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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2018	Feb. 28, 2019	Jul. 31, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	CRNX
Entity Registrant Name	Crinetics Pharmaceuticals, Inc.
Entity Central Index Key	0001658247
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		24,095,485
Entity Public Float			$ 382.1

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 44,973	$ 14,192
Short-term investments	118,902
Prepaid expenses and other current assets	2,808	973
Total current assets	166,683	15,165
Property and equipment, net	4,232	400
Restricted cash	500
Other long-term assets		33
Total assets	171,415	15,598
Current liabilities:
Accounts payable	1,456	403
Accrued compensation and benefits	2,279	315
Accrued expenses	4,190	179
Total current liabilities	7,925	897
Deferred rent	3,063	20
Unvested stock liability	202	3
Total liabilities	11,190	920
Commitments and contingencies (Note 6)
Convertible preferred stock, $0.001 par; no shares authorized, issued and outstanding at December 31, 2018; 38,350,914 shares authorized, 28,763,179 shares issued and outstanding, liquidation preference of $30,000 at December 31, 2017		29,700
Stockholders’ equity (deficit):
Preferred stock, $0.001 par; 10,000,000 shares authorized, no shares issued or outstanding at December 31, 2018 or 2017
Common stock, $0.001 par; 200,000,000 shares authorized, 24,187,568 shares issued and 24,060,510 shares outstanding at December 31, 2018; 50,500,000 shares authorized, 2,076,171 shares issued and 1,549,575 shares outstanding at December 31, 2017	24	1
Additional paid-in capital	203,520	1,242
Accumulated other comprehensive income	61
Accumulated deficit	(43,380)	(16,265)
Total stockholders’ equity (deficit)	160,225	(15,022)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 171,415	$ 15,598

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	50,500,000
Common stock, shares issued	24,187,568	2,076,171
Common stock, shares outstanding	24,060,510	1,549,575
Convertible Preferred Stock
Temporary equity, par value	$ 0.001	$ 0.001
Temporary equity, shares authorized	0	38,350,914
Temporary equity, shares issued	0	28,763,179
Temporary equity, shares outstanding	0	28,763,179
Temporary equity, liquidation preference		$ 30,000

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Grant revenues	$ 2,428	$ 2,045	$ 589
Type Of Revenue Extensible List	us-gaap:GrantMember	us-gaap:GrantMember	us-gaap:GrantMember
Operating expenses:
Research and development	$ 24,479	$ 9,233	$ 5,100
General and administrative	6,659	1,939	1,533
Total operating expenses	31,138	11,172	6,633
Loss from operations	(28,710)	(9,127)	(6,044)
Other income (expense):
Interest income	1,748	26	37
Interest expense		(8)	(11)
Other expense	(153)	(48)	(1)
Total other income (expense)	1,595	(30)	25
Net loss	(27,115)	(9,157)	(6,019)
Other comprehensive income (loss):
Unrealized gain on investments	61
Comprehensive loss	$ (27,054)	$ (9,157)	$ (6,019)
Net loss per share:
Net loss per share - basic and diluted	$ (2.23)	$ (6.68)	$ (5.96)
Weighted average shares - basic and diluted	12,142	1,371	1,011

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Initial Public Offering	Convertible Preferred Stock	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Common Stock Initial Public Offering	Additional Paid-In Capital	Additional Paid-In Capital Initial Public Offering	Accumulated Other Comprehensive Income	Accumulated Deficit
Temporary equity, Beginning Balance at Dec. 31, 2015			$ 17,740
Temporary equity, Beginning Balance, Shares at Dec. 31, 2015			17,258,000
Beginning Balance at Dec. 31, 2015	$ (463)					$ 1		$ 625			$ (1,089)
Beginning Balance, Shares at Dec. 31, 2015						877,000
Vesting of shares of common stock subject to repurchase	8							8
Vesting of shares of common stock subject to repurchase, shares						287,000
Exercise of common stock options, shares						1,000
Stock-based compensation expense	270							270
Net loss	(6,019)										(6,019)
Ending Balance at Dec. 31, 2016	(6,204)					$ 1		903			(7,108)
Ending Balance, Shares at Dec. 31, 2016						1,165,000
Temporary equity, Ending Balance at Dec. 31, 2016			$ 17,740
Temporary equity, Ending Balance, Shares at Dec. 31, 2016			17,258,000
Temporary equity, Issuance of convertible preferred stock, net of issuance costs				$ 11,960
Temporary equity, Issuance of convertible preferred stock, net of issuance costs, shares				11,505,000
Vesting of shares of common stock subject to repurchase	2							2
Vesting of shares of common stock subject to repurchase, shares						287,000
Exercise of common stock options	66							66
Exercise of common stock options, shares						98,000
Stock-based compensation expense	271							271
Net loss	(9,157)										(9,157)
Ending Balance at Dec. 31, 2017	(15,022)					$ 1		1,242			(16,265)
Ending Balance, Shares at Dec. 31, 2017						1,550,000
Temporary equity, Ending Balance at Dec. 31, 2017	29,700		$ 29,700
Temporary equity, Ending Balance, Shares at Dec. 31, 2017			28,763,179
Temporary equity, Issuance of convertible preferred stock, net of issuance costs					$ 63,275
Temporary equity, Issuance of convertible preferred stock, net of issuance costs, shares					19,641,000
Issuance of common stock		$ 106,472					$ 7		$ 106,465
Issuance of common stock, shares							6,900,000
Conversion of preferred stock into common stock	92,975					$ 15		92,960
Conversion of preferred stock into common stock, shares						14,713,000
Vesting of shares of common stock subject to repurchase	21					$ 1		20
Vesting of shares of common stock subject to repurchase, shares						541,000
Exercise of common stock options	$ 231							231
Exercise of common stock options, shares	479,287					337,000
Issuance of common stock under Employee Stock Purchase Plan	$ 282							282
Issuance of common stock under Employee Stock Purchase Plan, shares						20,000
Stock-based compensation expense	2,320							2,320
Comprehensive income	61									$ 61
Net loss	(27,115)										(27,115)
Ending Balance at Dec. 31, 2018	$ 160,225					$ 24		$ 203,520		$ 61	$ (43,380)
Ending Balance, Shares at Dec. 31, 2018						24,061,000
Temporary equity, Ending Balance, Shares at Dec. 31, 2018			0

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Statement Of Stockholders Equity [Abstract]
Temporary equity convertible preferred stock issuance costs	$ 225	$ 40
Issuance of common stock in initial public offering net of issuance costs	$ 10,829

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities:
Net loss	$ (27,115)	$ (9,157)	$ (6,019)
Reconciliation of net loss to net cash used in operating activities:
Stock-based compensation	2,320	271	270
Depreciation and amortization of property and equipment	471	128	92
Other	(433)
Increase (decrease) in cash resulting from changes in:
Prepaid expenses and other current assets	(1,802)	(783)	(116)
Accounts payable and accrued expenses	7,361	47	300
Deferred rent	(261)	15	5
Net cash used in operating activities	(19,459)	(9,479)	(5,468)
Investing activities:
Purchases of investment securities	(118,399)
Purchases of property and equipment	(1,059)	(304)	(190)
Net cash used in investing activities	(119,458)	(304)	(190)
Financing activities:
Proceeds from issuance of convertible preferred stock, net	63,275	11,969	(5)
Proceeds from issuance of common stock, net	106,472
Proceeds from exercise of stock options	451	66
Repayments of borrowings under long-term debt		(212)	(48)
Net cash provided by/(used in) financing activities	170,198	11,823	(53)
Net change in cash, cash equivalents and restricted cash	31,281	2,040	(5,711)
Cash, cash equivalents and restricted cash - beginning of period	14,192	12,152	17,863
Cash, cash equivalents and restricted cash - end of period	45,473	14,192	12,152
Supplemental disclosure of cash flow information:
Cash paid for interest		8	11
Non-cash financing activity:
Purchase of shares pursuant to Employee Stock Purchase Plan	282
Change in unvested stock liability	21	$ 2	$ 8
Amounts accrued for purchases of property and equipment	42
Tenant improvement allowance	$ 3,304

Organization and Basis of Presentation

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Basis of Presentation

1. ORGANIZATION AND BASIS OF PRESENTATION

Description of Business

Crinetics Pharmaceuticals, Inc. (the “Company”) is a clinical stage pharmaceutical company incorporated in Delaware on November 18, 2008 and based in San Diego, California. The Company is focused on the discovery, development and commercialization of novel therapeutics for rare endocrine diseases and endocrine-related tumors. In January 2017, the Company established a wholly-owned Australian subsidiary, Crinetics Australia Pty Ltd (“CAPL”), in order to conduct various preclinical and clinical activities for its development candidates.

On July 6, 2018, the Company effected a 1-for-3.29 reverse stock split of its common stock. The par value and the authorized shares of the common stock were not adjusted as a result of the reverse stock split. The reverse stock split resulted in an adjustment to the conversion prices of the Company’s Series A and B preferred stock to reflect a proportional decrease in the number of shares of common stock to be issued upon conversion. The accompanying consolidated financial statements and notes to the consolidated financial statements give retroactive effect to the reverse stock split for all periods presented.

Principles of Consolidation and Foreign Currency Transactions

The consolidated financial statements include the accounts of the Company and CAPL. All intercompany accounts and transactions have been eliminated in consolidation. The functional currency of both the Company and CAPL is the U.S. dollar. The Company’s assets and liabilities that are not denominated in the functional currency are remeasured into U.S. dollars at foreign currency exchange rates in effect at the balance sheet date except for nonmonetary assets, which are remeasured at historical foreign currency exchange rates in effect at the date of transaction. Net realized and unrealized gains and losses from foreign currency transactions and remeasurement are reported in other income (expense), in the consolidated statements of operations and were not material for all periods presented.

Segment Reporting

Operating segments are identified as components of an enterprise about which discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one operating segment.

