BRAF and NRAS mutations are uncommon in melanomas arising in diverse internal organs

BACKGROUND: Malignant melanoma arising from different body compartments may be associated with differing aetiological factors and clinical behaviour, and may manifest diverse molecular genetic profiles. Although many studies have focused on cutaneous melanoma, little is known of mucosal and other types of melanoma. In particular, malignant melanoma of soft parts is different from other melanomas in many respects, yet manifests a common melanocytic differentiation. Mutation of BRAF is now known to be common in cutaneous melanomas, and raises possible new therapeutic options of anti-RAF treatment for these patients. Few data are available for non-cutaneous melanomas. AIMS: To study the incidence of BRAF and NRAS mutations in melanomas arising in diverse internal organs. METHODS: Fifty one melanomas from various internal organs were investigated for BRAF and NRAS mutation by direct DNA sequencing. RESULTS: BRAF and NRAS mutations were found in two and five mucosal melanomas arising from the aerodigestive and female genital tracts (n = 36). Their occurrence is mutually exclusive, giving a combined mutation incidence rate of 19.4% in mucosal melanomas. Both BRAF and NRAS mutations were absent in malignant melanoma of soft parts (n = 7). BRAF mutation was also absent in uveal melanoma (n = 6), but was seen in two of five cutaneous melanomas. The incidence of BRAF or combined BRAF/NRAS mutations in all non-cutaneous groups was significantly lower than published rates for cutaneous melanomas. CONCLUSION: Each melanoma subtype may have a unique oncogenetic pathway of tumour development, and only a small fraction of non-cutaneous melanomas may benefit from anti-RAF treatment.     

RSK1 Activation Promotes Invasion in Nodular Melanoma

The two major melanoma histologic subtypes, superficial spreading and nodular melanomas, differ in their speed of dermal invasion but converge biologically once they invade and metastasize. Herein, we tested the hypothesis that distinct molecular alterations arising in primary melanoma cells might persist as these tumors progress to invasion and metastasis. Ribosomal protein S6 kinase, 90 kDa, polypeptide 1 (RSK1; official name RPS6KA1) was significantly hyperactivated in human melanoma lines and metastatic tissues derived from nodular compared with superficial spreading melanoma. RSK1 was constitutively phosphorylated at Ser-380 in nodular but not superficial spreading melanoma and did not directly correlate with BRAF or MEK activation. Nodular melanoma cells were more sensitive to RSK1 inhibition using siRNA and the pharmacological inhibitor BI-D1870 compared with superficial spreading cells. Gene expression microarray analyses revealed that RSK1 orchestrated a program of gene expression that promoted cell motility and invasion. Differential overexpression of the prometastatic matrix metalloproteinase 8 and tissue inhibitor of metalloproteinases 1 in metastatic nodular compared with metastatic superficial spreading melanoma was observed. Finally, using an in vivo zebrafish model, constitutive RSK1 activation increased melanoma invasion. Together, these data reveal a novel role for activated RSK1 in the progression of nodular melanoma and suggest that melanoma originating from different histologic subtypes may be biologically distinct and that these differences are maintained as the tumors invade and metastasize.Superficial spreading melanoma (SSM) and nodular melanoma (NM) represent the two most common primary melanoma histologic subtypes, accounting for 70% and 15% to 20% of cases, respectively.^1,2 SSM is characterized by a radial growth phase (RGP) consisting of an intraepidermal component. Whereas SSM can proceed from a RGP to a vertical growth phase (VGP) and finally to distant metastases, NM grows rapidly in a vertical manner (VGP), with no horizontal growth phase.³To date, the prognostic and therapeutic impact of melanoma histologic subtypes has been relatively limited. The American Joint Committee on Cancer staging system uses tumor thickness, ulceration, mitotic index, and lymph node status, but not histologic subtype, in the recurrence/metastasis risk assessment of patients with primary localized melanoma.⁴ This is, in part, due to the current linear model of melanoma progression, which dictates that melanoma begins with the transformation of epidermal melanocytes and an initial RGP, followed by a subsequent transition to a VGP and distant metastasis.^5–7 Hence, it is generally accepted that the speed of dermal invasion is the only aspect that differentiates the NM and SSM subtypes.Recent discoveries in other solid tumor types emphasize the potential role of histology-driven molecular characterization to assist in the diagnosis and treatment of cancer.^8–11 Indeed, the utility of histologic classification in melanoma has been demonstrated with acral lentiginous melanoma, which composes approximately 10% of primary melanomas. The prevalence of molecular alterations in the c-KIT oncogene in this histologic melanoma subtype has defined acral lentiginous melanoma as a distinct and useful subclassification of melanoma, and a phase 2 trial of the c-KIT inhibitor imatinib validated the rationale of subtype-specific therapy for this group of melanoma patients.¹² In contrast, the clinical relevance of the SSM and NM subtypes has been largely overlooked.Recent reports by our groups and others suggest that primary SSM and NM might be distinct biological entities.^13–19 Unbiased, high-throughput genetic techniques, such as comparative genomic hybridization, single nucleotide polymorphism arrays, and microarrays, have revealed the presence of recurrent SSM-specific deletions that are present or even amplified in NM and, thus, cannot be reconciled with the linear progression model, even when epigenetic modifications are taken into account. Similarly, significant alterations in mRNA and miRNA gene expression are observed when comparing SSM with nevi and NM, and these alterations cannot be explained by the existing stepwise (linear) model.^16,17 Together, these findings suggest that distinct molecular alterations between SSM and NM might underlie the biological differences between these subtypes. However, it is unclear whether differences that exist between primary SSM and NM are retained during progression to invasion and metastasis.Herein, we tested the hypothesis that subtype-specific differences between SSM and NM persist throughout progression of primary melanoma to metastatic disease. We used a combination of human melanoma cell lines representing SSM and NM, human tissues from metastatic SSM and NM, and a zebrafish model of melanoma to demonstrate the role of protein S6 kinase, 90 kDa, polypeptide 1 (RSK1; official name RPS6KA1) in melanoma invasion in vitro and in vivo. These data suggest that metastatic melanoma originating from different histologic subtypes might be biologically distinct and reveal differences that are maintained from the primary tumor to metastatic disease.     

