Resumen de Comparison of the effectiveness between abiraterone and enzalutamide in metastatic castration-resistant prostate cancer

Betel del Rosario García, F. Gutiérrez Nicolás, José Alberto Morales Barrios, Ruth Ramos Díaz, Julia Nazco Casariego, Ana Plata Bello, María Rosario García Marrero

• Objectives: Enzalutamide (ENZ) and abiraterone (AA) have been shown to improve the survival of patients diagnosed with metastatic castration-resistant prostate cancer (mCRPC). Currently, only a few studies have directly compared the efficacy of both drugs, so comparative analyses may contribute significantly to therapeutic positioning. The present work will aim to evaluate the effectiveness of AA versus ENZ as first-line treatments in mCRPC.

  Method: All patients diagnosed with mCRPC and undergoing either AA or ENZ as first-line therapy were included in this retrospective study. The progression of total serum prostate-specific antigen (PSA) levels at three (VPSA3) and six months (VPSA6) from the start of the treatment, and the time to biochemical progression (TTbP) were analyzed to assess treatment effectiveness. The rate of individuals achieving a decrease in PSA ≥50% after three months from the start of the treatment (PSA50) was also determined.

  Results: A total of 42 patients were included: 40.5% were treated with AA and 59.5% with ENZ. The VPSA3 was significantly higher in ENZ group (–43.5 versus +25.9 ng/mL; p = 0.04). No differences were observed between groups for VPSA6 (–10 versus +8.1 ng/mL; p = 0.23). The median TTbP was 28 months for the AA group and was not reached in ENZ group (p = 0.27). PSA50 was 74% for AA treated patients compared to 80% for the ENZ group (p = 0.026).

  Conclusions: The early decline in total PSA levels (three-month) was more pronounced in those patients with mCRPC treated with ENZ. However, these differences in biochemical response were equivalent after six-months of treatment and did not translate into a better TTbP. Although these results have not yet been correlated with effects on patient survival, this effect could position ENZ as the treatment of choice in situations where a rapid response is required