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Abstract The hostile tumor microenvironment in ovarian cancer is an active deterrent to the efficacy of immunotherapeutic agents such as immune checkpoint inhibitors, Chimeric Antigen Receptor (CAR) T-cells, and Bispecific T-cell Engagers (BiTEs). Tumor-associated macrophages (TAMs) and Myeloid-Derived Suppressor Cells (MDSCs) have been shown to promote an immunosuppressive metabolic and cytokine tumor microenvironment that is detrimental to cytotoxic effector T-cell activity in ovarian cancer. These immunosuppressive cells are also associated with poor prognostic outcomes. The ideal approach to modulating TAMs and MDSCs is unknown. Data from preclinical models support reprogramming these cells to a more inflammatory phenotype or removing them from the tumor microenvironment entirely. However, neither approach has translated to clinical benefits. We have previously demonstrated that CAR-T cells modified to secrete IL-18 exerted their therapeutic effects partly via polarization of bone marrow macrophages towards an M1 phenotype. We also found that the depletion of TAMs improved CAR-T cell efficiency, even when these CAR-T cells were co-modified to secrete IL-12. Because of the propensity for monocytes to be recruited to the ovarian cancer tumor microenvironment, we evaluated the efficacy of monocytes genetically modified to secrete BiTEs. First, we designed and evaluated BiTEs that recognize the retained portion of MUC16 (Muc16-ecto) and CD3+ T-cells and showed that these BiTEs were efficacious in vitro and in vivo in a xenograft model of ovarian cancer. We validated that monocytes transduced to secrete Muc16-specific BiTEs (Mono-BiTEs) could effectively lyse tumor cells in vitro and suppress xenograft ovarian cancer cells in vivo. Adding IFN-alpha and IFN-gamma to Mono-BiTEs significantly improved Mono-BiTEs antitumor efficacy over BiTE therapy or unmodified monocyte therapy alone. Adoptive cell therapy with genetically engineered autologous monocytes could provide an alternative approach to reprograming or eliminating myeloid-derived cells in ovarian cancer. Citation Format: Oladapo Yeku. Friend or foe: Reevaluating the therapeutic potential of monocytes and tumor-associated macrophages in ovarian cancer abstract. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84 (5 Suppl₂): Abstract nr IA006.
Oladapo Yeku (Mon,) studied this question.