ES-1 Clinical results of tumor treating fields in patients with glioblastoma in Japan, compared with global surveillance

INTRODUCTION: The tumor treatment field induces apoptosis of tumor cells by providing a low intensity, intermediate frequency, alternating current electric field via a transducer array. TTFields is based on Phase 3 EF-11 and EF-14 trials for glioblastoma in the US FDA and Japan PMDA. Therefore, I will report the statistics of TTFields use in Japan along with recent papers. METHODS: 410 patients were treated with TTFields in Japan (December 2017-), of which 17 were at Tokyo Women’s Medical University. We also referred to papers about global post-marketing surveillance and recent studies. RESULTS: Of the 410 patients, 409 (99.8%) were diagnosed with ndGBM(male: female, 66.8%: 33.2%). As of June 2020, 222 patients (54.1%) were on treatment and 188 (45.9%) were discontinued. In 17 cases at TWMU, the average age was 46.3 years. The average treatment period was 218 days, with 6 patients (35%) continuing treatment, 6 patients (35%) discontinuing due to patient wishes, and 5 patients (30%) discontinuing treatment due to recurrence. Side effects were contact dermatitis under the array in 9 patients (57%) and mild malaise in 7 patients (43%). We experienced long-term progression-free cases with TTF use of 25 months (survival 30 months after surgery) with a glioma partially resected and 21 months (survival 27 months after surgery) with a biopsied glioma. In the biopsy case, bevacizumab was used in combination during the treatment. Conclusion: In global surveillance, use for rGBM accounts for 39%, but Japan is limited to use for ndGBM due to insurance coverage. In terms of side effects, it showed a good safety profile comparable to previous trials. Long-term progression-free cases have been observed, and it is necessary to examine the characteristics of patients who respond to treatment and the effect of concomitant use with bevacizumab by prospective studies