Aligos Therapeutics (ALGS) 10-K 23 Mar 21 2020 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Mar. 18, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Registrant Name	Aligos Therapeutics, Inc.
Entity Central Index Key	0001799448
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Well-known Seasoned Issuer	No
Entity Public Float	$ 0
ICFR Auditor Attestation Flag	false
Entity Common Stock, Shares Outstanding		38,143,228
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Title of 12(b) Security	Common Stock, par value, $0.0001 per share
Trading Symbol	ALGS
Security Exchange Name	NASDAQ
Entity File Number	001-39617
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-4724808
Entity Address, Address Line One	One Corporate Drive
Entity Address, Address Line Two	2nd Floor
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	800
Local Phone Number	466-6059
Document Annual Report	true
Document Transition Report	false
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE Portions of the Registrant’s Definitive Proxy Statement relating to the 2021 Annual Meeting of Stockholders, which will be filed with the Securities and Exchange Commission within 120 days after the end of the Registrant’s fiscal year ended December 31, 2020, are incorporated by reference into Part III of this Report.

Consolidated balance sheets

Consolidated balance sheets - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 220,383,000	$ 69,565,000
Restricted cash	560,000	538,000
Short-term investments	23,130,000	48,098,000
Other current assets	5,944,000	2,025,000
Total current assets	250,017,000	120,226,000
Operating lease right-of-use assets	6,901,000	7,570,000
Property and equipment, net	8,007,000	8,517,000
Other assets	377,000	188,000
Long-term investments		10,019,000
Total assets	265,302,000	146,520,000
Current liabilities:
Accounts payable	3,313,000	3,767,000
Accrued liabilities	16,564,000	7,599,000
Operating lease liabilities, current	2,442,000	2,378,000
Finance lease liabilities, current	64,000	74,000
Deferred Revenue from collaborations, current	7,891,000
Total current liabilities	30,274,000	13,818,000
Derivative liabilities		461,000
Convertible preferred stock liabilities		3,174,000
Operating lease liabilities, net of current portion	10,371,000	11,701,000
Finance lease liabilities, net of current portion	130,000	178,000
Long term liabilities	379,000
Deferred revenue from collaborations	4,109,000
Total liabilities	45,263,000	29,332,000
Commitments and contingencies (Note 13)
Stockholders’ equity (deficit):
Common stock, $0.0001 par value; 320,000,000 and 278,000,000 shares authorized as of December 31, 2020 and 2019, respectively; 36,606,247 and 3,927,803 shares issued and outstanding as of December 31, 2020 and 2019, respectively	4,000	0
Additional paid-in capital	394,963,000	1,421,000
Accumulated deficit	(174,740,000)	(66,197,000)
Accumulated other comprehensive income (loss)	(188,000)	(115,000)
Total stockholders’ equity (deficit)	220,039,000	(64,891,000)
Total liabilities, redeemable convertible preferred stock, and stockholders’ equity (deficit)	265,302,000	146,520,000
Preferred Stock
Current liabilities:
Redeemable convertible preferred stock	0	0
Series A
Current liabilities:
Redeemable convertible preferred stock	0	100,695,000
Series B-1
Current liabilities:
Redeemable convertible preferred stock	$ 0	$ 81,384,000

Consolidated balance sheets (Pa

Consolidated balance sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Temporary Equity, Shares Authorized	10,000,000
Temporary Equity, Shares Issued	0
Common Stock, Par Value	$ 0.000001	$ 0.000001
Common Stock, Shares Authorized	320,000,000	278,000,000
Common Stock, Shares, Issued	36,606,247	3,927,803
Common Stock, Shares, Outstanding	36,606,247	3,927,803
Preferred Stock
Temporary Equity, Par Value	$ 0.000001	$ 0.000001
Temporary Equity, Shares Authorized	10,000,000	0
Temporary Equity, Shares Issued	0	0
Temporary Equity, Shares Outstanding	0	0
Series A
Temporary Equity, Par Value	$ 0.000001	$ 0.000001
Temporary Equity, Shares Authorized	0	101,962,864
Temporary Equity, Shares Issued	0	10,819,843
Temporary Equity, Shares Outstanding	0	10,819,843
Temporary Equity, Liquidation Preference		$ 100,838
Series B-1
Temporary Equity, Par Value	$ 0.000001	$ 0.000001
Temporary Equity, Shares Authorized	0	77,764,055
Temporary Equity, Shares Issued	0	8,344,034
Temporary Equity, Shares Outstanding	0	8,344,034
Temporary Equity, Liquidation Preference		$ 85,005

Consolidated statements of oper

Consolidated statements of operations and comprehensive loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development	$ 79,890	$ 44,038
General and administrative	17,944	10,005
Total operating expenses	97,834	54,043
Loss from operations	(97,834)	(54,043)
Interest and other (expense) income, net	(10,548)	1,864
Loss before income tax expense	(108,382)	(52,179)
Income tax expense	(161)	(85)
Net loss	(108,543)	(52,264)
Other comprehensive (loss) and income:
Loss on pension plans	(141)	(118)
Gain on available for sale investments	68
Comprehensive loss	$ (108,616)	$ (52,382)
Net loss per share, basic and diluted	$ (10.87)	$ (26.04)
Weighted average shares of common stock, basic and diluted	9,988,191	2,007,173

Consolidated statements of chan

Consolidated statements of changes in redeemable convertible preferred stock and stockholders' equity (deficit) - USD ($) $ in Thousands	Total	Green House Initial Public Offering	Initial Public Offering	Series A	Series AInitial Public Offering	Series B-1	Series B-1Initial Public Offering	Series B-2	Series B-2Initial Public Offering	Common Stock	Common StockGreen House Initial Public Offering	Common StockInitial Public Offering	Additional Paid-in Capital	Additional Paid-in CapitalGreen House Initial Public Offering	Additional Paid-in CapitalInitial Public Offering	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2018	$ (13,748)												$ 182			$ (13,933)	$ 3
Beginning balance, Shares at Dec. 31, 2018				10,806,432
Beginning balance at Dec. 31, 2018				$ 100,519
Beginning balance, Shares at Dec. 31, 2019				10,819,843		8,344,034
Beginning balance at Dec. 31, 2019				$ 100,695		$ 81,384
Beginning balance, Shares at Dec. 31, 2018										3,036,574
Issuance of common stock upon exercise of stock options	461												461
Issuance of common stock upon exercise of stock options, shares										891,229
Vesting of early exercised common stock	26												26
Issuance of redeemable convertible preferred stock						$ 81,384
Issuance of redeemable convertible preferred stock, shares						8,344,034
Issuance of Series A redeemable convertible stock upon exercise of Series A warrants				$ 176
Issuance of Series A redeemable convertible stock upon exercise of Series A warrants, shares				13,411
Stock-based compensation	752												752
Other comprehensive loss	(118)																(118)
Net loss	(52,264)															(52,264)
Ending balance at Dec. 31, 2019	(64,891)												1,421			(66,197)	(115)
Ending balance, Shares at Dec. 31, 2019										3,927,803
Beginning balance, Shares at Dec. 31, 2020				0		0
Beginning balance at Dec. 31, 2020				$ 0		$ 0
Issuance of common stock upon exercise of stock options	261									$ 0			261
Issuance of common stock upon exercise of stock options, shares										188,594
Vesting of early exercised common stock	363												363
Issuance of redeemable convertible preferred stock								$ 40,000
Issuance of redeemable convertible preferred stock, shares								3,569,630
Reclassification of Series A warrant and convertible preferred stock liabilities to equity				620				$ 14,560
Issuance of Series A redeemable convertible stock upon exercise of Series A warrants				$ 1,262
Issuance of Series A redeemable convertible stock upon exercise of Series A warrants, shares				120,702
Conversion of redeemable convertible preferred stock to common stock			$ 238,523		$ (102,577)		$ (81,384)		$ (54,560)			$ 3			$ 238,520
Conversion of redeemable convertible preferred stock to common stock, shares					(10,940,545)		(8,344,034)		(3,569,630)			22,854,209
Issuance of common stock		$ 16,043	$ 139,500								$ 0	$ 1		$ 16,042	$ 139,499
Issuance of common stock, shares											1,150,000	10,000,000
Costs related to the IPO and Greenshoe	(4,116)												(4,116)
Stock-based compensation	2,975												2,975
Other comprehensive loss	(73)																(73)
Net loss	(108,543)															(108,543)
Ending balance at Dec. 31, 2020	$ 220,039									$ 4			$ 394,963			$ (174,740)	$ (188)
Ending balance, Shares at Dec. 31, 2020										38,120,606

Consolidated statements of ch_2

Consolidated statements of changes in redeemable convertible preferred stock and stockholders' equity (deficit) (Parenthetical) $ in Thousands	Dec. 31, 2019USD ($)
Statement Of Stockholders Equity [Abstract]
Issuance costs	$ 442
Convertible preferred stock liabilities	$ 3,174

Consolidated statements of cash

Consolidated statements of cash flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (108,543)	$ (52,264)
Adjustments to reconcile net loss to net cash used in operating activities:
Accretion of discount on short term investments	234	(877)
Amortization of right of use assets	590	903
Depreciation expense	2,735	1,396
Stock-based compensation	2,975	752
Change in fair value of derivative liability	296	(348)
Change in fair value of convertible preferred stock liabilities	11,387
Changes in operating assets and liabilities:
Other assets	(4,107)	(1,030)
Right of use assets		95
Accounts payable	(130)	385
Accrued liabilities	9,566	4,222
Operating lease liabilities	(1,266)	(1)
Deferred revenue	12,000
Net cash and cash equivalents used in operating activities	(74,263)	(46,767)
Cash flows from investing activities:
Purchases of short-term investments	(32,097)	(60,404)
Purchases of long-term investments	(13,184)	(10,019)
Maturities of short-term investments	80,100	80,000
Purchases of property and equipment	(2,064)	(2,786)
Net cash and cash equivalents provided by investing activities	32,755	6,791
Cash flows from financing activities:
Payments on finance lease	(58)	(43)
Payments on deferred offering costs	(4,116)
Payments of series B-1 issuance cost	(405)
Proceeds from exercise of warrants for series A redeemable convertible preferred stock	1,125	125
Proceeds from issuance of redeemable convertible preferred stock Series B-1, net of $37 issuance costs paid	40,000	84,963
Proceeds from exercise of stock options	260	487
Net cash and cash equivalents provided by financing activities	192,348	85,532
Net increase in cash, cash equivalents, and restricted cash	150,840	45,556
Cash, cash equivalents, and restricted cash, beginning of period	70,103	24,547
Cash, cash equivalents, and restricted cash, end of period	220,943	70,103
Reconciliation to amounts on the consolidated balance sheet:
Cash and cash equivalents	220,383	69,565
Restricted cash	560	538
Cash, cash equivalents, and restricted cash, end of period	220,943	70,103
Supplemental disclosures of cash flow information:
Interest paid		6
Income taxes paid		1
Supplemental disclosures of noncash financing and investing activities:
Leasehold improvement directly paid by landlord	79	3,990
Liability in connection to the issuance of redeemable convertible preferred stock series B-1	14,560	3,174
Mark to market adjustments for available-for-sale investments	68
Unpaid issuance cost in connection to the issuance of redeemable convertible preferred stock series B-1		405
Equipment acquired through finance lease		259
Vesting of early exercised options	363
Acquisition of right-of-use asset through operating lease obligation		252
PP&E Purchase still in Accounts Payable	82
Change in pension obligation	(142)
Conversion of redeemable convertible preferred stock to common stock in connection with initial public offering	238,522
Change in fair value of derivative liability upon exercise of warrants	757	$ 51
Initial Public Offering
Cash flows from financing activities:
Proceeds from issuance of common stock	139,500
Over-Allotment Option
Cash flows from financing activities:
Proceeds from issuance of common stock	$ 16,042

Consolidated statements of ca_2

Consolidated statements of cash flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Redeemable Convertible Preferred Stock Series B-1
Issuance costs	$ 37	$ 37

Organization

Organization	12 Months Ended
	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	1. Organization Description of business Aligos Therapeutics, Inc. (Aligos-US) was incorporated in the state of Delaware on February 5, 2018 (inception). On September 10, 2018, the Company formed Aligos Belgium BVBA (the Subsidiary or Aligos-Belgium). On March 30, 2020, the Company formed as a wholly owned subsidiary, Aligos Australia Pty LTD (Aligos-Australia), a proprietary limited company, and together with Aligos-US and Aligos-Belgium being the Company or Aligos. Aligos is a clinical-stage biopharmaceutical company developing novel therapeutics to address unmet medical needs in viral and liver diseases, including chronic hepatitis B and coronaviruses and therapeutics for nonalcoholic steatohepatitis (NASH). The Company is devoting substantially all of its efforts to the research and development of its drug candidates. The Company has not generated any product revenue to date. The Company is also subject to a number of risks similar to other companies in the biotechnology industry, including the uncertainty of success of its preclinical studies and clinical trials, regulatory approval of drug candidates, uncertainty of market acceptance of products, competition from substitute products and larger companies, the need to obtain additional financing, compliance with government regulations, protection of proprietary technology, dependence on third-parties, product liability, and dependence on key individuals. Reverse stock split On October 8, 2020, the Company’s board of directors approved a 1-for-9.3197 reverse stock split (the Reverse Stock Split) of the Company’s common stock and redeemable convertible preferred stock to be consummated prior to the effectiveness of the Company’s planned initial public offering (IPO). The par value and authorized shares of the common stock and redeemable convertible preferred stock were not adjusted as a result of the reverse stock split. All issued and outstanding common stock, options to purchase common stock and per share amounts contained in the financial statements have been retroactively adjusted to give effect to the reverse stock split for all periods presented. The Company filed an amended and restated certificate of incorporation in Delaware on October 9, 2020 that automatically effectuated the Reverse Stock Split without any further action required. Initial public offering On October 20, 2020, the Company closed its IPO and issued 10,000,000 shares of its common stock at a public offering price of $15.00 per share for net proceeds of $135.4 million, after deducting underwriting discounts and commissions of $10.5 million and expenses of $4.1 million. In connection with the IPO, all shares of Series A redeemable convertible preferred stock (Series A), Series B-1 redeemable convertible preferred stock (Series B‑1) and Series B-2 redeemable convertible preferred stock (Series B-2) converted into 19,761,870 shares of voting common stock and 3,092,338 shares of non-voting common stock. On November 5, 2020, the underwriters of the IPO partially exercised their overallotment option by purchasing an additional 1,150,000 shares from the Company, resulting in an additional $16.0 million in net proceeds, after deducting underwriting discounts and commissions of $1.2 million. Liquidity and going concern assessment The Company has incurred losses and negative cash flows from operations since its inception. As of December 31, 2020 and 2019, the Company has an accumulated deficit of approximately $174.7 million and $66.2 million, respectively. Management expects to continue to incur additional substantial losses in the foreseeable future as a result of expanded research and development activities. As of December 31, 2020, the Company has unrestricted cash, cash equivalent and short-term investments of approximately $243.5 million, which is available to fund future operations. The Company expects to continue to spend substantial amounts to continue the nonclinical and clinical development of its current and future programs. If the Company is able to gain marketing approval for drug candidates that are being developed, it will require significant additional amounts of cash in order to launch and commercialize such drug candidates. In addition, other unanticipated costs may arise. Because the design and outcome of the Company’s planned and anticipated clinical trials is highly uncertain, the Company cannot reasonably estimate the actual amounts necessary to successfully complete the development and commercialization of any drug candidate the Company may develop. The Company expects to finance its cash needs through a combination of public or private equity offerings, debt financings, collaborations, strategic alliances, licensing arrangements and other marketing or distribution arrangements. In addition, the Company may seek additional capital to take advantage of favorable market conditions or strategic opportunities even if the Company believes it has sufficient funds for its current or future operating plans. Based on the Company’s research and development plans, it is expected that the Company’s existing cash, cash equivalents and investments, will enable the Company to fund its operations for at least 12 months following the date the consolidated financial statements are issued. However, the Company’s operating plan may change as a result of many factors currently unknown, and the Company may need to seek additional funds sooner than planned. Moreover, it is particularly difficult to estimate with certainty the Company’s future expenses given the dynamic nature of its business, the COVID-19 pandemic and the macro-economic environment generally. The Company’s ability to raise additional funds will depend on financial, economic and other factors, many of which are beyond its control. In particular, the COVID-19 pandemic continues to rapidly evolve and has already resulted in a significant disruption of global financial markets. If the disruption persists or deepens, the Company could be unable to access additional capital, which could negatively affect its ability to consummate certain corporate development transactions or other important, beneficial or opportunistic investments. If additional funds are not available to the Company when needed, on terms that are acceptable to the Company, or at all, the Company may be required to: delay, limit, reduce or terminate nonclinical studies, clinical trials or other research and development activities or eliminate one or more of its development programs altogether; or delay, limit, reduce or terminate its efforts to establish manufacturing and sales and marketing capabilities or other activities that may be necessary to commercialize any future approved products, or reduce the Company’s flexibility in developing or maintaining its sales and marketing strategy.

