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Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Jun. 30, 2013	Jul. 29, 2013
Document and Entity Information
Entity Registrant Name	Celldex Therapeutics, Inc.
Entity Central Index Key	0000744218
Document Type	10-Q
Document Period End Date	Jun. 30, 2013
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		80,987,871
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2013	Dec. 31, 2012
Current Assets:
Cash and Cash Equivalents	$ 25,900	$ 24,897
Marketable Securities	129,083	59,065
Accounts and Other Receivables	12	44
Prepaid and Other Current Assets	1,435	1,108
Total Current Assets	156,430	85,114
Property and Equipment, Net	7,338	7,205
Intangible Assets, Net	23,326	23,833
Other Assets	174	424
Goodwill	8,965	8,965
Total Assets	196,233	125,541
Current Liabilities:
Accounts Payable	2,069	745
Accrued Expenses	9,904	10,960
Current Portion of Long-Term Liabilities	530	388
Current Portion of Term Loan		5,592
Total Current Liabilities	12,503	17,685
Term Loan, less Current Portion		5,746
Other Long-Term Liabilities	6,636	6,336
Total Liabilities	19,139	29,767
Commitments and Contingent Liabilities (Note 13)
Stockholders' Equity:
Convertible Preferred Stock, $.01 Par Value; 3,000,000 Shares Authorized; No Shares Issued and Outstanding at June 30, 2013 and December 31, 2012
Common Stock, $.001 Par Value; 297,000,000 Shares Authorized; 80,977,696 and 64,359,513 Shares Issued and Outstanding at June 30, 2013 and December 31, 2012, respectively	81	64
Additional Paid-In Capital	474,942	357,094
Accumulated Other Comprehensive Income	2,548	2,745
Accumulated Deficit	(300,477)	(264,129)
Total Stockholders' Equity	177,094	95,774
Total Liabilities and Stockholders' Equity	$ 196,233	$ 125,541

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Jun. 30, 2013	Dec. 31, 2012
CONDENSED CONSOLIDATED BALANCE SHEETS
Convertible Preferred Stock, Par Value (in dollars per share)	$ 0.01	$ 0.01
Convertible Preferred Stock, Shares Authorized	3,000,000	3,000,000
Convertible Preferred Stock, Shares Issued	0	0
Convertible Preferred Stock, Shares Outstanding	0	0
Common Stock, Par Value (in dollars per share)	$ 0.001	$ 0.001
Common Stock, Shares Authorized	297,000,000	297,000,000
Common Stock, Shares Issued	80,977,696	64,359,513
Common Stock, Shares Outstanding	80,977,696	64,359,513

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
REVENUE:
Product Development and Licensing Agreements	$ 47	$ 40	$ 77	$ 75
Contracts and Grants	50	96	100	149
Product Royalties		1,873	2,334	4,218
Total Revenue	97	2,009	2,511	4,442
OPERATING EXPENSE:
Research and Development	15,090	11,114	29,180	21,881
Royalty		1,873	2,334	4,218
General and Administrative	3,411	2,219	6,549	4,536
Amortization of Acquired Intangible Assets	254	291	507	583
Total Operating Expense	18,755	15,497	38,570	31,218
Operating Loss	(18,658)	(13,488)	(36,059)	(26,776)
Investment and Other Income, Net	161	126	540	331
Interest Expense	(519)	(411)	(829)	(844)
Net Loss	$ (19,016)	$ (13,773)	$ (36,348)	$ (27,289)
Basic and Diluted Net Loss Per Common Share (Note 3) (in dollars per share)	$ (0.24)	$ (0.23)	$ (0.47)	$ (0.50)
Shares Used in Calculating Basic and Diluted Net Loss per Share (Note 3) (in shares)	80,899	58,733	77,482	54,439
COMPREHENSIVE LOSS:
Net Loss	$ (19,016)	$ (13,773)	$ (36,348)	$ (27,289)
Other Comprehensive (Loss) Income:
Foreign Currency Translation Adjustments	(1)	(1)	(3)	1
Unrealized (Loss) Gain on Marketable Securities	(140)	(39)	(194)	69
Comprehensive Loss	$ (19,157)	$ (13,813)	$ (36,545)	$ (27,219)

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash Flows from Operating Activities:
Net Loss	$ (36,348)	$ (27,289)
Adjustments to Reconcile Net Loss to Net Cash Used in Operating Activities:
Depreciation and Amortization	943	1,073
Amortization of Intangible Assets	507	583
Amortization and Premium of Marketable Securities	(1,949)	(157)
Realized Gain on Sales and Maturities of Marketable Securities		(6)
Gain on Sale or Disposal of Assets	(21)	(12)
Stock-Based Compensation Expense	1,384	1,088
Non-Cash Interest Expense	97	111
Changes in Operating Assets and Liabilities:
Accounts and Other Receivables	32	109
Prepaid and Other Current Assets	(424)	(493)
Other Assets	250	(99)
Accounts Payable and Accrued Expenses	109	(993)
Other Liabilities	162	573
Net Cash Used in Operating Activities	(35,258)	(25,512)
Cash Flows from Investing Activities:
Sales and Maturities of Marketable Securities	20,582	20,919
Purchases of Marketable Securities	(88,845)	(39,383)
Acquisition of Property and Equipment	(917)	(122)
Proceeds from Sale or Disposal of Assets	21	156
Net Cash Used in Investing Activities	(69,159)	(18,430)
Cash Flows from Financing Activities:
Net Proceeds from Stock Issuances	114,187	51,957
Proceeds from Issuance of Stock from Employee Benefit Plans	2,294
Payments of Term Loan	(11,029)	(1,323)
Payments of Other Liabilities	(29)	(29)
Net Cash Provided by Financing Activities	105,423	50,605
Effect of Exchange Rate Changes on Cash and Cash Equivalents	(3)	1
Net Increase in Cash and Cash Equivalents	1,003	6,664
Cash and Cash Equivalents at Beginning of Period	24,897	11,899
Cash and Cash Equivalents at End of Period	$ 25,900	$ 18,563