Liquidity and Going Concern

From inception, the Company has devoted substantially all of its efforts to drug discovery and development and conducting preclinical studies and clinical trials. The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. Successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure.

As of December 31, 2018, the Company had $163.9 million in cash, cash equivalents and short-term investments. The Company believes it has sufficient cash to meet its funding requirements for at least the next 12 months. However, the Company has experienced net losses and negative cash flows from operating activities since its inception and has an accumulated deficit of $43.4 million as of December 31, 2018. The Company expects to continue to incur net losses for the foreseeable future and believes it will need to raise substantial additional capital to accomplish its business plan over the next several years. The Company plans to continue to fund its losses from operations and capital funding needs through a combination of equity offerings, debt financings or other sources, including potentially collaborations, licenses and other similar arrangements. If the Company is not able to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations and future prospects. There can be no assurance as to the availability or terms upon which such financing and capital might be available in the future.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Use of Estimates

The Company’s consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”). The preparation of the Company’s consolidated financial statements requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company’s consolidated financial statements and accompanying notes. The most significant estimates in the Company’s consolidated financial statements relate to revenue recognition, accrued amounts receivable under the Australian research and development tax incentive program, accrued expenses and associated research and development expense, and the assumptions underlying the determination of the fair value of equity awards for purposes of determining stock-based compensation. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.

Fair Value Measurements

The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or non-recurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows:

Level 1: Observable inputs such as quoted prices in active markets.

Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly.

Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.

The carrying amounts of the Company’s current financial assets, restricted cash and current financial liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments.

Cash, Cash Equivalents and Restricted Cash

The Company considers all highly liquid investments with maturities of three months or less when purchased to be cash equivalents. Cash and cash equivalents include cash in readily available checking and money market accounts. Restricted cash represents cash held as collateral for the Company’s facility lease and is reported as a long-term asset in the accompanying consolidated balance sheets.

Short Term Investments

All investments have been classified as “available-for-sale” and are carried at fair value as determined based upon quoted market prices or pricing models for similar securities at period end. Investments with contractual maturities less than 12 months at the balance sheet date are considered short-term investments. Investments with contractual maturities beyond one year are also classified as short-term due to the Company’s ability to liquidate the investment for use in operations within the next 12 months.

Unrealized gains and losses, deemed temporary in nature, are reported as a component of accumulated other comprehensive income (loss). A decline in the fair value of any security below cost that is deemed other than temporary results in a charge to earnings and the corresponding establishment of a new cost basis for the security. Dividend and interest income are recognized when earned. Realized gains and losses are included in earnings and are derived using the specific identification method for determining the cost of securities sold. The Company has not realized any significant gains or losses on sales of available-for-sale investment securities during any of the periods presented. Amortization of premiums, accretion of discounts, interest, and dividend income are included in investment income.

Concentrations of Credit Risk

Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and investments. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash balances due to the financial position of the depository institution in which those deposits are held. Additionally, the Company has established guidelines regarding approved investments and maturities of investments, which are designed to maintain safety and liquidity.

Property and Equipment, Net

Property and equipment, which consist of lab equipment, and computer, software and office equipment, are stated at cost and depreciated on a straight-line basis over the estimated useful life of the related assets (generally three to five years). Leasehold improvements are stated at cost and amortized on a straight-line basis over the lesser of the remaining lease term of the related lease or the estimated useful life of the leasehold improvements.

Repairs and maintenance costs are charged to expense as incurred and expenditures that materially extend the useful lives of assets are capitalized.

Impairment of Long-Lived Assets

Long-lived assets consist of property and equipment. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. The Company has not recognized any impairment losses through December 31, 2018.

Deferred Rent

Rent expense is recorded on a straight-line basis over the term of the Company’s facility lease. The difference between rent expense and amounts paid under the lease are recorded as deferred rent in the accompanying consolidated balance sheets. When an operating lease includes lease incentives, such as a rent abatements or leasehold improvement allowances, or requires fixed escalations of the minimum lease payments, the aggregate rental expense, including such incentives or increases, is recognized on a straight-line basis over the term of the lease.

Revenue Recognition

The Company’s grant revenues are derived from Small Business Innovation Research Grants (“SBIR Grants”) from the National Institutes of Health. The Company recognizes SBIR Grant revenue as reimbursable grant costs are incurred up to pre-approved award limits within the budget period. The costs associated with these reimbursements are reflected as a component of research and development expense in the accompanying consolidated statements of operations. Earnings in excess of billings are included as a component of prepaid and other current assets.

Research and Development Expenses

Research and development expenses consist primarily of salaries, payroll taxes, employee benefits and stock-based compensation charges for those individuals involved in research and development efforts, as well as consulting expenses, third-party research and development expenses, laboratory supplies, clinical materials and overhead, including facilities and depreciation costs, offset by the Australian Research and Development Tax Incentive (“Australian Tax Incentive”) discussed below. Research and development expenses are charged to expense as incurred. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods or services are received.

Costs incurred under contracts with contract research organizations (CROs) that conduct and manage the Company’s clinical trials are also included in research and development expenses. The financial terms and activities of these agreements vary from contract to contract and may result in uneven expense levels. Generally, these agreements set forth activities that drive the recording of expenses such as start-up and initiation activities, enrollment and treatment of patients, or the completion of other clinical trial activities. Expenses related to clinical trials are accrued based on estimates and/or representations from service providers regarding work performed, including actual level of patient enrollment, completion of patient studies and progress of the clinical trials. Other incidental costs related to patient enrollment or treatment are accrued when reasonably certain. If the amounts that the Company is obligated to pay under its clinical trial agreements are modified (for instance, as a result of changes in the clinical trial protocol or scope of work to be performed), the Company adjusts its accruals accordingly on a prospective basis. Revisions to contractual payment obligations are charged to expense in the period in which the facts that give rise to the revision become reasonably certain.

Australian Research and Development Tax Incentive

CAPL is eligible to obtain a cash refund from the Australian Taxation Office for eligible research and development expenditures under the Australian Research and Development Tax Incentive Program (the “Australian Tax Incentive”). The Australian Tax Incentive is recognized as a reduction to research and development expense when there is reasonable assurance that the Australian Tax Incentive will be received, the relevant expenditure has been incurred, and the amount can be reliably measured. The Company recognized reductions to research and development expense of $1.2 million, $0.5 million and $0 for the years ended December 31, 2018, 2017 and 2016, respectively.

Stock-Based Compensation

Stock-based compensation expense represents the cost of the grant date fair value of employee awards over the requisite service period of the awards (usually the vesting period) on a straight-line basis. For stock awards for which vesting is subject to performance-based milestones, the expense is recorded over the remaining service period after the point when the achievement of the milestone is probable, or the performance condition has been achieved. The Company accounts for awards to nonemployees using the fair value method. Awards to nonemployees are subject to periodic revaluation over their vesting terms. The Company estimates the fair value of all stock option grants using the Black-Scholes option pricing model and recognizes forfeitures as they occur.

Income Taxes

The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date.

The Company recognizes net deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes.

The Company records uncertain tax positions on the basis of a two-step process whereby (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority. The Company recognizes interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability.

Comprehensive Loss

Comprehensive loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. Comprehensive gain (loss) consists of unrealized gains on the Company’s investment securities.

Net Loss Per Share

Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. Dilutive common stock equivalents are comprised of convertible preferred stock, common stock subject to repurchase, and options outstanding under the Company’s stock option plan. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding as inclusion of the potentially dilutive securities would be antidilutive.

Recent Accounting Pronouncements

In February 2016, the FASB established Topic 842, Leases, by issuing Accounting Standards Update (“ASU”) No. 2016-02 (“ASU 2016-02”), which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. ASU 2016-02 establishes a right-of-use model (“ROU”) that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. ASU 2016-02 is effective for the Company on January 1, 2019, and the Company will adopt the standard retrospectively at the beginning of the period of adoption through a cumulative effect adjustment. The new standard provides a number of optional practical expedients in transition. The Company expects to elect the ‘package of practical expedients,’ which permits the Company not to reassess, under ASU 2016-02, our prior conclusions about lease identification, lease classification and initial direct costs. The Company also currently expects to elect the practical expedient to not separate lease and non-lease components of leases of real estate as an accounting policy. The Company expects ASU 2016-02 will have a material effect on our financial statements. While it continues to assess all the effects of adoption, the Company currently believes the most significant effects relate to (1) the recognition of new ROU assets and lease liabilities on the balance sheet for real estate operating leases and (2) providing new disclosures about leasing activities. On adoption, the Company currently expects to recognize additional liabilities of approximately $6.2 million, based on the present value of the remaining minimum rental payments under existing operating leases, with corresponding ROU assets of approximately $2.8 million and unamortized lease incentives of approximately $3.4 million. In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases. This ASU is meant to clarify the guidance in ASU No. 2016-02, Leases. This ASU does not change the core principle of the guidance in Topic 842. Instead, the amendments provide clarifying guidance in a few narrow areas. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements. This ASU provides another transition method for entities who have not yet adopted the new leasing standard by allowing entities to initially apply the new standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. In addition, this ASU provides a practical expedient to lessors to not separate non-lease components from the associated lease components similar to the expedient that is afforded to lessees.

In June 2018, the FASB issued ASU 2018-07, “Improvements to Nonemployee Share-Based Payment Accounting,” which supersedes most of the prior accounting guidance on nonemployee share-based payments, and instead aligns it with existing guidance on employee share-based payments in Topic 718, “Compensation – Stock Compensation.” As a result, nonemployee share-based payment transactions will be measured by estimating the fair value of the equity instruments that an entity is obligated to issue, and the measurement date will be consistent with the measurement date for employee share-based payment awards. Probability is to be considered on nonemployee awards with performance conditions. The classification will continue to be subject to the requirements of Topic 718, although cost recognition of nonemployee awards will remain unchanged. This guidance is effective for the fiscal years and interim reporting periods beginning after December 15, 2018 with early adoption permitted, but no earlier than an entity’s adoption date of Topic 606, “Revenue from Contracts with Customers – Income Tax Implications.” The Company is in the process of determining the effects the adoption will have on its consolidated financial statements.

