IVERIC bio (ISEE) 10-Q 1 Aug 19 2019 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2019	Jul. 29, 2019
Document And Entity Information
Entity Registrant Name	IVERIC bio, Inc.
Entity Central Index Key	0001410939
Document Type	10-Q
Document Period End Date	Jun. 30, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Smaller Reporting Company	true
Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		41,562,695
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q2

Unaudited Consolidated Balance

Unaudited Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 106,889	$ 131,201
Prepaid expenses and other current assets	1,937	2,086
Income tax receivable	1,765	0
Total current assets	110,591	133,287
Property and equipment, net	252	335
Right-of-use asset, net	989
Income tax receivable, non-current	1,765	3,529
Other assets	11	14
Total assets	113,608	137,165
Current liabilities
Accrued research and development expenses	7,645	7,337
Accounts payable and accrued expenses	3,241	5,869
Lease liability	989
Total current liabilities	11,875	13,206
Total liabilities	11,875	13,206
Stockholders' equity
Preferred stock—$0.001 par value, 5,000,000 shares authorized, no shares issued or outstanding	0	0
Common stock—$0.001 par value, 200,000,000 shares authorized, 41,477,420 and 41,397,197 shares issued and outstanding at June 30, 2019 and December 31, 2018, respectively	41	41
Additional paid-in capital	550,303	545,585
Accumulated deficit	(448,611)	(421,667)
Total stockholders' equity	101,733	123,959
Total liabilities and stockholders' equity	$ 113,608	$ 137,165

Unaudited Consolidated Balanc_2

Unaudited Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	41,477,420	41,397,197
Common stock, shares outstanding (in shares)	41,477,420	41,397,197

Unaudited Consolidated Statemen

Unaudited Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Operating expenses:
Research and development	$ 10,009	$ 8,516	$ 17,694	$ 16,202
General and administrative	5,198	6,332	10,679	11,977
Total operating expenses	15,207	14,848	28,373	28,179
Loss from operations	(15,207)	(14,848)	(28,373)	(28,179)
Interest income	617	602	1,287	1,075
Other income (expense)	151	0	151	(16)
Loss before income tax provision (benefit)	(14,439)	(14,246)	(26,935)	(27,120)
Income tax provision (benefit)	4	(1,037)	9	(838)
Net loss	(14,443)	(13,209)	(26,944)	(26,282)
Comprehensive loss	$ (14,443)	$ (13,209)	$ (26,944)	$ (26,282)
Net loss per common share:
Net loss per common shares - basic and diluted (in dollars per share)	$ (0.35)	$ (0.37)	$ (0.65)	$ (0.73)
Weighted average common shares outstanding:
Weighted average common shares outstanding - basic and dilutive (in shares)	41,477	36,188	41,452	36,171

Unaudited Consolidated Statem_2

Unaudited Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock	Common Stock	Additional paid-in capital	Accumulated Deficit
Balance at beginning of period (in shares) at Dec. 31, 2017		0	36,110
Balance at beginning of period at Dec. 31, 2017	$ 38,041	$ 0	$ 36	$ 522,759	$ (484,754)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plans and warrants (in shares)			54
Issuance of common stock under employee stock compensation plans	27			27
Share-based compensation	3,082			3,082
Net loss	(13,073)				(13,073)
Balance at end of period (in shares) at Mar. 31, 2018		0	36,164
Balance at end of period at Mar. 31, 2018	28,077	$ 0	$ 36	525,868	(497,827)
Balance at beginning of period (in shares) at Dec. 31, 2017		0	36,110
Balance at beginning of period at Dec. 31, 2017	38,041	$ 0	$ 36	522,759	(484,754)
Increase (Decrease) in Stockholders' Equity
Net loss	(26,282)
Balance at end of period (in shares) at Jun. 30, 2018		0	36,188
Balance at end of period at Jun. 30, 2018	17,530	$ 0	$ 36	528,530	(511,036)
Balance at beginning of period (in shares) at Mar. 31, 2018		0	36,164
Balance at beginning of period at Mar. 31, 2018	28,077	$ 0	$ 36	525,868	(497,827)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plans and warrants (in shares)			24
Issuance of common stock under employee stock compensation plans	0
Share-based compensation	2,662			2,662
Net loss	(13,209)				(13,209)
Balance at end of period (in shares) at Jun. 30, 2018		0	36,188
Balance at end of period at Jun. 30, 2018	17,530	$ 0	$ 36	528,530	(511,036)
Balance at beginning of period (in shares) at Dec. 31, 2018		0	41,397
Balance at beginning of period at Dec. 31, 2018	123,959	$ 0	$ 41	545,585	(421,667)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plans and warrants (in shares)			56
Issuance of common stock under employee stock compensation plans	41			41
Share-based compensation	2,470			2,470
Net loss	(12,501)				(12,501)
Balance at end of period (in shares) at Mar. 31, 2019		0	41,453
Balance at end of period at Mar. 31, 2019	113,969	$ 0	$ 41	548,096	(434,168)
Balance at beginning of period (in shares) at Dec. 31, 2018		0	41,397
Balance at beginning of period at Dec. 31, 2018	123,959	$ 0	$ 41	545,585	(421,667)
Increase (Decrease) in Stockholders' Equity
Net loss	(26,944)
Balance at end of period (in shares) at Jun. 30, 2019		0	41,477
Balance at end of period at Jun. 30, 2019	101,733	$ 0	$ 41	550,303	(448,611)
Balance at beginning of period (in shares) at Mar. 31, 2019		0	41,453
Balance at beginning of period at Mar. 31, 2019	113,969	$ 0	$ 41	548,096	(434,168)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plans and warrants (in shares)			24
Issuance of common stock under employee stock compensation plans	0
Share-based compensation	2,207			2,207
Net loss	(14,443)				(14,443)
Balance at end of period (in shares) at Jun. 30, 2019		0	41,477
Balance at end of period at Jun. 30, 2019	$ 101,733	$ 0	$ 41	$ 550,303	$ (448,611)

Unaudited Consolidated Statem_3

Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Operating Activities
Net loss	$ (26,944)	$ (26,282)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and other expense	83	94
Gain on sale of property and equipment	(150)	0
Deferred income taxes	0	233
Share-based compensation	4,677	5,744
Changes in operating assets and liabilities:
Income tax receivable	(1)	1,387
Prepaid expense and other current assets	299	1,227
Other assets	3	(7)
Accrued research and development expenses	308	153
Accounts payable and accrued expenses	(2,628)	(3,557)
Net cash used in operating activities	(24,353)	(21,008)
Investing Activities
Net cash provided by (used in) investing activities	0	0
Financing Activities
Proceeds from employee stock plan purchases	41	27
Net cash provided by financing activities	41	27
Net change in cash and cash equivalents	(24,312)	(20,981)
Cash and cash equivalents
Beginning of period	131,201	166,972
End of period	106,889	145,991
Supplemental disclosure of cash paid
Income tax refunds received	$ 0	$ 2,467

