A 50-year-old male presented with a progressive cognitive decline, expressive aphasia, and personality changes. Brain MRI revealed a non-enhancing small region of increased T2-weighted signal in the right frontal lobe; a follow-up MRI 25 weeks later revealed an avidly enhancing mass exhibiting significant mass effect. He was eventually submitted for craniotomy and gross-total resection of the enhancing lesion. Integrated diagnosis was consistent with glioblastoma, WHO grade 4, IDH-wt, and MGMT hypermethylated. At four-weeks post-surgery, there was improvement in cognitive performance although personality changes persisted. He was treated with pLDR as part of a prospective phase II study (NCT04747145) to a total dose of 60 Gray (Gy) in 30 fractions with concurrent TMZ, which he tolerated with anticipated side effects. This was followed by adjuvant TMZ and TTF.
The patient completed a total of four cycles of TMZ and TTF before MRI of the brain, obtained at 20 weeks post-pLDR, which raised concerns for tumor progression. Increased nodular enhancement around the resection cavity ( Figure 1A ) was observed in the setting of the patient experiencing neurocognitive decline. FTB maps revealed predominantly treatment effect with 70.3% non-tumor, 22.9% tumor admixture, and 6.8% tumor tissue ( Figures 1B, D ).
At 23 weeks post-pLDR, the patient was submitted for redo-craniotomy in the absence of FTB-guidance. Near-total resection of the enhancing lesion was later confirmed by postoperative MRI ( Figure 1C ). Microscopy of the five tissue specimens revealed a combination of necrosis, hyalinized and necrotic blood vessels, chronic inflammation, foamy macrophages, mineralization, and reactive gliosis, consistent with treatment effect. Therefore, the patient resumed adjuvant treatment with TMZ and TTF. Of note, compliance with TTF averaged 90% of "ON" time throughout the treatment period. At four weeks post-redo surgery, the patient remained clinically stable.