Melanoma Brain Metastasis: Mechanisms, Models, and Medicine

The development of brain metastases in patients with advanced stage melanoma is common, but the molecular mechanisms responsible for their development are poorly understood. Melanoma brain metastases cause significant morbidity and mortality and confer a poor prognosis; traditional therapies including whole brain radiation, stereotactic radiotherapy, or chemotherapy yield only modest increases in overall survival (OS) for these patients. While recently approved therapies have significantly improved OS in melanoma patients, only a small number of studies have investigated their efficacy in patients with brain metastases. Preliminary data suggest that some responses have been observed in intracranial lesions, which has sparked new clinical trials designed to evaluate the efficacy in melanoma patients with brain metastases. Simultaneously, recent advances in our understanding of the mechanisms of melanoma cell dissemination to the brain have revealed novel and potentially therapeutic targets. In this review, we provide an overview of newly discovered mechanisms of melanoma spread to the brain, discuss preclinical models that are being used to further our understanding of this deadly disease and provide an update of the current clinical trials for melanoma patients with brain metastases.

Immunotherapy in melanoma: Recent advances and future directions

Malignant melanoma contributes the majority of skin cancer related deaths and shows an increasing incidence in the past years. Despite all efforts of early diagnosis, metastatic melanoma still has a poor prognosis and remains a challenge for treating physicians. In recent years, improved knowledge of the pathophysiology and a better understanding of the role of the immune system in tumour control have led to the development and approval of several immunotherapies. Monoclonal antibodies against different immune checkpoints have been revolutionizing the treatment of metastatic and unresectable melanoma. Ipilimumab, a monoclonal antibody against the cytotoxic T-lymphocyte antigen 4 (CTLA-4) as well as nivolumab and pembrolizumab which target the programmed cell death protein 1 (PD-1) have been shown to prolong overall survival in patients with advanced melanoma. The latter substances seem to have an increased response rate and more tolerable safety profile compared to ipilimumab. The combination of a CTLA-4 and a PD-1 inhibitor seems to be superior to the monotherapies, especially in patients with PD-L1 negative tumours. Checkpoint inhibitors are currently being tested in the adjuvant setting with initial data for ipilimumab suggesting efficacy in this context. Talimogene laherparepvec (TVEC) is the first oncolytic virus approved in the therapy of metastatic melanoma offering a treatment option especially for patients with limited disease. In this review, data on these recently developed and approved immunotherapies are presented. However, further studies are necessary to determine the optimal duration, sequencing and combinations of immunotherapies to further improve the outcome of patients with advanced melanoma.

Altered Morphology and Immunohistochemical Characteristics in Metastatic Malignant Melanoma After Therapy With Vemurafenib

Metastatic melanoma is traditionally diagnosed using classic morphologic features in addition to immunohistochemical studies. The authors report a case of metastatic malignant melanoma where both morphology and immunohistochemistry were altered after treatment. This 51-year-old patient presented with metastatic melanoma to the brain and axilla. Initially, both metastases showed classic morphology and diffuse staining with the pan-melanoma antibody cocktail. This cocktail is a combination of 3 antibodies commonly used to diagnose melanocytic neoplasms: Melan-A (MART-1), tyrosinase, and HMB-45. In combination, the cocktail is highly sensitive for detecting melanocytic neoplasms and is commonly used to diagnose metastatic melanoma. Her tumor was positive for the BRAF 1799T>A (V600E) mutation, and she was treated with BRAF inhibitor therapy (vemurafenib). However, the axillary tumor recurred after treatment with vemurafenib. The recurrent tumor showed a markedly different morphology and complete loss of staining with the pan-melanoma antibody cocktail. This loss of staining accompanied by the change in morphology was an observation not previously documented after therapy with vemurafenib. This case demonstrates a potential pitfall in the diagnosis of metastatic or recurrent malignant melanoma.

A comparison of immunohistochemical and molecular methods used for analyzing the BRAF V600E gene mutation in malignant melanoma in Taiwan

AIMS

The BRAF V600 mutation has been shown to be clinically meaningful in terms of both the prognosis and sensitivity of BRAF inhibitors in patients with metastatic melanoma. Recently, a BRAF V600E mutation-specific antibody, VE1, was generated for the detection of tumors bearing BRAF V600E mutations. To determine the clinical value of immunohistochemical testing, we compared the prevalence of mutant BRAF detected by VE1 with direct sequencing results.

METHODS

Paraffin-embedded, formalin-fixed melanoma biopsies were analyzed for the BRAF mutation status by immunohistochemistry with the VE1 antibody. Sanger sequencing was applied to verify the immunohistochemical results.

RESULTS

A total of 73 melanoma cases with tumor samples from primary lymph nodes and metastatic sites were selected for this study. Direct sequencing demonstrated that 18 of 73 cases (24.6%) harbored the BRAF V600 mutation: 17 with V600E and one with V600K. All 18 tumors shown to harbor the BRAF V600E/K mutations were VE1-positive. One additional case was false-positive for VE1. The sensitivity and specificity of VE1 was 100% (18/18) and 98% (54/55), respectively. The overall concordance between the immunohistochemical method and direct sequencing was excellent (98.6%).

CONCLUSIONS

Our findings demonstrate that immunohistochemical analysis using VE1 constitutes a highly sensitive test for the detection of BRAF mutations and suggest that this cost-effective method is suitable as a rapid diagnostic approach complementary to molecular testing.

RICTOR involvement in the PI3K/AKT pathway regulation in melanocytes and melanoma

Several studies have highlighted the importance of the PI3K pathway in melanocytes and its frequent over-activation in melanoma. However, little is known about regulation of the PI3K pathway in melanocytic cells. We showed that normal human melanocytes are less sensitive to selective PI3K or mTOR inhibitors than to dual PI3K/mTOR inhibitors. The resistance to PI3K inhibitor was due to a rapid AKT reactivation limiting the inhibitor effect on proliferation. Reactivation of AKT was linked to a feedback mechanism involving the mTORC2 complex and in particular its scaffold protein RICTOR. RICTOR overexpression in melanocytes disrupted the negative feedback, activated the AKT pathway and stimulated clonogenicity highlighting the importance of this feedback to restrict melanocyte proliferation. We found that the RICTOR locus is frequently amplified and overexpressed in melanoma and that RICTOR over-expression in NRAS-transformed melanocytes stimulates their clonogenicity, demonstrating that RICTOR amplification can cooperate with NRAS mutation to stimulate melanoma proliferation. These results show that RICTOR plays a central role in PI3K pathway negative feedback in melanocytes and that its deregulation could be involved in melanoma development.

