RecruitingPhase 1Drug trialTargeting Pediatric Brain Tumors and Relapsed/Refractory Solid Tumors With Sodium Glucose Cotransporter 2 Inhibitors (SGLT2i)This is a pilot phase Ib study of the safety of dapagliflozin (in addition to standard of care treatment) for the treatment of pediatric patients with recurrent brain tumors and relapsed/refractory solid tumors. The primary hypothesis is that dapagliflozin is well-tolerated and safe to use in this patient population. The investigators also hypothesize that dapagliflozin will be efficacious as an adjunct to front-line chemotherapy assessed by decreased tumor markers mediated by its pleiotropic metabolic effects.