Tykerb at present costs breast cancer victims as much as $4,000 each month but will be available on the PBS from next month.
Federal Health minister Nicola Roxon says for most people the drug is costly and making it available on the PBS will mean many women who might otherwise not have been able to have the drug will now be able to.
Tykerb is used to treat HER-2 positive metastatic or advanced breast cancer and is taken once daily in tablet form.
Clinical trials have shown that when given in combination with chemotherapy, lapatinib slows the development of advanced breast cancer, nearly doubling the length of time it takes for the disease to progress (8.4 months) compared to treatment with chemotherapy alone (4.4 months).
About 20-25 per cent of people diagnosed with breast cancer each year have HER-2 positive breast cancer which is a more aggressive form of the disease.
Advanced or metastatic breast cancer means the cancer cells have spread from the breast to other areas of the body, such as the bones or lungs and around 15 per cent of women diagnosed with breast cancer in Australia have advanced or metastatic disease.
Chang and first author David Wong, MD, PhD, postdoctoral scholar, began to answer the question of how cancer stem cells originate by comparing genetic activity in embryonic stem cells with the activity in normal adult stem cells. They found a large group of genes that were active only in embryonic cells. They then looked at which genes were active in cancer stem cells and found that the pattern resembled that of embryonic stem cells.
The finding was a surprise, given that once embryonic stem cells become committed to forming adult cells, such as skin, brain or blood, they were thought to forever deactivate those embryonic genes. Instead, Chang said this work suggests that when those adult cells become cancerous, they turn those embryonic genes back on.
The group also noticed that the genes active in both embryonic and cancer stem cells are controlled by a few biological master regulators. One of those genes, called Myc, has also been shown recently to help convert normal skin cells into embryonic-like cells.
By activating two genes in addition to Myc in normal skin cells, those cells were transformed into what appeared to be cancer stem cells. When transplanted into laboratory mice, the cells formed tumors, one hallmark of a true cancer stem cell.
From here, Chang and Wong hope to learn more about how these genes activate a cancerous state. "Our particular interest is in using this approach to find the mechanism that turns a normal cell into a cancer stem cell," said Chang, who is also the Kenneth G. and Elaine A. Langone Scholar of the Damon Runyon Cancer Research Foundation.
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