Key Eligibility Criteria:

          -  Eastern Cooperative Oncology Group (ECOG) performance status 0-1

          -  Confirmed recurrent Stage IV NSCLC which progressed while on treatment with EGFR TKI

          -  Measurable disease according to Response Evaluation Criteria in Solid Tumors version
             1.1 (RECIST 1.1)

          -  Documented evidence of an EGFR mutation known to be associated with an EGFR TKI
             sensitivity

          -  No T790M mutation or small cell transformation including an assessment from tumor
             biopsy obtained while on or subsequent to the most recent EGFR TKI therapy

          -  Acceptable laboratory results as indicated by protocol

          -  Acceptable cardiac function as indicated by protocol

        Key Exclusion Criteria:

          -  Receiving medication that prolongs QT interval, with a risk of causing Torsades de
             Pointes (TdP) unless ECG meets inclusion criteria while on a stable dose of the
             medication

          -  Family history of long QTc syndrome

          -  Symptomatic central nervous system (CNS) lesions

          -  Radiation therapy within 2 weeks prior to the first dose of study medication

          -  Major surgery within 4 weeks or minor surgery within 2 weeks prior to the first dose
             of study medication

          -  Concurrent active malignancy requiring systemic treatment

          -  Any other serious uncontrolled medical disorders or psychological conditions that may
             interfere with study conduct including but not limited to: clinically significant
             active infection (e.g., tuberculosis, viral hepatitis, human immunodeficiency virus
             [HIV]), recent (within 6 months) myocardial infarction or unstable angina, congestive
             heart failure, poorly-controlled hypertension or diabetes, concurrent active
             malignancy, or psychiatric condition that may interfere with the patient's ability to
             follow study procedures

          -  Pregnant or breast-feeding