Satsuma Pharmaceuticals (STSA) 10-Q 12 May 20 2020 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2020	Apr. 30, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Registrant Name	Satsuma Pharmaceuticals, Inc.
Entity Central Index Key	0001692830
Entity Current Reporting Status	Yes
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
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 Quarterly Report	true
Document Transition Report	false
Title of 12(b) Security	Common stock, par value $0.0001
Trading Symbol	STSA
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		17,389,447

Condensed Balance Sheets (Unaud

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 22,903	$ 22,755
Short-term marketable securities	77,877	84,942
Prepaid expenses and other current assets	8,099	7,047
Total current assets	108,879	114,744
Property and equipment, net	1,031	832
Long-term marketable securities	3,339	10,203
Other non-current assets	467	497
Total assets	113,716	126,276
Liabilities
Accounts payable	3,438	4,282
Accrued and other current liabilities	1,813	1,710
Current portion of long-term debt	1,982	1,979
Total current liabilities	7,233	7,971
Long-term debt	2,478	2,951
Other noncurrent liabilities	15	19
Total liabilities	9,726	10,941
Commitments and Contingencies (Note 9)
Stockholders’ equity
Common stock, $0.0001 par value, 300,000,000 shares authorized as of March 31, 2020 and December 31, 2019, respectively; 17,386,247 shares and 17,382,047 shares issued and outstanding as of March 31, 2020 and December 31, 2019	2	2
Additional paid-in-capital	158,777	158,317
Accumulated other comprehensive (loss) income	(15)	17
Accumulated deficit	(54,774)	(43,001)
Total stockholders’ equity	103,990	115,335
Total liabilities and stockholders’ equity	$ 113,716	$ 126,276

Condensed Balance Sheets (Una_2

Condensed Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
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	17,386,247	17,382,047
Common stock, shares outstanding	17,386,247	17,382,047

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating expenses
Research and development	$ 9,648	$ 2,150
General and administrative	2,523	564
Total operating expenses	12,171	2,714
Loss from operations	(12,171)	(2,714)
Interest income	502	21
Interest expense	(104)	(122)
Net loss	(11,773)	(2,815)
Unrealized loss on marketable securities	(32)
Comprehensive loss	$ (11,805)	$ (2,815)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.68)	$ (2.51)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	17,383,016	1,123,219

Condensed Statements of Convert

Condensed Statements of Convertible Preferred Stock and Stockholders Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2018	$ (12,132)		$ 1	$ 2,693		$ (14,826)
Temporary equity, Beginning balance, Shares at Dec. 31, 2018		3,046,355
Temporary equity, Beginning balance at Dec. 31, 2018		$ 11,648
Beginning balance, Shares at Dec. 31, 2018			1,083,280
Issuance of common stock upon exercise of stock options	53			53
Issuance of common stock upon exercise of stock options, Shares			53,721
Vesting of restricted stock, Shares			7,979
Stock-based compensation	54			54
Net loss	(2,815)					(2,815)
Ending balance at Mar. 31, 2019	(14,840)		$ 1	2,800		(17,641)
Temporary equity, Ending balance, Shares at Mar. 31, 2019		3,046,355
Temporary equity, Ending balance at Mar. 31, 2019		$ 11,648
Ending Balance, Shares at Mar. 31, 2019			1,144,980
Beginning balance at Dec. 31, 2019	115,335		$ 2	158,317	$ 17	(43,001)
Beginning balance, Shares at Dec. 31, 2019			17,382,047
Issuance of common stock upon exercise of stock options	11			11
Issuance of common stock upon exercise of stock options, Shares			4,200
Stock-based compensation	449			449
Net loss	(11,773)					(11,773)
Other comprehensive loss	(32)				(32)
Ending balance at Mar. 31, 2020	$ 103,990		$ 2	$ 158,777	$ (15)	$ (54,774)
Ending Balance, Shares at Mar. 31, 2020			17,386,247

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities
Net loss	$ (11,773)	$ (2,815)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation	49	31
Non-cash interest expense, and amortization of debt discount and issuance costs	30	29
Net amortization of premiums and accretion of discounts on marketable securities	(40)
Stock-based compensation	449	54
Changes in assets and liabilities
Prepaid expenses and other assets	(1,022)	(546)
Accounts payable	(809)	913
Accrued and other current liabilities	103	(724)
Other non-current liabilities	(4)	(2)
Net cash used in operating activities	(13,017)	(3,060)
Cash flows from investing activities
Purchases of marketable securities	(5,331)
Proceeds from maturities of available-for-sale securities	19,268
Purchases of property and equipment	(283)	(22)
Net cash provided by (used in) investing activities	13,654	(22)
Cash flows from financing activities
Repayment of debt	(500)
Proceeds from exercise of common stock options	11	53
Net cash (used in) provided by financing activities	(489)	53
Net increase (decrease) in cash and cash equivalents	148	(3,029)
Cash and cash equivalents
Cash and cash equivalents, at beginning of period	22,755	5,205
Cash and cash equivalents, at end of period	22,903	2,176
Supplemental disclosure of cash flow information:
Cash paid for interest	77	$ 87
Supplemental non-cash investing and financing activities:
Purchases of property and equipment in accounts payable	$ 35

