Epithelioid glioblastoma (EGBM, classified as glioblastoma, IDH wild type, grade 4 according to the fifth edition of the World Health Organization (WHO) Classification of Tumors of the Central Nervous System (CNS) (WHO CNS5)) is a highly aggressive malignancy, with a median progression-free survival (mPFS) of about 6 months in adults. The application of tumor-treating fields (TTFields, possessing anti-cancer capabilities via anti-mitotic effects) in the maintenance of temozolomide (TMZ) chemotherapy showed a benefit for prolonging the mPFS of newly diagnosed glioblastoma (GBM) for patients for up to 6.9 months in the EF-14 clinical trial (NCT00916409). However, studies focusing on the effect of TTFields in EGBM treatment are very limited due to the rarity of EGBM. Here, we have reported a case of a 28-year-old male (recurrent left-sided limb twitching for 1 month and dizziness for 1 week) diagnosed with EGBM. A right frontal lobe occupancy was detected by magnetic resonance imaging (MRI), and a total tumor resection was performed. Meanwhile, a postoperative histopathology test, including immunohistochemistry and molecular characterization, was conducted, and the results revealed a BRAF V600E mutation, no co-deletion of 1p and 19q, and negative O-6-methylguanine DNA methyltransferase (MGMT) promoter methylation. Then, chemoradiotherapy was conducted, and TTFields and TMZ were performed sequentially. Notably, a long-term PFS of 34 months and a Karnofsky Performance Scale (KPS) of 90 were achieved by the patient on TTFields combined with TMZ, whose average daily usage of TTFields was higher than 90%.

Epithelioid glioblastoma (EGBM, classified as glioblastoma, wild type, grade IV according to 2021 WHO CNS5 classification of neurological malignancies) is a highly aggressive malignancy, the median progression-free survival (mPFS) of which is about 4.0 months. Although, the introduction of tumor treating fields (TTFields, possessing anti-cancer capability via anti-mitotic effects) in the maintenance of TMZ chemotherapy was demonstrated beneficial for prolonging the mPFS of GBM patients to 6.9 months in the EF-14 clinical trial, studies centering on the significance of TTFields in EGBM treating are very limited due to the rarity of EGBM. Therefore, a 28-year-old patient (male, recurrent left-sided limb twitching for 1 month and dizziness for 1 week) was chosen as a clinical trial participant. A right frontal lobe occupancy was detected based on magnetic resonance imaging (MRI), and total tumor resection was performed on the patient. Meanwhile, postoperative histopathology test, including immunohistochemical and molecular characterization, was conducted and the results revealed a BRAF V600E mutation, no codeletion of 1p and 19q, and negative MGMT promoter methylation, which confirmed EGBM. In this context, chemoradiotherapy was conducted on the patient at first, and then concurrent TTFields and TMZ was performed. Notably, a long-term PFS of 33 months and KPS score of 90 were achieved over the patient upon TTFields combined TMZ, whose average daily usage of TTFields was higher than 90%. This clinical case corroborated the importance of TTFields in EGBM treating, and the higher compliance of TTFields is more beneficial for EGBM patient without additional side effect. YD, QW contributed equally to this work. Citation Format: Yuxuan Ding, Qiang Wang, Feijiang Wang, Nan Wu, Jianrui Li, Xia He, Hao Pan, Lijun Wang. TTFields-prolonged the PFS of epithelioid glioblastoma patient: a case report [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3224.