Acute encephalopathy secondary to dabrafenib and trametinib in BRAF-positive metastatic adenocarcinoma of the lung

Acute encephalopathy secondary to targeted therapy with BRAF inhibitors is uncommon. There are few case reports in patients with metastatic melanoma who received treatment with dabrafenib and trametinib, and developed acute confusion. The encephalopathy appears to resolve after the discontinuation of offending drug, with patient returning to their baseline mentation and functional ability. The mechanism of the encephalopathy has been unclear. Unlike posterior reversible encephalopathy syndrome, which has been reported with vemurafenib and cobimetinib combination in melanoma patients, there are generally no acute imaging abnormalities observed (e.g. on computed tomography and magnetic resonance imaging brain scans). We report a case of acute encephalopathy in a patient with BRAF mutated metastatic lung cancer due to dabrafenib and trametinib treatment. With the increasing use of targeted therapies in lung cancer treatments, it is important for clinicians to be aware of potentially toxic effects of novel treatments.

Pathologic Characteristics, Natural History, and Prognostic Implications of BRAFV600E Mutation in Pediatric Papillary Thyroid Carcinoma

The BRAF^V600E mutation is the most common genetic aberration in papillary thyroid cancer (PTC), found in up to 68% of PTC in adults where it is associated with aggressive features. The incidence of this mutation in pediatric PTC is less frequent, reported as 0%-20% in the past and up to 63% in one recent series. Data suggest the mutation is not associated with an aggressive course in children; however, there are limited numbers of reported case series, so the prognostic implications remain poorly understood. The aim of this retrospective study was to examine the histologic characteristics and clinical outcomes of BRAF positive pediatric PTC at a single institution. A 12-year retrospective review of all thyroidectomies performed at a tertiary medical center identified 59 pediatric cases with a surgical pathology diagnosis of PTC. Fifty patients had BRAF^V600E mutation analysis data and were selected for further study. BRAF^V600E mutations were present in 48% of cases (n = 24) and absent in 52% (n = 26). The molecular characteristics of the BRAF negative cases will further be evaluated in future studies. BRAF positive cases occurred in patients who were on average older than the BRAF negative patients. Classic histology PTC was present in both BRAF positive and negative cases; however, only cases with classic PTC histology were positive for the mutation. No patients died and BRAF mutation was not associated with an increased recurrence rate. Our study supports BRAF^V600E is more common in children than previously thought and does not portend a more aggressive clinical course.

Immunohistochemistry with the anti-BRAF V600E (VE1) antibody: impact of pre-analytical conditions and concordance with DNA sequencing in colorectal and papillary thyroid carcinoma

Summary

The most common of all activating BRAF mutations (T1799A) leads to a substitution of valine (V) to glutamic acid (E) at the position 600 of the amino acid sequence. The major goal of this study was to compare detection of the BRAF V600E mutation by DNA sequencing with immunohistochemistry (IHC) using the anti-BRAF V600E (VE1) antibody. Archival formalin fixed, paraffin embedded tissues from 352 patients with colon adenocarcinoma (n = 279) and papillary thyroid carcinoma (n = 73) were evaluated for the BRAF V600E mutation by sequencing and IHC. The discordant cases were re-evaluated by repeat IHC, SNaPshot and next-generation sequencing (NGS). Furthermore, the effect of pre-analytical variables on the utility of this antibody was evaluated in two xenograft mouse models.

After resolving 15 initially discordant cases, 212 cases were negative for the BRAF V600E mutation by IHC. Of these, 210 cases (99.1%) were also negative by sequencing and two cases (0.9%) remained discordant. Of the 140 cases that were IHC positive for BRAF V600E, 138 cases were confirmed by sequencing (98.6%) and two cases remained discordant (1.4%). Overall, the negative predictive value was 99.1%, positive predictive value 98.6%, sensitivity 98.6%, specificity 99.1% and overall percentage agreement 98.9% (348/352 cases). Tissue fixation studies indicated that tissues should be fixed for 12–24 h within 2 h of tissue collection with 10% neutral buffered formalin.

