Agios Pharmaceuticals (AGIO) 10-Q 7 Aug 14 2014 Q2 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	6 Months Ended
	Jun. 30, 2014	Aug. 06, 2014
Document And Entity Information [Abstract]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Jun-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q2	'
Trading Symbol	'AGIO	'
Entity Registrant Name	'AGIOS PHARMACEUTICALS INC	'
Entity Central Index Key	'0001439222	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Non-accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	34,458,016

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$108,247	$71,560
Marketable securities	130,233	95,209
Unbilled collaboration receivable - related party	'	476
Prepaid expenses and other current assets	2,842	2,502
Refundable income taxes	3,841	'
Total current assets	245,163	169,747
Marketable securities	22,631	27,125
Property and equipment, net	3,210	3,758
Restricted cash	571	571
Other assets	455	4
Total assets	272,030	201,205
Current liabilities:	'	'
Accounts payable	5,388	3,678
Accrued expenses	5,456	6,586
Income taxes payable	'	1,462
Deferred revenue- related party	33,644	25,072
Deferred rent	142	123
Other current liabilities	8	9
Total current liabilities	44,638	36,930
Deferred revenue, net of current portion - related party	26,697	32,567
Deferred rent, net of current portion	145	220
Other non-current liabilities	2	6
Commitments and contingencies	'	'
Stockholders' equity:	'	'
Preferred stock, $0.001 par value; 25,000,000 shares authorized; no shares issued and outstanding	'	'
Common stock, $0.001 par value; 125,000,000 shares authorized; 34,424,415 and 31,202,542 shares issued and outstanding at June 30, 2014 and December 31, 2013, respectively	34	31
Additional paid-in capital	344,490	244,881
Accumulated other comprehensive income	12	14
Accumulated deficit	-143,988	-113,444
Total stockholders' equity	200,548	131,482
Total liabilities and stockholders' equity	$272,030	$201,205

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]	'	'
Preferred stock, par value	$0.00	$0.00
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$0.00	$0.00
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	34,424,415	31,202,542
Common stock, shares outstanding	34,424,415	31,202,542

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations (USD $)	3 Months Ended		6 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]	'	'	'	'
Collaboration revenue - related party	$8,411	$6,268	$16,822	$12,536
Operating expenses:	'	'	'	'
Research and development	22,576	12,958	39,982	24,420
General and administrative	4,165	1,836	7,454	3,688
Total operating expenses	26,741	14,794	47,436	28,108
Loss from operations	-18,330	-8,526	-30,614	-15,572
Interest income	34	5	70	13
Loss before provision for income taxes	-18,296	-8,521	-30,544	-15,559
Provision for income taxes	'	-99	'	-289
Net loss	-18,296	-8,620	-30,544	-15,848
Cumulative preferred stock dividends	'	-1,798	'	-3,595
Net loss applicable to common stockholders	($18,296)	($10,418)	($30,544)	($19,443)
Net loss per share applicable to common stockholders - basic and diluted	($0.54)	($2.80)	($0.94)	($5.27)
Weighted-average number of common shares used in net loss per share applicable to common stockholders - basic and diluted	33,602,472	3,722,963	32,506,739	3,690,669

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Comprehensive Loss (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Statement Of Income And Comprehensive Income [Abstract]	'	'	'	'
Net loss	($18,296)	($8,620)	($30,544)	($15,848)
Other comprehensive loss:	'	'	'	'
Unrealized loss on available-for-sale securities	-21	-3	-2	-2
Comprehensive loss	($18,317)	($8,623)	($30,546)	($15,850)

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Cash Flows (USD $)	6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013
Operating activities	'	'
Net loss	($30,544)	($15,848)
Adjustments to reconcile net loss to net cash used in operating activities:	'	'
Depreciation	659	723
Stock-based compensation expense	3,886	753
Net amortization (accretion) of premium (discount) on investments	305	-9
Changes in operating assets and liabilities:	'	'
Unbilled collaboration receivable - related party	476	'
Prepaid expenses and other assets	-791	-2,690
Accounts payable	1,684	-271
Accrued expenses and other liabilities	-1,130	1,845
Deferred rent	-55	-36
Refundable income taxes and income taxes payable	-5,303	266
Deferred revenue - related party	2,702	-12,536
Net cash used in operating activities	-28,111	-27,803
Investing activities	'	'
Purchases of marketable securities	-126,338	-23,195
Proceeds from maturities and sales of marketable securities	95,501	38,086
Purchases of property and equipment	-99	-976
Net cash (used in) provided by investing activities	-30,936	13,915
Financing activities	'	'
Proceeds from public offering of common stock, net of commissions and offering costs	94,698	'
Net proceeds from stock option exercises and issuance of common stock	1,036	72
Net cash provided by financing activities	95,734	72
Net increase (decrease) in cash and cash equivalents	36,687	-13,816
Cash and cash equivalents at beginning of the period	71,560	91,297
Cash and cash equivalents at end of the period	108,247	77,481
Supplemental disclosure of non-cash investing and financing transactions	'	'
Additions to property, plant and equipment included in accounts payable	12	'
Vesting of restricted stock	-6	'
Public offering costs included in accounts payable	13	'
Supplemental cash flow information	'	'
Cash paid for income taxes	$5,958	'

Overview_and_Basis_of_Presenta

Overview and Basis of Presentation	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Overview and Basis of Presentation	'
	1. Overview and Basis of Presentation
	Agios Pharmaceuticals, Inc. (“Agios” or “the Company”) is a biopharmaceutical company committed to the fundamental transformation of patients’ lives through scientific leadership in the field of cancer metabolism and inborn errors of metabolism. The Company has built a unique set of core capabilities in the field of cellular metabolism, with the goal of making transformative, first or best in class medicines. The Company’s therapeutic areas of focus are cancer and inborn errors of metabolism, which are a broad group of more than 600 rare genetic diseases caused by mutations, or defects, of single metabolic genes. In both of these areas, the Company is seeking to unlock the biology of cellular metabolism to create transformative therapies. The Company is located in Cambridge, Massachusetts.
	The condensed consolidated interim balance sheet as of June 30, 2014, the condensed consolidated interim statements of operations and comprehensive loss for the three and six months ended June 30, 2014 and 2013 and the statements of cash flows for the six months ended June 30, 2014 and 2013, are unaudited. The unaudited condensed consolidated interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s condensed consolidated financial position as of June 30, 2014, and its results of operations for the three and six months ended June 30, 2014 and 2013 and cash flows for the six months ended June 30, 2014 and 2013. The financial data and the other financial information disclosed in these notes to the condensed consolidated interim financial statements related to the three and six month periods are also unaudited. The results of operations for the three and six months ended June 30, 2014 are not necessarily indicative of the results to be expected for the year ending December 31, 2014 or for any other future annual or interim period. The condensed consolidated interim financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2013 that was filed with the Securities and Exchange Commission (the “SEC”) on March 18, 2014.
	The Company’s condensed consolidated financial statements include the Company’s accounts and the accounts of the Company’s wholly-owned subsidiary, Agios Securities Corporation. All intercompany transactions have been eliminated in consolidation. The condensed consolidated interim financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”).
	On July 29, 2013, the Company closed an initial public offering (“IPO”) of its common stock, which resulted in the sale of 6,772,221 shares of its common stock at a public offering price of $18.00 per share, before underwriting commissions and discounts, including 883,333 shares of common stock issued upon the exercise in full by the underwriters of their option to purchase additional shares at the public offering price to cover over-allotments. The Company received net proceeds from the IPO of $111.0 million, after deducting underwriting discounts, commissions, and expenses payable by the Company. Additionally, an affiliate of Celgene Corporation (“Celgene”), the Company’s cancer metabolism strategic alliance partner, purchased 708,333 shares of common stock in a separate private placement concurrent with the completion of the IPO at a purchase price of $18.00 per share for aggregate proceeds of $12.8 million.
	In connection with preparing for the IPO, the Company’s Board of Directors and stockholders approved a 1-for-2.75 reverse stock split of the Company’s common stock. The reverse stock split became effective on July 11, 2013. All share and per share amounts in the condensed consolidated interim financial statements and notes thereto have been retroactively adjusted for all periods presented to give effect to this reverse stock split, including reclassifying an amount equal to the reduction in par value of common stock to additional paid-in capital. In connection with the closing of the IPO, all of the Company’s outstanding convertible preferred stock automatically converted to common stock as of July 29, 2013, resulting in an additional 19,731,564 shares of common stock of the Company becoming outstanding. The significant increase in common stock outstanding in July 2013 impacts the period-over-period comparability of the Company’s net loss per share calculations.
	In April 2014, the Company completed a public offering of 2,000,000 shares of its common stock at a public offering price of $44.00 per share, before underwriting commissions and discounts. The Company received net proceeds from this offering of $82.3 million, after deducting underwriting discounts, commissions and expenses payable by the Company. Celgene purchased 294,800 shares of the Company’s common stock in the offering. In addition, the Company granted the underwriters the right to purchase up to an additional 300,000 shares of its common stock which was exercised in May 2014 resulting in additional net proceeds to the Company of $12.4 million, after underwriting discounts and commissions paid by the Company.

