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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2016	Apr. 26, 2016
Document and Entity Information
Entity Registrant Name	Celldex Therapeutics, Inc.
Entity Central Index Key	0000744218
Document Type	10-Q
Document Period End Date	Mar. 31, 2016
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		98,718,516
Document Fiscal Year Focus	2016
Document Fiscal Period Focus	Q1

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Current Assets:
Cash and Cash Equivalents	$ 63,025	$ 72,108
Marketable Securities	190,992	217,781
Accounts and Other Receivables	847	970
Prepaid and Other Current Assets	6,091	4,077
Total Current Assets	260,955	294,936
Property and Equipment, Net	11,392	11,461
Intangible Assets, Net	20,541	20,794
Other Assets	78	1,428
Goodwill	8,965	8,965
Total Assets	301,931	337,584
Current Liabilities:
Accounts Payable	2,637	1,506
Accrued Expenses	18,431	24,316
Current Portion of Long-Term Liabilities	4,239	4,418
Total Current Liabilities	25,307	30,240
Other Long-Term Liabilities	16,592	17,239
Total Liabilities	41,899	47,479
Commitments and Contingent Liabilities
Stockholders' Equity:
Convertible Preferred Stock, $.01 Par Value; 3,000,000 Shares Authorized; No Shares Issued and Outstanding at March 31, 2016 and December 31, 2015
Common Stock, $.001 Par Value; 297,000,000 Shares Authorized; 98,718,484 and 98,685,595 Shares Issued and Outstanding at March 31, 2016 and December 31, 2015, respectively	99	99
Additional Paid-In Capital	882,875	878,655
Accumulated Other Comprehensive Income	2,687	2,307
Accumulated Deficit	(625,629)	(590,956)
Total Stockholders' Equity	260,032	290,105
Total Liabilities and Stockholders' Equity	$ 301,931	$ 337,584

CONDENSED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2016	Dec. 31, 2015
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	98,718,484	98,685,595
Common Stock, Shares Outstanding	98,718,484	98,685,595

CONDENSED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
REVENUE:
Product Development and Licensing Agreements	$ 453	$ 342
Contracts and Grants	850	144
Total Revenue	1,303	486
OPERATING EXPENSE:
Research and Development	27,447	25,125
General and Administrative	9,307	6,089
Amortization of Acquired Intangible Assets	253	253
Total Operating Expense	37,007	31,467
Operating Loss	(35,704)	(30,981)
Investment and Other Income, Net	1,031	807
Net Loss	$ (34,673)	$ (30,174)
Basic and Diluted Net Loss Per Common Share (in dollars per share)	$ (0.35)	$ (0.33)
Shares Used in Calculating Basic and Diluted Net Loss per Share (in shares)	98,689	92,437
COMPREHENSIVE LOSS:
Net Loss	$ (34,673)	$ (30,174)
Other Comprehensive Income:
Foreign Currency Translation Adjustments		15
Unrealized Gain on Marketable Securities	380	11
Comprehensive Loss	$ (34,293)	$ (30,148)

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	Mar. 31, 2016	Mar. 31, 2015
Cash Flows from Operating Activities:
Net Loss	$ (34,673)	$ (30,174)
Adjustments to Reconcile Net Loss to Net Cash Used in Operating Activities:
Depreciation and Amortization	742	672
Amortization of Intangible Assets	253	253
Amortization and Premium of Marketable Securities, Net	529	(1,219)
Loss on Sale or Disposal of Assets	70
Stock-Based Compensation Expense	3,940	2,281
Non-Cash Expense	1,638	72
Changes in Operating Assets and Liabilities:
Accounts and Other Receivables	123	(252)
Prepaid and Other Current Assets	(1,741)	(38)
Other Assets		(166)
Accounts Payable and Accrued Expenses	(4,957)	(3,220)
Other Liabilities	(826)	(798)
Net Cash Used in Operating Activities	(34,902)	(32,589)
Cash Flows from Investing Activities:
Sales and Maturities of Marketable Securities	74,939	57,067
Purchases of Marketable Securities	(48,860)	(120,541)
Acquisition of Property and Equipment	(540)	(1,561)
Net Cash Provided by (Used in) Investing Activities	25,539	(65,035)
Cash Flows from Financing Activities:
Net Proceeds from Stock Issuances		188,774
Proceeds from Issuance of Stock from Employee Benefit Plans	280	2,985
Net Cash Provided by Financing Activities	280	191,759
Effect of Exchange Rate Changes on Cash and Cash Equivalents		15
Net (Decrease) Increase in Cash and Cash Equivalents	(9,083)	94,150
Cash and Cash Equivalents at Beginning of Period	72,108	28,020
Cash and Cash Equivalents at End of Period	63,025	122,170
Non-cash Investing Activities
Acquisition of Property and Equipment included in Accounts Payable and Accrued Expenses	$ 278	$ 839