Diagnosis and treatment of melanoma. European consensus-based interdisciplinary guideline - Update 2016

Cutaneous melanoma (CM) is potentially the most dangerous form of skin tumour and causes 90% of skin cancer mortality. A unique collaboration of multi-disciplinary experts from the European Dermatology Forum, the European Association of Dermato-Oncology and the European Organisation of Research and Treatment of Cancer was formed to make recommendations on CM diagnosis and treatment, based on systematic literature reviews and the experts' experience. Diagnosis is made clinically using dermoscopy and staging is based upon the AJCC system. CMs are excised with 1-2 cm safety margins. Sentinel lymph node dissection is routinely offered as a staging procedure in patients with tumours >1 mm in thickness, although there is as yet no clear survival benefit for this approach. Interferon-α treatment may be offered to patients with stage II and III melanoma as an adjuvant therapy, as this treatment increases at least the disease-free survival and less clear the overall survival (OS) time. The treatment is however associated with significant toxicity. In distant metastasis, all options of surgical therapy have to be considered thoroughly. In the absence of surgical options, systemic treatment is indicated. For first-line treatment particularly in BRAF wild-type patients, immunotherapy with PD-1 antibodies alone or in combination with CTLA-4 antibodies should be considered. BRAF inhibitors like dabrafenib and vemurafenib in combination with the MEK inhibitors trametinib and cobimetinib for BRAF mutated patients should be offered as first or second line treatment. Therapeutic decisions in stage IV patients should be primarily made by an interdisciplinary oncology team ('Tumour Board').

Targeting the mitogen-activated protein kinase pathway in low-grade serous carcinoma of the ovary

Until recently, there has been little change in the management of epithelial ovarian cancer with the majority of women receiving identical systemic therapy, regardless of histological subtype. The heterogeneity of epithelial ovarian cancer is now well established, with distinct subtypes characterized by specific molecular alterations and patterns of clinical behavior. Low-grade serous carcinoma is a rare subtype associated with an indolent biological behavior and inherent resistance to chemotherapy. The mitogen-activated protein kinase pathway plays a prominent role in the pathogenesis of low-grade serous carcinoma, and provides an attractive target for novel therapeutic agents. Selumetinib, a MEK1/2 inhibitor, demonstrates promising efficacy in women with relapsed low-grade serous carcinoma, and further trials of MEK-inhibition are underway. Translational research will be essential to identify predictive biomarkers for this treatment approach.

Individualized strategies to target specific mechanisms of disease in malignant melanoma patients displaying unique mutational signatures

Targeted treatment of advanced melanoma could benefit from the precise molecular characterization of melanoma samples. Using a melanoma-specific selection of 217 genes, we performed targeted deep sequencing of a series of biopsies, from advanced melanoma cases, with a Breslow index of ≥4 mm, and/or with a loco-regional infiltration in lymph nodes or presenting distant metastasis, as well of a collection of human cell lines. This approach detected 3–4 mutations per case, constituting unique mutational signatures associated with specific inhibitor sensitivity. Functionally, case-specific combinations of inhibitors that simultaneously targeted MAPK-dependent and MAPK-independent mechanisms were most effective at inhibiting melanoma growth, against each specific mutational background. These observations were challenged by characterizing a freshly resected biopsy from a metastatic lesion located in the skin and soft tissue and by testing its associated therapy ex vivo and in vivo using melanocytes and patient-derived xenografted mice, respectively.

The results show that upon mutational characterization of advanced melanoma patients, specific mutational profiles can be used for selecting drugs that simultaneously target several deregulated genes/pathways involved in tumor generation or progression.

BRAF and Epithelial-Mesenchymal Transition: Lessons From Papillary Thyroid Carcinoma and Primary Cutaneous Melanoma

The increased prevalence of BRAF mutations in thyroid carcinoma and primary cutaneous melanoma (PCM) hint that dysregulation of BRAF might contribute to the noted association between PCM and thyroid carcinoma. A recent study evaluating the rate of BRAFV600E mutations among patients who had been diagnosed with primary papillary thyroid carcinoma (PTC) and PCM showed that patients with either PCM or PTC were at an increased risk of developing the other as a second primary malignant neoplasm. Furthermore, the authors noted that samples from patients suffering from both malignancies exhibited a higher rate of incidence of the BRAFV600E mutation, compared with patients not suffering from both malignancies. These studies support the hypothesis that the pathogenesis of these 2 malignancies might share a conserved molecular pattern associated with dysregulation of the BRAF protein. One mechanism through which BRAF might contribute to PCM and thyroid carcinoma progression is through induction of epithelial-mesenchymal transition (EMT). Specifically, the Snail/E-cadherin axis has been demonstrated as a pathway dysregulated by BRAF, leading to EMT in both malignancies. Our analysis focuses on the results of these recent investigations, and through a review of select molecules relevant to EMT, looks to provide a context by which to better understand the relevance and role of stromal-parenchymal signaling and the BRAF mutation in the pathogenesis of PTC and PCM.

Antitumor Activity of BRAF Inhibitor and IFNα Combination in BRAF-Mutant Melanoma

BACKGROUND

BRAF(V600E)-mediated MAPK pathway activation is associated in melanoma cells with IFNAR1 downregulation. IFNAR1 regulates melanoma cell sensitivity to IFNα, a cytokine used for the adjuvant treatment of melanoma. These findings and the limited therapeutic efficacy of BRAF-I prompted us to examine whether the efficacy of IFNα therapy of BRAF(V600E) melanoma can be increased by its combination with BRAF-I.

METHODS

BRAF/NRAS genotype, ERK activation, IFNAR1, and HLA class I expression were tested in 60 primary melanoma tumors from treatment-naive patients. The effect of BRAF-I on IFNAR1 expression was assessed in three melanoma cell lines and in four biopsies of BRAF(V600E) metastases. The antiproliferative, pro-apoptotic and immunomodulatory activity of BRAF-I and IFNα combination was tested in vitro and in vivo utilizing three melanoma cell lines, HLA class I-MA peptide complex-specific T-cells and immunodeficient mice (5 per group for survival and 10 per group for tumor growth inhibition). All statistical tests were two-sided. Differences were considered statistically significant when the P value was less than .05.

