VYNE Therapeutics (VYNE) 10-Q 31 Oct 19 2019 Q3 Quarterly report Financial data

DEI Document

DEI Document - shares	9 Months Ended
	Sep. 30, 2019	Oct. 15, 2019
Cover [Abstract]
Entity Registrant Name	Menlo Therapeutics Inc.
Entity Central Index Key	0001566044
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Trading Symbol	MNLO
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Quarterly Report	true
Document Transition Report	false
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Document Type	10-Q
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		23,983,751
Entity File Number	001-38356
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	45-3757789
Entity Address, Address Line One	200 Cardinal Way
Entity Address, Address Line Two	2nd Floor
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94063
City Area Code	650
Local Phone Number	486-1416

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 34,244	$ 49,510
Short-term investments	57,112	86,740
Prepaid expenses and other current assets	2,073	3,250
Total current assets	93,429	139,500
Long-term investments	2,004
Property and equipment, net	113	146
Prepaid expenses and other long-term assets	200	282
Right-of-use asset	830
Total assets	96,576	139,928
Current liabilities:
Accounts payable	2,992	3,290
Accrued expenses and other current liabilities	5,719	6,254
Lease liability	741
Total current liabilities	9,452	9,544
Long term lease liability	122
Other non-current liabilities		7
Total liabilities	9,574	9,551
Commitments and contingencies (see Note 7)
Stockholders’ equity:
Preferred stock: $0.0001 par value; 20,000,000 shares authorized at September 30, 2019 and December 31, 2018; no shares issued and outstanding at September 30, 2019 and December 31, 2018
Common stock: $0.0001 par value; 300,000,000 shares authorized at September 30, 2019 and December 31, 2018; 23,983,751 and 23,233,184 shares issued and outstanding at September 30, 2019 and December 31, 2018, respectively	3	3
Additional paid-in capital	249,805	241,106
Accumulated other comprehensive gain (loss)	35	(96)
Accumulated deficit	(162,841)	(110,636)
Total stockholders’ equity	87,002	130,377
Total liabilities and stockholders’ equity	$ 96,576	$ 139,928

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement Of Financial Position [Abstract]
Preferred stock, par value per share (in USD per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (shares)	20,000,000	20,000,000
Preferred stock, shares issued (shares)	0	0
Preferred stock, shares outstanding (shares)	0	0
Common stock, par value per share (in USD per share)	$ 0.0001	$ 0.0001
Common stock authorized (shares)	300,000,000	300,000,000
Common stock issued (shares)	23,983,751	23,233,184
Common stock outstanding (shares)	23,983,751	23,233,184

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Collaboration and license revenue				$ 10,640
Type of Revenue [Extensible List]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development	$ 12,622	$ 10,667	$ 42,003	$ 37,913
General and administrative	4,804	3,035	12,309	8,822
Total operating expenses	17,426	13,702	54,312	46,735
Loss from operations	(17,426)	(13,702)	(54,312)	(36,095)
Interest income and other expense, net	571	855	2,107	2,243
Net loss	(16,855)	(12,847)	(52,205)	(33,852)
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale securities	30	48	131	(50)
Comprehensive loss	$ (16,825)	$ (12,799)	$ (52,074)	$ (33,902)
Net loss attributable to common stockholders per share, basic and diluted	$ (0.70)	$ (0.56)	$ (2.20)	$ (1.60)
Weighted-average number of common shares used to compute basic and diluted net loss per share	23,955,210	22,977,793	23,708,123	21,164,069

Condensed Statements of Convert

Condensed Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	At-The-Market Offering	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Series C Convertible Preferred Stock	Common Stock	Common StockAt-The-Market Offering	Additional Paid-in Capital	Additional Paid-in CapitalAt-The-Market Offering	Accumulated Deficit	Other Comprehensive Loss
Balance, beginning at Dec. 31, 2017	$ (57,034)					$ 1		$ 2,207		$ (59,191)	$ (51)
Preferred stock, beginning (shares) at Dec. 31, 2017			14,300	14,106,583	11,854,463
Preferred stock, beginning at Dec. 31, 2017			$ 14,183	$ 44,820	$ 50,324
Balance, beginning (shares) at Dec. 31, 2017						5,298,593
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of preferred stock to common stock	109,327		$ (14,183)	$ (44,820)	$ (50,324)	$ 1		109,326
Conversion of preferred stock to common stock (shares)			(14,300)	(14,106,583)	(11,854,463)	9,629,405
Issuance of common stock	125,389					$ 1		125,388
Issuance of common stock (shares)						8,050,000
Vesting of early exercised stock options	6							6
Stock-based compensation	822							822
Unrealized gain on available-for-sale securities	(151)										(151)
Net loss	(12,657)									(12,657)
Balance, ending at Mar. 31, 2018	165,702					$ 3		237,749		(71,848)	(202)
Balance, ending (shares) at Mar. 31, 2018						22,977,998
Balance, beginning at Dec. 31, 2017	(57,034)					$ 1		2,207		(59,191)	(51)
Preferred stock, beginning (shares) at Dec. 31, 2017			14,300	14,106,583	11,854,463
Preferred stock, beginning at Dec. 31, 2017			$ 14,183	$ 44,820	$ 50,324
Balance, beginning (shares) at Dec. 31, 2017						5,298,593
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Unrealized gain on available-for-sale securities	(50)
Net loss	(33,852)
Balance, ending at Sep. 30, 2018	146,884					$ 3		240,024		(93,042)	(101)
Balance, ending (shares) at Sep. 30, 2018						23,232,184
Balance, beginning at Mar. 31, 2018	165,702					$ 3		237,749		(71,848)	(202)
Balance, beginning (shares) at Mar. 31, 2018						22,977,998
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock	27							27
Vesting of early exercised stock options	8							8
Stock-based compensation	746							746
Unrealized gain on available-for-sale securities	53										53
Net loss	(8,347)									(8,347)
Balance, ending at Jun. 30, 2018	158,189					$ 3		238,530		(80,195)	(149)
Balance, ending (shares) at Jun. 30, 2018						22,977,998
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock on exercise of stock options	494							494
Issuance of common stock on exercise of stock options (shares)						254,186
Vesting of early exercised stock options	6							6
Stock-based compensation	994							994
Unrealized gain on available-for-sale securities	48										48
Net loss	(12,847)									(12,847)
Balance, ending at Sep. 30, 2018	146,884					$ 3		240,024		(93,042)	(101)
Balance, ending (shares) at Sep. 30, 2018						23,232,184
Balance, beginning at Dec. 31, 2018	130,377					$ 3		241,106		(110,636)	(96)
Balance, beginning (shares) at Dec. 31, 2018						23,233,184
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock on exercise of stock options	83							83
Issuance of common stock on exercise of stock options (shares)						34,418
Issuance of common stock under Employee Stock Purchase Plan	300							300
Issuance of common stock under Employee Stock Purchase Plan, (shares)						46,019
Issuance of common stock		$ 2,632							$ 2,632
Issuance of common stock (shares)							358,614
Vesting of early exercised stock options	7							7
Stock-based compensation	1,019							1,019
Unrealized gain on available-for-sale securities	86										86
Net loss	(18,873)									(18,873)
Balance, ending at Mar. 31, 2019	115,631					$ 3		245,147		(129,509)	(10)
Balance, ending (shares) at Mar. 31, 2019						23,672,235
Balance, beginning at Dec. 31, 2018	$ 130,377					$ 3		241,106		(110,636)	(96)
Balance, beginning (shares) at Dec. 31, 2018						23,233,184
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock on exercise of stock options (shares)	60,347
Unrealized gain on available-for-sale securities	$ 131
Net loss	(52,205)
Balance, ending at Sep. 30, 2019	87,002					$ 3		249,805		(162,841)	35
Balance, ending (shares) at Sep. 30, 2019						23,983,751
Balance, beginning at Mar. 31, 2019	115,631					$ 3		245,147		(129,509)	(10)
Balance, beginning (shares) at Mar. 31, 2019						23,672,235
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock on exercise of stock options	71							71
Issuance of common stock on exercise of stock options (shares)						25,746
Issuance of common stock	1,864							1,864
Issuance of common stock (shares)						246,416
Vesting of early exercised stock options	5							5
Stock-based compensation	1,068							1,068
Unrealized gain on available-for-sale securities	15										15
Net loss	(16,477)									(16,477)
Balance, ending at Jun. 30, 2019	102,177					$ 3		248,155		(145,986)	5
Balance, ending (shares) at Jun. 30, 2019						23,944,397
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock on exercise of stock options (shares)						183
Issuance of common stock under Employee Stock Purchase Plan	129							129
Issuance of common stock under Employee Stock Purchase Plan, (shares)						30,679
Issuance of common stock		$ 42							$ 42
Issuance of common stock (shares)							8,492
Vesting of early exercised stock options	6							6
Stock-based compensation	1,503							1,473
Unrealized gain on available-for-sale securities	30										30
Net loss	(16,855)									(16,855)
Balance, ending at Sep. 30, 2019	$ 87,002					$ 3		$ 249,805		$ (162,841)	$ 35
Balance, ending (shares) at Sep. 30, 2019						23,983,751

