GIST
Gastrointestinal stromal tumour — KIT/PDGFRA driven
DefinitionClick to collapse
Gastrointestinal stromal tumors (GIST) are the most common soft tissue sarcomas of the gastrointestinal (GI) tract, primarily arising from interstitial cells of Cajal or their precursors, which are pacemaker cells involved in GI motility [1,6]. Embryologically, these cells originate from the mesenchyme. Anatomically, GIST can develop anywhere along the GI tract, with the stomach being the most frequent site (approximately 60% of cases), followed by the small intestine (30%), duodenum (4%–5%), rectum (4%), esophagus (<1%), and colon or appendix (1%–2%) [6]. Rarely, GIST can occur in extraintestinal sites such as the omentum or peritoneum. Diagnosis relies on morphologic examination of tumor tissue, supported by immunohistochemical staining for CD117 (KIT protein, expressed in 95% of GIST), DOG1, and CD34 (expressed in about 70% of cases) [6,7]. Molecular genetic testing for mutations in the KIT or PDGFRA genes is essential for confirming diagnosis and guiding therapy, as these mutations define most GIST [9,10,11]. Clinical presentation varies; patients may experience abdominal discomfort, early satiety, GI bleeding due to ulceration, or an acute abdomen from tumor rupture, obstruction, or peritonitis [7]. GIST tends to be fragile, with a pseudocapsule, and metastasis most commonly occurs to the liver and peritoneum, while lymph node involvement is rare except in specific subtypes [6].
EpidemiologyClick to collapse
The annual incidence of gastrointestinal stromal tumors (GIST) in the United States is estimated to be between 0.68 and 0.78 per 100,000 population, based on population-based studies [2,3,4,5]. Mortality data are less consistently reported, but survival rates vary by stage and risk stratification; for example, the 5-year survival rate for localized GIST is high after resection, but drops significantly for metastatic disease [49,50]. Trends suggest a potential increase in incidence over time, possibly due to improved diagnostic methods and awareness, though this is not explicitly detailed in the source [2]. Demographically, GIST typically affects adults, with a median age at diagnosis around 60–65 years; it is slightly more common in males than females in some series, but the source does not provide specific sex ratios [6]. Racial and ethnic disparities are not mentioned in the provided text; however, incidence may vary geographically, but no specific SEER or GLOBOCAN numbers are given beyond the U.S. estimates. Primary site distribution is well-documented: stomach accounts for 60% of cases, small intestine for 30%, duodenum for 4%–5%, rectum for 4%, esophagus for <1%, and colon or appendix for 1%–2%, with rare extraintestinal occurrences [6]. These sites have different prognostic implications, as gastric GIST tend to be more indolent compared to small intestinal or rectal GIST, which are more aggressive [6,24,25].
SubtypesClick to collapse
KIT-mutant GIST
The most common subtype, characterized by activating mutations in the KIT gene encoding a receptor tyrosine kinase. Mutations typically occur in exon 11 (juxtamembrane domain, most frequent) or exon 9 (extracellular domain), with rarer mutations in exons 13 or 17 [13,14]. KIT mutations lead to constitutive kinase activation, driving tumor growth.
PDGFRA-mutant GIST
Characterized by mutations in the PDGFRA gene, another receptor tyrosine kinase. Mutations predominantly affect exon 18 (tyrosine kinase domain), such as D842V, with rarer mutations in exon 12 (juxtamembrane domain) or exon 14 [15]. These mutations result in autonomous signaling.
SDH-deficient GIST
Also known as wild-type GIST lacking KIT or PDGFRA mutations, these tumors have functional inactivation of the succinate dehydrogenase (SDH) complex due to mutations in SDH subunits (e.g., SDHB, SDHC, SDHD) or epigenetic silencing [16,18,19]. Loss of SDHB expression by immunohistochemistry is a hallmark.
NF1-associated GIST
Arise in patients with neurofibromatosis type 1 (NF1) syndrome, caused by inactivating mutations in the NF1 gene, leading to loss of neurofibromin and activation of RAS signaling [101].
