Journal of Surgical Oncology

REVIEW Molecular Markers for Thyroid Cancer Diagnosis, Prognosis, and Targeted Therapy LINWAH YIP, MD* Division of Endocrine Surgery and Surgical Oncology, Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania

Molecular markers including gene expression profiles, somatic gene alterations, and circulating peripheral markers have augmented diagnostic, prognostic, and therapeutic options for thyroid cancer patients.

J. Surg. Oncol. ß 2014 Wiley Periodicals, Inc.

KEY WORDS: thyroid; thyroid cancer; thyroid nodule; molecular targeted therapy

Thyroid cancer is one of the few cancers that is rising in incidence and is most commonly diagnosed following ultrasound and ultrasound‐ guided fine needle aspiration biopsy (FNAB) of a thyroid nodule [1]. The rising rates appear to be coincident with the widespread use of ultrasound and FNAB [2]. However, early detection may not be the only reason for the increased incidence as the trend is also observed in men as well as in women, among all ages, in all tumor sizes, and across different racial and ethnic groups [3–5]. Despite the increase in incidence, the mortality rate for thyroid cancer patients has overall remained 240,000 gene and exon transcripts were screened in 178 thyroid samples. The variable expression of 167 genes was then identified as most likely to be associated with histologically benign nodules. Only 24 indeterminate FNAB samples were included in the initial validation cohort and an observed sensitivity of 100% and specificity of 73% was reported [15]. The performance of the commercially‐available gene‐expression classifier (GEC) was then further analyzed in a study of 265 nodules with indeterminate FNAB results and histology [16]. The cohort rate of histologic malignancy was 32%, and the panel had a specificity of 52%, positive predictive value (PPV) 47%, sensitivity 92%, and negative predictive value (NPV) 93%.

Dr. Yip receives University of Pittsburgh Medical Center and NIH/NIA grant support for study of molecular markers. *Correspondence to: Linwah Yip, MD, University of Pittsburgh School of Medicine, Suite 101 ‐ 3471 Fifth Avenue Pittsburgh, PA 15213, USA. Fax: þ412‐648‐9551. E‐mail: [email protected] Received 14 May 2014; Accepted 14 July 2014 DOI 10.1002/jso.23768 Published online in Wiley Online Library (wileyonlinelibrary.com).

2

Yip

The GEC panel missed 7/85 (8%) malignancies; four were papillary (size range 0.6–1.2 cm), two were follicular variant papillary thyroid cancer (FVPTC) (size range 1–3 cm), and most concerning, one was a 3.5 cm oncocytic carcinoma [16]. The NPV in nodules with AUS/FLUS and FN cytology results was 95% and 94%, respectively. Thus, the GEC panel did decrease but did not completely eliminate the cancer risk. Furthermore, the malignancy risk with GEC‐benign results was not equivalent to a FNAB with benign cytology which was 3.7% in the previously discussed meta‐analysis [8]. GEC cannot reliably be used for nodules with suspicious cytology results as the NPV of 85% was not high enough to exclude the possibility of cancer. Another limitation is that the overall high false positive rate of 53% prevented use of GEC results to indicate the possible need for initial total thyroidectomy [16]. The cytology specimen for the GEC test is typically collected by the ordering clinician and classified into one of the six Bethesda categories by a selected commercial cytopathology group. Only a limited number of academic centers are allowed to use in‐house cytopathologists that are not part of the selected commercial group. The GEC assay is then performed only on cytology results that are either AUS/FLUS or FN, and reported as either GEC‐benign or GEC‐suspicious. Two recent reports that independently evaluated GEC use in single center studies underscored the influence of cancer prevalence on interpretation of NPV and PPV [17,18]. Harrell et al. evaluated 35 patients with indeterminate cytology, histology, and GEC results, and observed a high cancer rate of 51%. Although the calculated sensitivity was 94% and similar to the previously published sensitivity rate, the high malignancy rate in their series resulted in a lower than expected NPV of 80% [18]. McIver et al. utilized in‐house cytology and pathology for interpretation of their specimens, and 36 FNAB specimens had indeterminate cytology, histology, and GEC results for further analysis. The cancer incidence was quite low at 17%, and test sensitivity and specificity were 83% and 10%, respectfully. Because of the lower pre‐test probability of malignancy and diminished sensitivities and specificities, decreases in NPV (75%) and PPV (16%) were observed [17]. The clinical application of the gene expression classifier has been limited to diagnostic use only although other genome‐wide expression analyses have identified patterns that are associated with disease outcomes. Nilubol et al. analyzed gene expression array data from 64 PTC patients and identified six genes (CPSF2, LARS, AURKC, TFDP1, TRNT1, and BCL11A) with differential expression that was significantly associated with mortality [19]. In yet another analysis of gene expression data, MUC1 amplification using real‐time quantitative PCR was associated with aggressive papillary thyroid cancers (PTC) and its over expression was confirmed in an independent validation set of PTC to be associated with decreased recurrence‐free survival [20]. However confirmatory studies to verify the prognostic significance of these initial findings still need to be performed and prospectively validated.

