Arqule (ARQL) 10-K 29 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Feb. 17, 2016	Jun. 30, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	ARQULE INC
Entity Central Index Key	1,019,695
Trading Symbol	arql
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Well-Known Seasoned Issuer	No
Entity Common Stock, Shares Outstanding		62,929,706
Entity Public Float			$ 100,514,960
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Amendment Flag	false
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY

BALANCE SHEETS

BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 13,983	$ 12,525
Marketable securities-short term	24,789	46,683
Prepaid expenses and other current assets	714	1,893
Total current assets	39,486	61,101
Marketable securities-long term		2,058
Property and equipment, net	266	133
Other assets	252	102
Total assets	40,004	63,394
Current liabilities:
Accounts payable and accrued expenses	6,234	6,947
Current portion of deferred revenue	4,591	11,098
Current portion of deferred gain on sale leaseback		232
Total current liabilities	10,825	18,277
Deferred revenue, net of current portion		4,572
Total liabilities	$ 10,825	$ 22,849
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred stock, $0.01 par value; 1,000,000 shares authorized; no shares issued or outstanding
Common stock, $0.01 par value; 100,000,000 shares authorized; 62,939,780 and 62,821,781 shares issued and outstanding at December 31, 2015 and 2014, respectively	$ 629	$ 628
Additional paid-in capital	510,664	508,270
Accumulated other comprehensive income (loss)	3	(10)
Accumulated deficit	(482,117)	(468,343)
Total stockholders' equity	29,179	40,545
Total liabilities and stockholders' equity	$ 40,004	$ 63,394

BALANCE SHEETS (Parentheticals)

BALANCE SHEETS (Parentheticals) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Statement Of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	62,939,780	62,821,781
Common stock, shares outstanding	62,939,780	62,821,781

STATEMENTS OF OPERATIONS AND CO

STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue:
Research and development revenue	$ 11,239	$ 11,254	$ 15,914
Costs and expenses:
Research and development	15,561	22,271	27,555
General and administrative	9,830	12,154	12,836
Restructuring and other costs		1,099	650
Total costs and expenses	25,391	35,524	41,041
Loss from operations	(14,152)	(24,270)	(25,127)
Interest income	101	272	502
Interest expense		(35)	(32)
Other income	277	642	57
Loss before income taxes	$ (13,774)	$ (23,391)	$ (24,600)
Provision for income taxes
Net loss	$ (13,774)	$ (23,391)	$ (24,600)
Unrealized gain (loss) on marketable securities	13	(77)	(35)
Comprehensive loss	$ (13,761)	$ (23,468)	$ (24,635)
Basic and diluted net loss per share:
Net loss per share (in dollars per share)	$ (0.22)	$ (0.37)	$ (0.39)
Weighted average basic and diluted common shares outstanding (in shares)	62,808	62,627	62,480

STATEMENTS OF STOCKHOLDERS' EQU

STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS)	ACCUMULATED DEFICIT	Total
Balance at Dec. 31, 2012	$ 624	$ 500,655	$ 102	$ (420,352)	$ 81,029
Balance (in shares) at Dec. 31, 2012	62,399,827
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises and issuance of stock	$ 2	72			74
Stock option exercises and issuance of stock (in shares)	200,395
Employee stock purchase plan	$ 1	279			280
Employee stock purchase plan (in shares)	135,985
Stock based compensation expense		3,878			3,878
Change in unrealized gain (loss) on marketable securities			(35)		(35)
Net loss				(24,600)	(24,600)
Balance at Dec. 31, 2013	$ 627	504,884	67	(444,952)	60,626
Balance (in shares) at Dec. 31, 2013	62,736,207
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted shares issued net of forfeitures and shares redeemed for taxes
Restricted shares issued net of forfeitures and shares redeemed for taxes (in shares)	(5,257)
Employee stock purchase plan	$ 1	104			105
Employee stock purchase plan (in shares)	90,831
Stock based compensation expense		3,282			3,282
Change in unrealized gain (loss) on marketable securities			(77)		(77)
Net loss				(23,391)	(23,391)
Balance at Dec. 31, 2014	$ 628	508,270	(10)	(468,343)	$ 40,545
Balance (in shares) at Dec. 31, 2014	62,821,781				62,821,781
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted shares issued net of forfeitures and shares redeemed for taxes
Restricted shares issued net of forfeitures and shares redeemed for taxes (in shares)	13,242
Employee stock purchase plan	$ 1	133			$ 134
Employee stock purchase plan (in shares)	104,757
Stock based compensation expense		2,261			2,261
Change in unrealized gain (loss) on marketable securities			13		13
Net loss				(13,774)	(13,774)
Balance at Dec. 31, 2015	$ 629	$ 510,664	$ 3	$ (482,117)	$ 29,179
Balance (in shares) at Dec. 31, 2015	62,939,780				62,939,780

STATEMENTS OF CASH FLOWS

STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net loss	$ (13,774)	$ (23,391)	$ (24,600)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	161	603	864
Amortization of premium/discount on marketable securities	464	1,120	2,144
Amortization of deferred gain on sale leaseback	(232)	(552)	(552)
Non-cash stock compensation	2,261	3,282	3,943
Gain on auction rate securities		(254)	(57)
Gain on sale of property and equipment	(277)	(388)
Impairment of property and equipment		280
Changes in operating assets and liabilities:
Prepaid expenses and other assets	1,029	(30)	(363)
Accounts payable and accrued expenses	(713)	(1,523)	(1,693)
Deferred revenue	(11,079)	(10,929)	(13,366)
Net cash used in operating activities	(22,160)	(31,782)	(33,680)
Cash flows from investing activities:
Purchases of marketable securities	(36,978)	(33,366)	(40,581)
Proceeds from sale or maturity of marketable securities	60,479	63,189	75,224
Proceeds from sale of property and equipment	298	500
Purchases of property and equipment	(315)
Net cash provided by investing activities	23,484	30,323	34,643
Cash flows from financing activities:
Payment of notes payable		(1,700)
Proceeds from stock option exercises and employee stock plan purchases	134	105	289
Net cash provided by (used in) financing activities	134	(1,595)	289
Net increase (decrease) in cash and cash equivalents	1,458	(3,054)	1,252
Cash and cash equivalents, beginning of period	12,525	15,579	14,327
Cash and cash equivalents, end of period	13,983	12,525	15,579
Supplemental Cash Flow Information [Abstract]
Interest paid	$ 0	$ 35	$ 32
Income Taxes Paid

ORGANIZATION AND NATURE OF OPER

ORGANIZATION AND NATURE OF OPERATIONS	12 Months Ended
	Dec. 31, 2015
Organization and Nature Of Operations [Abstract]
ORGANIZATION AND NATURE OF OPERATIONS	1. ORGANIZATION AND NATURE OF OPERATIONS We are a biopharmaceutical company engaged in the research and development of innovative therapeutics to treat cancers and rare diseases. Our mission is to discover, develop and commercialize novel small molecule drugs in areas of high unmet need that will dramatically extend and improve the lives of our patients. These drugs target biological pathways implicated in a wide range of cancers and certain non-oncology indications. Our discovery and development efforts are guided, when possible, by an understanding of the role of biomarkers, which are indicators of a particular biological condition or process and may predict the clinical benefit of our compounds in defined patient populations. Our proprietary clinical-stage pipeline consists of four drug candidates, all of which are in targeted patient populations making ArQule a leader among companies our size in precision medicine. Our lead product candidate is tivantinib (ARQ 197), an orally administered, small molecule inhibitor of the c-Met receptor tyrosine kinase (“MET”) and its biological pathway. MET is a promising target for cancer therapy, based on its multiple roles in cancerous cell proliferation, tumor spread, new blood vessel formation and resistance to certain drug therapies. We and our partners, Daiichi Sankyo Co., Ltd. (“Daiichi Sankyo”) and Kyowa Hakko Kirin Co., Ltd. (“Kyowa Hakko Kirin”), are implementing a worldwide clinical development program with tivantinib. Our strategy is to focus on the most promising indications within our clinical programs based upon continually generated and updated clinical and pre-clinical data. Our lead indication is liver cancer (“hepatocellular carcinoma” or “HCC”), and we are currently conducting two Phase 3 trials with our partners. We have also completed earlier-stage single agent and combination therapy trials and pre-clinical experiments with tivantinib and other anti-cancer agents that may provide data to support trials in additional indications. We have licensed commercial rights to tivantinib for human cancer indications to Daiichi Sankyo in the U.S., Europe, South America and the rest of the world, excluding Japan and certain other Asian countries, where we have licensed commercial rights to Kyowa Hakko Kirin. Our agreements with these partners provide for possible future milestone payments, royalties on product sales, and development funding, in addition to significant payments that we have already received. To date we have received $100 million in upfront and milestone payments from Daiichi Sankyo, $15 million of which was related to the first patient enrolled in the METIV-HCC trial. That milestone was netted against our cumulative share of Phase 3 collaboration costs in 2013, and consequently we did not receive any cash proceeds from this milestone. To date, we have received $48 million in upfront and milestone payments from Kyowa Hakko Kirin. Our proprietary pipeline of product candidates is directed toward molecular targets and biological processes with demonstrated roles in the development of both human cancers and rare, non-oncology diseases. These product candidates include: ARQ 092, designed to inhibit the AKT serine/threonine kinase; ARQ 087, a multi-kinase inhibitor designed to preferentially inhibit the fibroblast growth factor receptor (“FGFR”) family; and ARQ 761, a Beta lapachone analog being evaluated in investigator-sponsored testing as a promoter of NQO1-mediated programmed cancer cell necrosis. We expect to add to our proprietary pipeline with the initiation of a Phase 1 clinical trial in oncology with our next generation AKT inhibitor, ARQ 751, in the first half of 2016. Specific tumor types and biomarkers have been identified to guide our clinical testing, based on analyses of Phase 1a anti-cancer activity in humans, preclinical findings and scientific literature. Our uses of cash for operating activities have primarily consisted of salaries and wages for our employees, facility and facility-related costs for our offices and laboratories, fees paid in connection with preclinical and clinical studies, laboratory supplies and materials, and professional fees. The sources of our cash flow from operating activities have consisted primarily of payments received from our collaborators for services performed or upfront payments for future services. For each of the years ended December 31, 2015, 2014, and 2013 our net use of cash of   $22.2 million, $31.8 million, and $33.7 million, respectively was primarily driven by the difference between payments for operating expenses and cash receipts from our collaborators. Our cash requirements may vary materially from those now planned depending upon the results of our drug discovery and development strategies, our ability to enter into additional corporate collaborations and the terms of such collaborations, results of research and development, unanticipated required capital expenditures, competitive and technological advances, acquisitions and other factors. We cannot guarantee that we will be able to develop any of our drug candidates into a commercial product. It is likely we will need to raise additional capital or incur indebtedness to continue to fund our operations in the future. Our ability to raise additional funds will depend on financial, economic and market conditions, and due to global capital and credit market conditions or for other reasons, we may be unable to raise capital when needed, or on terms favorable to us. If necessary funds are not available, we may have to delay, reduce the scope of, or eliminate some of our development programs, potentially delaying the time to market for any of our product candidates.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Significant accounting policies followed in the preparation of these financial statements are as follows: Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates. Cash Equivalents and Marketable Securities We consider all highly liquid investments purchased within three months of original maturity date to be cash equivalents. We invest our available cash primarily in commercial paper, money market funds and U.S. Treasury bill funds. We generally classify our marketable securities as available-for-sale at the time of purchase and re-evaluate such designation as of each balance sheet date. The Company classifies its investments as either current or long-term based upon the investments’ contractual maturities and the Company’s ability and intent to convert such instruments to cash within one year. We report available-for-sale investments at fair value as of each balance sheet date and include any unrealized gains and, to the extent deemed temporary, unrealized losses in stockholders’ equity. Realized gains and losses are determined using the specific identification method and are included in other income (expense) in the statement of operations and comprehensive loss. For any of our marketable securities classified as trading securities, changes in the fair value of those securities are recorded as other income (expense) in the statement of operations and comprehensive loss. At December 31, 2015 we had no trading securities. We conduct quarterly reviews to determine the fair value of our investment portfolio and to identify and evaluate each investment that has an unrealized loss, in accordance with the meaning of other-than-temporary impairment and its application to certain investments. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. In the event that the cost basis of a security exceeds its fair value, we evaluate, among other factors, the duration of the period that, and extent to which, the fair value is less than cost basis, the financial health of and business outlook for the issuer, including industry and sector performance, and operational and financing cash flow factors, overall market conditions and trends, our intent to sell the investment and if it is more likely than not that we would be required to sell the investment before its anticipated recovery. Unrealized losses on available-for-sale securities that are determined to be temporary, and not related to credit loss, are recorded in accumulated other comprehensive income (loss). For available-for-sale debt securities with unrealized losses, we perform an analysis to assess whether we intend to sell or whether we would more likely than not be required to sell the security before the expected recovery of the amortized cost basis. Where we intend to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary and the full amount of the unrealized loss is reflected in the statement of operations and comprehensive loss as an impairment loss. Regardless of our intent to sell a security, we perform additional analysis on all securities with unrealized losses to evaluate losses associated with the creditworthiness of the security. We did not recognize any other-than-temporary impairments during the years ended December 31, 2015, 2014 or 2013. Credit losses are identified where we do not expect to receive cash flows sufficient to recover the amortized cost basis of a security. Fair Value of Financial Instruments At December 31, 2015 and 2014 our financial instruments consist of cash, cash equivalents, investments in corporate debt securities, accounts payable, and accrued expenses. At December 31, 2015 and 2014 our financial instruments also included marketable securities which are reported at fair value. Non-refundable Advance Payments for Research and Development Non-refundable advance payments for goods or services that will be used or rendered for future research and development activities are initially deferred and capitalized. Related expenses (or contra-revenues) are then recognized as expense (or contra-revenue) as the goods are delivered and consumed or the related services are performed. Property and Equipment Property and equipment are recorded at cost and depreciated using the straight-line method over their estimated useful lives. Assets under capital leases and leasehold improvements are amortized over the shorter of their estimated useful lives or the term of the respective leases by use of the straight-line method. Maintenance and repair costs are expensed as incurred. Depreciation and amortization expense for the years ended December 31, 2015, 2014 and 2013 was $161, $603, and $864, respectively. Revenue Recognition—Research and Development Revenue Research and development revenue is generated primarily through collaborative research and development agreements. The terms of the agreements may include nonrefundable upfront payments, funding for research and development, milestone payments and royalties on any product sales derived from collaborations. The Company adopted the FASB issued ASU No. 2010-17, Revenue Recognition—Milestone Method Research and development payments associated with our collaboration agreements in effect prior to January 1, 2011 are recognized as research and development revenue using the contingency adjusted performance model. Under this model, when payments are earned, revenue is immediately recognized on a pro-rata basis in the period we achieve the milestone based on the time elapsed from inception of the agreement to the time the milestone is earned over the estimated duration of the development period under the agreement. Thereafter, the remaining portion of the milestone payment is recognized on a straight-line basis over the remaining estimated development period under the agreement. This estimated development period may ultimately be shorter or longer depending upon the outcome of the development work, resulting in accelerated or deferred recognition of the development revenue. Royalty payments will be recognized as revenue when earned. The costs associated with satisfying research and development contracts are included in research and development expense as incurred. On November 10, 2011, we and Daiichi Sankyo announced the execution of a license agreement for the development of a new AKT inhibitor, ARQ 092. The license agreement provided exclusive rights to Daiichi Sankyo for the development, manufacturing and marketing of ARQ 092 on a worldwide basis. Following the termination of this agreement, ARQ 092 has become our proprietary asset, and Daiichi Sankyo has no further financial or other obligations or rights related to this program. Revenue for this agreement was recognized using Financial Accounting Standards Board Accounting Standards Update No. 2009-13, Multiple-Deliverable Revenue Arrangements Research and Development Costs Costs of research and development, which are expensed as incurred, are comprised of the following types of costs incurred in performing research and development activities and those incurred in connection with research and development revenue: salaries and benefits, allocated overhead and occupancy costs, clinical trial and related clinical manufacturing costs, contract services, and other outside costs. Impairment or Disposal of Long-Lived Assets We assess our long-lived assets for impairment whenever events or changes in circumstances (a “triggering event”) indicate that the carrying value of a group of long-lived assets may not be recoverable. If such circumstances are determined to exist, an estimate of undiscounted future cash flows produced by the long-lived asset, including its eventual residual value, is compared to the carrying value to determine whether impairment exists. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the assets, the assets are written-down to their estimated fair values. As a result of our restructuring in 2014, we recognized an impairment charge related to our long-lived assets of $280. We did not recognize any impairment charges related to our long-lived assets during 2015 or 2013. Segment Data The chief operating decision maker uses aggregated- financial information in determining how to allocate resources and assess performance. For this reason, we have determined that we are principally engaged in one operating segment. See Note 13 with respect to significant customers. Substantially all of our revenue since inception has been generated in the U.S. and all of our long-lived assets are located in the U.S. Other Income Other income in 2015 includes a gain of  $277 from the sale of property and equipment. Other income in 2014 includes a gain of  $254 upon the redemption of  $2,100 of our remaining auction rate securities at face value, and a gain of  $388 from the sale of property and equipment. Other income in 2013 a gain from the increase in fair value of our auction rate securities of  $57. Income Taxes Income taxes have been accounted for using the asset and liability method. Under the asset and liability method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance against deferred tax assets is recorded if, based upon the weight of all available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. For uncertain tax positions that meet “a more likely than not” threshold, the Company recognizes the benefit of uncertain tax positions in the financial statements. Earnings (Loss) Per Share The computations of basic and diluted earnings (loss) per common share are based upon the weighted average number of common shares outstanding and potentially dilutive securities. Potentially dilutive securities include stock options. Options to purchase 8,305,950, 7,724,614 and 7,511,814 shares of common stock were not included in the 2015, 2014 and 2013 computations of diluted net loss per share, respectively, because inclusion of such shares would have an anti-dilutive effect. Stock-Based Compensation Our stock-based compensation cost is measured at the grant date, based on the calculated fair value of the award, and is recognized as an expense over the employees’ requisite service period (generally the vesting period of the equity grant). We estimate the fair value of stock options using the Black-Scholes valuation model. Key input assumptions used to estimate the fair value of stock options include the exercise price of the award, expected option term, expected volatility of our stock over the option’s expected term, risk-free interest rate over the option’s expected term, and the expected annual dividend yield. We believe that the valuation technique and approach utilized to develop the underlying assumptions are appropriate in calculating the fair values of our stock options granted. The following table presents stock-based compensation expense for the years ended December 31, 2015, 2014 and 2013 included in our Statements of Operations and Comprehensive Loss: ​ ​ ​ 2015 ​ ​ 2014 ​ ​ 2013 ​ Research and development ​ ​ ​ $ 682 ​ ​ ​ ​ $ 1,016 ​ ​ ​ ​ $ 1,315 ​ ​ General and administrative ​ ​ ​ ​ 1,579 ​ ​ ​ ​ ​ 2,183 ​ ​ ​ ​ ​ 2,489 ​ ​ Restructuring ​ ​ ​ ​ — ​ ​ ​ ​ ​ 83 ​ ​ ​ ​ ​ 139 ​ ​ Total stock-based compensation expense ​ ​ ​ $ 2,261 ​ ​ ​ ​ $ 3,282 ​ ​ ​ ​ $ 3,943 ​ ​ ​ In the years ended December 31, 2015, 2014 and 2013, no stock-based compensation expense was capitalized and there were no recognized tax benefits associated with the stock-based compensation charges. The fair value of stock options and employee stock purchase plan shares granted in the years ended December 31, 2015, 2014 and 2013 respectively were estimated on the grant date using the Black-Scholes option-pricing model with the following assumptions: ​ ​ ​ 2015 ​ ​ 2014 ​ ​ 2013 ​ Dividend yield(1) ​ ​ 0.0%​ ​ ​ 0.0%​ ​ ​ 0.0%​ ​ Weighted average expected volatility factor(2) ​ ​ 66%​ ​ ​ 67%​ ​ ​ 73%​ ​ Risk free interest(3) ​ ​ 1.3–1.7%​ ​ ​ 1.5–1.8%​ ​ ​ 0.8–1.7%​ ​ Expected term, excluding options issued pursuant to the Employee Stock Purchase Plan(4) ​ ​ 5.6–6.8 years​ ​ ​ 5.8–6.9 years​ ​ ​ 5.9–7.1 years​ ​ Expected term—Employee Stock Purchase Plan(5) ​ ​ 6 months​ ​ ​ 6 months​ ​ ​ 6 months​ ​ ​ (1) We have historically not paid dividends on our common stock and we do not anticipate paying any dividends in the foreseeable future. ​ (2) Measured using an average of historical daily price changes of our stock over a period equal to our expected term. ​ (3) The risk-free interest rate for periods equal to the expected term of share option based on the U.S. Treasury yield in effect at the time of grant. ​ (4) The expected term is the number of years that we estimate, based on historical experience, that options will be outstanding before exercise or cancellation. The range in expected term is the result of certain groups of employees exhibiting different exercising behavior. ​ (5) The expected term of options issued in connection with our Employee Stock Purchase Plan is 6 months based on the terms of the plan. ​ 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, we believe that the impact of recently issued standards that are not yet effective will not have a material impact on our financial position or results of operations upon adoption. In August 2014, the FASB issued Accounting Standard Update (“ASU”) 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. Under the new guidance, management will be required to assess an entity’s ability to continue as a going concern, and to provide related footnote disclosures in certain circumstances. The provisions of this ASU are effective for annual periods beginning after December 15, 2016, and for annual and interim periods thereafter. We are currently evaluating the potential impact that this ASU may have on our disclosures. In June 2014, the FASB issued ASU No. 2014-12, “Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period.” This ASU requires a reporting entity to treat a performance target that affects vesting and that could be achieved after the requisite service period as a performance condition, and apply existing guidance under the Stock Compensation Topic of the ASC as it relates to awards with performance conditions that affect vesting to account for such awards. The provisions of this ASU are effective for interim and annual periods beginning after December 15, 2015. We are currently evaluating the potential impact that this ASU may have on our financial position and results of operations. During the quarter ended June 30, 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers” (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which delayed the effective date of the new standard from January 1, 2017 to January 1, 2018. The FASB also agreed to allow entities to choose to adopt the standard as of the original effective date. We are currently evaluating the method of adoption and the potential impact that Topic 606 may have on our financial position and results of operations.

