Fortress Biotech (FBIO) 10-Q10 May 192019 Q1 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2019	May 08, 2019
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Registrant Name	Fortress Biotech, Inc.
Entity Central Index Key	0001429260
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Trading Symbol	FBIO
Entity Common Stock, Shares Outstanding		65,230,630
Entity Emerging Growth Company	false
Entity Small Business	true

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents	$ 116,444	$ 65,508
Accounts receivable	8,022	5,498
Short-term investments (certificates of deposit)	5,044	17,604
Inventory	629	678
Other receivables - related party	2,129	2,095
Prepaid expenses and other current assets	4,281	6,735
Current assets held for sale		13,089
Total current assets	136,549	111,207
Property and equipment, net	11,833	12,019
Operating lease right-of-use asset, net	22,618
Restricted cash	16,074	16,074
Long-term investment, at fair value	11,056
Intangible asset	1,183	1,417
Other assets	1,225	276
Total assets	200,538	140,993
Current liabilities
Accounts payable and accrued expenses	37,073	34,067
Accounts payable and accrued expenses - related party	16	149
Interest payable	1,013	1,232
Interest payable - related party	97	97
Notes payable, short-term - related party (net of debt discount of $223 and $336 at March 31, 2019 and December 31, 2018, respectively)	9,277	9,164
Partner company convertible note, short-term, at fair value		9,914
Operating lease liabilities – short-term	1,481
Derivative warrant liability		991
Total current liabilities	48,957	55,614
Notes payable, long-term (net of debt discount of $6,385 and $4,567 at March 31, 2019 and December 31, 2018, respectively)	73,607	60,425
Operating lease liabilities – long-term	24,989
Other long-term liabilities	2,276	5,211
Total liabilities	149,829	121,250
Stockholders' equity
Preferred stock, $.001 par value, 15,000,000 authorized, 5,000,000 designated Series A shares, 1,000,000 shares issued and outstanding as of March 31, 2019 December 31, 2018; liquidation value of $25.00 per share	1	1
Common stock, $.001 par value, 100,000,000 shares authorized, 63,126,521 and 57,845,447 shares issued and outstanding as of March 31, 2019 and December 31, 2018, respectively	63	58
Common stock issuable, 475,225 and 744,332 shares as of March 31, 2019 and December 31, 2018, respectively	765	659
Additional paid-in-capital	414,870	397,408
Accumulated deficit	(394,882)	(396,274)
Total stockholders' equity attributed to the Company	20,817	1,852
Non-controlling interests	29,892	17,891
Total stockholders' equity	50,709	19,743
Total liabilities and stockholders' equity	$ 200,538	$ 140,993

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument, Unamortized Discount, Current	$ 223	$ 336
Debt Instrument, Unamortized Discount, Noncurrent	$ 6,385	$ 4,567
Preferred Stock, par value	$ 0.001	$ 0.001
Preferred Stock, shares authorized	15,000,000	15,000,000
Preferred Stock Shares Designated	5,000,000	5,000,000
Preferred Stock, shares issued	1,000,000	1,000,000
Preferred Stock, shares outstanding	1,000,000	1,000,000
Preferred Stock, Liquidation Preference Per Share	$ 25	$ 25
Common Stock, par value	$ 0.001	$ 0.001
Common Stock, shares authorized	100,000,000	100,000,000
Common Stock, shares issued	63,126,521	57,845,447
Common Stock, shares outstanding	63,126,521	57,845,447
Common Stock, Shares Subscribed but Unissued	475,225	744,332

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue
Product revenue, net	$ 6,125	$ 5,509
Revenue - from a related party	352	394
Net revenue	6,477	5,903
Operating expenses
Cost of goods sold - product revenue	1,884	1,472
Research and development	23,273	24,958
Research and development - licenses acquired	450	97
General and administrative	13,478	13,548
Total operating expenses	39,085	40,075
Loss from operations	(32,608)	(34,172)
Other income (expenses)
Interest income	438	278
Interest expense and financing fee	(2,469)	(2,403)
Change in fair value of derivative liability	0	23
Change in fair value of subsidiary convertible note	0	250
Change in fair value of investments	0	(118)
Gain on deconsolidation of Caelum	18,384	0
Total other income (expense)	16,353	(1,970)
Loss from continuing operations	(16,255)	(36,142)
Discontinued operations
Loss from discontinued operations, net of tax	0	(2,076)
Total loss from discontinued operations	0	(2,076)
Net loss	(16,255)	(38,218)
Less: net loss attributable to non-controlling interests	17,647	17,200
Net income (loss) attributable to common stockholders	$ 1,392	$ (21,018)
Loss from continuing operations per common share - basic and diluted	$ (0.34)	$ (0.85)
Loss from discontinued operations per common share - basic and diluted	0	(0.05)
Net income (loss) per common share attributable to common stockholders - basic	0.03	(0.49)
Net income (loss) per common share attributable to common stockholders - diluted	$ 0.02	$ (0.49)
Weighted average common shares outstanding - basic	48,506,994	42,518,403
Weighted average common shares outstanding - diluted	63,811,136	42,518,403

Condensed Consolidated Statemen

Condensed Consolidated Statement of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Series A Preferred Stock [Member]	Common Stock [Member]	Shares Issuable [Member]	Paid-In Capital [Member]	Accumulated Deficit [Member]	Non-Controlling Interests [Member]
Balance at Dec. 31, 2017	$ 120,502	$ 1	$ 51	$ 500	$ 364,148	$ (312,127)	$ 67,929
Balance (in shares) at Dec. 31, 2017		1,000,000	50,991,285
Stock-based compensation expense	4,795	$ 0	$ 0	0	4,795	0	0
Issuance of restricted stock	0	$ 0	$ 1	0	(1)	0	0
Issuance of restricted stock (in shares)		0	1,472,440
Issuance of subsidiaries' common shares for license expenses	22	$ 0	$ 0	0	22	0	0
Subsidiary's offering, net	20,844	0	0	0	20,844	0	0
Exercise of subsidiary's warrants for cash	96	0	0	0	96	0	0
Issuance of common stock for at-the-market offering, net	318	0	$ 0	0	318	0	0
Issuance of common stock for at-the-market offering, net (in shares)			64,797
At-the-market offering cost	(6)	0	$ 0	0	(6)	0	0
Preferred A dividends declared and paid	(586)	0	0	0	(586)	0	0
Common shares issuable for 2017 Subordinated Note Financing interest expense	489	0	0	489	0	0	0
Common shares issued for 2017 Subordinated Note Financing interest expense	0	$ 0	$ 0	(500)	500	0	0
Common shares issued for 2017 Subordinated Note Financing interest expense (in shares)		0	158,015
–Disposal of National	(710)	$ 0	$ 0	0	(710)	0	0
Non-controlling interest in subsidiaries	0	0	0	0	(15,166)	0	15,166
Net loss attributable to non-controlling interest	(17,200)	0	0	0	0	0	(17,200)
Net income (loss) attributable to common stockholders	(21,018)	0	0	0	0	(21,018)	0
Balance at Mar. 31, 2018	107,546	$ 1	$ 52	489	374,254	(333,145)	65,895
Balance (in shares) at Mar. 31, 2018		1,000,000	52,686,537
Balance at Dec. 31, 2017	120,502	$ 1	$ 51	500	364,148	(312,127)	67,929
Balance (in shares) at Dec. 31, 2017		1,000,000	50,991,285
Net loss attributable to non-controlling interest	(57,789)
Balance at Dec. 31, 2018	19,743	$ 1	$ 58	659	397,408	(396,274)	17,891
Balance (in shares) at Dec. 31, 2018		1,000,000	57,845,447
Stock-based compensation expense	3,309	$ 0	$ 0	0	3,309	0	0
Issuance of restricted stock	0	$ 0	$ 2	0	(2)	0	0
Issuance of restricted stock (in shares)		0	1,609,325
Issuance of subsidiaries' common shares for license expenses	0	$ 0	$ 0	(164)	164	0	0
Issuance of common stock for at-the-market offering, net	6,142	0	$ 3	0	6,139	0	0
Issuance of common stock for at-the-market offering, net (in shares)			2,927,427
Preferred A dividends declared and paid	(586)	0	$ 0	0	(586)	0	0
Partner company's sale of stock, net	31,499	0	0	0	31,499	0	0
Partner company's at-the-market offering, net	355	0	0	0	355	0	0
Issuance of partner company warrants in conjunction with Horizon Notes	888				888
Common shares issuable for 2017 Subordinated Note Financing interest expense	484	0	0	484	0	0	0
Common shares issued for 2017 Subordinated Note Financing interest expense	0	$ 0	$ 0	(495)	495	0	0
Common shares issued for 2017 Subordinated Note Financing interest expense (in shares)		0	744,322
Common shares issuable for Opus interest expense	281	$ 0	$ 0	281	0	0	0
Common shares issuable for Opus interest expense (in shares)		0	0
Non-controlling interest in subsidiaries	0	$ 0	$ 0	0	(24,799)	0	24,799
Deconsolidation of Caelum non-controlling interest	4,849	0	0	0	0	0	4,849
Net loss attributable to non-controlling interest	(17,647)	0	0	0	0	0	(17,647)
Net income (loss) attributable to common stockholders	1,392	0	0	0	0	1,392	0
Balance at Mar. 31, 2019	$ 50,709	$ 1	$ 63	$ 765	$ 414,870	$ (394,882)	$ 29,892
Balance (in shares) at Mar. 31, 2019		1,000,000	63,126,521

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flows from Operating Activities:
Net loss	$ (16,255)	$ (38,218)
Net loss on discontinued operations	0	(2,076)
Loss from continuing operations	(16,255)	(36,142)
Reconciliation of net loss to net cash used in operating activities:
Depreciation expense	481	196
Amortization of debt discount	622	661
Amortization of product revenue license fee	234	133
Amortization of operating lease right-of-use assets	381
Stock-based compensation expense	3,309	4,795
Common shares issuable for Opus interest expense	281
Common shares issuable for 2017 Subordinated Note Financing interest expense	484	489
Change in fair value of investments	0	118
Change in fair value of derivative liability		(23)
Change in fair value of partner company convertible note	0	(250)
Gain on deconsolidation of Caelum	(18,384)
Research and development-licenses acquired, expense	450	97
Increase (decrease) in cash and cash equivalents resulting from changes in operating assets and liabilities:
Accounts receivable	(2,524)	(556)
Inventory	49	(51)
Other receivables - related party	(34)	(326)
Prepaid expenses and other current assets	2,483	(1,466)
Other assets	(949)	(343)
Current assets held for sale		(3,383)
Noncurrent assets held for sale		427
Current liabilities held for sale		4,040
Accounts payable and accrued expenses	3,664	6,195
Accounts payable and accrued expenses - related party	(133)	(98)
Interest payable	(21)	17
Interest payable - related party		(12)
Lease liabilities	(351)
Other long-term liabilities	888	19
Net cash used in continuing operating activities	(25,325)	(25,463)
Net cash used in discontinued operating activities		(2,381)
Net cash used in operating activities	(25,325)	(27,844)
Cash Flows from Investing Activities:
Purchase of research and development licenses		(75)
Purchase of property and equipment	(300)	(765)
Purchase of short-term investment (certificates of deposit)		(25,000)
Redemption of short-term investment (certificates of deposit)	12,560	24,000
Deconsolidation of Caelum	(1,201)
Net cash provided by (used in) continuing investing activities	11,059	(1,840)
Net cash provided by discontinued investing activities	13,089
Net cash provided by (used in) investing activities	24,148	(1,840)
Cash Flows from Financing Activities:
Payment of Preferred A dividends	(586)	(586)
Inter-company costs related to the issuance of Series A preferred stock		1,298
Proceeds from at-the-market offering	6,251	229
Payment of cost related to at-the-market offering	(109)	(6)
Proceeds from partner company's sale of stock	34,999	23,011
Payment of costs related to partner company's sale of stock	(3,500)	(2,167)
Proceeds from partner company's at-the-market offering	366
Payment of costs related to partner company's at-the-market offering	(11)
Proceeds from exercise of partner companies' warrants		96
Payment of debt issuance costs associated with 2017 Subordinated Note Financing		(255)
Proceeds from 2018 Venture Notes		21,707
Payment of debt issue costs associated with 2018 Venture Notes	(67)	(1,814)
Proceeds from partner company's Horizon Notes	15,000
Payment of debt issuance costs associated with partner company's Horizon Notes	(230)
Payment of partner company's Convertible Notes		(1,858)
Net cash provided by financing activities	52,113	39,655
Net increase in cash and cash equivalents and restricted cash	50,936	9,971
Cash and cash equivalents and restricted cash at beginning of period	81,582	110,958
Cash and cash equivalents and restricted cash at end of period	132,518	120,929
Supplemental disclosure of cash flow information:
Cash paid for interest	1,100	394
Cash paid for interest - related party		853
Supplemental disclosure of non-cash financing and investing activities:
Settlement of restricted stock units into common stock	2	1
Receivable from ATM issuances		89
Unpaid debt offering costs	1,202
Common shares issuable for license acquired	164
Common shares issued for 2017 Subordinated Note Financing interest expense	495	500
Issuance of partner company warrants in conjunction with Horizon Notes	888
Unpaid fixed assets	191	2,321
Inter-company costs related to the issuance of Series A preferred stock		$ 1,298

Organization and Description of

Organization and Description of Business	3 Months Ended
Organization and Description of Business	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	1. Organization and Description of Business Fortress Biotech, Inc. (“Fortress” or the “Company”) is a biopharmaceutical company dedicated to acquiring, developing and commercializing pharmaceutical and biotechnology products and product candidates, which the Company does at the Fortress level, at its majority-owned and majority-controlled subsidiaries and joint ventures, and at entities the Company founded and in which it maintains significant minority ownership positions. Fortress has a talented and experienced business development team, comprising scientists, doctors and finance professionals, who identify and evaluate promising products and product candidates for potential acquisition by new or existing partner companies. Fortress through its partner companies has executed such arrangements in partnership with some of the world’s foremost universities, research institutes and pharmaceutical companies, including City of Hope National Medical Center, St. Jude Children’s Research Hospital and University College London. Following the exclusive license or other acquisition of the intellectual property underpinning a product or product candidate, Fortress leverages its business, scientific, regulatory, legal and finance expertise to help the partners achieve their goals. Partner companies then assess a broad range of strategic arrangements to accelerate and provide additional funding to support research and development, including joint ventures, partnerships, out-licensings, and public and private financings; to date, three partner companies are publicly-traded, and two have consummated strategic partnerships with industry leaders Alexion Pharmaceuticals, Inc. and InvaGen Pharmaceuticals, Inc. (a subsidiary of Cipla Limited). As of March 31, 2019, several of the Fortress partner companies maintain licenses to product candidate intellectual property, including Aevitas Therapeutics, Inc. (“Aevitas”), Avenue Therapeutics, Inc. (“Avenue”), Caelum Biosciences, Inc. (“Caelum”), Cellvation, Inc. (“Cellvation”), Checkpoint Therapeutics, Inc. (“Checkpoint”), Cyprium Therapeutics, Inc. (“Cyprium”), Helocyte, Inc. (“Helocyte”), Journey Medical Corporation (“Journey” or “JMC”), Mustang Bio, Inc. (“Mustang”), and Tamid Bio, Inc. (“Tamid”). Liquidity and Capital Resources Since inception, the Company’s operations have been financed primarily through the sale of equity and debt securities and proceeds from the exercise of warrants and stock options. The Company has incurred losses from operations and negative cash flows from operating activities since inception and expects to continue to incur substantial losses for the next several years as it continues to fully develop and prepare regulatory filings and obtain regulatory approvals for its existing and new product candidates. The Company’s current cash and cash equivalents are sufficient to fund operations for at least the next 12 months. However, the Company will need to raise additional funding through strategic relationships, public or private equity or debt financings, sale of a partner company, grants or other arrangements to fully develop and prepare regulatory filings and obtain regulatory approvals for the existing and new product candidates, fund operating losses, and, if deemed appropriate, establish or secure through third parties manufacturing for the potential products, sales and marketing capabilities. If such funding is not available or not available on terms acceptable to the Company, the Company’s current development plan and plans for expansion of its general and administrative infrastructure will be curtailed.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, the unaudited interim condensed consolidated financial statements reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the balances and results for the periods presented. Certain information and footnote disclosures normally included in the Company’s annual financial statements prepared in accordance with GAAP have been condensed or omitted. These condensed consolidated financial statement results are not necessarily indicative of results to be expected for the full fiscal year or any future period. The unaudited condensed consolidated financial statements and related disclosures have been prepared with the presumption that users of the unaudited condensed consolidated financial statements have read or have access to the audited financial statements for the preceding fiscal year for each of the companies: Avenue, Checkpoint and Mustang. Accordingly, these unaudited condensed consolidated financial statements should be read in conjunction with the Company’s Form 10-K, which was filed with the United States Securities and Exchange Commission (“SEC”) on March 18, 2019, from which the Company derived the balance sheet data at December 31, 2018, as well as Checkpoint’s Form 10-K filed with the SEC on March 18, 2019, Mustang’s Form 10-K, filed with the SEC on March 18, 2019, and Avenue’s Form 10-K, filed with the SEC on March 12, 2019. The Company’s unaudited condensed consolidated financial statements include the accounts of the Company and its subsidiaries: Avenue, Aevitas, CB Securities Corporation, Cellvation, Coronado SO Co., Checkpoint, Cyprium, Escala Therapeutics, Inc., GeneXion Oncology, Inc., Helocyte, Immune Limited, JMC, Mustang, Tamid, Fortress Biotech China, Inc., FBIO Acquisition Corp. IV, FBIO Acquisition Corps. VI - XIV, and JG Pharma, Inc., a subsidiary of JMC. All intercompany balances and transactions have been eliminated. The preparation of the Company’s unaudited condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the unaudited condensed consolidated financial statements and the reported amounts of expenses during the reporting period. Use of Estimates The Company’s unaudited condensed consolidated financial statements include certain amounts that are based on management’s best estimates and judgments. The Company’s significant estimates include, but are not limited to, useful lives assigned to long-lived and intangible assets, fair value measurements, stock-based compensation, common stock issued to acquire licenses, investments, accrued expenses, derivative warrant liabilities, revenue with customers, provisions for income taxes and contingencies. Due to the uncertainty inherent in such estimates, actual results may differ from these estimates. Discontinued Operations At December 31, 2018, the Company determined that its National segment met the discontinued operations criteria set forth in Accounting Standards Codification (ASC) Subtopic 205-20-45, Presentation of Financial Statements Consolidated Statements of Operations. See Note 3 for more information relating to the Company’s discontinued operations. Significant Accounting Policies There have been no material changes in the Company’s significant accounting policies to those previously disclosed in the 2018 Annual Report other than the adoption of the Financial Accounting Standards Board (FASB) Accounting Standard Updates (ASU) ASU 2016-02, Leases, and 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting . Leases Effective January 1, 2019, the Company accounts for its leases under ASC 842, Leases . Under this guidance, arrangements meeting the definition of a lease are classified as operating or financing leases, and are recorded on the condensed consolidated balance sheet as both a right-of-use asset and lease liability, calculated by discounting fixed lease payments over the lease term at the rate implicit in the lease or the Company’s incremental borrowing rate. Lease liabilities are increased by interest and reduced by payments each period, and the right-of-use asset is amortized over the lease term. For operating leases, interest on the lease liability and the amortization of the right-of-use asset result in straight-line rent expense over the lease term. For finance leases, interest on the lease liability and the amortization of the right-of-use asset results in front-loaded expense over the lease term. Variable lease expenses are recorded when incurred. In calculating the right-of-use asset and lease liability, the Company elects to combine lease and non-lease components. The Company continues to account for leases in the prior period financial statements under ASC Topic Stock-Based Compensation The Company expenses stock-based compensation to employees over the requisite service period based on the estimated grant-date fair value of the awards and forfeiture rates. For stock-based compensation awards to non-employees, prior to the adoption of ASU 2018-07 on January 1, 2019, the Company remeasured the fair value of the non-employee awards at each reporting period prior to vesting and finally at the vesting date of the award. Changes in the estimated fair value of these non-employee awards were recognized as compensation expense in the period of change. Subsequent to the adoption of ASU 2018-07, the Company recognizes non-employees compensation costs over the requisite service period based on a measurement of fair value for each stock award. The Company estimates the fair value of stock option grants using the Black-Scholes option pricing model or 409A valuations, as applicable. The assumptions used in calculating the fair value of stock-based awards represent management’s best estimates and involve inherent uncertainties and the application of management’s judgment. Recently Adopted Accounting Pronouncements In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification , amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders' equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. This final rule became effective on November 5, 2018. The Company included the required presentation of changes in stockholders’ equity in this Form 10-Q. In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting financial statements. In July 2017, the FASB issued ASU 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480) and Derivatives and Hedging (Topic 815): I. Accounting for Certain Financial Instruments with Down Round Features; II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) in order to increase transparency and comparability among organizations by, among other provisions, recognizing lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under previous GAAP. For public companies, ASU 2016-02 is effective for fiscal years beginning after December 15, 2018 (including interim periods within those periods) using a modified retrospective approach and early adoption is permitted. In transition, entities may also elect a package of practical expedients that must be applied in its entirety to all leases commencing before the adoption date, unless the lease is modified, and permits entities to not reassess (a) the existence of a lease, (b) lease classification or (c) determination of initial direct costs, as of the adoption date, which effectively allows entities to carryforward accounting conclusions under previous U.S. GAAP. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements Recent Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326) : Measurement of Credit Losses on Financial Instruments. ASU 2016-13 requires that expected credit losses relating to financial assets are measured on an amortized cost basis and available-for-sale debt securities be recorded through an allowance for credit losses. ASU 2016-13 limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and also requires the reversal of previously recognized credit losses if fair value increases. The new standard will be effective on January 1, 2020 and may be adopted earlier. The Company is currently evaluating the impact, if any, that ASU 2016-13 will have on its condensed consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820), - Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement , which makes a number of changes meant to add, modify or remove certain disclosure requirements associated with the movement amongst or hierarchy associated with Level 1, Level 2 and Level 3 fair value measurements. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted upon issuance of the update. The Company does not expect the adoption of this guidance to have a material impact on its financial statements.

