Inclusion Criteria:

- GIST patient considered initially non-resectable as defined by one of the following:

1. when the surgical team considers that the risk of incomplete resection (R1 or
R2) of a GIST is higher than 20%

2. when the resection of a GIST necessitates a highly morbid procedure

3. when a GIST is attached to 3 or more major intra-abdominal structures or to a
major intra-abdominal blood vessel

4. when GIST is considered at very high risk of recurrence. This is the case when
it is a recurrence or when the tumor is in very close contact with a structure
that cannot be resected by surgery or when the patient has metastasis.

- Outpatient is 18 years old or more

- ECOG performance status 0, 1 or 2

- Immunohistochemical confirmation of KIT overexpression must exist at the study entry

- Measurable disease on CT-Scan or MRI (ultrasound and/or operative finding are not
acceptable) and response to RECIST criteria

- Have a life expectancy of at least 6 months

- Be willing and able to comply with the protocol (and surgery if required) for the
duration of the study

- Give written informed consent prior to study-specific screening procedure, with the
understanding that the patient has the right to withdraw from the study at any time
without prejudice

Exclusion Criteria:

- received Imatinib in the past

- received a full course of radiotherapy within 3 months of inclusion in the study. A
short course of radiotherapy to control bleeding is allowed.

- received systemic chemotherapy within 4 weeks of inclusion in the study

- received steroids for less than 4 weeks of inclusion in the study

- pregnant or lactating women

- women of childbearing potential with either a positive or no pregnancy test at
baseline. Postmenopausal women must have been amenorrheic for at least 12 months to
be considered of non-childbearing potential.

- sexually active males or females (of childbearing potential) unwilling to practice
contraception during the study

- history of other malignancy within the past 5 years, except cured basal cell
carcinoma of skin and cured carcinoma in-situ of uterine cervix

- clinical or other evidence of CNS metastases

- myocardial infarction within the last 3 months

- any medical condition that contraindicates potential surgery

- lack of physical integrity of the upper gastrointestinal tract, malabsorption
syndrome or inability to take oral medication

- any serious uncontrolled concomitant disease

- any of the following laboratory values:

1. absolute neutrophil count < 1.5 E+09/L

2. platelet count < 80000 E+09/L

3. AST or ALT higher than 2 X normal

- major surgery within 4 weeks prior to start of study treatment, or lack of complete
recovery from effects of major surgery

- patients with known or suspected hypersensitivity to one of the Gleevec components.