The overall efficacy of neoadjuvant treatment for advanced gastric cancer is limited due to significant heterogeneity in patient responses. While neoadjuvant therapy offers hope for improved clinical outcomes, the key challenge is accurately predicting individual treatment responses. Identifying reliable biomarkers to guide treatment decisions is therefore critical. Immune factors are pivotal in the efficacy of gastric cancer treatment, but most research has predominantly focused on the tumor immune microenvironment. This study aims to validate the predictive value of systemic immune markers in predicting neoadjuvant treatment responses in advanced gastric cancer.

Building on our previous research, where we established a retrospective cohort of patients with advanced gastric cancer undergoing preoperative chemotherapy, we employed a novel serum proteomics platform based on proximity extension assays (PEA) to measure key immune protein levels in patient serum. This led to the development of the PSRscore system, a serum immune protein score that effectively predicted tumor regression after preoperative chemotherapy (published in Cell Reports Medicine, doi: 10.1016/j.xcrm.2023.100931).

In this prospective cohort study, we will enroll 166 patients with resectable advanced gastric cancer undergoing neoadjuvant chemotherapy. Baseline serum samples will be collected prior to treatment, and the PSRscore will be used to predict tumor regression. Pathological evaluation post-chemotherapy will confirm tumor response, helping to further validate and refine the PSRscore system. Additionally, an exploratory cohort of 40 patients receiving combined neoadjuvant chemotherapy and immunotherapy will be included to evaluate the correlation between PSRscore and clinical benefit from immunotherapy.

This research is expected to lead to the development of a predictive diagnostic kit based on the PSRscore for advanced gastric cancer patients undergoing neoadjuvant therapy, with the ultimate goal of improving clinical decision-making and enhancing treatment outcomes for gastric cancer patients.

Inclusion Criteria

1. Males or females aged 18 to 75 years;
2. Newly diagnosed histologically confirmed gastric adenocarcinoma;
3. Lesion located in the stomach or gastroesophageal junction as assessed by endoscopic ultrasound and enhanced CT, with clinical staging of T3-4NxM0 (based on the 8th edition of AJCC TNM classification);
4. Determined suitable for neoadjuvant chemotherapy or neoadjuvant chemotherapy combined with immunotherapy after multidisciplinary consultation, with potential for curative resection post-treatment. The chemotherapy regimen is restricted to fluoropyrimidine and platinum-based systemic chemotherapy; the immunotherapy regimen is restricted to immune checkpoint inhibitors.

Exclusion Criteria

1. Prior receipt of any anti-tumor therapy for current gastric cancer or receipt of anti-tumor drugs for other conditions within the past 4 weeks;
2. Presence of another malignancy or multiple primary tumors;
3. Serious comorbidities with a life expectancy of less than 5 years;
4. Severe chronic or active infections requiring systemic anti-infective therapy;
5. Blood transfusion within the past week;
6. Receipt of corticosteroid or immunosuppressive therapy within the past 2 weeks;
7. Administration of a live vaccine within the past 4 weeks.

Resectable gastric cancer patients who received neoadjuvant treatment followed by gastrectomy with D2 lymphadenectomy at Zhongshan Hospital, Fudan University