Business

Business	6 Months Ended
	Jun. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business	Business Description of Business and Organization IVERIC bio, Inc. (the “Company”), formerly Ophthotech Corporation, was incorporated on January 5, 2007, in Delaware. The Company is a science-driven biopharmaceutical company with a focus on discovering and developing novel gene therapy solutions to treat orphan inherited retinal diseases ("IRDs") with unmet medical needs. In April 2019, the Company changed its name from Ophthotech Corporation to IVERIC bio, Inc. to reflect the transition of its business to focus principally on gene therapies. The Company believes that gene therapy as a treatment modality, especially gene therapies using adeno-associated virus ("AAV") for gene delivery, holds tremendous promise for retinal diseases. The Company also continues to develop its therapeutic programs, including its ongoing clinical trials for its C5 complement inhibitor Zimura® (avacincaptad pegol) for an age-related retinal disease and for an orphan IRD. The Company's gene therapy portfolio consists of several ongoing research and preclinical development programs that use AAV for gene delivery. These AAV gene therapy programs are targeting the following orphan IRDs: • rhodopsin-mediated autosomal dominant retinitis pigmentosa ("RHO-adRP"), which is characterized by progressive and severe bilateral loss of vision leading to blindness; • IRDs associated with mutations in the BEST1 gene, including Best vitelliform macular dystrophy ("Best disease"), which is generally characterized by bilateral egg yolk-like lesions in the central portion of the retina (the "macula") that, over time, progress to atrophy and loss of vision; • Leber congenital amaurosis type 10 ("LCA10"), which is characterized by severe bilateral loss of vision at or soon after birth; • autosomal recessive Stargardt disease, which is characterized by progressive damage to the macula and retina, leading to loss of vision in children and young adults; and • IRDs associated with mutations in the USH2A gene, which include Usher syndrome type 2A ("Usher 2A") and USH2A -associated nonsyndromatic autosomal recessive retinitis pigmentosa. The Company's therapeutics portfolio consists of Zimura and its program of High temperature requirement A serine peptidase 1 protein ("HtrA1") inhibitors. The Company has Phase 2b clinical trials ongoing evaluating Zimura for the treatment of: • geographic atrophy ("GA"), which is a late-stage form of dry age-related macular degeneration ("AMD") characterized by retinal cell death and degeneration of tissue in the macula, and which may result in loss of vision; and • autosomal recessive Stargardt disease. The Company previously also evaluated Zimura in combination with Lucentis® (ranibizumab), an anti-vascular endothelial growth factor ("anti-VEGF") agent, for the treatment of wet AMD, for which it completed a Phase 2a clinical trial during the fourth quarter of 2018. The Company does not currently have plans to develop Zimura further in wet AMD. The Company's HtrA1 inhibitor program, which it is developing for GA secondary to dry AMD and potentially other age-related retinal diseases, is in the preclinical stage of development. The Company's business development efforts have resulted in the expansion of its research and development pipeline and the transition of the Company to focus principally on gene therapy. The Company initiated multiple gene therapy sponsored research programs with the University of Massachusetts Medical School ("UMMS") in February 2018 and initiated an additional gene therapy sponsored research program with UMMS for USH2A -related IRDs in July 2019. Additionally, the Company in-licensed its novel AAV gene therapy product candidate for the treatment of RHO-adRP ("IC-100") from the University of Florida Research Foundation ("UFRF") and the University of Pennsylvania ("Penn") in June 2018, in-licensed its novel AAV gene therapy product candidate for the treatment of BEST1- related IRDs, including Best disease ("IC-200") from Penn and UFRF in April 2019 and in-licensed its minigene sponsored research program for LCA10 from the University of Massachusetts in July 2019 (See "Note 10—Subsequent Event" for a description of this in-license transaction). The Company also acquired its HtrA1 inhibitor program through the acquisition of Inception 4, Inc. ("Inception 4") in October 2018.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The Company’s significant accounting policies are described in Note 2, “Summary of Significant Accounting Policies,” in the notes to the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2018 filed with the Securities and Exchange Commission ("SEC") on February 28, 2019. Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States ("GAAP") and include all adjustments necessary for the fair presentation of the Company's financial position for the periods presented. The consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Segment and geographic 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 and reporting segment. Use of Estimates The preparation of financial statements and related disclosures in conformity with GAAP requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. The amounts of assets and liabilities reported in the Company's Consolidated Balance Sheets and the amount of expenses reported for each of the periods presented are affected by estimates and assumptions, which are used for, but not limited to, accounting for research and development costs, revenue recognition, accounting for share-based compensation and accounting for income taxes. Actual results could differ from those estimates. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of 90 days or less when purchased to be cash equivalents. The carrying amounts reported in the Balance Sheets for cash and cash equivalents are valued at cost, which approximates their fair value. As of June 30, 2019 , the Company had cash and cash equivalents of approximately $106.9 million . Concentration of Credit Risk The Company's financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents. The Company maintains its cash in bank accounts, the balances of which generally exceed federally insured limits. The Company maintains its cash equivalents in investments in money market funds and, at times, in U.S. Treasury securities and investment-grade corporate debt securities with original maturities of 90 days or less. Concentration of Suppliers The Company currently relies exclusively upon a single third-party contract manufacturer for IC-100 and IC-200, and expects to rely on sole-source suppliers for certain starting materials to be used in the manufacture of such product candidates. The Company currently relies exclusively upon a single third-party manufacturer to provide supplies of the drug substance for Zimura on a purchase order basis. The Company also engages a single third-party manufacturer to provide fill/finish services for clinical supplies of Zimura. In addition, the Company currently relies upon a single third-party supplier to supply it with the polyethylene glycol reagent used to manufacture Zimura on a purchase order basis. Furthermore, the Company and its contract manufacturers currently rely upon sole-source suppliers of certain raw materials and other specialized components of production used in the manufacture and fill/finish of its product candidates. The Company currently relies upon a single third-party contract manufacturer to produce small quantities of the active pharmaceutical ingredient for its HtrA1 inhibitors for preclinical development purposes. If the Company’s third-party manufacturers or fill/finish service providers should become unavailable to the Company for any reason, including as a result of capacity constraints, financial difficulties or insolvency, the Company believes that there are a limited number of potential replacement manufacturers, and the Company likely would incur added costs and delays in identifying or qualifying such replacements. Foreign Currency Translation The Company considers the U.S. dollar to be its functional currency. Expenses denominated in foreign currencies are translated at the exchange rate on the date the expense is incurred. The effect of exchange rate fluctuations on translating foreign currency assets and liabilities into U.S. dollars is included in the Consolidated Statements of Operations and Comprehensive Loss. Foreign exchange transaction gains and losses are included in the results of operations and are not material in the Company's financial statements. Financial Instruments Cash equivalents and available for sale securities are reflected in the accompanying financial statements at fair value. The carrying amount of accounts payable and accrued expenses, including accrued research and development expenses, approximates fair value due to the short-term nature of those instruments. Leases The Company has leased its office space and has entered into various other agreements in conducting its business. At inception, the Company determines whether an agreement represents a lease and at commencement evaluates each lease agreement to determine whether the lease is an operating or financing lease. Some of the Company's lease agreements have contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses, although its remaining outstanding lease for its principal offices has no further options, allowances, holidays or clauses. As described below under "Recently Adopted Accounting Pronouncements," the Company adopted the Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) as of January 1, 2019. Pursuant to ASU 2016-02, all of the Company's leases outstanding on January 1, 2019 continued to be classified as operating leases. With the adoption of ASU 2016-02, the Company recorded an operating lease right-of-use asset and an operating lease liability on its Consolidated Balance Sheet. Right-of-use lease assets represent the Company's right to use the underlying asset for the lease term and the lease obligation represents the Company's commitment to make the lease payments arising from the lease. Right-of-use lease assets and obligations are recognized at the commencement date based on the present value of remaining lease payments over the lease term. As the Company’s leases do not provide an implicit discount rate, the Company has used an estimated incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The right-of-use lease asset includes any lease payments made prior to commencement and excludes any lease incentives. The lease term may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Operating lease expense is recognized on a straight-line basis over the lease term, subject to any changes in the lease or expectations regarding the terms. Variable lease costs such as common area costs and property taxes are expensed as incurred. For all office lease agreements the Company combines lease and nonlease components. Leases with an initial term of 12 months or less are not recorded on the Company's Consolidated Balance Sheet. Prior to the adoption of ASU 2016-02, when the Company's lease agreements contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses, the Company recorded a deferred rent asset or liability equal to the difference between the rent expense and the future minimum lease payments due. The lease expense related to operating leases was recognized on a straight-line basis in the Company's Consolidated Statements of Operations over the term of each lease. In cases where the lessor granted the Company leasehold improvement allowances that reduced the Company's lease expense, the Company capitalized the improvements as incurred and recognized deferred rent, which was amortized over the shorter of the lease term or the expected useful life of the improvements. Property and Equipment Property and equipment, which consists mainly of clinical equipment, computers, software, other office equipment, and leasehold improvements, are carried at cost less accumulated depreciation. Depreciation is computed over the estimated useful lives of the respective assets, generally three to ten years, using the straight-line method. Amortization of leasehold improvements is recorded over the shorter of the lease term or estimated useful life of the related asset. Research and Development The Company's research and development expenses primarily consist of costs associated with the manufacturing, development and preclinical and clinical testing of its product candidates and costs associated with its collaborative gene therapy sponsored research programs. The Company's research and development expenses consist of: • external research and development expenses incurred under arrangements with third parties, such as academic research collaborators, contract research organizations ("CROs"), and contract development and manufacturing organizations ("CDMOs") and other vendors for the production of drug substance and drug product; and • employee-related expenses for employees dedicated to research and development activities, including salaries, benefits and share-based compensation expense. Research and development expenses also include costs of acquired product licenses, in-process research and development, and related technology rights where there is no alternative future use, costs of prototypes used in research and development, consultant fees and amounts paid to collaborative partners. All research and development expenses are charged to operations as incurred in accordance with ASC 730, Research and Development . Income Taxes The Company utilizes the liability method of accounting for deferred income taxes, as set forth in ASC 740, Income Taxes. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the carrying amounts and the tax basis of assets and liabilities. A valuation allowance is established against deferred tax assets when, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company's policy is to record interest and penalties on uncertain tax positions as income tax expense. Share-Based Compensation The Company follows the provisions of ASC 718, Compensation—Stock Compensation, which requires the measurement and recognition of compensation expense for all share-based payment awards made to employees and non-employee directors, including employee stock options, restricted stock units (“RSUs”) and options granted to employees to purchase shares under the 2016 Employee Stock Purchase Plan (the “ESPP”). Share-based compensation expense is based on the grant date fair value estimated in accordance with the provisions of ASC 718 and is generally recognized as an expense over the requisite service period, net of estimated forfeitures. For grants containing performance-based vesting provisions, expense is recognized over the estimated achievement period only when the performance-based milestone is deemed probable of achievement. If performance-based milestones are later determined not to be probable of achievement, then all previously recorded stock-based compensation expense associated with such options will be reversed during the period in which the Company makes this determination. Prior to January 1, 2019, share-based compensation awarded to non-employees was subject to revaluation over the vesting term of each award. Subsequent to the adoption of ASU 2018-07, Improvements to Non-Employee Share-Based Payment Accounting , the value of non-employee share-based compensation is measured on the date of grant, similar to share-based compensation granted to employees. Stock Options The Company estimates the fair value of stock options granted to employees and non-employee directors on the date of grant using the Black-Scholes option-pricing model. Due to the lack of trading history, the Company's computation of stock-price volatility is based on the volatility rates of comparable publicly held companies over a period equal to the expected term of the options granted by the Company. The Company's computation of expected term is determined using the "simplified" method, which is the midpoint between the vesting date and the end of the contractual term. The Company believes that it does not have sufficient reliable exercise data in order to justify the use of a method other than the "simplified" method of estimating the expected exercise term of employee stock option grants. The Company utilizes a dividend yield of zero based on the fact that the Company has never paid cash dividends to stockholders and has no current intentions to pay cash dividends. The risk-free interest rate is based on the zero-coupon U.S. Treasury yield at the date of grant for a term equivalent to the expected term of the option. The weighted-average assumptions used to estimate grant date fair value of stock options using the Black-Scholes option pricing model were as follows for the three and six months ended June 30, 2019 and 2018 : Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Expected common stock price volatility 88% 85% 87% 83% Risk-free interest rate 2.15%-2.31% 2.83%-2.83% 2.15%-2.54% 2.39%-2.83% Expected term of options (years) 5.3 5.3 5.6 5.6 Expected dividend yield — — — — RSUs The Company estimates the fair value of RSUs granted to employees using the closing market price of the Company's common stock on the date of grant. ESPP In April 2016, the board of directors adopted the ESPP pursuant to which the Company may sell up to an aggregate of 1,000,000 shares of common stock. The ESPP was approved by the Company’s stockholders in June 2016. The ESPP is considered compensatory and the fair value of the discount and look back provision are estimated using the Black-Scholes option-pricing model and recognized over the six month withholding period prior to purchase. Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842) . Under the new guidance, lessees will be required to recognize the following for all leases (with the exception of short-term leases) at the commencement date: (1) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (2) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. Under the new guidance, lessor accounting is largely unchanged. Certain targeted improvements were made to align, where necessary, lessor accounting with the lessee accounting model and Topic 606, Revenue from Contracts with Customers . The new lease guidance simplified the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off-balance sheet financing. Publicly-traded business entities should apply the amendments in ASU 2016-2 for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years (i.e., January 1, 2019, for a calendar year entity). Early application is permitted for all publicly-traded business entities and all nonpublicly-traded business entities upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. On January 1, 2019 the Company adopted this guidance utilizing the simplified transition option that allows companies to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company elected to adopt the package of practical expedients permitted in Accounting Standards Codification Topic 842, or ASC 842. Accordingly, the Company continues to account for its existing operating leases as operating leases under the new guidance, without reassessing whether the contracts contain a lease under ASC 842 or whether classification of the operating leases would be different under ASC Topic 842. As a result of the adoption, the Company recognized, as of the beginning of the period of adoption, right-of-use assets and lease liabilities of approximately $1.5 million , which represents the present value of its remaining lease payments using a weighted average estimated incremental borrowing rate of 6% , on its Consolidated Balance Sheet. The adoption of this standard did not have a material impact on the Company’s results of operations for the period ended June 30, 2019 . In June 2018, the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting, which supersedes ASC 505-50 and expands the scope of ASC 718 to include all share-based payments arrangements related to the acquisition of goods and services from both employees and nonemployees. For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2018, including interim periods within those annual periods. During the three months ended March 31, 2019, the Company adopted this guidance. The adoption did not have a material impact on its financial statements for the period ended and as of June 30, 2019 . Recent Accounting Pronouncements In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) , which modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, including, among other changes, the consideration of costs and benefits when evaluating disclosure requirements. For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted. The Company is currently assessing the impact that adopting this new accounting guidance will have on its financial statements and footnote disclosures. In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This guidance is effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the potential effects of this guidance on its consolidated financial statements. In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808) , which clarifies the interaction between the guidance for collaborative arrangements (Topic 808) and the new revenue recognition standard (Topic 606). For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted. The Company is currently assessing the impact that adopting this new accounting guidance will have on its financial statements and footnote disclosures.

