Sri Gururangan (Neuro -oncology Chair) will be responsible for providing a roadmap of the induction and salvage chemotherapy regimens to outside oncologists and acquiring documenta tion of all prescribed medications and any chemotherapy or procedure related toxicities during these periods (see attached cover letter and check sheet). Standard medication regimens may need to be adjusted due to hematologic or other toxicities and may be managed at the discretion of the treating pediatric oncologist. Focal boost radiotherapy may be delivered prior to immunotherapy if required for local control. All deviations from intended regimens during induction or salvage therapy will be documented, but not considered a protocol deviation, as is within routine standard of practice for this patient population Phase II: This study will assess the clinical impact of DC + xALT therapy in patients with first localized reMB/ PNETs. Up to 42 patients will be enrolled to treat 35 patients with reMB/PNET with DC + xALT therapy. Following surgical resection , biopsy, or cytology examination with confirmatory pathologic diagnosis, patients will be enrolled into HDC (Group A) or NMA salvage chemotherapy (Group B) based on eligibility for HDC. Patients with localized relapse and have not failed HDC+PBSCT previously will be enrolled into Group A as HDC+PBSCT is considered standard- of-care in the relapsed disease setting. Patients with Re-MATC H Protocol Page 42 of 106 Version: 20180628 disseminated disease, have p reviously failed HDC+PBSCT, or are otherwise considered poor candidates for HDC based on overall health status but otherwise meet eligibility criteria will be enrolled into Group B and will receive a salvage chemotherapy regimen followed by non -myeloablati ve cyclophosphamide/fludarabine lymphodepletive conditioning with PBSCT prior to DC + xALT therapy. For purposes of this protocol, localized relapse will be defined as recurrence in the same CNS location as the original tumor or a single location outside of the primary site. Disseminated disease will be defined as new lesions with little evidence of being contiguous with prior resection cavity, or intraventricular spread, or dissemination along any anatomically definable subcortical white matter tracts. The primary efficacy endpoint will be 12-month progression- free survival (PFS) from HDC + PBSCT or NMA salvage chemotherapy, after treatment with TTRNA -xALT and TTRNA -DCs. In Group A, t he progression- free survival experience among patients who initiated HDC after having previously received definitive radiotherapy is reported by Gururangan et al., (2008). The 12- month PFS (PFS -12) rate is 33% (95% confidence interval: 10%, 59%). The population of patients that will be treated in the current protocol is simila r to the subset of patients treated on the myeloablative regimen reported by Gururangan et al., but will also include recurrent central PNETs in addition to MB. For patients receiving NMA chemotherapy, there is no good historical benchmark. Considering t hat patients in Group B tend to have poorer prognoses than Group A, we will conservatively use the benchmark from Group A for Group B. Adoptive cellular therapy during recovery from myeloablative therapy has shown extraordinary promise in treatment of ref ractory melanoma (greater than 70% objective response rate) [3], but is a complex and labor intense individualized cancer therapy requiring a high- level of technical expertise and infrastructural support. Therefore, we would continue to refine this regimen until strong suggestion of significant improvement in treatme nt outcome were observed before proceeding to large -scale confirmatory trials. With this rationale in mind, in the current study, if the true proportion of patients with reMB/PNETs who have failed prior definitive radiotherapy experienced a PFS -12 with TTR NA-xALT and TTRNA -DCs treatment of 55% or more there would be definite interest in continuing the treatment regimen without further modification in larger confirmatory phase II or III studies. If the true PFS -12 associated with DC + xALT therapy is 33%, there would be limited interest in further investigation of this treatment approach without significant modification. Therefore, the study is designed to differentiate between a PFS -12 rate of 33% (null hypothesis) and 55% (alternative hypothesis). With 35 patients treated in the Phase II study ; this assessment has 90% power assuming a type I error rate of 0.10. There is also 97% power to differentiate between PFS -12 rates of 33% and 60%. The PFS and OS of patients with rePNETs following definitive radiotherapy does not differ significantly from reMBs following definitive RT [4,5 ] and therefore all patients will be analyzed collectively for primary