Healthcare firm Merck has reported positive results from the Phase III clinical trial of anti-viral drug letermovir to prevent cytomegalovirus (CMV) infection in recipients of bone marrow transplant.

Letermovir is an investigational, once-daily anti-viral medicine being developed to prevent CMV infection and disease.

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A member of the non-nucleoside CMV inhibitors (3,4 dihydro-quinazolines) class, the drug targets the viral terminase complex and blocks viral replication.

The trial met its primary efficacy endpoint, which indicated that few patients with undetectable CMV DNA at the start of study treatment developed clinically significant CMV infection after treatment.

The randomised Phase III trial was conducted in CMV-seropositive recipients of an allogeneic hematopoietic stem-cell transplant (HSCT), who had undetectable plasma CMV DNA within five days of randomisation.

"The firm plans to submit regulatory applications based on the Phase III results for the approval of letermovir in the US and European Union (EU) this year."

The primary endpoint of the trial was the number of patients with clinically significant CMV infection through week 24 post-HSCT among patients with undetectable CMV DNA at the start of treatment.

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The firm plans to submit regulatory applications based on the Phase III results for the approval of letermovir in the US and European Union (EU) this year.

Letermovir has obtained orphan designation from the European Medicines Agency, the US Food and Drug Administration (FDA) and the Japanese Ministry of Health, Labour and Welfare for the prevention of CMV infection and disease in at-risk populations.

FDA has also granted the drug with fast-track designation.

Merck has purchased worldwide rights to develop and commercialise letermovir from AiCuris in 2012.

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