Net Loss Per Common Share

Net Loss Per Common Share	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [Abstract]
Net Loss Per Common Share	Net Loss Per Common Share Basic and diluted net loss per common share is determined by dividing net loss by the weighted average common shares outstanding during the period. For the periods where there is a net loss, shares underlying stock options and RSUs have been excluded from the calculation of diluted net loss per common share because the effect of including such shares would be anti-dilutive. Therefore, the weighted average common shares used to calculate both basic and diluted net loss per common share would be the same. The following table sets forth the computation of basic and diluted net loss per common share for the periods indicated: Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Basic and diluted net loss per common share calculation: Net loss $ (14,443 ) $ (13,209 ) $ (26,944 ) $ (26,282 ) Weighted average common shares outstanding - basic and dilutive 41,477 36,188 41,452 36,171 Net loss per share of common stock - basic and diluted $ (0.35 ) $ (0.37 ) $ (0.65 ) $ (0.73 ) The following potentially dilutive securities have been excluded from the computations of diluted weighted average common shares outstanding for the periods presented, as the effect of including such shares would be anti-dilutive: Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Stock options outstanding 5,690 4,818 5,690 4,818 Restricted stock units 635 199 635 199 Total 6,325 5,017 6,325 5,017

Cash, Cash Equivalents and Avai

Cash, Cash Equivalents and Available for Sale Securities	6 Months Ended
	Jun. 30, 2019
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Cash, Cash Equivalents and Available for Sale Securities	Cash, Cash Equivalents and Available for Sale Securities The Company considers all highly liquid investments purchased with original maturities of 90 days or less at the date of purchase to be cash equivalents. As of June 30, 2019 and December 31, 2018, the Company had cash and cash equivalents of approximately $ 106.9 million and $ 131.2 million , respectively. Cash and cash equivalents included cash of $2.3 million at June 30, 2019 and $4.4 million at December 31, 2018. Cash and cash equivalents at June 30, 2019 and December 31, 2018 included $104.6 million and $126.8 million , respectively, of investments in money market funds and certain investment-grade corporate debt securities with original maturities of 90 days or less. The Company considers securities with original maturities of greater than 90 days at the date of purchase to be available for sale securities. The Company held no available for sale securities at June 30, 2019 or at December 31, 2018, respectively. The Company believes that its existing cash and cash equivalents as of June 30, 2019 will be sufficient to fund its operations and capital expenditure requirements as currently planned for at least the next 12 months.

Share-Based Compensation

Share-Based Compensation	6 Months Ended
	Jun. 30, 2019
Share-based Payment Arrangement [Abstract]
Share-Based Compensation	Share-Based Compensation Pursuant to the evergreen provisions of the Company's 2013 stock incentive plan (the "2013 Plan"), annual increases have resulted in the addition of an aggregate of approximately 8,554,000 additional shares to the 2013 Plan, including for 2019, an increase of approximately 1,656,000 shares, or approximately 4% of the total number of shares of the Company's common stock outstanding as of January 1, 2019. As of June 30, 2019 , the Company had approximately 2,704,000 shares available for grant under the 2013 Plan. Share-based compensation expense, net of estimated forfeitures, includes expenses related to stock options and RSUs granted to employees, non-employee directors and consultants, as well as options granted to employees to purchase shares under the ESPP. Stock-based compensation by award type was as follows: Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Stock options $ 1,488 $ 1,836 $ 3,110 $ 3,968 Restricted stock units 709 819 1,530 1,765 Employee stock purchase plan 10 7 37 11 Total $ 2,207 $ 2,662 $ 4,677 $ 5,744 The Company allocated stock-based compensation expense in the Company’s Consolidated Statements of Operations and Comprehensive Loss as follows: Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Research and development $ 989 $ 1,106 $ 2,159 $ 2,546 General and administrative 1,218 1,556 2,518 3,198 Total $ 2,207 $ 2,662 $ 4,677 $ 5,744 Stock Options A summary of the stock option activity, weighted average exercise prices, options outstanding, exercisable and expected to vest as of June 30, 2019 is as follows (in thousands except weighted average exercise price): Number of Shares Underlying Options Weighted Average Exercise Price Outstanding, December 31, 2018 5,903 $ 13.72 Granted 137 $ 1.35 Forfeited (261 ) $ 26.18 Expired (89 ) $ 12.72 Outstanding, June 30, 2019 5,690 $ 12.89 Vested and exercisable, June 30, 2019 2,850 $ 21.83 Vested and expected to vest, June 30, 2019 5,463 $ 13.26 As of June 30, 2019 , there were approximately $6.4 million of unrecognized compensation costs, net of estimated forfeitures, related to stock option awards grants, which are expected to be recognized over a remaining weighted average period of 1.8 years. RSUs The following table presents a summary of the Company's outstanding RSU awards granted as of June 30, 2019 (in thousands except weighted average grant-date fair value): Restricted Stock Units Weighted Average Grant-Date Fair Value Outstanding, December 31, 2018 679 $ 15.61 Awarded 10 $ 1.38 Vested (49 ) $ 52.83 Forfeited (5 ) $ 38.98 Outstanding, June 30, 2019 635 $ 12.40 Outstanding, Expected to vest 518 $ 6.58 As of June 30, 2019 , there were approximately $2.1 million of unrecognized compensation costs, net of estimated forfeitures, related to RSUs grants, which are expected to be recognized over a remaining weighted average period of 1.5 years. ESPP As of June 30, 2019 , there were 920,707 shares available for future purchases under the ESPP. There were no shares of common stock issued under the ESPP during the three months ended June 30, 2019 and 2018. There were 31,522 shares of common stock issued under the ESPP during the six months ended June 30, 2019 . Cash proceeds from ESPP purchases were $41 thousand during the six months ended June 30, 2019 . There were 12,229 shares of common stock issued under the ESPP during the six months ended June 30, 2018 . Cash proceeds from ESPP purchases were $27 thousand during the six months ended June 30, 2018 .

