Iovance Biotherapeutics (IOVA) 10-K 28 Feb 19 2018 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 13, 2019	Jun. 30, 2018
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Entity Registrant Name	IOVANCE BIOTHERAPEUTICS, INC.
Entity Central Index Key	1,425,205
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 1,125,017,562
Trading Symbol	IOVA
Entity Common Stock, Shares Outstanding		123,420,091
Entity Shell Company	false
Entity Emerging Growth Company	false
Entity Small Business	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 82,152	$ 145,373
Short-term investments	386,371	0
Prepaid expenses and other assets	6,851	3,917
Total Current Assets	475,374	149,290
Property and equipment, net	2,683	2,450
Long-term assets	2,764	3,633
Total Assets	480,821	155,373
Current Liabilities
Accounts payable	2,739	1,232
Accrued expenses	11,659	8,363
Total Current Liabilities	14,398	9,595
Non-Current Liabilities
Deferred rent	230	297
Total Non-Current Liabilities	230	297
Total Liabilities	14,628	9,892
Commitments and contingencies (Note 11)
Stockholders' Equity
Common stock, $0.000041666 par value; 150,000,000 shares authorized, 123,415,576 and 73,164,914 shares issued and outstanding as of December 31, 2018 and December 31, 2017, respectively	5	3
Accumulated other comprehensive loss	(42)	0
Additional paid-in capital	838,984	394,651
Accumulated deficit	(372,760)	(249,180)
Total Stockholders' Equity	466,193	145,481
Total Liabilities and Stockholders' Equity	480,821	155,373
Series A Convertible Preferred stock [Member]
Stockholders' Equity
Preferred stock,Value	0	0
Total Stockholders' Equity	0	0
Series B Convertible Preferred stock [Member]
Stockholders' Equity
Preferred stock,Value	6	7
Total Stockholders' Equity	$ 6	$ 7

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Common Stock, Par or Stated Value Per Share	$ 0.000041666	$ 0.000041666
Common Stock, Shares Authorized	150,000,000	150,000,000
Common Stock, Shares, Issued	123,415,576	73,164,914
Common Stock, Shares, Outstanding	123,415,576	73,164,914
Series A Convertible Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Preferred Stock, Shares Authorized	17,000	17,000
Preferred Stock, Shares Issued	194	1,694
Preferred Stock, Shares Outstanding	194	1,694
Preferred Stock, Redemption Amount	$ 194	$ 194
Series B Convertible Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Preferred Stock, Shares Authorized	11,500,000	11,500,000
Preferred Stock, Shares Issued	5,854,845	7,378,241
Preferred Stock, Shares Outstanding	5,854,845	7,378,241
Preferred Stock, Redemption Amount	$ 27,811	$ 27,811

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues	$ 0	$ 0	$ 0
Costs and expenses
Research and development expenses	99,828	71,615	26,941
General and administrative expenses	28,430	21,262	26,698
Total costs and expenses	128,258	92,877	53,639
Loss from operations	(128,258)	(92,877)	(53,639)
Other income
Interest income, net	4,678	813	745
Net Loss	(123,580)	(92,064)	(52,894)
Deemed dividend related to beneficial conversion feature of convertible preferred stock	0	0	(49,454)
Net Loss Attributable to Common Stockholders	$ (123,580)	$ (92,064)	$ (102,348)
Net Loss Per Common Share, Basic and Diluted	$ (1.27)	$ (1.41)	$ (1.85)
Weighted-Average Common Share Outstanding, Basic and Diluted	97,277	65,242	55,268

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net Loss	$ (123,580)	$ (92,064)	$ (52,894)
Other comprehensive loss:
Net unrealized loss on short-term investments	(42)	(29)	(19)
Comprehensive Loss	$ (123,622)	$ (92,093)	$ (52,913)

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Series A Convertible Preferred Stock [Member]	Series B Convertible Preferred Stock [Member]
Beginning Balance at Dec. 31, 2015	$ 104,023	$ 2	$ 208,195	$ 48	$ (104,222)	$ 0	$ 0
Beginning Balance (in Shares) at Dec. 31, 2015		48,547,720				1,694	0
Stock-based compensation expense	18,904		18,904
Tax payments related to shares witheld for vested restricted stock awards	(642)		(642)
Common stock issued upon exercise of warrants	1,235	$ 0	1,235
Common stock issued upon exercise of warrants (in Shares)		592,132
Common stock issued upon exercise of stock options	626		626
Common stock issued upon exercise of stock options (in shares)		100,480
Common stock sold in private placement, net of offering costs	44,009	$ 1	44,008
Common stock sold in private placement, net of offering costs (in shares)		9,684,000
Preferred stock sold in private placement, net of offering costs	51,676		51,665				$ 11
Preferred stock sold in private placement, net of offering costs (in shares)							11,368,633
Vesting of restricted shares issued for services	0		0
Conversion of convertible preferred stock into common stock	0		3				$ (3)
Conversion of convertible preferred stock into common stock (in Shares)		3,421,960					(3,421,960)
Cancellation of resticted shares	0	$ 0
Cancellation of resticted shares (in Shares)		(98,218)
Beneficial conversion feature of preferred stock	(49,454)		(49,454)
Deemed dividend on beneficial conversion feature of preferred stock	49,454		49,454
Unrealized loss on short- term investments	(19)			(19)
Net loss	(52,894)				(52,894)
Ending Balance at Dec. 31, 2016	166,918	$ 3	323,994	29	(157,116)	$ 0	$ 8
Ending Balance (in Shares) at Dec. 31, 2016		62,248,074				1,694	7,946,673
Stock-based compensation expense	11,968		11,968
Tax payments related to shares witheld for vested restricted stock awards	(1,252)	$ 0	(1,252)
Common stock issued upon exercise of warrants	662	$ 0	662
Common stock issued upon exercise of warrants (in Shares)		265,000
Common stock issued upon exercise of stock options	5,616	$ 0	5,616
Common stock issued upon exercise of stock options (in shares)		1,011,284
Common stock sold in public offering, net of offering costs	53,662	$ 0	53,662
Common stock sold in public offering, net of offering costs (in shares)		8,846,154
Vesting of restricted shares issued for services	0	$ 0	0
Vesting of restricted shares issued for services (in shares)		225,970
Conversion of convertible preferred stock into common stock	0		1				$ (1)
Conversion of convertible preferred stock into common stock (in Shares)		568,432					(568,432)
Unrealized loss on short- term investments	(29)			(29)
Net loss	(92,064)				(92,064)
Ending Balance at Dec. 31, 2017	145,481	$ 3	394,651	0	(249,180)	$ 0	$ 7
Ending Balance (in Shares) at Dec. 31, 2017		73,164,914				1,694	7,378,241
Stock-based compensation expense	20,027		20,027
Tax payments related to shares witheld for vested restricted stock awards	(223)		(223)
Common stock issued upon exercise of warrants	15,754	$ 1	15,753
Common stock issued upon exercise of warrants (in Shares)		6,301,216
Common stock issued upon exercise of stock options	9,959		9,959
Common stock issued upon exercise of stock options (in shares)		1,336,514
Common stock sold in public offering, net of offering costs	398,817	$ 1	398,816
Common stock sold in public offering, net of offering costs (in shares)		40,300,000
Vesting of restricted shares issued for services	0	$ 0
Vesting of restricted shares issued for services (in shares)		45,833
Conversion of convertible preferred stock into common stock	0	$ 0	1			$ 0	$ (1)
Conversion of convertible preferred stock into common stock (in Shares)		2,273,396				(1,500)	(1,523,396)
Cancellation of resticted shares	0	$ 0
Cancellation of resticted shares (in Shares)		(6,297)
Unrealized loss on short- term investments	(42)			(42)
Net loss	(123,580)				(123,580)
Ending Balance at Dec. 31, 2018	$ 466,193	$ 5	$ 838,984	$ (42)	$ (372,760)	$ 0	$ 6
Ending Balance (in Shares) at Dec. 31, 2018		123,415,576				194	5,854,845

Consolidated Statements of Cash

Consolidated 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	$ (123,580)	$ (92,064)	$ (52,894)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	956	952	978
Loss on disposal of assets	9	0	0
Accretion (amortization) of discounts and premiums on investments	(1,332)	19	(74)
Stock-based compensation expense	20,027	11,968	18,904
Changes in assets and liabilities:
Prepaid expenses and other assets	(2,065)	(4,508)	(2,765)
Accounts payable	1,507	369	(250)
Accrued expenses	3,229	4,555	3,433
Net cash used in operating activities	(101,249)	(78,709)	(32,668)
Cash Flows from Investing Activities
Maturities of short-term investments	41,000	59,705	120,664
Purchase of short-term investments	(426,081)	0	(110,249)
Purchase of property and equipment	(1,198)	(1,028)	(1,521)
Net cash (used in) provided by investing activities	(386,279)	58,677	8,894
Cash Flows from Financing Activities
Tax payments related to shares withheld for vested restricted stock awards	(223)	(1,252)	(642)
Proceeds from the issuance of common stock upon exercise of warrants	15,754	662	1,235
Proceeds from the issuance of common stock upon exercise of options	9,959	5,616	626
Proceeds from the issuance of preferred stock and common stock, net	398,817	53,662	95,685
Net cash provided by financing activities	424,307	58,688	96,904
Net (decrease) increase in cash and cash equivalents	(63,221)	38,656	73,130
Cash and Cash Equivalents, Beginning of Period	145,373	106,717	33,587
Cash and Cash Equivalents, End of Period	82,152	145,373	106,717
Supplemental disclosure of cash flow information:
Cash paid for income taxes	0	0	0
Interest paid	0	0	0
Supplemental disclosure of non-cash investing and financing activities:
Net unrealized loss on short-term investments	(42)	(29)	(19)
Acquisitions of property and equipment included in accounts payable	0	0	155
Offering costs under accounts payable and accrued expenses	0	0	49,454
Conversion of convertible preferred stock to common stock	$ 1	$ 1	$ 3

