Clearside Biomedical (CLSD) S-1/A 7 Dec 16 IPO registration (amended) Financial data

Document and Entity Information

Document and Entity Information	9 Months Ended
	Sep. 30, 2016
Document And Entity Information [Abstract]
Document Type	S-1/A
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Trading Symbol	CLSD
Entity Registrant Name	Clearside Biomedical, Inc.
Entity Central Index Key	1,539,029
Entity Filer Category	Non-accelerated Filer

Balance sheets

Balance sheets - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 36,876	$ 20,283	$ 8,269
Short-term investments	20,043
Prepaid expenses	662	159	47
Other current assets	73	40	7
Total current assets	57,654	20,482	8,323
Property and equipment, net	110	156	205
Deferred offering costs		410	1,750
Other assets	7	7	21
Total assets	57,771	21,055	10,299
Current liabilities:
Accounts payable	1,347	1,469	1,257
Accrued liabilities	1,556	1,985	1,157
Current portion of long-term debt		1,733
Other current liabilities	25	0
Current portion of deferred rent		9	10
Total current liabilities	2,928	5,196	2,424
Deferred revenue	165	700	200
Deferred rent		3	11
Long-term debt	7,489	4,243
Other non-current liabilities	251	261	42
Total liabilities	10,833	10,400	2,677
Commitments and contingencies
Convertible preferred stock:
Total convertible preferred stock		47,314	26,835
Stockholders' equity (deficit):
Preferred stock, $0.001 par value; 10,000,000 shares authorized and no shares issued at September 30, 2016; no shares authorized or issued at December 31, 2015
Common stock	21	3	2
Additional paid-in capital	102,481	2,701	2,509
Accumulated deficit	(55,559)	(39,363)	(21,724)
Accumulated other comprehensive loss	(5)
Total stockholders' equity (deficit)	46,938	(36,659)	(19,213)
Total liabilities, convertible preferred stock and stockholders' equity (deficit)	$ 57,771	21,055	10,299
Scenario, Previously Reported
Current liabilities:
Other non-current liabilities		258
Series A Preferred Stock
Convertible preferred stock:
Total convertible preferred stock		4,086	4,086
Series A-1 Preferred Stock
Convertible preferred stock:
Total convertible preferred stock		7,900	7,858
Series B Preferred Stock
Convertible preferred stock:
Total convertible preferred stock		15,372	$ 14,891
Series C Preferred Stock
Convertible preferred stock:
Total convertible preferred stock		$ 19,956

Balance sheets (Parenthetical)

Balance sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	0
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.001	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	40,000,000	30,000,000
Common stock, shares, issued	20,545,752	2,659,262	1,816,467
Common stock, shares outstanding	20,545,752	2,659,262	1,816,467
Series A Preferred Stock
Convertible preferred stock, par value	$ 0.001	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	5,198,826	5,198,826
Convertible preferred stock, shares issued	0	5,198,826	5,198,826
Convertible preferred stock, shares outstanding	0	5,198,826	5,198,826
Convertible preferred stock, liquidation preference	$ 0	$ 4,086	$ 4,086
Series A-1 Preferred Stock
Convertible preferred stock, par value	$ 0.001	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	4,373,481	4,373,481
Convertible preferred stock, shares issued	0	4,356,931	4,356,931
Convertible preferred stock, shares outstanding	0	4,356,931	4,356,931
Convertible preferred stock, liquidation preference	$ 0	$ 7,900	$ 7,900
Series B Preferred Stock
Convertible preferred stock, par value	$ 0.001	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	6,066,345	7,413,365
Convertible preferred stock, shares issued	0	6,009,202	6,009,202
Convertible preferred stock, shares outstanding	0	6,009,202	6,009,202
Convertible preferred stock, liquidation preference	$ 0	$ 16,212	$ 16,212
Series C Preferred Stock
Convertible preferred stock, par value	$ 0.001	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	5,274,679
Convertible preferred stock, shares issued	0	5,274,674
Convertible preferred stock, shares outstanding	0	5,274,674
Convertible preferred stock, liquidation preference	$ 0	$ 20,000

Statements of operations and co

Statements of operations and comprehensive loss - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
License revenue	$ 515
Operating expenses:
Research and development	12,484	$ 6,964	$ 10,762	$ 6,692
General and administrative	3,872	5,337	6,555	3,131
Total operating expenses	16,356	12,301	17,317	9,823
Loss from operations	(15,841)	(12,301)	(17,317)	(9,823)
Other income (expense):
Interest expense			(330)	(371)
Interest income			8	5
Total other expense			(322)	(366)
Other income (expense)	(355)	(168)
Net loss	$ (16,196)	$ (12,469)	$ (17,639)	$ (10,189)
Net loss per share of common stock - basic and diluted	$ (1.54)	$ (5.59)	$ (7.54)	$ (5.86)
Weighted average shares outstanding - basic and diluted	10,502,459	2,231,830	2,338,950	1,738,660
Net loss	$ (16,196)	$ (12,469)	$ (17,639)	$ (10,189)
Unrealized loss on available-for-sale investments	(5)
Comprehensive loss	$ (16,201)	$ (12,469)

Statements of stockholders' def

Statements of stockholders' deficit - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]
Beginning balance at Dec. 31, 2013	$ (10,738)	$ 2	$ 796	$ (11,535)
Beginning balance, shares at Dec. 31, 2013		1,583,144
Exercise of stock options	$ 5		5
Exercise of stock options, shares	24,803	24,803
Vesting of restricted stock	$ 6		6
Vesting of restricted stock, shares		208,520
Issuance of warrants to purchase common stock	1,506		1,506
Accretion of stock issuance costs	(231)		(231)
Share-based compensation expense	427		427
Net loss	(10,189)			(10,189)
Ending balance at Dec. 31, 2014	(19,213)	$ 2	2,509	(21,724)
Ending balance, shares at Dec. 31, 2014		1,816,467
Exercise of stock options	$ 14		$ 14
Exercise of stock options, shares	50,980	50,980
Exercise of Series B common stock warrants	(1,000)	1,000	(2,000)
Exercise of Series B common stock warrants , shares		777,612
Vesting of restricted stock, shares		14,203
Accretion of stock issuance costs	$ (525)		$ (525)
Share-based compensation expense	705		705
Net loss	(17,639)			(17,639)
Ending balance at Dec. 31, 2015	$ (36,659)	$ 3	$ 2,701	$ (39,363)
Ending balance, shares at Dec. 31, 2015		2,659,262
Exercise of stock options, shares	1,326
Issuance of warrants to purchase common stock	$ 308
Net loss	(16,196)
Ending balance at Sep. 30, 2016	$ 46,938

Statements of cash flows

Statements of cash flows - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net loss	$ (16,196)	$ (12,469)	$ (17,639)	$ (10,189)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	49	45	60	33
Share-based compensation expense	776	502	705	427
Non-cash interest expense	224	66	104	82
Accretion of debt discount	60	32	60	277
Change in fair value of warrant liability	16	(1)	52	18
Amortization and accretion on available-for-sale investments, net	17
Loss on sale of fixed assets		15	15
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(536)	(122)	(145)	54
Other assets	426	1,764	1,763	(1,154)
Accounts payable and accrued liabilities	(567)	(399)	632	1,137
Deferred revenue	(515)	500	500	200
Deferred rent	(7)	(6)	(9)	(9)
Net cash used in operating activities	(16,253)	(10,073)	(13,902)	(9,124)
Investing activities
Purchase of available-for-sale investments	(20,065)
Acquisition of property and equipment	(3)	(8)	(32)	(140)
Proceeds from the sale of fixed assets		4	4
Net cash used in investing activities	(20,068)	(4)	(28)	(140)
Financing activities
Proceeds from initial public offering, net of issuance costs	51,377
Proceeds from issuance of long-term debt	7,867	5,981	5,976	3,000
Principal payments made on long-term debt	(6,330)			(125)
Proceeds from exercise of stock options		13	14	5
Net cash provided by financing activities	52,914	5,994	25,944	15,624
Net increase (decrease) in cash and cash equivalents	16,593	(4,083)	12,014	6,360
Cash and cash equivalents, beginning of period	20,283	8,269	8,269	1,909
Cash and cash equivalents, end of period	36,876	4,186	20,283	8,269
Supplemental schedule of noncash investing and financing activities
Conversion of convertible preferred stock to common stock	48,198			3,232
Reclassification of deferred initial public offering costs	1,597
Issuance of warrant to purchase common stock	308			1,506
Issuance of warrant to purchase Series B preferred stock		164	164
Accretion of redeemable convertible preferred stock to redemption value	883	392	525	231
Deferred initial public offering costs in accounts payable and accrued expenses	$ 16	$ 228	410	602
Interest paid			100	7
Series B Preferred Stock
Financing activities
Proceeds from issuance of Series B Preferred Stock and common stock warrants, net of issuance cost				$ 12,744
Series C Preferred Stock
Financing activities
Proceeds from issuance of Series B Preferred Stock and common stock warrants, net of issuance cost			$ 19,954

The company

The company	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The company	1. The company Clearside Biomedical, Inc. (the “Company”) is a late-stage clinical biopharmaceutical company developing first-in-class drug therapies to treat blinding diseases of the eye. The Company’s current product candidates focus on treatments for diseases affecting the retina and choroid, especially diseases associated with macular edema, and are injected into the suprachoroidal space using its proprietary SCS Microinjector. Incorporated in the State of Delaware on May 26, 2011, the Company has its corporate headquarters in Alpharetta, Georgia. The Company’s activities since inception have primarily consisted of developing product and technology rights, raising capital and performing research and development activities. The Company has no current source of revenue to sustain present activities, and does not expect to generate meaningful revenue until and unless the Company receives regulatory approval of and successfully commercializes its product candidates. The Company is subject to a number of risks and uncertainties similar to those of other life science companies at a similar stage of development, including, among others, the need to obtain adequate additional financing, successful development efforts including regulatory approval of products, compliance with government regulations, successful commercialization of potential products, protection of proprietary technology and dependence on key individuals. Liquidity On June 1, 2016, 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 IPO closed on June 7, 2016 and the Company sold 7,200,000 shares of common stock at a price to the public of $7.00 per share, for net proceeds of $45.3 million. On June 30, 2016, the underwriters of the IPO partially exercised their option to purchase additional shares, and on July 6, 2016, the Company sold 948,843 additional shares of common stock at a price to the public of $7.00 per share, for net proceeds of $6.1 million. The Company paid to the underwriters underwriting discounts and commissions of $4.0 million in connection with the IPO, including the underwriters’ exercise of their option to purchase additional shares. In addition, the Company incurred expenses of $1.6 million in connection with the IPO. Thus, the aggregate net offering proceeds to the Company, after deducting underwriting discounts and commissions and offering expenses, were $51.4 million. Prior to the IPO, the Company had funded its operations primarily through the sale of convertible preferred stock and the issuance of long-term debt, resulting in aggregate proceeds of approximately $53.9 million. Even with the completion of the IPO, the Company will continue to need to obtain additional financing to fund future operations, including completing the development and commercialization of its primary product candidates. The Company will need to expend substantial resources for research and development, including costs associated with the clinical testing of its product candidates. The Company will also need to obtain additional financing to conduct additional trials for the regulatory approval of its drug candidates if requested by regulatory bodies, and completing the development of any additional product candidates that might be acquired. If such products were to receive regulatory approval, the Company would need to prepare for the potential commercialization of its product candidates and fund the commercial launch of the products, if the Company decides to commercialize the products on its own. Moreover, the Company’s fixed expenses such as rent and other contractual commitments are substantial and are expected to increase in the future. The Company had cash, cash equivalents and short-term investments of $56.9 million as of September 30, 2016 and cumulative net cash flows used in operating activities of $49.4 million and cumulative net losses of $55.6 million through September 30, 2016. In the absence of product or other revenues, the amount, timing, nature or source of which cannot be predicted, the Company’s losses will continue as it conducts its research and development activities. Until the Company can generate a sufficient amount of revenue, the Company may finance future cash needs through public or private equity offerings, license agreements, debt financings, collaborations, strategic alliances and marketing or distribution arrangements. The Company has incurred losses and negative cash flows since inception and expects operating losses and negative cash flows to continue into the foreseeable future. However, the Company is able to control spending on development activities while still advancing clinical trials for key drug and candidates and expects that the cash on hand as of September 30, 2016 will be sufficient to fund its operations for at least the next 12 months from that date.	1. The company Clearside Biomedical, Inc. (the “Company”) is a late-stage clinical biopharmaceutical company developing first-in-class drug therapies to treat blinding diseases of the eye. The Company’s current product candidates focus on diseases affecting the retina and choroid, especially diseases associated with macular edema, and are injected into the suprachoroidal space using its proprietary SCS Microinjector. Incorporated in the State of Delaware on May 26, 2011, the Company has its corporate headquarters in Alpharetta, Georgia. The Company’s activities since inception have primarily consisted of developing product and technology rights, raising capital and performing research and development activities. The Company has no current source of revenue to sustain present activities, and does not expect to generate revenue until and unless the Company receives regulatory approval of and successfully commercialize its product candidates. The Company is subject to a number of risks and uncertainties similar to those of other life science companies at a similar stage of development, including, among others, the need to obtain adequate additional financing, successful development efforts including regulatory approval of products, compliance with government regulations, successful commercialization of potential products, protection of proprietary technology and dependence on key individuals. Liquidity The Company has funded its operations to date primarily through the sale of convertible preferred stock and the issuance of long-term debt. The Company will need to obtain additional financing to fund future operations, including completing the development and commercialization of its primary product candidates. The Company will need to expend substantial resources for research and development, including costs associated with the clinical testing of its product candidates. The Company will need to obtain additional financing to conduct additional trials for the regulatory approval of its drug candidates if requested by regulatory bodies, and completing the development of any additional product candidates that might be acquired. If such products were to receive regulatory approval, the Company would need to prepare for the potential commercialization of its product candidates and fund the commercial launch of the products, if the Company decides to commercialize the products on its own. Moreover, the Company’s fixed expenses such as rent and other contractual commitments are substantial and are expected to increase in the future. The Company has incurred losses and experienced negative operating cash flows since inception, and has cumulative net cash flows used in operating activities of $33.1 million and cumulative net losses of $39.4 million for the period from May 26, 2011 (inception) to December 31, 2015. The total future need for operating capital and research and development funding significantly exceeds the cash and cash equivalents that the Company has on its balance sheet. As a result, the Company will require additional funding in the future and may not be able to raise such additional funds. In the absence of product or other revenues, the amount, timing, nature or source of which cannot be predicted, the Company’s losses will continue as it conducts its research and development activities. Until the Company can generate a sufficient amount of revenue, the Company may finance future cash needs through public or private equity offerings, license agreements, debt financings, collaborations, strategic alliances and marketing or distribution arrangements. The incurrence of indebtedness would result in increased fixed payment obligations and could also result in restrictive covenants, such as limitations on the Company’s ability to incur additional debt, limitations on its ability to acquire, sell or license intellectual property rights and other operating restrictions that could adversely impact the ability of the Company to conduct its business. If adequate funds are not available, the Company plans to delay, reduce or eliminate research and development programs or reduce administrative expenses. The Company may seek to access the public or private capital markets whenever conditions are favorable, even if the Company does not have an immediate need for additional capital at that time. In addition, if the Company raises additional funds through collaborations, strategic alliances or marketing, distribution or licensing arrangements with third parties, the Company may have to relinquish valuable rights to its technologies, future revenue streams or product candidates or to grant licenses on terms that may not be favorable to the Company. There is no assurance that the Company will be successful in obtaining sufficient financing on acceptable terms and conditions to fund continuing operations, if at all. The failure of the Company to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the Company’s business, results of operations and financial condition. However, the Company is able to control spending on development activities while still advancing clinical trials for key drug candidates through December 31, 2016 with the cash on hand as of December 31, 2015.