Discontinued Operations

Discontinued Operations	3 Months Ended
Discontinued Operations	Mar. 31, 2019
Discontinued Operations and Disposal Groups [Abstract]
Discontinued Operations	3. Discontinued Operations The following is a summary of revenue and expenses of National for the three months ended March 31, 2019 and 2018: Three months ended March 31, ($ in thousands) 2019 2018 Revenue $ – $ 49,522 Operating expenses Commissions, compensation and fees – 43,561 Clearing fees – 743 Communications – 760 Occupancy – 955 Licenses and registration – 637 Professional fees – 1,393 Underwriting costs – 145 Interest – 2 Depreciation and amortization – 859 Other administrative expenses – 1,781 Total operating expenses – 50,836 Gain (loss) from operations – (1,314 ) Other income (expenses) Change in fair value of derivative liabilities – (1,088 ) Interest expense and financing fees – 320 Interest income – 6 Total other expenses – (762 ) Total loss from discontinued operations $ – $ (2,076 ) As of March 31, 2019, the Company received $13.1 million or $3.25 per share, for its remaining ownership of National, as such as of March 31, 2019 the Company had no asset available for sale on its condensed consolidated balance sheets. In connection with this sale, the Company classified the assets and liabilities related to National, included on its condensed consolidated balance sheet as of March 31, 2019 and December 31, 2018, as held for sale as presented in the table below: March 31, December 31, ($ in thousands) 2019 2018 ASSETS Current assets Current assets held for sale $ – $ 13,089 Total current assets held for sale – 13,089 Total assets held for sale $ – $ 13,089 The table below depicts the cash flows from the transaction for the three months ended March 31, 2019 and 2018, respectively: Three months ended March 31, ($ in thousands) 2019 2018 Operating activities Effect of elimination entry on discontinued operations presentation $ – $ (305 ) Net loss on discontinued operations – (2,076 ) Total cash used in discontinued operating activities $ – $ (2,381 ) Investing activities Proceeds from sale of National $ 13,089 $ – Total cash provided by discontinued investing activities $ 13,089 $ –

Collaboration and Stock Purchas

Collaboration and Stock Purchase Agreements	3 Months Ended
Collaboration and Stock Purchase Agreements	Mar. 31, 2019
Collaboration And Stock Purchase Agreements [Abstract]
Collaboration and Stock Purchase Agreements	4. Collaboration and Stock Purchase Agreements Caelum Agreement with Alexion In January 2019, our partner company Caelum Biosciences, Inc. (“Caelum”) signed an agreement with Alexion Pharmaceuticals, Inc. (“Alexion”) to advance the development of CAEL-101. Under the terms of the agreement, Alexion purchased a 19.9% minority equity interest in Caelum for $30 million. Additionally, Alexion has agreed to make potential payments to Caelum upon the achievement of certain developmental milestones, in exchange for which Alexion obtained a contingent exclusive option to acquire the remaining equity in the company for pre-negotiated economics. In connection with the Alexion agreement, the Company deconsolidated its holdings in Caelum immediately prior to the execution of the agreement. The following table provides a summary of the assets and liabilities of Caelum impacted by the deconsolidation: January ($ in thousands) 2019 ASSETS Current assets Cash and cash equivalents $ 1,201 Prepaid expenses and other current assets 6 Total current assets held for sale $ 1,207 LIABILITIES Current liabilities Accounts payable and accrued expenses $ 2,246 Interest payable 198 Interest payable - related party 106 Note payable - related party 929 Note payable 9,914 Warrant liability 991 Other current liabilities 14,384 Net liabilities impacted by deconsolidation $ 13,177 In connection with this transaction the Company recorded a gain resulting from the deconsolidation of Caelum on its condensed consolidated financial statements for the three months ended March 31, 2019: ($ in thousands) Gain on deconsolidation of Caelum Fair value of Caelum $ 11,056 Net liabilities deconsolidated 13,177 Non-controlling interest share (4,849 ) Write off of MSA fees due Fortress (1,000 ) Gain on deconsolidation of Caelum $ 18,384 Avenue Agreement with InvaGen On November 12, 2018, the Company’s partner company Avenue entered into a Stock Purchase and Merger Agreement (“SPMA”) with InvaGen Pharmaceuticals Inc. (“InvaGen”) and Madison Pharmaceuticals Inc., a newly-formed, wholly-owned subsidiary of InvaGen. Pursuant to the SPMA, and following approval by Avenue’s stockholders on February 8, 2019, InvaGen purchased a number of shares of Avenue common stock representing 33.3% of Avenue’s fully-diluted capital stock for net proceeds to Avenue of $31.5 million (after deducting fees and other offering-related costs). Upon the achievement of certain closing conditions (including most notably U.S. Food and Drug Administration approval for IV Tramadol, Avenue’s product candidate), InvaGen will be obligated to acquire Avenue via reverse subsidiary merger (the “Merger Transaction”). Under the Merger Transaction, InvaGen will pay $180 million (subject to certain potential reductions) to the holders of Avenue’s capital stock (other than InvaGen itself). Subject to the terms and conditions described in the SPMA, InvaGen may also provide interim financing to Avenue in an amount of up to $7.0 million during the time period between February 8, 2019 and the Merger Transaction. Any amounts drawn on the interim financing will be deducted from the aggregate consideration payable to Company stockholders by virtue of the Merger Transaction. Prior to the closing of the Merger Transaction, Avenue will enter into a Contingent Value Rights Agreement (the “CVR Agreement”) with a trust company as rights, pursuant to which holders of common shares of Avenue, other than InvaGen (each, a “Holder”), will be entitled to receive on Contingent Value Right (“CVR”) for each share held immediately prior to the Merger Transaction. Each CVR represents the right of its holder to receive a contingent cash payment pursuant to the CVR Agreement upon the achievement of certain milestones. If, during the period commencing on the day following the closing of the Merger Transaction until December 31, 2028, IV Tramadol generates at least $325 million or more in Net Sales (as defined in the CVR Agreement) in a calendar year, each Holder shall entitled to receive their pro rata share of (i) if the product generated less than $400 million in Net Sales during such calendar year, 10% of Gross Profit (as defined in the CVR Agreement), (ii) if the product generated between $400 million and $500 million in Net Sales during such calendar year, 12.5% of Gross Profit, or (iii) if the product generated more than $500 million in Net Sales during such calendar year, 15% of Gross Profit. Additionally, at any time beginning on January 1, 2029 that IV Tramadol has generated at least $1.5 billion in aggregate Net Sales, then with respect to each calendar year in which IV Tramadol generates $100 million or more in Net Sales, each Holder shall be entitled to receive their pro rata share of an amount equal to 20% of the Gross Profit generated by IV Tramadol. These additional payments will terminate on the earlier of December 31, 2036 and the date (which may be extended by up to 6 months) that any person has received approval from the FDA for an Abbreviated New Drug Application or an FDA AP-rated 505(b)(2) NDA using IV Tramadol.

Property and Equipment

Property and Equipment	3 Months Ended
Property and Equipment	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Property and Equipment	5. Property and Equipment Fortress’ property and equipment consisted of the following: ($ in thousands) Useful Life (Years) March 31, 2019 December 31, 2018 Computer equipment 3 $ 648 $ 648 Furniture and fixtures 5 1,142 1,128 Machinery & equipment 5 3,242 3,143 Leasehold improvements 5 15 9,359 9,271 Construction in progress 1 N/A 487 393 Total property and equipment 14,878 14,583 Less: Accumulated depreciation (3,045 ) (2,564 ) Property and equipment, net $ 11,833 $ 12,019 Note 1: Relates to the Mustang cell processing facility. Fortress' depreciation expense for the three months ended March 31, 2019 and 2018, was approximately $0.5 million and $0.2 million, respectively, and was recorded in both research and development expense and general and administrative expense in the Condensed Consolidated Statements of Operations.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
Fair Value Measurements	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value Measurements	6. Fair Value Measurements Certain of the Company’s financial instruments are not measured at fair value on a recurring basis but are recorded at amounts that approximate their fair value due to their liquid or short-term nature, such as accounts payable, accrued expenses and other current liabilities. Fair Value of Caelum The Company valued its investment in Caelum in accordance with ASC Topic 820, Fair Value Measurements and Disclosures The following inputs were utilized to derive the value: risk free rate of return of 2.24%, volatility of 70% and a discount for lack of marketability of 27.9%. In connection with the DOSPA Caelum’s convertible notes automatically converted into common shares of Caelum and the warrant liability payable to the placement agent in connection with the placement of the convertible notes was also issued. Caelum Warrant liability The Caelum warrant liability and convertible notes did not exist as of March 31, 2019. A summary of the weighted average (in aggregate) significant unobservable inputs (Level 3 inputs) used in measuring Caelum’s warrant liability that are categorized within Level 3 of the fair value hierarchy as of December 31, 2018 is as follows: December 31, 2018 Risk-free interest rate 2.905 2.909 % Expected dividend yield – % Expected term in years 3.84 3.96 Expected volatility 70 % ($ in thousands) Fair Value of Derivative Warrant Liability Beginning balance at January 1, 2019 $ 991 Issuance of warrant due to conversion of note (991 ) Ending balance at March 31, 2019 $ – Caelum Convertible Notes A summary of the weighted average (in aggregate) significant unobservable inputs (Level 3 inputs) used in measuring Caelum’s convertible notes that are categorized within Level 3 of the fair value hierarchy as of December 31, 2018 is as follows: December 31, 2018 Risk-free interest rate 2.302 % Expected dividend yield – % Expected term in years 0.32 Expected volatility 67 % ($ in thousands) Caelum Convertible Notes, at fair value Beginning balance at January 1, 2019 $ 9,914 Conversion of the convertible notes (9,914 ) Ending balance at March 31, 2019 $ – The following tables classify into the fair value hierarchy of Fortress’ financial instruments, measured at fair value as of March 31, 2019 and December 31, 2018: Fair Value Measurement as of March 31, 2019 ($ in thousands) Level 1 Level 2 Level 3 Total Assets Fair value of investment in Caelum $ – $ – $ 11,056 $ 11,056 Total $ – $ – $ 11,056 $ 11,056 Fair Value Measurement as of December 31, 2018 ($ in thousands) Level 1 Level 2 Level 3 Total Liabilities Caelum warrant liability $ – $ – $ 991 $ 991 Caelum convertible notes, at fair value – – 9,914 9,914 Total $ – $ – $ 10,905 $ 10,905 The table below provides a roll-forward of the changes in fair value of Level 3 financial instruments as of March 31, 2019: Caelum ($ in thousands) Convertible Note Warrant liability Total Balance at December 31, 2018 $ 9,914 $ 991 $ 10,905 Conversion of convertible notes (9,914 ) – (9,914 ) Issuance of warrant – (991 ) (991 ) Balance at March 31, 2019 $ – $ – $ – As of March 31, 2019, no transfers occurred between Level 1, Level 2 and Level 3 instruments.

Licenses Acquired

Licenses Acquired	3 Months Ended
Licenses Acquired	Mar. 31, 2019
Licenses Acquired [Abstract]
Licenses Acquired	7. Licenses Acquired In accordance with ASC 730-10-25-1, Research and Development , costs incurred in obtaining technology licenses are charged to research and development expense if the technology licensed has not reached technological feasibility and has no alternative future use. The licenses purchased by Fortress, Aevitas, Avenue, Cellvation, Checkpoint, Cyprium, Helocyte, Mustang and Tamid require substantial completion of research and development, and regulatory and marketing approval efforts in order to reach technological feasibility. As such, for the three months ended March 31, 2019 and 2018, the purchase price of licenses acquired was classified as research and development-licenses acquired in the Condensed Consolidated Statements of Operations as reflected in the table below: For the Three Months Ended March 31, ($ in thousands) 2019 2018 Partner companies: Helocyte $ – $ 21 Mustang 450 75 Cellvation – 1 Total $ 450 $ 97 Mustang In February 2019, Mustang announced that it partnered and entered into an exclusive worldwide license agreement with Nationwide Children’s Hospital (“Nationwide”) to develop the C134 oncolytic virus (MB-108) for the treatment of glioblastoma multiforme (“GBM”). Mustang intends to combine MB-108 with MB-101 (IL13R2-specific CAR) to potentially enhance efficacy in treating GBM. Mustang paid $0.2 $152.8 For the three months ended March 31, 2019 and 2018, Mustang recorded the following expense in research and development for licenses acquired: For the Three Months Ended March 31, ($ in thousands) 2019 2018 City of Hope (COH) – CD123 $ 250 $ – City of Hope manufacturing – 75 Nationwide Children’s Hospital – C134 (MB-108) 200 – Total $ 450 $ 75

Intangibles, net

Intangibles, net	3 Months Ended
Intangibles, net	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangibles, net	9. Intangibles, net The table below provides a summary of the JMC intangible asset as of March 31, 2019 and December 31, 2018, respectively: Estimated Useful March 31, December 31, ($ in thousands) Lives (in years) 2019 2018 Ceracade® 3 $ 300 $ 300 Luxamend® 3 50 50 Targadox® 3 1,250 1,250 Exelderm® 3 1,200 1,200 Total 2,800 2,800 Accumulated amortization 1,617 1,383 Net intangible assets $ 1,183 $ 1,417 The table below provides a summary for the three months ended March 31, 2019, of JMC recognized expense related to its product licenses, which was recorded in costs of goods sold on the Condensed Consolidated Statement of Operations: ( $ in thousands) Intangible Assets Beginning balance at January 1, 2019 $ 1,417 Amortization expense (234 ) Ending balance at March 31, 2019 $ 1,183 The future amortization of these intangible assets is as follows: Total ($ in thousands) Ceracade® Targadox® Exelderm® Amortization For the nine-months ending December 31, 2019 $ 8 $ 208 $ 300 $ 516 December 31, 2020 – – 400 400 December 31, 2021 – – 267 267 Total $ 8 $ 208 $ 967 $ 1,183

Debt and Interest

Debt and Interest	3 Months Ended
Debt and Interest	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt and Interest	10. Debt and Interest Debt Total debt consists of the following as of March 31, 2019 and December 31, 2018: ($ in thousands) March 31, 2019 December 31, 2018 Interest rate Maturity IDB Note $ 14,929 $ 14,929 2.25 % Aug - 2020 2017 Subordinated Note Financing 3,254 3,254 8.00 % March - 2020 2017 Subordinated Note Financing 13,893 13,893 8.00 % May - 2020 2017 Subordinated Note Financing 1,820 1,820 8.00 % June - 2020 2017 Subordinated Note Financing 3,018 3,018 8.00 % August - 2020 2017 Subordinated Note Financing 6,371 6,371 8.00 % September - 2020 2018 Venture Debt 6,517 6,517 8.00 % February - 2021 2018 Venture Debt 15,190 15,190 8.00 % March - 2021 Opus Credit Facility 1 9,500 9,500 12.00 % September - 2019 Mustang Horizon Notes 2 15,000 – 9.00 % October - 2022 Caelum Convertible Note, at fair value 1 – 1,000 8.00 % January - 2019 Caelum Convertible Note, at fair value 1 – 6,800 8.00 % February - 2019 Caelum Convertible Note, at fair value 1 – 2,114 8.00 % March - 2019 Total notes payable 89,492 84,406 Less: Discount on notes payable 6,608 4,903 Total notes payable $ 82,884 $ 79,503 Note 1: Classified as short-term on the Company’s Consolidated Balance Sheet as of December 31, 2018. Note 2: Interest rate is 9.0% plus one-month LIBOR Rate 2.5 Mustang Horizon Notes On March 29, 2019, Mustang entered into a $20.0 million venture debt financing agreement (the “Loan Agreement”) with Horizon Technology Finance Corporation (“Horizon”), the proceeds of which will provide Mustang with additional working capital to continue development of its gene and cell therapies. In accordance with the Loan Agreement, $15.0 million of the $20.0 million loan was funded on the Closing Date, with the remaining $5.0 million fundable upon Mustang achieving certain predetermined milestones. Each advance under the Horizon Loan Agreement will mature 42 months from the first day of the month following the funding of the advance. The first three advances will mature on October 1, 2022 (the “Loan Maturity Date”). Each advance accrues interest at a per annum rate of interest equal to 9.00% plus the amount by which the one-month LIBOR Rate 2.50 At its option, upon ten business days’ prior written notice to Horizon, Mustang may prepay all or any portion greater than or equal to $500,000 of each of the outstanding advances by paying the entire principal balance (or portion thereof) and all accrued and unpaid interest, subject to a prepayment charge of 4.0% of the then outstanding principal balance of each advance if such advance is prepaid on or before the Loan Amortization Date (as defined in the Loan Agreement), 3% if such advance is prepaid after the Loan Amortization Date applicable to such Loan, but on or prior to twelve months following the Loan Amortization Date, and 2% thereafter. In addition, a final payment equal to $0.3 million for each advance (i.e., $0.8 million in aggregate with respect to the initial $15.0 million) is due on the maturity date or other date of payment in full. Amounts outstanding during an event of default shall be payable on demand and shall accrue interest at an additional rate of 5.0% per annum of the past due amount outstanding. Each advance of the loan is secured by a lien on substantially all of the assets of Mustang, other than Intellectual Property and Excluded Collateral (in each case as defined in the Loan Agreement), and contains customary covenants and representations, including a liquidity covenant, financial reporting covenant and limitations on dividends, indebtedness, collateral, investments, distributions, transfers, mergers or acquisitions, taxes, corporate changes, deposit accounts, and subsidiaries. The events of default under the Loan Agreement include, among other things, without limitation, and subject to customary grace periods, (1) Mustang’s failure to make any payments of principal or interest under the Loan Agreement, promissory notes or other loan documents, (2) Mustang’s breach or default in the performance of any covenant under the Loan Agreement, (3) the occurrence of a material adverse change, (4) Mustang making a false or misleading representation or warranty in any material respect, (5) Mustang’s insolvency or bankruptcy, (6) certain attachments or judgments on the Mustang’s assets, (7) the occurrence of any material default under certain agreements or obligations of Mustang involving indebtedness in excess of $0.3 million or (8) failing to maintain minimum monthly cash balances which range from approximately $8.0 to $13.0 million over the term of the loan. If an event of default occurs, Horizon is entitled to take enforcement action, including acceleration of amounts due under the Loan Agreement. The Loan Agreement also contains warrant coverage of 5% of the total amount Four warrants (the “Warrants”) were issued by Mustang to Horizon to purchase a combined 288,184 The Warrant is exercisable for ten years from the date of issuance. Horizon may exercise the Warrant either by (a) cash or check or (b) through a net issuance conversion. The shares of Mustang’s common stock will, upon request by Horizon, be registered and freely tradeable following a period of six months after issuance. Mustang paid Horizon an initial commitment fee of $0.2 million and reimbursed Horizon for $30,000 of legal fees in connection with the Loan Agreement. Mustang incurred approximately $1.2 million of legal and other direct costs incurred in connection with the Loan Agreement. All fees, and costs paid to Horizon and all direct costs incurred by Mustang are recognized as a debt discount to the funded loans and are amortized to interest expense using the effective interest method over the term of the Loan Agreement. Interest Expense The following table shows the details of interest expense for all debt arrangements during the periods presented. Interest expense includes contractual interest and amortization of the debt discount and amortization of fees represents fees associated with loan transaction costs, amortized over the life of the loan: Three Months Ended March 31, 2019 2018 ($ in thousands) Interest Fees 1 Total Interest Fees 1 Total IDB Note $ 83 $ - $ 83 $ 84 $ - $ 84 2017 Subordinated Note Financing 1,028 363 1,391 1,048 325 1,373 Opus Credit Facility 281 113 394 281 319 600 2018 Venture Notes 429 146 575 56 17 73 LOC Fees 15 – 15 7 – 7 Helocyte Convertible Note – – – 68 – 68 Caelum Convertible Note – – – 196 – 196 Mustang Horizon Notes 11 – 11 – – – Other – – – 2 – 2 Total Interest Expense and Financing Fee $ 1,847 $ 622 $ 2,469 $ 1,742 $ 661 $ 2,403 Note 1: amortization of fees

