IVERIC bio (ISEE) 10-K 27 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Feb. 24, 2020	Jun. 30, 2019
Document And Entity Information
Entity Registrant Name	IVERIC bio, Inc.
Entity Central Index Key	0001410939
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Shell Company	false
Entity Filer Category	Accelerated Filer
Entity Public Float			$ 51.6
Entity Common Stock, Shares Outstanding (in shares)		49,688,230
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 125,699	$ 131,201
Prepaid expenses and other current assets	2,043	2,086
Income tax receivable	882	0
Total current assets	128,624	133,287
Property and equipment, net	173	335
Right-of-use assets, net	496
Income tax receivable, non-current	882	3,529
Other assets	12	14
Total assets	130,187	137,165
Current liabilities
Accrued research and development expenses	6,860	7,337
Accounts payable and accrued expenses	5,629	5,869
Lease liability, current	495
Total current liabilities	12,984	13,206
Total liabilities	12,984	13,206
Stockholders' equity
Preferred stock—$0.001 par value, 5,000,000 shares authorized, no shares issued or outstanding	0	0
Common stock—$0.001 par value, 200,000,000 shares authorized, 49,627,064 and 41,397,197 shares issued and outstanding at December 31, 2019 and December 31, 2018, respectively	50	41
Additional paid-in capital	597,679	545,585
Accumulated deficit	(480,526)	(421,667)
Total stockholders' equity	117,203	123,959
Total liabilities and stockholders' equity	$ 130,187	$ 137,165

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	49,627,064	41,397,197
Common stock, shares outstanding (in shares)	49,627,064	41,397,197

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Collaboration revenue	$ 0	$ 0	$ 209,977
Operating expenses:
Research and development	39,644	41,737	66,289
General and administrative	21,628	23,612	35,683
Total operating expenses	61,272	65,349	101,972
Income (loss) from operations	(61,272)	(65,349)	108,005
Interest income	2,151	2,389	1,522
Gain on extinguishment of Royalty Purchase Liability	0	125,000	0
Other income (expense)	151	(16)	(34)
Income (loss) before income tax benefit	(58,970)	62,024	109,493
Income tax benefit	(111)	(1,063)	(4,712)
Net income (loss)	$ (58,859)	$ 63,087	$ 114,205
Net income (loss) per common share:
Basic (in dollars per share)	$ (1.39)	$ 1.70	$ 3.18
Dilutive (in dollars per share)	$ (1.39)	$ 1.70	$ 3.17
Weighted average common shares outstanding:
Basic (in shares)	42,224	37,061	35,919
Dilutive (in shares)	42,224	37,088	36,007

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ (58,859)	$ 63,087	$ 114,205
Other comprehensive income
Unrealized gain on available for sale securities, net of tax	0	0	212
Other comprehensive income	0	0	212
Comprehensive income (loss)	$ (58,859)	$ 63,087	$ 114,417

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) shares in Thousands, $ in Thousands	Total	Junior Series A Preferred Stock	Common Stock	Additional paid-in capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)
Balance at beginning of period (in shares) at Dec. 31, 2016		0	35,733
Balance at beginning of period at Dec. 31, 2016	$ (94,618)	$ 0	$ 36	$ 504,517	$ (598,959)	$ (212)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plans and warrants (in shares)			377
Issuance of common stock under employee stock compensation plans and warrants	71		$ 0	71
Share-based compensation	18,171			18,171
Net income	114,205				114,205
Unrealized gain on available for sale securities, net of tax	212					212
Balance at end of period (in shares) at Dec. 31, 2017		0	36,110
Ending balance at Dec. 31, 2017	38,041	$ 0	$ 36	522,759	(484,754)	0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock related to acquisition (in shares)			5,175
Issuance of common stock related to acquisition	11,694		$ 5	11,689
Issuance of common stock under employee stock compensation plans and warrants (in shares)			112
Issuance of common stock under employee stock compensation plans and warrants	65			65
Share-based compensation	11,072			11,072
Net income	63,087				63,087
Unrealized gain on available for sale securities, net of tax	0
Balance at end of period (in shares) at Dec. 31, 2018		0	41,397
Ending balance at Dec. 31, 2018	123,959	$ 0	$ 41	545,585	(421,667)	0
Increase (Decrease) in Stockholders' Equity
Issuance of common stock and pre-funded warrants, net (in shares)			7,750
Issuance of common stock and pre-funded warrants through underwritten offering, net of issuance costs	42,565		$ 8	42,557
Issuance of common stock related to acquisition (in shares)			75
Issuance of common stock related to acquisition	85				85
Issuance of common stock under employee stock compensation plans and warrants (in shares)			405
Issuance of common stock under employee stock compensation plans and warrants	273		$ 1	272
Share-based compensation	9,180			9,180
Net income	(58,859)				(58,859)
Unrealized gain on available for sale securities, net of tax	0
Balance at end of period (in shares) at Dec. 31, 2019		0	49,627
Ending balance at Dec. 31, 2019	$ 117,203	$ 0	$ 50	$ 597,679	$ (480,526)	$ 0

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities
Net income (loss)	$ (58,859)	$ 63,087	$ 114,205
Adjustments to reconcile net loss to net cash (used in) provided by operating activities
Depreciation	162	183	2,763
Amortization of premium and discounts on investment securities	0	0	140
Non-cash charge on acquired in-process research and development	0	5,619	0
Gain on sale of property and equipment	(150)	0	0
Non-cash gain on extinguishment of royalty purchase agreement	0	(125,000)	0
Deferred income taxes	0	0	(3,366)
Share-based compensation	9,180	11,072	18,171
Stock-based consideration in connection with license acquisition	85	0	0
Changes in operating assets and liabilities:
Income tax receivable	1,765	1,387	(1,387)
Due from Novartis Pharma AG	0	0	3,531
Prepaid expense and other assets	45	1,070	370
Accrued interest receivable	0	0	466
Accrued research and development expenses	(477)	2,353	(42,256)
Accounts payable and accrued expenses	(241)	(1,682)	(4,481)
Deferred revenue	0	0	(209,977)
Net cash used in operating activities	(48,490)	(41,911)	(121,821)
Investing Activities
Purchase of marketable securities	0	0	(12,014)
Maturities of marketable securities	0	0	166,806
Proceeds from sale of assets	150		0
Net cash provided by investing activities	150	0	154,792
Financing Activities
Proceeds from employee stock plan purchases and stock option exercises	273	65	71
Net cash provided by financing activities	42,838	6,140	71
Net change in cash and cash equivalents	(5,502)	(35,771)	33,042
Cash and cash equivalents
Beginning of period	131,201	166,972	133,930
End of period	125,699	131,201	166,972
Supplemental disclosure of cash paid
Income taxes received, net	(1,893)	(2,467)	(245)
Supplemental disclosures of non-cash information related to investing activities
Change in unrealized gain (loss) on available for sale securities, net of tax	0	0	212
Common stock issued to acquire net assets of Inception 4, Inc.	0	11,694	0
Operating right-of-use assets obtained in exchange for lease obligations	1,469
Public Stock Offering
Financing Activities
Proceeds from issuance of common stock and pre-funded warrants, net	42,565	0	0
Inception 4
Financing Activities
Proceeds from issuance of common stock and pre-funded warrants, net	$ 0	$ 6,075	$ 0

Business

Business	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business	Business Description of Business and Organization IVERIC bio, Inc. (the “Company” or “IVERIC”) 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 therapeutics for age-related retinal diseases and gene therapy product candidates for orphan inherited retinal diseases ("IRDs"). In April 2019, the Company changed its name from Ophthotech Corporation to IVERIC bio, Inc. as it continued to broaden its focus to include gene therapies. The Company believes that both therapeutics and gene therapy serve important roles in drug development and providing potential treatment options for patients suffering from retinal diseases. Its most advanced therapeutic product candidate is Zimura® (avacincaptad pegol), a complement C5 inhibitor. In October 2019, the Company announced initial, top-line data from a randomized, controlled clinical trial ("OPH2003 trial") of Zimura in geographic atrophy ("GA") secondary to dry age-related macular degeneration ("AMD"). The top-line data confirmed that Zimura met the prespecified primary endpoint in the trial in reducing the rate of GA growth in patients with dry AMD. The reduction in the mean rate of GA growth over 12 months using the square root transformation was 0.110 mm (p-value = 0.0072) for the Zimura 2 mg group as compared to the corresponding sham control group and 0.124 mm (p-value = 0.0051) for the Zimura 4 mg group as compared to the corresponding sham control group, indicating an approximate 27% relative reduction in the mean rate of GA growth over 12 months when compared with sham for both dose groups. These data for both dose groups were statistically significant and the Company believes demonstrate a clinically relevant reduction in rate of GA growth. Based on its review of the safety data to date, Zimura was generally well tolerated over 12 months of administration in this clinical trial. Over this 12-month period, there were no investigator-reported ocular serious adverse events, no Zimura-related adverse events, no cases of Zimura-related intraocular inflammation, no cases of Zimura-related increased intraocular pressure, no cases of endophthalmitis, and no discontinuations attributed by investigators to Zimura. OPH2003 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. The Company believes that the safety and efficacy results from the OPH2003 trial could potentially satisfy the U.S. Food and Drug Administration's ("FDA's") requirements as one of the two pivotal clinical trials typically required for marketing approval of a pharmaceutical product. The Company is preparing for an international, randomized, double masked, sham controlled, multi-center Phase 3 clinical trial of Zimura in this indication ("ISEE2008 trial") with the goal of beginning patient enrollment during the first quarter of 2020. The Company currently has two gene therapy product candidates in preclinical development and several collaborative gene therapy sponsored research programs ongoing. Subject to successful completion of preclinical development and manufacturing under current good manufacturing practices, and regulatory review, the Company plans to initiate a Phase 1/2 clinical trial for IC-100, its lead gene therapy product candidate, during the fourth quarter of 2020. The Company's therapeutics portfolio consists of Zimura and its preclinical development program of High temperature requirement A serine peptidase 1 protein ("HtrA1") inhibitors. The Company is targeting the following diseases with Zimura: • GA, which is the advanced stage of 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. The Company previously also evaluated Zimura in combination with Lucentis® (ranibizumab), an anti-vascular endothelial growth factor ("anti-VEGF") agent, for the treatment of wet AMD, for which the Company completed a Phase 2a clinical trial during the fourth quarter of 2018. The Company is developing its HtrA1 inhibitor program for GA and potentially other age-related retinal diseases. The Company's gene therapy portfolio consists of several ongoing research and preclinical development programs that use adeno-associated virus ("AAV") for gene delivery. These AAV gene therapy programs are targeting the following orphan IRDs: • rhodopsin-mediated autosomal dominant retinitis pigmentosa ("RHO-adRP") which is characterized by progressive and severe bilateral loss of vision leading to blindness; • IRDs associated with mutations in the BEST1 gene, including Best vitelliform macular dystrophy ("Best disease"), which is generally characterized by bilateral egg yolk-like lesions in the macula that, over time, progress to atrophy and loss of vision; • Leber Congenital Amaurosis type 10 ("LCA10"), which is characterized by severe bilateral loss of vision at or soon after birth; • autosomal recessive Stargardt disease; and • IRDs associated with mutations in the USH2A gene, which include Usher syndrome type 2A and USH2A -associated nonsyndromatic autosomal recessive retinitis pigmentosa.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation and Consolidation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") and include all adjustments necessary for the fair presentation of the Company's financial position for the periods presented. The consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. Segment and geographic information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating and reporting segment. Use of Estimates The preparation of financial statements and related disclosures in conformity with GAAP requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. The amounts of assets and liabilities reported in the Company's Consolidated Balance Sheets and the amount of expenses reported for each of the periods presented are affected by estimates and assumptions, which are used for, but not limited to, accounting for research and development costs, revenue recognition, accounting for share-based compensation and accounting for income taxes. Actual results could differ from those estimates. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of 90 days or less when purchased to be cash equivalents. The carrying amounts reported in the Balance Sheets for cash and cash equivalents are valued at cost, which approximates their fair value. As of December 31, 2019 , the Company had cash and cash equivalents of approximately $125.7 million . The Company believes that its cash and cash equivalents as of December 31, 2019 will be sufficient to fund its operations and capital expenditure requirements as currently planned for at least the next 12 months from the filing of the Company's Annual Report on Form 10-K. 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 balance 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 currently relies exclusively upon a single third-party manufacturer to provide the drug substance for Zimura on a purchase order basis. The Company also engages a single third-party manufacturer to provide fill/finish services for clinical supplies of Zimura. In addition, the Company currently relies upon a single third-party supplier to supply on a purchase order basis the proprietary polyethylene glycol reagent 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, its RHO-adRP gene therapy product candidate, and IC-200, its BEST1 -related IRDs gene therapy product candidate, 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 GMP manufacture of the lead compound for its HtrA1 inhibitors program 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 or insolvency, the Company believes that there are a limited number of potential replacement manufacturers, and the Company likely would incur added costs and delays in identifying or qualifying such replacements. Foreign Currency Translation The Company considers the U.S. dollar to be its functional currency. Expenses denominated in foreign currencies are translated at the exchange rate on the date the expense is incurred. The effect of exchange rate fluctuations on translating foreign currency assets and liabilities into U.S. dollars is included in the Consolidated Statements of Operations and Comprehensive Loss. Foreign exchange transaction gains and losses are included in the results of operations and are not material in the Company's financial statements. Financial Instruments Cash equivalents 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. 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 space and has entered into various other agreements in conducting its business. At inception, the Company determines whether an agreement represents a lease and at commencement evaluates each lease agreement to determine whether the lease is an operating or financing lease. Some of the Company's lease agreements have contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses, although its remaining outstanding lease for its principal offices has no further options, allowances, holidays or clauses. As described below under "Recently Adopted Accounting Pronouncements," the Company adopted the Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) as of January 1, 2019. Pursuant to ASU 2016-02, all of the Company's leases outstanding on January 1, 2019 continued to be classified as operating leases. With the adoption of ASU 2016-02, the Company recorded an operating lease right-of-use asset and an operating lease liability on its Consolidated Balance Sheet. Right-of-use lease assets represent the Company's right to use the underlying asset for the lease term and the lease obligation represents the Company's commitment to make the lease payments arising from the lease. Right-of-use lease assets and obligations are recognized at the commencement date based on the present value of remaining lease payments over the lease term. As the Company’s leases do not provide an implicit discount rate, the Company has used an estimated incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The right-of-use lease asset includes any lease payments made prior to commencement and excludes any lease incentives. The lease term may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Operating lease expense is recognized on a straight-line basis over the lease term, subject to any changes in the lease or expectations regarding the terms. Variable lease costs such as common area costs and property taxes are expensed as incurred. For all office lease agreements the Company combines lease and nonlease components. Leases with an initial term of 12 months or less are not recorded on the Company's Consolidated Balance Sheet. Prior to the adoption of ASU 2016-02, when the Company's lease agreements contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses, the Company recorded a deferred rent asset or liability equal to the difference between the rent expense and the future minimum lease payments due. The lease expense related to operating leases was recognized on a straight-line basis in the Company's Consolidated Statements of Operations over the term of each lease. In cases where the lessor granted the Company leasehold improvement allowances that reduced the Company's lease expense, the Company capitalized the improvements as incurred and recognized deferred rent, which was amortized over the shorter of the lease term or the expected useful life of the improvements. Property and Equipment Property and equipment, which consists mainly of clinical equipment, computers, software, other office equipment, and leasehold improvements, are carried at cost less accumulated depreciation. Depreciation is computed over the estimated useful lives of the respective assets, generally three to ten years, using the straight-line method. Amortization of leasehold improvements is recorded over the shorter of the lease term or estimated useful life of the related asset. Research and Development The Company's research and development expenses primarily consist of costs associated with the manufacturing, development, and preclinical and clinical testing of the Company's 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 ("CMOs") 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. Prior to January 1, 2019, share-based compensation awarded to non-employees was subject to revaluation over the vesting term of each award. Subsequent to the adoption of ASU 2018-07, Improvements to Non-Employee Share-Based Payment Accounting, the value of non-employee share-based compensation is measured on the date of grant, similar to share-based compensation granted to employees. Stock Options The Company estimates the fair value of stock options granted to employees, non-employees and non-employee directors 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 years ended December 31, 2019 , 2018 and 2017 : Years ended December 31, 2019 2018 2017 Expected common stock price volatility 110% 85% 81% Risk-free interest rate 1.38-2.54 2.39% - 2.95% 1.82% - 2.38% Expected term of options (years) 4.8 6.0 6.1 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. Share-based compensation expense includes expenses related to stock options and RSUs granted to employees, non-employee directors and consultants, as well as the option granted to employees to purchase shares under the ESPP, all of which have been reported in the Company’s Statements of Operations as follows: Years ended December 31, 2019 2018 2017 Research and development $ 4,260 $ 4,967 $ 11,114 General and administrative 4,920 6,105 7,057 Total $ 9,180 $ 11,072 $ 18,171 Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842). Under the new guidance, lessees will be required to recognize the following for all leases (with the exception of short-term leases) at the commencement date: (1) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (2) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. Under the new guidance, lessor accounting is largely unchanged. Certain targeted improvements were made to align, where necessary, lessor accounting with the lessee accounting model and Topic 606, Revenue from Contracts with Customers. The new lease guidance simplified the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off-balance sheet financing. Publicly-traded business entities were required to apply the amendments in ASU 2016-2 for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years (i.e., January 1, 2019, for a calendar year entity). Early application was permitted for all publicly-traded business entities and all nonpublicly-traded business entities upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach does not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. On January 1, 2019 the Company adopted this guidance utilizing the simplified transition option that allows companies to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company elected to adopt the package of practical expedients permitted in Accounting Standards Codification Topic 842, or ASC 842. Accordingly, the Company continues to account for its existing operating leases as operating leases under the new guidance, without reassessing whether the contracts contain a lease under ASC 842 or whether classification of the operating leases would be different under ASC Topic 842. As a result of the adoption, the Company recognized, as of the beginning of the period of adoption, right-of-use assets and lease liabilities of approximately $1.5 million , which represents the present value of its remaining lease payments using a weighted average estimated incremental borrowing rate of 6% , on its Consolidated Balance Sheet. The adoption of this standard did not have a material impact on the Company’s results of operations for the year ended December 31, 2019. In June 2018, the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting , which supersedes ASC 505-50 and expands the scope of ASC 718 to include all share-based payments arrangements related to the acquisition of goods and services from both employees and nonemployees. For public companies, the amendments became effective for annual reporting periods beginning after December 15, 2018, including interim periods within those annual periods. During the three months ended March 31, 2019, the Company adopted this guidance. The adoption did not have a material impact on its financial statements for the year ended and as of December 31, 2019. Recent Accounting Pronouncements In June 2016, the FASB issued 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. Early adoption is permitted. The Company does not expect the adoption of this new accounting guidance to have a material impact on its financial statements or disclosures. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) , which modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, including, among other changes, the consideration of costs and benefits when evaluating disclosure requirements. For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted. The Company does not expect the adoption of this new accounting guidance to have a material impact on its financial statements or disclosures. In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This guidance is effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years, with early adoption permitted. The Company does not expect the adoption of this new accounting guidance to have a material impact on its financial statements or disclosures. In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808) , which clarifies the interaction between the guidance for collaborative arrangements (Topic 808) and the new revenue recognition standard (Topic 606). For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted. The Company does not expect the adoption of this new accounting guidance to have a material impact on its financial statements or disclosures.

