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Gene therapy for Parkinson's: success in a mid-stage trial

UPDATE: The study is available here.

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Promising results of a randomized, double-blind, Phase 2 trial in patients with Parkinson's disease may help resurrect a therapeutic approach that had fallen on hard times.

Parkinson's disease is a chronic condition in which gradual loss, for reasons not well understood, of a cluster of nerve cells in the brain leads to increasingly hobbled movement. Early on, Parkinson's is usually well controlled by drugs. But as it progresses, drug treatment can often fail. Millions of patients await more-lasting relief.

One approach to treating disease in general is to boost sick cells' levels of proteins that, for whatever reason, appear to make the cells work better, or stay alive longer.

A way to do that would be to squirt significant amounts of the protein in question into the appropriate tissue or the blood, If the protein manages to keep from being chopped to pieces by roving molecular scissors that roam through blood and tissues), one can hope it will then squeeze itself through the targeted cells' only somewhat permeable outer membranes. Having run this triathlon, maybe it will still be in working condition. And maybe not. (Would you be?)

There's another way to get the desired effect, although it too has its difficulties.

As we know, the recipes for proteins, known as genes, are pieces of DNA that dot our chromosomes. Gene therapy involves the introduction into cells of a new and, putatively, helpful piece of DNA by means of, say, a virus that has been bioengineered to be harmless but retains the ability to invade cells.

With the 1999 death of young Jesse Gelfinger in a gene-therapy trial, clinical studies of this method slowed to a crawl.

The just-reported trial represents the first confirmation, albeit still tentative, of gene therapy's efficacy in a randomized double-blind clinical trial - the so-called gold standard of drug development - of Parkinson's patients. Stanford neurologist Kathleen Poston, MD, and brain surgeon Jaimie Henderson, MD, participated in this multi-center trial, in which 23 patients received a virally delivered payload: a gene encoding an enzyme that, in animal studies, appeared beneficial. Another 22 patients received "blanks" - viruses with no such genetic payload.

The study was published in Lancet Neurology. I'll post a link as soon as it becomes available.

Poston and Henderson are now recruiting patients for another gene-therapy trial for Parkinson's, featuring the viral delivery of a different gene. The Michael J. Fox Foundation has kicked in $2.5 million, and the National Institutes of Health $5.4 million, for this new study. (People interested in participating in this trial should contact Sandra Dunn at 650-724-8278.)

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