Summary_of_Significant_Account

Summary of Significant Accounting Policies and Recent Accounting Pronouncements	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
Summary of Significant Accounting Policies and Recent Accounting Pronouncements	'
	2. Summary of Significant Accounting Policies and Recent Accounting Pronouncements
	There have been no material changes to the significant accounting policies previously disclosed in the Annual Report on Form 10-K for the year ended December 31, 2013.
	In June 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-12, Compensation—Stock Compensation (Topic 718). The ASU clarifies how entities should treat performance targets that can be achieved after the requisite service period of a share-based payment award. The accounting standard is effective for interim and annual periods beginning after December 15, 2015. The Company is currently in the process of evaluating the impact of the guidance on its financial position, results of operation, and cash flows.
	In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). The ASU provides for a single comprehensive model for use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. The accounting standard is effective for interim and annual periods beginning after December 15, 2016 with no early adoption permitted. The Company is currently in the process of evaluating the impact of the guidance on its financial position, results of operation, and cash flows.
	Accounting standards that have been issued by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.

Fair_Value_Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2014
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	3. Fair Value Measurements
	The Company records cash equivalents and marketable securities at fair value. Accounting Standards Codification (“ASC”) Topic 820, Fair Value Measurements and Disclosures, established a fair value hierarchy for those instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). The hierarchy consists of three levels:
	Level 1 – Unadjusted quoted prices in active markets for identical assets or liabilities.
	Level 2 – Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability.
	Level 3 – Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability in which there is little, if any, market activity for the asset or liability at the measurement date.
	The following table summarizes the cash equivalents and marketable securities measured at fair value on a recurring basis as of June 30, 2014 (in thousands):
		Level 1		Level 2		Level 3		Total
	Cash equivalents	$	105,084	$	480	$	—	$	105,564
	Marketable securities:
	Certificates of deposit		—		12,835		—		12,835
	U.S. Treasuries		140,029		—		—		140,029
		$	245,113	$	13,315	$	—	$	258,428
	The following table summarizes the cash equivalents and marketable securities measured at fair value on a recurring basis as of December 31, 2013 (in thousands):
		Level 1		Level 2		Level 3		Total
	Cash equivalents	$	68,792	$	—	$	—	$	68,792
	Marketable securities:
	Certificates of deposit		—		6,915		—		6,915
	U.S. Treasuries		115,419		—		—		115,419
		$	184,211	$	6,915	$	—	$	191,126
	Cash equivalents and marketable securities have been initially valued at the transaction price and subsequently valued, at the end of each reporting period, utilizing third party pricing services or other market observable data. The pricing services utilize industry standard valuation models, including both income and market based approaches and observable market inputs to determine value. The Company validates the prices provided by its third party pricing services by reviewing their pricing methods and obtaining market values from other pricing sources. After completing its validation procedures, the Company did not adjust or override any fair value measurements provided by the pricing services as of June 30, 2014 or December 31, 2013.
	There have been no changes to the valuation methods during the three or six months ended June 30, 2014 and 2013. The Company evaluates 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 and six months ended June 30, 2014 or the year ended December 31, 2013. The Company had no financial assets or liabilities that were classified as Level 3 at any point during the three and six months ended June 30, 2014 or the year ended December 31, 2013.

Marketable_Securities

Marketable Securities	6 Months Ended
	Jun. 30, 2014
Investments Debt And Equity Securities [Abstract]	'
Marketable Securities	'
	4. Marketable Securities
	Marketable securities at June 30, 2014 and December 31, 2013 consisted primarily of investments in United States Treasuries and certificates of deposit. Management determines the appropriate classification of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its marketable securities as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities. Marketable securities are recorded at fair value, with unrealized gains and losses included as a component of accumulated other comprehensive loss in stockholders’ equity and a component of total comprehensive loss in the condensed consolidated interim statements of comprehensive loss, until realized. Realized gains and losses are included in investment income on a specific-identification basis. There were no realized gains or losses on marketable securities for the three or six months ended June 30, 2014 and 2013.
	The Company reviews marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the condensed consolidated interim statements of operations if the Company has experienced a credit loss, has the intent to sell the marketable security, or if it is more likely than not that the Company will be required to sell the marketable security before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period.
	Marketable securities at June 30, 2014 consist of the following (in thousands):
		Amortized Cost		Unrealized		Unrealized			Fair
				Gains		Losses			Value
	Current:
	Certificates of deposit	$	12,850	$	—	$	(15	)	$	12,835
	U.S. Treasuries		117,368		34		(4	)		117,398
	Non-current:
	U.S. Treasuries		22,634		2		(5	)		22,631
		$	152,852	$	36	$	(24	)	$	152,864
	Marketable securities at December 31, 2013 consist of the following (in thousands):
		Amortized Cost		Unrealized		Unrealized			Fair
				Gains		Losses			Value
	Current:
	Certificates of deposit	$	6,920	$	—	$	(5	)	$	6,915
	U.S. Treasuries		88,287		8		(1	)		88,294
	Non-current:
	U.S. Treasuries		27,113		12		—			27,125
		$	122,320	$	20	$	(6	)	$	122,334
	At June 30, 2014 and December 31, 2013, the Company held both current and non-current investments. Investments classified as current have maturities of less than one year. Investments classified as non-current are those that (i) have maturities of one to two years and (ii) management does not intend to liquidate within the next twelve months, although these funds are available for use and therefore classified as available-for-sale.
	At June 30, 2014 and December 31, 2013, the Company held 66 and 33 debt securities that were in an unrealized loss position for less than one year, respectively. The aggregate fair value of debt securities in an unrealized loss position at June 30, 2014 and December 31, 2013 was $57.4 million and $31.7 million, respectively. There were no individual securities that were in a significant unrealized loss position as of June 30, 2014 and December 31, 2013. The Company evaluated its securities for other-than-temporary impairment and considered the decline in market value for the securities to be primarily attributable to current economic and market conditions. It is not more likely than not that the Company will be required to sell the securities, and the Company does not intend to do so prior to the recovery of the amortized cost basis. Based on this analysis, these marketable securities were not considered to be other-than-temporarily impaired as of June 30, 2014 and December 31, 2013.

