Infinity Pharmaceuticals (INFIQ) 10-Q 6 May 14 2014 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2014	Apr. 21, 2014
Document Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	31-Mar-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q1	'
Trading Symbol	'INFI	'
Entity Registrant Name	'INFINITY PHARMACEUTICALS, INC.	'
Entity Central Index Key	'0001113148	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	48,542,517

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Assets	'	'
Cash and cash equivalents	$54,971	$68,114
Available-for-sale securities	116,560	145,772
Loan commitment asset, net (note 8)	10,655	'
Prepaid expenses and other current assets	12,064	11,055
Total current assets	194,250	224,941
Property and equipment, net	3,748	4,010
Long-term available-for-sale securities	565	582
Restricted cash	1,130	1,130
Other assets	88	47
Total assets	199,781	230,710
Liabilities and stockholders' equity	'	'
Accounts payable	5,852	6,375
Accrued expenses	13,763	9,164
Due to Millennium, current	6,508	6,667
Total current liabilities	26,123	22,206
Due to Millennium, less current portion	'	6,456
Other liabilities	605	773
Total liabilities	26,728	29,435
Commitments and contingencies	'	'
Stockholders' equity:	'	'
Preferred Stock, $0.001 par value; 1,000,000 shares authorized, no shares issued and outstanding at March 31, 2014 and December 31, 2013	'	'
Common Stock, $0.001 par value; 100,000,000 shares authorized, and 48,518,382 and 48,227,838 shares issued and outstanding, at March 31, 2014 and December 31, 2013, respectively	48	48
Additional paid-in capital	664,912	650,867
Accumulated deficit	-492,062	-449,796
Accumulated other comprehensive income	155	156
Total stockholders' equity	173,053	201,275
Total liabilities and stockholders' equity	$199,781	$230,710

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2014	Dec. 31, 2013
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common Stock, par value	$0.00	$0.00
Common Stock, shares authorized	100,000,000	100,000,000
Common Stock, shares issued	48,518,382	48,227,838
Common Stock, shares outstanding	48,518,382	48,227,838

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations and Comprehensive Loss (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Operating expenses:	'	'
Research and development	$34,491	$20,231
General and administrative	6,804	7,430
Total operating expenses	41,295	27,661
Loss from operations	-41,295	-27,661
Other income (expense):	'	'
Interest expense	-1,139	'
Investment and other income	168	335
Total other income (expense)	-971	335
Net (loss) income	-42,266	-27,326
Basic and diluted loss per common share	($0.87)	($0.57)
Basic and diluted weighted average number of common shares outstanding	48,348,767	47,620,147
Other comprehensive income (loss):	'	'
Net unrealized holding gains (losses) on available-for-sale securities arising during the period	-1	17
Comprehensive loss	($42,267)	($27,309)

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Operating activities	'	'
Net loss	($42,266)	($27,326)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Depreciation	468	442
Stock-based compensation including 401(k) match	3,744	3,992
Net amortization of premium/discount on available-for-sale securities	592	393
Non-cash interest expense on Due to Millennium amount	52	'
Amortization of loan commitment asset	1,139	'
Other, net	-30	102
Changes in operating assets and liabilities:	'	'
Prepaid expenses and other assets	-1,050	-1,474
Accounts payable, accrued expenses and other liabilities	463	-1,429
Due to Millennium	-6,667	'
Net cash used in operating activities	-43,555	-25,300
Investing activities	'	'
Purchases of property and equipment	-176	-287
Purchases of available-for-sale securities	-12,536	-91,829
Proceeds from maturities of available-for-sale securities	41,172	40,340
Net cash provided by (used in) investing activities	28,460	-51,776
Financing activities	'	'
Proceeds from issuances of common stock related to stock incentive plans	1,952	2,476
Net cash provided by financing activities	1,952	2,476
Net decrease in cash and cash equivalents	-13,143	-74,600
Cash and cash equivalents at beginning of period	68,114	175,742
Cash and cash equivalents at end of period	54,971	101,142
Supplemental schedule of noncash investing and financing activities	'	'
Loan commitment asset	11,350	'
Facility fee	3,000	'
Warrants issued	$8,350	'

Organization

Organization	3 Months Ended
	Mar. 31, 2014
Organization	'
	1. Organization
	Infinity Pharmaceuticals, Inc. is an innovative biopharmaceutical company dedicated to discovering, developing and delivering best-in-class medicines to patients with difficult-to-treat diseases. As used throughout these unaudited, condensed consolidated financial statements, the terms “Infinity,” “we,” “us,” and “our” refer to the business of Infinity Pharmaceuticals, Inc. and its wholly owned subsidiaries.

Basis_of_Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2014
Basis of Presentation	'
	2. Basis of Presentation
	These condensed consolidated financial statements include the accounts of Infinity and its wholly owned subsidiaries. We have eliminated all significant intercompany accounts and transactions in consolidation.
	The accompanying condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring accruals and revisions of estimates, considered necessary for a fair presentation of the accompanying condensed consolidated financial statements have been included. Interim results for the three months ended March 31, 2014 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2014.
	The information presented in the condensed consolidated financial statements and related footnotes at March 31, 2014, and for the three months ended March 31, 2014 and 2013, is unaudited, and the condensed consolidated balance sheet amounts and related footnotes at December 31, 2013 have been derived from our audited financial statements. For further information, please refer to the consolidated financial statements and accompanying footnotes included in our annual report on Form 10-K for the fiscal year ended December 31, 2013, which was filed with the U.S. Securities and Exchange Commission on February 25, 2014.

