Maribavir use in practice for cytomegalovirus infection in French transplantation centers.

Maribavir (MBV), a UL97 inhibitor, shows good oral bioavailability, low host cell toxicity, and theoretical benefits to inhibit cross-resistant viruses. We herein examined clinical and virological outcomes of 12 patients, including 3 bone marrow recipients and 9 organ recipients infected with resistant cytomegalovirus (CMV) and treated with MBV during 2011-2012. All received at least 800-mg daily doses. They had developed clinical (12/12) and/or virological (11/12) resistance to CMV infection. Based on a decrease of viral load in blood >1.5 log copies/mL half of them responded to MBV treatment. The individual changes varied from a rapid decrease in viral load (n = 4) to no response (n = 3) with some late response slowly decreasing viremia (n = 3). In 2 cases MBV was used as secondary prophylaxis. No clear parameter emerged as a clinical surrogate for nonresponse to MBV. These results contrast with the lack of efficacy in phase III trials of MBV prophylaxis among stem cell recipients, which were possibly due to low doses or inadequate timing of drug initiation in the study. Additional clinical and surrogate laboratory markers are needed to determine antiviral responses to guide MBV use. Dosage ranging studies might benefit future MBV use.