Synchronous Occurrence of Medullary and Papillary Carcinoma of the Thyroid in a Patient with Cutaneous Melanoma: Determination of BRAFV600E in Peripheral Blood and Tissues. Report of a Case and Review of the Literature

The purpose of this study is to describe a case of concurrent medullary and papillary thyroid carcinoma (MTC and PTC) and cutaneous melanoma and to analyze BRAF^V600E mutation in plasma and tissues. We report the clinical history and the laboratory, imaging, and histopathological findings of a 47-year-old man affected by multinodular goiter. BRAF^V600E-mutated DNA was quantified in plasma samples and in cancer sections by quantitative real-time polymerase chain reaction (qPCR). At ultrasound examination, the dominant right nodule of the thyroid was weakly hyperechoic and hypervascularized, while the left one was hypoechoic without internal vascularization. Regional lymphadenomegalia was not detected. Basal plasma calcitonin was elevated, and the patient underwent total thyroidectomy and resection of central cervical lymph nodes. Histopathological examination identified two distinct foci of MTC and PTC and micrometastasis of well-differentiated carcinoma in one of the six resected lymph nodes. RET proto-oncogene germline mutations were not detected. Cutaneous melanoma of the thorax was subsequently diagnosed. BRAF^V600E tissue DNA was detected in PTC and melanoma but not in MTC. The cell-free plasma percentage of BRAF^V600E DNA was detected in pre-thyroidectomy peripheral blood and was drastically reduced after cancer treatments. This study confirms the occurrence of synchronous MTC and PTC and is the first evidence of the co-existence of melanoma and distinct thyroid cancers of different origin. BRAF^V600E allele was detected in PTC and melanoma but not in MTC tissues. BRAF^V600E molecular quantification in pre- and post-treatment blood supports our previous data, suggesting its possible role in diagnosis and follow-up of BRAF-positive tumors.     

