Abstract CT100: Tumor treating fields (TTFields) on health-related quality of life (HRQoL) in ndGBM: An exploratory analysis of the EF-14 phase III trial

TTFields are a novel treatment modality based on home-use medical device which continuously delivers alternating electric fields to the region of the tumor. These fields selectively interfere with a number of cellular processes during the mitotic cycle, such as the assembly of the mitotic spindle, leading to apoptosis. In the EF-14 phase III study in newly diagnosed glioblastoma, TTFields added to maintenance temozolomide led to a significant increase in overall survival, as well as in the 5-year survival rate compared to patients treated with temozolomide alone. It was previously reported that the addition of TTFields to maintenance temozolomide did not negatively impact nine prespecified HRQoL scales except for an expected increase in itchy skin, and in addition resulted in a significant delay in the increase of HRQoL pain assessment. Here we present an exploratory analysis of the remaining EORTC QLQ C-30 and BN-20 HRQoL scales. Methods HRQoL was a predefined secondary endpoint in the EF-14 study, measured by collecting the EORTC QLQ-C30 and BN20 questionnaires at baseline and every 3 months thereafter. HRQoL was assessed for the remaining HRQoL scales except for the prespecified and previously reported nine preselected scales: global health, physical, cognitive, role, social and emotional functioning, itchy skin, pain, and leg weakness. Mean changes from baseline scores were evaluated, as well as significant changes in scores over time (>10 points) using a repeated measures test. Moreover, deterioration-free survival and time to deterioration in HRQoL were assessed for each scale, as well as the percentage of patients with stable/improved HRQoL compared to baseline. Results No statistically or clinically significant decline in any of the exploratory HRQoL scales was seen in the repeated measures analysis or in time to deterioration. A significantly larger proportion of patients treated with TTFields compared to control patients reported stable/improved bladder control (63.6% Vs. 46.8%, p=0.001) and diarrhea (60.6% vs. 43.7%, p=0.001) compared to baseline. The deterioration-free survival for diarrhea, future uncertainty and headaches was significantly delayed in TTFields/temozolomide treated patients compared to those treated with temozolomide alone (HR 0.68, 0.71 and 0.67, respectively, p