A Study of Tumor-Treating Fields in Combination With Durvalumab and Gemcitabine/Cisplatin in Biliary Tract Cancers

Inclusion Criteria: 1. Willing and able to provide written informed consent for the trial. 2. Male or female patients between the ages of 18 and 75 years (including 18 and 75 years). 3. Body weight \> 30 kg. 4. Histologically confirmed, unresectable adenocarcinoma of the biliary tract, including cholangiocarcinoma (intrahepatic or extrahepatic) and gallbladder carcinoma. 5. Patients with the previously untreated disease if unresectable or metastatic at initial diagnosis will be eligible. 6. Patients with recurrent disease \>6 months after curative surgery or \>6 months after the completion of adjuvant therapy (chemotherapy and/or radiation) will be eligible (but he/she does not receive systemic treatment as the first-line therapy). 7. At least 1 measurable lesion that qualifies as a RECIST 1.1 Target Lesion (TL) at baseline. 8. ECOG PS of 0 or 1. 9. Life expectancy ≥12 weeks at the time of screening. 10. No prior exposure to immune-mediated therapy, including, but not limited to, other anti-CTLA-4, anti-PD-1, anti-PD-L1, and anti-PD-L2 antibodies, excluding therapeutic anticancer vaccines. 11. Patients must have adequate organ function as indicated by the following laboratory values: Hemoglobin ≥9.0 g/dL; Absolute neutrophil count ≥1.5 ×109/L; Platelet count ≥100 ×109/L. No blood transfusion, granulocyte colony-stimulating factor (G-CSF), filgrastim and other drugs are used within 2 weeks before the examination. Serum bilirubin ≤2.0 × the upper limit of normal (ULN); This will not apply to patients with confirmed Gilbert's syndrome. Any clinically significant biliary obstruction should be resolved before treatment. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤2.5 × ULN; for patients with hepatic metastases, ALT and AST ≤5 × ULN. Creatinine clearance (CL) \>50 mL/min per 24-hour urine or as calculated by Cockroft and Gault formula (using actual body weight). 12. Patients (women of childbearing potential and males with fertile female partners) must be willing to use the currently accepted reliable contraception method from the time of screening throughout the total duration of the study treatment and the drug washout period (180 days after the last dose of GemCis or 90 days after the last dose of durvalumab monotherapy). These measures include, but are not limited to, oral or implantable injections of hormonal contraceptives; intrauterine birth control ring or placement of IUS intrauterine device); or use of barrier methods such as condoms or septum and spermicide products. Postmenopausal women over 50 years of age must have been amenorrheic for at least 12 months to be considered non-childbearing potential. 13. Patients with HBV infection (as characterized by positive hepatitis B surface antigen \[HBsAg\] and/or anti-hepatitis B core antibodies (anti-HBc) with detectable HBV deoxyribonucleic acid (DNA) \[above the limit of detection per local laboratory\]) must receive antiviral therapy prior to treatment per institutional practice to ensure adequate viral suppression. Patients must remain on antiviral therapy for the study duration and for 6 months after the last dose of study treatment. Patients who test positive for anti-HBc with undetectable HBV DNA (under the limit of detection per local laboratory) do not require antiviral therapy unless HBV DNA reaches detectable limits per local laboratory during the course of treatment. Patients with active co-infection of HBV and HCV as evidenced by positive anti-HCV antibody and actively co-infected with HBV and hepatitis D virus are not eligible. 14. Able to operate TTF device independently or with the help of a caregiver. Exclusion Criteria: 1. Patients previously received systemic treatment as the first-line therapy. 2. Ampullary carcinoma. 3. History of allogeneic organ transplantation. 4. Active or prior documented autoimmune or inflammatory disorders (including inflammatory bowel disease \[e.g., colitis or Crohn's disease\], diverticulitis \[with the exception of diverticulosis\], systemic lupus erythematosus, Sarcoidosis syndrome, or Wegener syndrome \[granulomatosis with polyangiitis, Graves' disease, rheumatoid arthritis, hypophysitis, uveitis, etc.\]). The following are exceptions to this criterion: Patients with vitiligo or alopecia; Patients with hypothyroidism (e.g., following Hashimoto syndrome) are stable on hormone replacement; Any chronic skin condition that does not require systemic therapy; Patients without active disease in the last 5 years may be included but only after consultation with the investigator/ Study Physician; Patients with celiac disease controlled by diet alone. 5. Uncontrolled intercurrent illness, including, but not limited to, symptomatic congestive heart failure, uncontrolled hypertension, unstable angina pectoris, uncontrolled cardiac arrhythmia, active interstitial lung disease (ILD), serious chronic gastrointestinal conditions associated with diarrhea, or psychiatric illness/social situations that would limit compliance with study requirement, substantially increase the risk of incurring AEs, or compromise the ability of the patient to give written informed consent. 6. History of another primary malignancy, except for: Malignancy was treated with curative intent and with no known active disease ≥5 years before the first dose of the investigational product (IP) and of low potential risk for recurrence; Adequately treated non-melanoma skin cancer or lentigo maligna without evidence of disease; Adequately treated carcinoma in situ without evidence of disease. 7. History of leptomeningeal carcinomatosis. 8. History of active primary immunodeficiency. 9. Active infection, including tuberculosis (clinical evaluation that includes clinical history, physical examination and radiographic findings, and tuberculosis testing in line with local practice), or human immunodeficiency virus (positive HIV 1/2 antibodies). 10. Any unresolved toxicity NCI CTCAE Grade ≥2 from a previous anticancer