Satsuma Pharmaceuticals (STSA) 10-K 15 Mar 22 2021 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Mar. 11, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Registrant Name	Satsuma Pharmaceuticals, Inc.
Entity Central Index Key	0001692830
Entity Current Reporting Status	Yes
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Public Float			$ 159
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
ICFR Auditor Attestation Flag	false
Entity File Number	001-39041
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-3039831
Entity Address, Address Line One	400 Oyster Point Boulevard
Entity Address, Address Line Two	Suite 221
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	410-3200
Document Annual Report	true
Document Transition Report	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	STSA
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		31,545,564
Auditor Name	KPMG LLP
Auditor Location	San Diego, California
Auditor Firm ID	185
Documents Incorporated by Reference	Portions of the registrant’s definitive Proxy Statement relating to the 2022 Annual Meeting of Stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10-K to the extent stated herein. The proxy statement will be filed with the Securities and Exchange Commission within 120 days of the registrant’s fiscal year ended December 31, 2021.

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets
Cash and cash equivalents	$ 15,835	$ 36,326
Short-term marketable securities	77,315	31,910
Prepaid expenses and other current assets	6,698	5,550
Total current assets	99,848	73,786
Property and equipment, net	6,792	6,473
Long-term marketable securities	2,620
Other non-current assets	572	774
Total assets	109,832	81,033
Liabilities
Accounts payable	1,469	3,381
Accrued and other current liabilities	5,943	2,675
Current portion of long-term debt	1,080	1,990
Total current liabilities	8,492	8,046
Long-term debt		1,042
Other noncurrent liabilities		9
Total liabilities	8,492	9,097
Commitments and Contingencies (Note 5)
Stockholders’ equity
Preferred stock, $0.0001 par value, 10,000,000 shares authorized as of December 31, 2021 and December 31, 2020; no shares issued and outstanding as of December 31, 2021 and December 31, 2020
Common stock, $0.0001 par value, 300,000,000 shares authorized as of December 31, 2021 and December 31, 2020, respectively; 31,545,564 shares and 17,436,978 shares issued and outstanding as of December 31, 2021 and December 31, 2020, respectively	3	2
Additional paid-in-capital	243,115	162,469
Accumulated other comprehensive (loss) income	(42)	29
Accumulated deficit	(141,736)	(90,564)
Total stockholders’ equity	101,340	71,936
Total liabilities, preferred stock and stockholders' equity	$ 109,832	$ 81,033

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	31,545,564	17,436,978
Common stock, shares outstanding	31,545,564	17,436,978

Statements of Operations and Co

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating expenses
Research and development	$ 37,635	$ 36,270
General and administrative	13,531	12,058
Total operating expenses	51,166	48,328
Loss from operations	(51,166)	(48,328)
Interest income	157	1,115
Interest expense	(163)	(350)
Net loss	(51,172)	(47,563)
Unrealized (loss) gain on marketable securities	(71)	12
Comprehensive loss	$ (51,243)	$ (47,551)
Net loss per share attributable to common stockholders, basic and diluted	$ (1.75)	$ (2.73)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	29,174,386	17,405,688

Statements of Stockholders' Equ

Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning balance at Dec. 31, 2019	$ 115,335	$ 2	$ 158,317	$ (43,001)	$ 17
Beginning balance, Shares at Dec. 31, 2019		17,382,047
Issuance of common stock upon exercise of stock options	82		82
Issuance of common stock upon exercise of stock options, Shares		35,265
Stock-based compensation	4,018		4,018
Issuance of common stock upon purchases under employee share purchase plan	52		52
Issuance of common stock upon purchases under employee share purchase plan, Shares		14,766
Issuance of common stock upon net exercise of common stock warrants, Shares		4,900
Other comprehensive income	12				12
Net loss	(47,563)			(47,563)
Ending balance at Dec. 31, 2020	71,936	$ 2	162,469	(90,564)	29
Ending Balance, Shares at Dec. 31, 2020		17,436,978
Issuance of common stock upon exercise of stock options	8		8
Issuance of common stock upon exercise of stock options, Shares		7,932
Issuance of common stock upon initial public offering,net of issuance cost	75,215	$ 1	75,214
Issuance of common stock in private placement financing, net of issuance costs, Shares		14,084,507
Stock-based compensation	5,364		5,364
Issuance of common stock upon purchases under employee share purchase plan	60		60
Issuance of common stock upon purchases under employee share purchase plan, Shares		16,147
Other comprehensive income	(71)				(71)
Net loss	(51,172)			(51,172)
Ending balance at Dec. 31, 2021	$ 101,340	$ 3	$ 243,115	$ (141,736)	$ (42)
Ending Balance, Shares at Dec. 31, 2021		31,545,564

Statements of Stockholders' E_2

Statements of Stockholders' Equity (Parenthetical) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
Statement Of Stockholders Equity [Abstract]
Common stock issuance costs	$ 4,785

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities
Net loss	$ (51,172)	$ (47,563)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation	393	239
Loss on disposal of property and equipment	618
Non-cash interest expense, and amortization of debt discount and issuance costs	48	102
Amortization of premiums / (accretion of discounts), net on marketable securities	651	83
Stock-based compensation	5,364	4,018
Changes in assets and liabilities
Prepaid expenses and other assets	(946)	1,455
Accounts payable	(1,212)	(1,625)
Accrued and other current liabilities	3,268	974
Other non-current liabilities	(9)	(10)
Net cash used in operating activities	(42,997)	(42,327)
Cash flows from investing activities
Purchases of marketable securities	(88,620)	(34,008)
Proceeds from maturities of marketable securities	39,873	97,172
Purchases of property and equipment	(2,030)	(5,165)
Net cash (used in) provided by investing activities	(50,777)	57,999
Cash flows from financing activities
Repayment of debt	(2,000)	(2,000)
Proceeds from private placement financing, net of issuance costs	75,215
Payment of offering costs		(235)
Proceeds from issuance of common stock under employee plans	68	134
Net cash provided by (used in) financing activities	73,283	(2,101)
Net (decrease) increase in cash and cash equivalents	(20,491)	13,571
Cash and cash equivalents
Cash and cash equivalents, at beginning of period	36,326	22,755
Cash and cash equivalents, at end of period	15,835	36,326
Supplemental disclosure of cash flow information:
Cash paid for income taxes	5
Cash paid for interest	126	259
Supplemental non-cash investing and financing activities:
Purchases of property and equipment in accounts payable and accrued and other current liabilities	$ 24	$ 724

