Inclusion Criteria:

          -  Age ≥ 18 years.

          -  Willing and able to give written informed consent.

          -  Have histologically or cytologically confirmed advanced NSCLC harboring EGFR
             mutation(s) sensitive to EGFR inhibitors at initial diagnosis per local approved
             label.

          -  Measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1.

          -  Adequate bone marrow and organ function.

          -  Have ECOG performance status of 0 or 1.

          -  Willing to comply with all protocol-required visits, assessments, and procedures.

          -  Able to swallow oral medication.

        Exclusion Criteria:

          -  Concurrent treatment with any systemic anticancer therapy for NSCLC, including any
             approved or investigational agent.

             • Prior therapy with a RAS, RAF, MEK, or ERK inhibitor.

          -  Prior cancer immunotherapy (CIT) (e.g., immune checkpoint inhibitors), unless the CIT
             was followed by a non-CIT containing regimen prior to study enrollment

               -  Anticancer treatment within 21 days of enrollment, except for osimertinib which
                  may be continued during the screening period.

               -  Palliative radiotherapy within 7 days of enrollment.

          -  History of unacceptable toxicity to treatment with osimertinib.

             • Major surgery within the 28 days of enrollment.

          -  Unresolved toxicities from prior systemic therapy greater than NCI CTCAE grade 1 at
             time of enrollment, except alopecia and grade 2 neuropathy due to prior chemotherapy.

          -  Any evidence of severe or uncontrolled systemic disease or evidence of any other
             significant clinical disorder or laboratory finding that renders the patient
             inappropriate to participate in the study.

          -  Impaired cardiovascular function or clinically significant cardiovascular disease.

          -  History or current evidence of retinal pigment epithelial detachment (RPED), central
             serous retinopathy, retinal vein occlusion (RVO), or predisposing factors to RPED or
             RVO.

          -  Pregnant or breastfeeding women.

          -  Contraindication to osimertinib use as per local label.