This phase II trial aimed to assess the efficacy and safety of pemetrexed in patients with pretreated metastatic gastric cancer.

Patients enrolled in this study received pemetrexed 500mg/m2, once every 21 days, until the presence of progressive disease or unacceptable toxicity. All patients took dexamethasone 3.75 mg twice daily, starting from the day before and continuing to the day after the drug administration. Patients were instructed to take oral folic acid 400 mg daily beginning 5 days before the first therapy and until the final therapy.Patients received Vitamin B12 very 3 cycle of chemoherapy. Granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF) or Erythropoietin (EPO) was not allowed, but they could be used when the patients suffered from bone marrow depression.

Inclusion Criteria:

1. histological confirmed inoperable or metastatic adenocarcinoma of the stomach or gastro-esophageal junction
2. age between 18 and 80 years
3. ECOG performance status of 0 to 2
4. life expectancy ≥ 12 weeks
5. has measurable disease by Response Evaluation Criteria in Solid Tumors (RECIST)
6. at least one prior chemotherapy regimen
7. adequate bone marrow function as defined by absolute neutrophil count more than or equal to 2000/mm3
8. platelet count more than or equal to 100,000/mm3 and hemoglobin more than or equal to 8 g/dL
9. adequate renal function defined by creatinine less than or equal to 1.25 × upper limit of normal(ULN) and creatinine clearance more than or equal to 60mL/min,
10. adequate liver function defined by bilirubin less than or equal to 1.0×ULN aspartate transferase(AST) and alanine transferase(ALT) less than or equal to 2.5 ×ULN.

Exclusion Criteria:

1. other primary malignancy
2. symptomatic central nervous system metastasis
3. pregnancy or lactation
4. cardiovascular events such as myocardial infarction in the previous 6 months or congestive heart failure
5. ongoing infection
6. inability or unwillingness to interrupt nonsteroidal anti-inflammatory drugs for 2 days before and after pemetrexed administration unwillingness to take folic acid or vitamin B12 supplementation.