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Astolfi A, Indio V, Nannini M, Saponara M, Schipani A, De Leo A, Altimari A, Vincenzi B, Comandini D, Grignani G, Secchiero P, Urbini M, Pantaleo MA. Targeted Deep Sequencing Uncovers Cryptic KIT Mutations in KIT/PDGFRA/SDH/RAS-P Wild-Type GIST. Front Oncol 2020; 10:504. [PMID: 32391261 PMCID: PMC7188756 DOI: 10.3389/fonc.2020.00504] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 03/19/2020] [Indexed: 12/18/2022] Open
Abstract
Background: Gastrointestinal stromal tumors (GIST) are known to carry oncogenic KIT or PDGFRA mutations, or less commonly SDH or NF1 gene inactivation, with very rare cases harboring mutant BRAF or RAS alleles. Approximately 10% of GISTs are devoid of any of such mutations and are characterized by very limited therapeutic opportunities and poor response to standard treatments. Methods: Twenty-six sporadic KIT/PDGFRA/SDH/RAS-pathway wild type GIST were profiled for the molecular status of genes frequently altered in GIST by a targeted next generation sequencing (NGS) approach. Molecular findings were validated by alternative amplicon-based targeted sequencing, immunohistochemistry, gene expression profiling and Sanger sequencing. Results: Three patients harboring NF1 inactivating mutations were identified and excluded from further analysis. Intriguingly, five patients carried cryptic KIT alterations, mainly represented by low-allele-fraction mutations (12–16% allele ratio). These mutations were confirmed by another targeted NGS approaches and supported by CD117 immuno-staining, gene expression profiling, Sanger sequencing, with peak signals at the level of background noise, and by the patients' clinical course assessment. Conclusion: This study indicates that ~20% patients diagnosed with a KIT/PDGFRA/SDH/RAS-pathway wild-type GIST are bona-fide carriers of pathogenic KIT mutations, thus expected to be eligible for and responsive to the various therapeutic lines of TK-inhibitors in use for KIT/PDGFRA-mutant GIST. The centralization for a second level molecular analysis of GIST samples diagnosed as wild-type for KIT and PDGFRA is once again strongly recommended.
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Affiliation(s)
- Annalisa Astolfi
- Department of Morphology, Surgery & Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Valentina Indio
- "Giorgio Prodi" Cancer Research Center, University of Bologna, Bologna, Italy
| | - Margherita Nannini
- Department of Experimental, Diagnostic and Specialty Medicine, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy.,Medical Oncology Unit, S.Orsola-Malpighi University Hospital, Bologna, Italy
| | - Maristella Saponara
- Department of Experimental, Diagnostic and Specialty Medicine, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Angela Schipani
- "Giorgio Prodi" Cancer Research Center, University of Bologna, Bologna, Italy
| | - Antonio De Leo
- Department of Experimental, Diagnostic and Specialty Medicine, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
| | - Annalisa Altimari
- Laboratory of Oncologic Molecular Pathology, S. Orsola-Malpighi Hospital, Bologna, Italy
| | - Bruno Vincenzi
- Department of Medical Oncology, University Campus Bio-Medico, Rome, Italy
| | - Danila Comandini
- Medical Oncology 1, Policlinico San Martino, University of Genova, Genova, Italy
| | - Giovanni Grignani
- Sarcoma Unit, Candiolo Cancer Institute - FPO, IRCCS, Candiolo, Italy
| | - Paola Secchiero
- Department of Morphology, Surgery & Experimental Medicine, University of Ferrara, Ferrara, Italy
| | - Milena Urbini
- "Giorgio Prodi" Cancer Research Center, University of Bologna, Bologna, Italy
| | - Maria Abbondanza Pantaleo
- "Giorgio Prodi" Cancer Research Center, University of Bologna, Bologna, Italy.,Department of Experimental, Diagnostic and Specialty Medicine, S. Orsola-Malpighi Hospital, University of Bologna, Bologna, Italy
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