Annexon (ANNX) 10-Q 9 May 22 2022 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2022	May 02, 2022
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Amendment Flag	false
Document Period End Date	Mar. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Trading Symbol	ANNX
Entity Registrant Name	ANNEXON, INC.
Entity Central Index Key	0001528115
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Title of 12(b) Security	Common Stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Entity File Number	001-39402
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-5414423
Entity Address, Address Line One	1400 Sierra Point Parkway
Entity Address, Address Line Two	Bldg C
Entity Address, Address Line Three	Suite 200
Entity Address, City or Town	Brisbane
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94005
City Area Code	650
Local Phone Number	822-5500
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		38,563,565

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 112,828	$ 74,843
Short-term investments	93,831	167,872
Prepaid expenses and other current assets	4,595	4,978
Total current assets	211,254	247,693
Restricted cash	1,166	1,166
Property and equipment, net	17,805	17,848
Operating lease right-of-use assets	20,103	20,333
Other non-current assets	241
Total assets	250,569	287,040
Current liabilities:
Accounts payable	9,378	11,153
Accrued liabilities	6,211	9,250
Operating lease liabilities, current	1,275	1,202
Other current liabilities	189	139
Total current liabilities	17,053	21,744
Operating lease liabilities, non-current	32,902	33,387
Total liabilities	49,955	55,131
Commitments and contingencies (Note 5)
Stockholders’ equity:
Common stock	39	39
Additional paid-in capital	532,636	528,365
Accumulated other comprehensive loss	(373)	(180)
Accumulated deficit	(331,688)	(296,315)
Total stockholders’ equity	200,614	231,909
Total liabilities and stockholders’ equity	$ 250,569	$ 287,040

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses:
Research and development	$ 26,998	$ 20,696
General and administrative	8,428	5,506
Total operating expenses	35,426	26,202
Loss from operations	(35,426)	(26,202)
Interest and other income, net	53	142
Net loss	(35,373)	(26,060)
Net loss attributable to common stockholders	$ (35,373)	$ (26,060)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.92)	$ (0.68)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	38,563,384	38,163,062

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (35,373,000)	$ (26,060,000)
Other comprehensive gain (loss):
Foreign currency translation adjustment	3,000	(1,000)
Unrealized loss on available-for-sale securities	(196,000)	(25,000)
Comprehensive loss	$ (35,566,000)	$ (26,086,000)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($)	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
Beginning Balance, Values at Dec. 31, 2020	$ 344,278,000	$ 38,000	$ 510,309,000	$ (77,000)	$ (165,992,000)
Beginning Balance, Shares at Dec. 31, 2020		38,157,618
Stock-based compensation	2,962,000		2,962,000
Stock option exercises	268,000		268,000
Stock option exercises, Shares		74,930
Foreign currency translation adjustment	(1,000)			(1,000)
Unrealized loss on available-for-sale securities	(25,000)			(25,000)
Net loss	(26,060,000)				(26,060,000)
Ending Balance, Values at Mar. 31, 2021	321,422,000	$ 38,000	513,539,000	(103,000)	(192,052,000)
Ending Balance, Shares at Mar. 31, 2021		38,232,548
Beginning Balance, Values at Dec. 31, 2021	231,909,000	$ 39,000	528,365,000	(180,000)	(296,315,000)
Beginning Balance, Shares at Dec. 31, 2021		38,560,854
Stock-based compensation	4,252,000		4,252,000
Stock option exercises	$ 19,000		19,000
Stock option exercises, Shares	2,711	2,711
Foreign currency translation adjustment	$ 3,000			3,000
Unrealized loss on available-for-sale securities	(196,000)			(196,000)
Net loss	(35,373,000)				(35,373,000)
Ending Balance, Values at Mar. 31, 2022	$ 200,614,000	$ 39,000	$ 532,636,000	$ (373,000)	$ (331,688,000)
Ending Balance, Shares at Mar. 31, 2022		38,563,565

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating activities:
Net loss	$ (35,373)	$ (26,060)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	518	538
Accretion of discount on available-for-sale securities	380	180
Stock-based compensation	4,252	2,962
Reduction in the carrying amount of right-of-use assets	230	136
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	383	(1,063)
Other non-current assets	(241)
Accounts payable	1,785	761
Accrued liabilities	(1,860)	(718)
Operating lease liabilities	(412)	(176)
Other current liabilities	50
Net cash used in operating activities	(30,288)	(23,440)
Investing activities:
Purchases of property and equipment	(5,214)	(32)
Purchases of available-for-sale securities	(5,935)	(42,549)
Proceeds from maturities of available-for-sale securities	79,400	5,000
Net cash provided by (used in) investing activities	68,251	(37,581)
Financing activities:
Proceeds from the exercise common stock options	19	268
Net cash provided by financing activities	19	268
increase (decrease) in cash, cash equivalents and restricted cash	37,982	(60,753)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	3	(1)
Cash, cash equivalents and restricted cash
Beginning of period	76,009	268,565
End of period	113,994	207,811
Supplemental disclosure of cash flow information:
Cash paid for amounts included in the measurement of lease liability	1,135	$ 182
Purchases of property and equipment included in accrued liabilities	$ 801

Organization

Organization	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Organization	1. Organization Annexon, Inc., or the Company, is a clinical-stage biopharmaceutical company pioneering a new class of complement medicines for patients with classical complement-mediated autoimmune, neurodegenerative and ophthalmic disorders. The Company is located in Brisbane, California and was incorporated in Delaware in March 2011. The Company’s wholly-owned subsidiary, Annexon Biosciences Australia Pty Ltd, or the Subsidiary, is a proprietary limited company incorporated in 2016 and domiciled in Australia. The Subsidiary is also engaged in research and development activities in support of its parent company. Liquidity Since inception, the Company has been involved primarily in performing research and development activities, conducting clinical trials, hiring personnel, and raising capital to support and expand these activities. The Company has experienced losses and negative cash flows from operations since its inception and, as of March 31, 2022, had an accumulated deficit of $ 331.7 million and cash and cash equivalents and short-term investments of $ 206.7 million. The Company has historically funded its operations through the issuance of shares of its redeemable convertible preferred stock and common stock. Based on projected activities, management projects that cash on hand is sufficient to support operations for at least the next 12 months following issuance of these condensed consolidated financial statements. Management expects to continue to incur losses and negative cash flows from operations for at least the next several years.

