PT - JOURNAL ARTICLE AU - Carmen Castrillo-Viguera AU - Spyros Chalkias AU - Patrick Burkett AU - Shuang Wu AU - Huaihou Chen AU - Katie Harrison AU - Carol Yurgalevitch AU - Samantha Budd Haeberlein TI - EMBARK: A Phase 3b, Open-Label, Single-Arm, Safety Study to Evaluate the Long-Term Safety and Efficacy of Aducanumab in Eligible Participants With Alzheimer’s Disease (2448) DP - 2021 Apr 13 TA - Neurology PG - 2448 VI - 96 IP - 15 Supplement 4099 - http://n.neurology.org/content/96/15_Supplement/2448.short 4100 - http://n.neurology.org/content/96/15_Supplement/2448.full SO - Neurology2021 Apr 13; 96 AB - Objective: We describe the design of EMBARK, a Phase 3b re-dosing study of aducanumab in participants with Alzheimer’s disease (AD).Background: Aducanumab is a human monoclonal antibody selective for aggregated amyloid beta. On March 21, 2019, all aducanumab clinical trials were terminated following a pre-specified futility interim analysis of the Phase 3 studies, EMERGE and ENGAGE. Further analyses of the Phase 3 studies were conducted post-futility announcement using data from all randomized and dosed participants collected through April 1, 2019 with data after March 20, 2019 censored for efficacy analysis. In this final dataset, EMERGE met the pre-specified primary and secondary endpoints. Post-hoc analyses of data from a subset of patients exposed to high-dose aducanumab in ENGAGE support the findings of EMERGE.Design/Methods: EMBARK is an open-label, single arm clinical safety study (NCT04241068) with a 24-month treatment period assessing the long-term safety and efficacy of aducanumab in participants with AD who were actively participating in the aducanumab clinical studies PRIME, EVOLVE, EMERGE, or ENGAGE at the time of discontinuation.Participants will be titrated to receive 10 mg/kg aducanumab by intravenous infusion every 4 weeks. The study includes an approximately 8-week screening period, a 100-week treatment period and an 18-week safety and follow-up visit after the last dose.The primary objective of EMBARK is to evaluate the long-term safety and tolerability of aducanumab. The primary endpoints are number of participants with adverse events (AEs), serious AEs, AEs leading to treatment discontinuation or study withdrawal, amyloid-related imaging abnormality-edema or amyloid-related imaging abnormality-hemorrhage or superficial siderosis, and number of participants with anti-aducanumab antibodies.Results: EMBARK is currently enrolling.Conclusions: EMBARK is expected to be one of the largest clinical trials in AD, with a planned enrollment of 2400 participants. EMBARK will provide further information on the long-term safety and efficacy of aducanumab.Disclosure: Dr. Castrillo-Viguera has received personal compensation for serving as an employee of Biogen. Dr. Castrillo-Viguera has received stock or an ownership interest from Biogen. Dr. Chalkias has received personal compensation for serving as an employee of Biogen. Patrick Burkett has received personal compensation for serving as an employee of Biogen. Patrick Burkett has received stock or an ownership interest from Biogen. The institution of Patrick Burkett has received research support from NIH. Shuang Wu has nothing to disclose. Huaihou Chen has nothing to disclose. Katie Harrison has received personal compensation for serving as an employee of Biogen. Katie Harrison has received stock or an ownership interest from Biogen. Carol Yurgalevitch has received personal compensation for serving as an employee of Biogen. Carol Yurgalevitch has received stock or an ownership interest from Biogen. Samantha Budd Haeberlein has received personal compensation for serving as an employee of Biogen. An immediate family member of Samantha Budd Haeberlein has received personal compensation for serving as an employee of Alkermes. Samantha Budd Haeberlein has received stock or an ownership interest from Biogen.