Protein therapy may stop cancer from spreading

Stanford researchers have developed a new protein therapy that could offer a safe and effective alternative to chemotherapy that is used to stop cancer from spreading.
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.
This process, known as metastasis, can cause cancer to spread with deadly effect, researchers said.
Experimental therapy stopped the metastasis of breast and ovarian cancers in lab mice, pointing towards a safe and effective alternative to chemotherapy, they said.
“The majority of patients who succumb to cancer fall prey to metastatic forms of the disease,” said Jennifer Cochran, an associate professor of bioengineering at Stanford University.
Today doctors try to slow or stop metastasis with chemotherapy, but these treatments are unfortunately not very effective and have severe side effects.
The team seeks to stop metastasis, without side effects, 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 biochemical 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, Cochran 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.
In collaboration with Professor Amato Giaccia, who heads the Radiation Biology Programme in Stanford’s Cancer Centre, 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 per cent fewer metastatic nodules than untreated mice. Mice with ovarian cancer had a 90 per cent reduction in metastatic nodules when treated with the engineered decoy protein.
“This is a very promising therapy that appears to be effective and non-toxic in pre-clinical experiments. It could open up a new approach to cancer treatment,” Giaccia said.
Using genetic manipulation, the team created millions of slightly different DNA sequences. Each DNA sequence coded for a different variant of Axl.
The researchers then used high-throughput screening to evaluate