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation and Significant Accounting Policies	2. Basis of Presentation and Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States, or GAAP, and applicable rules and regulations of the SEC regarding interim financial reporting. The condensed consolidated balance sheet as of March 31, 2022, and the condensed consolidated statements of operations, comprehensive loss, changes in stockholders’ equity and cash flows for the three months ended March 31, 2022 and 2021 are unaudited. These unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s consolidated financial position as of March 31, 2022 and its results of operations and cash flows for the three months ended March 31, 2022 and 2021. The financial data and the other financial information contained in these notes to condensed consolidated financial statements related to the three-month periods are also unaudited. The results of operations for the three months ended March 31, 2022 are not necessarily indicative of the results to be expected for the year ending December 31, 2022 or for any other future annual or interim period. The condensed consolidated balance sheet as of December 31, 2021 included herein was derived from the audited financial statements as of that date. These condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021, filed with the SEC on March 1, 2022. In the second quarter of 2021, the Company adopted ASU No. 2016-02, Leases (Topic 842), using the modified retrospective approach as of January 1, 2021. The adoption of Topic 842 as of January 1, 2021 resulted in the recognition of right-of-use assets of $ 0.5 million, corresponding lease liabilities of $ 0.6 million, the derecognition of the deferred rent liability of $ 1.4 million, and the recognition of a liability of $ 1.3 million related to the reallocation of the consideration of the Company’s lease pending the commencement of the second lease component in May 2021 (see Note 5— Commitments and Contingencies ). The adoption resulted in additional $ 54,000 of rent expense for the first quarter of 2021. The Company restated its condensed consolidated statement of operations for the three months ended March 31, 2021 to reflect the adoption of Topic 842 and recorded $ 54,000 to general and administrative expense, resulting in a corresponding increase in total operating expense and net loss. The restatement impacts the net loss presented in the condensed consolidated statement of comprehensive loss, condensed consolidated statement of stockholders’ equity, and condensed consolidated statement of cash flows. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported expenses during the reporting period. On an ongoing basis, management evaluates its estimates, including but not limited to fair value of investments, useful lives for property and equipment, incremental borrowing rate used in lease accounting, stock options, income taxes and certain accruals. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates. Principles of Consolidation The condensed consolidated financial statements include the operations of Annexon, Inc. and its wholly-owned subsidiary and include the results of operations and cash flows of these entities. All intercompany balances and transactions have been eliminated in consolidation. Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid instruments with an original maturity of three months or less at time of purchase to be cash equivalents. Cash equivalents, which includes amounts invested in money market funds, are stated at fair value. Restricted cash as of March 31, 2022 relates to the letters of credit established for the Company’s office leases. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets that sum to the total of the same amounts shown in the condensed consolidated statements of cash flows: March 31, December 31, Cash $ 583 $ 734 Cash equivalents 112,245 74,109 Cash and cash equivalents 112,828 74,843 Restricted cash 1,166 1,166 Cash, cash equivalents and restricted cash $ 113,994 $ 76,009 Short-Term Investments Short-term investments have been classified as available-for-sale and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. The Company determines the appropriate classification of its investments in debt securities at the time of purchase. Available-for-sale securities are classified as current based on their availability for use in current operations. Unrealized gains and losses are excluded from earnings and are reported as a component of other comprehensive loss. The Company periodically evaluates whether declines in fair values of its marketable securities below their book value are other-than-temporary. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss as well as the Company’s ability and intent to hold the marketable security until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or it is more likely than not it will be required to sell any marketable securities before recovery of its amortized cost basis. Impairment assessments are made at the individual security level each reporting period. When the fair value of an available-for- sale security is less than its cost at the balance sheet date, a determination is made as to whether the impairment is other-than-temporary and, if it is other-than-temporary, an impairment loss is recognized in other income, net, equal to the difference between the investment’s amortized cost and fair value at such date. The cost of investments sold is based on the specific-identification method. Interest on marketable securities is included in other income, net. Foreign Currencies The Company’s reporting currency is the U.S. dollar. The functional currency of the Company’s subsidiary located in Australia is the Australian Dollar. Balance sheets prepared in the functional currencies are translated to the reporting currency at exchange rates in effect at the end of the accounting period, except for stockholders’ equity accounts, which are translated at rates in effect when these balances were originally recorded. Revenue and expense accounts are translated using a weighted-average rate during the year. The resulting foreign currency translation adjustments are recorded as a separate component of accumulated other comprehensive loss in the accompanying condensed consolidated balance sheets. Foreign currency translation adjustments for the three months ended March 31, 2022 and 2021 were a $ 3,000 gain and a $ 1,000 loss, respectively. Gains and losses resulting from exchange rate changes on transactions denominated in a currency other than the local currency are included in earnings as incurred. Research and Development Expense Research and development expenses consist primarily of direct and indirect costs incurred for the development of the Company’s product candidates. Direct expenses include (i) preclinical and clinical outside service costs associated with discovery, preclinical and clinical testing of the Company’s product candidates; (ii) professional services agreements with third-party contract organizations, investigative clinical trial sites and consultants that conduct research and development activities on the Company’s behalf; (iii) contract manufacturing costs to produce clinical trial materials; and (iv) laboratory supplies and materials. Indirect expenses include (A) compensation and personnel-related expenses (including stock-based compensation); (B) allocated expenses for facilities and depreciation; and (C) other indirect costs. Research and development costs are expensed as incurred. Payments made to third parties are under agreements that are generally cancelable by the Company. Advance payments for research and development activities are deferred as prepaid expenses. The prepaid amounts are expensed as the related services are performed. The Company estimates preclinical studies and clinical trial expenses based on the services performed pursuant to contracts with research institutions and clinical research organizations that conduct and manage preclinical studies and clinical trials on the Company’s behalf. In accruing service fees, the Company estimates the period over which services will be performed and the level of effort to be expended in each period. These estimates are based on the Company’s communications with the third-party service providers and on information available at each balance sheet date. If the actual timing of the performance of services or the level of effort varies significantly from the estimate, the Company will adjust the accrual accordingly to reflect the best information available at the time of the financial statement issuance. The Company has not experienced any material differences between accrued costs and actual costs incurred since its inception. Stock-Based Compensation The Company accounts for stock-based compensation arrangements with employees, non-employee directors and consultants using a fair value method which requires the recognition of compensation expense for costs related to all stock-based payments, including stock options and restricted stock units, or RSUs. The fair value method requires the Company to estimate the fair value of stock options to employees and non-employee directors on the date of grant using the Black-Scholes option pricing model. The fair value of RSU awards is based on the fair value of the underlying common stock as of the grant date. The Company grants certain employees performance-based stock options. For awards that include performance conditions, no compensation cost is recognized until the performance goals are probable of being met, at which time the cumulative compensation expense from the service inception date would be recognized. Stock-based compensation costs are based on the fair value of the underlying option calculated using the Black-Scholes option pricing model and recognized as expense on a straight-line basis (for all but performance-based awards for which the accelerated method is used) over the requisite service period, which is the vesting period. Determining the appropriate fair value model and related assumptions requires judgment, including estimating the fair value of the underlying common stock, expected term, expected stock price volatility, risk-free interest rate and dividend yield. The Company accounts for forfeitures as they occur. Net Loss Per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive shares of common stock. As the Company was in a loss position for all periods presented, basic net loss per share attributable to common stockholders is the same as diluted net loss per share attributable to common stockholders because the effects of potentially dilutive securities are antidilutive. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents and short-term investments. The Company’s cash and cash equivalents and short-term investments are held by high credit quality financial institutions in the United States. At times, such deposits may be in excess of the Federal Depository Insurance Corporation insured limits. Management believes that the financial institutions are financially sound, and accordingly, minimal credit risk exists with respect to the financial institutions. Recently Adopted Accounting Pronouncements The Company has implemented all new accounting pronouncements that are in effect and that may impact its condensed consolidated financial statements and does not believe that there are any other new pronouncements that have been issued that might have a material impact on its financial position or results of operations. Recently Issued Accounting Pronouncements The Company does not believe that any recently issued effective pronouncements, or pronouncements issued but not yet effective, if adopted, would have a material impact on its financial position or results of operations.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible. The Company determines fair value based on assumptions that market participants would use in pricing an asset or liability in the principal or most advantageous market. When considering market participant assumptions in fair value measurements, the following fair value hierarchy distinguishes between observable and unobservable inputs, which are categorized in one of the following levels: • Level 1 Inputs: Unadjusted quoted prices in active markets for identical assets or liabilities accessible to the reporting entity at the measurement date. • Level 2 Inputs: Other than quoted prices included in Level 1 inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability. • Level 3 Inputs: Unobservable inputs for the asset or liability used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at measurement date. On a recurring basis, the Company measures certain financial assets and liabilities at fair value. The following tables summarize the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): March 31, 2022 Valuation Amortized Gross Gross Aggregate Assets: Cash equivalents: Money market funds Level 1 $ 112,245 $ — $ — $ 112,245 Short-term investments: Commercial paper Level 2 42,917 — ( 77 ) 42,840 Corporate debt Level 2 21,501 — ( 28 ) 21,473 Government bonds Level 2 29,707 — ( 189 ) 29,518 Total assets $ 206,370 $ — $ ( 294 ) $ 206,076 December 31, 2021 Valuation Amortized Gross Gross Aggregate Assets: Cash equivalents: Money market funds Level 1 $ 74,109 $ — $ — $ 74,109 Short-term investments: Commercial paper Level 2 85,352 — ( 27 ) 85,325 Corporate bonds Level 2 48,814 — ( 24 ) 48,790 Government bonds 33,809 — ( 52 ) 33,757 Total assets $ 242,084 $ — $ ( 103 ) $ 241,981 For the three months ended March 31, 2022 and 2021, the Company recognized no material realized gains or losses on financial instruments.

