Background: 1L NIVO + IPI was shown to provide durable long-term overall survival (OS) benefit vs chemo regardless of tumor programmed death ligand 1 (PD-L1) expression in patients (pts) with advanced NSCLC in CheckMate 227 Part 1 (NCT02477826); 3-year OS rates were 33% vs 22% in pts with PD-L1 ≥ 1% (HR, 0.79 [95% CI, 0.67–0.93]) and 34% vs 15% in pts with PD-L1 < 1% (HR, 0.64 [95% CI, 0.51–0.81]). Here we report updated results from the study with 4 years’ minimum follow-up. Methods: Adults with previously untreated stage IV / recurrent NSCLC, no known EGFR/ALK alterations, and ECOG performance status ≤ 1 were enrolled; pts were stratified by squamous (SQ) and non-squamous (NSQ) histology. Pts with PD-L1 ≥ 1% (n = 1189) were randomized 1:1:1 to receive NIVO (3 mg/kg Q2W) + IPI (1 mg/kg Q6W), NIVO alone (240 mg Q2W), or chemo. Pts with PD-L1 < 1% (n = 550) were randomized 1:1:1 to receive NIVO + IPI, NIVO (360 mg Q3W) + chemo, or chemo. OS with NIVO + IPI vs chemo in pts with PD-L1 ≥ 1% was the primary endpoint. Results: With minimum follow-up of 49.4 months (database lock, Feb 18, 2021), pts were at least 2 years beyond the protocol-specified end of immunotherapy treatment. Pts with PD-L1 ≥ 1% continued to show durable benefit with NIVO + IPI vs chemo (HR, 0.76 [95% CI, 0.65–0.90]); 4-year OS rates were 29% (NIVO + IPI), 21% (NIVO), and 18% (chemo). At 4 years, 14% (NIVO + IPI), 10% (NIVO), and 4% (chemo) remained progression free. Among responders, 34%, 30%, and 7% remained in response, respectively. In an exploratory analysis in pts with PD-L1 ≥ 50%, 4-year OS rates were 37% (NIVO + IPI), 26% (NIVO), and 20% (chemo). In pts with PD-L1 < 1%, OS HR for NIVO + IPI vs chemo was 0.64 (95% CI, 0.51–0.81); 4-year OS rates were 24% (NIVO + IPI), 13% (NIVO + chemo) and 10% (chemo). At 4 years, 12% (NIVO + IPI), 7% (NIVO + chemo), and 0% (chemo) remained progression free. Among responders, 31%, 13%, and 0% remained in response, respectively. Among pts who progressed on NIVO + IPI vs chemo, 7% vs 40% (PD-L1 ≥ 1%), and 9% vs 33% (PD-L1 < 1%), received subsequent immunotherapy. Benefit with NIVO + IPI vs chemo was observed for both SQ and NSQ histology (Table). With long-term follow-up, no new safety signals were identified. Conclusions: With 4 years’ minimum follow-up, 1L NIVO + IPI continued to provide durable, long-term OS benefit vs chemo in pts with advanced NSCLC regardless of PD-L1 expression or histology. Clinical trial information: NCT02477826