Sensei Biotherapeutics (SNSE) 10-Q 13 May 21 2021 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2021	May 07, 2021
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Registrant Name	Sensei Biotherapeutics, Inc.
Entity Central Index Key	0001829802
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		30,588,495
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, $0.0001 par value per share
Trading Symbol	SNSE
Security Exchange Name	NASDAQ
Entity File Number	001-39980
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	83-1863385
Entity Address, Address Line One	1405 Research Blvd
Entity Address, Address Line Two	Suite 125
Entity Address, City or Town	Rockville
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20850
City Area Code	240
Local Phone Number	243-8000
Document Quarterly Report	true
Document Transition Report	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 169,418	$ 16,596
Deferred offering costs		2,105
Prepaid expenses	3,307	1,375
Other current assets	60
Total current assets	172,785	20,076
Property and equipment, net	1,655	1,266
Deposits	36	86
Total assets	174,476	21,428
Current liabilities:
Accounts payable and accrued liabilities	2,002	3,882
Other liabilities	473	948
Total current liabilities	2,475	4,830
Debt	567	567
Other non-current liabilities	182	138
Total liabilities	3,224	5,535
Commitments and contingencies (Note 7)
Stockholders’ equity (deficit):
Common stock, $0.0001 par value; 1,230,000,000 shares authorized as of March 31, 2021, 30,588,495 shares and 1,875,422 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	3
Additional paid-in capital	291,633	55,969
Accumulated deficit	(120,384)	(112,412)
Total stockholders’ equity (deficit)	171,252	(56,443)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 174,476	21,428
Convertible Preferred Stock Series AA
Temporary Equity
Convertible preferred stock		61,411
Convertible Preferred Stock Series BB
Temporary Equity
Convertible preferred stock		$ 10,925

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	1,230,000,000	1,230,000,000
Common stock, shares issued	30,588,495	1,875,422
Common stock, shares outstanding	30,588,495	1,875,422

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating expenses:
Research and development	$ 3,365	$ 2,195
General and administrative	4,604	1,908
Total operating expenses	7,969	4,103
Loss from operations	(7,969)	(4,103)
Other expense:
Interest expense, including $0 and $645 with related parties in the three months ended March 31, 2021 and 2020, respectively	(3)	(1,629)
Fair value adjustments on embedded debt derivatives, including $0 and $575 with related parties in the three months ended March 31, 2021 and 2020, respectively		995
Gain on debt extinguishment		45
Net loss	(7,972)	(4,692)
Cumulative dividends on convertible preferred stock		(104)
Net loss attributable to common stockholders	$ (7,972)	$ (4,796)
Net loss per common share, basic and diluted	$ (0.42)	$ (4)
Weighted-average number of shares used in computing net loss per common share, basic and diluted	18,904,853	1,199,550

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Interest expense, related party	$ 0	$ 645
Fair value adjustments on embedded debt derivative with related parties	$ 0	$ 575

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF CONVERTIBLE PREFERRED STOCK, COMMON STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Unaudited) - USD ($) $ in Thousands	Total	Convertible Preferred Stock (Series A-F)	Convertible Preferred Stock Series AA	Convertible Preferred Stock Series BB	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Beginning balance at Dec. 31, 2019	$ (68,662)					$ 23,650	$ (92,312)
Temporary equity, Beginning balance, shares at Dec. 31, 2019		15,257,663
Temporary equity, Beginning balance at Dec. 31, 2019		$ 47,545
Beginning balance, shares at Dec. 31, 2019					369,491
Stock-based compensation expense	194					194
Conversion of preferred stock into common stock	47,545					47,545
Temporary equity, Conversion of preferred stock into common stock, shares		(15,257,663)
Temporary equity, Conversion of preferred stock into common stock		$ (47,545)
Conversion of preferred stock into common stock, shares					627,871
Conversion of common stock into series AA preferred stock	(17,274)					(17,274)
Temporary equity, Conversion of common stock into series AA preferred stock			210,310,025
Temporary equity, Conversion of common stock into series AA preferred stock, shares			$ 17,274
Conversion of common stock into series AA preferred stock, shares					(148,732)
Preferred stock issued in exchange for note redemption			$ 15,456
Preferred stock issued in exchange for note redemption, shares			188,173,050
Issuance of preferred stock			$ 10,567
Issuance of preferred stock, shares			128,655,262
Exercise of common stock warrants, shares					634,118
Net loss	(4,692)						(4,692)
Ending balance at Mar. 31, 2020	(42,889)					54,115	(97,004)
Temporary equity, Ending balance, shares at Mar. 31, 2020			527,138,337
Temporary equity, Ending balance at Mar. 31, 2020			$ 43,297
Ending balance, shares at Mar. 31, 2020					1,482,748
Beginning balance at Dec. 31, 2020	(56,443)					55,969	(112,412)
Temporary equity, Beginning balance, shares at Dec. 31, 2020			747,683,172	52,680,306
Temporary equity, Beginning balance at Dec. 31, 2020			$ 61,411	$ 10,925
Beginning balance, shares at Dec. 31, 2020					1,875,422
Stock-based compensation expense	1,349					1,349
Conversion of preferred stock into common stock	95,828				$ 2	95,826
Temporary equity, Conversion of preferred stock into common stock, shares			(747,683,172)	(165,956,208)
Temporary equity, Conversion of preferred stock into common stock			$ (61,411)	$ (34,416)
Conversion of preferred stock into common stock, shares					19,034,069
Issuance of preferred stock				$ 23,491
Issuance of preferred stock, shares				113,275,902
Issuance of common stock upon closing of the initial public offering, net of issuance costs	138,489				$ 1	138,488
Issuance of common stock upon closing of the initial public offering, net of issuance costs, shares					8,030,295
Exercise of common stock warrants	1					1
Exercise of common stock warrants, shares					1,648,709
Net loss	(7,972)						(7,972)
Ending balance at Mar. 31, 2021	$ 171,252				$ 3	$ 291,633	$ (120,384)
Ending balance, shares at Mar. 31, 2021					30,588,495