Summary of significant accounti

Summary of significant accounting policies	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of significant accounting policies	2. Summary of significant accounting policies The accompanying consolidated financial statements have been prepared on a basis that assumes the Company will continue as a going concern and contemplates the continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the normal course of business. Basis of presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and include all adjustments necessary for the fair presentation of the Company’s financial position for the periods presented. Any reference in these notes to applicable accounting guidance is meant to refer to the authoritative U.S. GAAP included in the Accounting Standards Codification (ASC), and Accounting Standards Update (ASU) issued by the Financial Accounting Standards Board (FASB). Principles of consolidation The accompanying consolidated financial statements include Aligos-US and its wholly owned subsidiaries Aligos-Belgium and Aligos-Australia. All intercompany balances and transactions have been eliminated. Use of estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP generally requires management to make certain estimates and assumptions that affect the reported amounts in the consolidated financial statements and accompanying notes. The Company regularly evaluates estimates and assumptions related to assets and liabilities, at the dates of the consolidated financial statements and the reported amounts of expenses during the reporting period. Areas where management uses subjective judgments include, but are not limited to, right-of-use assets, lease obligations, impairment of long-lived assets, stock-based compensation, accrued research and development costs, pension liabilities, derivative liabilities and redeemable convertible preferred stock liability in the accompanying consolidated financial statements. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ materially from these estimates under different assumptions or conditions. Foreign currency The Company’s foreign subsidiaries use the U.S. dollar as their functional currency, and they initially measure the foreign currency denominated assets and liabilities at the transaction date. Monetary assets and liabilities are then re-measured at exchange rates in effect at the end of each period, and non-monetary assets and liabilities are converted at historical rates. A re-measurement gain was recognized during the year ended December 31, 2020 of $121,000 and a re-measurement loss was recognized during the year ended December 31, 2019 of Segment information The Company has determined that the Chief Executive Officer is its Chief Operating Decision Maker. The Company’s Chief Executive Officer reviews financial information presented on a consolidated basis for the purposes of assessing the performance and making decisions on how to allocate resources. Accordingly, the Company has determined that it operates in a single reportable segment. No revenue has been generated since inception. The Company has $6.6 million and $1.4 million of fixed assets in Aligos-US and Aligos-Belgium, respectively, as of December 31, 2020 and $7.3 million and $1.2 million of fixed assets in Aligos-US and Aligos‑Belgium, respectively as of December 31, 2019. Cash equivalents The Company considers all highly liquid investments purchased with original maturities of 90 days or less at acquisition to be cash equivalents. Restricted cash As of December 31, 2020 and 2019, the restricted cash balance was $560,000 and $538,000, respectively, and was used to secure the letters of credit in relation to the Company’s operating leases and deposits on rental assets (Note 6). Investments The Company determines the appropriate classification of debt securities at the time of purchase and re-evaluates such designation as of each balance sheet date. Debt securities are classified as held-to-maturity when the Company has the positive intent and ability to hold the securities to maturity, otherwise debt securities are classified as available-for sale. Held-to-maturity securities are carried at amortized cost. Available-for-sale debt securities are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale debt securities are reported as a separate component of stockholders’ deficit. Premiums or discounts from par value are amortized to investment income over the life of the underlying investment. The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in interest and other (expense) income, net within the condensed consolidated statements of operations and comprehensive loss. For both held-to-maturity and available-for-sale investments, the Company periodically reviews each individual security position that has an unrealized loss, or impairment, to determine if that impairment is other-than-temporary. If the Company believes an impairment of a security position is other than temporary, based on available quantitative and qualitative information as of the report date, the loss will be recognized as other income (expense) in the Company’s condensed consolidated statements of operations and a new cost basis in the investment is established. No impairment charges were recorded during the years ended December 31, 2020 and 2019. As of December 31, 2020 and 2019, short-term investments consisted of U.S. Treasury securities with original maturities of less than one year. As of December 31, 2019, long-term investments consisted of U.S. Treasury securities with original maturities of more than one year. Deferred offering costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of the financing, these costs are recorded as a reduction of the proceeds received from the equity financing. If a planned equity financing is abandoned, the deferred offering costs are expensed immediately as a charge to operating expenses in the consolidated statement of operations and comprehensive loss. There were no deferred offering costs on the Company’s consolidated balance sheets at December 31, 2020 and 2019. Concentrations of credit risk and significant suppliers The Company has no significant off-balance sheet risk, such as foreign exchange contracts, option contracts, or other foreign hedging arrangements. Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, restricted cash and investments. Periodically, the Company maintains deposits in accredited financial institutions in excess of federally insured limits. The Company deposits its cash in financial institutions that it believes have high credit quality and has not experienced any losses on such accounts and does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company generally invests its excess capital in money market funds, U.S. treasury bonds and U.S. treasury bills that are subject to minimal credit and market risks. The Company is dependent on various third parties to manufacture compounds for the Company to conduct research and studies for its programs. These programs would be adversely delayed by a significant interruption in the supply of active pharmaceutical ingredients. Leases The Company determines if an arrangement is a lease at the inception of the lease. Operating leases are included in operating lease right-of-use (ROU) assets and operating lease liabilities in the consolidated balance sheet. Finance leases are included in property and equipment and finance lease liabilities in the consolidated balance sheet. ROU assets represent the right to use an underlying asset for the lease term and lease liabilities represent the obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. When the Company’s leases do not provide an implicit rate, an incremental borrowing rate is used based on the information available at the commencement dates in determining the present value of lease payments. The Company uses the implicit rate when readily determinable. The operating lease ROU assets also include any lease payments made and excludes lease incentives when paid by the Company or on the Company’s behalf. The Company’s lease terms may include the period covered by options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for operating leases is recognized on a straight-line basis over the lease term. The Company has lease agreements with lease and non-lease components. The Company elected to not separate lease and non-lease components for all of its building leases. For vehicle leases, lease and non-lease components are accounted for separately. The Company also made an accounting policy election to recognize lease expense for leases with a term of 12 months or less on a straight-line basis over the lease term and not recognize ROU assets or lease liabilities for such leases. Property and equipment Property and equipment is stated at cost less accumulated depreciation, and is depreciated using the straight-line method over the estimated useful life of the asset, which are as follows: Lab equipment 3 years Computer equipment 3 years Furniture and office equipment 3-8 years Vehicles 4 years Leasehold improvements Shorter of the useful life or remaining lease term Expenditures for repairs and maintenance of assets are charged to expense as incurred. Upon retirement or sale, the cost and related accumulated depreciation of assets disposed of are removed from the accounts and any resulting gain or loss is included in loss from operations. Impairment of long-lived assets The Company regularly reviews the carrying amount of its property, equipment and intangible assets to determine whether indicators of impairment may exist which warrant adjustments to carrying values or estimated useful lives. If indications of impairment exist, projected future undiscounted cash flows associated with the asset are compared to the carrying amount to determine whether the asset’s value is recoverable. If the carrying value of the asset exceeds such projected undiscounted cash flows, the asset will be written down to its estimated fair value. No impairment charges were recorded during the years ended December 31, 2020 or 2019. Research and development expenses Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries, stock-based compensation and benefits, facilities costs, depreciation, and third-party license fees. Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. In-process research and development (IPR&D) expense represents the costs to acquire technologies to be used in research and development that have not reached technological feasibility or have no alternative future uses and thus are expensed as incurred. IPR&D expense also includes upfront license fees and milestones paid to collaborators for technologies with no alternative use. Collaborative arrangements The Company enters into collaboration arrangements with pharmaceutical and other partners, under which the Company may grant licenses to its collaboration partners to research and develop potential drug candidates. Consideration under these contracts may include an upfront payment, development, regulatory, sales and other milestone payments. Contractual payments received for research and development activities performed are recognized on a gross basis in revenue from collaboration arrangements. The Company may also perform research and development activities under the collaboration agreements where the Company may be granted licenses from its collaboration partners. Contractual payments to the other party in collaboration agreements and costs incurred by the Company are recognized on a gross basis in research and development expenses. Royalties and license payments are recorded as due. When the Company enters into collaboration arrangements, the Company assesses whether the arrangement fall within the scope of ASC 808, Collaborative Arrangements Revenue from Contracts with Customers During the year ended December 31, 2019, no milestones were met and no royalties were due; therefore, the Company did not pay or expense any milestone or royalties. In the year ended December 31, 2020, a development milestone was met as the first patient dosing occurred and so the Company made a payment of $4.5 million, which is included in research and development in the consolidated statement of operations. The upfront payment received during the year ended December 31, 2020 was recorded on the consolidated balance sheet as deferred revenue from collaborations. Fair value measurements Certain assets and liabilities of the Company are carried at fair value under U.S. GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: Level 1 —Quoted prices in active markets for identical assets or liabilities. Level 2 —Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. Level 3 —Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. Stock-based compensation The Company’s stock-based awards consist of restricted stock awards and stock options. For stock-based awards issued to employees and nonemployees, the Company measures the estimated fair value of the stock-based awards on the date of grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the respective awards. The Company records expense for awards with service-based vesting using the straight-line method. The Company accounts for forfeitures as they occur. The Company classifies stock-based compensation expense in its consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s cash compensation costs are classified. The fair value of each restricted stock award is determined based on the number of shares granted and the value of the Company’s common stock on the date of grant. The fair value of each stock option award is estimated on the date of grant using the Black-Scholes option pricing model. The Black-Scholes option-pricing model requires the use of a number of assumptions including the fair value of the common stock, expected volatility, risk-free interest rate, expected dividends, and expected term of the option. The Company determined the expected stock volatility using a weighted-average of the historical volatility of a group of guideline companies that issued options with substantially similar terms, and expects to continue to do so until such time as the Company has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options has been determined utilizing the simplified method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The Company has not paid, and does not anticipate paying, cash dividends on its common stock; therefore, the expected dividend yield is assumed to be zero. See Note 9 for the assumptions used by the Company in determining the grant date fair value of stock-based awards granted, as well as a summary of the stock-based award activity under the Company’s stock-based compensation plan for years ended December 31, 2020 and 2019. Income taxes Deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established. The Company accounts for uncertain tax positions recognized in the consolidated financial statements by prescribing a more-likely-than-not threshold for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related interest and penalties. Net loss per share 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 during the period, without consideration for potentially dilutive securities. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, redeemable convertible preferred stock, stock options, common stock subject to repurchase related to early exercise of stock options, unvested restricted stock subject to repurchase, warrants and convertible notes are considered to be potentially dilutive securities. The Company applies the two-class method to calculate its basic and diluted net loss per share as the Company has issued shares that meet the definition of participating securities. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common stockholders. The Company’s participating securities contractually entitle the holders of such shares to participate in dividends, but do not contractually require the holders of such shares to participate in losses of the Company. Accordingly, in periods in which the Company reports a net loss, such losses are not allocated to such participating securities. Accordingly, in periods in which the Company reports a net loss, diluted net loss per share is the same as basic net loss per share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive. Benefit plans The Company has established a defined contribution savings plan for its employees in Aligos-US under Section 401(k) of the Internal Revenue Code, and a defined benefits plan for its employees in Aligos-Belgium. The Company uses the standard method for the recognition of the actuarial results as described in ASC 715. This means application of a 10% corridor and amortization over the expected average remaining working lives of the employees. The plan contains benefits to the plan participant on the normal plan retirement date and benefits to the partner after death of the plan participant. This plan is recognized under ASC 715. Recently adopted accounting pronouncements In June 2018, the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting Compensation-Stock Compensation In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808)—Clarifying the Interaction between Topic 808 and Topic 606 In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230) Restricted Cash In March 2017, the FASB issued ASU No. 2017-07, Compensation-Retirement Benefits (ASC Topic 715) In August 2018, the FASB issued ASU No. 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20) In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework— Changes to the Disclosure Requirements for Fair Value Measurement Recently issued accounting standards In June 2016, the FASB issued ASU No. 2016-13. Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments—Credit Losses Codification Improvements to Topic 326, Financial Instruments—Credit Losses Codification Improvements to Topic 326 Financial Instruments—Credit Losses In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes From time to time, new accounting pronouncements are issued by FASB that the Company adopts as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has the option to not “opt out” of the extended transition related to complying with new or revised accounting standards. This means that when a standard is issued or revised and it has different application dates for public and nonpublic companies, the Company has the option to adopt the new or revised standard at the time nonpublic companies adopt the new or revised standard and can do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company.

Property and equipment

Property and equipment	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Property and equipment	3. Property and equipment The components of property and equipment were as follows as of December 31, 2020 and 2019: (in thousands) 2020 2019 Leasehold improvements $ 5,655 $ 5,100 Lab equipment 4,833 3,204 Computer equipment 942 890 Furniture and office equipment 459 425 Vehicles 296 296 Asset under construction 65 110 Total, at cost 12,250 10,025 Accumulated depreciation (4,243 ) (1,508 ) Total, net $ 8,007 $ 8,517 During the years ended December 31, 2020 and December 31, 2019, depreciation expense was $2.7 million and $1.4 million, respectively. Finance leases for vehicles are also included in property and equipment on the consolidated balance sheets (Note 6).

Investments

Investments	12 Months Ended
	Dec. 31, 2020
Debt Securities Available For Sale And Held To Maturity [Abstract]
Investments	4. Investments As of December 31, 2020 and 2019, amortized cost, gross unrealized gains and losses, and estimated fair values of total fixed-maturity securities were as follows: 2019 Gross Gross Amortized Unrealized Unrealized Estimated (in thousands) Cost Gain Loss Fair Value Held-to-maturity securities: U.S. Treasury bonds $ 58,117 $ 31 $ (1 ) $ 58,147 2020 Gross Gross Amortized Unrealized Unrealized Estimated (in thousands) Cost Gain Loss Fair Value Held-to-maturity securities: U.S. Treasury bonds $ 10,002 $ 14 $ — $ 10,016 Available-for-sale securities: U.S. Treasury bonds $ 13,060 $ 68 $ — $ 13,128 $ 23,062 $ 82 $ — $ 23,144 Changes in fair value are related to changes in market interest rates. The Company expects to collect all contractual principal and interest payments. Amortized cost and estimated fair value of fixed-maturity securities at December 31, 2020 by contractual maturity were as follows: 2020 (in thousands) Amortized Cost Estimated Fair Value Amounts maturing in: One year or less $ 23,062 $ 23,144 More than one year — — Total investments $ 23,062 $ 23,144 The Company recorded interest income of $1.2 million and $1.6 million, respectively, during the years ended December 31, 2020 and 2019, as a component of interest and other income (expense), net on the Company’s consolidated statement of operations and comprehensive loss.

Accrued liabilities

Accrued liabilities	12 Months Ended
	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued liabilities	5. Accrued liabilities Accrued liabilities consisted of the following as of December 31: (in thousands) 2020 2019 Accrued compensation $ 7,274 $ 3,211 Accrued payables 8,554 3,113 Liability with early exercised stock options 569 753 Other 167 522 Total $ 16,564 $ 7,599

Leases

Leases	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Leases	6. Leases The Company has operating and finance leases for corporate offices, research and development facilities, and certain vehicles. These leases have remaining lease terms of four to eight and a half years, some of which include options to extend the leases for five to eight years. The Company has determined that it is not reasonably certain to exercise the options under any leases. The lease of research and development facilities includes costs for utilities and common area maintenance which have been included in the calculation of lease payments. Differences between lease payments as measured at lease inception and variations in monthly payments will be recognized as operating expenses in the period in which the obligation is incurred. Leases with an initial term of 12 months or less are not recorded on the balance sheet, and the Company recognizes lease expense for these leases on a straight-line basis over the lease terms. Leases with terms greater than 12 months are included in operating lease ROU assets and operating lease liabilities in the Company’s consolidated balance sheets as of December 31, 2020 and 2019. Lease expense for lease payments is recognized on a straight-line basis over the lease term. Maturities of lease liabilities as of December 31, 2020, were as follows: (in thousands) Operating Lease Finance Lease Year ending December 31: 2021 $ 2,616 $ 80 2022 2,700 79 2023 2,696 42 2024 2,678 1 2025 2,772 — Thereafter 3,642 — 17,104 202 Less: imputed interest (4,291 ) (8 ) Present value of lease liabilities 12,813 194 Less: current portion (2,442 ) (64 ) Lease liabilities net of current portion $ 10,371 $ 130 The components of lease expense were as follows for the years ended December 31, 2020 and 2019: (in thousands) 2020 2019 Operating lease cost $ 1,847 $ 2,228 Finance lease cost: Amortization of right-of-use assets 60 46 Interest on lease liabilities 9 6 Total finance lease cost $ 69 $ 52 Short-term lease cost $ 15 $ 11 The Company made payments of $2.5 million and $1.2 million during the years ended December 31, 2020 and 2019, respectively, which are included as cash flow from operations on the consolidated statements of cash flows. As of December 31, 2020 and 2019, $296,000 and $296,000 of finance lease ROU assets, respectively, were presented as part of property and equipment on the consolidated balance sheet with accumulated amortization of $107,000 and $47,000, respectively. Additional information related to the Company’s leases was as follows as of December 31: 2020 2019 Operating Lease: Weighted-average remaining lease term (years) 5.97 7.10 Weighted-average discount rate 9.35 % 9.34 % Finance Lease: Weighted-average remaining lease term (years) 2.68 3.66 Weighted-average discount rate 3.15 % 3.18 %

Derivative liabilities and rede

Derivative liabilities and redeemable convertible preferred stock liability	12 Months Ended
	Dec. 31, 2020
Derivative Liabilities And Redeemable Convertible Preferred Stock Liability [Abstract]
Derivative liabilities and convertible preferred stock liability	7. Derivative liabilities and redeemable convertible preferred stock liability Warrants In connection with the issuance of the Notes, Lenders were issued Warrants to purchase 134,112 shares of the Company’s capital stock. The Warrants have a coverage percentage of 25% of the principal amount of the Notes and have a ten-year expiration date from the applicable closing date of April 20, 2018 or June 6, 2018. The underlying shares issuable upon the exercise of the Warrants were eligible to be converted into the next round of equity financing. The Warrants became exercisable into shares of Series A for an exercise price of $9.32 per share. The Company recorded the Warrants initially at fair value (Note 10) as derivative liabilities on the consolidated balance sheet with the remaining value being allocated to the Notes as a debt discount. The fair value of the Warrants upon issuance on April 20, 2018 and June 6, 2018, was $0.7 million and $238,000, respectively. The fair value of the Warrants was $0 and $461,000 as of December 31, 2020 and 2019, respectively. In December 2019, Warrants were exercised into 13,411 shares of Series A. As a result, there were Warrants to purchase 120,701 shares of Series A outstanding as of December 31, 2019. Following completion of an IPO or change of control, any then outstanding warrants will automatically be exercised, on net share basis, for the issuance of shares of Common Stock and, upon that exercise, such warrants will no longer be outstanding. Redeemable convertible preferred stock liability In connection with the issuance of Series B-1 Redeemable Convertible Preferred Stock (the Series B-1) (Note 8), the Series B-1 preferred stockholders committed to purchase and the Company committed to sell 3,569,630 shares of Series B-2 Redeemable Convertible Preferred Stock (the Series B-2) at a price of $11.20563 per share in a subsequent closing, contingent upon the achievement of certain developmental milestones or a receipt of a waiver of achievement of the milestones. The Redeemable Convertible Preferred Stock Liability is considered a freestanding instrument that qualifies as a liability under ASC Topic 480, Distinguishing Liabilities from Equity As of December 31, 2020, all Series B-2 shares were issued and then, as a result of the IPO, converted to shares of common stock. The Company recorded a change in fair value of the liability of $11.4 million for the year ended December 31, 2020 included in other expense, net. The convertible preferred stock liability was retired as of December 31, 2020. As of December 31, 2019, none of the Series B-2 shares were issued and the fair value of the liability related to this freestanding instrument remained unchanged.

