#ESMO26 | PERSEE – Phase III In advanced NSCLC with PD-L1 ≥50%, adding chemotherapy to pembrolizumab improved median PFS from 6.9 to 16.1 months (HR 0.56). The numerical OS difference was notable (50.2 vs 29.9 months; HR 0.77), but not statistically significant. However, we should remember that OS was not the primary endpoint! Grade ≥3 toxicity: 53.8% vs 19.3%. I think adding chemotherapy provides benefit, but at the cost of increased toxicity. We need to better identify the patients for whom this toxicity is worth it.