Merck Reports Results Of Pivotal Phase 3 Clinical Study Of Letermovir

(RTTNews) - Merck & Co., Inc. (MRK) announced results of the pivotal Phase 3 clinical study of letermovir, an investigational antiviral medicine for the prevention of clinically-significant cytomegalovirus (CMV) infection in adult (18 years and older) CMV-seropositive recipients of an allogeneic hematopoietic stem cell transplant (HSCT), also known as bone marrow transplant (BMT).

The study met its primary efficacy endpoint, showing that significantly fewer patients with undetectable CMV DNA at the start of study treatment developed clinically significant CMV infection through Week 24 post-HSCT (using a non-complete equals failure approach, in which patients who discontinued from the study prior to Week 24 post-transplant or had a missing outcome at Week 24 post-transplant were counted as failures).

In the study, letermovir prophylaxis was associated with lower all-cause mortality through Week 24 post-HSCT. Based on these results, Merck plans to submit regulatory applications for the approval of letermovir in the United States and European Union (EU) in 2017.

CMV is the most common clinically significant viral infection in allogeneic HSCT recipients. HSCT is a medical procedure in the field of hematologic oncology, most often performed for the treatment of patients with certain cancers of the blood or bone marrow, such as leukemia and lymphoma. While preemptive therapy (treatment when CMV DNA is detected in the blood) with antiviral medicines can reduce the incidence of CMV disease, CMV reactivation post-HSCT is associated with higher mortality despite the use of preemptive therapy.