Tesaro (TSRO) 10-K 28 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 22, 2018	Jun. 30, 2017
Document and Entity Information
Entity Registrant Name	TESARO, Inc.
Entity Central Index Key	1,491,576
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 5,213,481,640
Entity Common Stock, Shares Outstanding		54,563,915
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 643,095	$ 785,877
Accounts receivable	53,416	6,195
Inventories	57,939	14,700
Other current assets	33,511	10,515
Total current assets	787,961	817,287
Intangible assets, net	56,384	12,877
Property and equipment, net	9,652	6,640
Restricted cash	2,552	1,694
Other assets	5,636	3,795
Total assets	862,185	842,293
Current liabilities:
Accounts payable	4,172	5,236
Accrued expenses	154,808	68,700
Deferred revenue, current	324	95
Other current liabilities	6,902	2,978
Total current liabilities	166,206	77,009
Convertible notes, net	143,446	131,775
Long-term debt, net	293,659
Deferred revenue, non-current	211	305
Other non-current liabilities	9,577	5,086
Total liabilities	613,099	214,175
Commitments and contingencies (Notes 12 and 14)
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized at both December 31, 2016 and December 31, 2017; no shares issued or outstanding at both December 31, 2016 and December 31, 2017
Common stock, $0.0001 par value; 100,000,000 shares authorized at both December 31, 2016 and December 31, 2017; 53,621,679 and 54,464,039 shares issued and outstanding at December 31, 2016 and December 31, 2017, respectively	5	5
Additional paid-in capital	1,724,850	1,604,798
Accumulated other comprehensive loss	(5,882)	(2,924)
Accumulated deficit	(1,469,887)	(973,761)
Total stockholders' equity	249,086	628,118
Total liabilities and stockholders' equity	$ 862,185	$ 842,293

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Consolidated Balance Sheets
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	54,464,039	53,621,679
Common stock, shares outstanding	54,464,039	53,621,679

Consolidated Statements of Oper

Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Revenue	$ 223,326	$ 58,018	$ 4,038
Expenses:
Cost of sales - product	41,137	1,203	62
Cost of sales - intangible asset amortization	6,158	1,855	268
Research and development	308,742	235,144	155,390
Selling, general and administrative	336,808	158,578	78,701
Acquired in-process research and development	10,000	18,940	2,000
Total expenses	702,845	415,720	236,421
Loss from operations	(479,519)	(357,702)	(232,383)
Interest expense	(19,758)	(16,487)	(15,414)
Interest income	4,147	1,440	48
Other income	328
Loss before income taxes	(494,802)	(372,749)	(247,749)
Provision for income taxes	1,324	1,475
Net loss	$ (496,126)	$ (374,224)	$ (247,749)
Net loss per share applicable to common stockholders - basic and diluted (in dollars per share)	$ (9.17)	$ (7.85)	$ (6.29)
Weighted-average number of common shares used in net loss per share applicable to common stockholders - basic and diluted (in shares)	54,080	47,652	39,387
Comprehensive loss:
Net loss	$ (496,126)	$ (374,224)	$ (247,749)
Other comprehensive income (loss):
Unrealized gain/(loss) on pension obligation	(3,359)	(2,782)
Foreign currency translation adjustments	401	(142)
Other comprehensive income/(loss)	(2,958)	(2,924)
Comprehensive loss	(499,084)	(377,148)	(247,749)
Product revenue
Revenues:
Revenue	120,700	5,174	2,026
Licenses, collaboration and other revenues
Revenues:
Revenue	$ 102,626	$ 52,844	$ 2,012

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	AOCI Attributable to Parent [Member]	Accumulated Deficit	Total
Balance at Dec. 31, 2014	$ 4	$ 474,562		$ (350,510)	$ 124,056
Balance (in shares) at Dec. 31, 2014	36,110,082
Increase (Decrease) in Stockholders' Equity
Issuance of common stock, net of issuance costs		179,753			179,753
Issuance of common stock, net of issuance costs (in shares)	3,755,000
Issuance of common stock resulting from exercise of stock options		7,930			7,930
Issuance of common stock resulting from exercise of stock options (in shares)	382,580
Issuance of common stock resulting from Employee Stock Purchase Plan		830			830
Issuance of common stock resulting from Employee Stock Purchase Plan (in shares)	20,601
Issuance of common stock resulting from the vesting of restricted stock units, net of shares withheld for taxes		201			201
Issuance of common stock resulting from the vesting of restricted stock units, net of shares withheld for taxes (in shares)	8,091
Issuance of common stock as payment of Board of Directors fees in lieu of cash		266			266
Issuance of common stock as payment of Board of Directors fees in lieu of cash (in shares)	3,429
Stock-based compensation expense		25,648			25,648
Net loss				(247,749)	(247,749)
Balance at Dec. 31, 2015	$ 4	688,788		(598,259)	90,533
Balance (in shares) at Dec. 31, 2015	40,279,783
Increase (Decrease) in Stockholders' Equity
Retroactive adjustment to beginning accumulated deficit and additional paid-in capital resulting from adoption of ASUs | ASU No. 2016-09		1,278		(1,278)
Issuance of common stock, net of issuance costs	$ 1	838,090			838,091
Issuance of common stock, net of issuance costs (in shares)	12,632,356
Issuance of common stock resulting from exercise of stock options		25,958			25,958
Issuance of common stock resulting from exercise of stock options (in shares)	643,035
Issuance of common stock resulting from Employee Stock Purchase Plan		2,229			2,229
Issuance of common stock resulting from Employee Stock Purchase Plan (in shares)	42,478
Issuance of common stock resulting from the vesting of restricted stock units, net of shares withheld for taxes (in shares)	18,000
Issuance of common stock as payment of Board of Directors fees in lieu of cash		345			345
Issuance of common stock as payment of Board of Directors fees in lieu of cash (in shares)	6,027
Stock-based compensation expense		48,110			48,110
Other comprehensive income/(loss)			$ (2,924)		(2,924)
Net loss				(374,224)	(374,224)
Balance at Dec. 31, 2016	$ 5	1,604,798	(2,924)	(973,761)	$ 628,118
Balance (in shares) at Dec. 31, 2016	53,621,679				53,621,679
Increase (Decrease) in Stockholders' Equity
Issuance of common stock resulting from exercise of stock options		25,883			$ 25,883
Issuance of common stock resulting from exercise of stock options (in shares)	597,209
Issuance of common stock resulting from Employee Stock Purchase Plan		3,743			3,743
Issuance of common stock resulting from Employee Stock Purchase Plan (in shares)	42,386
Issuance of common stock resulting from the vesting of restricted stock units, net of shares withheld for taxes (in shares)	199,654
Issuance of common stock as payment of Board of Directors fees in lieu of cash		464			464
Issuance of common stock as payment of Board of Directors fees in lieu of cash (in shares)	3,111
Stock-based compensation expense		89,962			89,962
Other comprehensive income/(loss)			(2,958)		(2,958)
Net loss				(496,126)	(496,126)
Balance at Dec. 31, 2017	$ 5	$ 1,724,850	$ (5,882)	$ (1,469,887)	$ 249,086
Balance (in shares) at Dec. 31, 2017	54,464,039				54,464,039

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' (Deficit) Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Issuance of stock, offering costs	$ 36,305
Common Stock
Issuance of stock, offering costs		$ 11,752

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net loss	$ (496,126)	$ (374,224)	$ (247,749)
Adjustments to reconcile net loss to net cash used in operating activities:
Acquired in-process research and development	10,000	18,940	2,000
Depreciation and amortization expense	9,530	3,113	1,037
Stock-based compensation expense	90,426	48,455	25,914
Non-cash interest expense	11,734	10,450	9,360
Write-down of inventory to net realizable value	16,730
Changes in operating assets and liabilities:
Accounts receivable	(47,134)	(3,634)	(2,562)
Inventories	(59,968)	(13,594)	(1,106)
Other assets	(20,214)	(7,770)	(3,639)
Accounts payable	(1,036)	(2,835)	1,924
Accrued expenses	80,837	31,896	20,077
Deferred revenues	134	309	92
Other liabilities	4,966	1,223	121
Net cash used in operating activities	(400,121)	(287,671)	(194,531)
Investing Activities
Acquisition of product candidates, technology licenses and milestone payments	(59,665)	(18,940)	(17,000)
Purchase of property and equipment	(5,978)	(2,895)	(2,305)
Change in restricted cash	(870)	(1,489)	(500)
Net cash used in investing activities, Total	(66,513)	(23,324)	(19,805)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Proceeds from sales of common stock, net of issuance costs	(8)	838,099	179,753
Proceeds from term loan, net of issuance costs	293,596
Proceeds from exercise of stock options and Employee Stock Purchase Plan	29,719	28,785	7,868
Net cash provided by financing activities	323,307	866,884	187,621
Effect of exchange rate changes on cash and cash equivalents	545	(158)
Increase (decrease) in cash and cash equivalents	(142,782)	555,731	(26,715)
Cash and cash equivalents at beginning of period	785,877	230,146	256,861
Cash and cash equivalents at end of period	643,095	785,877	230,146
Non-cash investing and financing activities
Stock option exercise proceeds receivable as of period end		93	691
Leasehold improvement assets funded by lessor	585	2,230
Purchase of property and equipment - cash not paid as of period end	40	230	238
Supplemental cash flow information
Cash paid for interest	6,038	6,038	6,071
Income Taxes Paid	$ 573	$ 1,430	$ 1

Nature of Business

Nature of Business	12 Months Ended
	Dec. 31, 2017
Description of Business
Nature of Business	TESARO, Inc. Notes to Consolidated Financial Statement 1. Nature of Business The Company TESARO, Inc., or the Company or TESARO, was incorporated in Delaware and commenced operations in 2010. Headquartered in Waltham, Massachusetts, TESARO is a commercial-stage biopharmaceutical company devoted to providing transformative therapies to people bravely facing cancer. The Company’s primary focus is to develop treatments for solid tumors using various approaches, including small molecules and immuno-oncology antibodies, as monotherapies or in combinations. The Company has in-licensed and is developing several oncology-related product candidates, and has entered into several research collaborations with third parties for the discovery of new candidates. The Company operates in one segment. The Company is subject to a number of risks, including dependence on key individuals, regulatory and manufacturing risks, the need to develop additional commercially viable products, risks associated with competitors, many of which are larger and better capitalized, risks related to intellectual property, and the need to obtain adequate additional financing to fund the development and potential commercialization of its product candidates and further its in-licensing and acquisition activities. The Company’s two currently marketed products, ZEJULA® and VARUBI®/VARUBY®, are approved in both the U.S. and the European Union, or EU. ZEJULA is approved as a maintenance treatment of adults with recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer who are in a complete or partial response to platinum-based chemotherapy. VARUBI/VARUBY is approved for use in combination with other antiemetic agents in adults for the prevention of delayed nausea and vomiting associated with initial and repeat courses of emetogenic cancer chemotherapy, including, but not limited to, highly emetogenic chemotherapy. As further described in Note 17, “ Subsequent Events ”, the Company has determined that it will cease marketing and distribution of the intravenous, or IV, formulation of VARUBI and intends to pursue strategic alternatives for the VARUBI brand. Liquidity The Company has incurred significant operating losses since inception and has relied on its ability to fund its operations through private and public equity and debt financings, and to a lesser extent through product sales and license and collaboration arrangements. Management expects operating losses and negative operating cash flows to continue for the foreseeable future. As the Company continues to incur losses, the transition to profitability is dependent upon the successful development, approval, and commercialization of its products and product candidates and the achievement of a level of revenues adequate to support its cost structure. The Company believes that its currently available funds in addition to cash generated from sales of its products will be sufficient to fund the Company’s operations through at least the next 12 months from the issuance of this Annual Report on Form 10-K. Management’s belief with respect to its ability to fund operations is based on estimates that are subject to risks and uncertainties. If actual results are different from management’s estimates, the Company may need to seek additional funding.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Basis of Presentation and Significant Accounting Policies
Basis of Presentation and Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The Company’s consolidated financial statements reflect the operations of the Company and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States, or GAAP. See “ New Accounting Pronouncements - Recently Adopted ” below for a discussion of certain revisions to prior period financial statements made in connection with the Company’s adoption of new revenue recognition guidance retroactive to January 1, 2015. Segment 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 segment, which is the business of developing and commercializing safer and more effective oncology-focused therapeutics. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, other comprehensive loss and the related disclosures. Significant estimates in these consolidated financial statements include estimates made in connection with accrued research and development expenses, stock-based compensation expense, revenue, valuation of convertible notes, inventory, intangible assets and related amortization. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions. Concentrations of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash and cash equivalents. The Company maintains its cash and cash equivalent balances primarily in the form of money market fund accounts with financial institutions that management believes are creditworthy. The Company’s investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. The Company has no financial instruments with off-balance-sheet risk of loss. The Company also is subject to credit risk from its accounts receivable related to its product sales, collaborators and licenses. As part of its credit management policy, the Company performs ongoing credit evaluations of its customers, and the Company has not required collateral from any customer. The Company has not recorded any allowances for doubtful accounts at either December 31, 2016 or 2017. Foreign Currency A subsidiary’s functional currency is the currency of the primary economic environment in which the subsidiary operates; normally, that is the currency of the environment in which a subsidiary primarily generates and expends cash. In making the determination of the appropriate functional currency for a subsidiary, the Company considers cash flow indicators, local market indicators, financing indicators and the subsidiary’s relationship with both the parent company and other subsidiaries. For subsidiaries that are primarily a direct and integral component or extension of the parent entity’s operations, the U.S. dollar is the functional currency. For each foreign subsidiary with a functional currency other than the U.S. dollar, assets and liabilities are translated at current exchange rates at the balance sheet date. Revenue and expense items are translated at average foreign exchange rates for the period. Adjustments resulting from the translation of the financial statements of these subsidiaries into U.S. dollars are excluded from the determination of net loss and are recorded in accumulated other comprehensive loss, a separate component of stockholders’ equity. For foreign subsidiaries with the U.S. dollar as the functional currency, monetary assets and liabilities are re-measured into U.S. dollars at the current exchange rate on the balance sheet date. Nonmonetary assets and liabilities are re-measured into U.S. dollars at historical exchange rates. Revenue and expense items are translated at average exchange rates prevailing during each period. Consolidated realized and unrealized foreign currency transaction gains and losses are recorded in selling, general and administrative expenses in the consolidated statements of operations and comprehensive loss. Consolidated realized and unrealized foreign currency transaction losses were negligible for the year ended December 31, 2015, and were $0.2 million and $0.5 million for the years ended December 31, 2016 and 2017, respectively. Revenue Recognition Effective January 1, 2017, the Company adopted Accounting Standards Codification, or ASC, Topic 606, Revenue from Contracts with Customers , using the full retrospective transition method. Under this method, the Company has revised its consolidated financial statements for the years ended December 31, 2015 and 2016, and applicable interim periods within those years, as if Topic 606 had been effective for those periods. This standard applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. Under Topic 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. For a complete discussion of accounting for net product revenue and license, collaboration and other revenues, see Note 13, “ Revenue Recognition ”. Cash and Cash Equivalents The Company considers all highly-liquid investments with original or remaining maturity from the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents include bank demand deposits and money market funds that invest primarily in certificates of deposit, commercial paper and U.S. government and U.S. government agency obligations. Cash equivalents are reported at fair value. Restricted Cash Restricted cash consists of cash balances held as collateral for the Company’s employee credit card programs. Fair Value of Financial Instruments The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The fair value hierarchy prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of investment credit quality. The hierarchy defines three levels of valuation inputs: Level 1 inputs Quoted prices in active markets for identical assets or liabilities Level 2 inputs Observable inputs other than Level 1 inputs, including quoted prices in active markets for similar assets or liabilities and quoted prices for identical assets or liabilities in markets that are not active Level 3 inputs Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability The following table presents information about the Company’s financial assets and liabilities that have been measured at fair value at December 31, 2016 and 2017 and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands): December 31, 2016 Description Balance Sheet Classification Total Level 1 Level 2 Level 3 Assets: Money market funds Cash and cash equivalents $ 766,186 $ 766,186 $ — $ — Total assets $ 766,186 $ 766,186 $ — $ — December 31, 2017 Description Balance Sheet Classification Total Level 1 Level 2 Level 3 Assets: Money market funds Cash and cash equivalents $ 593,955 $ 593,955 $ — $ — Total assets $ 593,955 $ 593,955 $ — $ — The carrying amounts of accounts payable and accrued expenses approximate their fair values due to their short-term maturities. In September 2014, the Company issued $201.3 million aggregate principal amount of 3.00% convertible senior notes due October 1, 2021, or the Convertible Notes. Interest is payable semi-annually in arrears on April 1 and October 1 of each year, beginning on April 1, 2015. As of December 31, 2017, the carrying value of the Convertible Notes was $143.4 million, net of unamortized discount and debt issuance costs and the fair value of the principal amount was $499.1 million. As of December 31, 2017, the carrying value of the Company’s borrowing under its term loan agreement approximated its fair value, considering the short period of time since the December 6, 2017 borrowing date. The Convertible Notes and the term loan agreement are discussed in more detail in Note 7, “ Debt. ” Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Property and equipment are depreciated using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized over the economic life of the asset or the remaining lease term, whichever is shorter. Maintenance and repairs are expensed as incurred. The following estimated useful lives were used to depreciate the Company’s assets: Estimated Useful Life Furniture and fixtures years Computer equipment and software years Manufacturing equipment years Leasehold improvements Shorter of the useful life or the remaining lease term Upon retirement or sale, the cost of the disposed asset and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized in income. The Company reviews long-lived assets when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparison of an asset’s book value to the estimated undiscounted future net cash flows that the asset is expected to generate. If the estimated future undiscounted net cash flows are less than the book value, the asset is considered to be impaired, and the impairment loss to be recognized in income is measured as the amount by which the book value of the asset exceeds its fair value, which is measured based on the estimated discounted future net cash flows that the asset is expected to generate. Research and Development Expenses Research and development costs are charged to expense as incurred and include: · employee-related expenses, including salaries, bonuses, benefits, travel and stock-based compensation expense; · fees and expenses incurred under agreements with contract research organizations, investigative sites, research consortia and other entities in connection with the conduct of clinical trials and preclinical studies and related services, such as administrative, data management, laboratory and biostatistics services; · the cost of acquiring, developing and manufacturing active pharmaceutical ingredients for product candidates that have not received regulatory approval, clinical trial materials and other research and development materials; · fees and costs related to regulatory filings and activities; · pre-commercial license fees and milestone payments related to the acquisition of in-licensed product candidates, which are reported on the statements of operations as acquired in-process research and development; · facilities, depreciation and other expenses, which include direct and allocated expenses for rent, utilities, maintenance of facilities, insurance and other supplies; and · other costs associated with clinical, preclinical, discovery and other research activities. Costs for certain development activities, such as clinical trials and manufacturing development activities, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, and information provided to the Company by its vendors on their actual costs incurred or level of effort expended. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected on the consolidated balance sheets as prepaid or accrued research and development expenses. Certain clinical development costs incurred by the Company with respect to its niraparib program are reimbursed as part of a collaborative research agreement with Merck Sharp & Dohme B.V., a subsidiary of Merck & Co., Inc., or Merck. Cost-sharing amounts received by the Company are recorded as a reduction to research and development expenses. Acquired In-Process Research and Development Expense The Company has acquired the rights to develop and commercialize new product candidates. Up-front payments that relate to the acquisition of a new drug compound, as well as pre-commercial milestone payments, are immediately expensed as acquired in-process research and development in the period in which they are incurred, provided that the new drug compound did not also include processes or activities that would constitute a “business” as defined under GAAP, the drug has not achieved regulatory approval for marketing and, absent obtaining such approval, has no established alternative future use. Milestone payments made to third parties subsequent to regulatory approval are capitalized as intangible assets and amortized over the estimated remaining useful life of the related product. Royalties owed on sales of the products licensed pursuant to the agreements are expensed in the period the related revenues are recognized. Advertising Expenses The costs of advertising are expensed as incurred and included in selling, general, and administrative expenses in the consolidated statements of operations and comprehensive loss. For the years ended December 31, 2015, 2016 and 2017, advertising expenses totaled $3.6 million, $9.2 million, and $21.1 million, respectively. Comprehensive Loss Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Comprehensive loss consists of net loss and other comprehensive loss. Other comprehensive loss includes foreign currency translation adjustments and unrealized gains and losses on pension obligations. The following table presents changes in the components of accumulated other comprehensive loss (in thousands): Foreign currency translation adjustments Unrealized loss on pension liability Total Balance at December 31, 2015 $ — $ — $ — Other comprehensive (loss) income (142) (2,782) (2,924) Balance at December 31, 2016 (142) (2,782) (2,924) Other comprehensive (loss) income 401 (3,359) (2,958) Balance at December 31, 2017 $ 259 $ (6,141) $ (5,882) Income Taxes The Company accounts for income taxes in accordance with ASC Topic 740, Accounting for Income Taxes , which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. The Company determines its deferred tax assets and liabilities based on differences between financial reporting and tax bases of assets and liabilities, which are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. On December 22, 2017, the Tax Cuts and Jobs Act of 2017 was signed into law, resulting in significant changes to the U.S. corporate income tax system. For additional details regarding this act, see Note 10, “ Income Taxes ”. Stock-Based Compensation Expense Stock-based compensation is recognized as expense for each stock-based award based on its estimated fair value. The Company determines the fair value of each stock option award at its grant date using the Black-Scholes option pricing model. The Company determines the fair value of each restricted stock unit, or RSU, at its grant date based on the closing market price of the Company’s common stock on that date. The value of the award is recognized as expense on a straight-line basis over the requisite service period and is adjusted for pre-vesting forfeitures in the period in which the forfeitures occur. For stock awards that have a performance condition, the Company recognizes compensation expense based on its assessment of the probability that the performance condition will be achieved, using an accelerated attribution model, over the explicit or implicit service period. Inventory Inventories are stated at the lower of cost or estimated net realizable value, on a first-in, first-out, or FIFO, basis. Prior to the regulatory approval of its product candidates, the Company incurs expenses for the manufacture of drug product that could potentially be available to support the commercial launch of its products. Until the first reporting period when regulatory approval has been received or is otherwise considered probable, the Company records all such costs as research and development expense. Inventory used in clinical trials is also expensed as research and development expense, when selected for such use. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and writes down any excess and obsolete inventory to its net realizable value in the period in which the impairment is first identified. Such impairment charges, should they occur, are recorded as a component of cost of product sales in the consolidated statements of operations and comprehensive loss. The determination of whether inventory costs will be realizable requires the use of estimates by management. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required. Intangible Assets The Company maintains definite-lived intangible assets related to milestone payments made to third parties subsequent to regulatory approval for acquired and in-licensed product candidates. These assets are amortized over their remaining useful lives, which are generally estimated to be the remaining patent life. If the Company’s estimate of the product’s useful life is shorter than the remaining patent life, then the shorter period is used. Intangible assets are amortized using the economic consumption method if anticipated future revenues can be reasonably estimated. The straight-line method is used when future revenues cannot be reasonably estimated, with a cumulative catch-up of amortization expense for milestone payments that do not result in additional intellectual property rights and/or incremental cash flows. Amortization expense is recorded as a component of cost of sales in the consolidated statements of operations and comprehensive loss. The Company assesses its intangible assets for impairment if indicators are present or changes in circumstance suggest that impairment may exist. Events that could result in an impairment, or trigger an interim impairment assessment, include the receipt of additional clinical or nonclinical data regarding one of the Company’s drug candidates or a potentially competitive drug candidate, changes in the clinical development program for a drug candidate, or new information regarding potential sales for the drug. If impairment indicators are present or changes in circumstance suggest that impairment may exist, the Company performs a recoverability test by comparing the sum of the estimated undiscounted cash flows of each intangible asset to its carrying value on the consolidated balance sheet. If the undiscounted cash flows used in the recoverability test are less than the carrying value, the Company would determine the fair value of the intangible asset and recognize an impairment loss if the carrying value of the intangible asset exceeds its fair value. Net Loss Per Share Basic and diluted net loss per common share is calculated by dividing net loss applicable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration of common stock equivalents. The Company’s potentially dilutive shares, which include outstanding stock options, Employee Stock Purchase Plan awards, unvested RSUs, and shares issuable upon conversion of the Convertible Notes, are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. The following table presents amounts that were excluded from the calculation of diluted net loss per share, due to their anti-dilutive effect (in thousands): Years Ended December 31, 2015 2016 2017 Outstanding stock options 5,878 6,979 6,908 Unvested restricted stock units 60 760 1,159 Shares issuable upon conversion of Convertible Notes 492 3,765 2,695 6,430 11,504 10,762 In September 2014, the Company issued Convertible Notes, which provide in certain situations for the conversion of the outstanding principal amount of the Convertible Notes into shares of the Company’s common stock at a predefined conversion rate. See Note 7, “ Debt ”, for additional information. In conjunction with the issuance of the Convertible Notes, the Company entered into capped call option transactions, or Capped Calls, with certain counterparties. The Capped Calls are expected generally to reduce the potential dilution, and/or offset, to an extent, the cash payments the Company may choose to make in excess of the principal amount, upon conversion of the Convertible Notes. As provided by the terms of the indenture underlying the Convertible Notes, the Company has a choice to settle the conversion obligation for the Convertible Notes in cash, shares or any combination of the two. The Company currently intends to settle the par value of the Convertible Notes in cash and any excess conversion premium in shares. Accordingly, the par value of the Convertible Notes will not be included in the calculation of diluted income per share, but the dilutive effect of the conversion premium will be considered in the calculation of diluted net income per share using the treasury stock method. The Convertible Notes were convertible as of December 31, 2015, 2016 and 2017. The share figures in the table above represent the estimated incremental shares that would be issued, after the consideration of the Capped Calls, assuming conversion of all of the outstanding Convertible Notes as of the respective balance sheet date. New Accounting Pronouncements - Recently Adopted In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2014-09, which amends the guidance for accounting for revenue from contracts with customers. This ASU supersedes the revenue recognition requirements in ASC Topic 605, Revenue Recognition , and creates a new Topic 606, Revenue from Contracts with Customers . In 2015 and 2016, the FASB issued additional ASUs related to Topic 606 that delayed the effective date of the guidance and clarified various aspects of the new revenue guidance, including principal versus agent considerations, identifying performance obligations, and licensing, and they include other improvements and practical expedients. The Company adopted this new standard on January 1, 2017 using the full retrospective transition method, and has elected to use the following practical expedients that are permitted under the rules of the adoption, which have been applied consistently to all contracts within all reporting periods presented: · For completed contracts that had variable consideration, the Company has used the transaction price at the date the contract was completed rather than estimating variable consideration amounts in the comparative reporting periods. Therefore, the Company did not need to estimate its discounts, returns, chargebacks, rebates, co-pay assistance and other allowances on product sales made in the comparative reporting periods. · For all reporting periods presented before January 1, 2017, the Company has not disclosed the amount of the transaction price allocated to the remaining performance obligations or an explanation of when the Company expects to recognize that amount as revenue. Impact of Adoption The Company, as a result of adopting Topic 606 on January 1, 2017, has revised its comparative financial statements for the prior years as if Topic 606 had been effective for those periods. As a result, the following financial statement line items for the years ended December 31, 2015 and 2016 were affected. Consolidated Statements of Operations and Comprehensive Loss Year Ended December 31, 2015 As revised As originally Effect of change Product revenue, net $ 2,026 $ - $ 2,026 License, collaboration and other revenues 2,012 317 1,695 Cost of sales – product 62 - 62 Loss from operations (232,383) (236,042) 3,659 Net loss (247,749) (251,408) 3,659 Net loss per share applicable to common stockholders - basic and diluted $ (6.29) $ (6.38) $ 0.09 Year Ended December 31, 2016 As revised As originally Effect of change Product revenue, net $ 5,174 $ 6,877 $ (1,703) License, collaboration and other revenues 52,844 37,946 14,898 Cost of sales – product 1,203 1,256 (53) Loss from operations (357,702) (370,950) 13,248 Net loss (374,224) (387,472) 13,248 Net loss per share applicable to common stockholders - basic and diluted $ (7.85) $ (8.13) $ 0.28 Consolidated Balance Sheets December 31, 2016 (in thousands) As revised As originally Effect of change Accounts receivable $ 6,195 $ 5,343 $ 852 Other current assets 10,515 8,919 1,596 Accrued expenses 68,700 68,271 429 Deferred revenue, current 95 288 (193) Deferred revenue, non-current 305 — 305 Customer deposit — 15,000 (15,000) Accumulated deficit $ (973,761) $ (990,668) $ 16,907 Consolidated Statements of Cash Flows Year Ended December 31, 2015 (in thousands) As revised As originally Effect of change Net loss $ (247,749) $ (251,408) $ 3,659 Adjustments to reconcile net loss to net cash used in operating activities: Accounts receivable (2,562) (679) (1,883) Other assets (3,639) (2,128) (1,511) Accrued expenses 20,077 19,646 431 Deferred revenues 92 788 (696) Cash and cash equivalents at beginning of period 256,861 — Cash and cash equivalents at end of period $ $ 230,146 $ — Year Ended December 31, 2016 (in thousands) As revised As originally Effect of change Net loss $ (374,224) $ (387,472) $ 13,248 Adjustments to reconcile net loss to net cash used in operating activities: Accounts receivable (3,634) (4,664) 1,030 Other assets (7,770) (7,685) (85) Accrued expenses 31,896 31,897 (1) Deferred revenues 309 14,501 (14,192) Cash and cash equivalents at beginning of period 230,146 — Cash and cash equivalents at end of period $ $ 785,877 $ — The most significant change above relates to the Company’s license, collaboration and other revenues and the impact of the potential payment to Zai Lab (Shanghai) Co., Ltd., or Zai Lab, upon exercise of the option to co-market niraparib in China, Hong Kong and Macao, or the China Territories. Under Topic 605, even though the Company believed the probability was remote that this option would be exercised, the Company had concluded that the contract price was not fixed or determinable under the revenue recognition criteria and accordingly no revenue had been previously recognized. Therefore, the upfront, non-refundable license fee of $15.0 million received by the Company in the fourth quarter of 2016 was deferred and recorded as a customer deposit as of December 31, 2016. Upon its adoption of Topic 606, the Company determined the probability was remote that it would exercise the option and accordingly, the potential future payments to Zai Lab had no impact on the transaction price. Further, the Company evaluated this option to co-market niraparib under Topic 606 and concluded that this option was not a repurchase right and accordingly recognized revenue in 2016 for the transaction price received as and when the performance obligations under this agreement were satisfied by the Company. In February 2018, the Company and Zai Lab entered into an amendment to the Collaboration, Development and License agreement between the parties, eliminating the Company’s co-marketing right. This amendment had no impact on the Company’s accounting conclusions under Topic 606. For further discussion of the adoption of this standard, see Note 13, “ Revenue Recognition ” and Note 14, “ License and Collaboration Agreements ”. In January 2017, the FASB issued ASU No. 2017-01, which clarifies the definition of a business. To be considered a business (instead of an asset), an acquisition would have to include an input and a substantive process that together significantly contribute to the ability to create outputs. The new guidance provides a framework to evaluate when an input and a substantive process are present (including for early stage companies that have not generated outputs). To be a business without outputs, there will now need to be an organized workforce. The new guidance narrows the definition of the term “outputs” to be consistent with how it is described in Topic 606. Under the final definition, an output is the result of inputs and substantive processes that provide goods or services to customers, other revenue, or investment income, such as dividends and interest. The new guidance is effective on a prospective basis for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years, with early adoption permitted. The Company has elected to early adopt this ASU effective January 1, 2017. The adoption of this guidance did not have a material impact on the Company’s consolidated financial statements, although this guidance could impact its accounting conclusions for certain future transactions, such as in-licensing agreements. New Accounting Pronouncements - Recently Issued In February 2016, the FASB issued ASU No. 2016-02, a comprehensive new lease accounting standard, which provides revised guidance on accounting for lease arrangements by both lessors and lessees and requires lessees to recognize a lease liability and a right-of-use asset for most leases. The new guidance is effective for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years, with early adoption permitted. The new standard must be applied using a modified retrospective transition approach that requires application of the new guidance for all periods presented. The Company is currently in the process of evaluating the impact that the adoption of this guidance will have on its consolidated financial statements and related disclosures. In August 2016, the FASB issued ASU No. 2016-15, which is intended to simplify and clarify how certain transactions are classified in the statement of cash f

