Adverum Biotechnologies (ADVM) 10-Q 9 Nov 23 2023 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2023	Oct. 31, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-36579
Entity Registrant Name	Adverum Biotechnologies, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-5258327
Entity Address, Address Line One	100 Cardinal Way
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94063
City Area Code	650
Local Phone Number	656-9323
Title of 12(b) Security	Common Stock, $0.0001 par value
Trading Symbol	ADVM
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		101,027,174
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001501756
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 105,366	$ 68,431
Short-term investments	11,716	117,158
Prepaid expenses and other current assets	7,514	5,006
Total current assets	124,596	190,595
Operating lease right-of-use assets	52,757	78,934
Property and equipment, net	15,497	34,927
Restricted cash	2,650	2,503
Deposit and other long-term assets	1,270	1,413
Total assets	196,770	308,372
Current liabilities:
Accounts payable	2,170	2,238
Accrued expenses and other current liabilities	16,362	16,767
Lease liability, current portion	10,324	13,241
Total current liabilities	28,856	32,246
Lease liability, net of current portion	65,200	93,561
Other non-current liabilities	0	1,047
Total liabilities	94,056	126,854
Stockholders’ equity:
Preferred stock	0	0
Common stock	10	10
Additional paid-in capital	999,319	985,651
Accumulated other comprehensive loss	(552)	(1,531)
Accumulated deficit	(896,063)	(802,612)
Total stockholders’ equity	102,714	181,518
Total liabilities and stockholders’ equity	$ 196,770	$ 308,372

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
License revenue	$ 0	$ 0	$ 3,600	$ 0
Operating expenses:
Research and development	20,740	23,849	62,398	77,078
General and administrative	13,789	17,188	39,035	46,117
Total operating expenses	34,529	41,037	101,433	123,195
Operating loss	(34,529)	(41,037)	(97,833)	(123,195)
Other income, net	1,661	923	4,437	1,450
Net loss before income taxes	(32,868)	(40,114)	(93,396)	(121,745)
Income tax provision	(17)	(17)	(55)	(55)
Net loss	(32,885)	(40,131)	(93,451)	(121,800)
Other comprehensive income (loss):
Net unrealized gain/(loss) on marketable securities	66	(127)	1,003	(1,189)
Foreign currency translation adjustment	(12)	(30)	(24)	(50)
Comprehensive loss	$ (32,831)	$ (40,288)	$ (92,472)	$ (123,039)
Net loss per share — basic (in USD per share)	$ (0.33)	$ (0.40)	$ (0.93)	$ (1.23)
Net loss per share — diluted (in USD per share)	$ (0.33)	$ (0.40)	$ (0.93)	$ (1.23)
Weighted-average common shares used to compute net loss per share - basic (in shares)	100,999	99,475	100,693	99,027
Weighted-average common shares used to compute net loss per share - diluted (in shares)	100,999	99,475	100,693	99,027

