Whether the combination of TRAIL plus Gamitrinib TPP (Gamitrinib^TPP, G-TPP) has activity against glioblastoma in vivo is studied. Luciferase-expressing U87 glioblastoma cells implanted in the right cerebral striatum of immunocompromised mice give rise to rapidly growing tumors by bioluminescence imaging, and treatment of these mice with vehicle, stereotactic delivery of TRAIL, or systemic administration of suboptimal concentrations of Gamitrinib TPP does not affect tumor growth in vivo. Similarly, systemic monotherapy with Gamitrinib TPP at concentrations (20 mg/kg as daily i.p. injections) that inhibit subcutaneous xenograft tumor growth in mice has no effect on orthotopic glioblastoma growth. In contrast, 2 cycles of intracranial TRAIL combined with systemic Gamitrinib TPP suppresses the growth of established glioblastomas, with no significant animal weight loss throughout treatment^[1].