Your mutation matters in
getting the right treatment
for your GIST.
impact treatment outcomes.
mutation you have.
of your disease.
Your specific mutation matters in getting the right treatment for your type of GIST.
Mutations, or abnormal changes in genes, can cause cancer by making cells in the body grow and spread when they are not supposed to. In GIST, mutations lead tumors to develop along with the normal cells of the gastrointestinal tract.
BRAF, B-Raf proto-oncogene, serine/threonine kinase; KIT, KIT proto-oncogene receptor tyrosine kinase; KRAS, KRAS proto-oncogene, GTPase; NF1, neurofibromin 1; PDGFRA, platelet-derived growth factor receptor alpha; SDH, succinate dehydrogenase.
aSDH deficiency refers to a decrease in succinate dehydrogenase (SUX-sin-ate dee-high-DRAW-jen-ase), a protein. The decrease can develop from mutations in specific genes.
Reference: Florindez J, Trent J. Low frequency of mutation testing in the United States: an analysis of 3866 GIST patients. Am J Clin Oncol. Published online Jan 3, 2020. doi:10.1097/COC.0000000000000659
Mutational testing is the only way to confirm which mutation is causing your GIST.
Confirming your specific mutation through mutational testing is the best way to ensure that your treatment plan is right for your type of GIST.
How is mutational testing done?
A sample of your tumor tissue is tested to learn which mutations are driving your GIST. The tissue needed for the test might already be available if you have had surgery for GIST. Tumor tissue is stored for several years after surgery so that taking another sample usually should not be necessary.
Testing can be done in several ways.
- Sequencing (screening) for KIT and PDGFRA: This type of test focuses on identifying the most common GIST mutations in the KIT and PDGFRA genes. This is a common type of mutational testing in GIST.
- Next-generation sequencing, NGS: NGS is a type of broad test that checks for many different types of general cancer mutations, including those in KIT and PDGFRA. NGS may be more expensive and results may take longer, but it provides the most information. NGS is commonly used if no mutations are detected in KIT or PDGFRA.
- Taking a sample of circulating tumor DNA, also called a "liquid biopsy": Unlike the others, this type of test uses a blood sample. It can identify cancer mutations in DNA that “shed” from the tumor into the bloodstream by using next-generation sequencing. This type of test can provide a complete picture when GIST has several mutations (which can happen when patients have received several tyrosine kinase inhibitor [TKI] medicines to treat their cancer). The technology needs to be studied further before it is used routinely in GIST care.
What is immunohistochemistry, or IHC staining, for KIT?
This type of test helps your doctor determine whether the tissue removed (or resected) is GIST or something else. It may lead to a report that says your GIST tests positive for KIT, but it is not the same as mutational testing. It cannot confirm if you have a KIT mutation.
Ask your care team when you will get your results. They may recommend that you start a treatment before you receive them.
The test results will tell you about your mutation.
Think of the results like an address:
Example results of GIST mutational testing
| Gene | Exon | Alteration |
| KIT | exon 11 | V560D |
| PDGFRA | exon 18 | D842V |
Some test results may not include your exon, but results should always include information about your gene and alteration. The alteration listed in mutational test results can represent a change in the amino acid or DNA change. Ask your doctor to explain what this means for you.
 |
Without knowing the gene and alteration that are driving your GIST, you may be starting treatment with incomplete information. |
Expert guidelines recommend mutational testing to guide treatment in GIST.
Hear from GIST experts explaining why it's important for people with GIST to know which mutation they have.
Knowing the type of mutation you have will help your doctor find the right treatment for your GIST.
Testing as soon as possible is best. This improves your chances of avoiding treatments that don’t work and starting one that is most likely to help. The results of mutational testing may give your doctor answers to these questions:
It’s important to consult with an expert on GIST to understand all treatment options for your mutation.
GIST is a rare and complex type of cancer. Your treatment should be the right one for the exact mutation causing it. The first treatment (called first-line treatment) for most patients who have advanced GIST is the drug imatinib.
- The normal indicated dose of imatinib is 400 milligrams per day.
References: Bannon AE, Klug LR, Corless CL, Heinrich MC. Using molecular diagnostic testing to personalize the treatment of patients with gastrointestinal stromal tumors. Expert Rev Mol Diagn. 2017;17(5):445-457. Gleevec [package insert]. East Hanover, NJ: Novartis Pharmaceuticals Corporation; 2018.
- Patients with certain mutations may need a higher dose of imatinib or a different medicine altogether.
- Some mutations can prevent imatinib from working at all.
For up to 30% of GIST mutations, imatinib may not work, or a higher dose may be recommended.
Reference: Bannon AE, Klug LR, Corless CL, Heinrich MC. Using molecular diagnostic testing to personalize the treatment of patients with gastrointestinal stromal tumors. Expert Rev Mol Diagn. 2017;17(5):445-457.
Talk to your doctor about your treatment options.
To find a GIST specialist, click here.
Suggested resources for patients living with GIST
Blueprint Medicines™ and patient advocacy organizations are committed to increasing mutational testing in GIST. Find more information about GIST from experts, as well as support for patients and caregivers, at the following websites:
Blueprint Medicines is not affiliated with these organizations, does not endorse any particular service or group, and is not responsible for the content on their websites or any services or materials they may provide.
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