Enthalpy-Informed Design of Dasatinib-Derived Small-Molecule Inhibitors of Transthyretin Amyloidogenesis

Transthyretin (TTR) amyloidosis is driven by dissociation of the native tetramer into aggregation-prone monomers, making kinetic stabilization of the tetramer an established therapeutic strategy. Here, we demonstrate that binding enthalpy-guided optimization provides an effective strategy for developing selective TTR stabilizers. Starting from a kinase inhibitor-derived scaffold, stepwise optimization comprising scaffold simplification, terminal phenyl modification, and halogen substitution yielded compound 29, which exhibits aggregation inhibitory activity comparable to tafamidis and close to that of acoramidis. Isothermal titration calorimetry revealed that optimization predominantly improved binding enthalpy, while changes in binding free energy were modest. Combined X-ray and neutron crystallographic analyses suggested that the favorable enthalpy originates from enhanced shape complementarity and weak interactions rather than conventional hydrogen bonds. Importantly, compound 29 maintains robust binding to TTR in human plasma. These findings demonstrate that binding enthalpy can serve as a practical parameter for optimizing TTR amyloid inhibitors.