ESTRO 2025 - Abstract Book

S1286

Clinical - Lung

ESTRO 2025

5

Digital Poster Predictors and effects of durvalumab induced pneumonitis on outcomes in patients with LANSCLC treated according to the Pacific protocol. Sarit Appel 1 , Yaacov Richard Lawrence 1,2 , Jair Bar 3 , Lee Wilk 1 , Jeffery Goldstein 4 1 Radiation Oncology, Sheba Medical Center, Ramat Gan, Israel. 2 Radiation Oncology, Sidney Kimmel Medical College at Thomas Jefferson University, Philadelphia, USA. 3 Medical Oncology, Sheba Medical Center, Ramat Gan, Israel. 4 Radiation Oncology, Sourasky Medical Center, Tel Aviv, Israel Purpose/Objective: We hypothesized that durvalumab (DURV) induced pneumonitis (DIP) contributes to poor outcomes in patients treated with chemoradiation (CRT) and DURV. Material/Methods: We analyzed cases with LANSCLC treated according to Pacific protocol criteria (CRT ≥60 Gy+DURV) extracted from a single academic institution IRB approved database to identify patient, tumor and treatment variables that predict for DIP and its effect on local control (LC), progression free survival (PFS), and overall survival (OS). Results: Database review identified 119 patients, 65% male, mean age 66 years (SD 8), 58% stage IIB-IIIA, and 51% adenocarcinoma, for inclusion in the cohort. DIP occurred in 35 (29.4%) cases early in treatment (mean 2.6 months, range 0.3-11), was mostly low grade: G1-12; G2-18; G3-3; G4-1; G5-1 and resulted in treatment interruption in 24 pts. (20%) with discontinuation in 17 pts. (14.3%). Univariate analysis (UVA) showed correlation between all - grades DIP and advanced tumor stage (HR 1.9, p=0.06), use of adaptive replanning (HR 2.1, p=0.024), total lung V20 ≥27% (HR 2, p=0.043), ipsilateral lung V5 ≥70% (HR 2.2, p=0.027), mean lung dose (MLD) ≥16Gy (HR 2.1, p=0.05), heart V40 ≥6% (HR 2.0 p=0.045) and mean heart dose (MHD) ≥6 Gy (HR 2.5, p=0.017). Significant correlations for grade 2-5 DIP included use of adaptive replanning (HR 2.1, p=0.025), total lung V20 ≥27% (HR 3.3, p=0.005), ipsilateral lung V5 ≥71% (HR 2.4, p=0.045), MLD ≥15Gy (HR 2.5, p=0.032), heart V40 ≥4% (HR 2.4, p=0.041) and MHD ≥6Gy (2.8, p=0.029). Multivariate analysis (MVA) showed all grades DIP correlated with tumor stage, ipsilateral lungV5 ≥70% and MH ≥6Gy and grades 2-5 DIP correlated with total lungV20 ≥27% and MHD ≥6 Gy.DIP did not correlate with age, gender, weight loss at presentation, performance status, IHD, smoking, COPD, tumor histology, chemotherapy, or prior radiation pneumonitis (RP)(9/119)(fig 1).