High Prevalence Of BRAF V600E Mutation Research Articles

Progression of Papillary Thyroid Carcinoma to Anaplastic Carcinoma in Metastatic Lymph Nodes: Solid/Insular Growth and Hobnail Cell Change in Lymph Nodes Are Predictors of Subsequent Anaplastic Transformation

Most anaplastic thyroid carcinomas (ATCs) arise from papillary thyroid carcinoma (PTC). This process is also called anaplastic transformation, and the morphological harbingers of this phenomenon in nodal recurrence have not been assessed systematically. For this reason, the current study focused on features of 10 PTCs with regional lymph node recurrence that was accompanied with disease progression due to anaplastic transformation in at least one of the nodal recurrences. The findings of additional 19 PTCs which recurred without anaplastic transformation after ≥ 10 years of follow-up served as the control group. There were no clinicopathological differences between the two groups at initial surgery including age, gender, tumor size, lymph node metastasis, distant metastasis, extrathyroidal extension, histologic subtype, and treatment. The median time from the initial thyroid surgery to anaplastic transformation in the nodal recurrence was 106 months (range 6 to 437 months). Mutational analyses showed recurrent PTCs with anaplastic transformation had a high prevalence of BRAFV600E mutation (8/9) and TERT promoter mutation (9/9), both of which were detected in primary tumors. PIK3CAH1047R mutation was detected in one case. No case had RAS mutation. Nineteen recurrent PTCs without anaplastic transformation harbored BRAFV600E mutation and seventeen of these had TERT promoter mutation. Unlike primary tumors with subsequent nodal anaplastic transformation, TERT promoter mutation was only present in the metastatic nodal recurrence from 4 patients without transformation. No patients had neither high-grade features (necrosis and increased mitotic activity) nor solid/insular growth or hobnail cell features in their primary tumors. In the group of patients with transformation, 3 had solid/insular growth in the lymph node metastasis at the time of primary tumor resection (one displaying nuclear features of PTC and solid growth with increased mitotic activity, one with insular component consistent with poorly differentiated carcinoma component, and one displaying nuclear features of PTC and solid growth), and additional 2 patients had solid/insular growth with no high-grade features or poorly differentiated carcinoma component at the time of subsequent nodal recurrence prior to anaplastic transformation. Hobnail cell features were exclusively seen in subsequent metastatic lymph nodes prior to anaplastic transformation. The control group lacked solid/insular growth and hobnail cell features in the metastatic nodal disease. Aberrant p53 expression and loss of TTF-1 featured tumor components with anaplastic transformation. This series identified a subset of recurrent PTCs with TERT promoter mutation was prone to undergo anaplastic transformation, and that solid/insular growth and hobnail cell features were morphological predictors of anaplastic transformation in the nodal recurrence.

Prevalence of BRAFV600E mutation in Asian series of papillary thyroid carcinoma-a contemporary systematic review.

Papillary thyroid carcinoma (PTC), the most common malignancy of the endocrine system, is frequently driven by BRAFV600E mutation, which was reported in 35-60% cases in Western series. Numerous studies have recently emerged from Asian countries and regions; however sufficient summary is lacking to date. BRAF mutation serves as a diagnostic and prognostic tool in thyroid cancer, therefore establishing a rate of BRAF on the national scale could be of practical significance. We performed systematic reviews of available literature to investigate the prevalence of BRAF mutation in series of PTC from various Asian countries and regions. Out of the total 3,966 reports identified via initial screening, 138 studies encompassing over 40,000 PTCs were included for the final analysis. A vast majority (90.2%) of PTCs with known BRAF status were from East Asia, including China, South Korea, and Japan, with BRAF mutation rates of 71.2%, 75.5%, and 70.6%, respectively. Less abundant Indian and Saudi Arabian series found 45.6% and 46.3% prevalence of BRAFV600E in PTC, respectively. Much limited evidence was available from Thailand, Iran, Kazakhstan, Taiwan, Singapore, Indonesia, Hong Kong, Philippines, Vietnam, Iraq, and Myanmar. No relevant publications were found from other highly populated countries, such as Pakistan, Bangladesh, and Malaysia. After grouping by geographic region, we found that the highest rate of BRAFV600E was reported in the PTC series from East Asia (76.4%). Much lower rate (45-48%) was seen in PTC cohorts from South Asia, Central Asia, and the Middle East while the Southeast Asian series were in between (57%). Further subgroup analysis revealed that studies employing fresh frozen tissue and fine-needle aspirates showed higher rates of BRAF compared to those used formalin-fixed paraffin-embedded tissues. We found that the PTC series enrolled patients' cohorts after 2010 demonstrated a higher rate of BRAF compared to the earlier series. Finally, pediatric PTCs had lower BRAF prevalence compared to the baseline rate for the country. In conclusion, despite considerable among and within countries heterogeneity, the Asian PTC series showed a higher prevalence of BRAFV600E mutation than that in Western series. Causes of geographic heterogeneity, whether genuine (etiology, genetics) or methodology-related should be further investigated.

