Clearside Biomedical (CLSD) 10-K 16 Mar 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2016	Mar. 10, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Entity Registrant Name	Clearside Biomedical, Inc.
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	CLSD
Document Type	10-K
Entity Central Index Key	1,539,029
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		25,286,016
Entity Public Float			$ 44,137,000

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 34,824	$ 20,283
Short-term investments	48,807
Prepaid expenses	396	159
Other current assets	290	40
Total current assets	84,317	20,482
Property and equipment, net	94	156
Deferred offering costs		410
Restricted cash	360
Other assets	42	7
Total assets	84,813	21,055
Current liabilities:
Accounts payable	2,594	1,469
Accrued liabilities	2,791	1,985
Current portion of long-term debt		1,733
Other current liabilities	23	9
Total current liabilities	5,408	5,196
Deferred revenue	160	700
Long-term debt	7,586	4,243
Other non-current liabilities		261
Total liabilities	13,154	10,400
Commitments and contingencies
Convertible preferred stock:
Total convertible preferred stock		47,314
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value; 10,000,000 shares authorized and no shares issued at December 31, 2016; no shares authorized or issued at December 31, 2015
Common stock, $0.001 par value; 100,000,000 shares authorized and 24,573,033 shares issued and outstanding at December 31, 2016; 40,000,000 shares authorized and 2,659,262 shares issued and outstanding at December 31, 2015	25	3
Additional paid-in capital	136,892	2,701
Accumulated deficit	(65,245)	(39,363)
Accumulated other comprehensive loss	(13)
Total stockholders’ equity (deficit)	71,659	(36,659)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 84,813	21,055
Series A Preferred Stock
Convertible preferred stock:
Total convertible preferred stock		4,086
Series A-1 Preferred Stock
Convertible preferred stock:
Total convertible preferred stock		7,900
Series B Preferred Stock
Convertible preferred stock:
Total convertible preferred stock		15,372
Series C Preferred Stock
Convertible preferred stock:
Total convertible preferred stock		$ 19,956

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
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
Common stock, shares authorized	100,000,000	40,000,000
Common stock, shares, issued	24,573,033	2,659,262
Common stock, shares outstanding	24,573,033	2,659,262
Series A Preferred Stock
Convertible preferred stock, par value	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	5,198,826
Convertible preferred stock, shares issued	0	5,198,826
Convertible preferred stock, shares outstanding	0	5,198,826
Convertible preferred stock, liquidation preference	$ 0	$ 4,086
Series A-1 Preferred Stock
Convertible preferred stock, par value	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	4,373,481
Convertible preferred stock, shares issued	0	4,356,931
Convertible preferred stock, shares outstanding	0	4,356,931
Convertible preferred stock, liquidation preference	$ 0	$ 7,900
Series B Preferred Stock
Convertible preferred stock, par value	$ 0.001	$ 0.001
Convertible preferred stock, shares authorized	0	6,066,345
Convertible preferred stock, shares issued	0	6,009,202
Convertible preferred stock, shares outstanding	0	6,009,202
Convertible preferred stock, liquidation preference	$ 0	$ 16,212
Series C Preferred Stock
Convertible preferred stock, par value	$ 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	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
License revenue	$ 520
Operating expenses:
Research and development	19,455	$ 10,762	$ 6,692
General and administrative	6,263	6,555	3,131
Total operating expenses	25,718	17,317	9,823
Loss from operations	(25,198)	(17,317)	(9,823)
Other expense	(684)	(322)	(366)
Net loss	$ (25,882)	$ (17,639)	$ (10,189)
Net loss per share of common stock — basic and diluted	$ (1.97)	$ (7.54)	$ (5.86)
Weighted average shares outstanding — basic and diluted	13,111,067	2,338,950	1,738,660
Net loss	$ (25,882)	$ (17,639)	$ (10,189)
Unrealized loss on available-for-sale investments	(13)
Comprehensive loss	$ (25,895)	$ (17,639)	$ (10,189)

Statement of Stockholders' Equi

Statement of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Common Stock	Additional Paid-In-Capital	Additional Paid-In-CapitalRedeemable Convertible Preferred Stock	Accumulated Deficit	Accumulated Other Comprehensive Loss
Beginning balance at Dec. 31, 2013	$ (10,737)		$ 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
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
Stock Issued During Period, Value, Conversion of Convertible Securities	3,232
Exercise of stock options	14			14
Exercise of stock options, shares			50,980
Vesting of restricted stock, shares			14,203
Issuance of common stock upon exercise of warrants	(1)		$ 1	(2)
Issuance of common stock upon exercise of warrants, Shares			777,612
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	31			31
Exercise of stock options, shares			10,724
Vesting of restricted stock, shares			6,485
Issuance of common stock upon exercise of warrants	410			410
Issuance of common stock upon exercise of warrants, Shares			133,560
Issuance of common stock for initial public offering	51,377		$ 8	51,369
Issuance of common stock for initial public offering, Shares			8,148,843
Issuance of common stock for follow-on offering	33,459		$ 4	33,455
Issuance of common stock for follow-on offering, Shares			4,000,000
Conversion of preferred stock to common stock	48,198		$ 10	48,188
Conversion of preferred stock to common stock, Shares			9,614,159
Issuance of warrants to purchase common stock	308			308
Accretion of stock issuance costs		$ (884)			$ (884)
Share-based compensation expense	1,314			1,314
Net loss	(25,882)					(25,882)
Other comprehensive loss	(13)						$ (13)
Ending balance at Dec. 31, 2016	$ 71,659		$ 25	$ 136,892		$ (65,245)	$ (13)
Ending balance, shares at Dec. 31, 2016			24,573,033

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Operating activities
Net loss	$ (25,882)	$ (17,639)	$ (10,189)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	65	60	33
Share-based compensation expense	1,314	705	427
Non-cash interest expense	283	104	82
Accretion of debt discount	108	60	277
Change in fair value of warrant liability	156	52	18
Amortization and accretion on available-for-sale investments, net	(43)
Loss on sale of fixed assets		15
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(487)	(145)	54
Other assets	882	1,763	(1,154)
Accounts payable and accrued liabilities	1,424	632	1,137
Deferred revenue	(520)	500	200
Deferred rent	(9)	(9)	(9)
Net cash used in operating activities	(22,709)	(13,902)	(9,124)
Investing activities
Purchase of available-for-sale investments	(54,485)
Maturities of available-for-sale-investments	5,708
Change in restricted cash	(360)
Acquisition of property and equipment	(3)	(32)	(140)
Proceeds from the sale of fixed assets		4
Net cash used in investing activities	(49,140)	(28)	(140)
Financing activities
Proceeds from initial public offering, net of issuance costs	51,376
Proceeds from follow-on offering, net of issuance costs	33,456
Proceeds from issuance of long-term debt	7,857	5,976	3,000
Principal payments made on long-term debt	(6,330)		(125)
Proceeds from exercise of stock options	31	14	5
Net cash provided by financing activities	86,390	25,944	15,624
Net increase in cash and cash equivalents	14,541	12,014	6,360
Cash and cash equivalents, beginning of period	20,283	8,269	1,909
Cash and cash equivalents, end of period	34,824	20,283	8,269
Supplemental disclosure
Interest paid	250	100	7
Supplemental disclosure of noncash investing and financing activities
Conversion of convertible preferred stock to common stock	48,198
Conversion of stockholder loan, promissory note and accrued interest			3,232
Reclassification of deferred initial public offering costs	1,597
Issuance of warrants to purchase common stock	308		1,506
Issuance of warrant to purchase Series B preferred stock		164
Accretion of redeemable convertible preferred stock to redemption value	884	525	231
Unpaid initial public offering costs in accounts payable and accrued expenses	$ 507	410	602
Series C Preferred Stock
Financing activities
Proceeds from the issuance of Preferred Stock, net of issuance costs		$ 19,954
Series B Preferred Stock
Financing activities
Proceeds from the issuance of Preferred Stock, net of issuance costs			$ 12,744