BASIS OF PRESENTATION	3 Months Ended
BASIS OF PRESENTATION	Mar. 31, 2016
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 balances and 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, 2015, which are included in the Company’s Annual Report on Form 10-K/A filed with the Securities and Exchange Commission (“SEC”) on February 25, 2016. 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 condensed 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, 2016. At March 31, 2016, the Company had cash, cash equivalents and marketable securities of $254.0 million. The Company incurred a net loss of $34.7 million for the three months ended March 31, 2016. Net cash used in operations for the three months ended March 31, 2016 was $34.9 million. The Company believes that the cash, cash equivalents and marketable securities at March 31, 2016 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 may 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	3 Months Ended
SIGNIFICANT ACCOUNTING POLICIES	Mar. 31, 2016
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 three months ended March 31, 2016 are consistent with those discussed in Note 2 to the financial statements in our Annual Report on Form 10-K/A for the year ended December 31, 2015, except for the adoption of new accounting standards during the first three months of 2016 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 February 2016, the FASB issued a new U.S. GAAP accounting standard which requires that all lessees recognize the assets and liabilities that arise from leases on the balance sheet and disclose qualitative and quantitative information about its leasing arrangements. The new standard will be effective for the Company on January 1, 2019. The Company is currently evaluating the potential impact that this standard may have on the Company’s financial statements. In March 2016, the FASB issued a new U.S. GAAP accounting standard which involves several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. The new standard will be effective for the Company on January 1, 2017. The Company is currently evaluating the potential impact that this standard may have on the Company’s financial statements.

NET LOSS PER SHARE

3 Months Ended

Mar. 31, 2016

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:

	As of March 31,
	2016	2015

Stock options	8,157,550	6,538,920
Restricted stock	9,750	4,000

	8,167,300	6,542,920

COMPREHENSIVE LOSS

3 Months Ended

Mar. 31, 2016

COMPREHENSIVE LOSS

COMPREHENSIVE LOSS

(4) Comprehensive Loss

The changes in accumulated other comprehensive income by component for the three months ended March 31, 2016 and 2015 are summarized below. No amounts were reclassified out of accumulated other comprehensive income during the three months ended March 31, 2016 and 2015.

	Unrealized Gain (Loss) on Marketable Securities, net of tax			Foreign Currency Items		Total
	(In thousands )
Balance at December 31, 2015	$	(289	)	$	2,596	$	2,307
Other comprehensive income before reclassifications	380			—		380

Net current-period other comprehensive income	380			—		380

Balance at March 31, 2016	$	91		$	2,596	$	2,687


Balance at December 31, 2014	$	9		$	2,581	$	2,590
Other comprehensive income before reclassifications	11			15		26

Net current-period other comprehensive income	11			15		26

Balance at March 31, 2015	$	20		$	2,596	$	2,616

- 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.

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+ Details

FAIR VALUE MEASUREMENTS

3 Months Ended

Mar. 31, 2016

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 March 31, 2016		Level 1		Level 2		Level 3
	(In thousands )
Money market funds and cash equivalents	$	57,369	$	—	$	57,369	$	—
Marketable securities	190,992		—		190,992		—

	$	248,361	$	—	$	248,361	$	—

	As of December 31, 2015		Level 1		Level 2		Level 3
	(In thousands )
Money market funds and cash equivalents	$	59,831	$	—	$	59,831	$	—
Marketable securities	217,781		—		217,781		—

	$	277,612	$	—	$	277,612	$	—

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 and accounts payable. 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.