Laryngeal Langerhans Cell Histiocytosis Presenting with Neck Mass in an Adult Woman

Langerhans cell histiocytosis (LCH) is a very rare condition that commonly affects the head and neck region. There are very few cases of isolated laryngeal involvement by LCH, mostly reported in pediatric patients. Here, we report a case of laryngeal LCH in a 62-year-old woman presenting with a neck mass several weeks ago. The clinical and histopathological findings are reported with a brief discussion about the disease.

Adrenal malignant melanoma masquerading as a pheochromocytoma in a patient with a history of a multifocal papillary and medullary thyroid carcinoma

OBJECTIVE

Adrenal masses usually represent benign and nonfunctional adrenal adenomas; however, primary or metastatic malignancy should also be considered. Discovery of an adrenal mass needs further evaluation in order to exclude malignancy and hormonal secretion. We present a rare case of a possibly primary adrenal malignant melanoma with imaging and biochemical features of a pheochromocytoma.

CASE REPORT

A 61-year-old male farmer was referred for evaluation of a mass in the right supraclavicular region and a left adrenal lesion. The patient had a history of a multifocal papillary and medullary thyroid carcinoma. Laboratory tests revealed increased 24hour urinary dopamine and also increased serum calcitonin and neuron specific enolase. A pathology report of the resected right supraclavicular mass and left adrenal showed a malignant melanoma.

CONCLUSION

This is a case of a possibly primary adrenal malignant melanoma with imaging and biochemical features of a pheochromocytoma. Although this case is very rare and there are rigid diagnostic criteria for the diagnosis of primary adrenal melanoma, it underlines the fact that the differential diagnosis of a dopamine secreting adrenal mass should include primary or metastatic malignant melanoma in order to determine the best diagnostic approach for the patient and select the most appropriate surgical management.

Mismatch repair deficiency testing in clinical practice

Lynch syndrome, an autosomal dominant inherited disorder, is caused by inactivating mutations involving DNA mismatch repair (MMR) genes. This leads to profound genetic instability, including microsatellite instability (MSI) and increased risk for cancer development, particularly colon and endometrial malignancies. Clinical testing of tumor tissues for the presence of MMR gene deficiency is standard practice in clinical oncology, with immunohistochemistry and PCR-based microsatellite instability analysis used as screening tests to identify potential Lynch syndrome families. The ultimate diagnosis of Lynch syndrome requires documentation of mutation within one of the four MMR genes (MLH1, PMS2, MSH2 and MSH6) or EPCAM, currently achieved by comprehensive sequencing analysis of germline DNA. In this review, the genetic basis of Lynch syndrome, methodologies of MMR deficiency testing, and current diagnostic algorithms in the clinical management of Lynch syndrome, are discussed.

BRAF mutations in non-small cell lung cancer: has finally Janus opened the door?

B-Raf mutations occur in about 1-2% of non-small cell lung cancers (NSCLC). These mutations generate a permanent activation of the mitogen activated protein kinase (MAPK) pathway, which promotes tumor growth and proliferation. In the present review, we discuss B-Raf mutation epidemiology, diagnostic methods to detect B-Raf mutations, the role of B-Raf as a driver mutation and a potential therapeutic target in NSCLC. The results of clinical trials involving B-Raf or MAPK pathway inhibitors for the treatment of NSCLC are also discussed. Clinical trials evaluating B-Raf inhibitors in BRAF mutated NSCLC patients have shown promising results, and larger prospective studies are warranted to validate these findings. Enrollment of these patients in clinical trials is an interesting strategy to offer a potentially more effective and less toxic targeted therapy.

