Clearside Biomedical (CLSD) 10-Q 9 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Nov. 09, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	Clearside Biomedical, Inc.
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Trading Symbol	CLSD
Document Type	10-Q
Entity Central Index Key	1,539,029
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		25,342,445

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 16,289	$ 34,824
Short-term investments	36,338	48,807
Prepaid expenses	712	396
Other current assets	141	290
Total current assets	53,480	84,317
Property and equipment, net	932	94
Restricted cash	360	360
Other assets	103	42
Total assets	54,875	84,813
Current liabilities:
Accounts payable	5,075	2,594
Accrued liabilities	4,004	2,791
Current portion of long-term debt	2,400
Current portion of deferred rent	196	3
Other current liabilities	20	20
Total current liabilities	11,695	5,408
Long-term debt	5,503	7,586
Deferred rent	637
Deferred revenue	145	160
Total liabilities	17,980	13,154
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized and no shares issued at September 30, 2017 and December 31, 2016
Common stock, $0.001 par value; 100,000,000 shares authorized at September 30, 2017 and December 31, 2016; 25,342,445 and 24,573,033 shares issued and outstanding at September 30, 2017 and December 31, 2016, respectively	25	25
Additional paid-in capital	144,605	136,892
Accumulated deficit	(107,727)	(65,245)
Accumulated other comprehensive loss	(8)	(13)
Total stockholders’ equity	36,895	71,659
Total liabilities and stockholders’ equity	$ 54,875	$ 84,813

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares, issued	25,342,445	24,573,033
Common stock, shares outstanding	25,342,445	24,573,033

Statements of Operations and Co

Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
License and collaboration revenue	$ 155	$ 5	$ 290	$ 515
Operating expenses:
Research and development	16,050	3,682	35,118	12,484
General and administrative	2,298	1,629	7,259	3,872
Total operating expenses	18,348	5,311	42,377	16,356
Loss from operations	(18,193)	(5,306)	(42,087)	(15,841)
Other expense, net	(143)	(339)	(395)	(355)
Net loss	$ (18,336)	$ (5,645)	$ (42,482)	$ (16,196)
Net loss per share of common stock — basic and diluted	$ (0.72)	$ (0.28)	$ (1.68)	$ (1.54)
Weighted average shares outstanding — basic and diluted	25,338,462	20,493,377	25,299,910	10,502,459
Net loss	$ (18,336)	$ (5,645)	$ (42,482)	$ (16,196)
Unrealized gain (loss) on available-for-sale investments	15	(5)	5	(5)
Comprehensive loss	$ (18,321)	$ (5,650)	$ (42,477)	$ (16,201)

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities
Net loss	$ (42,482)	$ (16,196)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	135	49
Share-based compensation expense	2,420	776
Non-cash interest expense	159	224
Accretion of debt discount	158	60
Change in fair value of warrant liability		16
Amortization and accretion on available-for-sale investments, net	6	17
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(125)	(536)
Other assets	(61)	426
Accounts payable and accrued liabilities	3,694	(567)
Deferred revenue	(15)	(515)
Deferred rent	121	(7)
Net cash used in operating activities	(35,990)	(16,253)
Investing activities
Purchase of available-for-sale investments	(40,614)	(20,065)
Maturities of available-for-sale investments	53,082
Acquisition of property and equipment	(306)	(3)
Net cash provided by (used in) investing activities	12,162	(20,068)
Financing activities
Proceeds from follow-on public offering, net of issuance costs	5,057
Proceeds from exercise of stock options	196
Proceeds from shares issued under employee stock purchase plan	40
Proceeds from initial public offering, net of issuance costs		51,377
Proceeds from the issuance of long-term debt		7,867
Principal payments made on long-term debt		(6,330)
Net cash provided by financing activities	5,293	52,914
Net (decrease) increase in cash and cash equivalents	(18,535)	16,593
Cash and cash equivalents, beginning of period	34,824	20,283
Cash and cash equivalents, end of period	16,289	36,876
Supplemental schedule of noncash investing and financing activities
Tenant improvements paid by landlord	$ 637
Conversion of convertible preferred stock to common stock		48,198
Reclassification of deferred initial public offering costs		1,597
Unpaid initial public offering costs in accounts payable and accrued expenses		16
Accretion of redeemable convertible preferred stock to redemption value		$ 883

