Merck Kicks Off Phase 3 Study Of CMV Drug Letermovir

Merck announced that it has initiated the global Phase III study of its investigational antiviral agent letermovir (MK-8828).

Letermovir is an experimental once-daily antiviral drug intended for the prevention of human cytomegalovirus (CMV) infection in at-risk patients. The antiviral agent is derived from quinazolines and inhibits the human CMV viral terminase. Merck acquired the rights to develop and market letermovir from AiCuris in October 2012. Since then, the U.S. Food and Drug Administration (FDA) and European Medicines Agency (EMA) have granted Orphan status to letermovir for the prevention of CMV viremia. The FDA has also designated Fast Track status to letermovir, which makes it eligible for a faster development and review process.

CMV can cause severe, deadly infections in immuno-compromised patients, such as transplant recipients. The infection is characterized by fever, plummeting white blood cell counts and platelet numbers, with or without organ dysfunction. The infection can be prevented through prophylaxis or pre-emptive treatment of patients manifesting evidence of CMV viremia.

The first patient has been enrolled in the multi-center, placebo controlled, randomized study that will evaluate the safety and efficacy of letermovir. The trial will involve patients 18 years old and above who are CMV-seropositive recipients of allogeneic hematopoietic stem cell transplants.

Dr. Michele Trucksis, Executive Director of Infectious Diseases at Merck Research Laboratories, said, “There remains a need for additional therapeutic options in the prevention of CMV infection in high-risk patients. Merck is pleased to initiate this global Phase 3 study with letermovir.”

The primary endpoint of the trial will measure the percentage of participants taking letermovir with clinically significant CMV infection during the 24 weeks after receiving bone marrow transplant against those taking a placebo. Merck said it anticipates enrolling about 540 patients in the study across 70 clinical sites in 20 countries including the U.S.

Prof. Helga Rübsamen-Schaeff, CEO of AiCuris, remarked, “This study marks a very important step in the development of letermovir and for AiCuris as licensor of this compound. We are very excited to have reached this stage and look forward to the results.”

The study is expected to be completed by July 2017.