Clinical Research of Drug Holiday Based on MRD Detection in GIST Patients at High Risk of Recurrence

Inclusion Criteria: * ① Age: ≥18 years and ≤75 years; * ② The primary lesion (and metastatic lesion) underwent R0 or R1 surgical resection, and patients were clinically diagnosed with high recurrence risk GIST combined with postoperative pathological results; * ③ The patient have received imatinib adjuvant therapy for 3 years after surgery, and no gross lesions were detected by imaging examination, and the possibility of drug withdrawal was considered based on the comprehensive judgment of the doctor in charge; * ④ The liquid biopsy for baseline ctDNA is negative; * ⑤ Primary Imatinib resistant mutations were not detected by genetic testing, such as SDH-deficient GIST, NF1-mutant GIST, BRAF-mutant GIST and GIST with NTRK3 rearrangement; * ⑥ PS score is 0-1 and expected survival time is more than 4 months; * ⑦ Patients are willing to stop drug use and observe, and patients and their families could understand the study protocol and voluntarily participate in this study, and signed informed consent. In the follow-up study, they could provide the clinical pathological data and imaging data needed for the study process, cooperate with the follow-up and collect the blood of the clinical efficacy evaluation, and agree to use the test data for the follow-up study and product development. Exclusion Criteria: * ① Fresh or paraffin tissue of the surgical tumor is not available; * ② Not receiving the assigned treatment or change therapy before disease progression; * ③ Unable to cooperate with follow-up with the study according to defined clinical period; * ④ Unable to take or provide defined imaging assessment examinations; * ⑤ Other conditions that investigators consider inappropriate for enrollment.