IVERIC bio (ISEE) 10-Q 6 Aug 20 2020 Q2 Quarterly report Financial data

Cover

Cover - shares	6 Months Ended
	Jun. 30, 2020	Aug. 03, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	001-36080
Entity Registrant Name	IVERIC bio, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8185347
Entity Address, Address Line One	One Penn Plaza,
Entity Address, Address Line Two	35th Floor
Entity Address, City or Town	New York,
Entity Address, State or Province	NY
Entity Address, Postal Zip Code	10119
City Area Code	212
Local Phone Number	845-8200
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	ISEE
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	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)		89,502,223
Entity Central Index Key	0001410939
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2

Unaudited Consolidated Balance

Unaudited Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 245,735	$ 125,699
Prepaid expenses and other current assets	2,198	2,043
Income tax receivable	1,764	882
Total current assets	249,697	128,624
Property and equipment, net	97	173
Right-of-use asset, net	144	496
Income tax receivable, non-current	0	882
Other assets	12	12
Total assets	249,950	130,187
Current liabilities
Accrued research and development expenses	7,131	6,860
Accounts payable and accrued expenses	4,634	5,629
Lease liability	53	495
Total current liabilities	11,818	12,984
Lease liability, non-current	91	0
Total liabilities	11,909	12,984
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, 89,488,531 and 49,627,064 shares issued and outstanding at June 30, 2020 and December 31, 2019, respectively	89	50
Additional paid-in capital	752,143	597,679
Accumulated deficit	(514,191)	(480,526)
Total stockholders' equity	238,041	117,203
Total liabilities and stockholders' equity	$ 249,950	$ 130,187

Unaudited Consolidated Balanc_2

Unaudited Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
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)	89,488,531	49,627,064
Common stock, shares outstanding (in shares)	89,488,531	49,627,064

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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Operating expenses:
Research and development	$ 12,720	$ 10,009	$ 26,470	$ 17,694
General and administrative	6,289	5,198	11,287	10,679
Total operating expenses	19,009	15,207	37,757	28,373
Loss from operations	(19,009)	(15,207)	(37,757)	(28,373)
Interest income	46	617	404	1,287
Other income (expense)	(12)	151	(7)	151
Loss before income tax provision (benefit)	(18,975)	(14,439)	(37,360)	(26,935)
Income tax provision (benefit)	(386)	4	(3,695)	9
Net loss	(18,589)	(14,443)	(33,665)	(26,944)
Comprehensive loss	$ (18,589)	$ (14,443)	$ (33,665)	$ (26,944)
Net loss per common share:
Basic and diluted (in dollars per share)	$ (0.32)	$ (0.35)	$ (0.61)	$ (0.65)
Weighted average common shares outstanding:
Basic and diluted (in shares)	57,421	41,477	55,424	41,452

Unaudited Consolidated Statem_2

Unaudited Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Underwritten Offering	Private Placement	Preferred Stock	Common Stock	Common StockUnderwritten Offering	Common StockPrivate Placement	Additional paid-in capital	Additional paid-in capitalUnderwritten Offering	Additional paid-in capitalPrivate Placement	Accumulated Deficit
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 plan (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 plan (in shares)					24
Issuance of common stock under employee stock compensation plans	0							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)
Balance at beginning of period (in shares) at Dec. 31, 2019				0	49,627
Balance at beginning of period at Dec. 31, 2019	117,203			$ 0	$ 50			597,679			(480,526)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plan (in shares)					105
Issuance of common stock under employee stock compensation plans	179							179
Share-based compensation	2,324							2,324
Net loss	(15,076)										(15,076)
Balance at end of period (in shares) at Mar. 31, 2020				0	49,732
Balance at end of period at Mar. 31, 2020	104,630			$ 0	$ 50			600,182			(495,602)
Balance at beginning of period (in shares) at Dec. 31, 2019				0	49,627
Balance at beginning of period at Dec. 31, 2019	117,203			$ 0	$ 50			597,679			(480,526)
Increase (Decrease) in Stockholders' Equity
Net loss	(33,665)
Balance at end of period (in shares) at Jun. 30, 2020				0	89,489
Balance at end of period at Jun. 30, 2020	238,041			$ 0	$ 89			752,143			(514,191)
Balance at beginning of period (in shares) at Mar. 31, 2020				0	49,732
Balance at beginning of period at Mar. 31, 2020	104,630			$ 0	$ 50			600,182			(495,602)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net of issuance costs (in shares)						28,503	8,649
Issuance of common stock, net of issuance costs		$ 116,883	$ 33,237			$ 28	$ 9		$ 116,855	$ 33,228
Issuance of common stock under the exercise of pre-funded warrants (in shares)					2,500
Issuance of common stock under the exercise of pre-funded warrants	0				$ 2			(2)
Issuance of common stock under employee stock compensation plan (in shares)					105
Issuance of common stock under employee stock compensation plans	7							7
Share-based compensation	1,873							1,873
Net loss	(18,589)										(18,589)
Balance at end of period (in shares) at Jun. 30, 2020				0	89,489
Balance at end of period at Jun. 30, 2020	$ 238,041			$ 0	$ 89			$ 752,143			$ (514,191)

