The focus on disease-modifying treatments and cures for Parkinson's disease (PD) has raised expectations for quantum leaps and overshadowed incremental gains that have been slowly achieved. Large multi-center clinical trials such as DATATOP and PRECEPT keep on generating new knowledge that is relevant to clinical care as well as experimental therapeutics. The largely unforeseen relationship between circulating uric acid and the occurrence and progression of PD was developed and confirmed in these clinical trials. Systematic follow-up of clinical trial cohorts after conclusion of the interventional phase provides added value that continues to inform about natural history, state and trait biomarkers, and genotype-phenotype relationships. These efforts are enhanced by data mining, public reporting, and timely sharing of data and biological samples.