I previously said that if Dendreon missed the mark with its interim results for Provenge for late stage prostate cancer, I would not wait around for the final results. However, it appears that the interim results were quite positive, even though they did not make the predesignated FDA cutoff. Dendreon management explained why, with Provenge resulting in a 20% reduction of deaths, it is highly likely that when final results come in they will meet or exceed the 22% threshold needed for final approval. But this does mean more waiting for Dendreon as the final study won't be completed until mid-2009. Also, the company will continue to burn crucial cash during this final clinical stretch, leaving it weaker even if it gets final approval.
The Dendreon Provenge press release gave the basic information passed on from the independent data committee, so I'll focus on what management said in today's analyst conference.
In past Phase III trials Provenge showed more benefit over time than in the short run. This makes sense since its mode of action is to create an immune response to the prostate cancer. At this point in the prior studies the death risk reduction rate was 22%, and if that had been replicated in the current study, there was an agreement with the FDA that the trial could be stopped and approval quickly granted. However, the death reduction rate in the current study was 20%. That is not an unusual statistical fluctuation in a trial with this number of patients.
So on the whole, the interim results confirm the Dendreon story. In the past trials, when patients were looked at longer term, the death rate benefit (relative to placebo) increased to 33%.
But according to their agreement with the FDA, Dendreon does not need even that 33% reduction for approval. They only need a 22% reduction. That means that even if the trend of doing slightly worse than the earlier studies continues, the death risk reduction rate should come in around 29%, a very nice safetry margin above the 22% target.
Of course, a few adverse reactions (so far Provenge has proven extemely safe) or statistical fluctuations on the down side could still cause the study to fail. Also, I don't think the guarantee from the FDA is absolute. They will look at all the data and won't approve Provenge unless they feel it is safe and effective.
While it would have been nice to start getting this therapy out to prostate cancer victims quickly, it certainly now seems very hopeful that Dendreon will get the data needed to approve Provenge some time in 2008.
I own Dendreon stock and have owned it for years. You can read my Dendreon historical commentary and analyst conference summaries for more background.
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