Cost-Effectiveness of Idelalisib-Rituximab for the Treatment of Relapsed/Refractory Chronic Lymphocytic Leukemia

Background: A significant survival prolongation was recently reported by adding idelalisib to rituximab (IR) compared with rituximab (R) in the treatment of relapsed/refractory chronic lymphocytic leukemia (CLL). No direct data are available about the relative safety and effectiveness of IR versus other commonly used treatments. The economic impact of novel treatments for CLL is still unknown and no study ever attempted in assessing the benefitfor-cost of IR as compared with the other available treatment options. Aim: To investigate the economic and clinical impact of IR in CLL Objective: To understand the potential clinical and economic advantage of IR in CLL patients who failed one prior treatment line (i.e. refractory to or relapsed after prior treatment lines), as compared with immunotherapy and chemoimmunotherapy. Methods: A treatment-sequence model was developed to estimate the incremental cost per QALY of IR versus R, bendamustine-rituximab (BR) and fludarabine cyclophosphamide-rituximab (FCR) in the second-line treatment setting (i.e. refractory to or relapsed after first-line therapy) in Italy. Tree Age software was used to simulate secondto-third line treatment sequences by a five-states Markov model: the model was run at monthly steps for 30 years. Probabilities of progression were obtained from published randomized and phase II studies (Furman, et al. 2014, Awan, et al. 2014, Fisher, et al. 2011): data were adapted to a second-line setting according to a fixed hazard ratio of 1.4 between subsequent lines. The analysis was performed in the perspective of the Italian national health-care system. Results: Base case analysis reported that IR improved quality-adjusted life expectancy by 1.91, 1.41 and 0.86 years as compared with R, BR and FCR. The incremental cost per quality-adjusted year (QALY) was €2,993, €16,045 and €28,045, respectively. The main drivers of the model were: time horizon, idelalisib unit cost and treatment duration. Deterministic and probabilistic sensitivity analyses showed that treatment with IR was cost-effective at conventional willingness-to-pay threshold (€40,000 per QALY). Conclusion: Based in this model, IR is a cost-effective option for CLL patients who deserve a second-line treatment.