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the three and six months ended June 30, 2019 , the Company recorded a de minimis provision for income taxes. For the three and six months ended June 30, 2018 , the Company recorded a benefit for income taxes of $ 1.0 million and $0.8 million , respectively. The benefit for income taxes recorded during the three months ended June 30, 2018 was to reflect the settlement of a local tax audit. The income tax benefit for the six months ended June 30, 2018 includes the provision for income taxes recorded by the Company for the three months ended March 31, 2018 to reflect the impact of sequestration on the Company's estimate of refundable AMT credits. The Company will continue to evaluate its ability to realize its deferred tax assets on a quarterly basis and will adjust such amounts in light of changing facts and circumstances including, but not limited to, future projections of taxable income, tax legislation, rulings by relevant tax authorities, the progress of ongoing tax audits and the regulatory approval of products currently under development. Any additional changes to the valuation allowance recorded on deferred tax assets in the future would impact the Company’s income taxes.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements ASC 820, Fair Value Measurements and Disclosures , defines fair value as the price that would be received to sell an asset, or paid to transfer a liability, in the principal or most advantageous market in an orderly transaction between market participants on the measurement date. The fair value standard also establishes a three-level hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The Company reviews investments on a periodic basis for other than temporary impairments. This review is subjective as it requires management to evaluate whether an event or change in circumstances has occurred in the period that may have a significant adverse effect on the fair value of the investment. The Company uses the market approach to measure fair value for its financial assets. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets. The Company classifies its investment-grade corporate debt securities within the fair value hierarchy as Level 2 assets, as it primarily utilizes quoted market prices or rates for similar instruments to value these securities. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability on the measurement date. The three levels are defined as follows: • Level 1—inputs to the valuation methodology are quoted prices (unadjusted) for an identical asset or liability in an active market. The Company's Level 1 assets consist of investments in money market funds and U.S. Treasury securities. • Level 2—inputs to the valuation methodology include quoted prices for a similar asset or liability in an active market or model-derived valuations in which all significant inputs are observable for substantially the full term of the asset or liability. The Company's Level 2 assets may consist of investments in investment-grade corporate debt securities. • Level 3—inputs to the valuation methodology are unobservable and significant to the fair value measurement of the asset or liability. The Company does not hold any assets that are measured using Level 3 inputs. The following table presents, for each of the fair value hierarchy levels required under ASC 820, the Company's assets and liabilities that are measured at fair value on a recurring basis as of June 30, 2019 : Fair Value Measurement Using Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets Investments in money market funds* $ 87,572 $ — $ — Investments in investment-grade corporate debt securities* $ — $ 17,031 $ — The following table presents, for each of the fair value hierarchy levels required under ASC 820, the Company's assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2018: Fair Value Measurement Using Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets Investments in money market funds* $ 97,402 $ — $ — Investments in investment-grade corporate debt securities* $ — $ 29,425 $ — * Investments in money market funds and investment-grade corporate debt securities with maturities less than 90 days are reflected in cash and cash equivalents in the accompanying Consolidated Balance Sheets. No transfer of assets between Level 1 and Level 2 of the fair value measurement hierarchy occurred during the three and six months ended June 30, 2019 . The Company held no available for sale securities at June 30, 2019 or at December 31, 2018.

Operating Leases

Operating Leases	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Operating Leases	Operating Leases The Company leases office space located in New York, New York and Princeton, New Jersey under non-cancelable operating lease arrangements. The lease for the Company's New York office space expires at the end of June 2020, whereas the sublease for the Company's Princeton office space expires in March 2020. As of January 1, 2019, the Company recognized right-of-use assets and lease liabilities of approximately $1.5 million , which represents the present value of its remaining lease payments using a weighted average estimated incremental borrowing rate of 6% . For the three and six months ended June 30, 2019 , lease and rent expense was $0.3 million and $0.6 million . Cash paid from operating cash flows for amounts included in the measurement of lease liabilities was $0.3 million and $0.6 million for the three and six months ended June 30, 2019 . At June 30, 2019 , the Company's operating leases had a weighted average remaining lease term of 1.0 year . The following presents the maturity of the Company's operating lease liabilities as of June 30, 2019 : June 30, 2019 Remainder of 2019 $ 520 2020 504 Total remaining obligation 1,024 Less imputed interest (35 ) Present value of lease liabilities $ 989

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Zimura - Archemix Corp. The Company is party to an agreement with Archemix Corp., or Archemix, under which the Company in-licensed rights in certain patents, patent applications and other intellectual property related to Zimura and pursuant to which the Company may be required to pay sublicense fees and make milestone payments (the "C5 License Agreement"). Under the C5 License Agreement, for each anti-C5 aptamer product that the Company may develop under the agreement, including Zimura, the Company is obligated to make payments to Archemix of up to an aggregate of $57.5 million if the Company achieves specified development, clinical and regulatory milestones, with $30.5 million of such payments relating to a first indication, $24.5 million of such payments relating to second and third indications and $2.5 million of such payments relating to sustained delivery applications. Under the C5 License Agreement, the Company is also obligated to make additional payments to Archemix of up to an aggregate of $22.5 million if the Company achieves specified commercial milestones based on net product sales of all anti-C5 products licensed under the agreement. The Company is also obligated to pay Archemix a double-digit percentage of specified non-royalty payments the Company may receive from any sublicensee of its rights under the C5 License Agreement. The Company is not obligated to pay Archemix a running royalty based on net product sales in connection with the C5 License Agreement. IC-100 - University of Florida and the University of Pennsylvania Under its exclusive license agreement with UFRF and Penn for rights to IC-100, the Company is obligated to make payments to UFRF, for the benefit of Penn and UFRF (together, the "Licensors"), of up to an aggregate of $23.5 million if the Company achieves specified clinical, marketing approval and reimbursement approval milestones with respect to a licensed product and up to an aggregate of an additional $70.0 million if the Company achieves specified commercial sales milestones with respect to a licensed product. The Company is also obligated to pay UFRF, for the benefit of the Licensors, a low single-digit percentage of net sales of licensed products. The Company is also obligated to pay UFRF, for the benefit of the Licensors, a double-digit percentage of specified non-royalty payments the Company may receive from any third-party sublicensee of the licensed patent rights. Further, if the Company receives a rare pediatric disease priority review voucher from the U.S. Food and Drug Administration ("FDA") in connection with obtaining marketing approval for a licensed product and the Company subsequently uses such priority review voucher in connection with a different product candidate, the Company will be obligated to pay UFRF, for the benefit of the Licensors, aggregate payments in the low double-digit millions of dollars based on certain approval and commercial sales milestones with respect to such other product candidate. In addition, if the Company sells such a priority review voucher to a third party, the Company will be obligated to pay UFRF, for the benefit of the Licensors, a low double-digit percentage of any consideration received from such third party in connection with such sale. IC-200 - University of Pennsylvania and the University of Florida Under its exclusive license agreement with Penn and UFRF for rights to IC-200, the Company is obligated to make payments to Penn, for the benefit of the Licensors, of up to an aggregate of $15.7 million if the Company achieves specified clinical, marketing approval and reimbursement approval milestones with respect to one licensed product and up to an aggregate of an additional $3.1 million if the Company achieves these same milestones with respect to a different licensed product. In addition, the Company is obligated to make payments to Penn, for the benefit of the Licensors, of up to an aggregate of $48.0 million if the Company achieves specified commercial sales milestones with respect to one licensed product and up to an aggregate of an additional $9.6 million if the Company achieves these same milestones with respect to a different licensed product. The Company is also obligated to pay Penn, for the benefit of the Licensors, a low single-digit percentage of net sales of licensed products. The Company is also obligated to pay Penn, for the benefit of the Licensors, a high single-digit to a mid-teen percentage of specified non-royalty payments the Company may receive from any third-party sublicensee of the licensed patent rights, with the applicable percentage based upon the stage of development of the sublicensed product at the time the Company enters into the sublicense. Further, if the Company receives a rare pediatric disease priority review voucher from the FDA in connection with obtaining marketing approval for a licensed product and the Company subsequently uses such priority review voucher in connection with a different product candidate outside the scope of the agreement, the Company will be obligated to pay Penn, for the benefit of the Licensors, aggregate payments in the low double-digit millions of dollars based on certain approval and commercial sales milestones with respect to such other product candidate. In addition, if the Company sells such a priority review voucher to a third party, the Company will be obligated to pay Penn, for the benefit of the Licensors, a high single-digit percentage of any consideration received from such third party in connection with such sale. HtrA1 Inhibitors - Former Equityholders of Inception 4 Under the agreement and plan of merger pursuant to which the Company acquired Inception 4 (the "Inception 4 Merger Agreement"), the Company is obligated to make payments to the former equityholders of Inception 4 of up to an aggregate of $105 million , subject to the terms and conditions of the Inception 4 Merger Agreement, if the Company achieves certain specified clinical and regulatory milestones with respect to a product candidate from its HtrA1 inhibitor program, with $45 million of such potential payments relating to GA and $60 million of such potential payments relating to wet AMD. Under the Inception 4 Merger Agreement, the Company does not owe any commercial milestones or royalties based on net sales. The future milestone payments will be payable in the form of shares of the Company's common stock, calculated based on the price of its common stock over a five-trading day period preceding the achievement of the relevant milestone, unless and until the issuance of such shares would, together with all other shares issued in connection with the acquisition, exceed an overall maximum limit of approximately 7.2 million shares, which is equal to 19.9% of the number of issued and outstanding shares of the Company's common stock as of the close of business on the business day prior to the closing date of the Inception 4 acquisition, and will be payable in cash thereafter. The Inception 4 Merger Agreement also includes customary indemnification obligations to the former equityholders of Inception 4, including for breaches of the representations and warranties, covenants and agreements of the Company and its subsidiaries (other than Inception 4) in the Inception 4 Merger Agreement. Employment Contracts The Company also has letter agreements with certain employees that require the funding of a specific level of payments if certain events, such as a termination of employment in connection with a change in control or termination of employment by the employee for good reason or by the Company without cause, occur. Contract Service Providers In addition, in the course of normal business operations, the Company has agreements with contract service providers to assist in the performance of the Company’s research and development and manufacturing activities. Expenditures to CROs and CDMOs represent significant costs in preclinical and clinical development. Subject to required notice periods and the Company’s obligations under binding purchase orders and any cancellation fees that the Company may be obligated to pay, the Company can elect to discontinue the work under these agreements at any time. Legal Proceedings On January 11, 2017, a putative class action lawsuit was filed against the Company and certain of its current and former executive officers in the United States District Court for the Southern District of New York, captioned Frank Micholle v. Ophthotech Corporation, et al., No. 1:17-cv-00210. On March 9, 2017, a related putative class action lawsuit was filed against the Company and the same group of its current and former executive officers in the United States District Court for the Southern District of New York, captioned Wasson v. Ophthotech Corporation, et al., No. 1:17-cv-01758. These cases were consolidated on March 13, 2018. On June 4, 2018, the lead plaintiff filed a consolidated amended complaint (the “CAC”). The CAC purports to be brought on behalf of shareholders who purchased the Company’s common stock between March 2, 2015 and December 12, 2016. The CAC generally alleges that the Company and certain of its officers violated Sections 10(b) and/or 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder by making allegedly false and/or misleading statements concerning the results of the Company’s Phase 2b trial and the prospects of the Company’s Phase 3 trials for Fovista in combination with anti-VEGF agents for the treatment of wet AMD. The CAC seeks unspecified damages, attorneys’ fees, and other costs. The Company and individual defendants filed a motion to dismiss the CAC on July 27, 2018. That motion is fully briefed. On February 7, 2018, a shareholder derivative action was filed against the members of the Company’s Board of Directors in the New York Supreme Court Commercial Division, captioned Cano v. Guyer, et al., No. 650601/2018. The complaint alleges that the defendants breached their fiduciary duties to the Company by adopting a compensation plan that overcompensates the non-employee members of the Company's board relative to boards of companies of comparable market capitalization and size. The complaint also alleges that the defendants were unjustly enriched as a result of the alleged conduct. The complaint purports to seek unspecified damages, on behalf of the Company, attorneys’ fees, and other costs, as well as an order directing the Company to reform and improve its corporate governance and internal procedures to comply with applicable laws. The Company filed a motion to dismiss this case on May 14, 2018. On June 4, 2018, the plaintiff filed an amended complaint. On June 25, 2018, the Company filed a renewed motion to dismiss this case. On December 3, 2018, the parties filed a stipulation of settlement that contemplates that the Company will adopt certain compensation-related governance reforms and does not obligate the defendants or the Company to pay any monetary damages. The court approved the settlement at a hearing on March 12, 2019. As part of the settlement, in April 2019 the Company paid $300,000 in fees and costs to plaintiff's counsel. As contemplated by the settlement, the Company's board of directors adopted certain compensation-related governance reforms, including a non-employee director compensation policy, which the Company's stockholders approved on May 15, 2019 at its 2019 annual meeting. On August 31, 2018, a shareholder derivative action was filed against current and former members of the Company's Board of Directors and certain current and former officers of the Company in the United States District Court for the Southern District of New York, captioned Luis Pacheco v. David R. Guyer, et al., Case No. 1:18-cv-07999. The complaint, which is based substantially on the facts alleged in the CAC, alleges that the defendants breached their fiduciary duties to the Company and wasted the Company's corporate assets by failing to oversee the Company's business, and also alleges that the defendants were unjustly enriched as a result of the alleged conduct, including through receipt of bonuses, stock options and similar compensation from the Company, and through sales of the Company's stock between March 2, 2015 and December 12, 2016. The complaint purports to seek unspecified damages on the Company's behalf, attorneys’ fees, and other costs, as well as an order directing the Company to reform and improve its corporate governance and internal procedures to comply with applicable laws, including submitting certain proposed amendments to the Company's corporate charter, bylaws and corporate governance policies for vote by the Company's stockholders. On December 14, 2018, the Company filed a motion to dismiss the complaint. That motion is fully briefed. On October 16, 2018, the Company’s board of directors received a shareholder demand to investigate and commence legal proceedings against certain members of the Company’s board of directors. The demand alleges facts that are substantially similar to the facts alleged in the CAC and the Pacheco complaint and asserts claims that are substantially similar to the claims asserted in the Pacheco complaint. On January 30, 2019, the Company’s board of directors received a second shareholder demand from a different shareholder to investigate and commence legal proceedings against certain current and former members of the Company’s board of directors based on allegations that are substantially similar to the allegations contained in the first demand letter. The Company denies any and all allegations of wrongdoing and intends to vigorously defend against these lawsuits. The Company is unable, however, to predict the outcome of these matters at this time. Moreover, any conclusion of these matters in a manner adverse to the Company and for which it incurs substantial costs or damages not covered by the Company's directors’ and officers’ liability insurance would have a material adverse effect on its financial condition and business. In addition, the litigation could adversely impact the Company's reputation and divert management’s attention and resources from other priorities, including the execution of its business plan and strategies that are important to the Company's ability to grow its business, any of which could have a material adverse effect on the Company's business.

