Test found to target cancer drugs

WASHINGTON - A quick genetic screen may be able to tell doctors which lung cancer patients will benefit from new, targeted cancer drugs that have dramatic effects but only in a few people.

US researchers have found a specific DNA mutation in people who were virtually cured of their cancer by a new drug called Iressa, made by AstraZeneca.

Iressa has excited doctors because it is the first drug to work really well against lung cancer. Most patients suffering from lung cancer are killed by the disease, which is the biggest cancer killer in most of the world.

Two teams at Harvard Medical School in Boston and associated hospitals found the mutation in a gene called EGFR, which controls a protein called epidermal growth factor receptor. This in turn puts the brakes of cell growth.

In non-small cell lung cancer, EGFR is mutated and the cells proliferate out of control to form a deadly tamer. Non-small cell lung cancer accounts for about 85 per cent of all cases of lung cancer.

Iressa, known generically as gefitinib or ZD1839, works wonders for only about 15 per cent of lung cancer patients.

To find out why, the two teams tested the tumours of lung cancer patients who had been helped by Iressa and compared them to the tumours of patients who had not been helped.

"We obtained samples of cancer from patients who had been treated with Iressa and had dramatic responses," said Dr William Sellers of Harvard's Dana-Farber Cancer Institute.

"In every case we found a mutation in this EGFR gene. In the cases where there was no response, there was no mutation.

"People have not understood how Iressa is working or who it should be deployed in. This gives us a major clue."

"Mutations were more frequent in women, in Japanese patients, and in patients with adenocarcinoma," said Dr Bruce Johnson of Brigham and Women's Hospital and Harvard, whose team did a smaller but similar study.

- REUTERS