Bellicum Pharmaceuticals (BLCM) 10-Q 14 Nov 23 2023 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2023	Nov. 09, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2023
Document Transition Report	false
Entity File Number	001-36783
Entity Registrant Name	BELLICUM PHARMACEUTICALS, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-1450200
Entity Address, Address Line One	3730 Kirby Drive,
Entity Address, Address Line Two	Suite 1200,
Entity Address, City or Town	Houston,
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	77098
City Area Code	281
Local Phone Number	454-3424
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		9,716,931
Entity Central Index Key	0001358403
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 5,909	$ 21,837
Accounts receivable, interest and other receivables	15	0
Prepaid expenses and other current assets	924	1,964
Total current assets	6,848	23,801
Property and equipment, net	5	22
Total assets	6,853	23,823
Current liabilities:
Accounts payable	526	486
Accrued expenses and other current liabilities	1,205	2,477
Warrant derivative liability	518	809
Total liabilities	2,249	3,772
Commitments and contingencies
Redeemable preferred stock: $0.01 par value; 10,000,000 shares authorized. Series 1 redeemable convertible preferred stock, $0.01 par value; 1,517,500 shares authorized at September 30, 2023 and December 31, 2022; 452,000 shares issued and outstanding at September 30, 2023 and December 31, 2022	31,618	18,036
Stockholders’ (deficit) equity:
Common stock, $0.01 par value; 160,000,000 shares authorized at September 30, 2023 and December 31, 2022; 9,784,677 shares issued and 9,716,931 shares outstanding at September 30, 2023; 8,682,447 shares issued and 8,614,701 shares outstanding at December 31, 2022	98	87
Treasury stock: 67,746 shares held at September 30, 2023 and December 31, 2022	(5,056)	(5,056)
Additional paid-in capital	569,904	582,763
Accumulated other comprehensive loss	(354)	(354)
Accumulated deficit	(591,606)	(575,425)
Total stockholders’ (deficit) equity	(27,014)	2,015
Total liabilities, redeemable preferred stock and stockholders’ equity	$ 6,853	$ 23,823

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2023	Dec. 31, 2022
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	160,000,000	160,000,000
Common stock, issued (in shares)	9,784,677	8,682,447
Common stock, outstanding (in shares)	9,716,931	8,614,701
Treasury stock, shares (in shares)	67,746	67,746
Convertible Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, authorized (in shares)	1,517,500	1,517,500
Preferred stock, shares issued (in shares)	452,000	452,000
Preferred stock, outstanding (in shares)	452,000	452,000

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenues
Revenues	$ 1,000,000	$ 1,000,000	$ 1,008,000	$ 1,000,000
Operating expenses
Research and development	263,000	6,850,000	12,286,000	16,425,000
General and administrative	1,511,000	1,315,000	5,208,000	4,216,000
Total operating expenses	1,774,000	8,165,000	17,494,000	20,641,000
Other operating expense (income)
Gain on disposal of fixed assets, net	(1,000)	0	(1,000)	0
Total other operating income	(1,000)	0	(1,000)	0
Loss from operations	(773,000)	(7,165,000)	(16,485,000)	(19,641,000)
Other income (expense):
Interest income	2,000	11,000	10,000	38,000
Change in fair value of warrant derivative liability	5,000	(59,000)	291,000	827,000
Other income	3,000	0	3,000	0
Total other income (expense)	10,000	(48,000)	304,000	865,000
Net loss	(763,000)	(7,213,000)	(16,181,000)	(18,776,000)
Net loss attributable to common stockholders	(763,000)	(7,213,000)	(16,181,000)	(18,776,000)
Net loss attributable to common stockholders	$ (763,000)	$ (7,213,000)	$ (16,181,000)	$ (18,776,000)
Net loss per common share attributable to common stockholders, basic (in dollars per share)	$ (0.02)	$ (0.23)	$ (0.52)	$ (0.61)
Net loss per common share attributable to common stockholders, diluted (in dollars per share)	$ (0.02)	$ (0.23)	$ (0.52)	$ (0.61)
Weighted-average shares outstanding, basic (in shares)	30,904,808	30,831,161	30,858,466	30,826,683
Weighted-average shares outstanding, diluted (in shares)	30,904,808	30,831,161	30,858,466	30,826,683
Net loss	$ (763,000)	$ (7,213,000)	$ (16,181,000)	$ (18,776,000)
Other comprehensive loss:
Foreign currency translation adjustment	0	(10,000)	0	(15,000)
Comprehensive loss	(763,000)	(7,223,000)	(16,181,000)	(18,791,000)
Supply agreement
Revenues
Revenues	0	0	8,000	0
License revenue
Revenues
Revenues	$ 1,000,000	$ 1,000,000	$ 1,000,000	$ 1,000,000

