This clinical trial is focused on studying Huntington’s Disease, a genetic disorder that causes the progressive breakdown of nerve cells in the brain. The study is testing a treatment called PTC518, which is taken as a tablet. The purpose of the study is to evaluate the long-term safety and effectiveness of PTC518 in people with Huntington’s Disease. The study will look at how the treatment affects levels of a protein called total huntingtin (tHTT) in the blood, which is associated with the disease.

Participants in the study will be randomly assigned to receive either the PTC518 tablet or a placebo, which looks like the treatment but does not contain the active substance. The study is designed to be double-blind, meaning neither the participants nor the researchers will know who is receiving the actual treatment or the placebo. This helps ensure that the results are not influenced by expectations about the treatment. The study will last for up to 24 months, during which participants will take the tablets and have regular check-ups to monitor their health and the effects of the treatment.

Throughout the study, various assessments will be conducted to monitor the safety of PTC518 and its impact on the disease. These assessments will include checking for any side effects, changes in vital signs, and physical examinations. Additionally, the study will measure changes in brain structure using a method called vMRI and evaluate specific protein levels in the blood and cerebrospinal fluid. The goal is to gather comprehensive data on how PTC518 affects the progression of Huntington’s Disease over time.