Anti-ILT4 antibody and medical application thereof

Abstract

The present invention provides anti-ILT4 antibodies and medical uses thereof.

Description

Anti-ILT4 antibodies and their medical uses

[0001] This application claims priority to Chinese patent application (application number 202211093055.2, application date September 8, 2022). Technical Field

[0002] The present disclosure belongs to the field of biotechnology, and more specifically, relates to anti-ILT4 antibodies and applications thereof. Background Art

[0003] The statements herein merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0004] Immune checkpoints are a class of molecules expressed on immune cells that regulate the extent of immune responses and play a crucial role in preventing autoimmune diseases. The human immune system activates when stimulated, but does not overactivate, thanks to immune checkpoints that effectively "brake" activation and keep it within normal limits. Tumor cells overexpress certain immune checkpoint ligands to activate them, inhibiting immune cell function and allowing them to escape immune surveillance. Common targeted therapies targeting T cell immune checkpoints, such as CTLA-4 and PD-1, have been highly successful. However, due to the existence of compensatory mechanisms in other immune checkpoints, these inhibitors also suffer from low efficiency or drug resistance, necessitating the development of other promising immune checkpoint targets in clinical practice.

[0005] Immunoglobulin-like transcript 4 (ILT4, also known as LILRB2) belongs to the LILR (leukocyte immunoglobulin-like receptor) family, which consists of 11 members and can be divided into three categories based on whether their intracellular domains contain ITAMs or ITIMs. ILT4 is an inhibitory LILRB and is believed to function as an immune checkpoint. ILT4 is expressed on myeloid-derived immune cells, such as macrophages, dendritic cells, and granulocytes. Its physiological function is to bind to MHC class I molecules and regulate immune balance and homeostasis. In tumor biology, ILT4 expression is positively correlated with the number of myeloid-derived suppressor cells (MDSCs), which are one of the main causes of resistance to CTLA-4 and PD-1 antibodies. Furthermore, one of ILT4's ligands, HLA-G (non-classical MHC class I), has been reported to be widely expressed in various tumor tissues and is also considered a key mechanism of tumor cell immune escape. Targeting ILT4 can induce macrophage transformation to the pro-inflammatory M1 phenotype, enhance antigen presentation by APCs, and ultimately activate T cells. At the same time, ILT4 antibodies can also change the tumor microenvironment and reduce the inhibition of MDSC on T cells.

[0006] Currently, Merck's MK-4830 (WO2018187518A1) and Jounce's JTX-8064 (WO2019126514A2) have entered clinical phase 2 and clinical phase 1, respectively. According to clinical data released by Merck, for patients with metastatic or advanced solid tumors, the combination of MK-4830 and PD-1 antibody Keytruda can achieve an ORR of 24% (34 patients). Among them, 5 of the 11 patients whose disease progressed after PD-1 targeted therapy (45%) were relieved, indicating that ILT4 antibodies have certain potential to overcome PD-1 targeted resistance. On the other hand, the adverse reactions of MK-4830 in combination with Keytruda are similar to those of Keytruda alone, indicating that there are no obvious concerns about the safety of ILT4 antibodies.

[0007] ILT4 plays a negative immune regulatory role. Inhibitory antibodies targeting it can effectively activate immune cells and can serve as a beneficial supplement to existing immune checkpoint therapies.

[0008] Summary of the Invention

[0009] The present disclosure provides an anti-ILT4 antibody comprising a heavy chain variable region and a light chain variable region, wherein the heavy chain variable region comprises HCDR1, HCDR2, and HCDR3, and the light chain variable region comprises LCDR1, LCDR2, and LCDR3, wherein:

[0010] a. the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 of SEQ ID NO: 184 or 185, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 of SEQ ID NO: 187 or 186, respectively; or the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 of SEQ ID NO: 32, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 of SEQ ID NO: 33, respectively; or

[0011] b. the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3, respectively, of any one of SEQ ID NOs: 211, 205, 206, 207, 208, 209, or 210, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3, respectively, of any one of SEQ ID NOs: 212, 213, or 214; or the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3, respectively, of SEQ ID NO: 40, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3, respectively, of SEQ ID NO: 41; or

[0012] c. the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3, respectively, of any one of SEQ ID NOs: 181, 176, 177, 178, 179, or 180, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3, respectively, of SEQ ID NO: 183 or 182; or the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3, respectively, of SEQ ID NO: 28, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3, respectively, of SEQ ID NO: 29; or

[0013] d. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of any one of SEQ ID NOs: 193, 190, 191 or 192, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of any one of SEQ ID NOs: 194, 195 or 196; or the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of SEQ ID NO: 10, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 11; or

[0014] e. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 163, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 225 or 164; or

[0015] f. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of SEQ ID NO: 197 or 198, respectively, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 199 or 200, respectively; or the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of SEQ ID NO: 36, respectively, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 37, respectively; or

[0016] g. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of any one of SEQ ID NOs: 217, 218, 219, 220 or 221, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 222 or 223; or the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of SEQ ID NO: 42, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 43; or

[0017] h. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 34, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 35; or

[0018] i. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 18, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 19; or

[0019] j. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 20, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 21; or

[0020] k. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 24, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 25; or

[0021] 1. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 44, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 45; or

[0022] m. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 46, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 47; or

[0023] n. the heavy chain variable region HCDR1, HCDR2 and HCDR3 respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 48, and the light chain variable region LCDR1, LCDR2 and LCDR3 respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 49; or

[0024] o. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 50, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 51; or

[0025] p. the heavy chain variable region HCDR1, HCDR2 and HCDR3 respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 4, and the light chain variable region LCDR1, LCDR2 and LCDR3 respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 5; or

[0026] q. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 6, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 7; or

[0027] r. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 8, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 9; or

[0028] s. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 12, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 13; or

[0029] t. the heavy chain variable region HCDR1, HCDR2 and HCDR3 respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 14, and the light chain variable region LCDR1, LCDR2 and LCDR3 respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 15; or

[0030] u. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 16, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 17; or

[0031] v. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 22, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 23; or

[0032] w. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 26, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 27; or

[0033] x. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 30, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 31; or

[0034] y. The HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 38, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 39.

[0035] In some embodiments, the anti-ILT4 antibody as described above, wherein:

[0036] a. the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 of SEQ ID NO: 184 or 185, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 of SEQ ID NO: 187 or 186, respectively; or the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 of SEQ ID NO: 32, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 of SEQ ID NO: 33, respectively; or

[0037] b. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of any one of SEQ ID NOs: 211, 205, 206, 207, 208, 209 or 210, respectively, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of any one of SEQ ID NOs: 212, 213 or 214, respectively; or the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of SEQ ID NO: 40, respectively, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 41, respectively; or

[0038] c. the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3, respectively, of any one of SEQ ID NOs: 181, 176, 177, 178, 179, or 180, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3, respectively, of SEQ ID NO: 183 or 182; or the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3, respectively, of SEQ ID NO: 28, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3, respectively, of SEQ ID NO: 29; or

[0039] d. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of any one of SEQ ID NOs: 193, 190, 191 or 192, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of any one of SEQ ID NOs: 194, 195 or 196; or the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of SEQ ID NO: 10, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 11; or

[0040] e. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 163, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 225 or 164; or

[0041] f. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of SEQ ID NO: 197 or 198, respectively, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 199 or 200, respectively; or the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of SEQ ID NO: 36, respectively, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 37, respectively; or

[0042] g. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of any one of SEQ ID NOs: 217, 218, 219, 220 or 221, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 222 or 223; or the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of SEQ ID NO: 42, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 43; or

[0043] h. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 34, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 35; or

[0044] i. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 18, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 19; or

[0045] j. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 20, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 21; or

[0046] k. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 24, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 25; or

[0047] 1. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 44, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 45; or

[0048] m. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 46, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 47; or

[0049] n. the heavy chain variable region HCDR1, HCDR2 and HCDR3 respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 48, and the light chain variable region LCDR1, LCDR2 and LCDR3 respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 49; or

[0050] o. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 50, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 51.

[0051] In some embodiments, the anti-ILT4 antibody as described above, wherein:

[0052] a. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 184, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 187; or

[0053] b. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 211, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 212; or

[0054] c. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 181, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 183; or

[0055] d. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 193, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 194; or

[0056] e. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 163, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 225; or

[0057] f. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 197, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 199; or

[0058] g. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 217, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 222.

[0059] In some embodiments, the anti-ILT4 antibody as described above, wherein:

[0060] a. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 184, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 187; or

[0061] b. The HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 211, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 212.

[0062] In some embodiments, the anti-ILT4 antibody as described above, wherein:

[0063] p. the heavy chain variable region HCDR1, HCDR2 and HCDR3 respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 4, and the light chain variable region LCDR1, LCDR2 and LCDR3 respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 5; or

[0064] q. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 6, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 7; or

[0065] r. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 8, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 9; or

[0066] s. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 12, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 13; or

[0067] t. the heavy chain variable region HCDR1, HCDR2 and HCDR3 respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 14, and the light chain variable region LCDR1, LCDR2 and LCDR3 respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 15; or

[0068] u. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 16, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 17; or

[0069] v. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 22, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 23; or

[0070] w. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 26, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 27; or

[0071] x. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 30, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 31; or

[0072] y. The HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 38, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 39.

[0073] In some embodiments, the anti-ILT4 antibody as described in any of the above items, the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2 and LCDR3 of the light chain variable region are defined according to the same numbering convention selected from Kabat, IMGT, Chothia, AbM and Contact. In some embodiments, the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2 and LCDR3 of the light chain variable region are defined according to the Kabat numbering convention. In some embodiments, the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2 and LCDR3 of the light chain variable region are defined according to the IMGT numbering convention. In some embodiments, the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2 and LCDR3 of the light chain variable region are defined according to the Chothia numbering convention. In some embodiments, the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2 and LCDR3 of the light chain variable region are defined according to the AbM numbering convention. In some embodiments, the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2 and LCDR3 of the light chain variable region are defined according to the Contact numbering convention.

[0074] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein:

[0075] a. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 120, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 121, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0076] b. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 135, HCDR2 comprises the amino acid sequence of any one of SEQ ID NOs: 203, 136, 201, 202 or 204, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 137, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 138, LCDR2 comprises the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140; or

[0077] c. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 111, HCDR2 comprises the amino acid sequence of any one of SEQ ID NOs: 173, 112, 174 or 175, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 113, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 115, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 116; or

[0078] d. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 69, HCDR2 comprises the amino acid sequence of any one of SEQ ID NOs: 189, 70 or 188, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 71, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 72; or

[0079] e. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 165, HCDR2 comprises the amino acid sequence of SEQ ID NO: 166, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 167, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 224 or 168, LCDR2 comprises the amino acid sequence of SEQ ID NO: 169, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 170; or

[0080] f. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 125, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 126, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 127, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 128; or

[0081] g. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 141, HCDR2 comprises the amino acid sequence of SEQ ID NO: 215 or 142, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 216 or 143, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 144, LCDR2 comprises the amino acid sequence of SEQ ID NO: 145, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 146; or

[0082] h. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 99, HCDR2 comprises the amino acid sequence of SEQ ID NO: 122, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 123, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 124; or

[0083] i. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 73, HCDR2 comprises the amino acid sequence of SEQ ID NO: 87, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 88, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 89, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 90; or

[0084] j. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 91, HCDR2 comprises the amino acid sequence of SEQ ID NO: 92, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 93, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 85, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 94; or

[0085] k. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 99, HCDR2 comprises the amino acid sequence of SEQ ID NO: 100, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 101, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 102, LCDR2 comprises the amino acid sequence of SEQ ID NO: 103, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 104; or

[0086] 1. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 147, HCDR2 comprises the amino acid sequence of SEQ ID NO: 148, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 149, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 150, LCDR2 comprises the amino acid sequence of SEQ ID NO: 151, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 152; or

[0087] m. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 153, HCDR2 comprises the amino acid sequence of SEQ ID NO: 154, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 155, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 133, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0088] n. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 58, HCDR2 comprises the amino acid sequence of SEQ ID NO: 156, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 157, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 158, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 159; or

[0089] o. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 160, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 161, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 162; or

[0090] p. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 52, HCDR2 comprises the amino acid sequence of SEQ ID NO: 53, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 54, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 55, LCDR2 comprises the amino acid sequence of SEQ ID NO: 56, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 57; or

[0091] q. HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 58, HCDR2 comprises the amino acid sequence of SEQ ID NO: 59, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 60, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 63; or

[0092] r. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 64, HCDR2 comprises the amino acid sequence of SEQ ID NO: 65, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 66, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 67, LCDR2 comprises the amino acid sequence of SEQ ID NO: 56, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 68; or

[0093] s. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 73, HCDR2 comprises the amino acid sequence of SEQ ID NO: 74, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 75, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 76, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 77; or

[0094] t. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 78, HCDR2 comprises the amino acid sequence of SEQ ID NO: 79, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 80, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 81, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 82; or

[0095] u. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 52, HCDR2 comprises the amino acid sequence of SEQ ID NO: 83, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 84, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 85, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 86; or

[0096] v. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 95, HCDR2 comprises the amino acid sequence of SEQ ID NO: 96, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 97, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 85, LCDR2 comprises the amino acid sequence of SEQ ID NO: 98, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 68; or

[0097] w. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 106, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 107, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 108, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 110; or

[0098] x. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 117, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 118, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0099] y. HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 129, HCDR2 comprises the amino acid sequence of SEQ ID NO: 130, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 131, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 132, LCDR2 comprises the amino acid sequence of SEQ ID NO: 133, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 134.

[0100] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein:

[0101] a. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 120, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 121, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0102] b. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 135, HCDR2 comprises the amino acid sequence of any one of SEQ ID NOs: 203, 136, 201, 202 or 204, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 137, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 138, LCDR2 comprises the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140; or

[0103] c. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 111, HCDR2 comprises the amino acid sequence of any one of SEQ ID NOs: 173, 112, 174 or 175, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 113, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 115, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 116; or

[0104] d. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 69, HCDR2 comprises the amino acid sequence of any one of SEQ ID NOs: 189, 70 or 188, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 71, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 72; or

[0105] e. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 165, HCDR2 comprises the amino acid sequence of SEQ ID NO: 166, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 167, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 224 or 168, LCDR2 comprises the amino acid sequence of SEQ ID NO: 169, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 170; or

[0106] f. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 125, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 126, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 127, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 128; or

[0107] g. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 141, HCDR2 comprises the amino acid sequence of SEQ ID NO: 215 or 142, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 216 or 143, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 144, LCDR2 comprises the amino acid sequence of SEQ ID NO: 145, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 146; or

[0108] h. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 99, HCDR2 comprises the amino acid sequence of SEQ ID NO: 122, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 123, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 124; or

[0109] i. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 73, HCDR2 comprises the amino acid sequence of SEQ ID NO: 87, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 88, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 89, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 90; or

[0110] j. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 91, HCDR2 comprises the amino acid sequence of SEQ ID NO: 92, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 93, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 85, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 94; or

[0111] k. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 99, HCDR2 comprises the amino acid sequence of SEQ ID NO: 100, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 101, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 102, LCDR2 comprises the amino acid sequence of SEQ ID NO: 103, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 104; or

[0112] 1. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 147, HCDR2 comprises the amino acid sequence of SEQ ID NO: 148, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 149, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 150, LCDR2 comprises the amino acid sequence of SEQ ID NO: 151, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 152; or

[0113] m. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 153, HCDR2 comprises the amino acid sequence of SEQ ID NO: 154, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 155, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 133, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0114] n. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 58, HCDR2 comprises the amino acid sequence of SEQ ID NO: 156, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 157, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 158, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 159; or

[0115] o. HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 160, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 161, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 162.

[0116] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0117] a. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 120, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 121, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0118] b. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 135, HCDR2 comprises the amino acid sequence of SEQ ID NO: 203, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 137, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 138, LCDR2 comprises the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140; or

[0119] c. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 111, HCDR2 comprises the amino acid sequence of SEQ ID NO: 173, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 113, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 115, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 116; or

[0120] d. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 69, HCDR2 comprises the amino acid sequence of SEQ ID NO: 189, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 71, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 72; or

[0121] e. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 165, HCDR2 comprises the amino acid sequence of SEQ ID NO: 166, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 167, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 224, LCDR2 comprises the amino acid sequence of SEQ ID NO: 169, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 170; or

[0122] f. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 125, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 126, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 127, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 128; or

[0123] g. HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 141, HCDR2 comprises the amino acid sequence of SEQ ID NO: 215, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 216, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 144, LCDR2 comprises the amino acid sequence of SEQ ID NO: 145, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 146.

[0124] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0125] a. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 120, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 121, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0126] b. HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 135, HCDR2 comprises the amino acid sequence of SEQ ID NO: 203, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 137, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 138, LCDR2 comprises the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140.

[0127] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0128] The HCDR1 of the heavy chain variable region comprises the amino acid sequence shown in SEQ ID NO: 105, the HCDR2 comprises the amino acid sequence shown in SEQ ID NO: 120, and the HCDR3 comprises the amino acid sequence shown in SEQ ID NO: 121, and the LCDR1 of the light chain variable region comprises the amino acid sequence shown in SEQ ID NO: 114, the LCDR2 comprises the amino acid sequence shown in SEQ ID NO: 109, and the LCDR3 comprises the amino acid sequence shown in SEQ ID NO: 119.

[0129] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0130] p. HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 52, HCDR2 comprises the amino acid sequence of SEQ ID NO: 53, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 54, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 55, LCDR2 comprises the amino acid sequence of SEQ ID NO: 56, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 57; or

[0131] q. HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 58, HCDR2 comprises the amino acid sequence of SEQ ID NO: 59, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 60, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 63; or

[0132] r. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 64, HCDR2 comprises the amino acid sequence of SEQ ID NO: 65, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 66, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 67, LCDR2 comprises the amino acid sequence of SEQ ID NO: 56, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 68; or

[0133] s. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 73, HCDR2 comprises the amino acid sequence of SEQ ID NO: 74, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 75, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 76, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 77; or

[0134] t. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 78, HCDR2 comprises the amino acid sequence of SEQ ID NO: 79, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 80, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 81, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 82; or

[0135] u. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 52, HCDR2 comprises the amino acid sequence of SEQ ID NO: 83, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 84, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 85, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 86; or

[0136] v. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 95, HCDR2 comprises the amino acid sequence of SEQ ID NO: 96, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 97, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 85, LCDR2 comprises the amino acid sequence of SEQ ID NO: 98, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 68; or

[0137] w. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 106, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 107, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 108, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 110; or

[0138] x. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 117, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 118, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0139] y. HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 129, HCDR2 comprises the amino acid sequence of SEQ ID NO: 130, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 131, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 132, LCDR2 comprises the amino acid sequence of SEQ ID NO: 133, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 134.

[0140] In some embodiments, in the anti-ILT4 antibody according to any of the above items, the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2 and LCDR3 of the light chain variable region are defined according to the Kabat numbering convention.

[0141] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0142] a. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 260, HCDR2 comprises the amino acid sequence of SEQ ID NO: 261, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 262, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 263, LCDR2 comprises the amino acid sequence of SEQ ID NO: 264, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0143] b. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 267, HCDR2 comprises the amino acid sequence of SEQ ID NO: 268, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 269, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 270, LCDR2 comprises the amino acid sequence of SEQ ID NO: 271, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140;

[0144] The CDR regions are determined according to the IMGT numbering rules.

[0145] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0146] the heavy chain variable region HCDR1 comprises the amino acid sequence set forth in SEQ ID NO:260, HCDR2 comprises the amino acid sequence set forth in SEQ ID NO:261, and HCDR3 comprises the amino acid sequence set forth in SEQ ID NO:262, and the light chain variable region LCDR1 comprises the amino acid sequence set forth in SEQ ID NO:263, LCDR2 comprises the amino acid sequence set forth in SEQ ID NO:264, and LCDR3 comprises the amino acid sequence set forth in SEQ ID NO:119;

[0147] The CDR regions are determined according to the IMGT numbering rules.