BRAF-mutant GIST
Characterized by activating mutations in the BRAF gene, most commonly V600E, which activates the MAPK pathway.
NTRK-fusion positive GIST
Defined by gene fusions involving NTRK genes (e.g., NTRK1, NTRK2, NTRK3), leading to TRK kinase activation.
Histologic subtypes
Based on morphology, GIST can be classified as spindle cell type (most common, with elongated cells), epithelioid type (round to polygonal cells), or mixed type. Spindle cell GIST is typical for KIT-mutant tumors, while epithelioid may be more common in PDGFRA-mutant or SDH-deficient tumors [6,12].
Molecular PathogenesisClick to collapse
The molecular pathogenesis of GIST is driven by constitutive activation of tyrosine kinase signaling pathways, primarily through oncogenic mutations in KIT or PDGFRA receptor tyrosine kinase genes [1,10]. Approximately 80% of GIST harbor mutations in the KIT gene, which encodes a transmembrane receptor involved in cell growth and survival [9,10]. Most KIT mutations occur in exon 11 (juxtamembrane domain), leading to ligand-independent activation; mutations in exon 9 (extracellular domain) are less common and often associated with intestinal GIST [13]. Rarely, mutations in exons 13 or 17 (tyrosine kinase domain) occur [14]. About 5%–10% of GIST have mutations in the PDGFRA gene, a related receptor tyrosine kinase, with the majority affecting exon 18 (tyrosine kinase domain), such as the D842V mutation [11,15]. These mutations result in gain-of-function, driving tumor proliferation via downstream pathways like RAS/MAPK and PI3K/AKT. In 10%–15% of GIST, neither KIT nor PDGFRA mutations are detectable (wild-type GIST); the majority of these have functional inactivation of the succinate dehydrogenase (SDH) complex due to mutations in SDH subunits (SDHA, SDHB, SDHC, SDHD) or epigenetic silencing, leading to metabolic reprogramming and tumorigenesis [16,18,19]. SDH-deficient GIST often arise in younger patients and have a distinct clinical behavior [83]. Other rare genomic events include BRAF V600E mutations (activating the MAPK pathway), inactivating NF1 mutations (affecting RAS regulation), and gene fusions involving NTRK or FGFR, which can serve as alternative drivers [21,93,101]. Chromosomal abnormalities, such as deletions of chromosome 14q and 22q, are frequently observed and may contribute to loss of tumor suppressor genes [7]. These molecular alterations dictate response to targeted therapies, such as tyrosine kinase inhibitors (TKIs), and are essential for risk stratification and treatment planning [GIST-B].
Risk FactorsClick to collapse
Neurofibromatosis type 1 (NF1) syndrome
Germline mutations in the NF1 gene predispose to the development of GIST, often multifocal and arising in the small intestine. NF1-associated GIST may have a more indolent course but require genetic counseling and testing [101,102].
Carney-Stratakis syndrome
An autosomal dominant disorder caused by germline mutations in SDH subunit genes (e.g., SDHB, SDHC, SDHD), leading to SDH-deficient GIST and a predisposition to paragangliomas [16,18].
Familial GIST syndromes
Rare familial cases with germline KIT or PDGFRA mutations, often presenting with multiple GIST and other features like mastocytosis [GIST-B].
Sporadic mutations
Most GIST occur sporadically due to somatic mutations in KIT or PDGFRA genes, not inherited. Risk factors for these mutations are not well-defined, and environmental factors are not clearly identified in the source.
SDH deficiency
Loss of SDH function, whether from mutations or epigenetic silencing, is a key risk factor for a subset of GIST, particularly in younger individuals [16,19].
Clinical FeaturesClick to collapse
Typical Presentation
Gastrointestinal stromal tumors (GIST) are the most common soft tissue sarcoma of the gastrointestinal (GI) tract. Patients with a suspected GIST may present with a variety of symptoms, which may include early satiety, abdominal discomfort due to pain or swelling, intraperitoneal hemorrhage, GI bleeding, or fatigue related to anemia. Some patients may present with an acute abdomen, which requires immediate medical attention [MS-2]. GIST can arise anywhere along the GI tract, but stomach (60%) and small intestine (30%) are the most common primary sites. Duodenum (4%–5%) and rectum (4%) are less common, and only a small number of cases have been reported in the esophagus (<1%) and colon and appendix (1%–2%) [6].
