CTNI-41. LONG-TERM SURVIVAL AND PATTERNS OF PROGRESSION IN PATIENTS WITH NEWLY DIAGNOSED GLIOBLASTOMA TREATED WITH OR WITHOUT TUMOR TREATING FIELDS (TTFIELDS) IN A REAL-WORLD SETTING

Abstract BACKGROUND Tumor Treating Fields therapy (TTFields) is an FDA-approved locoregional treatment for patients with newly diagnosed glioblastoma (ndGBM). Previous trial data showed the addition of TTFields to standard TMZ-based therapy to significantly improve overall survival (OS), but real-world data is lacking, particularly with long follow-up duration. Here, we report real-world survival and patterns of progression for patients with ndGBM treated with or without TTFields. METHODS Patients diagnosed with GBM and treated with standard of care therapy at the Medical College of Wisconsin between March 2015–March 2023 were included. Progression-free survival (PFS) and OS outcomes were assessed, and compared across groups who received or did not receive TTFields therapy during maintenance treatment. Patterns of disease progression were analyzed via anatomic assessment. Patients were followed through March 1, 2024. RESULTS A total of 210 patients (TTFields: n=110/52.4%; No-TTFields: n=100/47.6%) were included for analysis. Median age was 60 and 63 years for the TTFields and No-TTFields groups, respectively, with each group 43% female. Other baseline characteristics were consistent across groups. Median TTFields duration was 6.8 months (range: 1–94). OS was significantly improved for the TTFields group vs No-TTFields group (median OS: 21.6 months [18.4–24.8] vs 17.7 months [15.0–20.8]; HR 0.73 [95% CI: 0.54–0.99, P=0.042]). Median PFS was 12.1 months (10.3–14.4) vs 9.6 months (8.5–12.8) with HR 0.77 (95% CI: 0.58–1.02; P=0.071). 5-year OS was 17% (10–28) for the TTFields group, and 11% (5–22) for No-TTFields group. Patients treated with TTFields exhibited a higher rate of non-local progression compared with the No-TTFields group (28% vs 15%, [P=0.044]). CONCLUSIONS Analysis of patients from a large institutional dataset reveals an association between TTFields use and long-term survival benefit. Higher incidence of non-local patterns of progression among TTFields users is consistent with pivotal trial findings.