Quince Therapeutics (QNCX) 10-Q 12 Jun 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Jun. 12, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Trading Symbol	CRTX
Entity Registrant Name	Cortexyme, Inc.
Entity Central Index Key	0001662774
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		26,841,149

Condensed Balance Sheets (Unaud

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 20,634	$ 24,872
Short term investments	38,410	46,844
Restricted cash	250
Prepaid expenses and other current assets	4,496	868
Total current assets	63,790	72,584
Property and equipment, net	314	283
Right-of-use asset	815
Long term investments	5,416
Other assets	261	10
Total assets	70,596	72,877
Current liabilities:
Accounts Payable	1,946	495
Accrued expenses and other current liabilities	1,724	962
Short-term lease liability	340
Total current liabilities	4,010	1,457
Long-term lease liability	475
Total liabilities	4,485	1,457
Commitments and contingencies (Note 6)
Stockholders’ deficit:
Common stock, $0.001 par value, 24,794,114 and 24,794,114 shares authorized, 3,566,923 and 3,412,366 issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	4	3
Additional paid in capital	498	245
Accumulated other comprehensive loss	(23)	(49)
Accumulated deficit	(38,506)	(32,825)
Total stockholders’ deficit	(38,027)	(32,626)
Total liabilities, redeemable convertible preferred stock and stockholders’ deficit	70,596	72,877
Series A Redeemable Convertible Preferred Stock
Current liabilities:
Series A redeemable convertible preferred stock, par value $0.001, 9,008,931 shares authorized, 9,008,919 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively; liquidation preference of $17,178 at March 31, 2019 and December 31, 2018, respectively	17,178	17,178
Series B Redeemable Convertible Preferred Stock
Current liabilities:
Series A redeemable convertible preferred stock, par value $0.001, 9,008,931 shares authorized, 9,008,919 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively; liquidation preference of $17,178 at March 31, 2019 and December 31, 2018, respectively	$ 86,960	$ 86,868

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	24,794,114	24,794,114
Common stock, shares issued	3,566,923	3,412,366
Common stock, shares outstanding	3,566,923	3,412,366
Series A Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized	9,008,931	9,008,931
Redeemable convertible preferred stock, shares issued	9,008,919	9,008,919
Redeemable convertible preferred stock, shares outstanding	9,008,919	9,008,919
Redeemable convertible preferred stock, liquidation preference	$ 17,178	$ 17,178
Series B Redeemable Convertible Preferred Stock
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized	9,430,145	9,430,145
Redeemable convertible preferred stock, shares issued	9,152,108	9,152,108
Redeemable convertible preferred stock, shares outstanding	9,152,108	9,152,108
Redeemable convertible preferred stock, liquidation preference	$ 87,972	$ 87,972

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating expenses:
Research and development	$ 4,825	$ 2,413
General and administrative	1,250	347
Total operating expenses	6,075	2,760
Loss from operations	(6,075)	(2,760)
Interest income	394
Interest expense		(599)
Change in fair value of derivative liability		(18)
Net loss	(5,681)	(3,377)
Other comprehensive loss:
Unrealized gain on available for sales securities	26
Total comprehensive loss	$ (5,655)	$ (3,377)
Net loss per share - basic and diluted	$ (1.61)	$ (1.01)
Weighted average shares of common stock outstanding - basic and diluted	3,521,045	3,359,989

Condensed Statements of Redeema

Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders' Deficit (Unaudited) - USD ($) $ in Thousands	Total	Series A Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock	Common Stock	Additional Paid in Capital	Other Comprehensive Income / (Loss)	Accumulated Deficit
Beginning balance at Dec. 31, 2017	$ (20,280)			$ 3	$ 66		$ (20,349)
Beginning balance, shares at Dec. 31, 2017		9,008,919
Beginning balance at Dec. 31, 2017		$ 17,178
Beginning balance, shares at Dec. 31, 2017				3,361,016
Stock based compensation	13				13
Net Loss	(3,377)						(3,377)
Ending balance at Mar. 31, 2018	(23,644)			$ 3	79		(23,726)
Ending balance, shares at Mar. 31, 2018		9,008,919
Ending balance at Mar. 31, 2018		$ 17,178
Ending balance, shares at Mar. 31, 2018				3,361,016
Beginning balance at Dec. 31, 2018	(32,626)			$ 3	245	$ (49)	(32,825)
Beginning balance, shares at Dec. 31, 2018		9,008,919	9,152,108
Beginning balance at Dec. 31, 2018		$ 17,178	$ 86,868
Beginning balance, shares at Dec. 31, 2018				3,412,366
Exercise of stock options	64			$ 1	63
Exercise of stock options, shares				154,557
Stock based compensation	190				190
Vesting of Series B redeemable convertible preferred stock in lieu of rent			$ 92
Other Comprehensive Income	26					26
Net Loss	(5,681)						(5,681)
Ending balance at Mar. 31, 2019	$ (38,027)			$ 4	$ 498	$ (23)	$ (38,506)
Ending balance, shares at Mar. 31, 2019		9,008,919	9,152,108
Ending balance at Mar. 31, 2019		$ 17,178	$ 86,960
Ending balance, shares at Mar. 31, 2019				3,566,923

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities
Net Loss	$ (5,681)	$ (3,377)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash interest expense related to convertible promissory notes		159
Non-cash rent expense	92
Stock based compensation	190	13
Depreciation and amortization	19	8
Accretion of discount on convertible promissory notes payable		440
Amortization of discount on available for sale investments	(171)
Change in fair value of derivative liability		18
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(3,628)	(80)
Other assets	(250)
Accounts payable	1,451	(82)
Accrued expenses and other current liabilities	762	(276)
Net cash used in operating activities	(7,216)	(3,177)
Cash flow from investing activities:
Purchase of investments	(25,585)
Proceeds from maturities of investments	28,800
Purchase of property and equipment	(51)
Net cash provided by investing activities	3,164
Cash flows from financing activities:
Proceeds from issuance of convertible promissory note payable		250
Proceeds from issuance of commons stock upon exercise of stock options	64
Deferred Series B redeemable convertible preferred stock offering costs		(12)
Net cash provided by financing activities	64	238
Net increase / (decrease) in cash, cash equivalents and restricted cash	(3,988)	(2,939)
Cash, cash equivalents and restricted cash at beginning of period	24,872	7,393
Cash, cash equivalents and restricted cash at end of period	20,884	$ 4,454
Supplemental disclosures of non-cash information:
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 815

