CNR1 and glioblastoma: The use of δ 9-tetrahydrocannabinol (THC) in combination with Temozolomide (TMZ) has shown an effective anticancer activity through the activation of CB1 and CB2 to impair the proliferation of GBM [64] and a phase I clinical trial with a direct intratumoral injection of THC in recurring GBM has been safely conducted [66].