Gastric and Gastroesophageal Junction (GEJ) Adenocarcinoma

This study investigates treatment of cadonilimab or placebo combined with SOX chemotherapy (oxaliplatin + tegafur-gimeracil-oteracil potassium) given before surgery (neoadjuvant) and cadonilimab or placebo combined with SOX chemotherapy after surgery (adjuvant), will work and be safe for the treatment of resectable (removable by surgery) gastric or gastroesophageal cancer.

The purpose of this observational study is to collect clinical information, blood, and tumor tissue samples from participants diagnosed with stage I, stage II, or operable stage III cancer in select solid tumors. The information collected will be used to develop tests to better understand cancer, for example, to improve cancer detection and to assess the risk of cancer coming back. Participants will receive routine standard of care from their doctor and their involvement is expected to last for approximately five and a half (5.5) years.

The study is being conducted to evaluate the efficacy, safety and tolerability of radiotherapy and chemotherapy, apatinib with camrelizumab in the neoadjuvant (prior to surgery) and adjuvant (after surgery) treatment of previously untreated adults with gastric and gastroesophageal junction (GEJ) adenocarcinoma.