RESULTS

The IFNAR1 level was statistically significantly (P < .001) lower in BRAF(V600E) primary melanoma tumors than in BRAF wild-type tumors. IFNAR1 downregulation was reversed by BRAF-I treatment in the three melanoma cell lines (P ≤ .02) and in three out of four metastases. The IFNAR1 level in the melanoma tumors analyzed was increased as early as 10 to 14 days following the beginning of the treatment. These changes were associated with: 1) an increased susceptibility in vitro of melanoma cells to the antiproliferative (P ≤ .04), pro-apoptotic (P ≤ .009) and immunomodulatory activity, including upregulation of HLA class I antigen APM component (P ≤ .04) and MA expression as well as recognition by cognate T-cells (P < .001), of BRAF-I and IFNα combination and 2) an increased survival (P < .001) and inhibition of tumor growth of melanoma cells (P < .001) in vivo by BRAF-I and IFNα combination.

CONCLUSIONS

The described results provide a strong rationale for the clinical trials implemented in BRAF(V600E) melanoma patients with BRAF-I and IFNα combination.

Malignant Melanoma of Vulva and Vagina: A Histomorphological Review and Mutation Analysis--A Single-Center Study

OBJECTIVES

The aim of this work was to determine molecular characteristics and specifically, the frequency of BRAF, C-KIT, and NRAS mutations in vulvar and vaginal melanomas.

METHODS

A retrospective review of all cases of vulvar and vaginal melanoma between 2002 and 2013 was performed. We reviewed the clinical and histological characteristics of all cases and performed genotyping studies on cases that had tissue available for the study, using next-generation sequencing.

RESULTS

We identified 33 vulvar and 11 vaginal melanomas in women with mean ages 58 and 61 years, respectively. Next-generation sequencing analysis on 20 cases (15 vulvar and 5 vaginal) identified a BRAF mutation in 7.6%, C-KIT mutation in 27.6%, NRAS mutation in 27.6%, and TP53 mutation in 7.6% of the vulvar cases. We detected only a single TP53 mutation in the vaginal cases. We did not identify any statistically significant relationship between the mutation status and patients' outcome, depth of invasion, ulceration, stage at presentation, or lymph node metastasis.

CONCLUSIONS

BRAF mutations are infrequent, whereas C-KIT and NRAS mutations are seen with higher frequency in vulvar melanomas than melanomas of other sites. These mutations can be considered as potential therapeutic targets in patients harboring them. Further studies are necessary to increase our understanding of mutational events occurring in melanoma of the lower female genital tract and their relationship with clinical parameters/outcome.

A combination of high dose rate (10X FFF/2400 MU/min/10 MV X-rays) and total low dose (0.5 Gy) induces a higher rate of apoptosis in melanoma cells in vitro and superior preservation of normal melanocytes

The aim of this study was to determine the apoptotic effects, toxicity, and radiosensitization of total low dose irradiation delivered at a high dose rate in vitro to melanoma cells, normal human epidermal melanocytes (HEM), or normal human dermal fibroblasts (HDF) and to study the effect of mitochondrial inhibition in combination with radiation to enhance apoptosis in melanoma cells. Cells irradiated using 10X flattening filter-free (FFF) 10 MV X-rays at a dose rate of 400 or 2400 MU/min and a total dose of 0.25–8 Gy were analyzed by cell/colony counting, MitoTracker, MTT, and DNA-damage assays, as well as by quantitative real-time reverse transcriptase PCR in the presence or absence of mitochondrial respiration inhibitors. A dose rate of 2400 MU/min killed on average five-fold more melanoma cells than a dose rate 400 MU/min at a total dose of 0.5 Gy and preserved 80% survival of HEM and 90% survival of HDF. Increased apoptosis at the 2400 MU/min dose rate is mediated by greater DNA damage, reduced cell proliferation, upregulation of apoptotic genes, and downregulation of cell cycle genes. HEM and HDF were relatively unharmed at 2400 MU/min. Radiation induced upregulation of mitochondrial respiration in both normal and cancer cells, and blocking the respiration with inhibitors enhanced apoptosis only in melanoma cells. A high dose rate with a low total dose (2400 MU/min, 0.5 Gy/10X FFF 10 MV X-rays) enhances radiosensitivity of melanoma cells while reducing radiotoxicity toward HEM and HDF. Selective cytotoxicity of melanoma cells is increased by blocking mitochondrial respiration.

Estimating healthcare resource use associated with the treatment of metastatic melanoma in eight countries

Objectives Studies reporting healthcare resourse use (HRU) for melanoma, one of the most costly cancers to treat, are limited. Using consistent, robust methodology, this study estimated HRU associated with the treatment of metastatic melanoma in eight countries. Methods Using published literature and clinician input, treatment phases were identified: active systemic treatment (pre-progression); disease progression; best supportive care (BSC)/palliative care; and terminal care. HRU elements were identified for each phase and estimates of the magnitude and frequency of use in clinical practice were obtained through country-specific Delphi panels, comprising healthcare professionals with experience in oncology (n = 8). Results Medical oncologists are the key care providers for patients with metastatic melanoma, although in Germany dermato-oncologists also lead care. During the active systemic treatment phase, each patient was estimated to require 0.83-2 consultations with a medical oncologist/month across countries; the median number of such assessments in 3 months was highest in Canada (range = 3.5-5) and lowest in France, the Netherlands and Spain (1). Resource use during the disease progression phase was intensive and similar across countries: all patients were estimated to consult with medical oncologists and 10-40% with a radiation oncologist; up to 40% were estimated to require a brain MRI scan. During the BSC/palliative care phase, all patients were estimated to consult with medical oncologists, and most to consult with a primary care physician (40-100%). Limitations Panelists were from centers of excellence, thus results may not reflect care within smaller hospitals; data obtained from experts may be less variable than data from broader clinical practice. Treatments for metastatic melanoma are continually emerging, thus some elements of our work could be superseded. Conclusions HRU estimates were substantial and varied across countries for some resources. These data could be used with country-specific costs to elucidate costs for the management of metastatic melanoma.

Molecular characterization of a selected cohort of patients affected by pulmonary metastases of malignant melanoma: Hints from BRAF, NRAS and EGFR evaluation

Background

Melanoma is highly curable in early stages but holds devastating consequences in advanced phases with a median survival of 6–10 months. Lungs are a common metastasis target, but despite this, limited data are available on the molecular status of pulmonary lesions.

Materials and Methods

25 patients with surgically resected melanoma lung metastases were screened for BRAF, NRAS, CKIT and EGFR alterations. The results were correlated with time to lung metastasis (TLM), relapse-free survival after metastasectomy (RFS) and overall survival (OS).

