Efficacy of chimeric antigen receptor natural killer cells in treatment of ovarian cancer. A meta-analysis of pre-clinical studies.

Chimeric antigen receptor (CAR) therapies have expanded beyond T-cells with addition of natural killer (NK) cells. In ovarian cancer, long-term survival remains poor with the rising need for new therapies. Therefore, this meta-analysis evaluated the pre-clinical efficacy of emerging CAR-NK therapies in ovarian cancer models. Following PRISMA-guidelines and registered protocol (PROSPERO, CRD420251131530), literature from PubMed, Web of Science, and Scopus was retrieved till 30-06-2025 for pre-clinical in-vivo studies of CAR-NK therapy in ovarian cancer. Studies without in-vivo components or human CAR-NK were excluded. Primary outcomes were ratio of means (ROM) for tumor burden and median survival ratio (MSR). Data was analyzed in JASP™ and risk of bias (RoB) was determined using SYRCLE's RoB tool for animal studies. Fourteen experiments (21 CAR-NK groups) were included. CAR-NK significantly reduced tumor burden versus untreated controls (ROM 0.09 [0.03-0.32], p < 0.001) and unmodified/mock NK-cells (ROM 0.18 [0.08-0.42], p < 0.001). Survival was significantly prolonged (MSR 1.67 [1.31-2.14] vs. control; 1.40 [1.08-1.83] vs. unmodified/mock NK, both p < 0.05). Subgroup analyses revealed no significant modifiers, though trends favored mesothelin-targeted and NK-92-based CARs. Limited safety data indicated no cytokine release syndrome or graft-versus-host disease. Small sample size in subgroup analyses and unclear RoB in certain areas are some limitations of this study. However, the pooled estimates were robust to sensitivity analyses and relatively insignificant heterogeneity in survival outcomes could be important for poor long-term survival in ovarian cancers. CAR-NK demonstrates potential pre-clinical efficacy in ovarian cancer models, outperforming naive NK-cells with a consistent survival benefit.