Antibody Discovery

Antibody discovery with synthetic peptide antigens that mimic complex targets

antibody-discoveryA major stumbling block in therapeutic antibody discovery is often the inability to generate potent antibodies, especially when the target antigen is complex in nature (GPCR’s, ion-channels) and cannot be obtained as a structurally intact protein. Pepscan’s unique and proven protein mimicry technologies provide an elegant and effective way to arrive at superior antigens for monoclonal antibody generation, in particular against these complex targets. Pepscan’s approach for the generation of antibodies is based on gaining structural knowledge of the target protein and the subsequent synthesis of CLIPS peptide-based immunogens.

Our successful development of antibody therapeutics relies on the ability to:

  • define precisely the antigens at the level of single amino acids
  • adequately mimic the native secondary and tertiary structure of the antigen
  • translate these CLIPS peptides into active and potent immunogens that induce the desired antibodies

Our cutting-edge technologies are specifically designed to reconstruct such structurally complex binding sites and the platform has shown to be compatible with the well established antibody generation methods such as hybridoma and phage display.
Pepscan’s approach enables access to targets that is not easily accessible using conventional methods, and therefore unlocks the full potential of this target class for antibody therapeutics. In addition it allows tailoring antibody response to certain GPCR domains and hence to engineer antibodies which fulfill certain biological requirements. Pepscan’s approach has meanwhile resulted in several proprietary monoclonal antibodies in preclinical development, and in successful antibody discovery partnerships with leading pharmaceutical companies. For more information, please contact us here.


Case example: Development of anti-CXCR2 antibodies

hCXCR2-reconstruction

Peptide reconstruction of extracellular regions of hCXCR2. N-terminus: (DSFEDFWKGEDLSNYSYSSTLPPFLL-DAAPCEPELEINK) (black structure) and ECL3 (DTLMRTQVIQETCERRNHIDR) (dark grey) were connected by a disulfide bond or a CLIPS moiety. The biotin moiety (grey square) for antibody phage display panning is located at the C-terminal side of the N-terminus.

The CXC chemokine receptor-2 (CXCR2) is a member of the large ‘family A’ of G-protein-coupled receptors and is overexpressed in various types of cancer cells. CXCR2 is activated by binding of a number of ligands, including interleukin 8 (IL-8) and growth-related protein a (Gro-a). Monoclonal antibodies capable of blocking the ligand-receptor interaction are therefore of therapeutic interest; however, the development of biological active antibodies against highly structured GPCR proteins is challenging.
In a collaboration with Astra Zeneca/Medimunne, Pepscan identified IL-8 binding sites on CXCR2 by screening of peptide libraries using the HiSense platform. Subsequently structured peptides mimicking the ligand binding site were designed and synthesized.

These peptide mimics were then used in phage display panning to enrich for a population of binders, and subsequently this population was challenged with receptor overexpressing cells. The scFvs from the resulting CXCR2 specific phage clones were sequenced and converted into monoclonal antibodies. The obtained antibodies bound specifically to CXCR2 expressing cells and inhibited the IL-8 and Gro-a induced ß-arrestin recruitment with IC50 values of 0.3 and 0.2 nM, respectively.
Hence the combination of these techniques provided a successful strategic approach for the development of functional monoclonal antibodies against CXCR2 in a relatively small campaign, and might be applicable for other, notoriously difficult, GPCR targets.

Reference: R.S. Boshuizen et al: A combination of in vitro techniques for efficient discovery of functional monoclonal antibodies against human CXC chemokine receptor-2 (CXCR2). mAbs 6:6, 1415–1424; 2014