Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2016	Aug. 10, 2016
Document and Entity Information
Entity Registrant Name	Aclaris Therapeutics, Inc.
Entity Central Index Key	0001557746
Document Type	10-Q
Document Period End Date	Jun. 30, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		21,415,397
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q2

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 31,815	$ 9,851
Marketable securities	62,195	75,017
Prepaid expenses and other current assets	1,628	1,656
Total current assets	95,638	86,524
Marketable securities		7,170
Property and equipment, net	434	360
Other assets	20	22
Total assets	96,092	94,076
Current liabilities:
Accounts payable	3,309	810
Accrued expenses	2,198	745
Total current liabilities	5,507	1,555
Other liabilities	345
Total liabilities	5,852	1,555
Stockholders' Equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized and no shares issued or outstanding at June 30, 2016 and December 31, 2015
Common stock, $0.00001 par value; 100,000,000 shares authorized at June 30, 2016 and December 31, 2015; 21,403,005 and 20,157,503 shares issued and outstanding at June 30, 2016 and December 31, 2015, respectively
Additional paid-in capital	158,982	135,503
Accumulated other comprehensive income (loss)	1	(149)
Accumulated deficit	(68,743)	(42,833)
Total stockholders’ equity	90,240	92,521
Total liabilities and stockholders’ equity	$ 96,092	$ 94,076

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2016	Dec. 31, 2015
Condensed Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.00001	$ 0.00001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	21,403,005	20,157,503
Common stock, shares outstanding	21,403,005	20,157,503

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Operating expenses:
Research and development	$ 9,836	$ 1,793	$ 19,371	$ 3,530
General and administrative	3,153	803	6,757	1,695
Total operating expenses	12,989	2,596	26,128	5,225
Loss from operations	(12,989)	(2,596)	(26,128)	(5,225)
Other income, net	118	2	218	8
Net loss	(12,871)	(2,594)	(25,910)	(5,217)
Accretion of convertible preferred stock		(676)		(1,333)
Net loss attributable to common stockholders	$ (12,871)	$ (3,270)	$ (25,910)	$ (6,550)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.62)	$ (1.52)	$ (1.27)	$ (3.04)
Weighted average common shares outstanding, basic and diluted (in shares)	20,663,088	2,154,953	20,417,301	2,154,953
Other comprehensive (loss) income:
Unrealized gain on marketable securities, net of tax of $0	$ 14	$ 3	$ 156	$ 6
Foreign currency translation adjustments	(16)		(6)
Total other comprehensive (loss) income	(2)	3	150	6
Comprehensive loss	$ (12,873)	$ (2,591)	$ (25,760)	$ (5,211)

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Parenthetical) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Condensed Consolidated Statements Of Operations And Comprehensive Loss
Unrealized gain on marketable securities, tax	$ 0	$ 0

CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - 6 months ended Jun. 30, 2016 - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance at Dec. 31, 2015		$ 135,503	$ (149)	$ (42,833)	$ 92,521
Balance (in shares) at Dec. 31, 2015	20,157,503				20,157,503
Increase (Decrease) in Stockholders' Equity
Issuance of common stock in connection with Vixen acquisition		2,355			$ 2,355
Issuance of common stock in connection with Vixen acquisition, shares	159,420
Issuance of common stock in connection with private placement, net of offering costs		18,547			18,547
Issuance of common stock in connection with private placement, shares	1,081,082
Exercise of stock options		1			$ 1
Exercise of stock options, shares	5,000				5,000
Unrealized gain on marketable securities			156		$ 156
Foreign currency translation adjustment			(6)		(6)
Stock-based compensation expense		2,576			2,576
Net loss				(25,910)	(25,910)
Balance at Jun. 30, 2016		$ 158,982	$ 1	$ (68,743)	$ 90,240
Balance (in shares) at Jun. 30, 2016	21,403,005				21,403,005

CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (Parenthetical) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($)
Condensed Consolidated Statement Of Stockholders' Equity
Offering costs offset against additional paid in capital	$ 1,453

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net loss	$ (25,910)	$ (5,217)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	48	25
Stock-based compensation expense	2,576	85
Non-cash charges related to Vixen acquisition	2,784
Changes in operating assets and liabilities:
Prepaid expenses and other assets	30	(387)
Accounts payable	2,493	(448)
Accrued expenses	1,353	278
Net cash used in operating activities	(16,626)	(5,664)
Cash flows from investing activities:
Purchases of property and equipment	(106)	(242)
Purchases of marketable securities	(11,282)
Proceeds from sales and maturities of marketable securities	31,430	5,897
Net cash provided by investing activities	20,042	5,655
Cash flows from financing activities:
Proceeds from issuance of common stock in connection with private placement, net of issuance costs	18,547
Proceeds from the exercise of employee stock options	1
Payment of deferred offering costs		(895)
Net cash used in financing activities	18,548	(895)
Net increase (decrease) in cash and cash equivalents	21,964	(904)
Cash and cash equivalents at beginning of period	9,851	10,757
Cash and cash equivalents at end of period	31,815	9,853
Supplemental disclosures of non-cash investing and financing activities:
Additions to property and equipment included in accounts payable	18
Accretion of convertible preferred stock to redemption value		1,333
Fair value of stock issued in connection with Vixen acquisition on date of issuance	$ 2,355
Deferred offering costs included in accounts payable		$ 233

Organization and Nature of Business	6 Months Ended
Organization and Nature of Business	Jun. 30, 2016
Organization and Nature of Business
Organization and Nature of Business	1. Organization and Nature of Business Aclaris Therapeutics, Inc. was incorporated under the laws of the State of Delaware in 2012. On July 17, 2015, Aclaris Therapeutics International Limited (“ATIL”) was established under the laws of the United Kingdom as a wholly-owned subsidiary of Aclaris Therapeutics, Inc. On March 24, 2016, Vixen Pharmaceuticals, Inc. (“Vixen”) became a wholly-owned subsidiary of Aclaris Therapeutics, Inc. (see Note 11). Aclaris Therapeutics, Inc., together with ATIL and Vixen, are referred to collectively as the “Company”. The Company is a clinical‑stage specialty pharmaceutical company focused on identifying, developing and commercializing innovative and differentiated drugs to address significant unmet needs in dermatology. The Company’s lead drug candidate, A‑101, is a proprietary high‑concentration hydrogen peroxide topical solution that is being developed as a prescription treatment for seborrheic keratosis (“SK”), a common non‑malignant skin tumor. The Company has completed three Phase 2 clinical trials and is currently conducting three Phase 3 clinical trials of A-101 in patients with SK. Initial Public Offering On October 6, 2015, the Company’s registration statement on Form S-1 relating to its initial public offering of its common stock (the “IPO”) was declared effective by the Securities and Exchange Commission (“SEC”). The Company’s common stock began trading on The NASDAQ Global Select Market on October 7, 2015. The IPO closed on October 13, 2015, and 5,000,000 shares of common stock were sold at a price to the public of $11.00 per share, for aggregate gross proceeds of $55,000. In addition, upon the closing of the IPO, all of the Company’s outstanding convertible preferred stock was converted into an aggregate total of 11,677,076 shares of common stock. On October 12, 2015, the underwriters of the IPO exercised in full their option to purchase additional shares, and on October 13, 2015, the Company sold 750,000 additional shares of common stock at a price to the public of $11.00 per share, for aggregate gross proceeds of $8,250. The Company paid underwriting discounts and commissions of $4,428 to the underwriters in connection with the IPO, including the underwriters’ exercise of their option to purchase additional shares. In addition, the Company incurred expenses of $2,272 in connection with the IPO. The net offering proceeds received by the Company, after deducting underwriting discounts, commissions and offering expenses, were $56,550. Private Placement On June 2, 2016, pursuant to a securities purchase agreement with certain accredited investors dated May 27, 2016, the Company closed a private placement in which it sold an aggregate of 1,081,082 shares of common stock at a price of $18.50 per share, for gross proceeds of $20,000. The Company incurred placement agent fees of $1,300 and expenses of $153 in connection with the private placement. The net offering proceeds received by the Company, after deducting placement agent fees and transaction expenses, were $18,547. Reverse Stock Split On September 24, 2015, the Company effected a 1‑for‑3.45 reverse stock split of its issued and outstanding shares of common stock and a proportional adjustment to the existing conversion ratios for each series of the Company’s then-outstanding convertible preferred stock. Accordingly, all share and per share amounts for all periods presented in these condensed consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse stock split and adjustment of the preferred stock conversion ratios. Liquidity The Company’s condensed consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities in the ordinary course of business. At June 30, 2016, the Company had cash, cash equivalents and marketable securities of $94,010 and an accumulated deficit of $68,743. The Company has not generated any product revenues and has not achieved profitable operations. There is no assurance that profitable operations will ever be achieved, and, if achieved, will be sustained on a continuing basis. In addition, development activities, clinical and preclinical testing, and commercialization of the Company’s products will require significant additional financing. The future viability of the Company is dependent on its ability to generate cash from operating activities or to raise additional capital to finance its operations. The Company’s failure to raise capital as and when needed could have a negative impact on its financial condition and ability to pursue its business strategies.

