Development of p21 activated kinase-targeted multikinase inhibitors that inhibit thyroid cancer cell migration

CONTEXT

The p21 activated kinases (PAKs) are a family of serine/threonine kinases that are downstream effectors of small GTPase Cdc42 and Rac. PAKs regulate cell motility, proliferation, and cytoskeletal rearrangement. PAK isoform expression and activity have been shown to be enhanced in cancer and to function as an oncogene in vivo. PAKs also have been implicated in cancer progression.

OBJECTIVE

In thyroid cancer, we have previously determined that PAK overactivation is common in the invasive fronts of aggressive tumors and that it is functionally involved in thyroid cancer cell motility using molecular inhibitors. We report the development of two new PAK-inhibiting compounds that were modified from the structure OSU-03012, a previously identified multikinase inhibitor that competitively blocks ATP binding of both phosphoinositide-dependent kinase 1 (PDK1) and PAK1.

RESULTS

Seventeen compounds were created by combinatorial chemistry predicted to inhibit PAK activity with reduced anti-PDK1 effect. Two lead compounds were identified based on the ability to inhibit PAK1 activity in an ATP-competitive manner without discernible in vivo PDK1 inhibitory activity in thyroid cancer cell lines. Both compounds reduced thyroid cancer cell viability. Although they are not PAK-specific on a multikinase screening assay, the antimigration activity effect of the compounds in thyroid cancer cells was rescued by overexpression of a constitutively active PAK1, suggesting this activity is involved in this biological effect.

CONCLUSIONS

We have developed 2 new multikinase inhibitors with anti-PAK activity that may serve as scaffolds for further compound development targeting this progression-related thyroid cancer target.

Approach to follow-up of the patient with differentiated thyroid cancer and positive anti-thyroglobulin antibodies

Anti-thyroglobulin antibodies are commonly identified in patients with differentiated follicular cell-derived thyroid cancer. When present, they interfere with the measurement of thyroglobulin (Tg), which is the primary biochemical marker used for disease surveillance, creating challenges in monitoring patients for residual or recurrent disease. Moreover, there is variability in measuring anti-Tg antibodies according to the different assays, such that not all patients with anti-Tg antibodies are identifiable on a single assay system. The persistence of anti-Tg antibodies, especially if levels are rising, may indicate persistent, recurrent, or progressive thyroid cancer. In contrast, declining anti-Tg antibody levels may indicate reduced tumor burden or the absence of disease. In this review, we will explore in a case-based manner the data supporting monitoring and treatment paradigms for patients with anti-Tg antibodies and will stress areas where more evidence is needed to better inform clinicians regarding the management of patients with this challenging situation.

SRGAP1 is a candidate gene for papillary thyroid carcinoma susceptibility

BACKGROUND

Papillary thyroid carcinoma (PTC) shows high heritability, yet efforts to find predisposing genes have been largely negative.

OBJECTIVES

The objective of this study was to identify susceptibility genes for PTC.

METHODS

A genome-wide linkage analysis was performed in 38 families. Targeted association study and screening were performed in 2 large cohorts of PTC patients and controls. Candidate DNA variants were tested in functional studies.

RESULTS

Linkage analysis and association studies identified the Slit-Robo Rho GTPase activating protein 1 gene (SRGAP1) in the linkage peak as a candidate gene. Two missense variants, Q149H and A275T, localized in the Fes/CIP4 homology domain segregated with the disease in 1 family each. One missense variant, R617C, located in the RhoGAP domain occurred in 1 family. Biochemical assays demonstrated that the ability to inactivate CDC42, a key function of SRGAP1, was severely impaired by the Q149H and R617C variants.

CONCLUSIONS

Our findings suggest that SRGAP1 is a candidate gene in PTC susceptibility. SRGAP1 is likely a low-penetrant gene, possibly of a modifier type.

In thyroidectomized patients with thyroid cancer, a serum thyrotropin of 30 μU/mL after thyroxine withdrawal is not always adequate for detecting an elevated stimulated serum thyroglobulin

BACKGROUND

The thyrotropin (TSH) level or duration of thyroid hormone withdrawal (THW) required to detect stimulated thyroglobulin (Tg) in differentiated thyroid cancer (DTC) monitoring is unknown. The objective of this study was to evaluate the TSH cutoff of >30 μU/mL as a means to detect stimulated Tg ≥2 ng/mL after THW (THW-Tg≥2), and sensitivity of the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) questionnaire for detecting hypothyroid symptoms.