Organization

Organization	3 Months Ended
	Mar. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization	Note 1. Organization Description of Business Cortexyme, Inc. (the “Company”) was incorporated in the State of Delaware in June 2012 and is headquartered in South San Francisco, California. The Company is a clinical stage biopharmaceutical company focused on developing therapeutics based on data supporting a new theory of the cause of Alzheimer’s disease and other degenerative disorders. Cortexyme is targeting a specific, infectious pathogen tied to neurodegeneration and chronic inflammation in humans and animal models. Reverse Stock Split On April 25, 2019, the Company’s Board of Directors approved a one-for-0.367647 reverse split of the Company’s issued and outstanding common stock, redeemable convertible preferred stock, and stock options. The par value of the common stock was not adjusted as a result of the reverse stock split. All share and per share amounts in the accompanying unaudited condensed financial statements and notes to the unaudited condensed financial statements have been retroactively adjusted for all periods presented to reflect the reverse stock split. Initial Public Offering On May 8, 2019, the Company’s registration statement on Form S-1 (File No. 333-230853) for its initial public offering of common stock (“IPO”) was declared effective by the Securities and Exchange Commission (“SEC”). On May 13, 2019, the Company closed its IPO with the sale of 5,073,800 shares of common stock, which included 661,800 shares of common stock issued upon the exercise in full of the underwriters’ option to purchase additional shares, at a public offering price of $17.00 per share, resulting in net proceeds of $78.1 million, after deducting underwriting discounts and commissions and estimated offering expenses paid by the Company. In addition, in connection with the closing of the IPO, all of the Company’s outstanding shares of redeemable convertible preferred stock were automatically converted into 18,161,027 shares of common stock, and there are no shares of redeemable convertible preferred stock outstanding. As of March 31, 2019, the Company had incurred $1.1 million of deferred offering costs which are included in prepaid expenses and other current assets on the balance sheet and will be offset against the net proceeds received from the sale of common stock. Liquidity and Capital Resources The Company has incurred losses and negative cash flows from operations since inception and expects to continue to generate operating losses for the foreseeable future. As of March 31, 2019, the Company had an accumulated deficit of $38.5 million. Since inception through March 31, 2019, the Company has funded operations primarily with the net proceeds of the convertible promissory notes and from the issuance of redeemable convertible preferred stock. As of March 31, 2019, the Company had cash, cash equivalents, and short-term investments of $59.0 million, which it believes will be sufficient to fund its planned operations for a period of at least 12 months from the date of the issuance of the accompanying unaudited financial statements. Management expects to incur additional losses in the future to fund its operations and conduct product research and development and may need to raise additional capital to fully implement its business plan. The Company may raise additional capital through the issuance of equity securities, debt financings or other sources in order to further implement its business plan. However, if such financing is not available when needed and at adequate levels, the Company will need to reevaluate its operating plan and may be required to delay the development of its product candidate.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Note 2. Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and pursuant to the instructions of the SEC on The condensed balance sheet as of March 31, 2019, the condensed statements of operations and comprehensive loss for the three months ended March 31, 2019 and 2018, the condensed statements of stockholders’ deficit as of March 31, 2019 and 2018, the condensed statements of cash flows for the three months ended March 31, 2019 and 2018, and the financial data and other financial information disclosed in the notes to the condensed financial statements are unaudited. These financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2018 included in the Company’s final prospectus filed with the SEC on May 9, 2019. Use of Estimates The preparation of the Company’s financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and expenses, as well as related disclosure of contingent assets and liabilities. The most significant estimates used in the Company’s financial statements relate to the determination of the fair value of common stock and stock-based awards and other issuances, valuation of derivative instruments, accruals for research and development costs, useful lives of long-lived assets, stock-based compensation and related assumptions, the incremental borrowing rate for leases and income tax uncertainties, including a valuation allowance for deferred tax assets; and contingencies. The Company bases its estimates on historical experience and on various other market specific and other relevant assumptions that it believes 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 the Company’s estimates. Significant Accounting Policies There have been no significant changes to the accounting policies during the three months ended March 31, 2019, as compared to the significant accounting policies described in the Company’s final prospectus, dated May 8, 2019 and filed pursuant to Rule 424(b) under the Securities Act of 1933, as amended (the “Securities Act”). Cash, Cash Equivalents, and Restricted Cash The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash and cash equivalents. Cash equivalents, which consist of amounts invested in money market funds, are stated at fair value. There are no unrealized gains or losses on the money market funds for the periods presented. Restricted cash as of March 31, 2019 relates to a compensating balance to secure a credit card facility. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed balance sheets that sum to the total of the same amounts shown in the condensed statements of cash flows (in thousands): Three Months Ended March 31, 2019 2018 Cash and cash equivalents $ 20,634 $ 4,404 Restricted cash 250 50 Total cash, cash equivalents and restricted cash $ 20,884 $ 4,454 Fair Value Measurements The fair value of our financial instruments reflects the amounts that we estimate we 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). We disclose and recognize the fair value of our Level 1 - Inputs that reflect unadjusted quoted prices in active markets for identical assets or liabilities that we have 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. Our 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 years 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. Leases In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update, or ASU, No. 2016-02, Leases (Topic 842), to enhance the transparency and comparability of financial reporting related to leasing arrangements. The Company adopted the standard effective January 1, 2019. The Company determines if an arrangement includes a lease at inception. Right-of-use assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. The right-of-use asset includes any lease payments made and excludes lease incentives. Incremental borrowing rate is used in determining the present value of future payments. The Company utilizes its incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. The lease terms may include options to extend or terminate the lease. Lease expense for minimum lease payments is recognized on a straight-line basis over the non-cancelable lease term. Prior period amounts have not been adjusted and continue to be reported in accordance with the Company’s historical accounting under previous lease guidance, ASC 840, Leases (Topic 840). Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to not use this extended transition period for complying with certain new or revised accounting standards that have different effective dates for public and private companies. Recent Accounting Pronouncements adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This ASU requires that substantially all leases be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. The ASU is effective for interim and annual periods beginning after December 15, 2018. Additionally, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, which offers an additional transition method whereby entities may apply the new leases standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings rather than application of the new leases standard at the beginning of the earliest period presented in the financial statements. The Company elected this transition method and adopted ASC 842 on January 1, 2019 and as a result, recorded a right-of-use asset of $0.9 million, a short-term lease liability of $0.3 million, and a long-term lease liability of $0.6 million and no cumulative effect adjustment was made to the retained earnings as of the adoption date. The Company also elected the package of practical expedients under the transition guidance that will retain the historical lease classification and initial direct costs for any leases that exist prior to adoption of the new guidance and the practical expedient to not separate lease and nonlease components. See Note 5 for further disclosure. In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815) I. Accounting for Certain Financial Instruments with Down Round Features II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (“ASU 2017-11”). Part I applies to entities that issue financial instruments such as warrants, convertible debt or redeemable convertible preferred stock that contain down-round features. Part II replaces the indefinite deferral for certain mandatorily redeemable noncontrolling interests and mandatorily redeemable financial instruments of nonpublic entities contained within ASC Topic 480 with a scope exception and does not impact the accounting for these mandatorily redeemable instruments. For public entities, ASU 2017-11 is required to be adopted for annual periods beginning after December 15, 2018, including interim periods within those fiscal years. The adoption of ASU 2017-11 did not have any impact on the Company’s financial statements since the Company did not have any instruments subject to the scope of the ASU. Recent accounting pronouncements not yet adopted The following are new accounting pronouncements that the Company is evaluating for future impacts on its financial statements: Fair Value Measurement—Disclosure Framework: In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. The new guidance changes disclosure requirements related to fair value measurements as part of the disclosure framework project. The disclosure framework project aims to improve the effectiveness of disclosures in the notes to the financial statements by focusing on requirements that clearly communicate the most important information to users of the financial statements. This guidance is effective for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is evaluating the provisions of the updated guidance and assessing the impact on its financial statements. Financial Instruments—Credit Losses: In June 2016, the FASB issued new guidance which amends the principles around the recognition of credit losses by mandating entities incorporate an estimate of current expected credit losses when determining the value of certain assets. The guidance also amends reporting around allowances for credit losses on available-for-sale marketable securities. This guidance is effective for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is evaluating the provisions of the updated guidance and assessing the impact on its financial statements. In August 2018, the FASB issued Accounting Standards Update No. 2018-15, Intangibles – Goodwill and other – Internal-Use Software (Subtopic 350-40), which amended its guidance for costs of implementing a cloud computing service arrangement and aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. This new standard also requires customers to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement. The guidance is effective for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is evaluating the impact of adopting this amendment to its financial statements.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Note 3. Fair Value Measurements The Company measures and reports its cash equivalents, restricted cash, and investments at fair value. Money market funds are measured at fair value on a recurring basis using quoted prices and are classified as Level 1. Investments are measured at fair value based on inputs other than quoted prices that are derived from observable market data and are classified as Level 2 inputs. Financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used in such measurements by major security type as of March 31, 2019 and December 31, 2018 are presented in the following tables (in thousands): Fair Value Measurements at March 31, 2019 Fair Value Hierarchy Amortized Cost Unrealized Gains Unrealized Losses Fair Value Money market funds Level 1 $ 3,565 $ — $ — $ 3,565 Certificates of Deposit Level 2 11,025 1 (2 ) 11,024 Repurchase Agreements Level 2 12,000 — — 12,000 Commercial paper Level 2 5,388 — — 5,388 Corporate notes Level 2 8,386 — (1 ) 8,385 U.S. government notes Level 2 12,588 1 (5 ) 12,584 Asset backed securities Level 2 7,443 3 (20 ) 7,426 Total cash equivalents and investments $ 60,395 $ 5 $ (28 ) $ 60,372 Classified as: Cash equivalents $ 16,546 Short-term investments 38,410 Long-term investments 5,416 Total cash equivalents and investments $ 60,372 Fair Value Measurements at December 31, 2018 Fair Value Hierarchy Amortized Cost Unrealized Gains Unrealized Losses Fair Value Money market funds Level 1 $ 11,815 $ — $ — $ 11,815 Commercial paper Level 2 14,362 — (2 ) 14,360 Corporate notes Level 2 16,129 — (18 ) 16,111 U.S. government notes Level 2 8,980 — (1 ) 8,979 Asset backed securities Level 2 9,220 — (28 ) 9,192 Total cash equivalents and investments $ 60,506 $ — $ (49 ) $ 60,457 Classified as: Cash equivalents $ 13,613 Short-term investments 46,844 Total cash equivalents and investments $ 60,457 As of March 31, 2019, the remaining contractual maturities of available-for-sale securities were less than five months. There have been no significant realized losses on available-for-sale securities for the period presented. Based on the Company’s review of its available-for-sale securities, the Company believes it had no other-than-temporary impairments on these securities as of March 31, 2019, because the Company does not intend to sell these securities nor does the Company believe that it will be required to sell these securities before the recovery of their amortized cost basis. There were no transfers between Levels 1, 2 or 3 for the period presented.