[0148] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0149] a. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 265, HCDR2 comprises the amino acid sequence of SEQ ID NO: 266, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 121, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0150] b. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 272, HCDR2 comprises the amino acid sequence of SEQ ID NO: 273, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 137, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 138, LCDR2 comprises the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140;

[0151] The CDR regions are determined according to the Chothia numbering convention.

[0152] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0153] the heavy chain variable region HCDR1 comprises the amino acid sequence set forth in SEQ ID NO:265, HCDR2 comprises the amino acid sequence set forth in SEQ ID NO:266, and HCDR3 comprises the amino acid sequence set forth in SEQ ID NO:121, and the light chain variable region LCDR1 comprises the amino acid sequence set forth in SEQ ID NO:114, LCDR2 comprises the amino acid sequence set forth in SEQ ID NO:109, and LCDR3 comprises the amino acid sequence set forth in SEQ ID NO:119;

[0154] The CDR regions are determined according to the Chothia numbering convention.

[0155] In some embodiments, the anti-ILT4 antibody as described in any of the above items is a murine antibody, a chimeric antibody, a humanized antibody, or a fully human antibody. In some embodiments, the antibody is a chimeric antibody. In some embodiments, the antibody is a fully human antibody. In some embodiments, the antibody is a humanized antibody.

[0156] In some embodiments, the anti-ILT4 antibody of any of the above items comprises a framework region (FR) of a human antibody.

[0157] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0158] a. the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 184 or 185, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 187 or 186; or the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 32, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 33; or

[0159] b. the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 211, 205, 206, 207, 208, 209, or 210, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 212, 213, or 214; or the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 40, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: NO:41 has an amino acid sequence with at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98% or 99%) sequence identity; or

[0160] c. the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 181, 176, 177, 178, 179, or 180, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 183 or 182; or the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 28, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: NO:29 has an amino acid sequence with at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98% or 99%) sequence identity; or

[0161] d. the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98% or 99%) identical to SEQ ID NO: 193, 190, 191 or 192, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98% or 99%) identical to SEQ ID NO: 194, 195 or 196; or the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98% or 99%) identical to SEQ ID NO: 10, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98% or 99%) identical to SEQ ID NO: 11. NO:11 has an amino acid sequence with at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98% or 99%) sequence identity; or

[0162] e. the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 163, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 225 or 164;

[0163] f. the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 197 or 198, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 199 or 200; or the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 36, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 37; or

[0164] g. the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 217, 218, 219, 220, or 221, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 222 or 223; or the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 42, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 43. NO: 43 has an amino acid sequence with at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98% or 99%) sequence identity.

[0165] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0166] a. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 184 or 185, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 187 or 186; or

[0167] The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 32, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 33; or

[0168] b. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 211, 205, 206, 207, 208, 209 or 210, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 212, 213 or 214; or

[0169] The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 41; or

[0170] c. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 181, 176, 177, 178, 179 or 180, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 183 or 182; or

[0171] The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 28, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 29; or

[0172] d. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 193, 190, 191 or 192, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 194, 195 or 196; or

[0173] The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 10, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 11; or

[0174] e. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 163, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 225 or 164;

[0175] f. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 197 or 198, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 199 or 200; or

[0176] The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 36, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 37; or

[0177] g. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 217, 218, 219, 220 or 221, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 222 or 223; or

[0178] The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 42, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 43.

[0179] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0180] a. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 184 or 185, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 187 or 186; or

[0181] b. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 211, 205, 206, 207, 208, 209 or 210, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 212, 213 or 214; or

[0182] c. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 181, 176, 177, 178, 179 or 180, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 183 or 182; or

[0183] d. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 193, 190, 191 or 192, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 194, 195 or 196; or

[0184] e. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 163, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 225 or 164;

[0185] f. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 197 or 198, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 199 or 200; or

[0186] g. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 217, 218, 219, 220 or 221, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 222 or 223.

[0187] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0188] a. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 184, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 187; or

[0189] b. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 211, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 212; or

[0190] c. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 181, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 183; or

[0191] d. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 193, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 194; or

[0192] e. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 163, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 225;

[0193] f. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 197, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 199; or

[0194] g. The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 217, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 222.

[0195] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0196] a. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 184, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 187; or

[0197] b. The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 211, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 212.

[0198] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0199] The heavy chain variable region comprises the amino acid sequence shown in SEQ ID NO: 184, and the light chain variable region comprises the amino acid sequence shown in SEQ ID NO: 187.

[0200] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein

[0201] a. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 32, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 33; or

[0202] b. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 41; or

[0203] c. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 28, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 29; or

[0204] d. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 10, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 11; or

[0205] f. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 36, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 37; or

[0206] g. The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 42, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 43.

[0207] In some embodiments, the anti-ILT4 antibody as described in any of the above items, the heavy chain variable region has FR1, FR2, FR3 derived from IGHV4-31*01 and FR4 derived from IGHJ1*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 1E, 27S, 30T, 44K, 71R and 76S; and / or the light chain variable region has FR1, FR2, FR3 derived from IGKV1-39*01 and FR4 derived from IGKJ4*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 43S, 48V and 71Y. In some embodiments, the anti-ILT4 antibody comprises: a heavy chain variable region HCDR1 comprising the amino acid sequence of SEQ ID NO: 105, a HCDR2 comprising the amino acid sequence of SEQ ID NO: 120, and a HCDR3 comprising the amino acid sequence of SEQ ID NO: 121, and a heavy chain variable region FR comprising one or more amino acid substitutions selected from the group consisting of 1E, 27S, 30T, 44K, 71R, and 76S; and a light chain variable region LCDR1 comprising the amino acid sequence of SEQ ID NO: 114, a LCDR2 comprising the amino acid sequence of SEQ ID NO: 109, and a LCDR3 comprising the amino acid sequence of SEQ ID NO: 119, and a light chain variable region FR comprising one or more amino acid substitutions selected from the group consisting of 43S, 48V, and 71Y. In some embodiments, the variable regions and CDRs are defined according to the Kabat numbering convention.

[0208] In some embodiments, the anti-ILT4 antibody as described in any of the above items, the heavy chain variable region has FR1, FR2, FR3 derived from IGHV1-18*01 and FR4 derived from IGHJ6*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 1E, 43E, 69L, 71V, 73K, 76N and 93T; and / or the light chain variable region has FR1, FR2, FR3 derived from IGKV4-1*01 or IGKV3-11*01 and FR4 derived from IGKJ4*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 4L, 43P, 45K, 58I, 68R and 85T. In some embodiments, the anti-ILT4 antibody comprises: a heavy chain variable region HCDR1 comprising the amino acid sequence of SEQ ID NO: 135; a HCDR2 comprising the amino acid sequence of SEQ ID NO: 203, 136, 201, 202, or 204; and a HCDR3 comprising the amino acid sequence of SEQ ID NO: 137; and the heavy chain variable region FR comprises one or more amino acid substitutions selected from the group consisting of 1E, 43E, 69L, 71V, 73K, 76N, and 93T; and a light chain variable region LCDR1 comprising the amino acid sequence of SEQ ID NO: 138, LCDR2 comprising the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprising the amino acid sequence of SEQ ID NO: 140; and the light chain variable region FR comprises one or more amino acid substitutions selected from the group consisting of 4L, 43P, 45K, 58I, 68R, and 85T. In some embodiments, the variable regions and CDRs are defined according to the Kabat numbering convention.

[0209] In some embodiments, the anti-ILT4 antibody as described in any of the above items, the heavy chain variable region has FR1, FR2, FR3 derived from IGHV1-3*01 and FR4 derived from IGHJ6*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 1E, 38K, 44S, 69L, 71V, 73K and 75G; and / or the light chain variable region has FR1, FR2, FR3 derived from IGKV1-39*01 and FR4 derived from IGKJ2*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 43S, 48V and 71Y. In some embodiments, the anti-ILT4 antibody comprises: a heavy chain variable region HCDR1 comprising the amino acid sequence of SEQ ID NO: 111, a HCDR2 comprising the amino acid sequence of SEQ ID NO: 173, 112, 174, or 175, and a HCDR3 comprising the amino acid sequence of SEQ ID NO: 113, and a heavy chain variable region FR comprising one or more amino acid substitutions selected from the group consisting of 1E, 38K, 44S, 69L, 71V, 73K, and 75G; and a light chain variable region LCDR1 comprising the amino acid sequence of SEQ ID NO: 114, a LCDR2 comprising the amino acid sequence of SEQ ID NO: 115, and a LCDR3 comprising the amino acid sequence of SEQ ID NO: 116, and a light chain variable region FR comprising one or more amino acid substitutions selected from the group consisting of 43S, 48V, and 71Y. In some embodiments, the variable regions and CDRs are defined according to the Kabat numbering convention.

[0210] In some embodiments, the anti-ILT4 antibody as described in any of the above items, the heavy chain variable region has FR1, FR2, FR3 derived from IGHV3-21*01 and FR4 derived from IGHJ1*01, and is unsubstituted or has a 49A substitution; and / or the light chain variable region has FR1, FR2, FR3 derived from IGKV1-33*01 and FR4 derived from IGKJ4*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 39R, 42Q, 43S and 85V. In some embodiments, the anti-ILT4 antibody comprises: HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 69, HCDR2 comprises the amino acid sequence of SEQ ID NO: 189, 70, or 188, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 71, and the FR of the heavy chain variable region comprises a 49A substitution; and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 72, and the FR of the light chain variable region comprises one or more amino acid substitutions selected from the group consisting of 39R, 42Q, 43S, and 85V. In some embodiments, the variable regions and CDRs are defined according to the Kabat numbering convention.

[0211] In some embodiments, the anti-ILT4 antibody as described in any of the above items, the heavy chain variable region has FR1, FR2, FR3 derived from IGHV4-31*02 and FR4 derived from IGHJ6*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 1E, 27Y, 30T, 42E, 44K and 71R; and / or the light chain variable region has FR1, FR2, FR3 derived from IGKV1-39*01 and FR4 derived from IGKJ4*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 43S, 48L and 71Y. In some embodiments, the anti-ILT4 antibody comprises: a heavy chain variable region HCDR1 comprising the amino acid sequence of SEQ ID NO: 105, a HCDR2 comprising the amino acid sequence of SEQ ID NO: 125, and a HCDR3 comprising the amino acid sequence of SEQ ID NO: 126, and a heavy chain variable region FR comprising one or more amino acid substitutions selected from the group consisting of 1E, 27Y, 30T, 42E, 44K, and 71R; and a light chain variable region LCDR1 comprising the amino acid sequence of SEQ ID NO: 127, a LCDR2 comprising the amino acid sequence of SEQ ID NO: 109, and a LCDR3 comprising the amino acid sequence of SEQ ID NO: 128, and a light chain variable region FR comprising one or more amino acid substitutions selected from the group consisting of 43S, 48L, and 71Y. In some embodiments, the variable regions and CDRs are defined according to the Kabat numbering convention.

[0212] In some embodiments, the anti-ILT4 antibody as described in any of the above items, the heavy chain variable region has FR1, FR2, FR3 derived from IGHV1-18*01 and FR4 derived from IGHJ6*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 1E, 2I, 44A, 46K and 76T; and / or the light chain variable region has FR1, FR2, FR3 derived from IGKV4-1*01 or IGKV2-28*01 and FR4 derived from IGKJ4*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 43S and 48L. In some embodiments, the anti-ILT4 antibody comprises: a heavy chain variable region HCDR1 comprising the amino acid sequence of SEQ ID NO: 141, a HCDR2 comprising the amino acid sequence of SEQ ID NO: 215 or 142, and a HCDR3 comprising the amino acid sequence of SEQ ID NO: 216 or 143, and a heavy chain variable region FR comprising one or more amino acid substitutions selected from the group consisting of 1E, 2I, 44A, 46K, and 76T; and a light chain variable region LCDR1 comprising the amino acid sequence of SEQ ID NO: 144, a LCDR2 comprising the amino acid sequence of SEQ ID NO: 145, and a LCDR3 comprising the amino acid sequence of SEQ ID NO: 146, and a light chain variable region FR comprising one or more amino acid substitutions selected from the group consisting of 43S and 48L. In some embodiments, the variable regions and CDRs are defined according to the Kabat numbering convention.

[0213] In some embodiments, the anti-ILT4 antibody as described in any of the above items, wherein the anti-ILT4 antibody is an antibody fragment; in some embodiments, the antibody fragment is selected from Fab, Fab′, F(ab′)2, Fd, Fv, scFv, dsFv or dAb.

[0214] In some embodiments, the anti-ILT4 antibody of any of the above items comprises a heavy chain constant region and a light chain constant region. In some embodiments, the heavy chain constant region is a human IgG1 or IgG4 heavy chain constant region. In some embodiments, the heavy chain constant region comprises 234A and 235A mutations, where the mutations are numbered according to the EU index. In some embodiments, the light chain constant region is a human kappa light chain constant region. In some embodiments, the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 240 or 171, and the light chain constant region comprises the amino acid sequence of SEQ ID NO: 172. In some embodiments, the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 240, and the light chain constant region comprises the amino acid sequence of SEQ ID NO: 172.

[0215] In some embodiments, the anti-ILT4 antibody as described in any of the above items comprises a heavy chain and a light chain, wherein,

[0216] a. the heavy chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 228, and the light chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 229; or

[0217] b. the heavy chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 234, and the light chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 235; or

[0218] c. the heavy chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 226, and the light chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 227; or

[0219] d. the heavy chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 230, and the light chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 231; or

[0220] e. the heavy chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 238, and the light chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 239; or

[0221] f. the heavy chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 232, and the light chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 233; or

[0222] g. the heavy chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 236, and the light chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 237.

[0223] In some embodiments, the anti-ILT4 antibody as described in any of the above items comprises a heavy chain and a light chain, wherein,

[0224] a. the heavy chain comprises the amino acid sequence of SEQ ID NO: 228, and the light chain comprises the amino acid sequence of SEQ ID NO: 229;

[0225] b. the heavy chain comprises the amino acid sequence of SEQ ID NO: 234, and the light chain comprises the amino acid sequence of SEQ ID NO: 235;

[0226] c. the heavy chain comprises the amino acid sequence of SEQ ID NO: 226, and the light chain comprises the amino acid sequence of SEQ ID NO: 227;

[0227] d. the heavy chain comprises the amino acid sequence of SEQ ID NO: 230, and the light chain comprises the amino acid sequence of SEQ ID NO: 231;

[0228] e. the heavy chain comprises the amino acid sequence of SEQ ID NO: 238, and the light chain comprises the amino acid sequence of SEQ ID NO: 239;

[0229] f. the heavy chain comprises the amino acid sequence of SEQ ID NO: 232, and the light chain comprises the amino acid sequence of SEQ ID NO: 233;

[0230] g. The heavy chain comprises the amino acid sequence of SEQ ID NO: 236, and the light chain comprises the amino acid sequence of SEQ ID NO: 237.

[0231] In some embodiments, the anti-ILT4 antibody as described in any of the above items comprises a heavy chain and a light chain, wherein,

[0232] a. the heavy chain comprises the amino acid sequence of SEQ ID NO: 228, and the light chain comprises the amino acid sequence of SEQ ID NO: 229;

[0233] b. The heavy chain comprises the amino acid sequence of SEQ ID NO: 234, and the light chain comprises the amino acid sequence of SEQ ID NO: 235.

[0234] In some embodiments, the anti-ILT4 antibody as described in any of the above items comprises a heavy chain and a light chain, wherein,

[0235] The heavy chain comprises the amino acid sequence shown in SEQ ID NO: 228, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 229.

[0236] In some embodiments, the present disclosure also provides an isolated anti-ILT4 antibody that competes with any of the above anti-ILT4 antibodies for binding to human ILT4 or an epitope thereof.

[0237] In some embodiments, the anti-ILT4 antibodies provided herein specifically bind to human ILT4 and do not bind to other LILR family members ILT2, ILT3, LILRB5, LILRA1, LILRA2, LILRA3, LILRA4, LILRA5 and / or LILRA6.

[0238] In some embodiments, the anti-ILT4 antibodies isolated in the present disclosure have a higher binding ability to the ILT4 protein than the control antibody. Specifically, the anti-ILT4 antibodies isolated in the present disclosure have a binding ability of less than 1×10 -8 M (e.g. less than 8×10 -9 M, less than 5×10 -9 M, less than 2×10 -9 M, less than 1×10 -9 M, less than 8×10 -10 M, less than 5×10 -10 M, less than 2×10 -10 M, less than 1×10 -10 M, less than 8×10 -11 M, less than 5×10 -11 M) KD values ​​for binding to human ILT4, as measured by Biacore.

[0239] In some embodiments, the humanized anti-ILT4 antibodies provided herein can effectively relieve the inhibitory effect of ILT4 and promote 3A9 cells to secrete higher levels of mIL-2.

[0240] In some embodiments, the humanized anti-ILT4 antibodies provided herein can effectively promote the transformation of macrophages to the M1 phenotype and secrete high levels of the pro-inflammatory cytokine TNF-α.

[0241] In some embodiments, the humanized anti-ILT4 antibodies (eg, huP2-G9) provided herein can induce dendritic cells to secrete higher levels of proinflammatory cytokines or chemokines in the presence of IL-10 in an immunosuppressive environment.

[0242] In some embodiments, the humanized anti-ILT4 antibodies provided herein can effectively block the binding of ILT4 to HLA-G.

[0243] In some embodiments, the humanized anti-ILT4 antibodies provided herein can effectively block the binding of ILT4 to HLA-G, and the blocking activity is stronger than that of the control antibodies MK and JTX.

[0244] In another aspect, the present disclosure provides a pharmaceutical composition comprising an anti-ILT4 antibody as described in any of the above items, and one or more pharmaceutically acceptable carriers, diluents, or excipients. In some embodiments, the pharmaceutical composition further comprises at least one second therapeutic agent. In some embodiments, the second therapeutic agent is an anti-PD-1 antibody.

[0245] In another aspect, the present disclosure provides an isolated nucleic acid encoding the anti-ILT4 antibody as described in any one of the above items.

[0246] In another aspect, the present disclosure provides a vector comprising the aforementioned nucleic acid molecule.

[0247] In another aspect, the present disclosure provides a host cell comprising the isolated nucleic acid as described in any one of the above items.

[0248] In another aspect, the present disclosure provides a method of blocking the binding of ILT4 to HLA-G in a human subject in need thereof, comprising administering to the human subject an effective amount of the anti-ILT4 antibody according to any one of the above items.

[0249] In another aspect, the present disclosure provides a method for detecting an ILT4 peptide or a fragment thereof in a sample, the method comprising contacting the sample with an anti-ILT4 antibody as described in any one of the above items, and detecting the presence of a complex between the anti-ILT4 antibody and the ILT4 peptide or a fragment thereof; wherein detection of the complex indicates the presence of the ILT4 peptide or a fragment thereof.

[0250] In another aspect, the present disclosure provides a method for treating a disease, comprising the step of administering to a subject the anti-ILT4 antibody or pharmaceutical composition described in any one of the above items.

[0251] In another aspect, the present disclosure provides use of the anti-ILT4 antibody or pharmaceutical composition as described in any one of the above items in the preparation of a medicament for treating a disease.

[0252] In another aspect, the present disclosure provides an anti-ILT4 antibody or pharmaceutical composition as described above for use as a medicament. In some embodiments, the medicament is used to treat a disease.

