Inclusion Criteria:

   - Histologically confirmed diagnosis of unresectable Stage IIIB or Stage IV relapsed or
   recurrent NSCLC.

   - Subjects must have:

      1. documented (radiological or clinical) progressive disease (PD) following a prior
      response (including stable disease) to monotherapy with erlotinib or gefitinib
      that was administered for at least 12 weeks prior to progression OR

      2. a documented T790M EGFR mutation

   - Measurable disease defined according to RECIST

   - ECOG performance status of 0 or 1.

   - Sexually active subjects must use an accepted method of contraception during the
   course of the study.

   - Female subjects of childbearing potential must have a negative pregnancy test at
   enrollment.

Exclusion Criteria:

   - Received radiation to ≥25% of his or her bone marrow within 30 days of XL647
   treatment.

   - Received erlotinib or gefitinib, or other anticancer therapy within 14 days of the
   first dose of study drug.

   - Received an investigational drug (excluding erlotinib or gefitinib) within 30 days of
   the first dose of study drug.

   - Receiving anticoagulation therapy with warfarin.

   - Not recovered to Grade ≤1 from adverse events (AEs) due to antineoplastic agents,
   investigational drugs, or other medications that were administered prior to study
   enrollment.

   - Corrected QT interval (QTc) of >0.45 seconds.

   - Progressive, symptomatic, or hemorrhagic brain or leptomeningeal metastases.

   - Requires steroid or anticonvulsant therapy for the treatment of brain metastases.