Joanna Klubo-Gwiezdzinska

Efficacy of dosimetric versus empiric prescribed activity of 131I for therapy of differentiated thyroid cancer.

Abstract Background: The optimal management of high-risk patients with differentiated thyroid cancer (DTC) consists of thyroidectomy followed by radioiodine (131I) therapy. The prescribed activity of 131I can be determined using two approaches: 1) empiric prescribed activity of 131I (E-Rx); and 2) dosimetry-based prescribed activity of 131I (D-Rx). Aim: The aim of the study was to compare the relative treatment efficacy and side effects of D-Rx vs. E-Rx. Methods: A retrospective analysis was performed of patients with distant metastases and/or locoregionally advanced radioiodine-avid DTC who were treated with either D-Rx or E-Rx. Response to treatment was based on RECIST (Response Evaluation Criteria in Solid Tumors) 1.1 criteria. Results: The study group consisted of 87 patients followed for 51 ± 35 months, of whom 43 were treated with D-Rx and 44 with E-Rx. Multivariate analysis, controlling for age, gender, and status of metastases revealed that the D-Rx group tended to be 70% less likely to progress (odds ratio, 0.29; 95% confidence interval, 0.087–1.02; P = 0.052) and more likely to obtain complete response (CR) compared to the E-Rx group (odds ratio, 8.2; 95% confidence interval, 1.2–53.5; P = 0.029). There was an association in the D-Rx group between the observed CR and percentage of maximum tolerable activity given as a first treatment of 131I (P = 0.030). The advantage of D-Rx was specifically apparent in the locoregionally advanced group because CR was significantly higher in D-Rx vs. E-Rx in this group of patients (35.7 vs. 3.3%; P = 0.009). The rates of partial response, stable disease, and progression-free survival, as well as the frequency of side effects, were not significantly different between the two groups. Conclusion: Higher efficacy of D-Rx with a similar safety profile compared to E-Rx supports the rationale for employing individually prescribed activity in high-risk patients with DTC.

Radioiodine Treatment of Metastatic Thyroid Cancer: Relative Efficacy and Side Effect Profile of Preparation by Thyroid Hormone Withdrawal Versus Recombinant Human Thyrotropin

BACKGROUND To effectively treat differentiated thyroid cancer (DTC) with radioiodine (RAI) it is necessary to raise serum thyrotropin (TSH) levels either endogenously by thyroid hormone withdrawal (THW) or exogenously by administration of recombinant human TSH (rhTSH). The aim of our study was to compare the relative efficacy and side effect profile of rhTSH versus THW preparation for RAI therapy of metastatic DTC. METHODS Fifty-six patients (31 women and 25 men) with RAI-avid distant metastases of DTC treated with either rhTSH-aided (n=15) or THW-aided RAI (n=41) and followed for 72±36.2 months were retrospectively analyzed. The groups were comparable in regard to mean size of target lesions (rhTSH vs. THW 6.4 vs. 4.8 cm, p=0.41), mean baseline thyroglobulin level (6995 vs. 5544 ng/mL, p=0.83), distribution of micronodular and macronodular pulmonary metastases (67% vs. 63%, p=0.54, 13% vs. 15% p=0.64, respectively), osseous (53% vs. 29%, p=0.09), brain (0% vs. 2%, p=0.73), and liver/kidney metastases (13% vs. 2%, p=0.61). Patients in the rhTSH group were older (rhTSH vs. THW mean 62 vs. 49 years, p=0.01), and received lower cumulative RAI dose (256 vs. 416 mCi, p=0.03), which was more frequently based on dosimetric calculations (80% vs. 46%, p=0.024). Responses to treatment were based on RECIST 1.1 criteria. RESULTS Adjusted by age rates of complete response (CR), stable disease (SD), progressive disease (PD), and progression free survival (PFS) were not different between the groups (rhTSH vs. THW CR hazard ratio [HR] 0.97, 95% CI 0.08-11.42, p=0.982; SD HR 3.22, 95% CI 0.79-13.18, p=0.104, PD HR 0.26, 95% CI 0.52-1.26, p=0.094; PFS HR 0.41, 95% CI 0.14-1.23, p=0.112). The only independent risk factor for nonresponding to treatment and presentation with PD was age (HR 1.06, 95% CI 1.02-1.11, p=0.008). Age was also an independent factor affecting PFS (HR 1.04 for each year, 95% CI 1.02-1.07, p=0.001). Rates of leukopenia, thrombocytopenia, xerostomia, and restrictive pulmonary disease after RAI were not significantly different (rhTSH vs. THW 30% vs. 28%, p=0.61, 10% vs. 0%, p=0.37, 0% vs. 12%, p=0.20, 0% vs. 2%, p=0.73, respectively). CONCLUSIONS Patients with metastatic DTC prepared with rhTSH achieve comparable benefit of RAI therapy as those treated after THW.

