Patent expiry and biosimilars (revision 8)

Patent protection and regulatory exclusivity together determine when a competitor may market a copy of an approved product. When both lapse, entry becomes possible by one of two routes: as a generic, demonstrating that the active substance is the same, or as a biosimilar, demonstrating high similarity through a comparability exercise.^[1]

Synthetic peptides sit awkwardly between the categories. They are made by chemical synthesis like small molecules, but are large enough that impurity profiles and higher-order structure may differ between manufacturers in ways a small-molecule generic pathway was not designed to address.^[2]

Which pathway applies differs by jurisdiction and by molecule, and guidance specific to synthetic peptide generics has been issued to address exactly this.^[3]

A generic application demonstrates that the active substance is the same as the reference product and that the finished product is bioequivalent. No clinical efficacy trial is generally required.^[1]

A biosimilar application demonstrates high similarity through analytical comparability, supported by pharmacokinetic and, where necessary, clinical data. The bar is similarity rather than identity, because biological manufacture cannot produce identity.^[1]

For a synthetic peptide, identity of the active substance is in principle demonstrable, which points to the generic pathway. What complicates it is that impurities differ between synthetic routes, and an impurity absent from the reference product raises questions a bioequivalence study does not answer.^[3]

Guidance for synthetic peptide generics focuses on the impurity profile: a proposed generic must show that any impurity not present in the reference product, or present at higher level, does not raise a safety or immunogenicity concern.^[3]

This is the same argument that runs through the analytical articles on this wiki. Peptide impurities are structurally close to the peptide, are route-dependent, and are what an adequately specific method exists to resolve. See Solid-phase peptide synthesis.^[2]