In August 2018, the FASB issued ASU 2018-13, “Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement,” which improves the effectiveness of the disclosures required under ASC 820, “Fair Value Measurements and Disclosures” and modifies the disclosure requirements on fair value measurements, including the consideration of costs and benefits. The new standard is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption is permitted. The Company is currently evaluating the impact of the pending adoption of this new standard on its consolidated financial statements.

Investment Securities

12 Months Ended

Dec. 31, 2018

Investments Debt And Equity Securities [Abstract]

Investment Securities

3. INVESTMENT SECURITIES

The Company reports its available-for-sale investment securities at their estimated fair values based on quoted market prices for identical or similar instruments. Following is a summary of the available-for-sale short-term investments held by the Company as of December 31, 2018 (in thousands):

	As of December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Market Value
Available-for-sale investment securities:
U.S. government and agency obligations	$	42,193	$	72	$	(1	)	$	42,264
Certificates of deposit		5,408		—		—			5,408
Commercial paper		47,686		—		—			47,686
Corporate debt securities		23,554		2		(12	)		23,544
Total	$	118,841	$	74	$	(13	)	$	118,902

All available-for-sale investment securities held at December 31, 2018, had maturity dates of less than 24 months.

None of the Company’s available-for-sale investment securities were in a material unrealized loss position at December 31, 2018. The Company reviewed its investment holdings as of December 31, 2018 and determined that its unrealized losses were not considered to be other-than-temporary based upon (i) the financial strength of the issuing institution and (ii) the fact that no securities have been in an unrealized loss position for twelve months or more. As such, the Company has not recognized any impairment in its financial statements related to its available-for-sale investment securities.

Fair Value Measurements

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. FAIR VALUE MEASUREMENTS

The Company holds investment securities that consist of highly liquid, investment grade debt securities. The Company determines the fair value of its investment securities based upon one or more valuations reported by its investment accounting and reporting service provider. The investment service provider values the securities using a hierarchical security pricing model that relies primarily on valuations provided by an industry-recognized valuation service. Such valuations may be based on trade prices in active markets for identical assets or liabilities (Level 1 inputs) or valuation models using inputs that are observable either directly or indirectly (Level 2 inputs), such as quoted prices for similar assets or liabilities, yield curves, volatility factors, credit spreads, default rates, loss severity, current market and contractual prices for the underlying instruments or debt, and broker and dealer quotes, as well as other relevant economic measures.

Financial assets measured at fair value on a recurring basis as of December 31, 2018 were as follows (in thousands):

	As of December 31, 2018
	Level 1		Level 2		Level 3		Total
Investment securities:
U.S. government and agency obligations	$	22,275	$	19,989	$	—	$	42,264
Certificates of deposit		—		5,408		—		5,408
Commercial paper		—		47,686		—		47,686
Corporate debt securities		—		23,544		—		23,544
Total assets measured at fair value	$	22,275	$	96,627	$	—	$	118,902

The Company’s policy is to recognize transfers between levels of the fair value hierarchy on the date of the event or change in circumstances that caused the transfer. There were no transfers into or out of Level 3 during the year ended December 31, 2018.

As of December 31, 2017, the Company had no financial assets measured at fair value on a recurring basis and none of the Company’s non-financial assets and liabilities were recorded at fair value on a non-recurring basis.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Details

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Balance Sheet Details

5. BALANCE SHEET DETAILS

Prepaid expenses and other current assets consist of the following (in thousands):

	December 31, 2018		December 31, 2017
SBIR grant receivable	$	568	$	231
Australian tax incentive receivable		1,016		503
Prepaid expenses and other assets		1,224		239
Total	$	2,808	$	973

Property and equipment consist of the following (in thousands):

	December 31, 2018			December 31, 2017
Leasehold improvements	$	3,494		$	18
Laboratory equipment		915			640
Office equipment		523			19
Computers and software		41			27
Property and equipment at cost		4,973			704
Accumulated depreciation and amortization		(741	)		(304	)
Total	$	4,232		$	400

Accrued expenses consist of the following (in thousands):

	December 31, 2018		December 31, 2017
Accrued research and development costs	$	3,634	$	126
Deferred rent		381		—
Other accrued expenses		175		53
Total	$	4,190	$	179

Commitments and Contingencies

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

6. COMMITMENTS AND CONTINGENCIES

Operating Leases

2018 Operating Lease. In February 2018, as amended in March 2018, the Company entered into a non-cancelable operating lease for a new facility in San Diego, California. The lease has an initial term of seven years and the Company has an option to extend the term of the lease for an additional five years and has a termination option subject to early termination fees. The lease is subject to base lease payments and additional charges for common area maintenance and other costs and includes certain lease incentives and tenant improvement allowances. Under the terms of the lease, the Company provided the lessor with an irrevocable letter of credit in the amount of $0.5 million. The lessor is entitled to draw on the letter of credit in the event of any default by the Company under the terms of the lease.

Rent expense is being recognized on a straight-line basis over the term of the lease. Rent expense was $0.6 million, $0.2 million and $0.1 million for the years ended December 31, 2018, 2017 and 2016, respectively.

Future Minimum Payments. As of December 31, 2018, future minimum payments under non-cancellable operating leases were as follows (in thousands):

Year ending December 31,	Minimum Payments
2019	$	1,058
2020		1,123
2021		1,173
2022		1,208
2023		1,244
Thereafter		2,151
Total	$	7,957

Litigation

From time to time, the Company may be subject to various claims and suits arising in the ordinary course of business. The Company does not expect that the resolution of these matters will have a material adverse effect on its financial position or results of operations.

Convertible Preferred Stock

12 Months Ended

Dec. 31, 2018

Temporary Equity Disclosure [Abstract]

Convertible Preferred Stock

7. CONVERTIBLE PREFERRED STOCK

In February and March 2018, the Company issued an aggregate of 19,641,200 shares of its Series B convertible preferred stock for gross proceeds of $63.5 million, net of issuance costs incurred in connection with this offering of $0.2 million.

In April and December 2017, pursuant to a Series A preferred stock purchase agreement entered into in October 2015 which called for an initial closing and, upon the achievement of certain specified milestones, subsequent closings, the Company issued an aggregate of 11,505,268 shares of Series A convertible preferred stock for gross proceeds of $12.0 million, net of offering costs of $40,000.

The holders of the convertible preferred stock were entitled to certain customary preferences, such as dividend and liquidation priority in relationship to the common shareholders, and certain anti-dilution protection. The convertible preferred stock was classified outside of stockholders’ equity (deficit) because the shares contained certain redemption features that were not solely within the control of the Company. In connection with the Company’s initial public offering, the outstanding shares of the Company’s Series A and Series B convertible preferred stock automatically converted into 14,712,571 shares of common stock (see Note 8).

Stockholders Equity

12 Months Ended

Dec. 31, 2018

Equity [Abstract]

Stockholders Equity

8. STOCKHOLDERS’ EQUITY

Initial Public Offering

On July 20, 2018, the Company completed its initial public offering (“IPO”) whereby it sold 6,900,000 shares of common stock at a price to the public of $17.00 per share. Proceeds from the IPO were approximately $106.5 million, net of underwriting discounts and commissions and offering costs. In addition, an amended and restated certificate of incorporation was filed by the Company on July 20, 2018, authorizing 200,000,000 shares of common stock and 10,000,000 shares of undesignated preferred stock.

Shares of Common Stock Subject to Repurchase

In October 2015, in connection with the issuance of the Company’s Series A convertible preferred stock, certain of the Company’s founders entered into stock restriction agreements, whereby 1,914,893 of previously unrestricted shares of common stock became subject to repurchase by the Company upon the stockholder’s termination of employment or service to the Company. The Company’s repurchase rights lapsed as to 765,957 shares of common stock in October 2015, with the remainder scheduled to lapse at the rate of 23,936 shares monthly thereafter such that the shares of common stock would have been fully vested in October 2019. Under the terms of the stock restriction agreements, the shares of common stock were also subject to accelerated vesting upon certain events, such that all of these restricted shares became fully vested upon the closing of the Company’s Series B preferred stock financing in February 2018. The stock restriction agreements resulted in the deemed cancellation and reissuance of shares of common stock and therefore, for accounting purposes, the shares subject to repurchase were not considered to be outstanding until vested. The fair value of these shares of $1.4 million as of October 2015 was recognized as compensation expense over the vesting period.

For the years ended December 31, 2018, 2017 and 2016, the Company recognized stock-based compensation for these awards of $0.4 million, $0.2 million and $0.2 million, respectively.

Equity Incentive Plans

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Equity Incentive Plans

9. EQUITY INCENTIVE PLANS

2018 Incentive Award Plan

In July 2018, the Company adopted the 2018 Incentive Award Plan (the “2018 Plan”). Under the 2018 Plan, which expires in July 2028, the Company may grant equity-based awards to individuals who are employees, officers, directors or consultants of the Company. At adoption, a total of 1,991,636 shares of common stock were available for issuance under the 2018 Plan, which number includes the number of shares available for future issuance under the 2015 Plan as of the effective date of the 2018 Plan. Options issued under the 2018 Plan will generally expire ten years from the date of grant and vest over a four-year period.

The 2018 Plan contains an “evergreen provision” that allows annual increases in the number of shares available for issuance on the first day of each calendar year through January 1, 2028 in an amount equal to the lesser of: (i) 5% of the outstanding capital stock on each January 1, or (ii) such lesser amount determined by the Company. As of December 31, 2018, an aggregate of 1,855,396 shares of common stock were available for issuance under the 2018 Plan. Under the evergreen provision, on January 1, 2019, an additional 1,209,378 shares became available for issuance under the 2018 Plan.

