Cost-effectiveness of 3-years of adjuvant imatinib in gastrointestinal stromal tumors (GIST) in the United States

Abstract

Background:

Recent clinical trial data have demonstrated that 3 years vs 1 year of adjuvant imatinib therapy for patients with surgically resected Kit+ Gastrointestinal Stromal Tumors (GIST) leads to a significant improvement in recurrence-free survival and overall survival. This study assesses the cost-effectiveness of treating patients with 3 years vs 1 year of imatinib from a US payer’s perspective.

Methods:

A Markov model was developed to predict GIST recurrence and treatment costs. Patients enter the model after surgery and transition among three health states: free of recurrence, recurrence, and death. Recurrence, mortality, costs, and utilities were derived from clinical trial and published literature. Expected costs and quality-adjusted life years (QALYs) were estimated and discounted at 3%/year. Deterministic and probabilistic sensitivity analyses were conducted.

Results:

Patients receiving 3 years of imatinib had higher QALYs (8.53 vs 7.18) than those receiving 1 year of imatinib. Total lifetime per-patient cost was $302,100 for 3 years vs $217,800 for 1 year of imatinib. Incremental cost effectiveness ratio of 3 years vs 1 year of imatinib was $62,600/QALY. Model results were sensitive to long-term rate of GIST recurrence (beyond 5 years) and cost of imatinib. At a threshold of $100,000/QALY, 3 years vs 1 year of imatinib was cost-effective in 100% of simulations.

Limitations:

The model is a simplified representation of disease natural history and may not account for all possible health states and complications associated with disease. Resource utilization on treatment was estimated using the resource use data from previous trials, therefore calculated medical costs might be over-estimated compared to the real-world setting.

Conclusions:

Model results suggest that treatment with 3 years vs 1 year of imatinib is cost-effective at a $100,000/QALY threshold. Clinical and economic results suggest treating surgically resected Kit+ GIST patients with 3 years of imatinib would result in improved quality-adjusted survival.

Keywords::

• GIST
• Cost-effectiveness
• Imatinib

Transparency

Declaration of funding

Funding for this research was provided by Novartis Pharmaceuticals, Florham Park, NJ, USA. The data and methodology used in the manuscript was not proprietary in nature and the publication of this paper is not contingent on the sponsor’s approval.

Declaration of financial/other relationships

Myrlene Sanon, Douglas C. A. Taylor, and Anju Parthan have disclosed that they have a compensated consultant/advisory role at OptumInsight, a company sponsored by Novartis to conduct this study. John Coombs and Medha Sasane have disclosed that they are employees of Novartis. Marc Paolantonio has disclosed that he was an employee of Novartis at the time this study was conducted.

Acknowledgments

No assistance in the preparation of this article is to be declared.