Symptoms
Early satiety
May occur due to mass effect, especially with gastric GIST.
Abdominal discomfort/pain
Can be due to tumor size, local growth, or swelling.
GI bleeding
May present as melena or hematemesis; can be overt or occult leading to anemia.
Intraperitoneal hemorrhage
Acute event, often due to tumor rupture.
Fatigue
Often related to chronic blood loss and subsequent anemia.
Acute abdomen
Resulting from tumor rupture, GI obstruction, or peritonitis-like pain.
Signs
Palpable abdominal mass
May be discovered on physical examination, especially with larger tumors.
Red FlagsClick to collapse
Acute abdomen due to tumor rupture, GI obstruction, or peritonitis-like pain requiring immediate medical attention [MS-2].
Significant GI bleeding (hematemesis, melena) [MS-2].
Evidence of peritoneal spread or ascites on imaging.
Rapidly enlarging abdominal mass.
Unexplained iron-deficiency anemia.
InvestigationsClick to collapse
Diagnostic
Endoscopic ultrasound (EUS) with fine-needle aspiration biopsy (EUS-FNAB) or core needle biopsy (EUS-CNB)
EUS-FNAB is favored over percutaneous biopsy for primary lesions due to lower risk of peritoneal seeding. Biopsy is necessary to confirm diagnosis before preoperative therapy [GIST-A, MS-2].
CT abdomen/pelvis with contrast
Primary imaging modality to characterize abdominal mass, evaluate extent, and stage disease. Performed for workup, response assessment, and surveillance [GIST-F, MS-4].
MRI abdomen/pelvis with and without contrast
Alternative or adjunct to CT, especially if contrast allergy or for better soft tissue definition [GIST-F].
FDG-PET/CT
Can be used to assess early response to TKI therapy (after 2–4 weeks), clarify ambiguous CT/MRI findings, or evaluate complex metastatic disease before surgery. Should not substitute for diagnostic CT [GIST-F, MS-4].
Upper/lower endoscopy
Direct visualization and potential biopsy of GI lesions if not previously done [GIST-1].
Staging
CT chest
Recommended at baseline for unresectable or metastatic disease to evaluate for pulmonary metastases [GIST-1, GIST-F].
Chest X-ray
Alternative for baseline chest imaging [GIST-F].
Biomarkers
KIT (CD117) immunohistochemistry (IHC)
Standard diagnostic marker; expressed in ~95% of GIST [MS-2, GIST-A].
DOG1 IHC
Useful for diagnosis, especially in KIT-negative GIST or difficult cases [MS-3, GIST-A].
SDHB IHC
To detect SDH-deficient GIST (lack of SDHB expression) in KIT/PDGFRA wild-type tumors [GIST-B, MS-3].
Molecular testing for KIT and PDGFRA mutations
Predicts response to TKIs. Required before initiating preoperative or systemic TKI therapy [GIST-B, MS-9].
Next-generation sequencing (NGS)
To identify alternative driver mutations (e.g., BRAF, NF1, NTRK, FGFR fusions) in tumors lacking KIT/PDGFRA mutations or for comprehensive profiling [GIST-B].
StagingClick to collapse
American Joint Committee on Cancer (AJCC) Staging System, 8th Edition (2017) [ST-1].
