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Tissue-specific tumor microenvironments influence responses to immunotherapies.

ABSTRACT: Objectives:Investigation of variable response rates to cancer immunotherapies has exposed the immunosuppressive tumor microenvironment (TME) as a limiting factor of therapeutic efficacy. A determinant of TME composition is the tumor location, and clinical data have revealed associations between certain metastatic sites and reduced responses. Preclinical models to study tissue-specific TMEs have eliminated genetic heterogeneity, but have investigated models with limited clinical relevance. Methods:We investigated the TMEs of tumors at clinically relevant sites of metastasis (liver and lungs) and their impact on αPD-1/αCTLA4 and trimAb (αDR5, α4-1BB, αCD40) therapy responses in the 67NR mouse breast cancer and Renca mouse kidney cancer models. Results:Tumors grown in the lungs were resistant to both therapies whereas the same tumor lines growing in the mammary fat pad (MFP), liver or subcutaneously could be completely eradicated, despite greater tumor burden. Assessment of tumor cells and drug delivery in 67NR lung or MFP tumors revealed no differences and prompted investigation into the immune TME. Lung tumors had a more immunosuppressive TME with increased myeloid-derived suppressor cell infiltration, decreased T cell infiltration and activation, and decreased NK cell activation. Depletion of various immune cell subsets indicated an equivalent role for NK cells and CD8+ T cells in lung tumour control. Thus, targeting T cells with αPD-1/αCTLA4 or trimAb was not sufficient to elicit a robust antitumor response in lung tumors. Conclusion:Taken together, these data demonstrate that tissue-specific TMEs influence immunotherapy responses and highlight the importance in defining tissue-specific response patterns in patients.

SUBMITTER: Oliver AJ

PROVIDER: S-EPMC6869967 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Purpose: Next-generation sequencing (NGS)-derived transcriptome profiling (RNA-seq) is a powerful tool for analysing cellular pathways involved in treatment responses. In this study, RNA-seq was used to perform differential gene expression (DEG) and gene ontology (GO) analyses in prostate tumors treated with different immunotherapies and their combination. This was in order to investigate which pathways are activated and mediate the therapeutic effect. Methods: Mice with TRAMP-C2 subcutaneous prostate tumors were treated with either HBSS (control) or cyto-IL-15 or the STING agonist ADU-S100 or combination of ADU-S100 and cyto-IL-15. At day 6, tumors were removed and RNA was harvested to be used for RNA sequencing with Illumina NovaSeq. Using DESeq2, a comparison of gene expression between the treatment cohorts was performed and the Wald test was used to generate p-values and Log2 fold changes. GO analysis was performed on the statistically significant genes by implementing GeneSCF software using Fisher exact test. The mgi GO list was used to cluster the set of genes based on their biological process. Results: DEG analysis shown that more than 1,000 genes were differentially expressed in tumors 6 days after treatment with ADU-S100 or its combination with cyto-IL-15 (1,040 genes for ADU-S100 compared to control; 1,141 genes for combination compared to control). Most of the differentially expressed genes were upregulated (>70% in both comparisons). cyto-IL-15 led to differential expression of 96 genes compared to control. Differential expressed genes included Cxcl11 involved in immune cell recruitment and activation, and genes encoding granzymes a and b, which are proteases released by cytotoxic T cells and natural killer (NK) cells to kill cancer cells. In the control versus ADU-S100 or combination comparisons, GO analysis revealed that the majority of genes were involved in processes such as cellular responses to interferon-γ and β, complement activation, innate immune response, phagocytosis, and B cell signalling and activation. Conclusions: This study provides valuable insights in differential expression and activation of genes and cellular pathways involved in eliciting responses to immunotherapies in mouse prostate tumors. Using NSG and more specifically RNAseq-based transcriptome characterization, a detailed quantitative and qualitative analysis on how novel therapies exert their efficacy in tumors can be achieved and uncover the specific biological processes and functions contributing to the anti-tumor effects.

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Tissue-specific tumor microenvironments influence responses to immunotherapies.

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