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2022
Disclosure Of Balance Sheet Components [Abstract]
Balance Sheet Components	4. Balance Sheet Components Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following (in thousands): March 31, December 31, Prepaid research and development costs $ 3,267 $ 3,002 Prepaid insurance 744 1,282 Other prepaid expenses 450 231 Other current assets 134 463 Total prepaid expenses and other current assets $ 4,595 $ 4,978 Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): March 31, December 31, Leasehold improvements $ 17,051 $ 16,594 Laboratory equipment 1,348 1,353 Furniture and fixtures 668 649 Computer equipment and software 33 41 Total property and equipment, gross 19,100 18,637 Less: accumulated depreciation ( 1,295 ) ( 789 ) Total property and equipment, net $ 17,805 $ 17,848 The Company recognized depreciation for property and equipment of $ 0.5 million and $ 0.5 million for the three months ended March 31, 2022 and 2021, respectively. Accrued Liabilities Accrued liabilities consisted of the following (in thousands): March 31, December 31, Accrued research and development expenses $ 3,739 $ 2,404 Accrued compensation 1,380 3,573 Accrued professional services 417 1,274 Accrued construction costs 591 1,917 Other accrued expenses 84 82 Total accrued liabilities $ 6,211 $ 9,250

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	5. Commitments and Contingencies Leases The Company leases its offices and laboratory in Brisbane, California, or the Brisbane Lease, under a ten-year noncancelable lease agreement that ends in October 2031 with a ten-year renewable option. In November 2021, the Company subleased unoccupied space for two years starting from December 2021 for aggregate sublease payments of $ 3.4 million. The sublease income, while it reduces the rent expense, is not considered in the value of the right-of-use assets or lease liabilities. The Company’s sublease income was $ 0.4 million for the three months ended March 31, 2022. As of March 31, 2022, the operating lease right-of-use assets were $ 20.1 million and lease liabilities were $ 34.2 million in its condensed consolidated balance sheet. The weighted average remaining lease term is 9.6 years. The weighted average incremental borrowing rate used to measure the operating lease liability is 8.4 % . Operating lease cost for the three months ended March 31, 2022 and 2021 were $ 0.5 million and $ 0.1 million, respectively. Variable lease payments for the three months ended March 31, 2022 and 2021 were $ 0.3 million and $ 34,000 , respectively. Future minimum lease payments and related lease liabilities as of March 31, 2022, were as follows: As of March 31: (in thousands) 2022 (remaining nine months) $ 3,067 2023 4,742 2024 4,907 2025 5,079 2026 and thereafter 32,833 Total undiscounted lease payments 50,628 Less: Imputed interest ( 16,451 ) Total $ 34,177 License and Other Agreements In November 2011, the Company entered into an exclusive licensing agreement, or the Stanford Agreement, with The Board of Trustees of the Leland Stanford Junior University, or Stanford, whereby the Company was granted an exclusive, worldwide, royalty-bearing, sublicensable license, under certain patent rights, or the Licensed Patents, to make, use, offer for sale, sell, import and otherwise commercialize products covered by the Licensed Patents for human or animal diseases, disorders or conditions. Under the Stanford Agreement, the Company made an upfront payment and is obligated to pay Stanford annual license maintenance fees, potential future milestone payments totaling up to $ 0.5 million, and royalty payments at a rate equal to a low single-digit percentage of worldwide net sales of licensed products. The Company did not achieve any milestones or make any milestone payments for the three months ended March 31, 2022 and 2021. In December 2016, the Company entered into a sponsored research agreement, with a not-for-profit entity to perform research on multiple sclerosis. The sponsored research agreement was amended in March 2019, or as amended, the Sponsored Research Agreement. Under the terms of the Sponsored Research Agreement, the Company may receive up to $ 0.7 million in funding. If within 15 years of the end of the Sponsored Research Agreement, the Company files a marketing authorization application for a product treating multiple sclerosis, the Company will be obligated to pay milestone payments up to four times the amounts received under the Sponsored Research Agreement. The Company has received $ 0.6 million in funding to date, which was recorded as other income. The Company recognized no income during the three months ended March 31, 2022 and $ 0.1 million in income during the three months ended March 31, 2021. Guarantees and Indemnifications In the normal course of business, the Company enters into agreements that contain a variety of representations and provide for general indemnification. The Company’s exposure under these agreements is unknown because it involves claims that may be made against the Company in the future. To date, the Company has no t paid any claims or been required to defend any action related to its indemnification obligations. As of March 31, 2022, the Company did no t have any material indemnification claims that were probable or reasonably possible and consequently has not recorded related liabilities.