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders’ Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss)/Income	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2021		98,381
Beginning balance at Dec. 31, 2021	$ 316,185	$ 10	$ 964,965	$ (714)	$ (648,076)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	5,381		5,381
Common stock issued upon exercise of stock options (in shares)		15
Common stock issued upon exercise of stock options	3		3
Common stock issued upon release of restricted stock units (in shares)		371
Restricted stock surrendered for taxes (in shares)		0
Foreign currency translation adjustments	14			14
Unrealized gain (loss) on marketable securities	(723)			(723)
Net loss	(37,908)				(37,908)
Ending balance (in shares) at Mar. 31, 2022		98,767
Ending balance at Mar. 31, 2022	282,952	$ 10	970,349	(1,423)	(685,984)
Beginning balance (in shares) at Dec. 31, 2021		98,381
Beginning balance at Dec. 31, 2021	316,185	$ 10	964,965	(714)	(648,076)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustments	(50)
Unrealized gain (loss) on marketable securities	(1,189)
Net loss	(121,800)
Ending balance (in shares) at Sep. 30, 2022		99,728
Ending balance at Sep. 30, 2022	208,337	$ 10	980,156	(1,953)	(769,876)
Beginning balance (in shares) at Mar. 31, 2022		98,767
Beginning balance at Mar. 31, 2022	282,952	$ 10	970,349	(1,423)	(685,984)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	4,942		4,942
Common stock issued upon release of restricted stock units (in shares)		5
Common stock issued under employee stock purchase plan (in shares)		499
Common stock issued under employee stock purchase plan	362		362
Foreign currency translation adjustments	(34)			(34)
Unrealized gain (loss) on marketable securities	(339)			(339)
Net loss	(43,761)				(43,761)
Ending balance (in shares) at Jun. 30, 2022		99,271
Ending balance at Jun. 30, 2022	244,122	$ 10	975,653	(1,796)	(729,745)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	4,503		4,503
Common stock issued upon release of restricted stock units (in shares)		457
Foreign currency translation adjustments	(30)			(30)
Unrealized gain (loss) on marketable securities	(127)			(127)
Net loss	(40,131)				(40,131)
Ending balance (in shares) at Sep. 30, 2022		99,728
Ending balance at Sep. 30, 2022	208,337	$ 10	980,156	(1,953)	(769,876)
Beginning balance (in shares) at Dec. 31, 2022		100,117
Beginning balance at Dec. 31, 2022	181,518	$ 10	985,651	(1,531)	(802,612)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	4,563		4,563
Common stock issued upon release of restricted stock units (in shares)		456
Foreign currency translation adjustments	(7)			(7)
Unrealized gain (loss) on marketable securities	739			739
Net loss	(29,056)				(29,056)
Ending balance (in shares) at Mar. 31, 2023		100,573
Ending balance at Mar. 31, 2023	157,757	$ 10	990,214	(799)	(831,668)
Beginning balance (in shares) at Dec. 31, 2022		100,117
Beginning balance at Dec. 31, 2022	$ 181,518	$ 10	985,651	(1,531)	(802,612)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issued upon exercise of stock options (in shares)	1
Foreign currency translation adjustments	$ (24)
Unrealized gain (loss) on marketable securities	1,003
Net loss	(93,451)
Ending balance (in shares) at Sep. 30, 2023		101,027
Ending balance at Sep. 30, 2023	102,714	$ 10	999,319	(552)	(896,063)
Beginning balance (in shares) at Mar. 31, 2023		100,573
Beginning balance at Mar. 31, 2023	157,757	$ 10	990,214	(799)	(831,668)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	4,469		4,469
Common stock issued upon release of restricted stock units (in shares)		2
Common stock issued under employee stock purchase plan (in shares)		418
Common stock issued under employee stock purchase plan	246		246
Foreign currency translation adjustments	(5)			(5)
Unrealized gain (loss) on marketable securities	198			198
Net loss	(31,510)				(31,510)
Ending balance (in shares) at Jun. 30, 2023		100,993
Ending balance at Jun. 30, 2023	131,155	$ 10	994,929	(606)	(863,178)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	4,389		4,389
Common stock issued upon exercise of stock options (in shares)		1
Common stock issued upon exercise of stock options	1		1
Common stock issued upon release of restricted stock units (in shares)		33
Foreign currency translation adjustments	(12)			(12)
Unrealized gain (loss) on marketable securities	66			66
Net loss	(32,885)				(32,885)
Ending balance (in shares) at Sep. 30, 2023		101,027
Ending balance at Sep. 30, 2023	$ 102,714	$ 10	$ 999,319	$ (552)	$ (896,063)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net loss	$ (93,451)	$ (121,800)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	4,635	4,816
Stock-based compensation expense	13,421	14,826
Net accretion of discount on marketable securities	(1,835)	(277)
Non-cash lease expense	12,466	3,092
Loss on disposal of property and equipment	85	101
Impairment of long-lived assets	0	2,011
Other	(257)	(1,526)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(923)	(3,468)
Other assets	143	864
Accounts payable	(62)	(543)
Accrued expenses and other liabilities	(1,452)	(217)
Lease liability and lease incentive receivable	(2,344)	12,505
Net cash used in operating activities	(69,574)	(89,616)
Cash flows from investing activities:
Purchases of marketable securities	(20,232)	(81,782)
Maturities of marketable securities	127,601	232,899
Purchases of property and equipment	(616)	(11,631)
Net cash provided by investing activities	106,753	139,486
Cash flows from financing activities:
Proceeds from issuance of common stock pursuant to option exercises	1	3
Payment of deferred offering costs	(344)	0
Proceeds from employee stock purchase plan	246	362
Net cash (used in) provided by financing activities	(97)	365
Net increase in cash and cash equivalents and restricted cash	37,082	50,235
Cash and cash equivalents and restricted cash at beginning of period	70,934	36,698
Cash and cash equivalents and restricted cash at end of period	108,016	86,933
Cash and cash equivalents	105,366	84,430
Restricted cash	2,650	2,503
Cash and cash equivalents and restricted cash at end of period	108,016	86,933
Supplemental schedule of noncash investing and financing information
Non-cash settlement of operating lease liability	14,903	0
Remeasurement of operating lease right-of-use assets	13,711	2,842
Fixed assets in accounts payable, accrued expenses and other current liabilities	0	168
Deferred offering costs included in accounts payable	$ 58	$ 0

