EGFR Exon 20 Mutations

This is a Phase 1b, open-label, multi-center, dose-escalation and dose expansion study designed to evaluate the safety, pharmacokinetics (PK), and preliminary antitumor activity of furmonertinib in patients with advanced or metastatic non-small cell lung cancer (NSCLC) with activating, including uncommon, Epidermal Growth Factor Receptor (EGFR) or Human Epidermal Growth Factor Receptor 2 (HER2) mutations. Patients will be enrolled into one of 2 stages: Stage 1 (Dose Escalation and Backfill Cohorts) and Stage 2 (Dose Expansion).