0001628280-21-010329 | 10-Q | XBRL Viewer | Bellicum Pharmaceuticals INC

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Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2021	May 10, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
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	832
Local Phone Number	384-1100
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	BLCM
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 (in shares)		8,397,803
Entity Central Index Key	0001358403
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 28,082	$ 35,495
Restricted cash	1,501	1,501
Accounts receivable, interest and other receivables	375	2
Prepaid expenses and other current assets	1,481	802
Assets held for sale	0	1,643
Total current assets	31,439	39,443
Operating lease right-of-use assets	0	645
Property and equipment, net	63	189
Other assets	5	307
Total assets	31,507	40,584
Current liabilities:
Accounts payable	669	891
Accrued expenses and other current liabilities	5,120	4,165
Warrant derivative liability	11,863	10,345
Private placement option liability	8,622	7,803
Current portion of lease liabilities	31	825
Liabilities held for sale	0	672
Total current liabilities	26,305	24,701
Long-term lease liabilities	27	344
Total liabilities	26,332	25,045
Commitments and contingencies
Redeemable preferred stock: $0.01 par value; 10,000,000 shares authorized	18,036	18,036
Stockholders’ deficit:
Common stock, $0.01 par value; 80,000,000 shares authorized at March 31, 2021 and December 31, 2020, 8,386,019 shares issued and 8,318,273 shares outstanding at March 31, 2021; 8,385,650 shares issued and 8,317,904 shares outstanding at December 31, 2020	84	84
Treasury stock: 67,746 shares held at March 31, 2021 and December 31, 2020	(5,056)	(5,056)
Additional paid-in capital	544,464	543,561
Accumulated other comprehensive loss	(339)	(339)
Accumulated deficit	(552,014)	(540,747)
Total stockholders’ deficit	(12,861)	(2,497)
Total liabilities, preferred stock and stockholders' deficit	$ 31,507	$ 40,584

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
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)	80,000,000	80,000,000
Common stock, issued (in shares)	8,386,019	8,385,650
Common stock, outstanding (in shares)	8,318,273	8,317,904
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 Statements of Operations and Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Operating expenses
Research and development	$ 6,460	$ 10,448
General and administrative	2,012	4,171
Total operating expenses	8,472	14,619
Loss on lease termination	464	0
Loss from operations	(8,936)	(14,619)
Other income (expense):
Interest income	10	354
Interest expense	(4)	(985)
Change in fair value of warrant and private placement option liabilities	(2,337)	32,826
Total other (expense) income	(2,331)	32,195
Net (loss) income	(11,267)	17,576
Less: undistributed earnings to participating securities	0	(12,084)
Net (loss) income attributable to common shareholders	$ (11,267)	$ 5,492
Net income (loss) per common share attributable to common shareholders, basic (in USD per share)	$ (1.12)	$ 1.09
Net income (loss) per common share attributable to common shareholders, diluted (in USD per share)	$ (1.12)	$ 1.09
Weighted average shares for basic net Loss) income per share (in shares)	10,034,970	5,039,695
Weighted-average shares outstanding, diluted (in shares)	10,034,970	5,040,056
Other comprehensive (loss) income:
Foreign currency translation adjustment	$ 0	$ (13)
Comprehensive (loss) income	$ (11,267)	$ 17,563

Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders’ Deficit $ in Thousands	USD ($)	Common Stock USD ($) shares	Treasury Stock USD ($) shares	Additional Paid-In Capital USD ($)	Accumulated Deficit USD ($)	Accumulated Other Comprehensive Loss USD ($)	Series 1 redeemable convertible non-voting preferred stock USD ($) shares
Preferred stock, beginning balance (in shares) at Dec. 31, 2019 \| shares							538,000
Preferred stock, beginning balance at Dec. 31, 2019							$ 21,468
Preferred stock, ending balance (in shares) at Mar. 31, 2020 \| shares							534,000
Preferred stock, ending balance at Mar. 31, 2020							$ 21,308
Balance, beginning of period (in shares) at Dec. 31, 2019 \| shares		5,076,593	67,746
Balance, beginning of period at Dec. 31, 2019	$ (26,217)	$ 507	$ (5,056)	$ 511,684	$ (533,025)	$ (327)
Increase (Decrease) in Stockholders' Equity
1-for-10 reverse stock split		$ (457)		457
Reverse stock split ratio		0.01
Share-based compensation	1,323			1,323
Issuance of common stock upon vesting of restricted stock units (in shares) \| shares		1,045
Issuance of common stock upon vesting of restricted stock units	0	$ 0		0
Conversion of redeemable preferred stock into common stock (in shares) \| shares		40,000					(4,000)
Conversion of redeemable convertible preferred stock into common stock	160	$ 1		159			$ (160)
Comprehensive income	17,563				17,576	(13)
Balance, end of period (in shares) at Mar. 31, 2020 \| shares		5,117,638	67,746
Balance, end of period at Mar. 31, 2020	(7,171)	$ 51	$ (5,056)	513,623	(515,449)	(340)
Preferred stock, beginning balance (in shares) at Dec. 31, 2020 \| shares							452,000
Preferred stock, beginning balance at Dec. 31, 2020	18,036						$ 18,036
Preferred stock, ending balance (in shares) at Mar. 31, 2021 \| shares							452,000
Preferred stock, ending balance at Mar. 31, 2021	18,036						$ 18,036
Balance, beginning of period (in shares) at Dec. 31, 2020 \| shares		8,385,650	67,746
Balance, beginning of period at Dec. 31, 2020	(2,497)	$ 84	$ (5,056)	543,561	(540,747)	(339)
Increase (Decrease) in Stockholders' Equity
Share-based compensation	903			903
Exercise of restricted stock unit awards (in shares) \| shares		369
Exercise of restricted stock unit awards	0	$ 0		0
Comprehensive income	(11,267)				(11,267)	0
Balance, end of period (in shares) at Mar. 31, 2021 \| shares		8,386,019	67,746
Balance, end of period at Mar. 31, 2021	$ (12,861)	$ 84	$ (5,056)	$ 544,464	$ (552,014)	$ (339)

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities:
Net (loss) income	$ (11,267)	$ 17,576
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation	903	1,323
Depreciation and amortization expense	47	537
Change in fair value of warrant and private placement option liabilities	2,337	(32,826)
Amortization of right-of-use assets	33	85
Accretion of lease liability	31	(442)
Amortization of deferred issuance costs	0	214
Loss on lease termination	464	0
Changes in operating assets and liabilities:
Accounts receivable, interest and other receivables	0	257
Prepaid expenses and other assets	(679)	(435)
Accounts payable	(222)	(849)
Accrued liabilities and other	60	(1,695)
Net cash used in operating activities	(8,293)	(16,255)
Cash flows from investing activities:
Proceeds from sale of property and equipment	900	0
Purchases of property and equipment	0	(37)
Net cash provided by (used in) investing activities	900	(37)
Cash flows from financing activities:
Payment on debt	0	(2,000)
Payment on financing lease obligations	(20)	(17)
Net cash used in financing activities	(20)	(2,017)
Effect of exchange rate changes on cash	0	(13)
Net change in cash, cash equivalents, and restricted cash	(7,413)	(18,322)
Cash, cash equivalents and restricted cash at beginning of period	36,996	93,816
Cash, cash equivalents and restricted cash at end of period	29,583	75,494
Supplemental cash flow information:
Cash paid during the period for interest	0	792
Non-cash investing and financing activities:
Conversion of redeemable preferred stock into common stock	0	160
Reclassification of property and equipment, net to assets held for sale	$ 0	$ 199

ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

3 Months Ended

Mar. 31, 2021

Organization, Consolidation and Presentation of Financial Statements [Abstract]

ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Organization

Bellicum Pharmaceuticals, Inc. (“Bellicum”) is a clinical stage biopharmaceutical company focused on discovering and developing novel cellular immunotherapies for various forms of cancer. Bellicum is devoting substantially all of its present efforts to developing next-generation CAR-T product candidates in cellular immunotherapy.

Bellicum has two wholly-owned subsidiaries, Bellicum Pharma Limited, a private limited company organized under the laws of the United Kingdom, and Bellicum Pharma GmbH, a private limited liability company organized under German law. Both were formed for the purpose of developing product candidates in Europe. Bellicum, Bellicum Pharma Limited 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.

Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision-maker. The Company has determined that it has one operating and reporting segment as it allocates resources and assesses financial performance on a consolidated basis. The Company’s chief operating decision maker is its Chief Executive Officer who manages operations and reviews the financial information as a single operating segment for purposes of allocating resources and evaluating its financial performance.

Reverse Stock Split

On February 5, 2020, the Company filed a Certificate of Amendment of the Amended and Restated Certificate of Incorporation with the Secretary of State of the State of Delaware to (i) effect a reverse stock split of all issued and outstanding shares of the Company’s common stock at a ratio of 1-for-10 and (ii) reduce the number of authorized shares of the Company’s common stock from 200,000,000 to 40,000,000. The accompanying consolidated financial statements and notes to the consolidated financial statements gives retroactive effect to the reverse stock split for all periods presented.

On June 15, 2020, the Company filed with the Secretary of State of the State of Delaware a Second Certificate of Amendment to the Company’s Amended and Restated Certificate of Incorporation to increase the authorized number of shares of the Company’s common stock from 40,000,000 shares to 80,000,000 shares

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 unaudited condensed consolidated balance sheet as of December 31, 2020 has been derived from the audited consolidated financial statements at that date but does not include all information and footnotes required by GAAP for complete financial statements. 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, 2020, as filed with the SEC on March 31, 2021.

The accompanying interim condensed financial statements have been prepared on a going concern basis, which assumes that the Company will continue to realize its assets and discharge its liabilities in the normal course of business. However, as of March 31, 2021 and December 31, 2020, the Company had an accumulated deficit of $552.0 million and $540.7 million, respectively, and at March 31, 2021, the Company had cash, cash equivalents and restricted cash of approximately $29.6 million. Based on the Company’s current business plan, management believes that existing cash and cash equivalents, revenues and other cash inflows will be insufficient to fund its operations within one year from the date these financial statements are issued, and therefore, substantial doubt about the entity’s ability to continue as a going concern exists. 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. The Company has recorded losses from operations since its inception and if the Company does not successfully obtain regulatory approval and commercialize any of its product candidates, the Company will not be able to achieve profitability.

The Company is subject to risks common to companies in the biotechnology industry and the future success of the Company is dependent on its ability to successfully complete the development of, and obtain regulatory approval for, its product candidates, manage the growth of the organization, obtain additional financing necessary in order to develop, launch and commercialize its product candidates, and compete successfully with other companies in its industry.

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 interim financial statements are issued based on the expected cash burn rate. The Company may be required to raise additional capital to fund future operations through the sale of additional equity, incurrence of debt, the entry into licensing or collaboration agreements with partners, grants or other sources of financing. Sufficient funds may not be available to the Company at all or on attractive terms when needed from equity or debt financings. If the Company is unable to obtain additional funding from these or other sources when needed, or to the extent needed, it may be necessary to significantly reduce its controllable and variable expenditures and current rate of spending through reductions in staff and delaying, scaling back, or suspending certain research and development, sales and marketing programs and other operational goals. Moreover, if we do not obtain such additional funds, there could be substantial doubt about our ability to continue as a going concern and increased risk of insolvency, which could result in a total loss of investment to our stockholders and other security holders.

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.

Significant Accounting Policies

There have been no significant changes to the accounting policies during the three months ended March 31, 2021, 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 for the fiscal year ended December 31, 2020.

Cash, Cash Equivalents and Restricted Cash

The Company considers all short-term, highly liquid investments with maturity of three months or less from the date of purchase and that can be liquidated without prior notice or penalty, to be cash equivalents.

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the balance sheets that sum to the total of the same such amounts shown in the statements of cash flows.


(in thousands)	March 31, 2021		December 31, 2020
Cash and cash equivalents	$	28,082	$	35,495
Restricted cash	1,501		1,501
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$	29,583	$	36,996

In connection with the closing of the Asset Purchase Agreement with M.D. Anderson on April 14, 2020, $1.5 million of the cash proceeds received are subject to certain escrow provisions and recorded as restricted cash. The funds are required to be held for a period of up to 18 months subsequent to the April 14, 2020 closing date and are listed as Restricted cash at March 31, 2021, and December 31, 2020.

Disposition of Assets and Liabilities Held for Sale and Held for Use

In the fourth quarter of 2020, in connection with the Company's restructuring plan, Management elected to seek an exit to its leased R&D facility in Houston, Texas. As a result of this decision, the Company reclassified the assets and liabilities associated with the leased facility as held for sale. The reclassified assets and liabilities included a right-of-use asset of $0.5 million, property and equipment of $2.3 million and the related lease liability of $0.7 million. Based on the cost to exit the lease and the net realizable value of the related assets the Company recognized an impairment charge of $1.3 million in the fourth quarter of 2020.

The disposal of the assets and liabilities associated with the facility was completed on February 26, 2021. Under the terms of the agreement a third party assumed the lease for the facility. In addition, the third party paid $1.1 million to the Company for substantially all of the property, and equipment associated with the location. The consideration included $0.9 million in cash and an unsecured promissory note for $0.2 million.

On March 15, 2021 the Company entered an agreement to terminate its sub-lease of the South San Francisco office space contingent upon consent of the prime lessor. Under the terms of the agreement, the company agreed to pay a lease termination fee of $0.9 million while the security deposit of $0.2 million will be returned to the Company. The decision to exit this lease reflects the ability of the Company to carry on administrative function remotely. On March 26, 2021, the Company met all of the conditions of the agreement and disposed of substantially all of the assets and liabilities associated with the lease including the a right-of-use asset of $0.6 million, leased equipment with net book value less than $0.1 million, and the related lease liability of $1 million. The Company recognized a loss on termination of $0.5 million during the three months ended March 31, 2021.

Accrued Expenses and Other Current Liabilities

Accrued expenses and other liabilities consist of the following:


(in thousands)	March 31, 2021		December 31, 2020
Accrued payroll	$	255	$	1,029
Accrued patient treatment costs	1,345		899

Accrued manufacturing costs	24		24
Accrued professional services	404		294
Accrued lease termination fee	895		—
Accrued other	2,197		1,919
Total accrued expenses and other current liabilities	$	5,120	$	4,165

Warrant Derivatives

Freestanding warrants are classified as liabilities in the accompanying condensed consolidated balance sheets as they are exercisable for multiple underlying instruments that are potentially redeemable. The Company accounts for these warrants at fair value on the date of issuance and are subject to re-measurement to fair value at each balance sheet date. Any change in fair value is recognized as a component of other income (expense) on the accompanying condensed consolidated statements of operations and comprehensive (loss) income. The Company will continue to adjust the liability for changes in fair value until the earlier of the exercise or expiration of the warrants or a change in control, as defined. The warrants are freely exercisable at any time from the issuance date until the expiration date, provided exercise does not cause a warrant holder to exceed a pre-determined beneficial ownership limit.

The Company estimates the fair value of these liabilities using the Black-Scholes valuation technique which utilizes assumptions including (i) the fair value of the underlying stock at the valuation measurement date, (ii) volatility of the price of the underlying stock, (iii) the expected term, and (iv) risk-free interest rates.

Private Placement Option

The Company has entered into a security purchase agreement that contains a call option on preferred shares that are puttable outside the control of the Company. The Company recorded the option as a liability and measured the fair value of the option at the time of issuance. The Company will re-measure the option to fair value at each balance sheet date and record changes in fair value in other income (expense) in the accompanying condensed consolidated statement of operations and comprehensive income (loss) at each reporting period. Offering expenses arising from the issuance of the private placement option were expensed as incurred.

The Company estimates the fair value of these liabilities using a binomial lattice model, which utilizes assumptions including (i) the fair value of the underlying stock at the valuation measurement date, (ii) volatility of the price of the underlying stock, (iii) the expected term, and (iv) risk-free interest rates.

Preferred Stock

Preferred shares issued by the Company that are subject to mandatory redemption are classified as liability instruments in the accompanying condensed consolidated balance sheets and are measured at fair value at the date of issuance. Conditionally redeemable preferred shares (including preferred shares that feature redemption rights that are either within the control of the holder or subject to redemption upon the occurrence of uncertain events not solely within the Company’s control) are classified within mezzanine equity in the accompanying condensed consolidated balance sheets. At all other times, preferred shares are classified within stockholders’ deficit.

