Results from a study presented at the American Society for Radiation Oncology (ASTRO) Annual Meeting suggested that radiation therapy administered to patients with relapsed or refractory multiple myeloma awaiting CAR T-cells is safe and feasible without worsening rates of severe cytokine release syndrome (CRS), neurotoxicity, or hematologic toxicity.1
These new findings lend more support to future studies that combine radiation with cellular therapy.
“The most important takeaway here is that bridging radiation doesn’t appear to increase the risk of CRS or neurotoxicity,” lead author Shwetha Manjunath, MD, a resident in Radiation Oncology in the University of Pennsylvania Perelman School of Medicine, said in a press release.2 “These patients safely received bridge radiation without it affecting the efficacy of CAR T-cells or the rates of toxicity.”
Overall, 25 patients with relapsed or refractory multiple myeloma were treated in 3 cohorts, including 9 patients treated with 1-5 x 108 CART-BCMA cells (cohort 1), 5 with cyclophosphamide (Cy) 1.5 g/m2 + 1-5 x 107 CART-BCMA cells (cohort 2), and 11 with Cy 1.5 g/m2 + 1-5 x 108 CART-BCMA cells (cohort 3). Researchers then retrospectively collected details on radiation therapy, response, toxicity, and CAR T manufacturing data.
Group 1 consisted of 13 subjects who received no radiotherapy within 1 year prior to CAR T infusion. Group 2 was made up of 8 subjects who received radiotherapy within 1 year prior to CAR T infusion with a median time from radiotherapy to apheresis of 88.5 days (range 15-295). Moreover, group 3 consisted of 4 subjects who received bridging radiotherapy with a median time from apheresis to radiotherapy of 17 days (range 14-22) and from radiotherapy to CAR T infusion of 34 days (range 21-42).