 The Phase 2A part is an open-label, randomized, parallel group study using tumor size as its primary efficacy endpoint. Approximately 44 eligible patients will be randomized in a 1:1 ratio to receive either ASLAN001 400 mg orally twice daily BID or lapatinib 1250 mg orally once daily QD, both on a background of capecitabine 1000 mgm2 orally BID for Days 1-14 of a 21-day cycle. Radiological imaging to assess disease status will be performed at baseline and every 6 weeks until disease progression as assessed by the Investigator. Patients who have not experienced disease progression after 12 weeks may continue to receive randomized therapy and will continue to have radiological scans every 6 weeks until disease progression. 