Phase I/II study of gemcitabine in association with vinorelbine for metastatic breast cancer.

BACKGROUND: Gemcitabine (G) and vinorelbine (V) have favorable safety profile and antitumor activity in metastatic breast cancer. To exploit their different mechanism of action and lack of overlapping toxicity, we performed a phase I and II study of G and V in combination.

PATIENTS AND METHODS: Fifty-three patients with metastatic breast cancer were treated. In the dose-finding phase, seven cohorts of patients (22 women) received increasing doses to determine the dose limiting toxicity (DLT) and maximum tolerated dose (MTD) of the combination. Patients recruited in the phase II portion of the study (31 women) received the dose level immediately below the one defined as MTD (i.e., G 1200 mg/m2, V 30 mg/m2, on day 1 and day 8, every 3 weeks).

RESULTS: Dose escalation was discontinued at G 1400mg/m2 and V 30 mg/m2 because of toxic death due to thrombocytopenia and CNS hemorrage. No other limiting toxicities were observed, and tolerability was similar at all dose levels studied in the escalation portion of the study. The main toxicity was granulocytopenia of grade 3/4 in 36 and 48% of the patients on phase I and II respectively, without episodes of neutropenic fever. Thrombocytopenia was uncommon. Other side effects were usually mild to moderate. In 46 evaluable patients, the response rate was 24% (complete response 7%, partial response 17%). Disease stabilization was observed in further 17%. The median duration of response was 12 months (range 5-14) and the median survival was 20 months (range 1 to 45+).

CONCLUSIONS: G and V, on day 1 and 8 of 3-weekly cycles, can safely be administered to patients with metastatic breast cancer at the dose of 1200 and 30 mg/m2, respectively. The antitumor activity of G and V in combination was similar to that reported when using either drug as single agent.