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Organization and Summary of significant Accounting Policies	1. Organization and Summary of Significant Accounting Policies Description of the Business Satsuma Pharmaceuticals, Inc. (the “Company”) is a clinical-stage biopharmaceutical company developing a novel therapeutic for the acute treatment of migraine. The Company’s product candidate, STS101, is a drug-device combination of a proprietary dry-powder formulation of dihydroergotamine mesylate, or DHE, which can be quickly and easily self-administered by a proprietary pre-filled, single-use, nasal delivery device. The Company, headquartered in South San Francisco, was incorporated in 2016 in the state of Delaware. Private Placement In February 2021, the Company entered into a Securities Purchase Agreement with certain purchasers, pursuant to which the Company agreed to sell and issue to certain purchasers an aggregate of 14,084,507 shares of its common stock at a per share purchase price of $5.68, the closing price of its common stock on the Nasdaq Global Market on February 26, 2021, for gross proceeds of $80.0 million (“Private Placement”). The Private Placement closed in March 2021 and the Company received $75.2 million in net proceeds after deducting commissions and offering expenses. Liquidity The Company is subject to risks and uncertainties common to early-stage companies in the biopharmaceutical industry, including, but not limited to, risks of clinical delays or failure, development by competitors of new technological innovations, protection of proprietary technology, dependence on key personnel, reliance on contract manufacturing organizations (“CMOs”), contract research organizations (“CROs”), compliance with government regulations and the need to obtain additional financing to fund operations. STS101 is an investigational product candidate that will require additional clinical development prior to any submission for regulatory approval and commercialization, if approved. These efforts require significant amounts of additional capital, adequate personnel, infrastructure, and extensive compliance and reporting. The Company has incurred significant losses and negative cash flows from operations in all periods since its inception and had an accumulated deficit of $141.7 million as of December 31, 2021. The Company has historically financed its operations primarily through its initial public offering (“IPO”), and private placements of its equity securities and borrowings under its long-term debt facility. The Company has no products approved for sale, and the Company has not generated any revenue since its inception. The Company expects to incur significant additional operating losses over at least the next several years. There can be no assurance that in the event the Company requires additional financing, such financing will be available on terms which are favorable or at all. Failure to generate sufficient cash flows from operations or raise additional capital to support its operations would have a material adverse effect on the Company’s ability to achieve its intended business objectives. As of December 31, 2021, the Company had cash, cash equivalents and marketable securities of $95.8 million. The Company’s management believes that the Company’s current cash, cash equivalents and marketable securities will be sufficient to fund its planned operations for at least 12 months from the date of the issuance of these annual financial statements. Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”), as defined by the Financial Accounting Standards Board, or the FASB. 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 and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Such estimates include the accrual of research and development expenses, useful lives of property and equipment and the fair value of stock-based awards. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the impact of the COVID-19 pandemic which may delay the enrollment of subjects for our clinical trials and may disrupt our supply chain for development and manufacturing activities, and adjust those estimates and assumptions when facts and circumstances dictate. Actual results could differ materially from those estimates and assumptions. Segments The Company operates and manages its business as a single As of December 31, 2021, the Company’s long-lived assets of $0.1 million were located in the United States and $6.7 million in the United Kingdom and Europe. As of December 31, 2020, of $1.5 million Cash and Cash Equivalents The Company considers all highly liquid investments purchased with an original or remaining maturity of three months or less at the date of purchase to be cash equivalents. Marketable Debt Securities The Company determines the appropriate classification of its marketable debt securities at the time of purchase and reevaluates such designation at each balance sheet date. All marketable debt securities are considered available-for-sale and carried at estimated fair values and reported in cash equivalents, short-term marketable securities or long-term marketable securities. Unrealized gains and losses on available-for-sale debt securities are excluded from net income and reported in accumulated other comprehensive income (loss) as a separate component of stockholders’ equity. Interest income includes amortization of purchase premiums and discounts, realized gains and losses on sales of securities and other-than-temporary declines in the fair value of securities, if any. The cost of securities sold is based on the specific identification method. The Company regularly reviews all its investments for other-than-temporary declines in fair value . The review includes the consideration of the cause of the impairment, including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses, whether the Company has the intent to sell the securities and whether it is more likely than not that the Company will be required to sell the securities before the recovery of their amortized cost basis. When determines that the decline in fair value of an investment is below its accounting basis and the decline is other-than-temporary, the Company reduces the carrying value of the security it holds and records a loss for the amount of such decline. Concentration of Credit Risk The Company has no significant off-balance sheet concentrations of credit risk. Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents and marketable securities. Substantially all the Company’s cash is held by one financial institution that management believes to be of high credit quality. Such deposits may, at times, exceed federally insured limits. The Company invests its cash equivalents in marketable securities and money market funds. The Company has not experienced any credit losses on its deposits of cash or cash equivalents. Fair Value of Financial Instruments The carrying amounts of certain of the Company’s financial instruments, including cash equivalents, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities and market interest rates, if applicable. Refer to Note 2 for details on the fair value of marketable securities. Deferred Offering Costs The Company capitalizes costs that are directly associated with in-process equity financings until such financings are consummated at which time such costs are recorded against the gross proceeds of the offering. Should the in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the statements of operations and comprehensive loss. Property and Equipment, Net Property and equipment are stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which generally ranges from three to five years. Leasehold improvements are stated at cost and amortized over the shorter of the useful lives of the assets or the lease term. Maintenance and repairs are charged to expense as incurred. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the balance sheet and any resulting gain or loss is reflected in the statements of operations and comprehensive loss in the period realized. Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. The Company reviews property and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset or asset group may not be recoverable or that the useful life is shorter than the Company had originally estimated. Recoverability is measured by comparison of the carrying amount of the asset or asset group to the future undiscounted cash flows which the asset or asset group is expected to generate. If the asset or asset group is considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset or asset group exceeds the fair value of the asset or asset group. If the useful life is shorter than originally estimated, the Company amortizes the remaining carrying value over the new shorter useful life. There have been no such impairments of long-lived assets during the years ended December 31, 2021 and 2020. Research and Development Expenses The Company’s research and development expenses consist primarily of payroll and personnel-related expenses, including salaries, employee benefit costs and stock-based compensation expenses for the Company’s research and product development employees, fees paid to third parties to conduct preclinical and clinical studies and other research and development activities on behalf of the Company, including CROs, CMOs and other service providers, costs for licenses, and allocated overhead, including rent, equipment, depreciation, information technology costs and utilities. The Company charges all research and development costs, both internal and external, to research and development expenses within the statements of operations and comprehensive loss as incurred. 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 also expensed as incurred. Accrued Research and Development The Company monitors the activity under its various agreements with CROs, CMOs and other service providers to the extent possible through communication with each service provider, detailed invoice and task completion review, analysis of actual expenses against budget, pre-approval of any changes in scope, and review of contractual terms. The Company’s research and development accruals are estimated based on the level of services performed, progress of the studies, including the phase or completion of events, and contracted costs. These estimates may or may not match the actual services performed by the service providers. The estimated costs of research and development provided, but not yet invoiced, are included accrued and other current liabilities on the balance sheet. 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 made to service providers under these arrangements in advance of the performance of the related services are recorded as prepaid expenses and other current assets on the balance sheet until the services are rendered. Stock-Based Compensation The Company maintains incentive plans under which incentive stock options and nonqualified stock options may be granted to employees and non-employee service providers. The Company accounts for all shared-based awards granted to employees and non-employees based on the fair value on the date of grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the respective award. The Company accounts for forfeitures as they occur. Generally, the Company Estimating fair value of stock-based awards using an option pricing model requires input of subjective assumptions, including fair value of the Company’s common stock, and, for stock options, expected term of options and stock price volatility. The Company uses the Black-Scholes option-pricing model to value its stock option awards. The assumptions used in calculating the fair value of stock-based awards represent management’s estimates, involve inherent uncertainties and require application of management’s judgment. As a result, if factors change and management uses different assumptions, stock-based compensation expense could be materially different for future The Company classifies stock-based compensation expense in its statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified. Comprehensive Income (Loss) Comprehensive gain or loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. In 2021 the Company recorded unrealized loss on marketable securities of $0.1 million and in 2020 the company recorded an unrealized gain of less than $0.1 million in other comprehensive income (loss). Net Loss per Share Attributable to Common Stockholders Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share 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, outstanding stock options are considered to be potentially dilutive securities. Because the Company has reported a net loss for all periods presented, diluted Income Taxes Income taxes are recorded using an asset and liability approach. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Deferred tax assets are reduced by a valuation allowance if current evidence indicates that it is considered more likely than not that these benefits will not be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company’s tax positions are subject to income tax audits. The Company recognizes the tax benefit of an uncertain tax position only if it is more likely than not that the position is sustainable upon examination by the taxing authority, based on the technical merits. The tax benefit recognized is measured as the largest amount of benefit which is more likely than not to be realized upon settlement with the taxing authority. The Company recognizes interest accrued and penalties related to unrecognized tax benefits in its tax provision. The Company evaluates uncertain tax positions on a regular basis. The evaluations are based on a number of factors, including changes in facts and circumstances, changes in tax law, correspondence with tax authorities during the course of the audit, and effective settlement of audit issues. The provision for income taxes includes the effects of any accruals that the Company believes are appropriate, as well as the related net interest and On June 29, 2020 California State Assembly Bill 85 (the “Trailer Bill”) was enacted which suspends the use of California net operating loss (“NOL”) deductions and certain tax credits, including research and development tax credits, for the 2020, 2021, and 2022 tax years. Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740) Simplifying the Accounting for Income Taxes. ASU 2019-12 New Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) Leases In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326)

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	2. Fair Value Measurements The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a three-tier fair value hierarchy has been established, which prioritizes the inputs used in measuring fair value as follows: Level 1—Observable inputs, such as quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2—Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs which reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. In determining fair value, the Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible as well as considers counterparty credit risk in its assessment of fair value. As of December 31, 2021, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at December 31, 2021 Quoted Price in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets U.S. government bonds $ 4,667 $ — $ — $ 4,667 Foreign government agency bonds (1) — 6,526 — 6,526 Corporate bonds — 49,989 — 49,989 Asset backed securities — 18,753 — 18,753 Marketable securities 4,667 75,268 — 79,935 Money market funds (2) 15,809 — — 15,809 Total fair value of assets $ 20,476 $ 75,268 $ — $ 95,744 (1) Consists of short-term agency bonds of Asian Development Bank and International Bank for Reconstruction and Development. (2) Included in cash and cash equivalents on the balance sheet. Fair Value Measurements at December 31, 2021 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimate Fair Value Assets U.S. government bonds 4,670 — $ (3 ) 4,667 Foreign government agency bonds (1) 6,530 — (4 ) 6,526 Corporate bonds 50,008 — (19 ) 49,989 Asset backed securities 18,769 — (16 ) 18,753 Marketable securities 79,977 — (42 ) 79,935 Money market funds (2) 15,809 — — 15,809 Total fair value of assets $ 95,786 $ — $ (42 ) $ 95,744 (1) Consists of short-term agency bonds of Asian Development Bank and International Bank for Reconstruction and Development. (2) Included in cash and cash equivalents on the balance sheet. As of December 31, 2020, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at December 31, 2020 Quoted Price in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Corporate bonds $ — $ 31,910 $ — $ 31,910 Marketable securities — 31,910 — 31,910 Money market funds (1) 36,304 — — 36,304 Total fair value of assets $ 36,304 $ 31,910 $ — $ 68,214 (1) Included in cash and cash equivalents on the balance sheet. Fair Value Measurements at December 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimate Fair Value Assets Corporate bonds $ 31,881 $ 30 $ (1 ) $ 31,910 Marketable securities 31,881 30 (1 ) 31,910 Money market funds (1) 36,304 — — 36,304 Total fair value of assets $ 68,185 $ 30 $ (1 ) $ 68,214 (1) Included in cash and cash equivalents on the balance sheet. There were no transfers of assets or liabilities between the fair value measurement levels during the years ended December 31, 2021 and 2020. There were no financial liabilities measured and recognized at fair value as of December 31, 2021 and December 31, 2020. As of December 31, 2021, the fair value of the Term Loan (as defined in Note 4 below) approximated the carrying amount of the loan as the Term Loan bears floating interest rate that approximates the market rate.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	3. Balance Property and Equipment, Net Property and equipment consisted of the following (in thousands, except years): December 31, Useful Life (In Years) 2021 2020 Furniture and fixtures 3-5 $ 75 $ 63 Leasehold improvements Shorter of useful life or lease term 62 62 Machinery and equipment 6 1,084 933 Tooling 6 974 840 Construction in progress — 5,219 5,008 7,414 6,906 Less: Accumulated depreciation (622 ) (433 ) $ 6,792 $ 6,473 Depreciation is computed using the straight-line method. Depreciation expense was $0.4 million and $0.2 million Accrued and Other Current Liabilities Accrued and other current liabilities consisted of the following (in thousands): December 31, 2021 2020 Accrued salaries and benefits $ 2,117 $ 1,330 Accrued research and development expenses 3,396 910 Accrued professional services 361 232 Accrued interest 5 16 Other 64 187 $ 5,943 $ 2,675