Significant accounting policies

Significant accounting policies	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Significant accounting policies	2. Significant accounting policies Basis of presentation The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Unaudited interim financial information The accompanying balance sheet as of September 30, 2016, statements of operations for the nine months ended September 30, 2016 and 2015 and statements of cash flows for the nine months ended September 30, 2016 and 2015 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2016 and its results of its operations for the nine months ended September 30, 2016 and 2015 and its cash flows for the nine months ended September 30, 2016 and 2015. The financial data and other information disclosed in these notes related to the nine months ended September 30, 2016 and 2015 are unaudited. The results for the nine months ended September 30, 2016 are not indicative of results to be expected for the year ending December 31, 2016, any other interim periods or any future year or period. These unaudited financial statements should be read in conjunction with the audited financial statements and related footnotes for the year ended December 31, 2015, which are included in the Company’s prospectus dated June 1, 2016, as filed pursuant to Rule 424(b) under the Securities and Exchange Act of 1933 filed, as amended, with the SEC. Use of estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of income and expenses during the reporting periods. Significant items subject to such estimates and assumptions include the accounting for useful lives to calculate depreciation and amortization, accrued liabilities, share-based compensation expense and income tax valuation allowance. Actual results could differ from these estimates. Reverse stock split On May 11, 2016, the Company effected a 1-for-2.2 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 convertible preferred stock. Accordingly, all share and per share amounts for all periods presented in these 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. The adjustment to the conversion ratio for the Series C convertible preferred stock also included an anti-dilution adjustment based on the initial public offering price of the Company’s common stock. Research and development costs Research and development costs are charged to expense as incurred and include, but are not limited to: • employee-related expenses, including salaries, benefits, travel and share-based compensation expense for research and development personnel; • expenses incurred under agreements with contract research organizations, contract manufacturing organizations and consultants that conduct clinical and preclinical studies; • costs associated with preclinical and development activities; • costs associated with technology and intellectual property licenses; • costs for the Company’s research and development facility; and • depreciation expense for assets used in research and development activities. Costs for certain development activities, such as clinical studies, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the patterns of costs incurred, and are reflected in the financial statements as prepaid or accrued expense, which are reported in accounts payable. No material adjustments to these estimates have been recorded in these financial statements. Share-based compensation Compensation cost related to share-based awards granted to employees is measured at grant date, based on the estimated fair value of the award. The Company estimates the fair value of stock options using a Black-Scholes option pricing model. Compensation expense for options granted to non-employees is determined as the fair value of consideration received or the fair value of the equity instruments issued, whichever is more reliably measured. The fair value of restricted stock awards is determined based on the fair value of the Company’s common stock on the date of grant. Share-based compensation costs are expensed on a straight-line basis (net of estimated forfeitures) over the relevant vesting period. The fair value of awards granted to non-employees is re-measured each period until the related service is complete. All share-based compensation costs are recorded in general and administrative or research and development costs in the statements of operations based upon the underlying employees’ roles within the Company. Cash equivalents Cash equivalents consist of short-term, highly liquid investments with an original term of three months or less at the date of purchase. Short-term investments Short-term investments are investments with original maturities of between 90 and 365 days when purchased and are comprised of corporate and government bonds and government agency securities. The Company classifies its short-term investments as available-for-sale securities. Short-term investments are recorded at fair value and unrealized gains and losses are recorded within accumulated other comprehensive income (loss) until realized. In addition, the Company evaluates the short-investments with unrealized losses to determine whether such losses are other-than-temporary. Concentration of credit risk arising from cash deposits in excess of insured limits The Company maintains its cash in bank deposits that at times may exceed federally insured limits. The Company has not experienced any loss in such accounts. The Company believes it is not exposed to any significant risks with respect to its cash balances. Recent accounting pronouncements In August 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-15, Statement of Cash Flows Classification of Certain Cash Receipts and Cash Payments In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718). In February 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842), In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements-Going Concern (Subtopic 205-40): Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers	2. Significant accounting policies Basis of presentation The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Use of estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of income and expenses during the reporting periods. Significant items subject to such estimates and assumptions include the accounting for useful lives to calculate depreciation and amortization, accrued liabilities, share-based compensation expense and income tax valuation allowance. Actual results could differ from these estimates. Segment information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment. All operations are located in the United States. Property and equipment, net Property and equipment is recorded at historical cost. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets. Repairs and maintenance are expensed when incurred. Upon retirement or sale, the cost of the assets disposed of and the related accumulated depreciation are removed from the accounts, and any resulting gain or loss is included in the determination of net income. Cash equivalents Cash equivalents consist of short-term, highly liquid investments with an original term of three months or less at the date of purchase. Concentration of credit risk arising from cash deposits in excess of insured limits The Company maintains its cash in bank deposits that at times may exceed federally insured limits. The Company has not experienced any loss in such accounts. The Company believes it is not exposed to any significant risks with respect to its cash balances. Deferred offering costs The Company capitalizes certain legal, accounting and other third-party fees that are directly associated with in-process equity financings as other assets until such financings are consummated. After consummation of the equity financing, these costs are recorded in stockholders’ equity (deficit) as a reduction of additional paid-in capital generated as a result of the offering or as a reduction to the carrying value of preferred stock issued, if such stock is classified outside of stockholders’ equity (deficit). Should the equity financing no longer be considered probable of being consummated, the deferred offering costs would be expensed immediately as a charge to operating expenses in the statement of operations. As of December 31, 2014, the Company had recorded $1.8 million of deferred offering costs. In September 2015, $1.9 million of deferred offering costs were charged to operating expenses due to the postponement of the equity financing. As of December 31, 2015, the Company had recorded $0.4 million of deferred offering costs in connection with a new equity financing. Research and development costs Research and development costs are charged to expense as incurred and include, but are not limited to: • employee-related expenses, including salaries, benefits, travel and share-based compensation expense for research and development personnel; • expenses incurred under agreements with contract research organizations, contract manufacturing organizations and consultants that conduct clinical and preclinical studies; • costs associated with preclinical and development activities; • costs associated with technology and intellectual property licenses; • costs for the Company’s research and development facility; and • depreciation expense for assets used in research and development activities. Costs for certain development activities, such as clinical studies, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the patterns of costs incurred, and are reflected in the financial statements as prepaid or accrued expense, which are reported in accounts payable. No material adjustments to these estimates have been recorded in these financial statements. Share-based compensation Compensation cost related to share-based awards granted to employees is measured at grant date, based on the estimated fair value of the award. The Company estimates the fair value of stock options using a Black-Scholes option pricing model. Compensation expense for options granted to non-employees is determined as the fair value of consideration received or the fair value of the equity instruments issued, whichever is more reliably measured. The fair value of restricted stock awards is determined based on the fair value of the Company’s common stock on the date of grant. Share-based compensation costs are expensed on a straight-line basis (net of estimated forfeitures) over the relevant vesting period. The fair value of awards granted to non-employees is re-measured each period until the related service is complete. All share-based compensation costs are recorded in general and administrative or research and development costs in the statements of operations based upon the underlying employees’ roles within the Company. Debt discount The Company follows the authoritative guidance in Accounting Standards Codification (“ASC”) 470-20-25-2, Debt with Conversion of Other Options Fair value measurements The Company records certain financial assets and liabilities at fair value in accordance with the provisions of ASC Topic 820, Fair Value Measurements and Disclosures Stock purchase warrants The Company accounts for stock purchase warrants as liabilities based upon the characteristics and provisions of the underlying instruments. These liabilities are recorded at their fair value on the date of issuance within other non-current liabilities on the balance sheet and are remeasured on each subsequent reporting date, with fair value changes recognized as income (decreases in fair value) or expenses (increases in fair value) in other income (expense), net in the statements of operations. The fair value of these liabilities is estimated using the Black-Scholes method. Income taxes Deferred tax assets or liabilities are recorded for temporary differences between financial statement and tax basis of assets and liabilities, using enacted rates in effect for the year in which the differences are expected to reverse. A valuation allowance is recorded if it is more likely than not that a deferred tax asset will not be realized. The Company has provided a full valuation allowance on its deferred tax assets, which primarily consist of cumulative net operating losses of $14.2 million for the period from May 26, 2011 (inception) to December 31, 2015. Due to its history of operating losses since inception and losses expected to be incurred in the foreseeable future, a full valuation allowance was considered necessary. Recent accounting pronouncements In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-09, Compensation-Stock Compensation (Topic 718) In February 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842), In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern, Net loss per share of common stock Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period, without consideration of the dilutive effect of potential common stock equivalents. Diluted net loss per share gives effect to all dilutive potential shares of common stock outstanding during this period. For all periods presented, the Company’s potential common stock equivalents, which include convertible preferred stock, stock options, unvested restricted stock and stock purchase warrants, have been excluded from the computation of diluted net loss per share as their inclusion would have the effect of reducing the net loss per share. Therefore, the denominator used to calculate both basic and diluted net loss per share is the same in all periods presented. The Company’s potential common stock equivalents that have been excluded from the computation of diluted net loss per share for all periods presented because of their antidilutive effect consisted of the following: Year Ended December 31, 2014 2015 Convertible preferred stock 7,074,961 9,472,530 Outstanding stock options 1,098,486 1,261,637 Unvested restricted stock 20,688 6,485 Stock purchase warrants 900,724 146,298 9,094,859 10,886,950

Net loss per share

Net loss per share	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Net loss per share	15. Net loss per share Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period, without consideration of the dilutive effect of potential common stock equivalents. Diluted net loss per share gives effect to all dilutive potential shares of common stock outstanding during this period. For all periods presented, the Company’s potential common stock equivalents, which include convertible preferred stock, stock options, unvested restricted stock and stock purchase warrants, have been excluded from the computation of diluted net loss per share as their inclusion would have the effect of reducing the net loss per share. Therefore, the denominator used to calculate both basic and diluted net loss per share is the same in all periods presented. The Company’s potential common stock equivalents that have been excluded from the computation of diluted net loss per share for all periods presented because of their antidilutive effect consisted of the following: Nine Months Ended September 30, 2016 2015 Convertible preferred stock — 7,074,961 Outstanding stock options 1,414,594 1,030,025 Unvested restricted stock — 10,030 Stock purchase warrants 55,770 146,298 1,470,364 8,261,314	Net loss per share of common stock Basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period, without consideration of the dilutive effect of potential common stock equivalents. Diluted net loss per share gives effect to all dilutive potential shares of common stock outstanding during this period. For all periods presented, the Company’s potential common stock equivalents, which include convertible preferred stock, stock options, unvested restricted stock and stock purchase warrants, have been excluded from the computation of diluted net loss per share as their inclusion would have the effect of reducing the net loss per share. Therefore, the denominator used to calculate both basic and diluted net loss per share is the same in all periods presented. The Company’s potential common stock equivalents that have been excluded from the computation of diluted net loss per share for all periods presented because of their antidilutive effect consisted of the following: Year Ended December 31, 2014 2015 Convertible preferred stock 7,074,961 9,472,530 Outstanding stock options 1,098,486 1,261,637 Unvested restricted stock 20,688 6,485 Stock purchase warrants 900,724 146,298 9,094,859 10,886,950

Property and equipment, net

Property and equipment, net	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Property and equipment, net	3. Property and equipment, net Property and equipment, net consisted of the following (dollar amounts in thousands): Estimated Useful Lives (Years) September 30, 2016 December 31, 2015 Furniture and fixtures 5 $ 69 $ 66 Machinery and equipment 5 121 121 Computer equipment 3 27 27 Leasehold improvements Lesser of Useful life or remaining lease term 45 45 262 259 Less: Accumulated depreciation (152 ) (103 ) $ 110 $ 156	3. Property and equipment, net Property and equipment, net consisted of the following (dollar amounts in thousands): Estimated Useful Lives (Years) December 31, 2014 2015 Furniture and fixtures 5 $ 95 $ 66 Machinery and equipment 5 105 121 Computer equipment 3 27 27 Leasehold improvements Lesser of useful life or remaining lease term 33 45 260 259 Less: Accumulated depreciation (55 ) (103 ) $ 205 $ 156

Accrued liabilities

Accrued liabilities	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Accrued liabilities	4. Accrued liabilities Accrued liabilities consisted of the following (in thousands): September 30, 2016 December 31, 2015 Accrued research and development $ 790 $ 569 Accrued bonuses 478 530 Accrued professional fees 78 668 Accrued vacation 88 64 Accrued interest payable 5 15 Accrued expense 117 139 $ 1,556 $ 1,985	4. Accrued liabilities Accrued liabilities consisted of the following (in thousands): December 31, 2014 2015 Accrued research and development $ 427 $ 569 Accrued bonuses 279 530 Accrued professional fees 178 668 Accrued vacation 53 64 Accrued interest payable — 15 Accrued expense 220 139 $ 1,157 $ 1,985

Long-term debt

Long-term debt	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
Long-term debt	5. Long-term debt Loan and security agreements In September 2016, the Company entered into an amended and restated loan and security agreement (the “loan agreement”) with Silicon Valley Bank (“SVB”), MidCap Funding XII Trust and MidCap Financial Trust (together, “MidCap” and collectively with SVB, the “Lenders”), which amended and restated in its entirety the Company’s prior loan and security agreement with SVB dated as of April 14, 2015 (the “original loan agreement”), under which the Company had borrowed $6.0 million in April and May 2015. The loan agreement provides for new term loans of up to $15.0 million, with a floating interest rate equal to 7% plus the greater of (i) the 30-day U.S. LIBOR, reported in the Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue, or (ii) 0.50%. The interest rate on the original loan agreement was equal to the lender’s prime rate less 0.50 percent. Under the terms of the new loan, an initial tranche of $8.0 million was advanced on September 28, 2016. The remaining $7.0 million will become available beginning on the later of (i) September 30, 2017 and (ii) the date on which the Lenders have received evidence, in form and substance reasonably satisfactory to them, that the Company has produced clinical trial data sufficient to file a New Drug Application, or NDA, for its drug candidate CLS-1001 for the treatment of uveitis. Once the draw period for the remaining $7.0 million has commenced, the Company may draw funds at its discretion until the earlier of (i) December 31, 2017 and (ii) the occurrence of an event of default under the loan agreement. The Company is required to pay accrued interest only through December 31, 2017 on the outstanding amount, followed by 30 equal payments of principal and accrued interest. The Company has the option to prepay the outstanding balance of the term loans in full, subject to a prepayment fee of (i) 3% of the original principal amount of the aggregate term loans for any prepayment prior to September 28, 2017 or (ii) 2% of the original principal amount of the aggregate term loans for any prepayment between September 28, 2017 and May 31, 2020. A final payment of $0.5 million, or 6.50% of the aggregate borrowed amount, is due at maturity of the loan on June 1, 2020, or upon the prepayment of the facility or the acceleration of amounts due under the facility as a result of an event of default, and is being accreted in long-term debt over the life of the loan. Of the initial $8.0 million advanced on September 28, 2016, $5.3 million was used to repay all amounts outstanding under the original loan agreement. Closing costs incurred in the refinancing portion of the loan were recorded as expense while the financing costs for the new portion of the loan are recorded in long-term debt and being accreted over the life of the loan. Upon repayment of the original loan agreement, all remaining closing costs associated with the original loan agreement are being accreted to long-term debt over the life of the new loan. The term loans under the loan agreement are secured by substantially all of the Company’s assets, except that the collateral does not include any of the Company’s intellectual property. However, pursuant to the terms of a negative pledge arrangement, the Company has agreed not to encumber any of its intellectual property. Interest expense on the borrowings under the original loan agreement was $129,000 and $72,000 for the nine months ended September 30, 2016 and 2015, respectively. Accretion of the scheduled final payment was $224,000 and $64,000 for the nine months ended September 30, 2016 and 2015, respectively. Accretion of the deferred closing costs was $7,000 and $5,000 for the nine months ended September 30, 2016 and 2015, respectively. As of September 30, 2016, the scheduled payments for the loan agreement, including the scheduled final payment in 2020, were as follows (in thousands): Year Ending December 31, Principal Interest and Final Payment Total 2016 $ — $ 158 $ 158 2017 — 608 608 2018 3,200 476 3,676 2019 3,200 234 3,434 2020 1,600 545 2,145 $ 8,000 $ 2,021 $ 10,021	5. Long-term debt Note purchase agreement In December 2012, the Company entered into a $150,000 unsecured note purchase agreement with a lender and borrowed $150,000 on that date. Amounts borrowed under the agreement bore interest at 5% per annum. All unpaid principal, together with the balance of unpaid and accrued interest, were due and payable on demand at any time after the earlier of (i) the maturity date of December 2017, (ii) the date on which the Company has achieved sustainable profitability for a period of at least two consecutive fiscal years in accordance with generally accepted accounting principles, (iii) without the prior written consent of the lender, the date on which an equity financing of the Company in which the Company issues shares of common stock, preferred stock or other equity interests in the Company in a transaction or series of related transactions and receives an investment of cash in consideration of such issuance in the amount of not less than $7.0 million or consolidation of the Company or the sale or transfer by the Company’s stockholders of capital stock of the Company representing more than 50% of the voting power occurs or (iv) upon or after the occurrence of an event of default. The repayment acceleration provision specifically excluded the Series A-1 Preferred Stock financing that occurred in January 2013. The unsecured promissory note converted into 60,291 shares of Series B convertible preferred stock in connection with the Company’s August 2014 Series B convertible preferred stock financing. Interest expense on the borrowings under the note purchase agreement was $5,000 and $0 for the years ended December 31, 2014 and 2015, respectively. As of December 31, 2014 and 2015, the total amount of borrowings due under this note purchase agreement was $0. Loan agreements In April 2013, the Company borrowed $125,000 under a loan agreement, which borrowings bore interest at a compounded annual rate of 4.25%. As of December 31, 2013, the total amount of borrowings due under the loan agreement was $125,000. All unpaid principal, together with the balance of unpaid and accrued interest, was due and payable on demand at any time after the earlier of (i) the maturity date of February 2016, (ii) the date on which the Company sells, leases, transfers or otherwise disposes of all or substantially all of its assets now owned or hereafter acquired, (iii) the date on which the Company makes a public offering of the Company’s capital stock or equity interests, (iv) the date on which the Company takes any action which would result in a change in the direct or indirect control of 50% or more of the capital stock or equity interest ownership of the Company, (v) the date after December 31, 2013 on which the Company had received additional equity investments or milestone payments or license fees totaling $2.5 million in the aggregate over any 12-month period or (vi) upon or after the occurrence of an event of default. In May 2014, the Company repaid this loan in full. Interest expense on the borrowings under the loan agreement was $2,000 and $0 for the years ended December 31, 2014 and 2015, respectively. As of December 31, 2013, the Company had recorded unamortized debt discount of $7,000, relating to the detachable warrants issued in conjunction with the loan agreement (Note 10). Debt discounts are amortized using the effective interest method through the earlier of the date of maturity or the conversion of the debt. As of December 31, 2013, cumulative amortization of debt discount amounted to $3,000. The remaining debt discount was written off to interest expense during 2014 when the loan was repaid. In April 2015, the Company entered into a loan agreement with a bank for borrowings up to $6.0 million, with a floating interest rate equal to the Wall Street Journal’s prime rate minus 0.50 percent. Under the terms of the loan, an initial tranche of $4.0 million was advanced on April 15, 2015 and an additional tranche of $2.0 million was advanced on May 15, 2015. The Company is required to pay accrued interest only for a period of 12 months from the date of each advance, followed by 30 equal monthly payments of principal and accrued interest. A final payment of $0.3 million, or 5.50% of the aggregate borrowed amount, is due at maturity of the loan in 2018 and is being accreted in long-term debt over the life of the loan. Closing costs of $24,000 were recorded in long-term debt and are also being accreted over the life of the loan. Interest expense on the borrowings under the loan agreement was $0.1 million for the year ended December 31, 2015. Accretion of the scheduled final payment was $0.1 million for the year ended December 31, 2015. Accretion of the deferred closing costs was $7,400 for the year ended December 31, 2015. As of December 31, 2015, the annual payments for the loan agreement, including the scheduled final payment in 2018, were as follows (in thousands): Year Ending December 31, Principal Interest and Final Payment Total 2016 $ 1,733 $ 166 $ 1,899 2017 2,400 96 2,496 2018 1,867 354 2,221 $ 6,000 $ 616 $ 6,616