Inventories

Inventories	12 Months Ended
	Dec. 31, 2017
Inventories
Inventories	3. Inventories The following table presents inventories (in thousands): December 31, 2016 2017 Raw materials $ 13,263 $ 17,876 Work in process 584 38,629 Finished goods 853 1,434 Total inventories $ 14,700 $ 57,939 Inventories are related to the Company’s approved products, ZEJULA and VARUBI. During the year ended December 31, 2017, the Company recorded a $16.7 million in lower of cost or market write-downs for excess and obsolete VARUBI inventories. In addition, a $1.6 million loss on firm purchase commitments was also recorded within the period. These charges resulted from the Company’s revision of its forecast of future sales of VARUBI, which in turn was related to the Company’s update to the VARUBI IV package insert in January 2018. The aggregate of $18.3 million in lower of cost or market write-downs and losses on firm purchase commitments affected the Company’s net loss per share applicable to common stockholders (basic and diluted) by $(0.34) for the year ended December 31, 2017. If future sales of ZEJULA or VARUBI are lower than expected, the Company may be required to record further write-downs of the value of such inventories. Inventory write-downs and losses on purchase commitments are recorded as components of cost of sales in the consolidated statements of operations and comprehensive loss.

Intangible Assets

Intangible Assets	12 Months Ended
	Dec. 31, 2017
Intangible Assets
Intangible Assets	4. Intangible Assets The following table presents intangible assets (in thousands): December 31, 2016 2017 Estimated useful life Acquired and in-licensed rights $ 15,000 $ 64,665 8-13 Years Less accumulated amortization (2,123) (8,281) Total intangible assets, net $ 12,877 $ 56,384 The increase in acquired and in-licensed rights as of December 31, 2017 was due to a milestone of $25.0 million paid to Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., or Merck, which was incurred upon the FDA approval of ZEJULA on March 27, 2017, a milestone of $10.0 million paid to OPKO Health, Inc., which was incurred upon the first commercial sale of VARUBY in Europe in May 2017, and a milestone of $14.7 million paid to Merck, which was incurred upon the approval of ZEJULA in Europe. The Company recorded $0.3 million, $1.9 million and $6.2 million, respectively, in amortization expense related to intangible assets during the years ended December 31, 2015, 2016 and 2017. Estimated future amortization expense for intangible assets as of December 31, 2017 is as follows (in thousands): Total 2018 $ 6,456 2019 6,456 2020 6,460 2021 6,456 2022 6,456 Thereafter 24,100 $ 56,384

Property and Equipment

Property and Equipment	12 Months Ended
	Dec. 31, 2017
Property and Equipment
Property and Equipment	5. Property and Equipment The following table presents property and equipment, at cost, and related accumulated depreciation (in thousands): December 31, 2016 2017 Furniture and fixtures $ 2,481 $ 4,212 Computer equipment and software 3,459 4,762 Leasehold improvements 3,190 6,314 Manufacturing equipment 124 350 Total property and equipment, at cost 9,254 15,638 Less accumulated depreciation and amortization (2,614) (5,986) Total property and equipment, net $ 6,640 $ 9,652 Total depreciation expense amounted to $0.8 million, $1.3 million and $3.4 million for the years ended December 31, 2015, 2016 and 2017, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2017
Accrued Expenses
Accrued expenses	6. Accrued Expenses The following table presents the components of accrued expenses (in thousands): December 31, 2016 2017 (as revised) Research and development $ 36,759 $ 55,949 Salaries, bonuses and other compensation 20,654 33,717 Inventory — 16,469 Product revenue allowances 1,407 22,847 Sales and marketing 3,177 6,701 Professional services 2,743 3,944 Royalties 2,059 6,552 Other 1,901 8,629 Total accrued expenses $ 68,700 $ 154,808

Debt

Debt	12 Months Ended
	Dec. 31, 2017
Debt.
Debt	7. Debt Our outstanding debt obligations consisted of the following (in thousands): December 31, 2016 2017 Convertible notes, net $ 131,775 $ 143,446 Term Loan (Tranche A) — 293,659 Total long-term debt $ 131,775 $ 437,105 Convertible Notes On September 29, 2014, in a registered underwritten public offering, the Company completed the issuance of $201.3 million aggregate principal amount of Convertible Notes. The Company received net proceeds of $194.7 million from the sale of the Convertible Notes, after deducting discounts, commissions and other expenses of $6.6 million. In conjunction with the sale of the Convertible Notes, the Company used $20.8 million of the net proceeds to enter into separate Capped Calls, as described below. The Convertible Notes are governed by the terms of a Senior Debt Securities Indenture, as supplemented by the First Supplemental Indenture relating to the Convertible Notes, collectively the Indenture, between the Company and U.S. Bank National Association, as trustee. The Convertible Notes bear interest at a rate of 3.00% per annum, payable semi-annually on April 1 and October 1, beginning from April 1, 2015, and will be convertible into cash, shares of the Company’s common stock or a combination of cash and shares of the Company’s common stock, at the Company’s election. The Convertible Notes will mature on October 1, 2021, unless earlier converted or repurchased in accordance with their terms. Prior to the close of business on the business day immediately preceding April 1, 2021, the Convertible Notes will be convertible only upon the occurrence of certain events and during certain periods as discussed below, and thereafter, at any time until the close of business on the second scheduled trading day immediately preceding the maturity date. The initial conversion price of the Convertible Notes is approximately $35.13 per share of common stock at an initial conversion rate of 28.4627 shares of the Company’s common stock per $1,000 principal amount of Convertible Notes, which represents a premium of approximately 35% over the last reported sale price of the Company’s common stock on September 23, 2014. The conversion rate is subject to adjustment from time to time upon the occurrence of certain events, including, but not limited to, the issuance of stock dividends and payment of cash dividends. At any time prior to the close of business on the business day immediately preceding April 1, 2021, holders may convert their Convertible Notes at their option only under the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on December 31, 2014 (and only during such calendar quarter), if the closing sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter in which the conversion occurs is greater than 130% of the conversion price on each applicable trading day; (2) during the five business day period after any ten consecutive trading day period, or the measurement period, in which the trading price per $1,000 principal amount of the Convertible Notes for each trading day of the measurement period was less than 98% of the product of the closing sale price of the Company’s common stock and the conversion rate on each such trading day; or (3) upon the occurrence of specified corporate events. On or after April 1, 2021 until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert all or any portion of their Convertible Notes, in multiples of $1,000 principal amount, at the option of the holder regardless of the foregoing circumstances. If a make-whole adjustment event, as described in the Indenture, occurs and a holder elects to convert its Convertible Notes in connection with such make-whole adjustment event, such holder may be entitled to an increase in the conversion rate as described in the Indenture. The Company may not redeem the Convertible Notes prior to the maturity date and no “sinking fund” is provided for the Convertible Notes, which means that the Company is not required to periodically redeem or retire the Convertible Notes. Upon the occurrence of certain fundamental changes involving the Company, holders of the Convertible Notes may require the Company to repurchase for cash all or part of their Convertible Notes at a repurchase price equal to 100% of the principal amount of the Convertible Notes to be repurchased, plus accrued and unpaid interest. The Indenture does not contain any financial covenants or restrictions on the payments of dividends, the incurrence of indebtedness or the issuance or repurchase of securities by the Company or any of its subsidiaries. The terms of the Indenture provide the Company with the option to settle the Convertible Notes in cash, common stock, or a combination of cash and common stock. As a result, in accordance with ASC Subtopic 470-20, Debt with Conversion and Other Options , the Company separately accounts for the liability and equity components of the Convertible Notes by allocating the principal between the liability component and the embedded conversion option, or equity component. Based on market data available for publicly traded, senior, unsecured corporate bonds issued by companies in the same industry and with similar maturity, the Company estimated the implied interest rate, assuming no conversion option. Assumptions used in the estimate represent what market participants would use in pricing the liability component, including market interest rates, credit standing, and yield curves, all of which are defined as Level 2 observable inputs. The estimated implied interest rate was applied to the Convertible Notes, which resulted in a fair value of the liability component of $113.4 million upon issuance, calculated as the present value of implied future payments based on the $201.3 million aggregate principal amount. The equity component of the Convertible Notes was recognized as a debt discount, recorded in additional paid-in capital, and represents the difference between the aggregate principal of the Convertible Notes and the fair value of the Convertible Notes without conversion option on their issuance date. The debt discount is amortized to interest expense using the effective interest method over seven years, or the life of the Convertible Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The Company’s outstanding convertible note balances at December 31, 2017 consisted of the following (in thousands): December 31, 2017 Liability component Principal $ 201,250 Less: debt discount and issuance costs, net (57,804) Net carrying amount $ 143,446 Equity component $ 87,843 In connection with the issuance of the Convertible Notes, the Company incurred issuance costs, primarily consisting of underwriting, legal and other professional fees, which the Company allocated to the liability and equity components in a manner consistent with the allocation of the principal, as described above. Of the total $6.6 million of debt issuance costs, $2.9 million were allocated to the equity component and recorded as a reduction to additional paid-in capital and $3.7 million were allocated to the liability component and recorded as a reduction in the carrying amount of the convertible note. The portion allocated to the liability component is amortized to interest expense over the expected life of the Convertible Notes using the effective interest method. The Company determined the expected life of the debt was equal to the seven year contractual term of the Convertible Notes. As of December 31, 2017, the carrying value of the Convertible Notes was $143.4 million and the fair value of the Convertible Notes approximated $499.1 million. The effective interest rate on the liability component is 12.9%. The following table sets forth total interest expense recognized related to the Convertible Notes during the years ended December 31, 2016 and 2017 (in thousands): Years Ended December 31, 2016 2017 Contractual interest expense $ 6,037 $ 6,038 Amortization of debt discount 9,851 11,126 Amortization of debt issuance costs 599 545 Total interest expense $ 16,487 $ 17,709 The Company has evaluated the Indenture for derivatives pursuant to ASC Topic 815, Derivatives and Hedging , and identified an embedded derivative that requires bifurcation as the feature is not clearly and closely related to the host instrument. The embedded derivative is a default provision, which could require additional interest payments. The Company has determined that the fair value of this embedded derivative was nominal as of December 31, 2017. In conjunction with the offering of the Convertible Notes, the Company entered into privately-negotiated Capped Calls with certain counterparties. Each Capped Call is an integrated instrument consisting of a call option on the Company’s common stock purchased by the Company from the counterparties with an exercise price equal to the conversion price of $35.13 per share for the underlying number of shares and a cap component that incorporates a cap price of $45.54 per share. The cap component is economically equivalent to a call option sold by the Company to the counterparties for the underlying number of shares with an exercise price of $45.54 per share. As an integrated instrument, the settlement of the Capped Calls coincides with the maturity date of the Convertible Notes. The aggregate cost of the Capped Calls was $20.8 million and was recorded in stockholders’ equity and will not be remeasured. 2017 Term Loan Agreement In November 2017, the Company entered into a loan agreement, or the Loan Agreement, with BioPharma Credit PLC and affiliates, or the Lenders. The Lenders agreed to provide up to an aggregate principal amount of $500.0 million in two tranches, with the first tranche equal to $300.0 million, or Tranche A, and the second in an amount between $50.0 million and $200.0 million at the Company’s discretion, or Tranche B. The Company drew Tranche A on December 6, 2017 with a maturity date of December 6, 2024. Tranche B is available for draw at the Company’s option, on 90 days’ notice, from June 30, 2018 until December 20, 2018 and if drawn by the Company, will also have a maturity date of December 6, 2024. Borrowings under the Tranche A and Tranche B loans bear interest at a rate equal to the London Interbank Offered Rate, or LIBOR, plus an applicable margin of 8% per annum and 7.5% per annum, respectively (with the LIBOR rate subject to a floor of 1% and cap equal to the LIBOR rate as of the Tranche A closing date plus 1.5%). The loans have an up-front fee of 2% on the funded amount of each tranche, payable at the applicable closing date. The obligations of the Company under the Loan Agreement are guaranteed by the Company’s wholly-owned U.S. subsidiary, TESARO Securities Corporation, and are secured by security interests in (i) all of the Company’s owned or exclusively licensed U.S. registered patents and trademarks relating to the research, development, manufacture, production, use, commercialization, marketing, importing, storage, transport, offer for sale, distribution or sale of VARUBI (rolapitant) or ZEJULA (niraparib) in the U.S., (ii) rights under any U.S. new drug application relating to VARUBI and ZEJULA, (iii) 100% of the equity interests in wholly owned domestic subsidiaries and 65% of the equity interests in directly owned foreign subsidiaries, in each case of the Company and any guarantor, and (iv) cash held in all deposit accounts of the Company and any guarantor. The Company has the option to prepay, in whole or in part, Tranche A or Tranche B, subject to a prepayment premium and a make-whole amount, if applicable. If any prepayment occurs prior to the 24-month anniversary of the respective closing date, a make-whole amount equal to the sum of all interest accruing from the prepayment date through the 24-month anniversary of the respective closing date, and a 3% premium would also apply to such repayment. If the prepayment occurs prior to the 36-month anniversary, a 2% premium would apply to such repayment, and a 1% premium if the prepayment occurs prior to the 48-month anniversary. The Company is obligated to make quarterly repayments of principal in an amount equal to 3%, starting December 31, 2019 for the Tranche A loan amount with any remaining balance payable on the final maturity date. Interest on the outstanding Tranche A loan amount is payable quarterly in arrears. There are no financial covenants associated with the Loan Agreement; however, there are customary representations and warranties and customary affirmative and negative covenants, including among other things, restrictions (subject to various exceptions) on transfer of intellectual property related to the collateral, indebtedness, liens, prepayment of other indebtedness and payment of dividends and stock repurchases by the Company. The Loan Agreement also includes events of default, the occurrence and continuation of any of which provides the Lenders the right to exercise remedies against the Company and the collateral securing the loans under the Loan Agreement, including cash. These events of default include, among other things, failure to pay any amounts due under the Loan Agreement, insolvency, the occurrence of a material adverse change in the ability of the Company to perform its obligations under the Loan Agreement, the occurrence of any default under certain other indebtedness and a final judgment against the Company in an uninsured amount greater than $10.0 million. The Tranche A loan was recorded on the consolidated balance sheets, net of a debt discount of $6.0 million in upfront fees assessed by the Lenders at the time of borrowing. The debt discount and deferred financing costs of $0.4 million are being amortized to interest expense using the effective interest method over the same term. The effective annual interest rate of the outstanding debt under Tranche A loan is approximately 10.0%. During the year ended December 31, 2017, the Company recognized $2.0 million of interest expense related to the Tranche A Loan, including $0.1 million related to the accretion of debt discount and amortization of deferred financing costs. Future annual principal payments on the Company’s long-term debt as of December 31, 2017 were as follows (in thousands): Total 2018 $ — 2019 9,000 2020 36,000 2021 237,250 2022 36,000 Thereafter 183,000 Total $ 501,250