Leases

Leases	3 Months Ended
Leases	Mar. 31, 2019
Leases [Abstract]
Leases	11. Leases On October 3, 2014, the Company entered into a 15-year lease for office space at 2 Gansevoort Street, New York, NY 10014, at an average annual rent of $2.7 million. The Company took possession of this space, which serves as its principal executive offices, in December 2015, and took occupancy in April 2016. Total rent expense, over the full term of the lease for this space will approximate $40.7 million. In conjunction with the lease, entered into Desk Space Agreements with two related parties: OPPM and TGTX, to occupy 10% and 45%, respectively, of the office space that requires them to pay their share of the average annual rent of $0.3 million and $1.1 million, respectively. The total net rent expense will approximate $16.0 million over the lease term. These initial rent allocations will be adjusted periodically for each party based upon actual percentage of the office space occupied. Additionally, reserved the right to execute desk space agreements with other third parties and those arrangements will also affect the cost of the lease actually borne by us. In October 2015, the Company entered into a 5-year lease for approximately 6,100 square feet of office space in Waltham, MA at an average annual rent of approximately $0.2 million. The Company took occupancy of this space in January 2016. Journey In June 2017, Journey extended its lease for 2,295 square feet of office space in Scottsdale, AZ by one year, at an average annual rent of approximately $55,000. Journey originally took occupancy of this space in November 2014. In August 2018, Journey amended their lease and entered into a new two-year extension for 3,681 square feet of office space in the same location in Scottsdale, AZ at an annual rate of approximately $94,000. The term of this amended lease commenced on December 1, 2018 and will expire on November 30, 2020. Mustang On October 27, 2017, Mustang entered into a lease agreement with WCS - 377 Plantation Street, Inc., a Massachusetts nonprofit corporation (“Landlord”). Pursuant to the terms of the lease agreement, Mustang agreed to lease 27,043 square feet from the Landlord, located at 377 Plantation Street in Worcester, MA (the “Facility”), through November 2026, subject to additional extensions at Mustang’s option. Base rent, net of abatements of $0.6 million over the lease term, totals approximately $3.6 million, on a triple-net basis. Mustang improvements to the facility of approximately $3.9 million. The Facility initiated cell processing operations for both personalized CAR T and gene therapies in late 2018. The Company leases copiers under agreements classified as operating leases that expire on various dates through 2021. Most of the Company’s lease liabilities result from the lease of its New York City, NY office, which expires in 2031 and Mustang’s Worcester, MA cell processing facility lease which expires in 2026. Such leases do not require any contingent rental payments, impose any financial restrictions, or contain any residual value guarantees. Certain of the Company’s leases include renewal options and escalation clauses; renewal options have not been included in the calculation of the lease liabilities and right of use assets as the Company is not reasonably certain to exercise the options. The Company does not act as a lessor or have any leases classified as financing leases. At March 31, 2019, the Company had operating lease liabilities of $26.5 million and right of use assets of $22.6 million, which were included in the condensed balance sheet. During the three months ended March 31, 2019, the Company recorded $0.8 million as lease expense to current period operations. As of ($ in thousands) March 31, 2019 Lease cost Operating lease cost $ 796 Shared lease costs (477 ) Variable lease cost 26 Total lease cost $ 345 The following tables summarize quantitative information about the Company’s operating leases, under the adoption of Topic 842 ($ in thousands) Three Months Ended March 31, 2019 Operating cash flows from operating leases $ (767 ) Right-of-use assets exchanged for new operating lease liabilities $ 22,618 Weighted-average remaining lease term – operating leases (years) 6.7 Weighted-average discount rate – operating leases 6.2 % ($ in thousands) Future Lease Nine months ended December 31, 2019 $ 1,871 Year ended December 31, 2020 3,351 Year ended December 31, 2021 3,114 Year ended December 31, 2022 3,084 Year ended December 31, 2023 3,137 Other 23,463 Total operating lease liabilities 38,020 Less: present value discount (11,550 ) Net operating lease liabilities, short-term and long-term $ 26,470 At December 31, 2018, the total future minimum lease payments under all leases were: ($ in thousands) 2019 $ 3,070 2020 3,289 2021 3,084 2022 3,084 2023 3,137 Beyond 23,466 Total minimum lease payments $ 39,130

Accrued Liabilities and other L

Accrued Liabilities and other Long-Term Liabilities	3 Months Ended
Accrued Liabilities and other Long-Term Liabilities	Mar. 31, 2019
Payables and Accruals [Abstract]
Accrued Liabilities and other Long-Term Liabilities	12. Accrued Liabilities and other Long-Term Liabilities Accrued expenses and other long-term liabilities consisted of the following: ($ in thousands) March 31, 2019 December 31, 2018 Accrued expenses: Professional fees $ 1,262 $ 1,434 Salaries, bonuses and related benefits 5,592 5,843 Accrued expenses - related party 16 – Research and development 4,855 3,805 Research and development - milestones – 200 Research and development - manufacturing 826 826 Research and development - clinical supplies 215 160 Research and development - license maintenance fees 489 519 Dr. Falk Pharma settlement 300 300 Accrued royalties payable 1,233 1,108 Accrued coupon expense 993 838 Other 4,546 1,327 Total accrued expenses $ 20,327 $ 16,360 Other long-term liabilities: Deferred expenses related to build-out 1 2,276 5,211 Total other long-term liabilities $ 2,276 $ 5,211 Note 1: As of March 31, 2019, balance consists of deferred charges related to build-out of the New York facility, and as of December 31, 2018, balance consists of deferred rent and deferred build out charges.

Non-Controlling Interests

Non-Controlling Interests	3 Months Ended
Non-Controlling Interests	Mar. 31, 2019
Noncontrolling Interest [Abstract]
Non-Controlling Interests	13. Non-Controlling Interests Non-controlling interests in consolidated entities are as follows: For the three months ended As of March 31, 2019 March 31, 2019 As of March 31, 2019 ($ in thousands) NCI equity share Net loss attributable to non- controlling interests Non-controlling interests in consolidated entities Non-controlling ownership Aevitas $ (1,125 ) $ (138 ) $ (1,263 ) 36.1 % Avenue 2 23,702 (8,000 ) (15,702 ) 77.2 % Caelum 3 – – – 60.1 % Cellvation (670 ) (53 ) (723 ) 21.1 % Checkpoint 1 8,754 (3,932 ) 4,822 68.1 % Coronado SO (290 ) – (290 ) 13.0 % Cyprium (279 ) (43 ) (322 ) 10.6 % Helocyte (4,045 ) (48 ) (4,093 ) 19.3 % JMC (227 ) 24 (203 ) 6.9 % Mustang 2 22,211 (5,419 ) 16,792 58.9 % Tamid (492 ) (38 ) (530 ) 23.4 % Total $ 47,539 $ (17,647 ) $ 29,892 For the twelve months ended As of December 31, 2018 December 31, 2018 As of December 31, 2018 ($ in thousands) NCI equity share Net loss attributable to non- controlling interests Non-controlling interests in consolidated entities Non-controlling ownership Aevitas $ (474 ) $ (606 ) $ (1,080 ) 36.1 % Avenue 2 13,326 (13,735 ) (409 ) 64.81 % Caelum (2,436 ) (2,413 ) (4,849 ) 36.8 % Cellvation (457 ) (185 ) (642 ) 21.1 % Checkpoint 1 31,648 (23,470 ) 8,178 69.3 % Coronado SO (290 ) – (290 ) 13.0 % Cyprium (210 ) (62 ) (272 ) 10.8 % Helocyte (3,372 ) (684 ) (4,056 ) 19.8 % JMC (475 ) 245 (230 ) 6.9 % Mustang 2 38,631 (16,628 ) 22,003 60.5 % Tamid (211 ) (251 ) (462 ) 23.4 % Total $ 75,680 $ (57,789 ) $ 17,891 Note 1: Checkpoint is consolidated with Fortress’ operations because Fortress maintains voting control through its ownership of Checkpoint’s Class A Common Shares which provide super-majority voting rights. Note 2: Avenue and Mustang are consolidated with Fortress’ operations because Fortress maintains voting control through its ownership of Preferred Class A Shares which provide super-majority voting rights. Note 3: Effective January 30, 2019, Caelum ceased to be a controlled Fortress entity and as such is no longer consolidated.

Net Income (Loss) per Common Sh

Net Income (Loss) per Common Share	3 Months Ended
Net Income (Loss) per Common Share	Mar. 31, 2019
Earnings Per Share [Abstract]
Net Income (Loss) per Common Share	14. Net Income (Loss) per Common Share The following table sets forth the computation of earnings per share (amounts in thousands except share and per share data): Three Months Ended March 31, 2019 2018 Net income (loss) attributable to common stockholders $ 1,392 $ (21,018 ) Weighted average shares outstanding - basic 48,506,994 42,518,403 Preferred stock, Series A 1,000,000 – Stock options 378,835 – Warrants 60,000 – Unvested restricted stock 12,622,076 – Unvested restricted stock units 1,243,231 – Weighted average shares outstanding - diluted 63,811,136 42,518,403 Per share data: Basic $ 0.03 $ (0.49 ) Diluted $ 0.02 $ (0.49 ) Basic income (loss) per share is calculated by dividing income (loss) by the weighted-average number of shares of common stock outstanding for the period, without consideration for common stock equivalents. Diluted income (loss) per share is computed by dividing income (loss) by the weighted-average number of common stock and common stock equivalents outstanding for the period. The Company’s common stock equivalents, including unvested restricted stock, options, and warrants have been excluded from the computation of diluted income (loss) per share for the three months ended March 31, 2018 as the effect would be to reduce the income (loss) per share. Therefore, the weighted average common stock outstanding used to calculate both basic and diluted income (loss) per share is the same for the quarter ended March 31, 2018. The following shares of potentially dilutive securities have been excluded from the computations of diluted weighted average shares outstanding, as the effect of including such securities would be anti-dilutive at the end of the three months ended March 31, 2018: March 31, 2018 Warrants to purchase Common Stock 894,189 Opus warrants to purchase Common Stock 1,880,000 Options to purchase Common Stock 1,085,501 Convertible Preferred Stock 1,000,000 Unvested Restricted Stock 11,050,943 Unvested Restricted Stock Units 1,778,154 Total 17,688,787

Stockholders' Equity

Stockholders' Equity	3 Months Ended
Stockholders' Equity	Mar. 31, 2019
Stockholders' Equity Note [Abstract]
Stockholders' Equity	15. Stockholders’ Equity Stock-based Compensation The following table summarizes the stock-based compensation expense from stock option, employee stock purchase programs and restricted Common Stock awards and warrants for the three months ended March 31, 2019 and 2018: For the Three Months Ended March 31, ($ in thousands) 2019 2018 Employee awards $ 935 $ 942 Executive awards of Fortress partner companies’ stock 352 518 Non-employee awards (2 ) 23 Fortress partner companies: Avenue 751 349 Checkpoint 798 1,137 Mustang 432 1,995 Other 43 (169 ) Total stock-based compensation $ 3,309 $ 4,795 For the three months ended March 31, 2019 and 2018, approximately $0.6 million and $2.3 million, respectively, of stock-based compensation expense was included in research and development expenses in connection with equity grants made to employees and consultants and approximately $2.7 million and $2.5 million, respectively, was included in general and administrative expenses in connection with grants made to employees, members of the board of directors and consultants. Stock Options The following table summarizes Fortress stock option activities excluding activity related to Fortress partner companies: Number of shares Weighted average exercise price Total weighted average intrinsic value Weighted average remaining contractual life (years) Options vested and expected to vest at December 31, 2018 1,085,501 $ 3.75 $ – 2.93 Exercised – – – – Options vested and expected to vest at March 31, 2019 1,085,501 $ 3.75 $ 155,322 2.68 Options vested and exercisable 1,085,501 $ 3.75 $ 155,322 2.68 As of March 31, 2019, Fortress had no unrecognized stock-based compensation expense related to options. Restricted Stock and Restricted Stock Units The following table summarizes Fortress restricted stock awards and restricted stock units activities, excluding activities related to Fortress Companies: Number of shares Weighted average grant price Unvested balance at December 31, 2018 12,645,982 $ 2.72 Restricted stock granted 1,516,408 0.86 Restricted stock vested (220,000 ) 2.82 Restricted stock units forfeited (43,333 ) 4.56 Restricted stock units vested (33,750 ) 3.59 Unvested balance at March 31, 2019 13,865,307 $ 2.51 As of March 31, 2019 and 2018 , the Company had unrecognized stock-based compensation expense related to restricted stock and restricted stock unit awards of approximately $ 14.8 million and $2.5 million, respectively, which is expected to be recognized over the remaining weighted-average vesting period of 5.4 years and 2.4 years, respectively. Warrants The following table summarizes Fortress warrant activities, excluding activities related to Fortress Companies: Number of shares Weighted average exercise price Total weighted average intrinsic value Weighted average remaining contractual life (years) Outstanding as of December 31, 2018 2,754,189 $ 3.28 $ – 3.49 Granted – – – – Forfeited – – – – Outstanding as of March 31, 2019 2,754,189 $ 3.28 $ 24,600 3.25 Exercisable as of March 31, 2019 849,189 $ 3.92 $ 24,600 2.89 Employee Stock Purchase Plan Eligible employees can purchase the Company’s Common Stock at the end of a predetermined offering period at 85% of the lower of the fair market value at the beginning or end of the offering period. The ESPP is compensatory and results in stock-based compensation expense. As of March 31, 2019, 356,507 shares have been purchased and 643,493 shares are available for future sale under the Company’s ESPP. Share-based compensation expense recorded was approximately $20,000 and $38,000, respectively, for the three months ended March 31, 2019 and 2018. Capital Raises At-the-Market Offering Pursuant to the terms of the Company’s Amended and Restated At Market Issuance Sales Agreement, or Sales Agreement, with B. Riley FBR, Inc. (“B. Riley,” f/k/a MLV & Co. LLC, and FBR Capital Markets & Co.) (the “ATM”), for the three-month period ended March 31, 2019, the Company issued approximately 2.9 million shares of common stock at an average price of $2.14 per share for gross proceeds of $6.3 million. In connection with these sales, the Company paid aggregate fees of approximately $0.1 million. These shares were sold pursuant to the current shelf registration statement on Form S-3; approximately $10.2 million of the shelf remains available for sale at March 31, 2019. Checkpoint Therapeutics, Inc. Checkpoint At-the-Market Offering In November 2017, Checkpoint filed a shelf registration statement on Form S-3 (the "Checkpoint S-3"), which was declared effective in December 2017. Under the Checkpoint S-3, Checkpoint may sell up to a total of $100 million of its securities. In connection with the Checkpoint S-3, Checkpoint entered into an At-the-Market Issuance Sales Agreement (the "Checkpoint ATM") with Cantor Fitzgerald & Co., Ladenburg Thalmann & Co. Inc. and H.C. Wainwright & Co., LLC (each an "Agent" and collectively, the "Agents"), relating to the sale of shares of common stock. Under the Checkpoint ATM, Checkpoint pays the Agents a commission rate of up to 3.0% of the gross proceeds from the sale of any shares of common stock. During the three months ended March 31, 2019, Checkpoint sold a total of 90,269 shares of its common stock under the Checkpoint ATM for aggregate total gross proceeds of approximately $0.4 million at an average selling price of $4.05 per share. Pursuant to the Founders Agreement, Checkpoint issued 2,254 shares of common stock to Fortress for the ATM offering noted above. Approximately $68.6 million of the shelf remains available for sale under the Checkpoint S-3, following the offerings noted above. Checkpoint may offer the securities under the Checkpoint S-3 from time to time in response to market conditions or other circumstances if it believes such a plan of financing is in the best interests of its stockholders.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	16. Commitments and Contingencies Indemnification In accordance with its certificate of incorporation, bylaws and indemnification agreements, the Company has indemnification obligations to its officers and directors for certain events or occurrences, subject to certain limits, while they are serving at the Company’s request in such capacity. There have been no claims to date, and the Company has director and officer insurance to address such claims. Pursuant to agreements with clinical trial sites, the Company provides indemnification to such sites in certain conditions. Legal Proceedings In the ordinary course of business, the Company and its subsidiaries may be subject to both insured and uninsured litigation. Suits and claims may be brought against the Company by customers, suppliers, partners and/or third parties (including tort claims for personal injury arising from clinical trials of the Company’s product candidates and property damage) alleging deficiencies in performance, breach of contract, etc., and seeking resulting alleged damages.

