VYNE Therapeutics (VYNE) 10-Q 9 May 18 2018 Q1 Quarterly report Financial data

DEI Document

DEI Document - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Entity [Abstract]
Entity Registrant Name	Menlo Therapeutics Inc.
Entity Central Index Key	1,566,044
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding		22,977,998
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 78,527	$ 10,206
Short‑term investments	77,310	49,295
Accounts receivable	234	786
Prepaid expenses and other current assets	3,587	3,574
Total current assets	159,658	63,861
Long‑term investments	20,713	2,978
Property and equipment, net	25	28
Other long‑term assets	83	0
Total assets	180,479	66,867
Current liabilities:
Accounts payable	3,501	2,462
Accrued expenses and other current liabilities	3,174	3,559
Deferred revenue, current	1,796	1,796
Total current liabilities	8,471	7,817
Deferred revenue, long‑term	6,286	6,735
Other non‑current liabilities	20	22
Total liabilities	14,777	14,574
Commitments and contingencies (see Note 7)
Stockholders’ deficit:
Preferred stock: $0.0001 par value; 20,000,000 shares and no shares authorized at March 31, 2018 and December 2017, respectively; no shares issued and outstanding at March 31, 2018 and December 31, 2017	0	0
Common stock: $0.0001 par value; 300,000,000 shares and 55,000,000 shares authorized at March 31, 2018 and December 31, 2017, respectively; 22,977,998 and 5,298,593 shares issued and outstanding at March 31, 2018 and December 31, 2017, respectively	3	1
Additional paid‑in capital	237,749	2,207
Accumulated other comprehensive loss	(202)	(51)
Accumulated deficit	(71,848)	(59,191)
Total stockholders’ deficit	165,702	(57,034)
Total liabilities, convertible preferred stock and stockholders’ deficit	180,479	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	Mar. 31, 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)	22,977,998	5,298,593
Common stock outstanding (shares)	22,977,998	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
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Collaboration and license revenue	$ 497	$ 449
Operating expenses:
Research and development	11,020	4,992
General and administrative	2,697	1,012
Total operating expenses	13,717	6,004
Loss from operations	(13,220)	(5,555)
Interest income and other expense, net	563	81
Net loss attributable to common stockholders	(12,657)	(5,474)
Other comprehensive loss:
Unrealized loss on available‑for‑sale securities	(151)	(4)
Comprehensive loss	$ (12,808)	$ (5,478)
Net loss attributable to common stockholders per share, basic and diluted (in USD per share)	$ (0.72)	$ (1.08)
Weighted‑average number of common shares used to compute basic and diluted net loss per share (in shares)	17,583,377	5,071,721

Condensed Statement of Cash Flo

Condensed Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net loss	$ (12,657)	$ (5,474)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	5	2
Amortization of premium on investment securities	(123)	47
Stock‑based compensation expense	822	316
Accrued interest	(88)	125
Change in operating assets and liabilities:
Accounts receivable	552	0
Prepaid expenses and other current assets	75	(179)
Other long‑term assets	(85)	66
Accounts payable	1,039	(303)
Accrued expenses and other current liabilities	(385)	278
Deferred revenue	(449)	(449)
Other non‑current liabilities	4	(13)
Net cash used in operating activities	(11,290)	(5,584)
Investing activities
Purchase of investments	(72,778)	(8,228)
Proceeds from sales of investments	4,100	1,200
Proceeds from maturities of investments	22,900	14,615
Net cash used in investing activities	(45,778)	7,587
Financing activities
Proceeds from issuance of common stock, net of issuance costs	125,389	0
Net cash provided by financing activities	125,389	0
Net increase in cash and cash equivalents	68,321	2,003
Cash and cash equivalents at beginning of period	10,206	4,026
Cash and cash equivalents at end of period	78,527	6,029
Non-cash financing activities
Conversion of preferred stock to common stock	$ 109,327	$ 0

