Fab-IgG BsAb Generation Service

Creative Biolabs provides custom Fab-IgG BsAb design and construction services for scientific and clinical researches. Fab-IgG BsAb is a format of appended IgGs which has longer half-life than conventional IgGs. With innovative scientists and many years of service experience in bispecific antibody (BsAb), Creative Biolabs offers the reliable and efficient services to meet our customer’s individual requirements.

BsAbs endow antibodies with the ability of targeting two different targets. Generally, there are five classes of immunotherapeutics: bispecific IgGs, appended IgGs, bispecific fragments, bispecific fusion proteins and bispecific conjugates. According to their structural characteristics, these molecules can be produced by hybrid hybridoma, genetic engineering or chemical conjugation. For appended IgGs, they are not the natural IgG formats and generated by recombinant technology. In order to overcome the BsAb chains-mispairing, various strategies including knobs-into-holes (KIH), charge pair, CrossMab, etc. are developed. FBM BsAbs have two tandem Fabs linked to Fc domain without chain-mispairing problems. As shown in the figure, FBM BsAbs, also known as Fab-IgGs, are composed by four Fab fragments and Fc domain and they are developed by rearranging antibody DNA sequences into three constructs and co-expressing.

Fab-IgG BsAbs retain the biological properties of their parental antibodies and have several typical features and advantages making them a promising BsAb format in different areas of researches.

• Fab-IgG BsAbs are tetravalent and symmetric bispecific antibodies with four independent antigen binding sites (Fab fragments) to bind two targets;
• Standard Fc domains are used in Fab-IgG BsAbs and there is no Fc mutation required which can fully maintain the function of Fc and antibody naturally characteristics;
• There are no scFv elements needed, which avoid the non-function of scFv caused by misfolding.
• Peptide connector or linker is optional. The resulting Fab-IgG BsAbs have appropriate flexibility allowing dual binding;
• Less artificial sequence and construct make Fab-IgG BsAbs easier expressed and there are no unexpected by-products in the production process;
• The heavy and light chains can be paired correctly and the expressed molecules are in correct orientation.

It has been demonstrated that Fab-IgG BsAbs have similar properties to conventional antibodies at some level:

• Due to the features of Fab-IgG BsAbs, they can be expressed in good quantities and purified in one-stop;
• Fab-IgG BsAbs have similar affinity binding to separate epitope and comparable stability and solubility;
• The pharmacokinetic profile of Fab-IgG BsAbs is comparable to their parental antibodies.

As a novel format of BsAb, Fab-IgG BsAbs will attract more attention from scientists and clinicians of different areas including oncology, immunology, hematology, etc. And according to your specific requirements, scientists from Creative Biolabs will design the most appropriate BsAb construct and assist you to accelerate research process.