Sintilimab, a humanized IgG4 monoclonal antibody specific for human PD-1, was firstly approved by the National Medical Products Administration in China for treating relapsed or refractory Hodgkin lymphoma after at least two lines of systemic chemotherapy.21 Here, we present the efficacy and safety of sintilimab combined with HD-MTX, temozolomide, and rituximab (SMTR) from a single-arm phase 2 trial in patients with PCNSL as a first-line treatment. This evidence concerns the gene PDCD1 and primary central nervous system lymphoma.