Aptinyx (APTX) 10-Q 12 Nov 19 2019 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2019	Nov. 08, 2019
Document and Entity Information
Entity Registrant Name	Aptinyx Inc.
Entity Central Index Key	0001674365
Document Type	10-Q
Document Period End Date	Sep. 30, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		33,679,965
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 114,214	$ 150,637
Restricted cash	179	252
Accounts receivable	461	578
Prepaid expenses and other current assets	3,980	1,784
Total current assets	118,834	153,251
Other assets	166	673
Property and equipment, net	1,330	1,690
Total assets	120,330	155,614
Current liabilities:
Accounts payable	1,750	1,889
Accrued expenses and other current liabilities	5,344	3,996
Total current liabilities	7,094	5,885
Other long-term liabilities	309	418
Total liabilities	7,403	6,303
Commitments and contingencies (see note 10)
Stockholders' equity:
Preferred stock, $0.01 par value, 10,000 shares authorized and no shares issued and outstanding as of June 30, 2019 and December 31, 2018
Common stock, $0.01 par value, 150,000 shares authorized as of June 30, 2019 and December 31, 2018, 33,608 and 33,341 issued and outstanding as of June 30, 2019 and December 31, 2018	337	333
Additional paid-in capital	261,760	254,516
Accumulated deficit	(149,170)	(105,538)
Total stockholders’ equity	112,927	149,311
Total liabilities and stockholders’ equity	$ 120,330	$ 155,614

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - $ / shares shares in Thousands	Sep. 30, 2019	Dec. 31, 2018
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000	10,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	150,000	150,000
Common stock, shares issued	33,676	33,341
Common stock, shares outstanding	33,676	33,341

Condensed Statements of Operati

Condensed Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues
Total revenues	$ 936	$ 943	$ 2,751	$ 5,535
Operating expenses:
Research and development	11,761	11,950	33,732	37,860
General and administrative	4,523	3,782	14,419	7,853
Total operating expenses	16,284	15,732	48,151	45,713
Loss from operations	(15,348)	(14,789)	(45,400)	(40,178)
Other income	558	608	1,768	990
Net loss and comprehensive loss	$ (14,790)	$ (14,181)	$ (43,632)	$ (39,188)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.44)	$ (0.43)	$ (1.30)	$ (2.48)
Weighted-average number of common shares outstanding, basic and diluted (in shares)	33,646	33,191	33,510	15,789
Collaboration revenue
Revenues
Total revenues	$ 936	$ 943	$ 2,751	$ 3,893
Grant revenue
Revenues
Total revenues				$ 1,642

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss	$ (43,632)	$ (39,188)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	345	336
Stock-based compensation expense	6,966	1,984
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(1,563)	356
Accounts receivable	117	344
Accounts payable	(139)	(263)
Accrued expenses and other liabilities	1,279	3,966
Net cash used in operating activities	(36,627)	(32,465)
Cash flows from investing activities:
Purchases of property and equipment	(43)	(391)
Net cash used in investing activities	(43)	(391)
Cash flows from financing activities:
Payment of deferred issuance costs associated with Series B convertible preferred stock financing		(232)
Proceeds from initial public offering, net of underwriters discounts		109,517
Proceeds from stock options exercised	282	2
Payment of deferred offering costs	(181)	(2,971)
Net cash provided by financing activities	101	106,316
Net (decrease) increase in cash, cash equivalents and restricted cash	(36,569)	73,460
Cash, cash equivalents and restricted cash, at beginning of period	151,128	92,609
Cash, cash equivalents and restricted cash, at end of period	114,559	166,069
Supplemental disclosure of non-cash investing and financing activities:
Deferred offering costs not yet paid	$ 17	$ 41

Condensed Statements of Convert

Condensed Statements of Convertible Preferred Stock shares in Thousands, $ in Thousands	9 Months Ended
	Sep. 30, 2018USD ($)shares
Convertible Preferred Stock Rollforward
Issuance of common stock upon IPO, net of underwriters' discount and other offering costs of $2,902	$ 106,505
Common stock
Convertible Preferred Stock Rollforward
Issuance of common stock upon IPO, net of underwriters' discount and other offering costs of $2,902	$ 74
Issuance of common stock upon IPO, net of underwriters' discount and other offering costs of $2,902 (in shares) | shares	7,360
Additional paid-in capital
Convertible Preferred Stock Rollforward
Issuance of common stock upon IPO, net of underwriters' discount and other offering costs of $2,902	$ 106,431
Series A-1
Convertible Preferred Stock Rollforward
Convertible preferred stock beginning balance	$ 22,650
Convertible preferred stock shares beginning balance | shares	151,773
Conversion of preferred stock upon IPO	$ (22,650)
Conversion of preferred stock upon IPO (in shares) | shares	(151,773)
Series A-2
Convertible Preferred Stock Rollforward
Convertible preferred stock beginning balance	$ 39,979
Convertible preferred stock shares beginning balance | shares	173,453
Conversion of preferred stock upon IPO	$ (39,979)
Conversion of preferred stock upon IPO (in shares) | shares	(173,453)
Series B
Convertible Preferred Stock Rollforward
Convertible preferred stock beginning balance	$ 69,757
Convertible preferred stock shares beginning balance | shares	234,955
Conversion of preferred stock upon IPO	$ (69,757)
Conversion of preferred stock upon IPO (in shares) | shares	(234,955)

