Roderick J. Clifton-Bligh

Association Between BRAF V600E Mutation and Mortality in Patients With Papillary Thyroid Cancer

IMPORTANCE BRAF V600E is a prominent oncogene in papillary thyroid cancer (PTC), but its role in PTC-related patient mortality has not been established. OBJECTIVE To investigate the relationship between BRAF V600E mutation and PTC-related mortality. DESIGN, SETTING, AND PARTICIPANTS Retrospective study of 1849 patients (1411 women and 438 men) with a median age of 46 years (interquartile range, 34-58 years) and an overall median follow-up time of 33 months (interquartile range, 13-67 months) after initial treatment at 13 centers in 7 countries between 1978 and 2011. MAIN OUTCOMES AND MEASURES Patient deaths specifically caused by PTC. RESULTS Overall, mortality was 5.3% (45/845; 95% CI, 3.9%-7.1%) vs 1.1% (11/1004; 95% CI, 0.5%-2.0%) (P < .001) in BRAF V600E-positive vs mutation-negative patients. Deaths per 1000 person-years in the analysis of all PTC were 12.87 (95% CI, 9.61-17.24) vs 2.52 (95% CI, 1.40-4.55) in BRAF V600E-positive vs mutation-negative patients; the hazard ratio (HR) was 2.66 (95% CI, 1.30-5.43) after adjustment for age at diagnosis, sex, and medical center. Deaths per 1000 person-years in the analysis of the conventional variant of PTC were 11.80 (95% CI, 8.39-16.60) vs 2.25 (95% CI, 1.01-5.00) in BRAF V600E-positive vs mutation-negative patients; the adjusted HR was 3.53 (95% CI, 1.25-9.98). When lymph node metastasis, extrathyroidal invasion, and distant metastasis were also included in the model, the association of BRAF V600E with mortality for all PTC was no longer significant (HR, 1.21; 95% CI, 0.53-2.76). A higher BRAF V600E-associated patient mortality was also observed in several clinicopathological subcategories, but statistical significance was lost with adjustment for patient age, sex, and medical center. For example, in patients with lymph node metastasis, the deaths per 1000 person-years were 26.26 (95% CI, 19.18-35.94) vs 5.93 (95% CI, 2.96-11.86) in BRAF V600E-positive vs mutation-negative patients (unadjusted HR, 4.43 [95% CI, 2.06-9.51]; adjusted HR, 1.46 [95% CI, 0.62-3.47]). In patients with distant tumor metastasis, deaths per 1000 person-years were 87.72 (95% CI, 62.68-122.77) vs 32.28 (95% CI, 16.14-64.55) in BRAF V600E-positive vs mutation-negative patients (unadjusted HR, 2.63 [95% CI, 1.21-5.72]; adjusted HR, 0.84 [95% CI, 0.27-2.62]). CONCLUSIONS AND RELEVANCE In this retrospective multicenter study, the presence of the BRAF V600E mutation was significantly associated with increased cancer-related mortality among patients with PTC. Because overall mortality in PTC is low and the association was not independent of tumor features, how to use BRAF V600E to manage mortality risk in patients with PTC is unclear. These findings support further investigation of the prognostic and therapeutic implications of BRAF V600E status in PTC.

Mutation of the gene encoding human TTF-2 associated with thyroid agenesis, cleft palate and choanal atresia

Congenital hypothyroidism occurs in one of every three to four thousand newborns, owing to complete or partial failure of thyroid gland development. Although thyroid hypoplasia has recently been associated with mutations in the thyrotropin (TSH) receptor, the cause of thyroid agenesis is unknown. Proteins including thyroid transcription factors 1 (TTF-1; refs 4, 5) and 2 (TTF-2; refs 6, 7) and Pax8 (refs 8, 9) are abundant in the developing mouse thyroid and are known to regulate genes expressed during its differentiation (for example, thyroid peroxidase and thyroglobulin genes). TTF-2 is a member of the forkhead/winged-helix domain transcription factor family, many of which are key regulators of embryogenesis. Here we report that the transcription factor FKHL15 (ref. 11) is the human homologue of mouse TTF-2 (encoded by the Titf2 gene) and that two siblings with thyroid agenesis, cleft palate and choanal atresia are homozygous for a missense mutation (Ala65Val) within its forkhead domain. The mutant protein exhibits impaired DNA binding and loss of transcriptional function. Our observations represent the first description of a genetic cause for thyroid agenesis.

The roles of vitamin D in skeletal muscle: form, function, and metabolism.

Beyond its established role in bone and mineral homeostasis, there is emerging evidence that vitamin D exerts a range of effects in skeletal muscle. Reports of profound muscle weakness and changes in the muscle morphology of adults with vitamin D deficiency have long been described. These reports have been supplemented by numerous trials assessing the impact of vitamin D on muscle strength and mass and falls in predominantly elderly and deficient populations. At a basic level, animal models have confirmed that vitamin D deficiency and congenital aberrations in the vitamin D endocrine system may result in muscle weakness. To explain these effects, some molecular mechanisms by which vitamin D impacts on muscle cell differentiation, intracellular calcium handling, and genomic activity have been elucidated. There are also suggestions that vitamin D alters muscle metabolism, specifically its sensitivity to insulin, which is a pertinent feature in the pathophysiology of insulin resistance and type 2 diabetes. We will review the range of human clinical, animal, and cell studies that address the impact of vitamin D in skeletal muscle, and discuss the controversial issues. This is a vibrant field of research and one that continues to extend the frontiers of knowledge of vitamin Ds broad functional repertoire.

Association Between BRAF V600E Mutation and Recurrence of Papillary Thyroid Cancer

PURPOSE To investigate the prognostic value of BRAF V600E mutation for the recurrence of papillary thyroid cancer (PTC). PATIENTS AND METHODS This was a retrospective multicenter study of the relationship between BRAF V600E mutation and recurrence of PTC in 2,099 patients (1,615 women and 484 men), with a median age of 45 years (interquartile range [IQR], 34 to 58 years) and a median follow-up time of 36 months (IQR, 14 to 75 months). RESULTS The overall BRAF V600E mutation prevalence was 48.5% (1,017 of 2,099). PTC recurrence occurred in 20.9% (213 of 1,017) of BRAF V600E mutation-positive and 11.6% (125 of 1,082) of BRAF V600E mutation-negative patients. Recurrence rates were 47.71 (95% CI, 41.72 to 54.57) versus 26.03 (95% CI, 21.85 to 31.02) per 1,000 person-years in BRAF mutation-positive versus -negative patients (P < .001), with a hazard ratio (HR) of 1.82 (95% CI, 1.46 to 2.28), which remained significant in a multivariable model adjusting for patient sex and age at diagnosis, medical center, and various conventional pathologic factors. Significant association between BRAF mutation and PTC recurrence was also found in patients with conventionally low-risk disease stage I or II and micro-PTC and within various subtypes of PTC. For example, in BRAF mutation-positive versus -negative follicular-variant PTC, recurrence occurred in 21.3% (19 of 89) and 7.0% (24 of 342) of patients, respectively, with recurrence rates of 53.84 (95% CI, 34.34 to 84.40) versus 19.47 (95% CI, 13.05 to 29.04) per 1,000 person-years (P < .001) and an HR of 3.20 (95% CI, 1.46 to 7.02) after adjustment for clinicopathologic factors. BRAF mutation was associated with poorer recurrence-free probability in Kaplan-Meier survival analyses in various clinicopathologic categories. CONCLUSION This large multicenter study demonstrates an independent prognostic value of BRAF V600E mutation for PTC recurrence in various clinicopathologic categories.

miR-195 and miR-483-5p Identified as Predictors of Poor Prognosis in Adrenocortical Cancer

