Project Funding Details

The rational development of new therapeutic combinations addressing the resistance to immune checkpoint blockade (ICB) therapy is a clinical need to improve the management of metastatic melanoma patients. Several pieces of evidence identified that strategies increasing the antigen presentation and interfering with the detrimental crosstalk between the tumor cells and those of the surrounding tumor immune microenvironment (TIME), significantly improve the ICB response. BH3 mimetics, small molecules able to interfere with the function of Bcl-2 family anti-apoptotic proteins, have gained excitement with the recent success in hematological malignancies. Their antitumor efficacy, when administered alone or in combination with chemo- or targeted- therapy, has been characterized in different preclinical solid models, and clinical trials are evaluating the safety and efficacy of BH3 mimetics in combination regimens in solid tumors, including melanoma. Our preliminary results indicate that Bcl-2 inhibition may increase the expression and the membrane exposure of MHC I and some molecules belonging to the antigen-presenting machinery, and could potentiate the ICB treatment. The anti-apoptotic members of the Bcl-2 family, particularly Bcl-2, could elude the immune surveillance of melanoma by acting on both tumor cells and those of the TIME. Bcl-2 inhibition may increase melanoma immunogenicity, thus potentiating the efficacy of ICB therapy. This project aims to investigate whether Bcl-2 inhibition can: i) increase the melanoma immunogenicity by regulating the MHC I molecules and the antigen diversity, and modulating the extracellular vesicles (EVs) release and content; ii) affect the tumor-infiltrating immune cell subpopulations and their activation; iii) potentiate the immunotherapy treatment in ICB-resistant melanoma models. A panel of established murine and human melanoma cell lines, and patient-derived metastatic melanoma cells will be used for the in vitro experiments. The ability of Bcl-2 inhibition (through genetic or pharmacological approaches) to regulate the expression levels or the functionality of MHC I molecules or those of the antigen-presenting machinery will be investigated together with the involved molecular mechanisms. Proteomic analysis will be used to identify the ability of Bcl-2 inhibition to regulate the peptide repertoire generated by melanoma cells. EVs isolated by conditioned media from melanoma cells with different levels of Bcl-2 obtained through genetic or pharmacological approaches and from plasma samples of tumor-bearing mice treated with BH3 mimetics will be analyzed to evaluate the ability of Bcl-2 inhibition to modulate EVs assembly, release, and content. In vivo, low or highly immunogenic murine melanoma models will be used to analyze the ability of Bcl-2 inhibitors (ABT-199, ABT-263) to modulate the recruitment and activation of immune cell subsets, potentiate the efficacy of ICB therapy and overcome ICB resistance. Finally, the antitumor efficacy of the combinatorial regimen will be evaluated by using patient-derived organotypic cultures from metastatic melanoma patients. We expect to develop new Bcl-2-based therapeutic strategies to address the ICB resistance and to identify novel functions of the Bcl-2 family in mediating the crosstalk between melanoma cells and those of the TIME. Targeting the Bcl-2 family members may provide an alternative way to increase melanoma immunogenicity and improve the response to ICB therapy.