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders’ (Deficit) Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Series 1 Preferred	Series 1 Preferred Series 1 Preferred
Preferred stock, beginning balance (in shares) at Dec. 31, 2021								452,000
Preferred stock, beginning balance at Dec. 31, 2021								$ 18,036
Preferred stock, ending balance (in shares) at Mar. 31, 2022								452,000
Preferred stock, ending balance at Mar. 31, 2022								$ 18,036
Balance, beginning of period (in shares) at Dec. 31, 2021		8,497,025	67,746
Balance, beginning of period at Dec. 31, 2021	$ 24,395	$ 85	$ (5,056)	$ 580,156	$ (550,452)	$ (338)
Increase (Decrease) in Stockholders' Equity
Share-based compensation	599			599
Issuance of common stock upon vesting of restricted stock units (in shares)		122,928
Issuance of common stock upon vesting of restricted stock units	0	$ 1		(1)
Issuance of common stock upon exercise of pre-funded warrants (in shares)		56,950
Issuance of common stock upon exercise of pre-funded warrants	0	$ 1		(1)
Comprehensive (loss) income	(7,565)				(7,562)	(3)
Balance, end of period (in shares) at Mar. 31, 2022		8,676,903	67,746
Balance, end of period at Mar. 31, 2022	17,429	$ 87	$ (5,056)	580,753	(558,014)	(341)
Preferred stock, beginning balance (in shares) at Dec. 31, 2021								452,000
Preferred stock, beginning balance at Dec. 31, 2021								$ 18,036
Preferred stock, ending balance (in shares) at Sep. 30, 2022							452,000
Preferred stock, ending balance at Sep. 30, 2022							$ 18,036
Balance, beginning of period (in shares) at Dec. 31, 2021		8,497,025	67,746
Balance, beginning of period at Dec. 31, 2021	24,395	$ 85	$ (5,056)	580,156	(550,452)	(338)
Increase (Decrease) in Stockholders' Equity
Comprehensive (loss) income	(18,791)
Balance, end of period (in shares) at Sep. 30, 2022		8,680,687	67,746
Balance, end of period at Sep. 30, 2022	7,499	$ 87	$ (5,056)	582,049	(569,228)	(353)
Preferred stock, beginning balance (in shares) at Mar. 31, 2022								452,000
Preferred stock, beginning balance at Mar. 31, 2022								$ 18,036
Preferred stock, ending balance (in shares) at Jun. 30, 2022								452,000
Preferred stock, ending balance at Jun. 30, 2022								$ 18,036
Balance, beginning of period (in shares) at Mar. 31, 2022		8,676,903	67,746
Balance, beginning of period at Mar. 31, 2022	17,429	$ 87	$ (5,056)	580,753	(558,014)	(341)
Increase (Decrease) in Stockholders' Equity
Share-based compensation	611			611
Issuance of common stock upon vesting of restricted stock units (in shares)		2,116
Comprehensive (loss) income	(4,003)				(4,001)	(2)
Balance, end of period (in shares) at Jun. 30, 2022		8,679,019	67,746
Balance, end of period at Jun. 30, 2022	14,037	$ 87	$ (5,056)	581,364	(562,015)	(343)
Preferred stock, ending balance (in shares) at Sep. 30, 2022							452,000
Preferred stock, ending balance at Sep. 30, 2022							$ 18,036
Increase (Decrease) in Stockholders' Equity
Share-based compensation	685			685
Issuance of common stock upon vesting of restricted stock units (in shares)		1,668
Comprehensive (loss) income	(7,223)				(7,213)	(10)
Balance, end of period (in shares) at Sep. 30, 2022		8,680,687	67,746
Balance, end of period at Sep. 30, 2022	7,499	$ 87	$ (5,056)	582,049	(569,228)	(353)
Preferred stock, beginning balance (in shares) at Dec. 31, 2022								452,000
Preferred stock, beginning balance at Dec. 31, 2022	18,036							$ 18,036
Increase (Decrease) in Temporary Equity [Roll Forward]
Accretion of Series 1 preferred stock redemption	$ 4,528			4,528				$ 4,528
Preferred stock, ending balance (in shares) at Mar. 31, 2023								452,000
Preferred stock, ending balance at Mar. 31, 2023								$ 22,564
Balance, beginning of period (in shares) at Dec. 31, 2022	8,614,701	8,682,447	67,746
Balance, beginning of period at Dec. 31, 2022	$ 2,015	$ 87	$ (5,056)	582,763	(575,425)	(354)
Increase (Decrease) in Stockholders' Equity
Share-based compensation	559			559
Issuance of common stock upon vesting of restricted stock units (in shares)		1,597
Issuance of common stock upon vesting of restricted stock units	0
Issuance of common stock upon exercise of pre-funded warrants (in shares)		430,000
Issuance of common stock upon exercise of pre-funded warrants	0	$ 4		(4)
Accretion of Series 1 preferred stock redemption	(4,528)			(4,528)				$ (4,528)
Comprehensive (loss) income	(8,066)				(8,066)
Balance, end of period (in shares) at Mar. 31, 2023		9,114,044	67,746
Balance, end of period at Mar. 31, 2023	(10,020)	$ 91	$ (5,056)	578,790	(583,491)	(354)
Preferred stock, beginning balance (in shares) at Dec. 31, 2022								452,000
Preferred stock, beginning balance at Dec. 31, 2022	18,036							$ 18,036
Preferred stock, ending balance (in shares) at Sep. 30, 2023								452,000
Preferred stock, ending balance at Sep. 30, 2023	$ 31,618						31,600	$ 31,618
Balance, beginning of period (in shares) at Dec. 31, 2022	8,614,701	8,682,447	67,746
Balance, beginning of period at Dec. 31, 2022	$ 2,015	$ 87	$ (5,056)	582,763	(575,425)	(354)
Increase (Decrease) in Stockholders' Equity
Comprehensive (loss) income	$ (16,181)
Balance, end of period (in shares) at Sep. 30, 2023	9,716,931	9,784,677	67,746
Balance, end of period at Sep. 30, 2023	$ (27,014)	$ 98	$ (5,056)	569,904	(591,606)	(354)
Preferred stock, beginning balance (in shares) at Mar. 31, 2023								452,000
Preferred stock, beginning balance at Mar. 31, 2023								$ 22,564
Increase (Decrease) in Temporary Equity [Roll Forward]
Accretion of Series 1 preferred stock redemption	4,527			4,527				$ 4,527
Preferred stock, ending balance (in shares) at Jun. 30, 2023								452,000
Preferred stock, ending balance at Jun. 30, 2023								$ 27,091
Balance, beginning of period (in shares) at Mar. 31, 2023		9,114,044	67,746
Balance, beginning of period at Mar. 31, 2023	(10,020)	$ 91	$ (5,056)	578,790	(583,491)	(354)
Increase (Decrease) in Stockholders' Equity
Share-based compensation	59			59
Issuance of common stock upon exercise of pre-funded warrants (in shares)		450,000
Issuance of common stock upon exercise of pre-funded warrants	0	$ 5		(5)
Accretion of Series 1 preferred stock redemption	(4,527)			(4,527)				(4,527)
Comprehensive (loss) income	(7,352)				(7,352)
Balance, end of period (in shares) at Jun. 30, 2023		9,564,044	67,746
Balance, end of period at Jun. 30, 2023	(21,840)	$ 96	$ (5,056)	574,317	(590,843)	(354)
Increase (Decrease) in Temporary Equity [Roll Forward]
Accretion of Series 1 preferred stock redemption	4,527			4,527				$ 4,527
Preferred stock, ending balance (in shares) at Sep. 30, 2023								452,000
Preferred stock, ending balance at Sep. 30, 2023	31,618						$ 31,600	$ 31,618
Increase (Decrease) in Stockholders' Equity
Share-based compensation	116			116
Issuance of common stock upon vesting of restricted stock units (in shares)		220,633
Issuance of common stock upon vesting of restricted stock units		$ 2		(2)
Accretion of Series 1 preferred stock redemption	(4,527)			(4,527)				$ (4,527)
Comprehensive (loss) income	$ (763)				(763)	0
Balance, end of period (in shares) at Sep. 30, 2023	9,716,931	9,784,677	67,746
Balance, end of period at Sep. 30, 2023	$ (27,014)	$ 98	$ (5,056)	$ 569,904	$ (591,606)	$ (354)

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Cash flows from operating activities:
Net loss	$ (763)	$ (7,213)	$ (16,181)	$ (18,776)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation			734	1,895
Depreciation and amortization expense			7	9
Gain on disposal of fixed assets, net	(1)	0	(1)	0
Change in fair value of warrant derivative liability	(5)	59	(291)	(827)
Changes in operating assets and liabilities:
Accounts receivable, interest and other receivables			(15)	(795)
Prepaid expenses and other assets			1,040	(241)
Accounts payable			40	624
Accrued liabilities and other			(1,272)	(761)
Net cash used in operating activities			(15,939)	(18,872)
Cash flows from investing activities:
Purchases of property and equipment			(4)	(14)
Proceeds from sale of fixed Asset			15	0
Net cash provided by (used in) investing activities			11	(14)
Effect of exchange rate changes on cash			0	(15)
Net change in cash, cash equivalents, and restricted cash			(15,928)	(18,901)
Cash, cash equivalents and restricted cash at beginning of period			21,837	47,657
Cash, cash equivalents and restricted cash at end of period	$ 5,909	$ 28,756	$ 5,909	$ 28,756

