to determine whether such arrangements involve joint operating activities performed by parties that are both active participants in the activities and exposed to significant risks and rewards dependent on the commercial success of such activities. This assessment is performed throughout the life of the arrangement based on changes in the responsibilities of all parties in the arrangement. The accounting for some of the activities under collaboration arrangements may be analogized to ASC 606 for distinct units of account that are reflective of a vendor-customer relationship. Under ASC 606, in determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when the Company satisfies each performance obligation. If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues attributed to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgement to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time. At the inception of each arrangement that contain development milestones, the Company evaluates whether the development milestones included are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not generally considered probable of being achieved until those approvals are received. At the end of each reporting period, the Company re-evaluates the probability of achievement of any development milestones, and if necessary, adjusts its estimate of the transaction price. Any such adjustments would be recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. For research and development services, the Company elected the practical expedient to recognize revenue as the research and development services are invoiced. As the Company has a right to consideration from the collaboration agreement with Biogen International GmbH (“Biogen”), in an amount that corresponds directly with the value of the Company’s performance completed to date for the research services, the Company recognized revenue related to the research services as invoiced, in line with the practical expedient in ASC 606-10-55-18. The transaction price is allocated to each performance obligation on a relative stand-alone selling price (“SSP”) basis. The Company recognizes revenue as or when the performance obligations under the contract are satisfied. As part of the accounting for these arrangements, the Company must develop assumptions that require judgment to determine the timing of recognition and the SSP for each performance obligation identified in the contract. The SSP for licenses are calculated using the residual approach if the Company has not yet established a price for such license and the license has not previously been sold on a standalone basis. Otherwise, selling prices for licenses are determined using an income approach model and include key assumptions such as: development timeline, revenue forecast, commercialization expenses, discount rate and probabilities of technical and regulatory success. To estimate the SSP for research and development services, the Company uses a cost-plus margin approach.
Cost of License and Collaboration Revenue	Cost of License and Collaboration Cost of license revenue includes sublicense fees paid or payable to Mosaic Biosciences, Inc. (“Mosaic”), incurred in the period, under the terms of the Mosaic collaboration agreement, and fees for patent development and protection paid or payable to other third-party vendors corresponding to the recognition of license revenue from the Company’s collaboration agreement with Biogen. See Notes 8 and 12, Related Parties and Collaborations, respectively. Cost of license revenue does not include any allocated overhead costs. Cost of collaboration revenue includes fees for research and development services paid or payable to Mosaic and other third-party vendors and personnel cost, incurred in the period pertaining to the Company’s agreement with Biogen. See Notes 8 and 12, Related Parties and Collaborations, respectively. Cost of collaboration revenue does not include any allocated overhead costs.
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred. Nonrefundable advance payments for goods or services used in research and development are initially deferred and capitalized in prepaid and other current assets. The capitalized amounts are then expensed as the related goods are delivered or services are performed, or until it is no longer expected that the goods or services will be delivered. Research and development costs consist of payroll and other personnel-related expenses, laboratory supplies and reagents, contract research and development services, materials, and consulting costs, as well as allocations of facilities and other overhead costs. Under the Company’s collaboration agreement with Biogen, certain specific expenditures are reimbursed by third parties. During the years ended December 31, 2021 and 2020, $6.5 million and $5.4 million, respectively, of research and development expense was recorded as cost of collaboration revenue related to the collaboration agreement with Biogen signed in December 2019.
Accrued Research and Development Expenses	Accrued Research and Development Expenses Accrued expenses include estimated costs of research and development activities conducted by external service providers, which include the conduct of preclinical studies and clinical trials 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 other accrued liabilities in the consolidated balance sheet and within research and development expense in the consolidated statement of operations. These costs are a significant component of the research and development expenses. The Company records accrued expenses for these costs based on the estimated amount of work completed and in accordance with agreements established with these external service providers.