[0253] In some embodiments, the disease as described in any one of the above is a tumor. In some embodiments, the disease is selected from astrocytoma (e.g., anaplastic astrocytoma), glioblastoma, bladder cancer, bone cancer, brain cancer, breast cancer (e.g., breast cancer characterized by BRCA1 and / or BRCA2 mutations), carcinoid, cervical cancer, choroid plexus papilloma, colorectal cancer (e.g., colon cancer and rectal cancer), fallopian tube cancer, ependymoma, gallbladder cancer, gastric cancer, head and neck cancer, idiopathic myelofibrosis, kidney cancer or renal cell carcinoma (e.g., renal rhabdoid tumor and Wilms' tumor), renal pelvis tumor, leukemia, liver cancer (e.g., hepatocellular carcinoma), esophageal cancer (also known as "esophageal cancer", e.g., esophageal squamous cell carcinoma), lung cancer (e.g., non-small cell lung cancer and small cell lung cancer), lymphoma. In some embodiments, the disease is selected from the group consisting of ovarian cancer, lung cancer, esophageal squamous cell carcinoma, colorectal cancer, renal cell carcinoma, and melanoma.

[0254] In some embodiments, the method for treating a disease as described above further comprises administering a second therapeutic agent. In some embodiments, the second therapeutic agent comprises an immune checkpoint inhibitor. In some embodiments, the second therapeutic agent is an anti-PD-1 antibody.

[0255] In some embodiments, the method for treating a disease as described above, wherein the anti-PD-1 antibody comprises a heavy chain variable region PD-1-VH and a light chain variable region PD-1-VL, wherein:

[0256] The PD-1-VH has: PD-1-HCDR1 comprising the amino acid sequence of SEQ ID NO: 250, PD-1-HCDR2 comprising the amino acid sequence of SEQ ID NO: 251, and PD-1-HCDR3 comprising the amino acid sequence of SEQ ID NO: 252; and the PD-1-VL has: PD-1-LCDR1 comprising the amino acid sequence of SEQ ID NO: 253, PD-1-LCDR2 comprising the amino acid sequence of SEQ ID NO: 254, and PD-1-LCDR3 comprising the amino acid sequence of SEQ ID NO: 255.

[0257] In some embodiments, the method for treating a disease as described above, wherein the anti-PD-1 antibody comprises a heavy chain variable region PD-1-VH and a light chain variable region PD-1-VL, wherein:

[0258] The PD-1-VH comprises the amino acid sequence of SEQ ID NO: 256, and the PD-1-VL comprises the amino acid sequence of SEQ ID NO: 257.

[0259] In some embodiments, the method for treating a disease as described above, wherein the anti-PD-1 antibody comprises a heavy chain and a light chain, wherein:

[0260] The heavy chain comprises the amino acid sequence of SEQ ID NO: 248, and the light chain comprises the amino acid sequence of SEQ ID NO: 249.

[0261] In another aspect, use of the combination of the anti-ILT4 antibody and the anti-PD-1 antibody as described in any one of the above items in the preparation of a medicament for treating a disease.

[0262] In some embodiments, the drug as described above is used to treat a disease; preferably, the disease is a tumor; more preferably, the disease is selected from astrocytoma (e.g., anaplastic astrocytoma), glioblastoma, bladder cancer, bone cancer, brain cancer, breast cancer (e.g., breast cancer characterized by BRCA1 and / or BRCA2 mutations), carcinoid, cervical cancer, choroid plexus papilloma, colorectal cancer (e.g., colon cancer and rectal cancer), fallopian tube cancer, ependymoma, gallbladder cancer, gastric cancer, head and neck cancer, idiopathic myelofibrosis, kidney cancer or renal cell carcinoma (e.g., renal rhabdoid tumor and Wilms' tumor), renal pelvis tumor, leukemia, liver cancer (e.g., hepatocellular carcinoma), esophageal cancer (also known as "esophageal cancer", e.g., esophageal squamous cell carcinoma), lung cancer (e.g., non-esophageal cancer), In some embodiments, the drug is used to treat a disease selected from the group consisting of ovarian cancer, lung cancer, esophageal squamous cell carcinoma, colorectal cancer, renal cell carcinoma, and melanoma.

[0263] In some embodiments, the combination of the anti-ILT4 antibody and the anti-PD-1 antibody as described above is used to prepare a medicament for treating a disease, wherein the anti-ILT4 antibody and the anti-PD-1 antibody are in the same or different containers.

[0264] In some embodiments, the combination of an anti-ILT4 antibody and an anti-PD-1 antibody as described above is used to prepare a medicament for treating a disease, wherein the anti-PD-1 antibody comprises a heavy chain variable region PD-1-VH and a light chain variable region PD-1-VL, wherein:

[0265] The PD-1-VH has: PD-1-HCDR1 comprising the amino acid sequence of SEQ ID NO: 250, PD-1-HCDR2 comprising the amino acid sequence of SEQ ID NO: 251, and PD-1-HCDR3 comprising the amino acid sequence of SEQ ID NO: 252; and the PD-1-VL has: PD-1-LCDR1 comprising the amino acid sequence of SEQ ID NO: 253, PD-1-LCDR2 comprising the amino acid sequence of SEQ ID NO: 254, and PD-1-LCDR3 comprising the amino acid sequence of SEQ ID NO: 255.

[0266] In some embodiments, the combination of an anti-ILT4 antibody and an anti-PD-1 antibody as described above is used to prepare a medicament for treating a disease, wherein the anti-PD-1 antibody comprises a heavy chain variable region PD-1-VH and a light chain variable region PD-1-VL, wherein:

[0267] The PD-1-VH comprises the amino acid sequence of SEQ ID NO: 256, and the PD-1-VL comprises the amino acid sequence of SEQ ID NO: 257.

[0268] In some embodiments, the combination of the aforementioned anti-ILT4 antibody and anti-PD-1 antibody is used to prepare a medicament for treating a disease, wherein the anti-PD-1 antibody comprises a heavy chain and a light chain, wherein:

[0269] The heavy chain comprises the amino acid sequence of SEQ ID NO: 248, and the light chain comprises the amino acid sequence of SEQ ID NO: 249.

[0270] On the other hand, the combination of an anti-ILT4 antibody and an anti-PD-1 antibody as described in any of the above items is used to treat a disease; preferably, the disease is a tumor; more preferably, the disease is selected from astrocytoma (e.g., anaplastic astrocytoma), glioblastoma, bladder cancer, bone cancer, brain cancer, breast cancer (e.g., breast cancer characterized by BRCA1 and / or BRCA2 mutations), carcinoid, cervical cancer, choroid plexus papilloma, colorectal cancer (e.g., colon cancer and rectal cancer), fallopian tube cancer, ependymoma, gallbladder cancer, gastric cancer, head and neck cancer, idiopathic myelofibrosis, kidney cancer or renal cell carcinoma (e.g., renal rhabdoid tumor and Wilms' tumor), renal pelvis tumor, leukemia, liver cancer (e.g., hepatocellular carcinoma), esophageal cancer (also known as "esophageal cancer", e.g., esophageal squamous cell carcinoma), Cancer, including but not limited to: ovarian cancer, lung cancer (e.g., non-small cell lung cancer and small cell lung cancer), lymphoma, medulloblastoma, melanoma, meningioma, Merkel cell carcinoma, mesothelioma, multiple myeloma, neuroblastoma, oligodendroglioma, ovarian cancer, peritoneal tumors, pancreatic cancer, polycythemia vera, primary neuroectodermal tumors, prostate cancer, retinoblastoma, salivary gland cancer, sarcomas (e.g., chondrosarcoma, Ewing's sarcoma, osteosarcoma, rhabdomyosarcoma, synovial sarcoma, and soft tissue sarcomas), small intestine cancer, colorectal cancer, squamous cell carcinoma (e.g., cutaneous squamous cell carcinoma), thyroid cancer, endometrial cancer, vestibular schwannoma, blastoma, teratoma, pituitary cancer, vulvar cancer, thymoma, testicular cancer, bile duct cancer, pheochromocytoma, paraganglioma, and adenoid cystic carcinoma. In some embodiments, the aforementioned medicament is used to treat a disease selected from ovarian cancer, lung cancer, esophageal squamous cell carcinoma, colorectal cancer, renal cell carcinoma, and melanoma. BRIEF DESCRIPTION OF THE DRAWINGS

[0271] FIG1A shows the blocking effect of the anti-ILT4 antibody huP2-E3 on ILT4 and its downstream signaling pathways.

[0272] FIG1B shows the blocking effect of the anti-ILT4 antibody huP2-G9 on ILT4 and its downstream signaling pathways.

[0273] Figure 1C shows the blocking effect of the anti-ILT4 antibody huP2-C6 on ILT4 and its downstream signaling pathways.

[0274] Figure 1D shows the blocking effect of the anti-ILT4 antibody P2m on ILT4 and its downstream signaling pathways.

[0275] FIG2A shows the effect of the anti-ILT4 antibody huP2-G9 on the secretion of cytokine TNF-α by macrophages.

[0276] FIG2B shows the effect of the anti-ILT4 antibody huP2-C6 on the secretion of cytokine TNF-α by macrophages.

[0277] FIG2C shows the effect of the anti-ILT4 antibody huP2-E8 on the secretion of cytokine TNF-α by macrophages.

[0278] FIG2D shows the effect of the anti-ILT4 antibody P2m on the secretion of cytokine TNF-α by macrophages.

[0279] FIG3A shows the combined effect of anti-ILT4 antibody huP2-E3 and anti-PD-1 antibody in allogeneic MLR.

[0280] FIG3B shows the combined effect of anti-ILT4 antibody huP2-G9 and anti-PD-1 antibody in allogeneic MLR.

[0281] Figure 3C shows the combined effect of anti-ILT4 antibody huP2-C6 and anti-PD-1 antibody in allogeneic MLR.

[0282] Figure 3D shows the combined effect of anti-ILT4 antibody huP2-E8 and anti-PD-1 antibody in allogeneic MLR.

[0283] Figure 3E shows the combined effect of anti-ILT4 antibody P2m and anti-PD-1 antibody in allogeneic MLR. DETAILED DESCRIPTION

[0284] the term

[0285] In order to make the present disclosure more easily understood, certain technical and scientific terms are described below. Unless otherwise specifically defined herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

[0286] As used in the specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0287] Unless the context clearly requires otherwise, in the patent specification and claims, the words "comprising," "having," "including," and the like should be construed in the sense of "including but not limited to," rather than in an exclusive or exhaustive sense.

[0288] The term "cytokine" is a general term for proteins released by one cell population that act as intercellular mediators on other cells. Examples of such cytokines include lymphokines, monokines, chemokines, and traditional polypeptide hormones. Exemplary cytokines include mIL-2, IFNγ, TNFα, CCL-2, and IL-6.

[0289] The term "and / or" is intended to include both "and" and "or". For example, the phrase "A, B and / or C" is intended to include each of the following: A, B and C; A, B or C; A or C; A or B; B or C; A and C; A and B; B and C; A (alone); B (alone); and C (alone).

[0290] The three letter and one letter codes for amino acids used in this disclosure are as described in J. biol. chem, 243, p3558 (1968).

[0291] The term "ILT4" refers to the full-length ILT4 protein, and human ILT4 has the amino acid sequence of SEQ ID NO: 3. Amino acid sequences of ILT4 molecules from non-human species (eg, mouse, monkey, rabbit, dog, pig, etc.) are available from public resources.

[0292] The term "αPD-1" refers to an anti-PD-1 antibody.

[0293] The term "amino acid" refers to naturally occurring and synthetic amino acids, as well as amino acid analogs and amino acid mimetics that function in a manner similar to naturally occurring amino acids. Naturally occurring amino acids are those encoded by the genetic code, as well as those that are later modified, such as hydroxyproline, γ-carboxyglutamate, and O-phosphoserine. Amino acid analogs refer to compounds that have the same basic chemical structure as naturally occurring amino acids (i.e., an alpha carbon bound to a hydrogen, a carboxyl group, an amino group, and an R group), such as homoserine, norleucine, methionine sulfoxide, and methionine methylsulfonium. Such analogs have modified R groups (e.g., norleucine) or modified peptide backbones, but retain the same basic chemical structure as naturally occurring amino acids. Amino acid mimetics refer to chemical compounds that have a structure that is different from the general chemical structure of an amino acid, but function in a manner similar to naturally occurring amino acids.

[0294] The term "amino acid mutation" includes amino acid substitutions (also known as amino acid replacements), deletions, insertions, and modifications. Any combination of substitutions, deletions, insertions, and modifications can be performed to achieve the final construct, as long as the final construct possesses the desired properties, such as reduced binding to Fc receptors. Amino acid sequence deletions and insertions include deletions and insertions at the amino and / or carboxyl termini of the polypeptide chain. Specific amino acid mutations can be amino acid substitutions. In one embodiment, the amino acid mutation is a non-conservative amino acid substitution, i.e., replacing one amino acid with another amino acid having different structural and / or chemical properties. Amino acid substitutions include replacement with non-naturally occurring amino acids or with derivatives of the 20 natural amino acids (e.g., 4-hydroxyproline, 3-methylhistidine, ornithine, homoserine, 5-hydroxylysine). Amino acid mutations can be generated using genetic or chemical methods known in the art. Genetic methods can include site-directed mutagenesis, PCR, gene synthesis, and the like. It is expected that methods other than genetic engineering to alter amino acid side chain groups, such as chemical modification, may also be useful. Various names may be used herein to refer to the same amino acid mutation. Herein, the amino acid residue at a specific position may be indicated using the position+amino acid residue format. For example, 102S indicates that the amino acid residue at position 102 is S. C102S indicates that the amino acid residue at position 102 has mutated from C to S. It should be understood that when an amino acid sequence is defined in a claim using the position+residue format, the amino acid at that position before the mutation does not constitute a limitation to the technical solution.

[0295] The term "antibody" is used in the broadest sense and encompasses various antibody structures, including but not limited to monoclonal antibodies, polyclonal antibodies; monospecific antibodies, multispecific antibodies (e.g., bispecific antibodies); full-length antibodies and antibody fragments (or antigen-binding fragments, or antigen-binding portions), so long as they exhibit the desired antigen-binding activity.

[0296] "Native antibodies" refer to naturally occurring immunoglobulin molecules. For example, natural IgG antibodies are heterotetrameric glycoproteins of approximately 150,000 daltons, consisting of two light chains and two heavy chains bound by disulfide bonds. From N to C-terminus, each heavy chain has a variable region (VH), also known as a variable heavy domain, a heavy chain variable region, followed by a heavy chain constant region, and the natural IgG heavy chain constant region typically contains three constant domains (CH1, CH2, and CH3). Similarly, from N to C-terminus, each light chain has a variable region (VL), also known as a variable light domain, or a light chain variable domain, followed by a constant light domain (light chain constant region, CL). The terms "full-length antibody," "complete antibody," and "whole antibody" are used interchangeably herein and refer to antibodies having a structure substantially similar to that of a natural antibody structure or having a heavy chain of an Fc region as defined herein. A natural complete antibody light chain comprises a light chain variable region VL and a constant region CL, wherein VL is located at the amino terminus of the light chain, and the light chain constant region comprises a kappa chain and a lambda chain; a heavy chain comprises a variable region VH and constant regions (CH1, CH2, and CH3), wherein VH is located at the amino terminus of the heavy chain, and the constant region is at the carboxyl terminus, with CH3 being closest to the carboxyl terminus of the polypeptide. The heavy chain may belong to any isotype, including IgG (including IgG1, IgG2, IgG3, and IgG4 subtypes), IgA (including IgA1 and IgA2 subtypes), IgM, and IgE.

[0297] The term "variable region" or "variable domain" of an antibody refers to the domain of an antibody heavy or light chain involved in antigen binding. Herein, the heavy chain variable region (VH) and light chain variable region (VL) of an antibody each comprise four conserved framework regions (FRs) and three complementarity determining regions (CDRs). The term "complementarity determining region" or "CDR" refers to the region within the variable domain that primarily contributes to antigen binding; "framework" or "FR" refers to the variable domain residues excluding the CDR residues. The VH comprises three CDR regions: HCDR1, HCDR2, and HCDR3; the VL comprises three CDR regions: LCDR1, LCDR2, and LCDR3. Each VH and VL is composed of three CDRs and four FRs, arranged from the amino terminus (also called the N-terminus) to the carboxyl terminus (also called the C-terminus), in the following order: FR1, CDR1, FR2, CDR2, FR3, CDR3, FR4.

[0298] The amino acid sequence boundaries of CDRs can be determined by various well-known schemes, for example: "Kabat" numbering convention (see Kabat et al. (1991), "Sequences of Proteins of Immunological Interest", 5th edition, Public Health Service, National Institutes of Health, Bethesda, MD), "Chothia" numbering convention, "ABM" numbering convention, "contact" numbering convention (see Martin, ACR. Protein Sequence and Structure Analysis of Antibody Variable Domains [J]. 2001) and ImMunoGenTics (IMGT) numbering convention (Lefranc, MP et al., Dev. Comp. Immunol., 27, 55-77 (2003); Front Immunol. 2018 Oct 16; 9: 2278), etc. The correspondence between various numbering systems is well known to those skilled in the art, and is exemplified as shown in Table 1 below.

[0299] Table 1. Relationships between CDR numbering systems

[0300] Unless otherwise indicated, the variable regions and CDRs in the disclosed embodiments are all subject to the "Kabat" numbering convention. Although in specific embodiments, a numbering system (such as Kabat) is used to define amino acid residues, corresponding technical solutions using other numbering systems will be considered equivalent technical solutions.

[0301] The term "antibody fragment" refers to a molecule other than an intact antibody that comprises a portion of an intact antibody that binds to the antigen to which the intact antibody binds. Examples of antibody fragments include, but are not limited to, Fv, Fab, Fab', Fab'-SH, F(ab')2, single-domain antibodies, single-chain Fab (scFab), diabodies, linear antibodies, single-chain antibodies (e.g., scFv); and multispecific antibodies formed from antibody fragments.

[0302] The term "Fc region" or "fragment crystallizable region" is used to define the C-terminal region of the antibody heavy chain, including native Fc regions and reconstructed Fc regions. In some embodiments, the Fc region comprises two identical or different subunits. In some embodiments, the Fc region of a human IgG heavy chain is defined as extending from the amino acid residue at position Cys226 or from Pro230 to its carboxyl terminus. Suitable Fc regions for the antibodies described herein include the Fc regions of human IgG1, IgG2 (IgG2A, IgG2B), IgG3, and IgG4. In some embodiments, the boundaries of the Fc region can also vary, such as by deleting the C-terminal lysine in the Fc region (residue 447 according to the EU numbering system) or by deleting the C-terminal glycine and lysine in the Fc region (residues 446 and 447 according to the EU numbering system). Unless otherwise indicated, the numbering convention for the Fc region is the EU numbering system, also known as the EU index.

[0303] The term "chimeric" antibody refers to an antibody in which a portion of the heavy and / or light chain is derived from a particular source or species, while the remainder of the heavy and / or light chain is derived from a different source or species.

[0304] The term "humanized" antibody is an antibody that retains the reactivity of a non-human antibody while having lower immunogenicity in humans. For example, this can be achieved by retaining the non-human CDR regions and replacing the rest of the antibody with their human counterparts (i.e., the constant region and the framework region portion of the variable region).

[0305] The terms "human antibody," "humanized antibody," "fully human antibody," and "completely human antibody" are used interchangeably to refer to antibodies whose variable and constant regions are human sequences. The term encompasses antibodies that are derived from human genes but have altered sequences, for example, to reduce potential immunogenicity, increase affinity, or eliminate cysteines or glycosylation sites that may cause undesirable folding. The term encompasses antibodies that are recombinantly produced in non-human cells (which may confer glycosylation that is not characteristic of human cells). The term also encompasses antibodies that have been produced in transgenic mice containing some or all human immunoglobulin heavy and light chain loci. The term "human antibody" specifically excludes humanized antibodies.

[0306] The term "affinity" refers to the overall strength of the non-covalent interactions between a single binding site of a molecule (e.g., an antibody) and its binding ligand (e.g., an antigen). Unless otherwise indicated, as used herein, binding "affinity" refers to internal binding affinity, which reflects a 1:1 interaction between members of a binding pair (e.g., an antibody and an antigen). The affinity of a molecule X for its ligand Y can generally be represented by a dissociation constant (KD). Affinity can be measured by conventional methods known in the art, including those described herein.