ORGANIZATION, BASIS OF PRESENTA

ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Organization Bellicum Pharmaceuticals, Inc. (“Bellicum”) is a clinical stage biopharmaceutical company that has discovered and developed novel, controllable cellular immunotherapies for various forms of cancer, including both hematological cancers and solid tumors. As of September 30, 2023, Bellicum has one wholly-owned subsidiary, Bellicum Pharma GmbH, a private limited liability company organized under German law. It was formed for the purpose of developing product candidates in Europe. Bellicum and Bellicum Pharma GmbH are collectively referred to herein as the “Company.” All intercompany balances and transactions among the consolidated entities have been eliminated in consolidation. Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in conformity with the authoritative U.S. generally accepted accounting principles (“GAAP”) for interim financial information and pursuant to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission (“SEC”). Accordingly, the accompanying unaudited condensed consolidated financial statements do not include all of the information and notes required by GAAP for complete financial statements. The unaudited interim financial statements reflect all adjustments which, in the opinion of management, are necessary for a fair statement of the results for the periods presented. All such adjustments are of a normal and recurring nature. The operating results presented in these unaudited condensed consolidated financial statements are not necessarily indicative of the results that may be expected for any future periods. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto in the Company’s Annual Report on Form 10-K (“Annual Report”) for the fiscal year ended December 31, 2022, as filed with the SEC on March 31, 2023. The Company has experienced net losses from operations since its inception and as of September 30, 2023 and December 31, 2022, the Company had an accumulated defic it of $591.6 million and $575.4 million, respectively, and at September 30, 2023, the Company had cash and cash equivalents of approximately $5.9 million. The Company believes that there is substantial doubt that its current capital resources, which consist of cash and cash equivalents, are sufficient to fund operations through at least the next twelve months from the date the accompanying financial statements are issued. The accompanying financial statements have been prepared on a basis that assumes that the Company will continue as a going concern, and do not include any adjustments that may result from the outcome of this uncertainty. This basis of accounting contemplates the recovery of the Company’s assets and the satisfaction of the Company’s liabilities and commitments in the normal course of business and does not include any adjustments to reflect the possible future effects of the recoverability and classification of recorded asset amounts or amounts and classification of liabilities that might be necessary should the Company be unable to continue as a going concern. In March 2023, the Company announced its decision to discontinue its ongoing Phase 1/2 clinical trials evaluating the safety and preliminary efficacy of its GoCAR-T cell product candidates in combination with rimiducid in heavily pre-treated cancer patients. The trials for BPX-601 and BPX-603 are being discontinued following the Company’s assessment of the risk/benefit profile of BPX-601 in combination with rimiducid. An evaluation of the Company’s strategic alternatives is underway. The strategic alternatives include, but are not limited to, a merger, sale, or other business combination, a strategic partnership with one or more parties, or the licensing, sale, or divestiture of our programs. Despite undertaking this process, the Company may not be successful in completing a transaction, and even if a strategic transaction is completed, it ultimately may not deliver the anticipated benefits. If the Company does not successfully consummate a strategic alternative, its board of directors may decide to pursue a dissolution and liquidation of the Company. Even if the Company is successful in consummating one or more such strategic alternatives, it may cease operations as a result and its board or directors may choose to dissolve the Company and distribute the proceeds of such strategic alternative, if any, and any remaining assets to its stockholders. Use of Estimates The preparation of the interim condensed consolidated financial statements in accordance with GAAP requires management to make certain estimates and judgments that affect the reported amounts of assets, liabilities, and expenses. Actual results could differ from those estimates. Revenue Recognition The Company's sources of revenue during the nine months ended September 30, 2023 include the sale of a proprietary reagent to a third party, which resulted in recognized revenue of $8.0 thousand during the first quarter of 2023. Additionally, in the third quarter of 2023, the Company received an annual maintenance fee of $1.0 million as specified in the 2021 MD Anderson Option and License Agreement executed in August 2021. Significant Accounting Policies There have been no significant changes to the accounting policies during the nine months ended September 30, 2023, as compared to the significant accounting policies described in Note 1 of the “Notes to Consolidated Financial Statements” in the Company’s audited financial statements included in its Annual Report on Form 10-K for the fiscal year ended December 31, 2022. Accrued Expenses and Other Current Liabilities Accrued expenses and other liabilities consist of the following: (in thousands) September 30, 2023 December 31, 2022 Accrued payroll $ 89 $ 264 Accrued patient treatment costs 2 675 Accrued clinical research costs 494 841 Accrued manufacturing costs 105 434 Accrued professional services 373 207 Accrued other 142 56 Total accrued expenses and other current liabilities $ 1,205 $ 2,477 Net (Loss) Income and Net (Loss) Income per Share of Common Stock Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period without consideration for common stock equivalents. Diluted earnings per share is based on the more dilutive method between the two-class method and the treasury stock method and includes the effect from potential issuance of ordinary shares, such as shares issuable pursuant to the conversion of preferred stock to common stock, exercise of warrants to purchase common stock, exercise of stock options, and vesting of restricted stock units. For periods of net loss, diluted net loss per share is calculated similarly to basic net loss per share. The following outstanding shares of common stock equivalents were excluded from the computations of diluted loss per share of common stock attributable to common stockholders for the periods presented as the effect of including such securities would be anti-dilutive. September 30, 2023 September 30, 2022 Anti-dilutive common stock equivalents: Number of Shares Redeemable convertible series 1 preferred stock 4,520,000 4,520,000 Warrants to purchase common stock 5,750,000 5,750,000 Options to purchase common stock 215,206 3,658,489 Unvested shares of restricted stock units 397,987 225,633 Total anti-dilutive common stock equivalents 10,883,193 14,154,122

FAIR VALUE MEASUREMENTS AND INV

FAIR VALUE MEASUREMENTS AND INVESTMENT SECURITIES	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS AND INVESTMENT SECURITIES	FAI R VALU E MEASUREMENTS AND INVESTMENT SECURITIES Fair Value of Financial Instruments Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a fair value hierarchy has been established that prioritizes the inputs used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurement) and the lowest priority to unobservable inputs (Level 3 measurement). These inputs are classified into the following hierarchy: Level 1 Inputs - quoted prices (unadjusted) for identical assets in active markets that the reporting entity has the ability to access at the measurement date; Level 2 Inputs - inputs other than quoted prices included within Level 1 that are observable for the asset, either directly or indirectly; and Level 3 Inputs - unobservable inputs for the assets. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company believes the recorded values of its financial instruments, including cash and cash equivalents, accounts payable, and accrued liabilities approximate their fair values due to the short-term nature of these instruments. Investment Securities The following table presents the Company’s investment securities (including, if applicable, those classified on the Company’s balance sheet as cash equivalents) that are measured at fair value on a recurring basis as of September 30, 2023 and December 31, 2022: Fair Value at September 30, 2023 Fair Value at December 31, 2022 (in thousands) Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Cash equivalents: Money market funds $ 4,532 $ — $ — $ 20,024 $ — $ — Total cash equivalents $ 4,532 $ — $ — $ 20,024 $ — $ — Money market funds are valued based on various observable inputs such as benchmark yields, reported trades, broker/dealer quotes, benchmark securities and bids. Warrant Derivative Liability The Company’s financial liabilities recorded at fair value on a recurring basis include the fair values of the warrant derivative liability. The Company estimates the fair value (Level 3) of the warrants using the Black-Scholes valuation technique, which utilizes assumptions including (i) the fair value of the underlying stock relative to the warrant exercise price at the valuation measurement date, (ii) volatility of the price of the underlying stock, (iii) the expected term of the warrants, and (iv) risk-free interest rates. The fair value of the warrant derivative liability is classified as current liability in the accompanying condensed consolidated balance sheets. This liability is classified as current liability on the balance sheet because the exercisability of such warrants is outside of the Company’s control, and the Company does not have the unconditional right to defer settlement beyond 12 months. The fair value of the warrants has been estimated with the following weighted-average assumptions, including the most sensitive input, volatility: September 30, 2023 December 31, 2022 Risk-free interest rate 4.80% 4.1% Volatility 143.00% 102.00% Expected term (years) 2.88 3.63 The following table provides the warrant derivative liability reported at fair value and measured on a recurring basis: Fair Value at September 30, 2023 Fair Value at December 31, 2022 (in thousands) Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Warrant derivative liability $ — $ — $ 518 $ — $ — $ 809 The ending balance of the Level 3 financial instruments presented above represents the Company’s best estimate of valuation and may not be substantiated by comparison to independent markets and, in many cases, could not be realized in immediate settlement of the instruments.

