GM hens pave way for cheaper cancer drugs

Genetically modified chickens that produce human proteins in their eggs can offer a cost-effective method of manufacturing drugs widely used for treating cancer and other diseases, a study has found.

The research, which initially focused on producing high quality proteins for use in scientific research, found the drugs work at least as well as the same proteins produced using existing methods.

According to researchers from the University of Edinburgh in the UK, high quantities of the proteins can be recovered from each egg using a simple purification system and there are no adverse effects on the chickens themselves, which lay eggs as normal.

The findings, published in the journal BMC Biotechnology, provide sound evidence for using chickens as a cheap method of producing high quality drugs for use in research studies and, potentially one day, in patients.

Eggs are already used for growing viruses that are used as vaccines, such as the flu jab. This new approach is different because the therapeutic proteins are encoded in the chicken's DNA and produced as part of the egg white.

The team have initially focused on two proteins that are essential to the immune system and have therapeutic potential -- a human protein called IFNalpha2a, which has powerful antiviral and anti-cancer effects, and the human and pig versions of a protein called macrophage-CSF, which is being developed as a therapy that stimulates damaged tissues to repair themselves.

Just three eggs were enough to produce a clinically relevant dose of the drug. As chickens can lay up to 300 eggs per year, researchers say their approach could be more cost-effective than other production methods for some important drugs.

"We are not yet producing medicines for people, but this study shows that chickens are commercially viable for producing proteins suitable for drug discovery studies and other applications in biotechnology," said Helen Sang, a professor at University of Edinburgh in the UK.

Protein-based drugs, which include antibody therapies such as Avastin and Herceptin, are widely used for treating cancer and other diseases.

For some of these proteins, the only way to produce them with sufficient quality involves mammalian cell culture techniques, which are expensive and have low yields.

Other methods require complex purification systems and additional processing techniques, which raise costs.

Scientists have previously shown that genetically modified goats, rabbits and chickens can be used to produce protein therapies in their milk or eggs.

The approach is more efficient, produces better yields and is more cost-effective than these previous attempts.