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2019
Balance Sheet Components [Abstract]
Balance Sheet Components	Note 4. Balance Sheet Components Prepaid expenses and Other Current Assets Prepaid expenses and Other Current Assets consist of the following (in thousands): March 31, December 31, 2019 2018 Prepaid expenses $ 243 $ 13 Deferred issuance costs 1,128 34 Prepaid clinical trial expenses 2,678 587 Prepaid research and development expenses 60 166 Other assets 387 68 Total prepaid expenses and other current assets $ 4,496 $ 868 Property and Equipment Property and Equipment consist of the following (in thousands): March 31, December 31, 2019 2018 Lab Equipment $ 428 $ 378 Less: accumulated depreciation (114 ) (95 ) Property and equipment, net $ 314 $ 283 Accrued Liabilities Accrued liabilities consist of the following (in thousands): March 31, December 31, 2019 2018 Personnel expenses $ 182 $ 483 Professional fees 385 75 Research and development expenses 1,136 380 Other 21 24 Total accrued liabilities $ 1,724 $ 962

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Note 5. Leases As described in “Note 2 Summary of Significant Accounting Policies, Real Estate Operating Lease In June 2018, the Company entered into a three-year lease agreement with no renewal options with a related party, one of the investors in the Series B redeemable convertible preferred stock. The lease began on July 16, 2018 and provides 3,185 square feet of office and laboratory space in South San Francisco, California. The Company issued 114,437 shares of its Series B redeemable convertible preferred stock with a fair value of $1.1 million in exchange for the leased facility. No other payments are due under the lease. 100% of the issued shares were initially subject to a repurchase option. Each month beginning on the one-month anniversary of the commencement date of the lease, 1/36 th In the event of a termination of the lease for any reason other than (i) a material, uncured default of the tenant or (ii) the voluntary or involuntary liquidation, dissolution or winding up of the tenant, the Company has an irrevocable exclusive option for a period of three months from the termination to repurchase any unvested shares. In the event of (i) or (ii) above or an acquisition or initial public offering of the tenant, any unvested shares will fully and immediately vest, and any repurchase option will lapse in respect to any unvested shares. The Company recognizes lease expense on a straight-line basis over the term of its operating lease. The common area maintenance and other operating costs are included in the base rent . As of March 31, 2019, 89,006 unvested shares were subject to the repurchase option representing $856,000 of future rent expense to be recognized over the remaining term of 28 months on a straight-line basis over the respective lease period. As described in “Note 10 Subsequent Events”, the Company has completed its IPO on May 13, 2019. As there will be no unvested shares upon the initial public offering, the operating lease liability balance will be fully extinguished. Maturities of the lease liabilities as of March 31, 2019 are presented in the following table (in thousands): Year: 2019 (excluding the three months ended March 31, 2019) $ 275 2020 366 2021 214 Total liabilities 855 Less imputed interest (40 ) Total $ 815 Reported as: Operating lease liabilities $ 340 Operating lease liabilities, net of current portion 475 Total lease liability $ 815 The Company determined its operating lease liabilities for operating lease using a discount rate of 4.00% based on the rate that the Company would have to pay to borrow on a collateralized basis for a similar lease an amount equal to the lease payments in a similar economic environment. Lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. As of March 31, 2019, the weighted-average remaining lease term was 2.40 years. Rent expense for the operating lease for the three months ended March 31, 2019 was $92,000.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	Note 6. Stock-Based Compensation In 2014, the Company adopted the 2014 Stock Plan (the 2014 Plan) under which 2,973,736 shares of the Company’s common stock have been reserved for issuance to employees, directors and consultants. Under the 2014 Plan, the Board of Directors may grant incentive stock options or non-statutory stock options. Incentive stock options may only be granted to Company employees. The exercise price of incentive stock options and non- statutory stock options will be no less than 100% of the fair value per share of the Company’s common stock on the grant date. If an individual owns capital stock representing more than 10% of the outstanding shares, the price of each share will be at 110% of the fair value. Fair value is determined by the Board of Directors. Options expire after ten years (five years for stockholders owning greater than 10% of all classes of stock). For options that have been exercised prior to vesting, the Company has a repurchase option exercisable upon the voluntary or involuntary termination of the purchaser’s employment with the Company for any reason. As noted in Note 10 Subsequent Events, our 2014 Stock Plan was amended, restated and re-named the 2019 Equity Incentive Plan, or 2019 Plan, by our board of directors on April 24, 2019 and our stockholders on April 25, 2019. The 2019 Plan became effective on May 7, 2019. For the three months ended March 31, 2019, the Company recognized $190,000 of stock-based compensation expense related to options granted to employees and non-employees. The compensation expense is allocated on a departmental basis, based on the classification of the option holder. No income tax benefits have been recognized in the statement of operations for stock-based compensation arrangements. Number of Options and Unvested Shares Weighted Average Exercise Price Weighted average remaining contractual life (years) Aggregate intrinsic value Balance at December 31, 2018 1,885,504 1.57 9.07 1,252,496 Options granted 397,055 6.91 9.87 Options exercised (154,557 ) 0.41 Options cancelled (66,180 ) 2.23 Balance at March 31, 2019 2,061,822 2.66 9.20 8,759,422 Options vested and expected to vest as of March 31, 2019 2,061,822 2.66 9.20 8,759,422 Options exercisable as of March 31, 2019 1,003,660 0.82 8.05 6,114,427 The total unrecognized share-based compensation cost at March 31, 2019 amounted to approximately $3,155,694 which is expected to be recognized over the next four years.

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	Note 7. Related Party Transactions In June 2014, the Company entered into a research grant and license agreement (the Agreement) with a stockholder of the Company. The Agreement requires the Company to pay royalties to the stockholder in the amount of 3% of gross revenues not to exceed $1.05 million. This agreement was amended in April 2019 and the royalty payment provision was removed. As described in Note 5, the Company entered into a three-year lease agreement with a Series B redeemable preferred stock investor. The lease began on July 16, 2018 and provides 3,185 square feet of office space in South San Francisco, California. The Company issued 114,437 restricted shares of its Series B redeemable convertible preferred stock in exchange for the leased facility. During the three months ended March 31, 2019, 9,537 shares vested under the lease agreement. As described in Note 1, the Company completed its IPO in May 2019. As a result of the IPO, 82,649 shares of previously restricted Series B redeemable convertible preferred stock under the lease agreement became fully vested and were converted to common stock.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Note 8. Income Taxes The Company has a history of losses and expects to record a loss in 2019. The Company accounts for income taxes under standards issued by the FASB. Under those standards, deferred tax assets and liabilities are recognized for future tax benefits or consequences attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. A valuation allowance is provided for significant deferred tax assets when it is more likely than not that such assets will not be realized through future operations. No provision for income taxes has been recorded due to the available net operating loss carry forwards of approximately $28 million will begin to expire in 2034. Future tax benefits which may arise as a result of these losses have not been recognized in these financial statements, as their realization is determined not likely to occur and accordingly, the Company has recorded a valuation allowance for the future deferred tax assets.