Distinct patterns of DNA copy number alterations associate with BRAF mutations in melanomas and melanoma‐derived cell lines

A majority of malignant melanomas harbor an oncogenic mutation in either BRAF or NRAS. If BRAF and NRAS transform melanoma cells by a similar mechanism, then additional genetic aberrations would be similar (or random). Alternatively, distinct mutation‐associated changes would suggest the existence of unique cooperating requirements for each mutation group. We first analyzed a panel of 52 melanoma cell lines (n = 35, 11, 6 for BRAF*, NRAS*, and BRAF/NRAS^wt/wt, respectively) by array‐based comparative genomic hybridization for unique alterations that associate with each mutation subgroup. Subsequently, those DNA copy number changes that correlated with a mutation subgroup were used to predict the mutation status of an independent panel of 43 tumors (n = 17, 13, 13 for BRAF*, NRAS*, and BRAF/NRAS^wt/wt, respectively). BRAF mutant tumors were classified with a high rate of success (74.4%, P = 0.002), whereas NRAS mutants were not significantly distinguished from wild types (26/43, P = 0.12). Copy number gains of 7q32.1‐36.3, 5p15.31, 8q21.11, and 8q24.11 were most strongly associated with BRAF* tumors and cell lines, as were losses of 11q24.2‐24.3. BRAF* melanomas appear to be associated with a specific profile of DNA copy number aberrations that is distinct from those found in NRAS* and BRAF/NRAS^wt/wt tumors. These findings suggest that although both BRAF and NRAS appear to function along the same signal transduction pathway, each may have different requirements for cooperating oncogenic events. The genetic loci that make up this profile may harbor therapeutic targets specific for tumors with BRAF mutations. © 2009 Wiley‐Liss, Inc.     

Pleural metastasis from auricular melanoma: A brief report

Primary auricular melanoma is rarely reported. Approximately, it accounts for 1% to 4% of all cutaneous melanoma. Early literature suggested that melanoma of the ear is more aggressive than other melanomas, with a propensity for spreading to both regional lymph nodes and distant sites. Here, we present a case of cytological pleural metastasis from auricular melanoma in a 43‐year‐old woman. Immunohistochemical staining showed that the tumors cells were positive for S‐100 protein and Melan‐A. The mutation of the v‐raf murine sarcoma viral oncogene homolog B (BRAF)^V600E was demonstrated on Sanger sequencing. To our knowledge, this is the first report describing the cytomorphology of metastatic auricular melanoma in pleural effusion.     

Molecular testing in malignant melanoma

Molecular testing of cancers to determine therapeutic eligibility is now standard of care and has changed the practice of pathology. Recent advances in the treatment of metastatic melanoma with BRAF and KIT inhibitors have increased the demand for molecular testing in melanoma. Furthermore, rapid progress is being made in determining potential new targets, mechanisms of resistance, and developing additional rationally designed therapies. The likely consequence will be a significant expansion of molecular testing for melanoma to include an array of multiple signaling intermediates. Currently, routine testing is mostly limited to BRAF and KIT. Mutations in these genes generally occur in a distinct group of melanoma subsets though, and with the numerous techniques available for mutation analysis, decisions about testing can be complex. The purpose of this review is to provide an overview of clinically relevant mutations which currently guide systemic therapy in Stage IV melanoma, how these molecular events vary with melanoma subtype and primary site of origin, and practical recommendations for testing.     

