Real-world dosing and drug costs with everolimus or axitinib as second targeted therapies for advanced renal cell carcinoma: A retrospective chart review in the US

Objective:To describe dosing patterns and to compare the drug costs per month spent in progression-free survival (PFS) among patients with advanced renal cell carcinoma (aRCC) treated with everolimus or axitinib following a first tyrosine kinase inhibitor (TKI).Methods:A medical record retrospective review was conducted among medical oncologists and hematologists/oncologists in the US. Patient eligibility criteria included: (1) age ≥18 years; (2) discontinuation of first TKI (sunitinib, sorafenib, or pazopanib) for medical reasons; (3) initiation of axitinib or everolimus as a second targeted therapy during February 2012-January 2013. Real-world dosing patterns were summarized. Dose-specific drug costs (as of October 2014) were based on wholesale acquisition costs from RED BOOK Online. PFS was compared between everolimus and axitinib using a multivariable Cox proportion hazards model. Everolimus and axitinib drug costs per month of PFS were compared using multivariable gamma regression models.Results:A total of 325 patients received everolimus and 127 patients received axitinib as second targeted therapy. Higher proportions of patients treated with axitinib vs everolimus started on a higher than label-recommended starting dose (14% vs 2%) or experienced dose escalation (11% vs 1%) on second targeted therapy. The PFS did not differ significantly between patients receiving everolimus or axitinib (adjusted hazard ratio (HR) = 1.16; 95% confidence interval [CI] = 0.73-1.82). After baseline characteristics adjustment, axitinib was associated with 17% ($1830) higher drug costs per month of PFS compared to everolimus ($12,467 vs $10,637; p < 0.001).Limitations:Retrospective observational study design and only drug acquisition costs considered in drug costs estimates.Conclusions:Patients with aRCC receiving axitinib as second targeted therapy were more likely to initiate at a higher than label-recommended dose and were more likely to dose escalate than patients receiving everolimus. With similar observed durations of PFS, drug costs were significantly higher-by 17% per month of PFS-with axitinib than with everolimus.