Study Points to New Prostate Drug

For men with advanced prostate cancer, the news for decades has been mostly bleak. Until recently, only two treatments had been shown to prolong survival.

Abiraterone has emerged as a potential third new treatment for prostate cancer following approval earlier this year of Jevtana, a chemotherapy agent, and Provenge, a cancer vaccine.

Researchers reported Monday that the drug abiraterone, being developed by Johnson & Johnson, extended survival by an average of 3.9 months among men with cancer that has spread beyond the prostate and for whom other treatments have failed. Among men, prostate cancer is the second-leading cancer killer, behind only lung cancer.

Johnson & Johnson plans to file for new-drug approval in the U.S. and Europe by year-end, raising prospects that the drug could be on the market next year. The drug, a pill, works by blocking production of hormones that fuel prostate tumors.

The abiraterone study, presented at the European Society for Medical Oncology meeting in Milan, follows approval earlier this year of two other therapies—Jevtana, a chemotherapy agent from Sanofi-Aventis SA, and Provenge, a cancer vaccine developed by Dendreon Inc., which marshals the immune system to fight the disease.

"When you have drugs that act in different ways and each is giving some measurable benefit, that is significant progress in a field where new agents have come along very rarely in the past," says Steve K. Clinton, director of prostate and genitourinary oncology at Ohio State University's James Cancer Hospital and Research Institute, Columbus. Dr. Clinton wasn't involved in the current study and doesn't have consulting relationships with the companies.

Still, the overall improvement is modest for each therapy. Jevtana increased survival by an average of 2.4 months compared with standard chemotherapy. Provenge added an average of 4.1 months of life. Researchers say the results are impressive, nevertheless, because the studies involved patients whose tumors progressed after treatment with several different therapies.

"These drugs are first tested in dying patients with no other therapy options and with months to live," says Johann de Bono, a researcher at the Institute of Cancer Research and Royal Marsden Hospital in London. The hope, as with treatments for many cancers, is that they will lead to much longer survival when studied in patients with early-stage disease.

The abiraterone study involved 1,195 patients from 13 countries whose disease was considered "castration resistant," meaning it had progressed despite surgery or drugs to shut down production of the androgen hormone testosterone. The patients had also failed chemotherapy.

The 797 patients randomly assigned to abiraterone plus the steroid prednisone lived on average 14.8 months compared with 10.9 months for those treated with the steroid plus a placebo. The trial was stopped early after an interim data check determined the drug's benefit, enabling those on placebo to convert to the treatment.

Abiraterone patients were more likely than those on placebo to experience side effects such as an increase in blood pressure and retention of fluids. But they didn't lose their hair or have an increased risk of infection—problems associated with conventional chemotherapy.

Androgen hormones, particularly testosterone, fuel prostate tumors. Conventional hormone therapy blocks androgens produced by the testes. Abiraterone appears to target androgens also produced elsewhere, even by the tumors themselves, said Dr. de Bono, who presented the study in Milan. "These tumors are their own androgen factories."

Assuming abiraterone wins regulatory approval, oncologists will have to work out how it fits with the other new remedies. "What we really need, that we don't have at the moment, is the wisdom to know which one to use at what time and in what order," Dr. Clinton says.

Cost could be a factor. The three-treatment Provenge regimen has been controversial partly because of the $93,000 cost. Dendreon has said treatment costs are comparable with chemotherapy if total costs of care are taken into account.

Chadi Nabhan, division director of hemotology/oncology at Advocate Lutheran General Hospital, Park Ridge, Ill., and an investigator on Provenge studies, says he doesn't see the treatments as rivals. It is possible that by giving one treatment after the other, doctors will be able to extend life beyond what's possible with one strategy alone, he said.

Copyright The Wall Street Journal 2010