[0307] As used herein, the term "kassoc" or "ka" refers to the association rate of a specific antibody-antigen interaction, and the term "kdis" or "kd" refers to the dissociation rate of a specific antibody-antigen interaction. The term "KD" refers to the dissociation constant, which is obtained from the ratio of kd to ka (i.e., kd / ka) and is expressed as molar concentration (M). The KD value of an antibody can be measured using methods well known in the art. For example, a biosensor system such as a system measuring surface plasmon resonance (e.g., Biacore) is used, or affinity in a solution is measured by solution equilibrium titration (SET).

[0308] The term "surface plasmon resonance" refers to an optical phenomenon that allows analysis of real-time interactions by detecting changes in protein concentration within a biosensor matrix, for example, using a BIAcore™ system (Biacore LifeSciences division of GE Healthcare, Piscataway, NJ).

[0309] The term "effector function" refers to those biological activities attributable to the Fc region of an antibody (either a native sequence Fc region or an amino acid sequence mutated Fc region) and varies with the antibody isotype. Examples of antibody effector functions include, but are not limited to, C1q binding and complement-dependent cytotoxicity, Fc receptor binding, antibody-dependent cell-mediated cytotoxicity (ADCC), phagocytosis, downregulation of cell surface receptors (e.g., B cell receptors), and B cell activation.

[0310] The term "monoclonal antibody" refers to a group of substantially homogeneous antibodies, i.e., the amino acid sequences of the antibody molecules contained in the group are identical, except for possible natural mutations that may be present in small amounts. In contrast, polyclonal antibodies typically include a variety of different antibodies with different amino acid sequences in their variable domains, which are typically specific for different epitopes. "Monoclonal" should not be interpreted as requiring the production of antibodies by any particular method. In some embodiments, the antibodies provided herein are monoclonal antibodies.

[0311] The term "antigen" refers to a molecule or portion of a molecule that can be selectively bound by, for example, an antigen binding protein (including, for example, an antibody). An antigen may have one or more epitopes that can interact with different antigen binding proteins (eg, antibodies).

[0312] The term "epitope" refers to an area or region on an antigen that is capable of specific binding to an antibody or its antigen-binding fragment. An epitope can be formed by a continuous string of amino acids (linear epitope) or contain non-continuous amino acids (conformational epitope), for example, when the antigen folds and becomes spatially close. The difference between a conformational epitope and a linear epitope is that the antibody loses binding to the conformational epitope in the presence of a denaturing solvent. An epitope contains at least 3, at least 4, at least 5, at least 6, at least 7, or 8-10 amino acids in a unique spatial conformation. Screening for antibodies that bind to a specific epitope (i.e., those that bind to the same epitope) can be performed using routine methods in the art, such as, but not limited to, alanine scanning, peptide blotting, peptide cleavage analysis, epitope excision, epitope extraction, chemical modification of the antigen (see Prot. Sci. 9 (2000) 487-496), and cross-blocking.

[0313] The terms "capable of specifically binding", "specific binding" or "binding" refer to an antibody that binds to an antigen or epitope with a higher affinity than to other antigens or epitopes. -7 M or less (e.g., about 1×10 -8 M, 1×10 -9 M, 1×10 -10 M, 1×10 -11 In some embodiments, the antibody binds to the antigen with an equilibrium dissociation constant (KD) of 10% or less (e.g., 1%) of the KD of the antibody binding to a nonspecific antigen (e.g., BSA, casein). KD can be measured using known methods, such as by However, an antibody that specifically binds to an antigen or an epitope thereof does not exclude cross-reactivity to other related antigens, for example, to corresponding antigens from other species (homologous), such as humans or monkeys, for example, Macaca fascicularis (cynomolgus, cyno), chimpanzee (Pan troglodytes) (chimpanzee, chimp) or marmoset (Callithrix jacchus (common marmoset, marmoset).

[0314] The terms "anti-ILT4 antibody" and "antibody that binds to ILT4" refer to an antibody that is capable of binding to ILT4 or an epitope thereof with sufficient affinity.

[0315] The term "antibody-dependent cellular cytotoxicity," "antibody-dependent cell-mediated cytotoxicity," or "ADCC" is a mechanism of inducing cell death that relies on the interaction of antibody-coated target cells with effector cells with lytic activity (such as natural killer cells (NK), monocytes, macrophages, and neutrophils) via Fc gamma receptors (Fc gamma R) expressed on effector cells. For example, NK cells express Fc gamma RIIIa, while monocytes express Fc gamma RI, Fc gamma RII, and Fc gamma RIIIa. The ADCC activity of the antibodies provided herein can be assessed using in vitro assays using antigen-expressing cells as target cells and NK cells as effector cells. Cell lysis is detected based on markers released from the lysed cells (e.g., radioactive substrates, fluorescent dyes, or native intracellular proteins).

[0316] The term "antibody-dependent cellular phagocytosis (ADCP)" refers to a mechanism by which antibody-coated target cells are eliminated by internalization by phagocytes, such as macrophages or dendritic cells.

[0317] The term "complement-dependent cytotoxicity" or "CDC" refers to a mechanism of cell death induction in which the Fc effector domain of a target-bound antibody binds to and activates the complement component C1q, which in turn activates the complement cascade, leading to target cell death. Activation of complement can also result in the deposition of complement components on the surface of target cells, which promote CDC by binding to complement receptors (e.g., CR3) on leukocytes.

[0318] The term "nucleic acid" is used interchangeably with the term "polynucleotide" in this article and refers to deoxyribonucleotides or ribonucleotides and polymers thereof in single-stranded or double-stranded form. The term encompasses nucleic acids containing known nucleotide analogs or modified backbone residues or connections, which are synthetic, naturally occurring, and non-naturally occurring, with binding properties similar to reference nucleic acids, and metabolized in a manner similar to reference nucleotides. Examples of such analogs include, but are not limited to, phosphorothioates, phosphoramidates, methylphosphonates, chiral-methylphosphonates, 2-O-methyl ribonucleotides, peptide-nucleic acids (PNAs).

[0319] "Isolated" nucleic acid refers to a nucleic acid molecule that has been separated from the components of its natural environment. An isolated nucleic acid encoding a polypeptide refers to one or more nucleic acid molecules encoding the polypeptide, including such one or more nucleic acid molecules in a single vector or separate vectors, and such one or more nucleic acid molecules present in one or more locations in a host cell. Unless otherwise indicated, a particular nucleic acid sequence also implicitly encompasses conservatively modified variants thereof (e.g., degenerate codon substitutions) and complementary sequences as well as explicitly specified sequences. Specifically, as described in detail below, degenerate codon substitutions can be obtained by generating sequences in which the third position of one or more selected (or all) codons is substituted with mixed bases and / or deoxyinosine residues.

[0320] The terms "polypeptide" and "protein" are used interchangeably herein to refer to a polymer of amino acid residues. The term applies to amino acid polymers in which one or more amino acid residues is an artificial chemical mimetic of a corresponding naturally occurring amino acid, as well as to naturally occurring amino acid polymers and non-naturally occurring amino acid polymers. Unless otherwise indicated, a particular polypeptide sequence also implicitly encompasses conservatively modified variants thereof.

[0321] The term sequence "identity" refers to the degree (percentage) to which the amino acids / nucleic acids of the two sequences are identical at equivalent positions when the two sequences are optimally aligned; gaps are introduced, if necessary, to obtain the maximum sequence identity percentage, and any conservative substitutions are not considered part of the sequence identity. To determine the percentage of sequence identity, alignment can be achieved by techniques known in the art, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN, ALIGN-2, or Megalign (DNASTAR) software. One skilled in the art can determine parameters suitable for measuring alignment, including any algorithm required to achieve maximum alignment over the full length of the compared sequences.

[0322] The term "vector" means a polynucleotide molecule capable of transporting another polynucleotide connected thereto. One type of vector is a "plasmid", which refers to a circular double-stranded DNA loop, wherein additional DNA segments can be connected. Another type of vector is a viral vector, such as an adeno-associated viral vector (AAV or AAV2), in which additional DNA segments can be connected to the viral genome. Some vectors can replicate autonomously (for example, bacterial vectors and additional mammalian vectors with bacterial replication origins) in the host cell in which they are introduced. Other vectors (for example, non-additional mammalian vectors) can be integrated into the genome of the host cell after being introduced into the host cell, thereby replicating together with the host genome. The term "expression vector" or "expression construct" refers to a vector that can transform a host cell and contains a nucleic acid sequence for the expression of one or more heterologous coding regions that are operably connected thereto, including guidance and / or control (together with the host cell). Expression constructs can include but are not limited to affecting or controlling transcription, translation and affecting the sequence of RNA splicing of the coding region operably connected thereto when there are introns.

[0323] The terms "host cell," "host cell line," and "host cell culture" are used interchangeably and refer to cells into which exogenous nucleic acid has been introduced, including the progeny of such cells. Host cells include "transformants" and "transformed cells," which include the primary transformed cell and progeny derived therefrom, without regard to the number of passages. Progeny may not be completely identical to the parent cell in nucleic acid content, but may contain mutations. Mutant progeny are included herein as having the same function or biological activity as the cell screened or selected for in the initial transformed cell. Host cells include prokaryotic and eukaryotic host cells, wherein eukaryotic host cells include, but are not limited to, mammalian cells, insect cell lines, plant cells, and fungal cells. Mammalian host cells include human, mouse, rat, dog, monkey, pig, goat, cow, horse, and hamster cells, including but not limited to Chinese hamster ovary (CHO) cells, NSO, SP2 cells, HeLa cells, baby hamster kidney (BHK) cells, monkey kidney cells (COS), human hepatocellular carcinoma cells (e.g., Hep G2), A549 cells, 3T3 cells, and HEK-293 cells.Fungal cells include yeast and filamentous fungal cells, including, for example, Pichia pastoris, Pichia finlandica, Pichia trehalophila, Pichia koclamae, Pichia membranaefaciens, Pichia minuta (Ogataea minuta, Pichia lindneri), Pichia truncatula, Pichia thermotolerans, Pichia salictaria, Pichia guercuum, Pichia pijperi, Pichia stiptis, Pichia methanolica, Pichia sp., Saccharomyces cerevisiae, Saccharomyces cerevisiae, Hansenula polymorpha, polymorpha), Kluyveromyces spp., Kluyveromyces lactis, Candida albicans, Aspergillus nidulans, Aspergillus niger, Aspergillus oryzae, Trichoderma reesei, Chrysosporium lucknowense, Fusarium sp., Fusarium gramineum, Fusarium venenatum, Physcomitrella patens, and Neurospora crassa. Pichia, any Saccharomyces spp., Hansenula polymorpha, any Kluyveromyces spp., Candida albicans, any Aspergillus spp., Trichoderma reesei, Chrysosporium lucknowense, any Fusarium spp., Yarrowia lipolytica, and Neurospora crassa.

[0324] "Optional" or "optionally" means that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0325] The term "pharmaceutical composition" refers to a mixture containing one or more anti-ILT4 antibodies described herein and other chemical components, such as physiologically / pharmaceutically acceptable carriers and excipients.

[0326] The term "pharmaceutically acceptable carrier, diluent, or excipient" refers to an ingredient in a pharmaceutical formulation that is different from the active ingredient and is non-toxic to the subject. Pharmaceutically acceptable carriers, diluents, or excipients include, but are not limited to, buffers, excipients, stabilizers, or preservatives.

[0327] The term "subject" or "individual" includes humans and non-human animals. Non-human animals include all vertebrates (e.g., mammals and non-mammals) such as non-human primates, sheep, dogs, cows, chickens, amphibians and reptiles. Unless otherwise indicated, the terms "patient" or "subject" are used interchangeably herein. In certain embodiments, the individual or subject is a human.

[0328] "Administering" or "administering," as it applies to an animal, human, experimental subject, cell, tissue, organ or biological fluid, refers to the contact of an exogenous drug, therapeutic agent, diagnostic agent or composition with the animal, human, subject, cell, tissue, organ or biological fluid.

[0329] The term "sample" refers to a collection (e.g., fluid, cell, or tissue) isolated from a subject, as well as fluids, cells, or tissues present in a subject. Exemplary samples are biological fluids such as blood, serum and serosal fluid, plasma, lymph, urine, saliva, cystic fluid, tears, excretions, sputum, mucosal secretions of secretory tissues or organs, vaginal secretions, ascites, pleura, pericardium, peritoneum, fluids of the abdominal cavity and other body cavities, fluids collected by bronchial lavage, synovial fluid, liquid solutions in contact with a subject or biological source, such as culture medium (including conditioned medium), lavage fluid, etc., tissue biopsy samples, fine needle aspiration, surgically removed tissue, organ culture, or cell culture.

[0330] "Treatment" and "treatment" (and grammatical variations thereof) refer to clinical intervention in the individual being treated and can be performed for prevention or during the course of clinical pathology. Desired effects of treatment include, but are not limited to, preventing the occurrence or recurrence of the disease, alleviating symptoms, alleviating / reducing any direct or indirect pathological consequences of the disease, preventing metastasis, reducing the rate of disease progression, improving or alleviating the disease state, and remission or improved prognosis. In some embodiments, the antibodies of the present disclosure are used to delay the development of the disease or slow the progression of the disease.

[0331] An "effective amount" is generally an amount sufficient to reduce the severity and / or frequency of symptoms, eliminate these symptoms and / or potential causes, prevent the occurrence of symptoms and / or their potential causes, and / or ameliorate or improve the damage caused by or associated with the disease state (e.g., lung disease). In some embodiments, an effective amount is a therapeutically effective amount or a prophylactically effective amount.

[0332] A "therapeutically effective amount" is an amount sufficient to treat a disease state or symptom, particularly a state or symptom associated with the disease state, or otherwise prevent, hinder, delay or reverse the progression of the disease state or any other undesirable symptoms associated with the disease in any way. A "prophylactic effective amount" is an amount that, when administered to a subject, will have a predetermined preventive effect, such as preventing or delaying the onset (or recurrence) of the disease state, or reducing the likelihood of the onset (or recurrence) of the disease state or related symptoms. Complete treatment or prevention may not occur after administering one dose, but may occur after administering a series of doses. Thus, a therapeutic or prophylactic effective amount can be administered in one or more administrations. "Therapeutically effective amount" and "prophylactic effective amount" may vary depending on a variety of factors: such as the disease state, age, sex, and weight of the individual, and the ability of the therapeutic agent or therapeutic combination to elicit a desired response in the individual. Exemplary indicators of an effective therapeutic agent or therapeutic combination include, for example, improved health status of the patient.

[0333] The term "immune checkpoint" refers to a group of molecules on the cell surface of CD4 T cells and CD8 T cells. These molecules can effectively act as "brakes" to downregulate or inhibit anti-tumor immune responses. Immune checkpoint molecules include but are not limited to programmed death-1 (PD-1), cytotoxic T lymphocyte antigen 4 (CTLA-4), B7H1, B7H4, OX-40, CD137, CD40 and LAG-3, which directly inhibit immune cells.

[0334] The immune checkpoint inhibitors for the present disclosure are substances that inhibit the function of immune checkpoint molecules. There are no particular restrictions on immune checkpoint inhibitors, as long as the inhibitor is a substance that can inhibit the function (signal) of immune checkpoint molecules. The immune checkpoint inhibitors that can be used in the present disclosure method include but are not limited to PD-1, PD-L2, CTLA-4, TIM-3, LAG-3, VISTA, BTLA, TIGIT, LAIR1, CD160, 2B4, CEACAM (e.g., CEACAM-1, CEACAM-3 and / or CEACAM-5) and / or TGFRβ inhibitors. The inhibition of inhibitory molecules can be implemented by suppressing at the DNA, RNA or protein levels. In embodiments, inhibitory nucleic acids (e.g., dsRNA, siRNA or shRNA) can be used to suppress the expression of inhibitory molecules. In other embodiments, the inhibitor of inhibitory signals is a polypeptide bound to inhibitory molecules, for example, a soluble ligand or antibody. Examples of the immune checkpoint inhibitor used in the present disclosure may include, but are not particularly limited to, anti-PD-1 antibodies, anti-PD-L1 antibodies, and anti-CTLA-4 antibodies, and anti-PD-1 antibodies may be preferred.

[0335] target molecule

[0336] "ILT4" should be understood broadly and is intended to cover various forms of ILT4 molecules at various stages in mammals, such as but not limited to molecules produced during the amplification, replication, transcription, splicing, processing, translation, and modification of the ILT4 gene (e.g., precursor ILT4, mature ILT4, membrane-expressed ILT4, ILT4 splice variants, modified ILT4, or fragments thereof); the term also covers artificially prepared or in vitro expressed ILT4.

[0337] Disclosed anti-ILT4 antibodies

[0338] The present disclosure provides anti-ILT4 antibodies, which have many advantageous properties, such as good in vitro killing activity, therapeutic activity, safety, pharmacokinetic properties and drugability (such as yield, purity and stability, etc.).

[0339] Exemplary anti-ILT4 antibodies

[0340] The embodiments of the present disclosure disclose antibody series P1-B4, P1-B9, P1-D10, P2-E8, P2-C10, P2-F4, P2-B3, P2-E7, P2-G4, P2-C4, P2-E11, P1-F7, P2-E3, P2-F10, P2-G9, P1-C4, P1-G7, P2-C7, P2-C6, P1-D7, P1-E11, P2-B9, P2-C2, and P2-E10. Antibodies P2-G9 and P2-C6 are used as examples to describe the antibodies of the present disclosure.

[0341] Exemplary, the anti-ILT4 antibody of the present disclosure comprises a heavy chain variable region and a light chain variable region, wherein:

[0342] a. the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 of SEQ ID NO: 184 or 185, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 of SEQ ID NO: 187 or 186, respectively; or the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 of SEQ ID NO: 32, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 of SEQ ID NO: 33, respectively; or

[0343] b. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of any one of SEQ ID NOs: 211, 205, 206, 207, 208, 209 or 210, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of any one of SEQ ID NOs: 212, 213 or 214; or the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of SEQ ID NO: 40, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 41.

[0344] Exemplary, the anti-ILT4 antibody of the present disclosure comprises a heavy chain variable region and a light chain variable region, wherein:

[0345] a. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 184, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 187; or

[0346] b. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 211, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 212.

[0347] Exemplarily, in the anti-ILT4 antibodies disclosed herein, the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2 and LCDR3 of the light chain variable region are defined according to the same numbering convention selected from Kabat, IMGT, Chothia, AbM and Contact.

[0348] Exemplary, the anti-ILT4 antibody of the present disclosure comprises a heavy chain variable region and a light chain variable region, wherein:

[0349] The HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 105, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 120, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 121, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 114, the LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and the LCDR3 comprises the amino acid sequence of SEQ ID NO: 119.

[0350] Exemplary, the anti-ILT4 antibody of the present disclosure comprises a heavy chain variable region and a light chain variable region, wherein:

[0351] the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 135, HCDR2 comprises the amino acid sequence of SEQ ID NO: 203, 136, 201, 202 or 204, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 137, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 138, LCDR2 comprises the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140;

[0352] Preferably, HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 135, HCDR2 comprises the amino acid sequence of SEQ ID NO: 203, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 137, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 138, LCDR2 comprises the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140.

[0353] Exemplarily, in the anti-ILT4 antibodies disclosed herein, the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region and the LCDR1, LCDR2 and LCDR3 of the light chain variable region are defined according to the Kabat numbering convention.

[0354] Exemplary, the anti-ILT4 antibody disclosed herein, wherein,

[0355] a. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 260, HCDR2 comprises the amino acid sequence of SEQ ID NO: 261, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 262, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 263, LCDR2 comprises the amino acid sequence of SEQ ID NO: 264, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0356] b. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 267, HCDR2 comprises the amino acid sequence of SEQ ID NO: 268, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 269, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 270, LCDR2 comprises the amino acid sequence of SEQ ID NO: 271, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140;

[0357] The CDR regions are determined according to the IMGT numbering rules.

