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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2017	Mar. 07, 2018	Jun. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	Gemphire Therapeutics Inc.
Entity Central Index Key	0001638287
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Filer Category	Non-accelerated Filer
Entity Public Float			$ 71.3
Entity Common Stock, Shares Outstanding		14,225,900
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 18,473	$ 24,033
Prepaid expenses	490	713
Deferred offering costs	21
Other assets	25
Total current assets	19,009	24,746
Deposits	8	8
Total assets	19,017	24,754
Current liabilities:
Accounts payable	4,025	2,008
Accrued liabilities	1,010	2,113
Term loan - current portion	1,355
Total current liabilities	6,390	4,121
Term loan	8,683
Other liabilities	3	1
Total liabilities	15,076	4,122
Commitments and contingencies (Note 5)
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized as of December 31, 2017 and 2016, no shares issued or outstanding as of December 31, 2017 and 2016.
Common stock, $0.001 par value; 100,000,000 shares authorized as of December 31, 2017 and 2016, 10,633,042 and 9,270,255 shares issued and outstanding at December 31, 2017 and 2016, respectively.	18	17
Additional paid in capital	64,397	47,674
Accumulated deficit	(60,474)	(27,059)
Total stockholders’ equity	3,941	20,632
Total liabilities and stockholders’ equity	$ 19,017	$ 24,754

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016	Aug. 03, 2016
Condensed Balance Sheets
Preferred Stock, Par Value (in dollar per share)	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000	10,000,000
Preferred Stock, shares issued	0	0
Preferred Stock, shares outstanding	0	0
Common Stock, Par Value (in dollar per share)	$ 0.001	$ 0.001
Common Stock, share authorized	100,000,000	100,000,000	100,000,000
Common Stock, share issued	10,633,042	9,270,255
Common Stock, share outstanding	10,633,042	9,270,255

Statements of Comprehensive Loss - USD ($)	3 Months Ended								12 Months Ended
Statements of Comprehensive Loss - USD ($)	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating expenses:
General and administrative	$ 1,487,000	$ 2,050,000	$ 4,678,000	$ 2,223,000	$ 2,389,000	$ 1,466,000	$ 1,051,000	$ 1,050,000	$ 10,438,000	$ 5,956,000	$ 3,177,000
Research and development	5,080,000	6,489,000	5,837,000	5,280,000	4,839,000	1,936,000	789,000	1,176,000	22,686,000	8,740,000	3,991,000
Acquired in-process research and development											908,000
Total operating expenses	6,567,000	8,539,000	10,515,000	7,503,000	7,228,000	3,402,000	1,840,000	2,226,000	33,124,000	14,696,000	8,076,000
Loss from operations	(6,567,000)	(8,539,000)	(10,515,000)	(7,503,000)	(7,228,000)	(3,402,000)	(1,840,000)	(2,226,000)	(33,124,000)	(14,696,000)	(8,076,000)
Interest (expense) income	(179,000)	(132,000)	13,000	12,000	13,000	(475,000)	449,000	127,000	(286,000)	114,000	(762,000)
Loss on convertible note extinguishment											(198,000)
Other (expense) income				(5,000)	1,000	(1,000)		(4,000)	(5,000)	(4,000)	7,000
Loss before income taxes	(6,746,000)	(8,671,000)	(10,502,000)	(7,496,000)	(7,214,000)	(3,878,000)	(1,391,000)	(2,103,000)	(33,415,000)	(14,586,000)	(9,029,000)
Provision (benefit) for income taxes									0
Net loss	(6,746,000)	(8,671,000)	(10,502,000)	(7,496,000)	(7,214,000)	(3,878,000)	(1,391,000)	(2,103,000)	(33,415,000)	(14,586,000)	(9,029,000)
Comprehensive loss	(6,746,000)	(8,671,000)	(10,502,000)	(7,496,000)	(7,214,000)	(3,878,000)	(1,391,000)	(2,103,000)	(33,415,000)	(14,586,000)	(9,029,000)
Net loss	$ (6,746,000)	$ (8,671,000)	$ (10,502,000)	$ (7,496,000)	(7,214,000)	(3,878,000)	(1,391,000)	(2,103,000)	(33,415,000)	(14,586,000)	(9,029,000)
Adjustment to redemption value on Series A convertible preferred stock						(67,000)	(150,000)	(149,000)		(366,000)	(2,968,000)
Premium upon substantial modification of convertible note with certain shareholders											1,047,000
Net loss attributable to common stockholders					$ (7,214,000)	$ (3,945,000)	$ (1,541,000)	$ (2,252,000)	$ (33,415,000)	$ (14,952,000)	$ (13,044,000)
Net loss per share:
Basic and diluted (Note 10)	$ (0.63)	$ (0.82)	$ (0.99)	$ (0.79)	$ 0.78	$ 0.56	$ 0.42	$ 0.65	$ (3.23)	$ (2.57)	$ (4.54)
Number of shares used in per share calculations:
Basic and diluted									10,349,136	5,809,396	2,875,053

Statements of Changes in Convertible Preferred Stock and Stockholders’ Equity (Deficit) - USD ($) $ in Thousands	Common Stock Private placement	Common Stock	Additional Paid-in Capital Private placement	Additional Paid-in Capital	Accumulated Deficit	Private placement	Total
Balance at beginning of period at Dec. 31, 2014		$ 9		$ 44	$ (584)		$ (531)
Balance at beginning of period (shares) at Dec. 31, 2014		3,036,236
Increase (Decrease) in Stockholders' Equity
Redemption value adjustment - Series A preferred stock				(1,130)	(1,838)		(2,968)
Issuance of common stock		$ 3		908			911
Issuance of common stock (shares)		677,685
Convertible note extinguishment Loss				(106)	(941)		(1,047)
Issuance of restricted stock awards (in shares)		44,567
Share-based compensation - employee				131			131
Share-based compensation - non-employee				153			153
Net loss					(9,029)		(9,029)
Balance at end of period at Dec. 31, 2015		$ 12			(12,392)		(12,380)
Balance at end of period (shares) at Dec. 31, 2015		3,758,488
Increase (Decrease) in Stockholders' Equity
Redemption value adjustment - Series A preferred stock				(285)	(81)		(366)
Conversion of preferred stock to common stock, amount		$ 1		8,318			8,319
Conversion of preferred stock to common stock (in shares)		827,205
Separation of beneficial conversion feature associated with convertible notes				372			372
Conversion of convertible notes to common stock, amount		$ 1		11,444			11,445
Conversion of convertible notes to common stock, shares		1,656,807
Issuance of common stock		$ 3		30,275			30,278
Issuance of common stock (shares)		3,027,755
Share-based compensation - employee				1,498			1,498
Share-based compensation - non-employee				220			220
Net loss					(14,586)		(14,586)
Issuance costs of offering				(4,168)			(4,168)
Balance at end of period at Dec. 31, 2016		$ 17		47,674	(27,059)		20,632
Balance at end of period (shares) at Dec. 31, 2016		9,270,255
Increase (Decrease) in Stockholders' Equity
Issuance of common stock	$ 1		$ 8,978			$ 8,979
Issuance of common stock (shares)	1,324,256
Share-based compensation - employee				5,244			5,244
Share-based compensation - non-employee				29			29
Net loss					(33,415)		(33,415)
Issuance of detachable stock warrants in connection with private placement offering			3,562			3,562
Issuance costs of offering			$ (1,287)			$ (1,287)
Exercise of stock options				41			41
Exercise of stock options (in shares)		23,531
Exercise of warrants				156			$ 156
Exercise of warrants (in shares)		15,000					15,000
Balance at end of period at Dec. 31, 2017		$ 18		$ 64,397	$ (60,474)		$ 3,941
Balance at end of period (shares) at Dec. 31, 2017		10,633,042

Statements of Changes in Convertible Preferred Stock and Stockholders’ Equity (Deficit) - Temporary Equity - 12 months ended Dec. 31, 2016 $ in Thousands	Series A Convertible Preferred Stock. USD ($) shares
Temporary equity, balance at beginning of period at Dec. 31, 2015	$ 7,953
Temporary equity, balance at beginning of period (shares) at Dec. 31, 2015 \| shares	745,637
Increase (Decrease) in Temporary Equity
Redemption value adjustment - Series A preferred stock	$ 366
Conversion of Series A preferred stock, amount converted	$ (8,319)
Conversion of Series A preferred stock, shares converted (shares) \| shares	(745,637)
Temporary equity, balance at end of period at Dec. 31, 2016	$ 0
Temporary equity, balance at end of period (shares) at Dec. 31, 2016 \| shares	0

Statements of Cash Flows - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net loss	$ (33,415)	$ (14,586)	$ (9,029)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	5,273	1,718	284
Non-cash interest on convertible notes to related parties		145	40
Non-cash interest on convertible notes		256	100
Non-cash discount amortization on convertible notes to related parties		(17)	62
Non-cash discount amortization on term loan and convertible notes	137	(276)	261
Revaluation of premium conversion derivative		(850)	297
Non-cash loss on extinguishment of convertible notes			198
Non-cash interest upon conversion of convertible notes		649
Non-cash acquisition of in-process research and development			908
Change in assets and liabilities:
Prepaid expenses and other assets	198	(55)	(10)
Accounts payable	2,007	1,477	444
Accrued and other liabilities	(1,101)	496	1,012
Net cash used in operating activities	(26,901)	(11,043)	(5,433)
Financing activities
Proceeds from issuance of term loan and convertible notes	10,000	2,651	5,560
Proceeds from issuance of convertible notes to related parties		2,500	1,856
Issuance costs related to term loan and convertible notes	(89)	(10)
Proceeds from issuance of Series A convertible preferred stock			1,522
Exercise of stock options	41		3
Exercise of warrants	156
Proceeds from sale of common stock and warrants	12,541	30,278
Offering costs	(1,287)	(3,963)	(205)
Deferred offering costs	(21)
Net cash provided by financing activities	21,341	31,456	8,736
Net (decrease) increase in cash and cash equivalents	(5,560)	20,413	3,303
Cash and cash equivalents at beginning of period	24,033	3,620	317
Cash and cash equivalents at end of period	18,473	24,033	3,620
Supplemental disclosure of cash flow information:
Cash paid for interest	291		2
Supplemental non-cash financing transactions:
Exercise of premium conversion derivative			685
Redemption value change of Series A preferred stock		366	$ 2,968
Issuance of common stock for acquisition of in-process research and development			908
Bifurcation of premium conversion derivative related to convertible notes		505	$ 842
Convertible note extinguishment			1,426
Premium conversion derivative reduction upon convertible note extinguishment			182
Separation of beneficial conversion feature associated with convertible notes		372
Other Assets
Supplemental non-cash financing transactions:
Offering costs in other assets paid in prior year		205
Accounts Payable and Accrued Liabilities
Supplemental non-cash financing transactions:
Issuance costs in accounts payable and accrued liabilities	$ 10		642
Conversion of Convertible Notes
Supplemental non-cash financing transactions:
Conversion of convertible notes to common stock		11,445
Conversion of Series A Preferred Stock
Supplemental non-cash financing transactions:
Conversion of Series A preferred stock to common stock		$ 8,319
Conversion of convertible notes to common stock			$ 2,778

The Company and Basis of Presentation	12 Months Ended
The Company and Basis of Presentation	Dec. 31, 2017
The Company and Basis of Presentation
The Company and Basis of Presentation	1. The Company and Basis of Presentation On November 10, 2008, Michigan Life Therapeutics, LLC (MLT) was organized as a limited liability company (LLC) in Michigan. On October 30, 2014, Gemphire Therapeutics Inc. (Gemphire or the Company) was incorporated as a C corporation in the state of Delaware. On November 1, 2014, MLT entered into a merger agreement with Gemphire whereby MLT was merged with and into Gemphire with Gemphire as the surviving entity; all outstanding membership interests of MLT were exchanged for shares of Gemphire’s common stock. The purpose of the merger was to change the jurisdiction of MLT from Michigan to Delaware and to convert from an LLC to a corporation. The Company’s headquarters are located in Livonia, Michigan. The Company is a clinical‑stage biopharmaceutical entity focused on developing and commercializing therapies for the treatment of dyslipidemia, a serious medical condition that increases the risk of life threatening cardiovascular disease, and NAFLD/NASH (nonalcoholic fatty liver disease). The Company’s primary activities to date have been conducting research and development activities, planning and conducting clinical trials, performing business and financial planning, recruiting personnel and raising capital. The Company is subject to certain risks, which include the need to research, develop, and clinically test potentially therapeutic products, initially one product candidate gemcabene (also known as CI‑1027); obtain regulatory approval for its products and commercialize them around the world; expand its management scientific staff; finance its operations; and, find collaboration partners to further advance development and commercial efforts. Initial Public Offering On August 4, 2016, the Company’s Registration Statement on Form S-1 (File No 333-210815) relating to its initial public offering (IPO) of its common stock was declared effective by the Securities and Exchange Commission (SEC). Pursuant to such Registration Statement, on August 10, 2016, the Company closed its IPO whereby 3,000,000 shares of its common stock were issued and sold at a public offering price of $10.00 per share. On September 8, 2016, the Company closed the sale of 27,755 shares of its common stock at the public offering price of $10.00 per share, representing a partial exercise of the underwriters’ over-allotment option, following which, the IPO terminated. The Company received net proceeds of approximately $26.1 million after deducting underwriting discounts and commissions of $2.1 million and other offering expenses of $2.1 million. Immediately prior to the IPO, the Company amended and restated its certificate of incorporation and bylaws to, among other things, change its authorized capital stock to consist of (i) 100,000,000 shares of common stock and (ii) 10,000,000 shares of undesignated preferred stock. Both the common stock and the preferred stock have a par value of $0.001 per share. Private Placement Offering On March 10, 2017, the Company entered into a securities purchase agreement for a private placement (the Private Placement) with a select group of accredited investors whereby, on March 15, 2017 the Company issued and sold 1,324,256 units at a price of $9.47 per unit for gross proceeds of approximately $12.5 million. Each unit consists of one share of the Company’s common stock and a warrant to purchase 0.75 shares of common stock. The warrants have an exercise price of $10.40 per share and are exercisable for a period of five years from the date of issuance. On April 20, 2017, the registration statement on Form S-1 (File No 333-217296) for the resale of the shares of common stock issued in the Private Placement and the shares of common stock to be issued upon exercise of the warrants issued in the Private Placement was declared effective by the SEC. Capital Requirements The Company has sustained operating losses since inception and expects such losses to continue over the next several years. Management plans to continue financing the Company’s operations with equity issuances. The Company’s management believes the cash and cash equivalents on hand are adequate to fund the Company’s operations for at least the next 12 months. If adequate funds are not available, the Company may be required to delay, reduce the scope of, or eliminate part or all of its research and development programs. Reverse Stock Split In April 2016, the board of directors approved an amendment to the Company’s certificate of incorporation to effect a 1-for-3.119 reverse stock split (the Reverse Stock Split) for all common and Series A preferred stock. The Reverse Stock Split became effective on April 27, 2016 upon the filing of the amendment to the certificate of incorporation. The authorized shares and par value of the common stock and Series A preferred stock were not adjusted as a result of the Reverse Stock Split. All issued and outstanding common and Series A preferred stock, options for common stock and per share amounts contained in the financial statements were retroactively adjusted to reflect the Reverse Stock Split for all periods presented.