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2017
Common Stock Transactions
Stockholders' Equity	8. Stockholders’ Equity As of December 31, 2017, the authorized capital stock of the Company consisted of 10,000,000 shares of preferred stock and 100,000,000 shares of common stock, both with a par value of $0.0001, of which no shares of preferred stock were issued or outstanding and 54,464,039 shares of common stock were issued and outstanding. Preferred Stock The Company’s certificate of incorporation authorizes its board of directors to issue preferred stock from time to time in one or more series. The rights, preferences, restrictions, qualifications and limitations of such stock are determined by the board of directors. Common Stock In March 2015, the Company sold 3,755,000 shares of common stock, in an underwritten public offering at a price to the public of $51.00 per share, resulting in gross proceeds of approximately $191.5 million. Net proceeds to the Company after deducting fees, commissions and other expenses related to the offering were approximately $179.8 million. The shares were issued pursuant to an automatic shelf registration statement on Form S-3. In March 2016, the Company sold 4,404,658 shares of common stock in a private placement offering at a price of $35.19 per share, to certain accredited investors, including funds affiliated with three of its directors and current investors, resulting in gross proceeds of approximately $155.0 million. The price per share was equal to the volume weighted average price for the ten-day period ending on March 17, 2016. There were no placement agents used for this financing. The sale and issuance of the shares of common stock in the private placement was made in reliance on the exemption afforded by Section 4(a)(2) under the Securities Act of 1933 and Regulation D promulgated under the Securities Act. In April 2016, the Company sold 1,130,198 shares of common stock to Johnson & Johnson Innovation – JJDC, Inc., or JJDC, at a price of $44.24 per share, for an aggregate purchase price of approximately $50.0 million. The price per share was equal to the volume weighted average price for the five-day period ending on April 4, 2016. There were no placement agents used, or any underwriting discounts or commissions paid in connection with the transaction. The sale and issuance of the shares of common stock was made in reliance on the exemption afforded by Section 4(a)(2) under the Securities Act of 1933 and Regulation D promulgated under the Securities Act. In July 2016, the Company sold 5,347,500 shares of common stock, in an underwritten public offering at a price to the public of $81.00 per share, resulting in gross proceeds of approximately $433.1 million. Net proceeds to the Company after deducting fees, commissions and other expenses related to the offering were approximately $408.9 million. The shares were issued pursuant to an automatic shelf registration statement on Form S-3. In November 2016, the Company sold 1,750,000 shares of common stock, in an underwritten public offering at a price to the public of $135.00 per share, resulting in gross proceeds of approximately $236.3 million. Net proceeds to the Company after deducting fees, commissions and other expenses related to the offering were approximately $224.2 million. The shares were issued pursuant to an automatic shelf registration statement on Form S-3. The holders of common stock are entitled to one vote per share on all matters to be voted upon by the stockholders of the Company. Subject to the preferences that may be applicable to any outstanding shares of preferred stock, the holders of common stock are entitled to receive ratably such dividends, if any, as may be declared by the Company’s board of directors.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
Stock-Based Compensation
Stock-Based Compensation	9. Stock-Based Compensation The following table presents stock-based compensation expense as reflected in the Company’s consolidated statements of operations and comprehensive loss (in thousands): Years Ended December 31, 2015 2016 2017 Research and development $ 11,082 $ 19,783 $ 30,810 Selling, general and administrative 14,832 28,672 59,616 Total stock-based compensation expense $ 25,914 $ 48,455 $ 90,426 The Company maintains several equity compensation plans, including the TESARO, Inc. 2012 Omnibus Incentive Plan, or the 2012 Incentive Plan, the TESARO, Inc. 2010 Stock Incentive Plan, or the 2010 Incentive Plan, the TESARO, Inc. 2015 Non-Employee Director Stock Incentive Plan, or the 2015 Director Plan, and the TESARO, Inc. 2012 Employee Stock Purchase Plan, or the 2012 ESPP. Terms of stock award agreements, including vesting requirements, are determined by the board of directors, subject to the provisions of the individual plans. To date, stock option awards granted to employees by the Company generally vest either monthly over four years, or 25% one year from the vesting start date and 75% in equal installments over the subsequent thirty-six (36) months, and are exercisable from the date of grant for a period of ten years. RSUs granted to employees by the Company generally vest annually over four years in equal annual installments of 25% each. 2010 Stock Incentive Plan In connection with the Company’s formation, the Company adopted the 2010 Incentive Plan, under which it was authorized to grant stock-based awards of up to 1,981,130 shares of common stock as of January 1, 2012. As of April 27, 2012, the Company ceased making awards under the 2010 Incentive Plan and the remaining 6,857 shares available for future grants were added to the total number of shares reserved for issuance under the 2012 Incentive Plan. For options granted under the 2010 Incentive Plan, the exercise price equaled the estimated fair value of the common stock as determined by the board of directors on the date of grant. As of December 31, 2017, there are no shares available for grant under the 2010 Incentive Plan. 2012 Omnibus Incentive Plan On April 27, 2012, the stockholders of the Company approved the 2012 Incentive Plan, which had been previously adopted by the board of directors. Upon effectiveness of the 2012 Incentive Plan, the Company ceased making awards under the 2010 Incentive Plan. The 2012 Incentive Plan allows the Company to grant awards for up to 1,428,571 shares of common stock plus the number of shares of common stock available for grant under the 2010 Incentive Plan as of the effectiveness of the 2012 Incentive Plan (which is an additional 6,857 shares) plus that number of shares of common stock related to awards outstanding under the 2010 Incentive Plan that terminate by expiration, forfeiture, cancellation, cash settlement or otherwise. The number of shares available for grants of awards under the 2012 Incentive Plan is increased automatically on January 1 by a number of shares of common stock equal to the lesser of 4% of the shares of common stock outstanding at such time or the number of shares determined by the Company’s board of directors. Accordingly, effective January 1, 2017 and 2018, the number of shares authorized for issuance under the 2012 Incentive Plan was increased by 2,144,867 shares and 2,178,561 shares, respectively. Awards under the 2012 Incentive Plan may include the following award types: stock options, which may be either incentive stock options or nonqualified stock options; stock appreciation rights; restricted stock; RSUs; dividend equivalent rights; performance shares; performance units; cash-based awards; other stock-based awards, including unrestricted shares; or any combination of the foregoing. The exercise price of stock options granted under the 2012 Incentive Plan is equal to the closing price of a share of the Company’s common stock on the grant date. As of December 31, 2017, there were 1,810,240 shares available for grant under the 2012 Incentive Plan, prior to taking into account the additional shares authorized for issuance as of January 1, 2018, as described above. 2015 Director Plan On May 14, 2015, the stockholders of the Company approved the 2015 Director Plan, which had been previously adopted by the board of directors in order to have a plan in addition to the 2012 Incentive Plan for purposes of granting awards to non-employee directors. On May 11, 2016, the Company’s stockholders approved certain amendments to the 2015 Director Plan to limit the number of shares of the Company's common stock subject to awards granted in a calendar year to any non-employee director to 50,000 shares, and to affirm the number of shares reserved for issuance under the plan. The 2015 Director Plan allows the Company to grant awards for up to 500,000 shares of common stock. Awards under the 2015 Director Plan may include the following award types: stock options; stock appreciation rights; restricted stock; RSUs; unrestricted stock; or any combination of the foregoing. The exercise price of stock options granted under the 2015 Director Plan is equal to the closing price of a share of the Company’s common stock on the grant date. As of December 31, 2017, there were 198,433 shares available for grant under the 2015 Director Plan. Stock Options The following table presents a summary of the Company’s stock option activity and related information: Weighted-average Weighted-average Aggregate exercise price per remaining contractual intrinsic value Shares share term (years) (in thousands) Outstanding at December 31, 2016 6,978,621 $ 40.65 $ 655,099 Granted 693,112 160.53 Exercised (597,209) 43.34 Cancelled (166,211) 59.31 Outstanding at December 31, 2017 6,908,313 $ 52.00 6.8 $ 276,640 Vested at December 31, 2017 4,297,650 $ 33.47 6.0 $ 219,374 The fair value of each stock option was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions: Years Ended December 31, 2015 2016 2017 Dividend yield — — — Volatility 63% - 65% 57% - 59% 60% - 64% Risk-free interest rate 1.35% - 1.95% 1.07% - 2.10% 1.79% - 2.30% Expected term (years) 5.50 - 6.08 5.50 - 6.08 5.50 - 6.08 The Company uses the simplified method as prescribed by U.S. Securities and Exchange Commission Staff Accounting Bulletin No. 107, Share-Based Payment , to calculate the expected term, as it does not have sufficient historical exercise data to provide a reasonable basis upon which to estimate the expected term for options granted. The expected term is applied to all stock option grants as a whole, as the Company does not expect substantially different exercise or post-vesting termination behavior among its population. The computation of expected volatility is based on a blend of the historical volatility of the company and the volatility of a representative group of public biopharmaceutical companies with similar characteristics to the Company, including stage of product development, market capitalization and therapeutic focus. The risk-free interest rate is based on a U.S. Treasury instrument whose term is consistent with the expected term of the stock options. The value of the award is recognized as expense on a straight-line basis over the requisite service period and is adjusted for pre-vesting forfeitures in the period in which the forfeitures occur. For stock awards that have a performance condition, the Company recognizes compensation expense based on its assessment of the probability that the performance condition will be achieved, using an accelerated attribution model, over the explicit or implicit service period. The weighted-average grant date fair values of options granted in the years ended December 31, 2015, 2016 and 2017 were $32.05, $32.13 and $94.50 per share, respectively. The aggregate intrinsic value of options exercised during the years ended December 31, 2015, 2016 and 2017 was $11.8 million, $37.4 million and $57.1 million, respectively. The intrinsic value of a stock option is the amount by which the fair market value of the underlying stock on the exercise date exceeds the exercise price of the stock option. In June 2015, June 2016, and June 2017 as provided for under the 2012 Incentive Plan and the 2015 Director Plan, the Company issued 3,429, 6,027 and 3,111 shares of common stock, respectively, to certain non-employee board members who elected to receive shares of common stock in lieu of cash, as payment of fees owed them for services as members of the Company’s board of directors. At December 31, 2017, there was $110.3 million of total unrecognized compensation cost related to unvested stock options, which the Company expects to recognize over a remaining weighted-average period of 2.1 years. Restricted Stock Units The following table presents a summary of the Company’s RSU activity and related information: Weighted-average grant date fair Shares value per share Unvested restricted stock units at December 31, 2016 760,123 $ 58.55 Granted 656,751 162.79 Vested (199,654) 59.48 Forfeited (58,102) 107.34 Unvested restricted stock units at December 31, 2017 1,159,118 $ 115.01 In July 2016, the Company issued 15,000 RSUs with service and performance conditions to certain employees, of which 11,512 vested during the year ended December 31, 2017. Vesting of these awards is contingent on the occurrence of certain milestone events and fulfillment of any remaining service condition. As a result, the related compensation cost is recognized as an expense when achievement of the milestone is considered probable. The expense recognized for these awards is based on the grant date fair value of the Company’s common stock multiplied by the number of units granted. The Company recognized $0.4 million and $0.9 million of related expense during the years ended December 31, 2016 and 2017, respectively. The weighted-average grant date fair values of RSUs granted during the years ended December 31, 2015, 2016 and 2017 were $56.00, $58.47, and $162.79 per share, respectively. The total grant date fair value of RSUs that vested during the years ended December 31, 2015, 2016 and 2017 was $0.5 million, $1.1 million and $11.9 million, respectively, based upon the number of RSUs vested multiplied by the closing stock price of the Company’s common stock on the grant date. As of December 31, 2017, there was approximately $107.3 million of unrecognized compensation cost related to unvested RSUs that the Company expects to recognize over a remaining weighted-average period of approximately 2.8 years. Employee Stock Purchase Plan On June 6, 2012, the board of directors adopted the 2012 ESPP, and the stockholders approved it on June 18, 2012, to be effective in connection with the closing of the Company’s initial public offering. A total of 275,000 shares of common stock were originally approved for future issuance under the 2012 ESPP pursuant to purchase rights granted to the Company’s employees or to employees of the Company’s designated subsidiaries. As of December 31, 2017, 151,859 shares remained available for issuance. The 2012 ESPP provides for consecutive six-month offering periods, during which participating employees may elect to have a portion of their compensation withheld and used for the purchase of common stock at the end of each offering period. The purchase price is equal to 85% of the lower of the fair market value of a share of common stock on the first trading date of each offering period or the fair market value of a share of common stock on the last trading day of the offering period, and is limited by participant to $25,000 in fair value of common stock per year. The 2012 ESPP will terminate on June 6, 2022, the tenth anniversary of the date of initial adoption of the plan. For the years ended December 31, 2015, 2016 and 2017, the Company issued a total of 20,601, 42,478 and 42,386 shares of common stock, respectively, under the 2012 ESPP. The following table presents stock-based compensation expense by type of award (in thousands): Years Ended December 31, 2015 2016 2017 Stock options $ 24,862 $ 40,030 $ 57,500 Restricted stock units (including performance-based RSUs) 742 7,502 31,498 Employee stock purchase plan 310 923 1,428 Total $ 25,914 $ 48,455 $ 90,426

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Taxes
Income Taxes	10. Income Taxes The following table presents the components of income (loss) before the provision for (benefit from) income taxes during the years ended December 31, 2015, 2016, and 2017 (in thousands): Years Ended December 31, 2015 2016 2017 (as revised) (as revised) United States $ (210,744) $ (298,969) $ (399,265) Foreign (37,005) (73,780) (95,537) (Loss) income before provision for (benefit from) income taxes $ (247,749) $ (372,749) $ (494,802) Provisions for income taxes for the years ended December 31, 2015, 2016 and 2017 are as follows (in thousands): Years Ended December 31, 2015 2016 2017 Current: Federal $ — $ — $ — State — 3 29 Foreign — 1,597 1,157 — 1,600 1,186 Deferred: Federal — — — State — — — Foreign — (125) 138 — (125) 138 Provision for income taxes $ — $ 1,475 $ 1,324 The following table presents a reconciliation of income tax expense (benefit) at the statutory federal income tax rate to the effective income tax rate as reflected in the consolidated financial statements: Years Ended December 31, 2015 2016 2017 (as revised) (as revised) Federal income tax (benefit) expense at statutory rate (34.0) % (35.0) % (35.0) % State income tax (benefit) expense (2.3) (0.4) (1.6) Permanent items 0.2 (0.1) (0.7) Foreign rate differential 5.0 6.0 4.2 Federal research and development credit (1.7) (11.1) (11.8) Tax rate change — — 31.5 Change in valuation allowance 32.8 40.6 12.5 Other 1.2 Effective income tax rate % % % The Company’s effective rate for the year ended December 31, 2017 compared to the year ended December 31, 2016 decreased primarily as a result of China withholding taxes on the up-front license payment received from Zai Lab during the year ended December 31, 2016, offset by increases as a result of subsidiary operations in foreign tax jurisdictions during the year ended December 31, 2017. The Company accounts for income taxes in accordance with ASC Topic 740. Deferred income tax assets and liabilities are determined based upon temporary differences between the financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. The following table presents the principal components of the Company’s deferred tax assets and liabilities (in thousands): December 31, 2016 2017 Deferred tax assets: (as revised) Federal net operating loss carryforwards $ 231,663 $ 204,495 State net operating loss carryforwards 18,027 26,225 Depreciation and amortization 18,840 16,435 Stock-based compensation 21,393 24,017 Tax credit carryforwards 54,950 107,944 Other 7,374 14,769 Total deferred tax assets 352,247 393,885 Less: valuation allowance (334,468) (384,453) Net deferred tax assets 17,779 9,432 Deferred tax liability: Debt discount on convertible notes (17,654) (9,432) Net deferred taxes $ 125 $ — Effective January 1, 2017, the Company adopted ASC Topic 606, using the full retrospective transition method. Under this method, the Company has revised its consolidated financial statements for the years ended December 31, 2015 and 2016, and applicable interim periods within those years, as if Topic 606 had been effective for those periods. The adoption of this guidance did not have a significant impact on the Company’s related tax disclosures. On December 22, 2017, the Tax Cuts and Jobs Act of 2017, or the Tax Act, was signed into law, resulting in significant changes to the U.S. corporate income tax system. These changes include a reduction of the federal statutory rate from 35% to 21%, reduction of certain tax credits, limitations on deductibility of interest expense and executive compensation, and limitations on the use of net operating loss, or NOL, carryforwards. The Tax Act also transitions U.S. international taxation from a worldwide system to a territorial system and includes provisions to prevent base erosion on foreign earnings, which has the effect of subjecting certain earnings of the Company’s foreign subsidiaries to current U.S. taxation. These changes are generally effective beginning in 2018. The Tax Act also includes a one-time mandatory deemed repatriation tax on accumulated foreign subsidiaries’ previously untaxed foreign earnings, or the Transition Toll Tax. The Transition Toll Tax can be paid over an eight-year period, starting in 2018 and will not be subject to interest. The Company has recognized the provisional tax impacts related to the Transition Toll Tax and the revaluation of deferred tax assets and liabilities in its consolidated financial statements for the year ended December 31, 2017. The Tax Act did not have a significant impact on the Company’s consolidated financial statements for the year ended December 31, 2017 because the Company maintains a full valuation allowance on its net operating losses and other deferred tax assets. In addition, the Company has an accumulated deficit from its foreign operations and does not have an associated liability from the Transition Toll Tax. The Tax Act subjects a U.S. stockholder to tax on global intangible low-taxed income, or GILTI, earned by certain foreign subsidiaries. Companies can make an accounting policy election to either recognize deferred taxes for temporary basis differences expected to reverse as GILTI in future years, or provide for the tax expense related to GILTI in the year the tax is incurred. Given the complexity of the GILTI provisions, the Company is still evaluating the effects of GILTI provisions and has not yet determined its accounting policy. In accordance with SEC Staff Accounting Bulletin No. 118, the Company’s preliminary estimate of the impact of the Tax Act is subject to the finalization of management's analysis related to certain matters, such as developing interpretations of the provisions of the Tax Act, changes to certain estimates and amounts related to the earnings and profits of certain subsidiaries and the filing of the Company’s tax returns. U.S. Treasury regulations, administrative interpretations or court decisions interpreting the Tax Act may require further adjustments and changes in the Company’s estimates, which could have a material adverse effect on the Company’s business, results of operations or financial condition. The Company’s final determination of the impact of the Tax Act will be completed as additional information becomes available, but no later than one year from its enactment. ASC Topic 740 requires a valuation allowance to reduce the deferred tax assets reported if, based on the weight of available evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. After consideration of all the evidence, both positive and negative, the Company has recorded full valuation allowances against its domestic and foreign deferred tax assets at December 31, 2017, because management has determined that is it more likely than not that these assets will not be realized. The valuation allowance increased by $50.0 million from December 31, 2016 to December 31, 2017, primarily due to increases in operating losses and tax credits, partially offset by decreases reflecting the change in the U.S. corporate income tax rate from 35% to 21% resulting from the Tax Act. As of December 31, 2017, the Company had cumulative federal, state and foreign NOL carryforwards of $963.9 million and $449.5 million and $14.2, million respectively. The federal, state and foreign NOL carryforwards will expire at various dates through 2037, if not utilized, and are fully offset by a valuation allowance. As of December 31, 2017, the Company had federal general business and state research and development tax credit carryforwards of approximately $102.1 million and $7.4 million, respectively, available to reduce future tax liabilities. The federal general business and state research and development tax credits will expire at various dates through 2037. The federal and state tax credit carryforwards are fully offset by a valuation allowance. Under the provisions of the Internal Revenue Code, the NOL and tax credit carryforwards are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. NOL and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant stockholders over a three-year period in excess of 50 percent, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has completed several financings since its inception that it believes may have resulted in a change in control as defined by Sections 382 and 383 of the Internal Revenue Code. The Company and its subsidiaries file income tax returns in the United States, as well as various state and foreign jurisdictions. Generally, the tax years 2014 through 2016 remain open to examination by the major taxing jurisdictions to which the Company is subject. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service, or state or foreign tax authorities, to the extent utilized in a future period. A reconciliation of the beginning and ending balances of unrecognized tax benefits is as follows (in thousands): 2016 2017 Balance at January 1 $ — $ 7,744 Increases related to prior year tax positions 4,304 4,010 Increases related to current year tax positions 3,440 9,926 Reductions for tax positions of prior periods — — Decreases related to lapse of applicable statute of limitations — — Decreases related to settlements with tax authorities — — Balance at December 31 $ 7,744 $ 21,680 During the year ended December 31, 2017, the Company established gross reserves of $4.0 million and $9.9 million related to research and development tax credits and the allocation of taxable income to the various jurisdictions where the Company is subject to tax, respectively. The Company’s policy is to record estimated interest and penalties related to the underpayment of income taxes as a component of its income tax provision. As of December 31, 2016 and 2017, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company’s consolidated statement of operations.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2017
Employee Benefit Plans
Employee Benefit Plans	11. Employee Benefit Plans In 2010, the Company adopted a retirement plan, which is qualified under Section 401(k) of the Internal Revenue Code, for its U.S. employees. The plan allows eligible employees to defer, at the employee’s discretion, pre-tax or post-tax compensation up to the IRS annual limits. Company contributions may be made at the discretion of the board of directors. Effective as of January 1, 2012, the Company amended its 401(k) plan to provide for employer matching contributions equal to (1) 100% of employee deferral contributions up to a deferral rate of 3% of compensation, plus (2) 50% of employee deferral contributions up to a deferral rate of an additional 2% of compensation. During the years ended December 31, 2015, 2016 and 2017, the Company made aggregate matching contributions of $1.0 million, $2.2 million and $4.2 million, respectively. The Company maintains a pension plan covering employees of its wholly owned subsidiary in Switzerland. This plan is considered a defined benefit plan and is a government-mandated retirement fund that provides benefits to employees upon retirement, death, or disability. Employer and employee contributions are made based on various percentages of salaries and wages that vary based on employee age and other factors. As of December 31, 2017, the plan had an unfunded net pension obligation of approximately $6.5 million and plan assets of approximately $9.9 million. In 2017, the Company recognized expense of $1.3 million related to this plan.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies
Commitments and Contingencies	12. Commitments and Contingencies The Company leases office space for its corporate headquarters in Waltham, Massachusetts under a non-cancelable operating lease agreement and an indenture of lease. Since the lease term of the non-cancelable operating lease agreement commenced on April 1, 2013, the Company has executed seven amendments to increase its leased space under that lease to a total of approximately 180,000 square feet as of December 31, 2017. The lease term, as amended, continues through June 30, 2020. The lease agreement, as amended, provides for varying periods of free rent with respect to portions of the leased premises and tenant improvement allowances of $3.0 million. On December 18, 2017, the Company entered into an indenture of lease for approximately 83,000 additional square feet of leased office space. The indenture of lease continues through December 18, 2022 and provides for tenant improvement allowances of $2.9 million. The Company also leases office space in several locations throughout Europe. The Company recognizes rent expense on a straight-line basis over the respective lease term including any free rent periods and tenant allowances. The following table presents future minimum rental commitments, by fiscal year and in the aggregate, as of December 31, 2017 (in thousands): Operating Leases 2018 $ 9,890 2019 11,616 2020 7,713 2021 3,766 2022 3,566 Thereafter 2,291 Total minimum lease payments $ 38,842 The Company recorded $2.1 million, $3.4 million and $5.4 million in rent expense for the years ended December 31, 2015, 2016 and 2017, respectively. The Company has entered into agreements with certain vendors for the provision of services, including services related to data management clinical operation support services, that the Company is not contractually able to terminate for convenience and avoid any and all future obligations to the vendors. Under such agreements, the Company is contractually obligated to make certain minimum payments to the vendors, with the exact amounts in the event of termination to be based on the timing of the termination and the exact terms of the agreement. Litigation and Other Proceedings The Company may periodically become subject to legal proceedings and claims arising in connection with ongoing business activities, including claims or disputes related to patents that have been issued or that are pending in the field of research on which the Company is focused. A putative class action complaint was filed on January 17, 2018 in the United States District Court for the District of Massachusetts, entitled Roger Bowers v. TESARO Incorporated (sic), et. al., Case No. 18-10086. The complaint alleges that the Company and its Chief Executive Officer and its Chief Financial Officer violated certain federal securities laws, specifically under Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, and Rule 10b-5 thereunder. The plaintiff seeks unspecified damages on behalf of a purported class of purchasers of the Company’s common stock between March 14, 2016 and January 12, 2018. The Court has not set a trial date for this matter. The Company believes that the allegations contained in the complaint are without merit and intends to defend the case vigorously. The Company has not recorded an estimated liability associated with this legal proceeding as it does not believe that such a liability is probable.

