Satsuma Pharmaceuticals (STSA) 10-Q 12 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 08, 2019
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Registrant Name	Satsuma Pharmaceuticals, Inc.
Entity Central Index Key	0001692830
Entity Current Reporting Status	No
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	false
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		17,375,664

Condensed Balance Sheets (Unaud

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 77,664	$ 5,205
Short-term marketable securities	41,284
Prepaid expenses and other current assets	7,635	199
Total current assets	126,583	5,404
Property and equipment, net	885	445
Other non-current assets	76	532
Total assets	127,544	6,381
Liabilities
Accounts payable	2,601	327
Accrued and other current liabilities	1,694	1,497
Current portion of long-term debt	1,643	141
Total current liabilities	5,938	1,965
Long-term debt	3,419	4,824
Other noncurrent liabilities	66	76
Total liabilities	9,423	6,865
Commitments and Contingencies (Note 9)
Series A convertible preferred stock, $0.0001 par value, 10,000,000 shares authorized as of September 30, 2019 and 3,191,489 shares authorized as of December 31, 2018; no shares issued and outstanding as of September 30, 2019 and 3,046,355 shares issued and outstanding as of December 31, 2018; liquidation value of $0 as of September 30, 2019 and $12,134 as of December 31, 2018		11,648
Stockholders’ equity (deficit)
Common stock, $0.0001 par value, 300,000,000 shares and 5,319,148 shares authorized as of September 30, 2019 and December 31, 2018, respectively; 16,815,569 shares and 1,083,280 shares issued and outstanding as of September 30, 2019 and December 31, 2018	3	1
Additional paid-in-capital	150,298	2,693
Accumulated other comprehensive income	12
Accumulated deficit	(32,192)	(14,826)
Total stockholders’ equity (deficit)	118,121	(12,132)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 127,544	6,381
Series A Preferred Stock
Liabilities
Series A convertible preferred stock, $0.0001 par value, 10,000,000 shares authorized as of September 30, 2019 and 3,191,489 shares authorized as of December 31, 2018; no shares issued and outstanding as of September 30, 2019 and 3,046,355 shares issued and outstanding as of December 31, 2018; liquidation value of $0 as of September 30, 2019 and $12,134 as of December 31, 2018		$ 11,648

Condensed Balance Sheets (Una_2

Condensed Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Convertible preferred stock, authorized	10,000,000	3,191,489
Convertible preferred stock, issued	0	3,046,355
Convertible preferred stock, outstanding	0	3,046,355
Convertible preferred stock, liquidation value	$ 0	$ 12,134
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	5,319,148
Common stock, shares issued	16,815,569	1,083,280
Common stock, shares outstanding	16,815,569	1,083,280

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Operating expenses
Research and development	$ 7,441	$ 1,380	$ 15,046	$ 4,479
General and administrative	1,029	220	2,560	752
Total operating expenses	8,470	1,600	17,606	5,231
Loss from operations	(8,470)	(1,600)	(17,606)	(5,231)
Interest income	331	13	602	46
Interest expense	(121)		(365)	(2)
Other income, net			3	185
Net loss	(8,260)	(1,587)	(17,366)	(5,002)
Unrealized gains on marketable securities	12
Comprehensive loss	$ (8,248)	$ (1,587)	$ (17,366)	$ (5,002)
Net loss per share attributable to common stockholders, basic and diluted	$ (2.26)	$ (1.48)	$ (8.74)	$ (4.96)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	3,658,504	1,071,313	1,986,190	1,009,242

