Alnylam Pharmaceuticals disclosed new findings from a post-hoc analysis of the Phase 3 HELIOS‑B trial involving its RNA interference therapy AMVUTTRA (vutrisiran) for adults with wild-type or hereditary transthyretin-mediated amyloidosis with cardiomyopathy (ATTR-CM). According to the company, results presented at the American Heart Association Scientific Sessions 2025 demonstrate favorable changes in key measures of cardiac structure and function as well as renal outcomes.
The company said that in a cohort of patients evaluated using cardiovascular magnetic resonance (CMR) imaging, treatment with vutrisiran was associated with a reduction in extracellular volume (ECV)—a proxy for amyloid burden—with 22 % of treated patients showing regression at Year 3 versus 0 % in the placebo group. The analysis also found that treatment attenuated increases in left ventricular mass index and maintained ejection fraction and stroke volume compared with placebo.
Alnylam noted that echocardiographic data from the wider patient population indicated that patients on vutrisiran experienced less worsening in left atrial strain and right ventricular free wall strain over 30 months relative to those receiving placebo. The company claims these structural and functional improvements affirm the therapy’s disease-modifying potential.
In addition, the analysis evaluated renal outcomes in patients who progressed to chronic kidney disease (CKD) Stage 4 or greater during the trial. The company said that in this subgroup, vutrisiran treatment reduced the risk of all-cause mortality and cardiovascular events with a hazard ratio of 0.47 compared with placebo, and fewer treated patients suffered ≥40 % declines in estimated glomerular filtration rate (eGFR).
Alnylam said that these data build upon earlier results showing vutrisiran’s ability to reduce cardiovascular mortality, hospitalizations and urgent heart failure visits in ATTR-CM. The company stated it believes the findings further support the use of vutrisiran in earlier stages of disease and strengthen its profile as a comprehensive therapy for this complex, multisystem disorder.
