Drug hope for cancer treatment

It is hoped the drugs will aid radiotherapy

A new drug that could revolutionise the impact of radiotherapy on cancer has been developed by scientists.

The drug - created by the Cancer Research UK's clinical unit at Newcastle University - has been designed to destroy the protection enjoyed by cancer cells.

Radiotherapy kills cancer cells by causing damage to DNA - but the cell's own repair process manages to limit the effect.

The new drug disables the DNA's ability to mend damage caused by radiotherapy, according to research leader Professor Hilary Calvert.

Cell rescue

Professor Calvert was speaking at Cancer Research UK's first annual conference in Kenilworth, Warwickshire on Monday.

He said: "Our DNA is damaged all the time during life's daily routine.

"One cell sustains about 30,000 incidents of DNA damage every day through the oxygen and chemicals circulating in the body.

"Therefore the DNA damage repair process is invaluable and keeps us from dissolving into a blob of jelly."

The downside is that the DNA repair kit also comes to the rescue of cancer cells when they are under attack.

Clinical trials

This has led scientists to search for a weapon to prevent repairs from working on tumours.

The most promising prospect is a class of drugs which inhibit the actions of the DNA repair enzymes knows as Poly (ADP-ribose) polymerases (Parps).

In pre-clinical studies, researchers have found these drugs are highly effective at sensitising cancer cells to radiotherapy.

Professor Calvert says one of the problems with radiotherapy - which is the most common way of treating cancer apart from surgery - is that the dose needed to kill large tumours is often too toxic to be sustained by the body.

He said: "We hope the Parp inhibitor will prove an effective radiosensitiser which would be a huge benefit to cancer patients."

Clinical trials of the drug are expected to start soon, but it could be several years before any drug could be licensed for general use.