Scientific basis for assessing immunogenicity risk from peptide-related impurities, including T-cell recognition and anti-drug antibody formation.
For peptide-related impurities, a sequence change can alter immune recognition even when the impurity remains structurally similar to the active peptide. This is why immunogenicity becomes a central safety endpoint.
Adaptive immunity
Peptide fragments can be presented by HLA/MHC molecules and recognized by T cells.
T-cell help and antibodies
CD4+ T-cell activation can support B-cell responses and anti-drug antibody formation.
Clinical consequences
Anti-drug antibodies can affect efficacy, pharmacokinetics or safety depending on the product and immune response.
Comparative assessment
The key question is whether the impurity introduces a new or stronger immunological determinant relative to the reference peptide.
Frequently asked questions
Does every sequence difference increase immunogenicity?
No.
Why focus on MHC-II/HLA-II?
It has a direct mechanistic relationship with CD4+ T-cell help and anti-drug antibody formation.
Can immunogenicity be predicted perfectly?
No. In silico and in vitro methods provide evidence with uncertainty.
Should the impurity be compared with the API?
Yes, comparative interpretation is central.
