Glioblastoma multiforme (GBM) carries the highest mortalityrate among primary brain tumors and remains largelyunmanageable. Life expectancy following diagnosis isonly about 12 to 14 months. This has changed little fordecades despite continuing research (Fisher and Buffler,2005; Krex et al., 2007; Stupp et al., 2009; Lawrence et al.,2011; Ahmadloo et al., 2013; Alexander and Cloughesy,2017). Indeed, a recent reevaluation found that overallsurvival for GBM is woefully similar to that reported byCushing almost a century ago (Fatehi et al., 2018). Adefining characteristic of GBM is the secondary structuresof Scherer, which include diffuse parenchymal growthinvasion over the subpial surface, along white mattertracks, and through the Virchow–Robin spaces (Scherer,1940; Laws et al., 1993; Kleihues and Ohgaki, 1999;