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating activities
Net loss	$ (7,972)	$ (4,692)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,349	194
Depreciation and amortization	98	23
Accretion on debt		1,578
Fair value adjustments on embedded debt derivatives		(995)
Interest on capital lease	3	3
Gain on debt extinguishment		(45)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,992)	(834)
Deposits	50	(36)
Accounts payable and accrued liabilities	(1,880)	(1,104)
Accrued interest		50
Other liabilities	(423)	(602)
Net cash used in operating activities	(10,767)	(6,460)
Investing activities
Purchases of property and equipment	(487)	(52)
Net cash used in investing activities	(487)	(52)
Financing activities
Proceeds from the exercise of common stock warrants and options	1
Capital lease payments	(10)	(10)
Proceeds from issuance of common stock upon initial public offering, net of issuance costs	140,594
Net cash provided by financing activities	164,076	10,557
Net increase in cash and cash equivalents	152,822	4,045
Cash and cash equivalents at beginning of period	16,596	251
Cash and cash equivalents at end of period	169,418	4,296
Supplemental disclosure of noncash financing and investing information:
Property and equipment additions included in accounts payable and accrued liabilities	15	5
Issuance costs included in accounts payable and accrued liabilities	534
Interest on financing	3	3
Convertible preferred stock issued in exchange for note redemption		15,456
Conversion of Series A, B, C, D, E, F Convertible Preferred Stock into Common Stock
Supplemental disclosure of noncash financing and investing information:
Conversion of stock		47,545
Conversion of Series AA and BB Convertible Preferred Stock into Common Stock
Supplemental disclosure of noncash financing and investing information:
Conversion of stock	95,828
Conversion of Common Stock into Series AA Convertible Preferred Stock
Supplemental disclosure of noncash financing and investing information:
Conversion of stock		17,274
Series AA Convertible Preferred Stock
Financing activities
Proceeds on the issuance of convertible preferred stock		$ 10,567
Series BB Convertible Preferred Stock
Financing activities
Proceeds on the issuance of convertible preferred stock	$ 23,491

Organization and Operations

Organization and Operations	3 Months Ended
	Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
ORGANIZATION AND OPERATIONS	1. ORGANIZATION AND OPERATIONS Business Sensei Biotherapeutics, Inc. (the “Company” or “Sensei”) is a clinical-stage immunotherapy company that was incorporated in 1999 as a Maryland corporation until incorporated in Delaware on December 1, 2017. The Company is engaged in the discovery and development of next generation therapies with an initial focus on treatments for cancer. Liquidity and capital resources Since its inception, the Company has devoted substantially all of its resources to advancing development of its portfolio of programs, establishing and protecting its intellectual property, conducting research and development activities, organizing and staffing the Company, business planning, raising capital and providing general and administrative support for these operations. The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry including, but not limited to, technical risks associated with the successful research, development and manufacturing of product candidates, development by competitors of new technological innovations, dependence on key personnel, protection of proprietary technology, compliance with government regulations and the ability to secure additional capital to fund operations. Current and future programs will require significant research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure. Even if the Company’s drug development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. Since its inception, the Company has incurred substantial losses and had a net loss of $8.0 million for the three months ended March 31, 2021. As of March 31, 2021, the Company had an accumulated deficit of $120.4 million. The Company expects to generate operating losses and negative operating cash flows for the foreseeable future. In February 2021, the Company completed its initial public offering (“IPO”), in which the Company issued and sold 8,030,295 shares of its common stock at a public offering price of $19.00 per share, for aggregate gross proceeds of $152.6 million. The Company received $138.5 million in net proceeds after deducting underwriting discounts and estimated offering expenses payable by the Company. The Company expects that its cash and cash equivalents as of March 31, 2021 of $169.4 million will be sufficient to fund its operations for at least the next twelve months from the date of issuance of these financial statements. The Company will need additional financing to support its continuing operations and pursue its growth strategy. Until such time as the Company can generate significant revenue from product sales, if ever, it expects to finance its operations through a combination of equity offerings, debt financings, collaborations, strategic alliances and licensing arrangements. The Company may be unable to raise additional funds or enter into such other agreements when needed on favorable terms or at all. The inability to raise capital as and when needed would have a negative impact on the Company’s financial condition and its ability to pursue its business strategy. The Company will need to generate significant revenue to achieve profitability, and it may never do so. Reverse stock split On January 29, 2021, the Company effected a reverse stock split of the Company’s common stock on a 48-for-1 basis (the “Reverse Stock Split”). In connection with the Reverse Stock Split, the conversion ratio for the Company’s Series AA and Series BB convertible preferred stock was proportionately adjusted such that the common stock issuable upon conversion of such preferred stock was decreased in proportion to the Reverse Stock Split. Accordingly, all common stock share and per share amounts, as well as all preferred stock conversion ratios, for all periods presented in these financial statements have been retroactively adjusted, to reflect this reverse stock split and adjustment of the Series AA and BB convertible preferred stock conversion ratios.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Principles of Consolidation The Company has prepared the accompanying condensed consolidated financial statements in conformity with generally accepted accounting principles in the United States (“US GAAP”). The condensed consolidated financial statements include those accounts of the Company and its subsidiaries after elimination of all intercompany accounts and transactions. Unaudited interim financial information The condensed consolidated financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and note disclosures normally included in financial statements prepared in accordance with US GAAP have been condensed or omitted from these Use of Estimates The preparation of condensed consolidated financial statements in conformity with US GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the reported amounts of expenses during the reporting periods presented. Estimates are used for, but are not limited to, depreciation of equipment, the Company’s enterprise value, fair value of financial instruments, the Company’s ability to continue as a going concern and contingencies. Actual results may differ from those estimates. Recently Issued Accounting Standards Updates In February 2016, the FASB issued Accounting Standards Updates (“ASU”) No. 2016-02, Leases (Topic 842) In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement Topic 820 In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes

