Regenxbio (RGNX) Status Update summary

Disease Overview and Unmet Need

• Duchenne muscular dystrophy (DMD) is a severe, progressive muscle disease caused by DMD gene mutations, affecting approximately 15,000 in the US and 1 in 3,500 to 5,000 boys globally, leading to loss of movement, respiratory issues, cardiomyopathy, and early death.

• There is significant unmet need for gene therapies with favorable safety and efficacy profiles for DMD.

RGX-202 Therapeutic Approach and Trial Design

• RGX-202 is a differentiated gene therapy encoding key regions of dystrophin, including the C-Terminal domain, delivered via NAV AAV8 vector, aiming to improve muscle function and reduce immunogenicity.

• The therapy is supported by industry-leading manufacturing with over 80% full capsids and a proactive, short-course immune modulation regimen to enhance safety.

• The Phase I/II AFFINITY DUCHENNE trial enrolled boys aged 1–12, with dose escalation and expansion, and primary endpoints of safety and microdystrophin expression.

Clinical Trial Progress and Enrollment

• The pivotal phase of the AFFINITY DUCHENNE trial is over 50% enrolled, with completion expected this year and potential FDA approval targeted for the first half of 2027.

• Enrollment is robust across a broad age range (1+ years), with high demand and enthusiasm from the Duchenne community and physicians.

• The trial has expanded to include a wider range of patients, aiming for a broad label and accelerated approval.

• The pivotal phase is enrolling approximately 30 patients, with more than half already enrolled, aiming for a Biologics License Application submission in mid-2026.