Adverum Biotechnologies (ADVM) 10-Q 10 Aug 20 2020 Q2 Quarterly report Financial data

Cover Page

Cover Page - shares	6 Months Ended
	Jun. 30, 2020	Aug. 03, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
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	800 Saginaw Drive,
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	Accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		80,656,651
Entity Central Index Key	0001501756
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 27,359	$ 65,897
Short-term investments	252,780	100,138
Prepaid expenses and other current assets	2,542	9,835
Total current assets	282,681	175,870
Operating lease right-of-use assets	20,011	20,963
Property and equipment, net	27,466	24,884
Restricted cash	999	999
Deposit and other long-term assets	19	11
Total assets	331,176	222,727
Current liabilities:
Accounts payable	10,367	4,103
Accrued expenses and other current liabilities	6,666	11,271
Lease liability, current portion	4,221	4,034
Total current liabilities	21,254	19,408
Lease liability, net of current portion	27,258	28,214
Other non-current liabilities	101	148
Total liabilities	48,613	47,770
Stockholders’ equity:
Preferred stock	0	0
Common stock	8	7
Additional paid-in capital	720,288	560,704
Accumulated other comprehensive loss	(598)	(725)
Accumulated deficit	(437,135)	(385,029)
Total stockholders’ equity	282,563	174,957
Total liabilities and stockholders' equity	$ 331,176	$ 222,727

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses:
Research and development	$ 19,177	$ 8,970	$ 33,928	$ 19,101
General and administrative	10,598	7,132	19,638	12,708
Total operating expenses	29,775	16,102	53,566	31,809
Operating loss	(29,775)	(16,102)	(53,566)	(31,809)
Other income, net	575	1,148	1,460	2,366
Net loss	(29,200)	(14,954)	(52,106)	(29,443)
Other comprehensive loss:
Net unrealized gain on marketable securities	194	20	140	23
Foreign currency translation adjustment	41	(4)	(13)	38
Comprehensive loss	$ (28,965)	$ (14,938)	$ (51,979)	$ (29,382)
Net loss per share — basic and diluted (in USD per share)	$ (0.36)	$ (0.23)	$ (0.68)	$ (0.46)
Weighted-average common shares used to compute net loss per share - basic and diluted (in shares)	80,229	63,740	77,010	63,429