Property and Equipment, Net

Property and Equipment, Net	3 Months Ended
	Mar. 31, 2021
Property Plant And Equipment [Abstract]
PROPERTY AND EQUIPMENT, NET	3. PROPERTY AND EQUIPMENT, NET Property and equipment, net consist of the following (in thousands): March 31, 2021 December 31, 2020 Office equipment and furniture $ 121 $ 94 Research equipment 2,227 1,767 Total property and equipment 2,348 1,861 Less accumulated depreciation and amortization (693 ) (595 ) Property and equipment, net $ 1,655 $ 1,266 Depreciation and amortization expense for the three months ended March 31, 2021 and 2020 was $98 thousand and $23 thousand, respectively.

Other Current Liabilities

Other Current Liabilities	3 Months Ended
	Mar. 31, 2021
Other Liabilities Disclosure [Abstract]
OTHER CURRENT LIABILITIES	4. Other current liabilities Other current liabilities consist of the following (in thousands): March 31, 2021 December 31, 2020 Compensation and benefits $ 440 $ 916 Other 33 32 Total other current liabilities $ 473 $ 948

Debt

Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
DEBT	5. Debt In May 2020, the Company received $567 thousand in loan funding from the Paycheck Protection Program (“PPP”) pursuant to the Coronavirus Aid, Relief, and Economic Security Act, as amended by the Flexibility Act, and administered by the Small Business Administration. The unsecured loan (the “PPP Loan”) is with Silicon Valley Bank. Under the terms of the PPP Loan, interest accrues on the outstanding principal at a rate of 1.0% per annum. To the extent the PPP Loan amount is not forgiven under the PPP Loan, the Company is obligated to make equal monthly payments of principal and interest, beginning after determination of forgiveness by the lender. If the Company applies for forgiveness before August 2021 and forgiveness is not granted, principal and interest payments will be required beginning in May 2022. If the Company does not apply for loan forgiveness by August 2021, principal and interest will be required beginning in August 2021.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	6. FAIR VALUE MEASUREMENTS The Company did not have any financial liabilities measured at fair value on a recurring basis as of March 31, 2021 and December 31, 2020. The Company’s embedded debt derivatives during 2020 are measured at fair value using a probability-weighted discounted cash flow valuation methodology. The determination of the fair value of embedded debt derivatives includes inputs not observable in the market and as such, represents a Level 3 measurement. The methodology utilized requires inputs based on certain subjective assumptions, including probabilities of debt settlement scenarios and a discount rate. This approach results in the classification of these embedded debt derivatives as Level 3 of the fair value hierarchy. The assumptions utilized to value the embedded debt derivatives during the three months ended March 31, 2020 prior to the settlement of such instruments included the actual outcome of the underling debt host contract, whether it was settled on a qualified financing prior to the contractual maturity date or settlement at the contractual maturity date. For the three months ended March 31, 2020, the Company recognized $1.0 million of income in the condensed consolidated statement of operations as other income—fair value adjustments on embedded debt derivatives. The following table provides a reconciliation of embedded debt derivatives measured at fair value on a recurring basis using significant unobservable inputs (Level 3) (in thousands): Amount Balance at December 31, 2019 $ 3,920 Change in fair value (995 ) Settlement (2,925 ) Balance at March 31, 2020 $ — There were no transfers among Level 1, Level 2 or Level 3 categories in the three months ended March 31, 2020.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	7. COMMITMENTS AND CONTINGENCIES Operating Lease As of March 31, 2021, the Company leases office facilities and other equipment under operating leases, which expire at various dates through 2027. Lease expense for the three months ended March 31, 2021 and 2020 was $234 thousand and $304 thousand, respectively. The following table presents the future annual minimum payments required under noncancellable operating leases at March 31, 2021 (in thousands): Remainder of 2021 $ 796 2022 1,192 2023 1,201 2024 1,223 2025 1,259 2026 657 2027 59 Total operating lease obligations $ 6,387 As agreements Capital Lease The Company leases research equipment under a capital finance lease. The capital lease asset is classified within property and equipment, net within the Company’s condensed consolidated balance sheets. The following table presents the future annual minimum payments under the capitalized lease, together with the present value of net minimum lease payments at March 31, 2021 (in thousands): Remainder of 2021 $ 31 2022 41 2023 41 2024 14 Total capital lease obligations 127 Less amount representing interest (16 ) Present value of minimum capital lease obligations $ 111 License Agreements In the normal course of business, the Company enters into licensing agreements with various parties to obtain the right to make, use, and sell licensed products currently in development. Litigation The Company records estimated losses from loss contingencies, such as a loss arising from a litigation, when it determines that it is probable a liability has been incurred and the amount of loss can be reasonably estimated. Litigation is subject to many factors that are difficult to predict so that there can be no assurance, in the event of a material unfavorable result in one or more claims, the Company will not incur material costs. During 2017, the Company became actively involved in a matter pending in the Ontario (Canada) Superior Court of Justice which names, among multiple other defendants, the Company and two former officers of the Company. The claims pending in this matter allege breach of contract by the Company and seek declaratory and other relief, including monetary damages from the Company, and the individual defendants, including the Company’s former officers. The claims by such plaintiffs were originally made in a lawsuit filed in Ontario during October 2011, but was not pursued by such plaintiffs in any material manner until 2017. The Company believes that there is no merit to the claims alleged against the Company and its former officers, including no alleged breach of contract by the Company, and intends to vigorously defend against the claims pertaining to the Company and its former officers. At the present stage of the suit, management believes the outcome in this matter is not likely to have any material impact on the Company’s results, cash flows, or financial position. Coronavirus pandemic On January 30, 2020, the World Health Organization (“WHO”) announced a global health emergency because of a new strain of coronavirus originating in Wuhan, China (the “COVID-19 outbreak”) and the risks to the international community as the virus spreads globally beyond its point of origin. In March 2020, the WHO classified the COVID-19 outbreak as a pandemic, based on the rapid increase in exposure globally. The full impact of the COVID-19 outbreak continues to evolve as of the date of these financial statements. As such, it is uncertain as to the full magnitude that the pandemic will have on the Company’s financial condition, liquidity, and future results of operations. Management is actively monitoring the global situation on its financial condition, liquidity, operations, suppliers, industry, and workforce. Given the daily evolution of the COVID-19 outbreak and the global responses to curb its spread, the Company is not able to estimate the effects of the COVID-19 outbreak on its results of operations, financial condition, or liquidity. Although the Company cannot estimate the length or gravity of the impact of the COVID-19 outbreak at this time, if the pandemic continues, it may have a material adverse effect on the Company’s results of future operations, financial position, and liquidity in 2021.

