93P Immunotherapy in advanced/metastatic lung cancer: A real-world study of long-term survivors

Background: Consolidative thoracic radiotherapy (CTRT) improves outcomes in advanced non-small cell lung cancer (NSCLC) after chemotherapy (CT).However, the efficacy and safety of high-dose CTRT following immune checkpoint inhibitors (ICIs) are not fully characterized.This study evaluates CTRT outcomes and toxicity in NSCLC patients previously treated with (CT-)ICIs.Methods: A retrospective single-institution analysis was conducted on patients receiving CTRT after first-line (CT-)ICIs.Primary endpoints were local failure-free survival (LFFS), progression-free survival (PFS), and overall survival (OS) using the Kaplan-Meier method.Toxicities were graded via Common Terminology Criteria for Adverse Events (CTCAE).Results: 43 patients with NSCLC treated between 2019 and 2024 were included.At presentation, 48.8% had locally advanced disease unsuitable for definitive chemoradiotherapy, while 51.2% were metastatic.Most (88.4%) received PD-1 inhibitors (median 6 cycles, range 1-31).CTRT median equivalent dose in 2 Gy fractions was 50.0 Gy, with 51.2% receiving radical doses (median 59.2 Gy) and 48.8% subradical doses (median 48.8 Gy).At a median follow-up of 35.7 months (95% CI: 28.9-45.3):-Survival: 1-year and 3-year LFFS were 87.1% and 66.4%.Median PFS was 19.6 months (95% CI: 9.8-NE); median OS was 48.8 months (95% CI: 15.5-NE).-Toxicity: Grade 2 radiation pneumonitis (RP) incidence was 27.9% (occurring at a median of 2.3 months post-CTRT).Grade 3 and Grade 5 RP occurred in 11.6% and 2.3%, respectively.-Correlations: Acute Grade 2 RP was significantly associated with prior ICI duration (9.5% for 6 cycles vs. 40.0%for 7 cycles; p= .03).Prescribed CTRT dose did not significantly impact RP rates (27.3% radical vs 28.6% subradical, p= .92).-Overall Pulmonary Events: Grade 2, grade 3 and grade 5 pulmonary event rates (all etiologies) were 32.6%, 18.6% and 7.0%, respectively. Conclusions:For advanced NSCLC responding to first-line ICIs, high-dose CTRT provides encouraging oncological control with manageable toxicity.Notably, prolonged ICI administration prior to CTRT significantly increases the risk of acute RP.