Subsequent Event

Subsequent Event	6 Months Ended
	Jun. 30, 2019
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event miniCEP290 License Agreement On July 22, 2019, the Company entered into an Exclusive License Agreement (the “miniCEP290 License Agreement”) with the University of Massachusetts (“UMass”). The Company entered into the miniCEP290 License Agreement by exercising its exclusive option rights under an option agreement and a sponsored research agreement that the Company previously entered into with UMass in February 2018. Under the miniCEP290 License Agreement, UMass granted the Company a worldwide, exclusive license under specified patent rights and specified biological materials and a non-exclusive license under specified know-how to make, have made, use, offer to sell, sell, have sold and import products for the treatment of diseases associated with mutations in the CEP290 gene, including LCA10. The Company may grant sublicenses of the licensed patent rights and know-how without the consent of UMass. The Company has agreed to use diligent efforts to develop licensed products and to introduce such licensed products into the commercial market. Subject to obtaining marketing approval, the Company agreed to make any approved licensed product reasonably available to the public. In addition, the Company has agreed to meet specified development and regulatory milestones with respect to a licensed product by specified dates, as the same may be extended under the terms of the miniCEP290 License Agreement. Financial Terms The Company has agreed to pay UMass a $0.4 million upfront license fee upon execution of the miniCEP290 License Agreement. In addition, the Company has agreed to issue to UMass 75,000 shares of common stock of the Company, par value $0.001 per share (“Common Stock”), promptly following execution of the miniCEP290 License Agreement pursuant to an exemption from registration afforded by Section 4(a)(2) of the Securities Act of 1933, as amended. The Company has also agreed to pay UMass an annual license maintenance fee in the low double-digit thousands of dollars, which fee will be payable on an annual basis until the expiration of the royalty term for the licensed products. Furthermore, the Company has agreed to reimburse UMass for the costs and expenses of patent prosecution and maintenance related to the licensed patent rights. The Company has further agreed to pay UMass up to an aggregate of $14.75 million in cash and issue up to 75,000 shares of Common Stock if the Company achieves specified clinical and regulatory milestones with respect to a licensed product. In addition, the Company has agreed to pay UMass up to an aggregate of $48.0 million if the Company achieves specified commercial sales milestones with respect to a licensed product. The Company is also obligated to pay UMass royalties at a low single-digit percentage of net sales of licensed products. The Company's obligation to pay royalties under the miniCEP290 License Agreement will continue on a licensed product-by-licensed product and country-by-country basis until the later of: (a) the expiration of the last-to-expire licensed patent rights covering the sale of the applicable licensed product in the country of sale, or (b) 10 years from the first commercial sale of the applicable licensed product in the country of sale. Beginning with the calendar year following receipt of marketing approval for a licensed product, the Company is also obligated to pay certain minimum royalties, not to exceed an amount in the mid-double-digit thousands of dollars on an annual basis, which minimum royalties are creditable against the Company’s royalty obligation with respect to net sales of licensed products due in the year the minimum royalty is paid. If the Company or any of its affiliates sublicenses any of the licensed patent rights or know-how to a third party, the Company will be obligated to pay UMass a high single-digit to a mid-tens percentage of the consideration received in exchange for such sublicense, with the applicable percentage based upon the stage of development of the licensed products at the time the Company or the applicable affiliate enters into the sublicense. If the Company receives a rare pediatric disease priority review voucher (a “priority review voucher”) from the FDA in connection with obtaining marketing approval for a licensed product, and the Company subsequently uses such priority review voucher in connection with a different product candidate outside the scope of the miniCEP290 License Agreement, the Company will be obligated to pay UMass a low-tens percentage of the fair market value of the priority review voucher at the time of approval of such product candidate and a low-twenties percentage of the fair market value of the priority review voucher at the time of achievement of a specified commercial sales milestone for such other product candidate. In addition, if the Company sells such a priority review voucher to a third party, the Company will be obligated to pay UMass a low-thirties percentage of any consideration received from such third party in connection with such sale. Term and Termination The miniCEP290 License Agreement, unless earlier terminated by the Company or UMass, will expire upon the expiration of the Company's obligation to pay royalties to UMass on net sales of licensed products. The Company may terminate the miniCEP290 License Agreement at any time for any reason upon prior written notice to UMass. The Company may also terminate the miniCEP290 License Agreement if UMass materially breaches the miniCEP290 License Agreement and does not cure such breach within a specified cure period. UMass may terminate the miniCEP290 License Agreement if the Company materially breaches the miniCEP290 License Agreement and does not cure such breach within a specified cure period. Following any termination of the miniCEP290 License Agreement prior to expiration of the term of the miniCEP290 License Agreement, all rights to the licensed patent rights and know-how that UMass granted to the Company will revert to UMass. Other Provisions The miniCEP290 License Agreement contains patent prosecution and maintenance, indemnification and dispute resolution provisions that are customary for agreements of this kind.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies - (Policies)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States ("GAAP") and include all adjustments necessary for the fair presentation of the Company's financial position for the periods presented.
Consolidation	The consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Segment and geographic information	Segment and geographic 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 and reporting segment.
Use of Estimates	Use of Estimates The preparation of financial statements and related disclosures in conformity with GAAP requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. The amounts of assets and liabilities reported in the Company's Consolidated Balance Sheets and the amount of expenses reported for each of the periods presented are affected by estimates and assumptions, which are used for, but not limited to, accounting for research and development costs, revenue recognition, accounting for share-based compensation and accounting for income taxes. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of 90 days or less when purchased to be cash equivalents. The carrying amounts reported in the Balance Sheets for cash and cash equivalents are valued at cost, which approximates their fair value.
Concentration of Credit Risk	Concentration of Credit Risk The Company's financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents. The Company maintains its cash in bank accounts, the balances of which generally exceed federally insured limits. The Company maintains its cash equivalents in investments in money market funds and, at times, in U.S. Treasury securities and investment-grade corporate debt securities with original maturities of 90 days or less.
Concentration of Suppliers	Concentration of Suppliers The Company currently relies exclusively upon a single third-party contract manufacturer for IC-100 and IC-200, and expects to rely on sole-source suppliers for certain starting materials to be used in the manufacture of such product candidates. The Company currently relies exclusively upon a single third-party manufacturer to provide supplies of the drug substance for Zimura on a purchase order basis. The Company also engages a single third-party manufacturer to provide fill/finish services for clinical supplies of Zimura. In addition, the Company currently relies upon a single third-party supplier to supply it with the polyethylene glycol reagent used to manufacture Zimura on a purchase order basis. Furthermore, the Company and its contract manufacturers currently rely upon sole-source suppliers of certain raw materials and other specialized components of production used in the manufacture and fill/finish of its product candidates. The Company currently relies upon a single third-party contract manufacturer to produce small quantities of the active pharmaceutical ingredient for its HtrA1 inhibitors for preclinical development purposes. If the Company’s third-party manufacturers or fill/finish service providers should become unavailable to the Company for any reason, including as a result of capacity constraints, financial difficulties or insolvency, the Company believes that there are a limited number of potential replacement manufacturers, and the Company likely would incur added costs and delays in identifying or qualifying such replacements.
Foreign Currency Translation	Foreign Currency Translation The Company considers the U.S. dollar to be its functional currency. Expenses denominated in foreign currencies are translated at the exchange rate on the date the expense is incurred. The effect of exchange rate fluctuations on translating foreign currency assets and liabilities into U.S. dollars is included in the Consolidated Statements of Operations and Comprehensive Loss. Foreign exchange transaction gains and losses are included in the results of operations and are not material in the Company's financial statements.
Financial Instruments	Financial Instruments Cash equivalents and available for sale securities are reflected in the accompanying financial statements at fair value. The carrying amount of accounts payable and accrued expenses, including accrued research and development expenses, approximates fair value due to the short-term nature of those instruments.
Leases	Leases The Company has leased its office space and has entered into various other agreements in conducting its business. At inception, the Company determines whether an agreement represents a lease and at commencement evaluates each lease agreement to determine whether the lease is an operating or financing lease. Some of the Company's lease agreements have contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses, although its remaining outstanding lease for its principal offices has no further options, allowances, holidays or clauses. As described below under "Recently Adopted Accounting Pronouncements," the Company adopted the Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) as of January 1, 2019. Pursuant to ASU 2016-02, all of the Company's leases outstanding on January 1, 2019 continued to be classified as operating leases. With the adoption of ASU 2016-02, the Company recorded an operating lease right-of-use asset and an operating lease liability on its Consolidated Balance Sheet. Right-of-use lease assets represent the Company's right to use the underlying asset for the lease term and the lease obligation represents the Company's commitment to make the lease payments arising from the lease. Right-of-use lease assets and obligations are recognized at the commencement date based on the present value of remaining lease payments over the lease term. As the Company’s leases do not provide an implicit discount rate, the Company has used an estimated incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The right-of-use lease asset includes any lease payments made prior to commencement and excludes any lease incentives. The lease term may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Operating lease expense is recognized on a straight-line basis over the lease term, subject to any changes in the lease or expectations regarding the terms. Variable lease costs such as common area costs and property taxes are expensed as incurred. For all office lease agreements the Company combines lease and nonlease components. Leases with an initial term of 12 months or less are not recorded on the Company's Consolidated Balance Sheet. Prior to the adoption of ASU 2016-02, when the Company's lease agreements contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses, the Company recorded a deferred rent asset or liability equal to the difference between the rent expense and the future minimum lease payments due. The lease expense related to operating leases was recognized on a straight-line basis in the Company's Consolidated Statements of Operations over the term of each lease. In cases where the lessor granted the Company leasehold improvement allowances that reduced the Company's lease expense, the Company capitalized the improvements as incurred and recognized deferred rent, which was amortized over the shorter of the lease term or the expected useful life of the improvements.