Equity

Equity	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
EQUITY	8. Equity Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are not entitled to receive dividends, unless declared by the board of directors. Series BB Convertible Preferred Stock Issuance In January 2021, the Company issued and sold 113,275,902 shares of Series BB convertible preferred stock at $0.207383 per share in exchange for $23.5 million in gross proceeds. Initial Public Offering In February 2021, the Company completed its IPO in which the Company issued and sold 8,030,295 shares of its common stock, including 1,030,243 shares pursuant to the partial exercise of the underwriters’ option to purchase additional shares, at a public offering price of $19.00 per share, for aggregate gross proceeds of $152.6 million. The Company received approximately $138.5 million in net proceeds after deducting underwriting discounts and estimated offering expenses payable by the Company. Upon closing of the IPO on February 8, 2021, all of the Company’s outstanding preferred stock converted into an aggregate of 19,034,069 shares of common stock. On February 8, 2021, in connection with the IPO, the Company filed an Amended and Restated Certificate of Incorporation (the Common Stock Warrants The following is a summary of the common stock warrant activity related to common stock warrants issued in conjunction with equity and debt fundraising events for the three months ended March 31, 2021: Number of Common Stock Warrants Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2020 412,262 $ 9.60 6.71 $ 1,380 Granted 1,648,709 $ 0.01 Exercised (1,648,709 ) $ (0.01 ) Expired — $ — Outstanding at March 31, 2021 412,262 $ 9.60 6.47 $ 4,122

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
STOCK-BASED COMPENSATION	9. STOCK-BASED COMPENSATION 2018 Equity Incentive Plan The Company’s 2018 Stock Incentive Plan (the “2018 Plan”), provided for the Company to grant qualified incentive options, nonqualified options, stock grants and other stock-based awards to employees and non-employees to purchase the Company’s common stock. Upon the effectiveness of the 2021 Plan (as defined below), no further issuances will be made under the 2018 Plan. 2021 Stock Option and Incentive Plan The 2021 Equity Incentive Plan (the “2021 Plan”) was approved by the board of directors on January 27, 2021, and the Company’s stockholders on January 28, 2021 and became effective on the execution of the underwriting agreement related to the IPO. The 2021 Plan provides for the grant of incentive stock options to employees, including employees of any parent or subsidiary corporations, and for the grant of nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance awards and other forms of stock awards to employees, directors, and consultants, including employees and consultants of the Company’s affiliates. The number of shares initially reserved for issuance under the 2021 Plan was 5,000,000, which will automatically increase on January 1 of each calendar year, starting on January 1, 2022 through January 1, 2031, in an amount equal to 4.0% of the total number of shares of the Company’s capital stock outstanding on the last day of the calendar month before the date of each automatic increase, or a lesser number of shares determined by the board of directors. 2021 Employee Stock Purchase Plan The 2021 Employee Stock Purchase Plan (the “2021 ESPP”) was approved by the Company’s board of directors on January 27, 2021 Stock Options During 2021, the Company granted options to purchase shares of common stock to employees, consultants, and nonexecutive directors pursuant to the 2018 Plan and 2021 Plan, respectively. The Company uses the Black-Scholes option-pricing model to estimate the fair value of the stock options on the grant dates at a weighted average fair value of $13.84. The following is a summary of the stock option award activity during the three months ended March 31, 2021: Number of Stock Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2020 1,947,123 $ 5.70 9.56 $ 10,284 Granted 1,253,825 $ 18.06 Exercised — $ — Forfeited (43,749 ) $ (6.00 ) Expired — $ — Outstanding at March 31, 2021 3,157,199 $ 10.60 9.50 $ 23,557 Exercisable at March 31, 2021 446,771 $ 15.70 9.04 $ 5,096 Options expected to vest as of March 31, 2021 2,710,428 $ 9.76 9.62 $ 18,461 The total fair value of options vested during the three months ended March 31, 2021 was $1.1 million. At March 31, 2021, there was approximately $21.4 million of unrecognized stock-based compensation expense associated with the stock options, which is expected to be recognized over a weighted-average period of 3.55 years. Common Stock Warrants The following is a summary of the employee-issued common stock warrant activity during the three months ended March 31, 2021 Number of Common Stock Warrants Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2020 57,212 $ 7.62 3.64 $ 98 Granted — $ — Exercised — $ — Expired — $ — Outstanding and exercisable at March 31, 2021 57,212 $ 7.62 3.39 $ 495 As of March 31, 2021 there was no unrecognized stock-based compensation expense associated with the common stock warrants. For the three months ended March 31, 2021 and 2020, the Company utilized the Black-Scholes option-pricing model for estimating the fair value of the stock options and common stock warrants granted. The following table presents the assumptions and the Company’s methodology for developing each of the assumptions used: Three Months Ended March 31, 2021 Volatility 91.5%-98.04% Expected life (years) 5.52-6.08 Risk-free interest rate 0.5%–1.0% Dividend rate —% • Volatility—The Company estimates the expected volatility of its common stock at the date of grant based on the historical volatility of comparable public companies over the expected term. • Expected life—The expected life is estimated as the contractual term. • Risk-free interest rate—The risk-free rate for periods within the estimated life of the stock award is based on the U.S. Treasury yield curve in effect at the time of grant. • Dividend rate—The assumed dividend yield is based upon the Company’s expectation of not paying dividends in the foreseeable future. Stock-based compensation expense was recorded in the following line items in the condensed consolidated statements of operations for the three months ended March 31, 2021 and 2020 (in thousands): Three Months Ended March 31, 2021 2020 Research and development $ 509 $ 51 General and administrative 840 143 Total stock-based compensation expense $ 1,349 $ 194