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2020
Accounting Policies [Abstract]
Organization and Summary of significant Accounting Policies	Note 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. Initial Public Offering On September 12, 2019, the Company’s registration statement on Form S-1 (File No. 333-233347) relating to its initial public offering (“IPO”) of common stock became effective. The IPO closed on September 17, 2019 at which time the Company issued 5,500,000 shares of its common stock at a price of $15.00 per share, which did not include the issuance of any shares in connection with the exercise by the underwriters of their option to purchase up to 825,000 additional shares. The Company received an aggregate of $82.5 million gross proceeds, before underwriting discounts, commissions and offering costs. 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 currently under development and will require significant additional development efforts as the Company continues the development of, and seek regulatory approvals for, STS101 and begin to commercialize it, if approved. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance and reporting. There can be no assurance that the Company’s development of STS101 will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained or maintained, that STS101 will obtain necessary government regulatory approval or that STS will be commercially viable, if approved. Even if STS101 development efforts are successful, it is uncertain when, if ever, the Company will generate revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from other pharmaceutical and biopharmaceutical companies. The extent of the impact of COVID-19 on the Company's operational and financial performance will depend on certain developments, including the duration and spread of the outbreak and the impact on the Company's clinical trials, employees and vendors. At this point, the degree to which COVID-19 may impact the Company's financial condition or results of operations is uncertain. A prolonged outbreak could have a material adverse impact on financial results and business operations of the Company, including the timing and ability of Company to complete certain clinical trials and other efforts required to advance the development of its drug candidates and raise additional capital. In addition, the Company is dependent upon the services of its employees, consultants and other third parties. The Company has incurred significant losses and negative cash flows from operations in all periods since its inception and had an accumulated deficit of $54.8 million as of March 31, 2020. The Company has historically financed its operations primarily through private placements of convertible preferred stock, a convertible promissory note, long-term debt and sale of common stock in the IPO. 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, raise additional capital or reduce certain discretionary spending would have a material adverse effect on the Company’s ability to achieve its intended business objectives. As of March 31, 2020, the Company had cash, cash equivalents and marketable securities of $104.1 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 unaudited interim condensed financial statements as of and for the three months ended March 31, 2020 and through the end of 2021. Basis of Presentation The unaudited interim condensed financial statements and accompanying notes have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”). Unaudited Interim Financial Information The accompanying balance sheet as of March 31, 2020, the statements of operations and comprehensive loss, the statements of convertible preferred stock and stockholders’ equity (deficit), and statements of cash flows for the three months ended March 31, 2020 and 2019 are unaudited. The unaudited interim condensed financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2020 and the results of its operations and its cash flows for the three months ended March 31, 2020 and 2019. The financial data and other information disclosed in these notes related to the three months ended March 31, 2020 and 2019 are also unaudited. The results for the three months ended March 31, 2020 are not necessarily indicative of results to be expected for the year ending December 31, 2020, any other interim periods, or any future year or period. The balance sheet as of December 31, 2019 included herein was derived from the audited financial statements as of that date. Certain disclosures have been condensed or omitted from the unaudited interim condensed financial statements. The accompanying interim unaudited condensed financial statements should be read in conjunction with the audited financial statements and the related notes thereto for the year ended December 31, 2019, which are included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2019 filed with the Securities and Exchange Commission, or the SEC, on March 10, 2020. Use of Estimates The preparation of unaudited interim condensed 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 unaudited interim condensed financial statements and the reported amounts of income and expenses during the reporting period. Such estimates include the accrual of research and development expenses, deferred tax assets, 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 and adjust those estimates and assumptions when facts and circumstances dictate. The inputs into management’s accounting estimates consider the economic impact of the outbreak of COVID-19. The extent to which the COVID-19 further affects our financial statements will depend on future developments, which are highly uncertain and are difficult to predict, including, but not limited to, the duration and spread of COVID-19, its severity, the actions to contain the virus or treat its impact, and how quickly and to what extent normal economic and operating conditions can resume. Accordingly, actual results could differ from those estimates and assumptions. 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 short-term 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. 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. Accumulated depreciation as of March 31, 2020 and December 31, 2019 was $0.2 million. 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, convertible preferred stock, convertible preferred stock tranche liability, obligation to issue additional common stock, convertible note, stock options and common stock subject to repurchase related to unvested restricted stock awards are considered to be potentially dilutive securities. Basic and diluted net loss per share attributable to common stockholders are presented in conformity with the two-class method required for participating securities as the convertible preferred stock is considered a participating security because it participates in dividends with common stock. The holders of convertible preferred stock do not have a contractual obligation to share in the Company’s losses. As such, the net loss was attributed entirely to common stockholders. Because the Company has reported a net loss for all periods presented, diluted net loss per common share is the same as basic net loss per common share for those periods. Income Taxes On March 18, 2020, the Families First Coronavirus Response Act (“FFCR Act”), and on March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) were each enacted in response to the COVID-19 pandemic. The FFCR Act and the CARES Act contain numerous tax-related provisions relating to refundable payroll tax credits, deferment of employer side social security payments, net operating loss carryback periods, alternative minimum tax credit refunds, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. The FFCR Act and CARES Act did not have a material impact on the Company’s unaudited condensed financial statements as of March 31, 2020; however, the Company continues to examine the impacts the FFCR Act and CARES Act may have on its business, results of operations, financial condition and liquidity. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) under its accounting standard codifications (“ASC”) or other standard setting bodies and adopted by the Company as of the specified effective date, unless otherwise discussed below. Recently Adopted Accounting Pronouncements In August 2018, the FASB issued ASU No.2018-13 (Topic 820), Fair Value Measurement. ASU 2018-13 modifies the disclosure requirements on fair value measurement in Topic 820. For public entities, ASU 2018-13 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted. The Company adopted this ASU on January 1, 2020. The adoption of this standard did not have a material impact on the Company’s financial statements. New Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) Codification Improvements to Topic 842, Leases and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements Leases (Topic 842) Codification Improvements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326)