Concentration Risk Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist principally of cash, cash equivalents, investments and accounts receivable. The Company’s investment policy restricts cash investments to high credit quality, investment grade investments. The Company believes that it has established guidelines for investment of its excess cash that maintain safety and liquidity through its policies on high quality of investment and investment duration. The Company is exposed to credit risk in the event of default by the institutions holding the cash and cash equivalents to the extent beyond the amount insured by the federal depository insurance corporation. The Company’s accounts receivable as of December 31, 2021 of $1.8 million as well as its total license and collaboration revenue of $7.3 million and $20.9 million for the years ended December 31, 2021 and 2020, respectively, are from one party, see Note 12, Collaborations
Accounts Receivable, net and Allowance for Doubtful Accounts	Accounts Receivable and Allowance for Doubtful Accounts Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional. Customer payments are recorded as deferred revenue upon receipt or when due and may require deferral of revenue recognition to a future period until the Company performs its obligations under the arrangements. The Company continuously monitors collections and payments from its customers and maintains a provision for estimated credit losses. The Company determines its allowance for doubtful accounts by considering a number of factors, including the length of time balances are past due, the Company’s previous loss history, the customer’s current ability to pay its obligations to the Company and the condition of the general economy and the industry as a whole. The Company writes off accounts receivable when they are determined to be uncollectible. For the years ended December 31, 2021 and 2020, there were no allowance for doubtful accounts deemed necessary.
Income Taxes	Income Taxes Income taxes are computed using the liability method. Deferred tax assets and liabilities are determined based on the differences between the financial reporting and tax basis of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The Company follows the authoritative guidance on accounting for uncertainty in income taxes. This guidance prescribes a more-likely-than-not threshold for financial statement recognition and measurement of a tax position taken in the Company’s income tax returns. This interpretation also provides guidance on accounting for interest and penalties and associated with tax positions, accounting for income taxes in interim periods and income tax disclosures. The Company’s policy is to include penalties and interest expense related to income taxes as a component of other expense and interest expense, respectively, as necessary.
Stock-Based Compensation	Stock-Based Compensation The Company measures the cost of employee, non-employee and director services received in exchange for an award of equity instruments based on the fair value of the award on the date of grant and recognizes the related expense over the period during which the employee, non-employee or director is required to provide service in exchange for the award on a straight-line basis. 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. The Company uses the Black-Scholes option-pricing valuation model to estimate the grant-date fair value of stock-based awards. The determination of fair value for stock-based awards on the date of grant using an option-pricing model requires management to make certain assumptions regarding a number of variables. T he Company elected to account for forfeitures when they occur. As such, the Company recognizes stock-based compensation expense, over their requisite service period, based on the vesting provisions of the individual grants.
Restructuring Charges	Restructuring Charges Costs and liabilities associated with restructuring are recorded in the period management commits to a restructuring or cost reduction plan, or executes specific actions contemplated by the plan and all criteria for liability recognition have been met. One-time employee termination costs are recognized at the time of communication to employees, unless future service is required, in which case the costs are recognized ratably over the future service period. Restructuring charges are recognized as an operating expense within the consolidated statements of operations and related liabilities are recorded within accrued compensation on the consolidated balance sheets. The Company periodically evaluates and, if necessary, adjusts its estimates based on currently available information.
Leases	Leases At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances present. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes its incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. Certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received.
Net Loss per Share	Net Loss per Share Attributable to Common Stockholders Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss of the Company for all periods presented.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables present the fair value hierarchy for assets measured at fair value on a recurring basis as of December 31, 2021 and 2020 (in thousands) December 31, 2021 Level 1 Level 2 Level 3 Total Financial assets: Money market funds ( 1) $ 44,347 $ — $ — $ 44,347 U.S. government agency securities ( 2) 2,504 — — 2,504 Total financial assets $ 46,851 $ — $ — $ 46,851 December 31, 2020 Level 1 Level 2 Level 3 Total Financial assets: Money market funds ( 1) $ 30,360 $ — $ — $ 30,360 U.S. government agency securities ( 2) 37,837 — — 37,837 Federal agency securities ( 2) — 13,700 — 13,700 Total financial assets $ 68,197 $ 13,700 $ — $ 81,897 (1) Included in cash and cash equivalents on accompanying consolidated balance sheet. (2) Included in short-term investments on accompanying consolidated balance sheet and are classified as available-for-sale debt securities. $2.5 million of U.S. government agency securities as of December 31, 2020 are included in long-term investments on the accompanying consolidated balance sheets due to the maturity being more than 12 months. The carrying amounts of cash, accounts receivable, accounts payable and accrued liabilities approximate their fair values due to the short-term maturity of these instruments.