BRAF在10-姜酚抗黑色素瘤中作用的分子模拟及实验研究

目的:采用分子模拟技术及细胞实验研究BRAF蛋白在10-姜酚(10-G)抗黑色素瘤中的作用。方法:将10-G(10、20和40μmol/L)刺激人皮肤黑色素瘤A375细胞24 h,采用MTS法和细胞计数检测细胞活力。采用分子对接及分子动力学模拟分析10-G与BRAF蛋白之间的相互关系。采用Western blot技术检测p-BRAF、总BRAF、p-MEK1/2、p-ERK1/2和p-P38的蛋白水平。结果:10-G可剂量依赖性地降低A375细胞活力和数量,与对照组比较差异有统计学意义(P 0. 01)。10-G与野生型BRAF之间的结合能为-7. 358 kcal/mol,与V600E突变型的BRAF之间的结合能为-8. 255 kcal/mol。分子动力学模拟证实BRAF~(V600E)与10-G之间的结合是稳定的。10-G能显著抑制A375细胞中p-BRAF、p-MEK1/2和p-P38的蛋白水平(P 0. 01),对p-ERK1/2的蛋白水平没有影响。结论:10-G能够抑制黑色素瘤细胞的生长,其机制可能与抑制BRAF激活有关。     

The CSPG4-specific monoclonal antibody enhances and prolongs the effects of the BRAF inhibitor in melanoma cells

PLX4032 is a BRAF-selective inhibitor shown to be efficacious in the treatment of melanomas presenting with the BRAF(V600E) mutation. However, favorable responses to treatment are short-lived, and complete remission is rarely observed. Therefore, it is important to identify novel therapies designed to enhance treatment responses and to increase the longevity of initial response to BRAF inhibitors. To this end, we characterized the effects of the 225.28 chondroitin sulfate proteoglycan 4 (CSPG4)-specific monoclonal antibody (mAb) capable of blocking multiple signaling pathways important to cell growth, migration, and survival. Addition of 225.28 to the treatment regimen enhanced the in vitro response magnitude and the duration efficacy of PLX4032 in treating CSPG4(+), BRAF(V600E) melanoma cells (melanoma(BRAF(V600E)/CSPG4+) cells). Data presented in this report demonstrated that (1) treatments comprised of PLX4032 and mAb 225.28 were more effective at inhibiting melanoma(BRAF(V600E)/CSPG4+) cell growth than either agent alone, (2) mAb 225.28 prevented/delayed the development of resistance in melanoma(BRAF(V600E)/CSPG4+) cells to PLX4032, and (3) the mechanism of action of the combination therapy caused a down-regulation in multiple signaling pathways. This study provides a foundation for future investigations designed to improve BRAF inhibitor effectiveness in vitro and in vivo for treating melanoma(BRAF(V600E)/CSPG4+) cells in combination with a CSPG4-specific mAb.     

Toward rapid learning in cancer treatment selection: An analytical engine for practice-based clinical data

ObjectiveWide-scale adoption of electronic medical records (EMRs) has created an unprecedented opportunity for the implementation of Rapid Learning Systems (RLSs) that leverage primary clinical data for real-time decision support. In cancer, where large variations among patient features leave gaps in traditional forms of medical evidence, the potential impact of a RLS is particularly promising. We developed the Melanoma Rapid Learning Utility (MRLU), a component of the RLS, providing an analytical engine and user interface that enables physicians to gain clinical insights by rapidly identifying and analyzing cohorts of patients similar to their own.Materials and methodsA new approach for clinical decision support in Melanoma was developed and implemented, in which patient-centered cohorts are generated from practice-based evidence and used to power on-the-fly stratified survival analyses. A database to underlie the system was generated from clinical, pharmaceutical, and molecular data from 237 patients with metastatic melanoma from two academic medical centers. The system was assessed in two ways: (1) ability to rediscover known knowledge and (2) potential clinical utility and usability through a user study of 13 practicing oncologists.ResultsThe MRLU enables physician-driven cohort selection and stratified survival analysis. The system successfully identified several known clinical trends in melanoma, including frequency of BRAF mutations, survival rate of patients with BRAF mutant tumors in response to BRAF inhibitor therapy, and sex-based trends in prevalence and survival. Surveyed physician users expressed great interest in using such on-the-fly evidence systems in practice (mean response from relevant survey questions 4.54/5.0), and generally found the MRLU in particular to be both useful (mean score 4.2/5.0) and useable (4.42/5.0).DiscussionThe MRLU is an RLS analytical engine and user interface for Melanoma treatment planning that presents design principles useful in building RLSs. Further research is necessary to evaluate when and how to best use this functionality within the EMR clinical workflow for guiding clinical decision making.ConclusionThe MRLU is an important component in building a RLS for data driven precision medicine in Melanoma treatment that could be generalized to other clinical disorders.     