Summary of Significant Accounting Policies	12 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2017
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of 90 days or less at the time of deposit to be cash equivalents. The Company invests excess cash in readily available checking and savings accounts and highly liquid investments in money market accounts. Fair Value of Financial Instruments The Company’s financial instruments include principally cash and cash equivalents, other current assets, accounts payable, accrued liabilities and debt. The carrying amounts for these financial instruments reported in the balance sheets approximate their fair values. See Note 11 — Fair Value Measurements, for further discussion of fair value. General and Administrative Expenses General and administrative expenses consist primarily of personnel‑related costs, including salaries and share‑based compensation costs, for personnel in functions not directly associated with research and development activities. Other significant costs include legal fees related to intellectual property and corporate matters and professional fees for accounting and other services. Research and Development Expenses Research and development expenses consist of costs incurred in performing research and development activities, including compensation for research and development employees, costs associated with preclinical studies and trials, regulatory activities, manufacturing activities to support clinical activities, license fees, non‑legal patent costs, fees paid to external service providers that conduct certain research and development, clinical costs and an allocation of overhead expenses. Research and development costs are expensed as incurred. Acquired In‑Process Research and Development Expenses The Company includes costs to acquire or in‑license product candidates in acquired in‑process research and development expenses. The Company has acquired the right to develop and commercialize its product candidate gemcabene. These costs are immediately expensed provided that the payments do not also represent processes or activities that would constitute a “business” as defined under GAAP or provided that the product candidate has not achieved regulatory approval for marketing and absent obtaining such approval, has no alternative future use. Royalties owed on future sales of any licensed product will be expensed in the period the related revenues are recognized. Income Taxes The Company utilizes the liability method of accounting for income taxes as required by Accounting Standards Codification (ASC) 740, Income Taxes. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and the tax basis of assets and liabilities and are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse. Currently, there is no provision for income taxes, as the Company has incurred operating losses to date, and a full valuation allowance has been provided on the net deferred tax assets. MLT was treated as a partnership for federal and state income tax purposes. Accordingly, no provision was made for income taxes for periods prior to November 1, 2014, since the Company’s net loss (subject to certain limitations) was passed through to the income tax returns of its members. Upon incorporation on October 30, 2014, the Company became taxed as a corporation. Share‑Based Compensation The Company accounts for share‑based compensation in accordance with the provisions of ASC 718, Compensation — Stock Compensation (ASC 718). Accordingly, compensation costs related to equity instruments granted are recognized at the grant‑date fair value. The Company records forfeitures when they occur. Share‑based compensation arrangements to non‑employees are accounted for in accordance with the applicable provisions of ASC 718 and ASC 505, Equity, using a fair value approach. The compensation costs of these arrangements are subject to re‑measurement as the equity instruments vest and are recognized as expense over the related service period (typically the vesting period of the awards). Common Stock Valuation Due to the absence of an active market for the Company’s common stock prior to the close of the IPO, the Company utilized methodologies in accordance with the framework of the American Institute of Certified Public Accountants’ Technical Practice Aid, Valuation of Privately‑Held Company Equity Securities Issued as Compensation, to estimate the fair value of its common stock. The valuation methodology included estimates and assumptions that required the Company’s judgment. These estimates and assumptions included a number of objective and subjective factors, including external market conditions affecting the biopharmaceutical industry sector, and the likelihood of achieving a liquidity event, such as an initial public offering or sale. Significant changes to the key assumptions used in the valuations could have resulted in different fair values of common stock at each valuation date. Convertible Preferred Stock On March 31, 2015, the Company issued 745,637 shares of Series A convertible preferred stock (the Series A preferred stock). On August 10, 2016, immediately prior to the closing of the IPO, the Company’s Series A preferred stock, together with accrued dividends thereon, converted into 827,205 shares of common stock. The Series A preferred stock prior to conversion was classified outside of permanent equity, in mezzanine equity, on the Company’s balance sheet. The Company initially records preferred stock that may be redeemed at the option of the holder, or based on the occurrence of events outside of the Company’s control, at the value of the proceeds received. Subsequently, if it is probable that the preferred stock will become redeemable, the Company recognizes changes in the redemption value immediately as they occur and adjusts the carrying amount of the instrument to equal the redemption value at the end of each reporting period. If it is not probable that the preferred stock will become redeemable, the Company does not adjust the carrying value. In the absence of retained earnings, these charges are recorded against additional paid‑in‑capital, if any, and then to accumulated deficit See Note 7 — Convertible Series A Preferred Stock for further discussion. As a result of their conversion to common stock on August 10, 2016 as described above, no shares of Series A preferred stock were outstanding as of December 31, 2017 and 2016. Segment Information Operating segments are components of an enterprise for which separate financial information is available and is evaluated regularly by the Company’s chief operating decision maker in deciding how to allocate resources and assessing performance. The Company’s chief operating decision maker is its Chief Executive Officer. The Company’s Chief Executive Officer views the Company’s operations and manages its business in one operating segment, which is the business of development and commercialization of therapeutics for the treatment of dyslipidemia, a serious medical condition that increases the risk of life threatening cardiovascular disease and NAFLD/NASH. Accordingly, the Company has a single reporting segment. Jumpstart Our Business Startups Act Accounting Election As an emerging growth company under the Jumpstart Our Business Startups Act (JOBS Act), the Company is eligible to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. The Company has irrevocably elected not to avail itself of this exemption and, therefore, will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies. Recent Accounting Pronouncements In May 2014, the FASB issued ASU 2014‑09, Revenue from Contracts with Customers — Topic 606, which supersedes the revenue recognition requirements in FASB ASC 605. The new guidance primarily states that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. In January 2017 and September 2017, the FASB issued several amendments to ASU 2014‑09, including updates stemming from SEC Accounting Staff Announcement in July 2017. The amendments and updates included clarification on accounting for principal versus agent considerations (i.e., reporting gross versus net), licenses of intellectual property and identification of performance obligations. These amendments and updates do not change the core principle of the standard, but provide clarity and implementation guidance. The Company will adopt this standard on January 1, 2018 and selected the modified retrospective transition method. The Company will modify its accounting policies to reflect the requirements of this standard however, the planned adoption will not affect the Company’s financial statements and related disclosures for these periods or future periods until the Company generates revenues. In January 2016, the FASB issued ASU No. 2016‑01, Financial Instruments — Overall: Recognition and Measurement of Financial Assets and Financial Liabilities. The guidance affects the accounting for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements of financial instruments. The guidance is effective in the first quarter of fiscal 2019. Early adoption is permitted for the accounting guidance on financial liabilities under the fair value option. The Company is currently evaluating the impact of the new guidance on its financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) and subsequently amended the guidance relating largely to transition considerations under the standard in January 2017. The objective of this update is to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those annual periods and is to be applied utilizing a modified retrospective approach. The Company is currently evaluating the new guidance to determine the impact it may have on its financial statements. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The objective of this ASU is to eliminate the diversity in practice related to the classification of restricted cash or restricted cash equivalents in the statement of cash flows. For public business entities, this ASU is effective for annual and interim reporting periods beginning after December 15, 2017, with early adoption permitted. The amendments in this update should be applied retrospectively to all periods presented. The Company will adopt this standard on January 1, 2018 and will not have a material impact on the Company’s financial statements. In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting (ASU 2016-09), which provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. This pronouncement is effective for annual reporting periods beginning after December 15, 2017. The Company will adopt this standard on January 1, 2018 and will not have a material impact on the Company’s financial statements. In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share, Distinguishing Liabilities from Equity and Derivatives and Hedging, which changes the accounting and earnings per share for certain instruments with down round features. The amendments in this ASU should be applied using a cumulative-effect adjustment as of the beginning of the fiscal year or retrospective adjustment to each period presented and is effective for annual periods beginning after December 15, 2018, and interim periods within those periods. The Company is currently evaluating the requirements of this new guidance and has not yet determined its impact on the Company’s financial statements. On December 22, 2017 the SEC staff issued Staff Accounting Bulletin 118 (SAB 118), which provides guidance on accounting for the tax effects of the Tax Cuts and Jobs Act (the TCJA). SAB 118 provides a measurement period that should not extend beyond one year from the enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the TCJA for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the TCJA is incomplete but for which they are able to determine a reasonable estimate, it must record a provisional amount in the financial statements. Provisional treatment is proper in light of anticipated additional guidance from various taxing authorities, the SEC, the FASB, and even the Joint Committee on Taxation. If a company cannot determine a provisional amount to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the TCJA. The Company has applied this guidance to its financial statements.

Accrued Liabilities

12 Months Ended

Dec. 31, 2017

Accrued Liabilities

Accrued Liabilities

3. Accrued Liabilities

Accrued liabilities consist of the following (in thousands):


	As of December 31,
	2017		2016
Accrued compensation and other payroll liabilities	$	306	$	706
Legal costs		91		54
Accrued interest		38		—
Other research and development expenses		522		1,259
Other general and administrative expenses		53		94
Total	$	1,010	$	2,113

Debt

12 Months Ended

Dec. 31, 2017

Debt

Debt

4. Debt

Term Loan

On July 24, 2017, the Company entered into a Loan and Security Agreement (the Loan Agreement) with Silicon Valley Bank (SVB) for a term loan of up to $15.0 million (the Term Loan), subject to funding in several tranches. The Company drew the initial tranche of $10.0 million on July 24, 2017. Conditioned on the occurrence of certain clinical and pre-clinical milestones, an additional tranche of $5.0 million may be available to be drawn by the Company through July 31, 2018. The Company is in compliance with the Loan Agreement covenants as of December 31, 2017.

All amounts advanced under the Term Loan mature on February 1, 2021 and have an interest-only monthly payment period through August 1, 2018; the interest-only period may be extended to February 1, 2019 conditioned on the occurrence of such clinical and pre-clinical milestones referenced above. Following the interest-only payment period, the Company will begin making monthly payments of principal and interest until the maturity date. Interest will accrue on the unpaid principal balance at a floating per annum rate equal to the prime rate, except that, following an event of default, interest will accrue at a rate up to 5% above the rate that is otherwise applicable. The prime rate in effect from inception of the Term Loan through December 31, 2017 ranged from 4.25% to 4.5%. Lastly, debt issue costs in the amount of $0.1 million were incurred as of December 31, 2017 and were recorded as a discount to the Term Loan and are being amortized ratably to interest expense over the term of the loan.

The Loan Agreement requires the Company to pay the following fees: (i) upon the maturity, acceleration or prepayment of the Term Loan, a final payment fee of 10% of the funded principal amount of the Term Loan which was recorded as a liability upon issue and then discounted to be subsequently amortized ratably to interest expense over the term of the loan, (ii) a success fee of 3.5% of the funded principal amount of the Term Loan in the event any of the following occur prior to 5:00 pm Eastern Time on July 24, 2024: (a) the Company receives FDA approval for any new drug application for gemcabene, (b) a sale or other transfer of all or substantially all of the assets of the Company occurs, (c) a merger or consolidation of the Company with or into another person or entity occurs where the holders of the Company’s outstanding voting equity securities immediately prior to such merger or consolidation hold less than a majority of the issued and outstanding voting equity securities of the successor immediately following such transaction or (d) any sale by the holders of the Company’s outstanding voting equity securities where such holders do not continue to hold at least a majority of the Company’s issued and outstanding voting equity securities, and (iii) upon termination of the Loan Agreement prior to the maturity date for any reason, a prepayment fee equal to 2% (if such prepayment occurs prior to the first anniversary of the Effective Date) or 1% (if such prepayment occurs thereafter) of the funded principal amount of the Term Loan.

In the event a positive clinical trial event as defined in the Loan Agreement does not occur by March 31, 2018, on such date, the Company must either (i) provide cash security and maintain a cash balance in a restricted account at SVB in an amount of at least 50% of the amounts the Company owes to SVB or (ii) prepay the Term Loan in its entirety. On November 10, 2017, the Company provided SVB evidence of a positive clinical trial event. In the event a pre-clinical event does not occur by July 31, 2018, on such date, the Company must either (i) provide cash security and maintain a cash balance in a restricted account at SVB in an amount of at least 100% of the amounts the Company owes to SVB or (ii) prepay the Term Loan in its entirety. In each case, if the Company chooses to prepay the Term Loan, in addition to the repayment of the outstanding principal and accrued and unpaid interest, the Company is required to pay the final payment fee and, if applicable, the success fee, but not the prepayment fee.

The Company recorded $0.3 million in interest expense related to the Term Loan for the year ended December 31, 2017.

As of December 31, 2017, minimum aggregate future payments under the Term Loan are as follows (in thousands):


	December 31,

2018	$	2,104
2019		4,281
2020		4,099
2021		1,333
Total minimum payments		11,817
Amount representing interest and discounts		(1,779)
Present value of minimum payments		10,038
Current portion		(1,355)
Long-term portion	$	8,683

Future minimum interest payments under the Term Loan are assumed at a 4.5% per annum rate.

Interim Notes

On July 31, 2015, the Company entered into a convertible interim note financing (collectively with the notes issued in December 2015, February 2016 and April 2016, the Interim Notes), pursuant to which certain investors agreed to loan the Company approximately $2.8 million. On August 10, 2016, immediately prior to the closing of the IPO, the Company’s Interim Notes, together with accrued interest thereon, converted into 1,656,807 shares of common stock.

The Interim Notes accrued interest at a rate of 8% per annum, compounded annually, and would automatically convert into shares issued to investors in the Company’s next equity financing round that results in gross proceeds of at least $5.0 million (a Qualified Financing). The conversion would be equal to unpaid principal at 115% plus any unpaid accrued interest. The investors would be paid out principal at 200% if a change of control occurred before the next financing round. In the event that a Qualified Financing, change of control, or an IPO did not occur before July 31, 2016, the parties would then negotiate a price for conversion into a new round of stock.

In December 2015, the Company amended the Interim Notes and certain investors agreed to loan the Company an additional $2.7 million for a revised financing total of $5.5 million. The Interim Notes continued to accrue interest at an 8% rate per annum compounded annually, but were amended to automatically convert into shares of the same class of the Company’s next convertible preferred stock financing round (the Preferred Stock Financing). The conversion into shares issued in the Preferred Stock Financing would be equal to unpaid principal at 115% plus unpaid accrued interest. In the event that either a change of control occurs or the Company completes a public transaction which results in the Company’s stockholders holding securities listed on a national securities exchange, including an IPO, before the Preferred Stock Financing, the Interim Notes, as amended, would automatically convert into shares of the Company’s common stock at a conversion price of $6.70585 per share (which represents the original issue price of the Series A preferred stock) based on 100% of outstanding principal and unpaid accrued interest. Lastly, if a Preferred Stock Financing, change of control, or public transaction did not occur before December 31, 2016, the parties agreed to then negotiate a conversion price into a new round of stock.

In February 2016, certain investors agreed to loan the Company an additional $0.2 million for a revised financing total of $5.6 million. The Interim Notes continued to accrue interest at an 8% rate per annum compounded annually, but were amended to automatically convert into shares of the same class of the Company’s next Preferred Stock Financing. The conversion into shares issued in the Preferred Stock Financing would be equal to unpaid principal at 115% plus unpaid accrued interest. In the event that either a change of control occurs or the Company completes a public transaction which results in the Company’s stockholders holding securities listed on a national securities exchange, including an IPO, before the Preferred Stock Financing, the Interim Notes, as amended, would automatically convert into shares of the Company’s common stock at a conversion price of $6.70585 per share (which represents the original issue price of the Series A preferred stock as adjusted for the Reverse Stock Split) based on 100% of outstanding principal and unpaid accrued interest. Lastly, if a Preferred Stock Financing, change of control, or public transaction did not occur before December 31, 2016, the parties agreed to then negotiate a conversion price into a new round of stock.

In April 2016, the Company amended the Interim Notes and certain investors agreed to loan the Company an additional $5.0 million for a revised financing total, including Interim Notes previously issued, of $10.6 million. The Interim Notes continued to accrue interest at an 8% rate per annum compounded annually, but were amended so that 125% of the unpaid principal and accrued interest, would automatically convert into shares of the same class of the Company’s next convertible preferred stock financing round of at least $5.0 million (the Qualified Financing). In the event that either a change of control occurs or the Company completes a public transaction which results in the Company’s stockholders holding securities listed on a national securities exchange, including an IPO, before the Qualified Financing, 100% of outstanding principal and unpaid accrued interest on the Interim Notes, as amended, would automatically convert into shares of the Company’s common stock at a conversion price of $6.70585 per share, as adjusted for the Reverse Stock Split. Lastly, if a Qualified Financing, change of control, or public transaction did not occur, the Interim Notes would become payable on demand anytime after December 31, 2016. The Company incurred issuance costs related to the April 2016 financing in the amount of $10,000. The Interim Notes were discounted for the issuance costs, and the discount was amortized to interest expense over their remaining term using the straight‑line method.

