GENERATION HD2. A Study to Evaluate the Safety, Biomarkers, and Efficacy of Tominersen Compared With Placebo in Participants With Prodromal and Early Manifest Huntington's Disease.

Key Inclusion Criteria

-Huntington's disease (HD) gene expansion mutation carrier status with a CAP score of 400-500 inclusive

Either:

• Prodromal HD (defined as DCL 2 to 3, Independence Scale (IS) ⩾70, and ⩾TFC8); or

• Early manifest HD (defined as DCL 4, Independence Scale (IS) ⩾70, and ⩾TFC8);

• Total body weight > 40 kg and a body mass index within the range of 18-32 kg/m2

• Study Companion

Key Exclusion Criteria

• Current or previous use of an ASO (including small interfering RNA) or any HTT lowering therapy (including tominersen)

• Anti-platelet or anticoagulant therapy within 14 days prior to screening or anticipated use during the study, including, but not limited to, aspirin (unless

• History of gene therapy, cell transplantation, or brain surgery

• Hydrocephalus

• Pregnancy or breastfeeding, or intention of becoming pregnant during the study or within 5 months after the final dose of study drug

• History of attempted suicide or suicidal ideation with plan (i.e., active suicidal ideation) that required hospital visit and/or change in level of care within 12 months prior to screening