Provenge, despite its demonstrated survival advantage continues to be knocked as a viable treatment for men with castrate resistant prostate cancer. Why is this the case?
First, Provenge does not affect the PSA. Most men will continue to see their PSA rise, as well as their disease progress based on scans, while they take the treatment. Remember, the total treatment time is one month long.
Many of our other treatments do affect the PSA, so many men believe that Provenge is nothing more than a placebo. However, I have been saying that not all men are in fact candidates for Provenge as it takes time for its effects to begin!
Provenge should be considered as a very personalized treatment. Yes, it is personalized as it is made from your own blood, but many men with metastatic castrate resistant prostate cancer are not candidates and should not take the treatment.
Analysis of the data revealed that the single most important predictor of response to Provenge was a man’s Gleason score. The Gleason score is a measure of the aggressiveness of a man’s tumors or cancer.
In clinical trials men in men who had a Gleason score less than or equal to there was a significant difference in cancer progression. The placebo group had an average time to having their cancer progression was 9.0 weeks, while in the Provenge treatment group it was 16.0 weeks.
From a statistical standpoint this finding had a p-value of 0.002 (indicating a two in 1000 probability of this occurring by chance alone). In addition, in men receiving Provenge whose disease had not progressed six months after randomization had more than an eight-fold advantage in progression-free survival compared with those men who received placebo (34.7% versus 4%).
The take home is simple, only men with a Gleason 7 or less should be considered for Provenge. As I have always said Provenge MUST be taken immediately when a man becomes castrate. The earlier the disease progression and the less aggressive the disease the more effective the treatment will be for the individual. Men with later disease and more aggressive disease (greater than a Gleason 7) are not good candidates for the treatment and should consider Zytiga (with prednisone) or Xtandi instead.