Dystrophin Expressing Chimeric Cell Therapy Demonstrates Long-Term Safety in Non-Ambulatory Duchenne Muscular Dystrophy

Maria Siemionow, MD, PhD, DSc

Findings from a pilot single-site, open-label study showed that DT-DEC01 (Dystrogen Therapeutics), an investigational dystrophin expressing chimeric (DEC) cell therapy, was safe in non-ambulatory patients with Duchenne muscular dystrophy (DMD) for a 24-month period. Coupled with improvements on functional tests, the findings further support the development of the agent as a treatment for DMD, regardless of gene mutation or disease progression.¹

Led by Maria Siemionow, MD, PhD, DSc, professor and director of Microsurgery Research at the University of Illinois, the analysis featured 24-month data on 3 patients, aged 11-16, who received doses of 2x10⁶, 4x10⁶, and 6x10⁶ cells per kg body weight, respectively, without immunosuppression. Presented at the 2025 Muscular Dystrophy Association (MDA) Clinical & Scientific conference, held March 16-19, in Dallas, Texas, treatment with the cell therapy results in zero study-related adverse events (AEs), serious AEs, or donor-specific antibodies (DSA) up to 24 months.

The affected patients received DT-DEC01 via intraosseous administration to the bone marrow compartment of the patient’s iliac crest. Conducted under anesthesia, patients first underwent bone marrow aspiration to create space before receiving their injection, which lasted on average 7 minutes. Following administration, patients were hospitalized for 24 h and closely monitored for any potential responses associated with the procedure.

Patient 1, a 15-year-old with exon 48-50 deletion, showed improvements in echocardiography EF by 12%, arm movements by 9%, and Motor Unit Potentials (MUP) duration, both in deltoideus (53%) and biceps brachii (23%) at 18 months. In addition, this patient saw enhancements in PUL 2.0 test score by 5%, grip strength by 6%, and spirometry by 17% after 24 months since the original procedure.

Patient 2, an 11-year-old with exon 52 deletion, demonstrated a 17% improvement in echocardiography EF at 12 months, along with a 5% increase in PUL 2.0 test score and enhancements in MUP duration, including 19% in the deltoideus and 51% in the biceps brachii, at 18 months. Furthermore, this patient experienced a 59% improvement in spirometry and a remarkable 1150% increase in arm movements at 24 months.

Patient 3, a 16-year-old with a nonsense mutation, reported improvements at 12 months post-DT-DEC01 administration, including a 6% increase in PUL 2.0 test score, a 34% improvement in grip strength, an 11% enhancement in echocardiography EF, and increases in MUP duration, with 49% in the deltoideus and 29% in the biceps brachii.

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Developed by Dystrogen Therapeutics, DT-DEC01 involves fusing allogeneic human myoblasts with autologous myoblasts from the patient. These chimeric cells express normal dystrophin and increase functional myoblasts, reduce inflammation, and replace fibrotic tissue, leading to improved muscle strength and function. DEC therapy also minimizes immune response and eliminates the need for immunosuppression, as the cells are recognized as "self." This approach aims to restore dystrophin and prevent the early loss of mobility and premature mortality in DMD patients.²

In the 12-month published data, the study authors wrote that the findings "supports the potential benefits of DT-DEC01 therapy in improving cardiac, respiratory and skeletal muscle function in patients with DMD after systemic-intraosseous administration, providing hope for better outcomes and enhanced quality of life for DMD patients. Additionally, this study also highlights use of EMG as a valuable biomarker for monitoring functional changes in muscles affected by DMD after DT-DEC01 therapy."³

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REFERENCES
1. Siemionow M, Bieganski G, Wachowiak J, et al. Safety and Efficacy of DT‑DEC01 Therapy in Non-Ambulatory Duchenne Muscular Dystrophy Patients up to 24 Months after Systemic Administration. Presented at: 2025 MDA Clinical & Scientific conference; March 16-19. Dallas, TX. ABSTRACT 0163.
2. Chimeric Cells. Dystrogen Therapeutics. https://dystrogen.com/chimeric-cells/. Accessed March 14, 2025.
3. Siemionow M, Bieganski G, Niezgoda A, et al. Safety and Efficacy of DT-DEC01 Therapy in Duchenne Muscular Dystrophy Patients: A 12 - Month Follow-Up Study After Systemic Intraosseous Administration. Stem Cell Rev Rep. 2023;19(8):2724-2740. doi:10.1007/s12015-023-10620-3