BACKGROUND: According to the American Cancer Society, prostate cancer is the most common type of cancer found in American men, other than skin cancer. There will be about 220,900 new cases of prostate cancer in the United States in the year 2003. About 28,900 men will die of this disease.
Prostate cancer is the second leading cause of cancer death in men, exceeded only by lung cancer. Although men of any age can get prostate cancer, it is found most often in men over 50. More than 70 percent of all prostate cancers are diagnosed in men over age 65. Prostate cancer is about twice as common among black men as it is among white American men. It is also most common in North America and northwestern Europe.
HOW PROSTATE CANCER PROGRESSES: Prostate cancer can be treated in a number of ways including surgery, radiation therapy, chemotherapy, cryosurgery, hormone therapy or watchful waiting. Prostate cancer has a high cure rate, but when it spreads, it is more difficult to treat and cure.
According to Michael Carducci, M.D., from Johns Hopkins University, more than 85 percent of men who have prostate cancer recurrences have them in their bone. He and colleagues wondered why men with prostate cancer die if it's only in their bones.
"It doesn't really go to organs. It's only in their bones. How does that kill anybody?" said Dr. Cadrucci.
Their theory is that men may be dying of prostate cancer from proteins circulating in the bloodstream. Endothelin is a protein that every person has, and it's responsible of the fine control of blood pressure. In men with prostate cancer, endothelin is overproduced.
TARGETING ENDOTHELIN: Endothelin targets a specific receptor on cells. The drug atrasentan is a compound that blocks the receptor that endothelin targets.
"We get to the lock before endothelin does. Therefore, the cancer cells never see this growth factor, the protein that really stimulates further growth. We get here and block it first," Dr. Carducci, said.
Endothelin is still circulating in these men, but it can't do any harm because it's been blocked. Early studies show the drug had a 52-percent delay in the time it took for men to have a new symptoms or disease progression. Studies also show it took double the time for the PSA levels, markers of prostate cancer, to rise again. In addition, In all men in the study, researchers found the atrasentan was actually hitting its target and protecting the bone.
"This may not necessarily kill cancer cells. It may slow prostate cancer down to a trickle. Although the cancer cells may still be alive, they're growing much slower or not at all for a period of time," Dr. Carducci said.
There are different studies ongoing using atrasentan for prostate cancer.
FOR MORE INFORMATION, PLEASE CONTACT:
Atrasentan Clinical Trials Information Line