Mustang Bio Announces Favorable Efficacy and Safety Data from Complete Waldenstrom Macroglobulinemia Cohort of Phase 1/2 Clinical Trial of MB-106, CD20-Targeted Autologous CAR-T Therapy

Overall response rate of 90% in cohort with durable responses observed; one patient remains in complete remission at 31 months

All patients were heavily pretreated/refractory to BTK inhibitors, and only one patient has started new anti-WM treatment after MB-106

Outpatient administration was allowed and found to be feasible

Currently no FDA-approved CAR-T treatments for WM

Data presented at the European Hematology Association 2024 Hybrid Congress

WORCESTER, Mass., June 17, 2024 (GLOBE NEWSWIRE) — Mustang Bio, Inc. (“Mustang” or the “Company”) (Nasdaq: MBIO), a clinical-stage biopharmaceutical company focused on translating today’s medical breakthroughs in cell therapies into potential cures for difficult-to-treat cancers, today announced that updated data from the ongoing Phase 1/2 clinical trial of MB-106, a CD20-targeted, autologous CAR T-cell therapy, show a favorable safety and efficacy profile in patients with Waldenstrom macroglobulinemia (“WM”), a rare form of blood cancer. MB-106 is being developed in a collaboration between Mustang and Fred Hutch Cancer Center (“Fred Hutch”) to treat patients with relapsed or refractory B-cell non-Hodgkin lymphomas (“B-NHLs”) and chronic lymphocytic leukemia (“CLL”).

The updated results from the single-institution Phase 1/2 clinical trial were presented during a poster session at the European Hematology Association 2024 Hybrid Congress (“EHA2024”) by Brian Till, M.D., Associate Professor and physician at Fred Hutch and University of Washington.

All ten patients in the study were previously treated with Bruton’s tyrosine kinase inhibitors (“BTKi”), and their disease continued to progress while on BTKi. Overall, 90% (9/10) of the patients treated with MB-106 responded to treatment, including 3 complete responses, 2 very good partial responses and 4 partial responses. In addition, 1 patient experienced stable disease. One of the patients who achieved a complete response has remained in remission for 31 months, with an immunoglobulin M (IgM) level that decreased rapidly to the normal range after treatment with MB-106 and has remained normal since. Patients had a median of nine prior lines of therapy and only one patient has started additional anti-WM treatment after being treated with MB-106. From a safety perspective, cytokine release syndrome (CRS) occurred in nine patients: five patients with grade 1 and four patients with grade 2. One patient experienced grade 1 immune effector cell-associated neurotoxicity syndrome (ICANS). No grade 3 or 4 CRS or grade 2, 3 or 4 ICANS has been observed, despite dose escalation.

“We are very encouraged by the safety and efficacy data generated in WM, along with improvements in the quality of responses over time, which demonstrates MB-106 CAR T-cell expansion and persistence,” said Dr. Till.

For more information on the clinical trials, please visit www.clinicaltrials.gov using the identifier NCT05360238 for the multicenter trial and NCT03277729 for the ongoing trial at Fred Hutch.

Scientists at Fred Hutch played a role in developing these discoveries, and Fred Hutch and its scientists may benefit financially from this work in the future.

The Company’s ability to further develop the MB-106 program for hematologic malignancies is contingent upon raising a significant amount of additional funding and / or consummating a strategic partnership.

About Mustang Bio
Mustang Bio, Inc. is a clinical-stage biopharmaceutical company focused on translating today’s medical breakthroughs in cell therapies into potential cures for difficult-to-treat cancers. Mustang aims to acquire rights to these technologies by licensing or otherwise acquiring an ownership interest, to fund research and development, and to outlicense or bring the technologies to market. Mustang has partnered with top medical institutions to advance the development of CAR-T therapies. Mustang’s common stock is registered under the Securities Exchange Act of 1934, as amended, and Mustang files periodic reports with the U.S. Securities and Exchange Commission (“SEC”). Mustang was founded by Fortress Biotech, Inc. (Nasdaq: FBIO). For more information, visit www.mustangbio.com.

Forward-Looking Statements
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Company Contacts:
Jaclyn Jaffe and Nicole McCloskey
Mustang Bio, Inc.
(781) 652-4500
ir@mustangbio.com