Inclusion Criteria:

          -  Diagnosis of AML confirmed by review of bone marrow pathology at the University of
             Florida.

          -  Patients with relapsed and /or refractory AML who: failed to achieve complete
             remission (CR) or complete remission with incomplete blood count recovery (CRi) after
             at least one cycle of induction chemotherapy and not suitable for a second cycle of
             standard intensive chemotherapy; or who have progressed after 1 cycle of
             hypomethylating agent or intolerant to hypomethylating agent therapy and not suitable
             for standard induction chemotherapy regimens; or have relapsed after any duration of
             response.

          -  Per the treating physician, the subject must have a life expectancy of >= 4 weeks.

          -  Subject performance status must be Eastern Cooperative Oncology Group (ECOG) 0, 1, or
             2.

          -  Subject must have a total bilirubin <= 2 mg/dL and aspartate aminotransferase (AST)
             and alanine aminotransferase (ALT) <= 2.5 times the upper limit of normal.

          -  Subject must have serum creatinine < 2 mg/dL.

          -  Females of child-bearing potential may participate, provided they meet the following
             conditions: Must agree to use physician-approved contraceptive methods throughout the
             study and for 6 months following the last dose of ciprofloxacin and/or etoposide; Must
             have a negative serum pregnancy test within 7 days prior to beginning treatment on
             this study.

          -  Males with female partners of child-bearing potential must agree to use
             physician-approved contraceptive methods throughout the study and should avoid
             conceiving children for 6 months following the last dose of ciprofloxacin and/or
             etoposide.

          -  Must provide written informed consent and be willing to comply with all study-related
             procedures.

        Exclusion Criteria:

          -  History of allergic or significant adverse reaction [e.g., anaphylaxis, prolonged QTc,
             or severe tendonitis] to ciprofloxacin or etoposide.

          -  Acute promyelocytic leukemia (APL) with t(15;17).

          -  Prolonged baseline QTc, defined as QTc interval > 470 msec in women and > 450 msec in
             men, or > 480 msec in subjects with a bundle branch block.

          -  Uncontrolled, clinically significant infection. Subjects with a fever (temperature >=
             38.3) thought to be related to leukemia are eligible assuming that blood cultures are
             negative during the 7 days prior to Cycle 1 Day 1 and there is no clinical evidence of
             active infection (e.g., negative or stable radiographs and negative physical
             examination).

          -  Ongoing, symptomatic Clostridium difficile infection. Subjects who are asymptomatic
             with negative stool for C. difficile may participate.

          -  Pregnant and or nursing.

          -  History of Myasthenia Gravis.

          -  Treatment with any anticancer therapy (standard or investigational) within 14 days
             prior to the first dose of ciprofloxacin or less than full recovery from the
             clinically significant toxic effects of that treatment. The use of hydroxyurea is
             allowed only during the first 14 days of Cycle 1.