Significant_Accounting_Policie

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2014
Significant Accounting Policies	'
	3. Significant Accounting Policies
	Cash Equivalents and Available-For-Sale Securities
	Cash equivalents and available-for-sale securities primarily consist of money market funds, U.S. government-sponsored enterprise obligations, corporate obligations and mortgage-backed securities. Corporate obligations include obligations issued by corporations in countries other than the United States, including some obligations that have not been guaranteed by governments or government agencies. We consider all highly liquid investments with maturities of three months or less at the time of purchase to be cash equivalents. Cash equivalents, which consist of money market funds and corporate obligations, are stated at fair value. They are also readily convertible to known amounts of cash and have such short-term maturities that each presents insignificant risk of change in value due to changes in interest rates. Our classification of cash equivalents is consistent with prior periods.
	We determine the appropriate classification of marketable securities at the time of purchase and reevaluate such designation at each balance sheet date. We have classified all of our marketable securities at March 31, 2014 and December 31, 2013 as “available-for-sale.” We carry available-for-sale securities at fair value, with the unrealized gains and losses reported in accumulated other comprehensive income, which is a separate component of stockholders’ equity.
	We adjust the cost of available-for-sale debt securities for amortization of premiums and accretion of discounts to maturity. We include such amortization and accretion in investment and other income. The cost of securities sold is based on the specific identification method. We include in investment and other income interest and dividends on securities classified as available-for-sale.
	We conduct periodic reviews to identify and evaluate each investment that is in an unrealized loss position in order to determine whether an other-than-temporary impairment exists. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. Unrealized losses on available-for-sale debt securities that are determined to be temporary, and not related to credit loss, are recorded, net of tax, in accumulated other comprehensive income.
	For available-for-sale debt securities in an unrealized loss position, we perform an analysis to assess whether we intend to sell or whether we would more likely than not be required to sell the security before the expected recovery of the amortized cost basis. Where we intend to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary, and the full amount of the unrealized loss is recorded within earnings as an impairment loss.
	Regardless of our intent to sell a security, we perform additional analysis on all securities in an unrealized loss position to evaluate losses associated with the creditworthiness of the security. Credit losses are identified where we do not expect to receive cash flows sufficient to recover the amortized cost basis of a security and are recorded within earnings as an impairment loss.
	Segment Information
	We operate in one business segment, which focuses on drug discovery and development. We make operating decisions based upon performance of the enterprise as a whole and utilize our consolidated financial statements for decision making.
	All of our revenues to date have been generated under research collaboration agreements.
	Basic and Diluted Net Loss per Common Share
	Basic net loss per share is based upon the weighted average number of common shares outstanding during the period. Diluted net loss per share is based upon the weighted average number of common shares outstanding during the period plus the effect of additional weighted average common equivalent shares outstanding during the period when the effect of adding such shares is dilutive. Common equivalent shares result from the assumed exercise of outstanding stock options (the proceeds of which are then assumed to have been used to repurchase outstanding stock using the treasury stock method) and the exercise of outstanding warrants. In addition, the assumed proceeds under the treasury stock method include the average unrecognized compensation expense of stock options that are in-the-money. This results in the “assumed” buyback of additional shares, thereby reducing the dilutive impact of stock options. Common equivalent shares have not been included in the net loss per share calculations for the periods presented because the effect of including them would have been anti-dilutive. Total potential gross common equivalent shares consisted of the following:
			At March 31,
			2014		2013
	Stock options			6,772,555		6,241,841
	Warrants			1,000,000		—
	Comprehensive Loss
	Comprehensive loss is comprised of net loss and other comprehensive income (loss). Other comprehensive income (loss) is comprised of unrealized holding gains and losses arising during the period on available-for-sale securities that are not other-than-temporarily impaired. During the three months ended March 31, 2014, there were no reclassifications out of accumulated other comprehensive income (loss).
	Stock-Based Compensation Expense
	For awards granted to employees and directors, including our Employee Stock Purchase Plan, or ESPP, we measure stock-based compensation cost at the grant date based on the estimated fair value of the award and recognize it as expense over the requisite service period on a straight-line basis. We record the expense of services rendered by non-employees based on the estimated fair value of the stock option as of the respective vesting date. We use the Black-Scholes valuation model in determining the fair value of all equity awards. For awards with performance conditions, we estimate the likelihood of satisfaction of the performance conditions, which affects the period over which the expense is recognized, and recognize the expense over the requisite service period on a straight-line basis. We have no awards with market conditions.
	Revenue Recognition
	To date, all of our revenue has been generated under research collaboration agreements. The terms of these research collaboration agreements may include payment to us of non-refundable, up-front license fees, funding or reimbursement of research and development efforts, milestone payments if specified objectives are achieved, and/or royalties on product sales. We recognize revenue based upon our best estimate of the selling price for an undelivered item when there is no other means to determine the fair value of that undelivered item.
	At the inception of each agreement that includes milestone payments, we evaluate whether each milestone is substantive on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether:
		•		the consideration is commensurate with either (1) our performance to achieve the milestone, or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from our performance to achieve the milestone,
		•		the consideration relates solely to past performance, and
		•		the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement.
	In making this assessment, we evaluate factors such as the clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required, and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement. We recognize revenues related to substantive milestones in full in the period in which the substantive milestone is achieved. If a milestone payment is not considered substantive, we recognize the applicable milestone over the remaining period of performance.
	We will recognize royalty revenue, if any, based upon actual and estimated net sales by the licensee of licensed products in licensed territories, and in the period the sales occur. We have not recognized any royalty revenue to date.
	Research and Development Expense
	Research and development expense consists of expenses incurred in performing research and development activities, including salaries and benefits, overhead expenses including facilities expenses, materials and supplies, preclinical expenses, clinical trial and related clinical manufacturing expenses, comparator drug expenses, stock-based compensation expense, depreciation of equipment, contract services, and other outside expenses. We also include as research and development expense up-front license payments related to acquired technologies which have not yet reached technological feasibility and have no alternative use. We expense research and development costs as they are incurred. We have been a party to collaboration agreements in which we were reimbursed for work performed on behalf of the collaborator, as well as one in which we reimbursed the collaborator for work it had performed. We record all appropriate expenses under our collaborations as research and development expense. If the arrangement provides for reimbursement of research and development expenses, as was the case with our alliance with Mundipharma and Purdue, we record the reimbursement as revenue. If the arrangement provides for us to reimburse the collaborator for research and development expenses or achieving a development milestone for which a payment is due, as was the case with our agreement with Intellikine, Inc., or Intellikine, we record the reimbursement or the achievement of the development milestone as research and development expense. In January 2012, Intellikine was acquired by Takeda Pharmaceutical Company Limited, or Takeda, acting through its Millennium business unit. We refer to our PI3K program licensor as Millennium.
	Income Taxes
	We use the liability method to account for income taxes. Deferred tax assets and liabilities are determined based on temporary differences between financial reporting and income tax basis of assets and liabilities, as well as net operating loss and tax credit carryforwards, and are measured using the enacted tax rates and laws that will be in effect when the differences reverse. Deferred tax assets are reduced by a valuation allowance to reflect the uncertainty associated with their ultimate realization. The effect of a change in tax rate on deferred taxes is recognized in income or loss in the period that includes the enactment date.
	We use our judgment for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. We recognize any material interest and penalties related to unrecognized tax benefits in income tax expense.
	Due to the uncertainty surrounding the realization of the net deferred tax assets in future periods, we have recorded a full valuation allowance against our otherwise recognizable net deferred tax assets as of March 31, 2014 and December 31, 2013.
	Fair Value Measurements
	We define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We determine fair value based on the assumptions market participants use when pricing the asset or liability. We also use the fair value hierarchy that prioritizes the information used to develop these assumptions.
	We value our available-for-sale securities utilizing third party pricing services. The pricing services use many observable market inputs to determine value, including benchmark yields, reportable trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data, new issue data, monthly payment information and collateral performance. We validate the prices provided by our third party pricing services by understanding the models used, obtaining market values from other pricing sources, and confirming that those securities trade in active markets. We value the balance of the release payment due to Millennium based on a discounted cash flow model.
	Property and Equipment
	Property and equipment are stated at cost. Depreciation is recorded using the straight-line method over the estimated useful lives of the applicable assets. Application development costs incurred for computer software developed or obtained for internal use are capitalized. Upon sale or retirement, the cost and related accumulated depreciation are eliminated from the respective account and the resulting gain or loss, if any, is included in current operations. Amortization of leasehold improvements and capital leases is recorded as depreciation expense and included in research and development and general and administrative expense. Repairs and maintenance charges that do not increase the useful life of the assets are charged to operations as incurred. Property and equipment are depreciated over the following periods:
	Laboratory equipment		5 years
	Computer equipment and software		3 to 5 years
	Leasehold improvements		Shorter of lease term or useful life of asset
	Furniture and fixtures		7 years

StockBased_Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2014
Stock-Based Compensation	'
	4. Stock-Based Compensation
	Total stock-based compensation expense related to all equity awards for the three months ended March 31, 2014 and 2013 comprised the following:
		Three Months Ended			Three Months Ended
		31-Mar-14			March 31, 2013
		(in thousands)
	Effect of stock-based compensation on net loss by line item:
	Research and development	$	2,205		$	1,542
	General and administrative		1,539			2,450
	As of March 31, 2014, we had approximately $23.6 million of total unrecognized compensation cost, net of estimated forfeitures, related to unvested stock options and awards under our ESPP, which are expected to be recognized over a weighted-average period of 2.8 years.
	During the three months ended March 31, 2014, two members of our board of directors retired and were granted the right to exercise their vested stock options for an additional six-month period. In addition, one employee whose employment terminated received an accelerated vesting of his unvested options. In connection with these modifications, we recognized an additional $0.4 million in stock-based compensation expense during the three months ended March 31, 2014.
	Stock Options
	During the three months ended March 31, 2014, we granted options to purchase 1,152,884 shares of our common stock at a weighted average fair value of $7.79 and a weighted average exercise price of $13.13. During the three months ended March 31, 2013, we granted options to purchase 986,094 shares of our common stock at a weighted average fair value of $20.44 and a weighted average exercise price of $37.33. For the three months ended March 31, 2014 and 2013, the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions:
		Three Months Ended			Three Months Ended
		31-Mar-14			March 31, 2013
	Risk-free interest rate		1.7	%		0.8	%
	Expected annual dividend yield		—			—
	Expected stock price volatility		71.1	%		60.4	%
	Expected term of options		5.1 years			5.0 years
	During the three months ended March 31, 2014, options to purchase 280,772 shares of common stock were exercised, with a weighted-average exercise price of $6.95.
	Employee Stock Purchase Plan
	The weighted-average fair value of each purchase right granted during the three months ended March 31, 2014 was $6.33. For the three months ended March 31, 2014, the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions:
		Three Months Ended
		31-Mar-14
	Risk-free interest rate		0.2	%
	Expected annual dividend yield		—
	Expected stock price volatility		75.21	%
	Expected term of options		1.2 years

