Discovery of a CI-994 derivative as a dual modulator of class I HDACs and Wnt/β-catenin signaling for Alzheimer's disease therapy

Alzheimers disease (AD) is a multifactorial disease with mixed pathologies. Consequentially, drugs targeting multiple pathological processes may offer synergistic benefits. While histone deacetylase (HDAC) inhibitors have demonstrated efficacy in alleviating AD-related pathologies in animal models, the neuroprotective Wnt/{beta}-catenin signaling pathway remains compromised in AD brain. CI-994 is a class I HDAC inhibitor containing N-(2-aminophenyl)-benzamide. Our recent studies indicate that CI-994 is also an activator of Wnt/{beta}-catenin signaling by stabilizing Wnt co-receptor LRP6. We herein use CI-994 as a scaffold to develop novel potent dual modulators of class I HDACs and Wnt/{beta}-catenin signaling for AD therapy. Our lead compound, W2A-28, selectively inhibits class I HDAC1, 2 and 3 with IC50 values of 0.51 M, 0.68 M, and 0.22 M, respectively, and shows no inhibitory activities on other HDACs. Furthermore, W2A-28 potently activates Wnt reporter activity with an EC50 value of 1.61 M in Wnt-3A-expressing HEK293 cells. As expected, activation of Wnt/{beta}-catenin signaling by W2A-28 is associated with elevated LRP6 protein level. Importantly, W2A-28 displays excellent microsomal stability in both mouse and human liver microsomal stability assays, alongside high permeability and a lack of active efflux in MDR1-MDCKII models. Critically, W2A-28 treatment significantly enhances histone acetylation, activates Wnt/{beta}-catenin signaling, and suppresses tau phosphorylation in AD patient-specific cerebral organoids carrying APOE {varepsilon}4/{varepsilon}4 or APOE {varepsilon}3/{varepsilon}4 with PSEN1 M146V mutation. Our findings position W2A-28 as a promising multi-target drug candidate for AD therapy.