After recently writing about Dendreon's Provenge and other prostate cancer drugs, the long awaited survival data has finally been revealed in a late breaking abstract at the American Urological Association.
Unfortunately, when I tried to access the abstract online, the sign-up form said it would take several days for someone to get back to me. Huh? Obviously they have a ways to go in communicating data compared to their efficient brethen at ASH and ASCO, who allow guests, patients and interested parties to sign in and freely read the abstracts from the meetings.
The snapshot of the data is therefore summarised here courtesy of Forbes, Dendreon's press release and the WSJ app on my iPhone (the website will frustratingly only give you the first paragraph or so).
Essentially, Provenge prolonged the lives of men with advanced prostate cancer who had failed hormone therapy and were not responding to treatment with hormonal therapy. Taxotere was previously approved after failure of hormone therapy with improved survival by 3 months over placebo and a response rate of approx. 18%. Provenge extended life by 4.1 months in previously pre-treated patients (25.8 vs. 21.7 months), a statistically significant result (P<0.032).
However, the trial design makes it difficult to compare whether Provenge exerted any effect over Taxotere alone. Therapy was started with either
with placebo or Provenge. As soon as tumours grew, men on placebo
got a frozen version of Provenge, followed by Taxotere. Those who started on Provenge also got Taxotere
when they stopped responding to initial treatment. There was no Taxotere only arm to determine the incremental effect of Provenge, as might be expected. Therein lies the rub for ODAC and the FDA.
In 2007, the FDA declined to approve the vaccine, preferring to wait for survival confirmation from the 512 patient IMPACT study presented today. Those discussions led to a target of a reduction in risk of death by 22%. The IMPACT data just squeaked in at 22.5%. There is no guarentee that approval for Provenge will be a dead cert given the marginal improvement, unconventional trial design and likely exhorbitant price.
The main advantage of Dendreon's Provenge over chemotherapy is better tolerability, since the most common side effect was flu-like symptoms but not heightened stroke or cerebrovascular events, whereas Taxotere can cause severe myelosuppression, fatigue and occasionally, febrile neutropenia.
The next six months will be interesting as a) Dendreon can expect to file with the FDA later this year and b) ODAC can give biotech companies with fuzzy trial designs a run for their money; remember GPC/Spectrum and satraplatin? I'd sure love to be a fly on the wall for the Dendreon ODAC meeting…
Disclosure: To avoid confusion, I should add that while I don't normally tend to post immediate news about drugs or pharma on this blog, my particular interest stems from having lost a dear father to the disease 9 years ago. It is my hope that one day others will have a better opportunity for an improved quality of life after being diagnosed with advanced cancer. Most advances are inevitably incremental, rather than being a lengthy improvement in quality of life and survival, as Gleevec was for CML patients. As for Dendreon's Provenge, I'm not sure that flu-like symptoms and a high price tag will be the panacea that many patients and their families were hoping for 🙁