GI-102 Alone or With Pembrolizumab Before Surgery for Treatment of Recurrent or Progressive IDH Wildtype Glioblastoma and IDH Mutated Grade 4 Astrocytoma

Inclusion Criteria: * Age ≥ 18 years * Disease characteristics * Tissue-confirmed progressive or recurrent World Health Organization (WHO) grade IV IDH wildtype glioblastoma (including molecular glioblastoma and gliosarcoma); and IDH mutated WHO grade 4 astrocytoma * Candidates for surgical resection * Measurable or non-measurable disease as defined by Response Assessment in Neuro-Oncology (RANO) 2.0 * Willing to undergo clinically indicated biopsy followed by resection of high-grade glioma at Mayo Clinic in Rochester, Minnesota (MN) * Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0,1, or 2 and Karnofsky performance status (KPS) ≥ 60 * NOTE: PS must be assessed (again) ≤ 7 days prior to first dose of study drug * Hemoglobin ≥ 9.0 g/dL (obtained ≤ 15 days prior to registration) * Absolute neutrophil count (ANC) ≥ 1500/mm\^3 (obtained ≤ 15 days prior to registration) * Platelet count ≥ 100,000/mm\^3 (obtained ≤ 15 days prior to registration) * Creatinine ≤ 1.5 x upper limit of normal (ULN) OR measured or calculated creatinine clearance (per institutional standard) must be ≥ 45 ml/min (obtained ≤ 15 days prior to registration) * Total bilirubin ≤ 1.5 x ULN OR direct bilirubin ≤ ULN for patients with total bilirubin levels \> 1.5 x ULN (obtained ≤ 15 days prior to registration) * Aspartate transaminase (AST) AND alanine transaminase (ALT) ≤ 2.5 x ULN (obtained ≤ 15 days prior to registration) * Amylase and lipase ≤ ULN (obtained ≤ 15 days prior to …