The Additional Costs per Month of Progression-Free Survival and Overall Survival: An Economic Model Comparing Everolimus with Cabozantinib, Nivolumab, and Axitinib for Second-Line Treatment of Metastatic Renal Cell Carcinoma

BACKGROUND: When considering optimal second-line treatments for metastatic renal cell carcinoma (mRCC), clinicians and payers seek to understand the relative clinical benefits and costs of treatment. OBJECTIVE: To use an economic model to compare the additional cost per month of overall survival (OS) and of progression-free survival (PFS) for cabozantinib, nivolumab, and axitinib with everolimus for the second-line treatment of mRCC from a third-party U.S. payer perspective. METHODS: The model evaluated mean OS and PFS and costs associated with drug acquisition/administration; adverse event (AE) treatment; monitoring; and postprogression (third-line treatment, monitoring, and end-of-life costs) over 1- and 2-year horizons. Efficacy, safety, and treatment duration inputs were estimated from regimens’ pivotal clinical trials; for everolimus, results were weighted across trials. Mean 1- and 2-year OS and mean 1-year PFS were estimated using regimens’ reported OS and PFS Kaplan-Meier curves. Dosing and administration inputs were consistent with approved prescribing information and the clinical trials used to estimate efficacy and safety inputs. Cost inputs came from published literature and public data. Additional cost per additional month of OS or PFS was calculated using the ratio of the cost difference per treated patient and the corresponding difference in mean OS or PFS between everolimus and each comparator. One-way sensitivity analyses were conducted by varying efficacy and cost inputs. RESULTS: Compared with everolimus, cabozantinib, nivolumab, and axitinib were associated with 1.6, 0.3, and 0.5 additional months of PFS, respectively, over 1 year. Cabozantinib and nivolumab were associated with additional months of OS compared with everolimus (1 year: 0.7 and 0.8 months; 2 years: 1.6 and 2.3 months; respectively); axitinib was associated with fewer months (1 year: -0.2 months; 2 years: -0.7 months). The additional costs of treatment with cabozantinib, nivolumab, or axitinib versus everolimus over 1 year were $34,141, $19,371, and $17,506 higher, respectively. Everolimus had similar OS and lower costs compared with axitinib. The additional cost per month of OS was $48,773 for cabozantinib and $24,214 for nivolumab versus everolimus. The additional treatment cost with cabozantinib, nivolumab, or axitinib versus everolimus for each additional month of PFS was estimated at $21,338, $64,570, and $35,012, respectively. Over 2 years, the additional costs per additional month of OS for nivolumab and axitinib versus everolimus were similar to the 1-year analysis; for cabozantinib, the cost was lower. Results were sensitive to changes in mean OS, mean PFS, therapy duration, and drug costs estimates. CONCLUSIONS: Everolimus for second-line mRCC was associated with similar OS and lower costs compared with axitinib over 1- and 2-year horizons. The additional cost per additional month of OS and PFS associated with cabozantinib or nivolumab versus everolimus creates a metric for evaluating the cost of second-line therapies in relation to their respective treatment effects.