Inclusion Criteria:

          -  Histological confirmation of advanced biliary tract cancers including cancers
             originating in the gallbladder who have received at least one line of systemic
             anticancer therapy

               -  Note: Patients who have either progressed on or are intolerant to the prior
                  therapy can be included in this study

          -  Measurable disease as defined by Response Evaluation Criteria in Solid Tumors (RECIST)
             criteria

               -  NOTE: Tumor lesions in a previously irradiated area are not considered measurable
                  disease. Disease that is measurable by physical examination only is not eligible

          -  Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 or 1

          -  Absolute neutrophil count (ANC) >= 1500/mm^3 (=< 21 days prior to registration)

          -  Platelet count >= 100,000/mm^3 (=< 21 days prior to registration)

          -  Total bilirubin =< 1.5 x upper limit of normal (ULN) (=< 21 days prior to
             registration)

          -  Aspartate transaminase (AST) or alanine transaminase (ALT) =< 3 x ULN (=< 21 days
             prior to registration)

          -  Creatinine =< 1.5 x ULN (=< 21 days prior to registration)

          -  Negative pregnancy test done =< 7 days prior to registration, for persons of
             childbearing potential only

          -  Provide written informed consent

          -  Willing to return to enrolling institution for follow-up (during the active monitoring
             phase of the study)

          -  Willingness to provide mandatory blood and tissue specimens for correlative research

        Exclusion Criteria:

          -  Any of the following because this study involves an agent that has potential
             genotoxic, mutagenic and teratogenic effects:

               -  Pregnant persons

               -  Nursing persons

               -  Persons of childbearing potential who are unwilling to employ adequate
                  contraception for at least 3 months after the last dose of the study drug

          -  Co-morbid systemic illnesses or other severe concurrent disease which, in the judgment
             of the investigator, would make the patient inappropriate for entry into this study or
             interfere significantly with the proper assessment of safety and toxicity of the
             prescribed regimens

          -  Immunocompromised patients and patients known to be human immunodeficiency virus (HIV)
             positive and currently receiving antiretroviral therapy

               -  NOTE: Patients known to be HIV positive, but without clinical evidence of an
                  immunocompromised state, are eligible for this trial

          -  Uncontrolled intercurrent illness including, but not limited to, ongoing or active
             infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac
             arrhythmia, or psychiatric illness/social situations that would limit compliance with
             study requirements

          -  Receiving any other investigational agent which would be considered as a treatment for
             the primary neoplasm =< 21 days prior to registration

          -  Receiving any anticancer therapy for biliary tract cancer =< 21 days prior to
             registration

          -  Other active malignancy requiring treatment in =< 6 months prior to registration

               -  EXCEPTIONS: Non-melanotic skin cancer or carcinoma-in-situ of the cervix

               -  NOTE: If there is a history of prior malignancy, they must not be receiving other
                  specific treatment for their cancer

          -  History of myocardial infarction =< 6 months prior to registration, or congestive
             heart failure requiring use of ongoing maintenance therapy for life-threatening
             ventricular arrhythmias

          -  Previous treatment with irinotecan or irinotecan-based chemotherapy for biliary tract
             cancers