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Molecular alterations of KIT and PDGFRA in GISTs: evaluation of a Portuguese series
A L Gomes1, A Gouveia, A F Capelinha
1Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal.
Aim:
To assess KIT and PDGFRA mutations frequencies in a Portuguese series of gastrointestinal stromal tumours (GISTs).
Methods:
78 GISTs were evaluated for CD117 expression and screened for mutations in KIT (exons 9, 11, 13, 14 and 17) and PDGFRA (exons 12, 14 and 18) genes.
Results:
KIT activating mutations were identified in 44 (56%) of the 78 GISTs. Forty cases (91%) presented a mutation in KIT exon 11, and 4 (9%) in exon 9. One case showed a 4 bp deletion in intron 14. PDGFRA mutations were observed in 5 cases (6%): 2 (3%) in exon 12 and 3 (4%) in exon 18. Survival analysis was performed in 63 of the 78 GISTs. The presence of mutated KIT was significantly correlated with shorter survival of patients (p = 0.0460), and inversely associated with epithelioid histological type of GISTs (p = 0.0064).
Conclusions:
Overall, the incidence of both KIT and PDGFRA mutations in these Portuguese series was 63%, being in agreement with other studies, mainly of Iberian populations. The great majority of mutations were located in KIT exon 11, statistically associated with worse prognosis and indicative of favourable response to imatinib-based therapy in this Portuguese series of GISTs.
Insights
Gastrointestinal stromal tumours (GISTs) in Portugal show a 63% incidence of KIT and PDGFRA mutations. KIT exon 11 mutations correlate with worse prognosis and potential imatinib response.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract.
- Activating mutations in KIT and Platelet-Derived Growth Factor Receptor Alpha (PDGFRA) genes are key drivers in GIST pathogenesis.
- Understanding mutation frequencies and their clinical correlations is crucial for targeted therapy.
Purpose of the Study:
- To determine the frequency of KIT and PDGFRA gene mutations in a Portuguese cohort of GIST patients.
- To analyze the correlation between specific mutations and patient survival and histological subtypes.
Main Methods:
- Genomic DNA was extracted from 78 GIST tissue samples.
- Mutation screening was performed for KIT (exons 9, 11, 13, 14, 17) and PDGFRA (exons 12, 14, 18) using PCR and sequencing.
- Immunohistochemistry for CD117 and survival analysis were conducted.
Main Results:
- Activating KIT mutations were found in 56% of GISTs, predominantly in exon 11 (91% of KIT mutations).
- PDGFRA mutations occurred in 6% of cases, with mutations in exons 12 and 18.
- KIT mutations were significantly associated with shorter patient survival (p=0.0460) and inversely correlated with epithelioid histology (p=0.0064).
Conclusions:
- The overall mutation incidence of KIT and PDGFRA in this Portuguese GIST series was 63%, aligning with Iberian population studies.
- KIT exon 11 mutations are the most common and are linked to a worse prognosis.
- These findings support the role of KIT mutations as prognostic markers and potential indicators for imatinib therapy response in Portuguese GIST patients.
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