Lead Discovery via Scaffold Refinement: Structure-Guided Optimization of 1,2,4-Triazolo[1,5-a]Pyrimidines as Potent...

A unique series of 1,2,4-triazolo[1,5-a]pyrimidine derivatives was designed and synthesized as potential dual inhibitors of EGFR and CDK-2 to circumvent drug resistance in colorectal cancer patients through multi-targeted therapy. When tested against HCT-116 colorectal carcinoma cells, these compounds showed anticancer activity with lower toxicity against normal cells, thus providing a high selectivity index (> 2). Leads 12c, 12i, and 22 demonstrated potent kinase inhibition, with 22 yielding a CDK-2 IC₅₀ of 0.03 µM (seliciclib: 0.02 µM), and 12c delivering an EGFR IC₅₀ of 0.12 µM (erlotinib: 0.01 µM). These leads induced G₂/M cell cycle arrest and apoptosis in HCT-116 cells via upregulation of Bax, cytochrome c, and caspase-3, and downregulation of VEGF, AKT-1, and Bcl-2. Network pharmacology suggested EGFR and CDK-2 as key targets. Redocking reference ligands erlotinib (EGFR, PDB: 1M17) and seliciclib (CDK-2, PDB: 2A4L) confirmed docking poses, and binding interactions of 12c and 22 matched those of references. Using 100-ns molecular dynamics simulations proved the stability of ligand-protein complexes and further supported the reliability of predicted binding modes. Promising ADMET profiles and good drug likeness are evident in these leads. These data underscore the great potential of this scaffold for developing dual EGF/CDK-2 inhibitors aimed at resistance mechanisms in more aggressive cancers and can thus be pursued further in preclinical optimization.