Net Loss Per Share

Net Loss Per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Net Loss Per Share	Note 9. Net Loss Per Share The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share for the period presented due to their anti-dilutive effect: March 31, 2019 2018 Series A redeemable convertible preferred stock 9,008,919 9,008,919 Series B redeemable convertible preferred stock 9,152,108 — Warrants 27,941 27,941 Options issued and outstanding 2,061,822 879,696 Total 20,250,790 9,916,556

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Note 10. Subsequent Events In May 2019, the Company completed an initial public offering (“IPO”) through issuing and selling 5,073,800 shares of common stock at a public offering price of $17.00 per share, including 661,800 shares sold pursuant to the underwriters’ full exercise of their option to purchase additional shares. The aggregate net proceeds received by the Company from the offering, net of underwriting discounts and commissions and offering expenses, was approximately $78.1 million. Upon the closing of the IPO, all of the outstanding shares of redeemable convertible preferred stock automatically converted into 18,161,027 shares of common stock. Subsequent to the closing of the IPO, there were no shares of redeemable convertible preferred stock outstanding. In April 2019, the Company’s 2014 Stock Plan was amended, restated and re-named the 2019 Equity Incentive Plan (the “2019 Plan”), by the Company’s board of directors and the Company’s stockholders. The 2019 Plan became effective on May 7, 2019, the day prior to the effectiveness of the registration statement filed in connection with the IPO. Under the 2019 Plan, the Company may grant stock options, stock appreciation rights, restricted stock, restricted stock units, performance units, and performance shares to individuals who are then employees, officers, directors or consultants of the Company, and employees and consultants of the Company’s subsidiaries. A total of 5,131,549 shares of common stock were approved to be initially reserved for issuance under the 2019 Plan. The number of shares that remained available for issuance under the 2014 Plan as of the effective date of the 2019 Plan and shares subject to outstanding awards under the 2014 Plan as of the effective date of the 2019 Plan that are subsequently canceled, forfeited or repurchased by the Company will be added to the shares reserved under the 2019 Plan. In addition, the number of shares of common stock available for issuance under the 2019 Plan will be automatically increased on the first day of each calendar year during the ten-year term of the 2019 Plan, beginning with January 1, 2020 and ending with January 1, 2029, by an amount equal to the least of 4% of the outstanding number of shares of the Company’s common stock on December 31st of the preceding calendar year, 2,146,354 shares or such lesser amount as determined by the Company’s board of directors. The Company’s Employee Stock Purchase Plan, or 2019 ESPP, was adopted by the Company’s board of directors on April 24, 2019 and approved by the Company’s stockholders on April 25, 2019. The 2019 ESPP became effective on May 7, 2019. The Company reserved 268,295 shares of its common stock for issuance under the 2019 ESPP. The number of shares reserved for issuance under the 2019 ESPP will be increased automatically on the first day of each fiscal year for a period of up to ten years, starting with the 2020 fiscal year. The ESPP has not yet been implemented and it may or may not be implemented at the discretion of the Company. The Company has completed an evaluation of all subsequent events through the date these financial were issued to ensure that these financial statements include appropriate disclosure of events both recognized in the financial statements and events which occurred but were not recognized in the financial statements.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and pursuant to the instructions of the SEC on The condensed balance sheet as of March 31, 2019, the condensed statements of operations and comprehensive loss for the three months ended March 31, 2019 and 2018, the condensed statements of stockholders’ deficit as of March 31, 2019 and 2018, the condensed statements of cash flows for the three months ended March 31, 2019 and 2018, and the financial data and other financial information disclosed in the notes to the condensed financial statements are unaudited. These financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto for the year ended December 31, 2018 included in the Company’s final prospectus filed with the SEC on May 9, 2019.
Use of Estimates	Use of Estimates The preparation of the Company’s financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, and expenses, as well as related disclosure of contingent assets and liabilities. The most significant estimates used in the Company’s financial statements relate to the determination of the fair value of common stock and stock-based awards and other issuances, valuation of derivative instruments, accruals for research and development costs, useful lives of long-lived assets, stock-based compensation and related assumptions, the incremental borrowing rate for leases and income tax uncertainties, including a valuation allowance for deferred tax assets; and contingencies. The Company bases its estimates on historical experience and on various other market specific and other relevant assumptions that it believes 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 the Company’s estimates.
Significant Accounting Policies	Significant Accounting Policies There have been no significant changes to the accounting policies during the three months ended March 31, 2019, as compared to the significant accounting policies described in the Company’s final prospectus, dated May 8, 2019 and filed pursuant to Rule 424(b) under the Securities Act of 1933, as amended (the “Securities Act”).
Cash, Cash Equivalents, and Restricted Cash	Cash, Cash Equivalents, and Restricted Cash The Company considers all highly liquid investments with original maturities of three months or less at the date of purchase to be cash and cash equivalents. Cash equivalents, which consist of amounts invested in money market funds, are stated at fair value. There are no unrealized gains or losses on the money market funds for the periods presented. Restricted cash as of March 31, 2019 relates to a compensating balance to secure a credit card facility. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed balance sheets that sum to the total of the same amounts shown in the condensed statements of cash flows (in thousands): Three Months Ended March 31, 2019 2018 Cash and cash equivalents $ 20,634 $ 4,404 Restricted cash 250 50 Total cash, cash equivalents and restricted cash $ 20,884 $ 4,454
Fair Value Measurements	Fair Value Measurements The fair value of our financial instruments reflects the amounts that we estimate we 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). We disclose and recognize the fair value of our Level 1 - Inputs that reflect unadjusted quoted prices in active markets for identical assets or liabilities that we have 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. Our 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 years 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.
Leases	Leases In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update, or ASU, No. 2016-02, Leases (Topic 842), to enhance the transparency and comparability of financial reporting related to leasing arrangements. The Company adopted the standard effective January 1, 2019. The Company determines if an arrangement includes a lease at inception. Right-of-use assets and lease liabilities are recognized based on the present value of the future minimum lease payments over the lease term at the commencement date. The right-of-use asset includes any lease payments made and excludes lease incentives. Incremental borrowing rate is used in determining the present value of future payments. The Company utilizes its incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. The lease terms may include options to extend or terminate the lease. Lease expense for minimum lease payments is recognized on a straight-line basis over the non-cancelable lease term. Prior period amounts have not been adjusted and continue to be reported in accordance with the Company’s historical accounting under previous lease guidance, ASC 840, Leases (Topic 840).
Emerging Growth Company Status	Emerging Growth Company Status The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act until such time as those standards apply to private companies. The Company has elected to not use this extended transition period for complying with certain new or revised accounting standards that have different effective dates for public and private companies.
Recently Accounting Pronouncements adopted and Recent accounting pronouncements not yet adopted	Recent Accounting Pronouncements adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This ASU requires that substantially all leases be recognized by lessees on their balance sheet as a right-of-use asset and corresponding lease liability, including leases currently accounted for as operating leases. The ASU is effective for interim and annual periods beginning after December 15, 2018. Additionally, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, which offers an additional transition method whereby entities may apply the new leases standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings rather than application of the new leases standard at the beginning of the earliest period presented in the financial statements. The Company elected this transition method and adopted ASC 842 on January 1, 2019 and as a result, recorded a right-of-use asset of $0.9 million, a short-term lease liability of $0.3 million, and a long-term lease liability of $0.6 million and no cumulative effect adjustment was made to the retained earnings as of the adoption date. The Company also elected the package of practical expedients under the transition guidance that will retain the historical lease classification and initial direct costs for any leases that exist prior to adoption of the new guidance and the practical expedient to not separate lease and nonlease components. See Note 5 for further disclosure. In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480), Derivatives and Hedging (Topic 815) I. Accounting for Certain Financial Instruments with Down Round Features II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception (“ASU 2017-11”). Part I applies to entities that issue financial instruments such as warrants, convertible debt or redeemable convertible preferred stock that contain down-round features. Part II replaces the indefinite deferral for certain mandatorily redeemable noncontrolling interests and mandatorily redeemable financial instruments of nonpublic entities contained within ASC Topic 480 with a scope exception and does not impact the accounting for these mandatorily redeemable instruments. For public entities, ASU 2017-11 is required to be adopted for annual periods beginning after December 15, 2018, including interim periods within those fiscal years. The adoption of ASU 2017-11 did not have any impact on the Company’s financial statements since the Company did not have any instruments subject to the scope of the ASU. Recent accounting pronouncements not yet adopted The following are new accounting pronouncements that the Company is evaluating for future impacts on its financial statements: Fair Value Measurement—Disclosure Framework: In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement. The new guidance changes disclosure requirements related to fair value measurements as part of the disclosure framework project. The disclosure framework project aims to improve the effectiveness of disclosures in the notes to the financial statements by focusing on requirements that clearly communicate the most important information to users of the financial statements. This guidance is effective for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is evaluating the provisions of the updated guidance and assessing the impact on its financial statements. Financial Instruments—Credit Losses: In June 2016, the FASB issued new guidance which amends the principles around the recognition of credit losses by mandating entities incorporate an estimate of current expected credit losses when determining the value of certain assets. The guidance also amends reporting around allowances for credit losses on available-for-sale marketable securities. This guidance is effective for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is evaluating the provisions of the updated guidance and assessing the impact on its financial statements. In August 2018, the FASB issued Accounting Standards Update No. 2018-15, Intangibles – Goodwill and other – Internal-Use Software (Subtopic 350-40), which amended its guidance for costs of implementing a cloud computing service arrangement and aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software. This new standard also requires customers to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement. The guidance is effective for fiscal years beginning after December 15, 2019, with early adoption permitted. The Company is evaluating the impact of adopting this amendment to its financial statements.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Schedule of Reconciliation of Cash, Cash Equivalents, and Restricted Cash	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the condensed balance sheets that sum to the total of the same amounts shown in the condensed statements of cash flows (in thousands): Three Months Ended March 31, 2019 2018 Cash and cash equivalents $ 20,634 $ 4,404 Restricted cash 250 50 Total cash, cash equivalents and restricted cash $ 20,884 $ 4,454