+ References + Details

MARKETABLE SECURITIES

3 Months Ended

Mar. 31, 2016

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 )
March 31, 2016
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	70,124	$	32	$	(3	)	$	70,153
Maturing after one year through three years	5,396		31		—			5,427


Total U.S. government and municipal obligations	$	75,520	$	63	$	(3	)	$	75,580


Corporate debt securities
Maturing in one year or less	$	97,686	$	23	$	(18	)	$	97,691
Maturing after one year through three years	17,695		31		(5		)	17,721


Total corporate debt securities	$	115,381	$	54	$	(23	)	$	115,412


Total marketable securities	$	190,901	$	117	$	(26	)	$	190,992



December 31, 2015
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	48,871	$	4	$	(20	)	$	48,855
Maturing after one year through three years	15,940		24		(57		)	15,907


Total U.S. government and municipal obligations	$	64,811	$	28	$	(77	)	$	64,762


Corporate debt securities
Maturing in one year or less	$	129,327	$	2	$	(141	)	$	129,188
Maturing after one year through three years	23,932		1		(102		)	23,831


Total corporate debt securities	$	153,259	$	3	$	(243	)	$	153,019


Total marketable securities	$	218,070	$	31	$	(320	)	$	217,781

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 March 31, 2016. Marketable securities include $0.9 million and $1.5 million in accrued interest at March 31, 2016 and December 31, 2015, respectively.

- Definition

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

+ References + Details

INTANGIBLE ASSETS AND GOODWILL

3 Months Ended

Mar. 31, 2016

INTANGIBLE ASSETS AND GOODWILL

INTANGIBLE ASSETS AND GOODWILL

(7) Intangible Assets and Goodwill

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

		March 31, 2016							December 31, 2015
	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		(5,828		)	8,672		14,500		(5,605		)	8,895
Core Technology	11 years	1,296		(1,227		)	69		1,296		(1,197		)	99

Total Intangible Assets		$	27,596	$	(7,055	)	$	20,541	$	27,596	$	(6,802	)	$	20,794

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 glembatumumab vedotin. At the date of acquisition and at March 31, 2016, glembatumumab vedotin had not yet reached technological feasibility nor did it have any alternative future use. Glembatumumab vedotin is in a randomized, Phase 2b study for the treatment of triple negative breast cancer and a Phase 2 study for the treatment of metastatic melanoma.

The Company performed an impairment test of the goodwill asset as of March 31, 2016 and concluded that goodwill was not impaired.

- 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

OTHER LONG-TERM LIABILITIES

3 Months Ended

Mar. 31, 2016

OTHER LONG-TERM LIABILITIES

OTHER LONG-TERM LIABILITIES

(8) Other Long-Term Liabilities

Other long-term liabilities include the following:

	March 31, 2016			December 31, 2015
	(In thousands)
Deferred Rent	$	417		$	409
Net Deferred Tax Liability related to IPR&D	4,661			4,661
Deferred Income from Sale of Tax Benefits	11,620			12,219
Deferred Revenue	4,133			4,368

Total	20,831			21,657
Less Current Portion	(4,239		)	(4,418		)

Long-Term Portion	$	16,592		$	17,239

In November 2015, December 2014, January 2014, January 2013 and January 2012, the Company received approval from the New Jersey Economic Development Authority and agreed to sell New Jersey tax benefits of $9.8 million, $1.9 million, $1.1 million, $0.8 million and $0.8 million to an independent third party for $9.2 million, $1.8 million, $1.0 million, $0.8 million and $0.7 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 three months ended March 31, 2016 and 2015, the Company recorded $0.6 million to other income related to the sale of these tax benefits.