Does an undetectable rhTSH-stimulated Tg level 12 months after initial treatment of thyroid cancer indicate remission?

Objectives  Routine monitoring after the initial treatment of differentiated thyroid cancer (DTC) includes periodic cervical ultrasonography (US) and measurement of serum thyroglobulin (Tg) during thyrotrophin (TSH) suppression and after recombinant human TSH (rhTSH) stimulation. The aim of our study was to evaluate the utility of repeated rhTSH‐stimulated Tg measurements in patients with DTC who have had no evidence of disease at their initial rhTSH stimulation test performed 1 year after the treatment.

Salivary gland malignancy and radioiodine therapy for thyroid cancer.

BACKGROUND The risk of second primary malignancies in patients with well-differentiated thyroid cancer is of special interest because of the common use of radioactive iodine (RAI) ablation and/or treatment of these patients and the theoretical risk of subsequent nonthyroid malignancies associated with the radiation exposure. This brief report focuses specifically on the occurrence of second primary malignancies of the salivary glands. RAI residency within salivary tissues is known to have both acute and chronic consequences on salivary function, but secondary neoplasia is quite unusual. SUMMARY We present a very rare case of a patient with papillary thyroid cancer treated with 600 mCi of RAI, who subsequently developed salivary gland cancer. CONCLUSIONS We recommend salivary gland protection to diminish potential side effects after the exposure to radioiodine. On the basis of our experience we suggest administration of sialogogues (such as lemon juice) continuously, every 30-60 minutes for 24 hours, after RAI administration.

The HIV Protease Inhibitor Nelfinavir Down-Regulates RET Signaling and Induces Apoptosis in Medullary Thyroid Cancer Cells

CONTEXT Mutations of RET tyrosine kinase are associated with the development of medullary thyroid cancer (MTC). The heat shock protein (HSP) 90 chaperone is required for folding and stability of RET mutants. HSP90 is a molecular target for the HIV protease inhibitor nelfinavir (NFV). OBJECTIVE We hypothesized that treatment with NFV may lead to the inhibition of RET signaling and induction of apoptosis in MTC cells. DESIGN Two human MTC cell lines, TT and MZ-CRC-1, which harbor endogenous C634W or M918T RET mutations, respectively, were exposed to clinically achievable concentrations of NFV. JC-1 staining and caspase-3 cleavage assays were performed to measure mitochondrial membrane potential and apoptosis. Activation of RET signaling was examined by Western blot. Autophagy was monitored by the detection of the light-chain 3BII. Expression of HSP90 and LC3B were examined in 36 human MTCs. RESULTS At a therapeutic serum concentration (10 μM), NFV inhibited the viability of TT and MZ-CRC-1 cells by 55% and 10%, respectively. In a dose-dependent manner, NFV inhibited cyclin D1 and caused caspase-3 cleavage. NFV decreased the level of RET protein and blocked the activation of RET downstream targets (phosphorylated ERK, phosphorylated AKT, and p70S6K/pS6). NFV induced metabolic stress, activated AMP-activated protein kinase and increased autophagic flux. Pharmacological inhibition of autophagy (chloroquine) augmented NFV-inducible cytotoxicity, suggesting that autophagy was protective in NFV-treated cells. NFV led to mitochondrial membrane depolarization and induced both oxidative stress and DNA damage. An antioxidant (n-acetylcysteine) attenuated DNA damage and prevented NFV-inducible apoptosis. HSP90 overexpression was found in 17 of 36 human MTCs and correlated with metastases and RET mutations. LC3B was detected in 20 of 36 human MTCs. CONCLUSIONS NFV has a wide spectrum of activity against MTC cells, and its cytotoxicity can be augmented by inhibiting autophagy. Expression of NFV molecular targets in metastatic MTC suggests that NFV has a potential to become a thyroid cancer therapeutic agent.