Comparing BRAF mutation status in matched primary and metastatic cutaneous melanomas: Implications on optimized targeted therapy

Background

Selective BRAF inhibitors have shown dramatic results with regard to improving outcome in patients with melanoma. Testing the BRAF status in matched primary and metastatic melanomas to optimize individual targeted therapy is not well investigated.

Methods

Extended BRAF testing using PCR for 9 mutations and VE1 immunohistochemistry for BRAF V600E detection on 95 lesions including 40 primary melanomas with their matched metastases (n = 42), recurrences (n = 9) and second primaries (n = 4) was performed. Nine patients had multiple metastases.

Results

V600E was the only identified mutation type; 35.4% of primary vs. 18.9% of metastatic melanomas. The overall primary-metastatic BRAF status discordance rate was 32.3% using PCR and 27.5% with immunohistochemistry, and was significantly more frequent in primary lesions with mutant BRAF (67%). Males and patients with metastasis to lymph nodes were less likely to be discordant compared to females and those with metastasis to other sites (p = 0.023). Discordant BRAF mutation status was predicted by multivariate binary logistic regression: the presence of a mutant BRAF in the primary melanoma [OR (95% C.I.) = 23.4 (2.4–229.7)] and female gender [OR = 10.6 (1.08–95)]. Inter-metastases BRAF concordance was 100% (6 comparisons).

Conclusion

A high discordant rate implies the need for clinical trials addressing the response to targeted therapy in patients with discordant BRAF statuses between their primary and metastatic lesions.     

Sunlight ultraviolet irradiation and BRAF V600 mutagenesis in human melanoma

The incidence of melanoma, the most lethal form of skin cancer, continues to increase in the Western world. In addition to genetic alterations in high- and low-susceptibility genes identified for melanoma, somatic mutations in BRAF gene occur frequently in human melanoma and are distinctively linked to sun exposure. Of significance is a single hotspot codon, i.e., BRAF V600, wherein up to 92% of all mutations arise. Recent work in our laboratory has demonstrated that solar ultraviolet (UV) irradiation triggers mutagenesis through induction of various DNA lesions, many of which capable of producing similar types of mutations, as those seen in BRAF V600 variants in human melanoma. In this review article, we have discussed application of "DNA damage-targeted mutagenicity" of solar UV-irradiation for determining the mechanistic involvement of sunlight UV in BRAF V600 mutagenesis in human melanoma. We envision that establishing "DNA-damage derived mutagenesis" in this exceptionally unique target gene may resolve the underlying mechanism(s) of melanoma-genesis, thus helping define preventive and therapeutic measures against this malignant disease.     

Sarcoidosis related to checkpoint and BRAF/MEK inhibitors in melanoma

Therapy for advanced melanoma has deeply changed in the last decade with the introduction of checkpoint and BRAF/MEK inhibitors. Granulomatous reactions have been reported related to these drugs. We performed a systematic review of all the cases described in the medical literature by the search ((“Melanoma”[Mesh]) AND (“Sarcoidosis”[Mesh] OR “Granuloma”[Mesh])). Ninety-one patients under immunotherapy were included in the analyses. The time from the initiation of the immunotherapy until the onset of sarcoidosis or sarcoid-like reaction (SLR) was 7.1 months (SD 9). Peripheral lymph nodes as the mode of onset were seen more frequently in patients under CTLA-4 inhibitors (p = .016) whereas in patients under BRAF/MEK inhibitors used to be in the form of specific skin lesions (p = .006). Chest X-ray stage I-II was the rule in the CTLA-4 and PD-1 groups. On the contrary, stage 0 accounted for 80% of the patients in the BRAF/MEK group examined for pulmonary involvement. Specific skin involvement was the most common manifestation apart from pulmonary involvement. It was more frequent in patients under BRAF/MEK inhibitors and especially in the form of papules. Splenic involvement was found also more frequently in patients under CTLA-4 inhibitors. Specific treatment for sarcoidosis/SLR was prescribed in 50 patients (58.8%), without differences among groups. Almost all patients presented a good prognosis independently of the decision made regarding their previous immunotherapy.ConclusionPhysicians should bear in mind the possibility of sarcoidosis/SLR after the initiation of checkpoint or BRAF/MEK inhibitors in patients diagnosed with advanced melanoma, especially in the form of skin involvement and mediastinal and peripheral lymph nodes. It is important to achieve an accurate diagnosis to rule out the possibility of cancer involvement. What to do with these drugs is yet to be clarified. It seems reasonable to prioritize cancer treatment so it is not mandatory to stop these drugs.     