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Adverum Biotechnologies, Inc. (the “Company” or “Adverum”) was incorporated in Delaware on July 17, 2006 and is headquartered in Redwood City, California. The Company aims to establish gene therapy as a new standard of care for highly prevalent ocular diseases. The Company develops gene therapy product candidates intended to provide durable efficacy by inducing sustained expression of a therapeutic protein. The Company has not generated any revenue from the sale of products since its inception. The Company has experienced net losses since its inception and had an accumulated deficit of $896.1 million as of September 30, 2023. The Company expects to incur losses and have negative net cash flows from operating activities as it engages in further research and development activities. As of September 30, 2023, the Company had cash, cash equivalents and short-term investments of $117.1 million, which the Company believes will be sufficient to fund its operations for at least twelve months from the date of issuance of these financial statements. Basis of Presentation — The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and follow the requirements of the Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These unaudited condensed consolidated financial statements have been prepared on the same basis as the Company’s annual consolidated financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair statement of the Company’s consolidated financial information. The results of operations for the three and nine months ended September 30, 2023 are not necessarily indicative of the results to be expected for the full year or any other future period. The balance sheet as of December 31, 2022 is derived from the audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete consolidated financial statements. The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 filed with the SEC. Liquidity, Risks and Uncertainties As of September 30, 2023, the Company has devoted substantially all of its efforts to product development and has not realized product sales revenues from its planned principal operations. The Company has a limited operating history, and the sales and income potential of the Company’s business and market are unproven. The Company has experienced net losses since its inception and, as of September 30, 2023, had an accumulated deficit of $896.1 million. The Company expects to continue to incur net losses and operating cash outflows for at least the next several years. A successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. The Company will need to raise additional capital through equity or debt financings, collaborative or other arrangements with corporate sources or through other sources of financing. The Company may be unable to raise additional funds or to enter into such agreements or arrangements on favorable terms, or at all. If the Company is unable to raise capital or enter into such agreements as and when needed, it may have to significantly delay, scale back or discontinue the development or commercialization of one or more of its product candidates. As of September 30, 2023, the Company had cash, cash equivalents and short-term investments of $117.1 million, which is sufficient to fund our operations into 2025.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Use of Estimates The accompanying condensed consolidated financial statements have been prepared in accordance with U.S. GAAP. The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities and the reported amounts of expenses in the condensed consolidated financial statements and the accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accruals, fair value of assets and liabilities, impairment of long-lived assets, income taxes, and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates. Accrued Interest Receivable Accrued interest receivable related to the Company’s available-for-sale debt securities is presented within prepaid expenses and other current assets on the Company’s condensed consolidated balance sheets. The Company has elected to exclude accrued interest receivable from both the fair value and the amortized cost basis of available-for-sale debt securities for the purposes of identifying and measuring any impairment. The Company writes off accrued interest receivable once it has determined that the asset is not realizable. Any write offs of accrued interest receivable are recorded by reversing interest income, recognizing credit loss expense, or a combination of both. To date, the Company has not written off any accrued interest receivables associated with its available-for-sale debt securities. Recently Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments (“ Topic 326 ”) and also issued subsequent amendments to the initial guidance: ASU 2018-19, ASU 2019-04, ASU 2019-05, and ASU 2019-11. The standard requires that financial assets measured at amortized cost be presented at the net amount expected to be collected. The measurement of expected credit losses is based on historical experience, current conditions, and reasonable and supportable forecasts that affect collectability. Topic 326 also eliminates the concept of “other-than-temporary” impairment when evaluating available-for-sale debt securities and instead focuses on determining whether any impairment is a result of a credit loss or other factors. An entity will recognize an allowance for credit losses on available-for-sale debt securities rather than an other-than-temporary impairment that reduces the cost basis of the investment. The Company adopted ASU 2016-13 on January 1, 2023, using the modified retrospective approach. The adoption of ASU 2016-13 had no significant impact on the Company’s condensed consolidated financial statements.

