Hyeong Ju Kwon

Phase II clinical and exploratory biomarker study of dacomitinib in patients with recurrent and/or metastatic squamous cell carcinoma of head and neck.

Purpose: The goals of this study were to investigate the clinical activity, safety, and biomarkers of dacomitinib, an irreversible tyrosine kinase inhibitor of EGFR, HER2, and HER4, in recurrent and/or metastatic squamous cell carcinoma of the head and neck (R/M-SCCHN). Experimental Design: Patients were eligible if the diseases were not amenable to curative treatment and had progressed on platinum-based chemotherapy, and were treated with dacomitinib 45 mg/day. The primary endpoint was objective response rate by RECISTv1.1. Exploratory analysis included the characterization of somatic mutation, gene copy number, gene expression, p16INK4A expression by IHC, and investigation of their relationship with clinical outcomes. Results: Forty-eight patients were evaluable for efficacy and toxicity. Ten patients (20.8%) had partial responses and 31 patients (65%) had stable diseases. The median progression-free survival (PFS) and overall survival (OS) were 3.9 months [95% confidence interval (CI), 2.9–5.0] and 6.6 months (95% CI, 5.4–10.3). Adverse events were mostly grade 1–2. Mutations in the PI3K pathway (PIK3CA, PTEN) and high expression of inflammatory cytokines (IL6, IL8, IL1A, IL1B, IL4, and TNF) were significantly associated with shorter PFS (2.9 vs. 4.9 months without mutations, P = 0.013; 2.8 vs. 9.9 months with low expression, P = 0.004). Those harboring PI3K pathway mutations or high inflammatory cytokine expression had shorter median OS (6.1 vs. 12.5 months lacking PI3K pathway mutations and with low inflammatory cytokine expression, P = 0.005). Conclusions: Dacomitinib demonstrated clinical efficacy with manageable toxicity in platinum-failed R/M-SCCHN patients. Screening of PI3K pathway mutation and inflammatory cytokine expression may help identify which R/M-SCCHN patients are likely to gain benefit from dacomitinib. Clin Cancer Res; 21(3); 544–52. ©2014 AACR.

Hypoxia Induces Epithelial-Mesenchymal Transition in Follicular Thyroid Cancer: Involvement of Regulation of Twist by Hypoxia Inducible Factor-1α.

Purpose Although follicular thyroid cancer (FTC) has a relatively fair prognosis, distant metastasis sometimes results in poor prognosis and survival. There is little understanding of the mechanisms contributing to the aggressiveness potential of thyroid cancer. We showed that hypoxia inducible factor-1α (HIF-1α) induced aggressiveness in FTC cells and identified the underlying mechanism of the HIF-1α-induced invasive characteristics. Materials and Methods Cells were cultured under controlled hypoxic environments (1% O2) or normoxic conditions. The effect of hypoxia on HIF-1α, and epithelial-to-mesenchymal transition (EMT) related markers were evaluated by quantitative real-time PCR, Western blot analysis and immunocytochemistry. Invasion and wound healing assay were conducted to identify functional character of EMT. The involvement of HIF-1α and Twist in EMT were studied using gene overexpression or silencing. After orthotopic nude mouse model was established using the cells transfected with lentiviral shHIF-1α, tissue analysis was done. Results Hypoxia induces HIF-1α expression and EMT, including typical morphologic changes, cadherin shift, and increased vimentin expression. We showed that overexpression of HIF-1α via transfection resulted in the aforementioned changes without hypoxia, and repression of HIF-1α with RNA interference suppressed hypoxia-induced HIF-1α and EMT. Furthermore, we also observed that Twist expression was regulated by HIF-1α. These were confirmed in the orthotopic FTC model. Conclusion Hypoxia induced HIF-1α, which in turn induced EMT, resulting in the increased capacity for invasion and migration of cells via regulation of the Twist signal pathway in FTC cells. These findings provide insight into a possible therapeutic strategy to prevent invasive and metastatic FTC.

