MyoKardia Announces Positive Topline Results for Targeted Cardiomyopathy Drug

Hypertrophic cardiomyopathy (HCM) is a condition where heart walls become thick making it difficult for the heart to pump the blood. An obstructive and most common form of the disorder results in the thickening of the walls separating the two bottom chambers of the heart. This blocks or reduces the blood flow from the left ventricle to the aorta leading to sudden heart failure, life-threatening arrhythmias, and sudden cardiac death. The most frequent cause of HCM is a mutation in the myosin protein that regulates the contraction of heart muscles.

Currently, there is no targeted treatment for HCM. However, treatment with beta-blockers and calcium channel blockers is practiced regularly as it can relieve the symptoms of HCM by reducing the heart rate. To target this condition, a clinical-stage biopharmaceutical company, MyoKardia has developed an allosteric modulator of cardiac myosin known as Mavacamten that could dampen cardiac contractions by inhibiting excessive myosin movements associated with contractions.

On 11th May, MyoKardia announced positive topline results from the Phase 3 EXPLORER-HCM clinical trial of mavacamten for the treatment of patients with symptomatic, obstructive hypertrophic cardiomyopathy. The study showed significant improvement in oxygen uptake, the primary endpoint of the study along with improvements in symptoms, functional status, and quality of life. More importantly, reduction or complete elimination in obstruction of the left ventricle was observed with the drug treatment. Although the company hasn’t revealed the data, it will form the basis of New Drug Application that MyoKardia plans to file with the USFDA in the first quarter of 2021.

Dr. Iacopo Olivotto, M.D., Careggi University Hospital and lead clinical investigator for the EXPLORER-HCM clinical trial said, “HCM is the most common inherited cardiovascular disease, and patients face an uncertain journey that all too frequently includes debilitating symptoms, as well as serious complications, such as heart failure, stroke and cardiac arrest. Mavacamten is the first drug developed to target the specific molecular defect of the disease. EXPLORER represents a major achievement toward a precision-medicine approach in cardiomyopathies and should provide great hope to a community painfully aware of the lack of disease-specific treatment options.”

Explorer-HCM Trial

This trial is MyoKardia’s pivotal program that evaluated Mavacamten as a treatment for symptomatic obstructive hypertrophic cardiomyopathy. A total of 251 patients were enrolled in the study for 30 weeks. In patients with heart diseases, peak oxygen uptake (peakVO2) is the standard for assessing cardiovascular fitness, which determines the maximum amount of oxygen one can consume during exercise. The Explorer trial determined whether the drug could improve this parameter. The trial also evaluated improvements in NYHA functional class, a tool for heart failure risk assessment, which is based on the severity of symptoms. An achievement of peakVO2 value greater or equal to 1.5ml/kg/min with the improvement of ≥1 NYHA functional class or a peakVO2 of 3.0ml/kg/min with no worsening in NYHA functional class was considered a positive response.

The study also assessed mavacamten’s effect on health-related quality of life and severity of symptoms till week 30 by analyzing echocardiographic indices, circulating biomarkers, cardiac rhythm patterns, and accelerometry. Clinically meaningful improvements were observed for the drug over placebo in addition to a positive safety profile.

“The resoundingly positive data from EXPLORER bring us a significant step closer to improving the lives of people with serious cardiovascular conditions, starting with HCM, a debilitating disease estimated to affect one in every 500 people,” said Tassos Gianakakos, Chief Executive Officer of MyoKardia. “The activity and tolerability profile observed for mavacamten in this pivotal study underscores the profound impact and potential for therapeutics that target the underlying biology of disease.

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References

1. http://investors.myokardia.com/news-releases/news-release-details/myokardia-announces-primary-and-all-secondary-endpoints-met
2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5654557/

Author

Ruchi Jhonsa