Phase I/II Trial of Pemigatinib in Combination With Atezolizumab and Bevacizumab for Treatment of Advanced Cholangiocarcinoma With FGFR2 Fusion

Inclusion Criteria: * Ability to understand and willingness to sign informed consent. * Age ≥18 years. * Has histologically confirmed metastatic or advanced unresectable cholangiocarcinoma. * Has disease that is measurable per the RECIST v1.1. * Has at least one measurable target lesion. * Has FGFR2 fusion or rearrangement in tumor tissue, as determined by CLIA-validated genomic testing of a tumor tissue specimen (DNA-based or RNA-based). * Is refractory to, has demonstrated intolerance to, had received, or has refused access to, the 1st line systemic therapy including gemcitabine-based therapy with or without immunotherapy including durvalumab or pembrolizumab. Participants who discontinued available standard therapy due to toxicity must have continued evidence of measurable disease. * Has available a formalin-fixed, paraffin-embedded primary tumor sample. * Is able to take oral medication and to comply with protocol procedures and scheduled visits.. * Has Eastern Cooperative Oncology Group performance status of 0 or 1 * Has adequate hematologic and end-organ function, defined by the following laboratory test results, obtained within 14 days prior to initiation of study treatment: * Absolute neutrophil count (ANC) ≥ 1.5 × 109/L (1500/µL) without granulocyte colony-stimulating factor support * Lymphocyte count ≥ 0.5 x 109/L (500/µL) * Platelet count ≥ 100 × 109/L (100,000/µL) without transfusion * Hemoglobin ≥ 90 g/L (9 g/dL), participants may be transfused to meet this criterion. * Aspartate amino transferate (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) ≤ 2.5 × upper limit of normal (ULN), with the following exceptions: * Participants with documented liver metastases: AST and ALT ≤ 5 × ULN * Participants with documented liver or bone metastases: ALP ≤ 5 × ULN * Serum bilirubin ≤ 1.5 × ULN with the following exception: * Participants with known Gilbert disease: serum bilirubin ≤ 3 × ULN * Serum creatinine ≤ 1.5 × ULN * Serum albumin ≥ 25 g/L (2.5 g/dL) * For participants not receiving therapeutic anticoagulation: international normalized ratio (INR) or activated partial thromboplastin time (aPTT) ≤ 1.5 × ULN. For patients on anticoagulation, those on therapeutic anticoagulation over 2 weeks are eligible. * Has a negative human immunodeficiency virus (HIV) test at screening with the following exception: participants with a positive HIV test at screening are eligible provided they are stable on anti-retroviral therapy, have a CD4 count ≥ 200 and have an undetectable viral load. * Must meet institutional standards for proteinuria * Has a negative hepatitis B surface antigen (HBsAg) test at screening (unless participant has chronic HBV on anti-viral therapy) * Has a negative total hepatitis B core antibody (HBcAb) test at screening, or positive total HBcAb test followed by a negative hepatitis B virus (HBV) DNA test at screening (unless patient has chronic HBV on anti-viral therapy) * The HBV DNA test will be performed only for participant who have a negative HBsAg test and a positive total HBcAb test. * Participants with chronic HBV on antiviral therapy or HCV participants who have completed curative anti-viral therapy can be included. * For women of childbearing potential: agrees to remain abstinent (refrain from heterosexual intercourse) or to use contraceptive methods, and agrees to refrain from donating eggs, as defined below: * Women must remain abstinent or use contraceptive methods with a failure rate of \< 1% per year during the treatment period and for 6 months after the final dose of atezolizumab/pemigatinib/bevacizumab. Women must refrain from donating eggs during this same period. * A woman is considered to be of childbearing potential if she is postmenarchal, has not reached a postmenopausal state (≥ 12 continuous months of amenorrhea with no identified cause other than menopause), and has not undergone surgical sterilization (removal of ovaries and/ or uterus). The definition of childbearing potential may be adapted for alignment with local guidelines or requirements. * Examples of contraceptive methods with a failure rate of \< 1% per year include bilateral tubal ligation, male sterilization, hormonal contraceptives that inhibit ovulation, hormone-releasing intrauterine devices, and copper intrauterine devices. * The reliability of sexual abstinence should be evaluated in relation to the duration of the clinical trial and the preferred and usual lifestyle of the participant. Periodic abstinence (e.g., calendar, ovulation, symptothermal, or postovulation methods) and withdrawal are not adequate methods of contraception. * For men: agrees to remain abstinent (refrain from heterosexual intercourse) or use a condom, and agrees to refrain from donating sperm, as defined below: * With a female partner of childbearing potential or pregnant female partner, men must remain abstinent or use a condom during the treatment period and for 6 months after the final dose of atezolizumab/pemigatinib/ bevacizumab to avoid exposing the embryo. Men must refrain from donating sperm during this same period. * The reliability of sexual abstinence should be evaluated in relation to the duration of the clinical trial and the preferred and usual lifestyle of the participant. Periodic abstinence (e.g., calendar, ovulation, symptothermal, or postovulation methods) and withdrawal are not adequate methods of preventing drug exposure. Exclusion Criteria: * Received prior chemotherapy, biologic therapy, immunotherapy, or investigational agent within 3 weeks prior to initiation of study medications. * Had previous treatment with selective FGFR inhibitors including erdafitinib, infigratinib, or futibatinib. * Had prior therapy with any VEGFR-targeting agent targeting including bevacizumab, ramucirumab, pazopanib, lenvatinib, and other anti-angiogenesis inhibitors. * Has a history and/or has current evidence of extensive tissue calcification including, but not limited to, the soft ti