Men treated with Zytiga plus steroids who had not received chemotherapy gained at least 16 months before the cancer resumed spreading, twice the 8 month progression-free survival seen in those given steroids alone, according to research presented at the American Society of Clinical Oncology meeting in Chicago. The benefits were so strong that a safety monitoring board stopped the study in March and recommended all men take Zytiga.
“Taking Zytiga earlier can help patients maintain their quality of life free of pain, reduce the need for chemotherapy and live longer,” said lead researcher Charles Ryan, an oncologist at the University of California, San Francisco, in a telephone interview.
About 30,000 men in the U.S. die from advance prostate cancer each year, according to the American Cancer Society. Because patients generally live for about three years with the disease, there are roughly 100,000 men with prostate tumors looking for treatment, Ryan said. The malignancy is the second most common cause of cancer death in men.
Delaying Chemotherapy
Bruce Roth, a professor of medicine at Washington University in St. Louis, said he has at least 100 patients who are putting off chemotherapy who could benefit from Zytiga. He said many patients delay chemotherapy as long as possible, even as their disease progresses, because of the side effects, which can include fatigue and neutropenia, a condition that increases the risk of infections.“The pool of patients is very large,” Roth said. “There are patients who are waiting for something, but not willing to take on the toxicity of chemotherapy and decrease their quality of life.”
The findings could encourage doctors to start prescribing Zytiga even before it receives U.S. Food and Drug Administration clearance for use preceding chemotherapy, said Larry Biegelsen, an analyst at Wells Fargo Securities in New York, in a May 31 note to investors. His $525 million sales estimate for Zytiga in the U.S. this year may be too low, Biegelsen said. The drug is on track to generate $1.3 billion annually by 2015, he said.
Approval Plans
The company plans to request broader FDA approval in the second half of 2012, said Michael Meyers, Johnson & Johnson’s compound development team leader for Zytiga. It will also conduct another analysis of the study involving 1,088 men with spreading disease that hasn’t yet caused severe symptoms, after patients have been followed for a longer period, he said.The study was stopped after an interim review of the findings. Because more deaths occurred in patients given only the steroid prednisone, the researchers were able to determine their median overall survival was 27 months, the longest ever seen in a study of patients with advanced prostate cancer. Survival exceeded that seen in earlier trials of Dendreon’s Provenge.
Men treated with Zytiga had a 25 percent reduction in their risk of death during the time the study was under way, Meyers said. Because it was halted early, the median overall survival for those given Zytiga hasn’t been reached. Additional follow up is needed to conclusively determine how much longer Zytiga patients live and whether the difference is meaningful.
Finding the Benefit
About half of the men in the group given only steroids and whose disease worsened subsequently got chemotherapy, and 10 percent of them were given Zytiga, Ryan said. The additional treatments may have helped them live longer and could make it difficult to distinguish the pre-chemotherapy survival benefit from the Johnson & Johnson drug, he said.Most men with advanced prostate cancer say their goals are to keep pain at bay, function normally and delay the need for more toxic treatment, Ryan said. Zytiga helps with all three areas, he said.
“There is a highly significant delay in suffering from the disease,” he said. “We never reached a median time where all men had pain and needed opiates” to control it.
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