GENETIC MUTATIONS AND REARRANGEMENTS Gene mutations and rearrangements commonly associated with thyroid cancer can be detected in both FNAB and histology specimens. The most frequently tested gene alterations affect the MAPK and PI3K‐ AKT pathways which have been implicated in thyroid carcinogenesis. Activating mutations in both of these pathways have been shown to lead to upregulation of genes that regulate cellular proliferation, differentiation, and survival [21]. Mutations may often also correspond to histologic subtype providing additional preoperative risk stratification [21–23]. For example, follicular thyroid cancers (FTC) are more likely to have mutations in the RAS and PTEN genes while BRAF V600E and RET/PTC rearrangements are more common in conventional PTC (Table I). Interestingly, FVPTC which has morphologic features that is Journal of Surgical Oncology

TABLE I. Common Gene Alterations in Thyroid Cancer Genetic alteration Mutations BRAF V600E

BRAF K601E RAS

PTEN

P53 PIK3CA

Rearrangements RET/PTC PAX8‐PPARg

Associated thyroid tumors

Conventional PTC Tall Cell Variant PTC PDTC Anaplastic Follicular Variant PTC Follicular Adenoma Conventional PTC Follicular Variant PTC FTC HCC PDTC Anaplastic Sporadic MTC FTC HCC Conventional PTC (rare) Anaplastic Conventional PTC HCC Anaplastic FTC PDTC Anaplastic Conventional PTC Follicular Variant PTC (rare) Follicular Variant PTC FTC

FTC, follicular thyroid cancer; HCC, Hurthle cell carcinoma; PDTC, poorly‐ differentiated thyroid cancer; PTC, papillary thyroid cancer.

usually consistent with PTC but biologic behavior that may be more similar to FTC, shares gene alterations with both histologic types. BRAF V600E is the most common gene alteration in thyroid cancer, and is associated with up to 40–50% of conventional PTC. When identified in preoperative biopsy specimens, BRAF V600E has greater than 99% PPV for PTC. The mutation may also be associated with aggressive histologic PTC features including tall‐cell variant subtype, extrathyroidal extension, lymph node metastasis, recurrence, as well as disease‐specific mortality [23,24]. The additional prognostic information gained from preoperative BRAF V600E testing may help direct surgical management such as whether to perform prophylactic central compartment lymph node dissection but this is controversial [25]. BRAF K601E is the 2nd most common BRAF mutation detected in thyroid cancer. In a study evaluating characteristics of 120 BRAF‐ positive indeterminate FNAB results, BRAF K601E was detected in 50% of the results categorized as either AUS/FLUS or FN, and the majority were FVPTC on histology [26]. RAS has a key role in signal transduction from tyrosine kinase and G protein‐coupled receptors to effectors of both the MAPK and PI3K‐AKT pathways. Point mutations cause increased affinity of RAS to GTP or inhibit the autocatalytic GTP‐ase function, and both cause constitutive activation of downstream pathways [27]. In indeterminate FNAB specimens, RAS mutations are the most common gene alterations identified and can include point mutations in the N‐, K‐, and H‐RAS hotspots in codons 12/13 and 61 [28]. All three mutant isoforms have been identified in up to 48% of benign follicular adenomas, 50–60% of FTC, and less frequently (20%) in PTC [27]. In one recent study that included 63 FNAB specimens, the preoperative detection of RAS in FNAB cytology was associated with an 80–85% risk of malignancy and most frequently was histologic FVPTC (90%) [29]. Bilateral multifocal disease was diagnosed in 50% and lymph node metastasis was rare. Most

