The new generation of targeted therapies for breast cancer

Traditional therapies for breast cancer have generally relied upon the targeting of rapidly proliferating cells by inhibiting DNA replication or cell division. Although this strategy has been effective, its innate lack of selectivity for tumor cells has resulted in diminishing returns, approaching the limits of acceptable toxicity. A growing understanding of the molecular events that mediate tumor growth and metastases has led to the development of rationally designed targeted therapeutics that offer the dual hope of maximizing efficacy and minimizing toxicity to normal tissue. Promising strategies include the inhibition of growth factor receptor and signal transduction pathways, prevention of tumor angiogenesis, modulation of apoptosis, and inhibition of histone deacetylation. This article reviews the development of several novel targeted therapies that may be efficacious in the treatment of patients with breast cancer and highlights the challenges and opportunities associated with these agents.