Validation of a Manual Protocol for BRAF V600E Mutation-specific Immunohistochemistry

Detection of BRAF V600E has diagnostic, prognostic, and therapeutic relevance. The recently developed BRAF V600E mutation-specific antibody has evolved into a feasible alternative to DNA analysis. The plethora of immunohistochemical protocols makes implementation tedious and, here we tested a set of manual and automated protocols and compared test performance with sequencing results. For assays, we employed formalin-fixed, in part decalcified, and paraffin-embedded tissue samples. Empiric testing of manual protocols included 10 variables in 17 protocols. Automated immunohistochemical staining and BRAF pyrosequencing served as independent test methods. Test performance measures were compared without considering 1 method as a standard. Four well-fixed samples (2WT/2Mut) were used for testing of all protocols and indicated 2 correctly classifying procedures. Practical performance assessment employed 33 independent tissue samples, composed of 27 leukemias (by pyrosequencing: 8 wild-type; 18 mutated; 1 noninformative) and 6 melanomas (V600E; V600K; wild-type, 2 each). Manual V600E staining was positive in 20 cases (19 of 20 V600E-containing samples plus the 1 sample that was noninformative), whereas all wild-type and V600K cases were immunonegative. Manual or automated staining as well as pyrosequencing would have missed an equal number of V600E-mutated cases and the correlation coefficient for these methods was 0.75 to 0.93 (substantial to almost perfect); the Youden index was 0.95. Detection of V600E-mutated BRAF at the protein level in routine and decalcified tissue samples is possible, and the presented manual protocols should expedite implementation in routine diagnostic practice. Our results indicate that both molecular techniques should be considered complementary.

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.

Immunohistochemistry for BRAF V600E in the Differential Diagnosis of Hairy Cell Leukemia vs Other Splenic B-Cell Lymphomas

OBJECTIVES

Recent reports have used immunohistochemistry (IHC) with a mutation-specific antibody to detect the BRAF V600E mutation, which is found in nearly all cases of hairy cell leukemia (HCL). To date, however, only a small number of non-HCL, splenic B-cell lymphomas have been examined by IHC.

METHODS

We analyzed 121 cases, including 26 HCLs, 52 non-HCL splenic lymphomas, 22 chronic lymphocytic leukemias/small lymphocytic lymphomas (CLLs/SLLs), and 21 plasma cell neoplasms (PCNs) for BRAF V600E expression by IHC. Molecular testing for BRAF V600E was performed in a subset of cases, using allele-specific polymerase chain reaction and/or Sanger sequencing.

RESULTS

Twenty-six (100%) of 26 HCL cases were positive by IHC vs one (1%) of 95 non-HCL cases. Positive staining was identified in one (2%) of 44 splenic marginal zone lymphomas (SMZLs), while each of 22 CLLs/SLLs, 21 PCNs, six unclassifiable splenic lymphomas, and two HCL variants were negative. IHC and molecular results were concordant in all cases examined (21 HCLs and 21 non-HCLs, including the BRAF+ SMZLs).

CONCLUSIONS

The detection of BRAF V600E by IHC is useful in the distinction of HCLs from other splenic-based lymphomas, although the identification of at least rare SMZLs containing this abnormality illustrates the continuing need for a multiparameter approach to diagnosis.

KRAS mutation testing in clinical practice

Activating mutation of KRAS plays a significant role in the pathogenesis of common human malignancies and molecular testing of KRAS mutation has emerged as an essential biomarker in the current practice of clinical oncology. The presence of KRAS mutation is generally associated with clinical aggressiveness of the cancer and reduced survival of the patient. Therapeutically, KRAS mutation testing has maximum utility in stratifying metastatic colorectal carcinoma and lung cancer patients for treatment with targeted therapy. Diagnostically, KRAS mutation testing is useful in the workup of pancreaticobiliary and thyroid cancers, particularly using cytological specimens. In the era of precision medicine, the role of KRAS mutation testing is poised to expand, likely in a setting of combinatorial therapeutic strategy and requiring additional mutation testing of its upstream and/or downstream effectors.

