A Study of Regorafenib Combined With Envafolimab for Metastatic Gastrointestinal Stromal Tumors With Kit Gene Exon 17 Mutation That Failed Standard Treatment

"-Regorafenib: Specification: 40 mg/tablet Dosage: 120 mg, taken orally once daily for 3 weeks, followed by 1 week off, until disease progression or intolerable toxicity occurs.~* Envafolimab:~Specification: 200 mg/vial Dosage: 200 mg, administered via subcutaneous injection once every 2 weeks, until disease progression or intolerable toxicity occurs."

The governing principle for physician decision-making in the control group was selection based on prior medication tolerability, genotype, etc.: a. Continued maintenance therapy with the originally effective TKI at the same dose: The patient achieved at least stable disease (SD) or partial response (PR) during prior treatment, with progression-free survival (PFS) exceeding 6 months, and the adverse reactions were tolerable. b. Combination therapy with two TKIs: Different drugs were selected for maintenance based on distinct actionable mutations identified in the patient's tissue or peripheral blood genetic testing, OR a combination of drugs previously effective and well-tolerated was used, OR the combination therapy was chosen by referencing past tolerability.