Formation and Business of the C

Formation and Business of the Company	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Formation and Business of the Company	Formation and Business of the Company Menlo Therapeutics Inc., or 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 dermatologic conditions such as psoriasis and prurigo nodularis, as well as for the treatment of refractory chronic cough, a cough that persists for at least eight weeks despite treatment of any identified underlying cause. The Company believes that its product candidate, serlopitant, a highly selective once‑daily, oral small molecule inhibitor of the neurokinin 1 , or NK 1 receptor, has the potential to significantly alleviate itch and cough symptoms. Pruritus associated with psoriasis and prurigo nodularis, as well as refractory chronic cough, each represents a significant patient need. 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 over-allotment option granted to its underwriters, 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 three months ended March 31, 2018 , the Company incurred a net loss of $12.7 million and used $ 11.3 million of cash in operations. As of March 31, 2018 , the Company had cash, cash equivalents and investments of $176.6 million and an accumulated deficit of $71.8 million . 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 financing arrangements, and/or third‑party collaboration funding. 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 March 31, 2018 will provide sufficient funds to enable it to meet its obligations for at least the next twelve months.

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Basis of Presentation The accompanying financial information for the three months ended March 31, 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 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 our statement of financial position as of March 31, 2018 , our statements of operations and comprehensive loss for the three months ended March 31, 2018 and 2017 and our statements of cash flows for the three months ended March 31, 2018 and 2017. The results for the three months ended March 31, 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. 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 our 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. Under its collaboration agreement, the Company may receive milestone payments related to development and commercial achievements. 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, adjust the Company’s 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 does 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 months ended March 31, 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 March 31, 2018 2017 (unaudited) Numerator: Net loss attributable to common stockholders, basic and diluted $ (12,657 ) $ (5,474 ) Denominator: Weighted-average common shares outstanding 17,709,274 5,280,058 Less: weighted-average common shares subject to repurchase (125,897 ) (208,337 ) Weighted-average common shares used to compute basic and diluted net loss per share 17,583,377 5,071,721 Net loss per share attributable to common stockholders Basic and diluted $ (0.72 ) $ (1.08 ) 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: March 31, 2018 2017 (unaudited) Stock options available for issuance 3,731,172 1,123,911 Stock options outstanding 2,505,754 1,595,499 Outstanding common stock subject to repurchase 119,026 201,466 Convertible preferred stock issuable upon conversion to common stock — 5,234,800 Total 6,355,952 8,155,676 Recent Accounting Pronouncements In February 2016, the FASB issued ASU 2016‑02, Leases (ASC 842), which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight‑line basis over the term of the lease, respectively. A lessee is also required to record a right‑of‑use asset and a lease liability for all leases with a term of greater than twelve months regardless of their classification. Leases with a term of twelve months or less will be accounted for similar to existing guidance for operating leases today. ASC 842 supersedes the previous leases standard, ASC 840 Leases . The standard is effective on January 1, 2019, with early adoption permitted. The Company is currently evaluating the effects, if any, that the adoption of this guidance will have on its financial statements. In May 2014, the FASB issued ASU No. 2014‑09, Revenue from Contracts with Customers (Topic 606) , which supersedes the revenue recognition requirements in ASC 605, Revenue Recognition . This ASU is based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. In August 2015, FASB issued ASU No. 2015‑14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date , which effectively delayed the adoption date by one year, to an effective date for public entities for annual and interim periods beginning after December 15, 2017. In March, April and May 2016, the FASB issued additional updates to the new revenue standard relating to reporting revenue on a gross versus net basis, identifying performance obligations and licensing arrangements, and narrow‑scope improvements and practical expedients, respectively. The effective date of this additional update is the same as that of ASU 2014‑09. The guidance permits the use of either a full retrospective or modified retrospective method. The Company adopted the standard using the full retrospective method. The effect of initially applying the new revenue standard was immaterial. Based on the evaluation of its current collaboration agreement and associated revenue streams, revenue will be recorded consistently under both the current and the new standard. In June 2016, the FASB issued ASU 2016-13, Financial Instruments — Credit Losses — Measurement of Credit Losses on Financial Instruments . ASU 2016-13 changes the impairment model for most financial assets and certain other instruments. ASU 2016-13 is effective for annual and interim reporting periods beginning after December 15, 2019. The Company is in the process of evaluating the impact the adoption of this standard would have on its financial statements and disclosures. In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income that would permit entities to make a one-time reclassification from accumulated other comprehensive income (AOCI) to retained earnings for the stranded tax effects resulting from the newly enacted corporate tax rates under the Tax Cuts and Jobs Act (the "Act"), effective for the year ended December 31, 2017. The amount of the reclassification is calculated on the basis of the difference between the historical tax rate and newly enacted tax rate. The standard is effective for interim and annual periods beginning after December 15, 2018 with early adoption permitted. The Company is currently assessing the impact of this standard on its financial statements and disclosures

