Small molecule targeted therapies for the second-line treatment for metastatic renal cell carcinoma: a systematic review and indirect comparison of safety and efficacy.

backgroundPatients with metastatic renal cell carcinoma (mRCC) and a good performance status typically receive an anti-vascular endothelial growth factor receptor (VEGFR) TKI (sunitinib or pazopanib) as initial therapy. Upon disease progression or intolerance, there are four orally administered agents approved in the second-line setting (including cytokine-refractory). However, head-to-head comparative trial data are limited. In this study, an indirect statistical comparison of safety and efficacy was undertaken between axitinib, sorafenib, pazopanib and everolimus in second-line therapy mRCC.

methodsA systematic review of major databases was conducted from January 2005 to June 2013 for randomized controlled trials (RCTs) evaluating at least one of the four agents in second-line mRCC. Bayesian mixed treatment comparison models were fitted to assess relative effectiveness on multiple endpoints such as objective response rates, dose-limiting grade III/IV toxicities, treatment discontinuations and progression-free survival (PFS).

resultsFour RCTs met the inclusion criteria. All four agents seem able to induce tumor shrinkage and to provide patients with a clinically meaningful PFS benefit. Axitinib was superior to pazopanib [hazard ratio (HR) 0.64; 95 % credible interval (95 % Crl) 0.42-0.96] and sorafenib (HR 0.70; 95 % Crl 0.57-0.87) in terms of PFS. However, axitinib was associated with an elevated risk of fatigue and to a lesser extent stomatitis.

conclusionsKeeping in mind the caveats associated with cross-trial statistical comparisons, axitinib provides superior PFS relative to pazopanib and sorafenib. Everolimus, an mammalian target of rapamycin inhibitor, is mechanistically distinct from the other agents and remains a useful option for patient's post-anti-VEGFR TKI failure.