Cost Effectiveness of Ixabepilone Plus Capecitabine for Metastatic Breast Cancer Progressing After Anthracycline and Taxane Treatment

Purpose: Using data from a recent randomized trial, we evaluated the cost effectiveness of ixabepilone plus capecitabine versus capecitabine alone in patients with predominantly metastatic breast cancer considered to be taxane-resistant and previously treated with or resistant to an anthracycline.

Methods: We developed a stochastic decision-analytic model to represent data collected in the trial on medical resource use, health-related quality of life, and clinical outcomes. Estimates of overall survival were conditional on level of tumor response. We assigned monthly costs and utility weights according to periods defined by the duration of study treatment, time from discontinuation of the study drug until disease progression, and from progression until death and were specific to the level of response and receipt of subsequent therapy. Medical resources were valued in 2008 US dollars. We performed Monte Carlo simulations and sensitivity analyses to evaluate model uncertainty.

Results: Overall survival was significantly associated with level of tumor response (P < .001). Total costs were estimated at $60,900 for patients receiving ixabepilone plus capecitabine and $30,000 for patients receiving capecitabine alone. The estimated gain in life expectancy with ixabepilone was 1.96 months (95% CI, 1.36 to 2.64 months); the estimated gain in quality-adjusted survival was 1.06 months (95% CI, 0.09 to 2.03 months). The resulting incremental cost-effectiveness ratio was $359,000 per quality-adjusted life-year (95% CI, $183,000 to $4,030,000). In sensitivity analyses, the results were robust to changes in numerous inputs and assumptions.

Conclusion: Addition of ixabepilone to capecitabine adds approximately $31,000 to overall medical costs and affords approximately 1 additional month of quality-adjusted survival.