Summary of Significant Accounting Policies	6 Months Ended
Summary of Significant Accounting Policies	Jun. 30, 2016
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). The financial statements include the consolidated accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions have been eliminated. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates. Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of June 30, 2016, the condensed consolidated statements of operations and comprehensive loss for the three and six months ended June 30, 2016 and 2015, the condensed consolidated statement of stockholders’ equity for the six months ended June 30, 2016, and the condensed consolidated statements of cash flows for the six months ended June 30, 2016 and 2015 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual financial statements contained in the Company’s annual report on Form 10-K filed with the SEC on March 23, 2016 and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of June 30, 2016, the results of its operations and comprehensive loss for the three and six months ended June 30, 2016 and 2015 and its cash flows for the six months ended June 30, 2016 and 2015. The condensed consolidated balance sheet data as of December 31, 2015 was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States. The financial data and other information disclosed in these notes related to the three and six months ended June 30, 2016 and 2015 are unaudited. The results for the three and six months ended June 30, 2016 are not necessarily indicative of results to be expected for the year ending December 31, 2016, any other interim periods, or any future year or period. The unaudited interim financial statements of the Company included herein have been prepared, pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto for the year ended December 31, 2015 included in the Company’s annual report on Form 10-K filed with the SEC on March 23, 2016. Significant Accounting Policies The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2015 included in the Company’s annual report on Form 10-K filed with the SEC on March 23, 2016. Since the date of such financial statements, there have been no changes to the Company’s significant accounting policies. Assets Held for Sale In order for an asset to be classified as held for sale there must be an active program to market the asset, and it must be probable the asset will be disposed of within one year. The carrying value of an asset held for sale is reported at the lower of its carrying value or its fair value less costs to sell. No additional depreciation expense is recognized once an asset is classified as held for sale. All current and historical balance sheet information for the Company’s assets held for sale is included in prepaid expenses and other current assets in the accompanying condensed consolidated balance sheets. As of June 30, 2016 and December 31, 2015, $216 in assets were classified as held for sale. Recently Issued Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments-Credit Losses (Topic 326). This ASU introduces a new model for recognizing credit losses on financial instruments based upon estimated expected credit losses. ASU 2016-13 will apply to loans, accounts receivable, financial assets measured at amortized cost and at fair value through other comprehensive income, loan commitments and certain off-balance sheet credit exposures. ASU 2016-13 is effective for annual reporting periods beginning after December 15, 2019, including interim periods within those years, and early adoption will be permitted. The Company is assessing the potential impact of ASU 2016-13 on its consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting. This ASU requires all tax effects of share-based payment settlements to be recorded through the income statement. Currently, tax benefits in excess of compensation cost, or “windfalls”, are recorded in equity, and tax deficiencies, or “shortfalls”, are recorded to equity to the extent of previous windfalls, and then to the income statement. In addition, under the new guidance, companies will be permitted to make a policy election to recognize the impact of forfeitures either when they occur, or on an estimated basis. Finally, this update simplifies withholding requirements to allow companies to withhold up to an employee’s maximum tax rate without resulting in liability classification for the award. ASU 2016-09 is effective for annual reporting periods beginning after December 15, 2016, and early adoption is permitted. The Company has adopted the provisions of this standard early, the impact of which on its consolidated financial statements was not significant.

Fair Value of Financial Assets and Liabilities

6 Months Ended

Jun. 30, 2016

Fair Value of Financial Assets and Liabilities

Fair Value of Financial Assets and Liabilities

3. Fair Value of Financial Assets and Liabilities

The following tables present information about the Company’s assets and liabilities measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values:


	Fair Value Measurements as of June 30, 2016
	Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents	$	27,708	$	4,007	$	—	$	31,715
Marketable securities		—		62,195		—		62,195
Total	$	27,708	$	66,202	$	—	$	93,910


	Fair Value Measurements as of December 31,
	2015 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents	$	8,810	$	250	$	—	$	9,060
Marketable securities		—		82,187		—		82,187
Total	$	8,810	$	82,437	$	—	$	91,247

As of June 30, 2016 and December 31, 2015, the Company’s cash equivalents consisted of investments with maturities of less than three months and included a money market fund, which was valued based upon Level 1 inputs, and commercial paper and asset-backed securities. In determining the fair value of its Level 2 investments the Company relied on quoted prices for identical securities in markets that are not active. These quoted prices were obtained by the Company with the assistance of a third-party pricing service based on available trade, bid and other observable market data for identical securities. Quarterly, the Company compares the quoted prices obtained from the third-party pricing service to other available independent pricing information to validate the reasonableness of the quoted prices provided. The Company evaluates whether adjustments to third-party pricing is necessary and, historically, the Company has not made adjustments to quoted prices obtained from the third-party pricing service. During the six months ended June 30, 2016 and the year ended December 31, 2015, there were no transfers between Level 1, Level 2 and Level 3.

As of June 30, 2016 and December 31, 2015, the fair value of the Company’s available for sale marketable securities by type of security was as follows:


	June 30, 2016
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gain		Loss		Value

Marketable securities:
Corporate debt securities	$	34,352	$	6	$	(10)	$	34,348
Commercial paper		4,477		—		—		4,477
Asset-backed securities		8,329		1		(2)		8,328
U.S. government agency debt securities		15,035		7		—		15,042
Total marketable securities	$	62,193	$	14	$	(12)	$	62,195


	December 31, 2015
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gain		Loss		Value
Marketable securities:
Corporate debt securities	$	46,270	$	—	$	(125)	$	46,145
Commercial paper		9,789		—		—		9,789
Asset-backed securities		6,234		—		(14)		6,220
U.S. government agency debt securities		20,048		—		(15)		20,033
Total marketable securities	$	82,341	$	—	$	(154)	$	82,187

As of June 30, 2016 and December 31, 2015, the Company’s investments in corporate debt securities had credit ratings of A and above and remaining maturities of less than 12 months and less than 15 months, respectively.

