Two treatment approaches — Zytiga (abiraterone acetate) plus prednisolone (AAP) or Taxotere (docetaxel) — provided patients with high-risk prostate cancer similar benefits when added to standard hormone deprivation therapy, according to data recently presented at the European Society for Medical Oncology (ESMO) 2017 Congress in Madrid, Spain.
While progression-free survival and other short-term measures slightly favored AAP, there was no difference in overall survival among patients treated with the two approaches. This leaves it up to oncologists to decide which treatment to opt for, researchers said, a decision that will likely be guided by availability and patient preferences.
The study, “Adding abiraterone acetate plus prednisolone (AAP) or docetaxel for patients (pts) with high-risk prostate cancer (PCa) starting long-term androgen deprivation therapy (ADT): directly randomised data from STAMPEDE (NCT00268476),” used data gathered in a Phase 2/3 trial called STAMPEDE.
In contrast to most other trials — which only compare a few treatments — this study includes six treatment approaches, of which some include several drugs. The therapies are compared to standard of care — androgen deprivation therapy — in patients with high-risk prostate cancer. Some patients also received radiotherapy as part of their standard regimen. All patients were newly diagnosed.
“Right now, oncologists and urologists want to know which combination is preferable, which is why we conducted this analysis,” Matthew Sydes, statistician, MRC Clinical Trials Unit at University College London and first study author, said in a press release.
The trial included 189 patients who were randomly assigned Taxotere treatment and 377 who were chosen to receive AAP. Earlier data from the trial showed that both approaches improved survival compared to standard of care alone. Now, they were compared to each other.
Findings showed that failure-free survival and progression-free survival were better in APP-treated patients than in those treated with Taxotere. APP-treated patients also had less metastatic progression and fewer had symptoms from cancer spreading to their bones, but these differences were not statistically significant.
At four years — which was the median follow-up time in the study — there was no difference in overall survival between the groups.
Safety also did not differ significantly between the approaches.
While researchers said that the number of patients is too small to be certain there is no difference between the therapies, the results could be used to guide physicians to make treatment choices.
“The individual trials suggested that abiraterone may have a larger effect on survival than docetaxel, but this did not translate into a clear advantage in this study. Both drugs provide a survival advantage over standard of care alone in men with high-risk prostate cancer beginning long-term hormone therapy,” said Nicholas D. James, chief investigator of STAMPEDE and consultant oncologist at the University of Birmingham and Queen Elizabeth Hospital in the U.K.
“This study suggests that starting with either drug is acceptable and choice may depend on availability,” he added.
Sydes also underscored that it was the unique platform nature of the trial that allowed for the comparison, a statement that ESMO’s Cora N.Sternberg — chief of the Department of Medical Oncology at San Camillo Forlanini Hospital in Italy — also endorsed.
“The STAMPEDE trial has a unique design and has prospectively studied more than 9,000 patients with high risk or metastatic hormone sensitive prostate cancer compared to the standard of care,” Sternberg said.