Abstract LB-162: Treating elderly glioblastoma patients &gt; 65 years with TTFields - a cost-effectiveness perspective
Authors: Guzauskas Gregory F. , Pollom Erqi L. , Stieber Volker W. 
Published: August 2019

Abstract
Objective: To compare the incremental cost effectiveness results of treating elderly Glioblastoma (GBM) patients age 65 years or older with tumor treating fields (TTFields) and maintenance Temozolomide (TMZ) versus maintenance TMZ alone with reported willingness to pay thresholds for cancer patients.
Background: Glioblastoma is the most aggressive form of primary brain cancer in adults. Around half of the patients in the real-world setting are diagnosed at the age of 65 and older. The EF-14 trial demonstrated significantly increased five-year overall survival results for all patients in the TTFields plus TMZ group, with the subgroup of patients age 65 and older showing the greatest survival benefit from TTFields plus TMZ treatment. We report on the cost-effectiveness of adding TTFields from a U.S. health system perspective and recent literature on willingness to pay for cancer patients.
Methods: We calculated the Incremental cost effectiveness ratio for patients above 65 years using TTFields as part of their first line treatment. Patient outcomes were simulated using a 3-state area under the curve model including alive with stable disease, progressed disease, and death. Survival was modeled over a lifetime horizon by integrating the 5-year survival results for elderly patients reported in the EF-14 trial with long-term GBM epidemiology data and U.S. background mortality rates. Data on patient utilities used to calculate quality-adjusted life years (QALYs) were based on a previous analysis of GBM-specific health-state preferences. Frequency of adverse events associated with TTFields and TMZ were derived from the EF-14 trial for the patients over 65 years. Costs for adverse events and supportive care cost estimates were used according to published literature. Future survival benefits and costs were discounted to present value at a rate of 3%. One-way and probabilistic sensitivity analyses were performed to assess result uncertainty due to parameter variability. A literature research with specific focus on willingness to pay threshold for elderly patients was conducted and the results of the ICER for using TTFields are discussed and compared to the literature.
Results: Willingness to pay thresholds is rarely reported separately for older patients. The recent literature reports a large scale of willingness to pay thresholds for cancer patient in general. For patients treated with TTFields and maintenance TMZ the resulting ICER was $109,500 per life year gained (LYG) and $142,400 per QALY gained. The probability of TTFields being cost-effective was 85% at a willingness-to-pay threshold of $200,000 per QALY.
Conclusions: TTFields therapy, evaluated at its full list price, demonstrated a high probability of cost-effectiveness at willingness-to-pay thresholds reported in economic literature for the United States. Treating newly diagnosed GBM patients over 65 years of age with TTFields and TMZ has the potential to increase mean lifetime survival and quality-adjusted survival substantially compared to treatment with TMZ alone. These results indicate that patients over age 65 may not only benefit from TTFields treatment more than other subgroups, but also that their treatment may be more cost-effective.
Citation Format: Gregory F. Guzauskas, Erqi L. Pollom, Volker W. Stieber. Treating elderly glioblastoma patients &gt; 65 years with TTFields - a cost-effectiveness perspective [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-162.