Financial Instruments (Tables)

Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2021
Investments All Other Investments [Abstract]
Cash Equivalents, Restricted Cash and Short-Term Investments Classified as Available-for-sale Securities	Cash equivalents and investments (debt securities) which are classified as available-for-sale securities, consisted of the following (in thousands) December 31, 2021 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds (cash equivalents) $ 44,347 $ — $ — $ 44,347 U.S. government agency securities 2,504 — — 2,504 Total financial assets $ 46,851 $ — $ — $ 46,851 Classified as: Cash and cash equivalents $ 44,347 Short-term investments 2,504 $ 46,851 December 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Fair Value Money market funds (cash equivalents) $ 30,360 $ — $ — $ 30,360 U.S. government agency securities 37,835 2 — 37,837 Federal agency securities 13,697 3 — 13,700 Total financial assets $ 81,892 $ 5 $ — $ 81,897 Classified as: Cash and cash equivalents $ 30,360 Short-term investments 48,994 Long-term investments 2,543 $ 81,897

Other Accrued Liabilities (Tabl

Other Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2021
Payables And Accruals [Abstract]
Schedule of Other Accrued Liabilities	Other accrued liabilities consisted of the following (in thousands) Year Ended December 31, 2021 2020 Manufacturing $ 1,381 $ 2,238 Biogen 868 — Pre-clinical 773 — Professional and consulting services 509 3,979 Clinical 361 291 Other 180 235 Total other accrued liabilities $ 4,072 $ 6,743

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Lessee Disclosure [Abstract]
Summary of Present Value Assumptions used in Calculating Present Value of Lease Payments	The present value assumptions used in calculating the present value of the lease payments were as follows: December 31, 2021 2020 Weighted-average remaining lease term 1.3 years 2.3 years Weighted-average discount rate 4.8 % 5.7 %
Schedule of Maturity of Operating Lease Liabilities	The maturity of the Company’s operating lease liabilities as of December 31, 2021 were as follows (in thousands): Year Ending December 31, Amount 2022 $ 2,044 2023 410 Total undiscounted lease payments 2,454 Less: imputed interest (69 ) Total operating lease liability $ 2,385
Schedule of Supplemental Cash Flow Information	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. The Company did not incur significant variable lease costs for the years ended December 31, 2021 and 2020. Supplemental cash flow information related to operating leases was as follows (in thousands) Year Ended December 31, 2021 2020 Cash paid for amounts included in the measurement of lease liabilities $ 1,641 $ 602 Prepaid cash payment for lease 208 — Cash paid for operating leases that were included in operating cash outflows $ 1,849 $ 602

Stock Based Compensation (Table

Stock Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Option Activity Under Company's Equity Incentive Plans	The following table summarizes stock option activity under the Company’s 2018 Plan and related information: Number of Shares Underlying Outstanding Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (thousands) Outstanding — December 31, 2019 1,577,541 $ 10.85 8.15 $ 1,350 Options granted 1,091,250 6.26 Options exercised (44,605 ) 5.04 Options forfeited (250,641 ) 10.32 Options expired (17,930 ) 51.12 Outstanding — December 31, 2020 2,355,615 $ 8.59 7.96 $ 1,337 Options granted 1,493,238 5.31 Options exercised (5,000 ) 4.63 Options forfeited (1,239,630 ) 6.26 Options expired (593 ) 566.33 Outstanding — December 31, 2021 2,603,630 $ 7.70 7.46 $ — Exercisable — December 31, 2021 1,513,039 $ 9.37 6.35 $ — Shares available to be granted — December 31, 2021 3,333,791
Summary of Weighted Average Valuation Assumptions Used to Estimate Fair Value of Employee Stock Options	The fair value of employee stock options was estimated using the following weighted-average assumptions: Year Ended December 31, 2021 2020 Employee Stock Options: Expected term (in years) 6.00 5.81 Risk-free interest rate 0.84 % 0.91 % Dividend yield — — Volatility 93.25 % 113.36 %
Summary of Stock-Based Compensation Recognized	Total stock-based compensation recognized was as follows (in thousands): Year Ended December 31, 2021 2020 Research and development $ 1,202 $ 1,487 General and administrative (1) 2,203 2,140 Total stock-based compensation $ 3,405 $ 3,627 (1) Included in general and administrative stock-based compensation for the years ended December 31, 2021 and 2020 is $0.3 million and $0.3 million in expense related to 56,912 shares and 51,056 shares of common stock, respectively, issued to certain board members in lieu of their cash compensation.