Cash_Cash_Equivalents_and_Avai

Cash, Cash Equivalents and Available-for-Sale Securities	3 Months Ended
	Mar. 31, 2014
Cash, Cash Equivalents and Available-for-Sale Securities	'
	5. Cash, Cash Equivalents and Available-for-Sale Securities
	The following is a summary of cash, cash equivalents and available-for-sale securities:
		March 31, 2014
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	54,971	$	—	$	—		$	54,971
	Available-for-sale securities:
	Corporate obligations due in one year or less		78,107		32		(9	)		78,130
	Corporate obligations due in one to five years		10,162		18		—			10,180
	Mortgage-backed securities due after ten years		461		104		—			565
	U.S. government-sponsored enterprise obligations due in one year or less		28,240		12		(2	)		28,250
	Total available-for-sale securities		116,970		166		(11	)		117,125
	Total cash, cash equivalents and available-for-sale securities	$	171,941	$	166	$	(11	)	$	172,096
		December 31, 2013
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	68,114	$	—	$	—		$	68,114
	Available-for-sale securities:
	Corporate obligations due in one year or less		103,889		18		(16	)		103,891
	Corporate obligations due in one to five years		13,513		32		—			13,545
	Mortgage-backed securities due after ten years		478		104		—			582
	U.S. government-sponsored enterprise obligations due in one year or less		24,144		13		—			24,157
	U.S. government-sponsored enterprise obligations due in one to five years		4,174		5		—			4,179
	Total available-for-sale securities		146,198		172		(16	)		146,354
	Total cash, cash equivalents and available-for-sale securities	$	214,312	$	172	$	(16	)	$	214,468
	We held 17 debt securities at March 31, 2014 that had been in an unrealized loss position for less than 12 months and no debt securities that had been in an unrealized loss position for 12 months or greater. The fair value on these securities was $43.6 million. We evaluated our securities for other-than-temporary impairments based on quantitative and qualitative factors. We considered the decline in market value for these 17 securities to be primarily attributable to current economic and market conditions. It is not more likely than not that we will be required to sell these securities, and we do not intend to sell these securities before the recovery of their amortized cost bases. Based on our analysis, we do not consider these investments to be other-than-temporarily impaired as of March 31, 2014.
	As of March 31, 2014, we held 13 debt securities from financial institutions and other companies located in the United Kingdom, the Netherlands, Japan, Switzerland, Australia and France with a fair value of $41 million. Seven of these securities, which were issued by the Netherlands, Japan, France and the United Kingdom, had gross unrealized losses of $3,000 and a fair value of $14.3 million. These securities are short term in nature and are scheduled to mature research within 12 months. Based on our analysis, we do not consider these investments to be other-than-temporarily impaired as of March 31, 2014.
	We had no material realized gains or losses on our available-for-sale securities for the three months ended March 31, 2014 and 2013. There were no other-than-temporary impairments recognized for the three months ended March 31, 2014 and 2013.

Fair_Value

Fair Value	3 Months Ended
	Mar. 31, 2014
Fair Value	'
	6. Fair Value
	We use a valuation hierarchy for disclosure of the inputs used to measure fair value. This hierarchy prioritizes the inputs into three broad levels. Level 1 inputs, which we consider the highest level inputs, are quoted prices (unadjusted) in active markets for identical assets or liabilities. Level 2 inputs are quoted prices for similar assets and liabilities in active markets or inputs that are observable for the asset or liability, either directly or indirectly through market corroboration, for substantially the full term of the financial instrument. Level 3 inputs are unobservable inputs based on our own assumptions used to measure assets and liabilities at fair value. The classification of a financial asset or liability within the hierarchy is determined based on the lowest level input that is significant to the fair value measurement. For our fixed income securities, we reference pricing data supplied by our custodial agent and nationally known pricing vendors, using a variety of daily data sources, largely readily-available market data and broker quotes. We validate the prices provided by our third party pricing services by reviewing their pricing methods and obtaining market values from other pricing sources. After completing our validation procedures, we did not adjust or override any fair value measurements provided by our pricing services as of March 31, 2014 and December 31, 2013.
	The following table provides the assets carried at fair value measured on a recurring basis as of March 31, 2014:
			Level 1		Level 2
			(in thousands)
	Assets:
	Cash and cash equivalents		$	54,971	$	—
	Corporate obligations (including commercial paper)			—		88,310
	Mortgage-backed securities			—		565
	U.S. government-sponsored enterprise obligations			—		28,250
	Total		$	54,971	$	117,125
	The fair value of the available-for-sale securities and cash and cash equivalents (including asset types listed below with maturities of three months or less at the time of purchase) is based on the following inputs:
		•		Corporate Obligations:
		•		Commercial paper: calculations by custodian based on the three month Treasury bill published on the last business day of the month.
		•		Other: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data.
		•		Mortgage-Backed Securities: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data, new issue data, monthly payment information and collateral performance.
		•		U.S. Government-Sponsored Enterprise Obligations: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers and reference data.
	The amount due to Millennium is recorded at its carrying value at March 31, 2014. The fair value of the amount due to Millennium, a Level 2 measurement, was approximately $6.6 million as of March 31, 2014 and was determined using a discounted cash flow model and based on an interest rate we would be charged for a similar loan as of March 31, 2014 (see note 7).
	The carrying amounts reflected in the condensed consolidated balance sheets for prepaid expenses and other current assets, other assets, accounts payable and accrued expenses approximate their fair value due to their short term maturities.
	There have been no changes to the valuation methods during the three months ended March 31, 2014. We evaluate transfers between levels at the end of each reporting period. There were no transfers of assets or liabilities between Level 1 and Level 2 during the three months ended March 31, 2014. We had no available-for-sale securities that were classified as Level 3 at any point during the three months ended March 31, 2014 or during the year ended December 31, 2013.

