Favorable Outcomes from Allogeneic and Autologous Stem Cell Transplantation for Patients with Transformed Nonfollicular Indolent Lymphoma

The role of allogeneic (allo-) and autologous stem cell transplantation (auto-SCT) in the management of patients with transformed indolent nonfollicular non-Hodgkin lymphoma is unknown. This is a multicenter, retrospective cohort study of patients with biopsy-proven indolent B cell nonfollicular non-Hodgkin lymphoma and simultaneous or subsequent biopsy-proven aggressive histology transformation who were treated with allo-SCT or auto-SCT between 1996 and 2013. All patients received myeloablative conditioning regimens. Outcomes were compared with a cohort of 246 patients with transformed follicular lymphoma who also underwent allo-SCT (n = 47) or auto-SCT (n = 199) across the same institutions and time frame. Thirty-four patients were identified with the following underlying indolent histologies: 15 (44%) marginal zone lymphoma, 11 (32%) chronic lymphocytic leukemia, 6 (18%) small lymphocytic lymphoma, and 2 (6%) lymphoplasmacytic lymphoma. Patients received various anthracycline or platinum-containing chemotherapy regimens for transformation, incorporating rituximab in 25 (74%). Twelve (35%) subsequently underwent allo-SCT, whereas 33 (65%) underwent auto-SCT. The 3-year overall survival rate after transplantation was 67% (allo-SCT 54%, auto-SCT 74%), and 3-year progression-free survival rate was 49% (allo-SCT 40%, auto-SCT 54%). The 3-year nonrelapse mortality rate was 14% (allo-SCT 15%, auto-SCT 7%). Transplant-related mortality at 100 days was 17% for allo-SCT and 0% for auto-SCT. Adjusted for type of stem cell transplantation, 3-year overall survival, progression-free survival, and nonrelapse mortality rates were similar to those of patients with transformed follicular lymphoma receiving allo-SCT and auto-SCT (P = .38, P = .69, and P = .54, respectively). Allo-SCT and auto-SCT may be reasonable treatments for selected patients with transformed nonfollicular indolent lymphoma, although medium-term outcomes and toxicity appear to be more favorable with auto-SCT.