(UroToday.com) There has been a rapid evolution in treatment options for patients with non-metastatic castration-resistant prostate cancer since the spring of 2018. Up until the presentation of SPARTAN and PROSPER trials, reporting on the use of apalutamide and enzalutamide in non-metastatic castration-resistant prostate cancer, at GU ASCO in February 2018, there were no specifically approved treatment options for these patients. These agents, as well as darolutamide (on the basis of data from ARAMIS), were subsequently approved on the basis of demonstrated improvements in metastasis-free survival. In a plenary abstract presentation in the Oral Abstract Session: Prostate Cancer session at the 2021 ASCO GU Cancers Symposium, Dr. Felix Feng provided an exploratory analysis investigating potential biological signatures of patients with long-term responses.