Challenges associated with tyrosine kinase inhibitor therapy for metastatic thyroid cancer

Therapeutic advances of targeting receptor tyrosine kinases in cancer

Receptor tyrosine kinases (RTKs), a category of transmembrane receptors, have gained significant clinical attention in oncology due to their central role in cancer pathogenesis. Genetic alterations, including mutations, amplifications, and overexpression of certain RTKs, are critical in creating environments conducive to tumor development. Following their discovery, extensive research has revealed how RTK dysregulation contributes to oncogenesis, with many cancer subtypes showing dependency on aberrant RTK signaling for their proliferation, survival and progression. These findings paved the way for targeted therapies that aim to inhibit crucial biological pathways in cancer. As a result, RTKs have emerged as primary targets in anticancer therapeutic development. Over the past two decades, this has led to the synthesis and clinical validation of numerous small molecule tyrosine kinase inhibitors (TKIs), now effectively utilized in treating various cancer types. In this manuscript we aim to provide a comprehensive understanding of the RTKs in the context of cancer. We explored the various alterations and overexpression of specific receptors across different malignancies, with special attention dedicated to the examination of current RTK inhibitors, highlighting their role as potential targeted therapies. By integrating the latest research findings and clinical evidence, we seek to elucidate the pivotal role of RTKs in cancer biology and the therapeutic efficacy of RTK inhibition with promising treatment outcomes.

Tyrosine kinase inhibitors for radioiodine refractory differentiated thyroid cancer: A systematic review and meta-analysis

BACKGROUND

The poor overall prognosis of radioiodine refractory thyroid cancer is an inevitable challenge in managing this disease. A series of trials have demonstrated the antitumor activity of tyrosine kinase inhibitors (TKIs) in radioiodine refractory differentiated thyroid cancer (RAIR-DTC). However, the available evidence cannot determine the optimal choice of TKI in RAIR-DTC.

METHODS

This study searched PubMed, EMBASE, Cochrane databases, and the ClinicalTrials website. The Cochrane bias risk tool was used to assess the risk of bias, and to evaluate randomized clinical trials (RCT) of RAIR-DTC patients treated with the TKI system. Outcomes, including progression-free survival (PFS), overall survival (OS), and adverse events (AEs) were reported.

RESULTS

Seven studies involving 1310 patients with RAIR-DTC was conducted to compare the PFS and OS of various TKI monotherapies with placebo. The results showed that all TKI monotherapies had a statistically significant benefit in terms of PFS compared with placebo, with lenvatinib demonstrating the greatest benefit (hazard ratio [HR] 0.19, 95% credible interval [CrI] 0.14-0.25). In terms of OS, only apatinib (HR 0.42, 95% CrI 0.18-0.97) and anlotinib (HR 0.36, 95% CrI 0.18-0.73) showed statistically significant benefits compared with placebo. TKIs also had a higher incidence of AEs of grade 3 or higher compared with placebo. The findings suggest that lenvatinib may be the preferred TKI for the treatment of RAIR-DTC, although its high incidence of AEs should be considered. The results also indicate that TKI treatment may be similarly effective in RAIR-DTC patients with BRAF or RAS mutations and in those with papillary or follicular subtypes of the disease, regardless of prior TKI treatment.

CONCLUSIONS

The results of this meta-analysis suggest that targeted therapy with TKIs may be beneficial for patients with radioiodine-refractory advanced or metastatic differentiated thyroid cancer. Among the TKIs analyzed, lenvatinib appeared to be the most effective at improving PFS, although it also had the highest incidence of AEs. Further research through direct randomized controlled trials is needed to determine the optimal choice of TKI for treating patients with RAIR-DTC. This study is beneficial for formulating patients' treatment plans and guides clinicians' decision-making.

Proteinuria reduction with SGLT2 inhibitors in a patient treated with tyrosine kinase inhibitor lenvatinib

We describe the case of a 66-year-old woman treated with tyrosine kinase inhibitor Lenvatinib for thyroid carcinoma who had persistent proteinuria above 2 g/24 h despite maximal dose of angiotensin-converting enzyme inhibitor. We initiated a treatment with SGLT2 inhibitor Dapagliflozin. Three months after Dapagliflozin initiation, her proteinuria decreased to 1 g/24 h, and after 6 months of follow-up was 0.6 g/24 h. To our knowledge, this is the first case of successful proteinuria reduction with SGLT2i in a patient treated with Lenvatinib. Specific renal effects of SGLT2i seem promising and their effects on tyrosine kinase inhibitor renal adverse effects need to be validated in clinical trials involving cancer patients.

Adverse effects of tyrosine kinase inhibitors in cancer therapy: pathophysiology, mechanisms and clinical management

Since their invention in the early 2000s, tyrosine kinase inhibitors (TKIs) have gained prominence as the most effective pathway-directed anti-cancer agents. TKIs have shown significant utility in the treatment of multiple hematological malignancies and solid tumors, including chronic myelogenous leukemia, non-small cell lung cancers, gastrointestinal stromal tumors, and HER2-positive breast cancers. Given their widespread applications, an increasing frequency of TKI-induced adverse effects has been reported. Although TKIs are known to affect multiple organs in the body including the lungs, liver, gastrointestinal tract, kidneys, thyroid, blood, and skin, cardiac involvement accounts for some of the most serious complications. The most frequently reported cardiovascular side effects range from hypertension, atrial fibrillation, reduced cardiac function, and heart failure to sudden death. The potential mechanisms of these side effects are unclear, leading to critical knowledge gaps in the development of effective therapy and treatment guidelines. There are limited data to infer the best clinical approaches for the early detection and therapeutic modulation of TKI-induced side effects, and universal consensus regarding various management guidelines is yet to be reached. In this state-of-the-art review, we examine multiple pre-clinical and clinical studies and curate evidence on the pathophysiology, mechanisms, and clinical management of these adverse reactions. We expect that this review will provide researchers and allied healthcare providers with the most up-to-date information on the pathophysiology, natural history, risk stratification, and management of emerging TKI-induced side effects in cancer patients.

A meta-analysis of the efficacy and toxicity of tyrosine kinase inhibitors in treating patients with different types of thyroid cancer: how to choose drugs appropriately?

PURPOSE OF REVIEW

Because the high risk of death and poor prognosis of patients with refractory thyroid cancer (TC), studies related to tyrosine kinase inhibitors (TKIs) in treating different types of refractory TC have gradually attracted attention. Thus, we conducted a meta-analysis of published randomized controlled trials and single-arm trials to evaluate tyrosine kinase inhibitors' efficacy and safety profile treatment in TC patients.

RECENT FINDINGS

The studies of 29 in 287 met the criteria, 9 were randomized controlled trials and 20 were single-arm trials, involving 11 TKIs (Apatinib, Anlotinib, Cabozantinib, Imatinib, Lenvatinib, Motesanib, Pazopanib, Sorafenib, Sunitinib, Vandetanib, Vemurafenib). Treatment with TKIs significantly improved progression-free survival [hazard ratio [HR] 0.34 (95% confidence interval [CI]: 0.24, 0.48), P < 0.00001] and overall survival [OS] [HR 0.76, (95% CI: 0.64, 0.91), P = 0.003] in randomized controlled trials, but adverse events (AEs) were higher than those in the control group (P < 0.00001). The result of the objective response rate (ORR) in single-arm trials was statistically significant [odds ratio [OR] 0.49 (95% CI: 0.32, 0.75), P = 0.001].

