Mustang Bio Announces Final Results from Follicular Lymphoma Cohort of Single-Institution Phase 1/2 Clinical Trial of MB-106, CD20-Targeted Autologous CAR T Therapy

On June 15, 2023 Mustang Bio, Inc. ("Mustang" or the "Company") (Nasdaq: MBIO), a clinical-stage biopharmaceutical company focused on translating today’s medical breakthroughs in cell and gene therapies into potential cures for difficult-to-treat cancers and rare genetic diseases, reported that final data from the follicular lymphoma ("FL") cohort of the single-institution Phase 1/2 clinical trial of MB-106 demonstrate treatment with the CD20-targeted, autologous CAR T-cell therapy resulted in high overall response ("ORR") and complete response ("CR") rates and CAR T persistence in FL patients (Press release, Mustang Bio, JUN 15, 2023, View Source [SID1234632733]). MB-106 is being developed in a collaboration between Mustang and Fred Hutchinson Cancer Center ("Fred Hutch") to treat patients with relapsed or refractory B-cell non-Hodgkin lymphomas ("B-NHLs") and chronic lymphocytic leukemia ("CLL").

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The final FL cohort results from the Phase 1/2 clinical trial being conducted at Fred Hutch were presented by Mazyar Shadman, M.D., M.P.H., Associate Professor and physician at Fred Hutch and University of Washington, at the 17th International Conference on Malignant Lymphoma ("17-ICML").

"MB-106 continues to show promise as a viable treatment option for patients with FL and other B-NHLs, as evidenced by a 95% overall response rate in the FL cohort of the Phase 1/2 clinical trial, including a patient previously treated with a CD19 CAR T-cell therapy who remains in remission," said Dr. Shadman. "Importantly, MB-106 was infused in an outpatient setting except for the first patient at each dose level, further highlighting the potential of this therapy to fill an unmet need in FL and other B-NHLs. We look forward to the publication of the final data in a peer-reviewed journal in the near future."

A total of 20 patients with relapsed FL with confirmed CD20 expression participated in the study and had day 28 assessment. Median age was 63 years (range: 44 – 81), and median prior lines of treatment was 4 (range: 1 – 12). High-risk features included patients with progression of disease within 24 months of first-line chemoimmunotherapy (POD24) (n=15; 75%), history of histologic transformation (n=4, 20%), prior treatment with a CD19 target CAR T (n=1, 5%). ORR was 95% (19/20), and CR rate was 80% (16/20). Patients who received higher dose levels (3.3 x 106 and 1.0 x 107 cells/kg) had an ORR of 100% and a CR rate of 91%. Ten patients are in remission over one year, seven of whom are over two years. One patient, previously treated with a CD19-targeted CAR T-cell therapy, achieved a CR and remains in remission after 18 months. From a safety profile perspective, all cytokine release syndrome ("CRS") events were grade 1 (n=5; 25%) or grade 2 (n=1; 5%), with no grade ≥ 3 CRS events. There was no occurrence of immune effector cell-associated neurotoxicity syndrome of any grade.

Manuel Litchman, M.D., President and Chief Executive Officer of Mustang, commented, "We are encouraged by the MB-106 data from the FL cohort presented by Dr. Shadman at 17-ICML from the Fred Hutch Phase 1/2 clinical trial, as well as the data from the Waldenstrom macroglobulinemia cohort that he recently presented at the European Hematology Association (EHA) (Free EHA Whitepaper) 2023 Hybrid Congress. The data underscore the great potential of MB-106 to treat a range of hematologic malignancies. We look forward to reporting initial data from our multicenter Phase 1/2 clinical trial of MB-106 shortly."

For more information on the multicenter clinical trial, please visit www.clinicaltrials.gov using the identifier NCT05360238 for the multicenter trial.

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

About MB-106 (CD20-targeted autologous CAR T-Cell Therapy)
CD20 is a membrane-embedded surface molecule which plays a role in the differentiation of B-cells into plasma cells. The CAR T was developed by Mustang’s research collaborator, Fred Hutch, in the laboratories of the late Oliver Press, M.D., Ph.D., and Brian Till, M.D., Associate Professor in the Clinical Research Division at Fred Hutch, and was exclusively licensed to Mustang in 2017. The lentiviral vector drug substance used to transduce patients’ cells to create the MB-106 drug product produced at Fred Hutch has been optimized as a third-generation CAR derived from a fully human antibody, and MB-106 is currently in a Phase 1/2 open-label, dose-escalation trial at Fred Hutch in patients with B-NHLs and CLL. The same lentiviral vector drug substance produced at Fred Hutch will be used to transduce patients’ cells to create the MB-106 drug product produced at Mustang Bio’s Worcester, MA, cell processing facility for administration in the planned multicenter Phase 1/2 clinical trial that is now open to enrollment under Mustang Bio’s IND. It should be noted that Mustang Bio has introduced minor improvements to its cell processing to facilitate eventual commercial launch of the product. In addition, prior to commercial launch, Mustang Bio will replace the Fred Hutch lentiviral vector drug substance with vector produced at a commercial manufacturer. Additional information on the trials can be found at View Source using the identifier NCT05360238 for the multicenter trial and NCT03277729 for the ongoing trial at Fred Hutch. Mustang Bio has entered into an Asset Purchase Agreement pursuant to which it has agreed to sell, subject to the satisfaction of certain conditions, its leasehold interest in its cell processing facility and expects to enter into a manufacturing services agreement with the prospective purchaser to provide for the continued production of the MB-106 drug product. For additional information, please refer to the Current Report on Form 8-K filed by Mustang Bio with the U.S. Securities and Exchange Commission ("SEC") on May 22, 2023.