Improve functionality and persistence of Chimeric Antigen Receptor redirected T cells in refractory/relapsed sarcoma patients by Beclin1 modulation

Substantial progress has been made in the treatment of paediatric patients affected by oncological malignancies over the past decades. However, children with high-risk, metastatic or relapsed disease continue to have poor prognosis despite aggressive multi-modal conventional therapies, which are associated with significant toxicity. In this scenario, paediatric sarcomas, which account for approximately 10% of all childhood solid malignant cancers, have the disadvantage to be indolent diseases with metastasises already at diagnosis and therefore more difficult to treat. In fact, the cure rates of localized disease are generally >70%, while the prognosis for children with disseminated, recurrent or refractory disease still maintains an unfavourable clinical outcome. For this reason, for this group of patients there is an urgent need to develop alternative, more efficient and less toxic therapies. The increasing understanding of tumour biology and the interaction between the tumour and the immune system led to the development of novel immune-based therapies, among which chimeric antigen receptor (CAR) T cells represent one of the more promising. CAR-T cells are genetically modified T cells that acquire specificity for selected cell surface antigens expressed by tumour cells promoting the recognition and elimination of malignant cells. Unlike conventional drugs, these cells can persist in our body for many years and re-activate, when they encounter tumour cells. Whereas dramatic responses have been observed in patients with B-cell malignancies, challenges to achieve similar results in other tumours are still considerable. It has been demonstrated that the limited efficacy of CAR-T cells, in these settings, is mainly due to the nature of these tumours and the presence of a hostile tumour microenvironment (TME) which causes low persistence and functionality of CAR-T cells. In this study, based on the experience of a phase I/II clinical trial (NCT03373097) using a third generation GD2.CAR where sarcoma patients were enrolled, we will explore a new strategy to overcome the limitations observed. Studying the mechanisms responsible for the loss of response, we observed that the ex-vivo T cell manipulation, necessary for gene-modification, induces important metabolic changes in these lymphocytes inducing a deep and lasting blockage of the autophagy pathways which prevents T cells from surviving and invade the tumour. Here, we propose to overcome this block forcing the reactivation of this pathway inducing the expression of one of the autophagy key proteins, Beclin1, on our GD2.CAR-T cells. Based on data published on tumour cells and our preliminary results, the autophagy activation will promote CAR-T cell adaptation inside TME, survival and proliferation even in presence of adverse environment as well as induce a powerful anti-tumour response, mitochondria activity and help to maintain a more immature CAR-T cell phenotype.