Evidence of progressive multifocal leukoencephalopathy (PML) identified on the pretreatment magnetic resonance imaging (MRI) History of progressive multifocal leukoencephalopathy (PML) Patients with a known John Cunningham (JC) virus infection and/or progressive multifocal leukoencephalopathy (PML) are not eligible History of autoimmune disease or of confirmed progressive multifocal leukoencephalopathy History of progressive multifocal leukoencephalopathy (PML) History of progressive multifocal leukoencephalopathy (PML) Patients must not have known John Cunningham (JC) virus infection and/or progressive multifocal leukoencephalopathy (PML) History of progressive multifocal leukoencephalopathy (PML). History of progressive multifocal leukoencephalopathy (PML) Participants with known history of pancreatitis or progressive multifocal leukoencephalopathy (PML) History of progressive multifocal leukoencephalopathy (PML) Present or history of progressive multifocal leukoencephalopathy (PML) Participants with a history of progressive multifocal leukoencephalopathy History of progressive multifocal leukoencephalopathy History of or current diagnosis of progressive multifocal leukoencephalopathy (PML) Known human immunodeficiency virus (HIV) or hepatitis B positivity or prior progressive multifocal leukoencephalopathy (PML) History of progressive multifocal leukoencephalopathy (PML) History of progressive multifocal leukoencephalopathy History of progressive multifocal leukoencephalopathy (PML) History of progressive multifocal leukoencephalopathy (PML) Has active cerebral/meningeal disease, active cytomegalovirus (CMV) colitis, or signs and symptoms of progressive multifocal leukoencephalopathy (PML) or any history of PML. Participants with history of confirmed progressive multifocal leukoencephalopathy (PML) History of progressive multifocal leukoencephalopathy History of progressive multifocal leukoencephalopathy Present or history of progressive multifocal leukoencephalopathy (PML) History of progressive multifocal leukoencephalopathy Cerebral/meningeal disease, including signs and symptoms of progressive multifocal leukoencephalopathy (PML) Participants with a history of confirmed progressive multifocal leukoencephalopathy (PML) History of progressive multifocal leukoencephalopathy (PML) Known active cerebral/meningeal disease, including signs or symptoms of progressive multifocal leukoencephalopathy (PML); Participants with a history of confirmed progressive multifocal leukoencephalopathy (PML) History of progressive multifocal leukoencephalopathy (PML). In subjects with AITL, evidence of meningeal or cerebral disease or a history of progressive multifocal leukoencephalopathy History of progressive multifocal leukoencephalopathy (PML) Known active cerebral/meningeal disease, including signs or symptoms of progressive multifocal leukoencephalopathy (PML) or any history of PML Known cerebral/meningeal disease, including history of progressive multifocal leukoencephalopathy Patients with history of confirmed progressive multifocal leukoencephalopathy Known John Cunningham (JC) virus infection and/or progressive multifocal leukoencephalopathy (PML) Active cerebral/meningeal disease related to the underlying malignancy Known cerebral/meningeal disease Patients with recent cerebral hemorrhage Patients with tumors involving the cerebellum or both cerebral hemispheres Has a history of spontaneous or tumor-related cerebral hemorrhage; or has cerebral hemorrhage as determined by the screening fludeoxyglucose F-18 (FDG)-PET-computed tomography (CT) and MRI; this does not include stable post-operative blood products seen on a gradient echo MRI sequence Active cerebral/meningeal disease related to the underlying malignancy Cerebral edema, grade 3 or greater prior to surgery Known cerebral/meningeal disease Patients with cerebral metastases Documented cerebral infarction within past 12 months Patients with cerebral or systemic vasculopathy: Patients with cerebral metastases Subjects must not have clinically active cerebral metastases. Cerebral/meningeal disease related to the underlying malignancy that has not been definitively treated Active cerebral/meningeal disease related to the underlying malignancy. Documented history of a cerebral vascular event Known central nervous system (CNS) lymphomas; Active cerebral/meningeal disease related to the underlying malignancy Cerebral/meningeal disease related to the underlying malignancy Known active cerebral/meningeal lymphoma Patients with known cerebral or meningeal involvement by lymphoma are excluded Phase 2: Clinically active cerebral melanoma metastases. Subjects with up to 3 cerebral metastases, and neurological performance status of 0 may be enrolled, provided that all lesions have been adequately treated with stereotactic radiation therapy, craniotomy, or Gamma knife therapy, with no evidence of progression, and have not required steroids, for at least 2 months prior to enrollment. Clinically active cerebral metastases. Cerebral/meningeal disease related to the underlying malignancy Known cerebral or meningeal disease Known cerebral/meningeal disease No evidence of cerebral edema Cerebral/meningeal disease related to underlying malignancy Cardio or cerebral vascular event within 6 months Known intra-cerebral disease or brain mets Cerebral/meningeal disease related to the underlying malignancy, unless definitively treated. Subjects with a history of NF-1 related cerebral vascular anomaly (such as Moyamoya). Known cerebral/meningeal disease. Cerebral vascular accident Documented cerebral metastasis Prior resection of cerebral metastases Patients with recent cerebral hemorrhage Patients with recent cerebral hemorrhage