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of Financial Assets and Liabilities to Fair Value Measurements on Recurring Basis	Financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used in such measurements by major security type as of March 31, 2019 and December 31, 2018 are presented in the following tables (in thousands): Fair Value Measurements at March 31, 2019 Fair Value Hierarchy Amortized Cost Unrealized Gains Unrealized Losses Fair Value Money market funds Level 1 $ 3,565 $ — $ — $ 3,565 Certificates of Deposit Level 2 11,025 1 (2 ) 11,024 Repurchase Agreements Level 2 12,000 — — 12,000 Commercial paper Level 2 5,388 — — 5,388 Corporate notes Level 2 8,386 — (1 ) 8,385 U.S. government notes Level 2 12,588 1 (5 ) 12,584 Asset backed securities Level 2 7,443 3 (20 ) 7,426 Total cash equivalents and investments $ 60,395 $ 5 $ (28 ) $ 60,372 Classified as: Cash equivalents $ 16,546 Short-term investments 38,410 Long-term investments 5,416 Total cash equivalents and investments $ 60,372 Fair Value Measurements at December 31, 2018 Fair Value Hierarchy Amortized Cost Unrealized Gains Unrealized Losses Fair Value Money market funds Level 1 $ 11,815 $ — $ — $ 11,815 Commercial paper Level 2 14,362 — (2 ) 14,360 Corporate notes Level 2 16,129 — (18 ) 16,111 U.S. government notes Level 2 8,980 — (1 ) 8,979 Asset backed securities Level 2 9,220 — (28 ) 9,192 Total cash equivalents and investments $ 60,506 $ — $ (49 ) $ 60,457 Classified as: Cash equivalents $ 13,613 Short-term investments 46,844 Total cash equivalents and investments $ 60,457

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2019
Balance Sheet Components [Abstract]
Schedule of Prepaid Expenses and Other Current Assets	Prepaid expenses and Other Current Assets consist of the following (in thousands): March 31, December 31, 2019 2018 Prepaid expenses $ 243 $ 13 Deferred issuance costs 1,128 34 Prepaid clinical trial expenses 2,678 587 Prepaid research and development expenses 60 166 Other assets 387 68 Total prepaid expenses and other current assets $ 4,496 $ 868
Schedule of Property and Equipment	Property and Equipment consist of the following (in thousands): March 31, December 31, 2019 2018 Lab Equipment $ 428 $ 378 Less: accumulated depreciation (114 ) (95 ) Property and equipment, net $ 314 $ 283
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): March 31, December 31, 2019 2018 Personnel expenses $ 182 $ 483 Professional fees 385 75 Research and development expenses 1,136 380 Other 21 24 Total accrued liabilities $ 1,724 $ 962

