Allogeneic transplantation following a reduced-intensity conditioning regimen in relapsed/refractory peripheral T-cell lymphomas: long-term remissions and response to donor lymphocyte infusions support the role of a graft-versus-lymphoma effect

Rescue chemotherapy or autologous stem cell transplantation (autoSCT) gives disappointing results in relapsed peripheral T-cell lymphomas (PTCLs). We have retrospectively evaluated the long-term outcome of 52 patients receiving allogeneic SCT for relapsed disease. Histologies were PTCL-not-otherwise specified (n=23), anaplastic large-cell lymphoma (n=11), angioimmunoblastic T-cell lymphomas (n=9) and rare subtypes (n=9). Patients were allografted from related siblings (n=33, 64%) or alternative donors (n=13 (25%) from unrelated and 6 (11%) from haploidentical family donors), following reduced-intensity conditioning (RIC) regimens including thiotepa, fludarabine and cyclophosphamide. Most of the patients had chemosensitive disease (n=39, 75%) and 27 (52%) failed a previous autoSCT. At a median follow-up of 67 months, 27 of 52 patients were found to be alive (52%) and 25 (48%) were dead (n=19 disease progression, n=6 non-relapse mortality (NRM)). The cumulative incidence (CI) of NRM was 12% at 5 years. Extensive chronic graft-versus-host disease increased the risk of NRM (33% versus 8%, P=0.04). The CI of relapse was 49% at 5 years, influenced by disease status at the time of allografting (P=0.0009) and treatment lines (P=0.007). Five-year overall survival and progression-free survival (PFS) were 50% (95% CI, 36 - 63%) and 40% (95% CI, 27 - 53%), respectively. The current PFS was 44% (95% CI, 30-57%). In all, 8 out of 12 patients (66%) who received donor-lymphocytes infusions for disease progression had a response. At multivariable analysis, refractory disease and age over 45 years were independent adverse prognostic factors. RIC allogeneic SCT is an effective salvage treatment with a better outcome for younger patients with chemosensitive disease.