ASCO: Data on J&J, Medivation meds spell trouble for Provenge

After last year's debut of Dendreon's ($DNDN) immunotherapy Provenge and Johnson & Johnson's ($JNJ) pill Zytiga, prostate cancer treatment may be in for another big shake-up. At the American Society of Clinical Oncology meeting over the weekend, Zytiga, Provenge and an experimental treatment all made headlines. Unfortunately for Provenge, however, not all the headlines were positive.

Already approved for post-chemo use, Zytiga could now change the standard treatment approach for early disease. We knew the study was positive: In April, the trial was stopped to open Zytiga therapy up to all the participating patients. Now, we have numbers: Patients treated with Zytiga plus prednisone lived at least 16 months before their cancer progressed, compared with 8 months in the steroid-only arm.

The data hinted at an overall survival benefit, but because the study was stopped, there wasn't enough time to see whether the benefit was statistically significant. That fact has touched off a debate--should the trial have been stopped?--but analysts and experts say the study still stands to change the way early prostate cancer is treated. For instance, Wells Fargo's Larry Biegelsen now thinks his $525 million sales estimate for this year may be too low, Bloomberg reports.

Meanwhile, a continuing flow of positive news about Medivation's experimental therapy MDV3100 has people buzzing about--among other things--combining it with Zytiga for a one-two treatment punch. "These drugs have great potential given together. [They are] very different agents that I hope will be complementary," Johann Sebastian de Bono, lead investigator in an MDV3100 study, told Xconomy.

In post-chemo patients, MDV3100 delivered a median overall survival fo 18.4 months, compared with 13.6 months in placebo patients. "I think these are the best survival data we have seen in the postchemotherapy setting," de Bono said.

What does all this mean for Dendreon and Provenge? The new data "will drive docs to use the oral drugs quickly," Citigroup's Yaron Werber said in a note over the weekend. "This is a big issue for Provenge." Investors appear to agree: Dendreon stock was down more than 6% this morning.

- get the release from J&J's Janssen unit
- see The New York Times story
- read the Forbes article
- check out the Xconomy column