Inclusion Criteria:  Cohort 1 and 2: histologically or cytologically confirmed locally advanced or metastatic gastric cancer or gastroesophageal junction adenocarcinoma. Cohort 3: histologically or cytologically confirmed locally advanced or metastatic solid tumors other than gastric cancer (GC), gastroesophageal junction adenocarcinoma (GEJ), cholangiocarcinoma (CHOL) and urothelial carcinoma (UC). Cohort 1 and 2: failed 2nd line or above therapy with locally advanced or metastatic gastric cancer or gastroesophageal junction adenocarcinoma. Cohort 3: Subjects must have failed established standard medical anti-cancer therapies for a diagnosed tumor or have been intolerant to such therapy, or no standard therapy, or in the opinion of the Investigator have been considered ineligible for a particular form of standard therapy on medical grounds (except GC, GEJ, CHOL, and UC). Cohort 1: willing to do tumor biopsy for FGFR2 gene amplification via FISH test at central lab; Cohort 2 and 3: previous document proof of FGFR1, FGFR2, or FGFR3 fusions/rearrangements and activating mutations (FISH/NGS/PCR results could be accepted) presented by local laboratory or central laboratory. Measurable disease by RECIST v1.1. Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1.  Exclusion Criteria:  To be eligible for the study, subjects must not meet any of the following criteria:  History of other primary malignancies within 3 years except adequately treated in situ carcinoma of the cervix or nonmelanoma carcinoma of the skin or any other curatively treated malignancy that is not expected to require treatment for recurrence during the course of the study. Previous or current treatment of a mitogen-activated protein kinase (MAPK) or selective FGFR inhibitor. Any known hypersensitivity to Infigratinib or its excipients. Subjects with symptomatic central nervous system metastasis. History and/or current evidence of extensive tissue calcification. Amylase or lipase >2.0 × ULN. Abnormal calcium or phosphorus, or calcium-phosphorus product ≥55 mg2/dL2. Current evidence of endocrine alterations of calcium/phosphate homeostasis. Current evidence of corneal or retinal disorder/keratopathy. Currently receiving or planning to receive treatment with agents or foods that are known strong inducers or inhibitors of CYP3A4 and medications which increase serum phosphorus and/or calcium concentration during this study. Subjects are not permitted to receive enzyme-inducing anti-epileptic drugs.