METHODS

This was a prospective longitudinal cohort study done at a tertiary academic medical center. Forty-seven patients with DTC undergoing their first Tg stimulation or after previously abnormal Tg stimulation had weekly measurements of TSH and Tg during the 4 weeks THW, and repeated questionnaire assessments.

RESULTS

TSH did not reach a plateau in any patient, and in those whose Tg did not remain undetectable, Tg continued to rise. Seventy-five percent of patients had an undetectable Tg <0.2 ng/mL at baseline (95% were <0.5 mg/mL) with 16% remaining undetectable throughout THW. The majority of patients (72.7% and 97.8%) achieved TSH >30 μU/mL by 3 and 4 weeks THW, respectively. Of the 15 patients with maximum stimulated THW-Tg≥2, 38% were detected before the minimal TSH >30 μU/mL cutoff. At 2 weeks THW, 3 had a TSH>30 μU/mL, and none of them had Tg ≥2 ng/mL. At 3 weeks THW, 11 had a TSH >30 μU/mL, and 64% of them had Tg ≥2 ng/mL. Only 60% were detected at 3-week THW regardless of their TSH level. Eighty-six percent were detected by TSH 60-<80 μU/mL. Conversely, all patients whose serum Tg was <0.2 ng/mL when their serum TSH was >20 μU/mL did not achieve a THW-Tg≥2.

CONCLUSION

The minimal TSH cutoff of >30 μU/mL was inadequate to detect many patients with final stimulated THW-Tg≥2 during complete THW. TSH >80-100 μU/mL was a better cutoff, achieved in only 53% after 4-week THW. Conversely, we propose a preliminary THW-stopping rule for ending THW early in selected patients. In patients with a Tg <0.2 ng/mL when TSH >20 μU/mL, all had a final stimulated Tg ≤2 ng/mL, potentially saving qualifying patients 40% of THW duration compared to 4-week THW. FACIT-F correlated with TSH, but was not sensitive to detect mild hypothyroidism.

PTEN lipid phosphatase activity and proper subcellular localization are necessary and sufficient for down-regulating AKT phosphorylation in the nucleus in Cowden syndrome

CONTEXT

Germline mutations in PTEN are associated with phosphatase and tensin homolog deleted on chromosome 10 (PTEN) hamartoma tumor syndrome including Cowden syndrome (CS) and Cowden-like syndrome (CSL) that predisposes to high risks of benign and malignant tumors of thyroid and breast.

OBJECTIVE

The objective of the study was to analyze the subcellular pattern of phosphorylated (P)-AKT expression in nonmedullary thyroid cancers from PTEN hamartoma tumor syndrome patients and to investigate whether the lack of PTEN in the nucleus and/or lack of proper PTEN function in the nucleus affect(s) nuclear AKT activity in CS patients.

DESIGN

In all, 664 patients with CS/CSL were screened for PTEN germline mutations and nonmedullary thyroid cancers. Twenty-two patients who have both pathogenic PTEN germline mutations and nonmedullary thyroid cancers were selected. Thyroid samples from these patients were stained for PTEN and P-AKT. In our in vitro study, PTEN was knocked down or overexpressed in both thyroid cancer cells and breast cancer cells, and nuclear P-AKT was compared with the control.

RESULTS

Loss of PTEN protein was found in thyroid adenomas and carcinomas from all 22 (100%) PTEN(Mut+) CS/CSL patients. AKT activation was identified in 17 of 22 (77.3%) thyroid adenoma/carcinoma specimens, and most patients (63.7%) have activated nuclear AKT. Knockdown of PTEN in cells containing wild-type PTEN enhanced nuclear P-AKT, whereas expression of wild-type PTEN, but not phosphatase-dead mutants (C124S or G129E), markedly reduced nuclear P-AKT in PTEN null cells. We also showed that in breast cancer but not thyroid cancer cells, PTEN suppresses nuclear P-AKT mainly through decreasing P-AKT nuclear translocation by reducing the PIP3/P-AKT reservoir in the cytoplasm. In thyroid cancer cells, PTEN suppresses phosphorylation of AKT already resident in the nucleus.

CONCLUSIONS

PTEN is necessary and sufficient for inhibiting AKT activation in the nucleus through its intact lipid phosphatase activity and proper subcellular localization.