- 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

Property and Equipment, Net

6 Months Ended

Jun. 30, 2016

Property and Equipment, Net

Property and Equipment, Net

4. Property and Equipment, Net

Property and equipment, net consisted of the following:


	June 30,		December 31,
	2016		2015
Computer equipment	$	318	$	262
Manufacturing equipment		119		101
Furniture and fixtures		87		39
Property and equipment, gross		524		402
Less: Accumulated depreciation		(90)		(42)
Property and equipment, net	$	434	$	360

Depreciation expense was $27 and $22 for the three months ended June 30, 2016 and 2015, respectively, and was $48 and $25 for the six months ended June 30, 2016 and 2015, respectively.

Accrued Expenses

6 Months Ended

Jun. 30, 2016

Accrued Expenses

Accrued Expenses

5. Accrued Expenses

Accrued expenses consisted of the following:


	June 30,		December 31,
	2016		2015
Research and development expenses	$	1,238	$	123
Employee-related expenses		699		—
Licensing fees		—		250
Vixen contract payable		100		—
Professional fees		98		283
Other		63		89
Total accrued expenses	$	2,198	$	745

Stockholders' Equity (Deficit)	6 Months Ended
Stockholders' Equity (Deficit)	Jun. 30, 2016
Stockholders' Equity (Deficit)
Stockholders' Equity (Deficit)	6. Stockholders’ Equity Preferred Stock As of June 30, 2016 and December 31, 2015, the Company’s amended and restated certificate of incorporation authorized the Company to issue 10,000,000 shares of undesignated preferred stock. No shares of preferred stock were outstanding as of June 30, 2016 or December 31, 2015. Common Stock As of June 30, 2016 and December 31, 2015, the Company’s amended and restated certificate of incorporation authorized the Company to issue 100,000,000 shares of $0.00001 par value common stock. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are entitled to receive dividends, as may be declared by the board of directors, if any, subject to any preferential dividend rights of any series of preferred stock that may be outstanding. No dividends have been declared through June 30, 2016.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

+ Details

Stock-Based Awards

6 Months Ended

Jun. 30, 2016

Stock-Based Awards

Stock-Based Awards

7. Stock‑Based Awards

2012 Equity Compensation Plan

Upon the 2015 Equity Incentive Plan (the “2015 Plan”), described below, becoming effective, no further grants may be made under the 2012 Equity Compensation Plan, as amended and restated (the “2012 Plan”).

The Company granted a total of 1,140,524 stock options under the 2012 Plan, of which 1,132,891 were outstanding as of June 30, 2016 and all of which were outstanding as of December 31, 2015. Stock options granted under the 2012 Plan vest over four years and expire after ten years. As required, the exercise price for the stock options granted under the 2012 Plan was not less than the fair value of common shares as determined by the Company as of the date of grant.

2015 Equity Incentive Plan

On September 15, 2015, the Company’s board of directors adopted and on September 16, 2015, the Company’s stockholders approved the 2015 Plan, which became effective in connection with the IPO in October 2015. The 2015 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit (“RSU”) awards, performance stock awards, cash-based awards and other stock-based awards. The number of shares initially reserved for issuance under the 2015 Plan was 1,643,872 shares of common stock. The number of shares of common stock that may be issued under the 2015 Plan will automatically increase on January 1 of each year, beginning on January 1, 2016 and ending on January 1, 2025, in an amount equal to the lesser of (i) 4.0% of the shares of the Company’s common stock outstanding on December 31 of the preceding calendar year or (ii) an amount determined by the Company’s board of directors. The shares of common stock underlying any awards that expire, are otherwise terminated, settled in cash or repurchased by the Company under the 2015 Plan and the 2012 Plan will be added back to the shares of common stock available for issuance under the 2015 Plan. As of January 1, 2016, the number of shares of common stock that may be issued under the 2015 Plan was automatically increased by 806,300 shares. As of June 30, 2016, 1,587,277 shares remained available for grant under the 2015 Plan.

Stock Option Valuation

The weighted average assumptions the Company used to estimate the fair value of stock options granted during the six months ended June 30, 2016 were as follows:


	Six Months Ended
	June 30, 2016

Risk-free interest rate	1.44	%
Expected term (in years)	6.6
Expected volatility	96.90	%
Expected dividend yield	0	%

No stock options were granted during the six months ended June 30, 2015.

The Company recognizes compensation expense for awards over their vesting period. Compensation expense for awards includes the impact of forfeitures in the period when they occur.

Stock Options

The following table summarizes stock option activity from January 1, 2016 through June 30, 2016:


					Weighted
			Weighted		Average
			Average		Remaining	Aggregate
	Number		Exercise		Contractual	Intrinsic
	of Shares		Price		Term	Value
					(in years)
Outstanding as of December 31, 2015	1,738,524		$	13.23	9.51	$	24,722
Granted	182,528			19.97
Exercised	(5,000)			0.41
Forfeited and canceled	(2,633)			5.99
Outstanding as of June 30, 2016	1,913,419		$	13.92	9.09	$	14,182
Options vested and expected to vest as of June 30, 2016	1,913,419		$	13.92	9.09	$	14,182
Options exercisable as of June 30, 2016	208,073	(1)	$	1.36	8.24	$	3,561

(1)

All options granted under the 2012 Plan are exercisable immediately, subject to a repurchase right in the Company’s favor that lapses as the option vests. This amount reflects the number of shares under options that were vested, as opposed to exercisable, as of June 30, 2016.

The weighted average grant‑date fair value of stock options granted during the six months ended June 30, 2016 was $15.79 per share.

The intrinsic value of a stock option is calculated as the difference between the exercise price of the stock option and the fair value of the underlying common stock, and cannot be less than zero.

Restricted Stock Units

The following table summarizes RSU activity from January 1, 2016 through June 30, 2016:


		Weighted
		Average
		Grant Date
	Number	Fair Value
	of Shares	Per Share
Outstanding as of December 31, 2015	53,800	$	28.68
Granted	31,200		20.26
Vested	—		—
Forfeited and cancelled	—		—
Outstanding as of June 30, 2016	85,000	$	25.59

The Company did not grant RSUs during the six months ended June 30, 2015.