Basis of Presentation	6 Months Ended
Basis of Presentation	Jun. 30, 2013
Basis of Presentation
Basis of Presentation	(1) Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared by Celldex Therapeutics, Inc. (the “Company” or “Celldex”) in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and reflect the operations of the Company and its wholly-owned subsidiary. All intercompany transactions have been eliminated in consolidation. These interim financial statements do not include all the information and footnotes required by U.S. GAAP for annual financial statements and should be read in conjunction with the audited financial statements for the year ended December 31, 2012, which are included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission (“SEC”) on March 8, 2013. In the opinion of management, the interim financial statements reflect all normal recurring adjustments necessary to fairly state the Company’s financial position and results of operations for the interim periods presented. The year-end consolidated balance sheet data presented for comparative purposes was derived from audited financial statements, but does not include all disclosures required by U.S. GAAP. The results of operations for the interim periods are not necessarily indicative of the results of operations to be expected for any future interim period or the fiscal year ending December 31, 2013. At June 30, 2013, the Company had cash, cash equivalents and marketable securities of $155.0 million and working capital of $143.9 million. The Company incurred a loss of $36.3 million for the six months ended June 30, 2013. Net cash used in operations for the six months ended June 30, 2013 was $35.3 million. The Company believes that the cash, cash equivalents and marketable securities at June 30, 2013 will be sufficient to meet estimated working capital requirements and fund planned operations for at least the next twelve months. During the next twelve months, the Company may take further steps to raise additional capital to meet its long-term liquidity needs. These capital raising activities may include, but may not be limited to, one or more of the following: the licensing of technology programs with existing or new collaborative partners, possible business combinations, issuance of debt, or the issuance of common stock or other securities via private placements or public offerings. While the Company continues to seek capital through a number of means, there can be no assurance that additional financing will be available on acceptable terms, if at all, and the Company’s negotiating position in capital-raising efforts may worsen as existing resources are used. There is also no assurance that the Company will be able to enter into further collaborative relationships. Additional equity financing may be dilutive to the Company’s stockholders; debt financing, if available, may involve significant cash payment obligations and covenants that restrict the Company’s ability to operate as a business; and licensing or strategic collaborations may result in royalties or other terms which reduce the Company’s economic potential from products under development.

Significant Accounting Policies	6 Months Ended
Significant Accounting Policies	Jun. 30, 2013
Significant Accounting Policies
Significant Accounting Policies	(2) Significant Accounting Policies The significant accounting policies used in preparation of these condensed consolidated financial statements for the six months ended June 30, 2013 are consistent with those discussed in Note 2 to the consolidated financial statements in our Annual Report on Form 10-K for the year ended December 31, 2012, except for the adoption of new accounting standards during the first six months of 2013 as discussed below. Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial position or results of operations upon adoption. In January 2013, the Company adopted a new U.S. GAAP accounting standard which amended guidance applicable to annual impairment tests of indefinite-lived intangible assets. The amended guidance added an optional qualitative assessment for determining whether an indefinite-lived intangible asset is impaired. Prior to this guidance, companies were required to perform an annual impairment test that included a calculation of the fair value of the asset and a comparison of that fair value with its carrying value. If the carrying value exceeded the fair value, an impairment was recorded. The amended guidance allows a company the option to perform a qualitative assessment, considering both negative and positive evidence, regarding the potential impairment of the indefinite-lived intangible asset. If, based on the qualitative analysis, the company determines that it is more likely than not that the fair value of such an asset exceeds its carrying value, the company would be permitted to conclude that the indefinite-lived intangible asset was not impaired without a quantitative calculation of the fair value of the asset. Otherwise, the company would perform the quantitative calculation of the fair value and the comparison with the carrying value. The Company’s adoption of this new standard did not have a material effect on its operating results or financial position.

Net Loss Per Share

6 Months Ended

Jun. 30, 2013

Net Loss Per Share

Net Loss Per Share

(3) Net Loss Per Share

Basic net loss per common share is based upon the weighted-average number of common shares outstanding during the period, excluding restricted stock that has been issued but is not yet vested. Diluted net loss per common share is based upon the weighted-average number of common shares outstanding during the period plus additional weighted-average potentially dilutive common shares outstanding during the period when the effect is dilutive. The potentially dilutive common shares that have not been included in the net loss per common share calculations because the effect would have been anti-dilutive are as follows:

	Six months ended June 30,
	2013	2012

Stock options	5,005,603	4,304,897
Restricted stock	12,000	12,000
	5,017,603	4,316,897

Comprehensive Loss

6 Months Ended

Jun. 30, 2013

Comprehensive Loss

Comprehensive Loss

(4) Comprehensive Loss

In January 2013, the Company adopted a new U.S. GAAP accounting standard which requires the Company to separately disclose, on a prospective basis, the change in each component of other comprehensive income (loss) relating to reclassification adjustments and current period other comprehensive income (loss). As the new guidance relates to presentation only, the adoption did not have a material impact on the Company’s results of operations, financial position or cash flows. No amounts were reclassified out of accumulated other comprehensive income during the three or six months ended June 30, 2013. The changes in accumulated other comprehensive income (loss) by component for the three and six months ended June 30, 2013 are summarized below.

