Biological basis and clinical study of glycogen synthase kinase-3β-targeted therapy by drug repositioning for glioblastoma

Background: Glycogen synthase kinase (GSK)-3 beta has emerged as an appealing therapeutic target for glioblastoma (GBM). Here, we investigated the therapeutic effect of the current approved drugs against GBM via inhibition of GSK3 beta activity both, in experimental setting and in a clinical study for recurrent GBM patients by repositioning existent drugs in combination with temozolomide (TMZ). Materials and Methods: Progression-free and overall survival rates were compared between patients with low or high expression of active GSK3 beta in the primary tumor. GBM cells and a mouse model were examined for the effects of GSK3 beta-inhibitory drugs, cimetidine, lithium, olanzapine, and valproate. The safety and efficacy of the cocktail of these drugs (CLOVA cocktail) in combination with TMZ were tested in the mouse model and in a clinical study for recurrent GBM patients. Results: Activation of GSK3 beta in the tumor inversely correlated with patient survival as an independent prognostic factor. CLOVA cocktail significantly inhibited cell invasion and proliferation. The patients treated with CLOVA cocktail in combination with TMZ showed increased survival compared to the control group treated with TMZ alone. Conclusions: Repositioning of the GSK3 beta-inhibitory drugs improved the prognosis of refractory GBM patients with active GSK3 beta in tumors. Combination of CLOVA cocktail and TMZ is a promising approach for recurrent GBM.