Stock‑Based Compensation

The following table summarizes stock‑based compensation expense recorded by the Company for the three and six months ended June 30, 2016 and 2015:



	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
Research and development	$	533	$	14	$	954	$	27
General and administrative		821		28		1,622		58
	$	1,354	$	42	$	2,576	$	85

As of June 30, 2016, the Company had unrecognized stock‑based compensation expense for stock options and RSUs of $17,560 and $1,903, respectively, which is expected to be recognized over weighted average periods of 3.34 years and 3.57 years, respectively.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References + Details

Net Loss per Share

6 Months Ended

Jun. 30, 2016

Net Loss per Share

Net Loss per Share

8. Net Loss per Share

Basic and diluted net loss per share attributable to common stockholders is summarized in the following table:


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2016		2015		2016		2015
Numerator:
Net loss	$	(12,871)	$	(2,594)	$	(25,910)	$	(5,217)
Accretion of redeemable convertible preferred stock		—		(676)		—		(1,333)
Net loss attributable to common stockholders	$	(12,871)	$	(3,270)	$	(25,910)	$	(6,550)
Denominator:
Weighted average shares of common stock outstanding		20,663,088		2,730,427		20,417,301		2,730,427
Less: Weighted average shares of unvested restricted common stock outstanding		—		(575,474)		—		(575,474)
Weighted average common shares outstanding used in calculating net loss per share attributable to common stockholders, basic and diluted		20,663,088		2,154,953		20,417,301		2,154,953
Net loss per share attributable to common stockholders, basic and diluted	$	(0.62)	$	(1.52)	$	(1.27)	$	(3.04)

The Company’s potentially dilutive securities, which included stock options, RSUs, preferred stock and shares of restricted common stock that were issued but not yet vested, have been excluded from the computation of diluted net loss per share since the effect would be to reduce the net loss per share. Therefore, the weighted average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The following table presents potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders for both the three and six months ended June 30, 2016 and 2015. All share amounts presented in the table below represent the total number outstanding as of June 30.


	2016	2015

Stock options to purchase common stock	1,913,419	500,262
Restricted stock unit awards	85,000	—
Unvested restricted common stock	—	519,684
Convertible preferred stock (as converted to common stock)	—	7,924,919
	1,998,419	8,944,865

Commitments and Contingencies

6 Months Ended

Jun. 30, 2016

Commitments and Contingencies

Commitments and Contingencies

9. Commitments and Contingencies

Sublease

In August 2013, the Company entered into a sublease agreement with a related party (see Note 10) for its office space with a term ending on November 30, 2016. As part of an amendment to the sublease agreement entered into in December 2014, the Company increased the amount of office space to be subleased and agreed to new monthly terms commencing in January 2015. On August 14, 2015, the Company further amended its sublease agreement to increase the square footage of the space and to extend the term of the lease to November 2019. Effective December 1, 2015, the Company further amended its sublease agreement to increase the square footage and agreed to new monthly sublease terms. Rent expense under operating leases was $60 and $26 for the three months ended June 30, 2016 and 2015, respectively, and was $112 and $52 for the six months ended June 30, 2016 and 2015, respectively. The Company recognizes rent expense on a straight-line basis over the lease period and has accrued for rent expense incurred but not yet paid.

As of June 30, 2016, future minimum lease payments under the sublease were as follows:


Years Ending December 31,
2016	$	129
2017		263
2018		268
2019		251
2020		—
Total	$	911

Related Party Transactions

6 Months Ended

Jun. 30, 2016

Related Party Transactions

Related Party Transactions

10. Related Party Transactions

In August 2013, the Company entered into a sublease agreement with NeXeption, Inc. ("NeXeption"), which was subsequently amended in December 2014 and August 2015. In August 2015, pursuant to an Assignment and Assumption Agreement, NeXeption, Inc. assigned all interests, rights, duties and obligations under the sublease to NST Consulting, LLC, a wholly owned subsidiary of NST, LLC. Mr. Stephen Tullman, the chairman of the Company’s board of directors, was an executive officer of NeXeption and is also the manager of NST Consulting, LLC and NST, LLC. Total payments made under the sublease during the three months ended June 30, 2016 and 2015 were $56 and $35, respectively, and during the six months ended June 30, 2016 and 2015 were $115 and $52, respectively.

In February 2014, the Company entered into a services agreement with NST, LLC (the “NST services agreement”), pursuant to which NST, LLC provided certain pharmaceutical development, management and other administrative services to the Company. Under the same agreement, the Company also provided services to another company under common control with the Company and NST LLC and was reimbursed by NST LLC for those services. In addition to Mr. Tullman’s role as manager of NST, LLC, several of the Company’s executive officers are members of NST, LLC.

The NST services agreement was amended in January 2015 pursuant to which NST, LLC assigned all interests, rights, duties and obligations under the NST services agreement to NST Consulting, LLC. Under the agreement, as amended, NST Consulting, LLC provides services to the Company and the Company provides services to another company under common control with the Company and NST Consulting, LLC. The NST services agreement was further amended in August 2015 and November 2015 to adjust the amount of services the Company is obligated to provide to NST Consulting, LLC and the amount of services NST Consulting, LLC is obligated to provide to the Company. The Company may offset any payments owed by the Company to NST Consulting, LLC against payments that are owed by NST Consulting, LLC to the Company for the provision of personnel, including consultants, to the Company.

During the three and six months ended June 30, 2016 and 2015, amounts included in the consolidated statement of operations for the NST services agreement are summarized in the following table:


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2016		2015		2016		2015
Services provided by NST Consulting, LLC	$	79	$	129	$	158	$	253
Services provided to NST Consulting, LLC		(15)		(69)		(30)		(117)
General and administrative expense, net	$	64	$	60	$	128	$	136

Services provided by NST Consulting, LLC	$	60	$	—	$	121	$	—
Services provided to NST Consulting, LLC		(21)		(63)		(42)		(127)
Research and development expense, net	$	39	$	(63)	$	79	$	(127)

Services provided by NST Consulting, LLC	$	139	$	129	$	279	$	253
Services provided to NST Consulting, LLC		(36)		(132)		(72)		(244)
Total, net	$	103	$	(3)	$	207	$	9


Payments made to NST	$	117	$	—	$	175	$	15

The Company did not have any open invoices payable to NST Consulting, LLC under the NST services agreement as of either June 30, 2016 or December 31, 2015.

