CHI3L1 and glioblastoma: These markers include high expression of MGMT, overexpression of EGFR, presence of EGFR vIII mutation, expression of the YKL-40 gene, expression of tenascin-C, PTEN gene mutation or loss of function, loss of chromosome 10, and p53 gene mutation or loss of function.1,17,26–28 Although MGMT promoter methylation is well established as predicting tumor response to TMZ and patient outcomes, none of these markers had been definitively confirmed as a prospective biomarker in GBM treated with SOC.