METHODS: Eligible Asian patients (enrolled at Asian sites) who were at least 18 years of age (≥20 years in Japan) and had untreated EGFR-mutated advanced NSCLC were randomized 1:1 to receive osimertinib (80 mg, orally once daily) or an SoC EGFR TKI (gefitinib, 250 mg, or erlotinib, 150 mg, orally once daily). The primary end point was investigator-assessed progression-free survival (PFS). The key secondary end points were overall survival, objective response rate, central nervous system efficacy, and safety.
RESULTS: The median PFS was 16.5 versus 11.0 months for the osimertinib and SoC EGFR TKI groups, respectively (hazard ratio = 0.54, 95% confidence interval: 0.41-0.72, p < 0.0001). The overall survival data were immature (24% maturity). The objective response rates were 80% for osimertinib and 75% for an SoC EGFR TKI. The median central nervous system PFS was not calculable for the osimertinib group and was 13.8 months for the SoC EGFR TKI group (hazard ratio = 0.55, 95% confidence interval: 0.25-1.17, p = 0.118). Fewer adverse events of grade 3 or higher (40% versus 48%) and fewer adverse events leading to treatment discontinuation (15% versus 21%) were reported with osimertinib versus with an SoC EGFR TKI, respectively.
CONCLUSION: In this Asian population, first-line osimertinib demonstrated a clinically meaningful improvement in PFS over an SoC EGFR TKI, with a safety profile consistent with that for the overall FLAURA study population.
EXPERIMENTAL DESIGN: Tumor tissue EGFRm status was determined at screening using the central cobas tissue test or a local tissue test. Baseline circulating tumor (ct)DNA EGFRm status was retrospectively determined with the central cobas plasma test.
RESULTS: Of 994 patients screened, 556 were randomized (289 and 267 with central and local EGFR test results, respectively) and 438 failed screening. Of those randomized from local EGFR test results, 217 patients had available central test results; 211/217 (97%) were retrospectively confirmed EGFRm positive by central cobas tissue test. Using reference central cobas tissue test results, positive percent agreements with cobas plasma test results for Ex19del and L858R detection were 79% [95% confidence interval (CI), 74-84] and 68% (95% CI, 61-75), respectively. Progression-free survival (PFS) superiority with osimertinib over comparator EGFR-TKI remained consistent irrespective of randomization route (central/local EGFRm-positive tissue test). In both treatment arms, PFS was prolonged in plasma ctDNA EGFRm-negative (23.5 and 15.0 months) versus -positive patients (15.2 and 9.7 months).
CONCLUSIONS: Our results support utility of cobas tissue and plasma testing to aid selection of patients with EGFRm advanced NSCLC for first-line osimertinib treatment. Lack of EGFRm detection in plasma was associated with prolonged PFS versus patients plasma EGFRm positive, potentially due to patients having lower tumor burden.