GENERAL ORGANIZATION, BUSINESS

GENERAL ORGANIZATION, BUSINESS AND LIQUIDITY	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
GENERAL ORGANIZATION, BUSINESS AND LIQUIDITY	NOTE 1. GENERAL ORGANIZATION, BUSINESS AND LIQUIDITY General Organization and Business Iovance Biotherapeutics, Inc. (the “Company”) is a clinical-stage biopharmaceutical company focused on the development and commercialization of novel cancer immunotherapy products designed to harness the power of a patient’s own immune system to eradicate cancer cells. The Company’s lead product candidate, lifileucel (formerly known as LN144) for metastatic melanoma, is an autologous adoptive cell therapy utilizing TIL, which are T cells derived from patients’ tumors. therapy utilizing TIL for the treatment of cancers other than metastatic melanoma The Company is investigating the effectiveness and safety of TIL therapy for the treatment of metastatic melanoma, squamous cell carcinoma of the head and neck, cervical cancer, and metastatic non-small cell lung cancer through company sponsored trials, as well as other oncology indications. On June 1, 2017, the Company reincorporated to become a company governed by Delaware corporation laws. Liquidity The Company is currently engaged in the development of therapeutics to fight cancer, specifically solid tumors. The Company currently does not have any commercial products and has not yet generated any revenues from its business. The Company currently does not anticipate that it will generate any revenues from the sale or licensing of any of its product candidates during the 12 months from the date these financial statements are issued. The Company has incurred a net loss of $123.6 million for the year ended December 31, 2018 and used $101.2 million of cash in its operating activities during the year ended December 31, 2018. In January 2018, the Company closed an underwritten public offering of 15,000,000 shares of the Company’s common stock at a public offering price of $11.50 per share, before underwriting discounts, which included 1,956,521 shares issued upon the exercise in full by the underwriter of its option to purchase additional shares at the public offering price less the underwriting discount. The net proceeds from the offering, after deducting the underwriting discounts and commissions and other offering expenses payable by the Company, were $162.0 million. On October 17, 2018, the Company completed an underwritten public offering of 25,300,000 shares of the Company’s common stock at a public offering price of $9.97 per share, before underwriting discounts, which included 3,300,000 shares issued upon the exercise in full by the underwriter of its option to purchase additional shares at the public offering price less the underwriting discount. The net proceeds from the offering, after deducting the underwriting discounts and commissions and other offering expenses payable by the Company, were $236.7 million. As of December 31, 2018, the Company had $82.2 million of cash and cash equivalents and $386.4 million in short-term investments. The Company expects to further increase its research and development activities, which will increase the amount of cash used during 2019 and beyond. Specifically, the Company expects continued spending on its current and planned clinical trials, continued expansion of manufacturing activities, including construction of a manufacturing facility, higher payroll expenses as the Company increases its professional and scientific staff, increased research and development activities and initiation of pre-commercial activities. Based on the funds the Company has available as of the date these financial statements are issued, the Company believes that it has sufficient capital to fund its anticipated operating expenses for at least next twelve months from the date these financial statements are issued. Concentrations of Risk The Company is subject to credit risk from our portfolio of cash equivalents and short-term investments. Under its investment policy, the Company limits amounts invested in such securities by credit rating, maturity, industry group, investment type and issuer, except for securities issued by the U.S. government. The Company does not believe it is exposed to any significant concentrations of credit risk from these financial instruments. The goals of its investment policy, in order of priority, are as follows: safety and preservation of principal and diversification of risk; liquidity of investments sufficient to meet cash flow requirements; and a competitive after-tax rate of return.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES	NOTE 2. SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES Cash, Cash Equivalents, and Short-term Investments The Company’s cash and cash equivalents include short-term investments with original maturities of three months or less when purchased. The Company's short-term investments are classified as “available-for-sale”. The Company includes these investments in current assets and carries them at fair value. Unrealized gains and losses on available-for-sale securities are included in accumulated other comprehensive loss. The cost of debt securities is adjusted for the amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in net interest income in the consolidated statements operations. Gains and losses on securities sold are recorded based on the specific identification method and are included in net interest income in the consolidated statement of operations. The Company has not incurred any realized gains or losses from sales of securities to date. The Company’s investment policy limits investments to certain types of instruments such as certificates of deposit, money market instruments, obligations issued by the U.S. government and U.S. government agencies as well as corporate debt securities, and places restrictions on maturities and concentration by type and issuer. Property and Equipment, net Property and equipment is stated at cost, net of accumulated depreciation and amortization. The cost of property and equipment is depreciated or amortized on the straight-line method over the following estimated useful lives: Computer equipment 2 years Office furniture and equipment 5 years Lab equipment 5 years Leasehold improvements Lesser of the remaining economic life of the asset or the lease-term Expenditures for maintenance and repairs are charged to operations as incurred while renewals and betterments are capitalized. Gains and losses on disposals are included within operating expenses in the statements of operations. Management assesses the carrying value of property and equipment whenever events or changes in circumstances indicate that the carrying value may not be recoverable. If there is indication of impairment, management prepares an estimate of future undiscounted cash flows expected to result from the use of the asset and its eventual disposition. If these cash flows are less than the carrying amount of the asset, an impairment loss is recognized to write down the asset to its estimated fair value. For the years ended December 31, 2018, 2017 and 2016, the Company did not recognize any impairments for its property and equipment. Loss per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of shares of common stock outstanding and the dilutive common stock equivalent shares outstanding during the period. The Company’s potentially dilutive common stock equivalent shares, which include incremental common shares issuable upon (i) the exercise of outstanding stock options and warrants (ii) vesting of restricted stock units and restricted stock awards, and (iii) conversion of preferred stock, are only included in the calculation of diluted net loss per share when their effect is dilutive. At December 31, 2018, 2017 and 2016, the following outstanding common stock equivalents have been excluded from the calculation of net loss per share because their impact would be anti-dilutive. As of December 31, 2018 2017 2016 Stock options 6,889,287 6,072,368 6,233,150 Warrants - 6,301,216 6,566,216 Series A Convertible Preferred* 97,000 847,000 847,000 Series B Convertible Preferred* 5,854,845 7,378,241 7,946,673 Restricted stock awards - - 7,084 Restricted stock units 68,742 114,582 550,000 12,909,874 20,713,407 22,150,123 *on an as-converted basis The dilutive effect of potentially dilutive securities would be reflected in diluted earnings per common share by application of the treasury stock method. Under the treasury stock method, an increase in the fair market value of the Company's common stock could result in a greater dilutive effect from potentially dilutive securities. Fair Value Measurements Under Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 820, Fair Value Measurements and Disclosures, fair value is defined as the price at which an asset could be exchanged, or a liability transferred in a transaction between knowledgeable, willing parties in the principal or most advantageous market for the asset or liability. Where available, fair value is based on observable market prices or parameters or derived from such prices or parameters. Where observable prices or parameters are not available, valuation models are applied. Assets and liabilities recorded at fair value in the Company’s financial statements are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels directly related to the amount of subjectivity associated with the inputs to fair valuation of these assets and liabilities, are as follows: Level 1—Inputs are unadjusted, quoted prices in active markets for identical assets at the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2—Are inputs, other than quoted prices included in Level 1, that are either directly or indirectly observable for the asset or liability through correlation with market data at the reporting date and for the duration of the instrument’s anticipated life. The fair valued assets the Company holds that are generally assessed under Level 2 are corporate bonds and commercial paper. The Company utilizes third party pricing services in developing fair value measurements where fair value is based on valuation methodologies such as models using observable market inputs, including benchmark yields, reported trades, broker/dealer quotes, bids, offers and other reference data. The Company uses quotes from external pricing service providers and other on-line quotation systems to verify the fair value of investments provided by its third-party pricing service providers. The Company reviews independent service auditor’s reports from its third-party pricing service providers particularly regarding the controls over pricing and valuation of financial instruments and ensure that its internal controls address certain control deficiencies, if any, and complementary user entity controls are in place. The Company does not have fair valued assets classified under Level 2 as of December 31, 2018 and 2017. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities and which reflect management’s best estimate of what market participants would use in pricing the asset or liability at the reporting date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. The Company’s financial instruments consist of cash and cash equivalents, short-term investments, and accounts payable, all of which are reported at their respective fair value on its consolidated balance sheets. The Company does not have fair valued assets classified under Level 3 as of December 31, 2018 and 2017. As of December 31, 2018, financial assets measured at fair value on a recurring basis are categorized in the table below based upon the lowest level of significant input to the valuations (in thousands): Assets at Fair Value as of December 31, 2018 Level 1 Level 2 Level 3 Total US treasury securities $ 265,393 $ - $ - $ 265,393 US government agency securities 120,978 - - 120,978 Total $ 386,371 $ - $ - $ 368,371 As of December 31, 2017, the Company had no financial assets measured at fair value on a recurring basis. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. Significant estimates include valuation of short-term investments, the useful lives of property and equipment, accounting for potential liabilities, the valuation allowance associated with the Company’s deferred tax assets, and the assumptions made in valuing stock instruments issued for services. Principles of Consolidation The accompanying consolidated financial statements include the accounts of Iovance Biotherapeutics, Inc. and its wholly-owned subsidiary, Iovance Biotherapeutics GmbH (formerly Lion Biotechnologies GmbH). All intercompany accounts and transactions have been eliminated. The U.S. dollar is the functional currency for all the Company's consolidated operations. Stock-Based Compensation The Company periodically grants stock options and warrants to employees and non-employees in non-capital raising transactions as compensation for services rendered. The Company accounts for stock option grants to employees based on the authoritative guidance provided by the FASB where the value of the award is measured on the date of grant and recognized over the vesting period. The Company accounts for stock option grants to non-employees in accordance with the authoritative guidance of the FASB where the value of the stock compensation is determined based upon the measurement date at either a) the date at which a performance commitment is reached, or b) at the date at which the necessary performance to earn the equity instruments is complete. Non-employee stock-based compensation charges generally are amortized over the vesting period on a straight-line basis. In certain circumstances where there are no future performance requirements by the non-employee, option grants are immediately vested, and the total stock-based compensation charge is recorded in the period of the measurement date. The fair value of the Company's common stock option grants is estimated using a Black-Scholes option pricing model, which uses certain assumptions related to risk-free interest rates, expected volatility, expected life of the common stock options, and future dividends. Compensation expense is recorded based upon the value derived from the Black-Scholes option pricing model. The assumptions used in the Black-Scholes option pricing model could materially affect compensation expense recorded in future periods. The Company has in the past issued restricted shares of its common stock for share-based compensation programs. The Company measures the compensation cost with respect to restricted shares issued to employees based upon the estimated fair value of the equity instruments at the date of the grant, which is recognized as an expense over the period during which an employee is required to provide services in exchange for the award. The fair value of restricted stock units is based on the closing price of the Company’s common stock on the grant date. Total stock-based compensation expense related to all of the Company’s stock-based awards was recorded on the statements of operations as follows (in thousands): Years Ended December 31, 2018 2017 2016 Research and development $ 9,305 $ 5,270 $ 3,267 General and administrative 10,722 6,698 15,637 Total stock-based compensation expenses $ 20,027 $ 11,968 $ 18,904 Total stock-based compensation broken down based on each individual instrument was as follows (in thousands): Years Ended December 31, 2018 2017 2016 Stock option expense $ 19,758 $ 10,862 $ 16,453 Restricted stock award expense - 34 989 Restricted stock unit expense 269 1,072 1,462 Total stock-based compensation expenses $ 20,027 $ 11,968 $ 18,904 Research and Development Expenses Research and development expenses include personnel and facility-related expenses, outside contracted services including clinical trial costs, manufacturing and process development costs, research costs and other consulting services. Research and development costs are expensed as incurred. Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and amortized over the period that the goods are delivered, or the related services are performed, subject to an assessment of recoverability. Clinical development costs are a significant component of research and development expenses. The Company has a history of contracting with third parties that perform various clinical trial activities on its behalf in connection with the ongoing development of its product candidates. The financial terms of these contracts are subject to negotiations and may vary from contract to contract and may result in uneven payment flow. The Company accrues and expenses costs for clinical trial activities performed by third parties based upon estimates of the percentage of work completed over the life of the individual trial in accordance with agreements established with contract research organizations and clinical trial sites. The Company determines its estimates through discussions with internal clinical personnel and outside service providers as to the progress or stage of completion of trials or services and the agreed upon fee to be paid for such services. General and Administrative Expenses General and administrative expenses consist primarily of salaries and other related costs, including stock-based compensation, for personnel in executive, finance, accounting, legal, investor relations, facilities, business development and human resources functions. Other significant costs include facility costs not otherwise included in research and development expenses, sublicense royalty expenses, legal fees relating to corporate matters, insurance, public company expenses relating to maintaining compliance with Nasdaq listing rules and Securities and Exchange Commission (“SEC”) requirements, investor relations costs, and fees for accounting and consulting services. General and administrative costs are expensed as incurred, and the Company accrues for services provided by third parties related to the above expenses by monitoring the status of services provided and receiving estimates from its service providers and adjusting its accruals as actual costs become known. Income Taxes The Company accounts for income taxes using the asset and liability method whereby deferred tax assets are recognized for deductible temporary differences, and deferred tax liabilities are recognized for taxable temporary differences. Temporary differences are the differences between the reported amounts of assets and liabilities and their tax bases. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that some portion or all of the deferred tax assets will be realized. Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment. ASC Topic 740-10-30, Income Taxes, clarifies the accounting for uncertainty in income taxes recognized in an enterprise’s financial statements and prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. ASC Topic 740-10-40 provides guidance on de-recognition, classification, interest and penalties, accounting in interim periods, disclosure, and transition. The Company will classify as income tax expense any interest and penalties. The Company has no material uncertain tax positions for any of the reporting periods presented. Concentrations The Company is subject to credit risk from its portfolio of cash equivalents and short-term investments. Under its investment policy, it limits amounts invested in such securities by credit rating, maturity, industry group, investment type and issuer, except for securities issued by the U.S. government. The Company is not exposed to any significant concentrations of credit risk from these financial instruments. The goals of its investment policy, in order of priority, are as follows: safety and preservation of principal and diversification of risk; liquidity of investments sufficient to meet cash flow requirements; and a competitive after-tax rate of return. The Company maintains cash, cash equivalents and short-term investment balances at three financial institutions. At times, the amounts on deposit may exceed the federally insured limits. Management believes that the financial institutions which hold its cash are financially sound and, accordingly, minimal credit risk exists. As of December 31, 2018 and 2017, respectively, the Company’s cash balances were in excess of insured limits maintained at the financial institutions. Preferred Stock The Company applies the accounting standards for distinguishing liabilities from equity when determining the classification and measurement of its preferred stock. Preferred shares subject to mandatory redemption are classified as liability instruments and are measured at fair value. Conditionally redeemable preferred shares (including preferred shares that feature redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control) are classified as temporary equity. At all other times, preferred shares are classified as stockholders’ equity. Convertible Instruments The Company applies the accounting standards for derivatives and hedging and for distinguishing liabilities from equity when accounting for hybrid contracts that feature conversion options. The accounting standards require companies to bifurcate conversion options from their host instruments and account for them as free-standing derivative financial instruments according to certain criteria. The criteria include circumstances in which (i) the economic characteristics and risks of the embedded derivative instrument are not clearly and closely related to the economic characteristics and risks of the host contract, (ii) the hybrid instrument that embodies both the embedded derivative instrument and the host contract is not re-measured at fair value under otherwise applicable generally accepted accounting principles with changes in fair value reported in earnings as they occur and (iii) a separate instrument with the same terms as the embedded derivative instrument would be considered a derivative instrument. The derivative is subsequently marked to market at each reporting date based on current fair value, with the changes in fair value reported in results of operations. Conversion options that contain variable settlement features such as provisions to adjust the conversion price upon subsequent issuances of equity or equity linked securities at exercise prices more favorable than that featured in the hybrid contract generally result in their bifurcation from the host instrument. The Company also records, when necessary, deemed dividends for the intrinsic value of the conversion options embedded in preferred stock based upon the difference between the fair value of the underlying common stock at the commitment date of the transaction and the effective conversion price embedded in the preferred stock. Recently Issued Accounting Standards Not Yet Adopted In February 2016, the FASB issued Accounting Standard Update (ASU) No. 2016-02, Leases (Topic 842), which establishes a new lease accounting model for lessees. The updated guidance requires an entity to recognize assets and liabilities arising from a lease for both financing and operating leases, along with additional qualitative and quantitative disclosures. In June 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases, which further clarifies how to apply certain aspects of the new lease standard. Topic 842 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018, with early adoption permitted. The Company adopted Topic 842 on January 1, 2019, using a modified retrospective approach as applied to lease existing as of or entered into after the adoption date. Topic 842 provides a number of optional practical expedients and accounting policy elections. The Company elected the package of practical expedients requiring no reassessment of whether any expired or existing contracts are or contain leases, the lease classification of any expired or existing leases, or initial direct costs for any existing leases. The Company is in the final process of implementing a new lease accounting policy and updating its controls and procedures for maintaining and accounting for its lease portfolio under the new guidance. Upon adoption of Topic 842, the Company expects recognition of additional assets and corresponding liabilities pertaining to its operating leases on its consolidated balance sheets. The Company does not expect the adoption of the new standard to have a significant impact on its consolidated statements of operations and cash flows. In June 2018, the FASB issued ASU No. 2018-07, Compensation- Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, which eliminates the separate accounting model for nonemployee share-based payment awards and generally requires companies to account for share-based payment transactions with nonemployees in the same way as share-based payment transactions with employees. Under the new guidance, nonemployee share-based payment transactions are measured at the grant-date fair value and are no longer remeasured at the then-current fair values at each reporting date until the share options have vested. The amended guidance is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The Company plans to adopt this ASU on January 1, 2019. The guidance requires a modified-retrospective approach in transition. The Company compared the cumulative amounts that were recorded for its nonemployee share-based payments through December 31, 2018 immediately preceding the date of adoption to the cumulative amounts that should be recognized at the adoption date and will record a cumulative effect of the transition adjustment of $0.3 million as an adjustment to retained earnings as of the date of adoption, January 1, 2019. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework- Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates disclosure requirement regarding transfers between level 1 and level 2 of the fair value of hierarchy, however, adds disclosure requirements on the range and weighted average used to develop significant unobservable inputs for level 3 fair value measurements. The guidance is effective for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years, with early adoption permitted. The Company plans to adopt this ASU on January 1, 2020. The Company expects the impact of the adoption of this standard on its financial statements to be immaterial. In August 2018, the Security Exchange Commission (SEC) adopted the final rule under SEC Release No. 33-10532, “Disclosure Update and Simplification,” amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders’ equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders’ equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. This final rule is effective on November 5, 2018. The Company is evaluating the impact of this guidance on its consolidated financial statements. The Company anticipates its first presentation of changes in stockholders’ equity will be included in its Form 10-Q for the quarter ended March 31, 2019. Segment reporting The Company operates in one segment, focused on developing and commercializing ACT using autologous TIL for the treatment of metastatic melanoma and other solid cancers. Subsequent Events Management of the Company evaluates events that have occurred after the balance sheet date but before the financial statements are issued. Based upon the review, management did not identify any recognized or non-recognized subsequent events which would have required an adjustment or disclosure in the financial statements. Reclassifications Certain amounts within the balance sheets for the prior period have been reclassified to conform with the current period presentation. These reclassifications had no impact on the Company's previously reported financial position or cash flows for any of the periods presented. The long-term portion of deferred rent liability as of December 31, 2017 was separately presented as long-term in the 2017 consolidated balance sheet included in this annual report filed on Form10-K.

CASH AND CASH EQUIVALENTS, AND

CASH AND CASH EQUIVALENTS, AND SHORT-TERM INVESTMENTS	12 Months Ended
	Dec. 31, 2018
Cash, Cash Equivalents, and Short-term Investments [Abstract]
CASH AND CASH EQUIVALENTS AND SHORT-TERM INVESTMENTS	NOTE 3. CASH AND CASH EQUIVALENTS, AND SHORT-TERM INVESTMENTS Cash equivalents, and short-term investments consist of the following (in thousands): December 31, December 31, 2018 2017 Cash equivalents - Money market funds $ 25,968 $ 91,281 Cash equivalents total $ 25,968 $ 91,281 Cash equivalents in the tables above exclude cash demand deposits of $56.2 million and $54.1 million as of December 31, 2018 and December 31, 2017, respectively (in thousands). December 31, December 31, Short-term Investments 2018 2017 US treasury securities $ 265,393 $ - US government agency securities 120,978 - Short-term investments total $ 386,371 $ - The cost and fair value of cash equivalents and short-term investments at December 31, 2018 were as follows (in thousands): Gross Gross Unrealized Unrealized As of December 31, 2018 Cost Accretion Gains Losses Fair Value US treasury securities $ 264,619 $ 813 $ 19 $ (58 ) $ 265,393 US government agency securities 120,653 328 21 (24 ) 120,978 Total $ 385,272 $ 1,141 $ 40 $ (82 ) $ 386,371 As of December 31, 2017, the Company had no short-term investments. Unrealized gains and losses are included in accumulated other comprehensive loss. All short-term investments held by the Company as of December 31, 2018 have a maturity of less than one year.

BALANCE SHEET COMPONENTS

BALANCE SHEET COMPONENTS	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BALANCE SHEET COMPONENTS	NOTE 4. BALANCE SHEET COMPONENTS Property and equipment, net consists of the following (in thousands): December 31, December 31, 2018 2017 Lab equipment $ 4,160 $ 3,207 Leasehold improvements 1,776 1,726 Computer equipment 337 349 Office furniture and equipment 263 188 Construction in progress 107 13 Total Property and equipment, cost 6,643 5,483 Less: Accumulated depreciation and amortization (3,960 ) (3,033 ) property and equipment, net $ 2,683 $ 2,450 Depreciation expense for the years ended December 31, 2018, 2017 and 2016 was approximately $1.0 million, $1.0 million and $1.0 million, respectively. Accrued liabilities consist of the following (in thousands): December 31, December 31, 2018 2017 Accrued payroll and employee related expenses $ 4,113 $ 2,613 Legal and related services 825 935 Clinical related 3,424 3,310 Manufacturing related 2,684 876 Deferred rent - current 124 133 Accrued other 489 496 $ 11,659 $ 8,363

