A Polypharmacology-Driven Approach to Alzheimer's Disease and Tauopathies: Rational Design, Synthesis and Characterization of Amino-Pyrazole-Based Multikinase (GSK-3β/FYN-α/DYRK1A) Inhibitors.

Accumulation of microtubule-associated protein tau is a neurotoxic hallmark in Alzheimer's disease (AD) and related tauopathies. To date, no small molecule disease-modifying therapy exists, underscoring an urgent unmet need. In this context, the multitarget-directed ligand (MTDL) approach offers a viable polypharmacological option for modulating key pathways/targets involved in tau pathology. Leveraging the interconnected roles of GSK-3β, FYN, and DYRK1A in tau hyperphosphorylation, we conducted a computational and X-ray crystallography-driven SAR exploration around our previously disclosed GSK-3β/FYN/DYRK1A inhibitor ARN25068 (1). Modification of the thieno[3,2-d]pyrimidine central core of 1 led to the discovery of quite well-balanced GSK-3β/FYN/DYRK1A triple-targeting analogs (27, 28 (ARN25699) and 31 (ARN26646)). Among these, 28 displayed a favorable ADME profile, acceptable pharmacokinetic properties, and efficacy in an in vitro tau phosphorylation assay, outperforming three single-target inhibitors tested individually or in combination. These compounds represent promising MTDL leads poised to advance therapeutic innovation in AD and related tauopathies.