425P Final analysis of the phase Ib-II trial of dendritic cell vaccination plus atezolizumab in ES-SCLC (VENEZOLUNG)

Results: A total of 91 patients were included, with the cTRT group exhibiting a more favorable ECOG performance status and lower tumor burden.Unadjusted analyses revealed that patients who received cTRT had significantly longer median PFS and median OS (P < 0.001).However, given the patient selection bias in this retrospective study, IPTW was applied to adjust for confounding.After weighting, survival differences were attenuated but remained numerically in favor of the cTRT group, with a weighted median PFS of 13.77 vs. 10.07 months, and a median OS of 31.87 vs. 17.27 months.Cox analysis showed receipt of cTRT was independently associated with prolonged both PFS (HR 0.54; P = 0.036) and OS (HR 0.45; P = 0.033).DpR analysis showed a higher rate of additional tumor shrinkage in the cTRT group (74.4% vs. 46.2%;P = 0.007).Toxicities were manageable; most radiation-related events were grade 1-2 (33.3%), and no grade 5 adverse events (AEs) occurred. Conclusions:In this real-world cohort, cTRT following chemoimmunotherapy yielded more pronounced tumor shrinkage and exerted an independent association with improved survival outcomes.Prospective randomized trials are warranted to further define the optimal role of cTRT in the immunotherapy era.