Recent studies have shown that an early prostate-specific antigen (PSA) response to androgen receptor (AR)-targeting agents in metastatic castration-resistant prostate cancer (mCRPC) is associated with a better prognosis. We analyzed early PSA response to enzalutamide and oncological outcomes to study their prognostic significance in the Japanese population.
Fifty-one patients with mCRPC (26 of pre-docetaxel and 25 of post-docetaxel status) were treated with enzalutamide. The PSA progression-free survival (PFS), radiographic PFS (rPFS) and overall survival (OS) were assessed. The association of rPFS and OS in patients with an early PSA response at 4 weeks after commencement of enzalutamide was studied.
Early PSA responses were significantly associated with a longer rPFS (median of 47.9 vs. 20.1 weeks, p<0.001, in patients exhibiting a 50% PSA response; median of 40.9 vs. 20.1 weeks, p=0.016, in patients exhibiting a 30% PSA response). OS was also significantly associated with an early PSA response (p=0.002 for patients exhibiting a 50% PSA response, p=0.003 for patients exhibiting a 30% PSA response). Multivariate analysis showed that the predictors of a 50% PSA response were an interval to mCRPC and a docetaxel treatment history, while the predictor of a 30% PSA response was a docetaxel treatment history. Furthermore, a 50% PSA response was independently prognostic of rPFS.
An early PSA response to enzalutamide was significantly associated with a longer rPFS and OS. This information will aid in the management of patients treated with enzalutamide.
Anticancer research. 2016 Nov [Epub]
Haruo Kato, Yosuke Furuya, Yoshiyuki Miyazawa, Takeshi Miyao, Takahiro Syuto, Masashi Nomura, Yoshitaka Sekine, Hidekazu Koike, Hiroshi Matsui, Yasuhiro Shibata, Kazuto Ito, Kazuhiro Suzuki
Department of Urology, Gunma University Graduate School of Medicine, Gunma, Japan., Department of Urology, Gunma University Graduate School of Medicine, Gunma, Japan .