THE "NEW" PROSTATE CANCER INFOLINK

Three months ago, James et al. presented the overall survival data from the most recently completed arm of the STAMPEDE trial at the annual meeting of the American Society of Clinical Oncology (ASCO).

At that time, they were able to tell us that there was an absolute overall survival benefit of 7 percent from treatment of the hormone-sensitive prostate cancer (HSPC) patients with androgen deprivation therapy (ADT) + abiraterone acetate (Zytiga) + prednisolone as compared to the standard of care (SOC) with ADT at just 3 years of follow-up, with an adjusted hazard ratio of 0.63 (p = 0.115 × 10^-7). These data encompassed all 1,917 men enrolled in this arm of the study. In and of itself, that is a set of very significant data.

At the annual meeting of the European Society of Medical Oncology (ESMO) in Madrid, which has now closed, James et al. provided an update to their data from this trial, focused on the outcomes of the patients diagnosed and enrolled with N0M0 disease as compared to the patients with N+M0 disease. (And once again we are indebted to Dr. Zachary Klaassen of the University of Toronto, Princess Margaret Cancer Centre, and to UroToday for their report on this presentation by Dr. James.)

In this arm of the STAMPEDE trial the, standard of care was ADT for 2+ years, and radiotherapy was

• Mandated for patients with N0M0 disease (unless contraindicated)
• Encouraged for patients with N+M0.

Stratified randomization allocated patients 1:1 to SOC with ADT or to SOC + abiraterone acetate + prednisolone.

Patients were continued on abiraterone treatment until there was evidence of PSA, radiological, and clinical progression, capped at 2 years in patients receiving radiotherapy. The definitive primary outcome measure was death from any cause and failure-free survival (FFS) was the intermediate primary outcome measure. Secondary outcomes included metastasis-free survival (MFS).

In Madrid, James et al. reported that

• 915 patients with NoM0 or N+M0 disease were randomized to SOC or SOC + abiraterone + prednisolone from November 2011 to January 2014.
• Among these 915 patients
  • Average (median) age was 67 years.
  • 81 percent were WHO performance status 1.
  • 42 percent had N+M0 disease.
  • Average (median) follow-up was 38 months.
• N0M0 patients who were not planned for radiotherapy (because they had been previously treated or because radiotherapy was contraindicated) were not excluded from subgroup estimates.
• Overall rates of FFS at 3 years were
  • Improved among N0M0 patients treated with SOC + abiraterone + prednisolone compared to SOC (hazard ratio [HR] = 0.14)
    • 80 percent among N0M0 patients treated with SOC
    • 98 percent among N0M0 patients treated with SOC + abiraterone + prednisolone
  • Improved among N+M0 patients treated with SOC + abiraterone + prednisolone compared to SOC (HR = 0.26)
• Estimated rates of MFS at 3 years were
  • Favorable for SOC + abiraterone + prednisolone in both subgroups, i.e.,
    • HR = 0.62 for patients with N0M0 disease.
    • HR = 0.47 for patients with N+M0 disease.
• Estimation of rates of overall survival in patients with N0M0 disease is not yet possible, with only 26 deaths among the N0M0 as of the time of the current analysis.

James et al. apparently concluded that early clinical outcomes for all M0 patients who were treated with SOC + abiraterone acetate + prednisolone were excellent, particularly for the N0M0 patients also planned for radiotherapy.

They also pointed out (as we have also reported elsewhere) that improvements of this magnitude in MFS among M0 patients should translate into a survival advantage.

Filed under: Diagnosis, Living with Prostate Cancer, Management, Treatment | Tagged: abirtaerone, ADT, hormone-sensitive, locally advanced, node-negative, node-positive, non-metastatic, outcome, STAMPEDE, survival |