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Common Stock	Common Stock Public Offering On December 6, 2019, the Company completed an underwritten public offering in which it sold 6,250,000 shares of its common stock at a public offering price of $ 4.00 per share, and it sold to certain investors pre-funded warrants to purchase 3,750,000 shares of its common stock at a public offering price of $ 3.999 per share underlying each warrant. The offering included an option for the underwriters to purchase up to an additional 1,500,000 shares of its common stock, which was subsequently exercised in full by the underwriters. The shares of its common stock were sold to the underwriters at a purchase price of $3.736 per share and the pre-funded warrants were sold to the underwriters at a purchase price of $ 3.735 per share underlying each warrant. The pre-funded warrants are immediately exercisable with certain restrictions and do not expire. The net proceeds from the offering, after deducting underwriting discounts and commissions of $ 3.0 million and other offering expenses of $ 0.4 million, was approximately $ 42.6 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 governing the pre-funded warrants in the applicable agreement, the Company determined that the pre-funded warrants meet the criteria required to be classified as an equity award subject to the guidance in ASC 815-10 and 815-40 and should effectively be treated as outstanding common shares in both basic and diluted EPS calculations. miniCEP290 Program - University of Massachusetts On July 22, 2019, the Company entered into its exclusive license agreement with the University of Massachusetts ("UMass") for rights to its miniCEP290 program (the "miniCEP290 License Agreement"). Pursuant to the terms of the miniCEP290 License Agreement, the Company issued to UMass 75,000 shares of the Company's common stock, which were valued at approximately $ 0.1 million. Based on and relying on certain representations made by UMass, the Company issued those shares pursuant to an exemption from registration afforded by Section 4(a)(2) of the Securities Act of 1933, as amended (the "Securities Act").

Net Income (Loss) Per Common Sh

Net Income (Loss) Per Common Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Net Income (Loss) Per Common Share	Net Income (Loss) Per Common Share Basic and diluted net income (loss) per common share is determined by dividing net income (loss) by the weighted average common shares and pre-funded warrants outstanding during the period. 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 income (loss) per common share for the periods indicated: Years ended December 31, 2019 2018 2017 Basic and diluted net income (loss) per common share calculation: Net income (loss) $ (58,859 ) $ 63,087 $ 114,205 Weighted average common shares outstanding - basic 42,224 37,061 35,919 Plus: net effect of dilutive stock options and unvested restricted stock units — 27 88 Weighted average common shares outstanding - dilutive 42,224 37,088 36,007 Net income (loss) per common share - basic $ (1.39 ) $ 1.70 $ 3.18 Net income (loss) per common share - diluted $ (1.39 ) $ 1.70 $ 3.17 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: Years ended December 31, 2019 2018 2017 Stock options outstanding 6,780 5,873 5,179 Restricted stock units 1,481 601 182 Total 8,261 6,474 5,361

Cash and Cash Equivalents

Cash and Cash Equivalents	12 Months Ended
	Dec. 31, 2019
Cash and Cash Equivalents [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 December 31, 2019 and December 31, 2018 the Company had cash and cash equivalents of approximately $125.7 million and $131.2 million , respectively. Cash and cash equivalents at December 31, 2019 and December 31, 2018 included cash of $3.2 million and $4.4 million , respectively. As of December 31, 2019 and December 31, 2018 , cash and cash equivalents also included $122.5 million and $126.8 million , respectively, of investments in money market funds and certain short-term 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 December 31, 2019 or at December 31, 2018, respectively. The Company believes that its existing cash and cash equivalents as of December 31, 2019 will be sufficient to fund its operations and capital expenditure req uiremen ts as currently planned for at least the next 12 months from the filing of the Company's Annual Report on Form 10-K. This estimate is based on the Company's current business plan, including the continuation of its current research and development programs including the ISEE2008 trial. This estimate does not reflect any additional expenditures, including associated development costs, in the event it in-licenses or acquires any new product candidates or if it commences any new sponsored research programs. 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.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements ASC 820, Fair Value Measurements and Disclosures , defines fair value as the price that would be received to sell an asset, or paid to transfer a liability, in the principal or most advantageous market in an orderly transaction between market participants on the measurement date. The fair value standard also establishes a three-level hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. The Company reviews investments on a periodic basis for other than temporary impairments. This review is subjective as it requires management to evaluate whether an event or change in circumstances has occurred in the period that may have a significant adverse effect on the fair value of the investment. The Company uses the market approach to measure fair value for its financial assets. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets. The Company classifies its investment-grade corporate debt securities within the fair value hierarchy as Level 2 assets, as it primarily utilizes quoted market prices or rates for similar instruments to value these securities. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability on the measurement date. The three levels are defined as follows: • Level 1—inputs to the valuation methodology are quoted prices (unadjusted) for an identical asset or liability in an active market. The Company's Level 1 assets consist of investments in money market funds and U.S. Treasury securities. • Level 2—inputs to the valuation methodology include quoted prices for a similar asset or liability in an active market or model-derived valuations in which all significant inputs are observable for substantially the full term of the asset or liability. The Company's Level 2 assets may consist of investments in investment-grade corporate debt securities. • Level 3—inputs to the valuation methodology are unobservable and significant to the fair value measurement of the asset or liability. The Company does not hold any assets that are measured using Level 3 inputs. The 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 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 active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets Investments in money market funds* $ 108,585 $ — $ — Investments in corporate debt securities* $ — $ 13,875 $ — The following table presents, for each of the fair value hierarchy levels required under ASC 820, the Company's assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2018 : Fair Value Measurement Using Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets Investments in money market funds* $ 97,402 $ — $ — Investments in corporate debt securities* — 29,425 — * Investments in money market funds and corporate debt securities with maturities less than 90 days are reflected in cash and cash equivalents in the accompanying Balance Sheets. No transfer of assets between Level 1 and Level 2 of the fair value measurement hierarchy occurred during the years ended December 31, 2019 or December 31, 2018 .

Inception 4 Acquisition

Inception 4 Acquisition	12 Months Ended
	Dec. 31, 2019
Asset Acquisition [Abstract]
Inception 4 Acquisition	Inception 4 Acquisition In October 2018, the Company entered into an Agreement and Plan of Merger (the “Inception 4 Merger Agreement”) by and among the Company, Orion Ophthalmology Merger Sub, Inc., a Delaware corporation and a direct, wholly owned subsidiary of the Company (“Merger Sub I”), Orion Ophthalmology LLC, a Delaware limited liability company and a direct, wholly owned subsidiary of the Company (“Orion”), Inception 4, Inc., a Delaware corporation ("Inception 4"), and, solely in its capacity as the representative, agent and attorney-in-fact of the equityholders of Inception 4, Fortis Advisors LLC, a Delaware limited liability company. Pursuant to the Inception 4 Merger Agreement, in October 2018, the Company acquired Inception 4 through the merger of Merger Sub I with and into Inception 4, with Inception 4 surviving as a direct, wholly owned subsidiary of the Company, and as part of the same overall transaction, the merger of Inception 4 with and into Orion, with Orion surviving as a direct, wholly owned subsidiary of the Company (the transactions are collectively referred to as the "Inception 4 Merger"). Prior to the Inception 4 Merger, Inception 4 was a privately held biotechnology company focused on the research and development of small molecule HtrA1 inhibitors for age-related retinal diseases in humans. Pursuant to the terms of the Inception 4 Merger Agreement, as upfront consideration, the Company issued approximately 5.2 million shares of the Company’s common stock to the former equityholders of Inception 4, which were valued at approximately $11.7 million based on the closing price of the Company’s common stock on the acquisition date equal to $2.26 per share. Additionally, subject to the terms and conditions of the Inception 4 Merger Agreement, the former equityholders of Inception 4 will be entitled to receive contingent payments up to an aggregate of $105.0 million from the Company for the achievement of specified clinical and regulatory milestones, with $45 million of such potential payments relating to GA and $60 million of such potential payments relating to wet AMD. 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 Inception 4 Merger, 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 Merger, and will be payable in cash thereafter. At closing, the Company acquired all of Inception 4's assets, which included intellectual property and in-process research and development (“IPR&D”) associated with Inception 4’s HtrA1 inhibitor program and approximately $6.1 million in cash. There were no other tangible assets, leases or liabilities. The Company evaluated the acquisition of Inception 4 under ASU No. 2017-01, Business Combinations: Clarifying the Definition of a Business . Based on the results of the analysis performed, the Company concluded that substantially all of the fair value of the gross assets acquired under the Inception 4 Merger Agreement is concentrated in a single identifiable asset. As a result, the Company concluded that the acquisition of Inception 4 does not represent an acquisition of a business and does not qualify as a business combination to be accounted for under ASC 805. Further, the Company concluded that the legal entity is not a variable interest entity under ASC 810 - Consolidation . Consequently, the Company concluded that the acquisition of Inception 4 should be accounted for as an asset acquisition under ASC 805-50. As the contingent consideration is not a derivative under ASC 815 - Derivatives and Hedging , any contingent payments will be recognized when earned or achieved and such amounts will be expensed upon payment for pre-commercial activities and capitalized for regulatory approvals and post-commercial activities. Further, as the acquired IPR&D has no alternative future use, in accordance with ASC 730, at closing, the Company charged to expense its allocated fair value of $6.9 million , which is the total acquisition consideration including transaction costs of $1.3 million less the cash acquired.