Condensed Statements of Convert

Condensed Statements of Convertible Preferred Stock and Stockholders Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Convertible Preferred Stock	Series B Convertible Preferred Stock	Redeemable Convertible Preferred Stock	Series A Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	AOCI Attributable to Parent
Beginning balance at Dec. 31, 2017	$ (5,432)						$ 2,048	$ (7,480)
Temporary equity, Beginning balance, Shares at Dec. 31, 2017		1,506,307
Temporary equity, Beginning balance at Dec. 31, 2017		$ 5,528
Beginning balance, Shares at Dec. 31, 2017						574,468
Vesting of restricted stock, Shares						15,956
Stock-based compensation	107						107
Net loss	(3,415)							(3,415)
Issuance of common stock on settlement of obligation to issue additional common stock	472					$ 1	471
Issuance of common stock on settlement of obligation to issue additional common stock, Shares						476,897
Issuance of convertible preferred stock for cash, net of issuance costs, Shares					1,506,307
Issuance of convertible preferred stock for cash, net of issuance costs					$ 5,986
Conversion of convertible note into Series A convertible preferred stock, including interest of $8 adjusted for derivative liability of $27		33,741
Conversion of convertible note into Series A convertible preferred stock, Shares		$ 134
Ending balance at Jun. 30, 2018	(8,268)					$ 1	2,626	(10,895)
Temporary equity, Ending balance, Shares at Jun. 30, 2018		3,046,355
Temporary equity, Ending balance at Jun. 30, 2018		$ 11,648
Ending Balance, Shares at Jun. 30, 2018						1,067,321
Beginning balance at Dec. 31, 2017	(5,432)						2,048	(7,480)
Temporary equity, Beginning balance, Shares at Dec. 31, 2017		1,506,307
Temporary equity, Beginning balance at Dec. 31, 2017		$ 5,528
Beginning balance, Shares at Dec. 31, 2017						574,468
Net loss	(5,002)
Ending balance at Sep. 30, 2018	(9,824)					$ 1	2,657	(12,482)
Temporary equity, Ending balance, Shares at Sep. 30, 2018		3,046,355
Temporary equity, Ending balance at Sep. 30, 2018		$ 11,648
Ending Balance, Shares at Sep. 30, 2018						1,075,299
Beginning balance at Jun. 30, 2018	(8,268)					$ 1	2,626	(10,895)
Temporary equity, Beginning balance, Shares at Jun. 30, 2018		3,046,355
Temporary equity, Beginning balance at Jun. 30, 2018		$ 11,648
Beginning balance, Shares at Jun. 30, 2018						1,067,321
Vesting of restricted stock, Shares						7,978
Stock-based compensation	31						31
Net loss	(1,587)							(1,587)
Ending balance at Sep. 30, 2018	(9,824)					$ 1	2,657	(12,482)
Temporary equity, Ending balance, Shares at Sep. 30, 2018		3,046,355
Temporary equity, Ending balance at Sep. 30, 2018		$ 11,648
Ending Balance, Shares at Sep. 30, 2018						1,075,299
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	3,046,355			3,046,355
Temporary equity, Beginning balance at Dec. 31, 2018	$ 11,648	$ 11,648			$ 11,648
Beginning balance, Shares at Dec. 31, 2018						1,083,280
Vesting of restricted stock, Shares						15,956
Stock-based compensation	198						198
Net loss	(9,106)							(9,106)
Issuance of common stock upon exercise of stock options	53						53
Issuance of common stock upon exercise of stock options, Shares						53,721
Issuance of convertible preferred stock for cash, net of issuance costs, Shares			6,889,986
Issuance of convertible preferred stock for cash, net of issuance costs			$ 61,490
Ending balance at Jun. 30, 2019	(20,987)					$ 1	2,944	(23,932)
Temporary equity, Ending balance, Shares at Jun. 30, 2019		9,936,341
Temporary equity, Ending balance at Jun. 30, 2019		$ 73,138
Ending Balance, Shares at Jun. 30, 2019						1,152,957
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	3,046,355			3,046,355
Temporary equity, Beginning balance at Dec. 31, 2018	$ 11,648	$ 11,648			$ 11,648
Beginning balance, Shares at Dec. 31, 2018						1,083,280
Conversion of redeemable convertible preferred stock into common stock, Shares			9,936,341
Net loss	$ (17,366)
Issuance of common stock upon exercise of stock options, Shares	267,212
Ending balance at Sep. 30, 2019	$ 118,121					$ 3	150,298	(32,192)	$ 12
Temporary equity, Ending balance, Shares at Sep. 30, 2019	0
Ending Balance, Shares at Sep. 30, 2019						16,815,569
Beginning balance at Jun. 30, 2019	$ (20,987)					$ 1	2,944	(23,932)
Temporary equity, Beginning balance, Shares at Jun. 30, 2019		9,936,341
Temporary equity, Beginning balance at Jun. 30, 2019		$ 73,138
Beginning balance, Shares at Jun. 30, 2019						1,152,957
Conversion of redeemable convertible preferred stock into common stock	73,138					$ 1	73,137
Temporary Equity, Conversion of redeemable convertible preferred stock into common stock, Shares				(9,936,341)
Temporary Equity, Conversion of redeemable convertible preferred stock into common stock				$ (73,138)
Conversion of redeemable convertible preferred stock into common stock, Shares						9,936,341
Issuance of common stock upon initial public offering, net of issuance costs of $8,752	73,748					$ 1	73,747
Issuance of common stock upon initial public offering, net of issuance costs, Shares						5,500,000
Vesting of restricted stock, Shares						7,979
Stock-based compensation	224						224
Net loss	(8,260)							(8,260)
Issuance of common stock upon exercise of stock options	246						246
Issuance of common stock upon exercise of stock options, Shares						213,491
Other comprehensive income	12								12
Issuance of common stock upon net exercise of common stock warrants, Shares						4,801
Ending balance at Sep. 30, 2019	$ 118,121					$ 3	$ 150,298	$ (32,192)	$ 12
Temporary equity, Ending balance, Shares at Sep. 30, 2019	0
Ending Balance, Shares at Sep. 30, 2019						16,815,569

Condensed Statements of Conve_2

Condensed Statements of Convertible Preferred Stock and Stockholders Equity (Deficit) (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Jun. 30, 2018
Common stock issuance costs	$ 8,752
Series B Convertible Preferred Stock
Issuance of stock, net of issuance costs		$ 206
Series A Convertible Preferred Stock
Issuance of stock, net of issuance costs			$ 14
Conversion of convertible note interest			8
Conversion of convertible note derivative liability			$ 27

