A Study to Evaluate the Efficacy and Safety of MRG003 in Patients With Advanced Gastric Cancer.

The objective of this study is to assess the safety, efficacy, pharmacokinetics, and immunogenicity of MRG003 in patients with EGFR-positive, HER2-negative, inoperable locally advanced or metastatic gastric cancer.

Approximately 6054 patients will be enrolled to evaluate the safety and preliminarily efficacy of MRG003. Patients will receive 2.0 mg/kg dose of MRG003 intravenously every 3 weeks (Q3W) and may receive up to 24 months of MRG003 if there is evidence of clinical benefit to the patients.

Eligibility Criteria:
Inclusion Criteria:

* - Willing to sign the ICF and follow the requirements specified in the protocol.
* Age: 18-75 years (including 18 and 75), both genders.
* Expected survival time≥3 months.
* Patients with histologically confirmed inoperable locally advanced or metastatic gastric adenocarcinoma.
* Tumor tissue must be EGFR positive and HER2 negative.
* Patients must have measurable lesions according to the Response Evaluation Criteria in Solid Tumors (RECIST v1.1).
* ECOG performance score 0 or 1.
* Organ functions and coagulation function must meet the basic requirements.
* No severe cardiac dysfunction with left ventricular ejection fraction (LVEF) ≥ 50%.
* Serum or urine pregnancy test negative within 7 days before the first dose of investigational drug.
* Patients with childbearing potential must use effective contraception during the treatment and for 6 months after the last dose of treatment.

Exclusion Criteria:

* - Squamous cell carcinoma, carcinoid, neuroendocrine carcinoma, undifferentiated carcinoma, or other gastric cancers,or adenocarcinoma with other pathological components that cannot be classified, or adenocarcin oma accompanied by other pathological components.
* History of hypersensitivity to any component of the study drug or to other EGFR-targeting agents.
* Antitumor biological therapy or immunotherapy, targeted small molecule therapy and have history of systemic chemotherapy within 4 weeks before the first administration of the investigational drug, or major surgery. Traditional Chinese medicine, Chinese patent medicine or traditional Chinese medicine formula with anti-tumor effect should not be used within 2 weeks before the first administration.
* Potent CYP3A4 inhibitors or inducers are in use and cannot be discontinued.
* Known active CNS metastasis.
* Uncontrolled pleural effusion, pericardial effusion or recurrent ascites.
* Patients with intestinal obstruction requiring treatment were excluded.
* Residual toxicity reactions caused by previous anti-tumor treatment or abnormal values of laboratory tests higher than grade 1 (CTCAE v5.0).

Peripheral neuropathy ≥ Grade 2 (NCICTCAE version 5.0).

* Uncontrolled or poorly controlled hypertension.
* Uncontrolled or poorly controlled heart disease.
* Known active hepatitis B or C.
* Active bacterial, viral, fungal, rickettsia, or parasitic infections that require systemic anti-infective treatment.
* Known history of malignancy.
* History of ophthalmologic abnormalities
* History of severe skin disease
* Moderate to severe dyspnea at rest caused by advanced cancer or its complications, or severe primary lung disease, oxygen saturation \< 93% in non-oxygen state, or history of any interstitial lung disease or interstitial lung disease (ILD) requiring oral or intravenous glucocorticoids or non-infectious pneumonia.
* Patients with a history of active bleeding, coagulopathy, or receiving coumarin anticoagulation therapy.
* History of pulmonary embolism or deep vein thrombosis within 6 months before the first administration of the investigational drug.
* Patients with a history of active bleeding, coagulopathy, or receiving coumarin anticoagulation therapy.

Decompensated cirrhosis of Child-Pugh class B, C

* Complicated with severe, uncontrolled infection or known human immunodeficiency virus (HIV) infection, or diagnosed as acquired immunodeficiency syndrome (AIDS); or uncontrolled autoimmune disease; or history of allogeneic tissue/organ transplantation, stem cell or bone marrow transplantation, or solid organ transplantation.
* Vaccination of live virus vaccine within 30 days before the first administration of the study drug. Inactivated seasonal influenza vaccine or approved COVID-19 vaccine is allowed.
* Uncontrolled intercurrent illness
* Patients requiring parenteral nutrition within 4 weeks
* Women who are lactating or pregnant.
* Other conditions that in the clinical judgement of the investigator make the patient not suitable for participation in this study.