Capital stock

Capital stock	12 Months Ended
	Dec. 31, 2020
Equity [Abstract]
Capital stock	8. Capital stock Common stock On February 5, 2018, the date of incorporation, the Company was authorized to issue 20,000,000 shares of common stock with a par value of $0.0001 per share (the Common Stock). On March 19, 2018, the Company granted two founders the right to purchase 1,508,900 shares of the Company’s Common Stock at a purchase price of $0.001 per share upon the terms and subject to the conditions set forth in a restricted stock purchase agreement. The shares were purchased for $2 on the grant date and the shares vested immediately upon grant. On March 19, 2018, the Company granted two founders and one employee the right to purchase 425,585 shares of the Company’s Common Stock at a purchase price of $0.001 per share upon the terms and subject to the conditions set forth in a restricted stock purchase agreement. The shares were purchased for a de-minimis amount on the grant date and the shares vest monthly over a three-year period after a one-year cliff. If the purchasers no longer provide services to the Company, any portion of the shares that have not vested pursuant to the vesting schedule shall, on the date that is 61 days following such termination of service, automatically be forfeited by purchaser without any additional consideration therefore and without any further action by the Company and such shares shall immediately be canceled by the Company and shall no longer be outstanding. On July 23, 2018, the certificate of incorporation was amended to increase the number of shares authorized for issuance to 25,000,000 shares of Common Stock. On that same date, the Company issued for purchase by employees and founders an additional 77,379 shares for a de-minimis amount subject to the same terms and conditions as the shares issued on March 19, 2018. The Common Stock issuances with vesting conditions were issued outside of the equity incentive plan and are described in more detail in Note 9—Stock-based compensation. On August 15, 2018, the certificate of incorporation was amended to increase the total shares of Common Stock authorized for issuance to 149,000,000 and additionally 102,500,000 shares of preferred stock with a par value of $0.0001 per share. Effective immediately on filing date, the Company converted all shares of Common Stock into 0.90144231 shares of Common Stock (the 2018 Reverse Stock Split). All share and data shown in the accompanying consolidated financial statements and related notes have been retroactively revised to reflect the 2018 Reverse Stock Split. Shares of Common Stock underlying outstanding stock options and other equity instruments were proportionately reduced and the respective exercise prices, if applicable, were proportionately increased in accordance with the terms of the agreements governing such securities. On December 23, 2019, the certificate of incorporation was amended to increase the total shares of Common Stock authorized for issuance to 278,000,000 and the total shares of preferred stock authorized for issuance to 212,994,964 with a par value of $0.0001 per share. The total shares of preferred stock authorized comprised 101,962,864 shares of Series A, 77,764,055 shares of Series B-1, and 33,268,045 shares of Series B-2. On October 20, 2020, the certificate of incorporation was amended to increase the total shares of Common Stock authorized for issuance to 320,000,000 and decrease the total shares of preferred stock authorized for issuance to 10,000,000 with a par value of $0.0001 per share. 300,000,000 shares of the Common Stock were designated as “Voting Common Stock” and 20,000,000 shares of the Common Stock were designated as “Non-Voting Common Stock”. The holders of shares of Common Stock are entitled to one vote for each share of Common Stock at all meetings of stockholders. Redeemable convertible preferred stock On August 16, 2018, the Company entered into the Series A Preferred Stock Purchase Agreement for the purchase and sale of Series A preferred stock for $9.32 per share. The Company received $75.0 million in cash proceeds from the initial purchasers. On September 19, 2018, the Company received an additional $20.0 million in cash proceeds from subsequent purchasers. Additionally, on the initial closing date, $5.6 million in convertible notes plus accrued interest converted into shares of Series A and the notes were subsequently cancelled. The Warrants associated with the convertible notes became exercisable into Series A. Each share of Series A is convertible into Common Stock on a one-for-one basis. In connection with the issuance of Series A, the Company incurred $194,000 in issuance costs which have offset amounts reported as temporary equity as of December 31, 2019. As of December 31, 2020, in connection with the Company’s IPO, all shares of Series A converted into Common Stock. On December 23, 2019, the Company entered into the Series B-1 and Series B-2 Preferred Stock Purchase Agreement, pursuant to which the investors committed to invest an aggregate amount of up to $125.0 million for the issuance and sale of shares of Series B-1 and Series B-2 (collectively, the Series B), at a price of $10.18690 and $11.20563 per share, respectively. The Company issued 8,344,034 shares of Series B-1 for cash proceeds of $85.0 million at the initial closing on December 23, 2019. The investors also committed to purchase and the Company committed to sell 3,569,630 shares of Series B-2 in a subsequent closing (the Second Closing), contingent upon achievement by the Company of certain development milestones or a receipt of a waiver of achievement of the milestones. No shares of Series B-2 were issued as of December 31, 2019. In connection with the issuance of Series B-1, the Company incurred $442,000 in issuance costs which have offset amounts reported as temporary equity as of December 31, 2019. Prior to the IPO, the Company issued 3,569,630 shares of Series B-2, which upon the closing of the IPO converted into common stock. In connection with the Company’s IPO, all shares of Series B-1 converted into common stock. As of December 31, 2020, there was 10,000,000 shares of preferred stock authorized and no preferred stock issued.

Stock-based compensation

Stock-based compensation	12 Months Ended
	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-based compensation	9. Stock-based compensation 2018 Equity incentive plan The Company’s 2018 Equity Incentive Plan (the 2018 Plan) allows the Company to issue restricted stock awards and restricted stock units, and to grant incentive stock options or non-qualified stock options. Incentive stock options may be granted only to the Company’s employees including officers and members of the Board who are also employees. Restricted stock awards, restricted stock units and non-qualified stock options may be granted to employees, members of the Board, outside advisors, and consultants of the Company (the Participants). The Company is authorized to issue awards for 4,913,665 shares of Common Stock under the 2018 Plan. The Company has granted awards of common stock in the form of 4,279,693 shares as of December 31, 2020 with none remaining available for future grant. 2020 Incentive award plan The Company adopted the 2020 Incentive Award Plan (the 2020 Plan) effective October 15, 2020. The 2020 Plan provides for a variety of stock-based compensation awards, including stock options, stock appreciation rights, or SARs, restricted stock awards, restricted stock unit awards, performance bonus awards, performance stock unit awards, dividend equivalents, or other stock or cash based awards. The Company has granted 3,374,466 shares subject to awards as of December 31, 2020 with 1,068,965 remaining available for future grant Following the effectiveness of the 2020 Plan, the Company will not make any further grants under the 2018 Plan. However, the 2018 Plan will continue to govern the terms and conditions of the outstanding awards granted under this plan. Shares of common stock subject to awards granted under the 2018 Plan that are forfeited or lapse unexercised and which following the effective date of the 2020 Plan are not issued under the 2018 Plan will be available for issuance under the 2020 Plan. 2020 Employee stock purchase plan The Company adopted the 2020 Employee Stock Purchase Plan (the 2020 ESPP) effective on October 15, 2020. The 2020 ESPP will enable eligible employees of the Company to purchase shares of common stock at a discount to fair market value. The Company has initially reserved for issuance 368,901 shares of common stock pursuant to the 2020 ESPP. As of December 31, 2020, no grants of awards under this plan have been made. Stock options The exercise price for incentive stock options is at least 100% of the fair market value on the date of grant for stockholders owning less than 10% of the voting power of all classes of stock, or at least 110% of the fair market value for stockholders owning more than 10% of the voting power of all classes of stock. Options generally expire in 10 years and vest over periods determined by the Board, generally 48 months. Certain stock options referred to as “early exercise stock options” permit the holders to exercise the option in whole or in part prior to the full vesting of the option in exchange for unvested shares of Restricted Stock with respect to any unvested portion of the option so exercised. During the years ended December 31, 2020 and December 31, 2019, the Company’s stock option compensation expense was approximately $2.6 million and $261,000, respectively, and there was no recognized tax benefit in either year. As of December 31, 2020, unamortized expense balance was $38.8 million, to be amortized over a weighted-average period of 3.43 years. The assumptions that the Company used to determine the grant-date fair value of stock options granted to Participants were as follows, presented on a weighted-average basis: 2020 2019 Expected term (in years) 5.79 6.06 Risk-free interest rate 0.93% 1.94% Dividend yield — — Volatility 77.14% 60.24% Stock option activity during the year ended December 31, 2020 and 2019 was as follows: Number of Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding as of December 31, 2018 1,062,457 $ 1.30 9.88 $ — Granted 178,863 $ 1.30 Exercised (891,229 ) $ 1.30 37 Forfeited (3,219 ) $ 1.30 Outstanding as of December 31, 2019 346,872 $ 1.30 9.01 $ 744 Granted 5,382,362 $ 11.42 Exercised (188,990 ) $ 2.33 810 Forfeited (52,096 ) $ 1.76 Outstanding as of December 31, 2020 5,488,148 $ 11.19 9.57 $ 90,335 Options vested and expected to vest as of December 31, 2020 5,427,891 $ 11.28 9.58 $ 88,881 Options vested and exercisable as of December 31, 2020 464,567 $ 3.20 8.95 $ 11,360 Options vested and expected to vest as of December 31, 2019 884,623 $ 1.30 9.01 $ 1,896 Options vested and exercisable as of December 31, 2019 31,330 $ 1.30 8.88 $ 67 The weighted-average grant date fair value of stock options granted was $7.50 per share during the year ended December 31, 2020. The weighted-average grant date fair value of stock options granted was $0.08 per share during the year ended December 31, 2019. During the years ended December 31, 2020 and December 31, 2019, the Company issued 371,939 and 537,781 and shares of Common Stock, respectively, upon exercise of unvested stock options or purchases for unvested restricted stock awards. As of December 31, 2020 and 2019, there were 396,522 and 577,124 shares of Common Stock, respectively, held by employees subject to repurchase at an aggregate price of $0.6 million and $0.7 million, respectively. A corresponding liability was recorded and included in accrued expenses on the consolidated balance sheet as of December 31, 2020 and 2019. Restricted stock awards The Company may grant restricted stock purchase awards to the Participants to purchase restricted stock under the Company’s Plan, which are subject to vesting conditions. The purchase prices of the restricted stock are determined by the Board. The Company has a right to repurchase the shares if the Participant’s service period is not fulfilled or upon termination of service at the original per share issuance price. The right of repurchase lapses over a service period which is typically four years with 25% vesting on the first anniversary of the vesting commencement date and 1/48 each month thereafter. Before the adoption of the Company’s Plan, the Company granted 502,964 restricted stock awards to employees and founders. These restricted stock awards have similar characteristics to the restricted stock awards granted under the Company’s Plan, other than the right of repurchase, which typically lapses over three years with 33% vesting on the first anniversary of the vesting commencement date and 1/36 each month thereafter. During the years ended December 31, 2020 and December 31, 2019, the Company recorded a total stock-based compensation expense of $361,000 and $492,000, respectively, related to the restricted stock awards. As of December 31, 2020, unrecognized stock-based compensation costs related to outstanding unvested restricted stock awards that are expected to vest were approximately $526,000, expected to be recognized over a weighted-average period of 1.14 years. The following table summarizes the Company’s restricted common stock activity for years ended December 31, 2020 and 2019: Number of Awards Weighted- Average Grant Date Fair Value Aggregate Fair Value Issued and unvested as of December 31, 2018 1,521,387 $ 0.94 1,430 Restricted stock awards granted — $ — — Restricted stock awards vested (694,200 ) $ 0.86 (596 ) Issued and unvested as of December 31, 2019 827,187 $ 1.01 $ 834 Restricted stock awards granted — — Restricted stock awards vested (418,776 ) $ 0.86 (361 ) Issued and unvested as of December 31, 2020 408,411 $ 1.16 $ 473 Stock-based compensation expense was allocated as follows for the years ended December 31, 2020 and December 31, 2019: (in thousands) 2020 2019 Research and development $ 1,041 $ 462 General and administrative 1,934 290 Total $ 2,975 $ 752

Fair value

Fair value	12 Months Ended
	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair value	10. Fair value The following tables present the fair value of the Company’s financial instruments that are measured or disclosed at fair value on a recurring basis: Fair Value Measurements as of December 31, 2020 (in thousands) Level 1 Level 2 Level 3 Assets: Cash and cash equivalents $ 220,383 $ — $ — U.S. Treasury bonds 23,144 — — $ 243,527 $ — $ — Fair Value Measurements as of December 31, 2019 (in thousands) Level 1 Level 2 Level 3 Assets: Cash and cash equivalents $ 69,565 $ — $ — U.S. Treasury bonds 58,147 — — Liabilities: Warrants — — (461 ) Convertible Preferred Stock Liability — — (3,174 ) $ 127,712 $ — $ (3,635 ) The level 3 liabilities in the table above are composed of the fair value of Warrants and Conversion Features issued in connection with the Notes, which were subsequently converted into shares of Series A. The fair values of the Warrants and Conversion Features were determined based on significant inputs not observable in the market, which represents a Level 3 measurement within the fair value hierarchy. In order to determine the fair value of the Warrants, the Company utilized a probability-weighted multi-scenario Black-Scholes option-pricing model to determine the fair value of the Warrants by accounting for the probability of multiple possible outcomes, including deemed liquidation events, as best estimated by management. Estimates and assumptions impacting the fair value measurement including the fair value of the underlying shares of Series A, the remaining contractual or expected term of the Warrants, risk-free interest rate, expected dividend yield and expected volatility of the price of the underlying preferred stock on an as converted basis. The Company considered the probability of a deemed liquidation event in determining the remaining expected term of the Warrants, which was used as an input to the probability-weighted multi-scenario Black-Scholes option-pricing model adopted in 2019. The Company lacked company-specific historical and implied volatility information of its stock since there was no market prior to the IPO. Therefore, it estimated its expected stock volatility based on the historical volatility of publicly traded guideline companies for a term equal to the remaining contractual or expected term of the Warrants. The risk-free interest rate was determined by reference to the U.S. Treasury yield curve for time periods approximately equal to the remaining contractual or expected term of the Warrants. The Company estimated no expected dividend yield based on the fact that the Company has never paid or declared dividends and does not intend to do so in the foreseeable future. The Warrants were converted into shares of Series A stock immediately prior to the IPO and therefore they were retired as of December 31, 2020. The Warrants were measured at fair value under the following assumption as of December 31, 2019: 2020 2019 Exercise price $ 9.32 $ 9.32 Term (in years) 0.32 2.00 - 3.00 Risk-free interest rate 0.10 % 1.63 % Dividend yield — — Volatility 120.00 % 75.00 % The fair value of the bifurcated conversion feature was immaterial at inception and is included in the initial fair value of the derivative liabilities. As of December 31, 2020, and 2019, the fair value of the bifurcated conversion feature was $0 as the Notes are converted into shares of Series A preferred stock in August 2018. The following table sets forth a summary of changes in fair value of the Company’s derivative liability for which fair value was determined by Level 3 inputs: Warrants Redeemable Convertible Preferred Stock Liability Balance as of December 31, 2018 $ 861 $ — Exercise of warrants (52 ) — Change in fair value (348 ) 3,174 Balance as of December 31, 2019 $ 461 $ 3,174 Exercise of warrants (137 ) — Change in fair value 296 11,386 Retirement of liability (620 ) (14,560 ) Balance as of December 31, 2020 $ — $ — Immediately prior to the IPO, the Redeemable Convertible Preferred Stock Liability was converted in shares of Series B-2 Preferred Stock, which then converted into shares of common stock. As of December 31, 2020, the liability was retired. As of December 31, 2019, in order to determine the fair value of the Redeemable Convertible Preferred Stock Liability, the Company used a probability weighted multi-scenario Black Scholes hybrid valuation method that accounts for the probability of achieving milestones as estimated by the management. The Redeemable Convertible Preferred Stock Liability has a fair value of $3.2 million at inception, which remained unchanged as of December 31, 2019. The Redeemable Convertible Preferred Stock Liability was measured at fair value under the following assumptions through redemption on October 6, 2020 and as of December 31, 2019: 2020 2019 Exercise price $ 11.21 $ 11.21 Term (in years) 0.02-0.75 1.27 Risk-free interest rate 0.08%-0.11% 1.55% Dividend yield — — Volatility —% 60.00% The significant unobservable inputs used in the fair value measurement of the Redeemable Convertible Preferred Stock Liability include the probability of milestone achievement and/or milestone achievement waiver, the Series B-2 current or future value estimate under each scenario, the term, and the equity volatility, which is a statistical measure of the dispersion of returns for a given security. Significant increases (decreases) in the milestone achievement and/or milestone waiver would result in a significantly higher (lower) fair value measurement. Significant decreases (increases) in assumed current or future Series B-2 value would result in a significantly lower (higher) fair value measurement. Significant increases (decreases) in the term would result in a significantly higher (lower) fair value measurement. Significant increases (decreases) in the volatility would result in significantly higher (lower) fair value measurements.

