Bladder cancer is characterized by a high rate of recurrence following surgical treatments. This phenomenon, not observed in other urogenital malignancies such as renal cancer, is still unexplained. Moreover, there are not markers allowing to predict recurrence in bladder cancer patients after the treatment. We faced these problems hypothesizing that: 1) recurrence in bladder cancer could be related to the existence of sporadic micro-foci of tumor in the residual (after surgery), macroscopically healthy urothelial tissue; 2) the ratio between intratumoral effector and regulatory T cell subsets could represent an efficient biomarker of bladder cancer recurrence. Hence, surgical specimens of both the tumor and the autologous, macroscopically healthy tissue were collected from 24 and 20 patients affected with bladder or renal cancer, respectively. The composition of the intratumoral T cell infiltrate, in terms of effector (IFNγ+ and IL17+ T cells) and regulatory (CD4+CD25hiCD127low and CD8+CD28-CD127lowCD39+ Treg) T cell subpopulations, was analyzed by immunofluorescence, while the gene expression of MAGE-A1 and MAGE-A2 tumor associated antigens was studied by RT-PCR. The T cell infiltrate of bladder and renal cancers were comparable in terms of frequencies of IFNγ+ and IL17+ T cells and CD8+CD28-CD127lowCD39+ Treg, while the CD4+CD25hiCD127low Treg predominated in bladder cancers (P = 0.0006). Importantly, the macroscopically healthy bladder tissue showed a T cell subset composition comparable with that of the autologous tumor, as if a similar immune reaction were at play. Instead, significantly lower frequencies of each of the tested T cell subsets were present in the macroscopically healthy renal tissue than in the autologous tumor. When the molecular gene expression of two tumor associated antigens, MAGE-A1 and MAGE-A2 (frequently expressed by both bladder and renal cancers), was analyzed, similar frequencies of expression were found in both tumors. On the contrary, the macroscopically healthy bladder tissue showed a frequency of MAGE gene expression remarkably higher (and almost comparable to that of the autologous tumor) than the macroscopically renal healthy tissue (P = 0.03) (where MAGE gene expression was almost negligible), supporting for the presence of sporadic micro-foci of tumor in the apparently healthy bladder tissue at the time of surgical intervention.

In order to identify a reliable marker for recurrence, the Teff/Treg intratumoral T cell ratio was analyzed in 13 bladder cancer patients showing (6 patients) or not (7 patients) recurrence after a 2 year follow up. The Teff/Treg intratumoral T cell ratio demonstrated to be a consistent biomarker for recurrence in bladder cancer since a ratio <1 and a ratio >1 were invariably (100% of patients in each group) associated with recurrence and not recurrence, respectively.

These unprecedented findings unveil the possible pathogenic mechanism for recurrence in bladder cancer and suggest that the Teff/Treg intratumoral T cell ratio is a reliable biomarker of recurrence in this disease. If confirmed, they may impact on both prognostic and the therapeutic approaches for bladder cancer.

Citation Format: Daniela Fenoglio, Paolo Traverso, Alessia Parodi, Francesca Kalli, Giuseppina Conteduca, Samuele Tardito, Monica Curto, Francesca Ferrera, Federica Grillo, Luca Mastracci, Francesco Minaglia, Alchiede Simonato, Giorgio Carmignani, Gilberto Filaci. The analyses of immune infiltrate and gene expression of MAGE antigens in bladder cancer allow to explain and predict recurrence. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A020.