Efficacy of Low-Dose Rituximab as Preemptive Treatment of EBV DNA-emia After Allogeneic Hematopoietic Stem Cell Transplantation.

Epstein-Barr virus (EBV) reactivation is a common complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT), particularly in patients receiving high-dose anti-thymocyte globulin (ATG)-containing conditioning regimens. If left untreated, EBV reactivation may progress to post-transplant lymphoproliferative disorder (PTLD), a life-threatening condition. While preemptive therapy with the standard dose of rituximab (RTX), 375 mg/m², is recommended for EBV-related complications, such a high dose may be unnecessary in post-transplant settings where the total lymphocyte mass is significantly reduced compared to lymphoma conditions. This retrospective study assessed the efficacy and safety of fixed low-dose RTX (100-200 mg per dose) as an exploratory dose de-escalation preemptive therapy for low-load EBV DNA-emia (<10,000 copies/mL) occurring within four months post-transplantation. Among 83 high-risk patients, RTX achieved a high EBV clearance rate of 93.9% (95% CI: 88.6%-99.2%), with comparable effectiveness observed between the 100 mg and 200 mg dosage groups. Viral clearance was rapid, with most patients becoming EBV-DNA negative after 1 to 2 doses. RTX was well tolerated, with no treatment discontinuations due to adverse events. Despite preemptive RTX, four patients (5%) developed PTLD, which aligns with previously reported rates in similar populations. At a median follow-up of 41.6 months, the 3-year overall survival (OS) rate was 67.7%, with no significant differences in OS, relapse, or nonrelapse mortality between the two dosage cohorts. These findings suggest that a fixed low-dose RTX regimen, as an exploratory dose de-escalation strategy, is safe, effective, and well-tolerated for the preemptive management of low-load EBV DNA-emia in allo-HSCT recipients. While these results are hypothesis-generating, they indicate rapid viral clearance and favorable long-term outcomes, warranting further validation in comparative studies.