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
STOCKHOLDERS' EQUITY	NOTE 5. STOCKHOLDERS’ EQUITY Public Offerings In September 2017, the Company closed an underwritten public offering of 8,846,154 shares of the Company’s common stock at a public offering price of $6.50 per share, before underwriting discounts, which included 1,153,846 shares issued upon the exercise in full by the underwriter of its option to purchase additional shares at the public offering price less the underwriting discounts. The gross proceeds from the offering, before deducting the underwriting discounts and commissions and other offering expenses payable by the Company, were $57.5 million, with net proceeds to the Company of $53.7 million. In January 2018, the Company closed an underwritten public offering of 15,000,000 shares of the Company’s common stock at a public offering price of $11.50 per share, before underwriting discounts, which included 1,956,521 shares issued upon the exercise in full by the underwriter of its option to purchase additional shares at the public offering price less the underwriting discount. The gross proceeds from the offering, before deducting the underwriting discounts and commissions and other offering expenses payable by the Company, were $172.5 million, with net proceeds to the Company of $162.0 million. On October 17, 2018, the Company completed an underwritten public offering of 25,300,000 shares of the Company’s common stock at a public offering price of $9.97 per share, before underwriting discounts, which included 3,300,000 shares issued upon the exercise in full by the underwriter of its option to purchase additional shares at the public offering price less the underwriting discount. The gross proceeds from the offering, before deducting the underwriting discounts and commissions and other estimated offering expenses payable by the Company, were $252.2 million, with net proceeds to the Company of $236.7 million. Preferred Stock The Company’s certificate of incorporation authorizes the issuance of up to 50,000,000 shares of “blank check” preferred stock. At December 31, 2018, 17,000 shares were designated as Series A Convertible Preferred Stock and 11,500,000 shares were designated as Series B Convertible Preferred Stock (“Series B Convertible Preferred Stock”). Series A Convertible Preferred Stock A total of 17,000 shares of Series A Convertible Preferred Stock have been authorized for issuance under the Company’s Certificate of Designation of Preferences and Rights of Series A Convertible Preferred Stock. The shares of Series A Convertible Preferred Stock have a stated value of $1,000 per share and are initially convertible into shares of common stock at a price of $2.00 per share, subject to adjustment. The Series A Convertible Preferred Stock may, at the option of each investor, be converted into fully paid and non-assessable shares of common stock. The holders of shares of Series A Convertible Preferred Stock do not have the right to vote on matters that come before the Company’s stockholders. In the event of any dissolution or winding up of the Company, proceeds shall be paid pari passu among the holders of common stock and preferred stock, pro rata based on the number of shares held by each holder. The Company may not declare, pay or set aside any dividends on shares of capital stock of the Company (other than dividends on shares of common stock payable in shares of common stock) unless the holders of the Series A Convertible Preferred Stock shall first receive an equal dividend on each outstanding share of Series A Convertible Preferred Stock. The common shares issued were determined on a formula basis of 500 common shares for each share of Series A Convertible Preferred Stock converted. During the year ended December 31, 2018, 1,500 shares of Series A Convertible Preferred Stock were converted into 750,000 shares of common stock, respectively. No Shares of Series A Convertible Preferred Stock were converted in fiscal year 2017 or 2016. The common shares issued were determined on a formula basis of 500 common shares for each share of Series A Convertible Preferred Stock converted. At December 31, 2018, 194 shares of Series A Convertible Preferred Stock (that are convertible into 97,000 shares of common stock) remained outstanding. Series B Convertible Preferred Stock A total of 11,500,000 shares of Series B Convertible Preferred Stock are authorized for issuance under the Company’s Series B Certificate of Designation of Rights, Preferences and Privileges of Series B Convertible Preferred Stock. The shares of Series B Convertible Preferred Stock have a stated value of $4.75 per share and are convertible into shares of the Company’s common stock at an initial conversion price of $4.75 per share. Holders of Series B Convertible Preferred Stock are entitled to dividends on an as-if-converted basis in the same form as any dividends actually paid on shares of the Series A Convertible Preferred Stock or the Company’s common stock. So long as any Series B Convertible Preferred Stock remains outstanding, the Company may not redeem, purchase or otherwise acquire any material amount of the Series A Convertible Preferred Stock or any securities junior to the Series B Convertible Preferred Stock. During the year ended December 31, 2018, 2017 and 2016, 1,523,396, 568,432, and 3,421,960 shares of Series B Convertible Preferred Stock were converted into 1,523,396, 568,432, and 3,421,960 shares of common stock, respectively. At December 31, 2018, 5,854,845 shares of Series B Preferred Stock (that are convertible into 5,854,845 shares of common stock) remained outstanding. 2016 Private Placement On June 2, 2016, the Company entered into a securities purchase agreement with various institutional and individual accredited investors to raise gross proceeds of $100 million in a private placement (the “2016 Private Placement”). On June 7, 2016, the Company completed the 2016 Private Placement. In the 2016 Private Placement, the Company issued (i) 9,684,000 shares of its common stock and (ii) 11,368,633 shares of its newly created Series B Preferred Stock. The shares of common stock and Series B Preferred Stock were sold for $4.75 per share. The shares of Series B Preferred initially were not convertible into common stock and, except as required by law, are non-voting. On July 7, 2016, the Company filed a proxy statement with the SEC with respect to a stockholders meeting that was held on August 16, 2016 at which the stockholders were asked to vote on a proposal to permit the Series B Preferred Stock to become convertible into shares of the Company’s common stock and to permit the issuance of shares of common stock upon such conversion. The requisite stockholder approval was obtained and, as a result, on August 16, 2016 the Series B Preferred Stock became convertible into shares of common stock at an initial conversion price of $4.75 per share. The Company has also evaluated its convertible preferred stock in accordance with the provisions of ASC 815, Derivatives and Hedging, including consideration of embedded derivatives requiring bifurcation. The issuance of the convertible preferred stock could generate a beneficial conversion feature (“BCF”), which arises when a debt or equity security is issued with an embedded conversion option that is beneficial to the investor or in the money at inception because the conversion option has an effective strike price that is less than the market price of the underlying stock at the commitment date. The Company recognized the BCF by allocating the intrinsic value of the conversion option, which is the number of shares of common stock available upon conversion multiplied by the difference between the effective conversion price per share and the fair value of common stock per share on the commitment date, to additional paid-in capital, resulting in a discount on the convertible preferred stock. As the convertible preferred stock may be converted immediately, the Company recognized a BCF of $49.5 million as a deemed dividend in the statements of operations. This one-time, non-cash charge impacted net loss attributable to common stockholders and loss per share for the year ended December 31, 2016. The Company received net proceeds of approximately $95.7 million from the 2016 Private Placement, after paying placement agent fees and estimated offering expenses. Warrants There were no remaining outstanding warrants as of December 31, 2018. A summary of the status of stock warrants at December 31, 2018 and the changes during the three years then ended, is presented in the following table. Weighted Weighted Aggregate Shares Average Average Intrinsic Under Exercise Remaining Value Warrants Price Life (in thousands) Outstanding at January 1, 2016 7,202,216 $ 2.51 Issued - - Exercised (592,132 ) 2.50 Expired/Cancelled (43,868 ) 2.51 Outstanding at December 31, 2016 6,566,216 $ 2.51 Issued - - Exercised (265,000 ) 2.50 Expired/Cancelled - - Outstanding at December 31, 2017 6,301,216 $ 2.51 Issued - - Exercised (6,301,216 ) 2.51 Expired/Cancelled - - Outstanding at December 31, 2018 - $ - - $ -

STOCK BASED COMPENSATION

STOCK BASED COMPENSATION	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK BASED COMPENSATION	NOTE 6. STOCK BASED COMPENSATION Stock Plans As of October 14, 2011, the Company adopted the 2011 Equity Incentive Plan (the “2011 Plan”). Employees, directors, consultants and advisors of the Company are eligible to participate in the 2011 Plan. The 2011 Plan initially had 180,000 shares of common stock reserved for issuance in the form of incentive stock options, non-qualified options, common stock, and grant appreciation rights. The 2011 Plan was not approved by the Company’s stockholders within the required one-year period following its adoption and, accordingly, no incentive stock options can be granted under that plan. In August 2013, the Company’s Board of Directors and a majority of the Company’s stockholders approved an amendment to increase the number of shares available under the 2011 Plan from 180,000 shares to 1,700,000 shares, and an amendment to increase the number options or other awards that can be granted to any one person during a twelve (12) month period from 50,000 shares to 300,000 shares. The foregoing amendment to the 2011 Plan became effective in September 2013. On August 20, 2014, the Company’s Board of Directors amended the 2011 Plan to increase the number of shares available for issuance upon the exercise of stock options under the 2011 Plan from 1,700,000 to 1,900,000 shares, effective immediately. As of December 31, 2018, 376,240 shares were available for future grant under the 2011 Plan. On September 19, 2014, the Company’s Board of Directors (the “Board”) adopted the Iovance Biotherapeutics, Inc. 2014 Equity Incentive Plan (the “2014 Plan”). The 2014 Plan was approved by the Company’s stockholders at the Company’s 2014 Annual Meeting of Stockholders held in November 2014. The 2014 Plan, as approved by the stockholders, authorized the issuance up to an aggregate of 2,350,000 shares of the Company’s common stock. On April 10, 2015, the Board amended the 2014 Plan to increase the total number of shares that can be issued under the 2014 Plan to 4,000,000 shares of the Company’s common stock. The increase in shares available for issuance under the 2014 Plan was approved by the Company’s stockholders at the Company’s 2015 Annual Meeting of Stockholders in June 2015. On August 16, 2016, the Company’s stockholders approved an increase in the total number of shares that can be issued under the 2014 Plan to 9,000,000 shares of the Company’s common stock. At December 31, 2018, 579,809 shares were available for grant under the Company’s 2014 Plan. On April 22, 2018, the Board adopted the Iovance Biotherapeutics, Inc. 2018 Equity Incentive Plan (the “2018 Plan”). The 2018 Plan was approved by the Company’s stockholders at the annual meeting of stockholders held in June 2018. The 2018 Plan as approved by the stockholders authorized the issuance up to an aggregate of 6,000,000 shares of common stock reserved for issuance in the form of incentive (qualified) stock options, non-qualified options, common stock, stock appreciation rights, restricted stock awards, restricted stock units, other stock-based awards, other cash-based awards or any combination of the foregoing. At December 31, 2018, 6,000,000 shares of common stock were available for grant under the Company’s 2018 Plan. The Company anticipates granting the remaining shares under the 2011 and 2014 Plans prior to granting shares from the 2018 Plan. Restricted Stock Units On June 1, 2016, the Company entered into a restricted stock unit agreement with the Company’s new Chief Executive Officer, Maria Fardis, Ph.D., pursuant to which the Company granted Dr. Fardis 550,000 non-transferrable restricted stock units at fair market value of $5.87 per share as an inducement of employment pursuant to the exception to The Nasdaq Global Market rules that generally require stockholder approval of equity incentive plans. The 550,000 restricted stock units vest in installments as follows: (i) 137,500 restricted stock units vested upon the first anniversary of the effective date of Dr. Fardis’ employment agreement; (ii) 275,000 restricted stock units vest upon the satisfaction of certain clinical trial milestones; and (iii) 137,500 restricted stock units vest in equal monthly installments over the 36-month period following the first anniversary of the effective date of Dr. Fardis’ employment, provided that Dr. Fardis has been continuously employed with the Company as of such vesting dates. As of December 31, 2018, 68,749 restricted stock units remained unvested. Stock-based compensation expense for restricted stock units are measured based on the closing fair market value of the Company's common stock on the date of grant. The stock-based compensation expenses relating to restricted stock units were $0.3 million, $1.1 million and $1.5 million for the years ended December 31, 2018, 2017 and 2016, respectively, recorded as part of general and administrative expenses. As of December 31, 2018, $0.4 million of total unrecognized compensation costs related to non-vested restricted stock units to be recognized over a weighted average period of 1.42 years. Stock Options A summary of the status of stock options at December 31, 2018, and the changes during the three years then ended, is presented in the following table: Weighted Weighted Average Aggregate Number Average Remaining Intrinsic of Exercise Contractual Value Options Price Life (in thousands) Outstanding at January 1, 2016 2,693,237 $ 8.12 Issued 4,407,983 6.86 Exercised (100,480 ) 6.23 Expired/Cancelled (767,590 ) 8.12 Outstanding at December 31, 2016 6,233,150 $ 7.24 Issued 2,188,800 6.68 Exercised (1,011,284 ) 5.55 Expired/Cancelled (1,338,298 ) 6.79 Outstanding at December 31, 2017 6,072,368 $ 7.42 Issued 2,960,620 14.73 Exercised (1,336,514 ) 7.45 Expired/Cancelled (807,187 ) 10.04 Outstanding at December 31, 2018 6,889,287 $ 10.25 8.30 years $ 7,186 Exercisable at December 31, 2018 3,118,910 $ 7.88 7.56 years $ 4,745 The Company recorded stock-based compensation expenses related to stock options of $19.8 million, $10.9 million and $16.5 million for the years ended December 31, 2018, 2017 and 2016, respectively. As of December 31, 2018, there was $35.0 million of total unrecognized compensation expenses related to non-vested employee options to be recognized over a weighted average period of 1.82 years. The weighted average grant date fair value for employee options granted under the Company's stock option plans during the years ended December 31, 2018, 2017 and 2016 was $14.44, $6.58, and $6.78 per option respectively. The aggregate intrinsic value in the table above reflects the total pre-tax intrinsic value (the difference between the Company’s closing stock price on the last trading day of the year ended December 31, 2018 and the exercise price of the options, multiplied by the number of in-the-money stock options) that would have been received by the option holders had all option holders exercised their options on December 31, 2018. The intrinsic value of the Company’s stock options changes based on the closing price of the Company’s common stock. The total pre-tax intrinsic value of stock options exercised during the year ended December 31, 2018, 2017 and 2016 were $2.3 million, $2.6 million, and $0.2 million, respectively. The following table summarizes the assumptions relating to options granted pursuant to the Company’s equity incentive plans for the years ended December 31, 2018, 2017, and 2016: Years Ended December 31, 2018 2017 2016 Expected dividend yield 0% 0% 0% Risk-free interest rate 2.97% - 2.27% 2.34% - 1.72% 2.16% - 1.18% Expected term (in years) 6.50 - 5.13 6.50 - 5.13 6.50 - 5.07 Expected volatility 200.28% - 167.54% 209.69% - 190.46% 213.60% - 189.40% Expected Dividend Yield —The Company has never paid dividends and does not expect to pay dividends in the foreseeable future. Risk-Free Interest Rate —The risk-free interest rate was based on the market yield currently available on United States Treasury securities with maturities approximately equal to the option’s expected term. Expected Term —The expected term of the stock option grants was calculated based on historical exercises, cancellations, and forfeitures of stock options and outstanding option shares Expected Volatility —The expected volatility is based on the historical volatility for the Company's stock over a period equal to the expected terms of the options. Forfeiture Rate —The Company recognizes forfeitures as they occur. Each of the inputs discussed above is subjective and generally requires significant management judgment. A summary of outstanding and exercisable stock options as of December 31, 2018 is as follows: Options Outstanding Options Exercisable Range of Exercise Prices Number of Shares Weighted Average Remaining Contractual Life Weighted Average Exercise Price Per Share Number of Shares Weighted Average Remaining Contractual Life Weighted Average Exercise Price Per Share $5.05 - $5.87 1,123,800 7.79 $ 5.55 743,376 7.69 $ 5.56 $5.87 - $7.45 758,109 7.67 6.92 473,398 7.18 6.94 $7.46 - $7.55 897,625 7.87 7.55 662,832 7.87 7.55 $7.56 - $8.17 804,283 7.75 7.86 522,596 7.26 7.84 $8.18 - $9.15 712,500 7.69 8.99 502,708 7.66 9.10 $9.16 - $13.85 732,850 9.17 11.66 123,750 6.45 11.05 $13.86 - $16.25 690,700 9.43 15.13 81,250 9.38 15.26 $16.26 - $16.80 961,420 9.10 16.66 - - - $16.81 - $115.00 206,000 8.96 21.24 7,000 2.84 94.01 $115.01 117.00 2,000 2.32 117.00 2,000 2.32 117.00 6,889,287 8.30 $ 10.25 3,118,910 7.56 $ 7.88 Restricted Common Stock Awards The following table summarizes restricted common stock awards activity: Weighted Average Grant Date Number of Share Fair Value Non-vested shares, January 1, 2016 321,252 $ 6.96 Granted - - Vested (274,167 ) 6.90 Forfeited (40,001 ) 7.02 Non-vested shares, December 31, 2016 7,084 $ 6.48 Granted - - Vested (7,084 ) 6.48 Forfeited - - Non-vested shares, December 31, 2017 - - Granted - $ - Vested - - Forfeited - - Non-vested shares, December 31, 2018 - $ - There were no unvested restricted common stock awards as of December 31, 2018 and 2017. During the year ended December 31, 2018 and 2017, no expense was recognized in connection with these awards. During the year ended December 31, 2016, the Company recorded compensation expenses of $1.0 million in connection with these awards.

EMPLOYEE BENEFIT PLAN

EMPLOYEE BENEFIT PLAN	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Compensation and Employee Benefit Plans	NOTE.7 EMPLOYEE BENEFIT PLAN The Company maintains a defined contribution plan covering substantially all U.S. employees under Section 401(k) of the Internal Revenue Code of 1986, as amended (the “IRC”). The Company's matching contribution to the plan were $0.5 million, $0.3 million, and $0.1 million for the years ended December 31, 2018, 2017 and 2016, respectively.

SEPARATION AGREEMENTS

SEPARATION AGREEMENTS	12 Months Ended
	Dec. 31, 2018
Restructuring and Related Activities [Abstract]
Separation Agreements Disclosure	NOTE 8. SEPARATION AGREEMENTS In June 2016, the Company entered into a separation agreement with Dr. Elma Hawkins, its former Chief Executive Officer. Under the terms of the agreement, Dr. Hawkins vesting was accelerated on certain outstanding options and she was entitled to receive a severance payment of approximately $0.5 million. The Company recorded approximately $5.0 million in additional share-based compensation expense related to this acceleration of the equity awards during the year ended December 31, 2016. In July 2016, Molly Henderson, the former Chief Financial Officer provided the Board with written notice under her Employment Agreement, dated June 5, 2015, that she would terminate her employment with the Company for “good reason” effective August 16, 2016. In connection with this event all unvested options were accelerated, and she received a severance payment of approximately $0.4 million, representing one year’s salary. The Company recorded approximately $4.5 million in additional share-based compensation expense related to the acceleration of the equity awards during the year ended December 31, 2016.