Stockholder's Equity

Stockholder's Equity	3 Months Ended
	Mar. 31, 2022
Stockholders Equity Note [Abstract]
Stockholders' Equity	6. Stockholders’ Equity Common Stock The Company has reserved the following shares of common stock for issuance as follows: March 31, December 31, Stock options issued and outstanding 6,883,024 5,662,824 Stock options reserved for 2020 Incentive 2,104,124 2,039,951 Unvested restricted stock units outstanding 305,350 50,000 Common stock reserved for 2021 ATM 5,265,929 5,265,929 Common stock reserved for Employee Stock 1,115,383 729,775 Total common stock reserved 15,673,810 13,748,479 At-the-Market Offering In August 2021, the Company entered into a sales agreement with Cowen and Company LLC, or Cowen, as sales agent, pursuant to which the Company may issue and sell shares of its common stock for an aggregate maximum offering price of $ 100.0 million under an at-the-market offering program, or 2021 ATM program. The Company will pay Cowen up to 3 % of gross proceeds for the common stock sold through the 2021 ATM program. As of March 31, 2022, no shares of common stock have been sold under the 2021 ATM program.

Equity Incentive Plan

Equity Incentive Plan	3 Months Ended
	Mar. 31, 2022
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity Incentive Plan	7. Equity Incentive Plan In July 2020, the Company’s board of directors and stockholders adopted and approved the 2020 Incentive Award Plan, or the 2020 Plan, and the Employee Stock Purchase Plan, or the ESPP, which became effective in connection with the Company’s initial public offering, or the IPO. The Company may not grant any additional awards under the 2011 Equity Incentive Plan, or the 2011 Plan. The 2011 Plan will continue to govern outstanding equity awards granted thereunder. 2020 Equity Incentive Plan The number of shares of common stock reserved for issuance under the 2020 Plan automatically increases on the first day of January, in an amount equal to 4 % of the total number of shares of the Company’s capital stock outstanding on the last day of the preceding year, or a lesser number of shares determined by the Company’s board of directors. Awards granted under the 2020 Plan expire no later than ten years from the date of grant. For Incentive Stock Options, or ISOs, and Nonstatutory Stock Options, or NSOs, the option price shall not be less than 100 % of the estimated fair value on the date of grant. Options granted typically vest over a four-year period but may be granted with different vesting terms. As of March 31, 2022, there were 2,104,124 shares available for issuance under the 2020 Plan. Stock options Stock option activity under the 2011 Plan and the 2020 Plan was as follows: Number of Weighted- Weighted- Aggregate Balances as of December 31, 2021 5,662,824 $ 16.98 8.26 $ 10,186 Additional shares authorized Stock options granted 1,945,155 $ 6.82 Stock options exercised ( 2,711 ) $ 7.38 Stock options forfeited ( 722,244 ) $ 16.69 Balances as of March 31, 2022 6,883,024 $ 14.14 8.29 $ 366 Exercisable as of March 31, 2022 2,293,593 $ 11.71 6.49 $ 366 The total intrinsic value of options exercised during the three months ended March 31, 2022 and 2021 were $ 2,500 and $ 1.1 million, respectively. The intrinsic value is the difference between the fair value of the Company’s common stock at the time of exercise and the exercise price of the stock option. As of March 31, 2022, the total unrecognized stock-based compensation cost related to outstanding unvested stock options that are expected to vest was $ 50.7 million, which the Company expects to recognize over an estimated weighted-average period of 2.99 years. Restricted Stock Units RSUs are equity awards that entitle the holder to receive shares of the Company’s common stock upon vesting. The RSUs cannot be transferred and the awards are subject to forfeiture if the holder’s employment terminates prior to the release of the vesting restrictions. The RSUs generally vest over a three-year period in equal amounts on an annual basis, provided the employee remains continuously employed with the Company. The fair value of the RSUs is equal to the closing price of the Company’s common stock on the grant date. A summary of RSU activity under the 2020 Plan and related information is as follows: Number of Shares Weighted-Average Grant Date Fair Value Per Share Unvested as of December 31, 2021 50,000 $ 12.84 Granted 294,630 6.94 Cancelled ( 39,280 ) 7.69 Unvested as of March 31, 2022 $ 305,350 $ 7.81 As of March 31, 2022, unrecognized stock-based compensation expense related to outstanding unvested RSUs was $ 2.3 million, which is expected to be recognized over a weighted-average period of 2.84 years. Employee Stock Purchase Plan The ESPP enables eligible employees to purchase shares of the Company's common stock at the end of each offering period at a price equal to 85 % of the fair market value of the shares on the first business day or the last business day of the offering period, whichever is lower. Eligible employees generally include all employees. Share purchases are funded through payroll deductions of at least 1 %, and up to 15 % of an employee’s eligible compensation for each payroll period. The number of shares reserved for issuance under the ESPP increase automatically on the first day of each fiscal year, by a number equal to the least of 360,086 shares, 1 % of the shares of common stock outstanding on the last day of the immediately preceding fiscal year, or such number of shares determined by the Company’s board of directors. As of March 31, 2022, 1,115,383 shares were available for future purchase. The ESPP generally provides for six-month consecutive offering periods beginning on May 15 th and November 15 th of each year. The ESPP is a compensatory plan as defined by the authoritative guidance for stock compensation. As such, stock-based compensation expense has been recorded for the three months ended March 31, 2022. Stock-Based Compensation Expense The total stock-based compensation expense recognized related to the Company’s equity incentive plans was as follows (in thousands): Three Months Ended 2022 2021 Research and development $ 1,959 $ 1,546 General and administrative 2,293 1,416 Total stock-based compensation expense $ 4,252 $ 2,962 To determine the value of stock option awards for stock-based compensation purposes, the Company uses the Black-Scholes option pricing model and the assumptions discussed below. Each of these inputs is subjective and generally requires significant judgment. Fair Value of Common Stock— Historically, for all periods prior to the IPO in July 2020, fair values of the shares of common stock underlying the Company’s share-based awards were estimated on each grant date by the Company’s board of directors. The board of directors considered, among other things, valuations of the Company’s common stock, which were prepared by an independent third-party valuation firm in accordance with the guidance provided by the American Institute of Certified Public Accountants 2013 Practice Aid, Valuation of Privately-Held-Company Equity Securities Issued as Compensation . After the completion of the IPO in July 2020, the fair value of each share of underlying common stock is based on the closing price of the Company’s common stock as reported on the date of grant on the Nasdaq Global Select Market. Expected Term —The Company’s expected term represents the period that the Company’s stock-based awards are expected to be outstanding. The Company’s historical share option exercise information is limited due to a lack of sufficient data points and did not provide a reasonable basis upon which to estimate an expected term. The expected term for option grants is therefore determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term). Expected Volatility —Because the Company does not have sufficient trading history for its common stock, the expected volatility was estimated based on the average volatility for comparable publicly traded life science companies over a period equal to the expected term of the stock option grants. The comparable companies were chosen based on the similar size, stage in the life cycle, or area of specialty. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available and to align with the Company’s expected term. Risk-Free Interest Rate —The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of the option. Dividend Yield —The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero. The fair value of each award issued was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions: Three Months Ended 2022 2021 Expected term (in years) 4.33 - 6.08 4.33 - 6.02 Expected volatility 79 % - 82 % 90 % Risk-free interest rate 1.49 % - 2.11 % 0.35 % - 1.02 % Dividend yield — —

