Radiation and Chimeric Antigen Receptor T-cell Therapy in B-cell Non-Hodgkin Lymphomas

Chimeric antigen receptor T-cell therapy (CAR-T) is a revolutionary advancement in the management of chemotherapy refractory B-cell non-Hodgkin lymphomas representing a potentially curative therapy in scenarios that were previously only palliative. CAR-T cell therapy is associated with unique toxicities as well as practical challenges. One of those challenges is how to manage active lymphoma during the weeks-long CAR-T manufacturing process. Radiation therapy, steroids, and systemic therapy have all been used for what would be considered "bridging therapy" during this time frame. Radiation therapy is a particularly attractive strategy given its proven efficacy in chemotherapy refractory lymphomas; ability to stabilize patients, debulk disease, and palliate symptoms; as well as its potential to enhance the expansion and activity of CAR-T cells. Optimal dose, timing, and method of delivery are yet to be established though there is consensus that it should occur after apheresis if being used as a pre-treatment bridge. Another practical challenge is the management of patients in whom CAR-T cells fail. There is a potential emerging role for salvage radiation therapy, in select patients, for either palliation or as a means to get patients another potentially curative therapy. Collaborative well-designed prospective clinical trials are needed to definitively establish the role for radiation therapy (before or after CAR-T therapy) as well as define the impact on CAR-T cell activity/persistence and associated toxicity.