Greatly reduced risk of EBV reactivation in Rituximab-experienced recipients of Alemtuzumab-conditioned allogeneic HSCT

Epstein-Barr virus (EBV)-associated post-transplant lymphoproliferative disease (PTLD) remains an important complication of allogeneic haematopoietic stem cell transplantation (allo-HSCT). We retrospectively analysed incidence and risk factors for EBV reactivation in 196 patients undergoing consecutive allo-HSCT with T-cell depletion (TCD). Amongst 186 patients who received Alemtuzumab TCD, the cumulative incidence of EBV reactivation was 48% (CI 41 - 55%) by one year. High-level EBV reactivation occurred in 18% (CI 13 – 24%), and 8 patients were concurrently diagnosed with PTLD. Amongst 10 patients who received anti-thymocyte globulin (ATG), 3 developed PTLD. In univariate analysis, significant risk factors for EBV reactivation included age ≥50 years (HR 1.57; p=0.024) and ATG versus Alemtuzumab (HR 4.6; p<0.0001). Importantly, a diagnosis of non-Hodgkin lymphoma (NHL) was associated with a highly significant reduction in the risk of EBV reactivation (HR 0.1; p=0.0001), confirmed in multivariate testing. Rituximab therapy within 6 months prior to allo-HSCT was highly predictive for lack of EBV reactivation (HR 0.17; p=0.0005), although confounding with NHL was apparent. Our data emphasise the risk of PTLD associated with Alemtuzumab TCD. Furthermore, we report a novel and clinically important observation indicating that Rituximab, administered in the peri-transplant period, may provide effective prophylaxis for PTLD.