	Unrealized Gain (Loss) on Marketable Securities, net of tax			Foreign Currency Items			Total
	(In thousands)
Balance at March 31, 2013	$	102		$	2,587		$	2,689
Other comprehensive income (loss) before reclassifications	(140		)	(1		)	(141		)
Amounts reclassified from other comprehensive income	—			—			—
Net current-period other comprehensive income	(140		)	(1		)	(141		)
Balance at June 30, 2013	$	(38	)	$	2,586		$	2,548

Balance at December 31, 2012	$	156		$	2,589		$	2,745
Other comprehensive income (loss) before reclassifications	(194		)	(3		)	(197		)
Amounts reclassified from other comprehensive income	—			—			—
Net current-period other comprehensive income	(194		)	(3		)	(197		)
Balance at June 30, 2013	$	(38	)	$	2,586		$	2,548

- Definition

The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.

+ References

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+ Details

Fair Value Measurements

6 Months Ended

Jun. 30, 2013

Fair Value Measurements

Fair Value Measurements

(5) Fair Value Measurements

The following tables set forth the Company’s financial assets subject to fair value measurements:

	As of June 30, 2013		Level 1		Level 2		Level 3
	(In thousands)
Money market funds and cash equivalents	$	22,709	$	22,709	—		—
Marketable securities	$	129,083	—		$	129,083	—
	$	151,792	$	22,709	$	129,083	—

	As of December 31, 2012		Level 1		Level 2		Level 3
	(In thousands)
Money market funds and cash equivalents	$	18,688	$	18,688	—		—
Marketable securities	$	59,065	—		$	59,065	—
	$	77,753	$	18,688	$	59,065	—

There have been no transfers of assets or liabilities between the fair value measurement classifications. The Company’s financial instruments consist mainly of cash and cash equivalents, marketable securities, short-term accounts receivable, accounts payable and debt obligations. The Company values its marketable securities utilizing independent pricing services which normally derive security prices from recently reported trades for identical or similar securities, making adjustments based on significant observable transactions. At each balance sheet date, observable market inputs may include trade information, broker or dealer quotes, bids, offers or a combination of these data sources. Short-term accounts receivable and accounts payable are reflected in the accompanying consolidated financial statements at cost, which approximates fair value due to the short-term nature of these instruments.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

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+ Details

Marketable Securities

6 Months Ended

Jun. 30, 2013

Marketable Securities

Marketable Securities

(6) Marketable Securities

A summary of marketable securities is shown below:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(In thousands)
June 30, 2013
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	34,189	$	15	$	5	$	34,199
Maturing after one year through three years	34,030		61		22		34,069
Total U.S. government and municipal obligations	$	68,219	$	76	$	27	$	68,268
Corporate debt securities
Maturing in one year or less	$	33,336	$	10	$	32	$	33,314
Maturing after one year through three years	27,566		—		65		27,501
Total corporate debt securities	$	60,902	$	10	$	97	$	60,815
Total marketable securities	$	129,121	$	86	$	124	$	129,083

December 31, 2012
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	15,566	$	28	$	—	$	15,594
Maturing after one year through three years	19,797		99		1		19,895
Total U.S. government and municipal obligations	$	35,363	$	127	$	1	$	35,489
Corporate debt securities
Maturing in one year or less	$	17,353	$	23	$	4	$	17,372
Maturing after one year through three years	6,193		14		3		6,204
Total corporate debt securities	$	23,546	$	37	$	7	$	23,576
Total marketable securities	$	58,909	$	164	$	8	$	59,065

The marketable securities held by the Company were high investment grade and there were no marketable securities that the Company considered to be other-than-temporarily impaired as of June 30, 2013.

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References

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Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 115
-Paragraph 3, 19, 20, 21, 22, 137
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Intangible Assets and Goodwill

6 Months Ended

Jun. 30, 2013

Intangible Assets and Goodwill

Intangible Assets and Goodwill

(7) Intangible Assets and Goodwill

Intangible assets, net of accumulated amortization, and goodwill are as follows:

		June 30, 2013							December 31, 2012
	Estimated Life	Cost		Accumulated Amortization			Net		Cost		Accumulated Amortization			Net
	(In thousands)
Intangible Assets:
IPR&D	Indefinite	$	11,800	—			$	11,800	$	11,800	—			$	11,800
Amgen Amendment	16 years	14,500		$	(3,363	)	11,137		14,500		$	(2,915	)	11,585
Core Technology	11 years	1,296		(907		)	389		1,296		(848		)	448
Total Intangible Assets		$	27,596	$	(4,270	)	$	23,326	$	27,596	$	(3,763	)	$	23,833
Goodwill	Indefinite	$	8,965	—			$	8,965	$	8,965	—			$	8,965

The IPR&D intangible asset was recorded in connection with the acquisition of CuraGen and relates to the development of CDX-011. At the date of acquisition and at June 30, 2013, CDX-011 had not yet reached technological feasibility nor did it have any alternative future use. The Company recently completed a randomized Phase 2b study of CDX-011 for the treatment of advanced breast cancer.

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Term Loan	6 Months Ended
Term Loan	Jun. 30, 2013
Term Loan
Term Loan	(8) Term Loan In December 2010, the Company entered into a Loan and Security Agreement (the “Loan Agreement”) with MidCap Financial, LLC pursuant to which the Company borrowed $10 million (the “Term Loan”) from MidCap. In March 2011, the Company amended the Loan Agreement and borrowed an additional $5 million from General Electric Capital Corporation to increase the amount owed under the Term Loan to $15 million. In March 2012, the Company amended the Loan Agreement to extend the maturity date from December 2013 to December 2014. In May 2013, the Company elected to prepay the Term Loan in full, pursuant to the terms of the Loan Agreement, as amended, and paid $8.8 million in principal and $0.7 million in interest, prepayment and final payment fees. The Company’s obligations under the Loan Agreement had been secured by a first priority security interest in substantially all of its assets, other than its intellectual property. In connection with the repayment of the Term Loan and the termination of the Loan Agreement, those security interests were released. Interest expense on the Term Loan was $0.5 million and $0.8 million for the three and six months ended June 30, 2013 and $0.4 million and $0.8 million for the three and six months ended June 30, 2012, respectively.