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2017
Revenue Recognition [Abstract]
Revenue Recognition	13. Revenue Recognition Product Revenue, Net The Company sells its products principally to a limited number of specialty distributors and specialty pharmacy providers in the U.S. and the EU, or collectively, its Customers. These Customers subsequently resell the Company’s products to health care providers and patients. In addition to distribution agreements with Customers, the Company enters into arrangements with health care providers and payors that provide for government-mandated and/or privately-negotiated rebates, chargebacks and discounts with respect to the purchase of the Company’s products. Revenues from product sales are recognized when the Customer obtains control of the Company’s product, which occurs at a point in time, typically upon delivery to the Customer. When the Company performs shipping and handling activities after the transfer of control to the Customer (e.g., when control transfers prior to delivery), they are considered as fulfillment activities, and accordingly, the costs are accrued for when the related revenue is recognized. Taxes collected from Customers relating to product sales and remitted to governmental authorities are excluded from revenues. The Company expenses incremental costs of obtaining a contract as and when incurred if the expected amortization period of the asset that the Company would have recognized is one year or less. Reserves for Variable Consideration Revenues from product sales are recorded at the net sales price (transaction price), which includes estimates of variable consideration for which reserves are established and which result from discounts, returns, chargebacks, rebates, co-pay assistance and other allowances that are offered within contracts between the Company and its Customers, health care providers, payors and other indirect customers relating to the Company’s sales of its products. These reserves are based on the amounts earned or to be claimed on the related sales and are classified as reductions of accounts receivable (if the amount is payable to the Customer) or a current liability (if the amount is payable to a party other than a Customer). Where appropriate, these estimates take into consideration a range of possible outcomes that are probability-weighted for relevant factors such as the Company’s historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contract. The amount of variable consideration that is included in the transaction price may be constrained, and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results in the future vary from the Company’s estimates, the Company will adjust these estimates, which would affect net product revenue and earnings in the period such variances become known. Trade Discounts and Allowances: The Company generally provides Customers with discounts that include incentive fees that are explicitly stated in the Company’s contracts and are recorded as a reduction of revenue in the period the related product revenue is recognized. In addition, the Company receives sales order management, data and distribution services from certain Customers. To the extent the services received are distinct from the Company’s sale of products to the Customer, these payments are classified in selling, general and administrative expenses in the consolidated statements of operations and comprehensive loss of the Company. Product Returns: Consistent with industry practice, the Company generally offers Customers a limited right of return based on the product’s expiration date for product that has been purchased from the Company, which lapses upon shipment to a patient. The Company estimates the amount of its product sales that may be returned by its Customers and records this estimate as a reduction of revenue in the period the related product revenue is recognized. The Company currently estimates product return liabilities using available industry data and its own historical sales information, including its visibility into the inventory remaining in the distribution channel. Provider Chargebacks and Discounts: Chargebacks for fees and discounts to providers represent the estimated obligations resulting from contractual commitments to sell products to qualified healthcare providers at prices lower than the list prices charged to Customers who directly purchase the product from the Company. Customers charge the Company for the difference between what they pay for the product and the ultimate selling price to the qualified healthcare providers. These reserves are established in the same period that the related revenue is recognized, resulting in a reduction of product revenue and accounts receivable. Chargeback amounts are generally determined at the time of resale to the qualified healthcare provider by Customers, and the Company generally issues credits for such amounts within a few weeks of the Customer’s notification to the Company of the resale. Reserves for chargebacks consist of credits that the Company expects to issue for units that remain in the distribution channel inventories at each reporting period end that the Company expects will be sold to qualified healthcare providers, and chargebacks that Customers have claimed but for which the Company has not yet issued a credit. Government Rebates: The Company is subject to discount obligations under state Medicaid programs and Medicare. The Company estimates its Medicaid and Medicare rebates based upon a range of possible outcomes that are probability-weighted for the estimated payor mix. These reserves are recorded in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability that is included in accrued expenses on the consolidated balance sheet. For Medicare, the Company also estimates the number of patients in the prescription drug coverage gap for whom the Company will owe an additional liability under the Medicare Part D program. The Company’s liability for these rebates consists of invoices received for claims from prior quarters that have not been paid or for which an invoice has not yet been received, estimates of claims for the current quarter, and estimated future claims that will be made for product that has been recognized as revenue, but remains in the distribution channel inventories at the end of each reporting period. Payor Rebates: The Company contracts with various private payor organizations, primarily insurance companies and pharmacy benefit managers, for the payment of rebates with respect to utilization of its products. The Company estimates these rebates and records such estimates in the same period the related revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability. Other Incentives: Other incentives that the Company offers include voluntary patient assistance programs, such as co-pay assistance programs, which are intended to provide financial assistance to qualified commercially insured patients with prescription drug co-payments required by payors. The calculation of the accrual for co-pay assistance is based on an estimate of claims and the cost per claim that the Company expects to receive associated with product that has been recognized as revenue, but remains in the distribution channel inventories at the end of each reporting period. To date, the Company’s sources of product revenue have been U.S. sales of ZEJULA and VARUBI, and limited sales of ZEJULA and VARUBY in Europe. For the years ended December 31, 2015 and 2016, product revenues consisted solely of VARUBI in the U.S. Total net product revenue was $5.2 million and $120.7 million for the years ended December 31, 2016 and 2017, respectively. These totals included $5.2 million and $11.9 million from sales of VARUBI/VARUBY, respectively, and zero and $108.8 million from sales of ZEJULA, respectively. The following table summarizes balances and activity in each of the product revenue allowance and reserve categories for the years ended December 31, 2015 (as revised), 2016 (as revised) and 2017 (in thousands): Chargebacks, Government Returns Total Balance at December 31, 2014 $ — $ — $ — $ — Provision related to current period sales 813 422 8 1,243 Adjustment related to prior period sales — — — — Credit or payments made during the period — — — — Balance at December 31, 2015 813 422 8 1,243 Provision related to current period sales 2,231 1,941 10 4,182 Adjustment related to prior period sales — — — — Credit or payments made during the period (2,867) (1,051) — (3,918) Balance at December 31, 2016 177 1,312 18 1,507 Provision related to current period sales 21,732 12,090 16,338 50,160 Adjustment related to prior period sales — 62 — 62 Credit or payments made during the period (19,821) (7,014) (6) (26,841) Balance at December 31, 2017 $ 2,088 $ 6,450 $ 16,350 $ 24,888 The provision for returns related to sales for the year ended December 31, 2017 was primarily related to VARUBI IV, due to the Company’s update to the VARUBI IV package insert in January 2018. License, Collaboration and Other Revenues The Company enters into out-licensing agreements that are within the scope of Topic 606, under which it licenses certain rights to its product candidates to third parties. The terms of these arrangements typically include payment to the Company of one or more of the following: non-refundable, up-front license fees; development, regulatory and commercial milestone payments; payments for manufacturing supply services the Company provides through its contract manufacturers; and royalties on net sales of licensed products. Each of these payments results in license, collaboration and other revenues, except for revenues from royalties on net sales of licensed products, which are classified as royalty revenues. In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under each of its agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must develop assumptions that require judgment to determine the stand-alone selling price for each performance obligation identified in the contract. The Company uses key assumptions to determine the stand-alone selling price, which may include forecasted revenues, development timelines, reimbursement rates for personnel costs, discount rates and probabilities of technical and regulatory success. Licenses of Intellectual Property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from non-refundable, up-front fees allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from non-refundable, up-front fees. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone Payments: At the inception of each arrangement that includes development milestone payments, the Company evaluates whether the milestones are considered probable of being reached and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The transaction price is then allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect license, collaboration and other revenues and earnings in the period of adjustment. Manufacturing Supply Services: Arrangements that include a promise for future supply of drug substance or drug product for either clinical development or commercial supply at the licensee’s discretion are generally considered as options. The Company assesses if these options provide a material right to the licensee and if so, they are accounted for as separate performance obligations. If the Company is entitled to additional payments when the licensee exercises these options, any additional payments are recorded in license, collaboration and other revenues when the licensee obtains control of the goods, which is upon delivery. Royalties: For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its out-licensing arrangements. The Company receives payments from its licensees based on billing schedules established in each contract. Up-front payments and fees are recorded as deferred revenue upon receipt or when due, and may require deferral of revenue recognition to a future period until the Company performs its obligations under these arrangements. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. The Company does not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between payment by the licensees and the transfer of the promised goods or services to the licensees will be one year or less. The following table presents changes in the Company’s contract assets and liabilities during the years ended December 31, 2016 (as revised) and 2017 (in thousands): Balance at Additions Deductions Balance at Year ended December 31, 2016 Contract assets $ 1,000 $ — $ — $ 1,000 Contract liabilities: Deferred revenue $ 92 $ 653 $ (345) $ 400 Year ended December 31, 2017 Contract assets $ 1,000 $ — $ — $ 1,000 Contract liabilities: Deferred revenue $ 400 $ — $ (94) $ 306 During the years ended December 31, 2015, 2016 and 2017, the Company recognized the following revenues as a result of changes in the contract asset and the contract liability balances in the respective periods (in thousands): Years Ended December 31, 2015 2016 2017 Revenue recognized in the period from: (as revised) (as revised) Amounts included in the contract liability at the beginning of the period $ — 93 $ 94 Performance obligations satisfied in previous periods $ — — $ —

License and Collaboration Arran

License and Collaboration Arrangements	12 Months Ended
	Dec. 31, 2017
License And Collaboration Agreements Abstract
License and Collaboration Arrangements	14. License and Collaboration Agreements Rolapitant In-License In December 2010, the Company entered into a license agreement with OPKO Health, Inc., or OPKO, to obtain an exclusive, royalty-bearing, sublicensable worldwide license to research, develop, manufacture, market and sell rolapitant. Under the OPKO license the Company is obligated to use commercially reasonable efforts to conduct all preclinical, clinical, regulatory and other activities necessary to develop and commercialize rolapitant. Under the terms of the OPKO license, the Company paid OPKO $6.0 million upon signing the agreement and issued to OPKO shares of its convertible preferred stock, then valued at $0.6 million, which shares have since been converted into common stock. The Company has also made all development milestone payments to OPKO, totaling $30.0 million, based on achieving specified regulatory milestones in the U.S. and Europe. In addition, the Company is required to make additional milestone payments to OPKO of up to an aggregate of $85.0 million if specified levels of annual net sales of rolapitant are achieved. The Company is required to pay OPKO tiered royalties on annual net sales of rolapitant achieved in the United States and Europe at percentage rates that range from the low teens to the low twenties, which the Company expects will result in an effective royalty rate in the low teens. The royalty rate on annual net sales outside of the United States and Europe is slightly above the single digits. Under certain circumstances, the Company is required to pay OPKO an annual minimum royalty of $2.5 million in each of the first five full calendar years of commercial sales of VARUBI/VARUBY. In any year during this period, in certain circumstances, if royalty payments amount to less than $2.5 million, the difference may be deemed a royalty shortfall and will be payable within 45 days of each calendar year end. Any such royalty shortfalls may be offset dollar for dollar against royalties due in future periods, for the first five calendar years of VARUBI sales. As of December 31, 2016, the Company had incurred $0.7 million of royalties based on its 2016 VARUBI net product revenues. As this amount was less than the $2.5 million annual minimum, the Company accrued an additional $1.8 million royalty obligation owed to OPKO as of December 31, 2016, which is capitalized in the ‘other assets’ caption on the consolidated balance sheet. The Company has concluded the royalty shortfall amount for the year ended December 31, 2016 will no longer be recoverable through future years’ sales, and wrote off $2.0 million as a component of cost of product sales in the year ended December 31, 2017. If the Company elects to develop and commercialize rolapitant in Japan through a third-party licensee the Company will share equally with OPKO all amounts received by it in connection with such activities under the Company’s agreement with such third party, subject to certain exceptions and deductions. The Company is responsible for all preclinical, clinical, regulatory and other activities necessary to develop and commercialize rolapitant. There were no ongoing clinical trials for rolapitant at the time of its acquisition. As of the date of acquisition, none of the assets acquired had alternative future uses, nor had they reached a stage of technological feasibility. As no processes or activities that would constitute a “business” were acquired along with the license, the transaction was accounted for as an asset acquisition by recording the entire purchase price of $6.6 million as acquired in-process research and development expense. As of December 31, 2017, the Company has made milestone payments to date totaling $30.0 million under this license agreement, $25.0 million of which has been capitalized as intangible assets on the consolidated balance sheet. Niraparib In-License In May 2012, the Company entered into a license agreement with Merck Sharp & Dohme Corp., a subsidiary of Merck, under which the Company obtained exclusive, worldwide rights to certain patents and non-exclusive rights to certain Merck know-how, to research, develop, manufacture, market and sell niraparib for all therapeutic and prophylactic uses in humans. Under the Merck license, the Company is obligated to use diligent efforts to develop and commercialize a licensed product. Under the terms of the license agreement, the Company made an up-front payment to Merck of $7.0 million in June 2012. The Company is also required to make milestone payments to Merck of up to an aggregate of $57.0 million in development and regulatory milestones for the first indication, up to an aggregate of $29.5 million in development and regulatory milestones for each successive indication, and up to $87.5 million in one-time sales milestones based on the achievement of annual sales objectives. The Company pays Merck tiered royalties at a percentage rate in the low teens based on worldwide annual net sales. As of the date of acquisition, none of the assets acquired had alternative future uses, nor had they reached a stage of technological feasibility. As no processes or activities that would constitute a “business” were acquired along with the license, the transaction has been accounted for as an asset acquisition and the entire purchase price of $7.0 million has been recorded as acquired in-process research and development expense. The Company has made milestone payments to date totaling $52.2 million, $40.0 million of which has been capitalized as intangible assets on the consolidated balance sheet. The Company paid $39.5 million of milestones during the year ended December 31, 2017. Immuno-Oncology Platform License In March 2014, the Company entered into a collaboration and exclusive license agreement with AnaptysBio, Inc., or AnaptysBio, a therapeutic antibody company. Under the terms of this agreement, the Company obtained an exclusive, royalty-bearing, sublicensable worldwide license to research, develop, manufacture, market and sell products based on AnaptysBio’s proprietary technology for the discovery, generation and optimization of certain specified immunotherapy antibodies. Specifically, the Company received exclusive rights to monospecific antibody product candidates targeting PD-1, TIM-3 and LAG-3, and certain bi-specific antibody product candidates. The Company and AnaptysBio entered into an amendment in November 2014 to add an additional bi-specific antibody product candidate to the agreement. Under the agreement, AnaptysBio was responsible for performing initial discovery and development of therapeutic antibodies against immune checkpoint proteins, with the goal of generating immunotherapy antibodies for use in the treatment of cancer. The Company is responsible for the performance and costs of all subsequent preclinical, clinical, regulatory, manufacturing and other activities necessary to develop and commercialize antibodies selected under each of four development programs and is obligated to use commercially reasonable efforts to research, develop or commercialize at least one product under each development program. The Company and AnaptysBio entered into another amendment in February 2016 to extend the term of the initial discovery period and the Company’s and AnaptysBio’s associated activities under the agreement. Under the terms of the agreement, the Company made up-front, non-creditable and non-refundable cash payments of $19.0 million to AnaptysBio in 2014. The Company was also required to reimburse AnaptysBio for specified costs incurred by AnaptysBio in its initial discovery and development activities covered by the agreement. These activities are now complete. Programs may be extended by mutual agreement of the parties, and the Company can terminate on a program-by-program basis by providing 90 days prior written notice, subject to a wind-down period during which the Company’s obligation to reimburse AnaptysBio for specified costs would continue. For each of the four development programs, the Company will be required to make milestone payments to AnaptysBio of up to an aggregate of $18.0 million if certain research and development milestone events are achieved, and up to an additional $90.0 million of milestone payments if certain U.S. and non-U.S. regulatory submissions and approvals occur in initial and subsequent indications. The Company will be required to pay AnaptysBio tiered single-digit royalties, on a product-by-product basis, on worldwide annual net sales, and additional commercial milestone payments if specified levels of annual net sales of a product are attained. The Company has made milestone payments to date totaling $21.0 million, including $10.0 million during the year ended December 31, 2017. As of the date of the license transaction, none of the assets acquired had alternative future uses, nor had they reached a stage of technological feasibility. As the processes or activities that were acquired along with the license do not constitute a “business,” the transaction has been accounted for as an asset acquisition. In addition, the Company has concluded that its reimbursements to AnaptysBio for the research services called for under the agreement are at fair value. As a result of these factors, the up-front payments totaling $19.0 million have been recorded as acquired in-process research and development expense, and no portion of the payments has been ascribed to the future services to be provided to the Company by AnaptysBio. For the year ended December 31, 2016, the Company recorded approximately $3.3 million of research and development expense and no amounts for the year ended December 31, 2017 associated with amounts due to AnaptysBio under the collaboration. Technology Licenses In October 2012, the Company entered into two license agreements with AstraZeneca UK Limited, having aggregate up-front payments of $0.4 million. These agreements provide the Company with the exclusive right to certain methods of treating patients with PARP inhibitors solely with respect to niraparib. Under certain circumstances, the Company may be required to make milestone and royalty payments to AstraZeneca UK Limited based on the achievement of certain development and regulatory milestone events with regard to niraparib, and on net sales of niraparib. The Company has made milestone payments to AstraZeneca totaling $1.5 million to date. Merck Collaboration In May 2015, the Company entered into a research agreement with Merck Sharp & Dohme B.V., a subsidiary of Merck, to perform a trial to evaluate the preliminary safety and efficacy of niraparib plus KEYTRUDA® (pembrolizumab) in patients with triple negative breast cancer and Out-Licenses Takeda Pharmaceutical Co., Ltd. On July 27, 2017, the Company entered into an exclusive license agreement, or the Takeda Agreement, with Millennium Pharmaceuticals, Inc., a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited , or Takeda. Pursuant to the Takeda Agreement, the Company granted Takeda licenses under certain patent rights and know-how relating to niraparib to develop and commercialize niraparib for the treatment of all tumor types in Japan, and all tumor types excluding prostate cancer in South Korea, Taiwan, Russia and Australia. In connection with the Takeda Agreement, the Company received a $100.0 million up-front payment and is eligible to receive additional payments of up to $140.0 million related to the achievement of certain clinical development and regulatory milestones as well as up to $100.0 million related to the achievement of additional sales milestones. The Company will also be eligible to receive tiered royalties from Takeda based on percentages of net product sales ranging from the high teens to low thirties. Takeda is responsible for conducting and funding all development and commercialization of niraparib in the licensed territories, including research, development, regulatory and commercialization activities. Unless earlier terminated, the Takeda Agreement will continue in effect until the date on which the royalty term and all payment obligations with respect to all products in all countries have expired. The Company identified the following performance obligations at the inception of the Takeda Agreement: (1) exclusive license with rights to develop and commercialize niraparib to Takeda in the licensed territories for the associated tumor types, and (2) initial supply to Takeda of certain materials for the manufacture of niraparib. In addition, the Company may also become responsible for manufacturing certain niraparib products for clinical and commercial supply and providing technical assistance related to the transfer of know-how, at Takeda’s option, for the manufacture of niraparib for which the Company will receive reimbursement that approximates stand-alone selling prices. The Company evaluated the Takeda Agreement under Topic 606. Based on that evaluation, the up-front, non-refundable fees and the reimbursement received for the initial supply of materials constituted the amount of the consideration to be included in the transaction price and have been allocated to the performance obligations identified based on the Company’s best estimate of the relative stand-alone selling price. None of the clinical or regulatory milestones has been included in the transaction price, as all milestone amounts were fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including that receipt of the milestones is outside the control of the Company and contingent upon success in future clinical trials and the licensee’s efforts. Any consideration related to sales-based milestones (including royalties) will be recognized when the related sales occur as these amounts have been determined to relate predominantly to the license granted to Takeda and therefore are recognized at the later of when the performance obligation is satisfied or the related sales occur. The Company considered Takeda’s right to sublicense and manufacture certain niraparib products, and the fact that the manufacturing services are not proprietary and can be provided by other vendors, to conclude that the license has stand-alone functionality and is distinct. The Company believes that a change in the assumptions used to determine its stand-alone selling price for the license most likely would not have a significant effect on the allocation of consideration received (or receivable) to the performance obligations. The Company will re-evaluate the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur. During the year ended December 31, 2017, the Company allocated $100.0 million of the transaction price to the license and recognized this amount as revenue concurrent with the transfer of the license. Revenue associated with the initial supply of niraparib materials will be recognized when delivered to Takeda. Under the Takeda Agreement, for the year ended December 31, 2017, the Company recognized $100.0 million within license, collaboration and other revenues in its consolidated statements of operations and comprehensive loss. Janssen Biotech, Inc. On April 5, 2016, the Company entered into separate transactions with Janssen Biotech, Inc., or Janssen, and its affiliate, Johnson & Johnson Innovation – JJDC, Inc., or JJDC, consisting of a collaboration and license agreement with Janssen, or the Collaboration Agreement, and a stock purchase agreement and investor agreement, each with JJDC (the “Stock Purchase Agreement” and the “Investor Agreement,” respectively, and collectively with the Collaboration Agreement, the “Agreements”). Under the terms of the Collaboration Agreement, the Company granted Janssen licenses under certain patent rights and know-how relating to niraparib for prostate cancer worldwide, except for Japan. Janssen will conduct all development and commercialization of niraparib in the field of prostate cancer worldwide (excluding Japan). Pursuant to the Collaboration Agreement, within 30 days after the date of the Collaboration Agreement, the Company provided Janssen with electronic copies of certain know-how relating to development of niraparib. In addition, at Janssen’s request and in return for certain reimbursement, the Company is also responsible for manufacturing and supplying to Janssen all of Janssen’s requirements of active pharmaceutical ingredient, or API, for niraparib and niraparib products to be used by Janssen for its development activities in prostate cancer indications. Also at Janssen’s request, the Company is responsible for manufacturing of certain niraparib products and API for commercial sale in the field of prostate cancer. In both cases, if Janssen exercises its right to receive the manufacturing services, the Company will receive reimbursement that will at least cover its cost of providing such services. The Company received a $35.0 million up-front, non-refundable license fee from Janssen. Assuming successful development and commercialization of niraparib products for prostate cancer, the Company could receive up to an additional $43.0 million in clinical milestones and $372.0 million in regulatory and sales milestones as well as tiered, double-digit royalties on aggregate net sales of products in the field of prostate cancer. Janssen is responsible for funding all development and commercialization of niraparib in prostate cancer worldwide (excluding Japan), including research, development, manufacturing, regulatory and commercialization activities. Janssen may terminate the Collaboration Agreement at any time after April 5, 2017 upon 90 days’ written notice, upon termination of the Company’s license agreement with Merck or in the event of certain safety concerns. Either party may terminate the Collaboration Agreement for uncured material breach or bankruptcy. Unless earlier terminated, the Collaboration Agreement will continue in effect until the date on which the royalty term and all payment obligations with respect to all products in all countries have expired. The Company assessed this arrangement in accordance with Topic 606 and concluded that the contract counterparty, Janssen, is a customer. The Company identified the following material promises under the contract: (1) the licenses under certain patent rights relating to niraparib for prostate cancer worldwide, except for Japan, and transfer of certain development and regulatory information; and (2) the obligation to participate in Joint Committees. In addition, the Company identified the following customer options that will create manufacturing obligations for the Company upon exercise by Janssen: (1) the supply of API and niraparib products for Janssen’s development and commercial needs; and (2) the supply of niraparib for Janssen’s clinical trial needs. The Company considered the manufacturing capabilities of Janssen, Janssen’s right to sublicense and manufacture API, and the fact that the manufacturing services are not proprietary and can be provided by other vendors, to conclude that the license has stand-alone functionality and is distinct. The Company’s obligation to participate in the Joint Committees and provide development, regulatory and commercialization information to Janssen does not significantly impact or modify the licenses’ granted functionality. Further, the customer options for manufacturing services were evaluated as a material right, but were concluded to be immaterial to the Company’s financial statements. Based on these assessments, the Company identified the license and the participation in Joint Committees as the only performance obligations at the inception the arrangement, which were both deemed to be distinct. Under the Collaboration Agreement, in order to evaluate the appropriate transaction price, the Company determined that the up-front amount constituted the entirety of the consideration to be included in the transaction price and to be allocated to the performance obligations based on the Company’s best estimate of their relative stand-alone selling prices. For the license, the stand-alone selling price was calculated using an income approach model and included the following key assumptions: the development timeline, revenue forecast, discount rate and probabilities of technical and regulatory success. The relative selling price of the Company’s Joint Committee participation was based on a full-time equivalent rate for the level of effort required, which can be reasonably estimated to be incurred over the performance period, which is the development period. The Company believes that a change in the assumptions used to determine its stand-alone selling price for the license most likely would not have a significant effect on the allocation of consideration received (or receivable) to the performance obligations. At execution, the transaction price included only the $35.0 million up-front consideration received. None of the clinical or regulatory milestones has been included in the transaction price, as all milestone amounts were fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including that receipt of the milestones is outside the control of the Company and contingent upon success in future clinical trials and the licensee’s efforts. Any consideration related to sales-based milestones (including royalties) will be recognized when the related sales occur as they were determined to relate predominantly to the license granted to Janssen and therefore have also been excluded from the transaction price. The Company will re-evaluate the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur. During the second quarter of 2016, the Company allocated $34.5 million (as revised) of the transaction price to the license and recognized this amount as revenue concurrent with the transfer of the license and certain development and regulatory know-how that occurred within 30 days of entering into the Collaboration Agreement. Revenue allocated to the Joint Committees performance obligation, $0.5 million, is being recognized on a straight-line basis over a period of five years, which, in management’s judgment, is the best measure of progress toward satisfying the performance obligation and represents the Company’s best estimate of the period of the obligation to participate in the Joint Committees. Through December 31, 2017, the Company had recognized $34.7 million as license and collaboration revenue under the Collaboration Agreement. The remaining transaction price of $0.3 million is recorded in deferred revenue as of December 31, 2017 on the consolidated balance sheets and will be recognized as revenue over the remaining period of 39 months. Revenue associated with the manufacturing supply services is recognized when the material is delivered to Janssen. For the years ended December 31, 2016 and 2017, the Company recognized $1.8 million (as revised) and $2.5 million, respectively, as other revenues within license, collaboration and other revenues in the Company’s consolidated statements of operations and comprehensive loss under the Collaboration Agreement. Additionally, the Company considered whether the Stock Purchase Agreement and the Investor Agreement with JJDC would be subject to combination with the Collaboration Agreement. The Company determined that they should not be combined because the deliverables and terms in these arrangements are not closely interrelated or interdependent in terms of payment or functionality, the arrangements were negotiated separately, and the common stock was sold at approximately its fair value. Zai Lab (Shanghai) Co., Ltd. On September 28, 2016, the Company entered into a Collaboration, Development and License Agreement, or the Zai Agreement, with Zai Lab. Under the terms of the Zai Agreement, the Company exclusively licensed the rights to develop and commercialize niraparib to Zai Lab for the China Territories. Zai Lab will conduct all development and commercialization of niraparib in the China Territories, except for prostate cancer. Under the terms of the Zai Agreement, the Company received a $15.0 million up-front, non-refundable license fee from Zai Lab in the fourth quarter of 2016. Assuming successful development and commercialization of niraparib products in the China Territories, the Company could receive additional regulatory and sales milestones as well as tiered, double-digit royalties on aggregate net sales of products in the China Territories. Zai Lab is responsible for funding all development and commercialization of niraparib in the China Territories, including research, development, manufacturing, regulatory and commercialization activities. The term of the Zai Agreement continues, on a country-by-country basis, until the later of expiration of the last patent in the China Territories covering the niraparib product, or ten years from the first commercial sale in such country. The Zai Agreement may also be terminated by Zai Lab at any time upon prior written notice, or by either party for material breach or insolvency. The Company identified the following performance obligations under the contract: (1) exclusive license with rights to develop and commercialize niraparib to Zai Lab for the China Territories; (2) provision of technical assistance related to the know-how transfer for the development of niraparib; and (3) initial supply to Zai Lab of certain materials for the manufacture of niraparib. In addition, the Company may also become responsible for manufacturing of certain niraparib products and materials for commercial sale in certain instances based on regulatory requirements in the China Territories for which the Company will receive reimbursement that approximates stand-alone selling price. The Zai Agreement also provided the Company with an option to co-market niraparib in the China Territories with Zai Lab, in return for certain consideration. In February 2018, the Company and Zai Lab entered into an amendment to the Zai Agreement, eliminating the Company’s co-marketing right. In addition, the Zai Agreement provides the Company with a right of first refusal with respect to licenses for two novel, discovery-stage immuno-oncology programs from Zai Lab. The Company evaluated the Zai Agreement under Topic 606. Based on that evaluation, the up-front, non-refundable fees and the reimbursement received for the initial supply of materials constituted the amount of the consideration to be included in the transaction price and have been allocated to the performance obligations identified based on the Company’s best estimate of the relative stand-alone selling price. None of the clinical or regulatory development milestones have been included in the transaction price, as all such milestone amounts are not within the control of the Company or the licensee and are not considered probable to occur until those approvals are received. Any consideration related to sales-based milestones (including royalties) will be recognized when the related sales occur as these amounts have been determined to relate predominantly to the license granted to Zai Lab and therefore are recognized at the later of when the performance obligation is satisfied or the related sales occur. The Company concluded the option to co-market niraparib was not a repurchase right as Zai Lab would continue to control its rights to commercialize niraparib in its licensed territories if the Company exercised its right. The Company further assessed and concluded that the probability of exercise of this right is remote, and the transaction price received and described above was properly allocated to the performance obligations under this agreement and recognized to revenue as those performance obligations were satisfied by the Company. The Company will re-evaluate the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur. The amendment described above, eliminating the co-marketing right, had no impact on the Company’s accounting conclusions under Topic 606. During the third quarter of 2016, the Company allocated $14.8 million (as revised) of the transaction price to the license and recognized this amount as revenue concurrent with the transfer of the license. Revenue allocated to the technical assistance performance obligation, $0.2 million (as revised), was recognized on a straight-line basis through the service period which was substantially completed during the fourth quarter of 2016. In addition, $0.7 million (as revised) of revenue associated with the initial manufacturing supply services was recognized upon delivery of the materials during the fourth quarter of 2016. No revenues were recognized under the Zai Agreement during the year ended December 31, 2017. Jiangsu Hengrui Medicine Co., Ltd. In July 2015, the Company entered into a license agreement with Jiangsu Hengrui Medicine Co., Ltd., or Hengrui, pursuant to which Hengrui has licensed the rights to develop, manufacture and commercialize rolapitant in the China Territories. The Company received a $1.0 million up-front, non-refundable license fee from Hengrui in the fourth quarter of 2015. The Company has evaluated the terms of this arrangement under Topic 606 and has determined that there are two performance obligations: (1) exclusive license with rights to develop, manufacture and commercialize rolapitant in the China Territories; and (2) provision of technical assistance related to the know-how transfer for the development of the rolapitant formulations. The Company further determined that the transaction price for this arrangement includes the $1.0 million up-front consideration received and a future regulatory development milestone of $1.0 million. This future milestone payment relates to the submission of the clinical trial application with the China Food and Drug Administration, or the China FDA. The Company is also entitled to an additional payment of $1.0 million contingent on the achievement of regulatory approval from the China FDA. However, as this milestone is not within the control of the Company or Hengrui, the amount has not been included in the transaction price by the Company. Any consideration related to sales-based milestones (including royalties at percentage rates in the low teens) will be recognized when the related sales occur as these amounts have been determined to relate predominantly to the license granted to Hengrui. The Company will re-evaluate the transaction price in each reporting period and as uncertain events are resolved or other changes in circumstances occur. During the third quarter of 2015, the Company allocated $1.9 million (as revised) of the transaction price to the license and recognized this amount as revenue concurrent with the transfer of the license. Revenue allocated to the technical assistance performance obligation, $0.1 million (as revised), was recognized on a straight-line basis through the service period and was substantially completed during the fourth quarter of 2016. No revenues were recognized under this agreement during the year ended December 31, 2017.

