BridgeBio shares preliminary findings on glycosylated alpha-dystroglycan

BridgeBio Pharma announced the Company’s novel validated muscle tissue-based bioassay, which measures the amount of glycosylated alpha-dystroglycan, alphaDG, in patients with LGMD2I, at the MDA 2023 Annual Meeting. Additionally, BridgeBio shared updated results at Month 15 for its Phase 2 clinical trial and the design for its pivotal Phase 3 study for patients with LGMD2I. The novel bioassay was developed by BridgeBio to measure the amount of glycosylated alphaDG, and to evaluate the impact of BBP-418 treatment. When deficient, glycosylated alphaDG is the direct cause of muscle breakdown in LGMD2I. The bioassay allowed the Company to evaluate natural history and Phase 2 data to inform the Phase 3 study design. Highlights of the results include: Development of a novel, validated, quantitative method to measure glycosylated alphaDG in muscle; Observation of ~90% reduction in glycosylated DG in muscle biopsies from patients with LGMD2I compared to healthy individuals; Higher glycosylated DG in L276I/L276I homozygous patients who are characterized by a milder clinical phenotype than other fukutin-related protein genotypes; Stable glycosylated DG levels in untreated patients with LGMD2I over ~6-12 months. Additionally, BridgeBio presented 15-month results from its ongoing Phase 2 trial and the design of its registration-enabling Phase 3 study. Phase 2 study results showed: Increased glycosylation of alphaDG was observed following treatment initiation with BBP-418, with an approximate doubling of glycosylated alphaDG at 3 months which was sustained over 15 months; Greater than 70% reduction in CK sustained at 15 months; Improvements from baseline in NSAD test scores and ambulatory measures at 15 months; No treatment-related serious adverse events or dose limiting toxicities were observed with BBP-418.