Project description:BET-Bromodomain Inhibitors Engage The Host Immune System And Regulate Expression Of The Immune Checkpoint Ligand PD-L1 [EuMyc_RNA-seq]
Project description:Cancer treatment has been revolutionized by immune checkpoint inhibitors, which regulate immune cell function by blocking the interactions between immune checkpoint molecules and their ligands. The interaction between programmed cell death-1 (PD-1) and programmed cell death-ligand 1 (PD-L1) is a target for immune checkpoint inhibitors. Nanobodies, which are recombinant variable domains of heavy-chain-only antibodies, can replace existing immune checkpoint inhibitors, such as anti-PD-1 or anti-PD-L1 conventional antibodies. However, the screening process for high-affinity nanobodies is laborious and time-consuming. Here, we identified high-affinity anti-PD-1 nanobodies using peptide barcoding, which enabled reliable and efficient screening by distinguishing each nanobody with a peptide barcode that was genetically appended to each nanobody. We prepared a peptide-barcoded nanobody (PBNb) library with thousands of variants. Three high-affinity PBNbs were identified from the PBNb library by quantifying the peptide barcodes derived from high-affinity PBNbs. Furthermore, these three PBNbs neutralized the interaction between PD-1 and PD-L1. Our results demonstrate the utility of peptide barcoding and the resulting nanobodies can be used as experimental tools and antitumor agents. Peptide barcoding can be used to screen for molecules other than nanobodies. Our methods, such as the design of peptide barcodes, the design of peptide-barcoded molecules, preparation of peptide-barcoded molecule library, and quantification of peptide barcodes, are helpful in screening for peptide-barcoded molecules.
Project description:BET inhibitors (BETi) target bromodomain-containing proteins and are currently being evaluated as anti-cancer agents. We discovered that the maximal therapeutic effects of BETi in a Myc-driven B cell lymphoma model required an intact host immune system. Genome-wide analysis of the BETi induced transcriptional response identified the immune checkpoint ligand Cd274 (Pd-l1) as a Myc-independent, BETi target-gene. BETi directly repressed constitutively expressed and IFN-γ induced CD274 expression across different human and mouse tumor cell lines and primary patient samples. Mechanistically, BETi decreased Brd4 occupancy at the Cd274 locus without any change in Myc occupancy, resulting in transcriptional pausing and rapid loss of Cd274 mRNA production. Finally, targeted inhibition of the PD1/PD-L1 axis by combining anti-PD1 antibodies and the BETi JQ1 caused synergistic responses in mice bearing Myc-driven lymphomas. Our data uncovers a novel interaction between BETi and the PD-1/PD-L1 immune-checkpoint and provides novel insight into the transcriptional regulation of CD274.
Project description:BET inhibitors (BETi) target bromodomain-containing proteins and are currently being evaluated as anti-cancer agents. We discovered that the maximal therapeutic effects of BETi in a Myc-driven B cell lymphoma model required an intact host immune system. Genome-wide analysis of the BETi induced transcriptional response identified the immune checkpoint ligand Cd274 (Pd-l1) as a Myc-independent, BETi target-gene. BETi directly repressed constitutively expressed and IFN-γ induced CD274 expression across different human and mouse tumor cell lines and primary patient samples. Mechanistically, BETi decreased Brd4 occupancy at the Cd274 locus without any change in Myc occupancy, resulting in transcriptional pausing and rapid loss of Cd274 mRNA production. Finally, targeted inhibition of the PD1/PD-L1 axis by combining anti-PD1 antibodies and the BETi JQ1 caused synergistic responses in mice bearing Myc-driven lymphomas. Our data uncovers a novel interaction between BETi and the PD-1/PD-L1 immune-checkpoint and provides novel insight into the transcriptional regulation of CD274.
Project description:BET inhibitors (BETi) target bromodomain-containing proteins and are currently being evaluated as anti-cancer agents. We discovered that the maximal therapeutic effects of BETi in a Myc-driven B cell lymphoma model required an intact host immune system. Genome-wide analysis of the BETi induced transcriptional response identified the immune checkpoint ligand Cd274 (Pd-l1) as a Myc-independent, BETi target-gene. BETi directly repressed constitutively expressed and IFN-γ induced CD274 expression across different human and mouse tumor cell lines and primary patient samples. Mechanistically, BETi decreased Brd4 occupancy at the Cd274 locus without any change in Myc occupancy, resulting in transcriptional pausing and rapid loss of Cd274 mRNA production. Finally, targeted inhibition of the PD1/PD-L1 axis by combining anti-PD1 antibodies and the BETi JQ1 caused synergistic responses in mice bearing Myc-driven lymphomas. Our data uncovers a novel interaction between BETi and the PD-1/PD-L1 immune-checkpoint and provides novel insight into the transcriptional regulation of CD274.
Project description:Epigenetic regulators have emerged as exciting targets for cancer therapy. Additionally, restoration of antitumor immunity by blocking the PD-L1 signaling using antibodies has proven to be beneficial in cancer therapy. Here we show that BET bromodomain inhibition suppresses PD-L1 expression and restores antitumor immunity in ovarian cancer. CD274 (encoding PD-L1) is a direct target of BRD4-mediated gene transcription. In mouse models, treatment with the BET inhibitor JQ1 significantly reduced PD-L1 expression on tumor cells and tumor-associated dendritic cells and macrophages, which correlated with an increase in the activity of antitumor cytotoxic T cells. Together, these data demonstrate an epigenetic approach to block PD-L1 signaling to restore antitumor immunity. Given the fact that BET inhibitors have been proven safe with manageable reversible toxicity in clinical trials, our findings indicate that pharmacological BET inhibitors represent a novel treatment strategy for targeting PD-L1 expression.
Project description:Programmed death-ligand 1 (PD-L1) expression has been associated with response to PD-1/PD-L1 inhibition, but responses are also seen in patients with PD-L1 negative tumors when assessed immunohistochemically (IHC) with various antibodies. To help elucidate these findings, we performed a positron emission tomography (PET) imaging study in human with the anti-PD-L1 antibody atezolizumab labeled with Zirconium-89 (89Zr) prior to treatment with atezolizumab to assess normal tissue distribution and evaluate tumor tracer uptake. Additionally, to help explain why some patients respond to checkpoint inhibitors despite low or absent PD-L1 expression, we compared PD-L1 expression and immune phenotypes based on both CD8 IHC and RNA sequencing of post-tracer biopsies to tumor tracer uptake (SUVmax).
Project description:<p>Desmoplastic melanoma (DM) is a rare subtype of melanoma characterized by dense fibrous stroma, resistance to chemotherapy and a lack of actionable driver mutations, but is highly associated with ultraviolet light DNA damage. We analysed 60 patients with advanced DM treated with programmed cell death 1 (PD-1) or PD-1 ligand (PD-L1) blocking antibody therapy. Objective tumor responses were observed in 42 of the 60 patients (70%, 95% confidence interval 57-81%), including 19 patients (32% overall) with a complete response. Whole-exome sequencing revealed a high mutational load and frequent NF-1 mutations (14 out of 17 cases). Immunohistochemistry (IHC) analysis from 19 DM and 13 non-DM revealed a higher percentage of PD-L1 positive cells in the tumor parenchyma in DM (p = 0.04), highly associated with increased CD8 density and PD-L1 expression in the tumor invasive margin. Therefore, patients with advanced DM derive significant clinical benefit from PD-1/PD-L1 immune checkpoint blockade therapy despite being a cancer defined by its dense desmoplastic fibrous stroma. The benefit is likely derived from the high mutational burden and a frequent pre-existing adaptive immune response limited by PD-L1 expression.</p>