Best practice of BRAF V600E mutation testing for the diagnosis and management of thyroid cancers

BRAF V600E mutation is the single most common genetic alteration identified in papillary thyroid carcinoma. There is significant association between BRAF V600E mutation and aggressive tumor behavior. BRAF V600E mutation has also been found to be an independent predictor of treatment failure and tumor recurrence even in patients with low-stage disease. Pre-operative BRAF mutation testing of thyroid fine needle aspiration specimens has become a routine clinical practice that enhances the predictability of malignancy in indeterminate fine needle aspiration cytology specimens especially those in the follicular lesion of undetermined significance/atypia of undetermined significance category. In addition to histological evaluation of subsequent core needle biopsy and BRAF immunohistochemistry, an expanded panel of mutation testing including BRAF V600E, NRAS, HRAS, RET/papillary thyroid carcinoma and PAX8/PPARγ rearrangements are currently advocated to further improve the diagnostic predictability in the detection of thyroid carcinomas using cytological specimens.

BRAF gene: From human cancers to developmental syndromes

The BRAF gene encodes for a serine/threonine protein kinase that participates in the MAPK/ERK signalling pathway and plays a vital role in cancers and developmental syndromes (RASopathies). The current review discusses the clinical significance of the BRAF gene and other members of RAS/RAF cascade in human cancers and RAS/MAPK syndromes, and focuses the molecular basis and clinical genetics of BRAF to better understand its parallel involvement in both tumourigenesis and RAS/MAPK syndromes—Noonan syndrome, cardio-facio-cutaneous syndrome and LEOPARD syndrome.

Implementation of a companion diagnostic in the clinical laboratory: the BRAF example in melanoma

A companion diagnostic test provides information that is essential for the safe and effective use of a corresponding therapeutic product as indicated in the drug instructions. The implementation of a companion diagnostic follows the rules of a molecular test for somatic mutations in a routine clinical laboratory environment and needs guidance on practical aspects, including the choice of the proper analytical method and the procedures for internal and external quality controls. Selection of the appropriate assay for detection of genetic alterations depends on several factors: the type of mutation under study, the sample to be assayed and its preparation procedure. In addition, the results of a molecular assay require a complex interpretation process of the analytical data as the patient's genotype, the translation of the identified variant into a predicted phenotype and knowledge on restrictions of the method used. In relation to these aspects herein we report an opinion paper of the Working Group Personalized Laboratory Medicine jointly constituted by the European Federation of Laboratory Medicine (EFLM) and by the European Society of Pharmacogenomics and Theranostics (ESPT) using, as an example, the BRAF genotype analysis in tumor tissue samples for identification of melanoma patients that can benefit treatment with BRAF inhibitors. The manuscript is focused on the following aspects: i) medical rationale, ii) methodologies of analysis, iii) laboratory performance evaluation and iv) the laboratory specific report for the clinicians. The critical evaluation of these aspects would be useful for the implementation of a companion diagnostic in the clinical laboratory.

Preappointment testing for BRAF/KIT mutation in advanced melanoma: a model in molecular data delivery for individualized medicine

The emergence of individualized medicine is driven by developments in precision diagnostics, epitomized by molecular testing. Because treatment decisions are being made based on such molecular data, data management is gaining major importance. Among data management challenges, creating workflow solutions for timely delivery of molecular data has become pivotal. This study aims to design and implement a scalable process that permits preappointment BRAF/KIT mutation analysis in melanoma patients, allowing molecular results necessary for treatment plans to be available before the patient's appointment. Process implementation aims to provide a model for efficient molecular data delivery for individualized medicine. We examined the existing process of BRAF/KIT testing in melanoma patients visiting our institution for oncology consultation. We created 5 working groups, each designing a specific segment of an alternative process that would allow preappointment BRAF/KIT testing and delivery of results. Data were captured and analyzed to evaluate the success of the alternative process. For 1 year, 35 (59%) of 55 patients had prior BRAF/KIT testing. The remaining 20 patients went through the new process of preappointment testing; results were available at the time of appointment for 12 patients (overall preappointment results availability, 85.5%). The overall process averaged 13.4 ± 4.7 days. In conclusion, we describe the successful implementation of a scalable workflow solution that permits preappointment BRAF/KIT mutation analysis and result delivery in melanoma patients. This sets the stage for further applications of this model to other conditions, answering an increasing demand for robust delivery of molecular data for individualized medicine.

