It’s double-blind or nothing when it comes to phase III clinical trials. Although placebo groups are absolutely vital to the clinical validity of medical treatments, a recent article in The Lancet has me thinking about the ethics of treating desperate patients with saline.
The subthalamic nucleus is overactive in people with Parkinson’s disease, presumably because it loses GABAergic input from the globus pallidus. Subthalamic nucleus lesions improve Parkinson’s disease symptoms. Kaplitt et al. generated a gene therapy agent that would silence but not destroy subthalamic nuclei neurons. They inserted glutamic acid decarboxylase (GAD), the enzyme responsible for GABA production, into a viral vector and injected it into subthalamic nuclei of people with Parkinson’s disease. In their phase I trial in 12 patients, the authors showed that their therapy was safe and virtually side-effect-free. Unlike most phase I trials, the authors also showed that their treatment was effective: intra-thalamic injections of the GAD agent reduced Parkinson’s symptoms.
That’s great news for a possible new treatment for Parkinson’s disease. But it also means that at some point soon, people with advanced Parkinson’s symptoms will volunteer for brain surgery and a 50% chance at treatment. Some would argue that even placebos have their upside, and I certainly understand their importance. I also understand that the patients who volunteer for these studies are often at the end of their medical ropes and are willing to roll the dice. I just feel for the folks who wake up 6 months after surgery and realize that their symptoms haven’t improved.