0001564590-21-014593 | 10-K | XBRL Viewer

Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2020	Mar. 19, 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	Spruce Biosciences, Inc.
Entity Central Index Key	0001683553
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
Entity Common Stock, Shares Outstanding		23,301,872
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	SPRB
Security Exchange Name	NASDAQ
Entity File Number	001-39594
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-2154263
Entity Address, Address Line One	2001 Junipero Serra Boulevard
Entity Address, Address Line Two	Suite 640
Entity Address, City or Town	Daly City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94014
City Area Code	415
Local Phone Number	655-4168
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	false
Documents Incorporated by Reference	Portions of the Registrant’s definitive Proxy Statement for its 2021 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission pursuant to Regulation 14A not later than 120 days after the end of the fiscal year covered by this Annual Report on Form 10-K are incorporated by reference in Part III, Items 10-14 of this Annual Report on Form 10-K.

BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 157,150	$ 3,924
Prepaid expenses	2,971	215
Other current assets	276	513
Total current assets	160,397	4,652
Restricted cash	216
Right-of-use assets	1,793
Other assets	477	40
Total assets	162,883	4,692
Current liabilities:
Accounts payable	3,628	1,878
Term loan, current portion	2,554	1,252
Accrued expenses and other current liabilities	2,496	265
Accrued compensation and benefits	1,085	908
Total current liabilities	9,763	4,303
Term loan, net of current portion	1,922	3,193
Lease liability, net of current portion	1,653
Other liabilities	118	20
Total liabilities	13,456	7,516
Commitments and contingencies (Note 7)
Stockholders’ equity (deficit):
Preferred stock, $0.0001 par value; 10,000,000 shares and 0 shares authorized as of December 31, 2020 and 2019, respectively; 0 shares issued and outstanding as of December 31, 2020 and 2019
Common stock, $0.0001 par value; 200,000,000 shares and 41,000,000 shares authorized as of December 31, 2020 and 2019, respectively; 23,260,399 shares and 764,408 shares issued and outstanding as of December 31, 2020 and 2019, respectively	2	1
Additional paid-in capital	210,266	664
Accumulated deficit	(60,841)	(31,302)
Total stockholders’ equity (deficit)	149,427	(30,637)
Total liabilities, redeemable convertible preferred stock and stockholders’ equity (deficit)	$ 162,883	4,692
Series A Redeemable Convertible Preferred Stock
Current liabilities:
Series A redeemable convertible preferred stock, $0.0001 par value; 0 shares and 28,000,000 shares authorized, issued and outstanding as of December 31, 2020 and 2019, respectively; liquidation preference of $0 and $28,000 as of December 31, 2020 and 2019, respectively		$ 27,813

BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Preferred Stock, Par Value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	41,000,000
Common stock, shares issued	23,260,399	764,408
Common stock, shares outstanding	23,260,399	764,408
Series A Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value	$ 0.0001	$ 0.0001
Redeemable convertible preferred stock, shares authorized	0	28,000,000
Redeemable convertible preferred stock, shares issued	0	28,000,000
Redeemable convertible preferred stock, shares outstanding	0	28,000,000
Redeemable convertible preferred stock, liquidation preference	$ 0	$ 28,000

STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development	$ 23,854	$ 10,817
General and administrative	5,562	2,290
Total operating expenses	29,416	13,107
Loss from operations	(29,416)	(13,107)
Interest expense	(323)	(65)
Other income, net	200	84
Net loss	$ (29,539)	$ (13,088)
Net loss per share, basic and diluted	$ (4.93)	$ (17.12)
Weighted-average shares of common stock outstanding, basic and diluted	5,991,213	764,408

STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Initial Public Offering	Series A Redeemable Convertible Preferred Stock	Series A Redeemable Convertible Preferred Stock Initial Public Offering	Series B Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock Initial Public Offering	Common Stock	Common Stock Initial Public Offering	Additional Paid-In Capital	Additional Paid-In Capital Initial Public Offering	Accumulated Deficit
Balance at Dec. 31, 2018			$ 19,872
Balance, Shares at Dec. 31, 2018			20,000,000
Balance at Dec. 31, 2018	$ (17,802)						$ 1		$ 411		$ (18,214)
Balance, Shares at Dec. 31, 2018							764,408
Issuance of redeemable convertible preferred stock, net of issuance costs			$ 7,941
Issuance of redeemable convertible preferred stock, net of issuance costs, Shares			8,000,000
Stock-based compensation	196								196
Issuance of warrant to purchase common stock	57								57
Net loss	(13,088)										(13,088)
Balance at Dec. 31, 2019			$ 27,813
Balance, Shares at Dec. 31, 2019			28,000,000
Balance at Dec. 31, 2019	$ (30,637)						$ 1		664		(31,302)
Balance, Shares at Dec. 31, 2019	764,408						764,408
Issuance of redeemable convertible preferred stock, net of issuance costs					$ 87,633
Issuance of redeemable convertible preferred stock, net of issuance costs, Shares					73,333,330
Temporary equity, Conversion of redeemable convertible preferred stock into common stock upon initial public offering				$ (27,813)		$ (87,633)
Temporary equity, Conversion of redeemable convertible preferred stock into common stock upon initial public offering, Shares				(28,000,000)		(73,333,330)
Conversion of redeemable convertible preferred stock into common stock upon initial public offering		$ 115,446						$ 1		$ 115,445
Conversion of redeemable convertible preferred stock into common stock upon initial public offering, Shares	46,358							15,492,019
Initial public offering of common stock, net of underwriting expenses and offering costs		$ 93,351								$ 93,351
Initial public offering of common stock, net of underwriting expenses and offering costs, Shares								6,900,000
Exercise of common stock options	$ 51								51
Exercise of common stock options, Shares							57,614
Exercise of common stock warrant, Shares							46,358
Stock-based compensation	755								755
Net loss	(29,539)										(29,539)
Balance, Shares at Dec. 31, 2020			0
Balance at Dec. 31, 2020	$ 149,427						$ 2		$ 210,266		$ (60,841)
Balance, Shares at Dec. 31, 2020	23,260,399						23,260,399

STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Underwriting expenses and offering costs	$ 10,149
Series A Convertible Preferred Stock
Stock issuance costs		$ 60
Series B Convertible Preferred Stock
Stock issuance costs	$ 367

STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities
Net loss	$ (29,539)	$ (13,088)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	755	196
Depreciation and amortization	36	12
Non-cash lease expense	66
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(2,883)	(67)
Accounts payable and accrued expenses	3,733	(226)
Accrued compensation and benefits	177	572
Other assets	(6)	(36)
Other liabilities	142	20
Net cash used in operating activities	(27,519)	(12,617)
Cash flows from investing activities
Purchases of property and equipment	(74)	(4)
Net cash used in investing activities	(74)	(4)
Cash flows from financing activities
Proceeds from initial public offering, net of underwriting discounts and commissions	96,255
Payment of issuance costs for initial public offering	(2,904)
Proceeds from exercise of common stock options	51
Proceeds from issuance of term loan, net of issuance costs		4,492
Net cash provided by financing activities	181,035	12,433
Net increase (decrease) in cash, cash equivalents and restricted cash	153,442	(188)
Cash, cash equivalents, and restricted cash at beginning of period	3,924	4,112
Cash, cash equivalents, and restricted cash at end of period	157,366	3,924
Supplemental cash flow data:
Cash paid for interest	192	20
Supplemental disclosure of non-cash investing and financing activities:
Right-of-use assets recognized in exchange for lease liabilities	1,858
Fair value of common stock warrant issued in connection with term loan		57
Series A Redeemable Convertible Preferred Stock
Cash flows from financing activities
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs		$ 7,941
Supplemental disclosure of non-cash investing and financing activities:
Conversion of redeemable convertible preferred stock to common stock upon initial public offering	27,813
Series B Redeemable Convertible Preferred Stock
Cash flows from financing activities
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	87,633
Supplemental disclosure of non-cash investing and financing activities:
Conversion of redeemable convertible preferred stock to common stock upon initial public offering	$ 87,633

STATEMENTS OF CASH FLOWS (Parenthetical) $ in Thousands	12 Months Ended
STATEMENTS OF CASH FLOWS (Parenthetical) $ in Thousands	Dec. 31, 2019 USD ($)
Statement Of Cash Flows [Abstract]
Proceeds from issuance of term loan, issuance costs	$ 8

Organization and Principal Activities

12 Months Ended

Dec. 31, 2020

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Principal Activities

1. Organization and Principal Activities

Description of Business

Spruce Biosciences, Inc. (the Company) is a late-stage biopharmaceutical company focused on developing and commercializing novel therapies for rare endocrine disorders with significant unmet medical need. The Company is initially developing its wholly-owned product candidate, tildacerfont, as the potential first non-steroidal therapy to offer markedly improved disease control and reduce steroid burden for patients suffering from classic congenital adrenal hyperplasia (CAH) and a rare form of polycystic ovary syndrome (PCOS). The Company is located in Daly City, California and was incorporated in the state of Delaware in April 2016.

Reverse Stock Split

In October 2020, the Company filed an amendment to the Company’s amended and restated certificate of incorporation to effect a reverse split of shares of the Company’s common stock on a 1-for-6.541 basis (Reverse Stock Split). Adjustments corresponding to the Reverse Stock Split were made to the ratio at which the Company’s redeemable convertible preferred stock converted into common stock in connection with the closing of the initial public offering (IPO). The par value of the common stock and number of shares authorized were not adjusted as a result of the Reverse Stock Split. All references to common stock, options to purchase common stock, warrants, share data, per share data, and related information contained in the financial statements and related footnotes have been retrospectively adjusted to reflect the effect of the Reverse Stock Split for all periods presented.

Initial Public Offering

In October 2020, the Company consummated its IPO and issued a total of 6,900,000 shares of common stock, which includes 900,000 shares issued pursuant to the exercise of the underwriters’ option to purchase additional shares, at an offering price of $15.00 per share. In aggregate, the Company received net proceeds of $93.4 million, after deducting underwriting discounts and commissions and offering expenses. Upon the closing of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock automatically converted into 15,492,019 shares of common stock.

Liquidity and Capital Resources

As of December 31, 2020, the Company had cash and cash equivalents of $157.2 million, which is sufficient to fund its planned operations for a period of at least twelve months following the issuance of the accompanying financial statements.

The Company has incurred significant losses and negative cash flows from operations. During the year ended December 31, 2020, the Company incurred a net loss of $29.5 million and used $27.5 million of cash in operations. As of December 31, 2020, the Company had an accumulated deficit of $60.8 million and does not expect positive cash flows from operations in the foreseeable future. The Company has funded its operations primarily through the issuance and sale of redeemable convertible preferred stock, debt, and the IPO. In February 2020, the Company issued and sold 36,666,665 shares of Series B redeemable convertible preferred stock (Series B preferred stock) for approximately $43.6 million in net proceeds. In August 2020, the Company issued and sold an additional 36,666,665 shares of Series B preferred stock for approximately $44.0 million in net proceeds.

The Company anticipates that it will need to raise substantial additional financing in the future to fund its operations. In order to meet these additional cash requirements, the Company may seek to sell additional equity or issue debt, convertible debt or other securities that may result in dilution to its stockholders. If the Company raises additional funds through the issuance of debt or convertible debt securities, these securities could have rights senior to those of its shares of common stock and could contain covenants that restrict its operations. There can be no assurance that the Company will be able to obtain additional equity or debt financing on terms acceptable to it, if at all. Debt financing, if available, would result in increased fixed payment obligations and may involve agreements that include covenants limiting or restricting the Company’s ability to take specific actions such as incurring debt, making capital expenditures or declaring dividends. The Company’s failure to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on its business, results of operations, and financial condition.

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

Basis of Presentation

The financial statements and accompanying notes have been prepared in accordance with generally accepted accounting principles in the United States (U.S. GAAP) and include all adjustments necessary for the fair presentation of the Company’s financial position for the periods presented.

Use of Estimates

The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and expenses as well as related disclosure of contingent assets and liabilities. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, accrued research and development expenses, valuation of common stock and stock-based compensation, valuation of warrants and income tax and uncertain tax positions. The Company bases its estimates on its historical experience and on assumptions that it believes are reasonable; however, actual results could significantly differ from those estimates.