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss)/Income	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2018		62,965,000
Beginning balance at Dec. 31, 2018	$ 201,167	$ 6	$ 522,503	$ (799)	$ (320,543)
Stock-based compensation expense	1,762		1,762
Common stock issued upon exercise of stock options (in shares)		119,000
Common stock issued upon exercise of stock options	162		162
Common stock issued upon release of restricted stock units (in shares)		397,000
Restricted stock surrendered for taxes (in shares)		(145,000)
Restricted stock surrendered for taxes	(504)		(504)
Foreign currency translation adjustments	42			42
Unrealized gain (loss) on marketable securities, net	3			3
Net loss	(14,489)				(14,489)
Ending balance (in shares) at Mar. 31, 2019		63,336,000
Ending balance at Mar. 31, 2019	188,143	$ 6	523,923	(754)	(335,032)
Beginning balance (in shares) at Dec. 31, 2018		62,965,000
Beginning balance at Dec. 31, 2018	201,167	$ 6	522,503	(799)	(320,543)
Foreign currency translation adjustments	38
Unrealized gain (loss) on marketable securities, net	23
Net loss	(29,443)
Ending balance (in shares) at Jun. 30, 2019		64,377,000
Ending balance at Jun. 30, 2019	177,740	$ 6	528,458	(738)	(349,986)
Beginning balance (in shares) at Mar. 31, 2019		63,336,000
Beginning balance at Mar. 31, 2019	188,143	$ 6	523,923	(754)	(335,032)
Stock-based compensation expense	2,626		2,626
Issuance of common stock, net of issuance costs (in shares)		20,000
Issuance of common stock, net of issuance costs	134		134
Common stock issued upon exercise of stock options (in shares)		823,000
Common stock issued upon exercise of stock options	2,312		2,312
Common stock issued under employee stock purchase plan (in shares)		51,000
Common stock issued under employee stock purchase plan	163		163
Common stock issued upon release of restricted stock units (in shares)		220,000
Restricted stock surrendered for taxes (in shares)		(73,000)
Restricted stock surrendered for taxes	(700)		(700)
Foreign currency translation adjustments	(4)			(4)
Unrealized gain (loss) on marketable securities, net	20			20
Net loss	(14,954)				(14,954)
Ending balance (in shares) at Jun. 30, 2019		64,377,000
Ending balance at Jun. 30, 2019	177,740	$ 6	528,458	(738)	(349,986)
Beginning balance (in shares) at Dec. 31, 2019		67,329,000
Beginning balance at Dec. 31, 2019	174,957	$ 7	560,704	(725)	(385,029)
Stock-based compensation expense	3,409		3,409
Issuance of common stock, net of issuance costs (in shares)		10,925,000
Issuance of common stock, net of issuance costs	140,873	$ 1	140,872
Common stock issued upon exercise of stock options (in shares)		1,310,000
Common stock issued upon exercise of stock options	$ 9,650		9,650
Common stock issued upon exercise of warrants (in shares)	7,000
Common stock issued upon release of restricted stock units (in shares)		462,000
Restricted stock surrendered for taxes (in shares)		(155,000)
Restricted stock surrendered for taxes	$ (1,922)		(1,922)
Foreign currency translation adjustments	(54)			(54)
Unrealized gain (loss) on marketable securities, net	(54)			(54)
Net loss	(22,906)				(22,906)
Ending balance (in shares) at Mar. 31, 2020		79,878,000
Ending balance at Mar. 31, 2020	303,953	$ 8	712,713	(833)	(407,935)
Beginning balance (in shares) at Dec. 31, 2019		67,329,000
Beginning balance at Dec. 31, 2019	$ 174,957	$ 7	560,704	(725)	(385,029)
Common stock issued upon exercise of stock options (in shares)	1,953,000
Foreign currency translation adjustments	$ (13)
Unrealized gain (loss) on marketable securities, net	140
Net loss	(52,106)
Ending balance (in shares) at Jun. 30, 2020		80,639,000
Ending balance at Jun. 30, 2020	282,563	$ 8	720,288	(598)	(437,135)
Beginning balance (in shares) at Mar. 31, 2020		79,878,000
Beginning balance at Mar. 31, 2020	303,953	$ 8	712,713	(833)	(407,935)
Stock-based compensation expense	4,785		4,785
Issuance of common stock, additional issuance costs	(51)		(51)
Common stock issued upon exercise of stock options (in shares)		643,000
Common stock issued upon exercise of stock options	2,487		2,487
Common stock issued under employee stock purchase plan (in shares)		57,000
Common stock issued under employee stock purchase plan	475		475
Common stock issued upon release of restricted stock units (in shares)		66,000
Restricted stock surrendered for taxes (in shares)		(5,000)
Restricted stock surrendered for taxes	(121)		(121)
Foreign currency translation adjustments	41			41
Unrealized gain (loss) on marketable securities, net	194			194
Net loss	(29,200)				(29,200)
Ending balance (in shares) at Jun. 30, 2020		80,639,000
Ending balance at Jun. 30, 2020	$ 282,563	$ 8	$ 720,288	$ (598)	$ (437,135)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders Equity (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Statement of Stockholders' Equity [Abstract]
Stock issuance costs	$ 332