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Long-Term Debt	4 . Long-Term Debt On October 26, 2018, the Company entered into a Loan and Security Agreement (the “Loan Agreement”) with Silicon Valley Bank. The Loan Agreement provided for loan advances of up to $10.0 million. The first advance (the “Term A Loan”) of $5.0 million was available for draw down by the Company as of the effective date of the Loan Agreement. The remaining $5.0 million under the facility was never drawn down and is no longer available for draw. Interest on the loan advances is payable monthly at a floating per annum rate equal to the greater of 1.5% above the prime rate or 6.5%. Upon the occurrence of an event of default, interest will increase to 5.0% above the rate that is otherwise applicable. The maturity date of the loan advances is May 1, 2022. The effective interest rate of the Term Loan approximates its stated interest rates. Principal on the Term A Loan is repayable commencing on December 1, 2019 in 30 monthly payments through maturity. In addition to regular monthly payments, a final payment equal to the original principal amount of the Term Loans multiplied by 5.0% is due on the earliest to occur of (a) May 1, 2022 or (b) the prepayment in full of the term loan advances. As of December 31, 2021, the Term A Loan advances, net of debt discount and debt issuance costs, were $1.1 million and are included in current portion of long-term debt on the Company’s balance sheets. As of December 31, 2021, the future contractual maturities of debt by fiscal year are as follows (in thousands): 2022 $ 833 Total future maturities of debt $ 833 In accordance with the terms of the Loan Agreement, on October 26, 2018, the Company issued warrants to purchase 10,232 shares of the Company’s common stock at an exercise price of $1.04 per share with a term of 10 years. The fair value of the warrants of less than $0.1 million (estimated using the Option Pricing Model, or OPM) was accounted as a debt discount and accreted over the term of the Term A Loan using the effective interest rate method. The warrants were accounted for and classified as equity at the fair value and were not subject to subsequent remeasurement to fair value. There were no common stock warrants outstanding as of December 31, 2021 and 2020. The proceeds from the Term A Loan advance were allocated to the debt and the warrants based on their relative fair values. The resulting debt discount of less than $0.1 million is being recognized as interest expense over the term of the loan of 3.6 years using the effective interest method. The Company incurred debt issuance costs of $0.1 million, which is presented as reduction of the Term A Loan advance, consistent with the presentation of debt discount. Debt issuance cost and final payment of $0.3 million is recognized as additional interest expense using the effective interest method over the term of the loan. The Company accreted the final payment due at maturity using the effective interest rate method. The accrued liabilities related to the accretion of the final payment were $0.2 million and $0.2 million as of December 31, 2021 and December 31, 20 20 , respectively, which was included in long-term debt and in the current portion of long-term debt on the Company’s balance sheets , respectively .

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	5 . Commitments and Operating Leases On January 9, 2018, the Company entered into an office lease agreement for office space in South San Francisco, California. The lease term was through April 30, 2021 and was amended in March 2021 to extend it through October 31, 2021. In October 2021, the Company entered into second amendment of the office lease agreement which extended the lease term through October 31, 2022. In July 2019, the Company entered into a lease agreement to lease another office space in North Carolina. Тhe lease term for this office space was three years and was schedule to expire in July 2022 Rent expense was $0.3 million and $0.3 million for the years ended December 31, 2021 and 2020, respectively. As of December 31, 2021, less than $0.1 million of deferred rent representing future minimum rental payments for leases with scheduled rent escalations was included in accrued and other current liabilities on the Company’s balance sheet. Future minimum lease payments under non-cancelable operating leases as of December 31, 2021 were as follows (in thousands): Operating Leases 2022 $ 201 Total minimum lease payments $ 201 Contingencies From time to time, the Company may be involved in litigation related to claims that arise in the ordinary course of its business activities. The Company accrues for these matters when it is probable that future expenditures will be made, and these expenditures can be reasonably estimated. As of December 31, 2021 and 2020, the Company did not believe that any such matters, individually or in the aggregate, would have a material adverse effect on the Company’s financial position, results of operations or cash flows. Indemnification The Company enters into standard indemnification arrangements in the ordinary course of business. Pursuant to these arrangements, the Company indemnifies, holds harmless and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party, in connection with any trade secret, copyright, patent or other intellectual property infringement claim by any third party with respect to its technology. The term of these indemnification agreements is generally perpetual any time after the execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these arrangements is not determinable. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements. As a result, the Company believes the fair value of these agreements is

Preferred Stock

Preferred Stock	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Preferred Stock	6. Preferred Stock As of December 31, 2021 and 2020, the Company’s certificate of incorporation, as amended and restated, authorized the Company to issue up to 10,000,000 shares of preferred stock at the par value of $0.0001 per share. As of December 31, 2021 and 2020, there were no shares of preferred stock issued and outstanding.

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Common Stock	7 . Common The Company has authorized 300,000,000 shares of common stock, $0.0001 par value per share. Each holder of shares of common stock shall be entitled to one vote for each share thereof held. The Company had reserved common stock, on an as-converted basis, for future issuance as follows: December 31, 2021 2020 Exercise of outstanding options 3,202,588 3,162,459 Shares of common stock available for grant under the 2019 Plan 1,493,893 844,475 Shares of common stock available for ESPP 477,276 319,054 Total 5,173,757 4,325,988

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	8 . Stock-Based 2019 Incentive Award Plan The Company’s board of directors adopted and the Company’s stockholders approved, effective on the day of effectiveness of the registration statement on Form S-1, the 2019 Incentive Award Plan (the “2019 Plan”). Awards granted under the 2019 Plan may be either incentive stock options (“ISOs”), nonqualified stock options (“NSOs”), stock appreciation rights (“SARs”), or restricted stock units (“RSUs”). ISOs may be granted only to Company employees (including officers and directors who are also employees). 2016 Incentive Award Plan In 2016, the Company established its 2016 Equity Incentive Plan (the “2016 Plan”) which provides for the granting of stock options to employees and consultants of the Company. Awards granted under the 2016 Plan may be either incentive stock options (“ISOs”), nonqualified stock options (“NSOs”), stock appreciation rights (“SARs”), or restricted stock units (“RSUs”). ISOs may be granted only to Company employees (including officers and directors who are also employees). NSOs may be granted to Company employees and consultants. The exercise price of ISOs and NSOs shall not be less than 100% of the estimated fair value of the shares on the date of grant. The exercise price of ISOs granted to an employee who, at the time of grant, owns stock representing more than 10% (“10% stockholder”) of the voting power of all classes of stock of the Company shall be no less than 110% of the estimated fair value of the shares on the date of grant. The options usually have a term of 10 years (or no more than five years if granted to a 10% stockholder). Vesting conditions determined by the plan administrator may apply to stock options and four-year In January 2022, the number of shares of common stock available for issuance under the 2019 Plan was increased by 1,261,822 shares as a result of the automatic increase provision in the 2019 Plan. Activity under the 2019 Plan and 2016 Plan is set forth below: Outstanding Options Shares Available for Grant Number of Shares Weighted Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Balance, January 1, 2020 1,778,044 1,568,874 $ 3.55 8.85 Additional shares authorized 695,281 Options granted (1,669,200 ) 1,669,200 $ 14.56 9.63 Options exercised — (35,265 ) $ 2.34 Options cancelled 40,350 (40,350 ) $ 8.83 Balance, December 31, 2020 844,475 3,162,459 $ 9.31 8.79 Additional shares authorized 697,479 Options granted (129,000 ) 129,000 $ 4.85 9.65 Options exercised — (7,932 ) $ 1.04 Options cancelled 80,939 (80,939 ) $ 9.77 Balance, December 31, 2021 1,493,893 3,202,588 $ 9.14 7.73 Exercisable as of December 31, 2021 1,678,549 $ 8.27 7.04 Vested and expected to vest, December 31, 2021 3,202,588 $ 9.14 7.73 The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying stock options and the fair value of the Company’s common stock for stock options that were in-the-money as of December 31, 2021 and December 31, 2020. The aggregate intrinsic value of options vested and expected to vest as of December 31, 2021 and December 31, 2020 was $2.2 million and $1.9 million, respectively. The aggregate intrinsic value of stock options exercised during the years ended on December 31, 2021 and 2020 was less than $0.1 million and $0.8 million, respectively. The weighted-average grant-date fair value of options granted during the years ended December 31, 2021 and December 2020 was $3.66 and $9.62 per share, respectively. As of December 31, 2021, the total unrecognized stock-based compensation expense for stock options was $9.6 million, which is expected to be recognized over a weighted-average period of 2.2 years. The The Company accounts for forfeitures as they occur. Stock-Based Compensation Associated with Awards to Employees and Non-employees The Company estimated the fair value of stock options using the Black Scholes option-pricing model. The fair value of stock options was valued using the following assumptions: December 31, 2021 2020 Expected term (years) 5.8 - 6.1 5.5 - 6.1 Expected volatility 91.5%-98.6% 71.2% - 92.5% Risk-free interest rate 0.6%-1.4% 0.3% - 1.7% Dividend yield 0% 0% Expected Term . The expected term is calculated using the simplified method, which is available where there is insufficient historical data about exercise patterns and post-vesting employment termination behavior. The simplified method is based on the vesting period and the contractual term for each grant, or for each vesting-tranche for awards with graded vesting. The mid-point between the vesting date and the maximum contractual expiration date is used as the expected term under this method. For awards with multiple vesting-tranches, the periods from grant until the mid-point for each of the tranches are averaged to provide an overall expected term. Expected Volatility . The Company used an average historical stock price volatility of a peer group of publicly traded companies to be representative of its expected future stock price volatility, as the Company has limited trading history for its common stock. For purposes of identifying these peer companies, the Company considered the industry, stage of development, size and financial leverage of potential comparable companies. For each grant, the Company measured historical volatility over a period equivalent to the expected term. Risk-Free Interest Rate . The risk-free interest rate is based on the implied yield currently available on U.S. Treasury zero-coupon issues with a remaining term equivalent to the expected term of a stock award. Expected Dividend . The Company has not paid any dividends and does not anticipate paying any dividends in the near future. Accordingly, the Company has estimated the dividend yield to be zero Fair Value of Common Stock Prior to the IPO the fair value of the Company’s common stock underlying the stock options was determined by the Board of Directors with assistance from management and, in part, on input from an independent third-party valuation firm. The Board of Directors determined the fair value of common stock by considering a number of objective and subjective factors, including valuations of comparable companies, sales of convertible preferred stock, operating and financial performance, the lack of liquidity of the Company’s common stock and the general and industry-specific economic outlook. Subsequent to the Company’s IPO, the fair value of the Company’s common stock is determined based on its closing market price. 2019 Employee Share Purchase Plan In September 2019, the Company adopted the 2019 Employee Share Purchase Plan (“ESPP”), which became effective on the business day prior to the effectiveness of the registration statement relating to the IPO. A total of 160,000 shares of common stock were initially reserved for issuance under the ESPP. The ESPP permits eligible employees to acquire shares of the Company’s common stock through periodic payroll deductions of up to 15% of base compensation. No employee may purchase more than 50,000 shares during an offering period. In addition, no employee may purchase more than $25,000 worth of stock, determined by the fair market value of the shares at the time such option is granted, in one calendar year. 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 on the first trading day of the offering period or on the last trading day of the offering period. The first offering period was for 6.5 months beginning from May 1, 2020 until November 15, 2020. The Company issued 14,766 shares under the ESPP for the year ended December 31, 2020. The second offering period was for 5.5 months beginning from July 1, 2021 until December 15, 2021. The Company issued 16,147 shares under the ESPP for the year ended December 31, 2021. Shares authorized for future purchase under the ESPP were 477,276 at December 31, 2021. In January 2022, the number of shares of common stock available for issuance under the ESPP was increased by 315,455 shares as a result of the automatic increase provision in the ESPP. The offering period and purchase period is determined by the board of directors. The Company entered into an additional offering period beginning December 16, 2021 and ending June 15, 2022. Compensation expense is calculated using the fair value of the employees' purchase rights under the Black-Scholes option pricing model. December 31, 2021 2020 Expected term (years) 0.5 0.5 Expected volatility 58.8% 111.0% Risk-free interest rate 0.50% 0.1% Dividend yield 0% 0% As of December 31, 2021, the Company had unrecognized employee stock-based compensation relating to ESPP awards of less than $0.1 million, which is expected to be recognized over a weighted-average period of 0.5 years. Stock-Based Compensation Expense Total Year Ended December 31, 2021 2020 Research and development $ 1,777 $ 1,290 General and administrative 3,587 2,728 Total $ 5,364 $ 4,018 The above stock-based compensation expense related to the following equity-based awards: Year Ended December 31, 2021 2020 Stock options $ 5,338 $ 3,989 ESPP 26 29 Total $ 5,364 $ 4,018

