Core Insights - REGENXBIO Inc. announced preclinical results showing that a microdystrophin gene therapy construct with the C-terminal (CT) domain provides improved functional benefits for patients with Duchenne Muscular Dystrophy compared to a construct without the CT domain [1][4][5] - RGX-202 is the only investigational microdystrophin gene therapy candidate that includes the CT domain, making it closest to naturally occurring dystrophin [2][8] Group 1: Research Findings - The preclinical study published in Molecular Therapy Methods and Clinical Development demonstrated that the microdystrophin with the CT domain was maintained at higher levels in transduced muscles and effectively recruited the dystrophin-associated protein complex to the muscle membrane [4][5] - The incorporation of the CT domain enhances the microdystrophin design, allowing for higher accumulation levels in muscle and potentially improving functional benefits [5][7] Group 2: Clinical Trial Insights - Interim results from the Phase I/II AFFINITY DUCHENNE trial indicated that RGX-202 showed consistent evidence of positively changing the disease trajectory in patients with Duchenne and had a favorable safety profile [5][6] - REGENXBIO is currently enrolling participants in the pivotal portion of the Phase I/II/III AFFINITY DUCHENNE trial and plans to submit a Biologics License Application (BLA) via the accelerated approval pathway in mid-2026 [6][9] Group 3: Company Overview - REGENXBIO is a biotechnology company focused on gene therapy, with a late-stage pipeline that includes RGX-202 for Duchenne, among other treatments for rare diseases [11] - The company has pioneered AAV gene therapy since its founding in 2009 and has treated thousands of patients with its AAV platform [11]

PBFT02 Development and Preclinical Results - PBFT02 is an AAV gene therapy designed to deliver functional PGRN to the brain for the treatment of FTD-GRN [13] - In Grn-/- mice, AAV.hGRN vector ICV administration improved lysosomal function, reduced lipofuscin fluorescence in the thalamus, and reduced brain hexosaminidase activity [21, 23] - AAV1 was selected as the vector serotype due to superior hPGRN levels in CSF compared to AAV5 and AAVhu68 in NHPs [28, 29] - In Grn-/- mice, PBFT02 reduced lipofuscin deposition and neuroinflammation in the brain after intra-CSF delivery [34, 37] - ICM administration of PBFT02 enables PGRN delivery throughout the CNS [40] - In NHPs, PBFT02 dose-dependently increased PGRN in CSF up to day 14 [46, 48] - In NHPs, PBFT02 at Dose 1 resulted in approximately 10e4 GC/ug DNA throughout the brain [43] Clinical Trial (upliFT-D) and Safety - The upliFT-D trial is a global Phase 1/2 multi-center, open-label, dose-escalation study with PBFT02 [52, 55] - FTD-GRN Cohort 1 (n = 5) dosing is complete [56] - All four Cohort 1 participants who received a revised immunosuppression regimen had no SAEs or significant immune responses [57] - Cohort 1 interim data shows PBFT02 administration leads to robust and sustained increases in CSF PGRN [58]

Regenxbio (RGNX) Q1 2025 Earnings Call May 12, 2025 04:30 PM ET Company Participants Patrick Christmas II - Chief Legal OfficerCurran Simpson - Board Member, President & CEOSteve Pakola - Chief Medical OfficerMitchell Chan - CFOMani Foroohar - Senior Managing DirectorGena Wang - MD - Biotech Equity ResearchTejas Wein - Associate Director - Biotechnology Equity ResearchAnnabel Samimy - Managing DirectorShelby Hill - Biotech Equity Research AssociateSean McCutcheon - Vice President - Biotechnology Equity Rese ...