Nuovi Approcci Terapeutici Per Il Trattamento Dell'Osteosarcoma

Osteosarcoma has been the subject of extensive investigation over the last decades; nevertheless, therapeutic options for this disease remain limited, and clinical outcomes have shown little improvement, particularly in metastatic and relapsed patients. As will be discussed in Chapter 2, this lack of progress is not due to insufficient knowledge, but rather to the intrinsic biological complexity of osteosarcoma, which is characterised by marked genomic instability, early metastatic spread, and a tumour microenvironment that actively supports disease progression and therapeutic resistance. In this context, the present PhD thesis is aiming at exploring alternative and biologically informed strategies that may help overcome some of the current limitations of standard treatment. Chapter 3 focuses on the evaluation of osteoblast-derived extracellular vesicles as carriers for conventional chemotherapeutic drugs. By loading these vesicles with methotrexate, doxorubicin, and cisplatin, we investigate whether this approach can improve drug selectivity and antitumour efficacy toward osteosarcoma cells, while reducing side effects on normal bone cells, both in vitro and in vivo. In Chapter 4, we shift attention to the molecular communication between tumour cells and their surrounding microenvironment, analysing next-generation sequencing data through bioinformatic approaches to identify signalling pathways and transcriptional programs involved in inflammation, extracellular vesicle–mediated communication, and tumour–stroma interactions. The impact of tumour-derived signals on bone cells is further addressed in Chapter 5, which examines the phenotypic effects of the osteosarcoma secretome on osteoblast function, including alterations in metabolism, differentiation, and matrix production, based on previously published work. Finally, Chapter 6 summarizes the main conclusions of this PhD thesis and provides a critical discussion of the literature, highlighting future perspectives and the potential relevance of these findings for the development of more effective therapeutic approaches for osteosarcoma.