Molecular Markers in Thyroid Cancer RAS‐associated thyroid cancers are indolent, however, RAS mutations have also been identified in medullary thyroid cancer, poorly differentiated, and anaplastic thyroid cancers. RET rearrangements in PTC have been well documented and more than 10 different types of translocations have been described that are identified in 10–20% of PTC [30,31]. Typically the 30 tyrosine kinase portion of the RET gene fuses with the 50 of a different gene resulting in ligand‐ independent dimerization and constitutive activation of effector genes in both the MAPK and PI3‐AKT pathways. The two most common fusion proteins are RET/PTC1 and RET/PTC3 which are paracentric versions with the 50 domain of two genes on chromosome 10: CCDC6 and NCOA4, respectively [30]. A higher incidence of RET/PTC rearrangements is seen in PTC patients with a previous history of radiation exposure (50–80%) and in younger patients (40–70%) [32–34]. RET/PTC1 positive tumors demonstrate either classic papillary architecture or diffuse sclerosing features, while RET/PTC3 is associated with solid variant PTC. All of the RET/PTC tumor subtypes have a higher rate of lymph node metastases [35]. In an evaluation of temporal changes in molecular profiles of thyroid cancers, the proportion of RET/PTC‐positive PTC decreased over time suggesting that exposure to ionizing radiation has a diminishing contribution to thyroid carcinogenesis [36]. A gene rearrangement leading to the fusion of the thyroid‐specific paired domain transcription factor, PAX8, and the peroxisome proliferator‐ activated receptor gene, PPARg, which plays an important role in lipid metabolism, was discovered in FTC in 2000 [37]. The PAX8/PPARg rearrangement results in overexpression of the fusion protein, but the carcinogenic mechanism of action is still unclear. PAX8 plays an essential role in thyrocyte development, as well as in the gene expression of the sodium‐iodide symporter, thyroglobulin, and the TSH receptor [38]. The fusion protein antagonizes the action of PPARg via a dominant‐negative inhibition that has been shown to be a potential causative agent in FTC tumorigenesis [39]. PAX8/PPARg translocation is found in 30–40% of classic FTC, 2–10% of FA, and in FVPTC [40,41]. Similar to RAS‐positive FAs, PAX8/PPARg‐positive FA may actually represent carcinomas in‐situ. PAX8/PPARg‐positive FTCs tend to occur in younger patients with tumor characteristics that have solid patterns and vascular invasion [40].

3

1 and 3 rearrangements) with cytologic and histologic correlation. The cancer rate was 24%, and unusual false positive mutation testing results occurred in 11% [28]. RAS positivity was the primary source of false positive testing results. When BRAF, RET/PTC1, 3, or PAX8‐PPARG was detected preoperatively, the risk of malignancy was 100% regardless of cytology category. For all indeterminate FNAB results, the MT panel had specificity 98%, PPV 89%, sensitivity 61%, and NPV 89% [28]. The high PPV and specificity allowed appropriate stratification of otherwise indeterminate FNAB results into those that carry a high risk of cancer, and can be used to direct appropriate extent of initial thyroidectomy and/or lymphadenectomy. The high diagnostic specificity of the MT panel was recently verified in an industry‐sponsored multi‐institutional non‐interventional study using in‐house pathologists who were blinded to MT panel results [44]. A total of 53 patients had indeterminate FNAB results, MT panel, and histology. The malignancy rate was 47% and test sensitivity, specificity were 44% and 89%, respectively. The most commonly missed malignancy was FVPTC (Table II). The cost outcomes of adding prospective mutation testing has been further modeled in hypothetical decision tree analysis which showed that added costs of preoperative mutation testing were offset by reductions in the number of necessary 2‐stage thyroidectomies [45]. Furthermore, in study of patient outcomes after incorporation of an institutional algorithm for prospective mutation testing, when preoperative mutation testing was routinely performed for FNAB results classified as AUS/FLUS or FN, a 2.5‐fold reduction in 2‐stage thyroidectomy for clinically significant thyroid cancer (P < 0.001) was observed [46]. Although the risk of malignancy is lower with mutation panel negative FNAB results, the risk is not low enough to reliably exclude the possibility of malignancy. Indeterminate cytology biopsy results with negative mutation testing are still associated with a 14% risk of cancer, and this rate varies by cytology category. New techniques, such as next generation sequencing technology, may allow for cost‐effective and sensitive screening of multiple gene alterations, and has already been investigated for mutations that are thyroid‐specific. Accurate testing is observed using either paraffin embedded or FNAB samples with acceptable concordance to conventional Sanger sequencing methods [47]. Using the Ion Torrent platform and an expanded 12 gene panel that is inclusive of 284 mutational hotspots, Nikiforova et al. were able to detect mutations in genes such as TSHR, PIK3CA, and p53 [48]. Two of twenty seven conventional PTC had coexistent BRAF V600E with p53 and/or PIK3CA mutations which are typically more characteristic of aggressive thyroid cancers. The identification of more than one driver mutation may provide preoperative prognostic information that may beneficially guide surgical management [23,48,49].

