Screening for ROS1 gene rearrangements in non-small-cell lung cancers using immunohistochemistry with FISH confirmation is an effective method to identify this rare target.

AIMS: To assess the prevalence of ROS1 rearrangements in a retrospective and prospective diagnostic Australian cohort and evaluate the effectiveness of immunohistochemical screening. METHODS AND RESULTS: A retrospective cohort of 278 early stage lung adenocarcinomas and an additional 104 prospective non-small-cell lung cancer (NSCLC) cases referred for routine molecular testing were evaluated. ROS1 immunohistochemistry (IHC) was performed (D4D6 clone, Cell Signaling Technology) on all cases as well as fluorescence in-situ hybridization (FISH) using the ZytoVision and Abbott Molecular ROS1 FISH probes, with ≥15% of cells with split signals considered positive for rearrangement. Eighty-eight cases (32%) from the retrospective cohort showed staining by ROS1 IHC, and one case (0.4%) showed ROS1 rearrangement by FISH. Nineteen of the prospective diagnostic cases showed ROS1 IHC staining, 12 (12%) cases of which were confirmed as ROS1 rearranged by FISH. There were no ROS1 rearranged cases that showed no expression of ROS1 with IHC. The ROS1 rearranged cases in the prospective cohort were all EGFR wild-type and anaplastic lymphoma kinase (ALK) rearrangement-negative. The sensitivity of ROS1 IHC in the retrospective cohort was 100% and specificity was 76%. CONCLUSIONS: ROS1 rearrangements are rare events in lung adenocarcinomas. Selection of cases for ROS1 FISH testing, by excluding EGFR/ALK-positive cases and use of IHC to screen for potentially positive cases, can be used to enrich for the likelihood of identifying a ROS1 rearranged lung cancer and prevent the need to undertake expensive and time-consuming FISH testing in all cases.

LAT1 is a putative therapeutic target in endometrioid endometrial carcinoma.

l-type amino acid transporters (LAT1-4) are expressed in various cancer types and are involved in the uptake of essential amino acids such as leucine. Here we investigated the expression of LAT1-4 in endometrial adenocarcinoma and evaluated the contribution of LATs to endometrial cancer cell growth. Analysis of human gene expression data showed that all four LAT family members are expressed in endometrial adenocarcinomas. LAT1 was the most highly expressed, and showed a significant increase in both serous and endometrioid subtypes compared to normal endometrium. Endometrioid patients with the highest LAT1 levels exhibited the lowest disease-free survival. The pan-LAT inhibitor BCH led to a significant decrease in cell growth and spheroid area in four endometrial cancer cell lines tested in vitro. Knockdown of LAT1 by shRNA inhibited cell growth in HEC1A and Ishikawa cells, as well as inhibiting spheroid area in HEC1A cells. These data show that LAT1 plays an important role in regulating the uptake of essential amino acids such as leucine into endometrial cancer cells. Increased ability of BCH compared to LAT1 shRNA at inhibiting Ishikawa spheroid area suggests that other LAT family members may also contribute to cell growth. LAT1 inhibition may offer an effective therapeutic strategy in endometrial cancer patients whose tumours exhibit high LAT1 expression.

BRAF(V600E) and NRAS(Q61L/Q61R) mutation analysis in metastatic melanoma using immunohistochemistry: a study of 754 cases highlighting potential pitfalls and guidelines for interpretation and reporting.