Condensed Statement of Cash Flo

Condensed Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net loss	$ (52,205)	$ (33,852)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	43	10
Amortization of right-of-use-asset	484
Amortization of premium on investment securities	(554)	(551)
Stock-based compensation expense	3,560	2,564
Change in operating assets and liabilities:
Accounts receivable		786
Prepaid expenses and other current assets	1,177	1,763
Prepaid expenses and other long-term assets	82	(354)
Accounts payable	(298)	240
Accrued expenses and other current liabilities	(517)	1,819
Lease liability	(452)
Deferred revenue		(8,531)
Other non-current liabilities	(7)	(10)
Net cash used in operating activities	(48,687)	(36,116)
Investing activities
Purchase of property plant and equipment	(11)	(118)
Purchase of investments	(78,346)	(109,952)
Proceeds from sales of investments	14,042	5,100
Proceeds from maturities of investments	92,615	75,165
Net cash provided by (used in) investing activities	28,300	(29,805)
Financing activities
Proceeds from issuance of common stock, net of issuance costs	4,538	125,417
Proceeds from purchases under the Employee Stock Purchase Plan	429
Proceeds from the exercise of stock options	154	494
Net cash provided by financing activities	5,121	125,911
Net (decrease) increase in cash and cash equivalents	(15,266)	59,990
Cash and cash equivalents at beginning of period	49,510	10,206
Cash and cash equivalents at end of period	34,244	70,196
Non-cash financing activities
Addition of right-of-use-asset	$ 1,314
Conversion of preferred stock to common stock		$ 109,327