Related Party Transactions

Related Party Transactions	3 Months Ended
Related Party Transactions	Mar. 31, 2019
Related Party Transactions [Abstract]
Related Party Transactions	17. Related Party Transactions Other Related Parties The Company’s Chairman, President and Chief Executive Officer, individually and through certain trusts over which he has voting and dispositive control, beneficially owned approximately 15.3% of the Company’s issued and outstanding Common Stock as of March 31, 2019. The Company’s Executive Vice Chairman, Strategic Development owns approximately 14.9% of the Company’s issued and outstanding Common Stock at March 31, 2019. Shared Services Agreement with TGTX TGTX and the Company entered into an arrangement to share the cost of certain research and development employees. The Company’s Executive Vice Chairman, Strategic Development, is Executive Chairman and Interim Chief Executive Officer of TGTX. Under the terms of the Agreement, TGTX will reimburse the Company for the salary and benefit costs associated with these employees based upon actual hours worked on TGTX related projects. For the three months ended March 31, 2019 and 2018, the Company invoiced TGTX $0.1 million and $0.3 million, respectively. At March 31, 2019, the amount receivable from TGTX related to this arrangement approximated $0.1 million. Desk Space Agreements with TGTX and OPPM In connection with the Company’s Desk Space Agreements with TGTX and Opus Point Partners Management, LLC (“OPPM”), as of March 31, 2019, the Company had paid $0.7 million in rent under the Desk Space Agreements, and invoiced TGTX and OPPM approximately $0.3 million and $0.1 million, respectively, for their prorated share of the rent base. At March 31, 2019, the amount due from TGTX approximated $0.4 million and the amount due from OPPM approximated $0.4 million. Opus Credit Facility On March 12, 2018, the Company and OPHIF amended and restated the Opus Credit Facility (the “A&R Opus Credit Facility”). The A&R Opus Credit Facility extends the maturity date of the notes issued under the Opus Credit Facility from September 14, 2018 by one year to September 14, 2019. The A&R Opus Credit Facility also permits the Company to make portions of interest and principal repayments in the form of shares of the Company’s common stock and/or in common stock of the Company’s publicly-traded subsidiaries, subject to certain conditions. Fortress retains the ability to prepay the Notes at any time without penalty. The notes payable under the A&R Opus Credit Facility continue to bear interest at 12% per annum. For the three months ended March 31, 2019 and 2018, the Company paid nil and $0.3 million, respectively. Founders Agreements The Company has entered into Founders Agreements and, in some cases, Exchange Agreements with certain of its subsidiaries as described in the Company’s Form 10-K for the year ended December 31, 2018, filed with the SEC on March 18, 2019. The following table summarizes, by subsidiary, the effective date of the Founders Agreements and PIK dividend or equity fee payable to the Company in accordance with the terms of the Founders Agreements, Exchange Agreements and the subsidiaries’ certificates of incorporation. Fortress Partner Company Effective Date (1) PIK Dividend as a % of fully diluted outstanding capitalization Class of Stock Issued Helocyte March 20, 2015 2.5 % Common Stock Avenue February 17, 2015 0.0 % (2) Common Stock Mustang March 13, 2015 2.5 % Common Stock Checkpoint March 17, 2015 0.0 % (3) Common Stock Cellvation October 31, 2016 2.5 % Common Stock Caelum January 1, 2017 0.0 % (4) Common Stock Cyprium March 13, 2017 2.5 % Common Stock Aevitas July 28, 2017 2.5 % Common Stock Tamid November 30, 2017 (5) 2.5 % Common Stock Note 1: Represents the effective date of each subsidiary’s Founders Agreement. Each PIK dividend and equity fee is payable on the annual anniversary of the effective date of the original Founders Agreement or has since been amended to January 1 of each calendar year. Note 2: Concurrently with the execution and delivery of the Stock Purchase and Merger Agreement (“SPMA”) entered into between, Avenue, the Company and InvaGen Pharmaceuticals Inc. (“InvaGen”) (together, the “SPMA Parties”), the SPMA Parties entered into a waiver agreement (the “Waiver Agreement”), pursuant to which the Company irrevocably waived its right to receive the annual dividend of Avenue’s common shares under the terms of the Class A preferred stock and any fees, payments, reimbursements or other distributions under the management services agreement between the Company and Avenue and the Founders Agreement, for the period from the effective date of the Waiver Agreement to the termination of InvaGen’s rights under the SPMA. Pursuant to the Waiver Agreement, immediately prior to the closing of the Merger Transaction contemplated under the SPMA, the Company will convert all of its preferred shares into common shares pursuant to the terms of the certificate of incorporation of Avenue, as amended from time to time. Note 3: Instead of a PIK dividend, Checkpoint pays the Company an annual equity fee in shares of Checkpoint’s common stock equal to 2.5% of Checkpoint’s fully diluted outstanding capitalization. Note 4: Effective January 31, 2019 the Caelum Founders Agreement and MSA with Fortress were terminated in conjunction with the execution of a Development Option and Share Purchase Agreement (“DOSPA”) between Caelum and Alexion Therapeutics, Inc. (See Note 4). Note 5: Represents the Trigger Date, the date that the Fortress partner company first acquires, whether by license or otherwise, ownership rights in a product. Management Services Agreements The Company has entered in Management Services Agreements (the “MSAs”) with certain of its subsidiaries as described in the Company’s Form 10-K for the year ended December 31, 2018, filed with the SEC on March 18, 2019. The following table summarizes, by subsidiary, the effective date of the MSA and the annual consulting fee payable by the subsidiary to the Company in quarterly installments: Fortress partner company Effective Date Annual MSA Fee (Income)/Expense Helocyte March 20, 2015 $ 500 Avenue (1) February 17, 2015 – Mustang March 13, 2015 500 Checkpoint March 17, 2015 500 Cellvation October 31, 2016 500 Caelum (2) January 1, 2017 – Cyprium March 13, 2017 500 Aevitas July 28, 2017 500 Tamid November 30, 2017 500 Fortress (3,500 ) Consolidated (Income)/Expense $ – Note 1: Concurrently with the execution and delivery of the SPMA entered into between, Avenue, the Company and InvaGen Pharmaceuticals Inc. (“InvaGen”) (together, the “SPMA Parties”), the SPMA Parties entered into a waiver agreement (the “Waiver Agreement”), pursuant to which the Company irrevocably waived its right to receive the annual dividend of Avenue’s common shares under the terms of the Class A preferred stock and any fees, payments, reimbursements or other distributions under the management services agreement between the Company and Avenue and the Founders Agreement, for the period from the effective date of the Waiver Agreement to the termination of InvaGen’s rights under the SPMA. Pursuant to the Waiver Agreement, immediately prior to the closing of the Merger Transaction contemplated under the SPMA, the Company will convert all of its preferred shares into common shares pursuant to the terms of the certificate of incorporation of Avenue, as amended from time to time. (See Note 4). Note 2: Effective January 31, 2019 the Caelum Founders Agreement and MSA with Fortress were terminated in conjunction with the execution of a DOSPA between Caelum and Alexion Therapeutics, Inc. and $1.0 million of fees accrued under the MSA were written off (See Note 4).

Segment Information

Segment Information	3 Months Ended
Segment Information	Mar. 31, 2019
Segment Reporting [Abstract]
Segment Information	18. Segment Information The Company operates in two reportable segments, Dermatology Product Sales and Pharmaceutical and Biotechnology Product Development. The accounting policies of the Company’s segments are the same as those described in Note 2. Prior to the sale of National the Company operated in three segments, one of which included National, see Note 3. The following tables summarize, for the periods indicated, operating results, from continued operations by reportable segment: Dermatology Pharmaceutical and Biotechnology ($ in thousands) Products Product Three Months Ended March 31, 2019 Sales Development Consolidated Net Revenue $ 6,125 $ 352 $ 6,477 Direct cost of goods (1,884 ) – (1,884 ) Sales and marketing costs (3,493 ) – (3,493 ) Research and development – (23,723 ) (23,723 ) General and administrative (387 ) (9,598 ) (9,985 ) Segment income (loss) from operations $ 361 $ (32,969 ) $ (32,608 ) Segment assets $ 11,079 $ 189,459 $ 200,538 ($ in thousands) Three Months Ended March 31, 2018 Dermatology Products Sales Pharmaceutical and Biotechnology Product Development Consolidated Net Revenue $ 5,509 $ 394 $ 5,903 Direct cost of goods (1,472 ) – (1,472 ) Sales and marketing costs (2,764 ) – (2,764 ) Research and development – (25,055 ) (25,055 ) General and administrative (397 ) (10,387 ) (10,784 ) Segment income (loss) from operations $ 876 $ (35,048 ) $ (34,172 ) Segment assets $ 11,163 $ 189,560 $ 200,723 Assets held for sale 64,352 Total consolidated $ 265,075

Revenues from Contracts and Sig

Revenues from Contracts and Significant Customers	3 Months Ended
Revenues from Contracts and Significant Customers	Mar. 31, 2019
Revenues [Abstract]
Revenues From Contracts And Significant Customers	19. Revenues from Contracts and Significant Customers Disaggregation of Total Revenues The Company has three marketed products, Targadox®, Luxamend®, Ceracade® and Exelderm®. Substantially all of the Company’s product revenues are recorded in the U.S. Substantially all of the Company’s collaboration revenues are from its collaboration with TGTX. Revenues by product and collaborator are summarized as follows (in thousands): Three months ended March 31, 2019 2018 Targadox® $ 5,700 $ 5,498 Other branded revenue 425 11 Total product revenues $ 6,125 $ 5,509 TGTX 352 394 Total Revenue $ 6,477 $ 5,903 Significant Customers For the three months ended March 31, 2019, one of the Company’s Dermatology Products customers accounted for more than 10.0 19.9 For the three months ended March 31, 2018, three of the Company’s Dermatology Products customers each accounted for more than 10.0% of its total gross product revenue in the amount of $ 4.4 3.9 2.0 At March 31, 2019, one of the Company’s Dermatology Products customers accounted for more than 10.0% of its total accounts receivable balance in the amount of $7.7 million. At March 31, 2018, two of the Company’s Dermatology Products customers each accounted for more than 10.0% of its total accounts receivable balance in the amount of $3.0 million and $2.1 million, respectively.

Incomes taxes

Incomes taxes	3 Months Ended
Incomes taxes	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Incomes taxes	20. Incomes taxes The Company and its subsidiaries are subject to US federal and state income taxes. Income tax expense is the total of the current year income tax due or refundable and the change in deferred tax assets and liabilities. Deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases and operating loss and tax credit carry-forwards. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. Deferred tax assets are reduced by a valuation allowance when, in the opinion of Management, it is more likely than not that some portion, or all, of the deferred tax asset will not be realized. The Company files a consolidated income tax return with subsidiaries for which the Company has an 80% or greater ownership interest. Subsidiaries for which the Company does not have an 80% or more ownership are not included in the Company’s consolidated income tax group and file their own separate income tax return. As a result, certain corporate entities included in these financial statements are not able to combine or offset their taxable income or losses with other entities’ tax attributes. Income tax expense for the three months ended March 31, 2019 and 2018 is based on the estimated annual effective tax rate.

Subsequent Events

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	21. Subsequent Events Capital Raises Mustang At-the-Market Offering Pursuant to the terms of the Company’s Amended and Restated At Market Issuance Sales Agreement, or Sales Agreement, with B. Riley FBR, Inc. (“B. Riley,” f/k/a MLV & Co. LLC, and FBR Capital Markets & Co.) (the “ATM”), subsequent to the quarter ended March 31, 2019, the Company issued approximately 3.5 million shares of common stock at an average price of $6.42 per share for gross proceeds of $22.5 million. In connection with these sales, the Company paid aggregate fees of approximately $0.4 million. These shares were sold pursuant to Mustang’s current shelf registration statement on Form S-3; approximately $20.9 million of the shelf remains available for sale as of the date of filing. Mustang Public Offering of Common Stock On April 30, 2019, Mustang announced the pricing of an underwritten public offering, whereby it sold 6,875,000 shares of its common stock, (plus a 30-day option to purchase up to an additional 1,031,250 shares of common stock, which has been exercised) at a price of $4.00 per share for gross proceeds of approximately $31.6 million, before deducting underwriting discounts and commissions and offering expenses. The shares were sold under a Registration Statement (No. 333-226175) on Form S-3, filed by Mustang with the Securities and Exchange Commission. The offering closed on May 2, 2019, with the over-allotment closing on May 8, 2019.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2019
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (“GAAP”) for interim financial information and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, the unaudited interim condensed consolidated financial statements reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the balances and results for the periods presented. Certain information and footnote disclosures normally included in the Company’s annual financial statements prepared in accordance with GAAP have been condensed or omitted. These condensed consolidated financial statement results are not necessarily indicative of results to be expected for the full fiscal year or any future period. The unaudited condensed consolidated financial statements and related disclosures have been prepared with the presumption that users of the unaudited condensed consolidated financial statements have read or have access to the audited financial statements for the preceding fiscal year for each of the companies: Avenue, Checkpoint and Mustang. Accordingly, these unaudited condensed consolidated financial statements should be read in conjunction with the Company’s Form 10-K, which was filed with the United States Securities and Exchange Commission (“SEC”) on March 18, 2019, from which the Company derived the balance sheet data at December 31, 2018, as well as Checkpoint’s Form 10-K filed with the SEC on March 18, 2019, Mustang’s Form 10-K, filed with the SEC on March 18, 2019, and Avenue’s Form 10-K, filed with the SEC on March 12, 2019. The Company’s unaudited condensed consolidated financial statements include the accounts of the Company and its subsidiaries: Avenue, Aevitas, CB Securities Corporation, Cellvation, Coronado SO Co., Checkpoint, Cyprium, Escala Therapeutics, Inc., GeneXion Oncology, Inc., Helocyte, Immune Limited, JMC, Mustang, Tamid, Fortress Biotech China, Inc., FBIO Acquisition Corp. IV, FBIO Acquisition Corps. VI - XIV, and JG Pharma, Inc., a subsidiary of JMC. All intercompany balances and transactions have been eliminated. The preparation of the Company’s unaudited condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the unaudited condensed consolidated financial statements and the reported amounts of expenses during the reporting period.
Use of Estimates	Use of Estimates The Company’s unaudited condensed consolidated financial statements include certain amounts that are based on management’s best estimates and judgments. The Company’s significant estimates include, but are not limited to, useful lives assigned to long-lived and intangible assets, fair value measurements, stock-based compensation, common stock issued to acquire licenses, investments, accrued expenses, derivative warrant liabilities, revenue with customers, provisions for income taxes and contingencies. Due to the uncertainty inherent in such estimates, actual results may differ from these estimates.
Discontinued Operations	Discontinued Operations At December 31, 2018, the Company determined that its National segment met the discontinued operations criteria set forth in Accounting Standards Codification (ASC) Subtopic 205-20-45, Presentation of Financial Statements Consolidated Statements of Operations. See Note 3 for more information relating to the Company’s discontinued operations.
Significant Accounting Policies	Significant Accounting Policies There have been no material changes in the Company’s significant accounting policies to those previously disclosed in the 2018 Annual Report other than the adoption of the Financial Accounting Standards Board (FASB) Accounting Standard Updates (ASU) ASU 2016-02, Leases, and 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting .
Leases	Leases Effective January 1, 2019, the Company accounts for its leases under ASC 842, Leases . Under this guidance, arrangements meeting the definition of a lease are classified as operating or financing leases, and are recorded on the condensed consolidated balance sheet as both a right-of-use asset and lease liability, calculated by discounting fixed lease payments over the lease term at the rate implicit in the lease or the Company’s incremental borrowing rate. Lease liabilities are increased by interest and reduced by payments each period, and the right-of-use asset is amortized over the lease term. For operating leases, interest on the lease liability and the amortization of the right-of-use asset result in straight-line rent expense over the lease term. For finance leases, interest on the lease liability and the amortization of the right-of-use asset results in front-loaded expense over the lease term. Variable lease expenses are recorded when incurred. In calculating the right-of-use asset and lease liability, the Company elects to combine lease and non-lease components. The Company continues to account for leases in the prior period financial statements under ASC Topic
Stock-Based Compensation	Stock-Based Compensation The Company expenses stock-based compensation to employees over the requisite service period based on the estimated grant-date fair value of the awards and forfeiture rates. For stock-based compensation awards to non-employees, prior to the adoption of ASU 2018-07 on January 1, 2019, the Company remeasured the fair value of the non-employee awards at each reporting period prior to vesting and finally at the vesting date of the award. Changes in the estimated fair value of these non-employee awards were recognized as compensation expense in the period of change. Subsequent to the adoption of ASU 2018-07, the Company recognizes non-employees compensation costs over the requisite service period based on a measurement of fair value for each stock award. The Company estimates the fair value of stock option grants using the Black-Scholes option pricing model or 409A valuations, as applicable. The assumptions used in calculating the fair value of stock-based awards represent management’s best estimates and involve inherent uncertainties and the application of management’s judgment.
Recently Issued Accounting Standards	Recently Adopted Accounting Pronouncements In August 2018, the SEC adopted the final rule under SEC Release No. 33-10532, Disclosure Update and Simplification , amending certain disclosure requirements that were redundant, duplicative, overlapping, outdated or superseded. In addition, the amendments expanded the disclosure requirements on the analysis of stockholders' equity for interim financial statements. Under the amendments, an analysis of changes in each caption of stockholders' equity presented in the balance sheet must be provided in a note or separate statement. The analysis should present a reconciliation of the beginning balance to the ending balance of each period for which a statement of comprehensive income is required to be filed. This final rule became effective on November 5, 2018. The Company included the required presentation of changes in stockholders’ equity in this Form 10-Q. In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting financial statements. In July 2017, the FASB issued ASU 2017-11, Earnings Per Share (Topic 260), Distinguishing Liabilities from Equity (Topic 480) and Derivatives and Hedging (Topic 815): I. Accounting for Certain Financial Instruments with Down Round Features; II. Replacement of the Indefinite Deferral for Mandatorily Redeemable Financial Instruments of Certain Nonpublic Entities and Certain Mandatorily Redeemable Noncontrolling Interests with a Scope Exception financial statements. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) in order to increase transparency and comparability among organizations by, among other provisions, recognizing lease assets and lease liabilities on the balance sheet for those leases classified as operating leases under previous GAAP. For public companies, ASU 2016-02 is effective for fiscal years beginning after December 15, 2018 (including interim periods within those periods) using a modified retrospective approach and early adoption is permitted. In transition, entities may also elect a package of practical expedients that must be applied in its entirety to all leases commencing before the adoption date, unless the lease is modified, and permits entities to not reassess (a) the existence of a lease, (b) lease classification or (c) determination of initial direct costs, as of the adoption date, which effectively allows entities to carryforward accounting conclusions under previous U.S. GAAP. In July 2018, the FASB issued ASU 2018-11, Leases (Topic 842): Targeted Improvements Recent Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments - Credit Losses (Topic 326) : Measurement of Credit Losses on Financial Instruments. ASU 2016-13 requires that expected credit losses relating to financial assets are measured on an amortized cost basis and available-for-sale debt securities be recorded through an allowance for credit losses. ASU 2016-13 limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and also requires the reversal of previously recognized credit losses if fair value increases. The new standard will be effective on January 1, 2020 and may be adopted earlier. The Company is currently evaluating the impact, if any, that ASU 2016-13 will have on its condensed consolidated financial statements and related disclosures. In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820), - Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement , which makes a number of changes meant to add, modify or remove certain disclosure requirements associated with the movement amongst or hierarchy associated with Level 1, Level 2 and Level 3 fair value measurements. This guidance is effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2019. Early adoption is permitted upon issuance of the update. The Company does not expect the adoption of this guidance to have a material impact on its financial statements.

