<scp>ALZ</scp> ‐801 prevents amyloid β‐protein assembly and reduces cytotoxicity: A preclinical experimental study

Abstract

Abstract Alzheimer's disease (AD) is the most prevalent age‐related neurodegenerative disorder, mainly characterized by amyloid β (Aβ) accumulation in the brain. Numerous new agents are currently undergoing clinical trials as disease‐modifying therapies (DMTs) targeting Aβ. ALZ‐801 is a promising candidate DMT for AD, with a phase 3 trial of ALZ‐801 ongoing specifically for apolipoprotein E (APOE) ε4 homozygous patients with early‐stage AD. This study aimed to examine the effects of ALZ‐801 on Aβ assembly and explore its toxicological profile. Thioflavin T (ThT) assays and two imaging modalities—transmission electron microscopy (TEM) and high‐speed atomic force microscopy (HS‐AFM)—were used to evaluate ALZ‐801's effects on Aβ assembly. To assess the effect of ALZ‐801 on Aβ 42 ‐induced cytotoxicity, 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assays and lactate dehydrogenase (LDH) assays were performed. ThT assays revealed increased lag time and decreased fluorescence in the presence of ALZ‐801, confirming inhibition of Aβ 42 fibril formation, as confirmed by TEM. Real‐time observation using HS‐AFM revealed that ALZ‐801 inhibited the formation of Aβ 42 fibril from low‐molecular‐weight (LMW)‐Aβ 42 in the presence of Aβ 42 seeds. HS‐AFM also revealed that globular aggregates from LMW‐Aβ 42 were significantly larger with ALZ‐801, with few fibrils noted. MTT and LDH assays indicated that ALZ‐801 prevented LMW‐Aβ 42 ‐induced cytotoxicity but did not reduce cytotoxicity induced by high‐molecular‐weight‐Aβ 42 . ALZ‐801 can inhibit Aβ 42 aggregation by preventing both nucleus formation and fibril elongation, while promoting large globular oligomer formation, and can significantly reduce LMW‐Aβ 42 ‐induced cytotoxicity. These findings underscore the potential of ALZ‐801 as an effective DMT for APOE ε4 homozygous patients with AD.

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