Abiraterone acetate plus prednisone: an evaluation of the long-term effectiveness in prostate cancer treated with hormonal therapy.

This study investigated if abiraterone acetate (Zytiga) and prednisone (Deltasone) added to androgen deprivation therapy (ADT) improve survival in patients with advanced prostate cancer. They found that this combination was effective at improving survival in these patients.

Metastatic prostate cancer (mPC) is cancer. that has spread from the prostate to other organs/ Androgen deprivation therapy (ADT) is the standard treatment for mPC. Androgens are male hormones. In PC they can stimulate cells to grow. ADT slows disease progression in mPC. ADT is not an effective long-term treatment. Patients become desensitized to the effects of ADT. Combining ADT with other medications may slow disease progression.

Abiraterone acetate (AbAc) and prednisone (PDN) are two drugs used to treat mPC. AbAc/PDN can also reduce the production of androgens. Combining AbAc/PDN with ADT lowers androgen levels using different mechanisms. This may reduce the chance of a patient becoming resistant to ADT. The long-term effectiveness of AbAc/PDN combined with ADT in patients with mPC is still unknown.

This study included 1199 patients with mPC. In the first phase, some patients were randomly assigned to a combination of AbAc/PDN and ADT. Another group of patients was assigned to ADT alone. After the first phase patients in the ADT group were allowed to switch to combination treatment. Treatment continued until disease progression or unacceptable side effects. The average follow-up time was 51.8 months. 

Combination treatment significantly improved overall survival compared to ADT alone (53.3 months vs 36.5 months). Combination treatment also improved other outcomes. These included pain progression and bone-related events.

Most side effects were known effects of ADT. Side effects were reported by 95% of the combination group and 93% of ADT alone patients. The rate of serious side effects leading to death was 6% for the combination and 4% for ADT alone patients. Hypokalemia (low potassium levels) was the most common serious side effects. It was observed in 4 combination-treated patients. 

The authors concluded that AbAc/PDN with ADT improved survival in patients with mPC.