Purpose: Adrenocortical adenomas are common, whereas adrenocortical carcinomas are rare. Discriminating between benign and malignant adrenocortical tumors using conventional histology can be difficult. In addition, adrenocortical carcinomas generally have poor prognosis and limited treatment options. MicroRNAs are short noncoding RNAs that are involved in regulation of gene transcription. Experimental Design: To identify microRNAs involved in the pathogenesis of adrenocortical tumors, expression profiling of microRNAs was done on a cohort of 22 adrenocortical carcinomas, 27 adrenocortical adenomas, and 6 normal adrenal cortices. Results: Twenty-three microRNAs were found to be significantly differentially expressed between adrenocortical carcinomas and adrenocortical adenomas. miR-335 and miR-195 were significantly downregulated in adrenocortical carcinomas compared with adrenocortical adenomas. This result was further validated in an external cohort of six adrenocortical carcinomas and four adrenocortical adenomas. Using Kaplan-Meier analysis, downregulation of miR-195 and upregulation of miR-483-5p in adrenocortical carcinomas were significantly associated with poorer disease-specific survival. Conclusions: These findings indicate that deregulation of microRNAs is a recurring event in human adrenocortical carcinomas and that aberrant expression of miR-195 and miR-483-5p identifies a subset of poorer prognosis adrenocortical carcinomas. (Clin Cancer Res 2009;15(24):7684–92)

Immunohistochemistry for SDHB triages genetic testing of SDHB, SDHC, and SDHD in paraganglioma-pheochromocytoma syndromes.

Up to 30% of pheochromocytomas and paragangliomas are associated with germline RET, Von Hippel-Lindau (VHL), neurofibromatosis type I (NF1), and succinate dehydrogenase subunits (SDHB, SDHC, and SDHD) mutations. Genetic testing allows familial counseling and identifies subjects at high risk of malignancy (SDHB mutations) or significant multiorgan disease (RET, VHL, or NF1). However, conventional genetic testing for all loci is burdensome and costly. We performed immunohistochemistry for SDHB on 58 tumors with known SDH mutation status. We defined positive as granular cytoplasmic staining (a mitochondrial pattern), weak diffuse as a cytoplasmic blush lacking definite granularity, and negative as completely absent staining in the presence of an internal positive control. All 12 SDH mutated tumors (6 SDHB, 5 SDHD, and 1 SDHC) showed weak diffuse or negative staining. Nine of 10 tumors with known mutations of VHL, RET, or NF1 showed positive staining. One VHL associated tumor showed weak diffuse staining. Of 36 tumors without germline mutations, 34 showed positive staining. One paraganglioma with no known SDH mutation but clinical features suggesting familial disease was negative, and one showed weak diffuse staining. We also performed immunohistochemistry for SDHB on 143 consecutive unselected tumors of which 21 were weak diffuse or negative. As SDH mutations are virtually always germline, we conclude that approximately 15% of all pheochromocytomas or paragangliomas are associated with germline SDH mutation and that immunohistochemistry can be used to triage genetic testing. Completely absent staining is more commonly found with SDHB mutation, whereas weak diffuse staining often occurs with SDHD mutation.

Immunohistochemistry for SDHB divides gastrointestinal stromal tumors (GISTs) into 2 distinct types.

The Carney triad (CT) is gastrointestinal stromal tumor (GIST), paraganglioma, and pulmonary chondroma. The GISTs of CT show different clinical, molecular, and morphologic features to usual adult GISTs but are similar to the majority of pediatric GISTs. We postulated that these GISTs would show negative staining for succinate dehydrogenase B (SDHB). We performed SDHB immunohistochemistry on GISTs arising in 5 individuals with CT, 1 child, 7 individuals with GIST in young adulthood including 2 with germline KIT mutations, 3 individuals with neurofibromatosis 1, one 63-year-old female with multifocal gastric epithelioid GIST with lymph node metastases, and 104 consecutive unselected individuals with apparently sporadic GIST. The GISTs and paragangliomas arising in CT, the pediatric GIST, and the multifocal gastric GIST from the 63-year-old showed negative SDHB staining. GISTs from the 7 young adults and 3 with neurofibromatosis were SDHB positive. Of the unselected GISTs, 101 (97%) were positive. One of the negative GISTs arose in a 48-year-old female with previous recurrent multifocal gastric GISTs and the other 2 arose in females also in their 40s with gastric GISTs with epithelioid morphology. We conclude that negative staining for SDHB is characteristic of the GISTs of CT and the subgroup of pediatric GISTs which it resembles. Furthermore, when negative staining occurs in apparently sporadic GISTs in adults, the GISTs show morphologic and clinical features similar to pediatric and CT type GISTs. GISTs may therefore be divided into type 1 (SDHB positive) and type 2 (SDHB negative) subtypes.

Multikinase inhibitors: a new option for the treatment of thyroid cancer

Thyroid cancer typically has a good outcome following standard treatments, which include surgery, radioactive iodine ablation and treatment with TSH-suppressive levothyroxine. Thyroid cancers that persist or recur following these therapies have a poorer prognosis. Activation of mitogenic and angiogenic signaling pathways occurs in these cancers, and preclinical models have shown that inhibition of key kinase steps in these pathways can have antitumoral effects. Several of these kinase inhibitors have now been tested in phase II and phase III trials, with modestly encouraging results. Some promising data exist for the use of vandetanib (also known as ZD6474), motesanib, axitinib, cabozantinib (also known as XL184), sorafenib, sunitinib, pazopanib and lenvatinib (also known as E7080) in progressive thyroid cancer of medullary, papillary and follicular subtypes. These drugs are generally well-tolerated, although dose-limiting toxicities are common, and a few (probable) treatment-related deaths have been reported. Additional phase III trials will be needed to conclusively show that treatment benefit exceeds risk. Drug resistance can occur via activation of alternate mitogenic signals (pathway switching), as has been reported for the use of kinase inhibitors in other malignancies, such as melanoma. The hypothesis that combinations of kinase inhibitors targeting different pathways might produce better results is currently being tested in several clinical trials.

Low O6‐methylguanine‐DNA methyltransferase (MGMT) expression and response to temozolomide in aggressive pituitary tumours

Context  Recent case reports detail the successful use of temozolomide in the management of aggressive pituitary tumours. O6‐methylguanine‐DNA methyltransferase (MGMT) is a DNA repair protein that counteracts the effect of temozolomide.

Renal Tumors Associated With Germline Sdhb Mutation Show Distinctive Morphology

Germline succinate dehydrogenase B (SDHB) mutation causes pheochromocytoma/paraganglioma syndrome type 4 (PGL4). PGL4 is characterized by pheochromocytoma and paraganglioma, type 2 (SDHB negative) gastrointestinal stromal tumors and renal tumors, which are usually classified as carcinoma. We report 4 kindreds with 5 PGL4-associated renal tumors. Four of the tumors occurred before the age of 30 years, 4 were in the left kidney, 3 were in female patients, and 4 demonstrated consistent but previously unrecognized morphology. The tumors were composed of cuboidal cells with bubbly eosinophilic cytoplasm and indistinct cell borders. Many of the cells displayed distinctive cytoplasmic inclusions, which were vacuolated or contained eosinophilic fluid-like material. The cells were arranged in solid nests or in tubules surrounding central spaces. The tumors were well circumscribed or lobulated and frequently showed cystic change. Benign tubules or glomeruli were often entrapped at the edges of the tumors. The fifth tumor lacked these features but displayed sarcomatoid dedifferentiation. Immunohistochemistry for SDHB was completely negative in all 4 available tumors. Death from metastatic disease occurred in the patient with dedifferentiated tumor 1 year after diagnosis, whereas the other 4 tumors were cured by local excision alone (mean follow-up, 11 y; range, 2 to 30 y). We conclude that morphology supported by negative immunohistochemistry for SDHB can be used to identify kindreds with germline SDHB mutations (PGL4 syndrome) presenting with this unique type of renal tumor. These renal tumors appear to have a good prognosis after complete excision unless there is sarcomatoid dedifferentiation.