Efficiency of Imatinib Treatment Maintenance or Interruption After 3 Years of Adjuvant Treatment in Patients With Gastrointestinal Stromal Tumours (GIST)

Inclusion Criteria

• •Age ≥ 18 years at the day of consenting to the study
• •Patients must have histologically confirmed diagnosis of localized GIST with documented KIT (CD117) positivity (by polyclonal DAKO antibody staining)
• •Documented macroscopically complete surgical R0 or R1 resection of primary GIST lesion with no evidence of residual lesions or metastases on the baseline CT-scan or MRI performed no more than 4 weeks before randomization.
• •Risk of tumor recurrence ≥ 35% according to National Comprehensive Cancer Network Task Force on GIST (NCCN) risk classification (Demetri et al., 2010) (See Appendix 1)
• •Eastern Cooperative Oncology Group (ECOG) performance status 0, 1 or 2
• •Patients must be under imatinib treatment (at 300 or 400 mg/day) initiated immediately after resection and maintained for 3 years (i.e. 36 months ± 3 months at the time of randomization) with no more than 3 consecutive months or 6 months in total of interruption during these past 3 years.
• •Patients must have normal organ and bone marrow function at baseline as defined below:
• •* absolute neutrophil count (ANC) ≥ 1.5 G/L, platelet count ≥ 100 G/L, and haemoglobin of ≥ 9 g/dL).
• •* Serum total bilirubin ≤ 1.5 (upper limit of normal (ULN), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 3 x ULN (or 5 x ULN in case of hepatic metastases at time of reintroduction)
• •* Adequate renal function assessed by at least one of the following:
• •* 1\) Serum creatinine ≤ 1.5 x ULN or
• •* 2\) creatinine clearance estimate ≥ 50 mL/min (as calculated according to Cockcroft-Gault formula or MDRD formula for patients \> 65 years).
• •Recovered from prior anti-neoplasia treatment-related toxicity (persistent treatment-related toxicity \< Grade 2 as per Common Toxicity Criteria for Adverse Effects (CTCAE) v4 are accepted)
• •Women of childbearing potential are required to have a negative serum pregnancy test within 72 hours prior to randomization. A positive urine test must be confirmed by a serum pregnancy test
• •Patient must use effective contraception at least 4 weeks prior to study entry, during the study participation and for at least 30 days post-treatment (not applicable for women of non-childbearing potential)
• •Ability to understand and willingness for follow-up visits.
• •Covered by a medical insurance.
• •Signed and dated informed consent document indicating that the patient has been informed of all aspects of the trial prior to enrolment.