Segment Information

Segment Information	12 Months Ended
	Dec. 31, 2017
Segment Information
Segment Information	15. Segment Information Revenues by Product Product revenues, net consisted of the following (in thousands): Years Ended December 31, 2015 2016 2017 (as revised) (as revised) ZEJULA $ — $ — $ 108,756 VARUBI/VARUBY 2,026 5,174 11,944 Total product revenues, net $ 2,026 $ 5,174 $ 120,700 Revenues by Geographic Location Net product revenues are attributed to countries based on the location of the customer. License, collaboration and other revenues are attributed to the operations of the Company in the United States. Royalty revenues are attributed to countries based on the location of the collaborator. The following table presents total revenues by geography (in thousands): Years Ended December 31, 2015 2016 2017 (as revised) (as revised) United States $ 4,038 $ 58,018 $ 221,955 Europe — — 1,371 Total revenues $ 4,038 $ 58,018 $ 223,326 Significant Customers Revenues and accounts receivable from each of the Company’s customers who individually accounted for 10% or more of total revenues and/or 10% or more of accounts receivable consisted of the following (* indicates less than 10%): Percent of Total Revenues Percent of Accounts Receivable Years Ended December 31, December 31, 2016 2017 2016 2017 (as revised) (as revised) Janssen Biotech, Inc. 63 % * % 26 % * % Zai Lab (Shanghai) Co., Ltd. 27 % * % 11 % * % Takeda Pharmaceutical Co., Ltd. * % 45 % * % * % Jiangsu Hengrui Medicine Co., Ltd. * % * % 10 % * % Distributor "A" * % 32 % 42 % 31 % Distributor "B" * % 11 % * % 49 % Property and Equipment, Net by Location Property and equipment, net by location consisted of the following (in thousands): December 31, 2016 2017 United States $ 6,194 $ 8,583 Switzerland 446 669 Germany — 119 Spain — 281 Total property and equipment, net $ 6,640 $ 9,652

Consolidated Quarterly Financia

Consolidated Quarterly Financial Data - Unaudited	12 Months Ended
	Dec. 31, 2017
Consolidated Quarterly Financial Data - Unaudited
Consolidated Quarterly Financial Data - Unaudited	16. Consolidated Quarterly Financial Data - Unaudited The following table presents unaudited consolidated quarterly financial data for the years ended December 31, 2016 and 2017 (in thousands, except per share data): Three Months Ended March 31, June 30, September 30, December 31, March 31, June 30, September 30, December 31, 2016 2016 2016 2016 2017 2017 2017 2017 (a)(b) (b) (b) (b) Revenues: Product revenue, net $ 276 $ 1,242 $ 1,326 $ 2,330 $ 2,139 $ 28,829 $ 41,755 $ 47,977 License, collaboration and other revenues 24 34,568 (d) 15,661 (e) 2,591 934 635 101,011 (f) 46 Total revenues 300 35,810 16,987 4,921 3,073 29,464 142,766 48,023 Expenses: Cost of sales - product 79 234 378 512 444 3,620 6,216 30,857 (g) Cost of sales - intangible asset amortization 464 463 464 490 2,979 1,254 1,435 Research and development 52,709 50,138 60,783 71,514 66,122 71,400 73,388 97,832 Selling, general and administrative 30,149 36,218 37,685 54,526 69,262 92,979 83,998 90,569 Acquired in-process research and development (c) 4,000 4,000 1,940 9,000 — 7,000 — 3,000 Total expenses 87,401 91,053 101,250 136,016 136,318 177,978 164,856 223,693 Loss from operations (87,101) (55,243) (84,263) (131,095) (133,245) (148,514) (22,090) (175,670) Interest expense (3,981) (4,120) (4,119) (4,267) (4,267) (4,426) (4,424) (6,641) Interest income 102 209 532 597 841 959 1,133 1,214 Other income — — — — — — 243 85 Loss before income taxes (90,980) (59,154) (87,850) (134,765) (136,671) (151,981) (25,138) (181,012) Provision for income taxes — — — 1,475 54 78 139 1,053 Net loss $ (90,980) $ (59,154) $ (87,850) $ (136,240) $ (136,725) $ (152,059) $ (25,277) $ (182,065) Net loss per share - basic and diluted $ (2.22) $ (1.29) $ (1.72) $ (2.59) $ (2.55) $ (2.82) $ (0.47) $ (3.35) Weighted-average shares - basic and diluted 40,966 45,808 51,151 52,589 53,685 53,982 54,241 54,403 (a) Amounts for the quarter ended March 31, 2016 have been retroactively adjusted to reflect an increase in research and development costs and selling, general and administrative costs in the amount of $0.1 million and $0.1 million, respectively, as a result of the adoption of ASU 2016-09. (b) Amounts for each of the quarterly periods for the year ended December 31, 2016 have been revised to reflect the Company’s adoption of ASU No. 2014-09 effective January 1, 2017, with full retrospective application. This ASU amends the guidance for accounting for revenue from contracts with customers. (c) Acquired in-process research and development expenses relate to licensing agreement milestone expenses for the following periods: (i) $4.0 million to AnaptysBio for the quarter ended March 31, 2016; (ii) $4.0 million to AnaptysBio for the quarter ended June 30, 2016; (iii) $1.0 million to AnaptysBio and $0.9 million to Merck for the quarter ended September 30, 2016; (iv) $9.0 million to Merck for the quarter ended December 31, 2016; (v) $7.0 million to AnaptysBio for the quarter ended June 30, 2017; and (vi) $3.0 million to AnaptysBio for the quarter ended December 31, 2017. (d) In the quarter ended June 30, 2016, the Company received $35.0 million and transferred the license and related know-how required under its collaboration agreement with Janssen. $34.6 million of related license revenue was recognized during the quarter. (e) In the quarter ended September 30, 2016, the Company received $15.0 million and transferred the license and related know-how required under its collaboration agreement with Zai Lab. $14.8 million of related license revenue was recognized during the quarter. (f) In the quarter ended September 30, 2017, the Company received $100.0 million and transferred certain patent rights and know-how relating to niraparib to Takeda. The entire amount of related license revenue was recognized during the quarter. (g) Product cost of sales for the quarter ended December 31, 2017 includes a $16.7 million lower of cost or market write-down of VARUBI inventories and a $1.6 million loss on firm purchase commitments.

Subsequent Event

Subsequent Event	12 Months Ended
	Dec. 31, 2017
Subsequent Events.
Subsequent Events	17. Subsequent Events In January 2018, after post-marketing reports of side effects experienced following the commercial introduction of VARUBI IV, the Company updated the VARUBI IV package insert, including modifications to the contraindications, warnings and precautions, and adverse reactions sections. In February 2018, the Company determined that it would cease marketing and distribution of VARUBI IV and pursue strategic alternatives for the VARUBI brand, including potentially out-licensing the VARUBI product line.

Schedule II - Valuation and Qau

Schedule II - Valuation and Qaulifying Accounts and Reserves	12 Months Ended
	Dec. 31, 2017
Consolidated Quarterly Financial Data - Unaudited
Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	Schedule II — Valuation and Qualifying Accounts and Reserves Years Ended December 31, 2015, 2016 and 2017 (in thousands) Balance at Charges to Credits or Balance at Product Sales Allowances Year ended December 31, 2015 (as revised) $ — $ $ — $ Year ended December 31, 2016 (as revised) $ $ $ (3,918) $ Year ended December 31, 2017 $ $ $ (26,835) $ Allowance for Product Returns Year ended December 31, 2015 (as revised) $ — $ $ — $ Year ended December 31, 2016 (as revised) $ $ $ — $ Year ended December 31, 2017 $ $ $ (6) $ 16,350

Basis of Presentation and Signi

Basis of Presentation and Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Basis of Presentation and Significant Accounting Policies
Basis of Presentation	Basis of Presentation The Company’s consolidated financial statements reflect the operations of the Company and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. The consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States, or GAAP. See “ New Accounting Pronouncements - Recently Adopted ” below for a discussion of certain revisions to prior period financial statements made in connection with the Company’s adoption of new revenue recognition guidance retroactive to January 1, 2015.
Segment Information	Segment 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 segment, which is the business of developing and commercializing safer and more effective oncology-focused therapeutics.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, other comprehensive loss and the related disclosures. Significant estimates in these consolidated financial statements include estimates made in connection with accrued research and development expenses, stock-based compensation expense, revenue, valuation of convertible notes, inventory, intangible assets and related amortization. The Company bases its estimates on historical experience, known trends and other market-specific or other relevant factors that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions.
Concentrations of Credit Risk and Off-Balance Sheet Risk	Concentrations of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to concentrations of credit risk are primarily cash and cash equivalents. The Company maintains its cash and cash equivalent balances primarily in the form of money market fund accounts with financial institutions that management believes are creditworthy. The Company’s investment policy includes guidelines on the quality of the institutions and financial instruments and defines allowable investments that the Company believes minimizes the exposure to concentration of credit risk. The Company has no financial instruments with off-balance-sheet risk of loss. The Company also is subject to credit risk from its accounts receivable related to its product sales, collaborators and licenses. As part of its credit management policy, the Company performs ongoing credit evaluations of its customers, and the Company has not required collateral from any customer. The Company has not recorded any allowances for doubtful accounts at either December 31, 2016 or 2017.
Foreign Currency	Foreign Currency A subsidiary’s functional currency is the currency of the primary economic environment in which the subsidiary operates; normally, that is the currency of the environment in which a subsidiary primarily generates and expends cash. In making the determination of the appropriate functional currency for a subsidiary, the Company considers cash flow indicators, local market indicators, financing indicators and the subsidiary’s relationship with both the parent company and other subsidiaries. For subsidiaries that are primarily a direct and integral component or extension of the parent entity’s operations, the U.S. dollar is the functional currency. For each foreign subsidiary with a functional currency other than the U.S. dollar, assets and liabilities are translated at current exchange rates at the balance sheet date. Revenue and expense items are translated at average foreign exchange rates for the period. Adjustments resulting from the translation of the financial statements of these subsidiaries into U.S. dollars are excluded from the determination of net loss and are recorded in accumulated other comprehensive loss, a separate component of stockholders’ equity. For foreign subsidiaries with the U.S. dollar as the functional currency, monetary assets and liabilities are re-measured into U.S. dollars at the current exchange rate on the balance sheet date. Nonmonetary assets and liabilities are re-measured into U.S. dollars at historical exchange rates. Revenue and expense items are translated at average exchange rates prevailing during each period. Consolidated realized and unrealized foreign currency transaction gains and losses are recorded in selling, general and administrative expenses in the consolidated statements of operations and comprehensive loss. Consolidated realized and unrealized foreign currency transaction losses were negligible for the year ended December 31, 2015, and were $0.2 million and $0.5 million for the years ended December 31, 2016 and 2017, respectively.
Revenue Recognition	Revenue Recognition Effective January 1, 2017, the Company adopted Accounting Standards Codification, or ASC, Topic 606, Revenue from Contracts with Customers , using the full retrospective transition method. Under this method, the Company has revised its consolidated financial statements for the years ended December 31, 2015 and 2016, and applicable interim periods within those years, as if Topic 606 had been effective for those periods. This standard applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. Under Topic 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. For a complete discussion of accounting for net product revenue and license, collaboration and other revenues, see Note 13, “ Revenue Recognition ”.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly-liquid investments with original or remaining maturity from the date of purchase of three months or less to be cash equivalents. Cash and cash equivalents include bank demand deposits and money market funds that invest primarily in certificates of deposit, commercial paper and U.S. government and U.S. government agency obligations. Cash equivalents are reported at fair value.
Restricted Cash	Restricted Cash Restricted cash consists of cash balances held as collateral for the Company’s employee credit card programs.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. The fair value hierarchy prioritizes valuation inputs based on the observable nature of those inputs. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of investment credit quality. The hierarchy defines three levels of valuation inputs: Level 1 inputs Quoted prices in active markets for identical assets or liabilities Level 2 inputs Observable inputs other than Level 1 inputs, including quoted prices in active markets for similar assets or liabilities and quoted prices for identical assets or liabilities in markets that are not active Level 3 inputs Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability The following table presents information about the Company’s financial assets and liabilities that have been measured at fair value at December 31, 2016 and 2017 and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands): December 31, 2016 Description Balance Sheet Classification Total Level 1 Level 2 Level 3 Assets: Money market funds Cash and cash equivalents $ 766,186 $ 766,186 $ — $ — Total assets $ 766,186 $ 766,186 $ — $ — December 31, 2017 Description Balance Sheet Classification Total Level 1 Level 2 Level 3 Assets: Money market funds Cash and cash equivalents $ 593,955 $ 593,955 $ — $ — Total assets $ 593,955 $ 593,955 $ — $ — The carrying amounts of accounts payable and accrued expenses approximate their fair values due to their short-term maturities. In September 2014, the Company issued $201.3 million aggregate principal amount of 3.00% convertible senior notes due October 1, 2021, or the Convertible Notes. Interest is payable semi-annually in arrears on April 1 and October 1 of each year, beginning on April 1, 2015. As of December 31, 2017, the carrying value of the Convertible Notes was $143.4 million, net of unamortized discount and debt issuance costs and the fair value of the principal amount was $499.1 million. As of December 31, 2017, the carrying value of the Company’s borrowing under its term loan agreement approximated its fair value, considering the short period of time since the December 6, 2017 borrowing date. The Convertible Notes and the term loan agreement are discussed in more detail in Note 7, “ Debt. ”
Property and Equipment	Property and Equipment Property and equipment are stated at cost, less accumulated depreciation. Property and equipment are depreciated using the straight-line method over the estimated useful lives of the assets. Leasehold improvements are amortized over the economic life of the asset or the remaining lease term, whichever is shorter. Maintenance and repairs are expensed as incurred. The following estimated useful lives were used to depreciate the Company’s assets: Estimated Useful Life Furniture and fixtures years Computer equipment and software years Manufacturing equipment years Leasehold improvements Shorter of the useful life or the remaining lease term Upon retirement or sale, the cost of the disposed asset and the related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized in income. The Company reviews long-lived assets when events or changes in circumstances indicate the carrying value of the assets may not be recoverable. Recoverability is measured by comparison of an asset’s book value to the estimated undiscounted future net cash flows that the asset is expected to generate. If the estimated future undiscounted net cash flows are less than the book value, the asset is considered to be impaired, and the impairment loss to be recognized in income is measured as the amount by which the book value of the asset exceeds its fair value, which is measured based on the estimated discounted future net cash flows that the asset is expected to generate.
Research and Development Expenses	Research and Development Expenses Research and development costs are charged to expense as incurred and include: · employee-related expenses, including salaries, bonuses, benefits, travel and stock-based compensation expense; · fees and expenses incurred under agreements with contract research organizations, investigative sites, research consortia and other entities in connection with the conduct of clinical trials and preclinical studies and related services, such as administrative, data management, laboratory and biostatistics services; · the cost of acquiring, developing and manufacturing active pharmaceutical ingredients for product candidates that have not received regulatory approval, clinical trial materials and other research and development materials; · fees and costs related to regulatory filings and activities; · pre-commercial license fees and milestone payments related to the acquisition of in-licensed product candidates, which are reported on the statements of operations as acquired in-process research and development; · facilities, depreciation and other expenses, which include direct and allocated expenses for rent, utilities, maintenance of facilities, insurance and other supplies; and · other costs associated with clinical, preclinical, discovery and other research activities. Costs for certain development activities, such as clinical trials and manufacturing development activities, are recognized based on an evaluation of the progress to completion of specific tasks using data such as patient enrollment, clinical site activations, and information provided to the Company by its vendors on their actual costs incurred or level of effort expended. Payments for these activities are based on the terms of the individual arrangements, which may differ from the pattern of costs incurred, and are reflected on the consolidated balance sheets as prepaid or accrued research and development expenses. Certain clinical development costs incurred by the Company with respect to its niraparib program are reimbursed as part of a collaborative research agreement with Merck Sharp & Dohme B.V., a subsidiary of Merck & Co., Inc., or Merck. Cost-sharing amounts received by the Company are recorded as a reduction to research and development expenses.
Acquired In-Process Research and Development Expense	Acquired In-Process Research and Development Expense The Company has acquired the rights to develop and commercialize new product candidates. Up-front payments that relate to the acquisition of a new drug compound, as well as pre-commercial milestone payments, are immediately expensed as acquired in-process research and development in the period in which they are incurred, provided that the new drug compound did not also include processes or activities that would constitute a “business” as defined under GAAP, the drug has not achieved regulatory approval for marketing and, absent obtaining such approval, has no established alternative future use. Milestone payments made to third parties subsequent to regulatory approval are capitalized as intangible assets and amortized over the estimated remaining useful life of the related product. Royalties owed on sales of the products licensed pursuant to the agreements are expensed in the period the related revenues are recognized.
Advertising Expenses	Advertising Expenses The costs of advertising are expensed as incurred and included in selling, general, and administrative expenses in the consolidated statements of operations and comprehensive loss. For the years ended December 31, 2015, 2016 and 2017, advertising expenses totaled $3.6 million, $9.2 million, and $21.1 million, respectively.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Comprehensive loss consists of net loss and other comprehensive loss. Other comprehensive loss includes foreign currency translation adjustments and unrealized gains and losses on pension obligations. The following table presents changes in the components of accumulated other comprehensive loss (in thousands): Foreign currency translation adjustments Unrealized loss on pension liability Total Balance at December 31, 2015 $ — $ — $ — Other comprehensive (loss) income (142) (2,782) (2,924) Balance at December 31, 2016 (142) (2,782) (2,924) Other comprehensive (loss) income 401 (3,359) (2,958) Balance at December 31, 2017 $ 259 $ (6,141) $ (5,882)
Income Taxes	Income Taxes The Company accounts for income taxes in accordance with ASC Topic 740, Accounting for Income Taxes , which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. The Company determines its deferred tax assets and liabilities based on differences between financial reporting and tax bases of assets and liabilities, which are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. On December 22, 2017, the Tax Cuts and Jobs Act of 2017 was signed into law, resulting in significant changes to the U.S. corporate income tax system. For additional details regarding this act, see Note 10, “ Income Taxes ”.
Stock-Based Compensation Expense	Stock-Based Compensation Expense Stock-based compensation is recognized as expense for each stock-based award based on its estimated fair value. The Company determines the fair value of each stock option award at its grant date using the Black-Scholes option pricing model. The Company determines the fair value of each restricted stock unit, or RSU, at its grant date based on the closing market price of the Company’s common stock on that date. The value of the award is recognized as expense on a straight-line basis over the requisite service period and is adjusted for pre-vesting forfeitures in the period in which the forfeitures occur. For stock awards that have a performance condition, the Company recognizes compensation expense based on its assessment of the probability that the performance condition will be achieved, using an accelerated attribution model, over the explicit or implicit service period.
Inventory	Inventory Inventories are stated at the lower of cost or estimated net realizable value, on a first-in, first-out, or FIFO, basis. Prior to the regulatory approval of its product candidates, the Company incurs expenses for the manufacture of drug product that could potentially be available to support the commercial launch of its products. Until the first reporting period when regulatory approval has been received or is otherwise considered probable, the Company records all such costs as research and development expense. Inventory used in clinical trials is also expensed as research and development expense, when selected for such use. The Company performs an assessment of the recoverability of capitalized inventory during each reporting period, and writes down any excess and obsolete inventory to its net realizable value in the period in which the impairment is first identified. Such impairment charges, should they occur, are recorded as a component of cost of product sales in the consolidated statements of operations and comprehensive loss. The determination of whether inventory costs will be realizable requires the use of estimates by management. If actual market conditions are less favorable than projected by management, additional write-downs of inventory may be required.
Intangible Assets	Intangible Assets The Company maintains definite-lived intangible assets related to milestone payments made to third parties subsequent to regulatory approval for acquired and in-licensed product candidates. These assets are amortized over their remaining useful lives, which are generally estimated to be the remaining patent life. If the Company’s estimate of the product’s useful life is shorter than the remaining patent life, then the shorter period is used. Intangible assets are amortized using the economic consumption method if anticipated future revenues can be reasonably estimated. The straight-line method is used when future revenues cannot be reasonably estimated, with a cumulative catch-up of amortization expense for milestone payments that do not result in additional intellectual property rights and/or incremental cash flows. Amortization expense is recorded as a component of cost of sales in the consolidated statements of operations and comprehensive loss. The Company assesses its intangible assets for impairment if indicators are present or changes in circumstance suggest that impairment may exist. Events that could result in an impairment, or trigger an interim impairment assessment, include the receipt of additional clinical or nonclinical data regarding one of the Company’s drug candidates or a potentially competitive drug candidate, changes in the clinical development program for a drug candidate, or new information regarding potential sales for the drug. If impairment indicators are present or changes in circumstance suggest that impairment may exist, the Company performs a recoverability test by comparing the sum of the estimated undiscounted cash flows of each intangible asset to its carrying value on the consolidated balance sheet. If the undiscounted cash flows used in the recoverability test are less than the carrying value, the Company would determine the fair value of the intangible asset and recognize an impairment loss if the carrying value of the intangible asset exceeds its fair value.
Net Loss Per Share	Net Loss Per Share Basic and diluted net loss per common share is calculated by dividing net loss applicable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration of common stock equivalents. The Company’s potentially dilutive shares, which include outstanding stock options, Employee Stock Purchase Plan awards, unvested RSUs, and shares issuable upon conversion of the Convertible Notes, are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. The following table presents amounts that were excluded from the calculation of diluted net loss per share, due to their anti-dilutive effect (in thousands): Years Ended December 31, 2015 2016 2017 Outstanding stock options 5,878 6,979 6,908 Unvested restricted stock units 60 760 1,159 Shares issuable upon conversion of Convertible Notes 492 3,765 2,695 6,430 11,504 10,762 In September 2014, the Company issued Convertible Notes, which provide in certain situations for the conversion of the outstanding principal amount of the Convertible Notes into shares of the Company’s common stock at a predefined conversion rate. See Note 7, “ Debt ”, for additional information. In conjunction with the issuance of the Convertible Notes, the Company entered into capped call option transactions, or Capped Calls, with certain counterparties. The Capped Calls are expected generally to reduce the potential dilution, and/or offset, to an extent, the cash payments the Company may choose to make in excess of the principal amount, upon conversion of the Convertible Notes. As provided by the terms of the indenture underlying the Convertible Notes, the Company has a choice to settle the conversion obligation for the Convertible Notes in cash, shares or any combination of the two. The Company currently intends to settle the par value of the Convertible Notes in cash and any excess conversion premium in shares. Accordingly, the par value of the Convertible Notes will not be included in the calculation of diluted income per share, but the dilutive effect of the conversion premium will be considered in the calculation of diluted net income per share using the treasury stock method. The Convertible Notes were convertible as of December 31, 2015, 2016 and 2017. The share figures in the table above represent the estimated incremental shares that would be issued, after the consideration of the Capped Calls, assuming conversion of all of the outstanding Convertible Notes as of the respective balance sheet date.