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	9. The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data): Year Ended December 31, 2021 2020 Numerator: Net loss attributable to common stockholders $ (51,172 ) $ (47,563 ) Denominator: Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 29,174,386 17,405,688 Net loss per share attributable to common stockholders, basic and diluted $ (1.75 ) $ (2.73 ) The following outstanding shares of potentially dilutive securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the period presented because including them would have been antidilutive: Year Ended December 31, 2021 2020 Options to purchase common stock 3,202,588 3,162,459 Shares committed under ESPP 33,203 — Total 3,235,791 3,162,459

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	1 0 . Income Taxes No provision for income taxes was recorded for the years ended December 31, 2021 and 2020. The Company has incurred net operating losses only in the United States since its inception. The Company has not reflected any benefit of such net operating loss carryforwards in the financial statements. The differences between the statutory tax expense (benefit) rate and the effective tax expense (benefit) rate, were as follows (in thousands): Year Ended December 31, 2021 2020 Tax at federal statutory income tax rate $ (10,746 ) $ (9,988 ) Change in valuation allowance 12,877 9,950 Permanent differences 141 (20 ) Prior year true ups — 341 Research and development credits (2,374 ) (154 ) State income taxes (346 ) (128 ) Other 448 — Tax at effective income tax rate $ — $ 1 Significant components of the Company’s net deferred tax assets are summarized as follows (in thousands): December 31, 2021 2020 Deferred tax assets: Net operating loss carryforwards $ 27,511 $ 17,915 Research and development credit carryforwards 3,514 847 Stock-based compensation 1,189 697 Accruals and other 432 286 Gross deferred tax assets 32,646 19,745 Less: Valuation allowance (32,318 ) (19,441 ) Deferred tax assets, net of valuation allowance 328 304 Deferred tax liabilities: Property and equipment (328 ) (304 ) Net deferred tax assets $ — $ — As of December 31, 2021, the Company had federal and state net operating loss carryforwards (“NOLs”) of $130.4 million and $2.9 million, respectively. The Company also has California state research and development (“R&D”) credit carryforwards of $0.8 million, which do not expire and Federal R&D credit carryforwards of $3.3 million which will begin to expire in 2037. The Company has not performed a formal study validating these credits claimed in the tax returns. Once a study is prepared, the amount of R&D tax credits available could vary from what was originally claimed on the tax returns. As part of the Protecting Americans from Tax Hikes Act of 2015 (the “PATH Act”), certain eligible companies have the ability to convert a portion of their R&D tax credits to offset payroll tax liabilities. As of December 31, 2021, the Company had converted $1.2 million of its federal R&D credits to be utilized as an offset against future payroll taxes. The utilization of NOLs and tax credit carryforwards to offset future taxable income may be subject to an annual limitation as a result of ownership changes that have occurred previously or may occur in the future. Under Sections 382 and 383 of the Internal Revenue Code (“IRC”) a corporation that undergoes an ownership change may be subject to limitations on its ability to utilize its pre-change NOLs and other tax attributes otherwise available to offset future taxable income and/or tax liability. An ownership change is defined as a cumulative change of 50% or more in the ownership positions of certain stockholders during a rolling three-year period. The Company has not completed a formal study to determine if any ownership changes within the meaning of IRC Section 382 and 383 have occurred. If an ownership change has occurred, the Company’s ability to use its NOLs or tax credit carryforwards may be restricted, which could require the Company to pay federal or state income taxes earlier than would be required if such limitations were not in effect. Uncertain Income Tax Positions The The following table summarizes the activity related to the Company’s unrecognized tax benefits: Balance as of January 1, 2020 $ 238 Increase related to current year tax positions 80 Decrease related to prior year tax positions (162 ) Balance as of December 31, 2020 $ 156 Increase related to current year tax positions 213 Increase related to prior year tax positions 38 Balance as of December 31, 2021 $ 407 The Company’s policy is to account for interest and penalties as income tax expense. As of December 31, 2021, the Company had no interest related to unrecognized tax benefits. No amounts of penalties related to unrecognized tax benefits were recognized in the provision for income taxes. The Company does not anticipate any significant change within twelve months following the date of the filing of this Annual Report on Form 10-K The Company files income tax returns in the U.S. federal jurisdiction and various state jurisdictions. The Company is subject to U.S. federal and state income tax examination for calendar tax years beginning in 2016 due to net operating losses that are being carried forward for tax purposes.

Related Party Transaction

Related Party Transaction	12 Months Ended
	Dec. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	1 1 . Related Party The Company incurred expenses in connection with preclinical study services performed by SNBL of $0 and less than $0.1 million in the years ended December 31, 2021 and 2020, respectively, which are included in research and development expenses on the statements of operations and comprehensive loss. As of December 31, 2021 and 2020, the Company did not have any amounts due to SNBL. Two existing stockholders of the Company that are affiliated with directors of the Company purchased a total of 2,464,788 shares of the Company’s common stock, with an aggregate purchase price of $14.0 million, in the Private Placement.

