Invented by Jean Loup Romet-Lemonne, Michael W. Fanger, Paul M. Guyre, Edmund J. Gosselin, Dartmouth College, Celldex Therapeutics Inc

The market for targeted immunostimulation using bispecific reagents is rapidly growing as researchers and pharmaceutical companies recognize the potential of this innovative approach to treating various diseases. Bispecific reagents are molecules that can simultaneously bind to two different targets, such as a cancer cell and an immune cell, to enhance the immune response against specific diseases. Immunostimulation is the process of activating the immune system to fight against pathogens or abnormal cells, such as cancer cells. Traditional immunostimulatory approaches, such as vaccines or immune checkpoint inhibitors, have shown significant success in certain diseases. However, these approaches often lack specificity, leading to off-target effects and potential toxicity. Bispecific reagents offer a more targeted approach by precisely directing the immune response towards specific cells or molecules. These reagents can be designed to bind to a specific antigen on the surface of cancer cells, for example, while simultaneously engaging immune cells, such as T cells or natural killer cells, to attack the cancer cells. This targeted approach minimizes damage to healthy cells and reduces the risk of adverse side effects. The market for targeted immunostimulation using bispecific reagents is driven by several factors. Firstly, the increasing prevalence of cancer and other diseases that require immunostimulatory treatments has created a significant demand for more effective and specific therapies. Bispecific reagents offer a promising solution by harnessing the power of the immune system to selectively eliminate diseased cells. Secondly, the advancements in biotechnology and antibody engineering have enabled the development of bispecific reagents with improved properties, such as increased stability and enhanced binding affinity. These advancements have facilitated the translation of bispecific reagents from the research stage to clinical applications, attracting the attention of pharmaceutical companies and investors. Moreover, the success of bispecific antibody therapies, such as blinatumomab for acute lymphoblastic leukemia and emicizumab for hemophilia A, has demonstrated the potential of bispecific reagents in the clinic. These therapies have shown remarkable efficacy and safety profiles, paving the way for the development of new bispecific reagents targeting different diseases. The market for targeted immunostimulation using bispecific reagents is also fueled by collaborations between academic institutions, biotechnology companies, and pharmaceutical giants. These partnerships allow for the exchange of knowledge, expertise, and resources, accelerating the development and commercialization of bispecific reagents. However, challenges remain in the development and commercialization of bispecific reagents. The complexity of designing and manufacturing these molecules requires specialized expertise and infrastructure. Additionally, regulatory considerations and reimbursement policies need to be addressed to ensure the widespread adoption of bispecific reagents in clinical practice. In conclusion, the market for targeted immunostimulation using bispecific reagents is expanding rapidly due to the increasing demand for specific and effective immunotherapies. The advancements in biotechnology, successful clinical outcomes, and collaborative efforts are driving the development and commercialization of bispecific reagents. As more research is conducted and more therapies reach the market, the potential of bispecific reagents to revolutionize immunostimulation becomes increasingly evident.

The Dartmouth College, Celldex Therapeutics Inc invention works as follows

Disclosed is a method of stimulating an immune response in a subject to an antigen that the immune response targets. This method involves administering a binding agent that binds to a surface receptor on an antigen-presenting cellular, sometimes without being substantially blocked by the natural receptor ligand, as well as an antigen, to which the immune reaction is targeted, to the subject in a physiologically acceptible medium. The binding agent and antigen are also disclosed in molecular complexes.

Background for Targeted Immunostimulation using bispecific reagents

Antigen molecules can only be recognized by the immune response after they have been internalized by antigen-presenting cell, which are usually mononuclear cells like macrophages or B lymphocytes. The antigen-presenting cell must first internalize the proteinaceous antigen. This antigen is then broken into small peptidic pieces by enzymes found in vesicles within the cytoplasm. The peptides, after fragmentation, are then linked to MHC molecules on the surface of the antigen-presenting cell and presented to the immune response. The T-cell receptor recognizes the peptides in this manner, which activates the T-lymphocytes to mount an immune response. This antigen also stimulates B lymphocytes to produce specific antibodies.

Complexes of antigen and antibody have been used in order to stimulate an immunity response against the antigen. The antigen-antibody-complexes bound to Fc-receptors for IgG, Fc?R, increase the efficiency of antigen delivery and T-cell activation in human and mouse macrophages (Celis and Chang (1985), Immunol. Today 6:245-259; Manca et al. (1988) Immunol. 140:2893-2898; Schalke et al. (1985) J. Immunol. J. Immunol. 139:1609-1616). The Fc region is responsible for the binding of these complexes. This binding can be inhibited by physiological concentrations IgG.

This invention relates to a binding agent that binds an antigen-presenting surface receptor in some cases without being substantially blocked by the natural receptor ligand and which binds antigen.

In one aspect, the binding agent is a bispecific agent, such as heteroantibody, a bispecific antibody or another bispecific molecule with a binding affinity for the antigen, and a receptor surface of an antigen-presenting cells, such as mononuclear macrophages (e.g. a macrophage).

As used in this document, the term “heteroantibody” refers to a conjugate of at least two or more antibody molecules with different specificities. Refers to a compound that contains at least two antibody molecules with different specificities.

An “antibody binding sites” The antibody molecule’s portion that binds to a specific antigenic site is called an “antibody binding site”. This antibody binding site consists of an immunoglobulin domain with three hypervariable areas flanked on either side by four framework regions that are relatively conserved. “The hypervariable region is believed to be responsible the binding specificity for individual antibodies.

The term “bispecific antibodies” refers to a single, divalent antibody that has two different antigen binding sites (variable regions). “A single divalent antibody has two antigen-binding sites (variable region).

A ?bispecific molecule? “A?bispecific molecule?