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2020
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 unaudited interim condensed 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 March 31, 2020, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at March 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 U.S. government bonds $ 10,043 $ — $ — $ 10,043 Corporate bonds — 50,104 — 50,104 Asset backed securities — 21,084 — 21,084 Marketable Securities 10,043 71,188 — 81,231 Money market funds (1) 22,879 — — 22,879 Total fair value of assets $ 32,922 $ 71,188 $ — $ 104,110 (1) Included in cash and cash equivalents on the balance sheet. Fair Value Measurements at March 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimate Fair Value Assets U.S. government bonds $ 10,043 $ 83 $ — $ 10,126 Corporate bonds 50,104 — (64 ) 50,040 Asset backed securities 21,084 2 (36 ) 21,050 Marketable securities 81,231 85 (100 ) 81,216 Money market funds (1) 22,879 — — 22,879 Total fair value of assets $ 104,110 $ 85 $ (100 ) $ 104,095 (1) Included in cash and cash equivalents on the balance sheet. As of December 31, 2019, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at December 31, 2019 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 $ 10,062 $ — $ — $ 10,062 Overnight repurchase agreements (1) 14,000 — — 14,000 Corporate bonds — 64,285 — 64,285 Asset backed securities — 20,781 — 20,781 Marketable securities 24,062 85,066 — 109,128 Money market funds (1) 8,730 — — 8,730 Total fair value of assets $ 32,792 $ 85,066 $ — $ 117,858 (1) Included in cash and cash equivalents on the balance sheet. Fair Value Measurements at December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimate Fair Value Assets U.S. government bonds $ 10,062 $ 1 $ — $ 10,063 Overnight repurchase agreements (1) 14,000 — — 14,000 Corporate bonds 64,285 17 (7 ) 64,295 Asset backed securities 20,781 7 (1 ) 20,787 Marketable securities 109,128 25 (8 ) 109,145 Money market funds (1) 8,730 — — 8,730 Total fair value of assets $ 117,858 $ 25 $ (8 ) $ 117,875 (1) Included in cash and cash equivalents on the balance sheet. There were no financial liabilities measured and recognized at fair value as of March 31, 2020 and December 31, 2019.

Accrued and Other Current Liabi

Accrued and Other Current Liabilities	3 Months Ended
	Mar. 31, 2020
Payables And Accruals [Abstract]
Accrued and Other Current Liabilities	3. Accrued and Other Current Liabilities Accrued and other current liabilities consisted of the following (in thousands): March 31, December 31, 2020 2019 Accrued salaries and benefits $ 555 $ 1,145 Accrued research and development expenses 827 88 Accrued professional services 327 248 Accrued interest 24 27 Other 80 202 Total $ 1,813 $ 1,710

Convertible Preferred Stock

Convertible Preferred Stock	3 Months Ended
	Mar. 31, 2020
Equity [Abstract]
Convertible Preferred Stock	4. Convertible Preferred Stock In April 2019, the Company issued 6,889,986 shares of its Series B convertible preferred stock at $8.95444 per share to certain investors for gross proceeds of $61.7 million. Following the closing of the IPO, all outstanding shares of the redeemable convertible preferred stock converted into 9,936,341 shares of common stock and the related carrying value was reclassified to common stock and additional paid-in capital. There were no shares of redeemable convertible preferred stock outstanding as of March 31, 2020 and December 31,2019.

