Cytomegalovirus prophylaxis using low-dose and ultra-low-dose valganciclovir for patients who have undergone allogeneic hematopoietic stem cell transplantation: A retrospective study

Objective Cytomegalovirus reactivation is a clinically significant complication after allogeneic hematopoietic stem cell transplantation. Valganciclovir is commonly used for cytomegalovirus prophylaxis; however, the optimal dosing strategy remains unclear. This study compared the efficacy and safety of ultra-low-dose valganciclovir (450 mg every other day) and low-dose valganciclovir (450 mg daily) in preventing cytomegalovirus reactivation after allogeneic hematopoietic stem cell transplantation. Methods We retrospectively reviewed adult patients who underwent allogeneic hematopoietic stem cell transplantation from January 2020 to December 2023. Individuals receiving low-dose (n = 31) or ultra-low-dose (n = 35) valganciclovir as cytomegalovirus prophylaxis were included. Cytomegalovirus DNAemia was evaluated within the first 14 weeks and then at 14–28 weeks after transplantation. Cytomegalovirus disease, acute graft-versus-host disease, survival outcomes, and hematologic toxicities were also assessed. Results The prevalence of early cytomegalovirus reactivation was 13.8% in the low-dose group and 20.0% in the ultra-low-dose group ( p = 0.301). Late reactivation rates were similarly low in the low-dose and ultra-low-dose groups (3.6% vs. 6.2%, p = 1.000). Hematologic adverse events were comparable; however, treatment discontinuation due to cytopenia was significantly more common with low-dose therapy (48.4% vs. 17.1%, p = 0.007). Overall survival (80.6% vs. 75.8%, p = 0.839) and acute graft-versus-host disease (29.1% vs. 45.7%, p = 0.381) rates did not exhibit statistically significant differences between the two groups. Conclusions Ultra-low-dose valganciclovir demonstrated better tolerability but may provide less protection against cytomegalovirus reactivation.