Abstract LB-B004: CD8+ Tumor-Infiltrating Lymphocytes and Systemic Immune-Inflammation Index revealed as a Predictor of Response to Neoadjuvant Cadonilimab Plus Chemotherapy in Advanced Ovarian Cancer from the Phase II CANECT Trial

Abstract Background: Results from the CANECT study (NCT05430906) indicate that neoadjuvant cadonilimab (a PD-1/CTLA-4 bispecific antibody) combined with chemotherapy is a promising therapeutic strategy for advanced ovarian cancer (AOC). However, predictive biomarkers to identify potential responders remain limited. This study aimed to further explore biomarkers that predict treatment response and identify the beneficiary population of AOC. Methods: Thirty-seven patients with newly diagnosed AOC from the CANECT trial were analyzed. Pre-treatment tumor samples were assessed for CD8+ tumor-infiltrating lymphocytes (TILs) using immunofluorescence, and dynamic changes in CD8+ TILs were quantified. Peripheral blood samples were collected at baseline and on the first postoperative day to calculate the systemic immune-inflammation index (SII). The SII change rate was defined as the percentage difference between postoperative and baseline values, and the optimal cutoff value was determined by ROC analysis. Progression-free survival (PFS) was analyzed by Kaplan-Meier and log-rank tests, and multivariable Cox regression identified independent prognostic factors. Associations between immune biomarkers and pathological response, R0 resection rate, and PFS were assessed. Results: High baseline CD8+ TILs were significantly associated with improved responses to neoadjuvant Cadonilimab and prolonged PFS (P=0.0216). Cadonilimab induced dynamic changes in CD8+ TILs , decreasing in patients with high baseline levels and increasing in those with low baseline levels, suggesting remodeling of the tumor immune microenvironment. Major pathological response (MPR) was achieved in 8/37 patients (22%) and was strongly linked to immune activation and prolonged PFS (P=0.0308). In parallel, a lower baseline SII was associated with favorable MPR (rs=0.4143, P=0.0184). ROC analysis further demonstrated that baseline SII had a significant predictive value for MPR (AUC=0.7708, P=0.0432). Moreover, patients with decreased SII after treatment exhibited more favorable survival outcomes compared with those showing increased SII (P=0.0434). Notably, high baseline CD8+ TILs combined with low SII predicted the most favorable PFS (P=0.0319). Multivariate analysis identified MPR and R0 resection as independent predictors of prolonged PFS. Conclusions: Neoadjuvant cadonilimab plus chemotherapy reshapes the tumor immune microenvironment and induces meaningful pathological responses in AOC. Baseline CD8+ TILs and dynamic SII changes serve as valuable biomarkers for predicting pathological response and survival, facilitating patient stratification for neoadjuvant immunotherapy. Citation Format: Jie Tang. CD8+ Tumor-Infiltrating Lymphocytes and Systemic Immune-Inflammation Index revealed as a Predictor of Response to Neoadjuvant Cadonilimab Plus Chemotherapy in Advanced Ovarian Cancer from the Phase II CANECT Trial [abstract]. In: Proceedings of the AACR Immuno-Oncology Conference (AACR IO): Discovery and Innovation in Cancer Immunology: Revolutionizing Treatment through Immunotherapy; 2026 Feb 18-21; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Immunol Res 2026;14(2 Suppl):Abstract nr LB-B004.