Lenalidomide Maintenance Treatment in Patients With Primary Central Nervous System Lymphoma

Inclusion Criteria: 1. PCNSL patients whose achieved response (CR/PR) after first line immunochemotherapy treatment 2. histology confirmed to be PCNSL 3. ECOG \< 3 4. Hematology values must be within the following limits: Absolute neutrophil count (ANC) ≥ 1000/µl Platelets ≥75,000/µl 5. Biochemical values within the following limits: Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 x upper limit of normal (ULN) Total bilirubin ≤ 2.0 x ULN Creatinine clearance (CrCl) of greater than or equal to 30 mL/min. 6. Females of childbearing potential\* must have a negative serum or urine pregnancy test with a sensitivity of at least 50 mIU/mL within 10 - 14 days and again within24 hours prior to prescribing lenalidomide for Cycle 1 and must either commit to continued abstinence from heterosexual intercourse or begin two acceptable methods of birth control, one highly effective method and one additional effective method at the same time, at least 28 days before she starts taking lenalidomide. \*A female of childbearing potential is a sexually mature female who: 1) has not undergone a hysterectomy (the surgical removal of the uterus) or bilateral oophorectomy (the surgical removal of both ovaries) or 2) has not been naturally postmenopausal (amenorrhea following cancer therapy does not rule out childbearing potential) for at least 24 consecutive months (i.e., has had menses at any time during the preceding 24 consecutive months). 7. Men must agree to use a latex condom during sexual contact with a female of childbearing potential even if they have had a successful vasectomy. 8. Patient must understand and voluntarily sign an informed consent form, with the understanding that the patient may withdraw consent at any time without prejudice to future medical care. Exclusion Criteria: 1. Pregnant or breastfeeding females. 2. Any life-threatening illness, medical condition, or organ system dysfunction which, in the investigator's opinion, could compromise the subject's safety, interfere with the absorption or metabolism of ibrutinib capsules, or put the study outcomes at undue risk. 3. Known history of human immunodeficiency virus (HIV) or active Hepatitis C Virus or active Hepatitis B Virus infection or any uncontrolled active systemic infection requiring intravenous (IV) antibiotics. 4. Patients with extra-central nervous system lymphoma 5. Patients who were previously exposed and who developed adverse events, hypersensitivity or desquamating rash to lenalidomide 6. prior cancer history