BACKGROUND AND AIMS: BRAF or NRAS mutations occur in approximately 60% of cutaneous melanomas, and the identification of such mutations underpins the appropriate selection of patients who may benefit from BRAF and MEK inhibitor targeted therapies. The utility of immunohistochemistry (IHC) to detect NRAS(Q61L) mutations is currently unknown. This study sought to assess the sensitivity and specificity of anti-BRAF(V600E) (VE1), anti-NRAS(Q61R) (SP174) and anti-NRAS(Q61L) (26193) antibodies for mutation detection in a large series of cases. METHODS AND RESULTS: Mutation status was determined using the OncoCarta assay in 754 cutaneous melanomas. IHC with the anti-BRAF(V600E) antibody was performed in all cases, and the anti-NRAS(Q61R) and anti-NRAS(Q61L) antibodies were assessed in a subset of 302 samples utilizing tissue microarrays. The staining with the anti-BRAF(V600E) and anti-NRAS(Q61R) antibodies was diffuse, homogeneous and cytoplasmic. The anti-NRAS(Q61L) antibody displayed variable intensity staining, ranging from weak to strong in NRAS(Q61L) mutant tumours. The sensitivity and specificity for anti-BRAF(V600E) was 100 and 99.3%, anti-NRAS(Q61R) was 100 and 100% and anti-NRAS(Q61L) was 82.6 and 96.2%, respectively. CONCLUSIONS: The use of IHC is a fast, efficient and cost-effective method to identify single specific mutations in melanoma patients. BRAF(V600E) and NRAS(Q61R) antibodies have high sensitivity and specificity; however, the NRAS(Q61L) antibody appears less sensitive. IHC can help to facilitate the timely, appropriate selection and treatment of metastatic melanoma patients with targeted therapies. Detection of melanoma-associated mutations by IHC may also provide evidence for a diagnosis of melanoma in metastatic undifferentiated neoplasms lacking expression of melanoma antigens.

Dynamics of chemokine, cytokine, and growth factor serum levels in BRAF-mutant melanoma patients during BRAF inhibitor treatment.

The purpose of this study is to profile the changes in the serum levels of a range of chemokines, cytokines, and growth and angiogenic factors in MAPK inhibitor-treated metastatic melanoma patients and to correlate these changes with clinical outcome and changes in melanoma tissue biopsies taken from the same patients. Forty-two chemokine, cytokine, angiogenic, and growth factors were measured in the sera of 20 BRAF inhibitor-treated and four combination BRAF and MEK inhibitor-treated metastatic melanoma patients using a multiplex chemokine assay. The changes were correlated with Ki-67 and CD8(+) tumor-infiltrating lymphocytes in the tumor biopsies taken at the same time points, as well as clinical outcome, including response rate, progression-free survival, and overall survival. Serum levels of IFN-γ, CCL4, and TNF-α were significantly increased, whereas CXCL8 significantly decreased from pretreatment (PRE) to early during treatment (EDT) serum samples. The decrease in serum CXCL8 levels from PRE to EDT significantly correlated with decreases in markers of melanoma proliferation (Ki-67) and increases in cytotoxic tumor-infiltrating T cells in corresponding tumor biopsies. In addition, a greater fold reduction in CXCL8 serum levels from PRE to EDT serum samples was associated with decreased overall survival. These results suggest that BRAF inhibition causes decreased CXCL8 secretion from melanoma cells and induce an immune response against the tumor associated with increased IFN-γ, CCL4, and TNF-α. Further studies are needed to determine if CXCL8 is predictive of response and to confirm the functions of these chemokine and cytokine in BRAF-mutant melanoma under BRAF inhibition.

Equivocal ALK fluorescence in-situ hybridization (FISH) cases may benefit from ancillary ALK FISH probe testing.

AIMS: Accurate assessment of anaplastic lymphoma kinase (ALK) gene rearrangement in non-small-cell lung cancers (NSCLCs) is critical to identify patients who are likely to respond to crizotinib. The aim of this study was to evaluate the ALK/EML4 TriCheck FISH probe in a series of NSCLCs enriched for tumours with equivocal ALK status. METHODS AND RESULTS: ALK FISH was prospectively performed on 45 NSCLCs with the ALK/EML4 TriCheck probe (ZytoVision) and the Vysis ALK break-apart probe (Abbott Molecular). ALK immunohistochemistry was performed with 5A4 and D5F3 antibodies. Fourteen cases had equivocal ALK status, based on borderline or focal FISH positivity, an atypical FISH pattern, or discrepancy between ALK FISH and immunohistochemistry. Four of the 14 equivocal cases showed discordance between the two FISH probes. All other cases were concordant. The TriCheck probe showed that, of 31 unequivocal cases, 15 were ALK-rearranged, and 60% of these had EML4 as the translocation partner. Within the group of 14 equivocal cases, 12 showed rearrangement with the Tricheck probe; only one of these showed EML4 rearrangement. Of the six equivocal cases that received crizotinib, four showed clinical benefit. CONCLUSIONS: The ALK/EML4 TriCheck FISH probe may be useful for the detection of ALK rearrangements, especially in borderline or atypical cases, where an additional unique ALK FISH probe may provide further confirmation of rearrangement.