Langerhans cell sarcoma: case report and review of world literature

Langerhans cell sarcoma is a rare malignancy with only 1 pediatric case (less than 15 y of age) reported. Here, we report the second case of Langerhans cell sarcoma in a child who presented with cord compression. This patient was treated with extensive surgical resection, postoperative chemotherapy, and involved-field radiation therapy. She completed therapy and remains in remission for 27 months. A review and analysis of all 53 cases published in the world literature is provided to help guide physicians treating this disease. Recently discovered genetic mutation involving BRAF is also discussed.

Consensus guidelines for the diagnosis and clinical management of Erdheim-Chester disease

Erdheim-Chester disease (ECD) is a rare, non-Langerhans histiocytosis. Recent findings suggest that ECD is a clonal disorder, marked by recurrent BRAFV600E mutations in >50% of patients, in which chronic uncontrolled inflammation is an important mediator of disease pathogenesis. Although ∼500 to 550 cases have been described in the literature to date, increased physician awareness has driven a dramatic increase in ECD diagnoses over the last decade. ECD frequently involves multiple organ systems and has historically lacked effective therapies. Given the protean clinical manifestations and the lack of a consensus-derived approach for the management of ECD, we provide here the first multidisciplinary consensus guidelines for the clinical management of ECD. These recommendations were outlined at the First International Medical Symposium for ECD, comprised of a comprehensive group of international academicians with expertise in the pathophysiology and therapy of ECD. Detailed recommendations on the initial clinical, laboratory, and radiographic assessment of ECD patients are presented in addition to treatment recommendations based on critical appraisal of the literature and clinical experience. These formalized consensus descriptions will hopefully facilitate ongoing and future research efforts in this disorder.

The BRAF V600E mutation in papillary thyroid cancer with positive or suspected pre-surgical cytological finding is not associated with advanced stages or worse prognosis

The mutation BRAF V600E is thought to be a putative prognostic marker of the aggressiveness of several cancers among which is also papillary thyroid cancer. Our study aimed to evaluate whether this mutation is associated with advanced stages of disease or with a worse prognosis in a series of patients with cytological findings of Thyr 4 and Thyr 5 and who were undergoing total thyroidectomy and routine central compartment lymph-node dissection. 110 patients were consecutively enrolled over an 18-month period from September 2010 to March 2012. All patients had cytological findings that were either indicative of, or positive for papillary thyroid cancer, Thyr 4 or Thyr 5. Detection of BRAF mutation was made on fine-needle aspiration specimen by pyrosequencing after microdissection and DNA extraction of neoplastic cells. After surgical intervention, the patients underwent radioiodine ablation according to our protocol, and follow-up was performed after 8 months. The BRAF V600E mutation was found in 79 % of our cases: 85.7 % of these cases represented the classical variant, 57.8 % the follicular variant, 89.6 % the tall cell variant, and 33.3 % the solid variant. All patients had confirmation of papillary thyroid cancer after histology, with no differences being seen in pTNM presentation between patients with BRAF wild-type and patients with BRAF V600E mutation. Ninety-nine patients underwent radioiodine ablation. Results at follow-up 8 months after radioiodine ablation showed no differences in the rate of ablation between patients harboring BRAF V600E mutation and those having BRAF wild-type. The BRAF V600E mutation doesn't appear to be a reliable risk factor for the aggressiveness of a tumor. BRAF analysis should neither be the only guide for pre-surgical decisions regarding the extent of surgery nor for post-surgical decisions regarding the aggressiveness of the treatment.