Risks and Uncertainties

Any product candidates developed by the Company will require approvals from the U.S. Food and Drug Administration (FDA) or foreign regulatory agencies prior to commercial sales. There can be no assurance that the Company’s current and future product candidates will meet desired efficacy and safety requirements to obtain the necessary approvals. If approval is denied or delayed, it may have a material adverse impact on the Company’s business and its financial statements.

The Company is subject to a number of risks similar to other late-stage biopharmaceutical companies including, but not limited to, dependency on the clinical and commercial success of the Company’s product candidate, tildacerfont, ability to obtain regulatory approval of tildacerfont, the need for substantial additional financing to achieve its goals, uncertainty of broad adoption of its approved products, if any, by physicians and consumers, significant competition and untested manufacturing capabilities, and dependence on key individuals and sole source suppliers.

The Company’s business has been and could continue to be adversely affected by the evolving COVID-19 pandemic. For example, the COVID-19 pandemic has resulted in and could result in delays to the Company’s clinical trials for numerous reasons including additional delays or difficulties in enrolling patients, diversion of healthcare resources away from the conduct of clinical trials, interruption or delays in the operations of the FDA or other regulatory authorities, and delays in clinical sites receiving the supplies and materials to conduct our clinical trials. At this time, the extent to which the COVID-19 pandemic impacts the Company’s business will depend on future developments, which are highly uncertain. The Company will continue to evaluate the impact that these events could have on its future operations, financial position, and results of operations and cash flows.

Segment Reporting

The Company operates and manages its business as one operating segment, which is the business of designing and developing novel therapies for rare endocrine disorders. The Company’s chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for allocating and evaluating financial performance. All long-lived assets are maintained in the United States of America.

Cash and Cash Equivalents

The Company considers all highly liquid investments with remaining maturities at the date of purchase of three months or less to be cash equivalents. Cash equivalents consist of amounts invested in money market funds.

Restricted Cash

The Company has cash in a collateral account related to a letter of credit issued on behalf of the Company for the security deposit on the non-cancelable operating lease for an office facility. The collateralized cash in connection with the letter of credit was classified as restricted cash on the balance sheet as of December 31, 2020 based on the terms of the lease agreement, which expires in 2025, unless extended.

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed statements of cash flows (in thousands):

	December 31,
	2020		2019
Cash and cash equivalents	$	157,150	$	3,924
Restricted cash		216		—
Total cash, cash equivalents and restricted cash	$	157,366	$	3,924

Fair Value of Financial Instruments

Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability, or an exit price, in the principal or most advantageous market for that asset or liability in an orderly transaction between market participants on the measurement date. Fair value measurement establishes a fair value hierarchy that requires an entity to maximize the use of observable inputs, where available, and minimize the use of unobservable inputs when measuring fair value.

The Company determined the fair value of financial assets and liabilities using the fair value hierarchy that describes three levels of inputs that may be used to measure fair value, as follows:

▪

Level 1—Quoted prices in active markets for identical assets and liabilities;

▪

Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and

▪

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

The Company’s financial instruments primarily consist of cash and cash equivalents, prepaid expenses, accounts payable, term loan, and accrued expenses. The carrying value of cash and cash equivalents, prepaid expenses, accounts payable, and accrued expenses are generally considered to be representative of their respective fair values because of the short-term nature of those instruments. The estimated fair value of the term loan is based on estimated interest rates currently available to the Company for debt with similar terms.

Concentration of Credit Risk

Financial instruments, which potentially subject the Company to significant concentration of credit risk, consist primarily of cash and cash equivalents. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company is exposed to credit risk in the event of default by the financial institutions holding its cash and cash equivalents to the extent recorded in the balance sheet. The Company has not experienced any losses in such accounts and management believes that the Company is not exposed to significant credit risk due to the financial position of the depository institutions in which those deposits are held.

Leases

The Company adopted Accounting Standards Update (ASU), No. 2016-02, Leases (Topic 842) effective January 1, 2020.

The Company determines if an arrangement includes a lease at inception. Right-of-use assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. The right-of-use asset includes any lease payments made and excludes lease incentives. The incremental borrowing rate is used in determining the present value of future payments. The Company utilizes its incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. The lease terms may include options to extend or terminate the lease. Lease expense for minimum lease payments is recognized on a straight-line basis over the non-cancelable lease term. The Company has elected not to recognize a right-of-use asset and lease liability for short-term leases. A short-term lease is a lease with an expected lease term of 12 months or less and which does not include an option to purchase the underlying asset that the lessee is reasonably certain to exercise. The Company also elected the package of practical expedients under the transition guidance that will retain the historical lease classification and initial direct costs for any leases that exist prior to adoption of the new guidance and the practical expedient to not separate lease and non-lease components. Prior period amounts have not been adjusted and continue to be reported in accordance with the Company’s historical accounting under previous lease guidance, Accounting Standards Codification (ASC) 840, Leases (Topic 840). See Note 4 to these financial statements for additional detail.

During 2019, leases were accounted for under ASC 840, Leases, and classified as operating leases. The Company’s operating lease agreements include scheduled rent escalations over the lease term. During 2019, rent expense was charged ratably on a straight-line basis over the life of the lease from the date the Company obtains the legal right to use and control the leased space.

Redeemable Convertible Preferred Stock

The Company records redeemable convertible preferred stock at fair value on the dates of issuance, net of issuance costs. Upon the occurrence of certain events that are outside the Company’s control, including a deemed liquidation event such as a merger, acquisition and sale of all or substantially all of the Company’s assets, holders of the redeemable convertible preferred stock can cause redemption for cash. Therefore, redeemable convertible preferred stock is classified as temporary equity (mezzanine) on the balance sheet as events triggering the liquidation preferences are not solely within the Company’s control. The carrying values of the redeemable convertible preferred stock are adjusted to their liquidation preferences if and when it becomes probable that such a liquidation event will occur. Upon the consummation of the IPO, all shares of redeemable convertible preferred stock outstanding were automatically converted into 15,492,019 shares of common stock.

Research and Development Expenses

Research and development costs are expensed as incurred. Research and development expenses include, but are not limited to, personnel costs, fees paid to external entities that conduct certain non-clinical and clinical development activities on our behalf, manufacturing costs, outside service and consulting costs, and allocated overhead, including rent. Assets acquired that are utilized in research and development that have no alternative future use are also expensed as incurred.

Accrued Research and Development Expenses

Clinical trial costs are charged to research and development expense as incurred. The Company accrues for expenses resulting from contracts with clinical research organizations (CROs), consultants, and clinical site agreements in connection with conducting clinical trials. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to us under such contracts. The Company’s policy is to reflect the appropriate expense in the financial statements by matching the appropriate expenses with the period in which services and efforts are expended.

The CRO contracts generally include pass-through fees including, but not limited to, regulatory expenses, investigator fees, laboratory fees and other miscellaneous costs. The Company determines accrual estimates through reports from and discussion with clinical personnel and outside services providers as to the progress or state of completion of trials, or the services completed. The Company estimates accrued expenses as of each balance sheet date based on the facts and circumstances known at that time. The clinical trial accrual is dependent, in part, upon the receipt of timely and accurate reporting from the CROs and other third-party vendors.

If the actual timing of the performance of services or the level of effort varies from the original estimates, the Company will adjust the accrual accordingly. Payments associated with licensing agreements to acquire exclusive licenses to develop, use, manufacture and commercialize products that have not reached technological feasibility and do not have alternate commercial use are expensed as incurred. Payments made to third parties under these arrangements in advance of the performance of the related services by the third parties are recorded as prepaid expenses until the services are rendered.

Patent Costs

Costs related to filing and pursuing patent applications are expensed as incurred, as recoverability of such expenditures is uncertain. These costs are included in general and administrative expenses and were immaterial for each of the periods presented.

Income Taxes

The Company accounts for income taxes under the asset and liability method. The Company estimates actual current tax exposure together with assessing temporary differences resulting from differences in accounting for reporting purposes and tax purposes for certain items, such as accruals and allowances not currently deductible for tax purposes. These temporary differences result in deferred tax assets and liabilities. In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in the Company’s statements of operations become deductible expenses under applicable income tax laws or when net operating loss or credit carryforwards are utilized. Accordingly, realization of the Company’s deferred tax assets is dependent on future taxable income against which these deductions, losses and credits can be utilized.

The Company must assess the likelihood that the Company’s deferred tax assets will be recovered from future taxable income, and to the extent the Company believes that recovery is not likely, the Company establishes a valuation allowance. The assessment of whether or not a valuation allowance is required often requires significant judgment, including the forecast of future taxable income and on-going prudent and feasible tax planning initiatives. Based upon the weight of available evidence, the Company has determined that net deferred tax assets should be fully offset by a valuation allowance. When the Company establishes or reduces the valuation allowance against its net deferred tax assets, its provision for income taxes will increase or decrease, respectively, in the period such determination is made. As of December 31, 2020 and 2019, the Company maintains a full valuation allowance on its net deferred tax assets.

The Company recognizes benefits of uncertain tax positions if it is more likely than not that such positions will be sustained upon examination based solely on their technical merits, as the largest amount of benefit that is more likely than not to be realized upon the ultimate settlement. The Company’s policy is to recognize interest and penalties related to the underpayment of income taxes as a component of income tax expense or benefit. To date, there have been no interest or penalties charged in relation to unrecognized tax benefits.

Stock-Based Compensation

The Company has an equity incentive plan under which various types of equity-based awards including, but not limited to, incentive stock options, non-qualified stock options, and restricted stock awards, may be granted to employees, non-employee directors, and non-employee consultants.

For equity awards granted to employees and directors, the Company recognizes compensation expense based on the estimated grant-date fair values. The fair value of stock options is determined using the Black-Scholes option pricing model. The Company recognizes compensation expense for stock option awards on a straight-line basis over the requisite service period of the award, generally four years. Forfeitures are recorded as they occur.

Stock-based compensation expense related to stock options granted to nonemployees is recognized based on the fair value of the stock options, determined using the Black-Scholes option pricing model, as they are earned. The awards generally vest over the period the Company expects to receive services from the nonemployee. Non-employee stock-based compensation expense was not material in any period presented.

The Company’s determination of the fair value of stock options with time-based vesting on the date of grant utilizes the Black-Scholes option-pricing model and is impacted by its common stock price as well as other variables including, but not limited to, expected term that options will remain outstanding, expected common stock price volatility over the term of the option awards, risk-free interest rates and expected dividends. The fair value of a stock-based award is recognized over the period during which an optionee is required to provide services in exchange for the option award, known as the requisite service period (usually the vesting period) on a straight-line basis. Stock-based compensation expense is recognized based on the fair value determined on the date of grant and is reduced for forfeitures as they occur.

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, employee stock purchase plan and common stock warrants are considered to be potentially dilutive securities. Basic and diluted net loss attributable to common stockholders per share is presented in conformity with the two-class method required for participating securities as the redeemable convertible preferred stock is considered a participating security because it participates in dividends with common stock. The holders of all series of redeemable convertible preferred stock do not have a contractual obligation to share in the Company’s losses. As such, the net loss was attributed entirely to common stockholders. Because the Company has reported a net loss for all periods presented, diluted net loss per share is the same as basic net loss per share for those periods.

Commitments and Contingencies

From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of business. The Company evaluates the likelihood of an unfavorable outcome in legal or regulatory proceedings to which it is a party and records a loss contingency on an undiscounted basis when it is probable that a liability has been incurred and the amount of the loss can be reasonably estimated. These judgments are subjective and based on the status of such legal proceedings, the merits of the Company’s defenses, and consultation with legal counsel. Actual outcomes of these legal proceedings may differ materially from the Company’s estimates. The Company estimates accruals for legal expenses when incurred as of each balance sheet date based on the facts and circumstances known to the Company at that time.

Emerging Growth Company Status

The Company is an emerging growth company (EGC) as defined in the Jumpstart Our Business Startups Act of 2012 (JOBS Act) and may take advantage of reduced reporting requirements that are otherwise applicable to public companies. Section 107 of the JOBS Act exempts emerging growth companies from being required to comply with new or revised financial accounting standards until private companies are required to comply with those standards. The Company has elected to use the extended transition period for complying with new or revised accounting standards.