Combinations of BRAF inhibitor and anti-PD-1/PD-L1 antibody improve survival and tumour immunity in an immunocompetent model of orthotopic murine anaplastic thyroid cancer

BackgroundPatients with anaplastic thyroid cancer (ATC) have an extremely poor prognosis despite aggressive multimodal therapy. ATC has a high prevalence of BRAFV600E mutations and is associated with an immunosuppressive microenvironment; we previously demonstrated that the combination of BRAF inhibitor and checkpoint inhibitor immunotherapy synergistically reduce tumour volume in an immunocompetent mouse model of orthotopic ATC.MethodsWe again utilised our mouse model of ATC to assess the combination of BRAFV600E inhibitor PLX4720 and anti-PD-L1 or anti-PD-1 antibody on survival, and performed immune cell profiling of lymphoid and myeloid-lineage cells during maximal treatment response and tumour regrowth.ResultsCombination therapy dramatically improved mouse survival. Maximal tumour reduction was associated with increases in the number and cytotoxicity of CD8+ T cells and NK cells, as well as increases in mostly M1-polarised tumour-associated macrophages (TAM) and decreases in myeloid-derived suppressor-like cells. Regrowth of tumour occurred after 2–3 weeks of ongoing combination therapy, and was most significantly associated with decreased TAMs and a dramatic increase in M2-polarisation.ConclusionsCombination of PLX4720 and anti-PD-L1/PD-1 antibody dramatically reduced tumour volume, prolonged survival and improved the anti-tumour immune profile in murine ATC. Tumour growth inevitably recurred and demonstrated re-emergence of an immunosuppressive tumour microenvironment.

Molecular Profiling of Papillary Thyroid Carcinoma in Korea with a High Prevalence of BRAFV600E Mutation.

The BRAFV600E mutation in papillary thyroid carcinoma (PTC) is particularly prevalent in Korea, and a considerable number of wild-type BRAF PTCs harbor RAS mutations. In addition, subsets of other genetic alterations clearly exist, but their prevalence in the Korean population has not been well studied. Recent increased insight into noninvasive encapsulated follicular variant PTC has prompted endocrine pathologists to reclassify this entity as "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" (NIFTP). This study analyzed the genetic alterations among the histologic variants of PTC, including NIFTP. Mutations of the BRAF and RAS genes and rearrangement of the RET/PTC1, NTRK1, and ALK genes using 769 preoperative fine-needle aspiration specimens and resected PTCs were analyzed. Molecular alterations were found in 687 (89.3%) of 769 PTCs. BRAFV600E mutation (80.8%) was the most frequent alteration, followed by RAS mutation and RET/PTC1, NTRK1, and ALK rearrangements (5.6%, 2.1%, 0.4%, and 0%, respectively). The low prevalence of NTRK1 fusions and the absence of an ALK fusion detected in Korea may also be attributed to the higher prevalence of the BRAFV600E mutation. There were significant differences in the frequency of the genetic alterations among the histologic variants of PTC. The prevalence of NIFTP in PTC was 2.7%, and among the NIFTPs, 28.6% and 57.1% harbored BRAF and RAS mutations, respectively. Clinicopathologic factors and mutational profiles between NIFTP and encapsulated follicular variant PTC with capsular invasion group were not significantly different. Genetic alterations in PTC vary among its different histologic variants and seem to be different in each ethnic group.

Molecular Profiles of Papillary Thyroid Tumors Have Been Changing in the Last Decades: How Could We Explain It?

