Losmapimod, a p38 MAPK inhibitor, did not reduce the risk of recurrent major adverse cardiovascular (CV) events in patients hospitalized with acute myocardial infarction (MI), a recent study published in JAMA has reported.

A previous Phase 2 trial in patients with non-ST elevation MI (STEMI) showed that losmapimod may reduce inflammation and improve outcomes. Michelle L. O’Donoghue, MD, MPH, of Brigham and Women’s Hospital, and colleagues studied the efficacy and safety of losmapimod on CV outcomes in patients hospitalized after a heart attack in the Phase 3 trial. Patients who were hospitalized with an acute MI and at least 1 predictor of CV risk were randomized to either twice-daily losmapimod (n=1,738) or matching placebo (n=1,765) on a background of guideline-recommended therapy for 12 weeks.

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Part A of the study consisted of a group (n=3,503) to provide an initial assessment of safety and exploratory efficacy before moving forward to Part B consisting of approximately 22,000 patients. The primary endpoint was a composite of CV death, MI, or severe recurrent ischemia requiring urgent coronary revascularization with the principal analysis specified at Week 12. Among patients in Part A, the primary endpoint was achieved in 7% of patients in the placebo group (n=123) vs. 8.1% of patients in the losmapimod group (n=139).

On-treatment rates of serious adverse events were slightly higher in the losmapimod group vs. the placebo group (16% vs.14.2%).

Study authors concluded that the findings from this exploratory efficacy “did not justify proceeding to a larger efficacy trial in the existing patient population.” In addition, losmapimod was not found to reduce the incidence of any secondary outcomes, including all-cause mortality. They added that the study findings do not support p38 MAPK inhibition with losmapimod as a treatment strategy for patients hospitalized with MI. 

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