Inclusion Criteria:

1. Patients with MDS with >/= 5% blasts or IPSS risk group intermediate (1 or 2) or high (i.e., IPSS score 0.5 or higher).
2. Patients must have failed prior therapy with either chemotherapy (e.g., ara-C-based chemotherapy, etc) or biologic agents (e.g., hypomethylating agents, arsenic, thalidomide, CC5013, farnesyl transferase inhibitors, ATG, cyclosporine, etc).
3. Age >/= 18 years. Because no dosing or adverse event data are currently available on the use of Gimatecan in patients <18 years of age, children are excluded from this study but will be eligible for future pediatric single-agent trials, if applicable.
4. ECOG performance status 0-2.
5. Patients must have normal organ function as defined below: 1) Total bilirubin: </= 1.5 x institutional upper limit of normal; 2) ALT(SGPT): </= 2.5 x institutional upper limit of normal; 3) Creatinine: </= 1.5 x institutional upper limit of normal.
6. The effects of Gimatecan on the developing human fetus at the recommended therapeutic dose are unknown. For this reason women of child-bearing potential (ie, not post-menopausal for at least 12 months and not surgically sterile) and men must agree to use double-barrier contraception prior to study entry, for the duration of study participation, and for 3 months following discontinuation of study treatment. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately.
7. Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

1. Patients who have received only supportive care (transfusions and/or hematopoietic growth factors) for MDS.
2. Patients who have had chemotherapy or radiotherapy within 4 weeks or 5 half-lives of the agent in question (6 weeks for nitrosoureas or mitomycin C), whichever is greater, prior to entering the study or those who have not recovered to at least grade 1 from adverse events due to agents administered more than 4 weeks earlier. The use of hydroxyurea is allowed up to 48 hours prior to the start of therapy with Gimatecan.
3. Uncontrolled intercurrent illness including, but not limited to, active uncontrolled infection, symptomatic congestive heart failure, unstable angina pectoris, symptomatic cardiac arrhythmia requiring and not responding to medical intervention, or psychiatric illness/social situations that would limit compliance with study requirements.
4. Women who are pregnant or breast-feeding.