A Study of Sotorasib in People With Brain Tumors

Inclusion Criteria: * Adult patients ≥ 18 years of age with one or more brain tumors planned for neurosurgical resection/biopsy * Patients with concomitant leptomeningeal metastasis are eligible provided they have parenchymal brain neoplastic disease requiring resection/biopsy * For all cohorts: no limit on prior CNS radiation or systemic therapyKPS ≥ 60 * Life expectancy \>12 weeks * Adequate treatment washout period from prior therapies to allow recovery from any prior treatment-related toxicities before enrollment in the judgment of the Investigator * Adequate bone marrow, renal, hepatic, and coagulation parameters (obtained ≤7 days prior to the first day of study treatment): * Absolute neutrophil count (ANC) ≥1.0 × 10\^3/μL (granulocyte-colony stimulating factor administration is not allowed within 1 week prior to C1D1) * Platelet count ≥10.0x10\^4/μL. Note: Participants requiring ongoing transfusions or growth factor support to maintain platelet count ≥10.0x10\^4/μL are not eligible. (Platelet transfusion is not allowed within 1 week prior to C1D1) * Hemoglobin ≥ 7.0 g/dL (≥ 8 g/dL in gastric cancer / gastroesophageal cancer indications). Note: Participants requiring ongoing transfusions or growth factor support to maintain hemoglobin ≥8.0 g/dL are not eligible (Red blood cell transfusion is not allowed within 1 week prior to C1D1) * Creatinine clearance ≥30 mL/min, as calculated using the Cockcroft-Gault equation * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤3 × upper limit of normal (ULN) (\<5x ULN in participants with liver metastases) * Total bilirubin ≤1.5 × ULN) if no liver metastases or \<3 × ULN in the presence of documented Gilbert's syndrome (unconjugated hyperbilirubinemia) or liver metastases at baseline Exclusion Criteria: * Known allergy or hypersensitivity to study treatment or any of the study drug excipients. For patients who are allergic to gadolinium-based agents may receive premedication as per institutional protocol or imaged without contrast at the discretion of the Principal Investigator; reactions will be managed per standard institutional protocol * Multiple primary malignancies within 3 years, with the exception of: * adequately resected non-melanoma skin cancer * carcinoma in situ of the cervix * Smoldering pre-malignant or malignant conditions with minimal concern for CNS or extracranial progression during treatment such as CLL or MGUS based on the assessment of the treating provider * curatively treated in-situ disease * other solid tumors curatively treated * for patients with metastatic breast cancer: contralateral breast cancer