Iovance Biotherapeutics (IOVA) 10-Q 4 Nov 21 2021 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2021	Oct. 26, 2021
Document And Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2021
Entity File Number	001-36860
Entity Registrant Name	IOVANCE BIOTHERAPEUTICS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	75-3254381
Entity Address, Address Line One	999 Skyway Road, Suite 150
Entity Address, City or Town	San Carlos
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94070
City Area Code	650
Local Phone Number	260-7120
Title of 12(b) Security	Common stock, par value $0.000041666 per value
Trading Symbol	IOVA
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		156,899,118
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Entity Central Index Key	0001425205
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current Assets
Cash and cash equivalents	$ 58,590	$ 67,329
Short-term investments	517,859	562,108
Prepaid expenses and other assets	6,577	6,663
Total Current Assets	583,026	636,100
Property and equipment, net	88,034	59,159
Operating lease right-of-use assets	72,423	54,756
Long-term investments	78,247
Restricted cash	6,084	5,525
Long-term assets	1,011	12,918
Total Assets	828,825	768,458
Current Liabilities
Accounts payable	12,181	13,513
Accrued expenses	45,969	35,074
Operating lease liabilities - current	6,616	6,284
Total Current Liabilities	64,766	54,871
Non-Current Liabilities
Operating lease liabilities - noncurrent	64,729	45,375
Long-term note payable	1,000
Other liabilities		11,714
Total Non-Current Liabilities	65,729	57,089
Total Liabilities	130,495	111,960
Commitments and contingencies
Stockholders' Equity
Common stock, $0.000041666 par value; 300,000,000 shares authorized, 156,702,653 and 146,874,917 shares issued and outstanding as of September 30, 2021 and December 31, 2020, respectively	7	6
Accumulated other comprehensive income	(5)	19
Additional paid-in capital	1,771,440	1,486,662
Accumulated deficit	(1,073,115)	(830,193)
Total Stockholders' Equity	698,330	656,498
Total Liabilities and Stockholders' Equity	828,825	768,458
Series B Convertible Preferred Stock
Stockholders' Equity
Preferred stock, Value	$ 3	$ 4

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Common stock, par or stated value per share	$ 0.000041666	$ 0.000041666
Common stock, shares authorized	300,000,000	300,000,000
Common Stock, Shares, Issued	156,702,653	146,874,917
Common Stock, Shares, Outstanding	156,702,653	146,874,917
Series A Preferred Stock
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	194
Series B Convertible Preferred Stock
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	2,842,158	3,581,119
Preferred stock, shares outstanding	2,842,158	3,581,119

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Costs and expenses
Research and development expenses	$ 65,355	$ 43,050	$ 183,423	$ 149,276
General and administrative expenses	20,887	15,916	59,815	44,127
Total costs and expenses	86,242	58,966	243,238	193,403
Loss from operations	(86,242)	(58,966)	(243,238)	(193,403)
Other income
Interest income, net	120	395	316	2,219
Net Loss	$ (86,122)	$ (58,571)	$ (242,922)	$ (191,184)
Net Loss Per Share of Common Stock, Basic	$ (0.55)	$ (0.40)	$ (1.60)	$ (1.41)
Net Loss Per Share of Common Stock, Diluted	$ (0.55)	$ (0.40)	$ (1.60)	$ (1.41)
Weighted Average Shares of Common Stock Outstanding, Basic	155,508	146,492	152,221	135,457
Weighted Average Shares of Common Stock Outstanding, Diluted	155,508	146,492	152,221	135,457

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Condensed Consolidated Statements of Comprehensive Loss
Net Loss	$ (86,122)	$ (58,571)	$ (242,922)	$ (191,184)
Other comprehensive loss:
Unrealized loss on short-term investments	(38)	(162)	(24)	(65)
Comprehensive Loss	$ (86,160)	$ (58,733)	$ (242,946)	$ (191,249)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Series A Preferred StockPreferred Stock	Series B Convertible Preferred StockPreferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Comprehensive Income (Loss)	Accumulated Deficit	Total
Beginning Balance at Dec. 31, 2019		$ 4	$ 5	$ 869,354	$ 220	$ (570,612)	$ 298,971
Beginning Balance (in Shares) at Dec. 31, 2019	194	3,581,119	126,411,808
Stock-based compensation expense				30,655			30,655
Vesting of restricted shares issued for services (in shares)			13,449
Tax payments related to shares withheld for vested restricted stock units				(283)			(283)
Common stock issued upon exercise of stock options				6,704			6,704
Common stock issued upon exercise of stock options (in shares)			680,561
Common stock sold in public offering, net of offering costs			$ 1	567,042			567,043
Common stock sold in public offering, net of offering costs (in shares)			19,475,806
Unrealized loss on short-term investments					(65)		(65)
Net loss						(191,184)	(191,184)
Ending Balance at Sep. 30, 2020		$ 4	$ 6	1,473,472	155	(761,796)	711,841
Ending Balance (in Shares) at Sep. 30, 2020	194	3,581,119	146,581,624
Beginning Balance at Jun. 30, 2020		$ 4	$ 6	1,461,207	317	(703,225)	758,309
Beginning Balance (in Shares) at Jun. 30, 2020	194	3,581,119	146,434,810
Stock-based compensation expense				10,706			10,706
Common stock issued upon exercise of stock options				1,516			1,516
Common stock issued upon exercise of stock options (in shares)			146,814
Common stock sold in public offering, net of offering costs				43			43
Unrealized loss on short-term investments					(162)		(162)
Net loss						(58,571)	(58,571)
Ending Balance at Sep. 30, 2020		$ 4	$ 6	1,473,472	155	(761,796)	711,841
Ending Balance (in Shares) at Sep. 30, 2020	194	3,581,119	146,581,624
Beginning Balance at Dec. 31, 2020		$ 4	$ 6	1,486,662	19	(830,193)	656,498
Beginning Balance (in Shares) at Dec. 31, 2020	194	3,581,119	146,874,917
Stock-based compensation expense				50,661			50,661
Common stock issued upon purchase of employee stock purchase plan				970			970
Common stock issued upon purchase of employee stock purchase plan (in shares)			55,315
Common stock issued upon exercise of stock options				29,992			29,992
Common stock issued upon exercise of stock options (in shares)			2,559,361
Common stock sold in public offering, net of offering costs			$ 1	203,154			203,155
Common stock sold in public offering, net of offering costs (in shares)			6,474,099
Common stock issued from preferred stock conversion		$ (1)		1
Common stock issued from preferred stock conversion (in Shares)		(738,961)	738,961
Unrealized loss on short-term investments					(24)		(24)
Net loss						(242,922)	(242,922)
Ending Balance at Sep. 30, 2021		$ 3	$ 7	1,771,440	(5)	(1,073,115)	698,330
Ending Balance (in Shares) at Sep. 30, 2021	194	2,842,158	156,702,653
Beginning Balance at Jun. 30, 2021		$ 3	$ 7	1,731,363	33	(986,993)	744,413
Beginning Balance (in Shares) at Jun. 30, 2021	194	2,842,158	154,799,721
Stock-based compensation expense				19,306			19,306
Common stock issued upon exercise of stock options				20,771			20,771
Common stock issued upon exercise of stock options (in shares)			1,902,932
Unrealized loss on short-term investments					(38)		(38)
Net loss						(86,122)	(86,122)
Ending Balance at Sep. 30, 2021		$ 3	$ 7	$ 1,771,440	$ (5)	$ (1,073,115)	$ 698,330
Ending Balance (in Shares) at Sep. 30, 2021	194	2,842,158	156,702,653

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash Flows from Operating Activities
Net loss	$ (242,922)	$ (191,184)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	50,661	30,655
Non-cash lease expense	7,630	4,999
Accretion (amortization) of discounts and premiums on investments	5,177	359
Depreciation and amortization	1,766	819
Changes in assets and liabilities:
Prepaid expenses, other assets, and long-term assets	11,993	66
Right-of-use assets	(25,297)	(4,986)
Operating lease liabilities	19,686	(593)
Accounts payable	(740)	9,168
Accrued expenses and other liabilities	(2,046)	8,255
Net cash used in operating activities	(174,092)	(142,442)
Cash Flows from Investing Activities
Maturities of investments	544,454	358,493
Purchase of investments	(583,654)	(711,643)
Purchase of property and equipment	(30,006)	(23,456)
Net cash used in investing activities	(69,206)	(376,606)
Cash Flows from Financing Activities
Tax payments related to shares withheld for vested restricted stock units		(283)
Proceeds from the issuance of common stock upon exercise of options and employee stock purchase plan	30,962	6,704
Proceeds from the issuance of common stock, net	203,156	567,043
Proceeds from the issuance of debt	1,000
Net cash provided in financing activities	235,118	573,464
Net increase in cash, cash equivalents, and restricted cash	(8,180)	54,416
Cash, Cash Equivalents, and Restricted Cash, Beginning of Period	72,854	19,419
Cash, Cash Equivalents, and Restricted Cash, End of Period	64,674	73,835
Supplemental disclosure of non-cash investing and financing activities:
Net unrealized loss on short-term investments	(24)	(65)
Acquisitions of property and equipment included in accounts payable and accrued expense	(635)	(8,061)
Conversion of convertible preferred stock to common stock	(1)
Lease liabilities arising from obtaining right-of-use asset from new leases	17,275	4,667
Lease liabilities arising from obtaining right-of-use asset from lease modifications	$ 7,800	$ 22