Diagnostic Utility Because of the number of gene alterations involved in thyroid carcinogenesis, adjunct testing for a panel of mutations instead of for a single gene gives better sensitivity for diagnostic testing. In the first two studies that evaluated gene testing of preoperative cytology specimens by Cantara et al. and Nikiforov et al., a mutation was identified in 45% and 29%, respectively, of cytology results classified as indeterminate inclusive of the suspicious category, and molecular testing added diagnostic sensitivity and accuracy to cytology results [42,43]. Nikiforov et al. reported results from an independent and consecutive cohort of 513 indeterminate FNAB specimens that had prospective mutation testing (BRAF, RAS mutations, and PAX8‐PPARG, RET/PTC

Prognostic Utility Markers of aggressive thyroid cancer have often been synonymous with tumor dedifferentiation and these include mutations in p53 (25–

TABLE II. Test Performance for Commonly Used Molecular Tests in Indeterminate FNAB Results Reference [14] [16] [17] [18] [28] [44]

Test TSHR mRNA GEC GEC GEC MP MP

Specimens with histology evaluated, n 54 265 36 35 513 53

Sens 76 92 83 94 61 44

Spec 96 52 10 24 98 89

NPV 77 93 75 80 89 64

PPV 96 47 16 57 89 79

Malignancy rate 56 32 17 51 24 47

Missed cancers 

HCC, FVPTC, PTC FTC PTC FVPTC, PTC, FTC FVPTC, PTC

FTC, follicular thyroid cancer; FVPTC, follicular‐variant papillary thyroid cancer; GEC, gene expression classifier; HCC, Hurthle cell carcinoma; MP, mutation panel; NPV, negative predictive value; PD, poorly‐differentiated thyroid cancer; PTC, papillary thyroid cancer; sens, sensitivity; spec, specifiticy; PPV, positive predictive value.  Not reported.

Journal of Surgical Oncology

4

Yip

TABLE III. Clinical, Histologic and Molecular Predictors of Aggressive Differentiated Thyroid Cancer Clinical: Palpable and fixed thyroid mass Rapid growth Apparent lymph node metastasis Older age Distant metastasis Histologic: T4 tumor Extranodal metastasis Papillary thyroid cancer histologic variants: tall cell, columnar, diffuse sclerosing, and hobnail Widely invasive follicular thyroid cancer or follicular‐variant papillary thyroid cancer Incomplete resection Molecular: Presence of >1 driver mutation PIK3CA p53 CTNNB1 TERT promoter mutations

30%), PIK3CA (10–20%), CTNNB1 (10–20%), and AKT1 (5–10%) [23]. However, an emerging marker that is associated with aggressive differentiated thyroid cancer is mutation of the telomerase reverse transcriptase (TERT) promoter (Table III). Telomerase activation is a marker of malignancy that allows continued cell replication and TERT promoter mutations have been identified in other malignancies such as melanoma and glioblastomas. In thyroid cancers, TERT promoter mutations were identified in 7–22% of PTC and 35% of FTC, were often found in association with BRAF or RAS mutations, and were more likely in patients with histologically aggressive differentiated thyroid cancer [50,51]. In a series of 469 thyroid cancer patients of whom 402 had differentiated thyroid cancer, Melo et al. [52] reported that TERT promoter mutations were independently associated with an increased risk of disease‐specific mortality for both PTC and FTC patients. TERT promoter mutations were also identified in anaplastic and poorly‐ differentiated thyroid cancers [52]. BRAF V600E mutation has also been well studied as a possible prognostic biomarker for PTC. In a review by Xing et al. [53], BRAF mutations correlated with aggressive tumor characteristics such as extrathyroidal extension, advanced tumor stage at presentation, and lymph node or distant metastases. BRAF V600E has been shown to be an independent predictor of tumor recurrence [54] and the association may also be age‐related. In a cohort study, persistent/recurrent disease was most likely in PTC patients who had BRAF V600E‐positive tumors and who were age 65 years [55]. Elisei et al. examined 102 PTC patients over a median of 15 years with the BRAF V600E mutation was an independent risk factor for tumor‐related death [56]. More recently, Xing et al. evaluated a multi‐institutional and retrospective series of 1840 PTC patients with median follow‐up of 33 months, and observed an association between BRAF V600E and increased disease‐specific mortality. However in multivariate analysis, the effects of BRAF did not appear to be independent of extent of disease at presentation including presence of lymph node metastasis, extrathyroidal extension, and distant metastasis [24]. Therefore the utility of BRAF V600E testing may be greatest during preoperative planning and can be used to help determine the extent of initial surgery. Given the association with lymph node metastasis in particular, lymph node mapping by high‐resolution ultrasound should be performed prior to initial surgery. In the absence of clinical or sonographic lymph node involvement, current controversy exists on whether a prophylactic central compartment lymph node dissection (CCND) should be performed [57]. In single institution studies, prophylactic CCND reduced postoperative thyroglobulin Journal of Surgical Oncology