Modulation of sodium iodide symporter expression and function by LY294002, Akti-1/2 and Rapamycin in thyroid cells

The selective increase of Na(+)/I(-) symporter (NIS)-mediated active iodide uptake in thyroid cells allows the use of radioiodine I(131) for diagnosis and targeted treatment of thyroid cancers. However, NIS-mediated radioiodine accumulation is often reduced in thyroid cancers due to decreased NIS expression/function. As PI3K signaling is overactivated in many thyroid tumors, we investigated the effects of inhibitors for PI3K, Akt, or mTORC1 as well as their interplay on NIS modulation in thyroid cells under chronic TSH stimulation. PI3K inhibition by LY294002 increased NIS-mediated radioiodide uptake (RAIU) mainly through upregulation of NIS expression, however, mTORC1 inhibition by Rapamycin did not increase NIS-mediated RAIU despite increased NIS protein levels. In comparison, Akt inhibition by Akti-1/2 did not increase NIS protein levels, yet markedly increased NIS-mediated RAIU by decreasing iodide efflux rate and increasing iodide transport rate and iodide affinity of NIS. The effects of Akti-1/2 on NIS-mediated RAIU are not detected in nonthyroid cells, implying that Akti-1/2 or its derivatives may represent potential pharmacological reagents to selectively increase thyroidal radioiodine accumulation and therapeutic efficacy.

Sorafenib and Mek inhibition is synergistic in medullary thyroid carcinoma in vitro

Clinical trials using kinase inhibitors have demonstrated transient partial responses and disease control in patients with progressive medullary thyroid cancer (MTC). The goal of this study was to identify potential combinatorial strategies to improve on these results using sorafenib, a multikinase inhibitor with activity in MTC, as a base compound to explore signaling that might predict synergystic interactions. Two human MTC cell lines, TT and MZ-CRC-1, which harbor endogenous C634W or M918T RET mutations, respectively, were exposed to sorafenib, everolimus, and AZD6244 alone and in combination. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrasodium bromide (MTT) and poly (ADP-ribose) polymerase (PARP) cleavage assays were performed to measure cell survival and apoptosis. Western blots were performed to confirm activity of the compounds and to determine possible mechanisms of resistance and predictors of synergy. As a solitary agent, sorafenib was the most active compound on MTT assay. Western blots confirmed that sorafenib, everolimus, and AZD6244 inhibited their anticipated targets. At concentrations below its IC(50), sorafenib-treated TT and MZ-CRC-1 cells demonstrated transient inhibition and then re-activation of Erk over 6 h. In concordance, synergistic effects were only identified using sorafenib in combination with the Mek inhibitor AZD6244 (P<0.001 for each cell line). Cells treated with everolimus demonstrated activation of Akt and Ret via TORC2 complex-dependent and TORC2 complex-independent mechanisms respectively. Everolimus was neither additive nor syngergistic in combination with sorafenib or AZD6244. In conclusion, sorafenib combined with a Mek inhibitor demonstrated synergy in MTC cells in vitro. Mechanisms of resistance to everolimus in MTC cells likely involved TORC2-dependent and TORC2-independent pathways.

MicroRNA signature in thyroid fine needle aspiration cytology applied to "atypia of undetermined significance" cases

BACKGROUND

MicroRNA (miR) expression signatures are proposed to be able to differentiate thyroid cancer from benign thyroid lesions. We selected eight miRs (miR-146b, -221, -187, -197, -346, -30d, -138, and -302c) to examine the potential use of miRs to supplement diagnostic cytology in cases designated as "atypia of undetermined significance."

METHODS

miR expression was measured in thyroid fine needle aspiration (FNA) specimens by quantitative polymerase chain reaction. Gene expression analyses and linear discriminant analysis (LDA) were performed in a training sample set (n=60) to obtain a classification rule to predict FNA cases as benign or malignant. The predictions were cross-validated by comparing with the corresponding histological diagnoses. A validation sample set (n=68) was further tested with the established four-miR LDA classification rule.

RESULTS

A set of four miRs (miR-146b, -221, -187, and -30d) was identified that could differentiate malignant from benign lesions. A four-miR LDA classification rule was obtained and used to predict FNA cases as benign or malignant. For the training sample set, we obtained a diagnostic accuracy of 93.3%, sensitivity of 93.2%, specificity of 93.8%, positive predictive value (PPV) of 0.98, and negative predictive value (NPV) of 0.83. For the validation sample set, we obtained a diagnostic accuracy of 85.3%, sensitivity of 88.9%, specificity of 78.3%, PPV of 0.89, and NPV of 0.78. For the 30 atypia cases in the validation sample set, we obtained a diagnostic accuracy of 73.3%, sensitivity of 63.6%, specificity of 78.9%, PPV of 0.64, and NPV of 0.79. Based on the miR predictions, we classified the atypia cases predicted as "malignant" into "high risk" and those predicted as "benign" into "low risk" categories. While thyroid carcinomas, particularly papillary thyroid carcinomas (PTCs), were relatively enriched in the high-risk category, this particular miR panel is subject to inaccurate results in follicular neoplasias in atypia cases.

