The effect of adding lapatinib to paclitaxel chemotherapy on survival in HER2 positive metastatic breast cancer patients

This phase III clinical trial evaluated the effects on survival of the drug lapatinib in combination with a standard chemotherapy agent called paclitaxel in newly diagnosed HER2 positive metastatic breast cancer patients. 

Some breast cancer cells have on their surface a protein (receptor) called human epidermal growth factor receptor 2 (HER2). This protein stimulates the growth and division of breast cancer cells. These types of breast cancers are called HER2 positive breast cancers. They respond to treatments such as lapatinib (Tykerb), which limits the activity of HER2. This prevents the cancer from growing and may improve survival. Paclitaxel (Taxol) is a chemotherapy drug used to treat some types of cancer, including breast cancer. It works by stopping the growth and division of cancer cells, which are eventually destroyed. 

This study looked at the treatment of 444 patients with newly diagnosed HER2 positive metastatic (spread to distant organs and tissues) breast cancer. 222 patients in the control group received paclitaxel with an inactive placebo drug. The active treatment group of 222 patients was given paclitaxel in addition to lapatinib. Lapatinib and placebo were given once a day and paclitaxel was given by intravenous (into the vein) injection once a week, for three weeks in repeating cycles.

Results from this study showed that treatment with lapatinib in combination with paclitaxel significantly increased the length of time patients survived. The survival time in the control (placebo) group was 20.5 months compared to 27.8 months in the group treated with lapatinib and paclitaxel. Patients who received lapatinib also had a longer time without disease progression than patients who received placebo (9.7 months compared to 6.5 months). The most common side effects for patients treated with lapatinib were diarrhea, skin rash and high risk of infections. 

Overall, this study showed that treatment with lapatinib in addition to paclitaxel significantly extended survival in patients with HER2 positive metastatic breast cancer.

This study was partly funded by GlaxoSmithKline, the manufacturer of Tykerb.