ESC26: Cytokinetics' big data reveal for Myqorzo impresses

Cytokinetics has revealed the highly anticipated data from the ACACIA-HCM study of Myqorzo, which promises to take the cardiac myosin inhibitor into new territory for the class.

First teased in May, ACACIA-HCM could double the target market for Myqorzo (aficamten), expanding its use from its current approval in obstructive hypertrophic cardiomyopathy (HCM) to include non-obstructive forms of the disease.

Crucially for Cytokinetics, its only rival in the class – Bristol Myers Squibb's first-to-market Camzyos (mavacamten) – was unable to show a significant improvement in non-obstructive HCM in the ODYSSEY-HCM trial.

The ACACIA-HCM results presented at the ESC congress, and simultaneously published in the New England Journal of Medicine (NEJM), reveal that Myqorzo achieved a 3-point improvement over placebo on the Kansas City Cardiomyopathy Questionnaire Clinical Summary Score (KCCQ-CSS) scale, which charts patient-reported scores on physical functioning and the burden of symptoms like shortness of breath, chest pain, and fatigue, after 36 weeks.

By 72 weeks, the difference between Myqorzo and placebo on KCCQ-CSS had risen to 7 points, which represents a moderate-to-large, clinically meaningful improvement in symptoms and physical capacity that should make it easier for patients to walk or climb stairs and carry out their daily activities.

Moreover, there was also a statistically significant 0.67 mL/kg/min improvement in peak oxygen uptake (pVO2), a biomarker used to measure exercise capacity, at the same timepoint for Myqorzo versus the control group. That came in well above the 0.35 mL/kg/min threshold for a patient to start seeing a real-world functional improvement.

"ACACIA-HCM is the first-ever positive clinical trial in non-obstructive HCM," said Stephen Heitner, Cytokinetics' chief medical officer, who described the results as "statistically robust, consistent across prespecified subgroups and other secondary endpoints, and clinically impactful for these patients."

The readout puts Cytokinetics in pole position to bring the first treatment for non-obstructive HCM to market, which could double the number of patients eligible for its drug. Myqorzo launched in the US in January and has also been approved in Europe and China, with sales reaching around $25 million in its first full quarter on the market.

Camzyos, which was approved by the FDA for obstructive HCM in 2022, broke the blockbuster barrier last year with a 77% rise in annual sales to reach almost $1.1 billion. Analysts have predicted that approval in both forms of HCM could see Myqorzo easily overtake its rival and bring in peak sales of around $4 billion a year.