GENERAL ORGANIZATION AND BUSINE

GENERAL ORGANIZATION AND BUSINESS	9 Months Ended
	Sep. 30, 2021
GENERAL ORGANIZATION AND BUSINESS
GENERAL ORGANIZATION AND BUSINESS	NOTE 1. GENERAL ORGANIZATION AND BUSINESS Iovance Biotherapeutics, Inc. (the “Company”, “we”, “us” or “our”) is a clinical-stage biopharmaceutical company focused on the development and commercialization of cell therapies as novel cancer immunotherapy products designed to harness the power of a patient’s own immune system to eradicate cancer cells. Tumor infiltrating lymphocyte (“TIL”) therapy is an autologous cell therapy platform technology that was originally developed by the National Cancer Institute (“NCI”), which conducted initial clinical trials in diseases such as metastatic melanoma and cervical cancer. The Company has developed a new, shorter manufacturing process for TIL therapy known as Generation 2 (“Gen 2”), which yields a cryopreserved TIL product. This proprietary and scalable manufacturing method is being further investigated in multiple indications. The Company’s lead product candidates include lifileucel for metastatic melanoma and metastatic cervical cancer. Lifileucel for metastatic cervical cancer was formerly known as LN-145. In addition to metastatic melanoma and metastatic cervical cancer, the Company is investigating the effectiveness and safety of TIL therapy and peripheral blood lymphocyte therapy for the treatment of squamous cell carcinoma of the head and neck, non-small cell lung cancer, and chronic lymphocytic leukemia through its sponsored trials, as well as in other oncology indications through collaborations. On June 1, 2017, the Company reincorporated from a Nevada corporation to a Delaware corporation. Basis of Presentation of Unaudited Condensed Consolidated Financial Information The accompanying unaudited condensed consolidated financial statements of the Company for the three and nine months ended September 30, 2021 and 2020 have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and pursuant to the requirements for reporting on Form 10-Q and Regulation S-X. Accordingly, they do not include all the information and footnotes required by GAAP for audited financial statements. However, such information reflects all adjustments (consisting solely of normal recurring adjustments), which are, in the opinion of management, necessary for the fair presentation of the Company's financial position and results of operations. Results shown for interim periods are not necessarily indicative of the results to be obtained for a full fiscal year. The balance sheet information as of December 31, 2020, was derived from the audited consolidated financial statements included in the Company's Annual Report on Form 10-K filed with the Securities and Exchange Commission (the “SEC”) on February 25, 2021. These interim financial statements should be read in conjunction with that report. 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 and does not anticipate that it will generate any significant 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 $242.9 million for the nine months ended September 30, 2021 and used $174.1 million of cash in its operating activities during the nine months ended September 30, 2021. For the nine months ended September 30, 2021, the Company received net proceeds of approximately $203.2 million from the “at the market” offering program the Company has in place with Jefferies LLC, acting as sales agent. As of September 30, 2021, the Company had $660.8 million in cash, cash equivalents, investments, and restricted cash ($58.6 million of cash and cash equivalents, $517.9 million in short-term investments, $78.2 million in long-term investments, and $6.1 million in restricted cash). The Company expects to continue its research and development activities, increase pre-commercial activities, and complete the construction of the tenant improvements for its Iovance Cell Therapy Center (the “ i CTC”) as well as the new headquarters’ office in San Carlos, California, all of which will increase the amount of cash used during the remainder of 2021 and beyond. Specifically, the Company expects continued spending on its current and planned clinical trials, continued expansion of manufacturing activities, higher payroll expenses as the Company increases its professional and scientific staff and continuation 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 and capital expenditures as planned for at least the next twelve months from the date these financial statements are issued. Impact of COVID-19 In December 2019, a novel coronavirus known as SARS-CoV-2 was first detected in Wuhan, Hubei Province, People’s Republic of China, causing outbreaks of the coronavirus disease, known as COVID-19, that has now spread globally. On January 30, 2020, the World Health Organization (“WHO”) declared COVID-19 a pandemic (the “COVID-19 Pandemic”). The Secretary of Health and Human Services declared a public health emergency on January 31, 2020, under section 319 of the Public Health Service Act (42 U.S.C. 247d), in response to the COVID-19 Pandemic. The full impact of the COVID-19 Pandemic is unknown and rapidly evolving. While the potential economic impact brought by and over the duration of the COVID-19 Pandemic may be difficult to assess or predict, the COVID-19 Pandemic has resulted in significant disruption of global financial markets, which could in the future negatively affect the Company's liquidity. In addition, a recession or market volatility resulting from the COVID-19 Pandemic could affect the Company’s business. Given the nature and type of the Company’s short-term investments in U.S. government securities, the Company does not believe the COVID-19 Pandemic has had or will have a material impact on the Company's current investment liquidity. Concentrations of Risk The Company is subject to credit risk from its portfolio of cash equivalents and 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, liquidity of investments sufficient to meet cash flow requirements of its business, and maximization of total return while maintaining safety and liquidity.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2021
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	NOTE 2. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Cash, Cash Equivalents, and 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 investments are classified as “available-for-sale” and are presented at fair value as either a current or non-current asset based on the length of maturity from the reporting date. Unrealized gains and losses on available-for-sale securities are included in accumulated other comprehensive income. Impairment losses related to credit losses (if any) are included in an allowance for credit losses with an offsetting entry to net loss. No impairment losses related to credit losses were recognized for the three and nine months ended September 30, 2021 and 2020. 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 Interest income, net in the Condensed Consolidated Statements of Operations. Gains and losses on securities sold are recorded based on the specific identification method and are included in Interest income, net in the Condensed Consolidated Statements 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 commercial papers, and places restrictions on maturities and concentration by type and issuer, except for securities issued by the U.S. government. Restricted Cash The Company maintains a required minimum balance, currently $6.1 million in a segregated bank account in connection with three letters of credit, one for $5.45 million for the benefit of the landlord for its commercial manufacturing facility used as a security deposit for the lease (See Note 10 - Leases), the second one for $74,685 for the benefit of a utilities service provider, and the third one for $559,082 for the benefit of the landlord for the Company’s new headquarters lease. The total amount is classified as Restricted Cash on the Condensed Consolidated Balance Sheet. The first letter of credit originally expired on May 28, 2020, however, it automatically extends for additional one-year periods, without written agreement, to May 28 in each succeeding calendar year, through at least 60 days after the lease expiration date. Further, on the expiration of the seventh year of the lease, and each anniversary date thereafter, the letter of credit may be decreased by $1.0 million, with a minimum security deposit of $1.45 million maintained through the end of the lease term. The second letter of credit of $74,685 expired on March 9, 2021, however, it automatically extends, without written agreement, to the expiration date of December 1, 2022. The third letter of credit of $559,082 expires on February 1, 2032, however, it will be automatically extended, without written agreement, for one-year periods to February in each succeeding calendar year. As of September 30, 2021, and December 31, 2020, restricted cash consisted of $6.1 million and $5.5 million, respectively. This amount has been classified as a non-current asset on the Company’s Condensed Consolidated Balance Sheets. The following table provides a reconciliation of cash, cash equivalents, and restricted cash, reported within the Condensed Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Condensed Consolidated Statements of Cash Flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, September 30, ​ ​ 2021 ​ 2020 ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 58,590 ​ $ 68,310 Restricted cash ​ 6,084 ​ 5,525 Total cash, cash equivalents and restricted cash ​ $ 64,674 ​ $ 73,835 ​ Loss per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock 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 shares of common stock issuable upon (i) the exercise of outstanding stock options and warrants, (ii) purchases though the 2020 Employee Stock Purchase Plan (the “2020 ESPP”), (iii) vesting of restricted stock units, and (iv) conversion of preferred stock, are only included in the calculation of diluted net loss per share when their effect is dilutive. As of September 30, 2021 and 2020, the following outstanding common stock equivalents have been excluded from the calculation of net loss per share because their impact would be anti-dilutive: ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ ​ 2021 2020 Stock options ​ 12,537,858 12,768,881 Series A Convertible Preferred Stock* ​ 97,000 97,000 Series B Convertible Preferred Stock* ​ 2,842,158 3,581,119 2020 ESPP ​ 36,263 ​ — Restricted stock units ​ 1,160,300 — ​ ​ 16,673,579 16,447,000 ​ * on an as-converted basis The effect of potentially dilutive securities would be reflected in diluted earnings per share of common stock 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 Accounting Standards Codification (“ASC”) 820, Fair Value Measurements and Disclosures 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–These are investments where values are based on unadjusted quoted prices for identical assets in an active market that the Company has the ability to access. Level 2–These are investments where values are based on quoted market prices in markets that are not active or model derived valuations in which all significant inputs are observable in active markets. Level 3–These are financial instruments where values are derived from techniques in which one or more significant inputs are unobservable. The Company’s financial instruments consist of cash, cash equivalents, short and long-term investments, and long-term notes payable, all of which are reported at their respective fair value on its Condensed Consolidated Balance Sheets. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s financial instruments consist of Level 1 and Level 2 assets. Where quoted prices are available in an active market, securities are classified as Level 1. When quoted market prices are not available for a specific security, the Company estimates the fair value by using quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs obtained from various third-party data providers, including but not limited to, benchmark yields, interest rate curves, reported trades, broker/dealer quotes, and market reference data. Level 2 assets consist of commercial paper and government agency securities. Level 2 inputs for the valuations are limited to quoted prices for similar assets or liabilities in active markets and inputs other than quoted prices that are observable for the asset. As of September 30, 2021 and December 31, 2020, the fair value of the Company’s financial assets, which consist of cash equivalents and short and long-term investments classified as available-for-sale securities, that were measured 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 September 30, 2021 ​ Level 1 Level 2 Level 3 Total U.S. treasury securities ​ $ 238,238 ​ $ — ​ $ — ​ $ 238,238 U.S. government agency securities ​ — ​ 12,233 ​ — ​ 12,233 Corporate securities ​ ​ — ​ ​ 43,308 ​ ​ — ​ ​ 43,308 Commercial paper ​ ​ — ​ ​ 312,325 ​ ​ — ​ ​ 312,325 Money market funds ​ ​ 32,577 ​ ​ — ​ ​ — ​ ​ 32,577 Total ​ $ 270,815 ​ $ 367,866 ​ $ — ​ $ 638,681 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Assets at Fair Value as of December 31, 2020 ​ Level 1 Level 2 Level 3 Total US treasury securities ​ $ 470,109 ​ $ — ​ $ — ​ $ 470,109 US government agency securities ​ 91,999 ​ — ​ — ​ 91,999 Money market funds ​ ​ 49,720 ​ ​ — ​ ​ — ​ ​ 49,720 Total ​ $ 611,828 ​ $ — ​ $ — ​ $ 611,828 ​ The available-for-sale securities in the Company’s Condensed Consolidated Balance Sheets are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 42,575 ​ $ 49,720 Short-term investments ​ ​ 517,859 ​ ​ 562,108 Long-term investments ​ ​ 78,247 ​ ​ — Cash equivalents and investments total ​ $ 638,681 ​ $ 611,828 ​ Use of Estimates The preparation of financial statements in conformity with 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 the assumptions made in valuing stock instruments issued for services and used in measuring operating right-of-use assets and operating lease liabilities, accounting for potential liabilities, capitalization of internal-use software development costs, and the valuation allowance associated with the Company’s deferred tax assets. Principles of Consolidation The accompanying consolidated financial statements include the accounts of Iovance Biotherapeutics, Inc. and its wholly-owned subsidiaries, Iovance Biotherapeutics Manufacturing LLC, Iovance Biotherapeutics GmbH, and Iovance Biotherapeutics B.V . All intercompany accounts and transactions have been eliminated. The U.S. dollar is the functional currency for all the Company's consolidated operations. Income Taxes On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) was enacted and signed into law, and GAAP requires recognition of the tax effects of new legislation during the reporting period that includes the enactment date. The CARES Act, among other things, includes changes to the tax provisions that benefits business entities and makes certain technical corrections to the 2017 Tax Cuts and Jobs Act. The tax relief measures for business entities include a five-year net operating loss carrybacks, suspension of annual deduction limitation of 80% taxable income from net operating losses generated in a tax year beginning after December 31, 2017, changes in the deductibility of interest, acceleration of alternative minimum tax credit refunds, payroll tax relief, and technical correction to allow accelerated deductions for qualified improvement property. The Company evaluated the impact of the CARES Act and determined the impact is immaterial for the three and nine months ended September 30, 2021. Leases The Company determines if an arrangement includes a lease at inception. Operating leases are included in its Condensed Consolidated Balance Sheet as Operating lease right-of-use assets and Operating lease liabilities as of September 30, 2021 and December 31, 2020. Operating lease right-of-use assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the net present value of lease payments, the Company uses an estimated incremental borrowing rate that is applicable to the Company based on the information available at the later of the lease commencement date or the date of adoption of Accounting Standard Update (“ASU”) No. 2016-02 and ASU No. 2018-10, Leases (together “Topic 842”). The operating lease right-of-use assets also include any lease payments made less lease incentives. The Company’s leases may include options to extend or terminate the lease, which is considered in the lease term when it is reasonably certain that the Company will exercise any such options. Lease expense is recognized on a straight-line basis over the expected lease term. The Company has elected not to apply the recognition requirements of Topic 842 for short-term leases. For lease agreements entered into after the adoption of Topic 842 that include lease and non-lease components, such components are generally accounted for separately. Stock-Based Compensation The Company periodically grants stock options to employees as compensation for services rendered. The Company accounts for all stock-based payment awards made to employees, including the employee stock purchase plans in accordance with the authoritative guidance provided by the Financial Accounting Standards Board (“FASB”) where the value of the award is measured on the date of grant and recognized over the vesting period. In accordance with ASU No. 2018-07, Compensation-Stock Compensation 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 term of the common stock options, and future dividends. The stock-based 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 issues restricted stock units (“RSUs”) and restricted stock awards (“RSAs”) from time to time as part of its share-based compensation programs. The Company measures the compensation cost with respect to RSUs and RSAs 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 awards. The fair value of RSUs and RSAs is based on the closing price of the Company’s common stock on the grant date. Accrued Research and Development Costs Research and development costs are expensed as incurred. Clinical development costs compose a significant component of research and development costs. The Company has a history of contracting with third parties that perform various clinical trial activities on its behalf. Service agreements with contract research organizations (“CROs”) and contract manufacturing organizations (“CMOs”) are recognized as the services are incurred. The Company accrues for expenses resulting from obligations under agreements with its third parties for which the timing of payments does not match the periods over which the materials or services are provided to the Company. Accruals are recorded based on estimates of services received and efforts expended pursuant to agreements established with CROs, CMOs and other outside service providers. These estimates are typically based on contracted amounts applied to the proportion of work performed and determined through analysis with internal personnel and external service providers as to the progress or stage of completion of the services. The Company makes judgements and estimates in determining the accrual balance in each reporting period. In the event advance payments are made to a CRO, CMO or other outside service provider, the payments are recorded within prepaid expenses and other current assets and subsequently recognized as research and development expense when the associated services have been performed. As actual costs become known, the Company adjusts its liabilities and assets. Inputs, such as the extent of services received and the duration of services to be performed, may vary from the Company’s estimates, which will result in adjustments to research and development expense in future periods. Changes in these estimates that result in material changes to the Company’s accruals could materially affect the Company’s results of operations. The Company’s historical estimates have not been materially different from actual amounts recorded. Preferred Stock The Company applies the accounting standards for distinguishing liabilities from equity when determining the classification and measurement of its preferred stock. Preferred stock subject to mandatory redemption are classified as liability instruments and are measured at fair value. Conditionally redeemable preferred stock (including preferred stock 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 stock is classified as stockholders’ equity. Recent Accounting Standards Adopted In December 2019, the FASB issued ASU No. 2019-12, Income Taxes Simplifying the Accounting for Income Taxes,

CASH EQUIVALENTS AND INVESTMENT

CASH EQUIVALENTS AND INVESTMENTS	9 Months Ended
	Sep. 30, 2021
CASH EQUIVALENTS AND INVESTMENTS
CASH EQUIVALENTS AND INVESTMENTS	NOTE 3. CASH EQUIVALENTS AND INVESTMENTS Cash equivalents consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 42,575 ​ $ 49,720 Cash equivalents total ​ $ 42,575 ​ $ 49,720 ​ Cash equivalents in the tables above exclude cash demand deposits of $16.0 million and $17.6 million as of September 30, 2021 and December 31, 2020, respectively. ​ The following table summarizes the Company’s investments that are classified as available-for-sale debt securities (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 ​ ​ ​ ​ ​ ​ ​ Short-term investments ​ $ 517,859 ​ $ 562,108 Long-term investments ​ ​ 78,247 ​ ​ — Total investments ​ $ 596,106 ​ $ 562,108 ​ The following table summarizes the classification of the Company’s available-for-sale debt securities in its Condensed Consolidated Balance Sheets (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, Investments ​ 2021 2020 U.S. treasury securities ​ $ 238,238 ​ $ 470,109 U.S. government agency securities ​ 12,233 ​ 91,999 Corporate securities ​ ​ 43,308 ​ ​ — Commercial paper ​ 302,327 ​ — Total investments ​ $ 596,106 ​ $ 562,108 ​ The cost and fair value of investments as of September 30, 2021 and December 31, 2020 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ ​ ​ As of September 30, 2021 Cost Gains Losses Fair Value U.S. treasury securities ​ $ 238,252 ​ $ 17 ​ $ (31) ​ $ 238,238 U.S. government agency securities ​ 12,233 ​ — ​ — ​ 12,233 Corporate securities ​ ​ 43,325 ​ ​ — ​ ​ (17) ​ ​ 43,308 Commercial papers ​ ​ 302,303 ​ ​ 37 ​ ​ (13) ​ ​ 302,327 Total investments ​ $ 596,113 ​ $ 54 ​ $ (61) ​ $ 596,106 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ ​ ​ As of December 31, 2020 Cost Gains Losses Fair Value U.S. treasury securities ​ $ 470,108 ​ $ 30 ​ $ (29) ​ $ 470,109 U.S. government agency securities ​ 91,981 ​ 20 ​ (2) ​ 91,999 Total investments ​ $ 562,089 ​ $ 50 ​ $ (31) ​ $ 562,108 ​ The following table summarizes the Company’s available-for-sale debt securities by contractual maturity (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 ​ ​ Amortized Cost Fair Value ​ ​ ​ ​ ​ ​ ​ Within one year ​ $ 517,835 ​ $ 517,859 One year to two years ​ ​ 78,278 ​ ​ 78,247 Total investments ​ $ 596,113 ​ $ 596,106 ​ All available-for-sale securities held as of September 30, 2021 and December 31, 2020 had contractual maturities of less than two years. No significant available-for-sale securities held as of the periods presented have been in a continuous unrealized loss position for more than 12 months. As of September 30, 2021, unrealized losses on available-for-sale investments are not attributed to credit risk. The Company determined that it has the ability and intent to hold all marketable securities that have been in a continuous loss position until maturity or recovery. To date, the Company has not recorded any impairment charges on its marketable securities.

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	9 Months Ended
	Sep. 30, 2021
PROPERTY AND EQUIPMENT
PROPERTY AND EQUIPMENT	NOTE 4. PROPERTY AND EQUIPMENT Property and equipment, net consists of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2021 2020 Lab equipment ​ $ 12,051 ​ $ 4,656 Leasehold improvements ​ 57,817 ​ 2,573 Computer equipment ​ 1,163 ​ 270 Computer software ​ ​ 674 ​ ​ — Office furniture and equipment ​ 1,244 ​ 480 Machinery and equipment ​ ​ 82 ​ ​ — Construction in progress ​ 22,347 ​ 56,758 Total property and equipment, cost ​ 95,378 ​ 64,737 Less: Accumulated depreciation and amortization ​ (7,344) ​ (5,578) Property and equipment, net ​ $ 88,034 ​ $ 59,159 ​ Depreciation expense for the three months ended September 30, 2021 and 2020, was $1.0 million and $0.3 million, respectively. Depreciation expense for the nine months ended September 30, 2021 and 2020 was $1.8 million and $0.8 million, respectively. During the three months ended September 30, 2021, the Company placed $62.3 million of assets related to the i million.

