Update on GENERATION HD2 enrollment and study status

Dear Huntington’s patient community leaders,

We appreciate your request for timely and relevant updates about our Huntington’s Disease (HD) research efforts. Today, we are pleased to share a status update on the GENERATION HD2 Phase II study for individuals with early or very subtle symptoms of HD (NCT05686551). This information has been shared with study investigators and at invited HD scientific and family events.

Study progress and plan to complete enrollment

We thank the HD community and our study site network for their ongoing support. Recruitment into the study has been steady worldwide, and we plan to complete enrollment by the end of the year. Currently, more than 80% of the approximately 300 planned participants have been enrolled.

The GENERATION HD2 study aims to evaluate the efficacy, safety, and biomarkers of the investigational drug tominersen in individuals aged 25 to 50 with early or very subtle symptoms of HD. The study is being conducted in 15 countries: Argentina, Australia, Austria, Canada, Denmark, France, Germany, Italy, New Zealand, Poland, Portugal, Spain, Switzerland, the UK, and the US.

Planned data check: Data monitoring committee supports study continuation

From the start of the study, we established an external, independent data monitoring committee (iDMC) to ensure the safety of participants by regularly reviewing data and the balance of benefit and risk. This committee reviews data approximately every 4-6 months and provides recommendations to continue, modify or stop the study.

The iDMC in August 2024 recommended continuing the study unchanged after reviewing data on clinical efficacy, safety and biomarkers.

We are extremely grateful to all participants, family members, and study sites that have supported the study and its research aims. For anyone interested in learning more about the GENERATION HD2 study, please speak to an HD specialist. Additional information, including study locations, can be found on clinical trial registries such as clinicaltrials.gov or ForPatients.Roche.com.

Sincerely,

Mai-Lise Nguyen, on behalf of the Roche & Genentech HD team Global Patient Partnership, Neuroscience and Rare Diseases M-XX-00018766 | Page 1/1