Recent Accounting Pronouncements Not Yet Adopted

In June 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2016-13, Measurement of Credit Losses on Financial Instruments (Topic 326): Measurement of Credit Losses on Financial Instruments. ASU 2016-13 requires companies to measure credit losses utilizing a methodology that reflects expected credit losses and requires a consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU 2016-13 is effective for non-EGC’s electing to use the extended transition period for complying with new or revised accounting standards for fiscal years beginning after December 15, 2019, and for EGC’s for fiscal years beginning after December 15, 2022, with early adoption permitted. The Company expects to adopt this ASU on January 1, 2023. The Company is currently assessing the impact of adopting this standard, but based on a preliminary assessment, does not expect the adoption of this guidance to have a material impact on its financial statements.

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes. The amendments in ASU 2019-12 are intended to simplify various aspects related to accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. ASU 2019-12 is effective for public business entities for fiscal years beginning after December 15, 2020 and the Company will adopt on January 1, 2021. The Company is currently assessing the impact of adopting this standard; however, it does not expect the adoption of this guidance to have a material impact on its financial statements.

Recently Adopted Accounting Pronouncements

In February 2016, the FASB issued ASU 2016-02, Leases. ASU 2016-02 requires a lessee to recognize right of use asset and lease liability for all leases with lease terms of more than 12 months, along with additional qualitative and quantitative disclosures. ASU 2016-02 is effective for the Company beginning January 1, 2022, with early adoption permitted. The Company elected the modified retrospective approach and adopted ASC 842 on January 1, 2020. The Company also elected the package of practical expedients under the transition guidance that will retain the historical lease classification and initial direct costs for any leases that exist prior to adoption of the new guidance and the practical expedient to not separate lease and non-lease components. As of the date of adoption, the Company did not have any leases subject to capitalization under ASC 842, and as such, there was no impact to the financial statements. Since adoption, the Company entered into a new lease and recorded a $1.9 million right-of-use asset and $1.9 million lease liability upon commencement of the lease in September 2020. See Note 5 for further disclosure.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820). This new guidance removes, modifies and adds to certain disclosure requirements on fair value measurements in Topic 820. This new guidance became effective for all entities for fiscal years beginning after December 15, 2019. Accordingly, the Company adopted ASU 2018-13 as of January 1, 2020. The adoption did not have any impact on the Company’s financial statements as of and for the year ended December 31, 2020.

Fair Value Measurements

12 Months Ended

Dec. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurements

3. Fair Value Measurements

The carrying amounts of cash equivalents approximate their fair value based upon quoted market prices. Certain of the Company’s financial instruments are not measured at fair value on a recurring basis but are recorded at amounts that approximate their fair value due to their liquid or short-term nature, such as cash, prepaid expenses, accounts payable and accrued expenses. The Company did not have any financial assets measured nor liabilities recorded at fair value on a recurring or non-recurring basis as of December 31, 2020 and 2019.

The estimated fair value of the term loan was $4.8 million as of December 31, 2020 and was based on estimated interest rates currently available to the Company for debt with similar terms, a Level 3 input.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Components

12 Months Ended

Dec. 31, 2020

Balance Sheet Components Disclosure [Abstract]

Balance Sheet Components

4. Balance Sheet Components

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Accrued research and development expenses	$	2,002	$	265
Accrued general and administrative expenses		245		—
Lease liability, current portion		249		—
Total accrued expenses and other current liabilities	$	2,496	$	265

Accrued research and development expenses were primarily related to clinical trials, preclinical studies, and manufacturing.

Leases

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Leases

5. Leases

The Company leases space under non-cancelable operating leases which require the Company to pay base rent, real estate taxes, insurance, general repairs, and maintenance. The Company does not have finance leases. As described in Note 2, the Company adopted ASC Topic 842 as of January 1, 2020.

In February 2020, the Company entered into a non-cancelable operating lease for office space with a commencement date of September 2020. The monthly payments escalate over the 63-month term with total gross commitments of $2.3 million. The lease includes an option to renew the lease term for an additional period of 60 months. The renewal option is not included in the lease term or minimum lease payments disclosures below as the Company is not reasonably certain to exercise the option. Lease incentives, which relate to rent abatement, were considered in the calculation of the lease liability and right-of-use asset. Lease expense for the year ended December 31, 2020 was $0.1 million.

In February 2019, the Company entered into a short-term lease for office space with a commencement date of March 2019. Total gross commitments over the 12-month term were $0.2 million. In February 2020, the Company extended the lease for an additional three months for a total of $42 thousand in additional commitments. The lease was terminated in May 2020.

Short-term lease expense for the year ended December 31, 2020 was $0.1 million. Rent expense for the year ended December 31, 2019 was $0.1 million and was recognized under prior Topic 840.

Lease right-of-use assets and liabilities are recognized at the commencement date based on the present value of the remaining minimum lease payments over the lease term, with certain adjustments as described in Note 2. As the leases do not provide an implicit rate, the Company uses a collateralized incremental borrowing rate based on the information available at the commencement date to determine the lease liability. As of December 31, 2020, the weighted-average remaining lease term for operating leases was 4.9 years and the weighted-average discount rate was 7.0%. Cash paid for amounts included in the measurement of lease liabilities was $37 thousand for the year ended December 31, 2020.

The Company recognizes monthly operating lease expense on a straight-line basis over the term of the lease. Variable lease expense relates primarily to office lease common area maintenance, insurance, and property taxes, is expensed as incurred, and is excluded from the calculation of the lease liability and right-of-use-asset. Variable lease expense for the year ended December 31, 2020 was minimal.

Future minimum annual lease commitments under the Company’s non-cancelable operating leases as of December 31, 2020 were as follows (in thousands):

	Amount
2021	$	377
2022		464
2023		478
2024		493
2025		464
Total undiscounted future minimum lease payments		2,276
Less: present value discount		(374	)
Total discounted future minimum lease payments	$	1,902
Lease liability, current portion (included in "accrued expenses and other current liabilities" on the condensed balance sheet)	$	249
Lease liability, net of current portion		1,653
Total operating lease liability	$	1,902

Term Loan

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Term Loan

6. Term Loan

In September 2019, the Company entered into a Loan and Security Agreement (the Loan Agreement) with Silicon Valley Bank (SVB) providing for a term loan (the Term Loan). In April 2020, the Company and SVB entered into an agreement (the Deferral Agreement) whereby the parties agreed to extend the Interest-Only Period (defined below), repayment dates of all monthly payments of principal due and the maturity date with respect to the Term Loan by six months. All other terms of the Term Loan remained unchanged. The Deferral Agreement was determined to be a debt modification, resulting in a prospective yield adjustment based on the revised terms.

Pursuant to the Loan Agreement, the Company had the ability to request up to $4.5 million of borrowings in two tranches of term loans. In September 2019, the Company requested $2.5 million from the first tranche (the First Tranche) in connection with the entry into the Loan Agreement. The Loan Agreement provided the option to request an additional $2.0 million (the Second Tranche), after the Company reached certain borrowing conditions as stipulated in the Loan Agreement. The Company satisfied these conditions and drew the Second Tranche of $2.0 million in December 2019. Pursuant to the Deferral Agreement, principal payments shall commence in January 2021 and the Term Loan will mature in September 2022.

Outstanding principal balances under the Term Loan bear interest at a floating per annum rate equal to the greatest of: (i) 1% below the prime rate, (ii) 4.25%, or (iii) 1% below the prime rate as of September 23, 2019. Under the Term Loan, as amended by the Deferral Agreement, the Company is required to make monthly payments of interest only commencing on the first day of the month following the funding date of each respective tranche and continuing thereafter through December 31, 2020 (the Interest-Only Period). Following the Interest-Only Period, the outstanding Term Loan balance will be payable in (i) 21 consecutive equal monthly payments of principal beginning on the first day of the calendar month after the end of the Interest-Only Period and continuing on the same day of each month thereafter, in amounts that would fully amortize such note balance, as of January 1, 2021, over the repayment period, plus (ii) monthly payments of accrued but unpaid interest. The final payment due on the maturity date shall include all outstanding principal and all accrued unpaid interest and an End of Term Payment totaling 6% of the combined principal amount of the First and Second Tranches, or $0.3 million. The End of Term Payment is being accrued through interest expense using the effective interest method. The Company may prepay amounts outstanding under the Term Loan at any time provided certain notification conditions are met, in which case, all outstanding principal plus accrued and unpaid interest, the End of Term Payment, a prepayment fee between 1% and 3% of the principal amount of the First and Second Tranches, and any bank expenses become due and payable.

In connection with the First and Second Tranches under the Loan Agreement, the Company issued a warrant to purchase up to an aggregate of 49,609 shares of common stock at $1.44 per share. The Company determined the initial fair value of the warrant to be $0.1 million using the Black-Scholes option-pricing model. The fair value of the warrant was recorded to equity and as a debt discount, which was being amortized to interest expense using the effective interest method over the term of the Term Loan. In November 2020, the warrant was net-exercised for 46,358 shares of common stock.

The Company also incurred $8 thousand of debt issuance costs in connection with the Term Loan, which is being amortized using the effective interest method over the life of the Term Loan. The unamortized debt issuance costs and debt discount balance was $24 thousand as of December 31, 2020.

The Term Loan and unamortized discount and debt issuance costs balances as of December 31, 2020 are shown below (in thousands):

	December 31, 2020
Total Term Loan debt	$	4,500
Less: unamortized discount and debt issuance costs		(24	)
Total Term Loan, net		4,476
Less: Term Loan, current portion		(2,554	)
Term loan, net of current portion	$	1,922

The Company is subject to customary affirmative and restrictive covenants under the Loan Agreement. The Company’s obligations under the Loan Agreement are secured by a first priority security interest in substantially all of its current and future assets, other than intellectual property. The Company also agreed not to encumber its intellectual property assets, except as permitted by the Loan Agreement.

The Loan Agreement also contains customary indemnification obligations and customary events of default, including, among other things, the Company’s failure to fulfill certain obligations under the Loan Agreement and the occurrence of a material adverse change in its business, operations, or condition (financial or otherwise), a material impairment of the prospect of repayment of any portion of the loan, or a material impairment in the perfection or priority of lender’s lien in the collateral or in the value of such collateral. In the event of default by the Company under the Loan Agreement, the lender would be entitled to exercise their remedies thereunder, including the right to accelerate the debt, upon which the Company may be required to repay all amounts then outstanding under the Loan Agreement. As of December 31, 2020, management believes that the Company was in compliance with all financial covenants under the Loan Agreement and there had been no material adverse change.

As of December 31, 2020, future principal payments per year under the Term Loan were as follows (in thousands):

	Amount
2021		2,571
2022		1,929
Total	$	4,500

The Company made interest payments on the Term Loan of $0.2 million during the year ended December 31, 2020.

As discussed in Note 14, the Loan Agreement was amended in March 2021.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

7. Commitments and Contingencies

Legal Matters

The Company’s industry is characterized by frequent claims and litigation, including claims regarding intellectual property. As a result, the Company may be subject to various legal proceedings from time to time. The results of any future litigation cannot be predicted with certainty, and regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources and other factors. The Company was not subject to any material legal proceedings during the year ended December 31, 2020 and management is not aware of any pending or threatened litigation.

Capital Structure

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Capital Structure

8. Capital Structure

Common Stock

As of December 31, 2020 and 2019, the Company was authorized to issue 200,000,000 and 41,000,000 shares of $0.0001 par value common stock, respectively. Holders of the Company’s common stock are entitled to dividends if and when declared by the Board of Directors of the Company (Board of Directors) and after any redeemable convertible preferred share dividends are fully paid. The holder of each share of common stock is entitled to one vote. As of December 31, 2020, no dividends were declared.

Common stock reserved for future issuance, on an as converted basis, consisted of the following:

	December 31,
	2020		2019
Series A redeemable convertible preferred stock		—		4,280,690
Stock options, issued and outstanding		2,278,771		859,322
Stock options, available for future issuance		2,637,076		4,598
Employee stock purchase plan, available for future issuance		220,640		—
Common stock warrant		—		49,609
Total shares reserved		5,136,487		5,194,219

Redeemable Convertible Preferred Stock

Immediately prior to the closing of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock converted into 15,492,019 shares of common stock and the related carrying value was reclassified to common stock and additional paid-in capital. There were no shares of redeemable convertible preferred stock outstanding as of December 31, 2020.

