A drug that is already approved for prostate cancer has been shown to slow the spread of advanced forms of the disease for the first time, according to research released Saturday.
Zytiga, made by Johnson and Johnson, is being tested in a randomized phase III trial involving 1,088 men with prostate cancer at 151 cancer facilities in North America, Europe and Australia.
On average, participants in the study were diagnosed five years prior to entering the research but none had begun chemotherapy.
Their cancer had metastasized and had become resistant to initial hormone therapy, but they were not showing major symptoms.
According to interim results, the drug, abiraterone acetate, given in combination with prednisone, delayed the onset of pain and helped improve quality of life in patients whose cancer had metastasized.
In the Zytiga group, patients' cancer did not worsen for 16 months, compared to 8.3 months in the group that did not get the drug, Ryan said.
More analysis is needed to determine survival time. The full data set is expected in 2014.
"This drug extended lives and gave patients more time when they weren't experiencing significant pain from the disease," said Charles Ryan, an associate professor of clinical medicine at the University of California San Francisco Helen Diller Family Comprehensive Cancer Center.
"It appears that this medication may lay a foundation for the use of this drug at an earlier stage of prostate cancer, and its benefits may be able to be delivered to a much wider population of patients as a result."
The research was to be released at the 48th annual meeting of the American Society of Clinical Oncology in Chicago.
"These results are the culmination of years of research, and will truly transform the way we take care of patients with advanced prostate cancer," said Eric Small, chief of hematology and oncology at the UCSF Helen Diller Family Comprehensive Cancer Center.
"This is a wonderful milestone in our progress in treating prostate cancer, and provides advanced prostate cancer patients everywhere with an important new weapon to fight their cancer," he said.
US regulators last year approved abiraterone acetate for men whose disease had spread and who also were resistant to standard hormonal therapy, known as castration-resistant prostate cancer.
The drug was first conceived in a British lab in the 1990s, and works by blocking the production of hormones produced by the cancer that can help it grow.
The drug however carries risk for patients with a history of heart disease, high blood pressure, low blood potassium and fluid retention.
Prostate cancer is the second most common form of cancer in men. Some 241,000 new cases are diagnosed in the US each year and 28,000 men die of the disease annually, according to the American Cancer Society.
About one third of patients require no treatment because their disease does not spread.