Unaudited Consolidated Statem_3

Unaudited Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating Activities
Net loss	$ (33,665)	$ (26,944)
Adjustments to reconcile net loss to net cash used in operating activities
Depreciation and other expense	77	83
Gain on sale of property and equipment	0	(150)
Deferred income taxes	0	0
Share-based compensation	4,197	4,677
Changes in operating assets and liabilities:
Income tax receivable	0	(1)
Prepaid expense and other assets	(155)	302
Accrued research and development expenses	271	308
Accounts payable and accrued expenses	(995)	(2,628)
Net cash used in operating activities	(30,270)	(24,353)
Investing Activities
Net cash provided by (used in) investing activities	0	0
Financing Activities
Proceeds from employee stock plan purchases	186	41
Proceeds from issuance of common stock	150,100
Net cash provided by financing activities	150,306	41
Net change in cash and cash equivalents	120,036	(24,312)
Cash and cash equivalents
Beginning of period	125,699	131,201
End of period	245,735	106,889
Supplemental disclosure of cash paid
Income tax refunds received	3,327	0
Underwritten Offering
Financing Activities
Proceeds from issuance of common stock	116,883	0
Private Placement
Financing Activities
Proceeds from issuance of common stock	$ 33,237	$ 0

Business

Business	6 Months Ended
	Jun. 30, 2020
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 focused on the discovery and development of novel treatment options for retinal diseases with significant unmet medical needs. The Company is currently developing both therapeutic product candidates for age-related retinal diseases and gene therapy product candidates for orphan inherited retinal diseases ("IRDs"). The Company's therapeutics portfolio consists of its clinical stage product candidate Zimura® (avacincaptad pegol), a complement C5 inhibitor, and IC-500, its preclinical product candidate from its High temperature requirement A serine peptidase 1 protein ("HtrA1") inhibitors program. The Company is currently targeting the following diseases with Zimura: • geographic atrophy ("GA"), which is the advanced stage of age-related macular degeneration ("AMD") and is characterized by marked thinning or atrophy of retinal tissue, leading to irreversible loss of vision; and • autosomal recessive Stargardt disease ("STGD1"), which is characterized by progressive damage to the central portion of the retina (the "macula") and other retinal tissue of young adults, leading to loss of vision. In June 2020, the Company announced 18-month data from its international, randomized, double masked, sham controlled, multi-center Phase 3 clinical trial (the "GATHER1 trial") assessing the safety and efficacy of Zimura for the treatment of GA secondary to AMD. 286 patients were enrolled in this trial across multiple treatment groups, including various Zimura doses and sham control groups and patients were treated and followed for 18 months. The 18-month data supports the previously announced 12-month data from this trial, which confirmed that Zimura met the prespecified primary efficacy endpoint in reducing the rate of GA growth with statistical significance. The reduction in the mean rate of GA growth over 18 months was 28.11% for the Zimura 2 mg group as compared to the corresponding sham control group and 29.97% for the Zimura 4 mg group as compared to the corresponding sham control group. The pre-specified efficacy analysis for the primary endpoint was performed at month 12 using all of the statistical power in the trial to detect a statistically significant difference. Therefore, the p-values for the 18 month statistical analyses are descriptive in nature. The descriptive p-values for the treatment effects at month 18 were p=0.0014 for the Zimura 2 mg group and p=0.0021 for the Zimura 4 mg group. In this trial, the treatment effect was observed as early as 6 months, with an increase in the absolute difference of the mean change in GA growth for treatment with either Zimura 2 mg or Zimura 4 mg, as compared to sham, at each subsequent time point, suggesting the progressive benefit of continuous treatment with Zimura. Zimura maintained its favorable safety profile at 18 months with no investigator reported Zimura related adverse events, no cases of endophthalmitis and a lower rate of choroidal neovascularization ("CNV") than reported for C3 inhibition. The overall 18 month data may suggest a dose response relationship. GATHER1 was designed to be a Phase 2b screening trial, with the potential to qualify as a pivotal trial depending on the magnitude and statistical significance of the potential benefit observed. Based on the 12-month data, the Company believes that the GATHER1 trial qualifies as the first of two Phase 3 trials typically required by the U.S. Food and Drug Administration ("FDA") for marketing approval of a pharmaceutical product. In light of the 12-month data, the Company changed the phase designation of the GATHER1 trial to a Phase 2/3 trial and believes it counts as a Phase 3 clinical trial. In June 2020, the Company dosed the first patient in its second international, randomized, double masked, sham controlled, multi-center Phase 3 clinical trial of Zimura for the treatment of GA secondary to AMD (the "GATHER2 trial"). The Company plans to enroll approximately 400 patients in this trial. The Company recently reopened enrollment in its ongoing, international, randomized, double masked, sham controlled, multi-center Phase 2b clinical trial evaluating the safety and efficacy of Zimura for the treatment of STGD1 (the "OPH2005 trial"). The Company plans to enroll approximately 25 additional patients, with the goal of enrolling a total of approximately 120 patients as was initially intended in the protocol for the OPH2005 trial. The Company is developing IC-500 for GA and potentially other age-related retinal diseases. The Company's gene therapy portfolio consists of two product candidates in preclinical development and several ongoing collaborative sponsored research programs, each of which uses adeno-associated virus ("AAV") for gene delivery. These AAV mediated 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, or Best disease, which is generally characterized by bilateral egg yolk-like lesions in the macula, which, 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; and • IRDs associated with mutations in the USH2A gene, which include Usher syndrome type 2A and USH2A-associated non-syndromic autosomal recessive retinitis pigmentosa. The Company's lead gene therapy product candidate is IC-100, which it is developing for the treatment of RHO-adRP. Subject to successful completion of preclinical development and manufacturing under current good manufacturing practices ("cGMP"), the Company plans to file an investigational new drug application ("IND") for IC-100 by the end of 2020 or early 2021 with the goal of commencing patient enrollment in a Phase 1/2 clinical trial during the first half of 2021. The Company is also developing IC-200, its gene therapy product candidate for the treatment of IRDs associated with mutations in the BEST1 gene. Subject to successful completion of preclinical development and manufacturing under cGMP, the Company plans to file an IND and, subject to regulatory review, initiate a Phase 1/2 clinical trial for IC-200 in 2021.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2020