High-resolution melting analysis for accurate detection of BRAF mutations: a systematic review and meta-analysis

The high-resolution melting curve analysis (HRMA) might be a good alternative method for rapid detection of BRAF mutations. However, the accuracy of HRMA in detection of BRAF mutations has not been systematically evaluated. We performed a systematic review and meta-analysis involving 1324 samples from 14 separate studies. The overall sensitivity of HRMA was 0.99 (95% confidence interval (CI) = 0.75–0.82), and the overall specificity was very high at 0.99 (95% CI = 0.94–0.98). The values for the pooled positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 68.01 (95% CI = 25.33–182.64), 0.06 (95% CI = 0.03–0.11), and1263.76 (95% CI = 393.91–4064.39), respectively. The summary receiver operating characteristic curve for the same data shows an area of 1.00 and a Q* value of 0.97. The high sensitivity and specificity, simplicity, low cost, less labor or time and rapid turnaround make HRMA a good alternative method for rapid detection of BRAF mutations in the clinical practice.

BRAF V600E mutation analysis simplifies the testing algorithm for Lynch syndrome

OBJECTIVES

To evaluate our experience of adding reflex BRAF mutation analysis following mismatch repair (MMR) protein staining in the test algorithm for Lynch syndrome (LS), the most common inherited predisposition to colorectal cancer (CRC).

METHODS

Since January 1, 2009, BRAF V600E mutation analysis has been performed at our institution for all newly diagnosed CRCs with absent MLH1 and PMS2 proteins.

RESULTS

Ninety (22%) of 412 patients with CRC had at least 1 MMR absent (65 had MLH1 and PMS2 absent and 25 had other stain(s) absent). BRAF mutation was found in 36 (55%) of 65. Fifty-four (13%) of 412 patients required follow-up after addition of BRAF analysis compared with 90 who would have required follow-up without BRAF analysis.

CONCLUSIONS

The addition of reflex BRAF mutation testing in CRCs with absent MLH1 and PMS2 reduced the number of patient contacts by 40% and simplified the genetic testing for LS, leading to cost and time savings.

The diagnostic role and clinical relevance of determination of BRAF status in brain tumors

BRAF protein is a serine/threonine kinase that serves as an immediate downstream effector of the MAPK signaling cascade, a signal transduction pathway that modulates cell proliferation and survival. BRAF alterations leading to MAPK pathway activation have been identified in gliomas and glioneuronal tumors of the CNS. Whereas BRAF mutations have been found in a wide spectrum of CNS tumors, BRAF fusions have been almost exclusively found in pilocytic astrocytomas. BRAF fusion identification provides an additional help in the differential diagnosis of supratentorial gliomas. Although the prognostic significance of BRAF alterations in different CNS tumors is still under investigation, the evidence of BRAF-dependent MAPK-pathway activation in gliomas has moreover drawn attention to the potential use of MEK1/2 and RAF inhibitors in clinical neuro-oncology. Given the promising results of the therapeutic management of several cancer types, clinical studies investigating the suitability of such inhibitors for the therapy of gliomas are ongoing.

B-Raf and the inhibitors: from bench to bedside

The B-Raf protein is a key signaling molecule in the mitogen activated protein kinase (MAPK) signaling pathway and has been implicated in the pathogenesis of a variety of cancers. An important V600E mutation has been identified and can cause constitutive B-Raf activation. Recent studies have evaluated a variety of small molecule inhibitors targeting B-Raf, including PLX4032/vemurafenib, dabrafenib, LGX818, GDC0879, XL281, ARQ736, PLX3603 (RO5212054), and RAF265. Therapeutic resistance has been identified and various mechanisms described. This review also discussed the current understanding of B-Raf signaling mechanism, methods of mutation detection, treatment strategies as well as potential methods of overcoming therapeutic resistance.

Comparison of testing methods for the detection of BRAF V600E mutations in malignant melanoma: pre-approval validation study of the companion diagnostic test for vemurafenib

Background

The cobas 4800 BRAF V600 Mutation Test is a CE-marked and FDA-approved in vitro diagnostic assay used to select patients with metastatic melanoma for treatment with the selective BRAF inhibitor vemurafenib. We describe the pre-approval validation of this test in two external laboratories.

