TIM3 Checkpoint Inhibition Fails to Prolong Survival in Ovarian Cancer-Bearing Mice

Simple Summary Ovarian cancer still ranks as the deadliest gynecological malignancy worldwide. In this research, we aimed to evaluate the potential of anti-TIM3, a relatively novel checkpoint inhibitor, for the treatment of ovarian cancer. Our preclinical studies showed no improvement of survival in ovarian cancer-bearing mice after anti-TIM3 treatment. Additionally, we found no significant immunological changes induced by this therapy in treated mice. However, changing the order of combination treatment with anti-TIM3 and chemotherapy influenced the outcome in mice. Further preclinical studies are required to find and optimize ovarian cancer treatment approaches.Abstract Immune checkpoint inhibitor (ICI) therapy has proven revolutionary in the treatment of some cancers. However, ovarian cancer remains unresponsive to current leading ICIs, such as anti-PD1 or anti-PD-L1. In this article, we explored the potential of an upcoming checkpoint molecule, T-cell immunoglobulin and mucin domain 3 (TIM3), for the treatment of ovarian cancer using a syngeneic orthotopic mouse model (ID8-fLuc). Besides therapeutic efficacy, we focused on exploring immune changes in tumor tissue and peritoneal fluid. Our results showed no improvement in survival in ovarian cancer-bearing mice after anti-TIM3 treatment when used as monotherapy nor when combined with anti-PD1 or standard-of-care chemotherapy (carboplatin/paclitaxel). This was reflected in the unaltered immune infiltration in treated mice compared to control mice. Altering the order of drug administration within the combination treatment altered the survival results, but did not result in a survival benefit over chemotherapy alone. These findings highlight the need for further preclinical studies to find beneficial treatment schemes and combination therapies for ovarian cancer.