Arqule (ARQL) 10-K 7 Mar 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 20, 2019	Jun. 30, 2018
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		109,003,637
Entity Public Float			$ 531,446,974
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false

BALANCE SHEETS

BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 19,236	$ 20,229
Marketable securities-short term	80,322	27,807
Contract receivables	5,984
Prepaid expenses	861	547
Total current assets	106,403	48,583
Property and equipment, net	69	115
Other assets	204	204
Total assets	106,676	48,902
Current liabilities:
Accounts payable and accrued expenses	12,948	8,259
Notes payable-current portion	1,667
Deferred revenue		1,500
Total current liabilities	14,615	9,759
Long-term liabilities:
Notes payable-long term	13,093	14,607
Warrant liability		1,512
Total liabilities	27,708	25,878
Commitments and contingencies (Note 13)
Preferred stock, convertible, Series A $0.01 par value; 1,000,000, shares authorized; zero and 8,370 shares issued and outstanding at December 31, 2018 and 2017, respectively		8,843
Stockholders' equity:
Common stock, $0.01 par value; 200,000,000 shares authorized; 109,003,637 and 87,110,202 shares issued and outstanding at December 31, 2018 and 2017, respectively	1,090	871
Additional paid-in capital	625,993	547,364
Accumulated other comprehensive loss	(95)	(16)
Accumulated deficit	(548,020)	(534,038)
Total stockholders' equity	78,968	14,181
Total liabilities, preferred stock and stockholders' equity	$ 106,676	$ 48,902

BALANCE SHEETS (Parentheticals)

BALANCE SHEETS (Parentheticals) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Series A Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Series A Preferred stock, shares authorized	1,000,000	1,000,000
Series A Preferred stock, shares issued	0	8,370
Series A Preferred stock, shares outstanding	0	8,370
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	109,003,637	87,110,202
Common stock, shares outstanding	109,003,637	87,110,202

STATEMENTS OF OPERATIONS AND CO

STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Research and development revenue	$ 25,764		$ 4,709
Costs and expenses:
Research and development	28,710	$ 19,468	20,042
General and administrative	10,753	7,551	7,563
Total costs and expenses	39,463	27,019	27,605
Loss from operations	(13,699)	(27,019)	(22,896)
Interest income	1,435	238	178
Interest expense	(1,666)	(1,520)
Other expense	(1,552)	(902)
Loss before income taxes	(15,482)	(29,203)	(22,718)
Provision for income taxes	0	0	0
Net loss	(15,482)	(29,203)	(22,718)
Unrealized loss on marketable securities	(79)	(18)	(1)
Comprehensive loss	$ (15,561)	$ (29,221)	$ (22,719)
Basic and diluted net loss per common share:
Net loss per common share (in dollars per share)	$ (0.16)	$ (0.39)	$ (0.33)
Weighted average basic and diluted common shares outstanding (in shares)	99,035	74,813	69,714

STATEMENTS OF STOCKHOLDERS' EQU

STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	PREFERRED STOCK	COMMON STOCK	ADDITIONAL PAID-IN CAPITAL	ACCUMULATED OTHER COMPREHENSIVE INCOME/(LOSS)	ACCUMULATED DEFICIT	Total
Balance at Dec. 31, 2015		$ 629	$ 510,664	$ 3	$ (482,117)	$ 29,179
Balance (in shares) at Dec. 31, 2015		62,939,780
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and warrants from stock offering, net		$ 80	15,094			15,174
Issuance of common stock and warrants from stock offering, net (in shares)		8,027,900
Stock option exercises and issuance of common stock		$ 1	112			113
Stock option exercises and issuance of common stock (in shares)		97,498
Restricted shares issued net of forfeitures and shares redeemed for taxes (in shares)		29,828
Employee stock purchase plan		$ 1	67			68
Employee stock purchase plan (in shares)		51,203
Stock based compensation expense			1,865			1,865
Change in unrealized loss on marketable securities				(1)		(1)
Net loss					(22,718)	(22,718)
Balance at Dec. 31, 2016		$ 711	527,802	2	(504,835)	23,680
Balance (in shares) at Dec. 31, 2016		71,146,209
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of preferred stock and preferred warrants from stock offerings, net	$ 8,843
Issuance of preferred stock and preferred warrants from stock offerings, net (in shares)	8,370
Issuance of common stock and warrants from stock offering, net		$ 160	17,764			17,924
Issuance of common stock and warrants from stock offering, net (in shares)		15,938,651
Restricted shares issued net of forfeitures and shares redeemed for taxes (in shares)		5,380
Employee stock purchase plan			17			17
Employee stock purchase plan (in shares)		19,962
Stock based compensation expense			1,434			1,434
Issuance of warrants from notes payable			347			347
Change in unrealized loss on marketable securities				(18)		(18)
Net loss					(29,203)	(29,203)
Balance at Dec. 31, 2017	$ 8,843	$ 871	547,364	(16)	(534,038)	$ 14,181
Balance (in shares) at Dec. 31, 2017	8,370	87,110,202				87,110,202
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of preferred stock and warrants due to conversion of preferred stock to common stock and preferred warrants to common warrants	$ (8,843)	$ 83	11,823			$ 11,906
Issuance of preferred stock and warrants due to conversion of preferred stock to common stock and preferred warrants to common warrants (in shares)	(8,370)	8,370,000
Issuance of common stock and warrants from stock offering, net		$ 127	64,435			64,562
Issuance of common stock and warrants from stock offering, net (in shares)		12,650,000
Stock option exercises and issuance of common stock		$ 6	750			756
Stock option exercises and issuance of common stock (in shares)		603,851
Shares issued from exercise of warrants		$ 3	(2)			1
Shares issued from exercise of warrants (in shares)		269,584
Stock based compensation expense			1,503			1,503
Warrants issued upon debt extension			120			120
Change in unrealized loss on marketable securities				(79)		(79)
Increase to opening accumulated deficit upon adoption of new accounting standard					1,500	1,500
Net loss					(15,482)	(15,482)
Balance at Dec. 31, 2018		$ 1,090	$ 625,993	$ (95)	$ (548,020)	$ 78,968
Balance (in shares) at Dec. 31, 2018		109,003,637				109,003,637

STATEMENTS OF CASH FLOWS

STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net loss	$ (15,482)	$ (29,203)	$ (22,718)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	46	65	101
Amortization of premium (discount) on marketable securities	691	(28)	48
Amortization of debt discount	322	330
Change in fair value of warrant liability	1,552	902
Non-cash stock compensation	1,503	1,434	1,865
Changes in operating assets and liabilities:
Contract receivables	(5,984)
Prepaid expenses and other assets	(314)	322	(108)
Accounts payable and accrued expenses	4,690	(497)	2,466
Deferred revenue		1,500	(4,591)
Net cash used in operating activities	(12,976)	(25,175)	(22,937)
Cash flows from investing activities:
Purchases of marketable securities	(112,580)	(41,971)	(30,975)
Proceeds from sale or maturity of marketable securities	59,295	30,033	39,856
Purchases of property and equipment			(15)
Net cash provided by (used in) investing activities	(53,285)	(11,938)	8,866
Cash flows from financing activities:
Proceeds from notes payable and warrants		15,000
Debt issuance costs associated with notes payable and warrants	(49)	(376)
Proceeds from common stock offerings and warrants, net	64,561	17,951	15,174
Proceeds from convertible preferred stock offering and warrants, net		9,483
Proceeds from stock option exercises and employee stock plan purchases	756	17	181
Net cash provided by financing activities	65,268	42,075	15,355
Net increase (decrease) in cash and cash equivalents	(993)	4,962	1,284
Cash and cash equivalents, beginning of period	20,229	15,267	13,983
Cash and cash equivalents, end of period	19,236	20,229	15,267
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION (IN THOUSANDS):
Interest on debt	1,344	1,190	0
Income taxes	$ 0	$ 0	$ 0