SUMMARY

TKIs significantly prolonged progression-free survival and OS or improved ORR in patients with different types of TC (P < 0.01). Our recommendation is to select appropriate TKIs to treat different types of TC patients, and to prevent and manage drug-related AEs after using TKIs.

[Modern aspects influencing the management of patients with papillary thyroid cancer]

Thyroid cancer (TC) is the most common malignant tumor of the endocrine glands and accounts to 3% of the total structure of oncological morbidity. Papillary thyroid cancer (PTC) is the most common histological variant of thyroid malignancies. It accounts for about 85% of all cases of thyroid cancer. Despite good postoperative results and excellent survival compared to many other malignancies, tumor metastases to the paratracheal lymph nodes are quite common. This review of the literature considers the current personalized approach to patients with papillary thyroid cancer and current aspects influencing the management of patients with PTC.

Thyroid Carcinoma, Version 2.2022, NCCN Clinical Practice Guidelines in Oncology

Differentiated thyroid carcinomas is associated with an excellent prognosis. The treatment of choice for differentiated thyroid carcinoma is surgery, followed by radioactive iodine ablation (iodine-131) in select patients and thyroxine therapy in most patients. Surgery is also the main treatment for medullary thyroid carcinoma, and kinase inhibitors may be appropriate for select patients with recurrent or persistent disease that is not resectable. Anaplastic thyroid carcinoma is almost uniformly lethal, and iodine-131 imaging and radioactive iodine cannot be used. When systemic therapy is indicated, targeted therapy options are preferred. This article describes NCCN recommendations regarding management of medullary thyroid carcinoma and anaplastic thyroid carcinoma, and surgical management of differentiated thyroid carcinoma (papillary, follicular, Hürthle cell carcinoma).

Lenvatinib dose, efficacy, and safety in the treatment of multiple malignancies

INTRODUCTION

Lenvatinib is an oral multitargeted tyrosine kinase inhibitor that has shown efficacy and manageable safety across multiple cancer types. The recommended starting doses for lenvatinib differ across cancer types and indications based on whether it is used as monotherapy or as combination therapy.

AREAS COVERED

This review covers clinical trials that established the dosing paradigm and efficacy of lenvatinib and defined its adverse-event profile as a monotherapy; or in combination with the mTOR inhibitor, everolimus; or the anti-PD-1 antibody, pembrolizumab; and/or chemotherapy.

EXPERT OPINION

Lenvatinib has been established as standard-of-care either as a monotherapy or in combination with other anticancer agents for the treatment of radioiodine-refractory differentiated thyroid carcinoma, hepatocellular carcinoma, renal cell carcinoma, and endometrial carcinoma, and is being investigated further across several other tumor types. The dosing and adverse-event management strategies for lenvatinib have been developed through extensive clinical trial experience. Collectively, the data provide the rationale to start lenvatinib at the recommended doses and then interrupt or dose reduce as necessary to achieve required dose intensity for maximized patient benefit. The adverse-event profile of lenvatinib is consistent with that of other tyrosine kinase inhibitors, and clinicians are encouraged to review and adopt relevant symptom-management strategies.

Target Therapy in Thyroid Cancer: Current Challenge in Clinical Use of Tyrosine Kinase Inhibitors and Management of Side Effects

Thyroid cancer (TC) is the most common endocrine malignancy. TC is classified as differentiated TC (DTC), which includes papillary and follicular subtypes and Hürthle cell variants, medullary TC (MTC), anaplastic TC (ATC), and poorly differentiated TC (PDTC). The standard of care in DTC consists of surgery together with radioactive iodine (¹³¹I) therapy and thyroid hormone, but patients with MTC do not benefit from ¹³¹I therapy. Patients with advanced TC resistant to ¹³¹I treatment (RAI-R) have no chance of cure, as well as patients affected by ATC and progressive MTC, in which conventional therapy plays only a palliative role, representing, until a few years ago, an urgent unmet need. In the last decade, a better understanding of molecular pathways involved in the tumorigenesis of specific histopathological subtypes of TC has led to develop tyrosine kinase inhibitors (TKIs). TKIs represent a valid treatment in progressive advanced disease and were tested in all subtypes of TC, highlighting the need to improve progression-free survival. However, treatments using these novel therapeutics are often accompanied by side effects that required optimal management to minimize their toxicities and thereby enable patients who show benefit to continue treatment and obtain maximal clinical efficacy. The goal of this overview is to provide an update on the current use of the main drugs recently studied for advanced TC and the management of the adverse events.

Peptide Receptor Radionuclide Therapy in Thyroid Cancer

The treatment options that are currently available for management of metastatic, progressive radioactive iodine (RAI)-refractory differentiated thyroid cancers (DTCs), and medullary thyroid cancers (MTCs) are limited. While there are several systemic targeted therapies, such as tyrosine kinase inhibitors, that are being evaluated and implemented in the treatment of these cancers, such therapies are associated with serious, sometimes life-threatening, adverse events. Peptide receptor radionuclide therapy (PRRT) has the potential to be an effective and safe modality for treating patients with somatostatin receptor (SSTR)+ RAI-refractory DTCs and MTCs. MTCs and certain sub-types of RAI-refractory DTCs, such as Hürthle cell cancers which are less responsive to conventional modalities of treatment, have demonstrated a favorable response to treatment with PRRT. While the current literature offers hope for utilization of PRRT in thyroid cancer, several areas of this field remain to be investigated further, especially head-to-head comparisons with other systemic targeted therapies. In this review, we provide a comprehensive outlook on the current translational and clinical data on the use of various PRRTs, including diagnostic utility of somatostatin analogs, theranostic properties of PRRT, and the potential areas for future research.

Nursing Management and Adverse Events in Thyroid Cancer Treatments with Tyrosine Kinase Inhibitors. A Narrative Review

Simple Summary

Tyrosine kinase inhibitors are an effective and promising therapy in the treatment of advanced differentiated medullary thyroid cancers. The prevention and management of new adverse events of these drugs are important to keep patients on their treatment course, avoiding drug discontinuation or interruption, and are associated with a faster recovery of the disease. The contribution of a multidisciplinary team of healthcare professionals optimizes the management of adverse events, maximizing the benefits and reducing the risks of treatment, consequently improving the quality of life of patients.

Abstract

Background: The advent of multikinase inhibitors has changed the treatment of advanced, metastatic, unresectable thyroid cancers, refractory to available treatments. These drugs cause new adverse events that should be prevented and treated for long periods, and sometimes beyond their discontinuation. The purpose of this narrative review was the description, prevention, and nursing management of the most frequent adverse events of locally advanced or metastatic differentiated thyroid cancer with sorafenib and lenvatinib, and medullary Thyroid cancer with vandetanib and cabozantinib treatment. Methods: A narrative literature review. Results: Studies included in this narrative review suggest that over 90% of patients treated with tyrosine kinase inhibitors experience at least 1 adverse event of any grade affecting their quality of life. Patients treated with tyrosine kinase inhibitors experienced at least one adverse event at any grade in ≥90% of cases, with a higher incidence in the first 6–8 weeks of treatment. The most frequent adverse events that can affect a patients’ quality of life are dermatological, gastrointestinal, cardiovascular, and metabolic. Conclusions: Early assessment of risk factors and identification of adverse events can help nurses support these patients throughout their clinical-therapeutic pathway, increasing the benefits of treatment and reducing reduction/discontinuation.