INCOME TAXES

INCOME TAXES	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	NOTE 9. INCOME TAXES Net deferred tax assets (liabilities) are summarized as follows (in thousands): As of December 31, 2018 2017 Deferred income tax asset: Net operating loss carry forward $ 56,971 $ 33,300 Stock-based compensation 5,823 4,568 Tax credit carry forwards 14,356 9,323 Reserves and accruals 1,049 733 Deferred tax assets before valuation allowance 78,199 47,924 Less: valuation allowance (78,146 ) (47,849 ) Net deferred income tax assets 53 75 Deferred tax liabilities: Depreciation and amortization (53 ) (75 ) Net deferred tax assets (liabilities) $ - $ - Reconciliation of the effective income tax rate to the U.S. statutory rate is as follows: Years ended December 31, 2018 2017 2016 Federal statutory tax rate (21 )% (34 )% (34 )% Orphan Drug & Research credits (3 ) 0 (8 ) Permanent and other differences 1 4 4 Tax rate change - 23 - State tax, net of federal benefit (1 ) - (4 ) (24 )% (7 )% (42 )% Valuation allowance 24 % 7 % 42 % Effective tax rate - % - % - % The components of income tax expense (benefit) are as follows (in thousands): Years Ended December 31, 2018 2017 2016 Federal: Current $ - $ - $ - Deferred (28,277 ) (7,391 ) (19,050 ) State and Local Current - - - Deferred (2,020 ) 944 (3,007 ) Change in Valuation Allowance 30,297 6,447 22,057 Total income tax expense (benefit) $ - $ - $ - The Company had net operating loss carryovers (“NOLs”) for federal and state income tax purposes of approximately $251.5 million and $88.9 million, respectively, as of December 31, 2018. $142.4 million of federal NOLs will expire beginning in 2027, while $109 million generated after Tax Reform will have an indefinite life. The state NOLs will expire if unused in years 2031 through 2038. The Company’s utilization of NOLs is subject to an annual limitation due to ownership changes that have occurred previously or that could occur in the future as provided in Section 382 of the IRC (“Section 382”), as well as similar state provisions. Section 382 limits the utilization of NOLs when there is a greater than 50% change of ownership as determined under the regulations. Since its formation, the Company has raised capital through the issuance of capital stock and various convertible instruments which, combined with the purchasing shareholders’ subsequent disposition of these shares, has resulted in an ownership change as defined by Section 382, and could result in an ownership change in the future upon subsequent disposition. On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (“the Act”) was signed into law making significant changes to the Internal Revenue Code. Changes include, but are not limited to, a corporate tax rate decrease from 35% to 21% effective for tax years beginning after December 31, 2017, the transition of U.S international taxation from a worldwide tax system to a territorial system, and a one-time transition tax on the mandatory deemed repatriation of cumulative foreign earnings as of December 31, 2017. In accordance with the Act, the Company recorded a reduction of $20.8 million to the Company’s deferred tax assets, and a corresponding decrease of the same amount in the valuation allowance against these deferred tax assets in the fourth quarter of 2017. The Company concluded the tax accounting consideration associated with the Act and no material adjustments were recorded in 2018. In assessing the realization of deferred tax assets, management considers whether it is more likely than not that some portion or all the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon future generation for taxable income during the periods in which temporary differences representing net future deductible amounts become deductible. Management considers the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in making this assessment. After consideration of all the information available, management believes that significant uncertainty exists with respect to future realization of the deferred tax assets and has therefore established a full valuation allowance. For the years ended December 31, 2018, 2017 and 2016, the change in the valuation allowance was approximately $30.3 million, 6.4 million, and $22.1 million, respectively. The Company evaluated the provisions of ASC 740 related to the accounting for uncertainty in income taxes recognized in an enterprise’s financial statements. ASC 740 prescribes a comprehensive model for how a company should recognize, present, and disclose uncertain positions that the company has taken or expects to take in its tax return. For those benefits to be recognized, a tax position must be more-likely-than-not to be sustained upon examination by taxing authorities. Differences between tax positions taken or expected to be taken in a tax return and the net benefit recognized and measured pursuant to the interpretation are referred to as “unrecognized benefits.” A liability is recognized (or amount of net operating loss carry forward or amount of tax refundable is reduced) for unrecognized tax benefit because it represents an enterprise’s potential future obligation to the taxing authority for a tax position that was not recognized as a result of applying the provisions of ASC 740. If applicable, interest costs related to the unrecognized tax benefits are required to be calculated and would be classified as income tax expenses in the consolidated statement of operations. Penalties would be recognized as a component of “General and Administrative Expenses” in the consolidated statement of operations. A reconciliation of the beginning and ending balances of the unrecognized tax benefits during the years ended December 31, 2018, 2017 and 2016 is as follows (in thousands): Years Ended December 31, 2018 2017 2016 Unrecognized benefit - beginning of period $ 4,111 $ - $ - Gross decreases - prior period tax positions 118 2,780 - Gross increase current period tax positions 2,115 1,331 - Unrecognized benefit - end of period $ 6,344 $ 4,111 $ - No interest or penalties on unpaid tax were recorded during the years ended December 31, 2018, 2017 and 2016, respectively. The Company does not anticipate any significant changes within 12 months of this reporting date of its uncertain tax positions. The Company files tax returns in the U.S. federal and state jurisdictions. The U.S. federal and U.S. state taxing authorities may choose to audit tax returns for tax years beyond the statute of limitation period due to significant tax attribute carryforwards from prior years, making adjustments only to carryforward attributes. The Company is not currently under examination by income tax authorities in federal, state or other foreign jurisdictions.

LICENSES AND AGREEMENTS

LICENSES AND AGREEMENTS	12 Months Ended
	Dec. 31, 2018
Licenses And Agreements [Abstract]
LICENSES AND AGREEMENTS	NOTE 10. LICENSES AND AGREEMENTS National Institutes of Health (NIH) and the National Cancer Institute (NCI) Cooperative Research and Development Agreement (CRADA) In August 2011, the Company signed a five-year CRADA with the NCI to work with Dr. Steven Rosenberg on developing adoptive cell immunotherapies that are designed to destroy metastatic melanoma cells using a patient’s tumor infiltrating lymphocytes. In January 2015, the Company executed an amendment (the “Amendment”) to the CRADA to include four new indications. As amended, in addition to metastatic melanoma, the CRADA included the development of TIL therapy for the treatment of patients with bladder, lung, triple-negative breast, and Human Papilloma Virus (“HPV”)-associated cancers. In August 2016, the NCI and the Company entered a second amendment to the CRADA. The principal changes effected by the second amendment included (i) extending the term of the CRADA by another five years to August 2021, and (ii) modifying the focus on the development of unmodified TIL as a stand-alone therapy or in combination with U.S. Food and Drug Administration (“FDA”) licensed products and commercially available reagents routinely used for adoptive cell therapy. The parties will continue the development of improved methods for the generation and selection of TIL with anti-tumor reactivity in metastatic melanoma, bladder, lung, breast, and HPV-associated cancers. Pursuant to the terms of the CRADA, as amended, the Company is required to make quarterly payments of $0.5 million to the NCI for support of research activities. To the extent the Company licenses patent rights relating to a TIL-based product candidate under this agreement, the Company will be responsible for all patent-related expenses and fees, past and future, relating to the TIL-based product candidate. In addition, the Company may be required to supply certain test articles, including TIL, grown and processed under cGMP conditions, suitable for use in clinical trials, where the Company holds the investigational new drug application for such clinical trial. The extended CRADA has a five-year term expiring in August 2021. The Company or the NCI may unilaterally terminate the CRADA for any reason or for no reason at any time by providing written notice at least 60 days before the desired termination date. The Company recorded costs associated with the CRADA of $2.0 million, $2.0 million, and $1.8 million for the years ended December 31, 2018, 2017 and 2016, respectively, as research and development expenses. Patent License Agreement Related to the Development and Manufacture of TIL Effective October 5, 2011, the Company entered into an Exclusive Patent License Agreement (the “Exclusive Patent License Agreement”) with the NIH, an agency of the United States Public Health Service within the Department of Health and Human Services (NIH), which was subsequently amended on February 9, 2015 and October 2, 2015. Pursuant to the Patent License Agreement, as amended, the NIH granted the Company licenses, including exclusive, co-exclusive, and non-exclusive licenses, to certain technologies relating to autologous tumor infiltrating lymphocyte adoptive cell therapy products for the treatment of metastatic melanoma, lung, breast, bladder and HPV-positive cancers. Unless terminated sooner, the license shall remain in effect until the last licensed patent right expires. The Patent License Agreement requires the Company to pay royalties based on a percentage of net sales (which percentage is in the mid-single digits), a percentage of revenues from sublicensing arrangements, and lump sum benchmark royalty payments on the achievement of certain clinical and regulatory milestones for each of the various indications and other direct costs incurred by the NIH pursuant to the agreement. Exclusive Patent License Agreement Related to TIL Selection On February 10, 2015, the Company entered into an Exclusive Patent License Agreement (the “Exclusive Patent License Agreement”) with the NIH under which the Company received an exclusive license to the NIH’s rights to patent-pending technologies related to methods for improving adoptive cell therapy through more potent and efficient production of TIL from melanoma tumors by selecting for T-cell populations that express various inhibitory receptors. Unless terminated sooner, the license shall remain in effect until the last licensed patent right expires. Under the Exclusive Patent License Agreement, the Company agreed to pay customary royalties based on a percentage of net sales of a licensed product (which percentage is in the mid-single digits), a percentage of revenues from sublicensing arrangements, and lump sum benchmark payments upon the successful completion of clinical studies involving licensed technologies, the receipt of the first FDA approval or foreign equivalent for a licensed product or process resulting from the licensed technologies, the first commercial sale of a licensed product or process in the United States, and the first commercial sale of a licensed product or process in any foreign country. H. Lee Moffitt Cancer Center Research Collaboration and Clinical Grant Agreements with Moffitt In December 2016, the Company entered into a new three-year Sponsored Research Agreement with H. Lee Moffitt Cancer Center (“Moffitt”). At the same time, the Company entered into a clinical grant agreement with Moffitt to support an ongoing clinical trial at Moffitt that combines TIL therapy with nivolumab for the treatment of patients with metastatic melanoma. In June 2017, the Company entered into a second clinical grant agreement with Moffitt to support a new clinical trial at Moffitt that combines TIL therapy with nivolumab for the treatment of patients with non-small cell lung cancer, under which the Company obtained a non-exclusive, royalty-free license to any new Moffitt inventions made in the performance of the agreement. Under both clinical grant agreements with Moffit, the Company has non-exclusive rights to clinical data arising from the respective clinical trials. In the years ended December 31, 2018, 2017 and 2016, the Company recorded research and development costs of $1.2 million, $1.2 million, and $0.7 million, respectively, in connection with the research collaboration and clinical grant agreements with Moffitt. Exclusive License Agreements with Moffitt The Company entered into a license agreement with Moffitt (the “First Moffitt License”), effective as of June 28, 2014, under which the Company received a world-wide license to Moffitt’s rights to patent-pending technologies related to methods for improving TIL for adoptive cell therapy using toll-like receptor agonists. Unless earlier terminated, the term of the license extends until the earlier of the expiration of the last issued patent related to the licensed technology or 20 years after the effective date of the license agreement. Pursuant to the First Moffitt License, the Company paid an upfront licensing fee in the amount of $0.1 million. A patent issuance fee will also be payable under the First Moffitt License, upon the issuance of the first U.S. patent covering the subject technology. In addition, the Company agreed to pay milestone license fees upon completion of specified milestones, customary royalties based on a specified percentage of net sales (which percentage is in the low single digits) and sublicensing payments, as applicable, and annual minimum royalties beginning with the first sale of products based on the licensed technologies, which minimum royalties will be credited against the percentage royalty payments otherwise payable in that year. The Company will also be responsible for all costs associated with the preparation, filing, maintenance and prosecution of the patent applications and patents covered by the First Moffitt License related to the treatment of any cancers in the United States, Europe and Japan and in other countries designated by the Company in agreement with Moffitt. The Company entered into a license agreement with Moffitt effective as of May 7, 2018 (the “Second Moffitt License”), under which the Company received a license to Moffitt’s rights to patent-pending technologies related to the use of 4-1BB agonists in conjunction with TIL manufacturing processes and therapies. Pursuant to the Second Moffitt License, the Company paid an upfront licensing fee in the amount of $0.1 million for the year ended December 31, 2018. An annual license maintenance fee will be also payable commencing on the first anniversary of the effective date. In addition, the Company agreed to pay an annual commercial use payment for each indication for which a first sale has occurred, which in the aggregate amounts to up to $0.4 million a year. PolyBioCept and Karolinska University Hospital PolyBioCept Exclusive and Co-Exclusive License Agreement On September 14, 2016, the Company entered into an exclusive and co-exclusive license agreement (the “PolyBioCept Agreement”) with PolyBioCept AB, a corporation organized under the laws of Sweden (“PolyBioCept”). PolyBioCept has filed two patent applications with claims related to a cytokine cocktail for use in expansion of lymphocytes, one of which has been abandoned. Under the PolyBioCept Agreement, the Company received the exclusive right and license to PolyBioCept’s intellectual property to develop, manufacture, market and genetically engineer TIL produced by expansion, selection and enrichment using a proprietary cytokine cocktail. The Company also received a co-exclusive license (with PolyBioCept) to develop, manufacture and market genetically engineered TIL under the same intellectual property. The licenses are for the use in all cancers and are worldwide in scope, with the exception that the uses in melanoma are not included for certain countries of the former Soviet Union. The Company paid PolyBioCept a total of $2.5 million as an up-front exclusive license payment. The Company will also have to make additional milestone payments to PolyBioCept under the PolyBioCept Agreement if, and when, (i) certain product development milestones are achieved, (ii) certain regulatory approvals have been obtained from the FDA and/or the European Medicines Agency, and (iii) certain product sales targets are achieved. The milestone payments will be payable both in cash (U.S. dollars) and in shares of the Company’s common stock. If all of the foregoing product development, regulatory approval and sales milestone payments are met, the Company will have to pay PolyBioCept an additional $8.7 million and will have to issue to PolyBioCept a total 2,219,376 shares of unregistered common stock. In addition to these potential payments, the Company reimbursed PolyBioCept up to $0.2 million in expenses related to the transfer of know-how and paid PolyBioCept $0.1 million as a clinical trials management fee. The PolyBioCept Agreement has an initial term of 30 years and may be extended for additional five-year periods. No expense in connection with this agreement was recorded for the year ended December 31, 2018. The Company recognized $0.2 and $2.7 million in connection with this agreement for the years ended December 31, 2017 and 2016, respectively, as research and development expense. Karolinska University Hospital and Karolinska Institute Agreements In connection with the execution of the PolyBioCept Agreement, the Company also (i) entered into a clinical trials agreement with the Karolinska University Hospital to conduct clinical trials in glioblastoma and pancreatic cancer at the Karolinska University Hospital, and (ii) agreed to enter into a sponsored research agreement with the Karolinska Institute for the research of the cytokine cocktail in additional indications. In the years ended December 31, 2016, the Company paid Karolinska University Hospital $1.6 million under the clinical trials agreement to conduct the clinical trials. As of April 9, 2018, the Company terminated the clinical trials agreement with the Karolinska University Hospital. In June 2018, the Company received a refund of $1.6 million from Karolinska, which was recorded to offset to research and development expenses for the year ended December 31, 2018. The Company recorded a credit of $0.4 million to research and development expenses in the year ended December 31, 2018, and $0.3 million and $0.1 million as research and development expenses in connection with this agreement in the years ended December 31, 2017 and 2016, respectively. M.D. Anderson Cancer Center Strategic Alliance Agreement In April 2017, the Company entered into a Strategic Alliance Agreement (the “SAA”) with M.D. Anderson Cancer Center (“MDACC”) under which the Company and MDACC agreed to conduct clinical and preclinical research studies. The Company agreed in the SAA to provide total funding not to exceed approximately $14.2 million for the performance of the multi-year studies under the SAA. In return, the Company will acquire all rights to inventions resulting from the studies and has been granted a non-exclusive, sub-licensable, royalty-free, and perpetual license to specified background intellectual property of MDACC reasonably necessary to exploit, including the commercialization thereof. The Company has also been granted certain rights in clinical data generated by MDACC outside of the clinical trials to be performed under the SAA. The SAA’s term shall continue in effect until the later of the fourth anniversary of the SAA or the completion or termination of the research and receipt by the Company of all deliverables due from MDACC thereunder. In May 2017, the Company made a prepayment of $1.4 million under this agreement. The Company recorded $0.8 million associated with the MDACC SAA for the year ended December 31, 2018 as research and development expenses. No expense was recognized in 2017. MedImmune In December 2015, the Company entered into a collaboration agreement (the “MedImmune Agreement”) with MedImmune, the global biologics research and development arm of AstraZeneca (“MedImmune”), to conduct clinical and preclinical research immuno-oncology. Under the MedImmune Agreement, the Company will fund and conduct at least one clinical trial combining MedImmune's PD-L1 inhibitor, durvalumab, which will be supplied by MedImmune, with TIL for the treatment of patients. MedImmune will supply durvalumab for the clinical trials. The purpose of the studies is to establish a dosing regimen for this combination therapy and assess its safety and efficacy. WuXi In November 2016, the Company entered into a three-year manufacturing and services agreement (“MSA”) with WuXi AppTech, Inc. (“Wuxi”) pursuant to which WuXi agreed to provide manufacturing and other services. Under the agreement, the Company entered into two statements of work for two cGMP manufacturing suites to be established and operated by WuXi for the Company, one of the suites is expected to be capable of being used for the commercial manufacture of our products. The statements of work for each facility include a fixed component to reserve a dedicated suite and a variable component, mainly labor and materials used during the manufacturing process. The fee payable under the first statement of work for the use of one of the manufacturing suites during the first year of the agreement, including the fees for the necessary personnel, was $2.5 million. The second statement of work, under which WuXi agreed to establish and operate a second, dedicated facility for a late stage/commercial manufacturing cGMP suite requires the Company to pay approximately $5.85 million during the first year of the agreement. The Company and WuXi have extended the term of the related statements of work until May 2020. The Company and WuXi have extended the term of the related statements of work until May 2020. The Company recorded costs associated with agreements with WuXi of $15.1 million, $13.9 million, and $1.3 million for the years ended December 31, 2018, 2017, and 2016 respectively, as research and development expenses.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	NOTE 11. COMMITMENTS AND CONTINGENCIES Facilities Leases Tampa Lease In December 2014, the Company commenced a five-year non-cancellable operating lease with the University of South Florida Research Foundation for a 5,115 square foot facility located in Tampa, Florida. The facility is part of the University of South Florida research park and is used as the Company’s research and development facilities. The Company has the option to extend the lease term of this facility for an additional five-year period on the same terms and conditions, except that the base rent for the renewal term will be increased in accordance with the applicable consumer price index. In April 2015, the Company amended the original lease agreement to increase the rentable space to 6,043 square feet. In September 2016, the Company further increased the rentable space to 8,673 square feet. The per square foot cost and term of the lease were unchanged, and rent payments are approximately $20,000 per month. The lease expires in December 2019. San Carlos Lease On August 4, 2016, the Company entered into an agreement to lease 8,733 square feet in San Carlos, California. The term of the lease is 54 months subsequent to the commencement date and will expire in April 2021. Monthly lease payments are approximately $38,000. On April 28, 2017, the Company entered into a sublease agreement with Teradata US, Inc., pursuant to which the Company agreed to sublease certain office space located adjacent to the Company's headquarters for approximately $26,000 per month. The space consists of approximately 11,449 rentable square feet in the building located in San Carlos, California. The sublease for this space expired on October 31, 2018. Monthly lease payments were approximately $26,000. On October 19, 2018, the Company entered into an agreement to lease 12,322 square feet of office space located adjacent to the Company's headquarters in San Carlos, California. This lease replaces the sublease of 11,449 square feet of office space in the same facility that expired on October 31, 2018. The term of the lease is 30 months subsequent to the commencement date, November 1, 2018, and will expire in April 2021. Monthly lease payments are approximately $59,000, subject to an annual increase of 3%. New York Lease The Company leased office space in New York for a monthly rental of approximately $18,000 a month from January 2017 through July 2017. On June 5, 2017, the Company entered into an agreement whereby the Company will lease office space from August 1, 2017 to July 31, 2018, for approximately $9,000 a month. On April 20, 2018, the Company entered into an agreement to extend the lease term to January 31, 2019 for approximately $7,000 a month. On November 2, 2018, the Company entered into an agreement to extend the lease term to July 31, 2019 for approximately $4,000 a month. The Company recognizes rental expense on the facilities on a straight-line basis over the lease term. Differences between the straight-line rent expense and rent payments are classified as deferred rent liability on the balance sheet. Rent expense for the years ended December 31, 2018, 2017 and 2016 was $1.0 million, $1.0 million, and $0.7 million, respectively. Contract Manufacturing Organizations The Company uses contract manufacturing organizations (CMOs) for its clinical production and manufacturing activities. In conjunction with the adoption of Topic 842 on January 1, 2019, the Company reevaluated all of its material contracts it has, to determine whether they contain a lease under the current lease guidance ASC 840. An arrangement is considered a lease or contains a lease if an underlying asset is explicitly or implicitly identified and use of the asset is controlled by the customer. Based on the evaluation, the Company concluded that all of its contracts with CMOs contained embedded operating leases, in addition to other CMO fixed contractual obligations, because the facilities used for its production are implicitly identified, only used by the Company exclusively during the contractual term of the arrangements, and the CMOs have no substantive contractual rights to substitute the facilities used by the Company. Further, the Company controls the use of the facilities by obtaining all of the economic benefits from the use of the facilities and directing the use of the facilities throughout the period of use. Under the current lease guidance, embedded leases are off-balance sheet operating leases and, as such, application of lease accounting did not have any impact on the balance sheet as of December 31, 2018 and 2017. However, they are reflected in the commitments tables below. As of December 31, 2018, the Company's future minimum lease payments under non-cancelable operating leases are as follows (in thousands): Payments due by period Contractual Obligations Total 2019 2020 2021 2022 Thereafter Facility leases $ 3,014 $ 1,373 $ 1,223 $ 418 $ - $ - CMO contractual obligations 28,587 17,992 7,690 2,324 581 - Total $ 31,601 $ 19,365 $ 8,913 $ 2,742 $ 581 $ - Operating lease obligations consist of obligations under non-cancelable operating leases for our facilities in San Carlos, CA, Tampa, FL, and New York, NY. CMO contractual obligations consist of embedded lease obligations for the manufacturing facilities and minimum fixed commitment fees included in the Company’s manufacturing contracts, such as personnel, general support fee, and minimum production or material fees.