The Company

The Company	9 Months Ended
	Sep. 30, 2017
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 The Company has funded its operations primarily through the proceeds of its public offerings of common stock, sale of convertible preferred stock and the issuance of long-term debt. 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 product 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 $52.6 million as of September 30, 2017. 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. Absent raising additional funds, the Company will delay, reduce or eliminate certain research and development programs or reduce administrative expense while still advancing clinical trials for key product candidates in order that the cash on hand as of the filing date, November 9, 2017, will be sufficient to fund its operations to the end of 2018.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	2. Significant Accounting Policies Basis of Presentation The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“U.S. GAAP”). Unaudited Interim Financial Information The accompanying balance sheet as of September 30, 2017, statements of operations and comprehensive loss for the three and nine months ended September 30, 2017 and 2016 and statements of cash flows for the nine months ended September 30, 2017 and 2016 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2017, its results of operations for the three and nine months ended September 30, 2017 and 2016 and its cash flows for the nine months ended September 30, 2017 and 2016. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2017 and 2016 are unaudited. The results for the three and nine months ended September 30, 2017 are not indicative of results to be expected for the year ending December 31, 2017, any other interim periods or any future year or period. These unaudited financial statements should be read in conjunction with the audited financial statements and related footnotes, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016. 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 estimates and related accrued liabilities, share-based compensation expense and income tax valuation allowance. Actual results could differ from these estimates. 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 trials and nonclinical studies; • costs associated with nonclinical and clinical 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 trials, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the patterns of costs incurred, and are reflected in the financial statements as prepaid or accrued expense. No material adjustments to these estimates have been recorded in these financial statements. Share-Based Compensation The Company recognizes compensation costs related to stock options and restricted stock granted to employees, directors and consultants ratably over the requisite service period, which in most cases is the vesting period of the award for employees, based on the estimated fair value of the awards on the date of grant. 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 the 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 and comprehensive loss 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 certificates of deposit, commercial paper, corporate and government bonds and treasury bills. The Company classifies its short-term investments as available-for-sale securities. Short-term investments are recorded at fair value and unrealized gains and losses are recorded within accumulated other comprehensive income (loss) until realized. In addition, the Company evaluates the short-investments with unrealized losses to determine whether such losses are other-than-temporary. Concentration of Credit Risk Arising From Cash Deposits in Excess of Insured Limits The Company maintains its cash in bank deposits that at times may exceed federally insured limits. The Company has not experienced any loss in such accounts. The Company believes it is not exposed to any significant risks with respect to its cash balances. Recent Accounting Pronouncements Accounting Pronouncements Recently Adopted In March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-09, Compensation-Stock Compensation (Topic 718). 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. Recent Accounting Pronouncements Not Yet Adopted In May 2017, the FASB issued ASU 2017-9 , Compensation-Stock Compensation: Scope of Stock Compensation Modification Accounting financial statements and related disclosures In November 2016, the FASB issued ASU 2016-18, Restricted Cash In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows Classification of Certain Cash Receipts and Cash Payments In February 2016, the FASB issued ASU 2016-02, Leases (ASC 842), In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
	Sep. 30, 2017
Property Plant And Equipment [Abstract]
Property and Equipment, Net	3. Property and Equipment, Net Property and equipment, net consisted of the following (dollar amounts in thousands): Estimated Useful Lives (Years) September 30, 2017 December 2016 Furniture and fixtures 5 $ 303 $ 69 Machinery and equipment 5 121 121 Computer equipment 3 41 27 Leasehold improvements Lesser of useful life remaining lease term 667 45 1,132 262 Less: Accumulated depreciation (200 ) (168 ) $ 932 $ 94 In connection with the Company’s relocation to its new corporate headquarters (see Note 9), the Company wrote off $45,000 of fully amortized leasehold improvements. In addition, the Company wrote off $58,000 of fully depreciated furniture and fixtures that were not re-located to the new corporate headquarters.