Issued and outstanding redeemable convertible preferred stock as of December 31, 2019, and its principal terms during the year then ended were as follows (in thousands, except share and per share amounts):

As of December 31, 2019

Series

Authorized

Issued and

Outstanding

Original

Issue Price

Per Share

Aggregate

Liquidation

Amount

Net

Carrying

Value

Series A redeemable convertible preferred stock

28,000,000

1.0000

28,000

27,813

During 2020, the Company authorized and issued 73,333,330 shares of Series B preferred stock at $1.20 per share for aggregate net proceeds of $87.6 million.

The holders of redeemable convertible preferred stock had various rights and preferences, including the following:

Liquidation Preference

In the event of any voluntary or involuntary liquidation, dissolution or winding up of the Company or deemed liquidation event, the holders of redeemable convertible preferred stock were entitled to be paid out of the assets of the Company, prior and in preference to any distribution to the holders of common stock, an amount equal to the original issuance price, meaning $1.00 per share for each share of Series A redeemable convertible preferred stock (Series A preferred stock) and $1.20 per share for each share of Series B preferred stock, plus all declared but unpaid dividends, if any.

If the assets available for distribution to stockholders were insufficient to pay the holders of shares of the redeemable convertible preferred stock the full amount to which they are entitled, then the entire assets of the Company legally available for distribution would be distributed ratably among the holders of redeemable convertible preferred stock in proportion to the respective amounts each such holder is otherwise entitled to receive.

After the payment to the holders of redeemable convertible preferred stock of the full preferential amount specified above, any remaining assets would be distributed pro rata to the holders of redeemable convertible preferred stock and common stock based upon the respective shares of common stock held by each holder (assuming conversion of all such redeemable convertible preferred stock into common stock). The redeemable convertible preferred stockholders were entitled to receive the greater of the maximum participation amount, meaning $4.00 per share for each share of Series A preferred stock and $4.80 per share for each share of Series B preferred stock, or the amount they would have received if all shares of redeemable convertible preferred stock were converted into common stock immediately prior to such liquidation, dissolution, or wind up.

Conversion

The shares of redeemable convertible preferred stock were convertible into such number of shares of common stock as is determined by dividing the original issue price by the applicable conversion price in effect at the time of conversion, at the option of the holder. The conversion price was initially equal to $6.541 per share for each share of Series A preferred stock and $7.849 per share for each share of Series B preferred stock, subject to certain anti-dilution adjustments. Additionally, each share of redeemable convertible preferred stock would be automatically converted into common stock (i) immediately prior to the closing of the Company’s sale of its common stock in a firm commitment underwritten public offering pursuant to a registration statement under the Securities Act of 1933, as amended, in which (a) the gross cash proceeds to the Corporation (before underwriting discounts, commissions and fees) were at least $50.0 million, (b) the price per share in the public offering was at least $15.6984 per share, and (c) the Company’s shares were listed for trading on the New York Stock Exchange, Nasdaq Global Select Market or Nasdaq Global Market, or (ii) upon the affirmative election of the holders of a majority shares of then-outstanding shares of redeemable convertible preferred stock, voting together as a single class on an as-converted basis, which majority must include the approval of certain holders of Series B preferred stock.

In October 2020, pursuant to the closing of the IPO, the holders of Series A and Series B redeemable convertible preferred stock elected to automatically convert all outstanding shares of Series A and Series B redeemable convertible preferred stock into the Company’s common stock, at the then-effective and applicable conversion rate.

Voting

The holders of redeemable convertible preferred stock were entitled to one vote for each share of common stock into which such redeemable convertible preferred stock could then be converted; and with respect to such vote, such holders have full voting rights and powers equal to the voting rights and powers of the holders of common stock in addition to certain separate voting requirements in favor of the holders of Series A preferred stock and Series B preferred stock.

The holders of Series A preferred stock, voting as a separate class, were entitled to elect two directors to the Board of Directors. The holders of Series B preferred stock, voting as a separate class, were entitled to elect three directors to the Board of Directors. The holders of common stock, voting as a separate class, were entitled to elect one director to the Board of Directors. All common and redeemable convertible preferred stockholders, voting together as a single class on an as-converted basis, were entitled to elect the balance of the total number of directors to the Board of Directors.

Dividends

The holders of the Series B preferred stock were entitled to receive non-cumulative dividends at an annual rate of 8% of the original issue price of $1.20 per share of the Series B preferred stock when and if declared by the Board of Directors and in preference to any dividends paid to the holders of any other class or series of redeemable convertible preferred stock or common stock. After payment of such Series B preferred stock dividend, the holders of Series A preferred stock were entitled to receive non-cumulative dividends at an annual rate of 8% of the original issue price of $1.00 per share of Series A preferred stock when and if declared by the Board of Directors and in preference to any dividends paid to the holders of common stock. After payment of such Series A preferred stock dividends and Series B preferred stock dividends, any additional dividends would be distributed among the holders of redeemable convertible preferred stock and common stock on a pro rata basis based upon the respective shares of common stock held by each holder (assuming conversion of all such redeemable convertible preferred stock into common stock). No dividends were declared during the years ended December 31, 2020 and 2019.

Equity Incentive Plan and Stock-Based Compensation Expense

12 Months Ended

Dec. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Equity Incentive Plan and Stock-Based Compensation Expense

9. Equity Incentive Plan and Stock-Based Compensation Expense

2020 Equity Incentive Plan

The Company adopted the 2020 Equity Incentive Plan (the 2020 Plan) in October 2020. The 2020 Plan is a successor to and continuation of the Amended and Restated 2016 Equity Incentive Plan (the 2016 Plan) and provides for the granting of stock options, stock appreciation rights, restricted stock, restricted stock units, and other stock or cash-based awards to individuals who are then employees, officers, directors or consultants. A total of 2,647,684 shares of common stock were approved to be initially reserved for issuance under the 2020 Plan. In addition, the number of shares of common stock available for issuance under the 2020 Plan will be automatically increased on the first day of each calendar year during the ten-year term of the 2020 Plan, beginning with January 1, 2021 and ending with January 1, 2030, by an amount equal to 5% of the outstanding number of shares of the Company’s common stock on December 31st of the preceding calendar year or such lesser amount as determined by the Company’s Board of Directors. Following the effectiveness of the 2020 Plan, no further grants will be made under the 2016 Plan; however, shares subject to awards granted under the 2016 Plan will continue to be governed by the 2016 Plan. Any shares subject to outstanding stock options or other stock awards that were granted under the 2016 Plan that terminate or expire prior to exercise or settlement; are settled in cash; are forfeited or repurchased because of the failure to vest; or are reacquired or withheld to satisfy a tax withholding obligation or the purchase or exercise price in accordance with the terms of the 2016 Plan will also be reserved for issuance under the 2020 Plan.

Under the Plan, the Board of Directors determines the per share exercise price of each stock option, which for ISOs shall not be less than 100% of the fair market value of a share on the date of grant; provided that the exercise price of an ISO granted to a stockholder who at the time of grant owns stock representing more than 10% of the voting power of all classes of stock (a 10% stockholder) shall not be less than 110% of the fair market value of a share on the date of grant.

The Board of Directors determines the period over which options vest and become exercisable. Options granted to new employees generally vest over a four-year period: 25% of the shares vest on the first anniversary from the vesting commencement date of the option and an additional 1/48th of the shares vest on each monthly anniversary thereafter, subject to the employee’s continuous service through each vesting date.

The Board of Directors also determines the term of options, provided the maximum term for ISOs granted to a 10% stockholder must be no longer than five years from date of grant and the maximum term for all other options must be no longer than ten years from date of grant. If an option holder’s service terminates, options generally terminate three months from the date of termination except under certain circumstances, such as death or disability.

Under the 2020 Plan and the 2016 Plan, individuals can be granted the ability to early exercise their options. There were no shares, related to the early exercise of options, subject to repurchase by the Company as of December 31, 2020.

A summary of the Company’s stock option activity and related information is as follows (in thousands, except share and per share amounts):

	Outstanding Stock Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
Balance as of December 31, 2018		430,354		$	0.89		8.4	$	123
Granted		485,150			1.43		—		—
Exercised		—			—		—		—
Forfeited/Cancelled		(56,182	)		0.85		—		—
Balance as of December 31, 2019		859,322			1.20		7.9		209
Granted		1,775,808			3.33		—		—
Exercised		(57,614	)		0.89		—		—
Forfeited/Cancelled		(298,745	)		1.86		—		—
Balance as of December 31, 2020		2,278,771		$	2.78		8.6	$	49,059
Vested and expected to vest as of December 31, 2020		2,132,726		$	2.76		8.5	$	45,965
Vested and exercisable as of December 31, 2020		603,963		$	1.42		6.2	$	13,822

Stock options vested and expected to vest differs from total stock options outstanding as it excludes performance-based stock options for which the performance criteria have not been achieved as of December 31, 2020. During 2020, the Company granted options to purchase 127,042 shares of common stock with performance criteria stipulating that no shares will vest unless certain financing and other related milestones are achieved. In January 2021, the Board of Directors determined that the performance-based vesting criteria of such options had been satisfied. Additionally, the Company granted an option to purchase 19,003 shares of common stock with the performance criteria stipulating that no shares will vest unless certain clinical development milestones are achieved. As of December 31, 2020, the option awardee had not yet achieved this performance criteria.

The aggregate intrinsic values of options outstanding and exercisable were calculated as the difference between the exercise price of the options and the estimated fair value of the Company’s common stock as of the respective balance sheet date. The total intrinsic value of options exercised was $0.3 million for the year ended December 31, 2020. There were no options exercised during the years ended December 31, 2019.

As of December 31, 2020, a total of 2,647,684 shares were authorized to be issued under the 2020 Plan and 2,637,076 shares remained available for issuance, and a total of 2,268,163 shares were authorized to be issued under the 2016 Plan and no shares remained available for issuance.

As of December 31, 2019, a total of 863,920 shares were authorized to be issued and 4,598 shares remained available for issuance under the 2016 Plan.

Stock Options Granted to Employees

The Company recognizes compensation expense for stock option awards granted to employees on a straight-line basis over the requisite service period of the award, generally four years. During the years ended December 31, 2020 and 2019, the Company granted options to purchase an aggregate of 1,775,808 and 427,055 shares of common stock to grantees with a weighted-average exercise price of $3.33 and $1.43 per share, respectively. For the years ended December 31, 2020 and 2019, the weighted-average fair value of options granted was $3.56 and $0.98 per share, respectively, and was estimated using the Black-Scholes option-pricing model, with the following weighted-average assumptions:

	2020			2019
Expected term (in years)		6.0			6.0
Expected volatility		80.1	%		80.0	%
Risk-free interest rate		0.4	%		1.8	%
Expected dividend rate		0.0	%		0.0	%

The total fair value of options that vested during the years ended December 31, 2020 and 2019 was $0.6 million and $0.1 million, respectively.

Stock Options Granted to Nonemployees

The Company recognizes compensation expense for stock option awards granted to nonemployees as the stock options are earned over the vesting period of the award. During the year ended December 31, 2019, the Company granted options to purchase an aggregate of 58,095 shares of common stock to nonemployees with a weighted-average exercise price of $1.44 per share. The Company did not grant any stock options to nonemployees during the year ended December 31, 2020.

2020 Employee Stock Purchase Plan

The Company’s Board of Directors adopted and the Company’s stockholders approved the 2020 Employee Stock Purchase Plan (the ESPP) in October 2020. The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation. At the end of each purchase period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock as of the offering date or the applicable purchase date. A total of 220,640 shares of common stock were approved to be initially reserved for issuance under the ESPP. In addition, the number of shares of common stock available for issuance under the ESPP will be automatically increased on the first day of each calendar year during the first ten-years of the term of the ESPP, beginning with January 1, 2021 and ending with January 1, 2030, by an amount equal to the lessor of (i) 1% of the outstanding number of shares of the Company’s common stock on December 31st of the preceding calendar year, (ii) 441,280 shares of common stock or (iii) such lesser amount as determined by the Board of Directors. As of December 31, 2020, 220,640 shares of common stock remained available for issuance under the ESPP.

Except for the initial offering period, the ESPP provides for 24-month offering periods starting every January 1^st and July 1^st, each consisting of four six-month purchase periods. The initial offering period runs from October 8, 2020 to December 31, 2022.

