Bruton's Tyrosine Kinase Inhibitor Ibrutinib as Maintenance Treatment in Elderly Patients With Primary CNS Lymphoma

The study will include 30 elderly patients age 60-85 with primary CNS DLBCL . Induction treatment will include Rituximab and high dose methotrexate protocol (containing at least methotrexate and one more chemotherapy agent). Patients with MRI documented response CR or PR will enter the study protocol maintenance phase which will include continous treatment with Ibrutinib 560 mg day until relapse or disease progression or occurrence of limiting toxicities