Publications by Year: 2015

Evaluation for malignancy of the adrenal cortex, adrenal cortical carcinoma (ACC), is a challenge in surgical pathology due to its relative rarity and histologic overlap with its benign counterpart, adrenocortical adenoma (ACA). We characterized a cohort of human ACC and ACA, including a molecular screen, with a goal of identifying potential diagnostic adjuncts. Thirty-six cases of ACC underwent histologic and clinical review. In the 31 ACC cases with available material and a cohort of 10 ACA cases, a multiplex nucleotide amplification molecular screen from formalin-fixed, paraffin-embedded tissue was peformed. ACCs demonstrated a wide variety of clinical and histologic characteristics with overall poor but unpredictable survival for subjects with ACC. By mutational screen, 12/31 (38.7%) carcinomas harbored CTNNB1 mutations, 1 with an additional TP53 mutation; 1 case each had isolated APC and TP53 mutations; 16 were wild-type for all tested loci; and 1 case demonstrated repeated assay failures. Two of the 10 ACA (20%) demonstrated CTNNB1 mutations by mutational screen, with no additional mutations. Immunohistochemistry for beta-catenin was performed and compared with the results of the molecular screen. Strong nuclear beta-catenin immunopositivity corresponded to the presence of CTNNB1 mutation by genotyping in 10 of 12 cases (83% sensitivity); the mismatched case(s) demonstrated strong membranous staining by immunohistochemistry. Seventeen of the 18 cases without CTNNB1 mutation showed membranous staining or did not stain (94% specificity); the mismatched case demonstrated scattered (<10%) positive nuclei. Both mutations in ACA were corroborated with immunohistochemistry for beta-catenin. No histomorphologic parameter appeared dominant in lesions with a particular mutational status. Based on these results, mutational status of CTNNB1 in adrenal cortical neoplasms can be predicted with reasonable accuracy by immunohistochemical cellular localization. Nuclear localization of beta-catenin by immunostain may be helpful in analysis of select lesions of the adrenal cortex whose biological behavior is uncertain from clinical and histologic information; a larger cohort is required to test this hypothesis.

CONTEXT: Anaplastic thyroid cancer (ATC) is the most lethal of all thyroid cancers and one of the most aggressive human carcinomas. In the search for effective treatment options, research toward targeted, personalized therapies is proving to be a path with great potential. As we gain a deeper understanding of the genetic (eg, BRAF(V600E), PIK3CA, TP53, hTERT mutations, etc) and epigenetic (eg, histone methylation, histone de-acetylation, microRNA regulatory circuits, etc) alterations driving ATC, we are able to find targets when developing novel therapies to improve the lives of patients. Beyond development, we can look into the effectiveness of already approved targeted therapies (eg, anti-BRAF(V600E) selective inhibitors, tyrosine kinase inhibitors, histone deacetylase inhibitors, inhibitors of DNA methylation, etc) to potentially test in ATC after learning the molecular mechanisms that aid in tumor progression.

DESIGN: We performed a literature analysis in Medline through the PubMed web site for studies published between 2003 and 2014 using the following main keywords: anaplastic thyroid cancer, genetic and epigenetic alterations.

OBJECTIVE: Here, we outlined the common pathways that are altered in ATC, including the BRAF(V600E)/ERK1/2-MEK1/2 and PI3K-AKT pathways. We then examined the current research looking into personalized, potential targeted therapies in ATC, mentioning those that have been tentatively advanced into clinical trials and those with the potential to reach that stage. We also reviewed side effects of the current and potential targeted therapies used in patients with advanced thyroid cancer.

CONCLUSIONS: DNA and RNA next-generation sequencing analysis will be fundamental to unraveling a precise medicine and therapy in patients with ATC. Indeed, given the deep biological heterogeneity/complexity and high histological grade of this malignancy and its tumor microenvironment, personalized therapeutic approaches possibly based on the use of combinatorial targeted therapy will provide a rational approach when finding the optimal way to improve treatments for patients with ATC.

BRAF(V600E) mutation exerts an essential oncogenic function in many tumors, including papillary thyroid carcinoma (PTC). Although BRAF(V600E) inhibitors are available, lack of response has been frequently observed. To study the mechanism underlying intrinsic resistance to the mutant BRAF(V600E) selective inhibitor vemurafenib, we established short-term primary cell cultures of human metastatic/recurrent BRAF(V600E)-PTC, intrathyroidal BRAF(V600E)-PTC, and normal thyroid (NT). We also generated an early intervention model of human BRAF(V600E)-PTC orthotopic mouse. We find that metastatic BRAF(V600E)-PTC cells elicit paracrine-signaling which trigger migration of pericytes, blood endothelial cells and lymphatic endothelial cells as compared to BRAF(WT)-PTC cells, and show a higher rate of invasion. We further show that vemurafenib therapy significantly suppresses these aberrant functions in non-metastatic BRAF(V600E)-PTC cells but lesser in metastatic BRAF(V600E)-PTC cells as compared to vehicle treatment. These results concur with similar folds of down-regulation of tumor microenvironment-associated pro-metastatic molecules, with no effects in BRAF(WT)-PTC and NT cells. Our early intervention preclinical trial shows that vemurafenib delays tumor growth in the orthotopic BRAF(WT/V600E)-PTC mice. Importantly, we identify high copy number gain of MCL1 (chromosome 1q) and loss of CDKN2A (P16, chromosome 9p) in metastatic BRAF(V600E)-PTC cells which are associated with resistance to vemurafenib treatment. Critically, we demonstrate that combined vemurafenib therapy with BCL2/MCL1 inhibitor increases metastatic BRAF(V600E)-PTC cell death and ameliorates response to vemurafenib treatment as compared to single agent treatment. In conclusion, short-term PTC and NT cultures offer a predictive model for evaluating therapeutic response in patients with PTC. Our PTC pre-clinical model suggests that combined targeted therapy might be an important therapeutic strategy for metastatic and refractory BRAF(V600E)-positive PTC.