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities:
Net loss	$ (52,106)	$ (29,443)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,896	846
Stock-based compensation expense	8,194	4,388
Amortization of premium and accrued interest on marketable securities	(429)	(414)
Other	(6)	38
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	7,298	589
Other assets	(8)	(18)
Operating lease right-of-use asset	952	1,078
Accounts payable	6,962	(924)
Accrued expenses and other current liabilities	(2,507)	(2,029)
Lease liability	(769)	1,084
Net cash used in operating activities	(30,523)	(24,805)
Cash flows from investing activities:
Purchases of marketable securities	(319,690)	(70,549)
Maturities of marketable securities	160,900	41,385
Sales of marketable securities	6,748	0
Purchases of property and equipment	(7,328)	(4,683)
Net cash used in investing activities	(159,370)	(33,847)
Cash flows from financing activities:
Proceeds from offerings of common stock, net of issuance costs	140,822	0
Proceeds from issuance of common stock	0	134
Proceeds from issuance of common stock pursuant to option exercises	12,101	2,474
Taxes paid related to net share settlement of restricted stock units	(2,043)	(1,204)
Proceeds from employee stock purchase plan	475	163
Repayment of loan	0	(56)
Net cash provided by financing activities	151,355	1,511
Net decrease in cash and cash equivalents and restricted cash	(38,538)	(57,141)
Cash and cash equivalents and restricted cash at beginning of period	66,896	155,948
Cash and cash equivalents and restricted cash at end of period	28,358	98,807
Supplemental schedule of noncash investing and financing information
Fixed assets in accounts payable, accrued expenses and other current liabilities	$ 2,391	$ 291

Organization and Basis of Prese

Organization and Basis of Presentation	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Adverum Biotechnologies, Inc. (the “Company” or "Adverum") is a clinical-stage gene therapy company targeting unmet medical needs in ocular and rare diseases. The Company develops gene therapy product candidates intended to provide durable efficacy by inducing sustained expression of a therapeutic protein. The Company’s core capabilities include clinical development, novel vector discovery, and in-house manufacturing expertise, specifically in scalable process development, assay development, and current Good Manufacturing Practices (“cGMP”) quality control. Since the Company’s inception, it has devoted its efforts to performing research and development activities, filing patent applications, hiring personnel and raising capital to support these activities. 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 $437.1 million as of June 30, 2020. The Company expects to incur losses and have negative net cash flows from operating activities as it engages in further research and development activities. The Company believes that it has sufficient funds to continue operations into 2022. 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 six months ended June 30, 2020 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, 2019 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 full extent to which the novel coronavirus disease ("COVID-19") pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including expenses and manufacturing, clinical trials and research and development costs, is dependent upon future developments that are highly uncertain at this time. 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, 2019 filed with the SEC.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2020
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, 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. Recent 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. Topic 326 will become effective for the Company beginning after December 15, 2022 and interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact of adopting Topic 326, but does not expect the effect of adoption to be material.

Fair Value Measurements and Fai

Fair Value Measurements and Fair Value of Financial Instruments	6 Months Ended
	Jun. 30, 2020
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, corporate bond and certificates of deposit are valued primarily using market prices of comparable securities, bid/ask quotes, interest rate yields and prepayment spreads and are included in Level 2. In certain cases, where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3 within the valuation hierarchy. The following is a summary of the Company’s cash equivalents and short-term investments: June 30, 2020 Amortized Cost Basis Unrealized Gains Unrealized Estimated Fair Value (In thousands) Level 1: Money market funds $ 5,952 $ — $ — $ 5,952 Level 2: U.S. government and agency securities 222,151 129 (31) 222,249 Commercial paper 46,817 60 — 46,877 Total cash equivalents and short-term investments 274,920 189 (31) 275,078 Less: cash equivalents (22,298) — — (22,298) Total short-term investments $ 252,622 $ 189 $ (31) $ 252,780 December 31, 2019 Amortized Cost Basis Unrealized Gains Unrealized Estimated Fair Value (In thousands) Level 1: Money market funds $ 15,056 $ — $ — $ 15,056 Level 2: U.S. government and agency securities 37,974 14 (2) 37,986 Commercial paper 87,983 8 (8) 87,983 Corporate bonds 10,495 6 — 10,501 Total cash equivalents and short-term investments 151,508 28 (10) 151,526 Less: cash equivalents (51,391) — 3 (51,388) Total short-term investments $ 100,117 $ 28 $ (7) $ 100,138 As of June 30, 2020, $55.7 million of marketable securities had remaining maturities between one