ORGANIZATION AND NATURE OF OPER

ORGANIZATION AND NATURE OF OPERATIONS	12 Months Ended
	Dec. 31, 2018
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 product candidates 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 clinical-stage pipeline consists of four product candidates, all of which are in targeted patient populations, making ArQule a leader among companies our size in precision medicine. ArQule has a long history of kinase drug discovery and development, having discovered and introduced ten kinase inhibitors into clinical trials. Our drug discovery efforts have been informed by our historical expertise in chemistry, our work in rational drug design and by our insight into kinase binding and regulation. We have applied this knowledge to produce significant chemical matter for a number of kinase targets and to build an extensive library of proprietary compounds with the potential to target multiple kinases in oncology and other therapeutic areas, such as rare diseases. We may bring further preclinical programs forward and interrogate our library against new targets beyond kinases either directly or with collaborators. Our proprietary pipeline of orally bioavailable 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. All of these programs are being developed in targeted, biomarker-defined patient populations. By seeking out subgroups of patients that are most likely to respond to our product candidates, we seek to identify small, often orphan, indications that allow for focused and efficient development. At the same time, in addition to pursuing these potentially fast-to-market strategies, we also pursue development in other indications that could allow us to expand the utility of the product candidates if approved. Our clinical pipeline includes the following product candidates: • ARQ 531 is a potent and reversible dual inhibitor of both wild type and C481S-mutant Bruton’s tyrosine kinase (BTK) that is in Phase 1 clinical development for B-cell malignancies refractory to other therapeutic options; • Miransertib (ARQ 092) is a potent and selective inhibitor of protein kinase B (AKT), a serine/ threonine kinase. We expect to commence a registrational clinical trial of miransertib for the treatment of Proteus syndrome and PIK3CA-Related Overgrowth Syndromes (PROS) in the first half of 2019. Miransertib is also in Phase 1b clinical development in oncology in combination with the hormonal therapy, anastrozole; • ARQ 751 is a next-generation, highly potent and selective inhibitor of AKT that is in Phase 1 clinical development for solid tumors harboring AKT, phosphoinositide 3-kinase (PI3K) or phosphatase and tensin homolog (PTEN) loss mutations; and • Derazantinib (ARQ 087) is a multi-kinase inhibitor designed to preferentially inhibit the fibroblast growth factor receptor (FGFR) family of kinases that is in a registrational clinical trial in intrahepatic cholangiocarcinoma (iCCA) in patients with FGFR2 fusions. Derazantinib was exclusively licensed to Basilea Pharmaceutica Limited (Basilea) in April 2018 in the United States, European Union, Japan and the rest of the world, excluding the People’s Republic of China, Hong Kong, Macau, and Taiwan (collectively, Greater China) where derazantinib was exclusively licensed to Sinovant Sciences Ltd., a subsidiary of Roivant Sciences Ltd. (Sinovant) in February 2018. 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 historically consisted primarily of payments received from our collaborators for services performed or upfront payments for future services. In the year ended December 31, 2018, our net use of cash was primarily driven by the difference between cash received from our collaborations and payments for operating expenses which resulted in net cash outflows of $13.0 million. For the year ended December 31, 2017 net use of cash was primarily driven by payments for operating expenses which resulted in net cash outflows of  $25.2 million. Our cash requirements may vary materially from those now planned depending on 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 product candidates into a commercial product. In February 2016, we entered into definitive stock purchase agreements with certain institutional and accredited investors. In conjunction with this stock offering we issued 8,027,900 shares of our common stock for aggregate net proceeds of  $15.2 million. In January 2017, we entered into a loan and security agreement with Oxford Finance, LLC (the “Loan Agreement”) with a principal balance of $15 million (see Note 8). The Loan Agreement required interest-only payments for 18 months, followed by an amortization period of 36 months. The original maturity date of the loan was August 1, 2021 and in February 2018 we signed an amendment with the lender which extended the maturity date by one year to August 1, 2022 with principal payments commencing on September 1, 2019. In September 2017, we sold 2.0 million shares of common stock through an at-the-market (“ATM”) offering and raised net proceeds of approximately $2.3 million. In October 2017, we entered into definitive securities purchase agreements with certain institutional investors. In conjunction with this stock offering, we issued 13,938,651 shares of our common stock and warrants for 3,123,674 shares of our common stock for aggregate net proceeds of  $15.6 million. Each warrant is exercisable at a price of  $1.75 per share and expires in October 2021. In November 2017, we entered into definitive securities purchase agreements with certain institutional investors. In conjunction with this stock offering we raised net proceeds of  $9.5 million through the sale of 8,370 shares of series A convertible preferred stock (Series A Preferred) and warrants to purchase 2,259 shares of Series A Preferred (Warrants). Each share of Series A Preferred converted into 1,000 shares of common stock and each associated Warrant converted into 1,000 common stock warrants upon the effectiveness on May 8, 2018 of an amendment to our restated certificate of incorporation to increase the number of authorized shares of common stock thereunder. The Warrants have a post-conversion exercise price of  $1.75 per share, are exercisable immediately and expire in May 2022. In February 2018, we entered into a License Agreement with Sinovant pursuant to which ArQule granted Sinovant an exclusive license to develop and commercialize derazantinib in the People’s Republic of China, Hong Kong, Macau, and Taiwan (collectively, Greater China). The agreement provides for an upfront payment to ArQule of  $3 million and a $2.5 million development milestone that was paid in the first quarter of 2019. We are also eligible for up to an additional $82 million in regulatory and sales milestones. Upon commercialization, we are entitled to receive double digit royalties in the low teens from Sinovant on net sales of derazantinib in Greater China. Sinovant will be responsible for all costs and expenses of development, manufacture and commercialization in Greater China. In April 2018, we entered into a License Agreement with Basilea pursuant to which ArQule granted Basilea an exclusive license to develop and commercialize derazantinib in the United States, European Union, Japan and the rest of the world, excluding Greater China. Under the terms of the agreement, we received an upfront payment of  $10 million and are eligible for up to $326 million in regulatory and commercial milestones. Upon commercialization, we are entitled to receive staggered royalties on future net sales of derazantinib ranging from the high-single digits to the mid-teens on direct sales and mid-single digits to low-double digits on indirect sales. Basilea will be responsible for all costs and expenses of development, manufacture and commercialization in its territory. Under certain circumstances, we may have the opportunity to promote derazantinib in the United States directly. In July 2018, we sold 12,650,000 shares of common stock at $5.50 per share for aggregate net proceeds of approximately $64.6 million after commissions and other estimated offering expenses. We anticipate that our cash, cash equivalents and marketable securities on hand at December 31, 2018, financial support from our licensing agreements and the one year extension of our loan agreement mentioned above will be sufficient to finance our operations for at least 12 months from the issuance date of these financial statements. We expect that 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, 2018
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. We classify our investments as either current or long-term based upon the investments’ contractual maturities and our 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, 2018 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, 2018, 2017 or 2016. 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 Measurements Certain of our assets are carried at fair value under U.S. generally accepted accounting principles (GAAP). Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. At December 31, 2018 and 2017 our financial instruments consisted of cash, cash equivalents, investments in corporate debt securities, accounts payable, notes payable and accrued expenses. At December 31, 2018 and 2017, our financial instruments also included marketable securities which are reported at fair value. At December 31, 2017 our financial instruments also included warrant liabilities reported at fair value. The warrant liability was carried at fair value and determined to be a Level 3 liability in the fair value hierarchy described above. The carrying values of cash, cash equivalents, investments in corporate debt securities, marketable securities, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities. The carrying value of our notes payable approximates their fair value. 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, 2018, 2017 and 2016 was $46, $65 and $101, respectively. Revenue Recognition—Research and Development Revenue Research and development revenue is generated primarily through collaborative research and development agreements and license 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. Our policy is to recognize revenues when our customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. We recognize revenues following the five step model prescribed under Accounting Standards Codification Topic 606—Revenue from Contracts with Customers. Under Topic 606 we: (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenues when (or as) we satisfy the performance obligation. We only apply the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, we assess the goods or services promised within each contract, and determine those that are performance obligations. The transaction price is allocated to the identified performance obligations in proportion to their estimated standalone selling prices (SSP) on a relative basis. Determining the estimated SSP for performance obligations requires judgment. In developing the SSP for a performance obligation, we consider applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. Revenue is recognized when each distinct performance obligation is satisfied. For certain performance obligations that are satisfied over time we recognize revenue using the cost-to-cost method. Under the cost-to-cost method, the extent of progress towards completion is measured based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the identified performance obligation. Under this method, revenue will be recorded as a percentage of the estimated transaction price based on the extent of progress towards completion. Incurred cost represents work performed, which corresponds with, and thereby best depicts, the transfer of control to the customer. Due to the nature of the work performed in these arrangements, the estimation of cost at completion is subject to many variables and requires judgment. Circumstances can arise that change original estimates of costs or progress toward completion. Changes to the estimated cost at completion have not had a material impact on the results of operations. 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. 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 14 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 (Expense) Other income (expense) in 2018 includes a non-cash expense of  $1,552 from an increase in fair value of our preferred stock warrant liability. The preferred stock warrant liability was eliminated upon the conversion of the preferred shares into common shares in the year ended December 31, 2018. Other income (expense) in 2017 includes a non-cash expense of  $902 from an increase in fair value of our preferred stock warrant liability. Other income (expense) was $0 in 2016. 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, we recognize the benefit of uncertain tax positions in the financial statements. Earnings (Loss) Per Share Net loss per share is computed using the weighted average number of common shares outstanding. Basic and diluted net loss per share amounts are equivalent for the periods presented as the inclusion of potential common shares in the number of shares used for the diluted computation would be anti-dilutive to loss per share. Potential common shares, for the year ended December 31, 2018, include 10,748,157 shares that would be issued upon the exercise of outstanding employee and Board of Director stock options, 93,168 shares that would be issued upon the exercise of the warrants from the February 2018 amendment to our loan agreement, 3,123,674 shares that would be issued upon the exercise of the warrants from our October 2017 common stock offering, and 2,259,000 common shares that would be issued upon the exercise of the warrants from our November 2017 preferred stock offering. The shares and warrants from our November 2017 preferred stock offering were converted on May 8, 2018 to common shares and warrants. Potential common shares, for the year ended December 31, 2017, include 10,622,455 shares that would be issued upon the exercise of outstanding employee and Board of Director stock options, 354,330 shares that would be issued upon the exercise of the warrants from our January 2017 loan agreement, 3,123,674 shares that would be issued upon the exercise of the warrants from our October 2017 common stock offering, 8,370,000 common shares that would be issued upon the conversion of the shares from our November 2017 preferred stock offering and 2,259,000 common shares that would be issued upon the exercise of the warrants from our November 2017 preferred stock offering. Potential common shares for the year ended December 31, 2016, include 8,715,048 shares that would be issued upon the exercise of outstanding employee and Board of Director stock options and options to purchase 3,567,956 shares that would have been issued upon the exercise of the options from our February 2016 common stock offering. The options issued in conjunction with the February 2016 common stock offering expired in 2017. 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, 2018, 2017 and 2016 included in our Statements of Operations and Comprehensive Loss: 2018 2017 2016 Research and development $ 369 $ 359 $ 514 General and administrative 1,134 1,075 1,351 Total stock-based compensation expense $ 1,503 $ 1,434 $ 1,865 In the years ended December 31, 2018, 2017 and 2016, 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, 2018, 2017 and 2016 respectively were estimated on the grant date using the Black-Scholes option-pricing model with the following assumptions: 2018 2017 2016 Dividend yield(1) 0.0% 0.0% 0.0% Weighted average expected volatility factor(2) 62% 62% 63% Risk free interest(3) 2.4–2.9% 1.9–2.1% 1.2–1.8% Expected term, excluding options issued pursuant to the Employee Stock Purchase Plan(4) 5.6–7.2 years 6.1–7.1 years 5.8–7.2 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 us 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 May 2017 the FASB issued Accounting Standard Update (“ASU”) No. 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting. This new standard provides clarity and reduces both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, Compensation-Stock Compensation, to a change to the terms or conditions of a share-based payment award. This new standard became effective for us on January 1, 2018. The adoption of this standard did not have a material impact on our financial position or results of operations. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. This new standard clarifies certain aspects of the statement of cash flows, including the classification of debt prepayment or debt extinguishment costs or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, distributions received from equity method investees and beneficial interests in securitization transactions. This new standard also clarifies that an entity should determine each separately identifiable source of use within the cash receipts and payments on the basis of the nature of the underlying cash flows. In situations in which cash receipts and payments have aspects of more than one class of cash flows and cannot be separated by source or use, the appropriate classification should depend on the activity that is likely to be the predominant source or use of cash flows for the item. This new standard became effective for us on January 1, 2018. The adoption of this standard did not have a material impact on our statements of cash flows upon adoption. In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The new standard involves several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. We adopted this ASU in 2017 and it did not have a material impact on our financial position, results of operations or statement of cash flows. In February 2016 the FASB issued ASU No. 2016-02, Leases (Topic 842). This standard established a right-of-use model that requires all lessees to recognize right-of-use assets and liabilities on their balance sheet that arise from leases with terms longer than 12 months as well as provide disclosures with respect to certain qualitative and quantitative information related to their leasing arrangements. This standard became effective for us on January 1, 2019. The FASB has subsequently issued the following amendments to ASU 2016-02, which have the same effective date and transition date of January 1, 2019, and which we collectively refer to as the new leasing standards: • ASU No. 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842, which permits an entity to elect an optional transition practical expedient to not evaluate under Topic 842 land easements that exist or expired prior to adoption of Topic 842 and that were not previously accounted for as leases under the prior standard, ASC 840, Leases. • ASU No. 2018-10, Codification Improvements to Topic 842, Leases, which amends certain narrow aspects of the guidance issued in ASU 2016-02. • ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, which allows for a transition approach to initially apply ASU 2016-02 at the adoption date and recognize a cumulative-effect adjustment to the opening balance of accumulated deficit in the period of adoption as well as an additional practical expedient for lessors to not separate non-lease components from the associated lease component. • ASU No. 2018-20, Narrow-Scope Improvements for Lessors, which contains certain narrow scope improvements to the guidance issued in ASU 2016-02. We adopted the new leasing standards on January 1, 2019, using a modified retrospective transition approach to be applied to leases existing as of, or entered into after, January 1, 2019. We have reviewed our existing lease contracts and the impact of the new leasing standards on our results of operations, financial position and disclosures. Upon adoption of the new leasing standards, we expect to recognize a lease liability and related right-of-use asset on our balance sheet of approximately $0.7 million. We expect that the impact of adoption of the new leasing standards will not have a material impact on our statement of income. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes (Topic 740), which requires that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position to simplify the presentation of deferred income taxes. This new standard became effective for us on January 1, 2017 and did not have a material impact on our disclosures. In May 2014 the FASB issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry specific guidance. The FASB subsequently issued amendments to ASU No. 2014-09 that have the same effective date and transition date. This standard requires a company to recognize revenues 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. Under the new revenue standards, we recognize revenues when our customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. We recognize revenues following the five-step model prescribed under Topic 606: (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenues when (or as) we satisfy the performance obligation. We only apply the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, we assess the goods or services promised within each contract, and determines those that are performance obligations. The transaction price is allocated to the identified performance obligations in proportion to their estimated standalone selling prices (SSP) on a relative basis. Determining the estimated SSP for performance obligations requires judgment. In developing the SSP for a performance obligation, we consider applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. Revenue is recognized when each distinct performance obligation is satisfied. For certain performance obligations that are satisfied over time the we recognize revenue using the cost-to-cost method. Under the cost-to-cost method, the extent of progress towards completion is measured based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the identified performance obligation. Under this method, revenue will be recorded as a percentage of the estimated transaction price based on the extent of progress towards completion. Incurred cost represents work performed, which corresponds with, and thereby best depicts, the transfer of control to the customer. Due to the nature of the work performed in these arrangements, the estimation of cost at completion is subject to many variables and requires judgment. Circumstances can arise that change original estimates of costs or progress toward completion. Changes to the estimated cost at completion have not had a material impact on the results of operations. We adopted Accounting Standards Codification Topic 606—Revenue from Contracts with Customers, or Topic 606, on January 1, 2018, using the modified retrospective approach and resulted in a change to its accounting policy for revenue recognition. Results for reporting periods beginning after January 1, 2018 are presented under the new standard, while prior period amounts are not adjusted and continue to be reported under the accounting standards in effect for the prior period. We recorded a net increase to opening equity of  $1.5 million as of January 1, 2018 due to the cumulative impact of adopting this new standard. Without applying the new revenue standard, the disclosed research and development revenue would have been $1.4 million higher than currently disclosed for the year ended December 31, 2018. Contract receivables were $6.0 million at December 31, 2018. The adoption of the new revenue standard did not have a material impact on any other balances within the financial statements as of and for the year ended December 31, 2018. However, the adoption of the new revenue standards will result in a change in the timing of revenue recognition related to certain of our licensing agreements based upon the terms of the underlying agreements.