Accrued Liabilities

Accrued Liabilities	9 Months Ended
	Sep. 30, 2017
Payables And Accruals [Abstract]
Accrued Liabilities	4. Accrued Liabilities Accrued liabilities consisted of the following (in thousands): September 30, December 2017 2016 Accrued research and development $ 2,766 $ 1,153 Accrued bonuses 695 870 Accrued professional fees 88 410 Accrued vacation 171 72 Accrued interest payable 55 52 Accrued expense 229 234 $ 4,004 $ 2,791

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Long-Term Debt	5. Long-Term Debt Loan and Security Agreements In September 2016, the Company entered into an amended and restated loan and security agreement (the “loan agreement”) with Silicon Valley Bank (“SVB”), MidCap Funding XII Trust and MidCap Financial Trust (together, “MidCap” and collectively with SVB, the “Lenders”), which amended and restated in its entirety the Company’s prior loan and security agreement with SVB dated as of April 14, 2015 (the “original loan agreement”), under which the Company had borrowed $6.0 million in April and May 2015. The loan agreement provides for new term loans of up to $15.0 million, with a floating interest rate equal to 7% plus the greater of (i) the 30-day U.S. LIBOR, reported in the Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue, or (ii) 0.50%. The interest rate on the original loan agreement was equal to the lender’s prime rate less 0.50 percent. Under the terms of the loan agreement, an initial tranche of $8.0 million was advanced on September 28, 2016. The remaining $7.0 million will become available beginning on 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 product candidate CLS-TA for the treatment of macular edema associated with 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 2% of the original principal amount of the aggregate term loans for any prepayments through 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 loan agreement. 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 loan agreements was $168,000 and $43,000 for the three months ended September 30, 2017 and 2016, respectively, and $486,000 and $133,000 for the nine months ended September 30, 2017 and 2016, respectively. Accretion of the scheduled final payment was $53,000 and $156,000 for the three months ended September 30, 2017 and 2016, respectively, and $159,000 and $230,000 for the nine months ended September 30, 2017 and 2016, respectively. Accretion of the deferred debt issuance costs was $53,000 and $190,000 for the three months ended September 30, 2017 and 2016, respectively, and $158,000 and $70,000 for the nine months ended September 30, 2017 and 2016, respectively. As of September 30, 2017, 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 $ — $ 153 $ 153 2018 3,200 476 3,676 2019 3,200 234 3,434 2020 1,600 545 2,145 $ 8,000 $ 1,408 $ 9,408

Common Stock

Common Stock	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Common Stock	6. Common Stock The Company’s amended and restated certificate of incorporation authorizes the Company to issue 100,000,000 shares of $0.001 par value common stock. As of September 30, 2017 and December 31, 2016, there were 25,342,445 and 24,573,033 shares of common stock outstanding, respectively.

Stock Purchase Warrants

Stock Purchase Warrants	9 Months Ended
	Sep. 30, 2017
Stock Purchase Warrants [Abstract]
Stock Purchase Warrants	7. Stock Purchase Warrants In April 2015, in connection with the original loan agreement (see Note 5), the Company issued a warrant to SVB 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 in June 2016 upon the closing of the Company’s initial public offering. This warrant had a fair value of $0.2 million and was net exercised on October 12, 2016, resulting in the issuance of 17,883 shares of common stock. In September 2016, in connection with the loan agreement (see Note 5), 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	9 Months Ended
	Sep. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation	8. Share-Based Compensation Share-based compensation is accounted for in accordance with the provisions of ASC 718, Compensation-Stock Compensation Stock Options The Company has granted stock option awards to employees, directors and consultants from its 2011 Stock Incentive Plan (the “2011 Plan”) and its 2016 Equity Incentive Plan (the “2016 Plan”). The estimated fair value of options granted is determined as of the date of grant using the Black-Scholes option pricing model. The resulting fair value is recognized ratably over the requisite service period, which is generally the vesting period of the awards. Options granted to non-employees are re-measured at each financial reporting period until required services are performed. The following table summarizes the activity related to stock options during the nine months ended September 30, 2017: Weighted Number of Average Shares Exercise Price Options outstanding at January 1, 2017 2,243,575 $ 5.78 Granted 259,250 8.21 Exercised (164,285 ) 1.19 Forfeited (64,250 ) 7.93 Options outstanding at September 30, 2017 2,274,290 6.33 Options exercisable at December 31, 2016 500,797 0.92 Options exercisable at September 30, 2017 846,199 2.26 As of September 30, 2017, the Company had $8.9 million of unrecognized compensation expense related to unvested stock options, which is expected to be recognized over a weighted average period of 2.9 years. Employee Stock Purchase Plan In January 2016, the Company’s board of directors adopted and approved, and in January 2016 the Company’s stockholders approved, the Clearside Biomedical, Inc. 2016 Employee Stock Purchase Plan (the “2016 ESPP”) which became effective on June 1, 2016. The first offering period for the 2016 ESPP commenced January 1, 2017. The 2016 ESPP is considered a compensatory plan and the fair value of the discount and the look-back period are estimated using the Black-Scholes option pricing model and expense is recognized over the six month withholding period prior to the purchase date. During the nine months ended September 30, 2017, the Company issued 5,127 shares of common stock purchased under the 2016 ESPP. Share-based compensation expense for options granted under the 2011 Plan and the 2016 Plan and shares purchased under the 2016 ESPP is reflected in the statements of operations and comprehensive loss as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Research and development $ 349 $ 134 $ 1,006 $ 375 General and administrative 540 148 1,414 401 Total $ 889 $ 282 $ 2,420 $ 776

