Saturday, February 25, 2012

Drug may treat previously untreatable cancers

A drug that is currently in clinical trials may have unprecedented efficacy in the treatment of certain cancers. Various studies have shown that it is highly effective in slowing down cancers that would otherwise be difficult or impossible to treat. Its effect can be explained because it works on two mechanisms that help spread cancer and make it deadly, New Scientist explains. According to scientists, its effect on cancer patients is truly remarkable, which naturally is very good news.

Most drugs only function in one or a few cancers. That is because it is an extremely diverse disease: our body has a lot of different cells, so there is an equal variety in tumours. After extensive testing however, cabozantinib, as the drug is known, was proven to be effective in 12 of 13 cancer types. Being effective in so many forms of the disease is unusual, but it also proved to have a high efficacy.
When tested in a group of patients with prostate cancer that had already spread to the bones, administering cabozantinib proved to be very effective. In 82 out of the 108 participants, the tumour decreased in size. In some of them it even disappeared completely from the bones. Also, many of them reported a decrease in pain levels. Other studies reported similar success stories for kidney and thyroid cancer. It is remarkable that a drug can be so effective against a form of cancer that already managed to develop itself so well that it spread to other tissues.

One of the neat features of cabozantinib is indeed its capability to prevent spread of the cancer cells throughout the body. When tumours acquire the functionality of travelling throughout the body and nesting in other organs, it makes them much more deadly. The drug blocks this process by attacking a specific receptor on the cellular surface of the cells. It is called C-met, and it functions by activating certain signalling pathways on the inside that are beneficial for cancer cells, apparently especially when they want to move away from their current location. 

Blood flow
There is more that makes cabozantinib effective. It is also capable of inhibiting the growth of blood vessels into the tumour. In turn, cancer cells are deprived of oxygen and nutrients, and the tumour is not able to grow larger. To achieve this, cabozantinib binds to another receptor called VEGFR. This one picks up signals necessary for blood vessel outgrowth. Combining the two effects is what seems to give cabozantinib its efficacy.
Blood vessels have expanded towards the tumour, which aids the spread of cancer cells throughout the body by blood. It is easy to see why blocking both processes is a good idea.
Being effective in many forms of cancer and reducing lethal cancer spread makes the drug a winner. Equally important is the fact that it is already being used in large clinical trials, which makes it safe to assume we will see it in the clinic relatively soon. 

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