Property and Equipment	Property and Equipment Property and equipment, which consists mainly of clinical equipment, computers, software, other office equipment, and leasehold improvements, are carried at cost less accumulated depreciation. Depreciation is computed over the estimated useful lives of the respective assets, generally three to ten years, using the straight-line method. Amortization of leasehold improvements is recorded over the shorter of the lease term or estimated useful life of the related asset. Research and Developmen
Research and Development	Research and Development The Company's research and development expenses primarily consist of costs associated with the manufacturing, development and preclinical and clinical testing of its product candidates and costs associated with its collaborative gene therapy sponsored research programs. The Company's research and development expenses consist of: • external research and development expenses incurred under arrangements with third parties, such as academic research collaborators, contract research organizations ("CROs"), and contract development and manufacturing organizations ("CDMOs") and other vendors for the production of drug substance and drug product; and • employee-related expenses for employees dedicated to research and development activities, including salaries, benefits and share-based compensation expense. Research and development expenses also include costs of acquired product licenses, in-process research and development, and related technology rights where there is no alternative future use, costs of prototypes used in research and development, consultant fees and amounts paid to collaborative partners. All research and development expenses are charged to operations as incurred in accordance with ASC 730, Research and Development .
Income Taxes	Income Taxes The Company utilizes the liability method of accounting for deferred income taxes, as set forth in ASC 740, Income Taxes. Under this method, deferred tax assets and liabilities are recognized for the expected future tax consequences of temporary differences between the carrying amounts and the tax basis of assets and liabilities. A valuation allowance is established against deferred tax assets when, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company's policy is to record interest and penalties on uncertain tax positions as income tax expense.
Share-Based Compensation	Share-Based Compensation The Company follows the provisions of ASC 718, Compensation—Stock Compensation, which requires the measurement and recognition of compensation expense for all share-based payment awards made to employees and non-employee directors, including employee stock options, restricted stock units (“RSUs”) and options granted to employees to purchase shares under the 2016 Employee Stock Purchase Plan (the “ESPP”). Share-based compensation expense is based on the grant date fair value estimated in accordance with the provisions of ASC 718 and is generally recognized as an expense over the requisite service period, net of estimated forfeitures. For grants containing performance-based vesting provisions, expense is recognized over the estimated achievement period only when the performance-based milestone is deemed probable of achievement. If performance-based milestones are later determined not to be probable of achievement, then all previously recorded stock-based compensation expense associated with such options will be reversed during the period in which the Company makes this determination. Prior to January 1, 2019, share-based compensation awarded to non-employees was subject to revaluation over the vesting term of each award. Subsequent to the adoption of ASU 2018-07, Improvements to Non-Employee Share-Based Payment Accounting , the value of non-employee share-based compensation is measured on the date of grant, similar to share-based compensation granted to employees. Stock Options The Company estimates the fair value of stock options granted to employees and non-employee directors on the date of grant using the Black-Scholes option-pricing model. Due to the lack of trading history, the Company's computation of stock-price volatility is based on the volatility rates of comparable publicly held companies over a period equal to the expected term of the options granted by the Company. The Company's computation of expected term is determined using the "simplified" method, which is the midpoint between the vesting date and the end of the contractual term. The Company believes that it does not have sufficient reliable exercise data in order to justify the use of a method other than the "simplified" method of estimating the expected exercise term of employee stock option grants. The Company utilizes a dividend yield of zero based on the fact that the Company has never paid cash dividends to stockholders and has no current intentions to pay cash dividends. The risk-free interest rate is based on the zero-coupon U.S. Treasury yield at the date of grant for a term equivalent to the expected term of the option. The weighted-average assumptions used to estimate grant date fair value of stock options using the Black-Scholes option pricing model were as follows for the three and six months ended June 30, 2019 and 2018 : Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Expected common stock price volatility 88% 85% 87% 83% Risk-free interest rate 2.15%-2.31% 2.83%-2.83% 2.15%-2.54% 2.39%-2.83% Expected term of options (years) 5.3 5.3 5.6 5.6 Expected dividend yield — — — — RSUs The Company estimates the fair value of RSUs granted to employees using the closing market price of the Company's common stock on the date of grant. ESPP In April 2016, the board of directors adopted the ESPP pursuant to which the Company may sell up to an aggregate of 1,000,000 shares of common stock. The ESPP was approved by the Company’s stockholders in June 2016. The ESPP is considered compensatory and the fair value of the discount and look back provision are estimated using the Black-Scholes option-pricing model and recognized over the six month withholding period prior to purchase.
Recently Adopted and Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842) . Under the new guidance, lessees will be required to recognize the following for all leases (with the exception of short-term leases) at the commencement date: (1) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (2) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. Under the new guidance, lessor accounting is largely unchanged. Certain targeted improvements were made to align, where necessary, lessor accounting with the lessee accounting model and Topic 606, Revenue from Contracts with Customers . The new lease guidance simplified the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off-balance sheet financing. Publicly-traded business entities should apply the amendments in ASU 2016-2 for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years (i.e., January 1, 2019, for a calendar year entity). Early application is permitted for all publicly-traded business entities and all nonpublicly-traded business entities upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. On January 1, 2019 the Company adopted this guidance utilizing the simplified transition option that allows companies to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company elected to adopt the package of practical expedients permitted in Accounting Standards Codification Topic 842, or ASC 842. Accordingly, the Company continues to account for its existing operating leases as operating leases under the new guidance, without reassessing whether the contracts contain a lease under ASC 842 or whether classification of the operating leases would be different under ASC Topic 842. As a result of the adoption, the Company recognized, as of the beginning of the period of adoption, right-of-use assets and lease liabilities of approximately $1.5 million , which represents the present value of its remaining lease payments using a weighted average estimated incremental borrowing rate of 6% , on its Consolidated Balance Sheet. The adoption of this standard did not have a material impact on the Company’s results of operations for the period ended June 30, 2019 . In June 2018, the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting, which supersedes ASC 505-50 and expands the scope of ASC 718 to include all share-based payments arrangements related to the acquisition of goods and services from both employees and nonemployees. For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2018, including interim periods within those annual periods. During the three months ended March 31, 2019, the Company adopted this guidance. The adoption did not have a material impact on its financial statements for the period ended and as of June 30, 2019 . Recent Accounting Pronouncements In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) , which modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, including, among other changes, the consideration of costs and benefits when evaluating disclosure requirements. For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted. The Company is currently assessing the impact that adopting this new accounting guidance will have on its financial statements and footnote disclosures. In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This guidance is effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years, with early adoption permitted. The Company is currently evaluating the potential effects of this guidance on its consolidated financial statements. In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808) , which clarifies the interaction between the guidance for collaborative arrangements (Topic 808) and the new revenue recognition standard (Topic 606). For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted. The Company is currently assessing the impact that adopting this new accounting guidance will have on its financial statements and footnote disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - (Tables)	6 Months Ended
	Jun. 30, 2019
Accounting Policies [Abstract]
Schedule of weighted-average assumptions used to estimate grant date fair value of stock options	The weighted-average assumptions used to estimate grant date fair value of stock options using the Black-Scholes option pricing model were as follows for the three and six months ended June 30, 2019 and 2018 : Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Expected common stock price volatility 88% 85% 87% 83% Risk-free interest rate 2.15%-2.31% 2.83%-2.83% 2.15%-2.54% 2.39%-2.83% Expected term of options (years) 5.3 5.3 5.6 5.6 Expected dividend yield — — — —

