Targeted antibody-mediated depletion of murine CD19 CAR T cells permanently reverses B cell aplasia
Paulina J. Paszkiewicz, Simon P. Fräßle, Shivani Srivastava, Daniel Sommermeyer, Michael Hudecek, Ingo Drexler, Michel Sadelain, Lingfeng Liu, Michael C. Jensen, Stanley R. Riddell, Dirk H. Busch
Paulina J. Paszkiewicz, Simon P. Fräßle, Shivani Srivastava, Daniel Sommermeyer, Michael Hudecek, Ingo Drexler, Michel Sadelain, Lingfeng Liu, Michael C. Jensen, Stanley R. Riddell, Dirk H. Busch
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Research Article Immunology

Targeted antibody-mediated depletion of murine CD19 CAR T cells permanently reverses B cell aplasia

Abstract

The adoptive transfer of T cells that have been genetically modified to express a CD19-specific chimeric antigen receptor (CAR) is effective for treating human B cell malignancies. However, the persistence of functional CD19 CAR T cells causes sustained depletion of endogenous CD19+ B cells and hypogammaglobulinemia. Thus, there is a need for a mechanism to ablate transferred T cells after tumor eradication is complete to allow recovery of normal B cells. Previously, we developed a truncated version of the epidermal growth factor receptor (EGFRt) that is coexpressed with the CAR on the T cell surface. Here, we show that targeting EGFRt with the IgG1 monoclonal antibody cetuximab eliminates CD19 CAR T cells both early and late after adoptive transfer in mice, resulting in complete and permanent recovery of normal functional B cells, without tumor relapse. EGFRt can be incorporated into many clinical applications to regulate the survival of gene-engineered cells. These results support the concept that EGFRt represents a promising approach to improve safety of cell-based therapies.

Authors

Paulina J. Paszkiewicz, Simon P. Fräßle, Shivani Srivastava, Daniel Sommermeyer, Michael Hudecek, Ingo Drexler, Michel Sadelain, Lingfeng Liu, Michael C. Jensen, Stanley R. Riddell, Dirk H. Busch

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Figure 1

Truncated EGFR implemented into a T2A-containing gene expression vector allows for stringent coexpression of recombinant proteins.

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Truncated EGFR implemented into a T2A-containing gene expression vector ...
(A) Schematic representation of the human EGFR (huEGFR) illustrates the structure of the WT EGFR, including 4 extracellular domains and an intracellular tyrosine kinase domain. The truncated form of the EGFR (huEGFRt) lacks domains I and II and most of the cytoplasmic region of the full-length EGFR. (B) The EGFRt can be included into gene expression vectors, e.g., encoding for a transgenic receptor or GFP, including a T2A linker for coexpression. LTR, long terminal repeats; T2A, Thosea asigna virus 2A peptide sequence. (C) Mouse splenocytes were transduced with a GFP/EGFRt gene construct. EGFR expression was detected with a biotinylated anti-EGFR mAb and streptavidin-phycoerythrin on day 4 after transduction. Cells were pregated on living lymphocytes, and numbers indicate the percentage of GFP/EGFRt+ cells. Similarly stained untransduced cells served as a negative control.