First immunotherapeutic CAR-T cells against the immune checkpoint protein HLA-G

J Immunother Cancer. 2021 Mar;9(3):e001998. doi: 10.1136/jitc-2020-001998.

Abstract

Background: CAR-T cells immunotherapy is a breakthrough in the treatment of hematological malignancies such as acute lymphoblastic leukemia (ALL) and B-cell malignancies. However, CAR-T therapies face major hurdles such as the lack of tumor-specific antigen (TSA), and immunosuppressive tumor microenvironment sometimes caused by the tumorous expression of immune checkpoints (ICPs) such as HLA-G. Indeed, HLA-G is remarkable because it is both a potent ICP and a TSA. HLA-G tumor expression causes immune escape by impairing innate and adaptive immune responses and by inducing a suppressive microenvironment. Yet, to date, no immunotherapy targets it.

Methods: We have developed two anti-HLA-G third-generation CARs based on new anti-HLA-G monoclonal antibodies.

Results: Anti-HLA-G CAR-T cells were specific for immunosuppressive HLA-G isoforms. HLA-G-activated CAR-T cells polarized toward T helper 1, and became cytotoxic against HLA-G+ tumor cells. In vivo, anti-HLA-G CAR-T cells were able to control and eliminate HLA-G+ tumor cells. The interaction of tumor-HLA-G with interleukin (IL)T2-expressing T cells is known to result in effector T cell functional inhibition, but anti-HLA-G CAR-T cells were insensitive to this inhibition and still exerted their function even when expressing ILT2. Lastly, we show that anti-HLA-G CAR-T cells differentiated into long-term memory effector cells, and seemed not to lose function even after repeated stimulation by HLA-G-expressing tumor cells.

Conclusion: We report for the first time that HLA-G, which is both a TSA and an ICP, constitutes a valid target for CAR-T cell therapy to specifically target and eliminate both tumor cells and HLA-G+ suppressive cells.

Keywords: adoptive; antigens; biomarkers; carbohydrate; chimeric antigen; immunotherapy; receptors; tumor; tumor escape; tumor-associated.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / genetics
  • Antibodies, Monoclonal / immunology
  • Antibodies, Monoclonal / metabolism*
  • Antigens, CD / metabolism
  • Cell Differentiation
  • Coculture Techniques
  • Cytotoxicity, Immunologic
  • HLA-G Antigens / immunology
  • HLA-G Antigens / metabolism*
  • Humans
  • Immunologic Memory
  • Immunotherapy, Adoptive*
  • K562 Cells
  • Leukemia, Erythroblastic, Acute / genetics
  • Leukemia, Erythroblastic, Acute / immunology
  • Leukemia, Erythroblastic, Acute / metabolism
  • Leukemia, Erythroblastic, Acute / therapy*
  • Leukocyte Immunoglobulin-like Receptor B1 / metabolism
  • Memory T Cells / immunology
  • Memory T Cells / metabolism
  • Memory T Cells / transplantation*
  • Mice
  • Mice, Inbred NOD
  • Mice, SCID
  • Phenotype
  • Receptors, Chimeric Antigen / genetics*
  • Receptors, Chimeric Antigen / metabolism
  • Time Factors
  • Tumor Microenvironment
  • Xenograft Model Antitumor Assays

Substances

  • Antibodies, Monoclonal
  • Antigens, CD
  • HLA-G Antigens
  • LILRB1 protein, human
  • Leukocyte Immunoglobulin-like Receptor B1
  • Receptors, Chimeric Antigen