The objective of this study was to conduct an indirect treatment comparison between cabazitaxel, abiraterone and enzalutamide to determine the clinical efficacy and safety of cabazitaxel relative to comparators in the treatment of patients with metastatic castrate-resistant prostate cancer who progress on docetaxel-based therapies.
A systematic literature review was conducted to inform the network meta-analysis of cabazitaxel, abiraterone and enzalutamide. Due to a lack of head-to-head trials, studies with a comparator arm of best supportive care were included in the analysis. Overall survival, progression-free survival, and adverse events were compared within both Bayesian and Frequentist frameworks. The ratios for survival outcomes were estimated using hazard ratios (HR), and the ratios for adverse events between groups were estimated using odds ratios (ORs); uncertainty was reported as 95% confidence (Frequentist) and credible (Baysesian) Intervals.
Three of thirteen trials identified for abstraction were relevant for analyses. Median overall survival was not statistically significantly different for abiraterone (HR = 1.04; 95% CI = 0.83-1.28) or enzalutamide (HR = 0.88; 95% CI = 0.69-1.11) when compared to cabazitaxel in the Bayesian analysis. Anaemia (OR = 3.71; 95% CI = 1.01-10.44), diarrhoea (OR = 16.60; 95% CI = 1.41-75.31) and haematuria (OR = 3.88; 95% CI = 1.03-10.09) were more likely to occur in the cabazitaxel group than the abiraterone group, while pyrexia risk was higher in cabazitaxel compared to enzalutamide (OR = 36.23; 95% CI = 1.14-206.40). Frequentist analyses produced similar results.
The scarcity of clinical studies and lack of a common comparator limited analyses. The adverse event results must be interpreted with caution as many were based on small numbers. The results from this analysis indicate comparable survival outcomes and adverse event profiles. As these pivotal studies may not reflect the contemporary treatment landscape and patient profiles, additional research, including head-to-head clinical trials and real world observational studies, should be conducted to further elucidate the beneficial effects of these therapies.
Fryzek JP, Reichert H, Summers N, Townes L, Deuson R, Alexander DD, Vanderpuye-Orgle J. Indirect treatment comparison of cabazitaxel for patients with metastatic castrate-resistant prostate cancer who have been previously treated with a docetaxel-containing regimen. PLoS One. 2018 Apr 11;13(4):e0195790.