The Company recognizes compensation expense for its ESPP awards on a straight-line basis over the requisite service period for the entire award, typically two years. Total compensation expense related to the ESPP for the year ended December 31, 2020 was $32 thousand. The following range of assumptions were used to calculate stock-based compensation for each stock purchase right granted under the ESPP:

	2020	2019
Expected term (in years)	0.7 - 2.2		—
Expected volatility	89.2 - 93.0%		—
Risk-free interest rate	0.1 - 0.2%		—
Expected dividend rate	0.0%		—

Fair Value of Equity-Settled Awards

Prior to the IPO, the fair value of the Company’s common stock was determined by the Board of Directors since it was not publicly traded. The Board of Directors determined fair value of the common stock at the time of grant of the option by considering a number of objective and subjective factors including valuation of comparable companies, sales of redeemable convertible preferred stock to third parties, operating and financial performance, the lack of liquidity of capital stock, and general and industry specific economic outlook, amongst other factors. Following the IPO, the fair market value of the Company’s common stock is determined based on the closing price of its common stock on the Nasdaq Global Select Market.

Estimating the fair value of equity-settled awards as of the grant date using the Black-Scholes option pricing model is affected by assumptions regarding several complex variables. Changes in the assumptions can materially affect the fair value and ultimately how much stock-based compensation expense is recognized. These inputs are subjective and generally require significant analysis and judgment to develop. These inputs are as follows:

▪

Expected Term. The expected term for employees is based on the simplified method, as the Company’s stock options have the following characteristics: (i) granted at-the-money; (ii) exercisability is conditioned upon service through the vesting date; (iii) termination of service prior to vesting results in forfeiture; (iv) limited exercise period following termination of service; and (v) options are non-transferable and non-hedgeable, or “plain vanilla” options, and the Company has limited history of exercise data. The expected term for non-employees is based on the remaining contractual term.

▪

Expected Volatility. The expected volatility is estimated based on the historical volatilities for comparable publicly traded biopharmaceutical companies. In evaluating similarity, the Company considered factors such as market capitalization, stage of development, area of specialty, and stock-specific attributes. The Company will continue to analyze the historical stock price volatility and expected term assumptions as more historical data for the Company’s common stock becomes available.

▪

Risk-Free Interest Rate. The risk-free interest rate is based on U.S. Treasury constant maturity rates with remaining terms similar to the expected term of the options.

▪

Expected Dividend Rate. The Company has never paid any dividends and does not plan to pay dividends in the foreseeable future, and, therefore, used an expected dividend rate of zero in the valuation model.

▪

Forfeitures. The Company accounts for forfeitures as they occur.

Stock-Based Compensation Expense

The following table summarizes the components of stock-based compensation expense recognized in the Company’s statement of operations during the years ended December 31, 2020 and 2019 (in thousands):

	Year Ended December 31,
	2020		2019
Research and development	$	327	$	119
General and administrative		428		77
Total stock-based compensation expense	$	755	$	196

Unrecognized stock-based compensation expense as of December 31, 2020 was approximately $5.0 million, which is expected to be recognized over a weighted-average vesting term of 3.5 years.

License Agreement

12 Months Ended

Dec. 31, 2020

Research And Development [Abstract]

License Agreement

10. License Agreement

In May 2016, the Company entered into a license agreement (the License Agreement), with Eli Lilly and Company (Lilly). Pursuant to the terms of the License Agreement, Lilly granted the Company an exclusive, worldwide, royalty bearing, sublicensable license under certain technology, patent rights, know-how and proprietary materials related to certain compounds, to research, develop, and commercialize such compounds for all pharmaceutical uses.

As partial consideration for the rights granted to the Company under the License Agreement, the Company made a one-time upfront payment to Lilly of $0.8 million during the year ended December 31, 2016, which was recorded as research and development expense as there was no alternative use due to the early stage of the technology. The Company is also required to pay Lilly up to an aggregate of $23.0 million upon the achievement, during the time the License Agreement remains in effect, of certain milestones relating to the clinical development and commercial sales of products licensed under the License Agreement. Such payments are for predetermined fixed amounts, are paid only upon the first occurrence of each event, and are due shortly after achieving the applicable milestone. In addition, the Company is required to pay Lilly tiered royalties on annual worldwide net sales with rates ranging from mid-single-digits to sub-teens. No additional amounts were paid by the Company to Lilly during any of the periods presented, nor were due as of such dates pursuant to the License Agreement.

The License Agreement will remain in effect, unless earlier terminated, until the expiration of the royalty payment obligations. Royalties are payable on a product-by-product and country-by-country basis from the first commercial sale of the product until the later of (i) the tenth anniversary of the date of first commercial sale in such country, (ii) the expiration in such country of the last-to-expire licensed patent having a valid claim covering the manufacture, use or sale of the licensed product as commercialized in such country, and (iii) the expiration of any data or regulatory exclusivity period for the licensed product in such country.

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Income Taxes

11. Income Taxes

The Company has incurred cumulative domestic net operating losses (NOL) since inception and, consequently, has not recorded any income tax expense for the years ended December 31, 2020 and 2019 due to its net operating loss position.

The reconciliation of the federal statutory income tax rate to the Company’s effective tax rate is as follows:

	December 31,
	2020				2019
Federal statutory tax rate		21.00		%		21.00		%
State tax, net of federal benefit		6.98		%		—		%
Nondeductible expenses		(0.09	)	%		0.14		%
Tax credits		6.15		%		2.02		%
Change in valuation allowance		(41.38	)	%		(23.15	)	%
Prior year true-up for state net operating losses		6.96		%		—		%
Other		0.38		%		(0.01	)	%
Effective tax rate		0		%		0		%

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance. The net valuation allowance increased by approximately $12.2 million and $3.0 million during the years ended December 31, 2020 and 2019, respectively.

Significant components of the Company’s net deferred tax assets and liabilities are as follows (in thousands):

	December 31,
	2020			2019
Deferred tax assets:
Net operating loss carryforwards	$	16,381		$	6,259
Accruals		326			151
Intangible assets		143			119
Tax credits		2,500			682
Other		109			25
Total gross deferred tax assets		19,459			7,236
Valuation allowance for deferred tax assets		(19,459	)		(7,236	)
Total net deferred tax assets	$	—		$	—

As of December 31, 2020, the Company had federal net operating loss carryforwards of approximately $58.6 million and $58.4 million in state net operating loss carryforwards. If not utilized, the federal net operating loss carryforwards incurred before January 1, 2018 will begin to expire in 2036, and state net operating loss carryforwards will begin to expire in 2036. The federal net operating losses of $51.4 million incurred in 2018 and beyond do not expire.

Under Sections 382 and 383 of the Internal Revenue Code (IRC) of 1986, as amended (the Code), if a corporation undergoes an “ownership change,” the company’s ability to use its pre-change net operating loss carryforwards and other pre-change attributes, such as research tax credits, to offset its post-change income may be limited. In general, an “ownership change” will occur if there is a cumulative change in ownership by “5% shareholders” that exceeds 50 percentage points over a rolling three-year period. Tax credits are subject to IRC Section 383. In the event of a change in ownership as defined by this code section, the usage of the credits may be limited. Similar rules may apply under state tax laws. As of December 31, 2020, the Company determined that an ownership change occurred on May 2, 2016 and August 7, 2020. As a result of the ownership changes, the Company derecognized an immaterial amount of net operating loss-related deferred tax assets for federal and state purposes as of December 31, 2020. The ability of the Company to use its remaining net operating loss carryforwards is subject to Section 382 limitation and may be further limited if the Company experiences a Section 382 ownership change as a result of future changes in its stock ownership.

As of December 31, 2020, the Company had federal and state tax credit carryforwards of approximately $3.0 million and $0.6 million, respectively. If not utilized, the federal tax credits will begin to expire in 2036 and the state tax credits do not expire. As a result of the previously mentioned ownership changes, the Company has derecognized approximately $2 thousand of gross federal tax credit-related deferred tax assets due to the Section 383 limitation as of December 31, 2020. The Company has not derecognized any of the state tax credit-related deferred tax assets because the credits do not expire.

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 2020 tax provision.

On June 29, 2020, the California Governor signed Assembly Bill 85 (A.B. 85), which became California law, A.B. 85, which includes several tax measures, provided 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 $5.0 million of tax per year. Generally, A.B. 85 suspends the use of net operating losses for taxable years 2020, 2021 and 2022 for taxable income of $1.0 million or more. Since the Company is not expected to generate California source taxable income of more than $1.0 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 the CARES Act, while providing aid to business 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.

Uncertain Income Tax Positions

The Company accounts for uncertainty in income taxes in accordance with ASC 740. Tax positions are evaluated in a two-step process, whereby the Company first determines whether it is more likely than not that a tax position will be sustained upon examination by tax authorities, including resolutions of any related appeals or litigation processes, based on technical merit. If a tax position meets the more-likely-than-not recognition threshold, it is then measured to determine the amount of benefit to be recognized in the financial statements. The tax position is measured as the largest amount of benefit that is greater than 50% likely of being realized upon ultimate settlement.

The Company does not expect the amount of unrecognized tax benefits to materially change in the next 12 months.

The Company had approximately $1.1 million and $0.4 million of unrecognized tax benefits as of December 31, 2020 and 2019, respectively. As the Company has a full valuation allowance on its deferred tax assets, the unrecognized tax benefits have reduced the net deferred tax assets and the valuation allowance in the same amount.

A reconciliation of the beginning and ending balance of the unrecognized tax benefits is as follows (in thousands):

	December 31,
	2020		2019
Balance at the beginning of the year	$	398	$	230
Increase of unrecognized tax benefits taken in prior years		10		—
Increase of unrecognized tax benefits related to current year		686		168
Balance at the end of the year	$	1,094	$	398

Interest and penalty related to unrecognized tax benefits would be included as income tax expense in the Company’s statements of operations. As of December 31, 2020 and 2019, the Company had not recognized any tax-related penalties or interest in its financial statements.

The Company files income tax returns in the U.S. federal jurisdiction and California state jurisdiction. The Company is not currently under audit by the Internal Revenue Service or any other similar state, local, or foreign authority. All tax years remain open to examination by major taxing jurisdictions to which the Company is subject.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

401(k) Retirement Savings Plan

12 Months Ended

Dec. 31, 2020

Compensation And Retirement Disclosure [Abstract]

401(k) Retirement Savings Plan

12. 401(k) Retirement Savings Plan

In December 2017, the Company adopted a 401(k) plan (the 401(k) Plan) for all employees who have met certain eligibility requirements. Under the agreement, employees may elect to contribute a portion of their eligible compensation, subject to certain limitations. The Company did not make any matching employer contributions to the 401(k) Plan as of and for the years ended December 31, 2020 and 2019.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
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+ Details

Net Loss Per Share

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Net Loss Per Share

13. Net Loss Per Share

The following table sets forth the computation of the basic and diluted net loss per share (in thousands, except share and per share amounts):

	Year Ended December 31,
	2020			2019
Numerator:
Net loss	$	(29,539	)	$	(13,088	)
Denominator:
Weighted-average common shares outstanding		5,991,213			764,408
Net loss per share, basic and diluted	$	(4.93	)	$	(17.12	)

Basic net loss per share was the same as diluted net loss per share for all periods as the inclusion of potentially dilutive securities would have been anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations were as follows:

	December 31,
	2020		2019
Series A redeemable convertible preferred stock (on an if-converted basis)		—		4,280,690
Shares subject to outstanding common stock options		2,278,771		859,322
Estimated shares issuable under the employee stock purchase plan		24,118		—
Shares subject to common stock warrants		—		49,609
Total		2,302,889		5,189,621

Subsequent Events

12 Months Ended

Dec. 31, 2020

Subsequent Events [Abstract]

Subsequent Events

14. Subsequent Events

Stock Option Grants and Modification

In January 2021, the Company granted options to purchase an aggregate of 351,000 shares of common stock to employees pursuant to the 2020 Plan.

During 2020, the Company granted options to certain executive officers to purchase 127,042 shares of common stock with performance criteria stipulating that no shares will vest unless certain financing and other related milestones are achieved. In January 2021, the Board of Directors determined that the performance-based vesting criteria of such options had been satisfied, which was deemed as a modification.

First Amendment to Loan and Security Agreement

In March 2021, the Company and SVB entered into a First Amendment to Loan and Security Agreement (the First Amendment), pursuant to which the Company and SVB amended the Loan Agreement. The First Amendment increases the aggregate principal amount of the Term Loan commitment by SVB to up to $30.0 million dollars. Up to $20.0 million is available under the first tranche of the Term Loan (the First Tranche), $5.0 million of which was advanced immediately to repay the outstanding obligations under the Term Loan prior to the First Amendment with the remainder of the First Tranche commitments available through December 31, 2021, and up to $10.0 million is available under the second tranche (the Second Tranche) subject to the completion of certain clinical and financial milestones which Second Tranche commitment is available through December 31, 2022. Pursuant to the First Amendment, the Term Loan will mature on January 1, 2026.