Organization and Summary of S_2

Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Description of the Business	Description of the Business Satsuma Pharmaceuticals, Inc. (the “Company”) is a clinical-stage biopharmaceutical company developing a novel therapeutic for the acute treatment of migraine. The Company’s product candidate, STS101, is a drug-device combination of a proprietary dry-powder formulation of dihydroergotamine mesylate, or DHE, which can be quickly and easily self-administered by a proprietary pre-filled, single-use, nasal delivery device. The Company, headquartered in South San Francisco, was incorporated in 2016 in the state of Delaware.
Private Placement	Private Placement In February 2021, the Company entered into a Securities Purchase Agreement with certain purchasers, pursuant to which the Company agreed to sell and issue to certain purchasers an aggregate of 14,084,507 shares of its common stock at a per share purchase price of $5.68, the closing price of its common stock on the Nasdaq Global Market on February 26, 2021, for gross proceeds of $80.0 million (“Private Placement”). The Private Placement closed in March 2021 and the Company received $75.2 million in net proceeds after deducting commissions and offering expenses.
Liquidity	Liquidity The Company is subject to risks and uncertainties common to early-stage companies in the biopharmaceutical industry, including, but not limited to, risks of clinical delays or failure, development by competitors of new technological innovations, protection of proprietary technology, dependence on key personnel, reliance on contract manufacturing organizations (“CMOs”), contract research organizations (“CROs”), compliance with government regulations and the need to obtain additional financing to fund operations. STS101 is an investigational product candidate that will require additional clinical development prior to any submission for regulatory approval and commercialization, if approved. These efforts require significant amounts of additional capital, adequate personnel, infrastructure, and extensive compliance and reporting. The Company has incurred significant losses and negative cash flows from operations in all periods since its inception and had an accumulated deficit of $141.7 million as of December 31, 2021. The Company has historically financed its operations primarily through its initial public offering (“IPO”), and private placements of its equity securities and borrowings under its long-term debt facility. The Company has no products approved for sale, and the Company has not generated any revenue since its inception. The Company expects to incur significant additional operating losses over at least the next several years. There can be no assurance that in the event the Company requires additional financing, such financing will be available on terms which are favorable or at all. Failure to generate sufficient cash flows from operations or raise additional capital to support its operations would have a material adverse effect on the Company’s ability to achieve its intended business objectives. As of December 31, 2021, the Company had cash, cash equivalents and marketable securities of $95.8 million. The Company’s management believes that the Company’s current cash, cash equivalents and marketable securities will be sufficient to fund its planned operations for at least 12 months from the date of the issuance of these annual financial statements.
Basis of Presentation	Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“US GAAP”), as defined by the Financial Accounting Standards Board, or the FASB.
Use of Estimates	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 and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of income and expenses during the reporting period. Such estimates include the accrual of research and development expenses, useful lives of property and equipment and the fair value of stock-based awards. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors, including the impact of the COVID-19 pandemic which may delay the enrollment of subjects for our clinical trials and may disrupt our supply chain for development and manufacturing activities, and adjust those estimates and assumptions when facts and circumstances dictate. Actual results could differ materially from those estimates and assumptions.
Segments	Segments The Company operates and manages its business as a single As of December 31, 2021, the Company’s long-lived assets of $0.1 million were located in the United States and $6.7 million in the United Kingdom and Europe. As of December 31, 2020, of $1.5 million
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments purchased with an original or remaining maturity of three months or less at the date of purchase to be cash equivalents.
Marketable Debt Securities	Marketable Debt Securities The Company determines the appropriate classification of its marketable debt securities at the time of purchase and reevaluates such designation at each balance sheet date. All marketable debt securities are considered available-for-sale and carried at estimated fair values and reported in cash equivalents, short-term marketable securities or long-term marketable securities. Unrealized gains and losses on available-for-sale debt securities are excluded from net income and reported in accumulated other comprehensive income (loss) as a separate component of stockholders’ equity. Interest income includes amortization of purchase premiums and discounts, realized gains and losses on sales of securities and other-than-temporary declines in the fair value of securities, if any. The cost of securities sold is based on the specific identification method. The Company regularly reviews all its investments for other-than-temporary declines in fair value . The review includes the consideration of the cause of the impairment, including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses, whether the Company has the intent to sell the securities and whether it is more likely than not that the Company will be required to sell the securities before the recovery of their amortized cost basis. When determines that the decline in fair value of an investment is below its accounting basis and the decline is other-than-temporary, the Company reduces the carrying value of the security it holds and records a loss for the amount of such decline.
Concentration of Credit Risk	Concentration of Credit Risk The Company has no significant off-balance sheet concentrations of credit risk. Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash, cash equivalents and marketable securities. Substantially all the Company’s cash is held by one financial institution that management believes to be of high credit quality. Such deposits may, at times, exceed federally insured limits. The Company invests its cash equivalents in marketable securities and money market funds. The Company has not experienced any credit losses on its deposits of cash or cash equivalents.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of certain of the Company’s financial instruments, including cash equivalents, accounts payable and accrued liabilities approximate fair value due to their relatively short maturities and market interest rates, if applicable. Refer to Note 2 for details on the fair value of marketable securities.
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes costs that are directly associated with in-process equity financings until such financings are consummated at which time such costs are recorded against the gross proceeds of the offering. Should the in-process equity financing be abandoned, the deferred offering costs will be expensed immediately as a charge to operating expenses in the statements of operations and comprehensive loss.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at cost less accumulated depreciation. Depreciation is computed using the straight-line method over the estimated useful lives of the assets, which generally ranges from three to five years. Leasehold improvements are stated at cost and amortized over the shorter of the useful lives of the assets or the lease term. Maintenance and repairs are charged to expense as incurred. When assets are retired or otherwise disposed of, the cost and accumulated depreciation are removed from the balance sheet and any resulting gain or loss is reflected in the statements of operations and comprehensive loss in the period realized.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. The Company reviews property and equipment for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset or asset group may not be recoverable or that the useful life is shorter than the Company had originally estimated. Recoverability is measured by comparison of the carrying amount of the asset or asset group to the future undiscounted cash flows which the asset or asset group is expected to generate. If the asset or asset group is considered to be impaired, the impairment to be recognized is measured by the amount by which the carrying amount of the asset or asset group exceeds the fair value of the asset or asset group. If the useful life is shorter than originally estimated, the Company amortizes the remaining carrying value over the new shorter useful life. There have been no such impairments of long-lived assets during the years ended December 31, 2021 and 2020.
Research and Development Expenses	Research and Development Expenses The Company’s research and development expenses consist primarily of payroll and personnel-related expenses, including salaries, employee benefit costs and stock-based compensation expenses for the Company’s research and product development employees, fees paid to third parties to conduct preclinical and clinical studies and other research and development activities on behalf of the Company, including CROs, CMOs and other service providers, costs for licenses, and allocated overhead, including rent, equipment, depreciation, information technology costs and utilities. The Company charges all research and development costs, both internal and external, to research and development expenses within the statements of operations and comprehensive loss as incurred. 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 also expensed as incurred.
Accrued Research and Development	Accrued Research and Development The Company monitors the activity under its various agreements with CROs, CMOs and other service providers to the extent possible through communication with each service provider, detailed invoice and task completion review, analysis of actual expenses against budget, pre-approval of any changes in scope, and review of contractual terms. The Company’s research and development accruals are estimated based on the level of services performed, progress of the studies, including the phase or completion of events, and contracted costs. These estimates may or may not match the actual services performed by the service providers. The estimated costs of research and development provided, but not yet invoiced, are included accrued and other current liabilities on the balance sheet. 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 made to service providers under these arrangements in advance of the performance of the related services are recorded as prepaid expenses and other current assets on the balance sheet until the services are rendered.
Stock-Based Compensation	Stock-Based Compensation The Company maintains incentive plans under which incentive stock options and nonqualified stock options may be granted to employees and non-employee service providers. The Company accounts for all shared-based awards granted to employees and non-employees based on the fair value on the date of grant and recognizes compensation expense for those awards over the requisite service period, which is generally the vesting period of the respective award. The Company accounts for forfeitures as they occur. Generally, the Company Estimating fair value of stock-based awards using an option pricing model requires input of subjective assumptions, including fair value of the Company’s common stock, and, for stock options, expected term of options and stock price volatility. The Company uses the Black-Scholes option-pricing model to value its stock option awards. The assumptions used in calculating the fair value of stock-based awards represent management’s estimates, involve inherent uncertainties and require application of management’s judgment. As a result, if factors change and management uses different assumptions, stock-based compensation expense could be materially different for future The Company classifies stock-based compensation expense in its statements of operations and comprehensive loss in the same manner in which the award recipient’s payroll costs are classified or in which the award recipient’s service payments are classified.
Comprehensive Income (Loss)	Comprehensive Income (Loss) Comprehensive gain or loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. In 2021 the Company recorded unrealized loss on marketable securities of $0.1 million and in 2020 the company recorded an unrealized gain of less than $0.1 million in other comprehensive income (loss).
Net Loss per Share Attributable to Common Stockholders	Net Loss per Share Attributable to Common Stockholders Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share 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, outstanding stock options are considered to be potentially dilutive securities. Because the Company has reported a net loss for all periods presented, diluted
Income Taxes	Income Taxes Income taxes are recorded using an asset and liability approach. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases using enacted tax rates in effect for the year in which the differences are expected to affect taxable income. Deferred tax assets are reduced by a valuation allowance if current evidence indicates that it is considered more likely than not that these benefits will not be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company’s tax positions are subject to income tax audits. The Company recognizes the tax benefit of an uncertain tax position only if it is more likely than not that the position is sustainable upon examination by the taxing authority, based on the technical merits. The tax benefit recognized is measured as the largest amount of benefit which is more likely than not to be realized upon settlement with the taxing authority. The Company recognizes interest accrued and penalties related to unrecognized tax benefits in its tax provision. The Company evaluates uncertain tax positions on a regular basis. The evaluations are based on a number of factors, including changes in facts and circumstances, changes in tax law, correspondence with tax authorities during the course of the audit, and effective settlement of audit issues. The provision for income taxes includes the effects of any accruals that the Company believes are appropriate, as well as the related net interest and On June 29, 2020 California State Assembly Bill 85 (the “Trailer Bill”) was enacted which suspends the use of California net operating loss (“NOL”) deductions and certain tax credits, including research and development tax credits, for the 2020, 2021, and 2022 tax years.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recently Adopted Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740) Simplifying the Accounting for Income Taxes. ASU 2019-12 New Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) Leases In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326)