The Company

The Company	12 Months Ended
	Dec. 31, 2016
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 (“SCS”) 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. On December 9, 2016, the Company’s registration statement on Form S-1 relating to its follow-on public offering of its common stock was declared effective by the SEC. The follow-on public offering closed on December 14, 2016 and the Company sold 4,000,000 share of common stock at a price to the public of $9.00 per share, for net proceeds of $33.4 million. On December 30, 2016, the underwriters of the IPO exercised their option to purchase additional shares and on January 6, 2017, the Company sold 600,000 additional shares of common stock at a price to the public of $9.00 per share, for net proceeds of $5.1 million. The Company paid to the underwriters underwriting discounts and commissions of $2.5 million in connection with the follow-on public offering, including the underwriters’ exercise of their option to purchase additional shares, and incurred expenses of $0.4 million in connection with the follow-on public offering. Prior to the IPO and the follow-on offering, 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 $83.6 million as of December 31, 2016 and cumulative net cash flows used in operating activities of $55.8 million and cumulative net losses of $65.2 million through December 31, 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 the date of issuance of these financial statements will be sufficient to fund its operations for at least the next 18 months from that date.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
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”). 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, clinical trial accruals, 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. 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. 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 certain 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 $23.3 million for the period from May 26, 2011 (inception) to December 31, 2016. 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. 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 liabilities 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 based on the estimated fair value of the award at the grant date. 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 loss until realized. In addition, the Company evaluates the short-investments with unrealized losses to determine whether such losses are other-than-temporary. Restricted Cash The Company is required to maintain a stand-by letter of credit as a security deposit for its new facility lease in Alpharetta, Georgia. The Company’s bank requires the Company to maintain a restricted cash balance to serve as collateral for the letter of credit issued to the landlord by the bank. As of December 31, 2016, the restricted cash balance was invested in a commercial money market account. 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 Accounting Pronouncements Recently Adopted In August 2014, the Financial Accounting Standards Board ("FASB") Accounting Standards Update (“ Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern In November 2015, the FASB issued ASU 2015-17, Income Taxes (Topic 740) Balance Sheet Classification of Deferred Taxes. The guidance simplifies the presentation of deferred income taxes. The guidance eliminates the current requirement to present deferred tax assets and liabilities as current and noncurrent in a classified balance sheet and now requires entities to classify all deferred tax assets and liabilities as noncurrent. In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718). Recent Accounting Pronouncements Not Yet Adopted In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers In February 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842), In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows Classification of Certain Cash Receipts and Cash Payments In November 2016, the FASB issued ASU 2016-18, Restricted Cash,

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2016
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) December31, 2016 2015 Furniture and fixtures 5 $ 69 $ 66 Machinery and equipment 5 121 121 Computer equipment 3 27 27 Leasehold improvements Lesser of useful life remaining lease term 45 45 262 259 Less: Accumulated depreciation (168 ) (103 ) $ 94 $ 156

Accrued Liabilities

Accrued Liabilities	12 Months Ended
	Dec. 31, 2016
Payables And Accruals [Abstract]
Accrued Liabilities	4. Accrued Liabilities Accrued liabilities consisted of the following (in thousands): December 2016 2015 Accrued research and development $ 1,153 $ 569 Accrued bonuses 870 530 Accrued professional fees 410 668 Accrued vacation 72 64 Accrued interest payable 52 15 Accrued expense 234 139 $ 2,791 $ 1,985

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Long-Term Debt	5. Long-Term Debt Loan and Security Agreements In April 2015, the Company entered into a loan agreement (the “original loan agreement”) with Silicon Valley Bank (“SVB”) for borrowings up to $6.0 million, with a floating interest rate equal to the Wall Street Journal’s prime rate minus 0.50%. Under the terms of the original loan agreement, 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 was 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, was due at maturity of the loan in 2018 and was being accreted in long-term debt over the life of the loan. Closing costs of $24,000 were recorded in long-term debt and were also being accreted over the life of the loan. In September 2016, the Company entered into an amended and restated loan and security agreement (the “loan agreement”) with 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 original loan agreement. 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%. 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 for its drug candidate CLS-TA for the treatment of non-infectious 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 and the loan agreement was $287,000 and $115,000 for the years ended December 31, 2016 and 2015, respectively. Accretion of the scheduled final payment under the original loan agreement and the loan agreement was $283,000 and $101,000 for the years ended December 31, 2016 and 2015, respectively. Accretion of the deferred closing costs under the original loan agreement and the loan agreement was $17,000 and $7,400 for the years ended December 31, 2016 and 2015, respectively. As of December 31, 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 Total 2017 $ — $ 608 $ 608 2018 3,200 476 3,676 2019 3,200 234 3,434 2020 1,600 545 2,145 $ 8,000 $ 1,863 $ 9,863

Convertible Shareholder Notes P

Convertible Shareholder Notes Payable	12 Months Ended
	Dec. 31, 2016
Equity [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 which occurred in August 2014, 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 the 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. 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.

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2016
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock	7. Convertible Preferred Stock 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, 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. The following table summarizes the activity of convertible preferred stock (in thousands, except per share amounts): Total Series A Series A-1 Series B Series C Convertible Preferred Stock Preferred Stock Preferred Stock Preferred Stock Preferred Shares Amount Shares Amount Shares Amount Shares Amount Stock 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 note and interest payable at $2.69783 per share on August 29, 2014 — — — — 1,197,943 3,232 — — 3,232 Accretion of redeemable convertible preferred stock to redemption value — 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 redeemable convertible preferred stock to redemption value — — — 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 Accretion of redeemable convertible preferred stock to redemption value — — — — — 840 — 44 884 Conversion of preferred stock to common stock at closing of IPO (5,198,826 ) (4,086 ) (4,356,931 ) (7,900 ) (6,009,202 ) (16,212 ) (5,274,674 ) (20,000 ) (48,198 ) Balance at December 31, 2016 — $ — — $ — — $ — — $ — $ — As of December 31, 2016, there were 10,000,000 shares of preferred stock authorized, none of which were issued and outstanding.

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Common Stock	8. 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 December 31, 2016 and 2015, there were 24,573,033 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 December 31, 2016.

Stock Purchase Warrants

Stock Purchase Warrants	12 Months Ended
	Dec. 31, 2016
Stock Purchase Warrants [Abstract]
Stock Purchase Warrants	9. 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, in connection with the IPO, resulting in the issuance of 3,236 shares of common stock. In April 2015, in connection with the original 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 December 31, 2015 and had a weighted average remaining life of 9.25 years and a fair value of $0.2 million. This warrant was net exercised on October 12, 2016, resulting in the issuance of 17,883 shares of common stock. 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 loan 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 .