Commitment and Contingencies

Commitment and Contingencies	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Lease Commitment Summary The Company had previously leased office space under non-cancelable operating leases which expired in March 2017. In November 2016, the Company signed a new office lease agreement to lease approximately 20,000 square feet of office space in Alpharetta, Georgia for its corporate headquarters. The lease agreement is for a 6.5 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. Rent expense under this lease is recognized on a straight-line basis over the term of the lease. In addition, the lease agreement requires payment of the pro-rata share of the annual operating expenses associated with the premises. The Company relocated to this new space in March 2017. Total future minimum lease payments were as follows at September 30, 2017 (in thousands): Year Ending December 31, 2017 $ 105 2018 431 2019 444 2020 458 2021 472 Thereafter 860 Total minimum lease payments $ 2,770 Rent expense was $58,000 and $20,000 for three months ended September 30, 2017 and 2016, respectively, and $156,000 and $61,000 for the nine months ended September 30, 2017 and 2016, 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 and Collaboration Agree

License and Collaboration Agreements	9 Months Ended
	Sep. 30, 2017
License And Collaboration Agreements [Abstract]
License and Collaboration Agreements	10. License and Collaboration 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 of 2016, the Company began recognizing the $200,000 to revenue over the period of time estimated to complete clinical development and commercialization of the Covered Products and the beginning of the first set of patent expirations in 2027. The Company recorded $5,000 and $15,000 of license revenue during each of the three and nine months ended September 30, 2017 and 2016, respectively, for this license agreement. NovaMedica is jointly owned by Rusnano MedInvest LLC and Domain Russia Investments Limited. 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 its terms. During the nine months ended September 30, 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. The Company has periodically entered into other short-term collaboration agreements to evaluate the potential use of its proprietary SCS microinjector with third-party product candidates for the treatment of various diseases. Funds received from these collaboration agreements are recognized as revenue over the term of the agreement. The Company recorded $150,000 and $275,000 of revenue from these collaboration agreements during the three and nine months ended September 30, 2017, respectively.

Available-for-Sale Investments

Available-for-Sale Investments	9 Months Ended
	Sep. 30, 2017
Investments Debt And Equity Securities [Abstract]
Available-for-Sale Investments	11. Available-for-Sale Investments The following table summarizes the Company’s available-for-sale investments (in thousands): September 30, 2017 Amortized Unrealized Fair Cost Losses Value Government bonds and treasury bills $ 13,727 $ (3 ) $ 13,724 Commercial paper 9,512 — 9,512 Certificates of deposit 4,885 — 4,885 Corporate bonds 8,222 (5 ) 8,217 Total available-for-sale investments $ 36,346 $ (8 ) $ 36,338

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	12. Fair Value Measurements The Company records certain financial assets and liabilities at fair value in accordance with the provisions of ASC Topic 820, Fair Value Measurements and Disclosures • Level 1—Unadjusted quoted prices in active, accessible markets for identical assets or liabilities. • Level 2—Other inputs that are directly or indirectly observable in the marketplace. • Level 3—Unobservable inputs that are supported by little or no market activity. The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The Company’s material financial instruments at September 30, 2017 and December 31, 2016 consisted primarily of cash and cash equivalents, short-term investments and long-term debt. The fair value of cash and cash equivalents, government bonds and treasury bills, 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 and commercial paper, 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. There were no significant transfers between Levels 1, 2 and 3 during the nine months ended September 30, 2017 and the year ended December 31, 2016. The following tables summarize the fair value of financial assets that are measured at fair value and the classification by level of input within the fair value hierarchy (in thousands): September 30, 2017 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Cash and money markets $ 13,355 $ — $ — $ 13,355 Restricted cash money market 360 — — 360 Government bonds and treasury bills 13,723 — — 13,723 Certificates of deposit — 5,121 — 5,121 Corporate bonds — 8,217 — 8,217 Commercial paper — 12,211 — 12,211 Total financial assets $ 27,438 $ 25,549 $ — $ 52,987 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