Collaboration_Agreements

Collaboration Agreements	6 Months Ended
	Jun. 30, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]	'
Collaboration Agreements	'
	5. Collaboration Agreements
	Celgene
	In April 2010, the Company entered into a collaboration agreement focused on cancer metabolism with Celgene Corporation, or Celgene, a related party through ownership of the Company’s common stock. This agreement was amended in October 2011 as described below. The goal of the collaboration is to discover, develop and commercialize disease-altering therapies in oncology based on the Company’s cancer metabolism research platform. The Company is leading discovery, preclinical and early clinical development for all cancer metabolism programs under the collaboration. The discovery phase of the amended collaboration was to expire in April 2014, subject to Celgene’s option to extend the discovery phase for up to an additional two years with additional funding to the Company. In December 2013, Celgene elected to extend the term of the initial discovery period from four to five years, to April 2015. Celgene has the option to obtain exclusive rights for the further development and commercialization of certain of the programs, and the Company will retain rights to the others. The Company may elect to participate in a portion of sales activities for the medicines from such programs in the United States. In addition, for certain of the programs that Celgene chooses to license, the Company may elect to retain full rights to develop and commercialize medicines from these programs in the United States.
	Pursuant to the collaboration, the Company is responsible for nominating development candidates, of which two must be confirmed by the Joint Research Committee (“JRC”) during the discovery phase. During the year ended December 31, 2012, the Company nominated its first development candidate, and during the year ended December 31, 2013, the Company nominated its second development candidate, both of which have been confirmed by the JRC, pursuant to the agreement. The JRC will be dissolved and its activities and authority terminated upon the end of the discovery phase. For each development candidate, Celgene may elect to progress such development candidate into preclinical development. If Celgene makes such an election, the Company will be required to conduct studies to meet the requirements for filing an Investigational New Drug application, or IND, or IND-enabling studies, and, following the successful completion as confirmed by the JRC, the Company will file an IND to commence clinical studies of such development candidate. If the FDA accepts the IND, Celgene may request that the Company conduct an initial phase 1 study, for which the Company would be entitled to receive a milestone payment of $5.0 million upon enrollment of the last patient in the phase 1 study, provided, however, that, if the Joint Development Committee (“JDC”) by mutual consent adopts a development plan and related development budget pursuant to which the Company undertakes significant additional development activities under such program following IND acceptance in parallel with a Celgene requested Phase I multiple ascending dose study, then the JDC by mutual consent will determine the amount of an increase to such amount necessary to cover such excess costs and expenses pursuant to such development plan. Celgene will not be responsible for such program expenses if the program becomes a split licensed program, as described below.
	Celgene may elect to convert each discovery program for which the Company has nominated a development candidate into a co-commercialized licensed program, the attributes of which are described below. The Company has the right, exercisable during a specified period following FDA acceptance of the applicable IND, to convert one of every three co-commercialized licensed programs into a split licensed program, for which the Company will retain the United States rights, other attributes of which are further described below. The Company’s isocitrate dehydrogenase 2 (“IDH2”) program is not a split licensed program. In June 2014, Celgene exercised its option to an exclusive global license for the development and commercialization of AG-221. The Company elected its IDH1 program to be its first split licensed program and in January 2014, elected to exercise its option to retain development and commercialization rights to AG-120 in the United States.
	The Company will retain the rights to the development candidate and certain other compounds for which Celgene does not elect to progress into preclinical development or convert into a co-commercialized licensed program. In addition, if the JRC or Celgene elects not to continue collaboration activities with respect to a particular target, either the Company or Celgene would have the right to independently undertake a discovery program on such target and would have rights to specified compounds from such program, subject to certain “buy-in” rights granted to the other party.
	The agreement provides for three types of licensed programs as discussed above:
	Co-Commercialized Licensed Programs: Celgene will lead and, following either IND acceptance by the FDA or, if Celgene requests the Company to conduct the initial phase 1 study upon completion of such phase 1 study, will fund global development and commercialization. The Company has the right to participate in a portion of sales activities in the United States for products from co-commercialized programs in accordance with the applicable commercialization plan. The Company will be eligible to receive milestone payments and royalties arising from the licensed program.
	Split Licensed Programs: Celgene will lead development and commercialization outside the United States and the Company will lead development and commercialization in the United States. The Company and Celgene will equally fund the global development costs of each split licensed program that are not specific to any particular region or country, Celgene will be responsible for development and commercialization costs specific to countries outside the United States, and the Company will be responsible for development and commercialization costs specific to the United States. The Company will retain profits generated in the United States and will also be eligible to receive milestone payments and royalties arising from net sales outside the United States. The Company will be obligated to pay Celgene royalties arising from net sales in the United States.
	Buy-In Programs: If a party elects to independently undertake a discovery program, with respect to a particular target under the agreement, the party that is conducting the independent program that becomes a buy-in program will lead the development and commercialization of such program. The party that elects to buy in to such program will be responsible for funding a portion of development costs incurred after acceptance of an IND for a buy-in program compound, and the lead party will be responsible for all other development costs and all commercialization costs for products from such buy-in program. The commercializing party will be obligated to pay the buy-in party specified royalties on worldwide net sales.
	In addition, Celgene may license certain discovery programs for which the Company does not nominate or the JRC does not confirm as a development candidate and for which Celgene will lead and fund global development and commercialization.
	The term of the agreement will continue, unless earlier terminated by either party, until the expiration of the last-to-expire of all royalty terms with respect to all royalty-bearing products or the expiration of the option term if Celgene fails to extend the term of the agreement, does not select any compounds pursuant to the agreement, and there are no existing programs covered by the agreement.
	Celgene may terminate the agreement for convenience in its entirety or with respect to one or more programs upon thirty days written notice to the Company. Either the Company or Celgene may terminate the agreement in its entirety or with respect to one or more programs, if the other party is in material breach and fails to cure such breach within the specified cure period; however, if such breach relates solely to a specific program, the non-breaching party may only terminate the agreement with respect to such program. Either the Company or Celgene may terminate the agreement in the event of specified insolvency events involving the other party.
	Under the terms of the agreement, the Company received an upfront payment of approximately $121.2 million. In addition, Celgene purchased 5,190,551 shares of Series B convertible preferred stock (Series B Preferred Stock) at a price of $1.70 per share, resulting in net proceeds to the Company of approximately $8.8 million. The Company determined the price paid by Celgene for the Series B Preferred Stock represented a premium over the fair value of the Company’s Series B Preferred Stock as determined by the implied value of the Series B Preferred Stock pursuant to a contemporaneous valuation analysis that allocated the equity value of the Company to the various classes of its then-outstanding securities. The Company accounted for the $3.1 million premium as additional consideration under the agreement and the Series B Preferred Stock was recorded at its fair value of $5.7 million. In connection with the 1-for-2.75 reverse stock split of the Company’s common stock, the shares of Series B Preferred Stock converted into 1,887,473 shares of common stock upon the closing of the Initial Public Offering in July 2013.
	The Company identified several deliverables under the agreement, including the option to obtain a license or licenses and research and development services to be performed by the Company on behalf of Celgene, including manufacturing of clinical and preclinical supply through completion of phase 1 clinical trials. The Company concluded that the option to obtain a license does not have stand-alone value to Celgene apart from the related research and development services deliverables as there are no other vendors selling similar, competing products on a stand-alone basis, Celgene does not have the contractual right to resell the option to obtain a license, and Celgene is unable to use the license for its intended purpose without the Company’s performance of research and development services. In addition, the Company was not able to estimate the fair value of the undelivered items in the agreement. Accordingly, the Company has accounted for the deliverables as one unit of accounting. As such, a total of $124.3 million of consideration is being recognized as revenue on a straight-line basis over the period over which the Company expects to fulfill its performance obligations (the performance period), which was determined to be 6 years. The Company evaluates the performance period at each reporting period.
	In October 2011, the agreement was amended to extend the term of the initial discovery period from three to four years, to April 2014. The amendment was not deemed to be a material modification to the arrangement since there were no changes in the deliverables or the total arrangement consideration, as the provisions of the original agreement provided Celgene with the option to extend the research period for the same consideration. Celgene made a payment to the Company of $20.0 million pursuant to the amendment. The payment was combined with the unamortized upfront payment and premium and is being recognized as revenue on a straight-line basis over the performance period.
	In December 2013, Celgene elected to extend the term of the initial discovery period from four to five years, to April 2015. As a result of the extension, the Company received a $20.0 million extension payment from Celgene in May 2014. The amount was combined with the unamortized upfront payment and premium and is being recognized as revenue on a straight-line basis over the performance period. During the three and six months ended June 30, 2014 and for the year ended December 31, 2013, the Company recognized revenue of $2.1 million, $4.3 million and $0.5 million, respectively, related to this extension. The Company may also be eligible to receive an additional $20.0 million extension payment in the event Celgene elects to extend the discovery phase until April 2016.
	The Company recorded revenue of approximately $8.4 million and $6.3 million in connection with the Celgene collaboration during the three months ended June 30, 2014 and 2013, respectively, and approximately $16.8 million and $12.5 million during the six months ended June 30, 2014 and 2013, respectively.
	The Company is eligible to receive up to $120.0 million in potential milestone payments payable for each program selected by Celgene. The potential milestone payments for each such program are comprised of: (i) a $25.0 million milestone payment upon achievement of a specified clinical development milestone event, (ii) up to $70.0 million in milestone payments upon achievement of specified regulatory milestone events, and (iii) a $25.0 million milestone payment upon achievement of a specified commercial milestone event. The Company is also eligible to receive additional milestone payments specific to co-commercialized licensed programs and split licensed programs. Each co-commercialized licensed program is eligible to receive a minimum one-time milestone payment of $5.0 million upon the enrollment of the last patient in a phase 1 multiple ascending dose study. In addition, the Company is eligible to receive a substantive milestone payment of $22.5 million upon achievement of an early clinical development milestone event for certain co-commercialized licensed programs. In connection with the first split licensed program under the collaboration, the Company’s IDH1 Program, AG-120, the Company is eligible to receive a one-time payment of $25.0 million upon the dosing of the last patient in a Company-sponsored phase 2 clinical trial. The Company may also receive royalties at tiered, low- to mid-teen percentage rates on net sales and has the option to participate in the development and commercialization of certain products in the United States. As of June 30, 2014, the Company has not received any milestone or royalty payments under the agreement.
	The Company has concluded that certain of the clinical development and regulatory milestones that may be received under the Celgene Agreement, if the Company is involved in future product development and commercialization, are substantive. Factors considered in the evaluation of the milestones included the degree of risk associated with performance of the milestone, the level of effort and investment required, whether the milestone consideration was reasonable relative to the deliverables and whether the milestone was earned at least in part based on the Company’s performance. Revenues from substantive milestones, if they are nonrefundable, are recognized as revenue upon successful accomplishment of the milestones. Clinical and regulatory milestones are deemed non-substantive if they are based solely on the collaborator’s performance. Non-substantive milestones will be recognized when achieved to the extent the Company has no remaining performance obligations under the arrangement. Milestone payments earned upon achievement of commercial milestone events will be recognized when earned.