Fair Value Measurements and Fai

Fair Value Measurements and Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements and Fair Value of Financial Instruments	Fair Value Measurements and Fair Value of Financial Instruments The authoritative guidance on the fair value hierarchy for disclosure of fair value measurements is as follows: Level 1 : Quoted prices in active markets for identical assets or liabilities. Level 2 : Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 : Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The fair value of Level 1 securities is determined using quoted prices in active markets for identical assets. Level 1 securities consist of highly liquid money market funds. Financial assets and liabilities are considered Level 2 when their fair values are determined using inputs that are observable in the market or can be derived principally from or corroborated by observable market data such as pricing for similar securities, recently executed transactions, cash flow models with yield curves, and benchmark securities. In addition, Level 2 financial instruments are valued using comparisons to like-kind financial instruments and models that use readily observable market data as their basis. U.S. government and agency securities, commercial paper, and corporate bonds are valued primarily using market prices of comparable securities, bid/ask quotes, interest rate yields and prepayment spreads and are included in Level 2. The following is a summary of the Company’s cash equivalents and short-term investments: September 30, 2023 Amortized Cost Basis Unrealized Gains Unrealized Estimated Fair Value (In thousands) Level 1: Money market funds $ 10,140 $ — $ — $ 10,140 Level 2: Commercial paper 91,259 — (31) 91,228 U.S. government and agency securities 11,786 — (71) 11,715 Total cash equivalents and short-term investments 113,185 — (102) 113,083 Less: cash equivalents (101,399) — 32 (101,367) Total short-term investments $ 11,786 $ — $ (70) $ 11,716 December 31, 2022 Amortized Cost Basis Unrealized Gains Unrealized Estimated Fair Value (In thousands) Level 1: Money market funds $ 10,235 $ — $ — $ 10,235 Level 2: Commercial paper 102,722 — (246) 102,476 U.S. government and agency securities 59,487 — (824) 58,663 Corporate bonds 2,059 — (35) 2,024 Total cash equivalents and short-term investments 174,503 — (1,105) 173,398 Less: cash equivalents (56,256) — 16 (56,240) Total short-term investments $ 118,247 $ — $ (1,089) $ 117,158 As of September 30, 2023, all marketable securities have a remaining maturity of less than one year. The aggregate fair value of debt securities in an unrealized loss position at September 30, 2023 and December 31, 2022 was $102.9 million and $155.5 million, respectively, which are highly liquid funds with high credit ratings that have final maturity of less than two years from date of purchase. The Company has not recorded an allowance for credit losses as of September 30, 2023 and December 31, 2022 related to these securities. The accrued interest receivable on available-for-sale marketable securities was immaterial at September 30, 2023 and December 31, 2022. The Company held 24 securities that were in unrealized loss positions as of September 30, 2023. There were no individual securities that were in a significant unrealized loss position as of September 30, 2023 and December 31, 2022. The Company regularly reviews the securities in an unrealized loss position and evaluates the current expected credit loss by considering factors such as historical experience, market data, issuer-specific factors, and current economic conditions. The Company does not intend to sell the investments and it is not more likely than not that the Company will be required to sell the investments before recovery of their amortized cost bases. The Company has not recorded any impairment charges on available-for-sale securities.

License Revenue

License Revenue	9 Months Ended
	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
License Revenue	License Revenue Lexeo - On January 25, 2021, the Company and Lexeo Therapeutics, Inc (“Lexeo”) entered into a License Agreement pursuant to which the Company granted Lexeo an exclusive, worldwide, royalty-bearing license to certain of the Company’s intellectual property to develop, manufacture, and commercialize a gene therapy product to treat cardiomyopathy due to Friedreich’s Ataxia. Under the terms of the agreement, the Company is eligible to receive additional payments upon the achievement of certain milestones. Additionally, the Company will receive royalty payments on net sales subject to a cap and reductions based on patent expiry, anti-stacking, and a defined royalty floor percentage. In February 2023, Lexeo notified the Company that it achieved the first development milestone; accordingly the Company is eligible to receive additional payments. Therefore, the Company recognized $3.5 million of license revenue during the nine months ended September 30, 2023.

Leases

Leases	9 Months Ended
	Sep. 30, 2023
Leases [Abstract]
Leases	Leases Redwood City, California The Company has a lease for facilities in Redwood City, California (“Redwood City Premises”), which expires December 31, 2031, with option to extend for a period of eight years. Related to this lease, the Company provided the landlord with a letter of credit in the amount of $2.7 million as of September 30, 2023, which is classified as restricted cash under long term assets on the Company’s condensed consolidated balance sheets. In October 2023, the Company entered into an amendment to the letter of credit reducing the amount to $1.9 million. In March 2023, the Company entered into an amendment to accelerate the expiration of one of the facilities in its Redwood City Premises from December 31, 2031 to September 30, 2023. Concurrently, the Company entered into an agreement for additional tenant improvement allowance towards its other Redwood City Premises. As a result of the modification the Company revalued the lease liability based on the new and remaining lease terms, which resulted in a reduction to the lease liability of $8.3 million, and recognized the remeasurement to the lease liabilities as an adjustment to the right-of-use asset. The estimated value of non-cash consideration, composed primarily of leasehold improvements and furniture and fixtures, was $14.9 million, which was fully amortized as of September 30, 2023. Durham, North Carolina The Company has an operating lease agreement for a building in Durham, North Carolina (“NC Premises”). The lease commenced in April 2021 when the Company obtained control of the NC Premises, and the lease term expires in October 2037 with two options to extend the lease term for a period of five years each. In April 2023, the Company entered into an amendment to reduce the rent payments for the NC Premises, effective as of May 1, 2023. On October 26, 2021, the Company entered into a sublease agreement with a subtenant for the NC Premises through October 2037, the remainder of the lease term. In line with the amendment to the NC Premises’ lease, sublease rent payments were correspondingly reduced. Sublease income for operating leases is recognized on a cash basis over the lease term based on assessment of probability of collection. In September 2022, the Company assessed the collectability of sublease income receivable to be less than probable and recognized an adjustment to eliminate the deferred rent receivable as an adjustment to sublease income, resulting in an increase in general and administrative expenses in the three and nine month periods ended September 30, 2022. As a result of the adjustment to eliminate the deferred rent receivable, sublease income for the three and nine months ended September 30, 2022 was a negative $4.1 million and $0.8 million, respectively. Sublease income was $1.3 million and $4.1 million for the three and nine months ended September 30, 2023, respectively. The sublease income is classified as a reduction of rent expense in operating expenses. As of September 30, 2023, undiscounted future non-cancellable lease payments under the lease agreements are as follows (in thousands): Year ending December 31, Operating Leases Sublease Payments Receivable 2023 (remaining three months) $ 2,696 $ 1,286 2024 11,086 5,248 2025 11,448 5,405 2026 11,821 5,568 2027 12,207 5,735 Thereafter 94,653 66,416 Total undiscounted lease payments $ 143,911 $ 89,658 Less: Present value adjustments $ (68,387) Total lease liability $ 75,524