The follicular variant of papillary thyroid carcinoma: characteristics of preoperative ultrasonography and cytology

Purpose: The goal of this study was to validate the ultrasonography (US) and cytopathological features that are used in the diagnosis of the follicular variant of papillary thyroid carcinoma (FVPTC) and to characterize the role of BRAFV600E mutation analysis in the diagnosis of FVPTC. Methods: From May 2012 to February 2014, 40 thyroid nodules from 40 patients (mean age, 56.2 years; range, 26 to 81 years) diagnosed with FVPTC were included in this study. The US features of the nodules were analyzed and the nodules were classified as probably benign or suspicious for malignancy. Twenty-three thyroid nodules (57.5%) underwent BRAFV600E mutation analysis. Clinical information and histopathologic results were obtained by reviewing the medical records of the patients. Results: Thirty nodules (75.0%) were classified as suspicious for malignancy, while 10 (25.0%) were classified as probably benign. Seven of the eight nodules (87.5%) with atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS) cytology showed suspicious US features, while one of the two nodules (50.0%) with follicular neoplasm cytology presented suspicious US features. Five of the 23 nodules (21.7%) that underwent BRAFV600E mutation analysis had positive results, all of which were diagnosed as suspicious for malignancy or malignant based on cytology. None of the nodules with benign, AUS/FLUS, or follicular neoplasm cytology were positive for the BRAFV600E mutation. Conclusion: US features allow nodules to be classified as suspicious for malignancy, and the presence of suspicious US features in nodules with ambiguous cytology may aid in the diagnosis of FVPTC. BRAFV600E mutation analysis is of limited value in the diagnosis of FVPTC.

The use of the Bethesda system for reporting thyroid cytopathology in Korea: A nationwide multicenter survey by the Korean society of endocrine pathologists

Background The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) has standardized the reporting of thyroid cytology specimens. The objective of the current study was to evaluate the nationwide usage of TBSRTC and assess the malignancy rates in each category of TBSRTC in Korea. Methods Questionnaire surveys were used for data collection on the fine needle aspiration (FNA) of thyroid nodules at 74 institutes in 2012. The incidences and follow-up malignancy rates of each category diagnosed from January to December, 2011, in each institute were also collected and analyzed. Results Sixty out of 74 institutes answering the surveys reported the results of thyroid FNA in accordance with TBSRTC. The average malignancy rates for resected cases in 15 institutes were as follows: nondiagnostic, 45.6%; benign, 16.5%; atypical of undetermined significance, 68.8%; suspicious for follicular neoplasm (SFN), 30.2%; suspicious for malignancy, 97.5%; malignancy, 99.7%. Conclusions More than 80% of Korean institutes were using TBSRTC as of 2012. All malignancy rates other than the SFN and malignancy categories were higher than those reported by other countries. Therefore, the guidelines for treating patients with thyroid nodules in Korea should be revisited based on the malignancy rates reported in this study.

c-Met-mediated reactivation of PI3K/AKT signaling contributes to insensitivity of BRAF(V600E) mutant thyroid cancer to BRAF inhibition.

BRAF (V600E) mutation is the most commonly detected genetic alteration in thyroid cancer. Unlike its high treatment response to selective BRAF inhibitor (PLX4032) in metastatic melanoma, the treatment response in thyroid cancer is reported to be low. The purpose of this study is to investigate the resistance mechanism responsible for this low treatment response to BRAF inhibitor in order to maximize the effect of targeted therapy. We examined the expression of feedback regulation mechanisms and alterations in the upper signal transduction pathway in thyroid cancer cell lines harboring BRAF mutation. Also, we investigated the effect of dual inhibition from combinatorial therapy. Two thyroid cancer cell lines, 8505C (anaplastic thyroid cancer) and BCPAP (papillary thyroid cancer) were selected and treated with PLX4032 and its drug sensitivity were examined and compared. Further investigation on the changes in signals responsible for the different treatment response to PLX4032 was carried out and the same experiment was performed on orthotopic xenograft mouse models. Unlike BCPAP cells, 8505C cells presented drug resistance to PLX4032 treatment and this was mainly due to increased expression of c‐Met. Effective inhibitions of c‐Met, p‐AKT, and p‐ERK were achieved after dual treatment with BRAF inhibitor (PLX4032) and c‐Met inhibitor (PHA665752). Similar results were confirmed by in vivo study with orthotopic xenograft mouse model. c‐Met‐mediated reactivation of the PI3K/AKT pathway and MAPK pathway contributes to the relative insensitivity of BRAF (V600E) mutant anaplastic thyroid cancer cells to PLX4032. Dual inhibition of BRAF and c‐Met leads to sustained treatment response.

