Role of bridging RT in relapsed/refractory diffuse large B-cell lymphoma undergoing CAR-T therapy: a multicenter study

The optimization of bridging regimen before chimeric antigen receptor (CAR)-T cell therapy in diffuse large B-cell lymphoma (DLBCL) may impact CAR-T efficacy and outcome. This retrospective study evaluates CAR-T outcome after bridging with radiotherapy (RT) and other bridging strategies. Among 148 patients with relapsed/refractory DLBCL who underwent leukapheresis for CAR-T manufacturing, 31 received RT-bridging, 84 chemotherapy (CT), 33 no-bridging or steroid-only. CAR-T cell were infused in 96.8% of RT-group. 89.2% of CT-group and 78.8% of no-bridge group (p = 0.079). Response to bridging was generally poor, but patients receiving RT had a significant reduction in LDH levels between pre- and post-bridging (p = 0.05). The one-year PFS was 51.2% in the RT group, 28.2% in the CT group, and 47.6% in the no-bridge group (p = 0.044); 1-year OS was 86.7% in the RT group, 52.7% in the CT group and 69% in the no-bridge group (p = 0.025). We observed a higher incidence of ICANS in patients who received CT than in others (20.0% CT group, 3.3% RT group, 7.7% no-bridge group; p = 0.05). In conclusion, RT-bridging is associated with lower drop-out rate and CAR-T toxicity, and it might be preferred to other bridging strategies for patients with localized disease or for those with one prevalent symptomatic site.