TLR9 and ovarian carcinoma: Therefore, to investigate the contribution of the innate immune system to the effect of combinatorial immunotherapeutic treatments based on TLR9 stimulation and PD-1 blockade, we utilized athymic nude mice, in which the effector functions of innate immune cells can clearly emerge without any interference from T lymphocytes, xenografted with IGROV-1 human ovarian cancer cells.