Cost-Effectiveness Analysis of Tyrosine Kinase Inhibitors for Patients with Advanced Gastrointestinal Stromal Tumors

Introduction The management of advanced gastrointestinal stromal tumors (GISTs) has been modified considerably by the availability of costly tyrosine kinase inhibitors (TKIs); however, the best therapeutic sequence in terms of cost and effectiveness remains unknown. Objective The aim of this study was to compare four potential strategies (reflecting the potential daily practice), each including imatinib 400 mg/day, as first-line treatment: S1 (imatinib(400)/best supportive care [BSC]); S2 (imatinib(400)/imatinib(800)/BSC); S3 (imatinib(400)/sunitinib/BSC); and S4 (imatinib(400)/imatinib(800)/sunitinib/BSC). Methods A Markov model was developed with a hypothetical cohort of patients and a lifetime horizon. Transition probabilities were estimated from the results of clinical trials. The analysis was performed from the French payer perspective, and only direct medical costs were included. Clinical and economic parameters were discounted, and the robustness of results was assessed. Results The least costly and effective strategy was S1, at a cost of a,notsign65,744 for 32.9 life months (reference). S3 was the most cost-effective strategy, with an incremental cost-effectiveness ratio (ICER) of a,notsign48,277/life-year saved (LYS). S2 was dominated, and S4 yielded an ICER of a,notsign363,320/LYS compared with S3. Sensitivity analyses confirmed the robustness of these results; however, when taking into account a price reduction of 80 % for imatinib, S2 and S4 become the most cost-effective strategies. Conclusion Our approach is innovative to the extent that our analysis takes into account the sequential application of TKIs. The results suggest that the S1 strategy is the best cost-effective strategy, but a price reduction of imatinib impacts on the results. This approach must continue, including new drugs and their impact on the quality of life of patients with advanced GISTs.