Net Loss Per Common Share - (Ta

Net Loss Per Common Share - (Tables)	6 Months Ended
	Jun. 30, 2019
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted net income (loss) per common share	The following table sets forth the computation of basic and diluted net loss per common share for the periods indicated: Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Basic and diluted net loss per common share calculation: Net loss $ (14,443 ) $ (13,209 ) $ (26,944 ) $ (26,282 ) Weighted average common shares outstanding - basic and dilutive 41,477 36,188 41,452 36,171 Net loss per share of common stock - basic and diluted $ (0.35 ) $ (0.37 ) $ (0.65 ) $ (0.73 )
Schedule of potentially dilutive securities that have been excluded from the computations of diluted weighted average common shares outstanding	The following potentially dilutive securities have been excluded from the computations of diluted weighted average common shares outstanding for the periods presented, as the effect of including such shares would be anti-dilutive: Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Stock options outstanding 5,690 4,818 5,690 4,818 Restricted stock units 635 199 635 199 Total 6,325 5,017 6,325 5,017

Share-Based Compensation - (Tab

Share-Based Compensation - (Tables)	6 Months Ended
	Jun. 30, 2019
Share-based Payment Arrangement [Abstract]
Schedule of Allocation of Share-based Compensation Costs by Award Type	Share-based compensation expense, net of estimated forfeitures, includes expenses related to stock options and RSUs granted to employees, non-employee directors and consultants, as well as options granted to employees to purchase shares under the ESPP. Stock-based compensation by award type was as follows: Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Stock options $ 1,488 $ 1,836 $ 3,110 $ 3,968 Restricted stock units 709 819 1,530 1,765 Employee stock purchase plan 10 7 37 11 Total $ 2,207 $ 2,662 $ 4,677 $ 5,744
Schedule of Allocation of Share-based Compensation Costs by Financial Statement Line	The Company allocated stock-based compensation expense in the Company’s Consolidated Statements of Operations and Comprehensive Loss as follows: Three Months Ended June 30, Six Months Ended June 30, 2019 2018 2019 2018 Research and development $ 989 $ 1,106 $ 2,159 $ 2,546 General and administrative 1,218 1,556 2,518 3,198 Total $ 2,207 $ 2,662 $ 4,677 $ 5,744
Summary of the stock option activity including weighted average exercise prices, options outstanding and exercisable	A summary of the stock option activity, weighted average exercise prices, options outstanding, exercisable and expected to vest as of June 30, 2019 is as follows (in thousands except weighted average exercise price): Number of Shares Underlying Options Weighted Average Exercise Price Outstanding, December 31, 2018 5,903 $ 13.72 Granted 137 $ 1.35 Forfeited (261 ) $ 26.18 Expired (89 ) $ 12.72 Outstanding, June 30, 2019 5,690 $ 12.89 Vested and exercisable, June 30, 2019 2,850 $ 21.83 Vested and expected to vest, June 30, 2019 5,463 $ 13.26
Summary of the Company's outstanding shares of RSU awards	The following table presents a summary of the Company's outstanding RSU awards granted as of June 30, 2019 (in thousands except weighted average grant-date fair value): Restricted Stock Units Weighted Average Grant-Date Fair Value Outstanding, December 31, 2018 679 $ 15.61 Awarded 10 $ 1.38 Vested (49 ) $ 52.83 Forfeited (5 ) $ 38.98 Outstanding, June 30, 2019 635 $ 12.40 Outstanding, Expected to vest 518 $ 6.58

Fair Value Measurements - (Tabl

Fair Value Measurements - (Tables)	6 Months Ended
	Jun. 30, 2019
Fair Value Disclosures [Abstract]
Schedule of assets and liabilities that are measured at fair value on a recurring basis	The following table presents, for each of the fair value hierarchy levels required under ASC 820, the Company's assets and liabilities that are measured at fair value on a recurring basis as of June 30, 2019 : Fair Value Measurement Using Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets Investments in money market funds* $ 87,572 $ — $ — Investments in investment-grade corporate debt securities* $ — $ 17,031 $ — The following table presents, for each of the fair value hierarchy levels required under ASC 820, the Company's assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2018: Fair Value Measurement Using Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets Investments in money market funds* $ 97,402 $ — $ — Investments in investment-grade corporate debt securities* $ — $ 29,425 $ — * Investments in money market funds and investment-grade corporate debt securities with maturities less than 90 days are reflected in cash and cash equivalents in the accompanying Consolidated Balance Sheets.

Operating Leases - (Tables)

Operating Leases - (Tables)	6 Months Ended
	Jun. 30, 2019
Leases [Abstract]
Summary of Operating Lease Liability, Maturity	The following presents the maturity of the Company's operating lease liabilities as of June 30, 2019 : June 30, 2019 Remainder of 2019 $ 520 2020 504 Total remaining obligation 1,024 Less imputed interest (35 ) Present value of lease liabilities $ 989

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Segment and Geographic Information (Details)	6 Months Ended
	Jun. 30, 2019segment
Accounting Policies [Abstract]
Number of operating segments	1
Number of reporting segments	1

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Cash and cash equivalents	$ 106,889	$ 131,201

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Property and Equipment (Details)	6 Months Ended
	Jun. 30, 2019
Minimum
Property and equipment
Estimated useful lives	3 years
Maximum
Property and equipment
Estimated useful lives	10 years

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Share-Based Compensation (Details) - shares	6 Months Ended
	Jun. 30, 2019	Apr. 30, 2016
Share-Based Compensation
Expected dividend yield	0.00%
ESPP | Maximum
Share-Based Compensation
Number of shares reserved for issuance under the Plan (in shares)		1,000,000

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Schedule of Weighted-Average Assumptions (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield			0.00%
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected common stock price volatility	88.00%	85.00%	87.00%	83.00%
Risk-free interest rate, minimum	2.15%	2.83%	2.15%	2.39%
Risk-free interest rate, maximum	2.31%	2.83%	2.54%	2.83%
Expected term of options (years)	5 years 3 months 18 days	5 years 3 months 18 days	5 years 7 months 6 days	5 years 7 months 6 days
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Recently Adopted Accounting Pronouncements (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset, net	$ 989
Operating lease liability	$ 989
Estimated incremental borrowing rate		6.00%
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset, net		$ 1,500
Operating lease liability		$ 1,500