On August 10, 2016, immediately prior to the closing of the IPO, the Company’s Interim Notes, together with accrued interest thereon, converted into 1,656,807 shares of common stock. At the time of their issuance, the Interim Notes contained a conversion premium with regard to the conversion into shares at the time of the next Qualified Financing. The Company determined that the redemption feature under the Interim Notes qualified as an embedded derivative and was separated from its debt host. The bifurcation of the embedded derivative from its debt host resulted in a discount to the Interim Notes. The discount was amortized to interest expense over the term of the Interim Notes using the straight‑line method. The embedded derivative was accounted for separately on a fair market value basis. As a result of the conversion of the Interim Notes, together with accrued interest thereon, into common stock immediately prior to the closing of the IPO, there was no premium conversion derivative outstanding as of December 31, 2017 or 2016. The Company recorded the fair value changes of the premium conversion derivative associated with the Interim Notes to interest income (expense) that amounted to zero, $0.2 million, $(0.1) million for the years ended December 31, 2017, 2016 and 2015, respectively.

As a result of their conversion to common stock on August 10, 2016 as described above, there were no Interim Notes outstanding as of December 31, 2017 or 2016.

Convertible Notes

The Company completed a series of convertible note financings with certain investors beginning on November 1, 2014 and ending on February 18, 2015 (the Convertible Notes), whereby a total of $2.7 million was loaned to the Company, of which $2.0 million was loaned in 2015. Interest for the Convertible Notes compounded on a daily basis at a rate of 8 percent per annum. The Convertible Notes converted into shares of the Company’s Series A preferred stock upon close of the Series A preferred stock financing on March 31, 2015. The conversion equaled 125% of the unpaid principal plus unpaid accrued interest on the Convertible Notes.

At the time of their issuance, the Convertible Notes contained a conversion premium with regard to the conversion into the Series A preferred stock. The Company determined that the redemption feature under the Convertible Notes qualified as an embedded derivative and was separated from its debt host. The bifurcation of the embedded derivative from its debt host resulted in a discount to the Convertible Notes. The discount was amortized to interest expense over the term of the Convertible Notes using the straight‑line method. The embedded derivative was accounted for separately on a fair market value basis. The Company recorded the fair value changes of the premium conversion derivative associated with the Convertible Notes to interest expense that amounted to $0.4 million for the year ended December 31, 2015. As a result of their conversion into shares of Series A preferred stock on March 31, 2015 as described above, there were no Convertible Notes outstanding during 2017 or 2016.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies

Commitments and Contingencies

5. Commitments and Contingencies

Pfizer License Agreement

In April 2011, the Company and Pfizer Inc. (Pfizer) entered into an exclusive license agreement (the Pfizer Agreement) for the clinical product candidate gemcabene. In exchange for this worldwide exclusive right and license to certain patent rights to make, use, sell, offer for sale and import the clinical product gemcabene, the Company agreed to certain milestone and royalty payments on future sales (See Note 6 — License Agreement). As of December 31, 2017, there was sufficient uncertainty with regard to both the outcome of the clinical trials and the ability to obtain sufficient funding to support any of the cash milestone payments under the license agreement, and as such, no liabilities were recorded related to the license agreement.

Series A Preferred Stock Dividends

Holders of the Series A preferred stock were entitled to cumulative accruing dividends at a simple rate of 8% per year on the original issue price of the preferred stock of $6.70585 per share, as adjusted for the Reverse Stock Split. The dividends effectively accrued daily on each share of preferred stock. The dividends were payable upon the earliest to occur of (1) the date determined by the Board, (2) the liquidation of the Company (including a deemed liquidation event) or (3) the conversion or redemption of at least a majority of the outstanding shares of Series A preferred stock. If the board reasonably believed that the Company was not legally able to pay the dividends in cash at the payment date, or if elected by the majority of the Series A preferred stockholders or if issued in connection with an IPO, the dividends were to be paid in shares of common stock at the conversion price for the Series A preferred stock in effect at that time, which was the original issue price of the Series A preferred stock as adjusted from time to time for any stock dividends, combinations, splits or recapitalizations. Since the dividends were payable upon a contingent event, the Company did not record them in the accompanying financial statements as of December 31, 2015; however, cumulative unpaid dividends for the Series A preferred stock totaled $0.3 million as of December 31, 2015. On August 10, 2016, immediately prior to the closing of the IPO, the Company’s Series A preferred stock, together with accrued dividends thereon, converted into 827,205 shares of common stock, and as such, there were no cumulative unpaid dividends for the Series A preferred stock as of December 31, 2017 and 2016.

Other Agreements

Both cancellable and non-cancellable facility agreements were in place that provided for fixed monthly rent for the years ended December 31, 2017, 2016 and 2015. The total rent expense was $0.1 million, $58,000 and $23,000 for the years ended December 31, 2017, 2016 and 2015, respectively. In May 2016, the Company entered into a new lease agreement for its headquarters location, commencing in August 2016. The initial term of the agreement is 3 years with an initial monthly base rent of approximately $8,400 and increasing to approximately $8,900 during the last year of the lease term. In conjunction with entering into the new lease agreement, the Company cancelled its original Northville, Michigan lease agreement, as amended, effective August 31, 2016 and renegotiated a new cancellable lease agreement for limited use of office space in the Northville location that expired in September 2017 that had nominal rent.

Future minimum lease payments under fixed non-cancellable operating leases that expire on various dates through August 2019 consist of the following (in thousands):


	December 31,

2018	$	104
2019		71
Total	$	175

License Agreement	12 Months Ended
License Agreement	Dec. 31, 2017
License Agreement
License Agreement	6. License Agreement In April 2011, the Company entered into the Pfizer Agreement for a worldwide exclusive license to certain patent rights to make, use, sell, offer for sale and import the clinical product candidate gemcabene. In exchange for this license, the Company agreed to issue shares of its common stock to Pfizer representing 15% of the Company’s fully diluted capital at the close of its first arms‑length Series A financing, which occurred on March 31, 2015. The Company agreed to make milestone payments totaling up to $37 million upon the achievement of certain milestones, including the first regulatory submission in any country, regulatory approval in each of the United States, Europe and Japan, the first anniversary of the first regulatory approval in any country, and upon achieving certain aggregate sales levels of gemcabene or any product containing gemcabene. Future milestone payments under the Pfizer Agreement, if any, are not expected to begin for at least several years and extend over a number of subsequent years. The Company also agreed to pay Pfizer tiered royalties on a country‑by‑country basis based upon the annual amount of net sales, as specified in the Pfizer Agreement until expiration of the last valid claim of the licensed patent rights including any patent term extensions or supplemental protection certificates. Under the Pfizer Agreement, the Company is obligated to use commercially reasonable efforts to develop and commercialize gemcabene. On March 31, 2015, upon the closing of the Series A preferred stock financing, the Company issued 675,250 shares of its common stock, at a fair market value of $0.9 million, to Pfizer in connection with the first equity payment, pursuant to which Pfizer became the owner of more than 5% of the Company’s capital stock. The transaction was recorded as acquired in‑process research and development expenses based on the fair market value of the common shares issued since no processes or activities that would constitute a “business” were acquired and none of the rights and underlying assets acquired had alternative future uses or reached a stage of technological feasibility. None of the other milestone or royalty payments were triggered as of December 31, 2017. The Pfizer Agreement will expire upon expiration of the last royalty term. Either party may terminate the Pfizer Agreement for the other party’s uncured material breach or upon specified bankruptcy events. Pfizer may terminate the Pfizer Agreement if the Company or any of its sublicenses challenge the validity, enforceability or ownership of the licensed patents. Upon termination of the license agreement for cause by Pfizer, we must grant Pfizer a non-exclusive license to use any intellectual property rights arising from the development or commercialization of gemcabene. Additionally, Pfizer may revoke the license if the Company is unable to adequately commercialize gemcabene by April 2021. Pfizer has a non‑exclusive, sub licensable, royalty‑free right and license for non‑commercial research or development purposes to intellectual property rights relating to gemcabene that are developed by us after the effective date of the license with Pfizer.

Convertible Series A Preferred Stock	12 Months Ended
Convertible Series A Preferred Stock	Dec. 31, 2017
Convertible Series A Preferred Stock
Convertible Series A Preferred Stock	7. Convertible Series A Preferred Stock On March 31, 2015, the Company issued 745,637 shares of Series A preferred stock at a per share price of $6.70585, as adjusted for the Reverse Stock Split, or $5.0 million in the aggregate, consisting of $1.5 million in cash and $3.5 million representing 125% of the principal and accrued and unpaid interest on the Convertible Notes, all of which converted into shares of Series A preferred stock. On August 10, 2016, immediately prior to the closing of the IPO, the Company’s Series A preferred stock, together with accrued dividends thereon, converted into 827,205 shares of common stock. Prior to their conversion into shares of common stock, the Series A preferred stock had the following rights and preferences: Dividend Rights Dividends effectively accrued on a daily basis at a simple rate of 8% per annum on the sum of the original per share issue price. Dividends were effectively deemed declared daily and were payable upon the occurrence of certain events. In addition, the holders of the Series A preferred stock had rights to participate in common stock dividends, entitling holders of Series A preferred stock to a dividend payable at the same time as the dividend paid on common stock based on the number of shares of common stock each share of Series A preferred stock would convert into if such shares had converted on the record date. There were no dividends deemed payable and accrued as of December 31, 2017 or 2016 due to the conversion of the Series A preferred stock, together with accrued dividends thereon, on August 10, 2016 immediately prior to the closing of the IPO. Voting Rights Each share of Series A preferred stock was entitled to vote together with the common stock on all actions to be taken by the stockholders of the Company, based on the number of shares of common stock into which each share of Series A preferred stock could be converted. A separate vote of a majority of the outstanding shares of Series A preferred stock was required to (1) issue or authorize any class or series of equity securities or equivalents, (2) effect any transaction that results in a change in control, (3) change the principal business of the Company, enter new lines of business, or exit the current line of business, (4) issue of convertible debt above a certain threshold, or (5) materially sell, transfer, license, pledge or encumber technology or intellectual property. A management stock option plan approved by the board of directors, however, was not subject to a separate vote of the Series A preferred stockholders, but any subsequent increases to the authorized option pool were subject to approval by the Series A preferred stock holders via a separate vote. Liquidation Rights In the event of any liquidation, dissolution, or winding‑up of the Company, whether voluntary or involuntary, merger, consolidation or transaction in which over 50% of the Company’s voting power was transferred, or a sale, lease, transfer, exclusive license or disposition of all or substantially all of the assets of the Company, the Series A preferred stock holders were entitled to the assets of the Company legally available for distribution before any distribution or payment was made to the holders of common stock. The distribution amount would have been equal the original issue price of the Series A preferred stock (as adjusted for any stock dividends, combinations, splits or other recapitalizations since issuance), plus any accrued or declared but unpaid dividends thereon. After payment of the full liquidation preference to the Series A preferred stock holders, the remaining assets legally available for distribution would have been distributed to the holders of common stock and holders of the Series A preferred stock pro rata based on the number of shares of common stock each share of Series A preferred stock would convert into if such shares had converted immediately prior to such liquidation, dissolution, or winding‑up. Conversion Rights Shares of Series A preferred stock, at the option of the holder, could have been converted at any time into shares of common stock. The conversion rate would have been obtained by dividing the Series A preferred stock original issue price of $6.70585 per share, as adjusted for the Reverse Stock Split, by the conversion price per share in effect at the time of conversion. The Series A conversion price was initially equal to the original issue price, but could be adjusted on a broad‑based weighted average basis in connection with certain dilutive events. The Series A holder was also entitled to receive additional shares of common stock for any unpaid Series A dividends (whether or not declared). Shares of Series A preferred stock would have automatically converted into common stock based upon the then‑effective Series A conversion price upon the affirmative vote or consent of the holders of at least a majority of the outstanding shares of the Series A preferred stock, or at the closing of a firmly underwritten public offering. The conversion price for the Series A preferred stock was $6.70585 per share (as adjusted for the Reverse Stock Split) at the time of the conversion of the Series A preferred stock, together with accrued dividends thereon, immediately prior to the closing of the IPO on August 10, 2016. Redemption Rights The holders of at least 80% of the outstanding shares of Series A preferred stock could have required the Company to redeem all outstanding shares of Series A preferred stock at any time on or after December 31, 2020 at a redemption price equal to the greater of 150% of the liquidation preference of the Series A preferred stock or the fair market value per share plus any unpaid declared dividends. The liquidation preference of the Series A preferred stock was defined as an amount per share equal to $6.70585, as adjusted from time to time for any stock dividends, combinations, splits or recapitalizations, plus any accrued or declared but unpaid dividends thereon. The redemption value for redeemable preferred stock could have at times been based on fair market value. The assumptions used in calculating the estimated fair market value at each reporting period represented the Company’s best estimate, however, inherent uncertainties were involved. As a result, if factors or assumptions changed, the estimated fair value could have been materially different. The Company recognized changes in the redemption value immediately as they occurred and adjusted the carrying amount of the instrument to equal the redemption value at the end of each reporting period since it was probable that the instruments would have become redeemable. In the absence of retained earnings, these charges were recorded against additional paid‑in‑capital, if any, and then to accumulated deficit. The Company evaluated the Series A preferred stock and determined that it was considered an equity host under ASC 815, Derivatives and Hedging. In making this determination, the Company’s analysis followed the whole instrument approach that compared an individual feature against the entire Series A preferred stock instrument that included that feature. The Company’s analysis was based on a consideration of the economic characteristics and risks of the Series A preferred stock. More specifically, the Company evaluated all of the stated and implied substantive terms and features of the Series A preferred stock, including: (1) redemption features and their underlying exercisability, (2) existence of any protective covenants, (3) nature of dividends rights, (4) nature of voting rights, and (5) the existence and nature of any conversion rights. As a result of the above, the Company concluded that the Series A preferred stock represented an equity host, and as such, the redemption and/or conversion features of the Series A preferred stock were considered to be clearly and closely related to the associated Series A preferred stock host instrument. Accordingly, the redemption and/or conversion features of the Series A preferred stock were not considered an embedded derivative that required bifurcation.

Stockholders’ and Members' Deficit	12 Months Ended
Stockholders’ and Members' Deficit	Dec. 31, 2017
Stockholders’ and Members' Deficit
Stockholders’ and Members' Deficit	8. Stockholders’ Equity (Deficit) Common Stock The Company had 10,633,042 and 9,270,255 shares of its common stock issued and outstanding as of December 31, 2017 and 2016, respectively. Voting, dividend and liquidation rights of the holders of the common stock are subject to the Company’s articles of incorporation and corporate bylaws. On March 15, 2017, the Company issued and sold 1,324,256 units at a price of $9.47 per unit for gross proceeds of approximately $12.5 million in connection with the Private Placement. Each unit consisted of one share of the Company’s common stock and a warrant to purchase 0.75 shares of common stock. The issuance costs incurred through December 31, 2017 related to the Private Placement were $1.3 million. Warrants In connection with the Private Placement, the Company issued warrants to purchase an additional 993,204 shares of common stock. The warrants have a term of five years and were exercisable immediately upon issue with an exercise price equal to $10.40 per share. The warrants were classified as additional paid-in capital and recorded based on their relative fair value to the underlying common shares issued in the Private Placement. The fair market value of the warrants was approximately $4.9 million. The warrants were valued using the Black-Scholes method with the following assumptions: a risk-free interest rate of 2.0%, a contractual term of five years, zero dividend yield and a volatility factor of 65.1%. During the year ended December 31, 2017, 15,000 warrant shares were exercised. As of December 31, 2017, 978,204 warrant shares were outstanding. Dividend Rights Common stock holders are entitled to receive dividends at the sole discretion of the board of directors of the Company. There have been no dividends declared on common stock as of December 31, 2017. Voting Rights The holders of common stock are entitled to one vote for each share of common stock along with all other classes and series of stock of the Company on all actions to be taken by the stockholders of the Company, including actions that would amend the certificate of incorporation of the Company to increase the number of authorized shares of the common stock. Liquidation Rights In the event of any liquidation, dissolution, or winding‑up of the Company, the holders of common stock shall be entitled to share in the remaining assets of the Company available for distribution post preferential distributions made to holders of the Company’s preferred stock. There was no preferred stock outstanding as of December 31, 2017 and 2016. Deferred Offering Costs Costs incurred related to the Private Placement of $1.3 million through December 31, 2017 were offset against proceeds received from the Private Placement. In addition, IPO offering costs of $4.2 million, consisting of underwriting discounts and commissions, legal, accounting and other direct fees and costs, were initially capitalized and subsequently offset against the Company’s IPO proceeds upon the close of the offering in August 2016. There were $21,000 of deferred offering costs capitalized at December 31, 2017 related to a public offering of our common stock that was consummated in the first quarter of 2018 (See Note 16 — Subsequent Events). There were no deferred offering costs capitalized as of December 31, 2016.

