Company: MBIO
Filing Date: 2025-04-01
Form Type: 424B3
Source: 0001104659-25-030657
Chunk: 140

Company: MUSTANG BIO, INC.
Filing Date: 2025-04-01
Form: 424B3
Chunk 140
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, benefits, travel, and other related expenses, stock-based compensation, payments made
to third parties for license, sponsored research and milestone costs related to in-licensed

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Table of Contents

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 manufacturing clinical trial materials, costs associated with regulatory filings and laboratory service costs.

Research and development expenses decreased by
approximately $32.9 million from $40.5 million for the year ended December 31, 2023, to $7.6 million for the year ended December 31, 2024.
The decrease in research and development expense for the year ended December 31, 2024, was primarily attributable to the following:

| ● | $13.9 million decrease in research and development employee compensation costs, including stock compensation, primarily reflecting the reduction in the workforce that occurred in April 2024; |

| ● | $8.2 million decrease in laboratory supply costs, including vector manufacturing costs, primarily due to stopping manufacturing activity due to the termination of the MB-106 clinical trial; |

| ● | $6.1 million decrease in program related costs, which primarily reflects the termination of certain licenses and closing the MB-106 clinical trial; |

| ● | $2.9 million decrease in consulting expenses, primarily reflecting the reduced support needed as a result of closing the MB-106 clinical trial; and |

| ● | $1.8 million decrease in other expenses, including depreciation and rent expense. |

Research and development expenses - licenses
acquired increased by $0.4 million from $0.5 million for the year ended December 31, 2023, to $0.9 million for the year
ended December 31, 2024. The increase in research and development expenses - licenses acquired for the year ended December 31, 2024,
reflects approximately $0.1 million increase for the annual stock dividend to Fortress, and $0.3 million increase in clinical development
milestones achieved related to our license with Nationwide Children’s.

The following table provides a breakout of the
components of research and development expenses for the years ended December 31, 2024 and 2023:

| ​                                      
 ​                                      | ​                
 ​                
 ($ in thousands) | ​                               
 For the year ended December 31, 
 ​                               |      ​ 
   202