The Food and Drug Administration on Nov. 8 approved the use of letermovir (Prevymis) tablets and injections for the prevention of cytomegalovirus (CMV) infection and disease in adults exposed to the virus who have received an allogeneic hematopoietic stem cell transplant (HSCT). This is the first drug to be approved for this purpose. It had previously been granted Breakthrough Therapy and Orphan Drug designation.

CMV infection is a major risk for patients undergoing HSCT, because an estimated 65%-80% of these patients already have been exposed to the virus.

The approval comes on the basis of a phase 3 randomized controlled trial showing that letermovir was superior to placebo at preventing CMV infection through 24 weeks after transplant. According to a press release from Merck, the maker of letermovir, 38% of the letermovir group (122/325) and 61%, (103/170) of the placebo group developed clinically significant CMV infections, discontinued treatment, or had missing data through week 24. The 23.5% difference between the two groups was statistically significant (95% confidence interval, 32.5-14.6; P less than .0001).

Side effects associated with the use of letermovir include nausea, diarrhea, vomiting, swelling in the arms and legs, cough, headache, tiredness, and abdominal pain. The drug is contraindicated for patients receiving pimozide and ergot alkaloids, or pitavastatin or simvastatin when coadministered with cyclosporine. Prescribing information is available at the FDA website.