Operating Leases

At the inception of a contractual arrangement, the Company determines whether the contract contains a lease by assessing whether there is an identified asset and whether the contract conveys the right to control the use of the identified asset in exchange for consideration over a period of time. If both criteria are met, upon lease commencement, the Company records a lease liability which represents the Company’s obligation to make lease payments arising from the lease, and a corresponding right-of-use (“ROU”) asset which represents the Company’s right to use an underlying asset during the lease term.

Operating leases are recognized as ROU assets and operating lease liabilities on the balance sheet based on the present value of the future minimum lease payments over the lease term at commencement date calculated using the Company's incremental borrowing rate applicable to the underlying asset unless the implicit rate is readily determinable. Any lease incentives received are deferred and recorded as a reduction of the ROU asset and amortized over the term of the lease. Rent expense, comprised of amortization of the ROU asset and the implicit interest accreted on the operating lease liability, is recognized on a straight-line basis over the lease term. The Company determines the lease term as the noncancellable period of the lease and may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise such options. Leases with a term of 12 months or less are not recognized on the balance sheets.

Fair Value of Financial Instruments

Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in an orderly transaction between market participants in a principal market on the measurement date.

Accounting standards include disclosure requirements around fair values used for certain financial instruments and establish a fair value hierarchy. The three-tier hierarchy defines a three-tiered valuation hierarchy for disclosures that prioritizes valuation inputs into three levels based on the extent to which inputs used in measuring fair value are observable in the market, as described further in Note 2.

Observable inputs reflect readily obtainable data from independent sources, and unobservable inputs reflect the Company’s market assumptions.

These inputs are classified into the following hierarchy:

Level 1 Inputs - quoted prices (unadjusted) in active markets for identical assets 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.

Financial Instruments and Credit Risks

Financial instruments that potentially subject the Company to credit risk include cash and cash equivalents and accounts receivable. Cash is deposited in demand accounts in federally insured domestic institutions to minimize risk. Insurance is provided through the Federal Deposit Insurance Corporation and Security Investor Protection Corporation. Although the balances in these accounts exceed the federally insured limit from time to time, the Company has not incurred losses related to these deposits.

Equity Issuance Costs

Equity issuance costs represent costs paid to third parties in order to obtain equity financing. The costs related to preferred and common stock have been netted against the proceeds of the equity issuances.

Net Income (Loss) per Share of Common Stock Attributable to Common Stockholders

Basic and diluted net (loss) income per share attributable to common stockholders is based on the more dilutive method of either the two-class method or the treasury stock method. Basic net (loss) income per share attributable to common stockholders is calculated by dividing the net (loss) income attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period without consideration for common stock equivalents. Undistributed earnings allocated to participating securities are subtracted from net income in determining net income attributable to common stockholders. Diluted net (loss) income per share gives effect to dilutive stock options, warrants and other potentially dilutive common stock equivalents outstanding during the period, assuming the exercise of all “in-the-money” common stock equivalents based on the average market price during the period.

For warrants that are recorded as a liability in the accompanying condensed consolidated balance sheets, the calculation of diluted loss per share requires that, to the extent the average market price of the underlying shares for the reporting period exceeds the exercise price of the warrants and the presumed exercise of the warrants is dilutive to loss per share for the period, an adjustment is made to net loss used in the calculation to remove the change in fair value of the warrants from the numerator for the period. Likewise, an adjustment to the denominator is required to reflect the related dilutive shares, if any, under the treasury stock method.

The following table sets forth the computation of basic and diluted earnings per share:


(in thousands, except share and per share amounts)	March 31, 2021		March 31, 2020
Net (loss) income per share - basic:
Net (loss) income	$	(11,267)	$	17,576
Less: undistributed earnings to participating securities	—		(12,084)
Net (loss) income attributed to common shareholders	$	(11,267)	$	5,492

Weighted average shares for basic net (loss) income per share	10,034,970		5,039,695
Basic net (loss) income per share	$	(1.12)	$	1.09

Net (loss) income per share - diluted:
Net (loss) income attributed to common shareholders	$	(11,267)	$	5,492

Weighted average shares for basic net (loss) income per share	10,034,970		5,039,695
Effect of dilutive securities:
Stock options and restricted stock units	—		361
Weighted average shares for diluted net (loss) income per share	10,034,970		5,040,056
Diluted net (loss) income per share	$	(1.12)	$	1.09

The following outstanding shares of common stock equivalents were excluded from the computations of diluted net income (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.


	March 31, 2021	March 31, 2020
Common Stock Equivalents:	Number of Shares
Redeemable convertible series 1 preferred stock	452,000	—
Warrants to purchase common stock	11,616,080	—
Private placement option	9,675,000	9,675,000
Options to purchase common stock	1,400,470	1,051,665
Unvested shares of restricted stock units	262,010	4,334
Total common stock equivalents	23,405,560	10,730,999

New Accounting Requirements and Disclosures

Fair Value Measurement

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which modifies fair value disclosures and removes some disclosure requirements for both public and private companies. In addition, public companies are subject to some new disclosure requirements which requires to disclose the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period and the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. ASU No. 2018-13 is effective for all entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted. The Company adopted the standard effective January 1, 2020 with no material effect on its financial statements.

Financial Instruments – Credit Losses

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires the measurement of all expected credit losses for financial assets including trade receivables held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. ASU No. 2016-13 is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. The Company adopted the standard effective January 1, 2020 with no material effect on its financial statements. Subsequent to the issuance of ASU 2016-13, the FASB issued ASU 2018-19, Codification Improvements to Topic 326, Financial Instruments - Credit Losses. This ASU does not change the core principle of the guidance in ASU 2016-13, instead these amendments are intended to clarify and improve operability of certain topics included within the credit losses guidance. The FASB also subsequently issued ASU No. 2019-04, Codification Improvements to Topic 326, Financial Instruments—Credit Losses, Derivatives and Hedging (Topic 815), and Financial Instruments (Topic 842), which did not change the core principle of the guidance in ASU 2016-13 but clarified that expected recoveries of amounts previously written off and expected to be written off should be included in the valuation account and should not exceed amounts previously written off and expected to be written off. The guidance is effective for fiscal years, and interim periods within those years, beginning after December 15, 2019 for public business entities, excluding smaller reporting companies. Early adoption is permitted. As a smaller reporting company, the guidance will be effective for the Company during the first quarter of 2023. The Company is in the process of assessing the impact adoption will have on its consolidated financial statements.

Income Taxes

In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes (Topic 740). The guidance eliminates certain exceptions for recognizing deferred taxes for investments, performing intraperiod allocation and calculating income taxes in interim periods. This guidance also includes guidance to reduce complexity in certain areas, including recognizing deferred taxes for tax goodwill and allocating taxes to members of a consolidated group. ASU 2019-12 is effective for annual and interim periods in fiscal years beginning after December 15, 2019. The Company adopted the standard effective January 1, 2020 with no material effect on its financial statements.

Investments

In January 2020, the FASB issued Accounting Standards Update No. 2020-01, Investments—Equity Securities (Topic 321), Investments—Equity Method and Joint Ventures (Topic 323), and Derivatives and Hedging (Topic 815)—Clarifying the Interactions between Topic 321, Topic 323, and Topic 815 (a consensus of the Emerging Issues Task Force), which clarifies the interaction of the accounting for equity securities, investments accounted for under the equity method, and certain forward contracts and purchased options. This update is effective for fiscal years beginning after December 15, 2020, and interim periods within those fiscal years, and early adoption is permitted. The Company is in the process of determining the impact the adoption will have on its consolidated financial statements as well as whether to early adopt the new guidance.

FAIR VALUE MEASUREMENTS AND INVESTMENT SECURITIES

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS AND INVESTMENT SECURITIES

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 March 31, 2021 and December 31, 2020:


	Fair Value at March 31, 2021						Fair Value at December 31, 2020
(in thousands)	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
Cash equivalents:
Money market funds and treasury bills	$	20,473	$	—	$	—	$	27,463	$	—	$	—
Total cash equivalents	$	20,473	$	—	$	—	$	27,463	$	—	$	—

As of March 31, 2021 and December 31, 2020, $1.5 million of restricted cash on the Company's balance sheet is held in a money market fund.

