Phase 1 and 2 trials in recurrent GBM, which assessed the radiopharmaceutical [213Bi]Bi/[225Ac]Ac-DOTA-substance P, found that a subgroup of patients with GBM, displaying a tumor diameter of <5 cm in combination with a KPS of >70, benefitted the most from TAT [28,29,30]. Here, TAC1 is linked to neoplasm.