Management of VEGFR-Targeted TKI for Thyroid Cancer

Recent advances in the development of multitarget tyrosine kinase inhibitors (MTKIs), which mainly target the vascular endothelial growth factor receptor (VEGFR), have improved prognoses and dramatically changed the treatment strategy for advanced thyroid cancer. However, adverse events related to this inhibition can interrupt treatment and sometimes lead to discontinuation. In addition, they can be annoying and potentially jeopardize the subjects' quality of life, even allowing that the clinical outcome of patients with advanced thyroid cancer remains limited. In this review, we summarize the potential mechanisms underlying these adverse events (hypertension, proteinuria and renal impairment, hemorrhage, fistula formation/gastrointestinal perforation, wound healing, cardiovascular toxicities, hematological toxicity, diarrhea, fatigue, and acute cholecystitis), their characteristics, and actual management. Furthermore, we also discuss the importance of related factors, including alternative treatments that target other pathways, the necessity of subject selection for safer administration, and patient education.

Clinical efficacy of lenvatinib for the treatment of radioiodine-refractory thyroid carcinoma: A systematic review and meta-analysis of clinical trials

OBJECTIVE

To evaluate the efficacy of lenvatinib in the treatment of radioiodine-refractory thyroid carcinoma.

BACKGROUND

Thyroid carcinoma is one of the top ten carcinomas worldwide. Clinically, thyroid cancers are managed with resections and adjuvant therapy with radioiodine. However, radioiodine is not effective for radioiodine-refractory (RR) thyroid carcinoma in some patients. Lenvatinib is a multi-kinase inhibitor for the treatment of RR thyroid carcinoma. Several clinical trials showed its efficacy in prolonging progression-free survival (PFS) and overall survival (OS).

DESIGN, PATIENTS AND MEASUREMENTS

A systematic search was done on databases (PubMed, Embase, MEDLINE, Cochrane) on 8 June 2020. Search keywords were lenvatinib, thyroid carcinoma and randomized controlled trials. Clinical trials fulfilling the SELECT protocol were selected to evaluate the efficacy of lenvatinib in terms of prolongation of PFS, OS and objective response rate (ORR). The risk ratio and distribution of grade 3 or above adverse events were documented.

RESULTS

Of the 3997 patients of mean age 62.5 years in fifteen selected studies, lenvatinib is associated with prolonged PFS (hazard ratio 0.24, 95% CI, 0.19-0.31, p < .001) and OS (hazard ratio 0.65, 95% CI, 0.52-0.81, p < .001). Compared with placebo, the risk ratio of ORR and incidence of grade 3 or above adverse events are 35.41 (95% CI, 19.42-64.58, p < .001) and 8.25 (95% CI, 6.50-10.46, p < .001), respectively. Subgroup analysis shows that lenvatinib is effective for all patients with RR thyroid carcinoma, regardless of age, histological subtypes, radiological subtypes and mutation status.

CONCLUSION

Lenvatinib is effective in the treatment of RR thyroid carcinoma. Close monitoring of serious adverse events is recommended.

The intratumor microbiome predicts prognosis across gender and subtypes in papillary thyroid carcinoma

While the intratumor microbiome has become increasingly implicated in cancer development, the microbial landscape of papillary thyroid carcinoma (PTC) is essentially uninvestigated. PTC is characterized by varied prognosis between gender and cancer subtype, but the cause for gender and subtype-based dissimilarities is unclear. Women are more frequently diagnosed with PTC, while men suffer more advanced-staged PTC. In addition, tall cell variants are more aggressive than classical and follicular variants of PTC. We hypothesized that intratumor microbiome composition distinctly alters the immune landscape and predicts clinical outcome between PTC subtypes and between patient genders. Raw whole-transcriptome RNA-sequencing, Level 3 normalized mRNA expression read counts, and DNA methylation 450 k sequencing data for untreated, nonirradiated tumor, and adjacent normal tissue were downloaded from the Genomic Data Commons (GDC) legacy archive for 563 thyroid carcinoma patients. Microbe counts were extracted using Pathoscope 2.0 software. We correlated microbe abundance to clinical variables and immune-associated gene expression. Gene-set enrichment, mutation, and methylation analyses were conducted to correlate microbe abundance to characterize microbes' roles. Overall, PTC tumor tissue significantly lacked microbes that are populated in adjacent normal tissue, which suggests presence of microbes may be critical in controlling immune cell expression and regulating immune and cancer pathways to mitigate cancer growth. In contrast, we also found that microbes distinctly abundant in tall cell and male patient cohorts were also correlated with higher mutation expression and methylation of tumor suppressors. Microbe dysbiosis in specific PTC types may explain observable differences in PTC progression and pathogenesis. These microbes provide a basis for developing specialized prebiotic and probiotic treatments for varied PTC tumors.

KRAS G12V Mutation in Acquired Resistance to Combined BRAF and MEK Inhibition in Papillary Thyroid Cancer

BRAF V600E mutations occur in approximately 40% of all patients with papillary thyroid cancer (PTC) and are associated with a worse prognosis in population studies. Treatment with single-agent BRAF inhibitors can result in nondurable partial responses (PRs) in clinical trials, but resistance inevitably develops. The mechanisms of resistance are not completely understood, but in non-thyroid tumors harboring BRAF V600E mutations, resistance has been ascribed to concurrent or acquired mutations in MEK1/2, RAC1, KRAS, and NRAS. This case report describes a patient with radioactive iodine-refractory metastatic PTC treated in a clinical trial with combination BRAF and MEK inhibition who achieved a durable PR. At time of progression, biopsy revealed an acquired KRAS G12V-activating mutation. The patient subsequently went on to have a PR to cabozantinib therapy in the clinical trial. This is the first reported case of an acquired KRAS-activating mutation that developed during treatment with BRAF and MEK inhibition in a patient with BRAF-mutated PTC. The KRAS mutation was also detected in peripheral blood samples taken as part of the trial, indicating that resistant mutations may be identified through noninvasive means. The identification of resistant mutations in patients at time of progression is necessary to identify possible therapeutic options including potential clinical trials.ClinicalTrials.gov identifier: NCT01723202.

Lenvatinib and sorafenib for differentiated thyroid cancer after radioactive iodine: a systematic review and economic evaluation

BACKGROUND

Thyroid cancer is a rare cancer, accounting for only 1% of all malignancies in England and Wales. Differentiated thyroid cancer (DTC) accounts for ≈94% of all thyroid cancers. Patients with DTC often require treatment with radioactive iodine. Treatment for DTC that is refractory to radioactive iodine [radioactive iodine-refractory DTC (RR-DTC)] is often limited to best supportive care (BSC).

OBJECTIVES

We aimed to assess the clinical effectiveness and cost-effectiveness of lenvatinib (Lenvima®; Eisai Ltd, Hertfordshire, UK) and sorafenib (Nexar®; Bayer HealthCare, Leverkusen, Germany) for the treatment of patients with RR-DTC.

DATA SOURCES

EMBASE, MEDLINE, PubMed, The Cochrane Library and EconLit were searched (date range 1999 to 10 January 2017; searched on 10 January 2017). The bibliographies of retrieved citations were also examined.

