Phd in INNOVATIVE BIOMEDICAL TECHNOLOGIES IN CLINICAL MEDICINE

Thesis title: Functional inhibition of ERAAP as a new strategy to induce protective antitumor immunity in Neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid tumor in pediatrics and account for 15% of childhood cancer-related mortality. Despite advanced and intensive multidisciplinary therapeutic approaches, the overall mortality of patients with high-risk (HR) NB remains significant. The presence of immune cells in the NB microenvironment has been correlated with favorable clinical outcomes. Therefore, the identification of new therapies aimed at converting the immunosuppressive environment into an immunostimulatory one should represent an important strategy for the treatment of HR-NB patients. Several studies have highlighted the potential role of the endoplasmic reticulum (ER) aminopeptidase 1 (ERAP1) and its murine homologue ERAAP in reprogramming the immunogenicity of cancer cells. ERAP1 is a multifunctional zinc metallopeptidase crucial for the maturation of a wide spectrum of substrates by trimming amino acid residues at the Nterminus of precursor peptides. In ER, ERAP1 participates in the generation of peptides presented by MHC class I molecules on the cell surface. ERAP1 inhibition results in an alteration of the normal immunopeptidome with the consequent stimulation of a potent immune response mediated by both NK cells and CD8+ T lymphocytes. The aim of the present project is to study the potential immunotherapeutic effect of the ERAP1 in NB. To this end, we have shown that the knockout of the murine homologue of ERAP1, ERAAP, makes murine NB cells more susceptible to immune cell-mediated lysis and induces the release of IFNγ and TNFα by both NK cells and CD8+ T cells. Accordingly, murine-derived organotypic tumor spheroids (MDOTS) treated with selected ERAAP inhibitors recall more immune cells by promoting the activation of both CD8+ T cells and NK cells. Furthermore, we found that genetic inhibition of ERAAP controls tumor growth in immunocompetent mice only at early stages. These results indicate that ERAAP is a prototype of a new class of molecules capable of inducing immunogenicity. Our data suggest that a combinatorial approach based on the immunomodulatory effect mediated by ERAAP inhibition and the creation of an immunityfriendly environment could represent a promising strategy to induce an antitumor immune response in NB.