To compare the efficacy and safety of radiotherapy before and after anti-CD19-CAR T-cell therapy in patients withrelapsed/refractory DLBCL

Background: What is the difference in efficacy and side effects of radiotherapy bridging CAR-T therapy versus CAR-T therapy followed by radiotherapy? Patients and methods Fourteen R/R DLBCL patients received radiotherapy before CAR-T therapy (R-C group). R-C group was divided into: 1-3 months radiotherapy before CAR-T therapy (1-3 mons) group and more than 3 months before CAR-T therapy (more than 3 mons) group. Seventeen patients received radiotherapy 2-3 months after CAR-T therapy (C-R) group. Results: In R-C group, ORR was 81.82% and CR was 54.55%. In C-R group, ORR was 64.71% and CR was only 35.29% after CAR-T therapy, but CR became 64.71% after the following radiotherapy. CAR-T cell peaks were higher in R-C group than in C-R group, and higher in R-C (1-3 mons) group than that in R-C (more than 3 mons) group. Three patients in R-C group died of CRS, no patient in C-R group died of CRS. There was no difference in CRS and ICANS in R-C and C-R group. CRS and ICANS grades were higher in R-C (1-3 mons) group than that in R-C (more than 3 mons) group. Conclusions: Radiotherapy bridging CAR-T therapy had higher ORR. While, CAR-T therapy followed by radiotherapy might improve CR without higher CRS and ICANS. Trial registration number ChiCTR1800019622.