STOCKHOLDERS' EQUITY	3 Months Ended
STOCKHOLDERS' EQUITY	Mar. 31, 2016
STOCKHOLDERS' EQUITY
STOCKHOLDERS' EQUITY	(9) Stockholders’ Equity During the three months ended March 31, 2015, the Company issued 8,337,500 shares of its common stock in an underwritten public offering resulting in net proceeds to the Company of $188.8 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, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

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-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 30
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6405834&loc=d3e23285-112656

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21475-112644

Reference 11: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Preferred Stock
-URI http://asc.fasb.org/extlink&oid=6521494

Reference 12: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 13: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21564-112644

Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section E

Reference 15: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 4
-Section C

+ Details

STOCK-BASED COMPENSATION

3 Months Ended

Mar. 31, 2016

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION

(10) Stock-Based Compensation

A summary of stock option activity for the three months ended March 31, 2016 is as follows:

	Shares		Weighted Average Exercise Price Per Share		Weighted Average Remaining Contractual Term (In Years)
Options Outstanding at December 31, 2015	8,110,239		$	13.13	6.7
Granted	116,050		$	7.50
Exercised	(15,000	)	$	2.80
Canceled	(53,739	)	$	17.28

Options Outstanding at March 31, 2016	8,157,550		$	13.04	6.5

Options Vested and Expected to Vest at March 31, 2016	8,110,040		$	13.00	6.5
Options Exercisable at March 31, 2016	4,948,179		$	8.82	5.2
Shares Available for Grant under the 2008 Plan	5,727,572

The weighted average grant-date fair value of stock options granted during the three months ended March 31, 2016 was $4.71. Stock-based compensation expense for the three months ended March 31, 2016 and 2015 was recorded as follows:

	Three months ended March 31,
	2016		2015
	(In thousands)
Research and development	$	1,815	$	1,269
General and administrative	2,125		1,012

Total stock-based compensation expense	$	3,940	$	2,281

The fair values of employee stock options granted during the three months ended March 31, 2016 and 2015 were valued using the Black-Scholes option-pricing model with the following assumptions:

	Three months ended March 31,
	2016		2015
Expected stock price volatility	70	%	69	%
Expected option term	6.0 Years		6.0 Years
Risk-free interest rate	1.6	%	1.8	%
Expected dividend yield	None		None

REVENUE	3 Months Ended
REVENUE	Mar. 31, 2016
REVENUE.
REVENUE	(11) Revenue Bristol-Myers Squibb Company (BMS) In May 2014, the Company entered into a clinical trial collaboration with BMS to evaluate the safety, tolerability and preliminary efficacy of varlilumab and Opdivo®, BMS’s PD-1 immune checkpoint inhibitor, in a Phase 1/2 study. Under the terms of this clinical trial collaboration, BMS made a one-time payment to the Company of $5.0 million and BMS and the Company amended the terms of the Company’s existing license agreement with Medarex (a subsidiary of BMS) related to the Company’s CD27 program whereby certain future milestone payments were waived and future royalty rates were reduced that may have been due from the Company to Medarex. In return, BMS was granted a time-limited right of first negotiation if the Company wishes to out-license varlilumab. The companies also agreed to work exclusively with each other to explore anti-PD-1 antagonist antibody and anti-CD27 agonist antibody combination regimens. The clinical trial collaboration provides that the companies will share development costs and that the Company will be responsible for conducting the ongoing Phase 1/2 study. The Company has determined that its performance obligations under the BMS agreement, which primarily include performing research and development, supplying varlilumab and participating in the joint development committee, should be accounted for as a single unit of accounting and estimated that its performance period under the BMS agreement would be 5 years. Accordingly, the $5.0 million up-front payment was initially recorded as deferred revenue and is being recognized as revenue on a straight-line basis over the estimated 5-year performance period using the Contingency Adjusted Performance Model (CAPM). The BMS agreement also provides for BMS to reimburse the Company for 50% of the external costs incurred by the Company in connection with the clinical trial. These BMS payments will be recognized as revenue under the CAPM. The Company recorded $0.4 million and $0.3 million in revenue related to the BMS agreement during the three months ended March 31, 2016 and 2015, respectively. Rockefeller University (Rockefeller) In September 2013, the Company entered into an agreement, as amended, with Rockefeller pursuant to which the Company will performs research and development services for Rockefeller. The Company bills Rockefeller quarterly for actual time and direct costs incurred and records those amounts to revenue in the quarter the services are performed. The Company recorded $0.4 million and $0.1 million in revenue related to the Rockefeller agreement during the three months ended March 31, 2016 and 2015, respectively.