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities
Net loss	$ (17,366)	$ (5,002)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and amortization	102	31
Non-cash interest expense, and amortization of debt discount and issuance costs	98
Net amortization of premiums and discounts on marketable securities	49	2
Stock-based compensation	422	138
Change in fair value of derivative liability		1
Change in fair value of obligation to issue additional common stock		101
Change in fair value of convertible preferred stock tranche liability		(291)
Loss on extinguishment of convertible note		4
Changes in assets and liabilities
Prepaid expenses and other assets	(6,980)	62
Accounts payable	1,387	(349)
Accrued and other current liabilities	(152)	28
Other non-current liabilities	(10)	18
Net cash used in operating activities	(22,450)	(5,257)
Cash flows from investing activities
Purchases of marketable securities	(41,321)
Purchases of property and equipment	(463)	(201)
Net cash used in investing activities	(41,784)	(201)
Cash flows from financing activities
Proceeds from issuance of convertible preferred stock, net of issuance costs	61,490	5,986
Proceeds from issuance of initial public offering	74,904
Proceeds from exercise of common stock options	299
Net cash provided by financing activities	136,693	5,986
Net increase in cash and cash equivalents	72,459	528
Cash and cash equivalents
Cash and cash equivalents, at beginning of period	5,205	1,658
Cash and cash equivalents, at end of period	77,664	2,186
Supplemental disclosure of cash flow information:
Cash paid for income taxes	9	4
Cash paid for interest	265
Supplemental non-cash investing and financing activities:
Unpaid deferred offering costs included in accounts payable and accrued and other current liabilities	1,156
Purchases of property and equipment in accounts payable and accrued and other current liabilities	108	144
Issuance of common stock warrants in connection with long-term debt		4
Conversion of redeemable convertible preferred stock into common stock	$ 73,138
Conversion of convertible note and accrued interest into preferred stock		134
Issuance of common stock to settle liability for obligation to issue additional common stock		$ 471

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
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 (see Note 11). 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. 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 $32.2 million as of September 30, 2019. The Company has historically financed its operations primarily through private placements of convertible preferred stock, a convertible promissory note, and long-term debt. 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 September 30, 2019, the Company had cash and cash equivalents and short-term marketable securities of $118.9 million. The Company’s management believes that the Company’s current cash and cash equivalents 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. 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 September 30, 2019, the statements of operations and comprehensive loss, the statements of convertible preferred stock and stockholders’ equity (deficit) for the three and nine months ended September 30, 2019 and 2018 and statements of cash flows for the nine months ended September 30, 2019 and 2018 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 September 30, 2019 and the results of its operations and its cash flows for the nine months ended September 30, 2019 and 2018. The financial data and other information disclosed in these notes related to the nine months ended September 30, 2019 and 2018 are also unaudited. The results for the nine months ended September 30, 2019 are not necessarily indicative of results to be expected for the year ending December 31, 2019, any other interim periods, or any future year or period. The balance sheet as of December 31, 2018 included herein was derived from the audited financial statements as of that date. Certain disclosures have been condensed or omitted from the 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, 2018, which are included in the Company’s prospectus related to the Company’s IPO, dated September 12, 2019, pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended (the “Securities Act”). Reverse Stock Split On September 11, 2019, the Company effected a 1-for-4.7 reverse stock split of the Company’s common stock and convertible preferred stock. All issued and outstanding common stock, convertible preferred stock, stock options and per share amounts contained in the accompanying unaudited unaudited 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 expenses during the reporting period. Such estimates include the accrual of research and development expenses, common stock valuation and related stock-based compensation. 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. 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 and cash equivalents. 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 money market funds and overnight repurchase agreements. The Company has not experienced any material 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 short-term marketable securities. Deferred Offering Costs The Company capitalizes costs that are directly associated with in-process equity financings, including the initial public offering, 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. 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 notes, 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 is 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. 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. 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 Leases (Topic 842): Targeted Improvements

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
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 September 30, 2019, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at September 30, 2019 Quoted Price in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Overnight Repurchase Agreements (1) $ 40,000 $ — $ — $ 40,000 Corporate Bonds — 16,695 — 16,695 Asset Backed Securities — 24,578 — 24,578 Marketable Securities 40,000 41,273 — 81,273 Money market funds (1) 37,638 — — 37,638 Total fair value of assets $ 77,638 $ 41,273 $ — $ 118,911 Fair Value Measurements at September 30, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimate Fair Value Assets Overnight Repurchase Agreements (1) $ 40,000 $ — $ — $ 40,000 Corporate Bonds 16,695 14 (5 ) 16,704 Asset Backed Securities 24,578 3 — 24,581 Marketable securities 81,273 17 (5 ) 81,285 Money market funds (1) 37,638 — — 37,638 Total fair value of assets $ 118,911 $ 17 $ (5 ) $ 118,923 (1) Included in cash and cash equivalents on the balance sheet. As of December 31, 2018, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at December 31, 2018 Quoted Price in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Money market funds (1) $ 5,184 $ — $ — $ 5,184 Total fair value of assets $ 5,184 $ — $ — $ 5,184 (1) Included in cash and cash equivalents on the balance sheet. There were no financial liabilities measured and recognized at fair value as of September 30, 2019 and December 31, 2018.

