Appended IgGs are a class of bispecific antibodies that are engineered by appending IgGs with additional antigen-binding units, such as scFvs, Fabs, single domain Abs or protein scaffolds. There has been a such appended IgG in clinical trial. The ﬂexibility to choose valency makes appended IgGs an alternative for BsAb development. For now, the widely described formats of appended IgGs include IgG-scFv, IgG-Fv, scFv4-Ig, etc.
Fv-IgG: Fv-IgG is a bispecific, tetravalent molecule that the VH and VL domains of an IgG are appended with similar domains from another antibody. It has 2+2 antigen-binding valency. (Cat. BSDG)
IgG-Fv: IgG-Fv, bispecific and 2+1 antigen-binding valency, is formed by appending the HC of an IgG with Fv from a second antibody at the C-terminus. The utilization of KIH technology facilitates to form heterodimers. (Cat. BSGV)
IgG(L)-scFv: Two scFvs are fused to the C-terminus of light chain of a second antibody. IgG(L)-scFv is specific and bivalent for each antigen. (Cat. IGLFV)
ScFv4-Ig: scFv4-Ig is generated by adding a scFv to CH1 domain and another scFv to the CL domain. It is bispecific and has 2+2 antigen-binding valency. (Cat. FVTIG)
scFv-IgG: A scFv can be fused to the N-terminus of the HC or LC of an IgG to form scFv-(H)IgG or scFv-(L)IgG. It is bispecific and bivalent for each antigen. (Cat. BSSG)