Allogeneic Stem Cell Transplantation Results in a Low Relapse Rate in Patients with Peripheral T-Cell Lymphoma.

Patients (pts) suffering from mature (peripheral) T-cell lymphoma are known to have a poor outcome compared to pts with aggressive B-cell lymphoma when receiving conventional therapies. However, case reports and single centre experiences show promising results of allogeneic stem cell transplantation (allo SCT) for these pts. We here present a retrospective analysis of 103 pts with mature T-cell lymphoma who received an HLA-identical allo SCT in EBMT centres between 2000 and 2005. Histological subtypes of the patients were anaplastic large cell lymphoma (n=25; 4 anaplastic lymphoma kinase [ALK] positive, 11 ALK negative, 10 ALK unknown), peripheral T-cell lymphoma unspecified (n=51), angioimmunoblastic T-cell lymphoma (n=18) and aggressive T-cell lymphoma unspecified (n=9). Patients with primary cutaneous T-cell lymphoma or T-lymphoblastic lymphoma were excluded. Median follow up for surviving patients was 40 months (6–98), median age at allo SCT 42 years (18–68) and median time to allo SCT 17 months (3–233). 39 pts had failed a prior autologous SCT; 68 pts had chemosensitive disease at allo SCT (of these 15 in CR1) and 30 pts had chemorefractory or untested relapsed or progressive disease. Donors were HLA identical siblings for 73 and matched unrelated donors for 30 pts; 82 pts received peripheral blood stem cells. 54 pts were treated with reduced intensity conditioning before SCT. The cumulative incidence (CI) of acute graft versus host disease (GvHD) 100 days after SCT was 52% and had no effect on non-relapse mortality (NRM) or relapse rate (RR). 34 of 74 evaluable pts experienced chronic GvHD (14 limited, 20 extensive), CI 46% at 2 years. Introducing chronic GvHD as a time dependent covariate, this factor was associated with a higher NRM (p<0.001) and a lower RR (statistically not significant), resulting in a lower progression free survival (PFS) (p=0.001). For all patients CI of NRM and RR at 3 years were 36.7% and 24.9%, respectively, resulting in 41.4% PFS and 46.9% OS. Median time to relapse / progression was 4 (1–18) months. In multivariate COX analysis for PFS refractory disease (relative risk 3.4, p=0.001), prior failed auto SCT (relative risk 2.6, p=0.001) and poor performance status at SCT (relative risk 2.5, p=0.04) were significant adverse factors. Additionally, there were trends for T-cell depleted grafts (p=0.1), CMV status other than negative-negative (p=0.1) and reduced intensity conditioning (p=0.2) to be adverse factors. A subgroup of 39 good risk pts (good performance status, chemosensitive disease, no prior autologous SCT) had a PFS of 59%.

This retrospective analysis on allo SCT in peripheral T-cell lymphoma shows an encouraging low RR but efforts have to be made to reduce NRM. Prospective studies are warranted to further define pts who will profit from an early allo SCT.