levels and may decrease local regional recurrence rates although no study has yet to demonstrate a reduction in disease‐specific mortality [58–61]. In addition, a higher rate of postoperative morbidity including temporary hypocalcemia has been observed even when the procedure was performed by high volume surgeons [60]. BRAF V600E positive PTC have a higher risk of central compartment lymph node metastasis and in multivariate analysis, BRAF remained a potent preoperative predictor of nodal disease [25,62]. Thus, preoperative BRAF V600E detection may be one way to identify patients who would best benefit from prophylactic CCND. A number of studies have also reported that BRAF V600E in papillary thyroid microcarcinomas (PTMC) correlated with higher rates of both extrathyroidal tumor extension and cervical lymph node metastasis [63,64]. The majority of PTMC are indolent tumors, are incidentally discovered during the removal of presumed large, benign neoplasms, and are almost universally cured by surgical resection. However, a subset of PTMC can behave aggressively leading to recurrence and mortality. In a molecular‐pathologic score derived from a cohort of PTMC then validated in an independent set of PTMC, BRAF V600E along with histopathologic features including fibrosis, superficial location, and intraglandular tumor spread/multifocality could predict PTMC at higher risk for aggressive behavior which was defined as lymph node metastasis or disease recurrence [65]. Multifocal PTC can be a result of either intraglandular spread from a single clonal lesion or >1 synchronous primary cancers. The mutation status and histologic characteristics of 60 multifocal PTC with two to four discrete tumor foci were analyzed [66]. As expected, BRAF mutations were found in 43% of tumors, RAS in 27%, and RET/PTC in 2%. Four patterns of multifocality were identified: (i) two foci containing different mutations (30%); (ii) one tumor with a mutation and another without mutations (32%); (iii) all foci containing the same mutation (25%); (iv) absence of detectable mutations in all foci (13%). Thus, up to 60% of multifocal PTC were likely synchronous primary tumors but up to 30% of cases had two different mutations and likely represented separate clonal cancers. On histopathology, these multifocal cancers were also located in different lobes, demonstrated distinct growth patterns, and showed no evidence of peritumoral dissemination [66].

Therapeutic Utility Distant metastatic disease occurs in up to 20% of DTC patients, is most commonly found in the lung and/or bone, and is often refractory to radioactive iodine (RAI) [67]. Loss of iodine avidity is a poor prognostic indicator with 10% long‐term survival rates. Cytotoxic chemotherapies such as doxorubicin had limited efficacy with significant toxicity [68,69]. With improved understanding of the genetic alterations involved in thyroid carcinogenesis, new options for advanced thyroid cancer patients have emerged including tyrosine kinase and small‐molecule inhibitors, and targeted inhibition of upregulated pathways to induce iodine reuptake [70–74] (Table IV). Tyrosine kinases have a pivotal role in tumor proliferation, angiogenesis, and metastasis. Tyrosine kinase inhibitors (TKI) non‐ specifically target these pro‐oncogenic kinases including VEGFR‐1, VEGFR‐2, EGFR, PDGFR, MET, FGFR, in addition to RAF and RET [75]. Subsequently, a number of studies have evaluated the role of TKI in advanced thyroid cancer patients (Table IV). In a phase II trial of motesanib for patients with progressive DTC, 14% had a partial response and 35% had disease stability. Motesanib was fairly well‐tolerated and 13% required treatment discontinuation due to adverse events including diarrhea, hypertension, fatigue, and weight loss [70]. Axitinib predominantly inhibits VEGF receptors but does not have activity on the RET kinase. Despite this, a 30% partial response to axitinib was observed in a phase II trial for patients with advanced or metastatic thyroid cancer (inclusive of DTC, MTC, and anaplastic thyroid cancer patients) [76]. Sunitinib inhibits VEGF receptors, RET, and RET/PTC 1 and 3, and complete responses have been observed for patients with

