New findings from long-term treatment bode well for mavacamten. This is because if the drug is used in standard practice to avoid the need for surgery or an invasive procedure to reduce the patient’s left ventricular outflow obstruction, the duration of mavacamten treatment will probably need to be extended for many years and even for decades, he said. Florian Rader, MD, who presented the results at the annual scientific sessions of the American College of Cardiology. “In practice, mavacamten will probably be used for many, many years, especially as it replaces septal reduction therapy, so we need long-term data,” Dr Rander told a news conference. “I’m very pleased with the long – term data” in the follow – up study. The Food and Drug Administration is currently considering whether to approve mavacamten for routine marketing for the treatment of patients with symptomatic obstructive hypertrophic cardiomyopathy (oHCM), with a decision expected at the end of April 2022. The study mentioned by Dr. Rader monitored 231 patients with symptomatic oHCM who had completed the baseline 30-week trial of mavacamten, EXPLORER-HCM, and chose to continue open extended mavacamten therapy, either continuing treatment initiated during the trial or switching to mavacamten after taking placebo during the test. The main findings from EXPLORER-LTE (long-term extension) were that continued treatment for about 62 weeks maintained the safety and efficacy findings observed at the end of the blind, randomized initial 30-week phase, said Dr. , co-director of the Hypertrophic Cardiomyopathy and Aortopathy Clinic at Cedars-Sinai Medical Center in Los Angeles.
“Almost revolutionary”
Mavacamten represents “an almost revolutionary change” in the treatment of oHCM, said Maya E. Guglin, MD, a professor of clinical medicine and advanced heart failure at Indiana University in Indianapolis. “Until now, there has been no good medical treatment for symptomatic oHCM. This will change the landscape and will undoubtedly change the guidelines for the treatment of oHCM,” Dr. Guglin told a news conference. “All of us who care for patients with oHCM have been looking forward to having a disease-specific treatment. It is encouraging to see that safety and efficacy have remained high with long-term follow-up,” said Kyle W. Klarich, MD, MD, professor and cardiologist at treatment of HCM patients at the Mayo Clinic in Rochester, Minn. Mavacamten is a direct myosin inhibitor that reduces the excessive number of myosin-actin bridges that form in patients with oHCM, and therefore directly targets the pathophysiology underlying the disorder, Dr. Rader explained. Patients receiving mavacamten included in the long-term extension reported by Dr. Rader was on average 60 years old and 61% were men. They had an average drop of 35.6 mm Hg in the left ventricular outflow tract (LVOT) grade after 48 weeks of treatment and a decrease of 32.8 mm Hg after 84 weeks. When the researchers measured their LVOT inclination during a valsalva maneuver, their reductions from baseline averaged 45.3 mm Hg after 48 weeks and 46.4 mm Hg after 84 weeks. The left ventricular ejection fraction at rest also decreased, averaging 7.0 percentage points from baseline after 48 weeks and averaging 9.0 percentage points after 84 weeks. After 48 weeks of treatment, 68% of patients showed an improvement of at least one category from baseline to the functional category of the New York Heart Association. Safety results showed that most treatment-related side effects were mild or moderate and approximately 2% of patients had a severe drug-related side effect. Ten of the 231 patients discontinued mavacamten due to a treatment-related adverse reaction. EXPLORER-HCM and EXPLORER-LTE were funded by MyoKardia, the company that develops mavacamten and is now owned by Bristol-Myers Squibb. Dr. Rader has been a consultant to MyoKardia as well as Medtronic and ReCor. Dr. Guglin and Dr. Klarich had no revelations. This article first appeared on MDedge.com, part of the Medscape Business Network.