Accrued_Expenses_and_Other_Cur

Accrued Expenses and Other Current Liabilities	6 Months Ended
	Jun. 30, 2014
Payables And Accruals [Abstract]	'
Accrued Expenses and Other Current Liabilities	'
	6. Accrued Expenses and Other Current Liabilities
	Accrued expenses and other current liabilities consist of the following (in thousands):
		June 30,		December 31,
		2014		2013
	Accrued compensation	$	2,371	$	3,642
	Accrued contracted research and development costs		2,372		2,484
	Accrued professional fees		620		320
	Accrued other		93		140
	Total	$	5,456	$	6,586

ShareBased_Payments

Share-Based Payments	6 Months Ended
	Jun. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Share-Based Payments	'
	7. Share-Based Payments
	2013 Stock Incentive Plan
	In June 2013, the Company’s Board of Directors adopted, and in July 2013, the Company’s stockholders approved, the 2013 Stock Incentive Plan (the “2013 Plan”). The 2013 Plan became effective upon the closing of the IPO and provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. As of June 30, 2014, the total number of shares reserved under all equity plans is 4,831,387 and the Company had 847,826 shares available for future issuance under such plans. The 2013 Plan provides for an annual increase, to be added on the first day of each fiscal year, beginning with the fiscal year ending December 31, 2014 and continuing until the expiration of the 2013 Plan, equal to the lesser of (i) 2,000,000 shares of Common Stock, (ii) 4% of the outstanding shares of Common Stock on such date or (iii) an amount determined by the Company’s Board of Directors. On January 1, 2014, the annual increase for the 2013 Plan resulted in an additional 1,242,966 shares authorized for issuance.
	The following table summarizes the activity of all stock incentive plans for the six months ended June 30, 2014:
		Number of			Weighted-			Weighted-			Aggregate
		Stock Options			Average			Average			Intrinsic
					Exercise			Remaining			Value
					Price			Contractual			(in thousands)
								Term
								(in years)
	Outstanding at December 31, 2013		3,846,168		$	4.14			7.43		$	76,189
	Granted		1,072,809			32.76
	Exercised		(912,783	)		1.14
	Forfeited/cancelled		(22,633	)		4.45
	Outstanding at June 30, 2014		3,983,561		$	12.54			7.85		$	132,591
	Exercisable at June 30, 2014		1,720,163		$	1.43			6.19		$	76,357
	Vested and expected to vest at June 30, 2014		3,297,987		$	11.77			7.62		$	112,303
	The weighted-average grant date fair value of options granted was $27.84, $6.88, $23.64 and $6.88 during the three months ended June 30, 2014 and 2013 and the six months ended June 30, 2014 and 2013, respectively. The total intrinsic value of options exercised was $10.7 million, $0.4 million, $34.8 million, and $0.4 million during the three months ended June 30, 2014 and 2013 and the six months ended June 30, 2014 and 2013, respectively.
	At June 30, 2014, the total unrecognized compensation expense related to unvested stock option awards, including estimated forfeitures, was $27.4 million, which the Company expects to recognize over a weighted-average period of approximately 3.2 years. The Company also has unrecognized stock-based compensation expense of $2.8 million related to stock options with performance-based vesting criteria that are not considered probable of achievement as of June 30, 2014; therefore the Company has not yet begun to recognize the expense on these awards.
	Restricted Stock and Early Exercise of Stock Options
	At June 30, 2014, there were 14,204 shares of unvested restricted stock which remain subject to the Company’s right of repurchase.
	Unvested restricted stock activity for the six months ended June 30, 2014 is summarized as follows:
		Six Months Ended
		June 30, 2014
	Unvested shares beginning of period		23,295
	Vested		(9,091	)
	Unvested shares end of period		14,204
	Performance-Based Stock Option Grants
	During the three and six months ended June 30, 2014, no options to purchase shares of common stock were granted to employees, including executive officers, which contain performance-based and service-based vesting criteria. During the three and six months ended June 30, 2013, the Company granted 355,454 shares of common stock, which contain performance-based and service-based vesting criteria. Performance-based vesting criteria for these options primarily relate to milestone events specific to the Company’s corporate goals, including but not limited to certain preclinical and clinical development milestones related to the Company’s product candidates. Stock-based compensation expense associated with these performance-based stock options is recognized if the performance condition is considered probable of achievement using management’s best estimates. Management assessed the probability of achieving the milestones and determined that certain performance-based milestones are probable of achievement as of June 30, 2014. The achievement of the remaining milestones were deemed to be not probable as of June 30, 2014. During the three months ended June 2014 and 2013 and six months ended June 2014 and 2013, the Company recognized stock-based compensation expense of $0.1 million, $0.1 million, $0.1 million, and $0.2 million, respectively, related to stock options with performance-based vesting criteria that are considered probable of achievement as of June 30, 2014.
	Stock-Based Compensation Expense
	During the three and six months ended June 30, 2014 and 2013, the Company recorded stock-based compensation expense for employee and non-employee stock options and restricted stock, which was allocated as follows in the condensed consolidated interim statements of operations (in thousands):
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Research and development expense	$	1,397		$	246		$	2,461		$	533
	General and administrative expense		984			83			1,425			220
		$	2,381		$	329		$	3,886		$	753
	The fair value of each stock option granted to employees is estimated on the date of grant and for non-employees on each vesting and reporting date using the Black-Scholes option-pricing model. The following table summarizes the weighted average assumptions used in calculating the fair value of the awards:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Risk-free interest rate		1.81	%		1	%		1.82	%		1	%
	Expected dividend yield		—			—			—			—
	Expected term (in years)		5.89			6.49			6.02			6.49
	Expected volatility		88	%		91.85	%		85.34	%		91.85	%
	2013 Employee stock purchase plan
	In June 2013, the Company’s Board of Directors adopted, and in July 2013 the Company’s stockholders approved, the 2013 Employee Stock Purchase Plan, or the 2013 ESPP. The 2013 ESPP will be administered by the Company’s Board of Directors or by a committee appointed by the Company’s Board of Directors. The 2013 ESPP initially provides participating employees with the opportunity to purchase up to an aggregate of 327,272 shares of the Company’s common stock. While approved, the plan has not yet been made available to employees and no shares have been issued under this plan as of June 30, 2014.