COLLABORATIONS AND ALLIANCES

COLLABORATIONS AND ALLIANCES	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation Of Financial Statements [Abstract]
COLLABORATIONS AND ALLIANCES	3. COLLABORATIONS AND ALLIANCES Daiichi Sankyo Tivantinib Agreement On December 18, 2008, we entered into a license, co-development and co-commercialization agreement with Daiichi Sankyo to conduct research, clinical trials and the commercialization of tivantinib in human cancer indications in the U.S., Europe, South America and the rest of the world, excluding Japan, China (including Hong Kong), South Korea and Taiwan, where Kyowa Hakko Kirin has exclusive rights for development and commercialization. The agreement provides for a $60 million cash upfront licensing payment from Daiichi Sankyo to us, which we received in December 2008, and an additional $560 million in potential development and sales milestone payments offset by our share of Phase 3 costs. On November 3, 2015, the Company announced that it had exercised its option with Daiichi Sankyo to co-commercialize tivantinib in the United States (the “Co-Commercialization Option”), pursuant to the agreement. Subject to the receipt of regulatory approvals, the first commercial indication for tivantinib under the Co-Commercialization Option is anticipated to be second line HCC. The parties have a prescribed period to conclude a co-commercialization agreement in accordance with the terms of the agreement which is expected to occur in the late first quarter or early second quarter of 2016. If the METIV-HCC trial is successful, and tivantinib is approved in second line HCC, the agreement provides that the Company will receive a total of $55 million in milestone payments for the official acceptance of drug approval applications by FDA and the European Medicines Agency (“EMA”) in this first indication, plus an additional $100 million in combined milestones tied to receipt of commercialization regulatory approval by the FDA and the first commercial sale in the UK, Germany, France, Italy or Spain. These milestones, totaling $155 million, will be partially offset by Phase 3 costs owed to Daiichi Sankyo by the Company at the time of approval in the US or EU. At December 31, 2015, the Company’s share of these Phase 3 costs totaled $61.4 million. The agreement also provides that the Company will receive tiered double digit royalties on net sales of tivantinib throughout the territory. Given the anticipated commercial market for second line HCC, the Company expects to earn royalties on net sales for this indication at the baseline contractual rate of 20 percent. We and Daiichi Sankyo will share equally the costs of Phase 2 and Phase 3 clinical studies, with our share of Phase 3 costs payable solely from milestone and royalty payments by Daiichi Sankyo. Under the terms of our tivantinib collaboration agreement with Daiichi Sankyo we share development costs equally with our share of Phase 3 costs funded solely from milestones and royalties. In each quarter the tivantinib collaboration costs we incur are compared with those of Daiichi Sankyo. If our costs for the quarter exceed Daiichi Sankyo’s, we recognize revenue on the amounts due to us under the contingency adjusted performance model. Revenue is calculated on a pro-rata basis using the time elapsed from inception of the agreement over the estimated duration of the development period under the agreement. If our costs for the quarter are less than those of Daiichi Sankyo’s, we report the amount due to Daiichi Sankyo as contra-revenue in that quarter. To the extent that our share of Phase 3 collaboration costs exceeds the amount of milestones and royalties received, that excess is netted against future milestones and royalties if and when earned and is not reported as contra-revenue. Our cumulative share of the Daiichi Sankyo Phase 3 costs through December 31, 2015 totaled $101.4 million. We received a milestone of  $25 million in February 2011 upon enrolling the first patient in the MARQUEE trial, the cash proceeds of which were subsequently applied to our share of Phase 3 collaboration costs. On January 31, 2013, we announced that the first patient had been enrolled in the pivotal Phase 3 METIV trial of tivantinib, entitling us to a $15 million milestone. That $15 million milestone was also netted against our cumulative share of Phase 3 collaboration costs in 2013, and consequently we did not receive any cash proceeds from this milestone. Our cumulative share of Phase 3 collaboration costs has exceeded the amount of milestones received through December 31, 2015 by $61.4 million which will be netted against future milestones and royalties, if any, when earned and has not been reported as contra-revenue. In 2015, we recognized net research and development revenue of  $0.1 million related to our non-Phase 3 tivantinib collaboration costs which included $0.2 million of revenue and contra-revenue of  $0.1 million. In 2014, we recognized net research and development revenue of $0.2 million related to our non-Phase 3 tivantinib collaboration costs which included $0.4 million of revenue and contra-revenue of  $0.2 million. In 2013, we recognized net contra-revenue of $0.4 million related to our non-Phase 3 tivantinib collaboration costs which included contra-revenue of  $0.7 million and $0.3 million of revenue. The duration and termination of the agreement are tied to future events. Unless earlier terminated due to breach, insolvency or upon 90 days’ notice if prior to Phase 3 clinical trials or 180 days’ notice if on or after the beginning of Phase 3 clinical trials by Daiichi Sankyo, the agreement shall continue until the later of  (i) such time as Daiichi Sankyo is no longer developing at least one licensed product or (ii) if Daiichi Sankyo has commercialized a licensed product or products, such time as all royalty terms for all licensed products have ended. The royalty term, on a country-by-country basis for a product, ends as of the later of (i) the expiration of the last valid claim under a patent covering the manufacture, use, or sale of a licensed product or (ii) a certain number of years from the date of the commercial sale of the licensed product in such country. Revenue for this agreement is recognized using the contingency-adjusted performance model. Through September 30, 2012, revenue was recognized based upon an estimated development period through December 2013. As a result of the October 2012 decision to discontinue the MARQUEE trial, the development period as of October 1, 2012 was extended to June 2015. Commencing with the fourth quarter of 2012 and through the third quarter of 2013 revenue was recognized over that development period. In the fourth quarter of 2013, following a recommendation by the Data Monitoring Committee that the METIV-HCC trial continue with patients receiving a lower dose of tivantinib than the dose originally employed in the trial, we reviewed the estimated development period and extended it to June 2016. For the years ended December 31, 2015, 2014 and 2013, $5.5 million, net of   $0.1 million of contra-revenue, $5.6 million, net of   $0.2 million of contra-revenue and $7.2 million, net of   $0.7 million of contra-revenue respectively, were recognized as revenue. At December 31, 2015 and 2014, $2.7 million and $8.1 million respectively, remained in deferred revenue. Kyowa Hakko Kirin Licensing Agreement On April 27, 2007, we entered into an exclusive license agreement with Kyowa Hakko Kirin to develop and commercialize tivantinib in Japan and parts of Asia. A $3 million portion of an upfront licensing fee was received by the Company under this agreement in the first quarter of 2007, and an additional $27 million in upfront licensing fees was received on May 7, 2007. The agreement includes $123 million in upfront and potential development milestone payments from Kyowa Hakko Kirin to ArQule, including the $30 million cash upfront licensing payments. In February 2008, we received a $3 million milestone payment from Kyowa Hakko Kirin. Upon commercialization, ArQule will receive tiered royalties in the mid-teen to low-twenty percent range from Kyowa Hakko Kirin on net sales of tivantinib. Kyowa Hakko Kirin will be responsible for all clinical development costs and commercialization of the compound in certain Asian countries, consisting of Japan, China (including Hong Kong), South Korea and Taiwan. In July 2010, we announced the initiation of a Phase 2 trial with tivantinib by Kyowa Hakko Kirin in gastric cancer, for which we received a $5 million milestone payment in September 2010. In August 2011, Kyowa Hakko Kirin announced the initiation of the Phase 3 ATTENTION trial. Dosing of the first patient in this trial triggered a $10 million milestone payment, which we received in August 2011. The milestone payment was recorded as deferred revenue and is being recognized as revenue using the contingency-adjusted performance model with an estimated development period through April 2016. On February 4, 2014, Kyowa Hakko Kirin announced the initiation of the Phase 3 JET-HCC trial. There were no milestone payments associated with the initiation of this trial. In addition to the upfront and possible regulatory milestone payments totaling $123 million, the Company will be eligible for future milestone payments based on the achievement of certain levels of net sales. The Company will recognize the payments, if any, as revenue in accordance with the contingency-adjusted performance model. As of December 31, 2015, the Company had not recognized any revenue from these sales milestone payments, and there can be no assurance that it will do so in the future. The duration and termination of the agreement are tied to future events. Unless earlier terminated due to breach, insolvency or upon 90 days’ notice by Kyowa Hakko Kirin, the agreement terminates on the date that the last royalty term expires in all countries in the territory. The royalty term ends as of the later of  (i) the expiration of the last pending patent application or expiration of the patent in the country covering the manufacture, use, or sale of a licensed product or (ii) a certain number of years from the date of the commercial launch in such country of such license product. Revenue for this agreement is recognized using the contingency-adjusted performance model with an estimated development period through April 2016. For each of the years ended December 31, 2015, 2014, and 2013, $5.7 million was recognized as revenue. At December 31, 2015 and 2014, $1.9 million and $7.6 million respectively, remained in deferred revenue. Beryllium Discovery Corp. Agreement In May 2015, we entered into a collaborative research and development agreement with Beryllium Discovery Corp. (“Beryllium”). Pursuant to the agreement, we will jointly focus on the identification and preclinical development of inhibitors of PD-1 and PDL-1. We and Beryllium will each be responsible for our respective internal and outsourcing costs during pre-clinical development. Following lead optimization of any potential drug candidates, we and Beryllium will jointly decide whether to advance compounds into GLP/toxicology and clinical testing, initially on a shared cost basis, provided that we will have the right to advance compounds on our own should Beryllium vote against such advancement. The agreement also provides that we will be responsible for clinical development and commercialization of product candidates that are not out-licensed. Beryllium will have the right to participate financially throughout the program but will also have the option to opt out at certain times and receive a royalty. The agreement will terminate after the last payment obligation is satisfied, or prior to that upon 60-days’ notice by either party.