License agreements and collabor

License agreements and collaborations	12 Months Ended
	Dec. 31, 2020
License And Collaboration Agreements [Abstract]
License agreements and collaborations	11. License agreements and collaborations Agreement with Emory University (Emory) In June 2018, the Company entered into a license agreement with Emory (the Emory License Agreement), pursuant to which Emory granted the Company a worldwide, sublicenseable license under certain of its intellectual property rights to make, have made, develop, use, offer to sell, sell, import and export products containing certain compounds relating to Emory’s hepatitis B virus capsid assembly modulator technology, for all therapeutic and prophylactic uses. Such license is initially exclusive with respect to specified licensed patents owned by Emory and non-exclusive with respect to certain of Emory’s specified know-how. Beginning in June 2022, the license to such patents will become non-exclusive with respect to all fields except for the treatment and prevention of HBV; however, the Company may select up to six compounds which will maintain exclusivity with respect to all therapeutic and prophylactic uses. With respect to all other compounds that are enabled by the licensed patents, those which are jointly invented by the Company and Emory or inventors in the Schinazi laboratory, or which are disclosed in a specified licensed patent, are licensed to the Company exclusively including as to Emory; whereas all other such compounds are licensed to the Company non-exclusively. Under the terms of the Emory License Agreement, the Company is obligated to use commercially reasonable efforts to bring licensed products to market in accordance with a mutually agreed upon development plan. Unless terminated earlier by either party in accordance with the provisions thereof, the Emory License Agreement shall continue until the expiration of the last–to-expire of the patents licensed to the Company thereunder. As consideration for the Emory License Agreement, the Company paid an upfront license fee of $290,000 and issued the Emory Convertible Note of $600,000. As discussed in Note 8, upon issuance of the Series A in August 2018, the Emory Convertible Note and unpaid accrued interest was cancelled and converted into shares of Series A at a conversion price of $9.32 per share. In June 2020, the Company amended the license agreement with Emory. Pursuant to the amended license agreement, Emory granted the Company additional patent rights to certain compounds targeting the treatment or prevention of HBV. As consideration for the additional rights, the Company made a one-time, non-refundable payment to Emory in the amount of $150,000, with an additional obligation to pay up to a maximum of $35,000. On the same date, the Company entered into a collaboration agreement with Emory, with the initial research plan pertaining to the synthesis and evaluation of the compounds licensed through the additional patent rights granted in the amended license agreement. The research plan terminates one year from the effective date, with the Company having an option to extend for a second year. In connection with the research plan, the Company will provide Emory funding up to $270,000 per year. The Company has agreed to pay Emory up to an aggregate of $125.0 million upon the achievement of specified development, regulatory, and commercial milestones, and all ongoing patent costs. During the year ended December 31, 2019, the Company had no expenses related to milestone payments. During the year ended December 31, 2020, the Company made a payment of $4.5 million in relation to the first patient dosing in a clinical trial which was the first development milestone per the contract. The Company also agreed to pay Emory tiered single-digit royalties on worldwide annual net sales of licensed products, on a quarterly basis and calculated on a product-by-product basis. With respect to licensed products containing any of a specified subset of the licensed compounds, such royalties range from a mid-single digit to a high-single digit percentage rate. With respect to licensed products which do not contain such compounds, the royalties span a range of percentage rates within the mid-single digits if a Phase 1 clinical trial is initiated for the product within three years of the effective date of the Emory License Agreement, and range from a low-single digit to a mid-single digit rate if a Phase 1 clinical trial is initiated more than three years after the effective date. During the years ended December 31, 2020 and December 31, 2019, the Company made no payments associated with royalties. Agreement with Luxna Biotech Co., Ltd. (Luxna) On December 19, 2018, the Company entered into a license agreement with Luxna, pursuant to which Luxna granted the Company an exclusive, worldwide, sublicenseable license under certain of Luxna’s intellectual property rights to research, develop, make, have made, and commercialize for all therapeutic and prophylactic uses, (i) products containing oligonucleotides targeting the hepatitis B virus genome, (ii) products containing certain oligonucleotides targeting up to three genes which contribute to NASH, which the Company may select at any time during the first eight years of the term, to the extent not licensed to a third party, and (iii) products containing oligonucleotides targeting up to three genes which contribute to hepatocellular carcinoma, which the Company may select at any time during the first three years of the term. As consideration for this agreement, the Company paid an upfront license fee of $600,000, which was recorded as research and development expense during the period from inception through December 31, 2018 and the year ended December 31, 2019. In April 2020, the Company amended the license agreement with Luxna. Pursuant to the amended license agreement, Luxna granted the Company an exclusive, worldwide license under the licensed patents to research, develop, make, have made and commercialize products containing oligonucleotides targeting three families of viruses: orthomyxoviridae, paramyxoviridae, and coronaviridae (a family which includes SARS-CoV-2). As consideration for the amended license agreement, the Company paid Luxna a one-time non-refundable fee of $200,000. The Company is obligated to make payments to Luxna, in aggregate, totaling up to but no more than $55.5 million upon the achievement of specified development, regulatory, and commercial milestones. During the years ended December 31, 2020 and December 31, 2019, the Company recognized no expenses related to milestone payments. The Company is also required to pay Luxna a low-single digit royalty percentage on net sale of applicable products, if any. During the years ended December 31, 2020 and December 31, 2019, the Company made no payments associated with royalties. Agreement with Katholieke Universiteit Leuven (KU Leuven) On June 25, 2020, the Company entered into a Research, Licensing and Commercialization Agreement (KU Leuven Agreement) with KU Leuven, under which the Company is collaborating with KU Leuven’s Rega Institute for Medical Research, as well as its Centre for Drug Design and Discovery, to research and develop potential protease inhibitors for the treatment, diagnosis or prevention of coronaviruses, including of SARS-CoV-2. Unless terminated earlier by either party in accordance with provisions in the agreement, the collaboration period will terminate at the earlier of completion of all collaboration activities or 2.5 years. In connection with the KU Leuven Agreement, KU Leuven and the Company granted each other exclusive cross-licenses to use certain know-how and existing patents of the other party as well as certain joint know-how and joint patents to carry out research and development collaboration activities during the collaboration period. KU Leuven granted to the Company an exclusive (including as to KU Leuven), worldwide license under certain of KU Leuven’s know-how and existing patents, and certain joint patents and joint know-how, to manufacture and commercialize the licensed products for the treatment, diagnosis or detection of viral infections in humans. KU Leuven reserved the right to use all KU Leuven knowhow, existing KU Leuven patents, joint patents and joint know-how for academic and non-commercial research and teaching purposes. As consideration for this license, the Company is obligated to make payments to KU Leuven, in aggregate, totaling up to but no more than $30.0 million upon the achievement of certain commercial sales milestones. For each licensed product developed through KU Leuven and the Company’s collaborative effort, the Company is obligated to make payments to KU Leuven, in aggregate, totaling up to $32.0 million upon the achievement of certain development and regulatory milestones. The Company is also required to pay KU Leuven a low-to-mid-single digit royalty percentage, subject to certain adjustments, on net sales of applicable products, if any. Unless terminated earlier by either party, the agreement shall continue until the expiration of the last to expire royalty term, which is the later of the expiration or termination of the last valid patent claim covering the manufacture, use, sale or importation of the licensed product in a particular country or 10 years after the first commercial sale of a licensed product. During the years ended December 31, 2020 and December 31, 2019, the Company recognized no expenses related to milestone payments. Agreement with Merck In December 2020, the Company and Merck & Co. entered into an exclusive License and Research Collaboration Agreement under which Merck and the Company agreed to apply the Company’s oligonucleotide platform technology to discover, research, optimize and develop oligonucleotides directed against a NASH target and up to one additional liver-targeted cardiometabolic and/or fibrosis target. Under the terms of the agreement, the Company received an upfront payment from Merck and may receive an additional upfront payment after finalization of a research plan for such additional target. With respect to each collaboration target, the Company will be eligible for up to $458.0 million in development and commercialization milestones as well as tiered royalties on net sales. The Company will be primarily responsible for designing, preparing and evaluating the oligonucleotide molecules and delivering optimized lead molecules, and Merck will be responsible for subsequent research, clinical development and commercialization efforts. The Company determined that the Merck agreement falls within the scope of ASC 808 and we analogized to ASC 606 for the accounting of payments such as upfront payments and other milestones. During the year ending December 31, 2020 the Company recognized no revenue from collaborative arrangements related to milestone payments. The upfront payment received during 2020 was recorded on the consolidated balance sheet as Deferred Revenue from Collaborations.

Income taxes

Income taxes	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Income taxes	12. Income taxes The components of the current provision for income taxes were as follows for the years ended December 31, 2020 and 2019: (in thousands) 2020 2019 Current: State $ 1 $ 1 Federal - $ - Foreign 160 $ 85 Total current provision for income taxes $ 161 $ 86 Deferred: State $ — $ — Federal — — Foreign — — Total deferred provision for income taxes $ — $ — The Company did not have any deferred provision for income taxes for the years ended December 31, 2020 and 2019. A reconciliation of the expected income tax (benefit) computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows for the years ended December 31, 2020 and 2019: 2020 2019 Income tax computed at federal statutory rate 21.00 % 21.00 % State taxes, net of federal benefit 6.90 % 8.18 % R&D credit carryovers 1.40 % 1.87 % Change in valuation allowance (27.24 )% (29.71 )% Permanent differences (0.17 )% (1.32 )% Change in fair value of derivatives (2.25 )% — Other 0.21 % (0.18 )% Effective income tax rate (0.15 )% (0.16 )% The components of the deferred tax assets and liabilities were as follows at December 31: (in thousands) 2020 2019 Deferred tax assets: Federal net operating loss carryforward $ 31,233 $ 12,106 State net operating loss carryforward 10,664 4,227 Foreign net operating loss carryforward 33 — Operating lease liabilities 4,453 3,776 Tax credits 4,639 1,865 Other accruals and reserves 1,558 675 Stock-based compensation 209 — Other 10 7 52,799 22,656 Valuation allowance (49,133 ) (19,362 ) Net deferred tax assets $ 3,666 $ 3,294 Deferred tax liabilities: Right of use assets $ (2,857 ) $ (2,067 ) Stock-based compensation — (115 ) Property and equipment (809 ) (1,112 ) Total deferred tax liabilities $ (3,666 ) $ (3,294 ) Total deferred income taxes $ — $ — Management believes that, based on a number of factors, including the Company’s historical operating performance and accumulated deficit, it is more likely than not that the deferred tax assets will not be utilized, such that full valuation allowance has been recorded against As of December 31, 2020, the Company had $148.7 million of federal and $152.8 million of state net operating loss (NOL) carryforwards available to offset future taxable income. The Company’s federal NOL carryforwards can be carried forward indefinitely while state NOL carryforwards, if not utilized, will begin expiring in 2038. As of December 31, 2020, the Company had research and development credit carryforwards of $4.1 million and $2.1 million available to reduce future taxable income, if any, for federal and state income tax purposes, respectively. If not utilized, the federal credit carryforwards will begin expiring in 2038. The California credit carryforwards have no expiration. Under Sections 382 and 383 of the Code, and corresponding provisions of state law, if a corporation undergoes an “ownership change” (generally defined as a greater than 50 percentage point change (by value) in its equity ownership over a rolling three-year period), the Company’s ability to use its pre-change NOL carryforwards and other pre-change tax attributes to offset its post-change income may be limited. We performed an IRC Section 382 analysis in 2021 and determined there was an ownership change that resulted in Section 382 limitations. The ownership change limited our ability to utilize net operating losses against future taxable income but will not result in the expiration of any NOLs. The Company adopted the provisions of FASB Accounting Standards Codification (ASC 740-10), Accounting for Uncertainty in Income Taxes (in thousands) 2020 2019 Balance, beginning of the period $ 637 $ 79 Increase related to prior year positions 131 — Increase related to current year positions 768 558 Balance, ending of the period $ 1,536 $ 637 The Company files income tax returns in the United States, California and Massachusetts, and in foreign jurisdictions. The Company is not currently under examination by income tax authorities in federal, state or other jurisdictions. All tax returns will remain open for examination by the federal and state authorities for three and four years, respectively, from the date of utilization of any NOLs or credits. In January 2018, the FASB released guidance on the accounting for tax on the global intangible low-taxed income (GILTI) provisions of the Tax Reform Act. The GILTI provisions impose a tax on foreign income in excess of a deemed return on tangible assets of foreign corporations. The guidance allows companies to make an accounting policy election to either (i) account for GILTI as a component of tax expense in the period in which they are subject to the rules (the period cost method), or (ii) account for GILTI in the Company’s measurement of deferred taxes (the deferred method). After completing the analysis of the GILTI provisions, the Company elected to account for GILTI using the period cost method. On March 27, 2020, the “Coronavirus Aid, Relief and Economic Security (CARES) Act” (the “Act”) was signed into law. The Act includes provisions relating to refundable payroll tax credits, deferment of the employer portion of certain payroll taxes, net operating loss carryback periods, alternative minimum tax credit refunds, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. The Company analyzed the provisions of the Act and determined there was no significant impact to its income taxes for the year ended December 31, 2020. On June 29, 2020, the California Governor signed Assembly Bill 85 (“A.B. 85”), which now becomes California law. A.B. 85, which includes several tax measures, provides for a three-year suspension of the use of net operating losses for medium and large businesses and a three-year cap on the use of business incentive tax credits to offset no more than $5 million of tax per year. Generally, A.B. 85 suspends the use of net operating losses for taxable years 2020, 2021, and 2022 for taxpayers with taxable income of $1 million or more.” Since the Company is not expected to generate California source taxable income of more than $1 million, no material impact is anticipated at this time. On December 27, 2020, the “Consolidated Appropriations Act, 2021” (the “CAA”) was signed into law. The CAA includes provisions meant to clarify and modify certain items put forth in CARES Act, while providing aid to businesses affected by the pandemic. The CAA allows deductions for expenses paid for by Paycheck Protection Program (“PPP”) and Economic Injury Disaster Loan (“EIDL”) Program, clarifies forgiveness of EIDL advances, and other business provisions. The Company analyzed the provisions of the CAA and determined there was no significant impact to its 2020 tax provision.

Commitments and contingencies

Commitments and contingencies	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and contingencies	13. Commitments and contingencies From time to time, the Company may have certain contingent liabilities, including legal matters that arise in the ordinary course of its business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated. The Company had no contingent liabilities requiring accrual as of December 31, 2020 and 2019.

Benefit plans

Benefit plans	12 Months Ended
	Dec. 31, 2020
Compensation And Retirement Disclosure [Abstract]
Benefit plans	14. Benefit plans Defined contribution plans The Company established a defined contribution savings plan under Section 401(k) of the Internal Revenue Code. This plan covers substantially all employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. The Company made matching contributions of $432,000 and $274,000 to the plan during the years ended December 31, 2020 and 2019, respectively. Defined benefit plans—regular pension plan ASC Topic 715, Compensation—Retirement Benefits Aligos-Belgium offers its employees a regular pension plan in the form of a defined contribution plan (the Regular Pension Plan), which contains a 1.75% legally required minimum rate of return for the participants. The Regular Pension Plan does not meet all the requirements that are needed for recognition of the plans as a defined contribution plan. The Company therefore recognizes the Regular Pension Plan as a defined benefit plan. Net periodic benefit costs and other amounts recognized in other comprehensive loss for the Regular Pension Plan include the following components for the years ended December 31, 2020 and December 31, 2019: (in thousands) 2020 2019 Service cost $ 186 $ 94 Expected return on plan assets (4 ) (2 ) Interest costs 5 6 Amortization of actuarial gains/(losses) 2 - Other costs 46 29 Prior service costs 33 58 268 185 Net actuarial loss (gain) in plan asset and projected benefit obligation recognized in other comprehensive loss 82 86 Total recognized $ 350 $ 271 The net periodic benefit costs, excluding service costs, are included in interest and other income (expense), net on the Company’s consolidated statements of operations and comprehensive loss. The activities under the Regular Pension Plan are as follow: (in thousands) 2020 2019 Change in benefit obligation: Benefit obligation, beginning of year $ 560 $ 317 Service cost 186 94 Interest cost 5 6 Prior service cost 62 58 Actuarial loss (gain) 84 85 Benefit obligation, end of year 897 560 Change in plan assets: Fair value of plan assets, beginning of year 470 317 Company contributions 186 182 Expected net return on plan assets 4 2 Other costs (23 ) (30 ) Actuarial loss (1 ) (1 ) Fair value of plan assets, end of year 636 470 Funded status $ (261 ) $ (90 ) The underfunded amount of $261,000 and $90,000 is recognized in accrued liabilities on the consolidated balance sheet as of December 31, 2020 and 2019, respectively. In addition, $84,000 and $85,000 of actuarial loss is recognized in accumulated other comprehensive (loss) income for the years ended December 31, 2020 and December 31, 2019, respectively. The accumulated benefit obligation for the defined benefit plan was $0.9 million and $0.6 million as of December 31, 2020 and 2019, respectively. The weighted-average rates used to determine the net periodic benefit costs and projected benefit obligations were as follows: 2020 2019 Discount rate 0.40 % 0.90 % Rate of increased salary levels 1.80 % 1.80 % Expected long-term rate of return on assets 0.53 % 0.65 % The discount rate used in 2020 and 2019 is based on a yield curve constructed from a portfolio of high-quality, Euro-denominated fixed income investments with various maturities up to 12 years. Each year’s expected future benefit payments are discounted to their present value at the appropriate yield curve rate, thereby generating the overall discount rate for the projected benefit obligation. The expected long-term rate of return on plan assets is deemed to equal 0.75%, as guaranteed by the insurance company that holds the fund investments, less 0.1% of asset management fee, resulting in 0.65% prior to July 1, 2020, and a guaranteed rate of return of 0.5%, less 0.1% of asset management fee, resulting in 0.4% for all accruals after July 1, 2020. The fair values of the Regular Pension Plan assets as of December 31, 2020 and 2019 are as follows: Significant Unobservable Inputs (in thousands) (Level 3) 2020: Sundry liabilities $ - Insurance policies 706 Current account with insurer (70 ) $ 636 2019: Current account with insurer $ (15 ) Insurance policies 485 $ 470 The following table sets forth a summary of changes in fair value of the Regular Pension Plan assets for which fair value was determined by Level 3 inputs: (in thousands) 2020 2019 Unobservable inputs - beginning $ 470 $ 317 Actual return on plan assets 3 1 Net purchases, sales and settlements 186 182 Transfers out of Level 3 assets (23 ) (30 ) Unobservable inputs - ending $ 636 $ 470 The Company anticipates making $297,000 funding contributions to the Regular Pension Plan in 2021. Estimated future benefit payments are as follows: Fiscal year (in thousands): 2021 $ 6 2022 4 2023 4 2024 3 2025 3 2026−2030 23 $ 43 Defined benefit plans—Top Hat Plan In Aligos-Belgium, the Company established a pension bonus complementary plan (the Top Hat Plan), where the bonus payments to each participant are added to the Top Hat Plan. The annual contributions to this plan are based on performance and determined on a discretionary basis by the Company. The Top Hat Plan contains a legal yield guarantee of 1.75%. The Top Hat Plan became effective as of January 1, 2019. In 2019, the Company accounted for the Top Hat Plan in accordance with ASC 715— Compensation—Retirement Benefits Net periodic benefit costs and other amounts recognized in other comprehensive loss for the Top Hat Plan included the following components for the years ended December 31, 2020 and December 31, 2019, respectively: (in thousands) 2020 2019 Prior service costs $ 794 $ 348 Interest costs 8 5 Other costs 114 27 $ 916 $ 380 Net actuarial loss in plan asset and projected benefit obligation recognized in other comprehensive loss 52 32 Total recognized $ 968 $ 412 The net periodic benefit costs, excluding prior service costs, are included in other expenses on the Company’s consolidated statements of operations and comprehensive loss. The activities under the Top Hat Plan were as follow for the years ended December 31, 2020 and December 31, 2019, respectively: (in thousands) 2020 2019 Change in benefit obligation: Benefit obligation, beginning of year $ 649 $ 261 Prior service cost 834 348 Internal transfer 180 — Interest expense 8 5 Actuarial loss 58 35 Benefit obligation, end of year $ 1,729 $ 649 Change in plan assets: Fair value of plan assets, beginning of year $ 237 $ (20 ) Company contributions 496 281 Other costs (100 ) (27 ) Internal transfer (10 ) — Actuarial gain 6 3 Fair value of plan assets, end of year $ 629 $ 237 Funded status $ (1,100 ) $ (412 ) The underfunded amounts of $1.1 million and $412,000 is recognized in accrued liabilities on the consolidated balance sheet as of December 31, 2020 and December 31, 2019, respectively. In addition, $52,000 and $32,000 of actuarial loss is recognized in accumulated other comprehensive (loss) income for the years ended December 31, 2020 and December 31, 2019, respectively. The accumulated benefit obligation for the Top Hat Plan was $1.7 million and $0.6 million as of December 31, 2020 and December 31, 2019, respectively. The weighted-average rates used to determine the net periodic benefit costs and projected benefit obligations were as follows: 2020 2019 Discount rate 0.40 % 1.90 % Rate of increased salary levels 1.80 % 1.80 % Expected long-term rate of return on assets 0.00 % 0.00 % The discount rate used in 2020 and 2019 is based on a yield curve constructed from a portfolio of high-quality, Euro-denominated fixed income investments with various maturities up to 12 years. Each year’s expected future benefit payments are discounted to their present value at the appropriate yield curve rate, thereby generating the overall discount rate for the projected benefit obligation. The expected long-term rate of return on plan assets is deemed to equal 0.00%, as there is no guarantee of return from the insurance company holding the investments. The fair values of the Top Hat Plan assets as of December 31, 2020 and December 31, 2019 were as follows: Significant Unobservable Inputs (Level 3) (in thousands) 2020 2019 Sundry liabilities $ (797 ) $ (27 ) Insurance policies 1,426 264 $ 629 $ 237 The following table sets forth a summary of changes in fair value of the Top Hat Plan assets in 2020 and 2019 for which fair value was determined by Level 3 inputs: (in thousands) 2020 2019 Unobservable inputs - beginning $ 237 $ (20 ) Actual return on plan assets 6 3 Net purchases, sales and settlements 496 281 Transfers out of Level 3 assets (110 ) (27 ) Unobservable inputs - ending $ 629 $ 237 The Company anticipates making $0.6 million in funding contributions to the Top Hat Plan in 2021. Estimated future benefit payments are as follows: Fiscal year (in thousands): 2020 2019 2021 $ 4 $ 2 2022 4 2 2023 4 2 2024 4 2 2025 5 2 2026 - 2030 39 10 $ 60 $ 20