Licensing and Commercialization

Licensing and Commercialization Agreement	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Licensing and Commercialization Agreement	Licensing and Commercialization Agreements Zimura License Agreement with Archemix Corp. In September 2011, the Company entered into an amended and restated exclusive license agreement with Archemix Corp. ("Archemix") relating to anti-C5 aptamers (as amended, the "C5 License Agreement"). The C5 License Agreement superseded a July 2007 agreement between the Company and Archemix. Under the C5 License Agreement, the Company holds exclusive worldwide licenses, subject to certain pre–existing rights, under specified patents and technology owned or controlled by Archemix to develop, make, use, sell, offer for sale, distribute for sale, import and export pharmaceutical products comprised of or derived from an anti-C5 aptamer for the prevention, treatment, cure or control of human indications, diseases, disorders or conditions of the eye, adnexa of the eye, orbit and optic nerve, other than certain expressly excluded applications. In connection with the C5 License Agreement, the Company paid Archemix an upfront licensing fee of $1.0 million and issued to Archemix an aggregate of 2,000,000 shares of its series A-1 preferred stock and 500,000 shares of its series B-1 preferred stock. The Company has paid Archemix an aggregate of $2.0 million in fees based on its achievement of specified clinical milestone events under the C5 License Agreement. This amount does not include a milestone payment obligation of $1.0 million triggered by the positive, initial top-line data from the OPH2003 trial, which is included in the Company's Balance Sheet as of December 31, 2019 and its Statement of Operations for the year ended December 31, 2019. Under the C5 License Agreement, for each anti-C5 aptamer product that the Company may develop under the agreement, including Zimura, it is obligated to make additional payments to Archemix of up to an aggregate of $56.5 million if it 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, it is also obligated to make additional payments to Archemix of up to an aggregate of $22.5 million if it achieves specified commercial milestones based on net product sales of all anti-C5 products licensed under the agreement. It is also obligated to pay Archemix a double-digit percentage of specified non-royalty payments it 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. Unless earlier terminated, the C5 License Agreement will expire upon the latest of 12 years after the first commercial sale in any country of the last licensed product, the expiration of the last-to-expire valid claim of the licensed patents that covers a licensed product, and the date on which no further payments of sublicensing income are to be received by the Company. Either the Company or Archemix may terminate the C5 License Agreement if the other party materially breaches the agreement and the breach remains uncured for a specified period. Archemix may also terminate the C5 License Agreement, or may convert the Company's exclusive license under the agreement to a non-exclusive license, if the Company challenges or assists a third party in challenging the validity or enforceability of any of the patents licensed under the agreement. The Company may terminate the agreement at any time and for any or no reason effective at the end of a specified period following its written notice of termination to Archemix. IC-100 Agreements with the University of Florida Research Foundation and the University of Pennsylvania In June 2018, the Company entered into an exclusive global license agreement (the "RHO-adRP License Agreement") with the University of Florida Research Foundation, Incorporated ("UFRF") and the University of Pennsylvania ("Penn" and collectively with UFRF, the "Licensors"). Under the agreement, the Licensors granted the Company a worldwide, exclusive license under specified patent rights and a worldwide, non-exclusive license under specified know-how, including specified preclinical data, to manufacture, develop and commercialize certain AAV gene therapy products for the treatment of rhodopsin-mediated diseases. The rights granted under the RHO-adRP License Agreement included certain patent rights covering IC-100, the Company's novel AAV gene therapy product candidate intended to treat RHO-adRP. In June 2018, the Company paid UFRF, on behalf of both Licensors, a $0.5 million upfront license issuance fee in connection with entry into the agreement, which was recorded as a research and development expense, as well as accrued patent prosecution expenses of approximately $30 thousand , which was recorded as a general and administrative expense. Under the agreement, the Company agreed to pay an annual license maintenance fee in the low double-digit thousands of dollars, which will be payable on an annual basis until the first commercial sale of a licensed product. In addition, the Company agreed to reimburse UFRF for the costs and expenses of patent prosecution and maintenance related to the licensed patent rights. The Company further agreed to pay UFRF, on behalf of both Licensors, 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 additionally, up to an aggregate of $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, on behalf of both Licensors, royalties at a low single-digit percentage of net sales of licensed products. Such royalties are subject to customary reductions for lack of patent coverage and loss of regulatory exclusivity. In addition, such royalties with respect to any licensed product in any country may be offset by a specified portion of any royalty payments actually paid by the Company in such country under third-party licenses for patent rights or other intellectual property rights that are necessary to manufacture, develop and commercialize the licensed product in such country. The Company's obligation to pay royalties under the RHO-adRP License Agreement will continue on a licensed product-by-licensed product and country-by-country basis until the latest of: • the expiration of the last-to-expire licensed patent rights covering a licensed product in the country of sale; • the expiration of regulatory exclusivity covering a licensed product in the country of sale; and • ten years from the first commercial sale of the applicable licensed product in the country of sale. Beginning on the earlier of (i) the calendar year following the first commercial sale of a licensed product and (ii) the first business day of 2031, the Company is also obligated to pay certain minimum royalties, not to exceed an amount in the low hundreds of thousands of dollars on an annual basis, which minimum royalties are creditable against the Company's royalty obligation with respect to net sales of licensed products due for the year in which the minimum royalty is paid. In addition, if the Company or an affiliate sublicenses any of the licensed patent rights to a third party, the Company will be obligated to pay UFRF, on behalf of both Licensors, a low double-digit percentage of the consideration received in exchange for such sublicense. 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, on behalf of both Licensors, aggregate payments in the low double-digit millions of dollars based on certain marketing approval and commercial sales milestones with respect to such other product candidate. If the Company sells such priority review voucher to a third party, it will be obligated to pay UFRF, on behalf of both licensors, a low double-digit percentage of any consideration received from such third party in connection with such sale. Unless earlier terminated by the Company, the RHO-adRP License Agreement will expire upon the expiration of the Company’s obligation to pay royalties to UFRF on net sales of licensed products. The Company may terminate the agreement at any time for any reason upon prior written notice to UFRF. Penn or UFRF may terminate the RHO-adRP License Agreement in the event of certain breaches by the Company or in the event of certain insolvency events regarding the Company. In addition to the exclusive license agreement, the Company and Penn also entered into to a Master-Sponsored Research Agreement (the "RHO-adRP MSRA"), facilitated by the Penn Center for Innovation. Under the RHO-adRP MSRA, the Company and Penn are conducting preclinical studies of IC-100, as well as a natural history study of RHO-adRP patients. The total amount of funding for the sponsored research covered by statements of work under the RHO-adRP MSRA that the Company has committed to date and is expecting to commit to is in the low single-digit millions of dollars. IC-200 Agreements with University of Pennsylvania and University of Florida Research Foundation In April 2019, the Company entered into an exclusive global license agreement (the "BEST1 License Agreement") with Penn and UFRF. The Company entered into the BEST1 License Agreement by exercising its exclusive option rights under an option agreement that it previously entered into with Penn and UFRF in October 2018. Under the BEST1 License Agreement, Penn and UFRF granted the Company a worldwide, exclusive license under specified patent rights and specified know-how and a worldwide, non-exclusive license under other specified know-how to research, develop, manufacture and commercialize certain AAV gene therapy products, including IC-200, for the treatment of Best disease and other BEST1- related IRDs. In May 2019, the Company paid Penn, for the benefit of the Licensors, a $0.2 million upfront license issuance fee, which was recorded as a research and development expense, and the Company paid UFRF accrued patent prosecution expenses of approximately $18 thousand , which was recorded as a general and administrative expense. The Company has also agreed to pay Penn, for the benefit of the Licensors, an annual license maintenance fee in the low double-digit thousands of dollars, which will be payable on an annual basis until the first commercial sale of a licensed product. In addition, the Company have agreed to pay Penn, for the benefit of the Licensors, a one-time patent grant fee in the low triple-digit thousands of dollars, upon the issuance of a U.S. patent that claims inventions disclosed in the licensed patent rights or know-how or inventions generated under certain related sponsored research agreements with Penn or UFRF, and that is exclusively licensed to the Company. Furthermore, it has agreed to reimburse Penn and UFRF for the costs and expenses of patent prosecution and maintenance related to the licensed patent rights. The Company has further agreed to pay Penn, for the benefit of the Licensors, up to an aggregate of $15.7 million if it 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 it achieves these same milestones with respect to a different licensed product. In addition, it has agreed to pay Penn, for the benefit of the Licensors, up to an aggregate of $48.0 million if it achieves specified commercial sales milestones with respect to one licensed product, and up to an aggregate of an additional $9.6 million if it 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, royalties at a low single-digit percentage of net sales of licensed products. Such royalties are subject to customary deductions, credits, and reductions for lack of patent coverage and loss of regulatory exclusivity. In addition, such royalties with respect to any licensed product in any country may be offset by a specified portion of any royalty payments actually paid by the Company in such country under third-party licenses to patent rights or other intellectual property rights that are necessary to research, develop, manufacture and commercialize the licensed product in such country. Its obligation to pay royalties under the BEST1 License Agreement will continue on a licensed product-by-licensed product and country-by-country basis until the latest of: • the expiration of the last-to-expire licensed patent rights covering the sale of the applicable licensed product in the country of sale; • the expiration of regulatory exclusivity covering the applicable licensed product in the country of sale; and • 10 years from the first commercial sale of the applicable licensed product in the country of sale. Beginning on the earlier of the calendar year following the first commercial sale of a licensed product and calendar year 2032, the Company is also obligated to pay certain minimum royalties, not to exceed an amount in the mid tens of thousands of dollars on an annual basis, which minimum royalties are creditable against its royalty obligation with respect to net sales of licensed products due in the year the minimum royalty is paid. If the Company or any of its affiliates sublicense any of the licensed patent rights to a third party, it will be obligated to pay Penn, for the benefit of the Licensors, a high single-digit to a mid ten's percentage of the consideration received in exchange for such sublicense, with the applicable percentage based upon the stage of development of the sublicensed product at the time it or the applicable affiliate enters into the sublicense. 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 BEST1 License Agreement, it 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 it sells such a priority review voucher to a third party, it 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. The BEST1 License Agreement, unless earlier terminated by the Company or Penn or UFRF, will expire upon the expiration of the Company's obligation to pay royalties on net sales of licensed products. Before the effectiveness of an IND for a licensed product, the Company may terminate the BEST1 License Agreement with respect to such licensed product or in its entirety, at any time for any reason upon prior written notice to Penn and UFRF. Following the effectiveness of an IND for a licensed product, it may terminate the BEST1 License Agreement with respect to such licensed product by providing Penn prior written notice and a certification that it is ceasing all use, research and development and commercialization of such licensed product, subject to certain limited exceptions. It may also terminate the BEST1 License Agreement if Penn or UFRF materially breaches the BEST1 License Agreement and does not cure such breach within a specified cure period. Penn or UFRF may terminate the BEST1 License Agreement if the Company materially breaches the BEST1 License Agreement and does not cure such breach within a specified cure period, if it experiences a specified insolvency event, if it ceases to carry on the entirety of its business related to the licensed patent rights, if it ceases for more than four consecutive quarters to make any payment of earned royalties on net sales of licensed products following the commencement of commercialization thereof, unless such cessation is based on safety concerns that the Company is actively attempting to address, or if it, any of its affiliates or any of its sublicensees challenges or assists a third party in challenging the validity, scope, patentability, and/or enforceability of the licensed patent rights. If it materially breaches certain diligence obligations under the BEST1 License Agreement with respect to only one licensed product, then Penn and UFRF may only terminate its rights and licenses under the BEST1 License Agreement for such licensed product, but not for other licensed products. In addition to the exclusive license agreement, the Company and Penn also entered into a Master-Sponsored Research Agreement (the "BEST1 MSRA"), facilitated by the Penn Center for Innovation. Under the BEST1 MSRA, the Company and Penn are conducting preclinical studies of IC-200, as well as natural history studies of patients with BEST1 -related IRDs. The Company expects to enter into additional statements of work under the BEST1 MSRA for additional preclinical studies. The total amount of funding for the sponsored research covered by statements of work under the BEST1 MSRA that the Company has committed to date and expects to commit to is in the low single-digit millions of dollars. License Agreement with University of Massachusetts for the miniCEP290 Program In July 2019, the Company entered into the miniCEP290 License Agreement with UMass by exercising its exclusive option rights under an option agreement and a sponsored research agreement that it previously entered into with UMass in February 2018. Under the miniCEP290 License Agreement, UMass granted it a worldwide, exclusive license under specified patent rights and specified biological materials and a non-exclusive license under specified know-how to make, have made, use, offer to sell, sell, have sold and import products for the treatment of diseases associated with mutations in the CEP290 gene, including LCA10. In July 2019, the Company issued to UMass 75,000 shares of its common stock following execution of the miniCEP290 License Agreement pursuant to an exemption from registration afforded by Section 4(a)(2) of the Securities Act. In September 2019, it paid UMass a $0.4 million upfront license fee, which was recorded as a research and development expense, and it paid UMass accrued patent prosecution expenses of approximately $18 thousand , which was recorded as a general and administrative expense. The Company has also agreed to pay UMass an annual license maintenance fee in the low double-digit thousands of dollars, which will be payable on an annual basis until the expiration of the royalty term for the licensed products. Furthermore, it has agreed to reimburse UMass for the costs and expenses of patent prosecution and maintenance related to the licensed patent rights. The Company has further agreed to pay UMass up to an aggregate of $14.75 million in cash and issue up to 75,000 shares of its common stock if it achieves specified clinical and regulatory milestones with respect to a licensed product. In addition, the Company has agreed to pay UMass up to an aggregate of $48.0 million if it 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. Its obligation to pay royalties under the miniCEP290 License Agreement will continue on a licensed product-by-licensed product and country-by-country basis until the later of: (a) the expiration of the last-to-expire licensed patent rights covering the sale of the applicable licensed product in the country of sale, or (b) 10 years from the first commercial sale of the applicable licensed product in the country of sale. Beginning with the calendar year following receipt of marketing approval for a licensed product, it is also obligated to pay certain minimum royalties, not to exceed an amount in the mid-double-digit thousands of dollars on an annual basis, which minimum royalties are creditable against its royalty obligation with respect to net sales of licensed products due in the year the minimum royalty is paid. If the Company or any of its affiliates sublicenses any of the licensed patent rights or know-how to a third party, it 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 it or the applicable affiliate enters into the sublicense. 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 it subsequently uses such priority review voucher in connection with a different product candidate outside the scope of the miniCEP290 License Agreement, it will be obligated to pay UMass a low-tens percentage of the fair market value of the priority review voucher at the time of approval of such product candidate and a low-twenties percentage of the fair market value of the priority review voucher at the time of achievement of a specified commercial sales milestone for such other product candidate. In addition, if it sells such a priority review voucher to a third party, it will be obligated to pay UMass a low-thirties percentage of any consideration received from such third party in connection with such sale. The miniCEP290 License Agreement, unless earlier terminated by the Company or UMass, will expire upon the expiration of its obligation to pay royalties to UMass on net sales of licensed products. The Company may terminate the miniCEP290 License Agreement at any time for any reason upon prior written notice to UMass. It may also terminate the miniCEP290 License Agreement if UMass materially breaches the miniCEP290 License Agreement and does not cure such breach within a specified cure period. UMass may terminate the miniCEP290 License Agreement if the Company materially breaches the miniCEP290 License Agreement and does not cure such breach within a specified cure period. Prior Licensing and Commercialization Agreement with Novartis Pharma AG Prior to 2018, the Company's revenues resulted from payments received under the Novartis Agreement, as modified by the July 2017 Letter Agreement. These two agreements are described below. The Company used the relative selling price method to allocate arrangement consideration to the Company’s performance obligations under the Novartis Agreement. The Company completed the deliverables under the Novartis Agreement and the July 2017 Letter Agreement during the third quarter of 2017. In May 2014, the Company entered into the Novartis Agreement. Under the Novartis Agreement, the Company granted Novartis exclusive rights under specified patent rights, know-how and trademarks controlled by the Company to manufacture standalone Fovista products and products combining Fovista with an anti-VEGF agent to which Novartis has rights in a co-formulated product, for the treatment, prevention, cure or control of any human disease, disorder or condition of the eye, and to develop and commercialize those licensed products in all countries outside of the United States (the “Novartis Territory”). The Company agreed to use commercially reasonable efforts to complete its ongoing pivotal Phase 3 clinical program for Fovista and Novartis agreed to use commercially reasonable efforts to develop a standalone Fovista product and a co-formulated product containing Fovista and an anti-VEGF agent to which Novartis has rights, and to use commercially reasonable efforts, subject to obtaining marketing approval, to commercialize licensed products in the Novartis Territory in accordance with agreed development and marketing plans. In July 2017, the Company and Novartis entered into the July 2017 Letter Agreement to streamline the process and timeline for evaluating data from the OPH1004 trial once it became available. In October 2017, following the failure of the Phase 3 Fovista program and pursuant to the terms of the July 2017 Letter Agreement, Novartis elected to terminate the Novartis Agreement with immediate effect. In May 2014, Novartis paid the Company a $200.0 million upfront payment. In each of September 2014 and March 2015, the Company achieved, and Novartis paid the Company, a $50.0 million enrollment-based milestone, and in June 2016, the Company achieved, and Novartis paid the Company, a $30.0 million enrollment-based milestone, for an aggregate total of $130.0 million in enrollment-based milestones under the Novartis Agreement. The Company used the relative selling price method to allocate these payments to contract deliverables based on its performance obligations under the Novartis Agreement. Activities under the Novartis Agreement were evaluated under ASC 605-25, Revenue Recognition—Multiple Element Arrangements (“ASC 605-25”) (as amended by ASU 2009-13, Revenue Recognition (“ASU 2009-13”)) to determine if they represented a multiple element revenue arrangement. The Novartis Agreement included the following deliverables: (1) an exclusive license to commercialize Fovista outside the United States (the “License Deliverable”); (2) the performance obligation to conduct research and development activities related to the Phase 3 Fovista clinical trials and certain Phase 2 trials for Fovista (the “R&D Activity Deliverable”); (3) the performance obligation to supply API to Novartis for development and manufacturing purposes (the “Manufacturing Deliverable”) and (4) the Company’s obligation to participate on the joint operating committee established under the terms of the Novartis Agreement and related subcommittees (the “Joint Operating Committee Deliverable”). The Company’s obligation to provide access to clinical and regulatory information as part of the License Deliverable included the obligation to provide access to all clinical data, regulatory filings, safety data and manufacturing data to Novartis which was necessary for the commercialization of Fovista in the Novartis Territory. The R&D Activity Deliverable included the right and responsibility for the Company to conduct the Phase 3 Fovista clinical program and other Phase 2 studies of Fovista which were necessary or desirable for regulatory approval or commercialization of Fovista. The Manufacturing Deliverable included the obligation for the Company to supply API to Novartis for clinical purposes, for which Novartis agreed to pay the Company’s manufacturing costs. The Joint Operating Committee Deliverable included the obligation to participate in the Joint Operating Committee and related subcommittees at least through the first anniversary of regulatory approval in the European Union. All of these deliverables were deemed to have stand-alone value and to meet the criteria to be accounted for as separate units of accounting under ASC 605-25. Factors considered in this determination included, among other things, the subject of the licenses and the research and development and commercial capabilities of Novartis. Accordingly, each unit was accounted for separately. The Novartis Agreement included a termination right for the Company in the event that specified governmental actions prevented the parties from materially progressing the development or commercialization of licensed products. If the Company elected to exercise this termination option, it would have been required to pay a substantial termination fee equivalent to the entire upfront payment amount. The Company concluded that this termination provision constituted a contingent event that was unknown at the inception of the agreement. As such, the Company recorded the $200.0 million upfront payment in deferred revenue, long-term until such time that the contingency related to this termination provision was resolved. In July 2017, the contingency was resolved when the Company permanently waived this termination right as part of the July 2017 Letter Agreement. The July 2017 Letter Agreement also provided Novartis with a shorter notice period in the event Novartis determined to terminate the Novartis Agreement in certain circumstances. In addition, the July 2017 Letter Agreement provided Novartis with a fully paid-up, royalty free license to use data from the Lucentis monotherapy arms of the Company's Phase 2b OPH1001 trial and Phase 3 OPH1002 and OPH1003 trials in the Novartis Territory in connection with the development, manufacturing and commercialization of Novartis-controlled anti-VEGF products. The Lucentis study data license continues until July 3, 2022. The Company evaluated the July 2017 Letter Agreement under ASC 605-25 and determined that the July 2017 Letter Agreement does not create any new deliverables. The Company is treating the Fovista license granted at the inception of the Novartis Agreement and the Lucentis study data license granted under the July 2017 Letter Agreement as one collective technology license (the "Licenses") delivered at the inception of the Novartis Agreement. In addition, as the waiver of its right to terminate the Novartis Agreement as a result of specified governmental actions resolved the Company’s contingency with respect to such termination right and the associated termination fee, the Company allocated the entire previously deferred amount, $200.0 million , to the deliverables that were determined based on the relative selling price at contract inception. Upon entry into the July 2017 Letter Agreement in July 2017, the Company immediately recognized as revenue $189.8 million of the upfront payment allocated to contract deliverables completed during prior periods. Upon termination of the OPH1004 trial in August 2017, the Company recognized the remaining $16.9 million of collaboration revenue, attributable to the R&D Deliverable, previously deferred under the Novartis Agreement. In total, during the third quarter of 2017, the Company recognized $206.7 million in previously deferred collaboration revenue in connection with the Novartis Agreement. The recognition of this revenue did not impact the Company's cash balance. Below is a summary of the components of the Company's collaboration revenue for the years ended December 31, 2019 , 2018 , and 2017 : Years ended December 31, 2019 2018 2017 License revenue $ — $ — $ 152,912 Research and development activity revenue — — 56,180 API transfer revenue — — 754 Joint operating committee revenue — — 131 Total collaboration revenue $ — $ — $ 209,977