ACCRUED EXPENSES

ACCRUED EXPENSES	9 Months Ended
	Sep. 30, 2021
ACCRUED EXPENSES
ACCRUED EXPENSES	NOTE 5. ACCRUED EXPENSES Accrued expenses consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 ​ ​ ​ ​ ​ ​ ​ Clinical related ​ $ 12,577 ​ $ 15,661 Accrued payroll and employee related expenses ​ ​ 15,167 ​ ​ 9,032 R&D manufacturing related ​ 9,108 ​ 3,266 Facilities related ​ ​ 5,082 ​ ​ 4,342 Legal and related services ​ 1,671 ​ 1,061 Accrued other ​ 2,364 ​ 1,712 Total accrued expenses ​ $ 45,969 ​ $ 35,074 ​

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	9 Months Ended
	Sep. 30, 2021
STOCKHOLDERS' EQUITY
STOCKHOLDERS' EQUITY	NOTE 6. STOCKHOLDERS’ EQUITY Common Stock The Company’s certificate of incorporation, as amended, authorizes the issuance of up to 300,000,000 shares of the Company’s common stock, par value $0.000041666. As of September 30, 2021, 156,702,653 shares of the Company’s common stock were issued and outstanding . Public Offerings In June 2020, the Company closed an underwritten public offering of 16,935,484 shares of the Company’s common stock at a public offering price of $31.00 per share, before underwriting discounts, which included 2,540,322 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 "June 2020 Public Offering"). The gross proceeds from the offering, before deducting the underwriting discounts and commissions and other offering expenses payable by the Company, were $603.7 million, with net proceeds to the Company of $567.0 million. Preferred Stock The Company’s certificate of incorporation authorizes the issuance of up to 50,000,000 shares of “blank check” preferred stock. As of September 30, 2021, 17,000 shares were designated as Series A Convertible Preferred Stock (“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. Each share of Series A Preferred Stock is initially convertible into 500 shares of common stock. 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. No shares of Series A Convertible Preferred Stock were converted during the nine months ended September 30, 2021 or 2020. As of September 30, 2021, and December 31, 2020, 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. Each share of Series B Preferred Stock is initially convertible into 1 share of common stock. The Series B 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 B 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. 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 nine months ended September 30, 2021, a total of 738,961 of Series B Convertible Preferred Stock were converted into 738,961 shares of common stock. No shares of Series B Convertible Preferred Stock were converted during the nine months ended September 30, 2020. As of September 30, 2021, and December 31, 2020, 2,842,158 and 3,581,119 shares of Series B Preferred Stock (that are convertible into 2,842,158 and 3,581,119 shares of common stock) remained outstanding, respectively. At the Market Offering Program On February 8, 2021, the Company entered into an Open Market Sale Agreement (the “Sales Agreement”) with Jefferies LLC (“Jefferies”) with respect to an “at the market” offering program, under which the Company may, from time to time, in its sole discretion, issue and sell through Jefferies, acting as sales agent, up to $350.0 million of shares of the Company’s common stock (the “Common Shares”). The issuance and sale, if any, of the Common Shares by the Company under the Sales Agreement will be made pursuant to a prospectus supplement, dated February 8, 2021, to the Company’s Registration Statement on Form S-3ASR, which became effective immediately upon filing with the Securities and Exchange Commission on May 27, 2020. Pursuant to the Sales Agreement, Jefferies may sell the Common Shares by any method permitted by law deemed to be an “at the market” offering as defined in Rule 415 of the Securities Act of 1933, as amended. Jefferies will use commercially reasonable efforts consistent with its normal trading and sales practices to sell the Common Shares from time to time, based upon instructions from the Company (including any price or size limits or other customary parameters or conditions the Company may impose). The Company will pay Jefferies a commission of up to 3.0% of the gross sales proceeds of any Common Shares sold through Jefferies under the Sales Agreement. The Company is not obligated to make any sales of Common Shares under the Sales Agreement. The offering of Common Shares pursuant to the Sales Agreement will terminate upon the earlier to occur of (i) the issuance and sale, through Jefferies, of all Common Shares subject to the Sales Agreement and (ii) termination of the Sales Agreement in accordance with its terms. For the nine months ended September 30, 2021, the Company received approximately $203.2 million in net proceeds, net of offering costs, through the sale of 6,474,099 shares of its common stock through the Sales Agreement at a weighted average price per share of $32.12, respectively. No sales were made pursuant to the Sales Agreement during the three months ended September 30, 2021.

STOCK BASED COMPENSATION

STOCK BASED COMPENSATION	9 Months Ended
	Sep. 30, 2021
STOCK BASED COMPENSATION
STOCK BASED COMPENSATION	NOTE 7. STOCK BASED COMPENSATION Equity Incentive Plans On October 14, 2011, the Company’s Board of Directors (the “Board”) 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 Board 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 Board 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 September 30, 2021, 11,240 shares were available for future grant under the 2011 Plan. Per the terms of the 2011 Plan, no equity awards may be granted under the 2011 Plan after the ten-year anniversary of the plan’s adoption by the Board. On September 19, 2014, 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. As of September 30, 2021, 80,551 shares were available for grant under the 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. On June 8, 2020, the Company's stockholders approved an amendment to the 2018 Plan to increase the number of shares available for issuance upon the exercise of stock options under the 2018 Plan from 6,000,000 to 14,000,000 shares, which became effective immediately. As of September 30, 2021, 3,792,680 shares of common stock were available for grant under the 2018 Plan. On September 22, 2021, the Board adopted the Iovance Biotherapeutics, Inc. 2021 Inducement Plan (the “2021 Inducement Plan”). The 2021 Inducement Plan provides for the grant of 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. The 2021 Inducement Plan was recommended for approval by the Compensation Committee of the Board (the “Compensation Committee”), and subsequently approved and adopted by the Board without stockholder approval pursuant to Rule 5635(c)(4) of the Nasdaq listing rules. The Board has reserved 1,000,000 shares of the Company’s common stock for issuance pursuant to equity awards granted under the 2021 Inducement Plan, and the 2021 Inducement Plan will be administered by the Compensation Committee. In accordance with Rule 5635(c)(4) of the Nasdaq listing rules, equity awards under the 2021 Inducement Plan may only be made to an employee if such employee is granted such equity awards in connection with his or her commencement of employment with the Company or a subsidiary and such grant is an inducement material to his or her entering into employment with the Company or such subsidiary. In addition, awards under the 2021 Inducement Plan may only be made to employees who have not previously been an employee or member of the Board (or any parent or subsidiary of the Company) or following a bona fide period of non-employment of the employee by the Company (or a parent or subsidiary of the Company). As of September 30, 2021, 1,000,000 shares of common stock were available for grant under the Inducement Plan. Stock Options A summary of the stock option activity during the nine months ended September 30, 2021, is presented in the following table: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Weighted ​ Average ​ Aggregate ​ ​ Number ​ Average ​ Remaining ​ Intrinsic ​ ​ of ​ Exercise ​ Contract ​ Value ​ Options ​ Price Life (in thousands) Outstanding as of December 31, 2020 ​ 12,615,638 ​ $ 18.08 ​ ​ ​ ​ ​ Granted ​ 5,023,599 ​ 39.82 ​ ​ ​ Exercised ​ (2,559,361) ​ 11.72 ​ ​ ​ Expired/Forfeited ​ (2,542,018) ​ 32.20 ​ ​ ​ Outstanding and vested as of September 30, 2021 ​ 12,537,858 ​ $ 25.22 ​ 7.70 ​ $ 65,954 ​ ​ ​ ​ ​ ​ ​ ​ Options exercisable as of September 30, 2021 ​ 6,233,363 ​ $ 15.74 ​ 6.34 ​ $ 60,233 ​ The aggregate intrinsic value in the table above reflects the total pre-tax intrinsic value (calculated as the difference between the Company’s closing stock price on the last trading day of the quarter ended September 30, 2021 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 September 30, 2021. The intrinsic value of the Company’s stock options changes based on the closing price of the Company’s common stock. Employee Stock Purchase Plan In June 2020, the Company adopted the 2020 ESPP upon its approval by the Company’s shareholders at its Annual Stockholders Meeting on June 8, 2020. The Company reserved 500,000 shares of its common stock for issuance under the 2020 ESPP. Under the 2020 ESPP, employees of the Company can purchase shares of its common stock based on a percentage of their compensation subject to certain limits. The purchase price per share is equal to the lower of 85% of the fair market value of its common stock on the offering date or the purchase date with a six month look-back feature. The 2020 ESPP purchases are settled with common stock from the 2020 ESPP’s previously authorized and available pool of shares. The compensation expenses related to the 2020 ESPP for the three and nine months ended September 30, 2021 were $0.2 million and $1.0 million, respectively. No compensation expenses related to the 2020 ESPP were recognized for the same periods in 2020. As of September 30, 2021, 55,315 shares were issued under the 2020 ESPP and there was $0.1 million of unrecognized compensation cost associated with the 2020 ESPP, which will be recognized over the remaining 2.3 months. Restricted Stock Units On June 1, 2016, the Company entered into an RSU agreement with the Company’s former Chief Executive Officer, Maria Fardis, Ph.D., M.B.A., pursuant to which the Company granted Dr. Fardis 550,000 non-transferrable RSUs at a fair market value price of $5.87 per share as an inducement to her employment pursuant to the exception to The Nasdaq Global Market rules that generally require stockholder approval of equity incentive plans. The 550,000 RSUs vested 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 vested upon the satisfaction of certain clinical trial milestones; and (iii) 137,500 restricted stock units vested in equal monthly installments over the 36-month period following the first anniversary of the effective date of Dr. Fardis’ employment. These RSUs were fully vested as of June 1, 2020 and no RSUs associated with this agreement were outstanding as of September 30, 2021 or December 31, 2020. In June 2021, under the terms of the 2018 Plan, the Company granted 1,253,540 RSUs to its executives and employees. The awards are time-based, and each award has one of two vesting conditions. For some RSU awards, 100% of the RSUs will vest on the first anniversary of the grant date, and for others, 50% of the RSUs will vest on the first anniversary of the grant date with the remaining 50% vesting on December 31, 2022, assuming all time-based conditions are achieved. A summary of the RSU activity during the nine months ended September 30, 2021 is presented in the following table: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ Number ​ Average ​ ​ ​ of ​ Grant Date ​ ​ RSUs Fair Value ​ Outstanding, non-vested as of December 31, 2020 ​ — ​ $ — ​ Granted ​ 1,253,540 ​ ​ 23.87 ​ Vested ​ — ​ ​ — ​ Canceled/Forfeited ​ (93,240) ​ ​ 23.87 ​ Outstanding, non-vested as of September 30, 2021 ​ 1,160,300 ​ $ 23.87 ​ ​ ​ ​ ​ ​ ​ ​ ​ As of September 30, 2021, there was $20.8 million of related unrecognized compensation cost associated with RSUs, which the Company expects to recognize over a remaining weighted-average period of 0.88 years. The aggregate intrinsic value of the nonvested RSUs outstanding as of September 30, 2021 was $28.6 million. Stock-Based Compensation Total stock-based compensation expenses related to all of the Company’s stock-based awards were recorded on the Statements of Operations as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2021 2020 2021 2020 ​ Research and development ​ $ 11,504 ​ $ 5,282 ​ $ 29,291 ​ $ 15,065 ​ General and administrative ​ 7,802 ​ 5,424 ​ 21,370 ​ 15,590 ​ Total stock-based compensation expenses ​ $ 19,306 ​ $ 10,706 ​ $ 50,661 ​ $ 30,655 ​ ​ Total stock-based compensation expense by type of award was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2021 2020 ​ 2021 2020 ​ Stock option expenses ​ $ 13,339 ​ $ 10,706 ​ $ 42,782 ​ $ 30,543 ​ Restricted stock unit expenses ​ 5,788 ​ — ​ 6,887 ​ 112 ​ 2020 ESPP expenses ​ 179 ​ — ​ 992 ​ — ​ Total stock-based compensation expenses ​ $ 19,306 ​ $ 10,706 ​ $ 50,661 ​ $ 30,655 ​ ​ As of September 30, 2021, there was $105.1 million of total unrecognized compensation expense related to the options to be recognized over a weighted average period of 1.93 years. The weighted average grant date fair value for employee options granted under the Company’s stock option plans during the nine months ended September 30, 2021 and 2020 was $23.29 and $16.37 per option, respectively.

