RADIOTHERAPY BRIDGING IN LARGE B‐CELL LYMPHOMA PATIENTS RECEIVING CD19 CAR‐T – THE UK EXPERIENCE

Background: Radiotherapy (RT) has potential synergistic effects with CAR T but is not widely used as bridging therapy for lymphoma patients due to logistical challenges, uncertainty about patient selection and lack of standardised protocols. Published data on RT are so far restricted single-centre analyses. Methods: We analysed in a large multi-centre national cohort B-cell (LBCL) approved 3rd line axicabtagene ciloleucel (axi-cel) or tisagenlecleucel (tisa-cel) between December 2018 October 2022 across 12 UK centres. Results: Of 763 patients, 722 (95%) were leukapheresed, 717 had available therapy. 170/717 (24%) received bridging, 129 single modality 41 combined treatment (CMT). Use varied centres from 11% 32%, increased 19% (2018–19) 26% (2021–22; p = 0.034). Median age bridged was 60 y. 69% de novo LBCL, 8% PMBL, 35% tFL 6% transformed other low-grade lymphoma. Disease characteristics follows: 66% advanced stage, 41% bulk, 87% elevated LDH, 42% IPI ≥ 3, 17% double/triple hit. Patients given less likely have stage ≥2 extranodal sites versus those receiving systemic therapy/CMT (61% vs. 85/83% 18% 30/39%, respectively; < 0.05). time approval infusion 56 days no difference modalities. Infusion rates 88% (vs. 84%, 85%, 85% steroids, therapy, respectively (p 0.41)). Data (in-field) response 46 patients: 10% CR, 65% PR, SD, PD. Details techniques, anatomical locations toxicities 68 will be provided at the meeting. Doses 2–39 Gy used, including combination multiple doses; 40 IMRT. Only one experienced G3–4 toxicity RT. The overall incidence G 3 CRS 5.2% ICANS 16.3%, significant according approaches. follow-up 16 months. favourable outcomes 1-y PFS 56% 47% CMT, OS 56%, (Figure 1). associated both limited (1-y 59% (43—72) 50% (39–61), respectively. Keywords: aggressive non-Hodgkin lymphoma, cellular therapies, radiation Conflicts interests pertinent abstract A. Kuhnl Consultant advisory role: Kite/Gilead, Novartis, BMS Honoraria: Novartis Kirkwood Kite/Gilead Gibb Latif