A phase II study of weekly vinorelbine and trastuzumab in patients with HER2-positive metastatic breast cancer.

Trastuzumab combined with cytotoxic agents presents encouraging results in metastatic breast cancer (MBC), but cardiac toxicity limits some combinations. The synergism shown with trastuzumab and the favorable tolerability profile of vinorelbine provided the rationale for investigating this combination. Patients with HER2-positive MBC who had received <2 lines of chemotherapy for metastatic disease were included. Vinorelbine (25 mg/m2 on day 2, then weekly on day 1) and trastuzumab (4 mg/kg on day 1, then 2 mg/kg weekly) were administered for a maximum of 6 cycles (1 cycle=3 weeks). A total of 52 patients were enrolled. The median age was 50 years (range, 26-79 years). Ninety percent of the patients had received adjuvant chemotherapy, 42% received a first line of chemotherapy for MBC, and 69% had disease at visceral sites. The overall response rate was 58% (95% CI, 43%-71%). The median time to progression and overall survival were 7 months (95% CI, 5-9 months) and 26 months (95% CI, 20-32 months), respectively. Grade 4 neutropenia was present in 3 courses; neutropenic fever was not reported. The main grade 3 nonhematologic toxicities were asthenia, neuropathy, diarrhea, alopecia, and nausea/vomiting. No patients experienced serious cardiac toxicity. These results confirm that weekly vinorelbine/trastuzumab is an active and safe regimen in patients with HER2-positive MBC with an unfavorable prognosis.