Agreements Related to Intellectual Property	6 Months Ended
Agreements Related to Intellectual Property	Jun. 30, 2016
Agreements Related to Intellectual Property
Agreements Related to Intellectual Property	11. Agreements Related to Intellectual Property Assignment Agreement and Finder’s Services Agreement In August 2012, the Company entered into an assignment agreement with the Estate of Mickey Miller, or the Miller Estate, under which the Company acquired some of the intellectual property rights covering A-101. In connection with obtaining the assignment of the intellectual property from the Miller Estate, the Company also entered into a separate finder’s services agreement with KPT Consulting, LLC. In February 2016, under the terms of the assignment agreement and the finder’s services agreement, the Company made a one-time milestone payment of $300 upon the dosing of the first subject with A-101 in the Company’s Phase 3 clinical trial. The payment was recorded as general and administrative expense during the six months ended June 30, 2016. Under the finder’s services agreement, the Company is obligated to make an additional milestone payment of $1,000 upon the submission of an NDA for A-101 and regulatory milestones and up to $4,500 upon the achievement of specified commercial milestones. Under each of the assignment agreement and the finder’s services agreement, the Company is also obligated to pay royalties on sales of A-101 or related products, at low single-digit percentages of net sales, subject to reduction in specified circumstances. The Company has not made any royalty payments to date under either agreement. Both agreements will terminate upon the expiration of the last pending, viable patent claim of the patents acquired under the assignment agreement, but no sooner than 15 years from the effective date of the agreements. Stock Purchase Agreement with Vixen Pharmaceuticals, Inc. and License Agreement with Columbia University On March 24, 2016, the Company entered into a stock purchase agreement (the “Vixen Agreement”) with Vixen, JAK1, LLC, JAK2, LLC and JAK3, LLC (together with JAK1, LLC and JAK2, LLC, the “Selling Stockholders”) and Shareholder Representative Services LLC, a Colorado limited liability company, solely in its capacity as the representative of the Selling Stockholders. Pursuant to the Vixen Agreement, the Company acquired all shares of Vixen’s capital stock from the Selling Stockholders (the “Vixen Acquisition”). Following the Vixen Acquisition, Vixen will continue as a wholly owned subsidiary of the Company. Pursuant to the Vixen Agreement, the Company paid $600 upfront and issued an aggregate of 159,420 shares of the Company’s common stock to the Selling Stockholders. The Company is obligated to make annual payments of $100 on March 24th of each year, through March 24, 2022, with such amounts being creditable against specified future payments that may be paid under the Vixen Agreement. The Company is obligated to make aggregate payments of up to $18,000 to the Selling Stockholders upon the achievement of specified pre-commercialization milestones for three products in the United States, the European Union and Japan, and aggregate payments of up to $22,500 upon the achievement of specified commercial milestones. With respect to any commercialized products covered by the Vixen Agreement, the Company is obligated to pay low single-digit royalties on net sales, subject to specified reductions, limitations and other adjustments, until the date that all of the patent rights for that product have expired, as determined on a country-by-country and product-by-product basis or, in specified circumstances, ten years from the first commercial sale of such product. If the Company sublicenses any of Vixen’s patent rights and know-how acquired pursuant to the Vixen Agreement, the Company will be obligated to pay a portion of any consideration the Company receives from such sublicenses in specified circumstances. As a result of the transaction with Vixen, the Company became party to the Exclusive License Agreement, by and between Vixen and the Trustees of Columbia University in the City of New York (“Columbia”), dated as of December 31, 2015 (the “License Agreement”). Under the License Agreement, the Company is obligated to pay Columbia an annual license fee of $10, subject to specified adjustments for patent expenses incurred by Columbia and creditable against any royalties that may be paid under the License Agreement. The Company is also obligated to pay up to an aggregate of $11,600 upon the achievement of specified commercial milestones, including specified levels of net sales of products covered by Columbia patent rights and/or know-how, and royalties at a sub-single-digit percentage of annual net sales of products covered by Columbia patent rights and/or know-how, subject to specified adjustments. If the Company sublicenses any of Columbia’s patent rights and know-how acquired pursuant to the License Agreement, it will be obligated to pay Columbia a portion of any consideration received from such sublicenses in specified circumstances. The royalties, as determined on a country-by-country and product-by-product basis, are payable until the date that all of the patent rights for that product have expired, the expiration of any market exclusivity period granted by a regulatory body or, in specified circumstances, ten years from the first commercial sale of such product. The License Agreement terminates on the date of expiration of all royalty obligations thereunder unless earlier terminated by either party for a material breach, subject to a specified cure period. The Company may also terminate the License Agreement without cause at any time upon advance written notice to Columbia. The Company accounted for the transaction with Vixen as an asset acquisition as the arrangement did not meet the definition of a business pursuant to the guidance prescribed in Accounting Standards Codification Topic 805, Business Combinations. The Company concluded the transaction with Vixen did not meet the definition of a business because the transaction principally resulted in the acquisition of the License Agreement. The Company did not acquire tangible assets, processes, protocols or operating systems. In addition, at the time of the transaction, there were no activities being conducted related to the licensed patents. The Company expensed the acquired intellectual property as of the acquisition date on the basis that the cost of intangible assets purchased from others for use in research and development activities, and that have no alternative future uses, are expensed at the time the costs are incurred. Accordingly, the Company recorded the $600 upfront payment, the fair value of the shares of common stock issued of $2,355, and the present value of the six non-contingent annual payments as research and development expense in the six months ended June 30, 2016. Additionally, the Company will record as expense any contingent milestone payments or royalties in the period in which such liabilities are incurred.

Income Taxes	6 Months Ended
Income Taxes	Jun. 30, 2016
Income Taxes
Income Taxes	12. Income Taxes The Company did not record a federal or state income tax benefit for losses incurred during the three and six months ended June 30, 2016 and 2015 due to the Company’s conclusion that a valuation allowance is required.

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Jun. 30, 2016
Summary of Significant Accounting Policies
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). The financial statements include the consolidated accounts of the Company and its wholly-owned subsidiaries. All intercompany transactions have been eliminated.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these financial statements include, but are not limited to, research and development expenses and the valuation of stock-based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results could differ from the Company’s estimates.
Unaudited Interim Financial Information Policy [Policy TextBlock]	Unaudited Interim Financial Information The accompanying condensed consolidated balance sheet as of June 30, 2016, the condensed consolidated statements of operations and comprehensive loss for the three and six months ended June 30, 2016 and 2015, the condensed consolidated statement of stockholders’ equity for the six months ended June 30, 2016, and the condensed consolidated statements of cash flows for the six months ended June 30, 2016 and 2015 are unaudited. The unaudited interim condensed consolidated financial statements have been prepared on the same basis as the audited annual financial statements contained in the Company’s annual report on Form 10-K filed with the SEC on March 23, 2016 and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of June 30, 2016, the results of its operations and comprehensive loss for the three and six months ended June 30, 2016 and 2015 and its cash flows for the six months ended June 30, 2016 and 2015. The condensed consolidated balance sheet data as of December 31, 2015 was derived from audited financial statements but does not include all disclosures required by accounting principles generally accepted in the United States. The financial data and other information disclosed in these notes related to the three and six months ended June 30, 2016 and 2015 are unaudited. The results for the three and six months ended June 30, 2016 are not necessarily indicative of results to be expected for the year ending December 31, 2016, any other interim periods, or any future year or period. The unaudited interim financial statements of the Company included herein have been prepared, pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto for the year ended December 31, 2015 included in the Company’s annual report on Form 10-K filed with the SEC on March 23, 2016.
Significant Accounting Policies [Policy TextBlock]	Significant Accounting Policies The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2015 included in the Company’s annual report on Form 10-K filed with the SEC on March 23, 2016. Since the date of such financial statements, there have been no changes to the Company’s significant accounting policies.
Assets Held For Sale, Policy [Policy Text Block]	Assets Held for Sale In order for an asset to be classified as held for sale there must be an active program to market the asset, and it must be probable the asset will be disposed of within one year. The carrying value of an asset held for sale is reported at the lower of its carrying value or its fair value less costs to sell. No additional depreciation expense is recognized once an asset is classified as held for sale. All current and historical balance sheet information for the Company’s assets held for sale is included in prepaid expenses and other current assets in the accompanying condensed consolidated balance sheets. As of June 30, 2016 and December 31, 2015, $216 in assets were classified as held for sale.
Recently Issued And Adopted Accounting Pronouncements	Recently Issued Accounting Pronouncements In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-13, Financial Instruments-Credit Losses (Topic 326). This ASU introduces a new model for recognizing credit losses on financial instruments based upon estimated expected credit losses. ASU 2016-13 will apply to loans, accounts receivable, financial assets measured at amortized cost and at fair value through other comprehensive income, loan commitments and certain off-balance sheet credit exposures. ASU 2016-13 is effective for annual reporting periods beginning after December 15, 2019, including interim periods within those years, and early adoption will be permitted. The Company is assessing the potential impact of ASU 2016-13 on its consolidated financial statements. In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting. This ASU requires all tax effects of share-based payment settlements to be recorded through the income statement. Currently, tax benefits in excess of compensation cost, or “windfalls”, are recorded in equity, and tax deficiencies, or “shortfalls”, are recorded to equity to the extent of previous windfalls, and then to the income statement. In addition, under the new guidance, companies will be permitted to make a policy election to recognize the impact of forfeitures either when they occur, or on an estimated basis. Finally, this update simplifies withholding requirements to allow companies to withhold up to an employee’s maximum tax rate without resulting in liability classification for the award. ASU 2016-09 is effective for annual reporting periods beginning after December 15, 2016, and early adoption is permitted. The Company has adopted the provisions of this standard early, the impact of which on its consolidated financial statements was not significant.

