New therapies in the treatment of breast cancer

Systemic therapy for breast cancer is undergoing many interesting advances. In recent years, a better understanding of the underlying biology of cancer has led to the identification of several opportunities to target cellular pathways for therapeutic advantage. Hormonal therapy is often chosen as the first line of therapy because it is generally very well tolerated. However, most patients eventually become unresponsive to endocrine manipulation. Improved understanding of the mechanisms of hormonal resistance, and of the interplay between hormone receptors and cellular growth pathways, provides the rationale for combining signal transduction inhibitors and hormonal agents to overcome resistance. Emerging data from preclinical studies suggest that this goal might be achievable in the clinic. Antiangiogenic therapy has shown efficacy in colorectal and lung cancer and appears promising in breast cancer, although improved overall survival has not yet been shown. There have also been advances in cytotoxic chemotherapy. Reformulation of paclitaxel in polyoxy-castor-oil-free albumin nanoparticles (ABI-007) has allowed more convenient, safer, and enhanced drug delivery with associated improvement in outcomes. New agents with novel mechanisms of action are also in development and appear to have activity in cancer cells that are resistant to currently available agents.