Formation and Business of the C

Formation and Business of the Company	9 Months Ended
	Sep. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Formation and Business of the Company	1. Formation and Business of the Company Menlo Therapeutics Inc. (the “Company”) is a late‑stage biopharmaceutical company focused on the development and commercialization of serlopitant for the treatment of pruritus, or itch, associated with various conditions such as prurigo nodularis, or PN, psoriasis and chronic pruritus of unknown origin, or CPUO. The Company believes serlopitant, a highly selective small molecule inhibitor of the neurokinin 1 receptor, or NK 1 ‑R The Company was incorporated in Delaware in October 2011. Since commencing operations, the Company has devoted substantially all of its resources to developing its product candidate, serlopitant, including conducting clinical trials and providing general and administrative support for these operations. Shelf Registration Statement and At-the-Market Offering On February 1, 2019, the Company filed a shelf registration statement on Form S-3, which permitted: (a) the offering, issuance and sale by the Company of up to a maximum aggregate offering price of $150.0 million of its common stock, preferred stock, debt securities, warrants, purchase contracts and/or units; and (b) as part of the $150.0 million, the offering, issuance and sale by the Company of up to a maximum aggregate offering price of $50.0 million of its common stock that may be issued and sold under a sales agreement with Cantor Fitzgerald & Co in one or more at-the-market offerings During the nine months ended September 30, 2019, the Company issued 613,522 shares of its common stock pursuant to the Company’s at-the-market offering program for aggregate net proceeds of $4.8 million after $0.1 million of commission and before $0.2 million of offering costs. Initial Public Offering In January 2018, the Company completed its initial public offering (“IPO”) of shares of its common stock, pursuant to which the Company issued 8,050,000 shares of common stock, which includes 1,050,000 shares issued pursuant to the underwriter’s option to purchase additional shares, and received net proceeds of approximately $125.4 million, after deducting underwriting discounts, commissions and offering expenses. In connection with the completion of the Company's IPO, all shares of convertible preferred stock converted into 9,629,405 shares of common stock. Liquidity and Capital Resources The accompanying financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the settlement of liabilities and commitments in the normal course of business. The financial statements do not reflect any adjustments relating to the recoverability and classification of assets and liabilities that might be necessary if the Company is unable to continue as a going concern. Since inception, the Company has incurred losses and negative cash flows from operations. For the nine months ended September 30, 2019, the Company incurred a net loss of $52.2 million and used Management expects to continue to incur additional substantial losses in the foreseeable future as the Company continues its development, seeks regulatory approval of, and, if approved, begins to commercialize serlopitant. Management plans to finance operations through equity or debt financings or other capital sources, including potential collaborations or other strategic transactions. There can be no assurances that, in the event that the Company requires additional financing, such financing will be available on terms which are favorable to the Company, or at all. If the Company is unable to raise additional funding to meet its working capital needs in the future, it will be forced to delay or reduce the scope of its research programs and/or limit or cease its operations. The Company believes that its existing cash, cash equivalents and investments as of September 30, 2019 will provide sufficient funds to enable it to meet its obligations for at least the next 12 months from the issuance of our financial statements as of and for the three and nine months ended September 30, 2019.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	2. Significant Accounting Policies Basis of Presentation The accompanying financial information for the three and nine months ended September 30, 2019 Segments The Company operates in one segment. Management uses one measurement of profitability and does not segregate its business for internal reporting. All long‑lived assets are maintained in the United States of America. Use of Estimates Preparation of financial statements in conformity with U.S. Generally Accepted Accounting Principles, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of expenses during the reporting periods covered by the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, stock‑based compensation expense, the resolution of uncertain tax positions and valuation allowance and accruals for research and development costs. Management bases its estimates on historical experience or various assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates. Research and Development Expenses Research and development costs are expensed as incurred. Substantially all of the Company’s research and development expenses consist of expenses incurred in connection with the development of serlopitant. These expenses include certain payroll and personnel expenses including stock‑based compensation expense, consulting costs, contract manufacturing costs and fees paid to clinical research organizations, or CROs, to conduct research and development. Non-refundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized and recognized as an expense as the goods are delivered or the related services are performed. The Company estimates non‑clinical study, contract manufacturing, and clinical trial expenses based on the services performed pursuant to contracts with research institutions and clinical research organizations that conduct and manage non‑clinical studies and clinical trials on its behalf. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the receipt of the related services are recorded as prepaid expenses until the services are rendered. Leases On January 1, 2019, the Company adopted Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 842, Leases (“ASC 842”), using the modified retrospective method for all lease arrangements at the beginning of the period of adoption. Results for reporting periods beginning January 1, 2019 are presented under ASC 842, while prior period amounts were not adjusted and continue to be presented in accordance with the Company’s historical accounting under ASC Topic 840, Leases. ASC 842 had an impact on the Company’s condensed balance sheet but did not have a significant impact on the Company’s net loss. Under ASC 842, the Company determines if an arrangement is a lease at inception. in determining the present value of lease payments Stock-Based Compensation The Company maintains an equity incentive plan under which incentive stock options, restricted stock awards, and restricted stock units may be granted to employees, directors, and non-employees. In addition, the Company maintains an employee stock purchase plan (“ESPP”) under which employees may purchase shares of our common stock through payroll deductions. The fair value of options to purchase common stock granted to employees, directors and non-employees is estimated on the grant date using the Black‑Scholes option valuation model. The calculation of stock‑based compensation expense requires that the Company make certain assumptions and judgments about a number of complex and subjective variables used in the Black‑Scholes model, including the expected term, expected volatility of the underlying common stock, and risk‑free interest rate. Such value is recognized as an expense over the requisite service period using the straight-line method. The fair value of restricted stock units used in the Company’s expense recognition method is based on the closing price of the Company’s common stock on the date of the grant. Such value is recognized as an expense over the requisite service period using the straight-line method. Stock-based compensation expense related to the ESPP is recognized based on the fair value of each award estimated on the first day of the offering period using the Black-Scholes option pricing model and recorded as expense over the service period using the straight-line method. In June 2018, the FASB issued ASU 2018-07 Improvements to Nonemployee Share-Based Payment Accounting (Topic 718) Revenue Recognition The Company records revenue based on a five-step model in accordance with ASC 606, Revenue from Contracts with Customers ("ASC 606"). For the Company’s collaboration agreement, which is discussed further under Note 5, the Company identifies the performance obligations, determines the transaction price, allocates the contract transaction price to the performance obligations, and recognizes the revenue when (or as) the performance obligation is satisfied. The Company identifies the performance obligations included within the agreement and evaluates which performance obligations are distinct. Upfront payments for licenses are evaluated to determine if the license is capable of being distinct from the obligations of the Company to participate on certain development and/or commercialization committees with the collaboration partners and supply manufactured drug product for clinical trials. For performance obligations that the Company satisfies over time, the Company utilizes the input method and revenue is recognized by consistently applying a method of measuring progress toward complete satisfaction of that performance obligation. The Company periodically reviews its estimated periods of performance based on the progress under each arrangement and accounts for the impact of any changes in estimated periods of performance on a prospective basis. Milestone payments are a form of variable consideration as the payments are contingent upon achievement of a substantive event. Milestone payments are estimated and included in the transaction price when the Company determines that it is probable that there will not be a significant reversal of cumulative revenue recognized in future periods. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such milestones and any related constraint, and if necessary, adjusts the estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration or other revenues and earnings in the period of adjustment. Research and development revenues and cost reimbursements are based upon negotiated rates for the Company’s full-time employee equivalents (“FTE”) and actual out-of-pocket costs. FTE rates are set based upon the Company’s costs, and which the Company believes approximate fair value. None of the revenues recognized to date are refundable if the relevant research effort is not successful. In accordance with ASC 606, the Company is required to adjust the transaction price for the effects of the time value of money if the timing of payments agreed to by the parties to the contract, explicitly or implicitly, provides the Company or its customer with a significant benefit of financing the transfer of goods or services. The Company concluded that its collaboration agreement did not contain a significant financing component because the payment structure of its agreements arise from reasons other than providing a significant benefit of financing. Net Loss per Share of Common Stock Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted‑average number of common shares outstanding during the period, without consideration for 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 shares and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, convertible preferred stock and common stock options are considered to be potentially dilutive securities. Because the Company has reported a net loss for the three and nine months ended September 30, 2019 and 2018 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 (unaudited) (unaudited) Numerator: Net loss attributable to common stockholders, basic and diluted $ (16,855 ) $ (12,847 ) $ (52,205 ) $ (33,852 ) Denominator: Weighted-average common shares outstanding 23,961,823 23,063,757 23,734,573 21,269,957 Less: weighted-average common shares subject to repurchase (6,613 ) (85,964 ) (26,450 ) (105,888 ) Weighted-average common shares used to compute basic and diluted net loss per share 23,955,210 22,977,793 23,708,123 21,164,069 Net loss per share attributable to common stockholders Basic and diluted $ (0.70 ) $ (0.56 ) $ (2.20 ) $ (1.60 ) 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 periods presented because including them would have been antidilutive: September 30, 2019 2018 (unaudited) Stock options available for issuance 937,566 2,195,901 Stock options outstanding 4,168,284 3,050,067 Restricted stock 966,040 — Outstanding common stock subject to repurchase — 79,351 Shares issuable related to ESPP 480,634 59,735 Total 6,552,524 5,385,054 Other Significant Accounting Policies The Company’s significant accounting policies are described in Note 2 to our financial statements for the year ended December 31, 2018, included in our Annual Report on Form 10-K. There have been no material changes to the Company’s significant accounting policies during the nine months ended September 30, 2019, except as noted below with respect to the Company’s adoption of ASC 842. Recent Accounting Pronouncements In February 2016, the FASB issued Accounting Standards Update (“ASU”) 2016‑02, Leases Targeted Improvements to ASC 842 In June 2016, the FASB issued ASU 2016-13, Financial Instruments — Credit Losses — Measurement of Credit Losses on Financial Instruments The Company does not expect the adoption of this final rule to have a material impact on it’s condensed financial statements. In June 2018, the FASB issued ASU 2018-07 Improvements to Nonemployee Share-Based Payment Accounting (Topic 718) In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820)