Results

BRAF or NRAS were mutated in 52% and 20% of cases while CKIT was unaffected. Chromosome 7 polysomy was detected in 47% of cases with 17.5% showing EGFR amplification and concomitant BRAF mutation. NRAS mutated patients developed LM within 5 yrs from primary melanoma with larger lesions compared with BRAF (mean diameter 3.3 ± 2.2cm vs 1.9 ± 1.1cm, p = 0.2). NRAS was also associated with a shorter median RFS and OS after metastasectomy. Moreover, Cox regression analysis revealed that NRAS mutation was the only predictive factor of shorter survival from primary melanoma (p = 0.039, OR = 5.5 (1.1–27.6)).

Conclusions

Molecular characterization identifies advanced melanoma subgroups with distinct prognosis and therapeutic options. The presence of NRAS mutation was associated to a worse disease evolution.

BRAF V600E mutation and BRAF kinase inhibitors in conjunction with stereotactic radiosurgery for intracranial melanoma metastases

OBJECTIVE Recent advancements in molecular biology have identified the BRAF mutation as a common mutation in melanoma. The wide use of BRAF kinase inhibitor ( BRAFi) in patients with metastatic melanoma has been established. The objective of this study was to examine the impact of BRAF mutation status and use of BRAFi in conjunction with stereotactic radiosurgery (SRS). METHODS This was a single-center retrospective study. Patient's charts and electronic records were reviewed for date of diagnosis of primary malignancy, BRAF mutation status, chemotherapies used, date of the diagnosis of CNS metastases, date of SRS, survival, local tumor control after SRS, and adverse events. Patients were divided into 3 groups: Group A, those with mutant BRAF without BRAFi treatment (13 patients); Group B, those with mutant BRAF with BRAFi treatment (17 patients); and Group C, those with wild-type BRAF (35 patients). Within a cohort of 65 patients with the known BRAF mutation status and treated with SRS between 2010 and 2014, 436 individual brain metastases (BMs) were identified. Kaplan-Meier methodology was then used to compare survival based on each binary parameter. RESULTS Median survival times after the diagnosis of melanoma BM and after SRS were favorable in patients with a BRAF mutation and treated with SRS in conjunction with BRAFi (Group B) compared with the patients with wild-type BRAF (Group C, 23 vs 8 months and 13 vs 5 months, respectively; p < 0.01, log-rank test). SRS provided a local tumor control rate of 89.4% in the entire cohort of patients. Furthermore, the local control rate was improved in the patients treated with SRS in conjunction with BRAFi (Group B) compared with patients with wild-type (Group C) or with BRAF mutation but no BRAFi (Group A) as an adjunct treatment for BMs. CONCLUSIONS BRAF mutation status appears to play an important role as a potent prognostic factor in patients harboring melanoma BM. BRAFi in conjunction with SRS may benefit this group of patients in terms of BM survival and SRS with an acceptable safety profile.

Oncogenic BRAF-Mediated Melanoma Cell Invasion

Melanoma patients with oncogenic BRAF(V600E) mutation have poor prognoses. While the role of BRAF(V600E) in tumorigenesis is well established, its involvement in metastasis that is clinically observed in melanoma patients remains a topic of debate. Here, we show that BRAF(V600E) melanoma cells have extensive invasion activity as assayed by the generation of F-actin and cortactin foci that mediate membrane protrusion, and degradation of the extracellular matrix (ECM). Inhibition of BRAF(V600E) blocks melanoma cell invasion. In a BRAF(V600E)-driven murine melanoma model or in patients' tumor biopsies, cortactin foci decrease upon inhibitor treatment. In addition, genome-wide expression analysis shows that a number of invadopodia-related genes are downregulated after BRAF(V600E) inhibition. Mechanistically, BRAF(V600E) induces phosphorylation of cortactin and the exocyst subunit Exo70 through ERK, which regulates actin dynamics and matrix metalloprotease secretion, respectively. Our results provide support for the role of BRAF(V600E) in metastasis and suggest that inhibiting invasion is a potential therapeutic strategy against melanoma.

TLR7 Gln11Leu single nucleotide polymorphism and susceptibility to cutaneous melanoma

Cutaneous melanoma is a life-threatening skin cancer. Its incidence is rapidly increasing, and early diagnosis is the main factor able to improve its poor prognosis. Toll-like receptors (TLRs) are transmembrane glycoproteins that recognize pathogen- and damage-associated molecular patterns, against which TLRs activate the innate immune response and initiate the adaptive immune response. Genetic variations of these receptors may alter the immune system, and are involved in evolution and susceptibility to various diseases, including cancer. The aim of the present study was to evaluate whether the presence of TLR7 glutamine (Gln) 11 leucine (Leu) polymorphism confers an increased susceptibility to cutaneous melanoma. For that purpose, a case-control study was performed with 182 melanoma cases and 89 controls. To highlight the possible association between the aforementioned polymorphism and the susceptibility to melanoma, 93 cases of single melanoma and 89 cases of multiple primary melanoma (MPM) were compared in the present study. Since the TLR7 gene is localized on the chromosome X, the allelic frequency of the Gln11Leu polymorphism was analyzed separately in males and females. The distribution of allele frequencies between melanoma cases and controls (P=0.245) and between single melanoma and MPM cases (P=0.482) was not significant. Therefore, the present results do not suggest an association between TLR7 Gln11Leu polymorphism and susceptibility to cutaneous melanoma. Further studies are required to analyze the influence of other TLR polymorphisms on the susceptibility to malignant melanoma and the involvement of innate immunity in this malignancy.

Identification of an Immunogenic Subset of Metastatic Uveal Melanoma

PURPOSE

Uveal melanoma is a rare melanoma variant with no effective therapies once metastases develop. Although durable cancer regression can be achieved in metastatic cutaneous melanoma with immunotherapies that augment naturally existing antitumor T-cell responses, the role of these treatments for metastatic uveal melanoma remains unclear. We sought to define the relative immunogenicity of these two melanoma variants and determine whether endogenous antitumor immune responses exist against uveal melanoma.

EXPERIMENTAL DESIGN

We surgically procured liver metastases from uveal melanoma (n = 16) and cutaneous melanoma (n = 35) patients and compared the attributes of their respective tumor cell populations and their infiltrating T cells (TIL) using clinical radiology, histopathology, immune assays, and whole-exomic sequencing.

