New HIV study shows promise

Limited trial reveals no side effects in therapy using AIDS virus against itself

November 08, 2006|By Jamie Talan | Jamie Talan,NEWSDAY

Scientists at the University of Pennsylvania have designed a gene therapy strategy to treat HIV, the precursor to AIDS, and a pilot study on five patients resistant to current therapies suggests that it may work.

"It's very heartening," said one of the patients in the study, published this week in the Proceedings of the National Academy of Sciences. "The goal of the trial was safety. I didn't expect to see a benefit."

The 44-year-old Pennsylvania man signed on to the experimental study in 2003, when his treatment options were limited and the medicines he was taking were no longer as effective.

This is the first gene therapy strategy for AIDS that uses a modified version of the virus itself - one that can invade cells but does not replicate. Its success has set the stage for further research with more patients.

"It's a promising start," said Bruce Levine of the University of Pennsylvania. "The hope is to increase immune function and slow the spread of the virus."

In prior studies, other viruses have been used as vectors to deliver genes into cells but have triggered side effects, including cancers. A vector works like a missile to deliver genes, or medicines, into the body.

The side effects with other viral vectors led Levine and Carl June, also of the University of Pennsylvania School of Medicine, to consider a human AIDS virus as a vector. They worked with a company called Virxys in Gaithersburg to modify the virus by disabling its replication machinery.

With these modified viruses in hand, they recruited five patients who were no longer responding to the traditional AIDS cocktails to participate in a pilot study to test the therapy's safety. Doctors removed infection-fighting immune cells from these patients - they are found in white blood cells - and mixed them with the modified virus. They grew the cells in the lab and then infused them back into the patients.

There were no side effects from the infusion, and four of the patients showed a positive response - a lowering of viral load. One patient had a dramatic response - his viral load measures dropped 96 percent, from 54,100 three years ago to 1,930 last January.

"It's an important step forward," said Dr. Mark Kay, a professor of genetics and pediatrics at Stanford University, who did not work on the study. "I would be cautiously optimistic about the results. It requires further study with more patients."

Normally, HIV will deplete the patient's CD4 immune cells and leave the body unable to fight infections that are easily fended off in healthy people. It was hoped that the modified virus would put a monkey wrench into the viral replication system and stop the AIDS virus from reproducing.

These particular CD4 immune cells are like the quarterback of the immune system. They coordinate the body's immune response to infection.

The patients will be watched over the next 12 years.

"This is the first time that we tried anything like this," said Levine. "It would be dramatic if it was replicated in a larger study."

He said many AIDS patients can't tolerate the standard cocktail therapy or it isn't as effective over time. The scientists are now expanding the study to include as many as 25 patients.

Jamie Talan writes for Newsday.

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