MARKETABLE SECURITIES AND FAIR

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2015
Marketable Securities and Fair Value Measurements [Abstract]
MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS	4. MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS We generally classify our marketable securities as available-for-sale at the time of purchase and re-evaluate such designation as of each balance sheet date. Since we generally intend to convert them into cash as necessary to meet our liquidity requirements our marketable securities are classified as cash equivalents if the original maturity, from the date of purchase, is ninety days or less and as short-term investments if the original maturity, from the date of purchase, is in excess of ninety days but less than one year. Our marketable securities are classified as long-term investments if the maturity date is in excess of one year of the balance sheet date. We report available-for-sale investments at fair value as of each balance sheet date and include any unrealized gains and, to the extent deemed temporary, unrealized losses in stockholders’ equity. Realized gains and losses are determined using the specific identification method and are included in other income (expense) in the statement of operations and comprehensive loss. Our auction rate securities are classified as trading securities and any changes in the fair value of those securities are recorded as other income (expense) in the statement of operations and comprehensive loss. We conduct quarterly reviews to determine the fair value of our investment portfolio and to identify and evaluate each investment that has an unrealized loss, in accordance with the meaning of other-than-temporary impairment and its application to certain investments. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. In the event that the cost basis of a security exceeds its fair value, we evaluate, among other factors, the duration of the period that, and extent to which, the fair value is less than cost basis, the financial health of and business outlook for the issuer, including industry and sector performance, and operational and financing cash flow factors, overall market conditions and trends, our intent to sell the investment and if it is more likely than not that we would be required to sell the investment before its anticipated recovery. Unrealized losses on available-for-sale securities that are determined to be temporary, and not related to credit loss, are recorded in accumulated other comprehensive income (loss). For available-for-sale debt securities with unrealized losses, we perform an analysis to assess whether we intend to sell or whether we would more likely than not be required to sell the security before the expected recovery of the amortized cost basis. Where we intend to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary and the full amount of the unrealized loss is reflected in the statement of operations and comprehensive loss as an impairment loss. Regardless of our intent to sell a security, we perform additional analysis on all securities with unrealized losses to evaluate losses associated with the creditworthiness of the security. Credit losses are identified where we do not expect to receive cash flows sufficient to recover the amortized cost basis of a security. We invest our available cash primarily in commercial paper, money market funds, and U.S. Treasury bill funds and U.S. federal and state agency backed certificates that have investment grade ratings. During 2014 all $2.1 million of our auction rate securities were redeemed at full face value. ArQule’s marketable securities portfolio included $2.1 million (at cost) at December 31, 2013 invested in auction rate securities. The following is a summary of the fair value of available-for-sale marketable securities we held at December 31, 2015 and December 31, 2014: December 31, 2015 ​ ​ Amortized Cost ​ ​ Gross Gains ​ ​ Gross Losses ​ ​ Fair Value ​ Security type ​ ​ ​ ​ ​ Corporate debt securities-short term ​ ​ ​ $ 24,786 ​ ​ ​ ​ $ 13 ​ ​ ​ ​ $ (10 ) ​ ​ ​ ​ $ 24,789 ​ ​ Corporate debt securities-long term ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Total available-for-sale marketable securities ​ ​ ​ $ 24,786 ​ ​ ​ ​ $ 13 ​ ​ ​ ​ $ (10 ) ​ ​ ​ ​ $ 24,789 ​ ​ ​ December 31, 2014 ​ ​ Amortized Cost ​ ​ Gross Gains ​ ​ Gross Losses ​ ​ Fair Value ​ Security type ​ ​ ​ ​ ​ Corporate debt securities-short term ​ ​ ​ $ 46,690 ​ ​ ​ ​ $ 16 ​ ​ ​ ​ $ (23 ) ​ ​ ​ ​ $ 46,683 ​ ​ Corporate debt securities-long term ​ ​ ​ ​ 2,061 ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ (3 ) ​ ​ ​ ​ ​ 2,058 ​ ​ Total available-for-sale marketable securities ​ ​ ​ $ 48,751 ​ ​ ​ ​ $ 16 ​ ​ ​ ​ $ (26 ) ​ ​ ​ ​ $ 48,741 ​ ​ ​ None of our available-for-sale marketable securities were in a continuous unrealized loss position for more than 12 months at December 31, 2015 or 2014. The following tables present information about our assets that are measured at fair value on a recurring basis for the periods presented and indicates the fair value hierarchy of the valuation techniques we utilized to determine such fair value. In general, fair values determined by Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities. Fair values determined by Level 2 inputs utilize data points that are observable such as quoted prices, interest rates and yield curves. We value our level 2 investments using quoted prices for identical assets in the markets where they are traded, although such trades may not occur daily. These quoted prices are based on observable inputs, primarily interest rates. Fair values determined by Level 3 inputs are unobservable data points for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability. There were no transfers in or out of Level 1 or Level 2 measurements for the periods presented: ​ ​ ​ December 31, ​ ​ Quoted Prices in ​ ​ Significant ​ ​ Significant ​ Cash equivalents ​ ​ ​ $ 11,800 ​ ​ ​ ​ $ 11,800 ​ ​ ​ ​ $ — ​ ​ ​ ​ $ — ​ ​ Corporate debt securities-short term ​ ​ ​ ​ 24,789 ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ 24,789 ​ ​ ​ ​ ​ — ​ ​ Corporate debt securities-long term ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Total ​ ​ ​ $ 36,589 ​ ​ ​ ​ $ 11,800 ​ ​ ​ ​ $ 24,789 ​ ​ ​ ​ $ — ​ ​ ​ ​ ​ ​ December 31, ​ ​ Quoted Prices in ​ ​ Significant ​ ​ Significant ​ Cash equivalents ​ ​ ​ $ 10,740 ​ ​ ​ ​ $ 10,740 ​ ​ ​ ​ $ — ​ ​ ​ ​ $ — ​ ​ Corporate debt securities-short term ​ ​ ​ ​ 46,683 ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ 46,683 ​ ​ ​ ​ ​ — ​ ​ Corporate debt securities-long term ​ ​ ​ ​ 2,058 ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ 2,058 ​ ​ ​ ​ ​ — ​ ​ Total ​ ​ ​ $ 59,481 ​ ​ ​ ​ $ 10,740 ​ ​ ​ ​ $ 48,741 ​ ​ ​ ​ $ — ​ ​ ​

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	5. PROPERTY AND EQUIPMENT Property and equipment consist of the following at December 31, 2015 and 2014: ​ ​ ​ USEFUL ​ ​ 2015 ​ ​ 2014 ​ Machinery and equipment ​ ​ 5​ ​ ​ ​ $ 1,939 ​ ​ ​ ​ $ 2,562 ​ ​ Leasehold improvements ​ ​ 3–10​ ​ ​ ​ ​ 232 ​ ​ ​ ​ ​ 1,005 ​ ​ Furniture and fixtures ​ ​ 7​ ​ ​ ​ ​ 40 ​ ​ ​ ​ ​ 1,175 ​ ​ Computer equipment ​ ​ 3​ ​ ​ ​ ​ 2,482 ​ ​ ​ ​ ​ 3,604 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,693 ​ ​ ​ ​ ​ 8,346 ​ ​ Less: Accumulated depreciation and amortization ​ ​ ​ ​ ​ ​ ​ 4,427 ​ ​ ​ ​ ​ 8,213 ​ ​ Net property and equipment ​ ​ ​ ​ ​ ​ $ 266 ​ ​ ​ ​ $ 133 ​ ​ ​ In January 2015, we entered into a lease agreement for a new headquarters facility in Burlington, MA of approximately 15,000 square feet. The lease commenced on May 1, 2015 for a term of five years and three months with an average annual rental rate of $455. In conjunction with the move to our new facility in 2015, we recognized a gain of  $277 from the sale of property and equipment. In 2015, we wrote off property and equipment with an original cost and accumulated depreciation of $4.0 million. As a result of our restructuring in 2014, we recognized an impairment charge related to our property and equipment of  $280. In 2014, we also recognized a gain of  $388 from the sale of property and equipment. In anticipation of our move to our new leased facility, property and equipment with an original cost of  $10.4 million and accumulated depreciation of  $10.3 million were written off in 2014.

OTHER ASSETS

OTHER ASSETS	12 Months Ended
	Dec. 31, 2015
Other Assets [Abstract]
OTHER ASSETS	6. OTHER ASSETS Other assets include the following at December 31, 2015 and 2014: ​ ​ ​ 2015 ​ ​ 2014 ​ Security deposits ​ ​ ​ $ 252 ​ ​ ​ ​ $ 102 ​ ​ Total other assets ​ ​ ​ $ 252 ​ ​ ​ ​ $ 102 ​ ​ ​

ACCOUNTS PAYABLE AND ACCRUED EX

ACCOUNTS PAYABLE AND ACCRUED EXPENSES	12 Months Ended
	Dec. 31, 2015
Payables and Accruals [Abstract]
ACCOUNTS PAYABLE AND ACCRUED EXPENSES	7. ACCOUNTS PAYABLE AND ACCRUED EXPENSES Accounts payable and accrued expenses include the following at December 31, 2015 and 2014: ​ ​ ​ 2015 ​ ​ 2014 ​ Accounts payable ​ ​ ​ $ 186 ​ ​ ​ ​ $ 259 ​ ​ Accrued payroll ​ ​ ​ ​ 1,956 ​ ​ ​ ​ ​ 2,130 ​ ​ Accrued outsourced pre-clinical and clinical fees ​ ​ ​ ​ 3,273 ​ ​ ​ ​ ​ 3,753 ​ ​ Accrued professional fees ​ ​ ​ ​ 516 ​ ​ ​ ​ ​ 157 ​ ​ Other accrued expenses ​ ​ ​ ​ 303 ​ ​ ​ ​ ​ 648 ​ ​ ​ ​ ​ ​ $ 6,234 ​ ​ ​ ​ $ 6,947 ​ ​ ​

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2015
Stockholders' Equity Note [Abstract]
STOCKHOLDERS' EQUITY	8. STOCKHOLDERS’ EQUITY Preferred Stock We are authorized to issue up to one million shares of preferred stock. As of December 31, 2015 and 2014, there were no outstanding shares of preferred stock. Our Board of Directors will determine the terms of the preferred stock if and when the shares are issued. Common Stock Our amended Certificate of Incorporation authorizes the issuance of up to 100 million shares of  $0.01 par value common stock. At December 31, 2015, we have 253,460 common shares reserved for future issuance under the Employee Stock Purchase Plan (“Purchase Plan”) and 4,311,474 for the exercise of common stock options pursuant to the 2014 Equity Incentives Plan (“Equity Incentives Plan”) , the Amended and Restated 1994 Equity Incentive Plan and the Amended and Restated 1996 Director Stock Option Plan (“Director Plan”).