Employee Retirement Plan

Employee Retirement Plan	3 Months Ended
	Mar. 31, 2021
Compensation And Retirement Disclosure [Abstract]
EMPLOYEE RETIREMENT PLAN	10. EMPLOYEE RETIREMENT PLAN The Company maintains a defined contribution 401(k) profit-sharing plan (the “Plan”) for all employees. Under the Plan, participants may make voluntary contributions up to the maximum amount allowable by law. The Plan is based on employees’ salary deferral, and the Company matches employees’ contributions up to 4% of the employees’ base salary. Employees are 100% vested in the Company’s match contributions. During the three months ended March 31, 2021 and 2020, the Company accrued expense of $29 thousand and $26 thousand, respectively

Related-Party Transactions

Related-Party Transactions	3 Months Ended
	Mar. 31, 2021
Related Party Transactions [Abstract]
RELATED-PARTY TRANSACTIONS	11. RELATED-PARTY TRANSACTIONS Debt During March 2020, a principal owner of the Company purchased the 2019 Special Note directly from the original holder. Consulting Agreement During 2020, the Company entered into an agreement with a principal owner of the Company to provide consulting services to the Company in exchange for $1,500 thousand. Under the terms of the agreement, the Company recorded expense of $1,125 thousand in 2020, with payment made in January 2021. The contract was completed and the remaining balance of $375 thousand under the agreement was recorded as an expense in January 2021.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
INCOME TAXES	12. INCOME TAXES The Company recorded no provision for income taxes for the three months ended March 31, 2021 and 2020. Deferred tax assets and deferred tax liabilities are recognized based on temporary differences between the financial reporting and tax bases of assets and liabilities using statutory rates. Management of the Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets, which are comprised principally of net operating loss carryforwards and research and development credits. Under the applicable accounting standards, management has considered the Company’s history of losses and concluded that it is more likely than not that the Company will not recognize the benefits of federal and state deferred tax assets. Accordingly, a full valuation allowance has been established against the Company’s otherwise recognizable net deferred tax assets.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
NET LOSS PER SHARE	13. NET LOSS PER SHARE Basic and diluted net loss per share attributable to common stockholders is calculated as follows (in thousands except share and per share amounts): Three Months Ended March 31, 2021 2020 Net loss $ (7,972 ) $ (4,692 ) Cumulative dividends on convertible preferred stock — (104 ) Net loss attributable to common stockholders $ (7,972 ) $ (4,796 ) Net loss per share—basic and diluted $ (0.42 ) $ (4.00 ) Weighted-average number of shares used in computing net loss per share—basic and diluted 18,904,853 1,199,550 The following outstanding potentially dilutive securities have been excluded from the calculation of diluted net loss per share, as their effect is anti-dilutive: Three Months Ended March 31, 2021 2020 Convertible preferred stock — 527,138,337 Stock options to purchase common stock 3,157,199 1,947,123 Warrants issued to employees and contractor to purchase common stock 57,212 57,420 Warrants issued related to convertible notes and other equity agreements 412,262 22,937

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	14. SUBSEQUENT EVENTS Subsequent events have been evaluated through the date of filing of the unaudited condensed financial statements. The Company has concluded that no subsequent events have occurred that require disclosure.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The Company has prepared the accompanying condensed consolidated financial statements in conformity with generally accepted accounting principles in the United States (“US GAAP”). The condensed consolidated financial statements include those accounts of the Company and its subsidiaries after elimination of all intercompany accounts and transactions.
Unaudited interim financial information	Unaudited interim financial information The condensed consolidated financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and note disclosures normally included in financial statements prepared in accordance with US GAAP have been condensed or omitted from these
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with US GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements, and the reported amounts of expenses during the reporting periods presented. Estimates are used for, but are not limited to, depreciation of equipment, the Company’s enterprise value, fair value of financial instruments, the Company’s ability to continue as a going concern and contingencies. Actual results may differ from those estimates.
Recently Issued Accounting Standards Updates	Recently Issued Accounting Standards Updates In February 2016, the FASB issued Accounting Standards Updates (“ASU”) No. 2016-02, Leases (Topic 842) In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement Topic 820 In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	3 Months Ended
	Mar. 31, 2021
Property Plant And Equipment [Abstract]
Summary of Property and Equipment, Net	Property and equipment, net consist of the following (in thousands): March 31, 2021 December 31, 2020 Office equipment and furniture $ 121 $ 94 Research equipment 2,227 1,767 Total property and equipment 2,348 1,861 Less accumulated depreciation and amortization (693 ) (595 ) Property and equipment, net $ 1,655 $ 1,266

