By Jimmy Downs

Thursday Oct 18, 2012 (foodconsumer.org) -- A new trial in the New England Journal of Medicine suggests that enzalutamide, formerly known as MDV3100, can significantly extend the survival time for patients with castration resistant prostate cancer after chemotherapy.

Howard I. Scher, M.D. at Memorial Sloan-Kettering Cancer Center in New York, New York and colleagues conducted the trial and found patients with castration-resistant prostate cancer after chemotherapy who used enzalutamide had a median survival of 18.4 months, compared to 13.6 months for those who were on the placebo.

Enzalutamide targets multiple sites in the androgen-receptor signaling pathway. Androgen is a promoter for prostate cancer and disrupting the androgen-receptor signaling pathway means androgen could not promote cancer growth or the drug slows the cancer growth.

A total of 1199 men with castration resistant prostate cancer, which is highly dangerous, after chemotherapy, were subject to the phase 3, double-blind placebo-controlled trial. Eight hundred patients were randomly assigned 160 mg per day of enzalutamide and 399 patients were assigned a placebo.  Th primary outcome was the overall survival.

An interim analysis of 520 prostate cancer deaths showed that the median overall survival for those who used enzalutamide was 18.4 months, compared to 13.6 months for those who used the placebo.

Enzalutamide also provided  superior secondary outcomes or end points.  Among prostate cancer patients, 54% of enzalutamide users reduced the prostate specific antigen or PSA compared to 2% in those who were using the placebo. 

Additionally, the soft-tissue response rate, the quality of life response rate, the time to PSA progression, radiographic progression-free survival, the time to the first skeletal related event in enzalutamide users and non-users were 29% versus 4%, 43% versus18%, 8.3 versus 3.0 months, 8.3 versus 2.9 months, 16.7 versus 13.3 months, respectively. 

Like many other cancer drugs, enzalutamide was associated with higher rates of fatigue, diarrhea, and hot flashes.  And 0.6% or five patients receiving enzalutamide suffered seizures.

The researchers concluded "Enzalutamide significantly prolonged the survival of men with metastatic castration-resistant prostate cancer after chemotherapy."

Castrate-resistant prostate cancer is by definition a disease whose progression can't be stopped by androgen depletion therapy and it may be featured with either a continuous rise in serum prostate-specific antigen (PSA) levels, the progression of pre-existing disease, and/or the appearance of new metastases.

Prostate cancer, which is expected to be diagnosed in more than 230,000 men each year in the United States, is in many cases preventable.  The disease in many cases is not aggressive as other types of cancer.   But the disease still kills about 40,000 men each year in the United States.