LEGAL PROCEEDINGS

LEGAL PROCEEDINGS	12 Months Ended
	Dec. 31, 2018
Loss Contingency [Abstract]
LEGAL PROCEEDINGS	NOTE 12. LEGAL PROCEEDINGS Class Action Lawsuit In the Matter of Certain Stock Promotion Leonard DeSilvio v. Lion Biotechnologies, Inc., et al., (Amra Kuc vs. Lion Biotechnologies, Inc., et al., In the Matter of Certain Stock Promotions Kuc Kuc Jay Rabkin v. Lion Biotechnologies, Inc., et al., In the Matter of Certain Stock Promotions Derivative Lawsuits. In the Matter of Certain Stock Promotions On March 28, 2018, a purported stockholder derivative complaint was filed by plaintiff Nazeer Khaleeluddin on behalf of the Company, against the Company, as nominal defendant, and certain of the Company’s current and former officers and directors, and others, as defendants, in the U.S. District Court for the District of Delaware (case no. 1:18-cv-00469). The complaint alleges, among other things, violations of securities law, breach of fiduciary duty, aiding and abetting, waste of corporate assets, and unjust enrichment. The complaint is based on claims arising from the SEC’s investigation in the In the Matter of Certain Stock Promotions The Company intends to vigorously defend against the foregoing complaints. Based on the early stage of the litigation, it is not possible to estimate the amount or range of possible loss that might result from an adverse judgment or a settlement of these matters. Solomon Capital, LLC. Solomon Capital, LLC, Solomon Capital 401(K) Trust, Solomon Sharbat and Shelhav Raff v. Lion Biotechnologies, Inc. On June 3, 2016, the Company filed an answer and counterclaims in the lawsuit. In its counterclaims, the Company alleges that the plaintiffs misrepresented their qualifications to assist the Company in fundraising and that they failed to disclose that they were under investigation for securities laws violations. The Company is seeking damages in an amount exceeding $0.5 million and an order rescinding any and all agreements that the plaintiffs contend entitled them to obtain stock in the Company. On April 19, 2017, the court granted plaintiffs’ counsel’s motion to withdraw from the case. On May 25, 2017, plaintiffs filed a notice that they had hired new counsel. On June 7, 2017, the judge presiding over the case recused herself because of a conflict of interest arising from her relationship with plaintiffs’ new attorneys and the case was subsequently assigned to a new judge. On April 20, 2018, the court held a hearing regarding plaintiff’s motion to dismiss the Company’s amended counterclaims and affirmative defense for fraudulent inducement. On August 15, 2018, the court entered an order granting the plaintiffs’ motion and dismissed the Company’s amended counterclaims and eleventh affirmative defense for fraudulent inducement without leave to amend. On September 14, 2018, the Company filed a notice of appeal related to this order, and on November 5, 2018, the Company filed its memorandum of law in support of its appeal of the order dismissing the Company’s amended counterclaims and affirmative defense for fraudulent inducement. On January 2, 2019, plaintiffs filed their memorandum of law in opposition to the appeal. On January 18, 2019, the Company filed its reply brief in support of its appeal of the order dismissing its amended counterclaims and affirmative defense for fraudulent inducement. The Company intends to vigorously defend the complaint and pursue its counterclaims. Litigation Involving Dr. Steven Fischkoff . On June 13, 2017, in an action titled Steven Fischkoff v. Lion Biotechnologies, Inc. and Maria Fardis , Dr. Steven Fischkoff, our former Vice President and Chief Medical Officer, filed a lawsuit against the Company in the Supreme Court of the State of New York, County of New York. Dr. Fischkoff was dismissed by the Company on March 28, 2017. Dr. Fischkoff was terminated “for cause” as that term is defined in his employment agreement. In his complaint, Dr. Fischkoff alleges breaches of his employment agreement and violation of New York Labor Law for failure to pay monies purportedly owed to him, and seeks to recover amounts including severance pay and retention bonus (totaling $300,000), a prorated incentive bonus, and amounts relating to unvested options to 150,000 shares of our common stock, together with prejudgment interest, costs, expenses and attorneys’ fees. On July 5, 2017, we filed a removal petition and removed the lawsuit to the United States District Court for the Southern District of New York, where the case has been assigned case no. 1:17-cv-05041. On July 14, 2017, the Company filed a partial answer and counterclaims against Dr. Fischkoff, denying his allegations, and alleging breach of contract and related claims, breach of fiduciary duty, and state and federal trade secret misappropriation and related claims, and sought a temporary restraining order and preliminary injunction against Dr. Fischkoff. On July 18, 2017, the court issued a temporary restraining order against Dr. Fischkoff requiring him to return our materials, prohibiting him from disclosing or using the Company’s materials, and granting expedited discovery. On June 25, 2018, pursuant to a stipulation between the parties, the court entered a permanent injunction prohibiting Dr. Fischkoff from disclosing, possessing, or using any of the Company’s proprietary materials or trade secrets. On July 5, 2018, the court entered an order dismissing two of Dr. Fischkoff’s claims against the Company and Dr. Fardis. On October 18, 2018, Dr. Fischkoff amended his complaint to assert a new claim for defamation arising from SEC filings in which the Company provided the information about this litigation. The Company intends to vigorously defend against Dr. Fischkoff’s lawsuit and pursue the Company’s counterclaims. Based on the early stage of the litigation, it is not possible to estimate the amount or range of (i) a possible loss that might result from an adverse judgment or settlement of this action, or (ii) the potential recovery that might result from a favorable judgment or a settlement of this action. Other Matters. shares were exercised. The shares of common stock had previously been registered for re-sale. However, the Company believes that these warrant shares were sold by the holders in open market transactions in at a time when the registration statement was ineffective. Accordingly, those sales were not made in accordance with Sections and (a) of the Securities Act of , as amended, and the purchasers of those shares may have rescission rights (if they still own the shares) or claims for damages (if they no longer own the shares). The amount of any such liability is uncertain and as such, an accrual for any potential loss has not been made. The Company believes that any claims brought against it would not result in a material impact to the Company’s financial position or results of operations. The Company has not accrued a loss for a potential claim associated with this matter as it is unable to estimate any at this time. In connection with the Company’s reincorporation from Nevada to Delaware in 2017, the Company (as a Delaware corporation) untimely filed a post-effective amendment to adopt a Form S-8 registration statement that the Company filed (as a Nevada corporation) to register the shares underlying the Company’s 2011 Equity Incentive Plan. Before the Company filed the required post-effective amendment, options to purchase 200,000 shares were exercised under the 2011 Equity Incentive Plan. The effect of the delayed post-effective amendment filing on the 200,000 option shares is uncertain, but the issuance and sale of the shares may not have been in compliance with the Form S-8 registration statement. The existence of any liability to the Company, and the amount of any such liability to the Company, as a result of the issuance of the 200,000 shares is uncertain. Accordingly, no accrual for a potential claim has been made by the Company in its financial statements. The Company may be involved, from time to time, in legal proceedings and claims arising in the ordinary course of our business. Such matters are subject to many uncertainties and outcomes are not predictable with assurance. The Company accrues amounts, to the extent they can be reasonably estimated, that it believes are adequate to address any liabilities related to legal proceedings and other loss contingencies that it believes will result in a probable loss. While there can be no assurances as to the ultimate outcome of any legal proceeding or other loss contingency involving the Company, management does not believe any pending matter will be resolved in a manner that would have a material adverse effect on our financial position, results of operations or cash flows.

QUARTERLY UNAUDITED RESULTS

QUARTERLY UNAUDITED RESULTS	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
QUARTERLY UNAUDITED RESULTS	NOTE 13. QUARTERLY UNAUDITED RESULTS The results of operations by quarter for the years ended December 31, 2018 and 2017 are as follow: 2018 2017 (in thousands, except per share information) Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Revenue $ - $ - $ - $ - - $ - $ - $ - Net loss attributable to common stockholder $ (26,515 ) $ (30,660 ) $ (33,830 ) $ (32,575 ) (20,684 ) $ (23,377 ) $ (22,149 ) $ (25,854 ) Net loss per share, basic and diluted $ (0.31 ) $ (0.34 ) $ (0.36 ) $ (0.27 ) (0.33 ) $ (0.37 ) $ (0.35 ) $ (0.36 ) Weighted average share used in computing net loss per share, basic and diluted 84,350 90,236 95,077 119,085 62,286 62,457 63,332 72,794