Real-world programmed death-ligand 1 prevalence rates in non-small cell lung cancer: correlation with clinicopathological features and tumour mutation status.

AIMS: The detection of programmed death-ligand 1 (PD-L1) protein expression on tumour cells by immunohistochemistry (IHC) is a predictor of response to immune checkpoint inhibitors. New immunotherapeutic options are changing the treatment paradigm for patients with advanced non-small cell lung cancer (NSCLC). The aim of this retrospective study was to investigate real-world prevalence of PD-L1 expression in NSCLC and any correlations with clinicopathological features. METHODS: We reviewed 425 NSCLC cases at a Sydney metropolitan hospital that had PD-L1 IHC (SP263 clone) expression estimated as part of routine diagnostic assessment during a 30-month period. RESULTS: Overall, 32.2% of cases were negative for PD-L1 expression (<1%), 40.3% demonstrated low expression (1%-49%) and 27.5% exhibited high protein expression (≥50%). High PD-L1 expression rates were more likely in non-lung resection cases and in KRAS mutant NSCLC as opposed to KRAS wildtype, while lower expression rates were more commonly found in EGFR mutant NSCLC compared with EGFR wildtype tumours. CONCLUSIONS: Ongoing observation and comparison of PD-L1 expression rates is an important practice for ensuring its validity as a predictive biomarker. The results from our study align with and contribute to the growing field of published real-world PD-L1 prevalence rates in NSCLC.

Programmed death ligand-1 (PD-L1) as a predictive marker for immunotherapy in solid tumours: a guide to immunohistochemistry implementation and interpretation.

Immunotherapy with checkpoint inhibitors is well established as an effective treatment for non-small cell lung cancer and melanoma. The list of approved indications for treatment with PD-1/PD-L1 checkpoint inhibitors is growing rapidly as clinical trials continue to show their efficacy in patients with a wide range of solid tumours. Clinical trials have used a variety of PD-L1 immunohistochemical assays to evaluate PD-L1 expression on tumour cells, immune cells or both as a potential biomarker to predict response to immunotherapy. Requests to pathologists for PD-L1 testing to guide choice of therapy are rapidly becoming commonplace. Thus, pathologists need to be aware of the different PD-L1 assays, methods of evaluation in different tumour types and the impact of the results on therapeutic decisions. This review discusses the key practical issues relating to the implementation of PD-L1 testing for solid tumours in a pathology laboratory, including evidence for PD-L1 testing, different assay types, the potential interchangeability of PD-L1 antibody clones and staining platforms, scoring criteria for PD-L1, validation, quality assurance, and pitfalls in PD-L1 assessment. This review also explores PD-L1 IHC in solid tumours including non-small cell lung carcinoma, head and neck carcinoma, triple negative breast carcinoma, melanoma, renal cell carcinoma, urothelial carcinoma, gastric and gastroesophageal carcinoma, colorectal carcinoma, hepatocellular carcinoma, and endometrial carcinoma. The review aims to provide pathologists with a practical guide to the implementation and interpretation of PD-L1 testing by immunohistochemistry.

p16 expression in cutaneous squamous cell carcinoma of the head and neck is not associated with integration of high risk HPV DNA or prognosis.

Head and neck cutaneous squamous cell carcinoma (HNcSCC) can present with cervical metastases without an obvious primary. Immunohistochemistry for p16 is established as a surrogate marker of human papillomavirus (HPV) in oropharyngeal cancer. p16 expression in HNcSCC needs to be elucidated to determine its utility in predicting the primary site. The aim of this study was to evaluate the rate of p16 expression in HNcSCC and its association with prognostic factors and survival. p16 immunohistochemistry was performed on 166 patients with high risk HNcSCC (2000-2013) following histopathology review. Chromogenic in situ hybridisation (CISH) for HPV was performed. Fifty-three (31.9%) cases showed strong, diffuse nuclear and cytoplasmic p16 expression including 14 (41%) non-metastatic and 39 (29.5%) metastatic tumours (p=0.21). HPV CISH was negative in all cases. p16 expression significantly increased with poorer differentiation (p=0.033), but was not associated with size (p=0.30), depth of invasion (p=0.94), lymphovascular invasion (p=0.31), perineural invasion (p=0.69), keratinisation (p=0.99), number of involved nodes (p=0.64), extranodal extension (p=0.59) or survival. Nearly 32% of HNcSCCs, particularly poorly differentiated HNcSCCs, show p16 expression. A primary HNcSCC should be considered in p16 positive neck node metastases in regions with high prevalence of HNcSCC. p16 expression is not associated with improved survival in HNcSCC.