Share-Based Compensation

12 Months Ended

Dec. 31, 2017

Share-Based Compensation

Share-Based Compensation

9. Share‑Based Compensation

Share-based compensation expense was included in general and administrative and research and development costs as follows in the accompanying statements of comprehensive loss (in thousands):


	Year Ended
	December 31,
	2017		2016		2015
General and administrative	$	4,091	$	1,166	$	284
Research and development		1,182		552		—
Total share-based compensation	$	5,273	$	1,718	$	284

Restricted Stock Awards

During the years ended December 31, 2017 and 2016, the Company did not grant any restricted stock awards (RSAs). During the year ended December 31, 2015, the Company granted an aggregate of 44,657 RSAs to certain of its employees, members of its board of directors and consultants subject to a 2014 Shareholders Agreement (the Agreement). The RSAs were subject to various vesting schedules and generally vested ratably over a six to twenty four month period coinciding with their respective service periods. During the years ended December 31, 2017, 2016 and 2015, no RSAs were forfeited.

A summary of RSA grant activity is as follows:


	Number of		Weighted-Average
	Shares		Fair Value (per share)

Non‑vested at December 31, 2014	994,613	$	0.09
Granted	44,567	$	0.21
Vested	(691,087)	$	0.09
Non‑vested at December 31, 2015	348,093	$	0.09
Granted	—	$	—
Vested	(344,084)	$	0.09
Non‑vested at December 31, 2016	4,009	$	0.21
Granted	—	$	—
Vested	(4,009)	$	0.21
Non‑vested at December 31, 2017	—	$	—

The grant‑date fair value of the RSAs issued during the year ended December 31, 2015 was $9,000. Grant date fair market value for the RSAs issued prior to the IPO was based on traditional valuation techniques and methods in determining the fair value of the Company’s equity as a private company including market, income, and cost valuation approaches. A number of objective and subjective factors were considered including contemporaneous and retrospective valuations of its common stock performed by an unrelated valuation specialist, sales of the Company’s convertible preferred stock to unrelated third parties, valuations of comparable peer public companies, the lack of liquidity of the Company’s capital stock and general and industry‑specific economic outlook. The fair value of the Company’s common stock was determined by the Company’s board of directors prior to the IPO.

Stock Options

In April 2015, the Company adopted a 2015 Equity Incentive Plan (the 2015 Plan) under which 320,615 shares of the Company’s common stock were reserved for issuance to employees, directors and consultants. The 2015 Plan permits the grant of incentive and non‑statutory stock options, appreciation rights, restricted stock, restricted stock units, performance stock and cash awards, and other stock‑based awards.

Amendment and Restatement of 2015 Equity Incentive Plan

In April 2016 the Company’s board of directors approved the Company’s amended and restated 2015 Plan (the A&R 2015 Plan). The A&R 2015 Plan became effective immediately upon the execution and delivery of the underwriting agreement related to the IPO. The A&R 2015 Plan provides for the grant of stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance-based stock awards and other forms of equity awards, as well as performance cash awards. The Company initially reserved 2,400,000 shares of common stock for issuance under the A&R 2015 Plan.

During the years ended December 31, 2017, 2016 and 2015, the Company granted an aggregate of 150,500, 1,825,700 and 305,278, respectively, of stock options under the A&R 2015 Plan or the 2015 Plan to its officers, directors, employees and consultants, generally vesting over a three or four-year period.

Inducement Plan

In September 2016 the Company’s board of directors approved the Company’s Inducement Plan (the Inducement Plan). The Company initially reserved 300,000 shares of its common stock to be used exclusively for grants of awards to individuals who were not previously employees or directors of the Company, as an inducement material to the individual’s entry into employment with the Company within the meaning of Rule 5635(c)(4) of the NASDAQ Listing Rules. The Plan was approved by the Company’s board of directors without stockholder approval pursuant to Rule 5635(c)(4), and the terms and conditions of the Plan are substantially similar to the Company’s stockholder-approved A&R 2015 Plan. During the years ended December 31, 2017 and 2016, 98,000 and 198,000 stock options to newly-hired officers and employees were granted, respectively, under the Inducement Plan, generally vesting over a four-year period.

The following table summarizes the Company’s stock option plan activity for the years ended December 31, 2017, 2016 and 2015 as follows:


				Weighted‑
		Weighted		Average
		Average		Remaining	Aggregate
	Number of	Exercise		Contractual	Intrinsic
	Options	Price		Term (years)	Value(1)

Outstanding at December 31, 2014	—	$	—	—	$	—
Granted	305,278	$	2.42	—		—
Exercised	(2,436)	$	1.34	—		—
Forfeited/Cancelled	—	$	—	—		—
Outstanding at December 31, 2015	302,842	$	2.43	9.60	$	1,031,000
Granted	2,023,700	$	10.07	—		—
Exercised	—	$	—	—		—
Forfeited/Cancelled	(83,742)	$	9.12	—		—
Outstanding at December 31, 2016	2,242,800	$	9.07	9.48	$	(2,759,000)
Granted	248,500	$	12.24	—		—
Exercised	(23,910)	$	1.92	—		—
Forfeited/Cancelled	(3,250)	$	1.34	—		—
Outstanding at December 31, 2017	2,464,140	$	9.46	8.58	$	(3,715,000)
Vested and exercisable at December 31, 2017	1,204,533	$	8.53	8.45	$	(699,000)
Vested and expected to vest at December 31, 2017	2,464,140	$	9.46	8.58	$	(3,715,000)

⁽¹⁾

The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of our common stock as of December 31, 2017, 2016 and 2015 of $7.95, $7.84 and $5.83 per share, respectively.

The weighted average fair value per share of options granted during the years ended December 31, 2017, 2016 and 2015 was $7.35, $6.37 and $1.50, respectively.

The Company measures the fair value of stock options with service‑based and performance‑based vesting criteria to employees, consultants and directors on the date of grant using the Black‑Scholes option pricing model. The fair value of equity instruments issued to non‑employees is re‑measured as the award vests. The Company does not have history to support a calculation of volatility and expected term. As such, the Company has used a weighted‑average volatility considering the volatilities of several guideline companies.

For purposes of identifying similar entities, the Company considered characteristics such as industry, length of trading history, and stage of life cycle. The assumed dividend yield was based on the Company’s expectation of not paying dividends in the foreseeable future. The average expected life of the options was determined based on the mid‑point between the vesting date and the end of the contractual term according to the “simplified method” as described in Staff Accounting Bulletin 110. The risk‑free interest rate is determined by reference to implied yields available from U.S. Treasury securities with a remaining term equal to the expected life assumed at the date of grant. The Company records forfeitures when they occur.

The weighted‑average assumptions used in the Black‑Scholes option‑pricing model are as follows:


	Year Ended
	December 31,
	2017			2016			2015

Expected stock price volatility		65.8	%		71.4	%		71.0	%
Expected life of options (years)		5.9			6.0			5.5
Expected dividend yield		0	%		0	%		0	%
Risk free interest rate		2.0	%		1.2	%		1.7	%

During the years ended December 31, 2017, 2016 and 2015, 861,645, 276,248 and 104,907 stock options vested, respectively. The weighted average fair value per share of options vesting during the years ended December 31, 2017, 2016 and 2015 was $9.45, $4.59 and $1.05, respectively. During the years ended December 31, 2017 and 2016, 3,250 and 83,742 stock options were forfeited, respectively. During the year ended December 31, 2015, no stock options were forfeited. As of December 31, 2017, 212,329 shares were available for future issuance under the A&R 2015 and Inducement Plans.

Under the A&R 2015 Plan, common shares reserved automatically increase on January 1st of each year, for a period of 10 years commencing on January 1, 2017 and ending on (and including) January 1, 2026, to an amount equal to 20% of the Company’s fully-diluted shares as of December 31st of the preceding calendar year. Notwithstanding the foregoing, the Company’s board of directors may act prior to January 1st of a given year to provide that there will be no January 1st increase in the shares reserved for such year, or that the increase in shares reserved for such year will be a lesser number of shares than what would have otherwise been allowed to occur under the provision. Effective January 1, 2018, 415,077 shares were added to the AR 2015 Plan under the share reserve provision. There were no shares added to the A&R 2015 Plan under the share reserve provision during fiscal year 2017.

Unrecognized share‑based compensation cost for the RSAs and stock options issued under the Company’s 2014 Shareholders Agreement, A&R 2015 Plan and Inducement Plan was $6.9 million as of December 31, 2017. All of the unrecognized compensation cost was related to the stock options. The non‑employee portion of the unrecognized compensation cost was estimated utilizing the Company’s fair market value for its common stock as of December 31, 2017. The unrecognized share‑based expense is expected to be recognized over a weighted average period of 2.3 years.

Adoption of 2016 Employee Stock Purchase Plan

In April 2016 the Company’s board of directors approved the 2016 Employee Stock Purchase Plan (the ESPP) in order to enable eligible employees to purchase shares of the Company’s common stock at a discount following the effective date of the IPO. The Company’s stockholders also approved the ESPP in April 2016 and the ESPP became effective immediately upon the execution and delivery of the underwriting agreement related to the IPO. The Company initially reserved 150,000 shares of common stock for issuance under the ESPP. As of December 31, 2017, no shares were purchased under the ESPP.

Net Loss Per Common Share

12 Months Ended

Dec. 31, 2017

Net Loss Per Common Share

Net Loss Per Common Share

10. Net Loss Per Common Share

Basic earnings or loss per share of common stock is computed by dividing net loss by the weighted average number of shares of common stock outstanding during the period. The holders of the Series A preferred stock had rights to participate in common stock dividends, entitling the holders of Series A preferred stock to a dividend payable at the same time and rate per share as the dividend paid on common stock based the number of shares of common stock each share of Series A preferred stock would have converted into if such shares had converted on the record date. The Series A preferred stock, however, did not have a contractual obligation to share in the losses of the Company, and as such, no losses were allocated to the Series A preferred stock for the purposes of the basic loss per share calculation while they were outstanding.

Diluted earnings or loss per share of common stock is computed similarly to basic earnings or loss per share except the weighted average shares outstanding are increased to include additional shares from the assumed exercise of any common stock equivalents, if dilutive. The Company’s RSAs, stock options, warrants, shares of Series A preferred stock, Convertible Notes and Interim Notes are considered common stock equivalents while outstanding for this purpose. Diluted earnings is computed utilizing the treasury method for the RSAs, stock options and warrants, and in the case of the Series A preferred stock, either the two‑class method or the if‑converted method, whichever was more dilutive. Diluted earnings with respect to the Convertible Notes and Interim Notes utilized the if‑converted method, but was not applicable during the years ended December 31, 2017, 2016 and 2015 as no conditions required for conversion had occurred during these periods while the instruments were outstanding. No incremental common stock equivalents were included in calculating diluted loss per share because such inclusion would be anti‑dilutive given the net loss reported for the years ended December 31, 2017, 2016 and 2015. The following table sets forth the computation of basic and diluted loss per share as of December 31, 2017, 2016 and 2015 (in thousands, except share and per share amounts):


	Year Ended
	2017		2016		2015
Numerator:
Net loss	$	(33,415)	$	(14,586)	$	(9,029)
Adjustment to redemption value on Series A convertible preferred stock		—		(366)		(2,968)
Premium upon substantial modification of convertible notes with certain stockholders		—		—		(1,047)
Net loss attributed to common stock holders	$	(33,415)	$	(14,952)	$	(13,044)
Denominator:
Basic and diluted weighted average common shares outstanding		10,349,136		5,809,396		2,875,053
Basic and diluted net loss per share	$	(3.23)	$	(2.57)	$	(4.54)

The following potential common shares were not considered in the computation of diluted net loss per share as their effect would have been anti‑dilutive:


	Year Ended
	2017	2016	2015
Stock options	2,464,140	2,242,800	302,842
Restricted stock awards	—	4,009	348,093
Warrants	978,204	—	—
Series A	—	—	745,637
Convertible notes	—	—	828,751

Fair Value Measurements

12 Months Ended

Dec. 31, 2017

Fair Value Measurements

Fair Value Measurements

11. Fair Value Measurements

The Company follows accounting guidance that emphasizes that fair value is a market‑based measurement, not an entity specific measurement. Fair value is defined as “the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.” Fair value measurements are defined on a three level hierarchy:

Level 1 inputs: Unadjusted quoted prices for identical assets or liabilities in active markets;

Level 2 inputs: Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, weather directly or indirectly, for substantially the full term of the asset or liability;

Level 3 inputs: Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability in which there is little, if any, market activity for the asset or liability at the measurement date.

As of December 31, 2017 and 2016, the fair values of cash and cash equivalents, other assets, accounts payable and accrued liabilities approximated their carrying values because of the short‑term nature of these assets or liabilities. The estimated fair value of the Company’s Interim Notes prior to conversion upon the close of the IPO, and Term Loan was based on amortized cost which was deemed to approximate fair value. The derivative liability associated with the conversion premium on the Interim Notes was based on cash flow models discounted at current implied market rates evidenced in recent arms‑length transactions representing expected returns by market participants for similar instruments which were based on Level 3 inputs.

The following table provides a roll‑forward of the Company’s premium conversion derivative liabilities measured at fair value on a recurring basis using unobservable level 3 inputs (in thousands):


	For the Year Ended December 31,
	2017		2016		2015
Balance as of beginning of period	$	—	$	345	$	73
Issuance of underlying convertible notes		—		505		842
Change in fair value of premium conversion derivative		—		(850)		297
Reversal of premium conversion derivative associated with note extinguishment		—		—		(182)
Redemption of underlying convertible notes		—		—		(685)
Balance as of end of period	$	—	$	—	$	345

There were no financial instruments measured on a recurring basis as of December 31, 2017 and 2016 and on a non‑recurring basis for any of the periods presented.

- 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

Income Taxes

12 Months Ended

Dec. 31, 2017

Income Taxes

Income Taxes

12. Income Taxes

On December 22, 2017, the Tax Cuts and Jobs Act (the TCJA), which significantly modified U.S. corporate income tax law, was signed into law by President Trump. The TCJA contains significant changes to corporate income taxation, including but not limited to the reduction of the corporate income tax rate from a top marginal rate of 35% to a flat rate of 21%, limitation of the tax deduction for interest expense to 30% of earnings (except for certain small businesses), limitation of the deduction for net operating losses to 80% of current year taxable income and generally eliminating net operating loss carrybacks, allowing net operating losses to carryforward without expiration, one-time taxation of offshore earnings at reduced rates regardless of whether they are repatriated, elimination of U.S. tax on foreign earnings (subject to certain important exceptions), immediate deductions for certain new investments instead of deductions for depreciation expense over time, and modifying or repealing many business deductions and credits (including changes to the orphan drug tax credit and changes to the deductibility of research and experimental expenditures that will be effective in the future). Notwithstanding the reduction in the corporate income tax rate, the overall impact of the new federal tax law is uncertain, including to what extent various states will conform to the newly enacted federal tax law.

