Comparing the effectiveness and safety of abiraterone acetate and enzalutamide for the treatment of metastatic castration-resistant prostate cancer.

This study compared the effectiveness and safety of abiraterone acetate (Zytiga; AA) and enzalutamide (Xtandi; ENZ) in patients with metastatic castration-resistant prostate cancer (mCRPC). The data showed that both medication improve outcomes compared to placebo and ENZ is more effective in improving survival without cancer progression and delaying PSA progression compared to AA for the treatment of patients with mCRPC.

Metastatic castration-resistant prostate cancer (mCRPC) is an aggressive form of prostate cancer that has spread beyond the prostate gland and is no longer responsive to hormonal therapy such as androgen-deprivation therapy (ADT). ADT reduces the production of androgens (male sex hormones such as testosterone). Reducing these androgens prevents cancer cell growth. Men with mCRPC usually have high levels of prostate-specific antigen (PSA). PSA is a protein made by the cells of the prostate gland. It is used as a marker of cancer progression when it rises after treatment.

Abiraterone acetate (AA) is a medication that blocks the effect of male sex hormones. Therefore, it slows down prostate cancer growth. Enzalutamide (ENZ) is an anti-androgen medication. It blocks testosterone from reaching PC cells. It is also used for the treatment of mCRPC. Both AA & ENZ have been shown to improve survival in patients with mCRPC. However, comparisons between AA and ENZ for the treatment of patients with mCRPC are still lacking.

This study analyzed 4 studies and involved a total of 5199 patients with CRPC. 2283 patients were treated with AA. 2916 patients were treated with ENZ.

Patients treated with AA were 31% more likely to have a better survival compared to patients treated with placebo. AA significantly reduced the risk of cancer progression by 36% compared to placebo. AA significantly reduced the risk of PSA progression by 48% compared to placebo.

Patients treated with ENZ were 33% more likely to have a better survival compared to patients treated with placebo. AA significantly reduced the risk of cancer progression by 65% compared to placebo. ENZ significantly reduced the risk of PSA progression by 81% compared to placebo.

Patients treated with ENZ were 45.3% more likely to survive without cancer progression compared to patients treated with AA. ENZ significantly reduced the risk of PSA progression by 63.5% compared to AA.

No differences in the overall survival and side effects were found between either AA or ENZ.

This study concluded that ENZ is more effective in improving survival without cancer progression and delaying PSA progression compared to AA for the treatment of patients with mCRPC.

This study looked back in time at medical records. The studies included had different patient populations and different methodologies. Further direct comparisons are needed.