Accrued and Other Current Liabi

Accrued and Other Current Liabilities	9 Months Ended
	Sep. 30, 2019
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): September 30, December 31, 2019 2018 Accrued salaries and benefits $ 674 $ 553 Deferred offering costs 348 — Accrued research and development expenses 341 772 Accrued interest 27 29 Other 304 143 Total $ 1,694 $ 1,497

Convertible Preferred Stock

Convertible Preferred Stock	9 Months Ended
	Sep. 30, 2019
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. Issued and outstanding redeemable convertible preferred stock and its principal terms as of December 31, 2018 were as follows (in thousands, except share and per share amounts): Redeemable Convertible Preferred Stock Liquidation Value Carrying Amount Original Issue Price Authorized Outstanding Series A convertible preferred stock 3,191,489 3,046,355 $ 12,134 $ 11,648 $ 3.9833 3,191,489 3,046,355 $ 12,134 $ 11,648 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 September 30, 2019.

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2019
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 September 30, 2019, the future contractual maturities of debt by fiscal year are as follows (in thousands): 2019 remaining three months $ 167 2020 2,000 2021 2,000 2022 833 Total future maturities of debt $ 5,000 As of September 30, 2019, the term loan advances, net of debt discount and debt issuance costs, were $5.1 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 $0.1 million and less than $0.1 million as of September 30, 2019 and December 31, 2018, respectively, included in long-term debt on the Company’s condensed balance sheet.

Stock-Based Compensation

Stock-Based Compensation	9 Months Ended
	Sep. 30, 2019
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 ISOs, NSOs, SARs or 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. Activity under the equity incentive plans 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, 2019 114,905 829,775 $ 0.97 8.82 Additional shares authorized 2,675,831 — Options granted (1,022,118 ) 1,022,118 $ 3.50 9.63 Options exercised — (267,212 ) $ 1.12 Options cancelled 15,426 (15,424 ) $ 1.03 Balance, September 30, 2019 1,784,044 1,569,257 $ 3.50 9.09 Exercisable as of September 30, 2019 341,097 Vested and expected to vest, September 30, 2019 1,569,257 The weighted-average grant-date fair value of options granted during the nine months ended September 30, 2019 and 2018 was $3.41 and $0.67 per share, respectively. During the nine months ended September 30, 2019, there were 267,212 stock options exercised under the 2016 Plan. As of September 30, 2019, the total unrecognized stock-based compensation expense for stock options was $3.3 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 nine months ended September 30, 2019 and 2018 was $0.4 million and $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 nine months ended September 30, 2019 and 2018, the Company granted stock options to employees to purchase 1,017,111 and 402,121 shares of common stock, respectively. During the nine months ended September 30, 2019 and 2018, the Company granted stock options to non-employees to purchase 5,106 and 0 shares of common stock, respectively. Fair Value of Common Stock Prior to the Company’s 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 determines 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 September 30, 2019, no offerings have been authorized to date. 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 September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Research and development $ 106 $ 15 $ 193 $ 84 General and administrative 118 16 229 54 $ 224 $ 31 $ 422 $ 138

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	9 Months Ended
	Sep. 30, 2019
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 September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Numerator: Net loss attributable to common stockholders $ (8,260 ) $ (1,587 ) $ (17,366 ) $ (5,002 ) Denominator: Weighted-average shares outstanding 3,670,472 1,115,196 2,006,074 1,061,041 Less: weighted-average unvested restricted shares and shares subject to repurchase (11,968 ) (43,883 ) (19,884 ) (51,799 ) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 3,658,504 1,071,313 1,986,190 1,009,242 Net loss per share attributable to common stockholders, basic and diluted $ (2.26 ) $ (1.48 ) $ (8.74 ) $ (4.96 ) 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: Nine Months Ended September 30, 2019 2018 Options to purchase common stock 1,569,257 829,775 Unvested restricted common stock awards 7,979 39,894 Warrants to purchase common stock 5,116 — Convertible preferred stock — 3,046,355 Total 1,582,352 3,916,024

Related Party Transaction

Related Party Transaction	9 Months Ended
	Sep. 30, 2019
Related Party Transactions [Abstract]
Related Party Transactions	8. Related Party Transactions In August 2016, the Company signed the Convertible Note with SNBL for $0.1 million, which was later amended in December 2016. In February 2018, the Convertible Note and related accrued interest of less than $0.1 million converted into 33,741 shares of Company’s Series A convertible preferred stock. In December 2016, as part of the Series A convertible preferred stock financing, the Company granted to SNBL a right to obtain shares of common stock for no additional paid-in capital (the “SNBL Grant”) upon the occurrence of subsequent closings of the Company’s Series A convertible preferred stock financing such that SNBL’s percentage ownership of the fully-diluted capitalization of the Company following the SNBL Grant would be equal to 20% following the final closing of the Series A convertible preferred stock financing. In February 2018, the Company issued 476,897 shares of common stock to SNBL for no consideration. Upon extinguishment of the obligation to issue additional common stock to SNBL, the obligation to issue additional common stock to SNBL was remeasured to its estimated fair value of $0.5 million and $0.1 million was recorded as a loss in other income, net for the nine months ended September 30, 2018, and the estimated fair value of $0.5 million of the obligation to issue additional common stock to SNBL was reclassified to additional paid-in capital on the balance sheet. 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 as discussed in Note 4. Besides converting their outstanding Series A and Series B preferred stock into the common stock as discussed in Note 4, two principal owners purchased 6,521,001 shares of the Company’s common stock upon the close of the IPO in September 2019.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
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 September 30, 2019 were as follows (in thousands): Operating Leases 2019 remaining three months $ 73 2020 299 2021 195 2022 83 Total minimum lease payments $ 650