The Company has recorded the necessary provisional adjustments in the financial statements in accordance with its current understanding of the TCJA and guidance currently available as of this filing and recorded a provisional reduction of $6.8 million to its gross deferred tax assets in the fourth quarter of 2017, the period in which the legislation as enacted. The provisional reduction was fully offset by an equal reduction in the Company’s valuation allowance given the Company’s historical net losses, resulting in no net income tax expense being recorded. The Company may adjust these provisional amounts in future periods if its interpretation of the TCJA changes or as additional guidance becomes available. Any subsequent adjustment to these amounts is not expected to have a significant impact due to the valuation allowance.

The effective tax rate for the years ended December 31, 2017, 2016 and 2015 was zero percent. A reconciliation of income tax computed at the statutory federal income tax rate to the provision (benefit) for income taxes included in the accompanying statements of comprehensive loss is as follows:


	For the Year Ended December 31,
	2017		2016		2015
Income tax (benefit) provision at federal statutory rate	(34.0)	%	(34.0)	%	(34.0)	%
Valuation allowance	21.0		40.2		38.2
U.S. tax reform	20.2		—		—
State income tax, net of federal benefit	(4.1)		(4.7)		(4.0)
Convertible notes	—		1.1		0.6
Research credits	(3.6)		(4.0)		(1.1)
Other	0.5		1.4		0.3
Effective tax rate	—	%	—	%	—	%

Significant components of the Company’s deferred tax assets and liabilities are summarized in the tables below as of (in thousands):


	Year Ended December 31,
Deferred tax assets:	2017		2016
Federal and state operating loss carryforwards	$	3,349	$	2,289
Research and development costs deferral election		8,881		5,254
Acquired intangibles		235		351
Accruals		—		13
Term loan		33		—
Charitable contributions		14		12
Stock-based compensation		1,722		633
Research and development credit carryforwards		1,947		768
		16,181		9,320
Valuation allowance		(16,181)		(9,320)
Total deferred tax assets, net of valuation allowance		—		—
Deferred tax liabilities:
Total deferred tax liabilities		—		—
Net deferred tax assets	$	—	$	—

As of December 31, 2017 and 2016, the Company had gross deferred tax assets of approximately $16.2 million and $9.3 million, respectively. Realization of the deferred assets is primarily dependent upon future taxable income, if any, the amount and timing of which are uncertain. The Company has had significant pre‑tax losses since its inception. The Company has not yet generated revenues and faces significant challenges to becoming profitable. Accordingly, the net deferred tax assets have been fully offset by a valuation allowance of $16.2 million and $9.3 million as of December 31, 2017 and 2016, respectively. U.S. net deferred tax assets will continue to require a valuation allowance until the Company can demonstrate their realizability through sustained profitability or another source of income.

As of December 31, 2017 and 2016, the tax effect of the Company’s federal net operating loss carryforwards was approximately $2.8 million and $2.1 million, respectively. The Company had federal research credit carryforwards as of December 31, 2017 and 2016 of approximately $1.9 million and $0.7 million, respectively. The federal net operating loss and tax credit carryforwards will begin to expire in 2034 if not utilized. As of December 31, 2017 and 2016, the Company had state net operating loss carryforwards with a tax effect of approximately $0.6 million and $0.2 million, respectively. The Company had state research credit carryforwards of $45,000 and $24,000 as of December 31, 2017 and 2016, respectively. The state net operating loss carryforwards will begin to expire in 2026, if not utilized, and the state research credit carryforwards will begin to expire in 2023 if not utilized. Recent tax reform legislation has significantly revised the rules applicable to the utilization of net operating losses for tax years either beginning or ending after January 1, 2018.

Utilization of the net operating loss carryforwards and credits may be subject to a substantial annual limitation due to the ownership change limitations provided by Section 382 of the Internal Revenue Code of 1986, as amended, and similar state provisions. Generally, in addition to certain entity reorganizations, the limitation applies when one or more “5-percent shareholders” increase their ownership, in the aggregate, by more than 50 percentage points over a 36‑month time period testing period, or beginning the day after the most recent ownership change, if shorter. The annual limitation may result in the expiration of net operating losses and credits before utilization.

The Company recognizes interest and/or penalties related to uncertain tax positions in income tax expense. There were no uncertain tax positions as of December 31, 2017 and 2016, and as such, no interest or penalties were recorded to income tax expense.

The Company’s corporate returns are subject to examination for the 2014, 2015 and 2016 tax years for federal income tax purposes and subject to examination for the 2015 and 2016 tax years in various state jurisdictions. Prior to these periods, the Company filed partnership returns, resulting in its income being passed through to its members.

Quarterly Data

12 Months Ended

Dec. 31, 2017

Supplementary Data — Quarterly Financial Data (unaudited)

Supplementary Data — Quarterly Financial Data (unaudited)

13. Supplementary Data — Quarterly Financial Data (unaudited)

The following table presents certain unaudited quarterly financial information for each of the eight fiscal quarters in the period ended December 31, 2017. This quarterly information has been prepared on the same basis as the audited financial statements and includes all adjustments, consisting only of normal recurring adjustments, necessary for a fair presentation of the information for the periods presented. The results for these quarterly periods are not necessarily indicative of the operating results for a full year or any future period.


	Three Months Ended
	December 31,		September 30,		June 30,		March 31,
	2017		2017		2017		2017
	(in thousands, except per share amounts)
Operating expenses:
General and administrative	$	1,487	$	2,050	$	4,678	$	2,223
Research and development		5,080		6,489		5,837		5,280
Total operating expenses		6,567		8,539		10,515		7,503
Loss from operations		(6,567)		(8,539)		(10,515)		(7,503)
Interest (expense) income		(179)		(132)		13		12
Other expense		—		—		—		(5)
Loss before income taxes		(6,746)		(8,671)		(10,502)		(7,496)
Provision (benefit) for income taxes		—		—		—		—
Net loss		(6,746)		(8,671)		(10,502)		(7,496)
Other comprehensive loss, net of tax		—		—		—		—
Comprehensive loss	$	(6,746)	$	(8,671)	$	(10,502)	$	(7,496)
Net loss per share:
Basic and diluted (A)	$	(0.63)	$	(0.82)	$	(0.99)	$	(0.79)

	Three Months Ended
	December 31,		September 30,		June 30,		March 31,
	2016 (B)		2016 (B)		2016		2016
	(in thousands, except per share amounts)
Operating expenses:
General and administrative	$	2,389	$	1,466	$	1,051	$	1,050
Research and development		4,839		1,936		789		1,176
Total operating expenses		7,228		3,402		1,840		2,226
Loss from operations		(7,228)		(3,402)		(1,840)		(2,226)
Interest income (expense)		13		(475)		449		127
Other income (expense)		1		(1)		—		(4)
Loss before income taxes		(7,214)		(3,878)		(1,391)		(2,103)
Provision (benefit) for income taxes		—		—		—		—
Net loss		(7,214)		(3,878)		(1,391)		(2,103)
Other comprehensive loss, net of tax		—		—		—		—
Comprehensive loss	$	(7,214)	$	(3,878)	$	(1,391)	$	(2,103)
Net loss	$	(7,214)	$	(3,878)	$	(1,391)	$	(2,103)
Adjustment to redemption value on Series A convertible preferred stock		—		(67)		(150)		(149)
Net loss attributable to common stockholders	$	(7,214)	$	(3,945)	$	(1,541)	$	(2,252)
Net loss per share:
Basic and diluted (A)	$	(0.78)	$	(0.56)	$	(0.42)	$	(0.65)

^(A)

Net loss per share for the year may not equal the sum of the four historical quarters loss per share due to changes in weighted-average shares outstanding.

^(B)

Activity for the quarterly periods ending December 31, 2016 reflects activity both before and after the IPO depicting a ramp-up of research and development expenses given the additional IPO proceeds and an increase in general and administrative expenses attributed to becoming a public company.

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2017
Related Party Transactions
Related Party Transactions	14. Related Party Transactions The Company rented an office in Northville, Michigan from an LLC owned by two officers under short‑term agreements during the years ended December 31, 2017, 2016 and 2015. The original facility lease, as amended, was cancelled and replaced with a cancellable lease agreement in August 2016 for limited use of office space in the same Northville location. The new lease agreement became effective in August 2016 and expired in September 2017. Rent expense under the related party agreements was nominal during the year ended December 31, 2017 and was $21,000 and $23,000 during the years ended December 31, 2016 and 2015, respectively. During the first quarter of 2015, the Company issued $2.0 million of additional Convertible Notes (the 2015 Notes) as part of the Convertible Notes described in Note 4 — Debt. The 2015 Notes included four notes in the aggregate of $0.3 million issued to investors who were related to one board member and three officers of the Company. On March 31, 2015, all of the Convertible Notes (including the 2015 Notes) were converted into 516,421 shares of Series A preferred stock. The conversion included a total of 68,649 shares of Series A preferred stock issued to two officers of the Company, and 63,967 shares of Series A preferred stock issued to investors related to one board member and three officers of the Company. During the third quarter of 2015, the Company issued $2.8 million of Interim Notes as described in Note 4 — Debt. Such Interim Notes included five notes issued to two officers and three board members (or entities they control) in the amount of $0.5 million. In addition, such Interim Notes included four notes to investors who were related to three of the Company’s officers and to one of the Company’s key employees in the amount of $0.3 million. In December 2015, the Company issued an additional $2.7 million of Interim Notes, as described in Note 4 — Debt, which included six notes issued to two officers and four board members in the amount of $0.6 million. The December 2015 Interim Note issuances also included five notes to investors who were related to three of the Company’s officers in the amount of $0.2 million. In February 2016, the Company issued an additional $0.2 million of Interim Notes, as described in Note 4 — Debt, which included two notes issued to two board members (or entities they control) in the amount of $81,000. The February 2016 Interim Note issuances also included a $20,000 note to an investor who is related to an officer of the Company. In April 2016, the Company issued an additional $5.0 million of Interim Notes, as described in Note 4 — Debt, which included two notes to investors who were related to two of the Company’s officers in the aggregate amount of $0.2 million. The April 2016 Interim Notes issuances also included three notes to investors who were related to three of the Company’s directors in the aggregate amount of $2.3 million. The IPO included 154,450 shares sold to 5 officers and 3 board members, totaling $1.5 million. In addition, 500,000 shares were sold to 1 investor who is related to 1 of the Company’s directors, totaling $5.0 million, and 47,000 shares totaling $0.5 million were sold to 14 investors who are related to 5 officers of the Company. The Private Placement included 56,678 units sold to three board members, for aggregate proceeds totaling approximately $0.5 million, and 52,798 units sold to one investor who was related to one board member, for proceeds totaling approximately $0.5 million.

Defined Contribution Plan	12 Months Ended
Defined Contribution Plan	Dec. 31, 2017
Defined Contribution Plan
Defined Contribution Plan	15. Defined Contribution Plan The Company adopted a 401(k) defined contribution plan on September 5, 2017, effective as of January 1, 2017, for all employees over age 21. Employees can defer up to 100% of their compensation through payroll withholdings into the plan subject to federal law limits. Effective January 1, 2018, the Company will make matching contributions on deferrals at 100% of deferrals up to 3% of one’s contributions and 50% on deferrals over 3%, but not exceeding 5% of one’s contributions in order to satisfy certain non-discrimination tests required by the Internal Revenue Code. Employee contributions and any employer matching contributions made to satisfy certain non-discrimination tests required by the Internal Revenue Code are 100% vested upon contribution. Discretionary employer matches vest over a six-year period beginning on the second anniversary of an employee’s date of hire. No matching contribution obligations were recorded by the Company as of December 31, 2017.

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2017
Subsequent Events
Subsequent Events	16. Subsequent Events In the first quarter of 2018, the Company completed an underwritten public offering of 3,592,858 shares of common stock, including 450,000 shares of our common stock purchased by the underwriters upon the partial exercise of their overallotment option, at the public offering price of $7.00 per share. The Company received net proceeds of approximately $23.0 million after deducting underwriting discounts and commissions and offering expenses. The offering included 14,286 shares sold to 1 officer, for aggregate proceeds totaling approximately $0.1 million and 71,429 shares sold to 1 investor who is related to 1 officer and board member, for proceeds totaling approximately $0.5 million.

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS

12 Months Ended

Dec. 31, 2017

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS


SCHEDULE II
VALUATION AND QUALIFYING ACCOUNTS

	Beginning		Additions						Ending
	Balance of		Charged to		Charged to				Balance of
Description	Period		Costs and Expenses		Paid in Capital		Releases		Period

(in thousands)

For the Year Ended December 31, 2015
Valuation allowance for deferred taxes	$	72	$	3,447	$	138	$	—	$	3,657
For the Year Ended December 31, 2016
Valuation allowance for deferred taxes	$	3,657	$	5,937	$	(274)	$	—	$	9,320
For the Year Ended December 31, 2017
Valuation allowance for deferred taxes	$	9,320	$	6,861	$	—	$	—	$	16,181

