View Filing Data

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2018	Feb. 25, 2019	Jun. 29, 2018
Document And Entity Information
Entity Registrant Name	Ophthotech Corp.
Entity Central Index Key	0001410939
Document Type	10-K
Document Period End Date	Dec. 31, 2018
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			$ 98.5
Entity Common Stock, Shares Outstanding		41,421,548
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets
Cash and cash equivalents	$ 131,201	$ 166,972
Prepaid expenses and other current assets	2,086	3,146
Income tax receivable	0	1,387
Total current assets	133,287	171,505
Property and equipment, net	335	518
Income tax receivable, non-current	3,529	0
Deferred tax assets	0	3,529
Other assets	14	24
Total assets	137,165	175,576
Current liabilities
Accrued research and development expenses	7,337	4,984
Accounts payable and accrued expenses	5,869	7,551
Total current liabilities	13,206	12,535
Royalty purchase liability	0	125,000
Total liabilities	13,206	137,535
Stockholders' equity
Preferred stock—$0.001 par value, 5,000,000 shares authorized, no shares issued or outstanding	0	0
Common stock—$0.001 par value, 200,000,000 shares authorized, 41,397,197 and 36,110,298 shares issued and outstanding at December 31, 2018 and December 31, 2017, respectively	41	36
Additional paid-in capital	545,585	522,759
Accumulated deficit	(421,667)	(484,754)
Total stockholders' equity	123,959	38,041
Total liabilities and stockholders' equity	$ 137,165	$ 175,576

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	41,397,197	36,110,298
Common stock, shares outstanding (in shares)	41,397,197	36,110,298

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Collaboration revenue	$ 0	$ 209,977	$ 50,909
Operating expenses:
Research and development	41,737	66,289	196,295
General and administrative	23,612	35,683	50,178
Total operating expenses	65,349	101,972	246,473
Income (loss) from operations	(65,349)	108,005	(195,564)
Interest income	2,389	1,522	1,704
Gain on extinguishment of Royalty Purchase Liability	125,000	0	0
Other income (expense)	(16)	(34)	34
Income (loss) before income tax benefit	62,024	109,493	(193,826)
Income tax benefit	(1,063)	(4,712)	(406)
Net income (loss)	$ 63,087	$ 114,205	$ (193,420)
Net income (loss) per common share:
Basic (in dollars per share)	$ 1.70	$ 3.18	$ (5.45)
Dilutive (in dollars per share)	$ 1.70	$ 3.17	$ (5.45)
Weighted average common shares outstanding:
Basic (in shares)	37,061	35,919	35,486
Dilutive (in shares)	37,088	36,007	35,486

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ 63,087	$ 114,205	$ (193,420)
Other comprehensive income
Unrealized gain on available for sale securities, net of tax	0	212	261
Other comprehensive income	0	212	261
Comprehensive income (loss)	$ 63,087	$ 114,417	$ (193,159)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

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, 2015		0	35,197
Balance at beginning of period at Dec. 31, 2015	$ 59,947	$ 0	$ 35	$ 465,924	$ (405,539)	$ (473)
Increase (Decrease) in Stockholders' Equity
Issuance of common stock under employee stock compensation plans and warrants (in shares)			536
Issuance of common stock under employee stock compensation plans and warrants	6,934		$ 1	6,933
Share-based compensation	0
Excess tax benefit from share-based compensation	0
Net loss	(193,420)				(193,420)
Unrealized gain on available for sale securities, net of tax	261					261
Balance at end of period (in shares) at Dec. 31, 2016		0	35,733
Ending balance 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			71
Share-based compensation	18,171			18,171
Net loss	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 under employee stock compensation plans and warrants (in shares)			112
Issuance of common stock under employee stock compensation plans and warrants	65			65
Issuance of common stock related to acquisition (in shares)			5,175
Issuance of common stock related to acquisition	11,694		$ 5	11,689
Share-based compensation	11,072			11,072
Net loss	63,087				63,087
Unrealized gain on available for sale securities, net of tax	0					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

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities
Net income (loss)	$ 63,087	$ 114,205	$ (193,420)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities
Depreciation	183	2,763	757
Amortization of premium and discounts on investment securities	0	140	595
Non-cash charge on acquired in-process research and development	5,619	0	0
Non-cash gain on extinguishment of royalty purchase agreement	(125,000)	0	0
Deferred income taxes	0	(3,366)	22,954
Share-based compensation	11,072	18,171	31,660
Changes in operating assets and liabilities:
Income tax receivable	1,387	(1,387)	3,421
Due from Novartis Pharma AG	0	3,531	858
Prepaid expense and other current assets	1,060	(68)	(995)
Accrued interest receivable	0	466	203
Other assets	10	438	27
Accrued research and development expenses	2,353	(42,256)	28,420
Accounts payable and accrued expenses	(1,682)	(4,481)	14
Deferred revenue	0	(209,977)	(3,090)
Net cash used in operating activities	(41,911)	(121,821)	(108,596)
Investing Activities
Purchase of marketable securities	0	(12,014)	(72,197)
Maturities of marketable securities	0	166,806	86,500
Purchase of property and equipment	0	0	(572)
Net cash provided by investing activities	0	154,792	13,731
Financing Activities
Proceeds from issuance of common stock related to acquisition	6,075	0	0
Proceeds from employee stock plan purchases and stock option exercises	65	71	6,934
Net cash provided by financing activities	6,140	71	6,934
Net change in cash and cash equivalents	(35,771)	33,042	(87,931)
Cash and cash equivalents
Beginning of period	166,972	133,930	221,861
End of period	131,201	166,972	133,930
Supplemental disclosure of cash paid
Income taxes received, net	(2,467)	(245)	(26,998)
Supplemental disclosures of non-cash information related to investing activities
Change in unrealized gain (loss) on available for sale securities, net of tax	0	212	261
Common stock issued to acquire net assets of Inception 4, Inc.	$ 11,694	$ 0	$ 0

Business

12 Months Ended

Dec. 31, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Business

Description of Business and Organization

Ophthotech Corporation (the “Company” or “Ophthotech”) was incorporated on January 5, 2007, in Delaware. The Company is a science-driven biopharmaceutical company specializing in the development of novel therapies to treat ophthalmic diseases, with a focus on age-related and orphan retinal diseases. The Company is seeking to leverage its development platform, clinical experience and retina expertise to develop both therapeutics and gene therapies in these disease areas.

The Company currently has ongoing research and development programs for both therapeutics and gene therapy product candidates and technologies.

The Company's therapeutics portfolio consists of Zimura® (avacincaptad pegol), which is a C5 complement inhibitor, and its program of High temperature requirement A serine peptidase 1 protein ("HtrA1") inhibitors. The Company has Phase 2b clinical trials ongoing evaluating Zimura for the treatment of:


•	geographic atrophy ("GA"), which is a late-stage form of dry age-related macular degeneration ("AMD") characterized by retinal cell death and degeneration of tissue in the central portion of the retina, referred to as the macula, and which may result in loss of vision; and


•	autosomal recessive Stargardt disease, which is an orphan inherited retinal disease ("IRD") that also may result in 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 it completed a Phase 2a clinical trial during the fourth quarter of 2018. The Company does not currently have plans to develop Zimura further in wet AMD. The Company's HtrA1 inhibitor program, which it is developing for GA secondary to dry AMD and potentially other retinal diseases such as wet AMD and idiopathic polypoidal choroidal vasculopathy, is in the preclinical stage of development.

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;


•	Best vitelliform macular dystrophy which is characterized by bilateral egg yolk-like macular lesions that, over time, progress to atrophy and loss of vision, and potentially other diseases associated with mutations in the Best1 gene, which is referred to as bestrophinopathies;


•	Leber Congenital Amaurosis type 10, which is characterized by severe bilateral loss of vision at or soon after birth; and


•	autosomal recessive Stargardt disease.

The Company's business development efforts in 2018 have resulted in the expansion of its research and development pipeline, with the initiation of the Company's gene therapy sponsored research programs with the University of Massachusetts Medical School ("UMMS") in February 2018, the in-license of the Company's RHO-adRP gene therapy product candidate in June 2018 from the University of Florida Research Foundation ("UFRF") and the University of Pennsylvania ("Penn"), the acquisition of its HtrA1 inhibitor program through the acquisition of Inception 4, Inc. ("Inception 4") in October 2018 (See Note 5—Inception 4 Acquisition for a description of this acquisition) and the entry into its exclusive option agreement with Penn and UFRF for gene therapy product candidates for bestrophinopathies in October 2018.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

sis 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 Ophthotech 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, 2018, the Company had cash and cash equivalents of approximately $131.2 million. The Company believes that its existing cash and cash equivalents as of December 31, 2018 will be sufficient to fund its operations and capital expenditure requirements as currently planned for at least the next 12 months.

Revenue Recognition

Collaboration Revenue

Prior to 2018, the Company's revenue resulted from payments received under its May 2014 licensing and commercialization agreement (the “Novartis Agreement”) with Novartis Pharma AG ("Novartis"), as modified by the July 2017 letter agreement entered into by the Company and Novartis in relation to the Novartis Agreement (the "July 2017 Letter Agreement"). See "Note 6—Licensing and Commercialization Agreements" below for a description of these agreements. 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.

