Breast cancer research is entering a new and promising phase, with greater focus on patient quality of life and therapy selection based on specific targets of interest. Growth factor pathway modulators represent an area of increasing interest for clinicians treating various cancer types, including breast cancer. Therapeutic strategies combining cytotoxic drugs with specific targets using small molecules and targeted antibody therapy may help circumvent potential growth factor survival mechanisms in solid tumors. One of the challenges when combining these agents, however, is the potential for pharmacodynamic and pharmacokinetic interactions, making safety an important consideration. An example of a growth factor pathway modulator with clinical application in breast cancer is trastuzumab. Based on its efficacy in metastatic disease, ongoing clinical trials are examining trastuzumab in combination with chemotherapy in the adjuvant setting. Concerns about the cardiac safety of trastuzumab given concomitantly with conventional anthracyclines support ongoing investigations of regimens combining it with liposomal anthracyclines, based on available data indicating a more favorable cardiac safety profile with liposomal formulations.