Antibodies Against Antibodies? Anti-Idiotype mAb Discovery
Monoclonal antibodies (mAbs) are the most successful class of biologics products to date, with most of
the top selling drugs composed of these Y-shaped proteins. The Food and Drug Administration (FDA) has approved 100+ monoclonal antibody therapy, with many others at various stages of development.
In theory, antibodies can be raised against any target, with most approved antibodies targeting cancer related antigens or inflammatory molecules. But what about targeting an antibody with another antibody?
Better known as anti-idiotypic antibodies (or anti-ID for short), these antibodies bind the idiotypic
determinant or antigen binding site of another antibody. Initially discovered in the beginning of the 20th
century, anti-IDs have become an important tool in drug development, such as assessing a therapeutic
antibody’s pharmacokinetics (PK) and serum half-life (t1/2), studying the potential effects of a host’s
immune response to an antibody therapy (in the form of anti-drug antibodies), and in the treatment of B
cell leukemia/lymphomas.
Over the last couple of years, numerous clients have approached Curia with interest in anti-idiotypic
antibodies. A recent campaign was with a “hot” biotech startup for whom we discovered a set of
diverse anti-idiotypic antibodies for their leading candidate mAb.
To discover anti-idiotypic antibodies towards target, we sought to generate a F(ab’)2 as the immunogen
to avoid generating antibodies against the Fc domain of the mAb. In order to generate the F(ab’)2
immunogen, a pepsin digestion of the starting antibody was performed by the process development and
manufacturing group (PDM) based in California.
We immunized our in-house immunologically diverse PentaMiceTM with the F(ab’)2 target domain. We
screened approximated 10,000 hybridomas and obtained 313 hits. A serum interference analysis at the
tertiary stage winnowed down the list to 178 hits with highly desirable features.
Twelve hybridomas were subsequently elected by Client for single cell cloning to obtain monoclonal
hybridomas secreting monoclonal antibodies. Clones were expanded to generate saturated
supernatants, and mAbs were affinity purified using a batch method by the BioProduction group (BP) in
San Carlos, yielding 0.4-1.5 mg of purified antibodies (from 30 mL cultures). Target binding EC50 and
inhibition of target binding IC50 values were determined by ELISA. A diverse range of mAbs were
identified, encompassing competitive blockers, non-competitive blockers, and partial competitive
blockers.
Sequencing was performed by Curia’s Gene to Protein (GTP) group, identifying 11 unique types of mAbs.
Variable region sequence analysis grouped mAbs based on heavy and light chain V and J gene usage and
CDR3 sequences. Additionally, polyspecificity baculovirus particle (BVP) screening and ELISA-based
isotyping were performed, where most antibodies were mIgG1κ isotype and had low polyspecificity
signals.
The anti-ID antibodies we discovered for our client will help inform PK and provide insight into the
mechanism of action of the target throughout its clinical development. Curia looks forward to enabling future clients to turn their antibody ideas into success stories !
“Thank you for the data, looks great, we got some diverse anti-Id mAbs here! We worked with Curia on a great many projects, including antibody discovery and characterization, various biological assays, and assay setup. Each time the Curia team delivered great quality results that allowed us to make informed decisions and move projects forward. Curia teams are accommodating of our diverse and changing needs, they are flexible and easy to work with. They also always deliver results on time. I will highly recommend Curia as a partner for the discovery and early development work.” – Curia Client Testimonial