Methods

Melanoma specimens were tested for BRAF V600 mutations at two laboratories with the: cobas BRAF Mutation Test; ABI BRAF test; and bidirectional direct sequencing. Positive (PPA) and negative (NPA) percent agreements were determined between the cobas test and the other assays. Specimens with discordant results were tested with massively parallel pyrosequencing (454). DNA blends with 5% mutant alleles were tested to assess detection rates.

Results

Invalid results were observed in 8/116 specimens (6·9%) with Sanger, 10/116 (8·6%) with ABI BRAF, and 0/232 (0%) with the cobas BRAF test. PPA was 97·7% for V600E mutation for the cobas BRAF test and Sanger, and NPA was 95·3%. For the cobas BRAF test and ABI BRAF, PPA was 71·9% and NPA 83·7%. For 16 cobas BRAF test-negative/ABI BRAF-positive specimens, 454 sequencing detected no codon 600 mutations in 12 and variant codon 600 mutations in four. For eight cobas BRAF test-positive/ABI BRAF-negative specimens, four were V600E and four V600K by 454 sequencing. Detection rates for 5% mutation blends were 100% for the cobas BRAF test, 33% for Sanger, and 21% for the ABI BRAF. Reproducibility of the cobas BRAF test was 111/116 (96%) between the two sites.

Conclusions

It is feasible to evaluate potential companion diagnostic tests in external laboratories simultaneously to the pivotal clinical trial validation. The health authority approved assay had substantially better performance characteristics than the two other methods. The overall success of the cobas BRAF test is a proof of concept for future biomarker development.

BRAFV600E mutation in papillary thyroid microcarcinoma: a genotype-phenotype correlation

BRAF(V600E) mutation has emerged as a marker of aggressive behavior in papillary thyroid carcinoma but its significance in microcarcinoma is not entirely clear. One-hundred and twenty-nine papillary thyroid microcarcinomas were tested for BRAF(V600E) mutation by single-strand conformation polymorphism, and their clinicopathologic features (age, sex, tumor size, multifocality, nodal metastases, histologic subtype, tumor cell morphology, architecture, tumor-associated stromal reaction, tumor interface to non-neoplastic thyroid (well circumscribed vs infiltrative), extrathyroidal extension, lymphovascular invasion, intratumoral multinucleated giant cells, and adjacent non-neoplastic thyroid pathology) were examined. Compared with tumors without the mutation (39/129, 30%), the mutated microcarcinomas (90/129, 70%) showed significantly higher prevalence of infiltrative tumor borders (78/90 vs 23/39, P=0.001), tumor-associated stromal desmoplasia/fibrosis and/or sclerosis (80/90 vs 25/39, P=0.002), classic nuclear features of papillary thyroid carcinoma (90/90 vs 35/39, P=0.008) and cystic change (43/90 vs 11/39, P=0.05). BRAF(V600E) mutation was more frequent in classic (75%), tall cell (91%), and other variants (>70%) than in follicular variant (21%) of papillary thyroid microcarcinoma. Tumors without the mutation were significantly more likely to be solid, well circumscribed, and lacked desmoplasia/fibrosis or sclerosis. However, on multivariate analysis, only the follicular variant of papillary microcarcinoma was significantly associated with the absence of mutation (odds ratio (95% confidence interval): 0.09 (0.01-0.54)). Lymph node metastases (n=24) were more frequent in microcarcinomas with mutation than without (21/24 vs 3/24, P=0.02). All patients with lateral cervical node metastasis (n=9), and all but one tumor with extrathyroidal extension (n=17/18) showed BRAF(V600E) mutation. No significant differences were noted in age, sex, tumor size, multifocality, lymphovascular invasion, psammoma bodies, stromal calcification, intratumoral multinucleated osteoclastic-type giant cells, and lymphocytic infiltration between the two groups of tumors. BRAF(V600E) mutation is an early event in thyroid carcinogenesis, and is associated with distinctive morphology and aggressive features even in papillary thyroid microcarcinomas.