Tumor treating fields therapy in patients with newly diagnosed glioblastoma and poor performance status: Real-world analysis of patients treated in the US.

2044 Background: TTFields therapy is an FDA-approved treatment for patients with newly diagnosed glioblastoma, showing benefit in overall survival (OS) when added to maintenance temozolomide (TMZ). While device effectiveness was demonstrated regardless of performance status (PS) in the EF-14 study, only patients with Karnofsky Performance Status (KPS) of ≥70 were eligible for the study. This study investigates real-world outcomes of patients with newly diagnosed glioblastoma and poor PS who were treated with TTFields. Methods: Electronic medical records of patients initiating treatment with TTFields in the US commercial setting between January 1, 2019 and December 31, 2021 were accessed via the xCures real-world data platform and Novocure systems, from which clinical data were extracted. To be included in the analysis, patients needed to have a documented new diagnosis of glioblastoma occurring within 180 days of initiating TTFields and have KPS ≤60 or ECOG PS ≥2 within 3 weeks of treatment initiation. IDH status was ascertained where data were available. Device usage was calculated as the average percentage of time the device was used within the first 3 months of therapy, as recorded by the device log files. Patients were divided into high and low usage groups. High usage was defined as usage ≥50% and treatment duration ≥30 days, and low usage as usage <50% or treatment duration <30 days, excluding patients with a death event within 30 days of initiating TTFields. Demographics, disease characteristics, and survival outcomes were evaluated. Data cutoff for analysis was Jan 7, 2026. Results: The study included 306 patients, of whom 198 (65%) were high users and 108 (35%) low users. Baseline characteristics were balanced between the two groups. Although most patients had KPS of 60 or ECOG PS of 2 (n=204, 67%), the study included 102 patients (33%) who had KPS ≤50 or ECOG PS ≥3. The entire cohort had median OS from diagnosis of 13.3 months (95% CI, 12.4–14.5). Median OS was 14.1 months (95% CI, 12.8–15.9) in the high-use group compared with 11.9 months (95% CI, 9.6–13.3) in the low-use group (HR, 0.69 95% CI, 0.53–0.89; P=0.005). Similar results were observed regardless of the performance scale utilized. Further subgroup analysis showed a consistent usage effect for patients ≥65 and <65 years of age (HR, 0.71 0.49–1.02, P=0.067 and HR, 0.69 0.47–1.00, P=0.049, respectively). Conclusions: Patients with newly diagnosed glioblastoma and poor performance status receiving TTFields therapy in the real-world setting appear to have favorable survival when compared with historical data. Usage is associated with improved survival in this population, including among elderly patients for whom treatment options are limited. Additional studies examining TTFields in this high-need population with limited trial options are warranted.