Composite Proteins 

Antitope's proprietary Composite Protein™ technology creates therapeutic proteins comprising multiple segments from one or more other proteins in order to avoid T cell epitopes in the final molecule.

Composite Protein™ technology is designed for the generation of non-immunogenic therapeutic proteins. Typically starting with a non-human protein (e.g. bacterial, plant, other mammalian), the resultant Composite Protein™ retains the properties of the original reference protein, but with all immunogenic regions being replaced by a composite of human sequence segments (or sequences related to the original sequence) that are devoid of T cell epitopes. A key step in the generation of composite proteins involves a process of T cell epitope recognition in which sequences are selected for incorporation into proteins by filtering out potential T cell epitopes ("Epitope Avoidance").

Key steps in the generation of a Composite Protein™ are as follows;

(1) Immunogenic regions in the reference protein (T cell epitopes) are identified using EpiScreen™ T Cell Epitope Mapping.

(2) Sequence segments from other proteins, typically human or from related proteins, are identified from protein databases in order to build a library of segments that can be used to replace immunogenic regions.

(3) Protein models of potential composites and the starting reference protein are prepared. Structural information from the protein models is used to identify and compare residues critical for function and protein stability. The position and properties of these residues are taken into account when selecting composite sequence segments.

(4) A library of Composite Protein™  sequence segments (typically >50 sequences) is analyzed for the presence of potential human T cell epitopes (epitope avoidance) by a combination of in silico analysis of peptide-MHC class II binding and searching Antiope's iTope software .

(5) Following T cell epitope analysis, Composite Protein™ variants are produced from the library of T cell epitope depleted sequence segments, replacing T cell epitopes mapped in Stage 1.

(6) One or more lead Composite Protein™ are selected based upon the relative function of individual variants compared to the reference non-human starting protein. Stable cell lines are established for production of additional quantities of lead Composite Protein for further in vitro and in vivo analysis in order to select a lead suitable for clinical trials.

All lead Composite Proteins™ are tested for immunogenicity using EpiScreen™ assays. The final Composite Protein™ lead retains the biological properties of the reference protein, but with any T cell epitopes removed. This process provides suitable leads, with a low risk of immunogenicity for therapeutic and in vivo diagnostic use.