Paclitaxel and mitoxantrone in the treatment of metastatic breast cancer: a phase II trial of the Minnie Pearl Cancer Research Network.

BACKGROUND AND RATIONALE

The combination of paclitaxel and doxorubicin is highly active in the treatment of metastatic breast cancer, but is associated with substantial toxicity. In this phase II trial, we evaluated the combination of paclitaxel and mitoxantrone in an attempt to maintain efficacy and improve tolerability of this regimen.

PATIENTS AND METHODS

Sixty-three patients with metastatic breast cancer were treated with paclitaxel 200 mg/m2, 1 hr i.v. infusion, and mitoxantrone 10 mg/m2 i.v., every 21 days. Responding patients received at least six courses of therapy. Ninety-three percent of patients in this trial were receiving first-line treatment for metastatic breast cancer; 62% of patients had received previous adjuvant chemotherapy, and 26% had received previous doxorubicin.

RESULTS

Objective responses were seen in 24 of 61 evaluable patients (39%). Median response duration was 9 months (range 4-37 + months); actuarial 1-, 2-, and 3-year survivals were 62, 32, and 25%, respectively. The treatment was generally well tolerated; 78% of patients had grade 3 or 4 leukopenia at sometime during their treatment course, but only 14 hospitalizations for neutropenia and fever were necessary (4% of courses). Grade 3 fatigue was experienced by 30% of patients. Cardiotoxicity was not observed.

CONCLUSIONS

The combination of paclitaxel and mitoxantrone is active, easily administered, and well tolerated in the treatment of metastatic breast cancer. Its activity appears similar to several other taxane-based combination regimens recently evaluated for the treatment of advanced breast cancer.