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2022
Income Tax Disclosure [Abstract]
Income Taxes	8. Income Taxes For the three months ended March 31, 2022 and 2021, the Company incurred insignificant amounts for an income tax provision. The U.S. federal and California deferred tax assets generated from the Company’s net operating losses have been fully reserved, as the Company believes it is not more likely than not that the benefit will be realized.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	9. Net Loss Per Share Attributable to Common Stockholders The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share due to their anti-dilutive effect: Three Months Ended 2022 2021 Stock options to purchase common stock 6,883,024 5,373,215 Shares subject to Employee Stock Purchase Plan 81,675 4,393 Unvested restricted stock units 305,350 — Total 7,270,049 5,377,608

Basis of Presentation and Sig_2

Basis of Presentation and Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States, or GAAP, and applicable rules and regulations of the SEC regarding interim financial reporting. The condensed consolidated balance sheet as of March 31, 2022, and the condensed consolidated statements of operations, comprehensive loss, changes in stockholders’ equity and cash flows for the three months ended March 31, 2022 and 2021 are unaudited. These unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s consolidated financial position as of March 31, 2022 and its results of operations and cash flows for the three months ended March 31, 2022 and 2021. The financial data and the other financial information contained in these notes to condensed consolidated financial statements related to the three-month periods are also unaudited. The results of operations for the three months ended March 31, 2022 are not necessarily indicative of the results to be expected for the year ending December 31, 2022 or for any other future annual or interim period. The condensed consolidated balance sheet as of December 31, 2021 included herein was derived from the audited financial statements as of that date. These condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021, filed with the SEC on March 1, 2022. In the second quarter of 2021, the Company adopted ASU No. 2016-02, Leases (Topic 842), using the modified retrospective approach as of January 1, 2021. The adoption of Topic 842 as of January 1, 2021 resulted in the recognition of right-of-use assets of $ 0.5 million, corresponding lease liabilities of $ 0.6 million, the derecognition of the deferred rent liability of $ 1.4 million, and the recognition of a liability of $ 1.3 million related to the reallocation of the consideration of the Company’s lease pending the commencement of the second lease component in May 2021 (see Note 5— Commitments and Contingencies ). The adoption resulted in additional $ 54,000 of rent expense for the first quarter of 2021. The Company restated its condensed consolidated statement of operations for the three months ended March 31, 2021 to reflect the adoption of Topic 842 and recorded $ 54,000 to general and administrative expense, resulting in a corresponding increase in total operating expense and net loss. The restatement impacts the net loss presented in the condensed consolidated statement of comprehensive loss, condensed consolidated statement of stockholders’ equity, and condensed consolidated statement of cash flows.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported expenses during the reporting period. On an ongoing basis, management evaluates its estimates, including but not limited to fair value of investments, useful lives for property and equipment, incremental borrowing rate used in lease accounting, stock options, income taxes and certain accruals. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates.
Principles of Consolidation	Principles of Consolidation The condensed consolidated financial statements include the operations of Annexon, Inc. and its wholly-owned subsidiary and include the results of operations and cash flows of these entities. All intercompany balances and transactions have been eliminated in consolidation.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid instruments with an original maturity of three months or less at time of purchase to be cash equivalents. Cash equivalents, which includes amounts invested in money market funds, are stated at fair value. Restricted cash as of March 31, 2022 relates to the letters of credit established for the Company’s office leases. The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets that sum to the total of the same amounts shown in the condensed consolidated statements of cash flows: March 31, December 31, Cash $ 583 $ 734 Cash equivalents 112,245 74,109 Cash and cash equivalents 112,828 74,843 Restricted cash 1,166 1,166 Cash, cash equivalents and restricted cash $ 113,994 $ 76,009
Short-Term Investments	Short-Term Investments Short-term investments have been classified as available-for-sale and are carried at estimated fair value as determined based upon quoted market prices or pricing models for similar securities. The Company determines the appropriate classification of its investments in debt securities at the time of purchase. Available-for-sale securities are classified as current based on their availability for use in current operations. Unrealized gains and losses are excluded from earnings and are reported as a component of other comprehensive loss. The Company periodically evaluates whether declines in fair values of its marketable securities below their book value are other-than-temporary. This evaluation consists of several qualitative and quantitative factors regarding the severity and duration of the unrealized loss as well as the Company’s ability and intent to hold the marketable security until a forecasted recovery occurs. Additionally, the Company assesses whether it has plans to sell the security or it is more likely than not it will be required to sell any marketable securities before recovery of its amortized cost basis. Impairment assessments are made at the individual security level each reporting period. When the fair value of an available-for- sale security is less than its cost at the balance sheet date, a determination is made as to whether the impairment is other-than-temporary and, if it is other-than-temporary, an impairment loss is recognized in other income, net, equal to the difference between the investment’s amortized cost and fair value at such date. The cost of investments sold is based on the specific-identification method. Interest on marketable securities is included in other income, net.
Foreign Currencies	Foreign Currencies The Company’s reporting currency is the U.S. dollar. The functional currency of the Company’s subsidiary located in Australia is the Australian Dollar. Balance sheets prepared in the functional currencies are translated to the reporting currency at exchange rates in effect at the end of the accounting period, except for stockholders’ equity accounts, which are translated at rates in effect when these balances were originally recorded. Revenue and expense accounts are translated using a weighted-average rate during the year. The resulting foreign currency translation adjustments are recorded as a separate component of accumulated other comprehensive loss in the accompanying condensed consolidated balance sheets. Foreign currency translation adjustments for the three months ended March 31, 2022 and 2021 were a $ 3,000 gain and a $ 1,000 loss, respectively. Gains and losses resulting from exchange rate changes on transactions denominated in a currency other than the local currency are included in earnings as incurred.
Research and Development Expense	Research and Development Expense Research and development expenses consist primarily of direct and indirect costs incurred for the development of the Company’s product candidates. Direct expenses include (i) preclinical and clinical outside service costs associated with discovery, preclinical and clinical testing of the Company’s product candidates; (ii) professional services agreements with third-party contract organizations, investigative clinical trial sites and consultants that conduct research and development activities on the Company’s behalf; (iii) contract manufacturing costs to produce clinical trial materials; and (iv) laboratory supplies and materials. Indirect expenses include (A) compensation and personnel-related expenses (including stock-based compensation); (B) allocated expenses for facilities and depreciation; and (C) other indirect costs. Research and development costs are expensed as incurred. Payments made to third parties are under agreements that are generally cancelable by the Company. Advance payments for research and development activities are deferred as prepaid expenses. The prepaid amounts are expensed as the related services are performed. The Company estimates preclinical studies and clinical trial expenses based on the services performed pursuant to contracts with research institutions and clinical research organizations that conduct and manage preclinical studies and clinical trials on the Company’s behalf. In accruing service fees, the Company estimates the period over which services will be performed and the level of effort to be expended in each period. These estimates are based on the Company’s communications with the third-party service providers and on information available at each balance sheet date. If the actual timing of the performance of services or the level of effort varies significantly from the estimate, the Company will adjust the accrual accordingly to reflect the best information available at the time of the financial statement issuance. The Company has not experienced any material differences between accrued costs and actual costs incurred since its inception.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation arrangements with employees, non-employee directors and consultants using a fair value method which requires the recognition of compensation expense for costs related to all stock-based payments, including stock options and restricted stock units, or RSUs. The fair value method requires the Company to estimate the fair value of stock options to employees and non-employee directors on the date of grant using the Black-Scholes option pricing model. The fair value of RSU awards is based on the fair value of the underlying common stock as of the grant date. The Company grants certain employees performance-based stock options. For awards that include performance conditions, no compensation cost is recognized until the performance goals are probable of being met, at which time the cumulative compensation expense from the service inception date would be recognized. Stock-based compensation costs are based on the fair value of the underlying option calculated using the Black-Scholes option pricing model and recognized as expense on a straight-line basis (for all but performance-based awards for which the accelerated method is used) over the requisite service period, which is the vesting period. Determining the appropriate fair value model and related assumptions requires judgment, including estimating the fair value of the underlying common stock, expected term, expected stock price volatility, risk-free interest rate and dividend yield. The Company accounts for forfeitures as they occur.
Net Loss Per Share Attributable to Common Stockholders	Net Loss Per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period, without consideration for potential dilutive shares of common stock. As the Company was in a loss position for all periods presented, basic net loss per share attributable to common stockholders is the same as diluted net loss per share attributable to common stockholders because the effects of potentially dilutive securities are antidilutive.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash and cash equivalents and short-term investments. The Company’s cash and cash equivalents and short-term investments are held by high credit quality financial institutions in the United States. At times, such deposits may be in excess of the Federal Depository Insurance Corporation insured limits. Management believes that the financial institutions are financially sound, and accordingly, minimal credit risk exists with respect to the financial institutions.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements The Company has implemented all new accounting pronouncements that are in effect and that may impact its condensed consolidated financial statements and does not believe that there are any other new pronouncements that have been issued that might have a material impact on its financial position or results of operations.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements The Company does not believe that any recently issued effective pronouncements, or pronouncements issued but not yet effective, if adopted, would have a material impact on its financial position or results of operations.