Exome sequencing reveals recurrent REV3L mutations in cisplatin-resistant squamous cell carcinoma of head and neck

Dacomitinib, an irreversible pan-HER inhibitor, had shown modest clinical activity in squamous cell carcinoma of head and neck (SCCHN) patients. Therefore, validated predictive biomarkers are required to identify patients most likely to benefit from this therapeutic option. To characterize the genetic landscape of cisplatin-treated SCCHN genomes and identify potential predictive biomarkers for dacomitinib sensitivity, we performed whole exome sequencing on 18 cisplatin-resistant metastatic SCCHN tumors and their matched germline DNA. Platinum-based chemotherapy elevated the mutation rates of SCCHN compared to chemotherapy-naïve SCCHNs. Cisplatin-treated SCCHN genomes uniquely exhibited a novel mutational signature characterized by C:G to A:T transversions at CCR sequence contexts that may have arisen due to error-prone translesional synthesis. Somatic mutations in REV3L, the gene encoding the catalytic subunit of DNA polymerase ζ involved in translesional synthesis, are significantly enriched in a subset of patients who derived extended clinical benefit to dacomitinib (P = 0.04). Functional assays showed that loss-of-function of REV3L dramatically enhanced the sensitivity of SCCHN cells to dacomitinib by the loss of both translesion synthesis and homologous recombination pathways. Our data suggest that the ‘platinum’ mutational signature and inactivation of REV3L may inform treatment options in patients of recurrent SCCHN.

Histogram and gray level co-occurrence matrix on gray-scale ultrasound images for diagnosing lymphocytic thyroiditis

The objective of the study was to evaluate whether texture analysis using histogram and gray level co-occurrence matrix (GLCM) parameters can help clinicians diagnose lymphocytic thyroiditis (LT) and differentiate LT according to pathologic grade. The background thyroid pathology of 441 patients was classified into no evidence of LT, chronic LT (CLT), and Hashimotos thyroiditis (HT). Histogram and GLCM parameters were extracted from the regions of interest on ultrasound. The diagnostic performances of the parameters for diagnosing and differentiating LT were calculated. Of the histogram and GLCM parameters, the mean on histogram had the highest Az (0.63) and VUS (0.303). As the degrees of LT increased, the mean decreased and the standard deviation and entropy increased. The mean on histogram from gray-scale ultrasound showed the best diagnostic performance as a single parameter in differentiating LT according to pathologic grade as well as in diagnosing LT.

Thyroid Fine-Needle Aspiration Cytology Practice in Korea

We reviewed the current status of thyroid fine-needle aspiration cytology (FNAC) in Korea. Thyroid aspiration biopsy was first introduced in Korea in 1977. Currently, radiologists aspirate the thyroid nodule under the guidance of ultrasonography, and cytologic interpretation is only legally approved when a cytopathologist makes the diagnosis. In 2008, eight thyroid-related societies came together to form the Korean Thyroid Association. The Korean Society for Cytopathology and the endocrine pathology study group of the Korean Society for Pathologists have been updating the cytologic diagnostic guidelines. The Bethesda System for Reporting Thyroid Cytopathology was first introduced in 2009, and has been used by up to 94% of institutions by 2016. The average diagnosis rates are as follows for each category: I (12.4%), II (57.9%), III (10.4%), IV (2.9%), V (3.7%), and VI (12.7%). The malignancy rates in surgical cases are as follows for each category: I (28.7%), II (27.8%), III (50.6%), IV (52.3%), V (90.7%), and VI (100.0%). Liquid-based cytology has been used since 2010, and it was utilized by 68% of institutions in 2016. The categorization of thyroid lesions into “atypia of undetermined significance” or “follicular lesion of undetermined significance” is necessary to draw consensus in our society. Immunocytochemistry for galectin-3 and BRAF is used. Additionally, a molecular test for BRAF in thyroid FNACs is actively used. Core biopsies were performed in only 44% of institutions. Even the institutions that perform core biopsies only perform them for less than 3% of all FNACs. However, only 5% of institutions performed core biopsies up to three times more than FNAC.

Applying Ultrasound-Guided Core Needle Biopsy for Diagnosis of Thyroid Masses Preliminary Results From a Single Institution

The purpose of this study was to investigate the level of conclusive results obtained with ultrasound (US)‐guided core needle biopsy (CNB) and how this method should be applied for diagnosis of thyroid nodules.

Watch out for the WATCHMAN.

A 55-year-old man underwent percutaneous left atrial appendage (LAA) occlusion for recurrent bleeding during anticoagulation for atrial fibrillation. He had a history of myocardial infarction, ischaemic cardiomyopathy, hypertension, and …