Role of hematopoietic stem cell transplantation for advanced-stage diffuse large cell B-cell lymphoma-B.

The prognosis of patients with relapsed or refractory diffuse large cell B-cell lymphoma-B (DLCL-B) is poor with conventional salvage chemotherapy; therefore, high-dose therapy (HDT) combined with autologous stem cell transplant (ASCT) has become the treatment of choice for these patients. The outcomes of transplant are better in patients with chemosensitive relapse: those with a longer duration of first remission (>12 month) and those with an age-adjusted low-risk International Prognostic Index (IPI) at relapse. Several high-dose regimens with or without total body irradiation (TBI) have been used with similar outcomes. Relapse remains the most common cause of treatment failure, and thus the use of radioimmunotherapy (RIT) in the high-dose regimens and incorporation of rituximab in the transplant setting have been explored. Several studies have shown that RIT both at conventional dose and at high dose can be given in combination with high-dose chemotherapy regimens without additional toxicity or delay in hematopoietic recovery after ASCT. Additional studies using RIT in combination with high-dose chemotherapy and ASCT are ongoing, and preliminary results suggest that these approaches may be superior to conventional high-dose regimens. Since rituximab is an effective therapy for B-cell non-Hodgkin's lymphoma and given its limited toxicity, rituximab has been incorporated into HDT and ASCT for DLCL-B as in vivo purging, as part of high-dose regimens, and as maintenance therapy to prevent relapse. Preliminary results suggested that rituximab during ASCT and as maintenance therapy post-transplant reduces the risk of relapse and improves survival; however, these results need to be confirmed in phase III randomized trials. The role of ASCT during first remission as consolidative therapy in patients with DLCL-B remains controversial and should not be performed outside of the clinical trial setting. Allogeneic stem cell transplant (allo-SCT) for patients with relapsed DLCL-B is associated with significant toxicity and should be reserved for patients who relapse after ASCT or those with persistent marrow involvement. Innovative approaches are needed for primary refractory and chemoresistant relapsed DLCL-B since these patients have very poor outcomes after ASCT.