Share-Based Compensation

Share-Based Compensation	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	10. Share-Based Compensation Stock Options 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 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 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 December 31, 2016, under the 2016 Plan, options to purchase 1,035,200 shares of the Company’s common stock were outstanding at a weighted average price of $9.72 per share and 782,982 shares remained available for future grant. As of January 1, 2017, the number of shares of common stock that may be issued under the 2016 Plan was automatically increased by 982,921 shares, representing 4% of the total number of shares of common stock outstanding on January 1, 2017, increasing the number of shares of common stock available for issuance under the 2016 Plan to 1,765,903 shares. 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 December 31, 2016, options to purchase 1,191,139 shares of the Company’s common stock were outstanding under the 2011 Plan at a weighted average exercise price of $2.32 per share. The Company has granted stock option awards to employees, directors and consultants. The total share-based compensation expense recognized is reflected in the statements of operations as follows (in thousands): Year Ended December 31, 2016 2015 2014 Research and development $ 539 $ 327 $ 218 General and administrative 775 378 209 Total $ 1,314 $ 705 $ 427 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, 2016, 2015 and 2014. Year Ended December 31, 2016 2015 2014 Expected term (years) 7.00 7.00 7.00 Expected stock price volatility 97.45 % 86.63 % 85.64 % Risk-free interest rate 2.20 % 2.09 % 1.99 % Expected dividend yield 0.00 % 0.00 % 0.00 % Expected term (in years): The Company utilized the guidance set forth in ASC 718 to determine the expected term of options. The Company utilized the simplified method as prescribed by ASC 718, as the Company does not have sufficient historical exercise and post-vesting termination data to provide a reasonable basis upon which to estimate the expected term of stock options granted to employees. Risk-free interest rate : The risk-free interest rate is based on the yields of U.S. Treasury securities with maturities similar to the expected time to a possible liquidity event. Expected dividend yield : The Company has not paid and does not anticipate paying any dividends in the foreseeable future. Expected stock price volatility : The volatility assumption is based on the historical volatilities of the stock of several public entities that are similar to the Company, as the Company does not have sufficient historical transactions in its own shares on which to base expected volatility. A similar peer group of companies was utilized for 2016 and 2015. Forfeitures. Forfeitures are estimated such that the Company only recognizes expense for the shares expected to vest, and adjustments are made if actual forfeitures differ from those estimates. The Company has estimated its forfeiture rate to be zero for the periods presented and any expense true-ups for terminated employees have been immaterial. The following table summarizes the activity related to stock options during the year ended December 31, 2016: Weighted Number of Average Shares Exercise Price Options outstanding at January 1, 2016 1,261,638 $ 2.41 Granted 1,052,436 9.70 Exercised (10,724 ) 2.84 Cancelled/Forfeited (59,775 ) 4.02 Options outstanding at December 31, 2016 2,243,575 5.78 Options exercisable at December 31, 2015 500,797 0.92 Options exercisable at December 31, 2016 789,120 1.55 The following table provides additional information about the Company’s stock options that were outstanding and exercisable at December 31, 2016 (aggregate intrinsic values in thousands): Weighted Weighted Average Weighted Average Aggregate Remaining Average Aggregate Exercise Options Exercise Intrinsic Contractual Options Exercise Intrinsic Price Outstanding Price Value Life (Years) Exercisable Price Value $0.02 - $0.40 604,897 6.4 538,368 $3.08 - $6.49 706,242 8.5 245,486 $7.14 - $8.90 829,936 9.9 5,266 $20.16 - $20.84 102,500 10.0 — 2,243,575 $ 5.78 $ 7,086 789,120 $ 1.55 $ 5,830 As of December 31, 2016, the Company had $9.9 million of unrecognized compensation expense related to unvested stock options, which is expected to be recognized over a weighted average period of 1.9 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, 2016 was $8.94 which was the closing sale price of the Company’s common stock on the Nasdaq Global Market on that date. Employee Stock Purchase Plan In January 2016, the Company’s board of directors adopted and approved the Clearside Biomedical, Inc. 2016 Employee Stock Purchase Plan (the “2016 ESPP”) which became effective on June 1, 2016. The 2016 ESPP permits employees to purchase shares of the Company’s common stock through payroll deductions up to 15% of their earnings. The Company reserved 181,818 shares of common stock for issuance under the 2016 ESPP. Additionally, the number of shares reserved for issuance under the 2016 ESPP will automatically increase for a period of ten years, from January 1, 2017 through January 1, 2026, by the lesser of (i) 1% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, (ii) 454,545 shares of common stock or (iii) a lesser number of shares as may be determined by the Company’s board of directors. As of January 1, 2017, the number of shares of common stock that may be issued under the 2016 ESPP was automatically increased by 245,730 shares, representing 1% of the total number of shares of common stock outstanding on January 1, 2017, increasing the number of shares of common stock available for issuance under the 2016 ESPP to 427,548 shares. The first offering period for the 2016 ESPP commenced on January 1, 2017.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	11. 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, 2016 2015 2014 Current Deferred tax asset (liability) Non-deductible accrued expenses $ 358 $ 230 $ 20 Deferred rent 1 3 4 Deferred revenue 8 — — Valuation allowance (367 ) (233 ) (24 ) Net current deferred tax asset $ — $ — $ — Non-current Deferred tax asset (liability) Net operating loss carryforwards $ 23,391 $ 14,119 $ 7,891 Stock compensation expense 101 88 70 Depreciation differences (13 ) (28 ) (31 ) Federal tax credits 1,232 850 447 State tax credits 301 262 196 Deferred revenue 61 77 0 Deferred rent — 1 4 Charitable contributions 6 3 3 Valuation allowance (25,079 ) (15,372 ) (8,580 ) 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, 2016 2015 2014 U.S. federal tax rate 34.00 % 34.00 % 34.00 % State tax rate 3.79 4.54 4.41 Permanent difference and other (1.98 ) (1.26 ) (1.15 ) Tax credit 1.62 2.66 4.54 Valuation allowance (37.43 ) (39.94 ) (41.80 ) 0.00 % 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 $9.7 million, $7.0 million and $ 4.2 million for the years ended December 31, 2016, 2015 and 2014, respectively. As of December 31, 2016, the Company had net deferred tax assets primarily related to net operating loss carryforwards of $23.3 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.

Commitment and Contingencies

Commitment and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	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. In November 2016, the Company signed a new office lease agreement to lease approximately 20,000 square feet of office space in Alpharetta, Georgia. The lease agreement is for a six and one-half year term with a renewal option for one additional five-year term. Rental payments are $35,145 per month subject to an increase of 3% per year. In addition, the lease agreement requires payment of the pro-rata share of the annual operating expenses associated with the premises. The Company expects to relocate its corporate headquarters into this new space in March 2017. Minimum lease payments were as follows at December 31, 2016 (in thousands): 2017 $ 128 2018 431 2019 444 2020 458 2021 472 Thereafter 860 Total minimum lease payments $ 2,793 Rent expense, net of sublease income, was $81,000, $150,000 and $198,000 for the years ended December 31, 2016, 2015 and 2014, respectively. 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.