Novel V600E BRAF mutations in imatinib-naive and imatinib-resistant gastrointestinal stromal tumors

BRAF and NRAS are commonly mutated in cancer and represent the most frequent genetic events in malignant melanoma. More recently, a subset of melanomas was shown to overexpress KIT and harbor KIT mutations. Although most gastrointestinal stromal tumors (GISTs) exhibit activating mutations in either KIT or PDGFRA, about 10% of the cases lack mutations in these genes. It is our hypothesis following the melanoma model that mutations in BRAF or NRAS may play a role in wild-type GIST pathogenesis. Alterations in RAS/MEK/ERK pathway may also be involved in development of imatinib resistance in GIST, particularly in tumors lacking secondary KIT or PDGFRA mutations. Imatinib-naive wild-type GISTs from 61 patients, including 15 children and 28 imatinib-resistant tumors without secondary KIT mutations were analyzed. Screening for hot spots mutations in BRAF (exons 11 and 15) and NRAS (exons 2 and 3) was performed. A BRAF exon 15 V600E was identified in 3 of 61 GIST patients, who shared similar clinical features, being 49- to 55-years-old females and having their tumors located in the small bowel. The tumors were strongly KIT immunoreactive and had a high risk of malignancy. An identical V600E BRAF mutation was also identified in one of 28 imatinib resistant GIST lacking a defined mechanism of drug resistance. In conclusion, we identified a primary BRAF V600E mutations in 7% of adult GIST patients, lacking KIT/PDGFRA mutations. The BRAF-mutated GISTs show predilection for small bowel location and high risk of malignancy. A secondary V600E BRAF mutation could represent an alternative mechanism of imatinib resistance. Kinase inhibitors targeting BRAF may be effective therapeutic options in this molecular GIST subset.     

Dividing and conquering: controlling advanced melanoma by targeting oncogene-defined subsets

For decades, therapy for advanced melanoma has lagged behind most of the cancer field owing to its intrinsic resistance to conventional cytotoxic chemotherapy and limited impact of cytokine-based immunotherapy. The opportunity to develop molecularly targeted therapy emerged with the discovery of activating mutations in BRAF, a component of the long studied MAP kinase pathway. These mutations are found in approximately 50 % of patients with regionally advanced or metastatic melanoma and appear to be one of the initiating steps in the development of primary melanoma. Additional oncogenic events, particularly those that affect tumor suppressor genes, are essential for development of invasive and metastatic melanoma. Nonetheless, mutated BRAF retains its central contribution to melanoma pathophysiology even in advanced stage disease as manifested by the remarkable antitumor effects and alteration the natural history of metastatic melanoma of selective BRAF inhibitors. After initial response, resistance commonly emerges within a few months’ time and the field has focused on delineating molecular mechanisms of resistance toward the goal of improving upon the early therapeutic effects of single agent BRAF inhibition. Combination regimens are currently undergoing clinical investigation. NRAS and CKIT mutant melanoma represent the next oncogene defined melanoma subsets for which initial targeted therapy approaches are being explored, with early evidence suggesting progress with MEK and CKIT inhibitors, respectively. A considerable subset of patients have melanomas that are not defined by the presence of BRAF, NRAS, or CKIT mutations and, thus, the elucidation of the entire melanoma genome is being pursued with the hope of identifying additional therapeutic targets.     