COLLABORATIONS AND ALLIANCES

COLLABORATIONS AND ALLIANCES	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation Of Financial Statements [Abstract]
COLLABORATIONS AND ALLIANCES	3. COLLABORATIONS AND ALLIANCES Basilea Licensing Agreement In April 2018, we entered into a License Agreement with Basilea pursuant to which ArQule granted Basilea an exclusive license to develop and commercialize derazantinib in the United States, European Union, Japan and the rest of the world, excluding Greater China. Under the terms of the agreement, we received an upfront payment of  $10 million and are eligible for up to $326 million in regulatory and commercial milestones. Upon commercialization, we are entitled to receive staggered royalties on future net sales of derazantinib ranging from the high-single digits to the mid-teens on direct sales and mid-single digits to low-double digits on indirect sales. Basilea will be responsible for all costs and expenses of development, manufacture and commercialization in its territory. Under certain circumstances, we may have the opportunity to promote derazantinib in the United States directly. Revenue in the year ended December 31, 2018 totaled $18.5 million for providing the technology license as well as certain research and development services to Basilea, recognized as revenue on a cost-to-cost method. Sinovant Licensing Agreement In February 2018, we entered into a License Agreement with Sinovant pursuant to which ArQule granted Sinovant an exclusive license to develop and commercialize derazantinib in Greater China. The agreement provides for an upfront payment to ArQule of  $3 million and a $2.5 million development milestone that was paid in the first quarter of 2019. We are also eligible for up to an additional $82 million in regulatory and sales milestones. Upon commercialization, we are entitled to receive double digit royalties in the low teens from Sinovant on net sales of derazantinib in Greater China. Sinovant will be responsible for all costs and expenses of development, manufacture and commercialization in Greater China. For the year ended December 31, 2018, we recognized revenue of  $5.9 million related to the Sinovant agreement, including $0.4 million for certain research and development services that we provided. Other Licensing Agreements In October 2017, we entered into a non-exclusive license agreement for certain library compounds. The licensed compounds were delivered and are subject to quality and acceptance testing. In 2017, we recorded deferred revenue of  $1.5 million related to this licensing agreement which was recorded as an opening adjustment to accumulated deficit upon the adoption of Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers on January 1, 2018. For the year ended December 31, 2018, we recorded revenue of  $1.3 million based upon the achievement of the quality and acceptance testing under this completed agreement. Tivantinib Agreements We entered into licensing agreements with Daiichi Sankyo and Kyowa Hakko Kirin in December 2008 and May 2007, respectively, related to the development and commercialization of tivantinib. In 2017, we announced that the trials of tivantinib did not meet their primary end points and as a result, we, Daiichi Sankyo and Kyowa Hakko Kirin have all discontinued development of tivantinib.

MARKETABLE SECURITIES AND FAIR

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS	12 Months Ended
	Dec. 31, 2018
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. 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 that have investment grade ratings. The following is a summary of the fair value of available-for-sale marketable securities we held at December 31, 2018 and December 31, 2017: December 31, 2018 Amortized Cost Gross Gains Gross Losses Fair Value Security type Corporate debt securities-short term $ 80,417 $ 2 $ (97 ) $ 80,322 Total available-for-sale marketable securities $ 80,417 $ 2 $ (97 ) $ 80,322 December 31, 2017 Amortized Cost Gross Gains Gross Losses Fair Value Security type Corporate debt securities-short term $ 27,823 $ 1 $ (17 ) $ 27,807 Total available-for-sale marketable securities $ 27,823 $ 1 $ (17 ) $ 27,807 None of our available-for-sale marketable securities were in a continuous unrealized loss position for more than 12 months at December 31, 2018 or 2017. The following table presents information about our assets that are measured at fair value on a recurring basis for the year ended December 31, 2018 and indicates the fair value hierarchy of the valuation techniques we utilized to determine such fair value. There were no transfers in or out of Level 1 or Level 2 measurements for the year ended December 31, 2018: December 31, Quoted Prices in Significant Significant Cash equivalents $ 14,444 $ 14,444 $ — $ — Corporate debt securities-short term 80,322 — 80,322 — Total $ 94,766 $ 14,444 $ 80,322 $ — The following tables present information about our assets and liabilities that are measured at fair value on a recurring basis for the year ended December 31, 2017 and indicates the fair value hierarchy of the valuation techniques we utilized to determine such fair value. There were no transfers in or out of Level 1 or Level 2 measurements for the year ended December 31, 2017: December 31, Quoted Prices in Significant Significant Cash equivalents $ 19,889 $ 19,889 $ — $ — Corporate debt securities-short term 27,807 — 27,807 — Total $ 47,696 $ 19,889 $ 27,807 $ — December 31, Quoted Prices in Significant Significant Warrant liability $ 1,512 $ — $ — $ 1,512 Due to the lack of market quotes relating to our preferred stock warrants, the fair value of the preferred stock warrants was determined at December 31, 2017 using the Black-Scholes model, which is based on Level 3 inputs. As of December 31, 2017, inputs used in the Black-Scholes model are presented below. Based on the Black-Scholes model, we recorded a preferred stock warrants liability of  $1,512 at December 31, 2017. Upon conversion of the Series A Preferred to common stock on May 8, 2018 the warrant liability of  $3,064 was extinguished with an offsetting amount included as additional paid-in capital in stockholders’ equity. The following are the Black-Scholes inputs to the warrant liability valuation at December 31, 2017: 2017 Warrant stock price $1.75 Exercise price 1.65 Expected volatility 53.3% Risk-free interest 2.07% Expected term 3.85 years Dividends none The following is a summary of the activity in the fair value of our warrant liability for the year ended December 31, 2018: Amount Warrant liability as of December 31, 2017 $ 1,512 Change in fair value 1,552 Conversion of preferred stock warrants to common stock warrants (3,064 ) Warrant liability as of December 31, 2018 $ —

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	5. PROPERTY AND EQUIPMENT Property and equipment consist of the following at December 31, 2018 and 2017: USEFUL 2018 2017 Machinery and equipment 5 $ 1,611 $ 1,939 Leasehold improvements 3–5 232 232 Furniture and fixtures 7 40 40 Computer equipment 3 2,496 2,497 4,379 4,708 Less: Accumulated depreciation and amortization 4,310 4,593 Net property and equipment $ 69 $ 115

OTHER ASSETS

OTHER ASSETS	12 Months Ended
	Dec. 31, 2018
Other Assets [Abstract]
OTHER ASSETS	6. OTHER ASSETS Other assets include the following at December 31, 2018 and 2017: 2018 2017 Security deposits $ 204 $ 204 Total other assets $ 204 $ 204

ACCOUNTS PAYABLE AND ACCRUED EX

ACCOUNTS PAYABLE AND ACCRUED EXPENSES	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017: 2018 2017 Accounts payable $ 1,329 $ 537 Accrued payroll 1,971 1,448 Accrued outsourced preclinical and clinical fees 8,497 5,409 Accrued professional fees 666 492 Other accrued expenses 485 373 $ 12,948 $ 8,259

LOAN AGREEMENT

LOAN AGREEMENT	12 Months Ended
	Dec. 31, 2018
Long-term Debt, Unclassified [Abstract]
LOAN AGREEMENT	8. LOAN AGREEMENT In January 2017, Oxford Finance LLC, as collateral agent and a lender (the “Lender”), and any additional lenders that may become parties thereto, entered into a loan and security agreement with us (the “Loan Agreement”). Pursuant to the terms of the Loan Agreement, the Lender issued us a loan in the principal amount of $15.0 million. The loan will bear interest at the rate equal to (a) the greater of  (i) the 30 day U.S. LIBOR rate reported in the Wall Street Journal on the date occurring on the last business day of the month that immediately precedes the month in which the interest will accrue or (ii) 0.65% (b) plus 6.85%. The applicable interest rate on the loan at December 31, 2018 was 9.20%. The Loan Agreement required interest-only payments for 18 months, followed by an amortization period of 36 months. The original maturity date of the loan was August 1, 2021 and in February 2018 we signed an amendment with the lender which extended the maturity date by one year to August 1, 2022 with principal payments commencing on September 1, 2019. The expected remaining repayment of the $15 million loan principal at December 31, 2018 is as follows: 2019 $ 1,667 2020 5,000 2021 5,000 2022 3,333 $ 15,000 Upon the earlier of prepayment or the maturity date, we will pay to the Lender a final payment of 6% of the full principal amount of the loan. We may elect to prepay all amounts owed prior to the maturity date, provided that a prepayment fee also is paid equal to 1% of the full principal amount of the loan. Pursuant to the terms of the Loan Agreement, we are bound by certain affirmative covenants setting forth actions that are required during the term of the Loan Agreement, including, without limitation, certain information delivery requirements, obligations to maintain certain insurance, and certain notice requirements. Additionally, we are bound by certain negative covenants setting forth actions that are not permitted to be taken during the term of the Loan Agreement without consent, including, without limitation, incurring certain additional indebtedness, entering into certain mergers, acquisitions or other business combination transactions, or incurring any non-permitted lien or other encumbrance on our assets. We are in compliance with the loan covenants at December 31, 2018. Upon the occurrence of an event of default under the Loan Agreement (subject to cure periods for certain events of default), all amounts owed by us thereunder will begin to bear interest at a rate that is 5% higher than the rate that is otherwise applicable and may be declared immediately due and payable by the Lender. Events of default under the Loan Agreement include, among other things, the following: the occurrence of certain bankruptcy events; the failure to make payments under the Loan Agreement when due; the occurrence of a material adverse change in our business, operations or financial condition; the rendering of certain types of fines or judgments against us; any breach by us of any covenant (subject to cure for certain covenants only) made in the Loan Agreement; and the failure of any representation or warranty made by us in connection with the Loan Agreement to be correct in all material respects when made. We have granted Lender, a security interest in substantially all of our personal property, rights and assets, other than intellectual property, to secure the payment of all amounts owed to the Lender under the Loan Agreement. We have also agreed not to encumber any of our intellectual property without required lenders’ prior written consent. In connection with entering into the Loan Agreement, we issued to the Lender warrants to purchase an aggregate of 354,330 shares of our common stock (the “Lender Warrants”). The warrants are exercisable immediately, have a per-share exercise price of   $1.27 and have a term of ten years. We have recorded the relative fair value of the warrants as a discount to the carrying value of the notes payable with a corresponding increase to additional paid in capital. In February 2018, the Loan Agreement was amended requiring payments of interest on a monthly basis through August 2019 and payments of interest and principal from September 2019 to August 2022. In connection with entering into the amendment we issued to the Lender warrants to purchase an aggregate of 93,168 shares of our common stock. The warrants are exercisable immediately, have a per-share exercise price of   $1.61 and have a term of ten years. The amendment was determined a modification of debt according to ASC 470 Debt.

