Structural basis for a p21-activated kinase 4 and nicotinamide phosphoribosyltransferase dual inhibitor.

Simultaneous inhibition of oncogenic signaling and metabolic pathways represents a promising approach for cancer therapy. KPT-9274, a clinical stage compound, has been reported as a dual inhibitor of p21-activated kinase 4 (PAK4) and nicotinamide phosphoribosyltransferase (NAMPT), but its structural basis has remained undefined. Here, we present high-resolution crystal structures of PAK4 and NAMPT in complex with KPT-7523, an analog of KPT-9274, determined at 2.20 and 1.45 Å resolution, respectively. In PAK4, the 2-aminopyridine moiety of KPT-7523 enables dual binding, occupying the adenine-binding site for ATP and simultaneously engaging the substrate-binding cleft in the C-lobe, thereby interfering with both catalytic and regulatory functions. In NAMPT, the same scaffold inserts into the NAD+ active site in an extended conformation that preserves critical interactions. Biophysical assays revealed distinct affinities across the two targets. These findings highlight the 2-aminopyridine moiety as a versatile pharmacophore that is adaptable to structurally unrelated proteins and provide a framework for designing next-generation dual inhibitors in cancer therapy.