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Drug protects cells from radiation

Friday 11 April 2008

A drug that protects healthy cells from radiation as been found, The Guardian reports. The drug “could improve the effectiveness of radiation therapy in treating cancer and help prevent radiation sickness after exposure to a nuclear accident or attack,” the newspaper adds.

The story is based on a study in mice and monkeys of a new drug called Protectan CBLB502. These findings will be of interest to the scientific community and mark the first steps in the development of the drug for use in humans. If the results of the study can be reproduced in people who receive radiotherapy for cancer, then they could reduce the side effects of treatment. However, the drug’s use, dosing and safety in humans will need to be assessed first.

Where did the story come from?

Dr Lyudmila Burdelya from the Roswell Park Cancer Institute in Buffalo, New York and colleagues from around the US carried out this research. The study was funded by grants from the National Institutes of Health, NASA, the Defense Advanced Research Projects Agency and Cleveland BioLabs, a drug discovery and development company that owns the rights to this compound and has a consulting relationship with some of the authors. It was published in Science , a peer-reviewed journal.

What kind of scientific study was this?

This was a report of a series of laboratory studies conducted in mice and monkeys. The protein Protectan CBLB502 was extracted from a bacteria and was investigated to see if it could protect the animals from the lethal effects of total-body irradiation. When the DNA in normal cells is damaged by radiation, a programmed process of cell death, called apoptosis, is set off to prevent the damaged cells from multiplying. The drug works by activating a protein that stops the cell from initiating this process.

To test whether the drug was effective, the researchers divided the animals into several groups. The many active groups were given the drug at various doses and timings. A single control group was given a painkiller. The researchers injected the drug before or after the animals were exposed to various doses of gamma irradiation. They then compared the time it took the mice to die in the treated and control groups. The researchers also examined various cellular details of the radiosensitive tissue, gut and bone marrow after death.

What were the results of the study?

The researchers found that mice and monkeys injected with the drug between 45 minutes and 24 hours before being subjected to the normally lethal radiation were more likely to survive or live longer than untreated animals. The drug extended survival in some of the groups from seven to 12 days.

The authors say they also examined a group of the animals that had been given cancers and were being treated with radiation, as if they were receiving radiotherapy. In these animals, they looked at the gut and bone marrow tissue under the microscope following the radiation experiments. They found that the drug did not appear to decrease the sensitivity of the mice to the treatment effects of radiation. This means that, although the drug stopped the mice from dying because of the radiation, the radiation still reduced tumour growth. The researchers say that this is significant because, if the drug were used alongside radiotherapy, it would be important that it did not reduce the effectiveness of treatment.

What interpretations did the researchers draw from these results?

The researchers suggest that their results demonstrate that this drug may be theoretically of value when given alongside cancer radiotherapy. The drug might also protect or reduce the effects of radiation in times of radiation emergencies. Separate comments in the journal suggest that such emergencies could include fallout from a nuclear disaster, such as Chernobyl, or the effects of a terrorist bomb.

What does the NHS Knowledge Service make of this study?

This is a preliminary laboratory study that tested the effects of a biological agent which shows promise for future use. However, any implication that this chemical might be effective as a drug for use in humans should be considered with caution. Its effects have not been tested yet in humans, but the experiments in non-human primates, such as monkeys, are a start. More studies are in the pipeline and will be needed before the safety, particularly in the long term, and value of this drug for use in humans is known.

Sir Muir Gray adds...

All treatment can do harm as well as good; any development that minimises the harm improves the benefit to harm ratio.

Analysis by Bazian
Edited by NHS Website

Links to the headlines

Drug 'could block radiation damage’.

Channel 4 News, 11 April 2008

Drug to protect against radiation.

BBC News, 11 April 2008

Drug that protects against radiation effects.

The Daily Telegraph, 11 April 2008

New drug can protect healthy cells during radiotherapy.

The Guardian, 11 April 2008

Links to the science

Burdelya LG, Krivokrysenko VI, Tallant TC, et al.

An Agonist of Toll-Like Receptor 5 Has Radioprotective Activity in Mouse and Primate Models.

Science 2008; 320:226-230