Presentation (CTI)

OBJECTIVES: Many eligible patients stop Tumor Treating Fields (TTFields) treatment at first progression, due to a variety of reasons, which carries a survival cost. We estimated the overall survival benefit, measured as population life-years gained, of continuing TTFields treatment for eligible glioblastoma patients instead of discontinuing it, within a hypothetical US healthcare system of 70 million beneficiaries, to evaluate the benefit of treatment persistence.
METHODS: Overall survival (OS) was taken from Kaplan-Meier curves for two cohorts of TTFields-treated glioblastoma patients: those who continued therapy (persistent) and those who discontinued at progression. For each cohort, we estimated mean survival as the area under the curve and per-patient life-years gained as the difference between cohorts. We sized the eligible population with an epidemiological funnel (system beneficiaries × glioblastoma incidence × clinical eligibility) and reported a range for the treated population bounded below by observed real-world TTFields uptake (52% of clinically eligible patients) and above by treatment of all clinically eligible patients (100%). Funnel inputs assumed a GBM incidence of 3.28 per 100,000/year (CBTRUS 2018-2022) and a TTFields opt-in rate of 82% (TIGER trial, JCO 2024).
RESULTS: Patients who stayed on treatment after first progression lived 2.53 LYs compared to 2.03 LYs for those discontinuing at progression, a gain of 0.50. A four-parameter one-way sensitivity analysis (real-world uptake, per-patient OS, GBM incidence, and TTFields eligibility) was conducted to corroborate the results.
CONCLUSIONS: Continuing Tumor Treating Fields after first progression was associated with longer overall survival (0.50 life-years per patient) and progression-free survival (0.356 per patient) than discontinuing. These gains support the clinical value of continuing therapy for eligible glioblastoma patients as per label rather than stopping at progression.