Collaborations

Collaborations	3 Months Ended
	Mar. 31, 2014
Collaborations	'
	7. Collaborations
	Millennium
	In July 2010, we entered into a development and license agreement with Intellikine under which we obtained rights to discover, develop and commercialize pharmaceutical products targeting the delta and/or gamma isoforms of PI3K, including IPI-145, and we paid Intellikine a $13.5 million up-front license fee. In January 2012, Intellikine was acquired by Takeda acting through its Millennium business unit. In December 2012, we amended and restated our development and license agreement with Millennium.
	Under the terms of the amended and restated agreement, we retained worldwide development and commercialization rights for products arising from the agreement for all therapeutic indications, and we are solely responsible for research conducted under the agreement. Additionally, under the amended and restated agreement, Millennium waived certain commercial rights and, in consideration of such waiver, we agreed to pay to Millennium $15 million, payable in installments. During the year ended December 31, 2012, we paid $1.7 million of the $15 million, and we recorded the $15 million release payment at its fair value of $14.4 million in research and development expenses. During the three months ended March 31, 2014, we paid to Millennium the second installment of $6.7 million. The remaining amount is due in January 2015, which we recorded as short-term liability due to Millennium on our condensed consolidated balance sheet.
	In addition to developing IPI-145, we are seeking to develop our second potent, oral PI3K-delta,gamma inhibitor product candidate, IPI-443, and we are seeking to identify additional novel inhibitors of PI3K-delta and/or PI3K-gamma for future development. We are obligated to pay to Millennium up to $5 million in remaining success-based milestone payments for the development of two distinct product candidates, and up to $450 million in success-based milestones for the approval and commercialization of two distinct products. In February 2014, we paid Millennium a $10 million milestone payment in connection with the initiation of our Phase 3 study of IPI-145 in patients with relapsed or refractory CLL. We recognized the $10 million payment as research and development expense during the three months ended March 31, 2014. In addition, we are obligated to pay Millennium tiered royalties on worldwide net sales ranging from 7 percent to 11 percent upon successful commercialization of products described in the agreement. Such royalties are payable until the later to occur of the expiration of specified patent rights and the expiration of non-patent regulatory exclusivities in a country, subject to reduction of the royalties, and limits on the number of products subject to a royalty obligation, in certain circumstances.
	The amended and restated agreement expires on the later of the expiration of certain patents and the expiration of the royalty payment terms for the products, unless earlier terminated. Either party may terminate the agreement on 75 days’ prior written notice if the other party materially breaches the agreement and fails to cure such breach within the applicable notice period, provided that the notice period is reduced to 30 days where the alleged breach is non-payment. Millennium may also terminate the agreement if we are not diligent in developing or commercializing the licensed products and do not, within three months after notice from Millennium, demonstrate to Millennium’s reasonable satisfaction that we have not failed to be diligent. The foregoing periods are subject to extension in certain circumstances. Additionally, Millennium may terminate the agreement upon 30 days’ prior written notice if we or a related party bring an action challenging the validity of any of the licensed patents, provided that we have not withdrawn such action before the end of the 30-day notice period. We may terminate the agreement at any time upon 180 days’ prior written notice. The agreement also provides for customary reciprocal indemnification obligations of the parties.
	Mundipharma and Purdue
	Strategic Alliance Termination Agreements
	On July 17, 2012, we terminated our strategic alliance with Mundipharma International Corporation Limited, or Mundipharma, and Purdue Pharmaceutical Products L.P., or Purdue, and entered into termination and revised relationship agreements with each of those entities, which we refer to as the 2012 Termination Agreements. We considered Mundipharma, Purdue and their respective associated entities to be related parties for financial reporting purposes prior to April 2013 because of their equity ownership in us. The alliance was previously governed by strategic alliance agreements that we entered into with each of Mundipharma and Purdue in November 2008. The strategic alliance agreement with Purdue was focused on the development and commercialization in the United States of products targeting fatty acid amide hydrolase, or FAAH. The strategic alliance agreement with Mundipharma was focused on the development and commercialization outside of the United States of all products and product candidates that inhibit or target the Hedgehog pathway, FAAH, phosphoinositide-3-kinase, or PI3K, and product candidates arising out of our early discovery projects in all disease fields. Our heat shock protein 90, or Hsp90, program was expressly excluded from the alliance.
	Under the terms of the 2012 Termination Agreements:
		•	All intellectual property rights that we had previously licensed to Mundipharma and Purdue to develop and commercialize products under the previous strategic alliance agreements terminated, with the result that we have worldwide rights to all product candidates that had previously been covered by the strategic alliance.
		•	We have no further obligation to provide research and development services to Mundipharma and Purdue as of July 17, 2012.
		•	Mundipharma and Purdue have no further obligation to provide research and development funding to us. Under the alliance, Mundipharma was obligated to reimburse us for research and development expenses we incurred, up to an annual aggregate cap for each alliance program other than FAAH. We did not record a liability for amounts previously funded by Purdue and Mundipharma as this relationship was not considered a financing arrangement.
		•	We are obligated to pay Mundipharma and Purdue a 4 percent royalty in the aggregate, subject to reduction as described below, on worldwide net sales of products that were covered by the alliance until such time as they have recovered approximately $260 million, representing the research and development funding paid to us for research and development services performed by us through the termination of the strategic alliance. After this cost recovery, our royalty obligations to Mundipharma and Purdue will be reduced to a one percent royalty on net sales in the United States of products that were previously subject to the strategic alliance. All payments are contingent upon the successful commercialization of products subject to the alliance, which products are subject to significant further development. As such, there is significant uncertainty about whether any such products will ever be approved or commercialized. If no products are commercialized, no payments will be due by us to Mundipharma and Purdue; therefore, no amounts have been accrued.
	Royalties are payable under these agreements until the later to occur of the last-to-expire of specified patent rights and the expiration of non-patent regulatory exclusivities in a country, provided that if royalties are payable solely on the basis of non-patent regulatory exclusivity, each of the royalty rates is reduced by 50 percent. In addition, royalties payable under these agreements after Mundipharma and Purdue have recovered all research and development expenses paid to us are subject to reduction on account of third party royalty payments or patent litigation damages or settlements which might be required to be paid by us if litigation were to arise, with any such reductions capped at 50 percent of the amounts otherwise payable during the applicable royalty payment period.
	Line of Credit Agreement
	In connection with the previous strategic alliance with Mundipharma and Purdue, we also entered into a line of credit agreement with Purdue and its independent associated company, Purdue Pharma L.P., or PPLP, that provided for the borrowing by us of one or more unsecured loans up to an aggregate maximum principal amount of $50 million. On September 7, 2012, upon completion of the sale and issuance of common stock to PPLP under the 2012 Securities Purchase Agreement described below, the line of credit agreement with PPLP terminated in its entirety.
	2012 Securities Purchase Agreement
	On July 17, 2012, in connection with the termination of the strategic alliance with Mundipharma and Purdue, we executed a securities purchase agreement with PPLP, which we refer to as the 2012 Securities Purchase Agreement, under which we agreed to sell and issue 5,416,565 shares of our common stock to PPLP and two entities associated with PPLP, which we collectively refer to as the BRP entities, at a price of $14.50 per share for an aggregate consideration of approximately $78.5 million and, in connection therewith, to grant various rights to the BRP entities. The consideration was composed of extinguishment of approximately $51 million in principal and interest owed to PPLP under a line of credit agreement and $27.5 million in cash. We completed the sale and issuance on September 7, 2012 at which time the line of credit agreement with PPLP terminated in its entirety. The 2012 Securities Purchase Agreement terminated in its entirety.
	April 2013 Offering and 2013 Termination Agreement
	On April 16, 2013, the BRP entities, through two selling stockholders, sold 11,416,565 shares in an underwritten public offering at a price of $40 per share, representing their entire holdings in our common stock. In connection with the public offering and sale of their common stock, we entered into an agreement with the BRP entities, pursuant to which the 2012 Securities Purchase Agreement, as amended in connection with the offering, terminated in its entirety. Following the closing of the offering, the BRP entities no longer owned any shares of our common stock at such time, and, as such, are no longer related parties.

