B375 - Outcomes of Conversion from Valganciclovir to Letermovir for Cytomegalovirus Prophylaxis in Abdominal Transplant Recipients

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Author Block: L. McCord¹, E. Graves¹, B. Summers¹, A. Gerlach¹, T. Pesavento², N. Marschalk¹, A. Nolan¹, ¹The Ohio State University Wexner Medical Center, Columbus, OH, ²Ohio State University, Columbus, OH
*Purpose: The purpose of this study was to evaluate antimetabolite dosing, leukopenia rate, and granulocyte colony stimulating factor (GCSF) use in abdominal transplant recipients converted to letermovir (LET) from valganciclovir (VGCV) for cytomegalovirus (CMV) prophylaxis.
*Methods: This was a single-center, retrospective cohort study evaluating adult abdominal transplant recipients at intermediate and high-risk for CMV. Patients converted from VGCV to LET within one year from most recent kidney, liver, or pancreas transplant between 1/1/21- 1/1/24 were included. Patients were excluded if prescribed LET for less than two weeks, initiated for secondary prophylaxis, or had a CMV PCR greater than 1,000 IU/mL at time of initiation. Leukopenia was defined as white blood cell count (WBC) of < 3 Kcells/µliter Statistical analysis of nominal data was analyzed using Fischer’s exact test and presented as n (%). Continuous data was presented as median [25-75% IQR] and analyzed with Mann-Whitney U tests.
*Results: LET was initiated for leukopenia in 67 abdominal transplant patients, 56 (83.6%) high-risk and 11 (16.4%) moderate-risk, at a median of 71 days [48-94] post-transplant. At 30 days after LET initiation, the median WBC increased significantly (4.69 [3.40-6.20 Kcells/µliter p<0.001) with 11 (16.4%) patients having leukopenia. At the end of LET (median 44 [18.8-77] days), WBC was also significantly higher (5.17 [3.56-6.4] Kcells/µliter p<0.001) and no patients were leukopenic. Twenty (29.9%) patients required GCSF administration prior to switching to LET versus 4 (6%) afterwards, p=0.0005. At the end of LET, 12 (22.2%) patients were restarted on MMF and 10 (18.5%) had MMF dose increase. Three (14.3%) patients had breakthrough CMV while on LET requiring treatment. There were no significant differences found in rates of rejection, allograft loss, infection, or mortality.
*Conclusions: Overall, patients converted to LET for CMV prophylaxis had an increase in median WBC, less GCSF use, and an increase in antimetabolite dosing. This supports use of LET conversion in leukopenic abdominal transplant patients, allowing for optimization of immunosuppression.