A novel agent called exisulind has been shown to inhibit the rise in prostate-specific antigen (PSA) in men with recurrent prostate cancer, according to a recent article published in the Journal of Urology.
The prostate is a male sex gland located between the bladder and the rectum. Prostate cancer is a common occurrence among older men and, when caught early, is considered curable with radiation and surgery. However, many patients still experience a cancer recurrence following treatment. A few tests presently exist that help predict if a patient is at high-risk for cancer recurrence following surgery. These tests include blood prostate specific antigen (PSA) levels, or levels of a protein produced by the prostate; Gleason score, which is determining the aggressiveness of cancer; and abnormalities in DNA. The spread of cancer and visual examination of prostate specimens following surgery are two additional factors that are taken into consideration when predicting if a patient is at high-risk for cancer recurrence.
When prostate cancer recurs after surgery or radiation therapy it can be treated by hormonal therapy, chemotherapy, surgery or radiation therapy. All of these treatments have significant side effects and it is not clear that survival is improved even when responses are achieved. Therefore, researchers continue to investigate new treatments for men with prostate cancer who have relapsed after primary treatment.
Exisulind is the first member of a new class of compounds known as selective apoptotic antineoplastic drugs. Findings from previous studies indicate that exisulind selectively destroys cancerous and precancerous cells, leaving normal cells unscathed. Exisulind works by inhibiting an enzyme (protein) called cyclic GMP-phosphodiesterase (cGMP-PDE) that is overexpressed in cancerous and pre-cancerous cells. By inhibiting cGMP-PDE, normal enzymes involved in cellular death are activated.
Researchers from Columbia University recently conducted a trial involving 96 men with rising PSA levels following a radical prostatectomy. Patients received either exisulind or placebo (inactive substance) for one year. Overall, exisulind-treated patients had a significantly greater drop in PSA levels during the study period than patients in the placebo group. Compared with placebo, exisulind significantly suppressed the increase in PSA in all patients. In addition, the rate at which PSA levels in the blood increased was delayed in patients on exisulind by 5.5 months compared with those on placebo. Exisulind was well tolerated.
These data suggest that exisulind has the potential to extend the time from biochemical recurrence indicated by rising PSA levels to the need for androgen deprivation (hormone) therapy without producing typical hormone-related adverse events, such as impotence or hot flashes. These researchers suggest that exisulind could limit the cost and morbidity of therapy, increase patient quality of life and extend treatment options.
Although these results are encouraging, it is currently unknown if the suppression of PSA levels will translate into an improved survival rate due to the relatively short follow up time of this trial. Persons with prostate cancer may wish to speak with their physician about the risks and benefits of exisulind or about the participation in a clinical trial further evaluating this therapy. Two sources of information regarding ongoing clinical trials that can be discussed with a doctor include comprehensive, easy-to-use services provided by the National Cancer Institute (cancer.gov) and eCancerTrials.com. eCancerTrials.com also provides personalized clinical trial searches on behalf of patients. (Journal of Urology, Vol 166, No 3, pp 882-886, 2001)