CONCLUSIONS

We demonstrate that miR amplification from FNA samples is feasible and that the particular four miR profile in this study can identify PTCs. However, further refinement is required for application to FNA cytology of "atypia of undetermined significance" cases due to low accuracy in classifying follicular neoplasias.

High-sensitivity TFA-free LC-MS for profiling histones

The analysis of proteins by RPLC commonly involves the use of TFA as an ion-pairing agent, even though it forms adducts and suppresses sensitivity. The presence of adducts can complicate protein molecular weight assignment especially when protein isoforms coelute as in the case of histones. To mitigate the complicating effects of TFA adducts in protein LC-MS, we have optimized TFA-free methods for protein separation. Protein standards and histones were used to evaluate TFA-free separations using capillary (0.3 mm id) and nanoscale (0.1 mm id) C(8) columns with the ion-pairing agents, formic acid or acetic acid. The optimized method was then used to examine the applicability of the approach for histone characterization in human cancer cell lines and primary tumor cells from chronic lymphocytic leukemia patients.

Telomere length and telomerase reverse transcriptase gene copy number in patients with papillary thyroid carcinoma

CONTEXT

The family risk ratio for papillary thyroid carcinoma (PTC) is among the highest of all cancers. Collectively, familial cases (fPTC) and sporadic cases (sPTC) are not known to show molecular differences. However, one study reported that telomeres were markedly shorter and the telomerase reverse transcriptase (TERT) gene was amplified and up-regulated in germline DNA from patients with fPTC compared with sPTC.

OBJECTIVE

The aim of this study was to evaluate telomere length and TERT gene amplification and expression in blood samples of fPTC and sPTC patients in a genetically distinct population from the previous study.

DESIGN

In 42 fPTC and 65 sPTC patients, quantitative real-time PCR was employed to measure the relative telomere length (RTL) and TERT gene copy number and RNA level. To validate the results using alternative methods, we further studied a subset of the original cohort consisting of randomly chosen fPTC (n = 10) and sPTC (n = 14) patients and controls (n = 21) by assessing both telomere length by flow fluorescent in situ hybridization and TERT gene expression by quantitative real-time PCR.

RESULTS

RTL and TERT gene copy number did not differ between fPTC and sPTC (P = 0.957 and P = 0.998, respectively). The mean RTL and TERT gene expression were not significantly different among the groups of the validation series (P = 0.169 and P = 0.718, respectively).

CONCLUSION

Our data show no difference between familial and sporadic PTC with respect to telomere length, TERT copy number, or expression in our cohort. Further investigations in additional cohorts of patients are desirable.

Germline SDHx variants modify breast and thyroid cancer risks in Cowden and Cowden-like syndrome via FAD/NAD-dependant destabilization of p53

Cowden syndrome (CS), a Mendelian autosomal-dominant disorder, predisposes to breast, thyroid and other cancers. Germline mutations in phosphatase and tensin homolog (PTEN) have been recently reported in 23% of a large series of classic CS. Here, we validated our small (n = 10) pilot study in a large patient series that germline variations in succinate dehydrogenase genes (SDHx) occur in 8% (49/608) of PTEN mutation-negative CS and CS-like (CSL) individuals (SDH^var+). None of these SDHx variants was found in 700 population controls (P < 0.0001). We then found that SDHx variants also occur in 6% (26/444) of PTEN mutation-positive (PTEN^mut+) CS/CSL individuals (PTEN^mut+/SDH^var+). Of 22 PTEN^mut+/SDH^var+ females, 17 had breast cancers compared with 34/105 PTEN^mut+ (P < 0.001) or 27/47 SDH^var+ patients (P = 0.06). Notably, individuals with SDH^var+ alone had the highest thyroid cancer prevalence (24/47) compared with PTEN^mut+ patients (27/105, P = 0.002) or PTEN^mut+/SDH^var+ carriers (6/22, P = 0.038). Patient-derived SDH^var+ lymphoblastoid cells had elevated cellular reactive oxygen species, highest in PTEN^mut+/SDH^var+ cells, correlating with apoptosis resistance. SDH^var+ cells showed stabilized and hyperactivated hypoxia inducible factor (HIF)1α signaling. Most interestingly, we also observed the loss of steady-state p53 in the majority of SDH^var+ cells. This loss of p53 was regulated by MDM2-independent NADH quinone oxidoreductase 1-mediated protein degradation, likely due to the imbalance of flavin adenine dinucleotide/nicotinamide adenine dinucleotide in SDH^var+ cells. Our data suggest the potential regulation of HIF1α, p53 and PTEN signaling by mitochondrial metabolism in CS/CSL tumorigenesis. Together, our findings suggest the importance of considering SDHx as candidate predisposing and modifier genes for CS/CSL-related malignancy risks, and a mechanism which suggests ways of therapeutic reversal or prevention.

