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Significant Accounting Policies | 12 Months Ended
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Dec. 31, 2024
Significant Accounting Policies |
Significant Accounting Policies | Note 2 - Significant Accounting Policies Basis of Presentation The Company’s financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”). The Company has no subsidiaries. All inter-company transactions between Fortress and Mustang are classified as due from or due to related party in the financial statements. Segment Reporting Operating segments are defined as components of an enterprise about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources in assessing performance. The Company views its operations and manages its business in one segment, which reflects the research and development of potential cures for difficult-to-treat cancers and autoimmune diseases. The Company’s chief operating decision maker (“CODM”) is its chief executive officer. The CODM assesses performance for the research and development segment and decides how to allocate resources based on net loss, which is reported on the Statements of Operations. The CODM uses net loss to evaluate costs to develop its pipeline. The accounting policies of the segment are the same as those described in this Note 2. See Note 12 for segment information. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates. Cash and Cash Equivalents The Company considers highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Cash and cash equivalents at December 31, 2024 and 2023, consisted of cash and certificates of deposit in institutions in the United States. The Company maintains its cash and cash equivalent balances with high-quality financial institutions and, consequently, the Company believes that such funds are currently adequately protected against credit risk. At times, portions of the Company’s cash and cash equivalents may be uninsured or in deposit accounts that exceed Federal Deposit Insurance Corporation (FDIC) limits, though the Company customarily invests a significant portion of its cash in Insured Cash Sweep (“ICS”) accounts to maximize FDIC insurance coverage across its holdings. As of December 31, 2024, the Company had not experienced losses on these accounts, and management believes the Company is not exposed to significant risk on such accounts. Other Receivables – Related Party Other receivables include amounts due to the Company from Fortress and is recorded at the invoiced amount. Restricted Cash The Company records cash held in an escrow account as a security deposit for the manufacturing facility in Worcester, Massachusetts, as restricted cash. The Company had no restricted cash as of December 31, 2024, and $0.8 million in restricted cash as of December 31, 2023. Property, plant and equipment, net Property, plant and equipment, net, consists primarily of leasehold improvements, are carried at cost less accumulated depreciation. Depreciation for leasehold improvements is computed over the shorter of the estimated useful lives or the term of the respective leases. Depreciation for all other property and equipment assets is recorded over the useful lives of the respective assets, generally five years, using the straight-line method. Property, plant and equipment, held for sale Property, plant and equipment, held for sale represent assets that have met the criteria of “held for sale” accounting, as specified by Accounting Standards Codification (“ASC”) 360, “Long-lived Assets.” As of December 31, 2024, there were $1.2 million of lab and cell processing equipment, furniture and fixtures and computer equipment that are recorded as assets held for sale. The effect of suspending depreciation on the assets held for sale is immaterial to the results of operations. The assets held for sale were part of the repurchase of assets from uBriGene (see Note 5). ​ Impairment of Long-Lived Assets ​ The Company reviews long-lived assets, including tangible assets and other intangible assets with definitive lives, for impairment whenever events or changes in circumstances indicate that the asset’s carrying amount may not be recoverable. The Company conducts its long-lived asset impairment analyses in accordance with ASC 360-10, "Impairment or Disposal of Long-Lived Assets. ASC 360-10-15 requires the Company to group assets and liabilities at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities and evaluate the asset group against the sum of the undiscounted future cash flows. If the undiscounted cash flows do not indicate the carrying amount of the asset group is recoverable, an impairment charge is measured as the amount by which the carrying amount of the asset group exceeds its fair value based on discounted cash flow analysis or appraisals. ​ Research and Development Costs Research and development costs are expensed as incurred. Advance payments for goods and services that will be used in future research and development activities are expensed when the activity has been performed or when the goods have been received rather than when the payment is made. Upfront and milestone payments due to third parties that perform research and development services on the Company’s behalf will be expensed as services are rendered or when the milestone is achieved. Research and development costs primarily consist of personnel related expenses, including salaries, benefits, travel, and other related expenses, stock-based compensation, payments made to third parties for license and milestone costs related to in-licensed products and technology, payments made to third party contract research organizations for preclinical and clinical studies, investigative sites for clinical trials, consultants, the cost of acquiring and manufacturing clinical trial materials, costs associated with regulatory filings, laboratory costs and other supplies. In accordance with Accounting Standards Codification (“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 commercial feasibility and has no alternative future use. The licenses purchased by the Company require substantial completion of research and development, regulatory and marketing approval efforts to reach commercial feasibility and has no alternative future use. Accordingly, the total purchase price for the licenses acquired is reflected as research and development – licenses acquired in the Company’s Statements of Operations. Annual Stock Dividend to Fortress In July 2016, in connection with the Amended and Restated Articles of Incorporation, the Company issued 250,000 Class A preferred shares to Fortress. The Class A preferred shares entitle the holder to a stock dividend equal to 2.5% of the fully diluted outstanding equity of the Company (the “Annual Stock Dividend”). The Annual Stock Dividend was part of the consideration payable for formation of the Company and the identification of certain assets, including the license contributed to Mustang by Fortress (see Note 4). The Company considers the Annual Stock Dividend as contingent consideration for the license contributed to Mustang by Fortress. Since the ultimate amount of the Annual Stock Dividend is highly uncertain and cannot be reasonable estimable, in