Vutrisiran in Patients with Transthyretin Amyloidosis with Cardiomyopathy

BACKGROUNDTransthyretin amyloidosis with cardiomyopathy (ATTR-CM) is a progressive, fatal disease. Vutrisiran, a subcutaneously administered RNA interference therapeutic agent, inhibits the production of hepatic transthyretin. METHODSIn this double-blind, randomized trial, we assigned patients with ATTR-CM in a 1:1 ratio to receive vutrisiran (25 mg) or placebo every 12 weeks for up to 36 months. The primary end point was a composite of death from any cause and recurrent car-diovascular events. Secondary end points included death from any cause, the change from baseline in the distance covered on the 6-minute walk test, and the change from baseline in the Kansas City Cardiomyopathy Questionnaire-Overall Summary (KCCQ-OS) score. The efficacy end points were assessed in the overall population and in the monotherapy population (the patients who were not receiving tafamidis at baseline) and were tested hierarchically. RESULTSA total of 655 patients underwent randomization; 326 were assigned to receive vutri-siran and 329 to receive placebo. Vutrisiran treatment led to a lower risk of death from any cause and recurrent cardiovascular events than placebo (hazard ratio in the overall population, 0.72; 95% confidence interval [CI], 0.56 to 0.93; P = 0.01; hazard ratio in the monotherapy population, 0.67; 95% CI, 0.49 to 0.93; P = 0.02) and a lower risk of death from any cause through 42 months (hazard ratio in the overall population, 0.65; 95% CI, 0.46 to 0.90; P = 0.01). Among the patients in the overall population, 125 in the vutrisiran group and 159 in the placebo group had at least one primary end-point event. In the overall population, treatment with vutrisiran resulted in less of a decline in the distance covered on the 6-minute walk test than placebo (least-squares mean difference, 26.5 m; 95% CI, 13.4 to 39.6; P<0.001) and less of a decline in the KCCQ-OS score (least-squares mean difference, 5.8 points; 95% CI, 2.4 to 9.2; P<0.001). Similar benefits were observed in the monotherapy population. The incidence of adverse events was similar in the two groups (99% in the vutrisiran group and 98% in the placebo group); serious adverse events occurred in 62% of the patients in the vutrisiran group and in 67% of those in the placebo group. CONCLUSIONSAmong patients with ATTR-CM, treatment with vutrisiran led to a lower risk of death from any cause and cardiovascular events than placebo and preserved func-tional capacity and quality of life. (Funded by Alnylam Pharmaceuticals; HELIOS-B ClinicalTrials.gov number, NCT04153149.)