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 (“Annual Report”) for the year ended December 31, 2019 filed with the Securities and Exchange Commission ("SEC") on February 27, 2020. Basis of Presentation and Consolidation In the opinion of management, the Company’s condensed consolidated financial statements include all adjustments, consisting of normal recurring accruals, necessary for a fair statement of the Company’s financial statements for interim periods in accordance with accounting principles generally accepted in the United States (U.S. GAAP). The consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The information included in this quarterly report on Form 10-Q should be read in conjunction with the Company’s audited consolidated financial statements and the accompanying notes included in the Annual Report. The year-end condensed consolidated balance sheet data presented for comparative purposes was derived from the Company’s audited financial statements but does not include all disclosures required by U.S. GAAP. The results of operations for the three and six months ended June 30, 2020 are not necessarily indicative of the operating results for the full year or for any other subsequent interim period. 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, 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, 2020, the Company had cash and cash equivalents of approximately $245.7 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. The Company believes it is not exposed to significant credit risk on its cash and cash equivalents. Concentration of Suppliers The Company has historically relied on a single third-party manufacturer to provide the drug substance for Zimura on a purchase order basis. The Company also has historically relied on 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 on a purchase order basis the proprietary polyethylene glycol starting material used to manufacture Zimura. 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 Zimura. The Company currently relies exclusively upon a single third-party contract manufacturer for IC-100 and IC-200 and also relies on sole-source suppliers for certain starting materials used in the manufacture of such product candidates. The Company currently relies upon a single third-party contract manufacturer to conduct process development, scale-up and cGMP manufacture of IC-500 for potential preclinical toxicology studies and clinical trials. 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, different business objectives, financial difficulties, insolvency or the COVID-19 pandemic, 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. Accounting Standards Codification, or 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 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 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. Leases The Company has leased its office spaces 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. Pursuant to ASC 842, Leases, the Company records 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. 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 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 and analysis 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 collaborators. All research and development expenses are charged to operations as incurred in accordance with ASC 730, Research and Development . The Company accounts for non-refundable advance payments for goods and services that will be used in future research and development activities as expenses when the service has been performed or when the goods have been received, rather than when the payment is made. 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 and consultants, 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. The Company estimates forfeitures at the time of grant and revises those estimates in subsequent periods if actual forfeitures differ from its estimates. The Company uses historical data to estimate pre-vesting forfeitures and record share-based compensation expense only for those awards that are expected to vest. To the extent that actual forfeitures differ from the Company's estimates, the difference is recorded as a cumulative adjustment in the period the estimates were revised. Stock Options The Company estimates the fair value of stock options granted to employees, non-employee directors and consultants on the date of grant using the Black-Scholes option-pricing model. The Company's computation of stock-price volatility is based on daily historical volatility during the time period that corresponds to the expected option term. The Company's computation of expected term is determined using the expected term of stock option grants to employees based on an analysis of actual option exercises. 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 month periods ended June 30, 2020 and 2019: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Expected common stock price volatility 118% 88% 117% 87% Risk-free interest rate 0.26%-0.36% 2.15%-2.31% 0.26%-1.34% 2.15%-2.54% Expected term of options (years) 4.5 5.3 4.5 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 Company's board of directors adopted the ESPP pursuant to which the Company may sell up to an aggregate of 1,000,000 shares of its 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 June 2016, the Financial Accounting Standards Board (the "FASB") issued Accounting Standard Update ("ASU") 2016-13 “Financial Instruments (Topic 326) Measurement of Credit Losses on Financial Instrument" (“CECL”). ASU 2016-13 requires an allowance for expected credit losses on financial assets be recognized as early as day one of the instrument. This ASU departs from the incurred loss model which means the probability threshold is removed. It considers more forward-looking information and requires the entity to estimate its credit losses as far as it can reasonably estimate. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company adopted this accounting standard effective January 1, 2020 with no material impact to its financial statements. 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 became effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. The Company adopted this accounting standard effective January 1, 2020 with no material impact to its financial statements. 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 became effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years. The Company adopted this accounting standard effective January 1, 2020 with no material impact to its 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 became effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. The Company adopted this accounting standard effective January 1, 2020 with no material impact to its financial statements. Recent Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes, eliminates certain exceptions within ASC 740, Income Taxes , and clarifies certain aspects of the current guidance to promote consistency among reporting entities. ASU 2019-12 is effective for fiscal years beginning after December 15, 2021. Most amendments within the standard are required to be applied on a prospective basis, while certain amendments must be applied on a retrospective or modified retrospective basis. The Company is evaluating the effects, if any, of the adoption of ASU 2019-12 guidance on the Company’s financial position, results of operations and cash flows

