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CHICAGO, June 3 (Reuters) - Adding Johnson & Johnson's Zytiga to standard hormone therapy reduced by nearly 40 percent the risk of death for men newly diagnosed with prostate cancer that had spread to other parts of the body, according to new trial results.
The study, presented at the annual meeting of the American Society of Clinical Oncology in Chicago, is most important for men outside of the United States, where it is more common for the disease to be diagnosed after it has metastasized.
Zytiga, or abiraterone acetate, is a pill that decreases production of testosterone, the hormone that stimulates growth of prostate tumors. The drug is approved for men whose cancer has worsened after treatment with docetaxel chemotherapy and for use before chemo for disease resistant to traditional hormone drugs.
At a U.S. list price of $9,400 a month, Zytiga is expensive. J&J's domestic Zytiga sales totaled just over $1 billion last year, and global sales were $2.26 billion.
The new data supports expanding the drug's use to earlier stages of prostate cancer. J&J is already seeking European Union approval in that setting, but is still considering whether to pursue U.S. approval.
"The difference here is ... patients who have not been on hormonal therapy," said Craig Tendler, head of global medical affairs at J&J's Janssen division. "This is much less common in the U.S. where we have very aggressive screening guidelines." Those guidelines, however, are changing and more men are declining to undergo testing.
The findings, following 2015 trials showing an advantage with chemotherapy, offer the first new options for metastatic prostate cancer patients in nearly 70 years, according to Dr Karim Fizazi, head of the department of cancer medicine at France's Gustave Roussy Cancer Center, who led the study.
In late 2011, the U.S. Preventive Services Task Force, a government-backed panel of independent physicians, recommended against routine prostate cancer testing, citing concerns that it often caught harmless tumors that did not need treatment and led to unnecessary procedures with side effects such as impotence and incontinence.
Tendler estimated that around 50,000 men a year in developed countries outside of the United States are initially diagnosed with metastatic prostate cancer.
At a median of 30 months after beginning treatment, men taking Zytiga and the steroid prednisone plus standard hormonal therapy had a 38 percent lower risk of death compared with men given hormone therapy and a placebo.
Zytiga was also associated with a 53 percent lower risk of the cancer worsening.
Severe side effects from the drug included high blood pressure in 20 percent of patients.
Fizazi said a trial to see if Zytiga has a benefit when added to hormonal therapy and chemotherapy is still under way.
A second study of nearly 2,000 men found that adding Zytiga to a standard initial regimen of hormone therapy for high-risk, advanced prostate cancer lowered the relative risk of death by 37 percent.
"We think these will be game-changers," said Dr Daniel Hayes, ASCO President from the University of Michigan Comprehensive Cancer Center, who was not involved in the study. (Editing by Matthew Lewis)