Debt_Facility_Agreement

Debt Facility Agreement	3 Months Ended
	Mar. 31, 2014
Debt Facility Agreement	'
	8. Debt Facility Agreement
	Facility Agreement
	On February 24, 2014, we entered into a facility agreement with affiliates of Deerfield Management Company, L.P., or Deerfield, which we refer to as the Facility Agreement. Pursuant to the Facility Agreement, Deerfield agreed to loan us up to $100 million, subject to the terms and conditions set forth in the Facility Agreement. Under the terms of the Facility Agreement, we may draw down on the Facility Agreement in $25 million minimum disbursements, which we refer to as the Loan Commitment, at any time until February 27, 2015, which we will refer to as the Draw Period. Our ability to draw down under the Facility Agreement is subject to various customary conditions, including the entry into a guaranty and security agreement , or the Guaranty, with Deerfield and Infinity Discovery, Inc., or IDI, one of our wholly-owned subsidiaries, pursuant to which, as security for the repayment of our obligations under the Facility Agreement, IDI will guaranty all of our obligations under the Facility Agreement. As an additional condition to our initial draw down under the Facility Agreement, both IDI and we will grant to Deerfield a security interest in substantially all of our assets including intellectual property to secure our obligations under the Facility Agreement and the Guaranty. In exchange for the Loan Commitment, on February 24, 2014, we issued to Deerfield warrants to purchase 1,000,000 shares of our common stock at an exercise price of $13.83 per share.
	Any amounts drawn under the Facility Agreement accrue interest at a rate of 7.95 percent per annum, and such interest shall be payable quarterly in arrears on the first day of each June, September, December and March following the disbursement date, provided that, subject to the next sentence, during the first five interest payment dates of any draw under the Facility Agreement, we may elect to pay all or a portion of such accrued interest by adding it to the principal amount outstanding. All such accrued interest will, regardless of which draw it applies to, be payable on the last business day of the sixth calendar quarter following the date of the first draw under the Facility Agreement. We have the right to terminate the Facility Agreement and/or to prepay amounts owed under the Facility Agreement at any time, provided that, to the extent that any amount was drawn less than three years before such early termination or prepayment, we will be required to pay an additional amount equal to three years of interest on the amount being prepaid less the amount of interest previously paid on such amount. For amounts drawn under the Facility Agreement, we will be required to repay them to Deerfield in installments equal to one-third of the outstanding amount of the total principal amount drawn under the Facility Agreement on each of the third, fourth and fifth anniversaries of the first draw; the final payment, however, must be made by December 15, 2019.
	On February 27, 2015, or upon the earlier termination or acceleration of the facility, we are required to pay a fee equal to 3 percent of the difference between the $100 million commitment and the aggregate amount of disbursements under the Facility Agreement made prior to such date, which we refer to as the Facility Fee. As of March 31, 2014, we have not drawn under the Facility Agreement and have determined it probable that we will be required to pay the full Facility Fee amount of $3 million on February 27, 2015. We have recorded the full $3 million Facility Fee on the March 31, 2014 condensed consolidated balance sheet as a component of both the loan commitment asset and accrued expenses line items. The loan commitment asset is being amortized to interest expense in the condensed consolidated statements of operations and comprehensive loss on a straight line basis over the Draw Period.
	Deerfield will have the right to accelerate payment of the facility in the event that we consummate a major transaction, which is generally defined as a change in control, a sale of all or substantially all of our assets, a tender or exchange offer for our common stock, a liquidation, bankruptcy, insolvency, dissolution or wind up, a delisting and/or the common stock ceases to be registered under the Securities Exchange Act of 1934, or the Exchange Act. Any amounts drawn under the Facility Agreement may become immediately due and payable upon (i) customary events of default, as defined in the Facility Agreement, or (ii) the consummation of certain major transactions, in which case Deerfield would have the right to require us to repay 100 percent of the principal amount of the loan, plus any accrued and unpaid interest thereon, plus any applicable additional amounts relating to a prepayment or termination, as described above.
	Principal and interest under the Facility Agreement may be paid in cash or freely tradable shares of common stock at our election, subject to specified conditions at any time of conversion. The Facility Agreement contains various representations and warranties, and affirmative covenants customary for agreements of this type, including the requirement that we maintain at all times a cash, cash equivalents and available-for-sales securities balance of not less than $25 million, as well as negative covenants customary for financings of this type that are applicable upon the first draw under the Facility Agreement. Additionally, the Facility Agreement contains conditions that must be met prior to disbursements, including the condition that the number of shares of our common stock issued or issuable pursuant to all warrants following the proposed disbursement, together with payments made in our common stock under the Facility Agreement, will not exceed 9,500,000 shares.
	Our total cost of securing the Loan Commitment was $11.8 million and is comprised of $8.4 million representing the fair value of the 1,000,000 warrants issued on February 24, 2014, discussed below, $3 million representing the Facility Fee and $0.4 million of transaction costs. The total fair value, a Level 2 measurement, is considered a Loan Commitment Asset which has been classified as a current asset on the March 31, 2014 condensed consolidated balance sheets. This amount is considered a fee to secure the Loan Commitment and is being amortized to interest expense in the March 31, 2014 condensed consolidated statements of operations and comprehensive loss on a straight line basis over the Draw Period. We recorded $1.1 million of interest expense associated with the amortization of the loan commitment asset for the three months ended March 31, 2014.
	Warrants
	In connection with the entry into the Facility Agreement, on February 24, 2014, we issued to Deerfield warrants to purchase 1,000,000 shares of our common stock at an exercise price of $13.83 per share. As of March 31, 2014, all such warrants were outstanding and exercisable. The fair value of the warrants on February 24, 2014, was $8.4 million. The warrants were valued as of February 24, 2014 using a Black Scholes model with the following assumptions: expected life of seven years; risk free rate of 2.2 percent; expected volatility of 59.01 percent; and no expected dividend yield. The warrants qualify for permanent treatment as equity and are classified as additional paid-in capital on the March 31, 2014 condensed consolidated balance sheet.
	With each disbursement made by Deerfield, we have agreed to issue additional warrants to purchase a number of shares of our common stock equal to 50 percent times the quotient of the amount of such disbursement divided by an exercise price equal to the average daily volume weighted average price per share of our common stock for the 20 consecutive trading day period following Deerfield’s receipt of the applicable disbursement request. The maximum number of shares of our common stock issued or issuable pursuant to all warrants and payments made in our common stock under the Facility Agreement is 9,500,000, subject to appropriate adjustment to reflect any stock splits, stock combination, reclassification or similar adjustments in the number of outstanding shares of common stock. The warrants have dividend rights to the same extent as if the warrants were exercised into shares of common stock.
	Each warrant issued under the Facility Agreement expires on the seventh anniversary of its issuance and contains certain limitations that prevent the holder from acquiring shares upon exercise of a warrant that would result in the number of shares beneficially owned by it exceeding 9.985 percent of the total number of shares of common stock then issued and outstanding.

Accrued_Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2014
Accrued Expenses	'
	9. Accrued Expenses
	Accrued expenses consisted of the following:
		March 31,		December 31,
		2014		2013
		(in thousands)
	Accrued compensation and benefits	$	3,169	$	1,839
	Accrued clinical studies		4,114		4,009
	Accrued drug manufacturing costs		1,066		991
	Accrued preclinical studies		268		303
	Facility fee		3,000		—
	Other		2,146		2,022
	Total accrued expenses	$	13,763	$	9,164