Cash Equivalents and Investment

Cash Equivalents and Investments	3 Months Ended
	Mar. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Cash Equivalents and Investments	Cash Equivalents and Investments At March 31, 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 months ended March 31, 2018 and 2017 and as a result, the Company did not reclassify any amounts out of accumulated other comprehensive income for the same periods. As of March 31, 2018, the Company’s long-term investments in U.S. Treasury securities have maturity dates less than 1.5 years. All of the Company’s available-for-sale securities are subject to a periodic impairment review. The Company considers an investment security to be impaired when its fair value is less than its carrying cost, in which case the Company would further review the investment to determine whether it is other-than-temporarily impaired. When the Company evaluates an investment for other-than-temporary impairment, the Company reviews factors such as the length of time and extent to which fair value has been below cost basis, the financial condition of the issuer and any changes thereto, intent to sell, and whether it is more likely than not the Company will be required to sell the investment before the recovery of its cost basis. If an investment is other-than-temporarily impaired, the Company writes it down through earnings to its impaired value and establishes that as a new cost basis for the investment. The Company did not identify any of its available-for-sale securities as other-than-temporarily impaired in any of the periods presented. As of March 31, 2018, no investment was in a continuous unrealized loss position for more than one year, the unrealized losses were not due to change in credit risk, and the Company believes that it is more likely than not the investments will be held until maturity. The following table summarizes the available‑for‑sale securities (in thousands): Amortized Cost Unrealized Gains Unrealized Losses Fair Value March 31, 2018 (unaudited) Money market funds $ 64,769 $ — $ — $ 64,769 Corporate notes 103,764 — (184 ) 103,580 Government notes 7,937 — (18 ) 7,919 Total $ 176,470 $ — $ (202 ) $ 176,268 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	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	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 Total Carrying Value Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) March 31, 2018 (unaudited) Assets: Money market funds $ 64,769 $ 64,769 $ — $ — Corporate notes 103,580 — 103,580 — Government notes 7,919 7,919 — — Total assets $ 176,268 $ 72,688 $ 103,580 $ — Fair Value Measurements Using Total Carrying Value Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2017: Assets: Money market funds $ 8,685 $ 8,685 $ — $ — Corporate notes 46,098 5,103 40,995 — Government notes 6,175 6,175 — — Total assets $ 60,958 $ 19,963 $ 40,995 $ — 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	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
License Agreements	License Agreements Merck License In December 2012, the Company entered into an exclusive worldwide royalty free license agreement with Merck Sharp & Dohme Corp., or “Merck” for exclusive worldwide rights for the development and commercialization of serlopitant and two other NK 1 ‑R antagonists in all human diseases, disorders or conditions, except for the treatment and prevention of nausea or vomiting. The Company paid Merck an upfront non‑refundable non‑creditable licensing fee of $1.0 million dollars and issued to Merck shares of its common stock. In addition, the Company has agreed to make aggregate payments of up to $25.0 million dollars upon the achievement of specified development and regulatory milestones. 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. Through March 31, 2018 , no milestones have been achieved under the license agreement with Merck. JT Torii Collaboration Agreement On August 10, 2016, the Company entered into a license and collaboration agreement with Japan Tobacco Inc. and Torii Pharmaceutical Co. Ltd., together referred to as “JT Torii”, which is referred to as the “Collaboration Agreement”. 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 is 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 include 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. The Company is reimbursed by JT Torii for the non-commercial supplies of serlopitant at the same rate it is charged by the third-party manufacturer for such supplies, which price does not include a significant or incremental discount for JT Torii. The assessment of performance obligations also requires 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 has determined that the license is not distinct from the research and development services because JT Torii cannot use the license with its available resources to obtain any economic value without the Company’s participation. T he license and the services are combined as one unit of accounting and upfront payments are recorded initially as deferred revenue in the balance sheet. Revenue is then recognized over an estimated performance period as performance of services is being completed. The Company is recognizing the upfront fee based on performance of the obligation using input method over the period of performance of six years, which represents the estimated development period in the territories based on the initial development plan managed by the joint steering committee. The term of the agreement is through the expiration of the patents associated with serlopitant. 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. Under the Collaboration Agreement, the Company is 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, relate to the preparation of an investigational new drug application (“IND”) for submission to regulatory authorities in the territory are 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. All other milestones, which amount to an aggregate of $24.0 million , are 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. 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 represents another contract that provides distinct goods and services to JT Torii. The fees received under the services agreement will be recognized as and when such services are performed by the Company and JT Torii consumes the benefits of those services. The Company has no obligation to provide services unless requested by JT Torii and agreed to by the Company. The Company is eligible to receive reimbursement of estimated costs incurred and payment for research services performed directly by the Company at agreed upon rates. During the quarter ended March 31, 2018, the Company recognized revenue of $48,000 in the statement of operations related to the services agreement. The services agreement terminates upon the termination of the Collaboration Agreement or by mutual agreement of the parties. Amounts received prior to satisfying the revenue recognition criteria are recorded as deferred revenue in the Company’s balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, current portion. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. Expenses related to the collaboration agreement are recorded as a component of research and development in the statement of operations as incurred, and to date have been immaterial. In April 2018, JT Torii informed the Company that they have decided to halt the recently initiated Japanese Phase 2 clinical trial of serlopitant. JT Torii has indicated that they are reevaluating their serlopitant development program based upon evolving commercial considerations in Japan. Based upon communication with JT Torii, the Company expects that the Collaboration Agreement for serlopitant will ultimately be terminated. If the Collaboration Agreement is terminated, the Company will accelerate recognition of deferred revenue under the agreement. In the second quarter of 2018, the Company expects to earn and recognize a $2.0 million milestone payment related to JT Torii’s receipt of IND-enabling past clinical study reports delivered by the Company under the agreement.

