Enzalutamide (E) vs abiraterone acetate (AA) in the treatment of metastatic, castration-resistant prostate cancer. Indirect comparisons and network meta-analysis for clinical practice

Abstract

Background: To compare efficacy and safety of E and AA in the treatment of metastatic, castration-resistant prostate cancer. Method(s): Efficacy and safety of E and AA were compared using the data of the PREVAIL, AFFIRM, COU-AA-302 and COU-AA-301 trials. All the data extracted from the selected trials were reported ad Hazard Ratio (HR) or Odds Ratio (OR). Overall survival was the primary end point of our analysis, all the side effects, grade IIIIV side effects, serious side effects, side effects leading to treatment discontinuation or death the secondary ones. Overall survival was assessed both in the entire population and in the subgroups of patients chemotherapy-naive or docetaxel-resistant. Result(s): The outcome of 5191 patients were reviewed. 1671 patients had been treated with E, 1339 with AA and 2181 with placebo. No significant differences were observed in the eligibility of the patients in the selected trials, and the enrolled patients were considered homogeneous for the final analysis. In the indirect comparison of E vs AA no differences were observed for overall survival both in the entire population (HR=0.955, IC95%=0.796-1.144, p=0.616), and in chemotherapy-naive (HR=0.947, IC95%=0.723-1.24, p=0.692), or docetaxel-resistant patients (HR=0.961, IC95%=0.753-1.228, p=0.75). Likewise, no significant differences were observed for all side effects (OR=0.414, IC95%=0.054-3.196, p=0.463), all grade IIIIV side effects (OR=1.36, IC95%=0.253-7.318, p=0.72), all serious side effects (OR=0.742, IC95%=0.137-4.006, p=0.729), all side effects leading to treatment discontinuation (OR=0.743, IC95%=0.132-4.193, p=0.736) or death (OR=0.572, IC95%=0.089-3.657, p=0.556). Conclusion(s): Although E and AA differ for pharmaceutical structure and mechanism of action, they seem to be comparable both for indication (pre- or post-docetaxel treatment in patients with metastatic, castration-resistant prostate cancer), and for efficacy or safety (both in chemotherapy-naive and in docetaxel-resistant patients). It follows that compliance, patients characteristics and costs can play a role in the decision making process of clinical practice.