Net Loss per Share

Net Loss per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Net Loss Per Share	13. 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 included stock options 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: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Outstanding stock options 2,274,290 1,414,594 2,274,290 1,414,594 Stock purchase warrants 29,796 55,770 29,796 55,770 2,304,086 1,470,364 2,304,086 1,470,364

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2017
Subsequent Events [Abstract]
Subsequent Event	14 . Subsequent Event On October 31, 2017, the Company entered into an amendment to its loan agreement (see Note 5) with the Lenders. Pursuant to the amendment to the loan agreement, if the Company becomes eligible to draw the remaining $7.0 million tranche under the loan agreement, the Company will be able to draw such funds at its discretion until the earlier of (i) March 31, 2018 and (ii) the occurrence of an event of default under the loan agreement. The Company paid a fee of $35,000 to the Lenders in connection with entering into the amendment.

Significant Accounting Polici20

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
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”).
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying balance sheet as of September 30, 2017, statements of operations and comprehensive loss for the three and nine months ended September 30, 2017 and 2016 and statements of cash flows for the nine months ended September 30, 2017 and 2016 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include normal recurring adjustments, necessary for the fair presentation of the Company’s financial position as of September 30, 2017, its results of operations for the three and nine months ended September 30, 2017 and 2016 and its cash flows for the nine months ended September 30, 2017 and 2016. The financial data and other information disclosed in these notes related to the three and nine months ended September 30, 2017 and 2016 are unaudited. The results for the three and nine months ended September 30, 2017 are not indicative of results to be expected for the year ending December 31, 2017, any other interim periods or any future year or period. These unaudited financial statements should be read in conjunction with the audited financial statements and related footnotes, which are included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016.
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 estimates and related accrued liabilities, share-based compensation expense and income tax valuation allowance. Actual results could differ from these estimates.
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 trials and nonclinical studies; • costs associated with nonclinical and clinical 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 trials, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, or information provided to the Company by its vendors on their actual costs incurred. Payments for these activities are based on the terms of the individual arrangements, which may differ from the patterns of costs incurred, and are reflected in the financial statements as prepaid or accrued expense. No material adjustments to these estimates have been recorded in these financial statements.
Share-Based Compensation	Share-Based Compensation The Company recognizes compensation costs related to stock options and restricted stock granted to employees, directors and consultants ratably over the requisite service period, which in most cases is the vesting period of the award for employees, based on the estimated fair value of the awards on the date of grant. 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 the 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 and comprehensive loss 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 certificates of deposit, commercial paper, corporate and government bonds and treasury bills. The Company classifies its short-term investments as available-for-sale securities. Short-term investments are recorded at fair value and unrealized gains and losses are recorded within accumulated other comprehensive income (loss) until realized. In addition, the Company evaluates the short-investments with unrealized losses to determine whether such losses are other-than-temporary.
Concentration of Credit Risk Arising From Cash Deposits in Excess of Insured Limits	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 March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2016-09, Compensation-Stock Compensation (Topic 718). 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. Recent Accounting Pronouncements Not Yet Adopted In May 2017, the FASB issued ASU 2017-9 , Compensation-Stock Compensation: Scope of Stock Compensation Modification Accounting financial statements and related disclosures In November 2016, the FASB issued ASU 2016-18, Restricted Cash In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows Classification of Certain Cash Receipts and Cash Payments In February 2016, the FASB issued ASU 2016-02, Leases (ASC 842), In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
	Sep. 30, 2017
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net consisted of the following (dollar amounts in thousands): Estimated Useful Lives (Years) September 30, 2017 December 2016 Furniture and fixtures 5 $ 303 $ 69 Machinery and equipment 5 121 121 Computer equipment 3 41 27 Leasehold improvements Lesser of useful life remaining lease term 667 45 1,132 262 Less: Accumulated depreciation (200 ) (168 ) $ 932 $ 94

Accrued Liabilities (Tables)

Accrued Liabilities (Tables)	9 Months Ended
	Sep. 30, 2017
Payables And Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): September 30, December 2017 2016 Accrued research and development $ 2,766 $ 1,153 Accrued bonuses 695 870 Accrued professional fees 88 410 Accrued vacation 171 72 Accrued interest payable 55 52 Accrued expense 229 234 $ 4,004 $ 2,791

