Immunogenicity of therapeutic proteins Flashcards
What is serum sickness?
f.e. when given antibodies from a horse to a human
IgE-mediated immune response against foreign antibodies -> IgE builds complexes with foreign Ab -> deposited in joints, skin eruptions,…
-when given a second time, the immune system is primed for the foreign antibody and it can lead to an anaphylactic shock
How is ADA immune response different from a normal immune response?
-ADA immune response doesn’t have an immunological memory
-antibodies go away when treatment ends and rechallenge doesn’t result in an immediate response
Why are ADAs built, even when the injected protein has the same sequence as the human protein (f.e. human insulin)
-Protein aggregates have repetitive patterns (such as in viruses and bacterial surfaces) -> which triggers B-cell recognition by Toll-like receptors
What are the factors influencing Immunogenicity?
-Sequence variation
-Glycolysation (non-glycosylated proteins are more prone to aggregation->triggering immune response)
-Contaminants and Impurities
-Formulation, route of administration, dose
-length of therapy, patient, assay technologies
Structural factors influencing Immunogenicity
-Number and location of amino acid variability:
-> 1 AA change might have less effect than 10
-> Changes on the MHC binding site might have a bigger impact
-Absence of glycosylation (proteins from E.coli generate more ADAs) -> AGGREGATION -> Immune response
-> f.e. PEGylated antibodies are more soluble and are less likely to produce ADA
Impurities that drive Immune responses
-Virus, yeat, bacteria cell components triggering immune response: G-C rich DNA (60% G-C in bacteria -> triggering immune response) or LPS in the product
-Chromatographic resin is a polymer that can trigger an immune response
-Protein aggregates by shaking, pH, temperature, handling, oxidation
What factors in the formulation and storage influence Immune response?
-Ultra-lyophilized and stored at lower temperature triggers less immune response -> compared to Lyophilized, and stored at room temperature products
-Storage temperature and Purity making a difference
How does the immune status influence immune responses?
-Immunocompromised patients may generate less ADA (it takes longer to generate the immune response 6 months - a year)
-Patients with chronic infections (hepatitis) may generate stronger ADA response
How can immunogenicity be predicted?
Apart from showing efficacy data, companies must show ADA generating capacity of the biological drug (how quickly does the drug generate ADAs)
-they test the drug with CD4+ T-cells to see if an immune response is created/ how long it took -> IN VITRO
-animal testing -> IN VIVO
How can immunogenicity be reduced?
-change amino acid sequences that are prone to cause aggregation
-co-administer immunosuppressant drugs like methotrexate and azathioprine to suppress ADAs
-co-administer peptides (Tregitopes) that are recognized by Treg Cells (Tregs suppress immune responses)