Long-Term Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Long-Term Debt	5 . 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 provides 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 (the “Term B Loan” and together with the Term A Loan, the “Term Loans”) is available for draw down by the Company in $1.0 million increments. 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. As of March 31, 2020, the future contractual maturities of debt by fiscal year are as follows (in thousands): 2020 (remaining nine months) $ 1,500 2021 2,000 2022 833 Total future maturities of debt $ 4,333 As of March 31, 2020, the term loan advances, net of debt discount and debt issuance costs, were $4.5 million and are included in current portion of long-term debt and long-term debt on the Company’s condensed balance sheet. 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 $0.1 million as of March 31, 2020 and December 31, 2019, respectively, included in long-term debt on the Company’s condensed balance sheet.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	6. Stock-Based Compensation 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 may include continued service, performance and/or other conditions. Generally, options and restricted stock awards vest over a four-year period. In January 2020, the number of shares of common stock available for issuance under the 2019 Plan was increased by 695,281 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 (574,700 ) 574,700 $ 28.71 9.93 Options exercised — (4,200 ) $ 2.64 Balance, March 31, 2020 1,898,625 2,139,374 $ 10.31 8.96 Exercisable as of March 31, 2020 566,730 Vested and expected to vest, March 31, 2020 2,139,374 The weighted-average grant-date fair value of options granted during the three months ended March 31, 2020 and 2019 was $17.04 and $3.20 per share, respectively. As of March 31, 2020, the total unrecognized stock-based compensation expense for stock options was $12.4 million, which is expected to be recognized over a weighted-average period of 3.1 years. The total fair value of options vested for the three months ended March 31, 2020 and 2019 was $0.3 million and less than $0.1 million, respectively. The Company accounts for forfeitures as they occur. Stock-Based Compensation Associated with Awards to Employees and Non-employees During the three months ended March 31, 2020 and 2019, the Company granted stock options to employees and non-employees to purchase 574,700 and 110,637 shares of common stock, respectively. 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 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 offering period and purchase period will be determined by the Board of Directors. As of March 31, 2020, 333,820 shares under the ESPP remain available for purchase and no offerings had been authorized. Stock-Based Compensation Expense Total stock-based compensation expense recorded related to options granted to employees and non-employees was as follows (in thousands): Three Months Ended March 31, 2020 2019 Research and development $ 185 $ 21 General and administrative 264 33 $ 449 $ 54

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	3 Months Ended
	Mar. 31, 2020
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	7. 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): Three Months Ended March 31, 2020 2019 Numerator: Net loss attributable to common stockholders $ (11,773 ) $ (2,815 ) Denominator: Weighted-average shares outstanding 17,383,016 1,151,145 Less: weighted-average unvested restricted shares and shares subject to repurchase — (27,926 ) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 17,383,016 1,123,219 Net loss per share attributable to common stockholders, basic and diluted $ (0.68 ) $ (2.51 ) 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: Three Months Ended March 31, 2020 2019 Options to purchase common stock 2,139,374 886,690 Unvested restricted common stock awards — 23,936 Warrants to purchase common stock 5,116 10,232 Convertible preferred stock — 3,046,355 Total 2,144,490 3,967,213

Related Party Transaction

Related Party Transaction	3 Months Ended
	Mar. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	8. Related Party Transactions In April 2019, as part of the Company’s Series B Financing, SNBL purchased 307,110 shares of Series B convertible preferred stock with an aggregate purchase price of $2.7 million. SNBL purchased 233,333 shares of the common stock upon IPO, in addition to the conversion of its 33,741 shares of outstanding Series A preferred stock into the common stock. Transactions with Others Upon the closing of the IPO in September 2019, 3,887,668 shares of outstanding Series A and Series B convertible preferred stock owed by two shareholders of the Company, each owning more than 10% of the Company’s equity on an as-converted basis, converted into 3,887,668 shares of common stock. Upon the IPO these shareholders also purchased additional 2,633,333 shares of the Company’s common stock, with an aggregate purchase price of $39.5 million.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2020
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Operating Leases Future minimum lease payments under non-cancelable operating leases as of March 31, 2020 were as follows (in thousands): Operating Leases 2020 (remaining nine months) $ 225 2021 195 2022 83 Total minimum lease payments $ 503

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes For the three months ended March 31, 2020 and 2019, the Company did not record an income tax provision. The U.S. federal and California deferred tax assets generated from the Company’s net operating losses have been fully reserved, as the Company believes it is more likely than not the benefit will not be realized.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	11 . Subsequent Events For the purposes of the interim financial statements as of March 31, 2020 and for the three months ended, the Company has evaluated the subsequent events through May 12, 2020, the date the unaudited interim condensed financial statements were issued.

