Information for Clinicians: Approach to the Patient with Progressive Radioiodine-Refractory Thyroid Cancer-When to Use Systemic Therapy

Radioactive Iodine in Differentiated Thyroid Carcinoma: A Systematic AGREE II Clinical Practice Guideline Appraisal

OBJECTIVE

Identify and appraise clinical practice guidelines (CPGs) for radioactive iodine (RAI) indications in differentiated thyroid carcinoma (DTC), and the treatment for radioactive iodine refractory (RAI-R) DTC using the Appraisal of Guidelines for Research and Evaluation II tool.

DATA SOURCES

MEDLINE (Pubmed), Ovid (EMBASE), and Scopus.

REVIEW METHODS

A systematic literature search was conducted to identify CPGs addressing RAI in DTC. CPGs were appraised by 4 independent reviewers in 6 distinct areas of quality. Scaled domain scores were subsequently calculated for each domain. Intraclass correlation coefficients were calculated for each domain to assess interrater reliability.

RESULTS

Sixteen guidelines were found addressing RAI indications for DTC. Of these 16, 9 also addressed the treatment of RAI-R DTC. A further 6 unique guidelines were identified that exclusively address RAI-R DTC, bringing the total number of guidelines to 22. The American Thyroid Association (ATA) guidelines for adult thyroid cancer were the highest scoring with a mean score of 83.5%. Two guidelines scored >60% in 5 or more domains, qualifying as "high" quality: ATA and British Thyroid Association. The highest scoring domain was domain 4: clarity of presentation (80.4%) while the lowest scoring domain was domain 5: applicability (38.6%).

CONCLUSION

Of the 22 guidelines identified, only two were "high quality." CPGs exclusively addressing the treatment of RAI-R DTC were weak with most guidelines scoring in the "low" quality range. This report reveals an unmet need for rigorously developed guidelines addressing indications for RAI in DTC, as well as the treatment for RAI-R DTC.

Ubiquitin conjugating enzyme E2 C (UBE2C) may play a dual role involved in the progression of thyroid carcinoma

The present study aimed to explore the role of ubiquitin-conjugating enzyme E2 C (UBE2C) in the progress of thyroid carcinoma (THCA). We firstly explored the prognostic impact and expression level of UBE2C in THCA. Then, we performed the UBE2C knockdown and evaluated the effects on the proliferation, cell cycle distribution, apoptosis, migration, and invasion of THCA cells, as well as resistance to sorafenib. Finally, we predicted the possible pathways and explored the correlation between UBE2C with immune infiltrates. The results showed that high expression of UBE2C independently predicted a shorter disease-free survival time of THCA patients. And UBE2C also presented a better prognostic performance on the survival probability of patients. Expression analysis showed that UBE2C was statistically upregulated in THCA tissue compared with normal tissue. After UBE2C knockdown, the proliferation of THCA cells was inhibited and apoptosis was increased. These results indicated that UBE2C acted as an oncogene in THCA. However, the migration and invasion of THCA cells with UBE2C knockdown were enhanced, and the expressions of migration-related proteins were upregulated. In addition, UBE2C knockdown increased the resistance of THCA cells to sorafenib. These results implied the potential of UBE2C as a suppressor gene in THCA. The pathway analysis further predicted that metabolism-related pathways were activated in the UBE2C low expression class, and cell growth and immune-related pathways were focused on the UBE2C high expression class. Finally, we observed a significant positive relationship between UBE2C and several immune infiltrates in THCA. It followed that UBE2C high expression might play a vital role in THCA to some extent. This study revealed that UBE2C participated in the progression of THCA and may play the dual role of both oncogene and tumor suppressor gene. The detailed mechanism needed to be further investigated.

Radioiodine Refractory Differentiated Thyroid Cancer

Patients with radioactive iodine (RAI) refractory locally advanced or metastatic differentiated thyroid cancer have a poor prognosis. This article reviews the definition of RAI-refractory thyroid cancer and the management approach. Watchful waiting should be considered for patients with asymptomatic and non-progressive disease, while oral targeted agent with tyrosine kinase inhibitors can be considered for patients who are symptomatic or whose disease would cause irreversible complications if treatment has not been initiated. Since these targeted agents only improve disease-free survival and are associated with adverse events, physicians should assess both clinical and tumor factors carefully to decide on the right timing of start of palliative treatment.

Progress in Treating Advanced Thyroid Cancers in the Era of Targeted Therapy

Background: Thyroid cancer is a common malignancy whose detection has increased significantly in past decades. Most of the increased incidence is due to detection of early well-differentiated thyroid cancer, but the incidence of more advanced thyroid cancers has increased as well. Recent methodological advancements have allowed for a deep understanding of the molecular underpinnings of the various types of thyroid cancer. Summary: Thyroid cancers harbor a high frequency of potential druggable molecular alterations, including the highest frequency of oncogenic driver kinase fusions seen across all solid tumors. Analyses of poorly differentiated and anaplastic thyroid carcinoma confirmed that these tumors develop from more well-differentiated follicular-derived thyroid cancers through acquired additional mutations. The recognition of driver genomic alterations in thyroid cancers not only predicts tumor phenotype but also now can inform treatment approaches. Conclusions: Major progress in understanding the oncogenic molecular underpinnings across the array of thyroid cancers has led to considerable gains in gene-specific systemic therapies for many cancers. This article focuses on the molecular characteristics of aggressive follicular-derived thyroid cancers and medullary thyroid cancer and highlights advancements in treating thyroid cancer in the era of targeted therapy.

