MSD has lifted the curtain on strong Phase 3 results in the development of its investigational antiviral drug letermovir, showing the treatment hit its primary endpoint of an improvement in clinically significant cytomegalovirus (CMV) infection following a bone marrow transplant.

A non-nucleoside CMV inhibitor, letermovir is currently in development as a preventative treatment of CVM infection in adult CMV-seropositive patients who have received an allogeneic hematopoietic stem cell transplant (HSCT).

The results showed that, of the 495 trial participants with baseline undetectable plasma CMV DNA, 37.5% of those treated with letermovir developed CMV by week 24, compared to 60.6% for placebo. In addition, the trial results indicate that the drug also led to lower all-cause mortality at 24 weeks, with 9.8% compared to 15.9% for placebo.

Based on the promising results, MSD plans to submit the drug to the US Food and Drug Administration (FDA) and European Medicines Agency (EMA) for approval this year. It had previously been awarded fast track and orphan designations by the FDA.

Matt Fellows