Multiple Gastrointestinal Stromal and Other Tumors Caused by Platelet-Derived Growth Factor Receptor Gene Mutations: A Case Associated with a Germline V561D Defect (original) (raw)
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The Journal of Clinical Endocrinology & Metabolism, 2007
Context: Gastrointestinal stromal tumors (GISTs) may be caused by somatic or germline mutations of the KIT and PDGFRA genes, but most GISTs associated with neuroendocrine tumors (NETs) are not, suggesting that other molecular pathways are implicated in their pathogenesis. Objective: In the course of investigating NETs and GIST genetics, we encountered a patient who had a unique combination of multiple fibrous polyps and lipomas of the small intestine and several gastric GISTs. Design: The study included the clinical description of a unique patient, DNA sequencing of germline and tumor DNA, and comparative genomic hybridization (CGH) and allelic marker analysis of tumor DNA. Results: The patient was found to carry a germline PDGFRA mutation (V561D) in the heterozygote state; it has only been seen rarely
KIT and PDGFRA mutations in gastrointestinal stromal tumors (GISTs)
Seminars in Diagnostic Pathology, 2006
Mutually exclusive KIT and PDGFRA mutations are central events in GIST pathogenesis, and their understanding is becoming increasingly important, because specific treatment targeting oncogenic KIT and PDGFRA activation (especially imatinib mesylate) has become available. KIT mutations in GIST are clustered in four exons. Most common are exon 11 (juxtamembrane domain) mutations that include deletions, point mutations (affecting a few codons), and duplications (mostly in the 3= region). The latter mutations most often occur in gastric GISTs. Among gastric GISTs, tumors with deletions are more aggressive than those with point mutations; this does not seem to hold true in small intestinal GISTs. Exon 9 mutations (5-10%) usually are 2-codon 502-503 duplications, and these occur predominantly in intestinal versus gastric GISTs. Lesser imatinib sensitivity of these tumors has been noted. Kinase domain mutations are very rare; GISTs with such mutations are variably sensitive to imatinib. PDGFRA mutations usually occur in gastric GISTs, especially in the epithelioid variants; their overall frequency is approximately 30% to 40% of KIT mutation negative GISTs. Most common is exon 18 mutation leading Asp842Val at the protein level. This mutation causes imatinib resistance. Exon 12 and 14 mutations are rare. Most mutations are somatic (in tumor tissue only), but patients with familial GIST syndrome have consitutitonal KIT/PDGFRA mutations; Ͼ10 families have been reported worldwide with mutations generally similar to those in sporadic GISTs. GISTs in neurofibromatosis 1 patients, children, and Carney triad seem to lack GIST-specific KIT and PDGFRA mutations and may have a different disease mechanism. Secondary mutations usually occur in KIT kinase domains in patients after imatinib treatment resulting in resistance to this drug. Mutation genotyping is a tool in GIST diagnosis and in assessment of sensitivity to kinase inhibitors. This is a US government work. There are no restrictions on its use. The opinions and assertions contained herein are the expressed views of the authors and are not to be construed as official or reflecting the views of the Departments of the Army or Defense.
Molecular Subtypes ofKIT/PDGFRAWild-Type Gastrointestinal Stromal Tumors
JAMA Oncology, 2016
IMPORTANCE Wild-type (WT) gastrointestinal stromal tumors (GISTs), which lack KIT and PDGFRA gene mutations, are the primary form of GIST in children and occasionally occur in adults. They respond poorly to standard targeted therapy. Better molecular and clinical characterization could improve management. OBJECTIVE To evaluate the clinical and tumor genomic features of WT GIST. DESIGN, SETTING, AND PARTICIPANTS Patients enrolled in an observational study at the National Institutes of Health starting in 2008 and were evaluated in a GIST clinic held once or twice yearly. Patients provided access to existing medical records and tumor specimens. Self-referred or physician-referred patients younger than 19 years with GIST or 19 years or older with known WT GIST (no mutations in KIT or PDGFRA) were recruited; 116 patients with WT GIST were enrolled, and 95 had adequate tumor specimen available. Tumors were characterized by immunohistochemical analysis (IHC) for succinate dehydrogenase (SDH) subunit B, sequencing of SDH genes, and determination of SDHC promoter methylation. Testing of germline SDH genes was offered to consenting patients and families. MAIN OUTCOMES AND MEASURES For classification, tumors were characterized by SDHA, B, C, or D (SDHX) mutations and other genetic and epigenetic alterations, including presence of mutations in germline. Clinical characteristics were categorized. RESULTS Wild-type GIST specimens from 95 patients (median age, 23 [range, 7-78] years; 70% female) were classified into 3 molecular subtypes: SDH-competent (n = 11), defined by detection of SDHB by IHC; and 2 types of SDH-deficient GIST (n = 84). Of SDH-deficient tumors, 63 (67%) had SDH mutations, and in 31 of 38 (82%), the SDHX mutation was also present in germline. Twenty-one (22%) SDH-deficient tumors had methylation of the SDHC promoter leading to silencing of expression. Mutations in known cancer-associated pathways were identified in 9 of 11 SDH-competent tumors. Among patients with SDH-mutant tumors, 62% were female (39 of 63), median (range) age was 23 (7-58) years, and approximately 30% presented with metastases (liver [12 of 58], peritoneal [6 of 58], lymph node [15 of 23]). SDHC-epimutant tumors mostly affected young females (20 of 21; median [range] age, 15 [8-50] years), and approximately 40% presented with metastases (liver [7 of 19], peritoneal [1 of 19], lymph node [3 of 8]). SDH-deficient tumors occurred only in the stomach and had an indolent course. CONCLUSIONS AND RELEVANCE An observational study of WT GIST permitted the evaluation of a large number of patients with this rare disease. Three molecular subtypes with implications for prognosis and clinical management were identified.
