RecruitingPhase 1Biological interventionAdoptive T Cell Therapy, DC Vaccines, and Hematopoietic Stem Cells Combined With Immune checkPOINT Blockade in Patients With MedulloblastomaThis is a pilot study in a small number of children and young adults with suspected recurrent/progressive medulloblastoma (MB) looking at the feasibility and safety of adoptive cell therapy plus PD-1 blockade.