Convertible shareholder notes p

Convertible shareholder notes payable	12 Months Ended
	Dec. 31, 2015
Text Block [Abstract]
Convertible shareholder notes payable	6. Convertible shareholder notes payable In April 2014, the Company authorized the sale of convertible promissory notes (the “Bridge Notes”) to its existing stockholders, including two of its executive officers and one of its directors in their individual capacities, in the aggregate principal amount of $6.0 million. In April 2014, the Company issued $3.0 million in aggregate principal amount of Bridge Notes. The outstanding notes accrued interest at a rate of 7%, with principal plus interest due upon maturity in April 2015, unless earlier converted. The Bridge Notes were convertible upon the occurrence of a qualified financing. The Company’s August 2014 Series B convertible preferred stock financing was a qualified financing as contemplated by the Bridge Notes, and accordingly the principal and interest under all of the Bridge Notes was converted automatically into an aggregate of 1,137,652 shares of Series B convertible preferred stock in connection with this financing. In connection with the issuance of the Bridge Notes, the Company also issued warrants to the lenders to purchase an aggregate of 112,802 shares of common stock at an exercise price of $0.02 per share. Unless earlier exercised, these warrants will expire upon the closing of an initial public offering. Interest expense on the borrowings under the Bridge Notes was $69,000 for the year ended December 31, 2014.

Income taxes

Income taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income taxes	7. Income taxes No provision for U.S. federal or state income taxes has been recorded as the Company has incurred net operating losses since inception. Significant components of the Company’s net deferred income tax assets consist of the following (in thousands): December 31, 2014 2015 Current Deferred tax asset (liability) Non-deductible accrued expenses $ 20 $ 230 Deferred rent 4 3 Valuation allowance (24 ) (233 ) Net current deferred tax asset $ — $ — Non-current Deferred tax asset (liability) Stock compensation expense $ 70 $ 88 Net operating loss carryforwards 7,891 14,169 Depreciation differences (31 ) (28 ) Federal tax credits 447 850 State tax credits 196 262 Deferred revenue — 77 Deferred rent 4 1 Charitable contributions 3 3 Valuation allowance (8,580 ) (15,422 ) Net non-current deferred tax asset $ — $ — A reconciliation of the statutory tax rates and the effective tax rates is as follows: Year Ended December 31, 2014 2015 U.S. federal tax rate 34.00% 34.00% State tax rate 4.41 4.54 Permanent difference and other (1.15 ) (1.26 ) Tax credit 4.54 2.66 Valuation allowance (41.79 ) (39.94 ) 0.00% 0.00% Realization of the future tax benefits is dependent on the Company’s ability to generate sufficient taxable income within the carryforward period. Due to the Company’s history of operating losses, the deferred tax assets arising from the aforementioned future tax benefits are currently not likely to be realized and, accordingly, are offset by a full valuation allowance. The income tax provision varies from the expected provision determined by applying the federal statutory income tax rate to income (loss). The reasons for the difference in the expected provision, as determined by applying the federal statutory income tax rate to net income (loss) is primarily due to the increase in the deferred income tax valuation allowance of $4.2 million and $7.0 million for the years ended December 31, 2014 and 2015, respectively. As of December 31, 2015, the Company had net deferred tax assets primarily related to net operating loss carryforwards of $14.2 million, which expire through 2035. 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 the Internal Revenue Code of 1986, as amended, and similar state provisions. The effect of an ownership change could be an imposition of an annual limitation on the use of net operating loss carryforwards attributable to periods before the change. The U.S. federal statute of limitations remains open for the periods from inception and forward. The Company has not been the subject of examination by the taxing authorities. The Company has no uncertain tax positions.

Convertible debt

Convertible debt	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Text Block [Abstract]
Convertible debt	6. Convertible debt As of December 31, 2015, the Company had authorized an aggregate of 20,913,331 shares of Series A, A-1, B and C convertible preferred stock, par value $0.001 per share. Upon the closing of the Company’s IPO on June 1, 2016, all 20,839,633 shares of the Company’s convertible preferred stock that were issued and outstanding on that date were automatically converted into an aggregate of 9,614,159 shares of its common stock. As of September 30, 2016, there were 10,000,000 shares of preferred stock authorized, none of which were issued and outstanding.	8. Convertible preferred stock The Company has authorized 20,913,331 shares of preferred stock. Of the authorized shares of preferred stock, 5,198,826 shares have been designated as Series A Convertible Preferred Stock (“Series A”), 4,373,481 shares have been designated as Series A-1 Preferred Stock (“Series A-1”), 6,066,345 shares have been designated as Series B Preferred Stock (“Series B”) and 5,274,679 shares have been designated as Series C Preferred Stock (“Series C”). The Series A, Series A-1, Series B and Series C shares were issued at a price of $0.78589, $1.81320, $2.69783 and $3.79170 per share, respectively. The following table summarizes the activity of convertible preferred stock (dollar amounts in thousands, except per share amounts): Series A Preferred Stock Series A-1 Preferred Stock Series B Preferred Stock Series C Preferred Stock Total Convertible Preferred Stock Shares Amount Shares Amount Shares Amount Shares Amount Balance at January 1, 2014 5,198,826 $ 4,040 4,356,931 $ 7,831 — $ — — $ — $ 11,871 Issuance of Series B at $2.69783 per share on August 29, 2014, net of issuance cost of $236 — — — — 4,811,259 11,501 — — 11,501 Conversion of promissory notes and interest payable at $2.69783 per share on August 29, 2014 — — — — 1,197,943 3,232 — — 3,232 Accretion of stock issuance costs — 46 — 27 — 158 — — 231 Balance at December 31, 2014 5,198,826 4,086 4,356,931 7,858 6,009,202 14,891 — — 26,835 Issuance of Series C at $3.7917 per share in November and December 2015, net of issuance cost of $46 — — — — — — 5,274,674 19,954 19,954 Accretion of stock issuance costs — — — 42 — 481 — 2 525 Balance at December 31, 2015 5,198,826 $ 4,086 4,356,931 $ 7,900 6,009,202 $ 15,372 5,274,674 $ 19,956 $ 47,314 Dividends Holders of Series A, Series A-1, Series B and Series C shares, in preference of common stockholders, shall be entitled to receive (a) when, as and if declared by the board of directors (the “Board”), but only out of funds that are legally available therefore, or (b) upon the liquidation, dissolution or winding up of the Company, whether voluntary or involuntary, cumulative cash dividends at the rate of 8% per annum of the applicable original issuance price of such series of preferred stock. The total cumulative preferred dividends in arrears, if declared, for the preferred stock as of December 31, 2014 and 2015 were $2.5 million and $5.0 million, respectively. Liquidation Upon a liquidation event (as defined in the amended and restated certificate of incorporation) the Series A, Series A-1, Series B and Series C holders will be paid their liquidation preference of $0.78589, $1.81320, $2.69783 and $3.79170 per share, respectively, which is the original issue price plus any accrued and declared but unpaid dividends on such class of capital stock. If the net assets of the Company are insufficient to cover the liquidation preference, the Company will distribute the available funds among the holders of Series A, Series A-1, Conversion Each share of Series A, Series A-1, Series B and Series C is convertible into a number of fully paid shares of common stock at any time at the option of the stockholder. The Series A, Series A-1, Series B and Series C shares may be converted into common stock at a conversion price per share of $1.72896, $3.98904, $5.93523, and $8.34174, respectively. In addition, the Series A, Series A-1, Series B and Series C shares are convertible into common stock immediately upon: (i) the closing of an initial public offering generating net proceeds of not less than $50.0 million to the Company, at a price per share of at least $12.51261; or (ii) the written consent of the holders of at least a majority of the outstanding shares of preferred stock and the holders of at least 50% of the outstanding shares of Series C convertible preferred stock. As described in the amended and restated certificate of incorporation, a reduction in the conversion price will occur if the Company sells common stock for less than the conversion price of the Series A, Series A-1, Series B and Series C shares. Based on the conversion terms, there were no beneficial conversion features associated with Series A, Series A-1, Series B and Series C shares. In addition, the potential reduction in the conversion price did not result in the conversion price feature meeting the definition of a derivative, which would require separate accounting. Voting Each holder of the Series A, Series A-1, Series B and Series C shares shall be entitled to the number of votes equal to the number of shares of common stock into which such shares of Series A, Series A-1, Series B and Series C may be converted, and shall have voting rights and powers equal to the voting rights and powers of the common stock, with certain limitations. Redemption Series A, Series A-1, Series B and Series C will be subject to redemption at the option of the investors holding a majority of the Series A, Series A-1, Series B and Series C shares at any time after the sixth anniversary of the issuance in an amount equal to the liquidation preference. On such redemption date, the Company shall redeem, on a pro rata basis in accordance with the number of shares of Series A, Series A-1, Series B and Series C owned by each holder, that number of outstanding shares of Series A, Series A-1, Series B and Series C determined by dividing (i) the total number of shares of Series A, Series A-1, Series B and Series C outstanding immediately prior to such redemption date by (ii) the number of remaining redemption dates including the redemption date to which such calculation applies. If the Company does not have sufficient funds legally available to redeem on any redemption date all Series A, Series A-1, Series B and Series C shares to be redeemed on such redemption date, the Company shall redeem a pro rata portion of each holder’s Series A, Series A-1, Series B and Series C shares out of funds legally available therefor, based on the respective amounts which would otherwise be payable in respect of the shares to be redeemed if the legally available funds were sufficient to redeem all such shares, and shall redeem the remaining shares to have been redeemed as soon as practicable after the Company has funds legally available therefor.

Common stock

Common stock	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Equity [Abstract]
Common stock	7. Common stock The Company’s amended and restated certificate of incorporation authorizes the Company to issue 100,000,000 shares of $0.001 par value common stock. As of September 30, 2016 and December 31, 2015, there were 20,545,752 and 2,659,262 shares of common stock outstanding, respectively, which excluded 6,478 shares of unvested restricted stock at December 31, 2015. There was no unvested restricted stock as of September 30, 2016.	9. Common stock The Company’s amended and restated certificate of incorporation authorizes the Company to issue 40,000,000 shares of $0.001 par value common stock. As of December 31, 2014 and 2015, there were 1,816,467 and 2,659,262 shares of common stock outstanding, respectively, which excluded 20,688 and 6,485 shares, respectively, of unvested restricted stock. The terms, rights, preferences and privileges of the Company’s common stock are as follows: Voting Each holder of common stock is entitled to one vote for each share of common stock held on all matters submitted to a vote of the stockholders, including the election of directors. The Company’s amended and restated certificate of incorporation and bylaws do not provide for cumulative voting rights. Dividends Subject to preferences that may be attributable to any then outstanding convertible preferred stock, the holders of the Company’s outstanding shares of common stock are entitled to receive dividends, if any, as may be declared by the Company’s board of directors out of legally available funds. Liquidation In the event of the Company’s liquidation, dissolution or winding up, holders of common stock will be entitled to share ratably in the net assets legally available for distribution to stockholders after the payment of all the Company’s debts and other liabilities, subject to satisfaction of the liquidation preferences granted to the holders of any outstanding preferred stock. Rights and preference Holders of the Company’s common stock have no preemptive, conversion or subscription rights, and there are no redemption or other related provisions attributable to the common stock. The rights, preferences and privileges of the holders of common stock are subject to, and may be adversely affected by, the rights of the holders of shares of any series of preferred stock of the Company that may be issued.