Balance Sheet Components

Balance Sheet Components	6 Months Ended
	Jun. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	Balance Sheet Components Property and Equipment, Net Property and equipment, net consists of the following: June 30, 2020 December 31, 2019 (In thousands) Computer equipment and software $ 824 $ 752 Laboratory equipment 8,382 6,291 Furniture and fixtures 1,263 678 Leasehold improvements 25,282 1,602 Construction in progress — 23,553 Total property and equipment 35,751 32,876 Less accumulated depreciation and amortization (8,285) (7,992) Property and equipment, net $ 27,466 $ 24,884 Depreciation and amortization expense related to property and equipment for the three months ended June 30, 2020 and 2019 was $1.3 million, and $0.4 million, respectively, and for the six months ended June 30, 2020 and 2019 was $1.9 million and $0.8 million, respectively. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consist of the following: June 30, 2020 December 31, 2019 (In thousands) Employee compensation $ 3,248 $ 4,055 Accrued preclinical, clinical and process development costs 1,656 1,973 Accrued professional services 1,197 2,607 Other 565 2,636 Total accrued expenses and other current liabilities $ 6,666 $ 11,271

Equity Incentive Awards

Equity Incentive Awards	6 Months Ended
	Jun. 30, 2020
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, 2019 8,995 $ 7.19 Options granted 3,501 19.35 Options exercised (1,953) 6.20 Options forfeited (576) 10.11 Balance at June 30, 2020 9,967 $ 11.49 Exercisable as of June 30, 2020 3,115 $ 7.89 Restricted Stock Units (“RSUs”) The following table summarizes the Company’s RSUs activity and related information: Number of Units Weighted- Outstanding at December 31, 2019 1,121 $ 4.59 Granted 104 15.75 Vested and released (529) 4.59 Forfeited (94) 7.10 Outstanding at June 30, 2020 602 $ 6.13 Stock-Based Compensation Expense The following table presents, by operating expense, the Company’s stock-based compensation expense: Three Months Ended Six Months Ended 2020 2019 2020 2019 (In thousands) Research and development $ 1,668 $ 845 $ 2,916 $ 1,477 General and administrative 3,117 1,781 5,278 2,911 Total stock-based compensation expense $ 4,785 $ 2,626 $ 8,194 $ 4,388

Net Loss per Share

Net Loss per Share	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Net Loss per Share	Net Loss per ShareBasic 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: June 30, 2020 June 30, 2019 (In thousands) Stock options 9,967 7,888 Restricted stock units 602 1,280 ESPP 11 8 Warrants to purchase common stock 80 90 10,660 9,266

Related Party Transactions

Related Party Transactions	6 Months Ended
	Jun. 30, 2020
Related Party Transactions [Abstract]
Related Party Transactions	Related Party TransactionIn our February 2020 underwritten public offering of common stock, James Scopa, a member of our Board, and Anne Kenner, as Trustees for the James P. Scopa and Anne E. Kenner Family Trust (the “Trust”) purchased on behalf of the Trust 10,000 shares of our common stock at a price of $13.75 per share, the public offering price in our February 2020 underwritten public offering of common stock, for an aggregate purchase price of $0.1 million, payable in cash.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2020
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 six months ended June 30, 2020 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, 2019 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 full extent to which the novel coronavirus disease ("COVID-19") pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including expenses and manufacturing, clinical trials and research and development costs, is dependent upon future developments that are highly uncertain at this time.
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, 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.
Recent Accounting Pronouncements	Recent 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. Topic 326 will become effective for the Company beginning after December 15, 2022 and interim periods within those fiscal years. Early adoption is permitted. The Company is currently evaluating the impact of adopting Topic 326, but does not expect the effect of adoption to be material.

Fair Value Measurements and F_2

Fair Value Measurements and Fair Value of Financial Instruments (Tables)	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Summary of Cash Equivalents and Short-term Investments	The following is a summary of the Company’s cash equivalents and short-term investments: June 30, 2020 Amortized Cost Basis Unrealized Gains Unrealized Estimated Fair Value (In thousands) Level 1: Money market funds $ 5,952 $ — $ — $ 5,952 Level 2: U.S. government and agency securities 222,151 129 (31) 222,249 Commercial paper 46,817 60 — 46,877 Total cash equivalents and short-term investments 274,920 189 (31) 275,078 Less: cash equivalents (22,298) — — (22,298) Total short-term investments $ 252,622 $ 189 $ (31) $ 252,780 December 31, 2019 Amortized Cost Basis Unrealized Gains Unrealized Estimated Fair Value (In thousands) Level 1: Money market funds $ 15,056 $ — $ — $ 15,056 Level 2: U.S. government and agency securities 37,974 14 (2) 37,986 Commercial paper 87,983 8 (8) 87,983 Corporate bonds 10,495 6 — 10,501 Total cash equivalents and short-term investments 151,508 28 (10) 151,526 Less: cash equivalents (51,391) — 3 (51,388) Total short-term investments $ 100,117 $ 28 $ (7) $ 100,138

