Changes in prostate-specific antigen kinetics during androgen-deprivation therapy as a predictor of response to abiraterone in chemonaïve patients with metastatic castration-resistant prostate cancer

Purpose: Metastatic castration-resistant prostate cancer (mCRPC) has a poor prognosis. Abiraterone acetate (AA), enzalutamide, and chemotherapy are first-line treatments for patients with mCRPC. This study examined prognostic factors for AA response in the form of prostate-specific antigen (PSA) kinetics throughout androgen-deprivation therapy (ADT) in chemonaïve patients with mCRPC. Materials and Methods: We retrospectively included data from 34 chemonaïve patients with mCRPC who had received AA at some point between January 2017 and December 2018. We separated patients into two study arms according to the decrease in PSA percentages after use of AA for 3 months. We correlated PSA kinetics parameters with response and compared the two study groups with respect to PSA kinetics. Results: The patients’ median age was 77 years. In the total group of patients, 64% had a response to AA, whereas 35% did not. The ratio of the PSA level at nadir to the level during ADT was significantly higher in the AA-sensitive group (19.78 vs. 1.03, p=0.019). Conclusions: Patients who experienced a dramatic change in PSA level during ADT were more likely to be resistant to AA after progression to mCRPC. Chemotherapy rather than AA might be more suitable as a first-line treatment for these patients.