Clinical and Genetic Landscape of Glioblastoma, <scp>IDH</scp> ‐Wildtype With <scp> <i>FGFR</i> </scp> Gene Family Alterations

Glioblastoma, isocitrate dehydrogenase wildtype (GBM, IDH-wt), is a highly aggressive brain tumor with a poor prognosis. Alterations in the fibroblast growth factor receptor (FGFR) gene family-such as FGFR::TACC fusions and FGFR1 mutations-have emerged as potential therapeutic targets; however, their clinical and genetic features in GBM, IDH-wt remain unclear. We analyzed 1076 GBM, IDH-wt cases using comprehensive genomic profiling data from the Center for Cancer Genomics and Advanced Therapeutics (C-CAT) database in Japan. FGFR alterations were detected in 8.0% of patients, including FGFR::TACC fusions (3.3%) and FGFR1 mutations (2.9%). The FGFR::TACC fusion-positive group was older at diagnosis and showed higher frequencies of TERT promoter mutation and MDM2 amplification, and lower frequencies of EGFR amplification and TP53 mutation, compared with the fusion-negative group. The FGFR1 mutation-positive group was enriched for ATRX, NF1, and PIK3CA mutations and had significantly fewer TERT promoter and PTEN mutations, compared with the mutation-negative group. No significant differences in overall survival were observed, although both groups tended to have longer median overall survival compared with their respective negative groups. This study represents the largest genomic cohort to date of FGFR alterations in GBM, IDH-wt. FGFR::TACC fusion-positive and FGFR1 mutation-positive GBMs exhibited distinct genetic profiles, highlighting the clinical relevance of molecular subclassification and providing insight for future therapeutic strategies.