Outcomes of Hematopoietic Cell Transplantation in Patients with Plasmablastic Lymphoma.

Plasmablastic lymphoma (PBL) is a rare and aggressive type of non-Hodgkin lymphoma with biological features that overlap between B-cell lymphoma and plasma cell neoplasm. There is currently no established standard treatment. However, intensive combination regimens, such as EPOCH, are recommended. There is a paucity of data regarding outcomes of hematopoietic cell transplantation (HCT) in this disease. Herein, we analyze data of patients with PBL who received autologous (autoHCT) or allogeneic (alloHCT) transplants using the Center for International Marrow and Transplant Research (CIBMTR) Registry. Between 2015 and 2024, a total of 186 and 31 patients underwent autoHCT and alloHCT, respectively, and met eligibility for the study. In the autoHCT group, 3-year overall survival (OS) was 75.5% (95% confidence interval [CI]: 68.3%-82.1%] and 3-year PFS was 60.6% (95% CI: 52.4%-68.5%], whereas 3-year NRM was 6.2% (95% CI: 2.9%-10.6%]. Outcomes of patients who received autoHCT after only 1 line of therapy were significantly better, with 3-year progression-free survival (PFS) at 74.7% (95% CI: 61%-85.7%] compared with 54% (95% CI: 39.9%-67.8%) in patients who received more than 1 line of therapy prior to transplantation (P = .046). In the alloHCT group, 3-year OS was 37.2% (95% CI: 19%-57.5%), 3-year PFS was 33.3% (95% CI: 16.3%-53.3%), and 3-year graft-versus-host disease-free/relapse-free survival was 20.8% (95% CI: 7.9%-37.8%), whereas 3-year nonrelapse mortality was 23.3% (95% CI: 8%-43.5%) and 3-year relapse risk was 43.3% (95% CI: 26%-61.6%). Relapse risk appears to plateau at approximately 1 year, suggesting the potential for curative outcomes in this disease. Overall, both autoHCT and alloHCT have demonstrated the potential to achieve prolonged survival in this aggressive lymphoma. However, early implementation of autoHCT following first-line therapy was associated with the most favorable outcomes.