Abiraterone Produces Promising Results in Men with Hormone Refractory Prostate Cancer

Posted on March 2nd, 2010 by

According to the results of Phase II clinical trials, the investigational drug abiraterone appears to be active in men with hormone refractory prostate cancer (HRPC). These results were published in the Journal of Clinical Oncology.

Current treatment options for prostate cancer include watchful waiting, surgery, chemotherapy, radiation, or hormonal therapy. Hormonal therapy is designed to block testosterone from stimulating the growth of hormone-dependent types of prostate cancer. Some hormonal therapies (such as surgical removal of the testes or use of medications such as leuteinizing hormone releasing hormone [LHRH] analogues) inhibit production of testosterone by the testes. Other therapies, such as the antiandrogen drugs, block the activity of testosterone.

Some prostate cancers become resistant to standard hormonal therapy and require a different treatment approach; this condition is known as hormone refractory prostate cancer. Because hormone refractory prostate cancer can be difficult to treat, new agents and treatment approaches continue to be evaluated.

Abiraterone is an experimental drug that is taken orally. It blocks the production of androgens (male hormones such as testosterone) not only by the testes but also by the adrenal glands.

To evaluate the safety and effectiveness of abiraterone in the treatment of men with hormone refractory prostate cancer, researchers have conducted Phase II clinical trials.

One of the studies enrolled 47 men with hormone refractory prostate cancer that had previously been treated with Taxotere® (docetaxel)-based chemotherapy.[1] All were treated with abiraterone.

  • PSA declines of 30% or more were observed in 68% of patients.
  • PSA declines of 50% or more were observed in 51% of patients.
  • PSA declines of 90% or more were observed in 15% of patients.
  • The median time to PSA progression was 169 days.
  • 41% of 27 patients with circulating tumor cells had a significant decline following treatment with abiraterone.

The other study enrolled 58 men with progressive, metastatic, hormone refractory prostate cancer that had previously been treated with Taxotere.[2] Study participants were treated with abiraterone plus prednisone.

  • 36% of patients experienced a greater than 50% decline in PSA levels.
  • A partial reduction in detectable cancer occurred in 18% of patients.
  • Median time to disease progression was 169 days.
  • Treatment reduced circulating tumor cells.

The results of these studies suggest that abiraterone is active against advanced, hormone-refractory prostate cancer. Phase III clinical trials of abiraterone are underway.

References:


[1] Reid AH, Attard G, Danila DC, et al. Significant and sustained antitumor activity in post-docetaxel, castration-resistant prostate cancer with the CYP17 inhibitor abiraterone acetate. Journal of Clinical Oncology [early online publication]. February 16, 2010.

[2] Danila DC, Morris MJ, de Bone JS. Phase II multicenter study of abiraterone acetate plus prednisone therapy in patients with docetaxel-treated castration-resistant prostate cancer. Journal of Clinical Oncology [early online publication]. February 16, 2010.

Tags: News, Prostate Cancer, Refactory/Recurrent Prostate Cancer

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