PD-L1 expression predicts longer disease free survival in high risk head and neck cutaneous squamous cell carcinoma.

Programmed cell death (PD-1) and its ligand (PD-L1) inhibitors have shown clinical response in many tumours. PD-L1 data are limited in head and neck cutaneous squamous cell carcinoma (HNcSCC) and no clinical trials of PD-1/PD-L1 inhibitors are published. We performed PD-L1 immunohistochemistry on 74 cases of high risk HNcSCC with 38 matched metastases and evaluated clinicopathological associations, prognostic significance and heterogeneity in matched metastases. We observed PD-L1 expression in >5% of primary tumour cells in 29 cases (39.2%), primary tumour infiltrating lymphocytes (TILs) in 40 cases (70.2%), metastatic tumour cells in 15 cases (39.5%), and metastatic TILs in 18 cases (47.4%). PD-L1 expression in >5% of primary tumour cells was associated with an inflammatory phenotype (p = 0.04), and in primary TILs with clear margins (p = 0.05). PD-L1 expression in >5% of primary tumour cells (p = 0.01), primary TILs (p = 0.001), and metastatic TILs (p = 0.02) was associated with improved disease free survival. PD-L1 expression in >5% of tumour cells was heterogeneous between primary and metastatic tumours in 13 cases (34.2%). PD-L1 expression is common in HNcSCC supporting the rationale for a clinical trial of PD-1/PD-L1 inhibitors. PD-L1 expression in tumour cells or TILs predicts longer disease free survival and demonstrates temperospatial heterogeneity.

Tumor Suppressor microRNAs Contribute to the Regulation of PD-L1 Expression in Malignant Pleural Mesothelioma.

INTRODUCTION: The upregulation of programmed death ligand 1 (PD-L1) is found in many cancers and contributes to evasion of the host's immune defense. In malignant pleural mesothelioma (MPM), PD-L1 expression is associated with the nonepithelioid histological subtype and poor prognosis, but the pathways involved in control of PD-L1 expression in MPM are poorly understood. To address one possible means of PD-L1 regulation we investigated the relationship between dysregulated microRNA levels and PD-L1 expression. METHODS: PD-L1 expression was analyzed by immunohistochemistry in tissue microarrays prepared from samples from patients undergoing an operation (pleurectomy with or without decortication). MicroRNA expression was analyzed by reverse-transcriptase quantitative polymerase chain reaction. Regulation of PD-L1 expression in cell lines was assessed after transfection with microRNA mimics and small interfering RNAs. Interaction between microRNAs and PD-L1 was analyzed by using argonaute-2 immunoprecipitation and a luciferase reporter assay. RESULTS: In a series of 72 patients with MPM, 18 (25%) had positive PD-L1 staining, and this was more common in patients with the nonepithelioid subtype (p = 0.01). PD-L1 expression was associated with poor survival (median overall survival 4.0 versus 9.2 months with positive versus negative PD-L1 expression [p < 0.001]), and in multivariate analyses, PD-L1 expression remained a significant adverse prognostic indicator (hazard ratio = 2.2, 95% confidence interval: 1.2-4.1, p < 0.01). In the same patient series, PD-L1 expression was also associated with downregulation of microRNAs previously shown to have tumor suppressor activity in MPM. The median microRNA expression levels of miR-15b, miR-16, miR-193a-3p, miR-195, and miR-200c were significantly lower in the PD-L1-positive samples. Transfecting MPM cell lines with mimics corresponding to miR-15a and miR-16, both of which are predicted to target PD-L1, led to downregulation of PD-L1 mRNA and protein. In addition, miR-193a-3p, with an alternative G-U-containing target site, also caused PD-L1 downregulation. CONCLUSIONS: Together, these data suggest that tumor suppressor microRNAs contribute to the regulation of PD-L1 expression in MPM.

p16 expression independent of human papillomavirus is associated with lower stage and longer disease-free survival in oral cavity squamous cell carcinoma.