Significant_Accounting_Policie1

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2014
Cash Equivalents and Available-For-Sale Securities	'
	Cash Equivalents and Available-For-Sale Securities
	Cash equivalents and available-for-sale securities primarily consist of money market funds, U.S. government-sponsored enterprise obligations, corporate obligations and mortgage-backed securities. Corporate obligations include obligations issued by corporations in countries other than the United States, including some obligations that have not been guaranteed by governments or government agencies. We consider all highly liquid investments with maturities of three months or less at the time of purchase to be cash equivalents. Cash equivalents, which consist of money market funds and corporate obligations, are stated at fair value. They are also readily convertible to known amounts of cash and have such short-term maturities that each presents insignificant risk of change in value due to changes in interest rates. Our classification of cash equivalents is consistent with prior periods.
	We determine the appropriate classification of marketable securities at the time of purchase and reevaluate such designation at each balance sheet date. We have classified all of our marketable securities at March 31, 2014 and December 31, 2013 as “available-for-sale.” We carry available-for-sale securities at fair value, with the unrealized gains and losses reported in accumulated other comprehensive income, which is a separate component of stockholders’ equity.
	We adjust the cost of available-for-sale debt securities for amortization of premiums and accretion of discounts to maturity. We include such amortization and accretion in investment and other income. The cost of securities sold is based on the specific identification method. We include in investment and other income interest and dividends on securities classified as available-for-sale.
	We conduct periodic reviews to identify and evaluate each investment that is in an unrealized loss position in order to determine whether an other-than-temporary impairment exists. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. Unrealized losses on available-for-sale debt securities that are determined to be temporary, and not related to credit loss, are recorded, net of tax, in accumulated other comprehensive income.
	For available-for-sale debt securities in an unrealized loss position, we perform an analysis to assess whether we intend to sell or whether we would more likely than not be required to sell the security before the expected recovery of the amortized cost basis. Where we intend to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary, and the full amount of the unrealized loss is recorded within earnings as an impairment loss.
	Regardless of our intent to sell a security, we perform additional analysis on all securities in an unrealized loss position to evaluate losses associated with the creditworthiness of the security. Credit losses are identified where we do not expect to receive cash flows sufficient to recover the amortized cost basis of a security and are recorded within earnings as an impairment loss.
Segment Information	'
	Segment Information
	We operate in one business segment, which focuses on drug discovery and development. We make operating decisions based upon performance of the enterprise as a whole and utilize our consolidated financial statements for decision making.
	All of our revenues to date have been generated under research collaboration agreements.
Basic and Diluted Net Loss per Common Share	'
	Basic and Diluted Net Loss per Common Share
	Basic net loss per share is based upon the weighted average number of common shares outstanding during the period. Diluted net loss per share is based upon the weighted average number of common shares outstanding during the period plus the effect of additional weighted average common equivalent shares outstanding during the period when the effect of adding such shares is dilutive. Common equivalent shares result from the assumed exercise of outstanding stock options (the proceeds of which are then assumed to have been used to repurchase outstanding stock using the treasury stock method) and the exercise of outstanding warrants. In addition, the assumed proceeds under the treasury stock method include the average unrecognized compensation expense of stock options that are in-the-money. This results in the “assumed” buyback of additional shares, thereby reducing the dilutive impact of stock options. Common equivalent shares have not been included in the net loss per share calculations for the periods presented because the effect of including them would have been anti-dilutive. Total potential gross common equivalent shares consisted of the following:
			At March 31,
			2014		2013
	Stock options			6,772,555		6,241,841
	Warrants			1,000,000		—
Comprehensive Loss	'
	Comprehensive Loss
	Comprehensive loss is comprised of net loss and other comprehensive income (loss). Other comprehensive income (loss) is comprised of unrealized holding gains and losses arising during the period on available-for-sale securities that are not other-than-temporarily impaired. During the three months ended March 31, 2014, there were no reclassifications out of accumulated other comprehensive income (loss).
Stock-Based Compensation Expense	'
	Stock-Based Compensation Expense
	For awards granted to employees and directors, including our Employee Stock Purchase Plan, or ESPP, we measure stock-based compensation cost at the grant date based on the estimated fair value of the award and recognize it as expense over the requisite service period on a straight-line basis. We record the expense of services rendered by non-employees based on the estimated fair value of the stock option as of the respective vesting date. We use the Black-Scholes valuation model in determining the fair value of all equity awards. For awards with performance conditions, we estimate the likelihood of satisfaction of the performance conditions, which affects the period over which the expense is recognized, and recognize the expense over the requisite service period on a straight-line basis. We have no awards with market conditions.
Revenue Recognition	'
	Revenue Recognition
	To date, all of our revenue has been generated under research collaboration agreements. The terms of these research collaboration agreements may include payment to us of non-refundable, up-front license fees, funding or reimbursement of research and development efforts, milestone payments if specified objectives are achieved, and/or royalties on product sales. We recognize revenue based upon our best estimate of the selling price for an undelivered item when there is no other means to determine the fair value of that undelivered item.
	At the inception of each agreement that includes milestone payments, we evaluate whether each milestone is substantive on the basis of the contingent nature of the milestone. This evaluation includes an assessment of whether:
		•		the consideration is commensurate with either (1) our performance to achieve the milestone, or (2) the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from our performance to achieve the milestone,
		•		the consideration relates solely to past performance, and
		•		the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement.
	In making this assessment, we evaluate factors such as the clinical, regulatory, commercial and other risks that must be overcome to achieve the respective milestone, the level of effort and investment required, and whether the milestone consideration is reasonable relative to all deliverables and payment terms in the arrangement. We recognize revenues related to substantive milestones in full in the period in which the substantive milestone is achieved. If a milestone payment is not considered substantive, we recognize the applicable milestone over the remaining period of performance.
	We will recognize royalty revenue, if any, based upon actual and estimated net sales by the licensee of licensed products in licensed territories, and in the period the sales occur. We have not recognized any royalty revenue to date.
Research and Development Expense	'
	Research and Development Expense
	Research and development expense consists of expenses incurred in performing research and development activities, including salaries and benefits, overhead expenses including facilities expenses, materials and supplies, preclinical expenses, clinical trial and related clinical manufacturing expenses, comparator drug expenses, stock-based compensation expense, depreciation of equipment, contract services, and other outside expenses. We also include as research and development expense up-front license payments related to acquired technologies which have not yet reached technological feasibility and have no alternative use. We expense research and development costs as they are incurred. We have been a party to collaboration agreements in which we were reimbursed for work performed on behalf of the collaborator, as well as one in which we reimbursed the collaborator for work it had performed. We record all appropriate expenses under our collaborations as research and development expense. If the arrangement provides for reimbursement of research and development expenses, as was the case with our alliance with Mundipharma and Purdue, we record the reimbursement as revenue. If the arrangement provides for us to reimburse the collaborator for research and development expenses or achieving a development milestone for which a payment is due, as was the case with our agreement with Intellikine, Inc., or Intellikine, we record the reimbursement or the achievement of the development milestone as research and development expense. In January 2012, Intellikine was acquired by Takeda Pharmaceutical Company Limited, or Takeda, acting through its Millennium business unit. We refer to our PI3K program licensor as Millennium.
Income Taxes	'
	Income Taxes
	We use the liability method to account for income taxes. Deferred tax assets and liabilities are determined based on temporary differences between financial reporting and income tax basis of assets and liabilities, as well as net operating loss and tax credit carryforwards, and are measured using the enacted tax rates and laws that will be in effect when the differences reverse. Deferred tax assets are reduced by a valuation allowance to reflect the uncertainty associated with their ultimate realization. The effect of a change in tax rate on deferred taxes is recognized in income or loss in the period that includes the enactment date.
	We use our judgment for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. We recognize any material interest and penalties related to unrecognized tax benefits in income tax expense.
	Due to the uncertainty surrounding the realization of the net deferred tax assets in future periods, we have recorded a full valuation allowance against our otherwise recognizable net deferred tax assets as of March 31, 2014 and December 31, 2013.
Fair Value Measurements	'
	Fair Value Measurements
	We define fair value as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. We determine fair value based on the assumptions market participants use when pricing the asset or liability. We also use the fair value hierarchy that prioritizes the information used to develop these assumptions.
	We value our available-for-sale securities utilizing third party pricing services. The pricing services use many observable market inputs to determine value, including benchmark yields, reportable trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, reference data, new issue data, monthly payment information and collateral performance. We validate the prices provided by our third party pricing services by understanding the models used, obtaining market values from other pricing sources, and confirming that those securities trade in active markets. We value the balance of the release payment due to Millennium based on a discounted cash flow model.
Property and Equipment	'
	Property and Equipment
	Property and equipment are stated at cost. Depreciation is recorded using the straight-line method over the estimated useful lives of the applicable assets. Application development costs incurred for computer software developed or obtained for internal use are capitalized. Upon sale or retirement, the cost and related accumulated depreciation are eliminated from the respective account and the resulting gain or loss, if any, is included in current operations. Amortization of leasehold improvements and capital leases is recorded as depreciation expense and included in research and development and general and administrative expense. Repairs and maintenance charges that do not increase the useful life of the assets are charged to operations as incurred. Property and equipment are depreciated over the following periods:
	Laboratory equipment		5 years
	Computer equipment and software		3 to 5 years
	Leasehold improvements		Shorter of lease term or useful life of asset
	Furniture and fixtures		7 years

Significant_Accounting_Policie2

Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2014
Total Potential Gross Common Equivalent Shares	'
	Total potential gross common equivalent shares consisted of the following:
		At March 31,
		2014		2013
	Stock options		6,772,555		6,241,841
	Warrants		1,000,000		—
Property and Equipment, Depreciated Periods	'
	Property and equipment are depreciated over the following periods:
	Laboratory equipment	5 years
	Computer equipment and software	3 to 5 years
	Leasehold improvements	Shorter of lease term or useful life of asset
	Furniture and fixtures	7 years

StockBased_Compensation_Tables

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2014
Stock-Based Compensation Expense, Related to All Equity Awards	'
	Total stock-based compensation expense related to all equity awards for the three months ended March 31, 2014 and 2013 comprised the following:
		Three Months Ended			Three Months Ended
		31-Mar-14			March 31, 2013
		(in thousands)
	Effect of stock-based compensation on net loss by line item:
	Research and development	$	2,205		$	1,542
	General and administrative		1,539			2,450
Black-Scholes Valuation Model, Weighted-Average Assumptions for Stock Options	'
	For the three months ended March 31, 2014 and 2013, the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions:
		Three Months Ended			Three Months Ended
		31-Mar-14			March 31, 2013
	Risk-free interest rate		1.7	%		0.8	%
	Expected annual dividend yield		—			—
	Expected stock price volatility		71.1	%		60.4	%
	Expected term of options		5.1 years			5.0 years
Black-Scholes Valuation Model, Weighted-Average Assumptions for Employee Stock Purchase Plan	'
	For the three months ended March 31, 2014, the fair values were estimated using the Black-Scholes valuation model using the following weighted-average assumptions:
		Three Months Ended
		31-Mar-14
	Risk-free interest rate		0.2	%
	Expected annual dividend yield		—
	Expected stock price volatility		75.21	%
	Expected term of options		1.2 years