PREFERRED STOCK AND WARRANT LIA

PREFERRED STOCK AND WARRANT LIABILITY	12 Months Ended
	Dec. 31, 2018
Preferred Stock And Warrant Liability [Abstract]
PREFERRED STOCK AND WARRANT LIABILITY	9. PREFERRED STOCK AND WARRANT LIABILITY Our amended Certificate of Incorporation authorizes the issuance of up to 1 million shares of   $0.01 par value preferred stock. In November 2017, we entered into definitive securities purchase agreements with certain institutional investors. In conjunction with this stock offering we raised net proceeds of  $9.5 million through the sale of 8,370 shares of series A convertible preferred stock (Series A Preferred) and warrants covering 2,259 shares of Series A Preferred (Warrants). Each share of Series A Preferred converted into 1,000 shares of common stock and each associated Warrant converted into 1,000 common stock warrants upon the effectiveness on May 8, 2018 of an amendment to our restated certificate of incorporation to increase the number of authorized shares of common stock thereunder. The amount reported as preferred stock at December 31, 2018 is zero and at December 31, 2017 is $8.8 million. At December 31, 2017 the fair value of the warrant liability increased to $1.5 million and consequently a $0.9 million non-cash expense was recorded. The terms of the Series A Preferred, specifically the terms of the liquidation preference, required the classification of the preferred stock as temporary equity, which is reflected in our balance sheet as of December 31, 2017. In addition, the terms of the Series A Preferred for which the warrants are exercisable require that the fair value allocated to the warrants at the date of issuance be recorded as a liability. The warrant liability was marked to market value through the income statement as a non-cash gain or loss at each reporting period until the conversion of the preferred stock to common stock on May 8, 2018. The Warrants had a pre-conversion exercise price of  $1,750 per share of Series A Preferred (post-conversion price of  $1.75 per share of common stock), were exercisable immediately with an expiration date in May 2022. Upon conversion of the Series A Preferred common on May 8, 2018, the warrant liability of  $3,064 was extinguished with an offsetting amount included as additional paid-in capital in stockholders’ equity. At December 31, 2017 the fair value of the warrant liability was $1.5 million. In the year ended December 31, 2018 the fair value of the warrant liability increased by $1.5 million and non-cash expense was recorded in other expense. At December 31, 2018 the warrant liability was zero.

COMMON STOCK

COMMON STOCK	12 Months Ended
	Dec. 31, 2018
Common Stock [Abstract]
COMMON STOCK	10. COMMON STOCK Our amended Certificate of Incorporation authorizes the issuance of up to 200 million shares of common stock, par value $0.01 per share. At December 31, 2018, we have 4,610,616 shares reserved for future issuance of common stock options pursuant to the 2014 Equity Incentives Plan (“Equity Incentives Plan”). In July 2018, we sold 12,650,000 shares of common stock at $5.50 per share for aggregate net proceeds of approximately $64.6 million after commissions and other estimated offering expenses. In October 2017, we entered into definitive securities purchase agreements with certain institutional investors. In conjunction with this stock offering, we issued 13,938,651 shares of our common stock and warrants for 3,123,674 shares of our common stock for aggregate net proceeds of   $15.6 million. Each warrant is exercisable for $1.75 per share and expires in in October 2021. In September 2017, we sold 2.0 million shares of common stock through an at-the-market (ATM) offering and raised net proceeds of approximately $2.3 million. In February 2016, we entered into definitive stock purchase agreements with certain institutional and accredited investors. In conjunction with this stock offering we issued 8,027,900 shares of our common stock and non-transferable options for 3,567,956 shares of our common stock for aggregate net proceeds of $15.2 million. Each option was exercisable for $2.50 per share and they all expired in March 2017.

EQUITY INCENTIVE PLANS

EQUITY INCENTIVE PLANS	12 Months Ended
	Dec. 31, 2018
Disclosure Of Compensation Related Costs, Share-Based Payments [Abstract]
EQUITY INCENTIVE PLANS	11. EQUITY INCENTIVE PLANS In 2014, our stockholders approved our 2014 Equity Incentives Plan and authorized 3,750,000 shares of common stock for issuance pursuant to future awards under that 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 2014 Equity Incentives Plan may also be issued for future awards under the 2014 Equity Incentives Plan. In 2018, our stockholders approved an amendment to our 2014 Equity Incentives Plan to increase the number of shares of common stock available for issuance for issuance pursuant to future awards made under that plan by 3,750,000. 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 2014 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 2014 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, 2018, no stock appreciation rights have been issued. At December 31, 2018, there were 4,610,616 shares available for future grants under the 2014 Equity Incentives Plan. During 2014, our stockholders approved an amendment to the 1996 Director Stock Option Plan to increase the number of shares available to 1,200,000. Under the terms of the 1996 Director Stock Option 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 20,000 and vesting one year from the date of grant. All options granted pursuant to the 1996 Director Plan have a term of ten years with exercise prices equal to fair market value on the date of grant. At December 31, 2017, options to purchase 760,000 shares of common stock are outstanding and exercisable under the 1996 Director Plan which terminated in 2016. Additionally, under the 2014 Equity Incentives Plan options issued to Directors to purchase 425,000 shares of common stock are outstanding at December 31, 2018 of which 260,000 are exercisable. Option activity under the Plans for the year ended December 31, 2018 was as follows: Stock Options Number of Shares Weighted Average Exercise Price Outstanding as of December 31, 2017 10,622,455 $ 3.01 Granted 1,911,770 2.78 Exercised (1,104,706 ) 3.22 Cancelled (681,362 ) 3.71 Outstanding as of December 31, 2018 10,748,157 $ 2.90 Exercisable as of December 31, 2018 5,973,658 $ 3.71 The following table summarizes information about options outstanding at December 31, 2018: Options Outstanding Options Exercisable Range of Exercise Prices Number December 31, 2018 Weighted Average Contractual Life Weighted Average Exercise Price Exercisable as of December 31, 2018 Weighted Average Exercise Price $0.95–1.41 2,352,567 7.46 $ 1.05 753,988 $ 1.17  1.42–2.35 3,329,745 7.71 1.69 1,234,325 1.71  2.36–3.80 2,636,207 4.96 2.73 2,001,207 2.80  3.81–5.60 626,750 7.07 4.81 186,250 4.12  5.61–8.40 1,802,888 2.56 7.13 1,797,888 7.13 10,748,157 6.08 $ 2.90 5,973,658 $ 3.71 The aggregate intrinsic value of options outstanding at December 31, 2018 was $8,112. The weighted average grant date fair value of options granted in year ended December 31, 2018, 2017 and 2016 was $1.73, $0.72, and $1.10, per share, respectively. In the year ended December 31, 2018 we had 1,104,706 options were exercised. In the year ended December 31, 2017 no options were exercised. Options vested, expected to vest and exercisable at December 31, 2018 are as follows: Options Weighted-Average Weighted-Average Aggregate Vested and unvested expected to vest at December 31, 2018 10,560,209 $ 2.90 6.08 $ 8,112 Exercisable at December 31, 2018 5,973,658 $ 3.71 4.26 $ 2,823 The total compensation cost not yet recognized as of December 31, 2018 related to non-vested option awards was $3,951 which will be recognized over a weighted-average period of 2.7 years. During the year ended December 31, 2018, 251,275 shares were forfeited with a weighted average grant date fair value of $0.81 per share and a weighted average exercise price of $1.36 per share. During the year ended December 31, 2018, 430,087 shares expired with a weighted average grant date fair value of $2.82 per share and a weighted average exercise price of $5.08 per share. The weighted average remaining contractual life for options exercisable at December 31, 2018 was 4.3 years. In April 2017, we amended our chief executive officer’s (the “CEO’s”) and chief operating officer’s (the “COO’s”) employment agreements to extend the term and also granted them a maximum of 600,000 and 300,000 performance-based stock options, respectively, that vest upon the achievement of certain performance and market-based targets. In April 2017, we amended our chief medical officer’s (the “CMO’s”) employment agreement to extend the term and also granted him 260,000 performance-based stock options that vest upon the achievement of certain performance-based targets. In April 2017, certain other employees were granted a total of 270,000 performance-based stock options that vest upon the achievement of certain performance-based targets 110,000 of these options were forfeited in 2018. Through December 31, 2018 no expense has been recorded for any performance-based stock options granted to the CEO, COO, CMO, or to any other employees. In 1996, the stockholders adopted the 1996 Employee Stock 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 1996 Employee Stock 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 1996 Employee Stock 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 our common stock that may be issued to 2,400,000. As of December 31, 2017, 2,217,705 shares have been purchased and no shares are available under this plan which was terminated in 2016. In 2018, the stockholders adopted the 2018 Employee Stock 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 2018 Employee Stock Purchase Plan are granted by the Board of Directors. We recognized share-based compensation expense related to the 1996 Employee Stock Purchase Plan of  $12, $17 and $60 for the year ended December 31, 2018, 2017 and 2016, respectively.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	12. INCOME TAXES There was no current or deferred tax expense for the years ended December 31, 2018, 2017 or 2016 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, 2018, 2017 and 2016: 2018 2017 2016 Income tax (benefit) expense at statutory rate $ (3,251 ) $ (9,929 ) $ (7,724 ) State tax (benefit) expense, net of Federal tax (benefit) expense (938 ) (1,452 ) (1,146 ) Permanent items 75 508 263 Effect of change in valuation allowance and State NOL expiration 4,542 (39,972 ) 8,837 Tax credits (132 ) (544 ) (228 ) Change in tax rate on beginning assets — 51,445 — Other (296 ) (56 ) (2 ) 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, 2018 and 2017: 2018 2017 Deferred tax assets: Net operating loss carryforwards $ 103,855 $ 100,421 Tax credit carryforwards 26,880 26,771 Equity based compensation 4,361 3,381 Book depreciation in excess of tax 56 49 Reserves and accruals 178 171 Other 21 16 135,351 130,809 Valuation allowance (135,351 ) (130,809 ) Deferred tax liabilities — — Net deferred tax assets $ — $ — Total valuation allowance increased by $4,542 for the year ended December 31, 2018, decreased by $39,972 for the year ended December 31, 2017 and increased by $8,837 for the year ended December 31, 2016. 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, 2018. The Tax Cuts and Jobs Act was enacted on December 22, 2017. The Act reduced the US federal corporate tax rate from 35% to 21%, required companies to re-measure the deferred tax assets and deferred tax liabilities as of the date of enactment. In the year ended December 31, 2017, we re-measured deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future, which is generally 21%. The amount recorded related to the re-measurement of our deferred tax balance before Valuation Allowance was $51,445 which was offset by the full valuation allowance in the year ended December 31, 2017. We determined for the year ended December 31, 2018 that no further adjustment was necessary. As of December 31, 2018, we had federal NOL, state NOL, and research and development credit carryforwards of approximately $422,045, $240,916 and $28,378 respectively, which expire at various dates through 2037. Out of the total federal NOL of  $422,045, $12,636 of NOL generated in 2018 has an indefinite life. As of December 31, 2018, and 2017 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, 2018 and 2017, we had no accrued interest or penalties related to uncertain tax positions. Our U.S. federal tax returns for the tax years 2015 through 2018 and our state tax returns for the tax years 2015 through 2018 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, 2019, 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.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	13. 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 2019 $ 523 2020 296 Thereafter — Total minimum lease payments $ 819 Rent expense under our non-cancelable operating lease was approximately $554, $546, and $540 for the years ended December 31, 2018, 2017 and 2016, respectively. In January 2015, we entered into a lease agreement for our 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, 2018
Risks and Uncertainties [Abstract]
CONCENTRATION OF CREDIT RISK	14. CONCENTRATION OF CREDIT RISK Revenue from one customer represented approximately 72% of total revenue during 2018 and revenue from another customer represented approximately 23% of total revenue. There were no revenues recognized in 2017. Revenue from one customer represented approximately 40% of total revenue during 2016 and revenue from another customer represented approximately 60% of total revenue.