Cash Equivalents and Investment

Cash Equivalents and Investments	9 Months Ended
	Sep. 30, 2019
Investments Debt And Equity Securities [Abstract]
Cash Equivalents and Investments	3. Cash Equivalents and Investments At September 30, 2019 and December 31, 2018, the balance in the Company’s accumulated other comprehensive gain (loss) was comprised solely of activity related to the Company’s available‑for‑sale securities. There were no material realized gains or losses recognized on the sale or maturity of available‑for‑sale securities during the three and nine months ended September 30, 2019 and September 30, 2018 The following table summarizes the cash and available‑for‑sale securities (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Fair Value September 30, 2019 (unaudited) Cash and money market funds $ 16,075 $ — $ — $ 16,075 Corporate notes 30,610 35 — 30,645 Commercial paper 32,438 — (2 ) 32,436 Agency bonds 2,000 — (1 ) 1,999 Asset backed securities 1,199 1 — 1,200 Government notes 11,003 3 (1 ) 11,005 Total $ 93,325 $ 39 $ (4 ) $ 93,360 Reported as: Cash and cash equivalents 34,244 Short-term investments 57,112 Long-term investments 2,004 Total $ 93,360 Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2018: Cash and money market funds $ 7,490 $ — $ — $ 7,490 Corporate notes 41,103 2 (70 ) 41,035 Commercial paper 63,036 — — 63,036 Asset backed securities 12,236 — (23 ) 12,213 Government notes 12,481 — (5 ) 12,476 Total $ 136,346 $ 2 $ (98 ) $ 136,250 Reported as: Cash and cash equivalents 49,510 Short-term investments 86,740 Total $ 136,250

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The fair value of the Company’s financial instruments reflects the amounts that the Company estimates it would receive in connection with the sale of an asset or pay in connection with the transfer of a liability in an orderly transaction between market participants at the measurement date (exit price). The Company discloses and recognizes the fair value of its assets and liabilities using a hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to valuations based upon unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to valuations based upon unobservable inputs that are significant to the valuation (Level 3 measurements). The guidance establishes three levels of the fair value hierarchy as follows: Level 1 – Inputs that reflect unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date; Level 2 – Inputs other than quoted prices that are observable for the assets or liability either directly or indirectly, including inputs in markets that are not considered to be active; Level 3 – Inputs that are unobservable. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. During the periods presented, the Company has not changed the manner in which it values assets and liabilities that are measured at fair value using Level 3 inputs. The Company recognizes transfers between levels of the fair value hierarchy as of the end of the reporting period. There were no transfers within the hierarchy during the periods presented. A summary of the assets and liabilities carried at fair value in accordance with the hierarchy defined above is as follows (in thousands): Fair Value Measurements Using Level 1 Level 2 Level 3 Total September 30, 2019 (unaudited) Assets: Money market funds $ 12,772 $ — $ — $ 12,772 Corporate notes — 30,645 — 30,645 Commercial paper — 32,436 — 32,436 Agency bonds — 1,999 — 1,999 Asset backed securities — 1,200 — 1,200 Government notes — 11,005 — 11,005 Total assets $ 12,772 $ 77,285 — $ 90,057 Fair Value Measurements Using Level 1 Level 2 Level 3 Total December 31, 2018: Assets: Money market funds $ 5,802 $ — $ — $ 5,802 Corporate notes — 41,035 — 41,035 Commercial paper — 63,036 — 63,036 Asset backed securities — 12,213 — 12,213 Government notes — 12,476 — 12,476 Total assets $ 5,802 $ 128,760 $ — $ 134,562 The Company uses a market approach for determining the fair value of all its Level 1 and Level 2 money market funds and marketable securities. To value its money market funds, the Company values the funds at $1 stable net asset value, which is the market pricing convention for identical assets that the Company has the ability to access.

License Agreements

License Agreements	9 Months Ended
	Sep. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
License Agreements	5. License Agreements Merck License In December 2012, the Company entered into an exclusive worldwide royalty free license agreement with Merck Sharp & Dohme Corp. (“Merck”) for exclusive worldwide rights for the development and commercialization of serlopitant and two other NK 1 ‑R In May 2018, the Company paid a $3.0 million milestone payment associated with the initiation of the Company’s Phase 3 clinical program for pruritus associated with prurigo nodularis. Future milestone payments are considered a form of variable consideration and accrued for when the Company determines that it is probable that there will not be a significant reversal of the accrual in future periods. JT Torii Collaboration Agreement In August 2016, the Company entered into a license and collaboration agreement (the “Collaboration Agreement”) with Japan Tobacco Inc. and Torii Pharmaceutical Co. Ltd. (together referred to as “JT Torii”). Under the Collaboration Agreement, the Company granted to JT Torii the rights to develop and commercialize products containing serlopitant in Japan, for the treatment of diseases and conditions other than nausea or vomiting. In exchange, JT Torii paid the Company an upfront, non‑refundable payment of $11.0 million. In addition, the Company was entitled to receive aggregate payments of up to $28.0 million upon the achievement of specified development and regulatory milestones, and $15.0 million upon the achievement of a commercial milestone, as well as tiered royalties from the mid-single digits up to the mid‑teens on sales of licensed products in Japan. The Company’s performance obligations under the license agreement included the transfer of intellectual property rights in the form of licenses, obligations to participate on certain development and/or commercialization committees with the collaboration partners and supply manufactured drug product for clinical trials. In the second quarter of 2018, JT Torii informed the Company that they decided to halt the Japanese Phase 2 clinical trial of serlopitant, following which the Company and JT Torii agreed to terminate the Collaboration Agreement. As a result, the Company has reacquired full ownership of the development and commercialization rights to serlopitant in Japan and Under the Collaboration Agreement, the Company was reimbursed by JT Torii for the non-commercial supplies of serlopitant at the same rate it was charged by the third-party manufacturer for such supplies, which price did not include a significant or incremental discount for JT Torii. The assessment of performance obligations required judgment in order to determine the allocation of revenue to each deliverable and the appropriate period of time over which the revenue should be recognized. Under the Collaboration Agreement, the Company determined that the license was not distinct from the research and development services because JT Torii could not use the license with its available resources to obtain any economic value without the Company’s participation. The license and the services were combined as one unit of accounting and upfront payments were recorded initially as deferred revenue in the balance sheet. Revenue was then recognized over an estimated performance period as performance of services was being completed. The Company recognized the upfront fee based on performance of the obligation using input method over the period of performance, which represented the estimated development period in the territories based on the initial development plan managed by the joint steering committee. The original term of the agreement was through the expiration of the patents associated with serlopitant. Under the Collaboration Agreement, two of the milestones, which amount to $2.0 million each, related to the preparation of an IND for submission to regulatory authorities in the territory were considered substantive given that they are triggered by the Company’s performance relative to the achievement of pre-specified, “at risk” milestone events, including the submission of all completed trials clinical data packages and the validation of the manufacturing process. On September 1, 2017, the Company entered into a new services agreement with JT Torii to provide research and development services, including regulatory, chemistry and manufacturing support and related materials that is distinct from the original Collaboration Agreement. The Company evaluated the new services agreement and determined that the research and materials delivered to JT Torii represented another contract that provides distinct goods and services to JT Torii. The fees received under the services agreement were recognized as and when such services were performed by the Company and JT Torii consumed the benefits of those services. During the three and nine months ended September 30, 2018

