- A subanalysis of the STAMPEDE trial found that docetaxel and abiraterone acetate plus prednisolone equally improved survival when added to long-term hormone therapy in patients with high-risk prostate cancer.
- Either drug is acceptable and choice may depend on availability.
Why this matters
- Early outcome measures of failure-free survival and progression-free survival treatment effect in STAMPEDE favoured abiraterone acetate plus prednisolone with HRs of 0.51 and 0.65, respectively.
- Also, the estimates for late outcome measures of freedom from metastatic progression and freedom from symptomatic skeletal events favoured abiraterone acetate plus prednisolone but the differences were not statistically significant.
- In order to clarify which combination is preferable, the analysis presented at ESMO used prospectively collected data to directly compare the 2 treatments while both arms of the trial were recruiting.
- The analysis included 566 patients randomly assigned to receive docetaxel (n=189) and AAP (n=377), on top of standard hormonal therapy (and radiotherapy for some patients).
- Groups were well balanced with 342 (60%) M1; 429 (76%) Gleason 8-10; 449 (79%) WHO PS 0; median age of 66 years; and prostate-specific antigen level of 56 ng/mL.
- Median follow-up was 4 years.
- Funding: Cancer Research UK, Medical Research Council, Janssen; Astellas, Clovis Oncology, Novartis, Pfizer, Sanofi-Aventis.
- The estimate for the primary outcome of overall survival was a HR of 1.16.
- The difference between the 2 treatments was not statistically significant, with confidence intervals giving estimates favouring both treatments.
- The study is underpowered, further analyses are needed and more data will come from the ongoing trials.
- Professor Nicholas D. James (University of Birmingham), Chief Investigator of STAMPEDE said: “The individual STAMPEDE trials suggested that abiraterone may have a larger effect on survival than docetaxel, but this did not translate into a clear advantage in this analysis. Both drugs provide a survival advantage over standard of care. This study suggests that starting with either drug is acceptable and choice may depend on availability.”