mCRPC patients with lower PSA levels respond better to sipuleucel-T

According to yet another re-analysis of data from the randomized Phase III trial that led to the original approval of sipuleucel-T (Provenge®), “the … treatment effect appeared greater with decreasing baseline PSA” in men with metastatic, castrate-resistant prostate cancer (mCRPC).

The relevant data supporting this assertion can be found in a paper by Schellhammer et al., just published on line in Urology, and in a commentary on this paper that appears on the MedwireNews web site.

According to Schellhammer and his colleagues:

  • The patient’s PSA levels were the strongest baseline prognostic factor for response to sipuleucel-T (P < 0.0001) among the men randomized to treatment with the active drug.
  • The hazard ratios (HR) for overall survival were
    • 0.51 for patients in the lowest baseline PSA quartile (≤ 22.1 ng/ml)
    • 0.84 for patients in the highest baseline PSA quartile (> 134 ng/ml)
  • Estimated improvements in median survival were
    • 13.0 months for patients in the lowest baseline PSA quartile
    • 2.8 months for patients in the highest baseline PSA quartile.
  • Estimated 3-year survival was
    • 62.6 percent for patients in the in the lowest baseline PSA quartile
    • 41.6 percent for the control patients

These findings are not exactly surprising. One would reasonably expect men with a lower burden of metastatic disease to have a greater chance of responding well to immunotherapeutic interventions for the treatment of metastatic prostate cancer, and PSA levels commonly offer a reasonable (if imperfect) measure of cancer burden in men with advanced forms of prostate cancer. The approved indication for sipuleucel-T is “for the treatment of asymptomatic or minimally symptomatic metastatic castrate resistant (hormone refractory) prostate cancer.”

One Response

  1. Beware: If under (say) 70, longevity is quite short; over 7o, this procedure extensd longevity some; read both articles related to treatment and they admit their error.

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