Molecular Markers in Thyroid Cancer

5

TABLE IV. Efficacy of Systemic Therapy for Radioactive Iodine Refractory Thyroid Cancer

Therapeutic agent Doxorubicin

Mechanism of action

Type of study

Outcome

Phase II [68]

37% PR

Motesanib

Cytotoxic chemotherapy Non‐specific TKI

Phase II [69]

Sunitinib Sorafenib

Non‐specific TKI Non‐specific TKI

Phase II [70] Phase III [71]

14% PR 35% SD 28% PR 12.2% PR

Vemurafenib

BRAF V600E small Phase I [72] molecular inhibitor

Selumetinib

Selective MEK Proof of principle [73] inhibitor to induce iodine reuptake

Common adverse effects Cardiomyopathy, acute arrhythmias, granulocytopenia, nausea, infertility, alopecia Diarrhea, hypertension, fatigue and weight loss Neutropenia, diarrhea, hand/foot syndrome, and leukopenia Hand/foot syndrome, diarrhea, alopecia, fatigue, weight loss, rash, anorexia, nausea

74% SD Median PFS ¼ 10.8 mo sorafenib vs 5.8 mo placebo HR 0.59, 95% CI 0.45–0.76, P < .001 3 patients: Cutaneous squamous cell carcinomas and keratoacanthomas, 1 pt w. PR rash, fatigue, arthralgias, nausea 2 pts w. SD 40% (8/20) treated with RAI Fatigue, rash, liver function test elevations 5 pts w. PR 3 pts w. SD

PFS, progression free survival; PR, partial response; SD, stable disease; TKI, tyrosine kinase inhibitor.

FDG‐avid metastatic thyroid cancer. In phase II study, 28% of patients with RAI‐refractory metastatic DTC had a partial response that was assessable by avidity on FDG‐PET [71]. Common toxicities included neutropenia, diarrhea, hand/foot syndrome, and leukopenia. The DECISION trial is one of the only phase III study completed in patients with RAI‐refractory progressive thyroid cancer and used sorafenib at 400 mg BID [72]. The trial encompassed 77 centers in 18 countries, and 417 patients were enrolled. Eligibility criteria included adult patients (age  18) who had locally advanced and/or metastatic RAI‐refractory differentiated thyroid cancer, had evidence of progression within 14 months, and had not previously received targeted or cytotoxic therapy. Patients were randomized 1:1 and analyzed by intention‐to‐treat. Sorafenib was associated with improved median progression‐free survival (PFS) of 10.8 mo vs placebo 5.8 mo (HR 0.59, 95% CI 0.45–0.76, P < .001), and these improvements were observed in all tumor histologies. Partial responses were observed in 12.2% in the sorafenib group compared to 0.5% in the placebo group. Adverse events requiring dose reductions occurred in 66% of patients with hand/foot syndrome being the most common side effect. Secondary malignancies occurred in nine patients who were taking sorafenib (4%) and included squamous cell carcinomas of the skin, leukemia, and bladder cancer. Secondary malignancies were also observed in four patients who took placebo. A proportion of the tumor specimens were tested for BRAF and RAS mutations, and compared to placebo sorafenib improved PFS irrespective of mutation status [72]. For patients who fail sorafenib, salvage therapy with a different TKI can still be beneficial. In a study of 17 patients with metastatic, RAI‐ refractory DTC who failed initial sorafenib due to either tumor progression or medication intolerance, second‐line TKI therapy resulted in 41% having a partial response and 59% having stable disease. Thus, sorafenib failure did not necessarily predict tumor response to an alternative TKI [77]. Vemurafenib is a small‐molecular and specific inhibitor of BRAF V600E. For patients with BRAF V600E positive metastatic melanoma a phase I trial demonstrated promising clinical efficacy with a 56% response rate [78]. A phase I trial of vemurafenib was completed in three patients with metastatic PTC and one had a confirmed partial response while the other two patients had stable disease [73]. A unique side effect Journal of Surgical Oncology

