NCOG-41. REAL WORLD EXPERIENCE WITH TTFIELDS WITH EMPHASIS ON THERAPY COMPLIANCE

Abstract

Abstract Tumor Treating Fields (TTF) therapy has emerged as a significant adjunctive component in the treatment of high-grade tumors following its validation in the EF-14 trial in 2017. The incorporation of TTF therapy, alongside cyclic temozolomide (TMZ) therapy, has demonstrated enhanced outcomes in terms of PFS and OS when the useage exceeds 18 hours per day (75% compliance rate). Post-hoc analysis of the EF-14 trial has demonstrated that compliance rates exceeding 90% are associated with an additional benefit. Given the cost-intensive nature and significant constraints associated with the therapy, our objective is to generate real-world data on compliance through a retrospective analysis at a high-throughput academic center. Between June 2015 and February 2022, a total of 115 patients were prescribed TTFields as pa rt of their treatment for high-grade glioma. Mean age was 50y and mean preoperative Karnofsky Index 80-90. The average duration of therapy was 8 months. The majority of patients (74%) initiated therapy concurrently with 1st-line treatment, while only 25% managed to start concomitant to the first cycle of temozolomide. 16.7% started TTFields in the 2nd-line and 9.3% in the 3rd-line setting. Thirteen patients discontinued TTFields treatment within the first 3 months and were consequently excluded from further compliance analysis. Across the study cohort, the median compliance rate was 72% (SD 22%), with an average of 41 days of breaks observed. Compliance was highest during the first 3 cycles, with rates of 79%, 73%, and 72%, respectively. Linear regression analysis did not identify any predictors of compliance, including age at surgery, timing of therapy, duration of therapy, gender, and preoperative Karnofsky Index. These findings highlight the importance of monitoring and promoting adherence to TTFields therapy to maximize its potential benefits in the management of high-grade gliomas. Further strategies are warranted to expedite the start of therapy and improve long-term compliance.