Income_Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2014
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	8. Income Taxes
	The provision (benefit) for income taxes is as follows for the three and six months ended June 30, 2014 and 2013 (in thousands):
		Three Months Ended June 30,				Six Months Ended June 30,
		2014		2013		2014		2013
	Current:
	Federal	$	—	$	99	$	—	$	289
	State		—		—		—		—
	Total current		—		99		—		289
	Deferred:
	Federal		—		—		—		—
	State		—		—		—		—
	Total deferred		—		—		—		—
	Total	$	—	$	99	$	—	$	289
	As required by ASC 740, Income Taxes (“ASC 740”), management of the Company has evaluated the positive and negative evidence bearing upon the realizability of the Company’s deferred tax assets, which are comprised principally of timing differences related to the recognition of revenue under the Celgene Agreement for financial statement versus tax purposes. During the year ended December 31, 2011, management determined that it was more likely than not that it would realize a portion of its deferred tax assets because of the Company’s ability to carryback future losses for U.S. federal income tax purposes. As a result, the Company reversed approximately $10.7 million of the valuation allowance on its deferred tax assets in the year ended December 31, 2011, representing the amount of deferred tax assets that would be realized in 2012 and 2013, the years available for carryback. The Company utilized certain of the deferred tax assets, including net operating losses, generated in the years ended December 31, 2013 and 2012 to reduce its federal income taxes payable each year. The provision for income taxes for the three and six months ended June 30, 2013 was attributable to penalties and interest accrued for the non-payment of U.S. federal income taxes.
	In January 2014, the Company paid $6.0 million as payment in full of its U.S. federal income tax liability related to the year ended December 31, 2011, including $1.5 million of interest and penalties accrued. The Company has filed a carryback claim to apply the net losses incurred during the year ended December 31, 2013 against the previous taxable income and expects to receive a refund of $3.8 million of the amounts paid in January 2014 after the filing of the Company’s 2013 tax return. In addition, the Company received an abatement from the Internal Revenue Service (IRS) of $0.7 million related to interest and penalties paid by the Company which was received during the three months ended June 30, 2014. The amount expected to be refunded by the IRS is recorded as refundable income taxes as of June 30, 2014.
	The Company applies the accounting guidance in ASC 740 related to accounting for uncertainty in income taxes. The Company’s reserves related to taxes are based on a determination of whether, and how much of, a tax benefit taken by the Company in its tax filings or positions is more likely than not to be realized following resolution of any potential contingencies present related to the tax benefit. As of June 30, 2014, the Company had no unrecognized tax benefits. The Company recognizes interest and penalties related to uncertain tax positions in the provision (benefit) for income taxes.

Net_Loss_per_Share_Applicable_

Net Loss per Share Applicable to Common Stockholders	6 Months Ended
	Jun. 30, 2014
Earnings Per Share [Abstract]	'
Net Loss per Share Applicable to Common Stockholders	'
	9. Net Loss per Share Applicable to Common Stockholders
	Basic net loss per share applicable to common stockholders is calculated by dividing net loss applicable to common stockholders by the weighted average shares outstanding during the period, without consideration for common stock equivalents. Net loss applicable to common stockholders is calculated by adjusting the net loss of the Company for cumulative preferred stock dividends for periods when preferred stock was outstanding. Diluted net loss per share applicable to common stockholders is calculated by adjusting weighted average shares outstanding for the dilutive effect of common stock equivalents outstanding for the period, determined using the treasury-stock method. For purposes of the dilutive net loss per share applicable to common stockholders calculation, preferred stock, stock options, and unvested restricted stock are considered to be common stock equivalents but are excluded from the calculation of diluted net loss per share applicable to common stockholders, as their effect would be anti-dilutive; therefore, basic and diluted net loss per share applicable to common stockholders were the same for all periods presented. The following common stock equivalents were excluded from the calculation of diluted net loss per share applicable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect:
		Three and Six Months Periods Ended June 30,
		2014		2013
	Convertible preferred stock		—		19,731,564
	Stock options		3,983,561		3,657,145
	Unvested restricted stock		14,204		63,840
			3,997,765		23,452,549

Subsequent_Events

Subsequent Events	6 Months Ended
	Jun. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	10. Subsequent Events
	In July 2014, the Company amended its collaboration agreement with Celgene. The amendment contemplates allowing more flexibility in the design and conduct of phase I clinical trials and additional nonclinical and/or clinical activities that the Company agrees to perform at Celgene’s request. The amendment further clarifies the mechanism and timing for payments to be made with respect to such development activities. The impact of the amendment on the co-commercialized and split licensed programs is summarized below:
	Co-Commercialized Licensed Programs: The amendment clarifies the timing of the one-time milestone payment for the development costs related to a phase I clinical trial to become due upon the earlier of the determination of the maximum tolerated dose or Celgene’s election to license the program.
	Split Licensed Programs: The amendment allows for the Company to receive in the form of a milestone payment reimbursement for costs and expenses it incurs for a disease-specific expansion cohort within a phase I clinical trial design, provided the disease-specific expansion cohort supports the initiation of a subsequent pivotal clinical trial. The milestone reimbursement is for 50% of the costs incurred by the Company up to $10 million and is payable upon the first patient dosed within the corresponding pivotal trial.
	The Company is currently evaluating the impact of the amendment on its consolidated financial statements for the quarter ending September 30, 2014.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies and Recent Accounting Pronouncements (Policies)	6 Months Ended
	Jun. 30, 2014
Accounting Policies [Abstract]	'
ASU 2014-12, Compensation-Stock Compensation (Topic 718)	'
	In June 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-12, Compensation—Stock Compensation (Topic 718). The ASU clarifies how entities should treat performance targets that can be achieved after the requisite service period of a share-based payment award. The accounting standard is effective for interim and annual periods beginning after December 15, 2015. The Company is currently in the process of evaluating the impact of the guidance on its financial position, results of operation, and cash flows.
ASU 2014-09, Revenue from Contracts with Customers (Topic 606)	'
	In May 2014, the FASB issued ASU 2014-09, Revenue from Contracts with Customers (Topic 606). The ASU provides for a single comprehensive model for use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance. The accounting standard is effective for interim and annual periods beginning after December 15, 2016 with no early adoption permitted. The Company is currently in the process of evaluating the impact of the guidance on its financial position, results of operation, and cash flows.
Recent Accounting Pronouncements	'
	Accounting standards that have been issued by the FASB or other standards-setting bodies that do not require adoption until a future date are not expected to have a material impact on the Company’s financial statements upon adoption.
Fair Value Measurements and Disclosures	'
	The Company records cash equivalents and marketable securities at fair value. Accounting Standards Codification (“ASC”) Topic 820, Fair Value Measurements and Disclosures, established a fair value hierarchy for those instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). The hierarchy consists of three levels:
	Level 1 – Unadjusted quoted prices in active markets for identical assets or liabilities.
	Level 2 – Quoted prices for similar assets and liabilities in active markets, quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liability.
	Level 3 – Unobservable inputs that reflect the Company’s own assumptions about the assumptions market participants would use in pricing the asset or liability in which there is little, if any, market activity for the asset or liability at the measurement date.
Investments - Debt and Equity Securities	'
	Marketable securities at June 30, 2014 and December 31, 2013 consisted primarily of investments in United States Treasuries and certificates of deposit. Management determines the appropriate classification of the securities at the time they are acquired and evaluates the appropriateness of such classifications at each balance sheet date. The Company classifies its marketable securities as available-for-sale pursuant to ASC 320, Investments – Debt and Equity Securities. Marketable securities are recorded at fair value, with unrealized gains and losses included as a component of accumulated other comprehensive loss in stockholders’ equity and a component of total comprehensive loss in the condensed consolidated interim statements of comprehensive loss, until realized. Realized gains and losses are included in investment income on a specific-identification basis. There were no realized gains or losses on marketable securities for the three or six months ended June 30, 2014 and 2013.
	The Company reviews marketable securities for other-than-temporary impairment whenever the fair value of a marketable security is less than the amortized cost and evidence indicates that a marketable security’s carrying amount is not recoverable within a reasonable period of time. Other-than-temporary impairments of investments are recognized in the condensed consolidated interim statements of operations if the Company has experienced a credit loss, has the intent to sell the marketable security, or if it is more likely than not that the Company will be required to sell the marketable security before recovery of the amortized cost basis. Evidence considered in this assessment includes reasons for the impairment, compliance with the Company’s investment policy, the severity and the duration of the impairment and changes in value subsequent to the end of the period.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2014
Fair Value Disclosures [Abstract]	'
Cash Equivalents and Marketable Securities Measured at Fair Value on a Recurring Basis	'
	The following table summarizes the cash equivalents and marketable securities measured at fair value on a recurring basis as of June 30, 2014 (in thousands):
		Level 1		Level 2		Level 3		Total
	Cash equivalents	$	105,084	$	480	$	—	$	105,564
	Marketable securities:
	Certificates of deposit		—		12,835		—		12,835
	U.S. Treasuries		140,029		—		—		140,029
		$	245,113	$	13,315	$	—	$	258,428
	The following table summarizes the cash equivalents and marketable securities measured at fair value on a recurring basis as of December 31, 2013 (in thousands):
		Level 1		Level 2		Level 3		Total
	Cash equivalents	$	68,792	$	—	$	—	$	68,792
	Marketable securities:
	Certificates of deposit		—		6,915		—		6,915
	U.S. Treasuries		115,419		—		—		115,419
		$	184,211	$	6,915	$	—	$	191,126

