PREP and Parkinson disease: Interestingly, the most recentcompound that entered clinical trials, S17092, had no effect on thePPI-mediated functions of PREP when it was later evaluated in ourassays.17 The well-known peptide-like PREPinhibitor KYP-2047 (Figure 1) differs from S17092 in that it is also able to modulatethe PPIs of PREP.17 KYP-2047 has been shownto reduce αSyn aggregation and enhance autophagy to degradeαSyn aggregates in several in vitro and in vivo PD models,18−22 and most recently, to reduce Tau aggregates in vitro and in vivo.