RESULTS

Despite having common melanocytic lineage, uveal melanoma and cutaneous melanoma metastases differed in their melanin content, tumor differentiation antigen expression, and somatic mutational profile. Immunologic analysis of TIL cultures expanded from these divergent forms of melanoma revealed cutaneous melanoma TIL were predominantly composed of CD8(+) T cells, whereas uveal melanoma TIL were CD4(+) dominant. Reactivity against autologous tumor was significantly greater in cutaneous melanoma TIL compared with uveal melanoma TIL. However, we identified TIL from a subset of uveal melanoma patients which had robust antitumor reactivity comparable in magnitude with cutaneous melanoma TIL. Interestingly, the absence of melanin pigmentation in the parental tumor strongly correlated with the generation of highly reactive uveal melanoma TIL.

CONCLUSIONS

The discovery of this immunogenic group of uveal melanoma metastases should prompt clinical efforts to determine whether patients who harbor these unique tumors can benefit from immunotherapies that exploit endogenous antitumor T-cell populations. Clin Cancer Res; 22(9); 2237-49. ©2015 AACR.

Combination dabrafenib and trametinib in the management of advanced melanoma with BRAFV600 mutations

INTRODUCTION

In the 40-50% of advanced melanoma patients with tumors harboring BRAF V600E and V600 K mutations, BRAF inhibitors such as dabrafenib are a highly effective treatment. However, most patients develop resistance after several months on treatment. The addition of a MEK inhibitor, such as trametinib, to BRAF inhibition mitigates one key pathway of resistance, further increasing response rates and improving survival.

AREAS COVERED

This article summarizes the mechanism of action of the combination of dabrafenib and trametinib, its evolution through Phase I, II and III clinical trials and discusses its current use in the management of patients with advanced melanoma.

EXPERT OPINION

Combination therapy with dabrafenib and trametinib improves response rate, progression-free survival and overall survival when compared to dabrafenib or vemurafenib alone. The addition of trametinib to dabrafenib changes the adverse event profile, making hyperkeratosis and cutaneous squamous cell carcinomas less common but side effects such as fever and nausea more common. How dabrafenib/trametinib is best sequenced with other effective treatments such as immune checkpoint blockade remains uncertain.

[Malignant head and neck melanoma : Part 1: Diagnosis and histological particularities]

About 15% of all cutaneous melanomas develop in the head and neck region. Mucosal melanomas are rare and represent only 1% of all melanomas, however, most frequently, these are located in the nose, the paranasal sinuses and the oral cavity. Visual diagnosis and reflected-light microscopy are relevant for the evaluation of melanoma-suspect lesions. Histological investigation of resected tumors need special skills of the histopathologist and includes in case of high-risk tumors investigations of mutations in the tumor tissue concerning NRAS, BRAF and KIT. The risk of lymphatic or hematogeneous spread rises with increasing tumor thickness and the presence of further prognostic risk factors such as ulceration of the primary tumor or the presence of mitoses within the tumor.

Quantitative analysis of the BRAF V600E mutation in circulating tumor-derived DNA in melanoma patients using competitive allele-specific TaqMan PCR

BACKGROUND

BRAF ^V600E is a common mutation in melanoma, and BRAF inhibitors are effective in treating of BRAF mutation-positive melanoma. DNA carrying this mutation is released from melanoma cells into the circulation. As such, circulating tumor-derived DNA (ctDNA) in peripheral blood represents a novel biomarker for evaluating tumor features in cancer patients. However, ctDNA is present in the peripheral blood at very low levels, which makes the detection of specific mutations in this DNA a challenge. Competitive allele-specific TaqMan PCR (castPCR), a straightforward commercially available assay, is a sensitive technique for quantitating a small amount of DNA.

METHODS

The level of BRAF ^V600E ctDNA was quantified by castPCR in 26 consecutive plasma samples from six melanoma patients.

RESULTS

The castPCR assay was performed using a mixture of BRAF ^V600E DNA and BRAF ^wild DNA and found to be able to detect BRAF ^V600E at a fractional abundance of ≥0.5 % in 2- to 10-ng samples of genomic DNA. Cell-free DNA was then extracted from peripheral blood samples collected from six patients with melanoma harboring the BRAF ^V600E mutation. BRAF ^V600E ctDNA was detected in three patients, at a fractional abundance of between 1.28 and 58.0 % of total BRAF cell-free DNA. The abundance of BRAF ^V600E ctDNA correlated with tumor burden, as determined by computed tomography imaging. In two cases, an increase in the level of BRAF ^V600E ctDNA preceded exacerbation of clinical symptoms.

CONCLUSION

The castPCR assay can detect and quantitate small amounts of BRAF ^V600E ctDNA in samples containing large amounts of BRAF ^wild cell-free DNA. Thus, we suggest that the castPCR assay is suitable for monitoring ctDNA in the plasma of melanoma patients.

Targeting metastasis

Tumour metastasis, the movement of tumour cells from a primary site to progressively colonize distant organs, is a major contributor to the deaths of cancer patients. Therapeutic goals are the prevention of an initial metastasis in high-risk patients, shrinkage of established lesions and prevention of additional metastases in patients with limited disease. Instead of being autonomous, tumour cells engage in bidirectional interactions with metastatic microenvironments to alter antitumour immunity, the extracellular milieu, genomic stability, survival signalling, chemotherapeutic resistance and proliferative cycles. Can targeting of these interactions significantly improve patient outcomes? In this Review preclinical research, combination therapies and clinical trial designs are re-examined.

BRAF-V600E expression in primary nodular melanoma is associated with aggressive tumour features and reduced survival

BACKGROUND

Around 50% of primary melanomas harbour BRAF mutations, but their prognostic impact has not been clear. Recently, a BRAF-V600E mutation-specific antibody has become available for immunohistochemistry. Here, we investigated for the first time the prognostic impact of BRAF-V600E protein expression in primary melanoma.

METHODS

In a patient series of 248 nodular melanomas, BRAF-V600E and total BRAF expression were assessed by immunohistochemistry using tissue microarray sections of paraffin-embedded archival tissue. Mutation status was assessed by real-time PCR in cases with sufficient tumour tissue (n=191).

RESULTS

Positive BRAF-V600E expression was present in 86 (35%) of the cases, and was significantly associated with increased tumour thickness, presence of tumour ulceration and reduced survival. Further, BRAF-V600E expression was an independent prognostic factor by multivariate analysis, whereas BRAF mutation status was not significant. There was 88% concordance between BRAF-V600E expression and mutation status.

CONCLUSIONS

Our findings indicate that BRAF-V600E expression is a novel prognostic marker in primary melanoma.