REVIEW METHODS

We searched for randomised controlled trials (RCTs), systematic reviews, prospective observational studies and economic evaluations of lenvatinib or sorafenib. In the absence of relevant economic evaluations, we constructed a de novo economic model to compare the cost-effectiveness of lenvatinib and sorafenib with that of BSC.

RESULTS

Two RCTs were identified: SELECT (Study of [E7080] LEnvatinib in 131I-refractory differentiated Cancer of the Thyroid) and DECISION (StuDy of sorafEnib in loCally advanced or metastatIc patientS with radioactive Iodine-refractory thyrOid caNcer). Lenvatinib and sorafenib were both reported to improve median progression-free survival (PFS) compared with placebo: 18.3 months (lenvatinib) vs. 3.6 months (placebo) and 10.8 months (sorafenib) vs. 5.8 months (placebo). Patient crossover was high (≥ 75%) in both trials, confounding estimates of overall survival (OS). Using OS data adjusted for crossover, trial authors reported a statistically significant improvement in OS for patients treated with lenvatinib compared with those given placebo (SELECT) but not for patients treated with sorafenib compared with those given placebo (DECISION). Both lenvatinib and sorafenib increased the incidence of adverse events (AEs), and dose reductions were required (for > 60% of patients). The results from nine prospective observational studies and 13 systematic reviews of lenvatinib or sorafenib were broadly comparable to those from the RCTs. Health-related quality-of-life (HRQoL) data were collected only in DECISION. We considered the feasibility of comparing lenvatinib with sorafenib via an indirect comparison but concluded that this would not be appropriate because of differences in trial and participant characteristics, risk profiles of the participants in the placebo arms and because the proportional hazard assumption was violated for five of the six survival outcomes available from the trials. In the base-case economic analysis, using list prices only, the cost-effectiveness comparison of lenvatinib versus BSC yields an incremental cost-effectiveness ratio (ICER) per quality-adjusted life-year (QALY) gained of £65,872, and the comparison of sorafenib versus BSC yields an ICER of £85,644 per QALY gained. The deterministic sensitivity analyses show that none of the variations lowered the base-case ICERs to < £50,000 per QALY gained.

LIMITATIONS

We consider that it is not possible to compare the clinical effectiveness or cost-effectiveness of lenvatinib and sorafenib.

CONCLUSIONS

Compared with placebo/BSC, treatment with lenvatinib or sorafenib results in an improvement in PFS, objective tumour response rate and possibly OS, but dose modifications were required to treat AEs. Both treatments exhibit estimated ICERs of > £50,000 per QALY gained. Further research should include examination of the effects of lenvatinib, sorafenib and BSC (including HRQoL) for both symptomatic and asymptomatic patients, and the positioning of treatments in the treatment pathway.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42017055516.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Extended Real-World Observation of Patients Treated with Sorafenib for Radioactive Iodine-Refractory Differentiated Thyroid Carcinoma and Impact of Lenvatinib Salvage Treatment: A Korean Multicenter Study

Background: Treatment for patients with radioactive iodine (RAI)-refractory differentiated thyroid carcinoma (DTC) is challenging. Recently, two tyrosine kinase inhibitors (sorafenib and lenvatinib) have been approved and showed benefits for progression-free survival with tolerable adverse events. Methods: This is an extension study of a previous multicenter, retrospective cohort study of real-world experience in treating 98 patients with progressive RAI-refractory DTC with sorafenib. The primary endpoint was overall survival (OS). The efficacy of lenvatinib as salvage therapy after disease progression on first-line sorafenib was evaluated by comparing outcomes in 32 patients who were treated with lenvatinib with 41 patients who were not and therefore served as a no salvage treatment group. Results: The median OS of all 98 patients treated with sorafenib was 41.5 months, and the median progression-free survival was 13.5 months. Patients without disease-related symptoms before sorafenib treatment had better OS than those with symptoms (hazard ratio [HR] = 0.56 [95% confidence interval, CI 0.31-0.99], p = 0.048). Larger tumor size was associated with a minimally increased risk of death (HR = 1.02 [CI 1.00-1.03], p = 0.049). Best tumor response was not associated with OS (p = 0.490). Lenvatinib salvage treatment significantly improved OS in patients receiving it compared with those who did not (HR = 0.28 [CI 0.15-0.53], p < 0.001). The median OS from the time of disease progression after first-line sorafenib treatment was 4.9 months in no salvage treatment group, whereas it was not reached in the lenvatinib salvage group. Conclusions: The absence of disease-related symptoms and smaller tumor burden was associated with survival benefits of first-line sorafenib treatment in patients with progressive RAI-refractory DTC. Lenvatinib salvage therapy was effective in improving OS in patients with disease progression after first-line sorafenib.

Rare complications of multikinase inhibitor treatment

OBJECTIVE

The advent of multikinase inhibitor (MKI) therapy has led to a radical change in the treatment of patients with advanced thyroid carcinoma. The aim of this manuscript is to communicate rare adverse events that occurred in less than 5% of patients in clinical trials in a subset of patients treated in our hospital.

SUBJECTS AND METHODS

Out of 760 patients with thyroid cancer followed up with in our Division of Endocrinology, 29 (3.8%) received treatment with MKIs. The median age at diagnosis of these patients was 53 years (range 20-70), and 75.9% of them were women. Sorafenib was prescribed as first-line treatment to 23 patients with differentiated thyroid cancer and as second-line treatment to one patient with advanced medullary thyroid cancer (MTC). Vandetanib was indicated as first-line treatment in 6 patients with MTC and lenvatinib as second-line treatment in two patients with progressive disease under sorafenib treatment.

RESULTS

During the follow-up of treatment (mean 13.7 ± 7 months, median 12 months, range 6-32), 5/29 (17.2%) patients presented rare adverse events. These rare adverse effects were: heart failure, thrombocytopenia, and squamous cell carcinoma during sorafenib therapy and squamous cell carcinoma and oophoritis with intestinal perforation during vandetanib treatment.

CONCLUSIONS

About 3 to 5 years after the approval of MKI therapy, we learned that MKIs usually lead to adverse effects in the majority of patients. Although most of them are manageable, we still need to be aware of potentially serious and rare or unreported adverse effects that can be life-threatening.

Managing the adverse events associated with lenvatinib therapy in radioiodine-refractory differentiated thyroid cancer

Lenvatinib is a multikinase inhibitor of vascular endothelial growth factor (VEGF) receptors 1-3, fibroblast growth factor receptors 1-4, RET, KIT, and platelet-derived growth factor receptor-α. Lenvatinib is approved as a monotherapy for the treatment of radioiodine-refractory differentiated thyroid cancer and in combination with everolimus for the second-line treatment of advanced renal cell carcinoma. Lenvatinib is also under investigation for the treatment of several malignancies including unresectable hepatocellular carcinoma. Although lenvatinib is associated with favorable efficacy, it is associated with adverse events (AEs) that the clinician will have to closely monitor for and proactively manage. Most of these AEs are known class effects of VEGF-targeted therapies, including hypertension, diarrhea, fatigue or asthenia, decreased appetite, and weight loss. This review summarizes the safety profile of lenvatinib and offers guidance for the management of both frequent and rare AEs. We discuss the potential mechanisms underlying these AEs and present practical recommendations for managing toxicities. The development of treatment plans that include prophylactic and therapeutic strategies for the management of lenvatinib-associated AEs has the potential to improve patient quality of life, optimize adherence, minimize the need for dose reductions, treatment interruptions, or discontinuations, and maximize patient outcomes.

