Abarelix
timothy roome
7:59 p.m. ET (2359 GMT) May 23, 2000
NEW ORLEANS, May 23 (Reuters) - A prostate cancer drug that works more
quickly than existing drugs may provide patients and doctors a little peace
of mind, researchers said on Tuesday.
They said a drug developed jointly by Amgen and Praecis Pharmaceuticals
stops a characteristic "spike'' in testosterone levels caused by other
prostate cancer treatments.
Dr. John Trachtenberg of the the Princess Margaret Hospital in Toronto said
he hoped the drug, called abarelix, might also be a more effective treatment
for prostate cancer, although he stressed it was too early to tell.
Prostate cancer is the biggest cancer killer of men in the Western world
after lung cancer. More than 180,000 cases of prostate cancer will be
diagnosed in U.S. men this year and nearly 32,000 men will die of it.
About 85 percent of patients have hormone-dependent prostate cancer. They
can be treated by cutting off testosterone, either by removing the
testicles, where the hormone is produced, or by using a drug to block
production.
But, Trachtenberg said, using drugs to block testosterone often first causes
levels of the hormone to surge. "Clearly, the aim is to suppress from day
one,'' he said in an interview.
He told a meeting of the American Society of Clinical Oncology (ASCO) that
abarelix can do that.
He did a phase III trial - an advanced trial - of 235 men with
hormone-dependent prostate cancer. Half got abarelix and half got TAP
Pharmaceuticals' Lupron, a standard treatment. Both groups also got
bicalutamide, another prostate cancer drug.
Trachtenberg said 80 percent of the men who got abarelix had the desired
testosterone level - the equivalent of castration - after eight days while
none of the men on Lupron did.
After three months both groups of men had the desired testosterone levels.
"I think it's an elegant drug because it does what we want,'' he said.
He said more studies will see whether abarelix helps men live longer and
disease-free.
Most anti-testosterone prostate drugs work to increase levels of a hormone
known as luteinizing hormone releasing hormone (LHRH) antagonists. Abarelix
actually works against LHRH, as well as against follicle stimulating hormone
(FSH), and is known as a gonadotrophin releasing hormone antagonist.
Trachtenberg said some evidence suggests that in men, FSH can stimulate
cancer cells and eventually make them resistant to hormone therapy. He said
abarelix suppresses FSH, too, and he said that might make these cancers more
controllable over the long run.