Marketable_Securities_Tables

Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2014
Investments Debt And Equity Securities [Abstract]	'
Marketable Securities	'
	Marketable securities at June 30, 2014 consist of the following (in thousands):
		Amortized Cost		Unrealized		Unrealized			Fair
				Gains		Losses			Value
	Current:
	Certificates of deposit	$	12,850	$	—	$	(15	)	$	12,835
	U.S. Treasuries		117,368		34		(4	)		117,398
	Non-current:
	U.S. Treasuries		22,634		2		(5	)		22,631
		$	152,852	$	36	$	(24	)	$	152,864
	Marketable securities at December 31, 2013 consist of the following (in thousands):
		Amortized Cost		Unrealized		Unrealized			Fair
				Gains		Losses			Value
	Current:
	Certificates of deposit	$	6,920	$	—	$	(5	)	$	6,915
	U.S. Treasuries		88,287		8		(1	)		88,294
	Non-current:
	U.S. Treasuries		27,113		12		—			27,125
		$	122,320	$	20	$	(6	)	$	122,334

Accrued_Expenses_and_Other_Cur1

Accrued Expenses and Other Current Liabilities (Tables)	6 Months Ended
	Jun. 30, 2014
Payables And Accruals [Abstract]	'
Summary of Accrued Expenses and Other Current Liabilities	'
	Accrued expenses and other current liabilities consist of the following (in thousands):
		June 30,		December 31,
		2014		2013
	Accrued compensation	$	2,371	$	3,642
	Accrued contracted research and development costs		2,372		2,484
	Accrued professional fees		620		320
	Accrued other		93		140
	Total	$	5,456	$	6,586

ShareBased_Payments_Tables

Share-Based Payments (Tables)	6 Months Ended
	Jun. 30, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'
Stock Award Activity	'
	The following table summarizes the activity of all stock incentive plans for the six months ended June 30, 2014:
		Number of			Weighted-			Weighted-			Aggregate
		Stock Options			Average			Average			Intrinsic
					Exercise			Remaining			Value
					Price			Contractual			(in thousands)
								Term
								(in years)
	Outstanding at December 31, 2013		3,846,168		$	4.14			7.43		$	76,189
	Granted		1,072,809			32.76
	Exercised		(912,783	)		1.14
	Forfeited/cancelled		(22,633	)		4.45
	Outstanding at June 30, 2014		3,983,561		$	12.54			7.85		$	132,591
	Exercisable at June 30, 2014		1,720,163		$	1.43			6.19		$	76,357
	Vested and expected to vest at June 30, 2014		3,297,987		$	11.77			7.62		$	112,303
Unvested Restricted Stock Activity	'
	Unvested restricted stock activity for the six months ended June 30, 2014 is summarized as follows:
		Six Months Ended
		June 30, 2014
	Unvested shares beginning of period		23,295
	Vested		(9,091	)
	Unvested shares end of period		14,204
Recorded Stock-Based Compensation Expense for Employee and Non-Employee Stock Options and Restricted Stock	'
	During the three and six months ended June 30, 2014 and 2013, the Company recorded stock-based compensation expense for employee and non-employee stock options and restricted stock, which was allocated as follows in the condensed consolidated interim statements of operations (in thousands):
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Research and development expense	$	1,397		$	246		$	2,461		$	533
	General and administrative expense		984			83			1,425			220
		$	2,381		$	329		$	3,886		$	753
Schedule of Fair Value Option Award Weighted Average Assumptions Used	'
	The following table summarizes the weighted average assumptions used in calculating the fair value of the awards:
		Three Months Ended June 30,						Six Months Ended June 30,
		2014			2013			2014			2013
	Risk-free interest rate		1.81	%		1	%		1.82	%		1	%
	Expected dividend yield		—			—			—			—
	Expected term (in years)		5.89			6.49			6.02			6.49
	Expected volatility		88	%		91.85	%		85.34	%		91.85	%

Income_Taxes_Tables

Income Taxes (Tables)	6 Months Ended
	Jun. 30, 2014
Income Tax Disclosure [Abstract]	'
Provision (Benefit) for Income Taxes	'
	The provision (benefit) for income taxes is as follows for the three and six months ended June 30, 2014 and 2013 (in thousands):
		Three Months Ended June 30,				Six Months Ended June 30,
		2014		2013		2014		2013
	Current:
	Federal	$	—	$	99	$	—	$	289
	State		—		—		—		—
	Total current		—		99		—		289
	Deferred:
	Federal		—		—		—		—
	State		—		—		—		—
	Total deferred		—		—		—		—
	Total	$	—	$	99	$	—	$	289

Net_Loss_per_Share_Applicable_1

Net Loss per Share Applicable to Common Stockholders (Tables)	6 Months Ended
	Jun. 30, 2014
Earnings Per Share [Abstract]	'
Common Stock Excluded from Calculation of Diluted Net Loss Per Share	'
	The following common stock equivalents were excluded from the calculation of diluted net loss per share applicable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect:
		Three and Six Months Periods Ended June 30,
		2014		2013
	Convertible preferred stock		—		19,731,564
	Stock options		3,983,561		3,657,145
	Unvested restricted stock		14,204		63,840
			3,997,765		23,452,549

Overview_and_Basis_of_Presenta1

Overview and Basis of Presentation - Additional Information (Detail) (USD $)	0 Months Ended	6 Months Ended		0 Months Ended	1 Months Ended	0 Months Ended	1 Months Ended	0 Months Ended	1 Months Ended	0 Months Ended	1 Months Ended
In Millions, except Share data, unless otherwise specified	Jul. 29, 2013	Jun. 30, 2014	Jun. 30, 2014	Jul. 29, 2013	Apr. 30, 2014	Jul. 29, 2013	31-May-14	Jul. 29, 2013	Apr. 30, 2014	Jul. 29, 2013	31-May-14
			Minimum [Member]	IPO [Member]	IPO [Member]	Underwriter [Member]	Underwriter [Member]	Private Placement [Member]	Private Placement [Member]	Private Placement [Member]	Private Placement [Member]
			Diseases		Subsequent Event [Member]		Subsequent Event [Member]		Subsequent Event [Member]	Celgene [Member]	Celgene [Member]
											Subsequent Event [Member]
Basis Of Presentation [Line Items]	'	'	'	'	'	'	'	'	'	'	'
Number of rare genetic disease under entity therapeutic group	'	'	600	'	'	'	'	'	'	'	'
Common stock shares purchased	'	'	'	6,772,221	2,000,000	883,333	300,000	708,333	294,800	'	'
Public offering price	'	'	'	$18	$44	'	'	$18	'	'	'
Net proceeds from the IPO	'	'	'	$111	$82.30	'	'	'	'	$12.80	$12.40
Reserve stock split	'	'1-for-2.75	'	'	'	'	'	'	'	'	'
Reverse stock split ratio	'	0.3636	'	'	'	'	'	'	'	'	'
Additional outstanding shares common stock	19,731,564	'	'	'	'	'	'	'	'	'	'

