Synthesis of Imidazole-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-Linked 1,2,3-Triazole Hybrids as Potent EGFR-Targeting Anti-Lung Cancer Agents

Abstract Objective: This study describes the design, synthesis, and biological evaluation of novel imidazole-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-1,2,3-triazole hybrids acting as potent inhibitors of the epidermal growth factor receptor (EGFR) in lung cancer pathways. Methods: A series of 1,2,3-triazole derivatives (VIIa–VIIo) was synthesized via a one-pot 1,3-dipolar cycloaddition reaction of 6-(chloromethyl)-3-(1-methyl-1H-imidazol-2-yl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine 8,8-dioxide (V) with sodium azide and various aryl alkynes at 60°C. The in vitro antiproliferative activity of these newly developed hybrids was evaluated against human lung cancer cell lines using the standard MTT cell viability assay. Results and Discussion: The chemical structures of all synthesized compounds were unambiguously confirmed by ESI-MS, 1H, and 13C NMR spectroscopy. Hybrids VIIl and VIIm demonstrated pronounced cytotoxic profiles, exhibiting IC50 values ranging from 2.09 ± 0.25 to 5.09 ± 0.58 μM against the targeted cancer cells, which is comparable to the clinical reference drug erlotinib. Notably, in vitro kinase assays revealed that compound VIIm possesses exceptional EGFR inhibitory efficacy (IC50 = 0.36 ± 0.02 μM), fully surpassing the potency of erlotinib (IC50 = 0.42 ± 0.02 μM). Conclusions: A novel library of imidazole-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine-1,2,3-triazole conjugates was successfully validated as effective anticancer leads. The most active compounds exhibited significant selectivity, showing negligible toxicity toward the non-malignant HEK293 cell line. In silico molecular docking simulations confirmed that the highly active derivatives possess superior binding affinities, with energy scores spanning from –9.98 to –10.88 kcal/mol, compared to erlotinib (–7.69 kcal/mol). Consequently, minor structural optimizations of scaffolds VIIl and VIIm offer a highly promising strategic direction for developing next-generation therapeutic candidates in targeted lung cancer oncology.