Practice Update: Oncology

ESMO 2017 15

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. M atthew R. Sydes, MSc, with the University College London, UK, stated that oncologists and urol- a larger effect on survival than docetaxel, but this larger effect did not translate into a clear advantage in this study.

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.

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

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

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VOL. 1 • NO. 3 • 2017