Ripretinib for the treatment of metastatic gastrointestinal stromal tumors harboring dual mutations in KIT exons 11+17: a case report

Background: Ripretinib has demonstrated clinical efficacy as a fourth-line therapeutic option for patients with advanced gastrointestinal stromal tumors (GISTs), especially when resistance to imatinib occurs through secondary KIT mutations. Dual mutations in KIT exons are common in highly drug-resistant GISTs, posing substantial clinical challenges. Case Description: A 46-year-old man was referred to Peking University Shenzhen Hospital following the discovery of a jejunal mass during a routine health check-up. After the surgery, a diagnosis of moderately malignant spindle cell GIST of the small intestine was pathologically confirmed, per National Institutes of Health (NIH) criteria. Adjuvant imatinib treatment was not initiated due to financial constraints. Postoperative surveillance revealed hepatic metastasis, leading to postoperative imatinib therapy. Progressive disease with increasing hepatic metastases prompted a second surgery. Genetic profiling identified the presence of dual mutations in KIT exons 11 and 17. Postoperative sunitinib therapy was initiated but failed to halt the metastasis. Following the third surgical procedure, genetic evaluation confirmed the persistence of the dual mutations, after which the patient was converted to postoperative regorafenib therapy. Nevertheless, abdominal metastases were detected upon reexaminations, prompting a modification of the treatment protocol to ripretinib 150 mg/day, which resulted in a reduction in metastatic lesion sizes. Before ripretinib treatment, the metastatic tumor measured 24 mm × 22 mm. During follow-up, contrast-enhanced computed tomography (CECT) scans revealed metastatic tumor sizes of 14 mm × 19 mm (May 2023), 12 mm × 14 mm (September 2023), and 11 mm × 8 mm (May 2024). Conclusions: Ripretinib may be an efficacious therapeutic option for early intervention of GIST patients harboring dual mutations in KIT exons 11 and 17.