Summary of Significant Accounting Policies (Policies)	12 Months Ended
Summary of Significant Accounting Policies (Policies)	Dec. 31, 2017
Summary of Significant Accounting Policies
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of 90 days or less at the time of deposit to be cash equivalents. The Company invests excess cash in readily available checking and savings accounts and highly liquid investments in money market accounts.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s financial instruments include principally cash and cash equivalents, other current assets, accounts payable, accrued liabilities and debt. The carrying amounts for these financial instruments reported in the balance sheets approximate their fair values. See Note 11 — Fair Value Measurements, for further discussion of fair value.
General and Administrative Expenses	General and Administrative Expenses General and administrative expenses consist primarily of personnel‑related costs, including salaries and share‑based compensation costs, for personnel in functions not directly associated with research and development activities. Other significant costs include legal fees related to intellectual property and corporate matters and professional fees for accounting and other services.
Research and Development Expenses	Research and Development Expenses Research and development expenses consist of costs incurred in performing research and development activities, including compensation for research and development employees, costs associated with preclinical studies and trials, regulatory activities, manufacturing activities to support clinical activities, license fees, non‑legal patent costs, fees paid to external service providers that conduct certain research and development, clinical costs and an allocation of overhead expenses. Research and development costs are expensed as incurred.
Acquired In-Process Research and Development Expenses	Acquired In‑Process Research and Development Expenses The Company includes costs to acquire or in‑license product candidates in acquired in‑process research and development expenses. The Company has acquired the right to develop and commercialize its product candidate gemcabene. These costs are immediately expensed provided that the payments do not also represent processes or activities that would constitute a “business” as defined under GAAP or provided that the product candidate has not achieved regulatory approval for marketing and absent obtaining such approval, has no alternative future use. Royalties owed on future sales of any licensed product will be expensed in the period the related revenues are recognized.
Income Taxes	Income Taxes The Company utilizes the liability method of accounting for income taxes as required by Accounting Standards Codification (ASC) 740, Income Taxes. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and the tax basis of assets and liabilities and are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse. Currently, there is no provision for income taxes, as the Company has incurred operating losses to date, and a full valuation allowance has been provided on the net deferred tax assets. MLT was treated as a partnership for federal and state income tax purposes. Accordingly, no provision was made for income taxes for periods prior to November 1, 2014, since the Company’s net loss (subject to certain limitations) was passed through to the income tax returns of its members. Upon incorporation on October 30, 2014, the Company became taxed as a corporation.
Share-Based Compensation	Share‑Based Compensation The Company accounts for share‑based compensation in accordance with the provisions of ASC 718, Compensation — Stock Compensation (ASC 718). Accordingly, compensation costs related to equity instruments granted are recognized at the grant‑date fair value. The Company records forfeitures when they occur. Share‑based compensation arrangements to non‑employees are accounted for in accordance with the applicable provisions of ASC 718 and ASC 505, Equity, using a fair value approach. The compensation costs of these arrangements are subject to re‑measurement as the equity instruments vest and are recognized as expense over the related service period (typically the vesting period of the awards).
Common Stock Valuation	Common Stock Valuation Due to the absence of an active market for the Company’s common stock prior to the close of the IPO, the Company utilized methodologies in accordance with the framework of the American Institute of Certified Public Accountants’ Technical Practice Aid, Valuation of Privately‑Held Company Equity Securities Issued as Compensation, to estimate the fair value of its common stock. The valuation methodology included estimates and assumptions that required the Company’s judgment. These estimates and assumptions included a number of objective and subjective factors, including external market conditions affecting the biopharmaceutical industry sector, and the likelihood of achieving a liquidity event, such as an initial public offering or sale. Significant changes to the key assumptions used in the valuations could have resulted in different fair values of common stock at each valuation date.
Convertible Preferred Stock	Convertible Preferred Stock On March 31, 2015, the Company issued 745,637 shares of Series A convertible preferred stock (the Series A preferred stock). On August 10, 2016, immediately prior to the closing of the IPO, the Company’s Series A preferred stock, together with accrued dividends thereon, converted into 827,205 shares of common stock. The Series A preferred stock prior to conversion was classified outside of permanent equity, in mezzanine equity, on the Company’s balance sheet. The Company initially records preferred stock that may be redeemed at the option of the holder, or based on the occurrence of events outside of the Company’s control, at the value of the proceeds received. Subsequently, if it is probable that the preferred stock will become redeemable, the Company recognizes changes in the redemption value immediately as they occur and adjusts the carrying amount of the instrument to equal the redemption value at the end of each reporting period. If it is not probable that the preferred stock will become redeemable, the Company does not adjust the carrying value. In the absence of retained earnings, these charges are recorded against additional paid‑in‑capital, if any, and then to accumulated deficit See Note 7 — Convertible Series A Preferred Stock for further discussion. As a result of their conversion to common stock on August 10, 2016 as described above, no shares of Series A preferred stock were outstanding as of December 31, 2017 and 2016.
Segment Information	Segment Information Operating segments are components of an enterprise for which separate financial information is available and is evaluated regularly by the Company’s chief operating decision maker in deciding how to allocate resources and assessing performance. The Company’s chief operating decision maker is its Chief Executive Officer. The Company’s Chief Executive Officer views the Company’s operations and manages its business in one operating segment, which is the business of development and commercialization of therapeutics for the treatment of dyslipidemia, a serious medical condition that increases the risk of life threatening cardiovascular disease and NAFLD/NASH. Accordingly, the Company has a single reporting segment.
Jumpstart Our Business Startups Act Accounting Election	Jumpstart Our Business Startups Act Accounting Election As an emerging growth company under the Jumpstart Our Business Startups Act (JOBS Act), the Company is eligible to take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not emerging growth companies. The Company has irrevocably elected not to avail itself of this exemption and, therefore, will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued ASU 2014‑09, Revenue from Contracts with Customers — Topic 606, which supersedes the revenue recognition requirements in FASB ASC 605. The new guidance primarily states that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. In January 2017 and September 2017, the FASB issued several amendments to ASU 2014‑09, including updates stemming from SEC Accounting Staff Announcement in July 2017. The amendments and updates included clarification on accounting for principal versus agent considerations (i.e., reporting gross versus net), licenses of intellectual property and identification of performance obligations. These amendments and updates do not change the core principle of the standard, but provide clarity and implementation guidance. The Company will adopt this standard on January 1, 2018 and selected the modified retrospective transition method. The Company will modify its accounting policies to reflect the requirements of this standard however, the planned adoption will not affect the Company’s financial statements and related disclosures for these periods or future periods until the Company generates revenues. In January 2016, the FASB issued ASU No. 2016‑01, Financial Instruments — Overall: Recognition and Measurement of Financial Assets and Financial Liabilities. The guidance affects the accounting for equity investments, financial liabilities under the fair value option and the presentation and disclosure requirements of financial instruments. The guidance is effective in the first quarter of fiscal 2019. Early adoption is permitted for the accounting guidance on financial liabilities under the fair value option. The Company is currently evaluating the impact of the new guidance on its financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) and subsequently amended the guidance relating largely to transition considerations under the standard in January 2017. The objective of this update is to increase transparency and comparability among organizations by recognizing lease assets and lease liabilities on the balance sheet and disclosing key information about leasing arrangements. This ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those annual periods and is to be applied utilizing a modified retrospective approach. The Company is currently evaluating the new guidance to determine the impact it may have on its financial statements. In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash. The objective of this ASU is to eliminate the diversity in practice related to the classification of restricted cash or restricted cash equivalents in the statement of cash flows. For public business entities, this ASU is effective for annual and interim reporting periods beginning after December 15, 2017, with early adoption permitted. The amendments in this update should be applied retrospectively to all periods presented. The Company will adopt this standard on January 1, 2018 and will not have a material impact on the Company’s financial statements. In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting (ASU 2016-09), which provides guidance about which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. This pronouncement is effective for annual reporting periods beginning after December 15, 2017. The Company will adopt this standard on January 1, 2018 and will not have a material impact on the Company’s financial statements. In July 2017, the FASB issued ASU No. 2017-11, Earnings Per Share, Distinguishing Liabilities from Equity and Derivatives and Hedging, which changes the accounting and earnings per share for certain instruments with down round features. The amendments in this ASU should be applied using a cumulative-effect adjustment as of the beginning of the fiscal year or retrospective adjustment to each period presented and is effective for annual periods beginning after December 15, 2018, and interim periods within those periods. The Company is currently evaluating the requirements of this new guidance and has not yet determined its impact on the Company’s financial statements. On December 22, 2017 the SEC staff issued Staff Accounting Bulletin 118 (SAB 118), which provides guidance on accounting for the tax effects of the Tax Cuts and Jobs Act (the TCJA). SAB 118 provides a measurement period that should not extend beyond one year from the enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the TCJA for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the TCJA is incomplete but for which they are able to determine a reasonable estimate, it must record a provisional amount in the financial statements. Provisional treatment is proper in light of anticipated additional guidance from various taxing authorities, the SEC, the FASB, and even the Joint Committee on Taxation. If a company cannot determine a provisional amount to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the TCJA. The Company has applied this guidance to its financial statements

Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Accrued Liabilities

Schedule of accrued liabilities

Accrued liabilities consist of the following (in thousands):


	As of December 31,
	2017		2016
Accrued compensation and other payroll liabilities	$	306	$	706
Legal costs		91		54
Accrued interest		38		—
Other research and development expenses		522		1,259
Other general and administrative expenses		53		94
Total	$	1,010	$	2,113

Debt (Tables)

12 Months Ended

Dec. 31, 2017

Debt

Schedule of minimum aggregate future payments

As of December 31, 2017, minimum aggregate future payments under the Term Loan are as follows (in thousands):


	December 31,

2018	$	2,104
2019		4,281
2020		4,099
2021		1,333
Total minimum payments		11,817
Amount representing interest and discounts		(1,779)
Present value of minimum payments		10,038
Current portion		(1,355)
Long-term portion	$	8,683

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2017

Commitments and Contingencies

Future minimum lease payments


	December 31,

2018	$	104
2019		71
Total	$	175

Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Share-Based Compensation

Schedule of share-based compensation expense

Share-based compensation expense was included in general and administrative and research and development costs as follows in the accompanying statements of comprehensive loss (in thousands):


	Year Ended
	December 31,
	2017		2016		2015
General and administrative	$	4,091	$	1,166	$	284
Research and development		1,182		552		—
Total share-based compensation	$	5,273	$	1,718	$	284

Schedule of RSA grant activity


	Number of		Weighted-Average
	Shares		Fair Value (per share)

Non‑vested at December 31, 2014	994,613	$	0.09
Granted	44,567	$	0.21
Vested	(691,087)	$	0.09
Non‑vested at December 31, 2015	348,093	$	0.09
Granted	—	$	—
Vested	(344,084)	$	0.09
Non‑vested at December 31, 2016	4,009	$	0.21
Granted	—	$	—
Vested	(4,009)	$	0.21
Non‑vested at December 31, 2017	—	$	—

Schedule of stock option plan activity


				Weighted‑
		Weighted		Average
		Average		Remaining	Aggregate
	Number of	Exercise		Contractual	Intrinsic
	Options	Price		Term (years)	Value(1)

Outstanding at December 31, 2014	—	$	—	—	$	—
Granted	305,278	$	2.42	—		—
Exercised	(2,436)	$	1.34	—		—
Forfeited/Cancelled	—	$	—	—		—
Outstanding at December 31, 2015	302,842	$	2.43	9.60	$	1,031,000
Granted	2,023,700	$	10.07	—		—
Exercised	—	$	—	—		—
Forfeited/Cancelled	(83,742)	$	9.12	—		—
Outstanding at December 31, 2016	2,242,800	$	9.07	9.48	$	(2,759,000)
Granted	248,500	$	12.24	—		—
Exercised	(23,910)	$	1.92	—		—
Forfeited/Cancelled	(3,250)	$	1.34	—		—
Outstanding at December 31, 2017	2,464,140	$	9.46	8.58	$	(3,715,000)
Vested and exercisable at December 31, 2017	1,204,533	$	8.53	8.45	$	(699,000)
Vested and expected to vest at December 31, 2017	2,464,140	$	9.46	8.58	$	(3,715,000)

⁽¹⁾

Schedule of weighted-average assumptions, option-pricing model


	Year Ended
	December 31,
	2017			2016			2015

Expected stock price volatility		65.8	%		71.4	%		71.0	%
Expected life of options (years)		5.9			6.0			5.5
Expected dividend yield		0	%		0	%		0	%
Risk free interest rate		2.0	%		1.2	%		1.7	%

Net Loss Per Common Share (Tables)

12 Months Ended

Dec. 31, 2017

Net Loss Per Common Share

Schedule of computation of basic and diluted loss per share

The following table sets forth the computation of basic and diluted loss per share as of December 31, 2017, 2016 and 2015 (in thousands, except share and per share amounts):


	Year Ended
	2017		2016		2015
Numerator:
Net loss	$	(33,415)	$	(14,586)	$	(9,029)
Adjustment to redemption value on Series A convertible preferred stock		—		(366)		(2,968)
Premium upon substantial modification of convertible notes with certain stockholders		—		—		(1,047)
Net loss attributed to common stock holders	$	(33,415)	$	(14,952)	$	(13,044)
Denominator:
Basic and diluted weighted average common shares outstanding		10,349,136		5,809,396		2,875,053
Basic and diluted net loss per share	$	(3.23)	$	(2.57)	$	(4.54)

Schedule of potential common shares not considered in computation of diluted net loss per share


	Year Ended
	2017	2016	2015
Stock options	2,464,140	2,242,800	302,842
Restricted stock awards	—	4,009	348,093
Warrants	978,204	—	—
Series A	—	—	745,637
Convertible notes	—	—	828,751

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2017

Fair Value Measurements

Schedule of premium conversion derivative liabilities measured at fair value on recurring basis using unobservable level 3 inputs


	For the Year Ended December 31,
	2017		2016		2015
Balance as of beginning of period	$	—	$	345	$	73
Issuance of underlying convertible notes		—		505		842
Change in fair value of premium conversion derivative		—		(850)		297
Reversal of premium conversion derivative associated with note extinguishment		—		—		(182)
Redemption of underlying convertible notes		—		—		(685)
Balance as of end of period	$	—	$	—	$	345

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Taxes

Schedule of statutory federal income tax rate to the provision (benefit)


	For the Year Ended December 31,
	2017		2016		2015
Income tax (benefit) provision at federal statutory rate	(34.0)	%	(34.0)	%	(34.0)	%
Valuation allowance	21.0		40.2		38.2
U.S. tax reform	20.2		—		—
State income tax, net of federal benefit	(4.1)		(4.7)		(4.0)
Convertible notes	—		1.1		0.6
Research credits	(3.6)		(4.0)		(1.1)
Other	0.5		1.4		0.3
Effective tax rate	—	%	—	%	—	%

Schedule of deferred tax assets and liabilities

Significant components of the Company’s deferred tax assets and liabilities are summarized in the tables below as of (in thousands):


	Year Ended December 31,
Deferred tax assets:	2017		2016
Federal and state operating loss carryforwards	$	3,349	$	2,289
Research and development costs deferral election		8,881		5,254
Acquired intangibles		235		351
Accruals		—		13
Term loan		33		—
Charitable contributions		14		12
Stock-based compensation		1,722		633
Research and development credit carryforwards		1,947		768
		16,181		9,320
Valuation allowance		(16,181)		(9,320)
Total deferred tax assets, net of valuation allowance		—		—
Deferred tax liabilities:
Total deferred tax liabilities		—		—
Net deferred tax assets	$	—	$	—

Quarterly Data (Tables)

12 Months Ended

Dec. 31, 2017

Supplementary Data — Quarterly Financial Data (unaudited).

Schedule of unaudited consolidated quarterly financial information


	Three Months Ended
	December 31,		September 30,		June 30,		March 31,
	2017		2017		2017		2017
	(in thousands, except per share amounts)
Operating expenses:
General and administrative	$	1,487	$	2,050	$	4,678	$	2,223
Research and development		5,080		6,489		5,837		5,280
Total operating expenses		6,567		8,539		10,515		7,503
Loss from operations		(6,567)		(8,539)		(10,515)		(7,503)
Interest (expense) income		(179)		(132)		13		12
Other expense		—		—		—		(5)
Loss before income taxes		(6,746)		(8,671)		(10,502)		(7,496)
Provision (benefit) for income taxes		—		—		—		—
Net loss		(6,746)		(8,671)		(10,502)		(7,496)
Other comprehensive loss, net of tax		—		—		—		—
Comprehensive loss	$	(6,746)	$	(8,671)	$	(10,502)	$	(7,496)
Net loss per share:
Basic and diluted (A)	$	(0.63)	$	(0.82)	$	(0.99)	$	(0.79)

	Three Months Ended
	December 31,		September 30,		June 30,		March 31,
	2016 (B)		2016 (B)		2016		2016
	(in thousands, except per share amounts)
Operating expenses:
General and administrative	$	2,389	$	1,466	$	1,051	$	1,050
Research and development		4,839		1,936		789		1,176
Total operating expenses		7,228		3,402		1,840		2,226
Loss from operations		(7,228)		(3,402)		(1,840)		(2,226)
Interest income (expense)		13		(475)		449		127
Other income (expense)		1		(1)		—		(4)
Loss before income taxes		(7,214)		(3,878)		(1,391)		(2,103)
Provision (benefit) for income taxes		—		—		—		—
Net loss		(7,214)		(3,878)		(1,391)		(2,103)
Other comprehensive loss, net of tax		—		—		—		—
Comprehensive loss	$	(7,214)	$	(3,878)	$	(1,391)	$	(2,103)
Net loss	$	(7,214)	$	(3,878)	$	(1,391)	$	(2,103)
Adjustment to redemption value on Series A convertible preferred stock		—		(67)		(150)		(149)
Net loss attributable to common stockholders	$	(7,214)	$	(3,945)	$	(1,541)	$	(2,252)
Net loss per share:
Basic and diluted (A)	$	(0.78)	$	(0.56)	$	(0.42)	$	(0.65)

^(A)

Net loss per share for the year may not equal the sum of the four historical quarters loss per share due to changes in weighted-average shares outstanding.