Pursuant to the First Amendment, the Company is required to make monthly payments of interest only commencing on the first day of the month following the funding date of each respective tranche and continuing thereafter through December 31, 2022 to the extent that the Company does not borrow any part of the Second Tranche or December 31, 2023 if the Company has borrowed some or all of the Second Tranche. Outstanding principal balances under the Term Loan, as amended by the First Amendment, bear interest at a floating per annum rate equal to (A) if the Company does not borrow under the Second Tranche, the greater of (x) 1% above the prime rate or (y) 4.25%; or (B) if the Company does borrow under the Second Tranche, the greater of (x) 3% above the prime rate or (y) 6.25%.

Following the interest-only period, the outstanding Term Loan balance will be payable in (i) 37 consecutive monthly payments (or 25 if the Company borrows under the Second Tranche) after the end of the Amendment Interest-Only Period and continuing on the same day of each month thereafter, in amounts that would fully amortize such Term Loan balance, as of the first business day of the first month following the interest-only period, over the repayment period, plus (ii) monthly payments of accrued but unpaid interest. The final payment due on the maturity date shall include all outstanding principal and all accrued unpaid interest and an End of Term Payment totaling (x) 6% of the original funded principal amount of the First Tranche if the Company does not borrow under the Second Tranche, or (y) 9.5% of the total original funded principal amount under the First and Second Tranche if the Company does borrow under the Second Tranche. The Company may prepay amounts outstanding under the Term Loan at any time provided certain notification conditions are met, in which case, all outstanding principal plus accrued and unpaid interest, the End of Term Payment, a prepayment fee between 1% and 3% of the commitment amount of the First and Second Tranches, and any bank expenses become due and payable.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Basis of Presentation

Use of Estimates

Risks and Uncertainties

Segment Reporting

Cash and Cash Equivalents

Restricted Cash

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed statements of cash flows (in thousands):

	December 31,
	2020		2019
Cash and cash equivalents	$	157,150	$	3,924
Restricted cash		216		—
Total cash, cash equivalents and restricted cash	$	157,366	$	3,924

Fair Value of Financial Instruments

The Company determined the fair value of financial assets and liabilities using the fair value hierarchy that describes three levels of inputs that may be used to measure fair value, as follows:

▪

Level 1—Quoted prices in active markets for identical assets and liabilities;

▪

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

Concentration of Credit Risk

Leases

The Company adopted Accounting Standards Update (ASU), No. 2016-02, Leases (Topic 842) effective January 1, 2020.

Redeemable Convertible Preferred Stock

Research and Development Expenses

Accrued Research and Development Expenses

Patent Costs

Income Taxes

Stock-Based Compensation

Net Loss per Share

Commitments and Contingencies

Emerging Growth Company Status

Recent Accounting Pronouncements Not Yet Adopted

Recently Adopted Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the condensed statements of cash flows (in thousands):

	December 31,
	2020		2019
Cash and cash equivalents	$	157,150	$	3,924
Restricted cash		216		—
Total cash, cash equivalents and restricted cash	$	157,366	$	3,924

Balance Sheet Components (Tables)

12 Months Ended

Dec. 31, 2020

Balance Sheet Components Disclosure [Abstract]

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):

	December 31,
	2020		2019
Accrued research and development expenses	$	2,002	$	265
Accrued general and administrative expenses		245		—
Lease liability, current portion		249		—
Total accrued expenses and other current liabilities	$	2,496	$	265

Leases (Tables)

12 Months Ended

Dec. 31, 2020

Leases [Abstract]

Future Minimum Annual Lease Commitments under Non-cancelable Operating Leases

Future minimum annual lease commitments under the Company’s non-cancelable operating leases as of December 31, 2020 were as follows (in thousands):

	Amount
2021	$	377
2022		464
2023		478
2024		493
2025		464
Total undiscounted future minimum lease payments		2,276
Less: present value discount		(374	)
Total discounted future minimum lease payments	$	1,902
Lease liability, current portion (included in "accrued expenses and other current liabilities" on the condensed balance sheet)	$	249
Lease liability, net of current portion		1,653
Total operating lease liability	$	1,902

Term Loan (Tables)

12 Months Ended

Dec. 31, 2020

Debt Disclosure [Abstract]

Schedule of Term Loan

The Term Loan and unamortized discount and debt issuance costs balances as of December 31, 2020 are shown below (in thousands):

	December 31, 2020
Total Term Loan debt	$	4,500
Less: unamortized discount and debt issuance costs		(24	)
Total Term Loan, net		4,476
Less: Term Loan, current portion		(2,554	)
Term loan, net of current portion	$	1,922

Schedule of Future Principal Payments

As of December 31, 2020, future principal payments per year under the Term Loan were as follows (in thousands):

	Amount
2021		2,571
2022		1,929
Total	$	4,500

Capital Structure (Tables)

12 Months Ended

Dec. 31, 2020

Equity [Abstract]

Summary of Common Stock Reserved for Future Issuance

Common stock reserved for future issuance, on an as converted basis, consisted of the following:

	December 31,
	2020		2019
Series A redeemable convertible preferred stock		—		4,280,690
Stock options, issued and outstanding		2,278,771		859,322
Stock options, available for future issuance		2,637,076		4,598
Employee stock purchase plan, available for future issuance		220,640		—
Common stock warrant		—		49,609
Total shares reserved		5,136,487		5,194,219

Schedule of Issued and Outstanding Redeemable Convertible Preferred Stock

As of December 31, 2019

Series

Authorized

Issued and

Outstanding

Original

Issue Price

Per Share

Aggregate

Liquidation

Amount

Net

Carrying

Value

Series A redeemable convertible preferred stock

28,000,000

1.0000

28,000

27,813

Equity Incentive Plan and Stock-Based Compensation Expense (Tables)

12 Months Ended

Dec. 31, 2020

Summary of Stock Option Activity

A summary of the Company’s stock option activity and related information is as follows (in thousands, except share and per share amounts):

	Outstanding Stock Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
Balance as of December 31, 2018		430,354		$	0.89		8.4	$	123
Granted		485,150			1.43		—		—
Exercised		—			—		—		—
Forfeited/Cancelled		(56,182	)		0.85		—		—
Balance as of December 31, 2019		859,322			1.20		7.9		209
Granted		1,775,808			3.33		—		—
Exercised		(57,614	)		0.89		—		—
Forfeited/Cancelled		(298,745	)		1.86		—		—
Balance as of December 31, 2020		2,278,771		$	2.78		8.6	$	49,059
Vested and expected to vest as of December 31, 2020		2,132,726		$	2.76		8.5	$	45,965
Vested and exercisable as of December 31, 2020		603,963		$	1.42		6.2	$	13,822

Schedule of Weighted-Average Assumptions to Estimate Fair Value Using Black-Scholes Option-Pricing Model

the following weighted-average assumptions:

	2020			2019
Expected term (in years)		6.0			6.0
Expected volatility		80.1	%		80.0	%
Risk-free interest rate		0.4	%		1.8	%
Expected dividend rate		0.0	%		0.0	%

Summary of Stock-Based Compensation Expense

	Year Ended December 31,
	2020		2019
Research and development	$	327	$	119
General and administrative		428		77
Total stock-based compensation expense	$	755	$	196

2020 Employee Stock Purchase Plan

Schedule of Range of Assumptions Used to Calculate Stock Based Compensation Each Stock Purchase Right Granted Under ESPP

The following range of assumptions were used to calculate stock-based compensation for each stock purchase right granted under the ESPP:

	2020	2019
Expected term (in years)	0.7 - 2.2		—
Expected volatility	89.2 - 93.0%		—
Risk-free interest rate	0.1 - 0.2%		—
Expected dividend rate	0.0%		—

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Abstract]

Schedule of Reconciliation of the Federal Statutory Income Tax Rate to Effective Tax Rate

The reconciliation of the federal statutory income tax rate to the Company’s effective tax rate is as follows:

	December 31,
	2020				2019
Federal statutory tax rate		21.00		%		21.00		%
State tax, net of federal benefit		6.98		%		—		%
Nondeductible expenses		(0.09	)	%		0.14		%
Tax credits		6.15		%		2.02		%
Change in valuation allowance		(41.38	)	%		(23.15	)	%
Prior year true-up for state net operating losses		6.96		%		—		%
Other		0.38		%		(0.01	)	%
Effective tax rate		0		%		0		%

Schedule of Significant Components of Net Deferred Tax Assets and Liabilities

Significant components of the Company’s net deferred tax assets and liabilities are as follows (in thousands):

	December 31,
	2020			2019
Deferred tax assets:
Net operating loss carryforwards	$	16,381		$	6,259
Accruals		326			151
Intangible assets		143			119
Tax credits		2,500			682
Other		109			25
Total gross deferred tax assets		19,459			7,236
Valuation allowance for deferred tax assets		(19,459	)		(7,236	)
Total net deferred tax assets	$	—		$	—

Schedule of Reconciliation of Beginning and Ending Balance of Unrecognized Tax Benefits

A reconciliation of the beginning and ending balance of the unrecognized tax benefits is as follows (in thousands):

	December 31,
	2020		2019
Balance at the beginning of the year	$	398	$	230
Increase of unrecognized tax benefits taken in prior years		10		—
Increase of unrecognized tax benefits related to current year		686		168
Balance at the end of the year	$	1,094	$	398

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Net Loss Per Share

The following table sets forth the computation of the basic and diluted net loss per share (in thousands, except share and per share amounts):

	Year Ended December 31,
	2020			2019
Numerator:
Net loss	$	(29,539	)	$	(13,088	)
Denominator:
Weighted-average common shares outstanding		5,991,213			764,408
Net loss per share, basic and diluted	$	(4.93	)	$	(17.12	)

Schedule of Potentially Dilutive Securities not Included in Calculation of Diluted Per Share

	December 31,
	2020		2019
Series A redeemable convertible preferred stock (on an if-converted basis)		—		4,280,690
Shares subject to outstanding common stock options		2,278,771		859,322
Estimated shares issuable under the employee stock purchase plan		24,118		—
Shares subject to common stock warrants		—		49,609
Total		2,302,889		5,189,621

Organization and Principal Activities - Additional Information (Details) $ / shares in Units, $ in Thousands			1 Months Ended	12 Months Ended
	Aug. 31, 2020 USD ($) shares	Feb. 29, 2020 USD ($) shares	Oct. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)
Organization And Principal Activities [Line Items]
Common stock, stock split ratio			0.153
Common stock, reverse stock split				1-for-6.541 basis
Cash and cash equivalents				$ 157,150	$ 3,924
Net loss				(29,539)	(13,088)
Cash in operations				27,500
Accumulated deficit				$ (60,841)	$ (31,302)
Redeemable Convertible Preferred Stock
Organization And Principal Activities [Line Items]
Redeemable convertible preferred stock converted into common stock \| shares			15,492,019	15,492,019
Series B Redeemable Convertible Preferred Stock
Organization And Principal Activities [Line Items]
Redeemable convertible preferred stock, shares issued \| shares	36,666,665	36,666,665		73,333,330
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs	$ 44,000	$ 43,600		$ 87,633
Initial Public Offering
Organization And Principal Activities [Line Items]
Offering price \| $ / shares			$ 15.00
Net proceeds of common stock			$ 93,400
Initial Public Offering \| Common Stock
Organization And Principal Activities [Line Items]
Initial public offering of common stock, net of underwriting expenses and offering costs, Shares \| shares			6,900,000	6,900,000
Overallotment Option \| Common Stock
Organization And Principal Activities [Line Items]
Initial public offering of common stock, net of underwriting expenses and offering costs, Shares \| shares			900,000