Discontinued Operations (Tables

Discontinued Operations (Tables)	3 Months Ended
Discontinued Operations (Tables)	Mar. 31, 2019
Discontinued Operations and Disposal Groups [Abstract]
Statement of Operations of Disposal Group Including Discontinued Operation	The following is a summary of revenue and expenses of National for the three months ended March 31, 2019 and 2018: Three months ended March 31, ($ in thousands) 2019 2018 Revenue $ – $ 49,522 Operating expenses Commissions, compensation and fees – 43,561 Clearing fees – 743 Communications – 760 Occupancy – 955 Licenses and registration – 637 Professional fees – 1,393 Underwriting costs – 145 Interest – 2 Depreciation and amortization – 859 Other administrative expenses – 1,781 Total operating expenses – 50,836 Gain (loss) from operations – (1,314 ) Other income (expenses) Change in fair value of derivative liabilities – (1,088 ) Interest expense and financing fees – 320 Interest income – 6 Total other expenses – (762 ) Total loss from discontinued operations $ – $ (2,076 )
Balance Sheet Of Disposal Group Including Discontinued Operations	In connection with this sale, the Company classified the assets and liabilities related to National, included on its condensed consolidated balance sheet as of March 31, 2019 and December 31, 2018, as held for sale as presented in the table below: March 31, December 31, ($ in thousands) 2019 2018 ASSETS Current assets Current assets held for sale $ – $ 13,089 Total current assets held for sale – 13,089 Total assets held for sale $ – $ 13,089
Cash Flow Statement of Disposal Group Including Discontinued Operation	The table below depicts the cash flows from the transaction for the three months ended March 31, 2019 and 2018, respectively: Three months ended March 31, ($ in thousands) 2019 2018 Operating activities Effect of elimination entry on discontinued operations presentation $ – $ (305 ) Net loss on discontinued operations – (2,076 ) Total cash used in discontinued operating activities $ – $ (2,381 ) Investing activities Proceeds from sale of National $ 13,089 $ – Total cash provided by discontinued investing activities $ 13,089 $ –

Collaboration and Stock Purch_2

Collaboration and Stock Purchase Agreements (Tables)	3 Months Ended
Collaboration and Stock Purchase Agreements (Tables)	Mar. 31, 2019
Collaboration And Stock Purchase Agreements [Abstract]
Summary of Assets and Liabilities Of Caelum Impacted By Deconsolidation	The following table provides a summary of the assets and liabilities of Caelum impacted by the deconsolidation: January ($ in thousands) 2019 ASSETS Current assets Cash and cash equivalents $ 1,201 Prepaid expenses and other current assets 6 Total current assets held for sale $ 1,207 LIABILITIES Current liabilities Accounts payable and accrued expenses $ 2,246 Interest payable 198 Interest payable - related party 106 Note payable - related party 929 Note payable 9,914 Warrant liability 991 Other current liabilities 14,384 Net liabilities impacted by deconsolidation $ 13,177
Condensed Consolidated Financial Statements	In connection with this transaction the Company recorded a gain resulting from the deconsolidation of Caelum on its condensed consolidated financial statements for the three months ended March 31, 2019: ($ in thousands) Gain on deconsolidation of Caelum Fair value of Caelum $ 11,056 Net liabilities deconsolidated 13,177 Non-controlling interest share (4,849 ) Write off of MSA fees due Fortress (1,000 ) Gain on deconsolidation of Caelum $ 18,384

Property and Equipment (Tables)

Property and Equipment (Tables)	3 Months Ended
Property and Equipment (Tables)	Mar. 31, 2019
Property, Plant and Equipment [Abstract]
Components of Property and Equipment	Fortress’ property and equipment consisted of the following: ($ in thousands) Useful Life (Years) March 31, 2019 December 31, 2018 Computer equipment 3 $ 648 $ 648 Furniture and fixtures 5 1,142 1,128 Machinery & equipment 5 3,242 3,143 Leasehold improvements 5 15 9,359 9,271 Construction in progress 1 N/A 487 393 Total property and equipment 14,878 14,583 Less: Accumulated depreciation (3,045 ) (2,564 ) Property and equipment, net $ 11,833 $ 12,019 Note 1: Relates to the Mustang cell processing facility.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
Fair Value Measurements (Tables)	Mar. 31, 2019
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables classify into the fair value hierarchy of Fortress’ financial instruments, measured at fair value as of March 31, 2019 and December 31, 2018: Fair Value Measurement as of March 31, 2019 ($ in thousands) Level 1 Level 2 Level 3 Total Assets Fair value of investment in Caelum $ – $ – $ 11,056 $ 11,056 Total $ – $ – $ 11,056 $ 11,056 Fair Value Measurement as of December 31, 2018 ($ in thousands) Level 1 Level 2 Level 3 Total Liabilities Caelum warrant liability $ – $ – $ 991 $ 991 Caelum convertible notes, at fair value – – 9,914 9,914 Total $ – $ – $ 10,905 $ 10,905
Schedule of changes in fair value of financial instruments	The table below provides a roll-forward of the changes in fair value of Level 3 financial instruments as of March 31, 2019: Caelum ($ in thousands) Convertible Note Warrant liability Total Balance at December 31, 2018 $ 9,914 $ 991 $ 10,905 Conversion of convertible notes (9,914 ) – (9,914 ) Issuance of warrant – (991 ) (991 ) Balance at March 31, 2019 $ – $ – $ –
Caelum [Member] \| Convertible Debt [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques	A summary of the weighted average (in aggregate) significant unobservable inputs (Level 3 inputs) used in measuring Caelum’s convertible notes that are categorized within Level 3 of the fair value hierarchy as of December 31, 2018 is as follows: December 31, 2018 Risk-free interest rate 2.302 % Expected dividend yield – % Expected term in years 0.32 Expected volatility 67 %
Fair Value for Derivative Contingently Issuable Warrant Liabilities	($ in thousands) Caelum Convertible Notes, at fair value Beginning balance at January 1, 2019 $ 9,914 Conversion of the convertible notes (9,914 ) Ending balance at March 31, 2019 $ –
Warrant [Member] \| Caelum [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques	The Caelum warrant liability and convertible notes did not exist as of March 31, 2019. A summary of the weighted average (in aggregate) significant unobservable inputs (Level 3 inputs) used in measuring Caelum’s warrant liability that are categorized within Level 3 of the fair value hierarchy as of December 31, 2018 is as follows: December 31, 2018 Risk-free interest rate 2.905 2.909 % Expected dividend yield – % Expected term in years 3.84 3.96 Expected volatility 70 %
Fair Value for Derivative Contingently Issuable Warrant Liabilities	($ in thousands) Fair Value of Derivative Warrant Liability Beginning balance at January 1, 2019 $ 991 Issuance of warrant due to conversion of note (991 ) Ending balance at March 31, 2019 $ –

Licenses Acquired (Tables)

Licenses Acquired (Tables)	3 Months Ended
Licenses Acquired (Tables)	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Research and Development Arrangement, Contract to Perform for Others	As such, for the three months ended March 31, 2019 and 2018, the purchase price of licenses acquired was classified as research and development-licenses acquired in the Condensed Consolidated Statements of Operations as reflected in the table below: For the Three Months Ended March 31, ($ in thousands) 2019 2018 Partner companies: Helocyte $ – $ 21 Mustang 450 75 Cellvation – 1 Total $ 450 $ 97
Schedule Of Licenses Acquired Expenses	For the three months ended March 31, 2019 and 2018, Mustang recorded the following expense in research and development for licenses acquired: For the Three Months Ended March 31, ($ in thousands) 2019 2018 City of Hope (COH) – CD123 $ 250 $ – City of Hope manufacturing – 75 Nationwide Children’s Hospital – C134 (MB-108) 200 – Total $ 450 $ 75

Intangibles, net (Tables)

Intangibles, net (Tables)	3 Months Ended
Intangibles, net (Tables)	Mar. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The table below provides a summary of the JMC intangible asset as of March 31, 2019 and December 31, 2018, respectively: Estimated Useful March 31, December 31, ($ in thousands) Lives (in years) 2019 2018 Ceracade® 3 $ 300 $ 300 Luxamend® 3 50 50 Targadox® 3 1,250 1,250 Exelderm® 3 1,200 1,200 Total 2,800 2,800 Accumulated amortization 1,617 1,383 Net intangible assets $ 1,183 $ 1,417
Schedule of Acquired Finite-Lived Intangible Assets by Major Class	The table below provides a summary for the three months ended March 31, 2019, of JMC recognized expense related to its product licenses, which was recorded in costs of goods sold on the Condensed Consolidated Statement of Operations: ( $ in thousands) Intangible Assets Beginning balance at January 1, 2019 $ 1,417 Amortization expense (234 ) Ending balance at March 31, 2019 $ 1,183
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The future amortization of these intangible assets is as follows: Total ($ in thousands) Ceracade® Targadox® Exelderm® Amortization For the nine-months ending December 31, 2019 $ 8 $ 208 $ 300 $ 516 December 31, 2020 – – 400 400 December 31, 2021 – – 267 267 Total $ 8 $ 208 $ 967 $ 1,183

Debt and Interest (Tables)

Debt and Interest (Tables)	3 Months Ended
Debt and Interest (Tables)	Mar. 31, 2019
Debt Disclosure [Abstract]
Schedule Of Interest Expenses	Total debt consists of the following as of March 31, 2019 and December 31, 2018: ($ in thousands) March 31, 2019 December 31, 2018 Interest rate Maturity IDB Note $ 14,929 $ 14,929 2.25 % Aug - 2020 2017 Subordinated Note Financing 3,254 3,254 8.00 % March - 2020 2017 Subordinated Note Financing 13,893 13,893 8.00 % May - 2020 2017 Subordinated Note Financing 1,820 1,820 8.00 % June - 2020 2017 Subordinated Note Financing 3,018 3,018 8.00 % August - 2020 2017 Subordinated Note Financing 6,371 6,371 8.00 % September - 2020 2018 Venture Debt 6,517 6,517 8.00 % February - 2021 2018 Venture Debt 15,190 15,190 8.00 % March - 2021 Opus Credit Facility 1 9,500 9,500 12.00 % September - 2019 Mustang Horizon Notes 2 15,000 – 9.00 % October - 2022 Caelum Convertible Note, at fair value 1 – 1,000 8.00 % January - 2019 Caelum Convertible Note, at fair value 1 – 6,800 8.00 % February - 2019 Caelum Convertible Note, at fair value 1 – 2,114 8.00 % March - 2019 Total notes payable 89,492 84,406 Less: Discount on notes payable 6,608 4,903 Total notes payable $ 82,884 $ 79,503 Note 1: Classified as short-term on the Company’s Consolidated Balance Sheet as of December 31, 2018. Note 2: Interest rate is 9.0% plus one-month LIBOR Rate 2.5
Schedule Of Interest Expenses For Debt Arrangements	The following table shows the details of interest expense for all debt arrangements during the periods presented. Interest expense includes contractual interest and amortization of the debt discount and amortization of fees represents fees associated with loan transaction costs, amortized over the life of the loan: Three Months Ended March 31, 2019 2018 ($ in thousands) Interest Fees 1 Total Interest Fees 1 Total IDB Note $ 83 $ - $ 83 $ 84 $ - $ 84 2017 Subordinated Note Financing 1,028 363 1,391 1,048 325 1,373 Opus Credit Facility 281 113 394 281 319 600 2018 Venture Notes 429 146 575 56 17 73 LOC Fees 15 – 15 7 – 7 Helocyte Convertible Note – – – 68 – 68 Caelum Convertible Note – – – 196 – 196 Mustang Horizon Notes 11 – 11 – – – Other – – – 2 – 2 Total Interest Expense and Financing Fee $ 1,847 $ 622 $ 2,469 $ 1,742 $ 661 $ 2,403 Note 1: amortization of fees

Leases (Tables)

Leases (Tables)	3 Months Ended
Leases (Tables)	Mar. 31, 2019
Leases [Abstract]
Schedule of Lease, Cost	During the three months ended March 31, 2019, the Company recorded $0.8 million as lease expense to current period operations. As of ($ in thousands) March 31, 2019 Lease cost Operating lease cost $ 796 Shared lease costs (477 ) Variable lease cost 26 Total lease cost $ 345 The following tables summarize quantitative information about the Company’s operating leases, under the adoption of Topic 842 ($ in thousands) Three Months Ended March 31, 2019 Operating cash flows from operating leases $ (767 ) Right-of-use assets exchanged for new operating lease liabilities $ 22,618 Weighted-average remaining lease term – operating leases (years) 6.7 Weighted-average discount rate – operating leases 6.2 % ($ in thousands) Future Lease Nine months ended December 31, 2019 $ 1,871 Year ended December 31, 2020 3,351 Year ended December 31, 2021 3,114 Year ended December 31, 2022 3,084 Year ended December 31, 2023 3,137 Other 23,463 Total operating lease liabilities 38,020 Less: present value discount (11,550 ) Net operating lease liabilities, short-term and long-term $ 26,470
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	At December 31, 2018, the total future minimum lease payments under all leases were: ($ in thousands) 2019 $ 3,070 2020 3,289 2021 3,084 2022 3,084 2023 3,137 Beyond 23,466 Total minimum lease payments $ 39,130

Accrued Liabilities and other_2

Accrued Liabilities and other Long-Term Liabilities (Tables)	3 Months Ended
	Mar. 31, 2019
Payables and Accruals [Abstract]
Components of Accrued Expenses and Other Long-Term Liabilities	Accrued expenses and other long-term liabilities consisted of the following: ($ in thousands) March 31, 2019 December 31, 2018 Accrued expenses: Professional fees $ 1,262 $ 1,434 Salaries, bonuses and related benefits 5,592 5,843 Accrued expenses - related party 16 – Research and development 4,855 3,805 Research and development - milestones – 200 Research and development - manufacturing 826 826 Research and development - clinical supplies 215 160 Research and development - license maintenance fees 489 519 Dr. Falk Pharma settlement 300 300 Accrued royalties payable 1,233 1,108 Accrued coupon expense 993 838 Other 4,546 1,327 Total accrued expenses $ 20,327 $ 16,360 Other long-term liabilities: Deferred expenses related to build-out 1 2,276 5,211 Total other long-term liabilities $ 2,276 $ 5,211 Note 1: As of March 31, 2019, balance consists of deferred charges related to build-out of the New York facility, and as of December 31, 2018, balance consists of deferred rent and deferred build out charges.

Non-Controlling Interests (Tabl

Non-Controlling Interests (Tables)	3 Months Ended
Non-Controlling Interests (Tables)	Mar. 31, 2019
Noncontrolling Interest [Abstract]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net	Non-controlling interests in consolidated entities are as follows: For the three months ended As of March 31, 2019 March 31, 2019 As of March 31, 2019 ($ in thousands) NCI equity share Net loss attributable to non- controlling interests Non-controlling interests in consolidated entities Non-controlling ownership Aevitas $ (1,125 ) $ (138 ) $ (1,263 ) 36.1 % Avenue 2 23,702 (8,000 ) (15,702 ) 77.2 % Caelum 3 – – – 60.1 % Cellvation (670 ) (53 ) (723 ) 21.1 % Checkpoint 1 8,754 (3,932 ) 4,822 68.1 % Coronado SO (290 ) – (290 ) 13.0 % Cyprium (279 ) (43 ) (322 ) 10.6 % Helocyte (4,045 ) (48 ) (4,093 ) 19.3 % JMC (227 ) 24 (203 ) 6.9 % Mustang 2 22,211 (5,419 ) 16,792 58.9 % Tamid (492 ) (38 ) (530 ) 23.4 % Total $ 47,539 $ (17,647 ) $ 29,892 For the twelve months ended As of December 31, 2018 December 31, 2018 As of December 31, 2018 ($ in thousands) NCI equity share Net loss attributable to non- controlling interests Non-controlling interests in consolidated entities Non-controlling ownership Aevitas $ (474 ) $ (606 ) $ (1,080 ) 36.1 % Avenue 2 13,326 (13,735 ) (409 ) 64.81 % Caelum (2,436 ) (2,413 ) (4,849 ) 36.8 % Cellvation (457 ) (185 ) (642 ) 21.1 % Checkpoint 1 31,648 (23,470 ) 8,178 69.3 % Coronado SO (290 ) – (290 ) 13.0 % Cyprium (210 ) (62 ) (272 ) 10.8 % Helocyte (3,372 ) (684 ) (4,056 ) 19.8 % JMC (475 ) 245 (230 ) 6.9 % Mustang 2 38,631 (16,628 ) 22,003 60.5 % Tamid (211 ) (251 ) (462 ) 23.4 % Total $ 75,680 $ (57,789 ) $ 17,891 Note 1: Checkpoint is consolidated with Fortress’ operations because Fortress maintains voting control through its ownership of Checkpoint’s Class A Common Shares which provide super-majority voting rights. Note 2: Avenue and Mustang are consolidated with Fortress’ operations because Fortress maintains voting control through its ownership of Preferred Class A Shares which provide super-majority voting rights. Note 3: Effective January 30, 2019, Caelum ceased to be a controlled Fortress entity and as such is no longer consolidated.

Net Income (Loss) per Common _2

Net Income (Loss) per Common Share (Tables)	3 Months Ended
Net Income (Loss) per Common Share (Tables)	Mar. 31, 2019
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table sets forth the computation of earnings per share (amounts in thousands except share and per share data): Three Months Ended March 31, 2019 2018 Net income (loss) attributable to common stockholders $ 1,392 $ (21,018 ) Weighted average shares outstanding - basic 48,506,994 42,518,403 Preferred stock, Series A 1,000,000 – Stock options 378,835 – Warrants 60,000 – Unvested restricted stock 12,622,076 – Unvested restricted stock units 1,243,231 – Weighted average shares outstanding - diluted 63,811,136 42,518,403 Per share data: Basic $ 0.03 $ (0.49 ) Diluted $ 0.02 $ (0.49 )
Computations of Diluted Weighted Average Shares Outstanding	The following shares of potentially dilutive securities have been excluded from the computations of diluted weighted average shares outstanding, as the effect of including such securities would be anti-dilutive at the end of the three months ended March 31, 2018: March 31, 2018 Warrants to purchase Common Stock 894,189 Opus warrants to purchase Common Stock 1,880,000 Options to purchase Common Stock 1,085,501 Convertible Preferred Stock 1,000,000 Unvested Restricted Stock 11,050,943 Unvested Restricted Stock Units 1,778,154 Total 17,688,787

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
Stockholders' Equity (Tables)	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Share-based Compensation, Activity	The following table summarizes the stock-based compensation expense from stock option, employee stock purchase programs and restricted Common Stock awards and warrants for the three months ended March 31, 2019 and 2018: For the Three Months Ended March 31, ($ in thousands) 2019 2018 Employee awards $ 935 $ 942 Executive awards of Fortress partner companies’ stock 352 518 Non-employee awards (2 ) 23 Fortress partner companies: Avenue 751 349 Checkpoint 798 1,137 Mustang 432 1,995 Other 43 (169 ) Total stock-based compensation $ 3,309 $ 4,795
Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Outstanding And Exercisable	The following table summarizes Fortress stock option activities excluding activity related to Fortress partner companies: Number of shares Weighted average exercise price Total weighted average intrinsic value Weighted average remaining contractual life (years) Options vested and expected to vest at December 31, 2018 1,085,501 $ 3.75 $ – 2.93 Exercised – – – – Options vested and expected to vest at March 31, 2019 1,085,501 $ 3.75 $ 155,322 2.68 Options vested and exercisable 1,085,501 $ 3.75 $ 155,322 2.68
Nonvested Restricted Stock Shares Activity	The following table summarizes Fortress restricted stock awards and restricted stock units activities, excluding activities related to Fortress Companies: Number of shares Weighted average grant price Unvested balance at December 31, 2018 12,645,982 $ 2.72 Restricted stock granted 1,516,408 0.86 Restricted stock vested (220,000 ) 2.82 Restricted stock units forfeited (43,333 ) 4.56 Restricted stock units vested (33,750 ) 3.59 Unvested balance at March 31, 2019 13,865,307 $ 2.51
Schedule of Warrant Activities	The following table summarizes Fortress warrant activities, excluding activities related to Fortress Companies: Number of shares Weighted average exercise price Total weighted average intrinsic value Weighted average remaining contractual life (years) Outstanding as of December 31, 2018 2,754,189 $ 3.28 $ – 3.49 Granted – – – – Forfeited – – – – Outstanding as of March 31, 2019 2,754,189 $ 3.28 $ 24,600 3.25 Exercisable as of March 31, 2019 849,189 $ 3.92 $ 24,600 2.89

