RecruitingPhase 2Drug trialOrelabrutinib,Rituximab and Methotrexate in Newly Diagnosed Primary Central Nervous System LymphomaIt is a single arm, multicenter, phase 2 study to explore the efficacy and safety study of OR-MTX chemotherapy(Orelabrutinib, Rituximab and Methotrexate)as first-line regimens in the treatment of newly diagnosed primary central nervous system lymphoma. Objective response rate is the primary endpoint.