Findings of preclinical and clinical trials in colorectal cancer have shown promising antitumour effects of the co-formulation trifluridine/tipiracil and VEGF inhibition. We aimed to investigate the safety and activity of trifluridine/tipiracil and ramucirumab for previously treated advanced gastric cancer.We did an open-label, single-arm, two-cohort, phase 2 study at eight centres in Japan. We enrolled patients with unresectable advanced gastric cancer or gastro-oesophageal junction adenocarcinoma. Cohort A included patients previously treated with one line of chemotherapy without ramucirumab and cohort B included patients previously treated with two to four lines of chemotherapy, including ramucirumab. Patients received trifluridine/tipiracil (35 mg/m2) orally twice daily on days 1-5 and days 8-12 of each 28-day treatment cycle, plus intravenous ramucirumab (8 mg/kg) on days 1 and 15. The primary endpoint was the disease control rate, assessed by investigators and defined as the proportion of patients with a confirmed best overall response, according to Response Evaluation Criteria in Solid Tumors version 1.1. This trial is registered on JapicCTI (JapicCTI-194596) and is ongoing but not recruiting.Between April 8 and Oct 11, 2019, 64 patients were enrolled and included in the safety and activity analyses, 33 in cohort A and 31 in cohort B. In cohort A, the disease control rate was 85% (95% CI 68-95; 28 of 33 patients) and in cohort B it was 77% (59-90; 24 of 31 patients). Common treatment-related adverse events of grade 3 or worse were neutrophil count decreased (27 [82%] in cohort A and 23 [74%] in cohort B), white blood cell count decreased (eight [24%] and seven [23%]), and platelet count decreased (eight [24%] and four [13%]). Serious treatment-related adverse events were recorded in three patients in cohort A (fatigue and neutrophil count decreased; large intestine perforation; and febrile neutropenia, platelet count decreased, and anaemia). No patients in cohort B had a serious treatment-related adverse event, and no treatment-related deaths were reported in either cohort.Trifluridine/tipiracil and ramucirumab showed an acceptable safety profile and clinical activity in patients with previously treated advanced gastric cancer regardless of previous ramucirumab exposure.Taiho Pharmaceutical and Eli Lilly.