The nonsignaling extracellular spacer domain of chimeric antigen receptors is decisive for in vivo antitumor activity.

Abstract

The use of synthetic chimeric antigen receptors (CAR) to redirect T cells to recognize tumor provides a powerful new approach to cancer immunotherapy; however, the attributes of CARs that ensure optimal in vivo tumor recognition remain to be defined. Here, we analyze the influence of length and composition of IgG-derived extracellular spacer domains on the function of CARs. Our studies demonstrate that CD19-CARs with a long spacer from IgG4 hinge-CH2-CH3 are functional in vitro but lack antitumor activity in vivo due to interaction between the Fc domain within the spacer and the Fc receptor-bearing myeloid cells, leading to activation-induced T-cell death. We demonstrate that in vivo persistence and antitumor effects of CAR-T cells with a long spacer can be restored by modifying distinct regions in the CH2 domain that are essential for Fc receptor binding. Our studies demonstrate that modifications that abrogate binding to Fc receptors are crucial for CARs in which a long spacer is obligatory for tumor recognition as shown here for a ROR1-specific CAR. These results demonstrate that the length and composition of the extracellular spacer domain that lacks intrinsic signaling function can be decisive in the design of CARs for optimal in vivo activity.

• Authors: Michael Hudecek, Daniel Sommermeyer, Paula L Kosasih, Anne Silva-Benedict, Lingfeng Liu, Christoph Rader, Michael C Jensen, Stanley R Riddell
• Journal: Cancer immunology research (Cancer Immunol Res) Vol. 3 Issue 2 Pg. 125-35 (Feb 2015) ISSN: 2326-6074 [Electronic] United States
• PMID: 25212991 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: ©2014 American Association for Cancer Research.

Chemical References

• Antigens, CD19
• Immunoglobulin G
• Receptors, Antigen, T-Cell
• Recombinant Fusion Proteins

Topics

• Animals
• Antigens, CD19 (immunology)
• Burkitt Lymphoma (immunology, therapy)
• Cell Death (immunology)
• Cell Line, Tumor
• Cytotoxicity, Immunologic
• Genetic Engineering (methods)
• Genetic Vectors
• Humans
• Immunoglobulin G (immunology)
• Immunophenotyping (methods)
• Immunotherapy, Adoptive (methods)
• Lentivirus (genetics)
• Lung (immunology)
• Lymphocyte Activation (immunology)
• Mice, Inbred NOD
• Mice, SCID
• Protein Structure, Tertiary
• Receptors, Antigen, T-Cell (immunology)
• Recombinant Fusion Proteins (immunology)
• Signal Transduction (immunology)
• Structure-Activity Relationship
• T-Lymphocytes (immunology)
• Xenograft Model Antitumor Assays