MUSTANG BIO, INC.

FOURTH AMENDMENT TO THE MUSTANG BIO, INC.

2016 INCENTIVE PLAN

This Fourth Amendment to the Mustang Bio, Inc. 2016 Incentive Plan (the “Plan”), is hereby adopted on this __ day of December, 2025, by the Board of Directors (the “Board”) of Mustang Bio, Inc. (the “Company”).

WITNESETH:

WHEREAS, the Company adopted the Plan for the purposes set forth therein; and

WHEREAS, pursuant to Section 15.1 of the Plan, the Board has the right to amend the Plan with respect to certain matters, provided that any material increase in the number of Shares available under the Plan shall be subject to stockholder approval; and

WHEREAS, the Board has approved and authorized this Fourth Amendment to the Plan and has recommended that the stockholders of the Company approve this Fourth Amendment;

NOW, THEREFORE, BE IT RESOLVED, that the Plan is hereby amended, subject to and effective as of thedate of stockholder approval hereof, in the following particulars:

“5.1. NUMBER OF SHARES. Subject to adjustment as provided in Sections 5.2 and Section 14.1, the aggregate number of Shares reserved and available for issuance pursuant to Awards granted under the Plan shall be 2,514,666. The maximum number of Shares that may be issued upon exerciseof Incentive Stock Options granted under the Plan shall be 2,514,666. The maximum aggregate number of Shares associated with any Award granted under the Plan in any calendar year to any one Non-Employee Director shall be 100,000 Shares.”

The foregoing is hereby acknowledged as being the Fourth Amendment to the Plan, as adopted by the Board on November 17, 2025, and approved by the Company’s stockholders on December, 2025.

By:​ ​

Name: Manuel Litchman, M.D.

Title: President, Chief Executive Officer and Interim Chief Financial Officer

Signature [PLEASE SIGN WITHIN BOX] Date Signature (Joint Owners) Date TO VOTE, MARK BLOCKS BELOW IN BLUE OR BLACK INK AS FOLLOWS: KEEP THIS PORTION FOR YOUR RECORDS DETACH AND RETURN THIS PORTION ONLY THIS PROXY CARD IS VALID ONLY WHEN SIGNED AND DATED. V81572-P40333 01) Michael S. Weiss 02) Adam J. Chill 03) Neil Herskowitz 04) David Jin 05) Manuel Litchman, M.D. 06) Lindsay A. Rosenwald, M.D. 07) Michael J. Zelefsky, M.D. For All Withhold All For All Except For Against Abstain For Against Abstain ! ! ! MUSTANG BIO, INC. Nominees: 2. Ratify the appointment of KPMG LLP as the Company's independent registered public accounting firm for the year ending December 31, 2025. 3. Approve an amendment to the Company's 2019 Employee Stock Purchase Plan, as amended, to increase the number of shares issuable thereunder by 250,000 shares, from 9,333 to 259,333, and increase the number of shares of Common Stock subject to a Purchase Right thereunder to 10,000. 4. Approve an amendment to the Company's 2016 Incentive Plan, as amended, to increase the number of shares issuable by the Company by 2,500,000 shares, from 14,666 to 2,514,666. NOTE: In their discretion, the proxies are authorized to vote upon such other business as may properly come before the Annual Meeting or any adjournment or postponement thereof. This proxy, when properly executed, will be voted as directed herein by the undersigned stockholder. If no direction is made, the proxy will be voted in accordance with the Board of Directors’ recommendations and, accordingly, will be voted FOR each of the Board of Directors’ nominees for director specified in proposal 1 and FOR proposals 2, 3 and 4. 1. Election of Directors The Board of Directors recommends you vote FOR the following: The Board of Directors recommends you vote FOR the following proposal: The Board of Directors recommends you vote FOR the following proposal: ! ! ! To withhold authority to vote for any individual nominee(s), mark "For All Except" and write the number(s) of the nominee(s) on the line below. Please sign exactly as your name(s) appear(s) hereon. When signing as attorney, executor, administrator, or other fiduciary, please give full title as such. Joint owners should each sign personally. All holders must sign. If a corporation or partnership, please sign in full corporate or partnership name by authorized officer. The Board of Directors recommends you vote FOR the following proposal: For Against Abstain ! ! ! ! ! ! SCAN TO VIEW MATERIALS & VOTEw MUSTANG BIO, INC. 95 SAWYER ROAD, SUITE 110 WALTHAM, MA 02453 VOTE BY INTERNET Before The Meeting - Go to www.proxyvote.com or scan the QR Barcode above Use the Internet to transmit your voting instructions and for electronic delivery of information. Vote by 11:59 P.M. ET on December 21, 2025. Have your proxy card in hand when you access the web site and follow the instructions to obtain your records and to create an electronic voting instruction form. During The Meeting - Go to www.virtualshareholdermeeting.com/MBIO2025 You may attend the meeting via the Internet and vote during the meeting. Have the information that is printed in the box marked by the arrow available and follow the instructions. VOTE BY PHONE - 1-800-690-6903 Use any touch-tone telephone to transmit your voting instructions. Vote by 11:59 P.M. ET on December 21, 2025. Have your proxy card in hand when you call and then follow the instructions. VOTE BY MAIL Mark, sign and date your proxy card and return it in the postage-paid envelope we have provided or return it to Vote Processing, c/o Broadridge, 51 Mercedes Way, Edgewood, NY 11717.

V81573-P40333 Important Notice Regarding the Availability of Proxy Materials for the Annual Meeting: The Notice and Proxy Statement and Annual Report are available at www.proxyvote.com. Continued and to be signed on reverse side MUSTANG BIO, INC. Annual Meeting of Stockholders December 22, 2025 9:00 AM, EST This proxy is solicited by the Board of Directors The stockholder(s) hereby appoint(s) Manuel Litchman, M.D. and Peter Carney, or either of them as proxies, each with the power to appoint his substitute, and hereby authorize(s) them to represent and to vote, as designated on the reverse side of this ballot, all of the shares of (Common/Preferred) Stock of MUSTANG BIO, INC. that the stockholder(s) is/are entitled to vote at the Annual Meeting of Stockholders to be held at 9:00 AM, EST on Monday, December 22, 2025, virtually at www.virtualshareholdermeeting.com/MBIO2025, and any adjournment or postponement thereof. This proxy, when properly executed, will be voted in the manner directed herein. If no such direction is made, this proxy will be voted in accordance with the Board of Directors' recommendations.