Phase II Study Comparing Disitamab Vedotin Plus Sintilimab and S-1 to Trastuzumab Plus Chemotherapy with or without Sintilimab for First Treatment of HER2-Positive Advanced Gastric or Gastroesophageal Junction Cancer

What this Trial Is About

Researchers are evaluating first-line treatments for adults aged 18 to 75 with HER2-positive advanced gastric or gastroesophageal junction adenocarcinoma that cannot be removed by surgery or has spread to distant sites. This Phase II, randomized, open-label, multicenter trial compares a combination of Disitamab Vedotin, Sintilimab, and S-1 with Trastuzumab plus chemotherapy, with or without Sintilimab, to better understand their effects in this condition. Participants will receive either the experimental combination of Disitamab Vedotin 2.5 mgkg IV every 3 weeks, Sintilimab 200 mg IV every 3 weeks, and S-1 40-60 mg twice daily for 14 days every 3 weeks, or the active comparator treatment of Trastuzumab initial dose 8.0 mgkg, then 6.0 mgkg IV every 3 weeks plus chemotherapy drugs such as Oxaliplatin, Capecitabine, 5-FU, or Cisplatin, with or without Sintilimab. Treatments will continue as per the study schedule to assess their effectiveness and safety. During the trial, participants will be monitored for tumor response at 6 months, progression-free survival, overall survival, duration of relief, and disease control rate up to 12 months after the last participant joins. Safety and adverse events will be observed for up to about 2 years. Regular assessments will include clinical exams and imaging to measure tumor changes and treatment effects. The total duration of participation varies based on treatment and follow-up schedules.

First-line Treatment With RC48 Plus Sintilimab and S-1 in Advanced Gastric Cancer (RCTS2)