Immunogenicity, defined as the ability of a substance to produce an immune response, is key to a successful and safe biopharmaceutical drug development program. Therapeutic Antibodies, enzyme therapies, peptides and combination products can elicit an immune response that may impact their safety and efficacy.
Example of an ELISA assay plate
How Biologics Create an Immune Response
Many types of substances administered to the human body may pose a chance of eliciting an immune response. However, biotherapeutics can be especially immunogenic because the large size of these molecules can trick the body into thinking that they are foreign invaders, triggering action by the immune system. These large molecules can also denature, which changes their profile, or aggregate, creating even larger particles. Ultimately, these characteristics can change or increase a biotherapeutic’s immunogenicity profile.
New technologies have been created – for example, PEGylation –to reduce the immunologic effect of biotherapeutics. However, the efficacy of these attempts to reduce immunogenicity varies. It is for this reason that testing for immunogenicity of a product in development is so important. Furthermore, immunogenicity testing is still necessary in a biosimilar development program. This is because the small changes in the manufacturing of biotherapeutics can effect large changes in their immunogenicity profile. Thus biosimilars, which almost invariably will be manufactured under different conditions than their parent biologics, still need to be tested for immunogenicity.
What is Immunogenicity Testing
Immunogenicity assays provide a way to measure the potential immune responses of biologics and biosimilars. Often a single biologic will require a panel of assays to produce a thorough picture of potential immunogenicity. The FDA stipulates that assays should be designed in such a way that they provide sufficient sensitivity, are free from confounding interference, can detect physiological consequences, and account for potential risks based on the profile of the therapeutic and the target patient population.
By designing assays with these factors in mind, it is possible to gather predictive data about the strength and type of immune response that a drug may produce in humans.
Types of Immunogenicity Analysis
For some biologics, a total antibody assay (to measure the antibodies that are part of the immune response) that includes screening, confirmatory and titer components will be sufficient to develop an immunogenicity profile. In other cases a neutralizing antibody assay or cell based bioassay may be necessary and informative. ELISA (enzyme-linked immunosorbent assay) is also a useful method to detect antibody-antigen complexes.
In addition, aggregation potential of a biotherapeutic can be measured using size-exclusion chromatography and HPLC combined with laser-light scattering. This can help to provide a fuller picture of the overall immunogenic profile of a compound.
The goal of all these tests is, ultimately, to predict the clinical effect of patient immune responses to biotherapeutics. The role immunogenicity plays in drug development is an important one. As such, a well thought out and well executed program is a key to producing safe and efficacious biologic therapies.
To learn more about Pacific BioLabs Immunogenicity Testing Services, visit PBL’s Immunogenicity Testing Services page.
Genetic Engineering and Biotechnology news: Proposed Standards for Immunogenicity Testing – http://www.genengnews.com/gen-articles/proposed-standards-for-immunogenicity-testing/4145/
FDA: Immunogenicity of Protein-Based Therapeutics – http://www.fda.gov/BiologicsBloodVaccines/ScienceResearch/BiologicsResearchAreas/ucm246804.htm
Wikipedia: Immunogenicity – http://en.wikipedia.org/wiki/Immunogenicity