Basis of Presentation and Sig_3

Basis of Presentation and Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed consolidated balance sheets that sum to the total of the same amounts shown in the condensed consolidated statements of cash flows: March 31, December 31, Cash $ 583 $ 734 Cash equivalents 112,245 74,109 Cash and cash equivalents 112,828 74,843 Restricted cash 1,166 1,166 Cash, cash equivalents and restricted cash $ 113,994 $ 76,009

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2022
Fair Value Disclosures [Abstract]
Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables summarize the fair value of the Company’s financial assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): March 31, 2022 Valuation Amortized Gross Gross Aggregate Assets: Cash equivalents: Money market funds Level 1 $ 112,245 $ — $ — $ 112,245 Short-term investments: Commercial paper Level 2 42,917 — ( 77 ) 42,840 Corporate debt Level 2 21,501 — ( 28 ) 21,473 Government bonds Level 2 29,707 — ( 189 ) 29,518 Total assets $ 206,370 $ — $ ( 294 ) $ 206,076 December 31, 2021 Valuation Amortized Gross Gross Aggregate Assets: Cash equivalents: Money market funds Level 1 $ 74,109 $ — $ — $ 74,109 Short-term investments: Commercial paper Level 2 85,352 — ( 27 ) 85,325 Corporate bonds Level 2 48,814 — ( 24 ) 48,790 Government bonds 33,809 — ( 52 ) 33,757 Total assets $ 242,084 $ — $ ( 103 ) $ 241,981

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2022
Disclosure Of Balance Sheet Components [Abstract]
Summary of Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): March 31, December 31, Prepaid research and development costs $ 3,267 $ 3,002 Prepaid insurance 744 1,282 Other prepaid expenses 450 231 Other current assets 134 463 Total prepaid expenses and other current assets $ 4,595 $ 4,978
Summary of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): March 31, December 31, Leasehold improvements $ 17,051 $ 16,594 Laboratory equipment 1,348 1,353 Furniture and fixtures 668 649 Computer equipment and software 33 41 Total property and equipment, gross 19,100 18,637 Less: accumulated depreciation ( 1,295 ) ( 789 ) Total property and equipment, net $ 17,805 $ 17,848
Summary of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): March 31, December 31, Accrued research and development expenses $ 3,739 $ 2,404 Accrued compensation 1,380 3,573 Accrued professional services 417 1,274 Accrued construction costs 591 1,917 Other accrued expenses 84 82 Total accrued liabilities $ 6,211 $ 9,250

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2022
Commitments And Contingencies Disclosure [Abstract]
Future Minimum Lease Payments and Related Lease Liabilities	Future minimum lease payments and related lease liabilities as of March 31, 2022, were as follows: As of March 31: (in thousands) 2022 (remaining nine months) $ 3,067 2023 4,742 2024 4,907 2025 5,079 2026 and thereafter 32,833 Total undiscounted lease payments 50,628 Less: Imputed interest ( 16,451 ) Total $ 34,177

Stockholder's Equity (Tables)

Stockholder's Equity (Tables)	3 Months Ended
	Mar. 31, 2022
Stockholders Equity Note [Abstract]
Schedule of Common Stock Reserved for Future Issuance	The Company has reserved the following shares of common stock for issuance as follows: March 31, December 31, Stock options issued and outstanding 6,883,024 5,662,824 Stock options reserved for 2020 Incentive 2,104,124 2,039,951 Unvested restricted stock units outstanding 305,350 50,000 Common stock reserved for 2021 ATM 5,265,929 5,265,929 Common stock reserved for Employee Stock 1,115,383 729,775 Total common stock reserved 15,673,810 13,748,479

Equity Incentive Plan (Tables)

