V delta 2 T cells are associated with favorable clinical outcomes in patients with bladder cancer and their tumor reactivity can be boosted by BCG and zoledronate treatments

Background Bladder cancer is an important public health concern due to its prevalence, high risk of recurrence and associated cost of management. Although BCG instillation for urothelial cancer treatment is the gold-standard treatment for this indication, repeated BCG treatments are associated with significant toxicity and failure, underlining the necessity for alternative or complementary immunotherapy and overall for better understanding of T-cell responses generated within bladder mucosa. Tumor-infiltrating lymphocytes (TIL) have long been recognized as a crucial component of the tumor microenvironment for the control of tumor. Among TIL, unconventional gamma delta T cells sparked interest due to their potent antitumor functions. Although preclinical mouse xenograft models demonstrated the relevance of using gamma delta T cells as a novel therapy for bladder cancer (BCa), the contribution of gamma delta T cells in BCa patients' pathology remains unaddressed. Methods Therefore, we first determined the proportion of intratumor gamma delta T cells in muscle-invasive patients with BCa by deconvoluting data from The Cancer Genome Atlas (TCGA) and the frequency of blood V delta 1, V delta 2, and total gamma delta T cells, by flow cytometry, from 80 patients with BCa (40 non-muscle and 40 muscle-invasive patients with BCa), as well as from 20 age-matched non-tumor patients. Then we investigated in vitro which treatment may promote BCa tumor cell recognition by gamma delta T cells. Results We observed a decrease of gamma delta T-cell abundance in the tumor compared with corresponding normal adjacent tissue, suggesting that the tumor microenvironment may alter gamma delta T cells. Yet, high intratumor gamma delta T-cell proportions were significantly associated with better patient survival outcomes, potentially due to V delta 2 T cells. In the blood of patients with BCa, we observed a lower frequency of total gamma delta, V delta 1, and V delta 2 T cells compared with non-tumor patients, similarly to the TCGA analysis. In addition, a favorable clinical outcome is associated with a high frequency of circulating gamma delta T cells, which might be mainly attributed to the V delta 2 T-cell subset. Furthermore, in vitro assays revealed that either BCG, Zoledronate, or anti-BTN3 agonistic antibody treatment of bladder tumor cells induced V delta 2 T-cell cytolytic (CD107a(+)) and cytokine-production (IFN-gamma and TNF-alpha). Strikingly, combining BCG and Zoledronate treatments significantly elicited the most quantitative and qualitative response by increasing the frequency and the polyfunctionality of bladder tumor-reactive V delta 2 T cells. Conclusions Overall, our results suggest that (1) V delta 2 T cells might play a prominent role in bladder tumor control and (2) non-muscle invasive patients with BCa undergoing BCG therapy may benefit from Zoledronate administration by boosting V delta 2 T cells' antitumor activity.