ONO-4538 360 mg solution intravenously for 30 min in every 3 weeks. Oxaliplatin 130 mg/m2 (BSA) solution intravenously for 2 hours once-daily, followed by 20 days off.

Tegafur-gimeracil-oteracil potassium combination drug 40 - 60 mg bid orally in 14 days, followed by 7 days off Each drug will be continued until documented disease progression, discontinuation due to toxicity, withdrawal of consent or the study ends.

ONO-4538 360 mg solution intravenously for 30 min in every 3 weeks. Oxaliplatin 130 mg/m2 (body surface area) solution intravenously for 2 hours once-daily, followed by 20 days off.

Capecitabine 1200 - 2100 mg bid orally in 14 days, followed by 7 days off. Each drug will be continued until documented disease progression, discontinuation due to toxicity, withdrawal of consent or the study ends.

With regard to the ONO-4538 + chemotherapy group, either SOX therapy or CapeOX therapy will be selected as the chemotherapy by the investigator or the subinvestigator, taking into account the condition of each subject.

ONO-4538 360 mg solution intravenously for 30 min in every 3 weeks. Oxaliplatin 130 mg/m2 (body surface area) solution intravenously for 2 hours once-daily, followed by 20 days off.

Tegafur-gimeracil-oteracil potassium combination drug 40 - 60 mg bid or Capecitabine 1000 mg/ m2 (body surface area) bid orally in 14 days, followed by 7 days off.

Each drug will be continued until documented disease progression, discontinuation due to toxicity, withdrawal of consent or the study ends.