Carfilzomib in Combination With Cyclophosphamide and Etoposide for Children

Part 1 of the study will include a dose escalation based on Dose limiting toxicities (DLTs) until the MTD or highest dose level is reached, whichever comes first. At the MTD or highest dose level (if no MTD is reached), an additional 6 patients will be enrolled to further evaluate safety of the regimen (Part 2). Part 2 of this study will enroll additional patients at the highest tolerable dose found in Part 1 in order to get more information on side effects and make sure the dose is tolerable Once an MTD is determined for Strata A or B, if the Study Principal Investigator determines that the study treatment should not be further pursued due to safety or enrollment barriers, the expansion Part or the study will be discontinued.