Probing structural requirements for thiazole-based mimetics of sunitinib as potent VEGFR-2 inhibitors

Novel thiazole analogs 3a, 3b, 4, 5, 6a-g, 8a, 8b, 9a-c, 10a-d and 11 were designed and synthesized as molecular mimetics of sunitinib. In vitro antitumor activity of the obtained compounds was investigated against HepG2, HCT-116, MCF-7, HeP-2 and HeLa cancer cell lines. The obtained data showed that compounds 3b and 10c are the most potent members toward HepG2, HCT-116, MCF-7 and HeLa cells. Moreover, compounds 3a, 3b, 6g, 8a and 10c were assessed for their in vitro VEGFR-2 inhibitory activity. Results proved that compound 10c exhibited outstanding VEGFR-2 inhibition (IC₅₀ = 0.104 μM) compared to sunitinib. Compound 10c paused the G0-G1 phase of the cell cycle in HCT-116 and MCF-7 cells and the S phase in HeLa cells. Additionally, compound 10c elevated caspase-3/9 levels in HCT-116 and HeLa cells, leading to cancer cell death via apoptosis. Furthermore, compound 10c showed a significant reduction in tumor volume in Swiss albino female mice as an in vivo breast cancer model. Docking results confirmed the tight binding interactions of compound 10c with the VEGFR-2 binding site, with its binding energy surpassing that of sunitinib. In silico PK studies predicted compound 10c to have good oral bioavailability and a good drug score with low human toxicity risks.