Gene therapy has been hailed as the future of medicine, but for Michael Kaplitt, the future appears to be now. Kaplitt, a neurosurgeon at New York–Presbyterian Hospital/Weill Cornell Medical Center, is using gene therapy to help patients in the advanced stages of Parkinson’s disease, the chronic, progressive neurological disorder that afflicts some 1 million Americans.
Before last year, when Kaplitt began administering the treatment, advanced Parkinson’s sufferers were commonly treated with deep brain stimulation, which uses electrodes implanted in the brain to regulate neurological activity. Deep brain stimulation, says Kaplitt, is highly effective at reducing the tremors that characterize Parkinson’s. “We have a lot of happy patients,” Kaplitt says. But deep brain stimulation requires surgical maintenance of batteries and wires, which can get infected and need to be repeatedly reprogrammed. The goal of gene therapy, says Kaplitt, “is to re-create areas of the brain more naturally.”
In Kaplitt’s procedure, he injects a synthetic gene called GAD into the sub-thalamic nucleus region of the brain to quiet the cells responsible for Parkinson’s debilitating effects. (In addition to tremors, the disease can cause muscle stiffness, impaired balance, and speech difficulties.) The gene is injected inside an engineered virus known as an adeno-associated virus, which acts as a sort of courier service. “Viruses transfer genes from one cell to another,” says Kaplitt. “It’s very efficient.” The procedure takes four to five hours, is done with a local anesthetic that allows the patient to remain awake, and requires minimal recovery time. Inside the brain, the gene produces a chemical called GABA, which is critical for maintaining normal motor activity. “This is the first time that anybody has put genes into an adult human’s brain cells with the purpose of changing how the cells function,” Kaplitt says.
It’s too early to draw conclusions about the effectiveness of gene therapy—the treatment is still in the trial phase—and Kaplitt is quick to point out that gene therapy is not a cure. “It represents a stepping-stone,” he says. But at least one early sign indicates the treatment may improve patients’ lives. The first of Kaplitt’s five patients so far appears to have benefited significantly. “My tremors are almost totally gone,” says Nathan Klein, a 56-year-old television producer who underwent treatment last August. Although he must still take medication to control his symptoms, Klein says that even without the medicine, he is “25 percent” better than he was before being treated. His walking and speaking have also improved dramatically, he says, and he now has the energy to go out with his family more often. “But they’re teenagers,” he says of his children. “They don’t want to do anything with their parents anyway.”