Condensed Statements of Stockho

Condensed Statements of Stockholders' (Deficit) Equity - USD ($) shares in Thousands, $ in Thousands	Common stock	Additional paid-in capital	Accumulated deficit	Total
Stockholders' (deficit) equity beginning balance at Dec. 31, 2017	$ 53	$ 12,486	$ (52,257)	$ (39,718)
Stockholders' (deficit) equity shares beginning balance at Dec. 31, 2017	5,342
Stockholders' (Deficit) Equity Rollforward
Issuance of common stock upon vesting of restricted stock	$ 2	(2)
Issuance of common stock upon vesting of restricted stock (in shares)	220
Stock-based compensation		1,984		1,984
Conversion of preferred stock upon IPO	$ 203	132,183		132,386
Conversion of preferred stock upon IPO (in shares)	20,306
Issuance of common stock upon IPO, net of underwriters' discount and other offering costs of $2,902	$ 74	106,431		106,505
Issuance of common stock upon IPO, net of underwriters' discount and other offering costs of $2,902 (in shares)	7,360
Issuance of common stock upon exercise of stock options		2		2
Issuance of common stock upon exercise of stock options (in shares)	1
Net loss			(39,188)	(39,188)
Stockholders' (deficit) equity shares ending balance at Sep. 30, 2018	33,229
Stockholders' (deficit) equity ending balance at Sep. 30, 2018	$ 332	253,084	(91,445)	161,971
Stockholders' (deficit) equity beginning balance at Jun. 30, 2018	$ 332	252,473	(77,264)	175,541
Stockholders' (deficit) equity shares beginning balance at Jun. 30, 2018	33,155
Stockholders' (Deficit) Equity Rollforward
Issuance of common stock upon vesting of restricted stock (in shares)	73
Stock-based compensation		720		720
Issuance of common stock upon IPO, net of underwriters' discount and other offering costs of $2,902		(111)		(111)
Issuance of common stock upon exercise of stock options		2		2
Issuance of common stock upon exercise of stock options (in shares)	1
Net loss			(14,181)	(14,181)
Stockholders' (deficit) equity shares ending balance at Sep. 30, 2018	33,229
Stockholders' (deficit) equity ending balance at Sep. 30, 2018	$ 332	253,084	(91,445)	161,971
Stockholders' (deficit) equity beginning balance at Dec. 31, 2018	$ 333	254,516	(105,538)	$ 149,311
Stockholders' (deficit) equity shares beginning balance at Dec. 31, 2018	33,341			33,341
Stockholders' (Deficit) Equity Rollforward
Issuance of common stock upon vesting of restricted stock	$ 2	(2)
Issuance of common stock upon vesting of restricted stock (in shares)	193
Stock-based compensation		6,966		$ 6,966
Issuance of common stock upon exercise of stock options	$ 2	280		282
Issuance of common stock upon exercise of stock options (in shares)	142
Net loss			(43,632)	$ (43,632)
Stockholders' (deficit) equity shares ending balance at Sep. 30, 2019	33,676			33,676
Stockholders' (deficit) equity ending balance at Sep. 30, 2019	$ 337	261,760	(149,170)	$ 112,927
Stockholders' (deficit) equity beginning balance at Jun. 30, 2019	$ 336	259,090	(134,380)	125,046
Stockholders' (deficit) equity shares beginning balance at Jun. 30, 2019	33,608
Stockholders' (Deficit) Equity Rollforward
Issuance of common stock upon vesting of restricted stock	$ 1	(1)
Issuance of common stock upon vesting of restricted stock (in shares)	54
Stock-based compensation		2,641		2,641
Issuance of common stock upon exercise of stock options		30		30
Issuance of common stock upon exercise of stock options (in shares)	14
Net loss			(14,790)	$ (14,790)
Stockholders' (deficit) equity shares ending balance at Sep. 30, 2019	33,676			33,676
Stockholders' (deficit) equity ending balance at Sep. 30, 2019	$ 337	$ 261,760	$ (149,170)	$ 112,927

Condensed Statements of Stock_2

Condensed Statements of Stockholders’ (Deficit) Equity (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018
Statements of stockholders' (deficit) equity
Stock issuance costs capitalized	$ 2,902	$ 2,902

Organization

Organization	9 Months Ended
	Sep. 30, 2019
Organization
Organization	1. Organization Description of business Aptinyx Inc. (the “Company” or “Aptinyx”) was incorporated in Delaware on June 24, 2015 and maintains its headquarters in Evanston, Illinois. Aptinyx is a clinical‑stage biopharmaceutical company focused on the discovery, development, and commercialization of novel, proprietary, synthetic small molecules for the treatment of brain and nervous system disorders. Aptinyx has a platform for discovering proprietary compounds that work through a novel mechanism: modulation of N‑methyl‑D‑aspartate receptors (“NMDAr”), which are vital to normal and effective brain and nervous system functions. This mechanism has applicability across numerous brain and nervous system disorders. Initial public offering On June 20, 2018, the Company’s registration statement on Form S ‑ 1 (File No. 333‑225150) relating to the initial public offering (“IPO”) of its common stock became effective and on June 25, 2018, the IPO closed. Pursuant to the IPO, the Company issued and sold 7,359,998 shares of common stock at a public offering price of $16.00 per share, which included 959,999 shares sold pursuant to the exercise of the underwriters’ option to purchase additional shares. The Company received net proceeds of $106.5 million after deducting underwriting discounts and commissions and other offering costs of $3.0 million. The shares began trading on the Nasdaq Global Select Market on June 21, 2018. Upon the closing of the IPO, all of the Company’s outstanding shares of convertible preferred stock automatically converted into 20,306,497 shares of common stock at the applicable conversion ratio. At the market offering program On July 1, 2019, the Company entered into a Sales Agreement (the “Sales Agreement”) with Cowen and Company, LLC (“Cowen”), pursuant to which the Company may issue and sell, from time to time, shares of its common stock having an aggregate offering price of up to $50.0 million through Cowen as sales agent. Cowen may sell common stock by any method permitted by law deemed to be an “at the market offering” as defined in Rule 415(a)(4) of the Securities Act, including sales made directly on or through the Nasdaq Global Select Market or any other existing trade market for the common stock, in negotiated transactions at market prices prevailing at the time of sale or at prices related to prevailing market prices, or any other method permitted by law. Cowen will be entitled to receive 3.0% of the gross sales price per share of common stock sold under the Sales Agreement. As of the date of these financial statements, no shares of common stock have been issued and sold pursuant to the Sales Agreement. Liquidity and capital resources As of September 30, 2019, the Company had cash and cash equivalents of $114.2 million, which the Company believes will be sufficient to funds its planned operations for a period of at least twelve months from the date of issuance of these condensed financial statements.