As the Company has no products approved for sale, the Company does not expect to receive any revenue from product candidates that it develops until it potentially obtains regulatory approval and commercializes such products, or until the Company potentially enters into agreements with third parties for the development and commercialization of its product candidates. If the Company's development efforts for any of its product candidates result in regulatory approval or the Company enters into collaboration agreements with third parties, the Company may generate revenue from product sales or from such third parties.

In the future, the Company will evaluate revenue contracts and arrangements, if any, following the provisions of the Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC"), Revenue from Contracts with Customers (Topic 606).

Business combinations and asset acquisitions

The Company evaluates acquisitions of assets and other similar transactions to assess whether or not the transaction should be accounted for as a business combination or asset acquisition by first applying a screen (as adopted in the current period under Accounting Standards Update (ASU) No. 2017-01, "Business Combinations (Topic 805): Clarifying the Definition of a Business"—see "Recently Adopted Accounting Standards" for further details) to determine if substantially all of the fair value of the gross assets acquired is concentrated in a single identifiable asset or group of similar identifiable assets. If the screen is met, the transaction is accounted for as an asset acquisition. If the screen is not met, further determination is required as to whether or not the Company has acquired inputs and processes that have the ability to create outputs, which would meet the requirements of a business. If determined to be a business combination, the Company records all assets and liabilities of the acquired business, including goodwill and other identified intangible assets, at their respective fair values as of the acquisition date. Contingent consideration, if any, is recognized at its fair value on the acquisition date and changes in fair value are recognized in earnings until settlement. Acquisition-related transaction costs are expensed as incurred.

If determined to be an asset acquisition, the Company accounts for the transaction under ASC 805-50, which requires the acquiring entity in an asset acquisition to recognize assets (net assets) based on the cost to the acquiring entity on a relative fair value basis, which includes transaction costs in addition to consideration given. No gain or loss is recognized as of the date of acquisition unless the fair value of noncash assets given as consideration differs from the assets' carrying amounts on the acquiring entity's books. Consideration transferred that is noncash will be measured based on either the cost (which shall be measured based on the fair value of the consideration given) or the fair value of the assets (net assets) acquired, whichever is more reliably measurable. Goodwill is not recognized in an asset acquisition and any excess consideration transferred over the fair value of the net assets acquired is allocated to the identifiable assets based on relative fair values. In-process research and development acquired in connection with an asset acquisition is expensed in accordance with FASB ASC 730, Research and Development, when there is no alternative future use.

Contingent consideration payments in asset acquisitions are recognized when the contingency is resolved and the consideration is paid or becomes payable (unless the contingent consideration meets the definition of a derivative, in which case the amount becomes part of the basis in the asset acquired). Upon recognition of the contingent consideration payment, the amount is included in the cost of the acquired asset or group of assets.

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, 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 supplies of the active pharmaceutical ingredient ("API") for Zimura on a purchase order basis. The Company also engages a single third-party manufacturer to provide fill/finish services for clinical supplies of Zimura. In addition, the Company currently relies upon a single third-party supplier to supply it with the proprietary polyethylene glycol reagent used to manufacture Zimura on a purchase order basis. Furthermore, the Company and its contract manufacturers currently rely upon sole-source suppliers of certain raw materials and other specialized components of production used in the manufacture and fill/finish of Zimura. The Company has engaged a single third-party contract manufacturer for its RHO-adRP gene therapy product candidate and expects to rely on sole-source suppliers for certain starting materials to be used in the manufacture of such product candidate. The Company has recently engaged a single third-party contract manufacturer for the BEST1 gene therapy product candidate for which it is planning to commence IND-enabling studies and expects to rely on sole-source suppliers for certain starting materials to be used in the manufacture of such product candidate. If the Company’s third-party manufacturers, fill/finish service providers or starting material suppliers should become unavailable to the Company for any reason, including as a result of capacity constraints, financial difficulties or insolvency, the Company believes that there are a limited number of potential replacement manufacturers or suppliers, 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 Statements of Operations. 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.

Property and Equipment

Property and equipment, which consists mainly of manufacturing and clinical equipment, furniture and fixtures, computers, software, and 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 expenses primarily consist of costs associated with the manufacturing, development and clinical testing of Zimura and, historically, Fovista, as well as costs associated with the preclinical development of other product candidates, formulations and technologies, including costs associated with its HtrA1 inhibitor program, costs associated with its RHO-adRP gene therapy product candidate, including related sponsored research with Penn, costs associated with the BEST1 gene therapy product candidate for which the Company is planning to commence IND-enabling studies, and costs associated with its ongoing gene therapy sponsored research programs with UMMS. 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 other vendors and contract manufacturing organizations ("CMOs") for the production of drug substance and drug product; and


•	employee-related expenses for employees dedicated to research and development activities, including salaries, benefits and share-based compensation expense.

Research and development expenses also include costs of acquired product licenses, in-process research and development, and related technology rights where there is no alternative future use, costs of prototypes used in research and development, consultant fees and amounts paid to collaborative partners.

The Company expects its research and development expenses to increase as the Company pursues the development of Zimura, its HtrA1 inhibitor program, its RHO-adRP gene therapy product candidate and the BEST1 gene therapy product candidates for which it holds an option from Penn and UFRF. The Company also expects to incur research and development expenses in connection with its collaborative gene therapy sponsored research programs. As the Company pursues its ongoing and planned Zimura, HtrA1 inhibitor, RHO-adRP and BEST1 development programs and its collaborative gene therapy sponsored research programs, or as the Company commences any new development efforts in relation to additional product candidates that the Company may in-license or acquire as it pursues its business plan, the Company expects that its overall research and development expenses will increase from the current level of expenditure.

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.

Share-Based Compensation

The Company follows the provisions of ASC 718, Compensation—Stock Compensation, which requires the measurement and recognition of compensation expense for all share-based payment awards made to employees and non-employee directors, including employee stock options, restricted stock units (“RSUs”) and the option 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.

Stock Options

The Company estimates the fair value of stock options granted to employees and non-employee directors on the date of grant using the Black-Scholes option-pricing model. Due to the lack of trading history, the Company's computation of stock-price volatility is based on the volatility rates of comparable publicly held companies over a period equal to the expected term of the options granted by the Company. The Company's computation of expected term is determined using the "simplified" method, which is the midpoint between the vesting date and the end of the contractual term. The Company believes that it does not have sufficient reliable exercise data in order to justify the use of a method other than the "simplified" method of estimating the expected exercise term of employee stock option grants. The Company utilizes a dividend yield of zero based on the fact that the Company has never paid cash dividends to stockholders and has no current intentions to pay cash dividends. The risk-free interest rate is based on the zero-coupon U.S. Treasury yield at the date of grant for a term equivalent to the expected term of the option.

For stock options granted as consideration for services rendered by consultants, the Company recognizes expense in accordance with the requirements of ASC 505-50, Equity Based Payments to Non-Employees. Consultant stock option grants are recorded as an expense over the vesting period of the underlying stock options. At the end of each financial reporting period prior to vesting, the value of these options, as calculated using the Black-Scholes option-pricing model, will be re-measured using the fair value of the Company's common stock and the non-cash expense recognized during the period will be adjusted accordingly. Since the fair value of options granted to consultants is subject to change in the future, the amount of the future expense will include fair value re-measurements until the stock options are fully vested.

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, 2018, 2017 and 2016:



	Years ended December 31,
	2018	2017	2016
Expected common stock price volatility	85%	81%	71%
Risk-free interest rate	2.39% - 2.95%	1.82% - 2.38%	1.14% - 2.37%
Expected term of options (years)	6.0	6.1	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 board of directors adopted the ESPP pursuant to which the Company may sell up to an aggregate of 1,000,000 shares of common stock. The ESPP was approved by the Company’s stockholders in June 2016. The ESPP is considered compensatory and the fair value of the discount and look back provision are estimated using the Black-Scholes option-pricing model and recognized over the six month withholding period prior to purchase.

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,
	2018		2017		2016
Research and development	$	4,967	$	11,114	$	21,380
General and administrative	6,105		7,057		10,280
Total	$	11,072	$	18,171	$	31,660

Recently Adopted Accounting Pronouncements

In May 2014, the FASB issued ASC 606, Revenue from Contracts with Customers (“ASC 606”). ASC 606 outlines a new, single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. This new revenue recognition model provides a five-step analysis in determining when and how revenue is recognized. The new model requires revenue recognition to depict the transfer of promised goods or services to customers in an amount that reflects the consideration a company expects to receive in exchange for those goods or services. On January 1, 2018, the Company adopted this guidance using the modified retrospective approach. Due to the termination of the Novartis Agreement and the Company's current lack of other revenue sources, the Company's financial statements were not impacted by adoption of this standard. The future impact of ASC 606 will be dependent on the nature of the Company’s future revenue contracts and arrangements, if any.

In August 2016, the FASB issued Accounting Standards Update (ASU) No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, which clarifies the presentation of certain specific cash flow issues in the Statement of Cash Flows. For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2017, and interim periods within those annual periods. Early adoption is permitted. Starting with the three months ended March 31, 2018, the Company adopted this guidance. The adoption did not have a material impact on the Company's financial statements.

