By Ben Hirschler, August 21, 2009
LONDON (Reuters) - A genetically modified bacterium that turns into a drug-delivery vehicle in the presence of a type of sugar may offer a new way to treat bowel disease, British scientists said on Friday.
The new approach uses an engineered form of Bacteroides ovatus to deliver a human growth factor called KGF-2 directly to damaged cells in the gut -- but the process is only activated in the presence of xylan, a sugar that is rare in normal diet.
This means patients will be able to control their medication by ingesting xylan, perhaps in the form of a drink, after swallowing the freeze-dried bacteria in capsules.
"This is the first time that anyone has been able to control a therapeutic protein in a living system using something that can be eaten," said Simon Carding of the Institute of Food Research, who led the research.
Researchers aim to start clinical trials of their "sugar bug" drug in around 18 months, after successful tests in mice.
Inflammatory bowel conditions like Crohn's disease and ulcerative colitis affect around 0.5 percent of the population in rich countries and are notoriously difficult to treat.
Current therapies include a group of injectable drugs that block an inflammatory protein called tumor necrosis factor (TNF), such as Johnson & Johnson's Remicade, Abbott's Humira and UCB's Cimzia.
Carding and colleagues reported in the journal Gut that the treatment was effective in mice with colitis, reducing bleeding and accelerating healing, and he said he is confident it should also work in other bowel disorders.
"We have other strains of the bacteria that will deliver other therapeutic agents that will be effective in other forms of inflammatory bowel disease and also colorectal cancer," he said.
In the case of cancer, the British team is developing strains of bacteria that will produce proteins to restrict blood vessel growth in tumors.
Others are also researching bacteria-based drugs and Belgian biotech company ActoGeniX has a bowel drug in Phase II clinical tests. But Carding said his team's product was the first where dose could be controlled simply by eating a foodstuff.