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
RELATED PARTY TRANSACTIONS	NOTE 14. RELATED PARTY TRANSACTIONS A former member of the Company’s board of directors was an attorney at a law firm, TroyGould PC, that rendered legal services to the Company during the period of his directorship until June 6, 2018, but did not provide legal services to the Company himself during that period. The Company paid TroyGould PC $0.5 million, $0.7 million, and $0.8 million, during the years ended December 31, 2018, 2017 and 2016, respectively. On September 14, 2017, the Company entered into a three-year consulting agreement with Iain Dukes, D. Phil, the Chairman of the Board. As compensation for his consulting services, the Company granted Dr. Dukes a stock option to purchase up to 150,000 shares of the Company’s common stock, at an exercise price of $7.30 per share. Under the consulting agreement, Dr. Dukes agreed to provide the Company with services regarding business development opportunities, licensing transactions and technology acquisitions by the Company, and any such strategic initiatives appropriate for the Company that Dr. Dukes may identify. The granted stock options vest in 12 quarterly installments (with 1/12th of the option shares having vested on the date of grant). The vesting of the granted stock options will accelerate, and the entire award will become fully vested upon the closing of a significant licensing transaction, a material product acquisition, a material strategic transaction, or upon a change of control transaction. The Company recognized $0.7 million and $0.2 million in stock-based compensation expense related to this consulting agreement during the years ended December 31, 2018 and 2017, respectively.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Cash and Cash Equivalents	Cash, Cash Equivalents, and Short-term Investments The Company’s cash and cash equivalents include short-term investments with original maturities of three months or less when purchased. The Company's short-term investments are classified as “available-for-sale”. The Company includes these investments in current assets and carries them at fair value. Unrealized gains and losses on available-for-sale securities are included in accumulated other comprehensive loss. The cost of debt securities is adjusted for the amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in net interest income in the consolidated statements operations. Gains and losses on securities sold are recorded based on the specific identification method and are included in net interest income in the consolidated statement of operations. The Company has not incurred any realized gains or losses from sales of securities to date. The Company’s investment policy limits investments to certain types of instruments such as certificates of deposit, money market instruments, obligations issued by the U.S. government and U.S. government agencies as well as corporate debt securities, and places restrictions on maturities and concentration by type and issuer.
Property and Equipment, net	Property and Equipment, net Property and equipment is stated at cost, net of accumulated depreciation and amortization. The cost of property and equipment is depreciated or amortized on the straight-line method over the following estimated useful lives: Computer equipment 2 years Office furniture and equipment 5 years Lab equipment 5 years Leasehold improvements Lesser of the remaining economic life of the asset or the lease-term Expenditures for maintenance and repairs are charged to operations as incurred while renewals and betterments are capitalized. Gains and losses on disposals are included within operating expenses in the statements of operations. Management assesses the carrying value of property and equipment whenever events or changes in circumstances indicate that the carrying value may not be recoverable. If there is indication of impairment, management prepares an estimate of future undiscounted cash flows expected to result from the use of the asset and its eventual disposition. If these cash flows are less than the carrying amount of the asset, an impairment loss is recognized to write down the asset to its estimated fair value. For the years ended December 31, 2018, 2017 and 2016, the Company did not recognize any impairments for its property and equipment.
Loss per Share	Loss per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of common shares outstanding during the period. Diluted net loss per share is computed by dividing the net loss by the sum of the weighted average number of shares of common stock outstanding and the dilutive common stock equivalent shares outstanding during the period. The Company’s potentially dilutive common stock equivalent shares, which include incremental common shares issuable upon (i) the exercise of outstanding stock options and warrants (ii) vesting of restricted stock units and restricted stock awards, and (iii) conversion of preferred stock, are only included in the calculation of diluted net loss per share when their effect is dilutive. At December 31, 2018, 2017 and 2016, the following outstanding common stock equivalents have been excluded from the calculation of net loss per share because their impact would be anti-dilutive. As of December 31, 2018 2017 2016 Stock options 6,889,287 6,072,368 6,233,150 Warrants - 6,301,216 6,566,216 Series A Convertible Preferred* 97,000 847,000 847,000 Series B Convertible Preferred* 5,854,845 7,378,241 7,946,673 Restricted stock awards - - 7,084 Restricted stock units 68,742 114,582 550,000 12,909,874 20,713,407 22,150,123 *on an as-converted basis The dilutive effect of potentially dilutive securities would be reflected in diluted earnings per common share by application of the treasury stock method. Under the treasury stock method, an increase in the fair market value of the Company's common stock could result in a greater dilutive effect from potentially dilutive securities.
Fair Value Measurements	Fair Value Measurements Under Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 820, Fair Value Measurements and Disclosures, fair value is defined as the price at which an asset could be exchanged, or a liability transferred in a transaction between knowledgeable, willing parties in the principal or most advantageous market for the asset or liability. Where available, fair value is based on observable market prices or parameters or derived from such prices or parameters. Where observable prices or parameters are not available, valuation models are applied. Assets and liabilities recorded at fair value in the Company’s financial statements are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels directly related to the amount of subjectivity associated with the inputs to fair valuation of these assets and liabilities, are as follows: Level 1—Inputs are unadjusted, quoted prices in active markets for identical assets at the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2—Are inputs, other than quoted prices included in Level 1, that are either directly or indirectly observable for the asset or liability through correlation with market data at the reporting date and for the duration of the instrument’s anticipated life. The fair valued assets the Company holds that are generally assessed under Level 2 are corporate bonds and commercial paper. The Company utilizes third party pricing services in developing fair value measurements where fair value is based on valuation methodologies such as models using observable market inputs, including benchmark yields, reported trades, broker/dealer quotes, bids, offers and other reference data. The Company uses quotes from external pricing service providers and other on-line quotation systems to verify the fair value of investments provided by its third-party pricing service providers. The Company reviews independent service auditor’s reports from its third-party pricing service providers particularly regarding the controls over pricing and valuation of financial instruments and ensure that its internal controls address certain control deficiencies, if any, and complementary user entity controls are in place. The Company does not have fair valued assets classified under Level 2 as of December 31, 2018 and 2017. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities and which reflect management’s best estimate of what market participants would use in pricing the asset or liability at the reporting date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. The Company’s financial instruments consist of cash and cash equivalents, short-term investments, and accounts payable, all of which are reported at their respective fair value on its consolidated balance sheets. The Company does not have fair valued assets classified under Level 3 as of December 31, 2018 and 2017. As of December 31, 2018, financial assets measured at fair value on a recurring basis are categorized in the table below based upon the lowest level of significant input to the valuations (in thousands): Assets at Fair Value as of December 31, 2018 Level 1 Level 2 Level 3 Total US treasury securities $ 265,393 $ - $ - $ 265,393 US government agency securities 120,978 - - 120,978 Total $ 386,371 $ - $ - $ 368,371 As of December 31, 2017, the Company had no financial assets measured at fair value on a recurring basis.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. Significant estimates include valuation of short-term investments, the useful lives of property and equipment, accounting for potential liabilities, the valuation allowance associated with the Company’s deferred tax assets, and the assumptions made in valuing stock instruments issued for services.
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of Iovance Biotherapeutics, Inc. and its wholly-owned subsidiary, Iovance Biotherapeutics GmbH (formerly Lion Biotechnologies GmbH). All intercompany accounts and transactions have been eliminated. The U.S. dollar is the functional currency for all the Company's consolidated operations.
Stock-Based Compensation	Stock-Based Compensation The Company periodically grants stock options and warrants to employees and non-employees in non-capital raising transactions as compensation for services rendered. The Company accounts for stock option grants to employees based on the authoritative guidance provided by the FASB where the value of the award is measured on the date of grant and recognized over the vesting period. The Company accounts for stock option grants to non-employees in accordance with the authoritative guidance of the FASB where the value of the stock compensation is determined based upon the measurement date at either a) the date at which a performance commitment is reached, or b) at the date at which the necessary performance to earn the equity instruments is complete. Non-employee stock-based compensation charges generally are amortized over the vesting period on a straight-line basis. In certain circumstances where there are no future performance requirements by the non-employee, option grants are immediately vested, and the total stock-based compensation charge is recorded in the period of the measurement date. The fair value of the Company's common stock option grants is estimated using a Black-Scholes option pricing model, which uses certain assumptions related to risk-free interest rates, expected volatility, expected life of the common stock options, and future dividends. Compensation expense is recorded based upon the value derived from the Black-Scholes option pricing model. The assumptions used in the Black-Scholes option pricing model could materially affect compensation expense recorded in future periods. The Company has in the past issued restricted shares of its common stock for share-based compensation programs. The Company measures the compensation cost with respect to restricted shares issued to employees based upon the estimated fair value of the equity instruments at the date of the grant, which is recognized as an expense over the period during which an employee is required to provide services in exchange for the award. The fair value of restricted stock units is based on the closing price of the Company’s common stock on the grant date. Total stock-based compensation expense related to all of the Company’s stock-based awards was recorded on the statements of operations as follows (in thousands): Years Ended December 31, 2018 2017 2016 Research and development $ 9,305 $ 5,270 $ 3,267 General and administrative 10,722 6,698 15,637 Total stock-based compensation expenses $ 20,027 $ 11,968 $ 18,904 Total stock-based compensation broken down based on each individual instrument was as follows (in thousands): Years Ended December 31, 2018 2017 2016 Stock option expense $ 19,758 $ 10,862 $ 16,453 Restricted stock award expense - 34 989 Restricted stock unit expense 269 1,072 1,462 Total stock-based compensation expenses $ 20,027 $ 11,968 $ 18,904
Research and Development Expenses	Research and Development Expenses Research and development expenses include personnel and facility-related expenses, outside contracted services including clinical trial costs, manufacturing and process development costs, research costs and other consulting services. Research and development costs are expensed as incurred. Nonrefundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and amortized over the period that the goods are delivered, or the related services are performed, subject to an assessment of recoverability. Clinical development costs are a significant component of research and development expenses. The Company has a history of contracting with third parties that perform various clinical trial activities on its behalf in connection with the ongoing development of its product candidates. The financial terms of these contracts are subject to negotiations and may vary from contract to contract and may result in uneven payment flow. The Company accrues and expenses costs for clinical trial activities performed by third parties based upon estimates of the percentage of work completed over the life of the individual trial in accordance with agreements established with contract research organizations and clinical trial sites. The Company determines its estimates through discussions with internal clinical personnel and outside service providers as to the progress or stage of completion of trials or services and the agreed upon fee to be paid for such services.
General and Administrative Expenses	General and Administrative Expenses General and administrative expenses consist primarily of salaries and other related costs, including stock-based compensation, for personnel in executive, finance, accounting, legal, investor relations, facilities, business development and human resources functions. Other significant costs include facility costs not otherwise included in research and development expenses, sublicense royalty expenses, legal fees relating to corporate matters, insurance, public company expenses relating to maintaining compliance with Nasdaq listing rules and Securities and Exchange Commission (“SEC”) requirements, investor relations costs, and fees for accounting and consulting services. General and administrative costs are expensed as incurred, and the Company accrues for services provided by third parties related to the above expenses by monitoring the status of services provided and receiving estimates from its service providers and adjusting its accruals as actual costs become known.
Income taxes	Income Taxes The Company accounts for income taxes using the asset and liability method whereby deferred tax assets are recognized for deductible temporary differences, and deferred tax liabilities are recognized for taxable temporary differences. Temporary differences are the differences between the reported amounts of assets and liabilities and their tax bases. Deferred tax assets are reduced by a valuation allowance when, in the opinion of management, it is more likely than not that some portion or all of the deferred tax assets will be realized. Deferred tax assets and liabilities are adjusted for the effects of changes in tax laws and rates on the date of enactment. ASC Topic 740-10-30, Income Taxes, clarifies the accounting for uncertainty in income taxes recognized in an enterprise’s financial statements and prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. ASC Topic 740-10-40 provides guidance on de-recognition, classification, interest and penalties, accounting in interim periods, disclosure, and transition. The Company will classify as income tax expense any interest and penalties. The Company has no material uncertain tax positions for any of the reporting periods presented.
Concentrations	Concentrations The Company is subject to credit risk from its portfolio of cash equivalents and short-term investments. Under its investment policy, it limits amounts invested in such securities by credit rating, maturity, industry group, investment type and issuer, except for securities issued by the U.S. government. The Company is not exposed to any significant concentrations of credit risk from these financial instruments. The goals of its investment policy, in order of priority, are as follows: safety and preservation of principal and diversification of risk; liquidity of investments sufficient to meet cash flow requirements; and a competitive after-tax rate of return. The Company maintains cash, cash equivalents and short-term investment balances at three financial institutions. At times, the amounts on deposit may exceed the federally insured limits. Management believes that the financial institutions which hold its cash are financially sound and, accordingly, minimal credit risk exists. As of December 31, 2018 and 2017, respectively, the Company’s cash balances were in excess of insured limits maintained at the financial institutions.
Preferred Stock	Preferred Stock The Company applies the accounting standards for distinguishing liabilities from equity when determining the classification and measurement of its preferred stock. Preferred shares subject to mandatory redemption are classified as liability instruments and are measured at fair value. Conditionally redeemable preferred shares (including preferred shares that feature redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control) are classified as temporary equity. At all other times, preferred shares are classified as stockholders’ equity.
Convertible Instruments	Convertible Instruments The Company applies the accounting standards for derivatives and hedging and for distinguishing liabilities from equity when accounting for hybrid contracts that feature conversion options. The accounting standards require companies to bifurcate conversion options from their host instruments and account for them as free-standing derivative financial instruments according to certain criteria. The criteria include circumstances in which (i) the economic characteristics and risks of the embedded derivative instrument are not clearly and closely related to the economic characteristics and risks of the host contract, (ii) the hybrid instrument that embodies both the embedded derivative instrument and the host contract is not re-measured at fair value under otherwise applicable generally accepted accounting principles with changes in fair value reported in earnings as they occur and (iii) a separate instrument with the same terms as the embedded derivative instrument would be considered a derivative instrument. The derivative is subsequently marked to market at each reporting date based on current fair value, with the changes in fair value reported in results of operations. Conversion options that contain variable settlement features such as provisions to adjust the conversion price upon subsequent issuances of equity or equity linked securities at exercise prices more favorable than that featured in the hybrid contract generally result in their bifurcation from the host instrument. The Company also records, when necessary, deemed dividends for the intrinsic value of the conversion options embedded in preferred stock based upon the difference between the fair value of the underlying common stock at the commitment date of the transaction and the effective conversion price embedded in the preferred stock.
Recent Accounting Standards	Recently Issued Accounting Standards Not Yet Adopted In February 2016, the FASB issued Accounting Standard Update (ASU) No. 2016-02, Leases (Topic 842), which establishes a new lease accounting model for lessees. The updated guidance requires an entity to recognize assets and liabilities arising from a lease for both financing and operating leases, along with additional qualitative and quantitative disclosures. In June 2018, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, Leases, which further clarifies how to apply certain aspects of the new lease standard. Topic 842 is effective for fiscal years, and interim periods within those years, beginning after December 15, 2018, with early adoption permitted. The Company adopted Topic 842 on January 1, 2019, using a modified retrospective approach as applied to lease existing as of or entered into after the adoption date. Topic 842 provides a number of optional practical expedients and accounting policy elections. The Company elected the package of practical expedients requiring no reassessment of whether any expired or existing contracts are or contain leases, the lease classification of any expired or existing leases, or initial direct costs for any existing leases. The Company is in the final process of implementing a new lease accounting policy and updating its controls and procedures for maintaining and accounting for its lease portfolio under the new guidance. Upon adoption of Topic 842, the Company expects recognition of additional assets and corresponding liabilities pertaining to its operating leases on its consolidated balance sheets. The Company does not expect the adoption of the new standard to have a significant impact on its consolidated statements of operations and cash flows. In June 2018, the FASB issued ASU No. 2018-07, Compensation- Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, which eliminates the separate accounting model for nonemployee share-based payment awards and generally requires companies to account for share-based payment transactions with nonemployees in the same way as share-based payment transactions with employees. Under the new guidance, nonemployee share-based payment transactions are measured at the grant-date fair value and are no longer remeasured at the then-current fair values at each reporting date until the share options have vested. The amended guidance is effective for fiscal years beginning after December 15, 2018, with early adoption permitted. The Company plans to adopt this ASU on January 1, 2019. The guidance requires a modified-retrospective approach in transition. The Company compared the cumulative amounts that were recorded for its nonemployee share-based payments through December 31, 2018 immediately preceding the date of adoption to the cumulative amounts that should be recognized at the adoption date and will record a cumulative effect of the transition adjustment of $0.3 million as an adjustment to retained earnings as of the date of adoption, January 1, 2019. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework- Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates disclosure requirement regarding transfers between level 1 and level 2 of the fair value of hierarchy, however, adds disclosure requirements on the range and weighted average used to develop significant unobservable inputs for level 3 fair value measurements. The guidance is effective for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years, with early adoption permitted. The Company plans to adopt this ASU on January 1, 2020. The Company expects the impact of the adoption of this standard on its financial statements to be immaterial. In August 2018, the Security Exchange Commission (SEC) adopted the final rule under SEC Release No. 33-10532, “Disclosure Update and Simplification,” amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders’ equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders’ equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. This final rule is effective on November 5, 2018. The Company is evaluating the impact of this guidance on its consolidated financial statements. The Company anticipates its first presentation of changes in stockholders’ equity will be included in its Form 10-Q for the quarter ended March 31, 2019.
Segment reporting	Segment reporting The Company operates in one segment, focused on developing and commercializing ACT using autologous TIL for the treatment of metastatic melanoma and other solid cancers.
Subsequent Events	Subsequent Events Management of the Company evaluates events that have occurred after the balance sheet date but before the financial statements are issued. Based upon the review, management did not identify any recognized or non-recognized subsequent events which would have required an adjustment or disclosure in the financial statements.
Reclassifications	Reclassifications Certain amounts within the balance sheets for the prior period have been reclassified to conform with the current period presentation. These reclassifications had no impact on the Company's previously reported financial position or cash flows for any of the periods presented. The long-term portion of deferred rent liability as of December 31, 2017 was separately presented as long-term in the 2017 consolidated balance sheet included in this annual report filed on Form10-K.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	At December 31, 2018, 2017 and 2016, the following outstanding common stock equivalents have been excluded from the calculation of net loss per share because their impact would be anti-dilutive. As of December 31, 2018 2017 2016 Stock options 6,889,287 6,072,368 6,233,150 Warrants - 6,301,216 6,566,216 Series A Convertible Preferred* 97,000 847,000 847,000 Series B Convertible Preferred* 5,854,845 7,378,241 7,946,673 Restricted stock awards - - 7,084 Restricted stock units 68,742 114,582 550,000 12,909,874 20,713,407 22,150,123 *on an as-converted basis
Schedule of Assets Measured at Fair Value	As of December 31, 2018, financial assets measured at fair value on a recurring basis are categorized in the table below based upon the lowest level of significant input to the valuations (in thousands): Assets at Fair Value as of December 31, 2018 Level 1 Level 2 Level 3 Total US treasury securities $ 265,393 $ - $ - $ 265,393 US government agency securities 120,978 - - 120,978 Total $ 386,371 $ - $ - $ 368,371
Schedule of Stock-Based Compensation	Total stock-based compensation expense related to all of the Company’s stock-based awards was recorded on the statements of operations as follows (in thousands): Years Ended December 31, 2018 2017 2016 Research and development $ 9,305 $ 5,270 $ 3,267 General and administrative 10,722 6,698 15,637 Total stock-based compensation expenses $ 20,027 $ 11,968 $ 18,904
Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan	Total stock-based compensation broken down based on each individual instrument was as follows (in thousands): Years Ended December 31, 2018 2017 2016 Stock option expense $ 19,758 $ 10,862 $ 16,453 Restricted stock award expense - 34 989 Restricted stock unit expense 269 1,072 1,462 Total stock-based compensation expenses $ 20,027 $ 11,968 $ 18,904

CASH AND CASH EQUIVALENTS, AN_2

CASH AND CASH EQUIVALENTS, AND SHORT-TERM INVESTMENTS (Tables)	12 Months Ended
	Dec. 31, 2018
Cash, Cash Equivalents, and Short-term Investments [Abstract]
Schedule of Cash, Money Market Funds and Short-Term Investments	Cash equivalents, and short-term investments consist of the following (in thousands): December 31, December 31, 2018 2017 Cash equivalents - Money market funds $ 25,968 $ 91,281 Cash equivalents total $ 25,968 $ 91,281
Schedule of Unrealized Gains and Losses	Cash equivalents in the tables above exclude cash demand deposits of $56.2 million and $54.1 million as of December 31, 2018 and December 31, 2017, respectively (in thousands). December 31, December 31, Short-term Investments 2018 2017 US treasury securities $ 265,393 $ - US government agency securities 120,978 - Short-term investments total $ 386,371 $ - The cost and fair value of cash equivalents and short-term investments at December 31, 2018 were as follows (in thousands): Gross Gross Unrealized Unrealized As of December 31, 2018 Cost Accretion Gains Losses Fair Value US treasury securities $ 264,619 $ 813 $ 19 $ (58 ) $ 265,393 US government agency securities 120,653 328 21 (24 ) 120,978 Total $ 385,272 $ 1,141 $ 40 $ (82 ) $ 386,371

BALANCE SHEET COMPONENTS (Table

BALANCE SHEET COMPONENTS (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment	Property and equipment, net consists of the following (in thousands): December 31, December 31, 2018 2017 Lab equipment $ 4,160 $ 3,207 Leasehold improvements 1,776 1,726 Computer equipment 337 349 Office furniture and equipment 263 188 Construction in progress 107 13 Total Property and equipment, cost 6,643 5,483 Less: Accumulated depreciation and amortization (3,960 ) (3,033 ) property and equipment, net $ 2,683 $ 2,450
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): December 31, December 31, 2018 2017 Accrued payroll and employee related expenses $ 4,113 $ 2,613 Legal and related services 825 935 Clinical related 3,424 3,310 Manufacturing related 2,684 876 Deferred rent - current 124 133 Accrued other 489 496 $ 11,659 $ 8,363

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Schedule of Stockholders' Equity Note, Warrants or Rights	A summary of the status of stock warrants at December 31, 2018 and the changes during the three years then ended, is presented in the following table. Weighted Weighted Aggregate Shares Average Average Intrinsic Under Exercise Remaining Value Warrants Price Life (in thousands) Outstanding at January 1, 2016 7,202,216 $ 2.51 Issued - - Exercised (592,132 ) 2.50 Expired/Cancelled (43,868 ) 2.51 Outstanding at December 31, 2016 6,566,216 $ 2.51 Issued - - Exercised (265,000 ) 2.50 Expired/Cancelled - - Outstanding at December 31, 2017 6,301,216 $ 2.51 Issued - - Exercised (6,301,216 ) 2.51 Expired/Cancelled - - Outstanding at December 31, 2018 - $ - - $ -

