OSCILLATE: This phase II trial is alternating the use of two oral drugs (Osimertinib and Gefitinib) in patients with advanced EGFR-T790M positive Non-Small Cell (NSC) Lung CancerPhase 2 trial to determine the efficacy, safety, and feasibility of alternating osimertinib with gefitinib in patients with EGFR-T790M mutation positive advanced non-small cell lung cancer

Exclusion

1. Previous or current treatment with osimertinib or other drugs that target EGFR-T790M mutations, e.g. CO-1686, HM61713, TAS-121
2. Contraindications to investigational product
3. Any unresolved toxicity from prior therapy worse than CTCAE grade 1, except alopecia and grade 2 neuropathy due to prior platinum-based chemotherapy
4. Major surgery within 4 weeks, or palliative radiation therapy within 5 days before enrollment
5. Treatment with prohibited medications (e.g. concurrent anti-cancer therapy including other chemotherapy, or immunotherapy within 14 days prior to treatment)
6. Patients currently receiving (or unable to stop at least 1 week before starting osimertinib) potent inhibitors or inducers of cytochrome P450 (CYP) 3A4
7. Patient with symptomatic central nervous system (CNS) metastases who are neurologically unstable, or require increasing doses of steroids to manage CNS symptoms within 2 weeks prior to starting osimertinib. Patients with leptomeningeal carcinomatosis are also excluded
8. Known history of interstitial lung disease from any cause
9. Life expectancy of less than 3 months
10. Mean QT interval corrected for heart rate (QTc) >= 470 ms OR any clinically important abnormalities in rhythm, conduction or morphology of resting ECG OR any factors that increases the risk of QTc prolongation or risk of arrhythmic events