Safety, Tolerability and Exploratory Efficacy of EC5026 in Parkinson's Disease (STEP Study)

The goal of this clinical trial is to learn if the oral drug candidate EC5026 is safe and targets the correct pathways to treat Parkinson's Disease in adults. It will also learn about the levels of drug that are achieved in blood and in the fluid surrounding the brain (spinal fluid). The main questions it aims to answer are: * Is EC5026 safe in adults with Parkinson's Disease? * What are the levels of EC5026 achieved after oral administration for 28 days? * What molecules or pathways does EC5026 target, and to what extent? In addition, although it is not one of the primary aims of the study, this clinical trial will also explore if oral administration of EC5026 improves the symptoms of Parkinson's Disease. Researchers will compare EC5026 to a placebo (a look-alike substance that contains no drug). Participants will: * Take EC5026 or a placebo every day for 28 consecutive days * Visit the clinic for frequent checkups, blood tests, spinal fluid tests, and questionnaires