Transforming Tumor Research: Engineering MHCs as Versatile Reagents

ManHee Suh's Talk @ CAR-TCR Summit

We are delighted to share with you our experience at the 8th CAR-TCR Summit in Boston as part of the KACTUS team. Our Chief Technology Officer, ManHee Suh, presented his work on "Transforming Tumor Research: Engineering Major Histocompatibility Complexes (MHCs) as Versatile Reagents," which received a positive response from the audience. This presentation focused on engineering major histocompatibility complexes to improve the reliability and flexibility of tools used to study antigens, T cell recognition, and immune-driven treatment development in cancer.

We are excited to share the remarkable results from our in-house data with you. If you're interested in our research, we encourage you to fill out the form and receive more information on test samples, along with a full copy of the poster. We understand the importance of this work, and we're here to support you every step of the way. Our goal is to provide practical, assay-ready solutions that make it easier to study peptide–MHC interactions with better consistency and specificity.

Why MHC Engineering Transforms Tumor Research

Preview of In-House Data

When dealing with solid tumors lacking specific biomarkers, the effectiveness of adoptive T cell therapy using CAR-T treatments is limited. The absence of dependable, multifaceted MHC reagents has been a hindrance in the research and development of treatments for solid tumors. To tackle this challenge, we have engineered MHC molecules in several formats with diverse applications. These improved MHC molecules have the potential to facilitate solid tumor research and development.

In this context, “versatile reagents” are engineered MHC tools that support multiple workflows, from antigen screening to immune monitoring, without introducing avoidable variability in antigen presentation or peptide display. This matters because many tumor cells and cancer cells express targetable antigens unevenly, and assays need consistent surface expression of peptide–MHC complexes to interpret immune recognition.

MHC fundamentals: class I vs class II presentation

The major histocompatibility complex comprises MHC class I and II systems that display antigenic peptides (also called MHC peptides) to T cells. In class I presentation, peptide–MHC complexes primarily engage CD8 T cells and drive cytotoxic t cells and cytotoxic T lymphocyte activities that can eliminate target cells. In contrast, mhc class II and MHC class II molecules (also referred to as class II MHC molecules and class II molecules) support MHC class II presentation to helper T cells, which shape broader immune coordination and downstream immune response quality. Both pathways influence T cell activation and overall immune system function in tumor biology and immunotherapy.

Why “Versatility” Depends on Stable Peptide Loading

Many cancer studies depend on presenting a defined peptide from specific antigens in a consistent format. If peptide occupancy varies, assay readouts can shift even when the biology is unchanged. Engineering strategies can improve the stability and reproducibility of peptide display, which supports accurate identification of antigen-specific receptors, clearer comparisons across targets, and stronger confidence in downstream decisions for treatment development.

SCT (Single-Chain Trimer) MHC for High Peptide Occupancy

Figure 1. Structural analyses of over 200 TCR-peptide MHC I/II complexes reveal that the linkers in SCT MHC are not in close proximity to the TCR-peptide-MHC interfaces.

How SCT design supports high occupancy and consistent readouts

Single-chain trimer (SCT) designs are one approach to engineering mhc reagents to maintain high peptide occupancy. In SCT formats, key molecules are combined in a single chain so the intended peptide is less likely to exchange, supporting more consistent detection of target-specific T cells and more reliable functional assays. This approach can improve assay-to-assay comparability because changes in readouts are more likely to reflect biology rather than instability in peptide loading.

Engineering class II MHCs: intracellular routing and endosomal processing

For mhc class II reagents, correct intracellular trafficking can affect the final peptide repertoire and assay fidelity. In vivo, class II loading occurs within endosomal and lysosomal compartments (including lysosomal compartments) as part of an intracellular pathway that prepares peptides for display on the cell surface. Engineering strategies may incorporate trafficking elements such as a sorting signal to direct constructs toward lysosomes, which can support enhanced presentation and more consistent MHC class II presentation in model systems. This biology links to markers like lysosomal associated membrane protein, which is often used to describe lysosome-related localization in cell biology workflows.

Why This Matters for Tumors, Vaccines, and Immune Profiling

Engineered MHC reagents can support tumor programs in three practical ways:

1. Antigen and receptor screening: By presenting defined antigenic peptides, teams can identify receptors with better specificity, including receptors that distinguish tumor-derived targets from self antigens.

2. Immune monitoring: Stable peptide–MHC presentation supports clearer detection of responding t cells, helping interpret immune dynamics in cancer.

3. Vaccine evaluation: In vivo immunization experiments, consistent antigen display helps researchers compare vaccine potency, measure antibody titers, and evaluate whether immune priming drives measurable t cell activation and cell activation.

These applications also intersect with autoimmune research, because class II presentation of self antigens can contribute to autoimmune diseases when tolerance mechanisms fail.

Evidence Context and Translational Relevance

In published immunology literature, results suggest that engineered routing and stable peptide display can improve the interpretability of peptide–MHC assays across different experimental systems. In some studies, mice demonstrated measurable immune shifts when antigen presentation variables were controlled, supporting more reproducible comparisons across targets and formats. This type of reagent design is also relevant for pathogen and tumor contexts, including human papillomavirus antigen studies, where consistent peptide–MHC display can influence detection sensitivity and downstream interpretation.

Research Ecosystem and Collaboration

KACTUS supports this broader research ecosystem by providing mammalian-expressed MHC molecules and MHC peptides in assay-ready formats that help teams standardize antigen presentation and improve comparability across studies. In collaborative programmes spanning academia, biotech, and translational groups, researchers often need consistent reagents for MHC class I workflows (to profile cytotoxic T cells and CD8-driven recognition) as well as MHC class II workflows (to evaluate MHC class II molecules, class II MHC molecules, and MHC class II presentation relevant to helper T cells). 

To complement these reagents, KACTUS also offers soluble TCR expression services and SPR analysis services to characterize peptide–MHC–TCR interactions, supporting specificity checks and binding performance during candidate selection. For projects that require tailored constructs or formats, KACTUS can also support customized designs to match target HLA alleles, peptide sequences, or experimental readouts, helping researchers translate engineered MHC reagent design into actionable data for immune profiling and therapeutic development.

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If you're interested in learning more about our research and accessing the full copy of ManHee Suh's poster, simply submit the form below. By doing so, you'll also receive information on how to obtain test samples for further exploration.