2. Patients must have relapsed/refractory leukemias for which no standard therapies exist. Patients with poor-risk myelodysplasia (MDS) and chronic myelomonocytic leukemia (CMML) who failed prior therapy are also candidates for this protocol. Relapsed/refractory leukemias include acute non-lymphocytic leukemia (AML) by World Health Organization (WHO) classification (i.e. >/= 20% blasts), acute lymphocytic leukemia (ALL), or chronic myelogenous leukemia (CML) in blast crisis. Patients with CML who are resistant to at least two tyrosine kinase inhibitors and have no standard stem cell transplant option are also eligible.