EQUITY INCENTIVE PLANS

EQUITY INCENTIVE PLANS	12 Months Ended
	Dec. 31, 2015
Disclosure Of Compensation Related Costs, Share-Based Payments [Abstract]
EQUITY INCENTIVE PLANS	9. EQUITY INCENTIVE PLANS In 2014, our stockholders approved our Equity Incentives Plan and authorized 3,750,000 shares of common stock for issuance pursuant to future awards under the Equity Plan. In addition, any shares from our Amended and Restated 1994 Equity Incentive Plan that expire, are cancelled or forfeited after the effective date of the Equity Incentives Plan may also be issued for future awards under the Equity Incentives Plan. All shares are awarded at the discretion of our Board of Directors in a variety of stock based forms including stock options, restricted stock and performance based stock units, and stock appreciation rights. Pursuant to the Equity Incentives Plan, incentive stock options may not be granted at less than the fair market value of our common stock at the date of the grant, and the option term may not exceed ten years. Stock options issued pursuant to the Equity Incentives Plan generally vest over four years. For holders of 10% or more of our voting stock, options may not be granted at less than 110% of the fair market value of the common stock at the date of the grant, and the option term may not exceed five years. Stock appreciation rights granted in tandem with an option shall have an exercise price not less than the exercise price of the related option. As of December 31, 2015, no stock appreciation rights have been issued. At December 31, 2015, there were 2,433,650 shares available for future grants under the Equity Incentives Plan and 1,611,324 shares available under our Amended and Restated 1994 Equity Incentive Plan. During 2014, our stockholders approved an amendment to the Director Plan to increase the number of shares available to 1,200,000. Under the terms of the Director Plan, options to purchase shares of common stock are automatically granted (A) to the Chairman of the Board of Directors (1) upon his or her initial election or appointment in the amount of 25,000 and vesting over three years and (2) upon his or her re-election or continuation on our board immediately after each annual meeting of stockholders in the amount of 25,000 and vesting one year from the date of grant, and (B) to each other Director (1) upon his or her initial election to our board in the amount of 30,000 and vesting over three years and (2) upon his or her re-election or continuation on our board in the amount of 15,000 and vesting one year from the date of grant. All options granted pursuant to the Director Plan have a term of ten years with exercise prices equal to fair market value on the date of grant. Through December 31, 2015, options to purchase 1,247,500 shares of common stock have been granted under this plan of which 820,000 shares are currently exercisable. As of December 31, 2015, 266,500 shares are available for future grant. Option activity under the Plans for the years ended December 31, 2013, 2014 and 2015 was as follows: Stock Options ​ ​ Number of Shares ​ ​ Weighted Average Exercise Price ​ Outstanding as of December 31, 2012 ​ ​ ​ ​ 7,157,458 ​ ​ ​ ​ $ 5.70 ​ ​ Granted ​ ​ ​ ​ 1,220,910 ​ ​ ​ ​ ​ 2.53 ​ ​ Exercised ​ ​ ​ ​ (3,000 ) ​ ​ ​ ​ ​ 2.35 ​ ​ Cancelled ​ ​ ​ ​ (863,554 ) ​ ​ ​ ​ ​ 4.82 ​ ​ Outstanding as of December 31, 2013 ​ ​ ​ ​ 7,511,814 ​ ​ ​ ​ $ 5.28 ​ ​ Granted ​ ​ ​ ​ 1,150,119 ​ ​ ​ ​ ​ 2.47 ​ ​ Exercised ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Cancelled ​ ​ ​ ​ (937,319 ) ​ ​ ​ ​ ​ 5.06 ​ ​ Outstanding as of December 31, 2014 ​ ​ ​ ​ 7,724,614 ​ ​ ​ ​ $ 4.89 ​ ​ Granted ​ ​ ​ ​ 1,513,850 ​ ​ ​ ​ ​ 1.25 ​ ​ Exercised ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Cancelled ​ ​ ​ ​ (932,514 ) ​ ​ ​ ​ ​ 4.82 ​ ​ Outstanding as of December 31, 2015 ​ ​ ​ ​ 8,305,950 ​ ​ ​ ​ $ 4.24 ​ ​ Exercisable as of December 31, 2015 ​ ​ ​ ​ 5,756,625 ​ ​ ​ ​ $ 5.12 ​ ​ ​ The following table summarizes information about options outstanding at December 31, 2015: ​ ​ ​ Options Outstanding ​ ​ Options Exercisable ​ Range of Exercise Prices ​ ​ Number December 31, 2015 ​ ​ Weighted Average Contractual Life ​ ​ Weighted Average Exercise Price ​ ​ Exercisable as of December 31, 2015 ​ ​ Weighted Average Exercise Price ​ $1.16–1.42 ​ ​ ​ ​ 1,206,350 ​ ​ ​ ​ ​ 9.01 ​ ​ ​ ​ $ 1.17 ​ ​ ​ ​ ​ 7,800 ​ ​ ​ ​ $ 1.16 ​ ​  1.43–2.35 ​ ​ ​ ​ 318,750 ​ ​ ​ ​ ​ 8.98 ​ ​ ​ ​ ​ 1.70 ​ ​ ​ ​ ​ 105,000 ​ ​ ​ ​ ​ 1.46 ​ ​  2.36–2.80 ​ ​ ​ ​ 1,756,703 ​ ​ ​ ​ ​ 6.94 ​ ​ ​ ​ ​ 2.55 ​ ​ ​ ​ ​ 815,072 ​ ​ ​ ​ ​ 2.56 ​ ​  2.81–5.60 ​ ​ ​ ​ 2,053,809 ​ ​ ​ ​ ​ 2.87 ​ ​ ​ ​ ​ 3.89 ​ ​ ​ ​ ​ 2,053,809 ​ ​ ​ ​ ​ 3.89 ​ ​  5.61–8.40 ​ ​ ​ ​ 2,893,338 ​ ​ ​ ​ ​ 3.92 ​ ​ ​ ​ ​ 6.93 ​ ​ ​ ​ ​ 2,697,944 ​ ​ ​ ​ ​ 6.86 ​ ​  8.41–9.45 ​ ​ ​ ​ 77,000 ​ ​ ​ ​ ​ 1.37 ​ ​ ​ ​ ​ 9.09 ​ ​ ​ ​ ​ 77,000 ​ ​ ​ ​ ​ 9.09 ​ ​ ​ ​ ​ ​ ​ 8,305,950 ​ ​ ​ ​ ​ 5.21 ​ ​ ​ ​ $ 4.24 ​ ​ ​ ​ ​ 5,756,625 ​ ​ ​ ​ $ 5.12 ​ ​ ​ The aggregate intrinsic value of options outstanding at December 31, 2015 was $1,363. The weighted average grant date fair value of options granted in year ended December 31, 2015, 2014 and 2013 was $0.77, $1.65, and $1.69, per share, respectively. No options were exercised in the years ended December 31, 2015 and 2014. The intrinsic value of options exercised in the year ended December 31, 2013, was $1. Options vested, expected to vest and exercisable at December 31, 2015 are as follows: ​ ​ ​ Options ​ ​ Weighted-Average ​ ​ Weighted-Average ​ ​ Aggregate ​ Vested and unvested expected to vest at December 31, 2015 ​ ​ ​ ​ 8,119,246 ​ ​ ​ ​ $ 4.24 ​ ​ ​ ​ ​ 5.21 ​ ​ ​ ​ $ 1,265 ​ ​ Exercisable at December 31, 2015 ​ ​ ​ ​ 5,756,625 ​ ​ ​ ​ $ 5.12 ​ ​ ​ ​ ​ 3.82 ​ ​ ​ ​ $ 83 ​ ​ The total compensation cost not yet recognized as of December 31, 2015 related to non-vested option awards was $2,545 which will be recognized over a weighted-average period of 2.3 years. During the year ended December 31, 2015, 205,980 shares were forfeited with a weighted average grant date fair value of $1.48 per share and a weighted average exercise price of $2.35 per share. During the year ended December 31, 2015, 726,534 shares expired with a weighted average grant date fair value of $3.30 per share and a weighted average exercise price of $5.52 per share. The weighted average remaining contractual life for options exercisable at December 31, 2015 was 3.8 years. In 2013, we granted 242,697 shares of restricted stock to employees, vesting annually over a four year period. No restricted stock was granted in 2015 or 2014. The weighted average fair value of the restricted stock at the time of grant in 2013 was $2.51 per share, and is being expensed ratably over the vesting period. We recognized share-based compensation expense related to restricted stock of $76, $88 and $187 for the year ended December 31, 2015, 2014 and 2013, respectively. Restricted stock activity under the equity incentives plan for the year ended December 31, 2015 was as follows: Restricted Stock ​ ​ Number of Shares ​ ​ Weighted Average Fair Value ​ Unvested as of December 31, 2014 ​ ​ ​ ​ 105,665 ​ ​ ​ ​ $ 2.51 ​ ​ Granted ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Vested ​ ​ ​ ​ (36,101 ) ​ ​ ​ ​ ​ 2.51 ​ ​ Cancelled ​ ​ ​ ​ (10,929 ) ​ ​ ​ ​ ​ 2.51 ​ ​ Unvested as of December 31, 2015 ​ ​ ​ ​ 58,635 ​ ​ ​ ​ $ 2.51 ​ ​ ​ The fair value of restricted stock vested in 2015, 2014 and 2013 was $78, $78 and $206, respectively. In July 2010, the Company amended its chief executive officer’s (the “CEO’s”) employment agreement to grant the CEO 100,000 stock options, of which 25% vested upon grant and 25% vest annually over the next three years, and a maximum of 390,000 performance-based stock units that vest upon the achievement of certain performance and market based targets. In March 2013, the Company amended its CEO’s employment agreement to modify the performance and market based targets. In February 2012, the Company amended its chief medical officer’s (the “CMO’s”) employment agreement to grant the CMO 50,000 performance-based stock units that vest upon the achievement of certain performance based targets. In March 2013, the Company amended its chief operating officer’s (the “COO’s”) employment agreement to grant the COO 125,000 performance-based stock units that vest upon the achievement of certain performance based targets. In March 2013, the Company amended its CMO’s employment agreement to grant the CMO 120,000 performance-based stock units that vest upon the achievement of certain performance based targets. Through December 31, 2015 no expense has been recorded for any performance-based stock units granted to the CEO, COO, or CMO. In 1996, the stockholders adopted the Purchase Plan. This plan enables eligible employees to exercise rights to purchase our common stock at 85% of the fair market value of the stock on the date the right was granted or the date the right is exercised, whichever is lower. Rights to purchase shares under the Purchase Plan are granted by the Board of Directors. The rights are exercisable during a period determined by the Board of Directors; however, in no event will the period be longer than twenty-seven months. The Purchase Plan is available to substantially all employees, subject to certain limitations. In 2011, our stockholders approved an amendment to the Purchase Plan to increase the aggregate number of shares of the Company’s common stock that may be issued to 2,400,000. As of December 31, 2015, 2,146,540 shares have been purchased and 253,460 shares are available for future sale under the Purchase Plan. We recognized share-based compensation expense related to the Purchase Plan of $60, $58 and $124 for the year ended December 31, 2015, 2014 and 2013, respectively.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
INCOME TAXES	10. INCOME TAXES There was no current or deferred tax expense for the years ended December 31, 2015, 2014 or 2013 due to our loss before income taxes and our valuation allowance. We have recorded a full valuation allowance against our deferred tax assets based upon the weight of available evidence, as it is more likely than not that the deferred tax assets will not be realized. The following is a reconciliation between the U.S. federal statutory rate and the effective tax rate for the years ended December 31, 2015, 2014 and 2013: ​ ​ ​ 2015 ​ ​ 2014 ​ ​ 2013 ​ Income tax (benefit) expense at statutory rate ​ ​ ​ $ (4,683 ) ​ ​ ​ ​ $ (7,953 ) ​ ​ ​ ​ $ (8,364 ) ​ ​ State tax (benefit) expense, net of Federal tax (benefit) expense ​ ​ ​ ​ (677 ) ​ ​ ​ ​ ​ (1,154 ) ​ ​ ​ ​ ​ (901 ) ​ ​ Permanent items ​ ​ ​ ​ 239 ​ ​ ​ ​ ​ 383 ​ ​ ​ ​ ​ 516 ​ ​ Effect of change in valuation allowance and State NOL expiration ​ ​ ​ ​ 4,945 ​ ​ ​ ​ ​ 9,402 ​ ​ ​ ​ ​ 10,862 ​ ​ Tax credits ​ ​ ​ ​ (74 ) ​ ​ ​ ​ ​ (678 ) ​ ​ ​ ​ ​ (2,113 ) ​ ​ Other ​ ​ ​ ​ 250 ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Tax expense (benefit) ​ ​ ​ $ — ​ ​ ​ ​ $ — ​ ​ ​ ​ $ — ​ ​ ​ The income tax effect of temporary differences comprising the deferred tax assets and deferred tax liabilities on the accompanying balance sheets is a result of the following at December 31, 2015 and 2014: ​ ​ ​ 2015 ​ ​ 2014 ​ Deferred tax assets: ​ ​ ​ Net operating loss carryforwards ​ ​ ​ $ 125,599 ​ ​ ​ ​ $ 115,747 ​ ​ Tax credit carryforwards ​ ​ ​ ​ 25,036 ​ ​ ​ ​ ​ 24,962 ​ ​ Equity based compensation ​ ​ ​ ​ 9,176 ​ ​ ​ ​ ​ 8,558 ​ ​ Book depreciation in excess of tax ​ ​ ​ ​ 35 ​ ​ ​ ​ ​ 1,352 ​ ​ Reserves and accruals ​ ​ ​ ​ 276 ​ ​ ​ ​ ​ 52 ​ ​ Deferred revenue ​ ​ ​ ​ 1,796 ​ ​ ​ ​ ​ 6,115 ​ ​ Loss on investment ​ ​ ​ ​ — ​ ​ ​ ​ ​ 194 ​ ​ Other ​ ​ ​ ​ 26 ​ ​ ​ ​ ​ 19 ​ ​ ​ ​ ​ ​ ​ 161,944 ​ ​ ​ ​ ​ 156,999 ​ ​ Valuation allowance ​ ​ ​ ​ (161,944 ) ​ ​ ​ ​ ​ (156,999 ) ​ ​ Deferred tax liabilities ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Net deferred tax assets ​ ​ ​ $ — ​ ​ ​ ​ $ — ​ ​ ​ Total valuation allowance increased by $4,945 for the year ended December 31, 2015. We have evaluated positive and negative evidence bearing upon the realizability of our deferred tax assets, which are comprised principally of federal and state net operating loss (“NOL”), net capital loss, and research and development credit carryforwards. We have determined that it is more likely than not that we will not recognize the benefits of our federal and state deferred tax assets and, as a result, we have established a full valuation allowance against our net deferred tax assets as of December 31, 2015. As of December 31, 2015, we had federal NOL, state NOL, and research and development credit carryforwards of approximately $357,122, $176,712 and $27,750 respectively, which expire at various dates through 2035. Approximately $15,020 of our federal NOL and $868 of our state NOL were generated from excess tax deductions from share-based awards, the tax benefit of which will be credited to additional paid-in-capital when the deductions reduce current taxes payable. As of December 31, 2015, and 2014 we had no unrecognized tax benefits. We do not expect that the total amount of unrecognized tax benefits will significantly increase in the next twelve months. Our policy is to recognize interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2015 and 2014, we had no accrued interest or penalties related to uncertain tax positions. Our U.S. federal tax returns for the tax years 2012 through 2015 and our state tax returns for the tax years 2012 through 2015 remain open to examination. Prior tax years remain open to the extent of net operating loss and tax credit carryforwards. Utilization of NOL and research and development credit carryforwards may be subject to a substantial annual limitation in the event of an ownership change that has occurred previously or could occur in the future pursuant to Section 382 and 383 of the Internal Revenue Code of 1986, as amended, as well as similar state provisions. An ownership change may limit the amount of NOL and research and development credit carryforwards that can be utilized annually to offset future taxable income, and may, in turn, result in the expiration of a portion of those carryforwards before utilization. In general, an ownership change, as defined by Section 382, results from transactions that increase the ownership of certain stockholders or public groups in the stock of a corporation by more than 50 percentage points over a three year period. We undertook a detailed study of our NOL and research and development credit carryforwards through January 31, 2016, to determine whether such amounts are likely to be limited by Sections 382 or 383. As a result of this analysis, we currently do not believe any Sections 382 or 383 limitations will significantly impact our ability to offset income with available NOL and research and development credit carryforwards. However, future ownership changes under Section 382 may limit our ability to fully utilize these tax benefits.