of vemurafenib is the development of cutaneous squamous cell carcinomas and keratoacanthomas that can occur in up to 30% of patients who receive selective or nonselective BRAF inhibitors [79]. Additional trials are ongoing to further investigate the role of vemurafenib in BRAF V600E positive and RAI‐refractory thyroid cancer. Constitutive activation of the MAPK pathway by BRAF V600E resulted in loss of expression of iodide‐metabolizing genes in a number of in vitro studies [80–82]. Suppression of the pathway then led to restoration of gene expression [81]. In a mouse model of inducible BRAF V600E expression in thyroid follicular cells, treatment with either MEK or BRAF small molecular inhibitors led to dramatic increases in RAI uptake [83]. These preclinical findings led rapidly to a trial evaluating the efficacy of selumetinib, a selective MEK1 and two inhibitors, to induce iodine reuptake in otherwise RAI‐refractory metastatic DTC patients [74]. After selumetinib treatment and demonstration of iodine uptake, 40% (8/20 study patients were able to receive a therapeutic dose of RAI. Decreases in serum thyroglobulin levels were observed in all treated patients and persisted for up to six months. Overall, five patients had a partial response and three patients had stable disease. Toxicity related to selumetinib was grade one or two. However one patient who had a large cumulative prestudy dose of RAI developed acute leukemia following study treatment. Tumor mutation status was also evaluated, and all five NRAS positive but only 1/9 BRAF positive thyroid cancers had iodine uptake following selumetinib treatment [74].

CIRCULATING MOLECULAR MARKERS TSHR mRNA may be a marker of malignancy, and can be detected using quantitative RT‐PCR when present in as few as 10 cancer cells per ml of peripheral blood. An elevated TSHR mRNA level >1 ng/mg was associated with 85% diagnostic accuracy in study of 54 patients with FNAB cytology classified as follicular neoplasm [14]. To optimize the diagnostic discriminancy, an algorithm was developed that incorporated nodule size (/¼ 65 years) are associated with recurrent papillary thyroid cancer. Ann Surg Oncol 2011;18:3566–3571. Elisei R, Ugolini C, Viola D, et al.: BRAF(V600E) mutation and outcome of patients with papillary thyroid carcinoma: A 15‐year median follow‐up study. J Clin Endocrinol Metab 2008;93:3943– 3949.