Money market funds, U.S. Treasury, U.S. government agency-backed securities, corporate debt securities and municipal bonds are valued based on various observable inputs such as benchmark yields, reported trades, broker/dealer quotes, benchmark securities and bids.

Warrant Derivative Liability and Private Placement Option Liability

The Company's financial liabilities recorded at fair value on a recurring basis include the fair values of the warrant derivative liability and the private placement option liability. As of March 31, 2021, the fair values of the warrant derivative liability and the private placement option liability are classified as current liabilities in the accompanying condensed consolidated balance sheets. These liabilities will be shown as current liabilities on the balance sheet when it is deemed more probable than not by management to be exercised within one year.

Inputs used to determine estimated fair value (Level 3) of the warrants include the fair value of the underlying stock relative to the warrant exercise price at the valuation measurement date, volatility of the price of the underlying stock, the expected term of the warrants, and risk-free interest rates.

The fair value of the warrants has been estimated with the following weighted-average assumptions, including the most sensitive input, volatility:


	March 31, 2021	December 31, 2020
Risk-free interest rate	0.99%	0.46%
Volatility	95.00%	90.00%
Expected term (years)	5.39	5.64

Inputs used to determine estimated fair value (Level 3) of the private placement option include the fair value of the underlying stock relative to the preferred share conversion price and warrant exercise price at the valuation measurement date, volatility of the price of the underlying stock, the expected term of the call option on the preferred shares and expected term of the warrants, and risk-free interest rates.

The fair value of the private placement option has been estimated with the following weighted-average assumptions, including the most sensitive input, volatility:


	March 31, 2021		December 31, 2020
Risk-free interest rate	1.50	%	0.77	%
Volatility	95.00	%	90.00	%
Expected term (years)	7.00		7.00

The following table provides the warrant derivative and private placement option reported at fair value and measured on a recurring basis:


	Fair Value at March 31, 2021						Fair Value at December 31, 2020
(in thousands)	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
Warrant derivative liability	$	—	$	—	$	11,863	$	—	$	—	$	10,345
Private placement option liability	—		—		8,622		—		—		7,803
Total fair value	$	—	$	—	$	20,485	$	—	$	—	$	18,148

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.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

LEASES

3 Months Ended

Mar. 31, 2021

Leases [Abstract]

LEASES

The Company determines whether an arrangement is a lease at its inception. Operating leases relate primarily to office space and manufacturing facilities with remaining lease terms of one year to seven years, some of which include options to extend the lease term for up to five years. Management considered the options in determining the lease term used to establish the Company's ROU assets and lease liabilities.

As most of the Company's leases do not provide an implicit rate, the Company's incremental borrowing rate based on the information available at lease commencement date was used to determine the present value of lease payments.

Components of lease cost are as follows:


	Three Months Ended
(in thousands)	March 31, 2021		March 31, 2020
Finance lease cost:
Amortization of leased asset	$	10	$	18
Interest on lease liabilities	4		6
Operating lease cost	54		305
Short-term lease cost	52		34
Total lease cost	$	120	$	363

PUBLIC OFFERING AND PRIVATE PLACEMENT

3 Months Ended

Mar. 31, 2021

Statement of Stockholders' Equity [Abstract]

PUBLIC OFFERING AND PRIVATE PLACEMENT

November 2020 Underwritten Offering

In November 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 was 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 will be immediately exercisable upon issuance, provided that the holder will be 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. No shares have been exercised as of the balance sheet date.

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 has 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 purchase and sale of the securities issuable under the private placement agreement may occur in two or more separate closings, each to be conducted at the Purchasers’ discretion within five days’ notice to the Company. The purchase and sale were subject to the Company’s obtaining stockholder approval for additional authorized shares of Common Stock or a reverse stock split (the “Required Stockholder Approval”), which occurred in the first quarter of 2020. The right of the Purchasers to purchase such securities will expire two and a half years after the Required Stockholder Approval, on June 15, 2022, with respect to the Series 2 Preferred Stock, and three years after such stockholder approval, on January 15, 2023, with respect to the Series 3 Preferred Stock, if not exercised prior to that date. No shares have been exercised as of the balance sheet date.

The Company received $11.2 million in option proceeds, net of offering costs, upon the execution of the Securities Purchase Agreement. Total offering costs incurred by the Company related to the Public Warrants, Private Warrants and options amounted to $3.0 million.

The following table reflects the fair value roll forward reconciliation of the warrant derivative and private placement option liabilities for the period ended March 31, 2021:


(in thousands)	Warrant Derivative Liability		Private Placement Option Liability		Total
Balance, December 31, 2020	$	10,345	$	7,803	$	18,148
Change in fair value	1,518		819		2,337
Balance, March 31, 2021	$	11,863	$	8,622	$	20,485

REDEEMABLE CONVERTIBLE PREFERRED STOCK	3 Months Ended
REDEEMABLE CONVERTIBLE PREFERRED STOCK	Mar. 31, 2021
Equity [Abstract]
REDEEMABLE CONVERTIBLE PREFERRED STOCK	REDEEMABLE CONVERTIBLE PREFERRED STOCK In August 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, of which the Company has designated 1,517,500 shares as Series 1 redeemable convertible non-voting preferred stock, 350,000 shares as Series 2 redeemable convertible non-voting preferred stock and 250,000 shares as Series 3 redeemable convertible non-voting preferred stock. There were 452,000 shares of Series 1 preferred stock issued and outstanding as of March 31, 2021. There were no shares of Series 2 or 3 preferred stock issued and outstanding as of March 31, 2021. As of March 31, 2021, the Company classified the Series 1 Preferred Stock as mezzanine equity, as 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. The Series 1 Preferred Stock is not currently redeemable and is only redeemable upon a fundamental change in a redemption price. The Company does not believe a fundamental change is considered probable until it occurs. Subsequent adjustment of the amount presented in mezzanine equity to its redemption amount is unnecessary if it is not probable that the instrument will become redeemable. As (i) the Series 1 Preferred Stock is only redeemable upon a fundamental change, the occurrence of which is not probable, and (ii) the occurrence of Transition Date (defined below) is probable, the Company did not accrete the Series 1 Preferred Stock to its redemption amount. 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 the date that is the fifth (5th) anniversary of the initial issue date of the applicable series of preferred stock, all or any portion of the preferred stock is redeemable at the option of the holder at a redemption price of $100.00 per share (for Series 1 and Series 2 Preferred Stock) and $140.00 per share (for Series 3 Preferred Stock). 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 below) is met (the “Series 1 Transition Date”); •With respect to the Series 2 preferred stock, the first date following the six-month anniversary of the Series 1 Transition Date on which each of the Conditions is met (the “Series 2 Transition Date”); and •With respect to the Series 3 preferred stock, the first date following the six-month anniversary of the Series 2 Transition Date on which each of the Conditions is met. 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 and Series 2 preferred stock) and $35.00 per share (for the Series 3 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. 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

3 Months Ended

Mar. 31, 2021

Share-based Payment Arrangement [Abstract]

SHARE-BASED COMPENSATION PLANS

Share-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 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 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 four years, and have a term of up to 10 years. Unexercised stock options terminate on the expiration date of the grant. The Company recognizes the share-based compensation expense over the requisite service period of the individual grantees, which generally equals the vesting period.

2019 Equity Incentive Plan

The 2019 Plan is designed to secure and retain the services of the Company’s employees and directors. The 2019 Plan is successor to and continuation of the 2014 Equity Incentive Plan, as amended, the (“2014 Plan”), and no additional awards may

be issued from the 2014 Plan. Subject to adjustment for certain changes in the Company’s capitalization, the aggregate number of shares of common stock that may be issued under the 2019 Plan (the “Share Reserve”) will not exceed the sum of (i) 250,000 new shares, plus (ii) an additional 600,000 shares that were approved at the Company’s Special Meeting of Stockholders in January 2020, (iii) an additional 500,000 shares that were approved at the Company's Annual Meeting of Stockholders in June 2020, and plus (iii) the Prior Plans’ Returning Shares, as defined in the 2019 Plan documents, in an amount not to exceed 600,540 shares, including any stock award granted under the 2014 Plan, 2011 Stock Option Plan, as amended, or 2006 Stock Option Plan, as amended, that were outstanding as of the date the 2019 Plan was approved by the Company's stockholders, as such shares become available from time to time.

