Phase II study of weekly edatrexate as first-line chemotherapy for metastatic breast cancer: a National Cancer Institute of Canada Clinical Trials Group study.

PURPOSE: The National Cancer Institute of Canada (NCIC) Clinical Trials Group conducted a phase II study to assess the efficacy and toxicity of edatrexate, a folate antagonist, in 35 patients with metastatic breast cancer. PATIENTS AND METHODS: The planned dose of edatrexate was 80 mg/m2/wk administered intravenously as first-line therapy. Prior adjuvant chemotherapy was allowed provided at least 12 months had elapsed from the completion of treatment to the development of recurrence.
RESULTS: Mucositis was the dose-limiting toxicity in 34 assessable patients, resulting in a mean delivered dose-intensity of 57 mg/m2/wk. Other toxicities included myelosuppression, rash, pneumonitis, and increased AST. Side effects were generally mild to moderate. The complete plus partial remission rate (13 patients; 41%) was impressive.
CONCLUSION: Edatrexate is an active agent against metastatic breast cancer, with acceptable toxicity. A lower than planned delivered dose-intensity was mainly due to mucositis.