Canadian consensus statement on the management of radioactive iodine-resistant differentiated thyroid cancer

Radioactive iodine-resistant differentiated thyroid cancer (RAIRTC) is an aggressive form of thyroid cancer that is uncommon and heterogeneous in its clinical behavior. With the emergence of more effective systemic therapy, the need for guidance in decision-making was recognized and a consensus committee of national experts was assembled. The consensus committee consisted of 13 clinicians involved in treating RAIRTC from across Canada and included endocrinologists, nuclear medicine physicians, surgeons, and radiation and medical oncologists. Domains of interest were identified by consensus, and evidence gathered using systematic reviews. Consensus recommendations for the diagnosis and management of RAIRTC were developed. It was recognized that the rarity of RAIRTC in practice and heterogeneous patterns of thyroid cancer care could limit access to effective therapy for some RAIRTC patients. This document offers guidance to manage RAIRTC patients in a multidisciplinary manner.

2019 European Thyroid Association Guidelines for the Treatment and Follow-Up of Advanced Radioiodine-Refractory Thyroid Cancer

The vast majority of thyroid cancers of follicular origin (TC) have a very favourable outcome, but 5-10% of cases will develop metastatic disease. Around 60-70% of this subset, hence less than 5% of all patients with TC, will become radioiodine refractory (RAI-R), with a significant negative impact on prognosis and a mean life expectancy of 3-5 years. Since no European expert consensus or guidance for this challenging condition is currently available, a task force of TC experts was nominated by the European Thyroid Association (ETA) to prepare this document based on the principles of clinical evidence. The task force started to work in September 2018 and after several revision rounds, prepared a list of recommendations to support the treatment and follow-up of patients with advanced TC. Criteria for advanced RAI-R TC were proposed, and the most appropriate diagnostic tools and the local, systemic and palliative treatments are described. Systemic therapy with multikinase inhibitors is fully discussed, including recommendations on how to start it and at which dosage, on the duration of treatment, and on the management of side effects. The appropriate relationship between the specialist and the patient/family as well as ethical issues are covered. Based on the available studies and on personal experience, the experts provided 39 recommendations aimed to improve the management of advanced RAI-R TCs. Above all of them is the indication to treat and follow these patients in a specialized setting which allows the interaction between several specialists in a multidisciplinary team.

CITED1 contributes to the progression of papillary thyroid carcinoma via the Wnt/β-catenin signaling pathway

Purpose

The incidence rate of thyroid cancer, the most common endocrine malignancy, has increased rapidly over the past 10 years. However, the fundamental molecular mechanisms underlying the malignant progression of thyroid cancer are unclear.

Materials and methods

Firstly, quantitative real-time PCR analysis and Western blot analysis were used to investigate the expression of Cbp/p300 interacting transactivator with Glu/Asp rich carboxy-terminal domain 1 (CITED1) in papillary thyroid carcinoma (PTC) cell lines. Then, we investigated the effects of CITED1 knockdown on cell proliferation, apoptosis, and invasion in in vitro and in vivo models of PTC.

Results

CITED1 was upregulated in PTC cell lines, and CITED1 knockdown significantly suppressed the proliferation, migration, and invasion of K1 cells resulting in a G0/G1 phase block. Furthermore, the silencing of CITED1 significantly promoted cell apoptosis. In the in vivo study, the growth speed and weight of the transplanted tumor were significantly suppressed in nude mice infected with short hairpin RNA targeting CITED1 (CITE1-shRNA) cells. Furthermore, we found that CITED1-shRNA activated Wnt/β-catenin signaling in PTC.

Conclusion

Taken together, our findings suggest that CITED1 knockdown facilitates apoptosis and inhibits proliferation and invasion in K1 cells via the Wnt/β-catenin signaling pathway.