Common Stock

Common Stock	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Common Stock	Common Stock In June 2020, the Company completed an underwritten public offering in which the Company sold 28,503,220 shares of its common stock, which includes the exercise in full of the underwriters’ option to purchase additional shares of the Company’s common stock, at a price to the public of $4.100 per share and at a price to the underwriters of $3.854 per share. The Company also sold to certain investors in lieu of common stock, pre-funded warrants to purchase 1,914,280 shares of its common stock at a price to the public of $4.099 per share underlying each pre-funded warrant, and at a price to the underwriters of $3.853 per share underlying each pre-funded warrant. Concurrently with the June 2020 public offering, the Company completed a private placement in which the Company sold 8,649,453 shares of its common stock to affiliates of Vivo Capital, LLC and Samsara BioCapital, LP, at a sale price equal to the price to the public in the underwritten public offering. The net proceeds from the public offering and private placement, after deducting underwriting discounts, underwriting and placement agent commissions and other expenses totaling $10.1 million, was approximately $150.1 million. The Company evaluated the pre-funded warrants for liability or equity classification in accordance with the provisions of ASC 480, Distinguishing Liabilities from Equity , and ASC 815-40, Derivatives and Hedging . Based on the provisions

Net Loss Per Common Share

Net Loss Per Common Share	6 Months Ended
	Jun. 30, 2020
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 and pre-funded warrants outstanding during the period. Basic and diluted shares outstanding includes the weighted average effect of the Company's outstanding pre-funded warrants as the exercise of such pre-funded warrants requires nominal consideration to be given for the delivery of the corresponding shares of common stock. As of June 30, 2020, the Company had 3,164,280 pre-funded warrants outstanding, which if exercised, would increase the number of shares of common stock issued and outstanding. For the periods when 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, 2020 2019 2020 2019 Basic and diluted net loss per common share calculation: Net loss $ (18,589) $ (14,443) $ (33,665) $ (26,944) Weighted average common shares outstanding - basic and dilutive 57,421 41,477 55,424 41,452 Net loss per share of common stock - basic and diluted $ (0.32) $ (0.35) $ (0.61) $ (0.65) 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, 2020 2019 2020 2019 Stock options outstanding 7,155 5,690 7,155 5,690 Restricted stock units 1,636 635 1,636 635 Total 8,791 6,325 8,791 6,325

Cash and Cash Equivalents

Cash and Cash Equivalents	6 Months Ended
	Jun. 30, 2020
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Cash and Cash Equivalents	Cash and Cash Equivalents 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, 2020 and December 31, 2019, the Company had cash and cash equivalents of approximately $245.7 million and $125.7 million, respectively. Cash and cash equivalents included cash of $3.4 million at June 30, 2020 and $3.2 million at December 31, 2019. Cash and cash equivalents at June 30, 2020 and December 31, 2019 included $242.4 million and $122.5 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, 2020 or at December 31, 2019, respectively. The Company believes that its existing cash and cash equivalents as of June 30, 2020 will be sufficient to fund its currently planned capital expenditure requirements and operating expenses for at least the next 12 months from the filing of this Quarterly Report on Form 10-Q. This estimate is based on the Company's current business plan, which includes the continuation of its clinical development programs for Zimura, the progression of its IC-100 and IC-200 programs into the clinic, and the advancement of its IC-500 development program. This estimate assumes that it will enroll approximately 400 patients in the GATHER2 trial. This estimate does not reflect any additional expenditures resulting from the potential in-licensing or acquisition of additional product candidates or technologies, commencement of any new sponsored research programs or any associated development the Company may pursue. The Company has based this estimate on assumptions that may prove to be wrong, and it could use its available capital resources sooner than it currently expects.

Share-Based Compensation

Share-Based Compensation	6 Months Ended
	Jun. 30, 2020
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 10,539,000 additional shares to the 2013 Plan, including for 2020, an increase of approximately 1,985,000 shares, or approximately 4% of the total number of shares of the Company's common stock outstanding as of January 1, 2020. As of June 30, 2020, the Company had approximately 2,774,000 shares available for grant under the 2013 Plan. In October 2019, the Company's board of directors adopted its 2019 Inducement Stock Incentive Plan (the “2019 Inducement Plan”) to reserve initially 1,000,000 shares of its common stock to be used exclusively for grants of awards to individuals who were not previously employees or directors of the Company as a material inducement to such individuals’ entry into employment with the Company within Rule 5635(c)(4) of the Nasdaq Listing Rules. The terms and conditions of the 2019 Inducement Plan are substantially similar to those of the 2013 Plan. In March 2020, the Company's board of directors amended the 2019 Inducement Plan to reserve an additional 1,000,000 shares of its common stock for issuance under the plan. As of June 30, 2020, the Company had approximately 897,000 shares available for grant under the 2019 Inducement 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, 2020 2019 2020 2019 Stock options $ 1,093 $ 1,488 $ 2,467 $ 3,110 Restricted stock units 752 709 1,688 1,530 Employee stock purchase plan 28 10 42 37 Total $ 1,873 $ 2,207 $ 4,197 $ 4,677 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, 2020 2019 2020 2019 Research and development $ 951 $ 989 $ 2,104 $ 2,159 General and administrative 922 1,218 2,093 2,518 Total $ 1,873 $ 2,207 $ 4,197 $ 4,677 Stock Options A summary of the stock option activity, weighted average exercise prices, options outstanding, exercisable and expected to vest as of June 30, 2020 is as follows (in thousands except weighted average exercise price): Number of Shares Underlying Options Weighted Outstanding, December 31, 2019 6,780 $ 10.89 Granted 696 $ 3.87 Exercised (54) $ 2.65 Forfeited (260) $ 15.59 Expired (7) $ 1.59 Outstanding, June 30, 2020 7,155 $ 10.11 Vested and exercisable, June 30, 2020 3,720 $ 16.19 Vested and expected to vest, June 30, 2020 6,845 $ 10.41 As of June 30, 2020, there were approximately $7.3 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 2.7 years. RSUs The following table presents a summary of the Company's outstanding RSU awards granted as of June 30, 2020 (in thousands except weighted average grant-date fair value): Restricted Weighted Average Outstanding, December 31, 2019 1,481 $ 7.79 Awarded 362 $ 3.61 Vested (112) $ 18.72 Forfeited (95) $ 5.39 Outstanding, June 30, 2020 1,636 $ 6.26 Outstanding, Expected to vest 1,430 $ 4.10 As of June 30, 2020, there were approximately $4.4 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 2.6 years. ESPP As of June 30, 2020, there were 838,182 shares available for future purchases under the ESPP. There were no shares issued under the ESPP during the three months ended June 30, 2020 and 2019. There were 43,581 shares of common stock issued under the ESPP during the six months ended June 30, 2020. Cash proceeds from ESPP purchases were $42 thousand during the six months ended June 30, 2020. 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.