Targeting mutant NRAS signaling pathways in melanoma

Cutaneous melanoma is a devastating form of skin cancer and its incidence is increasing faster than any other preventable cancer in the United States. The mutant NRAS subset of melanoma is more aggressive and associated with poorer outcomes compared to non-NRAS mutant melanoma. The aggressive nature and complex molecular signaling conferred by this transformation has evaded clinically effective treatment options. This review examines the major downstream effectors of NRAS relevant in melanoma and the associated advances made in targeted therapies that focus on these effector pathways. We outline the history of MEK inhibition in mutant NRAS melanoma and recent advances with newer MEK inhibitors. Since MEK inhibitors will likely be optimized when combined with other targeted therapies, we focus on recently identified targets that can be used in combination with MEK inhibitors.

SOX5 is involved in balanced MITF regulation in human melanoma cells

Background

Melanoma is a cancer with rising incidence and new therapeutics are needed. For this, it is necessary to understand the molecular mechanisms of melanoma development and progression. Melanoma differs from other cancers by its ability to produce the pigment melanin via melanogenesis; this biosynthesis is essentially regulated by microphthalmia-associated transcription factor (MITF). MITF regulates various processes such as cell cycling and differentiation. MITF shows an ambivalent role, since high levels inhibit cell proliferation and low levels promote invasion. Hence, well-balanced MITF homeostasis is important for the progression and spread of melanoma. Therefore, it is difficult to use MITF itself for targeted therapy, but elucidating its complex regulation may lead to a promising melanoma-cell specific therapy.

Method

We systematically analyzed the regulation of MITF with a novel established transcription factor based gene regulatory network model. Starting from comparative transcriptomics analysis using data from cells originating from nine different tumors and a melanoma cell dataset, we predicted the transcriptional regulators of MITF employing ChIP binding information from a comprehensive set of databases. The most striking regulators were experimentally validated by functional assays and an MITF-promoter reporter assay. Finally, we analyzed the impact of the expression of the identified regulators on clinically relevant parameters of melanoma, i.e. the thickness of primary tumors and patient overall survival.

Results

Our model predictions identified SOX10 and SOX5 as regulators of MITF. We experimentally confirmed the role of the already well-known regulator SOX10. Additionally, we found that SOX5 knockdown led to MITF up-regulation in melanoma cells, while double knockdown with SOX10 showed a rescue effect; both effects were validated by reporter assays. Regarding clinical samples, SOX5 expression was distinctively up-regulated in metastatic compared to primary melanoma. In contrast, survival analysis of melanoma patients with predominantly metastatic disease revealed that low SOX5 levels were associated with a poor prognosis.

Conclusion

MITF regulation by SOX5 has been shown only in murine cells, but not yet in human melanoma cells. SOX5 has a strong inhibitory effect on MITF expression and seems to have a decisive clinical impact on melanoma during tumor progression.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-016-0170-0) contains supplementary material, which is available to authorized users.

The impact of sequencing on diagnosis and treatment of malignant melanoma

Melanoma is one of the clinically most important cancer types considering its high mortality rate and that it is commonly diagnosed in relatively young people. With the advent of targeted therapies and, more recently, immune checkpoint inhibitors, more treatment options are available resulting in higher patient survival rates. However, the successful application of these targeted therapies critically depends on the reliable detection of molecular aberrations. Today, massively parallel sequencing techniques enable us to analyze large sets of genes in a relatively short time. It has allowed increased knowledge of acquired somatic mutations in melanoma and has helped to identify new targets for personalized therapy, and potentially may help to predict response to immune therapies. Described here are the development of sequencing techniques, how their improvement has changed diagnosis, prognosis and management of malignant melanoma and the future perspectives of melanoma diagnostics in the routine clinical setting.

Molecular techniques for predicting behaviour in melanocytic neoplasms

Molecular tools are rapidly emerging as novel tools for clinicians caring for cancer patients. Roles for these assays in melanocytic neoplasms include diagnosis for histologically ambiguous tumors, prognosis for conventional melanoma, and theragnosis for advanced disease. The introduction of these molecular strategies is timely, as different therapeutic options are rapidly developing to treat melanoma. With the development of new and effective therapeutic options, it is more critical than ever to improve the discrimination between patients with aggressive disease and those with more indolent tumours. In this review, we will evaluate the traditional staging of melanoma and what are the likely greatest opportunities for improvement with molecular strategies. We will explore a number of molecular assays that are now commercially available for the assessment of melanocytic neoplasms, which include techniques such as fluorescence in situ hybridisation, comparative genomic hybridisation, mRNA expression profiling and next generation sequencing, and discuss the optimal utilisation of each of these assays.

Competitive allele-specific TaqMan PCR (Cast-PCR) is a sensitive, specific and fast method for BRAF V600 mutation detection in Melanoma patients

BRAF codon 600 mutation testing of melanoma patients is mandatory for the choice of the most appropriate therapy in the clinical setting. Competitive allele specific TaqMan PCR (Cast-PCR) technology allows not only the selective amplification of minor alleles, but it also blocks the amplification of non-mutant allele. We genotyped codon 600 of the BRAF gene in 54 patients’ samples by Cast-PCR and bidirectional direct sequence analysis. All the mutations detected by sequencing were also identified by Cast-PCR. In addition, Cast-PCR assay detected four samples carrying mutations and was able to clearly identify two mutations of uncertain interpretation by Sanger sequencing. The limit of detection of Cast-PCR was evaluated by constructing dilution curves of BRAF^V600E and BRAF^V600K mutated clinical samples mixed with a not-mutated specimens. Both mutations could be detected until a 1:100 mutated/not mutated ratio. Cloning and sequencing of the clones was used to confirm mutations on representative discrepant cases. Cast PCR performances were not affected by intratumour heterogeneity, and less affected by melanin content. Our results indicate that Cast-PCR is a reliable diagnostic tool for the identification of melanoma patients as eligible to be treated with TKIs and might be implemented in the clinical setting as elective screening method.

