The UK's leading cancer charity yesterday welcomed work by British scientists who created a breed of genetically modified hens that can produce cancer-fighting medicines in their eggs. The research could slash the cost of producing drugs and potentially save the NHS millions of pounds.

Helen Sang, of the Roslin Institute in Edinburgh, where Dolly the sheep was cloned in 1997, genetically modified hens to lay eggs that contained complex medicinal proteins similar to the drugs used to treat multiple sclerosis, skin cancer and arthritis.

The hens have had human genes added to their DNA, which means human proteins are secreted into the whites of their eggs.

Working with the biotechnology firm Viragen and the British biotech company Oxford BioMedica, Dr Sang also showed that the proteins could be easily separated out of the eggs.

Herbie Newell, director of translational research at Cancer Research UK, said: "Anything that allows us to expedite the number of novel therapeutics that we can offer cancer patients and also potentially reduces the cost of their manufacture must be welcomed."

A spokesperson for the Multiple Sclerosis Society added: "This is an intriguing development and anything that has the potential to cut drug costs will be welcome in the current NHS financial climate. The challenge for researchers will, however, be realising this potential and turning this work into properly trialled treatments that can be used in humans."

The active ingredients of drugs are usually made in industrial quantities in bio-reactors containing a mixture of bacteria or other cells that have been modified to produce complex proteins. The process is expensive and time-consuming to set up, which in turn raises the price of the end product.

Dr Sang used the chickens in place of the industrial bio-reactors. She modified the gene in the hens that produces ovalbumin - a protein that makes up more than half of egg whites - so that it also produced specific medicinal proteins. The research is published today in the Proceedings of the National Academy of Sciences.

In a flock of 500 genetically modified chickens, Dr Sang found that all the egg whites from the hens contained miR24, a monoclonal antibody with potential for treating malignant melanoma and arthritis, and human interferon b-1a, an antiviral drug that closely resembles modern treatments for multiple sclerosis.

"Increasing global demand for ... pharmaceutical proteins has resulted in significant research being focused on development of alternative production platforms, including the use of [genetically modified] animals as bio-reactors," wrote the researchers.

Using farm animals to produce drugs is potentially faster, cheaper and more efficient than current industrial methods. The chickens used by Dr Sang, ISA browns, are a common breed that can produce up to 300 eggs a year.

The production of pharmaceutical proteins has been demonstrated previously in genetically modified mammals including sheep, goats, cattle and rabbits. Until now, however, the proteins have been difficult to extract and the ability to produce useful proteins vanishes after a few generations.

Researchers said that in the latest study, they had bred five generations of chickens and each one had produced good concentrations of drugs. In theory, they added, the technique could be used with a wide range of genes so that hens could produce many different drugs for a range of diseases, from Parkinson's to diabetes and other types of cancer.