Epigenetic deregulation of TCF21 inhibits metastasis suppressor KISS1 in metastatic melanoma

Metastatic melanoma is a fatal disease due to the lack of successful therapies and biomarkers for early detection and its incidence has been increasing. Genetic studies have defined recurrent chromosomal aberrations, suggesting the location of either tumor suppressor genes or oncogenes. Transcription factor 21 (TCF21) belongs to the class A of the basic helix-loop-helix family with reported functions in early lung and kidney development as well as tumor suppressor function in the malignancies of the lung and head and neck. In this study, we combined quantitative DNA methylation analysis in patient biopsies and in their derived cell lines to demonstrate that TCF21 expression is downregulated in metastatic melanoma by promoter hypermethylation and TCF21 promoter DNA methylation is correlated with decreased survival in metastatic skin melanoma patients. In addition, the chromosomal location of TCF21 on 6q23-q24 coincides with the location of a postulated metastasis suppressor in melanoma. Functionally, TCF21 binds the promoter of the melanoma metastasis-suppressing gene, KiSS1, and enhances its gene expression through interaction with E12, a TCF3 isoform and with TCF12. Loss of TCF21 expression results in loss of KISS1 expression through loss of direct interaction of TCF21 at the KISS1 promoter. Finally, overexpression of TCF21 inhibits motility of C8161 melanoma cells. These data suggest that epigenetic downregulation of TCF21 is functionally involved in melanoma progression and that it may serve as a biomarker for aggressive tumor behavior.

Multi-institutional phase II study of selumetinib in patients with metastatic biliary cancers

PURPOSE

Biliary cancers (BCs) carry a poor prognosis, but targeting the RAS/RAF/mitogen-activated protein kinase kinase (MEK)/extracellular signal-related kinase (ERK) pathway is of significance. Selumetinib is an inhibitor of MEK1/2, so this trial was designed to determine the safety and efficacy of selumetinib in BC.

PATIENTS AND METHODS

This was a multi-institutional phase II study of selumetinib at 100 mg given orally twice per day to patients with advanced BC. The primary end point was response rate. All patients were required to provide tissue before enrolling. The levels of phosphorylated ERK (pERK) and AKT (pAKT) were assessed by immunohistochemistry. Tumors were genotyped for the presence of BRAF- and/or RAS-activating mutations.

RESULTS

Twenty-eight eligible patients with a median age of 55.6 years were enrolled. Thirty-nine percent of patients had received one prior systemic therapy. Three patients (12%) had a confirmed objective response. Another 17 patients (68%) experienced stable disease (SD), 14 of whom (56%) experienced prolonged SD (> 16 weeks). Patients gained an average nonfluid weight of 8.6 pounds. Median progression-free survival was 3.7 months (95% CI, 3.5 to 4.9) and median overall survival was 9.8 months (95% CI, 5.97 to not available). Toxicities were mild, with rash (90%) and xerostomia (54%) being most frequent. Only one patient experienced grade 4 toxicity (fatigue). All patients had tissue available for analysis. No BRAF V600E mutations were found. Two patients with short-lived SD had KRAS mutations. Absence of pERK staining was associated with lack of response.

CONCLUSION

Selumetinib displays interesting activity and acceptable tolerability in patients with metastatic BC. Our results warrant further evaluation of selumetinib in patients with metastatic BC.