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Reconciliation of Federal Income Tax Rate to Company's Effective Tax Rate	The reconciliation of the federal statutory income tax rate to the Company’s effective tax rate for the years ended December 31, 2021 and 2020 are as follows: Year Ended December 31, 2021 2020 Tax at statutory federal rate -21.00 % -21.00 % State Tax (benefit)—net of federal benefit 0.00 % 0.00 % Permanent differences 0.35 % 0.58 % Tax credits -5.86 % -12.26 % Derecognition due to Sec. 382 and 383 limitations 0.00 % 44.55 % Change in valuation allowance 26.26 % -12.25 % Other 0.25 % 0.38 % Effective tax rate 0.00 % 0.00 %
Components of the Company's Deferred Tax Assets (Liabilities)	Significant components of the Company’s deferred tax assets as of December 31, 2021 and 2020 consist of the following (in thousands): Year Ended December 31, 2021 2020 Deferred tax assets: Accruals and reserves $ 1,000 $ 1,095 Net operating loss carry forwards 47,541 29,505 Tax credit carry forwards 12,939 7,789 Fixed and intangible assets 3 7 Valuation allowance (61,483 ) (38,396 ) Net deferred tax assets: $ — $ —
Unrecognized Tax Benefits	A reconciliation of the beginning and ending balance of the unrecognized tax benefits is as follows (in thousands) Beginning Balance at January 1, 2020 $ 1,871 Increase/(Decrease) of unrecognized tax benefits taken in prior years (295 ) Increase/(Decrease) of unrecognized tax benefits related to current year 1,379 Ending Balance at December 31, 2020 $ 2,955 Increase/(Decrease) of unrecognized tax benefits taken in prior years — Increase/(Decrease) of unrecognized tax benefits related to current year 1,749 Ending Balance at December 31, 2021 $ 4,704

Interest and Other Income (Ex_2

Interest and Other Income (Expense), Net (Tables)	12 Months Ended
	Dec. 31, 2021
Other Income And Expenses [Abstract]
Detail of Interest and Other Income (Expense), Net	The following table shows the detail of interest and other income (expense), net as follows (in thousands): Year Ended December 31, 2021 2020 Interest income $ 39 $ 561 Miscellaneous income 9 659 Other (87 ) (91 ) Total interest and other income (expense), net $ (39 ) $ 1,129

Net Loss per Share Attributab_2

Net Loss per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Anti-dilutive Security not Included in Diluted per Share Calculations	Since the Company was in a loss position for all periods presented, diluted net loss per share is the same as basic net loss per share for all periods as the inclusion of all potential common shares outstanding would have been anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows: Year Ended December 31, 2021 2020 Options to purchase common stock 2,603,630 2,355,615 Common stock warrants 85 85 Total 2,603,715 2,355,700

Restructuring (Tables)

Restructuring (Tables)	12 Months Ended
	Dec. 31, 2021
Restructuring And Related Activities [Abstract]
Summary of Restructuring Charges Recorded in Component of Operating Expenses	The following table summarizes restructuring charges recorded in each component of operating expenses in the Company’s consolidated statements of operations (in thousands): Year Ended December 31, 2021 Research and development $ 4,025 General and administrative 143 Total restructuring charges $ 4,168

Nature of Operations - Addition

Nature of Operations - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021Segment
Accounting Policies [Abstract]
Number of operating segment	1

Liquidity - Additional Informat

Liquidity - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Liquidity [Abstract]
Accumulated deficit	$ 402,694	$ 314,761
Cash, cash equivalents and short-term investments	46,900
Net loss	$ 87,933	$ 56,241

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Summary Of Significant Accounting Policies [Line Items]
Accounts receivable	$ 1,800
License and collaboration revenue	7,338	$ 20,948
Research and Development Expense
Summary Of Significant Accounting Policies [Line Items]
Cost of collaboration revenue	$ 6,500	$ 5,400
Software
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Computer equipment
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Furniture | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Furniture | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	7 years
Leasehold improvements | Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Leasehold improvements | Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	7 years

Assets and Liabilities Measured

Assets and Liabilities Measured at Fair Value - Additional Information (Detail) $ in Millions	Dec. 31, 2021USD ($)
Long Term Investments | U.S. Government Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale, debt securities	$ 2.5

Assets and Liabilities Measur_2

Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands		Dec. 31, 2021	Dec. 31, 2020
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets, fair value		$ 46,851	$ 81,897
Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets, fair value	[1]	44,347	30,360
Fair Value, Inputs, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets, fair value		46,851	68,197
Fair Value, Inputs, Level 1 | Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets, fair value	[1]	44,347	30,360
Fair Value, Inputs, Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets, fair value			13,700
U.S. Government Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets, fair value	[2]	2,504	37,837
U.S. Government Agency Securities | Fair Value, Inputs, Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets, fair value	[2]	$ 2,504	37,837
Short-Term Investments | Federal Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets, fair value	[2]		13,700
Short-Term Investments | Fair Value, Inputs, Level 2 | Federal Agency Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets, fair value	[2]		$ 13,700
[1]	Included in cash and cash equivalents on accompanying consolidated balance sheet.
[2]	Included in short-term investments on accompanying consolidated balance sheet and are classified as available-for-sale debt securities. $2.5 million of U.S. government agency securities as of December 31, 2020 are included in long-term investments on the accompanying consolidated balance sheets due to the maturity being more than 12 months.

