A Study of RC48-ADC in Local Advanced or Metastatic Gastric Cancer With the HER2-Overexpression

Inclusion Criteria: * Voluntary agreement to provide written informed consent. * Male or female, Age ≥ 18 years. * Predicted survival ≥ 12 weeks. * Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1. * All female subjects will be considered to be of child-bearing potential unless they are postmenopausal, or have been sterilized surgically.Female subjects of child-bearing potential must agree to use two forms of highly effective contraception. Male subjects and their female partner who are of child-bearing potential must agree to use two forms of highly effective contraception. * Willing to adhere to the study visit schedule and the prohibitions and restrictions specified in this protocol. * Adequate organ function. * All subjects must have inoperable, advanced or metastatic gastric or or gastroesophageal adenocarcinoma * Have had progression or intolerance following receipt of at least two systemic chemotherapy for advanced or metastatic disease. * The HER2 IHC test result is IHC 2+ or IHC 3+, the subject's previous test results (confirmed by the investigator) or the research center's test results are acceptable; the subject can provide the Specimen of primary or metastatic tumor for HER2 review/judgment. * HER2 classic positive (definition: IHC3+ or IHC2+FISH+) and patients who have previously failed standard treatment * According to the RECIST 1.1 standard, there is at least one measurable lesion. Exclusion Criteria: * Known hypersensitivity to …