Net loss per share

Net loss per share	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Net loss per share	15. Net loss per share The following table summarizes the computation of basic and diluted net loss per share of the Company: Year Ended December 31, 2020 2019 Net loss $ (108,543 ) $ (52,264 ) Weighted average common stock outstanding, basic and diluted 9,988,191 2,007,173 Net loss per share – basic and diluted $ (10.87 ) $ (26.04 ) The Company’s potentially dilutive securities, which include redeemable convertible preferred stock, forward contracts to issue Preferred Stock, options to purchase common stock and unvested restricted stock, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of shares of Common Stock outstanding used to calculate both basic and diluted net loss per share is the same. The Company excluded the following potential shares of Common Stock, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: Year Ended December 31, 2020 2019 Convertible preferred stock — 19,163,877 Forward contract to issue convertible preferred stock — 3,569,630 Options to purchase common stock 3,344,765 884,623 Unvested restricted stock 408,396 827,187 Warrants to purchase preferred stock — 120,701 3,753,161 24,566,018

Subsequent events

Subsequent events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent events	16. Subsequent events The Company has evaluated all events occurring past the balance sheet date, during which time, nothing has occurred outside the normal course of business operations that would require disclosure.

Summary of significant accoun_2

Summary of significant accounting policies (Policies)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (U.S. GAAP) and include all adjustments necessary for the fair presentation of the Company’s financial position for the periods presented. Any reference in these notes to applicable accounting guidance is meant to refer to the authoritative U.S. GAAP included in the Accounting Standards Codification (ASC), and Accounting Standards Update (ASU) issued by the Financial Accounting Standards Board (FASB).
Principles of consolidation	Principles of consolidation The accompanying consolidated financial statements include Aligos-US and its wholly owned subsidiaries Aligos-Belgium and Aligos-Australia. All intercompany balances and transactions have been eliminated.
Use of estimates	Use of estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP generally requires management to make certain estimates and assumptions that affect the reported amounts in the consolidated financial statements and accompanying notes. The Company regularly evaluates estimates and assumptions related to assets and liabilities, at the dates of the consolidated financial statements and the reported amounts of expenses during the reporting period. Areas where management uses subjective judgments include, but are not limited to, right-of-use assets, lease obligations, impairment of long-lived assets, stock-based compensation, accrued research and development costs, pension liabilities, derivative liabilities and redeemable convertible preferred stock liability in the accompanying consolidated financial statements. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ materially from these estimates under different assumptions or conditions.
Foreign currency	Foreign currency The Company’s foreign subsidiaries use the U.S. dollar as their functional currency, and they initially measure the foreign currency denominated assets and liabilities at the transaction date. Monetary assets and liabilities are then re-measured at exchange rates in effect at the end of each period, and non-monetary assets and liabilities are converted at historical rates. A re-measurement gain was recognized during the year ended December 31, 2020 of $121,000 and a re-measurement loss was recognized during the year ended December 31, 2019 of
Segment information	Segment information The Company has determined that the Chief Executive Officer is its Chief Operating Decision Maker. The Company’s Chief Executive Officer reviews financial information presented on a consolidated basis for the purposes of assessing the performance and making decisions on how to allocate resources. Accordingly, the Company has determined that it operates in a single reportable segment. No revenue has been generated since inception. The Company has $6.6 million and $1.4 million of fixed assets in Aligos-US and Aligos-Belgium, respectively, as of December 31, 2020 and $7.3 million and $1.2 million of fixed assets in Aligos-US and Aligos‑Belgium, respectively as of December 31, 2019.
Cash equivalents	Cash equivalents The Company considers all highly liquid investments purchased with original maturities of 90 days or less at acquisition to be cash equivalents.
Restricted cash	Restricted cash As of December 31, 2020 and 2019, the restricted cash balance was $560,000 and $538,000, respectively, and was used to secure the letters of credit in relation to the Company’s operating leases and deposits on rental assets (Note 6).
Investments	Investments The Company determines the appropriate classification of debt securities at the time of purchase and re-evaluates such designation as of each balance sheet date. Debt securities are classified as held-to-maturity when the Company has the positive intent and ability to hold the securities to maturity, otherwise debt securities are classified as available-for sale. Held-to-maturity securities are carried at amortized cost. Available-for-sale debt securities are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale debt securities are reported as a separate component of stockholders’ deficit. Premiums or discounts from par value are amortized to investment income over the life of the underlying investment. The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in interest and other (expense) income, net within the condensed consolidated statements of operations and comprehensive loss. For both held-to-maturity and available-for-sale investments, the Company periodically reviews each individual security position that has an unrealized loss, or impairment, to determine if that impairment is other-than-temporary. If the Company believes an impairment of a security position is other than temporary, based on available quantitative and qualitative information as of the report date, the loss will be recognized as other income (expense) in the Company’s condensed consolidated statements of operations and a new cost basis in the investment is established. No impairment charges were recorded during the years ended December 31, 2020 and 2019. As of December 31, 2020 and 2019, short-term investments consisted of U.S. Treasury securities with original maturities of less than one year. As of December 31, 2019, long-term investments consisted of U.S. Treasury securities with original maturities of more than one year.
Deferred offering costs	Deferred offering costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. After consummation of the financing, these costs are recorded as a reduction of the proceeds received from the equity financing. If a planned equity financing is abandoned, the deferred offering costs are expensed immediately as a charge to operating expenses in the consolidated statement of operations and comprehensive loss. There were no deferred offering costs on the Company’s consolidated balance sheets at December 31, 2020 and 2019.
Concentrations of credit risk and significant suppliers	Concentrations of credit risk and significant suppliers The Company has no significant off-balance sheet risk, such as foreign exchange contracts, option contracts, or other foreign hedging arrangements. Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash, restricted cash and investments. Periodically, the Company maintains deposits in accredited financial institutions in excess of federally insured limits. The Company deposits its cash in financial institutions that it believes have high credit quality and has not experienced any losses on such accounts and does not believe it is exposed to any unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company generally invests its excess capital in money market funds, U.S. treasury bonds and U.S. treasury bills that are subject to minimal credit and market risks. The Company is dependent on various third parties to manufacture compounds for the Company to conduct research and studies for its programs. These programs would be adversely delayed by a significant interruption in the supply of active pharmaceutical ingredients.
Leases	Leases The Company determines if an arrangement is a lease at the inception of the lease. Operating leases are included in operating lease right-of-use (ROU) assets and operating lease liabilities in the consolidated balance sheet. Finance leases are included in property and equipment and finance lease liabilities in the consolidated balance sheet. ROU assets represent the right to use an underlying asset for the lease term and lease liabilities represent the obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. When the Company’s leases do not provide an implicit rate, an incremental borrowing rate is used based on the information available at the commencement dates in determining the present value of lease payments. The Company uses the implicit rate when readily determinable. The operating lease ROU assets also include any lease payments made and excludes lease incentives when paid by the Company or on the Company’s behalf. The Company’s lease terms may include the period covered by options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Lease expense for operating leases is recognized on a straight-line basis over the lease term. The Company has lease agreements with lease and non-lease components. The Company elected to not separate lease and non-lease components for all of its building leases. For vehicle leases, lease and non-lease components are accounted for separately. The Company also made an accounting policy election to recognize lease expense for leases with a term of 12 months or less on a straight-line basis over the lease term and not recognize ROU assets or lease liabilities for such leases.
Property and equipment	Property and equipment Property and equipment is stated at cost less accumulated depreciation, and is depreciated using the straight-line method over the estimated useful life of the asset, which are as follows: Lab equipment 3 years Computer equipment 3 years Furniture and office equipment 3-8 years Vehicles 4 years Leasehold improvements Shorter of the useful life or remaining lease term Expenditures for repairs and maintenance of assets are charged to expense as incurred. Upon retirement or sale, the cost and related accumulated depreciation of assets disposed of are removed from the accounts and any resulting gain or loss is included in loss from operations.
Impairment of long-lived assets	Impairment of long-lived assets The Company regularly reviews the carrying amount of its property, equipment and intangible assets to determine whether indicators of impairment may exist which warrant adjustments to carrying values or estimated useful lives. If indications of impairment exist, projected future undiscounted cash flows associated with the asset are compared to the carrying amount to determine whether the asset’s value is recoverable. If the carrying value of the asset exceeds such projected undiscounted cash flows, the asset will be written down to its estimated fair value. No impairment charges were recorded during the years ended December 31, 2020 or 2019.
Research and development expenses	Research and development expenses Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries, stock-based compensation and benefits, facilities costs, depreciation, and third-party license fees. Non-refundable prepayments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized. In-process research and development (IPR&D) expense represents the costs to acquire technologies to be used in research and development that have not reached technological feasibility or have no alternative future uses and thus are expensed as incurred. IPR&D expense also includes upfront license fees and milestones paid to collaborators for technologies with no alternative use.
Collaborative arrangements	Collaborative arrangements The Company enters into collaboration arrangements with pharmaceutical and other partners, under which the Company may grant licenses to its collaboration partners to research and develop potential drug candidates. Consideration under these contracts may include an upfront payment, development, regulatory, sales and other milestone payments. Contractual payments received for research and development activities performed are recognized on a gross basis in revenue from collaboration arrangements. The Company may also perform research and development activities under the collaboration agreements where the Company may be granted licenses from its collaboration partners. Contractual payments to the other party in collaboration agreements and costs incurred by the Company are recognized on a gross basis in research and development expenses. Royalties and license payments are recorded as due. When the Company enters into collaboration arrangements, the Company assesses whether the arrangement fall within the scope of ASC 808, Collaborative Arrangements Revenue from Contracts with Customers During the year ended December 31, 2019, no milestones were met and no royalties were due; therefore, the Company did not pay or expense any milestone or royalties. In the year ended December 31, 2020, a development milestone was met as the first patient dosing occurred and so the Company made a payment of $4.5 million, which is included in research and development in the consolidated statement of operations. The upfront payment received during the year ended December 31, 2020 was recorded on the consolidated balance sheet as deferred revenue from collaborations.
Fair value measurements	Fair value measurements Certain assets and liabilities of the Company are carried at fair value under U.S. GAAP. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: Level 1 —Quoted prices in active markets for identical assets or liabilities. Level 2 —Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. Level 3 —Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques.
Stock-based compensation	Stock-based compensation The Company’s stock-based awards consist of restricted stock awards and stock options. For stock-based awards issued to employees and nonemployees, the Company measures the estimated fair value of the stock-based awards on the date of grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the respective awards. The Company records expense for awards with service-based vesting using the straight-line method. The Company accounts for forfeitures as they occur. The Company classifies stock-based compensation expense in its consolidated statements of operations and comprehensive loss in the same manner in which the award recipient’s cash compensation costs are classified. The fair value of each restricted stock award is determined based on the number of shares granted and the value of the Company’s common stock on the date of grant. The fair value of each stock option award is estimated on the date of grant using the Black-Scholes option pricing model. The Black-Scholes option-pricing model requires the use of a number of assumptions including the fair value of the common stock, expected volatility, risk-free interest rate, expected dividends, and expected term of the option. The Company determined the expected stock volatility using a weighted-average of the historical volatility of a group of guideline companies that issued options with substantially similar terms, and expects to continue to do so until such time as the Company has adequate historical data regarding the volatility of its own traded stock price. The expected term of the Company’s stock options has been determined utilizing the simplified method for awards that qualify as “plain-vanilla” options. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. The Company has not paid, and does not anticipate paying, cash dividends on its common stock; therefore, the expected dividend yield is assumed to be zero. See Note 9 for the assumptions used by the Company in determining the grant date fair value of stock-based awards granted, as well as a summary of the stock-based award activity under the Company’s stock-based compensation plan for years ended December 31, 2020 and 2019.
Income taxes	Income taxes Deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Changes in deferred tax assets and liabilities are recorded in the provision for income taxes. The Company assesses the likelihood that its deferred tax assets will be recovered from future taxable income and, to the extent it believes, based upon the weight of available evidence, that it is more likely than not that all or a portion of the deferred tax assets will not be realized, a valuation allowance is established. The Company accounts for uncertain tax positions recognized in the consolidated financial statements by prescribing a more-likely-than-not threshold for financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The provision for income taxes includes the effects of any resulting tax reserves, or unrecognized tax benefits, that are considered appropriate as well as the related interest and penalties.
Net loss per share	Net loss per share 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 during the period, without consideration for potentially dilutive securities. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, redeemable convertible preferred stock, stock options, common stock subject to repurchase related to early exercise of stock options, unvested restricted stock subject to repurchase, warrants and convertible notes are considered to be potentially dilutive securities. The Company applies the two-class method to calculate its basic and diluted net loss per share as the Company has issued shares that meet the definition of participating securities. The two-class method is an earnings allocation formula that treats a participating security as having rights to earnings that otherwise would have been available to common stockholders. The Company’s participating securities contractually entitle the holders of such shares to participate in dividends, but do not contractually require the holders of such shares to participate in losses of the Company. Accordingly, in periods in which the Company reports a net loss, such losses are not allocated to such participating securities. Accordingly, in periods in which the Company reports a net loss, diluted net loss per share is the same as basic net loss per share, since dilutive common shares are not assumed to have been issued if their effect is anti-dilutive.
Benefit plans	Benefit plans The Company has established a defined contribution savings plan for its employees in Aligos-US under Section 401(k) of the Internal Revenue Code, and a defined benefits plan for its employees in Aligos-Belgium. The Company uses the standard method for the recognition of the actuarial results as described in ASC 715. This means application of a 10% corridor and amortization over the expected average remaining working lives of the employees. The plan contains benefits to the plan participant on the normal plan retirement date and benefits to the partner after death of the plan participant. This plan is recognized under ASC 715.
Recently adopted accounting pronouncements	Recently adopted accounting pronouncements In June 2018, the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting Compensation-Stock Compensation In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606) In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808)—Clarifying the Interaction between Topic 808 and Topic 606 In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230) Restricted Cash In March 2017, the FASB issued ASU No. 2017-07, Compensation-Retirement Benefits (ASC Topic 715) In August 2018, the FASB issued ASU No. 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20) In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework— Changes to the Disclosure Requirements for Fair Value Measurement
Recently issued accounting standards	Recently issued accounting standards In June 2016, the FASB issued ASU No. 2016-13. Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments Codification Improvements to Topic 326, Financial Instruments—Credit Losses Codification Improvements to Topic 326, Financial Instruments—Credit Losses Codification Improvements to Topic 326 Financial Instruments—Credit Losses In December 2019, the FASB issued ASU No. 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes From time to time, new accounting pronouncements are issued by FASB that the Company adopts as of the specified effective date. The Company qualifies as an “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has the option to not “opt out” of the extended transition related to complying with new or revised accounting standards. This means that when a standard is issued or revised and it has different application dates for public and nonpublic companies, the Company has the option to adopt the new or revised standard at the time nonpublic companies adopt the new or revised standard and can do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company.

