Ctni-52. Retrospective Analysis of Using Radiotherapy With Concurrent Temozolomide and Tumor Treating Fields for Chinese Patients With Newly Diagnosed Glioblastoma

Abstract

OBJECTIVES Tumor Treating Fields (TTFields) has been shown to improve the overall survival of newly diagnosed GBM (ndGBM) when combined with Temozolomide (TMZ) in the EF-14 trial. Preclinical studies suggested synergistic effects between TTFields and radiotherapy. This study is aimed to examine the safety and efficacy of combination therapy (chemoradiation concurrent with TTFields treatment) for ndGBM patients in China. METHODS From July 2020 to May 2021, 33 ndGBM patients were treated with combination therapy (radiation target volume following NCCN guidelines). Eight patients had transducer array removed during radiotherapy, others retained transducer array on scalp. All patients had assessment every two months by MRI scan. The adverse reactions and monthly compliance data for TTFields treatment were recorded. RESULTS Twenty-five patients have completed the combination therapy. Three patients retained transducer array during radiotherapy but did not limit the scalp dose (mean: 21.7Gy). As a result, Grade 2 cutaneous adverse reactions developed, and TTFields treatment was suspended. Four patients suspended TTFields treatment due to other adverse reactions. The remaining patients who had limited scalp doses (mean < 20Gy) had no suspension or delay in combination therapy due to cutaneous adverse reactions. The median time of TTFields treatment during radiotherapy is 21.24 hours/day (IQR:19.26,22.08). Two patients had progressive disease, 1 died of pulmonary infection, and 30 had stable disease. The incidence of cutaneous AE was 48.5% (16/33), Grade1: 27.2% (9/33), Grade 2: 21.2% (7/33), and Grade 3: 3% (1/33). CONCLUSIONS The combination therapy was well tolerated in Chinese patients with ndGBM. Removing transducer array during radiotherapy may increase the frequency of array replacement while reducing the patient's daily treatment time. However, retaining transducer array will increase cutaneous adverse reactions. Scalp dose limitation is required yet it allows a maximum duration of TTFields. Further follow-ups are ongoing.