By Bradley J. Fikes
A diabetes drug developed by a San Diego biotech company from a venomous lizard’s saliva reduces Parkinson’s disease symptoms, according to a study published Thursday.
The placebo-controlled study of 62 patients found the drug, exenatide, provided statistically significant effectiveness in preserving motor control. It may actually slow down disease progression, although this has to be confirmed with more research.
For Parkinson’s patients, the trial represents stronger grounds to expect more effective treatments. For San Diego’s life science community, it represents another example of the benefits of original research and innovation.
The study was published in The Lancet by researchers led by Thomas Foltynie and Dilan Athauda, both of University College London in London, England. While the study wasn’t particularly large, with 62 patients, it was placebo-controlled, and is in line with a previous clinical study published in 2014.
Exenatide was found in Gila monster saliva by Dr. John Eng, an endocrinologist at Bronx Veterans Affairs Medical Center in New York. The venomous lizard, native to the Southwestern United States and northwestern Mexico, delivers excruciating pain with its bite.
San Diego’s Amylin Pharmaceuticals licensed the discovery in 1996. Further development yielded exenatide, sold under the brand name Byetta.
The drug became a hit, providing a major reason for Amylin’s 2012 purchase for $7 billion by Bristol-Myers Squibb. As for Amylin, the company was disbanded and no longer exists.
Exenatide/Byetta reduces insulin resistance in Type 2 diabetes, allowing for better control of blood glucose. There’s evidence that Parkinson’s disease is also related to problems with insulin signaling.
The new clinical study improves on the previous study because it is placebo-controlled, according to an accompanying commentary in The Lancet. But the study has limitations that prevent it from being considered definitive.
“Whether exenatide acts as a novel symptomatic agent or has neuroprotective effects on the underlying Parkinson’s disease pathology remains unclear, but Athauda and colleagues’ study opens up a new therapeutic avenue in treatment of Parkinson’s disease,” the commentary stated.
Christian Weyer, M.D., a former Amylin executive, said one of the most interesting parts of the study was exenatide’s potential for modifying the course of Parkinson’s disease. Weyer is now president of Chula Vista’s ProSciento, a clinical services provider.
Patients were measured on motor skills after getting 48 weeks of injections, either with exenatide or placebo. The treated group showed an advantage of 4 points on a 132-scale test, which was statistically significant.
Exenatide mimics the action of a hormone, and such drugs often show disease-modifying properties, said Weyer, who was Amylin’s Senior Vice President of Research and Development.
“It’s not conclusive that exenatide has the potential for disease-modification, but I was impressed by the fact that the endpoint of the test was in the off-medication period, so you actually assess whether there’s an effect even after the treatment had been stopped,” Weyer said.
Amylin had performed early preclinical research on exenatide for Parkinsons’ disease, Weyer said. The research was funded by a small grant from the Michael J. Fox Foundation.
In chronic diseases such as Type 2 diabetes and Parkinson’s, finding disease-modifying therapies is the “Holy Grail,” Weyer said.
“These are life-long diseases, and anything you can do to either delay or prevent the onset of the disease, or to slow its progression over a long period of time” has great benefit, Weyer said.
Insulin has many biological roles in the body, so it’s not surprising that an abnormal response to insulin could play a role in Parkinson’s disease as well as diabetes, Weyer said.