Related Party Transactions (Tab

Related Party Transactions (Tables)	3 Months Ended
Related Party Transactions (Tables)	Mar. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of Effective Date and Equity Fee Payable	The Company has entered into Founders Agreements and, in some cases, Exchange Agreements with certain of its subsidiaries as described in the Company’s Form 10-K for the year ended December 31, 2018, filed with the SEC on March 18, 2019. The following table summarizes, by subsidiary, the effective date of the Founders Agreements and PIK dividend or equity fee payable to the Company in accordance with the terms of the Founders Agreements, Exchange Agreements and the subsidiaries’ certificates of incorporation. Fortress Partner Company Effective Date (1) PIK Dividend as a % of fully diluted outstanding capitalization Class of Stock Issued Helocyte March 20, 2015 2.5 % Common Stock Avenue February 17, 2015 0.0 % (2) Common Stock Mustang March 13, 2015 2.5 % Common Stock Checkpoint March 17, 2015 0.0 % (3) Common Stock Cellvation October 31, 2016 2.5 % Common Stock Caelum January 1, 2017 0.0 % (4) Common Stock Cyprium March 13, 2017 2.5 % Common Stock Aevitas July 28, 2017 2.5 % Common Stock Tamid November 30, 2017 (5) 2.5 % Common Stock Note 1: Represents the effective date of each subsidiary’s Founders Agreement. Each PIK dividend and equity fee is payable on the annual anniversary of the effective date of the original Founders Agreement or has since been amended to January 1 of each calendar year. Note 2: Concurrently with the execution and delivery of the Stock Purchase and Merger Agreement (“SPMA”) entered into between, Avenue, the Company and InvaGen Pharmaceuticals Inc. (“InvaGen”) (together, the “SPMA Parties”), the SPMA Parties entered into a waiver agreement (the “Waiver Agreement”), pursuant to which the Company irrevocably waived its right to receive the annual dividend of Avenue’s common shares under the terms of the Class A preferred stock and any fees, payments, reimbursements or other distributions under the management services agreement between the Company and Avenue and the Founders Agreement, for the period from the effective date of the Waiver Agreement to the termination of InvaGen’s rights under the SPMA. Pursuant to the Waiver Agreement, immediately prior to the closing of the Merger Transaction contemplated under the SPMA, the Company will convert all of its preferred shares into common shares pursuant to the terms of the certificate of incorporation of Avenue, as amended from time to time. Note 3: Instead of a PIK dividend, Checkpoint pays the Company an annual equity fee in shares of Checkpoint’s common stock equal to 2.5% of Checkpoint’s fully diluted outstanding capitalization. Note 4: Effective January 31, 2019 the Caelum Founders Agreement and MSA with Fortress were terminated in conjunction with the execution of a Development Option and Share Purchase Agreement (“DOSPA”) between Caelum and Alexion Therapeutics, Inc. (See Note 4). Note 5: Represents the Trigger Date, the date that the Fortress partner company first acquires, whether by license or otherwise, ownership rights in a product.
Schedule of Effective Date and Annual Management Services Agreement Fee income expense	The Company has entered in Management Services Agreements (the “MSAs”) with certain of its subsidiaries as described in the Company’s Form 10-K for the year ended December 31, 2018, filed with the SEC on March 18, 2019. The following table summarizes, by subsidiary, the effective date of the MSA and the annual consulting fee payable by the subsidiary to the Company in quarterly installments: Fortress partner company Effective Date Annual MSA Fee (Income)/Expense Helocyte March 20, 2015 $ 500 Avenue (1) February 17, 2015 – Mustang March 13, 2015 500 Checkpoint March 17, 2015 500 Cellvation October 31, 2016 500 Caelum (2) January 1, 2017 – Cyprium March 13, 2017 500 Aevitas July 28, 2017 500 Tamid November 30, 2017 500 Fortress (3,500 ) Consolidated (Income)/Expense $ – Note 1: Concurrently with the execution and delivery of the SPMA entered into between, Avenue, the Company and InvaGen Pharmaceuticals Inc. (“InvaGen”) (together, the “SPMA Parties”), the SPMA Parties entered into a waiver agreement (the “Waiver Agreement”), pursuant to which the Company irrevocably waived its right to receive the annual dividend of Avenue’s common shares under the terms of the Class A preferred stock and any fees, payments, reimbursements or other distributions under the management services agreement between the Company and Avenue and the Founders Agreement, for the period from the effective date of the Waiver Agreement to the termination of InvaGen’s rights under the SPMA. Pursuant to the Waiver Agreement, immediately prior to the closing of the Merger Transaction contemplated under the SPMA, the Company will convert all of its preferred shares into common shares pursuant to the terms of the certificate of incorporation of Avenue, as amended from time to time. (See Note 4). Note 2: Effective January 31, 2019 the Caelum Founders Agreement and MSA with Fortress were terminated in conjunction with the execution of a DOSPA between Caelum and Alexion Therapeutics, Inc. and $1.0 million of fees accrued under the MSA were written off (See Note 4).

Segment Information (Tables)

Segment Information (Tables)	3 Months Ended
Segment Information (Tables)	Mar. 31, 2019
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	The following tables summarize, for the periods indicated, operating results, from continued operations by reportable segment: Dermatology Pharmaceutical and Biotechnology ($ in thousands) Products Product Three Months Ended March 31, 2019 Sales Development Consolidated Net Revenue $ 6,125 $ 352 $ 6,477 Direct cost of goods (1,884 ) – (1,884 ) Sales and marketing costs (3,493 ) – (3,493 ) Research and development – (23,723 ) (23,723 ) General and administrative (387 ) (9,598 ) (9,985 ) Segment income (loss) from operations $ 361 $ (32,969 ) $ (32,608 ) Segment assets $ 11,079 $ 189,459 $ 200,538 ($ in thousands) Three Months Ended March 31, 2018 Dermatology Products Sales Pharmaceutical and Biotechnology Product Development Consolidated Net Revenue $ 5,509 $ 394 $ 5,903 Direct cost of goods (1,472 ) – (1,472 ) Sales and marketing costs (2,764 ) – (2,764 ) Research and development – (25,055 ) (25,055 ) General and administrative (397 ) (10,387 ) (10,784 ) Segment income (loss) from operations $ 876 $ (35,048 ) $ (34,172 ) Segment assets $ 11,163 $ 189,560 $ 200,723 Assets held for sale 64,352 Total consolidated $ 265,075

Revenues from Contracts and S_2

Revenues from Contracts and Significant Customers (Tables)	3 Months Ended
Revenues from Contracts and Significant Customers (Tables)	Mar. 31, 2019
Revenues [Abstract]
Disaggregation of Revenue	Revenues by product and collaborator are summarized as follows (in thousands): Three months ended March 31, 2019 2018 Targadox® $ 5,700 $ 5,498 Other branded revenue 425 11 Total product revenues $ 6,125 $ 5,509 TGTX 352 394 Total Revenue $ 6,477 $ 5,903

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
Accounting Policies [Line Items]
Operating Lease, Liability	$ 26,470
Operating Lease, Right-of-Use Asset	$ 22,618
Accounting Standards Update 2016-02 [Member]
Accounting Policies [Line Items]
Operating Lease, Liability		$ 26,800
Operating Lease, Right-of-Use Asset		23,000
Deferred Rent Credit		$ 3,800

Discontinued Operations- Summar

Discontinued Operations- Summary of revenue and expenses (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue		$ 49,522
Operating expenses
Commissions, compensation and fees		43,561
Clearing fees		743
Communications		760
Occupancy		955
Licenses and registration		637
Professional fees		1,393
Underwriting costs		145
Interest		2
Depreciation and amortization		859
Other administrative expenses		1,781
Total operating expenses		50,836
Gain (loss) from operations		(1,314)
Other income (expenses)
Change in fair value of derivative liabilities		(1,088)
Interest expense and financing fees		320
Interest income		6
Total other expenses		(762)
Total loss from discontinued operations	$ 0	$ (2,076)

Discontinued Operations- Classi

Discontinued Operations- Classified assets and liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 31, 2019	Dec. 31, 2018
Current assets
Current assets held for sale			$ 13,089
Total current assets held for sale		$ 1,207	13,089
Total assets held for sale			$ 13,089

Discontinued Operations- Cash f

Discontinued Operations- Cash flows from the transaction (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating activities
Effect of elimination entry on discontinued operations presentation		$ (305)
Net loss on discontinued operations	0	(2,076)
Total cash used in discontinued operating activities		$ (2,381)
Investing activities
Proceeds from sale of National	13,089
Total cash provided by discontinued investing activities	$ 13,089

Discontinued Operations- Additi

Discontinued Operations- Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Disposal Group, Including Discontinued Operation, Assets		$ 13,089
National Holdings Corporation [Member]
Disposal Group, Including Discontinued Operation, Assets	$ 13,100
Share Price	$ 3.25

Collaboration and Stock Purch_3

Collaboration and Stock Purchase Agreements - Summary of the assets and liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 31, 2019	Dec. 31, 2018
Current assets
Cash and cash equivalents		$ 1,201
Prepaid expenses and other current assets		6
Total current assets held for sale		1,207	$ 13,089
Current liabilities
Accounts payable and accrued expenses		2,246
Interest payable		198
Interest payable - related party		106
Note payable - related party		929
Note payable		9,914
Warrant liability		991
Other current liabilities		14,384
Net liabilities impacted by deconsolidation	$ 13,177	$ 13,177

Collaboration and Stock Purch_4

Collaboration and Stock Purchase Agreements - Condensed consolidated financial statements (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Jan. 31, 2019
Gain on deconsolidation of Caelum
Fair value of Caelum	$ 11,056
Net liabilities deconsolidated	13,177	$ 13,177
Non-controlling interest share	(4,849)
Write off of MSA fees due Fortress	(1,000)
Gain on deconsolidation of Caelum	$ 18,384

Collaboration and Stock Purch_5

Collaboration and Stock Purchase Agreements - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended
	Feb. 08, 2019	Jan. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Nov. 12, 2018
Revenues			$ 6,477	$ 5,903
Business Acquisition, Percentage of Voting Interests Acquired					33.30%
Business Combination, Contingent Consideration, Liability					$ 180,000
Contingent Earn Out Payments Measurement Second Model			at any time beginning on January 1, 2029 that IV Tramadol has generated at least $1.5 billion in aggregate Net Sales, then with respect to each calendar year in which IV Tramadol generates $100 million or more in Net Sales, each Holder shall be entitled to receive their pro rata share of an amount equal to 20% of the Gross Profit generated by IV Tramadol
Caelum [Member]
Sale of Stock, Consideration Received on Transaction		$ 30,000
Sale of Stock Percentage of Shares Transferred on Transaction		19.90%
Sales [Member] \| Avenue [Member]
Revenues			$ 325,000
Slab One [Member] \| Avenue [Member]
Gross Profit Percentage To Net Sales			10.00%
Slab One [Member] \| Sales [Member] \| Avenue [Member]
Revenues			$ 400,000
Slab Two [Member] \| Avenue [Member]
Gross Profit Percentage To Net Sales			12.50%
Slab Two [Member] \| Sales [Member] \| Avenue [Member] \| Maximum [Member]
Revenues			$ 500,000
Slab Two [Member] \| Sales [Member] \| Avenue [Member] \| Minimum [Member]
Revenues			$ 400,000
Slab Three [Member] \| Avenue [Member]
Gross Profit Percentage To Net Sales			15.00%
Slab Three [Member] \| Sales [Member] \| Avenue [Member]
Revenues			$ 500,000
SPMA [Member]
Business Combination, Consideration Transferred	$ 7,000
First Stage Member [Member] \| SPMA [Member]
Business Combination, Consideration Transferred	$ 31,500

Property and Equipment - Compon

Property and Equipment - Components of Property and Equipment (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total property and equipment		$ 14,878	$ 14,583
Less: Accumulated depreciation		(3,045)	(2,564)
Property and equipment, net		11,833	12,019
Computer Equipment [Member] \| Fortress Biotech Inc [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment		$ 648	648
Useful Life (Years)		3 years
Furniture and Fixtures [Member] \| Fortress Biotech Inc [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment		$ 1,142	1,128
Useful Life (Years)		5 years
Leasehold Improvements [Member] \| Fortress Biotech Inc [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment		$ 9,359	9,271
Leasehold Improvements [Member] \| Fortress Biotech Inc [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Useful Life (Years)		15 years
Leasehold Improvements [Member] \| Fortress Biotech Inc [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Useful Life (Years)		5 years
Construction in progress [Member] \| Fortress Biotech Inc [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	[1]	$ 487	393
Machinery and Equipment [Member] \| Fortress Biotech Inc [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment		$ 3,242	$ 3,143
Useful Life (Years)		5 years

[1]	Relates to the Mustang cell processing facility.

Property and Equipment - Additi

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Property, Plant and Equipment [Line Items]
Depreciation	$ 481	$ 196

Fair Value Measurements - Conti

Fair Value Measurements - Contingently Issuable Warrants with option pricing model (Detail) - Caelum Warrant Liabilities [Member]	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Measurement Input, Risk Free Interest Rate [Member] \| Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Risk-free interest rate		2.905%
Measurement Input, Risk Free Interest Rate [Member] \| Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Risk-free interest rate		2.909%
Measurement Input, Expected Dividend Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected dividend yield	0.00%	0.00%
Measurement Input, Expected Term [Member] \| Minimum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected term in years		3 years 10 months 2 days
Measurement Input, Expected Term [Member] \| Maximum [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected term in years		3 years 11 months 15 days
Measurement Input, Price Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected volatility		70.00%

Fair Value Measurements - Deriv

Fair Value Measurements - Derivative Contingently Issuable Warrant liabilities (Detail) - Caelum Warrant Liabilities [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Beginning balance	$ 991
Issuance of warrant due to conversion of note	(991)
Ending balance	$ 0

Fair Value Measurements - Warra

Fair Value Measurements - Warrant Liabilities And Convertible Notes At Fair Value (Detail) - Caelum Convertible Notes [Member]	12 Months Ended
	Dec. 31, 2018
Measurement Input, Risk Free Interest Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Risk-free interest rate	2.302%
Measurement Input, Expected Dividend Rate [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected dividend yield	0.00%
Measurement Input, Expected Term [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected term in years	3 months 25 days
Measurement Input, Price Volatility [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected volatility	67.00%

Fair Value Measurements - Exclu

Fair Value Measurements - Exclusive of National Financial Instruments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets
Fair value of investment in Caelum	$ 11,056
Total	11,056
Liabilities
Liabilities		$ 10,905
Warrant [Member]
Liabilities
Liabilities		991
Caelum Convertible Notes [Member]
Liabilities
Liabilities		9,914
Fair Value, Inputs, Level 1 [Member]
Assets
Fair value of investment in Caelum	0
Total	0
Liabilities
Liabilities		0
Fair Value, Inputs, Level 1 [Member] \| Warrant [Member]
Liabilities
Liabilities		0
Fair Value, Inputs, Level 1 [Member] \| Caelum Convertible Notes [Member]
Liabilities
Liabilities		0
Fair Value, Inputs, Level 2 [Member]
Assets
Fair value of investment in Caelum	0
Total	0
Liabilities
Liabilities		0
Fair Value, Inputs, Level 2 [Member] \| Warrant [Member]
Liabilities
Liabilities		0
Fair Value, Inputs, Level 2 [Member] \| Caelum Convertible Notes [Member]
Liabilities
Liabilities		0
Fair Value, Inputs, Level 3 [Member]
Assets
Fair value of investment in Caelum	11,056
Total	$ 11,056
Liabilities
Liabilities		10,905
Fair Value, Inputs, Level 3 [Member] \| Warrant [Member]
Liabilities
Liabilities		991
Fair Value, Inputs, Level 3 [Member] \| Caelum Convertible Notes [Member]
Liabilities
Liabilities		$ 9,914

Fair Value Measurements - Chang

Fair Value Measurements - Changes in Fair Value of Financial Instruments (Detail) - Caelum [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance	$ 10,905
Balance	0
Caelum Convertible Notes [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Balance	9,914
Conversion of the convertible notes	(9,914)
Balance	$ 0

Fair Value Measurements - Cha_2

Fair Value Measurements - Changes in fair value (Detail) - Caelum [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Balance	$ 10,905
Conversion of convertible notes	(9,914)
Issuance of warrant	(991)
Balance	0
Warrant [Member]
Balance	991
Conversion of convertible notes	0
Issuance of warrant	(991)
Balance	0
Caelum Convertible Notes [Member]
Balance	9,914
Conversion of convertible notes	(9,914)
Issuance of warrant	0
Balance	$ 0

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)$ / shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	$ 11,056
Measurement Input, Risk Free Interest Rate [Member] \| Caelum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Values Assumptions Risk Free Return	2.24%
Measurement Input Investments [Member] \| Caelum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments, Fair Value Disclosure	$ 11,100
Measurement Input, Share Price [Member] \| Caelum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Values Assumptions Share Price \| $ / shares	$ 1.549
Measurement Input, Price Volatility [Member] \| Caelum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Values Assumptions Expected Volatility Rate	70.00%
Fair Values Assumptions Expected Discount For Lack Of Marketability	27.90%

Licenses Acquired - Summary Of

Licenses Acquired - Summary Of Research and Development Arrangement Contract (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Total	$ 450	$ 97
Cellvation [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Total	0	1
Helocyte [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Total	0	21
Mustang [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development Total	$ 450	$ 75

Licenses Acquired - license as

Licenses Acquired - license as recorded in the Condensed Consolidated Statements of Operations (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process	$ 450	$ 97
Mustang Therapeutics, Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process	450	75
Mustang Therapeutics, Inc [Member] \| City of Hope COH CD123 [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process	250	0
Mustang Therapeutics, Inc [Member] \| City Of Hope Manufacturing [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process	0	75
Mustang Therapeutics, Inc [Member] \| Nationwide Childrens Hospital [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and Development in Process	$ 200	$ 0

Licenses Acquired - Additional

Licenses Acquired - Additional Information (Detail) - Nationwide Childrens Hospital [Member] $ in Millions	Feb. 01, 2019USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Payment For Research And Development Licenses	$ 0.2
Research And Development Licenses Payments Due	$ 152.8

Intangibles, net - Summary Of T

Intangibles, net - Summary Of The JMC Intangible Asset (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Net intangible assets	$ 1,183	$ 1,417
Journey Medical Corporation [Member]
Finite-Lived Intangible Assets, Gross	2,800	2,800
Accumulated amortization	1,617	1,383
Net intangible assets	$ 1,183	1,417
Ceracade [Member] \| Journey Medical Corporation [Member]
Finite-Lived Intangible Asset, Useful Life	3 years
Finite-Lived Intangible Assets, Gross	$ 300	300
Luxamend [Member] \| Journey Medical Corporation [Member]
Finite-Lived Intangible Asset, Useful Life	3 years
Finite-Lived Intangible Assets, Gross	$ 50	50
Targadox [Member] \| Journey Medical Corporation [Member]
Finite-Lived Intangible Asset, Useful Life	3 years
Finite-Lived Intangible Assets, Gross	$ 1,250	1,250
Exelderm [Member] \| Journey Medical Corporation [Member]
Finite-Lived Intangible Asset, Useful Life	3 years
Finite-Lived Intangible Assets, Gross	$ 1,200	$ 1,200

Intangibles, net - Cost Of Good

Intangibles, net - Cost Of Goods Sold (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Beginning balance at January 1, 2019	$ 1,417
Ending balance at March 31, 2019	1,183
Journey Medical Corporation [Member]
Beginning balance at January 1, 2019	1,417
Amortization expense	(234)
Ending balance at March 31, 2019	$ 1,183

Intangibles, net - Amortization

Intangibles, net - Amortization Of Intangible Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Total	$ 1,183	$ 1,417
Journey Medical Corporation [Member]
For the nine-months ending December 31, 2019	516
Year Ended December 31, 2020	400
Year Ended December 31, 2021	267
Total	1,183	$ 1,417
Ceracade [Member] \| Journey Medical Corporation [Member]
For the nine-months ending December 31, 2019	8
Year Ended December 31, 2020	0
Year Ended December 31, 2021	0
Total	8
Targadox [Member] \| Journey Medical Corporation [Member]
For the nine-months ending December 31, 2019	208
Year Ended December 31, 2020	0
Year Ended December 31, 2021	0
Total	208
Exelderm [Member] \| Journey Medical Corporation [Member]
For the nine-months ending December 31, 2019	300
Year Ended December 31, 2020	400
Year Ended December 31, 2021	267
Total	$ 967