Pazopanib, Cabozantinib, and Vandetanib in the Treatment of Progressive Medullary Thyroid Cancer with a Special Focus on the Adverse Effects on Hypertension

Medullary thyroid cancer (MTC) is a rare malignancy with a poor prognosis. First line therapy is surgery, which is the only curative method of the disease. However, in non-operable cases or with tumor progression and metastases, a systemic treatment is necessary. This form of cancer is often insensitive to conventional chemotherapy, but the use of tyrosine kinase inhibitors (TKIs), such as pazopanib, cabozantinib, and vandetanib, has shown promising results with an increase in progression-free survival and prolonged lifetime. Therefore, we focused on the pharmacological characteristics of TKIs, their mechanism of action, their application as a secondary treatment option for MTC, their efficacy as a cancer drug treatment, and reviewed the ongoing clinical trials. TKIs also act systemically causing various adverse events (AEs). One common AE of this treatment is hypertension, known to be associated with cardiovascular disease and can therefore potentially worsen the well-being of the treated patients. The available treatment strategies of drug-induced hypertension were discussed. The mechanism behind the development of hypertension is still unclear. Therefore, the treatment of this AE remains symptomatic. Thus, future studies are necessary to investigate the link between tumor growth inhibition and hypertension. In addition, optimized, individual treatment strategies should be implemented.

Navigating Systemic Therapy in Advanced Thyroid Carcinoma: From Standard of Care to Personalized Therapy and Beyond

Thyroid cancer, with the exception of anaplastic thyroid cancer, typically has very favorable outcomes with the standard therapy. However, those that persist, recur, or metastasize are associated with a worse prognosis. Targeted therapy with kinase inhibitors has shown promise in advanced cases of thyroid cancer, and currently five drug regimens are approved for use in clinical practice in the treatment of differentiated, medullary, and anaplastic thyroid cancer, with more options in the pipeline. However, one of the greatest dilemmas is when and how to initiate one of these drugs, and this is discussed herein.

Targeted Therapy for Medullary Thyroid Cancer: A Review

Medullary thyroid cancers (MTCs) constitute between 2 and 5% of all thyroid cancers. The 10-year overall survival (OS) rate of patients with localized disease is around 95% while that of patients with regional stage disease is about 75%. Only 20% of patients with distant metastases at diagnosis survive 10 years which is significantly lower than for differentiated thyroid cancers. Cases with regional metastases at presentation have high recurrence rates. Adjuvant external radiation confers local control but not improved OS. The management of residual, recurrent, or metastatic disease till a few years ago was re-surgery with local measures such as radiation. Chemotherapy was used with marginal benefit. The development of targeted therapy has brought in a major advantage in management of such patients. Two drugs—vandetanib and cabozantinib—have been approved for use in progressive or metastatic MTC. In addition, several drugs acting on other steps of the molecular pathway are being investigated with promising results. Targeted radionuclide therapy also provides an effective treatment option with good quality of life. This review covers the rationale of targeted therapy for MTC, present treatment options, drugs and methods under investigation, as well as an outline of the adverse effects and their management.

Biological Evaluation of a Fluorescent-Imaging Agent for Medullary Thyroid Cancer in an Orthotopic Model

Context

The primary and definitive treatment of medullary thyroid cancer (MTC) is surgical resection. Recurrent or residual disease is typically a result of incomplete surgical removal.

Objective

Our objective is to develop a compound that assists in intraoperative visualization of cancer, which would have the potential to improve surgical cure rates and outcomes.

Results

We report the biological characterization of Compound-17, which is labeled with IRdye800, allowing fluorescent visualization of MTC mouse models. We found that the agent has high affinity for two human MTC cell lines (TT and MZ-CRC1) in vitro and in vivo. We further tested the affinity of the compound in a newly developed MTC orthotopic xenograft model and found that Compound-17 produces fluorescent signals within MTC-derived orthotopic xenografts in comparison with a sequence-jumbled control compound and surrounding normal tissues.

Conclusions

Compound-17 is a unique and effective molecule for MTC identification that may have therapeutic potential.

Incidence and timing of common adverse events in Lenvatinib-treated patients from the SELECT trial and their association with survival outcomes

PURPOSE

In the study of (E7080) lenvatinib in differentiated cancer of the thyroid, most patients experienced an adverse event. In this report, we examine common lenvatinib-emergent adverse events in this phase three, randomized, double-blind study.

METHODS

Adverse events were graded per Common Terminology Criteria for Adverse Events v4.0. 392 patients were enrolled (lenvatinib: 261, placebo: 131) and received lenvatinib 24 mg/day or placebo. The main outcome measures were: associations with progression-free survival and overall survival in exploratory univariate and multivariate analyses along with additional variables.

RESULTS

The most common any-grade adverse events (any grade; grade 3) in lenvatinib-treated patients included proteinuria (32%; 10%), diarrhea (67%; 9%), fatigue/asthenia/malaise (67%; 10%), rash (23%; 0.4%), and palmar-plantar erythrodysesthesia syndrome (33%; 3%). There were no grade 4 events for these adverse events. They generally occurred early (median time to first onset [weeks]: proteinuria [6.1], diarrhea [12.1], fatigue/asthenia/malaise [3.0], rash [7.3], and palmar-plantar erythrodysesthesia syndrome [5.9]), and were resolved primarily with dose modifications (median time to resolution [weeks]: proteinuria [8.8], diarrhea [18.1], fatigue/asthenia/malaise [16.3], rash [5.9], and palmar-plantar erythrodysesthesia syndrome [20.0]). Discontinuation due to these adverse events occurred in 2 (1%) patients with proteinuria and 4 (2%) with fatigue. Progression-free survival was not associated with any of the adverse events. Eastern Cooperative Oncology Group performance status (P = 0.001), follicular histology (P = 0.002), and diarrhea (P = 0.023) were associated with overall survival in multivariate analyses (median overall survival for patients with diarrhea: not reached; without: 17.1 months).

CONCLUSIONS

In the study of (E7080) lenvatinib in differentiated cancer of the thyroid, the most common adverse events typically occurred early and were primarily managed with dose modifications. Overall survival was significantly associated with diarrhea.

Radioactive iodine-refractory differentiated thyroid cancer: an uncommon but challenging situation

Radioiodine (RAI)-refractory thyroid cancer is an uncommon entity, occurring with an estimated incidence of 4-5 cases/year/million people. RAI refractoriness is more frequent in older patients, in those with large metastases, in poorly differentiated thyroid cancer, and in those tumors with high 18-fluordeoxyglucose uptake on PET/CT. These patients have a 10-year survival rate of less than 10%. In recent years, new therapeutic agents with molecular targets have become available, with multikinase inhibitors (MKIs) being the most investigated drugs. Two of these compounds, sorafenib and lenvatinib, have shown significant objective response rates and have significantly improved the progression-free survival in the two largest published prospective trials on MKI use. However, no overall survival benefit has been achieved yet. This is probably related to the crossover that occurs in most patients who progress on placebo treatment to the open treatment of these studies. In consequence, the challenge is to correctly identify which patients will benefit from these treatments. It is also crucial to understand the appropriate timing to initiate MKI treatment and when to stop it. The purpose of this article is to define RAI refractoriness, to summarize which therapies are available for this condition, and to review how to select patients who are suitable for them.

