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Drug protects healthy cells in radiotherapy

Alok Jha

Scientists have found a drug which can protect healthy cells from radiation. The discovery could improve the effectiveness of radiation therapy in treating cancer and help prevent radiation sickness after exposure to a nuclear accident or attack.

Radiotherapy is an important tool in the fight against cancer but it has unpleasant side-effects, killing healthy cells in the bone marrow, gut and spleen. The radiation causes damage to the DNA of healthy cells, prompting them to kill themselves through a process known as apoptosis. The body uses this method to stop damaged cells from multiplying; tumour cells survive by switching off the apoptosis mechanism.

Lyudmila Burdelya, of the Roswell Park Cancer Institute in Buffalo, New York, led a team that investigated whether radiation-damaged healthy cells could be rescued by mimicking cancer cells. The new drug, CBLB502, works by activating the same mechanism used by cancer cells to switch off apoptosis. A single dose given to mice and monkeys just before a big dose of radiotherapy significantly reduced damage to gastrointestinal cells and prolonged the animals’ lives.

“The treatment rescued more than 87 per cent of mice from radiation-induced death. At this radiation dose, the most powerful previously described radioprotectants provided about 54 per cent protection or had no protective effect at all,” the researchers write in the journal Science.

In rhesus monkeys, injecting the drug up to 24 hours before a dose of radiation which would normally kill 70 per cent of the animals “delayed the onset of radiation-induced mortality by 10 days and increased the 40-day survival rate from 25 to 64 per cent.” The drug was also effective in mice when administered an hour after the radiation exposure, and the researchers reported no obvious side-effects. In a separate experiment, it was shown that the treatment of tumour cells by radiation was unaffected by the drug.

The researchers said the drug was mainly a way to make radiotherapy work better but thought it could be stockpiled as a preventive medicine in case people are exposed to radiation during a nuclear accident or as a result of a “dirty bomb” using radioactive material. — © Guardian Newspapers Limited, 2008

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