Is lapatinib plus vinorelbine effective in HER2 positive metastatic breast cancer?

This paper studied the effectiveness of lapatinib (Tyverb) plus vinorelbine (Navelbine) in treating women with HER2 positive metastatic breast cancer.

Human epidermal growth factor receptor 2 (HER2) positive breast cancer (elevated levels of HER2 protein in cells) is associated with worse cancer outcome. Though trastuzumab (Herceptin) has been shown to be very effective for these patients, some patients may see cancer progression despite treatment. 

Lapatinib plus capecitabine (Xeloda) has previously shown to be effective in  treating HER2 positive metastatic (has spread to other parts of the body) breast cancer. Lapitinib is a drug that inhibits HER2, while capecitabine is a form of chemotherapy drug.  

Vinorelbine is a new chemotherapy drug  that works by blocking HER2. It is suggested that combining vinorelbine with lapatinib might also be effective.   

The authors evaluated the lapatinib plus capecitabine compared to lapitinib plus vinorelbine.

112 women with HER2 positive metastatic breast cancer were studied. 75 patients were assigned to receive lapatinib plus vinorelbine. 37 patients were assigned to receive lapatinib plus capecitabine. Patients were allowed switch treatments. 29 patients switched to receive capecitabine while 13 patients switched to receive vinorelbine.

The average progression-free survival (period of time without disease worsening) was 8.8 months in patients who received vinorelbine and 8.3 months in patients who received capecitabine. Average overall survival was 24.3 months in vinorelbine group and 19.4 months in capecitabine group. Tumour size decreased in 20% of vinorelbine group and 49% of capecitabine group. After some patients switched treatment, the average progression-free survival was 3.2 months for patients who switched to vinorelbine and 4 months for patients who switched to capecitabine.

15% of patients who received vinorelbine and  16% of patients who received capecitabine stopped treatment due to an adverse event (unwanted side effect of drug). Most common adverse events included diarrhoea, low white blood cell levels, rash, nausea and fatigue. Serious adverse events, such as low white blood cells levels, occurred in 33% of vinorelbine group and 11% of capecitabine group. Before some patients switched treatment, death occurred in 19% of patients receiving vinorelbine group and 19% of patients receiving capecitabine. Adverse events were similar in patients who switched treatment. 

The authors concluded that lapatinib plus vinorelbine gave comparable results to lapatinib plus capecitabine and is effective in treating  HER2 positive metastatic breast cancer.

This was a small scale study.