R-PMDT Regimen in Newly Diagnosed PCNSL

Inclusion Criteria: * Newly diagnosed primary central nervous system diffuse large B-cell lymphoma * Adequate hematologic function: ANC ≥1.0×10⁹/L, PLT ≥75×10⁹/L * Adequate hepatic function: ALT/AST ≤3×ULN; total bilirubin ≤1.5×ULN * Adequate renal function: serum creatinine ≤2×ULN or CrCl ≥40 mL/min * LVEF ≥55% by echocardiography * Baseline oxygen saturation \>92% on room air * Expected survival ≥3 months Exclusion Criteria: * Prior anti-lymphoma therapy other than corticosteroids. * Uncontrolled significant cardiovascular or cerebrovascular disease. * Uncontrolled active systemic bacterial, fungal, or viral infection. * Active hepatitis B and/or active hepatitis C (HCV RNA positive). Patients with positive hepatitis B surface antigen and/or core antibody but HBV-DNA \< 1000 IU/mL may be included and should receive concurrent oral antiviral prophylaxis against HBV reactivation. * Hypersensitivity to any study drug or its components. * Other active malignancy, except for adequately controlled non-melanoma skin cancer, in situ carcinoma, or malignancy that has been in complete remission for ≥5 years. * Pregnant or lactating women. Fertile patients unwilling to use effective contraception. * Other conditions deemed inappropriate by the investigator.