PUBLIC OFFERING AND PRIVATE PLA

PUBLIC OFFERING AND PRIVATE PLACEMENT	9 Months Ended
	Sep. 30, 2023
Statement of Stockholders' Equity [Abstract]
PUBLIC OFFERING AND PRIVATE PLACEMENT	PUBLIC OFFERING AND PRIVATE PLACEMENT December 2021 Private Placement On December 4, 2021, the Company entered into a Securities Purchase Agreement (the “2021 Securities Purchase Agreement”) with certain institutional investors, pursuant to which the Company issued pre-funded warrants to purchase an aggregate of 20,559,210 shares of its common stock and accompanying common warrants to purchase an aggregate of 2,055,920 shares of its common stock. Each pre-funded warrant to purchase one share of common stock was sold together with one warrant to purchase one-tenth of one share of common stock at a combined unit price of $1.7024. The pre-funded warrants were immediately exercisable at an exercise price of $0.0001 per share of common stock. The accompanying common warrants were immediately exercisable at an exercise price of $1.69 per share of common stock and will expire seven years from the date of issuance. The gross proceeds to the Company from the private placement were approximately $35.0 million before deducting placement agent commissions and offering expenses payable by the Company, excluding any proceeds that may be received upon exercise of the accompanying warrants. In addition, pursuant to the 2021 Securities Purchase Agreement, certain purchasers who entered into the 2019 Securities Purchase Agreement (defined below) irrevocably waived the right to cause the Company to conduct the “First Closing” and “Second Closing” (each term as defined in the 2019 Securities Purchase Agreement) under the 2019 Securities Purchase Agreement, which releases the Company of potential cash or equity obligations. November 2020 Underwritten Offering On November 2, 2020, the Company closed an underwritten offering of 1,040,000 shares of its common stock, pre-funded warrants to purchase 3,109,378 shares of its common stock, and accompanying common warrants to purchase up to an aggregate of 4,149,378 shares of its common stock. Each share of common stock and pre-funded warrant to purchase one share of common stock was sold together with a common warrant to purchase one share of common stock. The public offering price of each share of common stock and accompanying common warrant was $6.025 and $6.024 for each pre-funded warrant. The pre-funded warrants were immediately exercisable at a price of $0.001 per share of common stock. The common warrants were immediately exercisable at an exercise price of $6.50 per share of common stock and will expire five years from the date of issuance. The shares of common stock and pre-funded warrants, and the accompanying common warrants, were issued separately and were immediately separable upon issuance. The gross proceeds to the Company were approximately $25.0 million before deducting underwriting discounts and commissions and other offering expenses. August 2019 Public Offering On August 16, 2019, the Company entered into an underwriting agreement (the “Underwriting Agreement”) with Jefferies LLC and Wells Fargo Securities, LLC, as representatives of the several underwriters named therein (the “Underwriters”), relating to an underwritten public offering (the “Offering”) of 575,000 shares of the Series 1 Redeemable Convertible Non-Voting Preferred Stock of the Company (the “Series 1 Preferred Stock”) and warrants (the “Public Warrants”) to purchase up to 5,750,000 shares of its common stock. Each share of Series 1 Preferred Stock was being sold together with a warrant to purchase 10 shares of common stock at a combined price to the public of $100.00. Under certain circumstances, each warrant to purchase 10 shares of common stock will be exercisable, at the irrevocable election of the holder, for one share of Series 1 Preferred Stock. The offering closed on August 21, 2019, and the net proceeds to the Company from the Offering were approximately $53.8 million after deducting underwriting discounts and commissions and estimated offering expenses payable by the Company, and excluding any proceeds that the Company may receive upon exercise of the Public Warrants. All of the Public Warrants sold in the Offering have an exercise price of $13.00 per share of common stock or, in certain circumstances, for $130.00 per share of Series 1 Preferred Stock, subject to proportional adjustments in the event of stock splits or combinations or similar events. The Public Warrants were immediately exercisable upon issuance, provided that the holder is prohibited, subject to certain exceptions, from exercising a warrant for shares of common stock to the extent that immediately prior to or after giving effect to such exercise, the holder, together with its affiliates and other attribution parties, would own more than 9.99% of the total number of shares of common stock then issued and outstanding, which percentage may be changed at the holder’s election to a lower percentage at any time or to a higher percentage not to exceed 19.99% upon 61 days’ notice to the Company. The Public Warrants will expire on August 21, 2026, unless exercised prior to that date. The following table reflects the fair value roll forward reconciliation of the Public Warrants liabilities for the period ended September 30, 2023: (in thousands) Warrant Derivative Liability Balance, December 31, 2022 $ 809 Change in fair value (291) Balance, September 30, 2023 $ 518 Private Placement On August 16, 2019, the Company entered into a Securities Purchase Agreement (the “Securities Purchase Agreement”) with certain institutional investors named therein (the “Purchasers”), pursuant to which the Company agreed to issue in a private placement (i) 350,000 shares of its Series 2 Redeemable Convertible Non-Voting Preferred Stock (the “Series 2 Preferred Stock”), at a purchase price of $100.00 per share, and related warrants (the “Private Warrants”) to purchase up to 2,800,000 shares of common stock at an exercise price of $10.00 per share, and (ii) 250,000 shares of its Series 3 Redeemable Convertible Non-Voting Preferred Stock (the “Series 3 Preferred Stock” and, together with the Series 1 Preferred Stock and Series 2 Preferred Stock, the “Preferred Stock”), at a purchase price of $140.00 per share, and related warrants (also, “Private Warrants”) to purchase up to 875,000 shares of common stock at an exercise price of $14.00 per share. The Company received $11.2 million in net option fee proceeds, net of offering costs, upon the execution of the 2019 Securities Purchase Agreement. Pursuant to the 2021 Securities Purchase Agreement entered into on December 4, 2021, the Purchasers irrevocably waived the right to purchase such securities, and the Company derecognized the private placement option liability for the year ended December 31, 2021. The Company is no longer obligated to issue the Series 2 Preferred Stock, Series 3 Preferred Stock, or any associated Private Warrants. A summary of warrants outstanding and exercisable as of September 30, 2023 is as follows: Year Issued Warrants Outstanding and Exercisable Weighted Average Remaining Weighted Average Exercise Price (in years) (per share) 2019 5,750,000 2.88 $ 13.00 2020 4,149,378 2.10 $ 6.50 2020 1 1,659,752 — $ — 2021 2,055,920 5.19 $ 1.69 2021 2 19,679,210 — $ — 33,294,260

