Complete response (CR) in advanced breast cancer is an important predictor of improved survival. The largest experience reported with long-term follow-up in this regard is from M.D. Anderson Hospital, with a median survival of 33 months and 5-year survival of 19% among patients who achieved a CR with doxorubicin-based chemotherapy.19 We believe that our institutional experience to date indicates that CR rates in excess of 20% can be achieved in second-line chemotherapy from the combination of vinorelbine and a taxane, provided that G-CSF is given. For the reasons outlined, we believe that dose density is likely to be important for both classes of agents, but dose intensity may be most important for vinorelbine. Both paclitaxel and docetaxel can be given on a weekly schedule with some success, but it appears that myelosuppression is a more frequent dose-limiting toxicity on this schedule for docetaxel. For the current trial, we therefore propose to study weekly paclitaxel in combination with dose-intensive vinorelbine, utilizing continuous G-CSF support as in our prior studies. We believe that starting doses of 60 mg/m2 for paclitaxel and 20 mg/m2 for vinorelbine will be well tolerated, but our experience to date, treating 3 patients off study at these doses without G-CSF support, indicates that some will require G-CSF even at this dose level: we observed grade 4 neutropenia in 2 of the 3. Our intention in this trial is to determine the optimal dose of these two agents when continuous growth factor support is provided. We will be starting at a ratio of 0.8 for vinorelbine and 0.75 for paclitaxel (assuming 80 mg/m2/week as a "full" dose for the later agent).