Epithelial ovarian cancer (EOC) usually spreads into the peritoneal cavity, thereby providing an opportunity for intraperitoneal adoptive immunotherapy with Vc9Vd2 T lymphocytes, a T cell subpopulation endowed with high lytic properties against tumor cells. However, previous studies have reported that Vc9Vd2 T cells fail to expand from peripheral blood mononuclear cells in one-third of patients with cancer. Here, from a cohort of 37 patients with EOC, a multiple correspondence analysis identified three populations, one of which was not suitable for Vc9Vd2 T-cell adoptive therapy. Interestingly, the ineligible patients were identified based on the frequency of Vc9Vd2 T cells in their peripheral blood and the patients' age. The average time to tumor recurrence was also found to be significantly different between the three populations, suggesting that the innate immune response is involved in EOC prognosis. A dramatic decrease in the lytic properties of Vc9Vd2 T cells occurred following incubation with ascitic supernatant and was found to be associated with reduced perforin/granzyme degranulation. Prostaglandin E2, but not IL-6, IL-10, VEGF or TGF-b, showed immunosuppressive effects in Vc9Vd2 T cells. Interestingly, our results emphasize that pretreating ovarian tumor cells with zoledronate partially reverses the immunosuppressive effects of ovarian cancer-associated ascites and restores a high level of lytic activity. These data sustain that optimal Vc9Vd2 T-cell adoptive immunotherapy previously requires counteracting the tumor immunosuppressive microenvironment. Altogether, our findings provide a rationale for clinically evaluating Vc9Vd2 T-cell adoptive immunotherapy with intraperitoneal carcinomatosis presensitization by zoledronate in patients with EOC.Epithelial ovarian cancer (EOC) is the fifth most frequent cancer among women and the fourth most common cause of cancer-related deaths among women.1 More than 70% of patients are diagnosed when the cancer has spread beyond the ovaries, and these patients have low median survival rates.2 The prognosis is poor, with a 5-year survival rate of only 30%, and the rate is less than 10% for patients with bulky residual disease remaining after surgery and chemotherapy, which emphasizes the need for innovative treatments.3 The inflammatory microenvironment of ovarian carcinomas prevents the maturation of myeloid cells, favors regulatory T-cell development and restrains the cytotoxic activity of effector T lymphocytes, leading to the escape of the tumor from the immune system. 4 Thus, research is ongoing to develop innovative approaches aimed at stimulating the immune system. 5 The preferential spread pattern of EOC in the peritoneal cavity offers an excellent opportunity for the regional administration of adoptive T-cell therapy.2 Some pilot trials have shown the feasibility of and promising