Fair_Value_Measurements_Cash_E

Fair Value Measurements - Cash Equivalents and Marketable Securities Measured at Fair Value on a Recurring Basis (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Marketable securities	$152,864	$122,334
Fair Value, Measurements, Recurring [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash equivalents	105,564	68,792
Cash equivalents and marketable securities, total	258,428	191,126
Fair Value, Measurements, Recurring [Member] | Certificates of deposit [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Marketable securities	12,835	6,915
Fair Value, Measurements, Recurring [Member] | U.S. Treasuries [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Marketable securities	140,029	115,419
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash equivalents	105,084	68,792
Cash equivalents and marketable securities, total	245,113	184,211
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | U.S. Treasuries [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Marketable securities	140,029	115,419
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Cash equivalents	480	'
Cash equivalents and marketable securities, total	13,315	6,915
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Certificates of deposit [Member]	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'
Marketable securities	$12,835	$6,915

Fair_Value_Measurements_Additi

Fair Value Measurements - Additional Information (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'	'
Financial assets or liabilities that were classified as Level 3	$0	'	$0
Transfers of assets from Level 1 to Level 2	0	0	'
Transfers of assets from Level 2 to Level 1	0	0	'
Transfers of liabilities from Level 1 to Level 2	0	0	'
Transfers of liabilities from Level 2 to Level 1	0	0	'
Level 3 [Member]	'	'	'
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]	'	'	'
Financial assets classified as Level 3	0	0	'
Financial liabilities classified as Level 3	$0	$0	'

Marketable_Securities_Addition

Marketable Securities - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014	Dec. 31, 2013
	Securities		Securities		Securities	Maximum [Member]	Maximum [Member]	Minimum [Member]	Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]	'	'	'	'	'	'	'	'	'
Realized gains or losses on marketable securities	$0	$0	$0	$0	'	'	'	'	'
Investment maturity period, non-current	'	'	'	'	'	'2 years	'2 years	'1 year	'1 year
Investment maturity period, current	'	'	'	'	'	'1 year	'1 year	'	'
Debt securities in an unrealized loss position	66	'	66	'	33	'	'	'	'
Aggregate fair value of debt securities in an unrealized loss position	$57,400,000	'	$57,400,000	'	$31,700,000	'	'	'	'
Securities in significant unrealized loss position	0	'	0	'	0	'	'	'	'

Marketable_Securities_Marketab

Marketable Securities - Marketable Securities (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	$152,852	$122,320
Unrealized Gains	36	20
Unrealized Losses	-24	-6
Fair Value	152,864	122,334
Current: [Member] | Certificates of deposit [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	12,850	6,920
Unrealized Losses	-15	-5
Fair Value	12,835	6,915
Current: [Member] | U.S. Treasuries [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	117,368	88,287
Unrealized Gains	34	8
Unrealized Losses	-4	-1
Fair Value	117,398	88,294
Non-Current: [Member] | U.S. Treasuries [Member]	'	'
Schedule of Available-for-sale Securities [Line Items]	'	'
Amortized Cost	22,634	27,113
Unrealized Gains	2	12
Unrealized Losses	-5	'
Fair Value	$22,631	$27,125

Collaboration_Agreements_Addit

Collaboration Agreements - Additional Information (Detail) (USD $)

0 Months Ended

1 Months Ended

3 Months Ended

6 Months Ended

12 Months Ended

1 Months Ended

6 Months Ended

Jul. 29, 2013

Dec. 31, 2013

Oct. 31, 2011

Apr. 30, 2010

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Dec. 31, 2013

31-May-14

Jul. 31, 2013

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Dec. 31, 2013

Jun. 30, 2014

Vendor

Celgene [Member]

Series B convertible preferred stock [Member]

Series B convertible preferred stock [Member]

Series B convertible preferred stock [Member]

Maximum [Member]

Maximum [Member]

Minimum [Member]

Licensed_Program

Celgene [Member]

Candidate

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

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Agreement amended date

'

'

'

'2011-10

'

'

'

'

'

'

'

'

'

'

'

'

Amended collaboration expiration date

'

'2015-04

'

'2014-04

'

'

'

'

'2015-04

'

'

'

'

'

'

'

Discovery phase years

'

'

'

'2 years

'

'

'

'

'

'

'

'

'

'

'

'

Term of the initial discovery period before amendment to extend

'

'4 years

'3 years

'

'

'

'

'

'4 years

'

'

'

'

'

'

'

Term of extended period after amendment of the initial discovery period

'

'5 years

'4 years

'

'

'

'

'

'5 years

'

'

'

'

'

'

'

Number of candidates confirmed by the Joint Research Committee

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

Portion of extension recognized in unbilled collaboration revenue

'

$5,000,000

'

'

'

'

'

'

$5,000,000

'

'

'

'

'

'

'

Number of licensed programs type under collaboration agreements

'

'

'

'

'

'

3

'

'

'

'

'

'

'

'

'

Period considered for agreement termination notice

'

'

'

'

'

'

'30 days

'

'

'

'

'

'

'

'

'

Upfront payment received

'

'

'

'

'

'

121,200,000

'

'

'

'

'

'

'

'

'

Series B convertible preferred stock, purchased

'

0

'

'

0

'

0

'

0

'

'

'

5,190,551

'

'

'

Series B convertible preferred stock price per share

'

'

'

'

'

'

'

'

'

'

'

$1.70

'

'

'

'

Net proceeds of Series B convertible preferred stock

'

'

'

'

'

'

'

'

'

'

'

8,800,000

'

'

'

'

Additional consideration under agreement

'

'

'

'

'

'

'

'

'

'

'

3,100,000

'

'

'

'

Series B convertible preferred stock at fair value

'

'

'

'

'

'

'

'

'

'

'

5,700,000

'

'

'

'

Reserve stock split

'

'

'

'

'

'

'1-for-2.75

'

'

'

'

'1-for-2.75

'

'

'

'

Reserve stock split ratio

'

'

'

'

'

'

0.3636

'

'

'

'

0.3636

'

'

'

'

Additional outstanding shares common stock

19,731,564

'

'

'

'

'

'

'

'

'

1,887,473

'

'

'

'

'

Number of vendors selling similar competitive products

'

'

'

'

'

'

0

'

'

'

'

'

'

'

'

'

Revenue to be recognized from performance obligations

'

'

'

'

'

'

124,300,000

'

'

'

'

'

'

'

'

'

Number of years company expected to fulfill its performance obligations

'

'

'

'

'

'

'6 years

'

'

'

'

'

'

'

'

'

Payment made in pursuant to the amendment

'

'

20,000,000

'

'

'

'

'

'

20,000,000

'

'

'

'

'

'

Recognized revenue to extension

'

'

'

'

2,100,000

'

4,300,000

'

500,000

'

'

'

'

'

'

'

Eligible payment to be received from extension of the discovery phase

'

'

'

'

'

'

'

'

'

'

'

'

'

'

20,000,000

'

Date of extension of discovery phase

'

'2016-04

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Revenue

'

'

'

'

8,400,000

6,300,000

16,800,000

12,500,000

'

'

'

'

'

'

'

'

Receipts of potential milestone payments

'

'

'

'

'

'

'

'

'

'

'

'

'

120,000,000

'

'

Milestone payment upon achievement of a specified clinical development milestone event

'

'

'

'

'

'

'

'

'

'

'

'

'

25,000,000

'

'

Milestone payments upon achievement of specified regulatory milestone events

'

'

'

'

'

'

'

'

'

'

'

'

'

70,000,000

'

'

Milestone payment upon achievement of a specified commercial milestone event

'

'

'

'

'

'

'

'

'

'

'

'

'

25,000,000

'

'

Achievement of an early clinical development milestone event

'

'

'

'

22,500,000

'

22,500,000

'

'

'

'

'

'

'

'

'

Dosing of the last patient in a Company-sponsored

'

'

'

'

25,000,000

'

25,000,000

'

'

'

'

'

'

'

'