Summary of significant accounti

Summary of significant accounting policies	9 Months Ended
	Sep. 30, 2019
Summary of significant accounting policies
Summary of significant accounting policies	2. Basis of presentation The condensed financial statements of the Company included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. The accompanying condensed financial statements reflect all adjustments consisting of normal, recurring adjustments that are necessary for a fair presentation of the financial position, results of operations and cash flows for the interim periods presented. Interim results are not necessarily indicative of results for a full year. Accordingly, these condensed financial statements should be read in conjunction with the financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 (the “Annual Report”) filed with the SEC on March 21, 2019. From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”), or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial statements upon adoption. Under the Jumpstart Our Business Startups Act of 2012, as amended (the “JOBS Act”), the Company meets the definition of an emerging growth company, and has elected the extended transition period for complying with new or revised accounting standards, which delays the adoption of these accounting standards until they would apply to private companies. Reverse stock split On June 7, 2018, the Company effected a one-for‑27.58621 reverse stock split of the Company’s issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for the Company’s convertible preferred stock. The par value per share and authorized shares of common and convertible preferred stock were not adjusted as a result of the reverse stock split. All common stock and common stock per share amounts within the financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to this reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital. Use of estimates The condensed financial statements are prepared in conformity with GAAP. This process requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates. Significant accounting policies The Company’s significant accounting policies are described in Note 3, “Summary of significant accounting policies,” in the Annual Report. There have been no material changes to the significant accounting policies during the nine months ended September 30, 2019 with the exception of the following: Revenue Recognition Revenue is recognized in accordance with revenue recognition accounting guidance, which utilizes five steps to determine whether revenue can be recognized and to what extent: (i) identify the contract with a customer; (ii) identify the performance obligation(s); (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) determine the recognition period. The Company only applies the five-step model to contracts when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, Revenue from Contracts with Customers, the Company assesses the goods or services promised within each contract and determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Significant judgments exercised by management include the identification of performance obligations, and whether such promised goods or services are considered distinct. The Company evaluates promised goods or services on a contract by contract basis to determine whether each promise represents a good or service that is distinct or has the same pattern of transfer as other promises. A promised good or service is considered distinct if the customer can benefit from the good or service independently of other goods/services either in the contract or that can be obtained elsewhere, without regard to contract exclusivity, and the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contact. If the good or service is not considered distinct, the Company combines such promises and accounts for them as a single combined performance obligation. Recently adopted accounting pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, which amends the guidance for accounting for revenue from contracts with customers. This ASU supersedes the revenue recognition requirements in ASC Topic 605, Revenue Recognition , (“ASC 605”), and creates a new topic, ASC 606, Revenue from Contracts with Customers . Through subsequent targeted amendments, the FASB issued additional ASUs that delayed the effective date of ASC 606 and clarified various aspects of the new revenue guidance, including principal versus agent considerations, identifying performance obligations, licensing, and other improvements and practical expedients. The Company adopted this new standard on January 1, 2019 using the modified retrospective transition method. The Company presents revenue from contracts with customers as collaboration revenue in the Company’s condensed statements of operations. The Company applied this new standard to all contracts with customers that were not complete as of the adoption date and has determined that no cumulative catch-up adjustment to accumulated deficit was required. See Note 4, “Research collaboration agreement with Allergan” for additional information regarding the Company’s single contract that falls within the scope of ASC 606. The Company has determined that the accounting for the Company’s various grant agreements is outside the scope of ASC 606, as the government agencies granting the Company funds are not receiving reciprocal value for their contributions. There are currently no grants outstanding in 2019. Since the accounting for government grants falls outside the scope of ASC 606, the Company has classified the grant income earned in 2018 separate and apart from revenue earned from contracts with customers in the Company’s condensed statements of operations. In June 2018, the FASB issued ASU 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting . This ASU expands the scope of Topic 718, Compensation—Stock Compensation to include share-based payments issued to nonemployees for goods or services. Under the new guidance, the existing employee guidance will apply to nonemployee share based transactions (as long as the transaction is not effectively a form of financing), with the exception of specific guidance related to the attribution of compensation cost. The cost of nonemployee awards will continue to be recorded as if the grantor had paid cash for the goods or services. The new accounting guidance will be effective for the Company on January 1, 2020. The Company has early adopted this new standard on January 1, 2019. The adoption did not have a material impact on the Company’s condensed financial statements. Recently issued accounting pronouncement In February 2016, the FASB issued ASU No. 2016‑02, Leases (“ASU 2016‑02”), which requires a lessee to recognize assets and liabilities on the balance sheet for operating leases and changes many key definitions, including the definition of a lease. The new standard includes a short‑term lease exception for leases with a term of 12 months or less, as part of which a lessee can make an accounting policy election not to recognize lease assets and lease liabilities. Lessees will continue to differentiate between finance leases (previously referred to as capital leases) and operating leases using classification criteria that are substantially similar to the previous guidance. The new standard will be effective for the Company beginning after December 15, 2019, and early adoption is permitted. The Company is currently evaluating the potential impact ASU 2016‑02 may have on its condensed financial statements.

Supplemental financial informat

Supplemental financial information	9 Months Ended
	Sep. 30, 2019
Supplemental financial information
Supplemental financial information	3. Supplemental financial information Cash, cash equivalents and restricted cash Cash and cash equivalents consist of cash and, if applicable, highly liquid investments with an original maturity of three months or less when purchased. The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets that sum to the total of the same such amounts shown in the condensed statements of cash flows (amounts in thousands). As of As of September 30, December 31, Cash and cash equivalents $ 114,214 $ 150,637 Short-term and long-term restricted cash 345 491 Total cash, cash equivalents, and restricted cash shown in the statements of cash flows $ 114,559 $ 151,128 Prepaid expenses and other current assets Prepaid expenses and other current assets consist of the following (in thousands): As of As of September 30, December 31, Prepaid clinical $ 1,970 $ 728 Prepaid insurance 1,220 673 Prepaid manufacturing costs 435 — Other prepaid expenses and current assets 355 383 Total prepaid expenses and other current assets $ 3,980 $ 1,784 Accrued expenses and other current liabilities Accrued expenses and other current liabilities consist of the following (in thousands): As of As of September 30, December 31, Employee-related expenses $ 1,954 $ 2,043 Development costs and sponsored research 1,746 915 Clinical trials 1,176 607 Professional services 125 211 Other 343 220 Total accrued expenses and other current liabilities $ 5,344 $ 3,996