The following shares of common stock (the “2019 Plan Returning Shares”) will also become available again for issuance under the 2019 Plan: (i) any shares subject to a stock award granted under the 2019 Plan that are not issued because such stock award expires or otherwise terminates without all of the shares covered by such stock award having been issued; (ii) any shares subject to a stock award granted under the 2019 Plan that are not issued because such stock award is settled in cash; and (iii) any shares issued pursuant to a stock award granted under the 2019 Plan that are forfeited back to or repurchased by the Company because of a failure to vest.

The 2019 Plan provides for the grant of incentive stock options, non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance stock awards, and other stock awards.

The following table summarizes the stock option activity for all stock plans during the three months ended March 31, 2021:


			Options and Inducement Awards
Outstanding at December 31, 2020			1,510,968
Granted			104,000
Exercised			—
Forfeited			(214,498)
Outstanding at March 31, 2021			1,400,470
Exercisable at March 31, 2021			350,101

The following table summarizes the restricted stock unit award activity for all stock plans during the three months ended March 31, 2021:


			Restricted Stock Unit Awards
Outstanding at Outstanding at December 31, 2020			129,861
Granted			135,251
Vested			(596)
Forfeited			(2,506)
Outstanding at March 31, 2021			262,010

2014 Employee Stock Purchase Plan

The 2014 Employee Stock Purchase Plan (the “ESPP”) provides for eligible Company employees, as defined by the ESPP, to be given an opportunity to purchase the Company's common stock at a discount, through payroll deductions, with stock purchases being made upon defined purchase dates. The ESPP authorizes the issuance of up to 55,000 shares of the Company’s common stock to participating employees and allows eligible employees to purchase shares of common stock at a 15% discount from the lesser of the grant date or purchase date fair market value. There were no shares purchased by employees under the ESPP in either of the three months ended March 31, 2021 and 2020.

A summary of activity within the ESPP follows:


	Three Months Ended
(in thousands)	March 31, 2021		March 31, 2020
Deductions from employees	$	—	$	64
Share-based compensation expense recognized	—		25
Remaining share-based compensation expense	—		157

The ESPP has been suspended since December, 2020, resulting in the inactivity during the first quarter. As of March 31, 2021, there were 18,488 shares available for issuance under the ESPP.

Share-Based Compensation Expense

The fair value of option grants is determined using the Black-Scholes option-pricing model and has been estimated with the following weighted-average assumptions:


	Three Months Ended
	March 31, 2021		March 31, 2020
Risk-free interest rate	0.90	%	1.40	%
Volatility	90.67	%	80.69	%
Expected life (years)	5.64		6.08
Expected dividend yield	—		—

Share-based compensation expense by classification for the three months ended March 31, 2021 and 2020 are as follows:


	Three Months Ended
(in thousands)	March 31, 2021		March 31, 2020
Research and development	$	263	$	548
General and administrative	640		775
Total	$	903	$	1,323

At March 31, 2021, total compensation cost not yet recognized was $4.8 million and the weighted-average period over which this amount is expected to be recognized is 1.8 years.

COMMITMENTS AND CONTINGENCIES	3 Months Ended
COMMITMENTS AND CONTINGENCIES	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Co-Development and Co-Commercialization Agreement - Adaptimmune Therapeutics plc On December 16, 2016, the Company entered into a Co-Development and Co-Commercialization Agreement with and Adaptimmune Therapeutics plc (“Adaptimmune”) in order to facilitate a staged collaboration to evaluate, develop and commercialize next generation T cell therapies. Under the Agreement, the parties agreed to evaluate the Company’s GoTCR technology (inducible MyD88/CD40 co-stimulation, or “iMC”) with Adaptimmune’s affinity-optimized SPEAR® T cells for the potential to create enhanced TCR product candidates. Depending on results of the preclinical proof-of-concept phase, the parties expect to progress to a two-target co-development and co-commercialization phase. To the extent necessary, and in furtherance of the parties’ proof-of-concept and co-development efforts, the parties granted each other a royalty-free, non-transferable, non-exclusive license covering their respective technologies for purposes of facilitating such proof-of-concept and co-development efforts. In addition, as to covered therapies developed under the agreement, the parties granted each other a reciprocal exclusive license for the commercialization of such therapies. With respect to any joint commercialization of a covered therapy, the parties agreed to negotiate in good faith the commercially reasonable terms of a co-commercialization agreement. The parties also agreed that any such agreement shall provide for, among other things, equal sharing of the costs of any such joint commercialization and the calculation of profit shares as set forth in the Agreement. The Agreement will expire on a country-by-country basis once the parties cease commercialization of the T cell therapies covered by the Agreement, unless earlier terminated by either party for material breach, non-performance or cessation of development, bankruptcy/insolvency, or failure to progress to co-development phase. License Agreement - Baylor In March 2016, the Company and Baylor College of Medicine (“BCM”) entered into two additional license agreements pursuant to which the Company obtained exclusive rights to technologies and patent rights owned by BCM. The Company paid BCM a nonrefundable license fee of $100,000 and could incur additional payments upon the achievement of certain milestone events as set forth in the agreement. If the Company is successful in developing any of the licensed technologies, resulting sales would be subject to a royalty payment in the low single digits. 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 business days of the effective date of the BioVec Agreement and a fee of $300,000 within ten business days of its receipt of the first release of GMP lot of the products licensed under the BioVec Agreement. In addition, the Company agreed to pay to BioVec an annual fee of $150,000, commencing 30 days following the first filing of an Investigational New Drug Application, or its foreign equivalent, for a product covered by the license; with such annual fees being creditable against any royalties payable by the Company to BioVec under the BioVec Agreement. The Company also is required to make a $250,000 milestone payment to BioVec for each of the first three licensed products to enter into a clinical phase trial and one-time milestone payments of $2.0 million upon receipt of a registration granted by the Federal Drug Administration or European Medicines Agency on each of the Company’s first three licensed products. The BioVec Agreement additionally provides that the Company will pay to BioVec a royalty in the low single digits on net sales of products covered by the BioVec Agreement. The Company may also grant sublicensees under the licensed patent rights and know-how to third parties for limited purposes related to the use, sale and other exploitation of the products licensed under the BioVec Agreement. The BioVec Agreement will continue until terminated. The BioVec Agreement may be terminated by the Company, in its sole discretion, at any time upon 90 days written notice to BioVec. Either party may terminate the BioVec Agreement in the event of a breach by the other party of any material provision of the BioVec Agreement that remains uncured on the date that is 60 days after written notice of such failure or upon certain insolvency events that remain uncured following the date that is 30 days after the date of written notice to a party regarding such insolvency event. Litigation On May 29, 2019, Bellicum was served with a second amended complaint indicating that the Company had been added as an additional defendant in an ongoing civil tort lawsuit, captioned Kelly v. Children’s Hospital of Los Angeles et al., filed in the Los Angeles County Superior Court, Case No. BC681477. On July 10, 2019 plaintiffs filed a third amended complaint seeking unspecified monetary damages including punitive damages and alleging claims for wrongful death, negligence, breach of fiduciary duty, fraud, medical battery on decedent, medical battery on individual plaintiffs, products liability - failure to warn, breach of express warranty and products liability design or manufacturing defect. Bellicum filed a demurrer and motion to strike plaintiffs’ third amended complaint, which were granted in part on August 5, 2020 with the Court dismissing (without prejudice) all claims against Bellicum with the exception of the breach of express warranty and products liability design or manufacturing defect causes of action. The Court also granted Bellicum’s motion to strike plaintiffs’ claim for punitive damages. On September 15, 2020, plaintiffs filed a fourth amended complaint alleging the same causes of action and damages against Bellicum as were pled in the third amended complaint. On November 3, 2020 Bellicum filed a demurrer and motion to strike the fourth amended complaint, which currently is set for hearing on June 23, 2021. A trial date has not been set in the case.