Basis of Presentation and Sig27

Basis of Presentation and Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Basis of Presentation and Significant Accounting Policies
Schedule of company's financial assets and liabilities that have been measured at fair value and indicating the fair value hierarchy of the valuation inputs utilized to determine such fair value:	The following table presents information about the Company’s financial assets and liabilities that have been measured at fair value at December 31, 2016 and 2017 and indicates the fair value hierarchy of the valuation inputs utilized to determine such fair value (in thousands): December 31, 2016 Description Balance Sheet Classification Total Level 1 Level 2 Level 3 Assets: Money market funds Cash and cash equivalents $ 766,186 $ 766,186 $ — $ — Total assets $ 766,186 $ 766,186 $ — $ — December 31, 2017 Description Balance Sheet Classification Total Level 1 Level 2 Level 3 Assets: Money market funds Cash and cash equivalents $ 593,955 $ 593,955 $ — $ — Total assets $ 593,955 $ 593,955 $ — $ —
Schedule of estimated useful lives that were used to depreciate the Company's assets:	The following estimated useful lives were used to depreciate the Company’s assets: Estimated Useful Life Furniture and fixtures years Computer equipment and software years Manufacturing equipment years Leasehold improvements Shorter of the useful life or the remaining lease term
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	The following table presents changes in the components of accumulated other comprehensive loss (in thousands): Foreign currency translation adjustments Unrealized loss on pension liability Total Balance at December 31, 2015 $ — $ — $ — Other comprehensive (loss) income (142) (2,782) (2,924) Balance at December 31, 2016 (142) (2,782) (2,924) Other comprehensive (loss) income 401 (3,359) (2,958) Balance at December 31, 2017 $ 259 $ (6,141) $ (5,882)
Schedule of share amount excluded from the calculation of diluted net loss per share due to their anti-dilutive effect	The following table presents amounts that were excluded from the calculation of diluted net loss per share, due to their anti-dilutive effect (in thousands): Years Ended December 31, 2015 2016 2017 Outstanding stock options 5,878 6,979 6,908 Unvested restricted stock units 60 760 1,159 Shares issuable upon conversion of Convertible Notes 492 3,765 2,695 6,430 11,504 10,762
Summary of impact to Company's condensed consolidated Statements of Operations and Comprehensive Loss, Cash Flows, Balance Sheet for early adoption of Accounting Standard Update	Consolidated Statements of Operations and Comprehensive Loss Year Ended December 31, 2015 As revised As originally Effect of change Product revenue, net $ 2,026 $ - $ 2,026 License, collaboration and other revenues 2,012 317 1,695 Cost of sales – product 62 - 62 Loss from operations (232,383) (236,042) 3,659 Net loss (247,749) (251,408) 3,659 Net loss per share applicable to common stockholders - basic and diluted $ (6.29) $ (6.38) $ 0.09 Year Ended December 31, 2016 As revised As originally Effect of change Product revenue, net $ 5,174 $ 6,877 $ (1,703) License, collaboration and other revenues 52,844 37,946 14,898 Cost of sales – product 1,203 1,256 (53) Loss from operations (357,702) (370,950) 13,248 Net loss (374,224) (387,472) 13,248 Net loss per share applicable to common stockholders - basic and diluted $ (7.85) $ (8.13) $ 0.28 Consolidated Balance Sheets December 31, 2016 (in thousands) As revised As originally Effect of change Accounts receivable $ 6,195 $ 5,343 $ 852 Other current assets 10,515 8,919 1,596 Accrued expenses 68,700 68,271 429 Deferred revenue, current 95 288 (193) Deferred revenue, non-current 305 — 305 Customer deposit — 15,000 (15,000) Accumulated deficit $ (973,761) $ (990,668) $ 16,907 Consolidated Statements of Cash Flows Year Ended December 31, 2015 (in thousands) As revised As originally Effect of change Net loss $ (247,749) $ (251,408) $ 3,659 Adjustments to reconcile net loss to net cash used in operating activities: Accounts receivable (2,562) (679) (1,883) Other assets (3,639) (2,128) (1,511) Accrued expenses 20,077 19,646 431 Deferred revenues 92 788 (696) Cash and cash equivalents at beginning of period 256,861 — Cash and cash equivalents at end of period $ $ 230,146 $ — Year Ended December 31, 2016 (in thousands) As revised As originally Effect of change Net loss $ (374,224) $ (387,472) $ 13,248 Adjustments to reconcile net loss to net cash used in operating activities: Accounts receivable (3,634) (4,664) 1,030 Other assets (7,770) (7,685) (85) Accrued expenses 31,896 31,897 (1) Deferred revenues 309 14,501 (14,192) Cash and cash equivalents at beginning of period 230,146 — Cash and cash equivalents at end of period $ $ 785,877 $ —

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2017
Inventories
Schedule of current inventories	December 31, 2016 2017 Raw materials $ 13,263 $ 17,876 Work in process 584 38,629 Finished goods 853 1,434 Total inventories $ 14,700 $ 57,939

Intangible Asset (Tables)

Intangible Asset (Tables)	12 Months Ended
	Dec. 31, 2017
Intangible Assets
Schedule of finite-lived intangible assets	December 31, 2016 2017 Estimated useful life Acquired and in-licensed rights $ 15,000 $ 64,665 8-13 Years Less accumulated amortization (2,123) (8,281) Total intangible assets, net $ 12,877 $ 56,384
Schedule of estimated future amortization expense for finite-lived intangible assets	Total 2018 $ 6,456 2019 6,456 2020 6,460 2021 6,456 2022 6,456 Thereafter 24,100 $ 56,384

Property and Equipment (Tables)

Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property and Equipment
Schedule of property and equipment and related accumulated depreciation	December 31, 2016 2017 Furniture and fixtures $ 2,481 $ 4,212 Computer equipment and software 3,459 4,762 Leasehold improvements 3,190 6,314 Manufacturing equipment 124 350 Total property and equipment, at cost 9,254 15,638 Less accumulated depreciation and amortization (2,614) (5,986) Total property and equipment, net $ 6,640 $ 9,652

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Accrued Expenses
Schedule of accrued expenses	The following table presents the components of accrued expenses (in thousands): December 31, 2016 2017 (as revised) Research and development $ 36,759 $ 55,949 Salaries, bonuses and other compensation 20,654 33,717 Inventory — 16,469 Product revenue allowances 1,407 22,847 Sales and marketing 3,177 6,701 Professional services 2,743 3,944 Royalties 2,059 6,552 Other 1,901 8,629 Total accrued expenses $ 68,700 $ 154,808

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Debt.
Schedule of outstanding debt obligations	Our outstanding debt obligations consisted of the following (in thousands): December 31, 2016 2017 Convertible notes, net $ 131,775 $ 143,446 Term Loan (Tranche A) — 293,659 Total long-term debt $ 131,775 $ 437,105
Schedule of convertible note balances	The Company’s outstanding convertible note balances at December 31, 2017 consisted of the following (in thousands): December 31, 2017 Liability component Principal $ 201,250 Less: debt discount and issuance costs, net (57,804) Net carrying amount $ 143,446 Equity component $ 87,843
Schedule of convertible note interest expense	. The following table sets forth total interest expense recognized related to the Convertible Notes during the years ended December 31, 2016 and 2017 (in thousands): Years Ended December 31, 2016 2017 Contractual interest expense $ 6,037 $ 6,038 Amortization of debt discount 9,851 11,126 Amortization of debt issuance costs 599 545 Total interest expense $ 16,487 $ 17,709
Schedule of future annual principle payments on long-term debt	Future annual principal payments on the Company’s long-term debt as of December 31, 2017 were as follows (in thousands): Total 2018 $ — 2019 9,000 2020 36,000 2021 237,250 2022 36,000 Thereafter 183,000 Total $ 501,250

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Stock-Based Compensation
Schedule of stock-based compensation expense as reflected in the Company's condensed consolidated statements of operations and comprehensive loss	The following table presents stock-based compensation expense as reflected in the Company’s consolidated statements of operations and comprehensive loss (in thousands): Years Ended December 31, 2015 2016 2017 Research and development $ 11,082 $ 19,783 $ 30,810 Selling, general and administrative 14,832 28,672 59,616 Total stock-based compensation expense $ 25,914 $ 48,455 $ 90,426
Summary of the Company's stock option activity and related information	Weighted-average Weighted-average Aggregate exercise price per remaining contractual intrinsic value Shares share term (years) (in thousands) Outstanding at December 31, 2016 6,978,621 $ 40.65 $ 655,099 Granted 693,112 160.53 Exercised (597,209) 43.34 Cancelled (166,211) 59.31 Outstanding at December 31, 2017 6,908,313 $ 52.00 6.8 $ 276,640 Vested at December 31, 2017 4,297,650 $ 33.47 6.0 $ 219,374
Schedule of Black-Scholes assumptions	The fair value of each stock option was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions: Years Ended December 31, 2015 2016 2017 Dividend yield — — — Volatility 63% - 65% 57% - 59% 60% - 64% Risk-free interest rate 1.35% - 1.95% 1.07% - 2.10% 1.79% - 2.30% Expected term (years) 5.50 - 6.08 5.50 - 6.08 5.50 - 6.08
Summary of the Company's restricted stock unit (RSU) activity and related information	Weighted-average grant date fair Shares value per share Unvested restricted stock units at December 31, 2016 760,123 $ 58.55 Granted 656,751 162.79 Vested (199,654) 59.48 Forfeited (58,102) 107.34 Unvested restricted stock units at December 31, 2017 1,159,118 $ 115.01
Schedule of stock-based compensation expense by type of award	The following table presents stock-based compensation expense by type of award (in thousands): Years Ended December 31, 2015 2016 2017 Stock options $ 24,862 $ 40,030 $ 57,500 Restricted stock units (including performance-based RSUs) 742 7,502 31,498 Employee stock purchase plan 310 923 1,428 Total $ 25,914 $ 48,455 $ 90,426

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Taxes
Schedule of components of income before income tax	Years Ended December 31, 2015 2016 2017 (as revised) (as revised) United States $ (210,744) $ (298,969) $ (399,265) Foreign (37,005) (73,780) (95,537) (Loss) income before provision for (benefit from) income taxes $ (247,749) $ (372,749) $ (494,802)
Schedule of components of income tax provision	Years Ended December 31, 2015 2016 2017 Current: Federal $ — $ — $ — State — 3 29 Foreign — 1,597 1,157 — 1,600 1,186 Deferred: Federal — — — State — — — Foreign — (125) 138 — (125) 138 Provision for income taxes $ — $ 1,475 $ 1,324
Schedule of reconciliation of income tax expense (benefit) at the statutory federal income tax rate to the effective income tax rate as reflected in the consolidated financial statements	Years Ended December 31, 2015 2016 2017 (as revised) (as revised) Federal income tax (benefit) expense at statutory rate (34.0) % (35.0) % (35.0) % State income tax (benefit) expense (2.3) (0.4) (1.6) Permanent items 0.2 (0.1) (0.7) Foreign rate differential 5.0 6.0 4.2 Federal research and development credit (1.7) (11.1) (11.8) Tax rate change — — 31.5 Change in valuation allowance 32.8 40.6 12.5 Other 1.2 Effective income tax rate % % %
Schedule of principal components of the Company's deferred tax assets and liabilities	December 31, 2016 2017 Deferred tax assets: (as revised) Federal net operating loss carryforwards $ 231,663 $ 204,495 State net operating loss carryforwards 18,027 26,225 Depreciation and amortization 18,840 16,435 Stock-based compensation 21,393 24,017 Tax credit carryforwards 54,950 107,944 Other 7,374 14,769 Total deferred tax assets 352,247 393,885 Less: valuation allowance (334,468) (384,453) Net deferred tax assets 17,779 9,432 Deferred tax liability: Debt discount on convertible notes (17,654) (9,432) Net deferred taxes $ 125 $ —
Schedule of unrecognized tax benefit roll forward	2016 2017 Balance at January 1 $ — $ 7,744 Increases related to prior year tax positions 4,304 4,010 Increases related to current year tax positions 3,440 9,926 Reductions for tax positions of prior periods — — Decreases related to lapse of applicable statute of limitations — — Decreases related to settlements with tax authorities — — Balance at December 31 $ 7,744 $ 21,680

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies
Schedule of future minimum rental commitments	Operating Leases 2018 $ 9,890 2019 11,616 2020 7,713 2021 3,766 2022 3,566 Thereafter 2,291 Total minimum lease payments $ 38,842

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2017
Revenue Recognition [Abstract]
Summary of activity in each of the product revenue allowance and reserve categories	. The following table summarizes balances and activity in each of the product revenue allowance and reserve categories for the years ended December 31, 2015 (as revised), 2016 (as revised) and 2017 (in thousands): Chargebacks, Government Returns Total Balance at December 31, 2014 $ — $ — $ — $ — Provision related to current period sales 813 422 8 1,243 Adjustment related to prior period sales — — — — Credit or payments made during the period — — — — Balance at December 31, 2015 813 422 8 1,243 Provision related to current period sales 2,231 1,941 10 4,182 Adjustment related to prior period sales — — — — Credit or payments made during the period (2,867) (1,051) — (3,918) Balance at December 31, 2016 177 1,312 18 1,507 Provision related to current period sales 21,732 12,090 16,338 50,160 Adjustment related to prior period sales — 62 — 62 Credit or payments made during the period (19,821) (7,014) (6) (26,841) Balance at December 31, 2017 $ 2,088 $ 6,450 $ 16,350 $ 24,888
Summary of changes in the balances of the contract assets and liabilities	The following table presents changes in the Company’s contract assets and liabilities during the years ended December 31, 2016 (as revised) and 2017 (in thousands): Balance at Additions Deductions Balance at Year ended December 31, 2016 Contract assets $ 1,000 $ — $ — $ 1,000 Contract liabilities: Deferred revenue $ 92 $ 653 $ (345) $ 400 Year ended December 31, 2017 Contract assets $ 1,000 $ — $ — $ 1,000 Contract liabilities: Deferred revenue $ 400 $ — $ (94) $ 306
Schedule of revenue recognized due to changes in contract asset and contract liability balances	During the years ended December 31, 2015, 2016 and 2017, the Company recognized the following revenues as a result of changes in the contract asset and the contract liability balances in the respective periods (in thousands): Years Ended December 31, 2015 2016 2017 Revenue recognized in the period from: (as revised) (as revised) Amounts included in the contract liability at the beginning of the period $ — 93 $ 94 Performance obligations satisfied in previous periods $ — — $ —

Segment Information (Tables)

Segment Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Information
Schedule of revenues by product	Product revenues, net consisted of the following (in thousands): Years Ended December 31, 2015 2016 2017 (as revised) (as revised) ZEJULA $ — $ — $ 108,756 VARUBI/VARUBY 2,026 5,174 11,944 Total product revenues, net $ 2,026 $ 5,174 $ 120,700
Schedule of revenue by geographic area	The following table presents total revenues by geography (in thousands):
Schedule of revenue and accounts receivable of significant customers	Percent of Total Revenues Percent of Accounts Receivable Years Ended December 31, December 31, 2016 2017 2016 2017 (as revised) (as revised) Janssen Biotech, Inc. 63 % * % 26 % * % Zai Lab (Shanghai) Co., Ltd. 27 % * % 11 % * % Takeda Pharmaceutical Co., Ltd. * % 45 % * % * % Jiangsu Hengrui Medicine Co., Ltd. * % * % 10 % * % Distributor "A" * % 32 % 42 % 31 % Distributor "B" * % 11 % * % 49 %
Schedule of property and equipment, net by location	Property and equipment, net by location consisted of the following (in thousands): December 31, 2016 2017 United States $ 6,194 $ 8,583 Switzerland 446 669 Germany — 119 Spain — 281 Total property and equipment, net $ 6,640 $ 9,652

Consolidated Quarterly Financ38

Consolidated Quarterly Financial Data - Unaudited (Tables)	12 Months Ended
	Dec. 31, 2017
Consolidated Quarterly Financial Data - Unaudited
Schedule of unaudited consolidated quarterly financial data	The following table presents unaudited consolidated quarterly financial data for the years ended December 31, 2016 and 2017 (in thousands, except per share data): Three Months Ended March 31, June 30, September 30, December 31, March 31, June 30, September 30, December 31, 2016 2016 2016 2016 2017 2017 2017 2017 (a)(b) (b) (b) (b) Revenues: Product revenue, net $ 276 $ 1,242 $ 1,326 $ 2,330 $ 2,139 $ 28,829 $ 41,755 $ 47,977 License, collaboration and other revenues 24 34,568 (d) 15,661 (e) 2,591 934 635 101,011 (f) 46 Total revenues 300 35,810 16,987 4,921 3,073 29,464 142,766 48,023 Expenses: Cost of sales - product 79 234 378 512 444 3,620 6,216 30,857 (g) Cost of sales - intangible asset amortization 464 463 464 490 2,979 1,254 1,435 Research and development 52,709 50,138 60,783 71,514 66,122 71,400 73,388 97,832 Selling, general and administrative 30,149 36,218 37,685 54,526 69,262 92,979 83,998 90,569 Acquired in-process research and development (c) 4,000 4,000 1,940 9,000 — 7,000 — 3,000 Total expenses 87,401 91,053 101,250 136,016 136,318 177,978 164,856 223,693 Loss from operations (87,101) (55,243) (84,263) (131,095) (133,245) (148,514) (22,090) (175,670) Interest expense (3,981) (4,120) (4,119) (4,267) (4,267) (4,426) (4,424) (6,641) Interest income 102 209 532 597 841 959 1,133 1,214 Other income — — — — — — 243 85 Loss before income taxes (90,980) (59,154) (87,850) (134,765) (136,671) (151,981) (25,138) (181,012) Provision for income taxes — — — 1,475 54 78 139 1,053 Net loss $ (90,980) $ (59,154) $ (87,850) $ (136,240) $ (136,725) $ (152,059) $ (25,277) $ (182,065) Net loss per share - basic and diluted $ (2.22) $ (1.29) $ (1.72) $ (2.59) $ (2.55) $ (2.82) $ (0.47) $ (3.35) Weighted-average shares - basic and diluted 40,966 45,808 51,151 52,589 53,685 53,982 54,241 54,403 (a) Amounts for the quarter ended March 31, 2016 have been retroactively adjusted to reflect an increase in research and development costs and selling, general and administrative costs in the amount of $0.1 million and $0.1 million, respectively, as a result of the adoption of ASU 2016-09. (b) Amounts for each of the quarterly periods for the year ended December 31, 2016 have been revised to reflect the Company’s adoption of ASU No. 2014-09 effective January 1, 2017, with full retrospective application. This ASU amends the guidance for accounting for revenue from contracts with customers. (c) Acquired in-process research and development expenses relate to licensing agreement milestone expenses for the following periods: (i) $4.0 million to AnaptysBio for the quarter ended March 31, 2016; (ii) $4.0 million to AnaptysBio for the quarter ended June 30, 2016; (iii) $1.0 million to AnaptysBio and $0.9 million to Merck for the quarter ended September 30, 2016; (iv) $9.0 million to Merck for the quarter ended December 31, 2016; (v) $7.0 million to AnaptysBio for the quarter ended June 30, 2017; and (vi) $3.0 million to AnaptysBio for the quarter ended December 31, 2017. (d) In the quarter ended June 30, 2016, the Company received $35.0 million and transferred the license and related know-how required under its collaboration agreement with Janssen. $34.6 million of related license revenue was recognized during the quarter. (e) In the quarter ended September 30, 2016, the Company received $15.0 million and transferred the license and related know-how required under its collaboration agreement with Zai Lab. $14.8 million of related license revenue was recognized during the quarter. (f) In the quarter ended September 30, 2017, the Company received $100.0 million and transferred certain patent rights and know-how relating to niraparib to Takeda. The entire amount of related license revenue was recognized during the quarter. (g) Product cost of sales for the quarter ended December 31, 2017 includes a $16.7 million lower of cost or market write-down of VARUBI inventories and a $1.6 million loss on firm purchase commitments.

Description of Business (Detail

Description of Business (Details)	12 Months Ended
	Dec. 31, 2017segment
Description of Business
Number of operating segments	1

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Credit Risk and Revenue (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017USD ($)item	Dec. 31, 2016USD ($)
Concentration Risks, Types, No Concentration Percentage [Abstract]
Number of off-balance sheet financial instruments with credit risk | item	0
Provision for Doubtful Accounts | $	$ 0	$ 0

Summary of Significant Accoun41

Summary of Significant Accounting Policies - Foreign Currency Risk - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Basis of Presentation and Significant Accounting Policies
Foreign Currency Transaction Gain (Loss), before Tax	$ 0.5	$ 0.2

Summary of Significant Accoun42

Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2017
Furniture and Fixtures
Property and Equipment
Estimated Useful Life	5 years
Computer Equipment and Software
Property and Equipment
Estimated Useful Life	3 years
Manufacturing equipment
Property and Equipment
Estimated Useful Life	7 years

Summary of Significant Accoun43

Summary of Significant Accounting Policies - Financial Instruments and Convertible Senior Notes (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Financial Assets and Liabilities Measured At Fair Value
Total assets	$ 593,955	$ 766,186
Fair Value, Inputs, Level 1
Financial Assets and Liabilities Measured At Fair Value
Total assets	593,955	766,186
Money Market Funds
Financial Assets and Liabilities Measured At Fair Value
Cash and cash equivalents	593,955	766,186
Money Market Funds | Fair Value, Inputs, Level 1
Financial Assets and Liabilities Measured At Fair Value
Cash and cash equivalents	$ 593,955	$ 766,186

Summary of Significant Accoun44

Summary of Significant Accounting Policies - Advertising (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Advertising Expenses
Advertising Expense	$ 21.1	$ 9.2	$ 3.6

Summary of Significant Accoun45

Summary of Significant Accounting Policies - Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	$ (2,924)
Other comprehensive income/(loss)	(2,958)	$ (2,924)
Balance at end of period	(5,882)	(2,924)
Foreign currency translation adjustments
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(142)
Other comprehensive income/(loss)	401	(142)
Balance at end of period	259	(142)
Unrealized (loss) on pension liability
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance at beginning of period	(2,782)
Other comprehensive income/(loss)	(3,359)	(2,782)
Balance at end of period	$ (6,141)	$ (2,782)

Summary of Significant Accoun46

Summary of Significant Accounting Policies - Net Loss Per Share (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Loss per Share
Amounts excluded from the calculation of diluted net loss per share due to their anti-dilutive effect	10,762	11,504	6,430
Outstanding stock options
Net Loss per Share
Amounts excluded from the calculation of diluted net loss per share due to their anti-dilutive effect	6,908	6,979	5,878
Unvested restricted stock units
Net Loss per Share
Amounts excluded from the calculation of diluted net loss per share due to their anti-dilutive effect	1,159	760	60
Shares issuable upon conversion of Convertible Notes
Net Loss per Share
Amounts excluded from the calculation of diluted net loss per share due to their anti-dilutive effect	2,695	3,765	492

