KLK3 and prostate cancer: Changes in prostate cancer disease burden as identified by PSMA-targeting radiotracers correlate with PSA response, but few studies have shown correlation between PSA changes and qualitative PET-based disease response (Hope et al. 2017; Schmidkonz et al. 2018; Zacho and Petersen 2018; Afshar-Oromieh et al. 2018; Aggarwal et al. 2018; Ettala et al. 2020; Emmett et al. 2019; Shagera et al. 2022).