Key Inclusion Criteria for all Individuals:

          -  Histologically confirmed advanced or metastatic solid tumor that is measurable or
             nonmeasurable.

          -  Eastern Cooperative Oncology Group (ECOG) performance status score of 0, 1, or 2.

          -  Adequate hematologic counts without transfusional or growth factor support within 2
             weeks of study drug initiation (hemoglobin ≥ 9 g/dL, absolute neutrophil count (ANC)
             ≥1,500/mm^3, and platelets ≥ 100,000/ μL).

          -  Creatinine clearance ≥ 30 mL/min as assessed by the Cockcroft-Gault equation

        Key Inclusion Criteria for Individuals with Normal Hepatic Function:

          -  Normal hepatic function (total bilirubin ≤ ULN and aspartate aminotransferase [AST] ≤
             3.0× ULN).

        Key Inclusion Criteria for Individuals with Moderate Hepatic Function:

          -  Moderate hepatic impairment (1.5 × ULN < total bilirubin < 3.0 × ULN and any level of
             AST).

          -  For individuals with hepatic encephalopathy, the condition does not, in the
             Investigator's opinion, interfere with the individual's ability to provide an
             appropriate informed consent.

        Key Exclusion Criteria for all Individuals:

          -  Have poor venous access

          -  Donated or lost 500mL or more of blood volume (including plasmapheresis) to plans to
             donate during the study

          -  Have had a prior anticancer biologic agent within 4 weeks prior to Day 1 or have had
             prior chemotherapy, targeted small molecule therapy, or radiation therapy within 2
             weeks prior to Day 1 and who have not recovered (i.e., ≤ Grade 2) from adverse events
             (AEs) at the time of study entry. Individuals participating in observational studies
             are eligible.

          -  Had prior treatment with irinotecan within 4 weeks prior to Day 1

          -  Have not recovered (i.e., ≤ Grade 1) from AEs due to a previously administered agent

          -  Have an active second malignancy

          -  Have known active central nervous system (CNS) metastases and/or carcinomatous
             meningitis. Individuals with previously treated brain metastases may participate
             provided they have stable CNS disease for at least 4 weeks prior to the first dose of
             study drug and all neurologic symptoms have returned to baseline, have no evidence of
             new or enlarging brain metastases, and are taking ≤ 20 mg/day of prednisone or its
             equivalent. All individuals with carcinomatous meningitis are excluded regardless of
             clinical stability.

          -  Have history of cardiac disease

          -  Have active chronic inflammatory bowel disease (ulcerative colitis or Crohn's disease)
             or gastrointestinal (GI) perforation within 6 months of enrollment

          -  Have active serious infection requiring intravenous antibiotics (Contact medical
             monitor for clarification)

          -  High-dose systemic corticosteroids (≥20 mg of prednisone or its equivalent) are not
             allowed within 2 weeks of Check-In. However, inhaled, intranasal, intra-articular, and
             topical steroids are allowed.

          -  Use of strong inhibitor or inducer of UGT1A1

          -  Have a history of Gilbert's disease

        Key Exclusion Criteria for Individuals with Normal Hepatic Impairment:

          -  Must have pre-existing condition interfering with hepatic and/or renal function that
             could interfere with the metabolism and/or excretion of the study drug

        Key Exclusion Criteria for Individuals with Moderate Hepatic Impairment:

          -  Had a clinical exacerbation of liver disease within the 2-week period before
             administration of study drug (i.e., abdominal pain, nausea, vomiting, anorexia, or
             fever)

          -  Had clinically demonstrable, tense ascites

          -  Had evidence of acute viral hepatitis within 1 month prior to administration of study
             drug

          -  Have evidence of hepatorenal syndrome

          -  Individuals with transjugular intrahepatic portosystemic shunt (TIPS) placement.

          -  Have active Stage 3 or 4 encephalopathy