[0358] Exemplary, the anti-ILT4 antibody disclosed herein, wherein,

[0359] the heavy chain variable region HCDR1 comprises the amino acid sequence set forth in SEQ ID NO:260, HCDR2 comprises the amino acid sequence set forth in SEQ ID NO:261, and HCDR3 comprises the amino acid sequence set forth in SEQ ID NO:262, and the light chain variable region LCDR1 comprises the amino acid sequence set forth in SEQ ID NO:263, LCDR2 comprises the amino acid sequence set forth in SEQ ID NO:264, and LCDR3 comprises the amino acid sequence set forth in SEQ ID NO:119;

[0360] The CDR regions are determined according to the IMGT numbering rules.

[0361] Exemplary, the anti-ILT4 antibody disclosed herein, wherein,

[0362] a. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 265, HCDR2 comprises the amino acid sequence of SEQ ID NO: 266, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 121, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or

[0363] b. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 272, HCDR2 comprises the amino acid sequence of SEQ ID NO: 273, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 137, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 138, LCDR2 comprises the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140;

[0364] The CDR regions are determined according to the Chothia numbering convention.

[0365] Exemplary, the anti-ILT4 antibody disclosed herein, wherein,

[0366] the heavy chain variable region HCDR1 comprises the amino acid sequence set forth in SEQ ID NO:265, HCDR2 comprises the amino acid sequence set forth in SEQ ID NO:266, and HCDR3 comprises the amino acid sequence set forth in SEQ ID NO:121, and the light chain variable region LCDR1 comprises the amino acid sequence set forth in SEQ ID NO:114, LCDR2 comprises the amino acid sequence set forth in SEQ ID NO:109, and LCDR3 comprises the amino acid sequence set forth in SEQ ID NO:119;

[0367] The CDR regions are determined according to the Chothia numbering convention.

[0368] Exemplary, the anti-ILT4 antibodies disclosed herein are murine antibodies, chimeric antibodies, humanized antibodies, or fully human antibodies. In some embodiments, the antibody is a chimeric antibody. In some embodiments, the antibody is a fully human antibody. In some embodiments, the antibody is a humanized antibody.

[0369] Exemplary, the anti-ILT4 antibodies disclosed herein comprise a framework region (FR) of a human antibody.

[0370] Exemplary, anti-ILT4 antibodies of the present disclosure, wherein:

[0371] a. the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 184, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 187; or

[0372] b. the heavy chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 211, and the light chain variable region comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 212.

[0373] Exemplary, in the anti-ILT4 antibody disclosed herein, the heavy chain variable region has FR1, FR2, FR3 derived from IGHV4-31*01 and FR4 derived from IGHJ1*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 1E, 27S, 30T, 44K, 71R and 76S; and / or the light chain variable region has FR1, FR2, FR3 derived from IGKV1-39*01 and FR4 derived from IGKJ4*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 43S, 48V and 71Y. In some embodiments, the anti-ILT4 antibody comprises: a heavy chain variable region HCDR1 comprising the amino acid sequence of SEQ ID NO: 105, a HCDR2 comprising the amino acid sequence of SEQ ID NO: 120, and a HCDR3 comprising the amino acid sequence of SEQ ID NO: 121, and a heavy chain variable region FR comprising one or more amino acid substitutions selected from the group consisting of 1E, 27S, 30T, 44K, 71R, and 76S; and a light chain variable region LCDR1 comprising the amino acid sequence of SEQ ID NO: 114, a LCDR2 comprising the amino acid sequence of SEQ ID NO: 109, and a LCDR3 comprising the amino acid sequence of SEQ ID NO: 119, and a light chain variable region FR comprising one or more amino acid substitutions selected from the group consisting of 43S, 48V, and 71Y. In some embodiments, the variable regions and CDRs are defined according to the Kabat numbering convention.

[0374] Exemplary, in the anti-ILT4 antibody disclosed herein, the heavy chain variable region has FR1, FR2, FR3 derived from IGHV1-18*01 and FR4 derived from IGHJ6*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 1E, 43E, 69L, 71V, 73K, 76N and 93T; and / or the light chain variable region has FR1, FR2, FR3 derived from IGKV4-1*01 or IGKV3-11*01 and FR4 derived from IGKJ4*01, and is unsubstituted or has one or more amino acid substitutions selected from the group consisting of 4L, 43P, 45K, 58I, 68R and 85T. In some embodiments, the anti-ILT4 antibody comprises: a heavy chain variable region HCDR1 comprising the amino acid sequence of SEQ ID NO: 135; a HCDR2 comprising the amino acid sequence of SEQ ID NO: 203, 136, 201, 202, or 204; and a HCDR3 comprising the amino acid sequence of SEQ ID NO: 137; and the heavy chain variable region FR comprises one or more amino acid substitutions selected from the group consisting of 1E, 43E, 69L, 71V, 73K, 76N, and 93T; and a light chain variable region LCDR1 comprising the amino acid sequence of SEQ ID NO: 138, LCDR2 comprising the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprising the amino acid sequence of SEQ ID NO: 140; and the light chain variable region FR comprises one or more amino acid substitutions selected from the group consisting of 4L, 43P, 45K, 58I, 68R, and 85T. In some embodiments, the variable regions and CDRs are defined according to the Kabat numbering convention.

[0375] Exemplary, the anti-ILT4 antibody disclosed herein is an antibody fragment; in some embodiments, the antibody fragment is selected from Fab, Fab′, F(ab′)2, Fd, Fv, scFv, dsFv or dAb.

[0376] Exemplary anti-ILT4 antibodies disclosed herein comprise a heavy chain constant region and a light chain constant region. In some embodiments, the heavy chain constant region is a human IgG1 or IgG4 heavy chain constant region. In some embodiments, the heavy chain constant region comprises 234A and 235A mutations, with the mutations numbered according to the EU index. In some embodiments, the light chain constant region is a human kappa light chain constant region. In some embodiments, the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 240 or 171, and the light chain constant region comprises the amino acid sequence of SEQ ID NO: 172.

[0377] Exemplary, the anti-ILT4 antibody disclosed herein comprises a heavy chain and a light chain, wherein,

[0378] a. the heavy chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 228, and the light chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 229; or

[0379] b. the heavy chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 234, and the light chain comprises an amino acid sequence that is at least 70% (e.g., at least 70%, 80%, 85%, 90%, 95%, 98%, or 99%) identical to SEQ ID NO: 235.

[0380] Exemplary, the anti-ILT4 antibody disclosed herein comprises a heavy chain and a light chain, wherein,

[0381] a. the heavy chain comprises the amino acid sequence of SEQ ID NO: 228, and the light chain comprises the amino acid sequence of SEQ ID NO: 229; or

[0382] b. The heavy chain comprises the amino acid sequence of SEQ ID NO: 234, and the light chain comprises the amino acid sequence of SEQ ID NO: 235.

[0383] Exemplarily, the present disclosure further provides an isolated anti-ILT4 antibody that competes with any of the above anti-ILT4 antibodies for binding to human ILT4 or an epitope thereof.

[0384] Exemplarily, the anti-ILT4 antibodies provided herein specifically bind to human ILT4 and do not bind to other LILR family members ILT2, ILT3, LILRB5, LILRA1, LILRA2, LILRA3, LILRA4, LILRA5 and / or LILRA6.

[0385] For example, the anti-ILT4 antibody isolated in the present disclosure has a higher binding ability to the ILT4 protein than the control antibody. Specifically, the anti-ILT4 antibody isolated in the present disclosure has a binding ability of less than 1×10 -8 M (e.g. less than 8×10 -9 M, less than 5×10 -9 M, less than 2×10 -9M, less than 1×10 -9 M, less than 8×10 -10 M, less than 5×10 -10 M, less than 2×10 -10 M, less than 1×10 -10 M, less than 8×10 -11 M, less than 5×10 -11 M) KD values ​​for binding to human ILT4 as measured by surface plasmon resonance (Biacore).

[0386] Illustratively, the humanized anti-ILT4 antibodies provided herein can effectively relieve the inhibitory effect of ILT4 and promote 3A9 cells to secrete higher levels of mIL-2.

[0387] Illustratively, the humanized anti-ILT4 antibodies provided herein can effectively promote the transformation of macrophages to the M1 phenotype and secrete high levels of the pro-inflammatory cytokine TNF-α.

[0388] Exemplarily, the humanized anti-ILT4 antibodies (eg, huP2-G9) provided herein can induce dendritic cells to secrete higher levels of pro-inflammatory cytokines or chemokines in the presence of IL-10 in an immunosuppressive environment.

[0389] Exemplarily, the humanized anti-ILT4 antibodies provided herein can effectively block the binding of ILT4 to HLA-G.

[0390] Illustratively, the humanized anti-ILT4 antibodies provided herein can effectively block the binding of ILT4 to HLA-G, and the blocking activity is stronger than that of the control antibodies MK and JTX.

[0391] Antibody structure

[0392] In certain embodiments, the antibodies provided herein are full-length antibodies.

[0393] In certain embodiments, the antibodies provided herein are antibody fragments.

[0394] In one embodiment, the antibody fragment is a Fab, Fab', Fab'-SH or F(ab')2 fragment, in particular a Fab fragment. "Fab" is a monovalent fragment consisting of the VL, VH, CL and CH1 domains. "Fab fragment" can be produced by papain cleavage of an antibody. "Fab'" contains VL, CL as well as VH and CH1, and also contains a region between the CH1 and CH2 domains so that an interchain disulfide bond can be formed between the two heavy chains of the two Fab' fragments to form a F(ab')2 molecule. "Fab'-SH" is a Fab' fragment in which the cysteine ​​residues in the constant region have a free sulfhydryl group. "F(ab')2" is a bivalent fragment comprising two Fab fragments linked by a disulfide bond at the hinge region.

[0395] In another embodiment, the antibody fragment is a diabody, triabody, or tetrabody. A diabody is an antibody fragment with two antigen-binding sites, which contains a linked VH and VL in the same polypeptide chain (VH-VL). By using a linker that is too short to prevent pairing between the two domains on the same chain, these domains are forced to pair with complementary domains from another chain, thereby generating two antigen-binding sites. The two antigens can be the same or different.

[0396] In another embodiment, the antibody fragment is a single-chain Fab fragment. "Single-chain Fab fragment" or "scFab" is a polypeptide consisting of VH, CH1, VL, CL and a linker, wherein the antibody domain and the linker have one of the following orders in the N-terminal to C-terminal direction: a) VH-CH1-linker-VL-CL, b) VL-CL-linker-VH-CH1, c) VH-CL-linker-VL-CH1 or d) VL-CH1-linker-VH-CL. In one embodiment, the linker is a polypeptide having at least 30 amino acids. In another embodiment, the linker is a polypeptide having between 32 and 50 amino acids. The single-chain Fab fragment is stabilized via the natural disulfide bond between CL and CH1. In addition, these single-chain Fab molecules can be further stabilized by inserting cysteine ​​residues (e.g., position 44 in the heavy chain variable region and position 100 in the light chain variable region, according to Kabat numbering) to produce interchain disulfide bonds.

[0397] In another embodiment, the antibody fragment is an Fv fragment consisting of the VH and VL domains of a single arm of an antibody.

[0398] In another embodiment, the antibody fragment is a single-chain variable fragment (scFv). "scFv" is a fusion protein comprising at least one antibody fragment containing a light chain variable region and at least one antibody fragment containing a heavy chain variable region, wherein the light chain variable region and the heavy chain variable region are connected by a short flexible peptide linker, can be expressed as a single-chain polypeptide, and wherein the scFv retains the specificity of the intact antibody from which it is derived. Unless otherwise specified, scFv herein can have the VL and VH variable regions in any order, for example, relative to the N-terminus and C-terminus of the polypeptide, the scFv can comprise VL-linker-VH or can comprise VH-linker-VL.

[0399] In another embodiment, the antibody fragment is a dsFv obtained by linking polypeptides in which one amino acid residue in each of VH and VL is substituted with a cysteine ​​residue via a disulfide bond between the cysteine ​​residues. The amino acid residue to be substituted with the cysteine ​​residue can be selected based on the three-dimensional structure prediction of the antibody according to a known method (Protein Engineering. 7: 697 (1994)).

[0400] In another embodiment, the antibody fragment is a single domain antibody (dAb).A single domain antibody is an antibody fragment that comprises all or part of the heavy chain variable domain or all or part of the light chain variable domain of an antibody.

[0401] In certain embodiments, the antibodies provided herein are chimeric antibodies. In one example, a chimeric antibody comprises a non-human variable region (e.g., a variable region derived from a mouse, rat, hamster, rabbit, or non-human primate, such as a monkey) and a human constant region. In another example, a chimeric antibody is a "class-switched" antibody in which the class or subclass has been changed from that of the parent antibody.

[0402] In certain embodiments, antibody is a humanized antibody. Generally, non-human antibodies are passed through humanization to reduce immunogenicity to people, while retaining the specificity and affinity of the parent non-human antibody. Generally, humanized antibodies comprise one or more variable regions, wherein CDR or its portion are derived from non-human antibodies, and FR or its portion are derived from human antibodies. Optionally, humanized antibodies also may comprise a part for human constant region. In some embodiments, some FR residues in humanized antibodies may be substituted with corresponding residues from non-human antibodies (for example, antibodies providing CDR sequences).

[0403] Humanized antibodies and methods for their generation are reviewed in, for example, Almagro and Fransson, Front. Biosci. 13:1619-1633 (2008), and further described in, for example, Riechmann et al., Nature 332:323-329 (1988); Queen et al., Proc. Nat'l Acad. Sci. USA 86:10029-10033 (1989); U.S. Patent Nos. 5,821,337, 7,527,791, 6,982,321 and 7,087,409; Kashmiri et al., Methods 36:25-34 (2005) (describing specificity determining region (SDR) grafting); Padlan, Mol. Immunol. 28:489-498 (1991) (describing "resurfuacing"); Dall'Acqua et al., Methods 36:43-60 (2005) (describing "FR shuffling"); and Osbourn et al., Methods 36:61-68 (2005) and Klimka et al., Br. J. Cancer 83:252-260 (2000) (describing the "guided selection" method of FR shuffling).

[0404] Human framework regions that can be used for humanization include, but are not limited to, framework regions selected using the "best-fit" method (see, e.g., Sims et al., J. Immunol. 151: 2296 (1993)); framework regions derived from the consensus sequence of human antibodies of a particular subgroup of light chain variable regions or heavy chain variable regions (see, e.g., Carter et al., Proc. Natl. Acad. Sci. USA, 89: 4285 (1992); and Presta et al., J. Immunol., 151: 2623 (1993)); human mature (somatically mutated) framework regions or human germline framework regions (see, e.g., Almagro and Fransson, Front. Biosci. 13: 1619-1633 (2008)); and framework regions obtained by screening FR libraries (see, e.g., Baca et al., J. Biol. Chem. 272: 10678-10684 (1997) and Rosok et al., J. Biol. Chem. 271: 22611-22618 (1996)).

[0405] Variants of anti-ILT4 antibodies

[0406] In certain embodiments, amino acid sequence variants of the anti-ILT4 antibodies provided herein are encompassed. For example, it may be desirable to improve the binding affinity and / or other biological properties of the antibody. Amino acid sequence variants of the antibody may be prepared by introducing suitable modifications into the nucleotide sequence encoding the antibody, or by peptide synthesis. Such modifications include, for example, deletions, and / or insertions, and / or substitutions of residues within the amino acid sequence of the anti-ILT4 antibody. Any combination of deletions, insertions, and substitutions may be performed to obtain the final construct, as long as the final construct possesses the desired characteristics, such as antigen binding properties.

[0407] Substitution, insertion, and deletion variants

[0408] In certain embodiments, antibody variants with one or more amino acid replacements are provided. The sites of interest for substitution mutagenesis include CDR and FR. Conservative replacements are shown under the heading of "preferred replacements" in Table 2. More substantial variations are provided under the heading of "exemplary replacements" in Table 2, and are further described below with reference to amino acid side chain classes. Amino acid replacements can be introduced into the antibody of interest, and the product is screened for desired activity, such as retained / improved antigen binding, reduced immunogenicity, or improved ADCC or CDC.

[0409] Table 2. Amino acid substitutions

[0410] Based on common side chain properties, amino acids can be grouped as follows:

[0411] (1) Hydrophobic: norleucine, Met, Ala, Val, Leu, Ile;

[0412] (2) Neutral, hydrophilic: Cys, Ser, Thr, Asn, Gln;

[0413] (3) Acidic: Asp, Glu;

[0414] (4) Basic: His, Lys, Arg;

[0415] (5) Residues that affect chain orientation: Gly, Pro;

[0416] (6) Aromatic: Trp, Tyr, Phe.

[0417] Non-conservative substitutions will entail exchanging a member of one of these classes for a member of another class.

[0418] A class of substitution variants involves replacing one or more CDR residues of a parent antibody (e.g., humanized or human antibody). Generally, the variants selected for further study will have changes (e.g., improvements) in certain biological properties (e.g., increased affinity, reduced immunogenicity) relative to the parent antibody, and / or will substantially retain certain biological properties of the parent antibody. An exemplary substitution variant is an affinity-matured antibody, which can be readily produced using, for example, affinity maturation techniques based on phage display (e.g., those described herein). In short, one or more CDR residues are mutated, and the variant antibody is displayed on phage, and screened for specific biological activity (e.g., binding affinity). Changes (e.g., substitutions) can be made to CDR, for example, to improve antibody affinity. Such changes can be made to CDR "hot spots," i.e., residues encoded by codons that undergo mutations at high frequency during the somatic maturation process, and / or residues contacting antigens, while binding affinity is tested for the variant VH or VL obtained. In some embodiments of affinity maturation, diversity is introduced into the variable gene selected for maturation by any of a variety of methods (e.g., fallibility PCR, chain shuffling, or oligonucleotide-guided mutagenesis). Then, a secondary library is created. The library is then screened to identify any antibody variant with desired affinity. Another method of introducing diversity relates to a CDR-directed method, in which several CDR residues (e.g., 4-6 residues at a time) are randomized. CDR residues that specifically identify antigen binding can be, for example, identified using alanine scanning mutagenesis or modeling. In particular, HCDR3 and LCDR3 are often targeted.

[0419] In certain embodiments, substitution, insertion or deletion can occur in one or more CDRs, as long as such changes do not substantially reduce the ability of the antibody to bind to antigen. For example, conservative changes (e.g., conservative substitutions, as provided herein) can be made to the CDRs, which do not substantially reduce binding affinity. Such changes can be, for example, outside the antigen contact residues in the CDRs. In certain embodiments of the variant VH and VL sequences provided above, each CDR is unchanged, or contains no more than 1, 2 or 3 amino acid substitutions.

[0420] A method that can be used to identify residues or regions that can be used as mutagenesis targets in antibodies is called "alanine scanning mutagenesis". In this method, a residue or target residue group (e.g., charged residues, such as Arg, Asp, His, Lys, and Glu) is identified and replaced with neutral or negatively charged amino acids (e.g., Ala or polyalanine) to determine whether the interaction of the antibody with the antigen is affected. Further substitutions can be introduced at amino acid positions that show functional sensitivity to the initial substitution. In addition, the contact points between the antibody and the antigen can be identified by studying the crystal structure of the antigen-antibody complex. These contact residues and adjacent residues can be targeted or eliminated as substitution candidates. Variants can be screened to determine whether they contain desired properties.

[0421] Amino acid sequence insertions include amino and / or carboxyl terminal fusions ranging in length from 1 residue to polypeptides containing 100 or more residues, and intrasequence insertions of single or multiple amino acid residues. Examples of terminal insertions include antibodies with an N-terminal methionyl residue. Other insertion variants of antibody molecules include fusions of the N- or C-terminus of an antibody with an enzyme or a polypeptide that extends the serum half-life of the antibody.

