R-MA-PD-1 Versus R-MA in Treatment-naive Primary CNS Lymphoma

This is a prospective, open-label, multicenter, randomized controlled study in treatment-naive patients with primary central nervous system lymphoma (PCNSL, DLBCL type). Eligible participants are randomized 1:1 to the experimental arm (R-MA-PD-1: rituximab, methotrexate, cytarabine plus penpulimab) or the control arm (R-MA: rituximab, methotrexate, cytarabine). Induction is administered every 21 days for 6 cycles, followed by risk- and response-adapted consolidation (ASCT or whole-brain radiotherapy) and penpulimab maintenance. The primary objective is to compare the 2-year progression-free survival rate between the two arms.