Hormonal Therapeutics Enzalutamide and Abiraterone Acetate in the Treatment of Metastatic Castration-Resistant Prostate Cancer (mCRPC) Post-docetaxel-an Indirect Comparison

Pui S Tan; Benjamin Haaland; Alberto J Montero; Christos E Kyriakopoulos; Gilberto Lopes

doi:10.4137/CMO.S13671

Hormonal Therapeutics Enzalutamide and Abiraterone Acetate in the Treatment of Metastatic Castration-Resistant Prostate Cancer (mCRPC) Post-docetaxel-an Indirect Comparison

Clin Med Insights Oncol. 2014 Mar 16:8:29-36. doi: 10.4137/CMO.S13671. eCollection 2014.

Authors

Pui S Tan¹, Benjamin Haaland², Alberto J Montero³, Christos E Kyriakopoulos³, Gilberto Lopes⁴

Affiliations

¹ Health Services and Systems Research, Duke-NUS Graduate Medical School, Singapore.
² Centre for Quantitative Medicine, Office of Clinical Sciences, Duke-NUS Graduate Medical School, Singapore. ; Department of Statistics and Applied Probability, National University of Singapore, Singapore.
³ Cleveland Clinic, Taussig Cancer Institute, Cleveland, OH, USA.
⁴ Hospital do Coração Cancer Center (HCor Onco), Brazil. ; Centro Paulista de Oncologia, Brazil. ; Oncoclinicas do Brasil, Brazil. ; Johns Hopkins University, Baltimore, MD, USA.

Abstract

Introduction: This study aims to make an indirect comparison between enzalutamide and abiraterone acetate for mCRPC post-docetaxel.

Methods: A search for published phase 3 trials was performed with PubMed. Indirect comparisons of enzalutamide (AFFIRM) to abiraterone acetate (COU-AA-301) on outcomes overall survival (OS), time to prostate-specific-antigen (PSA) progression, radiographic progression-free survival (PFS), and PSA response were constructed in the context of log-linear regression models.

Results: There was no statistically significant difference in OS (hazard ratio (HR) 0.85, 95% CI 0.68-1.07). However, there was some evidence that enzalutamide may outperform abiraterone acetate with respect to secondary outcomes: time to PSA progression (HR 0.40, 95% CI 0.30-0.53), radiographic PFS (HR 0.61, 95% CI 0.50-0.74), and PSA response rates (RRs) (OR 10.69, 95% CI 3.92-29.20).

Conclusion: While there was no statistically significant difference in OS, enzalutamide may be advantageous for secondary endpoints. Findings of this indirect comparison serve to be hypothesis-generating for future head-to-head trials.

Keywords: abiraterone acetate; enzalutamide; mCRPC; metastatic castration-resistant prostate cancer; post-docetaxel.