Diazepam diminishes temozolomide efficacy in the treatment of U87 glioblastoma cell line

Aims Many patients with glioblastoma (GBM) suffer from comorbid neurological/psychiatric disorders and, therefore, are treated with psychopharmacological agents. Diazepam (DIA) is widely adopted to treat status epilepticus, alleviate anxiety, and inhibit chemotherapy‐associated delayed emesis in GBM patients. Even though temozolomide (TMZ) and DIA could be found as possible combination therapy in clinical practice, there are no reports of their combined effects in GBM. Hence, it may be of interest to investigate whether DIA enhances the antitumor efficacy of TMZ in GBM cells. Methods U87 human GBM was used to examine the effects of combined TMZ and DIA on cell viability, and the oxygen consumption within the cells, in order to evaluate mitochondrial bioenergetic response upon the treatment. Results The cooperative index showed the presence of antagonism between TMZ and DIA, which was confirmed on long‐term observation. Moreover, the level of apoptosis after the TMZ treatment was significantly decreased when administered with DIA (p