Lapatinib (Tykerb) is a new breast cancer drug currently undergoing for patients with breast cancer who have over expression of HER2 gene. A new clinical study has demonstrated that Lapatinib is an effective treatment for breast cancer patients who may have HER2 gene over expression and are not controlled by Herceptin, which is the most common drug used in that setting.

Approximately twenty percent of breast cancer patients may have over expression of the HER2 gene and these breast cancer patients usually do worse in comparision to breast cancer patients who do not have HER2 gene amplification. The drug Herceptin is routinely used in breast cancer patients who have HER2 gene over amplification. But with ongoing treatment the cancer might develop resistance towards herceptin and in such situations the drug becomes ineffective to treat that patients breast cancer. Lapatinib is effective in such patients who have developed resistance to herceptin. In a recent clinical study Lapatinib has shown to double the time for progression of cancer to 8.5 months in comparison to using chemotherapy alone. All patients, who participated in this study, had amplification of HER2 gene and had breast cancer progression while receiving herceptin treatment. Lapatinib causes anticancer property by blocking two biochemical pathways that involve ErbB1 and ErbB2 and has lesser side effects in comparison to herceptin.

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