Balance Sheet Components

Balance Sheet Components	9 Months Ended
	Sep. 30, 2023
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	Balance Sheet Components Property and Equipment, Net Property and equipment, net consists of the following: September 30, 2023 December 31, 2022 (In thousands) Laboratory equipment $ 14,452 $ 14,382 Leasehold improvements 13,586 34,336 Computer equipment and software 868 1,325 Furniture and fixtures — 868 Construction in progress 93 1,010 Total property and equipment 28,999 51,921 Less accumulated depreciation and amortization (13,502) (16,994) Property and equipment, net $ 15,497 $ 34,927 Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consist of the following: September 30, 2023 December 31, 2022 (In thousands) Employee compensation $ 7,281 $ 8,710 Accrued nonclinical, clinical and process development costs 6,728 6,854 Accrued professional services 588 532 State income tax payable 102 254 Other 1,663 417 Total accrued expenses and other current liabilities $ 16,362 $ 16,767

Equity Incentive Awards

Equity Incentive Awards	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Equity Incentive Awards	Equity Incentive Awards Stock Options The following table summarizes the Company’s option activity and related information: Number of Weighted- Balance at December 31, 2022 19,320 $ 5.79 Options granted 6,056 1.05 Options exercised (1) 1.29 Options forfeited (1,314) 3.05 Balance at September 30, 2023 24,061 $ 4.74 Exercisable as of September 30, 2023 9,724 $ 8.54 Restricted Stock Units (“RSUs”) The following table summarizes the Company’s RSUs activity and related information: Number of Units Weighted- Outstanding at December 31, 2022 1,693 $ 2.90 Granted 539 0.77 Vested and released (491) 3.14 Forfeited (128) 1.94 Outstanding at September 30, 2023 1,613 $ 2.20 Stock-Based Compensation Expense The following table presents, by operating expense, the Company’s stock-based compensation expense: Three Months Ended Nine Months Ended 2023 2022 2023 2022 (In thousands) Research and development $ 1,164 $ 1,432 $ 3,925 $ 5,195 General and administrative 3,225 3,071 9,496 9,631 Total stock-based compensation expense $ 4,389 $ 4,503 $ 13,421 $ 14,826

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Net Loss per Share	Net Loss per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock outstanding for the period. Diluted net loss per share is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period using the treasury stock method. Outstanding stock options, RSUs, rights under the employee stock purchase plan (“ESPP”) and warrants are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. The following common stock equivalents outstanding at the end of the periods presented were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: September 30, 2023 September 30, 2022 (In thousands) Stock options 24,062 19,221 Restricted stock units 1,613 1,724 ESPP 394 760 26,069 21,705