Debt and Interest - Long-term d

Debt and Interest - Long-term debt (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Dec. 31, 2018
Debt [Line Items]
Total notes payable, long-term		$ 89,492	$ 84,406
Less: Discount of notes payable		6,608	4,903
Total notes payable		$ 82,884	79,503
Interest Rate		2.50%
IDB Note [Member]
Debt [Line Items]
Total notes payable, long-term		$ 14,929	14,929
Interest Rate		2.25%
Maturity Date		Aug - 2020
2017 Subordinated Note Financing One [Member]
Debt [Line Items]
Total notes payable, long-term		$ 3,254	3,254
Interest Rate		8.00%
Maturity Date		March - 2020
2017 Subordinated Note Financing Two [Member]
Debt [Line Items]
Total notes payable, long-term		$ 13,893	13,893
Interest Rate		8.00%
Maturity Date		May - 2020
2017 Subordinated Note Financing Three [Member]
Debt [Line Items]
Total notes payable, long-term		$ 1,820	1,820
Interest Rate		8.00%
Maturity Date		June - 2020
2017 Subordinated Note Financing Four [Member]
Debt [Line Items]
Total notes payable, long-term		$ 3,018	3,018
Interest Rate		8.00%
Maturity Date		August - 2020
2017 Subordinated Note Financing Five [Member]
Debt [Line Items]
Total notes payable, long-term		$ 6,371	6,371
Interest Rate		8.00%
Maturity Date		September - 2020
Opus Credit Facility [Member]
Debt [Line Items]
Total notes payable, long-term	[1]	$ 9,500	9,500
Interest Rate	[1]	12.00%
Maturity Date	[1]	September - 2019
Caelum Convertible Note One [Member]
Debt [Line Items]
Total notes payable, long-term	[1]	$ 0	1,000
Interest Rate	[1]	8.00%
Maturity Date	[1]	January - 2019
Caelum Convertible Note Two [Member]
Debt [Line Items]
Total notes payable, long-term	[1]	$ 0	6,800
Interest Rate	[1]	8.00%
Maturity Date	[1]	February - 2019
Caelum Convertible Note Three [Member]
Debt [Line Items]
Total notes payable, long-term	[1]	$ 0	2,114
Interest Rate	[1]	8.00%
Maturity Date	[1]	March - 2019
Venture Notes One [Member]
Debt [Line Items]
Total notes payable, long-term		$ 6,517	6,517
Interest Rate		8.00%
Maturity Date		February - 2021
Venture Notes Two [Member]
Debt [Line Items]
Total notes payable, long-term		$ 15,190	15,190
Interest Rate		8.00%
Maturity Date		March - 2021
Mustang 2019 Venture Debt [Member]
Debt [Line Items]
Total notes payable, long-term	[2]	$ 15,000	$ 0
Interest Rate	[2]	9.00%
Maturity Date	[2]	October - 2022

[1]	Classified as short-term on the Company’s Consolidated Balance Sheet as of December 31, 2018.
[2]	Interest rate is 9.0% plus one-month LIBOR Rate in excess of 2.5%

Debt and Interest - Schedule of

Debt and Interest - Schedule of Interest Expenses for Debt Arrangements (Detail) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Debt [Line Items]
Interest		$ 1,847	$ 1,742
Amortization of fees	[1]	622	661
Interest and Debt Expense		2,469	2,403
LOC Fees [Member]
Debt [Line Items]
Interest		15	7
Interest and Debt Expense		15	7
IDB Note [Member]
Debt [Line Items]
Interest		83	84
Amortization of fees	[1]	0	0
Interest and Debt Expense		83	84
2017 Subordinated Note [Member]
Debt [Line Items]
Interest		1,028	1,048
Amortization of fees	[1]	363	325
Interest and Debt Expense		1,391	1,373
Opus Credit Facility [Member]
Debt [Line Items]
Interest		281	281
Amortization of fees	[1]	113	319
Interest and Debt Expense		394	600
Helocyte Convertible Note [Member]
Debt [Line Items]
Interest			68
Interest and Debt Expense			68
Caelum Convertible Note [Member]
Debt [Line Items]
Interest			196
Interest and Debt Expense			196
Other [Member]
Debt [Line Items]
Interest			2
Interest and Debt Expense			2
2018 Venture Notes [Member]
Debt [Line Items]
Interest		429	56
Amortization of fees	[1]	146	17
Interest and Debt Expense		575	$ 73
Mustang 2019 Venture Notes [Member]
Debt [Line Items]
Interest		11
Interest and Debt Expense		$ 11

[1]	amortization of fees

Debt and Interest- Additional I

Debt and Interest- Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended
	Mar. 29, 2019	Mar. 31, 2019
Debt [Line Items]
Debt Instrument, Interest Rate, Stated Percentage		2.50%
Debt Instrument, Description of Variable Rate Basis		9.0% plus one-month LIBOR Rate
Debt Instrument, Redemption, Description	At its option, upon ten business days’ prior written notice to Horizon, Mustang may prepay all or any portion greater than or equal to $500,000 of each of the outstanding advances by paying the entire principal balance (or portion thereof) and all accrued and unpaid interest, subject to a prepayment charge of 4.0% of the then outstanding principal balance of each advance if such advance is prepaid on or before the Loan Amortization Date (as defined in the Loan Agreement), 3% if such advance is prepaid after the Loan Amortization Date applicable to such Loan, but on or prior to twelve months following the Loan Amortization Date, and 2% thereafter. In addition, a final payment equal to $0.3 million for each advance (i.e., $0.8 million in aggregate with respect to the initial $15.0 million) is due on the maturity date or other date of payment in full. Amounts outstanding during an event of default shall be payable on demand and shall accrue interest at an additional rate of 5.0% per annum of the past due amount outstanding.
Debt Instrument, Debt Default, Description of Violation or Event of Default	The events of default under the Loan Agreement include, among other things, without limitation, and subject to customary grace periods, (1) Mustang’s failure to make any payments of principal or interest under the Loan Agreement, promissory notes or other loan documents, (2) Mustang’s breach or default in the performance of any covenant under the Loan Agreement, (3) the occurrence of a material adverse change, (4) Mustang making a false or misleading representation or warranty in any material respect, (5) Mustang’s insolvency or bankruptcy, (6) certain attachments or judgments on the Mustang’s assets, (7) the occurrence of any material default under certain agreements or obligations of Mustang involving indebtedness in excess of $0.3 million or (8) failing to maintain minimum monthly cash balances which range from approximately $8.0 to $13.0 million over the term of the loan. If an event of default occurs, Horizon is entitled to take enforcement action, including acceleration of amounts due under the Loan Agreement.
Percentage of Warrants Included in Debt	5.00%
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right	288,184
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 3.47
Warrants Not Settleable in Cash, Fair Value Disclosure	$ 900,000
Horizon Technology Finance Corporation [Member]
Debt [Line Items]
Legal Fees	1,200,000
Line of Credit Facility, Commitment Fee Amount	200,000
Reimbursement of Legal Fees	30,000
Mustang Two Thousand Nineteen Venture Debt [Member]
Debt [Line Items]
Line of Credit Facility, Current Borrowing Capacity	20,000,000
Line of Credit Facility, Maximum Borrowing Capacity	15,000,000
Line of Credit Facility, Remaining Borrowing Capacity	$ 5,000,000

Leases - summarizes quantitativ

Leases - summarizes quantitative information about the Company's operating leases (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Operating cash flows from operating leases	$ (767)
Right-of-use assets exchanged for new operating lease liabilities	$ 22,618
Weighted-average remaining lease term – operating leases (years)	6 years 8 months 12 days
Weighted-average discount rate – operating leases	6.20%
Nine months ended December 31, 2019	$ 1,871
Year ended December 31, 2020	3,351
Year ended December 31, 2021	3,114
Year ended December 31, 2022	3,084
Year ended December 31, 2023	3,137
Other	23,463
Total operating lease liabilities	38,020
Less: present value discount	(11,550)
Net operating lease liabilities, short-term and long-term	$ 26,470

Leases - lease expense (Detail)

Leases - lease expense (Detail) $ in Thousands	3 Months Ended
Leases - lease expense (Detail) $ in Thousands	Mar. 31, 2019USD ($)
Operating lease cost	$ 796
Shared lease costs	(477)
Variable lease cost	26
Total lease cost	$ 345

Leases - future minimum lease p

Leases - future minimum lease payments (Detail) $ in Thousands	Dec. 31, 2018USD ($)
2019	$ 3,070
2020	3,289
2021	3,084
2022	3,084
2023	3,137
Beyond	23,466
Total minimum lease payments	$ 39,130

Leases - Additional Information

Leases - Additional Information (Detail)	Oct. 03, 2014USD ($)	Aug. 31, 2018USD ($)ft²	Oct. 27, 2017USD ($)ft²	Jun. 30, 2017USD ($)ft²	Oct. 31, 2015USD ($)ft²	Mar. 31, 2019USD ($)
Lessee, Operating Lease, Term of Contract	15 years				5 years
Lessee Operating Lease Annual Average Rental Expense	$ 2,700,000				$ 200,000
Operating Leases, Rent Expense, Net	40,700,000					$ 16,000,000
Land Subject to Ground Leases \| ft²					6,100
Operating Lease, Liability						26,470,000
Operating Lease, Right-of-Use Asset						22,618,000
Operating Lease, Expense						$ 800,000
MASSACHUSETTS
Operating Leases, Rent Expense, Net			$ 3,600,000
Land Subject to Ground Leases \| ft²			27,043
Lessee Operating Lease Maturity Month and Year			Nov. 30, 2026
Lessee Operating Lease Base Rent Net of Abatements			$ 600,000
Lessee Operating Lease Improvements Costs			$ 3,900,000
AZERBAIJAN
Lessee Operating Lease Annual Average Rental Expense		$ 94,000		$ 55,000
Lessee, Operating Lease, Option to Extend				new-two year extension
Land Subject to Ground Leases \| ft²		3,681		2,295
Lessee Operating Lease Maturity Date				Nov. 30, 2020
OPPM [Member]
Lessee Operating Lease Annual Average Rental Expense	$ 300,000
Lessee Operating Lease Percentage Of Desk Space To Occupy	10.00%
TGTX [Member]
Lessee Operating Lease Annual Average Rental Expense	$ 1,100,000
Lessee Operating Lease Percentage Of Desk Space To Occupy	45.00%

Accrued Liabilities and other_3

Accrued Liabilities and other Long-Term Liabilities - Components of Accrued Expenses and Other Long-Term Liabilities (Detail) - USD ($) $ in Thousands		Mar. 31, 2019	Dec. 31, 2018
Accrued expenses:
Professional fees		$ 1,262	$ 1,434
Salaries, bonuses and related benefits		5,592	5,843
Accrued expenses - related party		16	0
Research and development		4,855	3,805
Research and development - milestones		0	200
Research and development - manufacturing		826	826
Research and development - clinical supplies		215	160
Research and development - license maintenance fees		489	519
Dr. Falk Pharma settlement		300	300
Accrued royalties payable		1,233	1,108
Accrued coupon expense		993	838
Other		4,546	1,327
Total accrued expenses		20,327	16,360
Other long-term liabilities:
Deferred expenses related to build-out	[1]	2,276	5,211
Total other long-term liabilities		$ 2,276	$ 5,211

[1]	As of March 31, 2019, balance consists of deferred charges related to build-out of the New York facility, and as of December 31, 2018, balance consists of deferred rent and deferred build out charges.

Non-Controlling Interests - Sum

Non-Controlling Interests - Summary Of Non-controlling Interests in Consolidated Entities (Detail) - USD ($) $ in Thousands		3 Months Ended			12 Months Ended
		Mar. 31, 2019		Mar. 31, 2018	Dec. 31, 2018
Noncontrolling Interest [Line Items]
NCI equity share		$ 47,539			$ 75,680
Net loss attributable to non-controlling interest		(17,647)		$ (17,200)	(57,789)
Non-controlling interests in consolidated entities		29,892			17,891
Aevitas [Member]
Noncontrolling Interest [Line Items]
NCI equity share		(1,125)			(474)
Net loss attributable to non-controlling interest		(138)			(606)
Non-controlling interests in consolidated entities		$ (1,263)			$ (1,080)
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		36.10%			36.10%
Avenue [Member]
Noncontrolling Interest [Line Items]
NCI equity share	[1]	$ 23,702			$ 13,326
Net loss attributable to non-controlling interest	[1]	(8,000)			(13,735)
Non-controlling interests in consolidated entities	[1]	$ (15,702)			$ (409)
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	[1]	77.20%			64.81%
Caelum [Member]
Noncontrolling Interest [Line Items]
NCI equity share		$ 0	[2]		$ (2,436)
Net loss attributable to non-controlling interest		0	[2]		(2,413)
Non-controlling interests in consolidated entities		$ 0	[2]		$ (4,849)
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		60.10%	[2]		36.80%
Cellvation [Member]
Noncontrolling Interest [Line Items]
NCI equity share		$ (670)			$ (457)
Net loss attributable to non-controlling interest		(53)			(185)
Non-controlling interests in consolidated entities		$ (723)			$ (642)
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		21.10%			21.10%
Checkpoint [Member]
Noncontrolling Interest [Line Items]
NCI equity share	[3]	$ 8,754			$ 31,648
Net loss attributable to non-controlling interest	[3]	(3,932)			(23,470)
Non-controlling interests in consolidated entities	[3]	$ 4,822			$ 8,178
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	[3]	68.10%			69.30%
Coronado SO [Member]
Noncontrolling Interest [Line Items]
NCI equity share		$ (290)			$ (290)
Net loss attributable to non-controlling interest		0			0
Non-controlling interests in consolidated entities		$ (290)			$ (290)
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		13.00%			13.00%
Cyprium [Member]
Noncontrolling Interest [Line Items]
NCI equity share		$ (279)			$ (210)
Net loss attributable to non-controlling interest		(43)			(62)
Non-controlling interests in consolidated entities		$ (322)			$ (272)
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		10.60%			10.80%
Helocyte [Member]
Noncontrolling Interest [Line Items]
NCI equity share		$ (4,045)			$ (3,372)
Net loss attributable to non-controlling interest		(48)			(684)
Non-controlling interests in consolidated entities		$ (4,093)			$ (4,056)
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		19.30%			19.80%
JMC [Member]
Noncontrolling Interest [Line Items]
NCI equity share		$ (227)			$ (475)
Net loss attributable to non-controlling interest		24			245
Non-controlling interests in consolidated entities		$ (203)			$ (230)
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		6.90%			6.90%
Mustang [Member]
Noncontrolling Interest [Line Items]
NCI equity share	[1]	$ 22,211			$ 38,631
Net loss attributable to non-controlling interest	[1]	(5,419)			(16,628)
Non-controlling interests in consolidated entities	[1]	$ 16,792			$ 22,003
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	[1]	58.90%			60.50%
Tamid [Member]
Noncontrolling Interest [Line Items]
NCI equity share		$ (492)			$ (211)
Net loss attributable to non-controlling interest		(38)			(251)
Non-controlling interests in consolidated entities		$ (530)			$ (462)
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		23.40%			23.40%

[1]	Avenue and Mustang are consolidated with Fortress’ operations because Fortress maintains voting control through its ownership of Preferred Class A Shares which provide super-majority voting rights.
[2]	Effective January 30, 2019, Caelum ceased to be a controlled Fortress entity and as such is no longer consolidated.
[3]	Checkpoint is consolidated with Fortress’ operations because Fortress maintains voting control through its ownership of Checkpoint’s Class A Common Shares which provide super-majority voting rights.

Net Income (Loss) per Common _3

Net Income (Loss) per Common Share - Computation of earnings per share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net income (loss) attributable to common stockholders	$ 1,392	$ (21,018)
Weighted average shares outstanding - basic	48,506,994	42,518,403
Preferred stock, Series A	1,000,000	0
Stock options	378,835	0
Warrants	60,000	0
Unvested restricted stock	12,622,076	0
Unvested restricted stock units	1,243,231	0
Weighted average shares outstanding - diluted	63,811,136	42,518,403
Per share data:
Basic	$ 0.03	$ (0.49)
Diluted	$ 0.02	$ (0.49)

Net Income (Loss) per Common _4

Net Income (Loss) per Common Share - Computations of Diluted Weighted Average Shares Outstanding (Detail)	12 Months Ended
	Dec. 31, 2018shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	17,688,787
Warrants to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	894,189
Opus warrants to purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	1,880,000
Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	1,085,501
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	1,000,000
Unvested Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	11,050,943
Unvested Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total of weighted average shares outstanding	1,778,154

Stockholders' Equity - Employee

Stockholders' Equity - Employee Stock Purchase Programs (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 3,309	$ 4,795
Avenue [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	751	349
Checkpoint [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	798	1,137
Mustang [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	432	1,995
Other [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	43	(169)
Employee Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	935	942
Executive Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	352	518
Non-Employee Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ (2)	$ 23

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, Options vested and expected to vest	1,085,501
Number of shares, Options exercised	0
Number of shares, Options vested and expected to vest	1,085,501	1,085,501
Number of shares, Options Exercisable	1,085,501
Weighted average exercise price, Options vested and expected to vest	$ 3.75
Weighted Average Exercise Price, Options exercised	0
Weighted average exercise price, Options vested and expected to vest	3.75
Weighted average exercise price, Options vested and exercisable	$ 3.75
Total Weighted average intrinsic value, Options vested and expected to vest	$ 155,322	$ 0
Total Weighted Average Intrinsic Value, Options exercised	0
Total weighted average intrinsic value, Exercisable	$ 155,322
Weighted average remaining contractual life (years), Options vested and expected to vest	2 years 8 months 4 days	2 years 11 months 4 days
Weighted average remaining contractual life (years), Options vested and exercisable	2 years 8 months 4 days

Stockholders' Equity - Restrict

Stockholders' Equity - Restricted Stock Activity (Detail) - Restricted Stock [Member]	3 Months Ended
	Mar. 31, 2019$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares, Unvested balance \| shares	12,645,982
Number of shares, Restricted stock granted \| shares	1,516,408
Number of shares, Restricted stock vested \| shares	(220,000)
Number of shares, Restricted stock units forfeited \| shares	(43,333)
Number of shares Restricted stock units vested \| shares	(33,750)
Number of shares, Unvested balance \| shares	13,865,307
Weighted average grant price, Unvested balance \| $ / shares	$ 2.72
Weighted average grant price, Restricted stock granted \| $ / shares	0.86
Weighted average grant price, Restricted stock vested \| $ / shares	2.82
Weighted average grant price, Restricted stock units forfeited \| $ / shares	4.56
Weighted average grant price, Restricted stock units vested \| $ / shares	3.59
Weighted average grant price, Unvested balance \| $ / shares	$ 2.51

Stockholders' Equity - Summariz

Stockholders' Equity - Summarizes Fortress warrant activities (Detail) - Warrant [Member] - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Subsidiary or Equity Method Investee [Line Items]
Number of shares, Outstanding	2,754,189
Number of shares, Granted	0
Number of shares, Forfeited	0
Number of shares, Outstanding	2,754,189	2,754,189
Number of shares, Exercisable	849,189
Weighted average exercise price, Outstanding	$ 3.28
Weighted average exercise price, Granted	0
Weighted average exercise price, Forfeited	0
Weighted average exercise price, Outstanding	3.28	$ 3.28
Weighted average exercise price, Exercisable	$ 3.92
Total weighted average instrinsic value, Outstanding	$ 24,600	$ 0
Total weighted average intrinsic value, Exercisable	$ 24,600
Weighted average remaining contractual life (years), Outstanding	3 years 3 months	3 years 5 months 26 days
Weighted average remaining contractual life, Exercisable (years)	2 years 10 months 20 days

