Richter syndrome (RS) represents a transformation from chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) to an aggressive lymphoma, most commonly diffuse large B-cell lymphoma (DLBCL), associated with a dismal prognosis. Patients with DLBCL-RS have poor outcomes with DLBCL-directed therapy, thus consolidation with hematopoietic cell transplantation (HCT) has been used with durable remissions observed. Studies reporting HCT outcomes in patients with DLBCL-RS have been small, have not evaluated the prognostic impact of cytogenetic risk factors, and were conducted prior to the era of novel, targeted therapy of CLL/SLL. We performed a CIBMTR registry study evaluating outcomes after autologous (auto, n=53) and allogeneic (allo, n=118) HCT in patients with DLBCL-RS treated in the modern era. More auto-HCT recipients were in complete response at HCT relative to allo-HCT recipients (66% versus 34%), while a higher proportion of allo-HCT recipients had 17p deletion (33% versus 7%) and had previously received novel agents (39% versus 10%). In the auto-HCT cohort, the 3-year relapse incidence, progression-free survival (PFS), and overall survival (OS) were 37%, 48%, and 57%, respectively. Among allo-HCT recipients, the 3-year relapse incidence, PFS, and OS were 30%, 43%, and 52%, respectively. In the allo-HCT cohort, deeper response at HCT was associated with outcomes (3y PFS/OS: 66%/77% CR versus 43%/57% PR versus 5%/15% resistant, p<.0001 for both), while cytogenetic abnormalities and prior novel therapy did not impact outcomes. In our study, HCT resulted in durable remissions in therapy-sensitive patients with DLBCL-RS treated in the era of targeted CLL/SLL therapy, including patients with high-risk features.
