1601. Effect of Preemptive Rituximab Therapy on Epstein–Barr Reactivation in Allogenic Hematopoietic Stem Cell Pediatric Transplants

Abstract

BackgroundChildren with Epstein–Barr virus (EBV) viremia after hematopoietic stem cell transplantation (HSCT) are at increased risk of post-transplant lymphoproliferative disease (PTLD). Our aim was to assess whether pre-emptive rituximab reduced EBV-viral load (EBV-VL) and the risk of developing PTLD.MethodsWe retrospectively included all children who had a positive EBV-VL within 12 months after an allogenic HSCT (2007–2015) in a single tertiary pediatric hospital. Whole blood EBV-VL was monitored weekly using a real-time PCR, during the first 100 days after HSCT and then monthly until 6 months post-HSCT or until EBV-VL became undetectable. EBV-VL clearance was defined as two negative EBV-VL at least 1 week apart. Pre-emptive rituximab was defined as a treatment administered before the occurrence of PTLD. We determined the impact of pre-emptive rituximab on EBV-VL clearance, using a marginal structural cox model, adjusting for age at transplant, time between transplant and first positive EBV-VL, in-vivo T-cell depletion at induction, value of EBV-VL at the first dose of rituximab, and the EBV-VL value at the current and previous time point.ResultsOf 214 children who underwent allogenic HSCT, EBV DNA was detected in 87 (41%) children. Children who received rituximab after diagnosis of PTLD were excluded, leading to a cohort of 78 children. Twenty-two (28%) children received pre-emptive rituximab. Mean (SD) age was similar in both groups (10 [5] year). First post-transplant positive EBV-VL was earlier in the pre-emptive rituximab group (mean of 55 [54] vs. 113 [96] days; P < 0.05) and first positive EBV-VL was higher in the pre-emptive rituximab group (mean of 3.4 [0.6] vs. 3.0 [0.6] log10/mL; P < 0.05). In adjusted analyses, pre-emptive rituximab was associated with a higher likelihood of EBV-VL clearance (hazard ratio 1.86; 95% confidence interval 1.10–3.14; Figure 1). Of the 10 children who developed PTLD, none had received pre-emptive rituximab.ConclusionEBV viremia is frequent in children with allogenic HSCT. Our results suggest that pre-emptive rituximab is associated with more rapid EBV-VL clearance. The effect of rituximab on the risk of PTLD needs to be better defined.Figure 1.Inverse probability of EBV viremia clearance in children.Disclosures All authors: No reported disclosures.