This is a 2 arms study concerning patients with primary GIST who followed an Imatinib adjuvant treatment for 3 years after surgery and who have a high risk of recurrence. In the first arm, patients will continue Imatinib treatment for 3 more years, allowing to determine if the continuation of this treatment is efficient for disease control, in terms of Disease Free Survival improvement. In the second arm, patients will discontinue the Imatinib treatment, as standard practice. This arm will allow to determine if the re-introduction of Imatinib at relapse is still an efficient treatment for the control of disease.
Name: Imatinib maintenance
Description: Time from the date of randomisation to the first documented relapse or death due to any cause. Patients with no event at the time of analysis will be censored at the date of the last adequate tumour assessment. The results will be analyzed according to the study arm and randomization strata to wich patients were assigned.
Measure: Disease Free Survival (DFS) Time: 6 years (i.e. at the the time of last patient last visit)Description: Time from the date of randomization until the date of death due to any cause and censored at the date of last contact for patients alive at last contact. The results will be analyzed according to the study arm and randomization strata to wich patients were assigned.
Measure: Overall Survival (OS) Time: 6 years (i.e. at the the time of last patient last visit)Description: Time from the date of randomization until the date of first relapse under Imatinib treatment (i.e first relapse in the "Imatinib maintenance arm" and relapse after reintroduction of Imatinib in the "Interruption of Imatinib arm"). The results will be analyzed according to the study arm and randomization strata to wich patients were assigned.
Measure: Time to Secondary Resistance (TSR) Time: 6 years (i.e. at the the time of last patient last visit)Description: Percentage of patients in Complete Response (CR) after reintroduction of Imatinib treatment for patients assigned to the interruption arm and who experience GIST recurrence. CR is assessed by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria
Measure: Percentage of patients in Complete Response (%CR) in interruption arm after reintroduction of Imatinib Time: 6 years (i.e. at the the time of last patient last visit)Description: The assessment of safety will be based mainly on the frequency of AE based on the Common Toxicity Criteria version 4 grade. AE will be coded according to the Medical Dictionary for Regulatory Activities (MedDRA). Descriptive statistics will be provided for characterizing and assessing patient tolerance to treatment. Patients with at least either one serious AE, or one grade 3-4, or one AE requiring the interruption of study treatment, will be described by study arm and compared using a Pearson's Chi2 test or a Fisher's exact test, if adequate. Patients will be analyzed according the duration of exposure to imatinib
Measure: Frequency of Adverse Events (AE) Time: 6 years (i.e. at the the time of last patient last visit)Description: QoL will be assessed using the European Organization for Research and Treatment of Cancer (EORTC) Quality of life Questionnaire (QLQ-C30). Descriptive statistics (e.g. means and medians) will be used to summarize the scored scales at it scheduled assessment time point of the questionnaire. The distribution of time to definitive health-related QoL deterioration by study arms will be estimated using the Kaplan-Meier method. The time to definitive deterioration is defined as the time from the date of randomization to the date of event, wich is defined as > 10 points decrease from baseline of QLQ-C30 global score (items 29 and 30) or death due to any cause. If patient has not had an event, time to QoL deterioration will be censored at the date of last adequate evaluation.
Measure: Patient's Quality of Life (QoL) Time: 6 years (i.e at the the time of last patient last visit)Allocation: Randomized
Parallel Assignment
There is one SNP
Exclusion Criteria: - Pregnant or breastfeeding women - Patient concurrently using other approved or investigational antineoplastic agents - Any contra-indication to imatinib treatment as per Glivec® SPC - Patient with GIST harboring the mutation D842V in PDGFRA - Major concurrent disease affecting cardiovascular system, liver, kidneys, haematopoietic system or else considered as clinically important by the investigator and that could be incompatible with patient's participation in this trial or would likely interfere with study procedures or results. --- D842V ---