An Extension of SKY-0515 in Participants With Huntington's Disease

The goal of this clinical trial is to test if the drug SKY-0515, an oral medication, can lower harmful proteins linked to Huntington's Disease (HD) and improve the symptoms of participants with HD. This study includes men and women aged 25 and older who have HD confirmed by genetic testing and meet certain requirements for physical ability and independence.

This is an OLE study to investigate the long-term safety, tolerability, and efficacy of SKY-0515 administered orally in participants with HD. To be eligible for this OLE study, participants must have completed dosing in a prior SKY-0515 treatment study and meet eligibility criteria for this study at an approved clinical study site. The study is comprised of an enrollment visit, a treatment period, and a follow-up visit. Throughout the study, participants will be evaluated as specified in the Schedule of Activities. At the enrollment visit (which may be the same as the last treatment visit of the prior study), participants will be consented to enter the OLE study and initiate open label treatment with 9 mg tablets of SKY-0515. Open label SKY-0515 will be self-administered daily (QD).

Inclusion Criteria: * Must have completed treatment in a prior SKY-0515 treatment study and, in the opinion of the Investigator, have been compliant with the prior SKY-0515 treatment protocol study procedures. * Must be able and willing to meet all study requirements in the opinion of the Investigator including: * Participants must be able to tolerate blood draws * Willing and able to comply with all scheduled visits, treatment plans,laboratory tests and other study procedures * Women who can have children must have a negative pregnancy test before starting and use two types of birth control during the study and for 30 days after the last dose of the study drug. * Men must agree to use birth control during the study and for 90 days after the last dose. Exclusion Criteria: -Have any other conditions that, in the opinion of the Investigator or Sponsor, would make the participant unsuitable for inclusion, or could interfere with the participant participating in or completing the study.