Peptides bound to class I major histocompatibility complexes (MHC) play a critical role in immune cell recognition and can trigger an antitumor immune response in cancer. Surface MHC levels can be modulated by anticancer agents, altering immunity. However, understanding the peptide repertoire's response to treatment remains challenging and is limited by quantitative mass spectrometry-based strategies lacking normalization controls. We describe an experimental platform that leverages recombinant heavy isotope-coded peptide MHCs (hipMHCs) and multiplex isotope tagging to quantify peptide repertoire alterations using low sample input. HipMHCs improve quantitative accuracy of peptide repertoire changes by normalizing for variation across analyses and enable absolute quantification using internal calibrants to determine copies per cell of MHC antigens, which can inform immunotherapy design. Applying this platform in melanoma cell lines to profile the immunopeptidome response to CDK4/6 inhibition and interferon-γknown modulators of antigen presentation uncovers treatment-specific alterations, connecting the intracellular response to extracellular immune presentation.

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Metastases are a major cause of cancer mortality. AXL, a receptor tyrosine kinase (RTK) aberrantly expressed in many tumors, is a potent oncogenic driver of metastatic cell motility and has been identified as broadly relevant in cancer drug resistance. Despite its frequent association with changes in cancer phenotypes, the precise mechanism leading to AXL activation is incompletely understood. In addition to its ligand growth arrest specific-6 (Gas6), activation of AXL requires the lipid moiety phosphatidylserine (PS). PS is only available to mediate AXL activation when it is externalized on cell membranes, an event that occurs during certain physiologic processes such as apoptosis. Here it is reported that exposure of cancer cells to PS-containing vesicles, including synthetic liposomes and apoptotic bodies, contributes to enhanced migration of tumor cells via a PS-Gas6-AXL signaling axis. These findings suggest that anti-cancer treatments that induce fractional cell killing enhance the motility of surviving cells in AXL-expressing tumors, which may explain the widespread role of AXL in limiting therapeutic efficacy.

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Combining multiple therapeutic strategies in NRAS/BRAF mutant melanoma—namely MEK/BRAF kinase inhibitors, immune checkpoint inhibitors (ICIs), and targeted immunotherapies—may offer an improved survival benefit by overcoming limitations associated with any individual therapy. Still, optimal combination, order, and timing of administration remains under investigation. Here, we measure how MEK inhibition (MEKi) alters anti-tumor immunity by utilizing quantitative immunopeptidomics to profile changes in the peptide major histocompatibility molecules (pMHC) repertoire. These data reveal a collection of tumor antigens whose presentation levels are selectively augmented following therapy, including several epitopes present at over 1,000 copies per cell. We leveraged the tunable abundance of MEKi-modulated antigens by targeting four epitopes with pMHC-specific T cell engagers and antibody drug conjugates, enhancing cell killing in tumor cells following MEK inhibition. These results highlight drug treatment as a means to enhance immunotherapy efficacy by targeting specific upregulated pMHCs and provide a methodological framework for identifying, quantifying, and therapeutically targeting additional epitopes of interest.

Peptides bound to class I major histocompatibility complexes (MHC) play a critical role in immune cell recognition and can trigger an antitumor immune response in cancer. Surface MHC levels can be modulated by anticancer agents, altering immunity. However, understanding the peptide repertoire's response to treatment remains challenging and is limited by quantitative mass spectrometry-based strategies lacking robust normalization controls. We describe a novel approach that leverages recombinant heavy isotope-coded peptide MHCs (hipMHCs) and multiplex isotope tagging to quantify peptide repertoire alterations using low sample input.HipMHCs improve quantitative accuracy of peptide repertoire changes by normalizing for variation across analyses and enable absolute quantification using internal calibrants to determine copies per cell of MHC antigens, which can inform immunotherapy design. Applying this platform in melanoma to profile the immunopeptidome response to CDK4/6 inhibition and interferon gamma, known modulators of antigen presentation, we uncovered treatment-specific alterations, connecting the intracellular response to extracellular immune presentation.

Regulation of the immune response contributes to the severity and outcomes in various disease conditions. Bioactive immunomodulatory biomaterials have shown promise for influencing these responses to promote tissue repair and regeneration. In this study, we investigated the role of mast cells in the regulation of the immune response to biomaterial scaffolds. In mast cell-deficient mice, there was dysregulation of the expected M1 to M2 macrophage transition typically induced by the biomaterial scaffold. Polarization progression deviated in a gender specific manner with an early transition to an M2 profile in female mice, while the male response was unable to properly transition past a pro-inflammatory M1 state. Both were reversed with mast cell adoptive transfer. Further investigation of the later stage immune response in male mice determined a sustained pro-inflammatory gene expression profile in deficient mice consisting of members from the IL-1 cytokine family and related downstream pathways. As mast cells were mainly associated with detrimental pro-inflammatory outcomes for biomaterial scaffolds, these results demonstrate their contribution to induced immunomodulatory therapies and support their potential as a critical immune regulatory element that can be manipulated for stimulating endogenous tissue repair.

Each year, nearly 19 million people die of cardiovascular disease with coronary heart disease and myocardial infarction (MI) as the leading cause for the progression of heart failure. Due to the high risk associated with surgical procedures, a variety of minimally invasive therapeutics aimed at tissue repair and regeneration are being developed. While biomaterials delivered via intramyocardial injection have shown promise, there are challenges associated with delivery in acute MI. In contrast, intravascularly injectable biomaterials are a desirable category of therapeutics due to their ability to be delivered immediately post‐MI via less invasive methods. In addition to passive diffusion into the infarct, these biomaterials can be designed to target the molecular and cellular characteristics seen in MI pathophysiology, such as cells and proteins present in the ischemic myocardium, to reduce off‐target localization. These injectable materials can also be stimuli responsive through enzymes or chemical imbalances. This review outlines the natural and synthetic biomaterial designs that allow for retention and accumulation within the infarct via intravascular delivery, including intracoronary infusion and intravenous injection.This article is protected by copyright. All rights reserved