Oral muscular dystrophy drug BBP-418 shows signs of cardiac improvement; exploratory phase 3 analysis still needs long-term validation

The threat posed by muscular dystrophy extends beyond increasing difficulty walking and lifting the arms; whether the heart muscle is also damaged has implications for patients’ long-term health. On October 5, BridgeBio announced a new analysis from the phase 3 trial of its oral drug candidate BBP-418, showing that markers of heart muscle injury returned to the normal range in some patients after one year of treatment, providing preliminary clues about whether the drug can protect the heart.

The data come from the FORTIFY trial’s prespecified 12-month interim assessment in patients with FKRP-related limb-girdle muscular dystrophy, classified as LGMD2I/R9. RTTNews reported that the trial met its prespecified primary and secondary endpoints at the interim analysis; the newly released cardiac results are exploratory analyses, and their strength of evidence cannot be treated as equivalent to that of the prespecified endpoints. Volker Straub of Newcastle University in the United Kingdom presented the data at the World Muscle Society Congress in Hiroshima, Japan.

According to the company’s press release and the content republished by TMCnet, 25 of the 109 participants with relevant testing data had elevated high-sensitivity cardiac troponin I at baseline. This blood marker can reflect heart muscle injury. Among patients with elevated baseline levels, all those in the BBP-418 group returned to the normal range at month 12, compared with 40% in the placebo group, with a company-reported p-value of 0.0248. “All” refers to a specific small subgroup of patients and cannot be interpreted as meaning that every trial participant’s heart had returned to normal.

Another observation involved left ventricular ejection fraction (LVEF), the proportion of blood in the left ventricle pumped out with each contraction. At baseline, 18 of the 105 participants with relevant data had an LVEF below 50%. The company also reported that at month 12, 54% of patients in the BBP-418 group had stable or improved LVEF, compared with 25% in the placebo group (p = 0.0262). This comparison provides clues about cardiac function, but “stable or improved” does not mean a return to normal and is insufficient to demonstrate a reduction in the risk of heart failure.

The limitations of the analysis are central to interpreting these figures. The company acknowledged that the relevant samples were small and that the exploratory analyses did not control the overall type I error rate; when multiple outcomes are tested simultaneously, the likelihood of finding a favorable difference by chance increases. A return of troponin to the normal range may not predict long-term clinical benefit. Longer follow-up and supporting clinical outcomes are still needed to establish whether the drug truly changes the course of cardiac disease.

This news is based primarily on data released by the company. TMCnet published the same press release, which cannot be considered independent validation; RTTNews separately reported on the trial’s progress and regulatory timeline. BBP-418 is currently under priority review by the U.S. Food and Drug Administration, with a target decision date of November 27, 2026. This is a scheduled review milestone; whether approval will be granted remains for the regulator to decide.

BridgeBio also plans to initiate a study in LGMD2I/R9 patients younger than 12 in the first half of 2027 and advance trials in other subtypes, including LGMD2M/R13 and LGMD2U/R20. These plans will extend research to different ages and disease backgrounds, but the current results cannot yet be directly applied to those populations. For current patients, the new data offer a specific signal of cardiac protection worth investigating, while long-term benefits still need to be established by subsequent evidence.