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the three and six months ended June 30, 2020, the Company recorded a benefit for income taxes of $0.4 million and $3.7 million, respectively. The income tax benefit for the three and six months ended June 30, 2020 was to reflect a settlement of a local tax audit and the associated decrease in the Company's related uncertain tax position, including interest and penalties. For the three and six months ended June 30, 2019, the Company recorded a de minimis provision for income taxes. In response to the COVID-19 pandemic, the U.S. Congress enacted the Coronavirus Aid, Relief, and Economic Security Act ("CARES Act") on March 27, 2020. The CARES Act provides numerous tax provisions and other stimulus measures, including the immediate refund of minimum tax credits. The Company has recorded a current tax receivable of approximately $1.8 million in anticipation of this refund. 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, 2020
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, 2020: Fair Value Measurement Using Quoted prices in Significant other Significant Assets Investments in money market funds* $ 242,354 $ — $ — 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, 2019: Fair Value Measurement Using Quoted prices in Significant other Significant Assets Investments in money market funds* $ 108,585 $ — $ — Investments in corporate debt securities* $ — $ 13,875 $ — * 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, 2020.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Zimura - Archemix Corp. The Company is party to an agreement with Archemix Corp. ("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 $56.5 million if the Company achieves specified development, clinical and regulatory milestones, with $30.5 million of such payments relating to a first indication, $23.5 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 the University of Florida Research Foundation, Incorporated ("UFRF") and the University of Pennsylvania ("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 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. miniCEP290 Program - University of Massachusetts Under its exclusive license agreement with the University of Massachusetts ("UMass") for its miniCEP290 program, which targets LCA10, which is associated with mutations in the CEP290 gene, the Company is obligated to pay UMass up to an aggregate of $14.75 million in cash and issue up to 75,000 shares of common stock of the Company if the Company achieves specified clinical and regulatory milestones with respect to a licensed product. In addition, the Company is obligated 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. 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 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 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 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. IC-500 and Other HtrA1 Inhibitors - Former Equityholders of Inception 4 Under the agreement and plan of merger between the Company and Inception 4, Inc. ("Inception 4"), pursuant to which the Company acquired Inception 4 and its HtrA1 inhibitor program (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. On September 18, 2019, the court issued an order dismissing some, but not all, of the allegations in the CAC. On November 18, 2019, the Company and the individual defendants filed an answer to the complaint. On June 12, 2020, the lead plaintiff filed a motion for class certification. The Company's response is due August 11, 2020. This case is currently in the discovery phase. 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. On September 19, 2019, the court denied the Company's motion to dismiss this complaint. This matter was subsequently referred to a special litigation committee of the Company's board of directors. On February 18, 2020, the Company filed an answer to the complaint. The Company and the plaintiff agreed to stay this litigation while the special litigation committee conducts its investigation. On May 5, 2020, the court approved the stipulation and stayed the litigation through November 1, 2020. 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. These shareholder demands have been referred to a demand review committee of the Company's board of directors. The Company has entered into tolling agreements with the directors named in the demands. 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.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies - (Policies)	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	In the opinion of management, the Company’s condensed consolidated financial statements include all adjustments, consisting of normal recurring accruals, necessary for a fair statement of the Company’s financial statements for interim periods in accordance with accounting principles generally accepted in the United States (U.S. GAAP).
Consolidation	The consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The information included in this quarterly report on Form 10-Q should be read in conjunction with the Company’s audited consolidated financial statements and the accompanying notes included in the Annual Report.The year-end condensed consolidated balance sheet data presented for comparative purposes was derived from the Company’s audited financial statements but does not include all disclosures required by U.S. GAAP. The results of operations for the three and six months ended June 30, 2020 are not necessarily indicative of the operating results for the full year or for any other subsequent interim period.
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, 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. The Company believes it is not exposed to significant credit risk on its cash and cash equivalents.
Concentration of Suppliers	Concentration of Suppliers The Company has historically relied on a single third-party manufacturer to provide the drug substance for Zimura on a purchase order basis. The Company also has historically relied on 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 on a purchase order basis the proprietary polyethylene glycol starting material used to manufacture Zimura. 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 Zimura. The Company currently relies exclusively upon a single third-party contract manufacturer for IC-100 and IC-200 and also relies on sole-source suppliers for certain starting materials used in the manufacture of such product candidates. The Company currently relies upon a single third-party contract manufacturer to conduct process development, scale-up and cGMP manufacture of IC-500 for potential preclinical toxicology studies and clinical trials. 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, different business objectives, financial difficulties, insolvency or the COVID-19 pandemic, 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. Accounting Standards Codification, or 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 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 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.
Leases	Leases The Company has leased its office spaces 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. Pursuant to ASC 842, Leases, the Company records 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.
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
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 and analysis 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 collaborators. All research and development expenses are charged to operations as incurred in accordance with ASC 730, Research and Development . The Company accounts for non-refundable advance payments for goods and services that will be used in future research and development activities as expenses when the service has been performed or when the goods have been received, rather than when the payment is made.
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 and consultants, 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. The Company estimates forfeitures at the time of grant and revises those estimates in subsequent periods if actual forfeitures differ from its estimates. The Company uses historical data to estimate pre-vesting forfeitures and record share-based compensation expense only for those awards that are expected to vest. To the extent that actual forfeitures differ from the Company's estimates, the difference is recorded as a cumulative adjustment in the period the estimates were revised. Stock Options The Company estimates the fair value of stock options granted to employees, non-employee directors and consultants on the date of grant using the Black-Scholes option-pricing model. The Company's computation of stock-price volatility is based on daily historical volatility during the time period that corresponds to the expected option term. The Company's computation of expected term is determined using the expected term of stock option grants to employees based on an analysis of actual option exercises. 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 month periods ended June 30, 2020 and 2019: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Expected common stock price volatility 118% 88% 117% 87% Risk-free interest rate 0.26%-0.36% 2.15%-2.31% 0.26%-1.34% 2.15%-2.54% Expected term of options (years) 4.5 5.3 4.5 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 Company's board of directors adopted the ESPP pursuant to which the Company may sell up to an aggregate of 1,000,000 shares of its 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 June 2016, the Financial Accounting Standards Board (the "FASB") issued Accounting Standard Update ("ASU") 2016-13 “Financial Instruments (Topic 326) Measurement of Credit Losses on Financial Instrument" (“CECL”). ASU 2016-13 requires an allowance for expected credit losses on financial assets be recognized as early as day one of the instrument. This ASU departs from the incurred loss model which means the probability threshold is removed. It considers more forward-looking information and requires the entity to estimate its credit losses as far as it can reasonably estimate. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company adopted this accounting standard effective January 1, 2020 with no material impact to its financial statements. 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 became effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. The Company adopted this accounting standard effective January 1, 2020 with no material impact to its financial statements. 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 became effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years. The Company adopted this accounting standard effective January 1, 2020 with no material impact to its 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 became effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. The Company adopted this accounting standard effective January 1, 2020 with no material impact to its financial statements. Recent Accounting Pronouncements In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes (“ASU 2019-12”), which simplifies the accounting for income taxes, eliminates certain exceptions within ASC 740, Income Taxes , and clarifies certain aspects of the current guidance to promote consistency among reporting entities. ASU 2019-12 is effective for fiscal years beginning after December 15, 2021. Most amendments within the standard are required to be applied on a prospective basis, while certain amendments must be applied on a retrospective or modified retrospective basis. The Company is evaluating the effects, if any, of the adoption of ASU 2019-12 guidance on the Company’s financial position, results of operations and cash flows