Other Long-Term Liabilities

6 Months Ended

Jun. 30, 2013

Other Long-Term Liabilities

Other Long-Term Liabilities

(9) Other Long-Term Liabilities

Other long-term liabilities include the following:

	June 30, 2013			December 31, 2012
	(In thousands)
Deferred Rent	$	422		$	434
Net Deferred Tax Liability related to IPR&D	4,661			4,661
Deferred Income from Sale of Tax Benefits	1,630			1,118
Loan Payable	443			472
Other	10			39
Total	7,166			6,724
Less Current Portion	(530		)	(388		)
Long-Term Portion	$	6,636		$	6,336

In January 2013, 2012 and 2011, the Company received approval from the New Jersey Economic Development Authority and agreed to sell New Jersey tax benefits worth $0.8 million, $0.8 million and $0.6 million to an independent third party for $0.8 million, $0.7 million and $0.5 million, respectively. Under the agreement, the Company must maintain a base of operations in New Jersey for five years or the tax benefits must be paid back on a pro-rata basis based on the number of years completed. During the six months ended June 30, 2013 and 2012, the Company recorded $0.2 million and $0.1 million to other income related to the sale of these tax benefits, respectively.

Stockholders' Equity	6 Months Ended
Stockholders' Equity	Jun. 30, 2013
Stockholders' Equity
Stockholders' Equity	(10) Stockholders’ Equity In January 2011, the Company entered into a controlled equity offering sales agreement (the “Cantor Agreement”) with Cantor Fitzgerald & Co. pursuant to which the Company could issue and sell up to 5,000,000 shares of its common stock from time to time through Cantor, acting as agent. During the six months ended June 30, 2012, the Company issued 2,450,000 shares of common stock under the Cantor Agreement and raised $8.5 million in net proceeds. In September 2012, the Company and Cantor amended the Cantor Agreement (the “Cantor Amendment”) to allow the Company to issue and sell additional shares of its common stock having an aggregate offering price of up to $44.0 million. Under the Cantor Amendment, the Company will pay Cantor a fixed commission rate of 3.0% of the gross sales price per share of any common stock sold through Cantor. The Cantor Amendment terminates upon ten day notice by either Cantor or the Company. During the six months ended June 30, 2013, the Company issued 2,433,608 shares under the Cantor Amendment and raised $17.1 million in net proceeds. At June 30, 2013, the Company had $4.4 million remaining in aggregate offering price available under the Cantor Amendment. During the six months ended June 30, 2012, the Company issued 12,075,000 shares of its common stock in an underwritten public offering, including the underwriter’s exercise of their full over-allotment option to purchase an additional 1,575,000 shares of common stock. The net proceeds to the Company were $43.4 million, after deducting underwriting fees and offering expenses. During the six months ended June 30, 2013, the Company issued 13,800,000 shares of its common stock in an underwritten public offering, including the underwriter’s exercise of their full over-allotment option to purchase an additional 1,800,000 shares of common stock. The net proceeds to the Company were $97.0 million, after deducting underwriting fees and offering expenses.

- Definition

The entire disclosure for shareholders' equity, comprised of portions attributable to the parent entity and noncontrolling interest, if any, including other comprehensive income (as applicable). Including, but not limited to: (1) balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings; (2) accumulated balance for each classification of other comprehensive income and total amount of comprehensive income; (3) amount and nature of changes in separate accounts, including the number of shares authorized and outstanding, number of shares issued upon exercise and conversion, and for other comprehensive income, the adjustments for reclassifications to net income; (4) rights and privileges of each class of stock authorized; (5) basis of treasury stock, if other than cost, and amounts paid and accounting treatment for treasury stock purchased significantly in excess of market; (6) dividends paid or payable per share and in the aggregate for each class of stock for each period presented; (7) dividend restrictions and accumulated preferred dividends in arrears (in aggregate and per share amount); (8) retained earnings appropriations or restrictions, such as dividend restrictions; (9) impact of change in accounting principle, initial adoption of new accounting principle and correction of an error in previously issued financial statements; (10) shares held in trust for Employee Stock Ownership Plan (ESOP); (11) deferred compensation related to issuance of capital stock; (12) note received for issuance of stock; (13) unamortized discount on shares; (14) description, terms, and number of warrants or rights outstanding; (15) shares under subscription and subscription receivables, effective date of new retained earnings after quasi-reorganization and deficit eliminated by quasi-reorganization and, for a period of at least ten years after the effective date, the point in time from which the new retained dates; and (16) retroactive effective of subsequent change in capital structure.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
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-Paragraph 1
-Subparagraph (SX 210.4-08.(d),(e))
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-Publisher AICPA
-Name Accounting Research Bulletin (ARB)
-Number 43
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-Chapter 1
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher SEC
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-Number 210
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-Paragraph d
-Article 4

Reference 18: http://www.xbrl.org/2003/role/presentationRef
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-Number 210
-Section 02
-Paragraph 29, 30, 31
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Reference 19: http://www.xbrl.org/2003/role/presentationRef
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Reference 20: http://www.xbrl.org/2003/role/presentationRef
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Reference 21: http://www.xbrl.org/2003/role/presentationRef
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Reference 22: http://www.xbrl.org/2003/role/presentationRef
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Reference 23: http://www.xbrl.org/2003/role/presentationRef
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-Article 3

+ Details

Stock-Based Compensation

6 Months Ended

Jun. 30, 2013

Stock-Based Compensation

Stock-Based Compensation

(11) Stock-Based Compensation

A summary of stock option activity for the six months ended June 30, 2013 is as follows:

	Shares		Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term (In Years)
Options Outstanding at December 31, 2012	5,349,810		$	5.98	7.0
Granted	38,750		$	13.01
Exercised	(370,627	)	$	6.17
Canceled	(12,330	)	$	6.64
Options Outstanding at June 30, 2013	5,005,603		$	6.02	6.5
Options Vested and Expected to Vest at June 30, 2013	4,967,369		$	6.02	6.5
Options Exercisable at June 30, 2013	3,176,119		$	6.58	5.3
Shares Available for Grant under the 2008 Plan	3,313,661

The weighted average grant-date fair value of stock options granted during the six months ended June 30, 2013 was $8.31. Stock-based compensation expense for the three and six months ended June 30, 2013 and 2012 was recorded as follows:

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
	(In thousands)
Research and development	$	422	$	284	$	863	$	679
General and administrative	254		164		521		409
Total stock-based compensation expense	$	676	$	448	$	1,384	$	1,088

The fair values of employee and director stock options granted during the three and six months ended June 30, 2013 and 2012 were valued using the Black-Scholes option-pricing model with the following assumptions:

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
Expected stock price volatility	72	%	71	%	72	%	70 - 71	%
Expected option term	6.0 years		6.0 years		6.0 years		6.0 years
Risk-free interest rate	1.2 — 1.8	%	0.9 — 1.3	%	1.2 — 1.8	%	0.9 — 1.4	%
Expected dividend yield	None		None		None		None

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 50
-Section 50
-Paragraph 1
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-Name Staff Accounting Bulletin (SAB)
-Number Topic 14

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph 64, 65, A240
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Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Statement of Position (SOP)
-Number 93-6
-Paragraph 53
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Income Taxes	6 Months Ended
Income Taxes	Jun. 30, 2013
Income Taxes
Income Taxes	(12) Income Taxes Massachusetts, New Jersey and Connecticut are the three states in which the Company primarily operates or has operated and has income tax nexus. The Company is not currently under examination by any jurisdictions for any tax year. The Company has evaluated the positive and negative evidence bearing upon the realizability of its net deferred tax assets, which are comprised principally of net operating loss carryforwards, capitalized R&D expenditures and R&D tax credit carryforwards. The Company has determined that it is more likely than not that it will not recognize the benefits of federal and state deferred tax assets and, as a result, a full valuation allowance was maintained at June 30, 2013 and December 31, 2012 against the Company’s net deferred tax assets.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

+ Details

Commitments and Contingent Liabilities	6 Months Ended
Commitments and Contingent Liabilities	Jun. 30, 2013
Commitments and Contingent Liabilities
Commitments and Contingent Liabilities	(13) Commitments and Contingent Liabilities Except as set forth below, the significant commitments and contingencies at June 30, 2013 are consistent with those disclosed in Notes 13 and 15 to the consolidated financial statements in our Annual Report on Form 10-K for the year ended December 31, 2012. On May 1, 2013, the Company entered into a lease agreement (the “Lease”) with Crown Perryville, LLC., as Landlord, pursuant to which the Company will lease approximately 33,000 square feet of office space in Hampton, New Jersey for use as an office and laboratory. The Lease has a five-year, five-month term which will commence on the later of November 15, 2013 or the date on which the alterations are substantially complete and a Certificate of Occupancy is issued. The Company’s obligation to pay rent commences five months after the lease commencement date. The annual rent obligations increase from $0.4 million in the first year to $0.5 million in the fifth year. The Lease includes two renewal options of five years each.

- Definition

The entire disclosure for commitments and contingencies.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6449706&loc=d3e16207-108621

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-Name Accounting Standards Codification
-Topic 460
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.25)
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-Publisher FASB
-Name FASB Interpretation (FIN)
-Number 14
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-Name Statement of Financial Accounting Standard (FAS)
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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Significant Accounting Policies (Policies)	6 Months Ended
Significant Accounting Policies (Policies)	Jun. 30, 2013
Significant Accounting Policies
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the Financial Accounting Standards Board (“FASB”) or other standard setting bodies that are adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on the Company’s financial position or results of operations upon adoption. In January 2013, the Company adopted a new U.S. GAAP accounting standard which amended guidance applicable to annual impairment tests of indefinite-lived intangible assets. The amended guidance added an optional qualitative assessment for determining whether an indefinite-lived intangible asset is impaired. Prior to this guidance, companies were required to perform an annual impairment test that included a calculation of the fair value of the asset and a comparison of that fair value with its carrying value. If the carrying value exceeded the fair value, an impairment was recorded. The amended guidance allows a company the option to perform a qualitative assessment, considering both negative and positive evidence, regarding the potential impairment of the indefinite-lived intangible asset. If, based on the qualitative analysis, the company determines that it is more likely than not that the fair value of such an asset exceeds its carrying value, the company would be permitted to conclude that the indefinite-lived intangible asset was not impaired without a quantitative calculation of the fair value of the asset. Otherwise, the company would perform the quantitative calculation of the fair value and the comparison with the carrying value. The Company’s adoption of this new standard did not have a material effect on its operating results or financial position.

