Many of us are aware of the newly approved drug Zytiga (abiraterone). It had demonstrated a survival advantage for men who are castrate resistant and failed chemotherapy. Zytiga was approved by the FDA in April and many of us with advanced prostate cancer have been taking advantage of the drug. You can learn more about Zytiga by searching for it in this blog.

MDV3100 another new investigational drug with a similar methods of action has already begun its phase 3 trials. Since the studies of MDV3100 have targeted men who are similar to those who are taking Zytiga, the press has bantered about the possibility that MDV3100 will be too late on the market when and if it is ultimately approved by the FDA.

However, Medivation Inc, which expects key data this year from a pivotal trial believes that could have a competitive advantages over Zytiga. Earlier this year they readjusted their Phase 3 trial of MDV3100 with the goal of triggering an interim analysis during 2011. Their hope is that the survival data will be strong enough to allow them to obtain early FDA approval.

“We want to do whatever we can to make our drug available to as many patients as possible,” Medivation Chief Executive Officer David Hung told Reuters in a telephone interview. “It is always good to minimize the lead of a competitor.”

The Zytiga trial of 1,195 patients — designed to show at least a 20 percent reduction in the risk of death — ended up demonstrating a 35 percent benefit.

The 1,199-patient Medivation study is “very, very similarly powered,” Hung said. He declined to comment on whether the trial has reached the number of deaths (520) needed to trigger the interim analysis.

Zytiga is designed to work inside cancer cells to block testosterone production, while MDV3100 aims to interfere with the ability of testosterone to bind to prostate cells, just like casodex. “Instead of trying to deplete the key, we just jam the lock,” Hung said.

Hung said that MDV3100, if approved, would have several advantages over Zytiga. The fact that the Zytiga can cause hypertension and liver damage and so has to be taken in combination with the steroid prednisone, while MDV31000 is not taken with a steroid. He also said that MDV3100 involves taking one pill daily as opposed to twice daily as required by Zytiga. Hung also said that Zytiga needs to be taken on an empty stomach since food can increase the amount of the drug absorbed by the body, but that is not an issue with MDV3100.

The other really exciting issue is that there would be nothing to stop a man from taking Provenge while on MDV3100. One of the biggest issues with Provenge is that both PSA and disease progression are not effected by the treatments, but by coupling Provenge with MDZ3100 it might be possible to take advantage of both treatments at the same time. Steroids can not be taken while taking Provenge.

Finally, the Medivation CEO said there is evidence from animal studies and early human trials that MDV3100 could have a mechanistic advantage in blocking testosterone receptors, particularly in men with earlier-stage cancer. Perhaps, MDV3100 might better be used to target earlier stage disease.

Like Zytiga, studies show that MDV3100 between 10 and 20 percent of hormone-resistant prostate cancer patients do not respond to the drugs, which Hung said is probably due to the fact that advanced cancer is being driven by a number of pathways independent of testosterone.

Joel T Nowak, M.A., M.S.W.