From these data we conclude that activating c-KIT and PDGFR mutations are sporadic in human cancers known to overexpress these tyrosine kinase receptor genes and suggest that, except in GIST, this overexpression is not correlated with activating mutations.
Approximately 85% of GISTs are driven by oncogenic mutations in either of two receptor tyrosine kinases: KIT or platelet-derived growth factor receptor alpha.
Gastrointestinal stromal tumors (GIST) are stromal or mesenchymal subepithelial neoplasms affecting the gastrointestinal tract and frequently contain activating gene mutations in either KIT or platelet-derived growth factor A (PDGFRA).
The clinico-pathological and genetic factors influencing disease-free survival (DFS) in 335 patients with primary CD117-immunopositive tumors (group A; calculated from primary tumor resection) and progression-free survival (PFS) in 232 metastatic/unresectable GIST patients treated with IM (group B; calculated from the start of imatinib therapy) were analyzed.
Mutations in exon 9 of KIT were present in 5.1% of the gastrointestinal stromal tumors, and mutations of the PDGFR were present in 11% of the KIT -nonmutated tumors.
Gene mutations of KIT or PDGFRA are critical in GISTs, because the aberrant versions not only are correlated with the specific cell morphology, histologic phenotype, metastasis, and prognosis, but also are the targets of therapy with imatinib and other agents.
Gastrointestinal stromal tumors (GIST) are the most common soft tissue sarcoma of the gastrointestinal tract, resulting most commonly from KIT or platelet-derived growth factor receptor α (PDGFRα)-activating mutations.
Multivariate analysis showed shorter PFS in patients who had higher residual SUVs (P < .0001), primary resistance to imatinib (P = .024), or nongastric GIST (P = .002), regardless of the mutational status of the KIT and PDGFRA genes.
A molecular analysis was performed for all suspicions of sarcomas with specific genetic lesions [mutations of KIT/PDGFRA in gastrointestinal stromal tumors (GISTs), reciprocal translocation, or amplification of MDM2 in atypical lipomatous tumors, well-differentiated liposarcoma-dedifferentiated liposarcoma (ALT/WDLPS-DDLPS)].
We report for the first time an integrated genomic picture of KITWT/PDGFRAWT/SDHWT/RAS-PWT GIST, using massively parallel sequencing and gene expression analyses, and found that quadrupleWT GIST have an expression signature that is distinct from SDH-mutant GIST as well as GIST harbouring mutations in KIT or PDGFRA.
Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and are caused by activating mutations of the KIT or platelet-derived growth factor receptor alpha (PDGFRA) tyrosine kinases.
Whereas KIT juxtamembrane domain mutations seen in most patients with GIST are highly sensitive to imatinib, the kinase activation loop mutant D816V, frequently encountered in SM, hampers the binding ability of imatinib.
Immunohistochemical analysis for MAX on a large panel of GISTs identified loss of MAX expression in the MAX-mutated GIST and in a subset of mainly KIT-mutated tumors.