Project description:Immune checkpoint blockade (ICB) has improved outcome for patients with metastatic melanoma but not all benefit from treatment. Several immune- and tumor intrinsic features are associated with clinical response at baseline. However, we need to further understand the molecular changes occurring during development of ICB resistance. Here, we collected biopsies from a cohort of 44 melanoma patients after progression to anti-CTLA4 or anti-PD1 monotherapy. Genetic alterations of antigen presentation and interferon gamma signaling pathways were observed in approximately 25% of ICB resistant cases. Anti-CTLA4 resistant lesions had a sustained immune response, including immune-regulatory features, as suggested by multiplex spatial and TCR clonality analyses. One anti-PD1 resistant lesion harbored a distinct immune cell niche, however, anti-PD1 resistant tumors were generally immune poor with non-expanded TCR clones. Such immune poor microenvironments were associated with melanoma cells having a de-differentiated phenotype lacking expression of MHC-I molecules. In addition, anti-PD1 resistant tumors had reduced fractions of PD1+ CD8+ T cells as compared to ICB naïve metastases. Collectively, these data show the complexity of ICB resistance and highlight differences between anti-CTLA4 and anti-PD1 resistance that may underlie differential clinical outcomes of therapy sequence and combination.
Project description:Immune checkpoint blockade (ICB) has improved outcome for patients with metastatic melanoma but not all benefit from treatment. Several immune- and tumor intrinsic features are associated with clinical response at baseline. However, we need to further understand the molecular changes occurring during development of ICB resistance. Here, we collected biopsies from a cohort of 44 melanoma patients after progression to anti-CTLA4 or anti-PD1 monotherapy. Genetic alterations of antigen presentation and interferon gamma signaling pathways were observed in approximately 25% of ICB resistant cases. Anti-CTLA4 resistant lesions had a sustained immune response, including immune-regulatory features, as suggested by multiplex spatial and TCR clonality analyses. One anti-PD1 resistant lesion harbored a distinct immune cell niche, however, anti-PD1 resistant tumors were generally immune poor with non-expanded TCR clones. Such immune poor microenvironments were associated with melanoma cells having a de-differentiated phenotype lacking expression of MHC-I molecules. In addition, anti-PD1 resistant tumors had reduced fractions of PD1+ CD8+ T cells as compared to ICB naïve metastases. Collectively, these data show the complexity of ICB resistance and highlight differences between anti-CTLA4 and anti-PD1 resistance that may underlie differential clinical outcomes of therapy sequence and combination.
Project description:Background: Outcomes for locally advanced or recurrent/ metastatic head and neck squamous cell carcinomas (HNSCCs) remain unfavorable despite recent advances with immune checkpoint blockade (ICB). Preclinical studies using model antigens identified a critical role of CD8+TCF7+PD1+ T cells in anti-PD1 response. Studies on the heterogeneity and clonal dynamics of global tumor infiltrating T lymphocytes (TILs) in the HNSCC anti-PD1 and anti-CTLA4 response have not been explored. Results: In this study, we generated isogenic HNSCC anti-PD1 sensitive/resistant models that bore distinct cancer cell intrinsic transcriptomic programs. Tumor microenvironment characterization using mass cytometry and targeted depletion revealed the contribution of Tregs and M2-like macrophages in anti-PD1 resistance. Paired single-cell RNA and TCR sequencing on tumor infiltrating immune cells from ICB responsive and resistant HNSCC models identified a spectrum of CD8+ TIL subsets including TCF7+PD1- (naïve/memory-like), TCF7+PD1+ (progenitor exhausted), and TCF7-PD1+ (terminally exhausted). Mapping TCR shared fractions between these subsets identified that successful anti-PD1 or anti-CTLA4 therapy induced higher post-treatment T cell lineage transitions. A TIL differentiation gene signature was associated with better responses in multiple ICB clinical trials. Conclusions: Together, analyses integrating scRNAseq and TCRseq demonstrate distinct differentiation dynamics of CD8+ TILs in novel ICB responsive and resistant HNSCC models, highlighting critical aspects of CD8+ TIL differentiation in response to ICB.
