Overall survival with adjuvant atezolizumab after chemotherapy in resected stage II-IIIA non-small-cell lung cancer (IMpower010): a randomised, multicentre, open-label, phase III trial

Background: IMpower010 (NCT02486718) demonstrated significantly improved disease-free survival (DFS) with adjuvant atezolizumab versus best supportive care (BSC) following platinum-based chemotherapy in the programmed death-ligand 1 (PD-L1)-positive and all stage II-IIIA non-small-cell lung cancer (NSCLC) populations, at the DFS interim analysis. Results of the first interim analysis of overall survival (OS) are reported here.

Patient and methods: The design, participants, and primary-endpoint DFS outcomes have been reported for this phase III, open-label, 1 : 1 randomised study of atezolizumab (1200 mg q3w; 16 cycles) versus BSC after adjuvant platinum-based chemotherapy (1-4 cycles) in adults with completely resected stage IB (≥4 cm)-IIIA NSCLC (per the Union Internationale Contre le Cancer and American Joint Committee on Cancer staging system, 7th edition). Key secondary endpoints included OS in the stage IB-IIIA intent-to-treat (ITT) population and safety in randomised treated patients. The first pre-specified interim analysis of OS was conducted after 251 deaths in the ITT population. Exploratory analyses included OS by baseline PD-L1 expression level (SP263 assay).

Results: At a median of 45.3 months' follow-up on 18 April 2022, 127 of 507 patients (25%) in the atezolizumab arm and 124 of 498 (24.9%) in the BSC arm had died. The median OS in the ITT population was not estimable; the stratified hazard ratio (HR) was 0.995 [95% confidence interval (CI) 0.78-1.28]. The stratified OS HRs (95% CI) were 0.95 (0.74-1.24) in the stage II-IIIA (n = 882), 0.71 (0.49-1.03) in the stage II-IIIA PD-L1 tumour cell (TC) ≥1% (n = 476), and 0.43 (95% CI 0.24-0.78) in the stage II-IIIA PD-L1 TC ≥50% (n = 229) populations. Atezolizumab-related adverse event incidences remained unchanged since the previous analysis [grade 3/4 in 53 (10.7%) and grade 5 in 4 (0.8%) of 495 patients, respectively].

Conclusions: Although OS remains immature for the ITT population, these data indicate a positive trend favouring atezolizumab in PD-L1 subgroup analyses, primarily driven by the PD-L1 TC ≥50% stage II-IIIA subgroup. No new safety signals were observed after 13 months' additional follow-up. Together, these findings support the positive benefit-risk profile of adjuvant atezolizumab in this setting.