Chromogranin A predicts outcome in prostate cancer patients treated with abiraterone.

In this retrospective study, we evaluated the chromogranin A (CgA) baseline value as a predictor of clinical outcome in patients with metastatic castration-resistant prostate cancer (CRPC) treated with abiraterone 1000 mg per day, whose disease progressed after docetaxel chemotherapy. In the 48 evaluable patients, serum CgA level was normal when !120 ng/ml (group A, nZ16), within three times the upper normal value (UNV) when between 120 and 360 (group B, nZ16), more than three times the UNV when R360 ng/ml (group C, nZ16). Decline in PSA level R50% or more (PSA RR) was observed in 26 of 48 (54%) patients. PSA response rate did not correlate with the CgA groups. CgA levels more than three times the UNV predicted an early radiological progressive disease in eight of 11 cases (73%). The median progression-free survival (PFS) among the CgA groups A, B, and C was 9.2, 9.2, and 4.8 months respectively, PZ0.0459. The median overall survival (OS) among the CgA groups was 19.0, 18.8, and 10.8 months respectively, PZ0.2092. In the multivariate analysis, PSA RR (nonresponsive vs responsive) and CgA levels (group 3 vs groups 1C2) were predictors of PFS (PZ0.0002 and PZ0.0047 respectively), whereas PSA RR only was significantly associated with OS (PZ0.0024), while CgA levels remained of borderline significance (PZ0.0919). A serum CGA level more than three times the UNV predicted PFS and showed a trend vs OS prediction, independently from PSA response, in CRPC patients treated with abiraterone.