SELECTED QUARTERLY FINANCIAL DA

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED)	15. SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) FIRST SECOND THIRD FOURTH 2018 Net revenues $ 4,138 $ 13,706 $ 4,979 $ 2,941 Net income (loss) (6,532 ) 5,156 (5,619 ) (8,487 ) Basic and diluted net income (loss) per share: Basic net income (loss) per share $ (0.07 ) $ 0.06 $ (0.05 ) $ (0.08 ) Diluted net income (loss) per share $ (0.07 ) $ 0.05 $ (0.05 ) $ (0.08 ) FIRST SECOND THIRD FOURTH 2017 Net revenues $ — $ — $ — $ — Net loss (7,576 ) (7,201 ) (6,666 ) (7,760 ) Basic and diluted net loss per share: Net loss per share $ (0.11 ) $ (0.10 ) $ (0.09 ) $ (0.09 )

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	12 Months Ended
	Dec. 31, 2018
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. We classify our investments as either current or long-term based upon the investments’ contractual maturities and our 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, 2018 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, 2018, 2017 or 2016. 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 Measurements	Fair Value Measurements Certain of our assets are carried at fair value under U.S. generally accepted accounting principles (GAAP). Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. Financial assets and liabilities carried at fair value are to be classified and disclosed in one of the following three levels of the fair value hierarchy, of which the first two are considered observable and the last is considered unobservable: • Level 1—Quoted prices in active markets for identical assets or liabilities. • Level 2—Observable inputs (other than Level 1 quoted prices), such as quoted prices in active markets for similar assets or liabilities, quoted prices in markets that are not active for identical or similar assets or liabilities, or other inputs that are observable or can be corroborated by observable market data. • Level 3—Unobservable inputs that are supported by little or no market activity that are significant to determining the fair value of the assets or liabilities, including pricing models, discounted cash flow methodologies and similar techniques. At December 31, 2018 and 2017 our financial instruments consisted of cash, cash equivalents, investments in corporate debt securities, accounts payable, notes payable and accrued expenses. At December 31, 2018 and 2017, our financial instruments also included marketable securities which are reported at fair value. At December 31, 2017 our financial instruments also included warrant liabilities reported at fair value. The warrant liability was carried at fair value and determined to be a Level 3 liability in the fair value hierarchy described above. The carrying values of cash, cash equivalents, investments in corporate debt securities, marketable securities, accounts payable and accrued expenses approximate their fair values due to the short-term nature of these assets and liabilities. The carrying value of our notes payable approximates their fair value.
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, 2018, 2017 and 2016 was $46, $65 and $101, 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 and license 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. Our policy is to recognize revenues when our customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. We recognize revenues following the five step model prescribed under Accounting Standards Codification Topic 606—Revenue from Contracts with Customers. Under Topic 606 we: (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenues when (or as) we satisfy the performance obligation. We only apply the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, we assess the goods or services promised within each contract, and determine those that are performance obligations. The transaction price is allocated to the identified performance obligations in proportion to their estimated standalone selling prices (SSP) on a relative basis. Determining the estimated SSP for performance obligations requires judgment. In developing the SSP for a performance obligation, we consider applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. Revenue is recognized when each distinct performance obligation is satisfied. For certain performance obligations that are satisfied over time we recognize revenue using the cost-to-cost method. Under the cost-to-cost method, the extent of progress towards completion is measured based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the identified performance obligation. Under this method, revenue will be recorded as a percentage of the estimated transaction price based on the extent of progress towards completion. Incurred cost represents work performed, which corresponds with, and thereby best depicts, the transfer of control to the customer. Due to the nature of the work performed in these arrangements, the estimation of cost at completion is subject to many variables and requires judgment. Circumstances can arise that change original estimates of costs or progress toward completion. Changes to the estimated cost at completion have not had a material impact on the results of operations.
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.
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 14 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 (Expense)	Other Income (Expense) Other income (expense) in 2018 includes a non-cash expense of  $1,552 from an increase in fair value of our preferred stock warrant liability. The preferred stock warrant liability was eliminated upon the conversion of the preferred shares into common shares in the year ended December 31, 2018. Other income (expense) in 2017 includes a non-cash expense of  $902 from an increase in fair value of our preferred stock warrant liability. Other income (expense) was $0 in 2016.
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, we recognize the benefit of uncertain tax positions in the financial statements.
Earnings (Loss) Per Share	Earnings (Loss) Per Share Net loss per share is computed using the weighted average number of common shares outstanding. Basic and diluted net loss per share amounts are equivalent for the periods presented as the inclusion of potential common shares in the number of shares used for the diluted computation would be anti-dilutive to loss per share. Potential common shares, for the year ended December 31, 2018, include 10,748,157 shares that would be issued upon the exercise of outstanding employee and Board of Director stock options, 93,168 shares that would be issued upon the exercise of the warrants from the February 2018 amendment to our loan agreement, 3,123,674 shares that would be issued upon the exercise of the warrants from our October 2017 common stock offering, and 2,259,000 common shares that would be issued upon the exercise of the warrants from our November 2017 preferred stock offering. The shares and warrants from our November 2017 preferred stock offering were converted on May 8, 2018 to common shares and warrants. Potential common shares, for the year ended December 31, 2017, include 10,622,455 shares that would be issued upon the exercise of outstanding employee and Board of Director stock options, 354,330 shares that would be issued upon the exercise of the warrants from our January 2017 loan agreement, 3,123,674 shares that would be issued upon the exercise of the warrants from our October 2017 common stock offering, 8,370,000 common shares that would be issued upon the conversion of the shares from our November 2017 preferred stock offering and 2,259,000 common shares that would be issued upon the exercise of the warrants from our November 2017 preferred stock offering. Potential common shares for the year ended December 31, 2016, include 8,715,048 shares that would be issued upon the exercise of outstanding employee and Board of Director stock options and options to purchase 3,567,956 shares that would have been issued upon the exercise of the options from our February 2016 common stock offering. The options issued in conjunction with the February 2016 common stock offering expired in 2017.
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, 2018, 2017 and 2016 included in our Statements of Operations and Comprehensive Loss: 2018 2017 2016 Research and development $ 369 $ 359 $ 514 General and administrative 1,134 1,075 1,351 Total stock-based compensation expense $ 1,503 $ 1,434 $ 1,865 In the years ended December 31, 2018, 2017 and 2016, 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, 2018, 2017 and 2016 respectively were estimated on the grant date using the Black-Scholes option-pricing model with the following assumptions: 2018 2017 2016 Dividend yield(1) 0.0% 0.0% 0.0% Weighted average expected volatility factor(2) 62% 62% 63% Risk free interest(3) 2.4–2.9% 1.9–2.1% 1.2–1.8% Expected term, excluding options issued pursuant to the Employee Stock Purchase Plan(4) 5.6–7.2 years 6.1–7.1 years 5.8–7.2 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 us 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 May 2017 the FASB issued Accounting Standard Update (“ASU”) No. 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting. This new standard provides clarity and reduces both (1) diversity in practice and (2) cost and complexity when applying the guidance in Topic 718, Compensation-Stock Compensation, to a change to the terms or conditions of a share-based payment award. This new standard became effective for us on January 1, 2018. The adoption of this standard did not have a material impact on our financial position or results of operations. In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments. This new standard clarifies certain aspects of the statement of cash flows, including the classification of debt prepayment or debt extinguishment costs or other debt instruments with coupon interest rates that are insignificant in relation to the effective interest rate of the borrowing, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of corporate-owned life insurance policies, distributions received from equity method investees and beneficial interests in securitization transactions. This new standard also clarifies that an entity should determine each separately identifiable source of use within the cash receipts and payments on the basis of the nature of the underlying cash flows. In situations in which cash receipts and payments have aspects of more than one class of cash flows and cannot be separated by source or use, the appropriate classification should depend on the activity that is likely to be the predominant source or use of cash flows for the item. This new standard became effective for us on January 1, 2018. The adoption of this standard did not have a material impact on our statements of cash flows upon adoption. In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The new standard involves several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. We adopted this ASU in 2017 and it did not have a material impact on our financial position, results of operations or statement of cash flows. In February 2016 the FASB issued ASU No. 2016-02, Leases (Topic 842). This standard established a right-of-use model that requires all lessees to recognize right-of-use assets and liabilities on their balance sheet that arise from leases with terms longer than 12 months as well as provide disclosures with respect to certain qualitative and quantitative information related to their leasing arrangements. This standard became effective for us on January 1, 2019. The FASB has subsequently issued the following amendments to ASU 2016-02, which have the same effective date and transition date of January 1, 2019, and which we collectively refer to as the new leasing standards: • ASU No. 2018-01, Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842, which permits an entity to elect an optional transition practical expedient to not evaluate under Topic 842 land easements that exist or expired prior to adoption of Topic 842 and that were not previously accounted for as leases under the prior standard, ASC 840, Leases. • ASU No. 2018-10, Codification Improvements to Topic 842, Leases, which amends certain narrow aspects of the guidance issued in ASU 2016-02. • ASU No. 2018-11, Leases (Topic 842): Targeted Improvements, which allows for a transition approach to initially apply ASU 2016-02 at the adoption date and recognize a cumulative-effect adjustment to the opening balance of accumulated deficit in the period of adoption as well as an additional practical expedient for lessors to not separate non-lease components from the associated lease component. • ASU No. 2018-20, Narrow-Scope Improvements for Lessors, which contains certain narrow scope improvements to the guidance issued in ASU 2016-02. We adopted the new leasing standards on January 1, 2019, using a modified retrospective transition approach to be applied to leases existing as of, or entered into after, January 1, 2019. We have reviewed our existing lease contracts and the impact of the new leasing standards on our results of operations, financial position and disclosures. Upon adoption of the new leasing standards, we expect to recognize a lease liability and related right-of-use asset on our balance sheet of approximately $0.7 million. We expect that the impact of adoption of the new leasing standards will not have a material impact on our statement of income. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes (Topic 740), which requires that deferred tax liabilities and assets be classified as noncurrent in a classified statement of financial position to simplify the presentation of deferred income taxes. This new standard became effective for us on January 1, 2017 and did not have a material impact on our disclosures. In May 2014 the FASB issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers (Topic 606), which supersedes all existing revenue recognition requirements, including most industry specific guidance. The FASB subsequently issued amendments to ASU No. 2014-09 that have the same effective date and transition date. This standard requires a company to recognize revenues 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. Under the new revenue standards, we recognize revenues when our customer obtains control of promised goods or services, in an amount that reflects the consideration which we expect to receive in exchange for those goods or services. We recognize revenues following the five-step model prescribed under Topic 606: (i) identify contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenues when (or as) we satisfy the performance obligation. We only apply the five-step model to contracts when it is probable that the entity will collect the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, we assess the goods or services promised within each contract, and determines those that are performance obligations. The transaction price is allocated to the identified performance obligations in proportion to their estimated standalone selling prices (SSP) on a relative basis. Determining the estimated SSP for performance obligations requires judgment. In developing the SSP for a performance obligation, we consider applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the customer and estimated costs. Revenue is recognized when each distinct performance obligation is satisfied. For certain performance obligations that are satisfied over time the we recognize revenue using the cost-to-cost method. Under the cost-to-cost method, the extent of progress towards completion is measured based on the ratio of actual costs incurred to the total estimated costs expected upon satisfying the identified performance obligation. Under this method, revenue will be recorded as a percentage of the estimated transaction price based on the extent of progress towards completion. Incurred cost represents work performed, which corresponds with, and thereby best depicts, the transfer of control to the customer. Due to the nature of the work performed in these arrangements, the estimation of cost at completion is subject to many variables and requires judgment. Circumstances can arise that change original estimates of costs or progress toward completion. Changes to the estimated cost at completion have not had a material impact on the results of operations. We adopted Accounting Standards Codification Topic 606—Revenue from Contracts with Customers, or Topic 606, on January 1, 2018, using the modified retrospective approach and resulted in a change to its accounting policy for revenue recognition. Results for reporting periods beginning after January 1, 2018 are presented under the new standard, while prior period amounts are not adjusted and continue to be reported under the accounting standards in effect for the prior period. We recorded a net increase to opening equity of  $1.5 million as of January 1, 2018 due to the cumulative impact of adopting this new standard. Without applying the new revenue standard, the disclosed research and development revenue would have been $1.4 million higher than currently disclosed for the year ended December 31, 2018. Contract receivables were $6.0 million at December 31, 2018. The adoption of the new revenue standard did not have a material impact on any other balances within the financial statements as of and for the year ended December 31, 2018. However, the adoption of the new revenue standards will result in a change in the timing of revenue recognition related to certain of our licensing agreements based upon the terms of the underlying agreements.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of stock-based compensation expense	2018 2017 2016 Research and development $ 369 $ 359 $ 514 General and administrative 1,134 1,075 1,351 Total stock-based compensation expense $ 1,503 $ 1,434 $ 1,865
Schedule of fair value of stock options and employee stock purchase plan under the Black-Scholes option-pricing model	2018 2017 2016 Dividend yield(1) 0.0% 0.0% 0.0% Weighted average expected volatility factor(2) 62% 62% 63% Risk free interest(3) 2.4–2.9% 1.9–2.1% 1.2–1.8% Expected term, excluding options issued pursuant to the Employee Stock Purchase Plan(4) 5.6–7.2 years 6.1–7.1 years 5.8–7.2 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 FAI_2

