Objective: The EF-14 trial demonstrated significantly improved survival rates when adding Tumor Treating Fields (TTFields) to adjuvant chemotherapy with temozolomide (TMZ) in patients with newly diagnosed glioblastoma (GBM). In GBM patients, TTFields therapy at 200 kHz is delivered by transducer arrays that are applied to the patients' scalp. In preclinical settings, the combined treatment with TTFields and radiotherapy demonstrated synergistically enhanced efficacy in GBM cells. The presented PriCoTTF trial is currently enrolling and will evaluate the safety and efficacy of TTFields initiated prior and concomitant to combined radiochemotherapy in newly diagnosed GBM.

Methods: After complete wound-healing following surgery, TTFields therapy will be initiated in newly diagnosed GBM patients. TTFields therapy will continue throughout radiochemotherapy and adjuvant chemotherapy for a total of 9 months. Radiotherapy will be applied through the transducer arrays that mediate TTFields therapy. In total, thirty-three patients will be enrolled in two arms. In arm A, 20 adult patients will be enrolled to receive normofractionated radiotherapy whereas in Arm B, 13 elderly patients will be treated by hypofractionated radiotherapy. Chemotherapy will be applied according to institutional standard and interdisciplinary tumor conference.

Results: The primary endpoint of the trial is safety and tolerance based on the frequency of prespecified treatment-limiting toxicities. Secondary endpoints consist in particular of the frequency of adverse events, progression-free survival (PFS) and overall survival (OS). The trial is currently enrolling patients at four centers in Germany with 12 patients included at the time of abstract submission (January 2020). First practical experiences will be presented at the annual AACR meeting.

Conclusion: The combination of TTFields and radiotherapy is a promising approach to improve survival of GBM patients further. This phase I/II trial will evaluate the safety and efficacy of TTFields initiated prior and concomitant to RT in newly diagnosed GBM. Moreover, the first data obtained on efficacy (phase II) will serve as a basis for a randomized phase III trial.

Citation Format: Sied Kebir, Lazaros Lazaridis, Teresa Schmidt, Christoph Oster, Daniela Pierscianek, Nika Guberina, Christoph Kleinschnitz, Martin Proescholdt, Peter Hau, Anca-Ligia Grosu, Ulrich Sure, Björn Scheffler, Martin Stuschke, Martin Glas. PriCoTTF trial: A phase I/II trial of TTFields prior and concomitant to radiotherapy in newly diagnosed glioblastoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT106.