A Single-Arm Study of QL1706 Combined With DOS as Neoadjuvant Therapy for Locally Advanced Gastric/GEJ Adenocarcinoma

Inclusion Criteria: 1. Aged 18 to 75 years; male or female. 2. Previously untreated, resectable adenocarcinoma of the stomach or gastroesophageal junction (GEJ). 3. Clinical stage cT3-4a/N+ M0. 4. ECOG performance status 0-1. 5. Adequate organ function within 7 days prior to treatment, meeting the following criteria: (1) Complete blood count (CBC) criteria (without blood transfusion within 14 days): Hemoglobin (Hb) ≥ 90 g/L; Absolute neutrophil count (ANC) ≥ 1.5 × 10⁹/L; Platelet count (PLT) ≥ 80 × 10⁹/L; (2) Serum chemistry criteria: Total bilirubin (TBIL) ≤ 1.5 × upper limit of normal (ULN); Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 2.5 × ULN; Serum creatinine (Cr) ≤ 1.5 × ULN or creatinine clearance (CCr) ≥ 60 mL/min; (3) Doppler echocardiography: left ventricular ejection fraction (LVEF) ≥ lower limit of normal (50%). (4) Thyroid function: thyroid-stimulating hormone (TSH) ≤ upper limit of normal (ULN). 6. Participants of childbearing potential must agree to use effective contraception during the study period and for 6 months after study completion. 7. The participant voluntarily agrees to participate in this study and signs the informed consent form. Exclusion Criteria: 1. Known history of hypersensitivity or allergy to QL1706 or its excipients, tegafur/gimeracil/oteracil (S-1), oxaliplatin, docetaxel, or any of their excipients. 2. History of another malignancy within 5 years prior to screening or concurrent malignancy, except for curatively treated carcinoma in situ of the cervix, non-melanoma skin cancer, and superficial bladder tumors. 3. Patients with distant metastasis and/or unresectable disease; 4. Prior treatment with immune checkpoint inhibitors, including anti-PD-1, anti-PD-L1, and anti-CTLA-4 agents. 5. Receipt of any antineoplastic agents within 4 weeks prior to the first dose of study drug. 6. Patients with gastrointestinal disorders such as intestinal obstruction (including partial obstruction), or those with evidence or risk of gastrointestinal bleeding, perforation, or obstruction. 7. Any bleeding event ≥ CTCAE Grade 3 within 4 weeks prior to enrollment, or unhealed wounds, ulcers, or fractures. 8. Concurrent enrollment in another clinical study, unless it is an observational (non-interventional) study or the follow-up phase of an interventional study. 9. Subjects requiring systemic therapy with corticosteroids (\>10 mg/day prednisone or equivalent) or other immunosuppressive agents within 2 weeks prior to the first dose of study drug. 10. Receipt of live or live-attenuated vaccine within 4 weeks prior to the first dose of study drug. 11. Major surgery or significant trauma within 4 weeks prior to the first dose of study drug. 12. Active or history of autoimmune disease, with the exception of vitiligo or resolved childhood asthma/atopy that requires no intervention in adulthood. 13. History of immunodeficiency, including HIV infection, or other acquired or congenital immunodeficiency disorders, or history of organ transplantation or allogeneic bone marrow transplantation. 14. Subjects with inadequately controlled cardiovascular clinical symptoms or diseases. 15. Severe infection (CTCAE Grade \> 2) within 4 weeks prior to the first dose of study drug. 16. Patients with a history of interstitial lung disease (except for radiation pneumonitis not treated with corticosteroids), non-infectious pneumonitis, or active pulmonary tuberculosis; or a history of active pulmonary tuberculosis within 1 year prior to enrollment, or more than 1 year prior to enrollment if not adequately treated. 17. Pregnant or breastfeeding women. 18. Other concomitant diseases that, in the opinion of the Investigator, pose a serious risk to the subject's safety or may interfere with the subject's ability to complete the study.