Summary of Significant Accoun47

Summary of Significant Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revised Statements of Operations and Comprehensive Loss
Revenue	$ 48,023	$ 142,766	$ 29,464	$ 3,073	$ 4,921	$ 16,987	$ 35,810	$ 300	$ 223,326	$ 58,018	$ 4,038
Cost of sales - product	30,857	6,216	3,620	444	512	378	234	79	41,137	1,203	62
Loss from operations	(175,670)	(22,090)	(148,514)	(133,245)	(131,095)	(84,263)	(55,243)	(87,101)	(479,519)	(357,702)	(232,383)
Net loss	$ (182,065)	$ (25,277)	$ (152,059)	$ (136,725)	$ (136,240)	$ (87,850)	$ (59,154)	$ (90,980)	$ (496,126)	$ (374,224)	$ (247,749)
Net loss per share applicable to common stockholders - basic and diluted (in dollars per share)	$ (3.35)	$ (0.47)	$ (2.82)	$ (2.55)	$ (2.59)	$ (1.72)	$ (1.29)	$ (2.22)	$ (9.17)	$ (7.85)	$ (6.29)
Revised Statement of Financial Position
Accounts receivable	$ 53,416				$ 6,195				$ 53,416	$ 6,195
Other current assets	33,511				10,515				33,511	10,515
Accrued expenses	154,808				68,700				154,808	68,700
Deferred revenue, current	324				95				324	95
Deferred revenue, non-current	211				305				211	305
Accumulated deficit	(1,469,887)				(973,761)				(1,469,887)	(973,761)
Revised Statement of Cash Flow
Net loss									(496,126)	(374,224)	$ (247,749)
Adjustments to reconcile net loss to net cash used in operating activities:
Accounts receivable									(47,134)	(3,634)	(2,562)
Other assets									(20,214)	(7,770)	(3,639)
Accrued expenses									80,837	31,896	20,077
Deferred revenues									134	309	92
Cash and cash equivalents at beginning of period				$ 785,877				$ 230,146	785,877	230,146	256,861
Cash and cash equivalents at end of period	643,095				785,877				643,095	785,877	230,146
Zai Lab (Shanghai) Co. Ltd.
Revised Statement of Financial Position
Customer deposit					15,000					15,000
Adjustments to reconcile net loss to net cash used in operating activities:
Customer Advances and Deposits					15,000					15,000
ASU No. 2014-09
Revised Statements of Operations and Comprehensive Loss
Cost of sales - product										1,203	62
Loss from operations										(357,702)	(232,383)
Net loss										$ (374,224)	$ (247,749)
Net loss per share applicable to common stockholders - basic and diluted (in dollars per share)										$ (7.85)	$ (6.29)
Revised Statement of Financial Position
Accounts receivable					6,195					$ 6,195
Other current assets					10,515					10,515
Accrued expenses					68,700					68,700
Deferred revenue, current					95					95
Deferred revenue, non-current					305					305
Accumulated deficit					(973,761)					(973,761)
Revised Statement of Cash Flow
Net loss										(374,224)	$ (247,749)
Adjustments to reconcile net loss to net cash used in operating activities:
Accounts receivable										(3,634)	(2,562)
Other assets										(7,770)	(3,639)
Accrued expenses										31,896	20,077
Deferred revenues										309	92
Cash and cash equivalents at beginning of period				785,877				230,146	785,877	230,146	256,861
Cash and cash equivalents at end of period					785,877					785,877	230,146
Product revenue
Revised Statements of Operations and Comprehensive Loss
Revenue	47,977	$ 41,755	$ 28,829	2,139	2,330	$ 1,326	$ 1,242	276	120,700	5,174	2,026
Product revenue | ASU No. 2014-09
Revised Statements of Operations and Comprehensive Loss
Revenue										5,174	2,026
Licenses, collaboration and other revenues
Revised Statements of Operations and Comprehensive Loss
Revenue	$ 46	$ 101,011	$ 635	934	2,591	15,661	$ 34,568	24	102,626	52,844	2,012
Licenses, collaboration and other revenues | Zai Lab (Shanghai) Co. Ltd.
Revised Statements of Operations and Comprehensive Loss
Revenue						$ 14,800
Licenses, collaboration and other revenues | ASU No. 2014-09
Revised Statements of Operations and Comprehensive Loss
Revenue										52,844	2,012
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | ASU No. 2014-09
Revised Statements of Operations and Comprehensive Loss
Cost of sales - product										(53)	62
Loss from operations										13,248	3,659
Net loss										$ 13,248	$ 3,659
Net loss per share applicable to common stockholders - basic and diluted (in dollars per share)										$ 0.28	$ 0.09
Revised Statement of Financial Position
Accounts receivable					852					$ 852
Other current assets					1,596					1,596
Accrued expenses					429					429
Deferred revenue, current					(193)					(193)
Deferred revenue, non-current					305					305
Customer deposit					(15,000)					(15,000)
Accumulated deficit					16,907					16,907
Revised Statement of Cash Flow
Net loss										13,248	$ 3,659
Adjustments to reconcile net loss to net cash used in operating activities:
Accounts receivable										1,030	(1,883)
Other assets										(85)	(1,511)
Accrued expenses										(1)	431
Deferred revenues										(14,192)	(696)
Customer Advances and Deposits					(15,000)					(15,000)
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Product revenue | ASU No. 2014-09
Revised Statements of Operations and Comprehensive Loss
Revenue										(1,703)	2,026
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Licenses, collaboration and other revenues | ASU No. 2014-09
Revised Statements of Operations and Comprehensive Loss
Revenue										14,898	1,695
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | ASU No. 2014-09
Revised Statements of Operations and Comprehensive Loss
Cost of sales - product										1,256
Loss from operations										(370,950)	(236,042)
Net loss										$ (387,472)	$ (251,408)
Net loss per share applicable to common stockholders - basic and diluted (in dollars per share)										$ (8.13)	$ (6.38)
Revised Statement of Financial Position
Accounts receivable					5,343					$ 5,343
Other current assets					8,919					8,919
Accrued expenses					68,271					68,271
Deferred revenue, current					288					288
Customer deposit					15,000					15,000
Accumulated deficit					(990,668)					(990,668)
Revised Statement of Cash Flow
Net loss										(387,472)	$ (251,408)
Adjustments to reconcile net loss to net cash used in operating activities:
Accounts receivable										(4,664)	(679)
Other assets										(7,685)	(2,128)
Accrued expenses										31,897	19,646
Deferred revenues										14,501	788
Cash and cash equivalents at beginning of period				$ 785,877				$ 230,146	$ 785,877	230,146	256,861
Cash and cash equivalents at end of period					785,877					785,877	230,146
Customer Advances and Deposits					$ 15,000					15,000
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Product revenue | ASU No. 2014-09
Revised Statements of Operations and Comprehensive Loss
Revenue										6,877
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Licenses, collaboration and other revenues | ASU No. 2014-09
Revised Statements of Operations and Comprehensive Loss
Revenue										$ 37,946	$ 317

Inventories (Details)

Inventories (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Inventories
Raw materials	$ 17,876	$ 17,876	$ 13,263
Work in process	38,629	38,629	584
Finished goods	1,434	1,434	853
Total inventories	57,939	57,939	$ 14,700
Write-Down of inventory to net realizable value		$ 16,730
Write Down to Lower Of Cost Or Market And Losses On Firm Purchase Commitments [Member]
Inventories
Impairment Effect on Earnings Per Share, after Tax		$ (0.34)
Write Down to Lower Of Cost Or Market And Losses On Firm Purchase Commitments [Member] | VARUBI/VARUBY
Inventories
Write-Down of inventory to net realizable value		$ 18,300
Write Down To Lower Of Cost Or Market | VARUBI/VARUBY
Inventories
Write-Down of inventory to net realizable value	16,700	16,700
Write Down Due To Loss On Firm Purchase Commitments
Inventories
Write-Down of inventory to net realizable value	$ 1,600	$ 1,600

Intangible Assets (Details)

Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Intangible Assets
Acquired and in-licensed rights	$ 64,665	$ 15,000
Less: accumulated amortization	(8,281)	(2,123)
Total intangible asset, net	56,384	12,877
Amortization expense	6,200	$ 1,900	$ 300
Estimated future amortization expense
2,018	6,456
2,019	6,456
2,020	6,460
2,021	6,456
2,022	6,456
Thereafter	$ 24,100
Use Rights [Member] | Minimum
Intangible Assets
Estimated useful life	8 years
Use Rights [Member] | Maximum
Intangible Assets
Estimated useful life	13 years
OPKO Health Inc | Achievement Of First Commercial Sale Of VARUBY In Europe
Intangible Assets
Milestone payment paid	$ 10,000
Merck Sharp & Dohme B.V. | Achievement Of FDA Approval Of ZEJULA
Intangible Assets
Milestone payment paid	25,000
Merck Sharp & Dohme B.V. | Achievement Of EMA Approval Of ZEJULA
Intangible Assets
Milestone payment paid	$ 14,700

Property and Equipment (Details

Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property and Equipment
Gross	$ 15,638	$ 9,254
Less accumulated depreciation and amortization	(5,986)	(2,614)
Property, Plant and Equipment, Net, Total	9,652	6,640
Depreciation expense	3,400	1,300	$ 800
Furniture and Fixtures
Property and Equipment
Gross	4,212	2,481
Computer Equipment and Software
Property and Equipment
Gross	4,762	3,459
Leasehold Improvements
Property and Equipment
Gross	6,314	3,190
Manufacturing equipment
Property and Equipment
Gross	$ 350	$ 124

Accrued Expenses (Details)

Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accrued Expenses
Research and development	$ 55,949	$ 36,759
Salaries, bonuses and other compensation	33,717	20,654
Inventory	16,469
Product revenue allowances	22,847	1,407
Sales and marketing	6,701	3,177
Professional services	3,944	2,743
Royalties	6,552	2,059
Other	8,629	1,901
Total accrued expenses	$ 154,808	$ 68,700

Debt - Obligations (Details)

Debt - Obligations (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Debt.
Convertible notes, net	$ 143,446	$ 131,775
Term Loan (Tranche A)	293,659
Total long-term debt	$ 437,105	$ 131,775

Debt - Convertible Notes (Detai

Debt - Convertible Notes (Details)	Sep. 29, 2014USD ($)$ / shares	Dec. 31, 2017USD ($)item	Sep. 24, 2014USD ($)
Debt
Proceeds from issuance of convertible notes, net of issuance costs		$ 293,596,000
Convertible senior notes due October 2021
Debt
Principal	$ 201,300,000	201,250,000	$ 201,300,000
Proceeds from issuance of convertible notes, net of issuance costs	194,700,000
Debt issuance costs paid	6,600,000
Capped call transactions payments	$ 20,800,000
Interest rate (as a percent)	3.00%
Conversion price per share of convertible notes into common stock | $ / shares	$ 35.13
Convertible notes conversion ratio per 1,000 principal	28.4627
Current share price premium over convertible note conversion share price ( as a percent )	35.00%
Denominator Of Principal Amount Denomination For Conversion Into Common Stock	$ 1,000
Sinking fund provided		$ 0
Repurchase price as a percent of principal amount of convertible notes	100.00%
Fair value of the liability component of convertible debt	$ 113,400,000
Convertible senior notes due October 2021 | Conversion of convertible notes into common stock after December 31,2014
Debt
Convertible threshold trading days | item		20
Convertible threshold consecutive trading days | item		30
Minimum threshold percentage of stock price trigger		130.00%
Convertible senior notes due October 2021 | Conversion of convertible notes when common share trading price is less than 98% of target ratio
Debt
Convertible threshold trading days | item		5
Convertible threshold consecutive trading days | item		10
Denominator Of Principal Amount Denomination For Conversion Into Common Stock		$ 1,000
Threshold percentage forcing conversion when less than share price times conversion ratio		98.00%
Convertible senior notes due October 2021 | Conversion of convertible notes on or after April 1 , 2021
Debt
Days before maturity when notes holder can convert the notes		2 days
Minimum principal that holders may convert at or immediately before maturity		$ 1,000

Debt - Convertible balances and

Debt - Convertible balances and terms (Details) - USD ($) $ in Thousands	Sep. 29, 2014	Dec. 31, 2017	Dec. 31, 2016	Sep. 24, 2014
Liability component
Net carrying amount		$ 143,446	$ 131,775
Convertible senior notes due October 2021
Liability component
Principal	$ 201,300	201,250		$ 201,300
Less: debt discount and issuance costs, net		(57,804)
Net carrying amount		143,446
Equity component		87,843
Convertible Note Issuance Terms Abstract
Debt issuance costs paid	$ 6,600
Equity component of debt issuance costs		2,900
Debt component of issuance costs recorded as an asset		$ 3,700
Expected term for fair value		7 years
Convertible Debt, Fair Value Disclosures		$ 499,100
Debt effective interest rate ( as a percent )		12.90%

Debt - Interest expense (Detail

Debt - Interest expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest expense
Total interest expense	$ 6,641	$ 4,424	$ 4,426	$ 4,267	$ 4,267	$ 4,119	$ 4,120	$ 3,981	$ 19,758	$ 16,487	$ 15,414
Convertible senior notes due October 2021
Interest expense
Contractual interest expense									6,038	6,037
Amortization of debt discount									11,126	9,851
Amortization of debt issuance costs									545	599
Total interest expense									$ 17,709	$ 16,487

Debt - Derivatives (Details)

Debt - Derivatives (Details) - Convertible senior notes due October 2021 - Capped call option	Sep. 29, 2014USD ($)$ / shares
Capped call option transactions
Strike price ( in dollars per share ) | $ / shares	$ 35.13
Cap price ( in dollars per share )	$ 45.54
Capped calls cost charged to stockholders' equity	$ 20,800,000

Debt - 2017 Term Loan Agreement

Debt - 2017 Term Loan Agreement $ in Millions	1 Months Ended
	Dec. 31, 2017	Nov. 30, 2017USD ($)tranche
Minimum
Term loan agreement
Debt Instrument, Interest Rate, Stated Percentage		1.00%
LIBOR | Maximum
Term loan agreement
Debt Instrument, Basis Spread on Variable Rate	1.50%
2017 Term Loan Facility
Term loan agreement
Number of tranches | tranche		2
2017 Term Loan Facility | Maximum
Term loan agreement
Aggregate principal amount		$ 500
2017 Term Loan Facility | Wholly owned domestic subsidiaries
Term loan agreement
Percent of equity interests in subsidiaries securing the term loan agreement		100.00%
2017 Term Loan Facility | Directly owned foreign subsidiaries
Term loan agreement
Percent of equity interests in subsidiaries securing the term loan agreement		65.00%
2017 Term Loan Facility | Tranche A
Term loan agreement
Aggregate principal amount		$ 300
Up-front fee		2.00%
2017 Term Loan Facility | Tranche A | LIBOR
Term loan agreement
Debt Instrument, Description of Variable Rate Basis		London Interbank Offered Rate, or LIBOR
Debt Instrument, Basis Spread on Variable Rate		8.00%
2017 Term Loan Facility | Tranche B
Term loan agreement
Up-front fee		2.00%
2017 Term Loan Facility | Tranche B | Minimum
Term loan agreement
Aggregate principal amount		$ 50
2017 Term Loan Facility | Tranche B | Maximum
Term loan agreement
Aggregate principal amount		$ 200
2017 Term Loan Facility | Tranche B | LIBOR
Term loan agreement
Debt Instrument, Basis Spread on Variable Rate		7.50%
2017 Term Loan Facility | Tranche B | From June 30 2018 To December 20 2018
Term loan agreement
Period of notice to draw on loan under second tranche	90 days

Debt - Term loan payments (Deta

Debt - Term loan payments (Details) - 2017 Term Loan Facility	1 Months Ended
	Nov. 30, 2017
Term loan payments
Frequency of periodic payments	quarterly
Tranche A
Term loan payments
Periodic principle payments as a percent of total principle	3.00%
Date of first required periodic principle payment	Dec. 31, 2019
Prepayment Prior To 24th Anniversary Of Closing Date [Member]
Term loan payments
Prepayment premium percentage	3.00%
Prepayment Prior To 36th Anniversary Of Closing Date [Member]
Term loan payments
Prepayment premium percentage	2.00%
Prepayment Prior To 48th Anniversary Of Closing Date [Member]
Term loan payments
Prepayment premium percentage	1.00%

Debt - Term loan discount and c

Debt - Term loan discount and costs (Details) - USD ($) $ in Thousands

1 Months Ended

3 Months Ended

12 Months Ended

Nov. 30, 2017

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2016

Sep. 30, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Interest expense

Interest Expense

$ 6,641

$ 4,424

$ 4,426

$ 4,267

$ 4,267

$ 4,119

$ 4,120

$ 3,981

$ 19,758

$ 16,487

$ 15,414

2017 Term Loan Facility | Minimum

Debt

Amount of uninsured final judgment causing event of default

$ 10,000

2017 Term Loan Facility | Tranche A

Debt Instrument, Unamortized Discount [Abstract]

Debt discount

6,000

6,000

Debt Issuance Costs, Net [Abstract]

Deferred financing costs

$ 400

400

Interest expense

Additional interest expense related to accretion of debt discount and amortization of deferred financing costs

$ 100

Effective annual interest rate

10.00%

Interest Expense

$ 2,000

Debt - Maturities (Details)

Debt - Maturities (Details) $ in Thousands	Dec. 31, 2017USD ($)
Future annual principal payments
2,018
2,019	9,000
2,020	36,000
2,021	237,250
2,022	36,000
Thereafter	183,000
Total	$ 501,250

Stockholders' Equity (Details)

Stockholders' Equity (Details) $ / shares in Units, $ in Thousands	1 Months Ended					12 Months Ended
	Nov. 30, 2016USD ($)$ / sharesshares	Jul. 31, 2016USD ($)$ / shares	Apr. 30, 2016USD ($)$ / sharesshares	Mar. 31, 2016USD ($)$ / sharesshares	Mar. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2017USD ($)item$ / sharesshares	Dec. 31, 2016USD ($)$ / sharesshares	Dec. 31, 2015USD ($)
Convertible Preferred Stock and Stockholders' Equity
Preferred Stock, Shares Authorized						10,000,000	10,000,000
Common Stock, Shares Authorized						100,000,000	100,000,000
Preferred Stock, Par or Stated Value Per Share | $ / shares						$ 0.0001	$ 0.0001
Common Stock, Par or Stated Value Per Share | $ / shares						$ 0.0001	$ 0.0001
Preferred Stock, Shares Issued						0	0
Preferred Stock, Shares Outstanding						0	0
Common Stock, Shares, Issued						54,464,039	53,621,679
Common Stock, Shares, Outstanding						54,464,039	53,621,679
Shares Issued, Price Per Share | $ / shares	$ 135	$ 81	$ 44.24	$ 35.19
Gross proceeds from the sale of common stock in an underwritten public offering | $	$ 236,300	$ 433,100		$ 155,000
Net proceeds from issuance of common stock | $	$ 224,200	$ 408,900	$ 50,000			$ (8)	$ 838,099	$ 179,753
Common Stock
Convertible Preferred Stock and Stockholders' Equity
Stock Issued During Period, Shares, New Issues	1,750,000		1,130,198	4,404,658	3,755,000	5,347,500
Shares Issued, Price Per Share | $ / shares					$ 51
Gross proceeds from the sale of common stock in an underwritten public offering | $					$ 191,500
Net proceeds from issuance of common stock | $					$ 179,800
Number of votes per share | item						1

Stock-Based Compensation - Stoc

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-based compensation expense
Total stock-based compensation expense	$ 90,426	$ 48,455	$ 25,914
Research and development
Stock-based compensation expense
Total stock-based compensation expense	30,810	19,783	11,082
Selling, general and administrative
Stock-based compensation expense
Total stock-based compensation expense	$ 59,616	$ 28,672	$ 14,832

Stock-Based Compensation - St63

Stock-Based Compensation - Stock Compensation Plans (Details) - USD ($) $ in Thousands	Apr. 27, 2012	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2018	Jan. 01, 2017	May 14, 2015	Jan. 01, 2012
Stock-Based Compensation
Vesting percentage		25.00%
Number of shares authorized for grant under the plan								1,981,130
Number of shares available for future grants that were added to the total number of shares reserved for issuance	6,857
Annual increase in common stock available for grant as a percentage of common stock outstanding		4.00%
Maximum Number of shares granted to non-employee director per year		50,000
Restricted Common Stock
Allocated Share-based Compensation Expense		$ 90,426	$ 48,455	$ 25,914
Outstanding stock options
Stock-Based Compensation
Vesting period		4 years
Exercisable period from date of grant		10 years
Number of shares available for future grants that were added to the total number of shares reserved for issuance					2,178,561	2,144,867
Restricted Common Stock
Allocated Share-based Compensation Expense		$ 57,500	$ 40,030	$ 24,862
Weighted average period over which unrecognized compensation costs are expected to be recognized		2 years 1 month 6 days
Outstanding stock options | Vesting One Year from Awards Vesting Start Date
Stock-Based Compensation
Vesting percentage		25.00%
Vesting period		1 year
Outstanding stock options | Vesting over Subsequent 36 Months
Stock-Based Compensation
Vesting percentage		75.00%
Vesting period		36 months
Omnibus Incentive Plan 2012
Stock-Based Compensation
Number of shares authorized for grant under the plan	1,428,571
Number of additional shares authorized under the plan	6,857
Omnibus Incentive Plan 2012 | Outstanding stock options
Stock-Based Compensation
Number of shares remaining available for grant		1,810,240
Director Incentive Plan 2015 | Outstanding stock options
Stock-Based Compensation
Number of shares authorized for grant under the plan							500,000
Number of shares remaining available for grant		198,433

Stock-Based Compensation - St64

Stock-Based Compensation - Stock Options (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Weighted-average remaining contractual term (in years)
Outstanding				6 years 9 months 18 days	7 years 7 months 6 days
Vested at the end of the period				6 years
Aggregate intrinsic value
Outstanding at the beginning of the period				$ 655,099
Outstanding at the end of the period				276,640	$ 655,099
Vested at the end of the period				219,374
Assumptions used to calculate fair value of employee stock option at the date of grant
Allocated Share-based Compensation Expense				90,426	48,455	$ 25,914
Total unrecognized compensation cost related to unvested stock options (in dollars)				110,300
Aggregate value of shares issued to certain non-employee board members in lieu of fees				$ 464	$ 345	$ 266
Outstanding stock options
Shares
Outstanding at the beginning of the period (in shares)				6,978,621
Granted (in shares)				693,112
Exercised (in shares)				(597,209)
Cancelled (in shares)				(166,211)
Outstanding at the end of the period (in shares)				6,908,313	6,978,621
Vested at the end of the period (in shares)				4,297,650
Weighted-average price per share
Outstanding at the beginning of the period (in dollars per share)				$ 40.65
Granted (in dollars per share)				160.53
Exercised (in dollars per share)				43.34
Cancelled (in dollars per share)				59.31
Outstanding at the end of the period (in dollars per share)				52	$ 40.65
Vested at the end of the period (in dollars per share)				33.47
Assumptions used to calculate fair value of employee stock option at the date of grant
Weighted-average grant date fair value of options granted (in dollars per share)				$ 94.50	$ 32.13	$ 32.05
Aggregate intrinsic value of options exercised				$ 57,100	$ 37,400	$ 11,800
Allocated Share-based Compensation Expense				$ 57,500	$ 40,030	$ 24,862
Weighted average period over which unrecognized compensation costs are expected to be recognized				2 years 1 month 6 days
Shares issued during the period	3,111	6,027	3,429
Outstanding stock options | Minimum
Assumptions used to calculate fair value of employee stock option at the date of grant
Volatility (as a percent)				60.00%	57.00%	63.00%
Risk-free interest rate (as a percent)				1.79%	1.07%	1.35%
Expected term				5 years 6 months	5 years 6 months	5 years 6 months
Outstanding stock options | Maximum
Assumptions used to calculate fair value of employee stock option at the date of grant
Volatility (as a percent)				64.00%	59.00%	65.00%
Risk-free interest rate (as a percent)				2.30%	2.10%	1.95%
Expected term				6 years 29 days	6 years 29 days	6 years 29 days

Stock-Based Compensation - Rest

Stock-Based Compensation - Restricted Stock Units (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Stock Units
Stock-based compensation expense	$ 90,426	$ 48,455	$ 25,914
Weighted-average grant date fair value per share
Total grant date fair value of vested restricted stock	$ 11,900	$ 1,100	$ 500
Restricted Stock Units
Restricted Stock Units
Unvested RSUs at the beginning of the period (in shares)		760,123
Granted (in shares)	656,751
Vested (in shares)	(199,654)
Forfeited (in shares)	(58,102)
Unvested RSUs at the end of the period (in shares)	1,159,118		760,123
Stock-based compensation expense	$ 31,498	$ 7,502	$ 742
Weighted-average grant date fair value per share
Unvested RSUs at the beginning of the period (in dollars per share)		$ 58.55
Granted (in dollars per share)	$ 162.79	58.47	$ 56
Vested (in dollars per share)	59.48
Forfeited (in dollars per share)	107.34
Unvested RSUs at the end of the period (in dollars per share)	$ 115.01		58.55
Unrecognized compensation costs	$ 107,300
Weighted average period over which unrecognized compensation costs are expected to be recognized	2 years 9 months 18 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 162.79	$ 58.47	$ 56
Service and performance conditions | Restricted Stock Units
Restricted Stock Units
Granted (in shares)	15,000
Vested (in shares)	(11,512)
Stock-based compensation expense	$ 900	$ 400

Stock-Based Compensation - Empl

Stock-Based Compensation - Employee Stock Purchase Plan (Details) - Employee stock purchase plan - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jun. 18, 2012
Employee Stock Purchase Plan
Shares reserved for issuance under ESPP				275,000
Number of shares remaining available for grant	151,859
Offering period	6 months
Purchase price of the common stock as a percentage of the lower of the fair market value of a share of common stock on the first trading date of each offering period or on the last trading day of the offering period	85.00%
Maximum fair market value of common stock that may be purchased by each participant per year	$ 25,000
Shares issued under ESPP	42,386	42,478	20,601

Stock-Based Compensation - Comp

Stock-Based Compensation - Compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock-based compensation expense
Stock-based compensation expense	$ 90,426	$ 48,455	$ 25,914
Employee stock purchase plan
Stock-based compensation expense
Stock-based compensation expense	1,428	923	310
Outstanding stock options
Stock-based compensation expense
Stock-based compensation expense	57,500	40,030	24,862
Restricted Stock Units
Stock-based compensation expense
Stock-based compensation expense	$ 31,498	$ 7,502	$ 742

Income Taxes - Income_Loss Befo

Income Taxes - Income/Loss Before Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of income before taxes
United States									$ (399,265)	$ (298,969)	$ (210,744)
Foreign.									(95,537)	(73,780)	(37,005)
Loss before income taxes	$ (181,012)	$ (25,138)	$ (151,981)	$ (136,671)	$ (134,765)	$ (87,850)	$ (59,154)	$ (90,980)	$ (494,802)	$ (372,749)	$ (247,749)

Income Taxes - Provision for In

Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended					12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Current:
State						$ 29	$ 3
Foreign						1,157	1,597
Current Income Tax Expense (Benefit), Total						1,186	1,600
Deferred:
State						138	(125)
Deferred Income Tax Expense (Benefit), Total						138	(125)
Income Tax Expense (Benefit), Total	$ 1,053	$ 139	$ 78	$ 54	$ 1,475	$ 1,324	$ 1,475

Income Taxes - Statutory Federa

Income Taxes - Statutory Federal rate reconciliation (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of income tax expense (benefit) at the statutory federal income tax rate to the effective income tax rate as reflected in the consolidated financial statements
Federal income tax (benefit)/ expense at statutory rate (as a percent)	(35.00%)	(35.00%)	(34.00%)
State income tax benefit (as a percent)	(1.60%)	(0.40%)	(2.30%)
Permanent items (as a percent)	(0.70%)	(0.10%)	0.20%
Foreign rate differential	4.20%	6.00%	5.00%
Federal research and development credit (as a percent)	(11.80%)	(11.10%)	(1.70%)
Tax rate change	31.50%
Change in valuation allowance (as a percent)	12.50%	40.60%	32.80%
Other	1.20%	0.40%	(0.00%)
Effective income tax rate (as a percent)	0.30%	0.40%	(0.00%)