RESTRUCTURING AND OTHER COSTS

RESTRUCTURING AND OTHER COSTS	12 Months Ended
	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
RESTRUCTURING	11. RESTRUCTURING AND OTHER COSTS In July 2013, we implemented a focused reduction in our workforce of 26 positions, resulting in a remaining workforce of approximately 68 employees. This action was intended to align human and financial resources with our primary focus on clinical-stage development, while retaining our core discovery capabilities. The costs associated with this action were comprised of severance payments of  $422 and benefits continuation costs of  $89 all of which were paid by December 31, 2013. We also incurred non-cash charges of  $139 related to the modification of employee stock options. On July 30, 2014, we approved plans to restructure our operations to better align our human and financial resources with our primary focus on clinical stage development programs and to extend our cash runway. Commencing on August 4, 2014, we began to reduce our workforce from 62 to approximately 40 employees by the end of the year. Most of this reduction came from our Discovery Group, which has been engaged primarily in early-stage, pre-clinical research. The costs associated with this action were comprised of severance payments of  $662 and benefits continuation costs of  $74. In the year ended December 31, 2014, $319 of these costs was paid and the remaining amount of  $417 was paid by March 31, 2015. In addition, in the year ended December 31, 2014, we incurred non-cash charges of  $83 related to the modification of employee stock options, and $280 for impairment of property and equipment impacted by the restructuring.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	12. COMMITMENTS AND CONTINGENCIES Leases We lease a facility under a non-cancelable operating lease that terminates on July 31, 2020 and the minimum lease commitment for our leased facility is as follows: YEAR ENDING DECEMBER 31, ​ ​ OPERATING LEASES ​ 2016 ​ ​ ​ $ 529 ​ ​ 2017 ​ ​ ​ ​ 488 ​ ​ 2018 ​ ​ ​ ​ 484 ​ ​ 2019 ​ ​ ​ ​ 499 ​ ​ Thereafter ​ ​ ​ ​ 296 ​ ​ Total minimum lease payments ​ ​ ​ $ 2,296 ​ ​ ​ Rent expense under our non-cancelable operating lease was approximately $1,569 for the year ended December 31, 2015, and $2,866 for the years ended December 31, 2014 and 2013. In January 2015, we entered into a lease agreement for a new headquarters facility. The lease commenced on May 1, 2015 for a term of five years and three months with an average annual rental rate of $455. The lease obligation for the new facility is included in the table above.

CONCENTRATION OF CREDIT RISK

CONCENTRATION OF CREDIT RISK	12 Months Ended
	Dec. 31, 2015
Risks and Uncertainties [Abstract]
CONCENTRATION OF CREDIT RISK	13. CONCENTRATION OF CREDIT RISK Revenue from one customer represented approximately 49% of total revenue during 2015, 49% in 2014 and 53% in 2013. Revenue from another customer represented approximately 51% of total revenue during 2015, 51% in 2014, and 36% in 2013. Revenue from an additional customer for whom we completed a one-time research project represented approximately 11% of total revenue during 2013.

SELECTED QUARTERLY FINANCIAL DA

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)	14. SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) ​ ​ ​ FIRST ​ ​ SECOND ​ ​ THIRD ​ ​ FOURTH ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net revenues ​ ​ ​ $ 2,785 ​ ​ ​ ​ $ 3,004 ​ ​ ​ ​ $ 2,653 ​ ​ ​ ​ $ 2,797 ​ ​ Net loss ​ ​ ​ ​ (4,551 ) ​ ​ ​ ​ ​ (4,017 ) ​ ​ ​ ​ ​ (2,354 ) ​ ​ ​ ​ ​ (2,852 ) ​ ​ Basic and diluted net loss per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share ​ ​ ​ $ (0.07 ) ​ ​ ​ ​ $ (0.06 ) ​ ​ ​ ​ $ (0.04 ) ​ ​ ​ ​ $ (0.05 ) ​ ​ ​ ​ ​ FIRST ​ ​ SECOND ​ ​ THIRD ​ ​ FOURTH ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net revenues ​ ​ ​ $ 2,676 ​ ​ ​ ​ $ 2,901 ​ ​ ​ ​ $ 2,662 ​ ​ ​ ​ $ 3,015 ​ ​ Net loss ​ ​ ​ ​ (7,141 ) ​ ​ ​ ​ ​ (6,339 ) ​ ​ ​ ​ ​ (6,399 ) ​ ​ ​ ​ ​ (3,512 ) ​ ​ Basic and diluted earnings (loss) per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share ​ ​ ​ $ (0.11 ) ​ ​ ​ ​ $ (0.10 ) ​ ​ ​ ​ $ (0.10 ) ​ ​ ​ ​ $ (0.06 ) ​ ​

SUBSEQUENT EVENT

SUBSEQUENT EVENT	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
SUBSEQUENT EVENT	15. SUBSEQUENT EVENT On February 26, 2016 the Company entered into definitive stock purchase agreements with certain institutional and accredited investors for the sale of approximately 8,030,000 shares of our common stock and non-transferable options to purchase up to approximately 3,570,000 shares of our common stock for aggregate proceeds of approximately $15.3 million. Each option is exercisable for $2.50 per share, and if all options were to be exercised it would result in additional proceeds of approximately $8.9 million. All options will expire on the first anniversary of a “Regulatory Event,” which we define as the public announcement by us of the outcome of the pre-planned interim assessment to be conducted by the data monitoring committee of the METIV-HCC trial as set forth in the Special Protocol Assessment with the United States Food and Drug Administration.

SUMMARY OF SIGNIFICANT ACCOUN22

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from these estimates.
Cash Equivalents and Marketable Securities	Cash Equivalents and Marketable Securities We consider all highly liquid investments purchased within three months of original maturity date to be cash equivalents. We invest our available cash primarily in commercial paper, money market funds and U.S. Treasury bill funds. We generally classify our marketable securities as available-for-sale at the time of purchase and re-evaluate such designation as of each balance sheet date. The Company classifies its investments as either current or long-term based upon the investments’ contractual maturities and the Company’s ability and intent to convert such instruments to cash within one year. We report available-for-sale investments at fair value as of each balance sheet date and include any unrealized gains and, to the extent deemed temporary, unrealized losses in stockholders’ equity. Realized gains and losses are determined using the specific identification method and are included in other income (expense) in the statement of operations and comprehensive loss. For any of our marketable securities classified as trading securities, changes in the fair value of those securities are recorded as other income (expense) in the statement of operations and comprehensive loss. At December 31, 2015 we had no trading securities. We conduct quarterly reviews to determine the fair value of our investment portfolio and to identify and evaluate each investment that has an unrealized loss, in accordance with the meaning of other-than-temporary impairment and its application to certain investments. An unrealized loss exists when the current fair value of an individual security is less than its amortized cost basis. In the event that the cost basis of a security exceeds its fair value, we evaluate, among other factors, the duration of the period that, and extent to which, the fair value is less than cost basis, the financial health of and business outlook for the issuer, including industry and sector performance, and operational and financing cash flow factors, overall market conditions and trends, our intent to sell the investment and if it is more likely than not that we would be required to sell the investment before its anticipated recovery. Unrealized losses on available-for-sale securities that are determined to be temporary, and not related to credit loss, are recorded in accumulated other comprehensive income (loss). For available-for-sale debt securities with unrealized losses, we perform an analysis to assess whether we intend to sell or whether we would more likely than not be required to sell the security before the expected recovery of the amortized cost basis. Where we intend to sell a security, or may be required to do so, the security’s decline in fair value is deemed to be other-than-temporary and the full amount of the unrealized loss is reflected in the statement of operations and comprehensive loss as an impairment loss. Regardless of our intent to sell a security, we perform additional analysis on all securities with unrealized losses to evaluate losses associated with the creditworthiness of the security. We did not recognize any other-than-temporary impairments during the years ended December 31, 2015, 2014 or 2013. Credit losses are identified where we do not expect to receive cash flows sufficient to recover the amortized cost basis of a security.
Fair Value of Financial Instruments	Fair Value of Financial Instruments At December 31, 2015 and 2014 our financial instruments consist of cash, cash equivalents, investments in corporate debt securities, accounts payable, and accrued expenses. At December 31, 2015 and 2014 our financial instruments also included marketable securities which are reported at fair value.
Non-refundable Advance Payments for Research and Development	Non-refundable Advance Payments for Research and Development Non-refundable advance payments for goods or services that will be used or rendered for future research and development activities are initially deferred and capitalized. Related expenses (or contra-revenues) are then recognized as expense (or contra-revenue) as the goods are delivered and consumed or the related services are performed.
Property and Equipment	Property and Equipment Property and equipment are recorded at cost and depreciated using the straight-line method over their estimated useful lives. Assets under capital leases and leasehold improvements are amortized over the shorter of their estimated useful lives or the term of the respective leases by use of the straight-line method. Maintenance and repair costs are expensed as incurred. Depreciation and amortization expense for the years ended December 31, 2015, 2014 and 2013 was $161, $603, and $864, respectively.
Revenue Recognition-Research and Development Revenue	Revenue Recognition—Research and Development Revenue Research and development revenue is generated primarily through collaborative research and development agreements. The terms of the agreements may include nonrefundable upfront payments, funding for research and development, milestone payments and royalties on any product sales derived from collaborations. The Company adopted the FASB issued ASU No. 2010-17, Revenue Recognition—Milestone Method Research and development payments associated with our collaboration agreements in effect prior to January 1, 2011 are recognized as research and development revenue using the contingency adjusted performance model. Under this model, when payments are earned, revenue is immediately recognized on a pro-rata basis in the period we achieve the milestone based on the time elapsed from inception of the agreement to the time the milestone is earned over the estimated duration of the development period under the agreement. Thereafter, the remaining portion of the milestone payment is recognized on a straight-line basis over the remaining estimated development period under the agreement. This estimated development period may ultimately be shorter or longer depending upon the outcome of the development work, resulting in accelerated or deferred recognition of the development revenue. Royalty payments will be recognized as revenue when earned. The costs associated with satisfying research and development contracts are included in research and development expense as incurred. On November 10, 2011, we and Daiichi Sankyo announced the execution of a license agreement for the development of a new AKT inhibitor, ARQ 092. The license agreement provided exclusive rights to Daiichi Sankyo for the development, manufacturing and marketing of ARQ 092 on a worldwide basis. Following the termination of this agreement, ARQ 092 has become our proprietary asset, and Daiichi Sankyo has no further financial or other obligations or rights related to this program. Revenue for this agreement was recognized using Financial Accounting Standards Board Accounting Standards Update No. 2009-13, Multiple-Deliverable Revenue Arrangements
Research and Development Costs	Research and Development Costs Costs of research and development, which are expensed as incurred, are comprised of the following types of costs incurred in performing research and development activities and those incurred in connection with research and development revenue: salaries and benefits, allocated overhead and occupancy costs, clinical trial and related clinical manufacturing costs, contract services, and other outside costs.
Impairment or Disposal of Long-Lived Assets	Impairment or Disposal of Long-Lived Assets We assess our long-lived assets for impairment whenever events or changes in circumstances (a “triggering event”) indicate that the carrying value of a group of long-lived assets may not be recoverable. If such circumstances are determined to exist, an estimate of undiscounted future cash flows produced by the long-lived asset, including its eventual residual value, is compared to the carrying value to determine whether impairment exists. In the event that such cash flows are not expected to be sufficient to recover the carrying amount of the assets, the assets are written-down to their estimated fair values. As a result of our restructuring in 2014, we recognized an impairment charge related to our long-lived assets of $280. We did not recognize any impairment charges related to our long-lived assets during 2015 or 2013.
Segment Data	Segment Data The chief operating decision maker uses aggregated- financial information in determining how to allocate resources and assess performance. For this reason, we have determined that we are principally engaged in one operating segment. See Note 13 with respect to significant customers. Substantially all of our revenue since inception has been generated in the U.S. and all of our long-lived assets are located in the U.S.
Other Income	Other Income Other income in 2015 includes a gain of  $277 from the sale of property and equipment. Other income in 2014 includes a gain of  $254 upon the redemption of  $2,100 of our remaining auction rate securities at face value, and a gain of  $388 from the sale of property and equipment. Other income in 2013 a gain from the increase in fair value of our auction rate securities of  $57.
Income Taxes	Income Taxes Income taxes have been accounted for using the asset and liability method. Under the asset and liability method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance against deferred tax assets is recorded if, based upon the weight of all available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. For uncertain tax positions that meet “a more likely than not” threshold, the Company recognizes the benefit of uncertain tax positions in the financial statements.
Earnings (Loss) Per Share	Earnings (Loss) Per Share The computations of basic and diluted earnings (loss) per common share are based upon the weighted average number of common shares outstanding and potentially dilutive securities. Potentially dilutive securities include stock options. Options to purchase 8,305,950, 7,724,614 and 7,511,814 shares of common stock were not included in the 2015, 2014 and 2013 computations of diluted net loss per share, respectively, because inclusion of such shares would have an anti-dilutive effect.
Stock-Based Compensation	Stock-Based Compensation Our stock-based compensation cost is measured at the grant date, based on the calculated fair value of the award, and is recognized as an expense over the employees’ requisite service period (generally the vesting period of the equity grant). We estimate the fair value of stock options using the Black-Scholes valuation model. Key input assumptions used to estimate the fair value of stock options include the exercise price of the award, expected option term, expected volatility of our stock over the option’s expected term, risk-free interest rate over the option’s expected term, and the expected annual dividend yield. We believe that the valuation technique and approach utilized to develop the underlying assumptions are appropriate in calculating the fair values of our stock options granted. The following table presents stock-based compensation expense for the years ended December 31, 2015, 2014 and 2013 included in our Statements of Operations and Comprehensive Loss: ​ ​ ​ 2015 ​ ​ 2014 ​ ​ 2013 ​ Research and development ​ ​ ​ $ 682 ​ ​ ​ ​ $ 1,016 ​ ​ ​ ​ $ 1,315 ​ ​ General and administrative ​ ​ ​ ​ 1,579 ​ ​ ​ ​ ​ 2,183 ​ ​ ​ ​ ​ 2,489 ​ ​ Restructuring ​ ​ ​ ​ — ​ ​ ​ ​ ​ 83 ​ ​ ​ ​ ​ 139 ​ ​ Total stock-based compensation expense ​ ​ ​ $ 2,261 ​ ​ ​ ​ $ 3,282 ​ ​ ​ ​ $ 3,943 ​ ​ ​ In the years ended December 31, 2015, 2014 and 2013, no stock-based compensation expense was capitalized and there were no recognized tax benefits associated with the stock-based compensation charges. The fair value of stock options and employee stock purchase plan shares granted in the years ended December 31, 2015, 2014 and 2013 respectively were estimated on the grant date using the Black-Scholes option-pricing model with the following assumptions: ​ ​ ​ 2015 ​ ​ 2014 ​ ​ 2013 ​ Dividend yield(1) ​ ​ 0.0%​ ​ ​ 0.0%​ ​ ​ 0.0%​ ​ Weighted average expected volatility factor(2) ​ ​ 66%​ ​ ​ 67%​ ​ ​ 73%​ ​ Risk free interest(3) ​ ​ 1.3–1.7%​ ​ ​ 1.5–1.8%​ ​ ​ 0.8–1.7%​ ​ Expected term, excluding options issued pursuant to the Employee Stock Purchase Plan(4) ​ ​ 5.6–6.8 years​ ​ ​ 5.8–6.9 years​ ​ ​ 5.9–7.1 years​ ​ Expected term—Employee Stock Purchase Plan(5) ​ ​ 6 months​ ​ ​ 6 months​ ​ ​ 6 months​ ​ ​ (1) We have historically not paid dividends on our common stock and we do not anticipate paying any dividends in the foreseeable future. ​ (2) Measured using an average of historical daily price changes of our stock over a period equal to our expected term. ​ (3) The risk-free interest rate for periods equal to the expected term of share option based on the U.S. Treasury yield in effect at the time of grant. ​ (4) The expected term is the number of years that we estimate, based on historical experience, that options will be outstanding before exercise or cancellation. The range in expected term is the result of certain groups of employees exhibiting different exercising behavior. ​ (5) The expected term of options issued in connection with our Employee Stock Purchase Plan is 6 months based on the terms of the plan.
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, we believe that the impact of recently issued standards that are not yet effective will not have a material impact on our financial position or results of operations upon adoption. In August 2014, the FASB issued Accounting Standard Update (“ASU”) 2014-15, Presentation of Financial Statements—Going Concern (Subtopic 205-40): Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern. Under the new guidance, management will be required to assess an entity’s ability to continue as a going concern, and to provide related footnote disclosures in certain circumstances. The provisions of this ASU are effective for annual periods beginning after December 15, 2016, and for annual and interim periods thereafter. We are currently evaluating the potential impact that this ASU may have on our disclosures. In June 2014, the FASB issued ASU No. 2014-12, “Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved after the Requisite Service Period.” This ASU requires a reporting entity to treat a performance target that affects vesting and that could be achieved after the requisite service period as a performance condition, and apply existing guidance under the Stock Compensation Topic of the ASC as it relates to awards with performance conditions that affect vesting to account for such awards. The provisions of this ASU are effective for interim and annual periods beginning after December 15, 2015. We are currently evaluating the potential impact that this ASU may have on our financial position and results of operations. During the quarter ended June 30, 2014, the FASB issued ASU No. 2014-09, “Revenue from Contracts with Customers” (Topic 606), which supersedes all existing revenue recognition requirements, including most industry-specific guidance. The new standard requires a company to recognize revenue when it transfers goods or services to customers in an amount that reflects the consideration that the company expects to receive for those goods or services. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date, which delayed the effective date of the new standard from January 1, 2017 to January 1, 2018. The FASB also agreed to allow entities to choose to adopt the standard as of the original effective date. We are currently evaluating the method of adoption and the potential impact that Topic 606 may have on our financial position and results of operations.