^(B)

The Company and Basis of Presentation (IPO and Capital Requirements) (Details) - USD ($) $ / shares in Units, $ in Thousands				12 Months Ended
	Sep. 08, 2016	Aug. 10, 2016	Aug. 04, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Sale of Stock
Other offering expenses				$ 1,287	$ 3,963	$ 205
IPO
Sale of Stock
Issuance of stock (in shares)			3,000,000
Share price (in dollars per share)			$ 10.00
Net proceeds			$ 26,100
Underwriting discounts and commissions	$ 2,100
Other offering expenses	$ 2,100	$ 4,200
Overallotment
Sale of Stock
Issuance of stock (in shares)	27,755
Share price (in dollars per share)	$ 10.00

The Company and Basis of Presentation (Private Placement Offering) (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Mar. 15, 2017	Mar. 10, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Private Placement Offering
Gross proceeds				$ 30,278	$ 911
Exercise price of warrant			$ 10.40
Class of Warrant or Right, Warrant Term			5 years
Private placement
Private Placement Offering
Issuance of stock (in shares)	1,324,256	1,324,256
Price per issue and sold units	$ 9.47	$ 9.47
Gross proceeds	$ 12,500	$ 12,500	$ 8,979
Number of shares per unit	1	1,000,000
Number of warrants per unit	0.75	0.75
Exercise price of warrant		$ 10.40
Class of Warrant or Right, Warrant Term		5 years

The Company and Basis of Presentation (Reverse Stock Split) (Details)	1 Months Ended
	Apr. 30, 2016
The Company and Basis of Presentation
Reverse stock split	0.320615582

Summary of Significant Accounting Policies (Details)			12 Months Ended
Summary of Significant Accounting Policies (Details)	Aug. 10, 2016 shares	Oct. 31, 2014 USD ($)	Dec. 31, 2017 USD ($) segment shares	Dec. 31, 2016 shares	Mar. 31, 2015 shares
Income Taxes
Provision (benefit) for income taxes \| $			$ 0
Segment Information
Number of operating segment \| segment			1
Series A
Convertible Preferred Stock
Convertible Preferred stock, share issued					745,637
Shares converted	827,205
Convertible Preferred stock, share outstanding			0	0
MLT
Income Taxes
Provision (benefit) for income taxes \| $		$ 0

Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accrued Liabilities
Accrued compensation and other payroll liabilities	$ 306	$ 706
Legal costs	91	54
Accrued interest	38
Other research and development expenses	522	1,259
Other general and administrative expenses	53	94
Total	$ 1,010	$ 2,113

Debt - Term Loan (Details) - USD ($) $ in Thousands				3 Months Ended								12 Months Ended
Debt - Term Loan (Details) - USD ($) $ in Thousands	Jul. 31, 2018	Mar. 31, 2018	Jul. 24, 2017	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt
Interest (expense) income				$ (179)	$ (132)	$ 13	$ 12	$ 13	$ (475)	$ 449	$ 127	$ (286)	$ 114	$ (762)
Minimum aggregate future payments
Current portion				(1,355)								(1,355)
Long-term portion				8,683								8,683
Term Loan
Debt
Principal amount			$ 15,000
Convertible interest rate (as a percentage)			5.00%
Debt issue costs				100								100
Final payment fee (as a percentage)			10.00%
Success fee (as a percentage)			3.50%
Interest (expense) income												300
Minimum aggregate future payments
2018				2,104								2,104
2019				4,281								4,281
2020				4,099								4,099
2021				1,333								1,333
Total minimum payments				11,817								11,817
Amount representing interest and discounts				(1,779)								(1,779)
Present value of minimum payments				10,038								10,038
Current portion				(1,355)								(1,355)
Long-term portion				$ 8,683								$ 8,683
Term Loan \| Minimum
Debt
Interest rate Percentage				4.25%								4.25%
Term Loan \| Minimum \| Subsequent Event
Debt
Cash security (as a percentage)	50.00%	100.00%
Term Loan \| Maximum
Debt
Interest rate Percentage				4.50%								4.50%
Term Loan \| Prior to first anniversary effective date
Debt
Prepayment fee (as a percentage)			2.00%
Term Loan \| Occurs thereafter
Debt
Prepayment fee (as a percentage)			1.00%
Initial Tranche
Debt
Principal amount			$ 10,000
Additional Tranche available to be drawn through July 31, 2018
Debt
Principal amount			$ 5,000

Debt - Intermin Notes (Details) - Interim Notes			1 Months Ended			3 Months Ended	12 Months Ended
Debt - Intermin Notes (Details) - Interim Notes	Aug. 10, 2016 shares	Jul. 31, 2015 USD ($)	Apr. 30, 2016 USD ($)	Feb. 29, 2016 USD ($)	Dec. 31, 2015 USD ($) $ / shares	Sep. 30, 2015 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) $ / shares
Debt
Proceeds from issuance of convertible notes		$ 2,800,000	$ 5,000,000	$ 200,000	$ 2,700,000	$ 2,800,000
Shares converted \| shares	1,656,807
Convertible interest rate (as a percentage)		8.00%
Qualified Financing threshold for debt conversion		$ 5,000,000
Debt redemption price		200.00%
Principal amount			10,600,000	$ 5,600,000	$ 5,500,000		$ 0	$ 0	$ 5,500,000
Debt issue costs			$ 10,000
Conversion ratio		1.15	1.25
Conversion price \| $ / shares					$ 6.70585				$ 6.70585
Conversion of convertible notes to common stock, shares \| shares	1,656,807
Premium conversion derivative							0
Interest income (expense)
Debt
Change in fair value of embedded derivative							$ 0	$ 200,000	$ (100,000)

Debt - Convertible Notes (Details) - Convertible Notes - USD ($)		3 Months Ended	4 Months Ended	12 Months Ended
	Mar. 31, 2015	Mar. 31, 2016	Feb. 18, 2015	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016	Nov. 01, 2014
Debt
Proceeds from issuance of convertible notes		$ 2,000,000	$ 2,700,000
Convertible interest rate (as a percentage)							8.00%
Conversion price percentage of principal and unpaid accrued interest	125.00%
Principal amount					$ 0	$ 0
Interest income (expense)
Debt
Change in fair value of embedded derivative				$ (400,000)

Commitments and Contingencies - Pfizer License Agreement (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Commitments and Contingencies
No liabilities were recorded related to the license agreement	$ 15,076,000	$ 4,122,000
Pfizer, Inc. \| License Agreement
Commitments and Contingencies
No liabilities were recorded related to the license agreement	$ 0

Commitments and Contingencies - Preferred Stock Dividends (Details) - Series A Convertible Preferred Stock. - USD ($)		12 Months Ended
	Aug. 10, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Convertible Series A Preferred Stock
Dividend rate		8.00%
Original issue price, per share					$ 6.70585
Shares converted	827,205
Cumulative unpaid dividends		$ 0	$ 0	$ 300,000

Commitments and Contingencies - Other Agreements (Details) - USD ($)	1 Months Ended	12 Months Ended
	May 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transactions
Agreement Term	3 years
Monthly base rent	$ 8,400
Lease term monthly base rate	$ 8,900
Future minimum lease payments of operating leases:
2018		$ 104,000
2019		71,000
Total		175,000
Office Rental
Related Party Transactions
Rent expense		$ 100,000	$ 58,000	$ 23,000

License Agreement (Details) - USD ($) $ in Thousands		12 Months Ended
License Agreement (Details) - USD ($) $ in Thousands	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2017
License Agreements
Issuance of common stock		$ 30,278	$ 911
Common Stock
License Agreements
Issuance of stock (in shares)		3,027,755	677,685
Issuance of common stock		$ 3	$ 3
Pfizer, Inc. \| License Agreement
License Agreements
Percentage of shares of common stock offering issued to Pfizer	15.00%
Pfizer, Inc. \| License Agreement \| Common Stock
License Agreements
Issuance of stock (in shares)	675,250
Issuance of common stock	$ 900
Pfizer, Inc. \| License Agreement \| Common Stock \| Minimum
License Agreements
Ownership by Pfizer	5.00%
Pfizer, Inc. \| License Agreement \| Milestone Payments \| Maximum
License Agreements
Potential payments upon achievement of certain milestones	$ 37,000			$ 0

Convertible Series A Preferred Stock (Details) - USD ($)			12 Months Ended
	Aug. 10, 2016	Mar. 31, 2015	Dec. 31, 2017	Dec. 31, 2015	Dec. 31, 2016
Convertible Series A Preferred Stock
Cash proceeds from issuance of Series A preferred				$ 1,522,000
Dividends deemed payable and accrued			$ 0		$ 0
Convertible Notes
Convertible Series A Preferred Stock
Conversion price percentage of principal and unpaid accrued interest		125.00%
Series A Convertible Preferred Stock.
Convertible Series A Preferred Stock
Issuance of convertible Series A preferred stock (shares)		745,637		745,637
Original issue price, per share		$ 6.70585
Aggregate consideration, cash and noncash		$ 5,000,000
Shares converted	827,205
Dividend rate			8.00%
Liquidation preference, per share			$ 6.70585
Series A Convertible Preferred Stock. \| Minimum
Convertible Series A Preferred Stock
Liquidation preference upon transfer of voting power, percentage			50.00%
Percentage of outstanding shares which may require the Company to redeem shares			80.00%
Redemption price, as a percent of liquidation preference			150.00%
Series A Convertible Preferred Stock. \| Convertible Notes
Convertible Series A Preferred Stock
Noncash consideration received, debt converted into stock		$ 3,500,000
Conversion price percentage of principal and unpaid accrued interest		125.00%

Stockholders’ and Members' Deficit (Details) - USD ($) $ / shares in Units, $ in Thousands			12 Months Ended
	Mar. 15, 2017	Mar. 10, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Common Stock
Common Stock, share issued			10,633,042	9,270,255
Gross proceeds				$ 30,278	$ 911
Issuance costs of offering				$ 4,168
Private placement
Common Stock
Issuance of stock (in shares)	1,324,256	1,324,256
Price per issue and sold units	$ 9.47	$ 9.47
Gross proceeds	$ 12,500	$ 12,500	$ 8,979
Number of shares per unit	1	1,000,000
Number of warrants per unit	0.75	0.75
Issuance costs of offering	$ 1,300		$ 1,287

Stockholders’ and Members' Deficit - Warrants (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Warrants
Purchase of additional common stock through warrants	993,204
Term of warrants	5 years
Exercise price of warrant \| $ / shares	$ 10.40
Fair market value of warrant \| $	$ 4.9
Risk-free interest rate	2.00%
Contractual term	5 years
Dividend yield	0.00%
Volatility factor	65.10%
Exercise of warrants (in shares)	15,000
Class of Warrant or Right, Outstanding	978,204

Stockholders’ and Members' Deficit - Dividend Rights (Details)			12 Months Ended
	Sep. 08, 2016 USD ($)	Aug. 10, 2016 USD ($)	Dec. 31, 2017 USD ($) Vote / shares	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Offering Costs
Offering costs			$ 1,287,000	$ 3,963,000	$ 205,000
Deferred offering costs			21,000
Common Stock
Dividends Rights
No dividends declared			$ 0
Voting Rights
Common stock, vote per share \| Vote / shares			1
IPO
Offering Costs
Offering costs	$ 2,100,000	$ 4,200,000
Deferred offering costs			$ 0

Share-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
Share-Based Compensation (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation	$ 5,273	$ 1,718	$ 284
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation	4,091	1,166	$ 284
Research and development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation	$ 1,182	$ 552

Share-Based Compensation (Restricted Stock 10K) (Details) - Restricted stock awards - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restricted Stock Awards
Forfeited (in shares)		0	0	0
Fair value (in dollars)			$ 9,000
RSA grant activity [Rollforward], Number of Shares
Non‑vested , Beginning Balance (in shares)	4,009	348,093	994,613
Granted (in shares)			44,567
Vested (in shares)	(4,009)	(344,084)	(691,087)
Non‑vested , Ending Balance (in shares)		4,009	348,093	994,613
RSA grant activity [Rollforward], Weighted-Average Fair Value (per share)
Non‑vested , Beginning Balance (per share)	$ 0.21	$ 0.09	$ 0.09
Granted (per share)			0.21
Vested (per share)	$ 0.21	0.09	0.09
Non‑vested , Ending Balance (per share)		$ 0.21	$ 0.09	$ 0.09
Minimum
Restricted Stock Awards
Vesting period	6 months
Maximum
Restricted Stock Awards
Vesting period	24 months

Share-Based Compensation (Stock Options 10K) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2016	Apr. 30, 2016	Apr. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected stock price volatility	65.80%	71.40%	71.00%
Expected life of options (years)	5 years 10 months 24 days	6 years	5 years 6 months
Expected dividend yield	0.00%	0.00%	0.00%
Risk free interest rate	2.00%	1.20%	1.70%
2015 Plan
Stock Options, Additional Disclosures
Vested	861,645	276,248	104,907
2015 Plan \| Employees, directors and consultants
Stock Options, Additional Disclosures
Forfeited			0
Common stock reserved for issuance (in shares)						320,615
A&R 2015 Plan
Stock Options, Additional Disclosures
Common stock reserved for issuance (in shares)	0
A&R 2015 Plan \| Officers, directors and employees
Number of Options
Granted (in shares)	150,500	1,825,700	305,278
A&R 2015 Plan \| Officers, directors and employees \| Minimum
Stock Options, Additional Disclosures
Vesting period	3 years
A&R 2015 Plan \| Officers, directors and employees \| Maximum
Stock Options, Additional Disclosures
Vesting period	4 years
A&R 2015 Plan \| Employees, directors and consultants
Stock Options, Additional Disclosures
Available for future issuance	212,329
Common stock reserved for issuance (in shares)					2,400,000
Inducement Plan
Stock Options, Additional Disclosures
Common stock reserved for issuance (in shares)				300,000
Inducement Plan \| Officers and Employees
Stock Options, Additional Disclosures
Vesting period	4 years
Number of Options
Granted (in shares)	98,000	198,000
Inducement Plan \| Employees, directors and consultants
Stock Options, Additional Disclosures
Available for future issuance	0
Stock options
Stock Options, Additional Disclosures
Options, Outstanding, Weighted Average Remaining Contractual Term (years)	8 years 6 months 29 days	9 years 5 months 23 days	9 years 7 months 6 days
Vested and exercisable (years)	8 years 5 months 12 days
Vested and expected to vest (years)	8 years 6 months 29 days
Options, Outstanding, Aggregate Intrinsic Value	$ (3,715,000)	$ (2,759,000)	$ 1,031,000
Vested and exercisable	(699,000)
Vested and expected to vest	$ (3,715,000)
Common stock aggregate intrinsic value of exercise price	$ 7.95	$ 7.84	$ 5.83
Weighted average fair value per share of options granted	7.35	6.37	1.50
Weighted average fair value per share of options vested	$ 9.45	$ 4.59	$ 1.05
Forfeited	3,250	83,742
Number of Options
Outstanding, Number, Beginning Balance (in shares)	2,242,800	302,842
Granted (in shares)	248,500	2,023,700	305,278
Exercised (in shares)	(23,910)		(2,436)
Forfeited/Cancelled (in shares)	(3,250)	(83,742)
Outstanding, Number, Ending Balance (in shares)	2,464,140	2,242,800	302,842
Vested and exercisable (in shares)	1,204,533
Vested and expected to vest (in shares)	2,464,140
Weighted Average Exercise Price
Outstanding, Weighted Average Exercise Price, Beginning Balance (in dollars per share)	$ 9.07	$ 2.43
Granted (in dollars per share)	12.24	10.07	$ 2.42
Exercised (in dollars per share)	1.92		1.34
Forfeited/Cancelled (in dollars per share)	1.34	9.12
Outstanding, Weighted Average Exercise Price, Ending Balance (in dollars per share)	9.46	$ 9.07	$ 2.43
Vested and exercisable (in dollars per share)	8.53
Vested and expected to vest (in dollars per share)	$ 9.46
Restricted stock awards \| Minimum
Stock Options, Additional Disclosures
Vesting period	6 months
Restricted stock awards \| Maximum
Stock Options, Additional Disclosures
Vesting period	24 months