Fair Value of Financial Assets and Liabilities (Tables)

6 Months Ended

Jun. 30, 2016

Fair Value of Financial Assets and Liabilities

Schedule of assets and liabilities measured at fair value on a recurring basis


	Fair Value Measurements as of June 30, 2016
	Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents	$	27,708	$	4,007	$	—	$	31,715
Marketable securities		—		62,195		—		62,195
Total	$	27,708	$	66,202	$	—	$	93,910


	Fair Value Measurements as of December 31,
	2015 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents	$	8,810	$	250	$	—	$	9,060
Marketable securities		—		82,187		—		82,187
Total	$	8,810	$	82,437	$	—	$	91,247

Schedule of the fair value of available for sale marketable securities by type of security


	June 30, 2016
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gain		Loss		Value

Marketable securities:
Corporate debt securities	$	34,352	$	6	$	(10)	$	34,348
Commercial paper		4,477		—		—		4,477
Asset-backed securities		8,329		1		(2)		8,328
U.S. government agency debt securities		15,035		7		—		15,042
Total marketable securities	$	62,193	$	14	$	(12)	$	62,195


	December 31, 2015
			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gain		Loss		Value
Marketable securities:
Corporate debt securities	$	46,270	$	—	$	(125)	$	46,145
Commercial paper		9,789		—		—		9,789
Asset-backed securities		6,234		—		(14)		6,220
U.S. government agency debt securities		20,048		—		(15)		20,033
Total marketable securities	$	82,341	$	—	$	(154)	$	82,187

Property and Equipment, Net (Tables)

6 Months Ended

Jun. 30, 2016

Property and Equipment, Net

Schedule of property and equipment, net


	June 30,		December 31,
	2016		2015
Computer equipment	$	318	$	262
Manufacturing equipment		119		101
Furniture and fixtures		87		39
Property and equipment, gross		524		402
Less: Accumulated depreciation		(90)		(42)
Property and equipment, net	$	434	$	360

Accrued Expenses (Tables)

6 Months Ended

Jun. 30, 2016

Accrued Expenses

Schedule of accrued expenses


	June 30,		December 31,
	2016		2015
Research and development expenses	$	1,238	$	123
Employee-related expenses		699		—
Licensing fees		—		250
Vixen contract payable		100		—
Professional fees		98		283
Other		63		89
Total accrued expenses	$	2,198	$	745

Stock-Based Awards (Tables)

6 Months Ended

Jun. 30, 2016

Stock-Based Awards

Assumptions used to determine fair value of stock options granted


	Six Months Ended
	June 30, 2016

Risk-free interest rate	1.44	%
Expected term (in years)	6.6
Expected volatility	96.90	%
Expected dividend yield	0	%

Summary of stock option activity


					Weighted
			Weighted		Average
			Average		Remaining	Aggregate
	Number		Exercise		Contractual	Intrinsic
	of Shares		Price		Term	Value
					(in years)
Outstanding as of December 31, 2015	1,738,524		$	13.23	9.51	$	24,722
Granted	182,528			19.97
Exercised	(5,000)			0.41
Forfeited and canceled	(2,633)			5.99
Outstanding as of June 30, 2016	1,913,419		$	13.92	9.09	$	14,182
Options vested and expected to vest as of June 30, 2016	1,913,419		$	13.92	9.09	$	14,182
Options exercisable as of June 30, 2016	208,073	(1)	$	1.36	8.24	$	3,561

(1)

Summary of RSU activity


		Weighted
		Average
		Grant Date
	Number	Fair Value
	of Shares	Per Share
Outstanding as of December 31, 2015	53,800	$	28.68
Granted	31,200		20.26
Vested	—		—
Forfeited and cancelled	—		—
Outstanding as of June 30, 2016	85,000	$	25.59

Stock-based compensation expense



	Three Months Ended June 30,				Six Months Ended June 30,
	2016		2015		2016		2015
Research and development	$	533	$	14	$	954	$	27
General and administrative		821		28		1,622		58
	$	1,354	$	42	$	2,576	$	85

Net Loss per Share (Tables)

6 Months Ended

Jun. 30, 2016

Net Loss per Share

Basic and diluted net loss per share attributable to common stockholders


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2016		2015		2016		2015
Numerator:
Net loss	$	(12,871)	$	(2,594)	$	(25,910)	$	(5,217)
Accretion of redeemable convertible preferred stock		—		(676)		—		(1,333)
Net loss attributable to common stockholders	$	(12,871)	$	(3,270)	$	(25,910)	$	(6,550)
Denominator:
Weighted average shares of common stock outstanding		20,663,088		2,730,427		20,417,301		2,730,427
Less: Weighted average shares of unvested restricted common stock outstanding		—		(575,474)		—		(575,474)
Weighted average common shares outstanding used in calculating net loss per share attributable to common stockholders, basic and diluted		20,663,088		2,154,953		20,417,301		2,154,953
Net loss per share attributable to common stockholders, basic and diluted	$	(0.62)	$	(1.52)	$	(1.27)	$	(3.04)

Potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders


	2016	2015

Stock options to purchase common stock	1,913,419	500,262
Restricted stock unit awards	85,000	—
Unvested restricted common stock	—	519,684
Convertible preferred stock (as converted to common stock)	—	7,924,919
	1,998,419	8,944,865

Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2016

Commitments and Contingencies

Schedule of future minimum lease payments under the sublease


Years Ending December 31,
2016	$	129
2017		263
2018		268
2019		251
2020		—
Total	$	911

Related Party Transactions (Tables)

6 Months Ended

Jun. 30, 2016

Related Party Transactions

Schedule of gross expenses incurred


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2016		2015		2016		2015
Services provided by NST Consulting, LLC	$	79	$	129	$	158	$	253
Services provided to NST Consulting, LLC		(15)		(69)		(30)		(117)
General and administrative expense, net	$	64	$	60	$	128	$	136

Services provided by NST Consulting, LLC	$	60	$	—	$	121	$	—
Services provided to NST Consulting, LLC		(21)		(63)		(42)		(127)
Research and development expense, net	$	39	$	(63)	$	79	$	(127)

Services provided by NST Consulting, LLC	$	139	$	129	$	279	$	253
Services provided to NST Consulting, LLC		(36)		(132)		(72)		(244)
Total, net	$	103	$	(3)	$	207	$	9


