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]

Financial Data and Key Metrics Changes - REGENXBIO ended the quarter on March 31, 2025, with cash, cash equivalents, and marketable securities of $272 million, an increase from $245 million as of December 31, 2024, primarily driven by a $110 million upfront payment from the Nippon Shinyaku collaboration [24] - R&D expenses were $53 million for the quarter ended March 31, 2025, compared to $54.8 million for the same quarter in 2024, reflecting a decrease due to clinical trial expenses for RGX-314 and RGX-202 [25] Business Line Data and Key Metrics Changes - RGX-121, a potential first gene therapy for MPS II, is on track for potential FDA approval in the second half of 2025, with a BLA submitted under the accelerated approval pathway [8][9] - RGX-202, a next-generation candidate for Duchenne muscular dystrophy (DMD), has surpassed 50% enrollment in its pivotal study and is expected to submit a BLA in mid-2026 [10][11] - The retinal program, RGX-314, is advancing in two pivotal studies for wet AMD and is on track to be the first gene therapy on the market for this condition [12][19] Market Data and Key Metrics Changes - The DMD market is projected to have over half of the prevalent population untreated by 2027, highlighting a significant opportunity for RGX-202 [11] - The wet AMD and diabetic retinopathy markets represent large multibillion-dollar commercial opportunities, with RGX-314 positioned to serve as a meaningful alternative to current treatments [12][19] Company Strategy and Development Direction - The company is focused on transitioning to a commercial stage with in-house manufacturing capabilities and plans to secure non-dilutive funding [6][8] - A strategic partnership with Nippon Shinyaku aims to commercialize the neurodegenerative franchise, including RGX-121 and RGX-111 [9] - The company is preparing for commercial supply manufacturing of RGX-202 in anticipation of a 2027 launch [11][27] Management's Comments on Operating Environment and Future Outlook - Management expressed confidence in the imminent acceptance of the BLA for RGX-121 and the positive trajectory of clinical programs [34][51] - The company is optimistic about the evolving regulatory landscape and the potential for accelerated approval pathways, particularly in light of recent developments in the industry [36][44] Other Important Information - The company has a robust cash runway expected to fund operations into the second half of 2026, with potential extensions through non-dilutive financing options [25][26] - The manufacturing innovation center in Rockville, Maryland, is capable of producing up to 2,500 doses of RGX-202 annually, ensuring readiness for market needs [11][12] Q&A Session Summary Question: Timing for the Hunter BLA - Management indicated that the BLA acceptance is imminent and they feel confident about the review process [34] Question: Competitor Insights and Regulatory Expectations - Management discussed the evolving expectations for accelerated approval in DMD, emphasizing the strength of their safety and functional data [36][44] Question: Changes in FDA Requirements - Management noted that there are no anticipated changes in the accelerated approval pathway and enrollment is on track [43][44] Question: Planning for Diabetic Retinopathy Phase III Trial - Management confirmed ongoing interactions with the FDA and that they are on track for first patient dosing this year [55] Question: Updates on DMD Functional Data - Management plans to release additional functional data in the first half of the year, focusing on dose level two patients [62][88] Question: Impact of Recent Pricing Announcements - Management stated it is too early to assess the impact of recent pricing discussions on their gene therapies [104]