A Phase Ⅲ Clinical Study of HLX22 in Combination With Trastuzumab and Chemotherapy for the Treatment of Gastroesophageal Junction and Gastric Cancer

Inclusion Criteria

• Male/female who are at least 18 years of age on the day of signing the informed consent.
• With histologically or cytologically confirmed diagnosis of previously untreated, locally advanced unresectable or metastatic HER2-positive gastric or gastroesophageal junction adenocarcinoma.
• Had measurable disease as assessed by IRRC according to the RECIST v1.1, the target lesion must not be a bone metastatic lesion only.
• HER2-positive tumor defined as either IHC 3+ or IHC 2+ in combination with ISH+ or FISH, as assessed by a central laboratory on a primary or metastatic tumor.
• ECOG PS within 7 days before randomization: 0-1.
• Expected survival ≥ 6 months.
• Had adequate organ function

Exclusion Criteria

• Patients with other malignant tumors within 2 years before the randomization.
• Evidence of disease progression within 6 months (before randomization) after completion of prior neoadjuvant or adjuvant chemotherapy (or both) or radiotherapy for gastric adenocarcinoma or gastroesophageal junction adenocarcinoma.
• Previous treatment with any HER2-target therapy.
• Active gastrointestinal bleeding
• Presence of central nervous system (CNS) metastases.
• Left ventricular ejection fraction (LVEF) < 55%.
• Subjects who had known history of severe allergy to any monoclonal antibody or any component of study treatment.