S520
Clinical - Haemotology
ESTRO 2026
from our region (South-east Asia). Material/Methods:
20–40 Gy). Median time from the end of RT to CAR-T cell infusion was 28.5 days ( range 16–66) Mean time from end of radiotherapy to CAR-T infusion: 42.8 days( range: 5–76) days. Results: RT bridging was well toleratedas no patient discontinued RT due to toxicity. CRS was evaluable in 20 patients and occurred in 14/20 (70%); it was predominantly low grade (grade 1: n=10; grade 2: n=1; grade 3: n=3). ICANS was uncommon (1/20 evaluable patients; grade 3). At last follow-up, 12/21 patients were alive (10 in complete remission, 2 with active disease). Nine patients died: 6 fordisease progression, 2 for infectious/respiratory or hematologic complications and 1 for de novo AML Median overall survival from CAR-T infusion to last follow-up was 29.3 months (range 9.9–47.5). Conclusion: Bridging RT, either alone or combined with polatuzumab/bendamustine, is safe and feasible as excellent acute tolerability and seamless alignment with CAR-T timelines were observed. Notably, 8/21 patients in our series received combined radiotherapy plus polatuzumab/bendamustine as bridging, offering early real-world evidence of the feasibility and acute safety of this integrated approach. Prospective studies should define field selection, dose/fractionation, and integration with systemic agents. Keywords: Bridging radiotherapy CD19 CAR T-cell therapy Utility of Radiation Therapy in CAR T therapy Tianpei Li 1 , Francesca LWI Lim 2 , Yunxin Chen 2 , Chandramouli Nagarajan 2 , Yeh Ching Linn 2 , Hein Than 2 , Jeffrey KS Quek 2 , Lawrence CK Ng 2 , Tertius T Tuy 2 , Desmond SW Lim 3 , Wei Ying Tham 3 , David CE Ng 3 , Chieh Hwee Ang 2 , Kye Ling Wong 2 , Melinda SY Tan 2 , Shin Yeu Ong 2 , William YK Hwang 2 , Kheng Wei Yeoh 1 1 Division of Radiation Oncology, National Cancer Centre Singapore, Singapore, Singapore. 2 Department of Haematology, Singapore General Hospital, Singapore, Singapore. 3 Department of Nuclear Medicine and Molecular Imaging, Singapore General Hospital, Singapore, Singapore Purpose/Objective: Chimeric antigen receptor T-cell (CAR T) therapy is a novel therapy for relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL). Areas of improvement still exist in the timing and delivery of CAR T, especially bridging and holding therapy. For disease which is relatively bulky or locoregional, radiotherapy (RT) has been shown to be beneficial. As research in this field continue to evolve, we hereby present initial evidence Digital Poster 4347
A retrospective review, from the initiation of the CAR T program, was conducted for patients with DLBCL who received RT before CAR T at our institution. Results: From January 2021 to May 2025, 16 patients received holding/bridging RT at the National Cancer Centre Singapore prior to CAR T. Median age of patients was 60 (20-80) at time of CAR T. 10 male and 6 female patients were included. 8 out of 16 (50%) patients were in the relapsed setting and the remaining were primary refractory. Follow up ranged from 5 months to 4 years. Median progression-free survival was 15 months (0-46.4) while overall survival was not reached. RT was given either as consolidation treatment or as palliation. Gross target volumes (GTV) range from 8.98 to 857.68mls. Total lesion glycolysis (TLG) range from 38.3 to 14271 SUVmls. Patients received 1.8-4Gy per fraction with median total dose of 27 Gy (16 - 36 Gy). 10 patients received bridging systemic therapy. Patients received various CD-19 directed CAR T constructs, consisting of tisagenlecleucel, axicabtagene ciloleucel or in-house academic CD-19 directed CAR-T product. Local response rate was 93.8% (15/16). Thereafter, 3 patients (18.8%) had in-field progression and 3 (18.8%) had out-of-field progression. At last follow up, 9 patients (56.3%) remain in complete response, while 6 patients (37.5%) had passed. Patients with higher TLG has poorer outcomes. No patient had grade 3 or 4 toxicities from the RT. All patients had manageable CAR T-related toxicities with grade 0-2 cytokine release syndrome (CRS) and grade 0-1 immune effector cell-associated neurotoxicity syndrome (ICANS); 1 patient had grade 4 CRS due to overall pre-CAR T disease bulk. Conclusion: RT shows efficacy and safety for patients undergoing CAR T therapy. Further areas for optimization include volume, dose, fractionation and sequencing to improve CAR T outcomes. Ongoing investigation in these areas should continue to optimize the outcomes
for patients undergoing CAR T. Keywords: CAR T, bridging, Asia
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Time trends in dose to breast tissue and other mediastinal organs-of-interest in young women treated for lymphoma: a single institutional cohort study Rory A D Bell 1 , Hannah C Chamberlin 1 , Christina Hague 2 , Richard Cowan 2 , John Radford 1,2 , Joanna Williams 2,1 , Sacha J Howell 2,1 , Edward G A Henderson 3 , Kim Linton 4,1 , Eliana M Vasquez Osorio 1 , Marianne Aznar 1
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