2915 - Bridging Radiotherapy Prior to Chimeric Antigen Receptor T-Cells for Relapsed/Refractory Non-Hodgkin Lymphoma
Presenter(s)
S. Wang1, Z. X. Yan2, W. L. Zhao2, Y. Han1, M. Zhang1, J. Y. Chen1, G. Cai1, and W. G. Cao1; 1Department of Radiation Oncology, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China, 2Shanghai Institute of Hematology, State Key Laboratory of Medical Genomics, National Research Center for Translational Medicine at Shanghai, Ruijin Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
Purpose/Objective(s): Chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment paradigm for patients with refractory or recurrent (R/R) non-Hodgkin lymphoma (NHL). The use of bridging radiotherapy in combination with CAR T-cell therapy has been proposed as potential strategies to improve patient outcomes, but the impact remains poorly characterized. This study sought to demonstrate the early outcomes and toxicity of bridging radiotherapy prior to CAR-T for R/R NHL.
Materials/Methods: We retrospectively analyzed 117 patients who received bridging radiotherapy followed by CAR-T at our hospital between July 2021 and November 2024. 109 patients had diffuse large B-cell lymphomas (DLBCL, 93.2%). Median age was 59 years. At apheresis, 73 patients (62.4%) had advanced stage disease, 50 (42.7%) had extranodal disease, and 9 (7.7%) had central nervous system (CNS) involvement. Bulky disease (= 5 cm) was in 27.4%. 98 patients (83.8%) also had bridging systemic therapy, excluding steroids. Median time from bridging radiotherapy completion to CAR-T infusion was 14 days (range 5 to 116). Comprehensive bridging radiotherapy was given to 67 patients (57.3%). Bridging radiotherapy was delivered to 140 total sites, most commonly the abdomen/pelvis, head/neck, thorax, and axilla. Median EQD2 was 33.55 Gy (range, 9.17 to 45.19). The most common regimen was 36 Gy in 15 fractions (N=45, 32.1%). We used the Kaplan Meier method to estimate survival, and the log-rank test to compare results.
Results:
The median follow-up period was 17.8 months (range: 0.7–50.4 months). Response rate to CAR-T (CR or PR) was 100/117 (85.5%). The 1-year overall survival (OS), progress-free survival (PFS), and locoregional recurrence free survival were 82.5%, 68.7% and 87.2%, respectively. Disease progression occurred in 39 patients. In patients with disease progression, in-field failure occurred in 14 of them, and only 3 of them were strictly in-field. Majority of failures occurred outside the irradiated fields (36/39, 92.3%). Patients with bulky disease trend to associate with lower PFS (53.2% vs. 74.0%, P = 0.09). We compared the efficacy of comprehensive radiotherapy versus focal radiotherapy, with 1-year PFS rates of 82.3% and 49.7%, respectively (P < 0.001). Regarding safety data, most patients received concurrent systemic therapy, making hematologic toxicity difficult to assess. 23 (19.7%) patients experienced acute non-hematologic toxicity, mainly includes nausea, vomiting, sore throat, and mucositis. No acute non-hematologic toxicity of grade 3 or above occurred.Conclusion:
Incorporating radiation with CAR-T therapy has good outcomes and seems to have been well tolerated in patients with R/R NHL. Our results also showed comprehensive bridging radiotherapy associated with better prognosis.