Payments made to NST	$	117	$	—	$	175	$	15

Organization and Nature of Business (Details) - A-101	Jun. 30, 2016 item
Production information
Number of clinical trials completed	3
Number of clinical trials in process	3

Organization and Nature of Business - IPO, Stock Split, Liquidity (Details) $ / shares in Units, $ in Thousands				6 Months Ended
	Jun. 02, 2016 USD ($) $ / shares shares	Oct. 13, 2015 USD ($) $ / shares shares	Sep. 24, 2015	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Initial public offering
Issuance of common stock in connection with private placement, net of offering costs				$ 18,547
Common stock shares issued upon conversion of convertible preferred stock \| shares		11,677,076
Offering costs					$ 895
Reverse stock split			0.2899
Cash, cash equivalents and marketable securities				94,010
Accumulated deficit				$ 68,743		$ 42,833
IPO
Initial public offering
Number of shares issued \| shares		5,000,000
Issuance price (in dollars per share) \| $ / shares		$ 11.00
Issuance of common stock in connection with private placement, net of offering costs		$ 55,000
Offering costs		2,272
Offering proceeds, net of discounts, commissions and expenses		$ 56,550
Exercise of over-allotment option
Initial public offering
Number of shares issued \| shares		750,000
Issuance price (in dollars per share) \| $ / shares		$ 11.00
Issuance of common stock in connection with private placement, net of offering costs		$ 8,250
Offering costs	$ 1,300	$ 4,428
Private Placement [Member]
Initial public offering
Number of shares issued \| shares	1,081,082
Issuance price (in dollars per share) \| $ / shares	$ 18.50
Issuance of common stock in connection with private placement, net of offering costs	$ 20,000
Offering costs	153
Offering proceeds, net of discounts, commissions and expenses	$ 18,547

Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Summary of Significant Accounting Policies
Assets held for sale, maximum holding period	1 year
Assets held for sale	$ 216	$ 216

Fair Value of Financial Assets and Liabilities (Detail) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Assets:
Marketable securities	$ 62,195	$ 82,187
Transfers from Level 1 to Level 2	0	0
Transfers from Level 2 to Level 1	0	0
Transfers into or out of Level 3	0	0
Recurring
Assets:
Cash equivalents	31,715	9,060
Marketable securities	62,195	82,187
Total assets measured at fair value	93,910	91,247
Recurring \| Level 1
Assets:
Cash equivalents	27,708	8,810
Total assets measured at fair value	27,708	8,810
Recurring \| Level 2
Assets:
Cash equivalents	4,007	250
Marketable securities	62,195	82,187
Total assets measured at fair value	$ 66,202	$ 82,437

Fair Value of Financial Assets and Liabilities - by type (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Marketable securities:
Amortized Cost	$ 62,193	$ 82,341
Gross Unrealized Gain	14
Gross Unrealized Loss	(12)	(154)
Fair Value	62,195	82,187
Corporate debt securities
Marketable securities:
Amortized Cost	34,352	46,270
Gross Unrealized Gain	6
Gross Unrealized Loss	(10)	(125)
Fair Value	$ 34,348	$ 46,145
Corporate debt securities \| Maximum
Marketable securities:
Remaining term of maturities (in months)	12 months	15 months
Commercial paper
Marketable securities:
Amortized Cost	$ 4,477	$ 9,789
Fair Value	4,477	9,789
Asset-backed Securities [Member]
Marketable securities:
Amortized Cost	8,329	6,234
Gross Unrealized Gain	1
Gross Unrealized Loss	(2)	(14)
Fair Value	8,328	6,220
U.S. government agency debt securities
Marketable securities:
Amortized Cost	15,035	20,048
Gross Unrealized Gain	7
Gross Unrealized Loss		(15)
Fair Value	$ 15,042	$ 20,033

Property and Equipment, Net (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Property and Equipment, net
Property and equipment	$ 524		$ 524		$ 402
Less: accumulated depreciation	(90)		(90)		(42)
Property and equipment, net	434		434		360
Depreciation expense	27	$ 22	48	$ 25
Computer equipment
Property and Equipment, net
Property and equipment	318		318		262
Manufacturing equipment
Property and Equipment, net
Property and equipment	119		119		101
Furniture and Fixtures [Member]
Property and Equipment, net
Property and equipment	$ 87		$ 87		$ 39

Accrued Expenses (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Accrued Expenses
Research and development expenses	$ 1,238	$ 123
Employee-related expenses	699
Licensing fees		250
Vixen contract payable.	100
Professional fees	98	283
Other	63	89
Total accrued expenses	$ 2,198	$ 745

Stockholders' Equity (Details)	6 Months Ended
Stockholders' Equity (Details)	Jun. 30, 2016 USD ($) Vote $ / shares shares	Dec. 31, 2015 $ / shares shares
Stockholders' Equity (Deficit)
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares outstanding	0	0
Common stock shares authorized	100,000,000	100,000,000
Common stock par value (in dollars per share) \| $ / shares	$ 0.00001	$ 0.00001
Number of votes per share \| Vote	1
Dividends declared \| $	$ 0

Stock-Based Awards (Details) - USD ($) $ / shares in Units, $ in Thousands		6 Months Ended		12 Months Ended	48 Months Ended
	Jan. 01, 2016	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2015	Sep. 15, 2015
Stock-based awards
Options granted (in shares)		182,528	0
Number of Shares
Number of Shares, beginning balance	1,738,524	1,738,524
Number of Shares, Granted		182,528	0
Number of Shares, Exercised		(5,000)
Number of Shares, Forfeited and canceled		(2,633)
Number of Shares, ending balance		1,913,419		1,738,524	1,738,524
Number of Shares, Options vested and expected to vest		1,913,419
Number of Shares, Options exercisable		208,073
Weighted Average Exercise Price
Weighted Average Exercise Price, beginning balance (in dollars per share)	$ 13.23	$ 13.23
Weighted Average Exercise Price, Granted (in dollars per share)		19.97
Weighted Average Exercise Price, Exercised (in dollars per share)		0.41
Weighted Average Exercise Price, Forfeited and canceled (in dollars per share)		5.99
Weighted Average Exercise Price, ending balance (in dollars per share)		13.92		$ 13.23	$ 13.23
Weighted Average Exercise Price, Options vested and expected to vest (in dollars per share)		13.92
Weighted Average Exercise Price, Options exercisable (in dollars per share)		$ 1.36
Weighted Average Remaining Contractual Term
Weighted Average Remaining Contractual Term (in years)		9 years 1 month 2 days		9 years 6 months 4 days
Weighted Average Remaining Contractual Term, Options vested and expected to vest (in years)		9 years 1 month 2 days
Weighted Average Remaining Contractual Term, Options exercisable (in years)		8 years 2 months 27 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value		$ 14,182		$ 24,722	$ 24,722
Aggregate Intrinsic Value, Options vested and expected to vest		14,182
Aggregate Intrinsic Value, Options exercisable		$ 3,561
Weighted average grant-date fair value of stock options granted (in dollars per share)		$ 15.79
Employee, director and consultant stock options
Stock Option Valuation
Risk-free interest rate (as a percent)		1.44%
Expected term (in years)		6 years 7 months 6 days
Expected volatility (as a percent)		96.90%
Expected dividend yield (as a percent)		0.00%
2012 Equity Compensation Plan
Stock-based awards
Number of shares available for grant		0
Options granted (in shares)		1,140,524			1,140,524
Number of Shares
Number of Shares, beginning balance	1,140,524	1,140,524
Number of Shares, Granted		1,140,524			1,140,524
Number of Shares, ending balance		1,132,891		1,140,524	1,140,524
2012 Equity Compensation Plan \| Employee, director and consultant stock options
Stock-based awards
Term of award (in years)		10 years
Vesting period (in years)		4 years
2015 Equity Incentive Plan
Stock-based awards
Number of shares available for grant		1,587,277
Number of shares authorized						1,643,872
Percentage increase to shares available for grant from common outstanding as of preceding December 31 (as a percent)						4.00%
Additional shares available	806,300

