There are numerous other single agent drugs with good activity in metastatic
breast cancer, such as Paclitaxel (Taxel), the anthracyclines doxorubicin
and epirubicin, docetaxel,
and gemcitabine. The use of single agent chemotherapy is associated with less treatment-related toxicity as compared with combination therapy.
If one stops working, the patient can be switched to another one. There are also newer drugs currently in clinical trials that may prove useful.