Single-Cell Analyses Identify Brain Mural Cells Expressing CD19 as Potential Off-Tumor Targets for CAR-T Immunotherapies

Abstract

CD19-directed immunotherapies are clinically effective for treating B-cell malignancies but also cause a high incidence of neurotoxicity. A subset of patients treated with chimeric antigen receptor (CAR) T cells or bispecific T-cell engager (BiTE) antibodies display severe neurotoxicity, including fatal cerebral edema associated with T cell infiltration into the brain. Here we report that mural cells, which surround the endothelium and are critical for blood-brain-barrier integrity, express CD19. We identify CD19 expression in brain mural cells using single-cell RNA-seq data and confirm perivascular staining at the protein level. CD19 expression in the brain begins early in development alongside the emergence of mural cell lineages and persists throughout adulthood across brain regions. Mouse mural cells demonstrate lower levels of Cd19 expression, suggesting limitations in preclinical animal models of neurotoxicity. These data suggest an on-target mechanism for neurotoxicity in CD19-directed therapies and highlight the utility of human singlecell atlases for designing immunotherapies.

Novel Oncolytic Herpes Simplex Virus 1 VC2 Promotes Long-Lasting, Systemic Anti-melanoma Tumor Immune Responses and Increased Survival in an Immunocompetent B16F10-Derived Mouse Melanoma Model

“…2A). When tumors reached greater than 1000mm 3 or mice were excessively moribund they were sacrificed. Mice for which tumors were treated with PBS all required sacrifice before 20 days post treatment (Fig.…”

“…To address the ability of VC2 treatment to induce anti-tumor on November 25, 2020 by guest http://jvi.asm.org/ Downloaded from immunity in untreated tumors we engrafted two tumors intradermally, caudal to each ear, of each mouse. Treatment with either PBS or VC2 was initiated on the left tumor when these tumors reached approximately 50mm -100mm 3 . Tumors treated with PBS exhibited similar growth rates to contralateral, untreated tumors.…”

“…Tumors were measured approximately every 2 to 3 d by using digital caliper, and tumor volumes were calculated by using the formula 1/2 (Length × Width 2 ). Tumor bearing mice were euthanized when tumors reached greater than 1000mm 3 or when mice were excessively moribund. For the abscopal experiments, 5×10 5…”

“…Approximately 8 days post engraftment, when tumors reached approximately 50 mm 3 to 100mm 3 , tumor on the left dorsal pinna was directly injected with 1x10 6 pfu of VC2 or PBS. Tumor volume was monitored every 2 days and animals were euthanized when tumors reached greater than 1000mm 3 or when mice were excessively moribund.…”

The Influence of Chimeric Antigen Receptor Structural Domains on Clinical Outcomes and Associated Toxicities

“…Similar to CRS, neurotoxicity symptoms also range in severity and type, including headaches, delirium, dysphasia, ataxia, dysmetria, decrease in level of consciousness, seizures and acute cerebral edema [ 27 , 28 , 29 ]. The incidence of neurotoxicity among CAR-T cell-treated patients is quite variable, with some neurological events occurring in combination with CRS symptoms and others at different times or in the absence of CRS, suggesting that at least in some cases the mechanism of CAR-T cell induced neurotoxicity is different to that of CRS [ 30 , 31 ]. Comprehensive and timely management plans are also in place for the treatment of neurological toxicities, often involving the administration of systemic corticosteroids including dexamethasone, which has the unfortunate consequence of interfering with CAR-T cell function [ 32 ].…”