AMD3100 With Busulfan, Fludarabine and Thymoglobulin for Allogeneic Stem Cell Transplant for AML and MDS

Inclusion Criteria:

* Diagnosis of AML past first remission, (i.e., in first or subsequent relapse, in second or greater remission or primary induction failure) or MDS with intermediate or high risk International Prognostic Scoring System (IPSS) score (71) or having failed to respond or recurred after chemotherapy.
* WBC \<20 x 10e9/l.
* Patients should have a histocompatible, related or unrelated volunteer donor available for a PBSC transplant. A histocompatible donor is defined as HLA matched for at least 9 of 10 HLA A, B, C, DR and DQ antigens by high-resolution DNA technique per departmental routine.
* Patient has not been administered any other systemic chemotherapeutic drug (including Mylotarg) within 21 days prior to trial enrollment. (Hydroxyurea is permitted if indicated to control induction refractory disease, and intrathecal (IT) chemotherapy is allowed if indicated as maintenance treatment for previously diagnosed leptomeningeal disease (LMD), that has been in remission for at least 3 months prior to enrollment on this study).
* Zubrod performance status \< 2.
* Left ventricular ejection fraction \>45%. No uncontrolled arrhythmias or uncontrolled symptomatic cardiac disease. This should be performed within 28 days prior to study entry.
* No symptomatic pulmonary disease. Forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and diffusion capacity of carbon monoxide (DLCO) \> 50 % of expected, corrected for hemoglobin. This should be performed within 28 days prior to study entry.
* Serum creatinine \<1.5 mg/dl.
* Serum glutamic pyruvic transaminase (SGPT) \<200 IU/ml. Total serum bilirubin and alkaline phosphatase \<2.5 times laboratory standard upper limit of normal (ULN), or considered not clinically significant by the protocol PI.
* Patient or patient's legal representative able to sign informed consent.

Exclusion Criteria:

* HIV positive.
* Female patient who is pregnant (negative pregnancy test is required for all women of child-bearing-potential).
* Pleural/pericardial effusion or ascites estimated \> 1 liter.
* Uncontrolled infection. Patients considered to have uncontrolled infections including active fungal pneumonia are not eligible. Patients with infections or pulmonary infiltrates responding to antimicrobial treatment are eligible. Infectious Disease consultation should be obtained if indicated. These cases should be discussed with the Protocol PI who is the final arbiter of eligibility.
* Evidence of chronic active hepatitis or cirrhosis.
* Patients should not have received investigational agent(s) or intensive chemotherapy within 21 days of starting the study treatment regimen.