Dr Wang on the Safety Profile of CNS Bridging Radiotherapy Prior to CAR T in B-Cell Lymphoma

“The safety profile that we observed was very acceptable. We did not observe any grade 2 or higher acute or late radiation-related neurotoxicity.”

Pule Wang, MD, a radiation oncology fellow in the Department of Radiation Oncology at City of Hope, discussed safety data from a retrospective study of bridging radiation therapy prior to CAR T-cell therapy in patients with central nervous system (CNS) involvement from relapsed/refractory B-cell lymphomas.

The study included 26 patients with relapsed/refractory B-cell lymphoma involving the CNS who were treated with bridging radiation therapy followed by CAR T-cell therapy at City of Hope; the patient population consisted of those with diffuse large B-cell lymphoma (n = 22) and mantle cell lymphoma (n = 4). During the 2025 American Society for Radiation Oncology (ASTRO) Annual Meeting, Wang presented findings from the study which showed that patients who received partial brain radiation (n = 18), who had a median gross tumor volume of 19.38 cc (range, 4.42-51.02), experienced a mean decrease of lesion size prior to CAR T-cell therapy of 43.0% (95% CI, 22.2%-63.8%).

In terms of safety, the profile of the treatment approach was acceptable, Wang began. There were no instances of grade 2 or higher acute or late onset bridging radiation therapy neurotoxicity among patients with brain parenchymal disease (n = 14), she noted. A significant portion of this subgroup (35.7%) received memantine for neuroprotection, she noted.

Following CAR T-cell therapy 10 patients in the overall population (n = 26) immune effector cell-associated neurotoxicity syndrome (ICANS), Wang said. This rate is similar to that reported in the historical literature of CAR T-cell therapy, she added. In the subgroup of patients with brain parenchymal disease, the rate of ICANS was slightly higher with partial brain radiation compared with whole brain radiation, she noted. Overall, the toxicity profile of the approach examined in the retrospective study was similar with that of patients who received CAR T-cell therapy alone, she concluded.