Finally any equivocal cases should be sent for genomic BRAF V600 assessment

Finally any equivocal cases should be sent for genomic BRAF V600 assessment. Although the sensitivity and negative predictive value of BRAF IHC in our study was also high, 94.4% and 93.3%, respectively, it is known to miss patients with non-V600E BRAF mutations. V600E2 mutation and an inability of the IHC staining technique to detect non-V600E mutations. Molecular testing on smaller tumour deposits was also unreliable. Conclusions: IHC staining has good sensitivity and excellent specificity for BRAF V600E mutations. BRAF IHC can be incorporated into a BRAF mutation testing algorithm for UK cancer centres to as a feasible first-line assay and identify a subset of cases that require subsequent genomic testing. It has the additional major advantages of reduced cost and rapid turnaround time. strong class=”kwd-title” Keywords: BRAF V600 mutation, melanoma, VE1 monoclonal antibody, immunohistochemistry The BRAF mutation in melanoma was first described in a landmark paper in 2002 (Davies em et al /em , 2002). Mutations in BRAF are present in 41C56% of malignant melanomas (Lee em et al /em , 2011; Sosman em et al /em , 2012). They are most prevalent in cutaneous lesions of superficial spreading and nodular types, whereas they occur at a lower frequency in acral and lentigo maligna melanomas (Saldanha em et al /em , 2006; Lee em et al /em , 2011). The mutations are almost exclusively missense and cluster at the kinase domain resulting in an increased kinase activity (Davies em et al /em , 2002; Lee em et al /em , 2011; COSMIC, 2014). The most common BRAF mutation, a single amino acid substitution of valine for glutamic acid at residue 600 (V600E), occurs in 90% of mutated cases. A lysine to valine substitution (V600K), accounts for a further 5C6% while rarer BRAF mutations, such as V600E2, other V600 mutations, and non-V600 changes collectively comprise the remaining 4%. Novel drugs, specifically aimed at inhibiting the overstimulation of the MAP-kinase cell-signalling pathway have revolutionised the treatment of unresectable or metastatic melanoma (Long em et al /em , 2011). Over half of patients with BRAF V600-mutated metastatic melanoma had a clinical response to a BRAF inhibitor in a phase Runx2 II clinical trial (Sosman em et al /em , 2012), with further studies, including phase III trials, demonstrating an improved overall survival in patients treated with BRAF inhibitors compared with standard therapy (Flaherty em et al /em , 2010; Chapman em et al /em , 2011; Long em et al /em , 2011; Hauschild em et al /em , 2012; Sosman em et al /em , 2012; McArthur em et al /em , 2014). BRAF inhibitors are the current therapy of choice for patients with BRAF V600-mutated metastases following the publication of the UK NICE appraisal document in 2012 (National Institute for Health and Care Excellence, 2012). Rapid BRAF mutation testing is therefore essential when considering the appropriate treatment pathway for these patients, particularly for those presenting with rapidly progressing, advanced and unresectable disease. Moreover, ascertaining BRAF status in metastatic melanoma facilitates patients’ entry into clinical trials with BRAF inhibitors. There are several methods to detect BRAF mutations including immunohistochemistry (IHC), pyrosequencing, Sanger sequencing and real-time PCR (Colomba em et al /em , 2013; Long em et al /em , 2013; Just em et Mitoxantrone Hydrochloride al /em , 2014; Thiel em et al /em , 2015). Table 1 highlights the abilities of these techniques to detect the various mutations. Before this study, all patients managed within the specialist skin multidisciplinary team (MDT) at our two centres required melanoma samples to be dispatched to a national molecular testing centre and tested using a real-time PCR test, the COBAS technique. The advantage of this system is that the diagnostic expertise is centralised to a limited number of high-volume centres, thereby maximising the quality assurance. The drawback is that it is relatively Mitoxantrone Hydrochloride time-consuming and has a limited Mitoxantrone Hydrochloride capacity. The VE1 antibody clone has been validated and shown to detect the V600E and the rarer V600E2-mutated variants with a sensitivity and specificity of 95C100% and 97C100%, respectively, (Long em et al /em , 2011; Colomba em et al /em , 2013; Just em et al /em , 2014; Pearlstein em et al /em , 2014; Thiel em et al /em , 2015), although data from UK-based centres were lacking. IHC may be preferable for routine clinical use since it is quicker, cheaper and can be offered by more histopathology laboratories. However, since the antibody does not identify the less common V600K, V600R and non-V600 mutations, the overall sensitivity of IHC to detect BRAF mutations when compared with genomic methods is reported to be 76C89% (Long em et al /em , 2011; Just em et al /em , 2014; Thiel em et al /em , 2015). Table 1 Ability of the different assays to test for the most common BRAF mutations. The frequency of their occurrence in.