Preoperative and Postoperative Imatinib Mesylate Study in Patients With c-Kit Positive GIST

Inclusion Criteria:

1. Signed informed consent.
2. Patients must have a histologically proven diagnosis of primary, locally advanced and/or metastatic GIST for which complete or partial resection is planned by a MDACC sarcoma surgeon.
3. Patients must have immunohistochemical documentation of kit expression in the tumor using the DAKO A4502 or other acceptable antibody.
4. Patients must have a least one lesion greater than 1 cm that can be accurately measured in one dimension by plain radiograph, CT or magnetic resonance imaging (MRI).
5. Patients must have normal organ and marrow function (White blood count-WBC greater than or equal to 3,000/ul, Absolute neutrophil count (ANC) greater than or equal to 1500/ul, platelets greater than or equal to 100,00/ul, total bilirubin less than or equal to 1.5 \* Upper Limits of Normal (ULN), aspartate aminotransferase (AST or SGOT) or alanine aminotransferase (ALT or SGPT) less than or equal to 2.5 \* ULN, serum creatinine less than or equal to 1.5 \* ULN).
6. Patients must have a serum glucose \< 200 mg/dl prior to PET scan. Patients must be able to lie flat and still for the PET scan.
7. Patients may not have any uncontrolled medical or psychiatric conditions that would make the patient unable to tolerate therapy. Patients with uncontrolled medical conditions or psychiatric conditions may have informed consent granted by a legal guardian or surrogate decision maker.
8. Patients may not have any prior malignancy in the past 5 years other than non-melanoma skin cancer, cervical cancer in situ, or any other malignancy that is not currently clinically significant.
9. Zubrod performance status of 0 - 3.
10. May not have metastases outside of the peritoneal cavity.
11. If patients have any signs or symptoms of metastases, the appropriate workup should occur prior to enrollment (eg, CT of the head for a patient with central nervous system (CNS) symptoms).
12. Patients may not have had chemotherapy, radiotherapy, biological therapy or any investigational drugs 3 weeks prior to the study.
13. Women should have a negative pregnancy test within 7 days of study opening.
14. Patients must agree to use an effective contraceptive method.

Exclusion Criteria:

1. Prior treatment using Gleevec.
2. Patients with Class III or Class IV New York Heart Association congestive heart failure.
3. Pregnant or nursing women.
4. Patients taking therapeutic doses of Coumadin for anticoagulation. Coumadin may be taken but dose should be less than or equal to 1 mg po per day. Patients MAY take a low molecular weight heparin.