Immunotherapy with immune checkpoint inhibitors (ICIs) has recently shown significant clinical efficacy with long term survival benefit in Non Small Cell Lung Cancer patients, although a main issue remains the high rate of failures. Significant efforts are directed to understand the mechanisms responsible for ICIs failures and to intervene on them in order to increase the proportion of responding patients. In this context there is mounting evidence that Cancer Stem Cells (CSCs) are by themselves weakly immunogenic. In addition, CSCs may contribute to the establishment of an immunosuppressive tumor micro-environment through their cross talk with protumorigenic cell types. Our laboratory has a multi- year expertise in the study of CSCs from adenocarcinoma of the lung. Major focus has been the demonstration that SCD1, the enzyme responsible of the synthesis of Monounsaturated Fatty Acids, plays an important role in lung CSCs propagation and survival, contributing to the activation of the beta-catenin and YAP/TAZ pathways. Our recent preliminary data suggest that lung CSCs hold an immune-evasive phenotype and that inhibiting both monounsaturated fatty acids and cholesterol synthesis, induces a pro-inflammatory and pro-immunogenic phenotype.
We hypothesize that a deeper understanding of the immune-evasive properties of lung adenocarcinoma CSCs and of their immune-suppressive pathways and analyze the patient risk factors (genetic susceptibility, poor diet, occupational exposures and air pollution may act independently or in concert with tobacco smoking in shaping the descriptive epidemiology of lung cancer genetic), as well as of CSCs ability to modify tumour micro-environment. Is needed because this may led to the identification of targets and pharmacological tools able to revert immune-evasion. Therefore, we believe that inhibition of lipid metabolic pathways could enhance immunogenicity of CSCs, likely improving ICI-based therapies.
Lung cancer is the leading cause of cancer related deaths with Non Small Cell Lung Cancer (NSCLC) accounting for 85% of all cases. At diagnosis most patients present with locally advanced or metastatic disease of which malignant pleural effusions (MPEs) represent a frequent complication. Immunotherapy with ICI has recently shown significant clinical efficacy with long term survival benefit in NSCLC patients. This has led to the approval of several agents either as first or second line therapy. However, a main issue remains the high rate of failures of response to ICI, which approximates 70% of cases. Treatment failures can be attributed to the presence of a subpopulation of cancer cells, defined cancer stem cells (CSCs), with the properties of extensive self-renewal, capability to generate differentiated cancer cells and resistance to therapies. A hallmark of tumour progression and recurrence is the ability to evade immune system, and CSCs might play an important role in this context. Growing evidences suggest that CSCs are by themselves weakly immunogenic and are not efficiently recognized and eliminated by the immune system. Indeed, several oncogenic signalling pathways may contribute to immune-evasion, as demonstrated for KRAS, one of the main mutated oncogene found in NSCLC. In addition, CSCs have been postulated to foster the creation of an immune evading microenvironment, through their cross talk with pro-tumorigenic cell types such as cancer associated fibroblasts and M2 macrophages, which is emerging as a critical element in limiting the efficacy of ICI therapy.Central to our project is the mounting evidence that cancer stem cells (CSC) are by themselves weakly immunogenic and therefore not efficiently recognized and eliminated by cells of the immune system. Cancer stem cells show low expression of one or more components of the antigen presentation machinery as well as low expression of T cell activation costimulatory molecules. CSCs can also create a microenvironment favorable to immune evasion through the secretion of immune regulatory soluble factors. Stabilized lung cancer cell lines and primary cell cultures derived from MPEs will be used to study the immunological, gene expression and metabolic properties of CSCs. Immune cells obtained from MPEs and from peripheral blood will be characterized and used in co-cultures with CSCs also using 3D organoids system. The interplay between immune response and metabolic pathways will be analyzed with the use of metabolic inhibitors. In vivo studies will be performed using "immunoavatars" in order to assess the effect of metabolic inhibitors in reverting immune evasion and to evaluate their synergism with checkpoint inhibitors. Deep characterization of the immune-evasive properties of lung cancer CSCs and identification of strategies to revert immuneevasion and to potentiate efficacy of immunotherapy.
This highly translational project will provide evidence that ICI immunotherapy in lung cancer can be enhanced by new combinations aimed at lipid metabolism in CSCs. Our data will generate new hypotheses to be tested in the clinic. The research plan therefore aims to better characterize the immunosuppressive properties of lung cancer stem cells and to assess whether the lipid metabolism of cancer could represent a possible strategy to enhance the immunogenicity of cancer. Future preventive efforts and research must focus on better understanding the risk factors that underlie lung carcinogenesis in nonsmokers. New approaches in the classification of lung cancer based on molecular techniques have begun to bring new insights to its etiology, particularly among non-smokers.Data obtained from all tasks will provide insights as to the prognostic value of the immune cell infiltrate and expression of immunomodulatory molecules with clinical outcome and allow to identify new markers and parameters that will be important for assessing patient responsiveness to the ICI therapy.
Moreover, data obtained from the genetic profiling of CSCs derived from MPEs compared to 2D counterparts, will allow to identify specific tumour mutations as well as possible neoantigens. These results will be fundamental for further studies directed to the generation of synthetic peptides that will be used to obtain CD8+ or CD4+ specific clones to functionally determine the recognition and response mechanism of CSCs, and also in the perspective of personalized medicine.Overall the proposed activities will be important in order to deciphering and understanding the mechanisms at the basis of the interaction between CSCs and immune system with the ultimate goal to develop approaches directed to enhance CSCs immunogenicity that are expected to synergize with ICI therapy, the analysis of these parameters along with the clinical parameters and clinical outcome could be important in order to individuate new prognostic factors.