[0422] Recombination methods

[0423] Anti-ILT4 antibodies can be produced using recombinant methods.For these methods, one or more isolated nucleic acids encoding the anti-ILT4 antibodies are provided.

[0424] In one embodiment, the present disclosure provides an isolated nucleic acid encoding an anti-ILT4 antibody as described above. Such nucleic acids can be given to independently encode any of the aforementioned polypeptide chains. In another aspect, the present disclosure provides one or more vectors (e.g., expression vectors) comprising such nucleic acids. In another aspect, the present disclosure provides a host cell comprising such nucleic acids. In one embodiment, a method for preparing a polypeptide is provided, wherein the method comprises culturing a host cell comprising a nucleic acid encoding the polypeptide, as provided above, under conditions suitable for expression, and optionally recovering the anti-ILT4 antibody from the host cell (or host cell culture medium).

[0425] In order to recombinantly produce an anti-ILT4 antibody, the nucleic acid encoding the protein is isolated and inserted into one or more vectors for further cloning and / or expression in a host cell. Such nucleic acids can be easily isolated and sequenced using conventional procedures, or produced by recombinant methods or obtained by chemical synthesis.

[0426] Suitable host cells for cloning or expressing vectors encoding anti-ILT4 antibodies include prokaryotic or eukaryotic cells described herein. For example, they can be produced in bacteria, particularly when glycosylation and Fc effector functions are not required. After expression, the soluble fraction can be separated from the bacterial cell paste and further purified.

[0427] In addition to prokaryotes, eukaryotic microorganisms such as filamentous fungi or yeast are also suitable cloning or expression hosts for protein-encoding vectors, including fungal and yeast strains. Suitable host cells suitable for expressing proteins can also be derived from multicellular organisms (invertebrates and vertebrates); Examples of invertebrate cells include plant and insect cells. Many baculovirus strains have been identified that can be used in conjunction with insect cells, particularly for transfection of Spodoptera frugiperda cells; plant cell cultures can also be used as hosts, for example, US5959177, US6040498, US6420548, US7125978 and US6417429; vertebrate cells can also be used as hosts, for example, mammalian cell lines adapted to growth in suspension. Other examples of suitable mammalian host cell lines are monkey kidney CV1 line transformed by SV40 (COS-7); human embryonic kidney line (293 or 293T cells); baby hamster kidney cells (BHK); mouse Sertoli cells (TM4 cells); monkey kidney cells (CV1); African green monkey kidney cells (VERO-76); human cervical carcinoma cells (HELA); canine kidney cells (MDCK); buffalo rat liver cells (BRL3A); human lung cells (W138); human liver cells (Hep G2); mouse mammary tumor (MMT 060562); TRI cells; MRC 5 cells; and FS4 cells. Other suitable mammalian host cell lines include Chinese hamster ovary (CHO) cells, including DHFR-CHO cells; and myeloma cell lines such as Y0, NS0, and Sp2 / 0. For review of certain mammalian host cell lines suitable for antibody production, see, e.g., Yazaki, P. and Wu, AM, Methods in Molecular Biology, Vol. 248, Lo, BKC (ed.), Humana Press, Totowa, NJ (2004), pp. 255-268.

[0428] Determination

[0429] The anti-ILT4 antibodies provided herein can be identified, screened or characterized by various assays known in the art for their physical / chemical characteristics and / or biological activity. In one aspect, the activity of the anti-ILT4 antibodies of the present disclosure can be tested, for example, by known methods such as ELISA, Western blotting, etc.

[0430] Treatment methods and administration routes

[0431] Any anti-ILT4 antibody provided herein can be used in a method of treatment. In another aspect, the present disclosure provides a use of an anti-ILT4 antibody in the manufacture or preparation of a medicament. In some embodiments, the disease is a disease or condition associated with ILT4. In some embodiments, the disease is selected from astrocytoma (e.g., anaplastic astrocytoma), glioblastoma, bladder cancer, bone cancer, brain cancer, breast cancer (e.g., breast cancer characterized by BRCA1 and / or BRCA2 mutations), carcinoid tumor, cervical cancer, choroid plexus papilloma, colorectal cancer (e.g., colon cancer and rectal cancer), fallopian tube cancer, ependymoma, gallbladder cancer, gastric cancer, head and neck cancer, idiopathic myelofibrosis, kidney cancer or renal cell carcinoma (e.g., renal rhabdoid tumor, Wilms tumor), renal pelvis tumor, leukemia, liver cancer (e.g., hepatocellular carcinoma), esophageal cancer (e.g., also known as "esophageal cancer", esophageal squamous cell carcinoma), lung cancer (e.g., non-small cell lung cancer and small cell lung cancer), lymphoma, medulloblastoma, melanoma, meningioma, Merkel cell carcinoma, interstitial cell carcinoma, In some embodiments, the disease is selected from the group consisting of ovarian cancer, lung cancer, esophageal squamous cell carcinoma, colorectal cancer, renal cell carcinoma, or melanoma.

[0432] In yet another aspect, a pharmaceutical composition comprising the anti-ILT4 antibody is provided, for example, for use in any of the above pharmaceutical uses or treatment methods. In one embodiment, the pharmaceutical composition comprises any of the anti-ILT4 antibodies provided herein and a pharmaceutically acceptable carrier. In another embodiment, the pharmaceutical composition further comprises at least one additional therapeutic agent.

[0433] The anti-ILT4 antibodies of the present disclosure can be used alone or in combination with other agents for treatment. For example, the antibodies of the present disclosure can be co-administered with at least one additional therapeutic agent.

[0434] The anti-ILT4 antibodies (and any additional therapeutic agents) disclosed herein can be administered by any suitable means, including parenteral, intrapulmonary and intranasal, and if local treatment is required, intralesional administration. Parenteral infusion includes intramuscular, intravenous, intraarterial, intraperitoneal or subcutaneous administration. Administration can be by any appropriate route, for example, by injection, such as intravenous or subcutaneous injection, which depends in part on whether the administration is short-term or long-term. Various dosing schedules are contemplated herein, including but not limited to, single or multiple administrations at multiple time points, push administration and pulse infusion.

[0435] The anti-ILT4 antibodies disclosed herein will be formulated, dosed, and applied in a manner consistent with good medical practice. Factors considered in this context include the specific condition being treated, the specific mammal being treated, the clinical condition of the individual patient, the cause of the condition, the delivery site of the agent, the method of administration, the administration time arrangement, and other factors known to medical practitioners. The anti-ILT4 antibodies may be formulated with or without one or more agents currently used to prevent or treat the condition. The effective amount of such other agents depends on the amount present in the pharmaceutical composition, the type of condition or treatment, and other factors. These are typically used with the same dosage and administration route as described herein, or with about 1 to 99% of the dosage described herein, or with other dosages, and are used by any route determined to be suitable through experience / clinical testing.

[0436] For the prevention or treatment of disease, the appropriate dosage of the anti-ILT4 antibodies of the present disclosure (when used alone or in combination with one or more other additional therapeutic agents) will depend on the type of disease to be treated, the type of therapeutic molecule, the severity and course of the disease, whether it is administered for preventive or therapeutic purposes, previous treatments, the patient's clinical history and response to the therapeutic molecule, and the judgment of the attending physician. The therapeutic molecule is appropriately administered to the patient at one time or over a series of treatments.

[0437] Products

[0438] In another aspect of the present disclosure, an article of manufacture (as an example, the article of manufacture is prepared in the form of a kit) is provided, which contains materials that can be used to treat, prevent and / or diagnose the above-mentioned conditions. The article of manufacture comprises a container and a label or package insert on or associated with the container. Suitable containers include, for example, bottles, vials, syringes, IV solution bags, etc. The container can be formed from various materials such as glass or plastic. The container contains a composition that is effective for treating, preventing and / or diagnosing the condition alone or in combination with another composition, and may have a sterile access port (for example, the container can be an intravenous solution bag or vial with a stopper pierceable by a hypodermic needle). At least one active agent in the composition is an anti-ILT4 antibody of the present disclosure. The label or package insert indicates that the composition is used to treat the selected condition. In addition, the article of manufacture may comprise: (a) a first container containing a composition, wherein the composition contains an anti-ILT4 antibody of the present disclosure; and (b) a second container containing a composition, wherein the composition contains an additional cytotoxic agent or other therapeutic agent. The article of manufacture in this embodiment of the present disclosure may further comprise a package insert indicating that the composition can be used to treat a specific condition. Alternatively, or additionally, the article of manufacture may further comprise a second (or third) container comprising a pharmaceutically acceptable buffer. From a commercial and user perspective, it may further comprise other materials required, including other buffers, diluents, filters, needles, and syringes.

[0439] Example

[0440] The present disclosure is further described below with reference to the following examples and test cases, but these examples and test cases are not intended to limit the scope of this disclosure. Experimental methods in the examples and test cases disclosed herein, where specific conditions are not specified, generally follow conventional conditions, such as those in the Cold Spring Harbor Laboratory Manual of Antibody Techniques and the Molecular Cloning Manual, or the conditions recommended by the raw material or product manufacturer. Reagents whose sources are not specified are commercially available reagents.

[0441] Example 1: Preparation of ILT4 antigen

[0442] Using UniProt LIRB2_HUMAN (human LILRB2 protein, UniProt ID: Q8N423) as a template for ILT4, the amino acid sequences of the antigens and detection proteins used in this disclosure were designed. Optionally, different tags, such as a His tag or Fc tag, were fused to the ILT4 protein. These proteins were cloned into the pTT5 vector (Biovector, CAT#102762), transiently expressed in 293 cells, and purified to obtain the antigens used for immunization and detection in this disclosure.

[0443] 1. ILT4-Fc, the extracellular domain of ILT4 protein tagged with Human-IgG1-Fc, is used as the antigen for immunization.

[0444] Note: The italicized ones are the extracellular domains, and the single underlined ones are Human-IgG1-Fc.

[0445] 2. The extracellular domain of ILT4 protein with a His tag: ILT4-His, is used as the detection antigen.

[0446] Note: The italic part is the extracellular domain, and the single underline part is the His tag part.

[0447] CHO-S cells overexpressing the full-length ILT4 protein (CHO-S / ILT4) were used as test cells.

[0448] Note: Single underline indicates signal peptide, italics indicates extracellular domain, dotted underline indicates transmembrane domain, and double underline indicates intracellular domain.

[0449] Example 2: Purification of ILT4-related recombinant proteins

[0450] 1. Purification of His-tagged recombinant proteins

[0451] The cell expression supernatant sample was centrifuged at high speed to remove impurities, and the buffer was replaced with PBS, and imidazole was added to a final concentration of 5mM. The nickel column was balanced with a PBS solution containing 5mM imidazole and rinsed 2-5 times the column volume. The replaced cell supernatant sample was loaded onto a Ni Sepharose excel column (GE, 17-3712-02). The column was rinsed with a PBS solution containing 5mM imidazole to a final concentration of 5mM. 280 The reading dropped to the baseline. The chromatography column was then rinsed with PBS + 10mM imidazole to remove non-specifically bound impurities and collect the effluent. The target protein was then eluted with a PBS solution containing 300mM imidazole, and the elution peak was collected. The collected eluate was concentrated and further purified using gel chromatography Superdex200 (GE, 28-9893-35) with PBS as the mobile phase. The aggregate peak was removed and the elution peak was collected. The obtained protein was identified as correct by electrophoresis, peptide mapping, and LC-MS and then allocated for use. ILT4-His with a His tag was obtained and used as an antigen for detection of the antibody disclosed herein.

[0452] 2. Purification of Fc-tagged recombinant proteins or antibodies

[0453] The cell expression supernatant sample was centrifuged at high speed to remove impurities, and the supernatant was subjected to MabSelect Sure (GE, 17-5438-01) affinity chromatography. The MabSelect Sure chromatography column was first regenerated with 0.2M NaOH, rinsed with pure water, and then equilibrated with PBS. After the supernatant was combined, the column was rinsed with PBS to A 280 The reading dropped to baseline. The target protein was eluted with 0.1M acetate buffer at pH 3.5 and neutralized with 1M Tris-HCl. The eluted sample was appropriately concentrated and further purified using a PBS-equilibrated gel chromatography Superdex200 (GE, 28-9893-35). The target protein was collected in the receiving tube and concentrated to an appropriate concentration. This method was used to purify the ILT4-Fc fusion protein and can also be used to purify the humanized antibody proteins involved in this disclosure.

[0454] Example 3: Acquisition of anti-human ILT4 antibodies

[0455] 1. Mouse Immunization

[0456] Anti-human ILT4 monoclonal antibodies were produced by immunizing mice. Female SJL white mice, 6-8 weeks old (Shanghai Slake Laboratory Animal Co., Ltd., Animal Production License No. SCXK(Shanghai)2017-0005) were used in this experiment. Mice were housed in an SPF-grade laboratory environment for one week under a 12 / 12 hour light / dark cycle, a temperature of 20-25°C, and a humidity of 40-60%. Acclimated mice were immunized according to the following protocol.

[0457] Mice were immunized with ILT4-Fc protein. Gold Adjuvant (Sigma Cat No.T2684) and Thermo Alum (Thermo Cat No.77161) adjuvant cross immunization. Antigen and adjuvant ( Gold Adjuvant) ratio was 1:1, antigen and adjuvant (Thermo The ratio of immunization dose to dose of 50 μg / mouse / dose (primary immunization) and 25 μg / mouse / dose (boost immunization) was 3:1. Immunizations were performed on days 0, 14, and 34 after antigen emulsification. Blood samples were collected on days 25 and 41 to determine antibody titers in mouse serum. After the third immunization, mice with high serum antibody titers that plateaued were selected for single B cell screening. Three days prior to screening, a booster immunization was performed with an intraperitoneal (ip) injection of 25 μg / mouse of an antigen solution in saline.

[0458] 2. Single B Cell Screening

[0459] Single B cells were screened primarily through positive and negative screening, using 10*genomics and bioinformatics techniques to generate a series of antibody variable region sequences. The resulting sequences were subjected to CDR classification, and the mouse variable region sequences were selected for ligation with human antibody constant region sequences to express chimeric antibodies. Antibody sequences that specifically bind to ILT4 were selected through methods such as binding to the ILT4 protein, cell binding, and ILT4 / HLA-G blocking. The heavy and light chain variable region sequences of the resulting antibodies are as follows:

[0460] Note: Single underline: variable region; Double underline: CDR; CDR is numbered according to Kabat.

[0461] The heavy chain and light chain CDR region sequences of the murine antibody are shown in Table 3 below.

[0462] Table 3. Antibody heavy chain and light chain CDR sequences

[0463] 3. Phage Library Screening

[0464] Since the screening goal is to obtain antibody sequences that only bind to ILT4, a combination of reverse screening and positive screening is used. First, phages that can bind to biotin-labeled human ILT2 are removed from the phage library (reverse screening), and then phages that can bind to biotin-labeled human ILT4 are screened from the remaining phages (positive screening). The specific process is as follows: the phage library (5*10 12 / pfu) were suspended in 1 mL of PBS containing skim milk powder (BD, 232100), and 2 μg / mL biotin-labeled human ILT2-His protein was added for flipping and incubation, followed by the addition of 100 μL M-280 Streptavidin (Thermofisher, 11206D) was incubated. The tube was placed on a magnetic stand for 30 seconds, the supernatant was removed, 2 μg / mL biotin-labeled human ILT4-His protein was added and continued to incubate with flipping, followed by the addition of 100 μL Dynabeads for incubation. The tube was placed on a magnetic stand for 30 seconds to remove the supernatant, the Dynabeads were washed several times with 1 mL of PBS containing Tween-20, and then 0.5 mL of trypsin (Sigma, T1426-250MG) was added for elution. The eluted phage was infected with Escherichia coli SS320, the titer was determined, and the phage was amplified and concentrated for the next round of panning. Three rounds of screening were performed according to this method, and the monoclonal clones obtained from the screening were inoculated into 96-well plates (Sangon Biotech, F600582-0001) to package the phage. ELISA was used to detect phage that could bind to human ILT4 protein but not human ILT2 protein, and the corresponding monoclonal was sequenced and analyzed. The variable region sequence of the antibody was finally obtained as follows:

[0465] Note: Single underline: variable region; Double underline: CDR; CDR is numbered according to Kabat.

[0466] The heavy and light chain CDR region sequences of the fully human antibody are shown in Table 4 below.

[0467] Table 4. Antibody heavy chain and light chain CDR sequences

[0468] 4. Construction of Chimeric Antibodies

[0469] Primers were designed for PCR to obtain the VH / VK gene fragments of each mouse antibody, which were then homologously recombined with the expression vector pTT5 (with signal peptide and constant region gene (CH1-FC / CL) fragments, constructed in the laboratory) to construct the full-length antibody expression vector VH-CH1-FC-pTT5 / VK-CL-pTT5, expressing the anti-human ILT4 chimeric antibody in the form of IgG4 (LALA). Chimeric antibodies were obtained by combining the variable region sequences of the murine anti-ILT4 antibodies ChP1-C4, ChP1-B4, ChP1-D10, ChP2-C7, ChP1-G7, ChP1-B9, ChP2-C6, ChP1-F7, ChP2-E8, ChP2-E3, ChP2-C10, ChP2-F4, ChP2-F10, ChP2-C4, ChP2-G9, ChP2-B3, ChP2-E7, ChP2-G4, ChP2-E11, ChP1-D7, ChP1-E11, ChP2-B9, ChP2-C2, and ChP2-E10 with the constant regions shown in SEQ ID NO: 171 and SEQ ID NO: 172. Exemplarily, ChP1-C4 represents a chimeric antibody comprising the murine heavy chain variable region, light chain variable region, and the constant region of MP1-C4. The sequences of the heavy chain and light chain constant regions of the chimeric antibody are as follows:

[0470] Note: Single underline: CH1; Dot underline: Hinge; Double underline: Fc.

[0471] Example 4: Humanization of anti-human ILT4 mouse antibody

[0472] By comparing the IMGT human antibody heavy and light chain variable region germline gene database and MOE software, we selected heavy and light chain variable region germline genes with high homology to MP2-E3, MP2-G9, MP2-E8, MP1-G7, MP2-C6, and MP1-D7 as templates. The CDRs of these six murine antibodies were transplanted into the corresponding human templates, forming a variable region sequence with the order FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4. Amino acid residues were identified and annotated using the Kabat numbering system.

[0473] 1. Humanization of MP2-E3

[0474] For the humanization of the MP2-E3 antibody, IGKV1-39*01 was used as the light chain framework template, and IGHV1-3*01 was used as the heavy chain framework template. The CDR regions of the mouse antibody were transplanted onto the selected humanized templates. Using MOE software, buried residues, residues directly interacting with the CDR regions, and sites with high-risk hotspots and immunogenicity risks were identified for backmutation and point mutation. Different light and heavy chain variable regions of the humanized antibodies were designed.

[0475] Table 5. Specific framework substitutions and amino acid substitutions in humanized antibody P2-E3

[0476] Note: Amino acid numbering follows the Kabat numbering system. I48V means that the I at position 48 is mutated to V according to the Kabat numbering system, and so on.

[0477] Table 6. CDRs of humanized antibody P2-E3

[0478] The variable region sequence of the humanized antibody P2-E3 is as follows:

[0479] Note: Single underline: variable region; Double underline: CDR; CDR is numbered according to Kabat.

[0480] Table 7. Humanized antibodies of the P2-E3 series

[0481] 2. Humanization of MP2-G9

[0482] For the humanization of the MP2-G9 antibody, IGKV1-39*01 was used as the light chain framework template, and IGHV4-31*01 was used as the heavy chain framework template. The CDR regions of the mouse antibody were transplanted onto the selected humanized templates. Using MOE software, buried residues, residues directly interacting with the CDR regions, and sites with high-risk hotspots and immunogenicity risks were identified for backmutation and point mutation. Different light and heavy chain variable regions of the humanized antibodies were designed.