Stock purchase warrants

Stock purchase warrants	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Text Block [Abstract]
Stock purchase warrants	8. Stock purchase warrants Preferred stock warrants During 2013, in connection with a loan agreement, the Company issued a warrant to the lender to purchase up to 16,550 shares of Series A-1 preferred stock at a price per share of $1.8132. The term of the warrant extended until 10 years from the grant date and the warrant was exercisable at any time during that 10-year period. This warrant was outstanding at December 31, 2015 and had a weighted average remaining life of 6.8 years and a fair value of $58,000. The warrant was automatically converted to a common stock warrant and was net exercised on June 6, 2016, resulting in the issuance of 3,236 shares of common stock. In April 2015, in connection with another loan agreement, the Company issued a warrant to the lenders to purchase up to 57,143 shares of Series B preferred stock at a price per share of $3.50. The term of the warrant extends until 10 years from the grant date and the warrant is exercisable at any time during that 10-year period. The warrant was automatically converted into a warrant to purchase 25,974 shares of common stock at an exercise price of $7.70 upon the closing of the IPO. This warrant was outstanding at September 30, 2016 and December 31, 2015 and had a weighted average remaining life of 8.5 and 9.25 years, respectively. The fair value of the warrant was $0.3 million and $0.2 million at September 30, 2016 and December 31, 2015, respectively. Common stock warrants During 2014, in connection with the sale of convertible promissory notes in connection with a preferred stock financing, the Company issued warrants to the lenders to purchase up to an aggregate of 112,802 shares of common stock at a price per share of $0.02. These warrants were outstanding at December 31, 2015 and had a remaining life of 8.2 years. These warrants, which would have otherwise expired upon the closing of the IPO, were automatically net exercised for an aggregate of 112,441 shares of common stock upon the closing of the IPO. In September 2016, in connection with the amended and restated loan and security agreement, the Company issued warrants to the lenders to purchase up to 29,796 shares of common stock at a price per share of $10.74. The warrants expire in September 2026, or earlier upon the occurrence of specified mergers or acquisitions of the Company, and are immediately exercisable. The warrants were recorded in equity and have a weighted average remaining life of 10 years and a fair value of $0.3 million at September 30, 2016.	10. Stock purchase warrants During 2013, in connection with the loan agreement (Note 5), the Company issued a warrant to the lender to purchase up to 16,550 shares of Series A-1 preferred stock at a price per share of $1.8132. The term of the warrant extends until 10 years from the grant date and the warrant is exercisable at any time during that 10-year The Company estimated the fair value of the warrants at issuance using the Black-Scholes option-pricing model utilizing the fair value of the underlying preferred stock. The estimates in the Black-Scholes option pricing model are based, in part, on assumptions, including but not limited to the volatility of comparable public companies, the expected life of the warrants, the risk-free interest rate and the fair value of the equity underlying the warrants. Key assumptions utilized in the fair value calculation for the warrants appear in the table below: December 31, 2014 2015 Expected term (years) 5.00 5.00 Volatility 109.60% 113.50% Risk-free interest rate 2.10% 2.13% Dividend yield 0.00% 0.00% The fair value of the Series A-1 warrant was $42,000 and $58,000 at December 31, 2014 and 2015, respectively. During 2014, in connection with the issuance of the Bridge Notes (Note 6), the Company issued warrants to the lenders to purchase up to 112,802 shares of common stock at a price per share of $0.02. These warrants were outstanding at December 31, 2014 and December 31, 2015 and had a remaining life of 9.2 and 8.2 years, respectively. If unexercised, these warrants will expire upon the closing of an initial public offering. In connection with its Series B convertible preferred stock financing in August 2014, the Company issued warrants to purchase an aggregate of 780,400 shares of common stock at an exercise price of $0.02 per share. These warrants were exercised on May 20, 2015. At the date of issuance, the total value of the common stock warrants issued in connection with the Series B financing was estimated to be $1.2 million. In order to determine the fair value of these common warrants, the Company used a hybrid of an option pricing model and a probability-weighted expected return method (“PWERM”). The estimates in the option pricing model were based, in part, on assumptions, including but not limited to the volatility of comparable public companies, the expected life of the warrants, the risk-free interest rate and the fair value of the equity underlying the warrants. Significant inputs for the PWERM included an estimate of the Company’s equity value and an estimated probability and timing for each valuation scenario. The Company attributed a 60% weighting to option pricing model, a 24% weighting to an early 2015 IPO scenario within the PWERM and a 16% weighting to a late 2015 IPO scenario within the PWERM. In April 2015, in connection with the loan agreement, the Company issued a warrant to the lenders to purchase up to 57,143 shares of Series B preferred stock at a price per share of $3.50. The term of the warrant extends until 10 years from the grant date and the warrant is exercisable at any time during that 10-year period. This warrant was outstanding at December 31, 2015 and had a weighted average remaining life of 9.25 years. The Company estimated the fair value of the Series B preferred warrants under three scenarios, the option price modeling, for which the Company took the value from the model discounted for the lack of marketability, and two IPO scenarios, early and late. Under the IPO scenarios, the Company calculated the value of the warrant based on a call option of the common share at IPO (assuming the Series B preferred stock would convert to common stock) given the time to exit and the term of the warrants stipulated in the contract. The Company then applied a discount for lack of marketability. The Company also ran the valuation for the Series B preferred warrants at the issue date of April 15, 2015 based on the model, financials, and capitalization table as of March 31, 2015, assuming there had been no material changes to the business over the 15-day period since the March 31, 2015 valuation. The Company utilized the same methodology to calculate the value of the warrants as of December 31, 2015. The fair value of the Series B preferred warrant was $200,000 at December 31, 2015.

Share-based compensation

Share-based compensation	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-based compensation	9. Share-based compensation In January 2016, the Company’s board of directors adopted and approved the Clearside Biomedical, Inc. 2016 Equity Incentive Plan (the “2016 Plan”) which became effective in connection with the IPO on June 1, 2016. The 2016 Plan provides for the grant of share-based awards to employees, directors and consultants of the Company. The Company has reserved 1,818,182 shares of common stock for issuance under the 2016 Plan. The 2016 Plan provides for the grant of incentive stock options to employees, and for the grant of nonqualified stock options, restricted stock awards, restricted stock unit awards, stock appreciation rights, performance stock awards and other forms of stock compensation to the Company’s employees, directors, and non-employee third parties. The number of shares of common stock reserved for issuance under the 2016 Plan will automatically increase on January 1 each year, for a period of ten years, from January 1, 2017 through January 1, 2026, by 4% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s board of directors. At September 30, 2016, under the 2016 Plan, options to purchase 157,500 shares of the Company’s common stock were outstanding at a weighted average price of $6.64 per share and 1,660,682 shares remained available for future grant. As a result of the adoption of the 2016 Plan, no further grants may be made under the Company’s 2011 Stock Incentive Plan (the “2011 Plan”). The 2011 Plan provided for the grant of share-based awards to employees, directors and consultants of the Company. At September 30, 2016, options to purchase 1,239,858 shares of the Company’s common stock were outstanding under the 2011 Plan at a weighted average exercise price of $2.35 per share. Share-based compensation is accounted for in accordance with the provisions of ASC 718, Compensation-Stock Compensation The Company has granted stock option awards to employees, directors and consultants. Share-based compensation expense for options granted is reflected in the statements of operations as follows (in thousands): Nine Months Ended September 30, 2016 2015 Research and development $ 375 $ 229 General and administrative 401 273 Total $ 776 $ 502 The following table summarizes the activity related to stock options during the nine months ended September 30, 2016: Number of Shares Weighted Average Exercise Price Options outstanding at January 1, 2016 1,261,638 $ 2.41 Granted 174,736 6.79 Exercised (1,326 ) 0.40 Cancelled/Forfeited (20,454 ) 6.03 Options outstanding at September 30, 2016 1,414,594 2.90 Options exercisable at December 31, 2015 500,797 0.92 Options exercisable at September 30, 2016 686,439 1.22 As of September 30, 2016, the Company had $3.1 million of unrecognized compensation expense related to unvested stock options, which is expected to be recognized over a weighted average period of 1.5 years.	11. Share-based compensation In November 2011, the Company’s Board adopted and approved the Clearside Biomedical, Inc. 2011 Stock Incentive Plan (the “Plan”) which provides for the grant of share-based awards to employees, directors and consultants of the Company. The Company has reserved 1,517,625 shares of common stock for issuance under the Plan. In February 2016, the Company awarded an option grant to a newly appointed board member. This option grant was outside of the Plan. The Board shall determine price, term and vesting conditions of all share-based awards at their grant date. Absent a public market price for the Company’s common stock, the board of directors will determine the estimated fair value for the underlying common stock. Share-based awards vest over variable periods, generally from one to five years, and expire not more than ten years after the date of grant. The total share-based compensation expense recognized is reflected in the statements of operations as follows (in thousands): Year Ended December 31, 2014 2015 Research and development $ 218 $ 327 General and administrative 209 378 Total $ 427 $ 705 Share-based compensation is accounted for in accordance with the provisions of ASC 718, Compensation-Stock Compensation The following table sets forth the weighted average assumptions utilized in the fair value calculation for the underlying common stock for the years ended December 31, 2014 and 2015. Year Ended December 31, 2014 2015 Expected term (years) 7.00 7.00 Expected stock price volatility 85.64% 86.63% Risk-free interest rate 1.99% 2.09% Expected dividend yield 0.00% 0.00% Expected term (in years): Risk-free interest rate: Expected dividend yield: Expected stock price volatility: Stock options The Company has granted stock option awards to employees, directors and consultants. Share-based compensation expense for options granted is reflected in the statements of operations as follows (in thousands): Year Ended December 31, 2014 2015 Research and development $ 91 $ 327 General and administrative 192 378 Total $ 283 $ 705 The following table summarizes the activity related to stock options: Number of Shares Weighted Average Exercise Price Options outstanding at January 1, 2014 770,062 $ 0.34 Granted 376,126 3.38 Exercised (24,803 ) 0.17 Cancelled/Forfeited (22,899 ) 0.15 Options outstanding at December 31, 2014 1,098,486 1.39 Granted 289,619 5.68 Exercised (50,980 ) 0.27 Cancelled/Forfeited (75,488 ) 1.67 Options outstanding at December 31, 2015 1,261,637 2.40 The following table provides additional information about the Company’s stock options that were outstanding and exercisable at December 31, 2015 (aggregate intrinsic values in thousands): Exercise Price Options Outstanding Weighted Average Exercise Price Aggregate Intrinsic Value Average Remaining Contractual Life (Years) Options Exercisable Weighted Average Exercise Price Aggregate Intrinsic Value $0.02 11,363 5.9 11,363 0.15 72,987 6.4 67,510 0.40 544,493 7.6 329,131 3.08 31,818 8.6 11,267 3.41 311,357 9.0 79,254 5.57 232,802 9.9 — 6.16 56,817 9.5 2,272 1,261,637 $ 2.40 $ 7,210 500,797 $ 0.92 $ 3,606 As of December 31, 2015, the Company had $3.0 million of unrecognized compensation expense related to unvested stock options granted under the Plan. This cost is expected to be recognized over a weighted average period of 1.7 years as of December 31, 2015. The weighted average remaining contractual life of all outstanding options as of December 31, 2015 was 8.4 years. The intrinsic value is calculated as the difference between the estimated fair market value and the exercise price per share of the stock options. The estimated fair market value per share of common stock as of December 31, 2015 was $8.12. Restricted stock In 2011, the founders of the Company purchased restricted common stock. These shares are subject to repurchase rights whereby the Company has the right to repurchase the unvested shares at price per share equal to the lesser of (i) the fair market value of the shares at the time the right of repurchase is exercised and (ii) the original issuance price of the shares. A summary of the status of unvested restricted stock is presented below: Number of Shares Weighted Average Grant Date Fair Value Unvested at January 1, 2014 229,208 $ 0.51 Vested (208,520 ) 0.40 Unvested at December 31, 2014 20,688 0.57 Vested (14,203 ) 0.55 Unvested at December 31, 2015 6,485 0.57 Share-based compensation expense for restricted stock granted is reflected in the statements of operations as follows (in thousands): Year Ended December 31, 2014 2015 Research and development $ 127 $ — General and administrative 17 — Total $ 144 $ — As of December 31, 2014 and 2015, the Company had $0 of unrecognized compensation expense related to unvested restricted stock.

Commitments and contingencies

Commitments and contingencies	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and contingencies	10. Commitments and contingencies Lease commitment summary The Company leases office space under non-cancelable operating leases which expire in March 2017. The operating leases have renewal options and rent escalation clauses. Minimum lease payments were as follows at September 30, 2016 (in thousands): 2016 $ 23 2017 23 Total minimum lease payments $ 46 Rent expense, net of sublease income, was $61,000 for the nine months ended September 30, 2016 and 2015. Contract service providers In the course of the Company’s normal business operations, it has agreements with contract service providers to assist in the performance of its research and development, clinical research and manufacturing. Substantially all of these contracts are on an as needed basis.	12. Commitments and contingencies Lease commitment summary The Company leases office space under non-cancelable operating leases which expire in March 2017. The operating leases have renewal options and rent escalation clauses. The following table presents future minimum commitments of the Company due under non-cancelable operating leases with original or remaining terms in excess of one year. Minimum lease payments were as follows at December 31, 2015 (in thousands): 2016 $ 90 2017 23 Total minimum lease payments $ 113 Rent expense, net of sublease income, was $198,000 and $150,000 for years ended December 31, 2014 and 2015, respectively. Litigation The Company is not party to any litigation and does not have contingency reserves established for any litigation liabilities. Contract service providers In the course of the Company’s normal business operations, it has agreements with contract service providers to assist in the performance of its research and development, clinical research and manufacturing. Substantially all of these contracts are on an as needed basis. Employment contracts The Company has employment agreements with its executive officers and has at will employment contracts with substantially all other employees providing for salary, benefits and bonuses.

