Protein therapy to stop cancer from spreading

A protein therapy may soon offer a safe and effective alternative to chemotherapy that doctors today apply to try to slow or stop cancer from spreading.

The experimental therapy has been shown to stop spread of breast and ovarian cancers in mice.

The protein therapy disrupts the process that causes cancer cells to break away from original tumour sites, travel through the blood stream and start aggressive new growths elsewhere in the body, a process known as metastasis that can cause cancer to spread with deadly effect, the findings showed.

"This is a very promising therapy that appears to be effective and non-toxic in pre-clinical experiments," said co-researcher Amato Giaccia, a professor at the Stanford University in the US.

"It could open up a new approach to cancer treatment," Giaccia added.

Today doctors try to slow or stop metastasis with chemotherapy, but these treatments are unfortunately not very effective and have severe side effects.

The researchers sought to stop metastasis by preventing two proteins - Axl and Gas6 - from interacting to initiate the spread of cancer.

Axl proteins stand like bristles on the surface of cancer cells, poised to receive bio-chemical signals from Gas6 proteins.

When two Gas6 proteins link with two Axls, the signals that are generated enable cancer cells to leave the original tumour site, migrate to other parts of the body and form new cancer nodules.

To stop this process, the researchers used protein engineering to create a harmless version of Axl that acts like a decoy.

This decoy Axl latches on to Gas6 proteins in the blood stream and prevents them from linking with and activating the Axls present on cancer cells.

The researchers gave intravenous treatments of this bio-engineered decoy protein to mice with aggressive breast and ovarian cancers.

Mice in the breast cancer treatment group had 78 percent fewer metastatic nodules than untreated mice.

Mice with ovarian cancer had a 90 percent reduction in metastatic nodules when treated with the engineered decoy protein.

The study appeared in the journal Nature Chemical Biology.