Using ctDNA to Guide Treatment Decisions for Stage III Gastric Cancer

Circulating Tumor DNA Monitoring for Postoperative Adjuvant Therapy Decision-Making in Stage III Gastric Cancer: A Prospective, Multicenter, Randomized Controlled Phase III Clinical Trial

The goal of this randomized, controlled phase III clinical trial is to evaluate whether combining Tislelizumab with standard SOX chemotherapy improves disease-free survival (DFS) compared to chemotherapy alone in patients with stage III gastric or gastroesophageal junction adenocarcinoma who are ctDNA-MRD positive after surgery. The study will enroll 416 patients across multiple centers and will compare outcomes between two groups: patients receiving tislelizumab plus SOX chemotherapy and those receiving standard SOX chemotherapy alone. The primary questions to be addressed are whether the combination therapy improves 1-year DFS rates and whether it demonstrates an acceptable safety profile. Participants will provide tissue and blood samples for ctDNA-MRD testing, undergo postoperative adjuvant therapy (chemotherapy ± immunotherapy), and complete regular follow-up visits to monitor treatment response and safety. The trial will assess key outcomes, including DFS, overall survival (OS), and ctDNA clearance rates, to determine the clinical benefit and safety of tislelizumab in this population.

Study Overview

• Status: Active, not recruiting
• Conditions: Gastric Cancer Stage III
• Intervention / Treatment: Drug: Tislelizumab + SOX Chemotherapy; Drug: SOX Chemotherapy

• Study Type: Interventional
• Enrollment (Estimated): 416
• Phase: Phase 3

Contacts and Locations

Study Locations

• China
  • Jiangsu
    • Nanjing, Jiangsu, China, 210029
      • First Affiliated Hospital with Nanjing Medical Unviersity

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

Histological or Cytological Confirmation: Patients must have a confirmed diagnosis of stage III gastric or gastroesophageal junction adenocarcinoma (according to the 8th edition of the American Joint Committee on Cancer (AJCC) staging system) based on histological or cytological examination.

Surgical Resection: Patients must have undergone D2 or more extensive lymph node dissection surgery, with available tumor tissue samples. Patients who received neoadjuvant therapy prior to surgery are excluded.

Age: Patients must be between 18 and 75 years of age. General Condition: Patients must have an Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.

Informed Consent: Patients must be able to understand the study protocol and voluntarily participate in the study, providing written informed consent.

Compliance: Patients must demonstrate good compliance, willingness to adhere to the treatment regimen specified in the study protocol, and ability to provide blood samples at designated time points.

Clinical Data: Patients must have complete imaging and pathological clinical data available.

Life Expectancy: Patients must have an expected survival of more than 3 months. Organ and Marrow Function: Patients must have adequate organ and bone marrow function.

Exclusion Criteria:

Inability to Confirm Diagnosis: Patients who cannot be confirmed as having primary stage III gastric or gastroesophageal junction adenocarcinoma through histological or cytological examination.

Inability to Receive Treatment: Patients who are unable to receive immune checkpoint inhibitors or SOX chemotherapy.

Inability to Comply with Follow-up: Patients who are unable to adhere to the predetermined clinical follow-up schedule.

Inability to Accept Study Protocol: Patients who cannot accept the treatment regimen specified in the study protocol.

Inability to Provide Efficacy Assessment: Patients who cannot undergo or provide designated efficacy assessment methods such as CT scans.

Autoimmune Diseases: Patients with a history of autoimmune diseases. Psychiatric or Substance Abuse Issues: Patients with a history of substance abuse that cannot be discontinued or those with psychiatric disorders, or any severe and/or uncontrolled medical conditions.

Severe Comorbidities: Patients with any severe comorbidities that, in the investigator's judgment, may jeopardize patient safety or completion of the study.

Pregnancy or Breastfeeding: Pregnant or breastfeeding women. Prior Neoadjuvant Therapy: Patients who received neoadjuvant therapy prior to surgery or intraoperative chemotherapy infusion.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Tislelizumab + SOX Chemotherapy; Patients in this group will receive tislelizumab (200 mg IV every 3 weeks for 1 year) in combination with SOX chemotherapy (oxaliplatin 130 mg/m² IV every 3 weeks and tegafur based on body surface area orally twice daily for 14 days every 3 weeks).	Drug: Tislelizumab + SOX Chemotherapy; The intervention in this study involves the use of tislelizumab, a humanized IgG4 anti-PD-1 monoclonal antibody, in combination with the standard SOX chemotherapy regimen for postoperative adjuvant therapy in patients with stage III gastric or gastroesophageal junction adenocarcinoma who are ctDNA-MRD positive. Tislelizumab is administered at a dose of 200 mg intravenously every 3 weeks for a total duration of 1 year, alongside 6-8 cycles of SOX chemotherapy. The SOX regimen includes oxaliplatin (130 mg/m² intravenously every 3 weeks) and tegafur, with the dose of tegafur determined based on body surface area and administered orally twice daily for 14 days every 3 weeks.
Active Comparator: SOX Chemotherapy Alone; Patients in this group will receive standard SOX chemotherapy alone (oxaliplatin 130 mg/m² IV every 3 weeks and tegafur based on body surface area orally twice daily for 14 days every 3 weeks).	Drug: SOX Chemotherapy; The control group will receive standard SOX chemotherapy alone, serving as an active comparator to evaluate the incremental benefit of adding tislelizumab. This design ensures a rigorous comparison while maintaining alignment with current standard-of-care practices.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
disease-free survival (DFS)	1 year

Secondary Outcome Measures

Outcome Measure	Time Frame
overall survival(OS)	3 years

Collaborators and Investigators

• Sponsor: The First Affiliated Hospital with Nanjing Medical University
• Collaborators: The Affiliated Hospital of Xuzhou Medical University; First Affiliated Hospital of Suzhou Medical College; Nanjing Gaochun People's Hospital; The Affiliated Jiangning Hospital of Nanjing Medical University

Study record dates

Study Major Dates

• Study Start (Actual): December 1, 2024
• Primary Completion (Estimated): December 31, 2026
• Study Completion (Estimated): December 31, 2029

Study Registration Dates

• First Submitted: April 15, 2025
• First Submitted That Met QC Criteria: April 15, 2025
• First Posted (Actual): April 22, 2025

Study Record Updates

• Last Update Posted (Estimated): July 1, 2025
• Last Update Submitted That Met QC Criteria: June 26, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Gastrointestinal Neoplasms; Digestive System Neoplasms; Digestive System Diseases; Gastrointestinal Diseases; Stomach Diseases; Stomach Neoplasms; Antineoplastic Agents, Immunological; Antineoplastic Agents; Tislelizumab
• Other Study ID Numbers: CLAYMORE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No