Research collaboration agreemen

Research collaboration agreement with Allergan	9 Months Ended
	Sep. 30, 2019
Research collaboration agreement with Allergan
Research collaboration agreement with Allergan	4. Research collaboration agreement with Allergan On July 24, 2015, the Company entered into a Research Collaboration Agreement (“RCA”) with Naurex Inc., a subsidiary of Allergan plc (“Allergan”), focused on the research and discovery of small molecules that modulate NMDArs. The collaboration is supervised by a Joint Steering Committee (“JSC”) comprising an equal number of representatives from both the Company and Allergan. Under the terms of the agreement, the RCA will terminate upon the earlier of a predetermined anniversary of the RCA or on the date on which Allergan exercises three options to acquire molecules from a pool of eligible compounds. Under the terms of the agreement, Allergan will pay the Company $1.0 million for each option exercised by Allergan. On May 16, 2018, Allergan exercised its option to acquire exclusive rights to develop and commercialize AGN-241751 within a predefined set of indications. The Company concluded that Allergan meets the definition of a customer, and therefore concluded that the RCA represents a contract with a customer that falls within the scope of ASC 606. Performance obligations The Company identified the following promised goods or services within the RCA: · Research Licenses – the Company provides access to exclusive licenses under all of the Company’s NMDAr technologies, during the research term for the sole purpose of conducting research and development activities. Historically, the Company’s licenses have held no value to the customer on a standalone basis, as the research compounds were in the early discovery phase and required the Company’s expertise for further development. Accordingly, the Research Licenses are not considered distinct. · Research and Development Services – the Company provides research and development services that are performed on behalf of, or with, Allergan. As discussed within Research Licenses above, the Company’s licenses have historically held no value without the specialized research and development services. As the Company generally only provides research and development services for internally generated small molecules that modulate NMDArs which require a license to be utilized by a third party, the Research and Development Services are not considered distinct. · Joint Steering Committee – the Company actively participates in a joint steering committee, which allows the Company and its collaboration partner to direct the progression and prioritization of the joint discovery programs. As the steering committee would not occur or benefit the customer without the use of the Research Licenses and the related Research and Development Services, and given the Company’s proprietary knowledge of the Research Licenses and the NMDAr technologies, this is not considered distinct. The Company also evaluated whether the option granted to the customer to acquire additional goods or services represented a material right at contract inception. Upon Allergan’s exercise of one of its options, the Company is obligated to transfer control of all intellectual property relating to the optioned compound to Allergan, after which the Company has no further interest in, or continuing involvement with, such optioned compound. The Company evaluated the customer options for material rights, that is, whether the option was to acquire additional goods or services for free or at a discount, and concluded that the options are priced, at contract inception, at standalone selling price. Consequently, the customer options do not represent a performance obligation at the outset of the arrangement since they are contingent upon the option exercise which is outside of the Company’s control. The Company has concluded that there is a single combined performance obligation (comprising the Research Licenses, Research and Development Services and participation on the Joint Steering Committee) which is satisfied over time, as the research and development services are performed. The exercise of the option to acquire exclusive rights to develop and commercialize AGN-241751 or any future options exercised are not considered a performance obligation until the time of option exercise. Transaction Price The RCA includes both fixed and variable consideration. Fixed payments, such as contractually defined fees per full-time employee (“FTE”), are included in the transaction price at contract inception, while variable consideration, such as reimbursement for Research and Development Services, are estimated and then evaluated for constraints upon inception of the contract and evaluated on a quarterly basis thereafter. Research and Development Services are updated for actual invoices. There were no capitalized costs associated with obtaining the contract. The Company concluded that it will use an input method to measure proportional performance and to calculate the corresponding amount of revenue to recognize. The Company uses fixed FTE efforts and variable out-of-pocket costs as actual costs incurred relative to the annual budget research plan to measure progress towards fulfillment of the performance obligation. An input method of revenue recognition requires management to make estimates of costs to complete the Company’s performance obligations. In making such estimates, significant judgment is required to evaluate assumptions related to cost estimates. The cumulative effect of revisions to estimated costs to complete the Company’s performance obligations will be recorded in the period in which changes are identified and amounts can be reasonably estimated. The Company does not anticipate significant changes as the research plan is reviewed and adjusted annually and approved by the JSC. There are no significant financing components in the contract. The Company has determined that the option fee is representative of standalone selling price and concluded that it will recognize revenue for the option fee at a point in time, on the date of exercise, due to the significant uncertainty of whether or not Allergan would exercise the option. The Company recognizes the option fee at a point in time because control of the underlying intellectual property transfers to the customer, and the customer is able to use and benefit from the license. The Company has no further rights, interests or remaining performance obligations associated with any optioned compound, once exercised. During each of the three months ended September 30, 2019 and 2018, the Company recorded expenses of $1.9 million for certain development activities in accordance with the terms of the RCA, of which 50% was reimbursed by Allergan. The Company received reimbursements of $0.9 million during each of the three months ended September 30, 2019 and 2018. During the nine months ended September 30, 2019 and 2018, the Company recorded expenses of $5.5 million and $5.8 million, respectively, for certain development activities in accordance with the terms of the RCA, of which 50% was reimbursed by Allergan. The Company received reimbursements of $2.8 million and $2.9 million during the nine months ended September 30, 2019 and 2018, respectively. Such reimbursements were reported within collaboration revenue in the condensed statements of operations. All of the Company’s accounts receivables as of both September 30, 2019 and December 31, 2018 relate to amounts owed by Allergan under the RCA. On May 16, 2018, Allergan exercised its option to acquire exclusive rights to develop and commercialize AGN-241751 within a specific set of indications. For the three and nine months ended September 30, 2018, the Company recognized the $1.0 million non-refundable milestone payment within collaboration revenue in the condensed statements of operations as there were no remaining performance obligations associated with the optioned compound.

Fair value measurements

Fair value measurements	9 Months Ended
	Sep. 30, 2019
Fair value measurements
Fair value measurements	5. Fair value measurements ASC 820, Fair Value Measurement (“ASC 820”), establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). ASC 820 identifies fair value as the exchange price, or 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 a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tier fair value hierarchy that distinguishes between the following: · Level 1 inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities; · Level 2 inputs are inputs other than quoted prices included within Level 1 that are observable for the asset or liability, either directly or indirectly; and · Level 3 inputs are unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying values reported in the Company’s balance sheets for cash and cash equivalents, restricted cash, accounts receivable, accounts payable, and accrued expenses are reasonable estimates of their fair values due to the short-term nature of these items. Assets measured at fair value as of September 30, 2019 are as follows (in thousands): September 30, Level 1 Level 2 Level 3 Assets Money market funds, included in cash and cash equivalents $ 114,059 $ 114,059 $ — $ — Money market funds, included in restricted cash 179 179 — — Money market funds, included in other assets 166 166 — — $ 114,404 $ 114,404 $ — $ — Assets measured at fair value as of December 31, 2018 are as follows (in thousands): December 31, Level 1 Level 2 Level 3 Assets Money market funds, included in cash and cash equivalents $ 150,151 $ 150,151 $ — $ — Money market funds, included in restricted cash 252 252 — — Money market funds, included in other assets 239 239 — — $ 150,642 $ 150,642 $ — $ —

Property and equipment

Property and equipment	9 Months Ended
	Sep. 30, 2019
Property and equipment
Property and equipment	6 . Property and equipment Property and equipment are as follows (in thousands): As of As of September 30, December 31, Computer software and equipment $ 15 $ 15 Office equipment and furniture 176 176 Laboratory equipment 1,614 1,571 Leasehold improvements 1,051 1,051 Less accumulated depreciation (1,526) (1,123) Property and equipment, net $ 1,330 $ 1,690 Depreciation expense was $0.1 million for each of the three months ended September 30, 2019 and 2018, and $0.4 million for each of the nine months ended September 30, 2019 and 2018.

