GSTP1 and glioblastoma: In addition to ezatiostat, a study was conducted in 2020 on nipecotic acid ester, m-nitrophenyl-3-piperideinecarboxylate hydrochloride (MNPC) inhibitor, a dual inhibitor NAD(P)H quinone oxidoreductase 1, and GSTP1 for the treatment of GBM.