Frequency of germline PTEN mutations in differentiated thyroid cancer

BACKGROUND

Differentiated thyroid cancer (DTC) is seen in 3%-10% of individuals carrying a germline PTEN mutation. Patients with PTEN mutations are at risk for additional neoplasms as are their affected offspring. However, the frequency of PTEN mutations among DTC cases has not been systematically analyzed. The objective of this study was to determine the frequency of PTEN mutations in an unselected group of patients with DTC and to identify whether additional clinical features might indicate the need for referral for genetic counseling and possible testing.

METHODS

We collected personal medical and family history information, head circumference data, and blood from 259 consecutively identified clinic-based patients with DTC, unselected for personal or family history. Individuals were categorized for diagnostic criteria for Cowden syndrome (CS) using the 2009 National Comprehensive Cancer Network (NCCN) guidelines and underwent germline PTEN mutation analysis.

RESULTS

Two of the 259 patients (0.8%), with both follicular thyroid carcinoma and macrocephaly, were found to carry a germline mutation in the PTEN gene. The PTEN mutation frequency in unselected cases of follicular thyroid carcinoma was 4.8%.

CONCLUSION

The frequency of germline pathogenic PTEN mutations in an unselected series of patients with DTC is relatively low, but it is enriched by considering follicular histology and macrocephaly. These results suggest that by adding head circumference to the clinical assessment, thyroid cancer specialists can more effectively identify patients needing referral for cancer genetic services.

Metastatic dormancy and progression in thyroid cancer: targeting cells in the metastatic frontier

BACKGROUND

Metastatic dormancy, or the ability of cancer cells to survive but not progress in metastatic environments, is now recognized to be a common occurrence in cancer.

SUMMARY

From a clinical perspective, this phenomenon is common in metastatic well-differentiated thyroid cancer, whereby patients often present with distant metastases that remain stable for years after removal of the primary tumor and subsequent treatment. Experimental data suggest that metastases can develop throughout the life of a cancer and that progression in the distant environment depends on the biology of the cancer cells that metastasize as well as that of the various microenvironments they encounter. A firm understanding of how thyroid cancer cell progression is regulated in different metastatic environments is necessary to devise effective therapies targeting progressive metastatic thyroid cancer.

CONCLUSION

In this review, current models of metastatic progression and factors that regulate late-stage metastatic progression that are particularly relevant for thyroid cancer are discussed.

Multi-institutional phase II study of selumetinib in patients with metastatic biliary cancers

PURPOSE

Biliary cancers (BCs) carry a poor prognosis, but targeting the RAS/RAF/mitogen-activated protein kinase kinase (MEK)/extracellular signal-related kinase (ERK) pathway is of significance. Selumetinib is an inhibitor of MEK1/2, so this trial was designed to determine the safety and efficacy of selumetinib in BC.

PATIENTS AND METHODS

This was a multi-institutional phase II study of selumetinib at 100 mg given orally twice per day to patients with advanced BC. The primary end point was response rate. All patients were required to provide tissue before enrolling. The levels of phosphorylated ERK (pERK) and AKT (pAKT) were assessed by immunohistochemistry. Tumors were genotyped for the presence of BRAF- and/or RAS-activating mutations.

RESULTS

Twenty-eight eligible patients with a median age of 55.6 years were enrolled. Thirty-nine percent of patients had received one prior systemic therapy. Three patients (12%) had a confirmed objective response. Another 17 patients (68%) experienced stable disease (SD), 14 of whom (56%) experienced prolonged SD (> 16 weeks). Patients gained an average nonfluid weight of 8.6 pounds. Median progression-free survival was 3.7 months (95% CI, 3.5 to 4.9) and median overall survival was 9.8 months (95% CI, 5.97 to not available). Toxicities were mild, with rash (90%) and xerostomia (54%) being most frequent. Only one patient experienced grade 4 toxicity (fatigue). All patients had tissue available for analysis. No BRAF V600E mutations were found. Two patients with short-lived SD had KRAS mutations. Absence of pERK staining was associated with lack of response.

CONCLUSION

Selumetinib displays interesting activity and acceptable tolerability in patients with metastatic BC. Our results warrant further evaluation of selumetinib in patients with metastatic BC.