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - (Tables)	6 Months Ended
	Jun. 30, 2020
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 month periods ended June 30, 2020 and 2019: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Expected common stock price volatility 118% 88% 117% 87% Risk-free interest rate 0.26%-0.36% 2.15%-2.31% 0.26%-1.34% 2.15%-2.54% Expected term of options (years) 4.5 5.3 4.5 5.6 Expected dividend yield — — — —

Net Loss Per Common Share - (Ta

Net Loss Per Common Share - (Tables)	6 Months Ended
	Jun. 30, 2020
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted net 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, 2020 2019 2020 2019 Basic and diluted net loss per common share calculation: Net loss $ (18,589) $ (14,443) $ (33,665) $ (26,944) Weighted average common shares outstanding - basic and dilutive 57,421 41,477 55,424 41,452 Net loss per share of common stock - basic and diluted $ (0.32) $ (0.35) $ (0.61) $ (0.65)
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, 2020 2019 2020 2019 Stock options outstanding 7,155 5,690 7,155 5,690 Restricted stock units 1,636 635 1,636 635 Total 8,791 6,325 8,791 6,325

Share-Based Compensation - (Tab

Share-Based Compensation - (Tables)	6 Months Ended
	Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Schedule of Allocation of Share-based Compensation Costs by Award Type	Stock-based compensation by award type was as follows: Three Months Ended June 30, Six Months Ended June 30, 2020 2019 2020 2019 Stock options $ 1,093 $ 1,488 $ 2,467 $ 3,110 Restricted stock units 752 709 1,688 1,530 Employee stock purchase plan 28 10 42 37 Total $ 1,873 $ 2,207 $ 4,197 $ 4,677
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, 2020 2019 2020 2019 Research and development $ 951 $ 989 $ 2,104 $ 2,159 General and administrative 922 1,218 2,093 2,518 Total $ 1,873 $ 2,207 $ 4,197 $ 4,677
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, 2020 is as follows (in thousands except weighted average exercise price): Number of Shares Underlying Options Weighted Outstanding, December 31, 2019 6,780 $ 10.89 Granted 696 $ 3.87 Exercised (54) $ 2.65 Forfeited (260) $ 15.59 Expired (7) $ 1.59 Outstanding, June 30, 2020 7,155 $ 10.11 Vested and exercisable, June 30, 2020 3,720 $ 16.19 Vested and expected to vest, June 30, 2020 6,845 $ 10.41
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, 2020 (in thousands except weighted average grant-date fair value): Restricted Weighted Average Outstanding, December 31, 2019 1,481 $ 7.79 Awarded 362 $ 3.61 Vested (112) $ 18.72 Forfeited (95) $ 5.39 Outstanding, June 30, 2020 1,636 $ 6.26 Outstanding, Expected to vest 1,430 $ 4.10

Fair Value Measurements - (Tabl

Fair Value Measurements - (Tables)	6 Months Ended
	Jun. 30, 2020
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, 2020: Fair Value Measurement Using Quoted prices in Significant other Significant Assets Investments in money market funds* $ 242,354 $ — $ — 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, 2019: Fair Value Measurement Using Quoted prices in Significant other Significant Assets Investments in money market funds* $ 108,585 $ — $ — Investments in corporate debt securities* $ — $ 13,875 $ — * 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.