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS (Tables)	12 Months Ended
	Dec. 31, 2018
Marketable Securities and Fair Value Measurements [Abstract]
Schedule of fair value of available-for-sale marketable securities	December 31, 2018 Amortized Cost Gross Gains Gross Losses Fair Value Security type Corporate debt securities-short term $ 80,417 $ 2 $ (97 ) $ 80,322 Total available-for-sale marketable securities $ 80,417 $ 2 $ (97 ) $ 80,322 December 31, 2017 Amortized Cost Gross Gains Gross Losses Fair Value Security type Corporate debt securities-short term $ 27,823 $ 1 $ (17 ) $ 27,807 Total available-for-sale marketable securities $ 27,823 $ 1 $ (17 ) $ 27,807
Schedule of assets and liabilities that are measured at fair value on recurring basis	December 31, Quoted Prices in Significant Significant Cash equivalents $ 14,444 $ 14,444 $ — $ — Corporate debt securities-short term 80,322 — 80,322 — Total $ 94,766 $ 14,444 $ 80,322 $ — December 31, Quoted Prices in Significant Significant Cash equivalents $ 19,889 $ 19,889 $ — $ — Corporate debt securities-short term 27,807 — 27,807 — Total $ 47,696 $ 19,889 $ 27,807 $ — December 31, Quoted Prices in Significant Significant Warrant liability $ 1,512 $ — $ — $ 1,512
Schedule of warrant liability	2017 Warrant stock price $1.75 Exercise price 1.65 Expected volatility 53.3% Risk-free interest 2.07% Expected term 3.85 years Dividends none
Schedule of fair value of our warrant liability	Amount Warrant liability as of December 31, 2017 $ 1,512 Change in fair value 1,552 Conversion of preferred stock warrants to common stock warrants (3,064 ) Warrant liability as of December 31, 2018 $ —

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule of property and equipment	USEFUL 2018 2017 Machinery and equipment 5 $ 1,611 $ 1,939 Leasehold improvements 3–5 232 232 Furniture and fixtures 7 40 40 Computer equipment 3 2,496 2,497 4,379 4,708 Less: Accumulated depreciation and amortization 4,310 4,593 Net property and equipment $ 69 $ 115

OTHER ASSETS (Tables)

OTHER ASSETS (Tables)	12 Months Ended
	Dec. 31, 2018
Other Assets [Abstract]
Schedule of other assets	2018 2017 Security deposits $ 204 $ 204 Total other assets $ 204 $ 204

ACCOUNTS PAYABLE AND ACCRUED _2

ACCOUNTS PAYABLE AND ACCRUED EXPENSES (Tables)	12 Months Ended
	Dec. 31, 2018
Payables and Accruals [Abstract]
Schedule of accounts payable and accrued expenses	2018 2017 Accounts payable $ 1,329 $ 537 Accrued payroll 1,971 1,448 Accrued outsourced preclinical and clinical fees 8,497 5,409 Accrued professional fees 666 492 Other accrued expenses 485 373 $ 12,948 $ 8,259

LOAN AGREEMENT (Tables)

LOAN AGREEMENT (Tables)	12 Months Ended
	Dec. 31, 2018
Long-term Debt, Unclassified [Abstract]
Schedule of expected remaining repayment	2019 $ 1,667 2020 5,000 2021 5,000 2022 3,333 $ 15,000

EQUITY INCENTIVE PLANS (Tables)

EQUITY INCENTIVE PLANS (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2017 10,622,455 $ 3.01 Granted 1,911,770 2.78 Exercised (1,104,706 ) 3.22 Cancelled (681,362 ) 3.71 Outstanding as of December 31, 2018 10,748,157 $ 2.90 Exercisable as of December 31, 2018 5,973,658 $ 3.71
Schedule of options outstanding	Options Outstanding Options Exercisable Range of Exercise Prices Number December 31, 2018 Weighted Average Contractual Life Weighted Average Exercise Price Exercisable as of December 31, 2018 Weighted Average Exercise Price $0.95–1.41 2,352,567 7.46 $ 1.05 753,988 $ 1.17  1.42–2.35 3,329,745 7.71 1.69 1,234,325 1.71  2.36–3.80 2,636,207 4.96 2.73 2,001,207 2.80  3.81–5.60 626,750 7.07 4.81 186,250 4.12  5.61–8.40 1,802,888 2.56 7.13 1,797,888 7.13 10,748,157 6.08 $ 2.90 5,973,658 $ 3.71
Schedule of options vested, expected to vest and exercisable	Options Weighted-Average Weighted-Average Aggregate Vested and unvested expected to vest at December 31, 2018 10,560,209 $ 2.90 6.08 $ 8,112 Exercisable at December 31, 2018 5,973,658 $ 3.71 4.26 $ 2,823

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of company's effective income tax rate	2018 2017 2016 Income tax (benefit) expense at statutory rate $ (3,251 ) $ (9,929 ) $ (7,724 ) State tax (benefit) expense, net of Federal tax (benefit) expense (938 ) (1,452 ) (1,146 ) Permanent items 75 508 263 Effect of change in valuation allowance and State NOL expiration 4,542 (39,972 ) 8,837 Tax credits (132 ) (544 ) (228 ) Change in tax rate on beginning assets — 51,445 — Other (296 ) (56 ) (2 ) Tax expense (benefit) $ — $ — $ —
Schedule of company's deferred tax assets and deferred tax liabilities	2018 2017 Deferred tax assets: Net operating loss carryforwards $ 103,855 $ 100,421 Tax credit carryforwards 26,880 26,771 Equity based compensation 4,361 3,381 Book depreciation in excess of tax 56 49 Reserves and accruals 178 171 Other 21 16 135,351 130,809 Valuation allowance (135,351 ) (130,809 ) Deferred tax liabilities — — Net deferred tax assets $ — $ —

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of minimum lease commitment for our leased facility	YEAR ENDING DECEMBER 31, OPERATING LEASES 2019 $ 523 2020 296 Thereafter — Total minimum lease payments $ 819

SELECTED QUARTERLY FINANCIAL _2

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of unaudited quarterly financial data	FIRST SECOND THIRD FOURTH 2018 Net revenues $ 4,138 $ 13,706 $ 4,979 $ 2,941 Net income (loss) (6,532 ) 5,156 (5,619 ) (8,487 ) Basic and diluted net income (loss) per share: Basic net income (loss) per share $ (0.07 ) $ 0.06 $ (0.05 ) $ (0.08 ) Diluted net income (loss) per share $ (0.07 ) $ 0.05 $ (0.05 ) $ (0.08 ) FIRST SECOND THIRD FOURTH 2017 Net revenues $ — $ — $ — $ — Net loss (7,576 ) (7,201 ) (6,666 ) (7,760 ) Basic and diluted net loss per share: Net loss per share $ (0.11 ) $ (0.10 ) $ (0.09 ) $ (0.09 )