LICENSES AND AGREEMENTS

LICENSES AND AGREEMENTS	9 Months Ended
	Sep. 30, 2021
LICENSES AND AGREEMENTS
LICENSES AND AGREEMENTS	NOTE 8. LICENSES AND AGREEMENTS National Institutes of Health (the “NIH”) and the National Cancer Institute (the “NCI”) Cooperative Research and Development Agreement (the “CRADA”) In August 2011, the Company signed the CRADA for a five-year term with the NCI to work with Dr. Steven Rosenberg on developing TIL therapies that are designed to destroy metastatic melanoma cells. In January 2015, the Company executed an 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 cancers associated with Human Papilloma Virus (“HPV”). In August 2016, the NCI and the Company entered into 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 products licensed by the U.S. Food and Drug Administration (the “FDA”) and commercially available reagents routinely used for adoptive cell therapy. The parties have continued 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. In August 2021, the NCI and the Company entered into a third amendment to the CRADA. The third amendment, among other things, extended the term of the CRADA by three years to August 2024. 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, 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 and suitable for use in clinical trials, where the Company holds the investigational new drug application for such clinical trial. The extended CRADA has a three-year term expiring in August 2024. 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 $0.5 million for the three months ended September 30, 2021 and 2020, and $1.5 million for the nine months ended September 30, 2021 and 2020 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 “Patent License Agreement”) with the NIH, an agency of the U.S. Public Health Service within the Department of Health and Human Services, 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 TIL adoptive cell therapy products for the treatment of metastatic melanoma, lung, breast, bladder, and HPV-positive cancers (the “Indications”). The Patent License Agreement required 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 Indications and other direct costs incurred by the NIH pursuant to the agreement. Effective May 6, 2021, the Company entered into an Amended and Restated Patent License Agreement with NIH (the “Amended and Restated Patent License Agreement”), which includes the grant of additional exclusive, worldwide patent rights in the Indications to cytokine-tethered TIL technology, and expands the non-exclusive, worldwide field of use to all cancers. The Amended and Restated Patent License Agreement requires the Company to pay royalties based on a percentage of net sales in jurisdictions where patent rights exist, which percentage can fall into a tier that may be less than one percent to mid-single digits depending upon certain events, including the exclusivity of the rights, and a percentage of revenues from sublicensing arrangements, and the Company expects lower overall royalty payments as a result. The Company also agreed to potential milestone payments on the achievement of certain clinical, regulatory, and commercial sales milestones for each of the Indications and other direct costs incurred by the NIH pursuant to the Amended and Restated Patent License Agreement. The Company anticipates making a milestone payment in the low single-digit millions of dollars in conjunction with the approval of a Biologics License Application for any of its product candidates covered by the Amended and Restated Patent License Agreement. The term of the Amended and Restated Patent License Agreement continues until the expiry of the last-to-expire patent rights licensed thereunder, and the agreement contains standard termination provisions. 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 U.S., 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 three-year Sponsored Research Agreement with H. Lee Moffitt Cancer Center (“Moffitt”) which expired in December 2019. In June 2020, the Company entered into a new Sponsored Research Agreement with Moffitt, with a term that ends either upon completion of the research thereunder or on July 1, 2022, whichever is sooner, and under which immaterial payments will be made to Moffitt in connection with the research services thereunder. 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. The Company recorded a de minimis amount and $0.1 million of research and development costs of for the three months ended September 30, 2021 and 2020 respectively, and $0.3 million for the nine months ended September 30, 2021 and $0.5 million for the nine months ended September 30, 2020, 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 U.S., Europe, and Japan and in other countries designated by the Company in agreement with Moffitt. No expenses were recorded for the First Moffitt License for the three and nine months ended September 30, 2021 and 2020. The Company entered into a license agreement with Moffitt effective as of May 7, 2018 (the “Second Moffitt License”), under which the Company received an exclusive 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 in 2018. An annual license maintenance fee is 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. The Company subsequently exercised its option to exclusively license Moffitt’s rights to patent pending technologies related to the use of tumor digests in conjunction with TIL manufacturing processes and therapies, and the Company and Moffitt amended and restated the Second Moffitt License in October 2021 (the “Amended & Restated Second Moffitt License”) to include these rights. Pursuant to the Amended & Restated Second Moffitt License, the Company is obligated to pay an upfront licensing fee in the amount of $0.2 million in 2021. In addition, the Company agreed to pay an annual commercial use payment for each indication for which a first sale has occurred for products relating to the use of 4-1BB agonists and for products relating to the use of tumor digests. The Company recorded a de minimis amount for the three months ended September 30, 2021 and 2020, respectively, and a de minimis amount for the nine months ended September 30, 2021 and 2020, respectively, as research and development expenses in connection with the Second Moffit License. M.D. Anderson Cancer Center Strategic Alliance Agreement On April 17, 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 acquired 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. The Company recorded $0.1 million and $0.3 million expenses associated with the MDACC SAA for the three months ended September 30, 2021 and 2020, respectively, and $0.2 million and $0.5 million for the nine months ended September 30, 2021 and 2020, respectively, as research and development expenses. WuXi Apptec, Inc. In November 2016, the Company entered into a three-year manufacturing and services agreement (“MSA”) with WuXi AppTec, Inc. (“WuXi”) pursuant to which WuXi agreed to provide manufacturing and other services, which has since been amended and assigned to its subsidiary Iovance Biotherapeutics Manufacturing LLC. 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, both suites are expected to be capable of being used for the commercial manufacture of its products. The statements of work for the first suite were amended in 2019, September 2020 and February 2021, and the statement of work for the second suite was amended in 2019. The statements of work for the facility include a fixed component to reserve a dedicated suite and a trained work force, and a variable component, mainly materials and testing used during the manufacturing processes. Both statements of work provide for adjustments to the targeted production capacity levels and the corresponding fixed fees upon written notice from the Company of 30 days and 90 days for the first and second suites, respectively. The terms of the related statements of work for the first suite currently extends to February 2022 and the terms of the second manufacturing suite were extended to December 2022. The Company recorded costs associated with agreements with WuXi of $4.5 million and $2.8 million for the three months ended September 30, 2021 and 2020, respectively, and $12.7 million and $16.2 million for the nine months ended September 30, 2021 and 2020, respectively, as research and development expenses. Cellectis S.A. On January 12, 2020, the Company entered into a research collaboration and exclusive worldwide license agreement whereby the Company will license gene-editing technology from Cellectis S.A. ("Cellectis"), a clinical-stage biopharmaceutical company, to develop TIL therapies that have been genetically edited. Financial terms of the license include development, regulatory and sales milestone payments from the Company to Cellectis, as well as royalty payments based on net sales of TALEN-modified TIL products. The Company recorded costs associated with agreements with Cellectis of $0.1 million for the three months ended September 30, 2021 and 2020 and $0.3 million for the nine months ended September 30, 2021 and 2020, respectively, as research and development expenses. Novartis Pharma AG On January 12, 2020, the Company obtained a license from Novartis Pharma AG (“Novartis”) to develop and commercialize an antibody cytokine engrafted protein, which the Company refers to as IOV-3001. Under the agreement, the Company has paid an upfront payment to Novartis and may pay future milestones related to initiation of patient dosing in various phases of clinical development for IOV-3001 and approval of the product in the U.S, EU, and Japan. Novartis is also entitled to low-to-mid single digit percentage royalties from commercial sales of the product. No expenses were recorded for the three and nine months ended September 30, 2021. The Company recorded costs associated with the license agreement from Novartis of $10.0 million as research and development expenses for the nine months ended September 30, 2020.

LEGAL PROCEEDINGS

LEGAL PROCEEDINGS	9 Months Ended
	Sep. 30, 2021
LEGAL PROCEEDINGS
LEGAL PROCEEDINGS	NOTE 9. LEGAL PROCEEDINGS Derivative Lawsuit. its current directors, as defendants, in the Court of Chancery in the State of Delaware. The complaint alleges breach of fiduciary duty and a claim for unjust enrichment in connection with alleged excessive compensation of certain non-executive directors of the Company . The defendants intend 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 these matters. Solomon Capital, LLC. Solomon Capital, LLC, Solomon Capital 401(K) Trust, Solomon Sharbat and Shelhav Raff v. Lion Biotechnologies, Inc. 1-for-100 right to convert their advances and payments into shares of the Company's common stock in the restructuring that took effect in May 2013. Based on the foregoing, the Solomon Plaintiffs allege causes for breach of contract and unjust enrichment and demand judgment against the Company in an unspecified amount exceeding $1.5 million, plus interest. On June 3, 2016, the Company filed an answer and counterclaims in the lawsuits. The Company has asserted counterclaims for fraudulent inducement, fraudulent misrepresentation, fraudulent concealment, breach of fiduciary duty, and breach of contract, alleging principally that the counterclaim defendants misrepresented their qualifications and failed to disclose that Solomon Sharbat was the subject of an investigation by the Financial Industry Regulatory Authority (“FINRA”) that resulted in the loss of his FINRA license. In its counterclaims, the Company is seeking damages in an amount exceeding $0.5 million and an order rescinding any and all agreements that the Solomon Plaintiffs contend entitled them to obtain shares of Company stock. On May 12, 2020, the court granted the Company’s motion for summary judgment limiting the Solomon Plaintiffs’ damages for the Equity Claim to $47,420. The Solomon Plaintiffs filed a notice of appeal of this summary judgment on June 9, 2020. On July 2, 2020, the court granted the Company’s motion to dismiss the First Solomon Suit for want of prosecution. On January 4, 2021, the court granted the Solomon Plaintiffs motion for reconsideration, and reinstituted the case. On January 15, 2021, the Company filed a notice of appeal of the court’s grant of the Solomon Plaintiffs motion for reconsideration. On May 11, 2021, the Appellate Division upheld the court’s grant of the Solomon Plaintiffs’ motion for reconsideration of the dismissal of the First Solomon Suit for want of prosecution. On September 27, 2019, the Solomon Plaintiffs filed a new lawsuit (through new legal counsel) (“the Second Solomon Suit”) titled Solomon Capital, LLC, Solomon Capital 401(K) Trust, Solomon Sharbat and Shelhav Raff v. Iovance Biotherapeutics, Inc., f/k/a/ Lion Biotechnologies Inc. f/k/a/ Genesis Biopharma Inc., and Manish Singh The Company intends to vigorously defend these complaints and pursue its counterclaims, as applicable. At the current stage of the litigation, in both the First Solomon Suit and the Second Solomon Suit, 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. The Company may be involved, from time to time, in legal proceedings and claims arising in the ordinary course of its 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 its financial position, results of operations or cash flows.

