Biomarker subset analysis of a phase IIIb, open-label study of afatinib in EGFR tyrosine kinase inhibitor-naive patients with EGFR m+ non-small-cell lung cancer.

Aim: To explore the relationship between mutations in cfDNA and response to afatinib. Patients & methods: In total, 64 patients from one Chinese site with locally advanced/metastatic EGFR m+ non-small-cell lung cancer, who received afatinib 40 mg once daily, were included. Results: Overall, 33 (82.5%) patients became EGFR m- by visit 3; median progression-free survival was longer in these patients vs those who did not (11.0 vs 5.5 months). Progression-free survival was shorter in 42 (45.2%) patients with non- EGFR co-mutations at baseline vs those without (8.1 vs 12.5 months). Neither difference was significant. Conclusion: Afatinib provided clinical benefit for patients with EGFR m+ non-small-cell lung cancer across all subgroups. EGFR m status assessment in plasma cfDNA is a useful method of monitoring treatment.