Exploring Pyrazolo[3,4‐ <i>b</i> ]Pyridine and Spiro‐Oxindole Hybrids as Selective CDK2 or EGFR Inhibitors for Targeted Cancer Therapy: Design, Synthesis, and Molecular Modeling Insights

A new series of pyrazolo[3,4-b]pyridine and spiro-oxindole derivatives were rationally designed, synthesized, and biologically assessed as either CDK2 or EGFR inhibitors with potential anticancer activity. The CDK2 inhibitory evaluation of pyrazolo[3,4-b]pyridines 6a-g and 7a-f revealed that compounds 6e, 7b, and 7c exhibited potent inhibition (IC₅₀ = 0.88, 1.89, and 1.23 μM, respectively), compared to roscovitine (IC₅₀ = 0.84 μM). Among the spiro-oxindole derivatives 8a-d, compounds 8b and 8c demonstrated remarkable EGFR inhibition (IC₅₀ = 0.13 and 0.09 μM, respectively) and significant activity against mutant EGFR^T790M (IC₅₀ = 0.32 and 0.14 μM) relative to gefitinib (IC₅₀ = 0.03 and 0.18 μM, respectively). Furthermore, compounds 6e and 8c exhibited selective cytotoxicity versus MCF-7 and MDA-MB231 cancer cells, respectively, with negligible cytotoxic effects on normal Vero cells. Flow cytometric analysis confirmed that compounds 6e and 8c induced G1-phase cell cycle arrest and apoptosis in MCF-7 and MDA-MB-231, respectively, accompanied by a pronounced increase in the Bax/Bcl-2 ratio, with values of 12.15 and 16.93 fold, respectively. Molecular docking studies combined with molecular dynamics simulations further supported stable ligand-protein interactions within CDK2, EGFR, and mutant EGFR^T790M active sites, with favorable binding energies and conformational stability throughout 100 ns trajectories. Collectively, these findings identify compounds 6e and 8c as promising lead scaffolds for further development of CDK2 or EGFR inhibitors with potent and selective anticancer properties.