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation — The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) and follow the requirements of the Securities and Exchange Commission (“SEC”) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by U.S. GAAP can be condensed or omitted. These unaudited condensed consolidated financial statements have been prepared on the same basis as the Company’s annual consolidated financial statements and, in the opinion of management, reflect all adjustments, consisting only of normal recurring adjustments, which are necessary for a fair statement of the Company’s consolidated financial information. The results of operations for the three and nine months ended September 30, 2023 are not necessarily indicative of the results to be expected for the full year or any other future period. The balance sheet as of December 31, 2022 is derived from the audited consolidated financial statements at that date but does not include all of the information required by U.S. GAAP for complete consolidated financial statements. The accompanying unaudited condensed consolidated financial statements and related financial information should be read in conjunction with the audited consolidated financial statements and the related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022 filed with the SEC.
Liquidity, Risks and Uncertainties	Liquidity, Risks and Uncertainties As of September 30, 2023, the Company has devoted substantially all of its efforts to product development and has not realized product sales revenues from its planned principal operations. The Company has a limited operating history, and the sales and income potential of the Company’s business and market are unproven. The Company has experienced net losses since its inception and, as of September 30, 2023, had an accumulated deficit of $896.1 million. The Company expects to continue to incur net losses and operating cash outflows for at least the next several years. A successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. The Company will need to raise additional capital through equity or debt financings, collaborative or other arrangements with corporate sources or through other sources of financing. The Company may be unable to raise additional funds or to enter into such agreements or arrangements on favorable terms, or at all. If the Company is unable to raise capital or enter into such agreements as and when needed, it may have to significantly delay, scale back or discontinue the development or commercialization of one or more of its product candidates. As of September 30, 2023, the Company had cash, cash equivalents and short-term investments of $117.1 million, which is sufficient to fund our operations into 2025.
Use of Estimates	Use of Estimates The accompanying condensed consolidated financial statements have been prepared in accordance with U.S. GAAP. The preparation of the condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent liabilities and the reported amounts of expenses in the condensed consolidated financial statements and the accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to clinical trial accruals, fair value of assets and liabilities, impairment of long-lived assets, income taxes, and stock-based compensation. Management bases its estimates on historical experience and on various other market-specific and relevant assumptions that management believes to be reasonable under the circumstances. Actual results could differ from those estimates.
Accrued Interest Receivable	Accrued Interest Receivable Accrued interest receivable related to the Company’s available-for-sale debt securities is presented within prepaid expenses and other current assets on the Company’s condensed consolidated balance sheets. The Company has elected to exclude accrued interest receivable from both the fair value and the amortized cost basis of available-for-sale debt securities for the purposes of identifying and measuring any impairment. The Company writes off accrued interest receivable once it has determined that the asset is not realizable. Any write offs of accrued interest receivable are recorded by reversing interest income, recognizing credit loss expense, or a combination of both. To date, the Company has not written off any accrued interest receivables associated with its available-for-sale debt securities.
Recently Adopted Accounting Pronouncements	Recently Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments (“ Topic 326 ”) and also issued subsequent amendments to the initial guidance: ASU 2018-19, ASU 2019-04, ASU 2019-05, and ASU 2019-11. The standard requires that financial assets measured at amortized cost be presented at the net amount expected to be collected. The measurement of expected credit losses is based on historical experience, current conditions, and reasonable and supportable forecasts that affect collectability. Topic 326 also eliminates the concept of “other-than-temporary” impairment when evaluating available-for-sale debt securities and instead focuses on determining whether any impairment is a result of a credit loss or other factors. An entity will recognize an allowance for credit losses on available-for-sale debt securities rather than an other-than-temporary impairment that reduces the cost basis of the investment. The Company adopted ASU 2016-13 on January 1, 2023, using the modified retrospective approach. The adoption of ASU 2016-13 had no significant impact on the Company’s condensed consolidated financial statements.

Fair Value Measurements and F_2

Fair Value Measurements and Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Schedule of Cash Equivalents and Short-term Investments	The following is a summary of the Company’s cash equivalents and short-term investments: September 30, 2023 Amortized Cost Basis Unrealized Gains Unrealized Estimated Fair Value (In thousands) Level 1: Money market funds $ 10,140 $ — $ — $ 10,140 Level 2: Commercial paper 91,259 — (31) 91,228 U.S. government and agency securities 11,786 — (71) 11,715 Total cash equivalents and short-term investments 113,185 — (102) 113,083 Less: cash equivalents (101,399) — 32 (101,367) Total short-term investments $ 11,786 $ — $ (70) $ 11,716 December 31, 2022 Amortized Cost Basis Unrealized Gains Unrealized Estimated Fair Value (In thousands) Level 1: Money market funds $ 10,235 $ — $ — $ 10,235 Level 2: Commercial paper 102,722 — (246) 102,476 U.S. government and agency securities 59,487 — (824) 58,663 Corporate bonds 2,059 — (35) 2,024 Total cash equivalents and short-term investments 174,503 — (1,105) 173,398 Less: cash equivalents (56,256) — 16 (56,240) Total short-term investments $ 118,247 $ — $ (1,089) $ 117,158

Leases (Tables)

Leases (Tables)	9 Months Ended
	Sep. 30, 2023
Leases [Abstract]
Schedule of Undiscounted Future Lease Payments under Operating Lease	As of September 30, 2023, undiscounted future non-cancellable lease payments under the lease agreements are as follows (in thousands): Year ending December 31, Operating Leases Sublease Payments Receivable 2023 (remaining three months) $ 2,696 $ 1,286 2024 11,086 5,248 2025 11,448 5,405 2026 11,821 5,568 2027 12,207 5,735 Thereafter 94,653 66,416 Total undiscounted lease payments $ 143,911 $ 89,658 Less: Present value adjustments $ (68,387) Total lease liability $ 75,524
Schedule of Undiscounted Future Sublease Payments Receivable under Operating Lease	As of September 30, 2023, undiscounted future non-cancellable lease payments under the lease agreements are as follows (in thousands): Year ending December 31, Operating Leases Sublease Payments Receivable 2023 (remaining three months) $ 2,696 $ 1,286 2024 11,086 5,248 2025 11,448 5,405 2026 11,821 5,568 2027 12,207 5,735 Thereafter 94,653 66,416 Total undiscounted lease payments $ 143,911 $ 89,658 Less: Present value adjustments $ (68,387) Total lease liability $ 75,524