In January 2017, the FASB issued ASU No. 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business, in an effort to clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The amendments of this ASU are effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years. Early adoption is permitted. This new guidance was applicable for the acquisition of Inception 4 and will be applicable for any other acquisitions by the Company on or after January 1, 2018.

Recent 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 ASC 606. The new lease guidance simplified the accounting for sale and leaseback transactions primarily because lessees must recognize lease assets and lease liabilities. Lessees will no longer be provided with a source of off-balance sheet financing. Publicly-traded business entities should apply the amendments in ASU 2016-2 for fiscal years beginning after December 15, 2018 (i.e., January 1, 2019, for a calendar year entity), including interim periods within those fiscal years. Early application is permitted for all publicly-traded business entities and all non-publicly-traded business entities upon issuance. Lessees (for capital and operating leases) and lessors (for sales-type, direct financing, and operating leases) must apply a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. The modified retrospective approach would not require any transition accounting for leases that expired before the earliest comparative period presented. Lessees and lessors may not apply a full retrospective transition approach. The Company has assessed the impact of adopting this new accounting guidance on its financial statements and footnote disclosures. As such, the Company expects the most significant impact will be the recognition of right-of-use assets and lease liabilities of approximately $1.5 million on its Consolidated Balance Sheet.

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 payment arrangements related to the acquisition of goods and services from both employees and nonemployees. For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2018, including interim periods within those annual periods. Early adoption is permitted, but no earlier than a company's adoption date of ASC 606. The Company is currently assessing the impact that adopting this new accounting guidance will have on its financial statements and footnote disclosures.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820), which modifies the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, including, among other changes, the consideration of costs and benefits when evaluating disclosure requirements. For public companies, the amendments are effective for annual reporting periods beginning after December 15, 2019, including interim periods within those annual periods. Early adoption is permitted. The Company is currently assessing the impact that adopting this new accounting guidance will have on its financial statements and footnote disclosures.

In August 2018, the FASB issued ASU No. 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract (a consensus of the FASB Emerging Issues Task Force). ASU 2018-15 aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal-use software license). This guidance is effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years, with early adoption permitted.The Company is currently assessing the impact that adopting this new accounting guidance will have on its financial statements and footnote 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 is currently assessing the impact that adopting this new accounting guidance will have on its financial statements and footnote disclosures.

Net Income (Loss) Per Common Share

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

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 outstanding during the period. For the periods when there is a net loss, stock options and RSUs have been excluded from the calculation of diluted net loss per common share because their effect 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,
	2018		2017		2016
Basic and diluted net income (loss) per common share calculation:
Net income (loss)	$	63,087	$	114,205	$	(193,420	)
Weighted average common shares outstanding - basic	37,061		35,919		35,486
Plus: net effect of dilutive stock options and unvested restricted stock units	27		88		—
Weighted average common shares outstanding - dilutive	37,088		36,007		35,486
Net income (loss) per common share - basic	$	1.70	$	3.18	$	(5.45	)
Net income (loss) per common share - diluted	$	1.70	$	3.17	$	(5.45	)

The following potentially dilutive securities have been excluded from the computations of diluted weighted average common shares outstanding for the periods presented, as they would be anti-dilutive:



	Years ended December 31,
	2018	2017	2016
Stock options outstanding	5,873	5,179	3,359
Restricted stock units	601	182	721
Total	6,474	5,361	4,080

Cash and Cash Equivalents

12 Months Ended

Dec. 31, 2018

Cash and Cash Equivalents [Abstract]

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. Cash and cash equivalents included cash of $4.4 million and $9.5 million at December 31, 2018 and 2017, respectively. Cash and cash equivalents at December 31, 2018 and December 31, 2017 also included $126.8 million and $157.4 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 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, 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	$	—



	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*	$	162,457	$	—	$	—


*	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, 2018 or December 31, 2017.

Inception 4 Acquisition	12 Months Ended
Inception 4 Acquisition	Dec. 31, 2018
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, a Delaware corporation, 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 acquisition date closing price of the Company’s common stock of $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, 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 believes the cash it acquired in connection with its acquisition of Inception 4 will be sufficient to fund the majority of anticipated development costs associated with the development of the HtrA1 inhibitor program through the IND submission stage. 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 Agreement

12 Months Ended

Dec. 31, 2018

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Licensing and Commercialization Agreement

Licensing and Commercialization Agreements

RHO-adRP Gene Therapy Agreements with the University of Florida and the University of Pennsylvania

In June 2018, the Company entered into an exclusive global license agreement (the "RHO-adRP License Agreement") with UFRF and Penn (collectively, 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 a novel AAV gene therapy product candidate intended to treat RHO-adRP (the "RHO-adRP Licensed Product").

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 with respect to such licensed product 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 U.S. Food and Drug Administration ("FDA") in connection with obtaining marketing approval for a licensed product and the Company subsequently uses such priority review voucher in connection with a different product candidate or sells such priority review voucher, the Company will be obligated to make certain payments to UFRF, on behalf of both Licensors.

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 agreed to a Master-Sponsored Research Agreement (the "MSRA"), facilitated by the Penn Center for Innovation. Under the MSRA, the Company and Penn are conducting additional preclinical studies for the RHO-adRP Licensed Product, as well as a natural history study of RHO-adRP patients.

Prior Licensing and Commercialization Agreement with Novartis Pharma AG

Prior to 2018, the Company's revenue 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, 2018, 2017, and 2016:



	Years ended December 31,
	2018		2017		2016
License revenue	$	—	$	152,912	$	22,937
Research and development activity revenue	—		56,180		9,741
API transfer revenue	—		754		18,212
Joint operating committee revenue	—		131		19
Total collaboration revenue	$	—	$	209,977	$	50,909

Financing Agreement with Novo Holdings A/S	12 Months Ended
Financing Agreement with Novo Holdings A/S	Dec. 31, 2018
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 (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 Holdings A/S 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"). Pursuant to the Novo Agreement, 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, and Novo Holdings A/S received, in the aggregate, a right to receive royalties on net sales of Fovista at a mid-single digit percentage. 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 Holdings A/S, the Company treated its obligation to make royalty payments under the Novo Agreement as an implicit obligation to repay the funds advanced by Novo Holdings A/S. On December 31, 2018, the Company and Novo Holdings A/S entered into a letter agreement (the "Novo Termination Agreement"), that terminated the Novo Agreement. As a result of the Novo Termination Agreement, Novo Holdings A/S 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 or affiliate any right or license in any such intellectual property rights or clinical study data generated by or on behalf of the Company, its affiliates or 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 Anti-PDGF Royalty Products without the prior written consent of Novo Holdings A/S. 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 legal 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. As the Company had received the proceeds related to the royalty purchase liability in prior periods, the extinguishment of the royalty purchase liability and the related gain did not impact the Company's cash balance during this period.

Property and Equipment

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property and Equipment

Property and equipment as of December 31, 2018 and 2017 were as follows:



	Useful Life (Years)	December 31, 2018			December 31, 2017
Manufacturing and clinical equipment	7 - 10	$	412		$	412
Computer, software and other office equipment	5	933			933
		1,345			1,345
Accumulated depreciation		(1,010		)	(827		)
Property and equipment, net		$	335		$	518

For the years ended December 31, 2018, 2017 and 2016, depreciation expense was $0.2 million, $2.8 million and $0.8 million, respectively.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

In December 2017, the U.S. Tax Cuts and Jobs Act (“TCJA”) was enacted reducing the corporate tax rate from 35% to 21% effective for tax years beginning on or after January 1, 2018. ASC 740, Income Taxes requires the effects of changes in tax laws to be recognized in the period in which the legislation is enacted. However, due to the complexity and significance of the TCJA’s provisions, the SEC staff issued SAB 118, which allows companies to record the tax effects of the TCJA on a provisional basis based on a reasonable estimate, and then, if necessary, subsequently adjust such amounts during a limited measurement period as more information becomes available. The Company recorded provisional amounts and has subsequently finalized its accounting analysis based on the guidance, interpretations, and data available as of December 31, 2018.

Under the TCJA, the Corporate Alternative Minimum Tax ("AMT") was repealed. The Company's previously recorded AMT credits of approximately $3.5 million are now refundable over a four-year period beginning in 2018 and the previously recorded valuation allowance for these AMT credits was reversed during the year ended December 31, 2017. The Company does not have any offshore earnings from which to record the mandatory transition tax.