[0483] Table 8. Specific framework substitutions and amino acid substitutions of humanized antibody P2-G9

[0484] Note: Amino acid numbering follows the Kabat numbering system.

[0485] The variable region sequence of the humanized antibody P2-G9 is as follows:

[0486] Note: Single underline: variable region; Double underline: CDR; CDR is numbered according to Kabat.

[0487] Table 9-1. Humanized antibodies of the P2-G9 series

[0488] Table 9-2. CDR sequences of huP2-G9 antibody (according to Kabat numbering convention)

[0489] Table 9-3. CDR sequences of huP2-G9 antibody (according to IMGT numbering rules)

[0490] Table 9-4. CDR sequences of huP2-G9 antibody (according to Chothia numbering convention)

[0491] 3. Humanization of MP2-E8

[0492] For the humanization of the MP2-E8 antibody, IGKV1-33*01 was used as the light chain framework template, and IGHV3-21*01 was used as the heavy chain framework template. The CDR regions of the mouse antibody were transplanted onto the selected humanized templates. Using MOE software, buried residues, residues directly interacting with the CDR regions, and sites with high-risk hotspots and immunogenicity risks were identified for backmutation and point mutation. Different light and heavy chain variable regions of the humanized antibodies were designed.

[0493] Table 10. Specific framework substitutions and amino acid substitutions of humanized antibody P2-E8

[0494] Note: Amino acid numbering follows the Kabat numbering system.

[0495] Table 11. CDRs of humanized antibody P2-E8

[0496] The variable region sequence of the humanized antibody P2-E8 is as follows:

[0497] Note: Single underline: variable region; Double underline: CDR; CDR is numbered according to Kabat.

[0498] Table 12. Humanized antibodies of the P2-E8 series

[0499] 4. Humanization of MP1-G7

[0500] For the humanization of the MP1-G7 antibody, IGKV1-39*01 was used as the light chain framework template, and IGHV4-31*02 was used as the heavy chain framework template. The CDR regions of the mouse antibody were transplanted onto the selected humanized templates. Using MOE software, buried residues, residues directly interacting with the CDR regions, and sites with high-risk hotspots and immunogenicity risks were identified for backmutation and point mutation. Different light and heavy chain variable regions of the humanized antibodies were designed.

[0501] Table 13. Specific framework substitutions and amino acid substitutions of humanized antibody P1-G7

[0502] Note: Amino acid numbering follows the Kabat numbering system.

[0503] The variable region sequence of the humanized antibody P1-G7 is as follows:

[0504] Note: Single underline: variable region; Double underline: CDR; CDR is numbered according to Kabat.

[0505] Table 14. Humanized antibodies of the P1-G7 series

[0506] 5. Humanization of MP2-C6

[0507] For the humanization of the P2-C6 antibody, IGKV4-1*01 and IGKV3-11*01 were used as templates for the light chain framework region, and IGHV1-18*01 was used as template for the heavy chain framework region. The CDR regions of the mouse antibody were transplanted onto the selected humanized templates. Using MOE software, buried residues, residues directly interacting with the CDR regions, and sites with high-risk hotspots and immunogenicity risks were identified for backmutation and point mutation. Different light and heavy chain variable regions of the humanized antibodies were designed.

[0508] Table 15. Specific framework substitutions and amino acid substitutions of humanized antibody P2-C6

[0509] Note: Amino acid numbering follows the Kabat numbering system.

[0510] Table 16. CDRs of humanized antibody P2-C6

[0511] The variable region sequence of the humanized antibody P2-C6 is as follows:

[0512] Note: Single underline: variable region; Double underline: CDR; CDR is numbered according to Kabat.

[0513] Table 17-1. Humanized antibodies of the P2-C6 series

[0514] Table 17-2. CDR sequences of huP2-C6 antibody (according to Kabat numbering convention)

[0515] Table 17-3. CDR sequences of huP2-C6 antibody (according to IMGT numbering rules)

[0516] Table 17-4. CDR sequences of huP2-C6 antibody (according to Chothia numbering convention)

[0517] 6. Humanization of MP1-D7

[0518] For the humanization of the MP1-D7 antibody, IGKV4-1*01 and IGKV2-28*01 were used as templates for the light chain framework region, and IGHV1-18*01 was used as a template for the heavy chain framework region. The CDR regions of the mouse antibody were transplanted onto the selected humanized templates. Using MOE software, buried residues, residues directly interacting with the CDR regions, and sites with high-risk hotspots and immunogenicity risks were identified for backmutation and point mutation. Different light and heavy chain variable regions of the humanized antibodies were designed.

[0519] Table 18. Specific framework substitutions and amino acid substitutions of humanized antibody P1-D7

[0520] Note: Amino acid numbering follows the Kabat numbering system.

[0521] Table 19. CDRs of humanized antibody P1-D7

[0522] The variable region sequence of the humanized antibody P1-D7 is as follows:

[0523] Note: Single underline: variable region; Double underline: CDR; CDR is numbered according to Kabat.

[0524] Table 20. Humanized antibodies of the P1-D7 series

[0525] 7. Modification of the fully human antibody P2

[0526] Based on the high-risk hotspot, VL selected the N30Q point mutation; based on the site of immunogenicity risk, VL selected the T76S and A81E point mutations.

[0527] Table 21. CDRs of fully human antibody P2

[0528] Note: Single underline: variable region; Double underline: CDR; CDR is numbered according to Kabat.

[0529] 8. Construction and Expression of the Complete Humanized Antibody Against Human ILT4

[0530] Primers were designed for PCR to construct the VH / VK gene segments of each humanized antibody. These segments were then homologously recombined with the expression vector pTT5 (containing a signal peptide and constant region gene (CH1-FC / CL) fragments, constructed in the laboratory) to construct the full-length antibody expression vector VH-CH1-Fc-pTT5 / VK-CL-pTT5. Using SPR and FACS analysis combined with ILT4, the heavy and light chain sequences of the humanized antibodies huP2-E3, huP2-G9, huP2-E8, huP1-G7, huP2-C6, huP1-D7, and the fully human antibody P2m were determined as follows:

[0531] huP2-E3 humanized antibody:

[0532] huP2-G9 humanized antibody:

[0533] huP2-E8 humanized antibody:

[0534] huP1-G7 humanized antibody:

[0535] huP2-C6 humanized antibody:

[0536] huP1-D7 humanized antibody:

[0537] P2m fully human antibody:

[0538] Note: The single-lined portion is the variable region, and the unlined portion is the hIgG1 (LALA), hIgG4 (LALA) and CL constant region.

[0539] The sequences of the heavy chain constant region and light chain constant region of the humanized antibody are as follows:

[0540] Note: Single underline: CH1; Dot underline: Hinge; Double underline: Fc.

[0541] Note: Single underline: CH1; Dot underline: Hinge; Double underline: Fc.

[0542] The positive control molecules used in this disclosure are MK and JTX.

[0543] MK sequence source: WO2018187518A1

[0544] The theoretical light and heavy chain amino acid sequences of MK are as follows (single underline: variable region; double underline: CDR; dotted underline: constant region):

[0545] JTX sequence source: WO2019126514A2

[0546] The theoretical amino acid sequences of the light and heavy chains of JTX are as follows (single underline: variable region; double underline: CDR; dotted underline: constant region):

[0547] Cells overexpressing HLA-G

[0548] Note: Single underline indicates signal peptide, italics indicates extracellular domain, dotted underline indicates transmembrane domain, and double underline indicates intracellular domain.

[0549] Example 5: ELISA detection of protein binding of anti-ILT4 antibodies

[0550] Human ILT4-His protein was diluted to 1 μg / mL in PBS and coated onto 96-well plates (Corning, CLS3590-100EA). The plates were then washed and blocked with 1% BSA at 37°C for 1 hour. After washing, various concentrations of anti-ILT4 antibody were added and incubated at 37°C for 1 hour. After washing, HRP-goat anti-human F(ab')2 secondary antibody (Jackson, 109-036-097) was added and incubated at 37°C for 1 hour. After washing, TMB chromogenic substrate (KPL, 52-00-03) was added and incubated at room temperature for 5-10 minutes. The reaction was terminated with 1 M H2SO4 and the absorbance was read at 450 nm using a VERSAmax microplate reader (Molecular Devices). The results are shown in Table 22.

[0551] Table 22. Binding ability of anti-ILT4 antibodies to ILT4 protein

[0552] The experimental results showed that the anti-ILT4 chimeric antibodies had a higher binding ability to ILT4 protein than the control antibody JTX.

[0553] Example 6: Biacore detection of protein binding of anti-ILT4 antibodies

[0554] The affinity of the disclosed humanized antibodies for the ILT4-His protein was tested using Biacore. The antibodies were affinity-captured using a Protein A biosensor chip (Cytiva, 29127556). ILT4-His was then passed over the chip surface, and the reaction signal was monitored in real time to obtain binding and dissociation curves. After each experimental cycle, the biosensor chip was washed and regenerated with 10 mM Glycine-HCl, pH 1.5 (Cytiva, BR-1003-54). A 1:1 model was used for data fitting. The binding and dissociation characteristics of each antibody are shown in Table 23.

[0555] Table 23. Affinity of anti-ILT4 antibodies binding to ILT4 protein

[0556] The experimental results show that the humanized and fully human antibodies disclosed herein have a higher binding ability to the ILT4 protein than the control antibody.

[0557] Example 7: FACS detection of cell binding of anti-ILT4 antibodies

[0558] The affinity of the disclosed humanized antibody to CHO-S / ILT4 cells was tested by FACS. 6 After blocking CHO-S / ILT4 cells with 1% BSA, cells were incubated with various concentrations of anti-ILT4 antibody at 4°C for 1 hour. After washing twice with 1% BSA, cells were incubated with F(ab')2-goat anti-human IgG Fc secondary antibody, PE (Invitrogen, H10104), and incubated at 4°C for 0.5 hour. After washing twice with 1% BSA, fluorescence signals were measured using FACS. Results are shown in Table 24.

[0559] Table 24. Binding ability of anti-ILT4 antibodies to ILT4 stably transfected cell lines

[0560] The experimental results show that the humanized and fully human antibodies disclosed herein have the same or stronger binding ability to ILT4-positive cells as the control antibodies.

[0561] Example 8: Anti-ILT4 antibodies do not bind to other members of the LILR family

[0562] Human ILT2-His (prepared in the same manner as ILT4-His in Examples 1 and 2, with an amino acid sequence as shown in SEQ ID NO: 245), ILT3-His (prepared in the same manner as ILT4-His in Examples 1 and 2, with an amino acid sequence as shown in SEQ ID NO: 246) and ILT3-His (prepared in the same manner as ILT4-His in Examples 1 and 2, with an amino acid sequence as shown in SEQ ID NO: 247) were added to the PBS. 246), ILT4-His (same method as in Examples 1 and 2), LILRB5-His (Acro, CDC-H5220), LILRA1-His (Acro, LI1-H82E8), LILRA2-His (Acro, LI2-H82E9), LILRA4-His (SinoBiological, 16058-H08H), LILRA5-His (Acro, LI5-H82E1), LILRA6-His (Acro, LI6-H82E2), or LILRA3-His (Acro, LI3-H82E0) were diluted to 1 μg / mL and coated on 96-well plates (Corning, CLS3590-100EA) and incubated overnight at 4°C. After washing, the plates were blocked with 1% BSA at 37°C for 1 hour. After washing, 10 μg / mL anti-ILT4 antibody was added and incubated at 37°C for 1 hour. After washing, HRP-goat anti-human F(ab′)2 secondary antibody (Jackson, 109-036-097) was added and incubated at 37°C for 1 hour. After washing, TMB chromogenic substrate (KPL, 52-00-03) was added and incubated at room temperature for 5-10 minutes. The reaction was terminated by adding 1 M H2SO4, and the absorbance was read at 450 nm using a VERSAmax microplate reader (Molecular Devices). The results are shown in Table 25.

[0563] ILT2 protein extracellular domain with His tag: ILT2-His

[0564] Note: The italic part is the extracellular domain, and the single underline part is the His tag part.

[0565] ILT3 protein extracellular domain with His tag: ILT3-His

[0566] Note: The italic part is the extracellular domain, and the single underline part is the His tag part.

[0567] Table 25. Binding ability of anti-ILT4 antibodies to LILR family member proteins

[0568] The experimental results show that the humanized and fully human antibodies disclosed herein do not bind to other members of the LILR family.

[0569] Example 9: Blocking effect of anti-ILT4 antibodies on the binding of ILT4 and HLA-G

[0570] The cell blocking activity of anti-ILT4 antibody was detected by flow cytometry. 6 CHO-S / ILT4 cells were blocked with 1% BSA. Anti-ILT4 antibodies and CF647-labeled HLA-G tetramers (novoprotein) diluted in 1% BSA were added at various concentrations and incubated at 4°C for 1 hour. The cells were centrifuged at 500g for 4 minutes, and the supernatant discarded. After washing twice with 1% BSA, fluorescence signals were measured using FACS.

[0571] Table 26. Blocking ability of anti-ILT4 antibodies on the binding of ILT4 and HLA-G

[0572] The experimental results show that the antibodies huP2-E3, huP2-G9, huP2-C6 and P2m disclosed herein can effectively block the binding of ILT4 to HLA-G, and the blocking activity is stronger than that of the control antibodies MK and JTX.

[0573] Example 10: Blocking effect of anti-ILT4 antibodies on ILT4 and its downstream signaling pathways

[0574] The ability of anti-ILT4 antibodies to block ILT4 was detected using the 3A9 / ILT4 reporter system. 1 μg / mL mCD3 antibody (BioLegend, 100238) was inoculated into a 96-well plate (Corning, 3599), incubated at 37°C for 2 hours, and the supernatant was discarded. 3A9 cells (ATCC, CRL-3293) overexpressing the full-length ILT4 protein were collected and resuspended in RPMI 1640 (Mei Lun, PWL004) + 5% FBS (Gibco, 10099-141) + 0.05mM 2-mercaptoethanol (Sigma, M3148-25mL) to adjust the density to 8.3*10 5 Cells were added to the 96-well plate. Anti-ILT4 antibodies at varying concentrations were added and incubated at 37°C, 5% CO₂ for 24 hours. Cell supernatants were collected after 24 hours. mIL-2 secretion was assayed using the mIL-2 kit (Xinbosheng, EMC002.96.2). Results are shown in Figures 1A-1D.

[0575] The experimental results showed that the antibodies disclosed herein can more effectively relieve the inhibitory effect of ILT4 than the control antibody MK, and promote 3A9 cells to secrete higher levels of mIL-2.

[0576] Example 11: Effect of anti-ILT4 antibodies on cytokine secretion by macrophages

[0577] CD14 was isolated from healthy human PBMC using CD14 MicroBeads (Miltenyi Biotec, 130-050-201). + Monocytes. Resuspend CD14 in RPMI 1640 (Mei Lun, PWL004) + 10% FBS (Gibco, 10099-141) + 50 ng / mL M-CSF (Peprotech, 300-25). + cells, adjust the cell density to 2*10 6 After 7 days of differentiation, macrophages were obtained. Resuspend the macrophages in RPMI 1640 + 10% FBS and adjust the density to 1*10 6 Cells were plated with 100 μg / mL of TNFα-binding protein (TNFα) and plated in 96-well plates (Jet, 3788). LPS (Sigma, L3024-5MG) and various concentrations of anti-ILT4 antibodies were added and incubated at 37°C, 5% CO₂ for 24 h. Cell supernatants were collected and TNFα levels were detected using HUMAN TNFα KIT (Uninvitro, 62HTNFAPEG). The results are shown in Figures 2A-2D.

[0578] The experimental results showed that the antibodies disclosed herein can more effectively promote the transformation of macrophages to the M1 phenotype and secrete higher levels of the pro-inflammatory cytokine TNF-α than the control antibody MK.

[0579] Example 12: Combined Effect of Anti-ILT4 Antibody and Anti-PD-1 Antibody in Allogeneic MLR

[0580] CD14 was isolated from healthy human PBMC using CD14 MicroBeads (Miltenyi Biotec, 130-050-201). + Monocytes. Resuspend CD14 in RPMI 1640 (Mei Lun, PWL004) + 10% FBS (Gibco, 10099-141) + 50 ng / mL M-CSF (Peprotech, 300-25). + cells, adjust the cell density to 2*10 6 After 7 days of differentiation, macrophages were obtained. Resuspend the macrophages in RPMI 1640 + 10% FBS and adjust the density to 2*10 5 / mL, and inoculated into 96-well plates (Jet, 3788).

[0581] Pan T cells were isolated from PBMC of another donor using T cell sorting kit (Miltenyi, 130-096-535), resuspended in RPMI 1640 + 10% FBS, and adjusted to a density of 2*10 6 Cells were plated at 400 μg / mL and added to the 96-well plate. Anti-ILT4 antibody and / or anti-PD-1 antibody (anti-PD-1 antibody Hu23-11.IgG4AA, prepared with reference to patent WO2020156509A1, sequence as follows) were added to a final concentration of 10 μg / mL and incubated at 37°C, 5% CO2 for 6 days. Cell supernatants were collected and IFNγ was detected using the HUMAN IFNγ KIT (Unionvi, 62HIFNGPEG). The results are shown in Figures 3A-3E.

[0582] Full-length sequence of anti-PD-1 antibody Hu23-11.IgG4AA:

[0583] Table 27. CDRs of anti-PD-1 antibody Hu23-11.IgG4AA

[0584] Variable region sequence of anti-PD-1 antibody Hu23-11.IgG4AA:

[0585] The experimental results show that the effect of the disclosed antibody in promoting INFγ release in combination with anti-PD-1 antibody in the MLR experiment is significantly better than the combination of positive antibody MK or JTX with anti-PD-1 antibody.

[0586] Example 13: Effect of anti-ILT4 antibodies on promoting dendritic cell activation

[0587] CD14 was isolated from healthy human PBMC using CD14 MicroBeads (Miltenyi Biotec, 130-050-201). + Monocytes: Resuspend CD14 in RPMI 1640 (Mei Lun, PWL004) + 10% FBS (Gibco, 10099-141) + 100 ng / mL GM-CSF (Peprotech, 300-03-100 μg) + 100 ng / mL IL-4 (R&D, 217-IL-010). + After 5-6 days of differentiation, dendritic cells were obtained. The density of dendritic cells was adjusted to 1*10 6Cells were plated in 96-well plates (Jet, 3788) at 400 μg / mL. IL-10 (R&D, 217-IL-010) was added to a final concentration of 10 ng / mL, and anti-ILT4 antibody was added to a final concentration of 10 μg / mL. The cells were incubated at 37°C, 5% CO₂ for 48 h. Cell supernatants were collected and assayed for CCL-2 (Xinbosheng, EHC.113.96.2) and IL-6 (Cisbio, 62HIL06PEG) using ELISA kits. The upregulation of each cytokine or chemokine is shown in Table 28.

[0588] Table 28. Ability of anti-ILT4 antibodies to induce dendritic cells to secrete proinflammatory cytokines and chemokines

[0589] The experimental results show that in the presence of IL-10 in an immunosuppressive environment, the humanized antibody huP2-G9 disclosed herein can still induce dendritic cells to secrete higher levels of pro-inflammatory cytokines or chemokines.

[0590] Example 14: Inhibitory effect of anti-ILT4 antibody on subcutaneous transplanted tumors in mice bearing human breast cancer MDA-MB-231 / HLA-G

[0591] HLA-G overexpressing MDA-MB-231 cells (ATCC, HTB-26) in the logarithmic growth phase: T cells: The mixture was inoculated subcutaneously on the right rib of mice (Vitolliva), 200 μL (containing 100 μL Matrigel) per mouse, 6-8 mice per group. The vehicle control group (Vehicle group) was not inoculated. The day of grouping was defined as day 0 of the experiment. The remaining PBMCs were stimulated but continued to be cultured. After 1 week, 5×10 6 200 μL of cells / mouse were intraperitoneally injected into tumor-bearing mice. Anti-ILT4 antibody was intraperitoneally injected twice weekly starting on day 0 at a dose of 20 mpk. Tumor volume was monitored and data were recorded twice weekly.