Business - Narrative (Details)

Business - Narrative (Details)	Jun. 30, 2020patient
GATHER1 Trial
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of patients enrolled in trial	286
GATHER2 Trial
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of patients planned to enroll in trial	400
OPH2005 Trial
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of patients planned to enroll in trial	120
Number of additional patients planned to enroll in trial	25

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Segment and Geographic Information (Details)	6 Months Ended
	Jun. 30, 2020segment
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, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Cash and cash equivalents	$ 245,735	$ 125,699

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Property and Equipment (Details)	6 Months Ended
	Jun. 30, 2020
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, 2020	Apr. 30, 2016
Share-Based Compensation
Expected dividend yield	0.00%
Employee stock purchase plan | Maximum
Share-Based Compensation
Number of initial 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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
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	118.00%	88.00%	117.00%	87.00%
Risk-free interest rate, minimum	0.26%	2.15%	0.26%	2.15%
Risk-free interest rate, maximum	0.36%	2.31%	1.34%	2.54%
Expected term of options (years)	4 years 6 months	5 years 3 months 18 days	4 years 6 months	5 years 7 months 6 days
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Common Stock (Details)

Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2020	Jun. 30, 2019
Subsidiary, Sale of Stock [Line Items]
Warrants issued in transaction (in shares)	1,914,280
Pre-funded warrants outstanding (in shares)	3,164,280	3,164,280	3,164,280
Payments of stock issuance costs			$ 10,100
Proceeds from issuance of common stock			$ 150,100
Underwritten Offering
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares)		28,503,220
Sale of stock price (in dollars per share)	$ 4.100	$ 4.100	$ 4.100
Proceeds from issuance of common stock			$ 116,883	$ 0
Underwritten Offering, Underwriters
Subsidiary, Sale of Stock [Line Items]
Sale of stock price (in dollars per share)	$ 3.854	3.854	$ 3.854
Private Placement
Subsidiary, Sale of Stock [Line Items]
Number of shares issued in transaction (in shares)	8,649,453
Exercise price of pre-funded warrants (in dollars per share)	$ 4.099	4.099	$ 4.099
Proceeds from issuance of common stock			$ 33,237	$ 0
Private Placement, Underwriters
Subsidiary, Sale of Stock [Line Items]
Exercise price of pre-funded warrants (in dollars per share)	$ 3.853	$ 3.853	$ 3.853

Net Loss Per Common Share - Nar

Net Loss Per Common Share - Narrative (Details)	Jun. 30, 2020shares
Earnings Per Share [Abstract]
Pre-funded warrants outstanding (in shares)	3,164,280

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, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Basic and diluted net loss per common share calculation:
Net loss	$ (18,589)	$ (15,076)	$ (14,443)	$ (12,501)	$ (33,665)	$ (26,944)
Weighted average common shares outstanding - basic and dilutive (in shares)	57,421		41,477		55,424	41,452
Basic and diluted (in dollars per share)	$ (0.32)		$ (0.35)		$ (0.61)	$ (0.65)
Anti-dilutive securities
Total (in shares)	8,791		6,325		8,791	6,325
Stock options outstanding
Anti-dilutive securities
Total (in shares)	7,155		5,690		7,155	5,690
Restricted stock units
Anti-dilutive securities
Total (in shares)	1,636		635		1,636	635

Cash and Cash Equivalents - Nar

Cash and Cash Equivalents - Narrative (Details)	Jun. 30, 2020USD ($)patient	Dec. 31, 2019USD ($)
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 245,735,000	$ 125,699,000
Cash	3,400,000	3,200,000
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	242,400,000	122,500,000
Available for sale securities	$ 0	$ 0
GATHER2 Trial
Cash and Cash Equivalents [Line Items]
Number of patients planned to enroll in trial | patient	400

Share-Based Compensation - Narr

Share-Based Compensation - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended		90 Months Ended
	Mar. 31, 2020	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Oct. 31, 2019
Stock options
Stock Option and Compensation Plans
Unrecognized share-based compensation costs for option awards, net of estimated forfeitures		$ 7,300		$ 7,300		$ 7,300
Expected weighted average period to recognize share-based compensation costs (in years)				2 years 8 months 12 days
Restricted stock units
Stock Option and Compensation Plans
Expected weighted average period to recognize share-based compensation costs (in years)				2 years 7 months 6 days
Unrecognized compensation costs, net of estimated forfeitures		$ 4,400		$ 4,400		$ 4,400
Employee stock purchase plan
Stock Option and Compensation Plans
Common stock issued (in shares)		0	0	43,581	31,522
Proceeds from stock plans				$ 42	$ 41
2013 Plan
Stock Option and Compensation Plans
Increase in number of shares available under the Plan (in shares)				1,985,000		10,539,000
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)		2,774,000		2,774,000		2,774,000
2013 Plan | Employee stock purchase plan
Stock Option and Compensation Plans
Number of shares available for future purchase (in shares)		838,182		838,182		838,182
2019 Inducement Plan | Stock options
Stock Option and Compensation Plans
Increase in number of shares available under the Plan (in shares)	1,000,000
Number of shares of common stock available for issuance under the Plan (in shares)		897,000		897,000		897,000
Number of initial shares reserved for issuance under the Plan (in shares)							1,000,000