Summary of significant accoun_3

Summary of significant accounting policies (Tables)	12 Months Ended
	Dec. 31, 2020
Accounting Policies [Abstract]
Summary of Estimated Useful Life of Asset	Property and equipment is stated at cost less accumulated depreciation, and is depreciated using the straight-line method over the estimated useful life of the asset, which are as follows: Lab equipment 3 years Computer equipment 3 years Furniture and office equipment 3-8 years Vehicles 4 years Leasehold improvements Shorter of the useful life or remaining lease term

Property and equipment (Tables)

Property and equipment (Tables)	12 Months Ended
	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Summary of Property and Equipment	The components of property and equipment were as follows as of December 31, 2020 and 2019: (in thousands) 2020 2019 Leasehold improvements $ 5,655 $ 5,100 Lab equipment 4,833 3,204 Computer equipment 942 890 Furniture and office equipment 459 425 Vehicles 296 296 Asset under construction 65 110 Total, at cost 12,250 10,025 Accumulated depreciation (4,243 ) (1,508 ) Total, net $ 8,007 $ 8,517

Investments (Tables)

Investments (Tables)	12 Months Ended
	Dec. 31, 2020
Debt Securities Available For Sale And Held To Maturity [Abstract]
Summary of Available For Sale and Held to Maturity Securities Amortized Cost Gross Unrealized Gains Losses and Fair Value	As of December 31, 2020 and 2019, amortized cost, gross unrealized gains and losses, and estimated fair values of total fixed-maturity securities were as follows: 2019 Gross Gross Amortized Unrealized Unrealized Estimated (in thousands) Cost Gain Loss Fair Value Held-to-maturity securities: U.S. Treasury bonds $ 58,117 $ 31 $ (1 ) $ 58,147 2020 Gross Gross Amortized Unrealized Unrealized Estimated (in thousands) Cost Gain Loss Fair Value Held-to-maturity securities: U.S. Treasury bonds $ 10,002 $ 14 $ — $ 10,016 Available-for-sale securities: U.S. Treasury bonds $ 13,060 $ 68 $ — $ 13,128 $ 23,062 $ 82 $ — $ 23,144
Summary of Amortized Cost and Estimated Fair Value of Fixed-maturity Securities	Amortized cost and estimated fair value of fixed-maturity securities at December 31, 2020 by contractual maturity were as follows: 2020 (in thousands) Amortized Cost Estimated Fair Value Amounts maturing in: One year or less $ 23,062 $ 23,144 More than one year — — Total investments $ 23,062 $ 23,144

Accrued liabilities (Tables)

Accrued liabilities (Tables)	12 Months Ended
	Dec. 31, 2020
Payables And Accruals [Abstract]
Summary of Accrued Liabilities	Accrued liabilities consisted of the following as of December 31: (in thousands) 2020 2019 Accrued compensation $ 7,274 $ 3,211 Accrued payables 8,554 3,113 Liability with early exercised stock options 569 753 Other 167 522 Total $ 16,564 $ 7,599

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2020
Leases [Abstract]
Summary of Maturities of Lease Liabilities	Maturities of lease liabilities as of December 31, 2020, were as follows: (in thousands) Operating Lease Finance Lease Year ending December 31: 2021 $ 2,616 $ 80 2022 2,700 79 2023 2,696 42 2024 2,678 1 2025 2,772 — Thereafter 3,642 — 17,104 202 Less: imputed interest (4,291 ) (8 ) Present value of lease liabilities 12,813 194 Less: current portion (2,442 ) (64 ) Lease liabilities net of current portion $ 10,371 $ 130
Summary of Components of lease Expense	The components of lease expense were as follows for the years ended December 31, 2020 and 2019: (in thousands) 2020 2019 Operating lease cost $ 1,847 $ 2,228 Finance lease cost: Amortization of right-of-use assets 60 46 Interest on lease liabilities 9 6 Total finance lease cost $ 69 $ 52 Short-term lease cost $ 15 $ 11
Summary of Additional Information Related to the Leases	Additional information related to the Company’s leases was as follows as of December 31: 2020 2019 Operating Lease: Weighted-average remaining lease term (years) 5.97 7.10 Weighted-average discount rate 9.35 % 9.34 % Finance Lease: Weighted-average remaining lease term (years) 2.68 3.66 Weighted-average discount rate 3.15 % 3.18 %

Stock-based compensation (Table

Stock-based compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Summary of Assumptions Used to Determine Grant-date Fair Value of Stock Options	The assumptions that the Company used to determine the grant-date fair value of stock options granted to Participants were as follows, presented on a weighted-average basis: 2020 2019 Expected term (in years) 5.79 6.06 Risk-free interest rate 0.93% 1.94% Dividend yield — — Volatility 77.14% 60.24%
Summary of Stock Options	Stock option activity during the year ended December 31, 2020 and 2019 was as follows: Number of Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding as of December 31, 2018 1,062,457 $ 1.30 9.88 $ — Granted 178,863 $ 1.30 Exercised (891,229 ) $ 1.30 37 Forfeited (3,219 ) $ 1.30 Outstanding as of December 31, 2019 346,872 $ 1.30 9.01 $ 744 Granted 5,382,362 $ 11.42 Exercised (188,990 ) $ 2.33 810 Forfeited (52,096 ) $ 1.76 Outstanding as of December 31, 2020 5,488,148 $ 11.19 9.57 $ 90,335 Options vested and expected to vest as of December 31, 2020 5,427,891 $ 11.28 9.58 $ 88,881 Options vested and exercisable as of December 31, 2020 464,567 $ 3.20 8.95 $ 11,360 Options vested and expected to vest as of December 31, 2019 884,623 $ 1.30 9.01 $ 1,896 Options vested and exercisable as of December 31, 2019 31,330 $ 1.30 8.88 $ 67
Summary of Stock Based Compensation Expense Was Allocated	Stock-based compensation expense was allocated as follows for the years ended December 31, 2020 and December 31, 2019: (in thousands) 2020 2019 Research and development $ 1,041 $ 462 General and administrative 1,934 290 Total $ 2,975 $ 752
Restricted Stock [Member]
Summary of Stock Options	The following table summarizes the Company’s restricted common stock activity for years ended December 31, 2020 and 2019: Number of Awards Weighted- Average Grant Date Fair Value Aggregate Fair Value Issued and unvested as of December 31, 2018 1,521,387 $ 0.94 1,430 Restricted stock awards granted — $ — — Restricted stock awards vested (694,200 ) $ 0.86 (596 ) Issued and unvested as of December 31, 2019 827,187 $ 1.01 $ 834 Restricted stock awards granted — — Restricted stock awards vested (418,776 ) $ 0.86 (361 ) Issued and unvested as of December 31, 2020 408,411 $ 1.16 $ 473

Fair value (Tables)

Fair value (Tables)	12 Months Ended
	Dec. 31, 2020
Summary of fair value of the financial instruments that are measured at fair value on a recurring basis	The following tables present the fair value of the Company’s financial instruments that are measured or disclosed at fair value on a recurring basis: Fair Value Measurements as of December 31, 2020 (in thousands) Level 1 Level 2 Level 3 Assets: Cash and cash equivalents $ 220,383 $ — $ — U.S. Treasury bonds 23,144 — — $ 243,527 $ — $ — Fair Value Measurements as of December 31, 2019 (in thousands) Level 1 Level 2 Level 3 Assets: Cash and cash equivalents $ 69,565 $ — $ — U.S. Treasury bonds 58,147 — — Liabilities: Warrants — — (461 ) Convertible Preferred Stock Liability — — (3,174 ) $ 127,712 $ — $ (3,635 )
Summary of changes in fair value for which fair value was determined by Level 3 inputs	The following table sets forth a summary of changes in fair value of the Company’s derivative liability for which fair value was determined by Level 3 inputs: Warrants Redeemable Convertible Preferred Stock Liability Balance as of December 31, 2018 $ 861 $ — Exercise of warrants (52 ) — Change in fair value (348 ) 3,174 Balance as of December 31, 2019 $ 461 $ 3,174 Exercise of warrants (137 ) — Change in fair value 296 11,386 Retirement of liability (620 ) (14,560 ) Balance as of December 31, 2020 $ — $ —
Mandatorily Redeemable Preferred Stock [Member]
Schedule of Fair Value Measurement Valuation Assumptions	The Redeemable Convertible Preferred Stock Liability was measured at fair value under the following assumptions through redemption on October 6, 2020 and as of December 31, 2019: 2020 2019 Exercise price $ 11.21 $ 11.21 Term (in years) 0.02-0.75 1.27 Risk-free interest rate 0.08%-0.11% 1.55% Dividend yield — — Volatility —% 60.00%
Warrant [Member]
Schedule of Fair Value Measurement Valuation Assumptions	The Warrants were measured at fair value under the following assumption as of December 31, 2019: 2020 2019 Exercise price $ 9.32 $ 9.32 Term (in years) 0.32 2.00 - 3.00 Risk-free interest rate 0.10 % 1.63 % Dividend yield — — Volatility 120.00 % 75.00 %

Income taxes (Tables)

Income taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Schedule of Components of Current Provision for Income Taxes	The components of the current provision for income taxes were as follows for the years ended December 31, 2020 and 2019: (in thousands) 2020 2019 Current: State $ 1 $ 1 Federal - $ - Foreign 160 $ 85 Total current provision for income taxes $ 161 $ 86 Deferred: State $ — $ — Federal — — Foreign — — Total deferred provision for income taxes $ — $ —
Schedule of Expected Income Tax (Benefit) Computed Using Federal Statutory Income Tax Rate to Company's Effective Income Tax Rate	A reconciliation of the expected income tax (benefit) computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows for the years ended December 31, 2020 and 2019: 2020 2019 Income tax computed at federal statutory rate 21.00 % 21.00 % State taxes, net of federal benefit 6.90 % 8.18 % R&D credit carryovers 1.40 % 1.87 % Change in valuation allowance (27.24 )% (29.71 )% Permanent differences (0.17 )% (1.32 )% Change in fair value of derivatives (2.25 )% — Other 0.21 % (0.18 )% Effective income tax rate (0.15 )% (0.16 )%
Schedule of Deferred Tax Assets And Liabilities	The components of the deferred tax assets and liabilities were as follows at December 31: (in thousands) 2020 2019 Deferred tax assets: Federal net operating loss carryforward $ 31,233 $ 12,106 State net operating loss carryforward 10,664 4,227 Foreign net operating loss carryforward 33 — Operating lease liabilities 4,453 3,776 Tax credits 4,639 1,865 Other accruals and reserves 1,558 675 Stock-based compensation 209 — Other 10 7 52,799 22,656 Valuation allowance (49,133 ) (19,362 ) Net deferred tax assets $ 3,666 $ 3,294 Deferred tax liabilities: Right of use assets $ (2,857 ) $ (2,067 ) Stock-based compensation — (115 ) Property and equipment (809 ) (1,112 ) Total deferred tax liabilities $ (3,666 ) $ (3,294 ) Total deferred income taxes $ — $ —
Summary of Changes to Unrecognized Tax Benefits	The following table summarizes the changes to the Company’s unrecognized tax benefits: (in thousands) 2020 2019 Balance, beginning of the period $ 637 $ 79 Increase related to prior year positions 131 — Increase related to current year positions 768 558 Balance, ending of the period $ 1,536 $ 637

Benefit plans (Tables)

Benefit plans (Tables)	12 Months Ended
	Dec. 31, 2020
Regular Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Summary of Net Periodic Benefit Costs and Other Amounts Recognized in Other Comprehensive Loss	Net periodic benefit costs and other amounts recognized in other comprehensive loss for the Regular Pension Plan include the following components for the years ended December 31, 2020 and December 31, 2019: (in thousands) 2020 2019 Service cost $ 186 $ 94 Expected return on plan assets (4 ) (2 ) Interest costs 5 6 Amortization of actuarial gains/(losses) 2 - Other costs 46 29 Prior service costs 33 58 268 185 Net actuarial loss (gain) in plan asset and projected benefit obligation recognized in other comprehensive loss 82 86 Total recognized $ 350 $ 271
Summary of Activities Under Pension Plan	The activities under the Regular Pension Plan are as follow: (in thousands) 2020 2019 Change in benefit obligation: Benefit obligation, beginning of year $ 560 $ 317 Service cost 186 94 Interest cost 5 6 Prior service cost 62 58 Actuarial loss (gain) 84 85 Benefit obligation, end of year 897 560 Change in plan assets: Fair value of plan assets, beginning of year 470 317 Company contributions 186 182 Expected net return on plan assets 4 2 Other costs (23 ) (30 ) Actuarial loss (1 ) (1 ) Fair value of plan assets, end of year 636 470 Funded status $ (261 ) $ (90 )
Summary of Weighted-average Rates used to Determine Net Periodic Benefit Costs and Projected Benefit Obligations	The weighted-average rates used to determine the net periodic benefit costs and projected benefit obligations were as follows: 2020 2019 Discount rate 0.40 % 0.90 % Rate of increased salary levels 1.80 % 1.80 % Expected long-term rate of return on assets 0.53 % 0.65 %
Summary of Fair Values of Pension Plan Assets	The fair values of the Regular Pension Plan assets as of December 31, 2020 and 2019 are as follows: Significant Unobservable Inputs (in thousands) (Level 3) 2020: Sundry liabilities $ - Insurance policies 706 Current account with insurer (70 ) $ 636 2019: Current account with insurer $ (15 ) Insurance policies 485 $ 470
Summary of Changes in Fair Value of Regular Pension Plan Assets	The following table sets forth a summary of changes in fair value of the Regular Pension Plan assets for which fair value was determined by Level 3 inputs: (in thousands) 2020 2019 Unobservable inputs - beginning $ 470 $ 317 Actual return on plan assets 3 1 Net purchases, sales and settlements 186 182 Transfers out of Level 3 assets (23 ) (30 ) Unobservable inputs - ending $ 636 $ 470
Summary of Estimated Future Benefit Payments	Estimated future benefit payments are as follows: Fiscal year (in thousands): 2021 $ 6 2022 4 2023 4 2024 3 2025 3 2026−2030 23 $ 43
Top Hat Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Summary of Net Periodic Benefit Costs and Other Amounts Recognized in Other Comprehensive Loss	Net periodic benefit costs and other amounts recognized in other comprehensive loss for the Top Hat Plan included the following components for the years ended December 31, 2020 and December 31, 2019, respectively: (in thousands) 2020 2019 Prior service costs $ 794 $ 348 Interest costs 8 5 Other costs 114 27 $ 916 $ 380 Net actuarial loss in plan asset and projected benefit obligation recognized in other comprehensive loss 52 32 Total recognized $ 968 $ 412
Summary of Activities Under Pension Plan	The activities under the Top Hat Plan were as follow for the years ended December 31, 2020 and December 31, 2019, respectively: (in thousands) 2020 2019 Change in benefit obligation: Benefit obligation, beginning of year $ 649 $ 261 Prior service cost 834 348 Internal transfer 180 — Interest expense 8 5 Actuarial loss 58 35 Benefit obligation, end of year $ 1,729 $ 649 Change in plan assets: Fair value of plan assets, beginning of year $ 237 $ (20 ) Company contributions 496 281 Other costs (100 ) (27 ) Internal transfer (10 ) — Actuarial gain 6 3 Fair value of plan assets, end of year $ 629 $ 237 Funded status $ (1,100 ) $ (412 )
Summary of Weighted-average Rates used to Determine Net Periodic Benefit Costs and Projected Benefit Obligations	The weighted-average rates used to determine the net periodic benefit costs and projected benefit obligations were as follows: 2020 2019 Discount rate 0.40 % 1.90 % Rate of increased salary levels 1.80 % 1.80 % Expected long-term rate of return on assets 0.00 % 0.00 %
Summary of Fair Values of Pension Plan Assets	The fair values of the Top Hat Plan assets as of December 31, 2020 and December 31, 2019 were as follows: Significant Unobservable Inputs (Level 3) (in thousands) 2020 2019 Sundry liabilities $ (797 ) $ (27 ) Insurance policies 1,426 264 $ 629 $ 237
Summary of Changes in Fair Value of Regular Pension Plan Assets	The following table sets forth a summary of changes in fair value of the Top Hat Plan assets in 2020 and 2019 for which fair value was determined by Level 3 inputs: (in thousands) 2020 2019 Unobservable inputs - beginning $ 237 $ (20 ) Actual return on plan assets 6 3 Net purchases, sales and settlements 496 281 Transfers out of Level 3 assets (110 ) (27 ) Unobservable inputs - ending $ 629 $ 237
Summary of Estimated Future Benefit Payments	Estimated future benefit payments are as follows: Fiscal year (in thousands): 2020 2019 2021 $ 4 $ 2 2022 4 2 2023 4 2 2024 4 2 2025 5 2 2026 - 2030 39 10 $ 60 $ 20

Net loss per share (Tables)

Net loss per share (Tables)	12 Months Ended
	Dec. 31, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table summarizes the computation of basic and diluted net loss per share of the Company: Year Ended December 31, 2020 2019 Net loss $ (108,543 ) $ (52,264 ) Weighted average common stock outstanding, basic and diluted 9,988,191 2,007,173 Net loss per share – basic and diluted $ (10.87 ) $ (26.04 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The Company excluded the following potential shares of Common Stock, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: Year Ended December 31, 2020 2019 Convertible preferred stock — 19,163,877 Forward contract to issue convertible preferred stock — 3,569,630 Options to purchase common stock 3,344,765 884,623 Unvested restricted stock 408,396 827,187 Warrants to purchase preferred stock — 120,701 3,753,161 24,566,018

Organization - Additional Infor

Organization - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Nov. 05, 2020	Oct. 20, 2020	Oct. 20, 2020	Oct. 08, 2020	Dec. 31, 2020	Dec. 31, 2019
Nature Of Operations [Line Items]
Reverse stock split				1-for-9.3197	Effective immediately on filing date, the Company converted all shares of Common Stock into 0.90144231 shares of Common Stock (the 2018 Reverse Stock Split).
Common Stock, Shares, Issued					36,606,247	3,927,803
Accumulated deficit					$ 174,740	$ 66,197
Unrestricted cash, Cash equivalent and short term investment					$ 243,500
Conversion Of Stock Voting Shares [Member]
Nature Of Operations [Line Items]
Temporary equity shares converted into permanent equity		19,761,870
Conversion Of Stock Non Voting Shares [Member]
Nature Of Operations [Line Items]
Temporary equity shares converted into permanent equity		3,092,338
IPO
Nature Of Operations [Line Items]
Stock issued during the period new issues shares			10,000,000
Sale of stock issue price per share		$ 15	$ 15
Sale of stock net consideration received on the transaction			$ 135,400
Underwriting discounts and commissions			10,500
Offer expenses			$ 4,100
Over-Allotment Option [Member]
Nature Of Operations [Line Items]
Sale of stock net consideration received on the transaction	$ 16,000
Underwriting discounts and commissions	$ 1,200
Common Stock, Shares, Issued	1,150,000