Balance Sheets Components

Balance Sheets Components	9 Months Ended
	Sep. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheets Components	6. Balance Sheets Components Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, 2019 December 31, 2018 (unaudited) Accrued personnel expenses $ 1,679 $ 2,649 Accrued clinical and development expenses 3,645 3,349 Other 395 256 Total $ 5,719 $ 6,254

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	Legal Matters The Company’s industry is characterized by frequent claims and litigation, including claims regarding intellectual property. As a result, the Company may be subject to various legal proceedings from time to time. The results of any future litigation cannot be predicted with certainty, and regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources and other factors. On November 8, 2018, a putative securities class action complaint captioned Pavel Savelstrov v. Menlo Therapeutics, Inc., et al., Case No.18-CIV-06049, was filed in state court in the Superior Court of the State of California, County of San Mateo, against the Company, certain of its current executive officers and its directors, and certain underwriters in the Company’s initial public offering. On January 28, 2019, a putative securities class action complaint captioned Hugh McKay v. Menlo Therapeutics, Inc., et al. The complaints alleged violations of Sections 11, 12(a)(2) and 15 of the Securities Act of 1933 due to allegedly false and misleading statements in connection with the Company’s initial public offering. The McKay action has been consolidated with the Savelstrov action and the claim for violations of Section 12(a)(2) has been dismissed. The Company believes that the lawsuits are without merit and intends to vigorously defend itself. Accordingly, the Company cannot reasonably estimate any range of potential future charges, and the Company has not recorded any accrual for a contingent liability associated with these legal proceedings. Leases In September 2017, the Company entered into a lease agreement for its current location. The thirty-month lease, began on October 1, 2017 and provides approximately 14,000 square feet of office space in Redwood City, California. Base annual rent at lease inception was approximately $55,000 per month with annual increases. On April 12, 2019, the Company entered into an amendment to its lease agreement for its current location, which was effective on April 23, 2019, the date landlord consent was received. Under the amendment, the lease was extended for an additional nine months, from March 31, 2020 to December 31, 2020. The base rent during the extended term will be approximately $60,000 per month. The Company recognizes rent expense on a straight‑line basis over the respective lease period. Lease expense was $0.2 million and $0.5 million, respectively, for the three and nine months ended September 30, 2019 and $0.2 and $0.6 million, respectively, for the three and nine months ended September 30, 2018. 2019 (remaining) $ 179 2020 732 Present value adjustment (48 ) Present value of lease payments $ 863 Lease liability $ 741 Long term lease liability 122 Present value of lease payments $ 863 Indemnification As permitted under Delaware law and in accordance with the Company’s bylaws, the Company is required to indemnify its officers and directors for certain events or occurrences while the officer or director is or was serving in such capacity. The Company is also party to indemnification agreements with its directors. The Company believes the fair value of the indemnification rights and agreements is minimal. Accordingly, the Company has not recorded any liabilities for these indemnification rights and agreements as of September 30, 2019 and December 31, 2018. Contingencies From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of its business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made, and such expenditures can be reasonably estimated. Management is not currently aware of any matters that could have a material adverse effect on the financial position, results of operations, or cash flows of the Company.

