Human leukocyte antigen (HLA) class I presents intracellular peptides to the immune system on the cell surface. Since this process is crucial for the recognition of cancer cells and the initiation of anti-tumor immunity, peptides presented by HLA are valuable immunotherapy targets. More stable peptide HLA (pHLA) complexes provoke superior immune responses. However, how peptide sequence motifs contribute to pHLA stability is not well understood.
We developed a high-throughput assay to quantify stability of thousands of user-defined pHLA produced in E. coli. Peptide libraries and the desired HLA are produced and form pHLA complexes in E. coli. pHLA are purified and stability is evaluated by treating pHLA with a thermal gradient and recovering only the peptides which remain HLA-bound after heat treatment. Peptide depletion over the temperature range is monitored by quantitative tandem mass tag (TMT) enabled mass spectrometry.
Our new E. coli-based method is reliable for assessing pHLA stability. Detected HLA-binding peptides have the expected binding motifs, and stability data strongly correlates with current gold-standard data. We are able to generate large peptide stability datasets (1,800+ peptides) in one scaled experiment — five times larger than currently available datasets. We show that peptide motifs and anchor residue combinations potentially drive pHLA stability. Additionally, peptides were included in user-defined libraries with public immunogenicity annotations. We observed that immunogenic peptides were significantly more stable than non-immunogenic peptides.
We generated customizable pHLA stability datasets which show how peptide sequence motifs affect pHLA stability, and may be helpful for improving our mechanistic understanding of pHLA stability. Further, since peptide stability is related to immunogenicity, these large-scale pHLA stability datasets will be useful for improving peptide immunogenicity predictions for the development of immunotherapeutics.
NIH R01CA155010, Mark Foundation for Cancer Research, Moderna
Classical and Non-Classical Antigen Presenting Cells (APC)
M. Wilbrink, Luis O Correa-Medero, Emma C Duggan et al.· Journal of Immunology· 0 citations
T cell-mediated immune surveillance is critical for cancer control, yet its role in bone marrow malignancies remains poorly understood. Here, we integrate TCR profiling, HLA immunopeptidomics, and functional screening to characterize tumor-reactive T cells in the bone marrow of patients with multiple myeloma (MM) and acute myeloid leukemia (AML). These cells are transcriptionally defined by a conserved effector program distinct from the exhausted phenotype of tumor-reactive T cells in solid cancers. Immunopeptidomic profiling reveals a partially shared antigen landscape enriched for noncanonical peptides driving convergent TCR responses. We develop TFiT (tumor-reactive features in T cells), a transcriptional classifier that identifies these cells and stratifies immunotherapy, but not chemotherapy, response across independent MM and AML cohorts, supporting its specificity for T cell-mediated tumor control. These findings reveal a latent but activatable anti-tumor T cell compartment in bone marrow malignancies and provide a framework for engaging endogenous immunity in MM and AML.
N. Kehl, T. Wagner, Simon Steiger et al.· Cancer Cell· 0 citations
De novo design of protein binders targeting extended, multi-site interaction surfaces remains difficult for current generative methods, which often produce limited structural diversity and predominantly helical topologies. Here, we advance diffusion-based binder design by guiding protein backbone generation through “seeds,” which are PDB-derived fragments selected for geometric complementarity to the target surface. To test this approach, we computationally generated seed-guided binders of the bacterial toxin RelE. RelB, the native antitoxin of RelE, engages two distinct interfaces with high surface complementarity, making it an appropriate test case. Seed-guided RFdiffusion produced backbones with substantially higher structural diversity and more target contacts than RFdiffusion alone. Experimental screening of 1,402 designs in a high-throughput bacterial survival assay identified multiple functional binders, including variants with nanomolar to low-micromolar affinity and one design with RelE neutralization comparable to RelBpep. Computational structure prediction and mutational analyses support that the designed interfaces rely on seed-derived contacts and adopt binding modes distinct from RelB. Molecular dynamics simulations and hydrogen-deuterium exchange experiments further suggest that one high-affinity design undergoes a conformational change upon binding. Notably, successful designs exhibited reduced cross-reactivity to RelE orthologs compared with RelBpep, suggesting that the extensive interfaces generated through seed-guided design can enable enhanced selectivity. These results establish motif scaffolding of surface-complementing seeds as an effective strategy for overcoming current limitations of de novo generative models, enabling the design of proteins that can engage challenging interface sites.
D. Britton, Dia A. Ghose, J. Halpin et al.· bioRxiv· 0 citations