Other Current Liabilities (Tabl

Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 2021
Other Liabilities Disclosure [Abstract]
Summary of Other Current Liabilities	Other current liabilities consist of the following (in thousands): March 31, 2021 December 31, 2020 Compensation and benefits $ 440 $ 916 Other 33 32 Total other current liabilities $ 473 $ 948

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Schedule of Reconciliation of Embedded Debt Derivatives Measured Fair Value on Recurring Basis	The following table provides a reconciliation of embedded debt derivatives measured at fair value on a recurring basis using significant unobservable inputs (Level 3) (in thousands): Amount Balance at December 31, 2019 $ 3,920 Change in fair value (995 ) Settlement (2,925 ) Balance at March 31, 2020 $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Annual Minimum Payments Under Noncancellable Operating Lease	The following table presents the future annual minimum payments required under noncancellable operating leases at March 31, 2021 (in thousands): Remainder of 2021 $ 796 2022 1,192 2023 1,201 2024 1,223 2025 1,259 2026 657 2027 59 Total operating lease obligations $ 6,387
Schedule of Future Annual Minimum Payments Under Capitalized Lease	The following table presents the future annual minimum payments under the capitalized lease, together with the present value of net minimum lease payments at March 31, 2021 (in thousands): Remainder of 2021 $ 31 2022 41 2023 41 2024 14 Total capital lease obligations 127 Less amount representing interest (16 ) Present value of minimum capital lease obligations $ 111

Equity (Tables)

Equity (Tables)	3 Months Ended
	Mar. 31, 2021
Summary of Common Stock Warrant Activity	The following is a summary of the employee-issued common stock warrant activity during the three months ended March 31, 2021 Number of Common Stock Warrants Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2020 57,212 $ 7.62 3.64 $ 98 Granted — $ — Exercised — $ — Expired — $ — Outstanding and exercisable at March 31, 2021 57,212 $ 7.62 3.39 $ 495
Warrant | Equity and Debt Fundraising Events
Summary of Common Stock Warrant Activity	The following is a summary of the common stock warrant activity related to common stock warrants issued in conjunction with equity and debt fundraising events for the three months ended March 31, 2021: Number of Common Stock Warrants Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2020 412,262 $ 9.60 6.71 $ 1,380 Granted 1,648,709 $ 0.01 Exercised (1,648,709 ) $ (0.01 ) Expired — $ — Outstanding at March 31, 2021 412,262 $ 9.60 6.47 $ 4,122

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Option Award Activity	The following is a summary of the stock option award activity during the three months ended March 31, 2021: Number of Stock Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2020 1,947,123 $ 5.70 9.56 $ 10,284 Granted 1,253,825 $ 18.06 Exercised — $ — Forfeited (43,749 ) $ (6.00 ) Expired — $ — Outstanding at March 31, 2021 3,157,199 $ 10.60 9.50 $ 23,557 Exercisable at March 31, 2021 446,771 $ 15.70 9.04 $ 5,096 Options expected to vest as of March 31, 2021 2,710,428 $ 9.76 9.62 $ 18,461
Summary of Common Stock Warrant Activity	The following is a summary of the employee-issued common stock warrant activity during the three months ended March 31, 2021 Number of Common Stock Warrants Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2020 57,212 $ 7.62 3.64 $ 98 Granted — $ — Exercised — $ — Expired — $ — Outstanding and exercisable at March 31, 2021 57,212 $ 7.62 3.39 $ 495
Summary of Fair Value Assumptions and Methodology	The following table presents the assumptions and the Company’s methodology for developing each of the assumptions used: Three Months Ended March 31, 2021 Volatility 91.5%-98.04% Expected life (years) 5.52-6.08 Risk-free interest rate 0.5%–1.0% Dividend rate —%
Summary of Stock-Based Compensation Expense	Stock-based compensation expense was recorded in the following line items in the condensed consolidated statements of operations for the three months ended March 31, 2021 and 2020 (in thousands): Three Months Ended March 31, 2021 2020 Research and development $ 509 $ 51 General and administrative 840 143 Total stock-based compensation expense $ 1,349 $ 194

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share	Basic and diluted net loss per share attributable to common stockholders is calculated as follows (in thousands except share and per share amounts): Three Months Ended March 31, 2021 2020 Net loss $ (7,972 ) $ (4,692 ) Cumulative dividends on convertible preferred stock — (104 ) Net loss attributable to common stockholders $ (7,972 ) $ (4,796 ) Net loss per share—basic and diluted $ (0.42 ) $ (4.00 ) Weighted-average number of shares used in computing net loss per share—basic and diluted 18,904,853 1,199,550
Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share	The following outstanding potentially dilutive securities have been excluded from the calculation of diluted net loss per share, as their effect is anti-dilutive: Three Months Ended March 31, 2021 2020 Convertible preferred stock — 527,138,337 Stock options to purchase common stock 3,157,199 1,947,123 Warrants issued to employees and contractor to purchase common stock 57,212 57,420 Warrants issued related to convertible notes and other equity agreements 412,262 22,937

