Project description:Immune checkpoint therapy has improved outcome of patients with advanced melanoma, however the tumor becomes refractory in a large number of patients. Therefore, novel combination therapies that enhance anti-melanoma immunity are highly desirable. We studied the impact of MDM2 (mouse double minute 2) inhibition, leading to p53 activation, on response to anti-PD-1 immunotherapy in melanoma. MDM2 treatment caused upregulation of MHC II and IL-15 in melanoma cells in a p53 dependent manner. Survival of melanoma bearing mice improved upon combining anti-PD1 and MDM2 inhibition in vivo. Lack of IL-15Rα in T cells abrogated the beneficial effect of the combined treatment. This gene expression study was performed to determine potential effects of MDM2 inhibition on genes in the melanoma microenvironment.
Project description:We performed single-cell RNA-sequencing of tumor immune infiltrates and matched peripheral blood mononuclear cells of checkpoint inhibitor (CPI)-naive stage III-IV metastatic melanoma patients. After sample collection, the same patients received CPI-treatment and their response was assessed.
Project description:High-grade serous ovarian cancer (HGSC) accounts for the vast majority (>70%) of ovarian cancer-associated deaths with minor therapeutic improvements. Among four proposed molecular subtypes of HGSC, the C5 subtype is distinguished by high proliferative potential and elevated immune evasion which is indicated by an unfavorable MHCI/PD-L1 ratio. However, the underlying key drivers of the C5 subtype remained elusive. Here we identify oncofetal RNA-binding proteins (RBPs) promoting the immune evasion of C5-HGSC. The IGF2 mRNA binding protein 1 (IGF2BP1) enhances expression of the E3 ligase MDM2, which induces degradation of IRF1 resulting in reduced MHCI presentation. Concomitantly, IGF2BP1 elevates PD-L1 synthesis by impairing its microRNA-directed silencing. This shifts the intra-tumoral MHCI/PD-L1 ratio, limits immune cell infiltration, and promotes evasion of tumor cells from cytotoxic T cells (CTLs) in human and syngeneic mouse models of ovarian cancer. The small molecule inhibitor BTYNB impairs IGF2BP1-directed regulation of MHCI/PD-L1 ratios, promotes CTL-directed killing as well as activation, and strongly synergizes with immune checkpoint inhibition (ICI) by Nivolumab in vitro and in vivo.
Project description:High-grade serous ovarian cancer (HGSC) accounts for the vast majority (>70%) of ovarian cancer-associated deaths with minor therapeutic improvements. Among four proposed molecular subtypes of HGSC, the C5 subtype is distinguished by high proliferative potential and elevated immune evasion which is indicated by an unfavorable MHCI/PD-L1 ratio. However, the underlying key drivers of the C5 subtype remained elusive. Here we identify oncofetal RNA-binding proteins (RBPs) promoting the immune evasion of C5-HGSC. The IGF2 mRNA binding protein 1 (IGF2BP1) enhances expression of the E3 ligase MDM2, which induces degradation of IRF1 resulting in reduced MHCI presentation. Concomitantly, IGF2BP1 elevates PD-L1 synthesis by impairing its microRNA-directed silencing. This shifts the intra-tumoral MHCI/PD-L1 ratio, limits immune cell infiltration, and promotes evasion of tumor cells from cytotoxic T cells (CTLs) in human and syngeneic mouse models of ovarian cancer. The small molecule inhibitor BTYNB impairs IGF2BP1-directed regulation of MHCI/PD-L1 ratios, promotes CTL-directed killing as well as activation, and strongly synergizes with immune checkpoint inhibition (ICI) by Nivolumab in vitro and in vivo.
Project description:Immune checkpoint inhibitors (ICIs) have transformed the treatment of melanoma. However, the majority of patients have primary or acquired resistance to ICIs, limiting durable responses and patient survival. Interferon-gamma (IFNg) signaling and the expression of IFNg-stimulated genes correlate with either response or resistance to ICIs, in a context-dependent manner. While IFNg-inducible immunostimulatory genes are required for response to ICIs, chronic IFNg signaling induces the expression of immunosuppressive genes, promoting resistance to these therapies. Here, we show that high levels of ULK1 correlate with poor survival in melanoma patients and overexpression of ULK1 in melanoma cells enhances IFNg-induced expression of immunosuppressive genes, with minimal effects on the expression of immunostimulatory genes. In contrast, genetic or pharmacological inhibition of ULK1 reduces expression of IFNg-induced immunosuppressive genes. ULK1 binds IRF1 in the nuclear compartment of melanoma cells, controlling its binding to the PD-L1 promoter region. Additionally, pharmacological inhibition of ULK1 in combination with anti-PD-1 therapy further reduces melanoma tumor growth and enhances anti-tumor immune responses in vivo. Our data suggest that targeting ULK1 represses IFNg-dependent immunosuppression. These findings support the combination of ULK1 drug-targeted inhibition with ICIs for the treatment of melanoma patients to improve response rates and patient outcomes.