INCOME TAXES	3 Months Ended
INCOME TAXES	Mar. 31, 2016
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 March 31, 2016 and December 31, 2015 against the Company’s net deferred tax assets.

SUBSEQUENT EVENT	3 Months Ended
SUBSEQUENT EVENT	Mar. 31, 2016
SUBSEQUENT EVENT
SUBSEQUENT EVENT	(13) Subsequent Event In April 2016, the Company entered into a research and collaboration agreement with an undisclosed private company to access novel technologies and paid $3.5 million to support research activities and make an investment in the private company.

SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
SIGNIFICANT ACCOUNTING POLICIES (Policies)	Mar. 31, 2016
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 February 2016, the FASB issued a new U.S. GAAP accounting standard which requires that all lessees recognize the assets and liabilities that arise from leases on the balance sheet and disclose qualitative and quantitative information about its leasing arrangements. The new standard will be effective for the Company on January 1, 2019. The Company is currently evaluating the potential impact that this standard may have on the Company’s financial statements. In March 2016, the FASB issued a new U.S. GAAP accounting standard which involves several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. The new standard will be effective for the Company on January 1, 2017. The Company is currently evaluating the potential impact that this standard may have on the Company’s financial statements.

NET LOSS PER SHARE (Tables)

3 Months Ended

Mar. 31, 2016

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

	As of March 31,
	2016	2015

Stock options	8,157,550	6,538,920
Restricted stock	9,750	4,000

	8,167,300	6,542,920

COMPREHENSIVE LOSS (Tables)

3 Months Ended

Mar. 31, 2016

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 December 31, 2015	$	(289	)	$	2,596	$	2,307
Other comprehensive income before reclassifications	380			—		380

Net current-period other comprehensive income	380			—		380

Balance at March 31, 2016	$	91		$	2,596	$	2,687


Balance at December 31, 2014	$	9		$	2,581	$	2,590
Other comprehensive income before reclassifications	11			15		26

Net current-period other comprehensive income	11			15		26

Balance at March 31, 2015	$	20		$	2,596	$	2,616

FAIR VALUE MEASUREMENTS (Tables)

3 Months Ended

Mar. 31, 2016

FAIR VALUE MEASUREMENTS.

Schedule of financial assets subject to fair value measurements

	As of March 31, 2016		Level 1		Level 2		Level 3
	(In thousands )
Money market funds and cash equivalents	$	57,369	$	—	$	57,369	$	—
Marketable securities	190,992		—		190,992		—

	$	248,361	$	—	$	248,361	$	—

	As of December 31, 2015		Level 1		Level 2		Level 3
	(In thousands )
Money market funds and cash equivalents	$	59,831	$	—	$	59,831	$	—
Marketable securities	217,781		—		217,781		—

	$	277,612	$	—	$	277,612	$	—

MARKETABLE SECURITIES (Tables)

3 Months Ended

Mar. 31, 2016

MARKETABLE SECURITIES

Summary of marketable securities

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
	(In thousands )
March 31, 2016
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	70,124	$	32	$	(3	)	$	70,153
Maturing after one year through three years	5,396		31		—			5,427


Total U.S. government and municipal obligations	$	75,520	$	63	$	(3	)	$	75,580


Corporate debt securities
Maturing in one year or less	$	97,686	$	23	$	(18	)	$	97,691
Maturing after one year through three years	17,695		31		(5		)	17,721


Total corporate debt securities	$	115,381	$	54	$	(23	)	$	115,412


Total marketable securities	$	190,901	$	117	$	(26	)	$	190,992



December 31, 2015
Marketable securities
U.S. government and municipal obligations
Maturing in one year or less	$	48,871	$	4	$	(20	)	$	48,855
Maturing after one year through three years	15,940		24		(57		)	15,907


