Given the selectivity for IDH2 mutations that are only found in hematologic malignancies or peripheral tumors as well as a low degree of brain penetration, AG-221 and preclinical mIDH2-selective inhibitors such as IDH2-C100 (Figure 12A) are of less interest for the development of PET probes for glioma imaging. Here, IDH2 is linked to central nervous system cancer.