e18809 Background: Consolidation treatment with durvalumab following CRT is now standard of care for pts with unresectable stage III NSCLC. In PACIFIC, durvalumab was administered within 42 days of completing CRT. There has also been recent interest in whether the time-of-day immunotherapy is given impacts on outcomes. In practice, many pts experience delays to consolidation immunotherapy, and the timing of infusions is variable. We investigated the effect of treatment delays and time-of-treatment on survival outcomes in a real-world setting. Materials & Methods: A retrospective observational study was conducted with patients treated with consolidation durvalumab following concurrent platinum-based CRT for unresectable stage III NSCLC in 6 centres across Sydney, Australia between January 2018 and September 2021. The primary outcomes were overall survival (OS) and progression-free survival (PFS) based on RECIST v1.1, from completion of radiotherapy. We collected treatment initiation and completion dates as well the administration time of durvalumab. In the time-of-treatment analysis, pts were stratified into median time of treatment either before or after 12.00pm. Survival was estimated using Kaplan-Meier and Cox-proportional hazard models. Results: 145 pts were included in the study. Median age was 67 years. 62.3% of pts were male, 84.9% were smokers, and 57.5% had adenocarcinoma. The median time between completion of CRT and commencement of durvalumab was 59 days (11-187 days). 71.2% (n = 102) of pts experienced a treatment delay. Over a median follow-up of 18.9 months, median PFS was 33.9 months in pts treated within 42 days of CRT and 25.6 months in pts treated beyond 42 days of CRT (HR 0.97; 95% CI 0.46-2.06; p = 0.815). Median OS was not reached in either group but no difference in OS was observed in the two cohorts (HR 1.07; 95% CI 0.39-2.96; p = 0.88). Median timing of treatment did not affect outcomes for either PFS (HR 1.07; 95% CI 0.50-1.71; p = 0.80) or OS (HR 1.01; 95% CI 0.44-2.31; p = 0.91). Conclusions: No difference in survival outcomes was seen between patients who had received durvalumab 42 days after CRT compared to within 42 days. The median timing of treatment did not appear to impact outcomes in our cohort.