A Study of TAS-120 in Patients With Advanced Solid Tumors

Open to people ages 18 years and up

1. Provide written informed consent
2. Age ≥ 18 years of age
3. Has histologically or cytologically confirmed, locally advanced or metastatic cancer
4. The following specific criteria for each study portion

Phase 1 (Dose Escalation):

- Patients with any type of solid tumor - Disease progression following standard therapies or intolerant to prior standard therapies

Phase 1 (Dose Expansion)

- Have at least one FGF/FGFR aberration - Disease progression following standard therapies or were intolerant to prior standard therapies (including prior FGFR inhibitors). - Have measurable disease as defined by Response Evaluation Criteria in Solid Tumors (RECIST) guidelines (version 1.1, 2009) for advanced solid tumors or RANO criteria (2010) for brain tumors. - Patients with any of the following tumor types - Patients with intrahepatic or extrahepatic CCA harboring FGFR2 gene fusions or other FGFR2 aberrations - Patients with primary CNS tumors - Patients with advanced urothelial carcinoma with FGFR3 fusions or FGFR3 activating mutations - Patients with breast cancer or gastric cancer - Patients with other solid tumor types harboring FGFR gene fusions or activating mutations - Patients with solid tumor types and other FGF/FGFR alterations not listed above

Phase 2

- Patients with iCCA and FGFR2 gene rearrangements (incl fusions) - Have been treated with at least one prior systemic gemcitabine and platinum-based chemotherapy - Must have documentation of radiographic progression of disease - No prior FGFR inhibitor - Measurable disease as defined by Response Evaluation Criteria in Solid Tumors (RECIST) guidelines (version 1.1, 2009)

1. Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1
2. Adequate organ function.

1. History and/or current evidence of clinically significant non-tumor related alteration of calcium-phosphorus homeostasis.
2. History and/or current evidence of clinically significant ectopic mineralization/calcification.
3. History and/or current evidence of clinically significant retinal disorder
4. A serious illness or medical condition(s)
5. Pregnant or breast-feeding female