Income Taxes - Deferred tax ass

Income Taxes - Deferred tax assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets :
Federal net operating loss carryforwards	$ 204,495	$ 231,663
State net operating loss carryforwards	26,225	18,027
Depreciation and amortization	16,435	18,840
Stock-based compensation	24,017	21,393
Tax credit carryforwards	107,944	54,950
Other	14,769	7,374
Total deferred tax assets	393,885	352,247
Less valuation allowance	(384,453)	(334,468)
Net deferred tax assets	9,432	17,779
Deferred tax liability:
Debt discount on convertible notes	(9,432)	(17,654)
Deferred Tax Assets, Net		$ 125
Increase in valuation allowance, deferred tax asset	$ (50,000)

Income Taxes - Tax Cuts and Job

Income Taxes - Tax Cuts and Jobs Act (Details)	Jan. 01, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Effect of Tax Cuts and Jobs Act 2017
Federal statutory rate		35.00%	35.00%	34.00%
Forecast
Effect of Tax Cuts and Jobs Act 2017
Federal statutory rate	21.00%

Income Taxes - NOL and tax cred

Income Taxes - NOL and tax credit carryforwards (Details) $ in Millions	Dec. 31, 2017USD ($)
Federal.
Income Taxes
Net operating loss carryforwards	$ 963.9
Federal. | General business tax credit
Income Taxes
Tax credit carryforwards	102.1
State
Income Taxes
Net operating loss carryforwards	449.5
State | Research and Development tax credits
Income Taxes
Tax credit carryforwards	7.4
Foreign.
Income Taxes
Net operating loss carryforwards	$ 14.2

Income Taxes - Unrecognized tax

Income Taxes - Unrecognized tax benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of unrecognized tax benefit
Balance at beginning of period	$ 7,744
Increases related to prior year tax positions	4,010	$ 4,304
Increases related to current year tax positions	9,926	3,440
Balance at end of period	21,680	7,744
Gross unrecognized tax benefits	7,744	7,744	$ 21,680	$ 7,744
Accrued interest or penalties related to uncertain tax positions			0	$ 0
Interest or penalty expense recognized related to uncertain tax positions	0	$ 0
Research and Development tax credits
Reconciliation of unrecognized tax benefit
Balance at end of period	4,000
Gross unrecognized tax benefits	4,000		4,000
Allocation Of Taxable Income
Reconciliation of unrecognized tax benefit
Balance at end of period	9,900
Gross unrecognized tax benefits	$ 9,900		$ 9,900

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Millions	Jan. 01, 2012	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Percentage of eligible compensation, matched 100% by employer		100.00%
Employer match of employee deferral contributions of first 3% of compensation (as a percent)	3.00%
Percentage of eligible compensation, matched 50% by employer		50.00%
Employer match of employee deferral contributions of next 2% of compensation (as a percent)		2.00%
Aggregate matching contribution to the 401(k) plan		$ 4.2	$ 2.2	$ 1
Defined benefit plan | Foreign Plan
Defined Benefit Plan, Fair Value of Plan Assets		9.9
Pension Cost (Reversal of Cost)		1.3
Defined benefit plan | Foreign Plan | Unfunded Plan
Liability, Defined Benefit Pension Plan		$ 6.5

Commitments and Contingencies76

Commitments and Contingencies (Details) $ in Thousands	Dec. 18, 2017USD ($)ft²	Dec. 31, 2017USD ($)ft²	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2017USD ($)ft²item
Commitments and Contingencies
Number of lease amendments increasing office space | item					7
Tenant improvement allowances	$ 2,900	$ 3,000
Future minimum rental commitments
Operating Lease Due - Current		9,890			$ 9,890
2,018		11,616			11,616
2,019		7,713			7,713
2,020		3,766			3,766
2,021		3,566			3,566
2,022		2,291			2,291
Total minimum lease payments		38,842			$ 38,842
Operating Leases, Rent Expense, Net		$ 5,400	$ 3,400	$ 2,100
Amendment of Operating Lease
Commitments and Contingencies
Leased office space (in square feet) | ft²		180,000			180,000
Waltham, Massachusetts
Commitments and Contingencies
Square footage added to existing leased office space | ft²	83,000

Revenue Recognition - Product r

Revenue Recognition - Product revenue allowance and reserve categories (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Activity in each of the product revenue allowance and reserve categories
Balance at the beginning	$ 1,507	$ 1,243
Provision related to current period sales	50,160	4,182	$ 1,243
Adjustment related to prior period sales	62
Credit or payments made during the period	(26,841)	(3,918)
Balance at the end	24,888	1,507	1,243
Chargebacks, discounts and fees
Activity in each of the product revenue allowance and reserve categories
Balance at the beginning	177	813
Provision related to current period sales	21,732	2,231	813
Credit or payments made during the period	(19,821)	(2,867)
Balance at the end	2,088	177	813
Government and other rebates
Activity in each of the product revenue allowance and reserve categories
Balance at the beginning	1,312	422
Provision related to current period sales	12,090	1,941	422
Adjustment related to prior period sales	62
Credit or payments made during the period	(7,014)	(1,051)
Balance at the end	6,450	1,312	422
Returns
Activity in each of the product revenue allowance and reserve categories
Balance at the beginning	18	8
Provision related to current period sales	16,338	10	8
Credit or payments made during the period	(6)
Balance at the end	$ 16,350	$ 18	$ 8

Revenue Recognition - contract

Revenue Recognition - contract assets and liabilities (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Contract assets.
Contract assets	$ 1,000	$ 1,000	$ 1,000
Contract liabilities:
Deferred Revenue, Beginning Balance		400	92
Additions			653
Deductions		(94)	(345)
Deferred Revenue, Ending Balance	$ 92	$ 306	$ 400

Revenue Recognition - performan

Revenue Recognition - performance of obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Revenue Recognition [Abstract]
Amounts included in the contract liability in the beginning of the period	$ 94	$ 93

License and Collaboration Agree

License and Collaboration Agreements - Rolapitant in-license (Details) - USD ($) $ in Thousands

1 Months Ended

3 Months Ended

12 Months Ended

85 Months Ended

Dec. 31, 2010

Dec. 31, 2017

Sep. 30, 2017

Jun. 30, 2017

Mar. 31, 2017

Dec. 31, 2016

Sep. 30, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Dec. 31, 2017

License Agreements

Fair value of shares issued

$ 93

$ 691

Cost of sales - product

$ 30,857

$ 6,216

$ 3,620

$ 444

$ 512

$ 378

$ 234

$ 79

$ 41,137

$ 1,203

$ 62

Milestone payments capitalized as intangible assets

25,000

VARUBI/VARUBY

License Agreements

Cost of sales - product

$ 2,000

License Agreement | OPKO Health Inc

License Agreements

Up-front fees paid

$ 6,000

Fair value of shares issued

600

Period within which any shortfall payment is due prior to calendar year end

45 days

Acquired in-process research and development

$ 6,600

License Agreement | VARUBI/VARUBY | OPKO Health Inc

License Agreements

Minimum annual royalty per agreement

$ 2,500

Period that minimum annual royalty payments are required per agreement

5 years

Royalties incurred on VARUBI sales

$ 700

License Agreement | Achievement Of Specific Regulatory Milestones in the U.S. and Europe | OPKO Health Inc

License Agreements

Payments for milestones achieved

$ 30,000

License Agreement | Achievement of sales milestones | OPKO Health Inc | Maximum

License Agreements

Potential milestone payments to be paid

85,000

License Agreement | Other Assets | OPKO Health Inc

License Agreements

Additional royalty obligation accrued

$ 1,800

License and Collaboration Agr81

License and Collaboration Agreements - Niraparib In-License (Details) - USD ($) $ in Thousands

1 Months Ended

3 Months Ended

12 Months Ended

68 Months Ended

Jun. 30, 2012

May 31, 2012

Dec. 31, 2017

Jun. 30, 2017

Dec. 31, 2016

Sep. 30, 2016

Jun. 30, 2016

Mar. 31, 2016

Dec. 31, 2017

Dec. 31, 2016

Dec. 31, 2015

Dec. 31, 2017

License Agreements

Acquired in-process research and development expense

$ 3,000

$ 7,000

$ 9,000

$ 1,940

$ 4,000

$ 4,000

$ 10,000

$ 18,940

$ 2,000

Merck Sharp & Dohme B.V.

License Agreements

Payments for milestones achieved

$ 52,200

License Agreement | Merck Sharp & Dohme B.V.

License Agreements

Up-front fees paid

$ 7,000

Acquired in-process research and development expense

$ 7,000

Payments for milestones achieved

39,500

License Agreement | Maximum | Achievement of development and regulatory milestones for first indication | Merck Sharp & Dohme B.V.

License Agreements

Potential milestone payments to be paid

$ 57,000

License Agreement | Maximum | Achievement of development and regulatory milestones for successive indications [Member] | Merck Sharp & Dohme B.V.

License Agreements

Potential milestone payments to be paid

$ 29,500

License Agreement | Maximum | Achievement of sales milestones | Merck Sharp & Dohme B.V.

License Agreements

Potential milestone payments to be paid

$ 87,500

License Agreement | Intangible Assets | Merck Sharp & Dohme B.V.

License Agreements

Payments for milestones achieved

$ 40,000

License and Collaboration Agr82

License and Collaboration Agreements - Immuno-Oncology Platform License (Details) $ in Thousands	1 Months Ended	3 Months Ended								12 Months Ended				46 Months Ended
	Mar. 31, 2014USD ($)item	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Sep. 30, 2016USD ($)	Jun. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Dec. 31, 2017USD ($)item	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2017USD ($)
License Agreements
Number of assets acquired with future alternative use | item	0
Acquired in-process research and development expense		$ 3,000		$ 7,000		$ 9,000	$ 1,940	$ 4,000	$ 4,000	$ 10,000	$ 18,940	$ 2,000
Research and development expense		$ 97,832	$ 73,388	$ 71,400	$ 66,122	$ 71,514	$ 60,783	$ 50,138	$ 52,709	$ 308,742	235,144	$ 155,390
Collaboration and Exclusive License Agreement
License Agreements
Prior written notice to terminate programs	90 days
Collaboration and Exclusive License Agreement | Anaptys Bio Inc
License Agreements
Number of development programs | item										4
Up-front fees paid													$ 19,000
Payments for milestones achieved										$ 10,000				$ 21,000
Acquired in-process research and development expense										19,000
Up-front payments ascribed to future services receivable										0
Research and development expense										$ 0	$ 3,300
Collaboration and Exclusive License Agreement | Maximum | Achievement of research and development milestones | Anaptys Bio Inc
License Agreements
Potential milestone payments to be paid	$ 18,000
Collaboration and Exclusive License Agreement | Maximum | Achievement of certain U.S. and non-U.S. regulatory submissions and approvals milestones | Anaptys Bio Inc
License Agreements
Potential milestone payments to be paid	$ 90,000

License and Collaboration Agr83

License and Collaboration Agreements - Technology Licenses (Details) - License Agreement - AstraZeneca UK Limited $ in Millions	1 Months Ended	63 Months Ended
	Oct. 31, 2012USD ($)item	Dec. 31, 2017USD ($)
License Agreements
Number of agreements | item	2
Up-front fees paid	$ 0.4
Payments for milestones achieved		$ 1.5

License and Collaboration Agr84

License and Collaboration Agreements - Merck Collaboration (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
License Agreements
Research and development expense	$ 97,832	$ 73,388	$ 71,400	$ 66,122	$ 71,514	$ 60,783	$ 50,138	$ 52,709	$ 308,742	$ 235,144	$ 155,390
Merck Sharp & Dohme B.V.
License Agreements
Research and development expense									8,400
Amount of research and development costs that are reimbursable									4,100
Other current assets | Merck Sharp & Dohme B.V.
License Agreements
Cost-sharing receivable	$ 1,300								$ 1,300

License and Collaboration Agr85

License and Collaboration Agreements - Takeda Pharmaceutical (Details) $ in Thousands

Jul. 27, 2017USD ($)item

Dec. 31, 2017USD ($)

Sep. 30, 2017USD ($)

Jun. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Sep. 30, 2016USD ($)

Jun. 30, 2016USD ($)

Mar. 31, 2016USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

License Agreements

Upfront payment received

$ 653

Transaction price recognized

$ 48,023

$ 142,766

$ 29,464

$ 3,073

$ 4,921

$ 16,987

$ 35,810

$ 300

$ 223,326

$ 58,018

$ 4,038

License Agreement | Achievement of clinical development and regulatory milestones | Takeda Pharmaceutical Co. Ltd

License Agreements

Number of milestones included in transaction price | item

0

License Agreement | Up-front Payment Arrangement | Takeda Pharmaceutical Co. Ltd

License Agreements

Upfront payment received

$ 100,000

Maximum | License Agreement | Achievement of clinical development and regulatory milestones | Takeda Pharmaceutical Co. Ltd

License Agreements

Potential milestone payments

140,000

Maximum | License Agreement | Achievement of sales milestones | Takeda Pharmaceutical Co. Ltd

License Agreements

Potential milestone payments

$ 100,000

Licenses, collaboration and other revenues | License Agreement | Takeda Pharmaceutical Co. Ltd

License Agreements

Transaction price recognized

$ 100,000

Licence and Collaboration Agree

Licence and Collaboration Agreements - Janssen Biotech Inc (Details) $ in Thousands

Apr. 05, 2017

Apr. 05, 2016USD ($)item

Dec. 31, 2017USD ($)

Sep. 30, 2017USD ($)

Jun. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Sep. 30, 2016USD ($)

Jun. 30, 2016USD ($)

Mar. 31, 2016USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Dec. 31, 2017USD ($)

License Agreements

Upfront payment received

$ 653

Transaction price recognized

$ 48,023

$ 142,766

$ 29,464

$ 3,073

$ 4,921

$ 16,987

$ 35,810

$ 300

$ 223,326

58,018

$ 4,038

Joint Committee performance obligation arrangement

License Agreements

Period over which performance obligation will be recognized as revenue

39 months

Collaborative Arrangement | Janssen Biotech, Inc.

License Agreements

Number Of Days To Provide Electronic Copies Of Certain Know How Relating To Development Of Product

30 days

Prior written notice to terminate programs

90 days

Transaction price

$ 35,000

Number of milestones included in transaction price | item

0

Threshold period within which transaction price is recognized as revenue after entering into collaboration agreement

30 days

Collaborative Arrangement | Licenses, collaboration and other revenues | Janssen Biotech, Inc.

License Agreements

Transaction price recognized

$ 34,700

Collaborative Arrangement | Maximum | Achievement of clinical milestones | Janssen Biotech, Inc.

License Agreements

Potential milestone payments

$ 43,000

Collaborative Arrangement | Maximum | Achievement of regulatory and sales milestones | Janssen Biotech, Inc.

License Agreements

Potential milestone payments

372,000

Collaborative Arrangement | Up-front Payment Arrangement | Janssen Biotech, Inc.

License Agreements

Upfront payment received

$ 35,000

Collaborative Arrangement | License Arrangement | Janssen Biotech, Inc.

License Agreements

Transaction price recognized

34,500

Collaborative Arrangement | Joint Committee performance obligation arrangement | Janssen Biotech, Inc.

License Agreements

Transaction price recognized

$ 500

Period for recognizing performance obligation

5 years

Collaborative Arrangement | Joint Committee performance obligation arrangement | Deferred Revenue [Member]

License Agreements

Remaining amount of performance obligation

$ 300

$ 300

$ 300

Manufacturing supply services | Collaborative Arrangement | Licenses, collaboration and other revenues | Janssen Biotech, Inc.

License Agreements

Other revenue

$ 2,500

$ 1,800

License and Collaboration Agr87

License and Collaboration Agreements - Zai Lab (Shanghai) Co Ltd (Details) $ in Thousands

Sep. 28, 2016item

Dec. 31, 2017USD ($)

Sep. 30, 2017USD ($)

Jun. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Dec. 31, 2016USD ($)

Sep. 30, 2016USD ($)

Jun. 30, 2016USD ($)

Mar. 31, 2016USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

License Agreements

Upfront payment received

$ 653

Transaction price recognized

$ 48,023

$ 142,766

$ 29,464

$ 3,073

$ 4,921

$ 16,987

$ 35,810

$ 300

$ 223,326

$ 58,018

$ 4,038

Collaboration Development And License Agreement | Zai Lab (Shanghai) Co. Ltd.

License Agreements

Number Of Novel Discovery Stage Immuno Oncology Programs Under Option To Negotiate Licenses | item

2

Number of milestones included in transaction price | item

0

Expiration period of collaborative arrangement

10 years

Licenses Revenue

$ 0

Collaboration Development And License Agreement | Technical assistance performance service | Zai Lab (Shanghai) Co. Ltd.

License Agreements

Licenses Revenue

$ 200

Collaboration Development And License Agreement | Manufacturing supply services | Zai Lab (Shanghai) Co. Ltd.

License Agreements

Licenses Revenue

700

Collaboration Development And License Agreement | Up-front Payment Arrangement | Zai Lab (Shanghai) Co. Ltd.

License Agreements

Upfront payment received

$ 15,000

Licenses, collaboration and other revenues | Collaboration Development And License Agreement | Zai Lab (Shanghai) Co. Ltd.

License Agreements

Transaction price recognized

$ 14,800

License and Collaboration Agr88

License and Collaboration Agreements - Jiangsu Hengrui Medicine Co Ltd (Details) $ in Thousands

1 Months Ended

3 Months Ended

12 Months Ended

18 Months Ended

Jul. 31, 2015USD ($)item

Dec. 31, 2017USD ($)

Sep. 30, 2017USD ($)

Jun. 30, 2017USD ($)

Mar. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Sep. 30, 2016USD ($)

Jun. 30, 2016USD ($)

Mar. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Sep. 30, 2015USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Dec. 31, 2016USD ($)

License Agreements

Upfront payment received

$ 653

Transaction price recognized

$ 48,023

$ 142,766

$ 29,464

$ 3,073

$ 4,921

$ 16,987

$ 35,810

$ 300

$ 223,326

$ 58,018

$ 4,038

License Agreement | Jiangsu Hengrui Medicine Co., Ltd

License Agreements

Number of performance obligations | item

2

Amount of up-front payment included in transaction price

$ 1,000

License Agreement | Achievement of submission of clinical trial application with China FDA | Jiangsu Hengrui Medicine Co., Ltd

License Agreements

Amount of future regulatory development milestone included in transaction price

1,000

License Agreement | Achievement of regulatory approval from China FDA | Jiangsu Hengrui Medicine Co., Ltd

License Agreements

Potential milestone payments

$ 1,000

License Agreement | Technical assistance performance service | Jiangsu Hengrui Medicine Co., Ltd

License Agreements

Licenses Revenue

$ 100

License Agreement | Up-front Payment Arrangement | Jiangsu Hengrui Medicine Co., Ltd

License Agreements

Upfront payment received

$ 1,000

Licenses, collaboration and other revenues | License Agreement | Jiangsu Hengrui Medicine Co., Ltd

License Agreements

Transaction price recognized

$ 1,900

Segment Information (Details)

Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue	$ 48,023	$ 142,766	$ 29,464	$ 3,073	$ 4,921	$ 16,987	$ 35,810	$ 300	$ 223,326	$ 58,018	$ 4,038
Total property and equipment, net	9,652				6,640				9,652	6,640
United States
Revenue									221,955	58,018	4,038
Total property and equipment, net	8,583				6,194				8,583	6,194
Europe
Revenue									1,371
Switzerland
Total property and equipment, net	669				446				669	$ 446
Germany
Total property and equipment, net	119								119
Spain
Total property and equipment, net	281								$ 281
Janssen Biotech, Inc. | Revenue
Concentration Risk, Percentage										63.00%
Janssen Biotech, Inc. | Accounts receivable
Concentration Risk, Percentage										26.00%
Zai Lab (Shanghai) Co. Ltd. | Revenue
Concentration Risk, Percentage										27.00%
Zai Lab (Shanghai) Co. Ltd. | Accounts receivable
Concentration Risk, Percentage										11.00%
Takeda Pharmaceutical Co. Ltd | Revenue
Concentration Risk, Percentage									45.00%
Jiangsu Hengrui Medicine Co., Ltd | Accounts receivable
Concentration Risk, Percentage										10.00%
Distributor "A" | Revenue
Concentration Risk, Percentage									32.00%
Distributor "A" | Accounts receivable
Concentration Risk, Percentage									31.00%	42.00%
Distributor "B" | Revenue
Concentration Risk, Percentage									11.00%
Distributor "B" | Accounts receivable
Concentration Risk, Percentage									49.00%
Product revenue
Revenue	$ 47,977	$ 41,755	$ 28,829	$ 2,139	$ 2,330	$ 1,326	$ 1,242	$ 276	$ 120,700	$ 5,174	2,026
ZEJULA
Revenue									108,756
VARUBI/VARUBY
Revenue									$ 11,944	$ 5,174	$ 2,026

Consolidated Quarterly Financ90

Consolidated Quarterly Financial Data - Unaudited (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenue	$ 48,023	$ 142,766	$ 29,464	$ 3,073	$ 4,921	$ 16,987	$ 35,810	$ 300	$ 223,326	$ 58,018	$ 4,038
Cost of sales - product	30,857	6,216	3,620	444	512	378	234	79	41,137	1,203	62
Cost of sales - intangible asset amortization	1,435	1,254	2,979	490	464	464	463	464	6,158	1,855	268
Research and development	97,832	73,388	71,400	66,122	71,514	60,783	50,138	52,709	308,742	235,144	155,390
Selling, general and administrative	90,569	83,998	92,979	69,262	54,526	37,685	36,218	30,149	336,808	158,578	78,701
Acquired in-process research and development expense	3,000		7,000		9,000	1,940	4,000	4,000	10,000	18,940	2,000
Total expenses	223,693	164,856	177,978	136,318	136,016	101,250	91,053	87,401	702,845	415,720	236,421
Loss from operations	175,670	22,090	148,514	133,245	131,095	84,263	55,243	87,101	479,519	357,702	232,383
Interest expense	(6,641)	(4,424)	(4,426)	(4,267)	(4,267)	(4,119)	(4,120)	(3,981)	(19,758)	(16,487)	(15,414)
Interest income	1,214	1,133	959	841	597	532	209	102	4,147	1,440	48
Other income	85	243							328
(Loss) income before provision for -benefit from income taxes	(181,012)	(25,138)	(151,981)	(136,671)	(134,765)	(87,850)	(59,154)	(90,980)	(494,802)	(372,749)	(247,749)
Income Tax Expense (Benefit)	1,053	139	78	54	1,475				1,324	1,475
Net loss	$ (182,065)	$ (25,277)	$ (152,059)	$ (136,725)	$ (136,240)	$ (87,850)	$ (59,154)	$ (90,980)	$ (496,126)	$ (374,224)	$ (247,749)
Net loss per share applicable to common stockholders - basic and diluted (in dollars per share)	$ (3.35)	$ (0.47)	$ (2.82)	$ (2.55)	$ (2.59)	$ (1.72)	$ (1.29)	$ (2.22)	$ (9.17)	$ (7.85)	$ (6.29)
Weighted-average number of common shares used in net loss per share applicable to common stockholders - basic and diluted (in shares)	54,403	54,241	53,982	53,685	52,589	51,151	45,808	40,966	54,080	47,652	39,387
Inventory write-downs									$ 16,730
Write Down Due To Loss On Firm Purchase Commitments
Inventory write-downs	$ 1,600								1,600
ASU No. 2016-09 | New Accounting Pronouncement Early Adoption Effect
Research and development								$ 100
Selling, general and administrative								100
Anaptys Bio Inc
Acquired in-process research and development expenses that relate to licensing agreement expenses	3,000		$ 7,000			$ 1,000	$ 4,000	4,000
Merck Sharp & Dohme B.V.
Research and development									8,400
Acquired in-process research and development expenses that relate to licensing agreement expenses					$ 9,000	900
Janssen Biotech, Inc.
Proceeds from License Fees Received							35,000
Zai Lab (Shanghai) Co. Ltd.
Proceeds from License Fees Received						15,000
Product revenue
Revenue	47,977	$ 41,755	28,829	$ 2,139	2,330	1,326	1,242	276	120,700	$ 5,174	$ 2,026
Licenses, collaboration and other revenues
Revenue	46	101,011	$ 635	$ 934	$ 2,591	15,661	$ 34,568	$ 24	102,626	52,844	2,012
Licenses, collaboration and other revenues | Zai Lab (Shanghai) Co. Ltd.
Revenue						$ 14,800
Licenses, collaboration and other revenues | Takeda Pharmaceutical Co. Ltd
Revenue		$ 100,000
VARUBI/VARUBY
Revenue									11,944	$ 5,174	$ 2,026
Cost of sales - product									2,000
VARUBI/VARUBY | Write Down To Lower Of Cost Or Market
Inventory write-downs	$ 16,700								$ 16,700

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Product Sales Allowances [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 1,489	$ 1,235
Charges to Net Product Revenues	33,884	4,172	$ 1,235
Credits or Payments Made	(26,835)	(3,918)
Balance at End of Year	8,538	1,489	1,235
Returns
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	18	8
Charges to Net Product Revenues	16,338	10	8
Credits or Payments Made	(6)
Balance at End of Year	$ 16,350	$ 18	$ 8