Inclusion Criteria:  Have histologically- or cytologically-confirmed diagnosis of metastatic gastric adenocarcinoma in the stomach and gastroesophageal junction that are refractory to at least two lines of treatment. Have a performance status of 0-1 on the ECOG Performance Scale. Have measurable disease at least one investigator-assessed measurable disease per RECIST v1.1 Have adequate organ functions  Exclusion Criteria:  Prior ALK5 inhibitor treatment Current or prior use of immunosuppressive medication within 14 days before the first dose of study drugs Patients weighing <30kg