SUMMARY OF SIGNIFICANT ACCOUN23

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Schedule of stock-based compensation expense	​ ​ ​ 2015 ​ ​ 2014 ​ ​ 2013 ​ Research and development ​ ​ ​ $ 682 ​ ​ ​ ​ $ 1,016 ​ ​ ​ ​ $ 1,315 ​ ​ General and administrative ​ ​ ​ ​ 1,579 ​ ​ ​ ​ ​ 2,183 ​ ​ ​ ​ ​ 2,489 ​ ​ Restructuring ​ ​ ​ ​ — ​ ​ ​ ​ ​ 83 ​ ​ ​ ​ ​ 139 ​ ​ Total stock-based compensation expense ​ ​ ​ $ 2,261 ​ ​ ​ ​ $ 3,282 ​ ​ ​ ​ $ 3,943 ​ ​ ​
Schedule of fair value under the Black-Scholes model	​ ​ ​ 2015 ​ ​ 2014 ​ ​ 2013 ​ Dividend yield(1) ​ ​ 0.0%​ ​ ​ 0.0%​ ​ ​ 0.0%​ ​ Weighted average expected volatility factor(2) ​ ​ 66%​ ​ ​ 67%​ ​ ​ 73%​ ​ Risk free interest(3) ​ ​ 1.3–1.7%​ ​ ​ 1.5–1.8%​ ​ ​ 0.8–1.7%​ ​ Expected term, excluding options issued pursuant to the Employee Stock Purchase Plan(4) ​ ​ 5.6–6.8 years​ ​ ​ 5.8–6.9 years​ ​ ​ 5.9–7.1 years​ ​ Expected term—Employee Stock Purchase Plan(5) ​ ​ 6 months​ ​ ​ 6 months​ ​ ​ 6 months​ ​ ​ (1) We have historically not paid dividends on our common stock and we do not anticipate paying any dividends in the foreseeable future. ​ (2) Measured using an average of historical daily price changes of our stock over a period equal to our expected term. ​ (3) The risk-free interest rate for periods equal to the expected term of share option based on the U.S. Treasury yield in effect at the time of grant. ​ (4) The expected term is the number of years that we estimate, based on historical experience, that options will be outstanding before exercise or cancellation. The range in expected term is the result of certain groups of employees exhibiting different exercising behavior. ​ (5) The expected term of options issued in connection with our Employee Stock Purchase Plan is 6 months based on the terms of the plan.

MARKETABLE SECURITIES AND FAI24

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2015
Marketable Securities and Fair Value Measurements [Abstract]
Schedule of fair value of available-for-sale marketable securities	December 31, 2015 ​ ​ Amortized Cost ​ ​ Gross Gains ​ ​ Gross Losses ​ ​ Fair Value ​ Security type ​ ​ ​ ​ ​ Corporate debt securities-short term ​ ​ ​ $ 24,786 ​ ​ ​ ​ $ 13 ​ ​ ​ ​ $ (10 ) ​ ​ ​ ​ $ 24,789 ​ ​ Corporate debt securities-long term ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Total available-for-sale marketable securities ​ ​ ​ $ 24,786 ​ ​ ​ ​ $ 13 ​ ​ ​ ​ $ (10 ) ​ ​ ​ ​ $ 24,789 ​ ​ ​ December 31, 2014 ​ ​ Amortized Cost ​ ​ Gross Gains ​ ​ Gross Losses ​ ​ Fair Value ​ Security type ​ ​ ​ ​ ​ Corporate debt securities-short term ​ ​ ​ $ 46,690 ​ ​ ​ ​ $ 16 ​ ​ ​ ​ $ (23 ) ​ ​ ​ ​ $ 46,683 ​ ​ Corporate debt securities-long term ​ ​ ​ ​ 2,061 ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ (3 ) ​ ​ ​ ​ ​ 2,058 ​ ​ Total available-for-sale marketable securities ​ ​ ​ $ 48,751 ​ ​ ​ ​ $ 16 ​ ​ ​ ​ $ (26 ) ​ ​ ​ ​ $ 48,741 ​ ​
Schedule of assets measured at fair value on a recurring basis	​ December 31, ​ ​ Quoted Prices in ​ ​ Significant ​ ​ Significant ​ Cash equivalents ​ ​ ​ $ 11,800 ​ ​ ​ ​ $ 11,800 ​ ​ ​ ​ $ — ​ ​ ​ ​ $ — ​ ​ Corporate debt securities-short term ​ ​ ​ ​ 24,789 ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ 24,789 ​ ​ ​ ​ ​ — ​ ​ Corporate debt securities-long term ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Total ​ ​ ​ $ 36,589 ​ ​ ​ ​ $ 11,800 ​ ​ ​ ​ $ 24,789 ​ ​ ​ ​ $ — ​ ​ ​ ​ ​ ​ December 31, ​ ​ Quoted Prices in ​ ​ Significant ​ ​ Significant ​ Cash equivalents ​ ​ ​ $ 10,740 ​ ​ ​ ​ $ 10,740 ​ ​ ​ ​ $ — ​ ​ ​ ​ $ — ​ ​ Corporate debt securities-short term ​ ​ ​ ​ 46,683 ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ 46,683 ​ ​ ​ ​ ​ — ​ ​ Corporate debt securities-long term ​ ​ ​ ​ 2,058 ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ 2,058 ​ ​ ​ ​ ​ — ​ ​ Total ​ ​ ​ $ 59,481 ​ ​ ​ ​ $ 10,740 ​ ​ ​ ​ $ 48,741 ​ ​ ​ ​ $ — ​ ​ ​

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Schedule of property and equipment	​ ​ ​ USEFUL ​ ​ 2015 ​ ​ 2014 ​ Machinery and equipment ​ ​ 5​ ​ ​ ​ $ 1,939 ​ ​ ​ ​ $ 2,562 ​ ​ Leasehold improvements ​ ​ 3–10​ ​ ​ ​ ​ 232 ​ ​ ​ ​ ​ 1,005 ​ ​ Furniture and fixtures ​ ​ 7​ ​ ​ ​ ​ 40 ​ ​ ​ ​ ​ 1,175 ​ ​ Computer equipment ​ ​ 3​ ​ ​ ​ ​ 2,482 ​ ​ ​ ​ ​ 3,604 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 4,693 ​ ​ ​ ​ ​ 8,346 ​ ​ Less: Accumulated depreciation and amortization ​ ​ ​ ​ ​ ​ ​ 4,427 ​ ​ ​ ​ ​ 8,213 ​ ​ Net property and equipment ​ ​ ​ ​ ​ ​ $ 266 ​ ​ ​ ​ $ 133 ​ ​ ​

OTHER ASSETS (Tables)

OTHER ASSETS (Tables)	12 Months Ended
	Dec. 31, 2015
Other Assets [Abstract]
Schedule of other assets	​ ​ ​ 2015 ​ ​ 2014 ​ Security deposits ​ ​ ​ $ 252 ​ ​ ​ ​ $ 102 ​ ​ Total other assets ​ ​ ​ $ 252 ​ ​ ​ ​ $ 102 ​ ​ ​

ACCOUNTS PAYABLE AND ACCRUED 27

ACCOUNTS PAYABLE AND ACCRUED EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2015
Payables and Accruals [Abstract]
Schedule of accounts payable and accrued expense	​ ​ ​ 2015 ​ ​ 2014 ​ Accounts payable ​ ​ ​ $ 186 ​ ​ ​ ​ $ 259 ​ ​ Accrued payroll ​ ​ ​ ​ 1,956 ​ ​ ​ ​ ​ 2,130 ​ ​ Accrued outsourced pre-clinical and clinical fees ​ ​ ​ ​ 3,273 ​ ​ ​ ​ ​ 3,753 ​ ​ Accrued professional fees ​ ​ ​ ​ 516 ​ ​ ​ ​ ​ 157 ​ ​ Other accrued expenses ​ ​ ​ ​ 303 ​ ​ ​ ​ ​ 648 ​ ​ ​ ​ ​ ​ $ 6,234 ​ ​ ​ ​ $ 6,947 ​ ​ ​

EQUITY INCENTIVE PLANS (Tables)

EQUITY INCENTIVE PLANS (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure Of Compensation Related Costs, Share-Based Payments [Abstract]
Schedule of activity of options under stock plans	Stock Options ​ ​ Number of Shares ​ ​ Weighted Average Exercise Price ​ Outstanding as of December 31, 2012 ​ ​ ​ ​ 7,157,458 ​ ​ ​ ​ $ 5.70 ​ ​ Granted ​ ​ ​ ​ 1,220,910 ​ ​ ​ ​ ​ 2.53 ​ ​ Exercised ​ ​ ​ ​ (3,000 ) ​ ​ ​ ​ ​ 2.35 ​ ​ Cancelled ​ ​ ​ ​ (863,554 ) ​ ​ ​ ​ ​ 4.82 ​ ​ Outstanding as of December 31, 2013 ​ ​ ​ ​ 7,511,814 ​ ​ ​ ​ $ 5.28 ​ ​ Granted ​ ​ ​ ​ 1,150,119 ​ ​ ​ ​ ​ 2.47 ​ ​ Exercised ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Cancelled ​ ​ ​ ​ (937,319 ) ​ ​ ​ ​ ​ 5.06 ​ ​ Outstanding as of December 31, 2014 ​ ​ ​ ​ 7,724,614 ​ ​ ​ ​ $ 4.89 ​ ​ Granted ​ ​ ​ ​ 1,513,850 ​ ​ ​ ​ ​ 1.25 ​ ​ Exercised ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Cancelled ​ ​ ​ ​ (932,514 ) ​ ​ ​ ​ ​ 4.82 ​ ​ Outstanding as of December 31, 2015 ​ ​ ​ ​ 8,305,950 ​ ​ ​ ​ $ 4.24 ​ ​ Exercisable as of December 31, 2015 ​ ​ ​ ​ 5,756,625 ​ ​ ​ ​ $ 5.12 ​ ​ ​
Schedule of options outstanding	​ ​ ​ Options Outstanding ​ ​ Options Exercisable ​ Range of Exercise Prices ​ ​ Number December 31, 2015 ​ ​ Weighted Average Contractual Life ​ ​ Weighted Average Exercise Price ​ ​ Exercisable as of December 31, 2015 ​ ​ Weighted Average Exercise Price ​ $1.16–1.42 ​ ​ ​ ​ 1,206,350 ​ ​ ​ ​ ​ 9.01 ​ ​ ​ ​ $ 1.17 ​ ​ ​ ​ ​ 7,800 ​ ​ ​ ​ $ 1.16 ​ ​  1.43–2.35 ​ ​ ​ ​ 318,750 ​ ​ ​ ​ ​ 8.98 ​ ​ ​ ​ ​ 1.70 ​ ​ ​ ​ ​ 105,000 ​ ​ ​ ​ ​ 1.46 ​ ​  2.36–2.80 ​ ​ ​ ​ 1,756,703 ​ ​ ​ ​ ​ 6.94 ​ ​ ​ ​ ​ 2.55 ​ ​ ​ ​ ​ 815,072 ​ ​ ​ ​ ​ 2.56 ​ ​  2.81–5.60 ​ ​ ​ ​ 2,053,809 ​ ​ ​ ​ ​ 2.87 ​ ​ ​ ​ ​ 3.89 ​ ​ ​ ​ ​ 2,053,809 ​ ​ ​ ​ ​ 3.89 ​ ​  5.61–8.40 ​ ​ ​ ​ 2,893,338 ​ ​ ​ ​ ​ 3.92 ​ ​ ​ ​ ​ 6.93 ​ ​ ​ ​ ​ 2,697,944 ​ ​ ​ ​ ​ 6.86 ​ ​  8.41–9.45 ​ ​ ​ ​ 77,000 ​ ​ ​ ​ ​ 1.37 ​ ​ ​ ​ ​ 9.09 ​ ​ ​ ​ ​ 77,000 ​ ​ ​ ​ ​ 9.09 ​ ​ ​ ​ ​ ​ ​ 8,305,950 ​ ​ ​ ​ ​ 5.21 ​ ​ ​ ​ $ 4.24 ​ ​ ​ ​ ​ 5,756,625 ​ ​ ​ ​ $ 5.12 ​ ​ ​
Schedule of shares vested, expected to vest and exercisable	​ ​ ​ Options ​ ​ Weighted-Average ​ ​ Weighted-Average ​ ​ Aggregate ​ Vested and unvested expected to vest at December 31, 2015 ​ ​ ​ ​ 8,119,246 ​ ​ ​ ​ $ 4.24 ​ ​ ​ ​ ​ 5.21 ​ ​ ​ ​ $ 1,265 ​ ​ Exercisable at December 31, 2015 ​ ​ ​ ​ 5,756,625 ​ ​ ​ ​ $ 5.12 ​ ​ ​ ​ ​ 3.82 ​ ​ ​ ​ $ 83 ​ ​
Schedule of restricted stock activity	Restricted Stock ​ ​ Number of Shares ​ ​ Weighted Average Fair Value ​ Unvested as of December 31, 2014 ​ ​ ​ ​ 105,665 ​ ​ ​ ​ $ 2.51 ​ ​ Granted ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Vested ​ ​ ​ ​ (36,101 ) ​ ​ ​ ​ ​ 2.51 ​ ​ Cancelled ​ ​ ​ ​ (10,929 ) ​ ​ ​ ​ ​ 2.51 ​ ​ Unvested as of December 31, 2015 ​ ​ ​ ​ 58,635 ​ ​ ​ ​ $ 2.51 ​ ​ ​