Net Loss Per Share (Tables)

6 Months Ended

Jun. 30, 2013

Net Loss Per Share

Schedule of potentially dilutive common shares that have not been included in the net loss per common share calculations because the effect would have been anti-dilutive

	Six months ended June 30,
	2013	2012

Stock options	5,005,603	4,304,897
Restricted stock	12,000	12,000
	5,017,603	4,316,897

Comprehensive Loss (Tables)

6 Months Ended

Jun. 30, 2013

Comprehensive Loss

Summary of changes in accumulated other comprehensive income (loss) by component

	Unrealized Gain (Loss) on Marketable Securities, net of tax			Foreign Currency Items			Total
	(In thousands)
Balance at March 31, 2013	$	102		$	2,587		$	2,689
Other comprehensive income (loss) before reclassifications	(140		)	(1		)	(141		)
Amounts reclassified from other comprehensive income	—			—			—
Net current-period other comprehensive income	(140		)	(1		)	(141		)
Balance at June 30, 2013	$	(38	)	$	2,586		$	2,548

Balance at December 31, 2012	$	156		$	2,589		$	2,745
Other comprehensive income (loss) before reclassifications	(194		)	(3		)	(197		)
Amounts reclassified from other comprehensive income	—			—			—
Net current-period other comprehensive income	(194		)	(3		)	(197		)
Balance at June 30, 2013	$	(38	)	$	2,586		$	2,548

Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Measurements

Schedule of financial assets subject to fair value measurements

	As of June 30, 2013		Level 1		Level 2		Level 3
	(In thousands)
Money market funds and cash equivalents	$	22,709	$	22,709	—		—
Marketable securities	$	129,083	—		$	129,083	—
	$	151,792	$	22,709	$	129,083	—

	As of December 31, 2012		Level 1		Level 2		Level 3
	(In thousands)
Money market funds and cash equivalents	$	18,688	$	18,688	—		—
Marketable securities	$	59,065	—		$	59,065	—
	$	77,753	$	18,688	$	59,065	—

- Definition

Tabular disclosure of assets, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, by class that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3).

+ References + Details

Marketable Securities (Tables)

6 Months Ended

Jun. 30, 2013

Marketable Securities

Summary of marketable securities

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
	(In thousands)
June 30, 2013
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	34,189	$	15	$	5	$	34,199
Maturing after one year through three years	34,030		61		22		34,069
Total U.S. government and municipal obligations	$	68,219	$	76	$	27	$	68,268
Corporate debt securities
Maturing in one year or less	$	33,336	$	10	$	32	$	33,314
Maturing after one year through three years	27,566		—		65		27,501
Total corporate debt securities	$	60,902	$	10	$	97	$	60,815
Total marketable securities	$	129,121	$	86	$	124	$	129,083

December 31, 2012
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	15,566	$	28	$	—	$	15,594
Maturing after one year through three years	19,797		99		1		19,895
Total U.S. government and municipal obligations	$	35,363	$	127	$	1	$	35,489
Corporate debt securities
Maturing in one year or less	$	17,353	$	23	$	4	$	17,372
Maturing after one year through three years	6,193		14		3		6,204
Total corporate debt securities	$	23,546	$	37	$	7	$	23,576
Total marketable securities	$	58,909	$	164	$	8	$	59,065

Intangible Assets and Goodwill (Tables)

6 Months Ended

Jun. 30, 2013

Intangible Assets and Goodwill

Schedule of intangible assets, net of accumulated amortization, and goodwill

		June 30, 2013							December 31, 2012
	Estimated Life	Cost		Accumulated Amortization			Net		Cost		Accumulated Amortization			Net
	(In thousands)
Intangible Assets:
IPR&D	Indefinite	$	11,800	—			$	11,800	$	11,800	—			$	11,800
Amgen Amendment	16 years	14,500		$	(3,363	)	11,137		14,500		$	(2,915	)	11,585
Core Technology	11 years	1,296		(907		)	389		1,296		(848		)	448
Total Intangible Assets		$	27,596	$	(4,270	)	$	23,326	$	27,596	$	(3,763	)	$	23,833
Goodwill	Indefinite	$	8,965	—			$	8,965	$	8,965	—			$	8,965

Other Long-Term Liabilities (Tables)

6 Months Ended

Jun. 30, 2013

Other Long-Term Liabilities

Schedule of Other long-term liabilities

	June 30, 2013			December 31, 2012
	(In thousands)
Deferred Rent	$	422		$	434
Net Deferred Tax Liability related to IPR&D	4,661			4,661
Deferred Income from Sale of Tax Benefits	1,630			1,118
Loan Payable	443			472
Other	10			39
Total	7,166			6,724
Less Current Portion	(530		)	(388		)
Long-Term Portion	$	6,636		$	6,336

Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2013

Stock-Based Compensation

Summary of stock option activity

	Shares		Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term (In Years)
Options Outstanding at December 31, 2012	5,349,810		$	5.98	7.0
Granted	38,750		$	13.01
Exercised	(370,627	)	$	6.17
Canceled	(12,330	)	$	6.64
Options Outstanding at June 30, 2013	5,005,603		$	6.02	6.5
Options Vested and Expected to Vest at June 30, 2013	4,967,369		$	6.02	6.5
Options Exercisable at June 30, 2013	3,176,119		$	6.58	5.3
Shares Available for Grant under the 2008 Plan	3,313,661

Schedule of stock-based compensation expense

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
	(In thousands)
Research and development	$	422	$	284	$	863	$	679
General and administrative	254		164		521		409
Total stock-based compensation expense	$	676	$	448	$	1,384	$	1,088

Schedule of assumptions used for the fair values of employee and director stock options granted

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
Expected stock price volatility	72	%	71	%	72	%	70 - 71	%
Expected option term	6.0 years		6.0 years		6.0 years		6.0 years
Risk-free interest rate	1.2 — 1.8	%	0.9 — 1.3	%	1.2 — 1.8	%	0.9 — 1.4	%
Expected dividend yield	None		None		None		None

- Definition

Tabular disclosure of the allocation of equity-based compensation costs to a given line item on the balance sheet and income statement for the period. This may include the reporting line for the costs and the amount capitalized and expensed.