Organization and Operations - A

Organization and Operations - Additional Information (Details) $ / shares in Units, $ in Thousands	Jan. 29, 2021	Feb. 28, 2021USD ($)$ / sharesshares	Mar. 31, 2021USD ($)shares	Mar. 31, 2020USD ($)	Dec. 31, 2020USD ($)
Subsidiary Sale Of Stock [Line Items]
Net loss			$ (7,972)	$ (4,692)
Accumulated deficit			(120,384)		$ (112,412)
Cash and cash equivalents			$ 169,418		$ 16,596
Reverse stock split description			On January 29, 2021, the Company effected a reverse stock split of the Company’s common stock on a 48-for-1 basis (the “Reverse Stock Split”).
Reverse stock split conversion ratio	0.020833
Common Stock
Subsidiary Sale Of Stock [Line Items]
Common stock shares issued and sold | shares			8,030,295
IPO | Common Stock
Subsidiary Sale Of Stock [Line Items]
Common stock shares issued and sold | shares		8,030,295
Share price per share | $ / shares		$ 19
Proceeds from issuance initial public offering		$ 152,600
Net proceeds after deducting underwriting discounts and estimated offering expenses		$ 138,500

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details)	Dec. 31, 2020
ASU 2018-13
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2020
Change in accounting principle, accounting standards update, immaterial effect	true
ASU 2019-12
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 1, 2020
Change in accounting principle, accounting standards update, immaterial effect	true

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Total property and equipment	$ 2,348	$ 1,861
Less accumulated depreciation and amortization	(693)	(595)
Property and equipment, net	1,655	1,266
Office Equipment and Furniture
Property Plant And Equipment [Line Items]
Total property and equipment	121	94
Research Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 2,227	$ 1,767

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 98	$ 23

Other Current Liabilities - Sum

Other Current Liabilities - Summary of Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Other Liabilities Disclosure [Abstract]
Compensation and benefits	$ 440	$ 916
Other	33	32
Total other current liabilities	$ 473	$ 948

Debt - Additional Information (

Debt - Additional Information (Details) - PPP Loan - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	May 31, 2020
Debt Instrument [Line Items]
Debt instrument, face amount		$ 567
Debt instrument, interest rate		1.00%
Debt instrument, frequency of periodic payment of principal and interest	monthly
Loan forgiveness description	the Company applies for forgiveness before August 2021 and forgiveness is not granted, principal and interest payments will be required beginning in May 2022. If the Company does not apply for loan forgiveness by August 2021, principal and interest will be required beginning in August 2021

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details)	3 Months Ended
	Mar. 31, 2020USD ($)
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value adjustments on embedded debt derivatives	$ 995,000
Fair value, transfer of assets, from level 1 to level 2	0
Fair value, transfer of assets from level 2 to level 1	0
Fair value, transfer of liabilities, from level 1 to level 2	0
Fair value, transfer of liabilities from level 2 to level 1	0
Fair value, transfer of assets into level 3	0
Fair value, transfer of assets out of level 3	0
Fair value, transfer of liabilities into level 3	0
Fair value, transfer of liabilities out of level 3	0
Other income
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value adjustments on embedded debt derivatives	$ 1,000,000

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Reconciliation of Embedded Debt Derivatives Measured Fair Value on Recurring Basis (Details) - Fair Value of Recurring - Level 3 $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance at December 31, 2019	$ 3,920
Change in fair value	(995)
Settlement	$ (2,925)

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2021USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2017USD ($)Officer
Commitments And Contingencies Disclosure [Abstract]
Lease expiration year	2027
Operating lease, expense	$ 234,000	$ 304,000
Letters of credit agreements outstanding amount	$ 515,000
Number of former officers | Officer			2
Loss contingency allegations claims			$ 0
Loss contingency, allegations	The Company believes that there is no merit to the claims alleged against the Company and its former officers, including no alleged breach of contract by the Company, and intends to vigorously defend against the claims pertaining to the Company and its former officers.

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Annual Minimum Payments Under Noncancellable Operating Lease (Details) $ in Thousands	Mar. 31, 2021USD ($)
Commitments And Contingencies Disclosure [Abstract]
Remainder of 2021	$ 796
2022	1,192
2023	1,201
2024	1,223
2025	1,259
2026	657
2027	59
Total operating lease obligations	$ 6,387

Commitments and Contingencies_3

Commitments and Contingencies - Schedule of Future Annual Minimum Payments Under Capitalized Lease (Details) $ in Thousands	Mar. 31, 2021USD ($)
Commitments And Contingencies Disclosure [Abstract]
Remainder of 2021	$ 31
2022	41
2023	41
2024	14
Total capital lease obligations	127
Less amount representing interest	(16)
Present value of minimum capital lease obligations	$ 111

Equity - Additional Information

Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 08, 2021	Feb. 28, 2021	Jan. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Common stock, shares authorized				1,230,000,000	1,230,000,000
IPO
Class Of Stock [Line Items]
Common stock shares issued and sold		8,030,295
Partial exercise of the underwriters’ option to purchase additional shares		1,030,243
Sale of Stock, Price Per Share		$ 19
Aggregate gross proceeds from issuance of initial public offering		$ 152.6
Net proceeds after deducting underwriting discounts		$ 138.5
Outstanding preferred stock converted into aggregate shares of common stock	19,034,069
Common stock, shares authorized	250,000,000
Preferred stock, shares authorized	10,000,000
Series BB Convertible Preferred Stock Issuance
Class Of Stock [Line Items]
Convertible preferred stock shares issued and sold			113,275,902
Convertible preferred stock per share			$ 0.207383
Proceeds on the issuance of convertible preferred stock			$ 23.5

