There was near elimination of an <i>EGFR</i> mutated and amplified tumor clone after gross total resection, standard chemoradiation, and poliovirus therapy, followed by the emergence of a persistently <i>STAG2</i> mutated clone, with rare mutations in <i>PTPN11</i> and <i>BRAF</i>, the latter composed of a novel deleterious mutation previously not reported in pediatric glioblastoma (p.D594G). Here, PTPN11 is linked to glioblastoma.