LEASES

LEASES	9 Months Ended
	Sep. 30, 2021
LEASES
LEASES	NOTE 10. LEASES Facilities Leases The Company has evaluated the following existing facility leases and determined that, effective upon the adoption of Topic 842, they were all operating leases. Operating lease right-of-use assets and liabilities were recognized as of January 1, 2019 based on the present value of the remaining lease payments over the lease term. As the Company’s leases do not provide an implicit rate, the Company utilized a third party in determining an incremental borrowing rate based on the information available as of the adoption date of Topic 842 to obtain the present value of lease payments. The Company’s lease terms may include options to extend or terminate the lease which are included in the lease term when it is reasonably certain that it will exercise any such options. Lease expense is recognized on a straight-line basis over the expected lease term. The Company elected not to apply the recognition requirements of Topic 842 for short-term leases that have a lease term of 12 months or less. New Headquarters Lease On February 8, 2021, the Company entered into a lease agreement with ARE-San Francisco No. 63, LLC (the “New Headquarters Lease”) for laboratories and offices to be constructed in Suite 400 of an existing building located at 825 Industrial Road, San Carlos, California (the “Building”), commonly known as The District. Under the New Headquarters Lease, the Company will lease approximately 49,918 rentable square feet of space in the Building (the “ Headquarters Premises”). The New Headquarters Lease is for a term of 120 months , commencing upon the first day of the first full month (the “Rent Commencement Date”) after the earlier to occur of (i) the date that is 12 months and one day after the execution date of the New Headquarters Lease (the “Commencement Date”), which is February 9, 2022, or (ii) the date that the Tenant Improvements (as defined therein) are substantially completed, which is currently expected to be at the end of 2021; provided, however, that the Rent Commencement Date shall be delayed 1 day for each day after the Commencement Date that (a) to the extent that, after the Commencement Date, any governmental authority having jurisdiction, as a result of the COVID-19 outbreak in the United States, declares or implements any order or mandate that restricts construction activities in San Mateo County, California (any such order or mandate, a “Government Mandate”), to the extent that such Government Mandate precludes the construction of tenant improvements, or (b) a landlord delay occurs. The New Headquarters Lease includes an option to extend the term of the lease for 60 months , exercisable under certain conditions and at a market rate as described in the New Headquarters Lease. Commencing 210 days after the Rent Commencement Date as the result of a rent abatement, the Company’s monthly base rent under the New Headquarters Lease will be approximately $280,000 , subject to an annual increase of 3% . Beginning in 2022, the Company will also be responsible for paying operating expenses. The 120-month five years San Carlos Existing Headquarters Leases On August 4, 2016, the Company entered into an agreement with Hudson Skyway Landing, LLC (the “Suite 150 Lease”) to lease 8,733 square feet of space for its corporate headquarters on the first floor of the building located at 999 Skyway Road, San Carlos, California commonly known as Skyway Landing II. The term of the Lease was 54 months beginning on the commencement date and expired in April 2021. Monthly lease payments were approximately $38,000. On October 19, 2018, the Company entered into an agreement (the “Lease”) to lease 12,322 square feet of office space located adjacent to the Company’s headquarters in San Carlos, California. The term of the lease expired on April 30, 2021. Monthly lease payments were approximately $59,000, subject to an annual increase of 3%. On June 19, 2019, the Company entered into a first amendment (the “Amended Lease”) to the Lease for additional space at its corporate headquarters in San Carlos, California. Under the Amended Lease, the Company leased an additional 8,110 square feet (the “Expansion Space”), for a total of approximately 20,432 square feet of space on the first floor of Skyway Landing II. The term of the Amended Lease expired on April 30, 2021. Monthly lease payments were approximately $39,000 for the first year and $40,000 for the second year. On February 8, 2021, the Company entered into two amendments (the “Suite 100 and 125 Second Amendment” and the “Suite 150 First Amendment”) to the Amended Lease and the Suite 150 Lease, respectively. Under the Suite 100 and Suite 125 Second Amendment, the Company extended the Amended Lease which expired on April 30, 2021, to December 31, 2021. The Company’s monthly base rent under the Suite 100 and Suite 125 Second Amendment will be approximately $103,000. The Company is also responsible for paying its portion of operating expenses and real estate taxes. The Company has an option to extend the expiration of the Suite 100 and Suite 125 Second Amendment for one month or nine months, at its discretion, by providing notice as specified in the Suite 100 and Suite 125 Second Amendment. On September 1, 2021, the Company entered into an agreement to extend the lease term to January 31, 2022 for approximately $106,300 a month. Under the Suite 150 First Amendment, the Company extended the Suite 150 Lease, which also expired on April 30, 2021, to December 31, 2021. The Company’s monthly base rent under the Suite 150 First Amendment is approximately $44,000. The Company is also responsible for paying its portion of operating expenses and real estate taxes. The Company has an option to extend the expiration of the Suite 150 First Amendment for one month or nine months, at its discretion, by providing notice as specified in the Suite 150 First Amendment. On September 1, 2021, the Company entered into an agreement to extend the lease term to January 31, 2022 for approximately $46,000 a month. 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 had the option to extend the lease term of this facility for an additional five-year 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. In December 2019, the Company entered into an agreement to extend the lease term to December 18, 2024 for approximately $20,500 a month. In June 2020, the Company amended the lease agreement to further increase the rentable space to 13,139 square feet and extend the lease term to September 30, 2025 for approximately $34,500 a month. 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 to 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. On May 1, 2019, the Company entered into an agreement to extend the lease term to January 31, 2020 for approximately $4,000 a month. On October 24, 2019, the Company entered into an agreement to extend the lease term to April 30, 2020 for approximately $4,000 a month. On January 23, 2020, the Company entered into an agreement to extend the lease term to July 31, 2020 for approximately $4,000 a month. On May 24, 2020, the Company entered into an agreement to extend the lease term to October 31, 2020 for approximately $4,000 a month. On September 1, 2020, the Company entered into an agreement to extend the lease term to January 31, 2021, for approximately $4,000 a month. On January 31, 2021, the lease terminated, and the Company closed its New York office. Philadelphia Office Lease On May 2, 2019, the Company entered into an agreement to lease approximately 1,500 square feet of office space in Philadelphia, Pennsylvania until July 1, 2019 for a rate of $2,000 a month, and then approximately 4,500 square feet of office space for the remainder of a three-year term at an initial rate of $11,063 per month, subject to annual increases of 2.5%. On September 1, 2021, the Company entered into an agreement to extend the lease term for additional three years On August 1, 2020, the Company entered into an agreement to lease approximately 2,965 square feet of a training facility space in Philadelphia, Pennsylvania for a twelve-month term at a rate of approximately $6,500 per month. On August 9, 2021, the lease terminated. Commercial Manufacturing Facility Agreement On May 28, 2019, the Company entered into a lease agreement with 300 Rouse Boulevard, LLC (the “Commercial Manufacturing Facility Lease”) for a build-to-suit commercial manufacturing facility, laboratories, and offices located in Philadelphia, Pennsylvania. Under the Commercial Manufacturing Facility Lease, the Company leases approximately 136,000 rentable square feet of space in a building located at 300 Rouse Boulevard, Philadelphia, Pennsylvania known as its Iovance Cell Therapy Center or i i The Company determined the commencement date of the Commercial Manufacturing Lease to be October 7, 2020 in accordance with Topic 842 when its landlord made the Premise available for the Company’s use and the Company obtained control over the use of the i The Company’s monthly base rent under the Lease will be approximately $320,000, subject to an annual increase of 2% for the first ten years, and an annual increase of the greater of 2% or 75% of the average ten-year consumer price index. The Company is also responsible for paying operating expenses, which are expected to be approximately $72,000 per month in 2021. Manufacturing Contracts The Company uses contract manufacturing organizations (collectively the “CMOs” and each a “CMO”) to manufacture and supply TILs for clinical and commercial purposes. The CMO contractual obligations consist of the use of manufacturing facilities and minimum fixed commitment fees, such as personnel, general support fees, and minimum production or material fees. In addition to the minimum fixed commitment fees, the CMO contractual obligations include variable costs such as production and material costs in excess of the minimum quantity specified in each CMO agreement. During the term of each CMO agreement, the Company has access to and control of the use of a dedicated suite in each of the CMOs’ facilities for manufacturing activities. In conjunction with the adoption of Topic 842 on January 1, 2019, the Company reevaluated all its material contracts it has, to determine whether they contain a lease under Topic 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 this evaluation, the Company concluded that all its contracts with CMOs contained embedded operating leases because the suites used for its production are implicitly identified, is 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 the economic benefits from the use of the facilities and direct the use of the facilities throughout the period of use. The terms of the CMO contracts include options to terminate the lease with an advance notice of five to six months. The termination clauses and extension clauses are included in the calculation of the lease term for each of the CMOs when it is reasonably certain that it will not exercise such options. The guidance requires the Company to first identify a lease deliverable and non-lease deliverable included in the arrangements, and then allocate the fixed contractual consideration to the lease deliverable(s) and the non-lease deliverable(s) on a relative standalone selling price basis to determine the amount of operating lease right-of-use assets and liabilities. The Company identified the use of a dedicated suite as a single lease deliverable, and related labor services as a single non-lease deliverable in each of the CMO arrangements. Judgment is required to determine the relative standalone selling price of each deliverable as the observable standalone selling prices are not readily available. Therefore, management used estimates and assumptions in determining relative standalone selling price of lease of a suite and labor service using information that includes market and other observable inputs to the extent possible. The Company leases certain furniture and equipment that has a lease term of 12 months or less. Since the commencement date does not include an option to purchase the underlying asset, the Company elected not to apply the recognition requirements of Topic 842 for short-term leases, however, the lease costs that pertain to the short-term leases are disclosed in the components of lease costs table below. The balance sheet classification of the Company’s right-of-use asset and lease liabilities was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 December 31, 2020 Operating lease right-of-use assets $ 72,423 ​ $ 54,756 Operating lease liabilities ​ ​ ​ ​ Current portion included in current liabilities ​ 6,616 ​ 6,284 Long-term portion included in non-current liabilities ​ 64,729 ​ 45,375 Total operating lease liabilities $ 71,345 ​ $ 51,659 ​ The following table summarizes components of lease expenses, which were included in Total costs and expenses in the Company’s Condensed Consolidated Statement of Operations, and other information related to its operating leases as follows (in thousands except weighted-average remaining lease terms and discount rates): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ ​ 2021 ​ 2020 ​ 2021 ​ 2020 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease cost ​ $ 4,053 ​ $ 1,652 ​ $ 10,831 ​ $ 5,361 Variable lease cost ​ 1,484 ​ 1,702 ​ ​ 3,772 ​ ​ 4,333 Short-term lease cost ​ 26 ​ 26 ​ ​ 101 ​ ​ 57 Total lease cost ​ $ 5,563 ​ $ 3,380 ​ $ 14,704 ​ $ 9,751 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other information ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities included in operating cashflows ​ $ 3,605 ​ $ 1,893 ​ $ 8,439 ​ $ 5,995 Right-of-use assets obtained from entering new leases ​ $ 16,999 ​ $ 4,667 ​ $ 17,617 ​ $ 4,667 Increase in right-of-use assets from lease modifications ​ $ 5,853 ​ $ 206 ​ $ 7,796 ​ $ 534 Weighted-average remaining lease terms (years) ​ ​ ​ ​ ​ ​ ​ ​ 15.25 ​ ​ 1.71 Weighted-average discount rates ​ ​ ​ ​ ​ ​ ​ ​ 7.2% ​ ​ 7.5% ​ Variable lease cost is determined based on performance or usage in accordance with the contractual agreements, and not based on an index or rate. As of September 30, 2021, the maturities of the Company’s operating lease liabilities were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CMO ​ ​ ​ ​ Facility ​ embedded ​ ​ ​ ​ ​ leases leases Total Remainder of 2021 ​ $ 1,542 ​ $ 2,150 ​ $ 3,692 2022 ​ 5,401 ​ 4,091 ​ 9,492 2023 ​ 8,006 ​ — ​ 8,006 2024 ​ 8,206 ​ — ​ 8,206 2025 ​ 8,107 ​ — ​ 8,107 Thereafter ​ 99,931 ​ — ​ 99,931 Total lease payments ​ $ 131,193 ​ $ 6,241 ​ $ 137,434 Less: Present value adjustment ​ (65,908) ​ (181) ​ (66,089) Operating lease liabilities ​ $ 65,285 ​ $ 6,060 ​ $ 71,345 ​ Operating lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. In determining the present value of lease payments, the Company used its incremental borrowing rate based on the information available at the date of adoption of Topic 842 or the date of lease modifications.

LONG-TERM NOTE

LONG-TERM NOTE	9 Months Ended
	Sep. 30, 2021
LONG-TERM NOTE PAYABLE
LONG-TERM NOTE	NOTE 11. LONG-TERM NOTE PAYABLE On January 26, 2021, the Company entered into a Loan Note and accompanying Economic Stimulus Program Loan Agreement with PIDC – Local Development Corporation, a Pennsylvania nonprofit corporation (the “Lender”), pursuant to which the Lender agreed to make a loan (the “Job Creation Loan”) to the Company in a principal amount of $1.0 million. The Job Creation Loan will be for a term of five years starting on February 18, 2021, the date of the issuance of a final certificate of occupancy for the Company’s leased premises in Philadelphia, Pennsylvania. The Job Creation Loan is unsecured, bears no interest, and will be forgiven by the Lender in the amount of $2,000 per full-time or “full time equivalent” (defined as two or more part time employees whose working hours total at least 35 hours a week) employee with an average salary of at least $80,000 (“FT Employees”), up to a maximum amount equal to the amount of the Job Creation Loan, as calculated based on the average number of FT Employees employed at the Company’s premises during the period of the 5-year The Company concluded that it is not reasonably assured that all or a portion of the loan will be forgiven as of September 30, 2021, and therefore accounted for the Job Creation Loan as debt in accordance with ASC Topic 470, Debt

RELATED PARTY TRANSACTIONS

RELATED PARTY TRANSACTIONS	9 Months Ended
	Sep. 30, 2021
RELATED PARTY TRANSACTIONS
RELATED PARTY TRANSACTIONS	NOTE 12. RELATED PARTY TRANSACTIONS 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 million in stock-based compensation expense related to this consulting agreement for the three and nine months ended September 30, 2020, respectively.

INCOME TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2021
INCOME TAXES
INCOME TAXES	NOTE 13. INCOME TAXES The Company did not record income tax expenses for the three and nine months ended September 30, 2021 and 2020, respectively as the Company expected to be in a taxable loss position in 2021 and 2020, and the net deferred tax assets are fully offset by a valuation allowance as it is not more likely than not that the benefit will be realized. Therefore, the Company’s effective tax rate was 0.0% , for the three and nine months ended September 30, 2021 and 2020, respectively. As of September 30, 2021, the Company remains in a cumulative book loss position and does not have sufficient positive evidence to realize its net deferred tax assets. As such, the Company continues to maintain a full valuation allowance against its net deferred tax assets.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2021
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Cash, Cash Equivalents, Restricted Cash and Investments	Cash, Cash Equivalents, and 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 investments are classified as “available-for-sale” and are presented at fair value as either a current or non-current asset based on the length of maturity from the reporting date. Unrealized gains and losses on available-for-sale securities are included in accumulated other comprehensive income. Impairment losses related to credit losses (if any) are included in an allowance for credit losses with an offsetting entry to net loss. No impairment losses related to credit losses were recognized for the three and nine months ended September 30, 2021 and 2020. 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 Interest income, net in the Condensed Consolidated Statements of Operations. Gains and losses on securities sold are recorded based on the specific identification method and are included in Interest income, net in the Condensed Consolidated Statements 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 commercial papers, and places restrictions on maturities and concentration by type and issuer, except for securities issued by the U.S. government. Restricted Cash The Company maintains a required minimum balance, currently $6.1 million in a segregated bank account in connection with three letters of credit, one for $5.45 million for the benefit of the landlord for its commercial manufacturing facility used as a security deposit for the lease (See Note 10 - Leases), the second one for $74,685 for the benefit of a utilities service provider, and the third one for $559,082 for the benefit of the landlord for the Company’s new headquarters lease. The total amount is classified as Restricted Cash on the Condensed Consolidated Balance Sheet. The first letter of credit originally expired on May 28, 2020, however, it automatically extends for additional one-year periods, without written agreement, to May 28 in each succeeding calendar year, through at least 60 days after the lease expiration date. Further, on the expiration of the seventh year of the lease, and each anniversary date thereafter, the letter of credit may be decreased by $1.0 million, with a minimum security deposit of $1.45 million maintained through the end of the lease term. The second letter of credit of $74,685 expired on March 9, 2021, however, it automatically extends, without written agreement, to the expiration date of December 1, 2022. The third letter of credit of $559,082 expires on February 1, 2032, however, it will be automatically extended, without written agreement, for one-year periods to February in each succeeding calendar year. As of September 30, 2021, and December 31, 2020, restricted cash consisted of $6.1 million and $5.5 million, respectively. This amount has been classified as a non-current asset on the Company’s Condensed Consolidated Balance Sheets. The following table provides a reconciliation of cash, cash equivalents, and restricted cash, reported within the Condensed Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Condensed Consolidated Statements of Cash Flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, September 30, ​ ​ 2021 ​ 2020 ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 58,590 ​ $ 68,310 Restricted cash ​ 6,084 ​ 5,525 Total cash, cash equivalents and restricted cash ​ $ 64,674 ​ $ 73,835 ​
Loss per Share	Loss per Share Basic net loss per share is computed by dividing the net loss by the weighted average number of shares of common stock 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 shares of common stock issuable upon (i) the exercise of outstanding stock options and warrants, (ii) purchases though the 2020 Employee Stock Purchase Plan (the “2020 ESPP”), (iii) vesting of restricted stock units, and (iv) conversion of preferred stock, are only included in the calculation of diluted net loss per share when their effect is dilutive. As of September 30, 2021 and 2020, the following outstanding common stock equivalents have been excluded from the calculation of net loss per share because their impact would be anti-dilutive: ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ ​ 2021 2020 Stock options ​ 12,537,858 12,768,881 Series A Convertible Preferred Stock* ​ 97,000 97,000 Series B Convertible Preferred Stock* ​ 2,842,158 3,581,119 2020 ESPP ​ 36,263 ​ — Restricted stock units ​ 1,160,300 — ​ ​ 16,673,579 16,447,000 ​ * on an as-converted basis The effect of potentially dilutive securities would be reflected in diluted earnings per share of common stock 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 Accounting Standards Codification (“ASC”) 820, Fair Value Measurements and Disclosures 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–These are investments where values are based on unadjusted quoted prices for identical assets in an active market that the Company has the ability to access. Level 2–These are investments where values are based on quoted market prices in markets that are not active or model derived valuations in which all significant inputs are observable in active markets. Level 3–These are financial instruments where values are derived from techniques in which one or more significant inputs are unobservable. The Company’s financial instruments consist of cash, cash equivalents, short and long-term investments, and long-term notes payable, all of which are reported at their respective fair value on its Condensed Consolidated Balance Sheets. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company’s financial instruments consist of Level 1 and Level 2 assets. Where quoted prices are available in an active market, securities are classified as Level 1. When quoted market prices are not available for a specific security, the Company estimates the fair value by using quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Where applicable, these models project future cash flows and discount the future amounts to a present value using market-based observable inputs obtained from various third-party data providers, including but not limited to, benchmark yields, interest rate curves, reported trades, broker/dealer quotes, and market reference data. Level 2 assets consist of commercial paper and government agency securities. Level 2 inputs for the valuations are limited to quoted prices for similar assets or liabilities in active markets and inputs other than quoted prices that are observable for the asset. As of September 30, 2021 and December 31, 2020, the fair value of the Company’s financial assets, which consist of cash equivalents and short and long-term investments classified as available-for-sale securities, that were measured 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 September 30, 2021 ​ Level 1 Level 2 Level 3 Total U.S. treasury securities ​ $ 238,238 ​ $ — ​ $ — ​ $ 238,238 U.S. government agency securities ​ — ​ 12,233 ​ — ​ 12,233 Corporate securities ​ ​ — ​ ​ 43,308 ​ ​ — ​ ​ 43,308 Commercial paper ​ ​ — ​ ​ 312,325 ​ ​ — ​ ​ 312,325 Money market funds ​ ​ 32,577 ​ ​ — ​ ​ — ​ ​ 32,577 Total ​ $ 270,815 ​ $ 367,866 ​ $ — ​ $ 638,681 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Assets at Fair Value as of December 31, 2020 ​ Level 1 Level 2 Level 3 Total US treasury securities ​ $ 470,109 ​ $ — ​ $ — ​ $ 470,109 US government agency securities ​ 91,999 ​ — ​ — ​ 91,999 Money market funds ​ ​ 49,720 ​ ​ — ​ ​ — ​ ​ 49,720 Total ​ $ 611,828 ​ $ — ​ $ — ​ $ 611,828 ​ The available-for-sale securities in the Company’s Condensed Consolidated Balance Sheets are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 42,575 ​ $ 49,720 Short-term investments ​ ​ 517,859 ​ ​ 562,108 Long-term investments ​ ​ 78,247 ​ ​ — Cash equivalents and investments total ​ $ 638,681 ​ $ 611,828
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with 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 the assumptions made in valuing stock instruments issued for services and used in measuring operating right-of-use assets and operating lease liabilities, accounting for potential liabilities, capitalization of internal-use software development costs, and the valuation allowance associated with the Company’s deferred tax assets.
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements include the accounts of Iovance Biotherapeutics, Inc. and its wholly-owned subsidiaries, Iovance Biotherapeutics Manufacturing LLC, Iovance Biotherapeutics GmbH, and Iovance Biotherapeutics B.V . All intercompany accounts and transactions have been eliminated. The U.S. dollar is the functional currency for all the Company's consolidated operations.
Income Taxes	Income Taxes On March 27, 2020, the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”) was enacted and signed into law, and GAAP requires recognition of the tax effects of new legislation during the reporting period that includes the enactment date. The CARES Act, among other things, includes changes to the tax provisions that benefits business entities and makes certain technical corrections to the 2017 Tax Cuts and Jobs Act. The tax relief measures for business entities include a five-year net operating loss carrybacks, suspension of annual deduction limitation of 80% taxable income from net operating losses generated in a tax year beginning after December 31, 2017, changes in the deductibility of interest, acceleration of alternative minimum tax credit refunds, payroll tax relief, and technical correction to allow accelerated deductions for qualified improvement property. The Company evaluated the impact of the CARES Act and determined the impact is immaterial for the three and nine months ended September 30, 2021.
Leases	The Company determines if an arrangement includes a lease at inception. Operating leases are included in its Condensed Consolidated Balance Sheet as Operating lease right-of-use assets and Operating lease liabilities as of September 30, 2021 and December 31, 2020. Operating lease right-of-use assets represent the Company’s right to use an underlying asset for the lease term and operating lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the net present value of lease payments, the Company uses an estimated incremental borrowing rate that is applicable to the Company based on the information available at the later of the lease commencement date or the date of adoption of Accounting Standard Update (“ASU”) No. 2016-02 and ASU No. 2018-10, Leases (together “Topic 842”). The operating lease right-of-use assets also include any lease payments made less lease incentives. The Company’s leases may include options to extend or terminate the lease, which is considered in the lease term when it is reasonably certain that the Company will exercise any such options. Lease expense is recognized on a straight-line basis over the expected lease term. The Company has elected not to apply the recognition requirements of Topic 842 for short-term leases. For lease agreements entered into after the adoption of Topic 842 that include lease and non-lease components, such components are generally accounted for separately.
Stock-Based Compensation	Stock-Based Compensation The Company periodically grants stock options to employees as compensation for services rendered. The Company accounts for all stock-based payment awards made to employees, including the employee stock purchase plans in accordance with the authoritative guidance provided by the Financial Accounting Standards Board (“FASB”) where the value of the award is measured on the date of grant and recognized over the vesting period. In accordance with ASU No. 2018-07, Compensation-Stock Compensation 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 term of the common stock options, and future dividends. The stock-based 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 issues restricted stock units (“RSUs”) and restricted stock awards (“RSAs”) from time to time as part of its share-based compensation programs. The Company measures the compensation cost with respect to RSUs and RSAs 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 awards. The fair value of RSUs and RSAs is based on the closing price of the Company’s common stock on the grant date.
Accrued Research and Development Costs	Accrued Research and Development Costs Research and development costs are expensed as incurred. Clinical development costs compose a significant component of research and development costs. The Company has a history of contracting with third parties that perform various clinical trial activities on its behalf. Service agreements with contract research organizations (“CROs”) and contract manufacturing organizations (“CMOs”) are recognized as the services are incurred. The Company accrues for expenses resulting from obligations under agreements with its third parties for which the timing of payments does not match the periods over which the materials or services are provided to the Company. Accruals are recorded based on estimates of services received and efforts expended pursuant to agreements established with CROs, CMOs and other outside service providers. These estimates are typically based on contracted amounts applied to the proportion of work performed and determined through analysis with internal personnel and external service providers as to the progress or stage of completion of the services. The Company makes judgements and estimates in determining the accrual balance in each reporting period. In the event advance payments are made to a CRO, CMO or other outside service provider, the payments are recorded within prepaid expenses and other current assets and subsequently recognized as research and development expense when the associated services have been performed. As actual costs become known, the Company adjusts its liabilities and assets. Inputs, such as the extent of services received and the duration of services to be performed, may vary from the Company’s estimates, which will result in adjustments to research and development expense in future periods. Changes in these estimates that result in material changes to the Company’s accruals could materially affect the Company’s results of operations. The Company’s historical estimates have not been materially different from actual amounts recorded.
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 stock subject to mandatory redemption are classified as liability instruments and are measured at fair value. Conditionally redeemable preferred stock (including preferred stock 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 stock is classified as stockholders’ equity.
Recent Accounting Standards	Recent Accounting Standards Adopted In December 2019, the FASB issued ASU No. 2019-12, Income Taxes Simplifying the Accounting for Income Taxes,