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Scheduled Payments for the Loan Agreement	As of September 30, 2017, 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 $ — $ 153 $ 153 2018 3,200 476 3,676 2019 3,200 234 3,434 2020 1,600 545 2,145 $ 8,000 $ 1,408 $ 9,408

Share-Based Compensation (Table

Share-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Activity Related to Stock Options	The following table summarizes the activity related to stock options during the nine months ended September 30, 2017: Weighted Number of Average Shares Exercise Price Options outstanding at January 1, 2017 2,243,575 $ 5.78 Granted 259,250 8.21 Exercised (164,285 ) 1.19 Forfeited (64,250 ) 7.93 Options outstanding at September 30, 2017 2,274,290 6.33 Options exercisable at December 31, 2016 500,797 0.92 Options exercisable at September 30, 2017 846,199 2.26
Summary of Share-based Compensation Expense	Share-based compensation expense for options granted under the 2011 Plan and the 2016 Plan and shares purchased under the 2016 ESPP is reflected in the statements of operations and comprehensive loss as follows (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Research and development $ 349 $ 134 $ 1,006 $ 375 General and administrative 540 148 1,414 401 Total $ 889 $ 282 $ 2,420 $ 776

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments And Contingencies Disclosure [Abstract]
Total Future Minimum Commitments Due Under Non-Cancelable Operating Leases	Total future minimum lease payments were as follows at September 30, 2017 (in thousands): Year Ending December 31, 2017 $ 105 2018 431 2019 444 2020 458 2021 472 Thereafter 860 Total minimum lease payments $ 2,770

Available-for-Sale Investments

Available-for-Sale Investments (Tables)	9 Months Ended
	Sep. 30, 2017
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 (in thousands): September 30, 2017 Amortized Unrealized Fair Cost Losses Value Government bonds and treasury bills $ 13,727 $ (3 ) $ 13,724 Commercial paper 9,512 — 9,512 Certificates of deposit 4,885 — 4,885 Corporate bonds 8,222 (5 ) 8,217 Total available-for-sale investments $ 36,346 $ (8 ) $ 36,338

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Summary of Assets Measured at Fair Value	The following tables summarize the fair value of financial assets that are measured at fair value and the classification by level of input within the fair value hierarchy (in thousands): September 30, 2017 Level 1 Level 2 Level 3 Recorded Value Financial Assets: Cash and money markets $ 13,355 $ — $ — $ 13,355 Restricted cash money market 360 — — 360 Government bonds and treasury bills 13,723 — — 13,723 Certificates of deposit — 5,121 — 5,121 Corporate bonds — 8,217 — 8,217 Commercial paper — 12,211 — 12,211 Total financial assets $ 27,438 $ 25,549 $ — $ 52,987 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

Net Loss per Share (Tables)

Net Loss per Share (Tables)	9 Months Ended
	Sep. 30, 2017
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: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 Outstanding stock options 2,274,290 1,414,594 2,274,290 1,414,594 Stock purchase warrants 29,796 55,770 29,796 55,770 2,304,086 1,470,364 2,304,086 1,470,364

The Company - Additional Inform

The Company - Additional Information (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Entity incorporation date	May 26, 2011
Cash, cash equivalents and short-term investments	$ 52.6

Significant Accounting Polici30

Significant Accounting Policies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
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	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 1,132	$ 262
Less: Accumulated depreciation	(200)	(168)
Property and equipment, net	932	94
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 303	69
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	$ 41	27
Estimated Useful Lives (Years)	3 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and Equipment, gross	$ 667	$ 45
Estimated Useful Lives (Years)	Lesser of useful life or remaining lease term

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details)	9 Months Ended
	Sep. 30, 2017USD ($)
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Amount of property and equipment written off	$ 58,000
Leasehold Improvements
Property Plant And Equipment [Line Items]
Amount of property and equipment written off	$ 45,000

Accrued Liabilities - Schedule

Accrued Liabilities - Schedule of Accrued Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Accrued research and development	$ 2,766	$ 1,153
Accrued bonuses	695	870
Accrued professional fees	88	410
Accrued vacation	171	72
Accrued interest payable	55	52
Accrued expense	229	234
Accrued liabilities, current	$ 4,004	$ 2,791

