INSTITUTIONAL COMPLIANCE WITH TUMOR TREATING FIELDS FOR GLIOBLASTOMA

Tumor Treating Fields (TTFields) is a relatively new therapeutic intervention, which uses alternating electric fields to deliver low intensity, intermediate frequency current to solid brain tumors, thereby inhibiting mitosis. In the EF11 Phase III study in recurrent glioblastoma patient compliance, stratified by over or under 18 hours/day, for 28 days conferred a variable median survival benefit of 7.7 vs 4.5 months. In this study we report our institutional compliance in efforts to elucidate long term, >28 day, patient compliance in a clinical setting. After IRB approval we reviewed eleven patient TTFields compliance histories with recurrent and newly diagnosed GBM (age mean 55 ± 9 years). All patients underwent resection, chemotherapy (temozolomide +/- bevacizumab), and radiation therapy prior to TTField treatment. Duration of device use, hours of use per day, and reason for device discontinuation were reviewed with time to progression (TTP) determined by RECIST criteria. 6 patients met the recommended compliance of >18 hours per day (average 19.7 ± 1.0 hours/day), while 5 patients did not (averaging 11 ± 5 hours/day). 10 of 11 patients used TTFields for more than 100 consecutive days, with an average of 165 ± 85 days (range = 50 to 426 days). Patients discontinued use for a variety of reasons; death, insurance issues, and transition to hospice services following disease progression. After the start of TTFields therapy, the median TTP was 5.5 months (range 2 to 39 months). 5 patients with the longest TTP (>6 months) averaged >19.5 hours/day of treatment. While, 4 patients with the shortest TTP (3 months) averaged 11 hours/day. In a traditional clinical setting, many patients maintained compliance of >18 hours/day for an average of 165 days. In summary, we demonstrate that outside the scope of a clinical trial, high compliance with this device is a realistic and achievable goal.