From the conclusion:
"Importantly, the dose response of oligomeric alpha-synuclein and HVA changes to nilotinib suggests that the dose administered may depend on the stage of disease to potentially halt PD progression."

I had a lot of trouble understanding this sentence, and I found the PNT article to be of no help in that regard.

Assuming I've understood it correctly, here is an alternative wording that might (or might not!) be clearer:
"The dose-dependent decrease in oligomeric alpha-synuclein levels (and increase in HVA/DOPAC levels) suggests that (to potentially halt PD progression) the stage-of-disease may dictate the appropriate dose of nilotinib to administer."

Anyway, it seems to me that there is still a lot of research to be done to establish the correct dose for each stage of the disease. This might well affect the prospects for a fast-track approval.

Hopefully, another write-up will appear (from AlzForum, SoPD blog, ...) and shed some more light.