Levothyroxine Treatment in Pregnancy: Indications, Efficacy, and Therapeutic Regimen

The prevalence of overt and subclinical hypothyroidism during pregnancy is estimated to be 0.3–0.5% and 2–3%, respectively. Thyroid autoantibodies are found in 5–18% of women in the childbearing age. The aim of this review is to underscore the clinical significance of these findings on the health of both the mother and her offspring. Methods of evaluation of thyroid function tests (TFTs) during pregnancy are described as are the threshold values for the diagnosis of overt and subclinical hypothyroidism or hypothyroxinemia. Anticipated differences in TFTs in iodine-sufficient and iodine-deficient areas are discussed and data are provided on potential complications of hypothyroidism/hypothyroxinemia and autoimmune thyroid disease during pregnancy and adverse effects for the offspring. The beneficial effects of levothyroxine therapy on pregnancy outcomes and offspring development are discussed with a proposed treatment regimen and follow up strategy.

Glucose-deprivation increases thyroid cancer cells sensitivity to metformin

Metformin inhibits thyroid cancer cell growth. We sought to determine if variable glucose concentrations in medium alter the anti-cancer efficacy of metformin. Thyroid cancer cells (FTC133 and BCPAP) were cultured in high-glucose (20 mM) and low-glucose (5 mM) medium before treatment with metformin. Cell viability and apoptosis assays were performed. Expression of glycolytic genes was examined by real-time PCR, western blot, and immunostaining. Metformin inhibited cellular proliferation in high-glucose medium and induced cell death in low-glucose medium. In low-, but not in high-glucose medium, metformin induced endoplasmic reticulum stress, autophagy, and oncosis. At micromolar concentrations, metformin induced phosphorylation of AMP-activated protein kinase and blocked p-pS6 in low-glucose medium. Metformin increased the rate of glucose consumption from the medium and prompted medium acidification. Medium supplementation with glucose reversed metformin-inducible morphological changes. Treatment with an inhibitor of glycolysis (2-deoxy-d-glucose (2-DG)) increased thyroid cancer cell sensitivity to metformin. The combination of 2-DG with metformin led to cell death. Thyroid cancer cell lines were characterized by over-expression of glycolytic genes, and metformin decreased the protein level of pyruvate kinase muscle 2 (PKM2). PKM2 expression was detected in recurrent thyroid cancer tissue samples. In conclusion, we have demonstrated that the glucose concentration in the cellular milieu is a factor modulating metformins anti-cancer activity. These data suggest that the combination of metformin with inhibitors of glycolysis could represent a new strategy for the treatment of thyroid cancer.

BRAF(V600E) mutation analysis from May-Grünwald Giemsa-stained cytological samples as an adjunct in identification of high-risk papillary thyroid carcinoma.

The BRAFV600E mutation is specific for thyroid papillary cancer (PTC) and correlates with PTCs invasiveness. This study investigated whether detection of BRAFV600E mutation can be performed on routinely stained FNABs. We also examined if establishment of the BRAFV600E mutation could help in identification of patients at higher risk for metastatic disease. DNA was isolated from 134 FNABs samples (20 follicular neoplasm, ten suspicious for malignancy, and 104 malignant) using Pinpoint Slide DNA Isolation System. BRAFV600E mutation was detected by PCR followed by sequencing. DNA was successfully extracted from all examined FNABs samples. In follicular neoplasm, suspicious for malignancy and malignant FNABs, BRAFV600E mutation was found in 0/20 (0%), 2/10 (20%), and 47/104 (45.2%) of cases, respectively. Extra-thyroidal extension was detected in 35/47 (74.4%) BRAFV600E positive and in 24/57 (42.1%) wild-type BRAF cases (p = 0.001). Metastases were detected in 37/47 (78.7%) BRAFV600E positive and in 28/57 (49.1%) wild-type BRAF cases (p = 0.002). Our results showed that stained FNAB specimens can be used for DNA extraction and assessment of BRAFV600E mutation. Detection of BRAFV600E mutation had limited value in diagnoses of malignancy in follicular neoplasms but can ascertain malignancy in subset of suspicious for malignancy FNABs. In malignant FNABs, BRAFV600E mutation was significantly associated with presence of extra-thyroidal extension and metastases after surgery.