License Agreements

License Agreements	12 Months Ended
	Dec. 31, 2016
License Agreements [Abstract]
License Agreements	13. 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 SCS. 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 $20,000 of license revenue during year ended December 31, 2016 for this license agreement. NovaMedica is jointly owned by Rusnano MedInvest LLC (“Rusnano MedInvest”) and Domain Russia Investments Limited. RMI Investments, which beneficially owned approximately 6% of the Company’s voting securities as of December 31, 2016, 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 SCS 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 Spark 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 the Spark Agreement.

Collaborative Agreement

Collaborative Agreement	12 Months Ended
	Dec. 31, 2016
Collaborative Agreement [Abstract]
Collaborative Agreement	14. 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 $83,000, $145,000 and $98,000 for the years ended December 31, 2016, 2015 and 2014, respectively.

Available-for Sale Investments

Available-for Sale Investments	12 Months Ended
	Dec. 31, 2016
Investments Debt And Equity Securities [Abstract]
Available-for Sale Investments	15. Available-for-Sale Investments The following table summarizes the Company’s available-for-sale investments as of December 31, 2016 (in thousands): December 31, 2016 Amortized Unrealized Fair Cost Loss Value Government bonds and agency obligations $ 23,213 $ (8 ) $ 23,205 Commercial paper 12,461 — 12,461 Certificates of deposit 6,579 — 6,579 Corporate bonds 6,567 (5 ) 6,562 Total available-for-sale investments $ 48,820 $ (13 ) $ 48,807

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	16. 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, 2016 and 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, government bonds, other current assets and accounts payable approximate their respective carrying values due to the short term nature of these instruments and are classified as Level 1 in the fair hierarchy. 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, commercial paper 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 years ended December 31, 2016 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, 2016 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Cash and money markets $ 29,928 $ — $ — $ 29,928 Restricted cash money market 360 — — 360 Government bonds 19,027 — — 19,027 Certificates of deposit — 6,579 — 6,579 Agency obligations — 4,179 — 4,179 Corporate bonds — 7,262 — 7,262 Commercial paper — 16,656 — 16,656 Total financial assets $ 49,315 $ 34,676 $ — $ 83,991 December 31, 2015 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Cash and money markets $ 20,283 $ — $ — $ 20,283 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. 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. Changes in the fair value of the stock purchase warrants were recorded in other 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 2016 2015 Stock purchase warrants Balance at beginning of period $ 258 $ 42 Issuance of stock purchase warrants — 164 Exercise of stock purchase warrants (414 ) — Net increase in fair value remeasurement 156 52 Balance at end of period $ — $ 258

Net Loss per Share

Net Loss per Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Net Loss Per Share	17. 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: Year Ended December 31, 2016 2015 2014 Convertible preferred stock — 9,472,530 7,074,961 Outstanding stock options 2,243,575 1,261,637 1,098,486 Unvested restricted stock — 6,485 20,688 Stock purchase warrants 29,796 146,298 900,724 2,273,371 10,886,950 9,094,859

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Quarterly Financial Information (Unaudited)	18. Quarterly Financial Information (unaudited) Summarized quarterly financial information for each of the years ended December 31, 2016 and 2015 are as follows (in thousands except per share data): Quarter Ended March 31, 2016 June 30, 2016 September 30, 2016 December 31, 2016 Operating expenses $ (5,862 ) $ (5,183 ) $ (5,311 ) $ (9,362 ) Net loss $ (5,449 ) $ (5,102 ) $ (5,645 ) $ (9,686 ) Net loss per share of common stock — basic and diluted $ (2.05 ) $ (0.62 ) $ (0.28 ) $ (0.45 ) Quarter Ended March 31, 2015 June 30, 2015 September 30, 2015 December 31, 2015 Operating expenses $ (3,757 ) $ (5,170 ) $ (3,374 ) $ (5,016 ) Net loss $ (3,757 ) $ (5,327 ) $ (3,475 ) $ (5,170 ) Net loss per share of common stock — basic and diluted $ (2.07 ) $ (2.36 ) $ (1.31 ) $ (1.95 )

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2016
Subsequent Events [Abstract]
Subsequent Events	19. Subsequent Events On December 30, 2016, the underwriters of the follow-on offering exercised their option to purchase additional shares and on January 6, 2017, the Company issued 600,000 additional shares of its common stock at a public offering price of $9.00 per share for net proceeds of $5.1 million.

Significant Accounting Polici26

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
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”).
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, clinical trial accruals, 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.
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.
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 certain 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 $23.3 million for the period from May 26, 2011 (inception) to December 31, 2016. 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.
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.
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 liabilities 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 based on the estimated fair value of the award at the grant date. 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 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 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 loss until realized. In addition, the Company evaluates the short-investments with unrealized losses to determine whether such losses are other-than-temporary.
Restricted Cash	Restricted Cash The Company is required to maintain a stand-by letter of credit as a security deposit for its new facility lease in Alpharetta, Georgia. The Company’s bank requires the Company to maintain a restricted cash balance to serve as collateral for the letter of credit issued to the landlord by the bank. As of December 31, 2016, the restricted cash balance was invested in a commercial money market account.
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.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Accounting Pronouncements Recently Adopted In August 2014, the Financial Accounting Standards Board ("FASB") Accounting Standards Update (“ Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties About an Entity’s Ability to Continue as a Going Concern In November 2015, the FASB issued ASU 2015-17, Income Taxes (Topic 740) Balance Sheet Classification of Deferred Taxes. The guidance simplifies the presentation of deferred income taxes. The guidance eliminates the current requirement to present deferred tax assets and liabilities as current and noncurrent in a classified balance sheet and now requires entities to classify all deferred tax assets and liabilities as noncurrent. In March 2016, the FASB issued ASU No. 2016-09, Compensation-Stock Compensation (Topic 718). Recent Accounting Pronouncements Not Yet Adopted In May 2014, FASB issued ASU 2014-09, Revenue from Contracts with Customers In February 2016, the FASB issued ASU No. 2016-02, Leases (ASC 842), In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows Classification of Certain Cash Receipts and Cash Payments In November 2016, the FASB issued ASU 2016-18, Restricted Cash,

Property and Equipment, Net (Ta

Property and Equipment, Net (Table)	12 Months Ended
	Dec. 31, 2016
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) December31, 2016 2015 Furniture and fixtures 5 $ 69 $ 66 Machinery and equipment 5 121 121 Computer equipment 3 27 27 Leasehold improvements Lesser of useful life remaining lease term 45 45 262 259 Less: Accumulated depreciation (168 ) (103 ) $ 94 $ 156

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2016
Payables And Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): December 2016 2015 Accrued research and development $ 1,153 $ 569 Accrued bonuses 870 530 Accrued professional fees 410 668 Accrued vacation 72 64 Accrued interest payable 52 15 Accrued expense 234 139 $ 2,791 $ 1,985

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Scheduled Payments for the Loan Agreement	As of December 31, 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 Total 2017 $ — $ 608 $ 608 2018 3,200 476 3,676 2019 3,200 234 3,434 2020 1,600 545 2,145 $ 8,000 $ 1,863 $ 9,863