The molecular profile of thyroid tumors can be discovered today in at least 70–80% of cases. The most common alterations are point mutations of BRAF and RAS followed by RET/PTC rearrangements. Other less frequent oncogenes involved are PIK3CA, TP53, TSHR, PTEN, GNAS, and CTNNB1 (1), but taken together they are still not able to account for 100% of cases. According to the data reported and collected so far (http://www.sanger.ac.uk/genetics/CGP/), BRAFV600E point mutations are present in about 45% of papillary thyroid cancer (PTC), with a higher rate in classical and tall cell variants and a rather low prevalence in follicular variant (2). There are exceptions with higher prevalence of BRAFV600E in PTC found in areas of China with a very high iodine content in the drinking water (3) and PTC found in the volcanic area of Mount Etna in Sicily where the drinking water is particularly rich in several elements, such as boron, iron, manganese, and vanadium, often present in concentrations exceeding usual maximum limits (4). The observations of Jung et al (5), showing a high prevalence of BRAFV600E mutation in a series of PTC diagnosed in the United States over a 35-year period, from 1974 to 2009, are of great relevance in this regard, associated with a significant increase of its prevalence in the classical variant of PTC over these last decades. The first study that indicated an increase of the prevalence of BRAFV600E mutation was reported in 2005 in a UK series, and the authors hypothesized that some environmental/etiological agent(s) could be responsible for the changing molecular features of PTC over time (6). Similar results were reported 6 years later by Mathur et al (7) in a series of PTC patients reported from California, and the hypothesis in this study was that the increased prevalence of the BRAFV600E mutation could be responsible for the increasing rate of PTC. In 2012, we also reported a significant increasing rate of BRAFV600E mutation in an Italian multicenter study (8), and it was interesting to observe that the increase was similar when the analysis was separately performed in the four different groups of PTC patients (from Pisa, Milan, Perugia, and Catania). Because the reported series are really very heterogeneous from a geographical point of view, it is conceivable that the increased prevalence of BRAFV600E mutation is a worldwide phenomenon, making it plausible that only a common, or very similar, reason could explain this trend. It is known that higher iodine intake has been found to be associated with a higher incidence of PTC (9), and it is notable that programs of iodine prophylaxis appear to be associated with an increase in the prevalence of PTC and a decrease in follicular histology (follicular thyroid cancer [FTC]) (10–12). This evidence and the Chinese report (3) may raise the question of a link between iodine intake, BRAFV600E mutation, and the development of increased incidence of PTC, but up to now, no experimental evidence that iodine can induce somatic gene alterations in follicular cells has been reported. Nevertheless, it is known that the iodine radical (I●), iodinium ion (I ) and the hypoiodous acid intermediate (IO[IOH]) are commonly formed in the follicular cell and represent reactive elements that together or as an alternative to H2O2 can determine cell oxidative stress, which is required to create conditions for thyroid cell proliferation (13–15). Further experimental studies on this putative relationship between

Bilaterality in Papillary Thyroid Carcinoma: Does It Influence Prognosis?

Papillary carcinoma is the most prevalent thyroid tumor subtype, and the incidence of this variant is rising in developed countries.1 The majority of papillary thyroid cancers (PTC) are indolent, and 5-year survival among those patients receiving appropriate surgical and medical therapy is greater than 95%. Nonetheless, a subgroup of PTCs will behave aggressively, and these tumors are associated with poorer overall and disease-free survival. Identification of specific disease characteristics correlating with prognosis has therefore become an important goal, both in understanding PTC biology and in directing therapeutic intervention. Historically, prognostic variables have included age, histopathological subtype, larger tumor size, and presence of extrathyroidal extension/metastasis.1,2 Multifocality is also an important feature of PTC. Multi-focal disease is common, being identified in 38% of micropapillary carcinoma cases, and is associated with tumor recurrence. The American Thyroid Association recommends using “clinical judgment” when considering whether radioactive iodine ablation (RAI) should be used to treat multifocal PTC, especially in light of recent studies showing that, for microscopic multifocal PTC, RAI does not improve recurrence rates.2,3 In addition, significant interest has recently developed in ascertaining the relationship between PTC prognosis and the presence of mutations in BRAF, a tyrosine kinase-encoding protooncogene commonly mutated in PTC cells.4–6 In this edition of The Annals of Surgical Oncology, Wang and colleagues consider whether bilaterality should be considered a new, potentially important prognostic feature of PTC. Interestingly, though both multifocality and bilaterality in PTC are traditionally considered indications for total or near-total thyroidectomy, few data specifically examining the prognostic implications of bilateral disease have been reported.7,8 In their manuscript “Poorer prognosis and higher prevalence of BRAFV600E mutation in synchronous bilateral papillary thyroid cancer,” Wang and colleagues detail the first formal evaluation of the relationship between bilaterality and prognosis in 891 PTC patients treated with total or near-total thyroidectomy over a 9-year period who were retrospectively identified. Bilateral synchronous PTC was defined as cancer diagnosed in both thyroid lobes at the same time or within a period of 3 months following removal of the first tumor. The authors found that bilateral PTC is common, occurring in 19.9% of their cohort, and that bilaterality is associated with poorer prognosis. Increased rates of extrathyroidal extension, nodal metastasis, as well as an overall higher stage at presentation were associated with bilateral disease. Further, these findings correlated with disease-free and overall survival, both of which decreased in the context of bilateral disease. Taken together, Wang and colleagues’ findings suggest that bilaterality is an important feature of PTC biology that may improve the clinician’s ability to predict the behavior of these tumors. Because mutation of the BRAF protooncogene is now recognized as a common genetic aberrancy contributing to the pathophysiology of PTC, evaluation for BRAF mutation may also be important in assessing the prognostic relevance of disease bilaterality. As such, the authors were able to assay BRAF gene sequences obtained from 208 consecutive patients, identifying a statistically significant increase in the prevalence of BRAF protooncogene mutations in bilateral versus unilateral cases (65.7 vs. 50.4%, P = 0.038). Nonetheless, these data must be interpreted carefully, as mutation of the BRAF protooncogene in the bilateral disease cohort did not correlate with other known prognostic features of PTC, including tumor size and extrathyroidal extension. The identification of tumor features associated with poor prognosis plays an important role in defining the pathophysiology of cancer and provides insight into the clinical management of malignancy. Here, Wang and colleagues provide initial data suggesting that disease bilaterality confers poor prognosis among patients diagnosed with PTC. Although data describing the prognostic relevance of multifocal PTC have been previously reported, this study represents the first published report to examine the prognostic relevance of bilateral disease. Potentially important correlations between disease bilaterality and tumor size, BRAF protooncogene mutation, extrathyroidal extension, and metastasis are supported by the authors’ findings. Future studies should be done prospectively, should detail tumor sizes in each lobe, and should normalize the performance and extent of neck dissection, as well as the use of postoperative 131I therapy. Analysis of histopathological subtypes among PTC patients having bilateral disease, relative to unilateral cases, may also provide insight into the prognostic value of bilaterality. Although Wang and colleagues provide an interesting initial study of the significance of bilateral disease in cases of papillary thyroid carcinoma, additional data will be required to validate bilaterality as an independent predictor of disease prognosis.