Organization and Summary of S_2

Organization and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2020
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.
Initial Public Offering	Initial Public Offering On September 12, 2019, the Company’s registration statement on Form S-1 (File No. 333-233347) relating to its initial public offering (“IPO”) of common stock became effective. The IPO closed on September 17, 2019 at which time the Company issued 5,500,000 shares of its common stock at a price of $15.00 per share, which did not include the issuance of any shares in connection with the exercise by the underwriters of their option to purchase up to 825,000 additional shares. The Company received an aggregate of $82.5 million gross proceeds, before underwriting discounts, commissions and offering costs.
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 currently under development and will require significant additional development efforts as the Company continues the development of, and seek regulatory approvals for, STS101 and begin to commercialize it, if approved. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance and reporting. There can be no assurance that the Company’s development of STS101 will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained or maintained, that STS101 will obtain necessary government regulatory approval or that STS will be commercially viable, if approved. Even if STS101 development efforts are successful, it is uncertain when, if ever, the Company will generate revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from other pharmaceutical and biopharmaceutical companies. The extent of the impact of COVID-19 on the Company's operational and financial performance will depend on certain developments, including the duration and spread of the outbreak and the impact on the Company's clinical trials, employees and vendors. At this point, the degree to which COVID-19 may impact the Company's financial condition or results of operations is uncertain. A prolonged outbreak could have a material adverse impact on financial results and business operations of the Company, including the timing and ability of Company to complete certain clinical trials and other efforts required to advance the development of its drug candidates and raise additional capital. In addition, the Company is dependent upon the services of its employees, consultants and other third parties. The Company has incurred significant losses and negative cash flows from operations in all periods since its inception and had an accumulated deficit of $54.8 million as of March 31, 2020. The Company has historically financed its operations primarily through private placements of convertible preferred stock, a convertible promissory note, long-term debt and sale of common stock in the IPO. 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, raise additional capital or reduce certain discretionary spending would have a material adverse effect on the Company’s ability to achieve its intended business objectives. As of March 31, 2020, the Company had cash, cash equivalents and marketable securities of $104.1 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 unaudited interim condensed financial statements as of and for the three months ended March 31, 2020 and through the end of 2021.
Basis of Presentation	Basis of Presentation The unaudited interim condensed financial statements and accompanying notes have been prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”).
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying balance sheet as of March 31, 2020, the statements of operations and comprehensive loss, the statements of convertible preferred stock and stockholders’ equity (deficit), and statements of cash flows for the three months ended March 31, 2020 and 2019 are unaudited. The unaudited interim condensed financial statements have been prepared on the same basis as the audited annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2020 and the results of its operations and its cash flows for the three months ended March 31, 2020 and 2019. The financial data and other information disclosed in these notes related to the three months ended March 31, 2020 and 2019 are also unaudited. The results for the three months ended March 31, 2020 are not necessarily indicative of results to be expected for the year ending December 31, 2020, any other interim periods, or any future year or period. The balance sheet as of December 31, 2019 included herein was derived from the audited financial statements as of that date. Certain disclosures have been condensed or omitted from the unaudited interim condensed financial statements. The accompanying interim unaudited condensed financial statements should be read in conjunction with the audited financial statements and the related notes thereto for the year ended December 31, 2019, which are included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2019 filed with the Securities and Exchange Commission, or the SEC, on March 10, 2020.
Use of Estimates	Use of Estimates The preparation of unaudited interim condensed 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 unaudited interim condensed financial statements and the reported amounts of income and expenses during the reporting period. Such estimates include the accrual of research and development expenses, deferred tax assets, 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 and adjust those estimates and assumptions when facts and circumstances dictate. The inputs into management’s accounting estimates consider the economic impact of the outbreak of COVID-19. The extent to which the COVID-19 further affects our financial statements will depend on future developments, which are highly uncertain and are difficult to predict, including, but not limited to, the duration and spread of COVID-19, its severity, the actions to contain the virus or treat its impact, and how quickly and to what extent normal economic and operating conditions can resume. Accordingly, actual results could differ from those estimates and assumptions.
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 short-term 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.
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. Accumulated depreciation as of March 31, 2020 and December 31, 2019 was $0.2 million.
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, convertible preferred stock, convertible preferred stock tranche liability, obligation to issue additional common stock, convertible note, stock options and common stock subject to repurchase related to unvested restricted stock awards are considered to be potentially dilutive securities. Basic and diluted net loss per share attributable to common stockholders are presented in conformity with the two-class method required for participating securities as the convertible preferred stock is considered a participating security because it participates in dividends with common stock. The holders of convertible preferred stock do not have a contractual obligation to share in the Company’s losses. As such, the net loss was attributed entirely to common stockholders. Because the Company has reported a net loss for all periods presented, diluted net loss per common share is the same as basic net loss per common share for those periods.
Income Taxes	Income Taxes On March 18, 2020, the Families First Coronavirus Response Act (“FFCR Act”), and on March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (“CARES Act”) were each enacted in response to the COVID-19 pandemic. The FFCR Act and the CARES Act contain numerous tax-related provisions relating to refundable payroll tax credits, deferment of employer side social security payments, net operating loss carryback periods, alternative minimum tax credit refunds, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property. The FFCR Act and CARES Act did not have a material impact on the Company’s unaudited condensed financial statements as of March 31, 2020; however, the Company continues to examine the impacts the FFCR Act and CARES Act may have on its business, results of operations, financial condition and liquidity.
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) under its accounting standard codifications (“ASC”) or other standard setting bodies and adopted by the Company as of the specified effective date, unless otherwise discussed below. Recently Adopted Accounting Pronouncements In August 2018, the FASB issued ASU No.2018-13 (Topic 820), Fair Value Measurement. ASU 2018-13 modifies the disclosure requirements on fair value measurement in Topic 820. For public entities, ASU 2018-13 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted. The Company adopted this ASU on January 1, 2020. The adoption of this standard did not have a material impact on the Company’s financial statements. New Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) Codification Improvements to Topic 842, Leases and ASU No. 2018-11, Leases (Topic 842): Targeted Improvements Leases (Topic 842) Codification Improvements In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326)

