Reduced-intensity conditioning for allogeneic haematopoietic stem cell transplantation in relapsed and refractory Hodgkin lymphoma: impact of alemtuzumab and donor lymphocyte infusions on long-term outcomes

The introduction of reduced-intensity conditioning (RIC) has enabled the role of allogeneic transplantation to be re-evaluated in Hodgkin lymphoma (HL). While T-cell depletion reduces graft-versus-host disease (GvHD), it potentially abrogates graft-versus-tumour activity and increases infective complications. We compared the results in 67 sibling donor transplantations following RIC in multiply relapsed patients from two national phase II studies conditioned with fludarabine/melphalan. One used cyclosporine/alemtuzumab (MF-A, n = 31), the other used cyclosporine/methotrexate (MF, n = 36) as GvHD prophylaxis. There was a small excess of chemorefractory cases in the MF cohort (P = NS). MF-A resulted in significantly lower incidences of non-relapse mortality, acute and chronic GvHD, but no significant excess of relapse/progression. Post donor lymphocyte infusion (DLI) disease responses occurred in 8/14 (57%) and 6/11 (55%) patients in the MF-A and MF groups, respectively. Current progression-free survival (CPFS) was superior with MF-A (univariate analysis), with durable responses to DLI contributing to the favourable outcome (43% vs. 25%, P = 0.0356). Disease status at transplantation significantly influenced overall survival (P = 0.0038) and CPFS (P = 0.0014), retaining significance in multivariate analyses, which demonstrated a trend towards improved CPFS with T-cell depletion (P = 0.0939). These data suggest that alemtuzumab significantly reduced GvHD without resulting in a deleterious impact on survival outcomes following RIC in HL, and that durable responses to DLI may be more common following the inclusion of alemtuzumab in the conditioning protocol.