'

Potential milestone that the Company might be entitled to receive enrollment of the last patient

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

5,000,000

Milestone or royalty payments received

'

'

'

'

'

'

$0

'

'

'

'

'

'

'

'

'

Accrued_Expenses_and_Other_Cur2

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Detail) (USD $)	Jun. 30, 2014	Dec. 31, 2013
In Thousands, unless otherwise specified
Payables And Accruals [Abstract]	'	'
Accrued compensation	$2,371	$3,642
Accrued contracted research and development costs	2,372	2,484
Accrued professional fees	620	320
Accrued other	93	140
Total	$5,456	$6,586

ShareBased_Payments_Additional

Share-Based Payments - Additional Information (Detail) (USD $)

3 Months Ended

6 Months Ended

0 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jan. 01, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2014

Jun. 30, 2013

Jun. 30, 2013

Jun. 30, 2013

2013 Stock Incentive Plan [Member]

2013 Stock Incentive Plan [Member]

2013 Stock Incentive Plan [Member]

2013 Stock Incentive Plan [Member]

2013 Stock Incentive Plan [Member]

2013 Stock Incentive Plan [Member]

2013 Stock Incentive Plan [Member]

2013 Stock Incentive Plan [Member]

2013 Stock Incentive Plan [Member]

Maximum [Member]

Performance-Based Stock Option Grants [Member]

Performance-Based Stock Option Grants [Member]

Performance-Based Stock Option Grants [Member]

Performance-Based Stock Option Grants [Member]

Stock Option Grant [Member]

Stock Option Grant [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

Common stock reserved for issuance

'

'

'

'

'

4,831,387

'

'

'

'

'

'

'

Shares available for future issuance

'

'

'

'

'

847,826

'

'

'

'

'

'

'

Common stock

'

'

'

'

'

'

2,000,000

'

'

'

'

'

'

Common stock outstanding

'

'

'

'

'

'

4.00%

'

'

'

'

'

'

Shares authorized for issuance

'

'

'

'

1,242,966

'

'

'

'

'

'

'

'

Weighted-average grant date fair value of options

$27.84

$6.88

$23.64

$6.88

'

'

'

'

'

'

'

'

'

Intrinsic value of options exercised

$10,700,000

$400,000

$34,800,000

$400,000

'

'

'

'

'

'

'

'

'

Unrecognized compensation expense related to stock option

'

'

'

'

'

27,400,000

'

2,800,000

'

2,800,000

'

'

'

Weighted-average period to recognize compensation expense

'

'

'

'

'

'3 years 2 months 12 days

'

'

'

'

'

'

'

Unvested restricted stock

'

'

'

'

'

14,204

'

'

'

'

'

'

'

Stock options granted

'

'

1,072,809

'

'

'

'

0

'

0

'

355,454

355,454

Stock-based compensation expense

$2,381,000

$329,000

$3,886,000

$753,000

'

'

'

$100,000

$100,000

$100,000

$200,000

'

'

Opportunity to purchase of common stock

'

'

327,272

'

'

'

'

'

'

'

'

'

'

Number of shares issued

'

'

0

'

'

'

'

'

'

'

'

'

'

ShareBased_Payments_Stock_Awar

Share-Based Payments - Stock Award Activity (Detail) (USD $)	6 Months Ended	12 Months Ended
In Thousands, except Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'
Number of Stock Options, Outstanding, Beginning balance	3,846,168	'
Number of Stock Options, Granted	1,072,809	'
Number of Stock Options, Exercised	-912,783	'
Number of Stock Options, Forfeited/cancelled	-22,633	'
Number of Stock Options, Outstanding, Ending balance	3,983,561	3,846,168
Number of Stock Options, Exercisable	1,720,163	'
Number of Stock Options, Vested and expected to vest	3,297,987	'
Weighted-Average Exercise Price, Outstanding, Beginning balance	$4.14	'
Weighted-Average Exercise Price, Granted	$32.76	'
Weighted-Average Exercise Price, Exercised	$1.14	'
Weighted-Average Exercise Price, Forfeited/cancelled	$4.45	'
Weighted-Average Exercise Price, Outstanding, Ending balance	$12.54	$4.14
Weighted-Average Exercise Price, Exercisable	$1.43	'
Weighted-Average Exercise Price, Vested and expected to vest	$11.77	'
Weighted-Average Remaining Contractual Term (in years), Outstanding	'7 years 10 months 6 days	'7 years 5 months 5 days
Weighted-Average Remaining Contractual Term (in years), Exercisable	'6 years 2 months 9 days	'
Weighted-Average Remaining Contractual Term (in years), Vested and expected to vest	'7 years 7 months 13 days	'
Aggregate Intrinsic Value, Outstanding, Beginning balance	$76,189	'
Aggregate Intrinsic Value, Outstanding, Ending balance	132,591	76,189
Aggregate Intrinsic Value, Exercisable	76,357	'
Aggregate Intrinsic Value, Vested and expected to vest	$112,303	'

ShareBased_Payments_Unvested_R

Share-Based Payments - Unvested Restricted Stock Activity (Detail) (Restricted stock [Member])	6 Months Ended
	Jun. 30, 2014
Restricted stock [Member]	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'
Unvested shares beginning of period	23,295
Vested	-9,091
Unvested shares end of period	14,204

ShareBased_Payments_Recorded_S

Share-Based Payments - Recorded Stock-Based Compensation Expense for Employee and Non-Employee Stock Options and Restricted Stock (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Allocated share based compensation expense	$2,381	$329	$3,886	$753
Research and development expense [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Allocated share based compensation expense	1,397	246	2,461	533
General and administrative expense [Member]	'	'	'	'
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]	'	'	'	'
Allocated share based compensation expense	$984	$83	$1,425	$220

ShareBased_Payments_Schedule_o

Share-Based Payments - Schedule of Fair Value Option Award Weighted Average Assumptions Used (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]	'	'	'	'
Risk-free interest rate	1.81%	1.00%	1.82%	1.00%
Expected dividend yield	'	'	'	'
Expected term (in years)	'5 years 10 months 21 days	'6 years 5 months 27 days	'6 years 7 days	'6 years 5 months 27 days
Expected volatility	88.00%	91.85%	85.34%	91.85%

Income_Taxes_Provision_Benefit

Income Taxes - Provision (Benefit) for Income Taxes (Detail) (USD $)	3 Months Ended		6 Months Ended
In Thousands, unless otherwise specified	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Current:	'	'	'	'
Federal	'	$99	'	$289
State	'	'	'	'
Total current	'	99	'	289
Deferred:	'	'	'	'
Federal	'	'	'	'
State	'	'	'	'
Total deferred	'	'	'	'
Total	'	$99	'	$289

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	1 Months Ended	6 Months Ended
	Jan. 31, 2014	Jun. 30, 2014	Dec. 31, 2011
Income Tax Disclosure [Abstract]	'	'	'
Amount of valuation allowance on deferred tax assets	'	'	$10,700,000
Income tax liability paid	5,958,000	5,958,000	'
Interest and penalties paid	1,500,000	'	'
Receive a refund from tax return	3,800,000	'	'
Receive interest and penalties	'	700,000	'
Unrecognized tax benefits	'	$0	'

Recovered_Sheet1

Net Loss Per Share Applicable to Common Stockholders - Common Stock Excluded from Calculation of Diluted Net Loss Per Share (Detail)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Antidilutive securities excluded from computation of earnings per share	3,997,765	23,452,549
Convertible preferred stock [Member]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Antidilutive securities excluded from computation of earnings per share	'	19,731,564
Stock options [Member]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Antidilutive securities excluded from computation of earnings per share	3,983,561	3,657,145
Restricted stock [Member]	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'
Antidilutive securities excluded from computation of earnings per share	14,204	63,840

Subsequent_Events_Additional_I

Subsequent Events - Additional Information (Detail) (Subsequent Event [Member], USD $)	0 Months Ended
In Millions, unless otherwise specified	Jul. 31, 2014	Jul. 31, 2014
Subsequent Event [Member]	'	'
Subsequent Event [Line Items]	'	'
Percentage of costs incurred milestone reimbursement	50.00%	'
Potential milestone reimbursement amount	'	$10