The cardiac myosin inhibitor mavacamten has been approved in all European Union (EU) member states for use in adult patients with symptomatic (NYHA class II-III) obstructive hypertrophic cardiomyopathy (HCM). This approval is based on the positive results from two phase 3 trials, EXPLORER-HCM and VALOR-HCM. Mavacamten is a allosteric and reversible inhibitor selective for cardiac myosin.

The EXPLORER-HCM and the VALOR-HCM trials were double-blind, randomized, placebo-controlled phase 3 trials enrolling patients with symptomatic, obstructive HCM.

In the EXPLORER-HCM trial, the primary endpoint -a composite functional endpoint of the proportion of patients who achieved either improvement of mixed venous oxygen tension (pVO₂) by ≥1.5 mL/kg/min plus improvement in NYHA class by at least 1 or improvement of pVO₂ by ≥3.0 mL/kg/min plus no worsening in HYHA class at week 30 – was achieved in 37% of patients taking mavacamten vs. 17% in patients on placebo (difference of 19.4%, 95%CI:8.67-30.13, P=0.0005).

The VALOR-HCM trial showed that treatment with mavacamten resulted in reduction of the primary composite endpoint -the patient’s decision to proceed with SRT prior to or at week 16 or patients who remain SRT eligible at week 16. 17.9% of patients treated with mavacamten vs. 76.8% of patients in the placebo group decided to proceed with SRT prior to or at week 16 or were SRT-eligible at week 16 (difference of 58.9%, 95%CI:44.0%-73.9%, P<0.0001).

Pooled safety data showed that the most commonly reported adverse reactions were dizziness, dyspnea, systolic dysfunction and syncope.

Source: press release Bristol Myers Squibb, June 26, 2023