This study looks at using two medicines, MRX-2843 and osimertinib, to treat a type of lung cancer called non-small cell lung cancer that has changes in a gene called EGFR and has spread in the body. The goal is to find the best dose and see what side effects might occur. The medicines work by stopping certain cell growth processes. Patients will take both medicines by mouth once a day for 28 days, and this cycle repeats as long as the cancer doesn't get worse or side effects aren't too bad. After the study, patients are monitored for at least 30 more days.

• The study involves repeating 28-day cycles of daily medicine intake.
• Participants must have a type of lung cancer that has a specific gene change.
• Women and men must use birth control during the study as effects on unborn babies are unknown.