Sintilimab Plus FOLFIRI as Salvage Therapy for Patients With Advanced Gastric Cancer

sintilimab 3mg/kg for patients with body weight\<60kg or 200mg for patients with body weight ≥ 60kg, plus irinotecan 180mg/m2 intravenous infusion, leucovorin folinate 400mg/m2 intravenous infusion and fluorouracil 400mg/m2 intravenous injection followed by 2400mg/m2 intravenous infusion for 48 hours, repeated every two weeks.