Parkinson's Patient Gets Gene Therapy
Daring Treatment Would Improve Symptoms, Slow Disease
Aug. 19, 2003 -- It's new. It's risky. And it might just work.
It's a new gene therapy for Parkinson's disease. Researchers today announced that a 55-year-old New York man is the first patient to get the experimental treatment.
"He's doing fine so far. It's been just over 24 hours and he has no fever -- he's eating well, walking well, and is joking with us," Michael G. Kaplitt, MD, PhD, tells WebMD. "I think probably there will be a two- to three-month window to see a treatment effect."
Kaplitt, a neurosurgeon at Weill Cornell Medical College in New York, developed the gene therapy in collaboration with Matthew J. During, MD, director of the CNS Gene Therapy Center at Thomas Jefferson University in Philadelphia.
The phase I clinical trial is designed to find out whether the treatment is safe. If there are no safety problems, three more patients will get the same dose of the gene therapy. The next four patients will get a higher dose, and four more patients will get an even larger dose. Dosages are based on what worked in animal studies.
To deliver the treatment, Kaplitt drilled a hole in the patient's skull. He then carefully infused billions of virus particles into a tiny part of the brain called the subthalamic nucleus or STN.
The hollowed-out virus particles are filled with two versions of a gene that essentially slows down brain cells. Brain degeneration in Parkinson's disease causes the STN to get overexcited. This leads to the abnormal movements, tremor, rigidity, and gait problems that make life miserable for Parkinson's patients. The gene therapy is designed to reverse this.
A Risky Business
The gene therapy is literally intended to change a patient's brain. In Parkinson's disease, the STN excites the brain. But after getting the new genes, the hope is that the STN will also be able to slow the brain down.
It's a delicate balance, says Robert Hauser, MD, director of the Parkinson's disease and movement disorder center at the University of South Florida in Tampa.
"In an ideal world, you would balance things out in the Parkinson's brain and get them back to normal," Hauser tells WebMD. "How do you get it exactly right? If you get it too negative, you get the opposite of Parkinson's disease -- the severe twisting, turning movements we call dyskinesia."
And that's just one issue. What if the virus spreads through the brain, slowing down normal brain functions? Because gene therapy is still a very new technique, many unexpected consequences are possible.
That's true, Kaplitt admits. But 15 years of preparatory work -- including rat studies published last year and still-unpublished monkey studies -- convince him that the risks are acceptable.
"We've tried to build in extra safety measures," he says. "But until you do this in an actual human being, there is a risk. There is still the possibility that we will make too much [brain-slowing signal]."
The same virus used to deliver the Parkinson's gene therapy was recently used to deliver a gene to the brains of children born with a rare, fatal birth defect. Kaplitt says the virus didn't spread throughout the brain but remained where it was put -- just as he saw in animal studies.
And even though he points out the risks, Hauser is enthusiastic about the gene therapy.
"I think it is a good idea," he says.