VYNE Therapeutics (VYNE) 10-Q 7 Nov 18 2018 Q3 Quarterly report Financial data

DEI Document

DEI Document - shares	9 Months Ended
	Sep. 30, 2018	Nov. 01, 2018
Entity [Abstract]
Entity Registrant Name	Menlo Therapeutics Inc.
Entity Central Index Key	1,566,044
Trading Symbol	MNLO
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding		23,232,184

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 70,196	$ 10,206
Short-term investments	82,461	49,295
Accounts receivable		786
Prepaid expenses and other current assets	1,811	3,574
Total current assets	154,468	63,861
Long-term investments		2,978
Property and equipment, net	136	28
Other long-term assets	354
Total assets	154,958	66,867
Current liabilities:
Accounts payable	2,702	2,462
Accrued expenses and other current liabilities	5,360	3,559
Deferred revenue, current		1,796
Total current liabilities	8,062	7,817
Deferred revenue, long-term		6,735
Other non-current liabilities	12	22
Total liabilities	8,074	14,574
Commitments and contingencies (see Note 7)
Stockholders’ equity (deficit):
Preferred stock: $0.0001 par value; 20,000,000 shares and no shares authorized at September 30, 2018 and December 2017, respectively; no shares issued and outstanding at September 30, 2018 and December 31, 2017	0	0
Common stock: $0.0001 par value; 300,000,000 shares and 55,000,000 shares authorized at September 30, 2018 and December 31, 2017, respectively; 23,232,184 and 5,298,593 shares issued and outstanding at September 30, 2018 and December 31, 2017, respectively	3	1
Additional paid-in capital	240,024	2,207
Accumulated other comprehensive loss	(101)	(51)
Accumulated deficit	(93,042)	(59,191)
Total stockholders’ equity (deficit)	146,884	(57,034)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	154,958	66,867
Series A Convertible Preferred Stock
Current liabilities:
Convertible preferred stock	0	14,183
Series B Convertible Preferred Stock
Current liabilities:
Convertible preferred stock	0	44,820
Series C Convertible Preferred Stock
Current liabilities:
Convertible preferred stock	$ 0	$ 50,324

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Preferred stock, par value per share (in USD per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (shares)	20,000,000	0
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	55,000,000
Common stock issued (shares)	23,232,184	5,298,593
Common stock outstanding (shares)	23,232,184	5,298,593
Series A Convertible Preferred Stock
Convertible preferred stock, par value per share (in USD per share)	$ 0.001	$ 0.001
Convertible preferred stock authorized (shares)	0	14,300
Convertible preferred stock issued (shares)	0	14,300
Convertible preferred stock outstanding (shares)	0	14,300
Convertible preferred stock, liquidation value	$ 0	$ 14,300
Series B Convertible Preferred Stock
Convertible preferred stock, par value per share (in USD per share)	$ 0.001	$ 0.001
Convertible preferred stock authorized (shares)	0	14,106,583
Convertible preferred stock issued (shares)	0	14,106,583
Convertible preferred stock outstanding (shares)	0	14,106,583
Convertible preferred stock, liquidation value	$ 0	$ 45,000
Series C Convertible Preferred Stock
Convertible preferred stock, par value per share (in USD per share)	$ 0.001	$ 0.001
Convertible preferred stock authorized (shares)	0	14,201,878
Convertible preferred stock issued (shares)	0	11,854,463
Convertible preferred stock outstanding (shares)	0	11,854,463
Convertible preferred stock, liquidation value	$ 0	$ 50,500