Stock incentive plans

Stock incentive plans	9 Months Ended
	Sep. 30, 2019
Stock incentive plans
Stock incentive plans	7. Stock incentive plans On June 5, 2018, the Company’s stockholders approved the 2018 Stock Option and Incentive Plan (the “2018 Plan”), which became effective on June 20, 2018. The 2018 Plan provides for an annual increase, to be added on the first day of each fiscal year, of up to 4% of the Company’s outstanding shares of common stock as of the last day of the prior year. On January 1, 2019, 1,341,436 shares of common stock were added to the 2018 Plan. The number of shares available for grant under the Company’s 2018 Plan as of September 30, 2019 was 2,809,289 which includes 505,046 shares of the Company’s common stock reserved under the Company’s 2015 Stock Option and Grant Plan (the “2015 Plan”) that became available for issuance upon the effectiveness of the 2018 Plan. No future issuance will be made under the 2015 Plan. Stock‑based compensation expense Non-cash stock-based compensation expense recognized in the accompanying condensed statements of operations relating to both stock options, restricted stock awards and restricted stock units for the three and nine months ended September 30, 2019 and 2018 was as follows (in thousands): Three months ended Nine months ended September 30, September 30, Research and development $ 816 $ 242 $ 2,181 $ 616 General and administrative 1,825 478 4,785 1,368 Total stock‑based compensation expense $ 2,641 $ 720 $ 6,966 $ 1,984 Stock options The table below summarizes activity related to stock options (in thousands, except per share amounts): Weighted‑ Weighted‑ average average remaining Aggregate exercise contractual intrinsic Options Shares price term value Outstanding, December 31, 2018 3,959 $ 7.46 8.79 $ 35,984 Granted 1,663 12.77 Exercised (142) 1.99 Forfeited and canceled (522) 11.91 Outstanding, September 30, 2019 4,958 $ 8.93 8.45 $ 1,356 Vested and expected to vest at September 30, 2019 4,958 $ 8.93 8.45 $ 1,356 Exercisable at September 30, 2019 1,877 $ 5.37 7.90 $ 968 During the nine months ended September 30, 2019 and 2018, the Company granted 1.7 million and 2.4 million stock options, respectively and these options had a weighted-average grant-date fair value of $8.36 and $9.95 per share, respectively. The weighted-average grant-date fair value of options was determined using the Black-Scholes option-pricing model. The assumptions used in the Black-Scholes option-pricing model for options granted during the three and nine months ended September 30, 2019 were similar to those as described in the Annual Report. As of September 30, 2019, there was $20.4 million of total unrecognized stock-based compensation expense related to non-vested stock options which is expected to be recognized over a weighted-average period of 2.90 years. The options have a ten-year life and generally vest over a period of four years, subject to continuous employment. Restricted stock awards Non-cash restricted stock award expense recognized in the accompanying condensed statements of operations was $0.1 million for each of the three months ended September 30, 2019 and 2018 and $0.3 million for each of the nine months ended September 30, 2019 and 2018. The total fair value of shares that vested in the nine months ended September 30, 2019 was $0.2 million. At September 30, 2019, there was less than $0.1 million of unrecognized compensation cost related to 3,632 unvested restricted stock awards that will be recognized as expense over a weighted-average period of less than 0.01 years. Restricted stock units In May 2019, the Company issued an aggregate of 1,183,400 shares of restricted stock units to employees. The restricted stock units vest in two years from the date of grant. The Company at any time may accelerate the vesting of the restricted stock units. Such shares are not accounted for as outstanding until they vest. There are 2,166 shares of common stock underlying restricted stock units outstanding as of September 30, 2019. The table below summarizes activity related to restricted stock units (in thousands, except per share amounts): Weighted‑ average grant date fair value Shares per share Unvested as of December 31, 2018 - $ - Issued 1,183 $ 3.63 Vested (2) 3.63 Forfeited and canceled (26) 3.63 Unvested as of September 30, 2019 1,155 $ 3.63 Non-cash restricted stock unit award expense recognized in the accompanying condensed statements of operations was $0.6 million and $0.8 million for the three and nine months ended September 30, 2019, respectively. At September 30, 2019, there was $3.4 million of unrecognized compensation related to 1,154,934 unvested restricted stock units that will be recognized as expense over a weighted-average period of 1.63 years.

Net loss per share

Net loss per share	9 Months Ended
	Sep. 30, 2019
Net loss per share
Net loss per share	8. Net loss per share Basic and diluted net loss per share attributable to common stockholders was calculated as follows for the three and nine months ended September 30, 2019 and 2018 (in thousands, except per share data): Three months ended Nine months ended September 30, September 30, Numerator: Net loss attributable to common stockholders $ (14,790) $ (14,181) $ (43,632) $ (39,188) Denominator: Weighted-average common shares outstanding—basic and diluted 33,646 33,191 33,510 15,789 Net loss per share attributable to common stockholders—basic and diluted $ (0.44) $ (0.43) $ (1.30) $ (2.48) The following common stock equivalents outstanding as of September 30, 2019 and 2018, were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been anti‑dilutive (in thousands): As of September 30, Stock options issued and outstanding 4,958 3,937 Unvested restricted stock 1,159 268 Total 6,117 4,205

Income taxes

Income taxes	9 Months Ended
	Sep. 30, 2019
Income taxes
Income taxes	9. Income taxes Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax bases of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are provided if based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets, including its net operating losses. Based on its history of operating losses, the Company believes that it is more likely than not that the benefit of its deferred tax assets will not be realized. Accordingly, the Company has provided a full valuation allowance for deferred tax assets as of September 30, 2019 and December 31, 2018.

Commitments and contingencies

Commitments and contingencies	9 Months Ended
	Sep. 30, 2019
Commitments and contingencies
Commitments and contingencies	10. Commitments and contingencies Contingencies From time to time, the Company may be subject to occasional lawsuits, investigations and claims arising out of the normal conduct of business. The Company has no significant pending or threatened litigation as of September 30, 2019. Indemnifications In the normal course of business, the Company enters into contracts that contain a variety of indemnifications with its employees, licensors, suppliers and service providers. Further, the Company indemnifies its directors and officers who are, or were, serving at the Company’s request in such capacities. The Company’s maximum exposure under these arrangements is unknown at September 30, 2019. The Company does not anticipate recognizing any significant losses relating to these arrangements. Leases The Company enters into various non-cancelable, operating lease agreements for its facilities and equipment in order to conduct its operations. The Company expenses rent on a straight-line basis over the life of the lease and has recorded deferred rent on the Company’s balance sheets within both accrued expenses and other current liabilities and other long-term liabilities. Total rent expense, inclusive of lease incentives, under all the operating lease agreements amounted to $0.2 million for each of the three months ended September 30, 2019 and 2018 and $0.6 million and $0.5 million for the nine months ended September 30, 2019 and 2018, respectively.