Project description:Treatment with immunotherapy, particularly immune checkpoint blockade, can lead to benefit in the clinical setting. However, many preclinical and clinical studies suggest that resistance to anti-PD1 treatment frequently occurs, resulting in tumor relapse and treatment failure in cancer including hepatocellular carcinoma (HCC) patients. In this study ,10 HCC patients were treated with anti-PD1, and the biopsy samples before treatment were used for 289 nanostring panel RNA sequencing to compare responding and non-responding tumors to find possible pretreatment biomarkers or targets of the anti-PD1 therapy response
Project description:A previously established bioassay using Jurkat cells overexpressing PD1 and Lag3 allowed for assessment of simultaneous blockade of PD1 and LAG3 pathways in an in-vitro setting and demonstrated that an antibody cocktail increased IL-2 levels 5-fold better than single agent treatment. To gain understanding of signal transduction events RNA-Seq analysis of cell pellets individually treated with LAG3 or PD1 antibodies was used to reveal modest immune activation however, 5-fold more genes were upregulated upon combination treatment. There were increases in costimulatory genes like CD28, CD5, CD6 as well as other intracellular signaling molecules like LCP2 and ITK. Given the role of ERK in immune activation of T cells, pERK levels of Jurkat cells in the assay were evaluated, indicating that ERK phosphorylation was impacted on PD1 and LAG3 engagement with their ligands and this could be reversed by antibody blockade. A small molecule phosphatase inhibitor NSC87877, when combined with the PD1 antibody, could phenocopy the effect of combining PD1 and LAG3 blocking antibodies. CD28 has a recognized role in PD1 signaling but the impact on LAG3 signaling remains unknown. CD28 knockout cells demonstrated an overall muted IL-2 response but retained combination benefit in terms of IL-2 production in the context of LAG3 and PD1 co-blockade versus individual antibody treatments. Taken together, these observations provide new insights on the impact of LAG3 and PD1 co-blockade and provides additional support for ongoing immunotherapy clinical trials that combine PD1 and LAG3 antibodies.
Project description:PTEN deficiency is known to lead to tumor-intrinsic resistance to immune checkpoint blockade (ICB) treatment, especially in glioblastoma (GBM). We used RNA sequence to study the global gene expression and identified differentially expressed genes in PTEN knockdown GL261 cells, aiming to identify genes and pathways that are regulated by PTEN.
Project description:Griffin GK, Wu J, Iracheta-Vellve A, Patti JC, Hsu J, Davis T, Dele-Oni D, Du PP, Halawi A, Ishizuka JJ, Kim S, Klaeger S, Knudsen NH, Miller BC, Nguyen T, Olander K, Papanastasiou M, Rachimi S, Robitschek EJ, Schneider EM, Yeary M, Zimmer M, Jaffe JD, Carr SA, Doench JG, Haining WN, Yates KB, Manguso RT, Bernstein BE. 2020. Epigenetic dysregulation is a defining feature of tumorigenesis and has been implicated in immune escape, yet mechanisms that drive immune evasion are poorly understood. To systematically identify epigenetic factors that modulate the immune sensitivity of tumor cells, we performed in vivo CRISPR-Cas9 screens targeting 936 chromatin regulators in mouse tumor models treated with immune checkpoint blockade. We identified the H3K9-methyltransferase SETDB1 and other members of the HUSH and KAP1 complexes as cell-intrinsic mediators of immune escape in tumor cells. We also found that amplification of SETDB1 (1q21) in human tumors is associated with reduced cytotoxic T-cell infiltration and resistance to immune checkpoint blockade. Mechanistically, we demonstrate that SETDB1 represses broad domains, hundreds of kilobases in size, many of which reside within the open genome compartment. These SETDB1 domains are enriched for transposable elements (TEs) and immune gene clusters associated with segmental duplication events, a central mechanism of mammalian genome evolution. SETDB1 loss derepresses latent TE-encoded regulatory elements and proximal immune genes within these repetitive regions, including canonical co-stimulatory ligands, and induces hundreds of putative TE-encoded viral antigens. Our study establishes SETDB1 as an epigenetic checkpoint that suppresses intrinsic immunogenicity in cancer cells, and thus represents a candidate target for immunotherapy.
Project description:Although multiple studies have investigated the biomarkers of response to immune checkpoint blockade (ICB), the significance of each biomarker varies across clinical cohorts independent of cancer type. It remains unclear whether primary ICB response and resistance is encoded in the cancer cells (cancer-intrinsic) or driven by the immune microenvironment unique to each host (cancer-extrinsic). To answer this question, we established a unique mouse system that utilizes clonal tracing and mathematical modeling to uncouple the cancer-intrinsic and -extrinsic mechanisms of ICB resistance. We found that tumors with the same clonal constitution show heterogeneous ICB response in different hosts. Primary resistance is associated with the cancer-extrinsic immune microenvironment rather than proliferation of intrinsically ICB-resistant cancer cells. Instead, pre-existing cancer-intrinsic ICB-resistant clones with distinct transcriptional and epigenetic profiles were enriched in responders. We further identified two gene expression signatures associated with cancer-intrinsic resistance, including increased interferon response genes and glucocorticoid response genes. Our findings are supported by experiments in another mouse model and clinical data from multiple ICB treatment cohorts. Our study emphasizes the importance of optimal microenvironment in cancer immunotherapy, and implicates the value of immunotherapy biomarkers that account for both cancer-intrinsic and -extrinsic mechanisms of resistance.