Magrolimab in Children and Adults With Recurrent or Progressive Malignant Brain Tumors

Inclusion Criteria: Study Participants in Stratum A and Stratum B: * Diagnosis of recurrent or progressive malignant primary brain tumor (WHO grade III or IV), including recurrent ependymoma (WHO grade II and III). * Histologic confirmation of malignancy at original diagnosis or relapse is required for study entry. * Participants must have measureable disease. Measurable disease will be defined as lesions that can be accurately measured in two dimensions (longest diameters to be recorded) with a minimum size of no less than double the slice thickness. Previously irradiated lesions are considered non-measurable except in cases of documented progression of the lesion since the completion of radiation therapy. * Prior Therapy: * The patient must have failed at least one prior therapy, with or without surgery, prior to study registration. Prior therapies may include one of more of the following interventions: chemotherapy, immunotherapy, radiotherapy. Surgery alone does not constitute prior therapy. Patients must have fully recovered from clinically relevant acute toxic effects of all prior chemotherapy, immunotherapy, or radiotherapy prior to entering this study. * Myelosuppressive chemotherapy: Patients must have received their last dose of known myelosuppressive anticancer chemotherapy at least three weeks prior to study registration or at least six weeks prior if nitrosourea or mitomycin C. * Biologic agent: Patient must have recovered from any acute toxicity potenti…