Pharmacogenomic Markers of Targeted Therapy Toxicity in Patients with Metastatic Renal Cell Carcinoma

BACKGROUND

Targeted therapy (TT) in metastatic renal cell carcinoma (mRCC) may be associated with a high rate of toxicity that undermines treatment efficacy and patient quality of life. Polymorphisms in genes involved in the pharmacokinetic pathways of TTs may predict toxicity.

OBJECTIVE

To investigate whether selected single-nucleotide polymorphisms (SNPs) in three core genes involved in the metabolism and transport of sunitinib and the mTOR inhibitors everolimus and temsirolimus are associated with adverse events (AEs).

DESIGN, SETTING, AND PARTICIPANTS

Germline DNA was extracted from blood or normal kidney tissue from mRCC patients of Caucasian ethnicity in two cohorts treated with either sunitinib (n=159) or mTOR inhibitors (n=62). Six SNPs in three candidate genes (CYP3A4: rs2242480, rs4646437, and rs2246709; CYP3A5: rs15524; and ABCB1: rs2032582 and rs1045642) were analyzed.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Primary endpoints were grade ≥3 AEs for all patients; grade ≥3 hypertension in the sunitinib cohort, and any grade pneumonitis in the mTOR inhibitors cohort. A logistic regression model was used to assess the association between SNPs and AEs, with adjustment for relevant clinical factors.

RESULTS AND LIMITATIONS

In total, 221 samples were successfully genotyped for the selected SNPs. In the sunitinib cohort, the CYP3A4 rs464637 AG variant was associated with a lower risk of high-grade AEs (odds ratio 0.27, 95% confidence interval 0.08-0.88; p=0.03), but no SNPs were associated with hypertension. In the mTOR inhibitor cohort, none of the selected SNPs was associated with analyzed toxicities.

CONCLUSIONS

We observed an association between CYP3A4 polymorphisms and toxicity outcomes in mRCC patients treated with sunitinib, but not with everolimus or temsirolimus. Our findings are exploratory in nature, and further validation in independent and larger cohorts is needed.

PATIENT SUMMARY

We found that variants of CYP3A4, a gene involved in drug metabolism, are associated with sunitinib toxicity. This information may help in better selection of patients for targeted therapies in metastatic renal cell carcinoma.

New systemic therapies for locally advanced and metastatic thyroid cancer

Thyroid cancer affects one in 100 people over their lifetime. Differentiated and medullary thyroid cancer, refractory to traditional therapy, respond poorly to chemotherapeutic agents. However, tyrosine kinase inhibitors provide new hope for stabilizing disease in patients with advanced progressive disease. There are multiple tyrosine kinase inhibitors under study for thyroid cancer and currently four drugs that are US FDA approved. Nonetheless, use of these drugs should be selective given a significant adverse event profile and diseases with a typically indolent course. This review will cover molecular mechanisms in thyroid cancer as they are relevant to targeted therapies and review available evidence for the safety and efficacy of therapies currently approved and under study for thyroid cancer.

Mechanisms of Vascular Smooth Muscle Contraction and the Basis for Pharmacologic Treatment of Smooth Muscle Disorders

The smooth muscle cell directly drives the contraction of the vascular wall and hence regulates the size of the blood vessel lumen. We review here the current understanding of the molecular mechanisms by which agonists, therapeutics, and diseases regulate contractility of the vascular smooth muscle cell and we place this within the context of whole body function. We also discuss the implications for personalized medicine and highlight specific potential target molecules that may provide opportunities for the future development of new therapeutics to regulate vascular function.

Safety and tolerability of sorafenib in patients with radioiodine-refractory thyroid cancer

Effective adverse event (AE) management is critical to maintaining patients on anticancer therapies. The DECISION trial was a multicenter, randomized, double-blind, placebo-controlled, Phase 3 trial which investigated sorafenib for treatment of progressive, advanced, or metastatic radioactive iodine-refractory, differentiated thyroid carcinoma. Four hundred and seventeen adult patients were randomized (1:1) to receive oral sorafenib (400 mg, twice daily) or placebo, until progression, unacceptable toxicity, noncompliance, or withdrawal. Progression-free survival, the primary endpoint of DECISION, was reported previously. To elucidate the patterns and management of AEs in sorafenib-treated patients in the DECISION trial, this report describes detailed, by-treatment-cycle analyses of the incidence, prevalence, and severity of hand-foot skin reaction (HFSR), rash/desquamation, hypertension, diarrhea, fatigue, weight loss, increased serum thyroid stimulating hormone, and hypocalcemia, as well as the interventions used to manage these AEs. By-cycle incidence of the above-selected AEs with sorafenib was generally highest in cycle 1 or 2 then decreased. AE prevalence generally increased over cycles 2-6 then stabilized or declined. Among these AEs, only weight loss tended to increase in severity (from grade 1 to 2) over time; severity of HFSR and rash/desquamation declined over time. AEs were mostly grade 1 or 2, and were generally managed with dose interruptions/reductions, and concomitant medications (e.g. antidiarrheals, antihypertensives, dermatologic preparations). Most dose interruptions/reductions occurred in early cycles. In conclusion, AEs with sorafenib in DECISION were typically grade 1 or 2, occurred early during the treatment course, and were manageable over time.

Response to sorafenib treatment in advanced metastatic thyroid cancer

OBJECTIVE

To investigate the efficacy of sorafenib in progressive radioiodine resistant metastatic thyroid carcinoma.

SUBJECTS AND METHODS

Off-label observational study. Sorafenib 400 mg twice daily was evaluated. Therapy duration was 12 ± 3 months (range 6-16 months).

RESULTS

Eight patients were included (seven papillary, one insular variant). The eight patients meeting study criteria received sorafenib 400 mg orally twice a day until disease progression or unacceptable toxicity developed. One patient showed a partial response with tumor regression of -35%, six months after the beginning of the treatment; five patients exhibited stable disease and two patients had progressive disease and died. Thyroglobulin decreased within 4 weeks in all patients by 50% ± 23%. Adverse events: one patient had heart failure, and recovered after sorafenib withdrawal. However, she died five months later of sudden death.

CONCLUSION

These data suggest a possible role for sorafenib in the treatment of progressive metastatic DTC. Adverse event are usually manageable, but severe ones may appear and these patients should be strictly controlled.

Lenvatinib versus placebo in radioiodine-refractory thyroid cancer

BACKGROUND

Lenvatinib, an oral inhibitor of vascular endothelial growth factor receptors 1, 2, and 3, fibroblast growth factor receptors 1 through 4, platelet-derived growth factor receptor α, RET, and KIT, showed clinical activity in a phase 2 study involving patients with differentiated thyroid cancer that was refractory to radioiodine (iodine-131).

METHODS

In our phase 3, randomized, double-blind, multicenter study involving patients with progressive thyroid cancer that was refractory to iodine-131, we randomly assigned 261 patients to receive lenvatinib (at a daily dose of 24 mg per day in 28-day cycles) and 131 patients to receive placebo. At the time of disease progression, patients in the placebo group could receive open-label lenvatinib. The primary end point was progression-free survival. Secondary end points included the response rate, overall survival, and safety.

