Novel Capecitabine Dosing Schedule in Combination With Lapatinib, Based on the Norton-Simon Mathematical Method in Patients With HER2 Overexpressed/Amplified, Trastuzumab (Herceptin) -Refractory, Metastatic Breast Cancer

Capecitabine 2,000mg twice daily for 7 days followed by a 7-day rest in combination with lapatinib 1,250mg orally daily. Cycle length is 28 days (+/- 2 days).Toxicity assessment will occur q2 weeks for the first 4 weeks, then q4 weeks(+/- 2 days). Radiographic response assessment will take place q12 weeks (+/- 1 week). LVEF assessment will be repeated q12 weeks (+/- 1 week).