The promising performance of [99mTc]Tc-maSSS-PEG2-RM26 in PC-3 cells and animal model, led to its clinical testing in prostate and breast cancer patients (Chernov et al. 2023), where it demonstrated no adverse effects and the ability to visualize GRPR-expressing lesions, even previously unknown bone metastasis in a patient. The gene discussed is GRPR; the disease is breast carcinoma.