+ References + Details

Basis of Presentation (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Basis of Presentation (Details) - USD ($) $ in Thousands	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Basis of Presentation
Cash, cash equivalents and marketable securities	$ 155,000		$ 155,000
Working capital	143,900		143,900
Net Loss	$ (19,016)	$ (13,773)	(36,348)	$ (27,289)
Net cash used in operations			$ (35,258)	$ (25,512)

Net Loss Per Share (Details) - shares	6 Months Ended
Net Loss Per Share (Details) - shares	Jun. 30, 2013	Jun. 30, 2012
Anti-dilutive securities
Potentially dilutive common shares that have not been included in the net loss per common share calculations because the effect would have been anti-dilutive	5,017,603	4,316,897
Stock options
Anti-dilutive securities
Potentially dilutive common shares that have not been included in the net loss per common share calculations because the effect would have been anti-dilutive	5,005,603	4,304,897
Restricted stock
Anti-dilutive securities
Potentially dilutive common shares that have not been included in the net loss per common share calculations because the effect would have been anti-dilutive	12,000	12,000

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Antidilution
-URI http://asc.fasb.org/extlink&oid=6505113

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Diluted Earnings Per Share
-URI http://asc.fasb.org/extlink&oid=6510752

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Contingent Stock Agreement
-URI http://asc.fasb.org/extlink&oid=6508534

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 40
-Subparagraph c
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 13, 14
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Emerging Issues Task Force (EITF)
-Number 07-4
-Paragraph 4
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 128
-Paragraph 171
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Comprehensive Loss (Details) - USD ($) $ in Thousands	Jun. 30, 2013	Jun. 30, 2013
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	$ 2,689	$ 2,745
Other comprehensive income (loss) before reclassifications	(141)	(197)
Net current-period other comprehensive income	(141)	(197)
Balance at the end of the period	2,548	2,548
Amounts reclassified from other comprehensive income	0	0
Unrealized Gain (Loss) on Marketable Securities, net of tax
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	102	156
Other comprehensive income (loss) before reclassifications	(140)	(194)
Net current-period other comprehensive income	(140)	(194)
Balance at the end of the period	(38)	(38)
Foreign Currency Items
Changes in accumulated other comprehensive income (loss) by component
Balance at the beginning of the period	2,587	2,589
Other comprehensive income (loss) before reclassifications	(1)	(3)
Net current-period other comprehensive income	(1)	(3)
Balance at the end of the period	$ 2,586	$ 2,586

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e681-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669686-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 31
-Article 5

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS115-1/124-1
-Paragraph 15D
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 12
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 130
-Paragraph 14, 17, 26
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

+ Details

Fair Value Measurements (Details) - USD ($) $ in Thousands	Jun. 30, 2013	Dec. 31, 2012
Fair value measurements
Assets transferred between the fair value measurement classifications	$ 0
Liabilities transferred between the fair value measurement classifications	0
Fair Value Measurements \| Fair value
Fair value measurements
Money market funds and cash equivalents	22,709	$ 18,688
Marketable securities	129,083	59,065
Total financial assets at fair value	151,792	77,753
Fair Value Measurements \| Level 1
Fair value measurements
Money market funds and cash equivalents	22,709	18,688
Total financial assets at fair value	22,709	18,688
Fair Value Measurements \| Level 2
Fair value measurements
Marketable securities	129,083	59,065
Total financial assets at fair value	$ 129,083	$ 59,065

Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2013	Dec. 31, 2012
Amortized Cost
Amortized cost	$ 129,121	$ 58,909
Gross Unrealized Gains
Gross Unrealized Gains	86	164
Gross Unrealized Losses
Gross Unrealized Losses	124	8
Fair Value
Fair Value	129,083	59,065
Marketable securities considered to be other-than-temporarily impaired	0
U.S. government and municipal obligations
Amortized Cost
Maturing in one year or less	34,189	15,566
Maturing after one year through three years	34,030	19,797
Amortized cost	68,219	35,363
Gross Unrealized Gains
Maturing in one year or less	15	28
Maturing after one year through three years	61	99
Gross Unrealized Gains	76	127
Gross Unrealized Losses
Maturing in one year or less	5
Maturing after one year through three years	22	1
Gross Unrealized Losses	27	1
Fair Value
Maturing in one year or less	34,199	15,594
Maturing after one year through three years	34,069	19,895
Fair Value	68,268	35,489
Corporate debt securities
Amortized Cost
Maturing in one year or less	33,336	17,353
Maturing after one year through three years	27,566	6,193
Amortized cost	60,902	23,546
Gross Unrealized Gains
Maturing in one year or less	10	23
Maturing after one year through three years		14
Gross Unrealized Gains	10	37
Gross Unrealized Losses
Maturing in one year or less	32	4
Maturing after one year through three years	65	3
Gross Unrealized Losses	97	7
Fair Value
Maturing in one year or less	33,314	17,372
Maturing after one year through three years	27,501	6,204
Fair Value	$ 60,815	$ 23,576

Intangible Assets and Goodwill (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Intangible Assets and Goodwill
Goodwill	$ 8,965	$ 8,965
Finite-lived intangible asset
Accumulated Amortization	(4,270)	(3,763)
Total Intangible Assets
Cost of total intangible assets	27,596	27,596
Intangible Assets, Net (Excluding Goodwill)	$ 23,326	23,833
Amgen Amendment
Finite-lived intangible asset
Estimated Life	16 years
Cost	$ 14,500	14,500
Accumulated Amortization	(3,363)	(2,915)
Net	$ 11,137	11,585
Core Technology
Finite-lived intangible asset
Estimated Life	11 years
Cost	$ 1,296	1,296
Accumulated Amortization	(907)	(848)
Net	389	448
IPR&D
Indefinite-lived intangible assets:
Indefinite-lived intangible assets	$ 11,800	$ 11,800