Balance Sheets Components

Balance Sheets Components	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheets Components	Balance Sheets Components Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): March 31, December 31, (unaudited) Accrued personnel expenses $ 470 $ 1,108 Accrued clinical and development expenses 2,506 2,250 Other 198 201 Total $ 3,174 $ 3,559

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	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 pending or threatened litigation. Leases The Company conducts its operations using leased office facilities. On April 6, 2016, the Company entered into a lease agreement. The twenty-six month lease, began on May 1, 2016, and provides 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. The thirty -month lease, beginning on October 1, 2017 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 for the three months ended March 31, 2018 and 2017 was $225,000 and $58,000 , respectively. As of March 31, 2018 , total future minimum lease payments under our operating leases are as follows (in thousands): 2018 $ 493 2019 675 2020 173 Total future minimum lease payments $ 1,341 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 March 31, 2018 . Contingencies From time to time, we may have certain contingent liabilities that arise in the ordinary course of our business activities. We accrue 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)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stockholders' Equity (Deficit)	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 on January 23, 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 for issuance pursuant to awards under the 2018 Plan 3,000,000 shares of our common stock. The Company adopted a 2018 Employee Stock Purchase Plan, or ESPP, effective on January 23, 2018. The ESPP will enable eligible employees of the Company and designated affiliates to purchase shares of common stock at a discount following its effectiveness. 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 March 31, 2018 2017 (unaudited) Research and development $ 426 $ 177 General and administrative 396 139 Total stock-based compensation expense $ 822 $ 316 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 Granted 5,600 31.58 Balances at March 31, 2018 2,505,754 $ 3.57 8.58 $ 85,225

