RecruitingPhase 2ProcedureTesting Osimertinib as a Treatment for Lung Cancers With an EGFR Exon 20 ChangeThis phase II trial studies how well osimertinib works in treating patients with non-small cell lung cancer with EGFR exon 20 insertion mutation that is stage IIIB-IV or has come back after a period of improvement (recurrent). Osimertinib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth.