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INVESTIGATIVE REPORT Advances in dermatology and venereology ActaDV Acta Dermato-Venereologica ActaDV
Evaluation of a Rapid , Fully Automated Platform for Detection of BRAF and NRAS Mutations in Melanoma
Fanny BAREL 1 , Briac GUIBOURG 1 , Laetitia LAMBROS 1 , Glen LE FLAHEC 1 , Pascale MARCORELLES 1 , 2 and Arnaud UGUEN 1 – 3
1
CHRU Brest , Department of Pathology , 2 European University of Brittany , and 3 INSERM , U1078 , Brest , France
BRAF and NRAS genetic analyses are time-consuming and can delay treatment choices in patients with metastatic melanomas presenting with acute deterioration . We compared the rapid , real-time , fully automated molecular diagnosis platform Idylla™ with next-generation sequencing ( NGS ) and immunohistochemistry for detection of BRAF and NRAS mutations in 36 patients with metastatic melanomas . The Idylla™ NRAS-BRAF-EGFRS492R mutation assay ( 110 min per sample ) detected BRAF and NRAS mutations in 15 and 17 samples , respectively . One NRAS mutation was different between NGS and Idylla™ ( NRASG13C vs . NRASG12A / D ). Four samples were BRAF and NRAS wild-type . The global concordance between NGS and Idylla™ assays was 97.2 % ( 35 / 36 cases ). Immunohistochemistry was positive only in 9 / 9 BRAFV600Eand 6 / 6 NRASQ61R-mutated samples with VE1 and SP174 antibodies , respectively . The Idylla™ platform is a valuable rapid molecular diagnosis tool to reduce the delay in BRAF and NRAS analyses-related treatment choices for patients with metastatic melanoma presenting with acute deterioration .
Key words : melanoma ; BRAF ; NRAS ; immunohistochemistry ; Idylla ; next-generation sequencing .
Accepted Jun 28 , 2017 ; Epub ahead of print Jun 29 , 2017 Acta Derm Venereol 2018 ; 98 : 44 – 49 .
Corr : Arnaud Uguen , Department of Pathology , University Hospital Morvan , 5 , Avenue Foch , FR-29609 Brest , France . E-mail : arnaud . uguen @ chu-brest . fr
Melanoma is a frequent and aggressive skin cancer with a high rate of mortality at the metastatic stage ( 1 – 3 ). The management of patients with metastatic melanoma has improved recently with immunotherapy and molecular-targeted therapy ( 4 – 7 ). Current moleculartargeted therapies consist mainly of BRAF and MEK inhibitors used in patients with BRAF-mutated metastatic melanomas , which represent approximately 50 % of melanomas ( 4 , 5 , 8 ). In contrast , there is currently no approved targeted therapy to inhibit NRAS mutant proteins , which are detected in approximately 15 % of melanomas , and patients with NRAS-mutated metastatic melanomas are treated with immunotherapy ( 6 – 8 ). Thus , the determination of BRAF and NRAS mutation status in melanoma samples is now a major criterion for treatment choices ( 9 , 10 ).
The method of detection of BRAF and NRAS mutation should be accurate , highly sensitive to detect low mutant allele frequency , and fast enough to provide useful information allowing rapid treatment choice in patients with metastatic melanomas . The vast majority of samples analysed for mutation testing are formalin-fixed and paraffin-embedded ( FFPE ) melanoma samples from pathology centres . In addition to the DNA-based , PCRbased , and sequencing methods , such as next-generation sequencing ( NGS ), mutation-specific immunohistochemistry ( IHC ) has emerged recently as an efficient and more rapid tool in comparison with sequencing to detect BRAFV600E and NRASQ61R mutant proteins in FFPE melanoma samples using the clones VE1 and SP174 , respectively ( 11 – 15 ). Although BRAFV600E and NRASQ61R mutations represent approximately 90 % of BRAF mutations and 40 % of NRAS mutations in melanoma , respectively , other BRAFV600 and NRAS mutations in codons 12 , 13 and 61 are also relevant for treatment choice , but are not detected with clones VE1 and SP174 . Thus , the detection of different BRAFV600 and NRAS codons 12 , 13 and 61 mutations still requires expensive molecular biology equipment and a dedicated laboratory with staff highly skilled in molecular methods , in order to provide a clinically relevant BRAF and NRAS mutation status to the clinicians . The molecular testing process of a tumour sample can last several days to weeks depending on institutions , which can delay the start of targeted therapy or immunotherapy in patients with metastatic melanomas ( 16 ).
Recently , a fully automated real-time PCR Idylla™ platform has been developed to provide rapid detection ( less than 2 h ) of BRAF mutation in FFPE melanoma samples ( 17 – 20 ). It has shown excellent performances in comparison with other DNA-based methods , including NGS , but also with BRAFV600E mutation-specific IHC . However , until recently , this platform did not provide any information about NRAS mutation status , which still required additional sequencing analyses with an alternative method in melanomas .
The aim of the present study is to compare the new Idylla™ fully-automated platform with NGS and mutation-specific IHC to detect BRAF and NRAS mutations in melanoma samples . This is the first report of a rapid , fully automated real-time PCR method enabling the detection of BRAF and NRAS mutations in the same assay in melanomas . doi : 10.2340 / 00015555-2738 Acta Derm Venereol 2018 ; 98 : 44 – 49
This is an open access article under the CC BY-NC license . www . medicaljournals . se / acta Journal Compilation © 2018 Acta Dermato-Venereologica .