The immune system plays an active role in the pathogenesis of ovarian cancer 
(OC), as well as in the mechanisms of disease progression and overall survival 
(OS). Immunotherapy in gynecological cancers could help to revert 
immunosuppression and lymphocyte depletion due to prior treatments. Current 
immunotherapies for ovarian cancer, like all cancer immunotherapy, are based on 
either stimulating the immune system or reverting immune suppression. Several 
approaches have been used, including therapeutic vaccines, monoclonal 
antibodies; checkpoint inhibitors and adoptive T cell transfer. Most of these 
therapies are still in early-phase testing (phase I and II) for ovarian cancer, 
but the initial data in ovarian cancer and successful use in other types of 
cancers suggests some of these approaches may ultimately prove useful for 
ovarian cancer as well. Ovarian cancer vaccines have shown only a modest benefit 
in ovarian cancer when used as monotherapy, but these agents may be able to 
enhance antitumor activity when combined with chemotherapy, checkpoint 
inhibitors, or other immunotherapies. Monoclonal antibodies have been explored 
in ovarian cancer but despite encouraging phase II data, randomized studies 
failed to demonstrate significant clinical benefit. Check point inhibitors have 
promising activity in several solid tumors and have demonstrated a favorable 
toxicity profile. Data from early clinical trials utilizing PD1 and PD-L1 
inhibitors showed encouraging results. Ongoing clinical trials are evaluating 
the role of check point inhibitors in combination with chemotherapy. Adoptive T 
cell transfer involves the infusion of ex vivo activated and expanded tumor 
specific T cells, using various sources and types of T cells. While this 
approach has been explored in several hematologic malignancies, it constitutes 
early research in ovarian cancer. Immunotherapy remains investigational in 
ovarian cancer and the benefit of this approach in improving progression-free 
survival (PFS) or OS is unknown. Previous clinical trials have not selected 
patients based on biomarkers and this may explain the negative results. We 
expect to discover that tumor response will relate to the patient's immune 
features and specific tumor characteristics. We are only beginning to realize 
the potential of immunotherapy for ovarian cancer patients, and one goal of 
future clinical trials will be to identify subsets of patient based on 
histologic, molecular, and immune characteristics.