The Urokinase Plasminogen Activator System in Metastatic Papillary Thyroid Carcinoma: A Potential Therapeutic Target

Although distant metastases occur in a minority of papillary thyroid carcinoma (PTC) patients, their impact on disease course and survival rates is profound, with aggregate 10-yr survival rates of 40% (1). Limited treatment options further complicate management of metastatic PTC. Radioiodine (RAI) remains the standard of care for most distant metastases in PTC. Of particular concern, however, is the significant prevalence of PTC metastases unable to trap RAI; such metastases are termed RAI-refractory (RAIR). Because thyroid cancer loses differentiated features of normal thyroid tissue, one feature commonly lost is sodium iodide symporter expression, which is the entire basis for the use of RAI therapy in thyroid malignancies. This phenomenon can occur in a heterogeneous manner: in a given patient, RAI uptake can vary between individual metastases, and it can even vary within a metastasis at the cellular level.

Abstract 1970: Inhibition of BRAF-V600E increases melanocyte antigen expression and antigen-specific recognition in melanoma without altering T cell function

Abstract Given the high prevalence of BRAFV600E mutations in melanoma, targeted therapy against BRAF, or its mutated form, is a promising new therapeutic approach for patients with melanoma. Preliminary evidence suggests that BRAFV600E contributes to immune escape, and that blocking its activity via MAPK pathway inhibition leads to increased expression of melanocyte differentiation antigens, supporting the potential use of combination targeted therapy and immunotherapy. However, indiscriminate MAPK pathway inhibition may have deleterious effects on the immune system and lead to T cell dysfunction. The purpose of these studies was to explore the role of oncogenic BRAF in immune evasion by melanoma cells through its suppression of melanocyte differentiation antigens (MDAs). Furthermore, we sought to evaluate the effect of MAPK pathway inhibition on T lymphocyte function as a basis for combined targeted therapy and immunotherapy. Melanoma cell lines were cultured with MEK inhibitors (U0126, PD0325901) or a specific inhibitor of BRAFV600E (PLX4720) and expression of MDAs was assayed at the mRNA and protein level. The level of micro-opthalmia transcription factor (MITF), a transcriptional regulator of MDAs, was also assayed. Untreated and treated melanoma cell lines were co-cultured with antigen-specific T lymphocytes (generated by transduction of lymphocytes with MART-1- and gp100-specific T cell receptors) and reactivity was measured via interferon gamma release. The effect of MAPK pathway inhibition on T lymphocyte function was analyzed by assaying fold-expansion after OKT-3 & IL-2 stimulation as well as antigen-specific interferon gamma release. Inhibition of MAPK pathway in melanoma cell lines resulted in increased levels of MDAs which was associated with improved antigen-specific recognition by MART-1- and gp100-specific T lymphocytes. This was associated with higher intracellular levels of MITF. Treatment with MEK inhibitors resulted in impaired T lymphocyte function, as assayed by T cell expansion and antigen-specific interferon gamma release, whereas T cell function was preserved after treatment with a specific inhibitor of BRAFV600E. These findings suggest that oncogenic BRAF contributes to immune evasion by transcriptional repression of melanocyte antigen expression through MITF, which may be reversed by targeted MAPK pathway inhibition. Selective inhibition of BRAFV600E enhances MDA expression while preserving T cell function, whereas MEK inhibition has deleterious effects on T cell function. These data have important implications for the design of clinical trials using combined targeted therapy and immunotherapy for melanoma as well as other cancers. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1970.