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2020 USD ($) Segment shares	Oct. 31, 2020 shares
Summary Of Significant Accounting Policies [Line Items]
Number of operating segment \| Segment	1
Interest or penalties charged related to unrecognized tax benefits	$ 0
Recognition of stock option awards over requisite service period	4 years
Right-of-use asset	$ 1,900,000
Lease liability	$ 1,902,000
Topic 842
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect	true
Topic 820
Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, accounting standards update, adopted	true
Change in accounting principle, accounting standards update, adoption date	Jan. 01, 2020
Change in accounting principle, accounting standards update, immaterial effect	true
Stock Option
Summary Of Significant Accounting Policies [Line Items]
Recognition of stock option awards over requisite service period	4 years
Redeemable Convertible Preferred Stock
Summary Of Significant Accounting Policies [Line Items]
Redeemable convertible preferred stock converted into common stock \| shares	15,492,019	15,492,019

Summary of Significant Accounting Policies - Schedule of Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Cash and cash equivalents	$ 157,150	$ 3,924
Restricted cash	216
Total cash, cash equivalents and restricted cash	$ 157,366	$ 3,924

Fair Value Measurements - Additional Information (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Estimated fair value of term loan	$ 4,800,000
Fair Value Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial assets fair value	0	$ 0
Liabilities fair value	0	0
Fair Value Non-recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial assets fair value	0	0
Liabilities fair value	$ 0	$ 0

Balance Sheet Components - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet Components Disclosure [Abstract]
Accrued research and development expenses	$ 2,002	$ 265
Accrued general and administrative expenses	245
Lease liability, current portion	249
Total accrued expenses and other current liabilities	$ 2,496	$ 265

Leases - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Feb. 29, 2020	Feb. 28, 2019	Dec. 31, 2020	Dec. 31, 2019
Leases [Abstract]
Operating lease commencement date	2020-09
Operating lease term	63 months	12 months
Operating leases, gross commitment	$ 2,300
Operating Leases, option to renew lease term description			The lease includes an option to renew the lease term for an additional period of 60 months. The renewal option is not included in the lease term or minimum lease payments disclosures below as the Company is not reasonably certain to exercise the option.
Operating Leases, option to renew lease term	true
Operating leases, renew lease term	60 months
Operating leases, lease expense			$ 100
Operating lease commencement date		2019-03
Short-term lease gross commitments		$ 200
Short-term lease extended term	3 months
Short term lease additional commitments	$ 42
Short term lease terminated			2020-05
Short-term lease expense			$ 100
Rent expense				$ 100
Weighted-average remaining lease term for operating leases			4 years 10 months 24 days
weighted-average discount rate			7.00%
Cash paid for amounts included in measurement of lease liabilities			$ 37

Leases - Future Minimum Annual Lease Commitments under Non-cancelable Operating Leases (Detail) $ in Thousands	Dec. 31, 2020 USD ($)
Leases [Abstract]
2021	$ 377
2022	464
2023	478
2024	493
2025	464
Total undiscounted future minimum lease payments	2,276
Less: present value discount	(374)
Total discounted future minimum lease payments	1,902
Lease liability, current portion (included in "accrued expenses and other current liabilities" on the condensed balance sheet)	$ 249
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	sprb:AccruedLiabilitiesAndOtherLiabilitiesCurrent
Lease liability, net of current portion	$ 1,653

Term Loan - Additional Information (Details)	1 Months Ended				12 Months Ended
Term Loan - Additional Information (Details)	Nov. 30, 2020 shares	Apr. 30, 2020 USD ($) Installment	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($) Tranche $ / shares shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Outstanding term loan, after unamortized discount and debt issuance costs					$ 4,476,000
Proceeds from issuance of term loan						$ 4,492,000
Net exercised of common stock \| shares					46,358
Term Loan \| Silicon Valley Bank
Debt Instrument [Line Items]
Debt instrument, extended term		6 months
Outstanding term loan, after unamortized discount and debt issuance costs				$ 4,500,000
Number of tranches \| Tranche				2
Principal payments commencement month and year		2021-01
Debt instrument, maturity		2022-09
Floating interest rate				4.25%
Number of Monthly Installments \| Installment		21
Frequency of payments					monthly
Principal payments commencement date		Jan. 01, 2021
End of term payment, percentage		6.00%
End of term payment, amount		$ 300,000
Debt issuance costs					$ 8,000
Unamortized debt issuance costs and debt discount					24,000
Interest payments on debt					$ 200,000
Term Loan \| Silicon Valley Bank \| Warrant
Debt Instrument [Line Items]
Number of shares issuable upon the exercise of warrant \| shares				49,609
Warrants exercise price \| $ / shares				$ 1.44
Estimated fair value of the warrant				$ 100,000
Term Loan \| Silicon Valley Bank \| Common Stock \| Warrant
Debt Instrument [Line Items]
Net exercised of common stock \| shares	46,358
Term Loan \| Silicon Valley Bank \| Minimum
Debt Instrument [Line Items]
Debt instrument prepayment fee percentage				1.00%
Term Loan \| Silicon Valley Bank \| Maximum
Debt Instrument [Line Items]
Debt instrument prepayment fee percentage				3.00%
Term Loan \| Silicon Valley Bank \| Prime Rate
Debt Instrument [Line Items]
Basis spread reduction for variable rate				1.00%
First Tranche Term Loan \| Silicon Valley Bank
Debt Instrument [Line Items]
Proceeds from issuance of term loan				$ 2,500,000
Second Tranche Term Loan \| Silicon Valley Bank
Debt Instrument [Line Items]
Outstanding term loan, after unamortized discount and debt issuance costs				$ 2,000,000
Proceeds from issuance of term loan			$ 2,000,000

Term Loan - Schedule of Term Loan (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Disclosure [Abstract]
Total Term Loan debt	$ 4,500
Less: unamortized discount and debt issuance costs	(24)
Total Term Loan, net	4,476
Less: Term Loan, current portion	(2,554)	$ (1,252)
Term loan, net of current portion	$ 1,922	$ 3,193

Term Loan - Schedule of Future Principal Payments (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Debt Disclosure [Abstract]
2021	$ 2,571
2022	1,929
Total	$ 4,500

Capital Structure - Additional Information (Details)			12 Months Ended
Capital Structure - Additional Information (Details)	Aug. 31, 2020 USD ($) shares	Feb. 29, 2020 USD ($) shares	Dec. 31, 2020 USD ($) Director $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Oct. 31, 2020 shares	Dec. 31, 2018 shares
Class Of Stock [Line Items]
Common stock shares authorized \| shares			200,000,000	41,000,000
Common stock par value			$ 0.0001	$ 0.0001
Common stockholders voting rights			one vote
Common stock dividends declared \| $			$ 0
Conversion basis description			Additionally, each share of redeemable convertible preferred stock would be automatically converted into common stock (i) immediately prior to the closing of the Company’s sale of its common stock in a firm commitment underwritten public offering pursuant to a registration statement under the Securities Act of 1933, as amended, in which (a) the gross cash proceeds to the Corporation (before underwriting discounts, commissions and fees) were at least $50.0 million, (b) the price per share in the public offering was at least $15.6984 per share, and (c) the Company’s shares were listed for trading on the New York Stock Exchange, Nasdaq Global Select Market or Nasdaq Global Market, or (ii) upon the affirmative election of the holders of a majority shares of then-outstanding shares of redeemable convertible preferred stock, voting together as a single class on an as-converted basis, which majority must include the approval of certain holders of Series B preferred stock.
Potential minimum gross cash proceeds from redeemable convertible preferred stock \| $			$ 50,000,000
Potential minimum public offering price per share			$ 15.6984
Redeemable convertible preferred stock holders, voting rights			one vote
Dividends declared \| $			$ 0	$ 0
Common Stock
Class Of Stock [Line Items]
Number of directors entitled to be elected \| Director			1
Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Redeemable convertible preferred stock converted into common stock \| shares			15,492,019		15,492,019
Redeemable convertible preferred stock, shares outstanding \| shares			0
Series B Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized \| shares			73,333,330
Redeemable convertible preferred stock, shares issued \| shares	36,666,665	36,666,665	73,333,330
Issue price per share			$ 1.20
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs \| $	$ 44,000,000	$ 43,600,000	$ 87,633,000
Liquidation preference original issuance price per share			$ 1.20
Series A Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Redeemable convertible preferred stock, shares outstanding \| shares			0	28,000,000		20,000,000
Redeemable convertible preferred stock, shares authorized \| shares			0	28,000,000
Redeemable convertible preferred stock, shares issued \| shares			0	28,000,000
Issue price per share				$ 1.0000
Proceeds from issuance of redeemable convertible preferred stock, net of issuance costs \| $				$ 7,941,000
Liquidation preference original issuance price per share			$ 1.00
Series A Preferred Stock
Class Of Stock [Line Items]
Liquidation preference original issuance price per share			1.00
Redeemable convertible preferred stockholders entitled to receive greater of maximum participation price per share			4.00
Conversion price per share			$ 6.541
Number of directors entitled to be elected \| Director			2
Non-cumulative dividends entitled to receive by redeemable preferred stock holders			8.00%
Series B Preferred Stock
Class Of Stock [Line Items]
Liquidation preference original issuance price per share			$ 1.20
Redeemable convertible preferred stockholders entitled to receive greater of maximum participation price per share			4.80
Conversion price per share			$ 7.849
Number of directors entitled to be elected \| Director			3
Non-cumulative dividends entitled to receive by redeemable preferred stock holders			8.00%

Capital Structure - Summary of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2020	Dec. 31, 2019
Class Of Stock [Line Items]
Shares reserved for future issuance	5,136,487	5,194,219
Employee Stock Purchase Plan, Available for Future Issuance
Class Of Stock [Line Items]
Shares reserved for future issuance	220,640	0
Stock Options, Issued and Outstanding
Class Of Stock [Line Items]
Shares reserved for future issuance	2,278,771	859,322
Stock Options, Available for Future Issuance
Class Of Stock [Line Items]
Shares reserved for future issuance	2,637,076	4,598
Series A Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Shares reserved for future issuance		4,280,690
Common Stock Warrant
Class Of Stock [Line Items]
Shares reserved for future issuance		49,609

Capital Structure - Schedule of Issued and Outstanding Redeemable Convertible Preferred Stock (Details) - Series A Redeemable Convertible Preferred Stock - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Temporary Equity [Line Items]
Shares Authorized	0	28,000,000
Shares Issued	0	28,000,000
Shares Outstanding	0	28,000,000	20,000,000
Original Issue Price Per Share		$ 1.0000
Aggregate Liquidation Amount	$ 0	$ 28,000
Net Carrying Value		$ 27,813	$ 19,872