Financing Agreement with Novo H

Financing Agreement with Novo Holdings A/S	12 Months Ended
	Dec. 31, 2019
Related Party Transactions [Abstract]
Financing Agreement with Novo Holdings A/S	Financing Agreement with Novo Holdings A/S In May 2013, the Company entered into a Purchase and Sale Agreement (the "Novo Agreement") with Novo Holdings A/S ("Novo" and formerly Novo A/S), pursuant to which the Company obtained financing in three tranches in an aggregate amount equal to $125.0 million in return for the sale to Novo of aggregate royalties of a mid-single digit percentage on worldwide sales of (a) Fovista, (b) certain Fovista-related Products ("Fovista-Related Products"), and (c) certain other antagonists of platelet-derived growth factor ("PDGF"), if any, that the Company initiated development activities for prior to the fifth anniversary of the Novo Agreement (collectively, the "Anti-PDGF Royalty Products"). The Company received the cash payments from Novo in each of May 2013, January 2014 and November 2014. the Company received cash payments of $41.7 million , or $125.0 million in the aggregate. The $125.0 million in aggregate proceeds from the three financing tranches under the Novo Agreement represented the full funding available under the Novo Agreement, and prior to December 31, 2018, was recorded as a royalty purchase liability on the Company's Balance Sheet, in accordance with ASC 730, Research and Development . Because there was a significant related party relationship between the Company and Novo, the Company treated its obligation to make royalty payments under the Novo Agreement as an implicit obligation to repay the funds advanced by Novo. On December 31, 2018, the Company and Novo entered into a letter agreement (the "Novo Termination Agreement"), that terminated the Novo Agreement. As a result of the Novo Termination Agreement, Novo relinquished all rights to receive royalties based on net sales of Anti-PDGF Royalty Products. In exchange, the Company agreed to forbear from any future filing, prosecution, maintenance or enforcement of any intellectual property rights related to Anti-PDGF Royalty Products, and from granting any third party any right or license in any such intellectual property rights or clinical study data generated by or on behalf of the Company, its affiliates, licensees or sublicensees, for the development, manufacture or commercialization of Anti-PDGF Royalty Products or any other antagonists of PDGF. The foregoing restriction does not apply to gene therapies (so long as the Company does not grant any rights or licenses to intellectual property or clinical study data related to Fovista or Fovista-Related Products). The Company further agreed, until December 31, 2028, not to develop, manufacture, seek or obtain regulatory approval for, or commercialize any Anti-PDGF Royalty Products without the prior written consent of Novo. The foregoing restriction does not apply to any gene therapies (so long as the Company does not utilize data related to Fovista or Fovista-Related Products). As a result of the Novo Termination Agreement, the Company has no obligation to repay Novo the $125.0 million through future product royalties or any other development activities. Accordingly, the Company extinguished the $125.0 million royalty purchase liability from its Consolidated Balance Sheet at December 31, 2018 and recognized a related gain of $125.0 million in its Consolidated Statements of Operations for the year ended December 31, 2018. The extinguishment of the royalty purchase liability and the related gain did not impact the Company's cash balance during that period, as the Company had received the proceeds related to the royalty purchase liability in prior periods.

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment	Property and Equipment Property and equipment as of December 31, 2019 and 2018 were as follows: Useful Life (Years) December 31, December 31, Manufacturing and clinical equipment 7 - 10 $ 47 $ 412 Computer, software and other office equipment 5 933 933 980 1,345 Accumulated depreciation (807 ) (1,010 ) Property and equipment, net $ 173 $ 335 For the years ended December 31, 2019 , 2018 and 2017 , depreciation expense was $0.2 million , $0.2 million and $2.8 million , respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company utilizes the liability method of accounting for deferred 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. Deferred income taxes reflect the net effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. A reconciliation of the statutory U.S. federal rate to the Company's effective tax rate is as follows: Years ended December 31, 2019 2018 2017 Percent of pre-tax income: U.S. federal statutory income tax rate 21.0 % 21.0 % 35.0 % State taxes, net of federal benefit 10.9 % 18.5 % 14.6 % Permanent items (1.0 )% 4.0 % 4.0 % Remeasurement of deferred tax assets — % — % 49.9 % Impact of state rate changes 0.1 % (0.2 )% (27.9 )% Research and development credit 2.8 % (2.4 )% — % Alternative minimum tax credit — % — % (1.3 )% Change in valuation allowance (33.6 )% (42.6 )% (78.6 )% Effective income tax rate 0.2 % (1.7 )% (4.3 )% The components of income tax benefit are as follows: Years ended December 31, 2019 2018 2017 Current: Federal $ — $ — $ 173 State (111 ) (1,063 ) (1,356 ) Deferred: Federal — — (3,529 ) State — — — Income tax benefit $ (111 ) $ (1,063 ) $ (4,712 ) Significant components of the Company's deferred tax assets (liabilities) for 2019 and 2018 consist of the following: As of December 31, 2019 2018 Deferred tax assets (liabilities) License and technology payments 7,116 7,221 Share-based compensation 22,131 20,342 Accrued expenses 362 371 Right-of-use asset (163 ) — Lease obligation 162 — Depreciation (18 ) (28 ) Federal and state net operating loss carryforwards 105,375 88,766 Research and development credits 7,353 5,933 Other 6 5 Deferred income tax assets 142,324 122,610 Valuation allowance (142,324 ) (122,610 ) Net deferred tax assets $ — $ — The Company considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of taxable income during the periods in which the temporary differences representing net future deductible amounts become deductible. The Company incurred tax losses in 2019 and 2018. The Company has carried forward its federal and state tax losses due to the inability of carryback claims. Federal NOLs incurred prior to 2018 will begin to expire in 2034 if not utilized. Post 2017 Federal NOLs have an unlimited life. The state NOLs are expected to begin to expire in 2028. Due to the Company's history of losses and lack of other positive evidence to support taxable income, the Company has recorded a valuation allowance against those remaining deferred tax assets that are not expected to be realized. As of December 31, 2019, the Company has federal NOL carryforwards of approximately $369.7 million . For the year ended December 31, 2019 and 2018, the Company recorded a benefit from income taxes of $0.1 million and $1.1 million , respectively, due primarily to the settlements of a local tax audits. For the year ended December 31, 2017, the Company recorded a benefit from income taxes of $4.7 million which was related to a $3.5 million reduction in its valuation allowances for AMT credits to reflect the impact of the TCJA enactment and the settlement of a state franchise tax audit for $1.4 million , partially offset by the reversal of previously recorded benefits related to the change in unrealized gains of the Company's investment portfolio. During 2019, the Company received $1.8 million related to the refund of the afore-mentioned AMT credits and recorded a tax receivable of $1.8 million to reflect the refund of AMT credits it expects to receive over the next three years. The Company generated net income before income taxes for the years ended December 31, 2018 and 2017. This income was due to the Novo Termination Agreement and the July 2017 Letter Agreement with Novartis which had previously been recorded on the company's federal and state income tax returns. This recognition of income resulted in the reduction of a deferred tax asset that was completely offset by a previously recorded valuation allowance. With respect to the remaining deferred tax assets, except for the AMT credits previously discussed above, there was no change in the amount of assets realizable at December 31, 2019. In the second quarter of 2017, the IRS concluded an audit of the Company’s U.S. federal income tax returns for the years 2013, 2014 and 2015, resulting in an immaterial amount of additional tax due. Federal NOLs for 2016 and general business credits generated between 2007 and 2016 remain subject to audit. Pursuant to ASC 740, Income Taxes , the Company routinely evaluates the likelihood of success if challenged on income tax positions claimed on its income tax returns. During the year ended December 31, 2019 , the Company reduced certain deferred tax assets by $19.7 million and increased the corresponding valuation allowance by an equivalent amount. Additionally, the Company amended certain state income tax returns to claim a refund for taxes previously paid. These claims may result in refunds to the Company of up to approximately $4.8 million . These items have not been recognized in the financial statements and if disallowed by the tax authorities, would not result in an adjustment to the Company’s effective tax rate, its balance sheet or its cash flow statements for the current year. The Company's position with respect to uncertain tax positions is set forth below: Opening balance $ 13,983 Gross amount of increases in unrecognized tax benefits during the period - current year provisions — Gross amount of increases in unrecognized tax benefits during the period - prior year provisions 18 Gross amount of decreases in unrecognized tax benefits during the period - other (1,579 ) Decreases due to settlement with tax authorities during the period (195 ) Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period — Closing Balance $ 12,227 As the Company is currently under audit by the New Jersey Division of Taxation, an estimate of unrecognized tax benefits that may be realized over the next twelve months is expected to be in the range of zero to approximately $4.8 million . The Company will continue to evaluate its ability to realize its deferred tax assets on a periodic 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 product candidates 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.

Operating Leases

Operating Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Operating Leases	Operating Leases The Company leases office space located in New York, New York and Princeton, New Jersey under non-cancelable operating lease arrangements. The lease for the Company's New York office expires at the end of June 2020, and the sublease for the Company's Princeton office expires in March 2020. As of January 1, 2019, the Company recognized right-of-use assets and lease liabilities of approximately $1.5 million , which represents the present value of its remaining lease payments using a weighted average estimated incremental borrowing rate of 6% . For the years ended December 31, 2019 , 2018 and 2017 , lease and rent expense was $1.0 million , $0.8 million and $3.6 million , respectively. Cash paid from operating cash flows for amounts included in the measurement of lease liabilities was $1.0 million year ended December 31, 2019 . At December 31, 2019 , the Company's operating leases had a weighted average remaining lease term of 0.5 years. The following presents the maturity of the Company's operating lease liabilities as of December 31, 2019 : December 31, 2019 2020 $ 504 Total remaining obligation $ 504 Less imputed interest $ (9 ) Present value of lease liabilities $ 495 During December 2019, the Company entered into a lease for office space located in Cranbury, New Jersey. The Company has recognized a right-of-use asset and lease liability of approximately $0.2 million when the lease commenced in February 2020. The term of the lease for the Company's Cranbury office expires at the end of February 2023.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Zimura - Archemix Corp. The Company is party to an agreement with Archemix Corp., or Archemix, under which the Company in-licensed rights in certain patents, patent applications and other intellectual property related to Zimura and pursuant to which the Company may be required to pay sublicense fees and make milestone payments (the "C5 License Agreement"). In October 2019, following its announcement of positive, initial top-line data from the OPH2003 trial, the Company became obligated under the C5 License Agreement to pay Archemix a clinical milestone of $1.0 million , which is recorded as a payable in the Company's Consolidated Balance Sheet as of December 31, 2019 and as an expense in the Consolidated Statement of Operations for the year ended December 31, 2019. In addition, for each anti-C5 aptamer product that the Company may develop under the agreement, including Zimura, the Company is obligated to make additional 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 licensed products. 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 Research Foundation and the University of Pennsylvania Under its exclusive license agreement with UFRF and Penn for rights to IC-100, the Company is obligated to make payments to UFRF, for the benefit of 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 Research Foundation 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-ten's 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 the miniCEP290 License Agreement, 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. HtrA1 Inhibitors - Former Equityholders of Inception 4 Under 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 Inception 4 Merger, 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 Merger, 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. IVERIC bio, Inc., 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. IVERIC bio, Inc., 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. This case is currently in the discovery phase. On February 7, 2018, a shareholder derivative action was filed against the members of the Company’s Board of Directors in the New York Supreme Court Commercial Division, captioned Cano v. Guyer, et al., No. 650601/2018. The complaint alleges that the defendants breached their fiduciary duties to the Company by adopting a compensation plan that overcompensates the non-employee members of the Board relative to boards of companies of comparable market capitalization and size. The complaint also alleges that the defendants were unjustly enriched as a result of the alleged conduct. The complaint purports to seek unspecified damages, on behalf of the Company, attorneys’ fees, and other costs, as well as an order directing the Company to reform and improve its corporate governance and internal procedures to comply with applicable laws. The Company filed a motion to dismiss this case on May 14, 2018. On June 4, 2018, the plaintiff filed an amended complaint. On June 25, 2018, the Company filed a renewed motion to dismiss this case. On December 3, 2018, the parties filed a stipulation of settlement that contemplates that the Company will adopt certain compensation-related governance reforms and does not obligate the defendants or the Company to pay any monetary damages. The court approved the settlement at a hearing on March 12, 2019. As part of the settlement, in April 2019 the Company paid $0.3 million in fees and costs to plaintiff's counsel. As contemplated by the settlement, the Company's board of directors adopted certain compensation-related governance reforms, including a non-employee director compensation policy, which its stockholders approved on May 15, 2019 at its 2019 annual meeting. On August 31, 2018, a shareholder derivative action was filed against current and former members of the Company's Board of Directors and certain current and former officers of the Company in the United States District Court for the Southern District of New York, captioned Luis Pacheco v. David R. Guyer, et al., Case No. 1:18-cv-07999. The complaint, which is based substantially on the facts alleged in the CAC, alleges that the defendants breached their fiduciary duties to the Company and wasted the Company's corporate assets by failing to oversee the Company's business, and also alleges that the defendants were unjustly enriched as a result of the alleged conduct, including through receipt of bonuses, stock options and similar compensation from the Company, and through sales of the Company's stock between March 2, 2015 and December 12, 2016. The complaint purports to seek unspecified damages on the Company's behalf, attorneys’ fees, and other costs, as well as an order directing the Company to reform and improve its corporate governance and internal procedures to comply with applicable laws, including submitting certain proposed amendments to the Company's corporate charter, bylaws and corporate governance policies for vote by the Company's stockholders. On December 14, 2018, the Company filed a motion to dismiss the complaint. On September 19, 2019, the court denied its 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. 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 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.