Summary of significant accoun_2

Summary of significant accounting policies (Policies)	9 Months Ended
	Sep. 30, 2019
Summary of significant accounting policies
Reverse stock split	Reverse stock split On June 7, 2018, the Company effected a one-for‑27.58621 reverse stock split of the Company’s issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for the Company’s convertible preferred stock. The par value per share and authorized shares of common and convertible preferred stock were not adjusted as a result of the reverse stock split. All common stock and common stock per share amounts within the financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to this reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital.
Use of estimates	Use of estimates The condensed financial statements are prepared in conformity with GAAP. This process requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates.
Revenue Recognition	Revenue Recognition Revenue is recognized in accordance with revenue recognition accounting guidance, which utilizes five steps to determine whether revenue can be recognized and to what extent: (i) identify the contract with a customer; (ii) identify the performance obligation(s); (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) determine the recognition period. The Company only applies the five-step model to contracts when it is probable that the Company will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, Revenue from Contracts with Customers, the Company assesses the goods or services promised within each contract and determines those that are performance obligations and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. Significant judgments exercised by management include the identification of performance obligations, and whether such promised goods or services are considered distinct. The Company evaluates promised goods or services on a contract by contract basis to determine whether each promise represents a good or service that is distinct or has the same pattern of transfer as other promises. A promised good or service is considered distinct if the customer can benefit from the good or service independently of other goods/services either in the contract or that can be obtained elsewhere, without regard to contract exclusivity, and the entity’s promise to transfer the good or service to the customer is separately identifiable from other promises in the contact. If the good or service is not considered distinct, the Company combines such promises and accounts for them as a single combined performance obligation.
Recent adopted and issued accounting pronouncements	Recently adopted accounting pronouncements In May 2014, the FASB issued Accounting Standards Update (“ASU”) No. 2014-09, which amends the guidance for accounting for revenue from contracts with customers. This ASU supersedes the revenue recognition requirements in ASC Topic 605, Revenue Recognition , (“ASC 605”), and creates a new topic, ASC 606, Revenue from Contracts with Customers . Through subsequent targeted amendments, the FASB issued additional ASUs that delayed the effective date of ASC 606 and clarified various aspects of the new revenue guidance, including principal versus agent considerations, identifying performance obligations, licensing, and other improvements and practical expedients. The Company adopted this new standard on January 1, 2019 using the modified retrospective transition method. The Company presents revenue from contracts with customers as collaboration revenue in the Company’s condensed statements of operations. The Company applied this new standard to all contracts with customers that were not complete as of the adoption date and has determined that no cumulative catch-up adjustment to accumulated deficit was required. See Note 4, “Research collaboration agreement with Allergan” for additional information regarding the Company’s single contract that falls within the scope of ASC 606. The Company has determined that the accounting for the Company’s various grant agreements is outside the scope of ASC 606, as the government agencies granting the Company funds are not receiving reciprocal value for their contributions. There are currently no grants outstanding in 2019. Since the accounting for government grants falls outside the scope of ASC 606, the Company has classified the grant income earned in 2018 separate and apart from revenue earned from contracts with customers in the Company’s condensed statements of operations. In June 2018, the FASB issued ASU 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting . This ASU expands the scope of Topic 718, Compensation—Stock Compensation to include share-based payments issued to nonemployees for goods or services. Under the new guidance, the existing employee guidance will apply to nonemployee share based transactions (as long as the transaction is not effectively a form of financing), with the exception of specific guidance related to the attribution of compensation cost. The cost of nonemployee awards will continue to be recorded as if the grantor had paid cash for the goods or services. The new accounting guidance will be effective for the Company on January 1, 2020. The Company has early adopted this new standard on January 1, 2019. The adoption did not have a material impact on the Company’s condensed financial statements. Recently issued accounting pronouncement In February 2016, the FASB issued ASU No. 2016‑02, Leases (“ASU 2016‑02”), which requires a lessee to recognize assets and liabilities on the balance sheet for operating leases and changes many key definitions, including the definition of a lease. The new standard includes a short‑term lease exception for leases with a term of 12 months or less, as part of which a lessee can make an accounting policy election not to recognize lease assets and lease liabilities. Lessees will continue to differentiate between finance leases (previously referred to as capital leases) and operating leases using classification criteria that are substantially similar to the previous guidance. The new standard will be effective for the Company beginning after December 15, 2019, and early adoption is permitted. The Company is currently evaluating the potential impact ASU 2016‑02 may have on its condensed financial statements.

Supplemental financial inform_2

Supplemental financial information (Tables)	9 Months Ended
	Sep. 30, 2019
Supplemental financial information
Schedule of cash, cash equivalents and restricted cash	The following table provides a reconciliation of cash, cash equivalents, and restricted cash reported within the balance sheets that sum to the total of the same such amounts shown in the condensed statements of cash flows (amounts in thousands). As of As of September 30, December 31, Cash and cash equivalents $ 114,214 $ 150,637 Short-term and long-term restricted cash 345 491 Total cash, cash equivalents, and restricted cash shown in the statements of cash flows $ 114,559 $ 151,128
Schedule of prepaid expenses and other current assets	Prepaid expenses and other current assets consist of the following (in thousands): As of As of September 30, December 31, Prepaid clinical $ 1,970 $ 728 Prepaid insurance 1,220 673 Prepaid manufacturing costs 435 — Other prepaid expenses and current assets 355 383 Total prepaid expenses and other current assets $ 3,980 $ 1,784
Schedule of accrued expenses and other current liabilities	Accrued expenses and other current liabilities consist of the following (in thousands): As of As of September 30, December 31, Employee-related expenses $ 1,954 $ 2,043 Development costs and sponsored research 1,746 915 Clinical trials 1,176 607 Professional services 125 211 Other 343 220 Total accrued expenses and other current liabilities $ 5,344 $ 3,996

Fair value measurements (Tables

Fair value measurements (Tables)	9 Months Ended
	Sep. 30, 2019
Fair value measurements
Schedule of assets measured at fair value	Assets measured at fair value as of September 30, 2019 are as follows (in thousands): September 30, Level 1 Level 2 Level 3 Assets Money market funds, included in cash and cash equivalents $ 114,059 $ 114,059 $ — $ — Money market funds, included in restricted cash 179 179 — — Money market funds, included in other assets 166 166 — — $ 114,404 $ 114,404 $ — $ — Assets measured at fair value as of December 31, 2018 are as follows (in thousands): December 31, Level 1 Level 2 Level 3 Assets Money market funds, included in cash and cash equivalents $ 150,151 $ 150,151 $ — $ — Money market funds, included in restricted cash 252 252 — — Money market funds, included in other assets 239 239 — — $ 150,642 $ 150,642 $ — $ —

