Predicting Efficacy of Preoperative Immunotherapy in Advanced Gastric Cancer

This prospective study intends to employ FAPI and Grazytracer PET/CT to predict the therapeutic response to preoperative immunotherapy-based combination regimens (neoadjuvant therapy or conversion therapy) in patients with advanced gastric cancer. Enrolled patients will undergo paired FAPI PET/CT and Grazytracer PET/CT examinations at baseline and at a predefined follow-up time point (either after one cycle or at treatment completion). With the tumor regression grade (TRG) serving as the reference standard, the study will investigate the correlation between PET/CT-derived parameters and therapeutic response, as well as the predictive performance of these parameters for prognosis. This study is expected to provide an early, non-invasive predictive tool for preoperative immunotherapy-based combination therapy in advanced gastric cancer, thereby avoiding ineffective treatment and the associated healthcare costs and patient burden; moreover, it is anticipated to offer molecular imaging-based evidence for treatment stratification in gastric cancer immunotherapy, ultimately facilitating the optimization of precision therapeutic strategies.

Inclusion criteria

• Age: 18 years ≤ age ≤ 80 years.
• The subject must have histopathologically confirmed gastric adenocarcinoma via gastroscopic biopsy.
• Clinical stage: cT3-4aN0-3M0 (according to the 8th edition UICC gastric cancer cTNM) with surgically resectable locally advanced gastric cancer, or cT3-4bN1-3M1 (non-peritoneal metastasis) with advanced gastric cancer.
• Eastern Cooperative Oncology Group (ECOG) performance status score: 0-1.
• Hematology: white blood cell count > 4 × 10⁹/L, neutrophil count > 2 × 10⁹/L, hemoglobin > 90 g/L, and platelet count > 100 × 10⁹/L.
• Cardiac function: left ventricular ejection fraction (LVEF) > 50%.
• Liver function: total bilirubin < 1.5 × the upper limit of normal (ULN); aspartate aminotransferase (AST) and alanine aminotransferase (ALT) < 1.5 × ULN.
• Renal function: serum creatinine ≤ 1.5 × ULN, or estimated glomerular filtration rate (eGFR) > 60 mL/min.
• The subject must agree to participate in this clinical trial and sign the informed consent form.
• The subject must demonstrate good compliance, commit to adhering to the study procedures, and cooperate with the full implementation of the study process.
• The subject must have no plans for pregnancy within 6 months.

Exclusion criteria

• Patients with other primary malignancies within 5 years, with the exception of adequately treated basal cell carcinoma and squamous cell carcinoma of the skin.
• Patients with known hypersensitivity or contraindications to chemotherapeutic or immunotherapeutic agents.
• Patients with severe concomitant diseases that, in the investigator's judgment, render the patient unsuitable for enrollment in this clinical study, including but not limited to severe cardiopulmonary insufficiency, severe bone marrow suppression, and severe hepatic or renal dysfunction.
• Patients with severe psychiatric disorders, or those who are mentally impaired and unable to cooperate with the required study assessments.
• Women who are pregnant, possibly pregnant, or breastfeeding.
• Patients with poor compliance.