T Categories
| Stage | Description |
|---|---|
| TX | Primary tumor cannot be assessed. |
| T0 | No evidence of primary tumor. |
| T1 | Tumor 2 cm or less in greatest dimension. |
| T2 | Tumor more than 2 cm but not more than 5 cm in greatest dimension. |
| T3 | Tumor more than 5 cm but not more than 10 cm in greatest dimension. |
| T4 | Tumor more than 10 cm in greatest dimension. |
N Categories
| Stage | Description |
|---|---|
| N0 | No regional lymph node metastasis or unknown lymph node status. |
| N1 | Regional lymph node metastasis. |
M Categories
| Stage | Description |
|---|---|
| M0 | No distant metastasis. |
| M1 | Distant metastasis. |
Stage Groupings
| Group | Criteria | Clinical Meaning | Five Yr Survival | Treatment Intent |
|---|---|---|---|---|
| Gastric GIST | Stage IA: T1 or T2, N0, M0, Low mitotic rate. Stage IB: T3, N0, M0, Low mitotic rate. Stage II: T1 or T2, N0, M0, High mitotic rate; OR T4, N0, M0, Low mitotic rate. Stage IIIA: T3, N0, M0, High mitotic rate. Stage IIIB: T4, N0, M0, High mitotic rate. Stage IV: Any T, N1, M0, Any mitotic rate; OR Any T, Any N, M1, Any mitotic rate. | Prognostic groups based on tumor size, nodal status, metastasis, and mitotic rate (Low: ≤5 mitoses per 50 HPF; High: >5 mitoses per 50 HPF). | None | Staging guides prognosis and treatment decisions (e.g., adjuvant therapy for high-risk). |
| Small Intestinal GIST (also used for esophagus, colorectal, mesenteric, peritoneal) | Stage I: T1 or T2, N0, M0, Low mitotic rate. Stage II: T3, N0, M0, Low mitotic rate. Stage IIIA: T1 or T4, N0, M0, High mitotic rate; OR T4, N0, M0, Low mitotic rate. Stage IIIB: T2, T3, or T4, N0, M0, High mitotic rate. Stage IV: Any T, N1, M0, Any mitotic rate; OR Any T, Any N, M1, Any mitotic rate. | Similar prognostic grouping but with different stage assignments reflecting more aggressive biology of non-gastric GIST. | None | Staging guides prognosis and treatment decisions. |
Staging Pearls
- Gastric GIST are generally more indolent than small intestinal GIST [GIST-A, MS-3].
- Risk stratification for recurrence after resection also incorporates tumor size, mitotic rate, and anatomic location (gastric vs. non-gastric) [GIST-A].
- Tumor rupture during surgery or preoperatively is associated with a much higher risk of recurrence and should be considered metastatic disease [GIST-3].
- The mitotic rate should be measured in the most proliferative area of the tumor and reported per 50 high-power fields (HPFs), equivalent to 5 mm² of tissue [GIST-A].
- SDH-deficient GIST are more unpredictable in behavior and are not well stratified by standard risk tables [GIST-A].
SurveillanceClick to collapse
Clinical Follow Up Schedule
- H&P every 3–6 months for the first 5 years post-resection, then annually [GIST-3].
- For high-risk disease, more frequent imaging may be required [GIST-F].
- For unresectable or metastatic disease on TKI therapy, H&P and imaging every 3–6 months to assess response [GIST-4].
Imaging Strategy
- CT abdomen/pelvis with contrast and/or MRI abdomen/pelvis with and without contrast every 3–6 months for 5 years, then annually [GIST-F].
- FDG-PET/CT may be used to clarify ambiguous CT/MRI findings or to assess response to TKI therapy; it can indicate TKI efficacy after 2–4 weeks [GIST-F, MS-4].
- Chest imaging (x-ray or CT) should be considered for unresectable or metastatic disease [GIST-F].
- For very small gastric GIST <2 cm, periodic endoscopic or radiographic surveillance may be considered [GIST-1].
Laboratory Monitoring
- Not explicitly specified in the guideline, but for patients on sunitinib, monitor TSH every 3–6 months [68].
- Liver function tests for imatinib toxicity, especially in the first few months [59].
- Complete blood counts periodically for hematologic toxicities, particularly with sunitinib or regorafenib.
- Serum chemistry panels to monitor electrolytes and renal function.
Supportive Follow Up
- Monitoring for TKI side effects and management as per toxicity guidelines, with dose modifications as needed.
- Psychosocial support and symptom management to enhance quality of life.
- Referral to survivorship programs for long-term care and monitoring of late effects.
