Scientists at Creative Biolabs are pleased to introduce our bispecific single domain antibody service, which combines our unparalleled expertise in both the single domain antibody and bispecific antibody field. Much like validated recombinant antibody formats such as tandem scFv, single domain antibodies against the same as well as different targets can be designed and engineered into bivalent and bispecific formats with excellent bioactivity and stability.

Background

Bispecific antibodies (bsAbs), which are capable of simultaneous binding to two different targets, are considered the most promising solution to increase therapeutic activity by retargeting a large variety of payloads to cancer cells. However, the potential application of those antibody formats has been significantly limited due to the difficulty in producing large amounts of homogenous preparations of bispecific antibodies. None of them have met so far all the requirements to become a standard format for clinical applications. Being the smallest fully functional antibody fragments, single domain antibodies have many outstanding physical properties, such as high production yields and good stability, and may accelerate the way toward this goal.

Fig. 1 Various formats of bispecific antibodies relying on the use of single domain antibodies. (Patrick Chames, 2011)

Bispecific Single Domain Antibody Production Services

With over 10 years of experience in antibody engineering, Creative Biolabs has been a recognized leader in the fields of single domain antibody production and single domain antibody library. We have tried various approaches to create bispecific antibodies using single domain antibodies, among which a commonly used strategy is to link two single domain antibodies via a peptidic linker, thereby creating a tandem single domain antibody. We have successfully produced a few bispecific single domain antibodies with neutralization activity obtained using a specially designed linker based on the hinge region of the llama IgG2a isotype. As these single domain antibodies are small, very efficiently produced, and highly stable, they represent ideal building blocks to create more elaborate molecules, especially bispecific antibodies.

Published Data

• Bispecific VHH-Based CD1d-specific Vγ9Vδ2-T Cell Engager Development

Fig. 2 The bispecific anti-CD1d-Vδ2 VHH activates Vγ9Vδ2-T cells. (Iris de Weerdt, 2022)

Vγ9Vδ2-T cells form a conservative subset of T cells, which can induce apoptosis of many kinds of malignant cells in a manner independent of human leukocyte antigen. In addition, natural killer (NK) cell receptors allow Vγ9Vδ2-T cells to recognize malignant cells through stress ligands. After activation, the functions of Vγ9Vδ2-T cells include cytotoxicity, secretion of chemokines and proinflammatory cytokines, and antigen presentation. These characteristics have led to clinical trials aimed at developing the anti-tumor potential of Vγ9Vδ2-T cells. Vγ9Vδ2-T cells can recognize and cleave chronic lymphocytic leukemia (CLL) cells. Bispecific single domain antibodies have recently been shown to overcome synaptic formation disorders in CLL patients. In order to selectively activate Vγ9Vδ2-T cells and direct them to CLL cells, researchers generated a Vγ9Vδ2-T cell engager based on the variable domain of camel-derived heavy chain antibody (VHH). The scientists analyzed the expression of CD1d in 78 untreated CLL patients and showed that CD1d was a suitable target for CLL bispecific Vγ9Vδ2-T cell engager. The data show that the bispecific Vγ9Vδ2-T cell engager based on VHH can activate Vγ9Vδ2-T cells in healthy controls and CLL patients, resulting in specific cleavage of CD1d. In conclusion, this CD1d-specific bispecific single-domain antibody shows the potential of immunotherapy with Vγ9Vδ2-T cells in CLL.

FAQ

1. What are bispecific single domain antibodies? How do they work?

   A bispecific single-domain antibody is an engineered antibody designed to bind two different antigens or two different epitopes at the same time. This bi-specificity enables antibodies to regulate two different biological pathways in one therapy at the same time to enhance the therapeutic effect. Bispecific sdAb is usually small, so it can better infiltrate into tissues, such as the tumor microenvironment. In cancer treatment, these antibodies can be designed to recognize specific markers on the surface of tumor cells at one end and immune cells at the other, thus directing immune cells directly to tumor cells and promoting the death of tumor cells.

2. What is the difference between bispecific single-domain antibodies and traditional bispecific antibodies?

   Traditional bispecific antibodies are usually based on complete antibody molecules, including two heavy chains and two light chains, while bispecific single-domain antibodies are composed of smaller sdAbs. This structural difference makes sdAbs smaller in size and easier to produce and modify. In addition, small single-domain antibodies can more easily penetrate dense tumor tissue, providing faster tissue distribution and higher penetration, which is particularly important in the treatment of difficult-to-treat cancers such as solid tumors.

3. What are the challenges faced by bispecific single domain antibodies in clinical applications?

   The efficacy and safety of bispecific single-domain antibodies need to be verified by rigorous clinical trials. For example, because these antibodies can interact with multiple targets at the same time, they may lead to unexpected immune reactions or toxic problems. In addition, the production process of bispecific sdAbs is more complex than that of traditional antibodies and requires precise design and manufacturing processes to ensure stability and functionality. Finally, because of their high penetrating power, they may harm normal tissue and cause side effects.

4. In which disease areas do bispecific single-domain antibodies show the greatest potential?

   Bispecific single-domain antibodies show great potential in cancer treatment. They can simultaneously target specific antigens on the surface of tumor cells and antigens that activate the immune system, thus promoting the recognition and killing of tumors by the immune system. In addition, these antibodies also show potential in the treatment of autoimmune and inflammatory diseases, which can reduce inflammation and self-attack by regulating the immune system in different ways. Neurodegenerative diseases are also another field. Bispecific single-domain antibodies can target and regulate multiple factors in the pathological process and provide new therapeutic strategies.

Resources

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