Term Loan (Details) - USD ($) $ in Millions	1 Months Ended			3 Months Ended		6 Months Ended
Term Loan (Details) - USD ($) $ in Millions	May 31, 2013	Mar. 31, 2011	Dec. 31, 2010	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
MidCap
Term Loan
Interest expense on the term loan				$ 0.5	$ 0.4	$ 0.8	$ 0.8
Term Loan
Term Loan
Amount owed under the term loan		$ 15.0
Repayment of principal amount	$ 8.8
Amount of interest, prepayment and final payment fees	$ 0.7
Term Loan \| MidCap
Term Loan
Amount borrowed			$ 10.0
Term Loan \| GECC
Term Loan
Amount borrowed		$ 5.0

Other Long-Term Liabilities (Details) - USD ($) $ in Thousands	1 Months Ended			6 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Other Long-Term Liabilities
Deferred Rent				$ 422		$ 434
Net Deferred Tax Liability related to IPR&D				4,661		4,661
Deferred Income from Sale of Tax Benefits				1,630		1,118
Loan Payable				443		472
Other				10		39
Total				7,166		6,724
Less Current Portion				(530)		(388)
Long-Term Portion				6,636		$ 6,336
Amount at which New Jersey tax benefit agreed to be sold	$ 800	$ 800	$ 600	$ 200	$ 100
Amount of sale of New Jersey tax benefit	$ 800	$ 700	$ 500
Period for which base of operations must be maintained				5 years

Stockholders' Equity (Details) - USD ($) $ in Thousands	1 Months Ended	6 Months Ended
Stockholders' Equity (Details) - USD ($) $ in Thousands	Sep. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jan. 31, 2011
Stockholders' Equity
Common stock issued (in shares)		80,977,696		64,359,513
Net proceeds from sale of common stock		$ 114,187	$ 51,957
Common stock in an underwritten public offering issued (in shares)		13,800,000	12,075,000
Shares issued on exercise of over-allotment option by underwriters (in shares)		1,800,000	1,575,000
Net proceeds from sale of stock in an underwritten public offering		$ 97,000	$ 43,400
Cantor Agreement
Stockholders' Equity
Common stock issued (in shares)			2,450,000
Common stock available for sale (in shares)					5,000,000
Net proceeds from sale of common stock			$ 8,500
Cantor Amendment
Stockholders' Equity
Common stock issued (in shares)		2,433,608
Net proceeds from sale of common stock		$ 17,100
Aggregate offering price of additional shares which the entity can issue as per amended agreement	$ 44,000	$ 4,400
Fixed commission rate (as a percent)	3.00%
Notice period for termination of agreement	10 days

Stock-Based Compensation (Details) - Stock options - $ / shares	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Shares
Options Outstanding at beginning of the period (in shares)	5,349,810
Granted (in shares)	38,750
Exercised (in shares)	(370,627)
Canceled (in shares)	(12,330)
Options Outstanding at the end of the period (in shares)	5,005,603	5,349,810
Options Vested and Expected to Vest at the end of the period (in shares)	4,967,369
Options Exercisable at the end of the period (in shares)	3,176,119
Shares Available for Grant under the 2008 Plan (in shares)	3,313,661
Weighted Average Exercise Price Per Share
Options Outstanding at beginning of the period (in dollars per share)	$ 5.98
Granted (in dollars per share)	13.01
Exercised (in dollars per share)	6.17
Canceled (in dollars per share)	6.64
Options Outstanding at the end of the period (in dollars per share)	6.02	$ 5.98
Options Vested and Expected to Vest at the end of the period (in dollars per share)	6.02
Options Exercisable at the end of the period (in dollars per share)	$ 6.58
Weighted Average Remaining Contractual Term
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	6 years 6 months	7 years
SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2	6 years 6 months	7 years
Options Vested and Expected to Vest at the end of the period	6 years 6 months
Options Exercisable at the end of the period	5 years 3 months 18 days
Additional information
Weighted average grant-date fair value (in dollars per share)	$ 8.31

Stock-Based Compensation (Details 2) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Valuation and Expenses Information
Total stock-based compensation expense (in dollars)	$ 676	$ 448	$ 1,384	$ 1,088
Stock options
Assumptions used for fair values of employee and director stock options granted
Expected stock price volatility (as a percent)	72.00%	71.00%	72.00%
Expected option term	6 years	6 years	6 years	6 years
Expected dividend yield (as a percent)	0.00%	0.00%	0.00%	0.00%
Stock options \| Minimum
Assumptions used for fair values of employee and director stock options granted
Expected stock price volatility (as a percent)				70.00%
Risk-free interest rate (as a percent)	1.20%	0.90%	1.20%	0.90%
Stock options \| Maximum
Assumptions used for fair values of employee and director stock options granted
Expected stock price volatility (as a percent)				71.00%
Risk-free interest rate (as a percent)	1.80%	1.30%	1.80%	1.40%
Research and development
Valuation and Expenses Information
Total stock-based compensation expense (in dollars)	$ 422	$ 284	$ 863	$ 679
General and administrative
Valuation and Expenses Information
Total stock-based compensation expense (in dollars)	$ 254	$ 164	$ 521	$ 409

Income Taxes (Details)	Jun. 30, 2013 item
Net operating loss and tax credit carryforwards
Number of states in which the entity primarily operates or has operated and has income tax nexus	3

Commitments and Contingent Liabilities (Details) $ in Millions	May 02, 2013 USD ($) ft² item
Lease
Area of office space (in square feet) \| ft²	33,000
Term of lease	5 years 5 months
Period from the lease commencement date after which the Company's obligation to pay rent commences	5 months
Annual rental obligations in the first year	$ 0.4
Annual rental obligations in the fifth year	$ 0.5
Number of renewal options \| item	2
Period of each renewal option	5 years