REDEEMABLE CONVERTIBLE PREFERRE

REDEEMABLE CONVERTIBLE PREFERRED STOCK	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
REDEEMABLE CONVERTIBLE PREFERRED STOCK	REDEEMABLE CONVERTIBLE PREFERRED STOCKOn August 21, 2019, the Company sold Series 1 Preferred Stock pursuant to the Offering. The Company has 10,000,000 authorized shares of Preferred Stock with a par value of $0.01 per share, of which the Company has designated 1,517,500 shares as Series 1 Preferred Stock, 350,000 shares as Series 2 Preferred Stock and 250,000 shares as Series 3 Preferred Stock. There were 452,000 shares of Series 1 Preferred Stock and no shares of Series 2 or Series 3 Preferred Stock issued and outstanding as of September 30, 2023. The Series 1 Preferred Stock, Series 2 Preferred Stock and Series 3 Preferred Stock is referred to collectively as the Preferred Stock. As of September 30, 2023, the Company classified the Series 1 Preferred Stock as mezzanine equity, because the Series 1 Preferred Stock is redeemable at the option of the holders upon passage of time, which is outside of the Company’s control to prevent. Subsequent adjustment of the amount presented in mezzanine equity to its redemption amount is necessary unless it is probable that the instrument will not become redeemable. The Series 1 Preferred Stock is not redeemable at September 30, 2023, and is only redeemable upon a fundamental change or, at the option of the holder, on or after August 21, 2024, if certain Conditions have not been met (described below) before that date. The “Conditions” mean: (1) the closing price of the Company’s common stock has been equal to or exceeded $25.00 per share for 180 calendar days (for determining if the Conditions are met for the Series 1 Preferred Stock) for 180 calendar days; (2) the 50-day average trading volume of the Company’s common stock on the Nasdaq stock market is greater than 50,000 shares; and (3) a Phase 3 or Phase 2 pivotal clinical trial for one of the Company’s CAR-T product candidates has been initiated, meaning that at least one clinical trial site has been activated. A subsequent adjustment of the amount presented within mezzanine equity to its redemption amount is necessary if it is probable that the instrument will become redeemable. The Company does not believe a fundamental change is considered probable until it occurs. However, as of December 31, 2022, the Company concluded that it was probable that the Conditions will not be met before August 21, 2024. Therefore, the Company will prospectively accrete the Series 1 Preferred Stock to its redemption amount of $45.2 million over the future reporting periods until the earliest redemption date. As of September 30, 2023, the Series 1 Preferred Stock has been remeasured to $31.6 million. Optional Conversion Each share of Preferred Stock is initially convertible into 10 shares of common stock. The conversion price at which Preferred Stock may be converted into shares of common stock, is subject to adjustment in connection with certain specified events. Redemption Until the applicable Transition Date (defined below), at any time on or after August 21, 2024, all or any portion of the Preferred Stock is redeemable at the option of the holder. The redemption price of the Series 1 Preferred Stock, which is the only series of Preferred Stock outstanding, is $100.00 per share. The “Transition Date” means, with respect to the Series 1 Preferred Stock, the first date following August 21, 2021, on which each of the Conditions (as defined above) is met. Dividends Shares of Preferred Stock will be entitled to receive dividends equal to (on an as-if-converted-to-common stock basis), and in the same form and manner as, dividends actually paid on shares of common stock. Liquidation Until the applicable Transition Date, in the event of a liquidation, dissolution, winding up or deemed liquidation, holders of the Preferred Stock will receive a payment equal to the applicable per share purchase price of their Preferred Stock before any proceeds are distributed to the holders of Common Stock. The liquidation preferences, protective voting provisions and redemption rights of the Preferred Stock will terminate upon the occurrence of certain events. Voting Shares of Preferred Stock will generally have no voting rights, except to the extent expressly provided in the Company’s certificate of incorporation or as otherwise required by law.

