PSA Kinetics Affect Prognosis in Patients With Castration-resistant Prostate Cancer Treated With Enzalutamide

There is little evidence regarding the predictive value of prostate-specific antigen (PSA) kinetics in patients with castration-resistant prostate cancer treated with an androgen receptor signaling inhibitor. This study investigated the correlation between PSA kinetics and prognosis in patients with castration-resistant prostate cancer treated with enzalutamide.

We analyzed data from 103 patients who received enzalutamide as primary treatment for castration-resistant prostate cancer at our hospital, focusing on the associations between overall survival and PSA kinetics variables, such as maximal PSA response, PSA nadir, and time to PSA nadir.

The median PSA level at the initiation of enzalutamide was 18.1 ng/ml (interquartile range=7.9-61.2 ng/ml). The median maximal PSA response rate was 88% (interquartile range 55-98), and the median PSA nadir was 1.84 (interquartile range (IQR)=0.38-14.7) ng/ml. The median time to PSA nadir was 19 (IQR=6-28.5) weeks. Maximal PSA response rate <90% [hazard ratio (HR)=2.28, 95% confidence interval (CI)=1.03-5.03, p=0.0413], PSA nadir >2 ng/ml (HR=2.30, 95%CI=1.05-5.07, p=0.0379), time to nadir <19 weeks (HR=2.48, 95%CI=1.15-5.35, p=0.0204) were all independently predictive of shortened overall survival even after adjusting for pre-treatment factors.

Maximal PSA response, PSA nadir, and time to PSA nadir correlated with survival in patients with castration-resistant prostate cancer receiving enzalutamide as a first-line therapy.