Project description:Immune checkpoint blockade (ICB) has revolutionized cancer treatment, but most patients do not respond. PD-1 blockade “unleashes” CD8 T cells, including those specific for mutation-associated neoantigens (MANA), but factors in the tumor microenvironment can inhibit responses by dampening MANA-specific T cell function. Recent advances in single cell transcriptomics are revealing global T cell dysfunction programs in tumor-infiltrating lymphocytes (TIL). However, the vast majority of TIL do not recognize tumor antigens and little is known about transcriptional programs of true MANA-specific TIL. Here, we use an integrated approach to identify MANA-specific T cell clones using the MANA functional expansion of specific T cells (MANAFEST) assay in neoadjuvant anti-PD-1-treated lung cancers and use their TCR CDR3 as barcodes to track them and analyze their transcriptional programs and function in the tumor microenvironment using single cell RNA sequencing. We find both MANA-and virus-specific clones in TIL and adjacent normal lung, regardless of response status. MANA-specific, influenza (flu)-specific and EBV-specific TIL each have unique transcriptional programs. Most MANA-specific clones are tissue resident memory (TRM) cells, an incompletely activated cytolytic program, including EOMES deficiency, and higher levels of genes encoding T cell inhibitory molecules and Tox2. Notably, MANA-specific T cells express low levels of IL-7R and are functionally less responsive to IL-7 compared with tissue-resident flu-specific clones. MANA-specific clones from anti-PD-1 non-responding tumors express TCR with markedly lower ligand-dependent signaling capability, are largely confined to HOBIThi TRM subsets and coordinately up-regulate genes encoding specific checkpoints, killer inhibitory receptors, and intracellular inhibitors of T cell activation and cytotoxicity. These findings provide mechanistic and potential therapeutic insights into overcoming resistance to PD-1 blockade.

Project description:Introduction Immune checkpoint blockade (ICB) is a systemic therapeutic option for advanced hepatocellular carcinoma (HCC). However, low patient response rates necessitate the development of robust predictive biomarkers that identify individuals who will benefit from ICB. A 4-gene inflammatory signature, comprising CD8, PD-L1, LAG-3, and STAT1, was recently shown to be associated with a better overall response to ICB in various cancer types. Here, we examined whether tissue protein expression of CD8, PD-L1, LAG-3, and STAT1 predicts response to ICB in HCC. Methods HCC samples from 191 Asian patients, comprising resection specimens from 124 patients (ICB-naïve) and pre-treatment specimens from 67 advanced HCC patients treated with ICB (ICB-treated), were analyzed for CD8, PD-L1, LAG-3, and STAT1 tissue expression using multiplex immunohistochemistry followed by statistical and survival analyses. Results Immunohistochemical and survival analyses of ICB-naïve samples showed that high LAG-3 expression was associated with shorter median progression-free survival (mPFS) and overall survival (mOS). Analysis of ICB-treated samples revealed that high proportions of LAG-3+ and LAG-3+CD8+ cells pre-treatment were most closely associated with longer mPFS and mOS. Using a log-likelihood model, adding the total LAG-3+ cell proportion to the total CD8+ cell proportion significantly increased the predictive values for mPFS and mOS, compared with the total CD8+ cell proportion alone. Moreover, levels of CD8 and STAT1, but not PD-L1, were significantly correlated with better responses to ICB. After analyzing viral-related and non-viral HCC samples separately, only the LAG3+CD8+ cell proportion was significantly associated with responses to ICB regardless of viral status. Conclusion Immunohistochemical scoring of pre-treatment levels of LAG-3 and CD8 in the tumor microenvironment may help predict ICB benefits in HCC patients. Furthermore, immunohistochemistry-based techniques offer the advantage of being readily translatable in the clinical setting.

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Intratumoral mregDC and Tfh-like niches enable local reinvigoration of CD8 T cells following PD-1 blockade

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