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,
	2018		2017		2016
Percent of pre-tax income:
U.S. federal statutory income tax rate	21.0	%	35.0	%	35.0	%
State taxes, net of federal benefit	18.5	%	14.6	%	2.8	%
Permanent items	4.0	%	4.0	%	(1.4	)%
Remeasurement of deferred tax assets	—	%	49.9	%	—	%
Impact of state rate changes	(0.2	)%	(27.9	)%	(11.0	)%
Research and development credit	(2.4	)%	—	%	1.9	%
Alternative minimum tax credit	—	%	(1.3	)%	1.1	%
Change in valuation allowance	(42.6	)%	(78.6	)%	(28.2	)%
Effective income tax rate	(1.7	)%	(4.3	)%	0.2	%

The components of income tax benefit are as follows:



	Years ended December 31,
	2018			2017			2016
Current:
Federal	$	—		$	173		$	(23,393	)
State	(1,063		)	(1,356		)	21
Deferred:
Federal	—			(3,529		)	22,966
State	—			—			—
Income tax benefit	$	(1,063	)	$	(4,712	)	$	(406	)

Significant components of the Company's deferred tax assets (liabilities) for 2018 and 2017 consist of the following:



	As of December 31,
	2018			2017
Deferred tax assets (liabilities)
Deferred revenue	$	—		$	40,961
License and technology payments	7,221			8,222
Share-based compensation	20,342			17,599
Accrued expenses	371			608
Depreciation	(28		)	81
Federal and state net operating loss carryforwards	88,766			76,309
Research and development credits	5,933			3,782
Other	5			3,534
Deferred income tax assets	122,610			151,096
Valuation allowance	(122,610		)	(147,567		)
Net deferred tax assets	$	—		$	3,529

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 2018 and 2017. The Company realized its net deferred tax assets recorded as of December 31, 2017 in 2016 as a result of the Company’s carry back of its 2015 federal tax losses to 2014. The Company has carried forward its 2015 state tax losses due to various state restrictions on the use of carryback claims. The state NOLs are expected to begin to expire in 2027. Due to the Company’s history of losses and lack of other positive evidence to support taxable income after the 2014 tax year, the Company has recorded a valuation allowance against those remaining deferred tax assets that are not expected to be realized. As of December 31, 2018, the Company has federal NOL carryforwards of approximately $315.5 million. These losses are due to expire in 2036 and 2037.

For the year ended December 31, 2018, the Company recorded a benefit from income of $1.1 million which primarily related to the settlement of a local tax audit. For the year ended December 31, 2017, the Company recorded a benefit from income 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 2018, the Company reclassified the $3.5 million related to AMT credits to a non-current income tax receivable as it expects to receive the refunds over the next four years.

Although the Company generated net income before income taxes for the years ended December 31, 2018 and 2017, this income is 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, 2018.

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, 2018, the Company reduced certain deferred tax assets by $25.0 million and reduced 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 $5.0 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	$	16,881
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	17
Gross amount of decreases in unrecognized tax benefits during the period - other	(1,413		)
Decreases due to settlement with tax authorities during the period	(1,502		)
Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period	—
Closing Balance	$	13,983

As the Company is currently being audited 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 $5.0 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

12 Months Ended

Dec. 31, 2018

Leases [Abstract]

Operating Leases

The Company leases office space located in New York, New York and Princeton, New Jersey under operating lease arrangements. The lease for the Company's New York office space expires at the end of June 2020, whereas the sublease for the Company's Princeton office space expires in March 2020. Future minimum rental commitments under non-cancelable operating leases in effect as of December 31, 2018, are as follows:



2019	$	1,040
2020	504
Total	$	1,544

Rent expense is calculated on the straight-line basis and amounted to $0.8 million, $3.6 million and $3.0 million for the years ended December 31, 2018, 2017 and 2016, respectively.

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Archemix Corp. The Company is party to an agreement (the "C5 License Agreement") with Archemix Corp. ("Archemix"), under which the Company in-licensed rights in certain patents, patent applications and other intellectual property related to Zimura and pursuant to which the Company may be required to pay sublicense fees and make milestone payments. Under the C5 License Agreement, for each anti-C5 aptamer product that the Company may develop under the agreement, including Zimura, the Company is obligated to make payments to Archemix of up to an aggregate of $57.5 million if the Company achieves specified development, clinical and regulatory milestones, with $30.5 million of such payments relating to a first indication, $24.5 million of such payments relating to second and third indications and $2.5 million of such payments relating to sustained delivery applications. Under the C5 License Agreement, the Company is also obligated to make additional payments to Archemix of up to an aggregate of $22.5 million if the Company achieves specified commercial milestones based on net product sales of all anti-C5 products licensed under the agreement. The Company is also obligated to pay Archemix a double-digit percentage of specified non-royalty payments the Company may receive from any sublicensee of its rights under the C5 License Agreement. The Company is not obligated to pay Archemix a running royalty based on net product sales in connection with the C5 License Agreement. University of Florida and the University of Pennsylvania Under the RHO-adRP License Agreement, the Company is obligated to make payments to UFRF, on behalf of both 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, on behalf of both Licensors, a running royalty equal to a low single-digit percentage of net sales of licensed products. The Company is also obligated to pay UFRF, on behalf of both 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, on behalf of both 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. In addition, if the Company sells such a priority review voucher to a third party, the Company 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. 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, 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, CMOs and academic research institutions represent significant costs in preclinical and clinical development. Subject to required notice periods and the Company’s obligations under binding purchase orders and any cancellation fees that the Company may be obligated to pay, the Company can elect to discontinue the work under these agreements at any time. Legal Proceedings On January 11, 2017, a putative class action lawsuit was filed against the Company and certain of its current and former executive officers in the United States District Court for the Southern District of New York, captioned Frank Micholle v. Ophthotech Corporation, et al., No. 1:17-cv-00210. On March 9, 2017, a related putative class action lawsuit was filed against the Company and the same group of its current and former executive officers in the United States District Court for the Southern District of New York, captioned Wasson v. Ophthotech Corporation, et al., No. 1:17-cv-01758. These cases were consolidated on March 13, 2018. On June 4, 2018, the lead plaintiff filed a consolidated amended complaint (the “CAC”). The CAC purports to be brought on behalf of shareholders who purchased the Company’s common stock between March 2, 2015 and December 12, 2016. The CAC generally alleges that the Company and certain of its officers violated Sections 10(b) and/or 20(a) of the Securities Exchange Act of 1934 and Rule 10b-5 promulgated thereunder by making allegedly false and/or misleading statements concerning the results of the Company’s Phase 2b trial and the prospects of the Company’s Phase 3 trials for Fovista in combination with anti-VEGF agents for the treatment of wet AMD. The CAC seeks unspecified damages, attorneys’ fees, and other costs. The Company and individual defendants filed a motion to dismiss the CAC on July 27, 2018. That motion is fully briefed. On February 7, 2018, a shareholder derivative action was filed against the members of the Company’s Board of Directors in the New York Supreme Court Commercial Division, captioned Cano v. Guyer, et al., No. 650601/2018. The complaint alleges that the defendants breached their fiduciary duties to the Company by adopting a compensation plan that overcompensates the non-employee members of the 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. In addition, the Company expects it may be liable to pay approximately $0.3 million in fees to plaintiff's counsel. A hearing to determine whether the court will approve the settlement is scheduled for March 12, 2019. 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. The plaintiff filed its opposition to the motion to dismiss on February 22, 2019, and the Company’s reply is due on April 3, 2019. On October 16, 2018, the Company’s board of directors received a shareholder demand to investigate and commence legal proceedings against certain members of the Company’s board of directors. The demand alleges facts that are substantially similar to the facts alleged in the CAC and the Pacheco complaint and asserts claims that are substantially similar to the claims asserted in the Pacheco complaint. On January 30, 2019, the Company’s board of directors received a second shareholder demand from a different shareholder to investigate and commence legal proceedings against certain current and former members of the Company’s board of directors based on allegations that are substantially similar to the allegations contained in the first demand letter. The Company denies any and all allegations of wrongdoing and intends to vigorously defend against these lawsuits. The Company is unable, however, to predict the outcome of these matters at this time. Moreover, any conclusion of these matters in a manner adverse to the Company and for which it incurs substantial costs or damages not covered by the Company's directors’ and officers’ liability insurance would have a material adverse effect on its financial condition and business. In addition, the litigation could adversely impact the Company's reputation and divert management’s attention and resources from other priorities, including the execution of its business plan and strategies that are important to the Company's ability to grow its business, any of which could have a material adverse effect on the Company's business.

