A phase I/II study of vinorelbine, doxorubicin, and methotrexate with leucovorin rescue as first-line treatment for metastatic breast cancer

Purpose: This study was performed to determine the maximum tolerated dose (MTD) and toxicity of vinorelbine when used in combination with doxorubicin and methotrexate with leucovorin rescue in women with metastatic breast cancer. Methods: Enrolled in the study were 23 women with metastatic breast cancer who had not received prior chemotherapy for metastatic disease. Patients treated at the first dose level received vinorelbine 20 mg/m² on day 1, doxorubicin 40 mg/m² on day 1, methotrexate 100 mg/m² on day 1 and leucovorin 20 mg orally every 6 h for six doses beginning on day 2. Treatment was repeated every 21 days. The vinorelbine dose was escalated by 5 mg/m² for patients treated at subsequent dose levels. The MTD was defined as the dose level at which fewer than one-third of patients enrolled experienced dose-limiting toxicity (DLT). When the MTD of vinorelbine had been determined, the doxorubicin dose was then escalated by 10 mg/m² with the vinorelbine dose held at its MTD. Results: total of 98 courses of treatment (median of 4 per patient, range 2-8) were administered. The MTD of this regimen was found to be vinorelbine 25 mg/m², doxorubicin 40 mg/m², and methotrexate 100 mg/m² with leucovorin rescue. At higher doses of vinorelbine, neutropenia, fatigue, arm pain, malaise, nausea and vomiting were dose-limiting. Higher doses of doxorubicin resulted in universal dose limiting neutropenia, and frequent nonhematologic DLT consisting of arm pain, malaise, stomatitis, nausea and vomiting. Amongst the 20 patients with measurable disease, there were 3 complete responses (15%, 95% confidence interval 3%-38%), 5 partial responses (25%, 95% confidence interval 9%-49%) and an overall response rate of 40% (95% confidence interval 19%64%). The median survival was estimated to be 25 months from the start of chemotherapy. Conclusions: Vinorelbine at 25 mg/m² can be safely administered with doxorubicin at 40 mg/m² and methotrexate at 100 mg/m² with leucovorin rescue. Response rates observed with this regimen suggest that this combination of chemotherapeutic agents may not be more effective than the combination of vinorelbine and doxorubicin.