License agreements

License agreements	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Text Block [Abstract]
License agreements	11. License agreements In August 2014, the Company entered into a royalty-bearing license agreement with NovaMedica LLC (“NovaMedica”). Under this agreement, the Company granted to NovaMedica the right to use the Company’s intellectual property to develop and commercialize the intended products (the “Covered Products”) and to have the exclusive right to sell those products in Russia and specified adjacent territories involving the use of the corticosteroid triamcinolone acetonide as the sole active pharmaceutical ingredient for administration in the suprachoroidal space. In connection with this royalty-bearing license, NovaMedica made an upfront payment to the Company of $200,000. The Company is currently developing product candidates that when completed would be subject to this license giving NovaMedica the exclusive right to then sell the products in the specified geographic territories. In mid-December 2015, the Company received positive results from the Phase 2 clinical trial relating to the product candidate and determined, based on these results, that the intellectual property could become commercially feasible. Beginning in the first quarter ended March 31, 2016, the Company began recognizing the $200,000 to revenue over the period of time to complete clinical development and commercialization of the Covered Products and the beginning of the first set of patent expirations in 2027. The Company recorded $5,000 and $15,000 of license revenue during the three and nine months ended September 30, 2016, respectively, for this license agreement. NovaMedica is jointly owned by Rusnano MedInvest LLC, or Rusnano MedInvest, and Domain Russia Investments Limited. RMI, which beneficially owns approximately 11% of the Company’s voting securities, is a wholly owned subsidiary of Rusnano MedInvest. In April 2015, the Company entered into a license and collaboration agreement (the “Spark Agreement”) with Spark Therapeutics, Inc. (“Spark”) under which Spark could acquire the exclusive rights to license the Company’s microinjector technology and access to the suprachoroidal space within the eye for development and ultimate commercialization of Spark’s gene therapy treatments to be delivered via the microinjector. In conjunction with executing the Spark Agreement, Spark made an upfront, non-refundable payment to the Company of $500,000. In February 2016, the initial study was completed and Spark elected not to extend the arrangement nor license the technology which terminated the agreement in accordance with the agreement terms. During the quarter ended March 31, 2016, the Company recorded as revenue the $500,000 upfront payment as the amount was non-refundable and the Company had no further obligations under this arrangement.	13. License agreements In July 2012, the Company entered into an Exclusive License Agreement with Emory University and Georgia Tech Research Corporation (“Emory/GTRC”), whereby the Company purchased a license for Methods and Devices For Drug Delivery Using Microneedles. The Company paid $30,000 for the license and made a milestone payment of $35,000 during the year ended December 31, 2012. No payments were made to Emory/GTRC during the years ended December 31, 2014 or 2015. The Exclusive License Agreement requires the Company to make a milestone payment upon the occurrence of a specified event relating to the commercialization of a drug developed using the licensed patents. Beginning on the third anniversary of this license agreement, the Company will be obligated to pay an annual license maintenance fee of $25,000, which will continue until the first commercial sale of a product covered by the licensed patents. Additionally, the Company will owe a low single-digit royalty on any worldwide net product sales related to the licensed patents, with minimum annual royalties of $15,000 after commercialization. The minimum annual royalty increases thereafter to $100,000. In August 2014, the Company entered into a royalty-bearing license agreement with NovaMedica LLC (“NovaMedica”). Under this agreement, the Company granted to NovaMedica the right to use the Company’s intellectual property to develop and commercialize the intended products (the “Covered Products”) and to have the exclusive right to sell those products in Russia and specified adjacent territories involving the use of the corticosteroid triamcinolone acetonide as the sole active pharmaceutical ingredient for administration in the suprachoroidal space. In addition, NovaMedica agreed to make royalty payments equal to the amount of any royalties the Company owes to Emory or GTRC pursuant to the Emory/GTRC License Agreement as a result of NovaMedica’s sales of products and services covered by the license granted to NovaMedica, up to a maximum of a low single-digit percentage of net sales of such products or services by NovaMedica. NovaMedica has also agreed to make milestone payments, totaling $12.7 million in the aggregate, primarily related to the achievement of specified commercial product sales. The agreement also includes provisions whereby the Company and NovaMedica may enter into a future development and research collaboration agreement and a supply agreement for the Company to manufacture and supply the Covered Products. Terms and conditions of these agreements would be negotiated in good faith in the future. The term of the NovaMedica license agreement will expire upon the expiration of the last-to-expire valid claim within the patents licensed to NovaMedica pursuant to the agreement. Either the Company or NovaMedica may terminate the agreement upon written notice in the event of the other party’s material breach that is not cured within 20 business days of receiving written notice requesting a cure of a payment breach, and within 60 business days of receiving written notice requesting a cure in the case of all other breaches. Each party also has the right to terminate the agreement in the event of the other party’s bankruptcy or insolvency. The Company may terminate the agreement immediately upon written notice in the event that NovaMedica commences or participates in any action challenging the validity or enforceability of the patents licensed to NovaMedica under the agreement. In connection with this royalty-bearing license, NovaMedica made an upfront payment to the Company of $200,000. The Company is currently developing product candidates that when completed would be subject to this license giving NovaMedica the exclusive right to then sell the products in the specified geographic territories. During 2014 and 2015, the Company deferred the $200,000 given the early stage of development of the intellectual property and uncertainty regarding commercial feasibility. In mid-December 2015, the Company received positive results from the Phase 2 clinical trial relating to the product candidate and determined, based on these results, that the intellectual property could become commercially feasible. Beginning in the first quarter ended March 31, 2016, the Company began recognizing the $200,000 to revenue over the period of time to complete clinical development and commercialization of the Covered Products and the beginning of the first set of patent expirations in 2027. NovaMedica is jointly owned by Rusnano MedInvest LLC, or Rusnano MedInvest, and Domain Russia Investments Limited. RMI, which beneficially owns approximately 11% of the Company’s voting securities, is a wholly owned subsidiary of Rusnano MedInvest. On April 27, 2015, the Company entered into a license and collaboration agreement (the “Spark Agreement”) with Spark Therapeutics, Inc. (“Spark”) under which Spark could acquire the exclusive rights to license the Company’s microinjector technology and access to the suprachoroidal space within the eye (collectively “the IP”) for development and ultimate commercialization of Spark’s gene therapy treatments to be delivered via the microinjector. If Spark made the decision to license the IP, Spark would be responsible for the costs of the future development and commercialization. The Company would be responsible for providing the microinjector technology as well as other defined support to Spark as part of Spark’s development efforts. The Spark Agreement was structured to allow Spark certain periods of time (the “Option Periods”) before actually entering into the IP license. In conjunction with executing the Spark Agreement, Spark made an upfront, non-refundable payment to the Company of $500,000. During the initial Option Period, the parties agreed to have a third-party research organization perform an initial preclinical study under the direction of the Company. At any time during this Option Period, Spark could exercise its option to license the IP by paying an additional $2.0 million, or could elect to initiate a second Option Period during which the Company and Spark would conduct further studies specified in the Spark Agreement. If Spark elected to initiate the second Option Period, Spark would be required to pay the Company $1.0 million. If Spark exercised its option to license the IP during the second Option Period, then Spark would be required to pay the Company an additional $3.0 million. If Spark did not exercise its option to license the IP or elect to initiate the second Option Period, then the Spark Agreement would terminate at the end of the first Option Period. Spark had the right to terminate the Spark Agreement at any time upon written notice to the Company. The Company and Spark could also terminate the Spark Agreement upon 90 days’ written notice in the event of an uncured material breach by the other party. If Spark decided to license the technology, the Company would be eligible to receive aggregate payments of up to $13.5 million from Spark upon the achievement of specified future development and commercialization milestones as described in the agreement, as well as aggregate payments of up to $12.0 million upon the achievement of specified annual net sales milestones. In addition, the Company would be eligible to receive low to mid single-digit percentage royalties on net sales of licensed products. Subject to specified exceptions, the license would expire on a licensed product-by-licensed product basis and on a country-by-country basis upon the expiration of the specified licensed intellectual property. In evaluating the Option Periods granted to Spark to determine whether Spark would license the IP, the Company determined that these Option Periods combined had stand-alone value apart from the IP license as Spark was deriving value from its ability to evaluate the technology through defined preclinical studies conducted by the Company and Spark during these Option Periods. The Company also determined that the two Option Periods represented one unit of accounting providing Spark with an overall evaluation period in which to decide whether to license the IP. This determination was made based on the fact that the planned studies are not independent of each other, but instead are designed to build on the results of the prior studies in order to further the preclinical analysis to be in a position to ultimately file an investigational new drug application and begin the onset of clinical trials in human patients as contemplated in the Spark Agreement. The Company determined that the $500,000 upfront payment should be recognized to revenue over the expected period of time to perform and complete the planned studies during the Option Periods contemplated at the date the agreement was executed. The Company estimated that this time period would be approximately 30 months from the start of the initial study to the end and evaluation of the planned studies to be performed during the Option Periods. The Company did not record any revenue from the $500,000 upfront payment during 2015. In February 2016, the initial study was completed and Spark elected not to extend the arrangement nor license the technology which terminated the agreement in accordance with the agreement terms. During the quarter ended March 31, 2016, the Company recorded as revenue the $500,000 upfront payment as the amount was non-refundable and the Company had no further obligations under this arrangement.

Collaborative agreement

Collaborative agreement	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative agreement	12. Collaborative agreement In January 2013, the Company entered into a collaborative research agreement with a stockholder, whereby the parties agreed to conduct feasibility studies for certain compounds. Each party to the collaborative research agreement will bear its own costs, except that certain costs incurred by the Company are limited to a defined maximum amount. The Company incurred research and development costs in relation to the collaborative research agreement of $85,000 and $124,000 for the nine months ended September 30, 2016 and 2015, respectively.	14. Collaborative agreement In January 2013, the Company entered into a collaborative research agreement with one of the holders of the Series A-1 preferred stock, whereby the two parties agreed to conduct feasibility studies for certain compounds. Each party to the collaborative research agreement will bear its own costs, except that certain costs incurred by the Company are limited to a defined maximum amount. The Company incurred research and development costs in relation to the collaborative research agreement of $98,000 and $145,000 for the years ended December 31, 2014 and 2015, respectively.

Fair value measurements

Fair value measurements	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair value measurements	14. Fair value measurements The Company records certain financial assets and liabilities at fair value in accordance with the provisions of ASC Topic 820, Fair Value Measurements and Disclosures • Level 1—Unadjusted quoted prices in active, accessible markets for identical assets or liabilities. • Level 2—Other inputs that are directly or indirectly observable in the marketplace. • Level 3—Unobservable inputs that are supported by little or no market activity. The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The Company’s material financial instruments at September 30, 2016 and December 31, 2015 consisted primarily of cash and cash equivalents, short-term investments, long-term debt and stock purchase warrant liabilities. The fair value of cash and cash equivalents, other current assets and accounts payable approximate their respective carrying values due to the short term nature of these instruments. The fair value of long-term debt approximates the carrying value due to variable interest rates that correspond to market rates. The Company has determined its short-term investments, comprised of certificates of deposit, corporate bonds and government bonds and agency obligations, to be Level 2 in the fair value hierarchy. The fair value was determined using a market approach, based on prices and other relevant information generated by market transactions involving similar assets. The short-term investments consist of investments with original maturity dates from date of acquisition of 90 to 365 days and are classified as available-for-sale. The Company has determined its stock purchase warrants liability to be Level 3 in the fair value hierarchy. There were no significant transfers between Levels 1, 2 and 3 during the nine months ended September 30, 2016 and the year ended December 31, 2015. The following tables summarize the fair value of financial assets and liabilities that are measured at fair value and the classification by level of input within the fair value hierarchy (in thousands): September 30, 2016 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Cash and money markets $ 35,666 $ — $ — $ 35,666 Certificates of deposit 5,868 — — 5,868 Government bonds 2,499 — — 2,499 Agency obligations — 8,530 — 8,530 Corporate bonds — 4,356 — 4,356 Total financial assets $ 44,033 $ 12,886 $ — $ 56,919 Financial Liabilities: Stock purchase warrants $ — $ — $ 251 $ 251 December 31, 2015 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Money markets (included in cash and cash equivalents) $ 20,076 $ — $ — $ 20,076 Financial Liabilities: Stock purchase warrants $ — $ — $ 258 $ 258 Prior to the IPO, the Company estimated the fair value of its warrants to purchase preferred stock using an option pricing model that included three valuation scenarios, a non-IPO scenario and two IPO scenarios. Under the IPO scenarios, the Company calculated the value of the warrant based on a call option of the common share at IPO (assuming the underlying preferred stock would convert to common stock) given the time to exit and the term of the warrants stipulated in the contract. The Company then applied a discount for lack of marketability. Changes in the fair value of the stock purchase warrants were recorded in other income (expense), net in the statements of operations. Subsequent to the IPO, the Company used the Black-Scholes option pricing model to estimate the fair value of the remaining warrants. The estimates in the Black-Scholes option pricing model are based, in part, on assumptions, including but not limited to the volatility of comparable public companies, the expected life of the warrants, the risk-free interest rate and the fair value of the underlying warrants. The following table summarizes the changes in fair value of the Level 3 liability, stock purchase warrants (in thousands): Level 3 Liabilities Nine Months Ended September 30, Year Ended December 31, 2016 2015 Stock purchase warrants Balance at beginning of period $ 258 $ 42 Issuance of stock purchase warrants — 164 Exercise of stock purchase warrants (23 ) — Net increase in fair value remeasurement 16 52 Balance at end of period $ 251 $ 258	15. Fair value measurements The Company records certain financial assets and liabilities at fair value in accordance with the provisions of ASC Topic 820, Fair Value Measurements and Disclosures • Level 1—Unadjusted quoted prices in active, accessible markets for identical assets or liabilities. • Level 2—Other inputs that are directly or indirectly observable in the marketplace. • Level 3—Unobservable inputs that are supported by little or no market activity. The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The Company’s material financial instruments at December 31, 2014 and 2015 consisted primarily of cash and cash equivalents, long-term debt and stock purchase warrant liabilities. The fair value of cash and cash equivalents, other current assets and accounts payable approximate their respective carrying values due to the short term nature of these instruments. The fair value of long-term debt approximates the carrying value due to variable interest rates that correspond to market rates. The Company has determined its stock purchase warrants liability to be a Level 3 fair value measurement. There were no significant transfers between Levels 1, 2 and 3 during the years ended December 31, 2014 and 2015. The following tables summarize the fair value of financial assets and liabilities that are measured at fair value and the classification by level of input within the fair value hierarchy (in thousands): December 31, 2014 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Money markets (included in cash and cash equivalents) $ 7,951 $ — $ — $ 7,951 Financial Liabilities: Stock purchase warrants $ — $ — $ 42 $ 42 December 31, 2015 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Money markets (included in cash and cash equivalents) $ 20,076 $ — $ — $ 20,076 Financial Liabilities: Stock purchase warrants $ — $ — $ 258 $ 258 The determination of the fair value of the stock purchase warrants is discussed in Note 10. Changes in the fair value of the stock purchase warrants are recorded in other income (expense), net in the statements of operations. The following table summarizes the changes in fair value of the Level 3 liability, stock purchase warrants (in thousands): Level 3 Liabilities Year Ended December 31, 2014 2015 Stock purchase warrants Balance at beginning of period $ 24 $ 42 Issuance of stock purchase warrants — 164 Net increase (decrease) in fair value remeasurement 18 52 Balance at period end of period $ 42 $ 258

Subsequent events

Subsequent events	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent events	16. Subsequent events Subsequent to September 30, 2016, we entered into a new office lease agreement for our corporate headquarters, under which we have agreed to lease approximately 20,000 square feet of space in Alpharetta, Georgia. We expect to move into this new space in the first half of 2017. Under this lease, we will pay an initial annual base rent of $421,740, or $35,145 per month, subject to an increase of 3% per year.	16. Subsequent events Reverse stock split On May 11, 2016, the Company effected a 1-for-2.2 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 convertible preferred stock (see Notes 8 and 9). Accordingly, all share and per share amounts for all periods presented in these 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.

Available-for sale securities

Available-for sale securities	9 Months Ended
	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Available-for sale securities	13. Available-for sale securities The following table summarizes the Company’s available-for-sale investments as of September 30, 2016: September 30, 2016 Amortized Cost Unrealized Loss Fair Value Government bonds and agency obligations $ 11,032 $ (3 ) $ 11,029 Certificates of deposit 4,658 — 4,658 Corporate bonds 4,358 (2 ) 4,356 Total available-for-sale investments $ 20,048 $ (5 ) $ 20,043

