Inhibitory leukocyte immunoglobulin-like receptors (LILRBs)

Strategic choices for new drug research and development Under the increasingly mature new drug research and development path, antibody discovery is easy to do, and targets are difficult to find.
If you want to be First-in-class, new targets and new mechanisms will be the key points of strategic choice, and inhibition Leukocyte immunoglobulin-like receptors LILRBs will be one of the choices for new mechanisms and new targets.

Inhibitory leukocyte immunoglobulin-like receptors (LILRBs) The leukocyte Ig-like receptor subfamily B LILRB is a class of once-transmembrane glycoproteins.
The extracellular region of this type of protein has Immunoglobulin-like (Ig-like) domain, the intracellular region has an ITIM motif (Immunoreceptor tyrosine-based inhibitory motif).

The family members include LILRB1, LILRB2, LILRB3, LILRB4, and LILRB5, also known as CD85J, CD85D, CD85A, CD85K and CD85C; there is also a closely related member LAIR1.

LILRBs will be potential targets for the development of new drugs, especially tumor drugs.
The reason is that, firstly, they contain ITIM motifs.
Membrane receptors can activate the ITIM motifs in the receptor cells by binding to the corresponding ligands, and go through a series of signals.
After transmission, it inhibits the activation of T cells.
LILRBs and immune checkpoint proteins such as CTLA4, PD-1 and other identical ITIM motifs are a new type of immune checkpoint protein molecule.

Secondly, several members of LILRBs will also be directly expressed on the surface of tumor cells and directly play a role in maintaining the growth and development of tumor cells.

In view of the versatility of LILRBs for tumor cells, targeting LILRBs will play a variety of regulatory functions for tumor therapy.

The R&D pipeline of LILRBs is a new type of target, and there are not many R&D pipelines disclosed on a global scale.
The representative company is IMMUNE ONC.

Some of the pipelines that are progressing rapidly are as follows: BND-22 is a "first-in-class" humanized IgG4 monoclonal antibody targeting the LILRB1 receptor.
The target is to treat solid tumors and is developed by Biond Biologics.

By blocking the immune suppression caused by the interaction of HLA-G and LILRB1, it can activate the innate and adaptive immunity mediated by T cells, macrophages, and NK cells, and clinical trials are expected to start in mid-2021.

As a promising new immune checkpoint drug, BND-22 is also favored by Sanofi.

It is reported that the two parties signed a global exclusive license agreement on January 12, 2021.
Biond Biologics will receive a cash advance of US$125 million from Sanofi, and is entitled to a milestone payment of more than US$1 billion, as well as future product sales sharing.

Image source: Biondbio's official website IO-202 is a monoclonal antibody targeting the immunosuppressive receptor LILRB4 of IMMUNE ONC.
As an antibody inhibitor targeting myeloid checkpoint (myeloid checkpoint), it is truly first in class.

It is currently in clinical phase I, and its indications are Acute Myeloid Leukemia (AML) and Chronic Myelomonocytic Leukemia (CMML).
Among them, the treatment of AML obtained the orphan drug designation granted by the FDA in October 2020.
The following figure reveals its In addition to the principle of action in the treatment of AML, Immune-Onc is also expanding its indications for solid tumors and other hematomas. Image source: Immune-Onc's official website Jounce Therapeutics' JTX-8064 is a specific antibody that targets LILRB2.
LILRB2 is mainly expressed in myeloid cells such as monocytes, macrophages, and dendritic cells.
It interacts with MHC-I, The binding of ANGPTLs and other tumor microenvironment-related ligands can lead to immunosuppression, while JTX-8064 can block the immunosuppressive effect of ligands such as HLA-G (see the figure below).

The Phase 1 clinical trial of JTX-8064 has been officially launched in early 2021 and the enrollment of patients has been completed.
The clinical trial protocol includes JTX-8064 single agent and combination with PD-1 inhibitor.

Image source: Jounce SITC-2020 posterNC410 is the second drug in the R&D pipeline of NextCure, a company founded by star scientist Professor Xie Ping.
NC410 is a LAIR-2 fusion protein that can be used as a bait to capture LAIR-1 by blocking LAIR -1 combines with collagen to release immunosuppressive effects, thereby enhancing the functions of T cells and dendritic cells and exerting anti-tumor activity.

In addition, IO-106 in the pipeline of Immune-Onc is also aimed at the target of LAIR-1 and is currently in the preclinical development stage.

