LAUSR

Proton therapy is able to apply high radiation doses to the tumor while sparing healthy tissues by reducing integral dose. Tumor Treating Fields (TTFields) are low intensity (1–3 V/cm) and intermediate frequency (100–300 kHz) alternating electric fields that demonstrated significantly increased survival rates in combination with adjuvant temozolomide (TMZ) in patients with newly diagnosed glioblastoma (ndGBM). Here, we report on a patient with biopsied ndGBM IDH wildtype with complete radiological response. Brain MRI demonstrated an occlusive hydrocephalus and a ring enhancing lesion in the right posterior thalamus in a 42 year old male. After endoscopic ventriculostomy and stereotactic biopsy histopathological examination resulted in the diagnosis of a glioblastoma (WHO grade IV), IDH 1 wildtype (R132), IDH 2 wildtype (R172), HIST1H3B/C wildtype, TERT wildtype (C228 and C250), BRAF wildtype, and unmethylated MGMT promotor. The patient received definitive chemoradiation with TMZ to a total dose of 60Gy incl. proton boost of 5x2 GyRBE. TTFields therapy in combination with TMZ was initiated 4 weeks after completion of chemoradiation, TMZ maintenance was completed per protocol after 6 cycles. TTFields therapy was continued for more than 13 month and to-date the patient is still on therapy. Current follow up time is 20 months after initial diagnosis with the patient showing a radiological complete response. In a MRI 9 months after proton therapy, partial response and perfusion restriction in the tumor area was observed. Another MRI 3 months later showed a complete response without perfusion signal in the tumor area. Complete response was observed following combination treatment of chemoradiation with TMZ including proton boost, TMZ maintenance and TTFields in a patient with pathologically confirmed GBM IDH wildtype. To our knowledge, this is the first report on a ndGBM patient receiving proton therapy followed by TTFields therapy.