RNA-lipid Particle (RNA-LP) Vaccines for Recurrent/Progressive Medulloblastoma (MB)

Inclusion Criteria: * Age \> 3 and \</= 39 years. * Histologically confirmed or suspected recurrent/progressive MB in first or second relapse. * Patients must have received radiation therapy as part of prior therapy. * Patient must have been enrolled on a screening consent and have had sterile collection of tumor material in a manner suitable for RNA extraction, amplification, and loading of lipid particles (LPs). * Prior Therapy: Patients must have fully recovered from all acute toxic effects of all prior anti-cancer therapy and must meet the following minimum duration from prior anti-cancer directed therapy prior to enrollment. If after the required timeframe, the numerical eligibility criteria are met, e.g., blood count criteria, the patient is considered to have recovered adequately. * XRT/External Beam Irradiation, including Protons: ≥ 90 days after local XRT; ≥ 150 days after TBI, craniospinal XRT or if radiation to ≥ 50% of the pelvis. * Other therapeutic clinical trials: ≥ 14 days after last dose of investigational agent, unless otherwise defined above. * Patients must not have received prior exposure to pp65-directed therapy or any RNA-LP therapy. * A diagnostic contrast-enhanced MRI of the brain and spine must be performed preoperatively, and diagnostic contrast-enhanced MRI of the area biopsied or resected must be performed postoperatively. Pre-op MRI must be performed within 28 days prior to study enrollment. Post-op MRI must be completed within 7 days aft…