Safety and effectiveness of lisocabtagene maraleucel following PD-1 blockade in relapsed or refractory PMBCL.

Primary mediastinal B-cell lymphoma (PMBCL) is a distinct subtype of large B-cell lymphoma characterized by 9p24.1 copy-number alterations and PD-1-mediated immune evasion. This profile confers high sensitivity to PD-1 inhibitors such as pembrolizumab. CD19-directed chimeric antigen receptor (CAR) T-cell therapies have shown benefit in relapsed or refractory (R/R) PMBCL, but their optimal role remains undefined. We retrospectively analyzed 31 patients with R/R B-cell lymphoma treated with lisocabtagene maraleucel (liso-cel), including four with PMBCL who received pembrolizumab prior to CAR-T. All four achieved remission before infusion, and three maintained durable complete responses (≥ 30 months). Toxicities were comparable to those in patients not treated with pembrolizumab, although one pembrolizumab-treated patient experienced fatal neurotoxicity. Favorable hematologic recovery and preserved T-cell counts at leukapheresis suggest that preceding PD-1 blockade did not compromise CAR-T manufacturing and may have enhanced T-cell fitness. These findings suggest that sequential PD-1 blockade followed by liso-cel is clinically feasible and may improve outcomes by leveraging the immune vulnerability of PMBCL. While prior studies have focused on axicabtagene ciloleucel, this report provides the first real-world data supporting the feasibility and potential benefit of this approach with liso-cel. Prospective studies are needed to confirm efficacy, safety, and optimal sequencing.