To evaluate the clinical efficacy of perioperative treatment with S-1 + oxaliplatin (SOX)+ HLX10 compared with SOX as the control in patients with cT3-4N1-3M0 PD-L1-positive (CPS ≥ 5) locally advanced gastric adenocarcinoma or gastroesophageal junction adenocarcinoma, in a placebo-controlled, double-blind, randomized phase II investigator-initiated clinical study.
Histologically confirmed gastric adenocarcinoma or gastroesophageal junction adenocarcinoma at the study site. (For gastroesophageal junction adenocarcinoma, only patients classified as Siewert type II or type III who do not require surgery involving simultaneous thoracoabdominal incision are eligible.)
Tumor tissue determined to be PD-L1 positive (CPS >= 5) based on pre-screening evaluation by the central laboratory. 3) Diagnosis of cT3-4N1-3M0 disease according to the AJCC/UICC-TNM 8th edition based on assessments performed within 28 days prior to randomization (the same day of the week 4 weeks before the randomization date is acceptable; the same applies hereafter), with no prior systemic treatment. Pre-randomization laparoscopy is not mandatory, but if performed, no non-curative factors (including liver metastasis, peritoneal metastasis, other distant metastases, or positive peritoneal cytology (CY1)) should be observed.
Presence of another active malignancy within 5 years prior to enrollment or concurrently. Patients with cured, localized tumors such as basal cell carcinoma of the skin, squamous cell carcinoma of the skin, superficial bladder cancer, non-invasive prostate cancer, non-invasive cervical cancer, and non-invasive breast cancer are permitted.
Patients scheduled to undergo organ transplantation or bone marrow transplantation.
Myocardial infarction and/or uncontrolled arrhythmia (including QTc interval >= 450 ms in males or >= 470 ms in females) occurring within 6 months prior to randomization (QTc interval calculated using Fridericia's formula).
Cardiac dysfunction classified as NYHA Class III-IV, or left ventricular ejection fraction (LVEF) < 50 percent on echocardiography.