Share-Based Compensation (Unrecognized) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2018	Apr. 30, 2016
Unrecognized share-based compensation
Unrecognized share-based compensation cost	$ 6.9
Unrecognized share-based compensation - Weighted average period	2 years 3 months 18 days
Stock options
Share-based compensation
Granted (in shares)	248,500	2,023,700	305,278
ESPP
Share-based compensation
Common stock reserved for issuance (in shares)					150,000
Granted (in shares)	0
A&R 2015 Plan
Share-based compensation
Number of years common shares automatically increase	10 years
Percentage of company's fully diluted shares	20.00%
Common stock reserved for issuance (in shares)	0
Forecast \| A&R 2015 Plan
Share-based compensation
Common stock reserved for issuance (in shares)				415,077

Net Loss Per Common Share (Details) - USD ($)	12 Months Ended
Net Loss Per Common Share (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Loss Per Common Share
Loss allocated to preferred stock	$ 0
Incremental common stock equivalents		0	0	0

Net Loss Per Common Share - Earning Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Numerator:
Net loss	$ (6,746)	$ (8,671)	$ (10,502)	$ (7,496)	$ (7,214)	$ (3,878)	$ (1,391)	$ (2,103)	$ (33,415)	$ (14,586)	$ (9,029)
Adjustment to redemption value on Series A convertible preferred stock						(67)	(150)	(149)		(366)	(2,968)
Premium upon substantial modification of convertible notes with certain stockholders											(1,047)
Net loss attributable to common stockholders					$ (7,214)	$ (3,945)	$ (1,541)	$ (2,252)	$ (33,415)	$ (14,952)	$ (13,044)
Denominator:
Basic and diluted weighted average common shares outstanding									10,349,136	5,809,396	2,875,053
Basic and diluted	$ (0.63)	$ (0.82)	$ (0.99)	$ (0.79)	$ 0.78	$ 0.56	$ 0.42	$ 0.65	$ (3.23)	$ (2.57)	$ (4.54)

Net Loss Per Common Share - Antidilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock options
Potential common shares
Potential common shares		4,009	348,093
Restricted stock awards
Potential common shares
Potential common shares	2,464,140	2,242,800	302,842
Warrants
Potential common shares
Potential common shares	978,204
Series A
Potential common shares
Potential common shares			745,637
Convertible notes
Potential common shares
Potential common shares			828,751

Fair Value Measurements - Narrative (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Recurring
Fair value measurements
Total liabilities at Fair Value	$ 0	$ 0
Nonrecurring
Fair value measurements
Total liabilities at Fair Value	$ 0	$ 0	$ 0

Fair Value Measurements - Roll-Forward of Premium conversion Derivative Liabilities (Details) - Premium conversion derivative - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Roll-forward of the company's premium conversion derivative liabilities
Balance as of beginning of period	$ 345	$ 73
Issuance of underlying convertible notes	505	842
Change in fair value of premium conversion derivative	(850)	297
Reversal of premium conversion derivative associated with note extinguishment		(182)
Redemption of underlying convertible notes		(685)
Balance as of end of period	$ 345	$ 345

Income Taxes (Details) - USD ($) $ in Millions			12 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Jan. 01, 2019	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes
US Corporate income tax rate	21.00%	35.00%	34.00%	34.00%	34.00%
Change in tax rate rate income tax expense (benefit)			$ 6.8
Effective tax rate			0.00%	0.00%	0.00%

Income Taxes - Reconciliation of income tax (Details)			12 Months Ended
Income Taxes - Reconciliation of income tax (Details)	Jan. 01, 2019	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of income tax:
Income tax (benefit) provision at federal statutory rate (as a percent)	(21.00%)	(35.00%)	(34.00%)	(34.00%)	(34.00%)
Valuation allowance			21.00%	40.20%	38.20%
U.S. tax reform (as a percent)			20.20%
State income tax, net of federal benefit (as a percent)			(4.10%)	(4.70%)	(4.00%)
Convertible notes (as a percent)				1.10%	0.60%
Research credits (as a percent)			(3.60%)	(4.00%)	(1.10%)
Other (as a percent)			0.50%	1.40%	0.30%
Effective tax rate (as a percent)			0.00%	0.00%	0.00%

Income Taxes -Significant components of deferred tax assets and liabilitie (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Federal and state operating loss carryforwards	$ 3,349	$ 2,289
Research and development costs deferral election	8,881	5,254
Acquired intangibles	235	351
Accruals		13
Term loan	33
Charitable contributions	14	12
Stock-based compensation	1,722	633
Research and development credit carryforwards	1,947	768
Total deferred tax assets	16,181	9,320
Valuation allowance	$ (16,181)	$ (9,320)

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Operating loss carryforwards
Deferred Tax Assets, Valuation Allowance, Total	$ 16,181,000	$ 9,320,000
Federal net operating loss carryforwards	2,800,000	2,100,000
Research and development credit carryforwards	1,947,000	768,000
State net operating loss carryforwards	600,000	200,000
State research credit carryforwards	$ 45,000	24,000
Income tax:
Threshold percentage of shareholders ownership change	5.00%
Minimum increase in ownership percentage annual limitation may result in expiration of NOL and credits	50.00%
Period for testing percentage of ownership change	36 months
Uncertain tax positions	$ 0	0
Interest or penalties	$ 0	$ 0

Quarterly Data (Details) - USD ($)	3 Months Ended								12 Months Ended
Quarterly Data (Details) - USD ($)	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating expenses:
General and administrative	$ 1,487,000	$ 2,050,000	$ 4,678,000	$ 2,223,000	$ 2,389,000	$ 1,466,000	$ 1,051,000	$ 1,050,000	$ 10,438,000	$ 5,956,000	$ 3,177,000
Research and development	5,080,000	6,489,000	5,837,000	5,280,000	4,839,000	1,936,000	789,000	1,176,000	22,686,000	8,740,000	3,991,000
Total operating expenses	6,567,000	8,539,000	10,515,000	7,503,000	7,228,000	3,402,000	1,840,000	2,226,000	33,124,000	14,696,000	8,076,000
Loss from operations	(6,567,000)	(8,539,000)	(10,515,000)	(7,503,000)	(7,228,000)	(3,402,000)	(1,840,000)	(2,226,000)	(33,124,000)	(14,696,000)	(8,076,000)
Interest (expense) income	(179,000)	(132,000)	13,000	12,000	13,000	(475,000)	449,000	127,000	(286,000)	114,000	(762,000)
Other income				(5,000)	1,000	(1,000)		(4,000)	(5,000)	(4,000)	7,000
Loss before income taxes	(6,746,000)	(8,671,000)	(10,502,000)	(7,496,000)	(7,214,000)	(3,878,000)	(1,391,000)	(2,103,000)	(33,415,000)	(14,586,000)	(9,029,000)
Provision (benefit) for income taxes									0
Net loss	(6,746,000)	(8,671,000)	(10,502,000)	(7,496,000)	(7,214,000)	(3,878,000)	(1,391,000)	(2,103,000)	(33,415,000)	(14,586,000)	(9,029,000)
Comprehensive loss	(6,746,000)	(8,671,000)	(10,502,000)	(7,496,000)	(7,214,000)	(3,878,000)	(1,391,000)	(2,103,000)	(33,415,000)	(14,586,000)	(9,029,000)
Net loss	$ (6,746,000)	$ (8,671,000)	$ (10,502,000)	$ (7,496,000)	(7,214,000)	(3,878,000)	(1,391,000)	(2,103,000)	(33,415,000)	(14,586,000)	(9,029,000)
Adjustment to redemption value on Series A convertible preferred stock						(67,000)	(150,000)	(149,000)		(366,000)	(2,968,000)
Net loss attributable to common stockholders					$ (7,214,000)	$ (3,945,000)	$ (1,541,000)	$ (2,252,000)	$ (33,415,000)	$ (14,952,000)	$ (13,044,000)
Net loss per share:
Basic and diluted	$ (0.63)	$ (0.82)	$ (0.99)	$ (0.79)	$ 0.78	$ 0.56	$ 0.42	$ 0.65	$ (3.23)	$ (2.57)	$ (4.54)

Related Party Transactions - Rental agreement (Details) - Office Rental	12 Months Ended
	Dec. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($) item
Related Party Transactions
Rent expense	$ 100,000	$ 58,000	$ 23,000
LLC owned by two officers
Related Party Transactions
Number of officers \| item	2	2	2
Rent expense		$ 21,000	$ 23,000

Related Party Transactions - Convertible Notes (Details) $ in Millions		3 Months Ended		4 Months Ended
	Mar. 31, 2015 item shares	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($) item	Feb. 18, 2015 USD ($)
Convertible Notes
Related Party Transactions
Proceeds from issuance of convertible notes \| $		$ 2.0		$ 2.7
Convertible Notes \| Series A Convertible Preferred Stock.
Related Party Transactions
Proceeds from issuance of convertible notes \| $			$ 2.0
Amount of shares issued in conversion \| shares	516,421
Two Officers \| Convertible Notes \| Series A Convertible Preferred Stock.
Related Party Transactions
Amount of shares issued in conversion \| shares	68,649
Two Officers \| Debt Issued To Related Parties \| Convertible Notes \| Series A Convertible Preferred Stock.
Related Party Transactions
Number of officers	2
Investors Related To Board Member And Officers \| Convertible Notes \| Series A Convertible Preferred Stock.
Related Party Transactions
Amount of shares issued in conversion \| shares	63,967
Investors Related To Board Member And Officers \| Debt Issued To Related Parties \| Series A Convertible Preferred Stock.
Related Party Transactions
Number of notes issued to related party	4		4
Number of officers			3
Investors Related To Board Member And Officers \| Debt Issued To Related Parties \| Convertible Notes \| Series A Convertible Preferred Stock.
Related Party Transactions
Proceeds from issuance of convertible notes \| $			$ 0.3
Number of board members related to investors	1		1
Number of officers	3

Related Party Transactions - Interim Notes (Details) - Interim Notes		1 Months Ended			3 Months Ended
	Jul. 31, 2015 USD ($)	Apr. 30, 2016 USD ($) item	Feb. 29, 2016 USD ($) item	Dec. 31, 2015 USD ($) item	Sep. 30, 2015 USD ($) item
Related Party Transaction [Line Items]
Proceeds from issuance of convertible notes \| $	$ 2,800,000	$ 5,000,000	$ 200,000	$ 2,700,000	$ 2,800,000
Debt Issued To Related Parties
Related Party Transaction [Line Items]
Proceeds from issuance of convertible notes \| $		5,000,000
Investors - 2 officers and 3 Board members \| Debt Issued To Related Parties
Related Party Transaction [Line Items]
Proceeds from issuance of convertible notes \| $					$ 500,000
Number of notes issued to related party					5
Number of board members related to investors					3
Number of officers					2
Investors - 3 officers and 1 employee \| Debt Issued To Related Parties
Related Party Transaction [Line Items]
Proceeds from issuance of convertible notes \| $					$ 300,000
Number of notes issued to related party					4
Number of officers					3
Number of employees					1
Investors - 2 officers and 4 Board members \| Debt Issued To Related Parties
Related Party Transaction [Line Items]
Proceeds from issuance of convertible notes \| $				$ 600,000
Number of notes issued to related party				6
Number of board members related to investors				4
Number of officers				2
Investors related to 3 officers \| Debt Issued To Related Parties
Related Party Transaction [Line Items]
Proceeds from issuance of convertible notes \| $				$ 200,000
Number of notes issued to related party				5
Number of officers				3
Investor - 2 Board members \| Debt Issued To Related Parties
Related Party Transaction [Line Items]
Proceeds from issuance of convertible notes \| $			$ 81,000
Number of notes issued to related party			2
Number of board members related to investors			2
Investor related to an officer \| Debt Issued To Related Parties
Related Party Transaction [Line Items]
Proceeds from issuance of convertible notes \| $			$ 20,000
Investors related to 2 officers \| Debt Issued To Related Parties
Related Party Transaction [Line Items]
Proceeds from issuance of convertible notes \| $		$ 200,000
Number of notes issued to related party		2
Number of officers		2
Investors related to three directors \| Debt Issued To Related Parties
Related Party Transaction [Line Items]
Proceeds from issuance of convertible notes \| $		$ 2,300,000
Number of notes issued to related party		3
Number of board members related to investors		3

Related Party Transactions - IPO and Private Placement (Details) $ in Thousands				12 Months Ended
	Mar. 15, 2017 USD ($) person director shares	Mar. 10, 2017 USD ($) shares	Aug. 04, 2016 USD ($) person director shares	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Related Party Transaction [Line Items]
Gross proceeds \| $					$ 30,278	$ 911
IPO
Related Party Transaction [Line Items]
Number of shares sold to 5 officers and 3 board members \| shares			154,450
Number of officers \| person			5
Number of board members \| director			3
Proceeds from issuance of shares to 5 officers and 3 board members \| $			$ 1,500
Number of shares sold to 1 investor related to 1 of the Company's directors \| shares			500,000
Number of investor related to 1 of the Company’s directors \| person			1
Number of shares sold to 14 investors who are related to 5 officers of the Company \| shares			47,000
Proceeds from issuance of shares to 14 investors who are related to 5 officers of the Company \| $			$ 500
Number of investors related to 5 officers of the company \| person			14
Issuance of stock (in shares) \| shares			3,000,000
Proceeds from issuance of shares to 1 investor related to 1 of the Company's directors \| $			$ 5,000
Private placement
Related Party Transaction [Line Items]
Issuance of stock (in shares) \| shares	1,324,256	1,324,256
Gross proceeds \| $	$ 12,500	$ 12,500		$ 8,979
Three Board Members \| Private placement
Related Party Transaction [Line Items]
Number of board members \| director	3
Issuance of stock (in shares) \| shares	56,678
Gross proceeds \| $	$ 500
One Board Member \| Private placement
Related Party Transaction [Line Items]
Number of board members \| director	1
Issuance of stock (in shares) \| shares	52,798
Gross proceeds \| $	$ 500
Number of investor \| person	1

Defined Contribution Plan (Details)	12 Months Ended
Defined Contribution Plan (Details)	Dec. 31, 2017 USD ($) age
Defined Contribution Plan Disclosure [Line Items]
Minimum age of employee to cover under the plan \| age	21
Employee compensation deferred percentage	100.00%
Employer match of employee contributions of eligible compensation	100.00%
Percentage of compensation matched by employer	3.00%
Employer match of over all employee contributions of eligible compensation	50.00%
Percentage of employee contribution vested on their contribution	100.00%
Employer matches vesting period	6 years
Amount of discretionary matching contributions on employee deferrals \| $	$ 0
Maximum
Defined Contribution Plan Disclosure [Line Items]
Percentage of compensation matched by employer	5.00%

Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
	Sep. 08, 2016	Mar. 31, 2018
Overallotment
Subsequent Events
Issuance of stock (in shares)	27,755
Share price (in dollars per share)	$ 10.00
Subsequent Event
Subsequent Events
Issuance of stock (in shares)		3,592,858
Share price (in dollars per share)		$ 7.00
Subsequent Event \| Overallotment
Subsequent Events
Issuance of stock (in shares)		450,000
Net proceeds		$ 23.0
1 Officer \| Subsequent Event
Subsequent Events
Issuance of stock (in shares)		14,286
Net proceeds		$ 0.1
Investors Related To Board Member And Officers \| Subsequent Event
Subsequent Events
Issuance of stock (in shares)		71,429
Net proceeds		$ 0.5

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
VALUATION AND QUALIFYING ACCOUNTS
Beginning Balance of Period	$ 9,320	$ 3,657	$ 72
Additions Charged to Costs and Expenses	6,861	5,937	3,447
Additions Charged to Paid in Capital		(274)	138
Ending Balance of Period	$ 16,181	$ 9,320	$ 3,657

Label	Element	Value
Redeemable Convertible Preferred Stock [Member]
Temporary Equity, Stock Issued During Period, Value, New Issues	us-gaap_TemporaryEquityStockIssuedDuringPeriodValueNewIssues	$ 4,985,000
Redemption value adjustment - Series A preferred stock	us-gaap_TemporaryEquityAccretionToRedemptionValue	$ 2,968,000