Project description:Disrupting PD-1/PD-L1 interaction rejuvenates antitumor immunity. Clinical successes by blocking PD-1/PD-L1 binding have grown across wide-ranging cancer histologies, but innate therapy resistance is evident in the majority of treated patients1. Cancer cells can express robust surface levels of PD-L1 to tolerize tumor-specific T cells, but regulation of PD-L1 protein levels in the cancer cell is poorly understood. Quasi-mesenchymal tumor cells up-regulate PD-L1/L2 and induce an immune-suppressive microenvironment, including expansion of M2-like macrophages and regulatory T cells and exclusion of CD8+ T-cell infiltration2. Targeted therapy, including MAPK inhibitor therapy in melanoma, leads to quasi-mesenchymal transitions and resistance3, and both MAPK inhibitor treatment and mesenchymal signatures are associated with innate anti-PD-1 resistance4,5. Here we identify ITCH as an E3 ligase that downregulates tumor cell-surface PD-L1/L2 in PD-L1/L2-high cancer cells, including MAPK inhibitor-resistant melanoma, and suppresses acquired MAPK inhibitor resistance in and only in immune-competent mice. ITCH interacts with and poly-ubiquitinates PD-L1/L2, and ITCH deficiency increases cell-surface PD-L1/L2 expression and reduces T cell activation. Mouse melanoma tumors grow faster with Itch knockdown only in syngeneic hosts but not in immune-deficient mice. MAPK inhibitor therapy induces tumor cell-surface PD-L1 expression in murine melanoma, recapitulating the responses of clinical melanoma3, and this induction is more robust with Itch knockdown. Notably, suppression of ITCH expression first elicits a shift toward an immune-suppressive microenvironment and then accelerates resistance development. These findings collectively identify ITCH as a critical negative regulator of PD-L1 tumor cell-surface expression and provide insights into previously unexplained role of PD-L1 in adaptive resistance to therapy.
Project description:Colo-rectal cancer is still one of the leading causes of cancer death worldwide. In France, approximately 40 500 new cases are diagnosed each year. With more than 17 500 deaths in France in 2011, colo-rectal cancer is responsible for more than 12% of all cancer deaths, the overwhelming of deaths occurring in patients with metastatic disease.
Many studies highlight the fact that colo-rectal cancer has immunogenic properties and that host immune responses can influence survival. Recent data have provided a clearer understanding of the factors limiting the antitumor immune response in colo-rectal cancer. One of the most critical checkpoint pathways responsible for mediating tumor-induced immune suppression is the programmed death-1 (PD-1) and PD ligand 1 (PD-L1) pathway.
PD-1 is expressed on activated immune cells and can link to PD-L1 express on Antigen-Presenting-Cell. Usually, this pathway is involved in promoting T-cells tolerance and preventing tissue damage in settings of chronic inflammation. In pathological context, the PD-1/PD-L1 pathway contributes to immune suppression and evasion. Many human solid tumors including colo-rectal cancer express PD-L1, and this expression is associated with a worse prognosis. The interaction of PD-1 with the ligand PD-L1 inhibits T-cell proliferation, survival, and effectors functions; induces apoptosis of tumor-specific T cells; promotes the differentiation of CD4+ T cells into immunosuppressive regulatory T cells; and increases the resistance of tumor cells to cytotoxic T lymphocytes attack. Thus, the blockage of the PD-1/PD-L1 interactions represents a logical target for cancer immunotherapy and in particular colo rectal cancer immunotherapy strategy.
Preclinical studies have shown that PD-L1 blockade improves the immune response by restoring T-cell effectors functions. Recent work in two in vivo tumor models shows a strong interest in using an anti-PD-L1 in combination with standard treatment of colo-rectal cancer (FOLFOX). In these models, the survival of mice that are treated with the combination therapy reached 40% when no mice were alive with FOLFOX treatment alone. This result may be explained, in one hand by cytotoxicity of 5FU and in the other hand by the restoration of anti-tumor immune activity of anti-PD-L1. These results suggest that the combination of chemotherapy with immunotherapy would act synergistically in patients with colo-rectal cancer.
Research Hypothesis: Combination of chemotherapy (FOLFOX) with immunotherapy association (anti-PD-L1 + anti-CTLA-4) would act synergistically in patients with colo-rectal cancer.
Project description:The cell-autonomous balance of immune-inhibitory and -stimulatory signals is a critical process in cancer immune evasion. Using patient-derived co-cultures, humanized mouse models, and single cell RNA-sequencing of patient melanomas biopsied before and on immune checkpoint blockade, we find that intact cancer-cell-intrinsic expression of CD58 and ligation to CD2 is required for anti-tumor immunity and is predictive of treatment response. Defects in this axis promote immune evasion through diminished T cell activation, impaired intratumoral T cell infiltration and proliferation, and concurrently increased PD-L1 protein stabilization. Through CRISPR-Cas9 and proteomics screens, we identify and validate CMTM6 as critical for CD58 maintenance and upregulation of PD-L1 upon CD58 loss. Competition by CD58 and PD-L1 for CMTM6 (via both extracellular loop domains) determines their rate of endosomal recycling over lysosomal degradation. Overall, we describe an underappreciated yet critical axis of cancer immunity and provide a molecular basis for how cancer cells balance immune inhibitory and stimulatory cues.
