Inclusion Criteria:

1. Patients must have histologically/cytologically confirmed primary central nervous system lymphoma (PCNSL), primary vitreoretinal lymphoma (PVRL), or CNS-only High-Grade B-cell lymphoma or CNS involvement with systemic High-Grade B-cell lymphoma (DLBCL/SCNSL).
2. All patients must have relapsed/refractory disease and have received at least one prior CNS-directed therapy.
3. Patients must be able to tolerate gadolinium-enhanced magnetic resonance imaging (MRI) scans, or contrast-enhanced computed tomography (CT).
4. Patients with parenchymal lesions must have baseline imaging (gadolinium-enhanced MRI or if contraindicated, measurable CT, of the brain) within 28 days prior to first study drug dose. For patients with leptomeningeal disease only, cerebrospinal fluid (CSF) cytology must document lymphoma cells and/or imaging findings consistent with CSF disease after informed consent and prior to first study dose (at the discretion of the Investigator).
5. Patients with parenchymal lesions must have measurable disease (disease that has at least one lesion on imaging ≥ 10 mm x 10 mm) on imaging (gadolinium-enhanced MRI or if contraindicated, measurable CT, of the brain) prior to first study dose.
6. Patients must be able to tolerate and consent for a lumbar puncture and/or have pre-existing placement of an Ommaya reservoir, unless clinically contraindicated.
7. Patients must have a performance status of 0, 1, or 2 on the Eastern Cooperative Oncology Group (ECOG) Performance Scale.
8. Demonstrate adequate bone marrow and organ function.

Exclusion Criteria:

1. Patients are concurrently using other approved or investigational antineoplastic agents.
2. Patients have an active concurrent malignancy requiring active therapy.
3. Patients are allergic to components of the study drug.
4. Patients have a known bleeding diathesis (eg, von Willebrand’s disease) or hemophilia.
5. Patients have significant abnormalities on screening electrocardiogram (ECG) and active and significant cardiovascular disease such as uncontrolled or symptomatic arrhythmias, congestive heart failure, uncontrolled hypertension, valvular disease, pericarditis, or myocardial infarction within 6 months of screening.
6. Patients with the following will be excluded:
   1. A marked baseline prolongation of QT/QTc interval (eg, repeated demonstration of a QTc interval > 480 ms [CTCAE grade 2]) using Frederica’s QT correction formula.
   2. A history of additional risk factors for Torsades de Pointes (eg, heart failure, hypokalemia, family history of long QT syndrome).
   3. The use of concomitant medications that prolong the QT/QTc interval.
7. Patients are known to have a history of active or chronic infection with hepatitis C virus (HCV), hepatitis B virus (HBV), as determined by serologic tests.
8. Known history of infection with human immunodeficiency virus (HIV).
9. Patients are known to have an uncontrolled active infection.
10. Patients have a history of stroke or intracranial hemorrhage within 6 months prior to enrollment.
11. Patients have a life-threatening illness, medical condition, or organ system dysfunction that, in the opinion of the Investigator, could compromise the subject’s safety or put the study outcomes at undue risk.
12. Women who are pregnant or nursing (lactating).