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Vinorelbine/Trastuzumab Produces Synergistic Effects in HER2-Positive Metastatic Breast Cancer

Vinorelbine/Trastuzumab Produces Synergistic Effects in HER2-Positive Metastatic Breast Cancer

At the 24th Annual San Antonio Breast Cancer Symposium,
researchers reported a 78% overall response rate in a phase II trial of
vinorelbine (Navelbine) plus trastuzumab (Herceptin) in women with HER2-positive
metastatic breast cancer. According to FDA-approved labeling, vinorelbine is not
indicated for metastatic breast cancer.

"The response rate from our multicenter study and a previously reported
response rate of 75% from an earlier single-site trial are both very
encouraging," said Mohammed Jahanzeb, md, research director of the Boca
Raton Comprehensive Cancer Center and professor of biomedical research at
Florida Atlantic University, referring to an earlier investigation at the
Dana-Farber Cancer Institute in Boston (J Clin Oncol 14:2722-2730, 2001).

The phase II trial investigated the safety and efficacy of trastuzumab and
vinorelbine as first-line therapy for metastatic breast cancer in women with
tumors that overexpress the HER2 protein. The trial enrolled 40 patients who
received weekly intravenous doses of trastuzumab and vinorelbine administered
over 4-week cycles. After receiving at least two cycles, 37 patients were
evaluated for a response. A total of 4 complete and 25 partial responses were
observed for an overall response rate of 78%. Disease progression developed in
four patients, and four remained stable.

Tolerability With Combination

After a cumulative total of 313 cycles, significant toxicity (consisting of
grade 4 neutropenia) was seen in 30% of patients, in 14% of cycles. Grade 3
neutropenia occurred in 50% of patients, in 20% of cycles. One patient was
hospitalized with neutropenic fever. No grade 3/4 nausea, vomiting, heart
disturbance, or hair loss was reported. Grade 3/4 nonhematologic toxicity
consisted of grade 3 fatigue in one patient, grade 4 fatigue in one patient, and
grade 3 neurotoxicity in one patient. The addition of vinorelbine did not appear
to change the side-effect profile of trastuzumab, which was also shown to be
well tolerated.

"We didn’t want to increase side effects in our efforts to potentially
increase efficacy, so in selecting an agent to use in combination with
Herceptin, which is well tolerated, we chose to study Navelbine," said
Dr. Jahanzeb.

Previous Findings

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