BridgeBio Pharma (Nasdaq: BBIO) announced that the first participant has been dosed in ASCEND-ATTR, a Phase 3b/4 study evaluating the long-term effects of acoramidis on cardiac structure, function, and amyloid burden in patients with transthyretin amyloid cardiomyopathy (ATTR-CM).

ASCEND-ATTR is a single-arm, prospective, open-label study designed to enroll approximately 150 participants. Cardiovascular magnetic resonance (CMR) imaging and cardiac echocardiography will be conducted annually over 36 months. The primary efficacy endpoint is responder status at Month 36, based on improvement from baseline in left ventricular systolic function. Secondary endpoints include CMR and echocardiographic measures of cardiac function, structure, and amyloid burden at Months 12, 24, and 36, along with circulating biomarkers.

The study builds on findings from the CMR substudy of ATTRibute-CM, which indicated that acoramidis treatment was associated with mean improvement from baseline in Left Ventricular Mass Index, Left Ventricular Stroke Volume Index, and Left Ventricular Ejection Fraction through Month 30, with evidence of amyloid regression in a subset of patients.

"Serial cardiac imaging from the ATTRibute-CM CMR substudy gave us the first real signal that TTR stabilization can do more than slow disease progression, it may allow the heart to recover function and remodel favorably over time," said Ahmad Masri, M.D., M.S. of Oregon Health and Science University.

Additional data from the CMR substudy of ATTRibute-CM and its open-label extension, compared to a natural history cohort, are planned to be presented at the European Society of Cardiology Congress 2026.

According to the company's press release, acoramidis is indicated for the treatment of cardiomyopathy of wild-type or variant transthyretin-mediated amyloidosis in adults. Reported adverse reactions included diarrhea (11.6% vs. 7.6% for placebo) and upper abdominal pain (5.5% vs. 1.4% for placebo). Discontinuation rates due to adverse events were similar between groups, at 9.3% and 8.5%, respectively.