Is exendin-4 the new hope for Parkinson's?

Hi all - a few years back, I read on another forum that apparently exendin-4, which is currently used to treat diabetes might also help patients with PD. I remember someone saying that pharma companies weren't interested in developing it, as it had potential to halt disease progression and all they want is to treat our symptoms - not cure us! In any case, according to a book that I have come accross on kindle, exendin-4 might just be the disease-modifying treatment we have all been waiting for. Let me know what you think if you've heard about exendin-4 or read the book - I'd be keen to hear your thoughts.