SUBSEQUENT EVENTS	3 Months Ended
SUBSEQUENT EVENTS	Mar. 31, 2021
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS Takeda Supply Agreement On May 4, 2021, the Company entered a multi-year supply agreement with Takeda Development Center Americas, Inc. (Takeda). The Company is expecting revenue of $0.7 million in 2021, with the possibility of additional revenue from sales in future periods. Compliance with NASDAQ Listing Rules On May 5, 2021, the Company was notified by The Nasdaq Stock Market LLC, or Nasdaq, that the Company was in breach of Listing Rule 5450(b)(2)(A), or the Market Value Rule, for continued listing on The Nasdaq Capital Market because the market value of our listed securities for 30 consecutive business days had been less than $35 million. In accordance with Nasdaq Listing Rule 5810(c)(3)(C), the Company has until November 1, 2021, to regain compliance with the Market Value Rule. To regain compliance, the market value of the Company's listed securities must close at $35 million or more for a minimum of 10 consecutive business days any time prior to November 1, 2021.

ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

3 Months Ended

Mar. 31, 2021

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

Cash, Cash Equivalents, and Restricted Cash

Cash, Cash Equivalents and Restricted Cash

Warrant Derivatives

Private Placement Option

Preferred Stock

Operating Leases

Fair Value of Financial Instruments

Observable inputs reflect readily obtainable data from independent sources, and unobservable inputs reflect the Company’s market assumptions.

These inputs are classified into the following hierarchy:

Level 1 Inputs - quoted prices (unadjusted) in active markets for identical assets 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.

Financial Instruments and Credit Risks

Equity Issuance Costs

Net Loss and Net Loss per Share of Common Stock Attributable to Common Stockholders

Net Income (Loss) per Share of Common Stock Attributable to Common Stockholders

The following table sets forth the computation of basic and diluted earnings per share:


(in thousands, except share and per share amounts)	March 31, 2021		March 31, 2020
Net (loss) income per share - basic:
Net (loss) income	$	(11,267)	$	17,576
Less: undistributed earnings to participating securities	—		(12,084)
Net (loss) income attributed to common shareholders	$	(11,267)	$	5,492

Weighted average shares for basic net (loss) income per share	10,034,970		5,039,695
Basic net (loss) income per share	$	(1.12)	$	1.09

Net (loss) income per share - diluted:
Net (loss) income attributed to common shareholders	$	(11,267)	$	5,492

Weighted average shares for basic net (loss) income per share	10,034,970		5,039,695
Effect of dilutive securities:
Stock options and restricted stock units	—		361
Weighted average shares for diluted net (loss) income per share	10,034,970		5,040,056
Diluted net (loss) income per share	$	(1.12)	$	1.09

New Accounting Requirements and Disclosures

Fair Value Measurement

Financial Instruments – Credit Losses

Income Taxes

Investments

ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

3 Months Ended

Mar. 31, 2021

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Cash, Cash Equivalents and Restricted Cash, Reconciliation


(in thousands)	March 31, 2021		December 31, 2020
Cash and cash equivalents	$	28,082	$	35,495
Restricted cash	1,501		1,501
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$	29,583	$	36,996

Accrued Expenses and Other Liabilities

Accrued expenses and other liabilities consist of the following:


(in thousands)	March 31, 2021		December 31, 2020
Accrued payroll	$	255	$	1,029
Accrued patient treatment costs	1,345		899

Accrued manufacturing costs	24		24
Accrued professional services	404		294
Accrued lease termination fee	895		—
Accrued other	2,197		1,919
Total accrued expenses and other current liabilities	$	5,120	$	4,165

Earnings Per Share, Potentially Dilutive Securities

The following table sets forth the computation of basic and diluted earnings per share:


(in thousands, except share and per share amounts)	March 31, 2021		March 31, 2020
Net (loss) income per share - basic:
Net (loss) income	$	(11,267)	$	17,576
Less: undistributed earnings to participating securities	—		(12,084)
Net (loss) income attributed to common shareholders	$	(11,267)	$	5,492

Weighted average shares for basic net (loss) income per share	10,034,970		5,039,695
Basic net (loss) income per share	$	(1.12)	$	1.09

Net (loss) income per share - diluted:
Net (loss) income attributed to common shareholders	$	(11,267)	$	5,492

Weighted average shares for basic net (loss) income per share	10,034,970		5,039,695
Effect of dilutive securities:
Stock options and restricted stock units	—		361
Weighted average shares for diluted net (loss) income per share	10,034,970		5,040,056
Diluted net (loss) income per share	$	(1.12)	$	1.09

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share


	March 31, 2021	March 31, 2020
Common Stock Equivalents:	Number of Shares
Redeemable convertible series 1 preferred stock	452,000	—
Warrants to purchase common stock	11,616,080	—
Private placement option	9,675,000	9,675,000
Options to purchase common stock	1,400,470	1,051,665
Unvested shares of restricted stock units	262,010	4,334
Total common stock equivalents	23,405,560	10,730,999

FAIR VALUE MEASUREMENTS AND INVESTMENT SECURITIES (Tables)

3 Months Ended

Mar. 31, 2021

Fair Value Disclosures [Abstract]

Summary of Assets Measured at Fair Value on a Recurring Basis


	Fair Value at March 31, 2021						Fair Value at December 31, 2020
(in thousands)	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
Cash equivalents:
Money market funds and treasury bills	$	20,473	$	—	$	—	$	27,463	$	—	$	—
Total cash equivalents	$	20,473	$	—	$	—	$	27,463	$	—	$	—

The following table provides the warrant derivative and private placement option reported at fair value and measured on a recurring basis:


	Fair Value at March 31, 2021						Fair Value at December 31, 2020
(in thousands)	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
Warrant derivative liability	$	—	$	—	$	11,863	$	—	$	—	$	10,345
Private placement option liability	—		—		8,622		—		—		7,803
Total fair value	$	—	$	—	$	20,485	$	—	$	—	$	18,148

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:


	March 31, 2021	December 31, 2020
Risk-free interest rate	0.99%	0.46%
Volatility	95.00%	90.00%
Expected term (years)	5.39	5.64

The fair value of the private placement option has been estimated with the following weighted-average assumptions, including the most sensitive input, volatility:


	March 31, 2021		December 31, 2020
Risk-free interest rate	1.50	%	0.77	%
Volatility	95.00	%	90.00	%
Expected term (years)	7.00		7.00

The following table reflects the fair value roll forward reconciliation of the warrant derivative and private placement option liabilities for the period ended March 31, 2021:


(in thousands)	Warrant Derivative Liability		Private Placement Option Liability		Total
Balance, December 31, 2020	$	10,345	$	7,803	$	18,148
Change in fair value	1,518		819		2,337
Balance, March 31, 2021	$	11,863	$	8,622	$	20,485

LEASES (Tables)

3 Months Ended

Mar. 31, 2021

Leases [Abstract]

Components of Lease Cost

Components of lease cost are as follows:


	Three Months Ended
(in thousands)	March 31, 2021		March 31, 2020
Finance lease cost:
Amortization of leased asset	$	10	$	18
Interest on lease liabilities	4		6
Operating lease cost	54		305
Short-term lease cost	52		34
Total lease cost	$	120	$	363

PUBLIC OFFERING AND PRIVATE PLACEMENT (Tables)

3 Months Ended

Mar. 31, 2021

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:


	March 31, 2021	December 31, 2020
Risk-free interest rate	0.99%	0.46%
Volatility	95.00%	90.00%
Expected term (years)	5.39	5.64

The fair value of the private placement option has been estimated with the following weighted-average assumptions, including the most sensitive input, volatility:


	March 31, 2021		December 31, 2020
Risk-free interest rate	1.50	%	0.77	%
Volatility	95.00	%	90.00	%
Expected term (years)	7.00		7.00

The following table reflects the fair value roll forward reconciliation of the warrant derivative and private placement option liabilities for the period ended March 31, 2021:


(in thousands)	Warrant Derivative Liability		Private Placement Option Liability		Total
Balance, December 31, 2020	$	10,345	$	7,803	$	18,148
Change in fair value	1,518		819		2,337
Balance, March 31, 2021	$	11,863	$	8,622	$	20,485

SHARE-BASED COMPENSATION PLANS (Tables)

3 Months Ended

Mar. 31, 2021

Share-based Payment Arrangement [Abstract]

Stock Option Activity

The following table summarizes the stock option activity for all stock plans during the three months ended March 31, 2021:


			Options and Inducement Awards
Outstanding at December 31, 2020			1,510,968
Granted			104,000
Exercised			—
Forfeited			(214,498)
Outstanding at March 31, 2021			1,400,470
Exercisable at March 31, 2021			350,101

Restricted Stock Unit Activity

The following table summarizes the restricted stock unit award activity for all stock plans during the three months ended March 31, 2021:


			Restricted Stock Unit Awards
Outstanding at Outstanding at December 31, 2020			129,861
Granted			135,251
Vested			(596)
Forfeited			(2,506)
Outstanding at March 31, 2021			262,010

ESPP Activity

A summary of activity within the ESPP follows:


	Three Months Ended
(in thousands)	March 31, 2021		March 31, 2020
Deductions from employees	$	—	$	64
Share-based compensation expense recognized	—		25
Remaining share-based compensation expense	—		157

Valuation Assumptions

The fair value of option grants is determined using the Black-Scholes option-pricing model and has been estimated with the following weighted-average assumptions:


	Three Months Ended
	March 31, 2021		March 31, 2020
Risk-free interest rate	0.90	%	1.40	%
Volatility	90.67	%	80.69	%
Expected life (years)	5.64		6.08
Expected dividend yield	—		—

Share-Based Compensation Expense by Classification

Share-based compensation expense by classification for the three months ended March 31, 2021 and 2020 are as follows:


	Three Months Ended
(in thousands)	March 31, 2021		March 31, 2020
Research and development	$	263	$	548
General and administrative	640		775
Total	$	903	$	1,323

ORGANIZATION, BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) $ in Thousands				3 Months Ended
	Mar. 15, 2021 USD ($)	Apr. 14, 2020 USD ($)	Feb. 05, 2020 shares	Mar. 31, 2021 USD ($) subsidiaries plan shares	Dec. 31, 2020 USD ($) shares	Mar. 31, 2020 USD ($)	Mar. 26, 2021 USD ($)	Feb. 26, 2021 USD ($)	Jun. 15, 2020 shares	Jun. 14, 2020 shares	Feb. 04, 2020 shares	Dec. 31, 2019 USD ($)
Class of Stock [Line Items]
Number of wholly-owned subsidiaries formed \| subsidiaries				2
Number of reportable segments \| plan				1
Number of operating segments \| plan				1
Reverse stock split ratio			0.1
Common stock, authorized (in shares) \| shares			40,000,000	80,000,000	80,000,000				80,000,000	40,000,000	200,000,000
Accumulated deficit				$ (552,014)	$ (540,747)
Operating lease right-of-use assets				0	645
Property and equipment, net				63	189
Loss on lease termination				464		$ 0
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents				29,583	36,996	$ 75,494						$ 93,816
2130 W. Holcombe Blvd.
Class of Stock [Line Items]
Cash proceeds subject to escrow provisions		$ 1,500
Reed Road, Houston, TX
Class of Stock [Line Items]
Amount paid upon closing of asset sale								$ 1,100
Lease exit agreement, cash receivable								900
Lease exist agreement, note receivable								$ 200
San Francisco Office Space
Class of Stock [Line Items]
Operating lease right-of-use assets							$ 600
Operating lease liability							1,000
Lease termination fee	$ 900
Security deposit	$ 200
Loss on lease termination				$ 500
San Francisco Office Space \| Equipment
Class of Stock [Line Items]
Operating lease right-of-use assets							$ 100
Disposal Group, Held-for-sale, Not Discontinued Operations \| Research And Development Facility
Class of Stock [Line Items]
Operating lease right-of-use assets					500
Property and equipment, net					2,300
Operating lease liability					700
Impairment Charge on Reclassified Assets					$ 1,300

ORGANIZATION, BASIS OF PRESENTATION, AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Cash Reconciliation (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents	$ 28,082	$ 35,495
Restricted cash	1,501	1,501
Total cash, cash equivalents and restricted cash shown in the statements of cash flows	$ 29,583	$ 36,996	$ 75,494	$ 93,816

ORGANIZATION, BASIS OF PRESENTATION, AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued payroll	$ 255	$ 1,029
Accrued patient treatment costs	1,345	899
Accrued manufacturing costs	24	24
Accrued professional services	404	294
Accrued lease termination fee	895	0
Accrued other	2,197	1,919
Total accrued expenses and other current liabilities	$ 5,120	$ 4,165

ORGANIZATION AND BUSINESS DESCRIPTION - Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Net (loss) income per share - basic:
Net (loss) income	$ (11,267)	$ 17,576
Less: undistributed earnings to participating securities	0	(12,084)
Net (loss) income attributable to common shareholders	$ (11,267)	$ 5,492
Weighted average shares for basic net Loss) income per share (in shares)	10,034,970	5,039,695
Basic net (loss) income per share (in USD per share)	$ (1.12)	$ 1.09
Net (loss) income per share - diluted:
Net (loss) income attributed to common shareholders	$ (11,267)	$ 5,492
Weighted average shares for basic net Loss) income per share (in shares)	10,034,970	5,039,695
Effect of dilutive securities: Stock options and restricted stock units (in shares)	0	361
Weighted average shares for diluted net (loss) income per share (in shares)	10,034,970	5,040,056
Diluted net (loss) income per share (in USD per share)	$ (1.12)	$ 1.09

ORGANIZATION, BASIS OF PRESENTATION, AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Anti-dilutive Shares Excluded From Earnings Per Share Calculations (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Total common stock equivalents (in shares)	23,405,560	10,730,999
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)	452,000	0
Warrants to purchase common stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Total common stock equivalents (in shares)	11,616,080	0
Private placement option
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Total common stock equivalents (in shares)	9,675,000	9,675,000
Options to purchase common stock
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Total common stock equivalents (in shares)	1,400,470	1,051,665
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)	262,010	4,334

FAIR VALUE OF MEASUREMENTS AND INVESTMENT SECURITIES - Assets Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Money market funds and treasury bills
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Restricted cash equivalents	$ 1,500	$ 1,500
Level 1
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total cash equivalents	20,473	27,463
Level 1 \| Money market funds and treasury bills
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total cash equivalents	20,473	27,463
Level 2
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total cash equivalents	0	0
Level 2 \| Money market funds and treasury bills
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 and treasury bills
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Total cash equivalents	$ 0	$ 0

FAIR VALUE OF MEASUREMENTS AND INVESTMENT SECURITIES - Fair Value of Warrants (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Derivative [Line Items]
Risk-free interest rate	0.90%	1.40%
Volatility	90.67%	80.69%
Expected life (years)	5 years 7 months 20 days	6 years 29 days
Warrant Derivative Liability
Derivative [Line Items]
Risk-free interest rate	0.99%		0.46%
Volatility	95.00%		90.00%
Expected life (years)	5 years 4 months 20 days		5 years 7 months 20 days
Private Placement Option Liability
Derivative [Line Items]
Risk-free interest rate	1.50%		0.77%
Volatility	95.00%		90.00%
Expected life (years)	7 years		7 years

FAIR VALUE OF MEASUREMENTS AND INVESTMENT SECURITIES - Derivative Liabilities Reported at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	$ 11,863	$ 10,345
Private placement option derivative liability	8,622	7,803
Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	0	0
Private placement option derivative liability	0	0
Total derivative liabilities	0	0
Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	0	0
Private placement option derivative liability	0	0
Total derivative liabilities	0	0
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant derivative liability	11,863	10,345
Private placement option derivative liability	8,622	7,803
Total derivative liabilities	$ 20,485	$ 18,148

LEASES - Narrative (Details)	Mar. 31, 2021
Lessee, Lease, Description [Line Items]
Leas term option to extend	5 years
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	7 years

LEASES - Components of Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Finance lease cost:
Amortization of leased asset	$ 10	$ 18
Interest on lease liabilities	4	6
Operating lease cost	54	305
Short-term lease cost	52	34
Total lease cost	$ 120	$ 363