The bispecific binding agent targets the antigen towards the cell by binding the receptor cellular, such as the Fc receptor. This bispecific binding agents binds to the receptor of the cell in some embodiments without being substantially blocked by its natural ligand. In one embodiment, the bispecific agent binds specifically to an Fc receptor on an antigen-presenting cells for immunoglobulin G without being blocked. Preferred binding agents have a specificity for Fc-RI, Fc-RII and Fc-RIII. “In a preferred embodiment, the agent binds specifically to the high affinity Fc-receptor for immunoglobulin G on macrophages (Fc?RI).

In another aspect of the present invention, an preferred binding agent would be an antibody or a binding fragment thereof that includes one or multiple complementarity-determining regions.

As used in this document, “complementarity-determining region” includes one hypervariable region of an immunoglobulin molecule and selected amino acids disposed in the framework regions which flank that particular hypervariable region. “As used herein,?complementarity determining region? includes one hypervariable area of an antibody molecule as well as selected amino acids located in the framework region which flanks that hypervariable immunoglobulin region.

In some aspects, the binding agent comprises at least two antibodies binding fragments that are linked by chemical means or genetically via recombinant-DNA techniques. A Fab-Fab conjugate is a binding agent that is preferred. The first Fab binds to the high affinity Fc, as described above, while the second Fab binds to the antigen.

The binding agent is used in the invention to stimulate an immune response in a subject to an antigen. This method involves the administration of a binding agents and an antigen in a pharmacologically-acceptable medium to a subject. The binding agent directs the antigen towards the antigen-presenting cells in the subject.

The antigen that is targeted can come from an external pathogen, such as a virus, bacteria, or parasite, or from endogenous host cells, such as tumor-associated antigens found on tumor cells. Binding agents that are preferred include antibodies for antigens from the hepatitis viruses, such as hepatitis surfaces antigens or HIV antigens. Other binding agents bind epitopes on bee venom or pollen.

In general, the antigen will be administered in a preformed complex that is chemically coupled with the binding agent. The antigen can also be incorporated into the agent using recombinant-DNA techniques, creating a genetic hybrid coding for a fusion of the binding agent with the antigen. In some cases the bispecific antigen is administered separately from the binding agent.

In another embodiment, the antigen can be directly bound to the receptor-binding agents to create bispecific molecules. The antigen, for example, can be covalently linked to an antibody that binds the Fc-receptor without being blocked by IgG.

The binding agent that binds to an Fc receptor can also be included in a lipidemulsion, or in the outer layer of the liposome containing the antigen. The binding agent should be an antibody that recognizes the Fc-RI receptor. A vaccine containing the molecular compound of the invention, in a pharmacologically acceptible medium, is another aspect of the invention.

The compositions of the invention can be used for treating or preventing infectious diseases, such as hepatitis B. They also stimulate the immune system when chronic infections of the organism are present, deplete antigens in a subject’s circulation, and treat tumors.

This invention also relates methods and compositions that are used to induce IgG reactions against allergens in order to achieve tolerance when IgE is mediated type I hypersensitivity and to induce T cell tolerance towards allergens, which would interfere with IgE mediated response development. These methods involve the administration of a complex molecule consisting of an allergen that binds IgE to mast cells and basophils. The complexed heteroantibody binds high affinity Fc receptors without being blocked by IgG. The complex is administered in sufficient quantities to induce an immune response, including the production of allergen specific IgG. This inhibits the binding of the allergy to IgE. The complex can also induce a T cell tolerance by binding to B cells that are naive to the allergen. This interferes with the IgE-mediated reaction type I.

An optimal immune response to a antigen dependent on the thymus requires that a B cell receive help from a helper CD4+ T cell. This is only possible because the B cell contains antigen-specific immuneglobulins on its surface. These immunoglobulins allow it to internalize, process and present antigen very efficiently. The macrophage, dendritic cells and other antigen presenting cell types lack antigen specific receptors and lack the highly efficient mechanism of processing and presenting an antigen. The apparent need for adjuvants in administering vaccines indicates that an antigen-presenting cell is needed, as well as the B cell. It appears that the antigen presented by resting resting B cell to resting resting T cell does not result in T cell activation but rather T cell tolerance. (1992) J. Exp. Med. 175:131). This is because the resting B cells fail to send all the necessary signals to activate the resting T cells. The resting B-cell could prevent the induction of tolerance to T cells by the resting T-cell if it first reacts to the antigen present on the antigen presenting cells such as macrophages or dendritic cells (Parker and al. FASEB J. 5:2777). This means that the resting T-cell must first interact before it can interact with the B-cell in the naive person.

These considerations led to the conclusion, that an optimal immunogen must have two major components. One is antigen that can be recognized by antigen-specific cells (B cells) and another component which allows antigen to be efficiently processed and presented to a cell presenting antigen other than a resting B cell. Germain (1991), Nature 353:605. These criteria are met by attaching antigens with anti-Fc antibody receptor antibodies, since antigen directed at Fc receptors of macrophages enhances antigen display at least 100 times (Immunol). Today (1985), 6:245. In vivo studies support the efficacy. In mice, for example, an increase in antibody levels was observed after immunization with a bispecific antibody that targeted antigens to MHC class 2 or Fc RII (Snider and al. (1990) (J. Exp. Med. 171:1957-1963). The requirement for adjuvant has also been eliminated. It is particularly useful to be able to administer immunogens at lower doses, such as allergens, which are toxic when administered at higher doses. Repeated low dose administration can lead to tolerance against certain allergens. Tolerance can be achieved by producing IgG that competes with the allergen-specific IgE and removes the allergen from mast cells coated with IgE. Allergen anti-Fc receptors conjugates can reduce the amount administered of allergen, further reducing the toxicity and at the same increase production of allergen specific IgG.

Click here to view the patent on Google Patents.