Project description:Antibodies and derivative drugs targeting immune checkpoints have been approved for the treatment of several malignancies, but there are fewer responses in patients with pancreatic cancer. Here, we designed a nanobody molecule with bi-targeting on PD-L1 and CXCR4, as both targets are overexpressed in many cancer cells and play important roles in tumorigenesis. The nanobody sequences targeting PD-L1 and CXCR4 were linked by the (G4S)3 flexible peptide to construct the anti-PD-L1/CXCR4 bispecific nanobody. The bispecific nanobody was expressed in E. coli cells and purified by affinity chromatography. The purified nanobody was biochemically characterized by mass spectrometry, Western blotting and flow cytometry to confirm the molecule and its association with both PD-L1 and CXCR4. The biological function of the nanobody and its anti-tumour effects were examined.
Project description:Cancer cells express high levels of PD-L1, a ligand of the PD-1 receptor on T cells, allowing tumors to suppress T cell activity 1-3. Clinical trials utilizing monoclonal antibodies that disrupt the PD-1/PD-L1 immune checkpoint have yielded remarkable results, with PD-1 immunotherapy approved as a first-line therapy for human lung cancer patients 4-6. Despite significant progress in targeting this pathway, the mechanisms through which PD-L1 is upregulated in non-small cell lung cancer (NSCLC) and other tumor types remain incompletely understood. Here we used CRISPR-based screening to identify regulators of PDL1 in human lung cancer cells, revealing potent induction of PD-L1 levels upon disruption of the heme biosynthesis pathway. Impairment of heme production activates the integrated stress response (ISR), allowing bypass of inhibitory upstream open reading frames in the PD-L1 5¢ UTR, resulting in enhanced PD-L1 translation and suppression of anti-tumor immunity. We further demonstrated that ISR-dependent translation of PD-L1 requires the translation initiation factor EIF5B. EIF5B overexpression, which is frequent in human lung cancers and is associated with poor prognosis, is sufficient to induce PD-L1. These findings uncover a new mechanism of immune checkpoint activation and suggest novel targets for therapeutic intervention.
Project description:PD-1 ligation delimits immunogenic responses in T cells. However, the consequences of PD-L1 ligation in T cells are uncertain. We found that T cell expression of PD-L1 in cancer was regulated by tumor-antigen, microbial signals, and sterile inflammatory cues. PD-L1+ T cells exerted tumor-promoting tolerance via three distinct mechanisms: (i) Binding of PD-L1 induced STAT3-dependent back-signaling in CD4+ T cells preventing activation, reducing Th1-polarization, and directing Th17-differentiation. PD-L1 signaling also induced an anergic Tbet-IFNg- phenotype in CD8+ T cells and was equally suppressive compared to PD-1 signaling. (ii) PD-L1+ T cells restrained effector T cells via the canonical PD-L1-PD-1 axis and were sufficient to accelerate tumorigenesis even in the absence of endogenous PD-L1. (iii) PD-L1+ T cells engaged PD-1+ macrophages inducing an alternative M2-like program, which had crippling effects on adaptive anti-tumor immunity. Collectively, we demonstrate that PD-L1+ T cells have diverse tolerogenic effects on tumor immunity.
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:Modelling of anti-tumour immune response: Immunocorrective effect
of weak centimetre electromagnetic waves
O.G. Isaeva* and V.A. Osipov
Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna,
Moscow Region, Russia
We formulate the dynamical model for the anti-tumour immune response based on
intercellular cytokine-mediated interactions with the interleukin-2 (IL-2) taken into
account. The analysis shows that the expression level of tumour antigens on antigen
presenting cells has a distinct influence on the tumour dynamics. At low antigen
presentation, a progressive tumour growth takes place to the highest possible value.
At high antigen presentation, there is a decrease in tumour size to some value when the
dynamical equilibrium between the tumour and the immune system is reached. In the
case of the medium antigen presentation, both these regimes can be realized depending
on the initial tumour size and the condition of the immune system. A pronounced
immunomodulating effect (the suppression of tumour growth and the normalization of
IL-2 concentration) is established by considering the influence of low-intensity
electromagnetic microwaves as a parametric perturbation of the dynamical system. This
finding is in qualitative agreement with the recent experimental results on
immunocorrective effects of centimetre electromagnetic waves in tumour-bearing mice.
Keywords: carcinogenesis; interleukin-2; modelling; anti-tumour immunity;
electromagnetic waves