Search

CN-121991238-A - Antibodies that bind to HLA-A02/AFP complexes and uses thereof

CN121991238ACN 121991238 ACN121991238 ACN 121991238ACN-121991238-A

Abstract

The present application provides bispecific antibodies comprising a first antigen binding fragment that binds to an HLa-a02/AFP complex and a second antigen binding fragment that binds to an activating T cell antigen, single domain antibodies that bind to an HLa-a02/AFP complex, pharmaceutical compositions comprising said bispecific antibodies or said single domain antibodies, and uses thereof.

Inventors

  • LIU ZIBIN
  • LIU ZHIGANG
  • ZHOU XIAOWEI
  • HU JUNJIE
  • HAO XIAOBO
  • LIU YULAN

Assignees

  • 北京智仁美博生物科技有限公司

Dates

Publication Date
20260508
Application Date
20241108

Claims (9)

  1. 1. A bispecific antibody comprising a first antigen-binding fragment that binds to an HLA-A02/AFP complex and a second antigen-binding fragment that binds to an activating T cell antigen; Preferably, the binding epitope of the first antigen binding fragment to the HLA-A02/AFP complex comprises one or more residues from position 158-166 (SEQ ID NO: 1) of the AFP as shown in SEQ ID NO:58, more preferably the binding epitope of the first antigen binding fragment to the HLA-A02/AFP complex comprises at least one of residues 159, 160, 162, 164, 165 of the AFP as shown in SEQ ID NO:58, and/or Preferably, the activating T cell antigen is a CD3 molecule.
  2. 2. The bispecific antibody of claim 1, wherein The first antigen binding fragment comprises HCDR1 as shown in SEQ ID NO. 18, HCDR2 as shown in SEQ ID NO. 19 and HCDR3 as shown in SEQ ID NO. 20, preferably the first antigen binding fragment is in the form of a single domain antibody, more preferably the first antigen binding fragment comprises a monovalent or multivalent single domain antibody that binds to the HLA-A02/AFP complex, and/or The second antigen-binding fragment comprises HCDR1 as shown in SEQ ID NO. 60, HCDR2 as shown in SEQ ID NO. 61, HCDR3 as shown in SEQ ID NO. 62, LCDR1 as shown in SEQ ID NO. 64, LCDR2 as shown in SEQ ID NO. 65 and LCDR3 as shown in SEQ ID NO. 66, preferably the second antigen-binding fragment is in the form of a single chain antibody (scFv) or a Fab fragment, more preferably the second antigen-binding fragment is in the form of a scFv; wherein the amino acid sequences of HCDR and LCDR are defined according to Kabat.
  3. 3. The bispecific antibody of any one of claims 1-2, wherein The first antigen binding fragment comprises an amino acid sequence as shown in SEQ ID NO 17 or 27, and/or The second antigen binding fragment comprises a heavy chain variable region with an amino acid sequence shown as SEQ ID NO. 59 and a light chain variable region with an amino acid sequence shown as SEQ ID NO. 63; Optionally, the first antigen-binding fragment comprises the amino acid sequence shown as SEQ ID NO. 17 and the second antigen-binding fragment comprises the heavy chain variable region shown as SEQ ID NO. 59 and the light chain variable region shown as SEQ ID NO. 63, or Optionally, the first antigen-binding fragment comprises the amino acid sequence shown as SEQ ID NO. 27 and the second antigen-binding fragment comprises the heavy chain variable region shown as SEQ ID NO. 59 and the light chain variable region shown as SEQ ID NO. 63.
  4. 4. The bispecific antibody of any one of claims 1-3, wherein The first antigen-binding fragment and the second antigen-binding fragment are linked by an antibody heavy chain constant region Fc fragment comprising a first Fc fragment and a second Fc fragment, preferably the antibody heavy chain constant region Fc fragment is an Fc fragment of the IgG1 subtype, more preferably the antibody heavy chain constant region Fc fragment is an Fc fragment of the IgG1m3 subtype, wherein The amino acids at positions 354 and 366 of the first Fc fragment are C and W, respectively, or the amino acids at positions 349, 366, 368 and 407 of the first Fc fragment are C, S, A and V, respectively, and the amino acids at positions 354 and 366 of the second Fc fragment are C and W, respectively, or the amino acids at positions 349, 366, 368 and 407 of the second Fc fragment are C, S, A and V, respectively, preferably the amino acids at positions 354 and 366 of the first Fc fragment are C and W, respectively, the amino acids at positions 349, 366, 368 and 407 of the second Fc fragment are C, S, A and V, respectively, and/or Amino acids 234, 235 and 331 of the first and second Fc fragments are F, E and S, respectively, and/or One of the first Fc fragment and the second Fc fragment is linked to the first antigen-binding fragment, and the other of the first Fc fragment and the second Fc fragment is linked to the second antigen-binding fragment; wherein the amino acid position of the antibody constant region is determined according to EU numbering.
  5. 5. The bispecific antibody of any one of claims 1-4, comprising a first arm that binds to an HLA-A02/AFP complex and a second arm that binds to an activated T cell antigen, wherein The first arm comprising an amino acid sequence as set forth in SEQ ID NO. 31 or 32, and The second arm comprises the amino acid sequence shown as SEQ ID NO. 33.
  6. 6. A single domain antibody that binds to the HLA-A02/AFP complex comprising HCDR1 as shown in SEQ ID NO. 18, HCDR2 as shown in SEQ ID NO 19, and HCDR3 as shown in SEQ ID NO. 20; Preferably, the single domain antibody comprises the amino acid sequence shown as SEQ ID NO. 17 or 27; wherein the amino acid sequence of HCDR is defined according to Kabat.
  7. 7. A nucleic acid molecule encoding the bispecific antibody of any one of claims 1-5 or the single domain antibody of claim 6.
  8. 8.A pharmaceutical composition comprising the bispecific antibody of any one of claims 1-5 or the single domain antibody of claim 6, and a pharmaceutically acceptable excipient, diluent or carrier.
  9. 9. Use of a bispecific antibody according to any one of claims 1-5, a single domain antibody according to claim 6, a nucleic acid molecule according to claim 7 or a pharmaceutical composition according to claim 8 for the manufacture of a medicament for the prevention or treatment of HLA-A02/AFP positive tumors, preferably selected from the group consisting of hepatocellular carcinoma, gastric cancer.

