A pharmaceutical composition and method for treating brain cancer are provided. The method includes administering to a patient in need thereof an effective amount of one or more compounds that include moclobemide, clorgyline, clorgylines Near-infra-red dye Monoamine Oxidase Inhibitor (NMI), and MHI 148-clorgyline, and their salt thereof. The composition and method are particularly effective in reducing the size of glioblastomas that are temozolomide (TMZ) resistant.