BRAF and NRAS mutations are heterogeneous and not mutually exclusive in nodular melanoma

Inhibitors of RAF inhibit the MAPK pathway that plays an important role in the development and progression of those melanoma carrying the V600E BRAF mutation, but there’s a subset of such patients who do not respond to the therapy. Various mechanisms of drug resistance have been proposed which include the clonal heterogeneity of the tumor. We have studied a population of nodular melanoma to investigate the intratumor and intertumor heterogeneity by Laser Capture Microdissection (LCM) analysis. Our results showed that BRAF and NRAS mutations were detected in 47% and 33% of nodular melanoma, respectively, and that there is a discrepancy in mutational pattern of tumoral sample because in the 36% of patients a different mutation, in at least 1 area of the tumor, was found by LCM analysis, giving evidence of the presence of different clonal cells populations. Moreover, we found that mutations in BRAF and NRAS are not mutually exclusive because they were simultaneously present in the same tumor specimens and we observed that when the 2 different mutations were present one is a high-frequency mutation and the other is a low-frequency mutation. This was more evident in lymphonodal metastasis that resulted from wild type to mutational analysis, but showed different mutations following LCM analysis. Therefore, we believed that, when primary tumoral sample results negative to mutational analysis, if it is possible, metastases should be investigated to verify the presence of mutations. Generally, it should be searched for other mutations, in addition to BRAF V600E, so as to better understand the mechanism of drug resistance.

Identification of genes associated with melanoma metastasis

The aims of the study were to identify the differentially expressed genes (DEGs) between primary melanomas and metastasis melanomas (MMs), and to investigate the mechanisms of MMs. The microarray data GSE8401 including 31 primary melanomas and 52 MMs were downloaded from Gene Expression Omnibus. DEGs were identified using the Linear Models for Microarray Data package. The functional and pathway enrichment analyses were performed for DEGs. Identification of transcription factors, tumor-associated genes (TAGs), and tumor suppressor genes (TSGs) were performed with the TRANSFAC, TAG, and TSGene databases, respectively. A protein-protein interaction network was constructed using Search Tool for the Retrieval of Interacting Genes. The modules construction and analysis was performed using Molecular Complex Detection and Gene Cluster with Literature Profiles, respectively. In total, 1004 upregulated and 1008 downregulated DEGs were identified. The upregulated DEGs, such as CDK1, BRCA1, MAD2L1, and PCNA, were significantly enriched in cell cycles, DNA replication, and mismatch repair. The downregulated DEGs, such as COLIAL, COL4A5, COL18A1, and LAMC2, were enriched in cell adhesion and extracellular matrix-receptor interaction. BRCA1 was identified as a transcription factor and TSG, and COL18A1 and LAMC2 were identified as a TSG and TAG, respectively. The upregulated DEGs had higher degrees in the protein-protein interaction network and module, such as PCNA, CDK1, and MAD2L1, and the heat map showed they were clustered in the functions of cell cycle and division. These results may demonstrate the potential roles of DEGs such as CDK1, BRCA1, COL18A1, and LAMC2 in the mechanism of MM.

Dogs as a Model for Cancer

Spontaneous cancers in client-owned dogs closely recapitulate their human counterparts with respect to clinical presentation, histological features, molecular profiles, and response and resistance to therapy, as well as the evolution of drug-resistant metastases. In several instances the incorporation of dogs with cancer into the preclinical development path of cancer therapeutics has influenced outcome by helping to establish pharmacokinetic/pharmacodynamics relationships, dose/regimen, expected clinical toxicities, and ultimately the potential for biologic activity. As our understanding regarding the molecular drivers of canine cancers has improved, unique opportunities have emerged to leverage this spontaneous model to better guide cancer drug development so that therapies likely to fail are eliminated earlier and therapies with true potential are optimized prior to human studies. Both pets and people benefit from this approach, as it provides dogs with access to cutting-edge cancer treatments and helps to insure that people are given treatments more likely to succeed.

Precision cancer medicine: the future is now, only better

The promise of precision medicine for cancer is already being realized with the recent introduction of many targeted therapies, some with companion diagnostic tests that identify patients most likely to benefit from treatment. The utility of molecular profiling of cancer to identify actionable aberrations has been suggested by several small clinical trials conducted in patients with advanced cancer and by many anecdotes but is yet to be proven in well-designed, prospective, randomized trials. Several trials that will definitively test this strategy are now underway or soon to be launched. Melanoma, a disease once largely untreatable when metastatic, may be a paradigm for understanding how the molecular drivers of a disease can lead to highly effective targeted therapies, as well as for realizing the enormous therapeutic potential of unleashing the immune system against cancer to produce long-term disease control. Looking to the future, advanced omics technologies and computational techniques will enable assessment of not only genomic variants, as performed today, but also of pathway and network aberrations that will greatly facilitate selection of drug combinations likely to benefit specific patients. As our deepening understanding of tumor biology converges with rapid advances in measurement science and technology and computational analysis, we have an enormous opportunity to create a future for precision medicine in oncology that provides for highly specific, minimally toxic, and dramatically effective treatment for each patient.

Current State of Animal (Mouse) Modeling in Melanoma Research

Despite the considerable progress in understanding the biology of human cancer and technological advancement in drug discovery, treatment failure remains an inevitable outcome for most cancer patients with advanced diseases, including melanoma. Despite FDA-approved BRAF-targeted therapies for advanced stage melanoma showed a great deal of promise, development of rapid resistance limits the success. Hence, the overall success rate of melanoma therapy still remains to be one of the worst compared to other malignancies. Advancement of next-generation sequencing technology allowed better identification of alterations that trigger melanoma development. As development of successful therapies strongly depends on clinically relevant preclinical models, together with the new findings, more advanced melanoma models have been generated. In this article, besides traditional mouse models of melanoma, we will discuss recent ones, such as patient-derived tumor xenografts, topically inducible BRAF mouse model and RCAS/TVA-based model, and their advantages as well as limitations. Although mouse models of melanoma are often criticized as poor predictors of whether an experimental drug would be an effective treatment, development of new and more relevant models could circumvent this problem in the near future.

Novel Therapies for Metastatic Melanoma: An Update on Their Use in Older Patients

Cutaneous melanoma is the most aggressive form of skin cancer. With age as a risk factor, melanoma is projected to become a substantial healthcare burden. The clinical course of melanoma in older patients is different from that in middle-aged and younger patients: melanomas are thicker, have higher mitotic rates and are more likely to be ulcerated. Older patients also have a higher mortality rate, yet, paradoxically, have a lower rate of lymph node metastases. After decades of no significant progress in the treatment of this devastating disease, novel insights into the mechanisms underlying the pathophysiology of metastatic melanoma have led to new and remarkably efficient therapeutic opportunities. The discovery that about half of all melanomas carry BRAF mutations led to the introduction of targeted therapy with significant improvements in clinical outcomes. Although these drugs appear to be equally effective in older patients, specific considerations regarding adverse events are required. Besides targeted therapy, immunotherapy has emerged as an alternative therapeutic option. Antibodies that block cytotoxic T-lymphocyte antigen 4 (CTLA-4) and programmed cell death protein 1 (PD-1) can induce responses with high durability. Despite an aging immune system, older patients seem to benefit to the same degree from these treatments, apparently without increased toxicity. In this review, we focus on the epidemiology, clinicopathological features, and recent developments of systemic treatment in cutaneous melanoma with regard to older patients.

