NeoScreen Technology Overview
The NeoScreen platform combines more than a decade of experience in MHC/epitope binding assays with a high level of automation, allowing rapid and accurate immunogenicity screening of libraries containing thousands of neo-epitopes, as well as epitopes from viruses, bacteria, biologics and vaccines.
The stability of the MHC/peptide complex is a critical and often overlooked parameter when determining epitope immunogenicity.1 It is well documented that the stability of the MHC/epitope complex is a better indicator of immunogenicity than affinity.2 To this end, NeoScreen offers the unique combination of highly sensitive affinity and stability assays to assess MHC I and II/epitope complexes, thus reducing the inaccuracies and false positives that are often obtained through affinity-only approaches. By leveraging Immunitrack’s outstanding capabilities in MHC II manufacture, NeoScreen opens up the unique possibility for immunogenicity screening using MHC II. Inclusion of MHC II is imperative in cancer vaccine efforts given that up to 80% of relevant neo-epitopes from cancer may be presented by MHC II.3
NeoScreen Affinity Assays
Computational prediction methods exist for identification of MHC-binding peptides, for example NetMHC. Although widely used, such methods tend to be imprecise and over-predictive, i.e. they often identify a substantial proportion of false positives.4
Immunitrack’s NeoScreen platform provides state-of-the-art peptide/MHC affinity measurements through very sensitive MHC/epitope affinity assays. These affinity assays involve measuring the amount of peptide-MHC formation at various peptide concentrations and under non-stressful experimental conditions. The data obtained enables the calculation of a dissociation constant (Kd value). This assay format is commonly used and data from similar assays has been used to train immunogenicity prediction algorithms such as that underlying netMHC, which is currently seen as the gold standard for immunogenicity predictions.
NeoScreen affinity assays can measure the direct binding of peptides of bacterial, viral, or neo-epitopes origin to MHC I or MHC II molecules. Our growing repository currently contains more than 70 different MHC I and 20 MHC II alleles, including murine alleles. These assays have been validated in several NIH-funded projects and peer-reviewed articles, and account for more than 200,000 Kd measurements in the Immune Epitope Database (IEDB).
NeoScreen Stability Assays
As alluded to above, the stability of the MHC/peptide complex may be the most important parameter when determining epitope immunogenicity, and this must be assessed to reduce false positive epitope binders.
NeoScreen stability assays work by measuring the decay of MHC/peptide complexes under stress-inducing conditions, such as pH or temperature changes or urea denaturation. From this, a half life can be determined for each MHC/peptide complex. Reference peptides are included in all assays and the data yielded from test epitopes is expressed as a % of the reference peptide. All NeoScreen stability assays are amenable to high throughput screening and do not require any peptide modifications.
Accurately Separate and Rank Epitopes with NeoScreen
The combination of affinity and stability measurements generated with NeoScreen assays allows for better separation and ranking of immunogenic epitopes than alternative prediction approaches (Figure 1). Depending on the desired immune response our clients and partners can then pick the ‘best’ epitope(s) to take forward for therapeutic development.
Figure 1. Affinity and stability analysis of 30 CMV-derived peptides. Stability is calculated relative to an included reference peptide (HA306-318). Traditionally, epitopes with a Kd below 100 nM were considered potentially immunogenic. Applying that to the CMV epitopes analysed here would render half of the dataset potentially immunogenic. However, only three of these peptides display a stable interaction with MHC. Of these, two (denoted by red circles) were confirmed as T cell epitopes through ELISPOT and tetramer analysis, thus confirming that stability is a better predictor of immunogenicity than affinity.
NeoScreen Workflow
Immunitrack’s NeoScreen platform can help your company to identify MHC-restricted CD4 or CD8 epitopes from any pathogen, virus, or cancer, fast and with unmatched precision. Figure 2 outlines the workflow and typical results.
Figure 2 Typical NeoScreen workflow
A. Client provides us with the sequence of their biotherapeutic or the sequence of their viral, bacterial or neo-antigen. B. We will help you assess, design and produce the peptides you wish to analyse. These peptides are subsequently screened with MHC molecules of interest (see list of available MHC alleles here). C. Using our NeoScreen platform, we will assess which epitopes bind the chosen MHC molecules, and identify those most likely to elicit a T cell response. D. We then produce a report which contains the raw data from the analysis conducted. E Data may be applied for drug development e.g. vaccine optimisation or drug safety assessment. F. We can produce the MHC/epitope pairs that form stable interactions so that our client can carry out further investigations at their own facilities. G. Flow cytometry studies may be performed using our MHC monomer and tetramers.
For NeoScreen Binding Assay Ordering and Quotations
Please contact us by email at info@immunitrack.com or use our online contact form ▸
In order to provide you a quote, we ask you to provide the following information:
- The number of affinity and stability measurements you require for each MHC allele.
- A list of the MHC alleles you wish to test.
- Are you providing the peptides to be analysed, and if yes in which format?
Confidentiality
We find that we can offer the best service when we hold an informal teleconference with prospective customers before starting any quotation process. During this meeting, we would go through your project goals and needs to find the workflow that can best fulfill your requirements. To initiate a meeting with us, please complete a confidentiality disclosure agreement (CDA). You can find the link to our CDA template just below.
Download CDA Form ▸
