A new anti-cancer agent that targets breast cancer can overcome resistance to cancer drugs, according to a new study. Many tumours that are initially responsive to chemotherapy can develop resistance to it, allowing the cancer to progress. Studies have shown that one of the key reasons for the development of resistance is a protein pump called P-glycoprotein. Resistant cancer cells express P-glycoprotein and this removes anti-cancer drugs from the cell before they are able to kill the cell.
The new study shows that P-glycoprotein is not able to remove a recently identified anti-cancer agent known as STX140 from cancer cells. STX140 works by stimulating a natural cell suicide process and is able to kill cancer cells which express the P-glycoprotein pump.
For the new study, mice with drug-resistant tumours were given either STX140 or a currently used clinical drug, Taxol, for 28 days. The drug-resistant tumours shrank in size in response to STX140 whereas the drug-resistant tumours treated with Taxol continued to increase in size.
Dr Simon Newman, lead author of the paper* from the Oncology Drug Discovery and Women's Health Group at Imperial College London, said: "Whilst the research is still at a very early stage the results of our studies show that STX140 may, in the future, have a role to play in difficult to treat advanced drug-resistant breast cancer.
"STX140 is potentially a very exciting new drug as it may be given by the oral route at regular intervals, and, as this new study has shown, it can target tumours which are resistant to many currently used anti-cancer drugs. However, before STX140 can progress to the clinic numerous further studies will have to be undertaken to ensure the safety of this exciting compound," Added Dr Newman.
*Journal reference: Clinical Cancer Research 2008 Jan 15; 14(2): 597-606.
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