The agent Xtandi® (enzalutamide) improves survival and reduces the time to cancer progression compared to Casodex® (bicalutamide) among men with prostate cancer that has stopped responding to prior therapy with antiandrogens. These results were recently published as rapid communication in the Journal of Clinical Oncology.

Prostate cancer is the most frequently diagnosed cancer in men aside from skin cancer. An estimated 220,800 new cases of prostate cancer are diagnosed annually in the U.S., with more than 27,500 men dying from the disease.

Prostate cancer is stimulated to grow from exposure to the male hormone, testosterone. Therefore, an important treatment component for prostate cancer includes agents that block the formation of testosterone. This type of treatment is referred to as androgen deprivation therapy (ADT). There are several different types of ADT agents that prevent formation of testosterone through different mechanisms. Researchers continue to explore optimal therapeutic approaches for prostate cancer patients who stop responding to ADT.

Researchers recently conducted a clinical trial to directly compare two different agents that block the formation of testosterone. The trial, referred to as the STRIVE trial, included 396 men whose cancer had progressed despite prior ADT. Patients had both metastatic (cancer spread to distant sites in the body), as well as earlier-stage (nonmetastatic) prostate cancer.

One group of patients was treated with bicalutamide, and the other group was treated with enzalutamide, both of which are FDA approved for the treatment of prostate cancer. The results from both groups of patients were directly compared.

  • Patients treated with enzalutamide had a 76% reduced risk of cancer progression or death, compared to patients treated with bicalutamide.
  • The median time from initiation of therapy to progression of cancer among survivors (progression-free survival) was 19.4 months for those treated with enzalutamide, compared with 5.7 months for those treated with bicalutamide.
  • Enzalutamide was beneficial in patients with either metastatic or nonmetastatic cancer.

The researchers concluded that “Enzalutamide significantly reduced risk of prostate cancer progression or death compared with bicalutamide in patients with nonmetastatic or metastatic” cancer that had stopped responding to prior ADT.

Reference Penson D, Armstrong A, Concepcion R, et al. Enzalutamide Versus Bicalutamide in Castration-Resistant Prostate Cancer: The STRIVE Trial. Journal of Clinical Oncology. January 25, 2016, doi: 10.1200/JCO.2015.64.9285. Available at: Accessed February 5, 2016.

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