Stock Option and Compensation Plans

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock Option 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 8,554,000 additional shares to the 2013 Plan, including for 2019, an increase of approximately 1,656,000 shares, or 4% of the total number of shares of the Company's common stock outstanding as of January 1, 2019. As of December 31, 2018, the Company had approximately 840,000 shares available for grant under the 2013 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, 2018, 2017 and 2016 is as follows (in thousands except weighted average exercise price):



	Years ended December 31,
	2018				2017				2016
	Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price
Outstanding, December 31, 2017	5,284		$	19.58	3,359		$	39.92	3,009		$	30.43
Granted	1,293		$	1.67	3,024		$	3.50	972		$	60.40
Exercised	—		$	—	(20	)	$	1.64	(428	)	$	15.73
Expired or forfeited	(674	)	$	36.54	(1,079	)	$	38.17	(194	)	$	48.63
Outstanding, December 31, 2018	5,903		$	13.72	5,284		$	19.58	3,359		$	39.92



	Years ended December 31,
	2018		2017		2016
Options exercisable at December 31, 2018	2,709		1,954		1,531
Weighted average grant date fair value (per share) of options granted during the period	$	1.20	$	2.45	$	38.18

As of December 31, 2018, there were approximately 5,615,000 options outstanding, net of estimated forfeitures, that had vested or are expected to vest. The weighted-average exercise price of these options was $14.17 per option; the weighted-average remaining contractual life of these options was 7.8 years; and the aggregate intrinsic value of these options was de minimis. A summary of the stock options outstanding and exercisable as of December 31, 2018 is as follows (in thousands except exercise prices and weighted average exercise price):



			December 31, 2018
			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
$0.12-$10.03	4,231		8.8	$	3.07	1,174		$	4.20
$10.04-$20.00	133		4.5	$	13.68	133		$	13.68
$20.01-$30.00	114		4.4	$	24.69	114		$	24.69
$30.01-$40.00	680		4.4	$	33.12	680		$	33.12
$40.01-$55.00	508		6.6	$	46.61	420		$	46.48
$55.01-$73.22	237		7.0	$	72.32	188		$	72.09
	5,903		7.9	$	13.72	2,709		$	24.07

Aggregate Intrinsic Value	$	3				$	3

Cash proceeds from, and the aggregate intrinsic value of, stock options exercised during the years ended December 31, 2018, 2017 and 2016, respectively, were as follows:



	Years ended December 31,
	2018		2017		2016
Cash proceeds from options exercised	$	—	$	33	$	6,934
Aggregate intrinsic value of options exercised	$	—	$	43	$	14,439

In connection with stock option awards granted to employees, the Company recognized approximately $7.6 million, $13.1 million and $22.8 million in share-based compensation expense during the years ended December 31, 2018, 2017 and 2016, respectively, net of expected forfeitures. As of December 31, 2018, there were approximately $9.0 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 2.1 years.

In connection with stock option awards granted to consultants, the Company recognized approximately $0.2 million, $0.3 million and $1.7 million in share-based compensation expense during the years ended December 31, 2018, 2017 and 2016, respectively, net of expected forfeitures. As of December 31, 2018, 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 1.7 years.

The following table presents a summary of the Company's outstanding RSU awards granted as of December 31, 2018 (in thousands except weighted average grant-date fair value):



	Restricted Stock Units		Weighted Average Grant-Date Fair Value
Outstanding, December 31, 2017	327		$	51.08
Awarded	499		$	1.45
Vested	(80	)	$	46.25
Forfeited	(67	)	$	45.57
Outstanding, December 31, 2018	679		$	15.61

As of December 31, 2018, there were approximately 550,000 RSUs outstanding, net of estimated forfeitures, that are expected to vest. The weighted-average fair value of these RSUs was $10.36 per share; and the aggregate intrinsic value of these RSUs was approximately $0.7 million.

In connection with RSUs granted to employees, the Company recognized approximately $3.3 million, $4.4 million and $6.9 million in share-based compensation expense during the years ended December 31, 2018, 2017 and 2016, respectively, net of expected forfeitures. As of December 31, 2018, there was approximately $3.2 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 1.8 years. The total fair value of the RSUs that vested during the year ended December 31, 2018 was $3.4 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, 2018, net of expected forfeitures. In connection with RSUs granted to consultants, the Company recognized approximately $0.3 million in share-based compensation expense during the year ended December 31, 2017. As of December 31, 2018, 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 1.0 years.

In connection with the ESPP made available to employees, the Company recognized a de minimis amount and $0.1 million of share-based compensation expense during the years ended December 31, 2018 and December 31, 2017, respectively, net of expected forfeitures. As of December 31, 2018, 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 31,413 shares of common stock issued under the ESPP during the year ended December 31, 2018. Cash proceeds from ESPP purchases were $65 thousand during the year ended December 31, 2018. There were 16,358 shares of common stock issued under the ESPP during the year ended December 31, 2017. As of December 31, 2018, 952,229 shares were available for future purchases under the ESPP.

Employee Benefit Plan	12 Months Ended
Employee Benefit Plan	Dec. 31, 2018
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, $0.7 million and $0.8 million during the years ended December 31, 2018, 2017 and 2016, respectively.

Restructuring Activities

12 Months Ended

Dec. 31, 2018

Restructuring and Related Activities [Abstract]

Restructuring Activities

In December 2016, the Company announced its intention to implement a reduction in personnel to focus on an updated business plan. In January 2017, the board of directors approved a plan to implement a reduction in personnel involving approximately 80% of the Company’s workforce based on the number of employees at the time the plan was approved. The reduction in personnel was substantially completed during 2017 with a limited number of departing employees receiving severance payments during 2018.

As of December 31, 2018, the Company had completed its reduction in personnel and the payment of its remaining accrued severance and other employee costs. The following is a reconciliation of the severance-related accrual activity for the year ended December 31, 2018:



	Accrued Severance and Other Employee Costs
Beginning Balance	$	2,529
Accrued restructuring expenses	—
Payments	(2,529		)
Ending Balance	$	—

Selected Quarterly Financial Information (unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Information (unaudited)

The following is a summary of the quarterly results of operations for the years ended December 31, 2018 and 2017:



	2018
	March 31			June 30			September 30			December 31
Collaboration revenue	$	—		$	—		$	—		$	—
Research and development expenses	7,686			8,516			9,407			16,128
General and administrative expenses	5,645			6,332			5,968			5,667
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



	2017
	March 31			June 30			September 30		December 31
Collaboration revenue	$	1,662		$	1,661		$	206,654	$	—
Research and development expenses	31,979			15,657			10,707		7,946
General and administrative expenses	13,159			8,552			7,059		6,913
Income (loss) from operations	(43,476		)	(22,548		)	188,888		(14,859		)
Net income (loss) attributable to common stockholders	$	(43,122	)	$	(22,204	)	$	189,073	$	(9,542	)
Basic earnings (loss) per common share	$	(1.20	)	$	(0.62	)	$	5.26	$	(0.26	)
Diluted earnings (loss) per common share	$	(1.20	)	$	(0.62	)	$	5.25	$	(0.26	)

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation

Basis of Presentation and Consolidation

Basis of Consolidation

The consolidated financial statements include the accounts of Ophthotech and its subsidiaries. All intercompany balances and transactions have been eliminated in consolidation.

Segment and geographic information

Use of Estimates

Cash and Cash Equivalents

Revenue Recognition

Collaboration Revenue

Business combinations and asset acquisitions

Concentration of Credit Risk

The Company believes it is not exposed to significant credit risk on its cash and cash equivalents.

Concentration of Suppliers

Foreign Currency Translation

Financial Instruments

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.

Property and Equipment

Research and Development


•	external research and development expenses incurred under arrangements with third parties, such as academic research collaborators, contract research organizations ("CROs") and other vendors and contract manufacturing organizations ("CMOs") for the production of drug substance and drug product; and


•	employee-related expenses for employees dedicated to research and development activities, including salaries, benefits and share-based compensation expense.

Income Taxes

Share-Based Compensation

Stock Options



	Years ended December 31,
	2018	2017	2016
Expected common stock price volatility	85%	81%	71%
Risk-free interest rate	2.39% - 2.95%	1.82% - 2.38%	1.14% - 2.37%
Expected term of options (years)	6.0	6.1	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



	Years ended December 31,
	2018		2017		2016
Research and development	$	4,967	$	11,114	$	21,380
General and administrative	6,105		7,057		10,280
Total	$	11,072	$	18,171	$	31,660

Recently Adopted and Recent Accounting Pronouncements

Recently Adopted Accounting Pronouncements

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Schedule of weighted-average assumptions used to estimate grant date fair value of stock options



	Years ended December 31,
	2018	2017	2016
Expected common stock price volatility	85%	81%	71%
Risk-free interest rate	2.39% - 2.95%	1.82% - 2.38%	1.14% - 2.37%
Expected term of options (years)	6.0	6.1	6.1
Expected dividend yield	—	—	—

Schedule of share-based compensation expense



	Years ended December 31,
	2018		2017		2016
Research and development	$	4,967	$	11,114	$	21,380
General and administrative	6,105		7,057		10,280
Total	$	11,072	$	18,171	$	31,660

Net Loss Per Common Share (Tables)

12 Months Ended

Dec. 31, 2018

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,
	2018		2017		2016
Basic and diluted net income (loss) per common share calculation:
Net income (loss)	$	63,087	$	114,205	$	(193,420	)
Weighted average common shares outstanding - basic	37,061		35,919		35,486
Plus: net effect of dilutive stock options and unvested restricted stock units	27		88		—
Weighted average common shares outstanding - dilutive	37,088		36,007		35,486
Net income (loss) per common share - basic	$	1.70	$	3.18	$	(5.45	)
Net income (loss) per common share - diluted	$	1.70	$	3.17	$	(5.45	)

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 they would be anti-dilutive:



	Years ended December 31,
	2018	2017	2016
Stock options outstanding	5,873	5,179	3,359
Restricted stock units	601	182	721
Total	6,474	5,361	4,080

Cash and Cash Equivalents (Tables)

12 Months Ended

Dec. 31, 2018

Cash and Cash Equivalents [Abstract]

Schedule of assets and liabilities that are measured at fair value on a recurring basis



	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	$	—



	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*	$	162,457	$	—	$	—


*	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 Commercialization Agreement (Tables)

12 Months Ended

Dec. 31, 2018

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, 2018, 2017, and 2016:



	Years ended December 31,
	2018		2017		2016
License revenue	$	—	$	152,912	$	22,937
Research and development activity revenue	—		56,180		9,741
API transfer revenue	—		754		18,212
Joint operating committee revenue	—		131		19
Total collaboration revenue	$	—	$	209,977	$	50,909

Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Schedule of property and equipment

Property and equipment as of December 31, 2018 and 2017 were as follows:



	Useful Life (Years)	December 31, 2018			December 31, 2017
Manufacturing and clinical equipment	7 - 10	$	412		$	412
Computer, software and other office equipment	5	933			933
		1,345			1,345
Accumulated depreciation		(1,010		)	(827		)
Property and equipment, net		$	335		$	518

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

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,
	2018		2017		2016
Percent of pre-tax income:
U.S. federal statutory income tax rate	21.0	%	35.0	%	35.0	%
State taxes, net of federal benefit	18.5	%	14.6	%	2.8	%
Permanent items	4.0	%	4.0	%	(1.4	)%
Remeasurement of deferred tax assets	—	%	49.9	%	—	%
Impact of state rate changes	(0.2	)%	(27.9	)%	(11.0	)%
Research and development credit	(2.4	)%	—	%	1.9	%
Alternative minimum tax credit	—	%	(1.3	)%	1.1	%
Change in valuation allowance	(42.6	)%	(78.6	)%	(28.2	)%
Effective income tax rate	(1.7	)%	(4.3	)%	0.2	%

Schedule of components of income tax (benefit) expense

The components of income tax benefit are as follows:



	Years ended December 31,
	2018			2017			2016
Current:
Federal	$	—		$	173		$	(23,393	)
State	(1,063		)	(1,356		)	21
Deferred:
Federal	—			(3,529		)	22,966
State	—			—			—
Income tax benefit	$	(1,063	)	$	(4,712	)	$	(406	)

Schedule of significant components of the Company's deferred tax assets (liabilities)

Significant components of the Company's deferred tax assets (liabilities) for 2018 and 2017 consist of the following:



	As of December 31,
	2018			2017
Deferred tax assets (liabilities)
Deferred revenue	$	—		$	40,961
License and technology payments	7,221			8,222
Share-based compensation	20,342			17,599
Accrued expenses	371			608
Depreciation	(28		)	81
Federal and state net operating loss carryforwards	88,766			76,309
Research and development credits	5,933			3,782
Other	5			3,534
Deferred income tax assets	122,610			151,096
Valuation allowance	(122,610		)	(147,567		)
Net deferred tax assets	$	—		$	3,529

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	$	16,881
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	17
Gross amount of decreases in unrecognized tax benefits during the period - other	(1,413		)
Decreases due to settlement with tax authorities during the period	(1,502		)
Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period	—
Closing Balance	$	13,983

Operating Leases (Tables)

12 Months Ended

Dec. 31, 2018

Leases [Abstract]

Schedule of future minimum rental commitments under non-cancelable operating leases

Future minimum rental commitments under non-cancelable operating leases in effect as of December 31, 2018, are as follows:



2019	$	1,040
2020	504
Total	$	1,544

Stock Option and Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Summary of the stock option activity including weighted average exercise prices, options outstanding and exercisable



	Years ended December 31,
	2018				2017				2016
	Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price		Common Stock Options		Weighted Average Exercise Price
Outstanding, December 31, 2017	5,284		$	19.58	3,359		$	39.92	3,009		$	30.43
Granted	1,293		$	1.67	3,024		$	3.50	972		$	60.40
Exercised	—		$	—	(20	)	$	1.64	(428	)	$	15.73
Expired or forfeited	(674	)	$	36.54	(1,079	)	$	38.17	(194	)	$	48.63
Outstanding, December 31, 2018	5,903		$	13.72	5,284		$	19.58	3,359		$	39.92



	Years ended December 31,
	2018		2017		2016
Options exercisable at December 31, 2018	2,709		1,954		1,531
Weighted average grant date fair value (per share) of options granted during the period	$	1.20	$	2.45	$	38.18

Summary of the stock options outstanding and exercisable

A summary of the stock options outstanding and exercisable as of December 31, 2018 is as follows (in thousands except exercise prices and weighted average exercise price):



			December 31, 2018
			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
$0.12-$10.03	4,231		8.8	$	3.07	1,174		$	4.20
$10.04-$20.00	133		4.5	$	13.68	133		$	13.68
$20.01-$30.00	114		4.4	$	24.69	114		$	24.69
$30.01-$40.00	680		4.4	$	33.12	680		$	33.12
$40.01-$55.00	508		6.6	$	46.61	420		$	46.48
$55.01-$73.22	237		7.0	$	72.32	188		$	72.09
	5,903		7.9	$	13.72	2,709		$	24.07

Aggregate Intrinsic Value	$	3				$	3

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, 2018, 2017 and 2016, respectively, were as follows:



	Years ended December 31,
	2018		2017		2016
Cash proceeds from options exercised	$	—	$	33	$	6,934
Aggregate intrinsic value of options exercised	$	—	$	43	$	14,439

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, 2018 (in thousands except weighted average grant-date fair value):



	Restricted Stock Units		Weighted Average Grant-Date Fair Value
Outstanding, December 31, 2017	327		$	51.08
Awarded	499		$	1.45
Vested	(80	)	$	46.25
Forfeited	(67	)	$	45.57
Outstanding, December 31, 2018	679		$	15.61

Restructuring Activities (Tables)

12 Months Ended

Dec. 31, 2018

Restructuring and Related Activities [Abstract]

Reconciliation of severance-related accrual activity

The following is a reconciliation of the severance-related accrual activity for the year ended December 31, 2018:



	Accrued Severance and Other Employee Costs
Beginning Balance	$	2,529
Accrued restructuring expenses	—
Payments	(2,529		)
Ending Balance	$	—

Selected Quarterly Financial Information (unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

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, 2018 and 2017:



	2018
	March 31			June 30			September 30			December 31
Collaboration revenue	$	—		$	—		$	—		$	—
Research and development expenses	7,686			8,516			9,407			16,128
General and administrative expenses	5,645			6,332			5,968			5,667
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



	2017
	March 31			June 30			September 30		December 31
Collaboration revenue	$	1,662		$	1,661		$	206,654	$	—
Research and development expenses	31,979			15,657			10,707		7,946
General and administrative expenses	13,159			8,552			7,059		6,913
Income (loss) from operations	(43,476		)	(22,548		)	188,888		(14,859		)
Net income (loss) attributable to common stockholders	$	(43,122	)	$	(22,204	)	$	189,073	$	(9,542	)
Basic earnings (loss) per common share	$	(1.20	)	$	(0.62	)	$	5.26	$	(0.26	)
Diluted earnings (loss) per common share	$	(1.20	)	$	(0.62	)	$	5.25	$	(0.26	)

Summary of Significant Accounting Policies - Segment and Geographic Information (Details)	12 Months Ended
	Dec. 31, 2018 segment
Accounting Policies [Abstract]
Number of operating segments	1
Number of reporting segments	1

Summary of Significant Accounting Policies - Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Cash and cash equivalents	$ 131,201	$ 166,972	$ 133,930	$ 221,861

Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2018
Minimum
Property and equipment
Estimated useful lives	3 years
Maximum
Property and equipment
Estimated useful lives	10 years

Summary of Significant Accounting Policies - Share-Based Compensation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 30, 2016
Share-Based Compensation
Expected dividend yield	0.00%
Share-based compensation expense	$ 11,072	$ 18,171	$ 31,660
Research and development
Share-Based Compensation
Share-based compensation expense	4,967	11,114	21,380
General and administrative
Share-Based Compensation
Share-based compensation expense	6,105	7,057	$ 10,280
ESPP
Share-Based Compensation
Share-based compensation expense	$ 100	$ 100
ESPP \| Maximum
Share-Based Compensation
Number of shares reserved for issuance under the Plan (in shares)				1,000,000

Summary of Significant Accounting Policies - Schedule of Weighted-Average Assumptions (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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	85.00%	81.00%	71.00%
Risk-free interest rate, minimum	2.39%	1.82%	1.14%
Risk-free interest rate, maximum	2.95%	2.38%	2.37%
Expected term of options (years)	6 years 6 days	6 years 1 month 6 days	6 years 1 month 6 days
Expected dividend yield	0.00%	0.00%	0.00%

Net Loss Per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic and diluted net loss per common share calculation:
Net income (loss)									$ 63,087	$ 114,205	$ (193,420)
Weighted average common shares outstanding - basic (in shares)									37,061	35,919	35,486
Plus: net effect of dilutive stock options and unvested restricted stock units (in shares)									27	88	0
Weighted average common shares outstanding - dilutive (in shares)									37,088	36,007	35,486
Net income (loss) per common share - basic (USD per share)	$ 2.62	$ (0.41)	$ (0.37)	$ (0.36)	$ (0.26)	$ 5.26	$ (0.62)	$ (1.20)	$ 1.70	$ 3.18	$ (5.45)
Net income (loss) per common share - diluted (USD per share)	$ 2.62	$ (0.41)	$ (0.37)	$ (0.36)	$ (0.26)	$ 5.25	$ (0.62)	$ (1.20)	$ 1.70	$ 3.17	$ (5.45)
Anti-dilutive securities
Total (in shares)									6,474	5,361	4,080
Stock options outstanding
Anti-dilutive securities
Total (in shares)									5,873	5,179	3,359
Restricted stock units
Anti-dilutive securities
Total (in shares)									601	182	721

