110P Pembrolizumab vs atezolizumab as first-line treatment for advanced NSCLC with PD-L1-expression ≥50%

Results: A total of 1,068 patients were included.At a median follow-up of 38.1 months, median PFS was 10.4 months (95% CI, 9.4-11.7)and median OS was 16.5 months (95% CI, 14.4-18.5).5-year PFS and OS rate was 19.1% and 16.7%, respectively.Median OS and PFS were comparable across PD-L1 expression subgroups (<1%, 1-49%, 50%), with no significant differences (log-rank p=0.87 and p=0.79, respectively).Objective response rate (ORR) was 44%, disease control rate (DCR) was 73%, and the median duration of response (DoR) was 17.4 months (95% CI, 14.7-21.4).Eighty-six patients (8.0%) received 35 cycles of pembrolizumab.Among the 687 patients who experienced PD, 127 (18.5%) continued treatment beyond PD; 58.4% of these patients received a local treatment at the site of progression, almost exclusively radiotherapy (98.6%).Median OS was significantly longer in patients who continued treatment beyond PD compared with those who discontinued therapy (24.8 vs 13.1 months, HR 0.55, p<0.001).In the second-line (2L) setting, 142 (30.3%) patients received taxane monotherapy, 96 (20.5%) taxane plus anti-angiogenic and 70 (15.0%)other chemotherapy regimens.At a median follow-up of 21.3 months from initiation of 2L treatment, the median 2L-PFS was 4.0 months (95% CI: 3.7-4.7).Overall, the 2L-ORR and 2L-DCR were 15.6% and 45.3%, respectively. Conclusions:In a real-world setting, first-line platinum-pemetrexed-pembrolizumab provides durable clinical benefit in a subset of patients, regardless of PD-L1 expression.Continuation of treatment beyond PD combined with local therapies may be associated with a survival advantage in selected patients.Nevertheless, outcomes after PD remain poor, highlighting the unmet need for more effective second-line treatment strategies.