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended
	Nov. 30, 2017	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Adjustments To Additional Paid In Capital At Market Offering Costs			$ (6,000)
Market Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Available-for-sale Securities		$ 10,200,000
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of Common Stock for At the Market Offering in shares		2,927,427	64,797
Adjustments To Additional Paid In Capital At Market Offering Costs			$ 0
Common Stock [Member] \| Market Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued, Price Per Share		$ 2.14
Proceeds from issuance of Common stock		$ 6,300,000
Issuance of Common Stock for At the Market Offering in shares		2.9
Adjustments To Additional Paid In Capital At Market Offering Costs		$ 100,000
Checkpoint Therapeutics, Inc [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Issued, Price Per Share		$ 4.05
Proceeds from issuance of Common stock		$ 400,000
Stock Issued During Period, Shares, New Issues		90,269
Percentage of Placement of Agent Fee	3.00%
Maximum Authorized Amount Of Shares To Be Sold	$ 100,000,000
Available-for-sale Securities		$ 68,600,000
Checkpoint Therapeutics, Inc [Member] \| Market Offering [Member] \| Founder Agreement [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, New Issues		2,254
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense		$ 600,000	2,300,000
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense		$ 2,700,000	$ 2,500,000
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		5 years 4 months 24 days	2 years 4 months 24 days
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options		$ 14,800,000	$ 2,500,000
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Stock Purchase Plan to eligible employees, Reckoning fair value percentage during offering period		85.00%
Common Stock issued in connection with the first ESPP offering		356,507
Allocated Share-based Compensation Expense		$ 20,000	$ 38,000
Common Stock, Capital Shares Reserved for Future Issuance		643,493

Related Party Transactions - Sc

Related Party Transactions - Schedule of Effective Date and Equity Fee Payble (Detail)	3 Months Ended
	Mar. 31, 2019
Helocyte Inc [Member]
Related Party Transaction [Line Items]
Dividends Paid in kind percentage	2.50%
Dividends Payable, Date Declared	Mar. 20, 2015	[1]
Avenue Therapeutics, Inc. [Member]
Related Party Transaction [Line Items]
Dividends Paid in kind percentage	0.00%	[2]
Dividends Payable, Date Declared	Feb. 17, 2015	[1]
Mustang Bio, Inc [Member]
Related Party Transaction [Line Items]
Dividends Paid in kind percentage	2.50%
Dividends Payable, Date Declared	Mar. 13, 2015	[1]
Checkpoint Therapeutics, Inc [Member]
Related Party Transaction [Line Items]
Dividends Paid in kind percentage	0.00%	[3]
Dividends Payable, Date Declared	Mar. 17, 2015	[1]
Cellvation Inc [Member]
Related Party Transaction [Line Items]
Dividends Paid in kind percentage	2.50%
Dividends Payable, Date Declared	Oct. 31, 2016	[1]
Caelum Bio sciences Inc [Member]
Related Party Transaction [Line Items]
Dividends Paid in kind percentage	0.00%	[4]
Dividends Payable, Date Declared	Jan. 1, 2017	[1]
Cyprium Bio sciences Inc [Member]
Related Party Transaction [Line Items]
Dividends Paid in kind percentage	2.50%
Dividends Payable, Date Declared	Mar. 13, 2017	[1]
Aevitas Inc [Member]
Related Party Transaction [Line Items]
Dividends Paid in kind percentage	2.50%
Dividends Payable, Date Declared	Jul. 28, 2017	[1]
Tamid [Member]
Related Party Transaction [Line Items]
Dividends Paid in kind percentage	2.50%
Dividends Payable, Date Declared	Nov. 30, 2017	[1],[5]

[1]	Represents the effective date of each subsidiary’s Founders Agreement. Each PIK dividend and equity fee is payable on the annual anniversary of the effective date of the original Founders Agreement or has since been amended to January 1 of each calendar year.
[2]	Concurrently with the execution and delivery of the Stock Purchase and Merger Agreement (“SPMA”) entered into between, Avenue, the Company and InvaGen Pharmaceuticals Inc. (“InvaGen”) (together, the “SPMA Parties”), the SPMA Parties entered into a waiver agreement (the “Waiver Agreement”), pursuant to which the Company irrevocably waived its right to receive the annual dividend of Avenue’s common shares under the terms of the Class A preferred stock and any fees, payments, reimbursements or other distributions under the management services agreement between the Company and Avenue and the Founders Agreement, for the period from the effective date of the Waiver Agreement to the termination of InvaGen’s rights under the SPMA. Pursuant to the Waiver Agreement, immediately prior to the closing of the Merger Transaction contemplated under the SPMA, the Company will convert all of its preferred shares into common shares pursuant to the terms of the certificate of incorporation of Avenue, as amended from time to time.
[3]	Instead of a PIK dividend, Checkpoint pays the Company an annual equity fee in shares of Checkpoint’s common stock equal to 2.5% of Checkpoint’s fully diluted outstanding capitalization.
[4]	Effective January 31, 2019 the Caelum Founders Agreement and MSA with Fortress were terminated in conjunction with the execution of a Development Option and Share Purchase Agreement (“DOSPA”) between Caelum and Alexion Therapeutics, Inc. (See Note 4).
[5]	Represents the Trigger Date, the date that the Fortress partner company first acquires, whether by license or otherwise, ownership rights in a product.

Related Party Transactions - _2

Related Party Transactions - Schedule of The Effective Date and Annual Management Services agreement Fee (Income) Expense (Detail)	3 Months Ended
	Mar. 31, 2019USD ($)
Related Party Transaction [Line Items]
Annual Management Services Agreement Fee Income expense	$ 0
Helocyte Inc [Member]
Related Party Transaction [Line Items]
Annual Management Services Agreement Fee Income expense	$ 500
Annual Consulting Fee Payable Effective Date	Mar. 20, 2015
Avenue Therapeutics, Inc. [Member]
Related Party Transaction [Line Items]
Annual Management Services Agreement Fee Income expense	$ 0	[1]
Annual Consulting Fee Payable Effective Date	Feb. 17, 2015	[1]
Mustang Bio, Inc [Member]
Related Party Transaction [Line Items]
Annual Management Services Agreement Fee Income expense	$ 500
Annual Consulting Fee Payable Effective Date	Mar. 13, 2015
Checkpoint Therapeutics, Inc [Member]
Related Party Transaction [Line Items]
Annual Management Services Agreement Fee Income expense	$ 500
Annual Consulting Fee Payable Effective Date	Mar. 17, 2015
Cellvation Inc [Member]
Related Party Transaction [Line Items]
Annual Management Services Agreement Fee Income expense	$ 500
Annual Consulting Fee Payable Effective Date	Oct. 31, 2016
Caelum Bio sciences Inc [Member]
Related Party Transaction [Line Items]
Annual Management Services Agreement Fee Income expense	$ 0	[2]
Annual Consulting Fee Payable Effective Date	Jan. 1, 2017	[2]
Cyprium Bio sciences Inc [Member]
Related Party Transaction [Line Items]
Annual Management Services Agreement Fee Income expense	$ 500
Annual Consulting Fee Payable Effective Date	Mar. 13, 2017
Aevitas Inc [Member]
Related Party Transaction [Line Items]
Annual Management Services Agreement Fee Income expense	$ 500
Annual Consulting Fee Payable Effective Date	Jul. 28, 2017
Tamid Bio sciences Inc [Member]
Related Party Transaction [Line Items]
Annual Management Services Agreement Fee Income expense	$ 500
Annual Consulting Fee Payable Effective Date	Nov. 30, 2017
Fortress Biotech Inc [Member]
Related Party Transaction [Line Items]
Annual Management Services Agreement Fee Income expense	$ (3,500)

[1]	Concurrently with the execution and delivery of the SPMA entered into between, Avenue, the Company and InvaGen Pharmaceuticals Inc. (“InvaGen”) (together, the “SPMA Parties”), the SPMA Parties entered into a waiver agreement (the “Waiver Agreement”), pursuant to which the Company irrevocably waived its right to receive the annual dividend of Avenue’s common shares under the terms of the Class A preferred stock and any fees, payments, reimbursements or other distributions under the management services agreement between the Company and Avenue and the Founders Agreement, for the period from the effective date of the Waiver Agreement to the termination of InvaGen’s rights under the SPMA. Pursuant to the Waiver Agreement, immediately prior to the closing of the Merger Transaction contemplated under the SPMA, the Company will convert all of its preferred shares into common shares pursuant to the terms of the certificate of incorporation of Avenue, as amended from time to time. (See Note 4).
[2]	Effective January 31, 2019 the Caelum Founders Agreement and MSA with Fortress were terminated in conjunction with the execution of a Development Option and Share Purchase Agreement (“DOSPA”) between Caelum and Alexion Therapeutics, Inc. (See Note 4).

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Millions		1 Months Ended	3 Months Ended
		Jan. 31, 2019	Mar. 31, 2019	Mar. 31, 2018
Related Party Transaction [Line Items]
Debt Instrument, Interest Rate, Stated Percentage			2.50%
Annual Management Services Agreement Fee Income Expense Written Off		$ 1
Opus Credit Facility [Member]
Related Party Transaction [Line Items]
Payments of Loan Costs			$ 0.3	$ 0.3
Debt Instrument, Interest Rate, Stated Percentage	[1]		12.00%
Chief Executive Officer [Member]
Related Party Transaction [Line Items]
Interest own in percent by principal stockholder or director			15.30%
TG Therapeutics, Inc [Member]
Related Party Transaction [Line Items]
Payments for Rent			$ 0.3
OPPM [Member]
Related Party Transaction [Line Items]
Due from Related Parties, Current			$ 0.1
Executives Vice Chairman [Member]
Related Party Transaction [Line Items]
Interest own in percent by principal stockholder or director			14.90%
Desk Share Agreements [Member]
Related Party Transaction [Line Items]
Payments for Rent			$ 0.7
Desk Share Agreements [Member] \| TG Therapeutics, Inc [Member]
Related Party Transaction [Line Items]
Due from Related Parties, Current			0.4
Desk Share Agreements [Member] \| OPPM [Member]
Related Party Transaction [Line Items]
Due from Related Parties, Current			0.4
Shared Services Agreement [Member] \| TG Therapeutics, Inc [Member]
Related Party Transaction [Line Items]
Proceeds from Related Party Agreement			0.1	$ 0.3
Due from Related Parties, Current			$ 0.1

[1]	Classified as short-term on the Company’s Consolidated Balance Sheet as of December 31, 2018.

Segment Information - Operating

Segment Information - Operating Results by Reportable Segment (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Segment Reporting Information [Line Items]
Net Revenue	$ 6,477	$ 5,903
Direct cost of goods	(1,884)	(1,472)
Research and development	(23,273)	(24,958)
General and administrative	(13,478)	(13,548)
Segment gain (loss) from operations	(32,608)	(34,172)
Segment assets	200,538		$ 140,993
Assets held for sale			13,089
Total consolidated	200,538		$ 140,993
Dermatology Products Sales [Member]
Segment Reporting Information [Line Items]
Net Revenue	6,125	5,509
Direct cost of goods	(1,884)	(1,472)
Sales and marketing costs	(3,493)	(2,764)
Research and development	0	0
General and administrative	(387)	(397)
Segment gain (loss) from operations	361	876
Segment assets	11,079	11,163
Total consolidated	11,079	11,163
Pharmaceutical and Biotechnology Product Development [Member]
Segment Reporting Information [Line Items]
Net Revenue	352	394
Direct cost of goods	0	0
Sales and marketing costs	0	0
Research and development	(23,723)	(25,055)
General and administrative	(9,598)	(10,387)
Segment gain (loss) from operations	(32,969)	(35,048)
Segment assets	189,459	189,560
Total consolidated	189,459	189,560
Consolidated [Member]
Segment Reporting Information [Line Items]
Net Revenue	6,477	5,903
Direct cost of goods	(1,884)	(1,472)
Sales and marketing costs	(3,493)	(2,764)
Research and development	(23,723)	(25,055)
General and administrative	(9,985)	(10,784)
Segment gain (loss) from operations	(32,608)	(34,172)
Segment assets	200,538	200,723
Assets held for sale	64,352
Total consolidated	$ 200,538	$ 200,723

Revenues from Contracts and S_3

Revenues from Contracts and Significant Customers - Company's product revenue (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Sales Revenue, Goods, Net	$ 6,125	$ 5,509
Total Revenue	6,477	5,903
Targadox [Member]
Sales Revenue, Goods, Net	5,700	5,498
Other Branded Revenue [Member]
Sales Revenue, Goods, Net	425	11
TGTX [Member]
Sales Revenue, Goods, Net	$ 352	$ 394

Revenues from Contracts and S_4

Revenues from Contracts and Significant Customers - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue from Contract with Customer, Including Assessed Tax	$ 6,125	$ 5,509
Customer One [Member]
Revenue from Contract with Customer, Including Assessed Tax	19,900	4,400
Accounts Receivable, Net	$ 7,700	3,000
Customer Two [Member]
Revenue from Contract with Customer, Including Assessed Tax		3,900
Accounts Receivable, Net		2,100
Customer Three [Member]
Revenue from Contract with Customer, Including Assessed Tax		$ 2,000

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	May 08, 2019	Apr. 30, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 29, 2019	Dec. 31, 2018
Subsequent Event [Line Items]
Common Stock, Shares, Issued				63,126,521		57,845,447
Common Stock, Par or Stated Value Per Share				$ 0.001		$ 0.001
Adjustments To Additional Paid In Capital At Market Offering Costs			$ (6)
Class of Warrant or Right, Exercise Price of Warrants or Rights					$ 3.47
Subsequent Event [Member] \| Mustang Bio, Inc [Member]
Subsequent Event [Line Items]
Common Stock Shares Available For Future Issuance Value	$ 20,900
Subsequent Event [Member] \| Market Offering [Member]
Subsequent Event [Line Items]
Proceeds from issuance of Common stock	$ 22,500
Common Stock, Shares, Issued	3,500,000
Common Stock, Par or Stated Value Per Share	$ 6.42
Adjustments To Additional Paid In Capital At Market Offering Costs	$ 400
Subsequent Event [Member] \| Over-Allotment Option [Member] \| Mustang Bio, Inc [Member]
Subsequent Event [Line Items]
Stock Issued During Period, Value, New Issues		$ 31,600
Stock Issued During Period, Shares, New Issues		6,875,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		1,031,250
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 4

Sponsored Research and Clinical Trial Agreements	3 Months Ended
Sponsored Research and Clinical Trial Agreements	Mar. 31, 2019
Research and Development [Abstract]
Sponsored Research and Clinical Trial Agreements	8. Sponsored Research and Clinical Trial Agreements Aevitas In 2018, Aevitas entered into a Sponsored Research Agreement (SRA) with the University of Massachusetts (“UMass SRA”) for certain continued research and development activities related to the development of adeno-associated virus (“AAV”) gene therapies in complement-mediated diseases and with the Trustees of the University of Pennsylvania (“UPenn SRA”) for certain continued research and development activities related to the development of AAV gene therapies in complement-mediated diseases. For the three months ended March 31, 2019 and 2018, Aevitas recorded the following expense in research and development for sponsored research and clinical trial agreements: For the Three Months Ended March 31, ($ in thousands) 2019 2018 UMass – AAV $ – $ 100 UPenn – AAV 250 – Total $ 250 $ 100 Cellvation For the three months ended March 31, 2019 and 2018, respectively, Cellvation recorded expense of $0.1 million and $0.1 million, respectively, in connection with its sponsored research arrangement with the University of Texas. The expense was recorded in research and development expense in the Company’s condensed consolidated statements of operations. Mustang For the three months ended March 31, 2019 and 2018, Mustang recorded the following expense in research and development for sponsored research and clinical trial agreements: For the Three Months Ended March 31, ($ in thousands) 2019 2018 City of Hope (COH) $ 500 $ 500 COH – CD123 (MB-102) 303 150 COH – IL13R a 342 360 COH – manufacturing 114 114 Fred Hutch-CD20 (MB-106) 267 266 BIDMC – CRISPR 69 – Total $ 1,595 $ 1,390

Sponsored Research and Clinical Trial Agreements (Tables)	3 Months Ended
Sponsored Research and Clinical Trial Agreements (Tables)	Mar. 31, 2019
Aevitas Therapeutics Inc [Member]
Schedule Of Expense Related To Sponsered Research Arrangements	For the three months ended March 31, 2019 and 2018, Aevitas recorded the following expense in research and development for sponsored research and clinical trial agreements: For the Three Months Ended March 31, ($ in thousands) 2019 2018 UMass – AAV $ – $ 100 UPenn – AAV 250 – Total $ 250 $ 100
Mustang Therapeutics, Inc [Member]
Schedule Of Expense Related To Sponsered Research Arrangements	For the three months ended March 31, 2019 and 2018, Mustang recorded the following expense in research and development for sponsored research and clinical trial agreements: For the Three Months Ended March 31, ($ in thousands) 2019 2018 City of Hope (COH) $ 500 $ 500 COH – CD123 (MB-102) 303 150 COH – IL13R a 342 360 COH – manufacturing 114 114 Fred Hutch-CD20 (MB-106) 267 266 BIDMC – CRISPR 69 – Total $ 1,595 $ 1,390

Fortress Biotech (FBIO) 10-Q10 May 192019 Q1 Quarterly reportFinancial data

Document and Entity Information

Consolidated Balance Sheets

Consolidated Balance Sheets (Pa

Consolidated Statements of Oper

Condensed Consolidated Statemen

Consolidated Statements of Cash

Organization and Description of

Summary of Significant Accounti

Discontinued Operations

Collaboration and Stock Purchas

Property and Equipment

Fair Value Measurements

Licenses Acquired

Sponsored Research and Clinical

Intangibles, net

Debt and Interest

Leases

Accrued Liabilities and other L

Non-Controlling Interests

Net Income (Loss) per Common Sh

Stockholders' Equity

Commitments and Contingencies

Related Party Transactions

Segment Information

Revenues from Contracts and Sig

Incomes taxes

Subsequent Events

Summary of Significant Accoun_2

Discontinued Operations (Tables

Collaboration and Stock Purch_2

Property and Equipment (Tables)

Fair Value Measurements (Tables

Licenses Acquired (Tables)

Sponsored Research and Clinic_2

Intangibles, net (Tables)

Debt and Interest (Tables)

Leases (Tables)

Accrued Liabilities and other_2

Non-Controlling Interests (Tabl

Net Income (Loss) per Common _2

Stockholders' Equity (Tables)

Related Party Transactions (Tab

Segment Information (Tables)

Revenues from Contracts and S_2

Summary of Significant Accoun_3

Discontinued Operations- Summar

Discontinued Operations- Classi

Discontinued Operations- Cash f

Discontinued Operations- Additi

Collaboration and Stock Purch_3

Collaboration and Stock Purch_4

Collaboration and Stock Purch_5

Property and Equipment - Compon

Property and Equipment - Additi

Fair Value Measurements - Conti

Fair Value Measurements - Deriv

Fair Value Measurements - Warra

Fair Value Measurements - Exclu

Fair Value Measurements - Chang

Fair Value Measurements - Cha_2

Fair Value Measurements - Addit

Licenses Acquired - Summary Of

Licenses Acquired - license as

Licenses Acquired - Additional

Sponsored Research and Clinic_3

Sponsored Research and Clinic_4

Sponsored Research and Clinic_5

Intangibles, net - Summary Of T

Intangibles, net - Cost Of Good

Intangibles, net - Amortization

Debt and Interest - Long-term d

Debt and Interest - Schedule of

Debt and Interest- Additional I

Leases - summarizes quantitativ

Leases - lease expense (Detail)

Leases - future minimum lease p

Leases - Additional Information

Accrued Liabilities and other_3

Non-Controlling Interests - Sum