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Summary of Maturities on Lease Liabilities	Maturities of the lease liabilities as of March 31, 2019 are presented in the following table (in thousands): Year: 2019 (excluding the three months ended March 31, 2019) $ 275 2020 366 2021 214 Total liabilities 855 Less imputed interest (40 ) Total $ 815 Reported as: Operating lease liabilities $ 340 Operating lease liabilities, net of current portion 475 Total lease liability $ 815

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Stock Options Activity	Number of Options and Unvested Shares Weighted Average Exercise Price Weighted average remaining contractual life (years) Aggregate intrinsic value Balance at December 31, 2018 1,885,504 1.57 9.07 1,252,496 Options granted 397,055 6.91 9.87 Options exercised (154,557 ) 0.41 Options cancelled (66,180 ) 2.23 Balance at March 31, 2019 2,061,822 2.66 9.20 8,759,422 Options vested and expected to vest as of March 31, 2019 2,061,822 2.66 9.20 8,759,422 Options exercisable as of March 31, 2019 1,003,660 0.82 8.05 6,114,427

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Schedule of Outstanding Potentially Dilutive Ordinary Shares Excluded from Calculation of Diluted Net Loss Per Share	The following outstanding potentially dilutive shares have been excluded from the calculation of diluted net loss per share for the period presented due to their anti-dilutive effect: March 31, 2019 2018 Series A redeemable convertible preferred stock 9,008,919 9,008,919 Series B redeemable convertible preferred stock 9,152,108 — Warrants 27,941 27,941 Options issued and outstanding 2,061,822 879,696 Total 20,250,790 9,916,556

Organization - Additional Infor

Organization - Additional Information (Details) $ / shares in Units, $ in Thousands	May 13, 2019USD ($)$ / sharesshares	Apr. 25, 2019	May 31, 2019USD ($)$ / sharesshares	Mar. 31, 2019USD ($)	Dec. 31, 2018USD ($)
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Entity incorporation date				2012-06
Accumulated deficit | $				$ (38,506)	$ (32,825)
Cash, cash equivalents, and short-term investments | $				59,000
Prepaid Expenses and Other Current Assets
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Deferred offering costs | $				$ 1,100
Subsequent Event
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Description of reverse stock split		one-for-0.367647
Reverse stock split		0.367647
Subsequent Event | IPO
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Issuance of stock (in shares) | shares	5,073,800		5,073,800
Public offering price per share | $ / shares	$ 17		$ 17
Proceeds from issuance of common stock, net of underwriting discounts and commissions and offering expenses | $	$ 78,100		$ 78,100
Conversion of redeemable convertible preferred stock to common stock | shares	18,161,027		18,161,027
Redeemable convertible preferred stock, shares outstanding | shares	0		0
Subsequent Event | Underwriters
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Issuance of stock (in shares) | shares	661,800		661,800

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Jan. 01, 2019
Summary Of Significant Accounting Policies [Line Items]
Right-of-use asset	$ 815,000
Short-term lease liability	340,000
Long-term lease liability	475,000
Accounting Standards Update 2016-02
Summary Of Significant Accounting Policies [Line Items]
Right-of-use asset		$ 900,000
Short-term lease liability		300,000
Long-term lease liability		600,000
Cumulative effect adjustment		$ 0
Money Market Funds
Summary Of Significant Accounting Policies [Line Items]
Unrealized gains or loss	$ 0

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents, and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	$ 20,634	$ 24,872	$ 4,404
Restricted cash	250		50
Total cash, cash equivalents and restricted cash	$ 20,884	$ 24,872	$ 4,454	$ 7,393

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 60,395	$ 60,506
Unrealized Gains	5
Unrealized Losses	(28)	(49)
Fair Value	60,372	60,457
Cash equivalents	16,546	13,613
Short term investments	38,410	46,844
Long term investments	5,416
Total cash equivalents and investments	60,372	60,457
Money Market Funds | Level 1
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	3,565	11,815
Fair Value	3,565	11,815
Certificates of Deposit | Level 2
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	11,025
Unrealized Gains	1
Unrealized Losses	(2)
Fair Value	11,024
Repurchase Agreements | Level 2
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	12,000
Fair Value	12,000
Commercial Paper | Level 2
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	5,388	14,362
Unrealized Losses		(2)
Fair Value	5,388	14,360
Corporate Notes | Level 2
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	8,386	16,129
Unrealized Losses	(1)	(18)
Fair Value	8,385	16,111
U.S. government notes | Level 2
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	12,588	8,980
Unrealized Gains	1
Unrealized Losses	(5)	(1)
Fair Value	12,584	8,979
Asset Backed Securities | Level 2
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	7,443	9,220
Unrealized Gains	3
Unrealized Losses	(20)	(28)
Fair Value	$ 7,426	$ 9,192

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair value assets level 1 to level 2	$ 0	$ 0
Fair value assets level 2 to level 1	0	0
Fair value assets transfers into level 3	0	0
Fair value assets transfers out of level 3	$ 0	$ 0

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Prepaid Expense And Other Assets Current [Abstract]
Prepaid expenses	$ 243	$ 13
Deferred issuance costs	1,128	34
Prepaid clinical trial expenses	2,678	587
Prepaid research and development expenses	60	166
Other assets	387	68
Total prepaid expenses and other current assets	$ 4,496	$ 868

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Abstract]
Lab Equipment	$ 428	$ 378
Less: accumulated depreciation	(114)	(95)
Property and equipment, net	$ 314	$ 283

Balance Sheet Components - Sc_3

Balance Sheet Components - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Accrued Liabilities Current [Abstract]
Personnel expenses	$ 182	$ 483
Professional fees	385	75
Research and development expenses	1,136	380
Other	21	24
Total accrued liabilities	$ 1,724	$ 962

