Scientists look to cold virus to fight tumors

The technology is not new: Scientists are using a disabled cold virus to ferry a tumor-destroying gene into patients with cancers of the head and neck.

But researchers’ excitement over the widely reported experimental treatment is typical of renewed optimism for a field that has suffered serious setbacks in recent years.

Last week, some 2,000 scientists from around the world gathered in Seattle for the 10th annual meeting of the American Society of Gene Therapy.

“These are all early days for these studies. Some will work, some won’t,” said Dr. Theodore Friedmann, a geneticist at the University of California, San Diego, who heads the society.

“But many more people are being helped. … It’s time to recognize what has been achieved.”

The treatment for head and neck cancers is so promising that it is now in final trials in China. But gene therapy, once hailed as a potential major medical breakthrough, has had serious missteps, especially in the past decade.

Among them, an 18-year-old with a rare metabolic disorder died in 1999 at the University of Pennsylvania of a severe immune reaction to a gene-carrying virus injected to correct the disease. The incident prompted federal investigations and cast a pall over the entire technology.

Gene therapy also has been slow to develop in part because it has been hard to find a virus or other carriers that take genes into the human body without causing immune reactions.

For years, researchers focused on adenoviruses, a class of cold viruses, that were altered so they would not cause respiratory diseases. But the body still reacted to them. More recently, scientists have used another type, called adeno-associated viruses, that are better accepted by patients’ immune systems.

Several hundred proposed gene therapies have failed over the nearly two decades that the technology has been tried in humans.

But at least one qualified success was reported: In 2002, 10 boys in France were cured of a rare immune-deficiency disorder. Though three of the children developed a leukemialike disease from the treatment – and one died – the others are well. The technique has since been altered to prevent the side effect.

Today, scientists are still trying to replace faulty genes to fight diseases such as cystic fibrosis and sickle-cell anemia. But now they’re also trying it with other diseases that may not have such a strong genetic basis, including cancer, heart disease, Parkinson’s disease and arthritis.

Dr. Philip Mease of Swedish Hospital Medical Center in Seattle has been researching a promising therapy for arthritis in patients whose critical joints aren’t adequately helped by drugs.

In Mease’s research, injected genes make a protein that reduces a substance in the joint that causes inflammation. Mease says early results show the treatment is safe enough to proceed to additional trials.

Elsewhere, experimental treatments are trying to boost immunity against prostate and lung cancers. Another seeks to ease angina, or heart pain, by stimulating growth of new arteries to feed the heart.

Still other research is aimed at replenishing a brain chemical depleted in people with Parkinson’s disease. And scientists are hoping to use gene therapy to halt the progression of macular degeneration, which causes blindness.