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	10. Income Taxes For the nine months ended September 30, 2019 and 2018, 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	9 Months Ended
	Sep. 30, 2019
Subsequent Events [Abstract]
Subsequent Events	11. Subsequent Events In October 2019, the Company sold and issued an additional 552,116 shares of common stock at $15.00 per share to the underwriters of the IPO following the partial exercise of their option to purchase additional shares for gross proceeds of $8.3 million before underwriter commissions and other offering costs For the purposes of the interim financial statements as of September 30, 2019 and for the nine months ended, the Company has evaluated the subsequent events through November 12, 2019, the date the unaudited interim condensed financial statements were issued.

Organization and Summary of S_2

Organization and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
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 (see Note 11). 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. 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 $32.2 million as of September 30, 2019. The Company has historically financed its operations primarily through private placements of convertible preferred stock, a convertible promissory note, and long-term debt. 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 September 30, 2019, the Company had cash and cash equivalents and short-term marketable securities of $118.9 million. The Company’s management believes that the Company’s current cash and cash equivalents 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.
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 September 30, 2019, the statements of operations and comprehensive loss, the statements of convertible preferred stock and stockholders’ equity (deficit) for the three and nine months ended September 30, 2019 and 2018 and statements of cash flows for the nine months ended September 30, 2019 and 2018 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 September 30, 2019 and the results of its operations and its cash flows for the nine months ended September 30, 2019 and 2018. The financial data and other information disclosed in these notes related to the nine months ended September 30, 2019 and 2018 are also unaudited. The results for the nine months ended September 30, 2019 are not necessarily indicative of results to be expected for the year ending December 31, 2019, any other interim periods, or any future year or period. The balance sheet as of December 31, 2018 included herein was derived from the audited financial statements as of that date. Certain disclosures have been condensed or omitted from the 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, 2018, which are included in the Company’s prospectus related to the Company’s IPO, dated September 12, 2019, pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended (the “Securities Act”).
Reverse Stock Split	Reverse Stock Split On September 11, 2019, the Company effected a 1-for-4.7 reverse stock split of the Company’s common stock and convertible preferred stock. All issued and outstanding common stock, convertible preferred stock, stock options and per share amounts contained in the accompanying unaudited unaudited
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 expenses during the reporting period. Such estimates include the accrual of research and development expenses, common stock valuation and related stock-based compensation. 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. 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 and cash equivalents. 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 money market funds and overnight repurchase agreements. The Company has not experienced any material 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 short-term marketable securities.
Deferred Offering Costs	Deferred Offering Costs The Company capitalizes costs that are directly associated with in-process equity financings, including the initial public offering, 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.
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 notes, 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 is 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.
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. 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 Leases (Topic 842): Targeted Improvements

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Schedule of Financial Assets Measured and Recognized at Fair Value	As of September 30, 2019, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at September 30, 2019 Quoted Price in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Overnight Repurchase Agreements (1) $ 40,000 $ — $ — $ 40,000 Corporate Bonds — 16,695 — 16,695 Asset Backed Securities — 24,578 — 24,578 Marketable Securities 40,000 41,273 — 81,273 Money market funds (1) 37,638 — — 37,638 Total fair value of assets $ 77,638 $ 41,273 $ — $ 118,911 Fair Value Measurements at September 30, 2019 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimate Fair Value Assets Overnight Repurchase Agreements (1) $ 40,000 $ — $ — $ 40,000 Corporate Bonds 16,695 14 (5 ) 16,704 Asset Backed Securities 24,578 3 — 24,581 Marketable securities 81,273 17 (5 ) 81,285 Money market funds (1) 37,638 — — 37,638 Total fair value of assets $ 118,911 $ 17 $ (5 ) $ 118,923 (1) Included in cash and cash equivalents on the balance sheet. As of December 31, 2018, financial assets measured and recognized at fair value were as follows (in thousands): Fair Value Measurements at December 31, 2018 Quoted Price in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Total Assets Money market funds (1) $ 5,184 $ — $ — $ 5,184 Total fair value of assets $ 5,184 $ — $ — $ 5,184 (1) Included in cash and cash equivalents on the balance sheet.

