Practice Update: Oncology

15 / 36

Abiraterone Acetate Plus Prednisolone Comparable to
Docetaxel in High-Risk Prostate Cancer
Patients beginning long-term androgen deprivation therapy (ADT) showed similar outcomes from the addition of
abiraterone acetate plus prednisolone vs docetaxel, according to new results from the Systemic Therapy in Advancing
or Metastatic Prostate cancer: Evaluation of Drug Efficacy (STAMPEDE) trial. The findings were reported at the European
Society for Medical Oncology (ESMO) 2017 Congress, from September 8–12.
Matthew R. Sydes, MSc, with the
University College London, UK,
stated that oncologists and urol-
ogists want to know which combination is
preferable, which was the basis for con-
ducting the trial.
The STAMPEDE trial, initiated in 2005, is
designed to investigate a number of new
treatments combined with long-term hor-
monal therapy in patients with high-risk
prostate cancer.
In 2016, STAMPEDE found that docetaxel
improved survival vs standard of care (haz-
ard ratio 0.78). In June 2017, the trial found
that abiraterone acetate + prednisolone
also improved survival vs the same stand-
ard of care (hazard ratio 0.63).
The analysis used prospectively collected
data from STAMPEDE to directly compare
patients randomized to docetaxel or abi-
raterone acetate plus prednisolone while
both arms of the trial were recruiting. The
randomizations overlapped between 2011
and 2013. The comparison included 566
patients (189 randomized to docetaxel
and 377 to abiraterone acetate plus
prednisolone, both in addition to andro-
gen-deprivation therapy [+ radiotherapy in
some patients]).
The primary outcome of overall survival
was comparable between the two treat-
ments. However, estimates of treatment
effect clearly favored abiraterone acetate +
prednisolone with hazard ratios of 0.51 and
0.65, respectively, in early outcome meas-
ures of failure-free and progression-free
survival.
Estimates of treatment effect for late out-
come measures of metastatic progression
and freedom from symptomatic skeletal
events favored abiraterone acetate + pred-
nisolone, but the treatment groups did not
differ statistically significantly.
Mr. Sydes noted that the comparison was
underpowered, but it is the only data that
compares docetaxel and abiraterone
directly in this setting.
Coinvestigator Nicholas D. James, MD, of
the University of Birmingham and Queen
Elizabeth Hospital, Birmingham, UK, stated
in a written release that, the individual tri-
als suggested that abiraterone may exert
a larger effect on survival than docetaxel,
but this larger effect did not translate into
a clear advantage in this study.
He added that both drugs provided a sur-
vival advantage over standard of care
alone in men with high-risk prostate can-
cer who begin long-term hormone therapy.
The results suggested that starting with
either drug is acceptable and choice may
depend on availability.
Commenting for ESMO, Cora N. Stern-
berg, MD, of San Camillo Forlanini Hospital,
Rome, Italy, stated that the STAMPEDE trial
confers a unique design and has prospec-
tively studied more than 9000 patients with
high risk or metastatic hormone-sensitive
prostate cancer vs the standard of care. By
2025 it will have reported the results of 10
randomized clinical trials.
She added that this comparison offered
strong evidence for the combination of
standard of care in addition to abiraterone
acetate + prednisolone vs standard of care
alone in terms of failure-free survival and
progression-free survival and less strong
evidence in terms of metastases-free sur-
vival and skeletal related events. There
was no difference in survival with standard
of care in addition to docetaxel compared
to standard of care in addition to abirater-
one acetate + prednisolone, she noted.
Dr. Sternberg pointed out that the toxic-
ity profiles were quite different in the two
trials. Results with abiraterone acetate +
prednisolone were consistent with those
of the LATITUDE trial, which also favored
abiraterone acetate + prednisolone over
standard of care in high-risk patients.
According to Dr. Sternberg, both STAM-
PEDE randomized trials support starting
hormonal therapy plus either abirater-
one acetate + prednisolone or 6 cycles of
docetaxel, with similarly low percentages
of grade 3 or 4 toxicities with the two treat-
ments at 1 and 2 years. Physicians will base
their choice of therapy on availability and
patient characteristics and preferences,
she added.
Regarding the need for further studies, Dr.
Sternberg stated that cardiovascular fol-
low-up will be important in patients taking
abiraterone acetate + prednisolone.
PracticeUpdate Editorial Team
© ESMO 2017 Congress
ESMO 2017 15
VOL. 1 • NO. 3 • 2017