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Collaboration and license revenue		$ 909	$ 10,640	$ 1,807
Type of Revenue [Extensible List]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development	$ 10,667	$ 8,008	$ 37,913	$ 18,461
General and administrative	3,035	1,236	8,822	3,462
Total operating expenses	13,702	9,244	46,735	21,923
Loss from operations	(13,702)	(8,335)	(36,095)	(20,116)
Interest income and other expense, net	855	163	2,243	316
Net loss attributable to common stockholders	(12,847)	(8,172)	(33,852)	(19,800)
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale securities	48	(19)	(50)	11
Comprehensive loss	$ (12,799)	$ (8,191)	$ (33,902)	$ (19,789)
Net loss attributable to common stockholders per share, basic and diluted	$ (0.56)	$ (1.60)	$ (1.60)	$ (3.89)
Weighted-average number of common shares used to compute basic and diluted net loss per share	22,977,793	5,116,165	21,164,069	5,093,418

Condensed Statement of Cash Flo

Condensed Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Net loss	$ (33,852)	$ (19,800)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	10	5
Amortization of premium on investment securities	(551)	73
Stock-based compensation expense	2,564	1,217
Disposal of equipment		19
Change in operating assets and liabilities:
Accounts receivable	786	(460)
Prepaid expenses and other current assets	1,763	(1,143)
Other long-term assets	(354)	66
Accounts payable	240	2,001
Accrued expenses and other current liabilities	1,819	1,320
Deferred revenue	(8,531)	(1,347)
Other non-current liabilities	(10)	(16)
Net cash used in operating activities	(36,116)	(18,065)
Investing activities
Purchase of property plant and equipment	(118)	(15)
Purchase of investments	(109,952)	(59,171)
Proceeds from sales of investments	5,100	6,000
Proceeds from maturities of investments	75,165	31,821
Net cash used in investing activities	(29,805)	(21,365)
Financing activities
Proceeds from issuance of common stock, net of issuance costs	125,417	50,327
Proceeds from the exercise of stock options	494	34
Net cash provided by financing activities	125,911	50,361
Net increase in cash and cash equivalents	59,990	10,931
Cash and cash equivalents at beginning of period	10,206	4,027
Cash and cash equivalents at end of period	70,196	$ 14,958
Non-cash financing activities
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, 2018
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, psoriasis and chronic pruritus of unknown origin. The Company believes that its product candidate, serlopitant, a highly selective once‑daily, oral small molecule inhibitor of the neurokinin 1, or NK 1 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. 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 reclassification 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, 2018, the Company incurred a net loss of $33.9 million and used Management expects to continue to incur additional substantial losses in the foreseeable future as a result of the Company’s research and development activities. 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, 2018 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 nine months ended September 30, 2018.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
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, 2018 and 2017 is unaudited. These unaudited interim condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. In management’s opinion, the unaudited interim condensed financial statements have been prepared on the same basis as the audited financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, and include all adjustments, which include only normal and recurring adjustments necessary for the fair presentation of the Company’s statement of financial position as of September 30, 2018, its statements of operations and comprehensive loss for the three and nine months ended September 30, 2018 and 2017 and its statements of cash flows for the nine months ended September 30, 2018 and 2017. The results for the three and nine months ended September 30, 2018 are not necessarily indicative of the results expected for the full fiscal year or any other period(s). The financial statements and related disclosures have been prepared with the presumption that users of the interim financial statements have read or have access to the audited financial statements for the preceding fiscal year. Accordingly, these financial statements should be read in conjunction with the audited financial statements and notes thereto contained in the Company’s Form 10-K for the year ended December 31, 2017, as filed with the SEC on March 28, 2018. Reverse Stock Split On January 8, 2018, the Company effected a reverse split of shares of the Company’s common stock at a ratio of 1-for-2.6975 pursuant to an amendment to the amended and restated certificate of incorporation approved by the Company’s board of directors and stockholders. The par value and the authorized shares of the common stock were not adjusted as a result of the reverse split. All issued and outstanding common stock share and per share amounts contained in the financial statements have been retroactively adjusted to reflect this reverse split for all periods presented, and the conversion ratio of the preferred stock was adjusted accordingly. 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. GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and 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 on 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 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. Stock-Based Compensation The Company measures and recognizes compensation expense for all stock‑based awards made to employees, directors and non‑employees, based on estimated fair values recognized using the straight‑line method over the requisite service period. The fair value of options to purchase common stock granted to 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. The Company accounts for options issued to non‑employees using the Black‑Scholes option valuation model and is measured and recognized as the stock options are earned. Revenue Recognition The Company records revenue based on a five-step model in accordance with Accounting Standards Codification ("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, 2018 and 2017, diluted net loss per common share is the same as basic net loss per common share for those periods. 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, 2018 2017 2018 2017 (unaudited) (unaudited) Numerator: Net loss attributable to common stockholders, basic and diluted $ (12,847 ) $ (8,172 ) $ (33,852 ) $ (19,800 ) Denominator: Weighted-average common shares outstanding 23,063,757 5,283,282 21,269,957 5,281,144 Less: weighted-average common shares subject to repurchase (85,964 ) (167,117 ) (105,888 ) (187,726 ) Weighted-average common shares used to compute basic and diluted net loss per share 22,977,793 5,116,165 21,164,069 5,093,418 Net loss per share attributable to common stockholders Basic and diluted $ (0.56 ) $ (1.60 ) $ (1.60 ) $ (3.89 ) 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, 2018 2017 (unaudited) Stock options outstanding 3,050,067 2,152,906 Outstanding common stock subject to repurchase 79,351 160,246 Shares issuable related to ESPP 59,735 — Convertible preferred stock issuable upon conversion to common stock — 9,629,405 Total 3,189,153 11,942,557 Recent Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014‑09, Revenue from Contracts with Customers (Topic 606) Revenue Recognition Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date In February 2016, the Financial Accounting Standards Board (“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 In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In June 2018, the FASB issued ASU 2018-07 Improvements to Nonemployee Share-Based Payment Accounting (Topic 718) In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820) In August 2018, the FASB issued ASU No. 2018-15, Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40)

