Immunitrack’s Platform for Epitope Binding Assays to MHC I and II: NeoScreen™

NeoscreenTM from Immunitrack is a leading platform technology for study of Major Histocompatibility Complex class I and class II (MHCI&II) interaction with epitopes of interest.

NeoScreen™ allows Immunitrack to rapidly screen libraries with thousands of (neo)epitopes. Depending on the desired immune response, our clients can then pick the best candidates for taking forward, for example in therapeutic development projects. Epitopes from viruses, bacteria, but also from biologics, vaccines and cancer, may be presented by MHC class I (for somatic cells) and MHCII (for antigen presenting cells)

What you get from NeoScreen™

  • By combining both affinity and stability assessment of MHC-epitope binding, the NeoScreen™ platform reduces inaccuracies and false positives that can be seen when using affinity-only approaches.
  • By leveraging Immunitrack’s unique capabilities in MHC II manufacture, NeoScreen™ opens up the possibility for immunogenicity screening using MHC II. Up to 80% of relevant neo-epitopes from cancer may be presented by MHC II.

Potential Areas of application:

  • Vaccines: Development of new potent vaccines.
  • Immuno-oncology: Neo-epitope selection for personalized cancer vaccine, screening for new cancer specific epitopes.
  • Biologics: develop biologics that are tolerized by cohorts of patients.
  • Biomarker: customized MHC-epitope complexes to monitor specific T cell populations in patients or mice.

NeoScreen™ for MHC I Affinity and Stability

Computational, predictive methods to identify MHC binding peptides exist. However, they tend to be imprecise and over-predictive, i.e. identify a substantial proportion of false positives.

Immunitrack offers state of the art peptide MHC affinity measurements by very sensitive assays. The assays use nanomolar concentrations of MHC I and measure the direct binding of peptide to MHC . The assays have been validated in several NIH funded projects and peer reviewed articles, accounting for more than 100.000 Kd measurements in the Immune Epitope Database (IEDB).

Peptide-MHC stability is a better indicator of immunogenicity than affinity (Eur J Immunol. 2012 Jun;42(6):1405-16). Our stability assay measures the decay of MHC I complexes at physiological temperature enabling precise half-life determinations. All assays are amendable for HTS screening and do not require any modifications of peptide.

Affinity measurements of 4 tumor antigen peptides, MART-1 WT (Kd~23nM) binds nearly 10 times weaker than the A27L mutant (Kd~2 nM). Stability assessment of the two MART-1 variants shows an increased stability of the A27L variant compared to WT (Half-lives: 8 and 2 Hrs respectively).

NeoScreen™ for MHC II Affinity and Stability

For MHC I it has been shown that stability is a better indicator of immunogenicity than affinity. In-house data from Immunitrack supports this hypothesis for MHC II. Our stability assay measures the decay of MHC II complexes at physiological temperature enabling precise half-life determinations. All assays are amendable for high-throughput screening (HTS) and do not require any modifications of peptide.

NeoScreen™ Affinity vs. Stability data for Epstein-Barr Virus (EBV) with MHC II Alleles

Figure shows two EBV derived peptides of nearly equal affinity (Kd of 1 and 6 nM). Though both peptides show strong affinity to DRB1*15:01 only the known T cell epitope (orange) have a high stability or long half-life, underlining the importance of stability analysis.

NeoScreen™ Affinity vs. Stability data for Cytomegalovirus (CMV) with MHC II Alleles

NeoScreen™ Stability vs. Affinity data. Peptides with a Kd lower than ~100 nM are normally considered potential T Cell epitopes. This figure underlines the fact that affinity not necessarily correlates with stability and that stability assessment is a better measure for peptide immunogenicity. x axis: Kd measurements of CMV derived peptides, y axis: stability measurements on same peptides, 100% reference peptide is not shown. Red circles represents “true” CD4 T cell epitopes identified by Elispot and MHC II tetramer analysis (PLoS One. 2014; 9(4)).