Significant accounting polici25

Significant accounting policies (Policies)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of presentation	Basis of presentation The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”).	Basis of presentation The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”).
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 reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of income and expenses during the reporting periods. Significant items subject to such estimates and assumptions include the accounting for useful lives to calculate depreciation and amortization, accrued liabilities, share-based compensation expense and income tax valuation allowance. Actual results could differ from these 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 reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and reported amounts of income and expenses during the reporting periods. Significant items subject to such estimates and assumptions include the accounting for useful lives to calculate depreciation and amortization, accrued liabilities, share-based compensation expense and income tax valuation allowance. Actual results could differ from these estimates.
Segment information		Segment information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment. All operations are located in the United States.
Property and equipment, net		Property and equipment, net Property and equipment is recorded at historical cost. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets. Repairs and maintenance are expensed when incurred. Upon retirement or sale, the cost of the assets disposed of and the related accumulated depreciation are removed from the accounts, and any resulting gain or loss is included in the determination of net income.
Cash equivalents	Cash equivalents Cash equivalents consist of short-term, highly liquid investments with an original term of three months or less at the date of purchase.	Cash equivalents Cash equivalents consist of short-term, highly liquid investments with an original term of three months or less at the date of purchase.
Concentration of credit risk arising from cash deposits in excess of insured limits	Concentration of credit risk arising from cash deposits in excess of insured limits The Company maintains its cash in bank deposits that at times may exceed federally insured limits. The Company has not experienced any loss in such accounts. The Company believes it is not exposed to any significant risks with respect to its cash balances.	Concentration of credit risk arising from cash deposits in excess of insured limits The Company maintains its cash in bank deposits that at times may exceed federally insured limits. The Company has not experienced any loss in such accounts. The Company believes it is not exposed to any significant risks with respect to its cash balances.
Deferred offering costs		Deferred offering costs The Company capitalizes certain legal, accounting and other third-party fees that are directly associated with in-process equity financings as other assets until such financings are consummated. After consummation of the equity financing, these costs are recorded in stockholders’ equity (deficit) as a reduction of additional paid-in capital generated as a result of the offering or as a reduction to the carrying value of preferred stock issued, if such stock is classified outside of stockholders’ equity (deficit). Should the equity financing no longer be considered probable of being consummated, the deferred offering costs would be expensed immediately as a charge to operating expenses in the statement of operations. As of December 31, 2014, the Company had recorded $1.8 million of deferred offering costs. In September 2015, $1.9 million of deferred offering costs were charged to operating expenses due to the postponement of the equity financing. As of December 31, 2015, the Company had recorded $0.4 million of deferred offering costs in connection with a new equity financing.
Research and development costs	Research and development costs Research and development costs are charged to expense as incurred and include, but are not limited to: • employee-related expenses, including salaries, benefits, travel and share-based compensation expense for research and development personnel; • expenses incurred under agreements with contract research organizations, contract manufacturing organizations and consultants that conduct clinical and preclinical studies; • costs associated with preclinical and development activities; • costs associated with technology and intellectual property licenses; • costs for the Company’s research and development facility; and • depreciation expense for assets used in research and development activities. Costs for certain development activities, such as clinical studies, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the patterns of costs incurred, and are reflected in the financial statements as prepaid or accrued expense, which are reported in accounts payable. No material adjustments to these estimates have been recorded in these financial statements.	Research and development costs Research and development costs are charged to expense as incurred and include, but are not limited to: • employee-related expenses, including salaries, benefits, travel and share-based compensation expense for research and development personnel; • expenses incurred under agreements with contract research organizations, contract manufacturing organizations and consultants that conduct clinical and preclinical studies; • costs associated with preclinical and development activities; • costs associated with technology and intellectual property licenses; • costs for the Company’s research and development facility; and • depreciation expense for assets used in research and development activities. Costs for certain development activities, such as clinical studies, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the patterns of costs incurred, and are reflected in the financial statements as prepaid or accrued expense, which are reported in accounts payable. No material adjustments to these estimates have been recorded in these financial statements.
Share-based compensation	Share-based compensation Compensation cost related to share-based awards granted to employees is measured at grant date, based on the estimated fair value of the award. The Company estimates the fair value of stock options using a Black-Scholes option pricing model. Compensation expense for options granted to non-employees is determined as the fair value of consideration received or the fair value of the equity instruments issued, whichever is more reliably measured. The fair value of restricted stock awards is determined based on the fair value of the Company’s common stock on the date of grant. Share-based compensation costs are expensed on a straight-line basis (net of estimated forfeitures) over the relevant vesting period. The fair value of awards granted to non-employees is re-measured each period until the related service is complete. All share-based compensation costs are recorded in general and administrative or research and development costs in the statements of operations based upon the underlying employees’ roles within the Company.	Share-based compensation Compensation cost related to share-based awards granted to employees is measured at grant date, based on the estimated fair value of the award. The Company estimates the fair value of stock options using a Black-Scholes option pricing model. Compensation expense for options granted to non-employees is determined as the fair value of consideration received or the fair value of the equity instruments issued, whichever is more reliably measured. The fair value of restricted stock awards is determined based on the fair value of the Company’s common stock on the date of grant. Share-based compensation costs are expensed on a straight-line basis (net of estimated forfeitures) over the relevant vesting period. The fair value of awards granted to non-employees is re-measured each period until the related service is complete. All share-based compensation costs are recorded in general and administrative or research and development costs in the statements of operations based upon the underlying employees’ roles within the Company.
Debt discount		Debt discount The Company follows the authoritative guidance in Accounting Standards Codification (“ASC”) 470-20-25-2, Debt with Conversion of Other Options
Fair value measurements		Fair value measurements The Company records certain financial assets and liabilities at fair value in accordance with the provisions of ASC Topic 820, Fair Value Measurements and Disclosures
Stock purchase warrants		Stock purchase warrants The Company accounts for stock purchase warrants as liabilities based upon the characteristics and provisions of the underlying instruments. These liabilities are recorded at their fair value on the date of issuance within other non-current liabilities on the balance sheet and are remeasured on each subsequent reporting date, with fair value changes recognized as income (decreases in fair value) or expenses (increases in fair value) in other income (expense), net in the statements of operations. The fair value of these liabilities is estimated using the Black-Scholes method.
Income taxes		Income taxes Deferred tax assets or liabilities are recorded for temporary differences between financial statement and tax basis of assets and liabilities, using enacted rates in effect for the year in which the differences are expected to reverse. A valuation allowance is recorded if it is more likely than not that a deferred tax asset will not be realized. The Company has provided a full valuation allowance on its deferred tax assets, which primarily consist of cumulative net operating losses of $14.2 million for the period from May 26, 2011 (inception) to December 31, 2015. Due to its history of operating losses since inception and losses expected to be incurred in the foreseeable future, a full valuation allowance was considered necessary.
Recent accounting pronouncements	Recent accounting pronouncements In August 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-15, Statement of Cash Flows Classification of Certain Cash Receipts and Cash Payments In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718). In February 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842), In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements-Going Concern (Subtopic 205-40): Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers	Recent accounting pronouncements In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-09, Compensation-Stock Compensation (Topic 718) In February 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842), In August 2014, the FASB issued ASU 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern,
Unaudited interim financial information	Unaudited interim financial information The accompanying balance sheet as of September 30, 2016, statements of operations for the nine months ended September 30, 2016 and 2015 and statements of cash flows for the nine months ended September 30, 2016 and 2015 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2016 and its results of its operations for the nine months ended September 30, 2016 and 2015 and its cash flows for the nine months ended September 30, 2016 and 2015. The financial data and other information disclosed in these notes related to the nine months ended September 30, 2016 and 2015 are unaudited. The results for the nine months ended September 30, 2016 are not indicative of results to be expected for the year ending December 31, 2016, any other interim periods or any future year or period. These unaudited financial statements should be read in conjunction with the audited financial statements and related footnotes for the year ended December 31, 2015, which are included in the Company’s prospectus dated June 1, 2016, as filed pursuant to Rule 424(b) under the Securities and Exchange Act of 1933 filed, as amended, with the SEC.
Reverse stock split	Reverse stock split On May 11, 2016, the Company effected a 1-for-2.2 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 convertible preferred stock. Accordingly, all share and per share amounts for all periods presented in these 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. The adjustment to the conversion ratio for the Series C convertible preferred stock also included an anti-dilution adjustment based on the initial public offering price of the Company’s common stock.
Short-term investments	Short-term investments Short-term investments are investments with original maturities of between 90 and 365 days when purchased and are comprised of corporate and government bonds and government agency securities. The Company classifies its short-term investments as available-for-sale securities. Short-term investments are recorded at fair value and unrealized gains and losses are recorded within accumulated other comprehensive income (loss) until realized. In addition, the Company evaluates the short-investments with unrealized losses to determine whether such losses are other-than-temporary.

Significant accounting polici26

Significant accounting policies (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Summary of Anti-dilutive Securities Excluded from Calculation of Weighted Average Common Shares Outstanding	The Company’s potential common stock equivalents that have been excluded from the computation of diluted net loss per share for all periods presented because of their antidilutive effect consisted of the following: Year Ended December 31, 2014 2015 Convertible preferred stock 7,074,961 9,472,530 Outstanding stock options 1,098,486 1,261,637 Unvested restricted stock 20,688 6,485 Stock purchase warrants 900,724 146,298 9,094,859 10,886,950

Property and equipment, net (Ta

Property and equipment, net (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (dollar amounts in thousands): Estimated Useful Lives (Years) September 30, 2016 December 31, 2015 Furniture and fixtures 5 $ 69 $ 66 Machinery and equipment 5 121 121 Computer equipment 3 27 27 Leasehold improvements Lesser of Useful life or remaining lease term 45 45 262 259 Less: Accumulated depreciation (152 ) (103 ) $ 110 $ 156	Property and equipment, net consisted of the following (dollar amounts in thousands): Estimated Useful Lives (Years) December 31, 2014 2015 Furniture and fixtures 5 $ 95 $ 66 Machinery and equipment 5 105 121 Computer equipment 3 27 27 Leasehold improvements Lesser of useful life or remaining lease term 33 45 260 259 Less: Accumulated depreciation (55 ) (103 ) $ 205 $ 156

Accrued liabilities (Tables)

Accrued liabilities (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): September 30, 2016 December 31, 2015 Accrued research and development $ 790 $ 569 Accrued bonuses 478 530 Accrued professional fees 78 668 Accrued vacation 88 64 Accrued interest payable 5 15 Accrued expense 117 139 $ 1,556 $ 1,985	Accrued liabilities consisted of the following (in thousands): December 31, 2014 2015 Accrued research and development $ 427 $ 569 Accrued bonuses 279 530 Accrued professional fees 178 668 Accrued vacation 53 64 Accrued interest payable — 15 Accrued expense 220 139 $ 1,157 $ 1,985

Long-term debt (Tables)

Long-term debt (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
Scheduled Payments for the Loan Agreement	As of September 30, 2016, the scheduled payments for the loan agreement, including the scheduled final payment in 2020, were as follows (in thousands): Year Ending December 31, Principal Interest and Final Payment Total 2016 $ — $ 158 $ 158 2017 — 608 608 2018 3,200 476 3,676 2019 3,200 234 3,434 2020 1,600 545 2,145 $ 8,000 $ 2,021 $ 10,021	As of December 31, 2015, the annual payments for the loan agreement, including the scheduled final payment in 2018, were as follows (in thousands): Year Ending December 31, Principal Interest and Final Payment Total 2016 $ 1,733 $ 166 $ 1,899 2017 2,400 96 2,496 2018 1,867 354 2,221 $ 6,000 $ 616 $ 6,616

Income taxes (Tables)

Income taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Net Deferred Tax Assets	Significant components of the Company’s net deferred income tax assets consist of the following (in thousands): December 31, 2014 2015 Current Deferred tax asset (liability) Non-deductible accrued expenses $ 20 $ 230 Deferred rent 4 3 Valuation allowance (24 ) (233 ) Net current deferred tax asset $ — $ — Non-current Deferred tax asset (liability) Stock compensation expense $ 70 $ 88 Net operating loss carryforwards 7,891 14,169 Depreciation differences (31 ) (28 ) Federal tax credits 447 850 State tax credits 196 262 Deferred revenue — 77 Deferred rent 4 1 Charitable contributions 3 3 Valuation allowance (8,580 ) (15,422 ) Net non-current deferred tax asset $ — $ —
Schedule of Statutory and Effective Income Tax Rate Reconciliation	A reconciliation of the statutory tax rates and the effective tax rates is as follows: Year Ended December 31, 2014 2015 U.S. federal tax rate 34.00 % 34.00 % State tax rate 4.41 4.54 Permanent difference and other (1.15 ) (1.26 ) Tax credit 4.54 2.66 Valuation allowance (41.79 ) (39.94 ) 0.00 % 0.00 %

Convertible debt (Tables)

Convertible debt (Tables)	12 Months Ended
	Dec. 31, 2015
Text Block [Abstract]
Activity Convertible Preferred Stock	The following table summarizes the activity of convertible preferred stock (dollar amounts in thousands, except per share amounts): Series A Preferred Stock Series A-1 Preferred Stock Series B Preferred Stock Series C Preferred Stock Total Convertible Preferred Stock Shares Amount Shares Amount Shares Amount Shares Amount Balance at January 1, 2014 5,198,826 $ 4,040 4,356,931 $ 7,831 — $ — — $ — $ 11,871 Issuance of Series B at $2.69783 per share on August 29, 2014, net of issuance cost of $236 — — — — 4,811,259 11,501 — — 11,501 Conversion of promissory notes and interest payable at $2.69783 per share on August 29, 2014 — — — — 1,197,943 3,232 — — 3,232 Accretion of stock issuance costs — 46 — 27 — 158 — — 231 Balance at December 31, 2014 5,198,826 4,086 4,356,931 7,858 6,009,202 14,891 — — 26,835 Issuance of Series C at $3.7917 per share in November and December 2015, net of issuance cost of $46 — — — — — — 5,274,674 19,954 19,954 Accretion of stock issuance costs — — — 42 — 481 — 2 525 Balance at December 31, 2015 5,198,826 4,086 4,356,931 7,900 6,009,202 15,372 5,274,674 19,956 47,314

Stock purchase warrants (Tables

Stock purchase warrants (Tables)	12 Months Ended
	Dec. 31, 2015
Text Block [Abstract]
assumptions for fair value calculation of warrants	Key assumptions utilized in the fair value calculation for the warrants appear in the table below: December 31, 2014 2015 Expected term (years) 5.00 5.00 Volatility 109.60% 113.50% Risk-free interest rate 2.10% 2.13% Dividend yield 0.00% 0.00%

Share-based compensation (Table

Share-based compensation (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of Share-based Compensation Expense	Share-based compensation expense for options granted is reflected in the statements of operations as follows (in thousands): Nine Months Ended September 30, 2016 2015 Research and development $ 375 $ 229 General and administrative 401 273 Total $ 776 $ 502	The total share-based compensation expense recognized is reflected in the statements of operations as follows (in thousands): Year Ended December 31, 2014 2015 Research and development $ 218 $ 327 General and administrative 209 378 Total $ 427 $ 705 The Company has granted stock option awards to employees, directors and consultants. Share-based compensation expense for options granted is reflected in the statements of operations as follows (in thousands): Year Ended December 31, 2014 2015 Research and development $ 91 $ 327 General and administrative 192 378 Total $ 283 $ 705 Share-based compensation expense for restricted stock granted is reflected in the statements of operations as follows (in thousands): Year Ended December 31, 2014 2015 Research and development $ 127 $ — General and administrative 17 — Total $ 144 $ —
Key Assumptions Utilized In the Fair Value Calculation for the Warrants		The following table sets forth the weighted average assumptions utilized in the fair value calculation for the underlying common stock for the years ended December 31, 2014 and 2015. Year Ended December 31, 2014 2015 Expected term (years) 7.00 7.00 Expected stock price volatility 85.64% 86.63% Risk-free interest rate 1.99% 2.09% Expected dividend yield 0.00% 0.00%
Stock Option Activity Under Stock Option Plan		The following table provides additional information about the Company’s stock options that were outstanding and exercisable at December 31, 2015 (aggregate intrinsic values in thousands): Exercise Price Options Outstanding Weighted Average Exercise Price Aggregate Intrinsic Value Average Remaining Contractual Life (Years) Options Exercisable Weighted Average Exercise Price Aggregate Intrinsic Value $ 0.02 11,363 5.9 11,363 0.15 72,987 6.4 67,510 0.40 544,493 7.6 329,131 3.08 31,818 8.6 11,267 3.41 311,357 9.0 79,254 5.57 232,802 9.9 — 6.16 56,817 9.5 2,272 1,261,637 $ 2.40 $ 7,210 500,797 $ 0.92 $ 3,606
Summary of Activity Related to Stock Options	The following table summarizes the activity related to stock options during the nine months ended September 30, 2016: Number of Shares Weighted Average Exercise Price Options outstanding at January 1, 2016 1,261,638 $ 2.41 Granted 174,736 6.79 Exercised (1,326 ) 0.40 Cancelled/Forfeited (20,454 ) 6.03 Options outstanding at September 30, 2016 1,414,594 2.90 Options exercisable at December 31, 2015 500,797 0.92 Options exercisable at September 30, 2016 686,439 1.22	The following table summarizes the activity related to stock options: Number of Shares Weighted Average Exercise Price Options outstanding at January 1, 2014 770,062 $ 0.34 Granted 376,126 3.38 Exercised (24,803 ) 0.17 Cancelled/Forfeited (22,899 ) 0.15 Options outstanding at December 31, 2014 1,098,486 1.39 Granted 289,619 5.68 Exercised (50,980 ) 0.27 Cancelled/Forfeited (75,488 ) 1.67 Options outstanding at December 31, 2015 1,261,637 2.40 A summary of the status of unvested restricted stock is presented below: Number of Shares Weighted Average Grant Date Fair Value Unvested at January 1, 2014 229,208 $ 0.51 Vested (208,520 ) 0.40 Unvested at December 31, 2014 20,688 0.57 Vested (14,203 ) 0.55 Unvested at December 31, 2015 6,485 0.57

Commitments and contingencies (

Commitments and contingencies (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Commitments Due Under Non-Cancelable Operating Leases	Minimum lease payments were as follows at September 30, 2016 (in thousands): 2016 $ 23 2017 23 Total minimum lease payments $ 46	Minimum lease payments were as follows at December 31, 2015 (in thousands): 2016 $ 90 2017 23 Total minimum lease payments $ 113

Fair value measurements (Tables

Fair value measurements (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Summary of Assets and Liabilities Measured at Fair Value	The following tables summarize the fair value of financial assets and liabilities that are measured at fair value and the classification by level of input within the fair value hierarchy (in thousands): September 30, 2016 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Cash and money markets $ 35,666 $ — $ — $ 35,666 Certificates of deposit 5,868 — — 5,868 Government bonds 2,499 — — 2,499 Agency obligations — 8,530 — 8,530 Corporate bonds — 4,356 — 4,356 Total financial assets $ 44,033 $ 12,886 $ — $ 56,919 Financial Liabilities: Stock purchase warrants $ — $ — $ 251 $ 251 December 31, 2015 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Money markets (included in cash and cash equivalents) $ 20,076 $ — $ — $ 20,076 Financial Liabilities: Stock purchase warrants $ — $ — $ 258 $ 258	The following tables summarize the fair value of financial assets and liabilities that are measured at fair value and the classification by level of input within the fair value hierarchy (in thousands): December 31, 2014 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Money markets (included in cash and cash equivalents) $ 7,951 $ — $ — $ 7,951 Financial Liabilities: Stock purchase warrants $ — $ — $ 42 $ 42 December 31, 2015 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Money markets (included in cash and cash equivalents) $ 20,076 $ — $ — $ 20,076 Financial Liabilities: Stock purchase warrants $ — $ — $ 258 $ 258
Summarizes the Changes in Fair Value of the Level 3 Liability, Stock Purchase Warrants	The following table summarizes the changes in fair value of the Level 3 liability, stock purchase warrants (in thousands): Level 3 Liabilities Nine Months Ended September 30, Year Ended December 31, 2016 2015 Stock purchase warrants Balance at beginning of period $ 258 $ 42 Issuance of stock purchase warrants — 164 Exercise of stock purchase warrants (23 ) — Net increase in fair value remeasurement 16 52 Balance at end of period $ 251 $ 258	The following table summarizes the changes in fair value of the Level 3 liability, stock purchase warrants (in thousands): Level 3 Liabilities Year Ended December 31, 2014 2015 Stock purchase warrants Balance at beginning of period $ 24 $ 42 Issuance of stock purchase warrants — 164 Net increase (decrease) in fair value remeasurement 18 52 Balance at period end of period $ 42 $ 258

