47P Timing of radiotherapy affects outcomes of patients with metastatic NSCLC who receive immunotherapy

Radiotherapy (RT) and immunotherapy (IO) may have synergistic anti-tumor effect for treating metastatic non-small-cell lung cancer (mNSCLC). However, the optimal timing of RT in relevance to IO whether it affects outcomes is unknown. We conducted a retrospective study all patients with mNSCLC treated at our institution (2011–2022). Patients who received targeted therapy or prior concurrent chemoRT + durvalumab were excluded. In this cohort 225 patients, 56% male, 82% Caucasian. The median age was 68 (44–95). histology predominantly adenocarcinoma (79%). most common sites bone (41%) followed by CNS (25%). before during IO. 27% never RT. 17% after discontinuation Pembrolizumab used (78%), Nivolumab (14%) Atezolizumab (12%). Most frontline (60%). observed no statistical difference PFS, OS, development immune-related adverse events compared without (PFS: 5.9 vs. 5.5 months, p = 0.66; OS: 16.9 13.1 0.84; irAE: 26.2% 34.4%, 0.24). divided into four groups related IO: >12 months (N 29), between 1 12 39), <1 month 30), initiation 28). PFS (months) above 4.3, 12.6, 4.2, 5.1, respectively, OS 16.5, 25, 13.9, 16, respectively. found significantly higher IO, those RT<1 (12.6 4.2 0.005, HR 0.46, 95% CI 0.26–0.83), 0.0197, 0.56, 0.36–0.89). This trend sustained analysis (25 13.9 0.08; 25 0.18). statistically significant clinically meaningful benefits There positive benefit, although not significant. These findings need be verified larger cohort.