Cash_Cash_Equivalents_and_Avai1

Cash, Cash Equivalents and Available-for-Sale Securities (Tables)	3 Months Ended
	Mar. 31, 2014
Summary of Cash, Cash Equivalents and Available-for-sale Securities	'
	The following is a summary of cash, cash equivalents and available-for-sale securities:
		March 31, 2014
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	54,971	$	—	$	—		$	54,971
	Available-for-sale securities:
	Corporate obligations due in one year or less		78,107		32		(9	)		78,130
	Corporate obligations due in one to five years		10,162		18		—			10,180
	Mortgage-backed securities due after ten years		461		104		—			565
	U.S. government-sponsored enterprise obligations due in one year or less		28,240		12		(2	)		28,250
	Total available-for-sale securities		116,970		166		(11	)		117,125
	Total cash, cash equivalents and available-for-sale securities	$	171,941	$	166	$	(11	)	$	172,096
		December 31, 2013
		Cost		Gross		Gross			Estimated
				Unrealized		Unrealized			Fair Value
				Gains		Losses
		(in thousands)
	Cash and cash equivalents due in 90 days or less	$	68,114	$	—	$	—		$	68,114
	Available-for-sale securities:
	Corporate obligations due in one year or less		103,889		18		(16	)		103,891
	Corporate obligations due in one to five years		13,513		32		—			13,545
	Mortgage-backed securities due after ten years		478		104		—			582
	U.S. government-sponsored enterprise obligations due in one year or less		24,144		13		—			24,157
	U.S. government-sponsored enterprise obligations due in one to five years		4,174		5		—			4,179
	Total available-for-sale securities		146,198		172		(16	)		146,354
	Total cash, cash equivalents and available-for-sale securities	$	214,312	$	172	$	(16	)	$	214,468

Fair_Value_Tables

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2014
Assets Carried at Fair Value Measured on Recurring Basis	'
	The following table provides the assets carried at fair value measured on a recurring basis as of March 31, 2014:
		Level 1		Level 2
		(in thousands)
	Assets:
	Cash and cash equivalents	$	54,971	$	—
	Corporate obligations (including commercial paper)		—		88,310
	Mortgage-backed securities		—		565
	U.S. government-sponsored enterprise obligations		—		28,250
	Total	$	54,971	$	117,125

Accrued_Expenses_Tables

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2014
Accrued Expenses	'
	Accrued expenses consisted of the following:
		March 31,		December 31,
		2014		2013
		(in thousands)
	Accrued compensation and benefits	$	3,169	$	1,839
	Accrued clinical studies		4,114		4,009
	Accrued drug manufacturing costs		1,066		991
	Accrued preclinical studies		268		303
	Facility fee		3,000		—
	Other		2,146		2,022
	Total accrued expenses	$	13,763	$	9,164

Significant_Accounting_Policie3

Significant Accounting Policies - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014
	Segment
Significant Accounting Policies [Line Items]	'
Number of operating segments	1
Reclassifications out of accumulated other comprehensive income loss	$0
Maximum	'
Significant Accounting Policies [Line Items]	'
Maturity of highly liquid investments	'3 months

Total_Potential_Gross_Common_E

Total Potential Gross Common Equivalent Shares (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stock Options	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Common equivalent shares excluded from computation of earnings per share, amount	6,772,555	6,241,841
Warrants	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Common equivalent shares excluded from computation of earnings per share, amount	1,000,000	'

Property_and_Equipment_Depreci

Property and Equipment, Depreciation Periods (Detail)	3 Months Ended
	Mar. 31, 2014
Laboratory Equipment	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful lives	'5 years
Computer Equipment and Software | Minimum	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful lives	'3 years
Computer Equipment and Software | Maximum	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful lives	'5 years
Leasehold Improvements	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful lives	'Shorter of lease term or useful life of asset
Furniture and Fixtures	'
Property, Plant and Equipment [Line Items]	'
Property and equipment, estimated useful lives	'7 years

Stock_Based_Compensation_Expen

Stock Based Compensation Expense, Related to All Equity Awards (Detail) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Research and Development	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Effect of stock-based compensation on net loss	$2,205	$1,542
General and Administrative	'	'
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]	'	'
Effect of stock-based compensation on net loss	$1,539	$2,450

StockBased_Compensation_Additi

Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Unrecognized compensation cost, net of estimated forfeitures, related to unvested stock options and awards under ESPP	$23.60	'
Unrecognized compensation cost, weighted-average recognition period	'2 years 9 months 18 days	'
Stock options exercised	280,772	'
Stock options exercised, weighted average exercise price	$6.95	'
Modified Stock Options | Other Postretirement Benefit Plans, Defined Benefit	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Share based compensation additional exercising period for vested stock options	'6 months	'
Additional Stock Based Compensation Expense	$0.40	'
Employee Stock Purchase Plan	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Stock options granted, weighted average fair value	$6.33	'
Stock Options	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Stock options granted	1,152,884	986,094
Stock options granted, weighted average fair value	$7.79	$20.44
Stock options granted, weighted average exercise price	$13.13	$37.33

BlackScholes_Valuation_Model_W

Black-Scholes Valuation Model, Weighted-Average Assumptions (Detail)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stock Options	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Risk-free interest rate	1.70%	0.80%
Expected annual dividend yield	'	'
Expected stock price volatility	71.10%	60.40%
Expected term of options	'5 years 1 month 6 days	'5 years
Employee Stock Purchase Plan	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'
Risk-free interest rate	0.20%	'
Expected annual dividend yield	'	'
Expected stock price volatility	75.21%	'
Expected term of options	'1 year 2 months 12 days	'

Summary_of_Cash_Cash_Equivalen

Summary of Cash, Cash Equivalents and Available-for-sale Securities (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Cash and cash equivalents due in 90 days or less, Cost	$54,971	$68,114	'	'
Cash and cash equivalents due in 90 days or less, Gross Unrealized Gains	'	'	'	'
Cash and cash equivalents due in 90 days or less, Gross Unrealized Losses	'	'	'	'
Cash and cash equivalents due in 90 days or less, Estimated Fair Value	54,971	68,114	101,142	175,742
Total available-for-sale securities, Cost	116,970	146,198	'	'
Total available-for-sale securities, Gross Unrealized Gains	166	172	'	'
Total available-for-sale securities, Gross Unrealized Losses	-11	-16	'	'
Total available-for-sale securities, Estimated Fair Value	117,125	146,354	'	'
Total cash, cash equivalents and available-for-sale securities, Cost	171,941	214,312	'	'
Total cash, cash equivalents and available-for-sale securities, Gross Unrealized Gains	166	172	'	'
Total cash, cash equivalents and available-for-sale securities, Gross Unrealized Losses	-11	-16	'	'
Total cash, cash equivalents and available-for-sale securities	172,096	214,468	'	'
Corporate Obligations	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available-for-sale securities, due in one year or less, Cost	78,107	103,889	'	'
Available-for-sale securities, due in one year or less, Gross Unrealized Gains	32	18	'	'
Available-for-sale securities, due in one year or less, Gross Unrealized Losses	-9	-16	'	'
Available-for-sale securities, due in one year or less, Estimated Fair Value	78,130	103,891	'	'
Available-for-sale securities, due in one to five years, Cost	10,162	13,513	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Gains	18	32	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Losses	'	'	'	'
Available-for-sale securities, due in one to five years, Estimated Fair Value	10,180	13,545	'	'
Mortgage-Backed Securities	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available-for-sale securities due after ten years, Cost	461	478	'	'
Available-for-sale securities due after ten years, Gross Unrealized Gains	104	104	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Losses	'	'	'	'
Available-for-sale securities due after ten years, Estimated Fair Value	565	582	'	'
U.S. Government Sponsored Enterprise Obligations	'	'	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'
Available-for-sale securities, due in one year or less, Cost	28,240	24,144	'	'
Available-for-sale securities, due in one year or less, Gross Unrealized Gains	12	13	'	'
Available-for-sale securities, due in one year or less, Gross Unrealized Losses	-2	'	'	'
Available-for-sale securities, due in one year or less, Estimated Fair Value	28,250	24,157	'	'
Available-for-sale securities, due in one to five years, Cost	28,240	4,174	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Gains	12	5	'	'
Available-for-sale securities, due in one to five years, Gross Unrealized Losses	-2	'	'	'
Available-for-sale securities, due in one to five years, Estimated Fair Value	$28,250	$4,179	'	'