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2020
Fair Value Disclosures [Abstract]
Schedule of Financial Assets Measured and Recognized at Fair Value	As of March 31, 2020, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at March 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 U.S. government bonds $ 10,043 $ — $ — $ 10,043 Corporate bonds — 50,104 — 50,104 Asset backed securities — 21,084 — 21,084 Marketable Securities 10,043 71,188 — 81,231 Money market funds (1) 22,879 — — 22,879 Total fair value of assets $ 32,922 $ 71,188 $ — $ 104,110 (1) Included in cash and cash equivalents on the balance sheet. Fair Value Measurements at March 31, 2020 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimate Fair Value Assets U.S. government bonds $ 10,043 $ 83 $ — $ 10,126 Corporate bonds 50,104 — (64 ) 50,040 Asset backed securities 21,084 2 (36 ) 21,050 Marketable securities 81,231 85 (100 ) 81,216 Money market funds (1) 22,879 — — 22,879 Total fair value of assets $ 104,110 $ 85 $ (100 ) $ 104,095 (1) Included in cash and cash equivalents on the balance sheet. As of December 31, 2019, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at December 31, 2019 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 $ 10,062 $ — $ — $ 10,062 Overnight repurchase agreements (1) 14,000 — — 14,000 Corporate bonds — 64,285 — 64,285 Asset backed securities — 20,781 — 20,781 Marketable securities 24,062 85,066 — 109,128 Money market funds (1) 8,730 — — 8,730 Total fair value of assets $ 32,792 $ 85,066 $ — $ 117,858 (1) Included in cash and cash equivalents on the balance sheet. Fair Value Measurements at December 31, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimate Fair Value Assets U.S. government bonds $ 10,062 $ 1 $ — $ 10,063 Overnight repurchase agreements (1) 14,000 — — 14,000 Corporate bonds 64,285 17 (7 ) 64,295 Asset backed securities 20,781 7 (1 ) 20,787 Marketable securities 109,128 25 (8 ) 109,145 Money market funds (1) 8,730 — — 8,730 Total fair value of assets $ 117,858 $ 25 $ (8 ) $ 117,875 (1) Included in cash and cash equivalents on the balance sheet.

Accrued and Other Current Lia_2

Accrued and Other Current Liabilities (Tables)	3 Months Ended
	Mar. 31, 2020
Payables And Accruals [Abstract]
Schedule of Accrued and Other Current Liabilities	Accrued and other current liabilities consisted of the following (in thousands): March 31, December 31, 2020 2019 Accrued salaries and benefits $ 555 $ 1,145 Accrued research and development expenses 827 88 Accrued professional services 327 248 Accrued interest 24 27 Other 80 202 Total $ 1,813 $ 1,710

Long-Term Debt (Tables)

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2020
Debt Disclosure [Abstract]
Summary of Future Contractual Maturities of Debt	As of March 31, 2020, the future contractual maturities of debt by fiscal year are as follows (in thousands): 2020 (remaining nine months) $ 1,500 2021 2,000 2022 833 Total future maturities of debt $ 4,333

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Activity Under 2019 Plan 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 (574,700 ) 574,700 $ 28.71 9.93 Options exercised — (4,200 ) $ 2.64 Balance, March 31, 2020 1,898,625 2,139,374 $ 10.31 8.96 Exercisable as of March 31, 2020 566,730 Vested and expected to vest, March 31, 2020 2,139,374
Summary of Stock Based Compensation Expense	Total stock-based compensation expense recorded related to options granted to employees and non-employees was as follows (in thousands): Three Months Ended March 31, 2020 2019 Research and development $ 185 $ 21 General and administrative 264 33 $ 449 $ 54

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2020
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): Three Months Ended March 31, 2020 2019 Numerator: Net loss attributable to common stockholders $ (11,773 ) $ (2,815 ) Denominator: Weighted-average shares outstanding 17,383,016 1,151,145 Less: weighted-average unvested restricted shares and shares subject to repurchase — (27,926 ) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 17,383,016 1,123,219 Net loss per share attributable to common stockholders, basic and diluted $ (0.68 ) $ (2.51 )
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: Three Months Ended March 31, 2020 2019 Options to purchase common stock 2,139,374 886,690 Unvested restricted common stock awards — 23,936 Warrants to purchase common stock 5,116 10,232 Convertible preferred stock — 3,046,355 Total 2,144,490 3,967,213

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2020
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 March 31, 2020 were as follows (in thousands): Operating Leases 2020 (remaining nine months) $ 225 2021 195 2022 83 Total minimum lease payments $ 503

