As early as 2013, we have known that a lower baseline prostate-specific antigen (PSA) is associated with a higher overall survival benefit from Provenge (sipuleucel-T) as found in the phase 3 IMPACT trial aka the Immunotherapy for Prostate Adenocarcinoma Treatment trial. It is shocking to us at Cancer ABCs how unknown this data is in both the patient community and in the medical community.
Recently, we have been working with a man who has a PSA that is under 1.0 whose oncologist has refused to give him Provenge because he claims that his PSA is too low to allow him to have an immune response!
This misconception is in direct conflict with the data produced by Shellhammer et al. which was published in Urology, 2013 (see reference below).
Shellhammer’s study was designed to explore the prognostic and predictive value of the PSA baseline on a man with castrate resistant prostate cancer if he received Provenge. The study evaluated 512 men and used data generated by the phase III IMPACT trial.
The baseline PSA values of the subject men were subdivided into quartiles to evaluate PSA treatment effect patterns. On analysis, it was found that PSA was the most influential baseline prognostic factor. Furthermore, treatment with Provenge appeared to have a more significant effect on overall survival with men who had the lowest baseline PSA levels.
In this study the estimated improvement in median survival varied from 13.0 months in the lowest baseline PSA quartile to 2.8 months in the highest PSA quartile, the men with the lowest baseline PSA did much better and survived longer.
The most significant magnitude of benefit was obtained by those men with the lower baseline PSA scores.
These findings tell us that men with less advanced disease as measured by lower PSA scores gain the best survival advantage from Provenge.
The oncologist mentioned earlier in this post is in direct conflict with the data; he is wrong. This man should be given Provenge now when he stands to gain the most benefit from the treatment.
Urology. 2013 Jun;81(6):1297-302. doi: 10.1016/j.urology.2013.01.061. Epub 2013 Apr 9.; Schellhammer PF1, Chodak G, Whitmore JB, Sims R, Frohlich MW, Kantoff PW.