From the Guidelines
The primary treatment for metastatic Gastrointestinal Stromal Tumor (GIST) is imatinib at a standard dose of 400 mg daily, with the option to increase to 800 mg daily for patients with KIT exon 9 mutations, as recommended by the most recent guidelines 1.
Treatment Options
The treatment of metastatic GIST involves targeted therapy with tyrosine kinase inhibitors. The key treatment options include:
- Imatinib (Gleevec) as the first-line treatment at a standard dose of 400 mg daily
- Sunitinib (Sutent) as the second-line treatment at 50 mg daily for 4 weeks on, 2 weeks off
- Regorafenib (Stivarga) as the third-line therapy at 160 mg daily for 3 weeks on, 1 week off
- Avapritinib (Ayvakit) for patients with specific mutations like PDGFRA D842V
Treatment Approach
Treatment is typically continued indefinitely until disease progression or intolerable toxicity occurs. Regular monitoring with CT scans every 3-6 months is recommended to assess response.
Key Considerations
- Surgical resection of metastatic disease may be considered in selected patients with good response to tyrosine kinase inhibitors
- Side effects should be managed proactively, including edema, muscle cramps, diarrhea, and fatigue for imatinib; hypertension, hand-foot syndrome, and fatigue for sunitinib and regorafenib
- The choice of treatment should be individualized based on patient factors, including mutation status and prior treatment response, as per the latest clinical practice guidelines 1.
From the FDA Drug Label
- 2 Gastrointestinal Stromal Tumors STIVARGA is indicated for the treatment of patients with locally advanced, unresectable or metastatic gastrointestinal stromal tumor (GIST) who have been previously treated with imatinib mesylate and sunitinib malate.
The treatment option for metastatic Gastrointestinal Stromal Tumor (GIST) is regorafenib (STIVARGA), which is indicated for patients who have been previously treated with imatinib mesylate and sunitinib malate 2.
- Key points:
- Regorafenib is used for locally advanced, unresectable, or metastatic GIST.
- Patients should have been previously treated with imatinib mesylate and sunitinib malate.
- The recommended dose is 160 mg regorafenib orally once daily for the first 21 days of each 28-day cycle 2.
From the Research
Treatment Options for Metastatic GIST
- The standard first-line treatment for metastatic GIST is imatinib, a tyrosine kinase inhibitor (TKI) 3, 4, 5, 6
- High-dose imatinib (800 mg daily) may be beneficial for patients with advanced or metastatic GIST that progresses on the standard dose, particularly those with KIT exon 9 mutations 3
- Second-line and third-line treatment options include sunitinib and regorafenib, respectively, for patients who are resistant or intolerant to imatinib 4, 6
- Ripretinib, a switch-control tyrosine kinase inhibitor, has been approved for fourth-line treatment in metastatic GIST 4, 6
- Avapritinib, a TKI, has been approved for metastatic GIST harboring the imatinib-resistant PDGFRA exon 18 mutation 4, 6
Surgical Management
- Cytoreductive surgery may be considered for patients with metastatic GIST, particularly those who have responded to TKI therapy 4
- Surgical resection can be performed safely and effectively in patients with metastatic GIST, but it is not curative and should be individualized based on patient factors and disease characteristics 4
- Debulking or palliative surgery may be necessary for patients with complications such as hemorrhage, pain, or intestinal obstruction 4
Long-term Outcomes
- Imatinib therapy has been shown to have high clinical efficacy in terms of long-term survival in GIST patients, with 5-, 10-, 15-, and 20-year overall survival rates of 64.3%, 30.0%, 16.8%, and 12.2%, respectively 7
- However, patients undergoing imatinib therapy are at continuous risk of disease progression even after 10 years of treatment, highlighting the need for long-term follow-up and treatment 7