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of company's effective income tax rate	​ ​ ​ 2015 ​ ​ 2014 ​ ​ 2013 ​ Income tax (benefit) expense at statutory rate ​ ​ ​ $ (4,683 ) ​ ​ ​ ​ $ (7,953 ) ​ ​ ​ ​ $ (8,364 ) ​ ​ State tax (benefit) expense, net of Federal tax (benefit) expense ​ ​ ​ ​ (677 ) ​ ​ ​ ​ ​ (1,154 ) ​ ​ ​ ​ ​ (901 ) ​ ​ Permanent items ​ ​ ​ ​ 239 ​ ​ ​ ​ ​ 383 ​ ​ ​ ​ ​ 516 ​ ​ Effect of change in valuation allowance and State NOL expiration ​ ​ ​ ​ 4,945 ​ ​ ​ ​ ​ 9,402 ​ ​ ​ ​ ​ 10,862 ​ ​ Tax credits ​ ​ ​ ​ (74 ) ​ ​ ​ ​ ​ (678 ) ​ ​ ​ ​ ​ (2,113 ) ​ ​ Other ​ ​ ​ ​ 250 ​ ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Tax expense (benefit) ​ ​ ​ $ — ​ ​ ​ ​ $ — ​ ​ ​ ​ $ — ​ ​ ​
Schedule of company's deferred tax assets and liabilities	​ ​ ​ 2015 ​ ​ 2014 ​ Deferred tax assets: ​ ​ ​ Net operating loss carryforwards ​ ​ ​ $ 125,599 ​ ​ ​ ​ $ 115,747 ​ ​ Tax credit carryforwards ​ ​ ​ ​ 25,036 ​ ​ ​ ​ ​ 24,962 ​ ​ Equity based compensation ​ ​ ​ ​ 9,176 ​ ​ ​ ​ ​ 8,558 ​ ​ Book depreciation in excess of tax ​ ​ ​ ​ 35 ​ ​ ​ ​ ​ 1,352 ​ ​ Reserves and accruals ​ ​ ​ ​ 276 ​ ​ ​ ​ ​ 52 ​ ​ Deferred revenue ​ ​ ​ ​ 1,796 ​ ​ ​ ​ ​ 6,115 ​ ​ Loss on investment ​ ​ ​ ​ — ​ ​ ​ ​ ​ 194 ​ ​ Other ​ ​ ​ ​ 26 ​ ​ ​ ​ ​ 19 ​ ​ ​ ​ ​ ​ ​ 161,944 ​ ​ ​ ​ ​ 156,999 ​ ​ Valuation allowance ​ ​ ​ ​ (161,944 ) ​ ​ ​ ​ ​ (156,999 ) ​ ​ Deferred tax liabilities ​ ​ ​ ​ — ​ ​ ​ ​ ​ — ​ ​ Net deferred tax assets ​ ​ ​ $ — ​ ​ ​ ​ $ — ​ ​ ​

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of future minimum lease payments under non-cancelable operating leases	YEAR ENDING DECEMBER 31, ​ ​ OPERATING LEASES ​ 2016 ​ ​ ​ $ 529 ​ ​ 2017 ​ ​ ​ ​ 488 ​ ​ 2018 ​ ​ ​ ​ 484 ​ ​ 2019 ​ ​ ​ ​ 499 ​ ​ Thereafter ​ ​ ​ ​ 296 ​ ​ Total minimum lease payments ​ ​ ​ $ 2,296 ​ ​ ​

SELECTED QUARTERLY FINANCIAL 31

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of unaudited quarterly financial data	​ ​ ​ FIRST ​ ​ SECOND ​ ​ THIRD ​ ​ FOURTH ​ 2015 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net revenues ​ ​ ​ $ 2,785 ​ ​ ​ ​ $ 3,004 ​ ​ ​ ​ $ 2,653 ​ ​ ​ ​ $ 2,797 ​ ​ Net loss ​ ​ ​ ​ (4,551 ) ​ ​ ​ ​ ​ (4,017 ) ​ ​ ​ ​ ​ (2,354 ) ​ ​ ​ ​ ​ (2,852 ) ​ ​ Basic and diluted net loss per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share ​ ​ ​ $ (0.07 ) ​ ​ ​ ​ $ (0.06 ) ​ ​ ​ ​ $ (0.04 ) ​ ​ ​ ​ $ (0.05 ) ​ ​ ​ ​ ​ FIRST ​ ​ SECOND ​ ​ THIRD ​ ​ FOURTH ​ 2014 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net revenues ​ ​ ​ $ 2,676 ​ ​ ​ ​ $ 2,901 ​ ​ ​ ​ $ 2,662 ​ ​ ​ ​ $ 3,015 ​ ​ Net loss ​ ​ ​ ​ (7,141 ) ​ ​ ​ ​ ​ (6,339 ) ​ ​ ​ ​ ​ (6,399 ) ​ ​ ​ ​ ​ (3,512 ) ​ ​ Basic and diluted earnings (loss) per share: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Net loss per share ​ ​ ​ $ (0.11 ) ​ ​ ​ ​ $ (0.10 ) ​ ​ ​ ​ $ (0.10 ) ​ ​ ​ ​ $ (0.06 ) ​ ​

ORGANIZATION AND NATURE OF OP32

ORGANIZATION AND NATURE OF OPERATIONS (Detail Textuals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Net use of cash	$ (22,160)	$ (31,782)	$ (33,680)
Kyowa Hakko Kirin Co. Ltd. | License agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront and milestone payments received	48,000
Daiichi Sankyo Co. Ltd | License agreement
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront and milestone payments received	100,000
Upfront and milestone payment received related to Metiv-HccTrial	$ 15,000

SUMMARY OF SIGNIFICANT ACCOUN33

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Stock-based compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 2,261	$ 3,282	$ 3,943
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	682	1,016	1,315
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,579	2,183	2,489
Restructuring
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense		$ 83	$ 139

SUMMARY OF SIGNIFICANT ACCOUN34

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - The fair value of stock options and employee stock purchase plan shares Valuaton assumptions (Details 1) - Stock Options		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	[1]	5 years 7 months 6 days	5 years 9 months 18 days	5 years 10 months 24 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	[1]	6 years 9 months 18 days	6 years 10 months 24 days	7 years 1 month 6 days
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	[2]	0.00%	0.00%	0.00%
Weighted average expected volatility factor	[3]	66.00%	67.00%	73.00%
Expected term	[4]	6 months	6 months	6 months
Employee stock purchase plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest	[5]	1.30%	1.50%	0.80%
Employee stock purchase plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest	[5]	1.70%	1.80%	1.70%
[1]	The expected term is the number of years that we estimate, based on historical experience, that options will be outstanding before exercise or cancellation. The range in expected term is the result of certain groups of employees exhibiting different exercising behavior.
[2]	We have historically not paid dividends on our common stock and we do not anticipate paying any dividends in the foreseeable future.
[3]	Measured using an average of historical daily price changes of our stock over a period equal to our expected term.
[4]	The expected term of options issued in connection with our Employee Stock Purchase Plan is 6 months based on the terms of the plan.
[5]	The risk-free interest rate for periods equal to the expected term of share option based on the U.S. Treasury yield in effect at the time of grant.

SUMMARY OF SIGNIFICANT ACCOUN35

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Detail Textuals) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)Segment	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Accounting Policies [Abstract]
Depreciation method	Straight-line method
Depreciation and amortization expense	$ 161	$ 603	$ 864
Impairment of property and equipment		280
Number of operating segments | Segment	1
Gain on auction rate securities		254	$ 57
Redemption of auction rate security		2,100
Gain on sale of propert plant and equipment	$ 277	$ 388
Fair value valuation method	Black-Scholes option-pricing model

SUMMARY OF SIGNIFICANT ACCOUN36

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Detail Textuals 1) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares of common stock not included in computations of diluted net loss per share	8,305,950	7,724,614	7,511,814

COLLABORATIONS AND ALLIANCES (D

COLLABORATIONS AND ALLIANCES (Detail Textuals) - Daiichi Sankyo Tivantinib Agreement - USD ($) $ in Millions	Nov. 03, 2015	Dec. 31, 2008	Jan. 31, 2013	Feb. 28, 2011	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Upfront payment received		$ 60
Additional potential development and sales milestone payments		$ 560
Milestone payments to be received upon acceptance of drug approval applications for HCC	$ 55
Milestone payments to be received upon regulatory approvals and first commercial sales in HCC	$ 100
Baseline contractual rate	20.00%
Net research and development revenue					$ 5.5	$ 5.6	$ 7.2
Contra revenue recognized					0.1	0.2	$ 0.7
Notice period for termination of contract prior to start of specified period							90 days
Notice period for termination of contract Post start of Phase 3 clinical trials							180 days
Deferred revenue					2.7	8.1
Phase 3 collaboration costs
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Cumulative share of phase 3 collaboration costs					101.4
Milestone payment received			$ 15	$ 25
Total milestone partially offset	$ 155
Cumulative share of phase 3 collaboration costs in excess of milestones amounts received					61.4
Non-Phase 3 tivantinib collaboration costs
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Net research and development revenue					0.1	0.2	$ 0.4
Revenue included in research and development revenue					0.2	0.4	0.3
Contra revenue included in research and development revenue					$ 0.1	$ 0.2	$ 0.7

COLLABORATIONS AND ALLIANCES 38

COLLABORATIONS AND ALLIANCES (Detail Textuals 1) - USD ($) $ in Thousands

May. 07, 2007

Aug. 31, 2011

Sep. 30, 2010

Feb. 29, 2008

Apr. 27, 2007

Dec. 31, 2015

Sep. 30, 2015

Jun. 30, 2015

Mar. 31, 2015

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Mar. 31, 2007

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

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

Research and development revenue

$ 2,797

$ 2,653

$ 3,004

$ 2,785

$ 3,015

$ 2,662

$ 2,901

$ 2,676

$ 11,239

$ 11,254

$ 15,914

Kyowa Hakko Kirin Licensing Agreement

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

Upfront payment received

$ 27,000

$ 3,000

Upfront and potential development milestone payments

$ 123,000

Cash upfront licensing payments - total to date

$ 30,000

Notice period for termination of contract

90 days

Research and development revenue

$ 5,700

5,700

$ 5,700

Deferred revenue

$ 1,900

$ 7,600

$ 1,900

$ 7,600

Kyowa Hakko Kirin Licensing Agreement | Phase Two trial Kyowa Hakko Kirin

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

Milestone payment received

$ 5,000

Kyowa Hakko Kirin Licensing Agreement | Phase Three Attention Trial Asia

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

Milestone payment received

$ 10,000

Kyowa Hakko Kirin Licensing Agreement | Kyowa Hakko Kirin

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

Milestone payment received

$ 3,000

Percentage of royalties expected to be received - lower range

mid-teen percent

Percentage of royalties expected to be received - upper range

low-twenty percent

MARKETABLE SECURITIES AND FAI39

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS - Summary of fair value of available-for-sale securities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 24,786	$ 48,751
Gross Unrealized Gains	13	16
Gross Unrealized Losses	(10)	(26)
Fair Value	24,789	48,741
Corporate debt securities | Short term
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	24,786	46,690
Gross Unrealized Gains	13	16
Gross Unrealized Losses	(10)	(23)
Fair Value	$ 24,789	46,683
Corporate debt securities | Long term
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		$ 2,061
Gross Unrealized Gains
Gross Unrealized Losses		$ (3)
Fair Value		$ 2,058

MARKETABLE SECURITIES AND FAI40

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS - Assets measured at fair value on a recurring basis (Details 1) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities-short term & long term	$ 24,789	$ 48,741
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	11,800	10,740
Total	36,589	59,481
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	11,800	10,740
Total	$ 11,800	$ 10,740
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents
Total	$ 24,789	$ 48,741
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents
Total
Fair Value, Measurements, Recurring | Corporate debt securities | Short term
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities-short term & long term	$ 24,789	$ 46,683
Fair Value, Measurements, Recurring | Corporate debt securities | Long term
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities-short term & long term		$ 2,058
Fair Value, Measurements, Recurring | Corporate debt securities | Quoted Prices in Active Markets (Level 1) | Short term
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities-short term & long term
Fair Value, Measurements, Recurring | Corporate debt securities | Quoted Prices in Active Markets (Level 1) | Long term
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities-short term & long term
Fair Value, Measurements, Recurring | Corporate debt securities | Significant Other Observable Inputs (Level 2) | Short term
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities-short term & long term	$ 24,789	$ 46,683
Fair Value, Measurements, Recurring | Corporate debt securities | Significant Other Observable Inputs (Level 2) | Long term
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities-short term & long term		$ 2,058
Fair Value, Measurements, Recurring | Corporate debt securities | Significant Unobservable Inputs (Level 3) | Short term
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities-short term & long term
Fair Value, Measurements, Recurring | Corporate debt securities | Significant Unobservable Inputs (Level 3) | Long term
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Corporate debt securities-short term & long term

MARKETABLE SECURITIES AND FAI41

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS (Detail Textuals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Marketable Securities and Fair Value Measurements [Abstract]
Redemption of auction rate security	$ 2.1
Investment in auction rate securities, at cost		$ 2.1

PROPERTY AND EQUIPMENT - Proper

PROPERTY AND EQUIPMENT - Property and equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4,693	$ 8,346
Less: Accumulated depreciation and amortization	4,427	8,213
Net property and equipment	$ 266	133
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Estimated Useful Life (Years)	5 years
Property and equipment, gross	$ 1,939	2,562
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 232	1,005
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
Property and equipment, Estimated Useful Life (Years)	3 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
Property and equipment, Estimated Useful Life (Years)	10 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, Estimated Useful Life (Years)	7 years
Property and equipment, gross	$ 40	1,175
Computer equipment
Property, Plant and Equipment [Line Items]
Property and equipment, Estimated Useful Life (Years)	3 years
Property and equipment, gross	$ 2,482	$ 3,604

PROPERTY AND EQUIPMENT (Detail

PROPERTY AND EQUIPMENT (Detail Textuals) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2015USD ($)ft²	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Property, Plant and Equipment [Line Items]
Impairment of property and equipment			$ 280
Gain on sale of propert plant and equipment		$ 277	388
Property and equipment original cost		4,000	10,400
Property and equipment accumulated depreciation		$ 4,000	$ 10,300
Lease Agreement
Property, Plant and Equipment [Line Items]
Area of Land | ft²	15,000
Lease term	5 years 3 months
Lease average annual rental rate amount	$ 455

OTHER ASSETS - Components of Ot

OTHER ASSETS - Components of Other assets (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Other Assets, Noncurrent [Abstract]
Security deposits	$ 252	$ 102
Total other assets	$ 252	$ 102

ACCOUNTS PAYABLE AND ACCRUED 45

ACCOUNTS PAYABLE AND ACCRUED EXPENSES - Summary of accounts payable and accrued expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Payables and Accruals [Abstract]
Accounts payable	$ 186	$ 259
Accrued payroll	1,956	2,130
Accrued outsourced pre-clinical and clinical fees	3,273	3,753
Accrued professional fees	516	157
Other accrued expenses	303	648
Accounts payable and accrued expenses, Total	$ 6,234	$ 6,947

