Using the mirror image of body’s main sugar glucose (so-called L-glucose), we plan to hijack the sugar addiction of glioblastoma (GBM) as a therapeutic target. To assessthe behavior of the unnatural form of glucose in living brain tumors, we have created a radioactively tagged L-glucose that wasfound to selective enter tumor, and not healthy, cells. These earlier findingsin rat tumors will be expanded upon using GBM tissue extracted from patients whose tumors were removed. We aim, for the first time, to 1) define the effectiveness of L-glucose in killing GBM cells within small human tissue samples called organoids and 2) use radioactive Lglucose with a rat model that has human GBM tumorsto image GBM progression. This work is expected to yield pivotal support for L-glucose as a therapy and diagnostic (theranostic) for GBM.