The Purpose of This Research Study is to See if Combining Gemcitabine, Cisplatin and Durvalumab Chemotherapy Treatments With a Direct Tumor Therapy Yittrium-90 (Y-90) Will Work Better Together to Shrink Tumors and Control Cancer

Inclusion Criteria: * Adult males and females at least 18 years of age * Histologically and/or cytologically confirmed iCCA that is previously untreated or, if systemic therapy has been rendered for prior disease, has been administered at least 6 months before the development of recurrent or de novo new sites of disease. * Unresectable disease, as deemed by the Inova multidisciplinary tumor board (i.e. disease that cannot be safely resected with negative margins, leaving 2 adjacent segments of liver with intact portal venous and hepatic arterial inflow and intact biliary and hepatic venous outflow with the future liver remnant of sufficient volume to avoid postoperative liver insufficiency) * Measurable disease per RECIST 1.1 at least 2 cm in size * Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1 * Noncirrhotic liver - patients should not have a preexisting diagnosis of cirrhosis either diagnosed via biopsy or with features consistent with cirrhosis on imaging (e.g. shrunken liver with nodularity consistent with cirrhosis). Child-Pugh score must be less than 5. * No evidence of extrahepatic disease, except for regional adenopathy that would be resected as part of a standard oncologic surgical procedure * Adequate organ function as indicated by the following laboratory values (Table 1) * Ability to complete testing in the protocol * Able and willing to consent to protocol Exclusion Criteria: * Female patients who are pregnant or breast-feeding *…