accordance with ASC 450-20, Loss Contingencies, the Company records the Annual Stock Dividend in Research and development expense – licenses acquired in the Company’s Statements of Operations, when the shares are issued. Fair Value Measurement The Company follows accounting guidance on fair value measurements for financial assets and liabilities measured at fair value on a recurring basis. Under the accounting guidance, fair value is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. The accounting guidance requires fair value measurements be classified and disclosed in one of the following three categories: ​ Level 1: Quoted prices in active markets for identical assets or liabilities. Level 2: Observable inputs other than Level 1 prices, for similar assets or liabilities that are directly or indirectly observable in the marketplace. Level 3: Unobservable inputs which are supported by little or no market activity and that are financial instruments whose values are determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant judgment or estimation. ​ The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. Leases Arrangements meeting the definition of a lease are classified as operating or financing leases and are recorded on the 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. 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 excludes short-term leases having initial terms of 12 months or less from the new guidance as an accounting policy election and recognizes rent expense on a straight-line basis over the lease term. 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. The Company estimates the fair value of stock option grants using the Black-Scholes option pricing model. 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. Income Taxes The Company records income taxes using the asset and liability method. Deferred income tax assets and liabilities are recognized for the future tax effects attributable to temporary differences between the financial statement carrying amounts of existing assets and liabilities and their respective income tax bases, and operating loss and tax credit carryforwards. The Company establishes a valuation allowance if management believes it is more likely than not that the deferred tax assets will not be recovered based on an evaluation of objective verifiable evidence. For tax positions that are more likely than not of being sustained upon audit, the Company recognizes the largest amount of the benefit that is greater than 50% likely of being realized. For tax positions that are not more likely than not of being sustained upon audit, the Company does not recognize any portion of the benefit. Net Loss per Share Basic and diluted net loss per share is computed by dividing net loss by the weighted average number of common shares outstanding, including prefunded warrants and shares held in abeyance, during the period, without consideration of potential dilutive securities. For periods in which the Company generated a net loss, the Company does not include potential shares of common stock in diluted net loss per share when the impact of these items is anti-dilutive. The Company has generated a net loss for all periods presented, therefore diluted net loss per share is the same as basic net loss per share since the inclusion of potentially dilutive securities would be anti-dilutive. ​ The table below summarizes potentially dilutive securities that were not considered in the computation of diluted net loss per share because they would be anti-dilutive. ​
​ | ​ | ​ | ​ | ​
​ | ​ | For the year ended December 31,
​ |  | 2024 |  | 2023
Warrants |  | 1,576,919 | ​ | 56,254
Options |  | 1,521 |  | 1,521
Class A preferred shares (1) |  | 333 |  | 333
Unvested restricted stock awards |  | 1,195 |  | 1,285
Unvested restricted stock units |  | 226 |  | 1,911
Total |  | 1,580,194 |  | 61,304
​
(1) | Class A Preferred Shares are reflected on an as-if converted basis.
In connection with the exercise of certain existing warrants in October 2024 (see Note 10), the Company recorded a deemed dividend of approximately $7.8 million for the issuance of new warrants. For the year ended December 31, 2024, net loss attributable to common stockholders consisted of net loss, as adjusted for deemed dividends. ​ The Company considers Class A common stock and Class A preferred stock to be additional classes of common stock for the purpose of calculating net loss per share, as they do not have preferential rights when compared to the Company’s common stock, and therefore losses are allocated to these additional classes using the two-class method. The two-class method is an earnings allocation formula that treats participating securities as having rights that would otherwise have been available to common stockholders. At December 31, 2024, the Class A common stock and Class A preferred stock have rights to convert to a total of 1,461 common shares. ​ Comprehensive Loss The Company has no components of other comprehensive loss, and therefore, comprehensive loss equals net loss. Recent Accounting Pronouncements In November 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2023-07, “Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures.” The amendments in ASU 2023-07 improve reportable segment disclosure requirements through enhanced disclosures about significant segment expenses. The amendments introduce a new requirement to disclose significant segment expenses regularly provided to the chief operating decision maker (“CODM”), extend certain annual disclosures to interim periods, clarify single reportable segment entities must apply ASC 280 in its entirety, permit more than one measure of segment profit or loss to be reported under certain conditions, and require disclosure of the title and position of the CODM. This guidance is effective for fiscal years, beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024. Early adoption will be permitted. The Company adopted the ASU on its annual report on Form 10-K for the year ended December 31, 2024. ​ In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which expands disclosures in an entity’s income tax rate reconciliation table and disclosures regarding cash taxes paid both in the U.S. and foreign jurisdictions. The update will be effective for annual periods beginning after December 15, 2024. The Company is currently evaluating the impact that this guidance will have on our financial statements and disclosures. ​ In November 2024, the FASB issued ASU 2024-03, Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Topic 220-40). The amendments in this update require new disclosures to disaggregate prescribed natural expenses underlying any income statement caption. ASU 2024-03 is effective for annual periods in fiscal years beginning after December 15, 2026, and interim periods thereafter. Early adoption is permitted. ASU 2024-03 applies on a prospective basis for periods beginning after the effective date. However, retrospective application to any or all prior periods presented is permitted. The Company is currently assessing the impact ASU 2024-03 will have on the financial statements and disclosures.

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