Cash and Cash Equivalents - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Cash and Cash Equivalents [Abstract]
Cash	$ 4.4	$ 9.5
Cash equivalents	$ 126.8	$ 157.4

Cash and Cash Equivalents - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Investments in money market funds \| Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value	$ 97,402	$ 162,457
Investments in money market funds \| Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value	0	0
Investments in money market funds \| Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value	0	$ 0
Investments in corporate debt securities \| Quoted prices in active markets for identical assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value	0
Investments in corporate debt securities \| Significant other observable inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value	29,425
Investments in corporate debt securities \| Significant unobservable inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents, fair value	$ 0

Inception 4 Acquisition (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		1 Months Ended	12 Months Ended
	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			$ 6,900
Transaction costs			$ 1,300
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		$ 11,700
Contingent consideration	$ 105,000	$ 105,000
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		$ 6,100
GA \| Inception 4
Schedule Of Asset Acquisition [Line Items]
Clinical and marketing approval milestones	$ 45,000
Wet AMD \| Inception 4
Schedule Of Asset Acquisition [Line Items]
Clinical and marketing approval milestones	$ 60,000

Licensing and Commercialization Agreement (Details) - USD ($) $ in Thousands	1 Months Ended							3 Months Ended								12 Months Ended			22 Months Ended
	Jun. 30, 2018	Aug. 31, 2017	Jul. 31, 2017	Jun. 30, 2016	Mar. 31, 2015	Sep. 30, 2014	May 31, 2014	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2016
Agreement
Upfront fees received		$ 16,900
Total collaboration revenue								$ 0	$ 0	$ 0	$ 0	$ 0	$ 206,654	$ 1,661	$ 1,662	$ 0	$ 209,977	$ 50,909
License revenue
Agreement
Total collaboration revenue																0	152,912	22,937
Research and development activity revenue
Agreement
Total collaboration revenue																0	56,180	9,741
API transfer revenue
Agreement
Total collaboration revenue																0	754	18,212
Joint operating committee revenue
Agreement
Total collaboration revenue																$ 0	$ 131	$ 19
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
General and administrative \| RHO-adRP License Agreement \| University of Florida Research Foundation (UFRF)
Agreement
Payments for license fees	$ 30

Financing Agreement with Novo Holdings A/S (Details)	1 Months Ended			12 Months Ended			19 Months Ended
Financing Agreement with Novo Holdings A/S (Details)	Nov. 30, 2014 USD ($)	Jan. 31, 2014 USD ($)	May 31, 2013 USD ($) tranche	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Nov. 30, 2014 USD ($)
Agreement
Royalty purchase liability				$ 0	$ 125,000,000
Gain on extinguishment of Royalty Purchase Liability				$ 125,000,000	$ 0	$ 0
Novo A/S \| Novo Agreement \| Fovista, Fovista-Related Products, and Other Products
Agreement
Number of tranches in financing \| tranche			3
Aggregate royalty rights			$ 125,000,000.0
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) - USD ($) $ in Thousands	12 Months Ended
Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property and Equipment
Property and equipment, gross	$ 1,345	$ 1,345
Accumulated depreciation	(1,010)	(827)
Property and equipment, net	335	518
Depreciation expense	$ 183	2,763	$ 757
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	$ 412	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 - Narrative (Details) - USD ($)	12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Tax Cuts and Jobs Act, income tax expense		$ 3,500,000
Income tax benefit	$ 1,100,000
Federal and state tax liability, benefit from income taxes		(4,700,000)
Reduction in deferred tax assets and corresponding valuation allowance	25,000,000
Refund claimed for taxes previously paid	5,000,000
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	5,000,000
Domestic Tax Authority
Operating Loss Carryforwards [Line Items]
Federal net operating loss carryforwards	$ 315,500,000
State and Local Jurisdiction
Operating Loss Carryforwards [Line Items]
Income tax benefit		$ (1,400,000)

Income Taxes - Schedule of Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Percent of pre-tax income:
U.S. federal statutory income tax rate	21.00%	35.00%	35.00%
State taxes, net of federal benefit	18.50%	14.60%	2.80%
Permanent items	4.00%	4.00%	(1.40%)
Remeasurement of deferred tax assets	0.00%	49.90%	0.00%
Impact of state rate changes	(0.20%)	(27.90%)	(11.00%)
Research and development credit	(2.40%)	(0.00%)	1.90%
Alternative minimum tax credit	0.00%	(1.30%)	1.10%
Change in valuation allowance	(42.60%)	(78.60%)	(28.20%)
Effective income tax rate	(1.70%)	(4.30%)	0.20%

Income Taxes - Schedule of Components of Income Tax (Benefit) Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal	$ 0	$ 173	$ (23,393)
State	(1,063)	(1,356)	21
Deferred:
Federal	0	(3,529)	22,966
State	0	0	0
Income tax benefit	$ (1,063)	$ (4,712)	$ (406)

Income Taxes - Schedule of Significant Components of Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets (liabilities)
Deferred revenue	$ 0	$ 40,961
License and technology payments	7,221	8,222
Share-based compensation	20,342	17,599
Accrued expenses	371	608
Depreciation, deferred tax liability	(28)
Depreciation, deferred tax assets		81
Federal and state net operating loss carryforwards	88,766	76,309
Research and development credits	5,933	3,782
Other	5	3,534
Deferred income tax assets	122,610	151,096
Valuation allowance	(122,610)	(147,567)
Net deferred tax assets	$ 0	$ 3,529

Income Taxes - Schedule of Position with Respect to Uncertain Tax Positions (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Opening balance	$ 16,881
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	17
Gross amount of decreases in unrecognized tax benefits during the period - other	(1,413)
Decreases due to settlement with tax authorities during the period	(1,502)
Reduction of unrecognized tax benefits due to expiration of the state of limitations during the period	0
Closing Balance	$ 13,983

Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Future minimum rental commitments under non-cancelable operating leases
2019	$ 1,040
2020	504
Total	1,544
Rent expense	$ 800	$ 3,600	$ 3,000

Commitments and Contingencies (Details) - USD ($) shares in Millions, $ in Millions		1 Months Ended
	Oct. 30, 2018	Oct. 31, 2018	Dec. 31, 2018
Commitments and contingencies
Loss contingency estimate, plaintiff's counsel fees			$ 0.3
License Agreements \| Archemix \| C5 Licensed Product \| Achievement of specified clinical and regulatory milestones \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone			57.5
License Agreements \| Archemix \| C5 Licensed Product \| First indication \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone			30.5
License Agreements \| Archemix \| C5 Licensed Product \| Second and third indication \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone			24.5
License Agreements \| Archemix \| C5 Licensed Product \| Sustained delivery applications \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone			2.5
License Agreements \| Archemix \| C5 Licensed Product \| Achievement of specified commercial milestones \| Maximum
Commitments and contingencies
Amount to be paid on achievement of milestone			22.5
RHO-adRP License Agreement \| University of Florida Research Foundation (UFRF) \| Specified Clinical, Marketing Approval and Reimbursement Approval Milestones Related to a Licensed Product
Commitments and contingencies
Amount to be paid on achievement of milestone			23.5
RHO-adRP License Agreement \| University of Florida Research Foundation (UFRF) \| Specified Commercial Sales Milestones Related to a Licensed Product
Commitments and contingencies
Amount to be paid on achievement of milestone			$ 70.0
Inception 4
Commitments and contingencies
Contingent consideration	$ 105.0	$ 105.0
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%
Inception 4 \| GA
Commitments and contingencies
Clinical and marketing approval milestones	$ 45.0
Inception 4 \| Wet AMD
Commitments and contingencies
Clinical and marketing approval milestones	$ 60.0

Stock Option and Compensation Plans - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		12 Months Ended
	Jan. 01, 2019	Apr. 30, 2016	Aug. 31, 2013	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock Option and Compensation Plans
Options outstanding (in shares)				5,615,000
Weighted-average exercise price of options (in dollars per share)				$ 14.17
Weighted-average remaining contractual life of options				7 years 9 months 18 days
Share-based compensation expense				$ 11,072	$ 18,171	$ 31,660
Shares issued under ESPP (in shares)				16,358
ESPP
Stock Option and Compensation Plans
Number of shares of common stock available for issuance under the Plan (in shares)				952,229
Purchase price of common stock as percentage of fair market value		85.00%
Share-based compensation expense				$ 100	100
Expected weighted average period to recognize share-based compensation costs				3 months 18 days
Common stock issued (in shares)				31,413
Proceeds from stock plans				$ 65
Restricted stock units
Stock Option and Compensation Plans
Share-based compensation expense				$ 300
RSUs expected to vest (in shares)				550,000
Weighted-average fair value of RSUs expected to vest (in dollars per share)				$ 10.36
Aggregate intrinsic value of RSUs expected to vest				$ 700
Total fair value vested				3,400
Employees \| Stock options
Stock Option and Compensation Plans
Share-based compensation expense				7,600	13,100	22,800
Unrecognized share-based compensation costs for option awards, net of estimated forfeitures				$ 9,000
Expected weighted average period to recognize share-based compensation costs				2 years 1 month 6 days
Employees \| Restricted stock units
Stock Option and Compensation Plans
Share-based compensation expense				$ 3,300	4,400	6,900
Expected weighted average period to recognize share-based compensation costs				1 year 9 months 18 days
Unrecognized compensation costs, net of estimated forfeitures				$ 3,200
Consultants \| Non-employee Options
Stock Option and Compensation Plans
Share-based compensation expense				200	$ 300	$ 1,700
Unrecognized share-based compensation costs for option awards, net of estimated forfeitures				$ 200
Expected weighted average period to recognize share-based compensation costs				1 year 8 months 12 days
Consultants \| Restricted stock units
Stock Option and Compensation Plans
Expected weighted average period to recognize share-based compensation costs				1 year
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)				840,000
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)				8,554,000
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)	1,656,000
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