Total U.S. government and municipal obligations	$	64,811	$	28	$	(77	)	$	64,762


Corporate debt securities
Maturing in one year or less	$	129,327	$	2	$	(141	)	$	129,188
Maturing after one year through three years	23,932		1		(102		)	23,831


Total corporate debt securities	$	153,259	$	3	$	(243	)	$	153,019


Total marketable securities	$	218,070	$	31	$	(320	)	$	217,781

INTANGIBLE ASSETS AND GOODWILL (Tables)

3 Months Ended

Mar. 31, 2016

INTANGIBLE ASSETS AND GOODWILL

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

		March 31, 2016							December 31, 2015
	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		(5,828		)	8,672		14,500		(5,605		)	8,895
Core Technology	11 years	1,296		(1,227		)	69		1,296		(1,197		)	99

Total Intangible Assets		$	27,596	$	(7,055	)	$	20,541	$	27,596	$	(6,802	)	$	20,794

Goodwill	Indefinite	$	8,965	$	—		$	8,965	$	8,965	$	—		$	8,965

OTHER LONG-TERM LIABILITIES (Tables)

3 Months Ended

Mar. 31, 2016

OTHER LONG-TERM LIABILITIES

Schedule of other long-term liabilities

	March 31, 2016			December 31, 2015
	(In thousands)
Deferred Rent	$	417		$	409
Net Deferred Tax Liability related to IPR&D	4,661			4,661
Deferred Income from Sale of Tax Benefits	11,620			12,219
Deferred Revenue	4,133			4,368

Total	20,831			21,657
Less Current Portion	(4,239		)	(4,418		)

Long-Term Portion	$	16,592		$	17,239

STOCK-BASED COMPENSATION (Tables)

3 Months Ended

Mar. 31, 2016

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, 2015	8,110,239		$	13.13	6.7
Granted	116,050		$	7.50
Exercised	(15,000	)	$	2.80
Canceled	(53,739	)	$	17.28

Options Outstanding at March 31, 2016	8,157,550		$	13.04	6.5

Options Vested and Expected to Vest at March 31, 2016	8,110,040		$	13.00	6.5
Options Exercisable at March 31, 2016	4,948,179		$	8.82	5.2
Shares Available for Grant under the 2008 Plan	5,727,572

Schedule of stock-based compensation expense

	Three months ended March 31,
	2016		2015
	(In thousands)
Research and development	$	1,815	$	1,269
General and administrative	2,125		1,012

Total stock-based compensation expense	$	3,940	$	2,281

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

	Three months ended March 31,
	2016		2015
Expected stock price volatility	70	%	69	%
Expected option term	6.0 Years		6.0 Years
Risk-free interest rate	1.6	%	1.8	%
Expected dividend yield	None		None

BASIS OF PRESENTATION (Details) - USD ($) $ in Thousands	3 Months Ended
BASIS OF PRESENTATION (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Mar. 31, 2015
Basis of Presentation
Cash, cash equivalents and marketable securities	$ 254,000
Net Loss	(34,673)	$ (30,174)
Net cash used in operations	$ (34,902)	$ (32,589)

NET LOSS PER SHARE (Details) - shares	3 Months Ended
NET LOSS PER SHARE (Details) - shares	Mar. 31, 2016	Mar. 31, 2015
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	8,167,300	6,542,920
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	8,157,550	6,538,920
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	9,750	4,000

COMPREHENSIVE LOSS (Details) - USD ($) $ in Thousands	3 Months Ended
COMPREHENSIVE LOSS (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Mar. 31, 2015
Changes in accumulated other comprehensive income (loss) by component
Balance	$ 290,105
Balance	260,032
Unrealized Gain (Loss) on Marketable Securities
Changes in accumulated other comprehensive income (loss) by component
Balance	(289)	$ 9
Other comprehensive income before reclassifications	380	11
Net current-period other comprehensive income	380	11
Balance	91	20
Foreign Currency Items
Changes in accumulated other comprehensive income (loss) by component
Balance	2,596	2,581
Other comprehensive income before reclassifications		15
Net current-period other comprehensive income		15
Balance	2,596	2,596
Accumulated Other Comprehensive Income
Changes in accumulated other comprehensive income (loss) by component
Balance	2,307	2,590
Other comprehensive income before reclassifications	380	26
Amounts reclassified out of accumulated other comprehensive income	0	0
Net current-period other comprehensive income	380	26
Balance	$ 2,687	$ 2,616

FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Fair value measurements
Assets transferred between the fair value measurement classifications	$ 0
Liabilities transferred between the fair value measurement classifications	0
Fair Value Measurements \| Level 2
Fair value measurements
Money market funds and cash equivalents	57,369	$ 59,831
Marketable securities	190,992	217,781
Total financial assets at fair value	248,361	277,612
Fair Value Measurements \| Fair value
Fair value measurements
Money market funds and cash equivalents	57,369	59,831
Marketable securities	190,992	217,781
Total financial assets at fair value	$ 248,361	$ 277,612

MARKETABLE SECURITIES (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Amortized Cost
Amortized cost	$ 190,901	$ 218,070
Gross Unrealized Gains
Gross Unrealized Gains	117	31
Gross Unrealized Losses
Gross Unrealized Losses	(26)	(320)
Fair Value
Fair Value	190,992	217,781
Marketable securities considered to be other-than-temporarily impaired	0
Accrued interest included in marketable securities	900	1,500
U.S. government and municipal obligations
Amortized Cost
Maturing in one year or less	70,124	48,871
Maturing after one year through three years	5,396	15,940
Amortized cost	75,520	64,811
Gross Unrealized Gains
Maturing in one year or less	32	4
Maturing after one year through three years	31	24
Gross Unrealized Gains	63	28
Gross Unrealized Losses
Maturing in one year or less	(3)	(20)
Maturing after one year through three years		(57)
Gross Unrealized Losses	(3)	(77)
Fair Value
Maturing in one year or less	70,153	48,855
Maturing after one year through three years	5,427	15,907
Fair Value	75,580	64,762
Corporate debt securities
Amortized Cost
Maturing in one year or less	97,686	129,327
Maturing after one year through three years	17,695	23,932
Amortized cost	115,381	153,259
Gross Unrealized Gains
Maturing in one year or less	23	2
Maturing after one year through three years	31	1
Gross Unrealized Gains	54	3
Gross Unrealized Losses
Maturing in one year or less	(18)	(141)
Maturing after one year through three years	(5)	(102)
Gross Unrealized Losses	(23)	(243)
Fair Value
Maturing in one year or less	97,691	129,188
Maturing after one year through three years	17,721	23,831
Fair Value	$ 115,412	$ 153,019

INTANGIBLE ASSETS AND GOODWILL (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Intangible Assets and Goodwill
Goodwill	$ 8,965	$ 8,965
Finite-lived intangible asset
Accumulated Amortization	(7,055)	(6,802)
Total Intangible Assets
Cost of total intangible assets	27,596	27,596
Intangible Assets, Net (Excluding Goodwill)	$ 20,541	20,794
Amgen Amendment
Finite-lived intangible asset
Estimated Life	16 years
Cost	$ 14,500	14,500
Accumulated Amortization	(5,828)	(5,605)
Net	$ 8,672	8,895
Core Technology
Finite-lived intangible asset
Estimated Life	11 years
Cost	$ 1,296	1,296
Accumulated Amortization	(1,227)	(1,197)
Net	69	99
IPR&D
Indefinite-lived intangible assets:
Indefinite-lived intangible assets	$ 11,800	$ 11,800