Significant Accounting Polici14

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial information for the three months ended March 31, 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 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 our statement of financial position as of March 31, 2018 , our statements of operations and comprehensive loss for the three months ended March 31, 2018 and 2017 and our statements of cash flows for the three months ended March 31, 2018 and 2017. The results for the three months ended March 31, 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.
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 our 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. Under its collaboration agreement, the Company may receive milestone payments related to development and commercial achievements. 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, adjust the Company’s 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 does 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 months ended March 31, 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 February 2016, the FASB issued ASU 2016‑02, Leases (ASC 842), which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight‑line basis over the term of the lease, respectively. A lessee is also required to record a right‑of‑use asset and a lease liability for all leases with a term of greater than twelve months regardless of their classification. Leases with a term of twelve months or less will be accounted for similar to existing guidance for operating leases today. ASC 842 supersedes the previous leases standard, ASC 840 Leases . The standard is effective on January 1, 2019, with early adoption permitted. The Company is currently evaluating the effects, if any, that the adoption of this guidance will have on its financial statements. In May 2014, the FASB issued ASU No. 2014‑09, Revenue from Contracts with Customers (Topic 606) , which supersedes the revenue recognition requirements in ASC 605, Revenue Recognition . This ASU is based on the principle that revenue is recognized to depict the transfer of goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The ASU also requires additional disclosure about the nature, amount, timing and uncertainty of revenue and cash flows arising from customer contracts, including significant judgments and changes in judgments and assets recognized from costs incurred to obtain or fulfill a contract. In August 2015, FASB issued ASU No. 2015‑14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date , which effectively delayed the adoption date by one year, to an effective date for public entities for annual and interim periods beginning after December 15, 2017. In March, April and May 2016, the FASB issued additional updates to the new revenue standard relating to reporting revenue on a gross versus net basis, identifying performance obligations and licensing arrangements, and narrow‑scope improvements and practical expedients, respectively. The effective date of this additional update is the same as that of ASU 2014‑09. The guidance permits the use of either a full retrospective or modified retrospective method. The Company adopted the standard using the full retrospective method. The effect of initially applying the new revenue standard was immaterial. Based on the evaluation of its current collaboration agreement and associated revenue streams, revenue will be recorded consistently under both the current and the new standard. In June 2016, the FASB issued ASU 2016-13, Financial Instruments — Credit Losses — Measurement of Credit Losses on Financial Instruments . ASU 2016-13 changes the impairment model for most financial assets and certain other instruments. ASU 2016-13 is effective for annual and interim reporting periods beginning after December 15, 2019. The Company is in the process of evaluating the impact the adoption of this standard would have on its financial statements and disclosures. In February 2018, the FASB issued ASU 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income that would permit entities to make a one-time reclassification from accumulated other comprehensive income (AOCI) to retained earnings for the stranded tax effects resulting from the newly enacted corporate tax rates under the Tax Cuts and Jobs Act (the "Act"), effective for the year ended December 31, 2017. The amount of the reclassification is calculated on the basis of the difference between the historical tax rate and newly enacted tax rate. The standard is effective for interim and annual periods beginning after December 15, 2018 with early adoption permitted. The Company is currently assessing the impact of this standard on its financial statements and disclosures

Significant Accounting Polici15

Significant Accounting Policies Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2018 2017 (unaudited) Numerator: Net loss attributable to common stockholders, basic and diluted $ (12,657 ) $ (5,474 ) Denominator: Weighted-average common shares outstanding 17,709,274 5,280,058 Less: weighted-average common shares subject to repurchase (125,897 ) (208,337 ) Weighted-average common shares used to compute basic and diluted net loss per share 17,583,377 5,071,721 Net loss per share attributable to common stockholders Basic and diluted $ (0.72 ) $ (1.08 )
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: March 31, 2018 2017 (unaudited) Stock options available for issuance 3,731,172 1,123,911 Stock options outstanding 2,505,754 1,595,499 Outstanding common stock subject to repurchase 119,026 201,466 Convertible preferred stock issuable upon conversion to common stock — 5,234,800 Total 6,355,952 8,155,676

Cash Equivalents and Investme16

Cash Equivalents and Investments (Tables)	3 Months Ended
	Mar. 31, 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 March 31, 2018 (unaudited) Money market funds $ 64,769 $ — $ — $ 64,769 Corporate notes 103,764 — (184 ) 103,580 Government notes 7,937 — (18 ) 7,919 Total $ 176,470 $ — $ (202 ) $ 176,268 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)	3 Months Ended
	Mar. 31, 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 Total Carrying Value Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) March 31, 2018 (unaudited) Assets: Money market funds $ 64,769 $ 64,769 $ — $ — Corporate notes 103,580 — 103,580 — Government notes 7,919 7,919 — — Total assets $ 176,268 $ 72,688 $ 103,580 $ — Fair Value Measurements Using Total Carrying Value Quoted Prices in Active Markets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2017: Assets: Money market funds $ 8,685 $ 8,685 $ — $ — Corporate notes 46,098 5,103 40,995 — Government notes 6,175 6,175 — — Total assets $ 60,958 $ 19,963 $ 40,995 $ —