Cash Equivalents, Restricted Ca

Cash Equivalents, Restricted Cash and Short-Term Investments Classified as Available-for-sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 46,851	$ 81,892
Gross Unrealized Gains		5
Estimated Fair Value	46,851	81,897
Federal Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		13,697
Gross Unrealized Gains		3
Estimated Fair Value		13,700
Money Market Funds | Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	44,347	30,360
Estimated Fair Value	44,347	30,360
U.S. Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	2,504	37,835
Gross Unrealized Gains		2
Estimated Fair Value	2,504	37,837
Cash and Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	44,347	30,360
Short-Term Investments
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value	$ 2,504	48,994
Other Long-term Investments
Schedule Of Available For Sale Securities [Line Items]
Estimated Fair Value		$ 2,543

Financial Instruments - Additio

Financial Instruments - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2021USD ($)
Financial Instrument [Line Items]
Material realized gains or losses on available-for-sale securities	$ 0
Available-for-sale debt securities current	$ 2,500,000
Maximum
Financial Instrument [Line Items]
Available for sale debt securities contractual maturities	1 year

Schedule of Other Accrued Liabi

Schedule of Other Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Manufacturing	$ 1,381	$ 2,238
Biogen	868
Pre-clinical	773
Professional and consulting services	509	3,979
Clinical	361	291
Other	180	235
Total other accrued liabilities	$ 4,072	$ 6,743

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2021	Dec. 31, 2021
Commitments And Contingencies Disclosure [Line Items]
Charges related to write off of prepaid manufacturing cost	$ 3.8	$ 3.8
AGC Biologics, Inc | Marzeptacog Alfa Activated and Dalcinonacog Alfa
Commitments And Contingencies Disclosure [Line Items]
Firm work order supporting clinical trials		15.8
AGC Biologics, Inc | Marzeptacog Alfa Activated and Dalcinonacog Alfa | Service Agreements
Commitments And Contingencies Disclosure [Line Items]
Cost of Manufacturing Services		0.7
Contractual obligation payments		0.3
Marzeptacog Alfa Activated | Marzeptacog Alfa Activated and Dalcinonacog Alfa | Maximum | Service Agreements
Commitments And Contingencies Disclosure [Line Items]
Cost of services as per agreement		3.2
Marzeptacog Alfa Activated | Dalcinonacog Alfa | Maximum | Service Agreements
Commitments And Contingencies Disclosure [Line Items]
Cost of services as per agreement		6.5
Catalent Indiana, LLC. | Dalcinonacog alfa.
Commitments And Contingencies Disclosure [Line Items]
Firm work order supporting clinical trials		$ 0.2

Related Parties - Additional In

Related Parties - Additional Information (Detail) - Mosaic Biosciences Inc - USD ($) $ in Millions	May 08, 2020	Dec. 31, 2020	Jan. 10, 2020
Related Party Transaction [Line Items]
One Time Expense related to collaboration	$ 0.8
Maximum
Related Party Transaction [Line Items]
Milestone Payment Related To Regulatory And Clinical Development Events	$ 4
Intravitreal Anti-Complement Factor 3
Related Party Transaction [Line Items]
Payment related to collaboration		$ 3
Biogen Collaboration | Intravitreal Anti-Complement Factor 3
Related Party Transaction [Line Items]
Upfront license fee received from collaboration agreement			$ 15

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Thousands	Jul. 17, 2020	Oct. 31, 2021	Apr. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Lessee Lease Description [Line Items]
Lease expiration date				Apr. 30, 2023
Lessee operating lease renewal term description				no stated renewal options
Right-of-use asset and lease liability		$ 600
Undiscounted future payment	$ 500			$ 2,454
Operating lease not yet commenced description	commenced during the fourth quarter of 2020.
Operating lease term of contract	2 years 7 months 6 days
Operating lease expense				$ 1,700	$ 700
Lease Lab And Office Space | Sublease Arrangement
Lessee Lease Description [Line Items]
Undiscounted future payment			$ 1,900
Operating lease, option to extend			This License Agreement has an original lease term of one year and a renewal period of six months
Operating lease commenced description			commenced during the second quarter of 2021