Cash Equivalents and Investment

Cash Equivalents and Investments	9 Months Ended
	Sep. 30, 2018
Investments Debt And Equity Securities [Abstract]
Cash Equivalents and Investments	3. Cash Equivalents and Investments At September 30, 2018 and December 31, 2017, the balance in the Company’s accumulated other comprehensive income was comprised solely of activity related to the Company’s available‑for‑sale securities. There were no realized gains or losses recognized on the sale or maturity of available‑for‑sale securities during the three and nine months ended September 30, 2018 and 2017 and as a result, the Company did not reclassify any amounts out of accumulated other comprehensive income for the same periods. The following table summarizes the available‑for‑sale securities (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Fair Value September 30, 2018 (unaudited) Money market funds $ 9,850 $ — $ — $ 9,850 Corporate notes 31,749 — (55 ) 31,694 Commercial paper 83,744 — — 83,744 Asset backed securities 12,226 — (28 ) 12,198 Government notes 12,448 — (18 ) 12,430 Total $ 150,017 $ — $ (101 ) $ 149,916 Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2017: Money market funds $ 8,685 $ — $ — $ 8,685 Corporate notes 46,133 — (35 ) 46,098 Government notes 6,191 — (16 ) 6,175 Total $ 61,009 $ — $ (51 ) $ 60,958

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2018
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, 2018 (unaudited) Assets: Money market funds $ 9,850 $ — $ — $ 9,850 Corporate notes — 31,694 — 31,694 Commercial paper — 83,744 — 83,744 Asset backed securities — 12,198 — 12,198 Government notes — 12,430 — 12,430 Total assets $ 9,850 $ 140,066 — $ 149,916 Fair Value Measurements Using Level 1 Level 2 Level 3 Total December 31, 2017: Assets: Money market funds $ 8,685 $ — $ — $ 8,685 Corporate notes 5,103 40,995 — 46,098 Government notes 6,175 — — 6,175 Total assets $ 19,963 $ 40,995 $ — $ 60,958 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, 2018
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 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, 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. 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, the Company recognized revenue of zero and $10.6 million, respectively in the statement of operations related to the services and collaboration agreement. The services agreement terminated upon the termination of the Collaboration Agreement.