Balance Sheets Components (Tabl

Balance Sheets Components (Tables)	3 Months Ended
	Mar. 31, 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): March 31, December 31, (unaudited) Accrued personnel expenses $ 470 $ 1,108 Accrued clinical and development expenses 2,506 2,250 Other 198 201 Total $ 3,174 $ 3,559

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Operating Lease Payments	As of March 31, 2018 , total future minimum lease payments under our operating leases are as follows (in thousands): 2018 $ 493 2019 675 2020 173 Total future minimum lease payments $ 1,341

Stockholders' Equity (Deficit)

Stockholders' Equity (Deficit) (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based 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 March 31, 2018 2017 (unaudited) Research and development $ 426 $ 177 General and administrative 396 139 Total stock-based compensation expense $ 822 $ 316
Schedule of Stock Option 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 Granted 5,600 31.58 Balances at March 31, 2018 2,505,754 $ 3.57 8.58 $ 85,225

Formation and Business of the21

Formation and Business of the Company (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	Jan. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule of Capitalization, Equity [Line Items]
Net loss		$ 12,657	$ 5,474
Net cash used in operating activities		(11,290)	$ (5,584)
Cash, cash equivalents and investments		176,600
Accumulated deficit		$ (71,848)		$ (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 Polici22

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 Polici23

Significant Accounting Policies - Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Accounting Policies [Abstract]
Net loss attributable to common stockholders, basic	$ (12,657)	$ (5,474)
Weighted‑average common shares outstanding (shares)	17,709,274	5,280,058
Less: weighted‑average common shares subject to repurchase (shares)	(125,897)	(208,337)
Weighted‑average number of common shares used to compute basic and diluted net loss per share (in shares)	17,583,377	5,071,721
Basic and diluted (in USD per share)	$ (0.72)	$ (1.08)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the calculation of EPS	6,355,952	8,155,676
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	3,731,172	1,123,911
Stock options outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from the calculation of EPS	2,505,754	1,595,499
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	119,026	201,466
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	5,234,800

Cash Equivalents and Investme24

Cash Equivalents and Investments (Details)	3 Months Ended
	Mar. 31, 2018USD ($)investment	Mar. 31, 2017USD ($)
Schedule of Available-for-sale Securities [Line Items]
Realized gains (losses) recognized on the sale or maturity of available-for-sale securities | $	$ 0	$ 0
Securities in continuous unrealized loss position for more than one year | investment	0
US Treasury Securities
Schedule of Available-for-sale Securities [Line Items]
Investments, remaining maturity	1 year 6 months

Cash Equivalents and Investme25

Cash Equivalents and Investments - Available for Sale securities (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Money market funds, amortized cost	$ 78,527	$ 10,206	$ 6,029	$ 4,026
Amortized cost	176,470	61,009
Unrealized gains	0	0
Unrealized losses	(202)	(51)
Fair value	176,268	60,958
Corporate notes
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	103,764	46,133
Available-for-sale securities, unrealized gains	0	0
Available-for-sale securities, unrealized losses	(184)	(35)
Available-for-sale securities, fair value	103,580	46,098
Government notes
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale securities, amortized cost	7,937	6,191
Available-for-sale securities, unrealized gains	0	0
Available-for-sale securities, unrealized losses	(18)	(16)
Available-for-sale securities, fair value	7,919	6,175
Money market funds
Schedule of Available-for-sale Securities [Line Items]
Money market funds, amortized cost	64,769	8,685
Money market funds, unrealized gains	0	0
Money market funds, unrealized losses	0	0
Money market funds, fair value	$ 64,769	$ 8,685

