Axitinib, cabozantinib, or everolimus in the treatment of prior sunitinib-treated patients with metastatic renal cell carcinoma: results of matching-adjusted indirect comparison analyses

BACKGROUND: In the absence of head-to-head trials comparing axitinib with cabozantinib or everolimus, the aim of this study was to conduct an indirect comparison of their relative efficacy in patients with metastatic renal cell carcinoma (mRCC), using data from the AXIS and METEOR trials. METHODS: Progression-free survival (PFS) and overall survival (OS) in prior sunitinib-treated patients with mRCC were compared by conducting matching-adjusted indirect comparison (MAIC) analyses, including base-case and sensitivity analyses. Individual patient-level data from prior sunitinib-treated patients who received axitinib in AXIS were weighted to match published baseline characteristics of prior sunitinib-treated patients who received either cabozantinib or everolimus in METEOR. RESULTS: There was no statistically significant difference in PFS (aHR [adjusted hazard ratio] = 1.15 [CI: 0.82–1.63]) and OS (aHR = 1.00 [CI: 0.69–1.46]) between axitinib versus cabozantinib in the base-case analysis. In the sensitivity analysis, PFS (aHR = 1.39 [CI: 1.00–1.92]) and OS (aHR = 1.35 [CI: 0.95–1.92]) were shorter for axitinib compared with cabozantinib; however, the OS difference was not statistically significant. Axitinib was associated with significantly longer PFS compared with everolimus in the base-case (aHR = 0.53 [CI: 0.36–0.80]) and sensitivity analyses (aHR = 0.63 [CI: 0.45–0.88]), respectively. Results suggested an OS benefit for axitinib versus everolimus in base-case analyses (aHR = 0.63 [CI: 0.42–0.96]); however, the difference in OS in the sensitivity analysis was not statistically significant (aHR = 0.84 [CI: 0.59–1.18]). CONCLUSIONS: MAIC analyses suggest PFS and OS for axitinib and cabozantinib are dependent on the Memorial Sloan Kettering Cancer Center definition used; in the base-case analysis, there was no significant difference in PFS and OS between axitinib and cabozantinib. In the sensitivity analysis, PFS in favour of cabozantinib was significant; however, the trend for prolonged OS with cabozantinib was not significant. For axitinib and everolimus, MAIC analyses indicate patients treated with axitinib may have an improved PFS and OS benefit when compared to everolimus. Disparities between the base-case and sensitivity analyses in this study underscore the importance of adjusting for the differences in baseline characteristics and that naïve indirect comparisons are not appropriate.