Kidney transplant recipients who received letermovir (Prevymis, Merck) for cytomegalovirus (CMV) prophylaxis experienced similar virologic protection but significantly less myelosuppression compared with those treated with valganciclovir (Valcyte, Roche), according to an abstract (P-2108) presented at IDWeek 2025, in Atlanta.
The study, presented by Ismael Aguirre, PharmD, a pharmacy resident at Oregon Health & Science University (OHSU), in Portland, compared real-world outcomes for the two antiviral agents following the 2023 FDA approval of letermovir for CMV prophylaxis in high-risk kidney transplant recipients. “CMV threatens immunocompromised patients, especially solid organ transplant recipients,” Dr. Aguirre and colleagues wrote. “Prophylaxis with valganciclovir or ganciclovir is standard but causes hematologic toxicity. Letermovir showed similar efficacy with fewer side effects.”
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Letermovir Versus Valganciclovir
In the single-center, retrospective chart review, investigators evaluated adult kidney transplant recipients at OHSU who received either letermovir or valganciclovir between June 2022 and December 2024. Patients were excluded if they were pediatric or pregnant, as well as if they received treatment through the Veterans Affairs health system, died within six months post-transplant, or did not complete prophylaxis. Clinical data were drawn from electronic medical records and the United Network for Organ Sharing database.
The primary end point was breakthrough CMV viremia within six months of transplantation. Secondary outcomes included safety and tolerance measures such as leukopenia and neutropenia rates.
Among 62 patients included, 21 received letermovir; 41, valganciclovir. Breakthrough CMV viremia occurred in 4.8% (1/21) of letermovir patients versus 14.6% (6/41) of those receiving valganciclovir. No patients in either group were hospitalized for CMV-related complications.
Hematologic adverse effects differed markedly between groups, with a major benefit seen in the letermovir arm. Leukopenia occurred in 24% of letermovir recipients versus 57% in the valganciclovir arm (P=0.006), while neutropenia was seen in 39% versus 61%, respectively (P=0.015).
“Findings from this study are consistent with prior clinical trials demonstrating the noninferiority of letermovir for CMV prophylaxis in kidney transplant recipients,” concluded the authors, led by OHSU PGY-2 pharmacy resident YoungYoon Ham, PharmD, and Ali Olyaei, PharmD, a professor of pharmacy at Oregon State University College of Pharmacy and professor of medicine and surgery at OHSU School of Medicine. “Letermovir showed reduced myelosuppression including leukopenia and neutropenia.”
Prophylaxis With Fewer Side Effects
Although the study was retrospective and limited by its small sample size, the findings align with growing evidence that letermovir provides effective prophylaxis with fewer hematologic complications, a key advantage for transplant programs aiming to avoid dose interruptions or granulocyte-stimulating factor use.
Letermovir, a CMV terminase complex inhibitor originally approved for hematopoietic stem cell transplant recipients, received FDA approval in 2023 for CMV prophylaxis in high-risk kidney transplant patients. The approval was based on a phase 3 trial showing noninferiority to valganciclovir for prevention of CMV disease and a markedly lower incidence of leukopenia and neutropenia (JAMA 2023;330[1]:33-42). The new data reinforce the trial results in real-world practice.
The sources reported no relevant financial disclosures.