Gemcitabine-taxane experience in the treatment of metastatic breast cancer.

Management of metastatic breast cancer (MBC) is difficult and overall response rates (ORR) resulting from anthracycline and taxane-based regimens remain modest. The antimetabolite drug gemcitabine has been shown to have high activity when used as first-line treatment of MBC, particularly when incorporated into combined therapy regimens. Gemcitabine-containing regimens have also been used successfully as salvage therapy in women with anthracycline or taxane-pretreated MBC. Phase II clinical studies have demonstrated high ORR with gemcitabine-docetaxel (ORR: 36-65.5%) and gemcitabine-paclitaxel (ORR: 40-68%) combination regimens. A highly favourable risk-benefit ratio has also been reported for gemcitabine-containing triplets such as gemcitabine-paclitaxel-epirubicin (ORR: 92%) and gemcitabine-paclitaxel-doxorubicin (ORR: 80.4%). Gemcitabine-containing regimens have a favourable toxicity profile with few serious toxic events reported. An important step forward in the evaluation of novel chemotherapeutic regimes for MBC is establishing a correlation between disease markers and response to therapy. Preliminary data suggest that there is a close relationship between HER2 extracellular domain levels (>30 ng/ml) and treatment outcome. HER2-positive patients had a lower ORR to gemcitabine-paclitaxel chemotherapy than women who were HER2-negative. Further studies to establish a link between other breast cancer markers and predicted response to treatment are warranted.