Leases - Additional Information

Leases - Additional Information (Details)	1 Months Ended	3 Months Ended
	Jun. 30, 2018USD ($)ft²Investorshares	Mar. 31, 2019USD ($)shares	Dec. 31, 2018shares	Jul. 16, 2018
Lessee Lease Description [Line Items]
Lease agreement period				3 years
Number of investors | Investor	1
Operating lease payments	$ 0
Repurchase option percentage	100.00%
Operating leases period	3 years
Unvested shares repurchase option | shares		89,006
Future rent expense		$ 856,000
Operating lease remaining term on a straight-line basis		28 months
Operating lease discount rate percent		4.00%
Operating lease discount rate term		2 years 4 months 24 days
Non-cash rent expense		$ 92,000
Series B Redeemable Convertible Preferred Stock
Lessee Lease Description [Line Items]
Lease agreement period	3 years
Renewal options	false
Area under lease | ft²	3,185
Redeemable convertible preferred stock, shares issued | shares	114,437	9,152,108	9,152,108
Convertible preferred stock, fair value	$ 1,100,000

Leases - Summary of Maturities

Leases - Summary of Maturities on Lease Liabilities (Details) $ in Thousands	Mar. 31, 2019USD ($)
Leases [Abstract]
2019 (excluding the three months ended March 31, 2019)	$ 275
2020	366
2021	214
Total liabilities	855
Less imputed interest	(40)
Total	815
Short-term lease liability	340
Long-term lease liability	$ 475

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Income tax benefits recognized	$ 0
Unrecognized share-based compensation cost	$ 3,155,694
Unrecognized share-based compensation cost expected to be recognized, period	4 years
Employees and Non-Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense related to options granted	$ 190,000
2014 Stock Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for issuance		2,973,736
Purchase price as percentage of fair value per share for stockholders owning more than 10% of shares		110.00%
Stock options, expiration period		10 years
Stock options, expiration period for stockholders owning greater than 10% of shares		5 years
2014 Stock Plan | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Purchase price as percentage of fair value per share		100.00%
Percentage of capital stock owned by individual to trigger increase in share price		10.00%

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - 2014 Stock Plan - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Options and Unvested Shares, beginning balance	1,885,504
Number of Options and Unvested Shares, granted	397,055
Number of Options and Unvested Shares, exercised	(154,557)
Number of Options and Unvested Shares, cancelled	(66,180)
Number of Options and Unvested Shares, ending balance	2,061,822	1,885,504
Number of Options and Unvested Shares, vested and expected to vest	2,061,822
Number of Options and Unvested Shares, exercisable	1,003,660
Weighted Average Exercise Price, beginning balance	$ 1.57
Weighted Average Exercise Price, granted	6.91
Weighted Average Exercise Price, exercised	0.41
Weighted Average Exercise Price, cancelled	2.23
Weighted Average Exercise Price, ending balance	2.66	$ 1.57
Weighted Average Exercise Price, vested and expected to vest	2.66
Weighted Average Exercise Price, exercisable	$ 0.82
Weighted average remaining contractual life	9 years 2 months 12 days	9 years 25 days
Weighted average remaining contractual life, granted	9 years 10 months 13 days
Weighted average remaining contractual life, vested and expected to vest	9 years 2 months 12 days
Weighted average remaining contractual life, exercisable	8 years 18 days
Aggregate intrinsic value	$ 8,759,422	$ 1,252,496
Aggregate intrinsic value, vested and expected to vest	8,759,422
Aggregate intrinsic value, exercisable	$ 6,114,427

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail)	Jul. 16, 2018ft²shares	May 31, 2019shares	Jun. 30, 2014USD ($)	Mar. 31, 2019shares	Jun. 30, 2018
Related Party Transaction [Line Items]
Percentage of royalties payment to stockholders in amount of gross revenues			3.00%
Lease agreement term	3 years
South San Francisco, California
Related Party Transaction [Line Items]
Area of lease office space | ft²	3,185
Series B Redeemable Convertible Preferred Stock
Related Party Transaction [Line Items]
Lease agreement term					3 years
Restricted stock shares issued	114,437
Restricted stock shares vested				9,537
Series B Redeemable Convertible Preferred Stock | IPO | Subsequent Event
Related Party Transaction [Line Items]
Conversion of preferred stock into common stock		82,649
Maximum
Related Party Transaction [Line Items]
Payment of royalties to stockholders | $			$ 1,050,000

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details)	3 Months Ended
	Mar. 31, 2019USD ($)
Income Tax Disclosure [Abstract]
Provision for income taxes	$ 0
Net operaring loss carry forward	$ 28,000,000
Net operating loss carryforward, expiration year	2034

Net Loss Per Share - Schedule o

Net Loss Per Share - Schedule of Outstanding Potentially Dilutive Shares Excluded from Calculation of Diluted Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of earnings per share, amount	20,250,790	9,916,556
Series A Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of earnings per share, amount	9,008,919	9,008,919
Series B Redeemable Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of earnings per share, amount	9,152,108
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of earnings per share, amount	27,941	27,941
Options Issued and Outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from calculation of earnings per share, amount	2,061,822	879,696

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	May 13, 2019	May 07, 2019	Dec. 31, 2018	May 31, 2019	Mar. 31, 2019
Subsequent Event [Line Items]
Common stock, shares outstanding			3,412,366		3,566,923
2019 Plan
Subsequent Event [Line Items]
Percentage of common stock outstanding			4.00%
Common stock, shares outstanding			2,146,354
Subsequent Event | 2019 Plan
Subsequent Event [Line Items]
Common stock reserved for issuance		5,131,549
Maximum period for common stock shares reserved for future issuance		10 years
Subsequent Event | 2019 ESPP
Subsequent Event [Line Items]
Common stock reserved for issuance		268,295
Maximum period for common stock shares reserved for future issuance		10 years
IPO | Subsequent Event
Subsequent Event [Line Items]
Issuance of stock (in shares)	5,073,800			5,073,800
Public offering price per share	$ 17			$ 17
Proceeds from issuance of common stock, net of underwriting discounts and commissions and offering expenses	$ 78.1			$ 78.1
Conversion of redeemable convertible preferred stock to common stock	18,161,027			18,161,027
Redeemable convertible preferred stock, shares outstanding	0			0
Underwriters | Subsequent Event
Subsequent Event [Line Items]
Issuance of stock (in shares)	661,800			661,800