Safety, Tolerability, and Pharmacokinetics of Single Doses of <scp>ABBV</scp> ‐916, an Anti‐Amyloid Antibody, in Healthy Participants

Amyloid-beta (Aβ) plaque brain clearance is one of the promising disease-modifying treatment approaches to slow cognitive decline in Alzheimer's disease (AD). ABBV-916, an anti-amyloid antibody, was being developed as an early AD disease-modifying treatment. A phase 1, randomized double-blind, placebo-controlled single ascending dose (SAD) study investigated the safety, tolerability, pharmacokinetics (PK), and immunogenicity of ABBV-916 in healthy participants. Five groups of participants were enrolled and randomized 6:2 to receive ABBV-916 (100, 300, 1000, or 3000 mg) or placebo by intravenous (IV) infusion or subcutaneous (SC) injection (300-mg dose only). After dosing, participants were followed for 20 weeks for assessments. Cerebrospinal fluid (CSF) samples were collected after dosing 1000 mg IV for determination of ABBV-916 levels in the CSF. ABBV-916 single doses up to 3000 mg were well tolerated in healthy participants. No clinically significant laboratory findings, amyloid-related imaging abnormalities, or serious adverse events were reported. The ABBV-916 PK profile exhibited dose-related increases in maximum concentration and area under the plasma concentration-time curve with terminal elimination half-life ranging from 29 to 40 days across the cohorts. The estimated absolute bioavailability after SC dosing was 51%. The average CSF-to-serum partition ratio was 0.12% (range 0.10%-0.21%). Positive anti-drug antibody was detected in < 7% of participants, which was transient, at low titer, and did not affect ABBV-916 PK. This study demonstrated desirable safety, tolerability, and PK profile of ABBV-916 after single-dose administration in healthy participants. The data supported further evaluation of ABBV-916 multiple IV and SC doses in patients with AD.