Efficacy of Allogeneic Stem-Cell Transplantation for T/NK-Cell Lymphomas in Adults.

Mature peripheral T/Natural killer (NK)-cell neoplasms represent 10–15% of non-Hodgkin’s lymphoma (NHL) in adults. T/NK-NHL have a worst prognosis compared with B-cell lymphomas. Allogeneic stem cell transplantation (allo-SCT) is an attractive option for these patients. On behalf of the SFGM-TC group, we conducted a retrospective analysis and included seventy-seven T/NK-cell lymphoma patients. Diagnosis were: ALCL (n=27), Peripheral T-cell Lymphoma Not-Otherwise Specified (PTCL-NOS) (n=27), Angioimmunoblastic T-cell Lymphoma (AITL) (n= 11), Hepatosplenic g/d lymphoma (HSL) (n=3), T-cell granular lymphocytic leukemia (T-GLL) (n=1), nasal NK/T-cell lymphoma (nasal-NK/L) (n=3) case or non-nasal NK/T-cell lymphoma (non nasal-NK/L) (n=2), enteropathy-Type T-cell (n=1) and HTLV-1 lymphoma (n=2). Fifty-seven patients received myeloablative conditioning regimen prior allo-SCT. Donors were HLA-matched in 70 cases and related in 60 cases. Patients status at the time of allo-SCT was CR in 31 cases, PR in 26 cases and SD/PD in other cases. Five-year toxicity-related mortality (TRM) rate was 34%. Major cause of death was infection. Five-year OS and EFS rates were 57% and 53.3%, respectively. In a multivariate analysis, chemoresistance disease (SD, refractory or progressing disease at the time of allo-SCT and aGVHD grade III/IV were the only adverse prognostic factors for OS (p= 0.027 and p=0.033, respectively). Disease status at transplantation influenced EFS (p= 0.0032) and a HLA-mismatched donor increased TRM (p= 0.0386). A plateau was reached after one and a half year after allo-SCT. Only 5 out of 59 patients in CR after allo-SCT experienced a relapse. The 5-year OS rate for chemo-resistant patients was also encouraging. These patients were not curable with conventional approaches and near of one third have taken advantage of allo-SCT. Furthermore, two patients received DLI at relapse and they both reached a second durable CR. Taken together, this suggests that there is a graft versus T-/NK-lymphoma effect which may play a role in the curative potential of allo-SCT. we conclude that randomized clinical trials comparing allo-SCT versus conventional chemotherapy upfront for PTCL, aggressive AITL or histopathological subtypes (HSL, HTLV-1 lymphomas) have to be encouraged.