Inhibition of gap junction transfer sensitizes thyroid cancer cells to anoikis

Resistance to anoikis (matrix deprivation-induced apoptosis) is a critical component of the metastatic cascade. Molecular mechanisms underlying resistance to anoikis have not been reported in thyroid cancer cells. For an in vitro model of anoikis, we cultured follicular, papillary, and anaplastic thyroid cancer cell lines on poly-HEMA-treated low-adherent plates. We also performed immunohistochemical analysis of human cancer cells that had infiltrated blood and/or lymphatic vessels. Matrix deprivation was associated with establishment of contacts between floating thyroid cancer cells and formation of multi-cellular spheroids. This process was associated with activation of gap junctional transfer. Increased expression of the gap junction molecule Connexin43 was found in papillary and anaplastic cancer cells forming spheroids. All non-adherent cancer cells showed a lower proliferation rate compared with adherent cells but were more resistant to serum deprivation. AKT was constitutively activated in cancer cells forming spheroids. Inhibition of gap junctional transfer through Connexin43 silencing, or by treatment with the gap junction disruptor carbenoxolone, resulted in loss of pAKT and induction of apoptosis in a cell-type-specific manner. In human thyroid tissue, cancer cells that had infiltrated blood vessels showed morphological similarity to cancer cells forming spheroids in vitro. Intra-vascular cancer cells demonstrated prominent AKT activation in papillary and follicular cancers. Increased Connexin43 immunoreactivity was observed only in intra-vascular papillary cancer cells. Our data demonstrate that establishment of inter-cellular communication contributes to thyroid cancer cell resistance to anoikis. These findings suggest that disruption of gap junctional transfer could represent a potential therapeutic strategy for prevention of metastases.

The expression of translocator protein in human thyroid cancer and its role in the response of thyroid cancer cells to oxidative stress

The translocator protein (TSPO), formerly known as a peripheral benzodiazepine receptor, exerts pro-apoptotic function via regulation of mitochondrial membrane potential. We examined TSPO expression in human thyroid tumors (25 follicular adenomas (FA), 15 follicular cancers (FC), and 70 papillary cancers (PC)). The role of TSPO in the regulation of cell growth, migration, and apoptosis was examined in thyroid cancer cell lines after TSPO knockdown with siRNA and after treatment with TSPO antagonist (PK11195). Compared with normal thyroid, the level of TSPO expression was increased in FA, FC, and PC in 24, 26.6, and 55.7% of cases respectively. Thyroid cancer cell lines demonstrated variable levels of TSPO expression, without specific association with thyroid oncogene mutations. Treatment with inhibitors of PI3K/AKT or MEK/ERK signaling was not associated with changes in TSPO expression. Treatment with histone deacetylase inhibitor (valproic acid) increased TSPO expression in TSPO-deficient cell lines (FTC236 cells). TSPO gene silencing or treatment with PK11195 did not affect thyroid cancer cell growth and migration but prevented depolarization of mitochondrial membranes induced by oxidative stress. Induction of TSPO expression by valproic acid was associated with increased sensitivity of FTC236 to oxidative stress-inducible apoptosis. Overall, we showed that TSPO expression is frequently increased in PC. In vitro data suggested the role of epigenetic mechanism(s) in the regulation of TSPO in thyroid cells. Implication of TSPO in the thyroid cancer cell response to oxidative stress suggested its potential role in the regulation of thyroid cancer cell response to treatment with radioiodine and warrants further investigation.