ORGANIZATION AND NATURE OF OP_2

ORGANIZATION AND NATURE OF OPERATIONS (Detail Textuals) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended								12 Months Ended
	Jul. 31, 2018	Apr. 30, 2018	Feb. 28, 2018	Nov. 30, 2017	Oct. 31, 2017	Sep. 30, 2017	Jan. 31, 2017	Feb. 29, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Organization and nature of operations
Net use of cash									$ (12,976)	$ (25,175)	$ (22,937)
Proceeds from stock offering	$ 64,600					$ 2,300			$ 64,561	$ 17,951	$ 15,174
Number of stock issued	12,650,000					2,000,000
Share price	$ 5.50
Definitive stock purchase agreements
Organization and nature of operations
Proceeds from stock offering								$ 15,200
Number of stock issued					13,938,651			8,027,900
Proceeds from sale of common stock					$ 15,600
Number of warrants issued to purchase common stock					3,123,674
Exercise price of warrants or rights					$ 1.75
Definitive stock purchase agreements | Series A convertible preferred stock and warrants
Organization and nature of operations
Proceeds from stock offering				$ 9,500
Definitive stock purchase agreements | Series A convertible preferred stock
Organization and nature of operations
Number of stock issued				8,370
Number of common stock issued upon conversion				1,000
Definitive stock purchase agreements | Series A Preferred Warrants
Organization and nature of operations
Number of stock issued				2,259
Number of common stock issued upon conversion				1,000
Post-conversion price of common stock				$ 1.75
Oxford Finance, LLC | Loan Agreement
Organization and nature of operations
Loan principal amount							$ 15,000
Period of interest rate payments							18 months
Amortization period							36 months
Maturity date			Aug. 1, 2022				Aug. 1, 2021
Sinovant Sciences Ltd | Sinovant Sciences Ltd licensing agreement
Organization and nature of operations
Upfront payment			$ 3,000
Additional development milestone			2,500
Regulatory sales and commercial milestones			$ 82,000
Basilea Pharmaceutica Limited (Basilea) | Basilea pharmaceutical limited licensing agreement
Organization and nature of operations
Upfront payment		$ 10,000
Regulatory sales and commercial milestones		$ 326,000

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Stock-based compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,503	$ 1,434	$ 1,865
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	369	359	514
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,134	$ 1,075	$ 1,351

SUMMARY OF SIGNIFICANT ACCOUN_5

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	[1]	5 years 7 months 6 days	6 years 1 month 6 days	5 years 9 months 18 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term	[1]	7 years 2 months 12 days	7 years 1 month 6 days	7 years 2 months 12 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]	62.00%	62.00%	63.00%
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]	2.40%	1.90%	1.20%
Employee stock purchase plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest	[5]	2.90%	2.10%	1.80%
[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 ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Detail Textuals) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)Segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Accounting Policies [Abstract]
Depreciation method	straight-line method
Depreciation and amortization expense	$ 46	$ 65	$ 101
Number of operating segments | Segment	1
Other income (expense)	$ 1,552	$ 902	$ 0

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Detail Textuals 1) - Stock Options - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Exercise of outstanding employee and Board of Director 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	10,748,157	10,622,455	8,715,048
Exercise of warrants from February 2018 amendment to loan agreement
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	93,168
Exercise of warrants from January 2017 loan agreement
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		354,330
Exercise of warrants from October 2017 common stock offering
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	3,123,674	3,123,674
Conversion of shares from November 2017 preferred stock offering
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		8,370,000
Exercise of warrants from November 2017 preferred stock offering
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	2,259,000	2,259,000
Exercise of options from February 2016 common stock offering
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			3,567,956

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Detail Textuals 2) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Accounting Policies [Abstract]
Cumulative impact for accounting changes to recognize a lease liability	$ 0.7
Cumulative impact for accounting changes net increase to opening equity	1.5
Cumulative impact for accounting changes in revenues	1.4
Contract receivables included in prepaid expenses and other current assets	$ 6

COLLABORATIONS AND ALLIANCES (D

COLLABORATIONS AND ALLIANCES (Detail Textuals) - USD ($) $ in Millions	1 Months Ended		12 Months Ended
	Apr. 30, 2018	Feb. 28, 2018	Dec. 31, 2018	Dec. 31, 2017
Basilea Licensing Agreement | Basilea Pharmaceutica International Limited
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Regulatory sales and commercial milestones	$ 326
Upfront payment paid in the first quarter of 2019	$ 10
Research and development revenue			$ 18.5
Sinovant License Agreement | Sinovant
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Regulatory sales and commercial milestones		$ 82
Upfront payment paid in the first quarter of 2019		3
Research and development revenue			0.4
Additional development milestone paid in the first quarter of 2019		$ 2.5
Revenue			5.9
Other Licensing Agreements
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue for completing performance obligation			$ 1.3
Deferred revenue				$ 1.5

MARKETABLE SECURITIES AND FAI_3

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS - Summary of fair value of available-for-sale securities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 80,417	$ 27,823
Gross Unrealized Gains	2	1
Gross Unrealized Losses	(97)	(17)
Fair Value	80,322	27,807
Corporate debt securities | Short term
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	80,417	27,823
Gross Unrealized Gains	2	1
Gross Unrealized Losses	(97)	(17)
Fair Value	$ 80,322	$ 27,807

MARKETABLE SECURITIES AND FAI_4

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS - Assets measured at fair value on a recurring basis (Details 1) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability	$ 0	$ 1,512
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	14,444	19,889
Corporate debt securities-short term	80,322	27,807
Total	94,766	47,696
Warrant liability		1,512
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	14,444	19,889
Corporate debt securities-short term	0	0
Total	14,444	19,889
Warrant liability		0
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	0	0
Corporate debt securities-short term	80,322	27,807
Total	80,322	27,807
Warrant liability		0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Corporate debt securities-short term	0	0
Total	$ 0	0
Warrant liability		$ 1,512

MARKETABLE SECURITIES AND FAI_5

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS - Warrant liability valuation (Details 2)	Dec. 31, 2017USD_pershare
Warrant stock price
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Warrants input	1.75
Exercise price
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Warrants input	1.65
Expected volatility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Warrants input	53.3
Risk-free interest
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Warrants input	2.07
Expected term
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Expected term	3 years 10 months 6 days
Dividends
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Warrants input	0

MARKETABLE SECURITIES AND FAI_6

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Fair Value Of Warrant Liability [Roll Forward]
Warrant liability	$ 1,512
Change in fair value	1,552	$ 902
Conversion of preferred stock warrants to common stock warrants	(3,064)
Warrant liability	$ 0	$ 1,512

MARKETABLE SECURITIES AND FAI_7

MARKETABLE SECURITIES AND FAIR VALUE MEASUREMENTS (Detail Textuals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Marketable Securities and Fair Value Measurements [Abstract]
Valuation method	Black-Scholes model
Warrant liability	$ 0	$ 1,512
Warrant liability extinguished	$ 3,064

PROPERTY AND EQUIPMENT - Proper

PROPERTY AND EQUIPMENT - Property and equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4,379	$ 4,708
Less: Accumulated depreciation and amortization	4,310	4,593
Net property and equipment	$ 69	115
Machinery and equipment
Property, Plant and Equipment [Line Items]
USEFUL LIFE ESTIMATED (YEARS)	5 years
Property and equipment, gross	$ 1,611	1,939
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 232	232
Leasehold improvements | Minimum
Property, Plant and Equipment [Line Items]
USEFUL LIFE ESTIMATED (YEARS)	3 years
Leasehold improvements | Maximum
Property, Plant and Equipment [Line Items]
USEFUL LIFE ESTIMATED (YEARS)	5 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
USEFUL LIFE ESTIMATED (YEARS)	7 years
Property and equipment, gross	$ 40	40
Computer equipment
Property, Plant and Equipment [Line Items]
USEFUL LIFE ESTIMATED (YEARS)	3 years
Property and equipment, gross	$ 2,496	$ 2,497

OTHER ASSETS - Components of Ot

OTHER ASSETS - Components of Other assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Other Assets, Noncurrent [Abstract]
Security deposits	$ 204	$ 204
Total other assets	$ 204	$ 204

ACCOUNTS PAYABLE AND ACCRUED _3

ACCOUNTS PAYABLE AND ACCRUED EXPENSES - Summary of accounts payable and accrued expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Accounts payable	$ 1,329	$ 537
Accrued payroll	1,971	1,448
Accrued outsourced preclinical and clinical fees	8,497	5,409
Accrued professional fees	666	492
Other accrued expenses	485	373
Accounts payable and accrued expenses, Total	$ 12,948	$ 8,259

LOAN AGREEMENT (Details)

LOAN AGREEMENT (Details) $ in Thousands	Dec. 31, 2018USD ($)
Long-term Debt, Unclassified [Abstract]
2,019	$ 1,667
2,020	5,000
2,021	5,000
2,022	3,333
Loan principal amount	$ 15,000

LOAN AGREEMENT (Detail Textuals

LOAN AGREEMENT (Detail Textuals) - Oxford Finance, LLC - Loan Agreement - USD ($) $ / shares in Units, $ in Millions	1 Months Ended		12 Months Ended
	Feb. 28, 2018	Jan. 31, 2017	Dec. 31, 2018
Debt Instrument [Line Items]
Loan principal amount		$ 15
Interest rate description		<div>(a) the greater of (i) the 30 day U.S. LIBOR rate reported in the Wall Street Journal on the date occurring on the last business day of the month that immediately precedes the month in which the interest will accrue or (ii) 0.65% (b) plus 6.85%.</div>
Interest rate		0.65%
Basis spread interest rate		6.85%
Applicable interest rate			9.20%
Period of interest rate payments		18 months
Amortization period		36 months
Maturity date	Aug. 1, 2022	Aug. 1, 2021
Percentage of final principal payment		6.00%
Percentage of prepayment fee		1.00%
Additional interest rate after default		5.00%
Term of payment of interest after amendment	Monthly basis through August 2019
Term of payment of interest and principal after amendment	From September 2019 to August 2022
Lender Warrants
Debt Instrument [Line Items]
Number of warrants issued to purchase common stock	93,168	354,330
Pre-share exercise price of warrants or rights	$ 1.61	$ 1.27
Exercise term of warrants or rights	10 years	10 years

PREFERRED STOCK AND WARRANT L_2

PREFERRED STOCK AND WARRANT LIABILITY (Detail Textuals) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended					12 Months Ended
	Jul. 31, 2018	Nov. 30, 2017	Oct. 31, 2017	Sep. 30, 2017	Feb. 29, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Preferred Stock And Warrant Liability [Line Items]
Series A Preferred stock, shares authorized						1,000,000	1,000,000
Series A Preferred stock, par value (in dollars per share)						$ 0.01	$ 0.01
Proceeds from stock offering	$ 64,600			$ 2,300		$ 64,561	$ 17,951	$ 15,174
Number of stock issued	12,650,000			2,000,000
Change in fair value of warrant liability						1,552	902
Non-cash expense						900
Warrant liability extinguished						3,064
Warrant liability						0	1,500
Definitive stock purchase agreements
Preferred Stock And Warrant Liability [Line Items]
Proceeds from stock offering					$ 15,200
Number of stock issued			13,938,651		8,027,900
Definitive stock purchase agreements | Series A convertible preferred stock and warrants
Preferred Stock And Warrant Liability [Line Items]
Proceeds from stock offering		$ 9,500
Amount reported as preferred stock						$ 0	$ 8,800
Definitive stock purchase agreements | Series A convertible preferred stock
Preferred Stock And Warrant Liability [Line Items]
Number of stock issued		8,370
Number of common stock issued upon conversion		1,000
Definitive stock purchase agreements | Series A Preferred Warrants
Preferred Stock And Warrant Liability [Line Items]
Number of stock issued		2,259
Number of common stock issued upon conversion		1,000
Warrants, pre-conversion exercise price		$ 1,750
Post-conversion price of common stock		$ 1.75

