Osimertinib after definitive chemoradiotherapy in unresectable stage III epidermal growth factor receptor-mutated non-small-cell lung cancer: analyses of central nervous system efficacy and distant progression from the phase III LAURA study.

Background: Distant metastases in non-small-cell lung cancer (NSCLC) are a poor prognostic factor that negatively impact quality of life. The central nervous system (CNS) is a common site of distant progression in epidermal growth factor receptor-mutated (EGFRm) NSCLC. Osimertinib is a third-generation EGFR-tyrosine kinase inhibitor recommended for advanced EGFRm NSCLC and as adjuvant treatment for resected EGFRm NSCLC. In LAURA (NCT03521154), osimertinib demonstrated statistically significant improvement in progression-free survival (PFS) versus placebo in unresectable stage III EGFRm NSCLC without progression during/following chemoradiotherapy (CRT). CNS efficacy and time to death or distant metastases (TTDM) analyses are reported here.

Patients And Methods: Patients without progression during/following definitive platinum-based CRT were randomised 2 : 1 to receive osimertinib (80 mg daily) or placebo until progression [by blinded independent central review (BICR)] or discontinuation. The primary endpoint was PFS by BICR. CNS PFS by neuroradiologist BICR and TTDM by BICR were secondary endpoints.

Results: Overall, 216 patients were randomised (143 osimertinib, 73 placebo). Median CNS PFS by neuroradiologist BICR was not reached [95% confidence interval (CI) not calculable (NC)-NC] with osimertinib versus 14.9 months (95% CI 7.4 months-NC) with placebo; hazard ratio (HR) for CNS PFS: 0.17 (95% CI 0.09-0.32). CNS PFS analysis by investigator assessment was consistent with BICR assessment. The cumulative incidence of CNS progression at 12 months was 9% (95% CI 5% to 14%) with osimertinib and 36% (95% CI 24% to 47%) with placebo. There was clinically meaningful improvement in TTDM with osimertinib versus placebo; HR for TTDM: 0.21 (95% CI 0.11-0.38). The cumulative incidence of distant metastases at 12 months was 11% (95% CI 6% to 17%) with osimertinib and 37% (95% CI 26% to 48%) with placebo.

Conclusions: Osimertinib demonstrated clinically meaningful improvements in CNS PFS and TTDM versus placebo, supporting osimertinib post-CRT as the standard of care in unresectable stage III EGFRm NSCLC.