Pyrazole derivatives as dual COX-2/EGFR inhibitors with anticancer potential: Optimization of difenamizole Analogs

COX-2 and EGFR are overexpressed in glioblastoma multiforme (GBM) representing attractive therapeutic targets. Based on the non-selective COX inhibitor "Difenamizole", which is characterized by its BBB-penetrating ability, we designed novel analogues with larger N-substituents to enhance COX-2 selectivity and introduce EGFR inhibition. Derivatives 6c, 7c, 8c, 8d, 9d, and 10a showed potent analgesic effects with AUC values: 31.69-39.23, comparable to Celecoxib (AUC = 31.57) and better than Difenamizole (AUC = 27.05). Compounds 8d and 10a demonstrated potent COX-2 inhibitory activity, comparable to Celecoxib (IC₅₀ = 0.06, 0.05, and 0.05 μM, respectively) with high selectivity for COX-2 over COX-1 (SI = 148.83, 199.4, and 298.6, respectively). Additionally, compound 10a showed potent inhibitory activity against EGFR (IC₅₀ = 0.098 μM), approaching that of Erlotinib (IC₅₀ = 0.06 μM). In glioblastoma cytotoxicity assays, compound 10a displayed significant cytotoxicity against U-251 cells (IC₅₀ = 8.8 μM), comparable to Staurosporine (IC₅₀ = 7.5 μM) and exceeding NS-398 (IC₅₀ = 23.14 μM), as well as marked superior potency against SNB-75 cells (IC₅₀ = 2.6 μM), exceeding both Staurosporine and NS-398 (IC₅₀ = 12.9 and 16.2 μM). Taken together, compound 10a represents a promising dual-targeted candidate for controlling GBM, with particular efficacy against the SNB-75 cell line, and reveals a distinctive profile compared with previously reported pyrazole derivatives by combining high COX-2 selectivity, EGFR inhibition, and GBM cytotoxicity.