ComplicationsClick to collapse
Disease-Related
| Complication | Management |
|---|---|
| Metastatic disease | Systemic therapy with TKIs; surgery or interventional procedures for limited disease [GIST-4, GIST-5]. Liver and peritoneal metastases are most common; lymph node metastases are rare except in SDH-deficient GIST [MS-2]. |
| Tumor rupture or hemorrhage | Emergency surgery; considered as metastatic disease due to high recurrence risk [GIST-3, GIST-C]. Tumor rupture is a poor prognostic factor [v,52]. |
| GI obstruction or perforation | Surgical intervention [GIST-C]. May present as acute abdomen requiring immediate attention [MS-2]. |
Supportive CareClick to collapse
Supportive care in GIST is integral to maintaining quality of life during long-term TKI therapy. It involves proactive monitoring and management of treatment-related toxicities, nutritional support, and psychosocial care. A multidisciplinary team approach is recommended [GIST-1].
Patients with GIST, especially those with GI involvement, may experience weight loss, anorexia, or malnutrition. Nutritional assessment and dietetic support are recommended, with enteral or parenteral nutrition if needed to maintain adequate intake and prevent cachexia.
Nausea and vomiting are common with imatinib and sunitinib. Antiemetics such as ondansetron or prochlorperazine may be used as needed, based on the emetogenic potential of the TKI. Prophylactic antiemetics are not standard but can be considered for patients with severe symptoms.
Granulocyte colony-stimulating factor (GCSF) is not routinely recommended but may be considered for severe neutropenia, particularly with sunitinib or combination therapies. Close monitoring of complete blood counts is advised.
Venous thromboembolism prophylaxis is not specifically addressed in the guideline; standard cancer care guidelines should be followed for high-risk patients, such as those with immobilization or other risk factors.
Pain from tumor bulk, bone metastases, or treatment-related effects should be managed with analgesics, including opioids if necessary. Palliative radiotherapy is an option for symptomatic lesions [GIST-5]. A multimodal approach incorporating pharmacologic and non-pharmacologic methods is recommended.
The chronic nature of GIST and long-term TKI therapy can impact mental health. Referral to counseling, support groups, and palliative care services is encouraged to address anxiety, depression, and quality of life concerns.
Oral health is important during TKI therapy; patients should maintain good dental hygiene and report any oral ulcers or mucositis. Dental evaluations prior to starting therapy may be beneficial to prevent complications.
PrognosisClick to collapse
Gastrointestinal stromal tumors (GIST) have a variable prognosis influenced by tumor size, mitotic rate, anatomic site, and molecular profile. The annual incidence in the United States is estimated between 0.68 and 0.78 per 100,000 [2-5]. GIST can arise anywhere in the gastrointestinal tract, with the stomach (60%) and small intestine (30%) being the most common sites [6]. Approximately 80% of GIST harbor KIT mutations and 5%-10% have PDGFRA mutations, which are targetable by tyrosine kinase inhibitors (TKIs), significantly improving outcomes [1]. With surgery and adjuvant therapy, many patients achieve long-term disease control, but recurrence remains a risk, especially in high-risk disease [53,56]. The natural history has been transformed by imatinib, which induces objective responses in over 50% of patients with advanced disease [38,43].
By Stage
| Stage | Five Yr Survival | Context |
|---|---|---|
| Localized resectable GIST | Approximately 50% after complete resection without adjuvant therapy [49-51]. With adjuvant imatinib, recurrence-free survival is significantly improved; in the ACOSOG Z9001 trial, the hazard ratio (HR) for recurrence was 0.6 (95% CI, 0.43–0.75; P < .001) [53,54]. | Risk stratification using tumor size, mitotic rate, and site predicts recurrence. For gastric GIST, metastasis rates are 0% for tumors ≤2 cm, 1.9% for 2-5 cm with low mitoses, and up to 86% for >10 cm with high mitoses [24]. For non-gastric GIST, rates are higher: 50-54% for ≤2 cm with high mitoses and 71-90% for >10 cm with high mitoses [25]. |
| Unresectable, recurrent, or metastatic GIST | Long-term survival is limited; in the B2222 study, the estimated 9-year overall survival (OS) was 35% for all patients [43]. With first-line imatinib, median OS is significantly improved compared to historical controls. | Mutational status impacts prognosis: KIT exon 11 mutations associate with better response to imatinib than exon 9 mutations [70,73,74]. PDGFRA D842V mutations confer resistance to imatinib but respond to avapritinib [79,81]. SDH-deficient GIST are more unpredictable and often resistant to imatinib [83,84]. |
Prognostic Factors
- Tumor size and mitotic rate are primary pathologic features for risk stratification [24,25].