RESULTS

The median progression-free survival was 18.3 months in the lenvatinib group and 3.6 months in the placebo group (hazard ratio for progression or death, 0.21; 99% confidence interval, 0.14 to 0.31; P<0.001). A progression-free survival benefit associated with lenvatinib was observed in all prespecified subgroups. The response rate was 64.8% in the lenvatinib group (4 complete responses and 165 partial responses) and 1.5% in the placebo group (P<0.001). The median overall survival was not reached in either group. Treatment-related adverse effects of any grade, which occurred in more than 40% of patients in the lenvatinib group, were hypertension (in 67.8% of the patients), diarrhea (in 59.4%), fatigue or asthenia (in 59.0%), decreased appetite (in 50.2%), decreased weight (in 46.4%), and nausea (in 41.0%). Discontinuations of the study drug because of adverse effects occurred in 37 patients who received lenvatinib (14.2%) and 3 patients who received placebo (2.3%). In the lenvatinib group, 6 of 20 deaths that occurred during the treatment period were considered to be drug-related.

CONCLUSIONS

Lenvatinib, as compared with placebo, was associated with significant improvements in progression-free survival and the response rate among patients with iodine-131-refractory thyroid cancer. Patients who received lenvatinib had more adverse effects. (Funded by Eisai; SELECT ClinicalTrials.gov number, NCT01321554.).

Multikinase inhibitors use in differentiated thyroid carcinoma

Thyroid cancer is the most common endocrine malignancy, and its incidence is increasing. Standard therapy for most patients with localized differentiated thyroid cancer (DTC) includes surgery, radioactive iodine, and thyroid hormone replacement. A minority of thyroid cancer patients requires systemic therapy for metastatic disease. Patients with metastatic DTC do not usually benefit from traditional cytotoxic chemotherapy. In this review, we describe newly developed small-molecule tyrosine kinase inhibitors (TKIs) that are being actively tested and used in the management of advanced thyroid cancer. The use of TKIs as a form of molecular targeted therapy is evolving based on understanding of the pathways involved in DTC. Disrupting tumor vascular supply by targeting vascular endothelial growth factor receptor signaling is the most commonly used approach to treat advanced/metastatic DTC. Other mechanisms include targeting BRAF, MAPK/ERK kinase, or mammalian target of rapamycin signaling. Although TKIs appear to have superior efficacy compared to cytotoxic chemotherapy, they can cause substantial adverse effects; symptomatic management of adverse effects, dose adjustment, or cessation of therapy may be required.

A phase I study of cabozantinib (XL184) in patients with differentiated thyroid cancer

BACKGROUND

Cabozantinib targets tyrosine kinases including MET, vascular endothelial growth factor (VEGF) receptor 2, and rearranged during transfection (RET). Differentiated thyroid cancer (DTC) is a tumor type that may be sensitive to cabozantinib. Therefore, we evaluated cabozantinib in a cohort of heavily pretreated patients with metastatic DTC.

METHODS

This single-arm open-label phase I trial assessed the safety, tolerability, and antitumor activity of cabozantinib in DTC patients taking part in a drug-drug interaction study. Adult patients with histologically confirmed metastatic or surgically unresectable DTC (including papillary, follicular, or Hürthle cell) were enrolled. Patients received daily oral dosing of 140 mg cabozantinib. Safety was assessed by evaluation of adverse events (AEs), vital signs, electrocardiograms, laboratory tests, and concomitant medications. Tumor response by magnetic resonance imaging or computed tomography scan was investigator assessed using Response Evaluation Criteria In Solid Tumors (RECIST) v1.0.

RESULTS

The study enrolled 15 patients who had failed standard radioactive iodine therapy. Patients had received a median of two prior systemic agents, and 11 patients (73%) had previously received at least one VEGF pathway inhibiting therapy. Common AEs included diarrhea, nausea, fatigue, and decreased appetite. Partial response was reported in eight patients (53%). Median progression-free survival and median overall survival were not reached.

CONCLUSIONS

Cabozantinib demonstrates a safety profile similar to other multitargeted VEGFR inhibitors in advanced DTC patients. The antitumor activity observed in this study warrants further investigation of cabozantinib in patients with advanced DTC.

Sorafenib and thyroid cancer

Sorafenib (Nexavar) is a multikinase inhibitor, which has demonstrated both anti-proliferative and anti-angiogenic properties in vitro and in vivo, inhibiting the activity of targets present in the tumor cell [c-RAF (proto-oncogene serine/threonine-protein kinase), BRAF, (V600E)BRAF, c-KIT, and FMS-like tyrosine kinase 3] and in tumor vessels (c-RAF, vascular endothelial growth factor receptor-2, vascular endothelial growth factor receptor-3, and platelet-derived growth factor receptor β). For several years, sorafenib has been approved for the treatment of hepatocellular carcinoma and advanced renal cell carcinoma. After previous studies showing that sorafenib was able to inhibit oncogenic RET mutants, (V600E)BRAF, and angiogenesis and growth of orthotopic anaplastic thyroid cancer xenografts in nude mice, some clinical trials demonstrated the effectiveness of sorafenib in advanced thyroid cancer. Currently, the evaluation of the clinical safety and efficacy of sorafenib for the treatment of advanced thyroid cancer is ongoing. This article reviews the anti-neoplastic effect of sorafenib in thyroid cancer. Several completed (or ongoing) studies have evaluated the long-term efficacy and tolerability of sorafenib in patients with papillary and medullary aggressive thyroid cancer. The results suggest that sorafenib is a promising therapeutic option in patients with advanced thyroid cancer that is not responsive to traditional therapeutic strategies.

Treating medullary thyroid cancer in the age of targeted therapy

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor deriving from the thyroid parafollicular cell. Thyroidectomy continues to serve as the primary initial treatment for this cancer. Because standard cytotoxic chemotherapy has proven ineffective, reoperation and external beam radiation therapy had been the only tools to treat recurrences or distant disease. The discovery that aberrant activation of RET, a receptor tyrosine kinase, is a primary driver of MTC tumorigenesis led to clinical trials using RET-targeting tyrosine kinase inhibitors. The successes of those trials led to the approval of vandetanib and cabozantinib for treating patients with progressive or symptomatic MTC. The availability of these drugs, along with additional targeted therapies in development, requires a thoughtful reconsideration of the approach to treating patients with unresectable locally advanced and/or metastatic progressive MTC.

Targeted therapy with kinase inhibitors in aggressive endocrine tumors

INTRODUCTION

Kinase inhibitors (KIs) are a class of anticancer drugs that inhibit activity of the enzymes protein kinases, which regulate crucial cellular processes and have a demonstrated role in human oncogenesis. Treatment of advanced forms of endocrine cancer which are not responsive to cytotoxic chemotherapies is challenging and use of KIs is gaining a growing role in this field.

AREAS COVERED

The authors summarize the main genetic alterations known to be linked to endocrine tumors, indicating the rationale for utilizing KIs. Furthermore, they present an updated analysis of clinical trials available on PubMed Central, which were pertinent to the activities of KIs in aggressive endocrine cancer. The authors also discuss the adverse effects of KIs and summarize likely involved underlying mechanisms.

EXPERT OPINION

KIs are effective in obtaining a radiological disease control and an improvement of progression-free survival in several forms of endocrine cancer but will never deliver a knockout blow of the disease, due to mechanisms of adaptation to circumvent the specific molecular blockade. The new frontier of KIs treatment is to identify agents that could synergize activity of KIs. The true goal will be to perform an overall genotyping of each tumor, thus predicting the impact of combined targeted therapies in the context of a particular constellation of mutant genes.

