INCLUSION CRITERIA

          -  Age ≥ 18 years

          -  Histologically or cytologically confirmed metastatic or advanced inoperable diagnosis
             of NSCLC

          -  Documented radiographic progression on the last treatment administered prior to
             enrolling in the study.

          -  Phase 1 only: Confirmation that the tumor harbors an EGFR mutation known to be
             associated with aberrations that are amenable to EGFRi therapy including but not
             limited to: G719X, exon 19 deletion, exon 21 L858R, and L861Q. OR - Must have
             experienced clinical benefit from an EGFRi,

          -  All acute toxic effects of any prior antitumor therapy resolved to Grade ≤1 or
             baseline before the start of study drug dosing (with the exception of alopecia [any
             grade permitted] and neurotoxicity [Grade 1 or 2 permitted]).

          -  Measurable disease meeting the criteria specified by RECIST v1.1

          -  Phase 2, Cohort 1 only: Subjects must have confirmation of tumor T790M mutation status
             (confirmed positive) and are osimertinib naïve

          -  Phase 2, Cohort 2 only: EGFR aberrations that are amenable to EGFRi therapy, including
             but not limited to: G719X, exon 19 deletion, exon 21 L858R, and L861Q, and be EGFRi
             naïve

        EXCLUSION CRITERIA

          -  Subjects who have received only neoadjuvant or adjuvant therapy for NSCLC.

          -  Phase 1 only: Treatment with an EGFRi within 7 days or 5 half-lives of the first dose
             of study treatment, whichever is shorter.

          -  Phase 1 only: Cytotoxic chemotherapy, investigational agents, or any anticancer
             therapy for the treatment of advanced NSCLC (other than EGFRi) within 21 days of the
             first dose of study treatment.

          -  Prior treatment with immunotherapy within 3 months prior to the first dose of study
             treatment.

          -  Radiotherapy within 28 days of first dose of study treatment; subjects given
             palliative radiotherapy to peripheral sites (e.g., bone metastases) may enter the
             study before 28 days have elapsed provided the radiated sites do not contain lesions
             which may be used to evaluate response, and must have recovered from any acute,
             reversible effects.

          -  Known or suspected central nervous system (CNS) metastases or leptomeningeal disease
             (Phase 1 only). Subjects with previously treated brain or CNS metastases are eligible
             provided that the subject has recovered from any acute effects of radiotherapy, does
             not have brain metastasis related symptoms, is not requiring systemic steroids for at
             least 2 weeks prior to study drug administration, and any whole brain radiation
             therapy was completed at least 4 weeks prior to study drug administration, or any
             stereotactic radiosurgery (SRS) was completed at least 2 weeks prior to study drug
             administration.

          -  Prior allogeneic bone marrow transplantation.

          -  History of a concurrent or second malignancy except for: adequately treated local
             basal cell or squamous cell carcinoma of the skin; cervical carcinoma in situ;
             superficial bladder cancer; breast carcinoma in situ; adequately treated Stage 1 or 2
             cancer currently in complete remission; any other cancer that has been in complete
             remission for ≥5 years.