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Schedule of Financial Assets Measured and Recognized at Fair Value	As of December 31, 2021, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at December 31, 2021 Quoted Price in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets U.S. government bonds $ 4,667 $ — $ — $ 4,667 Foreign government agency bonds (1) — 6,526 — 6,526 Corporate bonds — 49,989 — 49,989 Asset backed securities — 18,753 — 18,753 Marketable securities 4,667 75,268 — 79,935 Money market funds (2) 15,809 — — 15,809 Total fair value of assets $ 20,476 $ 75,268 $ — $ 95,744 (1) Consists of short-term agency bonds of Asian Development Bank and International Bank for Reconstruction and Development. (2) Included in cash and cash equivalents on the balance sheet. Fair Value Measurements at December 31, 2021 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimate Fair Value Assets U.S. government bonds 4,670 — $ (3 ) 4,667 Foreign government agency bonds (1) 6,530 — (4 ) 6,526 Corporate bonds 50,008 — (19 ) 49,989 Asset backed securities 18,769 — (16 ) 18,753 Marketable securities 79,977 — (42 ) 79,935 Money market funds (2) 15,809 — — 15,809 Total fair value of assets $ 95,786 $ — $ (42 ) $ 95,744 (1) Consists of short-term agency bonds of Asian Development Bank and International Bank for Reconstruction and Development. (2) Included in cash and cash equivalents on the balance sheet. As of December 31, 2020, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at December 31, 2020 Quoted Price in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Corporate bonds $ — $ 31,910 $ — $ 31,910 Marketable securities — 31,910 — 31,910 Money market funds (1) 36,304 — — 36,304 Total fair value of assets $ 36,304 $ 31,910 $ — $ 68,214 (1) Included in cash and cash equivalents on the balance sheet. Fair Value Measurements at December 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimate Fair Value Assets Corporate bonds $ 31,881 $ 30 $ (1 ) $ 31,910 Marketable securities 31,881 30 (1 ) 31,910 Money market funds (1) 36,304 — — 36,304 Total fair value of assets $ 68,185 $ 30 $ (1 ) $ 68,214 (1) Included in cash and cash equivalents on the balance sheet.

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2021
Balance Sheet Related Disclosures [Abstract]
Schedule of Property and Equipment	Property and equipment consisted of the following (in thousands, except years): December 31, Useful Life (In Years) 2021 2020 Furniture and fixtures 3-5 $ 75 $ 63 Leasehold improvements Shorter of useful life or lease term 62 62 Machinery and equipment 6 1,084 933 Tooling 6 974 840 Construction in progress — 5,219 5,008 7,414 6,906 Less: Accumulated depreciation (622 ) (433 ) $ 6,792 $ 6,473
Schedule of Accrued and Other Current Liabilities	Accrued and other current liabilities consisted of the following (in thousands): December 31, 2021 2020 Accrued salaries and benefits $ 2,117 $ 1,330 Accrued research and development expenses 3,396 910 Accrued professional services 361 232 Accrued interest 5 16 Other 64 187 $ 5,943 $ 2,675

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Summary of Future Contractual Maturities of Debt	As of December 31, 2021, the future contractual maturities of debt by fiscal year are as follows (in thousands): 2022 $ 833 Total future maturities of debt $ 833

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments Under Non-cancelable Operating Leases	Future minimum lease payments under non-cancelable operating leases as of December 31, 2021 were as follows (in thousands): Operating Leases 2022 $ 201 Total minimum lease payments $ 201

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2021
Equity [Abstract]
Schedule of Reserved Common Stock on an as-Converted Basis for Future Issuance	The Company had reserved common stock, on an as-converted basis, for future issuance as follows: December 31, 2021 2020 Exercise of outstanding options 3,202,588 3,162,459 Shares of common stock available for grant under the 2019 Plan 1,493,893 844,475 Shares of common stock available for ESPP 477,276 319,054 Total 5,173,757 4,325,988

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Schedule of Activity Under 2019 and 2016 Plan	Activity under the 2019 Plan and 2016 Plan is set forth below: Outstanding Options Shares Available for Grant Number of Shares Weighted Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Balance, January 1, 2020 1,778,044 1,568,874 $ 3.55 8.85 Additional shares authorized 695,281 Options granted (1,669,200 ) 1,669,200 $ 14.56 9.63 Options exercised — (35,265 ) $ 2.34 Options cancelled 40,350 (40,350 ) $ 8.83 Balance, December 31, 2020 844,475 3,162,459 $ 9.31 8.79 Additional shares authorized 697,479 Options granted (129,000 ) 129,000 $ 4.85 9.65 Options exercised — (7,932 ) $ 1.04 Options cancelled 80,939 (80,939 ) $ 9.77 Balance, December 31, 2021 1,493,893 3,202,588 $ 9.14 7.73 Exercisable as of December 31, 2021 1,678,549 $ 8.27 7.04 Vested and expected to vest, December 31, 2021 3,202,588 $ 9.14 7.73
Summary of Stock Based Compensation Expense	Total Year Ended December 31, 2021 2020 Research and development $ 1,777 $ 1,290 General and administrative 3,587 2,728 Total $ 5,364 $ 4,018 The above stock-based compensation expense related to the following equity-based awards: Year Ended December 31, 2021 2020 Stock options $ 5,338 $ 3,989 ESPP 26 29 Total $ 5,364 $ 4,018
2016 Incentive Award Plan
Schedule of Fair Value Assumptions of Stock Options	The Company estimated the fair value of stock options using the Black Scholes option-pricing model. The fair value of stock options was valued using the following assumptions: December 31, 2021 2020 Expected term (years) 5.8 - 6.1 5.5 - 6.1 Expected volatility 91.5%-98.6% 71.2% - 92.5% Risk-free interest rate 0.6%-1.4% 0.3% - 1.7% Dividend yield 0% 0%
2019 Employee Share Purchase Plan
Schedule of Fair Value Assumptions of Stock Options	Compensation expense is calculated using the fair value of the employees' purchase rights under the Black-Scholes option pricing model. December 31, 2021 2020 Expected term (years) 0.5 0.5 Expected volatility 58.8% 111.0% Risk-free interest rate 0.50% 0.1% Dividend yield 0% 0%

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Schedule of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except share and per share data): Year Ended December 31, 2021 2020 Numerator: Net loss attributable to common stockholders $ (51,172 ) $ (47,563 ) Denominator: Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 29,174,386 17,405,688 Net loss per share attributable to common stockholders, basic and diluted $ (1.75 ) $ (2.73 )
Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share	The following outstanding shares of potentially dilutive securities were excluded from the computation of diluted net loss per share attributable to common stockholders for the period presented because including them would have been antidilutive: Year Ended December 31, 2021 2020 Options to purchase common stock 3,202,588 3,162,459 Shares committed under ESPP 33,203 — Total 3,235,791 3,162,459

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Statutory Tax Expense (Benefit) Rate and Effective Tax Expense (Benefit) Rate	The differences between the statutory tax expense (benefit) rate and the effective tax expense (benefit) rate, were as follows (in thousands): Year Ended December 31, 2021 2020 Tax at federal statutory income tax rate $ (10,746 ) $ (9,988 ) Change in valuation allowance 12,877 9,950 Permanent differences 141 (20 ) Prior year true ups — 341 Research and development credits (2,374 ) (154 ) State income taxes (346 ) (128 ) Other 448 — Tax at effective income tax rate $ — $ 1
Components of Net Deferred Tax Assets	Significant components of the Company’s net deferred tax assets are summarized as follows (in thousands): December 31, 2021 2020 Deferred tax assets: Net operating loss carryforwards $ 27,511 $ 17,915 Research and development credit carryforwards 3,514 847 Stock-based compensation 1,189 697 Accruals and other 432 286 Gross deferred tax assets 32,646 19,745 Less: Valuation allowance (32,318 ) (19,441 ) Deferred tax assets, net of valuation allowance 328 304 Deferred tax liabilities: Property and equipment (328 ) (304 ) Net deferred tax assets $ — $ —
Summary of Unrecognized Tax Benefits	The following table summarizes the activity related to the Company’s unrecognized tax benefits: Balance as of January 1, 2020 $ 238 Increase related to current year tax positions 80 Decrease related to prior year tax positions (162 ) Balance as of December 31, 2020 $ 156 Increase related to current year tax positions 213 Increase related to prior year tax positions 38 Balance as of December 31, 2021 $ 407

Organization and Summary of S_3

Organization and Summary of Significant Accounting Policies - Additional Information (Details)	Feb. 26, 2021USD ($)$ / sharesshares	Mar. 31, 2021USD ($)	Dec. 31, 2021USD ($)segmentshares	Dec. 31, 2020USD ($)
Organization And Summary Of Significant Accounting Policies [Line Items]
Proceeds from private placement financing, net of issuance costs			$ 75,215,000
Accumulated deficit			141,736,000	$ 90,564,000
Cash, cash equivalents and marketable securities			$ 95,800,000
Number of operating segment | segment			1
Number of reportable segment | segment			1
Long-lived assets			$ 6,792,000	6,473,000
Impairments of long-lived assets			0	0
Unrealized (loss) gain on marketable securities			$ (71,000)	12,000
ASU 2019-12
Organization And Summary Of Significant Accounting Policies [Line Items]
Change in accounting principle, ASU, adopted [true false]			true
Accounting standards update description			ASU 2019-12
Change in accounting principle, ASU, adoption date			Jan. 1, 2021
Change in accounting principle, ASU, immaterial effect [true false]			true
Minimum
Organization And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets			3 years
Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets			5 years
Unrealized (loss) gain on marketable securities				100,000
United States
Organization And Summary Of Significant Accounting Policies [Line Items]
Long-lived assets			$ 100,000	1,500,000
United Kingdom
Organization And Summary Of Significant Accounting Policies [Line Items]
Long-lived assets				$ 5,000,000
United Kingdom and Europe
Organization And Summary Of Significant Accounting Policies [Line Items]
Long-lived assets			$ 6,700,000
Securities Purchase Agreement
Organization And Summary Of Significant Accounting Policies [Line Items]
Gross proceeds from issuance of common stock	$ 80,000,000
Common Stock
Organization And Summary Of Significant Accounting Policies [Line Items]
Issuance of common stock in private placement financing, net of issuance costs, Shares | shares			14,084,507
Common Stock | Securities Purchase Agreement
Organization And Summary Of Significant Accounting Policies [Line Items]
Issuance of common stock in private placement financing, net of issuance costs, Shares | shares	14,084,507
Shares issued, price per share | $ / shares	$ 5.68
Proceeds from private placement financing, net of issuance costs		$ 75,200,000