STOCKHOLDERS' EQUITY (Detail Te

STOCKHOLDERS' EQUITY (Detail Textuals) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Class of Stock [Line Items]
Preferred stock, shares authorized	1,000,000	1,000,000
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Employee Stock Purchase Plan ("Purchase Plan") | Common Stock
Class of Stock [Line Items]
Common shares reserved for future issuance under the employee stock purchase plan	253,460
2014 Equity Incentives Plan ("Equity Incentives Plan") , the Amended and Restated 1994 Equity Incentive Plan and the Amended and Restated 1996 Director Stock Option Plan ("Director Plan")
Class of Stock [Line Items]
Exercise of common stock options	4,311,474

EQUITY INCENTIVE PLANS - Option

EQUITY INCENTIVE PLANS - Option activity (Details) - Equity Incentive Plan - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Number of Shares
Outstanding	7,724,614	7,511,814	7,157,458
Granted	1,513,850	1,150,119	1,220,910
Exercised			(3,000)
Cancelled	(932,514)	(937,319)	(863,554)
Outstanding	8,305,950	7,724,614	7,511,814
Exercisable	5,756,625
Weighted Average Exercise Price
Outstanding	$ 4.89	$ 5.28	$ 5.70
Granted	$ 1.25	$ 2.47	2.53
Exercised			2.35
Cancelled	$ 4.82	$ 5.06	4.82
Outstanding	4.24	$ 4.89	$ 5.28
Exercisable	$ 5.12

EQUITY INCENTIVE PLANS - Summar

EQUITY INCENTIVE PLANS - Summary of options outstanding (Details 1) - Equity Incentive Plan - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2015	8,305,950	7,724,614	7,511,814	7,157,458
Options Outstanding, Weighted Average Remaining Contractual Life	5 years 2 months 16 days
Options Outstanding, Weighted Average Exercise Price	$ 4.24	$ 4.89	$ 5.28	$ 5.70
Options Exercisable as of December 31, 2015	5,756,625
Options Exercisable, Weighted Average Exercise Price	$ 5.12
Range of Exercise Prices : $ 1.16 - 1.42
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2015	1,206,350
Options Outstanding, Weighted Average Remaining Contractual Life	9 years 4 days
Options Outstanding, Weighted Average Exercise Price	$ 1.17
Options Exercisable as of December 31, 2015	7,800
Options Exercisable, Weighted Average Exercise Price	$ 1.16
Range of Exercise Prices, Lower Limit	1.16
Range of Exercise Prices, Upper Limit	$ 1.42
Range of Exercise Prices : $ 1.43 - 2.35
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2015	318,750
Options Outstanding, Weighted Average Remaining Contractual Life	8 years 11 months 23 days
Options Outstanding, Weighted Average Exercise Price	$ 1.70
Options Exercisable as of December 31, 2015	105,000
Options Exercisable, Weighted Average Exercise Price	$ 1.46
Range of Exercise Prices, Lower Limit	1.43
Range of Exercise Prices, Upper Limit	$ 2.35
Range of Exercise Prices : $ 2.36 - 2.80
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2015	1,756,703
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 11 months 9 days
Options Outstanding, Weighted Average Exercise Price	$ 2.55
Options Exercisable as of December 31, 2015	815,072
Options Exercisable, Weighted Average Exercise Price	$ 2.56
Range of Exercise Prices, Lower Limit	2.36
Range of Exercise Prices, Upper Limit	$ 2.80
Range of Exercise Prices : $ 2.81 - 5.60
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2015	2,053,809
Options Outstanding, Weighted Average Remaining Contractual Life	2 years 10 months 13 days
Options Outstanding, Weighted Average Exercise Price	$ 3.89
Options Exercisable as of December 31, 2015	2,053,809
Options Exercisable, Weighted Average Exercise Price	$ 3.89
Range of Exercise Prices, Lower Limit	2.81
Range of Exercise Prices, Upper Limit	$ 5.60
Range of Exercise Prices : $ 5.61 - 8.40
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2015	2,893,338
Options Outstanding, Weighted Average Remaining Contractual Life	3 years 11 months 1 day
Options Outstanding, Weighted Average Exercise Price	$ 6.93
Options Exercisable as of December 31, 2015	2,697,944
Options Exercisable, Weighted Average Exercise Price	$ 6.86
Range of Exercise Prices, Lower Limit	5.61
Range of Exercise Prices, Upper Limit	$ 8.40
Range of Exercise Prices : $ 8.41- 9.45
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2015	77,000
Options Outstanding, Weighted Average Remaining Contractual Life	1 year 4 months 13 days
Options Outstanding, Weighted Average Exercise Price	$ 9.09
Options Exercisable as of December 31, 2015	77,000
Options Exercisable, Weighted Average Exercise Price	$ 9.09
Range of Exercise Prices, Lower Limit	8.41
Range of Exercise Prices, Upper Limit	$ 9.45

EQUITY INCENTIVE PLANS - Shares

EQUITY INCENTIVE PLANS - Shares vested, expected to vest and exercisable (Details 2) - Stock Options $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested and unvested expected to vest shares | shares	8,119,246
Vested and unvested expected to vest, weighted-average exercise price | $ / shares	$ 4.24
Vested and unvested expected to vest, weighted-average remaining contractual term (in years)	5 years 2 months 16 days
Vested and unvested expected to vest, aggregate intrinsic value | $	$ 1,265
Exercisable shares | shares	5,756,625
Exercisable, weighted-average exercise price | $ / shares	$ 5.12
Exercisable, weighted-average remaining contractual term (in years)	3 years 9 months 26 days
Exercisable, aggregate intrinsic value | $	$ 83

EQUITY INCENTIVE PLANS - Restri

EQUITY INCENTIVE PLANS - Restricted stock activity (Details 3) - Restricted Stock	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Number of Shares
Unvested as of December 31, 2014 | shares	105,665
Granted | shares
Vested | shares	(36,101)
Cancelled | shares	(10,929)
Unvested as of December 31, 2015 | shares	58,635
Weighted Average Grant Date Fair Value
Unvested as of December 31, 2014 | $ / shares	$ 2.51
Granted | $ / shares
Vested | $ / shares	$ 2.51
Cancelled | $ / shares	2.51
Unvested as of December 31, 2015 | $ / shares	$ 2.51

EQUITY INCENTIVE PLANS (Detail

EQUITY INCENTIVE PLANS (Detail Textuals) - Stock Options - shares	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015
2014 Equity Incentives Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized	3,750,000
Options granted term	10 years
Award vesting period	4 years
Percentage of ownership	10.00%
Percentage of market fair value of the common stock	110.00%
Options weighted average remaining contractual term for major investors	5 years
Number of shares available for grant		2,433,650
1994 Amended and Restated Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant		1,611,324

EQUITY INCENTIVE PLANS (Detai52

EQUITY INCENTIVE PLANS (Detail Textuals 1) - Director Incentive Plan - Stock Options - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized		1,200,000
Number of shares granted	1,247,500
Number of shares currently exercisable	820,000
Number of shares available for grant	266,500
Board of Directors Chairman
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for initial election		25,000
Award vesting period for initial election		3 years
Number of shares authorized for re-election		25,000
Award vesting period for re - election		1 year
Director
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for initial election		30,000
Award vesting period for initial election		3 years
Number of shares authorized for re-election		15,000
Award vesting period for re - election		1 year

EQUITY INCENTIVE PLANS (Detai53

EQUITY INCENTIVE PLANS (Detail Textuals 2) - Equity Incentive Plan - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of options outstanding	$ 1,363
Weighted average grant date fair value of options granted	$ 0.77	$ 1.65	$ 1.69
Intrinsic value of options exercised	$ 0	$ 0	$ 1
Compensation cost not yet recognized	$ 2,545
Compensation cost related to non-vested option awards recognition period	2 years 3 months 18 days
Number of the non-vested options forfeited during the period	205,980
Weighted average grant date fair value of the options non vested which are forfeited during the period	$ 1.48
Weighted average exercise price of the options non vested which are forfeited during the period	$ 2.35
Number of the non-vested options shares expired during the period	726,534
Weighted average grant date fair value of the options non vested which are expired during the period	$ 3.30
Weighted average exercise price of the options non vested which are expired during the period	$ 5.52
Weighted average remaining contractual life for options exercisable	3 years 9 months 18 days

EQUITY INCENTIVE PLANS (Detai54

EQUITY INCENTIVE PLANS (Detail Textuals 3) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 2,261,000	$ 3,282,000	$ 3,943,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted
Weighted average grant date fair value for the options granted during the period
Equity Incentive Plan | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	0	0	242,697
Award vesting period			4 years
Weighted average grant date fair value for the options granted during the period			$ 2.51
Share-based compensation expense	$ 76,000	$ 88,000	$ 187,000
Fair value of the stock vested during the period	$ 78	$ 78	$ 206

EQUITY INCENTIVE PLANS (Detai55

EQUITY INCENTIVE PLANS (Detail Textuals 4) - shares	1 Months Ended
	Mar. 31, 2013	Feb. 29, 2012	Jul. 31, 2010
Chief executive officer employment agreement | Chief executive officer (CEO) | Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted			100,000
Chief executive officer employment agreement | Chief executive officer (CEO) | Stock Options | Vested upon grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of options vested			25.00%
Chief executive officer employment agreement | Chief executive officer (CEO) | Stock Options | Vest annually
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of options vested			25.00%
Award vesting period			3 years
Chief executive officer employment agreement | Chief executive officer (CEO) | Performance-based stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stocks vested during the period			390,000
Chief medical officer employment agreement | Chief medical officer (CMO) | Performance-based stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stocks vested during the period	120,000	50,000
Chief operating officer employment agreement | Chief operating officer (COO) | Performance-based stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stocks vested during the period	125,000

EQUITY INCENTIVE PLANS (Detai56

EQUITY INCENTIVE PLANS (Detail Textuals 5) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 2,261	$ 3,282	$ 3,943
Employee Stock Purchase Plan ("Purchase Plan")
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares purchased	2,146,540
Number of shares available for grant	253,460
Share-based compensation expense	$ 60	$ 58	$ 124
Stock Options | Employee Stock Purchase Plan ("Purchase Plan")
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of market fair value of the common stock	85.00%
Options exercises period	27 months
Number of shares authorized				2,400,000

INCOME TAXES - Reconciliation b

INCOME TAXES - Reconciliation between the U.S. federal statutory rate and the effective tax rate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
Income tax (benefit) expense at statutory rate	$ (4,683)	$ (7,953)	$ (8,364)
State tax (benefit) expense, net of Federal tax (benefit) expense	(677)	(1,154)	(901)
Permanent items	239	383	516
Effect of change in valuation allowance and State NOL expiration	4,945	9,402	10,862
Tax credits	(74)	$ (678)	$ (2,113)
Other	$ 250
Tax expense (benefit)

INCOME TAXES - Income tax effec

INCOME TAXES - Income tax effect of temporary differences comprising the deferred tax assets and deferred tax liabilities (Details 1) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Net operating loss carryforwards	$ 125,599	$ 115,747
Tax credit carryforwards	25,036	24,962
Equity based compensation	9,176	8,558
Book depreciation in excess of tax	35	1,352
Reserves and accruals	276	52
Deferred revenue	1,796	6,115
Loss on investment		194
Other	26	19
Deferred tax assets, gross	161,944	156,999
Valuation allowance	$ (161,944)	$ (156,999)
Deferred tax liabilities
Net deferred tax assets

INCOME TAXES (Detail Textuals)

INCOME TAXES (Detail Textuals) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Operating Loss Carryforwards [Line Items]
Amount of valuation allowance increased	$ 4,945
Increase in ownership percentage of certain stockholders or public groups	more than 50 percentage points
Ownership change, increase in ownership percentage, term	3 years
Federal income tax
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 357,122
Net operating loss generated from excess tax deduction from share based awards	15,020
State income tax
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	176,712
Net operating loss generated from excess tax deduction from share based awards	868
Research and development credit carryforwards
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 27,750

RESTRUCTURING AND OTHER COSTS (

RESTRUCTURING AND OTHER COSTS (Detail Textuals) $ in Thousands	Aug. 04, 2014USD ($)Employee	Jul. 31, 2013PositionEmployee	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Restructuring Cost and Reserve [Line Items]
Number of position reduced | Position		26
Number of employee before restructuring | Employee	62	68
Number of employee remained after implementation of restructuring | Employee	40
Amount paid for restructuring			$ 319
Remaining amount expected to be paid			417
Impairment of property and equipment			280
Severance payments
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost	$ 662			$ 422
Benefits continuation costs
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost	$ 74			89
Modification of employee stock options
Restructuring Cost and Reserve [Line Items]
Expected restructuring cost			$ 83	$ 139

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Minimum lease commitments for all leased facilities, net of sublease income (Details) $ in Thousands	Dec. 31, 2015USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,016	$ 529
2,017	488
2,018	484
2,019	499
Thereafter	296
Total minimum lease payments	$ 2,296

COMMITMENTS AND CONTINGENCIES62

COMMITMENTS AND CONTINGENCIES (Detail Textuals) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commitments And Contingencies Disclosure [Line Items]
Rent expense under non-cancelable operating leases		$ 1,569	$ 2,866	$ 2,866
Lease Agreement
Commitments And Contingencies Disclosure [Line Items]
Lease term	5 years 3 months
Lease average annual rental rate amount	$ 455

CONCENTRATION OF CREDIT RISK (D

CONCENTRATION OF CREDIT RISK (Detail Textuals) - Customer Concentration Risk - Revenue	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Customer One
Concentration Risk [Line Items]
Percentage of total sales accounted	49.00%	49.00%	53.00%
Customer Two
Concentration Risk [Line Items]
Percentage of total sales accounted	51.00%	51.00%	36.00%
Customer Three
Concentration Risk [Line Items]
Percentage of total sales accounted			11.00%

SELECTED QUARTERLY FINANCIAL 64

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) - Quarterly financial data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Net revenues	$ 2,797	$ 2,653	$ 3,004	$ 2,785	$ 3,015	$ 2,662	$ 2,901	$ 2,676	$ 11,239	$ 11,254	$ 15,914
Net loss	$ (2,852)	$ (2,354)	$ (4,017)	$ (4,551)	$ (3,512)	$ (6,399)	$ (6,339)	$ (7,141)	$ (13,774)	$ (23,391)	$ (24,600)
Basic and diluted net loss per share:
Net loss per share (in dollars per share)	$ (0.05)	$ (0.04)	$ (0.06)	$ (0.07)	$ (0.06)	$ (0.10)	$ (0.10)	$ (0.11)	$ (0.22)	$ (0.37)	$ (0.39)

SUBSEQUENT EVENT (Detail Textua

SUBSEQUENT EVENT (Detail Textuals) - Subsequent event - Definitive stock purchase agreements $ / shares in Units, $ in Millions	2 Months Ended
	Feb. 26, 2016USD ($)$ / sharesshares
Subsequent Event [Line Items]
Number of common shares issued to institutional and accredited investors | shares	8,030,000
Number of shares authorized for non-transferable options | shares	3,570,000
Aggregate proceeds from common stock and non-transferable options | $	$ 15.3
Options Exercisable, Weighted Average Exercise Price | $ / shares	$ 2.50
Additional proceeds from common stock and non-transferable options | $	$ 8.9