Stock-Based Compensation and Co

Stock-Based Compensation and Compensation Plans	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Stock-Based Compensation and Compensation Plans	Stock-Based Compensation and Compensation Plans The Company adopted its 2007 Stock Incentive Plan (the "2007 Plan") for employees, non-employee directors and consultants for the purpose of advancing the interests of the Company's stockholders by enhancing its ability to attract, retain and motivate persons who are expected to make important contributions to the Company. The 2007 Plan provided for the granting of stock option awards, RSUs, and other stock-based and cash-based awards. Following the effectiveness of the 2013 Stock Incentive Plan described below in connection with the closing of the Company's initial public offering, the Company is no longer granting additional awards under the 2007 Plan. In August 2013, the Company's board of directors adopted, and the Company's stockholders approved, the 2013 Stock Incentive Plan (the "2013 Plan"), which became effective immediately prior to the closing of the Company's initial public offering. In June 2015, the Company’s board of directors adopted a first amendment to the 2013 Plan. The 2013 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, RSUs, restricted stock awards and other stock-based awards. Upon the effectiveness of the 2013 Plan, the number of shares of the Company's common stock that were reserved for issuance under the 2013 Plan was the sum of (1) a number of shares (up to a maximum of approximately 3,359,641 shares) that is equal to the sum of 739,317 shares (the number of shares of the Company's common stock then available for issuance under the 2007 Plan), and such number of shares of the Company's common stock that are subject to outstanding awards under the 2007 Plan that expire, terminate or are otherwise surrendered, canceled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right, plus (2) an annual increase, to be added the first business day of each fiscal year, beginning with the fiscal year ending December 31, 2014 and continuing until, and including, the fiscal year ending December 31, 2023, equal to the lowest of 2,542,372 shares of the Company's common stock, 4% of the number of shares of the Company's common stock outstanding on the first day of the fiscal year and an amount determined by its board of directors. The Company's employees, officers, directors, consultants and advisors are eligible to receive awards under the 2013 Plan. However, incentive stock options may only be granted to employees of the Company. Annual increases under the evergreen provisions of the 2013 Plan 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 4% of the total number of shares of the Company's common stock outstanding as of January 1, 2020. As of December 31, 2019 , the Company had approximately 732,000 shares available for grant under the 2013 Plan. In October 2019, the Company's board of directors adopted the 2019 Inducement Stock Incentive Plan (the “2019 Inducement Plan”) to reserve 1,000,000 shares of its common stock to be used exclusively for grants of awards to individuals that were not previously employees or directors of the Company as a material inducement to such individuals’ entry into employment with the Company within the meaning of 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. As of December 31, 2019 , the Company had approximately 650,000 shares available for grant under the 2019 Inducement Plan. In April 2016, the board of directors adopted the ESPP pursuant to which the Company may sell up to an aggregate of 1,000,000 shares of common stock. The ESPP was approved by the Company’s stockholders in June 2016. The ESPP allows eligible employees to purchase common stock at a price per share equal to 85% of the lower of the fair market value of the common stock at the beginning or end of each six month offering period during the term of the ESPP. The first offering period began in September 2016. A summary of the stock option activity, weighted average exercise prices, options outstanding and exercisable as of December 31, 2019 , 2018 and 2017 is as follows (in thousands except weighted average exercise price): Years ended December 31, 2019 2018 2017 Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Outstanding, December 31, 2018 5,903 $ 13.72 5,284 $ 19.58 3,359 $ 39.92 Granted 1,610 $ 4.26 1,293 $ 1.67 3,024 $ 3.50 Exercised (80 ) $ 2.66 — $ — (20 ) $ 1.64 Expired or forfeited (653 ) $ 21.16 (674 ) $ 36.54 (1,079 ) $ 38.17 Outstanding, December 31, 2019 6,780 $ 10.89 5,903 $ 13.72 5,284 $ 19.58 Years ended December 31, 2019 2018 2017 Options exercisable at December 31, 2019 3,317 2,709 1,954 Weighted average grant date fair value (per share) of options granted during the period $ 3.37 $ 1.20 $ 2.45 As of December 31, 2019 , there were approximately 6,468,000 options outstanding, net of estimated forfeitures, that had vested or are expected to vest. The weighted-average exercise price of these options was $11.24 per option; the weighted-average remaining contractual life of these options was 7.7 years; and the aggregate intrinsic value of these options was approximately $10.6 million . A summary of the stock options outstanding and exercisable as of December 31, 2019 is as follows (in thousands except exercise prices and weighted average exercise price): December 31, 2019 Options Outstanding Options Exercisable Range of Exercise Prices Total Options Outstanding Weighted Average Remaining Life (Years) Weighted Average Exercise Price Number Exercisable Weighted Average Exercise Price $1.13-$2.79 1,350 8.8 $ 1.59 433 $ 1.76 $2.80-$2.96 1,725 7.9 $ 2.93 876 $ 2.93 $2.97-$4.87 1,444 8.1 $ 4.18 648 $ 4.48 $4.88-$31.09 1,090 8.7 $ 7.13 216 $ 14.89 $31.10-$73.22 1,171 5.1 $ 45.14 1,144 $ 45.01 6,780 7.8 $ 10.89 3,317 $ 18.38 Aggregate Intrinsic Value $ 28,475 $ 10,557 Cash proceeds from, and the aggregate intrinsic value of, stock options exercised during the years ended December 31, 2019 , 2018 and 2017 , respectively, were as follows: Years ended December 31, 2019 2018 2017 Cash proceeds from options exercised $ 192 $ — $ 33 Aggregate intrinsic value of options exercised $ 135 $ — $ 43 In connection with stock option awards granted to employees, the Company recognized approximately $5.9 million , $7.6 million and $13.1 million in share-based compensation expense during the years ended December 31, 2019 , 2018 and 2017 , respectively, net of expected forfeitures. As of December 31, 2019 , there were approximately $8.0 million of unrecognized compensation costs, net of estimated forfeitures, related to stock option awards granted to employees, which are expected to be recognized over a remaining weighted average period of 3.1 years. In connection with stock option awards granted to consultants, the Company recognized approximately $0.3 million , $0.2 million and $0.3 million in share-based compensation expense during the years ended December 31, 2019 , 2018 and 2017 , respectively, net of expected forfeitures. As of December 31, 2019 , there were approximately $0.2 million of unrecognized compensation costs, net of estimated forfeitures, related to stock option awards granted to consultants, which are expected to be recognized over a remaining weighted average period of 3.6 years. The following table presents a summary of the Company's outstanding RSU awards granted as of December 31, 2019 (in thousands except weighted average grant-date fair value): Restricted Stock Units Weighted Average Grant-Date Fair Value Outstanding, December 31, 2018 679 $ 15.61 Awarded 1,090 $ 4.57 Vested (255 ) $ 13.94 Forfeited (33 ) $ 16.35 Outstanding, December 31, 2019 1,481 $ 7.79 As of December 31, 2019 , there were approximately 1,287,000 RSUs outstanding, net of estimated forfeitures, that are expected to vest. The weighted-average fair value of these RSUs was $5.39 per share; and the aggregate intrinsic value of these RSUs was approximately $11.0 million . In connection with RSUs granted to employees, the Company recognized approximately $3.0 million , $3.3 million and $4.4 million in share-based compensation expense during the years ended December 31, 2019 , 2018 and 2017 , respectively, net of expected forfeitures. As of December 31, 2019 , there was approximately $5.0 million of unrecognized compensation costs, net of estimated forfeitures, related to RSUs granted to employees, which are expected to be recognized over a remaining weighted average period of 2.7 years. The total fair value of the RSUs that vested during the year ended December 31, 2019 was $3.6 million . In connection with RSUs granted to consultants, the Company recognized a de minimis amount in share-based compensation expense during the year ended December 31, 2019 , net of expected forfeitures. In connection with RSUs granted to consultants, the Company recognized approximately $ 0.1 million in share-based compensation expense during the year ended December 31, 2018 . As of December 31, 2019 , there were approximately $0.1 million of unrecognized compensation costs, net of estimated forfeitures, related to RSUs granted to consultants, which are expected to be recognized over a remaining weighted average period of 3.4 years. In connection with the ESPP made available to employees, the Company recognized approximately $0.1 million and a de minimis amount of share-based compensation expense during the years ended December 31, 2019 and December 31, 2018 , respectively, net of expected forfeitures. As of December 31, 2019 , there was a de minimis amount of unrecognized compensation costs, net of estimated forfeitures, related to the ESPP, which are expected to be recognized over 0.3 years. There were 70,466 shares of common stock issued under the ESPP during the year ended December 31, 2019 . Cash proceeds from ESPP purchases were approximately $81 thousand during the year ended December 31, 2019 . There were 31,413 shares of common stock issued under the ESPP during the year ended December 31, 2018 . As of December 31, 2019 , 881,763 shares were available for future purchases under the ESPP.

Employee Benefit Plan

Employee Benefit Plan	12 Months Ended
	Dec. 31, 2019
Retirement Benefits [Abstract]
Employee Benefit Plan	Employee Benefit Plan The Company maintains a defined contribution 401(k) plan available to employees. Employee contributions are voluntary and are determined on an individual basis, limited by the maximum amounts allowable under federal tax regulations. The Company's matching contributions to employees totaled approximately $0.2 million , $0.2 million and $0.7 million during the years ended December 31, 2019 , 2018 and 2017 , respectively.

Selected Quarterly Financial In

Selected Quarterly Financial Information (unaudited)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Information (unaudited)	Selected Quarterly Financial Information (unaudited) The following is a summary of the quarterly results of operations for the years ended December 31, 2019 and 2018 : 2019 March 31 June 30 September 30 December 31 Research and development expenses 7,685 10,009 10,383 11,567 General and administrative expenses 5,481 5,198 4,674 6,275 Loss from operations (13,166 ) (15,207 ) (15,057 ) (17,842 ) Net income (loss) attributable to common stockholders $ (12,501 ) $ (14,443 ) $ (14,437 ) $ (17,478 ) Basic earnings (loss) per common share $ (0.30 ) $ (0.35 ) $ (0.35 ) $ (0.39 ) Diluted earnings (loss) per common share $ (0.30 ) $ (0.35 ) $ (0.35 ) $ (0.39 ) 2018 March 31 June 30 September 30 December 31 Research and development expenses 7,686 8,516 9,407 16,128 General and administrative expenses 5,645 6,332 5,968 5,667 Income (loss) from operations (13,331 ) (14,848 ) (15,375 ) (21,795 ) Net income (loss) attributable to common stockholders $ (13,073 ) $ (13,209 ) $ (14,745 ) $ 104,114 Basic earnings (loss) per common share $ (0.36 ) $ (0.37 ) $ (0.41 ) $ 2.62 Diluted earnings (loss) per common share $ (0.36 ) $ (0.37 ) $ (0.41 ) $ 2.62