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	$ 176,268	$ 60,958
Fair Value Measurements | Quoted Prices in Active Markets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	72,688	19,963
Fair Value Measurements | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	103,580	40,995
Fair Value Measurements | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
Corporate notes | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	103,580	46,098
Corporate notes | Fair Value Measurements | Quoted Prices in Active Markets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	0	5,103
Corporate notes | Fair Value Measurements | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	103,580	40,995
Corporate notes | Fair Value Measurements | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	0	0
Government notes | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	7,919	6,175
Government notes | Fair Value Measurements | Quoted Prices in Active Markets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	7,919	6,175
Government notes | Fair Value Measurements | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	0	0
Government notes | Fair Value Measurements | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	0	0
Money market funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market funds	64,769	8,685
Money market funds | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market funds	64,769	8,685
Money market funds | Fair Value Measurements | Quoted Prices in Active Markets (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market funds	64,769	8,685
Money market funds | Fair Value Measurements | Significant Other Observable Inputs (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market funds	0	0
Money market funds | Fair Value Measurements | Significant Unobservable Inputs (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Money market funds	$ 0	$ 0

License Agreements (Details)

License Agreements (Details) - USD ($) $ in Thousands	Aug. 10, 2016	Apr. 30, 2018	Dec. 31, 2012	Mar. 31, 2018
Merck
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Licensing fee			$ 1,000
Merck | Development and Regulatory Milestones
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangements, potential milestone payments			$ 25,000
JT Torii | Development and Regulatory Milestones
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangements, potential milestone proceeds	$ 28,000
JT Torii | Collaboration Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative agreement, upfront payment received	$ 11,000
Collaborative arrangements, revenue recognition, initial performance period	6 years
JT Torii | Commercial Milestone
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangements, potential milestone proceeds	$ 15,000
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
JT Torii | Non-substantive Milestones [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaborative arrangements, potential milestone proceeds	$ 24,000
Research and Development Arrangement | JT Torii
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development arrangement, contract to perform for others, compensation earned				$ 48
Research and Development Arrangement | Subsequent Event | JT Torii
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development arrangement, contract to perform for others, compensation earned		$ 2,000

Balance Sheets Components (Deta

Balance Sheets Components (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued personnel expenses	$ 470	$ 1,108
Accrued clinical and development expenses	2,506	2,250
Other	198	201
Total	$ 3,174	$ 3,559

Commitments and Contingencies29

Commitments and Contingencies (Details) ft² in Thousands, $ in Thousands	Oct. 01, 2017USD ($)ft²	May 01, 2016USD ($)ft²	Mar. 31, 2018USD ($)	Mar. 31, 2017USD ($)
Acquired Indefinite-lived Intangible Assets [Line Items]
Operating lease, rent expense			$ 225	$ 58
Menlo Park, California
Acquired Indefinite-lived Intangible Assets [Line Items]
Operating lease, term of contract		26 months
Leased office space, square footage | ft²		4
Operating lease, monthly expense		$ 20
Redwood City, California
Acquired Indefinite-lived Intangible Assets [Line Items]
Operating lease, term of contract	30 months
Leased office space, square footage | ft²	14
Operating lease, monthly expense	$ 55

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Operating Lease Payments (Details) $ in Thousands	Mar. 31, 2018USD ($)
Year ending December 31:
2,018	$ 493
2,019	675
2,020	173
Total future minimum lease payments	$ 1,341

Stockholders' Equity (Deficit31

Stockholders' Equity (Deficit) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 23, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock‑based compensation expense	$ 822	$ 316
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock‑based compensation expense	426	177
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock‑based compensation expense	$ 396	$ 139
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
2018 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available under the Plan (shares)			325,000

Stockholders' Equity (Deficit32

Stockholders' Equity (Deficit) - Stock Option and Restricted Stock Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Balances, beginning (shares)	2,506,926
Forfeited (shares)	(6,772)
Granted (shares)	5,600
Balances, ending (shares)	2,505,754	2,506,926
Outstanding, exercise price per share (in USD per share)	$ 3.57	$ 3.50
Forfeited, exercise price per share (in USD per share)	7.01
Granted, exercise price per share (in USD per share)	$ 31.58
Options outstanding, weighted average remaining contractual term	8 years 6 months 29 days	8 years 9 months 15 days
Options outstanding, aggregate intrinsic value	$ 85,225	$ 24,033