<p>Myeloid azurophil granules provide a rich source of intracellular leukemia antigens. Cathepsin G (CG) is a serine protease that has higher expression in acute myeloid leukemia (AML) blasts in comparison to normal myeloid progenitors. Based on the unique biology of HLA-A*0201 (HLA-A2), in which presentation of leader sequence (LS)-derived peptides is favored, we focused on the LS-CG-derived peptide CG1 (FLLPTGAEA). We previously detected CG1/HLA-A2 complexes on the surface of primary HLA-A2<sup>+</sup> AML blasts and cell lines, and immunity targeting CG1/HLA-A2 in leukemia patients. T cell receptor (TCR)-mimic (m) antibodies are immunotherapeutic antibodies that target peptide-HLA (pHLA) complexes. Here we report on the engineering, preclinical efficacy, and safety evaluation of a novel CG1/HLA-A2-targeting, T cell-engager, bispecific antibody (CG1/A2xCD3). CG1/A2xCD3 showed high binding affinity to CG1/HLA-A2 monomers, CD3-Fc fusion protein, and to AML and T cells, with potent killing of HLA-A2+ primary AML and cell lines in vitro and in vivo. This correlated with both tumor- and CG1/A2xCD3-dependent T cell activation and cytokine secretion. Lastly, CG1/A2xCD3 had no activity against normal bone marrow. Together, these results support the targeting of LS-derived peptides and the continued clinical development of CG1/A2xCD3 in the setting of AML.</p>

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Immunotherapy targeting a leader sequence cathepsin G-derived peptide

  • Chunhua Shi,
  • Ze Tian,
  • Jun Yan,
  • Mao Zhang,
  • Pariya Sukhumalchandra,
  • Edward Chang,
  • Guojun Yang,
  • Junping You,
  • Meng Cui,
  • Qing Shi,
  • Celine Kerros,
  • Anne Philips,
  • Na Qiao,
  • Hiroki Torikai,
  • Sathvik Patchametla,
  • Anna Sergeeva,
  • Lisa St. John,
  • Helen He,
  • Dmitri Wiederschain,
  • Benjamin H. Lee,
  • Geraldine L. C. Paulus,
  • Dongxing Zha,
  • Jeffrey Molldrem,
  • Gheath Alatrash

摘要

Myeloid azurophil granules provide a rich source of intracellular leukemia antigens. Cathepsin G (CG) is a serine protease that has higher expression in acute myeloid leukemia (AML) blasts in comparison to normal myeloid progenitors. Based on the unique biology of HLA-A*0201 (HLA-A2), in which presentation of leader sequence (LS)-derived peptides is favored, we focused on the LS-CG-derived peptide CG1 (FLLPTGAEA). We previously detected CG1/HLA-A2 complexes on the surface of primary HLA-A2+ AML blasts and cell lines, and immunity targeting CG1/HLA-A2 in leukemia patients. T cell receptor (TCR)-mimic (m) antibodies are immunotherapeutic antibodies that target peptide-HLA (pHLA) complexes. Here we report on the engineering, preclinical efficacy, and safety evaluation of a novel CG1/HLA-A2-targeting, T cell-engager, bispecific antibody (CG1/A2xCD3). CG1/A2xCD3 showed high binding affinity to CG1/HLA-A2 monomers, CD3-Fc fusion protein, and to AML and T cells, with potent killing of HLA-A2+ primary AML and cell lines in vitro and in vivo. This correlated with both tumor- and CG1/A2xCD3-dependent T cell activation and cytokine secretion. Lastly, CG1/A2xCD3 had no activity against normal bone marrow. Together, these results support the targeting of LS-derived peptides and the continued clinical development of CG1/A2xCD3 in the setting of AML.