Overview Pembrolizumab, Ibrutinib and Rituximab in PCNSL Status: Recruiting Trial end date: 2024-03-05 Target enrollment: Participant gender: Summary This research study is evaluating a combination therapy of 3 drugs as possible treatments for recurrent primary central nervous system lymphoma (PCNSL). The three drugs being used in the study are: - Pembrolizumab (MK3475) - Ibrutinib - Rituximab Phase: Phase 1/Phase 2 Details Lead Sponsor: Dana-Farber Cancer InstituteCollaborator: Merck Sharp & Dohme Corp.Treatments: PembrolizumabRituximab