M.T., a 59-year-old female patient with unresectable malignant gastric gastrointestinal stromal tumor (GIST) presents to discuss treatment options.
Relevant Medical History
Clinical Presentation/Laboratory Tests
- Diagnosed in 2015 when she experienced abdominal pain
- Tumor was KIT exon 9 mutation-positive
- She was initiated on imatinib 400 mg orally daily
- At 3 months after initiating treatment, CT scan showed widespread disease progression with metastases in the liver, peritoneum, and lungs despite medication compliance
Given short interval disease progression while receiving treatment with imatinib, M.T.’s clinician considered other options.
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For the primary treatment of GIST that is definitively unresectable, recurrent, or metastatic, the National Comprehensive Cancer Network recommends imatinib (category 1 recommendation). Upon generalized progression as assessed within 3 months of initiating therapy, imatinib can be dose-escalated as tolerated for patients with a performance status of 0 to 2, or treatment can be changed to sunitinib (category 1 recommendation). Regorafenib should be used only if disease is progressing despite prior imatinib and sunitinib therapy, followed by sorafenib, nilotinib, dasatinib (for patients with D842V mutation), or pazopanib. Clinicians should also consider participation in clinical trials.1,2
As different exon mutations may confer varying sensitivity to imatinib and sunitinib, clinicians should perform genetic molecular testing (for mutations in KIT or PDGFRA) to support the diagnosis of GIST. For example, tumors with KIT exon 11 mutations have the highest sensitivity to imatinib but are less likely to respond to second-line sunitinib.1
- National Comprehensive Cancer Network. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines): Soft Tissue Sarcoma. V 2.2016. Available at: https://www.nccn.org/professionals/physician_gls/pdf/sarcoma.pdf.
- Stivarga (regorafenib) [prescribing information]. Whippany, NJ: Bayer HealthCare Pharmaceuticals Inc. http://labeling.bayerhealthcare.com/html/products/pi/Stivarga_PI.pdf.