Equity - Summary of Common Stoc

Equity - Summary of Common Stock Warrant activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Number of Common Stock Warrants Outstanding, Beginning Balance	57,212
Number of Common Stock Warrants Outstanding, Ending Balance		57,212
Weighted-Average Exercise Price Outstanding, Beginning Balance	$ 7.62
Weighted-Average Exercise Price Outstanding, Ending Balance		$ 7.62
Weighted-Average Remaining Contractual Term, Outstanding		3 years 7 months 20 days
Aggregate Intrinsic Value Outstanding		$ 98
Warrant | Equity and Debt Fundraising Events
Class Of Stock [Line Items]
Number of Common Stock Warrants Outstanding, Beginning Balance	412,262
Number of Common Stock Warrants, Granted	1,648,709
Number of Common Stock Warrants, Exercised	(1,648,709)
Number of Common Stock Warrants Outstanding, Ending Balance	412,262	412,262
Weighted-Average Exercise Price Outstanding, Beginning Balance	$ 9.60
Weighted Average Exercise Price, Granted	0.01
Weighted Average Exercise Price, Exercised	(0.01)
Weighted-Average Exercise Price Outstanding, Ending Balance	$ 9.60	$ 9.60
Weighted-Average Remaining Contractual Term, Outstanding	6 years 5 months 19 days	6 years 8 months 15 days
Aggregate Intrinsic Value Outstanding	$ 4,122	$ 1,380

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021USD ($)$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant dates at weighted average fair value | $ / shares	$ 18.06
Options vested | $	$ 1,100,000
Unrecognized stock-based compensation expense | $	$ 21,400,000
Weighted-average period	3 years 6 months 18 days
Common Stock Warrants
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense | $	$ 0
2021 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for issuance | shares	5,000,000
Number of capital stock outstanding percentage	4.00%
Grant dates at weighted average fair value | $ / shares	$ 13.84
2021 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for issuance | shares	333,333
Percentage of number of shares of capital stock outstanding on last day of preceding year	1.00%
2018 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant dates at weighted average fair value | $ / shares	$ 13.84

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Award Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Stock Options, Outstanding balance	1,947,123
Number of Stock Options, Granted	1,253,825
Number of Stock Options, Forfeited	(43,749)
Number of Stock Options, Outstanding balance	3,157,199	1,947,123
Number of Stock Options, Exercisable	446,771
Number of Stock Options, Options expected to vest	2,710,428
Weighted-Average Exercise Price, Outstanding balance	$ 5.70
Grant dates at weighted average fair value	18.06
Weighted-Average Exercise Price, Forfeited	(6)
Weighted-Average Exercise Price,Outstanding balance	10.60	$ 5.70
Weighted-Average Exercise Price, Exercisable	15.70
Weighted-Average Exercise Price, Options expected to vest	$ 9.76
Weighted-Average Remaining Contractual Term, Outstanding balance	9 years 6 months	9 years 6 months 21 days
Weighted-Average Remaining Contractual Term, Exercisable	9 years 14 days
Weighted-Average Remaining Contractual Term, Options expected to vest	9 years 7 months 13 days
Aggregate Intrinsic Value, Outstanding	$ 23,557	$ 10,284
Aggregate Intrinsic Value, Exercisable	5,096
Aggregate Intrinsic Value, Options expected to vest	$ 18,461

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Employee-issued Common Stock Warrant Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Common Stock Warrants Outstanding, Beginning Balance	57,212
Number of Common Stock Warrants Outstanding and Exercisable, Ending Balance	57,212
Weighted-Average Exercise Price Outstanding, Beginning Balance	$ 7.62
Weighted-Average Exercise Price Outstanding and Exercisable, Ending Balance	$ 7.62
Weighted-Average Remaining Contractual Term Outstanding		3 years 7 months 20 days
Weighted-Average Remaining Contractual Term Outstanding and Exercisable	3 years 4 months 20 days
Aggregate Intrinsic Value Outstanding	$ 98
Aggregate Intrinsic Value Outstanding and Exercisable	$ 495

Stock-Based Compensation - Su_3

Stock-Based Compensation - Summary of Fair Value Assumptions and Methodology (Details)	3 Months Ended
	Mar. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility, Minimum	91.50%
Volatility, Maximum	98.04%
Risk-free interest rate, Minimum	0.50%
Risk-free interest rate, Maximum	1.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)	5 years 6 months 7 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life (years)	6 years 29 days

Stock-Based Compensation - Su_4

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,349	$ 194
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	509	51
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 840	$ 143

Employee Retirement Plan - Addi

Employee Retirement Plan - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Company's matching contributions vesting percentage	100.00%
Accrued expense	$ 29	$ 26
Maximum
Defined Benefit Plan Disclosure [Line Items]
Percentage of company matching contributions of employee's base salary	4.00%

Related-Party Transactions - Ad

Related-Party Transactions - Additional Information (Details) - Consulting Agreement - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Consulting services fee		$ 1,500
Consultation service fee payment	$ 1,125
Remaining consultation fee recorded as expense	$ 375

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 0	$ 0

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Net loss	$ (7,972)	$ (4,692)
Cumulative dividends on convertible preferred stock		(104)
Net loss attributable to common stockholders	$ (7,972)	$ (4,796)
Net loss per common share, basic and diluted	$ (0.42)	$ (4)
Weighted-average number of shares used in computing net loss per common share, basic and diluted	18,904,853	1,199,550

Net Loss Per Share - Potentiall

Net Loss Per Share - Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share		527,138,337
Stock Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share	3,157,199	1,947,123
Warrants Issued to Employees and Contractor to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share	57,212	57,420
Warrants Issued Related to Convertible Notes and Other Equity Agreements
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share	412,262	22,937