Abiraterone Improves Castration-Resistant PCa Survival

The survival benefit was accompanied by a delay in the onset of symptoms and the need to use opiates for prostate cancer-related pain.
The survival benefit was accompanied by a delay in the onset of symptoms and the need to use opiates for prostate cancer-related pain.

Abiraterone acetate treatment prolonged survival by a median of 4.4 months in chemotherapy-naïve patients with metastatic castration-resistant prostate cancer, according to a new study.

The study results, published online in The Lancet Oncology, “strengthens the rationale for use of abiraterone acetate early” in the course of the disease, stated lead researcher Charles J. Ryan, MD, associate professor of medicine and urology at the University of California San Francisco, and colleagues.

For the study, researchers randomly assigned 1,088 asymptomatic or mildly symptomatic chemotherapy-naïve patients to receive oral abiraterone acetate (1,000 mg daily) with prednisone (5 mg twice daily) or placebo with the same dose of prednisone. After a median follow-up of 49.2 months, 65% of patients in the abiraterone group and 71% in the placebo group died.

The median survival time was 34.7 months in the abiraterone arm compared with 30.3 months in the placebo group, a survival difference that was “both clinically and statistically significant,” according to the investigators. Impressively, the finding held although 44% of the placebo group crossed over or subsequently received abiraterone.

The survival benefit was accompanied by a delay in the onset of symptoms and the need to use opiates for PCa-related pain. The median time to opiate use in the abiraterone group was 33.4 versus 23.4 months.

For subsequent treatment, 67% of patients in the abiraterone group and 80% in the placebo group received 1 or more approved drugs.

Adverse events of special interest that were more common in the abiraterone group included cardiac disorders, increased alanine aminotransferase, and hypertension. Some of these effects may have been related to mineralocorticoid excess.

The findings came from the final analysis of the phase 3 COU-AA-302 trial and confirmed interim results favoring abiraterone.

The confirmation also “reaffirms the importance of secondary androgen biosynthesis inhibition (via CYP17 with abiraterone),” commented Ravi Madan, MD, and William L. Dahut, MD, in an accompanying editorial. In the past 5 years, several trials of different therapies (anti-androgens, chemotherapy, immunotherapy, and radiopharmaceuticals) have demonstrated a survival benefit, according to the editorialists. The ideal sequence of therapies for managing this disease is a subject of much interest and investigation.

Sources

  1. Ryan, CJ, et al. The Lancet Oncology, Feb 2015; doi: http://dx.doi.org/10.1016/S1470-2045(14)71205-7.
  2. Madan, R, and Dahut, WL. The Lancet Oncology, Feb 2015; doi: http://dx.doi.org/10.1016/S1470-2045(15)70005-7.
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