COMMON STOCK (Detail Textuals)

COMMON STOCK (Detail Textuals) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended				12 Months Ended
	Jul. 31, 2018	Oct. 31, 2017	Sep. 30, 2017	Feb. 29, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Common Stock [Line Items]
Common stock, shares authorized					200,000,000	200,000,000
Common stock, par value (in dollars per share)	$ 5.50				$ 0.01	$ 0.01
Number of common stock issued under agreement	12,650,000		2,000,000
Proceeds from stock offering	$ 64,600		$ 2,300		$ 64,561	$ 17,951	$ 15,174
2014 Equity Incentives Plan | Stock Options
Common Stock [Line Items]
Number of shares available for grant					4,610,616
Definitive stock purchase agreements
Common Stock [Line Items]
Number of common stock issued under agreement		13,938,651		8,027,900
Number of warrants issued to purchase common stock		3,123,674
Proceeds from Issuance of Common Stock		$ 15,600
Exercise price		$ 1.75
Proceeds from stock offering				$ 15,200
Number of non transferable options issued				3,567,956
Aggregate net proceeds				$ 15,200
Stock option exercise price				$ 2.50

EQUITY INCENTIVE PLANS - Option

EQUITY INCENTIVE PLANS - Option activity (Details) - Equity Incentive Plan - Stock Options	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Number of Shares
Outstanding as of December 31, 2017 | shares	10,622,455
Granted | shares	1,911,770
Exercised | shares	(1,104,706)
Cancelled | shares	(681,362)
Outstanding as of December 31, 2018 | shares	10,748,157
Exercisable as of December 31, 2018 | shares	5,973,658
Weighted Average Exercise Price
Outstanding as of December 31, 2017 | $ / shares	$ 3.01
Granted | $ / shares	2.78
Exercised | $ / shares	3.22
Cancelled | $ / shares	3.71
Outstanding as of December 31, 2018 | $ / shares	2.90
Exercisable as of December 31, 2018 | $ / shares	$ 3.71

EQUITY INCENTIVE PLANS - Summar

EQUITY INCENTIVE PLANS - Summary of options outstanding (Details 1) - Equity Incentive Plan - Stock Options - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options Outstanding at December 31, 2018	10,748,157	10,622,455
Options Outstanding, Weighted Average Remaining Contractual Life	6 years 29 days
Options Outstanding, Weighted Average Exercise Price	$ 2.90	$ 3.01
Options Exercisable as of December 31, 2018	5,973,658
Options Exercisable, Weighted Average Exercise Price	$ 3.71
Range of Exercise Prices : $ 0.95 - 1.41
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Lower Limit	0.95
Range of Exercise Prices, Upper Limit	$ 1.41
Number of Options Outstanding at December 31, 2018	2,352,567
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 5 months 16 days
Options Outstanding, Weighted Average Exercise Price	$ 1.05
Options Exercisable as of December 31, 2018	753,988
Options Exercisable, Weighted Average Exercise Price	$ 1.17
Range of Exercise Prices : $ 1.42 - 2.35
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Lower Limit	1.42
Range of Exercise Prices, Upper Limit	$ 2.35
Number of Options Outstanding at December 31, 2018	3,329,745
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 8 months 16 days
Options Outstanding, Weighted Average Exercise Price	$ 1.69
Options Exercisable as of December 31, 2018	1,234,325
Options Exercisable, Weighted Average Exercise Price	$ 1.71
Range of Exercise Prices : $ 2.36 - 3.80
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Lower Limit	2.36
Range of Exercise Prices, Upper Limit	$ 3.80
Number of Options Outstanding at December 31, 2018	2,636,207
Options Outstanding, Weighted Average Remaining Contractual Life	4 years 11 months 16 days
Options Outstanding, Weighted Average Exercise Price	$ 2.73
Options Exercisable as of December 31, 2018	2,001,207
Options Exercisable, Weighted Average Exercise Price	$ 2.80
Range of Exercise Prices : $ 3.81 - 5.60
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Lower Limit	3.81
Range of Exercise Prices, Upper Limit	$ 5.60
Number of Options Outstanding at December 31, 2018	626,750
Options Outstanding, Weighted Average Remaining Contractual Life	7 years 26 days
Options Outstanding, Weighted Average Exercise Price	$ 4.81
Options Exercisable as of December 31, 2018	186,250
Options Exercisable, Weighted Average Exercise Price	$ 4.12
Range of Exercise Prices : $ 5.61 - 8.40
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Range of Exercise Prices, Lower Limit	5.61
Range of Exercise Prices, Upper Limit	$ 8.40
Number of Options Outstanding at December 31, 2018	1,802,888
Options Outstanding, Weighted Average Remaining Contractual Life	2 years 6 months 22 days
Options Outstanding, Weighted Average Exercise Price	$ 7.13
Options Exercisable as of December 31, 2018	1,797,888
Options Exercisable, Weighted Average Exercise Price	$ 7.13

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, 2018USD ($)$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vested and unvested expected to vest, Options | shares	10,560,209
Vested and unvested expected to vest, weighted-average exercise price | $ / shares	$ 2.90
Vested and unvested expected to vest, weighted-average remaining contractual term (in years)	6 years 29 days
Vested and unvested expected to vest, aggregate intrinsic value | $	$ 8,112
Exercisable, Options | shares	5,973,658
Exercisable, weighted-average exercise price | $ / shares	$ 3.71
Exercisable, weighted-average remaining contractual term (in years)	4 years 3 months 4 days
Exercisable, aggregate intrinsic value | $	$ 2,823

EQUITY INCENTIVE PLANS (Detail

EQUITY INCENTIVE PLANS (Detail Textuals) - 2014 Equity Incentives Plan - Stock Options - shares	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2018
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		4,610,616

EQUITY INCENTIVE PLANS (Detai_2

EQUITY INCENTIVE PLANS (Detail Textuals 1) - 1996 Director Stock Option Plan - Stock Options - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2014	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized		1,200,000
Options granted term		10 years
Options to purchase shares of common stock	760,000
Number of options outstanding			425,000
Number of shares exercisable			260,000
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		20,000
Award vesting period for re - election		1 year

EQUITY INCENTIVE PLANS (Detai_3

EQUITY INCENTIVE PLANS (Detail Textuals 2) - Equity Incentive Plan - Stock Options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate intrinsic value of options outstanding	$ 8,112
Weighted average grant date fair value of options granted	$ 1.73	$ 0.72	$ 1.10
Number of options exercised	1,104,706
Compensation cost not yet recognized for non-vested option awards	$ 3,951
Compensation cost related to non-vested option awards recognition period	2 years 8 months 12 days
Number of the non-vested options forfeited during the period	251,275
Weighted average grant date fair value of the options non vested which are forfeited during the period	$ 0.81
Weighted average exercise price of the options non vested which are forfeited during the period	$ 1.36
Number of the non-vested options shares expired during period	430,087
Weighted average grant date fair value of non-vested options expired during period	$ 2.82
Weighted average exercise price of non-vested options expired during the period	$ 5.08
Weighted average remaining contractual life for options exercisable	4 years 3 months 18 days

EQUITY INCENTIVE PLANS (Detai_4

EQUITY INCENTIVE PLANS (Detail Textuals 3) - Employment agreement - Performance-based stock options - shares	1 Months Ended	12 Months Ended
	Apr. 30, 2017	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance-based stock options share forfeited		110,000
Chief executive officer (CEO)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	600,000
Chief operating officer (COO)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	300,000
Chief medical officer (CMO)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	260,000
Other employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted	270,000

EQUITY INCENTIVE PLANS (Detai_5

EQUITY INCENTIVE PLANS (Detail Textuals 4) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 1,503	$ 1,434	$ 1,865
Stock Options | 1996 Employee Stock 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 exercisable period	27 months
Number of shares authorized				2,400,000
Number of shares purchased		2,217,705
Share-based compensation expense	$ 12	$ 17	$ 60

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, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax (benefit) expense at statutory rate	$ (3,251)	$ (9,929)	$ (7,724)
State tax (benefit) expense, net of Federal tax (benefit) expense	(938)	(1,452)	(1,146)
Permanent items	75	508	263
Effect of change in valuation allowance and State NOL expiration	4,542	(39,972)	8,837
Tax credits	(132)	(544)	(228)
Change in tax rate on beginning assets	0	51,445	0
Other	(296)	(56)	(2)
Tax expense (benefit)	$ 0	$ 0	$ 0

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, 2018	Dec. 31, 2017
Deferred tax assets:
Net operating loss carryforwards	$ 103,855	$ 100,421
Tax credit carryforwards	26,880	26,771
Equity based compensation	4,361	3,381
Book depreciation in excess of tax	56	49
Reserves and accruals	178	171
Other	21	16
Deferred tax assets, gross	135,351	130,809
Valuation allowance	(135,351)	(130,809)
Deferred tax liabilities	0	0
Net deferred tax assets	$ 0	$ 0

INCOME TAXES (Detail Textuals)

INCOME TAXES (Detail Textuals) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Amount of valuation allowance increase (decrease)	$ 4,542	$ 39,972	$ 8,837
Deferred tax balance before valuation allowance	0	$ 51,445	$ 0
Net operating loss carryforwards	$ 12,636
Increase in ownership percentage of certain stockholders or public groups	more than 50 percentage points
Ownership change, increase in ownership percentage, term	3 years
Earliest tax year
Operating Loss Carryforwards [Line Items]
US federal corporate tax rate	35.00%
Latest tax year
Operating Loss Carryforwards [Line Items]
US federal corporate tax rate	21.00%
Federal income tax
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 422,045
State income tax
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	240,916
Research and development credit carryforwards
Operating Loss Carryforwards [Line Items]
Net operating loss carryforwards	$ 28,378

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Minimum lease commitments for all leased facilities, net of sublease income (Details) $ in Thousands	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,019	$ 523
2,020	296
Thereafter	0
Total minimum lease payments	$ 819

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES (Detail Textuals) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Commitments And Contingencies Disclosure [Line Items]
Rent expense under non-cancelable operating leases		$ 554	$ 546	$ 540
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, 2018	Dec. 31, 2016
Customer One
Concentration Risk [Line Items]
Percentage of total sales accounted	72.00%	40.00%
Customer Two
Concentration Risk [Line Items]
Percentage of total sales accounted	23.00%	60.00%

SELECTED QUARTERLY FINANCIAL _3

SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) - Quarterly financial data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Net revenues	$ 2,941	$ 4,979	$ 13,706	$ 4,138	$ 0	$ 0	$ 0	$ 0	$ 25,764		$ 4,709
Net income (loss)	$ (8,487)	$ (5,619)	$ 5,156	$ (6,532)	$ (7,760)	$ (6,666)	$ (7,201)	$ (7,576)	$ (15,482)	$ (29,203)	$ (22,718)
Basic and diluted net income (loss) per share:
Basic net income (loss) per share (in dollars per share)	$ (0.08)	$ (0.05)	$ 0.06	$ (0.07)
Diluted net income (loss) per share (in dollars per share)	$ (0.08)	$ (0.05)	$ 0.05	$ (0.07)
Net loss per share (in dollars per share)					$ (0.09)	$ (0.09)	$ (0.1)	$ (0.11)	$ (0.16)	$ (0.39)	$ (0.33)