Maintenance Obinutuzumab in Treating Patients With Central Nervous System Lymphoma Who Have Achieved a Complete or Partial Response

Inclusion Criteria

• •CD20+ B-cell primary central nervous system lymphoma (PCNSL) confirmed at the time of diagnosis by histology, cytology, or immunocytochemistry from cerebrospinal fluid (CSF); diagnosis must be documented by pathology report.
• •Must have undergone first-line treatment with a high-dose methotrexate-based chemotherapy regimen with or without brain radiotherapy; high-dose methotrexate is defined as \>= 3 grams/m\^2; methotrexate dose reduction for creatinine clearance \< 100 ml/min is permitted
• •Must be within 75 days of completion of first-line treatment regimen at the time of randomization; must have achieved objective response (PR or CR/unconfirmed complete response \[CRu\]) to first-line treatment
• •Brain magnetic resonance imaging (MRI) documenting objective response must be obtained within 30 days before randomization
• •If CSF was positive for lymphoma cells at diagnosis or during first-line treatment and/or a slit lamp examination was positive at diagnosis or during first-line treatment, then the CSF and vitreal studies must have been repeated and must have indicated CR; Note: CR requires complete disappearance of all enhancing abnormalities on gadolinium-enhanced MRI; if CSF was positive for lymphoma cells at diagnosis or during first-line treatment and/or slit lamp examination was positive at diagnosis or during first-line treatment, then the CSF and vitreal studies must have been repeated and must have indicated CR; for CRu, some patients will have a small but persistent enhancing abnormality on MRI related to biopsy or focal hemorrhage; it is often difficult to ascertain whether this represents a residual nidus of tumor or scar tissue; if the abnormality does not change or slowly involutes without therapy and corticosteroids, it is reasonable to categorize as a CRu; at the time CR/CRu is determined, the patient should not have used corticosteroids for at least two weeks
• •Karnofsky performance status (KPS) \>= 60; Eastern Cooperative Oncology Group (ECOG) 0, 1, or 2
• •Signed informed consent form (ICF)
• •Ability and willingness to comply with the requirements of the study protocol
• •Total bilirubin \< 3 x the upper limit of normal (ULN), ≤ 7 days before date of randomization
• •Creatinine clearance \> 30 mL/min (calculated according to institutional standards or using Cockcroft-Gault formula), ≤ 7 days before date of randomization
• •Aspartate aminotransferase (AST) or alanine aminotransferase (ALT) ≤ 5 x ULN, ≤7 days before date of randomization
• •Platelet ≤ 75,000 cells/mm\^3, ≤ 7 days before date of randomization
• •Hemoglobin \> 9 g/dL, ≤ 7 days before date of randomization
• •Absolute neutrophil count \> 1.5 x 10\^3 cells/mm\^3, ≤ 7 days before date of randomization
• •Surgically sterile or agree to use effective contraception using an adequate measure of contraception such as oral contraceptives, intrauterine device, or barrier method of contraception in conjunction with spermicidal jelly while receiving obinutuzumab and \>= 18 months after the last dose of obinutuzumab for women, and 180 days after the last dose of obinutuzumab for men