Equity Incentive Plan and Stock-Based Compensation Expense - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Jan. 31, 2021	Oct. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for future issuance			5,136,487	5,194,219
Equity incentive plans terms			Following the effectiveness of the 2020 Plan, no further grants will be made under the 2016 Plan; however, shares subject to awards granted under the 2016 Plan will continue to be governed by the 2016 Plan. Any shares subject to outstanding stock options or other stock awards that were granted under the 2016 Plan that terminate or expire prior to exercise or settlement; are settled in cash; are forfeited or repurchased because of the failure to vest; or are reacquired or withheld to satisfy a tax withholding obligation or the purchase or exercise price in accordance with the terms of the 2016 Plan will also be reserved for issuance under the 2020 Plan.
Number of shares early exercised under any plan			0
Aggregate intrinsic value of options exercised			$ 300
Requisite service period of award			4 years
Options granted to purchase shares of common stock			1,775,808	427,055
Options granted to purchase shares of common stock, weighted-average exercise price			$ 3.33	$ 1.43
Weighted-average fair value of options granted			$ 3.56	$ 0.98
Total fair value of options vested			$ 600	$ 100
Compensation expense			755	$ 196
Unrecognized stock-based compensation expense			$ 5,000
Unrecognized stock-based compensation expense expected to be recognized over weighted-average vesting term			3 years 6 months
Stock Options Granted to Nonemployees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted to purchase shares of common stock			0	58,095
Options granted to purchase shares of common stock, weighted-average exercise price				$ 1.44
Performance Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted to purchase shares of common stock			127,042
Performance Stock Options \| Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted to purchase shares of common stock	19,003
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for future issuance		2,647,684
Term of automatically increase in common stock available for issuance		10 years
Percentage of outstanding shares subject to automatic increase in common stock		5.00%
Equity incentive plans terms		In addition, the number of shares of common stock available for issuance under the 2020 Plan will be automatically increased on the first day of each calendar year during the ten-year term of the 2020 Plan, beginning with January 1, 2021 and ending with January 1, 2030, by an amount equal to 5% of the outstanding number of shares of the Company’s common stock on December 31st of the preceding calendar year or such lesser amount as determined by the Company’s Board of Directors.
Incentive stock options granted description			Under the Plan, the Board of Directors determines the per share exercise price of each stock option, which for ISOs shall not be less than 100% of the fair market value of a share on the date of grant; provided that the exercise price of an ISO granted to a stockholder who at the time of grant owns stock representing more than 10% of the voting power of all classes of stock (a 10% stockholder) shall not be less than 110% of the fair market value of a share on the date of grant.
Vesting period			4 years
Equity incentive plan, maximum term			5 years
Options termination term, if option holders service terminate			3 months
Options granted to purchase shares of common stock			1,775,808	485,150
Number of options exercised			57,614	0
Shares authorized for issuance			2,647,684
Shares remained available for issuance			2,637,076
Options granted to purchase shares of common stock, weighted-average exercise price			$ 3.33	$ 1.43
2020 Equity Incentive Plan \| Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted to purchase shares of common stock	351,000
2020 Equity Incentive Plan \| All Other Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Equity incentive plan, maximum term			10 years
2020 Equity Incentive Plan \| First Anniversary
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage			25.00%
2020 Equity Incentive Plan \| Monthly Anniversary
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage			2.083%
2020 Equity Incentive Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of incentive stock options granted			100.00%
Percentage of Exercise price of incentive stock options granted owns stock			10.00%
Fair market value exercise price percentage			110.00%
2016 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares authorized for issuance			2,268,163	863,920
Shares remained available for issuance			0	4,598
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for future issuance		220,640
Term of automatically increase in common stock available for issuance		10 years
Percentage of outstanding shares subject to automatic increase in common stock		1.00%
Equity incentive plans terms			In addition, the number of shares of common stock available for issuance under the ESPP will be automatically increased on the first day of each calendar year during the first ten-years of the term of the ESPP, beginning with January 1, 2021 and ending with January 1, 2030, by an amount equal to the lessor of (i) 1% of the outstanding number of shares of the Company’s common stock on December 31st of the preceding calendar year, (ii) 441,280 shares of common stock or (iii) such lesser amount as determined by the Board of Directors.
Shares remained available for issuance		441,280	220,640
Requisite service period of award			2 years
Maximum percentage of compensation that an employee is allowed to purchase shares		15.00%
Purchase price of common stock expressed as a percentage of fair market value		85.00%
Employee stock purchase plan offering period			provides for 24-month offering periods starting every January 1st and July 1st, each consisting of four six-month purchase periods
Initial offering period			October 8, 2020 to December 31, 2022.
Compensation expense			$ 32

Equity Incentive Plan and Stock-Based Compensation Expense - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Granted, Weighted-Average Exercise Price	$ 3.33	$ 1.43
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Beginning Balance, Outstanding Stock Options	859,322	430,354
Granted, Outstanding Stock Options	1,775,808	485,150
Exercised, Outstanding Stock Options	(57,614)	0
Forfeited/Cancelled, Outstanding Stock Options	(298,745)	(56,182)
Ending Balance, Outstanding Stock Options	2,278,771	859,322	430,354
Vested and expected to vest, Outstanding Stock Options	2,132,726
Vested and exercisable, Outstanding Stock Options	603,963
Beginning Balance, Weighted-Average Exercise Price	$ 1.20	$ 0.89
Granted, Weighted-Average Exercise Price	3.33	1.43
Exercised, Weighted-Average Exercise Price	0.89
Forfeited/Cancelled, Weighted-Average Exercise Price	1.86	0.85
Ending Balance, Weighted-Average Exercise Price	2.78	$ 1.20	$ 0.89
Vested and expected to vest, Weighted-Average Exercise Price	2.76
Vested and exercisable, Weighted-Average Exercise Price	$ 1.42
Weighted-Average Remaining Contractual Life (Years)	8 years 7 months 6 days	7 years 10 months 24 days	8 years 4 months 24 days
Vested and expected to vest, Weighted-Average Remaining Contractual Life (Years)	8 years 6 months
Vested and exercisable, Weighted-Average Remaining Contractual Life (Years)	6 years 2 months 12 days
Aggregate Intrinsic Value	$ 49,059	$ 209	$ 123
Vested and expected to vest, Aggregate Intrinsic Value	45,965
Vested and exercisable, Aggregate Intrinsic Value	$ 13,822

Equity Incentive Plan and Stock-Based Compensation Expense - Schedule of Weighted-Average Assumptions to Estimate Fair Value Using Black-Scholes Option-Pricing Model (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected term (in years)	6 years	6 years
Expected volatility	80.10%	80.00%
Risk-free interest rate	0.40%	1.80%
Expected dividend rate	0.00%	0.00%

Equity Incentive Plan and Stock-Based Compensation Expense - Schedule of Range of Assumptions Used to Calculate Stock Based Compensation Each Stock Purchase Right Granted Under ESPP (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	6 years	6 years
Expected volatility	80.10%	80.00%
Risk-free interest rate	0.40%	1.80%
Expected dividend rate	0.00%	0.00%
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)		0 years
Expected dividend rate	0.00%
2020 Employee Stock Purchase Plan \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	8 months 12 days
Expected volatility	89.20%
Risk-free interest rate	0.10%
2020 Employee Stock Purchase Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)	2 years 2 months 12 days
Expected volatility	93.00%
Risk-free interest rate	0.20%

Equity Incentive Plan and Stock-Based Compensation Expense - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 755	$ 196
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	327	119
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 428	$ 77

License Agreement - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2016
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense	$ 23,854,000	$ 10,817,000
License Agreement \| Eli Lilly and Company
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development expense			$ 800,000
Milestone payments due	23,000,000
Research and development arrangement, costs incurred	$ 0	$ 0

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Jun. 29, 2020	Dec. 31, 2018
Income Tax Disclosure [Line Items]
Income tax expense	$ 0	$ 0
Increase in net valuation allowance	12,200,000	3,000,000
Unrecognized tax benefits	1,094,000	398,000		$ 230,000
Income tax penalties or interest	$ 0	$ 0
Maximum
Income Tax Disclosure [Line Items]
Tax credit carryforward, amount			$ 5,000,000
Percentage of tax positions likely of being realized upon ultimate settlement	50.00%
Minimum \| Tax Year 2020
Income Tax Disclosure [Line Items]
Suspension of net operating loss carryforwards on taxable income			1,000,000
Minimum \| Tax Year 2021
Income Tax Disclosure [Line Items]
Suspension of net operating loss carryforwards on taxable income			1,000,000
Minimum \| Tax Year 2022
Income Tax Disclosure [Line Items]
Suspension of net operating loss carryforwards on taxable income			$ 1,000,000
Federal
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 58,600,000			$ 51,400,000
Net operating loss carryforwards expiration year	2036
Federal \| Research Credit Carry Forwards
Income Tax Disclosure [Line Items]
Tax credit carryforward, amount	$ 3,000,000
Tax credit carryforward expiration year	2036
Gross federal tax credit-related deferred tax assets derecognized	$ 2,000
State
Income Tax Disclosure [Line Items]
Net operating loss carryforwards	$ 58,400,000
Net operating loss carryforwards expiration year	2036
State \| Research Credit Carry Forwards
Income Tax Disclosure [Line Items]
Tax credit carryforward, amount	$ 600,000

Income Taxes - Schedule of Reconciliation of the Federal Statutory Income Tax Rate to Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Federal statutory tax rate	21.00%	21.00%
State tax, net of federal benefit	6.98%
Nondeductible expenses	(0.09%)	0.14%
Tax credits	6.15%	2.02%
Change in valuation allowance	(41.38%)	(23.15%)
Prior year true-up for state net operating losses	6.96%
Other	0.38%	(0.01%)
Effective tax rate	0.00%	0.00%

Income Taxes - Schedule of Significant Components of Net Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 16,381	$ 6,259
Accruals	326	151
Intangible assets	143	119
Tax credits	2,500	682
Other	109	25
Total gross deferred tax assets	19,459	7,236
Valuation allowance for deferred tax assets	$ (19,459)	$ (7,236)

Income Taxes - Schedule of Reconciliation of Beginning and Ending Balance of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Balance at the beginning of the year	$ 398	$ 230
Increase of unrecognized tax benefits taken in prior years	10
Increase of unrecognized tax benefits related to current year	686	168
Balance at the end of the year	$ 1,094	$ 398

401(k) Retirement Savings Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
401(K) Plan
Defined Benefit Plan Disclosure [Line Items]
Matching employer contributions	$ 0	$ 0

Net Loss Per Share - Schedule of Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss	$ (29,539)	$ (13,088)
Denominator:
Weighted-average common shares outstanding	5,991,213	764,408
Net loss per share, basic and diluted	$ (4.93)	$ (17.12)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Net Loss Per Share - Schedule of Potentially Dilutive Securities not Included in Calculation of Diluted Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per share	2,302,889	5,189,621
Series A Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per share		4,280,690
Shares Subject to Outstanding Common Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per share	2,278,771	859,322
Estimated Shares Issuable Under Employee Stock Purchase Plan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per share	24,118
Shares Subject to Common Stock Warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potential dilutive securities excluded from diluted net loss per share		49,609

Subsequent Events - Additional Information (Details)	1 Months Ended				12 Months Ended
Subsequent Events - Additional Information (Details)	Mar. 31, 2021 USD ($) Installment	Jan. 31, 2021 shares	Apr. 30, 2020 Installment	Sep. 30, 2019 USD ($)	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 shares
Subsequent Event [Line Items]
Aggregate principal amount					$ 4,476,000
Term Loan \| Silicon Valley Bank
Subsequent Event [Line Items]
Aggregate principal amount				$ 4,500,000
Frequency of payments					monthly
Number of Monthly Installments \| Installment			21
End of term payment, percentage			6.00%
Term Loan \| Silicon Valley Bank \| Maximum
Subsequent Event [Line Items]
Debt instrument prepayment fee percentage				3.00%
Term Loan \| Silicon Valley Bank \| Minimum
Subsequent Event [Line Items]
Debt instrument prepayment fee percentage				1.00%
Second Tranche Term Loan \| Silicon Valley Bank
Subsequent Event [Line Items]
Aggregate principal amount				$ 2,000,000
Performance Stock Options
Subsequent Event [Line Items]
Options granted to purchase shares of common stock \| shares					127,042
Performance Stock Options \| Certain Executive Officers
Subsequent Event [Line Items]
Options granted to purchase shares of common stock \| shares					127,042
2020 Equity Incentive Plan
Subsequent Event [Line Items]
Options granted to purchase shares of common stock \| shares					1,775,808	485,150
Subsequent Event \| Term Loan \| Silicon Valley Bank
Subsequent Event [Line Items]
Aggregate principal amount	$ 30,000,000
Debt instrument, maturity date	Jan. 01, 2026
Frequency of payments	monthly
Number of Monthly Installments \| Installment	37
End of term payment, percentage	9.50%
Subsequent Event \| Term Loan \| Silicon Valley Bank \| Maximum
Subsequent Event [Line Items]
Debt instrument prepayment fee percentage	3.00%
Subsequent Event \| Term Loan \| Silicon Valley Bank \| Minimum
Subsequent Event [Line Items]
Debt instrument prepayment fee percentage	1.00%
Subsequent Event \| First Tranche Term Loan \| Silicon Valley Bank
Subsequent Event [Line Items]
Aggregate principal amount	$ 20,000,000
Repayment of outstanding obligations	$ 5,000,000
Debt instrument, maturity date	Dec. 31, 2021
End of term payment, percentage	6.00%
Subsequent Event \| Second Tranche Term Loan \| Silicon Valley Bank
Subsequent Event [Line Items]
Aggregate principal amount	$ 10,000,000
Debt instrument, maturity date	Dec. 31, 2022
Floating interest rate scenario one	4.25%
Debt instrument basis spread variable rate scenario two	6.25%
Number of Monthly Installments \| Installment	25
Subsequent Event \| Second Tranche Term Loan \| Silicon Valley Bank \| Prime Rate \| Maximum
Subsequent Event [Line Items]
Debt instrument basis spread variable rate scenario one	1.00%
Debt instrument basis spread variable rate scenario two	3.00%
Subsequent Event \| Performance Stock Options
Subsequent Event [Line Items]
Options granted to purchase shares of common stock \| shares		19,003
Subsequent Event \| 2020 Equity Incentive Plan
Subsequent Event [Line Items]
Options granted to purchase shares of common stock \| shares		351,000