Project description:Immune checkpoint blockade (ICB) has revolutionized melanoma therapy, but drug resistance represents a significant limitation. Here we utilize a platform incorporating transcriptomic profiling, high-throughput drug screening (HTDS) and murine models to demonstrate the pre-clinical efficacy of cobimetinib and regorafenib (termed Cobi+Reg) for ICB-resistant melanoma. RNA-Sequencing (RNA-Seq) analysis of ICB-resistant melanomas demonstrated activation of several targetable pathways. HTDS targeting these pathways identified several effective combinations in ICB-resistant patient-derived xenograft (PDX) models. Cobi+Reg emerged as the most promising regimen, with efficacy against distinct molecular melanoma subtypes and following progression on ICB in immunocompetent models. RNA-Seq analysis of Cobi+Reg-treated tumors demonstrated upregulation of antigen presentation machinery, with concomitantly increased activated T cell infiltration. Combining Cobi+Reg with ICB was superior to either treatment in vivo. This analytical platform has identified several effective combinations, presenting Cobi+Reg as a rational therapeutic strategy either following resistance to or combined with ICB for advanced melanoma.
Project description:High-grade serous ovarian cancer (HGSC) accounts for the vast majority (>70%) of ovarian cancer-associated deaths with minor therapeutic improvements. Among four proposed molecular subtypes of HGSC, the C5 subtype is distinguished by high proliferative potential and elevated immune evasion which is indicated by an unfavorable MHCI/PD-L1 ratio. However, the underlying key drivers of the C5 subtype remained elusive. Here we identify oncofetal RNA-binding proteins (RBPs) promoting the immune evasion of C5-HGSC. The IGF2 mRNA binding protein 1 (IGF2BP1) enhances expression of the E3 ligase MDM2, which induces degradation of IRF1 resulting in reduced MHCI presentation. Concomitantly, IGF2BP1 elevates PD-L1 synthesis by impairing its microRNA-directed silencing. This shifts the intra-tumoral MHCI/PD-L1 ratio, limits immune cell infiltration, and promotes evasion of tumor cells from cytotoxic T cells (CTLs) in human and syngeneic mouse models of ovarian cancer. The small molecule inhibitor BTYNB impairs IGF2BP1-directed regulation of MHCI/PD-L1 ratios, promotes CTL-directed killing as well as activation, and strongly synergizes with immune checkpoint inhibition (ICI) by Nivolumab in vitro and in vivo.
Project description:Melanoma is one of the tumor types with the highest risk of brain metastasis. However, the biology of melanoma brain metastasis and the contribution of the brain immune microenvironment to the responses to therapies remain insufficiently characterized. By using preclinical models and single-cell transcriptomics, we identify a mechanism to promote antitumor immunity in melanoma brain metastasis. We show that activation of the Rela/NF-kB pathway in microglia promotes melanoma brain metastasis and that targeting this pathway elicits microglia reprogramming towards a proinflammatory phenotype that enhances antitumor immunity and reduces brain metastatic burden. Additionally, proinflammatory microglial markers in melanoma brain metastasis correlate with better responses to immune checkpoint inhibitors in patients and we show that Rela/NF-kB targeting improves responses to these therapies in the brain. Thus, we propose targeting Rela/NF-kB in activated microglia as a strategy to promote antitumor immunity and responses to immune checkpoint inhibitors in melanoma brain metastasis.
Project description:Melanoma is one of the solid tumor types with the highest risk of brain metastasis. However, the biology of melanoma brain metastasis and the contribution of the brain immune microenvironment to the responses to therapies remain insufficiently characterized. By using preclinical models and single-cell transcriptomics, we identify microglia, as critical regulators of melanoma biology in the brain. We show that activation of the Rela/NF-kB pathway in microglia promotes melanoma brain metastasis and that targeting this pathway elicits microglia reprogramming towards a pro-inflammatory phenotype that enhances anti-tumor immunity and reduces brain metastatic burden. Additionally, canonical and pro-inflammatory microglial markers in melanoma brain metastasis correlate with better responses to immune checkpoint inhibitors in patients and we show that Rela/NF-kB targeting improves responses to these therapies in the brain. Thus, we propose targeting Rela/NF-kB in activated microglia as a strategy to promote anti-tumor immunity and to improve the response to immune checkpoint inhibitors in melanoma brain metastasis.