Equity Incentive Plan (Tables)	3 Months Ended
	Mar. 31, 2022
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Activity	Stock options Stock option activity under the 2011 Plan and the 2020 Plan was as follows: Number of Weighted- Weighted- Aggregate Balances as of December 31, 2021 5,662,824 $ 16.98 8.26 $ 10,186 Additional shares authorized Stock options granted 1,945,155 $ 6.82 Stock options exercised ( 2,711 ) $ 7.38 Stock options forfeited ( 722,244 ) $ 16.69 Balances as of March 31, 2022 6,883,024 $ 14.14 8.29 $ 366 Exercisable as of March 31, 2022 2,293,593 $ 11.71 6.49 $ 366
Summary of RSU Activity under 2020 Plan	A summary of RSU activity under the 2020 Plan and related information is as follows: Number of Shares Weighted-Average Grant Date Fair Value Per Share Unvested as of December 31, 2021 50,000 $ 12.84 Granted 294,630 6.94 Cancelled ( 39,280 ) 7.69 Unvested as of March 31, 2022 $ 305,350 $ 7.81
Summary of Stock-Based Compensation Expense	The total stock-based compensation expense recognized related to the Company’s equity incentive plans was as follows (in thousands): Three Months Ended 2022 2021 Research and development $ 1,959 $ 1,546 General and administrative 2,293 1,416 Total stock-based compensation expense $ 4,252 $ 2,962
Summary of Fair Value of Each Award Issued Estimated on the Date of Grant Using the Black-Scholes Option Pricing Model	The fair value of each award issued was estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions: Three Months Ended 2022 2021 Expected term (in years) 4.33 - 6.08 4.33 - 6.02 Expected volatility 79 % - 82 % 90 % Risk-free interest rate 1.49 % - 2.11 % 0.35 % - 1.02 % Dividend yield — —

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Summary of Outstanding Potentially Dilutive Shares Excluded From Calculation of Diluted Net Loss Per Share	The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share due to their anti-dilutive effect: Three Months Ended 2022 2021 Stock options to purchase common stock 6,883,024 5,373,215 Shares subject to Employee Stock Purchase Plan 81,675 4,393 Unvested restricted stock units 305,350 — Total 7,270,049 5,377,608

Organization - Additional Infor

Organization - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accounting Policies [Abstract]
Accumulated deficit	$ 331,688	$ 296,315
Cash and cash equivalents and short-term investments	$ 206,700

Basis of Presentation and Sig_4

Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Jan. 01, 2021
Basis Of Presentation And Significant Accounting Policies [Line Items]
Operating lease right-of-use assets	$ 20,103,000		$ 20,333,000
Lease liabilities	34,177,000
General and administrative	8,428,000	$ 5,506,000
Foreign currency translation adjustment	$ 3,000	(1,000)
ASU 2016-02 [Member]
Basis Of Presentation And Significant Accounting Policies [Line Items]
Change in accounting principle, ASU adopted	true
Change in accounting principle, ASU, adoption date	Jan. 1, 2021
Operating lease right-of-use assets				$ 500,000
Lease liabilities				600,000
Derecognition of deferred rent liability				1,400,000
Recognition of liability related to reallocation of consideration of lease pending commencement of second lease component				$ 1,300,000
Operating lease additional rent expense		54,000
General and administrative		$ 54,000

Basis of Presentation and Sig_5

Basis of Presentation and Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]
Cash	$ 583	$ 734
Cash equivalents	112,245	74,109
Cash and cash equivalents	112,828	74,843
Restricted cash	1,166	1,166
Cash, cash equivalents and restricted cash	$ 113,994	$ 76,009

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	$ 206,370	$ 242,084
Gross Unrealized Holding Losses	(294)	(103)
Aggregate Fair Value	206,076	241,981
Level 1 [Member] | Money Market Funds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	112,245	74,109
Aggregate Fair Value	112,245	74,109
Level 2 [Member] | Commercial Paper [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	42,917	85,352
Gross Unrealized Holding Losses	(77)	(27)
Aggregate Fair Value	42,840	85,325
Level 2 [Member] | Corporate Debt [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	21,501
Gross Unrealized Holding Losses	(28)
Aggregate Fair Value	21,473
Level 2 [Member] | Government Bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost		33,809
Gross Unrealized Holding Losses		(52)
Aggregate Fair Value		33,757
Level 2 [Member] | Corporate Bonds [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	29,707	48,814
Gross Unrealized Holding Losses	(189)	(24)
Aggregate Fair Value	$ 29,518	$ 48,790

Balance Sheet Components - Summ

Balance Sheet Components - Summary of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Prepaid Expense And Other Assets Current [Abstract]
Prepaid research and development costs	$ 3,267	$ 3,002
Prepaid insurance	744	1,282
Other prepaid expenses	450	231
Other current assets	134	463
Total prepaid expenses and other current assets	$ 4,595	$ 4,978

Balance Sheet Components - Su_2

Balance Sheet Components - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 19,100	$ 18,637
Less: accumulated depreciation	(1,295)	(789)
Total property and equipment, net	17,805	17,848
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Total property and equipment, gross	17,051	16,594
Laboratory Equipment [Member]
Property Plant And Equipment [Line Items]
Total property and equipment, gross	1,348	1,353
Furniture and Fixtures [Member]
Property Plant And Equipment [Line Items]
Total property and equipment, gross	668	649
Computer Equipment and Software [Member]
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 33	$ 41

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Prepaid Expense And Other Assets Current [Abstract]
Depreciation expense	$ 0.5	$ 0.5

Balance Sheet Components - Su_3

Balance Sheet Components - Summary of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Accrued Liabilities Current [Abstract]
Accrued research and development expenses	$ 3,739	$ 2,404
Accrued compensation	1,380	3,573
Accrued professional services	417	1,274
Accrued construction costs	591	1,917
Other accrued expenses	84	82
Total accrued liabilities	$ 6,211	$ 9,250

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Nov. 01, 2021USD ($)	Mar. 31, 2019USD ($)	Nov. 30, 2011USD ($)	Mar. 31, 2022USD ($)Claim	Mar. 31, 2021USD ($)	Dec. 31, 2021USD ($)
Gain Contingencies [Line Items]
Aggregate sublease payment receivable	$ 3,400,000
Sublease income				$ 400,000
Operating lease right-of-use asset				20,103,000		$ 20,333,000
Lease liabilities				$ 34,177,000
Weighted average incremental borrowing rate				8.40%
Operating lease cost				$ 500,000	$ 100,000
Variable lease payments				300,000	34,000
Income (loss)				(35,373,000)	(26,060,000)
Loss contingency accrual				$ 0
Indemnification Agreement [Member]
Gain Contingencies [Line Items]
Loss contingency pending claims | Claim				0
Stanford Agreement [Member] | Research and Development Arrangement [Member]
Gain Contingencies [Line Items]
Sponsor research agreements, commitment amount			$ 500,000
Proceeds from funding				$ 600,000
Sponsored Research Agreement [Member]
Gain Contingencies [Line Items]
Maximum threshold period allowed for filing market authorization		15 years
Income (loss)				$ 0	$ 100,000
Sponsored Research Agreement [Member] | Research and Development Arrangement [Member]
Gain Contingencies [Line Items]
Maximum expected research funding		$ 700,000
Brisbane, California [Member]
Gain Contingencies [Line Items]
Operating lease, term of contract				10 years
Operating lease, expiration month and year				2031-10
Operating lease, renewal term				10 years
Operating lease right-of-use asset				$ 20,100,000
Lease liabilities				$ 34,200,000
Weighted average remaining lease term				9 years 7 months 6 days

