Inclusion Criteria:

1. Male or female patients * 18 years of age

2. Accelerated phase of CML defined as the presence of one or more of the following:

- percentage of blasts in blood or bone marrow * 15% but < 30%

- percentage of blasts plus promyelocytes in the peripheral blood or bone marrow *
30% (providing that < 30% blasts are present in the bone marrow)

- peripheral basophils * 20%

- thrombocytopenia < 100 x 109/L unrelated to therapy These criteria must be met
within 4 weeks of administration of first dose of trial treatment.

3. Blastic phase of CML defined as the presence of one or more of the following:

- percentage of blasts in blood or bone marrow * 30%

- percentage of blasts and promyelocytes in blood or bone marrow * 50%

- documented extramedullary blast involvement (skin, lymph node, bone, lung).

4. Voluntary written informed consent.

Exclusion Criteria:

1. Patients of childbearing potential wihout a negative pregnancy test prior to the
initiation of study drug. Barrier contraceptive precautions are to be used throughout
the trial in both sexes.

2. Patients with an ECOG Performance Status Score ** 3 (see Section 7.2.1)

3. Creatinine levels more than 2 x's the ULN at the laboratory where the analysis was
performed.

4. Total serum bilirubin more than 1.5 x's the upper limit of the normal range (ULN) at
the laboratory where the analyses were performed; in patients with clinically
suspected leukemic involvement of the liver, total bilirubin more than 3 x's the ULN

5. AST (SGOT) or ALT (SGPT) more than 3 x's the upper limit of the normal range (ULN) at
the laboratory where the analyses were performed; in patients with clinically
suspected leukemic involvement of the liver, AST and ALT more than 5 x's the ULN

6. Patients receiving treatment with interferon-alpha within 48 hours of Day 1.

7. Patients receiving treatment with hydroxyurea within 24 hours of Day 1

8. Patients receiving treatment with homoharringtonine within 14 days of Day 1

9. Patients receiving treatment with low-dose cytosine arabinoside (< 30 mg/m2 every 12
to 24 hours administered daily) within seven days of Day 1

10. Patients receiving treatment with moderate dose cytosine arabinoside (100-200 mg/m2
for 5 to 6 days) within 14 days of Day 1.

11. Patients receiving treatment with high-dose cytosine arabinoside (1-3 g(m2 every 12
to 24 hours for six to 12 doses) within 28 days of Day 1.

12. Patients receiving anthracyclines, mitoxantrone, etoposide, methotrexate or
cyclophosphamide within 21 days of Day1.

13. Patients receiving busulfan within six weeks of Day 1.

14. Patients receiving anti-leukemic agents not included in Exclusion Criteria 6-13
should not begin treatment with STI571 until sufficient time has elapsed for
potential recovery to have occurred in the nadir in blood counts. In practice, a full
recovery of blood counts may not be possible due to progression of the underlying
disease.

15. Patients receiving any hematopoietic stem cell transplantation and who have not
achieved full hematopoietic recovery following the transplant

16. Patients receiving any other investigational agents within 28 days of Day 1.

17. Patients with Grade ¾ cardiac disease.

18. Patients with any serious concomitant medical condition

19. Patients with a history of non-compliance to medical regimens or who are considered
potentially unreliable.

20. Patients with a prior diagnosis of accelerated or blastic phase who are in remission
and do not fit inclusion criteria, are not eligible.

21. Patients who are likely to be submitted to any procedure of stem cell transplantation
before the end of the treatment (6 months), are not eligible.