Clinical Application of Nanobodies in Six Major Tumors

Traditional antibodies have a molecular weight of about 150KD and a size of 14.
2 nm × 8.
2 nm × 3.
8 nm, which makes the penetration of solid tumors poor and the curative effect of solid tumors is not ideal
.

Nanobodies (heavy chain variable region VHH) from camelids and sharks have a molecular weight of about one-tenth of that of traditional antibodies, giving people hope for the treatment of solid tumors
.

This article summarizes the eight advantages of Nanobodies and their six applications in clinical tumor diagnosis
.

The eight dominant molecules 1 of Nanobodies are small in quantity
.

The molecular weight of 12-14KD is about one-tenth that of traditional antibodies
.

1.
Low immunogenicity
.

The sequences of Nanobody and human IgG heavy chain are more than 80% identical, and the molecular weight is small, so the immunogenicity is weak, and the production of anti-drug antibodies is less
.

Helps avoid the problem of drug resistance caused by repeated medications
.

2.
High stability
.

3.
High degradation resistance
.

It can withstand changes in temperature, pressure and pH, and is easy to store and transport
.

4.
Prokaryotic expression
.

5.
Low mass production cost
.

6.
Good tissue penetration, suitable for imaging diagnosis and treatment of solid tumors
.

7.
Product characterization is easy
.

The structure is simple, the post-translational modification is low, and the homogeneity is good
.

Six applications of Nanobodies.
Molecular imaging cancer can be visually diagnosed through single photon emission computed tomography (SPECT), positron emission tomography (PET), computed tomography (CT), ultrasound and optical imaging
.

Antibodies and nanobodies are linked to radionuclides, positron emitting radioisotopes and near-infrared fluorophores
.

Radionuclides (99mTc, 177Lu, 123I, etc.
) are used for SPECT imaging, while positron emitting radioisotopes (68Ga, 124I, 89Zr, 18F, etc.
) are used for PET imaging
.

Because the nanobody has a small molecular weight and good tissue penetration, the imaging time is fast (1-3 hours), the clearance in the body is also fast, and the tumor/background ratio is higher.
It is a better imaging antibody than traditional monoclonal antibodies
.

Molecular imaging is widely used in: target distribution, antibody drug distribution in vivo, tumor diagnosis and other fields
.

Tumor diagnosis combines a therapeutic compound with a diagnostic radiotracer and performs a diagnostic scan to visualize the accumulation of the compound in cancer cells
.

Radiolabeled Nanobodies can be used to identify specific tumor-related biomarkers, thereby helping cancer diagnosis and determining appropriate treatment methods
.

Nanobodies diffuse rapidly into tissues and accumulate specifically in target tissues (with minimal accumulation in non-target tissues), which results in the rapid generation of high-contrast images, allowing early diagnosis of patients
.

Radiolabeled Nanobodies can be used for whole body scans to detect the distribution of primary tumors and metastatic lesions (as shown in the figure below)
.

Diagnostic scans are helpful in estimating dose, monitoring treatment response, evaluating treatment efficiency and predicting adverse effects of treatment
.

Most tumors in imaging-guided surgery require surgical treatment.
By 2030, 45 million operations may be required in a year globally
.

The purpose of preventive surgery is to remove cancer-prone tissues, with less damage, lower cost, and minimize malignant lesions.
Diagnostic techniques are important for determining appropriate treatment and management of cancer
.

A promising application of Nanobodies in surgery is imaging-guided surgery
.

A mouse human xenograft breast cancer model that combines anti-HER-2Nb (11A4) with IRDye800CW.
Compared with trastuzumab-IRDye800CW, 11A4-IRDye800CW increases tumor accumulation and tumor-to-background ratio (Figure below, literature) 3)
.

And based on image-guided surgery to remove mouse SKBR3 tumors
.

Targeted radiotherapy Radiotherapy is still one of the most cost-effective treatments for tumors, and about 50% of cancer patients receive radiotherapy
.

The purpose of radiotherapy is to expose malignant cells to the maximum radiation dose while exposing normal cells to the minimum radiation dose
.

Radiation damages DNA, which may block cell proliferation and induce cell death
.

Healthy cells can repair themselves quickly, survive and function normally
.

Radiotherapy is usually combined with chemotherapy, surgery, and immunotherapy
.

Although radiotherapy is beneficial, it also has some side effects, such as oral mucositis, liver toxicity, and nephrotoxicity.
Targeted radionuclide therapy (TRNT) can be used to deliver radiation to malignant cells with minimal impact on healthy cells
.

There are two types of TRNT drugs: 1.
Iodine-131 and strontium-89 that naturally accumulate in malignant tissues, and 2.
TRNT drugs that target tumor-associated antigens expressed on the surface of cells
.

Nanobodies have good tissue penetrability, and mark reflective nuclides to target tumor-associated antigens to achieve targeted reflex therapy
.

There are now some animal model studies, showing good results
.

There is a clinical trial registration (NCT03956615), but it has not yet been applied for
.

HER2 single domain antibody labeled 213Bi targeted radiotherapy (Mol.
Pharm.
2020, 17, 3553-3566.
) delivers chemotherapeutic drugs.
Antibody-conjugated drugs use the specific targeting function of antibodies to carry cytotoxic drugs to the tumor
.

Traditional antibodies contain the Fc segment, which causes additional immunotoxicity and metabolic abnormalities due to the binding of Fc and receptors
.

Nanobodies do not contain Fc segment and have good tissue penetration.
Theoretically, they can reduce the occurrence of additional side effects and increase local tumor drugs, thereby reducing the systemic dosage of antibody Eurolink drugs and increasing the therapeutic index
.

Nanobodies can also be used to encapsulate drugs, and can also improve solubility, stability and clearance
.

Several possible forms of immunotherapy using nanobodies as drug delivery vehicles have a century-old history of tumor immunotherapy, including vaccines, cytokines, antibody drugs, immune checkpoint inhibitors, cell therapy and other technologies
.

Nanobodies have higher penetration for solid tumors due to their small molecular weight.
Nanobodies with the same target may produce better therapeutic effects than traditional antibodies
.

KN035 Corning Jerry’s original PD-L1 single-domain antibody is currently cooperating with Simcere and Siide Di to carry out a number of tumor treatment clinical trials (NCT03667170, NCT04034823, NCT04182789, etc.
)
.

Editor's summary Nanobodies have attracted wide attention because of their small molecular weight and good tissue penetration; they can be expressed in prokaryotic cells and are low cost; they are stable in structure and easy to transport
.

There are already some clinical trials of nanobodies used in imaging diagnosis, surgical treatment, immunotherapy and other fields
.

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Ivana Jovčevska et al, The Therapeutic Potential of Nanobodies, BioDrugs.
2020 Feb;34(1):11-26.
2.
Yan Xing et al, Early Phase I Study of a 99mTc-Labeled Anti-Programmed Death Ligand- 1 (PD-L1) Single-Domain Antibody in SPECT/CT Assessment of PD-L1 Expression in Non–Small Cell Lung Cancer, J Nucl Med 2019; 60:1213–12203.
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