Regenxbio announces dose escalation in Phase I/II AFFINITY DUCHENNE trial

Regenxbio announced that the first patient received RGX-202 at dose level 2 in the Phase I/II AFFINITY DUCHENNE trial. RGX-202 is an investigational one-time AAV Therapeutic for Duchenne muscular dystrophy, using the NAV AAV8 vector to deliver a transgene for a novel microdystrophin that includes the functional elements of the C-Terminal domain as well as a muscle-specific promoter to support a targeted therapy for improved resistance to muscle damage associated with Duchenne. Initial biomarker data in two patients who received RGX-202 at dose level 1 who completed three-month assessment demonstrated robust RGX-202 microdystrophin expression with localization to the muscle cell membrane. In recently completed preclinical efficacy studies, RGX-202 at dose level 2 showed improvement in functional performance, compared to dose level 1, as determined by forelimb muscle strength and treadmill exhaustion in mdx mice. Regenxbio expects to share initial strength and functional assessment data for both dose levels and anticipates pivotal dose determination and the initiation of a pivotal program in 2024. The company plans to use RGX-202 microdystrophin expression as a surrogate endpoint to support a Biologics License Application filing using the accelerated approval pathway.