[0592] The tumor volume of each group of animals was expressed as mean ± standard deviation (Mean ± SEM) and graphed using Graphpad Prism 8 software. Two-way ANOVA was used for statistical analysis.

[0593] The formula for calculating tumor volume (V) is: V = 1 / 2 × a × b 2 Where a and b represent length and width respectively.

[0594] Relative tumor proliferation rate T / C (%) = (T-T0) / (C-C0) × 100%, where T and C are the tumor volumes of the treatment group and the control group at the end of the experiment; T0 and C0 are the tumor volumes at the beginning of the experiment.

[0595] Tumor inhibition rate TGI (%) = 1-T / C (%).

[0596] The tumor inhibition rates of each group are shown in Table 29 below.

[0597] Table 29. Tumor inhibition rate of each group relative to the negative antibody group Note: biw means twice a week, 3w means three weeks, and ip means intraperitoneal injection.

[0598] The experimental results showed that compared with the PBS solvent control group (Vehicle group), The tumor inhibition rates of negative antibody-20mpk, MK-20mpk and huP2-G9-20mpk groups were 33.0%, 46.2% and 47.9%, respectively; compared with the control group Compared with the negative antibody-20mpk group, the tumor inhibition rates of the MK-20mpk group and the huP2-G9-20mpk group were 19.6% and 22.2% on the 13th day, respectively. The efficacy of the huP2-G9 alone group was comparable to that of the positive MK alone group, and the TGI value was even higher.

[0599] Example 15: Inhibitory effect of anti-ILT4 antibodies on subcutaneous transplanted tumors in mice bearing MC38 / HLA-G double-transgenic ILT4-ILT5 colon cancer cells

[0600] Double transgenic mice of human ILT4-ILT5 genes were inoculated with a suspension of MC38 cells (Kebai Bio, CBP60825) overexpressing HLA-G (same as in Example 9) (5×10 5 100 μL of the solution was injected subcutaneously into the right rib of the mouse, and tumor cells were selected until they grew to a volume of about 80-100 mm. 3 After size analysis, the mice were randomly divided into groups of 8 per group. Anti-ILT4 and anti-PD-1 antibodies (prepared in-house, the amino acid sequences of the heavy and light chains of anti-PD-1 antibodies (αPD-1) are shown in SEQ ID NO: 258 and SEQ ID NO: 259, respectively) were intraperitoneally injected twice weekly at doses of 30 mpk and 0.3 mpk, respectively. Dosing was initiated the day after grouping, with the day designated as day 0. Tumor volume was monitored and data recorded twice weekly.

[0601] The tumor volume of each group of animals was expressed as mean ± standard deviation (Mean ± SEM) and graphed using Graphpad Prism 8 software. Two-way ANOVA was used for statistical analysis.

[0602] The formula for calculating tumor volume (V) is: V = 1 / 2 × a × b 2 Where a and b represent length and width respectively.

[0603] Relative tumor proliferation rate T / C (%) = (T-T0) / (C-C0) × 100%, where T and C are the tumor volumes of the treatment group and the control group at the end of the experiment; T0 and C0 are the tumor volumes at the beginning of the experiment.

[0604] Tumor inhibition rate TGI (%) = 1-T / C (%).

[0605] The tumor inhibition rates of each group are shown in Table 30 below.

[0606] Table 30. Tumor inhibition rate of each group relative to PBS group Note: biw means twice a week, 3w means three weeks, and ip means intraperitoneal injection.

[0607] The experimental results showed that compared with the control antibody MK, huP2-G9 and huP2-C6 were more effective when used alone, and the anti-PD-1 antibody was more effective when used alone. In addition, the combination of huP2-G9 or huP2-C6 was slightly more effective than the corresponding single-use group.

[0608] Although the above invention has been described in detail with the aid of the accompanying drawings and examples for clarity of understanding, the descriptions and examples should not be construed as limiting the scope of the disclosure. The disclosures of all patent and scientific literature cited herein are expressly incorporated by reference in their entirety.

Claims

1. An anti-ILT4 antibody comprising a heavy chain variable region and a light chain variable region, wherein: The heavy chain variable region comprises HCDR1, HCDR2 and HCDR3, and the light chain variable region comprises LCDR1, LCDR2 and LCDR3, wherein a. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 184 or 185, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 187 or 186; or the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 32, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 33; or b. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of any one of SEQ ID NOs: 211, 205, 206, 207, 208, 209 or 210, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of any one of SEQ ID NOs: 212, 213 or 214; or the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 in SEQ ID NO: 40, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 in SEQ ID NO: 41, respectively; or c. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of any one of SEQ ID NOs: 181, 176, 177, 178, 179 or 180, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 183 or 182; or the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 in SEQ ID NO: 28, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 in SEQ ID NO: 29, respectively; or d. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of any one of SEQ ID NOs: 193, 190, 191 or 192, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of any one of SEQ ID NOs: 194, 195 or 196; or The HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise SEQ ID NO: 10 and the light chain variable region LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 11, respectively; or e. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 163, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 225 or 164; or f. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 197 or 198, respectively, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 199 or 200, respectively; or the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 in SEQ ID NO: 36, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 in SEQ ID NO: 37, respectively; or g. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 of any one of SEQ ID NOs: 217, 218, 219, 220 or 221, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 of SEQ ID NO: 222 or 223; or the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 in SEQ ID NO: 42, respectively, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 in SEQ ID NO: 43, respectively; or h. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 34, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 35; or i. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 18, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 19; or j. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 20, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 21; or k. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 24, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 25; or 1. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 44, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 45; or m. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 46, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 47; or n. the heavy chain variable region HCDR1, HCDR2 and HCDR3 respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 48, and the light chain variable region LCDR1, LCDR2 and LCDR3 respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 49; or o. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 50, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 51; Preferably, a. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 184, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 187; or b. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 211, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 212; or c. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 181, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 183; or d. The HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 193, and the LCDR1, LCDR2 and LCDR3 comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3, respectively, in SEQ ID NO: 194; or e. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 163, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 225; or f. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 197, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 199; or g. the HCDR1, HCDR2, and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2, and HCDR3 in SEQ ID NO: 217, and the LCDR1, LCDR2, and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2, and LCDR3 in SEQ ID NO: 222; More preferably, a. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 184, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO: 187; or b. the HCDR1, HCDR2 and HCDR3 of the heavy chain variable region respectively comprise the amino acid sequences of HCDR1, HCDR2 and HCDR3 in SEQ ID NO: 211, and the LCDR1, LCDR2 and LCDR3 of the light chain variable region respectively comprise the amino acid sequences of LCDR1, LCDR2 and LCDR3 in SEQ ID NO:

212.

2. The anti-ILT4 antibody according to claim 1, wherein: a. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 120, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 121, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or b. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 135, HCDR2 comprises the amino acid sequence of any one of SEQ ID NOs: 203, 136, 201, 202 or 204, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 137, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 138, LCDR2 comprises the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140; or c. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 111, HCDR2 comprises the amino acid sequence of any one of SEQ ID NOs: 173, 112, 174 or 175, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 113, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 115, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 116; or d. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 69, HCDR2 comprises the amino acid sequence of any one of SEQ ID NOs: 189, 70 or 188, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 71, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 72; or e. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 165, HCDR2 comprises the amino acid sequence of SEQ ID NO: 166, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 167, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 224 or 168, LCDR2 comprises the amino acid sequence of SEQ ID NO: 169, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 170; or f. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 125, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 126, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 127, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 128; or g. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 141, HCDR2 comprises the amino acid sequence of SEQ ID NO: 215 or 142, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 216 or 143, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 144, LCDR2 comprises the amino acid sequence of SEQ ID NO: 145, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 146; or h. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 99, HCDR2 comprises the amino acid sequence of SEQ ID NO: 122, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 123, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 124; or i. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 73, HCDR2 comprises the amino acid sequence of SEQ ID NO: 87, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 88, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 89, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 90; or j. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 91, HCDR2 comprises the amino acid sequence of SEQ ID NO: 92, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 93, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 85, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 94; or k. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 99, HCDR2 comprises the amino acid sequence of SEQ ID NO: 100, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 101, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 102, LCDR2 comprises the amino acid sequence of SEQ ID NO: 103, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 104; or 1. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 147, HCDR2 comprises the amino acid sequence of SEQ ID NO: 148, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 149, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 150, LCDR2 comprises the amino acid sequence of SEQ ID NO: 151, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 152; or m. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 153, HCDR2 comprises the amino acid sequence of SEQ ID NO: 154, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 155, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 133, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; or n. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 58, HCDR2 comprises the amino acid sequence of SEQ ID NO: 156, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 157, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 158, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 159; or o. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 160, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 161, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 162; Preferably, a. HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 120, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 121, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119 The amino acid sequence of b. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 135, HCDR2 comprises the amino acid sequence of SEQ ID NO: 203, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 137, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 138, LCDR2 comprises the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 140; or c. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 111, HCDR2 comprises the amino acid sequence of SEQ ID NO: 173, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 113, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 115, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 116; or d. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 69, HCDR2 comprises the amino acid sequence of SEQ ID NO: 189, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 71, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 61, LCDR2 comprises the amino acid sequence of SEQ ID NO: 62, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 72; or e. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 165, HCDR2 comprises the amino acid sequence of SEQ ID NO: 166, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 167, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 224, LCDR2 comprises the amino acid sequence of SEQ ID NO: 169, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 170; or f. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 105, HCDR2 comprises the amino acid sequence of SEQ ID NO: 125, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 126, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 127, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 128; or g. the heavy chain variable region HCDR1 comprises the amino acid sequence of SEQ ID NO: 141, HCDR2 comprises the amino acid sequence of SEQ ID NO: 215, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 216, and the light chain variable region LCDR1 comprises the amino acid sequence of SEQ ID NO: 144, LCDR2 comprises the amino acid sequence of SEQ ID NO: 145, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 146; More preferably, a. the HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 105, the HCDR2 comprises the amino acid sequence of SEQ ID NO: 120, and the HCDR3 comprises the amino acid sequence of SEQ ID NO: 121, and the LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 114, LCDR2 comprises the amino acid sequence of SEQ ID NO: 109, and LCDR3 comprises the amino acid sequence of SEQ ID NO: 119; b. HCDR1 of the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 135, HCDR2 comprises the amino acid sequence of SEQ ID NO: 203, and HCDR3 comprises the amino acid sequence of SEQ ID NO: 137, and LCDR1 of the light chain variable region comprises the amino acid sequence of SEQ ID NO: 138, LCDR2 comprises the amino acid sequence of SEQ ID NO: 139, and LCDR3 comprises the amino acid sequence of SEQ ID NO:

140. 3 . The anti-ILT4 antibody according to claim 1 or 2 , which is a murine antibody, a chimeric antibody, a humanized antibody or a fully human antibody; preferably a humanized antibody.

4. The anti-ILT4 antibody according to any one of claims 1 to 3, wherein a. the heavy chain variable region comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 184 or 185, and the light chain variable region comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 187 or 186; or the heavy chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 32, and the light chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 33; or b. the heavy chain variable region comprises an amino acid sequence that is at least 70% identical to SEQ ID NO: 211, 205, 206, 207, 208, 209, or 210, and the light chain variable region comprises an amino acid sequence that is at least 70% identical to SEQ ID NO: 212, 213, or 214; or the heavy chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 40, and the light chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 41; or c. the heavy chain variable region comprises an amino acid sequence that is at least 70% identical to SEQ ID NO: 181, 176, 177, 178, 179, or 180, and the light chain variable region comprises an amino acid sequence that is at least 70% identical to SEQ ID NO: 183 or 182; or the heavy chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 28, and the light chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 29; or d. the heavy chain variable region comprises an amino acid sequence that is at least 70% identical to SEQ ID NO: 193, 190, 191, or 192, and the light chain variable region comprises an amino acid sequence that is at least 70% identical to SEQ ID NO: 194, 195, or 196; or The heavy chain variable region comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 10, and the light chain variable region comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO:

11. amino acid sequence; or e. the heavy chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 163, and the light chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 225 or 164; f. the heavy chain variable region comprises an amino acid sequence that is at least 70% identical to SEQ ID NO: 197 or 198, and the light chain variable region comprises an amino acid sequence that is at least 70% identical to SEQ ID NO: 199 or 200; or the heavy chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 36, and the light chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 37; or g. the heavy chain variable region comprises an amino acid sequence that is at least 70% identical to SEQ ID NO: 217, 218, 219, 220, or 221, and the light chain variable region comprises an amino acid sequence that is at least 70% identical to SEQ ID NO: 222 or 223; or the heavy chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 42, and the light chain variable region comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 43; Preferably, a. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 184 or 185, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 187 or 186; or The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 32, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 33; or b. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 211, 205, 206, 207, 208, 209 or 210, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 212, 213 or 214; or The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 41; or c. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 181, 176, 177, 178, 179 or 180, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 183 or 182; or The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 28, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 29; or d. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 193, 190, 191 or 192, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 194, 195 or 196; or The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 10, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 11; or e. The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 163, and the light chain variable region An amino acid sequence comprising SEQ ID NO: 225 or 164; f. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 197 or 198, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 199 or 200; or The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 36, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 37; or g. the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 217, 218, 219, 220 or 221, and the light chain variable region comprises the amino acid sequence of SEQ ID NO: 222 or 223; or The heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 42, and the light chain variable region comprises the amino acid sequence of SEQ ID NO:

43.

5. The anti-ILT4 antibody according to any one of claims 1 to 4, wherein the anti-ILT4 antibody is an antibody fragment; preferably, wherein the antibody fragment is Fab, Fab', F(ab')2, Fd, Fv, scFv, dsFv or dAb.

6. The anti-ILT4 antibody according to any one of claims 1 to 4, wherein the anti-ILT4 antibody comprises a heavy chain constant region and a light chain constant region; Preferably, the heavy chain constant region is a human IgG1 or IgG4 heavy chain constant region, and the light chain constant region is a human κ light chain constant region; More preferably, the heavy chain constant region comprises the amino acid sequence of SEQ ID NO: 240 or 171, and the light chain constant region comprises the amino acid sequence of SEQ ID NO:

172.

7. The anti-ILT4 antibody according to claim 6, wherein the anti-ILT4 antibody comprises a heavy chain and a light chain, wherein: a. the heavy chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 228, and the light chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 229; or b. the heavy chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 234, and the light chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 235; or c. the heavy chain comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 226, and the light chain comprises an amino acid sequence that has at least 70% sequence identity to SEQ ID NO: 227; or d. the heavy chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 230, and the light chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 231; or e. the heavy chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 238, and the light chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 239; or f. the heavy chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 232, and the light chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 233; or g. the heavy chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 236, and the light chain comprises an amino acid sequence having at least 70% sequence identity to SEQ ID NO: 237; Preferably, a. the amino acid sequence of the heavy chain is shown in SEQ ID NO: 228, and the amino acid sequence of the light chain is shown in SEQ ID NO: 229; or b. the amino acid sequence of the heavy chain is shown in SEQ ID NO: 234, and the amino acid sequence of the light chain is shown in SEQ ID NO: 235; or c. the amino acid sequence of the heavy chain is shown in SEQ ID NO: 226, and the amino acid sequence of the light chain is shown in SEQ ID NO: 227; or d. the amino acid sequence of the heavy chain is shown in SEQ ID NO: 230, and the amino acid sequence of the light chain is shown in SEQ ID NO: 231; or e. the amino acid sequence of the heavy chain is shown in SEQ ID NO: 238, and the amino acid sequence of the light chain is shown in SEQ ID NO: 239; or f. the amino acid sequence of the heavy chain is shown in SEQ ID NO: 232, and the amino acid sequence of the light chain is shown in SEQ ID NO: 233; or g. The amino acid sequence of the heavy chain is shown in SEQ ID NO: 236, and the amino acid sequence of the light chain is shown in SEQ ID NO:

237.

8. A pharmaceutical composition comprising the anti-ILT4 antibody of any one of claims 1 to 7 and one or more pharmaceutically acceptable carriers, diluents or excipients; preferably, the pharmaceutical composition further comprises at least one second therapeutic agent; more preferably, the second therapeutic agent is an anti-PD-1 antibody.

9. An isolated nucleic acid encoding the anti-ILT4 antibody of any one of claims 1 to 7.

10. A host cell comprising the isolated nucleic acid of claim 9. 11 . A method of blocking the binding of ILT4 to HLA-G in a human subject in need thereof, the method comprising administering to the human subject an effective amount of the anti-ILT4 antibody according to any one of claims 1 to 7.

12. A method for detecting an ILT4 peptide or a fragment thereof in a sample, the method comprising contacting the sample with the anti-ILT4 antibody according to any one of claims 1 to 7, and detecting the presence of a complex between the anti-ILT4 antibody and the ILT4 peptide or a fragment thereof; wherein detection of the complex indicates the presence of the ILT4 peptide or a fragment thereof.

13. A method for treating a disease, comprising administering to a subject a therapeutically effective amount of the anti-ILT4 antibody according to any one of claims 1 to 7 or the pharmaceutical composition according to claim 8; Preferably, the disease is a tumor; more preferably, the disease is selected from astrocytoma, glioblastoma, bladder cancer, bone cancer, brain cancer, breast cancer, carcinoid, cervical cancer, choroid plexus papilloma, colorectal cancer, fallopian tube cancer, ependymoma, gallbladder cancer, gastric cancer, head and neck cancer, idiopathic myelofibrosis, kidney cancer, renal pelvis tumor, leukemia, liver cancer, esophageal cancer, lung cancer, lymphoma, medulloblastoma, melanoma, meningioma, Merkel cell carcinoma, mesothelioma, polyps, leukemia, hepatocellular carcinoma ... Myeloma, neuroblastoma, oligodendroglioma, ovarian cancer, peritoneal tumors, pancreatic cancer, polycythemia vera, primary neuroectodermal tumors, prostate cancer, retinoblastoma, salivary gland cancer, sarcoma, small intestine cancer, colorectal cancer, squamous cell carcinoma, thyroid cancer, endometrial cancer, vestibular schwannoma, blastoma, teratoma, pituitary cancer, vulvar cancer, thymoma, testicular cancer, bile duct cancer, pheochromocytoma, paraganglioma, and adenoid cystic carcinoma; Most preferably, the disease is selected from ovarian cancer, lung cancer, esophageal cancer, colorectal cancer, renal cell carcinoma and melanoma.

14. The method for treating a disease according to claim 13, further comprising using a second therapeutic agent; preferably, the second therapeutic agent comprises an immune checkpoint inhibitor; more preferably, the second therapeutic agent is an anti-PD-1 antibody.

15. The method for treating a disease according to claim 14, wherein the anti-PD-1 antibody comprises a heavy chain variable region PD-1-VH and a light chain variable region PD-1-VL, wherein: The PD-1-VH comprises: a PD-1-HCDR1 comprising the amino acid sequence of SEQ ID NO: 250, a PD-1-HCDR2 comprising the amino acid sequence of SEQ ID NO: 251, and a PD-1-HCDR3 comprising the amino acid sequence of SEQ ID NO: 252; and the PD-1-VL comprises: a PD-1-LCDR1 comprising the amino acid sequence of SEQ ID NO: 253, a PD-1-LCDR2 comprising the amino acid sequence of SEQ ID NO: 254, and a PD-1-LCDR3 comprising the amino acid sequence of SEQ ID NO: 255; Preferably, The PD-1-VH comprises the amino acid sequence of SEQ ID NO: 256, and the PD-1-VL comprises the amino acid sequence of SEQ ID NO: 257.

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