43例中国眼部恶性黑色素瘤cKit和BRAF基因突变分析

 目的 分析中国眼部恶性黑色素瘤中cKit和BRAF基因突变情况。方法 收集43例中国眼部恶性黑色素瘤患者组织标本（脉络膜恶性黑色素瘤30例,结膜恶性黑色素瘤13例）, 采用巢式PCR扩增和基因测序的方法检测cKit基因第9,11,13,17,18外显子以及BRAF基因第15外显子突变情况。结果cKit基因在脉络膜恶性黑色素瘤患者中突变率达16.7%(5/30),而在结膜恶性黑色素瘤中突变率仅为7.7% (1/13);在结膜恶性黑色素瘤中检测到1例BRAF基因突变(1/13),在脉络膜恶性黑色素瘤中未检测到BRAF基因突变。结论 本研究首次报道cKit基因在中国脉络膜恶性黑色素瘤患者中突变率较高,提示以cKit为靶标的靶向药物未来有可能为中国眼部恶性黑色素瘤患者,尤其是脉络膜恶性黑色素瘤患者带来新的希望。     

KRAS and BRAF mutations in anal carcinoma

The EGF receptor (EGFR) is expressed in most cases of anal carcinomas. Anecdotal benefit from EGFR‐targeted therapy has been reported in anal cancer and a negative correlation with Kirsten Ras (KRAS) mutation status has been proposed. The purpose of this retrospective study was to investigate the frequency and the prognostic value of KRAS and BRAF mutations in a large cohort of patients with anal cancer. One hundred and ninety‐three patients with T1‐4N0‐3M0‐1 anal carcinoma were included in the study . Patients were treated with curative (92%) or palliative intent (8%) between January 2000 and January 2010. KRAS mutations were detected using Therascreen^®KRAS real‐time PCR assay (Qiagen) and V600E or V600D/K BRAF mutations were uncovered using Pyrosequencing. The frequency of KRAS and BRAF mutations was low; KRAS mutations were detected in 1.6% and BRAF mutations in 4.7% of the biopsies. No impact of KRAS or BRAF status on survival was found. In conclusion, both KRAS and BRAF mutations are rare in anal cancer. The low frequency of KRAS mutations support protocols exploring EGFR‐targeted therapy in patients with metastatic anal cancer, while treatment with BRAF inhibitors might be relevant for only a very few patients.     

Absence of mutations of the BRAF gene and constitutive activation of extracellular-regulated kinase in malignant melanomas of the uvea

The v-raf murine sarcoma viral homolog B1 (BRAF) gene, one of the human isoforms of RAF, is activated by Ras, leading to cooperative effects in cells responsive to growth factor signals. Recently, somatic missense mutations of the BRAF gene have been detected in more than 66% of malignant melanomas of the skin. We analyzed 42 malignant melanomas of the uvea, 3 corresponding liver metastases, and 10 cutaneous melanomas for possible BRAF mutations: after microdissection, mutation analysis of BRAF and KRAS was performed. The expression of extracellular-regulated kinase 1 and 2 (ERK1/2), an important downstream point of convergence in the Ras-RAF-MEK-Erk pathway, was analyzed immunohistochemically. Interestingly, we failed to detect activating BRAF mutations in uvea melanomas and their corresponding liver metastases. There were no mutations of BRAF in corresponding non-neoplastic uvea specimens, although we detected three BRAF mutations in sporadic cutaneous melanoma that led to a substitution of valine by glutamic acid at position 599 (V599E). KRAS mutations were detected in 1 of 10 cutaneous melanoma but not in uveal or metastatic melanoma. Despite the lack of activating mutations in the BRAF gene, we identified constitutively activated ERK in almost all (86%) uveal melanoma tissues tested but not in corresponding normal retina or uveal cells. Our data indicate that BRAF gene mutations are rare to absent events in uveal melanoma. The finding of activated Erk suggests a causative role for MAPK activation in uveal melanoma independent of activating BRAF or RAS mutations.