Organization and Summary of S_3

Organization and Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 17, 2019	Oct. 31, 2019	Mar. 31, 2020	Dec. 31, 2019	Sep. 12, 2019
Organization And Summary Of Significant Accounting Policies [Line Items]
Aggregate gross proceeds from initial public offering	$ 82,500
Common stock, shares authorized			300,000,000	300,000,000
Common stock, par value (in dollars per share)			$ 0.0001	$ 0.0001
Common stock, shares issued			17,386,247	17,382,047
Accumulated deficit			$ 54,774	$ 43,001
Cash, cash equivalents and short-term investments			104,100
Accumulated depreciation			$ 200	$ 200
Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets			5 years
Minimum [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of assets			3 years
IPO | Common Stock
Organization And Summary Of Significant Accounting Policies [Line Items]
Share issued	5,500,000
Shares issued, price per share	$ 15
Shares issued upon conversion	9,936,341
Common stock, shares authorized					300,000,000
Common stock, par value (in dollars per share)					$ 0.0001
IPO | Preferred Stock
Organization And Summary Of Significant Accounting Policies [Line Items]
Preferred stock, shares authorized					10,000,000
Preferred stock per value					$ 0.0001
Over-Allotment Option
Organization And Summary Of Significant Accounting Policies [Line Items]
Shares issued, price per share		$ 15
Common stock, shares issued		552,116
Gross proceeds from issuance of common stock		$ 8,300
Over-Allotment Option | Maximum
Organization And Summary Of Significant Accounting Policies [Line Items]
Additional share issued period	825,000

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets Measured and Recognized at Fair Value (Details) - Recurring - USD ($) $ in Thousands		Mar. 31, 2020	Dec. 31, 2019
Assets
Marketable Securities		$ 81,231	$ 109,128
Total fair value of assets		104,110	117,858
Marketable Securities Amortized Cost		81,231	109,128
Marketable Securities Gross Unrealized Gains		85	25
Marketable Securities Gross Unrealized Losses		(100)	(8)
Marketable Securities Estimate Fair Value		81,216	109,145
Amortized Cost		104,110	117,858
Gross Unrealized Gains		85	25
Gross Unrealized Losses		(100)	(8)
Estimate Fair Value		104,095	117,875
U.S. Government Bonds
Assets
Marketable Securities		10,043	10,062
Marketable Securities Amortized Cost		10,043	10,062
Marketable Securities Gross Unrealized Gains		83	1
Marketable Securities Estimate Fair Value		10,126	10,063
Overnight Repurchase Agreements
Assets
Marketable Securities	[1]		14,000
Marketable Securities Amortized Cost	[1]		14,000
Marketable Securities Estimate Fair Value	[1]		14,000
Corporate Bonds
Assets
Marketable Securities		50,104	64,285
Marketable Securities Amortized Cost		50,104	64,285
Marketable Securities Gross Unrealized Gains			17
Marketable Securities Gross Unrealized Losses		(64)	(7)
Marketable Securities Estimate Fair Value		50,040	64,295
Asset Backed Securities
Assets
Marketable Securities		21,084	20,781
Marketable Securities Amortized Cost		21,084	20,781
Marketable Securities Gross Unrealized Gains		2	7
Marketable Securities Gross Unrealized Losses		(36)	(1)
Marketable Securities Estimate Fair Value		21,050	20,787
Money Market Funds
Assets
Money market funds	[1]	22,879	8,730
Amortized Cost	[1]	22,879	8,730
Estimate Fair Value	[1]	22,879	8,730
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Marketable Securities		10,043	24,062
Total fair value of assets		32,922	32,792
Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Government Bonds
Assets
Marketable Securities		10,043	10,062
Quoted Prices in Active Markets for Identical Assets (Level 1) | Overnight Repurchase Agreements
Assets
Marketable Securities	[1]		14,000
Quoted Prices in Active Markets for Identical Assets (Level 1) | Money Market Funds
Assets
Money market funds	[1]	22,879	8,730
Significant Other Observable Inputs (Level 2)
Assets
Marketable Securities		71,188	85,066
Total fair value of assets		71,188	85,066
Significant Other Observable Inputs (Level 2) | Corporate Bonds
Assets
Marketable Securities		50,104	64,285
Significant Other Observable Inputs (Level 2) | Asset Backed Securities
Assets
Marketable Securities		$ 21,084	$ 20,781
[1]	Included in cash and cash equivalents on the balance sheet.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of financial liabilities measured and recognized	$ 0	$ 0

Accrued and Other Current Lia_3

Accrued and Other Current Liabilities - Schedule of Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued salaries and benefits	$ 555	$ 1,145
Accrued research and development expenses	827	88
Accrued professional services	327	248
Accrued interest	24	27
Other	80	202
Total	$ 1,813	$ 1,710

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended
	Apr. 30, 2019	Mar. 31, 2020	Dec. 31, 2019	Sep. 17, 2019
IPO | Common Stock
Class Of Stock [Line Items]
Shares issued price per share				$ 15
Redeemable convertible preferred stock converted into share of common stock		9,936,341
Redeemable convertible preferred stock outstanding, shares		0	0
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Preferred stock, shares issued	6,889,986
Gross proceeds from issuance of convertible preferred stock	$ 61.7
Shares issued price per share	$ 8.95444