PUBLIC OFFERING AND PRIVATE PLACEMENT - Narrative (Details) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended
	Aug. 16, 2019	Nov. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020
Class of Stock [Line Items]
Common stock, issued (in shares)		1,040,000	8,386,019	8,385,650
Shares issuable per warrants (in shares)		3,109,378
Warrants to purchase aggregate shares of common stock (in shares)		4,149,378
Common stock, par value (in dollars per share)		$ 0.001	$ 0.01	$ 0.01
Warrant exercise price (in USD per share)		$ 6.50
Expiration period (in years)		5 years
Proceeds from issuance of stock		$ 25.0
Proceeds from issuance of redeemable convertible preferred stock in a public offering, net			$ 53.8
Proceeds upon entering into private placement agreement			11.2
Total offering costs related to warrants and options			$ 3.0
Series 1 redeemable convertible non-voting preferred stock
Class of Stock [Line Items]
Shares issuable per warrants (in shares)			10
Public Offering
Class of Stock [Line Items]
Shares issuable under warrants (in shares)	5,750,000
Price per share (in dollars per share)	$ 100.00
Public Offering \| Series 1 redeemable convertible non-voting preferred stock
Class of Stock [Line Items]
Number of shares of common stock sold in offering (in shares)	575,000
Warrants exercise price (in dollars per share)	$ 130.00
Public Offering \| Common Stock
Class of Stock [Line Items]
Shares issuable per warrants (in shares)	10
Warrants exercise price (in dollars per share)	$ 13.00
Private placement option \| Series 2 redeemable convertible non-voting preferred stock
Class of Stock [Line Items]
Number of shares of common stock sold in offering (in shares)	350,000
Shares issuable under warrants (in shares)	2,800,000
Price per share (in dollars per share)	$ 100.00
Warrants exercise price (in dollars per share)	$ 10.00
Warrants outstanding, term (in years)					2 years 6 months
Private placement option \| 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
Warrants outstanding, term (in years)						3 years
Private placement option \| Preferred Stock
Class of Stock [Line Items]
Shares issuable under warrants (in shares)	875,000
Price per share (in dollars per share)	$ 140.00
Warrants exercise price (in dollars per share)	$ 14.00
Minimum
Class of Stock [Line Items]
Price of each share of common stock and accompanying common warrant (in USD per share)		$ 6.024
Minimum \| Public Offering \| Common Stock
Class of Stock [Line Items]
Warrants, limitations on ownership after exercise			9.99%
Maximum
Class of Stock [Line Items]
Price of each share of common stock and accompanying common warrant (in USD per share)		$ 6.025
Maximum \| Public Offering \| Common Stock
Class of Stock [Line Items]
Warrants, limitations on ownership after exercise			19.99%

PUBLIC OFFERING AND PRIVATE PLACEMENT - Fair Value of Derivative Liability (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Derivatives, Fair Value [Line Items]
Change in fair value of warrant and private placement option liabilities	$ 2,337	$ (32,826)
Level 3
Derivatives, Fair Value [Line Items]
Derivative liability, fair value at date of issuance	20,485		$ 18,148
Change in fair value of warrant and private placement option liabilities	2,337
Warrant Derivative Liability \| Level 3
Derivatives, Fair Value [Line Items]
Derivative liability, fair value at date of issuance	11,863		10,345
Change in fair value of warrant and private placement option liabilities	1,518
Private Placement Option Liability \| Level 3
Derivatives, Fair Value [Line Items]
Derivative liability, fair value at date of issuance	8,622		$ 7,803
Change in fair value of warrant and private placement option liabilities	$ 819

REDEEMABLE CONVERTIBLE PREFERRED STOCK (Details) - $ / shares	Aug. 16, 2019	Mar. 31, 2021	Nov. 30, 2020	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
Shares issuable per warrants (in shares)			3,109,378
50-day trading volume on Nasdaq stock market (in shares)		50,000
Series 1 redeemable convertible non-voting preferred stock
Class of Stock [Line Items]
Preferred stock, authorized (in shares)				1,517,500
Preferred stock, outstanding (in shares)		452,000
Shares issuable per warrants (in shares)		10
Series 3 redeemable convertible non-voting preferred stock
Class of Stock [Line Items]
Closing price of common stock (in usd per share)		$ 35.00
Series 1 and 2 Preferred Stock
Class of Stock [Line Items]
Price per share (in dollars per share)		100.00
Closing price of common stock (in usd per share)		$ 25.00
Private placement option \| Series 2 redeemable convertible non-voting preferred stock
Class of Stock [Line Items]
Number of shares of common stock sold in offering (in shares)	350,000
Price per share (in dollars per share)	$ 100.00
Private placement option \| 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 option \| Preferred Stock
Class of Stock [Line Items]
Price per share (in dollars per share)	$ 140.00

SHARE-BASED COMPENSATION PLANS - Narrative (Details) $ in Millions	1 Months Ended			3 Months Ended
	Nov. 30, 2020	Jun. 30, 2020 shares	Jan. 31, 2020 shares	Mar. 31, 2021 USD ($) plan shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation plans \| plan				5
Expiration period (in years)	5 years
Compensation cost not yet recognized \| $				$ 4.8
Period for recognition				1 year 9 months 18 days
2019 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)				250,000
Additional authorized shares approved (in shares)		500,000	600,000
2019 Equity Incentive Plan \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)			600,540
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)				4 years
Expiration period (in years)				10 years
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Discount rate from grant date fair market value				15.00%
Shares available for issuance under ESPP (in shares)				18,488
ESPP \| 2014 Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)				55,000

SHARE-BASED COMPENSATION PLANS - Stock Option Activity (Details) - Employee Stock Options And Inducement Option Awards	3 Months Ended
	Mar. 31, 2021 shares
Options and Inducement awards
Outstanding at beginning of period (in shares)	1,510,968
Granted (in shares)	104,000
Exercised (in shares)	0
Forfeited (in shares)	(214,498)
Outstanding at end of period (in shares)	1,400,470
Exercisable (in shares)	350,101

SHARE-BASED COMPENSATION PLANS - Stock Award Activity For All Stock Plans (Details) - Restricted Stock Unit Awards	3 Months Ended
	Mar. 31, 2021 shares
Restricted Stock Awards and Units
Beginning balance (in shares)	129,861
Granted (in shares)	135,251
Vested (in shares)	(596)
Forfeited (in shares)	(2,506)
Ending balance (in shares)	262,010

SHARE-BASED COMPENSATION PLANS - ESPP Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense recognized	$ 903	$ 1,323
Remaining share-based compensation expense	903	1,323
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deductions from employees	0	64
Share-based compensation expense recognized	0	25
Remaining share-based compensation expense	$ 0	$ 157

SHARE-BASED COMPENSATION PLANS - Valuation Assumptions (Details)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Payment Arrangement [Abstract]
Risk-free interest rate	0.90%	1.40%
Volatility	90.67%	80.69%
Expected life (years)	5 years 7 months 20 days	6 years 29 days
Expected dividend yield	0.00%	0.00%

SHARE-BASED COMPENSATION PLANS - Expense by Classification (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense recognized	$ 903	$ 1,323
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense recognized	263	548
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense recognized	$ 640	$ 775

COMMITMENTS AND CONTINGENCIES (Details) - Licensing Agreements			1 Months Ended
	Dec. 10, 2015 USD ($)	Jun. 10, 2015 USD ($) product	Mar. 31, 2016 USD ($)
Baylor
Loss Contingencies [Line Items]
Nonrefundable license fee			$ 100,000
Agensys, Inc.
Loss Contingencies [Line Items]
Nonrefundable upfront fee	$ 3,000,000.0
Milestone payments upon first achievement of specified clinical milestones	5,000,000.0
Milestone payments upon achievement of specified clinical milestones for each licensed product	50,000,000.0
Milestone payments upon achievement of sales milestones	75,000,000.0
Option exercise fee	5,000,000.0
Milestone payments reduced upon exercise of option	$ 65,000,000.0
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
Loss Contingencies [Line Items]
Nonrefundable upfront fee		$ 100,000
Milestone payments upon first achievement of specified clinical milestones		$ 250,000
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		$ 300,000
License costs due upon first release of product, period of payment		10 days
License agreement, annual fee		$ 150,000
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		$ 2,000,000.0
Termination notice period for any other breach		90 days
Termination period, after insolvency event		30 days

SUBSEQUENT EVENTS (Details) $ in Millions	12 Months Ended
SUBSEQUENT EVENTS (Details) $ in Millions	Dec. 31, 2021 USD ($)
Forecast \| Takeda Supply Agreement
Subsequent Event [Line Items]
Revenues	$ 0.7

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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+ Details