The whole area of immunotherapy for PD is new for me, so I did some reading to try to get a basic understanding. In the process I came across quite a good review article, which is also fairly recent (2015). It covers both active immunotherapy (injecting "manufactured" antigens) and passive immunotherapy (injecting "manufactured" antibodies). The active immunotherapy section includes a paragraph describing the work of AFFiRiS.
Immunotherapy in Parkinson’s Disease: Micromanaging Alpha-Synuclein Aggregation - IOS Press