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The administration of the autologous immunotherapy sipuleucel-T does not result in the immediate declines in PSA that are common with other treatments for castration-resistant prostate cancer (CRPC). As a result, subtle nuances are involved in monitoring response to this treatment.
In general, monitoring patients treated with newer agents for CRPC is a major issue that emphasizes the need for surrogate endpoints, says Leonard G. Gomella, MD. Since PSA alone is not a good indicator of response, imaging when symptoms become apparent is the optimal approach for an asymptomatic man with CRPC treated with sipuleucel-T.
There’s a perplexing disconnect between PSA, radiographic progression, and overall survival when administering sipuleucel-T, believes Lawrence I. Karsh, MD. Clinical trials have shown a survival advantage favoring treatment but a biomarker to predict response has yet to be found. The lack of PSA decline and progression-free survival accompanied by improvement in overall survival after 6 months should be explained to the patient before administering sipuleucel-T, believes Evan Y. Yu, MD. Additionally, scanning should be delayed for 6 months or until symptoms occur, as the disease may appear worse initially. After 6 months, switching to a new therapy may only be warranted for patients with rapidly progressive disease, Yu believes.
At his practice, Mark C. Scholz, MD, administers sipuleucel-T as soon as metastases are detected followed quickly by abiraterone acetate (Zytiga) or enzalutamide (Xtandi). Scholz utilizes eplerenone (Inspra) in lieu of prednisone in combination with abiraterone, to address concerns over adverse reactions with sipuleucel-T. This approach seems safe and effective and addresses the issue of not being able to detect progression via PSA, Scholz states.