The study will consist of an initial screening period of up to approximately 6 weeks to determine eligibility for enrollment per protocol defined inclusion and exclusion criteria. This will be followed by a Treatment period of 104 weeks (24 months), when Participants will return to clinic every 2 weeks for the first 4 weeks and every 4 to 13 weeks thereafter as per the assessment schedule. At all on-site study visits, study drug administration will be performed during the visit, and safety, PK, and/or biomarker samples will be collected according to the assessment schedule. During the treatment period, the participant will be randomised to receive by subcutaneous injection either Farabusen 300mg vs. placebo or Farabusen 150mg vs. placebo every two weeks. Participants and/or caregivers will be trained in injection administration at three sites: abdomen, upper arm, or front middle thigh. Self-administration by participant/caregiver will be possible at abdomen or front middle thigh but arm administration will be limited to caregiver.
During study visits we will perform procedures such as asking questions about your health and medications, physical exams, vital signs, electrocardiograms (ECG), Magnetic Resonance Imaging (MRI) scans (2 total), blood and urine samples