Today, May 16, 2012, Dendreon, the makers of Provenge, disclosed a new analysis of data of its pivotal 512-patient study of men with castrate resistant prostate cancer who received sipuleucel-T (Provenge). The new analysis separated the men in the study into four quartiles based on their prostate-specific antigen (PSA) scores. The initial design of the study did not incorporate this analysis so its results might not be accurate.
This new look at the data showed that in men with castrate resistant prostate cancer, Provenge worked better (men had a longer survival advantage) if their PSA was lower, reflecting less advanced prostate cancer. This conclusion is in fact consistent with many “best guesses” of many of the knowledgeable scientists.
The analysis was led by Gerald Chodak, M.D. at Weiss Memorial Hospital in Chicago. It was posted online today on the American Society of Clinical Oncology’s in advance of its annual meeting in Chicago.
According to Mark Frohich, Chief Medical Officer at Dendreon, “All of these analyses support the robustness of clinical benefit for patients, and this PSA quartile data is helpful for patients when you think about sequencing of therapy…. “The data strongly argues that using it as early as possible is the best for the patient and still allows you to go on and get other therapies.”
In this new analysis of the Provenge study the researchers looked at survival times of men who entered the trial with PSA scores of less than or equal to 22.1; between 22.1 and 50.1; between 50.1 and 134; and over 134.
The chart below shows the survival time when matched with entering PSA scores. Provenge patients lived longer than placebo patients in all four quartiles, but the difference in median survival times was the largest among those with lower PSA scores.
PSA of 22.1 or less PSA of 22.1-50.1 PSA of 50.1-134 PSA of 134 and up
Provenge 41.3 months 27.1 months 20.4 months 18.4 months
Placebo 28.3 months 20.1 months 15 months 15.5 months
Difference 13 months 7.1 months 5.4 months 2.8 months
–Source, Gerald Chodak et al
The real issue is how valid is this data or is it just a fluke in the design of the trial? My gut and hope is that the data is real and this might provide a kick to the doctors to get teir patients started earlier on Provenge.
Joel T Nowak, M.A., M.S.W.
Does this mean that those of us with high grade PCa (GL.8-10 – which often shows a low PSA because of the low leak rate – have the best chance of benefitting from Provenge?
Bernard – Maybe, Because of the statistical issues I discussed we can not be sure.