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) - USD ($)	Oct. 26, 2018	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Long-term debt net of debt discount and issuance costs		$ 4,333,000
Loan Agreement | Silicon Valley Bank
Debt Instrument [Line Items]
Debt instrument, maximum borrowing capacity	$ 10,000,000
Debt instrument, increments amount	$ 1,000,000
Debt instrument, floating interest rate percentage	6.50%
Debt instrument, interest rate increase percentage	5.00%
Debt instrument, maturity date	May 1, 2022
Long-term debt net of debt discount and issuance costs		4,500,000
Accrued liabilities related to accretion of final payment included in long-term debt		$ 200,000	$ 100,000
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
Loan Agreement | Silicon Valley Bank | Term Loans
Debt Instrument [Line Items]
Debt instrument, remaining borrowing capacity	$ 5,000,000

Long-Term Debt - Summary of Fut

Long-Term Debt - Summary of Future Contractual Maturities of Debt (Details) $ in Thousands	Mar. 31, 2020USD ($)
Debt Disclosure [Abstract]
2020 (remaining nine months)	$ 1,500
2021	2,000
2022	833
Total future maturities of debt	$ 4,333

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended
	Jan. 31, 2020	Mar. 31, 2020	Mar. 31, 2019	Sep. 30, 2019
Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding Options, Number of Shares, Options granted		574,700	110,637
Non-employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding Options, Number of Shares, Options granted		574,700	110,637
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
Weighted average grant-date fair value of options granted		$ 17.04	$ 3.20
Unrecognized stock-based compensation expense		$ 12.4
Unrecognized stock-based compensation expense, weighted-average recognition period		3 years 1 month 6 days
Fair value of options vested		$ 0.3
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 [Member]
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 [Member] | 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]
Fair value of options vested			$ 0.1
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
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in number of common stock shares available for Issuance	695,281
2019 Employee Share Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares reserved for issuance		333,820		160,000

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Activity Under 2019 Plan and 2016 Plan (Details) - 2019 and 2016 Incentive Award Plan - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Available for Grant, Beginning Balance	1,778,044
Shares Available for Grant, Additional shares authorized	695,281
Shares Available for Grant, Options granted	(574,700)
Shares Available for Grant, Ending Balance	1,898,625	1,778,044
Shares Available for Grant, Exercisable as of March 31, 2020	566,730
Shares Available for Grant, Vested and expected to vest, March 31, 2020	2,139,374
Outstanding Options, Number of Shares, Beginning Balance	1,568,874
Outstanding Options, Number of Shares, Options granted	574,700
Outstanding Options, Number of Shares, Options exercised	(4,200)
Outstanding Options, Number of Shares, Ending Balance	2,139,374	1,568,874
Outstanding Options, Weighted Average Exercise Price, Beginning Balance	$ 3.55
Outstanding Options, Weighted Average Exercise Price, Options granted	28.71
Outstanding Options, Weighted Average Exercise Price, Options exercised	2.64
Outstanding Options, Weighted Average Exercise Price, Ending Balance	$ 10.31	$ 3.55
Weighted Average Remaining Contractual Term, Balance	8 years 11 months 15 days	8 years 10 months 6 days
Weighted Average Remaining Contractual Term, Options granted	9 years 11 months 4 days

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 449	$ 54
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	185	21
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 264	$ 33

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	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net loss attributable to common stockholders	$ (11,773)	$ (2,815)
Denominator:
Weighted-average shares outstanding	17,383,016	1,151,145
Less: weighted-average unvested restricted shares and shares subject to repurchase		(27,926)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	17,383,016	1,123,219
Net loss per share attributable to common stockholders, basic and diluted	$ (0.68)	$ (2.51)

Net Loss per Share - Schedule o

Net Loss per Share - Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding	2,144,490	3,967,213
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding		3,046,355
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding	2,139,374	886,690
Unvested Restricted Common Stock Awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding		23,936
Warrants to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding	5,116	10,232

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) $ in Millions	Sep. 12, 2019USD ($)Owedshares	Apr. 30, 2019USD ($)shares	Feb. 28, 2018shares	Mar. 31, 2020shares
SNBL | IPO
Related Party Transaction [Line Items]
Issuance of common stock, net of issuance costs, Shares				233,333
Series B Convertible Preferred Stock | SNBL
Related Party Transaction [Line Items]
Issuance of common stock, net of issuance costs, Shares		307,110
Issuance of common stock, net of issuance costs | $		$ 2.7
Series A convertible preferred stock | SNBL | Convertible Note
Related Party Transaction [Line Items]
Debt instrument converted, shares issued			33,741
Series A And Series B Convertible Preferred Stock | IPO
Related Party Transaction [Line Items]
Issuance of common stock, net of issuance costs, Shares	2,633,333
Issuance of common stock, net of issuance costs | $	$ 39.5
Debt instrument converted, shares issued	3,887,668
Number of owed shareholders | Owed	2
Percentage of minimum convertible preferred stock owning of equity on converted basis	10.00%
Shares issued upon conversion	3,887,668

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Non-cancelable Operating Leases (Details) $ in Thousands	Mar. 31, 2020USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2020 (remaining nine months)	$ 225
2021	195
2022	83
Total minimum lease payments	$ 503

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income tax provision	$ 0	$ 0