Pola exhibits preclinical activity in primary and secondary CNS lymphoma xenograft models. (A) Low power magnification of a CD20 immunohistochemical stain from a coronal section of a NSG mouse brain demonstrating secondary CNS involvement of OCI-Ly10 tumor cells 19 days after IV injection. Tumor involvement is seen in both the leptomeningeal lining and the brain parenchyma. (B) Representative bioluminescent image of luciferase-expressing OCI-Ly10 tumor demonstrating secondary CNS involvement after IV injection. The arrow shows the bioluminescence signal within the brain. (C) Serial tumor burden after IV-injected OCI-Ly10 in CNS and non-CNS locations as assessed by bioluminescent imaging in NSG mice treated with pola or isotype control antibody (n = 6 mice per group). Pola was administered as a 1-time dose (1.8 mg/kg) on Day 20. (D) Survival of mice with OCI-Ly10 secondary CNSL treated with pola or isotype control (n = 6 mice per group, hazard ratio, 23.17; 95% confidence interval [CI], 3.617-148.4). (E) Serial tumor burden after stereotactical implantation of OCI-Ly10 tumor cells into the right forebrain of NSG mice as assessed by BLI in mice treated with pola or isotype control antibody (n = 4 mice per group). Mice were treated with a 1-time dose of pola (1.8 mg/kg) or isotype control antibody on Day 17. (F) Survival of mice with orthotopically implanted OCI-Ly10 primary CNSL xenografts treated with pola or isotype control antibody (n = 4 mice per group; hazard ratio, 10.12; 95% CI, 1.052-38.57). ∗P < 0.05; ∗∗∗P < 0.001. IHC, immunohistochemistry.