Putting taxanes to work in operable breast cancer: a search for selective indications from empirical studies

The taxanes paclitaxel and docetaxel are the prototype drugs of a new class of anticancer drugs that exploits a completely new mechanism of action. Their testing in metastatic breast cancer has been extensive. The results indicating very high response rate with either taxane have given rise to an unprecedented effort in the scientific community to define their optimal application in all stages of the disease. In metastatic breast cancer, initial data suggest that paclitaxel may increase the survival obtained with standard combinations such as CMFP, and similarly promising studies of docetaxel are almost complete. Significant therapeutic benefit has also been observed by the addition of sequential paclitaxel after adjuvant doxorubicin plus cyclophosphamide in operable breast cancer. Overall, more than 20 randomized studies with paclitaxel or docetaxel, either as single agents or in combination, are ongoing or planned in women with high-risk operable breast cancer. This massive effort is mainly based on empirical study designs. However, some preclinical characteristics of the taxanes, such as their increased antitumor effect in tumors overexpressing HER2/neu, the preclinical and clinical evidence of potential synergism with monoclonal antibodies directed against the HER2 receptor, and preclinical evidence of antiangiogenic properties should be pursued to test whether the use of taxanes in breast cancer could be tailored to individual tumor characteristics rather than following the usual pattern of indiscriminate application.