Survival extended by Dendreon cancer vaccine: study

By Bill Berkrot

NEW YORK (Reuters) - An experimental cancer vaccine developed by Dendreon Corp (DNDN.O) improved three-year survival of patients with advanced prostate cancer by 38 percent compared with a placebo in what could be a breakthrough for tens of thousands of men who suffer from the disease.

The tiny biotech company has been on a roller-coaster ride that has seen its shares go from $2.55 in March to $25 earlier on Tuesday before a 45 percent plunge just before the news.

Patients in the 512-subject study who received Dendreon's Provenge lived an average 4.1 months longer than those who received a placebo with no major adverse side effects in the late-stage clinical trial, researchers said.

Patients lived 25.8 months after receiving the vaccine compared with 21.7 months for those taking placebos, according to data from the closely watched study unveiled on Tuesday.

"This is a game changer in my business," said Dr. David Penson, associate professor of urology at the University of Southern California, who presented the data at the American Urological Association meeting in Chicago.

"I have no doubt that if this drug becomes commercially available in the United States, it will replace chemotherapy" in this patient population, Penson said in a telephone interview.

The results further raise the likelihood that Provenge will become the first approved therapeutic vaccine for any type of cancer. Dendreon plans to seek U.S. approval of Provenge, known chemically as sipuleucel-T, in the fourth quarter.

Prostate cancer is the most common cancer in American men aside from skin cancers, according to the American Cancer Society. More than one million men have the disease in the United States and one in six men will be diagnosed with prostate cancer during their lifetime.