Cash_Cash_Equivalents_and_Avai2

Cash, Cash Equivalents and Available-for-Sale Securities - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Schedule of Available-for-sale Securities [Line Items]	'	'
Available-for-sale securities realized gains or losses	$0	$0
Other-than-temporary impairments on Available-for-sale securities	0	0
Less Than Twelve Months	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of debt securities held in an unrealized loss position	17	'
Available for sale securities debt fair value	43,600,000	'
Foreign Financial Institution and Other Corporate Debt Securities	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Available for sale securities number of financial institution debt securities and other corporate debt securities located in foreign countries	13	'
Available for sale securities debt fair value	41,000,000	'
Number of securities unrealized losses	7	'
Available for sale securities debt gross unrealized losses	3,000	'
Available for sale securities debt fair value, short term	$14,300,000	'
12 months or greater	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Number of debt securities held in an unrealized loss position	0	'

Assets_Carried_at_Fair_Value_M

Assets Carried at Fair Value Measured on Recurring Basis (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Total cash, cash equivalents and available-for-sale securities	$172,096	$214,468
Level 1	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and cash equivalents	54,971	'
Corporate obligations (including commercial paper)	'	'
Mortgage-backed securities	'	'
U.S. government-sponsored enterprise obligations	'	'
Total cash, cash equivalents and available-for-sale securities	54,971	'
Level 2	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]	'	'
Cash and cash equivalents	'	'
Corporate obligations (including commercial paper)	88,310	'
Mortgage-backed securities	565	'
U.S. government-sponsored enterprise obligations	28,250	'
Total cash, cash equivalents and available-for-sale securities	$117,125	'

Fair_Value_Additional_Informat

Fair Value - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available-for-sale securities	$117,125,000	$146,354,000
Transfers of assets or liabilities between Level 1 and Level 2	0	'
Payment at Fair value	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Due to Millennium, Fair value	6,600,000	'
Fair Value, Inputs, Level 3	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Available-for-sale securities	$0	$0
Maximum	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Maturity of highly liquid investments	'3 months	'

Collaborations_Additional_Info

Collaborations - Additional Information (Detail) (USD $)

1 Months Ended

3 Months Ended

1 Months Ended

3 Months Ended

12 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

3 Months Ended

Jul. 17, 2012

Jul. 31, 2010

Mar. 31, 2014

Mar. 31, 2013

Feb. 24, 2014

Nov. 30, 2008

Apr. 30, 2013

Mar. 31, 2014

Dec. 31, 2012

Jul. 17, 2012

Jul. 17, 2012

Mar. 31, 2014

Mar. 31, 2014

Mar. 31, 2014

Feb. 28, 2014

Jul. 17, 2012

Mar. 31, 2014

Entity

Product

BRP

Amended Agreement

Amended Agreement

Line of Credit

Cash

Collaboration

Maximum

Minimum

Minimum

Mundipharma and Purdue

Mundipharma and Purdue

Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Up-front license fee

'

$13,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Release payment

'

'

'

'

'

'

'

'

15,000,000

'

'

'

'

'

'

'

'

Release payment, fair value

'

'

'

'

'

'

'

'

14,400,000

'

'

'

'

'

'

'

'

Amount paid on release payment during the period

'

'

'

'

'

'

'

6,700,000

1,700,000

'

'

'

'

'

'

'

'

Development cost of distinct product candidates

'

'

'

'

'

'

'

'

'

'

'

'

5,000,000

'

10,000,000

'

'

Number of distinct product candidates

'

'

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Approval and commercialization cost of distinct products payable

'

'

'

'

'

'

'

'

'

'

'

'

450,000,000

'

'

'

'

Percent of royalty on net sale

'

'

'

'

'

'

'

'

'

'

'

'

11.00%

7.00%

'

'

'

Research and development expense

'

'

34,491,000

20,231,000

'

'

'

'

'

'

'

10,000,000

'

'

'

'

'

Prior written notice for termination on the breach of agreement by the other party

'

'

'75 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Prior written notice for termination on nonpayment by the other party

'

'

'30 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Prior written notice for termination after the end of the research term

'

'

'180 days

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Strategic Alliance Agreement Termination date

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'July 17, 2012

Royalty rate on future sales

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.00%

'

Recovery of research and development funding

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

260,000,000

'

Royalty rate payable after initial research and development cost recovery

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1.00%

'

Royalty payable description

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'After this cost recovery, our royalty obligations to Mundipharma and Purdue will be reduced to a one percent royalty on net sales in the United States of products that were previously subject to the strategic alliance.

Royalty term and royalty rate reduction

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Royalty payment, maximum reduction

50.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line Of credit facility maximum borrowing capacity

'

'

'

'

100,000,000

50,000,000

'

'

'

'

'

'

'

'

'

'

'

Stock to be issued under securities purchase agreement

5,416,565

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Aggregate consideration to be received on stock transaction

78,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt amount plus accrued interest

'

'

'

'

'

'

'

'

'

51,000,000

'

'

'

'

'

'

'

Sale of stock consideration to be received on transaction

'

'

'

'

'

'

'

'

'

'

$27,500,000

'

'

'

'

'

'

Stock to be issued under securities purchase agreement, price per share

$14.50

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of entities

2

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Number of shares of common stock sold

'

'

'

'

'

'

11,416,565

'

'

'

'

'

'

'

'

'

'

Number of shares of common stock sold, per share

'

'

'

'

'

'

$40

'

'

'

'

'

'

'

'

'

'

Debt_Facility_Agreement_Additi

Debt Facility Agreement - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended
	Feb. 24, 2014	Mar. 31, 2014	Dec. 31, 2013	Nov. 30, 2008
Debt Instrument [Line Items]	'	'	'	'
Line Of credit facility maximum borrowing capacity	$100,000,000	'	'	$50,000,000
Minimum draw down during the 12 months following effective date	25,000,000	'	'	'
Common stock warrants issued	1,000,000	'	'	'
Common stock warrants issued, exercise price	$13.83	'	'	'
Debt instrument, interest rate	7.95%	'	'	'
Debt instrument, final payment date	'	15-Dec-19	'	'
Percentage of fee to be paid on undrawn portion	'	3.00%	'	'
Commitment fee amount	'	3,000,000	'	'
Total cash, cash equivalents and available-for-sale securities, Cost	'	171,941,000	214,312,000	'
Total cost of securing loan commitment	'	11,800,000	'	'
Fair value of the warrants issued	'	8,400,000	'	'
Transaction cost	'	400,000	'	'
Interest expense	'	1,100,000	'	'
Volatility rate	'	59.01%	'	'
Risk free interest rate	'	2.20%	'	'
Contractual life	'	'7 years	'	'
Expected dividend yield	'	0.00%	'	'
Additional warrants to purchase common stock, percentage	'	50.00%	'	'
Consecutive trading day period	'	'20 days	'	'
Minimum	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Total cash, cash equivalents and available-for-sale securities, Cost	'	$25,000,000	'	'
Maximum	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Number of shares issuable under the agreement	'	9,500,000	'	'
Deerfield	'	'	'	'
Debt Instrument [Line Items]	'	'	'	'
Principal amount of loan, percentage	'	100.00%	'	'
Ownership percentage	'	9.99%	'	'

Accrued_Expenses_Detail

Accrued Expenses (Detail) (USD $)	Mar. 31, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Accrued Expenses [Line Items]	'	'
Accrued compensation and benefits	$3,169	$1,839
Accrued clinical studies	4,114	4,009
Accrued drug manufacturing costs	1,066	991
Accrued preclinical studies	268	303
Facility fee	3,000	'
Other	2,146	2,022
Total accrued expenses	$13,763	$9,164