and secondary endpoint evaluations in this study. Though this study is not powered for histologic tumor subgroup analyses, we will analyze PFS of patients with reMBs and rePNETs separately as a hypothesis driven investigation only to test the notion that no appreciable difference in treatment outcome for patients with reMB and other PNETs after DC + xALT therapy will be observed. Analysis of patients with reMB separately will also allow us to confirm that any comparisons with the historical control cohort made with analysis of all patients are consistent when analyzing pat ients with MB. Patients will be followed bi -monthly (+/ - one month) for the first year post -immunotherapy, then every 3 months (+/ - one month) until tumor progression and death due to any cause. As part of standard care for these patients, upon tumor prog ression, participants may undergo stereotactic biopsy or resection. As this is not a research procedure consent will be obtained separately. However, if tissue is obtained, it will be used to confirm tumor progression histologically and to assess immunologic cell infiltration and antigen expression profile in secondary recurrent tumors compared to original recurrent tumor RNA used in TTRNA -DC preparation by gene expression microarray. Children and young adults with reMB/PNETs will be identified from the patient population referred for treatment of recurrent disease. Our Center s are major referral center s for the treatment of pediatric brain tumors for the United States and abroad. Additionally, patients will be identified through referral by network res ources Re-MATC H Protocol Page 43 of 106 Version: 20180628 such as the Pediatric Brain Tumor Consortium (PBTC) (see letter of support from Dr. Larry Kun, Director PBTC) and the Pediatric Brain Tumor Foundation of the United States (PBTFUS) (see letter of support from Mike Traynor, President, PBTFUS). Group A Phase II: Patients in Group A with reMB/PNETs will start Induction therapy with attempted gross total resection for tumor debulking and to provide tumor tissue that is required for histologic diagnosis and the extraction of total tumor RNA. Approximately two weeks later, subjects will undergo a non- mobilized leukapheresis for peripheral blood mononuclear cells (PBMCs) for TTRNA -xALT and TTRNA -DC generation and then start induction chemotherapy that consist s of three to four 28 -day cycles as presented below: Leukapheresis after each induction cycle until c ollection of a minimum 2 x10 6 CD34+ cells /kg Cycle 1 & 2 Drug Dosage Route Days Given Cyclophosphamide 2g/m2/day IV over 1 hour 1, 2 Mesna 2g/m2/day IV 1, 2 Filgrastim 10mcg/kg/day SQ or IV 3 - 28* Cycle 3 & 4 Temozolomide 150mg/m2/day By mouth 1 - 5 Etoposide 30mg/m2/day By mouth 1 - 14 *administered until bone marrow recovery and leukapheresis complete Patients will undergo a non- mobilized leukapheresis prior to induction for harvest of peripheral blood mononuclear cells (PBMCs) for TTRNA -xALT and TTRNA -DC generation. The target PBMC count based on the desired dose of TTRNA -xALT and sufficient TTRNA -DCs for T cell expansion and in vivo vaccination will be collected . Afterwards, mobilized P eripheral blood stem cells ( PBSC ) will be collected afte r each induction cycle until the target CD34(+) PBSC yield needed for Consolidation ( 2x106 CD34+ cells per Kg at a minimum) is obtained. Absolute nucleated cell count collected will be adjusted as needed on a patient specific basis. Upon recovery from the 3rd or 4th cycle of induc tion chemotherapy, patients will undergo disease restaging and organ function evaluation. Patients will be replaced if they have disease progression by radiographic or histological findings or inadequate organ function. Patients without tumor progression and suitable organ function (defined below in Section 10) will be admitted to the P BMT unit to begin Consolidation as presented below : Drug Name Route Dose Schedule Instructions for administration Carboplatin IV The lesser of 500mg/m2 or dosing = AUC 7 mg/ml- min per Calvert Formula; dilute to 4 mg/ml in Normal Saline Days -8, -7,-6 IV over 4 hours through central venous catheter Re-MATC H Protocol Page 44 of 106 Version: 20180628 Etoposide IV 250mg/m2; dilute to 0.3 mg/ml in Normal Saline Days -5,-4,-3 IV over 3 hours through central venous catheter Thiotepa IV 300mg/m2; dilute to 1 mg/ml in Normal Saline Days -5,-4,-3 IV over 3 hours through central venous catheter Peripheral Blood Stem Cells IV Minimum: 2x106 CD34+ cells/kg Day 0 IV through central venous catheter per institutional guidelines TTRNA -xALT IV 3x107/kg Day 1 IV over 10-30 minutes through central venous catheter. Pre-medicate 30 -60 minutes prior to infusion with acetaminophen ( up to 10- 15 mg/kg/dose) and Benadryl ( up to 1 mg/kg) .