Durvalumab and Tremelimumab for Pediatric Malignancies

The purpose of the study is to determine the recommended dose of durvalumab and tremelimumab (immunotherapy drugs) in pediatric patients with advanced solid and hematological cancers and expand in a second phase to test the efficacy of these drugs once this dose is determined.

Inclusion Criteria: * Max Age =17 years * Solid Tumors (except primary central nervous system malignant tumors): Patients must have a histopathologic confirmation of malignancy. Patients must have progressed or are refractory to standard therapies, and for whom no standard of care treatments exist * Non-Hodgkin's Lymphoma, limited to primary mediastinal B-cell lymphoma and anaplastic large cell lymphoma. Patients must have progressed or are refractory to standard therapies, and for whom no standard of care treatments exist. * Provision of diagnostic tumor sample mandated if available * Evaluable disease * No prior exposure to immune-mediated therapy * Adequate organ and marrow function * Life expectancy of at least 3 months Exclusion Criteria: * History of allogeneic organ transplantation (exceptions may be allowed for NHL after discussion with Sponsor). History of autologous bone marrow transplant may be allowed (after discussion with Sponsor). * Active or prior documented autoimmune or inflammatory disorders (exceptions) * Uncontrolled intercurrent illness * History of primary immunodeficiency * Active infection including tuberculosis, hepatitis B, C or HIV * Any unresolved toxicity NCI CTCAE version 5.0 Grade ≥2 from previous anticancer therapy (exceptions)