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stockholders' Equity	Equity Incentive Plans Under the Company’s 2011 Stock Incentive Plan (the “2011 Plan”), the Company may grant options to purchase common stock, restricted stock awards, or directly issue shares of common stock to employees, directors and consultants of the Company. Under the 2011 Plan, options granted are exercisable over a maximum term of 10 years from the date of grant and generally vest over a period of four years. Following the closing of the Company’s initial public offering in January 2018, the Company has retired and has made no further awards under the 2011 Plan. The Company adopted a 2018 Omnibus Incentive Plan (the “2018 Plan”), effective January 2018. The 2018 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock, restricted stock units, dividend equivalent rights and other stock and cash-based awards (including annual cash incentives and long-term cash incentives). Pursuant to the terms of the 2018 Plan in January 2019, the 2018 Plan share reserve automatically increased by 929,327 shares of common stock issuable. The Company adopted a 2018 Employee Stock Purchase Plan (“ESPP”) in January 2018. The ESPP enables eligible employees of the Company and designated affiliates to purchase shares of common stock at a discount of 15%. Six-month offer periods under the ESPP commenced on September 1, 2018. Pursuant to the terms of the ESPP in January 2019, the ESPP share reserve automatically increased by 232,332 shares of common stock. Total stock-based compensation expense for employees and non-employees recognized in the statements of operations was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (unaudited) (unaudited) Research and development $ 636 $ 475 $ 1,660 $ 1,217 General and administrative 837 519 1,900 1,347 Total stock-based compensation expense $ 1,473 $ 994 $ 3,560 $ 2,564 The table below summarizes stock option activity under the 2011 Plan and 2018 Plan: Number of Shares Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (in thousands) Balances at December 31, 2018 3,905,470 $ 5.35 8.65 $ 2,509 Forfeited/expired (197,689 ) 9.38 Exercised (60,347 ) 2.54 254 Granted 520,850 5.97 Balances at September 30, 2019 4,168,284 $ 5.27 8.06 $ 2,816 During the three and nine months ended September 30, 2019, the Company granted 966,040 restricted stock units, which had a weighted-average award date fair value of $4.08 per share.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial information for the three and nine months ended September 30, 2019
Segments	Segments The Company operates in one segment. Management uses one measurement of profitability and does not segregate its business for internal reporting. All long‑lived assets are maintained in the United States of America.
Use of Estimates	Use of Estimates Preparation of financial statements in conformity with U.S. Generally Accepted Accounting Principles, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of expenses during the reporting periods covered by the financial statements and accompanying notes. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, stock‑based compensation expense, the resolution of uncertain tax positions and valuation allowance and accruals for research and development costs. Management bases its estimates on historical experience or various assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ materially from those estimates.
Research and Development Expenses	Research and Development Expenses Research and development costs are expensed as incurred. Substantially all of the Company’s research and development expenses consist of expenses incurred in connection with the development of serlopitant. These expenses include certain payroll and personnel expenses including stock‑based compensation expense, consulting costs, contract manufacturing costs and fees paid to clinical research organizations, or CROs, to conduct research and development. Non-refundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized and recognized as an expense as the goods are delivered or the related services are performed. The Company estimates non‑clinical study, contract manufacturing, and clinical trial expenses based on the services performed pursuant to contracts with research institutions and clinical research organizations that conduct and manage non‑clinical studies and clinical trials on its behalf. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from the estimate, the Company will adjust the accrual accordingly. Payments made to third parties under these arrangements in advance of the receipt of the related services are recorded as prepaid expenses until the services are rendered.
Leases	Leases On January 1, 2019, the Company adopted Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 842, Leases (“ASC 842”), using the modified retrospective method for all lease arrangements at the beginning of the period of adoption. Results for reporting periods beginning January 1, 2019 are presented under ASC 842, while prior period amounts were not adjusted and continue to be presented in accordance with the Company’s historical accounting under ASC Topic 840, Leases. ASC 842 had an impact on the Company’s condensed balance sheet but did not have a significant impact on the Company’s net loss. Under ASC 842, the Company determines if an arrangement is a lease at inception. in determining the present value of lease payments
Stock-Based Compensation	Stock-Based Compensation The Company maintains an equity incentive plan under which incentive stock options, restricted stock awards, and restricted stock units may be granted to employees, directors, and non-employees. In addition, the Company maintains an employee stock purchase plan (“ESPP”) under which employees may purchase shares of our common stock through payroll deductions. The fair value of options to purchase common stock granted to employees, directors and non-employees is estimated on the grant date using the Black‑Scholes option valuation model. The calculation of stock‑based compensation expense requires that the Company make certain assumptions and judgments about a number of complex and subjective variables used in the Black‑Scholes model, including the expected term, expected volatility of the underlying common stock, and risk‑free interest rate. Such value is recognized as an expense over the requisite service period using the straight-line method. The fair value of restricted stock units used in the Company’s expense recognition method is based on the closing price of the Company’s common stock on the date of the grant. Such value is recognized as an expense over the requisite service period using the straight-line method. Stock-based compensation expense related to the ESPP is recognized based on the fair value of each award estimated on the first day of the offering period using the Black-Scholes option pricing model and recorded as expense over the service period using the straight-line method. In June 2018, the FASB issued ASU 2018-07 Improvements to Nonemployee Share-Based Payment Accounting (Topic 718)
Revenue Recognition	Revenue Recognition The Company records revenue based on a five-step model in accordance with ASC 606, Revenue from Contracts with Customers ("ASC 606"). For the Company’s collaboration agreement, which is discussed further under Note 5, the Company identifies the performance obligations, determines the transaction price, allocates the contract transaction price to the performance obligations, and recognizes the revenue when (or as) the performance obligation is satisfied. The Company identifies the performance obligations included within the agreement and evaluates which performance obligations are distinct. Upfront payments for licenses are evaluated to determine if the license is capable of being distinct from the obligations of the Company to participate on certain development and/or commercialization committees with the collaboration partners and supply manufactured drug product for clinical trials. For performance obligations that the Company satisfies over time, the Company utilizes the input method and revenue is recognized by consistently applying a method of measuring progress toward complete satisfaction of that performance obligation. The Company periodically reviews its estimated periods of performance based on the progress under each arrangement and accounts for the impact of any changes in estimated periods of performance on a prospective basis. Milestone payments are a form of variable consideration as the payments are contingent upon achievement of a substantive event. Milestone payments are estimated and included in the transaction price when the Company determines that it is probable that there will not be a significant reversal of cumulative revenue recognized in future periods. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such milestones and any related constraint, and if necessary, adjusts the estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration or other revenues and earnings in the period of adjustment. Research and development revenues and cost reimbursements are based upon negotiated rates for the Company’s full-time employee equivalents (“FTE”) and actual out-of-pocket costs. FTE rates are set based upon the Company’s costs, and which the Company believes approximate fair value. None of the revenues recognized to date are refundable if the relevant research effort is not successful. In accordance with ASC 606, the Company is required to adjust the transaction price for the effects of the time value of money if the timing of payments agreed to by the parties to the contract, explicitly or implicitly, provides the Company or its customer with a significant benefit of financing the transfer of goods or services. The Company concluded that its collaboration agreement did not contain a significant financing component because the payment structure of its agreements arise from reasons other than providing a significant benefit of financing.
Net Loss per Share of Common Stock	Net Loss per Share of Common Stock Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted‑average number of common shares outstanding during the period, without consideration for 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 shares and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, convertible preferred stock and common stock options are considered to be potentially dilutive securities. Because the Company has reported a net loss for the three and nine months ended September 30, 2019 and 2018 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 (unaudited) (unaudited) Numerator: Net loss attributable to common stockholders, basic and diluted $ (16,855 ) $ (12,847 ) $ (52,205 ) $ (33,852 ) Denominator: Weighted-average common shares outstanding 23,961,823 23,063,757 23,734,573 21,269,957 Less: weighted-average common shares subject to repurchase (6,613 ) (85,964 ) (26,450 ) (105,888 ) Weighted-average common shares used to compute basic and diluted net loss per share 23,955,210 22,977,793 23,708,123 21,164,069 Net loss per share attributable to common stockholders Basic and diluted $ (0.70 ) $ (0.56 ) $ (2.20 ) $ (1.60 ) 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 periods presented because including them would have been antidilutive: September 30, 2019 2018 (unaudited) Stock options available for issuance 937,566 2,195,901 Stock options outstanding 4,168,284 3,050,067 Restricted stock 966,040 — Outstanding common stock subject to repurchase — 79,351 Shares issuable related to ESPP 480,634 59,735 Total 6,552,524 5,385,054
Other Significant Accounting Policies	Other Significant Accounting Policies The Company’s significant accounting policies are described in Note 2 to our financial statements for the year ended December 31, 2018, included in our Annual Report on Form 10-K. There have been no material changes to the Company’s significant accounting policies during the nine months ended September 30, 2019, except as noted below with respect to the Company’s adoption of ASC 842.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the FASB issued Accounting Standards Update (“ASU”) 2016‑02, Leases Targeted Improvements to ASC 842 In June 2016, the FASB issued ASU 2016-13, Financial Instruments — Credit Losses — Measurement of Credit Losses on Financial Instruments The Company does not expect the adoption of this final rule to have a material impact on it’s condensed financial statements. In June 2018, the FASB issued ASU 2018-07 Improvements to Nonemployee Share-Based Payment Accounting (Topic 718) In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820)

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	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 (unaudited) (unaudited) Numerator: Net loss attributable to common stockholders, basic and diluted $ (16,855 ) $ (12,847 ) $ (52,205 ) $ (33,852 ) Denominator: Weighted-average common shares outstanding 23,961,823 23,063,757 23,734,573 21,269,957 Less: weighted-average common shares subject to repurchase (6,613 ) (85,964 ) (26,450 ) (105,888 ) Weighted-average common shares used to compute basic and diluted net loss per share 23,955,210 22,977,793 23,708,123 21,164,069 Net loss per share attributable to common stockholders Basic and diluted $ (0.70 ) $ (0.56 ) $ (2.20 ) $ (1.60 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings 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 periods presented because including them would have been antidilutive: September 30, 2019 2018 (unaudited) Stock options available for issuance 937,566 2,195,901 Stock options outstanding 4,168,284 3,050,067 Restricted stock 966,040 — Outstanding common stock subject to repurchase — 79,351 Shares issuable related to ESPP 480,634 59,735 Total 6,552,524 5,385,054

Cash Equivalents and Investme_2

Cash Equivalents and Investments (Tables)	9 Months Ended
	Sep. 30, 2019
Investments Debt And Equity Securities [Abstract]
Summary of Cash and Available-for-sale Securities	The following table summarizes the cash and available‑for‑sale securities (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Fair Value September 30, 2019 (unaudited) Cash and money market funds $ 16,075 $ — $ — $ 16,075 Corporate notes 30,610 35 — 30,645 Commercial paper 32,438 — (2 ) 32,436 Agency bonds 2,000 — (1 ) 1,999 Asset backed securities 1,199 1 — 1,200 Government notes 11,003 3 (1 ) 11,005 Total $ 93,325 $ 39 $ (4 ) $ 93,360 Reported as: Cash and cash equivalents 34,244 Short-term investments 57,112 Long-term investments 2,004 Total $ 93,360 Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2018: Cash and money market funds $ 7,490 $ — $ — $ 7,490 Corporate notes 41,103 2 (70 ) 41,035 Commercial paper 63,036 — — 63,036 Asset backed securities 12,236 — (23 ) 12,213 Government notes 12,481 — (5 ) 12,476 Total $ 136,346 $ 2 $ (98 ) $ 136,250 Reported as: Cash and cash equivalents 49,510 Short-term investments 86,740 Total $ 136,250

