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Applications of VHH Antibodies

Biointron 2025-01-20 Read time: 6 mins
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VHH antibody targets in the tumor microenvironment. DOI: 10.1186/s12951-024-02900-y

VHH antibodies, derived from camelid single-domain antibodies, have a small size, high stability, and high binding affinity, making them ideal candidates for a wide range of therapeutic and diagnostic applications. From advancing cancer immunotherapies to combating infectious diseases and autoimmune disorders, VHH antibodies are reshaping traditional approaches and driving innovation across the life sciences.

Applications in Cancer Therapeutics

VHH antibodies have wide-ranging applications in cancer therapy. These antibodies have been engineered into various therapeutic formats, such as VHH-based chimeric antigen receptors (VHH-CARs), bispecific killer cell engagers (BiKEs), and antibody-drug conjugates (ADCs).

Examples include CD38-specific VHH-CARs for multiple myeloma (MM) cell elimination and VHH-based BiKEs promoting natural killer (NK) cell-mediated MM cell killing. Additionally, VHH antibodies targeting immune checkpoint proteins, such as PD-1, enhance T-cell responses in resistant tumors. HER2- and EGFR-specific VHH antibodies improve tumor penetration and therapeutic outcomes, while VHHs targeting MUC1 sensitize breast cancer cells to drug therapy.

Humanization strategies have also emerged to reduce the risk of immune reactions. Techniques such as grafting antigen-specific VHH sequences onto human scaffolds or replacing camelid-derived complementarity-determining regions (CDRs) with human CDRs ensure the preservation of binding affinity while increasing compatibility. For instance, humanized anti-EGFR VHH antibodies fused with tumor-penetrating peptides have demonstrated improved antitumor activity.

VHH antibodies have also proven effective in CAR-T cell applications, exhibiting comparable efficacy to scFvs while offering enhanced stability and solubility. For example, CD19-targeted CAR-T cells using VHHs showed promising results in preclinical studies, indicating their potential as an alternative to traditional CAR therapies.

Related: Conventional Antibodies, Heavy Chain-Only Antibodies, and VHH Antibodies

PD-L1 as a Target: Immune Checkpoint Inhibition

Immune checkpoint inhibitors using VHH antibodies have gained traction as targeted therapies for solid tumors. Envafolimab, a humanized single-domain PD-L1 antibody fused with an IgG1 Fc fragment, exemplifies this approach. Its small size and solubility enable subcutaneous administration and enhanced tumor penetration. Clinical trials have demonstrated its efficacy in treating various solid tumors and MSI-H/dMMR cancers, offering a viable alternative to intravenous checkpoint inhibitors.

However, the limitations of current PD-1/PD-L1 therapies, such as poor T-cell infiltration in the tumor microenvironment, have driven the development of bispecific T-cell engagers (BiTEs). VHH-based BiTEs targeting PD-L1 and CD3 redirect cytotoxic T cells to tumor sites, increasing intratumoral immune cell levels and improving therapeutic outcomes.

One promising approach involves bispecific VHH antibodies designed for PD-L1-overexpressing melanoma. Structural modeling and molecular docking identified optimal binding sites, enabling efficient T-cell activation. Preclinical studies using PD-L1-targeted BiTEs demonstrated significant tumor suppression, highlighting their potential in advanced melanoma therapies.

Related: Anti-Mouse Antibodies

EGFR as a Target

The epidermal growth factor receptor (EGFR) plays a critical role in malignant tumor development, but its targeting poses challenges due to risks of on-target, off-tumor toxicity. VHH antibodies have been adapted to address these limitations through innovative formats, such as multivalent and bispecific designs.

A tetravalent biparatopic VHH-drug conjugate (S7 ADC) demonstrated potent antitumor activity by effectively downregulating EGFR expression. By binding multiple EGFR epitopes, these conjugates synergistically reduce receptor activation and drive therapeutic efficacy. Another strategy involves combining VHH antibodies targeting EGFR with NK-cell-mediated lysis, achieving enhanced cytotoxicity in colorectal cancer models.

Additionally, VHH-based immunotoxins targeting EGFR have shown promise in treating solid tumors. For example, an EGFR-targeting VHH fused with the fungal ribotoxin α-sarcin achieved superior tumor cell killing in preclinical models. These advancements position VHH antibodies as versatile tools for overcoming resistance in solid tumor therapies

Applications in Infectious Disease Therapies

VHH antibodies have emerged as potent agents against infectious diseases, particularly viral pathogens such as SARS-CoV-2. Mechanisms include blocking receptor-binding domain (RBD) interactions, preventing viral entry, and neutralizing viral strains. For example, VHH antibodies such as Nb-H6 and Nb4 effectively target SARS-CoV-2 RBDs, demonstrating efficacy against Omicron variants. Their small size and high specificity make them suitable for intranasal or systemic administration.

Beyond SARS-CoV-2, engineered VHH antibodies targeting respiratory syncytial virus (RSV) have shown superior therapeutic efficacy compared to conventional treatments. ALX-0171, an RSV-specific VHH antibody, demonstrated a threefold increase in potency compared to existing monoclonal antibody therapies.

In bacterial infections, VHH antibodies have proven effective in neutralizing toxins. For instance, anti-Clostridium difficile VHH antibodies have been developed for targeted toxin neutralization, showcasing their utility in combating gastrointestinal pathogens.

Emerging Applications in Autoimmune and Neurological Diseases

In autoimmune diseases, VHH antibodies have been integrated into approved therapies, such as Caplacizumab, which targets von Willebrand factor (vWF) to treat thrombotic thrombocytopenic purpura (TTP). Other examples include trivalent VHH antibodies like ozoralizumab, targeting TNF-α in rheumatoid arthritis, and sonelokimab, designed for dual inhibition of IL-17A and IL-17F in psoriasis.

In neurological disorders, VHH antibodies offer potential for penetrating the blood-brain barrier (BBB). For example, anti-transferrin receptor VHH antibodies fused with neurotensin enable targeted delivery of therapeutics to the CNS. Similarly, brain-penetrating VHHs targeting amyloid-beta aggregates in Alzheimer’s disease models have reduced pathological markers and improved cognitive outcomes in preclinical studies.

At Biointron, we are dedicated to accelerating antibody discovery, optimization, and production. Our team of experts can provide customized solutions that meet your specific research needs, including VHH Antibody Discovery. Contact us to learn more about our services and how we can help accelerate your research and drug development projects.

 

References:

  1. Alexander, E., & Leong, K. W. (2024). Discovery of nanobodies: A comprehensive review of their applications and potential over the past five years. Journal of Nanobiotechnology, 22, 661. https://doi.org/10.1186/s12951-024-02900-y

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