Group I p21-activated kinases regulate thyroid cancer cell migration and are overexpressed and activated in thyroid cancer invasion

p21-activated kinases (PAKs) are a family of serine/threonine kinases that regulate cytoskeletal dynamics and cell motility. PAKs are subdivided into group I (PAKs 1-3) and group II (PAKs 4-6) on the basis of structural and functional characteristics. Based on prior gene expression data that predicted enhanced PAK signaling in the invasive fronts of aggressive papillary thyroid cancers (PTCs), we hypothesized that PAKs functionally regulate thyroid cancer cell motility and are activated in PTC invasive fronts. We examined PAK isoform expression in six human thyroid cancer cell lines (BCPAP, KTC1, TPC1, FTC133, C643, and SW1746) by quantitative reverse transcription-PCR and western blot. All cell lines expressed PAKs 1-4 and PAK6 mRNA and PAKs 1-4 protein; PAK6 protein was variably expressed. Samples from normal and malignant thyroid tissues also expressed PAKs 1-4 and PAK6 mRNA; transfection with the group I (PAKs 1-3) PAK-specific p21 inhibitory domain molecular inhibitor reduced transwell filter migration by ∼50% without altering viability in all cell lines (P<0.05). BCPAP and FTC133 cells were transfected with PAK1, PAK2, or PAK3-specific small interfering RNA (siRNA); only PAK1 siRNA reduced migration significantly for both cell lines. Immunohistochemical analysis of seven invasive PTCs demonstrated an increase in PAK1 and pPAK immunoactivity in the invasive fronts versus the tumor center. In conclusion, PAK isoforms are expressed in human thyroid tissues and cell lines. PAK1 regulates thyroid cancer cell motility, and PAK1 and pPAK levels are increased in PTC invasive fronts. These data implicate PAKs as regulators of thyroid cancer invasion.

The relationship between body mass index and thyroid cancer pathology features and outcomes: a clinicopathological cohort study

BACKGROUND

Obesity has been implicated as a predisposing and disease-modifying factor in cancer. Epidemiological studies suggest that obesity is associated with an increased risk of thyroid cancer; however, the relationships between obesity and thyroid cancer stage or behavior are uncertain. We hypothesized that a higher body mass index (BMI) would be associated with aggressive thyroid cancer features and a higher incidence of persistent/recurrent disease.

METHODS

Two hundred fifty-nine consecutive patients with thyroid cancer were enrolled in this retrospective cohort study. Histopathological tumor features, stage at diagnosis, and disease status during and at the end of the study were determined based on chart review. BMI was calculated at the first clinical visit to our institution. The relationships between BMI and these parameters were assessed.

RESULTS

Mean follow-up time for the group was 6.2 yr (0.11-46 yr). No positive associations were identified between BMI and T, N, or M stage at diagnosis, vascular invasion, or recurrent or persistent disease on univariate or multivariate analyses. The absence of an association was also demonstrated on analysis by BMI quartiles. An unexpected inverse association was identified between BMI and nodal metastasis and tumor invasion on both univariate and multivariate analyses, suggesting that obesity may be associated with less aggressive tumor features, a finding that requires confirmatory studies.

CONCLUSION

Although obesity has been associated with increased thyroid cancer incidence, a higher BMI was found not to be associated with more aggressive tumor features or a greater likelihood of recurrence or persistence over the analyzed time period.

The PI3K-Akt-mTOR pathway in initiation and progression of thyroid tumors

The phosphoinositide-3 (OH) kinase (PI3K) signaling cascade is involved in regulating glucose uptake and metabolism, growth, motility, and other essential functions for cell survival. Unregulated activation of this pathway commonly occurs in cancer through a variety of mechanisms, including genetic mutations of kinases and regulatory proteins, epigenetic alterations that alter gene expression and translation, and posttranslational modifications. In thyroid cancer, constitutive activation of PI3K signaling has been shown to play a role in the genetic predisposition for thyroid neoplasia in Cowden's syndrome, and is recognized to be frequently overactivated in sporadic forms of thyroid cancer including those with aggressive clinical behaviors. In this review, the key signaling molecules in the PI3K signaling cascade, the abnormalities known to occur in thyroid cancer, and the potential for therapeutic targeting of PI3K pathway members will be discussed.

Phase II clinical trial of sorafenib in metastatic medullary thyroid cancer

PURPOSE

Mutations in the RET proto-oncogene and vascular endothelial growth factor receptor (VEGFR) activity are critical in the pathogenesis of medullary thyroid cancer (MTC). Sorafenib, a multikinase inhibitor targeting Ret and VEGFR, showed antitumor activity in preclinical studies of MTC.

PATIENTS AND METHODS

In this phase II trial of sorafenib in patients with advanced MTC, the primary end point was objective response. Secondary end points included toxicity assessment and response correlation with tumor markers, functional imaging, and RET mutations. Using a two-stage design, 16 or 25 patients were to be enrolled onto arms A (hereditary) and B (sporadic). Patients received sorafenib 400 mg orally twice daily.