Accrued and Other Current Lia_2

Accrued and Other Current Liabilities (Tables)	9 Months Ended
	Sep. 30, 2019
Payables And Accruals [Abstract]
Schedule of Accrued and Other Current Liabilities	Accrued and other current liabilities consisted of the following (in thousands): September 30, December 31, 2019 2018 Accrued salaries and benefits $ 674 $ 553 Deferred offering costs 348 — Accrued research and development expenses 341 772 Accrued interest 27 29 Other 304 143 Total $ 1,694 $ 1,497

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	9 Months Ended
	Sep. 30, 2019
Equity [Abstract]
Summary of Issued and Outstanding Redeemable Convertible Preferred Stock and Principal Terms	Issued and outstanding redeemable convertible preferred stock and its principal terms as of December 31, 2018 were as follows (in thousands, except share and per share amounts): Redeemable Convertible Preferred Stock Liquidation Value Carrying Amount Original Issue Price Authorized Outstanding Series A convertible preferred stock 3,191,489 3,046,355 $ 12,134 $ 11,648 $ 3.9833 3,191,489 3,046,355 $ 12,134 $ 11,648

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2019
Debt Disclosure [Abstract]
Summary of Future Contractual Maturities of Debt	As of September 30, 2019, the future contractual maturities of debt by fiscal year are as follows (in thousands): 2019 remaining three months $ 167 2020 2,000 2021 2,000 2022 833 Total future maturities of debt $ 5,000

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Activity Under Equity Incentive Plans	Activity under the equity incentive plans 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, 2019 114,905 829,775 $ 0.97 8.82 Additional shares authorized 2,675,831 — Options granted (1,022,118 ) 1,022,118 $ 3.50 9.63 Options exercised — (267,212 ) $ 1.12 Options cancelled 15,426 (15,424 ) $ 1.03 Balance, September 30, 2019 1,784,044 1,569,257 $ 3.50 9.09 Exercisable as of September 30, 2019 341,097 Vested and expected to vest, September 30, 2019 1,569,257
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 September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Research and development $ 106 $ 15 $ 193 $ 84 General and administrative 118 16 229 54 $ 224 $ 31 $ 422 $ 138

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	9 Months Ended
	Sep. 30, 2019
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 September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Numerator: Net loss attributable to common stockholders $ (8,260 ) $ (1,587 ) $ (17,366 ) $ (5,002 ) Denominator: Weighted-average shares outstanding 3,670,472 1,115,196 2,006,074 1,061,041 Less: weighted-average unvested restricted shares and shares subject to repurchase (11,968 ) (43,883 ) (19,884 ) (51,799 ) Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted 3,658,504 1,071,313 1,986,190 1,009,242 Net loss per share attributable to common stockholders, basic and diluted $ (2.26 ) $ (1.48 ) $ (8.74 ) $ (4.96 )
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: Nine Months Ended September 30, 2019 2018 Options to purchase common stock 1,569,257 829,775 Unvested restricted common stock awards 7,979 39,894 Warrants to purchase common stock 5,116 — Convertible preferred stock — 3,046,355 Total 1,582,352 3,916,024

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2019
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 September 30, 2019 were as follows (in thousands): Operating Leases 2019 remaining three months $ 73 2020 299 2021 195 2022 83 Total minimum lease payments $ 650

Organization and Summary of S_3

Organization and Summary of Significant Accounting Policies - Additional Information (Details) $ / shares in Units, $ in Thousands	Sep. 17, 2019USD ($)$ / sharesshares	Sep. 11, 2019	Sep. 30, 2019USD ($)$ / sharesshares	Sep. 30, 2019USD ($)$ / sharesshares	Sep. 12, 2019$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares
Organization And Summary Of Significant Accounting Policies [Line Items]
Aggregate gross proceeds from initial public offering | $	$ 82,500			$ 74,904
Common stock, shares authorized			300,000,000	300,000,000		5,319,148
Common stock, par value (in dollars per share) | $ / shares			$ 0.0001	$ 0.0001		$ 0.0001
Accumulated deficit | $			$ 32,192	$ 32,192		$ 14,826
Cash, cash equivalents and short-term investments | $			$ 118,900	$ 118,900
Reverse stock split, conversion ratio		0.21
Common Stock
Organization And Summary Of Significant Accounting Policies [Line Items]
Share issued			5,500,000
IPO
Organization And Summary Of Significant Accounting Policies [Line Items]
Share issued	6,521,001
IPO | Common Stock
Organization And Summary Of Significant Accounting Policies [Line Items]
Share issued	5,500,000
Shares issued, price per share | $ / shares	$ 15
Shares issued upon conversion	9,936,341
Common stock, shares authorized					300,000,000
Common stock, par value (in dollars per share) | $ / shares					$ 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 | $ / shares					$ 0.0001
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) - USD ($) $ in Thousands		Sep. 30, 2019	Dec. 31, 2018
Assets
Short-term marketable securities		$ 41,284
Recurring
Assets
Short-term marketable securities		81,273
Money market funds	[1]		$ 5,184
Total fair value of assets		118,911	5,184
Marketable Securities Amortized Cost		81,273
Marketable securities Gross Unrealized Gains		17
Marketable Securities Gross Unrealized Losses		(5)
Marketable Securities Estimate Fair Value		81,285
Amortized Cost		118,911
Gross Unrealized Gains		17
Gross Unrealized Losses		(5)
Estimate Fair Value		118,923
Recurring | Overnight Repurchase Agreements
Assets
Short-term marketable securities	[1]	40,000
Marketable Securities Amortized Cost	[1]	40,000
Marketable Securities Estimate Fair Value	[1]	40,000
Recurring | Corporate Bonds
Assets
Short-term marketable securities		16,695
Marketable Securities Amortized Cost		16,695
Marketable securities Gross Unrealized Gains		14
Marketable Securities Gross Unrealized Losses		(5)
Marketable Securities Estimate Fair Value		16,704
Recurring | Asset Backed Securities
Assets
Short-term marketable securities		24,578
Marketable Securities Amortized Cost		24,578
Marketable securities Gross Unrealized Gains		3
Marketable Securities Estimate Fair Value		24,581
Recurring | Money Market Funds
Assets
Money market funds	[1]	37,638
Amortized Cost	[1]	37,638
Estimate Fair Value	[1]	37,638
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets
Short-term marketable securities		40,000
Money market funds	[1]		5,184
Total fair value of assets		77,638	$ 5,184
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Overnight Repurchase Agreements
Assets
Short-term marketable securities	[1]	40,000
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money Market Funds
Assets
Money market funds	[1]	37,638
Recurring | Significant Other Observable Inputs (Level 2)
Assets
Short-term marketable securities		41,273
Total fair value of assets		41,273
Recurring | Significant Other Observable Inputs (Level 2) | Corporate Bonds
Assets
Short-term marketable securities		16,695
Recurring | Significant Other Observable Inputs (Level 2) | Asset Backed Securities
Assets
Short-term marketable securities		$ 24,578
[1]	Included in cash and cash equivalents on the balance sheet.

