KLK2 and prostate cancer: Specifically, the prostate proteases KLK2 and KLK3 were exploited for activation of anticancer prodrugs developed for treatment of prostate cancer.11 Drugging KLKs for prostate cancer, for example, resulted in a boronic acid-based inhibitor of KLK3,12 while KLKs have been clinically tested by various approaches, and there have been success stories in this respect, PROSTVAC (an active immunotherapy vaccine that contains KLK3/PSA) being one such example.13 In contrast to the Lee et al.1 KLKs are druggable.11–14