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets Measured and Recognized at Fair Value (Details) - Recurring - USD ($) $ in Thousands		Dec. 31, 2021	Dec. 31, 2020
Assets
Marketable Securities		$ 79,935	$ 31,910
Total fair value of assets		95,744	68,214
Marketable Securities Amortized Cost		79,977	31,881
Marketable Securities Gross Unrealized Gains			30
Marketable Securities Gross Unrealized Losses		(42)	(1)
Marketable Securities Estimate Fair Value		79,935	31,910
Amortized Cost		95,786	68,185
Gross Unrealized Gains			30
Gross Unrealized Losses		(42)	(1)
Estimate Fair Value		95,744	68,214
U.S. Government Bonds
Assets
Marketable Securities		4,667
Marketable Securities Amortized Cost		4,670
Marketable Securities Gross Unrealized Losses		(3)
Marketable Securities Estimate Fair Value		4,667
Foreign Government Agency Bonds
Assets
Marketable Securities	[1]	6,526
Marketable Securities Amortized Cost		6,530
Marketable Securities Gross Unrealized Losses		(4)
Marketable Securities Estimate Fair Value		6,526
Corporate Bonds
Assets
Marketable Securities		49,989	31,910
Marketable Securities Amortized Cost		50,008	31,881
Marketable Securities Gross Unrealized Gains			30
Marketable Securities Gross Unrealized Losses		(19)	(1)
Marketable Securities Estimate Fair Value		49,989	31,910
Asset-backed Securities
Assets
Marketable Securities		18,753
Marketable Securities Amortized Cost		18,769
Marketable Securities Gross Unrealized Losses		(16)
Marketable Securities Estimate Fair Value		18,753
Money Market Funds
Assets
Money market funds	[2]	15,809	36,304
Amortized Cost	[2]	15,809	36,304
Estimate Fair Value	[2]	15,809	36,304
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Marketable Securities		4,667
Total fair value of assets		20,476	36,304
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Government Bonds
Assets
Marketable Securities		4,667
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money Market Funds
Assets
Money market funds	[2]	15,809	36,304
Quoted Prices in Active Markets for Identical Assets (Level 2)
Assets
Marketable Securities		75,268	31,910
Total fair value of assets		75,268	31,910
Quoted Prices in Active Markets for Identical Assets (Level 2) | Foreign Government Agency Bonds
Assets
Marketable Securities	[1]	6,526
Quoted Prices in Active Markets for Identical Assets (Level 2) | Corporate Bonds
Assets
Marketable Securities		49,989	$ 31,910
Quoted Prices in Active Markets for Identical Assets (Level 2) | Asset-backed Securities
Assets
Marketable Securities		$ 18,753
[1]	Consists of short-term agency bonds of Asian Development Bank and International Bank for Reconstruction and Development.
[2]	Included in cash and cash equivalents on the balance sheet.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - Recurring - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of financial liabilities measured and recognized	$ 0	$ 0
Fair value of financial assets transfers	0	0
Fair value of financial assets transfers	$ 0	$ 0

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 7,414	$ 6,906
Less: Accumulated depreciation	(622)	(433)
Property and equipment, net	$ 6,792	6,473
Minimum
Property Plant And Equipment [Line Items]
Property and equipment useful life	3 years
Maximum
Property Plant And Equipment [Line Items]
Property and equipment useful life	5 years
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 75	$ 63
Furniture and Fixtures | Minimum
Property Plant And Equipment [Line Items]
Property and equipment useful life	3 years	3 years
Furniture and Fixtures | Maximum
Property Plant And Equipment [Line Items]
Property and equipment useful life	5 years	5 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment useful life	Shorter of useful life or lease term	Shorter of useful life or lease term
Property and equipment, gross	$ 62	$ 62
Machinery and Equipment
Property Plant And Equipment [Line Items]
Property and equipment useful life	6 years	6 years
Property and equipment, gross	$ 1,084	$ 933
Tooling
Property Plant And Equipment [Line Items]
Property and equipment useful life	6 years	6 years
Property and equipment, gross	$ 974	$ 840
Construction in Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 5,219	$ 5,008

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Abstract]
Depreciation expense	$ 393	$ 239

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued salaries and benefits	$ 2,117	$ 1,330
Accrued research and development expenses	3,396	910
Accrued professional services	361	232
Accrued interest	5	16
Other	64	187
Total	$ 5,943	$ 2,675

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details)	Oct. 26, 2018USD ($)$ / sharesshares	Dec. 31, 2021USD ($)Paymentshares	Dec. 31, 2020USD ($)shares
Debt Instrument [Line Items]
Long-term debt net of debt discount and issuance costs		$ 833,000
Loan Agreement | Silicon Valley Bank
Debt Instrument [Line Items]
Debt instrument, maximum borrowing capacity	$ 10,000,000
Debt instrument, floating interest rate percentage	6.50%
Debt instrument, interest rate increase percentage	5.00%
Debt instrument, maturity date	May 1, 2022
Debt instrument, final principal payment description		a final payment equal to the original principal amount of the Term Loans multiplied by 5.0% is due on the earliest to occur of (a) May 1, 2022 or (b) the prepayment in full of the term loan advances.
Debt instrument, final payment percentage of original principal		5.00%
Number of shares to be called by warrants issued | shares	10,232
Warrants, exercise price | $ / shares	$ 1.04
Warrants, term	10 years
Common stock warrants outstanding | shares		0	0
Debt issuance cost final payment recognized as additional interest expense		$ 300,000
Accrued liabilities related to accretion of final payment included in long-term debt		$ 200,000	$ 200,000
Loan Agreement | Silicon Valley Bank | Maximum
Debt Instrument [Line Items]
Fair value of warrants	$ 100,000
Loan Agreement | Silicon Valley Bank | If Prepayment Made Prior to October 26, 2019
Debt Instrument [Line Items]
Debt instrument, percentage of prepayment premium		3.00%
Loan Agreement | Silicon Valley Bank | If Prepayment Made After October 26, 2019 But Before October 26, 2020
Debt Instrument [Line Items]
Debt instrument, percentage of prepayment premium		2.00%
Loan Agreement | Silicon Valley Bank | If Prepayment Made After October 26, 2020 But Before May 1, 2020
Debt Instrument [Line Items]
Debt instrument, percentage of prepayment premium		1.00%
Loan Agreement | Silicon Valley Bank | Greater above Prime Rate
Debt Instrument [Line Items]
Debt instrument, floating interest rate percentage	1.50%
Loan Agreement | Silicon Valley Bank | Term A Loan
Debt Instrument [Line Items]
Debt instrument, current borrowing capacity	$ 5,000,000
Debt instrument, principal repayments commencing date		Dec. 1, 2019
Debt instrument, number of monthly principal payments | Payment		30
Long-term debt net of debt discount and issuance costs		$ 1,100,000
Debt instrument, term		3 years 7 months 6 days
Debt issuance costs		$ 100,000
Loan Agreement | Silicon Valley Bank | Term A Loan | Maximum
Debt Instrument [Line Items]
Amortization of debt discount		$ 100,000
Loan Agreement | Silicon Valley Bank | Term Loans
Debt Instrument [Line Items]
Debt instrument, remaining borrowing capacity, no longer available for draw	$ 5,000,000

Long-Term Debt - Summary of Fut

Long-Term Debt - Summary of Future Contractual Maturities of Debt (Details) $ in Thousands	Dec. 31, 2021USD ($)
Debt Disclosure [Abstract]
2022	$ 833
Total future maturities of debt	$ 833

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	Jul. 31, 2019	Jan. 09, 2018	Feb. 28, 2022	Oct. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Lessee Lease Description [Line Items]
Operating lease, expense					$ 0.3	$ 0.3
Accrued and Other Current Liabilities | Maximum
Lessee Lease Description [Line Items]
Operating lease deferred rent					$ 0.1
California
Lessee Lease Description [Line Items]
Operating lease expiration date		Apr. 30, 2021		Oct. 31, 2022
Operating lease, option to extend		extend it through October 31, 2021		extended the lease term through October 31, 2022
Operating Lease, existence of option to extend		true		true
North Carolina
Lessee Lease Description [Line Items]
Operating lease expiration date	Jul. 31, 2022
Operating lease, term of contract	3 years
North Carolina | Subsequent Event
Lessee Lease Description [Line Items]
Operating lease expiration date			Jul. 31, 2025
Operating lease, option to extend			extend the lease term through July 31, 2025
Operating Lease, existence of option to extend			true

Commitments and Contingencies_2

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Non-cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2021USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2022	$ 201
Total minimum lease payments	$ 201

