This clinical trial is focused on studying Parkinson’s Disease, a condition that affects movement and can cause tremors, stiffness, and difficulty with balance and coordination. The study is investigating a new treatment called BIA 28-6156, which is an allosteric activator of the enzyme beta-glucocerebrosidase (GCase). This enzyme is important for breaking down certain substances in the body, and the treatment aims to help manage symptoms in people with Parkinson’s Disease who have a specific genetic variant in the GBA1 gene.

The purpose of the study is to evaluate how effective BIA 28-6156 is in slowing down the progression of motor symptoms in individuals with this genetic variant. Participants in the study will be randomly assigned to receive either the treatment or a placebo, which looks like the treatment but does not contain the active substance. The study will be conducted over a period of time, during which participants will take the medication in the form of a film-coated tablet by mouth. The study will monitor the safety and tolerability of the treatment, as well as how it is processed by the body.

Throughout the study, participants will be assessed using a scale called the Movement Disorder Society – Unified Parkinson’s Disease Rating Scale (MDS-UPDRS), which helps measure the severity of motor symptoms. The study aims to determine if BIA 28-6156 can delay the worsening of these symptoms compared to the placebo. This research is important for understanding potential new treatments for Parkinson’s Disease, especially for those with the GBA1 gene variant.