Summary of significant accoun_4

Summary of significant accounting policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2020USD ($)Segment	Dec. 31, 2019USD ($)
Financing Sources [Line Items]
Re-measurement gain (loss)	$ 121,000	$ (47,000)
Number of reportable segments | Segment	1
Revenue	$ 0
Property and equipment, net	$ 8,007,000	8,517,000
Cash equivalent qualification, description	The Company considers all highly liquid investments purchased with original maturities of 90 days or less at acquisition to be cash equivalents.
Restricted cash	$ 560,000	538,000
Other than temporary impairment losses, investments	0	0
Deferred offering costs	0	0
Impairment of long lived assets	0	0
Royalties due		0
Expenses on milestone payments		0
Dividends, common stock, cash	$ 0
Expected dividend yield	0.00%
Percentage of expected average remaining working lives of employees	10.00%
Research and Development
Financing Sources [Line Items]
Expenses on milestone payments	$ 4,500,000
US
Financing Sources [Line Items]
Property and equipment, net	6,600,000	7,300,000
Belgium
Financing Sources [Line Items]
Property and equipment, net	$ 1,400,000	$ 1,200,000

Summary of significant accoun_5

Summary of significant accounting policies - Summary of Estimated Useful Life of Asset (Detail)	12 Months Ended
	Dec. 31, 2020
Lab Equipment [Member]
Property Plant And Equipment [Line Items]
Estimated useful life of asset	3 years
Computer Equipment [Member]
Property Plant And Equipment [Line Items]
Estimated useful life of asset	3 years
Vehicles [Member]
Property Plant And Equipment [Line Items]
Estimated useful life of asset	4 years
Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Estimated useful life of asset	Shorter of the useful life or remaining lease term
Minimum [Member] | Furniture and Office Equipment [Member]
Property Plant And Equipment [Line Items]
Estimated useful life of asset	3 years
Maximum [Member] | Furniture and Office Equipment [Member]
Property Plant And Equipment [Line Items]
Estimated useful life of asset	8 years

Property and equipment - Summar

Property and equipment - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Total, at cost	$ 12,250	$ 10,025
Accumulated depreciation	(4,243)	(1,508)
Total, net	8,007	8,517
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Total, at cost	5,655	5,100
Lab equipment [Member]
Property, Plant and Equipment [Line Items]
Total, at cost	4,833	3,204
Computer equipment [Member]
Property, Plant and Equipment [Line Items]
Total, at cost	942	890
Furniture and office equipment [Member]
Property, Plant and Equipment [Line Items]
Total, at cost	459	425
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Total, at cost	296	296
Asset under construction [Member]
Property, Plant and Equipment [Line Items]
Total, at cost	$ 65	$ 110

Property and equipment - Additi

Property and equipment - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Abstract]
Depreciation expense	$ 2,735	$ 1,396

Investments - Summary of Availa

Investments - Summary of Available For Sale and Held to Maturity Securities Amortized Cost Gross Unrealized Gains Losses and Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale And Held To Maturity Securities Amortised Cost Gross Unrealised Gains Losses And Fair Value [Line Items]
Held-to-maturity securities, Amortized Cost	$ 23,062
Held-to-maturity securities, Estimated Fair Value	23,144
Total Held-to-maturity securities and Available for-sale securities Amortized Cost	23,062
Total Held-to-maturity securities and Available for-sale securities Gross Unrealized Gain	82
Total Held-to-maturity securities and Available for-sale securities Estimated Fair Value	23,144
U.S. Treasury bonds [Member]
Schedule Of Available For Sale And Held To Maturity Securities Amortised Cost Gross Unrealised Gains Losses And Fair Value [Line Items]
Held-to-maturity securities, Amortized Cost	10,002	$ 58,117
Held-to-maturity securities, Gross Unrealized Gain	14	31
Held-to-maturity securities, Gross Unrealized Loss		(1)
Held-to-maturity securities, Estimated Fair Value	10,016	$ 58,147
Available-for-sale securities, Amortized Cost	13,060
Available-for-sale securities, Gross Unrealized Gain	68
Available-for-sale securities, Estimated Fair Value	$ 13,128

Investments - Summary of Amorti

Investments - Summary of Amortized Cost and Estimated Fair Value of Fixed-maturity Securities (Detail) $ in Thousands	Dec. 31, 2020USD ($)
Debt Securities Available For Sale And Held To Maturity [Abstract]
Fixed-Maturity Securities, Amortized Cost, One year or less	$ 23,062
Held-to-maturity securities, Amortized Cost	23,062
Fixed-Maturity Securities, Estimated Fair Value, One year or less	23,144
Fixed-Maturity Securities, Estimated Fair Value, Total investments	$ 23,144

Investments - Additional Inform

Investments - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fixed-Maturity Securities [Member]
Investment In Available For Sale And Held To Maturity Securities [Line Items]
Interest income	$ 1.2	$ 1.6

Accrued liabilities - Summary o

Accrued liabilities - Summary of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued compensation	$ 7,274	$ 3,211
Accrued payables	8,554	3,113
Liability with early exercised stock options	569	753
Other	167	522
Total	$ 16,564	$ 7,599

Leases - Additional Information

Leases - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lessee Lease Description [Line Items]
Operating lease, payments	$ 2,500	$ 1,200
Finance lease right of use assets	296,000	296,000
Finance lease right of use assets accumulated amortization	$ 107,000	$ 47,000
Minimum [Member]
Lessee Lease Description [Line Items]
Operating and finance lease remaining lease term	4 years
Operating lease option to extend	5 years
Maximum [Member]
Lessee Lease Description [Line Items]
Operating and finance lease remaining lease term	8 years 6 months
Operating lease option to extend	8 years

Leases - Summary of Maturities

Leases - Summary of Maturities of Lease Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating Lease
2021	$ 2,616
2022	2,700
2023	2,696
2024	2,678
2025	2,772
Thereafter	3,642
Lessee, Operating Lease, Liability, to be Paid	17,104
Less: imputed interest	(4,291)
Present value of lease liabilities	12,813
Less: current portion	(2,442)	$ (2,378)
Lease liabilities net of current portion	10,371	11,701
Finance Lease
2021	80
2022	79
2023	42
2024	1
Finance Lease, Liability, Payment, Due	202
Less: imputed interest	(8)
Present value of lease liabilities	194
Less: current portion	(64)	(74)
Lease liabilities net of current portion	$ 130	$ 178

Leases - Summary of Components

Leases - Summary of Components of Lease Expense (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Lease Cost [Abstract]
Operating lease cost	$ 1,847	$ 2,228
Finance lease cost:
Amortization of right-of-use assets	60	46
Interest on lease liabilities	9	6
Total finance lease cost	69	52
Short-term lease cost	$ 15	$ 11

Leases - Summary of Additional

Leases - Summary of Additional Information Related to the leases (Detail)	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Additional Information Related To The Leases [Abstract]
Weighted-average remaining lease term (years)	5 years 11 months 19 days	7 years 1 month 6 days
Weighted-average discount rate	9.35%	9.34%
Weighted-average remaining lease term (years)	2 years 8 months 4 days	3 years 7 months 28 days
Weighted-average discount rate	3.15%	3.18%

Derivative liabilities and re_2

Derivative liabilities and redeemable convertible preferred stock liability - Additional Information (Detail) - USD ($)	Oct. 19, 2020	Dec. 23, 2019	Dec. 31, 2020	Dec. 31, 2019	Aug. 16, 2018	Jun. 06, 2018	Apr. 20, 2018
Derivative Liabilities And Convertible Preferred Stock Liability [Line Items]
Class of warrant or right, number of securities called by warrants or rights			134,112
Percentage of principal amount of notes covered by warrants			25.00%
Warrants issued expiry period			10 years
Warrants issued closing date			Apr. 20, 2018
Changes in fair value of the warrants			$ 757,000	$ 51,000
Derivative Financial Instruments, Liabilities [Member]
Derivative Liabilities And Convertible Preferred Stock Liability [Line Items]
Changes in fair value of the warrants			296,000	348,000
Derivative Financial Instruments, Liabilities [Member] | Warrant [Member]
Derivative Liabilities And Convertible Preferred Stock Liability [Line Items]
Fair value of warrants upon issuance						$ 238,000,000	$ 700,000
Fair value of the warrants			$ 0	461,000,000
Mandatorily Redeemable Preferred Stock [Member]
Derivative Liabilities And Convertible Preferred Stock Liability [Line Items]
Redeemable convertible preferred stock liability at a fair value		$ 3,200,000		$ 3,200,000
Redeemable Convertible Preferred Stock shares issued				0
Series A
Derivative Liabilities And Convertible Preferred Stock Liability [Line Items]
Warrants exercise price per share			$ 9.32
Sale of stock issue price per share					$ 9.32
Series A | Derivative Financial Instruments, Liabilities [Member]
Derivative Liabilities And Convertible Preferred Stock Liability [Line Items]
Warrants exercised				13,411
Warrants outstanding				120,701
Series B Two Preferred Stock [Member]
Derivative Liabilities And Convertible Preferred Stock Liability [Line Items]
Sale of Stock, Number of Shares Issued in Transaction	3,569,630	3,569,630
Sale of stock issue price per share		$ 11.20563
Change in fair value of liability		$ 11,400,000
Maximum [Member]
Derivative Liabilities And Convertible Preferred Stock Liability [Line Items]
Warrants issued closing date			Jun. 6, 2018

Capital stock - Additional Info

Capital stock - Additional Information (Detail) $ / shares in Units, $ in Thousands	Oct. 19, 2020shares	Oct. 08, 2020	Dec. 23, 2019USD ($)$ / sharesshares	Sep. 19, 2018USD ($)	Aug. 16, 2018USD ($)$ / shares	Aug. 15, 2018$ / sharesshares	Jul. 23, 2018shares	Mar. 19, 2018$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2020$ / sharesshares	Oct. 20, 2020$ / sharesshares	Dec. 31, 2019$ / sharesshares	Feb. 05, 2018$ / sharesshares
Date of incorporation										Feb. 5, 2018
Number of shares of common stock authorized			278,000,000			149,000,000	25,000,000		320,000,000	320,000,000	320,000,000	278,000,000	20,000,000
Common Stock, Par Value | $ / shares									$ 0.000001	$ 0.000001		$ 0.000001	$ 0.0001
Common Stock, Shares, Issued									36,606,247	36,606,247		3,927,803
Number of shares of preferred stock authorized			212,994,964			102,500,000			10,000,000	10,000,000	10,000,000
Preferred stock authorized par value | $ / shares			$ 0.0001			$ 0.0001					$ 0.0001
Reverse stock split ratio						0.90144231
Reverse stock split		1-for-9.3197							Effective immediately on filing date, the Company converted all shares of Common Stock into 0.90144231 shares of Common Stock (the 2018 Reverse Stock Split).
Common stock voting right			one
Preferred Stock, Conversion split					one-for-one
Temporary Equity, Shares Issued									0	0
Series A Preferred Stock [Member]
Number of shares of preferred stock authorized			101,962,864						0	0		101,962,864
Sale of stock issue price per share | $ / shares					$ 9.32
Sale of stock, consideration received on transaction | $				$ 20,000	$ 75,000
Temporary Equity, Shares Issued									0	0		10,819,843
Series B One Preferred Stock [Member]
Number of shares of preferred stock authorized			77,764,055
Sale of stock issue price per share | $ / shares			$ 10.18690
Sale of stock, consideration received on transaction | $			$ 85,000
Stock issuance costs | $									$ 442,000
Sale of Stock, Number of Shares Issued in Transaction			8,344,034
Series B Preferred Stock [Member]
Number of shares of preferred stock authorized			33,268,045						0	0		77,764,055
Sale of stock, consideration received on transaction | $			$ 125,000
Temporary Equity, Shares Issued									0	0		8,344,034
Voting Common Stock [Member]
Number of shares of common stock authorized											300,000,000
Non-Voting Common Stock [Member]
Number of shares of common stock authorized											20,000,000
Series A [Member]
Conversion of convertible notes to redeemable convertible preferred stock | $					5,600
Stock issuance costs | $					$ 194,000
Series B Two Preferred Stock [Member]
Sale of stock issue price per share | $ / shares			$ 11.20563
Sale of Stock, Number of Shares Issued in Transaction	3,569,630		3,569,630
Cummulative stock issued			0
Two Founder and One Employee [Member]
Number of shares issued								425,585
Sale of stock issue price per share | $ / shares								$ 0.001
Common stock vesting period								3 years
Vesting period description									The shares were purchased for a de-minimis amount on the grant date and the shares vest monthly over a three-year period after a one-year cliff.
Common stock vesting cliff period								1 year
Additional shares issued							77,379
Restricted Stock [Member] | Two Founders [Member]
Common Stock, Shares, Issued								1,508,900
Sale of stock issue price per share | $ / shares								$ 0.001
Share price | $ / shares								$ 2

Stock-based Compensation - Addi

Stock-based Compensation - Additional Information (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019USD ($)$ / sharesshares	Dec. 31, 2018shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based payment exercise price description	The exercise price for incentive stock options is at least 100% of the fair market value on the date of grant for stockholders owning less than 10% of the voting power of all classes of stock, or at least 110% of the fair market value for stockholders owning more than 10% of the voting power of all classes of stock. Options generally expire in 10 years and vest over periods determined by the Board, generally 48 months.
Share based compensation expense | $	$ 2,975	$ 752
Share based compensation expense recognized tax benefit | $	$ 0	$ 0
Shares of common stock held by employees subject to repurchase	396,522	577,124
Share price | $ / shares	$ 600,000	$ 700,000
Less than 10% [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price for incentive stock options as of fair market value	1
More Than 10% [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price for incentive stock options as of fair market value	1.10
Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration period	10 years
Common stock vesting period	48 months
Share based compensation expense | $	$ 2,600	$ 261
Share based payment unamortised share based payment expenses | $	$ 38,800
Share based payment expenses amortized over a weighted average period	3 years 5 months 4 days
Share based payments weighted-average grant date fair value | $ / shares	$ 7.50	$ 0.08
Common stock issued upon exercise of stock options	371,939	537,781
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration period	3 years
Share based compensation expense | $	$ 361	$ 492
Share based payment unamortised share based payment expenses | $	$ 526
Share based payment expenses amortized over a weighted average period	1 year 1 month 20 days
Restricted stock awards rights vesting percentage	33.00%
Restricted stock awards rights vesting	1/36
Restricted stock awards granted	0	0	502,964
2018 Equity incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based payment Common stock shares authorised	4,913,665
Share based payment awards granted	4,279,693
Common stock available for future grant	0
2018 Equity incentive Plan [Member] | Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expiration period	4 years
Restricted stock awards rights vesting percentage	25.00%
Restricted stock awards rights vesting	1/48
2020 Incentive Award Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based payment awards granted	3,374,466
Common stock available for future grant	1,068,965
2020 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share based payment awards granted	0
Common stock available for future grant	368,901

Stock-based Compensation - Summ

Stock-based Compensation - Summary of Assumptions Used to Determine Grant-date Fair Value of Stock Options (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Expected dividend yield	0.00%
Stock Option [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Expected term (in years)	5 years 9 months 14 days	6 years 21 days
Risk-free interest rate	0.93%	1.94%
Expected dividend yield	0.00%	0.00%
Volatility	77.14%	60.24%

Stock-based Compensation - Su_2

Stock-based Compensation - Summary of Stock Options (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock Option [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Number of options - Beginning balance	346,872	1,062,457
Number of options, Granted	5,382,362	178,863
Number of options, Exercised	(188,990)	(891,229)
Number of options, Forfeited	(52,096)	(3,219)
Number of options - Ending balance	5,488,148	346,872	1,062,457
Number of options vested and expected to vest	5,427,891	884,623
Number of options vested and exercisable	464,567	31,330
Weighted average exercise price - Beginning balance	$ 1.30	$ 1.30
Weighted average exercise price Granted	11.42	1.30
Weighted average exercise price Exercised	2.33	1.30
Weighted average exercise price Forfeited	1.76	1.30
Weighted Average Exercise Price - Ending balance	11.19	1.30	$ 1.30
Weighted average exercise price Options vested and expected to vest	11.28	1.30
Weighted average exercise price options vested and exercisable	$ 3.20	$ 1.30
Weighted- Average Remaining Contractual Term, Outstanding	9 years 6 months 25 days	9 years 3 days	9 years 10 months 17 days
Weighted- Average Remaining Contractual Term, Options vested and expected to vest	9 years 6 months 29 days	9 years 3 days
Weighted- Average Remaining Contractual Term, Options vested and exercisable	8 years 11 months 12 days	8 years 10 months 17 days
Aggregate Intrinsic Value - Exercised	$ 810	$ 37
Aggregate Intrinsic Value - Options outstanding	90,335	744
Aggregate Intrinsic Value, options vested and expected to vest	88,881	1,896
Aggregate Intrinsic Value, Options vested and exercisable	$ 11,360	$ 67
Restricted Stock [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Number of awards - Beginning balance	827,187	1,521,387
Restricted stock awards granted	0	0	502,964
Number of awards, vested	(418,776)	(694,200)
Number of awards - Ending balance	408,411	827,187	1,521,387
Weighted average granted fair date value - Beginning balance	$ 1.01	$ 0.94
Weighted average granted fair date value, vested	0.86	0.86
Weighted average granted fair date value - Ending balance	$ 1.16	$ 1.01	$ 0.94
Aggregate Fair Value, Beginning balance	$ 834	$ 1,430
Aggregate Fair Value, vested	(361)	(596)
Aggregate Fair Value, Ending balance	$ 473	$ 834	$ 1,430

Stock-based Compensation - Su_3

Stock-based Compensation - Summary of Stock Based Compensation Expense Was Allocated (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated Share Based Compensation Expense	$ 2,975	$ 752
Research and Development [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated Share Based Compensation Expense	1,041	462
General and Administrative [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Allocated Share Based Compensation Expense	$ 1,934	$ 290