Summary of Present Value Assump

Summary of Present Value Assumptions used in Calculating Present Value of Lease Payments (Detail)	Dec. 31, 2021	Dec. 31, 2020
Lessee Disclosure [Abstract]
Weighted-average remaining lease term	1 year 3 months 18 days	2 years 3 months 18 days
Weighted-average discount rate	4.80%	5.70%

Schedule of Maturity of Operati

Schedule of Maturity of Operating Lease Liabilities - (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Jul. 17, 2020
Operating Lease Liabilities Payments Due [Abstract]
2022	$ 2,044
2023	410
Total undiscounted lease payments	2,454	$ 500
Less: imputed interest	(69)
Total operating lease liability	$ 2,385

Schedule of Supplemental Cash F

Schedule of Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating Lease Liabilities Payments Due [Abstract]
Cash paid for amounts included in the measurement of lease liabilities	$ 1,641	$ 602
Prepaid cash payment for lease	208
Cash paid for operating leases that were included in operating cash outflows	$ 1,849	$ 602

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Detail) - USD ($)	Jun. 09, 2021	Jun. 13, 2018	Dec. 31, 2021	Dec. 31, 2020	Feb. 28, 2021
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Weighted average grant date fair value of stock options			$ 4	$ 5.20
Aggregate intrinsic value of options exercised			$ 3,000	$ 100,000
Fair value of options vested			$ 2,600,000	3,000,000
Number of common stock available for future grant			3,333,791
Total stock-based compensation			$ 3,405,000	3,627,000
Employee Stock Option
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Unrecognized employee stock based compensation expense			$ 3,900,000
Unrecognized employee stock based compensation expense, period for recognition			2 years 5 months 26 days
2018 Omnibus Incentive Plan
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Increase in number of shares of common stock reserved for issuance	2,500,000
Common Stock, Capital Shares Reserved for Future Issuance	5,300,000
2018 Omnibus Incentive Plan | Performance Based Stock Option Grants
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Issuance of option grants to purchase common stock shares					647,000
2018 Employee Stock Purchase Plan
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Maximum employee subscription rate		15.00%
Number of common stock available for future grant			235,469
Number of common stock authorized for issuance			359,545
Number of common stock stock issued			64,975
Proceeds from Issuance			$ 300,000
Total stock-based compensation			$ 100,000	$ 100,000
2018 Employee Stock Purchase Plan | Maximum
Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table]
Percentage of fair market value of common stock		85.00%

Summary of Option Activity Unde

Summary of Option Activity Under Company's Equity Incentive Plans (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Number of Shares Underlying Outstanding Options
Number of Shares Underlying Outstanding Options, Beginning Balance	2,355,615	1,577,541
Number of Shares Underlying Outstanding Options, Options granted	1,493,238	1,091,250
Number of Shares Underlying Outstanding Options, Options exercised	(5,000)	(44,605)
Number of Shares Underlying Outstanding Options, Options forfeited	(1,239,630)	(250,641)
Number of Shares Underlying Outstanding Options, Options expired	(593)	(17,930)
Number of Shares Underlying Outstanding Options, Ending Balance	2,603,630	2,355,615	1,577,541
Number of Shares Underlying Outstanding Options, Exercisable- December 31, 2020	1,513,039
Shares available to be granted - December 31, 2020	3,333,791
Weighted- Average Exercise Price
Weighted- Average Exercise Price, Beginning Balance	$ 8.59	$ 10.85
Weighted- Average Exercise Price, Options granted	5.31	6.26
Weighted- Average Exercise Price, Options exercised	4.63	5.04
Weighted- Average Exercise Price, Options forfeited	6.26	10.32
Weighted- Average Exercise Price, Options expired	566.33	51.12
Weighted- Average Exercise Price, Ending Balance	7.70	$ 8.59	$ 10.85
Weighted- Average Exercise Price, Exercisable - December 31, 2020	$ 9.37
Weighted-Average Remaining Contractual Term (Years)
Weighted-Average Remaining Contractual Term (Years), Outstanding Balance	7 years 5 months 15 days	7 years 11 months 15 days	8 years 1 month 24 days
Weighted Average Remaining Contractual Term, Exercisable - December 31, 2020	6 years 4 months 6 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value, Outstanding		$ 1,337	$ 1,350

