Imatinib Mesylate, Busulfan, Fludarabine, and Antithymocyte Globulin for CML Patients

Primary Objective:

To estimate the probability of molecular complete remission at one year for the described sequential treatment approach, with nonablative hematopoietic transplantation, post transplant imatinib mesylate and donor lymphocyte infusion, in patients with Ph-positive Chronic Myelogenous Leukemia (CML) not in blastic transformation.

Secondary Objective:

Response to post transplant Imatinib mesylate therapy for 12 weeks as treatment of residual disease, response to donor lymphocyte infusion (DLI) for residual disease following imatinib mesylate therapy, as well as engraftment, toxicity, disease free survival and survival, effect of busulfan pharmacokinetics on study outcome.

Patients will have blood and bone marrow tests performed as well as chest and sinus X-rays and tests of their heart and lung function. Approximately 5 tablespoons of blood will be drawn.

All patients in this study will receive imatinib mesylate by mouth for 9 days, unless the patient is known to be allergic or have symptomatic intolerance to the drug, or if the leukemia has failed to respond to imatinib. Fludarabine 40 mg/m2 by vein for 4 days (days -5 to -2), busulfan 130 mg/m2 by vein for 2 days (days -3 and -2), and ATG (Antithymocyte Globulin) 2.5 mg/kg by vein for 3 days (-3,-2 and -1).

Patients will then receive the donor bone marrow or blood stem cells by vein over approximately one hour on day 0.

After the infusion of the donor cells, you will receive immunosuppressive therapy with tacrolimus and methotrexate to decrease the risk of developing graft-vs-host disease (GvHD).

Patients will need frequent blood tests to monitor their counts and blood chemistries. This is generally done daily while in hospital and at least twice per week for the first 100 days post transplant. You may need frequent blood transfusions and may have to be admitted to the hospital to receive antibiotics if they develop fever. Bone marrow will be examined frequently beginning four weeks after treatment to evaluate response to treatment; Blood and bone marrow exams are to be performed at one, two three, six, 12 and 18 months post transplant and yearly thereafter for 5 years. To collect a bone marrow sample, an area of the hip or chest bone is numbed with anesthetic and a small amount of bone marrow is withdrawn through a large needle.

Patients in whom treatment produces a remission, in which no sign of the leukemia can be detected, will receive no further therapy unless the leukemia recurs. Patients with evidence of leukemia after 3 months from the transplant will receive additional treatment with imatinib mesylate; those with detectable leukemia after an additional 3 months may receive an infusion of immune cells from the transplant donor.

If there is evidence of leukemia after the transplant, you will receive additional treatment with imatinib mesylate. If leukemia cells can still be detected, additional donor immune cells will be given to you by vein.

Patients are considered on the study for 5 years after the transplant.

A total of 90 patients will take part in this study. All will be enrolled at M. D. Anderson.

Eligibility Criteria:
Inclusion Criteria:

1. Diagnosis of Ph+ chronic myelogenous leukemia (CML) in first chronic phase without a complete hematologic response after 3 months of Imatinib mesylate therapy, or \>=35% Ph+ cells despite \> 6 months of Imatinib mesylate treatment, or after disease progression from a complete or partial response. Any patient with accelerated phase or blast crisis who achieves a subsequent chronic phase is eligible. Patients must have an HLA matched related or unrelated donor or one antigen mismatched related donor.
2. Patients should be less than 70 years of age. Patients less than 30 years of age who achieve a hematologic remission with imatinib therapy are eligible regardless of cytogenetic response.
3. Patients are stratified as Group 1: First chronic phase, Group 2 Accelerated phase or blast crisis that achieved a hematologic remission with imatinib mesylate-based treatment.

Exclusion Criteria:

1. Zubrod Performance Scale (PS) \>=2, uncontrolled infection, Creatinine \> 2.0 mg/dl; Ejection fraction \< 40%; Carbon Monoxide Diffusing Capacity (DLCO) \< 45% of predicted; Serum bilirubin \> 2 gm/dl; GPT (Glutamic-pyruvic transaminase) or GOT (glutamic-oxaloacetic transaminase)\> 3 times normal values. Patients should not be human immunodeficiency virus (HIV) seropositive or pregnant.
2. Patients should not have progressed to accelerated phase or blast crisis while receiving imatinib mesylate containing therapy.