Osimertinib in Treating Participants With Stage I-IIIA EGFR-mutant Non-small Cell Lung Cancer Before Surgery

PRIMARY OBJECTIVES: I. To evaluate the efficacy of osimertinib as neoadjuvant therapy in patients with surgically resectable EGFR-mutant non-small cell lung cancer (NSCLC). SECONDARY OBJECTIVES: I. To evaluate the safety of osimertinib given as neoadjuvant therapy in early stage EGFR-mutant NSCLC participants. II. To evaluate whether neoadjuvant osimertinib treatment increases the frequency of tumors that are unresectable due to adverse events or disease progression. III. To evaluate secondary measures of clinical efficacy in early stage EGFR-mutant NSCLC patients treated with osimertinib induction therapy. TERTIARY OBJECTIVES: I. To evaluate long-term measures of efficacy in patients treated with osimertinib neoadjuvant therapy. II. To explore tissue and cell-free biomarkers that may be predictive of response or primary resistance to osimertinib neoadjuvant therapy. OUTLINE: Participants receive osimertinib orally (PO) once daily (QD) on days 1-28. Treatment repeats every 28 days for up to 2 cycles in the absence of disease progression or unacceptable toxicity. Patients then undergo surgical resection of their cancer. After completion of study treatment, participants are followed up at 30 days then every 3 months for up to 1 year.