The difference is that IO-106 is a monoclonal antibody, and the mechanism is also to block the binding of LAIR-1 to collagen.

LILRB function and antibody discovery case sharing Although the clinical trials of LILRBs are the last two years, research on LILRBs antibodies as potential drugs has already been carried out in the scientific research community.
As early as 2012, Junke Zheng et al.
reported the function of LILRB2.

Angiopoietin-like proteins (ANGPTLs) protein family is an important ligand of LILRB2, of which ANGPTL5 has the strongest effect, and its affinity with LILRB2 is 5nM.

ANGPTs family proteins are expressed in abundance in many cells.
These soluble proteins can be secreted by hypoxia and directly or indirectly affect the activity of hematopoietic stem cells and leukemia stem cells in the body. Xun Gui (2019, etc.
) has verified the mechanism of LILRB4-mediated T cell suppression through a lot of work, and developed a humanized neutralizing antibody for LILRB4--mAb h128-3, which can block APOE's activation of LILRB4 Effect, and then release the inhibitory effect on T cells, and finally achieve the goal of killing tumors.

In addition, h128-3 can also mediate ADCC and ADCP to further enhance immune efficacy (see the figure below for details).

Image source: Reference 1 The author has further studied the recognition epitope of the antibody and found that mAb h128-3 binds to the D1 domain of LILRB4, and if E54A, R56Q and P103S in the D1 domain are mutated, mAb h128-3 The ability to bind to the D1 domain will be greatly reduced.

This work has certain guiding significance for subsequent antibody discovery work.

Image source: Reference 1 Mitsunori Shiroishi et al.
studied the binding of LILRB1 and LILRB2 to MHC class I molecules, and found that the two are more inclined to bind to HLA-G, and they mainly bind through D1D2.

This has certain guiding significance for immunization and antibody screening strategies.

Image source: Reference 5 Based on the in-depth understanding of the target and the study of the structure, Kai Tu Biology has developed a series of LILRB family proteins, domains, and different polymer forms of the ligand HLA-G protein to help the research of differentiated antibodies.

ELISA data SPR data Human LILRB2 D1&D2 captured on Protein A Chip can bind HLA-G, His Tag with an affinity constant of 6.
5 μM as determined in SPR assay (Biacore T200).
Human LILRB2 captured on Protein A Chip can bind HLA-G, His Tag with an affinity constant of 9.
20 nM as determined in SPR assay (Biacore T200).
For details, please contact: Website: Email: support@kactusbio.
com Hotline: 400-614-0008 Tel: Shanghai area: 15021367472 , 18256917205 Jiangsu, Shandong: 17827834427 Zhejiang Beijing: 15801006807 Other regions: 18256917205 Kactus Biosystems is an innovative protein and antibody international biotechnology company driven by research and development, mainly focusing on the immunotherapy and diagnostic market.

Kai Tu Bio focuses on global innovative drug research and development corporate customers, providing CRO services and catalog products based on structural design of functional target proteins, especially membrane proteins.

The main founding team of Kai Tu Biology comes from scientists and business managers with many years of experience in the biomedical industry from world-class companies and research institutions.

Reference 1.
Gui X, Deng M, Song H, et al.
Disrupting LILRB4/APOE Interaction by an Efficacious Humanized Antibody Reverses T-cell Suppression and Blocks AML Development[J].
Cancer Immunology Research, 2019, 7(8): canimm.
0036.
2019.
2.
Zheng J, Umikawa M, Wang HY, et al.
Inhibitory receptors bind ANGPTLs and support blood stem cells and leukaemia development[C]// 2012 National Conference on Developmental Biology Abstract Collection.
2012.
3.
Kang X, Kim J, Deng M.
Inhibitory leukocyte immunoglobulin-like receptors: Immune checkpoint proteins and tumor sustaining factors[J].
Cell Cycle, 2016, 15(1):25-40.
4.
Deng M, Lu Z, Zheng J, et al.
A motif in LILRB2 critical for Angptl2 binding and activation[J].
Blood, 2014, 124(6):924-935.
5.
Mitsunori Shiroishi, Kouhei Tsumoto, Katsumi Maenaka, et al.
Human inhibitory receptors Ig-like transcript 2 (ILT2) and ILT4 compete with CD8 for MHC class I binding and bind preferentially to HLA-G.
PNAS July 22, 2003 100 (15) 8856-8861.
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