Reduced-Intensity Conditioning (RIC) Followed by Allogeneic Transplantation in Relapsed Lymphomas: Evidence for Graft-Versus-Lymphoma Effect in Low and High Grade Histologies, but Not in Hodgkin Disease.

Reduced intensity conditioning (RIC) followed by allogeneic stem cell transplantation (SCT) is associated with durable engraftment, low transplant-related mortality (TRM) and clinical remissions in hematologic malignancies. In addition, RIC followed by allograft is feasible also in patients who had failed previous autologous (auto) SCT. Here, we report the outcome of 118 lymphoma pts receiving RIC and allogeneic SCT from HLA-identical sibling donors. Histologic types included in the study were: chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL; n=26), low-grade non-Hodgkin lymphoma (LG-NHL; n=24, 21 follicular NHL), high-grade NHL (HG-NHL, B cell n=28, T cell n=17), Hodgkin disease (HD; n=23). Median age was 50 years (range: 20–69). 47% of pts had refractory disease (46% CLL/SLL; 33% LG-NHL; 44% HG-NHL; 56% HD) and 48% have failed an auto SCT (15% CLL/SLL; 33% LG-NHL; 55% HG-NHL; 82% HD). All pts received debulkying chemotherapy followed by the same RIC regimen with thiotepa (10 mg/kg), fludarabine (60 mg/ms) and cyclophosphamide (60 mg/kg). GVHD prophylaxis consisted of cyclosporine A and short-course methotrexate. All pts engrafted. De-novo acute GVHD developed in 43% of pts and chronic GVHD in 45%. The 2-year TRM rate was 13% and was not influenced by previous auto SCT or hystological type. At a median follow-up of 20 months (range, 6–62 months), 91 pts (77%) are alive (n=69 CR, n=8 PR, n=14 with disease) and 27 died (23%) for disease (n=17) or TRM (n=10). The 2 years PFS rates for CLL/SLL, LG-NHL, HG-NHL, HD were 63%, 78%, 64%, 16%, respectively. Chemorefractory disease at time of SCT was associated with a worse 2-year PFS compared to chemosensitive disease (41% versus 74%, p<0.001). There was a trend toward lower relapse risk for pts developing acute or chronic GVHD (37% versus 50%, p=0.2). The 2-year OS rates for CLL/SLL, LG-NHL, HG-NHL, HD were 77%, 90%, 76%, 56%, respectively. Chemosensitive disease had significant impact on OS (84% 2-year OS compared with 64% for chemorefractory patients; p< 0.007) as well the occurrence of chronic GVHD (87% versus 57%; p<0.0059). Interestingly, previous auto SCT and age > 55 years did not influence OS. Among pts in clinical CR, 24 were suitable for PCR monitoring of residual disease and 17 pts (71%) are in continuous molecular remission. Our study indicates: 1) low TRM in a multicenter phase II study; 2) low risk of relapse and good survival rates in indolent lymphomas; 3) encouraging results in HG-NHL 4) disappointing results in HD