Figure 1.

Tumour evolution in BEAMing ctDNA-positive patient #1. A 35-year-old man was diagnosed with a large left temporal IDH1-R132H mutant and MGMT unmethylated glioblastoma involving the Wernicke area. Partial tumor resection was followed by concurrent RT + TMZ then followed by 10 cycles of adjuvant TMZ. Prior to the start of RT + TMZ, peripheral blood was drawn for BEAMing ctDNA analysis, detecting a mutation in IDH1-R132H (VAF 0.071%). PB draws along 6 consecutive timepoints during adjuvant TMZ was negative for IDH1-mutations coincident with a sustained partial response on MRI. After adjuvant TMZ, a wait and see period was started with tumor progression occurring in November 2020. After two cycles of TMZ the tumor progressed, and the patient was subjected to a partial resection followed by hypofractionated RT (30 Gy in 10 fractions) between March and April 2021. In September 2021 treatment with bevacizumab was started achieving a partial response after two cycles (treatment currently ongoing). BEAMing: Beads, Emulsion, Amplification and Magnetics, ctDNA: circulating tumor DNA, IHC: immunohistochemistry, LMD: leptomeningeal disease, LOD: limit of detection, MD: mutation detected, MGMT: O6-methylguanine–DNA methyltransferase, NGS: next-generation sequencing, NMD: no mutation detected, pRT: palliative radiotherapy, RT: radiotherapy, SX: surgery, TMZ: temozolomide, Unmet: unmethylated, VAF: variant allele frequency.