Here's my briefing notes based on the referenced Medical Express article (the PNAS paper is behind a pay-wall):

In a rat model of Parkinson's it was found that:
- Nurr1, a protein found in the brain, "protects the brain's ability to generate dopamine neurons";
- activating Nurr1 in rats eliminated all symptoms of Parkinson's.

Nurr1 is activated by existing FDA approved anti-malarials, chloroquine and amodiaquine.

There would seem to me to be a good case for going ahead with clinical trials on the existing drugs. But no, they want to modify the drugs first, before carrying out clinical trials. Why?

Interestingly, there's a lot of claims in PwP sites around the web that quinine relieves PD, and a few claiming that it causes it.

John