RESULTS

Of 16 patients treated in arm B, one achieved partial response (PR; 6.3%; 95% CI, 0.2% to 30.2%), 14 had stable disease (SD; 87.5%; 95% CI, 61.7% to 99.5%), and one was nonevaluable. In a post hoc analysis of 10 arm B patients with progressive disease (PD) before study, one patient had PR of 21+ months, four patients had SD >or= 15 months, four patients had SD

CONCLUSION

Sorafenib is reasonably well tolerated, with suggestion of clinical benefit for patients with sporadic MTC. Caution should be taken because of the rare but fatal toxicity potentially associated with sorafenib.

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Key Words Collapse

MESH Headings

• Administration, Oral
• Adult
• Aged
• Benzenesulfonates/administration & dosage
• Benzenesulfonates/adverse effects
• Benzenesulfonates/therapeutic use
• Biomarkers, Tumor/metabolism
• Carcinoma, Medullary/drug therapy
• Carcinoma, Medullary/enzymology
• Carcinoma, Medullary/genetics
• Carcinoma, Medullary/mortality
• Carcinoma, Medullary/secondary
• Disease-Free Survival
• Female
• Humans
• Kaplan-Meier Estimate
• Magnetic Resonance Imaging
• Male
• Middle Aged
• Mutation
• Niacinamide/analogs & derivatives
• Phenylurea Compounds
• Positron-Emission Tomography
• Protein Kinase Inhibitors/administration & dosage
• Protein Kinase Inhibitors/adverse effects
• Protein Kinase Inhibitors/therapeutic use
• Proto-Oncogene Mas
• Proto-Oncogene Proteins c-ret/antagonists & inhibitors
• Proto-Oncogene Proteins c-ret/genetics
• Pyridines/administration & dosage
• Pyridines/adverse effects
• Pyridines/therapeutic use
• Receptors, Vascular Endothelial Growth Factor/antagonists & inhibitors
• Sorafenib
• Thyroid Neoplasms/drug therapy
• Thyroid Neoplasms/enzymology
• Thyroid Neoplasms/genetics
• Thyroid Neoplasms/mortality
• Thyroid Neoplasms/pathology
• Time Factors
• Tomography, X-Ray Computed
• Treatment Outcome
• United States
• Young Adult

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Grants

• N01CM62207 NCI NIH HHS
• N01-CM-62207 NCI NIH HHS

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Long-term efficacy of lymph node reoperation for persistent papillary thyroid cancer

OBJECTIVE

The objective of the study was to determine the outcome of surgical resection of metastatic papillary thyroid cancer (PTC) in cervical lymph nodes after failure of initial surgery and I(131) therapy.

DESIGN

This was a retrospective clinical study.

SETTING

The study was conducted at a university-based tertiary cancer hospital.

PATIENTS

A cohort of 95 consecutive patients with recurrent/persistent PTC in the neck underwent initial reoperation during 1999-2005. All had previous thyroidectomy (+/-nodal dissection) and I(131) therapy. Twenty-five patients with antithyroglobulin (Tg) antibodies were subsequently excluded.

MAIN OUTCOME MEASURES

Biochemical complete remission (BCR) was stringently defined as undetectable TSH-stimulated serum Tg.

RESULTS

A total of 107 lymphadenectomies were undertaken in these 70 patients through January 2010. BCR was initially achieved in 12 patients (17%). Of the 58 patients with detectable postoperative Tg, 28 had a second reoperation and BCR was achieved in five (18%), seven had a third reoperation, and none achieved BCR. No patient achieving BCR had a subsequent recurrence after a mean follow-up of 60 months (range 4-116 months). In addition, two more patients achieved BCR during long-term follow-up without further intervention. In total, 19 patients (27%) achieved BCR and 32 patients (46%) achieved a TSH-stimulated Tg less than 2.0 ng/ml. Patients who did not achieve BCR had significant reduction in Tg after the first (P < 0.001) and second (P = 0.008) operations. No patient developed detectable distant metastases or died from PTC.

CONCLUSIONS

Surgical resection of persistent PTC in cervical lymph nodes achieves BCR, when most stringently defined, in 27% of patients, sometimes requiring several surgeries. No biochemical or clinical recurrences occurred during follow-up. In patients who do not achieve BCR, Tg levels were significantly reduced. The long-term durability and impact of this intervention will require further investigation.