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	9 Months Ended
	Sep. 30, 2021
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Schedule of cash and cash equivalents and restricted cash	The following table provides a reconciliation of cash, cash equivalents, and restricted cash, reported within the Condensed Consolidated Balance Sheets that sum to the total of the same such amounts shown in the Condensed Consolidated Statements of Cash Flows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, September 30, ​ ​ 2021 ​ 2020 ​ ​ ​ ​ ​ ​ ​ Cash and cash equivalents ​ $ 58,590 ​ $ 68,310 Restricted cash ​ 6,084 ​ 5,525 Total cash, cash equivalents and restricted cash ​ $ 64,674 ​ $ 73,835
Schedule of Antidilutive securities excluded from computation of earnings per share	​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ ​ 2021 2020 Stock options ​ 12,537,858 12,768,881 Series A Convertible Preferred Stock* ​ 97,000 97,000 Series B Convertible Preferred Stock* ​ 2,842,158 3,581,119 2020 ESPP ​ 36,263 ​ — Restricted stock units ​ 1,160,300 — ​ ​ 16,673,579 16,447,000 ​ * on an as-converted basis
Schedule of assets measured at fair value	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Assets at Fair Value as of September 30, 2021 ​ Level 1 Level 2 Level 3 Total U.S. treasury securities ​ $ 238,238 ​ $ — ​ $ — ​ $ 238,238 U.S. government agency securities ​ — ​ 12,233 ​ — ​ 12,233 Corporate securities ​ ​ — ​ ​ 43,308 ​ ​ — ​ ​ 43,308 Commercial paper ​ ​ — ​ ​ 312,325 ​ ​ — ​ ​ 312,325 Money market funds ​ ​ 32,577 ​ ​ — ​ ​ — ​ ​ 32,577 Total ​ $ 270,815 ​ $ 367,866 ​ $ — ​ $ 638,681 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Assets at Fair Value as of December 31, 2020 ​ Level 1 Level 2 Level 3 Total US treasury securities ​ $ 470,109 ​ $ — ​ $ — ​ $ 470,109 US government agency securities ​ 91,999 ​ — ​ — ​ 91,999 Money market funds ​ ​ 49,720 ​ ​ — ​ ​ — ​ ​ 49,720 Total ​ $ 611,828 ​ $ — ​ $ — ​ $ 611,828
Schedule of available-for-sale securities in the Company's Consolidated Balance Sheet	The available-for-sale securities in the Company’s Condensed Consolidated Balance Sheets are as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 42,575 ​ $ 49,720 Short-term investments ​ ​ 517,859 ​ ​ 562,108 Long-term investments ​ ​ 78,247 ​ ​ — Cash equivalents and investments total ​ $ 638,681 ​ $ 611,828

CASH EQUIVALENTS AND INVESTME_2

CASH EQUIVALENTS AND INVESTMENTS (Tables)	9 Months Ended
	Sep. 30, 2021
CASH EQUIVALENTS AND INVESTMENTS
Schedule of cash, money market funds and short-term investments	Cash equivalents consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 ​ ​ ​ ​ ​ ​ ​ Cash equivalents ​ $ 42,575 ​ $ 49,720 Cash equivalents total ​ $ 42,575 ​ $ 49,720
Schedule of available-for-sale debt securities	The following table summarizes the Company’s investments that are classified as available-for-sale debt securities (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 ​ ​ ​ ​ ​ ​ ​ Short-term investments ​ $ 517,859 ​ $ 562,108 Long-term investments ​ ​ 78,247 ​ ​ — Total investments ​ $ 596,106 ​ $ 562,108
Schedule of cost and fair value of cash equivalents and short-term investments	The following table summarizes the classification of the Company’s available-for-sale debt securities in its Condensed Consolidated Balance Sheets (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, Investments ​ 2021 2020 U.S. treasury securities ​ $ 238,238 ​ $ 470,109 U.S. government agency securities ​ 12,233 ​ 91,999 Corporate securities ​ ​ 43,308 ​ ​ — Commercial paper ​ 302,327 ​ — Total investments ​ $ 596,106 ​ $ 562,108 ​ The cost and fair value of investments as of September 30, 2021 and December 31, 2020 were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ ​ ​ As of September 30, 2021 Cost Gains Losses Fair Value U.S. treasury securities ​ $ 238,252 ​ $ 17 ​ $ (31) ​ $ 238,238 U.S. government agency securities ​ 12,233 ​ — ​ — ​ 12,233 Corporate securities ​ ​ 43,325 ​ ​ — ​ ​ (17) ​ ​ 43,308 Commercial papers ​ ​ 302,303 ​ ​ 37 ​ ​ (13) ​ ​ 302,327 Total investments ​ $ 596,113 ​ $ 54 ​ $ (61) ​ $ 596,106 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Gross ​ Gross ​ ​ ​ ​ ​ Amortized ​ Unrealized ​ Unrealized ​ ​ ​ As of December 31, 2020 Cost Gains Losses Fair Value U.S. treasury securities ​ $ 470,108 ​ $ 30 ​ $ (29) ​ $ 470,109 U.S. government agency securities ​ 91,981 ​ 20 ​ (2) ​ 91,999 Total investments ​ $ 562,089 ​ $ 50 ​ $ (31) ​ $ 562,108
Schedule of available-for-sale debt securities by contractual maturity	The following table summarizes the Company’s available-for-sale debt securities by contractual maturity (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 ​ ​ Amortized Cost Fair Value ​ ​ ​ ​ ​ ​ ​ Within one year ​ $ 517,835 ​ $ 517,859 One year to two years ​ ​ 78,278 ​ ​ 78,247 Total investments ​ $ 596,113 ​ $ 596,106

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	9 Months Ended
	Sep. 30, 2021
PROPERTY AND EQUIPMENT
Schedule of Property and equipment	Property and equipment, net consists of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ 2021 2020 Lab equipment ​ $ 12,051 ​ $ 4,656 Leasehold improvements ​ 57,817 ​ 2,573 Computer equipment ​ 1,163 ​ 270 Computer software ​ ​ 674 ​ ​ — Office furniture and equipment ​ 1,244 ​ 480 Machinery and equipment ​ ​ 82 ​ ​ — Construction in progress ​ 22,347 ​ 56,758 Total property and equipment, cost ​ 95,378 ​ 64,737 Less: Accumulated depreciation and amortization ​ (7,344) ​ (5,578) Property and equipment, net ​ $ 88,034 ​ $ 59,159

ACCRUED EXPENSES (Tables)

ACCRUED EXPENSES (Tables)	9 Months Ended
	Sep. 30, 2021
ACCRUED EXPENSES
Schedule of accrued expenses	Accrued expenses consist of the following (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ September 30, ​ December 31, ​ ​ 2021 2020 ​ ​ ​ ​ ​ ​ ​ Clinical related ​ $ 12,577 ​ $ 15,661 Accrued payroll and employee related expenses ​ ​ 15,167 ​ ​ 9,032 R&D manufacturing related ​ 9,108 ​ 3,266 Facilities related ​ ​ 5,082 ​ ​ 4,342 Legal and related services ​ 1,671 ​ 1,061 Accrued other ​ 2,364 ​ 1,712 Total accrued expenses ​ $ 45,969 ​ $ 35,074

STOCK BASED COMPENSATION (Table

STOCK BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2021
STOCK BASED COMPENSATION
Schedule of status of stock options	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ ​ ​ ​ Weighted ​ Average ​ Aggregate ​ ​ Number ​ Average ​ Remaining ​ Intrinsic ​ ​ of ​ Exercise ​ Contract ​ Value ​ Options ​ Price Life (in thousands) Outstanding as of December 31, 2020 ​ 12,615,638 ​ $ 18.08 ​ ​ ​ ​ ​ Granted ​ 5,023,599 ​ 39.82 ​ ​ ​ Exercised ​ (2,559,361) ​ 11.72 ​ ​ ​ Expired/Forfeited ​ (2,542,018) ​ 32.20 ​ ​ ​ Outstanding and vested as of September 30, 2021 ​ 12,537,858 ​ $ 25.22 ​ 7.70 ​ $ 65,954 ​ ​ ​ ​ ​ ​ ​ ​ Options exercisable as of September 30, 2021 ​ 6,233,363 ​ $ 15.74 ​ 6.34 ​ $ 60,233
Schedule of stock-based compensation	Total stock-based compensation expenses related to all of the Company’s stock-based awards were recorded on the Statements of Operations as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2021 2020 2021 2020 ​ Research and development ​ $ 11,504 ​ $ 5,282 ​ $ 29,291 ​ $ 15,065 ​ General and administrative ​ 7,802 ​ 5,424 ​ 21,370 ​ 15,590 ​ Total stock-based compensation expenses ​ $ 19,306 ​ $ 10,706 ​ $ 50,661 ​ $ 30,655 ​ ​ Total stock-based compensation expense by type of award was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ ​ September 30, ​ September 30, ​ ​ 2021 2020 ​ 2021 2020 ​ Stock option expenses ​ $ 13,339 ​ $ 10,706 ​ $ 42,782 ​ $ 30,543 ​ Restricted stock unit expenses ​ 5,788 ​ — ​ 6,887 ​ 112 ​ 2020 ESPP expenses ​ 179 ​ — ​ 992 ​ — ​ Total stock-based compensation expenses ​ $ 19,306 ​ $ 10,706 ​ $ 50,661 ​ $ 30,655 ​
Schedule of summary of RSU activity	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Weighted ​ ​ ​ Number ​ Average ​ ​ ​ of ​ Grant Date ​ ​ RSUs Fair Value ​ Outstanding, non-vested as of December 31, 2020 ​ — ​ $ — ​ Granted ​ 1,253,540 ​ ​ 23.87 ​ Vested ​ — ​ ​ — ​ Canceled/Forfeited ​ (93,240) ​ ​ 23.87 ​ Outstanding, non-vested as of September 30, 2021 ​ 1,160,300 ​ $ 23.87 ​ ​ ​ ​ ​ ​ ​ ​

