{
  "abstract": "Background Our long-term goal is to mitigate or eliminate an acute side effect of human CD19-specific CAR T-cell cancer immunotherapy: neurotoxicity. Although CAR T-cells specific for the B-cell-associated antigen CD19 (called CAR19 cells) have saved patients with otherwise terminal B-cell malignancies, about half experience acute neurotoxicities. These neurotoxicities range from mild to life-threatening and collectively are called immune effector cell associated neurotoxicity syndrome (ICANS); the etiology of ICANS remains obscure.Methods To understand how CAR19 therapy leads to ICANS, we developed a human CD19 transgenic (hCD19Tg) mouse model that replicates the anti-tumor efficacy and all reported toxicities – including ICANS - associated with CAR19 clinical therapy. In our model, intravenous adoptive transfer of syngeneic CAR19 T-cells specific for human CD19 into hCD19Tg mice leads to CAR19 T-cell accumulation in the brain and neuroinflammation. In the current studies, we used thin-skull surgery and two-photon microscopy to visualize EGFP+ CAR19 cells in the brains of hCD19Tg mice.Results CAR19 cells first accumulate in the subarachnoid space and then migrate down into the parenchyma through perivascular spaces. Co-injected control CAR T-cells also accumulate in the subarachnoid space but do not migrate into the parenchyma, suggesting trafficking is antigen-specific. Antigen-specific activation is also consistent with observed clusters of CAR19 cells in the brain parenchyma. To measure effects on neuronal activity, CAR19 cells were injected into hCD19Tg mice that expressed jGRECO1a, a sensitive red protein calcium indicator, in neurons. Using two-photon microscopy, we find that whisker-stimulation responses remained relatively constant but spontaneous neuronal activity increased significantly over time.Conclusions While disruption of the blood brain barrier may contribute to entry of CAR19 cells into the brain parenchyma, a major route of entry appears to be through the subarachnoid space. Once in the parenchyma, CAR19 cells likely undergo further antigen-driven activation, leading to proliferation and disruption of basal neuronal activity. Future experiments address the mechanisms by which CAR19 cells enter the brain parenchyma and alter neuronal activity. Together these findings should suggest novel strategies to blunt or prevent ICANS.",
  "authors": [
    {
      "affiliations": [
        "University of Minnesota, Minneapolis, MN, USA"
      ],
      "name": "Christopher A Pennell"
    },
    {
      "affiliations": [
        "University of Minnesota Medical School, Minneapolis, MN, USA"
      ],
      "name": "Pei-Pei Chiang"
    },
    {
      "affiliations": [
        "University of Minnesota Medical School, Minneapolis, MN, USA"
      ],
      "name": "Nina Ineza"
    },
    {
      "affiliations": [
        "University of Minnesota Medical School, Minneapolis, MN, USA"
      ],
      "name": "Bruce R Blazar"
    },
    {
      "affiliations": [
        "University of Minnesota Medical School, Minneapolis, MN, USA"
      ],
      "name": "Marija Cvetanovic"
    },
    {
      "affiliations": [
        "University of Minnesota Medical School, Minneapolis, MN, USA"
      ],
      "name": "Eric A Newman"
    }
  ],
  "title": "1050 Neurotoxicity induced by human CD19-specific CAR T-cells in a mouse model: CAR T-cells enter the brain parenchyma from the subarachnoid space and increase spontaneous neuronal signaling",
  "uid": "cdf4cd5e-5e5d-5858-ad13-3cc188f6702b"
}