Available-for sale securities (

Available-for sale securities (Tables)	9 Months Ended
	Sep. 30, 2016
Investments, Debt and Equity Securities [Abstract]
Summary of Company's Available-For-Sale Investments	The following table summarizes the Company’s available-for-sale investments as of September 30, 2016: September 30, 2016 Amortized Cost Unrealized Loss Fair Value Government bonds and agency obligations $ 11,032 $ (3 ) $ 11,029 Certificates of deposit 4,658 — 4,658 Corporate bonds 4,358 (2 ) 4,356 Total available-for-sale investments $ 20,048 $ (5 ) $ 20,043

The Company - Additional Inform

The Company - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Jun. 01, 2016	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Sep. 30, 2016	Jul. 06, 2016
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Cumulative net cash flows in operating activities		$ (16,253)	$ (10,073)	$ (13,902)	$ (9,124)	$ (33,100)	$ 49,400
Accumulated deficit		$ (55,559)		$ (39,363)	$ (21,724)	$ (39,363)	$ (55,559)
Entity incorporation date		May 26, 2011
Common stock, Sale of shares		20,545,752		2,659,262	1,816,467	2,659,262	20,545,752
Proceeds from Issuance of convertible preferred stock and long-term debt		$ 53,900
Cash, cash equivalents and short-term investments		$ 56,900					$ 56,900
IPO
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
IPO, closing date		Jun. 7, 2016
Common stock, Sale of shares	7,200,000
Common stock, Share offering price	$ 7
Net proceeds from issuance of stock	$ 45,300
Underwriting discounts and commissions		$ 4,000
Offering expense		1,600
Net offering proceeds after deducting underwriting discount and commission and offering expenses		$ 51,400
Over-allotment option by underwriters
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Common stock, Share offering price								$ 7
Net proceeds from issuance of stock								$ 6,100
Common stock, Sale of shares								948,843

Significant Accounting Polici38

Significant Accounting Policies - Additional Information (Detail) $ in Thousands	May 11, 2016	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)Segment	Dec. 31, 2014USD ($)	Dec. 31, 2015USD ($)
Accounting Policies [Abstract]
Number of operating segments | Segment				1
Loss from operations		$ (15,841)	$ (12,301)	$ (17,317)	$ (9,823)	$ 14,200
Reverse split of common stock	0.4545
Reverse stock split ratio		On May 11, 2016, the Company effected a 1-for-2.2 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 convertible preferred stock.
Short-term investments maturity start period		90 days
Short-term investments maturity end period		365 days
Deferred offering costs			$ 1,900	$ 410	$ 1,750	$ 410

Net Loss Per Share - Potential

Net Loss Per Share - Potential Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share (Detail) - shares	9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	1,470,364	8,261,314	10,886,950	9,094,859
Outstanding Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share			1,261,637	1,098,486
Unvested Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share			6,485	20,688
Stock Purchase Warrant
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share			146,298	900,724
Outstanding Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	1,414,594	1,030,025
Unvested Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		10,030
Stock Purchase Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	55,770	146,298
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		7,074,961	9,472,530	7,074,961

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 262	$ 259	$ 260
Less: Accumulated depreciation	(152)	(103)	(55)
Property and equipment, net	110	156	205
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 69	$ 66	95
Estimated Useful Lives (Years)	5 years	5 years
Machinery and Equipment
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 121	$ 121	105
Estimated Useful Lives (Years)	5 years	5 years
Computer Equipment
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 27	$ 27	27
Estimated Useful Lives (Years)	3 years	3 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 45	$ 45	$ 33
Estimated Useful Lives (Years)	Lesser of Useful life or remaining lease term	Lesser of useful life or remaining lease term

Accrued Liabilities - Schedule

Accrued Liabilities - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Payables And Accruals [Abstract]
Accrued research and development	$ 790	$ 569	$ 427
Accrued bonuses	478	530	279
Accrued professional fees	78	668	178
Accrued vacation	88	64	53
Accrued interest payable	5	15
Accrued expense	117	139	220
Accrued liabilities, current	$ 1,556	$ 1,985	$ 1,157

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Detail) - USD ($)

Sep. 28, 2016

Dec. 31, 2012

Sep. 30, 2016

Sep. 30, 2015

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Sep. 30, 2017

May 31, 2015

May 15, 2015

Apr. 30, 2015

Apr. 15, 2015

Apr. 01, 2015

Apr. 30, 2013

Debt Instrument [Line Items]

Interest expense on borrowings

$ 129,000

$ 72,000

$ 100,000

Accretion of deferred closing costs

7,000

5,000

7,400

Line of credit facility, maximum borrowing capacity

$ 6,000,000

Long term debt

$ 8,000,000

8,000,000

$ 6,000,000

$ 2,000,000

$ 4,000,000

Unamortized debt discount

$ 3,000

Long term debt, maturity year

2,018

Closing costs recorded in the long-term debt

$ 24,000

Accretion of scheduled final payment

$ 224,000

$ 64,000

$ 100,000

Detachable Warrants

Debt Instrument [Line Items]

Unamortized debt discount

7,000

New Term Loan

Debt Instrument [Line Items]

Debt instrument, maturity date

Jun. 1, 2020

Long term debt

8,000,000

Debt Instrument, Payment Terms

The Company is required to pay accrued interest only through December 31, 2017 on the outstanding amount, followed by 30 equal payments of principal and accrued interest.

The Company is required to pay accrued interest only for a period of 12 months from the date of each advance, followed by 30 equal monthly payments of principal and accrued interest.

Final payment during maturity

$ 500,000

$ 300,000

Final payment during maturity, percentage

6.50%

5.50%

Repay all the amount outstanding under the original loan agreement

$ 5,300,000

New Term Loan | Scenario Forecast

Debt Instrument [Line Items]

Line of credit facility, remaining borrowing capacity

$ 7,000,000

New Term Loan | Prime Rate

Debt Instrument [Line Items]

Interest rate

0.50%

New Term Loan | Prepayment prior to September 28, 2017

Debt Instrument [Line Items]

Prepayment fee percentage of the original principal amount of the aggregate term loans

3.00%

New Term Loan | Prepayment between September 28, 2017 and May 31, 2020

Debt Instrument [Line Items]

Prepayment fee percentage of the original principal amount of the aggregate term loans

2.00%

Note Purchase Agreement

Debt Instrument [Line Items]

Interest expense on borrowings

$ 0

$ 5,000

Accretion of deferred closing costs

0

0

Loan Agreement

Debt Instrument [Line Items]

Interest expense on borrowings

$ 0

$ 2,000

Line of credit facility, maximum borrowing capacity

$ 125,000

Interest rate on loan agreement

4.25%

Long term debt

125,000

Debt instrument, maturity period

2016-02

Payment of license fees

$ 2,500,000

Unsecured Note Purchase Agreement

Debt Instrument [Line Items]

Issuance of promissory notes

$ 150,000

Line of credit facility, maximum borrowing capacity

$ 150,000

Debt instrument, interest rate

5.00%

Debt instrument, maturity date

Dec. 31, 2017

Debt instrument description

All unpaid principal, together with the balance of unpaid and accrued interest, were due and payable on demand at any time after the earlier of (i) the maturity date of December 2017, (ii) the date on which the Company has achieved sustainable profitability for a period of at least two consecutive fiscal years in accordance with generally accepted accounting principles, (iii) without the prior written consent of the lender, the date on which an equity financing of the Company in which the Company issues shares of common stock, preferred stock or other equity interests in the Company in a transaction or series of related transactions and receives an investment of cash in consideration of such issuance in the amount of not less than $7.0 million or consolidation of the Company or the sale or transfer by the Company’s stockholders of capital stock of the Company representing more than 50% of the voting power occurs or (iv) upon or after the occurrence of an event of default. The repayment acceleration provision specifically excluded the Series A-1 Preferred Stock financing that occurred in January 2013.

Capital Stock Voting Percentage

50.00%

Unsecured Note Purchase Agreement | Series A Preferred Stock

Debt Instrument [Line Items]

Promissory notes converted into preferred stock

60,291

Unsecured Note Purchase Agreement | Minimum

Debt Instrument [Line Items]

DebtInstrumentDescription

$ 7,000,000

Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

$ 6,000,000

$ 6,000,000

Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust | New Term Loan

Debt Instrument [Line Items]

Line of credit facility, maximum borrowing capacity

$ 15,000,000

Interest rate

7.00%

Debt instrument, description of variable rate basis

30-day U.S. LIBOR

Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust | New Term Loan | Prime Rate

Debt Instrument [Line Items]

Interest rate

0.50%

Long-Term Debt - Scheduled Paym

Long-Term Debt - Scheduled Payments for Loan Agreement (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 28, 2016	Dec. 31, 2015	May 15, 2015	Apr. 15, 2015
Debt Disclosure [Abstract]
Principal, 2016	$ 0
Principal, 2016			$ 1,733
Interest and Final Payment, 2016			166
Total, 2016			1,899
Principal, 2017			2,400
Principal, 2018	3,200
Principal, 2018			1,867
Principal, 2019	3,200
Principal, 2020	1,600
LongTermDebt	8,000	$ 8,000	6,000	$ 2,000	$ 4,000
Interest and Final Payment, 2016	158
Interest and Final Payment, 2017	608		96
Interest and Final Payment, 2018	476		354
Interest and Final Payment, 2019	234
Interest and Final Payment, 2020	545
Interest and Final Payment	2,021		616
Total, 2016	158
Total, 2017	608		2,496
Total, 2018	3,676		2,221
Total, 2019	3,434
Total, 2020	2,145
Total	$ 10,021		$ 6,616

Convertible Shareholder Notes44

Convertible Shareholder Notes Payable (Detail)	1 Months Ended		12 Months Ended
	Aug. 31, 2014$ / sharesshares	Apr. 30, 2014USD ($)Stockholders	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Class Of Stock [Line Items]
Interest expense			$ 330,000	$ 371,000
The Bridge Notes
Class Of Stock [Line Items]
Face amount of debt		$ 6,000,000
Issuance of promissory notes		$ 3,000,000
Debt instrument annual interest rate		7.00%
Debt instrument, maturity date		Apr. 30, 2015
Debt conversion Converted instrument Warrants options | shares	112,802
Class of warrant Exercise | $ / shares	$ 0.02
Interest expense				$ 69,000
The Bridge Notes | Series B Preferred Stock
Class Of Stock [Line Items]
Debt converted into shares of convertible preferred stock | shares	1,137,652
Executive Officer | The Bridge Notes
Class Of Stock [Line Items]
Number of stockholders | Stockholders		2
Director | The Bridge Notes
Class Of Stock [Line Items]
Number of stockholders | Stockholders		1

Schedule of Net Deferred Tax As

Schedule of Net Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current
Deferred tax asset (liability) Non-deductible accrued expenses	$ 230	$ 20
Deferred rent	3	4
Valuation allowance	(233)	(24)
Net current deferred tax asset	0	0
Non-current
Deferred tax asset (liability) Stock compensation expense	88	70
Net operating loss carryforwards	14,169	7,891
Depreciation differences	(28)	(31)
Deferred revenue	77
Deferred rent	1	4
Charitable contributions	3	3
Valuation allowance	(15,422)	(8,580)
Net non-current deferred tax asset	0	0
Federal
Non-current
Tax credits	850	447
State
Non-current
Tax credits	$ 262	$ 196

Schedule of Statutory and Effec

Schedule of Statutory and Effective Income Tax Rate Reconciliation (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
U.S. federal tax rate	34.00%	34.00%
State tax rate	4.54%	4.41%
Permanent difference and other	(1.26%)	(1.15%)
Tax credit	2.66%	4.54%
Valuation allowance	(39.94%)	(41.79%)
Total income tax provision (benefit)	0.00%	0.00%

Income Tax - Additional Informa

Income Tax - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Deferred income tax valuation allowance	$ 7,000	$ 4,200
Net deferred tax assets related to net operating loss carryforwards	$ 14,169	$ 7,891

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Convertible Preferred Stock [Line Items]
Cumulative preferred dividends		$ 5,000	$ 2,500
Proceeds from initial public offering	$ 51,377
Series A, A-1, B and C Preferred Stock
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares authorized		20,913,331
Preferred stock, dividend rate, percentage		8.00%
Series A, A-1, B and C Preferred Stock | Minimum
Convertible Preferred Stock [Line Items]
Convertible preferred stock, issued price		$ 12.51261
Proceeds from initial public offering		$ 50,000
Series A Preferred Stock
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares authorized	0	5,198,826	5,198,826
Convertible preferred stock, issued price		$ 0.78589
Liquidation preference per share		0.78589
Conversion price per share		$ 1.72896
Series A-1 Preferred Stock
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares authorized	0	4,373,481	4,373,481
Convertible preferred stock, issued price		$ 1.81320
Liquidation preference per share		1.81320
Conversion price per share		$ 3.98904
Series B Preferred Stock
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares authorized	0	6,066,345	7,413,365
Convertible preferred stock, issued price		$ 2.69783
Liquidation preference per share		2.69783
Conversion price per share		$ 5.93523
Series C Preferred Stock
Convertible Preferred Stock [Line Items]
Convertible preferred stock, shares authorized	0	5,274,679
Convertible preferred stock, issued price		$ 3.79170
Liquidation preference per share		3.79170
Conversion price per share		8.34174
Series C
Convertible Preferred Stock [Line Items]
Convertible preferred stock, issued price		$ 3.7917
Final payment during maturity, percentage		50.00%

Convertible Preferred Stock (De

Convertible Preferred Stock (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Beginning balance	$ 26,835	$ 11,871
Issuance of shares, net of issuance cost	19,954	11,501
Conversion of promissory notes and interest payable at $2.69783 per share on August 29, 2014		3,232
Accretion of stock issuance costs	525	231
Ending balance	47,314	26,835
Series A
Beginning balance	$ 4,086	$ 4,040
Beginning balance, shares	5,198,826	5,198,826
Issuance of preferred stock	0	0
Accretion of stock issuance costs		$ 46
Ending balance	$ 4,086	$ 4,086
Ending balance, shares	5,198,826	5,198,826
Series A-1 Preferred Stock
Beginning balance	$ 7,858	$ 7,831
Beginning balance, shares	4,356,931	4,356,931
Issuance of preferred stock	0	0
Accretion of stock issuance costs	$ 42	$ 27
Ending balance	$ 7,900	$ 7,858
Ending balance, shares	4,356,931	4,356,931
Series B
Beginning balance	$ 14,891
Beginning balance, shares	6,009,202
Issuance of shares, net of issuance cost		$ 11,501
Issuance of preferred stock	0	4,811,259
Conversion of promissory notes and interest payable at $2.69783 per share on August 29, 2014		$ 3,232
Conversion of promissory notes, shares		1,197,943
Accretion of stock issuance costs	$ 481	$ 158
Ending balance	$ 15,372	$ 14,891
Ending balance, shares	6,009,202	6,009,202
Series C
Issuance of shares, net of issuance cost	$ 19,954
Issuance of preferred stock	5,274,674	0
Accretion of stock issuance costs	$ 2
Ending balance	$ 19,956
Ending balance, shares	5,274,674

Convertible Preferred Stock (Pa

Convertible Preferred Stock (Parenthetical) (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Conversion of promissory notes, price per share		$ 2.69783
Series B
Issuance of shares, price per share		$ 2.69783
Issuance cost		$ 236
Series C
Issuance of shares, price per share	$ 3.7917
Issuance cost	$ 46

Common Stock - Additional Infor

Common Stock - Additional Information (Detail)	Sep. 30, 2016$ / sharesshares	Dec. 31, 2015Vote$ / sharesshares	Dec. 31, 2014$ / sharesshares	Dec. 31, 2013shares
Class Of Stock [Line Items]
Common stock, shares authorized	100,000,000	40,000,000	30,000,000
Common stock, par value | $ / shares	$ 0.001	$ 0.001	$ 0.001
Common stock, shares outstanding	20,545,752	2,659,262	1,816,467
Number of Vote | Vote		1
Unvested Restricted Stock
Class Of Stock [Line Items]
Unvested restricted stock, shares	0	6,478	20,688	229,208
Unvested Restricted Stock | Scenario, Previously Reported
Class Of Stock [Line Items]
Unvested restricted stock, shares		6,485