AXL Is a Novel Predictive Factor and Therapeutic Target for Radioactive Iodine Refractory Thyroid Cancer

Papillary thyroid carcinomas (PTCs) have an excellent prognosis, but a fraction of them show aggressive behavior, becoming radioiodine (RAI)-resistant and/or metastatic. AXL (Anexelekto) is a tyrosine kinase receptor regulating viability, invasiveness and chemoresistance in various human cancers, including PTCs. Here, we analyze the role of AXL in PTC prognosis and as a marker of RAI refractoriness. Immunohistochemistry was used to assess AXL positivity in a cohort of human PTC samples. Normal and cancerous thyroid cell lines were used in vitro for signaling, survival and RAI uptake evaluations. 38.2% of human PTCs displayed high expression of AXL that positively correlated with RAI-refractoriness and disease persistence or recurrence, especially when combined with v-raf murine sarcoma viral oncogene homolog B(BRAF) V600E mutation. In human PTC samples, AXL expression correlated with V-akt murine thymoma viral oncogene homolog 1 (AKT1) and p65 nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) activation levels. Consistently, AXL stimulation with its ligand growth arrest-specific gene 6 (GAS6) increased AKT1- and p65 NF-kB-phosphorylation and promoted survival of thyroid cancer cell lines in culture. Enforced expression or activation of AXL in normal rat thyroid cells significantly reduced the expression of the sodium/iodide symporter (NIS) and the radioiodine uptake. These data indicate that AXL expression levels could be used as predictor of RAI refractoriness and as a possible novel therapeutic target of RAI resistant PTCs.

Controversies, Consensus, and Collaboration in the Use of 131I Therapy in Differentiated Thyroid Cancer: A Joint Statement from the American Thyroid Association, the European Association of Nuclear Medicine, the Society of Nuclear Medicine and Molecular Imaging, and the European Thyroid Association

BACKGROUND

Publication of the 2015 American Thyroid Association (ATA) management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer was met with disagreement by the extended nuclear medicine community with regard to some of the recommendations related to the diagnostic and therapeutic use of radioiodine (¹³¹I). Because of these concerns, the European Association of Nuclear Medicine and the Society of Nuclear Medicine and Molecular Imaging declined to endorse the ATA guidelines. As a result of these differences in opinion, patients and clinicians risk receiving conflicting advice with regard to several key thyroid cancer management issues.

SUMMARY

To address some of the differences in opinion and controversies associated with the therapeutic uses of ¹³¹I in differentiated thyroid cancer constructively, the ATA, the European Association of Nuclear Medicine, the Society of Nuclear Medicine and Molecular Imaging, and the European Thyroid Association each sent senior leadership and subject-matter experts to a two-day interactive meeting. The goals of this first meeting were to (i) formalize the dialogue and activities between the four societies; (ii) discuss indications for ¹³¹I adjuvant treatment; (iii) define the optimal prescribed activity of ¹³¹I for adjuvant treatment; and (iv) clarify the definition and classification of ¹³¹I-refractory thyroid cancer.

CONCLUSION

By fostering an open, productive, and evidence-based discussion, the Martinique meeting restored trust, confidence, and a sense of collegiality between individuals and organizations that are committed to optimal thyroid disease management. The result of this first meeting is a set of nine principles (The Martinique Principles) that (i) describe a commitment to proactive, purposeful, and inclusive interdisciplinary cooperation; (ii) define the goals of ¹³¹I therapy as remnant ablation, adjuvant treatment, or treatment of known disease; (iii) describe the importance of evaluating postoperative disease status and multiple other factors beyond clinicopathologic staging in ¹³¹I therapy decision making; (iv) recognize that the optimal administered activity of ¹³¹I adjuvant treatment cannot be definitely determined from the published literature; and (v) acknowledge that current definitions of ¹³¹I-refractory disease are suboptimal and do not represent definitive criteria to mandate whether ¹³¹I therapy should be recommended.

Radioiodine Refractory Differentiated Thyroid Cancer: Time to Update the Classifications

BACKGROUND

The management of aggressive and progressing metastatic differentiated thyroid cancer (DTC) is very difficult, and the determination as to when such patients are refractory to ¹³¹I therapy (e.g., radioiodine refractory) is problematic and controversial.

OBJECTIVE

The objective of this review is to discuss (i) the present major classifications of radioiodine refractory disease in DTC, (ii) factors that should be considered before designating a patient's DTC as radioiodine refractory, (iii) potential approaches and caveats to help manage and minimize a patient's exclusion from an ¹³¹I therapy that may have potential benefit in patients with aggressive and progressing metastatic DTC, (iv) next steps for revision of the classifications of radioiodine refractory DTC, and (v) areas for future research.

SUMMARY

To date, the classifications of radioiodine refractory DTC, although very useful, are not sacrosanct especially in the context of individualized patient management, and merely because a patient meets one or more of the various classifications, one should not consider by definition, fiat, or de facto that that a patient's DTC is radioiodine refractory. Rather, each patient should be individually managed with a good understanding of the limitations of the various classifications and potential approaches to help manage that patient. With awareness of the suggestions and caveats discussed herein and with assessment of the many other factors that affect the patient's specific clinical situation, the managing physician can deliver appropriate individualized patient care. A multi-organizational committee should be established as a standing committee to supervise and assist in the update of the classifications of radioiodine refractory DTC, including discussions of their limitations.

CONCLUSION

Classifications to help determine radioiodine refractory disease will continue to evolve as (i) more studies are published, (ii) managing physicians better understand the limitations and confounding factors of present classifications, and (iii) new agents either increase or reestablish ¹³¹I uptake.