OTHER LONG-TERM LIABILITIES (Details) - USD ($) $ in Thousands	1 Months Ended					3 Months Ended
	Nov. 30, 2015	Dec. 31, 2014	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
OTHER LONG-TERM LIABILITIES
Deferred Rent						$ 417		$ 409
Net Deferred Tax Liability related to IPR&D						4,661		4,661
Deferred Income from Sale of Tax Benefits						11,620		12,219
Deferred Revenue						4,133		4,368
Total						20,831		21,657
Less Current Portion						(4,239)		(4,418)
Long-Term Portion						$ 16,592		$ 17,239
Amount at which New Jersey tax benefit agreed to be sold	$ 9,800	$ 1,900	$ 1,100	$ 800	$ 800
Amount of sale of New Jersey tax benefit	$ 9,200	$ 1,800	$ 1,000	$ 800	$ 700
Period for which base of operations must be maintained						5 years
Other income related to sale of tax benefits						$ 600	$ 600

STOCKHOLDERS' EQUITY (Details) - Underwritten Public Offering $ in Millions	3 Months Ended
	Mar. 31, 2015 USD ($) shares
Stockholders' Equity
Common stock issued (in shares) \| shares	8,337,500
Net proceeds from sale of stock in an underwritten public offering \| $	$ 188.8

STOCK-BASED COMPENSATION - SUMMARY OF PLANS (Details) - Stock options - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Shares
Options Outstanding at beginning of the period (in shares)	8,110,239
Granted (in shares)	116,050
Exercised (in shares)	(15,000)
Canceled (in shares)	(53,739)
Options Outstanding at the end of the period (in shares)	8,157,550	8,110,239
Options Vested and Expected to Vest at the end of the period (in shares)	8,110,040
Options Exercisable at the end of the period (in shares)	4,948,179
Shares Available for Grant under the 2008 Plan (in shares)	5,727,572
Weighted Average Exercise Price Per Share
Options Outstanding at beginning of the period (in dollars per share)	$ 13.13
Granted (in dollars per share)	7.50
Exercised (in dollars per share)	2.80
Canceled (in dollars per share)	17.28
Options Outstanding at the end of the period (in dollars per share)	13.04	$ 13.13
Options Vested and Expected to Vest at the end of the period (in dollars per share)	13.00
Options Exercisable at the end of the period (in dollars per share)	$ 8.82
Weighted Average Remaining Contractual Term
Options Outstanding at the beginning of the period	6 years 6 months	6 years 8 months 12 days
Options Outstanding at the end of the period	6 years 6 months	6 years 8 months 12 days
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 2 months 12 days
Additional information
Weighted average grant-date fair value (in dollars per share)	$ 4.71

STOCK-BASED COMPENSATION - VALUATION AND EXPENSES INFORMATION (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Valuation and Expenses Information
Total stock-based compensation expense (in dollars)	$ 3,940	$ 2,281
Stock options
Assumptions used for fair values of employee and director stock options granted
Expected stock price volatility (as a percent)	70.00%	69.00%
Expected option term	6 years	6 years
Risk-free interest rate (as a percent)	1.60%	1.80%
Expected dividend yield (as a percent)	0.00%	0.00%
Research and development
Valuation and Expenses Information
Total stock-based compensation expense (in dollars)	$ 1,815	$ 1,269
General and administrative
Valuation and Expenses Information
Total stock-based compensation expense (in dollars)	$ 2,125	$ 1,012

REVENUE (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
REVENUE (Details) - USD ($) $ in Thousands	May 31, 2014	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
REVENUE
Deferred Revenue		$ 4,133		$ 4,368
Product development and licensing agreements revenue		453	$ 342
Contracts and grants revenue		850	144
BMS \| PD-1 Immune Checkpoint Inhibitor
REVENUE
Term of the agreement	5 years
Deferred Revenue	$ 5,000
Reimbursement of external costs incurred by the company (as a percent)	50.00%
Product development and licensing agreements revenue		400	300
Rockefeller
REVENUE
Contracts and grants revenue		$ 400	$ 100

INCOME TAXES (Details)	Mar. 31, 2016 item
INCOME TAXES
Number of states in which the entity primarily operates or has operated and has income tax nexus	3

SUBSEQUENT EVENT (Details) $ in Millions	1 Months Ended
SUBSEQUENT EVENT (Details) $ in Millions	Apr. 30, 2016 USD ($)
Subsequent Event
Subsequent Event
Payment for research and collaboration agreement and investment in company	$ 3.5