There is limited information regarding the incidence of p16 expression, its association with human papillomavirus (HPV) and prognosis in oral cavity squamous cell carcinoma (OSCC). The role of p16 in OSCC is evaluated in 215 cases using tissue microarrays (TMAs). p16 immunohistochemistry and HPV in situ hybridisation were performed on TMAs following histopathology review of 215 patients with OSCC in the Sydney Head and Neck Cancer Institute database. Thirty-seven (17.2%) cases showed p16 expression without association with HPV. p16 expression significantly decreased with increasing pT category (p=0.002). p16 expression was associated with longer disease-specific survival on univariable analysis (p=0.044) but not on multivariable analysis adjusting for depth of invasion. Amongst patients receiving adjuvant radiotherapy, patients with p16 expression had significantly longer disease-free and overall survival. p16 expression was seen in early stage OSCCs and was associated with better survival following surgery and radiotherapy. While not an independent predictor of survival, p16 may mediate its effects by contributing to reduced proliferative capacity, leading to smaller tumour size and lower invasive potential.

Primary and Metastatic Cutaneous Melanomas Express ALK Through Alternative Transcriptional Initiation.

A number of common driver mutations have been identified in melanoma, but other genetic or epigenetic aberrations are also likely to play a role in the pathogenesis of melanoma and present potential therapeutic targets. Translocations of the anaplastic lymphoma kinase (ALK), for example, have been reported in spitzoid melanocytic neoplasms leading to kinase-fusion proteins that result in immunohistochemically detectable ALK expression. In this study, we sought to determine whether ALK was also expressed in nonspitzoid primary and metastatic cutaneous melanomas. ALK immunohistochemistry was performed on 603 melanomas (303 primary and 300 metastatic tumors) from 600 patients. ALK immunohistochemistry expression was identified in 7 primary and 9 metastatic tumors. In 5 of 7 primary tumors and in 6 of 9 metastatic lesions, the majority of tumor cells were immunoreactive for ALK. In the other 2 primary and 3 metastatic lesions, positive staining was identified in less than half of the tumor cells. ALK positivity was found in the presence or absence of BRAF or NRAS mutations. In contrast to prior observations with ALK-positive Spitz tumors, none of the ALK-positive melanomas harbored a translocation. Instead, the ALK-positive melanomas predominantly expressed the recently described ALK isoform, ALK, which lacks the extracellular and transmembrane domains of wild-type ALK, consists primarily of the intracellular tyrosine kinase domain, and originates from an alternative transcriptional initiation site within the ALK gene. The findings are clinically relevant as patients with metastatic melanoma who have ALK expression may potentially benefit from treatment with ALK kinase inhibitors.

Programmed cell death-ligand 1 expression in oral squamous cell carcinoma is associated with an inflammatory phenotype.

Phase 2 clinical trials utilising novel anti-PD1/PD-L1 antibodies are being conducted in oral cavity squamous cell carcinoma (OSCC) patients. However, data regarding PD-L1 expression in OSCC is limited. The aim of this study was to characterise the PD-L1 immunohistochemical expression in OSCC and its association with clinicopathological factors. Clinicopathological review of 217 patients with OSCC was performed, including quantifying tumour-infiltrating lymphocytes. Immunohistochemistry with PD-L1, CD4 and CD8 was performed. Forty (18.3%) cases showed PD-L1 expression. Expression was significantly more frequent in females (p=0.013), tongue/buccal mucosal SCCs (p=0.05), and in tumours with a high lymphocytic infiltrate (p>0.001). Intratumoural heterogeneity of PD-L1 expression was observed in 30% of the cases. PD-L1 expression was not significantly associated with disease-free (p=0.82) or overall survival (p=0.93). PD-L1 expression occurred in a significant minority of OSCC and can be heterogeneous. Frequent PD-L1 expression in OSCCs in females and in tumours with high lymphocytic infiltrate may assist in the selection of patients who may respond to anti-PD1/PD-L1 therapies.