Laboratory Investigation, 2004
Gastrointestinal stromal tumors (GISTs) are KIT expressing spindle cell, epithelioid and rarely pleomorphic mesenchymal tumors. The majority of GISTs show gain-of-function KIT mutations. However, GISTs without KIT mutations and GISTs with weak or lack of immunohistochemical KIT expression have also been reported. Recently, gain-of-function mutations in exon 18 (activation loop) and exon 12 (juxtamembrane domain) of the PDGFRA were identified in such tumors. The purpose of this study was to test the hypothesis that PDGFRA mutation may define a specific clinicopathologic subgroup of GISTs. A total of 447 KIT exon 11 (juxtamembrane domain) mutation-negative GISTs were studied. DNA samples were obtained from formaldehyde-fixed paraffinembedded tissues. Genomic sequences of PDGFRA exons 18 and 12 were evaluated for the mutations by PCR amplification and direct sequencing. PDGFRA exon 18 mutations were identified in 122 of 346 (35.3%) gastric GISTs and two of 75 (2.7%) intestinal GISTs. A great majority of these mutations represented simple T to A missense mutation at the codon 842 leading to substitution of the valine for aspartic acid (D842 V). However, inframe deletions and deletions with point mutations clustering between codons 841-847 were found in approximately 23% of all exon 18 mutations. Mutations in PDGFRA exon 12 were found only in 10 of 170 (5.8%) gastric and one of 54 (1.9%) intestinal GISTs negative for KIT exon 11 and PDGFRA exon 18 mutations. There were seven substitutions of aspartic acid for valine at codon 561 (V561D) and four in-frame deletions with point mutations clustering between codons 566 and 571. The majority of GISTs with PDGFRA mutations had pure or predominant epithelioid morphology. Low mitotic activity, r5 mitoses/50HPF was detected in 81% of analyzed GISTs including larger, 45 cm tumors. Based on long-term follow-up (average 135 months), a majority (83.5%) of GISTs with PDGFRA mutations followed a benign course.
Pediatr Dev Pathol, 2005
A diagnosis of multiple gastric stromal tumors that were nonmetastatic at presentation was made in an 11-yearold girl who presented with hematemesis. Gastrointestinal stromal tumor (GIST) is a rare diagnosis in childhood and reported multiple lesions are generally seen in the context of familial disease, occasionally with syndromic associations. Although there are no reports of genetic mutation in cases of pediatric GIST, very many cases of multiple GISTs investigated on a molecular level have shown germline KIT or platelet-derived growth factor receptor-a mutation; these were familial cases. Despite the negative family history in our patient, the multiplicity of lesions in such a young patient raised concern for a genetic predisposition and prompted extensive molecular workup. Repeat evaluation of distinct aliquots of tumor tissue by polymerase chain amplification followed by sequence analysis of selected coding sequences of KIT and platelet-derived growth factor receptor-a previously shown to harbor mutations in GIST, yielded no evidence of even a somatic mutation. This clinically unique case is discussed in the context of a literature review.
2008
Background: The prognostic significance of KIT or platelet-derived growth factor receptor a (PDGFRa) mutations in gastrointestinal stromal tumors (GISTs) is still controversial. Patients and methods: In all, 104 patients were diagnosed with GISTs by KIT immunoreactivity; tumor DNA was sequenced for the presence of mutations in KIT exons 9, 11, 13 and 17 and in PDGFRa exons 12 and 18. Diseasefree survival (DFS) was analyzed in 85 radically resected patients. Results: KIT mutations occurred in exon 11 (69), in exon 9 (11) and in exon 17 (1). PDGFRa mutations were detected in exon 18 (10) and in exon 12 (3). Ten GISTs were wild type. Exon 11 mutations were as follows: deletions in 42 cases and point mutations in 20 cases and insertions and duplications, respectively, in 2 and 5 cases. A better trend in DFS was evident for duplicated and point-mutated exon 11 KIT GISTs. There was a significant association between PDGFRa mutations, gastric location and lower mitotic index. Moreover, PDGFRa-mutated GISTs seemed to have a better outcome. Conclusions: Point mutations and duplications in KIT exon 11 are associated with a better clinical trend in DFS. PDGFRa-mutated GISTs are preferentially localized in the stomach and seem to have a favorable clinical behavior.