P17.05.a tumor-treating fields combined with second-line chemotherapy reached progression free survival of 8.33 months in chinese recurrent glioblastoma

Abstract BACKGROUND Tumor-treating Fields (TTFields) monotherapy has been approved for recurrent glioblastoma. However, TTFields combined with second-line chemotherapy has not been well studied in China. This study aims to explore the efficacy and safety of such combination therapy for recurrent GBM. MATERIAL AND METHODS This study is a prospective, single-arm, open-label clinical trial (NCT04689087) planning to enroll 40 recurrent supratentorial GBM and use TTFields combined with physician choose second-line chemotherapy. Kaplan-Meier survival curve was used to estimate PFS, OS and survival rate. Safety of the combined treatment was assessed by AE incidence. RESULTS Thirty-four recurrent supratentorial GBM patients was enrolled from April 2019 to February 2023. The average age was 51.9 and median KPS score was 80. Seventy-seven percent (26/34) of them underwent total resection surgery and 2.9% (1/34) only experienced biopsy. Eighty-eight percent (30/34) of patients started TTFields when they were first diagnosed as recurrence, while 12% (4/34) patients started TTFields at their second time recurrence or latter, and average compliance of TTFields was 85.5%. As for molecular biomarkers, 47.1% (16/34) patients were MGMT methylated and 38.2% (13/34) were TERT mutant. Since the study initiated in 2019, one IDH-mutant patients were also enrolled. Second-line chemotherapy was combined with antiangiogenic therapy in 47.1% (16/34) patients. The median follow-up period was 8.33 months. Median PFS of these 34 recurrent GBM patients was 8.33(95% CI 4.72-11.95) months, but median OS was not reached. Six months PFS rate was 56.8% (EF-11 historical data of physicians choose chemotherapy was 15.1%) and 6 months OS rate was 74.8%. Two thirds of patients experienced grade 1 or 2 skin adverse events which can be relieved by topical corticosteroids. CONCLUSION TTFields combined with second-line chemotherapy showed favorable efficacy and safety in Chinese recurrent GBM patients.