5 1.1 Disease Background ........................................................................... 5 1.2 HER2 and Breast Cancer .................................................................... 6 1.3 Herceptin Clinical Experience ............................................................. 7 1.4 Safety .................................................................................................. 8 1.5 Clinical Pharmacokinetics of Trastuzumab ......................................... 9 1.6 E75 Background .................................................................................. 10 1.7 HER2-Directed Therapies in HER2 Low-Expressing Tumors ............. 12 1.8 Combined HER2-Directed Therapy ..................................................... 13 2.