Balance Sheets Components

Balance Sheets Components	9 Months Ended
	Sep. 30, 2018
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, 2018 December 31, 2017 (unaudited) Accrued personnel expenses $ 1,805 $ 1,108 Accrued clinical and development expenses 3,215 2,250 Other 340 201 Total $ 5,360 $ 3,559

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Legal Matters The Company’s industry is characterized by frequent claims and litigation, including claims regarding intellectual property. As a result, the Company may be subject to various legal proceedings from time to time. The results of any future litigation cannot be predicted with certainty, and regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources and other factors. Management is not aware of any material pending or threatened litigation. Leases The Company conducts its operations using leased office facilities. In April 2016, the Company entered into a lease agreement for its prior location. The twenty-six month lease, began in May 2016, and provided 4,000 square feet of office space in Menlo Park, California. Base annual rent was initially approximately $20,000 per month, with annual increases. 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 is approximately $55,000 per month with annual increases. The Company recognizes rent expense on a straight‑line basis over the respective lease period. Rent expense was $0.2 million and $0.6 million, respectively, for the three and nine months ended September 30, 2018 and $0.1 million and $0.2 million, respectively, for the three and nine months ended September 30, 2017. 2018 $ 168 2019 674 2020 173 Total future minimum lease payments $ 1,015 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, 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 (Deficit)

Stockholders' Equity (Deficit)	9 Months Ended
	Sep. 30, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stockholders' Equity (Deficit)	8. Stockholders’ Equity (Deficit) Equity incentive plan 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. 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). The Company has reserved 3,000,000 shares of common stock for issuance pursuant to awards under the 2018 Plan. As of September 30, 2018, the Company has 2,195,901 shares of common stock available for issuance under the 2018 Plan. 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. The Company has reserved 325,000 shares of common stock for issuance under the ESPP. 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, 2018 2017 2018 2017 (unaudited) (unaudited) Research and development $ 475 $ 322 $ 1,217 $ 676 General and administrative 519 267 1,347 541 Total stock-based compensation expense $ 994 $ 589 $ 2,564 $ 1,217 The table below summarizes stock option and restricted award activity under the 2011 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, 2017 2,506,926 $ 3.50 8.79 $ 24,033 Forfeited (6,772 ) $ 7.01 Exercised (254,186 ) $ 1.94 1,786 Granted 804,099 $ 9.87 Balances at September 30, 2018 3,050,067 $ 5.31 8.53 $ 14,880

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial information for the three and nine months ended September 30, 2018 and 2017 is unaudited. These unaudited interim condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Certain information and note disclosures normally included in the financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. In management’s opinion, the unaudited interim condensed financial statements have been prepared on the same basis as the audited financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017, and include all adjustments, which include only normal and recurring adjustments necessary for the fair presentation of the Company’s statement of financial position as of September 30, 2018, its statements of operations and comprehensive loss for the three and nine months ended September 30, 2018 and 2017 and its statements of cash flows for the nine months ended September 30, 2018 and 2017. The results for the three and nine months ended September 30, 2018 are not necessarily indicative of the results expected for the full fiscal year or any other period(s). The financial statements and related disclosures have been prepared with the presumption that users of the interim financial statements have read or have access to the audited financial statements for the preceding fiscal year. Accordingly, these financial statements should be read in conjunction with the audited financial statements and notes thereto contained in the Company’s Form 10-K for the year ended December 31, 2017, as filed with the SEC on March 28, 2018.
Reverse Stock Split	Reverse Stock Split On January 8, 2018, the Company effected a reverse split of shares of the Company’s common stock at a ratio of 1-for-2.6975 pursuant to an amendment to the amended and restated certificate of incorporation approved by the Company’s board of directors and stockholders. The par value and the authorized shares of the common stock were not adjusted as a result of the reverse split. All issued and outstanding common stock share and per share amounts contained in the financial statements have been retroactively adjusted to reflect this reverse split for all periods presented, and the conversion ratio of the preferred stock was adjusted accordingly. 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. GAAP, requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and 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 on 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 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.
Stock-Based Compensation	Stock-Based Compensation The Company measures and recognizes compensation expense for all stock‑based awards made to employees, directors and non‑employees, based on estimated fair values recognized using the straight‑line method over the requisite service period. The fair value of options to purchase common stock granted to 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. The Company accounts for options issued to non‑employees using the Black‑Scholes option valuation model and is measured and recognized as the stock options are earned.
Revenue Recognition	Revenue Recognition The Company records revenue based on a five-step model in accordance with Accounting Standards Codification ("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, 2018 and 2017, 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 In May 2014, the FASB issued ASU No. 2014‑09, Revenue from Contracts with Customers (Topic 606) Revenue Recognition Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date In February 2016, the Financial Accounting Standards Board (“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 In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In June 2018, the FASB issued ASU 2018-07 Improvements to Nonemployee Share-Based Payment Accounting (Topic 718) In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820) In August 2018, the FASB issued ASU No. 2018-15, Intangibles – Goodwill and Other – Internal-Use Software (Subtopic 350-40)

