Company: MBIO
Filing Date: 2025-04-01
Form Type: 424B3
Source: 0001104659-25-030657
Chunk: 138

Company: MUSTANG BIO, INC.
Filing Date: 2025-04-01
Form: 424B3
Chunk 138
---
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, and costs associated with regulatory filings, laboratory costs and other supplies.

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 commercial feasibility and has no alternative future use. In each case, we evaluate if the license agreement
results in the acquisition of an asset or a business. Such licenses purchased by us require substantial completion of research and development,
regulatory and marketing approval efforts in order to reach commercial feasibility and have no alternative future use. Accordingly, the
total purchase price for the licenses acquired during the period was reflected as research and development - licenses acquired on the
Statements of Operations for the years ended December 31, 2024, and 2023.

<div align='center'>69</div>

​

Table of Contents

Accrued Research and Development Expense

We record accruals for estimated costs of research,
preclinical, clinical and manufacturing development within accrued expenses which are significant components of research and development
expenses. A substantial portion of our ongoing research and development activities is conducted by third-party service providers. We accrue
the costs incurred under agreements with these third parties based on estimates of actual work completed in accordance with the respective
agreements. We determine the estimated costs through discussions with internal personnel and external service providers as to the progress,
or stage of completion or actual timeline (start-date and end-date) of the services and the agreed-upon fees to be paid for such services.
Payments made to third parties under these arrangements in advance of the performance of the related services are recorded as prepaid
expenses until the services are rendered.

If the actual timing of the performance of services
or the level of effort varies from the estimate, we adjust accrued expenses or prepaid expenses accordingly, which impact research and
development expenses. Although we do not expect our estimates to be materially different from amounts actually incurred, our understanding
of the status and timing of services performed relative to the actual status and timing of services performed may vary and may result
in reporting amounts that are too high or too low in any particular period.

Recent Accounting