Fair Values of Stock Options Es

Fair Values of Stock Options Estimated Using Black-Scholes Valuation Model (Detail) - Employee Stock Option	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Black Scholes Method Used [Line Items]
Expected term (in years)	6 years	5 years 9 months 21 days
Risk-free interest rate	0.84%	0.91%
Dividend yield	0.00%	0.00%
Volatility	93.25%	113.36%

Summary of Stock-Based Compensa

Summary of Stock-Based Compensation Recognized (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation		$ 3,405	$ 3,627
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation		1,202	1,487
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	[1]	$ 2,203	$ 2,140
[1]	Included in general and administrative stock-based compensation for the years ended December 31, 2021 and 2020 is $0.3 million and $0.3 million in expense related to 56,912 shares and 51,056 shares of common stock, respectively, issued to certain board members in lieu of their cash compensation.

Summary of Stock-Based Compen_2

Summary of Stock-Based Compensation Recognized (Parenthetical) (Detail) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Number of shares of common stock issued to certain board members in lieu of cash compensation		56,912	51,056
Total stock-based compensation		$ 3,405	$ 3,627
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation	[1]	2,203	2,140
General and Administrative | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total stock-based compensation		$ 300	$ 300
[1]	Included in general and administrative stock-based compensation for the years ended December 31, 2021 and 2020 is $0.3 million and $0.3 million in expense related to 56,912 shares and 51,056 shares of common stock, respectively, issued to certain board members in lieu of their cash compensation.

Reconciliation of Statutory Fed

Reconciliation of Statutory Federal Income Tax (benefit) Rate to Company's Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Tax at statutory federal rate	(21.00%)	(21.00%)
State Tax (benefit)—net of federal benefit	(0.00%)	(0.00%)
Permanent differences	0.35%	0.58%
Tax credits	(5.86%)	(12.26%)
Derecognition due to Sec. 382 and 383 limitations	(0.00%)	44.55%
Change in valuation allowance	26.26%	(12.25%)
Other	0.25%	0.38%
Effective tax rate	0.00%	0.00%

Components of the Company's Def

Components of the Company's Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Accruals and reserves	$ 1,000	$ 1,095
Net operating loss carry forwards	47,541	29,505
Tax credit carry forwards	12,939	7,789
Fixed and intangible assets	3	7
Valuation allowance	$ (61,483)	$ (38,396)

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	Jun. 29, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2007
Income Tax [Line Items]
Increase (decrease) in valuation allowance		$ (23,100,000)	$ 6,900,000
Gross federal R&D tax credit-related deferred tax assets derecognized		15,200,000
Unrecognized tax benefit		4,704,000	2,955,000	$ 1,871,000
Tax-related penalties or interest recognized		0	0
Uncertain tax positions		0	$ 0
Federal Income Tax
Income Tax [Line Items]
Net operating loss carryforwards		$ 226,400,000			$ 156,300,000
Net operating loss carryforwards expiration year		2037
Net operating loss carryforwards having indefinite life		$ 218,900,000
Tax credit carryforwards available to offset future federal tax liabilities		11,400,000
Credit carryforward, expire period			Dec. 31, 2040
Net operating loss carryforward, derecognized		32,800,000
State Income Tax
Income Tax [Line Items]
Net operating loss carryforwards		$ 8,000,000
Net operating loss carryforwards expiration year		2032
Tax credit carryforwards available to offset future federal tax liabilities		$ 7,500,000
CALIFORNIA
Income Tax [Line Items]
Net operating loss carryforwards		70,800,000
Net operating loss carryforward, derecognized		$ 0
Maximum amount of tax offset per year	$ 5,000,000
Required Minimum Taxable Income	$ 1,000,000

Unrecognized tax benefit (Detai

Unrecognized tax benefit (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Beginning Balance	$ 2,955	$ 1,871
Increase/(Decrease) of unrecognized tax benefits taken in prior years		(295)
Increase/(Decrease) of unrecognized tax benefits related to current year	1,749	1,379
Ending Balance	$ 4,704	$ 2,955

