Clinical trial results presented at the American Society for Blood and Marrow Transplantation (ASBMT) 2017 BMT Tandem Meetings described the use of a novel agent, letermovir, to prevent cytomegalovirus (CMV) in patients undergoing hematopoietic stem cell transplantation. Cytomegalovirus infection is the most common viral infection in these patients after transplantation.1

A major challenge in finding an agent to protect patients against CMV infection is that many previously developed agents caused severe side effects.

This phase 3 clinical trial enrolled 565 adult patients from 67 research centers in 20 countries to investigate the efficacy of letermovir in the prevention of an active CMV infection after transplantation with donor stem cells.

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Patients underwent transplantation for hematologic malignancies or other disorders. All the participants were carriers of a dormant cytomegalovirus infection.

Within 24 weeks of completing up to 14 weeks of treatment, 61% of patients receiving a placebo developed active cytomegalovirus infection requiring treatment or discontinuation in the trial.

Only 38% of patients treated with letermovir developed serious cytomegalovirus infection or discontinued participation in the trial.

Patients receiving letermovir did not experience unacceptable adverse effects. Most toxicities were tolerable, such as mild nausea and vomiting and some swelling.

Patients receiving letermovir also experienced a survival benefit. At 24 weeks, 15% of patients in the placebo group had died, whereas 10% of patients in the letermovir group had died.

“For the first time, we seem to have a drug that is a true safe and effective preventive for CMV infection in stem cell transplant patients,” said Francisco Marty, MD, an infectious disease specialist at Dana-Farber and Brigham and Women’s Hospital, Boston, Massachusetts, and an investigator in the study.

“Letermovir will allow many patients to avoid infection, usually with no or mild side effects, and seems to provide a survival benefit in the first 6 months posttransplant.”

Reactivation of cytomegalovirus has remained a major obstacle after hematopoietic stem cell transplantation.

“The goal was to suppress the virus before it has a chance to become active,” Marty explained.


1. Dana-Farber Cancer Institute. New antiviral drug cuts cytomegalovirus infection and improves survival in patients [news release]. EurekAlert web site. Published February 24, 2017. Accessed March 1, 2017.