Diagnostic and prognostic utility of Mastermind-like 2 (MAML2) gene rearrangement detection by fluorescent in situ hybridization (FISH) in mucoepidermoid carcinoma of the salivary glands.

OBJECTIVE: Mucoepidermoid carcinoma (MEC) is the most common salivary gland malignancy, with a proportion harboring MAML2 rearrangement. This study evaluates the diagnostic and prognostic utility of MAML2 rearrangement in MEC. STUDY DESIGN: Salivary gland malignancies at a single institution (1989-2014) were reviewed to identify MECs. Histopathologic evaluation, immunohistochemistry, and fluorescent in situ hybridization (FISH) were performed. RESULTS: Forty-one cases of MEC were identified, with mean age of 47 years and mean tumor size of 21 mm. Seven locoregional recurrences and five MEC-related deaths were seen over a 22-year follow-up period. Thirty-eight cases were suitable for FISH, and 31 (82%) cases were positive for MAML2 rearrangement, including the oncocytic and clear cell variants of MEC. FISH was negative in the morphologic mimics of MEC. MAML2 rearrangement was significantly associated with longer survival. CONCLUSIONS: MAML2 rearrangement is common and specific for MEC, which makes it a useful diagnostic tool. MAML2 rearrangement also predicts a favorable prognosis.

Salivary duct carcinoma: Clinicopathologic features, morphologic spectrum, and somatic mutations.

BACKGROUND: Accurate diagnosis of salivary duct carcinoma requires a high index of suspicion and clinicopathologic correlation. Hallmark genetic changes that may provide novel therapeutic options are being explored. METHODS: One hundred ninety salivary gland malignancies at Royal Prince Alfred Hospital (from 1989-2014) were reviewed. Human epidermal growth factor receptor 2 (HER2) and androgen receptor status were determined along with multigene profiling. RESULTS: Twenty-three salivary duct carcinomas were identified, predominantly in men in their fifth to ninth decades of life. Facial nerve palsy (12%) and cervical lymph node metastases (82%) were present, and 96% received postoperative adjuvant therapy. Histologically, the tumors resembled high-grade invasive and in situ ductal carcinoma of the breast. Micropapillary, papillary, sarcomatoid, oncocytic, and mucinous variants were seen. The tumors showed androgen receptor (70%), HER2 amplification (30%), and HRAS, AKT1, PIK3CA, and NRAS mutations (22%; cumulative). The 5-year disease-free survival was 36%. CONCLUSION: Salivary duct carcinoma demonstrates a wide histopathologic spectrum. Treatment strategies need to take androgen receptor, HER2 amplification, and PIK3CA mutation into account. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1838-E1847, 2016.

Mammary analogue secretory carcinoma: an evaluation of its clinicopathological and genetic characteristics.

Mammary analogue secretory carcinoma (MASC) is a recently described salivary gland malignancy. We evaluate the clinicopathological characteristics and long-term clinical behaviour of MASCs. A total of 190 primary salivary gland malignancies at a single institution were reviewed along with relevant immunohistochemical and fluorescent in situ hybridisation (FISH) studies to identify MASCs. Nine MASCs were identified predominantly in the parotid with an equal incidence in men and women and mean age of 36 years. The tumour size ranged from 14 to 50 mm (mean 22 mm). MASCs were composed of monotonous cells with vacuolated eosinophilic cytoplasm and a small nucleus with a distinctive nucleolus. All cases showed immunoreactivity with S-100, MUC4, CK7 and mammoglobin, and lacked immunoreactivity with DOG1, p63, CK5/6 and calponin. ETV6 rearrangement was seen in all cases. No mutations were identified using the OncoCarta Panel v1.0 Kit. Follow up was available for 0.4 to 22 years (median 4 years). Intraparotid lymph node involvement and local recurrence were seen in one patient each. There were no distant metastases. MASCs have specific histopathological features and immunohistochemical profile that distinguish them from their mimics. FISH plays a confirmatory role. An indolent long-term clinical course was observed in this cohort despite involvement of intraparotid lymph node and microscopically involved/close margins.

BRAF mutations in non-small cell lung cancer.

