Table 1.

Eligibility criteria.

1. Histologically confirmed advanced or metastatic adenocarcinoma of the stomach and the gastroesophageal junction. 2. Disease progression within 3 months of the last dose of first-line trastuzumab-containing therapy. 3. Patients must have performed a fresh biopsy (at least 8–10 slides with >20% tumor content) at the baseline of study enrollment. 4. At least one measurable and evaluable disease site based on response evaluation criteria in solid tumors (RECIST v1.1). 5. Eastern Cooperative Oncology Group Performance Status (ECOG PS) of 0–1. 6. Age ⩾18, no age upper limit unless patient would be unable to tolerate chemotherapy. 7. An expected survival of more than 3 months. 8. Duration from the last therapy is more than 4 weeks for other cytotoxic agents, surgery, or radiotherapy. 9. Major organ function has to meet the following criteria hemoglobin (Hb)>8 g/dl, platelet count >75 × 109/l, neutrophil count >1.5 × 109/L 10. Absence of pregnancy or breastfeeding. 11. Pregnancy test (serum or urine) must be performed for woman of childbearing age within 7 days before enrolment and the test result must be negative. They shall take appropriate methods for contraception during the study until the 8th week after the last administration of study drug. For men, shall agree to take appropriate methods of contraception during the study until the 8th week after the last administration of study drug. 12. Patients must be accessible to follow-up and management in the treatment center. 13. Patient must voluntarily join the study and sign the informed consent form for the study