Tumor Infiltrating Lymphocyte Therapy for Pediatric High Risk Solid Tumors

Part One of this study will determine the feasibility of creating Tumor-Infiltrating Lymphocyte (TIL) product prospectively from high-risk pediatric solid tumors. Part Two of this study will determine the safety of TIL therapy with lymphodepleting chemotherapy and post-TIL Interleukin-2 in high-risk pediatric solid tumors

INCLUSION CRITERIA Part One (Prospective biobanking study): * Patients must be ≥1 year to ≤ 21 years of age at time of enrollment to Part One. * Initial therapy patients: Patients with a histologic diagnosis of high-risk pediatric malignant solid tumors (pMST), defined as a pediatric malignant solid tumor outside of the central nervous system, newly-diagnosed or being treated with initial therapy, with expected 5-year Event-Free Survival (EFS) \