BACKGROUND: BRAF is a proto-oncogene encoding a serine/threonine protein kinase which promotes cell proliferation and survival. BRAF mutations are commonly seen in melanoma and papillary thyroid carcinoma. We aimed to investigate the prevalence and clinicopathological features of BRAF mutations in non-small cell lung cancer (NSCLC) cases submitted for routine mutation testing at our institution. METHODS: Mutation analysis for BRAF, EGFR and KRAS was performed using Sequenom MassARRAY platform with OncoCarta panel v1.0. Pathological features were reviewed and immunohistochemistry for BRAF V600E was also performed. RESULTS: Seven out of 273 cases (2.6%) had BRAF mutations (three males and four females, median age 70 years, all smokers), with six adenocarcinomas and one NSCLC, not otherwise specified (NOS). All had wild-type EGFR and KRAS. The identified BRAF mutations were V600E (4/7, 58%), K601N, L597Q and G469V. BRAF V600E immunohistochemistry was positive in two cases with V600E and negative in one case with K601N (tissue available in three cases only). No significant difference in age or gender was found (BRAF mutant vs. wild-type). CONCLUSIONS: BRAF mutations occur in a small proportion of NSCLC that lack other driver mutations. The clinicopathological profile differs from that of EGFR mutant tumours. The potential benefits of BRAF-inhibitors should be investigated.

Concordant BRAFV600E mutation status in primary melanomas and associated naevi: implications for mutation testing of primary melanomas.

There is concern that BRAF mutant naevus cells admixed with melanoma cells could cause false positive mutation tests in BRAF wild-type melanomas. We sought to assess the frequency of BRAF(V600E) mutations in primary melanomas arising with/without associated naevi and determine BRAF(V600E) concordance between melanomas and associated naevi. Formalin fixed, paraffin embedded (FFPE) tissue from 57 patients with primary melanomas with/without associated naevi was immunohistochemically stained to detect BRAF(V600E) mutation. In a subset of patients (n = 29), molecular mutation testing was also carried out using a panel of 238 known genetic variants. Of the primary melanomas with an associated naevus (n = 29), 55% were BRAF(V600E) mutant with 100% concordance between the melanoma and associated naevus. In contrast, only 21% of the primary melanomas unassociated with naevi were BRAF(V600E) mutant (p = 0.009).Our results suggest that melanomas with associated naevi have a higher frequency of BRAF(V600E) mutations than melanomas unassociated with naevi. Furthermore, melanomas and their associated naevi were concordant in BRAF(V600E) status, which suggests that false positive mutation tests occurring as a consequence of admixed BRAF mutant naevus cells in BRAF wild-type primary melanomas are unlikely to be a problem in clinical practice. The findings have important implications for adjuvant clinical trials of targeted therapies.

Intrapatient homogeneity of BRAFV600E expression in melanoma.

Concern regarding the presence of intertumoral heterogeneity of BRAF mutation status in patients with metastatic melanoma has led to uncertainty surrounding which specimens should preferentially undergo BRAF testing. We sought to examine the extent of intrapatient heterogeneity of BRAF(V600E) protein expression in patients with multiple tumors. Sixty-four patients with 171 tumors at various stages of disease progression had tumor BRAF(V600E) protein expression immunohistochemically (IHC) assessed using the BRAF(V600E) mutant-specific antibody VE1. Melanoma sections were examined for staining intensity (score 0 to 3), the presence of intratumoral heterogeneity, and concordance with molecular BRAF genotype. Intrapatient, intertumoral heterogeneity of BRAF(V600E) expression was also assessed by comparing VE1 staining on different tumors within the same patient. All specimens from 64 patients displayed complete intertumoral homogeneity of BRAF(V600E) expression status, and all tumors had concordant molecular and IHC BRAF status. Only 1 patient demonstrated >1 level of staining intensity heterogeneity between specimens. Intratumoral heterogeneity of staining intensity was not observed in any specimen. IHC-measured BRAF(V600E) protein expression displays complete intertumoral homogeneity, minimal intertumoral intensity heterogeneity, and no intratumoral heterogeneity in metastatic melanoma patients in various stages of disease progression. Our results suggest that, provided there is adequate quantity of viable tumor cells and minimal admixture of nontumor cells, testing any melanoma sample from a patient with metastatic disease will accurately determine BRAF status for treatment planning.