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2016
Temporary Equity Disclosure [Abstract]
Activity Convertible Preferred Stock	The following table summarizes the activity of convertible preferred stock (in thousands, except per share amounts): Total Series A Series A-1 Series B Series C Convertible Preferred Stock Preferred Stock Preferred Stock Preferred Stock Preferred Shares Amount Shares Amount Shares Amount Shares Amount Stock 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 note and interest payable at $2.69783 per share on August 29, 2014 — — — — 1,197,943 3,232 — — 3,232 Accretion of redeemable convertible preferred stock to redemption value — 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 redeemable convertible preferred stock to redemption value — — — 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 Accretion of redeemable convertible preferred stock to redemption value — — — — — 840 — 44 884 Conversion of preferred stock to common stock at closing of IPO (5,198,826 ) (4,086 ) (4,356,931 ) (7,900 ) (6,009,202 ) (16,212 ) (5,274,674 ) (20,000 ) (48,198 ) Balance at December 31, 2016 — $ — — $ — — $ — — $ — $ —

Share-based compensation (Table

Share-based compensation (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Share-based Compensation Expense	The total share-based compensation expense recognized is reflected in the statements of operations as follows (in thousands): Year Ended December 31, 2016 2015 2014 Research and development $ 539 $ 327 $ 218 General and administrative 775 378 209 Total $ 1,314 $ 705 $ 427
Weighted Average Assumptions Used in Fair Value Calculation for Underlying Common Stock	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, 2016, 2015 and 2014. Year Ended December 31, 2016 2015 2014 Expected term (years) 7.00 7.00 7.00 Expected stock price volatility 97.45 % 86.63 % 85.64 % Risk-free interest rate 2.20 % 2.09 % 1.99 % Expected dividend yield 0.00 % 0.00 % 0.00 %
Summary of Activity Related to Stock Options	The following table summarizes the activity related to stock options during the year ended December 31, 2016: Weighted Number of Average Shares Exercise Price Options outstanding at January 1, 2016 1,261,638 $ 2.41 Granted 1,052,436 9.70 Exercised (10,724 ) 2.84 Cancelled/Forfeited (59,775 ) 4.02 Options outstanding at December 31, 2016 2,243,575 5.78 Options exercisable at December 31, 2015 500,797 0.92 Options exercisable at December 31, 2016 789,120 1.55
Additional Information about the Stock Option Outstanding and Exercisable	The following table provides additional information about the Company’s stock options that were outstanding and exercisable at December 31, 2016 (aggregate intrinsic values in thousands): Weighted Weighted Average Weighted Average Aggregate Remaining Average Aggregate Exercise Options Exercise Intrinsic Contractual Options Exercise Intrinsic Price Outstanding Price Value Life (Years) Exercisable Price Value $0.02 - $0.40 604,897 6.4 538,368 $3.08 - $6.49 706,242 8.5 245,486 $7.14 - $8.90 829,936 9.9 5,266 $20.16 - $20.84 102,500 10.0 — 2,243,575 $ 5.78 $ 7,086 789,120 $ 1.55 $ 5,830

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
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, 2016 2015 2014 Current Deferred tax asset (liability) Non-deductible accrued expenses $ 358 $ 230 $ 20 Deferred rent 1 3 4 Deferred revenue 8 — — Valuation allowance (367 ) (233 ) (24 ) Net current deferred tax asset $ — $ — $ — Non-current Deferred tax asset (liability) Net operating loss carryforwards $ 23,391 $ 14,119 $ 7,891 Stock compensation expense 101 88 70 Depreciation differences (13 ) (28 ) (31 ) Federal tax credits 1,232 850 447 State tax credits 301 262 196 Deferred revenue 61 77 0 Deferred rent — 1 4 Charitable contributions 6 3 3 Valuation allowance (25,079 ) (15,372 ) (8,580 ) 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, 2016 2015 2014 U.S. federal tax rate 34.00 % 34.00 % 34.00 % State tax rate 3.79 4.54 4.41 Permanent difference and other (1.98 ) (1.26 ) (1.15 ) Tax credit 1.62 2.66 4.54 Valuation allowance (37.43 ) (39.94 ) (41.80 ) 0.00 % 0.00 % 0.00 %

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Future Minimum Commitments Due Under Non-Cancelable Operating Leases	Minimum lease payments were as follows at December 31, 2016 (in thousands): 2017 $ 128 2018 431 2019 444 2020 458 2021 472 Thereafter 860 Total minimum lease payments $ 2,793

Available-for Sale Investments

Available-for Sale Investments (Tables)	12 Months Ended
	Dec. 31, 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 December 31, 2016 (in thousands): December 31, 2016 Amortized Unrealized Fair Cost Loss Value Government bonds and agency obligations $ 23,213 $ (8 ) $ 23,205 Commercial paper 12,461 — 12,461 Certificates of deposit 6,579 — 6,579 Corporate bonds 6,567 (5 ) 6,562 Total available-for-sale investments $ 48,820 $ (13 ) $ 48,807

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
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): December 31, 2016 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Cash and money markets $ 29,928 $ — $ — $ 29,928 Restricted cash money market 360 — — 360 Government bonds 19,027 — — 19,027 Certificates of deposit — 6,579 — 6,579 Agency obligations — 4,179 — 4,179 Corporate bonds — 7,262 — 7,262 Commercial paper — 16,656 — 16,656 Total financial assets $ 49,315 $ 34,676 $ — $ 83,991 December 31, 2015 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Cash and money markets $ 20,283 $ — $ — $ 20,283 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 Year Ended December 2016 2015 Stock purchase warrants Balance at beginning of period $ 258 $ 42 Issuance of stock purchase warrants — 164 Exercise of stock purchase warrants (414 ) — Net increase in fair value remeasurement 156 52 Balance at end of period $ — $ 258

Net Loss per Share (Tables)

Net Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Potential Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share	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, 2016 2015 2014 Convertible preferred stock — 9,472,530 7,074,961 Outstanding stock options 2,243,575 1,261,637 1,098,486 Unvested restricted stock — 6,485 20,688 Stock purchase warrants 29,796 146,298 900,724 2,273,371 10,886,950 9,094,859

Quarterly Financial Informati37

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Data [Abstract]
Summary of Quarterly Financial Information	Summarized quarterly financial information for each of the years ended December 31, 2016 and 2015 are as follows (in thousands except per share data): Quarter Ended March 31, 2016 June 30, 2016 September 30, 2016 December 31, 2016 Operating expenses $ (5,862 ) $ (5,183 ) $ (5,311 ) $ (9,362 ) Net loss $ (5,449 ) $ (5,102 ) $ (5,645 ) $ (9,686 ) Net loss per share of common stock — basic and diluted $ (2.05 ) $ (0.62 ) $ (0.28 ) $ (0.45 ) Quarter Ended March 31, 2015 June 30, 2015 September 30, 2015 December 31, 2015 Operating expenses $ (3,757 ) $ (5,170 ) $ (3,374 ) $ (5,016 ) Net loss $ (3,757 ) $ (5,327 ) $ (3,475 ) $ (5,170 ) Net loss per share of common stock — basic and diluted $ (2.07 ) $ (2.36 ) $ (1.31 ) $ (1.95 )