2015 Stock Incentive Plan

In February 2015, the Company adopted the Crinetics Pharmaceuticals, Inc. 2015 Stock Incentive Plan (the “2015 Plan”), which provided for the issuance of equity awards to the Company’s employees, members of its board of directors and consultants. In general, options issued under this plan vest over four years and expire after 10 years. Subsequent to the adoption of the 2018 Plan, no additional equity awards can be made under the 2015 Plan.

Certain of the awards issued under the 2015 Plan allowed for exercise prior to vesting. Shares issued under such early-exercise provisions are subject to repurchase by the Company until they become fully vested. As of December 31, 2018, 127,058 unvested shares issued under early-exercise provisions were subject to repurchase by the Company. The consolidated balance sheet reflects an unvested stock liability of $0.2 million as of December 31, 2018.

2018 Employee Stock Purchase Plan

In July 2018, the Company’s board of directors and stockholders approved and adopted the 2018 Employee Stock Purchase Plan (the “ESPP”). The ESPP became effective on the day prior to the effectiveness of the IPO. The ESPP permits participants to purchase common stock through payroll deductions of up to 20% of their eligible compensation. A total of 250,000 shares of common stock were approved to be initially reserved for issuance under the ESPP.

The ESPP contains an “evergreen provision” that allows annual increases in the number of shares available for issuance on the first day of each calendar year through January 1, 2028 in an amount equal to the lesser of: (i) 1% of the outstanding capital stock on each January 1, or (ii) such lesser amount determined by the Company. As of December 31, 2018, an aggregate of 230,461 shares of common stock were available for issuance under the ESPP. Under the evergreen provision, on January 1, 2019, an additional 241,875 shares became available for issuance under the plan.

Stock Options

A summary of the 2018 activity (and related information) under both the 2018 Plan and the 2015 Plan follows:

				Weighted-		Weighted-		Aggregate
				Average		Average		Intrinsic
	Options			Exercise		Remaining		Value
	Outstanding			Price		Term		(000’s)
Balance at December 31, 2017		838,276		$	0.80
Granted		2,002,332		$	7.37
Exercised		(479,287	)	$	0.94			$	2,403
Forfeited and expired		(22,164	)	$	0.91
Balance at December 31, 2018		2,339,157		$	6.40		9.0	$	55,257
Exercisable at December 31, 2018		250,090		$	4.54		8.1	$	6,366

Fair Value of Stock Option Awards

The Company uses the Black-Scholes option pricing model to value awards under its equity plans. The following table summarizes the weighted average assumptions used to estimate the fair value of stock options granted to employees under the Company’s stock option plans and the shares purchasable under the ESPP during the periods presented:

	Year ended December 31,
Employee Stock Options	2018			2017			2016
Expected life of option	6.0 years			6.0 years			6.1 years
Volatility		70	%		71	%		64	%
Risk free interest rate		2.8	%		2.1	%		1.5	%
Dividend yield		—	%		—	%		—	%

	Year ended December 31,
Employee Stock Purchase Plan	2018			2017	2016
Expected life of option	1.1 years			N/A	N/A
Volatility		66	%	N/A	N/A
Risk free interest rate		2.4	%	N/A	N/A
Dividend yield		—	%	N/A	N/A

The key assumptions used in determining the fair value of equity awards, and the Company’s rationale, were as follows:

•

Expected term. The expected term represents the period that options are expected to be outstanding. As the Company does not have significant historical exercise behavior, it determines the expected life assumption using the simplified method, which is an average of the contractual option term and its vesting period.

•

Expected volatility. As the Company’s common stock does not have a significant trading history, the expected volatility assumption is based on volatilities of a peer group of similar companies in the biotechnology industry whose share prices are publicly available. The Company will continue to apply this process until sufficient historical information regarding the volatility of its own stock price is available.

•

Risk-free interest rate. The risk-free interest rate is based on the U.S. Treasury yield in effect at the time of grant for zero coupon U.S. Treasury notes with maturities that approximate the expected terms of awards.

•

Expected dividend yield. The Company bases the expected dividend yield assumption on the fact that it has never paid cash dividends and has no present intention to pay cash dividends, and therefore, the Company used an expected dividend yield of zero.

The weighted-average fair value of stock options granted to employees during the three years ended December 31, 2018, 2017 and 2016 was $4.66, $0.85 and $0.43 per share, respectively.

Stock-Based Compensation Expense

The following table summarizes stock-based compensation expense for the equity awards issued by the Company to employees and non-employees for the periods presented (in thousands):

	Year ended December 31,
	2018		2017		2016
Included in research and development	$	1,100	$	122	$	108
Included in general and administrative		1,220		149		162
Total stock-based compensation expense	$	2,320	$	271	$	270

Unrecognized stock-based compensation cost related to employee option awards was $7.9 million as of December 31, 2018, which is expected to be recognized over a remaining weighted-average period of approximately 3.4 years. Unrecognized stock-based compensation cost related to the ESPP was $0.6 million as of December 31, 2018, which is expected to be recognized over a remaining period of approximately 1.4 years.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

10. INCOME TAXES

The Company is subject to taxation in the United States, California and Australia; however, as it has operated at a loss since inception, it has not paid income taxes in any of the jurisdictions in which it has operated. At December 31, 2018, the Company had federal, state, and foreign net operating loss (“NOL”) carryforwards of approximately $8.7 million, $10.9 million and $0.1 million, respectively. The federal loss carryforwards generated in 2018 will carryforward indefinitely and can be used to offset up to 80% of future annual taxable income, while those loss carryforwards generated prior to 2018 begin expiring in 2035, unless previously utilized. State loss carryforwards begin expiring in 2035, unless previously utilized, while the Company’s foreign loss carryforwards do not expire. The Company also has federal and California research and development (“R&D”) credit carryforwards totaling $1.4 million and $0.9 million, respectively. The federal credits begin to expire in 2030 unless previously utilized, while the state credits do not expire.

Future utilization of the Company’s NOL and R&D credit carryforwards to offset future taxable income may be subject to a substantial annual limitation as a result of ownership changes that may have occurred or that could occur in the future pursuant to Internal Revenue Code Sections 382 and 383. These ownership changes may limit the amount of NOL and R&D credit carryforwards that can be utilized to offset future taxable income and tax, respectively. In general, an “ownership change” as defined by the tax code results from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percent of the outstanding stock of a company by certain stockholders or public groups. The Company has not completed an analysis regarding the limitation of NOL and R&D credit carryforwards.

In December 2017, the Tax Cuts and Jobs Act (the “2017 Act”) was enacted. The 2017 Act included a number of changes to existing U.S. tax laws that impact the Company, most notably a reduction of the U.S. corporate income tax rate from 35 percent to 21 percent for tax years beginning after December 31, 2017. The 2017 Act also provided for a one-time transition tax on certain foreign earnings, the acceleration of depreciation for certain assets placed into service after September 27, 2017 as well as prospective changes beginning in 2018, including repeal of the domestic manufacturing deduction, acceleration of tax revenue recognition, global intangible low taxed income, foreign derived intangible income deduction, additional limitations on executive compensation and limitations on the deductibility of interest. The Company recognized the income tax effects of the 2017 Act in its 2017 financial statements in accordance with Staff Accounting Bulletin No. 118, which provided SEC staff guidance for the application of ASC Topic 740, Income Taxes, in the reporting period in which the 2017 Act was signed into law. As such, the Company’s financial results reflected the income tax effects of the 2017 Act for which the accounting under ASC Topic 740 was complete and provisional amounts for those specific income tax effects of the 2017 Act which were not complete. As of December 31, 2018, the accounting for the income tax effects of the 2017 Act is complete. The effects of the 2017 Act did not have a significant impact in 2018 and are included as part of the overall 2018 provision calculation. As a result of the new law, the Company remeasured its deferred tax assets as of December 31, 2017 based on the rates at which they are expected to reverse in the future, resulting in a reduction of deferred tax assets of $1.6 million (which was offset by a corresponding reduction in the valuation allowance).

The Company is subject to audit by various tax authorities, although no such audits are underway. The Company’s federal income tax returns from 2015 forward, state income tax returns from 2014 forward, and its Australian tax returns beginning in 2017 are subject to examination by tax authorities; however, the Company’s tax attribute carryforwards such as NOLs and R&D credits generated in closed years are also subject to examination and remeasurement.

The Company recognizes interest and penalties related to income tax matters in income tax expense. No such costs were recorded during the three years ended December 31, 2018.

Deferred tax assets and liabilities

The Company’s net deferred tax assets are comprised of the following as of December 31, 2018 and 2017 (in thousands):

	December 31,
	2018			2017
Capitalized research expenses	$	6,355		$	2,127
Net operating loss carryforwards		2,664			1,863
Research and development and other tax credits		1,788			829
Accrued expenses		2,479			38
Fixed assets		(866	)		(22	)
Other, net		157			23
Total deferred tax assets, net		12,577			4,858
Less: valuation allowance		(12,577	)		(4,858	)
Net deferred tax assets	$	—		$	—

Realization of deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Management assesses the available positive and negative evidence to estimate if sufficient future taxable income will be generated to use existing deferred tax assets. Based on the weight of evidence, including a history of operating losses, management has determined that it is more likely than not that the Company’s net deferred tax assets will not be realized. Accordingly, a valuation allowance has been established by the Company to fully offset these net deferred tax assets.

