Influence of Disease-Modifying Therapy on the Efficacy of Vutrisiran in Transthyretin Cardiac Amyloidosis

Background: Vutrisiran, an RNA interference therapeutic, reduced all-cause mortality and recurrent cardiovascular events in patients with transthyretin amyloid cardiomyopathy (ATTR-CM) in the HELIOS-B trial. Whether concomitant disease-modifying or heart failure therapy modifies the efficacy of vutrisiran has not been described. Objectives: We aimed to characterize patterns of concomitant therapy use in HELIOS-B, describe medication initiation rates by treatment arm, and evaluate whether concomitant therapy modified vutrisiran's treatment effect. Methods: In HELIOS-B, 654 randomized patients with ATTR-CM received vutrisiran or placebo. We assessed baseline use and postrandomization initiation of tafamidis, sodium-glucose cotransporter-2 (SGLT2) inhibitors, mineralocorticoid receptor antagonists (MRA), beta-blockers, and renin-angiotensin system inhibitors (angiotensin-converting enzyme inhibitors/angiotensin receptor blockers/angiotensin receptor-neprilysin inhibitors), and used time-updated Lin-Wei-Yang-Ying models to evaluate treatment effect modification on the primary composite endpoint of all-cause mortality and recurrent cardiovascular events. Results: At baseline, 40% of participants were receiving tafamidis and 77% at least 1 heart failure medication. MRAs and SGLT2 inhibitors were the most frequently initiated therapies during follow-up, with initiation rates numerically higher across all heart failure medication classes in the placebo group. There was no statistically significant evidence that the treatment effect of vutrisiran was modified by baseline or time-updated use of any medication class (P-interaction: tafamidis 0.95, SGLT2 inhibitors 0.59, MRA 0.92, beta-blockers 0.75, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers/angiotensin receptor-neprilysin inhibitors 0.82). Conclusions: In HELIOS-B, there was no statistically significant evidence that the treatment benefit of vutrisiran on all-cause mortality and recurrent cardiovascular events was modified by concomitant use of tafamidis or heart failure therapies. These findings support the consistency of vutrisiran's efficacy across the spectrum of contemporary ATTR-CM pharmacotherapy. (HELIOS-B: A Study to Evaluate Vutrisiran in Patients With Transthyretin Amyloidosis With Cardiomyopathy; NCT04153149).