Fair value - Summary of Fair Va

Fair value - Summary of Fair Value of the Financial Instruments that are Measured at Fair Value on a Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 23, 2019	Dec. 31, 2018
Convertible preferred stock liability [Member]
Liabilities:
Convertible Preferred Stock Liability		$ (3,200)	$ (3,200)
Level 1 [Member]
Assets:
Cash and cash equivalents	$ 220,383	69,565
Fair value, assets	243,527
Liabilities:
Fair value, net asset (Liability)		127,712
Level 1 [Member] | Warrants [Member]
Liabilities:
Warrants		0
Level 1 [Member] | Convertible preferred stock liability [Member]
Liabilities:
Convertible Preferred Stock Liability		0
Level 2 [Member]
Assets:
Cash and cash equivalents	0	0
Fair value, assets	0
Liabilities:
Fair value, net asset (Liability)		0
Level 2 [Member] | Warrants [Member]
Liabilities:
Warrants		0
Level 2 [Member] | Convertible preferred stock liability [Member]
Liabilities:
Convertible Preferred Stock Liability		0
Level 3 [Member]
Assets:
Cash and cash equivalents	0	0
Fair value, assets	0
Liabilities:
Fair value, net asset (Liability)		(3,635)
Level 3 [Member] | Warrants [Member]
Liabilities:
Warrants	0	(461)		$ (861)
Level 3 [Member] | Convertible preferred stock liability [Member]
Liabilities:
Convertible Preferred Stock Liability	0	(3,174)		$ 0
U.S. Treasury bonds [Member] | Level 1 [Member]
Assets:
U.S. Treasury bonds	23,144	58,147
U.S. Treasury bonds [Member] | Level 2 [Member]
Assets:
U.S. Treasury bonds	0	0
U.S. Treasury bonds [Member] | Level 3 [Member]
Assets:
U.S. Treasury bonds	$ 0	$ 0

Fair value - Summary of Warrant

Fair value - Summary of Warrants Measured at Fair Value (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Warrants Were Measured at Fair Value [Line Items]
Dividend yield	0.00%
Warrant [Member]
Schedule Of Warrants Were Measured at Fair Value [Line Items]
Exercise price	$ 9.32	$ 9.32
Term (in years)	3 months 25 days
Risk-free interest rate	0.10%	1.63%
Dividend yield	0.00%	0.00%
Volatility	120.00%	75.00%
Warrant [Member] | Minimum [Member]
Schedule Of Warrants Were Measured at Fair Value [Line Items]
Term (in years)		2 years
Warrant [Member] | Maximum [Member]
Schedule Of Warrants Were Measured at Fair Value [Line Items]
Term (in years)		3 years

Fair value - Additional Informa

Fair value - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 23, 2019
Schedule Of Changes in Fair Value [Line Items]
Fair value of bifurcated conversion feature	$ 0	$ 0
Mandatorily Redeemable Preferred Stock [Member]
Schedule Of Changes in Fair Value [Line Items]
Redeemable convertible preferred stock liability at a fair value		$ 3,200	$ 3,200

Fair value - Summary of Changes

Fair value - Summary of Changes in Fair Value for Fair Value was Determined by Level 3 Inputs (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Changes in Fair Value [Line Items]
Change in fair value	$ 757	$ 51
Mandatorily Redeemable Preferred Stock [Member]
Schedule Of Changes in Fair Value [Line Items]
Beginning balance- Redeemable Convertible Preferred Stock Liability	3,200
Ending balance -Redeemable Convertible Preferred Stock Liability		3,200
Level 3 [Member] | Warrants [Member]
Schedule Of Changes in Fair Value [Line Items]
Beginning balance-Derivative Liabilities	461	861
Exercise of warrants	(137)	(52)
Change in fair value	296	(348)
Retirement of liability	(620)
Ending balance-Derivative Liabilities	0	461
Level 3 [Member] | Mandatorily Redeemable Preferred Stock [Member]
Schedule Of Changes in Fair Value [Line Items]
Beginning balance- Redeemable Convertible Preferred Stock Liability	3,174	0
Exercise of warrants	0	0
Change in fair value	11,386	3,174
Retirement of liability	(14,560)
Ending balance -Redeemable Convertible Preferred Stock Liability	$ 0	$ 3,174

Fair value - Summary of Redeema

Fair value - Summary of Redeemable Convertible Preferred Stock Liability Measured at Fair Value (Detail) - $ / shares	Oct. 06, 2020	Dec. 31, 2020	Dec. 31, 2019
Schedule of redeemable convertible preferred stock liability measured at fair value [Line Items]
Dividend yield		0.00%
Mandatorily Redeemable Preferred Stock [Member]
Schedule of redeemable convertible preferred stock liability measured at fair value [Line Items]
Exercise price	$ 11.21		$ 11.21
Term (in years)			1 year 3 months 7 days
Risk-free interest rate			1.55%
Dividend yield	0.00%		0.00%
Volatility			60.00%
Mandatorily Redeemable Preferred Stock [Member] | Minimum [Member]
Schedule of redeemable convertible preferred stock liability measured at fair value [Line Items]
Term (in years)	7 days
Risk-free interest rate	0.08%
Mandatorily Redeemable Preferred Stock [Member] | Maximum [Member]
Schedule of redeemable convertible preferred stock liability measured at fair value [Line Items]
Term (in years)	9 months
Risk-free interest rate	0.11%

License agreements and collab_2

License agreements and collaborations - Additional Information (Detail) - USD ($)	Jun. 25, 2020	Jun. 30, 2020	Apr. 30, 2020	Dec. 31, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 19, 2018	Aug. 16, 2018	Jun. 30, 2018
Expense related to milestone payments					$ 0	$ 0
KU Leuven [Member]
Collaboration expire period	2 years 6 months
Emory license agreement [Member] | Emory university [Member]
Non-refundable payment		$ 150,000
Long term purchase commitment additional obligation to be paid		35,000
Research plan funding amount		$ 270,000
Research plan expiry period		1 year
Long term purchase commitment period description					The research plan terminates one year from the effective date, with the Company having an option to extend for a second year
Expense related to milestone payments					$ 4,500,000	0
Payments for royalties					0	0
Emory license agreement [Member] | Emory university [Member] | Maximum [Member]
Aggregate payments									$ 125,000,000
Emory license agreement [Member] | Series A | Emory university [Member]
Debt instrument, conversion price								$ 9.32
Emory license agreement [Member] | Research and Development | Emory university [Member]
Upfront license fees paid					290,000
Convertible notes issued for purchasing license					600,000
Luxna license agreement [Member] | Luxna biotech Co Ltd [Member]
Expense related to milestone payments					0	0
Payments for royalties					$ 0	0
Luxna license agreement [Member] | Luxna biotech Co Ltd [Member] | Maximum [Member]
Aggregate payments							$ 55,500,000
Luxna license agreement [Member] | Research and Development | Luxna biotech Co Ltd [Member]
Upfront license fees paid				$ 600,000		$ 600,000
Non-refundable payment			$ 200,000
Katholieke Universiteit Leuven License Agreement [Member] | Katholieke Universiteit Leuven [Member]
Non-refundable payment	$ 30,000,000
Long term purchase commitment period description					Unless terminated earlier by either party, the agreement shall continue until the expiration of the last to expire royalty term, which is the later of the expiration or termination of the last valid patent claim covering the manufacture, use, sale or importation of the licensed product in a particular country or 10 years after the first commercial sale of a licensed product.
First commercial sale of a licensed product period	10 years
Katholieke Universiteit Leuven License Agreement [Member] | Katholieke Universiteit Leuven [Member] | Maximum [Member]
Non-refundable payment	$ 32,000,000
Merck License and Research Collaboration [Member] | Merck [Member]
Revenue recognized from collaborative arrangements					$ 0
Merck License and Research Collaboration [Member] | Merck [Member] | Maximum [Member]
Milestone payments and royalties receivable					$ 458,000,000

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Current Provision for Income Taxes (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Current:
State	$ 1,000	$ 1,000
Foreign	160,000	85,000
Total current provision for income taxes	161,000	86,000
Deferred:
Total deferred provision for income taxes	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	Jun. 29, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 27, 2020	Dec. 31, 2018
Income Tax Contingency [Line Items]
Deferred provision for income taxes		$ 0	$ 0
Increase in valuation allowance		$ 29,700,000
Deferred tax assets net operating loss carryforwards ownership change in percentage		50.00%
Offset percentage of taxable income		80.00%
Unrecognized tax benefits, income tax penalties and interest expense		$ 0	0
Unrecognized tax benefits		1,536,000	$ 637,000		$ 79,000
Effective income tax rate reconciliation, deduction, other		$ 0
Uncertain tax positions changes in period		12 months
Income tax examination, description		The Company is not currently under examination by income tax authorities in federal, state or other jurisdictions. All tax returns will remain open for examination by the federal and state authorities for three and four years, respectively, from the date of utilization of any NOLs or credits.
Impact of CARES Act to Income Taxes		$ 0
Suspension period	3 years
Cap period	3 years
Incentive tax credits offset amount of tax	$ 5,000,000
Taxable income	$ 1,000,000
CAA impact to tax provision				$ 0
Research and Development Credit [Member]
Income Tax Contingency [Line Items]
Unrecognized tax benefits		1,500,000
Federal [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards		$ 148,700,000
Deferred tax assets net operating loss carryforwards expiration year		2038
Deferred tax assets, research and development tax credit carryforwards		$ 4,100,000
Tax credit research and development carryforward expiration year		2038
Income tax examination, tax returns open for examination, period		3 years
State [Member]
Income Tax Contingency [Line Items]
Net operating loss carryforwards		$ 152,800,000
Deferred tax assets, research and development tax credit carryforwards		$ 2,100,000
Income tax examination, tax returns open for examination, period		4 years

Income Taxes - Schedule of Expe

Income Taxes - Schedule of Expected Income Tax (Benefit) Computed Using Federal Statutory Income Tax Rate to Company's Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Effective Income Tax Rate Continuing Operations Tax Rate Reconciliation [Abstract]
Income tax computed at federal statutory rate	21.00%	21.00%
State taxes, net of federal benefit	6.90%	8.18%
R&D credit carryovers	1.40%	1.87%
Change in valuation allowance	(27.24%)	(29.71%)
Permanent differences	(0.17%)	(1.32%)
Change in fair value of derivatives	(2.25%)
Other	0.21%	(0.18%)
Effective income tax rate	(0.15%)	(0.16%)

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets And Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Federal net operating loss carryforward	$ 31,233	$ 12,106
State net operating loss carryforward	10,664	4,227
Foreign net operating loss carryforward	33
Operating lease liabilities	4,453	3,776
Tax credits	4,639	1,865
Other accruals and reserves	1,558	675
Stock-based compensation	209
Other	10	7
Total deferred tax assets	52,799	22,656
Valuation allowance	(49,133)	(19,362)
Net deferred tax assets	3,666	3,294
Deferred tax liabilities:
Right of use assets	(2,857)	(2,067)
Stock-based compensation		(115)
Property and equipment	(809)	(1,112)
Total deferred tax liabilities	$ (3,666)	$ (3,294)

Income Taxes - Summary of Chang

Income Taxes - Summary of Changes to Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 637	$ 79
Increase related to prior year positions	131
Increase related to current year positions	768	558
Ending balance	$ 1,536	$ 637

Commitments and contingencies -

Commitments and contingencies - Additional Information (Detail) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies Disclosure [Abstract]
Contingent liabilities	$ 0	$ 0

Benefit plans - Additional Info

Benefit plans - Additional Information (Detail) - USD ($)	6 Months Ended		12 Months Ended
	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, matching amount				$ 432,000	$ 274,000
Defined contribution plan, matching percentage				1.75%
Regular Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Underfunded amount recognized in accrued liabilities	$ 261,000			$ 261,000	90,000
Actuarial gain (loss) recognized in accumulated other comprehensive (loss) income				(84,000)	(85,000)
Defined benefit plan accumulated benefit obligation	$ 900,000			$ 900,000	$ 600,000
Expected long-term rate of return on plan assets net of guaranteed return from insurance company holding investments	0.50%	0.75%
Defined benefit plan guaranteed return from insurance company holding investments	0.10%	0.10%
Expected long-term rate of return on assets	0.40%	0.65%		0.53%	0.65%
Company contributions				$ 186,000	$ 182,000
Actuarial gain (loss) recognized in accumulated other comprehensive (loss) income				$ (82,000)	$ (86,000)
Regular Pension Plan [Member] | Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Company contributions			$ 297,000
Regular Pension Plan [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fixed income investments maturity				12 years	12 years
Top Hat Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Underfunded amount recognized in accrued liabilities	$ 1,100,000			$ 1,100,000	$ 412,000
Defined benefit plan accumulated benefit obligation	$ 1,700,000			$ 1,700,000	$ 600,000
Expected long-term rate of return on plan assets net of guaranteed return from insurance company holding investments				0.00%
Defined benefit plan guaranteed return from insurance company holding investments				0.00%
Expected long-term rate of return on assets				0.00%	0.00%
Company contributions				$ 496,000	$ 281,000
Defined benefit plan legal yield guarantee percent					1.75%
Actuarial gain (loss) recognized in accumulated other comprehensive (loss) income				$ (52,000)	$ (32,000)
Top Hat Plan [Member] | Forecast [Member]
Defined Benefit Plan Disclosure [Line Items]
Company contributions			$ 600,000
Top Hat Plan [Member] | Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Fixed income investments maturity				12 years	12 years

Benefit plans - Summary of Net

Benefit plans - Summary of Net Periodic Benefit Costs and Other Amounts Recognized in Other Comprehensive Loss (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Regular Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 186,000	$ 94,000
Expected return on plan assets	(4,000)	(2,000)
Interest costs	5,000	6,000
Amortization of actuarial gains/(losses)	2,000
Other costs	46,000	29,000
Prior service costs	33,000	58,000
Net periodic benefit costs	268,000	185,000
Net actuarial loss (gain) in plan asset and projected benefit obligation recognized in other comprehensive loss	82,000	86,000
Total recognized	350,000	271,000
Top Hat Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Interest costs	8,000	5,000
Other costs	114,000	27,000
Prior service costs	794,000	348,000
Net periodic benefit costs	916,000	380,000
Net actuarial loss (gain) in plan asset and projected benefit obligation recognized in other comprehensive loss	52,000	32,000
Total recognized	$ 968,000	$ 412,000

Benefit plans - Summary of Acti

Benefit plans - Summary of Activities Under Pension Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Regular Pension Plan [Member]
Change in benefit obligation:
Benefit obligation, beginning of year	$ 560	$ 317
Service cost	186	94
Interest costs	5	6
Prior service cost	62	58
Actuarial loss (gain)	84	85
Benefit obligation, end of year	897	560
Change in plan assets:
Fair value of plan assets, beginning of year	470	317
Company contributions	186	182
Expected net return on plan assets	4	2
Other costs	(23)	(30)
Actuarial loss	(1)	(1)
Fair value of plan assets, end of year	636	470
Funded status	(261)	(90)
Top Hat Plan [Member]
Change in benefit obligation:
Benefit obligation, beginning of year	649	261
Interest costs	8	5
Prior service cost	834	348
Actuarial loss (gain)	58	35
Benefit obligation, end of year	1,729	649
Internal transfer	180
Change in plan assets:
Fair value of plan assets, beginning of year	237	(20)
Company contributions	496	281
Other costs	(100)	(27)
Fair value of plan assets, end of year	629	237
Internal transfer	(10)
Actual return on plan assets	6	3
Funded status	$ (1,100)	$ (412)

Benefit plans - Summary of Weig

Benefit plans - Summary of Weighted-average Rates used to Determine Net Periodic Benefit Costs and Projected Benefit Obligations (Detail)	6 Months Ended		12 Months Ended
	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019
Regular Pension Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Discount rate			0.40%	0.90%
Rate of increased salary levels			1.80%	1.80%
Expected long-term rate of return on assets	0.40%	0.65%	0.53%	0.65%
Top Hat Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Discount rate			0.40%	1.90%
Rate of increased salary levels			1.80%	1.80%
Expected long-term rate of return on assets			0.00%	0.00%

Benefit plans - Summary of Fair

Benefit plans - Summary of Fair Values of Pension Plan Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Regular Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	$ 636	$ 470	$ 317
Regular Pension Plan [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	636	470
Regular Pension Plan [Member] | Level 3 [Member] | Insurance Policies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	706	485
Regular Pension Plan [Member] | Level 3 [Member] | Current Account With Insurer [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	(70)	(15)
Top Hat Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	629	237	$ (20)
Top Hat Plan [Member] | Level 3 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	629	237
Top Hat Plan [Member] | Level 3 [Member] | Sundry Liabilities [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	(797)	(27)
Top Hat Plan [Member] | Level 3 [Member] | Insurance Policies [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair values of plan assets	$ 1,426	$ 264

Benefit plans - Summary of Chan

Benefit plans - Summary of Changes in Fair Value of Regular Pension Plan Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Regular Pension Plan [Member] | Level 3 [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Unobservable inputs - beginning	$ 470	$ 317
Actual return on plan assets	3	1
Net purchases, sales and settlements	186	182
Transfers out of Level 3 assets	(23)	(30)
Unobservable inputs - ending	636	470
Top Hat Plan [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Actual return on plan assets	6	3
Top Hat Plan [Member] | Level 3 [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Unobservable inputs - beginning	237	(20)
Actual return on plan assets	6	3
Net purchases, sales and settlements	496	281
Transfers out of Level 3 assets	(110)	(27)
Unobservable inputs - ending	$ 629	$ 237

Benefit plans - Summary of Esti

Benefit plans - Summary of Estimated Future Benefit Payments (Detail) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Regular Pension Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
2021	$ 6
2022	4
2023	4
2024	3
2025	3
2026−2030	23
Estimated future benefit payments	43
Top Hat Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
2021	4	$ 2
2022	4	2
2023	4	2
2024	4	2
2025	5	2
2026−2030	39	10
Estimated future benefit payments	$ 60	$ 20

Net loss per share - Schedule o

Net loss per share - Schedule of Earnings Per Share Basic and Diluted (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Earnings Per Share Basic And Diluted [Abstract]
Net loss	$ (108,543)	$ (52,264)
Weighted average common stock outstanding, basic and diluted	9,988,191	2,007,173
Net loss per share – basic and diluted	$ (10.87)	$ (26.04)

Net loss per share - Schedule_2

Net loss per share - Schedule of Antidilutive Securities Excluded From Computation of Earnings Per Share (Detail) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	3,753,161	24,566,018
Convertible preferred stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount		19,163,877
Forward contract to issue convertible preferred stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount		3,569,630
Options to purchase common stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	3,344,765	884,623
Unvested restricted stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	408,396	827,187
Warrants to purchase preferred stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount		120,701