We have relatively little in the way of studies regarding specific agents for triple-negative breast cancer, but there is some emerging data that I think is interesting. If we look in the E2100 trial of Taxol (chemical name: paclitaxel) alone vs. Taxol with Avastin (chemical name: bevacizumab) as front-line therapy for metastatic breast cancer, Taxol and Avastin was superior to Taxol in triple-negative patients to the same degree it was in estrogen-receptor-positive patients. On the opposite end, we have some very interesting and recent adjuvant data which is from a trial performed by the CALGB (Cancer and Leukemia Group B) in elderly breast cancer patients (age 65 or greater) newly diagnosed and receiving adjuvant chemotherapy. This trial randomized patients to one of two older chemotherapy regimens, AC (Adriamycin [chemical name: doxorubicin] and Cytoxan [chemical name: cyclophosphamide]) or CMF (Cytoxan, methotrexate, and fluorouracil) vs. the use of single agent Xeloda (chemical name: capecitabine). The results of that trial were particularly interesting in that in women who had steroid-receptor-negative tumors, Xeloda appeared to perform particularly poorly with a hazard ratio for recurrence of 4.4 vs. other groups treated with chemotherapy and estrogen-receptor-positive patients. This suggests the possibility that Xeloda is simply not a very good drug for triple-negative breast cancer patients, certainly not in the adjuvant setting. There is another trial that I presented at ASCO a little over a year ago, called the XCALIBr trial, which looked at the combination of Xeloda and Avastin as front line therapy for metastatic breast cancer. While patients who were estrogen-receptor positive did relatively well in this trial, the triple-negative patients did extremely poorly. Putting together the CALGB trial as well as the XCALIBr trial, one lesson I draw from this is that Xeloda would not be my initial therapy for patients with a triple-negative breast cancer.
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