LEASES (Tables)

LEASES (Tables)	9 Months Ended
	Sep. 30, 2021
LEASES
Schedule of balance sheet classification of the Company's right-of-use asset and lease liabilities	The balance sheet classification of the Company’s right-of-use asset and lease liabilities was as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ September 30, 2021 December 31, 2020 Operating lease right-of-use assets $ 72,423 ​ $ 54,756 Operating lease liabilities ​ ​ ​ ​ Current portion included in current liabilities ​ 6,616 ​ 6,284 Long-term portion included in non-current liabilities ​ 64,729 ​ 45,375 Total operating lease liabilities $ 71,345 ​ $ 51,659
Schedule of components of lease expenses	The following table summarizes components of lease expenses, which were included in Total costs and expenses in the Company’s Condensed Consolidated Statement of Operations, and other information related to its operating leases as follows (in thousands except weighted-average remaining lease terms and discount rates): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended ​ Nine Months Ended ​ ​ September 30, ​ September 30, ​ ​ 2021 ​ 2020 ​ 2021 ​ 2020 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Operating lease cost ​ $ 4,053 ​ $ 1,652 ​ $ 10,831 ​ $ 5,361 Variable lease cost ​ 1,484 ​ 1,702 ​ ​ 3,772 ​ ​ 4,333 Short-term lease cost ​ 26 ​ 26 ​ ​ 101 ​ ​ 57 Total lease cost ​ $ 5,563 ​ $ 3,380 ​ $ 14,704 ​ $ 9,751 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Other information ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Cash paid for amounts included in the measurement of lease liabilities included in operating cashflows ​ $ 3,605 ​ $ 1,893 ​ $ 8,439 ​ $ 5,995 Right-of-use assets obtained from entering new leases ​ $ 16,999 ​ $ 4,667 ​ $ 17,617 ​ $ 4,667 Increase in right-of-use assets from lease modifications ​ $ 5,853 ​ $ 206 ​ $ 7,796 ​ $ 534 Weighted-average remaining lease terms (years) ​ ​ ​ ​ ​ ​ ​ ​ 15.25 ​ ​ 1.71 Weighted-average discount rates ​ ​ ​ ​ ​ ​ ​ ​ 7.2% ​ ​ 7.5%
Schedule of minimum lease commitments	As of September 30, 2021, the maturities of the Company’s operating lease liabilities were as follows (in thousands): ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ CMO ​ ​ ​ ​ Facility ​ embedded ​ ​ ​ ​ ​ leases leases Total Remainder of 2021 ​ $ 1,542 ​ $ 2,150 ​ $ 3,692 2022 ​ 5,401 ​ 4,091 ​ 9,492 2023 ​ 8,006 ​ — ​ 8,006 2024 ​ 8,206 ​ — ​ 8,206 2025 ​ 8,107 ​ — ​ 8,107 Thereafter ​ 99,931 ​ — ​ 99,931 Total lease payments ​ $ 131,193 ​ $ 6,241 ​ $ 137,434 Less: Present value adjustment ​ (65,908) ​ (181) ​ (66,089) Operating lease liabilities ​ $ 65,285 ​ $ 6,060 ​ $ 71,345

GENERAL ORGANIZATION AND BUSI_2

GENERAL ORGANIZATION AND BUSINESS (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
GENERAL ORGANIZATION AND BUSINESS
Net Loss	$ 86,122	$ 58,571	$ 242,922	$ 191,184
Net cash used in operating activities			174,092	142,442
Proceeds from the issuance of common stock, net			203,156	567,043
Cash equivalents, short-term investments, and restricted cash	660,800		660,800
Cash and cash equivalents	58,590	68,310	58,590	68,310	$ 67,329
Short-term investments	517,859		517,859		562,108
Long-term investments	78,247		78,247
Restricted cash	$ 6,084	$ 5,525	$ 6,084	$ 5,525	$ 5,525

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Cash, Cash equivalents and Restricted Cash (Details) - USD ($)	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020	Dec. 31, 2019
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Security deposit	$ 1,450,000
Security deposit for the benefit of the landlord for its commercial manufacturing facility	5,450,000
Security deposit for the benefit of utilities service provider	74,685
Benefit of landlord	559,082
Letter of credit	1,000,000
Cash and cash equivalents	58,590,000	$ 67,329,000	$ 68,310,000
Restricted cash	6,084,000	5,525,000	5,525,000
Total cash, cash equivalents and restricted cash	$ 64,674,000	$ 72,854,000	$ 73,835,000	$ 19,419,000

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Loss per share (Details) - shares	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Antidilutive securities excluded from calculation of net loss per share	16,673,579	16,447,000
Stock option
Antidilutive securities excluded from calculation of net loss per share	12,537,858	12,768,881
Employee Stock Purchase Plan
Antidilutive securities excluded from calculation of net loss per share	36,263
Restricted stock units
Antidilutive securities excluded from calculation of net loss per share	1,160,300
Series A Preferred Stock
Antidilutive securities excluded from calculation of net loss per share	97,000	97,000
Series B Convertible Preferred Stock
Antidilutive securities excluded from calculation of net loss per share	2,842,158	3,581,119

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Fair value (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Total	$ 638,681	$ 611,828
U.S. treasury securities
Total	238,238	470,109
U.S. government agency securities
Total	12,233	91,999
Corporate Securities Member
Total	43,308
Commercial paper
Total	312,325
Money market funds
Total	32,577	49,720
Level 1
Total	270,815	611,828
Level 1 | U.S. treasury securities
Total	238,238	470,109
Level 1 | U.S. government agency securities
Total		91,999
Level 1 | Money market funds
Total	32,577	$ 49,720
Level 2
Total	367,866
Level 2 | U.S. government agency securities
Total	12,233
Level 2 | Corporate Securities Member
Total	43,308
Level 2 | Commercial paper
Total	$ 312,325

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Available-for-sale of securities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
Cash equivalents	$ 42,575	$ 49,720
Short-term investments	517,859	562,108
Long-term investments	78,247
Cash Equivalents and Investments total	$ 638,681	$ 611,828

CASH EQUIVALENTS AND INVESTME_3

CASH EQUIVALENTS AND INVESTMENTS (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Cash equivalents total	$ 42,575	$ 49,720
Money market funds
Cash equivalents total	42,575	49,720
Demand Deposits
Cash equivalents total	$ 16,000	$ 17,600

CASH EQUIVALENTS AND INVESTME_4

CASH EQUIVALENTS AND INVESTMENTS - Available for sale debt securities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
CASH EQUIVALENTS AND INVESTMENTS
Short-term investments	$ 517,859	$ 562,108
Long-term investments	78,247
Investments total	$ 596,106	$ 562,108

CASH EQUIVALENTS AND INVESTME_5

CASH EQUIVALENTS AND INVESTMENTS - Short-term investments (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Investments total	$ 596,106	$ 562,108
U.S. treasury securities
Investments total	238,238	470,109
U.S. government agency securities
Investments total	12,233	$ 91,999
Corporate securities
Investments total	43,308
Commercial paper
Investments total	$ 302,327

CASH EQUIVALENTS AND INVESTME_6

CASH EQUIVALENTS AND INVESTMENTS - Cost and fair value (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Amortized Cost	$ 596,113	$ 562,089
Gross Unrealized Gains	54	50
Gross Unrealized Losses	(61)	(31)
Fair Value	596,106	562,108
U.S. treasury securities
Amortized Cost	238,252	470,108
Gross Unrealized Gains	17	30
Gross Unrealized Losses	(31)	(29)
Fair Value	238,238	470,109
U.S. government agency securities
Amortized Cost	12,233	91,981
Gross Unrealized Gains		20
Gross Unrealized Losses		(2)
Fair Value	12,233	$ 91,999
Corporate securities
Amortized Cost	43,325
Gross Unrealized Losses	(17)
Fair Value	43,308
Commercial paper
Amortized Cost	302,303
Gross Unrealized Gains	37
Gross Unrealized Losses	(13)
Fair Value	$ 302,327

CASH EQUIVALENTS AND INVESTME_7

CASH EQUIVALENTS AND INVESTMENTS - Contractual maturity (Details) $ in Thousands	Sep. 30, 2021USD ($)
Amortized Cost
Within one year	$ 517,835
One year to two years	78,278
Amortized cost investments total	596,113
Fair Value
Within one year	517,859
One year to two years	78,247
Total investments	$ 596,106

PROPERTY AND EQUIPMENT - (Detai

PROPERTY AND EQUIPMENT - (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment, cost	$ 95,378	$ 64,737
Less: Accumulated depreciation and amortization	(7,344)	(5,578)
Property and equipment, net	88,034	59,159
Lab equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, cost	12,051	4,656
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, cost	57,817	2,573
Computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, cost	1,163	270
Computer software
Property, Plant and Equipment [Line Items]
Total property and equipment, cost	674
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, cost	1,244	480
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, cost	82
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment, cost	$ 22,347	$ 56,758

PROPERTY AND EQUIPMENT - Other

PROPERTY AND EQUIPMENT - Other information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Property, Plant and Equipment [Line Items]
Depreciation	$ 1	$ 0.3	$ 1.8	$ 0.8
Commercial Manufacturing Facility Agreement
Property, Plant and Equipment [Line Items]
Depreciation	0.7		0.7
Tenant Improvements	$ 62.3		$ 62.3

ACCRUED EXPENSES (Details)

ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
ACCRUED EXPENSES
Clinical related	$ 12,577	$ 15,661
Accrued payroll and employee related expenses	15,167	9,032
R&D Manufacturing related	9,108	3,266
Facilities related	5,082	4,342
Legal and related services	1,671	1,061
Accrued other	2,364	1,712
Accrued expenses	$ 45,969	$ 35,074

STOCKHOLDERS' EQUITY (Details)

STOCKHOLDERS' EQUITY (Details) - USD ($) $ / shares in Units, $ in Thousands	Feb. 08, 2021	Jun. 30, 2020	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Common Stock
Common stock, shares authorized			300,000,000	300,000,000		300,000,000
Common stock, par or stated value per share			$ 0.000041666	$ 0.000041666		$ 0.000041666
Common stock, shares issued			156,702,653	156,702,653		146,874,917
Common stock, shares outstanding			156,702,653	156,702,653		146,874,917
Proceeds from the issuance of common stock, net				$ 203,156	$ 567,043
Common Stock
Common Stock
Common stock issued, net of offering costs (in shares)				6,474,099	19,475,806
Common Stock | Issuance Of Common Stock Upon Conversion Of Preferred Stock
Common Stock
Conversion of stock, shares issued				738,961
IPO
Common Stock
Common stock issued, net of offering costs (in shares)		16,935,484
Share price (in dollars per share)		$ 31
Proceeds from the issuance of common stock, net		$ 567,000
IPO | Underwriter
Common Stock
Common stock issued, net of offering costs (in shares)		2,540,322
Proceeds from the issuance of common stock		$ 603,700
At the Market Offering Program [Member]
Common Stock
Common stock issued, net of offering costs (in shares)			0	6,474,099
Proceeds from the issuance of common stock, net				$ 203,200
Maximum amount of shares to be issued	$ 350,000
Maximum percentage of commission	3.00%
Weighted average price				$ 32.12
Series A Convertible Preferred Stock
Common Stock
Preferred stock, shares authorized			17,000	17,000
Sale of stock, price per share			$ 2	$ 2
Preferred stock, par or stated value per share			$ 1,000	$ 1,000
Preferred stock, shares outstanding			194	194		194
Conversion of stock, shares issued				500
Conversion of Stock, shares converted				0	0
Series A Convertible Preferred Stock | Common Stock
Common Stock
Conversion of stock, shares issued				97,000		97,000
Series B Convertible Preferred Stock
Common Stock
Preferred stock, shares authorized			11,500,000	11,500,000		11,500,000
Preferred stock, par or stated value per share			$ 0.001	$ 0.001		$ 0.001
Convertible price per shares				$ 4.75
Preferred stock, shares outstanding			2,842,158	2,842,158		3,581,119
Conversion of stock, shares issued				1
Series B Convertible Preferred Stock | Issuance Of Common Stock Upon Conversion Of Preferred Stock
Common Stock
Conversion of stock, shares issued				738,961	0
Series B Convertible Preferred Stock | Common Stock
Common Stock
Preferred stock, shares outstanding			2,842,158	2,842,158		3,581,119
Series B Convertible Preferred Stock | IPO
Common Stock
Preferred stock, par or stated value per share			$ 4.75	$ 4.75
Blank check
Common Stock
Preferred stock, shares authorized			50,000,000	50,000,000

STOCK BASED COMPENSATION (Detai

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

Jun. 01, 2016

Jul. 31, 2013

Jun. 30, 2021

Jun. 30, 2020

Aug. 31, 2013

Sep. 30, 2021

Sep. 30, 2020

Sep. 30, 2021

Sep. 30, 2020

Sep. 22, 2021

Dec. 31, 2020

Jun. 08, 2020

Jun. 07, 2020

Apr. 22, 2018

Aug. 16, 2016

Apr. 10, 2015

Nov. 30, 2014

Aug. 20, 2014

Aug. 19, 2014

Oct. 14, 2011

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

Weighted average grant date fair value, options granted

$ 23.29

$ 16.37

2011 Equity Incentive Plan

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

Maximum award per person per year (in shares)