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair Value Disclosures [Abstract]
Summary of Assets and Liabilities Carried at Fair Value	A summary of the assets and liabilities carried at fair value in accordance with the hierarchy defined above is as follows (in thousands): Fair Value Measurements Using Level 1 Level 2 Level 3 Total September 30, 2019 (unaudited) Assets: Money market funds $ 12,772 $ — $ — $ 12,772 Corporate notes — 30,645 — 30,645 Commercial paper — 32,436 — 32,436 Agency bonds — 1,999 — 1,999 Asset backed securities — 1,200 — 1,200 Government notes — 11,005 — 11,005 Total assets $ 12,772 $ 77,285 — $ 90,057 Fair Value Measurements Using Level 1 Level 2 Level 3 Total December 31, 2018: Assets: Money market funds $ 5,802 $ — $ — $ 5,802 Corporate notes — 41,035 — 41,035 Commercial paper — 63,036 — 63,036 Asset backed securities — 12,213 — 12,213 Government notes — 12,476 — 12,476 Total assets $ 5,802 $ 128,760 $ — $ 134,562

Balance Sheets Components (Tabl

Balance Sheets Components (Tables)	9 Months Ended
	Sep. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): September 30, 2019 December 31, 2018 (unaudited) Accrued personnel expenses $ 1,679 $ 2,649 Accrued clinical and development expenses 3,645 3,349 Other 395 256 Total $ 5,719 $ 6,254

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2019
Commitments And Contingencies Disclosure [Abstract]
Schedule of Maturities of Lease Liability	As of September 30, 2019, maturities of lease liability due under the Company’s lease are as follows (in thousands): 2019 (remaining) $ 179 2020 732 Present value adjustment (48 ) Present value of lease payments $ 863 Lease liability $ 741 Long term lease liability 122 Present value of lease payments $ 863

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Share-based Compensation, Allocation of Recognized Period Costs	Total stock-based compensation expense for employees and non-employees recognized in the statements of operations was as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 (unaudited) (unaudited) Research and development $ 636 $ 475 $ 1,660 $ 1,217 General and administrative 837 519 1,900 1,347 Total stock-based compensation expense $ 1,473 $ 994 $ 3,560 $ 2,564
Schedule of Stock Option Activity	The table below summarizes stock option activity under the 2011 Plan and 2018 Plan: Number of Shares Outstanding Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (Years) Aggregate Intrinsic Value (in thousands) Balances at December 31, 2018 3,905,470 $ 5.35 8.65 $ 2,509 Forfeited/expired (197,689 ) 9.38 Exercised (60,347 ) 2.54 254 Granted 520,850 5.97 Balances at September 30, 2019 4,168,284 $ 5.27 8.06 $ 2,816

Formation and Business of the_2

Formation and Business of the Company (Details) - USD ($)	Feb. 01, 2019	Jan. 31, 2018	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Schedule Of Capitalization Equity [Line Items]
Maximum aggregate offering price of securities	$ 150,000,000
Net loss			$ (16,855,000)	$ (16,477,000)	$ (18,873,000)	$ (12,847,000)	$ (8,347,000)	$ (12,657,000)	$ (52,205,000)	$ (33,852,000)
Net cash used in operating activities									(48,687,000)	$ (36,116,000)
Cash, cash equivalents and investments			93,400,000						93,400,000
Accumulated deficit			$ (162,841,000)						$ (162,841,000)		$ (110,636,000)
Convertible Stock Converted into Shares of Common Stock
Schedule Of Capitalization Equity [Line Items]
Common shares issued upon conversion of convertible stock (shares)		9,629,405
Cantor Fitzgerald & Co
Schedule Of Capitalization Equity [Line Items]
Service fee as percentage of gross proceeds on sale of shares	3.00%
IPO
Schedule Of Capitalization Equity [Line Items]
Shares issued (shares)		8,050,000
Proceeds from issuance initial public offering, net		$ 125,400,000
Underwriter’s Option
Schedule Of Capitalization Equity [Line Items]
Shares issued (shares)		1,050,000
Common Stock
Schedule Of Capitalization Equity [Line Items]
Shares issued (shares)									613,522
Net proceeds from sale of securities after commission and before offering costs									$ 4,800,000
Proceeds from sale of securities, commission									100,000
Proceeds from sale of securities, offering costs									$ 200,000
Common Stock | At-The-Market Offering Under Sales Agreement | Cantor Fitzgerald & Co
Schedule Of Capitalization Equity [Line Items]
Maximum aggregate offering price of securities	$ 50,000,000

Significant Accounting Polici_4

Significant Accounting Policies - Segments (Details)	9 Months Ended
	Sep. 30, 2019Segment
Accounting Policies [Abstract]
Number of operating segments	1

Significant Accounting Polici_5

Significant Accounting Policies - Revenue Recognition (Details)	9 Months Ended
	Sep. 30, 2019USD ($)
Accounting Policies [Abstract]
Revenues recognized refundable	$ 0

Significant Accounting Polici_6

Significant Accounting Policies - Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accounting Policies [Abstract]
Net loss attributable to common stockholders, basic	$ (16,855)	$ (12,847)	$ (52,205)	$ (33,852)
Weighted-average common shares outstanding	23,961,823	23,063,757	23,734,573	21,269,957
Less: weighted-average common shares subject to repurchase	(6,613)	(85,964)	(26,450)	(105,888)
Weighted-average common shares used to compute basic and diluted net loss per share	23,955,210	22,977,793	23,708,123	21,164,069
Net loss attributable to common stockholders per share, basic and diluted	$ (0.70)	$ (0.56)	$ (2.20)	$ (1.60)

Significant Accounting Polici_7

Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings 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 excluded from the calculation of EPS	6,552,524	5,385,054
Stock options available for issuance
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the calculation of EPS	937,566	2,195,901
Stock options outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the calculation of EPS	4,168,284	3,050,067
Restricted stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the calculation of EPS	966,040
Outstanding common stock subject to repurchase
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the calculation of EPS		79,351
Shares issuable related to ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the calculation of EPS	480,634	59,735

Significant Accounting Polici_8

Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Lease liabilities	$ 741
Right-of-use assets	$ 830
Accounting Standards Update (“ASU”) 2016-02
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Lease liabilities		$ 800
Right-of-use assets		$ 800

Cash Equivalents and Investme_3

Cash Equivalents and Investments (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)investment	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)investment	Sep. 30, 2018USD ($)
Investments Debt And Equity Securities [Abstract]
Realized gains (losses) recognized on the sale or maturity of available-for-sale securities | $	$ 0	$ 0	$ 0	$ 0
Securities in continuous unrealized loss position for more than one year | investment	0		0