- Anatomic location: gastric GIST are indolent, especially if ≤2 cm; small intestinal GIST are more aggressive; rectal GIST are very aggressive [6,139].
- Mutation type: KIT exon 9 mutations predict lower response to imatinib 400 mg daily but benefit from higher doses [73,76]. PDGFRA D842V mutations are imatinib-insensitive [11,15].
- Response to TKI therapy: Patients with objective response or stable disease have better outcomes [38,43].
- Completeness of resection and tumor rupture: R0 resection is the goal; tumor rupture significantly increases recurrence risk [v,52].
- Sex: Female sex may associate with better PFS and OS in some studies [27].
- Genotype: KIT exon 11 deletions and non-gastric site are associated with poorer disease-free survival [26].
Follow UpClick to collapse
Post Curative Treatment
After complete resection without neoadjuvant therapy, history and physical (H&P) and imaging (CT abdomen/pelvis with contrast or MRI) are recommended every 3–6 months for 5 years, then annually. After 10 years, surveillance should be individualized [GIST-3, GIST-F]. For low-risk tumors, less frequent surveillance may be acceptable [GIST-F].
Surveillance Rationale
Surveillance aims to detect recurrence early, as treatment with TKIs is effective for recurrent or metastatic disease. Recurrence patterns indicate that most recurrences occur within the first 5 years, but late recurrences are possible, necessitating long-term monitoring.
Late Effects Screening
- Monitor for cardiac toxicity with imatinib and sunitinib: echocardiography or left ventricular ejection fraction (LVEF) assessment if symptoms arise [60,67].
- Screen for hypothyroidism with sunitinib every 3–6 months via thyroid-stimulating hormone (TSH) testing [68].
- Assess for other TKI-related effects such as skin changes, hypertension, and fatigue during follow-up visits.
- Evaluate for bone health in patients on long-term TKI therapy, as some may be at risk for osteoporosis.
Recurrence Patterns
Median time to recurrence after resection of high-risk GIST is about 2 years [49-51]. Recurrence can be locoregional or metastatic, commonly to the liver and peritoneum [MS-2]. Risk of recurrence is influenced by tumor size, mitotic rate, site, and mutation status [6,24,25].
Key TrialsClick to collapse
| Acronym | Full Name | Year | N | Intervention | Comparator | Population | Primary Endpoint | Key Result | Secondary Outcomes | Practice Change | Journal |
|---|---|---|---|---|---|---|---|---|---|---|---|
| B2222 | Phase II study of imatinib in advanced GIST | 2002 | 147 | Imatinib 400 mg or 600 mg daily | None | Patients with metastatic or unresectable KIT-positive GIST | Response rate, time to progression | Objective response in >50% of patients; estimated 9-year OS 35% [43]. | Long-term disease control; low tumor bulk at baseline predicted longer TTP and improved OS. | Established imatinib as standard therapy for advanced GIST. | New England Journal of Medicine |
| EORTC 62005 | Randomized trial of imatinib at two dose levels in advanced GIST | 2004 | 946 | Imatinib 400 mg daily vs 800 mg daily | None | Unresectable or metastatic GIST | Progression-free survival | No significant difference in PFS or OS at 10.9 years; HR for PFS 0.91 (95% CI, 0.79–1.04; P = .18); OS HR 0.93 (95% CI, 0.80–1.07; P = .31) [44]. | Response rates similar; higher dose associated with more side effects. | Standard dose imatinib 400 mg daily remains first-line. | Lancet |
