BridgeBio Pharma (Nasdaq: BBIO) presented exploratory cardiac data from the Phase 3 FORTIFY trial of BBP-418, an oral investigational therapy for limb-girdle muscular dystrophy type 2I/R9 (LGMD2I/R9), at the 31st annual Congress of the World Muscle Society in Hiroshima, Japan.

Among trial participants with elevated high-sensitivity troponin I at baseline, 100% of those treated with BBP-418 returned to the normal range by Month 12, compared with 40% in the placebo arm (p=0.0248). High-sensitivity troponin I, a blood marker of heart muscle injury, declined more in the BBP-418 group than in the placebo group, with a least-squares mean difference of -17.8 ng/L (95% CI: -35.1 to -0.5; p=0.0443).

Left ventricular ejection fraction (LVEF) was stable or improved in 54% of BBP-418-treated participants at Month 12 versus 25% in the placebo arm (p=0.0262). Cardiomyopathy affects approximately 30% of individuals with LGMD2I/R9 and progresses at an annual rate of approximately 0.4% loss of LVEF.

Separately presented data showed that BBP-418 increased mean glycosylated alpha-dystroglycan by Month 3 to levels observed in asymptomatic carriers of the FKRP gene mutation, who do not exhibit disease symptoms. That result was sustained through Month 12.

"Cardiac involvement is a major driver of morbidity and mortality in LGMD2I/R9," said Volker Straub, M.D., Ph.D. of Newcastle University, UK, who presented the data. "What stands out in this analysis is how consistent it is: high-sensitivity troponin I fell and, in those who entered the study with elevated levels, it normalized; ejection fraction stabilized; and this happened alongside walking farther and breathing better."

BBP-418 previously met all primary and secondary endpoints at the pre-specified 12-month interim analysis of FORTIFY. The drug is under FDA Priority Review with a PDUFA target action date of November 27, 2026. BridgeBio states it plans to initiate clinical studies of BBP-418 in patients under 12 years of age in the first half of 2027. Approximately 7,000 individuals in the U.S. and Europe live with LGMD2I/R9 and other addressable alpha-dystroglycanopathies.