US-based biotechnology company REGENXBIO Inc (Nasdaq: RGNX) announced on Thursday the publication of preclinical results comparing a microdystrophin gene therapy construct that included the C-terminal (CT) domain to a microdystrophin construct without the CT domain.

The company says that the results, which were published in peer-reviewed journal Molecular Therapy Methods and Clinical Development, showed that the microdystrophin with the CT domain improved functional benefit compared to the microdystrophin without, supporting the potential of RGX-202 to drive functional improvements in patients with Duchenne Muscular Dystrophy.

According to REGENXBIO, RGX-202 is the only investigational or approved microdystrophin gene therapy candidate for the treatment of Duchenne that includes the CT domain, a key portion of dystrophin, making it the closest to naturally occurring dystrophin.

In this paper, titled 'Enhanced therapeutic potential of a microdystrophin with an extended C-terminal domain', two AAV vectors, one encoding a microdystrophin protein with the CT domain and one encoding an otherwise equivalent microdystrophin protein without the CT domain, were evaluated across three studies in mdx mice, a preclinical model of Duchenne, to measure muscle force, protein levels, and protection from contraction-induced muscle injury.

REGENXBIO is enrolling participants in the pivotal portion of the Phase I/II/III AFFINITY DUCHENNE trial of RGX-202 and expects to submit a Biologics License Application (BLA) using the accelerated approval pathway in mid-2026.