Since the combination of trastuzumab or pertuzumab and a single-agent chemotherapeutic is the standard first-line treatment for most patients with HER-2-positive breast cancer, we chose to study the effects of PPRHs directed against ERBB2 sequences in combination with trastuzumab, a more targeted HER-2-therapy than chemotherapy. The gene discussed is ERBB2; the disease is breast carcinoma.