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
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	Sep. 30, 2019	Dec. 31, 2018
Payables And Accruals [Abstract]
Accrued salaries and benefits	$ 674	$ 553
Deferred offering costs	348
Accrued research and development expenses	341	772
Accrued interest	27	29
Other	304	143
Total	$ 1,694	$ 1,497

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	9 Months Ended
	Apr. 30, 2019	Sep. 30, 2019	Sep. 30, 2018
Class Of Stock [Line Items]
Proceeds from issuance of convertible preferred stock, net of issuance costs		$ 61,490	$ 5,986
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Preferred stock, shares issued	6,889,986
Proceeds from issuance of convertible preferred stock, net of issuance costs	$ 61,700
Shares issued price per share	$ 8.95444
Conversion of redeemable convertible preferred stock into common stock, Shares		9,936,341
Redeemable convertible preferred stock outstanding, shares		0

Convertible Preferred Stock - S

Convertible Preferred Stock - Summary of Issued and Outstanding Redeemable Convertible Preferred Stock and Principal Terms (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Class Of Stock [Line Items]
Redeemable Convertible Preferred Stock, Authorized	10,000,000	3,191,489
Redeemable Convertible Preferred Stock, Outstanding	0	3,046,355
Liquidation Value	$ 0	$ 12,134
Carrying Amount		$ 11,648
Series A Convertible Preferred Stock
Class Of Stock [Line Items]
Redeemable Convertible Preferred Stock, Authorized		3,191,489
Redeemable Convertible Preferred Stock, Outstanding		3,046,355
Liquidation Value		$ 12,134
Carrying Amount		$ 11,648
Original Issue Price		$ 3.9833

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) - USD ($)	Oct. 26, 2018	Sep. 30, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt net of debt discount and issuance costs		$ 5,000,000
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		5,100,000
Accrued liabilities related to accretion of final payment included in long-term debt		$ 100,000
Loan Agreement | Silicon Valley Bank | Maximum
Debt Instrument [Line Items]
Accrued liabilities related to accretion of final payment included in long-term debt			$ 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	Sep. 30, 2019USD ($)
Debt Disclosure [Abstract]
2019 remaining three months	$ 167
2020	2,000
2021	2,000
2022	833
Total future maturities of debt	$ 5,000

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock upon exercise of stock options, Shares	267,212
Outstanding Options, Number of Shares, Options granted	1,022,118
Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding Options, Number of Shares, Options granted	1,017,111	402,121
Non-employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Outstanding Options, Number of Shares, Options granted	5,106	0
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	$ 3.41	$ 0.67
Issuance of common stock upon exercise of stock options, Shares	267,212
Unrecognized stock-based compensation expense	$ 3.3
Unrecognized stock-based compensation expense, weighted-average recognition period	3 years 1 month 6 days
Fair value of options vested	$ 0.4	$ 0.1
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 | 10% Stockholder
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options term	5 years
2019 Employee Share Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares reserved for issuance	160,000