SHARE-BASED COMPENSATION PLANS

SHARE-BASED COMPENSATION PLANS	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
SHARE-BASED COMPENSATION PLANS	SHARE-BASED COMPENSATION PLANSShare-Based Compensation Plans The Company has five share-based compensation plans, including the 2019 Equity Incentive Plan (the “2019 Plan”), which was adopted in June 2019. Each plan authorizes the granting of shares of common stock and/or options to purchase common stock to employees and directors of the Company, as well as non-employee consultants, and allows the holder of the option to purchase common stock at a stated exercise price. The only plan under which the Company may currently grant equity awards is the 2019 Equity Incentive Plan, although there remain outstanding awards under the other four plans. Options vest according to the terms of the grant, which may be immediately or based on the passage of time, generally over two Share-Based Compensation Expense Share-based compensation expense by classification for the three and nine months ended September 30, 2023 and 2022 are as follows: Three Months Ended Nine Months Ended (in thousands) September 30, 2023 September 30, 2022 September 30, 2023 September 30, 2022 Research and development $ (9) $ 334 $ 96 $ 921 General and administrative 125 351 638 974 Total $ 116 $ 685 $ 734 $ 1,895 At September 30, 2023, total compensation cost not yet recognized was $0.1 million and the weighted-average period over which this amount is expected to be recognized is 0.2 years.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES License Agreement - Baylor In 2008, 2010, 2014 and 2016, the Company and Baylor College of Medicine (“BCM”) entered into license agreements pursuant to which the Company obtained exclusive rights to certain technologies and patent rights owned by BCM. Under the 2014 license agreement, the Company is required to pay BCM a low annual maintenance fee on each anniversary of the agreement date. The Company is also required to make royalty payments in the low single digits, subject to certain annual minimums, on net sales of products covered by the license and, to the extent the Company enters into a sublicensing agreement relating to a licensed product, the Company is also required to pay BCM a percentage in the low double-digits on all non-royalty income received from sublicensing revenue. As the Company has no active efforts or plans to pursue the licensed technologies under two 2016 license agreements, the Company terminated both license agreements effective December 20, 2022. License Agreement - Agensys, Inc. On December 10, 2015, the Company and Agensys, Inc. (“Agensys”), entered into a license agreement (the “Agensys Agreement”), pursuant to which (i) Agensys granted the Company, within the field of cell and gene therapy of diseases in humans, an exclusive, worldwide license and sublicense to its patent rights directed to prostate stem cell antigen 1 (“PSCA”) and related antibodies, and (ii) the Company granted Agensys a non-exclusive, fully paid license to the Company’s patents directed to inventions that were made by the Company in the course of developing the Company’s licensed products, solely for use with Agensys therapeutic products containing a soluble antibody that binds to PSCA or, to the extent not based upon the Company’s other proprietary technology, to non-therapeutic applications of antibodies not used within the field. As consideration for the rights granted to the Company under the Agreement, the Company agreed to pay to Agensys a non-refundable upfront fee of $3.0 million, which was included in license fee expense. The Company is also required to make aggregate milestone payments to Agensys of up to (i) $5.0 million upon the first achievement of certain specified clinical milestones for its licensed products, (ii) $50.0 million upon the achievement of certain specified clinical milestones for each licensed product, and (iii) $75.0 million upon the achievement of certain sales milestones for each licensed product. The Agreement additionally provides that the Company will pay to Agensys a royalty that ranges from the mid to high single digits based on the level of annual net sales of licensed products by the Company, its affiliates or permitted sublicensees. The royalty payments are subject to reduction under specified circumstances. These milestone and royalty payments will be expensed as incurred. Under the Agreement, Agensys also was granted the option to obtain an exclusive license, on a product-by-product basis, from the Company to commercialize in Japan each licensed product developed under the Agensys Agreement that has completed a phase 2 clinical trial. As to each such licensed product, if Agensys or its affiliate, Astellas Pharma, Inc., exercises the option, the Agensys Agreement provides that the Company will be paid an option exercise fee of $5.0 million. In addition, the Agensys Agreement provides that the Company will be paid a royalty that ranges from the mid to high single digits based on the level of annual net sales in Japan of each such licensed product. If the option is exercised, the aggregate milestone payments payable by the Company to Agensys, described above with respect to each licensed product, would be reduced by up to an aggregate of $65.0 million upon the achievement of certain specified clinical and sales milestones. The Agensys Agreement will terminate upon the expiration of the last royalty term for the products covered by the Agensys Agreement, which is the earlier of (i) the date of expiration or abandonment of the last valid claim within the licensed patent rights covering any licensed products under the Agreement, (ii) the expiration of regulatory exclusivity as to a licensed product, and (iii) 10 years after the first commercial sale of a licensed product. Either party may terminate the Agensys Agreement upon a material breach by the other party that remains uncured following 60 days after the date of written notice of such breach (or 30 days if such material breach is related to failure to make payment of amounts due under the Agensys Agreement) or upon certain insolvency events. In addition, Agensys may terminate the Agensys Agreement immediately upon written notice to the Company if the Company or any of its affiliates or permitted sublicensees commences an interference proceeding or challenges the validity or enforceability of any of Agensys’ patent rights. License Agreement - BioVec On June 10, 2015, the Company and BioVec Pharma, Inc. (“BioVec”) entered into a license agreement (the “BioVec Agreement”) pursuant to which BioVec agreed to supply the Company with certain proprietary cell lines and granted to the Company a non-exclusive, worldwide license to certain of its patent rights and related know-how related to such proprietary cell lines. As consideration for the products supplied and rights granted to the Company under the BioVec Agreement, the Company agreed to pay to BioVec an upfront fee of $100,000 within ten ten

ORGANIZATION, BASIS OF PRESEN_2

ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of PresentationThe accompanying unaudited condensed financial statements have been prepared in conformity with the authoritative U.S. generally accepted accounting principles (“GAAP”) for interim financial information and pursuant to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission (“SEC”).
Use of Estimates	Use of Estimates The preparation of the interim condensed consolidated financial statements in accordance with GAAP requires management to make certain estimates and judgments that affect the reported amounts of assets, liabilities, and expenses. Actual results could differ from those estimates.
Net (Loss) Income and Net (Loss) Income per Share of Common Stock Attributable to Common Stockholders	Net (Loss) Income and Net (Loss) Income per Share of Common Stock Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period without consideration for common stock equivalents. Diluted earnings per share is based on the more dilutive method between the two-class method and the treasury stock method and includes the effect from potential issuance of ordinary shares, such as shares issuable pursuant to the conversion of preferred stock to common stock, exercise of warrants to purchase common stock, exercise of stock options, and vesting of restricted stock units. For periods of net loss, diluted net loss per share is calculated similarly to basic net loss per share.
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a fair value hierarchy has been established that prioritizes the inputs used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurement) and the lowest priority to unobservable inputs (Level 3 measurement). These inputs are classified into the following hierarchy: Level 1 Inputs - quoted prices (unadjusted) for identical assets in active markets that the reporting entity has the ability to access at the measurement date; Level 2 Inputs - inputs other than quoted prices included within Level 1 that are observable for the asset, either directly or indirectly; and Level 3 Inputs - unobservable inputs for the assets. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The Company believes the recorded values of its financial instruments, including cash and cash equivalents, accounts payable, and accrued liabilities approximate their fair values due to the short-term nature of these instruments.

ORGANIZATION, BASIS OF PRESEN_3

ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other liabilities consist of the following: (in thousands) September 30, 2023 December 31, 2022 Accrued payroll $ 89 $ 264 Accrued patient treatment costs 2 675 Accrued clinical research costs 494 841 Accrued manufacturing costs 105 434 Accrued professional services 373 207 Accrued other 142 56 Total accrued expenses and other current liabilities $ 1,205 $ 2,477
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following outstanding shares of common stock equivalents were excluded from the computations of diluted loss per share of common stock attributable to common stockholders for the periods presented as the effect of including such securities would be anti-dilutive. September 30, 2023 September 30, 2022 Anti-dilutive common stock equivalents: Number of Shares Redeemable convertible series 1 preferred stock 4,520,000 4,520,000 Warrants to purchase common stock 5,750,000 5,750,000 Options to purchase common stock 215,206 3,658,489 Unvested shares of restricted stock units 397,987 225,633 Total anti-dilutive common stock equivalents 10,883,193 14,154,122

FAIR VALUE MEASUREMENTS AND I_2

FAIR VALUE MEASUREMENTS AND INVESTMENT SECURITIES (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Schedule of Assets Measured at Fair Value on a Recurring Basis	The following table presents the Company’s investment securities (including, if applicable, those classified on the Company’s balance sheet as cash equivalents) that are measured at fair value on a recurring basis as of September 30, 2023 and December 31, 2022: Fair Value at September 30, 2023 Fair Value at December 31, 2022 (in thousands) Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Cash equivalents: Money market funds $ 4,532 $ — $ — $ 20,024 $ — $ — Total cash equivalents $ 4,532 $ — $ — $ 20,024 $ — $ — The following table provides the warrant derivative liability reported at fair value and measured on a recurring basis: Fair Value at September 30, 2023 Fair Value at December 31, 2022 (in thousands) Level 1 Level 2 Level 3 Level 1 Level 2 Level 3 Warrant derivative liability $ — $ — $ 518 $ — $ — $ 809
Schedule of Derivative Liabilities at Fair Value	The fair value of the warrants has been estimated with the following weighted-average assumptions, including the most sensitive input, volatility: September 30, 2023 December 31, 2022 Risk-free interest rate 4.80% 4.1% Volatility 143.00% 102.00% Expected term (years) 2.88 3.63 The following table reflects the fair value roll forward reconciliation of the Public Warrants liabilities for the period ended September 30, 2023: (in thousands) Warrant Derivative Liability Balance, December 31, 2022 $ 809 Change in fair value (291) Balance, September 30, 2023 $ 518

