Columbia Presbyterian Researchers Show Prostate Cancer Drug Significantly Arrests Tumor Growth With Minimal Side Effects

"These results suggest that Exisulind may delay disease progression in men with recurrent prostate cancer," says Dr. Erik Goluboff, Assistant Professor of Urology at Columbia University College of Physicians & Surgeons, Director of Urology at The Allen Pavilion of NewYork-Presbyterian Hospital, and the principal investigator of the trial. "This will subsequently prolong the time period between post-surgical PSA rise and the need for androgen deprivation therapies."

Exisulind is from a new class of compounds called selective apoptotic anti-neoplastic drugs (SAANDs). SAANDs inhibit cyclic GMP phosphodiesterase and selectively induce apoptosis (programmed cell death) in abnormally growing pre-cancerous and cancerous cells. Because SAANDs do not induce apoptosis in normal cells, they do not produce most of the adverse reactions or serious side effects normally associated with chemotherapeutic agents used to treat cancer.

Other available therapies, such as drugs, hormones, or radiation, try to limit spread of the disease and increase survival time by shrinking or stabilizing tumors but can impair patient recovery with severe side effects. "For instance, hormonal therapy produces high response rates in metastatic prostate cancer, but patients develop resistance over time," says Dr. Goluboff. "The side effects of hormonal treatment can significantly impact the patient's quality of life. New treatment options that might delay the need for such side effect-prone therapies could provide great benefit in the management of prostate cancer."

Previous studies in mice showed that Exisulind inhibits the growth of prostate cancer by 80 percent to 90 percent. In a related study of patients, researchers found that the drug also causes regression in the growth of precancerous colonic polyps, a condition that often leads to colon cancer.

For 12 months, the trial followed 96 prostate cancer patients who already had their prostate glands removed. All had rising prostate-specific antigen (PSA) levels indicating recurrent disease. Half received Exisulind, and half were given a placebo. The researchers measured the drug's ability to slow or halt disease progression by following patients' PSA levels. High levels of PSA are associated with more aggressive disease.

Imaging tests were performed before and after the study. All of the men were classified into risk groups with no statistical difference in age, race, and weight. The study showed a significant decrease in the rate of rise in PSA in patients given Exisulind compared with placebo.

Almost 185,000 new cases of prostate cancer will be diagnosed in the United States this year. More than 39,000 men will die of the disease, making it the second leading cause of cancer death in men. Although prognosis is good when prostate cancer is detected early, advanced disease, while treatable, has no cure.

Dr. Goluboff cautions that more research needs to be conducted to determine long-term effects in these patients and in other groups of patients with prostate cancer.

The study was funded by Cell Pathways Inc., developer of the drug Exisulind. The company first announced the results of the trial in November 1999.