Commitments and Contingencies_2

Commitments and Contingencies - Future Minimum Lease Payments and Related Lease Liabilities (Detail) $ in Thousands	Mar. 31, 2022USD ($)
Commitments And Contingencies Disclosure [Abstract]
2022 (remaining nine months)	$ 3,067
2023	4,742
2024	4,907
2025	5,079
2026 and thereafter	32,833
Total undiscounted lease payments	50,628
Less: Imputed interest	(16,451)
Lease liabilities	$ 34,177

Stockholder's Equity - Schedule

Stockholder's Equity - Schedule of Common Stock Reserved for Future Issuance (Detail) - shares	Mar. 31, 2022	Dec. 31, 2021
Class Of Stock [Line Items]
Common stock reserved	6,883,024	5,662,824
Common stock reserved	2,104,124
Common stock reserved	15,673,810	13,748,479
Stock Options Issued and Outstanding [Member]
Class Of Stock [Line Items]
Common stock reserved	6,883,024	5,662,824
Stock Options Reserved for 2020 Incentive Award Plan [Member]
Class Of Stock [Line Items]
Common stock reserved	2,104,124	2,039,951
Unvested Restricted Stock Units Outstanding [Member]
Class Of Stock [Line Items]
Common stock reserved	305,350	50,000
Common Stock Reserved for Employee Stock Purchase Plan [Member]
Class Of Stock [Line Items]
Common stock reserved	1,115,383	729,775
2021 ATM Program [Member]
Class Of Stock [Line Items]
Common stock reserved	5,265,929	5,265,929

Stockholder's Equity - Addition

Stockholder's Equity - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended
	Aug. 31, 2021	Mar. 31, 2022	Dec. 31, 2021
Class Of Stock [Line Items]
Common stock		$ 39	$ 39
Sales Agreement with Cowen and Company LLC [Member] | 2021 ATM Program [Member]
Class Of Stock [Line Items]
Common stock	$ 100,000
Percentage of gross proceeds of common stock to be paid	3.00%

Equity Incentive Plan - Additio

Equity Incentive Plan - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of number of shares of capital stock outstanding on last day of preceding year	4.00%
Stock option grants description	Awards granted under the 2020 Plan expire no later than ten years from the date of grant. For Incentive Stock Options, or ISOs, and Nonstatutory Stock Options, or NSOs, the option price shall not be less than 100% of the estimated fair value on the date of grant. Options granted typically vest over a four-year period but may be granted with different vesting terms.
Option expiry period	10 years
Vesting Period	4 years
Options available for future grant	2,104,124
Intrinsic value of options exercised	$ 2,500	$ 1,100,000
Unrecognized stock-based compensation cost expected period for recognition	2 years 11 months 26 days
Common stock for future issuance	15,673,810		13,748,479
Total stock-based compensation expense	$ 4,252,000	$ 2,962,000
Incentive Stock Options, or ISOs, and Nonstatutory Stock Options, or NSOs [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase of Common stock at end of each offering period at price equal to percentage of fair market value of shares	100.00%
Options Issued and Outstanding [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation cost	$ 50,700,000
Restricted Stock Units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation cost	$ 2,300,000
Unrecognized stock-based compensation cost expected period for recognition	2 years 10 months 2 days
Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase of Common stock at end of each offering period at price equal to percentage of fair market value of shares	85.00%
Share purchases funded through payroll deductions minimum percentage of employee's eligible compensation	1.00%
Share purchases funded through payroll deductions maximum percentage of employee's eligible compensation	15.00%
Common stock for future issuance	1,115,383		729,775
Maximum number of shares to be issued in accordance with plan as a proportion of outstanding capital stock	360,086
Percentage of shares of common stock outstanding on last day of immediately preceding fiscal year	1.00%

Equity Incentive Plan - Summary

Equity Incentive Plan - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of shares, Beginning balance	5,662,824
Number of shares, Stock options granted	1,945,155
Number of shares, Stock options exercised	(2,711)
Number of shares, Stock options forfeited	(722,244)
Number of shares, Ending balance	6,883,024	5,662,824
Number of shares, Exercisable	2,293,593
Weighted- average exercise price per share, Beginning balance	$ 16.98
Weighted- average exercise price per share, Stock options granted	6.82
Weighted- average exercise price per share, Stock options exercised	7.38
Weighted average exercise price per share, Stock options forfeited	16.69
Weighted- average exercise price per share, Ending balance	14.14	$ 16.98
Weighted- average exercise price per share, Exercisable	$ 11.71
Weighted- average remaining contractual term	8 years 3 months 14 days	8 years 3 months 3 days
Weighted- average remaining contractual term, Exercisable	6 years 5 months 26 days
Aggregate intrinsic value	$ 366	$ 10,186
Aggregate intrinsic value, Exercisable	$ 366

Equity Incentive Plan - Summa_2

Equity Incentive Plan - Summary of RSU Activity under 2020 Plan (Detail)	3 Months Ended
	Mar. 31, 2022$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Unvested as of December 31, 2021 | shares	50,000
Number of Shares, Granted | shares	294,630
Number of Shares, Cancelled | shares	(39,280)
Number of Shares, Unvested as of March 31, 2022 | shares	305,350
Weighted-Average Grant Date Fair Value Per Share, Granted Unvested as of December 31, 2021 | $ / shares	$ 12.84
Weighted-Average Grant Date Fair Value Per Share, Granted | $ / shares	6.94
Weighted-Average Grant Date Fair Value Per Share, Cancelled | $ / shares	7.69
Weighted-Average Grant Date Fair Value Per Share, Granted Unvested as of March 31, 2022 | $ / shares	$ 7.81

Equity Incentive Plan - Summa_3

Equity Incentive Plan - Summary of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 4,252	$ 2,962
Research and Development [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	1,959	1,546
General and Administrative [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total stock-based compensation expense	$ 2,293	$ 1,416

Equity Incentive Plan - Summa_4

Equity Incentive Plan - Summary of Fair Value of Each Award Issued Estimated on the Date of Grant Using the Black-Scholes Option Pricing Model (Detail)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility		90.00%
Expected volatility, Minimum	79.00%
Expected volatility, Maximum	82.00%
Risk-free interest rate, Minimum	1.49%	0.35%
Risk-free interest rate, Maximum	2.11%	1.02%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	4 years 3 months 29 days	4 years 3 months 29 days
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years 29 days	6 years 7 days

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Summary of Outstanding Potentially Dilutive Shares Excluded From Calculation of Diluted Net Loss Per Share (Detail) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	7,270,049	5,377,608
Shares Subject to Employee Stock Purchase Plan [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	81,675	4,393
Stock Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	6,883,024	5,373,215
Unvested Restricted Stock Units [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from the computation of diluted net loss per share	305,350