Inclusion Criteria:

- Patients >= 18 years of age

- Histologically documented diagnosis of GIST which is malignant as well as
unresectable (=not amenable to surgery with curative intent) and/or metastatic and
therefore incurable Immunohistochemical documentation of c-kit (CD117) expression by
tumor

- At least one measurable site of disease (as defined by Southwestern Oncology Group
Solid Tumor Response Criteria) which has not been previously embolised or irradiated

- Performance status 0,1, 2 or 3 (ECOG)

- Adequate end organ function, defined as the following: total bilirubin < 1.5 x ULN,
SGOT and SGPT < 2.5 x UNL (or < 5 x ULN if hepatic metastases are present),
creatinine < 1.5 x ULN, ANC > 1.5 x 109/L, platelets > 100 x 109/L

- Female patients of child-bearing potential must have negative pregnancy test within 7
days before initiation of study drug dosing. Post menopausal women must be
amenorrheic for at least 12 months to be considered of non-childbearing potential.
Male and female patients of reproductive potential must agree to employ an effective
barrier method of birth control throughout the study and for up to 3 months following
discontinuation of study drug

- Life expectancy of at least 6 months

- Written, voluntary, informed consent

- Patients who were previously treated with chemotherapy will be eligible for this
study

- Patient who are at least 5 years free of melanoma will be eligible for this study

Exclusion Criteria:

- Patient has received any other investigational agents within 28 days of first day of
study drug dosing

- Patient is < 5 years free of another primary malignancy except: if the other primary
malignancy is not currently clinically significant nor requiring active intervention
and CECOGs' approval is obtained, or if other primary malignancy is a basal cell skin
cancer or a cervical carcinoma in situ. Existence of any other malignant disease is
not allowed

- Patient with Grade III/IV cardiac problems as defined by the New York Heart
Association Criteria. (i.e., congestive heart failure, myocardial infarction within 6
months of study)

- Female patients who are pregnant or breast-feeding.

- Patient has a severe and/or uncontrolled medical disease (i.e., uncontrolled
diabetes, chronic renal disease, or active uncontrolled infection)

- Patient has a known brain metastasis

- Patient has an acute or known chronic liver disease (i.e., chronic active hepatitis,
cirrhosis)

- Patient has a known diagnosis of human immunodeficiency virus (HIV) infection

- Patient received chemotherapy within 4 weeks (6 weeks for nitrosoureas or
mitomycin-C) prior to study entry

- Patient previously received radiotherapy to >= 25 % of the bone marrow

- Patient had a major surgery within 2 weeks prior to study entry

- Patient with any significant history of non-compliance to medical regimens or with
inability to grant reliable informed consent

- Therapeutic anticoagulation with warfarin (e.g. Coumadin® or Coumadine®)