In this setting, a number of protein‐ or peptide‐based radiotracers have been fabricated to compensate the pitfalls of the antibody‐based probes.84, 85, 86, 87, 88, 89, 90, 91 For example, Trotte et al developed a 18F‐labeled affibody ligand that can effectively detect PD‐L1 expression in xenograft tumors by PET imaging, with preferable specificity, fast blood clearance, and low normal tissue uptake except nephridia.85 Larimer et al demonstrated that granzyme B PET imaging might serve as an effective biomarker for predicting responses to immunotherapy in human tumor xenograft models.89, 90. The gene discussed is CD274; the disease is neoplasm.