Stock Purchase Warrants - Addit

Stock Purchase Warrants - Additional Information (Detail) - USD ($)	1 Months Ended	9 Months Ended	12 Months Ended
	Aug. 31, 2014	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014	Jun. 06, 2016	Apr. 30, 2015	Dec. 31, 2013
Class Of Warrant Or Right [Line Items]
Common stock, shares, issued		20,545,752	2,659,262	1,816,467
Number of shares, exercised		1,326	50,980	24,803
Preferred Stock Warrants | Series A-1 Preferred Stock
Class Of Warrant Or Right [Line Items]
Exercise price of common stock upon exchange of warrants							$ 1.8132
Warrant exercisable term		10 years	10 years
Weighted average remaining life of warrants			6 years 9 months 18 days	8 years 1 month 6 days
Fair value of warrant			$ 58,000	$ 42,000
Common stock, shares, issued					3,236
Preferred Stock Warrants | Series B Preferred Stock
Class Of Warrant Or Right [Line Items]
Exercise price of common stock upon exchange of warrants						$ 3.50
Warrant exercisable term		10 years	10 years
Weighted average remaining life of warrants		8 years 6 months	9 years 3 months
Fair value of warrant		$ 300,000	$ 200,000
Preferred Stock Warrants | Series B Preferred Stock | Convertible Warrant
Class Of Warrant Or Right [Line Items]
Exercise price of common stock upon exchange of warrants						$ 7.70
Number of stock that can be purchased by each warrant						25,974
Preferred Stock Warrants | Scenario, Previously Reported | Series A-1 Preferred Stock
Class Of Warrant Or Right [Line Items]
Weighted average remaining life of warrants			7 years 1 month 6 days
Preferred Stock Warrants | Maximum | Series A-1 Preferred Stock
Class Of Warrant Or Right [Line Items]
Number of stock that can be purchased by each warrant							16,550
Preferred Stock Warrants | Maximum | Series B Preferred Stock
Class Of Warrant Or Right [Line Items]
Number of stock that can be purchased by each warrant						57,143
Convertible Stock Warrant | Convertible Promissory Note
Class Of Warrant Or Right [Line Items]
Exercise price of common stock upon exchange of warrants				$ 0.02
Weighted average remaining life of warrants			8 years 2 months 12 days	9 years 2 months 12 days
Number of shares, exercised				112,441
Convertible Stock Warrant | Amended and Restated Loan And Security Agreement
Class Of Warrant Or Right [Line Items]
Exercise price of common stock upon exchange of warrants		$ 10.74
Weighted average remaining life of warrants		10 years
Fair value of warrant		$ 300,000
Warrants expiration term		2026-09
Convertible Stock Warrant | Series B Preferred Stock
Class Of Warrant Or Right [Line Items]
Exercise price of common stock upon exchange of warrants	$ 0.02
Number of stock that can be purchased by each warrant	780,400
Exercised date of warrants	May 20, 2015
Fair value of warrant	$ 1,200,000
Convertible Stock Warrant | Series B Preferred Stock | Option Pricing Model
Class Of Warrant Or Right [Line Items]
Fair value measurements, probability weighted, expected return			60.00%
Convertible Stock Warrant | Early 2015 IPO Scenario | Series B Preferred Stock
Class Of Warrant Or Right [Line Items]
Fair value measurements, probability weighted, expected return			24.00%
Convertible Stock Warrant | Late 2015 IPO Scenario | Series B Preferred Stock
Class Of Warrant Or Right [Line Items]
Fair value measurements, probability weighted, expected return			16.00%
Convertible Stock Warrant | Maximum | Convertible Promissory Note
Class Of Warrant Or Right [Line Items]
Number of stock that can be purchased by each warrant				112,802
Convertible Stock Warrant | Maximum | Amended and Restated Loan And Security Agreement
Class Of Warrant Or Right [Line Items]
Number of stock that can be purchased by each warrant		29,796

Assumptions Utilized in Fair Va

Assumptions Utilized in Fair Value Calculation for Warrants (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]
Expected term (years)	5 years	5 years
Volatility	113.50%	109.60%
Risk-free interest rate	2.13%	2.10%
Dividend yield	0.00%	0.00%

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014	Jan. 31, 2016	Dec. 31, 2013	Nov. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense related to unvested stock options	$ 3,100,000	$ 3,000,000
Expected to be recognized over a weighted average period	1 year 6 months	1 year 8 months 12 days
Weighted average remaining contractual life of all outstanding options		8 years 4 months 24 days
Estimated fair market value per share of common stock		$ 8.12
Option to purchase common stock shares outstanding	1,414,594	1,261,638	1,098,486		770,062
Weighted Average Exercise Price	$ 2.90	$ 2.41	$ 1.39		$ 0.34
Number of shares grants	174,736	289,619	376,126
Unvested Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense		$ 0	$ 0
2016 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares common stock reserved for issuance				1,818,182
Share based compensation arrangement description	The number of shares of common stock reserved for issuance under the 2016 Plan will automatically increase on January 1 each year, for a period of ten years, from January 1, 2017 through January 1, 2026, by 4% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares as may be determined by the Company’s board of directors.
Annual increase of common stock reserved for issuance	4.00%
Option to purchase common stock shares outstanding	157,500
Weighted Average Exercise Price	$ 6.64
Shares available for future grant	1,660,682
2011 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares common stock reserved for issuance						1,517,625
Option to purchase common stock shares outstanding	1,239,858
Weighted Average Exercise Price	$ 2.35
Number of shares grants	0
2011 Stock Incentive Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based awards vested period		1 year
2011 Stock Incentive Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based awards vested period		5 years
Share-based awards, expiration period		10 years

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Share-based Compensation Expense (Detail) - USD ($) $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 776	$ 502	$ 705	$ 427
Outstanding Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense			705	283
Unvested Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense				144
Research and Development
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	375	229	327	218
Research and Development | Outstanding Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense			327	91
Research and Development | Unvested Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense				127
General and Administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense	$ 401	$ 273	378	209
General and Administrative | Outstanding Stock Options
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense			$ 378	192
General and Administrative | Unvested Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share-based compensation expense				$ 17

Share-Based Compensation - Weig

Share-Based Compensation - Weighted Average Assumptions Used in Fair Value Calculation for Underlying Common Stock (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Expected term (years)	7 years	7 years
Expected stock price volatility	86.63%	85.64%
Risk-free interest rate	2.09%	1.99%
Expected dividend yield	0.00%	0.00%

Share-Based Compensation - Su57

Share-Based Compensation - Summary of Activity Related to Stock Options (Detail) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, Options Outstanding Beginning balance	1,261,638	1,098,486	770,062
Number of shares, Granted	174,736	289,619	376,126
Number of shares, Exercised	(1,326)	(50,980)	(24,803)
Number of shares, Cancelled/Forfeited	(20,454)	(75,488)	(22,899)
Number of shares, Options Outstanding Ending balance	1,414,594	1,261,638	1,098,486
Number of Shares, Options exercisable	686,439	500,797
Weighted Average Exercise Price, Options outstanding, Beginning balance	$ 2.41	$ 1.39	$ 0.34
Weighted Average Exercise Price, Granted	6.79	5.68	3.38
Weighted Average Exercise Price, Exercised	0.40	0.27	0.17
Weighted Average Exercise Price, Cancelled/Forfeited	6.03	1.67	0.15
Weighted Average Exercise Price, Options outstanding, Ending balance	2.90	2.41	$ 1.39
Weighted Average Exercise Price, Options exercisable	$ 1.22	$ 0.92
Scenario, Previously Reported
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, Options Outstanding Beginning balance	1,261,637
Number of shares, Options Outstanding Ending balance		1,261,637
Weighted Average Exercise Price, Options outstanding, Beginning balance	$ 2.40
Weighted Average Exercise Price, Options outstanding, Ending balance		$ 2.40

Share-Based Compensation - Ad58

Share-Based Compensation - Additional Information about the Stock Option Outstanding and Exercisable (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Sep. 30, 2016	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	1,261,638	1,414,594	1,098,486	770,062
Weighted Average Exercise Price	$ 2.41	$ 2.90	$ 1.39	$ 0.34
Aggregate Intrinsic Value	$ 7,210
Options Exercisable	500,797	686,439
Weighted Average Exercise Price	$ 0.92	$ 1.22
Aggregate Intrinsic Value	$ 3,606
Scenario, Previously Reported
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	1,261,637
Weighted Average Exercise Price	$ 2.40
0.02
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 0.02
Options Outstanding	11,363
Average Remaining Contractual Life (Years)	5 years 10 months 24 days
Options Exercisable	11,363
0.15
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 0.15
Options Outstanding	72,987
Average Remaining Contractual Life (Years)	6 years 4 months 24 days
Options Exercisable	67,510
0.4
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 0.40
Options Outstanding	544,493
Average Remaining Contractual Life (Years)	7 years 7 months 6 days
Options Exercisable	329,131
3.08
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 3.08
Options Outstanding	31,818
Average Remaining Contractual Life (Years)	8 years 7 months 6 days
Options Exercisable	11,267
3.41
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 3.41
Options Outstanding	311,357
Average Remaining Contractual Life (Years)	9 years
Options Exercisable	79,254
5.57
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 5.57
Options Outstanding	232,802
Average Remaining Contractual Life (Years)	9 years 10 months 24 days
6.16
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price	$ 6.16
Options Outstanding	56,817
Average Remaining Contractual Life (Years)	9 years 6 months
Options Exercisable	2,272

Summary of the Unvested Restric

Summary of the Unvested Restricted Stock (Detail) - Unvested Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Number of Shares
Number of Shares, Unvested, beginning balance	20,688	229,208
Number of Shares, Vested	(14,203)	(208,520)
Number of Shares, Unvested at December 31, 2015	6,478	20,688
Weighted Average Grant Date Fair Value
Weighted Average Exercise Price, Unvested, beginning balance	$ 0.57	$ 0.51
Weighted Average Exercise Price, Vested	0.55	0.40
Weighted Average Exercise Price, Unvested, ending balance	$ 0.57	$ 0.57
Scenario, Previously Reported
Number of Shares
Number of Shares, Unvested at December 31, 2015	6,485

Commitment and Contingencies -

Commitment and Contingencies - Additional Information (Detail) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Non-cancelable operating leases, expiration date	2017-03		2017-03
Rent expense, net of sublease income	$ 61,000	$ 61,000	$ 150,000	$ 198,000

Commitment and Contingencies 61

Commitment and Contingencies - Future Minimum Commitments Due Under Non-Cancelable Operating Leases (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Asset Purchase Agreement And Related License Agreement [Abstract]
2,016		$ 90
2,016	$ 23
2,017	23	23
Total minimum lease payments	$ 46	$ 113

License Agreements - Additional

License Agreements - Additional Information (Detail) - USD ($)	Apr. 27, 2015	Aug. 31, 2014	Dec. 31, 2012	Sep. 30, 2016	Mar. 31, 2016	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014	Apr. 30, 2015
Research And Development Arrangement Contract To Perform For Others [Line Items]
License revenue						$ 515,000
NovaMedica
Research And Development Arrangement Contract To Perform For Others [Line Items]
Milestone payment		$ 12,700,000
License revenue				$ 5,000		$ 15,000
Patent expirations period						2,027
Spark Therapeutics, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
License revenue	$ 500,000				$ 500,000
Upfront, non-refundable payment									$ 500,000
Emory/GTRC
Research And Development Arrangement Contract To Perform For Others [Line Items]
License payment			$ 30,000				$ 0	$ 0
Milestone payment			$ 35,000
Annual license maintenance fee							25,000
Increase in minimum annual royalty							100,000
Rusnano MedInvest LLC
Research And Development Arrangement Contract To Perform For Others [Line Items]
Percentage of voting securities owned subsidiary		11.00%
Upfront payment | NovaMedica
Research And Development Arrangement Contract To Perform For Others [Line Items]
Deferred revenue		$ 200,000			$ 200,000		200,000	$ 200,000
Minimum | Emory/GTRC
Research And Development Arrangement Contract To Perform For Others [Line Items]
Annual royalties expense							$ 15,000
License Agreement Terms | Spark Therapeutics, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Research and development agreement, description						Spark could exercise its option to license the IP by paying an additional $2.0 million, or could elect to initiate a second Option Period during which the Company and Spark would conduct further studies specified in the Spark Agreement. If Spark elected to initiate the second Option Period, Spark would be required to pay the Company $1.0 million. If Spark exercised its option to license the IP during the second Option Period, then Spark would be required to pay the Company an additional $3.0 million.
development and commercialization milestones | Spark Therapeutics, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue Recognition, Milestone Method, Additional Revenue Potential to be Earned	13,500,000
Specified annual net sales milestones | Spark Therapeutics, Inc.
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue Recognition, Milestone Method, Additional Revenue Potential to be Earned	$ 12,000,000

Collaborative Agreement - Addit

Collaborative Agreement - Additional Information (Detail) - USD ($)	9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development costs	$ 12,484,000	$ 6,964,000	$ 10,762,000	$ 6,692,000
Collaborative Research Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development costs	$ 85,000	$ 124,000	$ 98,000	$ 145,000

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Financial Assets:
Total financial assets	$ 56,919
Stock Purchase Warrants
Financial Liabilities:
Stock purchase warrants	251	$ 258	$ 42
Corporate Bonds
Financial Assets:
Total financial assets	4,356
Cash and Money Markets
Financial Assets:
Total financial assets	35,666
Certificates of Deposit
Financial Assets:
Total financial assets	5,868
Government Bonds
Financial Assets:
Total financial assets	2,499
Agency Obligations
Financial Assets:
Total financial assets	8,530
Money Markets
Financial Assets:
Total financial assets		20,076	7,951
Level 1
Financial Assets:
Total financial assets	44,033
Level 1 | Cash and Money Markets
Financial Assets:
Total financial assets	35,666
Level 1 | Certificates of Deposit
Financial Assets:
Total financial assets	5,868
Level 1 | Government Bonds
Financial Assets:
Total financial assets	2,499
Level 1 | Money Markets
Financial Assets:
Total financial assets		20,076	7,951
Level 2
Financial Assets:
Total financial assets	12,886
Level 2 | Corporate Bonds
Financial Assets:
Total financial assets	4,356
Level 2 | Agency Obligations
Financial Assets:
Total financial assets	8,530
Level 3 | Stock Purchase Warrants
Financial Liabilities:
Stock purchase warrants	$ 251	$ 258	$ 42

Fair Value Measurements - Sum65

Fair Value Measurements - Summarizes the Changes in Fair Value of the Level 3 Liability, Stock Purchase Warrants (Detail) - Stock Purchase Warrants (Detail) - Stock Purchase Warrants - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Dec. 31, 2014
Stock purchase warrants
Balance at beginning of period	$ 258	$ 42	$ 24
Issuance of stock purchase warrants		164
Exercise of stock purchase warrants	(23)
Net increase in fair value remeasurement	16	52	18
Balance at end of period	$ 251	$ 258	$ 42

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail)	May 11, 2016	Dec. 02, 2016USD ($)ft²	Sep. 30, 2016
Subsequent Event [Line Items]
Reverse stock split ratio			On May 11, 2016, the Company effected a 1-for-2.2 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 convertible preferred stock.
Reverse split of common stock	0.4545
Subsequent Event | GEORGIA
Subsequent Event [Line Items]
Area of office leased | ft²		20,000
Initial annual base rent		$ 421,740
Percentage of increase per year		3.00%
Minimum monthly lease payments		$ 35,145

Convertible Debt (Detail)

Convertible Debt (Detail) - $ / shares	Sep. 30, 2016	Jun. 01, 2016	Dec. 31, 2015
Class Of Stock [Line Items]
Preferred stock convertible into common stock		9,614,159
Preferred stock, shares authorized	10,000,000		0
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0
Series A, A-1, B and C Preferred Stock
Class Of Stock [Line Items]
Convertible preferred stock, shares authorized			20,913,331
Convertible preferred stock, par value			$ 0.001
Convertible Preferred Stock | IPO
Class Of Stock [Line Items]
Convertible preferred stock, shares issued		20,839,633
Convertible preferred stock, shares outstanding		20,839,633

Available-for Sale Securities -

Available-for Sale Securities - Summary of Company's Available-For-Sale Investments (Detail) $ in Thousands	Sep. 30, 2016USD ($)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 20,048
Unrealized Loss	(5)
Fair Value	20,043
Government Bonds and Agency Obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	11,032
Unrealized Loss	(3)
Fair Value	11,029
Certificates of Deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,658
Fair Value	4,658
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,358
Unrealized Loss	(2)
Fair Value	$ 4,356

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2016
Fair Value Disclosures [Abstract]
Short-term investments maturity start period	90 days
Short-term investments maturity end period	365 days