The NAB2-STAT6 gene fusion in solitary fibrous tumor can be reliably detected by anchored multiplexed PCR for targeted next-generation sequencing.
Solitary fibrous tumor (SFT) is a mesenchymal tumor of fibroblastic origin, which can affect any region of the body. 10-15% of SFTs metastasize and metastatic tumors are uniformly lethal with no effective therapies. The behavior of SFT is difficult to predict based on morphology. Recently, an intrachromosomal gene fusion between NAB2 and STAT6 was identified as the defining driving genetic event of SFT and different fusion types correlated with tumor histology and behavior. Due to the proximity of NAB2 and STAT6 on chromosome 12, this fusion may be missed by fluorescence in-situ hybridization. We evaluated 12 SFTs from 10 patients. All tumors showed strong nuclear staining for STAT6 by immunohistochemistry (IHC). The same formalin-fixed, paraffin-embedded blocks for IHC were used for gene fusion detection by a next-generation sequencing (NGS)-based assay. Targeted RNA fusion sequencing for gene fusions was performed using the Universal RNA Fusion Detection Kit, the Archer(™) FusionPlex(™) Sarcoma Panel and the Ion Torrent PGM, and data were analyzed using the Archer Analysis Pipeline 3.3. All tumors were positive for NAB2-STAT6 fusion. Six types of fusions were detected: NAB2ex4-STAT6ex2, NAB2ex2-STAT6ex5, NAB2ex6-STAT6ex16, NAB2ex6-STAT6ex17, NAB2ex3-STAT6ex18 and NAB2intron6-STAT6Ex17. The NGS findings were confirmed by RT-PCR followed by Sanger sequencing. No STAT6 fusion was detected in selected morphologic mimics of SFT. The assay also allows for detection of novel fusions and can detect NAB2-STAT6 fusions at a single-base resolution.
Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
Natalya V
NV
Guseva
Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
Munir R
MR
Tanas
Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
Aaron A
AA
Stence
Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA; Iowa Institute of Human Genetics, University of Iowa, Iowa City, IA 52242, USA.
Ramakrishna
R
Sompallae
Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
Jenna C
JC
Schade
Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
Aaron D
AD
Bossler
Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA.
Andrew M
AM
Bellizzi
Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, USA. Electronic address: deqin-ma@uiowa.edu.
Deqin
D
Ma
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics; D005260:Female; D005820:Genetic Testing / Q000379:methods; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D060885:Multiplex Polymerase Chain Reaction / Q000379:methods*; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D012097:Repressor Proteins / Q000235:genetics; D015203:Reproducibility of Results; D012189:Retrospective Studies; D050800:STAT6 Transcription Factor / Q000235:genetics; D017423:Sequence Analysis, RNA / Q000379:methods*; D054364:Solitary Fibrous Tumors / Q000235:genetics*
D014408:Biomarkers, Tumor; C491000:NAB2 protein, human; D015514:Oncogene Proteins, Fusion; D012097:Repressor Proteins; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human
NAB2–STAT6; Solitary fibrous tumor; next-generation sequencing; targeted RNA sequencing