left the field altogether. It wasn’t until fairly recently that sentiment shifted, catalyzed by better delivery technologies and encouraging early clinical data. There is one gene therapy, from UniQure, that is approved in Europe. BlueBird Bio (NASDAQ: [[ticker:BLUE]]) has become a Wall Street darling over the past year because of indications a gene therapy it’s developing might help reverse a devastating blood disorder, beta-thalassemia (Genzyme, incidentally, helped Bluebird along when it contributed to a $35 million financing for the company when it was known as Genetix Pharmaceuticals).
Startups like Voyager, Spark Therapeutics, Audentes Therapeutics, and others have emerged. Large companies like Pfizer, Bayer, Celgene, and Biogen Idec are placing bets with startups and research institutions in the space.
None of those companies, however, have been making broad gene therapy bets in neuroscience. Genzyme is changing that with its deal today. It’s a risky one, for sure: Diseases like Parkinson’s have frustrated scientists for decades, because there is so much that is still unknown about the underlying biology. No gene therapy for a neurological disorder has ever even made it to a Phase 3 trial. Voyager aims to effectively deliver these therapies by injecting them directly either into the spine or brain; Safety issues are always a risk.
[Updated with comments from Paul] But the two companies believe they can make it work. Paul says Voyager has seen positive signs in preclinical studies in large animals that it can deliver these genes “up and down the spinal cord” to the motor neurons that are involved in many of the diseases it’s targeting.
Paul also points to a few potential advantages of delivering gene therapies into the spine or brain. First, he says those sites are “immunologically privileged,” which means gene therapies delivered there might be less likely to provoke an immune system attack. Secondly, Paul says, nerve cells don’t divide and grow, so an AAV gene therapy delivered to them could last as long as the cell lives. By comparison, a gene therapy delivered with an AAV to cells that grow and divide might wear off sooner. That’s the kind of thing that can lower the value proposition of gene therapy.
“We don’t think we have that problem, at least based on animal and some limited clinical data,” Paul says.
That’ll have to be proven in trials, of course. But Paul is optimistic.
“I don’t want to trivialize the challenges; there are going to be challenges here,” he says. “[But] we think if we can get the gene to the right place, we should have a therapeutic effect.”
