The goal of this randomized, open-label, phase II clinical trial is to determine whether adding the PD-1/CTLA-4 bispecific antibody QL1706 to standard SOX chemotherapy increases the pathological complete response rate in adults aged 18-75 years with resectable, locally advanced, diffuse-type, HER2-negative gastric adenocarcinoma (cT3-4aNxM0). Participants will be randomly assigned (1:1) to receive 3-4 neoadjuvant cycles of QL1706 plus SOX or SOX alone every 3 weeks, followed by curative-intent gastrectomy with D2 lymphadenectomy, and will be monitored post-operatively every 3 months for 2 years and every 6 months thereafter for recurrence, survival, and safety.
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Parallel
QL1706 (Iparomlimab/Tuvonralimab)
DrugQL1706 is a first-in-class, fixed-ratio bispecific monoclonal antibody produced in a single Chinese hamster ovary cell line that simultaneously targets PD-1 (IgG4 framework) and CTLA-4 (IgG1 framework) with an approximate 2:1 molar ratio. This molecular design delivers dual immune checkpoint blockade in one infusion, distinguishing it from separate-agent combinations such as nivolumab plus ipilimumab. In this study QL1706 is given at 5 mg/kg (actual body weight) as a 60-minute intravenous infusion on day 1 of each 21-day cycle, immediately followed by oxaliplatin 130 mg/m² (2-hour infusion) and oral S-1 (40-60 mg bid days 1-14). The sequence is repeated for 3-4 cycles before planned surgery; no intra-patient dose escalation or reduction is allowed, but infusion may be delayed ≤12 weeks for immune-related adverse events. The comparator arm receives identical SOX chemotherapy without any investigational antibody, ensuring that any difference in pathological outcome can be attributed spec
SOX Chemotherapy
DrugSOX chemotherapy consists of oxaliplatin 130 mg/m² delivered as a 2-hour intravenous infusion on day 1 plus oral S-1 (tegafur 40-60 mg, gimeracil and oteracil potassium in fixed 1:0.4:1 molar ratio) taken twice daily on days 1-14 of a 21-day cycle, repeated for 3-4 cycles before curative-intent gastrectomy. The S-1 dose is calculated by body-surface area: \<1.25 m² → 40 mg, 1.25-1.5 m² → 50 mg, \>1.5 m² → 60 mg per administration.
Pathological complete response (pCR) rate
Pathological complete response (pCR) rate, defined as the proportion of participants who achieve ypT0N0 (absence of viable tumor cells in the resected primary tumor and all examined lymph nodes, Mandard TRG 1 or Becker grade 1) after completion of 3-4 cycles of protocol-specified neoadjuvant therapy and subsequent curative-intent gastrectomy, assessed by central review of H\&E-stained slides according to AJCC 8th edition criteria within 4 weeks of surgery.
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The First Affiliated Hospital with Nanjing Medical University
Lead sponsor
First Affiliated Hospital of Suzhou Medical College
Collaborator
The Affiliated Hospital of Xuzhou Medical University
Collaborator
The Affiliated Jiangning Hospital of Nanjing Medical University
Collaborator
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