50,000

300,000

Number of shares available

500,000

11,240

11,240

Shares authorized

180,000

1,700,000

1,900,000

1,700,000

180,000

Award expiration term

10 years

Granted

0

Percentage of purchase price

85.00%

The 2018 Plan

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

Number of shares available

3,792,680

3,792,680

Shares authorized

14,000,000

6,000,000

6,000,000

2020 ESPP

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

Common Stock, Capital Shares Reserved for Future Issuance

55,315

55,315

Stock-based compensation expense

$ 0.2

$ 0

$ 1

$ 0

Unrecognized compensation cost

$ 0.1

$ 0.1

Unrecognized compensation cost recognition period

2 months 9 days

2014 Equity Incentive Plan

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

Number of shares available

80,551

80,551

Shares authorized

4,000,000

2,350,000

2014 Equity Incentive Plan | Maximum

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

Shares authorized

9,000,000

2021 Inducement Plan

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

Number of shares available

1,000,000

1,000,000

Shares authorized

1,000,000

Stock option

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

Total unrecognized compensation expense

$ 105.1

$ 105.1

Unrecognized compensation cost recognition period

1 year 11 months 4 days

Restricted stock units

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

Granted

1,253,540

1,253,540

Vested

137,500

Weighted Average Grant Date Fair Value, Granted

$ 23.87

Unvested shares

1,160,300

1,160,300

Unrecognized compensation cost recognition period

10 months 17 days

First Anniversary | Restricted stock units

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

Vested

137,500

Vesting period

36 months

Satisfaction Of Clinical Trial Milestones | Restricted stock units

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

Vested

275,000

Chief Executive Officer | Restricted stock units

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

Granted

550,000

Weighted Average Grant Date Fair Value, Granted

$ 5.87

Unvested shares

0

0

0

STOCK BASED COMPENSATION - Stoc

STOCK BASED COMPENSATION - Stock Options (Details) - Stock option - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2021
Number of Options
Outstanding, beginning balance	12,615,638
Granted	5,023,599
Exercised	(2,559,361)
Expired/Forfeited	(2,542,018)
Outstanding, ending balance	12,537,858
Options exercisable, number	6,233,363
Weighted Average Exercise Price
Outstanding, beginning balance	$ 18.08
Granted	39.82
Exercised	11.72
Expired/Forfeited	32.20
Outstanding, ending balance	25.22
Options exercisable, exercise price	$ 15.74
Weighted Average Remaining Contractual Life
Options outstanding, remaining term	7 years 8 months 12 days
Options exercisable, remaining term	6 years 4 months 2 days
Aggregate Intrinsic Value
Outstanding, end of period	$ 65,954
Exercisable	$ 60,233

STOCK BASED COMPENSATION - Rest

STOCK BASED COMPENSATION - Restricted stock unit (Details) - Restricted stock units - USD ($) $ / shares in Units, $ in Millions	Jun. 01, 2016	Jun. 30, 2021	Sep. 30, 2021
Number of Shares
Granted		1,253,540	1,253,540
Vested	(137,500)
Canceled/forfeited			(93,240)
Non-vested shares, Ending balance			1,160,300
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value, Granted			$ 23.87
Weighted Average Grant Date Fair Value, Canceled/forfeited			23.87
Weighted Average Grant Date Fair Value, Ending balance			$ 23.87
Unrecognized compensation cost			$ 20.8
Unrecognized compensation cost recognition period			10 months 17 days
Aggregate intrinsic value of outstanding nonvested RSUs			$ 28.6

STOCK BASED COMPENSATION- stock

STOCK BASED COMPENSATION- stock based expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Total stock-based compensation expenses	$ 19,306	$ 10,706	$ 50,661	$ 30,655
Research and development
Total stock-based compensation expenses	11,504	5,282	29,291	15,065
General and administrative
Total stock-based compensation expenses	$ 7,802	$ 5,424	$ 21,370	$ 15,590

STOCK BASED COMPENSATION - St_2

STOCK BASED COMPENSATION - Stock-based compensation by instrument (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Total stock-based compensation expenses	$ 19,306	$ 10,706	$ 50,661	$ 30,655
Stock option
Total stock-based compensation expenses	13,339	$ 10,706	42,782	30,543
Restricted stock units
Total stock-based compensation expenses	5,788		6,887	$ 112
2020 ESPP
Total stock-based compensation expenses	$ 179		$ 992

LICENSES AND AGREEMENTS (Detail

LICENSES AND AGREEMENTS (Details) $ in Thousands	Sep. 30, 2021USD ($)	May 07, 2018USD ($)	Apr. 17, 2017USD ($)	Jun. 28, 2014USD ($)	Aug. 31, 2011	Dec. 31, 2016	Nov. 30, 2016item	Aug. 31, 2016USD ($)	Jan. 31, 2015item	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)	Sep. 30, 2020USD ($)
Research and development expenses										$ 65,355	$ 43,050	$ 183,423	$ 149,276
Strategic Alliance Agreement
Research and development expenses										100	300	200	500
Maximum | Strategic Alliance Agreement
Research and development arrangement, contract to perform for others, costs incurred, gross			$ 14,200
Cooperative Research and Development Agreement
Agreement term					5 years			5 years
Research and development expenses								$ 500		500	500	1,500	1,500
Number Of Indications Under Agreement | item									4
Notification Period To Terminate Agreement								60 days
Research Collaboration And Clinical Grant Agreements With Moffitt
Agreement term						3 years
Research and development expenses										100	100	300	500
Moffitt License Agreement One
Agreement term				20 years
Research and development expenses										0	0	0	0
Payments for upfront licensing fee				$ 100
Moffitt License Agreement Two
Payments for upfront licensing fee		$ 100
Moffitt License Agreement Two, Amended and Restated
Payments for upfront licensing fee	$ 200
WuXi Apptech, Inc - Manufacturing and Services Agreement
Agreement term							3 years
Research and development expenses										4,500	2,800	12,700	16,200
Number Of Statements Of Work | item							2
Number Of Suites Under The Agreement | item							2
Cellectis S.A
Research and development expenses										100	$ 100	300	300
Novartis Pharma AG - License Agreement
Research and development expenses										$ 0		$ 0	$ 10,000

LEGAL PROCEEDINGS (Details)

LEGAL PROCEEDINGS (Details) - Solomon Capital LLC Litigation	May 12, 2020USD ($)	Apr. 08, 2016USD ($)	Mar. 31, 2013	Nov. 30, 2012USD ($)	Jun. 30, 2012USD ($)
Damages claimed		$ 500,000
Equity claim	$ 47,420
Proceeds from related party debt				$ 200,000	$ 100,000
Reverse split ratio			0.01
Minimum
Estimate of possible loss		1,500,000
Commercial paper
Face amount		$ 200,000
Solomon Capital, LLC
Debt instrument, convertible, number of equity instruments		1,110

LEASES - Additional information

LEASES - Additional information (Details)

Feb. 08, 2021USD ($)ft²

Aug. 01, 2020USD ($)ft²

Jun. 19, 2019USD ($)ft²

May 28, 2019USD ($)ft²

Oct. 19, 2018USD ($)ft²

Jul. 31, 2017USD ($)

Sep. 30, 2016USD ($)ft²

Aug. 04, 2016USD ($)ft²

Dec. 31, 2014ft²

Sep. 30, 2021USD ($)

Sep. 30, 2020USD ($)

Jan. 31, 2021USD ($)

Oct. 31, 2020USD ($)

Jul. 31, 2020USD ($)

Apr. 30, 2020USD ($)

Sep. 30, 2021USD ($)

Sep. 30, 2020USD ($)

Jan. 31, 2020USD ($)

Jul. 31, 2019USD ($)

Jan. 31, 2019USD ($)

Sep. 01, 2021USD ($)

Dec. 31, 2020USD ($)

Oct. 07, 2020

Jun. 30, 2020USD ($)ft²

Dec. 31, 2019USD ($)

May 02, 2019USD ($)ft²

Jul. 31, 2018USD ($)

Apr. 30, 2015ft²

Term of contract in years

12 months

12 months

Monthly lease payments

$ 137,434,000

$ 137,434,000

First year

9,492,000

9,492,000

Second year

8,006,000

8,006,000

Monthly lease payments

3,605,000

$ 1,893,000

8,439,000

$ 5,995,000

Operating lease liabilities

71,345,000

71,345,000

$ 51,659,000

Operating lease right-of-use assets

72,423,000

72,423,000

$ 54,756,000

Tampa, Florida

Term of contract in years

5 years

Philadelphia, Pennsylvania

Term of contract in years

12 months

Operating expenses

$ 6,500

Area of land | ft²

2,965

Facility leases

Monthly lease payments

131,193,000

131,193,000

First year

5,401,000

5,401,000

Second year

8,006,000

8,006,000

Operating lease liabilities

65,285,000

65,285,000

Facility leases | Tampa, Florida

Option to extend

option to extend

Renewal term in years

5 years

Monthly lease payments

$ 34,500

$ 20,500

Operating expenses

$ 20,000

Area of land | ft²

8,673

5,115

13,139

6,043

Facility leases | San Carlos, California

Additional space of lease | ft²

8,110

First year

$ 39,000

Second year

$ 40,000

Facility leases | New York

Operating expenses

$ 4,000

$ 4,000

$ 4,000

$ 4,000

$ 4,000

$ 4,000

Facility leases | Office Space | San Carlos, California

Monthly lease payments

$ 38,000

Lease Expiration Term

54 months

Monthly lease payments

$ 59,000

Area of land | ft²

20,432

12,322

8,733

Basis spread on operating lease (as a percent)

3.00%

Facility leases | Office Space | New York

Monthly lease payments

$ 9,000

Monthly rental expenses

$ 18,000

Operating expenses

$ 7,000

Office lease for first year | Office Space | Philadelphia, Pennsylvania

Monthly lease payments

$ 2,000

Area of land | ft²

1,500

Office lease for next three years | Philadelphia, Pennsylvania

Basis spread on operating lease (as a percent)

2.50%

Office lease for next three years | Office Space | Philadelphia, Pennsylvania

Term of contract in years

3 years

Monthly lease payments

$ 11,063

Area of land | ft²

4,500

Office lease extended upto July 2025 | Office Space | Philadelphia, Pennsylvania

Renewal term in years

3 years

Monthly lease payments

$ 11,900

Basis spread on operating lease (as a percent)

2.50%

Commercial Manufacturing Facility Agreement

Term of contract in years

359 months

359 months

Option to extend

option to extend

Monthly lease payments

$ 320,000

Prior written notice period (in months)

18 months

Minimum annual increase in basis spread on variable rate (as a percent)

2.00%

Maximum annual increase in basis spread on variable rate (as a percent)

75.00%

Operating expenses

$ 72,000

Operating lease liabilities

41,300,000

Operating lease right-of-use assets

$ 45,700,000

Basis spread on operating lease (as a percent)

0.02%

Commercial Manufacturing Facility Agreement | Office Space

Lease improvements in the commercial manufacturing facility

62,300,000

62,300,000

Area of land | ft²

136,000

Suite 100 and Suit 125 Second Amendment | San Carlos, California

Option to extend

option to extend

Suite 100 and Suit 125 Second Amendment | Office Space | San Carlos, California

Monthly lease payments

$ 103,000

Suite 100 and Suit 125 Second Amendment | Office Space | San Carlos, California | Minimum

Renewal term in years

1 month

Suite 100 and Suit 125 Second Amendment | Office Space | San Carlos, California | Maximum

Renewal term in years

9 months

Extended agreement under Suite 100 And Suit 125 First Amendment | Office Space | San Carlos, California

Monthly lease payments

$ 106,300

Suite 150 First Amendment | San Carlos, California

Option to extend

option to extend

Suite 150 First Amendment | Office Space | San Carlos, California

Monthly lease payments

$ 44,000

Suite 150 First Amendment | Office Space | San Carlos, California | Minimum

Renewal term in years

1 month

Suite 150 First Amendment | Office Space | San Carlos, California | Maximum

Renewal term in years

9 months

Extended agreement under Suite 150 First Amendment | Office Space | San Carlos, California

Monthly lease payments

$ 46,000

New Headquarters Lease

Operating lease liabilities

16,700,000

16,700,000

Operating lease right-of-use assets

$ 17,000,000

17,000,000

New Headquarters Lease | Office Space

Renewal terms in months

60 months

New Headquarters Lease | Office Space | San Carlos, California

Term of contract in years

120 months

Renewal term in years

5 years

Monthly lease payments

$ 280,000

Future minimum rental payments excluding one-time option to extend

$ 36,500,000

Tenant improvement allowance

$ 8,200,000

Area of land | ft²

49,918

Basis spread on operating lease (as a percent)

3.00%

LEASES - Company's right-of-use

LEASES - Company's right-of-use asset and lease liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
LEASES
Operating lease right-of-use assets	$ 72,423	$ 54,756
Operating lease liabilities
Current portion included in current liabilities	6,616	6,284
Long-term portion included in non-current liabilities	64,729	45,375
Total operating lease liabilities	$ 71,345	$ 51,659

LEASES - Components of lease ex

LEASES - Components of lease expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
LEASES
Operating lease cost	$ 4,053	$ 1,652	$ 10,831	$ 5,361
Variable lease cost	1,484	1,702	3,772	4,333
Short-term lease cost	26	26	101	57
Total lease cost	5,563	3,380	14,704	9,751
Cash paid for amounts included in the measurement of lease liabilities included in operating cashflows	3,605	1,893	8,439	5,995
Right-of-use assets obtained from entering new leases	16,999	4,667	17,617	4,667
Increase in right-of-use assets from lease modifications	$ 5,853	$ 206	$ 7,796	$ 534
Weighted-average remaining lease terms (years)	15 years 3 months	1 year 8 months 15 days	15 years 3 months	1 year 8 months 15 days
Weighted-average discount rates	7.20%	7.50%	7.20%	7.50%

LEASES - Maturities of the Comp

LEASES - Maturities of the Company's operating lease liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Remainder of 2021	$ 3,692
2022	9,492
2023	8,006
2024	8,206
2025	8,107
Thereafter	99,931
Total lease payments	137,434
Less: Present value adjustment	(66,089)
Operating lease liabilities	71,345	$ 51,659
Facility leases
Remainder of 2021	1,542
2022	5,401
2023	8,006
2024	8,206
2025	8,107
Thereafter	99,931
Total lease payments	131,193
Less: Present value adjustment	(65,908)
Operating lease liabilities	65,285
CMO embedded leases
Remainder of 2021	2,150
2022	4,091
Total lease payments	6,241
Less: Present value adjustment	(181)
Operating lease liabilities	$ 6,060

LONG-TERM NOTE PAYABLE (Details

LONG-TERM NOTE PAYABLE (Details) - Job Creation Loan	Jan. 26, 2021USD ($)
Debt Instrument [Line Items]
Principal amount	$ 1,000,000
Loan term	5 years
Interest rate (as percent)	0.00%
Lender amount	$ 2,000
Average salary	$ 80,000
Average number of term	5 years

RELATED PARTY TRANSACTIONS - Ad

RELATED PARTY TRANSACTIONS - Additional information (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	Sep. 14, 2017	Sep. 14, 2017	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
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).
Stock-based compensation expense					$ 50,661	$ 30,655
Consulting Agreement
Stock-based compensation expense			$ 0	$ 0	$ 0	$ 200
Board of Directors Chairman
Term of consulting agreement (in years)		3 years
Shares authorized	150	150
Exercise price	$ 7.30
Vesting period		3 years

INCOME TAXES - (Details)

INCOME TAXES - (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
INCOME TAXES
Effective tax rate	0.00%	0.00%	0.00%	0.00%