By Ransdell Pierson
(Reuters) - Bristol-Myers Squibb Co's immunotherapy drug Yervoy failed to significantly prolong survival among patients with advanced prostate cancer who had previously received chemotherapy, according to limited data from the first late-stage study of the drug for the condition.
Yervoy (ipilimumab) frees the immune system to attack and kill cancer cells by blocking the action of a protein called CTLA-4. The closely followed drug was approved in 2011 to treat melanoma, the most deadly form of skin cancer, and is well on its way to achieving annual blockbuster sales of $1 billion.
An abstract, or limited summary, of findings from the prostate cancer study was released on Thursday. The trial involved almost 800 patients that had failed to benefit from drugs that lower the amount of testosterone - the male hormone that fuels prostate cancer - and from treatment with a standard chemotherapy called docetaxel.
Half the patients in the trial received Yervoy after treatment with a dose of radiation, while others received a placebo after radiation.
Patients taking Yervoy lived, on average, 11.2 months, compared with 10 months for those in the placebo group, a difference that was deemed slightly below statistical significance.
Drug-related side effects, including gastrointestinal problems, were similar to those seen with Yervoy in melanoma trials.
Researchers are slated to present full results of the trial, nicknamed the "043" study, late this month at a medical meeting in Amsterdam.
The best responses to Yervoy in the prostate cancer study were in patients with less-advanced disease, including those whose cancer had not spread to the lung and liver, according to the abstract.
That could bode well for a second Phase III trial of Yervoy, expected to be completed by 2015, which has enrolled patients who are asymptomatic or have only mild symptoms of prostate cancer, and whose cancer has not spread to the lungs or liver. Although previously treated with anti-testosterone drugs, they have not taken chemotherapy.
One of the leading approved treatments for prostate cancer is Johnson & Johnson's Zytiga. In trials of patients that had not previously been treated with chemotherapy, those taking Zytiga, on average, lived five months longer than those who received a placebo.
The American Cancer Society last year estimated that more than 28,000 U.S. men would die from prostate cancer in 2012, making it the second leading cause of cancer death behind lung cancer.
Bristol-Myers is also testing Yervoy, which is given by infusion, in a variety of other cancers, including those of the lung, stomach and ovaries.
(Reporting by Ransdell Pierson; editing by Andrew Hay)