The Company - Additional Inform

The Company - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Dec. 14, 2016	Jun. 07, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016	Jan. 06, 2017	Jul. 06, 2016
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Entity incorporation date			May 26, 2011
Common stock, Sale of shares			24,573,033	2,659,262		24,573,033
Common stock, Share offering price	$ 9
Underwriting discounts and commissions			$ 2,500
Offering expense			$ 400
Public offering closing date			Dec. 14, 2016
Issuance of common stock for follow-on public offering, shares	4,000,000
Issuance of common stock for follow-on public offering, value	$ 33,400		$ 33,459
Proceeds from Issuance of convertible preferred stock and long-term debt			53,900
Cash, cash equivalents and short-term investments			83,600			$ 83,600
Cumulative net cash flows in operating activities			(22,709)	$ (13,902)	$ (9,124)	55,800
Accumulated deficit			$ (65,245)	$ (39,363)		$ (65,245)
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, Sale of shares								948,843
Common stock, Share offering price								$ 7
Net proceeds from issuance of stock								$ 6,100
Over-allotment option by underwriters | Subsequent Event
Organization Consolidation and Presentation of Financial Statements Disclosure [Line Items]
Common stock, Sale of shares							600,000
Common stock, Share offering price							$ 9
Net proceeds from issuance of stock							$ 5,100

Significant Accounting Polici39

Significant Accounting Policies - Additional Information (Detail) $ in Thousands	May 11, 2016	Dec. 31, 2016USD ($)Segment	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2016USD ($)
Accounting Policies [Abstract]
Number of operating segments | Segment		1
Loss from operations | $		$ (25,198)	$ (17,317)	$ (9,823)	$ 23,300
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

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 262	$ 259
Less: Accumulated depreciation	(168)	(103)
Property and equipment, net	94	156
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 69	66
Estimated Useful Lives (Years)	5 years
Machinery and Equipment
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 121	121
Estimated Useful Lives (Years)	5 years
Computer Equipment
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 27	27
Estimated Useful Lives (Years)	3 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 45	$ 45
Estimated Useful Lives (Years)	Lesser of useful life or remaining lease term

Accrued Liabilities - Schedule

Accrued Liabilities - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Accrued research and development	$ 1,153	$ 569
Accrued bonuses	870	530
Accrued professional fees	410	668
Accrued vacation	72	64
Accrued interest payable	52	15
Accrued expense	234	139
Accrued liabilities, current	$ 2,791	$ 1,985

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) - USD ($)	Sep. 28, 2016	Dec. 31, 2016	Dec. 31, 2015	Sep. 30, 2017	May 15, 2015	Apr. 15, 2015	Apr. 01, 2015
Debt Instrument [Line Items]
Long term debt		$ 8,000,000
Interest expense on borrowings		287,000	$ 115,000
Accretion of scheduled final payment		283,000	101,000
Accretion of deferred closing costs		$ 17,000	$ 7,400
Silicon Valley Bank
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity							$ 6,000,000
Long term debt					$ 2,000,000	$ 4,000,000
Long term debt, maturity year		2,018
Debt Instrument, Payment Terms		The Company was 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		$ 300,000
Final payment during maturity, percentage		5.50%
Closing costs recorded in the long-term debt		$ 24,000
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 15,000,000
Long term debt	$ 8,000,000
Interest rate		0.50%
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.
Final payment during maturity		$ 500,000
Final payment during maturity, percentage		6.50%
Debt instrument, description of variable rate basis		30-day U.S. LIBOR
Debt instrument, maturity date		Jun. 1, 2020
Repay all the amount outstanding under the original loan agreement	$ 5,300,000
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust | Scenario Forecast
Debt Instrument [Line Items]
Line of credit facility, remaining borrowing capacity				$ 7,000,000
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust | 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%
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust | 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%
Prime Rate | Silicon Valley Bank
Debt Instrument [Line Items]
Interest rate		0.50%
Floating Interest Rate | Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust
Debt Instrument [Line Items]
Interest rate		7.00%

Long-Term Debt - Scheduled Paym

Long-Term Debt - Scheduled Payments for Loan Agreement (Details) $ in Thousands	Dec. 31, 2016USD ($)
Debt Disclosure [Abstract]
Principal, 2018	$ 3,200
Principal, 2019	3,200
Principal, 2020	1,600
Principal	8,000
Interest and Final Payment, 2017	608
Interest and Final Payment, 2018	476
Interest and Final Payment, 2019	234
Interest and Final Payment, 2020	545
Interest and Final Payment	1,863
Total, 2017	608
Total, 2018	3,676
Total, 2019	3,434
Total, 2020	2,145
Total	$ 9,863

Convertible Shareholder Notes44

Convertible Shareholder Notes Payable (Detail)	1 Months Ended		12 Months Ended
	Aug. 31, 2014$ / sharesshares	Apr. 30, 2014USD ($)Stockholder	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Class Of Stock [Line Items]
Interest expense on borrowings			$ 287,000	$ 115,000
The Bridge Notes
Class Of Stock [Line Items]
Convertible notes principal amount authorized		$ 6,000,000
Issuance of promissory notes		$ 3,000,000
Debt instrument annual interest rate		7.00%
Debt instrument, maturity date		Apr. 30, 2015
Warrants issued to purchase common stock shares | shares	112,802
Class of warrant Exercise | $ / shares	$ 0.02
Interest expense on borrowings					$ 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
The Bridge Notes | Convertible Stock Warrant
Class Of Stock [Line Items]
Number of shares, exercised | shares	112,441
Executive Officer | The Bridge Notes
Class Of Stock [Line Items]
Number of stockholders | Stockholder		2
Director | The Bridge Notes
Class Of Stock [Line Items]
Number of stockholders | Stockholder		1

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Detail) - $ / shares	Dec. 31, 2016	Jun. 07, 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

Convertible Preferred Stock (De

Convertible Preferred Stock (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Class Of Stock [Line Items]
Beginning balance	$ 47,314	$ 26,835	$ 11,871
Issuance of shares, net of issuance cost		19,954	11,501
Conversion of promissory note and interest payable at $2.69783 per share on August 29, 2014			3,232
Accretion of redeemable convertible preferred stock to redemption value	884	525	231
Conversion of preferred stock to common stock at closing of IPO	(48,198)
Ending balance		47,314	26,835
Series A
Class Of Stock [Line Items]
Beginning balance	$ 4,086	$ 4,086	$ 4,040
Beginning balance, shares	5,198,826	5,198,826	5,198,826
Issuance of preferred stock		0	0
Accretion of redeemable convertible preferred stock to redemption value			$ 46
Conversion of preferred stock to common stock at closing of IPO	$ (4,086)
Conversion of preferred stock to common stock at closing of IPO, shares	(5,198,826)
Ending balance		$ 4,086	$ 4,086
Ending balance, shares		5,198,826	5,198,826
Series A-1 Preferred Stock
Class Of Stock [Line Items]
Beginning balance	$ 7,900	$ 7,858	$ 7,831
Beginning balance, shares	4,356,931	4,356,931	4,356,931
Issuance of preferred stock		0	0
Accretion of redeemable convertible preferred stock to redemption value		$ 42	$ 27
Conversion of preferred stock to common stock at closing of IPO	$ (7,900)
Conversion of preferred stock to common stock at closing of IPO, shares	(4,356,931)
Ending balance		$ 7,900	$ 7,858
Ending balance, shares	0	4,356,931	4,356,931
Series B
Class Of Stock [Line Items]
Beginning balance	$ 15,372	$ 14,891
Beginning balance, shares	6,009,202	6,009,202
Issuance of shares, net of issuance cost			$ 11,501
Issuance of preferred stock		0	4,811,259
Conversion of promissory note and interest payable at $2.69783 per share on August 29, 2014			$ 3,232
Conversion of promissory notes, shares			1,197,943
Accretion of redeemable convertible preferred stock to redemption value	$ 840	$ 481	$ 158
Conversion of preferred stock to common stock at closing of IPO	$ (16,212)
Conversion of preferred stock to common stock at closing of IPO, shares	(6,009,202)
Ending balance		$ 15,372	$ 14,891
Ending balance, shares		6,009,202	6,009,202
Series C
Class Of Stock [Line Items]
Beginning balance	$ 19,956
Beginning balance, shares	5,274,674
Issuance of shares, net of issuance cost		$ 19,954
Issuance of preferred stock		5,274,674	0
Accretion of redeemable convertible preferred stock to redemption value	$ 44	$ 2
Conversion of preferred stock to common stock at closing of IPO	$ (20,000)
Conversion of preferred stock to common stock at closing of IPO, shares	(5,274,674)
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) - $ / shares	Dec. 31, 2016	Dec. 31, 2015
Class Of Stock [Line Items]
Common stock, shares authorized	100,000,000	40,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares outstanding	24,573,033	2,659,262
Unvested Restricted Stock
Class Of Stock [Line Items]
Unvested restricted stock, shares	0	6,478

