QL1706-SOX vs SOX Alone as Neoadjuvant Therapy for Resectable Diffuse-Type Gastric Cancer

Inclusion Criteria: Histologically confirmed diffuse-type gastric adenocarcinoma (Lauren classification) with signet-ring cells ≥ 50 % of tumor volume HER2-negative by IHC or ISH per ASCO/CAP guidelines Clinical stage cT3-4aNxM0 (AJCC 8th ed.) on baseline EUS + contrast-enhanced CT/MRI; disease judged resectable by multidisciplinary team No prior gastric surgery, chemotherapy, radiotherapy, or immunotherapy for cancer Age 18-75 years; ECOG performance status 0-1 Adequate organ function (ANC ≥ 1.5 × 10⁹/L, platelet ≥ 100 × 10⁹/L, Hb ≥ 9 g/dL, ALT/AST ≤ 2.5 × ULN, TBIL ≤ 1.5 × ULN, creatinine ≤ 1.5 × ULN and calculated CrCl ≥ 60 mL/min, INR/PT ≤ 1.5 × ULN) within 14 days before randomization Left-ventricular ejection fraction ≥ 50 % by echocardiography; no clinically significant ECG abnormalities Negative serum β-hCG pregnancy test ≤ 7 days of first dose for women of child-bearing potential; agreement to use effective contraception through 6 months post-surgery Life expectancy ≥ 6 months Signed informed consent; able to comply with study procedures and follow-up Exclusion Criteria: Mixed or intestinal Lauren histology; mucinous or hepatoid variants Active gastrointestinal bleeding or endoscopic evidence of major vessel invasion Other malignancy within 5 years (except curatively treated basal-cell carcinoma, cervical carcinoma in situ, or superficial bladder cancer) Prior exposure to any anti-PD-1, anti-PD-L1, anti-CTLA-4, or other T-cell co-stimulatory/antagonist agents Auto…