Resumen de Enzalutamide in metastatic castration-resistant prostate cancer before chemotherapy

María Dolores Alvarado Fernández, Inmaculada Reyes Torres, S. Fénix Caballero

• Objective: To determine whether enzalutamide and abiraterone may be regarded as Equivalent Therapeutic Alternatives (ETA) in the treatment of metastatic castration resistant prostate cancer (mCRPC) in patients who have not received chemotherapy by performing an adjusted Indirect Treatment Comparison (ITC). Method: A Pubmed search was performed to select mCRPC studies without prior chemotherapy, with significant benefit in overall survival, and which met inclusion criteria. ITC was performed using the Bucher method and the results were analyzed according to the ETA Guide. The cost/effectiveness calculation was performed with overall survival difference obtained using the area-under-curve (AUC) method (4.39 months). Results: Only two clinical trials met the criteria for performing the ITC: pivotal trials phase III of each drug. Adjusted ITC between enzalutamide and abiraterone showed a HR 0.95 (95% CI: 0.72-1.24), p >0.05. The 95% CI exceeded prespecified limit of clinical relevance. At the time of the approval of enzalutamide, these patients were treated with abiraterone. Since a similar efficacy derived from the indirect comparison can be assumed, enzalutamide would have the same cost as abiraterone. Conclusions: Adjusted Indirect Comparison (with a possible bias against abiraterone, because it is compared to prednisone and not to placebo) provides a similar balance of benefit/risk and benefit/cost of abiraterone and enzalutamide. Enzalutamide and abiraterone can be considered ETA in the proposed indication