This study involves an investigational cellular therapy called Afamitresgene Autoleucel. The overall goal of this study is to find out how safe and effective this cellular therapy is in treating people that have been diagnosed with synovial sarcoma, malignant peripheral nerve sheath tumors (MPNST), neuroblastoma or osteosarcoma that has grown or returned after being treated.

This study involves taking a study drug called venetoclax with or without standard of care chemotherapy. The overall goal of this study is to see if adding venetoclax to standard chemotherapy leads to improved survival for children and young adults with relapsed acute myeloid leukemia (AML). The study may last up to 9 years and will enroll male and female patients from the ages of 29 days to 21 years of age.

This study enrolls patients that have been diagnosed with osteosarcoma or neuroblastoma that has come back (relapsed) or has not responded to standard treatments (refractory). This study involves an investigational cellular therapy called GD2CART. The study will be testing different doses of the study drug to find the safest dose.

The purpose of the Phase 2 portion of this study is to evaluate the safety and efficacy of the study drug called palbociclib when given in combination with two other drugs (temozolomide and irinotecan) in patients with Ewing sarcoma and when given in combination with topotecan and cyclophosphamide in patients with neuroblastoma.