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation and Consolidation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America ("GAAP") and include all adjustments necessary for the fair presentation of the Company's financial position for the periods presented.
Basis of Consolidation	The consolidated financial statements include the accounts of the Company and its subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.
Segment and geographic information	Segment and geographic information Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating and reporting segment.
Use of Estimates	Use of Estimates The preparation of financial statements and related disclosures in conformity with GAAP requires management to make estimates and judgments that affect the amounts reported in the financial statements and accompanying notes. The Company bases its estimates and judgments on historical experience and on various other assumptions that it believes are reasonable under the circumstances. The amounts of assets and liabilities reported in the Company's Consolidated Balance Sheets and the amount of expenses reported for each of the periods presented are affected by estimates and assumptions, which are used for, but not limited to, accounting for research and development costs, revenue recognition, accounting for share-based compensation and accounting for income taxes. Actual results could differ from those estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of 90 days or less when purchased to be cash equivalents. The carrying amounts reported in the Balance Sheets for cash and cash equivalents are valued at cost, which approximates their fair value.
Concentration of Credit Risk	Concentration of Credit Risk The Company's financial instruments that are exposed to concentration of credit risk consist primarily of cash and cash equivalents. The Company maintains its cash in bank accounts, the balance 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 currently relies exclusively upon a single third-party manufacturer to provide the drug substance for Zimura on a purchase order basis. The Company also engages a single third-party manufacturer to provide fill/finish services for clinical supplies of Zimura. In addition, the Company currently relies upon a single third-party supplier to supply on a purchase order basis the proprietary polyethylene glycol reagent 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, its RHO-adRP gene therapy product candidate, and IC-200, its BEST1 -related IRDs gene therapy product candidate, 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 GMP manufacture of the lead compound for its HtrA1 inhibitors program 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 or insolvency, the Company believes that there are a limited number of potential replacement manufacturers, and the Company likely would incur added costs and delays in identifying or qualifying such replacements.
Foreign Currency Translation	Foreign Currency Translation The Company considers the U.S. dollar to be its functional currency. Expenses denominated in foreign currencies are translated at the exchange rate on the date the expense is incurred. The effect of exchange rate fluctuations on translating foreign currency assets and liabilities into U.S. dollars is included in the Consolidated Statements of Operations and Comprehensive Loss. Foreign exchange transaction gains and losses are included in the results of operations and are not material in the Company's financial statements.
Financial Instruments	Financial Instruments Cash equivalents 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. 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 space and has entered into various other agreements in conducting its business. At inception, the Company determines whether an agreement represents a lease and at commencement evaluates each lease agreement to determine whether the lease is an operating or financing lease. Some of the Company's lease agreements have contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses, although its remaining outstanding lease for its principal offices has no further options, allowances, holidays or clauses. As described below under "Recently Adopted Accounting Pronouncements," the Company adopted the Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) 2016-02, Leases (Topic 842) as of January 1, 2019. Pursuant to ASU 2016-02, all of the Company's leases outstanding on January 1, 2019 continued to be classified as operating leases. With the adoption of ASU 2016-02, the Company recorded an operating lease right-of-use asset and an operating lease liability on its Consolidated Balance Sheet. Right-of-use lease assets represent the Company's right to use the underlying asset for the lease term and the lease obligation represents the Company's commitment to make the lease payments arising from the lease. Right-of-use lease assets and obligations are recognized at the commencement date based on the present value of remaining lease payments over the lease term. As the Company’s leases do not provide an implicit discount rate, the Company has used an estimated incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. The right-of-use lease asset includes any lease payments made prior to commencement and excludes any lease incentives. The lease term may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise that option. Operating lease expense is recognized on a straight-line basis over the lease term, subject to any changes in the lease or expectations regarding the terms. Variable lease costs such as common area costs and property taxes are expensed as incurred. For all office lease agreements the Company combines lease and nonlease components. Leases with an initial term of 12 months or less are not recorded on the Company's Consolidated Balance Sheet. Prior to the adoption of ASU 2016-02, when the Company's lease agreements contained renewal options, tenant improvement allowances, rent holidays and rent escalation clauses, the Company recorded a deferred rent asset or liability equal to the difference between the rent expense and the future minimum lease payments due. The lease expense related to operating leases was recognized on a straight-line basis in the Company's Consolidated Statements of Operations over the term of each lease. In cases where the lessor granted the Company leasehold improvement allowances that reduced the Company's lease expense, the Company capitalized the improvements as incurred and recognized deferred rent, which was amortized over the shorter of the lease term or the expected useful life of the improvements.
Property and Equipment	Property and Equipment Property and equipment, which consists mainly of clinical equipment, computers, software, other office equipment, and leasehold improvements, are carried at cost less accumulated depreciation. Depreciation is computed over the estimated useful lives of the respective assets, generally three to ten years, using the straight-line method. Amortization of leasehold improvements is recorded over the shorter of the lease term or estimated useful life of the related asset.
Research and 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 the Company's 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 ("CMOs") 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. Prior to January 1, 2019, share-based compensation awarded to non-employees was subject to revaluation over the vesting term of each award. Subsequent to the adoption of ASU 2018-07, Improvements to Non-Employee Share-Based Payment Accounting, the value of non-employee share-based compensation is measured on the date of grant, similar to share-based compensation granted to employees. Stock Options The Company estimates the fair value of stock options granted to employees, non-employees and non-employee directors 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 years ended December 31, 2019 , 2018 and 2017 : Years ended December 31, 2019 2018 2017 Expected common stock price volatility 110% 85% 81% Risk-free interest rate 1.38-2.54 2.39% - 2.95% 1.82% - 2.38% Expected term of options (years) 4.8 6.0 6.1 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. Share-based compensation expense includes expenses related to stock options and RSUs granted to employees, non-employee directors and consultants, as well as the option granted to employees to purchase shares under the ESPP, all of which have been reported in the Company’s Statements of Operations as follows: Years ended December 31, 2019 2018 2017 Research and development $ 4,260 $ 4,967 $ 11,114 General and administrative 4,920 6,105 7,057 Total $ 9,180 $ 11,072 $ 18,171
Recently Adopted and Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements In February 2016, the FASB issued ASU No. 2016-2, Leases (Topic 842). Under the new guidance, lessees will be required to recognize the following for all leases (with the exception of short-term leases) at the commencement date: (1) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (2) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. Under the new guidance, lessor accounting is largely unchanged. Certain targeted improvements were made to align, where necessary, lessor accounting with the lessee accounting model and Topic 606, Revenue from Contracts with Customers. The new lease guidance simplified the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off-balance sheet financing. Publicly-traded business entities were required to apply the amendments in ASU 2016-2 for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years (i.e., January 1, 2019, for a calendar year entity). Early application was permitted for all publicly-traded business entities and all nonpublicly-traded business entities upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach does not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. On January 1, 2019 the Company adopted this guidance utilizing the simplified transition option that allows companies to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company elected to adopt the package of practical expedients permitted in Accounting Standards Codification Topic 842, or ASC 842. Accordingly, the Company continues to account for its existing operating leases as operating leases under the new guidance, without reassessing whether the contracts contain a lease under ASC 842 or whether classification of the operating leases would be different under ASC Topic 842. As a result of the adoption, the Company recognized, as of the beginning of the period of adoption, right-of-use assets and lease liabilities of approximately $1.5 million , which represents the present value of its remaining lease payments using a weighted average estimated incremental borrowing rate of 6% , on its Consolidated Balance Sheet. The adoption of this standard did not have a material impact on the Company’s results of operations for the year ended December 31, 2019. In June 2018, the FASB issued ASU No. 2018-07, Improvements to Nonemployee Share-Based Payment Accounting , which supersedes ASC 505-50 and expands the scope of ASC 718 to include all share-based payments arrangements related to the acquisition of goods and services from both employees and nonemployees. For public companies, the amendments became effective for annual reporting periods beginning after December 15, 2018, including interim periods within those annual periods. During the three months ended March 31, 2019, the Company adopted this guidance. The adoption did not have a material impact on its financial statements for the year ended and as of December 31, 2019. Recent Accounting Pronouncements In June 2016, the FASB issued 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. Early adoption is permitted. The Company does not expect the adoption of this new accounting guidance to have a material impact on its financial statements or disclosures. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) , which modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, including, among other changes, the consideration of costs and benefits when evaluating disclosure requirements. For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted. The Company does not expect the adoption of this new accounting guidance to have a material impact on its financial statements or disclosures. In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This guidance is effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years, with early adoption permitted. The Company does not expect the adoption of this new accounting guidance to have a material impact on its financial statements or disclosures. In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808) , which clarifies the interaction between the guidance for collaborative arrangements (Topic 808) and the new revenue recognition standard (Topic 606). For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted. The Company does not expect the adoption of this new accounting guidance to have a material impact on its financial statements or disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Schedule of weighted-average assumptions used to estimate grant date fair value of stock options	The weighted-average assumptions used to estimate grant date fair value of stock options using the Black-Scholes option pricing model were as follows for the years ended December 31, 2019 , 2018 and 2017 : Years ended December 31, 2019 2018 2017 Expected common stock price volatility 110% 85% 81% Risk-free interest rate 1.38-2.54 2.39% - 2.95% 1.82% - 2.38% Expected term of options (years) 4.8 6.0 6.1 Expected dividend yield — — —
Schedule of share-based compensation expense	Share-based compensation expense includes expenses related to stock options and RSUs granted to employees, non-employee directors and consultants, as well as the option granted to employees to purchase shares under the ESPP, all of which have been reported in the Company’s Statements of Operations as follows: Years ended December 31, 2019 2018 2017 Research and development $ 4,260 $ 4,967 $ 11,114 General and administrative 4,920 6,105 7,057 Total $ 9,180 $ 11,072 $ 18,171

Net Loss Per Common Share (Tabl

Net Loss Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted net income (loss) per common share	The following table sets forth the computation of basic and diluted net income (loss) per common share for the periods indicated: Years ended December 31, 2019 2018 2017 Basic and diluted net income (loss) per common share calculation: Net income (loss) $ (58,859 ) $ 63,087 $ 114,205 Weighted average common shares outstanding - basic 42,224 37,061 35,919 Plus: net effect of dilutive stock options and unvested restricted stock units — 27 88 Weighted average common shares outstanding - dilutive 42,224 37,088 36,007 Net income (loss) per common share - basic $ (1.39 ) $ 1.70 $ 3.18 Net income (loss) per common share - diluted $ (1.39 ) $ 1.70 $ 3.17
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: Years ended December 31, 2019 2018 2017 Stock options outstanding 6,780 5,873 5,179 Restricted stock units 1,481 601 182 Total 8,261 6,474 5,361

Fair Value Measurements - (Tabl

Fair Value Measurements - (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of assets and liabilities that are measured at fair value on a recurring basis	The following table presents, for each of the fair value hierarchy levels required under ASC 820, the Company's assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2019 : Fair Value Measurement Using Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets Investments in money market funds* $ 108,585 $ — $ — Investments in corporate debt securities* $ — $ 13,875 $ — The following table presents, for each of the fair value hierarchy levels required under ASC 820, the Company's assets and liabilities that are measured at fair value on a recurring basis as of December 31, 2018 : Fair Value Measurement Using Quoted prices in active markets for identical assets (Level 1) Significant other observable inputs (Level 2) Significant unobservable inputs (Level 3) Assets Investments in money market funds* $ 97,402 $ — $ — Investments in corporate debt securities* — 29,425 — * Investments in money market funds and corporate debt securities with maturities less than 90 days are reflected in cash and cash equivalents in the accompanying Balance Sheets.

Licensing and Commercializati_2

Licensing and Commercialization Agreement (Tables)	12 Months Ended
	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of collaboration revenue components	Below is a summary of the components of the Company's collaboration revenue for the years ended December 31, 2019 , 2018 , and 2017 : Years ended December 31, 2019 2018 2017 License revenue $ — $ — $ 152,912 Research and development activity revenue — — 56,180 API transfer revenue — — 754 Joint operating committee revenue — — 131 Total collaboration revenue $ — $ — $ 209,977

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Schedule of property and equipment	Property and equipment as of December 31, 2019 and 2018 were as follows: Useful Life (Years) December 31, December 31, Manufacturing and clinical equipment 7 - 10 $ 47 $ 412 Computer, software and other office equipment 5 933 933 980 1,345 Accumulated depreciation (807 ) (1,010 ) Property and equipment, net $ 173 $ 335

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of reconciliation of the statutory U.S. federal rate to the Company's effective tax rate	A reconciliation of the statutory U.S. federal rate to the Company's effective tax rate is as follows: Years ended December 31, 2019 2018 2017 Percent of pre-tax income: U.S. federal statutory income tax rate 21.0 % 21.0 % 35.0 % State taxes, net of federal benefit 10.9 % 18.5 % 14.6 % Permanent items (1.0 )% 4.0 % 4.0 % Remeasurement of deferred tax assets — % — % 49.9 % Impact of state rate changes 0.1 % (0.2 )% (27.9 )% Research and development credit 2.8 % (2.4 )% — % Alternative minimum tax credit — % — % (1.3 )% Change in valuation allowance (33.6 )% (42.6 )% (78.6 )% Effective income tax rate 0.2 % (1.7 )% (4.3 )%
Schedule of components of income tax (benefit) expense	The components of income tax benefit are as follows: Years ended December 31, 2019 2018 2017 Current: Federal $ — $ — $ 173 State (111 ) (1,063 ) (1,356 ) Deferred: Federal — — (3,529 ) State — — — Income tax benefit $ (111 ) $ (1,063 ) $ (4,712 )
Schedule of significant components of the Company's deferred tax assets (liabilities)	Significant components of the Company's deferred tax assets (liabilities) for 2019 and 2018 consist of the following: As of December 31, 2019 2018 Deferred tax assets (liabilities) License and technology payments 7,116 7,221 Share-based compensation 22,131 20,342 Accrued expenses 362 371 Right-of-use asset (163 ) — Lease obligation 162 — Depreciation (18 ) (28 ) Federal and state net operating loss carryforwards 105,375 88,766 Research and development credits 7,353 5,933 Other 6 5 Deferred income tax assets 142,324 122,610 Valuation allowance (142,324 ) (122,610 ) Net deferred tax assets $ — $ —
Schedule of position with respect to uncertain tax positions	The Company's position with respect to uncertain tax positions is set forth below: Opening balance $ 13,983 Gross amount of increases in unrecognized tax benefits during the period - current year provisions — Gross amount of increases in unrecognized tax benefits during the period - prior year provisions 18 Gross amount of decreases in unrecognized tax benefits during the period - other (1,579 ) Decreases due to settlement with tax authorities during the period (195 ) Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period — Closing Balance $ 12,227

Operating Leases (Tables)

Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Schedule of Operating Lease Liability Maturities	The following presents the maturity of the Company's operating lease liabilities as of December 31, 2019 : December 31, 2019 2020 $ 504 Total remaining obligation $ 504 Less imputed interest $ (9 ) Present value of lease liabilities $ 495

Stock-Based Compensation and _2

Stock-Based Compensation and Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
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 and exercisable as of December 31, 2019 , 2018 and 2017 is as follows (in thousands except weighted average exercise price): Years ended December 31, 2019 2018 2017 Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Common Stock Options Weighted Average Exercise Price Outstanding, December 31, 2018 5,903 $ 13.72 5,284 $ 19.58 3,359 $ 39.92 Granted 1,610 $ 4.26 1,293 $ 1.67 3,024 $ 3.50 Exercised (80 ) $ 2.66 — $ — (20 ) $ 1.64 Expired or forfeited (653 ) $ 21.16 (674 ) $ 36.54 (1,079 ) $ 38.17 Outstanding, December 31, 2019 6,780 $ 10.89 5,903 $ 13.72 5,284 $ 19.58 Years ended December 31, 2019 2018 2017 Options exercisable at December 31, 2019 3,317 2,709 1,954 Weighted average grant date fair value (per share) of options granted during the period $ 3.37 $ 1.20 $ 2.45
Summary of the stock options outstanding and exercisable	A summary of the stock options outstanding and exercisable as of December 31, 2019 is as follows (in thousands except exercise prices and weighted average exercise price): December 31, 2019 Options Outstanding Options Exercisable Range of Exercise Prices Total Options Outstanding Weighted Average Remaining Life (Years) Weighted Average Exercise Price Number Exercisable Weighted Average Exercise Price $1.13-$2.79 1,350 8.8 $ 1.59 433 $ 1.76 $2.80-$2.96 1,725 7.9 $ 2.93 876 $ 2.93 $2.97-$4.87 1,444 8.1 $ 4.18 648 $ 4.48 $4.88-$31.09 1,090 8.7 $ 7.13 216 $ 14.89 $31.10-$73.22 1,171 5.1 $ 45.14 1,144 $ 45.01 6,780 7.8 $ 10.89 3,317 $ 18.38 Aggregate Intrinsic Value $ 28,475 $ 10,557
Schedule of cash proceeds from, and the aggregate intrinsic value of, stock options exercised	Cash proceeds from, and the aggregate intrinsic value of, stock options exercised during the years ended December 31, 2019 , 2018 and 2017 , respectively, were as follows: Years ended December 31, 2019 2018 2017 Cash proceeds from options exercised $ 192 $ — $ 33 Aggregate intrinsic value of options exercised $ 135 $ — $ 43
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 December 31, 2019 (in thousands except weighted average grant-date fair value): Restricted Stock Units Weighted Average Grant-Date Fair Value Outstanding, December 31, 2018 679 $ 15.61 Awarded 1,090 $ 4.57 Vested (255 ) $ 13.94 Forfeited (33 ) $ 16.35 Outstanding, December 31, 2019 1,481 $ 7.79

Selected Quarterly Financial _2

Selected Quarterly Financial Information (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Quarterly Financial Information Disclosure [Abstract]
Summary of the quarterly results of operations	The following is a summary of the quarterly results of operations for the years ended December 31, 2019 and 2018 : 2019 March 31 June 30 September 30 December 31 Research and development expenses 7,685 10,009 10,383 11,567 General and administrative expenses 5,481 5,198 4,674 6,275 Loss from operations (13,166 ) (15,207 ) (15,057 ) (17,842 ) Net income (loss) attributable to common stockholders $ (12,501 ) $ (14,443 ) $ (14,437 ) $ (17,478 ) Basic earnings (loss) per common share $ (0.30 ) $ (0.35 ) $ (0.35 ) $ (0.39 ) Diluted earnings (loss) per common share $ (0.30 ) $ (0.35 ) $ (0.35 ) $ (0.39 ) 2018 March 31 June 30 September 30 December 31 Research and development expenses 7,686 8,516 9,407 16,128 General and administrative expenses 5,645 6,332 5,968 5,667 Income (loss) from operations (13,331 ) (14,848 ) (15,375 ) (21,795 ) Net income (loss) attributable to common stockholders $ (13,073 ) $ (13,209 ) $ (14,745 ) $ 104,114 Basic earnings (loss) per common share $ (0.36 ) $ (0.37 ) $ (0.41 ) $ 2.62 Diluted earnings (loss) per common share $ (0.36 ) $ (0.37 ) $ (0.41 ) $ 2.62

