The first head-to-head comparison of docetaxel and abiraterone acetate for high-risk prostate cancer patients starting long-term hormone therapy found benefit with both treatments when added to androgen deprivation therapy (ADT). Treatment decisions may come down to specific toxicities, which differ between the treatments.
The large STAMPEDE trial previously found that both docetaxel and abiraterone improved outcomes when compared with placebo. “Right now, oncologists and urologists want to know which combination is preferable, which is why we conducted this analysis,” said study author Matthew Sydes, MSc, a statistician at University College London.
Sydes and colleagues presented results of a new analysis of a subset of STAMPEDE patients (abstract LBA 31) at the European Society for Medical Oncology (ESMO) 2017 Congress, held September 8–11 in Madrid. They included patients who were randomized to the two treatments while both arms were recruiting, representing the last 189 of 592 docetaxel patients and the first 377 of 960 abiraterone patients.
Most patients (76%) had a Gleason score of 8 to 10, and most (79%) had a World Health Organization (WHO) performance status of 0. The median age in the cohort was 66 years.
After a median of 4 years of follow-up, 45 docetaxel patients and 111 abiraterone patients had died. The hazard ratio (HR) for survival favored docetaxel, but did not reach significance, at 1.16 (95% CI, 0.82–1.65).
Meanwhile, there was significant improvement with abiraterone with regard to failure-free survival, with an HR of 0.51 (95% CI, 0.39–0.67), and progression-free survival, with an HR of 0.65 (95% CI, 0.48–0.88). Metastasis-free survival favored abiraterone but was not significant, with an HR of 0.77 (95% CI, 0.57–1.03), and the same was true of skeletal-related events, with an HR of 0.83 (95% CI, 0.55–1.25).
Total toxicity rates were similar, with grade 3, 4, and 5 adverse events occurring in 36%, 13%, and 1% of docetaxel patients, and in 40%, 7%, and 1% of abiraterone patients.
“The comparison was of course underpowered, but it is the only data we have to directly compare docetaxel and abiraterone in this setting,” Sydes said.
Cora N. Sternberg, MD, of San Camillo-Forlanini Hospital in Rome, commented on the study. “Toxicities associated with chemotherapy for six cycles will dominate decisions about upfront docetaxel,” she said. “Toxicities associated with [abiraterone] are also likely to influence decisions. Physicians will base their choice of therapy on availability and patient characteristics and preferences.”