Clinical outcome (CO) and predictive factors (PRE) evaluation of a cohort of castration resistant prostate cancer (CRPC) patients (pts) treated with abiraterone acetate (AA) in a named patient program (NPP): Preliminary results from a retrospective study.

Abstract

e16078 Background: AA provided a survival advantage compared to placebo, in pts who had received docetaxel for CRPC. Before the regulatory authority approval, AA was made available in Italy through a NPP supervised by the local ethic committees. The present retrospective study is aimed to assess PRE and CO in an unselected CRPC population which received AA by NPP. Methods: We retrospectively reviewed the clinical records of all pts treated with AA by NPP in our Institutions. For each pt we have recorded the pre and post-AA clinical history, the treatment details and outcomes. We have assessed the ability of a series of selected 22 clinical factors to predict AA response through a logistic regression analysis. Continuous variables were categorized by quartiles and chosen for the initial model after a univariate chi-square analysis. Results: To date we have collected a consecutive series of 136 pts from 13 Italian hospitals. The median age was 72 yrs (range 52-87). The median baseline PSA was 154 ng/ml (range 0.33->100.000); 80% and 16.7% of the pts showed bone and measurable lesions respectively. The median duration of AA treatment was 15 wks (range 1-73); 59 treatments are ongoing. Grade 3-4 toxicities were anemia (5 pts), nausea (1 pt), fatigue (4 pts), bone pain (3 pts), and hypokaliemia (1 pt). A PSA reduction > 50% was observed in 37.5% of the pts. Having a performance status (PS) 0-1 [(exp(beta) 4.541; p= 0.018], a previous ormonotherapy lasting >40 months [(exp(beta) 3.299; p= 0.020], baseline hemoglobin >12 g/dl [(exp(beta) 2.595; p= 0.074], no visceral organ involvement [(exp(beta) 1.929; p= 0.097] resulted to be independently predictive of a PSA reduction > 50%. The median PFS and OS were 5 mos and 14 mos, respectively; the 1-year PFS and OS rates were 25.7% and 53%, respectively. Conclusions: Our preliminary results have confirmed the efficacy of AA in second line CRPC outside clinical trials. Pts with good PS, with good hemoglobin levels, with long-lasting hormosensitivity, and without visceral organ involvement have higher probability to achieve a biochemical response to AA.