Stock Option and Compensation Plans - Summary of Stock Option Activity (Details) - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common Stock Options
Outstanding at beginning of year (in shares)	5,284	3,359	3,009
Granted (in shares)	1,293	3,024	972
Exercised (in shares)	0	(20)	(428)
Expired or forfeited (in shares)	(674)	(1,079)	(194)
Outstanding at end of year (in shares)	5,903	5,284	3,359
Weighted Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 19.58	$ 39.92	$ 30.43
Granted (in dollars per share)	1.67	3.50	60.40
Exercised (in dollars per share)	0.00	1.64	15.73
Expired or forfeited (in dollars per share)	36.54	38.17	48.63
Outstanding at end of year (in dollars per share)	$ 13.72	$ 19.58	$ 39.92
Options exercisable at end of year (in shares)	2,709	1,954	1,531
Weighted average grant date fair value (per share) of options granted during the period (in dollars per share)	$ 1.20	$ 2.45	$ 38.18

Stock Option 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, 2018 USD ($) $ / shares shares
Options Outstanding
Total Options Outstanding (in shares) \| shares	5,903
Weighted Average Remaining Life (Years)	7 years 10 months 24 days
Weighted Average Exercise Price (in dollars per share)	$ 13.72
Aggregate Intrinsic Value of Options Outstanding \| $	$ 3
Options Exercisable
Number Exercisable (in shares) \| shares	2,709
Weighted Average Exercise Price (in dollars per share)	$ 24.07
Aggregate Intrinsic Value of Options Exercisable \| $	$ 3
$0.12-$10.03
Options Outstanding
Total Options Outstanding (in shares) \| shares	4,231
Weighted Average Remaining Life (Years)	8 years 9 months 18 days
Weighted Average Exercise Price (in dollars per share)	$ 3.07
Options Exercisable
Number Exercisable (in shares) \| shares	1,174
Weighted Average Exercise Price (in dollars per share)	$ 4.20
Exercise prices, low end of range (in dollars per share)	0.12
Exercise prices, high end of range (in dollars per share)	$ 10.03
$10.04-$20.00
Options Outstanding
Total Options Outstanding (in shares) \| shares	133
Weighted Average Remaining Life (Years)	4 years 6 months
Weighted Average Exercise Price (in dollars per share)	$ 13.68
Options Exercisable
Number Exercisable (in shares) \| shares	133
Weighted Average Exercise Price (in dollars per share)	$ 13.68
Exercise prices, low end of range (in dollars per share)	10.04
Exercise prices, high end of range (in dollars per share)	$ 20.00
$20.01-$30.00
Options Outstanding
Total Options Outstanding (in shares) \| shares	114
Weighted Average Remaining Life (Years)	4 years 4 months 24 days
Weighted Average Exercise Price (in dollars per share)	$ 24.69
Options Exercisable
Number Exercisable (in shares) \| shares	114
Weighted Average Exercise Price (in dollars per share)	$ 24.69
Exercise prices, low end of range (in dollars per share)	20.01
Exercise prices, high end of range (in dollars per share)	$ 30.00
$30.01-$40.00
Options Outstanding
Total Options Outstanding (in shares) \| shares	680
Weighted Average Remaining Life (Years)	4 years 4 months 24 days
Weighted Average Exercise Price (in dollars per share)	$ 33.12
Options Exercisable
Number Exercisable (in shares) \| shares	680
Weighted Average Exercise Price (in dollars per share)	$ 33.12
Exercise prices, low end of range (in dollars per share)	30.01
Exercise prices, high end of range (in dollars per share)	$ 40.00
$40.01-$55.00
Options Outstanding
Total Options Outstanding (in shares) \| shares	508
Weighted Average Remaining Life (Years)	6 years 7 months 6 days
Weighted Average Exercise Price (in dollars per share)	$ 46.61
Options Exercisable
Number Exercisable (in shares) \| shares	420
Weighted Average Exercise Price (in dollars per share)	$ 46.48
Exercise prices, low end of range (in dollars per share)	40.01
Exercise prices, high end of range (in dollars per share)	$ 55.00
$55.01-$73.22
Options Outstanding
Total Options Outstanding (in shares) \| shares	237
Weighted Average Remaining Life (Years)	7 years
Weighted Average Exercise Price (in dollars per share)	$ 72.32
Options Exercisable
Number Exercisable (in shares) \| shares	188
Weighted Average Exercise Price (in dollars per share)	$ 72.09
Exercise prices, low end of range (in dollars per share)	55.01
Exercise prices, high end of range (in dollars per share)	$ 73.22

Stock Option 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, 2018	Dec. 31, 2017	Dec. 31, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Cash proceeds from options exercised	$ 0	$ 33	$ 6,934
Aggregate intrinsic value of options exercised	$ 0	$ 43	$ 14,439

Stock Option and Compensation Plans - Summary of Outstanding RSU Awards Granted (Details) - Restricted stock units shares in Thousands	12 Months Ended
	Dec. 31, 2018 $ / shares shares
Restricted Stock Units
Outstanding, beginning of period (in shares) \| shares	327
Awarded (in shares) \| shares	499
Vested (in shares) \| shares	(80)
Forfeited (in shares) \| shares	(67)
Outstanding, end of period (in shares) \| shares	679
Weighted Average Grant-Date Fair Value
Outstanding, beginning of period (in dollars per share) \| $ / shares	$ 51.08
Awarded (in dollars per share) \| $ / shares	1.45
Vested (in dollars per share) \| $ / shares	46.25
Forfeited (in dollars per share) \| $ / shares	45.57
Outstanding, end of period (in dollars per share) \| $ / shares	$ 15.61

Employee Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
Employee Benefit Plan (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Defined contribution plan, cost recognized	$ 0.2	$ 0.7	$ 0.8

Restructuring Activities (Details)	Jan. 31, 2017
Severance and other employee costs
Restructuring Cost and Reserve [Line Items]
Percent of personnel expected to be effected by reduction in workforce	80.00%

Restructuring Activities - Reconciliation of severance-related accrual activity (Details) - Severance and other employee costs $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Restructuring Reserve [Roll Forward]
Beginning Balance	$ 2,529
Accrued restructuring expenses	0
Payments	(2,529)
Ending Balance	$ 0

Selected Quarterly Financial Information (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Collaboration revenue	$ 0	$ 0	$ 0	$ 0	$ 0	$ 206,654	$ 1,661	$ 1,662	$ 0	$ 209,977	$ 50,909
Research and development expenses	16,128	9,407	8,516	7,686	7,946	10,707	15,657	31,979	41,737	66,289	196,295
General and administrative expenses	5,667	5,968	6,332	5,645	6,913	7,059	8,552	13,159	23,612	35,683	50,178
Income (loss) from operations	(21,795)	(15,375)	(14,848)	(13,331)	(14,859)	188,888	(22,548)	(43,476)	$ (65,349)	$ 108,005	$ (195,564)
Net income (loss) attributable to common stockholders	$ 104,114	$ (14,745)	$ (13,209)	$ (13,073)	$ (9,542)	$ 189,073	$ (22,204)	$ (43,122)
Basic (in dollars per share)	$ 2.62	$ (0.41)	$ (0.37)	$ (0.36)	$ (0.26)	$ 5.26	$ (0.62)	$ (1.20)	$ 1.70	$ 3.18	$ (5.45)
Dilutive (in dollars per share)	$ 2.62	$ (0.41)	$ (0.37)	$ (0.36)	$ (0.26)	$ 5.25	$ (0.62)	$ (1.20)	$ 1.70	$ 3.17	$ (5.45)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1337-109256

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=109256448&loc=d3e4984-109258

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(21))
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1252-109256

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(23))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109260490&loc=SL5780133-109256

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI http://asc.fasb.org/extlink&oid=109256448&loc=d3e4984-109258

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1252-109256

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(23))
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22694-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109260490&loc=d3e1337-109256

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(21))
-URI http://asc.fasb.org/extlink&oid=115205541&loc=SL114868664-224227

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 60B
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109260490&loc=SL5780133-109256

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(19))
-URI http://asc.fasb.org/extlink&oid=114873790&loc=SL114874131-224263

+ Details