Hatching a new way to make drugs

University of Edinburgh researchers say hen eggs are 'set to crack future drug production'

Jeffrey Bouley
EDINGURGH, Scotland—The infamous question, “Which came first: The chicken or the egg?” is perhaps the first thing that pops to mind with recent news from researchers at the University of Edinburgh—or perhaps instead “you can’t make an omelet without breaking a few eggs”—but in any case, in this case, the chickens and the eggs come first.
First in drug production, of all things.
You see, the aforementioned researchers say that chickens that are genetically modified to produce human proteins in their eggs can offer a cost-effective method of producing certain types of drugs.
(And yes, we’re done with the puns and classic chicken/egg tropes.)
The study, 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. They also found that high quantities of the proteins can be recovered from each egg using a simple purification system. Reportedly, there are no adverse effects on the chickens themselves, which lay eggs as normal.
The researchers say the findings 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.
“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 Prof. Helen Sang at The Roslin Institute, an animal sciences research institute at in Midlothian, Scotland, which is part of the University of Edinburgh.
Of course, there is already precedent for eggs and human therapeutics. Specifically, eggs are already used for growing viruses that are used as vaccines for influenza, for example. What makes this new approach distinctive is that the therapeutic proteins are encoded in the chicken’s DNA and produced as part of the egg white.
Other researchers have shown that genetically modified goats and rabbits can produce proteins like this in their milk. As the authors of the University of Edinburgh research note in a paper published in BMC Biotechnology, “The global market for protein drugs has the highest compound annual growth rate of any pharmaceutical class but their availability, especially outside of the US market, is compromised by the high cost of manufacture and validation compared to traditional chemical drugs. Improvements in transgenic technologies allow valuable proteins to be produced by genetically-modified animals; several therapeutic proteins from such animal bioreactors are already on the market after successful clinical trials and regulatory approval. Chickens have lagged behind mammals in bioreactor development, despite a number of potential advantages, due to the historic difficulty in producing transgenic birds, but the production of therapeutic proteins in egg white of transgenic chickens would substantially lower costs across the entire production cycle compared to traditional cell culture-based production systems. This could lead to more affordable treatments and wider markets, including in developing countries and for animal health applications.”
The BMC Biotechnology paper is titled “A chicken bioreactor for efficient production of functional cytokines.”
The team 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.
They say that just three eggs were enough to produce a clinically relevant dose of the drug. Given that 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.
Researchers note that they haven’t produced medicines for use in patients yet, but the study offers proof of principle that the system is feasible and could easily be adapted to produce other therapeutic proteins.
Protein-based drugs include antibody therapies such as Avastin and Herceptin that are widely used for treating cancer and other diseases. For proteins like the ones used in these kinds of drugs, 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.
Dr. Lissa Herron, who is leading the commercialization of this research at Roslin Technologies, said the team was excited to develop the technology to its full potential. She added it offers hope for research in animal health as well as human therapeutics.

Jeffrey Bouley

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