Shanghai Henlius Biotech, Inc. announced that, recently, the first patient in has been dosed in mainland China (excluding Hong Kong, Macau and Taiwan regions, the same as below) in a Phase II clinical trial to compare the Company 's HLX22 (anti-human epidermal growth factor receptor-2 (HER2) humanized monoclonal antibody injection) in combination with(trastuzumab injection, EU trade name: Zercepac) ("trastuzumab injection") and chemotherapy (XELOX) against placebo in combination with trastuzumab injection and chemotherapy (XELOX) as first-line therapy for HER2-positive locally advanced or metastatic gastric cancer patients. This two-part study aims to compare the efficacy and safety of HLX22 versus placebo in combination with trastuzumab injection and XELOX, as first-line therapy for HER2-positive locally advanced or metastatic gastric cancer patients. Part one is a safety run-in stage, in which patients will receive 15mg/kg HLX22 in combination with trastuzumab injection and XELOX. Part two is a randomised, double-blind, multi-centre, phase II study. Eligible patients will be randomised 1:1:1 to receive HLX22 (group A: HLX22, 25mg/kg; group B: HLX22, 15mg/kg) in combination with trastuzumab injection and XELOX, or placebo in combination with trastuzumab injection and XELOX (group C). The primary objective of this study is to compare the clinical efficacy in HLX22 and placebo group. The primary endpoints include progression-free survival (PFS) and objective response rate (ORR) assessed by independent radiological review committee (IRRC) per RECIST v1.1. The secondary objectives are to evaluate other efficacy endpoints, safety and tolerability in HLX22 and placebo groups.