Cash Equivalents and Investme_4

Cash Equivalents and Investments - Cash and Available-for-Sale securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	$ 93,325	$ 136,346
Available-for-sale securities, unrealized gains	39	2
Available-for-sale securities, unrealized losses	(4)	(98)
Available-for-sale securities, fair value	93,360	136,250
Cash and cash equivalents	34,244	49,510
Short-term investments	57,112	86,740
Long-term investments	2,004
Total	93,360	136,250
Cash and money market funds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	16,075	7,490
Available-for-sale securities, unrealized gains	0	0
Available-for-sale securities, unrealized losses	0	0
Available-for-sale securities, fair value	16,075	7,490
Corporate notes
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	30,610	41,103
Available-for-sale securities, unrealized gains	35	2
Available-for-sale securities, unrealized losses	0	(70)
Available-for-sale securities, fair value	30,645	41,035
Agency bonds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	2,000
Available-for-sale securities, unrealized gains	0
Available-for-sale securities, unrealized losses	(1)
Available-for-sale securities, fair value	1,999
Asset backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	1,199	12,236
Available-for-sale securities, unrealized gains	1	0
Available-for-sale securities, unrealized losses	0	(23)
Available-for-sale securities, fair value	1,200	12,213
Government notes
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	11,003	12,481
Available-for-sale securities, unrealized gains	3	0
Available-for-sale securities, unrealized losses	(1)	(5)
Available-for-sale securities, fair value	11,005	12,476
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	32,438	63,036
Available-for-sale securities, unrealized gains	0	0
Available-for-sale securities, unrealized losses	(2)	0
Available-for-sale securities, fair value	$ 32,436	$ 63,036

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	$ 90,057	$ 134,562
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market funds	$ 12,772	5,802
Net asset value	$ 1
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	$ 32,436	63,036
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	12,772	5,802
Level 1 | Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market funds	12,772	5,802
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	77,285	128,760
Level 2 | Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	32,436	63,036
Corporate notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	30,645	41,035
Corporate notes | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	30,645	41,035
Agency bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,999
Agency bonds | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,999
Asset backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,200	12,213
Asset backed securities | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	1,200	12,213
Government notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	11,005	12,476
Government notes | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	$ 11,005	$ 12,476

License Agreements (Details)

License Agreements (Details)	1 Months Ended			3 Months Ended		9 Months Ended
	May 31, 2018USD ($)	Aug. 31, 2016USD ($)Milestone	Dec. 31, 2012USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Sep. 30, 2018USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Number of milestones | Milestone		2
Merck
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative agreement, milestone payments paid	$ 3,000,000
Merck | License
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Licensing fee			$ 1,000,000
Merck | Development and Regulatory Milestones
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangements, potential milestone payments			$ 25,000,000
JT Torii
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accelerated recognition of deferred revenue, amount of revenue recognized					$ 8,100,000
Research and development arrangement, contract to perform for others, compensation earned					$ 2,000,000
JT Torii | Research and Development Arrangement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development arrangement, contract to perform for others, compensation earned				$ 0		$ 10,600,000
JT Torii | Development and Regulatory Milestones
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangements, potential milestone proceeds		$ 28,000,000
JT Torii | Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative agreement, upfront payment received		11,000,000
JT Torii | Commercial Milestone
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangements, potential milestone proceeds		15,000,000
JT Torii | Development and Regulatory Milestone, Preparation of Investigational New Drug Submission, Milestone One [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangements, potential milestone proceeds		$ 2,000,000

Balance Sheets Components (Deta

Balance Sheets Components (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accrued personnel expenses	$ 1,679	$ 2,649
Accrued clinical and development expenses	3,645	3,349
Other	395	256
Total	$ 5,719	$ 6,254

Commitments and Contingencies_2

Commitments and Contingencies (Details)	Apr. 12, 2019USD ($)	Oct. 01, 2017USD ($)ft²	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)
Acquired Indefinite Lived Intangible Assets [Line Items]
Operating lease, monthly expense	$ 60,000
Operating lease, discount rate, percent			8.41%		8.41%
Operating lease, right-of-use asset, amortization			$ 200,000		$ 484,000
Operating lease, Remaining lease term	1 year 8 months 12 days		1 year 3 months 18 days		1 year 3 months 18 days
Operating lease amendment date	Apr. 12, 2019
Operating lease extended term	9 months
Operating lease, option to extend	true
Operating lease option to extend, description	The lease was extended for an additional nine months, from March 31, 2020 to December 31, 2020
Operating lease, rent expense			$ 200,000	$ 200,000	$ 500,000	$ 600,000
Redwood City, California
Acquired Indefinite Lived Intangible Assets [Line Items]
Operating lease, term of contract		30 months
Leased office space, square footage | ft²		14,000
Operating lease, monthly expense		$ 55,000

Commitments and Contingencies -

Commitments and Contingencies - Schedule of Maturities of Lease Liability (Details) $ in Thousands	Sep. 30, 2019USD ($)
Maturities of lease liability
2019 (remaining)	$ 179
2020	732
Present value adjustment	(48)
Present value of lease payments	863
Lease liability	741
Long term lease liability	122
Present value of lease payments	$ 863

Stockholders' Equity (Details)

Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense			$ 1,473	$ 994	$ 3,560	$ 2,564
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense			636	475	1,660	1,217
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense			$ 837	$ 519	$ 1,900	$ 1,347
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			966,040		966,040
Weighted-average award fair value			$ 4.08		$ 4.08
2011 Stock Incentive Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option vesting period					4 years
2011 Stock Incentive Plan | Maximum | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option expiration period					10 years
2018 Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share reserve increased by number of shares	929,327
Shares available for issuance under the Plan (shares)			937,566		937,566
2018 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share reserve increased by number of shares	232,332
Purchase of common stock offer period under the plan		6 months
Discount rate from price of common stock on purchase date		15.00%
Commencement date to purchase common stock under the ESPP		Sep. 1, 2018
Shares available under the Plan (shares)			480,634		480,634

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019USD ($)$ / sharesshares	Dec. 31, 2018USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Balances, beginning (shares) | shares	3,905,470
Forfeited/expired (shares) | shares	(197,689)
Exercised (shares) | shares	(60,347)
Granted (shares) | shares	520,850
Balances, ending (shares) | shares	4,168,284	3,905,470
Outstanding, exercise price per share (in USD per share) | $ / shares	$ 5.35
Forfeited/expired, exercise price per share (in USD per share) | $ / shares	9.38
Exercised, exercise price per share (in USD per share) | $ / shares	2.54
Granted, exercise price per share (in USD per share) | $ / shares	5.97
Outstanding, exercise price per share (in USD per share) | $ / shares	$ 5.27	$ 5.35
Options outstanding, weighted average remaining contractual term	8 years 21 days	8 years 7 months 24 days
Options outstanding, aggregate intrinsic value | $	$ 2,816	$ 2,509
Exercised, aggregate intrinsic value | $	$ 254