Balance Sheet Components (Table

Balance Sheet Components (Tables)	6 Months Ended
	Jun. 30, 2020
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consists of the following: June 30, 2020 December 31, 2019 (In thousands) Computer equipment and software $ 824 $ 752 Laboratory equipment 8,382 6,291 Furniture and fixtures 1,263 678 Leasehold improvements 25,282 1,602 Construction in progress — 23,553 Total property and equipment 35,751 32,876 Less accumulated depreciation and amortization (8,285) (7,992) Property and equipment, net $ 27,466 $ 24,884
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consist of the following: June 30, 2020 December 31, 2019 (In thousands) Employee compensation $ 3,248 $ 4,055 Accrued preclinical, clinical and process development costs 1,656 1,973 Accrued professional services 1,197 2,607 Other 565 2,636 Total accrued expenses and other current liabilities $ 6,666 $ 11,271

Equity Incentive Awards (Tables

Equity Incentive Awards (Tables)	6 Months Ended
	Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Summary of Stock Options Activity	The following table summarizes the Company’s option activity and related information: Number of Weighted- Balance at December 31, 2019 8,995 $ 7.19 Options granted 3,501 19.35 Options exercised (1,953) 6.20 Options forfeited (576) 10.11 Balance at June 30, 2020 9,967 $ 11.49 Exercisable as of June 30, 2020 3,115 $ 7.89
Summary 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, 2019 1,121 $ 4.59 Granted 104 15.75 Vested and released (529) 4.59 Forfeited (94) 7.10 Outstanding at June 30, 2020 602 $ 6.13
Stock-Based Compensation Expense	The following table presents, by operating expense, the Company’s stock-based compensation expense: Three Months Ended Six Months Ended 2020 2019 2020 2019 (In thousands) Research and development $ 1,668 $ 845 $ 2,916 $ 1,477 General and administrative 3,117 1,781 5,278 2,911 Total stock-based compensation expense $ 4,785 $ 2,626 $ 8,194 $ 4,388

Net Loss per Share (Tables)

Net Loss per Share (Tables)	6 Months Ended
	Jun. 30, 2020
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: June 30, 2020 June 30, 2019 (In thousands) Stock options 9,967 7,888 Restricted stock units 602 1,280 ESPP 11 8 Warrants to purchase common stock 80 90 10,660 9,266

Organization and Basis of Pre_2

Organization and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ 437,135	$ 385,029

Fair Value Measurements and F_3

Fair Value Measurements and Fair Value of Financial Instruments - Summary of Cash Equivalents and Short-term Investments (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	$ 252,622	$ 100,117
Unrealized Gains	189	28
Unrealized Losses	(31)	(7)
Estimated Fair Value	252,780	100,138
Less: Cash Equivalents, Amortized Cost Basis	(22,298)	(51,391)
Less: Cash equivalents, unrealized gains	0	0
Less: Cash equivalents, unrealized losses	0	(3)
Less: Cash Equivalents, Estimated Fair Value	(22,298)	(51,388)
Money market funds | Quoted Prices in Active Markets (Level 1)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	5,952	15,056
Unrealized Gains	0	0
Unrealized Losses	0	0
Estimated Fair Value	5,952	15,056
U.S. government and agency securities | Significant Other Observable Inputs (Level 2)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	222,151	37,974
Unrealized Gains	129	14
Unrealized Losses	(31)	(2)
Estimated Fair Value	222,249	37,986
Commercial paper | Significant Other Observable Inputs (Level 2)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	46,817	87,983
Unrealized Gains	60	8
Unrealized Losses	0	(8)
Estimated Fair Value	46,877	87,983
Corporate Bonds | Significant Other Observable Inputs (Level 2)
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis		10,495
Unrealized Gains		6
Unrealized Losses		0
Estimated Fair Value		10,501
Total Cash Equivalents and Short-term Investments
Debt Securities, Available-for-sale [Line Items]
Amortized Cost Basis	274,920	151,508
Unrealized Gains	189	28
Unrealized Losses	(31)	(10)
Estimated Fair Value	$ 275,078	$ 151,526

