Pegylated Interferon ALFA-2b in Children With Juvenile Pilocytic Astrocytomas and Optic Pathway Gliomas

Inclusion Criteria: * Patients must be older than 3 years and less than or equal to 25 years of age at the time of enrollment * Patients with neurofibromatosis are eligible * Histologic confirmation is not required for this if the patient has neurofibromatosis type 1 (NF-1) with MRI findings consistent with optic pathway glioma or JPA. Any other tumors will need histological confirmation, either at the time of diagnosis or at the time of recurrence. The histological diagnosis includes World Health Organization (WHO) grade I JPA * Patients must have measurable residual disease, defined as tumor that is measurable in two or three perpendicular diameters on MRI. For a lesion to be considered measurable, it must be at least twice the slice thickness on MRI (i.e visible on more than one slice) * All patients must have a brain MRI with and without contrast (gadolinium) within 30 days prior to study enrollment. All patients with history of spinal or leptomeningeal disease and those patients with symptoms suspicious of spinal disease, must have a spine MRI with contrast (gadolinium) performed within 30 days prior to study enrollment. Lumbar puncture is necessary if there is evidence of tumor dissemination on the MRI of spine * Performance Level: Karnofsky \> or equal to 50% for patients \> 10 years of age or Lansky \> or equal to 50 for patients \< 10 years of age * Patients must have recovered (to Common Toxicity Criteria (CTC) v.5.0 ≤ Grade 1 unless indicated below) from the acute…