Net Loss Per Common Share (Deta

Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Basic and diluted net loss per common share calculation:
Net loss	$ (14,443)	$ (12,501)	$ (13,209)	$ (13,073)	$ (26,944)	$ (26,282)
Weighted average common shares outstanding - basic and dilutive (in shares)	41,477		36,188		41,452	36,171
Net loss per common shares - basic and diluted (in dollars per share)	$ (0.35)		$ (0.37)		$ (0.65)	$ (0.73)
Anti-dilutive securities
Total (in shares)	6,325		5,017		6,325	5,017
Stock options outstanding
Anti-dilutive securities
Total (in shares)	5,690		4,818		5,690	4,818
Restricted stock units
Anti-dilutive securities
Total (in shares)	635		199		635	199

Cash, Cash Equivalents and Av_2

Cash, Cash Equivalents and Available for Sale Securities - Narrative (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Cash and cash equivalents	$ 106,889,000	$ 131,201,000
Cash	2,300,000	4,400,000
Investments in money market funds, U.S. Treasury securities and certain short-term investment-grade corporate debt securities with original maturities of 90 days or less	104,600,000	126,800,000
Available for sale securities	$ 0	$ 0

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Details) - USD ($) $ in Thousands	Jan. 01, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Stock options
Stock Option and Compensation Plans
Unrecognized share-based compensation costs for option awards, net of estimated forfeitures		$ 6,400		$ 6,400
Expected weighted average period to recognize share-based compensation costs				1 year 9 months 18 days
Restricted stock units
Stock Option and Compensation Plans
Expected weighted average period to recognize share-based compensation costs				1 year 6 months
Unrecognized compensation costs, net of estimated forfeitures		$ 2,100		$ 2,100
ESPP
Stock Option and Compensation Plans
Common stock issued (in shares)		0	0	31,522	12,229
Proceeds from stock plans		$ 41	$ 27
2013 Plan
Stock Option and Compensation Plans
Increase in number of shares available under the Plan (in shares)	1,656,000			8,554,000
Annual increase in shares reserved for issuance under the Plan (as a percent)	4.00%
Number of shares of common stock available for issuance under the Plan (in shares)		2,704,000		2,704,000
2013 Plan | ESPP
Stock Option and Compensation Plans
Number of shares available for future purchase (in shares)		920,707		920,707

Share-Based Compensation - Summ

Share-Based Compensation - Summary of Share-Based Compensation Expense by Award Type (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 2,207	$ 2,662	$ 4,677	$ 5,744
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	1,488	1,836	3,110	3,968
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	709	819	1,530	1,765
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 10	$ 7	$ 37	$ 11

Share-Based Compensation - Su_2

Share-Based Compensation - Summary of Share-Based Compensation Expense by Financial Statement Line (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 2,207	$ 2,662	$ 4,677	$ 5,744
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	989	1,106	2,159	2,546
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 1,218	$ 1,556	$ 2,518	$ 3,198

Share-Based Compensation - Su_3

Share-Based Compensation - Summary of Stock Option Activity (Details) shares in Thousands	6 Months Ended
	Jun. 30, 2019$ / sharesshares
Number of Shares Underlying Options
Outstanding at beginning of year (in shares) | shares	5,903
Granted (in shares) | shares	137
Forfeited (in shares) | shares	(261)
Expired (in shares) | shares	(89)
Outstanding at end of year (in shares) | shares	5,690
Vested and exercisable, June 30, 2019 (in shares) | shares	2,850
Vested and expected to vest, June 30. 2019 (in shares) | shares	5,463
Weighted Average Exercise Price
Outstanding at beginning of year (in dollars per share) | $ / shares	$ 13.72
Granted (in dollars per share) | $ / shares	1.35
Forfeited (in dollars per share) | $ / shares	26.18
Expired (in dollars per share) | $ / shares	12.72
Outstanding at end of year (in dollars per share) | $ / shares	12.89
Vested and exercisable, June 30, 2019 (in dollars per share) | $ / shares	21.83
Vested and expected to vest, June 30. 2019 (in dollars per share) | $ / shares	$ 13.26

Share-Based Compensation - Su_4

Share-Based Compensation - Summary of Outstanding RSU Awards Granted (Details) - Restricted stock units shares in Thousands	6 Months Ended
	Jun. 30, 2019$ / sharesshares
Restricted Stock Units
Outstanding, beginning of period (in shares) | shares	679
Awarded (in shares) | shares	10
Vested (in shares) | shares	(49)
Forfeited (in shares) | shares	(5)
Outstanding, end of period (in shares) | shares	635
Expected to vest (in shares) | shares	518
Weighted Average Grant-Date Fair Value
Outstanding, beginning of period (in dollars per share) | $ / shares	$ 15.61
Awarded (in dollars per share) | $ / shares	1.38
Vested (in dollars per share) | $ / shares	52.83
Forfeited (in dollars per share) | $ / shares	38.98
Outstanding, end of period (in dollars per share) | $ / shares	12.40
Expected to vest (in dollars per share) | $ / shares	$ 6.58

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income tax benefit	$ (4)	$ 1,037	$ (9)	$ 838

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Fair Value Measurements
Investments in investment-grade corporate debt securities	$ 0	$ 0
Transfer of assets from Level 1 to Level 2 of the fair value measurement hierarchy	0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Money market funds
Fair Value Measurements
Investments in money market funds	87,572,000	97,402,000
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Corporate debt securities
Fair Value Measurements
Investments in investment-grade corporate debt securities	0	0
Recurring basis | Significant other observable inputs (Level 2) | Money market funds
Fair Value Measurements
Investments in money market funds	0	0
Recurring basis | Significant other observable inputs (Level 2) | Corporate debt securities
Fair Value Measurements
Investments in investment-grade corporate debt securities	17,031,000	29,425,000
Recurring basis | Significant unobservable inputs (Level 3) | Money market funds
Fair Value Measurements
Investments in money market funds	0	0
Recurring basis | Significant unobservable inputs (Level 3) | Corporate debt securities
Fair Value Measurements
Investments in investment-grade corporate debt securities	$ 0	$ 0

Operating Leases - Narrative (D

Operating Leases - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset, net	$ 989	$ 989
Operating lease liability	989	989
Estimated incremental borrowing rate			6.00%
Lease and rent expense	300	600
Operating lease, payments	$ 300	$ 600
Weighted average remaining lease term	1 year	1 year
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset, net			$ 1,500
Operating lease liability			$ 1,500

Operating Leases - Schedule of

Operating Leases - Schedule of Operating Lease Liability Maturity (Details) $ in Thousands	Jun. 30, 2019USD ($)
Leases [Abstract]
Remainder of 2019	$ 520
2020	504
Total remaining obligation	1,024
Less imputed interest	(35)
Present value of lease liabilities	$ 989

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) shares in Millions, $ in Millions	Mar. 12, 2019USD ($)	Oct. 30, 2018USD ($)shares	May 31, 2019USD ($)licensed_product	Jun. 30, 2018USD ($)	Sep. 30, 2011USD ($)
Commitments and contingencies
Number of licensed products | licensed_product			1
Fees and costs paid to plaintiff's counsel	$ 0.3
License Agreements | Archemix | C5 Licensed Product | Achievement of specified clinical and regulatory milestones | Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone					$ 57.5
License Agreements | Archemix | C5 Licensed Product | First indication | Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone					30.5
License Agreements | Archemix | C5 Licensed Product | Second and third indication | Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone					24.5
License Agreements | Archemix | C5 Licensed Product | Sustained delivery applications | Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone					2.5
License Agreements | Archemix | C5 Licensed Product | Achievement of specified commercial milestones | Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone					$ 22.5
RHO-adRP License Agreement | University of Florida Research Foundation (UFRF) | Specified clinical, marketing approval and reimbursement approval milestones with respect to a licensed product
Commitments and contingencies
Amount to be paid on achievement of milestone				$ 23.5
RHO-adRP License Agreement | University of Florida Research Foundation (UFRF) | Specified commercial sales milestones with respect to a licensed product
Commitments and contingencies
Amount to be paid on achievement of milestone				$ 70
Inception 4
Commitments and contingencies
Contingent consideration arrangements, maximum amount		$ 105
Contingent consideration arrangements, maximum amount | shares		7.2
Contingent consideration arrangements, contingently issuable shares as a percentage of shares outstanding		19.90%
Inception 4 | GA Product
Commitments and contingencies
Clinical and marketing approval milestones		$ 45
Inception 4 | Wet AMD Product
Commitments and contingencies
Clinical and marketing approval milestones		$ 60
Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Primary Licensed Product | Specified clinical, marketing approval and reimbursement approval milestones with respect to a licensed product
Commitments and contingencies
Payments for license fees			$ 15.7
Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Primary Licensed Product | Specified commercial sales milestones with respect to a licensed product
Commitments and contingencies
Payments for license fees			48
Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Other Licensed Product | Specified clinical, marketing approval and reimbursement approval milestones with respect to a licensed product
Commitments and contingencies
Payments for license fees			3.1
Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Other Licensed Product | Specified commercial sales milestones with respect to a licensed product
Commitments and contingencies
Payments for license fees			$ 9.6

Subsequent Event - Narrative (D

Subsequent Event - Narrative (Details) - miniCEP290 License Agreement - University Of Massachusetts (UMass) - Subsequent Event $ / shares in Units, $ in Thousands	Jul. 22, 2019USD ($)$ / sharesshares
Subsequent Event [Line Items]
Payments for license fees	$ 400
Shares issued (in shares) | shares	75,000
Shares issued price (usd per share) | $ / shares	$ 0.001
Achievement of specified clinical and regulatory milestones
Subsequent Event [Line Items]
Amount to be paid on achievement of milestone	$ 14,750
Shares to be issued upon achievement of milestone | shares	75,000
Achievement of specified commercial milestones
Subsequent Event [Line Items]
Amount to be paid on achievement of milestone	$ 48,000