STOCK BASED COMPENSATION (Table

STOCK BASED COMPENSATION (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Status of Stock Options	A summary of the status of stock options at December 31, 2018, and the changes during the three years then ended, is presented in the following table: Weighted Weighted Average Aggregate Number Average Remaining Intrinsic of Exercise Contractual Value Options Price Life (in thousands) Outstanding at January 1, 2016 2,693,237 $ 8.12 Issued 4,407,983 6.86 Exercised (100,480 ) 6.23 Expired/Cancelled (767,590 ) 8.12 Outstanding at December 31, 2016 6,233,150 $ 7.24 Issued 2,188,800 6.68 Exercised (1,011,284 ) 5.55 Expired/Cancelled (1,338,298 ) 6.79 Outstanding at December 31, 2017 6,072,368 $ 7.42 Issued 2,960,620 14.73 Exercised (1,336,514 ) 7.45 Expired/Cancelled (807,187 ) 10.04 Outstanding at December 31, 2018 6,889,287 $ 10.25 8.30 years $ 7,186 Exercisable at December 31, 2018 3,118,910 $ 7.88 7.56 years $ 4,745
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The following table summarizes the assumptions relating to options granted pursuant to the Company’s equity incentive plans for the years ended December 31, 2018, 2017, and 2016: Years Ended December 31, 2018 2017 2016 Expected dividend yield 0% 0% 0% Risk-free interest rate 2.97% - 2.27% 2.34% - 1.72% 2.16% - 1.18% Expected term (in years) 6.50 - 5.13 6.50 - 5.13 6.50 - 5.07 Expected volatility 200.28% - 167.54% 209.69% - 190.46% 213.60% - 189.40%
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding and Exercisable	A summary of outstanding and exercisable stock options as of December 31, 2018 is as follows: Options Outstanding Options Exercisable Range of Exercise Prices Number of Shares Weighted Average Remaining Contractual Life Weighted Average Exercise Price Per Share Number of Shares Weighted Average Remaining Contractual Life Weighted Average Exercise Price Per Share $5.05 - $5.87 1,123,800 7.79 $ 5.55 743,376 7.69 $ 5.56 $5.87 - $7.45 758,109 7.67 6.92 473,398 7.18 6.94 $7.46 - $7.55 897,625 7.87 7.55 662,832 7.87 7.55 $7.56 - $8.17 804,283 7.75 7.86 522,596 7.26 7.84 $8.18 - $9.15 712,500 7.69 8.99 502,708 7.66 9.10 $9.16 - $13.85 732,850 9.17 11.66 123,750 6.45 11.05 $13.86 - $16.25 690,700 9.43 15.13 81,250 9.38 15.26 $16.26 - $16.80 961,420 9.10 16.66 - - - $16.81 - $115.00 206,000 8.96 21.24 7,000 2.84 94.01 $115.01 117.00 2,000 2.32 117.00 2,000 2.32 117.00 6,889,287 8.30 $ 10.25 3,118,910 7.56 $ 7.88
Schedule of Nonvested Restricted Stock Units Activity	The following table summarizes restricted common stock awards activity: Weighted Average Grant Date Number of Share Fair Value Non-vested shares, January 1, 2016 321,252 $ 6.96 Granted - - Vested (274,167 ) 6.90 Forfeited (40,001 ) 7.02 Non-vested shares, December 31, 2016 7,084 $ 6.48 Granted - - Vested (7,084 ) 6.48 Forfeited - - Non-vested shares, December 31, 2017 - - Granted - $ - Vested - - Forfeited - - Non-vested shares, December 31, 2018 - $ -

INCOME TAXES (Tables)

INCOME TAXES (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets and Liabilities	Net deferred tax assets (liabilities) are summarized as follows (in thousands): As of December 31, 2018 2017 Deferred income tax asset: Net operating loss carry forward $ 56,971 $ 33,300 Stock-based compensation 5,823 4,568 Tax credit carry forwards 14,356 9,323 Reserves and accruals 1,049 733 Deferred tax assets before valuation allowance 78,199 47,924 Less: valuation allowance (78,146 ) (47,849 ) Net deferred income tax assets 53 75 Deferred tax liabilities: Depreciation and amortization (53 ) (75 ) Net deferred tax assets (liabilities) $ - $ -
Schedule of Effective Income Tax Rate Reconciliation	Reconciliation of the effective income tax rate to the U.S. statutory rate is as follows: Years ended December 31, 2018 2017 2016 Federal statutory tax rate (21 )% (34 )% (34 )% Orphan Drug & Research credits (3 ) 0 (8 ) Permanent and other differences 1 4 4 Tax rate change - 23 - State tax, net of federal benefit (1 ) - (4 ) (24 )% (7 )% (42 )% Valuation allowance 24 % 7 % 42 % Effective tax rate - % - % - %
Schedule of Components of Income Tax Expense (Benefit)	The components of income tax expense (benefit) are as follows (in thousands): Years Ended December 31, 2018 2017 2016 Federal: Current $ - $ - $ - Deferred (28,277 ) (7,391 ) (19,050 ) State and Local Current - - - Deferred (2,020 ) 944 (3,007 ) Change in Valuation Allowance 30,297 6,447 22,057 Total income tax expense (benefit) $ - $ - $ -
Schedule of Unrecognized Tax Benefits	A reconciliation of the beginning and ending balances of the unrecognized tax benefits during the years ended December 31, 2018, 2017 and 2016 is as follows (in thousands): Years Ended December 31, 2018 2017 2016 Unrecognized benefit - beginning of period $ 4,111 $ - $ - Gross decreases - prior period tax positions 118 2,780 - Gross increase current period tax positions 2,115 1,331 - Unrecognized benefit - end of period $ 6,344 $ 4,111 $ -

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Contractual Obligation, Fiscal Year Maturity Schedule [Table Text Block]	As of December 31, 2018, the Company's future minimum lease payments under non-cancelable operating leases are as follows (in thousands): Payments due by period Contractual Obligations Total 2019 2020 2021 2022 Thereafter Facility leases $ 3,014 $ 1,373 $ 1,223 $ 418 $ - $ - CMO contractual obligations 28,587 17,992 7,690 2,324 581 - Total $ 31,601 $ 19,365 $ 8,913 $ 2,742 $ 581 $ -

QUARTERLY UNAUDITED RESULTS (Ta

QUARTERLY UNAUDITED RESULTS (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information	The results of operations by quarter for the years ended December 31, 2018 and 2017 are as follow: 2018 2017 (in thousands, except per share information) Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Revenue $ - $ - $ - $ - - $ - $ - $ - Net loss attributable to common stockholder $ (26,515 ) $ (30,660 ) $ (33,830 ) $ (32,575 ) (20,684 ) $ (23,377 ) $ (22,149 ) $ (25,854 ) Net loss per share, basic and diluted $ (0.31 ) $ (0.34 ) $ (0.36 ) $ (0.27 ) (0.33 ) $ (0.37 ) $ (0.35 ) $ (0.36 ) Weighted average share used in computing net loss per share, basic and diluted 84,350 90,236 95,077 119,085 62,286 62,457 63,332 72,794

GENERAL ORGANIZATION, BUSINES_2

GENERAL ORGANIZATION, BUSINESS AND LIQUIDITY (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended								12 Months Ended
	Oct. 17, 2018	Jan. 31, 2018	Sep. 30, 2017	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	Dec. 31, 2015
Net Income (Loss) Attributable to Parent				$ (32,575)	$ (33,830)	$ (30,660)	$ (26,515)	$ (25,854)	$ (22,149)	$ (23,377)	$ (20,684)	$ (123,580)	$ (92,064)	$ (52,894)
Cash and Cash Equivalents, at Carrying Value				82,152				145,373				82,152	145,373	106,717	$ 33,587
Stock Issued During Period, Shares, New Issues	25,300,000
Proceeds from Issuance of Common Stock	$ 236,700											398,817	53,662	95,685
Shares Issued, Price Per Share	$ 9.97
Net Cash Provided by (Used in) Operating Activities												(101,249)	(78,709)	$ (32,668)
Available-for-sale Securities, Current				$ 386,371				$ 0				$ 386,371	$ 0
Underwriter [Member]
Stock Issued During Period, Shares, New Issues	3,300,000
IPO [Member]
Stock Issued During Period, Shares, New Issues		15,000,000	8,846,154
Proceeds from Issuance of Common Stock		$ 162,000	$ 53,700
Shares Issued, Price Per Share		$ 11.50	$ 6.50						$ 6.50
IPO [Member] | Underwriter [Member]
Stock Issued During Period, Shares, New Issues		1,956,521	1,153,846
Proceeds from Issuance of Common Stock		$ 162,000	$ 57,500
Common Stock [Member]
Stock Issued During Period, Shares, New Issues	25,300,000											40,300,000	8,846,154

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES (Details) - shares		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		12,909,874	20,713,407	22,150,123
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		6,889,287	6,072,368	6,233,150
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		0	6,301,216	6,566,216
Restricted Stock Awards [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		0	0	7,084
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount		68,742	114,582	550,000
Series A Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	[1]	97,000	847,000	847,000
Series B Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	[1]	5,854,845	7,378,241	7,946,673
[1]	on an as-converted basis

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES (Details 1) $ in Thousands	Dec. 31, 2018USD ($)
Assets, Fair Value Disclosure	$ 368,371
US treasury securities [Member]
Assets, Fair Value Disclosure	265,393
US Government agency securities [Member]
Assets, Fair Value Disclosure	120,978
Fair Value, Inputs, Level 1 [Member]
Assets, Fair Value Disclosure	386,371
Fair Value, Inputs, Level 1 [Member] | US treasury securities [Member]
Assets, Fair Value Disclosure	265,393
Fair Value, Inputs, Level 1 [Member] | US Government agency securities [Member]
Assets, Fair Value Disclosure	120,978
Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure	0
Fair Value, Inputs, Level 2 [Member] | US treasury securities [Member]
Assets, Fair Value Disclosure	0
Fair Value, Inputs, Level 2 [Member] | US Government agency securities [Member]
Assets, Fair Value Disclosure	0
Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure	0
Fair Value, Inputs, Level 3 [Member] | US treasury securities [Member]
Assets, Fair Value Disclosure	0
Fair Value, Inputs, Level 3 [Member] | US Government agency securities [Member]
Assets, Fair Value Disclosure	$ 0

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES (Details 2) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost, Total	$ 20,027	$ 11,968	$ 18,904
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost, Total	9,305	5,270	3,267
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost, Total	$ 10,722	$ 6,698	$ 15,637

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES (Details 3) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost	$ 20,027	$ 11,968	$ 18,904
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost	19,758	10,862	16,453
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost	0	34	989
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost	$ 269	$ 1,072	$ 1,462

SUMMARY OF SIGNIFICANT ACCOUN_8

SUMMARY OF SIGNIFICANT ACCOUNTING PRACTICES (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Jan. 01, 2019
Subsequent Event [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption		$ 0.3
Computer Equipment [Member]
Property, Plant and Equipment, Useful Life	2 years
Office Furniture and Equipment [Member]
Property, Plant and Equipment, Useful Life	5 years
Lab Equipment [Member]
Property, Plant and Equipment, Useful Life	5 years
Leasehold Improvements [Member]
Property, Plant and Equipment, Estimated Useful Lives	Lesser of the remaining economic life of the asset or the lease-term

CASH AND CASH EQUIVALENTS, AN_3

CASH AND CASH EQUIVALENTS, AND SHORT-TERM INVESTMENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash equivalents total	$ 82,152	$ 145,373	$ 106,717	$ 33,587
Demand Deposits [Member]
Cash equivalents total	56,200	54,100
Money market funds [Member]
Cash equivalents total	$ 25,968	$ 91,281

CASH AND CASH EQUIVALENTS, AN_4

CASH AND CASH EQUIVALENTS, AND SHORT-TERM INVESTMENTS (Details 1) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Cash, Cash Equivalents, and Short-term Investments	$ 386,371	$ 0
US Treasury Securities [Member]
Cash, Cash Equivalents, and Short-term Investments	265,393	0
US government agency securities [Member]
Cash, Cash Equivalents, and Short-term Investments	$ 120,978	$ 0

CASH AND CASH EQUIVALENTS, AN_5

CASH AND CASH EQUIVALENTS, AND SHORT-TERM INVESTMENTS (Details 2) $ in Thousands	Dec. 31, 2018USD ($)
Cost	$ 385,272
Accretion	1,141
Gross Unrealized Gains	40
Gross Unrealized Losses	(82)
Fair Value	386,371
US treasury securities [Member]
Cost	264,619
Accretion	813
Gross Unrealized Gains	19
Gross Unrealized Losses	(58)
Fair Value	265,393
US Government agency securities [Member]
Cost	120,653
Accretion	328
Gross Unrealized Gains	21
Gross Unrealized Losses	(24)
Fair Value	$ 120,978

BALANCE SHEET COMPONENTS (Detai

BALANCE SHEET COMPONENTS (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Total Property and equipment, cost	$ 6,643	$ 5,483
Less: Accumulated depreciation and amortization	(3,960)	(3,033)
Property and equipment, net	2,683	2,450
Lab Equipment [Member]
Total Property and equipment, cost	4,160	3,207
Leasehold Improvements [Member]
Total Property and equipment, cost	1,776	1,726
Computer Equipment [Member]
Total Property and equipment, cost	337	349
Office Furniture and Equipment [Member]
Total Property and equipment, cost	263	188
Construction in Progress [Member]
Total Property and equipment, cost	$ 107	$ 13

BALANCE SHEET COMPONENTS (Det_2

BALANCE SHEET COMPONENTS (Details 1) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accrued payroll and employee related expenses	$ 4,113	$ 2,613
Legal and related services	825	935
Clinical related	3,424	3,310
Manufacturing related	2,684	876
Deferred rent - current	124	133
Accrued other	489	496
Accrued liabilities	$ 11,659	$ 8,363

BALANCE SHEET COMPONENTS (Det_3

BALANCE SHEET COMPONENTS (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Depreciation	$ 1	$ 1	$ 1

STOCKHOLDERS' EQUITY (Details)

STOCKHOLDERS' EQUITY (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Shares Under Warrants
Outstanding, ending balance	6,889,287
Weighted Average Exercise Price
Outstanding, ending balance	$ 10.25
Weighted Average Remaining Contractual Life
Outstanding	8 years 3 months 18 days
Warrant [Member]
Shares Under Warrants
Outstanding, beginning balance	6,301,216	6,566,216	7,202,216
Issued	0	0	0
Exercised	(6,301,216)	(265,000)	(592,132)
Expired/Cancelled	0	0	(43,868)
Outstanding, ending balance	0	6,301,216	6,566,216
Weighted Average Exercise Price
Outstanding, beginning balance	$ 2.51	$ 2.51	$ 2.51
Issued	0	0	0
Exercised	2.51	2.50	2.50
Expired/Cancelled	0	0	2.51
Outstanding, ending balance	$ 0	$ 2.51	$ 2.51
Weighted Average Remaining Contractual Life
Outstanding	0 years
Aggregate Intrinsic Value
Outstanding, ending balance	$ 0

STOCKHOLDERS' EQUITY (Details T

STOCKHOLDERS' EQUITY (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	Jun. 07, 2016	Jun. 02, 2016	Oct. 17, 2018	Jan. 31, 2018	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues			25,300,000
Proceeds from Issuance of Common Stock			$ 236,700			$ 398,817	$ 53,662	$ 95,685
Shares Issued, Price Per Share			$ 9.97
Other Preferred Stock Dividends and Adjustments						$ 0	$ 0	$ 49,454
Underwriter [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues			3,300,000
Proceeds From Issuance Of Common Stock Gross			$ 252,200
Common Stock [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues			25,300,000			40,300,000	8,846,154
Conversion of Stock, Shares Issued						5,854,845
Conversion of Stock, Shares Converted						1,523,396	568,432	3,421,960
Common Stock [Member] | Issuance Of Common Stock Upon Conversion Of Preferred Stock [Member]
Class of Stock [Line Items]
Conversion of Stock, Shares Issued						1,500
Conversion of Stock, Shares Converted						750,000
2016 Private Placement [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues	9,684,000
Proceeds from Issuance of Private Placement		$ 100,000
Proceeds from Issuance or Sale of Equity	$ 95,700
IPO [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues				15,000,000	8,846,154
Proceeds from Issuance of Common Stock				$ 162,000	$ 53,700
Shares Issued, Price Per Share				$ 11.50	$ 6.50
IPO [Member] | Underwriter [Member]
Class of Stock [Line Items]
Stock Issued During Period, Shares, New Issues				1,956,521	1,153,846
Proceeds from Issuance of Common Stock				$ 162,000	$ 57,500
Series A Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Conversion of Stock, Shares Issued						500
Preferred Stock, Shares Authorized						17,000	17,000
Preferred Stock, Shares Outstanding						194
Series A Convertible Preferred Stock [Member] | Common Stock [Member]
Class of Stock [Line Items]
Conversion of Stock, Shares Converted						97,000
Series A Convertible Preferred Stock [Member] | Common Stock [Member] | Issuance Of Common Stock Upon Conversion Of Preferred Stock [Member]
Class of Stock [Line Items]
Conversion of Stock, Shares Issued							0	0
Series A Convertible Preferred Stock [Member] | Private Placement [Member]
Class of Stock [Line Items]
Sale of Stock, Price Per Share						$ 2
Preferred Stock, Par or Stated Value Per Share						$ 1,000
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized						11,500,000	11,500,000
Preferred Stock, Par or Stated Value Per Share						$ 0.001	$ 0.001
Preferred Stock, Shares Outstanding						5,854,845	7,378,241
Series B Preferred Stock [Member] | 2016 Private Placement [Member]
Class of Stock [Line Items]
Convertible Price Per Shares	$ 4.75
Sock Issued During Period Preferred Stock Shares	11,368,633
Shares Issued, Price Per Share	$ 4.75
Other Preferred Stock Dividends and Adjustments						$ 49,500
Series B Convertible Preferred Stock [Member]
Class of Stock [Line Items]
Conversion of Stock, Shares Converted						1,523,396	568,432	3,421,960
Preferred Stock, Shares Authorized						11,500,000
Preferred Stock, Par or Stated Value Per Share						$ 4.75
Convertible Price Per Shares						$ 4.75
Blank Check [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized						50,000,000