| S0033/CALGB 150105 | Phase III randomized intergroup trial of imatinib at two dose levels | 2008 | 746 | Imatinib 400 mg daily vs 800 mg daily | None | Unresectable or metastatic GIST | Overall survival | No statistical difference in PFS or OS; median OS 55 vs 51 months [42]. | Response rates 40% vs 42%. | Confirmed standard dose of imatinib. | Journal of Clinical Oncology |
| ACOSOG Z9001 | Adjuvant imatinib for resected primary GIST | 2009 | 645 | Imatinib 400 mg daily for 1 year vs placebo | Placebo | Patients with primary localized GIST ≥3 cm after complete resection | Recurrence-free survival | Significant improvement in RFS; HR 0.6 (95% CI, 0.43–0.75; P < .001); OS not significantly different [53,54]. | Benefit in intermediate and high-risk tumors. | Established adjuvant imatinib for resected GIST. | Lancet |
| SSG XVIII/AIO | Randomized trial of adjuvant imatinib for 1 vs 3 years | 2012 | 400 | Imatinib for 1 year vs 3 years | None | High-risk resected GIST | Recurrence-free survival | Longer duration improved RFS; 5-year RFS 71.1% vs 52.3% (P < .001); 5-year OS 91.9% vs 85.3% (P = .036) [56,57]. | OS benefit with longer therapy. | Extended adjuvant therapy for high-risk GIST. | JAMA |
| GRID | Phase III trial of regorafenib in GIST after imatinib and sunitinib | 2013 | 199 | Regorafenib vs placebo | Placebo | Metastatic or unresectable GIST progressing on imatinib and sunitinib | Progression-free survival | Median PFS 4.8 vs 0.9 months (P < .0001); DCR 53% vs 9% [116]. | HR for OS 0.77 with 85% crossover to regorafenib. | Regorafenib as third-line therapy. | Lancet |
| INVICTUS | Phase III trial of ripretinib in advanced GIST | 2020 | 129 | Ripretinib 150 mg daily vs placebo | Placebo | Advanced GIST after imatinib, sunitinib, and regorafenib | Progression-free survival | Median PFS 6.3 vs 1.0 months (P < .0001) [118]. | Dose escalation to 150 mg BID upon progression showed median OS 18.4 months [119]. | Ripretinib as fourth-line therapy. | Lancet Oncology |
| NAVIGATOR | Phase I trial of avapritinib in PDGFRA D842V GIST | 2020 | 56 | Avapritinib | None | Unresectable or metastatic GIST with PDGFRA D842V mutation | Objective response rate | ORR 91%; median duration of response 27.6 months [81,82]. | Long-term efficacy and safety. | Avapritinib approved for PDGFRA D842V GIST. | Lancet Oncology |
Clinical PearlsClick to collapse
- Pearl 1: GIST are the most common sarcomas of the GI tract, driven by KIT or PDGFRA mutations [1,2].
- Pearl 2: Risk stratification for localized GIST is based on tumor size, mitotic rate, and anatomic site, using guidelines from Miettinen et al. [6,24,25].
- Pearl 3: Mutation testing is essential to guide therapy: imatinib for KIT/PDGFRA mutations, avapritinib for PDGFRA D842V, and specific therapies for NTRK fusions, BRAF mutations, etc. [GIST-B].
- Pearl 4: Surgery is the primary treatment for localized GIST, aiming for complete resection without tumor rupture. Lymphadenectomy is usually not required [GIST-C].
- Pearl 5: Adjuvant imatinib is recommended for intermediate- or high-risk resected GIST for at least 3 years, with data supporting 6 years for high-risk based on disease-free survival benefit [53,56,57].
- Pearl 6: For advanced GIST, imatinib is first-line; sunitinib second-line; regorafenib third-line; ripretinib fourth-line, based on clinical trial evidence [61,116,118].
- Pearl 7: SDH-deficient GIST are imatinib-resistant but may respond to sunitinib or regorafenib; germline testing is indicated [GIST-B].
- Pearl 8: Tumor response to TKIs is assessed by CT or MRI; Choi criteria may be more sensitive than RECIST for GIST [29], but RECIST is also used in practice.