Stock Purchase Warrants - Addit

Stock Purchase Warrants - Additional Information (Details) - USD ($)	Oct. 12, 2016	Jun. 06, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Sep. 30, 2016	Apr. 30, 2015	Dec. 31, 2013
Preferred Stock Warrants | Series A-1 Preferred Stock
Class Of Warrant Or Right [Line Items]
Class of warrant Exercise								$ 1.8132
Warrant exercisable term			10 years
Weighted average remaining life of warrants				6 years 9 months 18 days
Fair value of warrant				$ 58,000
Number of shares, exercised		3,236
Preferred Stock Warrants | Series B Preferred Stock
Class Of Warrant Or Right [Line Items]
Class of warrant Exercise							$ 3.50
Warrant exercisable term			10 years
Weighted average remaining life of warrants				9 years 3 months
Fair value of warrant				$ 200,000
Number of shares, exercised	17,883
Preferred Stock Warrants | Series B Preferred Stock | Convertible Warrant
Class Of Warrant Or Right [Line Items]
Number of stock that can be purchased by each warrant							25,974
Class of warrant Exercise							$ 7.70
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]
Class of warrant Exercise					$ 0.02
Weighted average remaining life of warrants					8 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]
Class of warrant Exercise						$ 10.74
Weighted average remaining life of warrants			9 years 9 months
Warrants expiration term			2026-09
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

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Jan. 01, 2017	Jan. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
2016 Stock Incentive Plan | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares common stock reserved for issuance	1,765,903
Annual increase of common stock reserved for issuance	4.00%
Increase in common stock for future issuance, shares	982,921
2016 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares common stock reserved for issuance		181,818
Share based compensation arrangement description			The number of shares reserved for issuance under the 2016 ESPP will automatically increase for a period of ten years, from January 1, 2017 through January 1, 2026, by the lesser of (i) 1% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, (ii) 454,545 shares of common stock or (iii) a lesser number of shares as may be determined by the Company’s board of directors.
Annual increase of common stock reserved for issuance		1.00%
Employee payroll deductions, percent		15.00%
Number of shares reserved for issuance increase in years		10 years
Addition of common stock shares reserved for future issuance		454,545
2016 Employee Stock Purchase Plan | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares common stock reserved for issuance	427,548
Annual increase of common stock reserved for issuance	1.00%
Addition of common stock shares reserved for future issuance	245,730
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares grants			1,052,436
Option to purchase common stock shares outstanding			2,243,575	1,261,638
Weighted average exercise price			$ 5.78	$ 2.41
Unrecognized compensation expense related to unvested stock options			$ 9.9
Expected to be recognized over a weighted average period			1 year 10 months 24 days
Estimated fair market value per share of common stock			$ 8.94
Stock Options | 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			1,035,200
Weighted average exercise price			$ 9.72
Shares available for future grant			782,982
Stock Options | 2011 Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares grants			0
Option to purchase common stock shares outstanding			1,191,139
Weighted average exercise price			$ 2.32

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Share-based Compensation Expense (Details) - Stock Options - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 1,314	$ 705	$ 427
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	539	327	218
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 775	$ 378	$ 209

Share-Based Compensation - Weig

Share-Based Compensation - Weighted Average Assumptions Used in Fair Value Calculation for Underlying Common Stock (Details) - Stock Options	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Expected term (years)	7 years	7 years	7 years
Expected stock price volatility	97.45%	86.63%	85.64%
Risk-free interest rate	2.20%	2.09%	1.99%
Expected dividend yield	0.00%	0.00%	0.00%

Share-Based Compensation - Su53

Share-Based Compensation - Summary of Activity Related to Stock Options (Details) - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Options outstanding, Beginning balance	1,261,638
Number of Shares, Granted	1,052,436
Number of Shares, Exercised	(10,724)
Number of Shares, Cancelled/Forfeited	(59,775)
Number of Shares, Options outstanding, Ending balance	2,243,575	1,261,638
Number of Shares, Options exercisable	789,120	500,797
Weighted Average Exercise Price, Options outstanding, Beginning balance	$ 2.41
Weighted Average Exercise Price, Granted	9.70
Weighted Average Exercise Price, Exercised	2.84
Weighted Average Exercise Price, Cancelled/Forfeited	4.02
Weighted Average Exercise Price, Options outstanding, Ending balance	5.78	$ 2.41
Weighted Average Exercise Price, Options exercisable	$ 1.55	$ 0.92

Share-Based Compensation - Ad54

Share-Based Compensation - Additional Information about the Stock Option Outstanding and Exercisable (Details) - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options Outstanding	2,243,575	1,261,638
Weighted Average Exercise Price	$ 5.78	$ 2.41
Aggregate Intrinsic Value	$ 7,086
Options Exercisable	789,120	500,797
Weighted Average Exercise Price	$ 1.55	$ 0.92
Aggregate Intrinsic Value	$ 5,830
$0.02 - $0.40
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 0.02
Exercise Price Upper Range Limit	$ 0.40
Options Outstanding	604,897
Weighted Average Remaining Contractual Life (Years)	6 years 4 months 24 days
Options Exercisable	538,368
$3.08 - $6.49
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 3.08
Exercise Price Upper Range Limit	$ 6.49
Options Outstanding	706,242
Weighted Average Remaining Contractual Life (Years)	8 years 6 months
Options Exercisable	245,486
$7.14 - $8.90
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 7.14
Exercise Price Upper Range Limit	$ 8.90
Options Outstanding	829,936
Weighted Average Remaining Contractual Life (Years)	9 years 10 months 24 days
Options Exercisable	5,266
$20.16 - $20.84
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Lower Range Limit	$ 20.16
Exercise Price Upper Range Limit	$ 20.84
Options Outstanding	102,500
Weighted Average Remaining Contractual Life (Years)	10 years

Income Tax - Additional Informa

Income Tax - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Line Items]
Deferred income tax valuation allowance	$ 9,700,000	$ 7,000,000	$ 4,200,000
Net deferred tax assets related to net operating loss carryforwards	$ 23,391,000	$ 14,119,000	$ 7,891,000
Net deferred tax assets related to net operating loss carryforwards expiration year	2,035
U.S. Federal or State Income Taxes [Member]
Income Tax Disclosure [Line Items]
Provision for income taxes	$ 0