Long-Term Debt - Additional Inf

Long-Term Debt - Additional Information (Details) - USD ($)	Sep. 28, 2016	Sep. 30, 2016	Apr. 30, 2015	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	May 31, 2015
Debt Instrument [Line Items]
Long term debt				$ 8,000,000		$ 8,000,000
Interest expense on borrowings				168,000	$ 43,000	486,000	$ 133,000
Accretion of scheduled final payment				53,000	156,000	159,000	230,000
Accretion of deferred debt issuance costs				53,000	$ 190,000	158,000	$ 70,000
Silicon Valley Bank | Original Loan Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 6,000,000					$ 6,000,000
Interest rate			0.50%
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust
Debt Instrument [Line Items]
Long term debt	$ 8,000,000
Line of credit facility, remaining borrowing capacity				7,000,000		$ 7,000,000
Debt Instrument, Payment Terms						The Company is required to pay accrued interest only through December 31, 2017 on the outstanding amount, followed by 30 equal payments of principal and accrued interest.
Final payment during maturity, percentage						6.50%
Final payment during maturity				$ 500,000		$ 500,000
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 | Prepayments Through May 31, 2020
Debt Instrument [Line Items]
Prepayment fee percentage of the original principal amount of the aggregate term loans				2.00%		2.00%
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust | Amended and Restated Loan and Security Agreement
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity				$ 15,000,000		$ 15,000,000
Interest rate		0.50%
Debt instrument, description of variable rate basis						30-day U.S. LIBOR
Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust | Floating Interest Rate | Amended and Restated Loan and Security Agreement
Debt Instrument [Line Items]
Interest rate		7.00%

Long-Term Debt - Scheduled Paym

Long-Term Debt - Scheduled Payments for Loan Agreement (Details) $ in Thousands	Sep. 30, 2017USD ($)
Debt Disclosure [Abstract]
Principal, 2018	$ 3,200
Principal, 2019	3,200
Principal, 2020	1,600
Principal	8,000
Interest and Final Payment, 2017	153
Interest and Final Payment, 2018	476
Interest and Final Payment, 2019	234
Interest and Final Payment, 2020	545
Interest and Final Payment	1,408
Total, 2017	153
Total, 2018	3,676
Total, 2019	3,434
Total, 2020	2,145
Total	$ 9,408

Common Stock - Additional Infor

Common Stock - Additional Information (Detail) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Equity [Abstract]
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares outstanding	25,342,445	24,573,033

Stock Purchase Warrants - Addit

Stock Purchase Warrants - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 12, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2016	Apr. 30, 2015
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
Fair value of warrant					$ 0.2
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 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 | Amended and Restated Loan And Security Agreement
Class Of Warrant Or Right [Line Items]
Class of warrant Exercise			$ 10.74
Warrants expiration term		2026-09
Weighted average remaining life of warrants		9 years
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 - Summ

Share-Based Compensation - Summary of Activity Related to Stock Options (Details) - Stock Options - $ / shares	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of Shares, Options outstanding, Beginning balance	2,243,575
Number of Shares, Granted	259,250
Number of Shares, Exercised	(164,285)
Number of Shares, Forfeited	(64,250)
Number of Shares, Options outstanding, Ending balance	2,274,290
Number of Shares, Options exercisable	846,199	500,797
Weighted Average Exercise Price, Options outstanding, Beginning balance	$ 5.78
Weighted Average Exercise Price, Granted	8.21
Weighted Average Exercise Price, Exercised	1.19
Weighted Average Exercise Price, Forfeited	7.93
Weighted Average Exercise Price, Options outstanding, Ending balance	6.33
Weighted Average Exercise Price, Options exercisable	$ 2.26	$ 0.92

Share-Based Compensation - Addi

Share-Based Compensation - Additional Information (Details) $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)shares
2016 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock purchased | shares	5,127
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized compensation expense related to unvested stock options | $	$ 8.9
Expected to be recognized over a weighted average period	2 years 10 months 25 days

Share-Based Compensation - Su40

Share-Based Compensation - Summary of Share-based Compensation Expense (Details) - Stock Options - 2011 Stock Incentive Plan, 2016 Equity Incentive Plan and 2016 Employee Stock Purchase Plan - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 889	$ 282	$ 2,420	$ 776
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	349	134	1,006	375
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Share-based compensation expense	$ 540	$ 148	$ 1,414	$ 401