Balance Sheet Components (Table

Balance Sheet Components (Tables)	9 Months Ended
	Sep. 30, 2023
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consists of the following: September 30, 2023 December 31, 2022 (In thousands) Laboratory equipment $ 14,452 $ 14,382 Leasehold improvements 13,586 34,336 Computer equipment and software 868 1,325 Furniture and fixtures — 868 Construction in progress 93 1,010 Total property and equipment 28,999 51,921 Less accumulated depreciation and amortization (13,502) (16,994) Property and equipment, net $ 15,497 $ 34,927
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following: September 30, 2023 December 31, 2022 (In thousands) Employee compensation $ 7,281 $ 8,710 Accrued nonclinical, clinical and process development costs 6,728 6,854 Accrued professional services 588 532 State income tax payable 102 254 Other 1,663 417 Total accrued expenses and other current liabilities $ 16,362 $ 16,767

Equity Incentive Awards (Tables

Equity Incentive Awards (Tables)	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of Stock Options Activity	The following table summarizes the Company’s option activity and related information: Number of Weighted- Balance at December 31, 2022 19,320 $ 5.79 Options granted 6,056 1.05 Options exercised (1) 1.29 Options forfeited (1,314) 3.05 Balance at September 30, 2023 24,061 $ 4.74 Exercisable as of September 30, 2023 9,724 $ 8.54
Schedule of Restricted Stock Units Activity	The following table summarizes the Company’s RSUs activity and related information: Number of Units Weighted- Outstanding at December 31, 2022 1,693 $ 2.90 Granted 539 0.77 Vested and released (491) 3.14 Forfeited (128) 1.94 Outstanding at September 30, 2023 1,613 $ 2.20
Schedule of Stock-Based Compensation Expense	The following table presents, by operating expense, the Company’s stock-based compensation expense: Three Months Ended Nine Months Ended 2023 2022 2023 2022 (In thousands) Research and development $ 1,164 $ 1,432 $ 3,925 $ 5,195 General and administrative 3,225 3,071 9,496 9,631 Total stock-based compensation expense $ 4,389 $ 4,503 $ 13,421 $ 14,826

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following common stock equivalents outstanding at the end of the periods presented were excluded from the calculation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: September 30, 2023 September 30, 2022 (In thousands) Stock options 24,062 19,221 Restricted stock units 1,613 1,724 ESPP 394 760 26,069 21,705

Organization and Basis of Pre_2

Organization and Basis of Presentation (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ 896,063	$ 802,612
Cash, cash equivalents, and short-term investments	$ 117,100

Fair Value Measurements and F_3

Fair Value Measurements and Fair Value of Financial Instruments - Summary of Cash Equivalents and Short-term Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	$ 11,786	$ 118,247
Unrealized Gains	0	0
Unrealized Losses	(70)	(1,089)
Estimated Fair Value	11,716	117,158
Less: cash equivalents, amortized cost basis	(101,399)	(56,256)
Less: cash equivalents, unrealized gains	0	0
Less: cash equivalents, unrealized losses	32	16
Less: cash equivalents, estimated fair value	(101,367)	(56,240)
Money market funds | Level 1:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	10,140	10,235
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	10,140	10,235
Commercial paper | Level 2:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	91,259	102,722
Unrealized Gains	0	0
Unrealized Losses	(31)	(246)
Estimated Fair Value	91,228	102,476
U.S. government and agency securities | Level 2:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	11,786	59,487
Unrealized Gains	0	0
Unrealized Losses	(71)	(824)
Estimated Fair Value	11,715	58,663
Corporate bonds | Level 2:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis		2,059
Unrealized Gains		0
Unrealized Losses		(35)
Estimated Fair Value		2,024
Total cash equivalents and short-term investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	113,185	174,503
Unrealized Gains	0	0
Unrealized Losses	(102)	(1,105)
Estimated Fair Value	$ 113,083	$ 173,398

Fair Value Measurements and F_4

Fair Value Measurements and Fair Value of Financial Instruments - Additional Information (Details) $ in Millions	Sep. 30, 2023 USD ($) security	Dec. 31, 2022 USD ($)
Fair Value Disclosures [Abstract]
Marketable securities in an unrealized loss | $	$ 102.9	$ 155.5
Number of securities, unrealized loss position | security	24