PUBLIC OFFERING AND PRIVATE P_2

PUBLIC OFFERING AND PRIVATE PLACEMENT (Tables)	9 Months Ended
	Sep. 30, 2023
Statement of Stockholders' Equity [Abstract]
Schedule of Derivative Liabilities at Fair Value	The fair value of the warrants has been estimated with the following weighted-average assumptions, including the most sensitive input, volatility: September 30, 2023 December 31, 2022 Risk-free interest rate 4.80% 4.1% Volatility 143.00% 102.00% Expected term (years) 2.88 3.63 The following table reflects the fair value roll forward reconciliation of the Public Warrants liabilities for the period ended September 30, 2023: (in thousands) Warrant Derivative Liability Balance, December 31, 2022 $ 809 Change in fair value (291) Balance, September 30, 2023 $ 518
Schedule of Warrants Outstanding and Exercisable	A summary of warrants outstanding and exercisable as of September 30, 2023 is as follows: Year Issued Warrants Outstanding and Exercisable Weighted Average Remaining Weighted Average Exercise Price (in years) (per share) 2019 5,750,000 2.88 $ 13.00 2020 4,149,378 2.10 $ 6.50 2020 1 1,659,752 — $ — 2021 2,055,920 5.19 $ 1.69 2021 2 19,679,210 — $ — 33,294,260

SHARE-BASED COMPENSATION PLANS

SHARE-BASED COMPENSATION PLANS (Tables)	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Schedule of Share-based Compensation	Share-based compensation expense by classification for the three and nine months ended September 30, 2023 and 2022 are as follows: Three Months Ended Nine Months Ended (in thousands) September 30, 2023 September 30, 2022 September 30, 2023 September 30, 2022 Research and development $ (9) $ 334 $ 96 $ 921 General and administrative 125 351 638 974 Total $ 116 $ 685 $ 734 $ 1,895

ORGANIZATION, BASIS OF PRESEN_4

ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	3 Months Ended			9 Months Ended
	Sep. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) subsidiary	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)
Class of Stock [Line Items]
Number of wholly-owned subsidiaries formed | subsidiary				1
Accumulated deficit	$ (591,606,000)			$ (591,606,000)		$ (575,425,000)
Cash and cash equivalents	5,909,000			5,909,000		$ 21,837,000
Revenues	1,000,000	$ 8,000	$ 1,000,000	$ 1,008,000	$ 1,000,000
MD Anderson | Licensing Agreements | 2021 M.D. Anderson Option and License Agreement
Class of Stock [Line Items]
License maintenance fee earned during period	$ 1,000,000

ORGANIZATION, BASIS OF PRESEN_5

ORGANIZATION, BASIS OF PRESENTATION, AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued payroll	$ 89	$ 264
Accrued patient treatment costs	2	675
Accrued clinical research costs	494	841
Accrued manufacturing costs	105	434
Accrued professional services	373	207
Accrued other	142	56
Total accrued expenses and other current liabilities	$ 1,205	$ 2,477

ORGANIZATION, BASIS OF PRESEN_6

ORGANIZATION, BASIS OF PRESENTATION, AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Anti-dilutive Shares Excluded From Earnings Per Share Calculations (Details) - shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Total common stock equivalents (in shares)	10,883,193	14,154,122
Redeemable convertible series 1 preferred stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Total common stock equivalents (in shares)	4,520,000	4,520,000
Warrants to purchase common stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Total common stock equivalents (in shares)	5,750,000	5,750,000
Options to purchase common stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Total common stock equivalents (in shares)	215,206	3,658,489
Unvested shares of restricted stock units
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Total common stock equivalents (in shares)	397,987	225,633

FAIR VALUE OF MEASUREMENTS AND

FAIR VALUE OF MEASUREMENTS AND INVESTMENT SECURITIES - Assets Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Level 1
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total cash equivalents	$ 4,532	$ 20,024
Level 1 | Money market funds
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total cash equivalents	4,532	20,024
Level 2
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total cash equivalents	0	0
Level 2 | Money market funds
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total cash equivalents	0	0
Level 3
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total cash equivalents	0	0
Level 3 | Money market funds
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total cash equivalents	$ 0	$ 0

FAIR VALUE OF MEASUREMENTS AN_2

FAIR VALUE OF MEASUREMENTS AND INVESTMENT SECURITIES - Fair Value of Warrants (Details) - Warrant Derivative Liability	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Derivative [Line Items]
Risk-free interest rate	4.80%	4.10%
Volatility	143%	102%
Expected term (years)	2 years 10 months 17 days	3 years 7 months 17 days

FAIR VALUE OF MEASUREMENTS AN_3

FAIR VALUE OF MEASUREMENTS AND INVESTMENT SECURITIES - Derivative Liabilities Reported at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	$ 518	$ 809
Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	0	0
Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	0	0
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	$ 518	$ 809

PUBLIC OFFERING AND PRIVATE P_3

PUBLIC OFFERING AND PRIVATE PLACEMENT - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 04, 2021	Nov. 02, 2020	Aug. 21, 2019	Aug. 16, 2019	Sep. 30, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Common stock, par value (in dollars per share)					$ 0.01	$ 0.01
Common stock, issued (in shares)					9,784,677	8,682,447
Proceeds from issuance of redeemable convertible preferred stock in a public offering, net			$ 53.8
Proceeds upon entering into private placement agreement				$ 11.2
Series 1 Preferred
Class of Stock [Line Items]
Shares issuable per warrants (in shares)					10
Price per share (in dollars per share)					$ 100
December 2021 Private Placement
Class of Stock [Line Items]
Shares issuable per warrants (in shares)	20,559,210
Warrants to purchase aggregate shares of common stock (in shares)	2,055,920
Shares purchased by selling pre-funded warrant (in shares)	0.1
Price per share (in dollars per share)	$ 1.7024
Common stock, par value (in dollars per share)	0.0001
Warrant exercise price (in dollars per share)	$ 1.69
Expiration period	7 years
Proceeds from issuance of stock	$ 35
December 2021 Private Placement | Pre-Funded Warrant
Class of Stock [Line Items]
Shares purchased by selling pre-funded warrant (in shares)	1
November 2020 Underwritten Offering
Class of Stock [Line Items]
Shares issuable per warrants (in shares)		3,109,378
Warrants to purchase aggregate shares of common stock (in shares)		4,149,378
Shares purchased by selling pre-funded warrant (in shares)		1
Common stock, par value (in dollars per share)		$ 0.001
Warrant exercise price (in dollars per share)		$ 6.50
Expiration period		5 years
Proceeds from issuance of stock		$ 25
Common stock, issued (in shares)		1,040,000
November 2020 Underwritten Offering | Minimum
Class of Stock [Line Items]
Price of each share of common stock and accompanying common warrant (in dollars per share)		$ 6.024
November 2020 Underwritten Offering | Maximum
Class of Stock [Line Items]
Price of each share of common stock and accompanying common warrant (in dollars per share)		$ 6.025
Public Offering
Class of Stock [Line Items]
Price per share (in dollars per share)				$ 100
Shares issuable under warrants (in shares)				5,750,000
Public Offering | Series 1 Preferred
Class of Stock [Line Items]
Number of shares of common stock sold in offering (in shares)				575,000
Weighted average exercise price (in dollars per share)				$ 130
Public Offering | Common Stock
Class of Stock [Line Items]
Shares issuable per warrants (in shares)				10
Weighted average exercise price (in dollars per share)				$ 13
Class of warrant or right, notice period for percentage change				61 days
Public Offering | Common Stock | Minimum
Class of Stock [Line Items]
Warrants, limitations on ownership after exercise				9.99%
Public Offering | Common Stock | Maximum
Class of Stock [Line Items]
Warrants, limitations on ownership after exercise				19.99%
Private Placement | Series 2 Redeemable Convertible Non-voting Preferred Stock
Class of Stock [Line Items]
Price per share (in dollars per share)				$ 100
Number of shares of common stock sold in offering (in shares)				350,000
Shares issuable under warrants (in shares)				2,800,000
Weighted average exercise price (in dollars per share)				$ 10
Private Placement | Series 3 Redeemable Convertible Non-voting Preferred Stock
Class of Stock [Line Items]
Number of shares of common stock sold in offering (in shares)				250,000
Private Placement | Series 1 Preferred
Class of Stock [Line Items]
Price per share (in dollars per share)				$ 140
Shares issuable under warrants (in shares)				875,000
Weighted average exercise price (in dollars per share)				$ 14

