P14.112 Long-term application of TTFields in glioblastoma: a multiple-case study

Abstract

Abstract BACKGROUND Tumor treating fields (TTFields) is an antimitotic cancer therapy that utilizes low-intensity, intermediate-frequency alternating electrical fields to treat glioblastoma (GBM). Increased compliance with TTFields is independently prognostic for improved survival and was correlated with significantly improved overall and progression-free survival versus temozolomide (TMZ) alone. We present two exemplary cases of primary GBM treated with TTFields on long-term and adjuvant chemotherapy to explore treatment adherence, feasibility and safety issues. MATERIAL AND METHODS We present case details of two patients from our comprehensive cancer center, both of whom have primary GBM and are long-term TTFields users. One patient began TTFields at first diagnosis whilst the other had already survived to two years at the time of TTFields commencement. Their histories and disease status under continuous, ongoing TTFields therapy with concomitant, extended chemotherapy are explored. RESULTS Patient A is a 52-year-old male with IDH1-wildtype, MGMT promoter-methylated GBM. He began TTFields 24 months after initial diagnosis. Before starting TTFields, he had two resections, one owing to early locoregional progression, and had underwent standard, dual radiochemotherapy and started adjuvant TMZ. He has now completed 931 days of treatment with an average daily usage of 82% and has survived 55 months from first diagnosis. Since beginning TTFields, he has undergone a further two resections and another radiotherapy course. His chemotherapy regime has been modified several times, from standard-dose to dose-intensified TMZ, then later switched to lomustine and irinotecan-containing protocols. Patient B is a 68-year-old male, also with IDH1-wildtype, MGMT promoter-methylated GBM. He began TTFields six months after first diagnosis and after one tumor resection, concomitant radiochemotherapy and initiation of long-term TMZ therapy. He has now undergone 636 days of TTFields treatment with an average daily usage of 74%. In addition, 28 cycles of TMZ have been completed. CONCLUSION During a mean treatment duration of 784 days and alongside extended-course adjuvant chemotherapy, TTFields was well tolerated. Both patients are alive and still receiving treatment. Compliance has remained within the target range. Significant adverse events or treatment interruptions have not occurred. The patients have remained symptomatically stable and their quality of life has been maintained.