Consolidative allogeneic stem cell transplantation following bispecific antibody salvage in relapsed/refractory high-grade B-cell lymphoma: representative cases and literature review

High-grade B-cell lymphomas (HGBCL), which include double/triple-hit lymphomas with MYC and BCL2 and/or BCL6 rearrangements and HGBCL, not otherwise specified (NOS), are aggressive non-Hodgkin lymphomas with a poor prognosis. In high-risk patients, complete response rates after frontline therapy are only 50–60%, and early relapse occurs in 30–40% of cases. Outcomes in the relapsed/refractory (R/R) setting remain poor, even with modern T-cell–engaging therapies. Bispecific antibodies (BsAb) have emerged as a promising off-the-shelf option, with activity in chemorefractory disease and the ability to induce deep metabolic responses, including in patients who have relapsed after chimeric antigen receptor T-cell (CAR-T) therapy or are ineligible for it. However, the aggressive biology of HGBCL raises concerns about the durability of BsAb-induced remissions without consolidation, and therefore about whether patients achieving a complete metabolic response (CMR) should be considered for allogeneic haematopoietic stem cell transplantation (allo-HSCT). Allo-HSCT is a potentially curative strategy for fit patients with R/R lymphoma, mediated by graft-versus-lymphoma (GVL) effects, but it carries a risk of substantial treatment-related morbidity, particularly graft-versus-host disease (GVHD). Evidence on allo-HSCT after BsAb exposure is scarce. Available data suggest that this sequential approach is feasible and safe. Here, we report two cases of R/R HGBCL that achieved sustained remission after glofitamab-based therapy followed by consolidative allo-HSCT, with manageable toxicity. These cases add to the emerging real-world evidence for this strategy in fit patients with R/R HGBCL who attain CMR after BsAb therapy.