Property and equipment (Tables)

Property and equipment (Tables)	9 Months Ended
	Sep. 30, 2019
Property and equipment
Schedule of property and equipment	Property and equipment are as follows (in thousands): As of As of September 30, December 31, Computer software and equipment $ 15 $ 15 Office equipment and furniture 176 176 Laboratory equipment 1,614 1,571 Leasehold improvements 1,051 1,051 Less accumulated depreciation (1,526) (1,123) Property and equipment, net $ 1,330 $ 1,690

Stock incentive plans (Tables)

Stock incentive plans (Tables)	9 Months Ended
	Sep. 30, 2019
Stock incentive plans
Allocation of stock-based compensation expenses	Non-cash stock-based compensation expense recognized in the accompanying condensed statements of operations relating to both stock options, restricted stock awards and restricted stock units for the three and nine months ended September 30, 2019 and 2018 was as follows (in thousands): Three months ended Nine months ended September 30, September 30, Research and development $ 816 $ 242 $ 2,181 $ 616 General and administrative 1,825 478 4,785 1,368 Total stock‑based compensation expense $ 2,641 $ 720 $ 6,966 $ 1,984
Summary of stock option activity	The table below summarizes activity related to stock options (in thousands, except per share amounts): Weighted‑ Weighted‑ average average remaining Aggregate exercise contractual intrinsic Options Shares price term value Outstanding, December 31, 2018 3,959 $ 7.46 8.79 $ 35,984 Granted 1,663 12.77 Exercised (142) 1.99 Forfeited and canceled (522) 11.91 Outstanding, September 30, 2019 4,958 $ 8.93 8.45 $ 1,356 Vested and expected to vest at September 30, 2019 4,958 $ 8.93 8.45 $ 1,356 Exercisable at September 30, 2019 1,877 $ 5.37 7.90 $ 968
Schedule of restricted stock unit activity	The table below summarizes activity related to restricted stock units (in thousands, except per share amounts): Weighted‑ average grant date fair value Shares per share Unvested as of December 31, 2018 - $ - Issued 1,183 $ 3.63 Vested (2) 3.63 Forfeited and canceled (26) 3.63 Unvested as of September 30, 2019 1,155 $ 3.63

Net loss per share (Tables)

Net loss per share (Tables)	9 Months Ended
	Sep. 30, 2019
Net loss per share
Schedule of basic and diluted net loss per share attributable to common stockholders calculation	Basic and diluted net loss per share attributable to common stockholders was calculated as follows for the three and nine months ended September 30, 2019 and 2018 (in thousands, except per share data): Three months ended Nine months ended September 30, September 30, Numerator: Net loss attributable to common stockholders $ (14,790) $ (14,181) $ (43,632) $ (39,188) Denominator: Weighted-average common shares outstanding—basic and diluted 33,646 33,191 33,510 15,789 Net loss per share attributable to common stockholders—basic and diluted $ (0.44) $ (0.43) $ (1.30) $ (2.48)
Schedule of anti-dilutive securities excluded from computation of diluted net loss per share	The following common stock equivalents outstanding as of September 30, 2019 and 2018, were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been anti‑dilutive (in thousands): As of September 30, Stock options issued and outstanding 4,958 3,937 Unvested restricted stock 1,159 268 Total 6,117 4,205

Organization (Details)

Organization (Details) - USD ($) $ / shares in Units, $ in Thousands	Jul. 01, 2019	Jun. 25, 2018	Sep. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Organization
Payment of offering costs				$ 181	$ 2,971
Cash and cash equivalents			$ 114,214	$ 114,214		$ 150,637
Expected period of sufficient funds for planned operations				12 months
IPO
Organization
Common stock issued and sold in initial public offering (in shares)		7,359,998
Public offering price of the shares sold		$ 16
Net proceeds from issuance of common stock		$ 106,500
Payment of offering costs		$ 3,000
Number of preferred stock converted into common stock		20,306,497
New shares issued under the agreement		7,359,998
Underwriters' option
Organization
Common stock issued and sold in initial public offering (in shares)		959,999
New shares issued under the agreement		959,999
Sales Agreement
Organization
Common stock issued and sold in initial public offering (in shares)			0
Stock sale maximum aggregate offering price	$ 50,000
Stock sale commission percentage	3.00%
New shares issued under the agreement			0

Summary of significant accoun_3

Summary of significant accounting policies (Details)	Jun. 07, 2018	Sep. 30, 2019item
Summary of significant accounting policies
Reverse stock split ratio	0.03625
Grants outstanding		0

Supplemental financial inform_3

Supplemental financial information - Cash, cash equivalents and restricted cash (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Supplemental financial information
Cash and cash equivalents	$ 114,214	$ 150,637
Short-term and long-term restricted cash	345	491
Total cash, cash equivalents, and restricted cash shown in the statements of cash flows	$ 114,559	$ 151,128	$ 166,069	$ 92,609

Supplemental financial inform_4

Supplemental financial information - Prepaid expenses and other current assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Supplemental financial information
Prepaid clinical	$ 1,970	$ 728
Prepaid insurance	1,220	673
Prepaid Manufacturing Cost	435
Other prepaid expenses and current assets	355	383
Total prepaid expenses and other current assets	$ 3,980	$ 1,784

Supplemental financial inform_5

Supplemental financial information - Accrued expenses and other current liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Supplemental financial information
Employee-related expenses	$ 1,954	$ 2,043
Development costs and sponsored research	1,746	915
Clinical trials	1,176	607
Professional services	125	211
Other	343	220
Total accrued expenses and other current liabilities	$ 5,344	$ 3,996

Research collaboration agreem_2

Research collaboration agreement with Allergan (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Jul. 24, 2015USD ($)Option
Research collaboration agreement with Allergan
Research and development	$ 11,761	$ 11,950	$ 33,732	$ 37,860
Non-Refundable Milestone Payment		1,000		1,000
RCA
Research collaboration agreement with Allergan
Payment of option exercise fee					$ 1,000
Number of options to acquire molecules | Option					3
capitalized contract costs	0		0
Research and development	$ 1,900	$ 1,900	$ 5,500	$ 5,800
Development activities reimbursement percentage	50.00%	50.00%	50.00%	50.00%
Development activities expenses reimbursed	$ 900	$ 900	$ 2,800	$ 2,900
Remaining performance obligation		$ 0		$ 0

