An anti-idiotype/anti-idiotypic antibody (Anti-ID Ab) binds to the idiotype of another antibody, usually an antibody drug. An idiotype can be defined as the specific combination of idiotopes present within an antibody's complement determining regions. Since anti-idiotype/anti-idiotypic Abs are capable of binding to antibody drugs within biological fluids, they are commonly used in preclinical setting for antibody drug pharmacokinetics (PK) and pharmacodynamics (PD). Due to the similarity between anti-idiotype/anti-idiotypic Abs and anti-drug antibodies, anti-idiotype/anti-idiotypic Abs are also commonly used as reference standard for antibody drug immunogenicity, anti-drug antibody (ADA) studies.
There are 3 types of anti-idiotype/anti-idiotypic Abs: Antigen-blocking & Non-blocking and Complex-specific antibody. Due to the fact that Complex-specific antibody is usually difficult to develop, the first two types (Antigen-blocking & Non-blocking) are usually applied, and the content of bound drug can be obtained by calculation.
Specifically binding to the idiotype of antibody drug, Anti-ID Ab is an indispensable tool in pharmacokinetic study for detecting and quantitating Ab drug in human and animal serum. Due to the good homogeneity and specificity of anti-ID monoclonal antibody, It is recommended for usage in the preclinical stage, pharmaceutical research and clinical stage.
And for Anti-ID polyclonal antibody or antigen capture ELISA could be used in drug discovery stage. In terms of detection sensitivity, mouse Anti-ID mAb can be developed for ng-level detection. If the sensitivity is expected to reach the pg level, the development of rabbit anti-ID mAb is also the option. Due to the similarity between anti-ID and anti-drug antibody, it can also be used as a positive control of anti-drug antibody in immunogenicity study for the determination of total anti-drug antibody. Specifically, anti-ID polyclonal antibodies is recommended as the positive control of anti-drug antibody due to its high coverage property, which could simulate anti-drug antibody to the greatest extent. For the detection of neutralizing anti-drug antibody, anti-ID mAb which could block the binding of drug to target shall be developed as control. Pharmacokinetic and immunogenicity analysis cover the whole process of biologics development. As an essential tool antibody, anti-ID is not only one of the critical reagents for IND filing, but also widely used in the clinical stage.
