GZMB and neoplasm: Given the role of granzyme B in the exertion of CTL function during immunotherapy, a granzyme B-targeting radiotracer, 68Ga-NOTA-GZP (25, 26), and its analog, 18F-AlF-mNOTA-GZP (42, 43), have recently been developed for noninvasive monitoring of tumor responses to ICIs in preclinical studies.