Letermovir Conversion for Cytomegalovirus Prophylaxis in Solid Organ Transplant

Cytomegalovirus (CMV) is a common opportunistic infection post-solid organ transplant; however, traditional prophylaxis agents have been associated with myelosuppression, limiting their use. Letermovir (LTV) is an antiviral approved for use in kidney transplantation, and often used off-label in non-renal transplant patients; however, little data exist on cell count recovery and time to recovery in the non-renal and multi-organ transplant population.

This was a single-center, retrospective, descriptive cohort study at a large academic medical center assessing conversion to LTV from (val)ganciclovir for primary CMV prophylaxis. Outcomes included change in white blood cell (WBC) count from immediately prior to LTV conversion to 30 days post-initiation, indications for switching to LTV, and rates of breakthrough CMV infection.

Fifty-eight patients transplanted between January 1, 2017, and December 31, 2023, were included in this cohort, with the majority being lung transplant recipients (57%). Median increase in WBC was + 2.07 k/µL (IQR 3.95-8.21; p < 0.01) from time of LTV initiation to 30 days following conversion. The most common indication for LTV was pancytopenia in 26 patients (45%). Breakthrough CMV infections occurred in four patients (7%), all of which were viremia, and did not exhibit resistance against CMV active agents. There was an observed increase in mycophenolate use and tolerance and a decrease in granulocyte-colony stimulating factor (G-CSF) over the study period.

LTV was effective and well-tolerated for primary CMV prophylaxis in an extra-renal transplant population and may be a safe alternative in patients experiencing sustained hematologic toxicities with (val)ganciclovir across all transplant groups.