An experimental formulation of leuprolide, administered by injection every six months, safely and effectively reduced serum testosterone levels in men with prostate cancer. These results were published in the Journal of Urology.

Testosterone is a male hormone produced mainly by the testicles. Many organs in the body are composed of cells that respond to or are regulated by exposure to testosterone. Cells in the prostate have testosterone receptors and when exposed to testosterone, are stimulated to grow. When cells that have testosterone receptors become cancerous, the growth of these cancer cells can be increased by exposure to testosterone. The objective of hormonal therapy for prostate cancer is to prevent the cancer cells from being exposed to testosterone.

Medications known as leutinizing hormone-releasing hormone (LHRH) analogues suppress testosterone levels by turning off the signal for testosterone production by the testicles. Leuprolide is a type of LHRH analogue, and commonly-used formulations are administered every month or every three months.

To evaluate the safety and effectiveness of a new formulation of leuprolide that is administered by injection every six months, researchers conducted a study among 111 men with prostate cancer. The leuprolide formation that they evaluated is known as LA-2585 (45.0 mg). Men were studied for a period of twelve months and received two injections of LA-2585 (45.0 mg). The primary study outcome was successful suppression of serum testosterone levels.

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  • By day 28, 99% of the men achieved testosterone suppression (testosterone levels below 50 ng/dl).
  • Average time to achieve testosterone suppression was 21 days.
  • At study completion, 99% of men had testosterone levels below 50 ng/dl, and 88% had testosterone levels below 20 ng/dl.
  • Average serum level of prostate-specific antigen (PSA) decreased by 97%, from 39.8 ng/ml at baseline to 1.2 ng/ml at 12 months.
  • Hot flashes were the most commonly reported adverse effects of treatment.

The researchers conclude that LA-2585 (45.0 mg) “consistently produced and maintained safe and effective testosterone suppression.”

Men with prostate cancer may wish to talk with their doctor about the risks and benefits of participating in a clinical trial further evaluating this or other novel therapeutic approaches. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (www.cancer.gov) and www.cancerconsultants.com.

Reference: Crawford ED, Sartor O, Chu F et al. A 12-Month Clinical Study of LA-2585 (45.0 MG): A New 6-Month Subcutaneous Delivery System for Leuprolide Acetate for the Treatment of Prostate Cancer. Journal of Urology. 2006;175:533-536.

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