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Segment and Geographic Information (Details)	12 Months Ended
	Dec. 31, 2019segment
Accounting Policies [Abstract]
Number of operating segments	1
Number of reporting segments	1

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Cash and cash equivalents	$ 125,699	$ 131,201

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2019
Minimum
Property and equipment
Estimated useful lives	3 years
Maximum
Property and equipment
Estimated useful lives	10 years

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Share-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Apr. 30, 2016
Share-Based Compensation
Expected dividend yield	0.00%
Share-based compensation expense	$ 9,180	$ 11,072	$ 18,171
Research and development
Share-Based Compensation
Share-based compensation expense	4,260	4,967	11,114
General and administrative
Share-Based Compensation
Share-based compensation expense	4,920	6,105	$ 7,057
ESPP
Share-Based Compensation
Share-based compensation expense	$ 100	$ 0
ESPP | Maximum
Share-Based Compensation
Number of shares reserved for issuance under the Plan (in shares)				1,000,000

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Schedule of Weighted-Average Assumptions (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
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	110.00%	85.00%	81.00%
Risk-free interest rate, minimum	1.38%	2.39%	1.82%
Risk-free interest rate, maximum	2.54%	2.95%	2.38%
Expected term of options (years)	4 years 9 months 6 days	6 years 6 days	6 years 1 month 6 days
Expected dividend yield	0.00%	0.00%	0.00%

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Recently Adopted Accounting Pronouncements (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets, net	$ 496
Operating lease liability	$ 495	$ 1,500
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets, net		1,500
Operating lease liability		$ 1,500
Weighted average estimated incremental borrowing rate		6.00%

Common Stock - Narrative (Detai

Common Stock - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 06, 2019	Jul. 22, 2019	Jul. 31, 2019
Class of Stock [Line Items]
Payments of stock issuance costs	$ 3
Payment of other stock issuance costs	0.4
Sale of stock, consideration received on transaction	$ 42.6
Public Stock Offering
Class of Stock [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	6,250,000
Sale of stock, price per share (in dollars per share)	$ 4
Number of warrants issued (in shares)	3,750,000
Warrant price (USD per share)	$ 3.999
Over-Allotment Option
Class of Stock [Line Items]
Sale of stock, number of shares issued in transaction (in shares)	1,500,000
Sale of stock, price per share (in dollars per share)	$ 3.736
Warrant price (USD per share)	$ 3.735
License Agreements | University Of Massachusetts (UMass) | miniCEP290
Class of Stock [Line Items]
Shares issued for license fees (in shares)		75,000	75,000
Shares issued for license agreement (in shares)		100,000

Net Income (Loss) Per Common _2

Net Income (Loss) Per Common Share - Schedule of Basic and Diluted Net Income (Loss) Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Basic and diluted net loss per common share calculation:
Net income (loss)									$ (58,859)	$ 63,087	$ 114,205
Weighted average common shares outstanding - basic (in shares)									42,224	37,061	35,919
Plus: net effect of dilutive stock options and unvested restricted stock units (in shares)									0	27	88
Weighted average common shares outstanding - dilutive (in shares)									42,224	37,088	36,007
Net income (loss) per common share - basic (USD per share)	$ (0.39)	$ (0.35)	$ (0.35)	$ (0.30)	$ 2.62	$ (0.41)	$ (0.37)	$ (0.36)	$ (1.39)	$ 1.70	$ 3.18
Net income (loss) per common share - diluted (USD per share)	$ (0.39)	$ (0.35)	$ (0.35)	$ (0.30)	$ 2.62	$ (0.41)	$ (0.37)	$ (0.36)	$ (1.39)	$ 1.70	$ 3.17

Net Income (Loss) Per Common _3

Net Income (Loss) Per Common Share - Schedule of Potentially Dilutive Securities (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total (in shares)	8,261	6,474	5,361
Stock options outstanding
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total (in shares)	6,780	5,873	5,179
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total (in shares)	1,481	601	182

Cash and Cash Equivalents - Nar

Cash and Cash Equivalents - Narrative (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 125,699,000	$ 131,201,000
Cash	3,200,000	4,400,000
Cash equivalents	122,500,000	126,800,000
Available for sale debt securities	$ 0	$ 0

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Fair Value Measurements
Transfer of assets from Level 1 to Level 2 of the fair value measurement hierarchy	$ 0	$ 0
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Money market funds
Fair Value Measurements
Investments in money market funds	108,585,000	97,402,000
Recurring basis | Quoted prices in active markets for identical assets (Level 1) | Corporate debt securities
Fair Value Measurements
Investments in money market funds	0	0
Recurring basis | Significant other observable inputs (Level 2) | Money market funds
Fair Value Measurements
Investments in money market funds	0	0
Recurring basis | Significant other observable inputs (Level 2) | Corporate debt securities
Fair Value Measurements
Investments in money market funds	13,875,000	29,425,000
Recurring basis | Significant unobservable inputs (Level 3) | Money market funds
Fair Value Measurements
Investments in money market funds	0	0
Recurring basis | Significant unobservable inputs (Level 3) | Corporate debt securities
Fair Value Measurements
Investments in money market funds	$ 0	$ 0

Inception 4 Acquisition (Detail

Inception 4 Acquisition (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	Oct. 30, 2018	Oct. 31, 2018	Dec. 31, 2018
Schedule Of Asset Acquisition [Line Items]
Share price (USD per share)		$ 2.26
Non-cash charge on acquired in-process research and development			$ 6.9
Transaction costs			$ 1.3
Inception 4
Schedule Of Asset Acquisition [Line Items]
Number of shares issued in asset acquisition (in shares)		5.2
Value of shares issued in asset acquisition		$ 11.7
Contingent consideration	$ 105	$ 105
Contingently issuable shares, asset acquisition (in shares)	7.2	7.2
Contingently issuable shares, asset acquisition, as a percentage of total shares outstanding	19.90%	19.90%
Cash acquired in asset acquisition		$ 6.1
GA | Inception 4
Schedule Of Asset Acquisition [Line Items]
Clinical and marketing approval milestones	$ 45
Wet AMD | Inception 4
Schedule Of Asset Acquisition [Line Items]
Clinical and marketing approval milestones	$ 60

Licensing and Commercializati_3

Licensing and Commercialization Agreement (Details) $ in Thousands

Jul. 22, 2019shares

Sep. 30, 2019USD ($)

Jul. 31, 2019shares

May 31, 2019USD ($)licensed_productshares

Jun. 30, 2018USD ($)

Aug. 31, 2017USD ($)

Jul. 31, 2017USD ($)

Jun. 30, 2016USD ($)

Mar. 31, 2015USD ($)

Sep. 30, 2014USD ($)

May 31, 2014USD ($)

Sep. 30, 2011USD ($)shares

Sep. 30, 2017USD ($)

Dec. 31, 2019USD ($)

Dec. 31, 2018USD ($)

Dec. 31, 2017USD ($)

Jun. 30, 2016USD ($)

Feb. 27, 2020USD ($)

Sep. 30, 2018USD ($)

Agreement

Number of licensed products | licensed_product

1

Upfront fees received

$ 16,900

Total collaboration revenue

$ 0

$ 0

$ 209,977

License revenue

Agreement

Total collaboration revenue

0

0

152,912

Research and development activity revenue

Agreement

Total collaboration revenue

0

0

56,180

API transfer revenue

Agreement

Total collaboration revenue

0

0

754

Joint operating committee revenue

Agreement

Total collaboration revenue

0

$ 0

$ 131

RHO-adRP License Agreement | University of Florida Research Foundation (UFRF) | Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product

Agreement

Amount to be paid on achievement of milestone

$ 23,500

RHO-adRP License Agreement | University of Florida Research Foundation (UFRF) | Specified Commercial Sales Milestones Related to a Licensed Product

Agreement

Amount to be paid on achievement of milestone

$ 70,000

BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn)

Agreement

Licensing agreement term

10 years

Licensing and Commercialization Agreement | Novartis Pharma AG

Agreement

Upfront fees received

$ 189,800

$ 200,000

Total collaboration revenue

$ 206,700

Licensing and Commercialization Agreement | Novartis Pharma AG | Achievement of specified patient enrollment milestones

Agreement

Patient enrollment-based milestone revenue achieved

$ 30,000

$ 50,000

$ 50,000

$ 130,000

Research and development | RHO-adRP License Agreement | University of Florida Research Foundation (UFRF)

Agreement

Payments for license fees

$ 500

Research and development | RHO-adRP License Agreement | University of Florida Research Foundation (UFRF) | Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product

Agreement

Payments for license fees

23,500

Research and development | RHO-adRP License Agreement | University of Florida Research Foundation (UFRF) | Specified Commercial Sales Milestones Related to a Licensed Product

Agreement

Payments for license fees

70,000

Research and development | BEST1 License Agreement | University Of Pennsylvania | Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product | Primary Licensed Product

Agreement

Payments for license fees

$ 200

Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product | Primary Licensed Product

Agreement

Payments for license fees

15,700

Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product | Other Licensed Product

Agreement

Payments for license fees

3,100

Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Specified Commercial Sales Milestones Related to a Licensed Product | Primary Licensed Product

Agreement

Payments for license fees

48,000

Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Specified Commercial Sales Milestones Related to a Licensed Product | Other Licensed Product

Agreement

Payments for license fees

9,600

General and administrative | RHO-adRP License Agreement | University of Florida Research Foundation (UFRF)

Agreement

Payments for license fees

$ 30

General and administrative | BEST1 License Agreement | University of Florida Research Foundation (UFRF) | Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product | Primary Licensed Product

Agreement

Payments for license fees

18

License Agreements | Archemix | C5 Licensed Product

Agreement

Licensing agreement term

12 years

License Agreements | Archemix | Achievement of specified clinical and regulatory milestones | C5 Licensed Product

Agreement

Payments for license fees

$ 1,000

Amount to be paid on achievement of milestone

$ 1,000

License Agreements | Archemix | First indication | C5 Licensed Product

Agreement

Amount to be paid on achievement of milestone

30,500

License Agreements | Archemix | Second and third indication | C5 Licensed Product

Agreement

Amount to be paid on achievement of milestone

23,500

License Agreements | Archemix | Sustained delivery applications | C5 Licensed Product

Agreement

Amount to be paid on achievement of milestone

$ 2,500

License Agreements | University Of Massachusetts (UMass) | miniCEP290

Agreement

Shares issued for license fees (in shares) | shares

75,000

75,000

Licensing agreement term

10 years

License Agreements | Research and development | University Of Massachusetts (UMass) | miniCEP290

Agreement

Payments for license fees

$ 400

License Agreements | Research and development | University Of Massachusetts (UMass) | Achievement of specified clinical and regulatory milestones | miniCEP290

Agreement

Payments for license fees

$ 14,750

Shares issued for license fees (in shares) | shares

75,000

License Agreements | Research and development | University Of Massachusetts (UMass) | Specified Commercial Sales Milestones Related to a Licensed Product | miniCEP290

Agreement

Payments for license fees

$ 48,000

License Agreements | General and administrative | University Of Massachusetts (UMass) | miniCEP290

Agreement

Payments for license fees

$ 0

License Agreements | Series A Preferred Stock | Archemix | Achievement of specified clinical and regulatory milestones | C5 Licensed Product

Agreement

Shares issued for license fees (in shares) | shares

2,000,000

License Agreements | Series B Preferred Stock | Archemix | Achievement of specified clinical and regulatory milestones | C5 Licensed Product

Agreement

Shares issued for license fees (in shares) | shares

500,000

Subsequent Event | License Agreements | Archemix | Achievement of specified clinical and regulatory milestones | C5 Licensed Product

Agreement

Payments for license fees

$ 2,000

Maximum | License Agreements | Archemix | Achievement of specified clinical and regulatory milestones | C5 Licensed Product

Agreement

Amount to be paid on achievement of milestone

$ 56,500

Maximum | License Agreements | Archemix | First indication | C5 Licensed Product

Agreement

Amount to be paid on achievement of milestone

30,500

Maximum | License Agreements | Archemix | Second and third indication | C5 Licensed Product

Agreement

Amount to be paid on achievement of milestone

23,500

Maximum | License Agreements | Archemix | Sustained delivery applications | C5 Licensed Product

Agreement

Amount to be paid on achievement of milestone

2,500

Maximum | License Agreements | Archemix | Achievement of specified commercial milestones | C5 Licensed Product

Agreement

Amount to be paid on achievement of milestone

$ 22,500

Financing Agreement with Novo_2

Financing Agreement with Novo Holdings A/S (Details)	1 Months Ended			12 Months Ended			19 Months Ended
	Nov. 30, 2014USD ($)	Jan. 31, 2014USD ($)	May 31, 2013USD ($)tranche	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Nov. 30, 2014USD ($)
Agreement
Gain on extinguishment of Royalty Purchase Liability				$ 0	$ 125,000,000	$ 0
Novo A/S | Novo Agreement | Fovista, Fovista-Related Products, and Other Products
Agreement
Number of tranches in financing | tranche			3
Aggregate royalty rights			$ 125,000,000
Proceeds from royalty purchase agreement	$ 41,700,000	$ 41,700,000	41,700,000				$ 125,000,000
Royalty purchase liability			$ 125,000,000

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property and Equipment
Property and equipment, gross	$ 980	$ 1,345
Accumulated depreciation	(807)	(1,010)
Property and equipment, net	173	335
Depreciation expense	$ 162	183	$ 2,763
Minimum
Property and Equipment
Useful life	3 years
Maximum
Property and Equipment
Useful life	10 years
Manufacturing and clinical equipment
Property and Equipment
Property and equipment, gross	$ 47	412
Manufacturing and clinical equipment | Minimum
Property and Equipment
Useful life	7 years
Manufacturing and clinical equipment | Maximum
Property and Equipment
Useful life	10 years
Computer, software and other office equipment
Property and Equipment
Useful life	5 years
Property and equipment, gross	$ 933	$ 933

Income Taxes - Schedule of Effe

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Percent of pre-tax income:
U.S. federal statutory income tax rate	21.00%	21.00%	35.00%
State taxes, net of federal benefit	10.90%	18.50%	14.60%
Permanent items	(1.00%)	4.00%	4.00%
Remeasurement of deferred tax assets	0.00%	0.00%	49.90%
Impact of state rate changes	0.10%	(0.20%)	(27.90%)
Research and development credit	2.80%	(2.40%)	(0.00%)
Alternative minimum tax credit	0.00%	0.00%	(1.30%)
Change in valuation allowance	(33.60%)	(42.60%)	(78.60%)
Effective income tax rate	0.20%	(1.70%)	(4.30%)

Income Taxes - Schedule of Comp

Income Taxes - Schedule of Components of Income Tax (Benefit) Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
Federal	$ 0	$ 0	$ 173
State	(111)	(1,063)	(1,356)
Deferred:
Federal	0	0	(3,529)
State	0	0	0
Income tax benefit	$ (111)	$ (1,063)	$ (4,712)

Income Taxes - Schedule of Sign

Income Taxes - Schedule of Significant Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax assets (liabilities)
License and technology payments	$ 7,116	$ 7,221
Share-based compensation	22,131	20,342
Accrued expenses	362	371
Right-of-use asset	(163)
Lease obligation	162
Depreciation	(18)	(28)
Federal and state net operating loss carryforwards	105,375	88,766
Research and development credits	7,353	5,933
Other	6	5
Deferred income tax assets	142,324	122,610
Valuation allowance	(142,324)	(122,610)
Net deferred tax assets	$ 0	$ 0

