The goal of the research study is to see if NEU-411 (1) will help prevent or slow the worsening of LRRK2 driven Parkinson's Disease (PD) and, (2) is safe. This study will also determine how your body processes NEU 411 and what NEU-411 does to your body. The study doctor will discuss with you whether you are eligible to be part of this study. As part of this study, you will receive either NEU-411 or placebo (inactive substance). The study drug is in tablet form and is taken by mouth. The study will last about 67 weeks. You will come in for 19 visits. In addition to in-person visits with the study team, you will be required to complete daily tests using a smartphone and occasionally be asked to wear a smartwatch continuously for 1-week periods. These technologies will be provided to you for use during the duration of the study and you will be trained on how to perform these activities. The NEU-411 is investigational and has not been approved by the US Food and Drug Administration as well as the investigational Companion Diagnostic (CDx).

This study will help determine the safety and effectiveness of BIIB122, compared to placebo (an inactive substance), in people with early-stage Parkinson's disease. The use of BIIB122 in this study is investigational. "Investigational" means that the study drug is currently being tested and is not approved by the U.S. Food and Drug Administration (FDA) or any other health authorities around the world for treating people with PD. The study is expected to last a minimum of 1 year to a maximum of 3 years. You may or may not receive direct medical benefit from participating in this study. Your condition may get better, worse, or stay the same. The information obtained from this study, however, could help other patients with your disease in the future.