Multiparametric immune profiling to predict the risk of cancer development in chronic immune suppressed solid organ transplant patients

Solid organ transplantation (SOT) is currently recognized as the treatment of choice of patients with end-stage disease, but the length and type of pharmacologic immunosuppression strongly affect patients’ immune system resulting in enhanced immune evasion strategies, oncogenic virus reactivation and malignant transformation. On these grounds, a more in depth characterization of functional defects of immune cells related to the different immunosuppressive regimens and the occurrence of relevant clinical events might be relevant to design novel and integrated cancer surveillance practices for immune suppressed transplant recipients. The main purpose of this study is to identify a reliable immunologic profile predictive of cancer development and progression in SOT patients through a multiparametric phenotypic and functional characterization of dendritic cells (DCs) and T lymphocytes in SOT patients treated with different immunosuppressive regimens. In particular, the activation status of these cells was assessed in serial samples through Multispectral imaging flow cytometry, whereas the extent of T-cell responses specific for pathogenic viruses and tumor-associated antigens was measured by ELIspot IFN-γ assay. Data obtained in SOT patients who developed a tumor (n=15) were compared with those from patients tumor-free during the follow-up (n=58). Interestingly, we observed that patients experiencing cancer onset during surveillance had lower numbers of activated CD4+ and CD8+ T lymphocytes and a decreased activation of monocyte-derived DCs as compared with the “no tumor” cohort and healthy donors. Moreover, we found that tumor onset patients display higher spontaneous T-cells responses against the “universal” tumor associated-antigens hTERT and Survivin if compared to “no tumor” patients and healthy controls. Globally, patients of the “tumor” cohort showed significantly higher levels of circulating hTERT mRNA as compared to those of the “no tumor” cohort, even before the diagnosis of cancer, suggesting that this biomarker could usefully complement the immunomonitoring of SOT patients and help identify those at risk of cancer. We also found that the levels of HPV-specific T-cell responses observed in both patient cohorts were significantly lower both at baseline and at follow up as compared to those of healthy donors, whereas no difference was detected with regard to T-cell responses specific for CMV and EBV. Given the critical role of severe immunosuppression that characterizes transplanted patients and the importance of immune surveillance integrity in the prevention and control of malignancies, the results of the present study provide a strong rationale to design and activate a prospective study in a larger cohort of SOT patients aimed at validating the role of the immune biomarkers identified as potential predictors of the risk of cancer in the highly heterogeneous setting of SOT patients.