In recent years, new treatments have led to improved survival in mCRPC. In Australia, access to novel hormonal agents abiraterone acetate (AA) and enzalutamide (ENZ) in the pre-chemotherapy setting are restricted to patients who are "unsuitable for docetaxel treatment on the basis of predicted intolerance". Generally, this represents older patients with poorer performance status. Understanding these access issues, we aimed to describe the demographics and PSA response rate (50% decline; PSA50) of mCRPC patients receiving pre-chemotherapy AA or ENZ treatment in Australia.
Information was extracted from ePAD, a multi-site prospective registry collecting demographic, clinicopathological, treatment and outcomes data from mCRPC patients treated in Australia. Demographic and PSA50 data from patients receiving pre-chemotherapy AA and ENZ were compared to results from COU-AA-3021 and PREVAIL2 respectively.
In this first analysis of ePAD data, 92 patients had received first line treatment. Comparing our ePAD AA cohort (n=15), to that of COU-AA-3021, median age was higher (75.5y v. 71y) and proportion of ECOG 0-1 was lower (85.7% v. 100%). PSA50 was also lower in the ePAD cohort (47% v. 62%). A similar pattern was seen comparing our ePAD ENZ cohort (n=45) to that of PREVAIL2 - median age was higher (81y v. 72y) and proportion of ECOG 0-1 was lower (81.8% v. 100%). PSA50 was also numerically lower (44% v. 78%).
The differences between clinical trial data and our initial examination of RWD through ePAD are likely driven by Australia's reimbursement criteria for AA and ENZ in the pre-chemotherapy setting. Our RWD suggests that clinical trial data cannot be directly extrapolated into the real world as the population treated under PBS subsidy is different. These results must be interpreted within the limitations of a small cohort size. We aim to present updated data with the growth of the database.