Study of ASLAN001 in Combination With Capecitabine in MBC That Has Failed on Prior Trastuzumab

Phase 2A Design: 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 mg/m2 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. Criteria to Proceed to Phase 2B: In the absence of any safety or tolerability concerns, continuation to the Phase 2B part of the study will be primarily based on the statistical comparison of the percentage change in tumor size from baseline to Week 12 and a one-sided p-value \<0.1 in favor of the ASLAN001-containing treatment arm would be supportive of continuation to Phase 2B. Phase 2B Design: The Phase 2B part of the study will continue to recruit if the pre-specified efficacy criteria are met in the Phase 2A part and if the tolerability of ASLAN001 in combination with capecitabine is considered acceptable. The Phase 2B part is an open-label, randomized, parallel group study. In this part, approximately 160 patients will be randomized in a 1:1 ratio to receive either ASLAN001 400 mg BID or lapatinib 1250 mg QD, both in combination with capecitabine 1000 mg/m2 BID for Days 1-14 of a 21-day cycle.