The impact of radiotherapy on the therapeutic response of patients treated with CAR T-cell therapy for high-grade lymphoma: a systematic review

Chimeric antigen receptor T (CAR -T) cell therapy is a promising form of cancer treatment with proven efficacy in relapsed/refractory lymphomas. However, there are limitations, including toxicity, failure to achieve immunological memory, and immune evasion. The rationale for administering radiotherapy (RT) with CAR -T, includes increased antigen exposure and immune activation. We studied the current evidence for RT use in high-grade lymphoma patients treated with CD19 CAR-T therapy. The outcomes of interest included progression free survival, complete response rate, overall survival, and incidence of treatment associated toxicities. Five studies were included encompassing 1034 patients. The results indicate that RT is a safe and effective bridging strategy. The combination of RT and CAR-T is associated with improved complete remission rates, but the evidence is limited by cohort heterogeneity and possible selection bias. Further prospective trials are required to confirm this and to determine whether survival outcomes are affected.