Design and synthesis of novel Thiazolo[5,4-b]pyridine derivatives as potent and selective EGFR-TK inhibitors targeting resistance Mutations in non-small cell lung cancer

A novel series of substituted thiazolo[5,4-b]pyridine analogues were rationally designed and synthesized via a multi-step synthetic pathway, including Suzuki cross-coupling reaction. The Anticancer activity of all forty-five synthesized derivatives was evaluated against HCC827, H1975, and A549 Cancer cell lines utilizing the standard MTT assay. A significant number of the thiazolo[5,4-b]pyridine derivatives exhibited potent Anticancer activity. Notably, compounds 10b, 10c, 10h, 10i, and 10k emerged as the most promising Anticancer agents. The lead compound, N-(3-(6-(2-aminopyrimidin-5-yl)thiazolo[5,4-b]pyridin-2-yl)-2-methylphenyl)-2,5-difluorobenzenesulfonamide (10k), displayed remarkable potency with IC₅₀ values of 0.010 μM, 0.08 μM, and 0.82 μM against the HCC827, NCI-H1975 and A-549 Cancer cell lines, respectively, which were comparable to the clinically approved drug Osimertinib. Importantly, the potent derivatives 10b, 10c, 10h, 10i, and 10k exhibited selective cytotoxicity towards Cancer cells and showing no toxicity against the normal BEAS-2B cell line at concentrations exceeding 35 μM. Mechanistic studies revealed that the active compound 10k acts as an EGFR-TK autophosphorylation inhibitor in HCC827 cells. Furthermore, Apoptosis assays demonstrated that compound 10k induced substantial early Apoptosis (31.9 %) and late Apoptosis (8.8 %) in Cancer cells, in contrast to the control condition exhibiting only 2.0 % early and 1.6 % late Apoptosis. Molecular docking simulations of the synthesized compounds revealed that they formed essential hinge interactions and established hydrogen bonding with Cys797, indicating potential target engagement. These findings highlight the potential of the synthesized thiazolo [(Woodburn, 1999; Zigrossi et al., 2022) 5,45,4-b]pyridine derivatives as promising Anticancer agents, warranting further investigation for the development of novel targeted therapies against non-small cell lung Cancer.

Anticancer activity; Apoptosis; EGFR-TK; Lawesson's reagent; Molecular docking; Sulfonamide; Suzuki coupling; Thiazolo[5,4-b]pyridine.