Fair Value Measurements and F_4

Fair Value Measurements and Fair Value of Financial Instruments - Additional Information (Detail)	Jun. 30, 2020USD ($)
Debt Securities, Available-for-sale [Line Items]
Marketable securities	$ 55,700,000
Other than temporary impaired investments	$ 0
Minimum
Debt Securities, Available-for-sale [Line Items]
Marketable securities term	1 year
Maximum
Debt Securities, Available-for-sale [Line Items]
Marketable securities term	2 years

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 35,751	$ 32,876
Less accumulated depreciation and amortization	(8,285)	(7,992)
Property and equipment, net	27,466	24,884
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment	824	752
Laboratory equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	8,382	6,291
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment	1,263	678
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	25,282	1,602
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 0	$ 23,553

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization expense	$ 1,300	$ 400	$ 1,896	$ 846

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Employee compensation	$ 3,248	$ 4,055
Accrued preclinical, clinical and process development costs	1,656	1,973
Accrued professional services	1,197	2,607
Other	565	2,636
Total accrued expenses and other current liabilities	$ 6,666	$ 11,271

Equity Incentive Awards - Summa

Equity Incentive Awards - Summary of Stock Options Activity (Detail) - $ / shares shares in Thousands	6 Months Ended
	Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Options Outstanding [Roll Forward]
Beginning balance (in shares)	8,995
Options granted (in shares)	3,501
Options exercised (in shares)	(1,953)
Options forfeited (in shares)	(576)
Ending balance (in shares)	9,967
Exercisable (in shares)	3,115
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Beginning balance (in USD per share)	$ 7.19
Options granted (in USD per share)	19.35
Options exercised (in USD per share)	6.20
Options forfeited (in USD per share)	10.11
Ending balance (in USD per share)	11.49
Exercisable (in USD per share)	$ 7.89

Equity Incentive Awards - Sum_2

Equity Incentive Awards - Summary of Restricted Stock Units Activity (Detail) - Restricted stock units shares in Thousands	6 Months Ended
	Jun. 30, 2020$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Beginning balance (in shares) | shares	1,121
Granted (in shares) | shares	104
Vested and released (in shares) | shares	(529)
Forfeited (in shares) | shares	(94)
Ending balance (in shares) | shares	602
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Beginning balance (in USD per share) | $ / shares	$ 4.59
Granted (in USD per share) | $ / shares	15.75
Vested and released (in USD per share) | $ / shares	4.59
Forfeited (in USD per share) | $ / shares	7.10
Ending balance (in USD per share) | $ / shares	$ 6.13

Equity Incentive Awards - Stock

Equity Incentive Awards - Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 4,785	$ 2,626	$ 8,194	$ 4,388
Research and development
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	1,668	845	2,916	1,477
General and administrative
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Total stock-based compensation expense	$ 3,117	$ 1,781	$ 5,278	$ 2,911

Net Loss per Share - Additional

Net Loss per Share - Additional Information (Detail) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (in shares)	10,660	9,266
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (in shares)	9,967	7,888
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (in shares)	602	1,280
ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (in shares)	11	8
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from net loss per share (in shares)	80	90

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Feb. 29, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Related Party Transaction [Line Items]
Cash purchase price				$ 0	$ 134
Common Stock
Related Party Transaction [Line Items]
Issuance of common stock (in shares)		10,925,000	20,000
Common Stock | Trust
Related Party Transaction [Line Items]
Issuance of common stock (in shares)	10,000
Share price (in USD per share)	$ 13.75
Cash purchase price	$ 100