Target Validation and Efficacy of Metformin in Patients With Posterior Fossa Group A (PFA) Ependymoma

Exclusion criteria

• . Participants with a history of diabetes mellitus or those meeting criteria for pre-diabetes are excluded. Pre-diabetes is defined per American Diabetes Association criteria as any of the following: fasting plasma glucose (FPG) 100-125 mg/dL (5.6-6.9 mmol/L); 2-hour plasma glucose (OGTT) 140-199 mg/dL (7.8-11.0 mmol/L); or hemoglobin A1c (HbA1c) 5.7%-6.4% (39-47 mmol/mol).
• . Participants without any measurable disease.
• . Participants who have had chemotherapy or have received radiotherapy to the non-target lesion within 3 weeks (6 weeks for nitrosoureas or mitomycin C) prior to entering the study or those who have not recovered from adverse events due to agents administered more than 4 weeks earlier.
• . Participants must be at least 7 days since the completion of therapy with a biologic or small molecule agent. For any agent with known adverse events that can occur beyond 7 days after administration, the period prior to enrollment must be beyond the time during which adverse events are known to occur. Such participants should also be discussed with study chairs.
• . Participants with rapidly progressive symptoms that require urgent surgery that in the investigators assessment cannot be safely deferred for 6 weeks are excluded from target validation phase of the study
• . Participants who are receiving any other investigational agents.
• . Concurrent radiation therapy in any form is not permitted while on the study drug
• . History of allergic reactions attributed to compounds of similar chemical or biologic composition to metformin.