NEW ORLEANS (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 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.