Primary central nervous system lymphoma (PCNSL) is a rare extra-nodal non-Hodgkin lymphoma. The prognosis of patients has been greatly improved by the introduction of a variety of treatment regimens. High-dose methotrexate (HD-MTX) −based combination chemotherapy combined with a variety of consolidation treatments can achieve a first-line response rate of 63 % [1]. Nonetheless, up to 50–60 % of patients end up with relapsed/refractory (R/R) disease, and the prognosis of R/R PCNSL remains poor [2…