Adebrelimab, Apatinib & SOX for Conversion Therapy in Advanced Gastric/GEJ Cancer

Overview

This is a prospective, single-center, single-arm, open phase II clinical study. Forty-nine participants with pathologically or cytologically confirmed gastric cancer or gastroesophageal junction cancer are scheduled to be enrolled in this study. All participants will be treated with 2 to 8 cycles of adebrelimab, apatinib, oxaliplatin, and tigio before surgery. Participants will evaluate the treatment effect after every 2 cycles of medication. By the investigator assessment as an operable subject, apatinib was discontinued for one cycle. The adjuvant treatment will be determined by the investigators based on the participants' postoperative pathology results. Participants requiring adjuvant therapy, with a postoperative interval of at least 4 weeks, but not more than 10 weeks. When the resection standard isn't met for 8 cycles of treatment, the treatment is switched to a maintenance phase, which the subject treatment regimen is determined by the investigator. During the treatment period, participants will receive the study drugs on Day 1 of each 21-day cycle until evidence of disease progression or unacceptable toxicity.

Study Design: This is a prospective, single-center, single-arm, open-label Phase II clinical study. The study aims to evaluate the efficacy and safety of Adebrelimab combined with Apatinib and SOX regimen as conversion therapy for patients with advanced, unresectable gastric or gastroesophageal junction (GEJ) adenocarcinoma. The study plans to enroll approximately 49 participants who are assessed by investigators as having conversion therapy potential (defined as single organ metastasis, retroperitoneal lymph node metastasis, supraclavicular lymph node metastasis, limited peritoneal metastasis, or invasion of surrounding organs). Treatment Protocol: Eligible participants will receive a four-drug combination therapy consisting of Adebrelimab, Apatinib Mesylate, Oxaliplatin, and S-1. The treatment is administered in 3-week cycles: Adebrelimab: 1200 mg, intravenous infusion on Day 1. Apatinib Mesylate: 250 mg, oral, once daily. Oxaliplatin: 130 mg/m², intravenous infusion on Day 1. S-1 (Tegafur, Gimeracil, and Oteracil Potassium): 40-60 mg (based on Body Surface Area), oral, twice daily on Days 1-14. Study Procedures and Phases: Conversion Treatment Phase: Patients will receive treatment for a minimum of 2 cycles and a maximum of 8 cycles. Resectability will be assessed by the investigator every 2 cycles using imaging evaluation. Surgical Intervention: If the tumor is assessed as resectable: Apatinib will be discontinued for one cycle prior to the planned surgery to ensure safety. Surgery should be performed between 3 to 6 weeks (maximum 6 weeks) after the last dose of the study drug. Post-operative Phase: The decision to administer adjuvant therapy will be made by the investigator based on post-operative pathological results. If adjuvant therapy is required, it will commence at least 4 weeks but no later than 10 weeks after surgery. Maintenance Phase: If the tumor remains unresectable after 8 cycles of combination therapy, the patient will transition to a maintenance phase. The specific treatment regimen during the maintenance phase will be determined by the investigator based on the patient's condition. Follow-up: Upon discontinuation of treatment, patients will undergo safety follow-ups every 30 days until 90 days after the last dose. Subsequently, patients will enter the survival follow-up period to monitor disease recurrence, metastasis, and overall survival. Follow-ups will occur every 3 months for the first 2 years and every 6 months for years 2 to 5.