The Phase 3 COU-AA-302 Study of Abiraterone Acetate Plus Prednisone in Men with Chemotherapy-naïve Metastatic Castration-resistant Prostate Cancer: Stratified Analysis Based on Pain, Prostate-specific Antigen, and Gleason Score.

In the COU-AA-302 study (NCT00887198), abiraterone acetate plus prednisone (AAP) significantly improved outcomes in patients with metastatic castration-resistant prostate cancer (mCRPC) versus prednisone alone.

Baseline clinical parameters predicting that treatment response could help inform clinical decisions were explored.

To identify patients who derive the greatest clinical benefit from AAP treatment.

A total of 1088 mCRPC patients treated with either AAP or prednisone in the first-line setting in COU-AA-302 were included in this post hoc analysis.

Abiraterone acetate1000mg daily versus placebo, both plus prednisone 10mg daily.

Univariate and multivariable Cox regression analyses were performed, including clinical and pathological parameters for the primary end points overall survival (OS) and radiographic progression-free survival (rPFS), and secondary study end points. Tumor-associated baseline parameters independently impacting OS were applied to stratify patients according to possible treatment effects.

Baseline prostate-specific antigen (PSA), tumor-related pain as assessed by the Brief Pain Inventory-Short Form (BPI-SF), and Gleason score (GS) at primary diagnosis were identified as tumor-associated variables that independently impacted OS. AAP significantly improved outcomes versus prednisone in both group 1 (BPI-SF 0-1 and PSA <80 ng/ml and GS <8; p=0.006; hazard ratio [HR]: 0.61) and group 2 (BPI-SF 2-3 and/or PSA ≥80 ng/ml and/or GS ≥8; p=0.03; HR: 0.84). The differences observed for treatment effects between groups 1 and 2 for OS (HR: 0.61 vs 0.84), rPFS (HR: 0.41 vs 0.59), and time to chemotherapy (HR: 0.64 vs 0.71) were not statistically significant.

AAP significantly improved outcomes in mCRPC patients compared with prednisone alone regardless of baseline pain and PSA level, and GS at primary diagnosis with no significant differences between observed treatment effects in groups 1 and 2.

Treatment with abiraterone acetate and prednisone (compared with treatment with prednisone only) for metastatic castration-resistant prostate cancer increased survival in all patients in the study regardless of pain, prostate-specific antigen levels at the start of treatment, and Gleason score at primary diagnosis.

European urology. 2017 Sep 19 [Epub ahead of print]

Kurt Miller, Joan Carles, Jürgen E Gschwend, Hendrik Van Poppel, Joris Diels, Sabine D Brookman-May

Department of Urology, Charité Berlin, Berlin, Germany. Electronic address: ., Valld'Hebron Institute of Oncology, Valld'Hebron University Hospital, Barcelona, Spain., Department of Urology, Technical University of Munich, Munich, Germany., Katholieke Universiteit Leuven, Leuven, Belgium., Janssen EMEA HEMAR, Beerse, Belgium., Department of Urology, Ludwig-Maximilians University (LMU) Munich, Munich, Germany; Janssen Research & Development, Los Angeles, California, USA.