CD123-Engager T Cells as a Novel Immunotherapeutic for Acute Myeloid Leukemia

Mol Ther. 2016 Sep 29;24(9):1615-26. doi: 10.1038/mt.2016.116. Epub 2016 Jun 6.

Abstract

Immunotherapy with CD123-specific T-cell engager proteins or with T cells expressing CD123-specific chimeric antigen receptors is actively being pursued for acute myeloid leukemia. T cells secreting bispecific engager molecules (ENG-T cells) may present a promising alternative to these approaches. To evaluate therapeutic potential, we generated T cells to secrete CD123/CD3-bispecific engager molecules. CD123-ENG T cells recognized primary acute myeloid leukemia (AML) cells and cell lines in an antigen-dependent manner as judged by cytokine production and/or tumor killing, and redirected bystander T cells to AML cells. Infusion of CD123-ENG T cells resulted in regression of AML in xenograft models conferring a significant survival advantage of treated mice in comparison to mice that received control T cells. At high effector to target ratios, CD123-ENG T cells recognized normal hematopoietic stem and progenitor cells (HSPCs) with preferential recognition of HSPCs from cord blood compared to bone marrow. We therefore introduced the CD20 suicide gene that can be targeted in vivo with rituximab into CD123-ENG T cells. The expression of CD20 did not diminish the anti-AML activity of CD123-ENG T cells, but allowed for rituximab-mediated ENG-T cell elimination. Thus, ENG-T cells coexpressing CD20 suicide and CD123 engager molecules may present a promising immunotherapeutic approach for AML.

MeSH terms

  • Animals
  • Antigens, CD20 / genetics
  • Antigens, CD20 / metabolism
  • CD3 Complex / genetics
  • CD3 Complex / metabolism
  • Cell Line, Tumor
  • Cell Survival / drug effects
  • Cell Survival / genetics
  • Complement System Proteins / immunology
  • Complement System Proteins / metabolism
  • Cytokines / metabolism
  • Cytotoxicity, Immunologic
  • Disease Models, Animal
  • Genes, Transgenic, Suicide / genetics
  • Genetic Vectors / genetics
  • Hematopoietic Stem Cells / immunology
  • Hematopoietic Stem Cells / metabolism
  • Humans
  • Immunotherapy* / methods
  • Interleukin-3 Receptor alpha Subunit / genetics
  • Interleukin-3 Receptor alpha Subunit / metabolism*
  • Leukemia, Myeloid, Acute / genetics
  • Leukemia, Myeloid, Acute / immunology*
  • Leukemia, Myeloid, Acute / therapy*
  • Mice
  • Retroviridae / genetics
  • Rituximab / pharmacology
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / metabolism*
  • Transduction, Genetic
  • Xenograft Model Antitumor Assays

Substances

  • Antigens, CD20
  • CD3 Complex
  • Cytokines
  • Interleukin-3 Receptor alpha Subunit
  • Rituximab
  • Complement System Proteins