Stock-Based Awards - RSUs (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Weighted Average Grant Date Fair Value Per Share
Unrecognized compensation, RSUs	$ 1,903
Restricted Stock Units (RSUs) [Member]
Weighted Average Grant Date Fair Value Per Share
Weighted average recognition period unrecognized stock-based compensation cost (in years)	3 years 6 months 26 days
2015 Equity Incentive Plan \| Restricted Stock Units (RSUs) [Member]
RSU Activity
Units outstanding, beginning of period	53,800
Granted	31,200	0
Units outstanding, end of period	85,000
Weighted Average Grant Date Fair Value Per Share
Weighted average grant date fair value, beginning balance (in dollars per share)	$ 28.68
Granted, estimated grant-date fair value (in dollars per share)	20.26
Weighted average grant date fair value, ending balance (in dollars per share)	$ 25.59

Stock-Based Awards - Compensation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Stock-based compensation expense
Stock-based compensation expense	$ 1,354	$ 42	$ 2,576	$ 85
Unrecognized stock-based compensation cost, options	17,560		17,560
Unrecognized compensation, RSUs	1,903		1,903
Research and development expense.
Stock-based compensation expense
Stock-based compensation expense	533	14	954	27
General and administrative expense.
Stock-based compensation expense
Stock-based compensation expense	$ 821	$ 28	$ 1,622	$ 58
Employee, director and consultant stock options
Stock-based compensation expense
Weighted average recognition period unrecognized stock-based compensation cost (in years)			3 years 4 months 2 days
Restricted Stock Units (RSUs) [Member]
Stock-based compensation expense
Weighted average recognition period unrecognized stock-based compensation cost (in years)			3 years 6 months 26 days

Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Numerator:
Net loss	$ (12,871)	$ (2,594)	$ (25,910)	$ (5,217)
Accretion of convertible preferred stock to redemption value		(676)		(1,333)
Net loss attributable to common stockholders	$ (12,871)	$ (3,270)	$ (25,910)	$ (6,550)
Denominator:
Weighted average shares of common stock outstanding (in shares)	20,663,088	2,730,427	20,417,301	2,730,427
Less: Weighted average shares of unvested restricted common stock outstanding (in shares)		(575,474)		(575,474)
Weighted average common shares outstanding used in calculating net loss per share attributable to common stockholders, basic and diluted (in shares)	20,663,088	2,154,953	20,417,301	2,154,953
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.62)	$ (1.52)	$ (1.27)	$ (3.04)

Net Loss per Share - Anti-dilution (Details) - shares	6 Months Ended
Net Loss per Share - Anti-dilution (Details) - shares	Jun. 30, 2016	Jun. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders	1,998,419	8,944,865
Employee, director and consultant stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders	1,913,419	500,262
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders	85,000
Restricted common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders		519,684
Convertible preferred stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential common shares excluded from the calculation of diluted net loss per share attributable to common stockholders		7,924,919

Commitments and Contingencies (Details) - Direct sublease agreement - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Lease
Expenses incurred under related party transactions			$ 112	$ 52
Director
Lease
Expenses incurred under related party transactions	$ 60	$ 26
Future minimum lease payments under the sublease
2016	129		129
2017	263		263
2018	268		268
2019	251		251
Total	$ 911		$ 911

Related Party Transaction (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Direct sublease agreement
Related Party Transactions
Expenses incurred under related party transactions			$ 112	$ 52
Direct sublease agreement \| NST, LLC [Member]
Related Party Transactions
Expenses incurred under related party transactions	$ 56	$ 35	115	52
Services agreement
Related Party Transactions
Net expenses (revenues) from related party transactions	103	(3)	207	9
Services agreement \| General and administrative expense.
Related Party Transactions
Net expenses (revenues) from related party transactions	64	60	128	136
Services agreement \| Research and development expense.
Related Party Transactions
Net expenses (revenues) from related party transactions	39	(63)	79	(127)
Services agreement \| NST, LLC [Member]
Related Party Transactions
Expenses incurred under related party transactions	139	129	279	253
Other revenue earned from related party transactions	(36)	(132)	(72)	(244)
Payments made for related party transactions	117		175	15
Services agreement \| NST, LLC [Member] \| General and administrative expense.
Related Party Transactions
Expenses incurred under related party transactions	79	129	158	253
Other revenue earned from related party transactions	(15)	(69)	(30)	(117)
Services agreement \| NST, LLC [Member] \| Research and development expense.
Related Party Transactions
Expenses incurred under related party transactions	60		121
Other revenue earned from related party transactions	(21)	(63)	$ (42)	$ (127)
Director \| Direct sublease agreement
Related Party Transactions
Expenses incurred under related party transactions	$ 60	$ 26

Agreements Related to Intellectual Property (Details) $ in Thousands		3 Months Ended		6 Months Ended
	Mar. 24, 2016 USD ($) item shares	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) installment	Jun. 30, 2015 USD ($)
License Agreement
Upfront payment recorded as research and development expense		$ 9,836	$ 1,793	$ 19,371	$ 3,530
Assignment Agreement and Finder's Services Agreement [Member] \| A-101
License Agreement
Maximum aggregate payments owed upon achievement of specified pre-commercialization milestones		1,000		1,000
Maximum additional payments owed upon achievement of second set of development milestones		$ 4,500		$ 4,500
Term of Agreement, Minimum				15 years
Assignment Agreement and Finder's Services Agreement [Member] \| A-101 \| General and administrative expense.
License Agreement
Milestone payment				$ 300
Stock Purchase Agreement [Member]
License Agreement
Maximum aggregate payments owed upon achievement of specified pre-commercialization milestones	$ 18,000
Maximum additional payments owed upon achievement of second set of development milestones	$ 22,500
Upfront payment recorded as research and development expense				600
Stock Issued During Period, Shares, Purchase of Assets \| shares	159,420
Amount Of Fixed Annual Payment	$ 100
Number Of Products \| item	3
Stock Issued During Period, Value, Purchase of Assets				$ 2,355
Number Of Payments \| installment				6
Period from first commercial product sale that royalties are owed (in years)	10 years
Commercial License Agreement
License Agreement
Maximum additional payments owed upon achievement of second set of development milestones	$ 11,600
Amount Of Fixed Annual Payment	$ 10
Period from first commercial product sale that royalties are owed (in years)	10 years

Income Taxes (Details) - USD ($) $ in Thousands	6 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Jun. 30, 2015
Income Taxes
Federal income tax benefit	$ 0	$ 0
State income tax benefit	$ 0	$ 0