Description

Antibodies that bind to HLA-A02/AFP complexes and uses thereof Technical Field The present application relates generally to the field of genetic engineering and antibody medicine, and in particular, to single domain antibodies that bind to the HLA-A02/AFP complex, bispecific antibodies that bind to the HLA-A02/AFP complex and an activating T cell antigen, and uses thereof. Background AFP (α Fetoprotein), also known as alpha fetoprotein, is expressed during fetal development and is a major component of fetal serum. During development, the protein is produced at high levels by the yolk sac and liver and is gradually inhibited [1] after birth of the fetus. In healthy individuals, AFP is maintained at low levels throughout the life cycle, but is abnormally expressed [2、3] in hepatocellular carcinoma (HCC). The 5-year survival rate of liver cancer is only about 15% [4、5], which is one of malignant tumors with the lowest 5-year survival rate, the total global incidence is 120 tens of thousands, according to 2020 cancer data issued by world health organization, the new liver cancer cases in China exceed 41 tens of thousands and the death cases in China exceed 39 tens of thousands, respectively account for 45% and 47% worldwide, and nearly half of the new and death cases in China worldwide are possible to rise [6、7] due to the epidemic of hepatitis B and hepatitis C. Treatment generally includes surgery, chemotherapy, etc., however, this is only beneficial when performed early in the disease. Thus, new therapeutic approaches are needed. T Cell Receptor (TCR), a characteristic marker on the surface of all T cells, associates with CD3 non-covalently to form a TCR-CD3 complex. The role of the TCR is to recognize an antigen, i.e. a peptide-MHC complex (p-MHC). The intracellular proteins are degraded and processed by the proteasome, the generated peptide fragments are transported to an endoplasmic reticulum and MHC to form a complex, and finally the complex is displayed on the cell surface through the transportation of a Golgi apparatus, so that antigens which can be recognized by TCR are formed. Some of the proteins are proteins specifically expressed in tumors or diseases, and can be specific targeting antigens in treatment. Researchers have found through research that the preparation of TCR mimetic antibodies (TCRm) can effectively mimic TCRs, recognize MHC complexes of tumor specific antigens, and exert biological activity by T cells [8、9、10]. Therefore, development of TCRm ×anti-CD3 bispecific antibody drugs is another important field of drug development. AFP is degraded into small molecule polypeptides after intracellular production and is presented on the cell surface in association with MHC (major histocompatibility complex) molecules to form complexes. HLA-A02 restricted AFP epitope FMNKFIYEI [11] (SEQ ID NO: 1) provides a suitable target for novel immunotherapeutic intervention, which antigen peptide is processed naturally and eluted from the HepG2 (HLA-A 02 positive) hepatoma cell line and detected by mass spectrometry, and has generated a T cell clone [12] against AFP 158-166: FMNKFIYEI. However, TCRm antibodies recognizing this peptide have not been reported. Based on clinical requirements, the exploration and development of TCRm ×anti-CD3 bispecific antibodies targeting AFP is of great biological and clinical significance. Disclosure of Invention In a first aspect, the application provides a bispecific antibody comprising a first antigen-binding fragment that binds to an HLA-A02/AFP complex and a second antigen-binding fragment that binds to an activating T cell antigen. In some embodiments of the first aspect, the bispecific antibody is capable of mediating HLA-A02 +/AFP+ tumor cells to activate T cells, and/or the bispecific antibody is capable of mediating human Peripheral Blood Mononuclear Cells (PBMCs) to kill HLA-A02 +/AFP+ tumor cells. In some embodiments of the first aspect, the binding epitope of the first antigen binding fragment to the HLA-A02/AFP complex comprises one or more residues from position 158-166 (SEQ ID NO: 1) of the AFP as set forth in SEQ ID NO: 58. In some embodiments, the binding epitope of the first antigen binding fragment to the HLA-A02/AFP complex comprises at least one of residues 159, 160, 162, 164, 165 of AFP as set forth with reference to SEQ ID NO. 58. In some embodiments of the first aspect, the first antigen binding fragment comprises HCDR1 as set forth in SEQ ID NO. 18, HCDR2 as set forth in SEQ ID NO. 19, and HCDR3 as set forth in SEQ ID NO. 20, wherein the amino acid sequence of HCDR is defined according to Kabat. In some embodiments of the first aspect, the first antigen binding fragment is in the form of a single domain antibody. For example, the first antigen binding fragment comprises a monovalent or multivalent single domain antibody that binds to the HLA-A02/AFP complex. In some embodiments of the first aspect, the activating T cell antigen is a CD3 molecule.