Fair value measurements (Detail

Fair value measurements (Details) - Recurring - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Fair value measurements
Assets measured at fair value	$ 114,404	$ 150,642
Money market funds, included in cash and cash equivalents
Fair value measurements
Money market funds	114,059	150,151
Money market funds, included in restricted cash
Fair value measurements
Money market funds	179	252
Money market funds, included in other assets
Fair value measurements
Money market funds	166	239
Level 1
Fair value measurements
Assets measured at fair value	114,404	150,642
Level 1 | Money market funds, included in cash and cash equivalents
Fair value measurements
Money market funds	114,059	150,151
Level 1 | Money market funds, included in restricted cash
Fair value measurements
Money market funds	179	252
Level 1 | Money market funds, included in other assets
Fair value measurements
Money market funds	$ 166	$ 239

Property and equipment (Details

Property and equipment (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Property and equipment
Less accumulated depreciation		$ (1,526)		$ (1,123)
Property and equipment, net		1,330		1,690
Depreciation and amortization	$ 100	345	$ 336
Computer software and equipment
Property and equipment
Property and equipment, gross		15		15
Office equipment and furniture
Property and equipment
Property and equipment, gross		176		176
Laboratory equipment
Property and equipment
Property and equipment, gross		1,614		1,571
Leasehold improvements
Property and equipment
Property and equipment, gross		$ 1,051		$ 1,051

Stock incentive plans (Details)

Stock incentive plans (Details)	9 Months Ended
	Sep. 30, 2019shares
2018 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of increase in number of shares outstanding	4.00%
Common stock added to plan	1,341,436
Awards available for future grant	2,809,289
2015 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance	505,046

Stock incentive plans - Stock-b

Stock incentive plans - Stock-based compensation expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash restricted stock unit award expense recognized	$ 2,641	$ 720	$ 6,966	$ 1,984
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash restricted stock unit award expense recognized	816	242	2,181	616
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash restricted stock unit award expense recognized	$ 1,825	$ 478	$ 4,785	$ 1,368

Stock incentive plans - Activit

Stock incentive plans - Activity related to stock options (Details) - Stock options - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Shares
Outstanding, at the beginning of the period	3,959
Granted	1,663	2,400
Exercised	(142)
Forfeited and canceled	(522)
Outstanding, at the end of the period	4,958		3,959
Vested and expected to vest	4,958
Exercisable	1,877
Weighted-average exercise price
Outstanding, at the beginning of the period	$ 7.46
Granted	12.77
Exercised	1.99
Forfeited and canceled	11.91
Outstanding, at the end of the period	8.93		$ 7.46
Vested and expected to vest	8.93
Exercisable at the end of the period	$ 5.37
Weighted-average remaining contractual term
Weighted-average remaining contractual term	8 years 5 months 12 days		8 years 9 months 15 days
Vested and expected to vest	8 years 5 months 12 days
Exercisable	7 years 10 months 24 days
Aggregate intrinsic value
Outstanding, at the beginning of the period	$ 35,984
Outstanding, at the end of the period	1,356		$ 35,984
Vested and expected to vest	1,356
Exercisable	$ 968
Weighted-average grant date fair value per share	$ 8.36	$ 9.95
Unrecognized stock-based compensation related to non-vested stock options	$ 20,400
Expenses recognized over a weighted-average period (in years)	2 years 10 months 24 days
Term of award	10 years
Vesting period	4 years

Stock incentive plans - Restric

Stock incentive plans - Restricted stock awards (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Weighted‑average grant date fair value per share
Non-cash restricted stock unit award expense recognized	$ 2,641	$ 720	$ 6,966	$ 1,984
Restricted stock awards
Shares
Unvested at end of period (in shares)	3,632		3,632
Weighted‑average grant date fair value per share
Non-cash restricted stock unit award expense recognized	$ 100	$ 100	$ 300	$ 300
Fair value of shares vested			200
Restricted stock awards | Maximum
Weighted‑average grant date fair value per share
Unrecognized compensation related to unvested restricted stock units	$ 100		$ 100
Expenses recognized over a weighted-average period (in years)			4 days

Stock incentive plans - Restr_2

Stock incentive plans - Restricted stock units (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Weighted-average grant date fair value per share
Non-cash restricted stock unit award expense recognized		$ 2,641	$ 720	$ 6,966	$ 1,984
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years
Vested and outstanding awards		2,166		2,166
Shares
Issued (in shares)	1,183,400			1,183,000
Vested (in shares)				2,000
Forfeited and canceled (in shares)				(26,000)
Unvested at end of period (in shares)		1,154,934		1,154,934
Weighted-average grant date fair value per share
Issued (in dollars per share)				$ 3.63
Vested (in dollars per share)				3.63
Forfeited and canceled (in dollars per share)				3.63
Unvested at end of period (in dollars per share)		$ 3.63		$ 3.63
Non-cash restricted stock unit award expense recognized		$ 600		$ 800
Unrecognized compensation related to unvested restricted stock units		$ 3,400		$ 3,400
Expenses recognized over a weighted-average period (in years)				1 year 7 months 17 days

Net loss per share (Details)

Net loss per share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Numerator:
Net loss attributable to common stockholders	$ (14,790)	$ (14,181)	$ (43,632)	$ (39,188)
Denominator:
Weighted-average common shares outstanding—basic and diluted	33,646	33,191	33,510	15,789
Net loss per share attributable to common stockholders—basic and diluted	$ (0.44)	$ (0.43)	$ (1.30)	$ (2.48)

Net loss per share - Anti-dilut

Net loss per share - Anti-dilutive securities (Details) - shares shares in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Common stock equivalents outstanding excluded from the computation of diluted net loss per share attributable to common stockholders
Outstanding anti-dilutive securities excluded from computation of diluted net loss per share	6,117	4,205
Stock options
Common stock equivalents outstanding excluded from the computation of diluted net loss per share attributable to common stockholders
Outstanding anti-dilutive securities excluded from computation of diluted net loss per share	4,958	3,937
Unvested restricted stock
Common stock equivalents outstanding excluded from the computation of diluted net loss per share attributable to common stockholders
Outstanding anti-dilutive securities excluded from computation of diluted net loss per share	1,159	268

Commitments and contingencies (

Commitments and contingencies (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Commitments and contingencies
Rent expense inclusive of lease incentives	$ 0.2	$ 0.2	$ 0.6	$ 0.5

Subsequent events (Details)

Subsequent events (Details) - Sales Agreement - USD ($) $ in Millions	Jul. 01, 2019	Sep. 30, 2019
Subsequent Event [Line Items]
Stock sale maximum aggregate offering price	$ 50
Stock sale commission percentage	3.00%
New shares issued under the agreement		0