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2018
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, 2018 2017 2018 2017 (unaudited) (unaudited) Numerator: Net loss attributable to common stockholders, basic and diluted $ (12,847 ) $ (8,172 ) $ (33,852 ) $ (19,800 ) Denominator: Weighted-average common shares outstanding 23,063,757 5,283,282 21,269,957 5,281,144 Less: weighted-average common shares subject to repurchase (85,964 ) (167,117 ) (105,888 ) (187,726 ) Weighted-average common shares used to compute basic and diluted net loss per share 22,977,793 5,116,165 21,164,069 5,093,418 Net loss per share attributable to common stockholders Basic and diluted $ (0.56 ) $ (1.60 ) $ (1.60 ) $ (3.89 )
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, 2018 2017 (unaudited) Stock options outstanding 3,050,067 2,152,906 Outstanding common stock subject to repurchase 79,351 160,246 Shares issuable related to ESPP 59,735 — Convertible preferred stock issuable upon conversion to common stock — 9,629,405 Total 3,189,153 11,942,557

Cash Equivalents and Investme_2

Cash Equivalents and Investments (Tables)	9 Months Ended
	Sep. 30, 2018
Investments Debt And Equity Securities [Abstract]
Summary of Available-for-sale Securities	The following table summarizes the available‑for‑sale securities (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Fair Value September 30, 2018 (unaudited) Money market funds $ 9,850 $ — $ — $ 9,850 Corporate notes 31,749 — (55 ) 31,694 Commercial paper 83,744 — — 83,744 Asset backed securities 12,226 — (28 ) 12,198 Government notes 12,448 — (18 ) 12,430 Total $ 150,017 $ — $ (101 ) $ 149,916 Amortized Cost Unrealized Gains Unrealized Losses Fair Value December 31, 2017: Money market funds $ 8,685 $ — $ — $ 8,685 Corporate notes 46,133 — (35 ) 46,098 Government notes 6,191 — (16 ) 6,175 Total $ 61,009 $ — $ (51 ) $ 60,958

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2018
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, 2018 (unaudited) Assets: Money market funds $ 9,850 $ — $ — $ 9,850 Corporate notes — 31,694 — 31,694 Commercial paper — 83,744 — 83,744 Asset backed securities — 12,198 — 12,198 Government notes — 12,430 — 12,430 Total assets $ 9,850 $ 140,066 — $ 149,916 Fair Value Measurements Using Level 1 Level 2 Level 3 Total December 31, 2017: Assets: Money market funds $ 8,685 $ — $ — $ 8,685 Corporate notes 5,103 40,995 — 46,098 Government notes 6,175 — — 6,175 Total assets $ 19,963 $ 40,995 $ — $ 60,958