STOCK BASED COMPENSATION (Detai

STOCK BASED COMPENSATION (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Options
Outstanding, ending balance	6,889,287
Exercisable	3,118,910
Weighted Average Exercise Price
Outstanding, ending balance	$ 10.25
Exercisable	$ 7.88
Weighted Average Remaining Contractual Life
Outstanding	8 years 3 months 18 days
Exercisable	7 years 6 months 22 days
Employee Stock Option [Member]
Number of Options
Outstanding, beginning balance	6,072,368	6,233,150	2,693,237
Issued	2,960,620	2,188,800	4,407,983
Exercised	(1,336,514)	(1,011,284)	(100,480)
Expired/Cancelled	(807,187)	(1,338,298)	(767,590)
Outstanding, ending balance	6,889,287	6,072,368	6,233,150
Exercisable	3,118,910
Weighted Average Exercise Price
Outstanding, beginning balance	$ 7.42	$ 7.24	$ 8.12
Issued	14.73	6.68	6.86
Exercised	7.45	5.55	6.23
Expired/Cancelled	10.04	6.79	8.12
Outstanding, ending balance	10.25	$ 7.42	$ 7.24
Exercisable	$ 7.88
Weighted Average Remaining Contractual Life
Outstanding	8 years 3 months 18 days
Exercisable	7 years 6 months 22 days
Aggregate Intrinsic Value
Outstanding, beginning balance	$ 7,186
Exercisable	$ 4,745

STOCK BASED COMPENSATION (Det_2

STOCK BASED COMPENSATION (Details 1)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Expected dividend yield	0.00%	0.00%	0.00%
Maximum [Member]
Risk-free interest rate	2.97%	2.34%	2.16%
Expected term (in years)	6 years 6 months	6 years 6 months	6 years 6 months
Expected volatility	200.28%	209.69%	213.60%
Minimum [Member]
Risk-free interest rate	2.27%	1.72%	1.18%
Expected term (in years)	5 years 1 month 17 days	5 years 1 month 17 days	5 years 25 days
Expected volatility	167.54%	190.46%	189.40%

STOCK BASED COMPENSATION (Det_3

STOCK BASED COMPENSATION (Details 2)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	6,889,287
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	8 years 3 months 18 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 10.25
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	3,118,910
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	7 years 6 months 22 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 7.88
Range Of Exercise Prices $5.05 - $5.87 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	1,123,800
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	7 years 9 months 14 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 5.55
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	743,376
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	7 years 8 months 8 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 5.56
Range Of Exercise Prices $5.87 - $7.45 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	758,109
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	7 years 8 months 1 day
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 6.92
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	473,398
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	7 years 2 months 5 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 6.94
Range Of Exercise Prices $7.46 - $7.55 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	897,625
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	7 years 10 months 13 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 7.55
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	662,832
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	7 years 10 months 13 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 7.55
Range Of Exercise Prices $7.56 - $8.17 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	804,283
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	7 years 9 months
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 7.86
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	522,596
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	7 years 3 months 4 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 7.84
Range Of Exercise Prices $8.18 - $9.15 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	712,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	7 years 8 months 8 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 8.99
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	502,708
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	7 years 7 months 28 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 9.10
Range Of Exercise Prices $9.16 - $13.85 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	732,850
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	9 years 2 months 1 day
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 11.66
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	123,750
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	6 years 5 months 12 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 11.05
Range Of Exercise Prices $13.86 - $16.25 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	690,700
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	9 years 5 months 5 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 15.13
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	81,250
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	9 years 4 months 17 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 15.26
Range Of Exercise Prices $16.26 - $16.80 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	961,420
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	9 years 1 month 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 16.66
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	0 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 0
Range Of Exercise Prices $16.81 - $115.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	206,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	8 years 11 months 16 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 21.24
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	7,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	2 years 10 months 2 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 94.01
Range Of Exercise Prices $115.01 - $117.00 [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number | shares	2,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term	2 years 3 months 25 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price | $ / shares	$ 117
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number | shares	2,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	2 years 3 months 25 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price | $ / shares	$ 117

STOCK BASED COMPENSATION (Det_4

STOCK BASED COMPENSATION (Details 3) - $ / shares	Jun. 02, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Number of Shares
Non-vested shares, Beginning Balance		0	7,084	321,252
Granted		0	0	0
Vested	(137,500)	0	(7,084)	(274,167)
Forfeited		0	0	(40,001)
Non-vested shares, Ending balance		0	0	7,084
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, Beginning Balance			$ 6.48	$ 6.96
Granted			0	0
Vested			$ 6.48	6.90
Forfeited				7.02
Weighted Average Grant Date Fair Value, Ending balance				$ 6.48

STOCK BASED COMPENSATION (Det_5

STOCK BASED COMPENSATION (Details Textual) - USD ($) $ / shares in Units, $ in Thousands

Jun. 02, 2016

Aug. 31, 2013

Dec. 31, 2018

Dec. 31, 2017

Dec. 31, 2016

Apr. 22, 2018

Apr. 16, 2016

Dec. 31, 2015

Apr. 10, 2015

Nov. 30, 2014

Aug. 20, 2014

Oct. 14, 2011

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

Allocated Share-based Compensation Expense

$ 1,000

Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized

$ 35,000

Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition

1 year 9 months 25 days

Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value

$ 2,300

$ 2,600

$ 200

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

0

0

0

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

$ 0

$ 0

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period

137,500

0

7,084

274,167

Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value

$ 14.44

$ 6.58

$ 6.78

Share-based Compensation Arrangement by Share-based Payment Award, Description

an amendment to increase the number options or other awards that can be granted to any one person during a twelve (12) month period from 50,000 shares to 300,000 shares.

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number

0

0

7,084

321,252

Share-based Compensation

$ 20,027

$ 11,968

$ 18,904

Restricted Common Stock [Member]

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

Allocated Share-based Compensation Expense

300

$ 1,100

$ 1,500

Restricted Stock [Member]

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

Allocated Share-based Compensation Expense

$ 400

Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition

1 year 5 months 1 day

Restricted Stock [Member] | Chief Executive Officer [Member]

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

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period

550,000

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value

$ 5.87

First Anniversary [Member] | Restricted Stock [Member]

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

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period

137,500

Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period

36 months

Satisfaction Of Clinical Trial Milestones [Member] | Restricted Stock [Member]

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

Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period

275,000

2011 Equity Incentive Plan [Member]

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

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant

376,240

Common Stock, Capital Shares Reserved for Future Issuance

1,700,000

1,900,000

180,000

2011 Equity Incentive Plan [Member] | Minimum [Member]

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

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant

180,000

2014 Equity Incentive Plan [Member]

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

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized

4,000,000

2,350,000

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant

579,809

2014 Equity Incentive Plan [Member] | Maximum [Member]

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

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized

9,000,000

2018 Equity Incentive Plan [Member]

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

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized

6,000,000

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant

6,000,000

EMPLOYEE BENEFIT PLAN (Details

EMPLOYEE BENEFIT PLAN (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Contribution Plan, Cost	$ 0.5	$ 0.3	$ 0.1

SEPARATION AGREEMENTS (Details

SEPARATION AGREEMENTS (Details Textual) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2016
Dr. Elma Hawkins [Member]
Severance Costs	$ 0.5
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost		$ 5
Molly Henderson [Member]
Severance Costs	$ 0.4
Share-based Compensation Arrangement by Share-based Payment Award Accelerated Compensation Cost		$ 4.5

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred income tax asset:
Net operating loss carry forward	$ 56,971	$ 33,300
Stock-based compensation	5,823	4,568
Tax credit carryforwards	14,356	9,323
Reserves and accruals	1,049	733
Deferred tax assets before valuation allowance	78,199	47,924
Less: valuation allowance	(78,146)	(47,849)
Net deferred income tax assets	53	75
Deferred tax liabilities:
Depreciation and amortization	(53)	(75)
Net deferred tax assets (liabilities)	$ 0	$ 0

INCOME TAXES (Details 1)

INCOME TAXES (Details 1)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Federal statutory tax rate	(21.00%)	(34.00%)	(34.00%)
Orphan Drug & Research credits	(3.00%)	0.00%	(8.00%)
Permanent and other differences	1.00%	4.00%	4.00%
Tax rate change	0.00%	23.00%	0.00%
State tax, net of federal benefit	(1.00%)	0.00%	(4.00%)
Effective Income Tax Rate Reconciliation Expected Rate Total	(24.00%)	(7.00%)	(42.00%)
Valuation allowance	24.00%	7.00%	42.00%
Effective tax rate	0.00%	0.00%	0.00%

INCOME TAXES (Details 2)

INCOME TAXES (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Federal:
Current	$ 0	$ 0	$ 0
Deferred	(28,277)	(7,391)	(19,050)
State and Local
Current	0	0	0
Deferred	(2,020)	944	(3,007)
Change in Valuation Allowance	30,297	6,447	22,057
Total income tax expense (benefit)	$ 0	$ 0	$ 0

INCOME TAXES (Details 3)

INCOME TAXES (Details 3) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Unrecognized benefit-beginning of period	$ 4,111	$ 0	$ 0
Gross decreases-prior period tax positions	118	2,780	0
Gross increases-current period tax positions	2,115	1,331	0
Unrecognized benefit-end of period	$ 6,344	$ 4,111	$ 0

INCOME TAXES (Details Textual)

INCOME TAXES (Details Textual) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Contingency [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ 30.3	$ 6.4	$ 22.1
Increase (Decrease) in Deferred Income Taxes	$ 20.8
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%	34.00%	34.00%
Scenario, Plan [Member]
Income Tax Contingency [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		21.00%
Domestic Tax Authority [Member]
Income Tax Contingency [Line Items]
Operating Loss Carryforwards		$ 251.5
Operating Loss Carryforwards, Commencement Year		2,027
Operating Loss Carryforwards, Expiration Year		2,038
Operating Loss Carry forwards Having Definite Expire life Value		$ 142.4
Operating Loss Carry forwards Having Indefinite Expire life Value		109
State and Local Jurisdiction [Member]
Income Tax Contingency [Line Items]
Operating Loss Carryforwards		$ 88.9
Operating Loss Carryforwards, Commencement Year		2,031
Operating Loss Carryforwards, Expiration Year		2,038

LICENSES AND AGREEMENTS (Detail

LICENSES AND AGREEMENTS (Details Textual) - USD ($)	Sep. 14, 2016	Jun. 30, 2018	Apr. 17, 2017	Nov. 30, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 31, 2017
Research and Development Expense					$ 99,828,000	$ 71,615,000	$ 26,941,000
Research and Development Arrangement [Member]
Prepaid Expense, Current								$ 1.4
Strategic Alliance Agreement [Member]
Research and Development Expense					800,000
Research Collaboration And Clinical Grant Agreements [Member]
Research and Development Expense					1,200,000	1,200,000	700,000
Maximum [Member] | Research and Development Arrangement [Member]
Research and Development Arrangement, Contract to Perform for Others, Costs Incurred, Gross			$ 14,200,000
KarolinskaUniversityHospital [Member]
Research and Development Expense					400,000	300,000	100,000
Payments For Clinical Trials Agreement							1,600,000
Proceeds From Refund Of Clinical Trials Agreement		$ 1,600,000
National Cancer Institute [Member]
Research and Development Expense					$ 500,000
Moffitt License Agreement [Member]
Agreement Term					20 years
Cooperative Research and Development Agreement [Member]
Research and Development Expense					$ 2,000,000	2,000,000	1,800,000
PolyBioCept, AB - Exclusive and Co-Exclusive License Agreement [Member]
Research and Development Expense						200,000	2,700,000
Additional Milestone Payable	$ 8,700,000
Number Of Unregistered Common Stock To Be Issued	2,219,376
Reimbursement In Relation To Transfer Of Knowhow	$ 200,000
Clinical Trials Management Fees Payable	$ 100,000
Initial Term Of Licence Agreement	30 years
Payment For Upfront Exclusive License	$ 2,500,000
WuXi Apptech, Inc - Manufacturing and Services Agreement [Member]
Research and Development Expense					15,100,000	$ 13,900,000	$ 1,300,000
WuXi Apptech, Inc - Manufacturing and Services Agreement [Member] | Manufacturing Suites [Member]
Manufacturing and Services Agreement, Amount Payable				$ 2,500,000
WuXi Apptech, Inc - Manufacturing and Services Agreement [Member] | Commercial Manufacturing cGMP Suite [Member]
Manufacturing and Services Agreement, Amount Payable				$ 5,850,000
Moffitt License Agreement One [Member]
Payments For Upfront Licensing Fee					100,000
Moffitt License Agreement Two [Member]
Payments For Upfront Licensing Fee					100,000
Additional Milestone Payable					$ 400,000

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands	Dec. 31, 2018USD ($)
Total	$ 31,601
2,019	19,365
2,020	8,913
2,021	2,742
2,022	581
Therafter	0
Facility Leases [Member]
Total	3,014
2,019	1,373
2,020	1,223
2,021	418
2,022	0
Therafter	0
CMO Controctual Obligation [Member]
Total	28,587
2,019	17,992
2,020	7,690
2,021	2,324
2,022	581
Therafter	$ 0

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES (Details Textual)

Aug. 04, 2016USD ($)ft²

Nov. 02, 2018USD ($)

Oct. 19, 2018USD ($)

Apr. 20, 2018USD ($)

Jul. 31, 2017USD ($)

Apr. 28, 2017USD ($)ft²

Sep. 30, 2016USD ($)ft²

Dec. 31, 2018USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Jun. 05, 2017USD ($)

Apr. 30, 2015ft²

Dec. 31, 2014ft²

License And Commitments [Line Items]

Operating Leases, Rent Expense

$ 1,000,000

$ 1,000,000

$ 700,000

Lease Expiration Term

30 months

Operating Leases of Lessee, Contingent Rentals, Basis Spread on Variable Rate

3.00%

Operating Lease, Payments

$ 59,000

Tampa Lease [Member]

License And Commitments [Line Items]

Area of Land | ft²

8,673

6,043

5,115

Operating Leases, Rent Expense

$ 20,000

New York Lease [Member]

License And Commitments [Line Items]

Operating Leases, Rent Expense

$ 4,000

New York Lease [Member] | Office Space [Member]

License And Commitments [Line Items]

Operating Leases, Rent Expense

$ 7,000

Operating Leases, Future Minimum Payments Due

$ 9,000

Operating Leases, Rent Expense, Minimum Rentals

$ 18,000

San Carlos Lease [Member]

License And Commitments [Line Items]

Operating Leases, Rent Expense, Sublease Rentals

$ 26,000

San Carlos Lease [Member] | Land [Member]

License And Commitments [Line Items]

Area of Land | ft²

8,733

Lease Expiration Term

54 months

Operating Leases, Future Minimum Payments Due

$ 38,000

Teradata US, Inc [Member]

License And Commitments [Line Items]

Area of Land | ft²

11,449

LEGAL PROCEEDINGS (Details Text

LEGAL PROCEEDINGS (Details Textual)	Jun. 13, 2017USD ($)shares	Jun. 03, 2016USD ($)	Nov. 30, 2012USD ($)	Jun. 30, 2012USD ($)	Sep. 30, 2016shares	Dec. 31, 2018shares	Dec. 31, 2017shares	Dec. 31, 2016shares	Apr. 08, 2016USD ($)
Loss Contingency, Damages Sought, Value | $		$ 500,000
Common Stock Registered For Resale						128,500
Number of share options or share units exercised during the current period.						128,500
Twenty Eleven Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period						200,000
Dr. Steven Fischkoff [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	150,000
Severance Pay And Retention Bonus | $	$ 300,000
Warrant [Member]
Shares Sold Under Ineffective Registration					128,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross						0	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period						6,301,216	265,000	592,132
Minimum [Member]
Loss Contingency, Estimate of Possible Loss | $									$ 1,500,000
Solomon Capital, LLC [Member]
Proceeds from Related Party Debt | $			$ 100,000	$ 200,000
Debt Instrument, Convertible, Number of Equity Instruments						111,425
Solomon Capital, LLC [Member] | Commercial Paper [Member]
Debt Instrument, Face Amount | $									$ 200,000

QUARTERLY UNAUDITED RESULTS (De

QUARTERLY UNAUDITED RESULTS (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
Revenue	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Net loss attributable to common stockholders	$ (32,575)	$ (33,830)	$ (30,660)	$ (26,515)	$ (25,854)	$ (22,149)	$ (23,377)	$ (20,684)	$ (123,580)	$ (92,064)	$ (52,894)
Net loss per share, basic and diluted	$ (0.27)	$ (0.36)	$ (0.34)	$ (0.31)	$ (0.36)	$ (0.35)	$ (0.37)	$ (0.33)	$ (1.27)	$ (1.41)	$ (1.85)
Weighted average shares used in computing net loss per share, basic and diluted	119,085	95,077	90,236	84,350	72,794	63,332	62,457	62,286	97,277	65,242	55,268

RELATED PARTY TRANSACTIONS (Det

RELATED PARTY TRANSACTIONS (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	Sep. 14, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Payments for Legal Services		$ 500	$ 700	$ 800
Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award	The granted stock options vest in 12 quarterly installments (with 1/12th of the option shares having vested on the date of grant).
Share-based Compensation		20,027	11,968	$ 18,904
Consulting Agreement [Member]
Share-based Compensation		$ 700	$ 200
Board of Directors Chairman [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized	150,000
Share-based Compensation Arrangements by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price	$ 7.30