Clinical study on the assessment of first-line drug efficacy in advanced gastric cancer by monitoring circulating tumor cells through a self-developed microfluidic chip.

e15041 Background: Most gastric cancer patients are in advanced stages with poor prognosis and high mortality. How to improve the diagnosis rate, simply and accurately evaluate treatment efficiency and predict post-treatment Tumor recurrence and metastasis, there is still a lack of an ideal detection method. This study focuses on the application of circulating tumor cells in predicting the first-line efficacy of gastric cancer. Methods: This study is designed as a prospective, single-center, exploratory clinical application study. The correlation between changes in the number and classification of CTCs and drug efficacy was analyzed. Brief description of CTC criteria: Epithelial type，Mesenchymal type，Epithelial- mesenchymal type. Results: This study enrolled a total of 98 first-line treatment patients with advanced gastric cancer who met the inclusion and exclusion criteria. They were followed up until September 8, 2024. The dynamic changes in mesenchymal CTCs, epithelial- mesenchymal CTCs, and total CTCs before and after two cycles of treatment are related to the ORR and DCR. After 2 cycles of treatment, there is a positive correlation between mesenchymal CTCs, epithelial- mesenchymal CTCs, the total number of CTCs and peritoneal metastasis. Early changes in mesenchymal CTCs and epithelial- mesenchymal CTCs after treatment are more sensitive in patients with peritoneal metastasis, which is helpful for evaluating and predicting the efficacy of gastric cancer peritoneal metastasis. Combining different cut-off values, the changes in different subtypes of CTCs after 2 cycles of treatment showed higher sensitivity in predicting PFS and OS, and the changes in mesenchymal CTCs, epithelial- mesenchymal CTCs, and total CTCs before and after treatment could predict prognosis. Compared with patients who showed an increase in expression and total CTCs before and after two cycles of treatment, patients with mesenchymal and epithelial- mesenchymal CTCs had shorter PFS and OS than those who showed a decrease or no change, and the difference was statistically significant (all p < 0.01). After 2 cycles of treatment, an increase in the total number of CTCs, as well as the number of mesenchymal and epithelial- mesenchymal CTCs, indicates poor treatment efficacy. Conclusions: The results of this study suggest that CTCs testing may be used as an auxiliary efficacy assessment method in addition to standard imaging testing methods. Changes in CTC, especially mesenchymal type, epithelial- mesenchymal type, and total number of CTCs, are related to PFS and OS of first-line gastric cancer. Early detection of CTCs levels during the treatment of patients with advanced gastric cancer may be able to dynamically evaluate the treatment effect in real time, especially for patients with peritoneal metastasis of gastric cancer. Clinical trial information: ChiCTR2000036946 .