Balance Sheets Components (Tabl

Balance Sheets Components (Tables)	9 Months Ended
	Sep. 30, 2018
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, 2018 December 31, 2017 (unaudited) Accrued personnel expenses $ 1,805 $ 1,108 Accrued clinical and development expenses 3,215 2,250 Other 340 201 Total $ 5,360 $ 3,559

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2018
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Operating Lease Payments	As of September 30, 2018, total future minimum lease payments under its operating leases are as follows (in thousands): 2018 $ 168 2019 674 2020 173 Total future minimum lease payments $ 1,015

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) (Tables)	9 Months Ended
	Sep. 30, 2018
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, 2018 2017 2018 2017 (unaudited) (unaudited) Research and development $ 475 $ 322 $ 1,217 $ 676 General and administrative 519 267 1,347 541 Total stock-based compensation expense $ 994 $ 589 $ 2,564 $ 1,217
Schedule of Stock Option and Restricted Stock Activity	The table below summarizes stock option and restricted award activity under the 2011 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, 2017 2,506,926 $ 3.50 8.79 $ 24,033 Forfeited (6,772 ) $ 7.01 Exercised (254,186 ) $ 1.94 1,786 Granted 804,099 $ 9.87 Balances at September 30, 2018 3,050,067 $ 5.31 8.53 $ 14,880

Formation and Business of the_2

Formation and Business of the Company (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Schedule of Capitalization, Equity [Line Items]
Net loss		$ (12,847)	$ (8,172)	$ (33,852)	$ (19,800)
Net cash used in operating activities				(36,116)	$ (18,065)
Cash, cash equivalents and investments		152,700		152,700
Accumulated deficit		$ (93,042)		$ (93,042)		$ (59,191)
IPO
Schedule of Capitalization, Equity [Line Items]
Shares issued (shares)	8,050,000
Proceeds from issuance initial public offering, net	$ 125,400
Over-Allotment Option
Schedule of Capitalization, Equity [Line Items]
Shares issued (shares)	1,050,000
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

Significant Accounting Polici_4

Significant Accounting Policies - Reverse Stock Split (Details)	Jan. 08, 2018
Common Stock
Class of Stock [Line Items]
Number of shares issued for every share converted in reverse stock split	0.3707

Significant Accounting Polici_5

Significant Accounting Policies - Segments (Details)	9 Months Ended
	Sep. 30, 2018Segment
Accounting Policies [Abstract]
Number of operating segments	1

Significant Accounting Polici_6

Significant Accounting Policies - Revenue Recognition (Details)	9 Months Ended
	Sep. 30, 2018USD ($)
Accounting Policies [Abstract]
Revenues recognized refundable	$ 0

Significant Accounting Polici_7

Significant Accounting Policies - Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accounting Policies [Abstract]
Net loss attributable to common stockholders, basic	$ (12,847)	$ (8,172)	$ (33,852)	$ (19,800)
Weighted-average common shares outstanding	23,063,757	5,283,282	21,269,957	5,281,144
Less: weighted-average common shares subject to repurchase	(85,964)	(167,117)	(105,888)	(187,726)
Weighted-average common shares used to compute basic and diluted net loss per share	22,977,793	5,116,165	21,164,069	5,093,418
Net loss attributable to common stockholders per share, basic and diluted	$ (0.56)	$ (1.60)	$ (1.60)	$ (3.89)

Significant Accounting Polici_8

Significant Accounting Policies - Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share (Details) - shares	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the calculation of EPS	3,189,153	11,942,557
Stock options outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the calculation of EPS	3,050,067	2,152,906
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	160,246
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	59,735
Convertible preferred stock issuable upon conversion to common stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the calculation of EPS	0	9,629,405