Income tax benefit

Domestic and foreign pre-tax loss were as follows for the three years in the period ended December 31, 2018 (in thousands):

	Year ended December 31,
	2018			2017			2016
Loss before income taxes - Domestic	$	(25,876	)	$	(8,141	)	$	(6,019	)
Loss before income taxes - Foreign		(1,239	)		(1,016	)		—
Loss before income taxes - Consolidated	$	(27,115	)	$	(9,157	)	$	(6,019	)

A reconciliation of income tax expense to the amount computed by applying the statutory federal income tax rate to the loss from operations for the three years in the period ended December 31, 2018 is summarized as follows (in thousands):

	Year ended December 31,
	2018			2017			2016
Expected income tax benefit at federal statutory rate	$	(5,694	)	$	(3,113	)	$	(2,046	)
State income tax benefit, net of federal benefit		(1,758	)		(474	)		(327	)
Tax effect of
Change in valuation allowance		7,724			2,112			2,511
Research and development credit		(1,129	)		(525	)		(342	)
Federal rate change		(52	)		1,602			—
Australian tax incentive		362			176			—
Other		547			222			204
Total	$	—		$	—		$	—

Changes to the Company’s unrecognized tax benefits are summarized in the following table (in thousands):

	Year ended December 31,
	2018		2017		2016
Beginning balance	$	159	$	68	$	—
Increase (decrease) for prior year tax positions		—		—		—
Increase (decrease) for current year tax positions		185		91		68
Ending balance	$	344	$	159	$	68

Due to the existence of the valuation allowance, future changes in unrecognized tax benefits would not have any effect on the Company’s effective tax rate. The Company does not foresee any material changes to its unrecognized tax benefits within the next twelve months.

Net Loss Per Share

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Net Loss Per Share

11. NET LOSS PER SHARE

Potentially dilutive securities (in common stock equivalent shares) not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in thousands):

	Year ended December 31,
	2018		2017		2016
Convertible preferred stock outstanding		—		8,743		5,246
Common stock options		2,339		838		856
Unvested common stock subject to repurchase		127		527		814
Total		2,466		10,108		6,916

Quarterly Data (unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Quarterly Data (unaudited)

12. QUARTERLY DATA (unaudited)

The following quarterly financial data, in the opinion of management, reflects all adjustments, consisting of normal recurring adjustments, necessary for a fair presentation of results for the periods presented (in thousands, except per share amounts):

	Year Ended December 31, 2018
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
Grant revenues	$	442		$	657		$	548		$	781
Research and development expenses	$	4,720		$	5,222		$	6,886		$	7,651
General and administrative expenses	$	1,248		$	1,118		$	1,732		$	2,561
Total operating expenses	$	5,968		$	6,340		$	8,618		$	10,212
Net loss	$	(5,464	)	$	(5,568	)	$	(7,588	)	$	(8,495	)
Net loss per share – basic and diluted	$	(2.92	)	$	(2.41	)	$	(0.38	)	$	(0.35	)

	Year Ended December 31, 2017
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
Grant revenues	$	45		$	832		$	640		$	528
Research and development expenses	$	2,065		$	2,083		$	2,523		$	2,562
General and administrative expenses	$	589		$	392		$	491		$	467
Total operating expenses	$	2,654		$	2,475		$	3,014		$	3,029
Net loss	$	(2,606	)	$	(1,648	)	$	(2,382	)	$	(2,521	)
Net loss per share – basic and diluted	$	(2.18	)	$	(1.22	)	$	(1.67	)	$	(1.68	)

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2018
Accounting Policies [Abstract]
Description of Business	Description of Business Crinetics Pharmaceuticals, Inc. (the “Company”) is a clinical stage pharmaceutical company incorporated in Delaware on November 18, 2008 and based in San Diego, California. The Company is focused on the discovery, development and commercialization of novel therapeutics for rare endocrine diseases and endocrine-related tumors. In January 2017, the Company established a wholly-owned Australian subsidiary, Crinetics Australia Pty Ltd (“CAPL”), in order to conduct various preclinical and clinical activities for its development candidates. On July 6, 2018, the Company effected a 1-for-3.29 reverse stock split of its common stock. The par value and the authorized shares of the common stock were not adjusted as a result of the reverse stock split. The reverse stock split resulted in an adjustment to the conversion prices of the Company’s Series A and B preferred stock to reflect a proportional decrease in the number of shares of common stock to be issued upon conversion. The accompanying consolidated financial statements and notes to the consolidated financial statements give retroactive effect to the reverse stock split for all periods presented.
Principles of Consolidation and Foreign Currency Transactions	Principles of Consolidation and Foreign Currency Transactions The consolidated financial statements include the accounts of the Company and CAPL. All intercompany accounts and transactions have been eliminated in consolidation. The functional currency of both the Company and CAPL is the U.S. dollar. The Company’s assets and liabilities that are not denominated in the functional currency are remeasured into U.S. dollars at foreign currency exchange rates in effect at the balance sheet date except for nonmonetary assets, which are remeasured at historical foreign currency exchange rates in effect at the date of transaction. Net realized and unrealized gains and losses from foreign currency transactions and remeasurement are reported in other income (expense), in the consolidated statements of operations and were not material for all periods presented.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one operating segment.
Liquidity and Going Concern	Liquidity and Going Concern From inception, the Company has devoted substantially all of its efforts to drug discovery and development and conducting preclinical studies and clinical trials. The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. Successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. As of December 31, 2018, the Company had $163.9 million in cash, cash equivalents and short-term investments. The Company believes it has sufficient cash to meet its funding requirements for at least the next 12 months. However, the Company has experienced net losses and negative cash flows from operating activities since its inception and has an accumulated deficit of $43.4 million as of December 31, 2018. The Company expects to continue to incur net losses for the foreseeable future and believes it will need to raise substantial additional capital to accomplish its business plan over the next several years. The Company plans to continue to fund its losses from operations and capital funding needs through a combination of equity offerings, debt financings or other sources, including potentially collaborations, licenses and other similar arrangements. If the Company is not able to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations and future prospects. There can be no assurance as to the availability or terms upon which such financing and capital might be available in the future.
Use of Estimates	Use of Estimates The Company’s consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”). The preparation of the Company’s consolidated financial statements requires it to make estimates and assumptions that impact the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company’s consolidated financial statements and accompanying notes. The most significant estimates in the Company’s consolidated financial statements relate to revenue recognition, accrued amounts receivable under the Australian research and development tax incentive program, accrued expenses and associated research and development expense, and the assumptions underlying the determination of the fair value of equity awards for purposes of determining stock-based compensation. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
Fair Value Measurements	Fair Value Measurements The accounting guidance defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or non-recurring basis. Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets. Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly. Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. The carrying amounts of the Company’s current financial assets, restricted cash and current financial liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments with maturities of three months or less when purchased to be cash equivalents. Cash and cash equivalents include cash in readily available checking and money market accounts. Restricted cash represents cash held as collateral for the Company’s facility lease and is reported as a long-term asset in the accompanying consolidated balance sheets.
Short Term and Long-Term Investments	Short Term Investments All investments have been classified as “available-for-sale” and are carried at fair value as determined based upon quoted market prices or pricing models for similar securities at period end. Investments with contractual maturities less than 12 months at the balance sheet date are considered short-term investments. Investments with contractual maturities beyond one year are also classified as short-term due to the Company’s ability to liquidate the investment for use in operations within the next 12 months. Unrealized gains and losses, deemed temporary in nature, are reported as a component of accumulated other comprehensive income (loss). A decline in the fair value of any security below cost that is deemed other than temporary results in a charge to earnings and the corresponding establishment of a new cost basis for the security. Dividend and interest income are recognized when earned. Realized gains and losses are included in earnings and are derived using the specific identification method for determining the cost of securities sold. The Company has not realized any significant gains or losses on sales of available-for-sale investment securities during any of the periods presented. Amortization of premiums, accretion of discounts, interest, and dividend income are included in investment income.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially subject the Company to significant concentrations of credit risk consist primarily of cash, cash equivalents and investments. The Company maintains deposits in federally insured financial institutions in excess of federally insured limits. The Company has not experienced any losses in such accounts and believes it is not exposed to significant risk on its cash balances due to the financial position of the depository institution in which those deposits are held. Additionally, the Company has established guidelines regarding approved investments and maturities of investments, which are designed to maintain safety and liquidity.
Property and Equipment, Net	Property and Equipment, Net Property and equipment, which consist of lab equipment, and computer, software and office equipment, are stated at cost and depreciated on a straight-line basis over the estimated useful life of the related assets (generally three to five years). Leasehold improvements are stated at cost and amortized on a straight-line basis over the lesser of the remaining lease term of the related lease or the estimated useful life of the leasehold improvements. Repairs and maintenance costs are charged to expense as incurred and expenditures that materially extend the useful lives of assets are capitalized.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. The Company has not recognized any impairment losses through December 31, 2018.
Deferred Rent	Deferred Rent Rent expense is recorded on a straight-line basis over the term of the Company’s facility lease. The difference between rent expense and amounts paid under the lease are recorded as deferred rent in the accompanying consolidated balance sheets. When an operating lease includes lease incentives, such as a rent abatements or leasehold improvement allowances, or requires fixed escalations of the minimum lease payments, the aggregate rental expense, including such incentives or increases, is recognized on a straight-line basis over the term of the lease.
Revenue Recognition	Revenue Recognition The Company’s grant revenues are derived from Small Business Innovation Research Grants (“SBIR Grants”) from the National Institutes of Health. The Company recognizes SBIR Grant revenue as reimbursable grant costs are incurred up to pre-approved award limits within the budget period. The costs associated with these reimbursements are reflected as a component of research and development expense in the accompanying consolidated statements of operations. Earnings in excess of billings are included as a component of prepaid and other current assets.
Research and Development Expenses	Research and Development Expenses Research and development expenses consist primarily of salaries, payroll taxes, employee benefits and stock-based compensation charges for those individuals involved in research and development efforts, as well as consulting expenses, third-party research and development expenses, laboratory supplies, clinical materials and overhead, including facilities and depreciation costs, offset by the Australian Research and Development Tax Incentive (“Australian Tax Incentive”) discussed below. Research and development expenses are charged to expense as incurred. Payments made prior to the receipt of goods or services to be used in research and development are capitalized until the goods or services are received. Costs incurred under contracts with contract research organizations (CROs) that conduct and manage the Company’s clinical trials are also included in research and development expenses. The financial terms and activities of these agreements vary from contract to contract and may result in uneven expense levels. Generally, these agreements set forth activities that drive the recording of expenses such as start-up and initiation activities, enrollment and treatment of patients, or the completion of other clinical trial activities. Expenses related to clinical trials are accrued based on estimates and/or representations from service providers regarding work performed, including actual level of patient enrollment, completion of patient studies and progress of the clinical trials. Other incidental costs related to patient enrollment or treatment are accrued when reasonably certain. If the amounts that the Company is obligated to pay under its clinical trial agreements are modified (for instance, as a result of changes in the clinical trial protocol or scope of work to be performed), the Company adjusts its accruals accordingly on a prospective basis. Revisions to contractual payment obligations are charged to expense in the period in which the facts that give rise to the revision become reasonably certain.
Australian Research and Development Tax Incentive	Australian Research and Development Tax Incentive CAPL is eligible to obtain a cash refund from the Australian Taxation Office for eligible research and development expenditures under the Australian Research and Development Tax Incentive Program (the “Australian Tax Incentive”). The Australian Tax Incentive is recognized as a reduction to research and development expense when there is reasonable assurance that the Australian Tax Incentive will be received, the relevant expenditure has been incurred, and the amount can be reliably measured. The Company recognized reductions to research and development expense of $1.2 million, $0.5 million and $0 for the years ended December 31, 2018, 2017 and 2016, respectively.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation expense represents the cost of the grant date fair value of employee awards over the requisite service period of the awards (usually the vesting period) on a straight-line basis. For stock awards for which vesting is subject to performance-based milestones, the expense is recorded over the remaining service period after the point when the achievement of the milestone is probable, or the performance condition has been achieved. The Company accounts for awards to nonemployees using the fair value method. Awards to nonemployees are subject to periodic revaluation over their vesting terms. The Company estimates the fair value of all stock option grants using the Black-Scholes option pricing model and recognizes forfeitures as they occur.
Income Taxes	Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the consolidated financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the consolidated financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. The Company recognizes net deferred tax assets to the extent that the Company believes these assets are more likely than not to be realized. In making such a determination, management considers all available positive and negative evidence, including future reversals of existing taxable temporary differences, projected future taxable income, tax-planning strategies, and results of recent operations. If management determines that the Company would be able to realize its deferred tax assets in the future in excess of their net recorded amount, management would make an adjustment to the deferred tax asset valuation allowance, which would reduce the provision for income taxes. The Company records uncertain tax positions on the basis of a two-step process whereby (1) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50% likely to be realized upon ultimate settlement with the related tax authority. The Company recognizes interest and penalties related to unrecognized tax benefits within income tax expense. Any accrued interest and penalties are included within the related tax liability.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as a change in equity during a period from transactions and other events and circumstances from non-owner sources. Comprehensive gain (loss) consists of unrealized gains on the Company’s investment securities.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is computed by dividing the net loss by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss by the weighted-average number of shares of common stock and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. Dilutive common stock equivalents are comprised of convertible preferred stock, common stock subject to repurchase, and options outstanding under the Company’s stock option plan. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding as inclusion of the potentially dilutive securities would be antidilutive.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the FASB established Topic 842, Leases, by issuing Accounting Standards Update (“ASU”) No. 2016-02 (“ASU 2016-02”), which requires lessees to recognize leases on-balance sheet and disclose key information about leasing arrangements. ASU 2016-02 establishes a right-of-use model (“ROU”) that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with a term longer than 12 months. ASU 2016-02 is effective for the Company on January 1, 2019, and the Company will adopt the standard retrospectively at the beginning of the period of adoption through a cumulative effect adjustment. The new standard provides a number of optional practical expedients in transition. The Company expects to elect the ‘package of practical expedients,’ which permits the Company not to reassess, under ASU 2016-02, our prior conclusions about lease identification, lease classification and initial direct costs. The Company also currently expects to elect the practical expedient to not separate lease and non-lease components of leases of real estate as an accounting policy. The Company expects ASU 2016-02 will have a material effect on our financial statements. While it continues to assess all the effects of adoption, the Company currently believes the most significant effects relate to (1) the recognition of new ROU assets and lease liabilities on the balance sheet for real estate operating leases and (2) providing new disclosures about leasing activities. On adoption, the Company currently expects to recognize additional liabilities of approximately $6.2 million, based on the present value of the remaining minimum rental payments under existing operating leases, with corresponding ROU assets of approximately $2.8 million and unamortized lease incentives of approximately $3.4 million. In July 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases. This ASU is meant to clarify the guidance in ASU No. 2016-02, Leases. This ASU does not change the core principle of the guidance in Topic 842. Instead, the amendments provide clarifying guidance in a few narrow areas. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements. This ASU provides another transition method for entities who have not yet adopted the new leasing standard by allowing entities to initially apply the new standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. In addition, this ASU provides a practical expedient to lessors to not separate non-lease components from the associated lease components similar to the expedient that is afforded to lessees. In June 2018, the FASB issued ASU 2018-07, “Improvements to Nonemployee Share-Based Payment Accounting,” which supersedes most of the prior accounting guidance on nonemployee share-based payments, and instead aligns it with existing guidance on employee share-based payments in Topic 718, “Compensation – Stock Compensation.” As a result, nonemployee share-based payment transactions will be measured by estimating the fair value of the equity instruments that an entity is obligated to issue, and the measurement date will be consistent with the measurement date for employee share-based payment awards. Probability is to be considered on nonemployee awards with performance conditions. The classification will continue to be subject to the requirements of Topic 718, although cost recognition of nonemployee awards will remain unchanged. This guidance is effective for the fiscal years and interim reporting periods beginning after December 15, 2018 with early adoption permitted, but no earlier than an entity’s adoption date of Topic 606, “Revenue from Contracts with Customers – Income Tax Implications.” The Company is in the process of determining the effects the adoption will have on its consolidated financial statements. In August 2018, the FASB issued ASU 2018-13, “Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement,” which improves the effectiveness of the disclosures required under ASC 820, “Fair Value Measurements and Disclosures” and modifies the disclosure requirements on fair value measurements, including the consideration of costs and benefits. The new standard is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years, and early adoption is permitted. The Company is currently evaluating the impact of the pending adoption of this new standard on its consolidated financial statements.