Collaborations - Additional Inf

Collaborations - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 18, 2019	Jan. 31, 2020	Dec. 31, 2018	Dec. 31, 2021	Dec. 31, 2020
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue				$ 7,338	$ 20,948
Deferred revenue, recognized				2,000
License
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue					15,100
License | Transfer of Exclusive License and Related Know-How
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue					15,000
Exclusive License
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue					100
Collaboration
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue				7,338	5,848
Collaboration | Reimbursable Out-of-Pocket and Personnel Costs Incurred Related to Research Services
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue				7,300	$ 5,800
ISU Abxis | Amended and Restated License Agreement
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Regulatory and development milestone payment			$ 2,500	0
ISU Abxis | Amended and Restated License Agreement | Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Milestone payment			19,500	0
Commercial milestone payments			$ 17,000	0
Biogen
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
License and collaboration revenue				$ 0
Biogen | License and Collaboration Agreement (the “Biogen Agreement”)
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Research services	30 months
Research services option to extend	12 months
Biogen | Exclusive License
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Up-front payments received		$ 15,000
Biogen | Exclusive License | Maximum
Revenue Recognition Multiple Deliverable Arrangements [Line Items]
Development and sales milestone payments		$ 340,000

Detail of Interest and Other In

Detail of Interest and Other Income (Expense), Net (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Other Income And Expenses [Abstract]
Interest income	$ 39	$ 561
Miscellaneous income	9	659
Other	(87)	(91)
Total interest and other income (expense), net	$ (39)	$ 1,129

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	Oct. 15, 2021	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Stockholders Equity Disclosure [Line Items]
Underwriting discounts, commissions and offering expenses payable		$ 3,600,000
Net proceeds from sale of common stock after deducting underwriting commissions and offering expenses		$ 49,300,000
Common stock warrants issued			31,409,707	22,097,820
Common stock warrants outstanding			31,409,707	22,097,820
Common stock, par value			$ 0.001	$ 0.001
2021 ATM Program
Stockholders Equity Disclosure [Line Items]
Common stock, par value	$ 0.001
Proceeds from Issuance	$ 50,000,000
Percentage of commission for shares sold	3.00%
Legal expenses incurred	$ 50,000
Common Stock
Stockholders Equity Disclosure [Line Items]
Issuance of common stock for public offering, net of issuance costs, shares		9,185,000	9,185,000	9,923,076
Common stock price, per share		$ 5.75
Common Stock | Underwriters' Overallotment Option
Stockholders Equity Disclosure [Line Items]
Issuance of common stock for public offering, net of issuance costs, shares		485,000
Warrants
Stockholders Equity Disclosure [Line Items]
Common stock warrants issued			85	85
Common stock warrants outstanding			85	85
Warrants exercise price per share			$ 392.70	$ 392.70
Warrant expiration date			Aug. 31, 2022

Anti-dilutive Security not Incl

Anti-dilutive Security not Included In Diluted per Share Calculations (Detail) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	2,603,715	2,355,700
Options To Purchase Common Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	2,603,630	2,355,615
Common Stock Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti dilutive securities	85	85

Restructuring - Additional Info

Restructuring - Additional Information (Detail) - USD ($) $ in Millions	Nov. 30, 2021	Nov. 30, 2021	Dec. 31, 2021
Restructuring And Related Activities [Abstract]
Percent of employees terminated	35.00%
Severance costs and expenses			$ 0.4
Charges related to write off of prepaid manufacturing cost		$ 3.8	3.8
Restructuring liability			$ 0.2

Restructuring - Summary of Rest

Restructuring - Summary of Restructuring Charges Recorded in Component of Operating Expenses (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Restructuring Cost And Reserve [Line Items]
Research and development	$ 68,889	$ 52,975
General and administrative	18,963	$ 16,180
Total restructuring charges	4,168
Research and Development Expense
Restructuring Cost And Reserve [Line Items]
Research and development	4,025
General and Administrative
Restructuring Cost And Reserve [Line Items]
General and administrative	$ 143

Subsequent Event - Additional I

Subsequent Event - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Subsequent Event [Line Items]
Lease expiration date		Apr. 30, 2023
Total expenses		$ 4,168,000
Subsequent Event
Subsequent Event [Line Items]
Total expenses	$ 800,000
Subsequent Event | Sublease Arrangement
Subsequent Event [Line Items]
Lease Payments Receivable	$ 200,000
Lease expiration date	Apr. 30, 2023
Subsequent Event | Biogen Agreement
Subsequent Event [Line Items]
Lease expiration date	May 31, 2022
Subsequent Event | Advisor Agreement | Raymond James & Associates
Subsequent Event [Line Items]
Advisory fees payable	$ 1,000,000
Subsequent Event | Advisor Agreement | Raymond James & Associates | Maximum
Subsequent Event [Line Items]
Reimbursement of advisory fee	$ 20,000