Preferred Stock - Additional In

Preferred Stock - Additional Information (Details) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Equity [Abstract]
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Equity [Abstract]
Common stock, shares authorized	300,000,000	300,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, voting rights	one vote for each share

Common Stock - Schedule of Rese

Common Stock - Schedule of Reserved Common Stock on an as-Converted Basis for Future Issuance (Details) - shares	Dec. 31, 2021	Dec. 31, 2020
Class Of Stock [Line Items]
Exercise of outstanding options	3,202,588	3,162,459
Total	5,173,757	4,325,988
2019 Incentive Award Plan
Class Of Stock [Line Items]
Shares of common stock available for grant	1,493,893	844,475
ESPP
Class Of Stock [Line Items]
Shares of common stock available for grant	477,276	319,054

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend rate		0.00%	0.00%
Common stock, shares reserved for issuance		5,173,757	4,325,988
Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend rate		0.00%
2016 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options term		10 years
Options and restricted stock awards vesting period		4 years
Aggregate intrinsic value of options vested and expected to vest		$ 2,200,000	$ 1,900,000
Aggregate intrinsic value of options exercised			$ 800,000
Weighted average grant-date fair value of options granted		$ 3.66	$ 9.62
Unrecognized stock-based compensation expense		$ 9,600,000
Unrecognized stock-based compensation expense, weighted-average recognition period		2 years 2 months 12 days
Fair value of options vested		$ 5,300,000	$ 4,000,000
2016 Incentive Award Plan | Incentive Stock Options | 10% Stockholder
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Estimated fair value shares date of grant, maximum		10.00%
2016 Incentive Award Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price, percent of estimated fair value of shares on date of grant		100.00%
2016 Incentive Award Plan | Minimum | Incentive Stock Options | 10% Stockholder
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Exercise price, percent of estimated fair value of shares on date of grant		110.00%
2016 Incentive Award Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate intrinsic value of options exercised		$ 100,000
2016 Incentive Award Plan | Maximum | 10% Stockholder
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options term		5 years
2019 Incentive Award Plan | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in number of common stock shares available for Issuance	1,261,822
2019 Employee Share Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense, weighted-average recognition period		6 months
Expected dividend rate		0.00%	0.00%
Common stock, shares reserved for issuance		477,276		160,000
Maximum percentage of base compensation permitted to acquire common stock through payroll		15.00%
Maximum number of shares permitted to acquire through payroll		50,000
Maximum values of shares permitted to acquire through payroll		$ 25,000
Fair market value percentage available to employees		85.00%
Employee share purchase plan offering period		6 months 15 days
Employee share purchase plan second offering period		5 months 15 days
Shares issued in first offering period		16,147	14,766
2019 Employee Share Purchase Plan | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares reserved for issuance	315,455
2019 Employee Share Purchase Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense		$ 100,000

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Activity Under 2019 Plan and 2016 Plan (Details) - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding Options, Number of Shares, Beginning Balance	3,162,459
Outstanding Options, Number of Shares, Ending Balance	3,202,588	3,162,459
2019 and 2016 Incentive Award Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Available for Grant, Beginning Balance	844,475	1,778,044
Shares Available for Grant, Additional shares authorized	697,479	695,281
Shares Available for Grant, Options granted	(129,000)	(1,669,200)
Shares Available for Grant, Options cancelled	80,939	40,350
Shares Available for Grant, Ending Balance	1,493,893	844,475	1,778,044
Outstanding Options, Number of Shares, Beginning Balance	3,162,459	1,568,874
Outstanding Options, Number of Shares, Options granted	129,000	1,669,200
Outstanding Options, Number of Shares, Options exercised	(7,932)	(35,265)
Outstanding Options, Number of Shares, Options cancelled	(80,939)	(40,350)
Outstanding Options, Number of Shares, Ending Balance	3,202,588	3,162,459	1,568,874
Outstanding Options, Number of Shares, Exercisable as of December 31, 2021	1,678,549
Outstanding Options, Number of Shares, Vested and expected to vest, December 31, 2021	3,202,588
Outstanding Options, Weighted Average Exercise Price, Beginning Balance	$ 9.31	$ 3.55
Outstanding Options, Weighted Average Exercise Price, Options granted	4.85	14.56
Outstanding Options, Weighted Average Exercise Price, Options exercised	1.04	2.34
Outstanding Options, Weighted Average Exercise Price, Options cancelled	9.77	8.83
Outstanding Options, Weighted Average Exercise Price, Ending Balance	9.14	$ 9.31	$ 3.55
Shares Available for Grant, Exercisable as of December 31, 2021	8.27
Shares Available for Grant, Vested and expected to vest, December 31, 2021	$ 9.14
Weighted Average Remaining Contractual Term, Balance	7 years 8 months 23 days	8 years 9 months 14 days	8 years 10 months 6 days
Weighted Average Remaining Contractual Term, Options granted	9 years 7 months 24 days	9 years 7 months 17 days
Weighted Average Remaining Contractual Term, Exercisable as of December 31, 2021	7 years 14 days
Weighted Average Remaining Contractual Term, Vested and expected to vest, December 31, 2021	7 years 8 months 23 days

Stock-based Compensation - Sc_2

Stock-based Compensation - Schedule of Fair Value Assumptions of Stock Options (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, Minimum	91.50%	71.20%
Expected volatility, Maximum	98.60%	92.50%
Risk-free interest rate, Minimum	0.60%	0.30%
Risk-free interest rate, Maximum	1.40%	1.70%
Dividend yield	0.00%	0.00%
2019 Employee Share Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 months	6 months
Expected volatility	58.80%	111.00%
Risk-free interest rate	0.50%	0.10%
Dividend yield	0.00%	0.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 9 months 18 days	5 years 6 months
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 years 1 month 6 days	6 years 1 month 6 days

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 5,364	$ 4,018
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,777	1,290
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 3,587	$ 2,728

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Stock Based Compensation Expense Related to Equity Based Awards (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 5,364	$ 4,018
Stock Options
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	5,338	3,989
ESPP
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 26	$ 29

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Schedule of Computation of Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net loss attributable to common stockholders	$ (51,172)	$ (47,563)
Denominator:
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	29,174,386	17,405,688
Net loss per share attributable to common stockholders, basic and diluted	$ (1.75)	$ (2.73)

Net Loss Per Share Attributab_4

Net Loss Per Share Attributable to Common Stockholders - Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding	3,235,791	3,162,459
Shares Committed Under ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding	33,203
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding	3,202,588	3,162,459

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Provision for income taxes	$ 0	$ 0
Percentage of cumulative ownership changes	50.00%
Unrecognized tax benefits	$ 407,000	$ 156,000		$ 238,000
Unrecognized tax benefits would affect the company's effective tax rate	0
Interest related to unrecognized tax benefits	0
Penalties related to unrecognized tax benefits	0
Federal
Income Taxes [Line Items]
Net operating loss carryforwards	130,400,000		$ 4,700,000		$ 125,700,000
Operating loss carryforwards begin to expire			2036
Operating loss carryforwards offset of taxable income percentage			100.00%
Operating loss carryforwards limitation rate on taxable income		80.00%
Tax credit carryforwards	$ 3,300,000
Tax credit carryforward, expiration year	2037
Federal | Research and Development
Income Taxes [Line Items]
Tax credit carryforwards	$ 1,200,000
State
Income Taxes [Line Items]
Net operating loss carryforwards	$ 2,900,000
Operating loss carryforwards begin to expire	2036
State | California | Research and Development
Income Taxes [Line Items]
Tax credit carryforwards	$ 800,000

Income Taxes - Schedule of Stat

Income Taxes - Schedule of Statutory Tax Expense (Benefit) Rate and Effective Tax Expense (Benefit) Rate (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Tax at federal statutory income tax rate	$ (10,746,000)	$ (9,988,000)
Change in valuation allowance	12,877,000	9,950,000
Permanent differences	141,000	(20,000)
Prior year true ups		341,000
Research and development credits	(2,374,000)	(154,000)
State income taxes	(346,000)	(128,000)
Other	448,000
Tax at effective income tax rate	$ 0	$ 0

Income Taxes - Components of Ne

Income Taxes - Components of Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Net operating loss carryforwards	$ 27,511	$ 17,915
Research and development credit carryforwards	3,514	847
Stock-based compensation	1,189	697
Accruals and other	432	286
Gross deferred tax assets	32,646	19,745
Less: Valuation allowance	(32,318)	(19,441)
Deferred tax assets, net of valuation allowance	328	304
Deferred tax liabilities:
Property and equipment	$ (328)	$ (304)

Income Taxes - Summary of Unrec

Income Taxes - Summary of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Beginning balance	$ 156	$ 238
Increase related to current year tax positions	213	80
Decrease related to prior year tax positions		(162)
Increase related to prior year tax positions	38
Ending balance	$ 407	$ 156

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021USD ($)Stockholdershares	Dec. 31, 2020USD ($)
Related Party Transaction [Line Items]
Issuance of common stock upon initial public offering,net of issuance cost	$ 75,215,000
SNBL
Related Party Transaction [Line Items]
Due to related party	0	$ 0
SNBL | Research and Development
Related Party Transaction [Line Items]
Preclinical study services expenses	$ 0
SNBL | Maximum | Research and Development
Related Party Transaction [Line Items]
Preclinical study services expenses		$ 100,000
Two Existing Stockholders Affiliated with Directors
Related Party Transaction [Line Items]
Number of existing stockholders of company affiliated directors purchased common stock | Stockholder	2
Issuance of common stock in private placement financing, net of issuance costs, Shares | shares	2,464,788
Issuance of common stock upon initial public offering,net of issuance cost	$ 14,000,000