Cash Equivalents and Investme_3

Cash Equivalents and Investments (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)investment	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)investment	Sep. 30, 2017USD ($)
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 - Available for Sale securities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	$ 150,017	$ 61,009
Available-for-sale securities, unrealized gains	0	0
Available-for-sale securities, unrealized losses	(101)	(51)
Available-for-sale securities, fair value	149,916	60,958
Corporate notes
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	31,749	46,133
Available-for-sale securities, unrealized gains	0	0
Available-for-sale securities, unrealized losses	(55)	(35)
Available-for-sale securities, fair value	31,694	46,098
Government notes
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	12,448	6,191
Available-for-sale securities, unrealized gains	0	0
Available-for-sale securities, unrealized losses	(18)	(16)
Available-for-sale securities, fair value	12,430	6,175
Asset backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	12,226
Available-for-sale securities, unrealized gains	0
Available-for-sale securities, unrealized losses	(28)
Available-for-sale securities, fair value	12,198
Money market funds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	9,850	8,685
Available-for-sale securities, unrealized gains	0	0
Available-for-sale securities, unrealized losses	0	0
Available-for-sale securities, fair value	9,850	$ 8,685
Commercial paper
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	83,744
Available-for-sale securities, unrealized gains	0
Available-for-sale securities, unrealized losses	0
Available-for-sale securities, fair value	$ 83,744

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ / shares in Units, $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	$ 149,916	$ 60,958
Corporate notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	31,694	46,098
Asset backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	12,198
Government notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	12,430	6,175
Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	9,850	19,963
Level 1 | Corporate notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		5,103
Level 1 | Government notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments		6,175
Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	140,066	40,995
Level 2 | Corporate notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	31,694	40,995
Level 2 | Asset backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	12,198
Level 2 | Government notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	12,430
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market funds	$ 9,850	8,685
Net asset value	$ 1
Money market funds | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market funds	$ 9,850	$ 8,685
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	83,744
Commercial paper | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	$ 83,744

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, 2018	Dec. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accrued personnel expenses	$ 1,805	$ 1,108
Accrued clinical and development expenses	3,215	2,250
Other	340	201
Total	$ 5,360	$ 3,559

Commitments and Contingencies_2

Commitments and Contingencies (Details) $ in Thousands	Oct. 01, 2017USD ($)ft²	May 31, 2016USD ($)ft²	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)
Acquired Indefinite-lived Intangible Assets [Line Items]
Operating lease, rent expense			$ 200	$ 100	$ 600	$ 200
Menlo Park, California
Acquired Indefinite-lived Intangible Assets [Line Items]
Operating lease, term of contract		26 months
Leased office space, square footage | ft²		4,000
Operating lease, monthly expense		$ 20,000
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 - Future Minimum Operating Lease Payments (Details) $ in Thousands	Sep. 30, 2018USD ($)
Year ending December 31:
2,018	$ 168
2,019	674
2,020	173
Total future minimum lease payments	$ 1,015

Stockholders' Equity (Deficit_2

Stockholders' Equity (Deficit) (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 23, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense		$ 994	$ 589	$ 2,564	$ 1,217
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense		475	322	1,217	676
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense		$ 519	$ 267	$ 1,347	$ 541
2011 Stock Incentive Plan | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option expiration period				10 years
Option vesting period				4 years
2018 Omnibus Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available under the Plan (shares)						3,000,000
Shares available for issuance under the Plan (shares)		2,195,901		2,195,901
2018 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available under the Plan (shares)	325,000
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

Stockholders' Equity (Deficit_3

Stockholders' Equity (Deficit) - Stock Option and Restricted Stock Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Balances, beginning (shares)	2,506,926
Forfeited (shares)	(6,772)
Exercised (shares)	(254,186)
Granted (shares)	804,099
Balances, ending (shares)	3,050,067	2,506,926
Outstanding, exercise price per share (in USD per share)	$ 5.31	$ 3.50
Forfeited, exercise price per share (in USD per share)	7.01
Exercised, exercise price per share (in USD per share)	1.94
Granted, exercise price per share (in USD per share)	$ 9.87
Options outstanding, weighted average remaining contractual term	8 years 6 months 10 days	8 years 9 months 14 days
Options outstanding, aggregate intrinsic value	$ 24,033
Exercised, aggregate intrinsic value	1,786
Options outstanding, aggregate intrinsic value	$ 14,880	$ 24,033