Investment Securities (Tables)

12 Months Ended

Dec. 31, 2018

Investments Debt And Equity Securities [Abstract]

Summary of Available-For-Sale Short-Term Investments Held by the Company

Following is a summary of the available-for-sale short-term investments held by the Company as of December 31, 2018 (in thousands):

	As of December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Market Value
Available-for-sale investment securities:
U.S. government and agency obligations	$	42,193	$	72	$	(1	)	$	42,264
Certificates of deposit		5,408		—		—			5,408
Commercial paper		47,686		—		—			47,686
Corporate debt securities		23,554		2		(12	)		23,544
Total	$	118,841	$	74	$	(13	)	$	118,902

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Financial Assets Measured at Fair Value on Recurring Basis

Financial assets measured at fair value on a recurring basis as of December 31, 2018 were as follows (in thousands):

	As of December 31, 2018
	Level 1		Level 2		Level 3		Total
Investment securities:
U.S. government and agency obligations	$	22,275	$	19,989	$	—	$	42,264
Certificates of deposit		—		5,408		—		5,408
Commercial paper		—		47,686		—		47,686
Corporate debt securities		—		23,544		—		23,544
Total assets measured at fair value	$	22,275	$	96,627	$	—	$	118,902

Balance Sheet Details (Tables)

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Components of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following (in thousands):

	December 31, 2018		December 31, 2017
SBIR grant receivable	$	568	$	231
Australian tax incentive receivable		1,016		503
Prepaid expenses and other assets		1,224		239
Total	$	2,808	$	973

Components of Property and Equipment

Property and equipment consist of the following (in thousands):

	December 31, 2018			December 31, 2017
Leasehold improvements	$	3,494		$	18
Laboratory equipment		915			640
Office equipment		523			19
Computers and software		41			27
Property and equipment at cost		4,973			704
Accumulated depreciation and amortization		(741	)		(304	)
Total	$	4,232		$	400

Components of Accrued Expenses

Accrued expenses consist of the following (in thousands):

	December 31, 2018		December 31, 2017
Accrued research and development costs	$	3,634	$	126
Deferred rent		381		—
Other accrued expenses		175		53
Total	$	4,190	$	179

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Schedule of Future Minimum Payments Under Non-cancellable Operating Leases

As of December 31, 2018, future minimum payments under non-cancellable operating leases were as follows (in thousands):

Year ending December 31,	Minimum Payments
2019	$	1,058
2020		1,123
2021		1,173
2022		1,208
2023		1,244
Thereafter		2,151
Total	$	7,957

Equity Incentive Plans (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of 2018 Activity (and Related Information) under 2018 and 2015 Plan

A summary of the 2018 activity (and related information) under both the 2018 Plan and the 2015 Plan follows:

				Weighted-		Weighted-		Aggregate
				Average		Average		Intrinsic
	Options			Exercise		Remaining		Value
	Outstanding			Price		Term		(000’s)
Balance at December 31, 2017		838,276		$	0.80
Granted		2,002,332		$	7.37
Exercised		(479,287	)	$	0.94			$	2,403
Forfeited and expired		(22,164	)	$	0.91
Balance at December 31, 2018		2,339,157		$	6.40		9.0	$	55,257
Exercisable at December 31, 2018		250,090		$	4.54		8.1	$	6,366

Summarizes the Weighted Average Assumptions Used to Estimate Fair Value of Stock Options Granted to Employees

The following table summarizes the weighted average assumptions used to estimate the fair value of stock options granted to employees under the Company’s stock option plans and the shares purchasable under the ESPP during the periods presented:

	Year ended December 31,
Employee Stock Options	2018			2017			2016
Expected life of option	6.0 years			6.0 years			6.1 years
Volatility		70	%		71	%		64	%
Risk free interest rate		2.8	%		2.1	%		1.5	%
Dividend yield		—	%		—	%		—	%

	Year ended December 31,
Employee Stock Purchase Plan	2018			2017	2016
Expected life of option	1.1 years			N/A	N/A
Volatility		66	%	N/A	N/A
Risk free interest rate		2.4	%	N/A	N/A
Dividend yield		—	%	N/A	N/A

Summary of Stock-based Compensation Expense for the Equity Awards Issued to Employees and Non-Employees

The following table summarizes stock-based compensation expense for the equity awards issued by the Company to employees and non-employees for the periods presented (in thousands):

	Year ended December 31,
	2018		2017		2016
Included in research and development	$	1,100	$	122	$	108
Included in general and administrative		1,220		149		162
Total stock-based compensation expense	$	2,320	$	271	$	270

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Schedule of Deferred Tax Assets and Liabilities

Deferred tax assets and liabilities

The Company’s net deferred tax assets are comprised of the following as of December 31, 2018 and 2017 (in thousands):

	December 31,
	2018			2017
Capitalized research expenses	$	6,355		$	2,127
Net operating loss carryforwards		2,664			1,863
Research and development and other tax credits		1,788			829
Accrued expenses		2,479			38
Fixed assets		(866	)		(22	)
Other, net		157			23
Total deferred tax assets, net		12,577			4,858
Less: valuation allowance		(12,577	)		(4,858	)
Net deferred tax assets	$	—		$	—

Schedule of Domestic and Foreign Pre-Tax Loss

Income tax benefit

Domestic and foreign pre-tax loss were as follows for the three years in the period ended December 31, 2018 (in thousands):

	Year ended December 31,
	2018			2017			2016
Loss before income taxes - Domestic	$	(25,876	)	$	(8,141	)	$	(6,019	)
Loss before income taxes - Foreign		(1,239	)		(1,016	)		—
Loss before income taxes - Consolidated	$	(27,115	)	$	(9,157	)	$	(6,019	)

Schedule of Reconciliation of Income Tax Expense

	Year ended December 31,
	2018			2017			2016
Expected income tax benefit at federal statutory rate	$	(5,694	)	$	(3,113	)	$	(2,046	)
State income tax benefit, net of federal benefit		(1,758	)		(474	)		(327	)
Tax effect of
Change in valuation allowance		7,724			2,112			2,511
Research and development credit		(1,129	)		(525	)		(342	)
Federal rate change		(52	)		1,602			—
Australian tax incentive		362			176			—
Other		547			222			204
Total	$	—		$	—		$	—

Schedule of Unrecognized Tax Benefits

Changes to the Company’s unrecognized tax benefits are summarized in the following table (in thousands):

	Year ended December 31,
	2018		2017		2016
Beginning balance	$	159	$	68	$	—
Increase (decrease) for prior year tax positions		—		—		—
Increase (decrease) for current year tax positions		185		91		68
Ending balance	$	344	$	159	$	68

Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Schedule of Potentially Dilutive Securities (in Common Stock Equivalent Shares) not Included in Calculation of Diluted Net Loss Per Share

	Year ended December 31,
	2018		2017		2016
Convertible preferred stock outstanding		—		8,743		5,246
Common stock options		2,339		838		856
Unvested common stock subject to repurchase		127		527		814
Total		2,466		10,108		6,916

Quarterly Data (unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Summary of Quarterly Financial Data

	Year Ended December 31, 2018
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
Grant revenues	$	442		$	657		$	548		$	781
Research and development expenses	$	4,720		$	5,222		$	6,886		$	7,651
General and administrative expenses	$	1,248		$	1,118		$	1,732		$	2,561
Total operating expenses	$	5,968		$	6,340		$	8,618		$	10,212
Net loss	$	(5,464	)	$	(5,568	)	$	(7,588	)	$	(8,495	)
Net loss per share – basic and diluted	$	(2.92	)	$	(2.41	)	$	(0.38	)	$	(0.35	)

	Year Ended December 31, 2017
	First Quarter			Second Quarter			Third Quarter			Fourth Quarter
Grant revenues	$	45		$	832		$	640		$	528
Research and development expenses	$	2,065		$	2,083		$	2,523		$	2,562
General and administrative expenses	$	589		$	392		$	491		$	467
Total operating expenses	$	2,654		$	2,475		$	3,014		$	3,029
Net loss	$	(2,606	)	$	(1,648	)	$	(2,382	)	$	(2,521	)
Net loss per share – basic and diluted	$	(2.18	)	$	(1.22	)	$	(1.67	)	$	(1.68	)

Organization and Basis of Presentation - Additional Information (Details) $ in Thousands		12 Months Ended
	Jul. 06, 2018	Dec. 31, 2018 USD ($) Segment	Dec. 31, 2017 USD ($)
Organization And Basis Of Presentation [Line Items]
Number of operating segments \| Segment		1
Cash, cash equivalents and investments		$ 163,900
Accumulated deficit		$ 43,380	$ 16,265
Minimum
Organization And Basis Of Presentation [Line Items]
Period of sufficient cash to meet its funding requirements		12 months
Common Stock
Organization And Basis Of Presentation [Line Items]
Stock reverse stock split	1-for-3.29
Stock split conversion ratio	0.3040

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Feb. 29, 2016
Summary Of Significant Accounting Policies [Line Items]
Impairment losses of long-lived assets	$ 0
Accounting Standards Update 2016-02
Summary Of Significant Accounting Policies [Line Items]
Operating Lease, Liability				$ 6,200,000
Operating lease ROU asset				2,800,000
Unamortized lease incentives				$ 3,400,000
Australian Research and Development Tax Incentive \| Australian Taxation Office
Summary Of Significant Accounting Policies [Line Items]
Tax incentive receivable, reductions to research and development expense	$ 1,200,000	$ 500,000	$ 0
Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life	3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life	5 years

Investment Securities - Summary of Available-For-Sale Short-Term Investments Held by the Company (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale investment securities, Amortized Cost	$ 118,841
Available-for-sale investment securities, Gross Unrealized Gains	74
Available-for-sale investment securities, Gross Unrealized Losses	(13)
Available-for-sale investment securities, Fair Market Value	118,902
U.S. Government and Agency Obligations
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale investment securities, Amortized Cost	42,193
Available-for-sale investment securities, Gross Unrealized Gains	72
Available-for-sale investment securities, Gross Unrealized Losses	(1)
Available-for-sale investment securities, Fair Market Value	42,264
Certificates of Deposit
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale investment securities, Amortized Cost	5,408
Available-for-sale investment securities, Fair Market Value	5,408
Commercial Paper
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale investment securities, Amortized Cost	47,686
Available-for-sale investment securities, Fair Market Value	47,686
Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale investment securities, Amortized Cost	23,554
Available-for-sale investment securities, Gross Unrealized Gains	2
Available-for-sale investment securities, Gross Unrealized Losses	(12)
Available-for-sale investment securities, Fair Market Value	$ 23,544

Investment Securities - Additional Information (Details)	Dec. 31, 2018 Security
Investments Debt And Equity Securities [Abstract]
Available-for-sale investment securities maturity period, maximum	24 months
Available-for-sale, unrealized loss position, twelve month or more	0

Fair Value Measurements - Schedule of Financial Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	$ 118,902,000	$ 0
Level 1
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	22,275,000
Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	96,627,000
Commercial Paper
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	47,686,000
Commercial Paper \| Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	47,686,000
Certificates of Deposit
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	5,408,000
Certificates of Deposit \| Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	5,408,000
Corporate Debt Securities
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	23,544,000
Corporate Debt Securities \| Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	23,544,000
U.S. Government and Agency Obligations
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	42,264,000
U.S. Government and Agency Obligations \| Level 1
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	22,275,000
U.S. Government and Agency Obligations \| Level 2
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Total assets measured at fair value	$ 19,989,000

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value assets transferred into level 3	$ 0
Fair value assets transferred out of level 3	0
Fair value liabilities transferred into level 3	0
Fair value liabilities transferred out of level 3	0
Fair Value, Measurements, Recurring
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Assets, fair value disclosure	$ 118,902,000	$ 0
Fair Value, Measurements, Nonrecurring
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Assets, fair value disclosure		0
Liabilities, fair value disclosure		$ 0

Balance Sheet Details - Components of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
SBIR grant receivable	$ 568	$ 231
Australian tax incentive receivable	1,016	503
Prepaid expenses and other assets	1,224	239
Total	$ 2,808	$ 973

Balance Sheet Details - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Property and equipment at cost	$ 4,973	$ 704
Accumulated depreciation and amortization	(741)	(304)
Total	4,232	400
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment at cost	3,494	18
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment at cost	915	640
Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment at cost	523	19
Computers and Software
Property Plant And Equipment [Line Items]
Property and equipment at cost	$ 41	$ 27

Balance Sheet Details - Components of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Accrued research and development costs	$ 3,634	$ 126
Deferred rent	381
Other accrued expenses	175	53
Total	$ 4,190	$ 179

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018
Loss Contingencies [Line Items]
Rent expense	$ 0.6	$ 0.2	$ 0.1
2018 Operating Lease
Loss Contingencies [Line Items]
Operating lease, initial term				7 years
Operating lease, option to extend term	five years
Irrevocable letter of credit				$ 0.5

Commitments and Contingencies - Schedule of Future Minimum Payments Under Non-cancellable Operating Leases (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 1,058
2020	1,123
2021	1,173
2022	1,208
2023	1,244
Thereafter	2,151
Total	$ 7,957