Journal of Surgical Oncology

7

57. American Thyroid Association Surgery Working G. American Association of Endocrine S. American Academy of O‐H. et al.: Consensus statement on the terminology and classification of central neck dissection for thyroid cancer. Thyroid 2009;19:1153–1158. 58. Hughes DT, White ML, Miller BS, et al.: Influence of prophylactic central lymph node dissection on postoperative thyroglobulin levels and radioiodine treatment in papillary thyroid cancer. Surgery 2010;148:1100–1106discussion 1006‐1107. 59. Popadich A, Levin O, Lee JC, et al.: A multicenter cohort study of total thyroidectomy and routine central lymph node dissection for cN0 papillary thyroid cancer. Surgery 2011;150:1048–1057. 60. Wang TS, Cheung K, Farrokhyar F, et al.: A meta‐analysis of the effect of prophylactic central compartment neck dissection on locoregional recurrence rates in patients with papillary thyroid cancer. Ann Surg Oncol 2013;20:3477–3483. 61. Lang BH, Wong KP, Wan KY, et al.: Impact of routine unilateral central neck dissection on preablative and postablative stimulated thyroglobulin levels after total thyroidectomy in papillary thyroid carcinoma. Ann Surg Oncol 2012;19:60–67. 62. Lee KC, Li C, Schneider EB, et al.: Is BRAF mutation associated with lymph node metastasis in patients with papillary thyroid cancer? Surgery 2012;152:977–983. 63. Rodolico V, Cabibi D, Pizzolanti G, et al.: BRAF V600E mutation and p27 kip1 expression in papillary carcinomas of the thyroid < or ¼ 1cm and their paired lymph node metastases. Cancer 2007;110:1218–1226. 64. Lupi C, Giannini R, Ugolini C, et al.: Association of BRAF V600E mutation with poor clinicopathological outcomes in 500 consecutive cases of papillary thyroid carcinoma. J Clin Endocrinol Metab 2007;92:4085–4090. 65. Niemeier LA, Kuffner Akatsu H, Song C, et al.: A combined molecular‐pathologic score improves risk stratification of thyroid papillary microcarcinoma. Cancer 2012;118:2069–2077. 66. Bansal M, Gandhi M, Ferris RL, et al.: Molecular and histopathologic characteristics of multifocal papillary thyroid carcinoma. Am J Surg Pathol 2013;37:1586–1591. 67. Shoup M, Stojadinovic A, Nissan A, et al.: Prognostic indicators of outcomes in patients with distant metastases from differentiated thyroid carcinoma. J Am Coll Surg 2003;197:191–197. 68. Sherman SI: Cytotoxic chemotherapy for differentiated thyroid carcinoma. Clin Oncol (R Coll Radiol) 2010;22:464–468. 69. Gottlieb JA, Hill CS Jr: Chemotherapy of thyroid cancer with adriamycin. Experience with 30 patients. N Engl J Med 1974; 290:193–197. 70. Sherman SI, Wirth LJ, Droz JP, et al.: Motesanib diphosphate in progressive differentiated thyroid cancer. N Engl J Med 2008; 359:31–42. 71. Carr LL, Mankoff DA, Goulart BH, et al.: Phase II study of daily sunitinib in FDG‐PET‐positive, iodine‐refractory differentiated thyroid cancer and metastatic medullary carcinoma of the thyroid with functional imaging correlation. Clin Cancer Res 2010;16:5260–5268. 72. Brose MS, Nutting CM, Jarzab B, et al.: Sorafenib in radioactive iodine‐refractory, locally advanced or metastatic differentiated thyroid cancer: A randomised, double‐blind, phase 3 trial. Lancet 2014. 73. Kim KB, Cabanillas ME, Lazar AJ, et al.: Clinical responses to vemurafenib in patients with metastatic papillary thyroid cancer harboring BRAF(V600E) mutation. Thyroid 2013;23:1277–1283. 74. Ho AL, Grewal RK, Leboeuf R, et al.: Selumetinib‐enhanced radioiodine uptake in advanced thyroid cancer. N Engl J Med 2013;368:623–632. 75. Sherman SI: Tyrosine kinase inhibitors and the thyroid. Best Pract Res Clin Endocrinol Metab 2009;23:713–722. 76. Cohen EE, Rosen LS, Vokes EE, et al.: Axitinib is an active treatment for all histologic subtypes of advanced thyroid cancer: Results from a phase II study. J Clin Oncol 2008;26:4708–4713. 77. Dadu R, Devine C, Hernandez M, et al.: Role of salvage targeted therapy in differentiated thyroid cancer patients who failed first‐line sorafenib. J Clin Endocrinol Metab 2014;jc20133588. 78. Flaherty KT, Puzanov I, Kim KB, et al.: Inhibition of mutated, activated BRAF in metastatic melanoma. N Engl J Med 2010;363:809–819.

8

Yip

79. Boussemart L, Routier E, Mateus C, et al.: Prospective study of cutaneous side‐effects associated with the BRAF inhibitor vemurafenib: A study of 42 patients. Ann Oncol 2013;24:1691–1697. 80. Durante C, Puxeddu E, Ferretti E, et al.: BRAF mutations in papillary thyroid carcinomas inhibit genes involved in iodine metabolism. J Clin Endocrinol Metab 2007;92:2840–2843. 81. Liu D, Hu S, Hou P, et al.: Suppression of BRAF/MEK/MAP kinase pathway restores expression of iodide‐metabolizing genes in thyroid cells expressing the V600E BRAF mutant. Clin Cancer Res 2007;13:1341–1349. 82. Riesco‐Eizaguirre G, Gutierrez‐Martinez P, Garcia‐Cabezas MA, et al.: The oncogene BRAF V600E is associated with a high risk of

Journal of Surgical Oncology

recurrence and less differentiated papillary thyroid carcinoma due to the impairment of Na þ/I‐ targeting to the membrane. Endocr Relat Cancer 2006;13:257–269. 83. Chakravarty D, Santos E, Ryder M, et al.: Small‐molecule MAPK inhibitors restore radioiodine incorporation in mouse thyroid cancers with conditional BRAF activation. J Clin Invest 2011;121:4700–4711. 84. Chia SY, Milas M, Reddy SK, et al.: Thyroid‐stimulating hormone receptor messenger ribonucleic acid measurement in blood as a marker for circulating thyroid cancer cells and its role in the preoperative diagnosis of thyroid cancer. J Clin Endocrinol Metab 2007;92:468–475.

Molecular markers for thyroid cancer diagnosis, prognosis, and targeted therapy.

Molecular markers including gene expression profiles, somatic gene alterations, and circulating peripheral markers have augmented diagnostic, prognost...
117KB Sizes 0 Downloads 7 Views