Circulating tumor cells as prognostic biomarkers in advanced gastric cancer treated with CDC25B phosphatase inhibitors.

e16050 Background: Targeted therapies, such as the CDC25B inhibitor menadione, have shown promise in treating gastric cancer (GC). Circulating tumor cells (CTCs) are emerging as a tool for monitoring treatment efficacy. This study aims to assess the impact of CTC counts on treatment outcomes and the efficacy of menadione in GC. Methods: This analysis of a phase II randomized trial included patients with gastric adenocarcinoma treated with Menadione + XELOX or XELOX alone. Kaplan-Meier curves were used to analyze overall survival (OS) and progression-free survival (PFS), comparing CTC responders (CTC resp) and non-responders (No CTC resp). Hazard ratios (HR) and 95% confidence intervals (CI) were calculated, and p-values < 0.05 were considered significant. Results: Of the 107 patients, 54 received Menadione + XELOX and 53 received XELOX alone. In the Menadione group, CTC responders had better OS, with HRs of 2.04 at 3 months, 1.83 at 6 months, and 25.69 at 15 months (p < 0.001). PFS analysis showed a higher risk of progression in No CTC responders, with HRs of 2.04 at 3 months and 14.63 at 15 months (p < 0.001). Conclusions: Patients without CTC response had worse OS and PFS in both treatment groups, suggesting that CTC response could be a valuable predictor of clinical outcomes, warranting more intensive monitoring and tailored therapies for specific subgroups. Clinical trial information: RBR-76j763k .