License Revenue (Details)

License Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Disaggregation of Revenue [Line Items]
License revenue	$ 0	$ 0	$ 3,600	$ 0
Lexeo Therapeutics, Inc
Disaggregation of Revenue [Line Items]
License revenue			$ 3,500

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) contract	Sep. 30, 2022 USD ($)	Oct. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Lessee, Lease, Description [Line Items]
Restricted cash		$ 2,650	$ 2,503	$ 2,650	$ 2,503		$ 2,503
Reduction in lease liability	$ 8,300
Non-cash settlement of operating lease liability		14,903	0	14,903	0
Sublease income		1,300	$ (4,100)	4,100	$ (800)
Letter of Credit
Lessee, Lease, Description [Line Items]
Letter of credit		2,700		2,700
Letter of Credit | Subsequent Event
Lessee, Lease, Description [Line Items]
Letter of credit						$ 1,900
Building
Lessee, Lease, Description [Line Items]
Restricted cash		$ 2,700		$ 2,700
Building | Subsequent Event
Lessee, Lease, Description [Line Items]
Restricted cash						$ 1,900
CALIFORNIA | Building
Lessee, Lease, Description [Line Items]
Lease renewal term		8 years		8 years
NORTH CAROLINA | Manufacturing Facility
Lessee, Lease, Description [Line Items]
Lease renewal term		5 years		5 years
Number of renewal contracts | contract				2

Leases - Schedule of Undiscount

Leases - Schedule of Undiscounted Future Lease Payments under Operating Lease (Detail) $ in Thousands	Sep. 30, 2023 USD ($)
Operating Leases
2023 (remaining three months)	$ 2,696
2024	11,086
2025	11,448
2026	11,821
2027	12,207
Thereafter	94,653
Total undiscounted lease payments	143,911
Less: Present value adjustments	(68,387)
Total lease liability	75,524
Sublease Payments Receivable
2023 (remaining three months)	1,286
2024	5,248
2025	5,405
2026	5,568
2027	5,735
Thereafter	66,416
Total undiscounted lease payments	$ 89,658

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 28,999	$ 51,921
Less accumulated depreciation and amortization	(13,502)	(16,994)
Property and equipment, net	15,497	34,927
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	14,452	14,382
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	13,586	34,336
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment	868	1,325
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	0	868
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 93	$ 1,010

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Balance Sheet Related Disclosures [Abstract]
Employee compensation	$ 7,281	$ 8,710
Accrued nonclinical, clinical and process development costs	6,728	6,854
Accrued professional services	588	532
State income tax payable	102	254
Other	1,663	417
Total accrued expenses and other current liabilities	$ 16,362	$ 16,767

Equity Incentive Awards - Summa

Equity Incentive Awards - Summary of Stock Options Activity (Details) - $ / shares shares in Thousands	9 Months Ended
	Sep. 30, 2023
Number of Options (in thousands)
Beginning balance (in shares)	19,320
Options granted (in shares)	6,056
Options exercised (in shares)	(1)
Options forfeited (in shares)	(1,314)
Ending balance (in shares)	24,061
Exercisable (in shares)	9,724
Weighted- Average Grant- Date Fair Value
Beginning balance (in USD per share)	$ 5.79
Options granted (in USD per share)	1.05
Options exercised (in USD per share)	1.29
Options forfeited (in USD per share)	3.05
Ending balance (in USD per share)	4.74
Exercisable (in USD per share)	$ 8.54

Equity Incentive Awards - Sum_2

Equity Incentive Awards - Summary of Restricted Stock Units Activity (Details) - Restricted stock units shares in Thousands	9 Months Ended
	Sep. 30, 2023 $ / shares shares
Number of Units (in thousands)
Beginning balance (in shares) | shares	1,693
Granted (in shares) | shares	539
Vested and released (in shares) | shares	(491)
Forfeited (in shares) | shares	(128)
Ending balance (in shares) | shares	1,613
Weighted- Average Grant- Date Fair Value
Beginning balance (in USD per share) | $ / shares	$ 2.90
Granted (in USD per share) | $ / shares	0.77
Vested and released (in USD per share) | $ / shares	3.14
Forfeited (in USD per share) | $ / shares	1.94
Ending balance (in USD per share) | $ / shares	$ 2.20

Equity Incentive Awards - Sum_3

Equity Incentive Awards - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 4,389	$ 4,503	$ 13,421	$ 14,826
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	1,164	1,432	3,925	5,195
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 3,225	$ 3,071	$ 9,496	$ 9,631

Net Loss per Share (Details)

Net Loss per Share (Details) - shares shares in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (in shares)	26,069	21,705
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (in shares)	24,062	19,221
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (in shares)	1,613	1,724
ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (in shares)	394	760