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Income tax benefit	$ 111,000	$ 1,063,000	$ 4,712,000
Tax Cuts and Jobs Act, income tax expense			3,500,000
Proceeds from income tax refunds	1,800,000
Income taxes receivable	1,800,000
Reduction in deferred tax assets and corresponding valuation allowance	19,700,000
Refund claimed for taxes previously paid	4,800,000
Minimum
Operating Loss Carryforwards [Line Items]
Estimate of unrecognized tax benefits that may be realized over the next twelve months	0
Maximum
Operating Loss Carryforwards [Line Items]
Estimate of unrecognized tax benefits that may be realized over the next twelve months	4,800,000
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Federal net operating loss carryforwards	$ 369,700,000
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Settlement of state franchise tax audit			$ 1,400,000

Income Taxes - Schedule of Posi

Income Taxes - Schedule of Position with Respect to Uncertain Tax Positions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Opening balance	$ 13,983
Gross amount of increases in unrecognized tax benefits during the period - current year provisions	0
Gross amount of increases in unrecognized tax benefits during the period - prior year provisions	18
Gross amount of decreases in unrecognized tax benefits during the period - other	(1,579)
Decreases due to settlement with tax authorities during the period	(195)
Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period	0
Closing Balance	$ 12,227

Operating Leases - Narrative (D

Operating Leases - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Feb. 29, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use asset		$ 496
Operating lease liability		495			$ 1,500
Operating lease rent expense		1,000
Operating lease rent expense			$ 800	$ 3,600
Cash paid from operating cash flows		$ 1,000
Operating lease, weighted average remaining lease term		6 months
Operating right-of-use assets obtained in exchange for lease obligations		$ 1,469
ASU 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use asset					1,500
Operating lease liability					$ 1,500
Weighted average estimated incremental borrowing rate					6.00%
Subsequent Event
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating right-of-use assets obtained in exchange for lease obligations	$ 200

Operating Leases - Schedule of

Operating Leases - Schedule of Operating Lease Liability Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 01, 2019
Future minimum rental commitments under non-cancelable operating leases
2020	$ 504
Total remaining obligation	504
Less imputed interest	(9)
Present value of lease liabilities	$ 495	$ 1,500

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Thousands	Jul. 22, 2019shares	Mar. 12, 2019USD ($)	Oct. 30, 2018USD ($)shares	Sep. 30, 2019USD ($)	Jul. 31, 2019shares	May 31, 2019USD ($)licensed_productshares	Oct. 31, 2018USD ($)shares	Jun. 30, 2018USD ($)	Sep. 30, 2011USD ($)	Dec. 31, 2019USD ($)	Sep. 30, 2018USD ($)
Commitments and contingencies
Number of licensed products | licensed_product						1
Litigation settlement awared to other party		$ 300
License Agreements | Archemix | C5 Licensed Product | Achievement of specified clinical and regulatory milestones
Commitments and contingencies
Amount to be paid on achievement of milestone										$ 1,000
Payments for license fees									$ 1,000
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
Commitments and contingencies
Amount to be paid on achievement of milestone									30,500
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
Commitments and contingencies
Amount to be paid on achievement of milestone									23,500
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
Commitments and contingencies
Amount to be paid on achievement of milestone									2,500
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
License Agreements | University Of Massachusetts (UMass) | miniCEP290
Commitments and contingencies
Shares issued for license fees (in shares) | shares	75,000				75,000
RHO-adRP License Agreement | University of Florida Research Foundation (UFRF) | Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related 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 Related to a Licensed Product
Commitments and contingencies
Amount to be paid on achievement of milestone											$ 70,000
Inception 4
Commitments and contingencies
Contingent consideration			$ 105,000				$ 105,000
Contingently issuable shares, asset acquisition (in shares) | shares			7,200,000				7,200,000
Contingently issuable shares, asset acquisition, as a percentage of total shares outstanding			19.90%				19.90%
Inception 4 | GA
Commitments and contingencies
Clinical and marketing approval milestones			$ 45,000
Inception 4 | Wet AMD
Commitments and contingencies
Clinical and marketing approval milestones			$ 60,000
Research and development | License Agreements | University Of Massachusetts (UMass) | miniCEP290
Commitments and contingencies
Payments for license fees				$ 400
Research and development | 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 | License Agreements | University Of Massachusetts (UMass) | miniCEP290 | Specified Commercial Sales Milestones Related to a Licensed Product
Commitments and contingencies
Payments for license fees						$ 48,000
Research and development | RHO-adRP License Agreement | University of Florida Research Foundation (UFRF)
Commitments and contingencies
Payments for license fees								$ 500
Research and development | RHO-adRP License Agreement | University of Florida Research Foundation (UFRF) | Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product
Commitments and contingencies
Payments for license fees								23,500
Research and development | RHO-adRP License Agreement | University of Florida Research Foundation (UFRF) | Specified Commercial Sales Milestones Related to a Licensed Product
Commitments and contingencies
Payments for license fees								$ 70,000
Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Primary Licensed Product | Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product
Commitments and contingencies
Payments for license fees						15,700
Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Primary Licensed Product | Specified Commercial Sales Milestones Related to a Licensed Product
Commitments and contingencies
Payments for license fees						48,000
Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Other Licensed Product | Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product
Commitments and contingencies
Payments for license fees						3,100
Research and development | BEST1 License Agreement | University Of Florida Research Foundation (UFRF) And University Of Pennsylvania (Penn) | Other Licensed Product | Specified Commercial Sales Milestones Related to a Licensed Product
Commitments and contingencies
Payments for license fees						$ 9,600

Stock-Based Compensation and _3

Stock-Based Compensation and Compensation Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	Jan. 01, 2020	Apr. 30, 2016	Aug. 31, 2013	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Oct. 31, 2019
Stock Option and Compensation Plans
Options outstanding (in shares)				6,468,000
Weighted-average exercise price of options (in dollars per share)				$ 11.24
Weighted-average remaining contractual life of options				7 years 8 months 18 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value				$ 10,600
Share-based compensation expense				$ 9,180	$ 11,072	$ 18,171
Shares issued under ESPP (in shares)					31,413
ESPP
Stock Option and Compensation Plans
Number of shares of common stock available for issuance under the Plan (in shares)				881,763
Purchase price of common stock as percentage of fair market value		85.00%
Share-based compensation expense				$ 100	$ 0
Expected weighted average period to recognize share-based compensation costs				3 months 18 days
Common stock issued (in shares)				70,466
Proceeds from stock plans				$ 81
Restricted stock units
Stock Option and Compensation Plans
Share-based compensation expense				$ 0	100
RSUs expected to vest (in shares)				1,287,000
Weighted-average fair value of RSUs expected to vest (in dollars per share)				$ 5.39
Aggregate intrinsic value of RSUs expected to vest				$ 11,000
Total fair value vested				3,600
Employees | Stock options
Stock Option and Compensation Plans
Share-based compensation expense				5,900	7,600	13,100
Unrecognized share-based compensation costs for option awards, net of estimated forfeitures				$ 8,000
Expected weighted average period to recognize share-based compensation costs				3 years 1 month 6 days
Employees | Restricted stock units
Stock Option and Compensation Plans
Share-based compensation expense				$ 3,000	3,300	4,400
Expected weighted average period to recognize share-based compensation costs				2 years 8 months 18 days
Unrecognized compensation costs, net of estimated forfeitures				$ 5,000
Consultants | Non-employee Options
Stock Option and Compensation Plans
Share-based compensation expense				300	$ 200	$ 300
Unrecognized share-based compensation costs for option awards, net of estimated forfeitures				$ 200
Expected weighted average period to recognize share-based compensation costs				3 years 7 months 12 days
Consultants | Restricted stock units
Stock Option and Compensation Plans
Expected weighted average period to recognize share-based compensation costs				3 years 5 months
Unrecognized compensation costs, net of estimated forfeitures				$ 100
Maximum | ESPP
Stock Option and Compensation Plans
Number of shares reserved for issuance under the Plan (in shares)		1,000,000
2013 Plan
Stock Option and Compensation Plans
Number of shares of common stock available for issuance under the Plan (in shares)				732,000
Annual increase in shares reserved for issuance under the Plan (in shares)			2,542,372
Annual increase in shares reserved for issuance under the Plan (as a percent)			4.00%
Increase in number of shares available under the Plan (in shares)				10,539,000
2013 Plan | Subsequent Event
Stock Option and Compensation Plans
Annual increase in shares reserved for issuance under the Plan (as a percent)	4.00%
Increase in number of shares available under the Plan (in shares)	1,985,000
2013 Plan | Maximum
Stock Option and Compensation Plans
Number of shares reserved for issuance under the Plan (in shares)			3,359,641
2007 Plan
Stock Option and Compensation Plans
Number of shares of common stock available for issuance under the Plan (in shares)			739,317
2019 Inducement Plan | Stock options
Stock Option and Compensation Plans
Number of shares reserved for issuance under the Plan (in shares)							1,000,000
Number of shares of common stock available for issuance under the Plan (in shares)							650,000

Stock-Based Compensation and _4

Stock-Based Compensation and Compensation Plans - Summary of Stock Option Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Common Stock Options
Outstanding at beginning of year (in shares)	5,903	5,284	3,359
Granted (in shares)	1,610	1,293	3,024
Exercised (in shares)	(80)	0	(20)
Expired or forfeited (in shares)	(653)	(674)	(1,079)
Outstanding at end of year (in shares)	6,780	5,903	5,284
Weighted Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 13.72	$ 19.58	$ 39.92
Granted (in dollars per share)	4.26	1.67	3.50
Exercised (in dollars per share)	2.66	0	1.64
Expired or forfeited (in dollars per share)	21.16	36.54	38.17
Outstanding at end of year (in dollars per share)	$ 10.89	$ 13.72	$ 19.58
Options exercisable at end of year (in shares)	3,317	2,709	1,954
Weighted average grant date fair value (per share) of options granted during the period (in dollars per share)	$ 3.37	$ 1.20	$ 2.45

Stock-Based Compensation and _5

Stock-Based Compensation and Compensation Plans - Options Outstanding and Exercisable by Exercise Price and Options Exercised (Details) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)$ / sharesshares
Options Outstanding
Total Options Outstanding (in shares) | shares	6,780
Weighted Average Remaining Life (Years)	7 years 9 months 24 days
Weighted Average Exercise Price (in dollars per share)	$ 10.89
Aggregate Intrinsic Value of Options Outstanding | $	$ 28,475
Options Exercisable
Number Exercisable (in shares) | shares	3,317
Weighted Average Exercise Price (in dollars per share)	$ 18.38
Aggregate Intrinsic Value of Options Exercisable | $	$ 10,557
$1.13-$2.79
Range of Exercise Prices
Exercise prices, low end of range (in dollars per share)	$ 1.13
Exercise prices, high end of range (in dollars per share)	$ 2.79
Options Outstanding
Total Options Outstanding (in shares) | shares	1,350
Weighted Average Remaining Life (Years)	8 years 9 months 18 days
Weighted Average Exercise Price (in dollars per share)	$ 1.59
Options Exercisable
Number Exercisable (in shares) | shares	433
Weighted Average Exercise Price (in dollars per share)	$ 1.76
$2.80-$2.96
Range of Exercise Prices
Exercise prices, low end of range (in dollars per share)	2.80
Exercise prices, high end of range (in dollars per share)	$ 2.96
Options Outstanding
Total Options Outstanding (in shares) | shares	1,725
Weighted Average Remaining Life (Years)	7 years 11 months
Weighted Average Exercise Price (in dollars per share)	$ 2.93
Options Exercisable
Number Exercisable (in shares) | shares	876
Weighted Average Exercise Price (in dollars per share)	$ 2.93
$2.97-$4.87
Range of Exercise Prices
Exercise prices, low end of range (in dollars per share)	2.97
Exercise prices, high end of range (in dollars per share)	$ 4.87
Options Outstanding
Total Options Outstanding (in shares) | shares	1,444
Weighted Average Remaining Life (Years)	8 years 1 month 24 days
Weighted Average Exercise Price (in dollars per share)	$ 4.18
Options Exercisable
Number Exercisable (in shares) | shares	648
Weighted Average Exercise Price (in dollars per share)	$ 4.48
$4.88-$31.09
Range of Exercise Prices
Exercise prices, low end of range (in dollars per share)	4.88
Exercise prices, high end of range (in dollars per share)	$ 31.09
Options Outstanding
Total Options Outstanding (in shares) | shares	1,090
Weighted Average Remaining Life (Years)	8 years 8 months 24 days
Weighted Average Exercise Price (in dollars per share)	$ 7.13
Options Exercisable
Number Exercisable (in shares) | shares	216
Weighted Average Exercise Price (in dollars per share)	$ 14.89
$31.10-$73.22
Range of Exercise Prices
Exercise prices, low end of range (in dollars per share)	31.10
Exercise prices, high end of range (in dollars per share)	$ 73.22
Options Outstanding
Total Options Outstanding (in shares) | shares	1,171
Weighted Average Remaining Life (Years)	5 years 1 month 6 days
Weighted Average Exercise Price (in dollars per share)	$ 45.14
Options Exercisable
Number Exercisable (in shares) | shares	1,144
Weighted Average Exercise Price (in dollars per share)	$ 45.01

Stock-Based Compensation and _6

Stock-Based Compensation and Compensation Plans - Schedule of Cash Proceeds From and Aggregate Intrinsic Value of Stock Options Exercised (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Payment Arrangement [Abstract]
Cash proceeds from options exercised	$ 192	$ 0	$ 33
Aggregate intrinsic value of options exercised	$ 135	$ 0	$ 43

Stock-Based Compensation and _7

Stock-Based Compensation and Compensation Plans - Summary of Outstanding RSU Awards Granted (Details) - Restricted stock units shares in Thousands	12 Months Ended
	Dec. 31, 2019$ / sharesshares
Restricted Stock Units
Outstanding, beginning of period (in shares) | shares	679
Awarded (in shares) | shares	1,090
Vested (in shares) | shares	(255)
Forfeited (in shares) | shares	(33)
Outstanding, end of period (in shares) | shares	1,481
Weighted Average Grant-Date Fair Value
Outstanding, beginning of period (in dollars per share) | $ / shares	$ 15.61
Awarded (in dollars per share) | $ / shares	4.57
Vested (in dollars per share) | $ / shares	13.94
Forfeited (in dollars per share) | $ / shares	16.35
Outstanding, end of period (in dollars per share) | $ / shares	$ 7.79

Employee Benefit Plan (Details)

Employee Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Retirement Benefits [Abstract]
Defined contribution plan, cost recognized	$ 0.2	$ 0.2	$ 0.7

Selected Quarterly Financial _3

Selected Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Research and development expenses	$ 11,567	$ 10,383	$ 10,009	$ 7,685	$ 16,128	$ 9,407	$ 8,516	$ 7,686	$ 39,644	$ 41,737	$ 66,289
General and administrative expenses	6,275	4,674	5,198	5,481	5,667	5,968	6,332	5,645	21,628	23,612	35,683
Income (loss) from operations	(17,842)	(15,057)	(15,207)	(13,166)	(21,795)	(15,375)	(14,848)	(13,331)	$ (61,272)	$ (65,349)	$ 108,005
Net income (loss) attributable to common stockholders	$ (17,478)	$ (14,437)	$ (14,443)	$ (12,501)	$ 104,114	$ (14,745)	$ (13,209)	$ (13,073)
Basic (in dollars per share)	$ (0.39)	$ (0.35)	$ (0.35)	$ (0.30)	$ 2.62	$ (0.41)	$ (0.37)	$ (0.36)	$ (1.39)	$ 1.70	$ 3.18
Dilutive (in dollars per share)	$ (0.39)	$ (0.35)	$ (0.35)	$ (0.30)	$ 2.62	$ (0.41)	$ (0.37)	$ (0.36)	$ (1.39)	$ 1.70	$ 3.17