Photodynamic therapy of melanoma skin cancer using carbon dot - chlorin e6 - hyaluronate conjugate

Despite wide application of photodynamic therapy (PDT) for the treatment of melanoma skin cancers, there are strong biomedical unmet needs for the effective generation of singlet oxygen after targeted delivery of photosensitizers. Here, we investigated a facile PDT of melanoma skin cancer using transdermal carbon dot - chlorine e6 - hyaluronate (Cdot-Ce6-HA) conjugates. The Cdot-Ce6-HA conjugate was synthesized by the coupling reaction of diaminohexane modified HA (DAH-HA) with the carboxylic group of Ce6. The singlet oxygen generation of Cdot-Ce6-HA conjugates in aqueous solution was more significant than that of free Ce6. The enhanced transdermal and intracellular delivery of Cdot-Ce6-HA conjugates to B16F10 melanoma cells in tumor model mice were corroborated by confocal microscopy and two-photon microscopy. The laser irradiation after topical treatment with Cdot-Ce6-HA conjugates resulted in complete suppression of melanoma skin cancers. The antitumor effect was confirmed by histological analysis with H&E staining and TUNEL assay for tumor apoptosis. Taken together, we could confirm the feasibility of Cdot-Ce6-HA conjugate for transdermal PDT of melanoma skin cancers.

STATEMENT OF SIGNIFICANCE

To our knowledge, this is the first report on a facile transdermal photodynamic therapy (PDT) of melanoma skin cancer using carbon dot - chlorine e6 - hyaluronate (Cdot-Ce6-HA) conjugates. We found that the singlet oxygen generation of Cdot-Ce6-HA conjugates in aqueous solution was more significant than that of free Ce6. Confocal microscopy and two-photon microscopy clearly confirmed the enhanced transdermal and intracellular delivery of Cdot-Ce6-HA conjugates to B16F10 melanoma cells in tumor model mice. Taken together, we could confirm the feasibility of Cdot-Ce6-HA conjugate for transdermal PDT of melanoma skin cancers.

Telomere length and the risk of cutaneous melanoma and non-melanoma skin cancer: a review of the literature and meta-analysis

There is much evidence supporting the role of telomeres in cancer pathogenesis, however the studies that investigated the association between telomere length and skin cancer risk provided inconsistent results. To help clarify this issue, we performed a systematic review and meta-analysis of published papers on the association between peripheral leukocytes telomere length (PLTL) and the risk of cutaneous melanoma and non-melanoma skin cancer (NMSC). We calculated summary relative risks (SRR) and 95% confidence intervals (95% CI) using random effect models with maximum likelihood estimates, and explored causes of between-studies heterogeneity of risk estimates. We included 1629 cutaneous melanoma and 1439 NMSC from eight independent studies published until March 2015. The SRR of cutaneous melanoma for those in the lowest (vs. highest) category of PLTL distribution was 0.25 (95% CI 0.09-0.67). The results were less clear for NMSC, with two studies reporting no association and one study showing an increase in risk for those in the lowest (vs. highest) category of PLTL distribution. For both cutaneous melanoma and NMSC, the between-studies heterogeneity was large, mainly due to inclusion of hospital-based case-control studies. Our meta-analysis shows evidence of an association between short PLTL and reduced risk for cutaneous melanoma.

Multiple Molecular Pathways in Melanomagenesis: Characterization of Therapeutic Targets

Molecular mechanisms involved in pathogenesis of malignant melanoma have been widely studied and novel therapeutic treatments developed in recent past years. Molecular targets for therapy have mostly been recognized in the RAS–RAF–MEK–ERK and PI3K–AKT signaling pathways; small-molecule inhibitors were drawn to specifically target key kinases. Unfortunately, these targeted drugs may display intrinsic or acquired resistance and various evidences suggest that inhibition of a single effector of the signal transduction cascades involved in melanoma pathogenesis may be ineffective in blocking the tumor growth. In this sense, a wider comprehension of the multiple molecular alterations accounting for either response or resistance to treatments with targeted inhibitors may be helpful in assessing, which is the most effective combination of such therapies. In the present review, we summarize the known molecular mechanisms underlying either intrinsic and acquired drug resistance either alternative roads to melanoma pathogenesis, which may become targets for innovative anticancer approaches.

NRAS (Q61R), BRAF (V600E) immunohistochemistry: a concomitant tool for mutation screening in melanomas

Background

The determination of NRAS and BRAF mutation status is a major requirement in the treatment of patients with metastatic melanoma. Mutation specific antibodies against NRAS^Q61R and BRAF^V600E proteins could offer additional data on tumor heterogeneity. The specificity and sensitivity of NRAS^Q61R immunohistochemistry have recently been reported excellent. We aimed to determine the utility of immunohistochemistry using SP174 anti-NRAS^Q61R and VE1 anti-BRAF^V600E antibodies in the theranostic mutation screening of melanomas.

Methods

142 formalin-fixed paraffin-embedded melanoma samples from 79 patients were analyzed using pyrosequencing and immunohistochemistry.

Results

23 and 26 patients were concluded to have a NRAS-mutated or a BRAF-mutated melanoma respectively. The 23 NRAS^Q61R and 23 BRAF^V600E-mutant samples with pyrosequencing were all positive in immunohistochemistry with SP174 antibody and VE1 antibody respectively, without any false negative. Proportions and intensities of staining were varied. Other NRAS^Q61L, NRAS^Q61K, BRAF^V600K and BRAF^V600R mutants were negative in immunohistochemistry. 6 single cases were immunostained but identified as wild-type using pyrosequencing (1 with SP174 and 5 with VE1). 4/38 patients with multiple samples presented molecular discordant data. Technical limitations are discussed to explain those discrepancies. Anyway we could not rule out real tumor heterogeneity.

Conclusions

In our study, we showed that combining immunohistochemistry analysis targeting NRAS^Q61R and BRAF^V600E proteins with molecular analysis was a reliable theranostic tool to face challenging samples of melanoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s13000-015-0359-0) contains supplementary material, which is available to authorized users.