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Activity Under Equity Incentive Plans (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2019$ / sharesshares	Dec. 31, 2018$ / sharesshares
Compensation Related Costs [Abstract]
Shares Available for Grant, Balance, January 1, 2019	114,905
Shares Available for Grant, Additional shares authorized	2,675,831
Shares Available for Grant, Options granted	(1,022,118)
Shares Available for Grant, Options cancelled	15,426
Shares Available for Grant, Balance, September 30, 2019	1,784,044	114,905
Shares Available for Grant, Exercisable as of September 30, 2019	341,097
Shares Available for Grant, Vested and expected to vest, September 30, 2019	1,569,257
Outstanding Options, Number of Shares, Balance, January 1, 2019	829,775
Outstanding Options, Number of Shares, Options granted	1,022,118
Outstanding Options, Number of Shares, Options exercised	(267,212)
Outstanding Options, Number of Shares, Options cancelled	(15,424)
Outstanding Options, Number of Shares, Balance, September 30, 2019	1,569,257	829,775
Outstanding Options, Weighted Average Exercise Price, Balance, January 1, 2019 | $ / shares	$ 0.97
Outstanding Options, Weighted Average Exercise Price, Options granted | $ / shares	3.50
Outstanding Options, Weighted Average Exercise Price, Options exercised | $ / shares	1.12
Outstanding Options, Weighted Average Exercise Price, Options cancelled | $ / shares	1.03
Outstanding Options, Weighted Average Exercise Price, Balance, September 30, 2019 | $ / shares	$ 3.50	$ 0.97
Weighted Average Remaining Contractual Term, Balance, January 1, 2019	9 years 1 month 2 days	8 years 9 months 25 days
Weighted Average Remaining Contractual Term, Options granted	9 years 7 months 17 days

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 224	$ 31	$ 422	$ 138
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	106	15	193	84
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 118	$ 16	$ 229	$ 54

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		6 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net loss attributable to common stockholders	$ (8,260)	$ (1,587)	$ (9,106)	$ (3,415)	$ (17,366)	$ (5,002)
Denominator:
Weighted-average shares outstanding	3,670,472	1,115,196			2,006,074	1,061,041
Less: weighted-average unvested restricted shares and shares subject to repurchase	(11,968)	(43,883)			(19,884)	(51,799)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	3,658,504	1,071,313			1,986,190	1,009,242
Net loss per share attributable to common stockholders, basic and diluted	$ (2.26)	$ (1.48)			$ (8.74)	$ (4.96)

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	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding	1,582,352	3,916,024
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	1,569,257	829,775
Unvested Restricted Common Stock Awards
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding	7,979	39,894
Warrants to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities outstanding	5,116

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Details) - USD ($)	Sep. 17, 2019	Apr. 30, 2019	Feb. 28, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2016	Aug. 31, 2016
Related Party Transaction [Line Items]
Conversion of convertible note and accrued interest into preferred stock					$ 134,000
Issuance of common stock upon initial public offering, net of issuance costs				$ 73,748,000
IPO
Related Party Transaction [Line Items]
Issuance of common stock upon initial public offering, net of issuance costs, Shares	6,521,001
Common Stock
Related Party Transaction [Line Items]
Issuance of common stock upon initial public offering, net of issuance costs, Shares				5,500,000
Issuance of common stock upon initial public offering, net of issuance costs				$ 1,000
Common Stock | IPO
Related Party Transaction [Line Items]
Issuance of common stock upon initial public offering, net of issuance costs, Shares	5,500,000
SNBL
Related Party Transaction [Line Items]
Estimated fair value of additional common stock					500,000
Obligation to issue additional common stock reclassified to additional paid-in capital					500,000
SNBL | IPO
Related Party Transaction [Line Items]
Issuance of common stock upon initial public offering, net of issuance costs, Shares	233,333
SNBL | Other Income, Net
Related Party Transaction [Line Items]
Loss on change in fair value of common stock					$ 100,000
SNBL | Common Stock
Related Party Transaction [Line Items]
Issuance of common stock upon initial public offering, net of issuance costs, Shares			476,897
Consideration from issuance of common stock			$ 0
SNBL | Series A Convertible Preferred Stock
Related Party Transaction [Line Items]
Percentage of fully diluted common stock owned						20.00%
SNBL | Series B Convertible Preferred Stock
Related Party Transaction [Line Items]
Issuance of common stock upon initial public offering, net of issuance costs, Shares		307,110
Issuance of common stock upon initial public offering, net of issuance costs		$ 2,700,000
Convertible Note | SNBL
Related Party Transaction [Line Items]
Debt instrument, face amount							$ 100,000
Convertible Note | SNBL | Series A Convertible Preferred Stock
Related Party Transaction [Line Items]
Debt instrument converted, shares issued			33,741
Convertible Note | SNBL | Maximum
Related Party Transaction [Line Items]
Conversion of convertible note and accrued interest into preferred stock			$ 100,000

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Future Minimum Lease Payments Under Non-cancelable Operating Leases (Details) $ in Thousands	Sep. 30, 2019USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2019 remaining three months	$ 73
2020	299
2021	195
2022	83
Total minimum lease payments	$ 650

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Income tax provision	$ 0	$ 0

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended
	Oct. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Subsequent Events [Line Items]
Common stock, shares issued		16,815,569	1,083,280
Subsequent Events | Over-Allotment Option
Subsequent Events [Line Items]
Common stock, shares issued	552,116
Shares issued, price per share	$ 15
Gross proceeds from issuance of common stock	$ 8.3