Autologous stem cell transplantation in T-cell/histiocyte-rich large B-cell lymphoma: EBMT Lymphoma Working Party study.

Although broadly employed, consolidative autologous hematopoietic stem cell transplantation (autoHCT) for relapsed/refractory (r/r) T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL) has never been specifically investigated. Here we have analyzed outcomes of autoHCT for THRLBCL compared to diffuse large cell B-cell lymphoma not otherwise specified (DLBCL). Eligible for this retrospective registry study were adult patients with r/r THRLBCL and DLBCL, respectively, who underwent a first autoHCT in a salvage-sensitive disease status as assessed by PET-CT between 2016 and 2021 and were registered with the European Society for Blood and Marrow Transplantation (EBMT) database. Primary endpoint was progression-free survival (PFS) 2 years after transplantation. Two-hundred-one patients with THRLBCL and 5,543 with DLBCL were included. There were no significant differences in terms of disease status at HCT, pretreatment lines, and interval from diagnosis to transplant between the cohorts, but patients with THRBCL were significantly younger, contained a higher proportion of men, and had a better performance status. Compared to DLBCL, THRLBCL was associated with significantly better 2-year PFS (78% vs. 59%; p<0.001) and overall survival (OS; 81% vs. 74%; p=0.02) because of a significantly lower 2-year relapse incidence (RI; 16% vs. 35%; p<0.001). On multivariate analysis, favorable relapse risk (hazard ratio (HR) 0.46, 95%CI 0.31-0.7) and PFS (HR 0.58, 95%CI 0.41-0.82) of patients with THRLBCL remained significant, while OS benefits (HR 0.78, 95%CI 0.54-1.12) did not. These results were validated in a propensity-score matched analysis. These data prove autoHCT as an effective treatment option for salvage-sensitive r/r THRLBCL.