Commitment and Contingencies -

Commitment and Contingencies - Additional Information (Details)	1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 30, 2016USD ($)ft²	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)
Commitment And Contingencies [Line Items]
Non-cancelable operating leases, expiration date				2017-03
Rent expense		$ 58,000	$ 20,000	$ 156,000	$ 61,000
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 42

Commitment and Contingencies - Total Future Minimum Commitments Due Under Non-Cancelable Operating Leases (Details) $ in Thousands	Sep. 30, 2017USD ($)
Commitments And Contingencies Disclosure [Abstract]
2,017	$ 105
2,018	431
2,019	444
2,020	458
2,021	472
Thereafter	860
Total minimum lease payments	$ 2,770

License and Collaboration Agr43

License and Collaboration Agreements - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Mar. 31, 2016	Apr. 30, 2015	Aug. 31, 2014
Research And Development Arrangement Contract To Perform For Others [Line Items]
Revenue from collaborative agreements	$ 150,000		$ 275,000
NovaMedica
Research And Development Arrangement Contract To Perform For Others [Line Items]
License revenue	$ 5,000	$ 5,000	$ 15,000	$ 15,000
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

Available-for-Sale Investment44

Available-for-Sale Investments - Summary of Company's Available-For-Sale Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 36,346
Unrealized Losses	(8)
Fair Value	36,338	$ 48,807
Government Bonds and Treasury Bills
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	13,727
Unrealized Losses	(3)
Fair Value	13,724
Commercial Paper
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	9,512
Fair Value	9,512
Certificates of Deposit
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,885
Fair Value	4,885
Corporate Bonds
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	8,222
Unrealized Losses	(5)
Fair Value	$ 8,217

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Short-term investments maturity start period	90 days
Short-term investments maturity end period	365 days
Significant transfers between Levels 1, 2 and 3	$ 0	$ 0

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Assets Measured at Fair Value (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Financial Assets:
Total financial assets	$ 52,987	$ 83,991
Government Bonds and Treasury Bills
Financial Assets:
Total financial assets	13,723
Corporate Bonds
Financial Assets:
Total financial assets	8,217	7,262
Commercial Paper
Financial Assets:
Total financial assets	12,211	16,656
Cash and Money Markets
Financial Assets:
Total financial assets	13,355	29,928
Certificates of Deposit
Financial Assets:
Total financial assets	5,121	6,579
Restricted Cash Money Market
Financial Assets:
Total financial assets	360	360
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	27,438	49,315
Level 1 | Government Bonds and Treasury Bills
Financial Assets:
Total financial assets	13,723
Level 1 | Cash and Money Markets
Financial Assets:
Total financial assets	13,355	29,928
Level 1 | Restricted Cash Money Market
Financial Assets:
Total financial assets	360	360
Level 1 | Government Bonds
Financial Assets:
Total financial assets		19,027
Level 2
Financial Assets:
Total financial assets	25,549	34,676
Level 2 | Corporate Bonds
Financial Assets:
Total financial assets	8,217	7,262
Level 2 | Commercial Paper
Financial Assets:
Total financial assets	12,211	16,656
Level 2 | Certificates of Deposit
Financial Assets:
Total financial assets	$ 5,121	6,579
Level 2 | Agency Obligations
Financial Assets:
Total financial assets		$ 4,179

Net Loss Per Share - Potential

Net Loss Per Share - Potential Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	2,304,086	1,470,364	2,304,086	1,470,364
Outstanding Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	2,274,290	1,414,594	2,274,290	1,414,594
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	55,770	29,796	55,770

Subsequent Event - Additional I

Subsequent Event - Additional Information (Details) - Silicon Valley Bank , MidCap Funding XII Trust and MidCap Financial Trust - USD ($)	Oct. 31, 2017	Sep. 30, 2017
Subsequent Event [Line Items]
Line of credit facility, remaining borrowing capacity		$ 7,000,000
Line of credit facility, amendment description		Pursuant to the amendment to the loan agreement, if the Company becomes eligible to draw the remaining $7.0 million tranche under the loan agreement, the Company will be able to draw such funds at its discretion until the earlier of (i) March 31, 2018 and (ii) the occurrence of an event of default under the loan agreement.
Subsequent Event
Subsequent Event [Line Items]
Line of credit facility, remaining borrowing capacity	$ 7,000,000
Line of credit facility, date to be draw remaining borrowing capacity	Mar. 31, 2018
Fee paid to lenders in connection with entering into amendment	$ 35,000