Schedule of Net Deferred Tax As

Schedule of Net Deferred Tax Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current
Deferred tax asset (liability) Non-deductible accrued expenses	$ 358	$ 230	$ 20
Deferred rent	1	3	4
Deferred revenue	8
Valuation allowance	(367)	(233)	(24)
Net current deferred tax asset	0	0	0
Non-current
Net operating loss carryforwards	23,391	14,119	7,891
Stock compensation expense	101	88	70
Depreciation differences	(13)	(28)	(31)
Deferred revenue	61	77	0
Deferred rent		1	4
Charitable contributions	6	3	3
Valuation allowance	(25,079)	(15,372)	(8,580)
Net non-current deferred tax asset	0	0	0
Federal
Non-current
Tax credits	1,232	850	447
State
Non-current
Tax credits	$ 301	$ 262	$ 196

Schedule of Statutory and Effec

Schedule of Statutory and Effective Income Tax Rate Reconciliation (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
U.S. federal tax rate	34.00%	34.00%	34.00%
State tax rate	3.79%	4.54%	4.41%
Permanent difference and other	(1.98%)	(1.26%)	(1.15%)
Tax credit	1.62%	2.66%	4.54%
Valuation allowance	(37.43%)	(39.94%)	(41.80%)
Total income tax provision (benefit)	0.00%	0.00%	0.00%

Commitment and Contingencies -

Commitment and Contingencies - Additional Information (Details)	1 Months Ended	12 Months Ended
	Nov. 30, 2016USD ($)ft²	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Commitment And Contingencies [Line Items]
Non-cancelable operating leases, expiration date		2017-03
Rent expense, net of sublease income		$ 81,000	$ 150,000	$ 198,000
GEORGIA
Commitment And Contingencies [Line Items]
Area of office leased | ft²	20,000
Operating lease agreement term	6 years 6 months
Operating lease agreement renewal option term	5 years
Minimum monthly lease payments	$ 35,145
Percentage of increase per year	3.00%

Commitment and Contingencies 59

Commitment and Contingencies - Future Minimum Commitments Due Under Non-Cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2016USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,017	$ 128
2,018	431
2,019	444
2,020	458
2,021	472
Thereafter	860
Total minimum lease payments	$ 2,793

License Agreements - Additional

License Agreements - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2016	Apr. 30, 2015	Aug. 31, 2014
Research And Development Arrangement Contract To Perform For Others [Line Items]
License revenue		$ 520,000
NovaMedica
Research And Development Arrangement Contract To Perform For Others [Line Items]
License revenue		$ 20,000
Patent expirations period		2,027
NovaMedica | Upfront payment
Research And Development Arrangement Contract To Perform For Others [Line Items]
Deferred revenue	$ 200,000			$ 200,000
Spark Therapeutics, Inc. | Upfront payment
Research And Development Arrangement Contract To Perform For Others [Line Items]
License revenue	$ 500,000
Upfront, non-refundable payment			$ 500,000
Rusnano MedInvest LLC
Research And Development Arrangement Contract To Perform For Others [Line Items]
Percentage of voting securities owned subsidiary		6.00%

Collaborative Agreement - Addit

Collaborative Agreement - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development costs	$ 19,455,000	$ 10,762,000	$ 6,692,000
Collaborative Research Agreement
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development costs	$ 83,000	$ 145,000	$ 98,000

Available-for Sale Investments-

Available-for Sale Investments- Summary of Company's Available-For-Sale Investments (Details) $ in Thousands	Dec. 31, 2016USD ($)
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 48,820
Unrealized Loss	(13)
Fair Value	48,807
Government Bonds and Agency Obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	23,213
Unrealized Loss	(8)
Fair Value	23,205
Commercial Paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,461
Fair Value	12,461
Certificates of Deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6,579
Fair Value	6,579
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	6,567
Unrealized Loss	(5)
Fair Value	$ 6,562

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Short-term investments maturity start period	90 days
Short-term investments maturity end period	365 days

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Financial Assets:
Total financial assets	$ 83,991
Stock Purchase Warrants
Financial Liabilities:
Stock purchase warrants		$ 258
Corporate Bonds
Financial Assets:
Total financial assets	7,262
Commercial Paper
Financial Assets:
Total financial assets	16,656
Cash and Money Markets
Financial Assets:
Total financial assets	29,928	20,283
Restricted Cash Money Market
Financial Assets:
Total financial assets	360
Certificates of Deposit
Financial Assets:
Total financial assets	6,579
Government Bonds
Financial Assets:
Total financial assets	19,027
Agency Obligations
Financial Assets:
Total financial assets	4,179
Level 1
Financial Assets:
Total financial assets	49,315
Level 1 | Cash and Money Markets
Financial Assets:
Total financial assets	29,928	20,283
Level 1 | Restricted Cash Money Market
Financial Assets:
Total financial assets	360
Level 1 | Government Bonds
Financial Assets:
Total financial assets	19,027
Level 2
Financial Assets:
Total financial assets	34,676
Level 2 | Corporate Bonds
Financial Assets:
Total financial assets	7,262
Level 2 | Commercial Paper
Financial Assets:
Total financial assets	16,656
Level 2 | Certificates of Deposit
Financial Assets:
Total financial assets	6,579
Level 2 | Agency Obligations
Financial Assets:
Total financial assets	$ 4,179
Level 3 | Stock Purchase Warrants
Financial Liabilities:
Stock purchase warrants		$ 258

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 - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Stock purchase warrants
Balance at beginning of period	$ 258	$ 42
Issuance of stock purchase warrants		164
Exercise of stock purchase warrants	(414)
Net increase in fair value remeasurement	$ 156	52
Balance at end of period		$ 258

Net Loss Per Share - Potential

Net Loss Per Share - Potential Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share (Details) - shares	12 Months Ended
	Dec. 31, 2016	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	2,273,371	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	2,243,575	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 Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	29,796	146,298	900,724
Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		9,472,530	7,074,961

Quarterly Financial Informati67

Quarterly Financial Information (Unaudited) - Summary of Quarterly Financial Information - (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Data [Abstract]
Operating expenses	$ (9,362)	$ (5,311)	$ (5,183)	$ (5,862)	$ (5,016)	$ (3,374)	$ (5,170)	$ (3,757)	$ (25,718)	$ (17,317)	$ (9,823)
Net loss	$ (9,686)	$ (5,645)	$ (5,102)	$ (5,449)	$ (5,170)	$ (3,475)	$ (5,327)	$ (3,757)	$ (25,882)	$ (17,639)	$ (10,189)
Net loss per share of common stock — basic and diluted	$ (0.45)	$ (0.28)	$ (0.62)	$ (2.05)	$ (1.95)	$ (1.31)	$ (2.36)	$ (2.07)	$ (1.97)	$ (7.54)	$ (5.86)

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Jan. 06, 2017	Dec. 31, 2016	Dec. 14, 2016	Jul. 06, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Common stock, Sale of shares		24,573,033			2,659,262
Common stock, Share offering price			$ 9
Over-allotment option by underwriters
Subsequent Event [Line Items]
Common stock, Sale of shares				948,843
Common stock, Share offering price				$ 7
Net proceeds from issuance of stock				$ 6.1
Subsequent Event | Over-allotment option by underwriters
Subsequent Event [Line Items]
Common stock, Sale of shares	600,000
Common stock, Share offering price	$ 9
Net proceeds from issuance of stock	$ 5.1