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March 14, 2007

Promising New Anti-cancer Treatment Approved For HER2-Positive Breast Cancer

Topics: Medicine

lapatinib.jpg

Tykerb is part of a new generation of cancer drugs that specifically attack cancer-causing proteins.
The FDA has approved Tykerb (lapatinib), a new targeted anti-cancer treatment that is significantly more effective than current medicines in fighting advanced stage of breast cancer, for use in combination with capectabine (Xeloda), another cancer drug, for patients with advanced, metastatic breast cancer that is HER2 positive (tumors that exhibit HER2 protein): The combination treatment is indicated for women who have received prior therapy with other cancer drugs, including an anthracycline, a taxane, and trastuzumab (Herceptin). According to the American Cancer Society, about 180,000 new cases of breast cancer are diagnosed each year. Approximately 8,000 to 10,000 women die from metastatic HER2 positive breast cancer each year.
Tykerb, a new molecular entity (NME), is a kinase inhibitor working through multiple pathways (targets) to deprive tumor cells of signals needed to grow. Unlike, for example, trastuzumab - a monoclonal antibody, which is a large protein molecule that targets the part of the HER2 protein on the outside of the cell - Tykerb is a small molecule that enters the cell and blocks the function of this and other proteins. Because of this difference in mechanism of action, Tykerb works in some HER2 positive breast cancers that have been treated with trastuzumab and are no longer benefiting.
HER2-positive tumors (about 20% of invasive breast tumors) are more likely to have spread to nearby lymph nodes and less likely to have receptors for the hormones estrogen and progesterone -- both characteristics that are linked to a greater risk of recurrence and death.
The original enthusiasm surrounding lapatinib was in having an oral tyrosine kinase inhibitor that affected both ErbB1 and ErbB2 or HER2, and that blocking multiple receptors would be the key to success. Now researchers are finding that it's much more difficult to understand in which tumors EGFR1, as an overexpressed receptor or as a protein, is a factor in cancer cell growth. This is in direct contrast to the situation in breast cancer, where the story of ErbB2 overexpression and trastuzumab as the inhibitor is clearly a pathway to success in shrinking the tumor.
Tykerb is administered orally. Stimulation of ErbB1 and ErbB2 is associated with cell proliferation and with multiple processes involved in tumor progression, invasion, and metastases. Overexpression of these receptors has been reported in a variety of human tumors and is associated with poor prognosis and reduced overall survival.

There may also be applications for Tykerb with other solid tumors, such as in prostate, bladder, head and neck cancer, and down the road, maybe lung cancer. However, the most promising second area for lapatinib looks like head and neck cancer (such as in squamous cell carcinoma), where a number of responses to single-agent therapy have occurred.

Readers can find more on the approval of Tykerb at News-Medicine.net.

Posted by Richard at March 14, 2007 10:44 PM



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