• Written informed consent and HIPAA authorization for release of personal health information prior to registration. NOTE: HIPAA authorization may be included in the informed consent or obtained separately.

• Age ≥ 18 years at the time of consent.

• ECOG Performance Status of 0 or 1 within 7 days prior to Cycle 1 Day 1.

• Body weight of \> 30 kg.

• Histologically diagnosed locally advanced unresectable or metastatic intrahepatic cholangiocarcinoma with FGFR-2 fusion or rearrangement detected by Clinical Laboratory Improvement Act (CLIA)-certified assays including commercial tests (Foundation Medicine, Caris, Tempus, Guardant 360 or other platforms of next generation sequencing will be allowed). AJCC, 8th edition. Subjects with gallbladder cancer or ampulla of Vater carcinoma are not eligible.

• Measurable disease according to RECIST 1.1. Lesions situated in a previously irradiated area are considered measurable if progression has been demonstrated in such lesions.

• Have received gemcitabine cisplatin and durvalumab or another anti-PD-1 Ab for unresectable locally advanced or metastatic cholangiocarcinoma with either disease progression, intolerance to cytotoxic chemotherapy, or have received at least 6 months of therapy with stable disease or partial response. Prior neoadjuvant or adjuvant therapy is permitted if documented disease recurrence occurred ≥ 6 months after the last date of neoadjuvant or adjuvant therapy.

• Demonstrate adequate organ function as defined below. All screening labs to be obtained within 28 days prior to registration.

‣ Absolute Neutrophil Count (ANC): ≥1500/µL

⁃ Hemoglobin (Hgb): ≥ 9 g/dL; Criteria must be met without erythropoietin dependency and without packed red blood cell (pRBC) transfusion within last 2 weeks.

⁃ Platelet (PLT): ≥ 100 000/µL

⁃ Calculated creatinine clearance: \>40 mL/min

⁃ Bilirubin: ≤ 1.5 × upper limit of normal (ULN) This will not apply to patients with confirmed Gilbert's syndrome (persistent or recurrent hyperbilirubinemia that is predominantly unconjugated in the absence of hemolysis or hepatic pathology), who will be allowed only in consultation with the sponsor-investigator.

⁃ Aspartate aminotransferase (AST): ≤ 2.5 × institutional upper limit of normal unless liver metastases are present, in which case it must be ≤ 5x ULN

⁃ Alanine aminotransferase (ALT): ≤ 2.5 × institutional upper limit of normal unless liver metastases are present, in which case it must be ≤ 5x ULN

⁃ International Normalized Ratio (INR) or Prothrombin Time (PT) Activated Partial Thromboplastin Time (aPTT): ≤ 1.5 × ULN unless subject is receiving anticoagulant therapy as long as PT or aPTT is within therapeutic range of intended use of anticoagulants

• Females of childbearing potential must have a negative serum pregnancy test at screening.

⁃ Females of childbearing potential who are sexually active with a male able to father a child must be willing to use an effective method(s) of contraception. Males able to father a child who are sexually active with female of childbearing potential must be willing to use an effective method(s) of contraception.

⁃ Patient is willing and able to comply with the protocol for the duration of the study including undergoing treatment and scheduled visits and examinations including follow up.

⁃ Must have a life expectancy of at least 12 weeks.