Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2017

Predictive Value of Early Prostate Specific Antigen (PSA) Response in Patients with Metastatic Castrate-Resistant Prostate Cancer (mCRPC) Treated with Post-Docetaxel Abiraterone (#184)

Courtney Morley 1 , Rachel Delahunty 1 , Phillip Parente 1 2 , Carmel Pezaro 1 2 , Andrew Mant 1
  1. Eastern Health, Box Hill, VICTORIA, Australia
  2. Eastern Health Clinical School, Monash University, Melbourne, VIC, Australia


Abiraterone acetate plus prednisolone (abiraterone) is approved for patients with mCRPC who have failed docetaxel. Some studies suggest an early PSA-response (≥50% reduction from baseline PSA) by week 4 is associated with improved survival, although data are conflicting.1, 2  

This study aimed to investigate the relationship between timing of PSA-response and survival outcomes in mCRPC patients treated with post-docetaxel abiraterone.


We conducted a retrospective audit of mCRPC patients treated at Eastern Health with post-docetaxel abiraterone between September 2011 and September 2016. Data regarding baseline demographics, disease characteristics, treatment, haematological and biochemical parameters and survival outcomes were recorded. PSA-response by weeks 4, 8 and 16 was calculated.


Fifty-five patients treated with post-docetaxel abiraterone were screened to identify 36 patients with available early PSA values.  The median age was 70 years. Patients had received a median of 8 cycles of docetaxel. By weeks 4, 8 and 16 a PSA-response had been achieved by 31%, 36% and 39% of patients respectively.

The median duration of abiraterone treatment for patients who achieved a PSA-response by week 4 was 8.0 months, and by week 16, was 7.5 months; for those who did not achieve a PSA-response by week 16, it was 5 months.

The median overall survival (OS) of patients who achieved a PSA-response by week 4 compared to those who did not was 11.9 versus 11.7 months (HR 0.80, 95%CI 0.34-1.87; p=0.34); for those who achieved a PSA-response by week 16 compared to those who did not, median OS was 11.9 versus 11.7 months (HR 0.80, 95%CI 0.36-1.99; p=0.38).


This study suggests an early PSA-response to post-docetaxel abiraterone may not predict significantly improved survival. However, non-routine PSA measurement introduced strong selection bias in this cohort. Prospective assessment of early efficacy signals should be encouraged.

  1. Nakayama M et al, Association of Early PSA Decline and Time to PSA progression in Abiraterone Acetate-Treated Metastatic Castration Resistant Prostate Cancer; A Post-hoc Analysis of Japanese Phase 2 Trials. BMC Urol 2016; 16(1):27.
  2. Rescigno P et al, Prostate-specific Antigen Decline After 4 weeks of Treatment with Abiraterone Acetate and Overall Survival in Patients with Metastatic Castration-resistant Prostate Cancer. European Urology. 2016 (70) 724-31.