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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 1,873	$ 2,207	$ 4,197	$ 4,677
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	1,093	1,488	2,467	3,110
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	752	709	1,688	1,530
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 28	$ 10	$ 42	$ 37

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, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 1,873	$ 2,207	$ 4,197	$ 4,677
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	951	989	2,104	2,159
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 922	$ 1,218	$ 2,093	$ 2,518

Share-Based Compensation - Su_3

Share-Based Compensation - Summary of Stock Option Activity (Details) - Stock options shares in Thousands	6 Months Ended
	Jun. 30, 2020$ / sharesshares
Number of Shares Underlying Options
Outstanding, beginning balance (in shares) | shares	6,780
Granted (in shares) | shares	696
Exercised (in shares) | shares	(54)
Forfeited (in shares) | shares	(260)
Expired (in shares) | shares	(7)
Outstanding, ending balance (in shares) | shares	7,155
Vested and exercisable, June 30. 2020 (in shares) | shares	3,720
Vested and expected to vest, June 30. 2020 (in shares) | shares	6,845
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 10.89
Granted (in dollars per share) | $ / shares	3.87
Exercised (in dollars per share) | $ / shares	2.65
Forfeited (in dollars per share) | $ / shares	15.59
Expired (in dollars per share) | $ / shares	1.59
Outstanding, ending balance (in dollars per share) | $ / shares	10.11
Vested and exercisable, June 30. 2020 (in dollars per share) | $ / shares	16.19
Vested and expected to vest, June 30. 2020 (in dollars per share) | $ / shares	$ 10.41

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, 2020$ / sharesshares
Restricted Stock Units
Outstanding, beginning balance (in shares) | shares	1,481
Awarded (in shares) | shares	362
Vested (in shares) | shares	(112)
Forfeited (in shares) | shares	(95)
Outstanding, ending balance (in shares) | shares	1,636
Expected to vest (in shares) | shares	1,430
Weighted Average Grant-Date Fair Value
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 7.79
Awarded (in dollars per share) | $ / shares	3.61
Vested (in dollars per share) | $ / shares	18.72
Forfeited (in dollars per share) | $ / shares	5.39
Outstanding, ending balance (in dollars per share) | $ / shares	6.26
Expected to vest (in dollars per share) | $ / shares	$ 4.10

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Tax Credit Carryforward [Line Items]
Income tax benefit	$ 386	$ (4)	$ 3,695	$ (9)
Income tax receivable	1,764		1,764		$ 882
CARES Act
Tax Credit Carryforward [Line Items]
Income tax receivable	$ 1,800		$ 1,800

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Jun. 30, 2020	Dec. 31, 2019
Fair Value Measurements
Transfer of assets from Level 1 to Level 2 of the fair value measurement hierarchy	$ 0
Available for sale securities	0	$ 0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Money market funds
Fair Value Measurements
Investments	242,354,000	108,585,000
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Corporate debt securities
Fair Value Measurements
Investments		0
Recurring basis | Significant other observable inputs (Level 2) | Money market funds
Fair Value Measurements
Investments	0	0
Recurring basis | Significant other observable inputs (Level 2) | Corporate debt securities
Fair Value Measurements
Investments		13,875,000
Recurring basis | Significant unobservable inputs (Level 3) | Money market funds
Fair Value Measurements
Investments	$ 0	0
Recurring basis | Significant unobservable inputs (Level 3) | Corporate debt securities
Fair Value Measurements
Investments		$ 0

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Thousands	Oct. 30, 2018USD ($)shares	May 31, 2019USD ($)licensed_productshares	Dec. 31, 2018USD ($)	Sep. 30, 2011USD ($)
Commitments and contingencies
Number of licensed products | licensed_product		1
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				$ 56,500
License Agreements | Archemix | C5 Licensed Product | First indication | Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone				30,500
License Agreements | Archemix | C5 Licensed Product | Second and third indication | Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone				23,500
License Agreements | Archemix | C5 Licensed Product | Sustained delivery applications | Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone				2,500
License Agreements | Archemix | C5 Licensed Product | Achievement of specified commercial milestones | Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone				$ 22,500
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			$ 23,500
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			$ 70,000
Inception 4
Commitments and contingencies
Contingent consideration arrangements, maximum amount	$ 105,000
Contingent consideration arrangements, maximum amount (in shares) | shares	7,200,000
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	$ 45,000
Inception 4 | Wet AMD Product
Commitments and contingencies
Clinical and marketing approval milestones	$ 60,000
Research and Development Expense | License Agreements | University Of Massachusetts (UMass) | miniCEP290 | Achievement of specified clinical and regulatory milestones
Commitments and contingencies
Payments for license fees		$ 14,750
Shares issued for license fees (in shares) | shares		75,000
Research and Development Expense | License Agreements | University Of Massachusetts (UMass) | miniCEP290 | Specified commercial sales milestones with respect to a licensed product
Commitments and contingencies
Payments for license fees		$ 48,000
Research and Development Expense | 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		15,700
Research and Development Expense | 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		48,000
Research and Development Expense | 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		3,100
Research and Development Expense | 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		$ 9,600