Convertible Preferred Stock - Additional Information (Details) - USD ($)		2 Months Ended	9 Months Ended	12 Months Ended
	Jul. 20, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Temporary Equity [Line Items]
Proceeds from issuance of convertible preferred stock, net of issuance costs				$ 63,275,000	$ 11,969,000	$ (5,000)
Series B Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares issued		19,641,200
Proceeds from issuance of convertible preferred stock, net of issuance costs		$ 63,500,000
Convertible preferred stock, issuance costs		$ 200,000
Series A Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares issued			11,505,268		11,505,268
Proceeds from issuance of convertible preferred stock, net of issuance costs			$ 12,000,000
Convertible preferred stock, issuance costs			$ 40,000
Series A and B Convertible Preferred Stock \| Initial Public Offering
Temporary Equity [Line Items]
Stock issued upon conversion of convertible securities	14,712,571

Stockholders Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Jul. 20, 2018	Oct. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Proceeds from IPO net of underwriting discounts and commissions and offering costs			$ 106,472
Common stock, shares authorized			200,000,000	50,500,000
Preferred stock, shares authorized			10,000,000	10,000,000
Stock-based compensation expenses			$ 2,320	$ 271	$ 270
Stock Restriction Agreement
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrestricted shares of common stock repurchased		1,914,893
Common stock repurchase rights lapsed		765,957
Common stock repurchase rights to be lapsed monthly thereafter till fully vested in October 2019			23,936
Unrestricted shares of common stock fair value		$ 1,400
Stock-based compensation expenses			$ 400	$ 200	$ 200
IPO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Proceeds from IPO net of underwriting discounts and commissions and offering costs	$ 106,500
Common stock, shares authorized	200,000,000
Preferred stock, shares authorized	10,000,000
Common Stock \| IPO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share of common stock issued	6,900,000		6,900,000
Sale of stock, price per share	$ 17.00

Equity Incentive Plans - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Jul. 31, 2018	Feb. 28, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average fair value of stock options granted to employees per share			$ 4.66	$ 0.85	$ 0.43
Unrecognized stock-based compensation cost			$ 7.9
Weighted-average period of unrecognized stock-based compensation cost expected to be recognized over remaining period			3 years 4 months 24 days
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum percentage of eligible compensation to purchase common stock through payroll deductions	20.00%
Unrecognized stock-based compensation cost			$ 0.6
Weighted-average period of unrecognized stock-based compensation cost expected to be recognized over remaining period			1 year 4 months 24 days
2018 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Plan expiration period	2028-07
Plan expiration term	10 years
Vesting period	4 years
Plan expiration date			Jan. 01, 2028
2015 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Plan expiration term		10 years
Vesting period		4 years
Shares issued under early-exercise provisions subject to repurchase			127,058
Unvested stock liability			$ 0.2
Common Stock \| ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for issuance, authorized	250,000		230,461
Plan expiration date	Jan. 01, 2028
Incremental percentage of shares authorized each year applied on outstanding number of shares	1.00%
Additional shares available for issuance	241,875
Common Stock \| 2018 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for issuance, authorized	1,991,636		1,855,396
Incremental percentage of shares authorized each year applied on outstanding number of shares			5.00%
Common Stock \| 2018 Plan \| Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional shares available for issuance						1,209,378

Equity Incentive Plans - Summary of 2018 Activity (and Related Information) under 2018 and 2015 Plan (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options Outstanding, Beginning balance \| shares	838,276
Options Outstanding, Granted \| shares	2,002,332
Options Outstanding, Exercised \| shares	(479,287)
Options Outstanding, Forfeited and expired \| shares	(22,164)
Options Outstanding, Ending balance \| shares	2,339,157
Options Outstanding, Exercisable \| shares	250,090
Weighted-Average Exercise Price, Beginning balance \| $ / shares	$ 0.80
Weighted-Average Exercise Price, Granted \| $ / shares	7.37
Weighted Average Exercise Price, Exercised \| $ / shares	0.94
Weighted Average Exercise Price, Forfeited and expired \| $ / shares	0.91
Weighted-Average Exercise Price, Ending balance \| $ / shares	6.40
Weighted-Average Exercise Price, Exercisable \| $ / shares	$ 4.54
Weighted-Average Remaining Term, Ending balance	9 years
Weighted-Average Remaining Term, Exercisable	8 years 1 month 6 days
Exercised \| $	$ 2,403
Aggregate Intrinsic Value, Ending balance \| $	55,257
Aggregate Intrinsic Value, Exercisable \| $	$ 6,366

Equity Incentive Plans - Summarizes the Weighted Average Assumptions Used to Estimate Fair Value of Stock Options Granted to Employees (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life of option	1 year 1 month 6 days
Volatility	66.00%
Risk free interest rate	2.40%
Employee Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected life of option	6 years	6 years	6 years 1 month 6 days
Volatility	70.00%	71.00%	64.00%
Risk free interest rate	2.80%	2.10%	1.50%

Equity Incentive Plans - Summary of Stock-based Compensation Expense for the Equity Awards Issued to Employees and Non-Employees (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 2,320	$ 271	$ 270
Included in Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,100	122	108
Included in General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,220	$ 149	$ 162

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Federal operating loss carryforwards	$ 8,700,000
State operating loss carryforwards	10,900,000
Domestic operating loss carryforwards	100,000
Research and development credit carryforwards	$ 1,788,000	$ 829,000
Operating loss and research and development credit carryforwards, limitations on use	Future utilization of the Company’s NOL and R&D credit carryforwards to offset future taxable income may be subject to a substantial annual limitation as a result of ownership changes that may have occurred or that could occur in the future pursuant to Internal Revenue Code Sections 382 and 383. These ownership changes may limit the amount of NOL and R&D credit carryforwards that can be utilized to offset future taxable income and tax, respectively. In general, an “ownership change” as defined by the tax code results from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percent of the outstanding stock of a company by certain stockholders or public groups.
U.S. federal corporate tax rate	21.00%	35.00%
Reduction in the deferred tax asset balance	$ 1,600,000
Interest and penalties related to income tax matters	$ 0	$ 0	$ 0
Minimum
Operating Loss Carryforwards [Line Items]
Cumulative change in ownership percentage	50.00%
Maximum
Operating Loss Carryforwards [Line Items]
Period for cumulative change in ownership	3 years
California
Operating Loss Carryforwards [Line Items]
Research and development credit carryforwards	$ 900,000
Federal
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards, future taxable income, offset percentage	80.00%
Research and development credit carryforwards	$ 1,400,000
Research and development credit carryforwards, begin to expire	2030
Federal \| Earliest Tax Year
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration year	2035
State \| Earliest Tax Year
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards expiration year	2035

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Capitalized research expenses	$ 6,355	$ 2,127
Net operating loss carryforwards	2,664	1,863
Research and development and other tax credits	1,788	829
Accrued expenses	2,479	38
Fixed assets	(866)	(22)
Other, net	157	23
Total deferred tax assets, net	12,577	4,858
Less: valuation allowance	(12,577)	(4,858)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Schedule of Domestic and Foreign Pre-Tax Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Loss before income taxes - Domestic	$ (25,876)	$ (8,141)	$ (6,019)
Loss before income taxes - Foreign	(1,239)	(1,016)
Loss before income taxes - Consolidated	$ (27,115)	$ (9,157)	$ (6,019)

Income Taxes - Schedule of Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Expected income tax benefit at federal statutory rate	$ (5,694)	$ (3,113)	$ (2,046)
State income tax benefit, net of federal benefit	(1,758)	(474)	(327)
Change in valuation allowance	7,724	2,112	2,511
Research and development credit	(1,129)	(525)	(342)
Federal rate change	(52)	1,602	0
Australian tax incentive	362	176	0
Other	547	222	204
Total	$ 0	$ 0	$ 0

Income Taxes - Schedule of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Beginning balance	$ 159	$ 68	$ 0
Increase (decrease) for prior year tax positions	0	0	0
Increase (decrease) for current year tax positions	185	91	68
Ending balance	$ 344	$ 159	$ 68

Net Loss Per Share - Schedule of Potentially Dilutive Securities (in Common Stock Equivalent Shares) not Included in Calculation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities (in common stock equivalent shares) excluded from calculation of diluted net loss per share	2,466	10,108	6,916
Convertible Preferred Stock Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities (in common stock equivalent shares) excluded from calculation of diluted net loss per share		8,743	5,246
Common Stock Option
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities (in common stock equivalent shares) excluded from calculation of diluted net loss per share	2,339	838	856
Unvested Common Stock Subject to Repurchase
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities (in common stock equivalent shares) excluded from calculation of diluted net loss per share	127	527	814

Quarterly Data (unaudited) - Summary of Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Grant revenues	$ 781	$ 548	$ 657	$ 442	$ 528	$ 640	$ 832	$ 45	$ 2,428	$ 2,045	$ 589
Type Of Revenue Extensible List	us-gaap:GrantMember	us-gaap:GrantMember	us-gaap:GrantMember	us-gaap:GrantMember	us-gaap:GrantMember	us-gaap:GrantMember	us-gaap:GrantMember	us-gaap:GrantMember	us-gaap:GrantMember	us-gaap:GrantMember	us-gaap:GrantMember
Research and development expenses	$ 7,651	$ 6,886	$ 5,222	$ 4,720	$ 2,562	$ 2,523	$ 2,083	$ 2,065	$ 24,479	$ 9,233	$ 5,100
General and administrative expenses	2,561	1,732	1,118	1,248	467	491	392	589	6,659	1,939	1,533
Total operating expenses	10,212	8,618	6,340	5,968	3,029	3,014	2,475	2,654	31,138	11,172	6,633
Net loss	$ (8,495)	$ (7,588)	$ (5,568)	$ (5,464)	$ (2,521)	$ (2,382)	$ (1,648)	$ (2,606)	$ (27,115)	$ (9,157)	$ (6,019)
Net loss per share - basic and diluted	$ (0.35)	$ (0.38)	$ (2.41)	$ (2.92)	$ (1.68)	$ (1.67)	$ (1.22)	$ (2.18)	$ (2.23)	$ (6.68)	$ (5.96)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details