PUBLIC OFFERING AND PRIVATE P_4

PUBLIC OFFERING AND PRIVATE PLACEMENT - Fair Value of Derivative Liability (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Warrant Derivative Liability
Change in fair value	$ (5)	$ 59	$ (291)	$ (827)
Warrant Derivative Liability |  Level 3
Warrant Derivative Liability
Balance, December 31, 2022			809
Change in fair value			(291)
Balance, September 30, 2023	$ 518		$ 518

PUBLIC OFFERING AND PRIVATE P_5

PUBLIC OFFERING AND PRIVATE PLACEMENT - Summary of Warrants Outstanding and Exercisable (Details)	Sep. 30, 2023 $ / shares shares
Warrants Outstanding and Exercisable [Abstract]
Warrant Outstanding (in shares)	33,294,260
Warrants Exercisable (in shares)	33,294,260
2019
Warrants Outstanding and Exercisable [Abstract]
Warrant Outstanding (in shares)	5,750,000
Warrants Exercisable (in shares)	5,750,000
Weighted Average Remaining Contractual Life	2 years 10 months 17 days
Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 13
2020
Warrants Outstanding and Exercisable [Abstract]
Warrant Outstanding (in shares)	4,149,378
Warrants Exercisable (in shares)	4,149,378
Weighted Average Remaining Contractual Life	2 years 1 month 6 days
Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 6.50
2020
Warrants Outstanding and Exercisable [Abstract]
Warrant Outstanding (in shares)	1,659,752
Warrants Exercisable (in shares)	1,659,752
Weighted Average Remaining Contractual Life	0 years
Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 0
2021
Warrants Outstanding and Exercisable [Abstract]
Warrant Outstanding (in shares)	2,055,920
Warrants Exercisable (in shares)	2,055,920
Weighted Average Remaining Contractual Life	5 years 2 months 8 days
Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 1.69
2021
Warrants Outstanding and Exercisable [Abstract]
Warrant Outstanding (in shares)	19,679,210
Warrants Exercisable (in shares)	19,679,210
Weighted Average Remaining Contractual Life	0 years
Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 0

REDEEMABLE CONVERTIBLE PREFER_2

REDEEMABLE CONVERTIBLE PREFERRED STOCK (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022	Aug. 31, 2019
Class of Stock [Line Items]
Preferred stock, authorized (in shares)				10,000,000
Preferred stock, par value (in dollars per share)				$ 0.01
Series 1 preferred stock	$ 31,618	$ 18,036
Redeemable convertible series 1 preferred stock
Class of Stock [Line Items]
Preferred stock, authorized (in shares)				1,517,500
Preferred stock, outstanding (in shares)	452,000
Preferred stock, issued (in shares)	452,000
Closing price of common stock (in dollars per share)	$ 25
Common stock redemption requirement, closing price, threshold period	180 days
Common stock redemption, average trading volume period	50 days
50-day trading volume on Nasdaq stock market (in shares)	50,000
Preferred stock, redemption amount	$ 45,200
Series 1 preferred stock	$ 31,600		$ 18,036
Shares issuable per warrants (in shares)	10
Price per share (in dollars per share)	$ 100
Series 2 Preferred Stock
Class of Stock [Line Items]
Preferred stock, authorized (in shares)				350,000
Preferred stock, outstanding (in shares)	0
Preferred stock, issued (in shares)	0
Series 3 Preferred Stock
Class of Stock [Line Items]
Preferred stock, authorized (in shares)				250,000
Preferred stock, outstanding (in shares)	0
Preferred stock, issued (in shares)	0

SHARE-BASED COMPENSATION PLAN_2

SHARE-BASED COMPENSATION PLANS - Narrative (Details) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($) plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation plans | plan	5
Compensation cost not yet recognized | $	$ 0.1
Period for recognition	2 months 12 days
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period	10 years
Options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years
Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years

SHARE-BASED COMPENSATION PLAN_3

SHARE-BASED COMPENSATION PLANS - Expense by Classification (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 116	$ 685	$ 734	$ 1,895
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	(9)	334	96	921
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total	$ 125	$ 351	$ 638	$ 974

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Details) $ in Thousands	Dec. 10, 2015 USD ($)	Jun. 10, 2015 USD ($) product	Dec. 20, 2022 licenseAgreement
Loss Contingencies [Line Items]
Number of license agreements terminated | licenseAgreement			2
Agensys, Inc. | Licensing Agreements
Loss Contingencies [Line Items]
Nonrefundable upfront fee	$ 3,000
Milestone payments upon first achievement of specified clinical milestones	5,000
Milestone payments upon achievement of specified clinical milestones for each licensed product	50,000
Milestone payments upon achievement of sales milestones	75,000
Option exercise fee	5,000
Milestone payments reduced upon exercise of option	$ 65,000
Termination period, number of years after first commercial sale of licensed product	10 years
Termination period, notice of failure on uncured items	60 days
Period of notice of failure on uncured items, if material breach is related to failure to make payments	30 days
BioVec Pharma Inc | Licensing Agreements
Loss Contingencies [Line Items]
Nonrefundable upfront fee		$ 100
Milestone payments upon first achievement of specified clinical milestones		$ 250
Termination period, notice of failure on uncured items		60 days
Upfront fee payment period, number of days from effective date		10 days
License costs due upon first release of product		$ 300
License costs due upon first release of product, period of payment		10 days
License maintenance fee earned during period		$ 150
License agreement, annual fee period, from first IND filing		30 days
Milestone payments, number of initial products | product		3
License agreement, milestone payments upon receipt of FDA or EMA registration		$ 2,000
Termination notice period for any other breach		90 days
Termination period, after insolvency event		30 days