For imaging of prostate cancer (PCa) lesions, a variety of small molecule-based prostate-specific membrane antigen (PSMA) ligands have been or are currently investigated in clinical trials (Cimadamore et al. 2018; https://clinicaltrials.gov/ct2/results?cond=Prostate+Cancer&term=PSMA&cntry=&state=&city=&dist= 2020). Here, FOLH1 is linked to cancer.