Localization of CaSR antagonists in CaSR-expressing medullary thyroid cancer

OBJECTIVE

Image-based localization of medullary thyroid cancer (MTC) and parathyroid glands would improve the surgical outcomes of these diseases. MTC and parathyroid glands express high levels of calcium-sensing receptor (CaSR). The aim of this study was to prove the concept that CaSR antagonists specifically localize to CaSR-expressing tumors in vivo.

DESIGN

We synthesized two isomers of a known CaSR calcilytic, Calhex 231, and four new analogs, which have a favorable structure for labeling. Their antagonistic activity was determined using immunoblots demonstrating decreased ERK1/2 phosphorylation after calcium stimulation in human embryonic kidney cells overexpressing CaSR. Compound 9 was further radiolabeled with (125)I and evaluated in nude mice with and without heterotransplanted xenografts of MTC cell lines, TT and MZ-CRC-1, that do and do not express CaSR, respectively.

RESULTS

Two newly synthesized compounds, 9 and 11, exhibited better antagonistic activity than Calhex 231. The half-life of (125)I-compound 9 in nude mice without xenografts was 9.9 hours. A biodistribution study in nude mice bearing both tumors demonstrated that the uptake of radioactivity in TT tumors was higher than in MZ-CRC-1 tumors at 24 hours: 0.39 ± 0.24 vs 0.18 ± 0.12 percentage of injected dose per gram of tissue (%ID/g) (P = .002), with a ratio of 2.25 ± 0.62. Tumor-to-background ratios for TT tumors, but not MZ-CRC-1 tumors, increased with time. Tumor-to-blood values increased from 2.02 ± 0.52 at 1 hour to 3.29 ± 0.98 at 24 hour (P = .015) for TT tumors, and 1.7 ± 0.56 at 1 hour to 1.48 ± 0.33 at 24 hour (P = .36) for MZ-CRC-1 tumors.

CONCLUSIONS

Our new CaSR antagonists specifically inhibit CaSR function in vitro, preferentially localize to CaSR-expressing tumors in vivo, and therefore have the potential to serve as scaffolds for further development as imaging pharmaceuticals.

Clinical efficacy of targeted biologic agents as second-line therapy of advanced thyroid cancer

Targeted biologic agents showed clinically meaningful efficacy as front-line therapy for advanced radioiodine-refractory and medullary thyroid cancer. The clinical benefit of these agents beyond the front line has yet to be established.

METHODS

We assessed the clinical benefit of targeted agents in patients with advanced differentiated and medullary thyroid cancer treated at a single academic cancer center. We determined efficacy and compared front-line and second-line benefit using biochemical and anatomic response, time to treatment failure, and progression-free survival (PFS). Statistical differences were assessed by t test and chi-square test. Survival curves were generated by the Kaplan-Meier method. Differences in survival were assessed using the log-rank test, and a p value <.05 was considered significant.

RESULTS

We identified 39 patients with advanced differentiated and medullary thyroid cancer treated with targeted biologic agents. Median age was 56.3 years. Overall, 25 men and 14 women participated. Histology showed 23% medullary and 77% differentiated cancer. Nineteen patients progressed on front-line therapy and subsequently received second-line therapy. Targeted agents conferred clinically meaningful benefit in the second-line setting in terms of biochemical response (13.3%), clinical benefit (83.3%), median time to treatment failure (4.0 months; 95% confidence interval: 2.6-8.2), and median PFS (4.6 months; 95% confidence interval: 3.2-8.2). Second-line benefit (median PFS) was more modest in comparison to the front-line setting in both genders (women: 3 months vs. 12.2 months; men: 6 months vs. 19.7 months), in differentiated cancers (4.1 months vs. 15.7 months), and with vascular targeting agents (4.4 months vs. 20.1 months).

CONCLUSION

Patients with advanced thyroid cancer derived meaningful clinical benefit from additional therapy with a biologic agent following disease progression on front-line targeted therapy.

Sorafenib in metastatic radioactive iodine-refractory differentiated thyroid cancer: A pilot study

The incidence and mortality of thyroid cancer are on the increase worldwide and the treatment options for progressive, radioactive iodine (RAI)-refractory metastatic differentiated thyroid cancer (DTC) patients are currently limited. Sorafenib is a multikinase inhibitor that targets several molecular signals, which are believed to be involved in the pathogenesis of DTC. In this study, we reported our experience with the off-label use of sorafenib in Chinese cancer patients. A total of 8 patients (7 with papillary and 1 with follicular thyroid cancer) were recruited in this study. The partial response (PR) rate was 50.0% and 5 of the 8 patients (62.5%) achieved a durable response. The median progression-free survival (PFS) and overall survival (OS) were 40.1 and 55.0 weeks, respectively. Lung metastases were more sensitive to sorafenib compared to lymph nodes. The tumor marker response was not in accordance with the radiological response, although patients with tumor marker complete response (CR) exhibited a longer PFS and OS compared to those without a CR. Common adverse events (AEs) included palmar-plantar erythrodysesthesia, hypertension, diarrhea, weight loss and alopecia. Grade 4 AEs comprised hypocalcemia (1 patient) and elevated amylase levels (1 patient). A dose reduction was required in 62.5% of the patients. In conclusion, sorafenib exhibited a clinically relevant antitumor activity in patients with progressive metastatic RAI-refractory DTC, although the majority of the patients required a dose reduction due to intolerable toxicity.

Evolving approaches to patients with advanced differentiated thyroid cancer

Advanced differentiated thyroid cancer (DTC), defined by clinical characteristics including gross extrathyroidal invasion, distant metastases, radioiodine (RAI) resistance, and avidity for 18-fluorodeoxyglucose (positron emission tomography-positive), is found in approximately 10-20% of patients with DTC. Standard therapy (surgery, RAI, TSH suppression with levothyroxine) is ineffective for many of these patients, as is standard chemotherapy. Our understanding of the molecular mechanisms leading to DTC and the transformation to advanced DTC has rapidly evolved over the past 15-20 years. Newer targeted therapy, specifically inhibitors of intracellular kinase signaling pathways, and cooperative multicenter clinical trials have dramatically changed the therapeutic landscape for patients with advanced DTC. In this review focusing on morbidities, molecules, and medicinals, we present a patient with advanced DTC, explore the genetics and molecular biology of advanced DTC, and review evolving therapies for these patients including multikinase inhibitors, selective kinase inhibitors, and combination therapies.

Sorafenib in advanced iodine-refractory differentiated thyroid cancer: efficacy, safety and exploratory analysis of role of serum thyroglobulin and FDG-PET

CONTEXT

Radioactive iodine is a crucial tool for treatment of differentiated thyroid cancer (DTC). In 5% of cases, DTCs lose I-131 avidity and assume an aggressive behaviour. Treatment options for iodine-refractory DTC are limited. We report the experience of off-label use of the tyrosine kinase inhibitor sorafenib for treatment of advanced iodine-refractory DTC.

DESIGN

Patients with progressive DTC refractory to radioactive iodine were treated with sorafenib used off-label independently from their performance status. Primary study end-points were radiological response, progression-free survival (PFS) and safety. Secondary end-points were site-specific radiological response and overall survival (OS). An exploratory analysis of the role of serum thyroglobulin (Tg) and fluorodeoxyglucose (FDG) positron emission tomography (PET) was performed.

RESULTS

A total of 17 patients were included in the study. Median follow-up was 15·5 months. Clinical benefit was obtained in 71% of subjects (30% partial response and 41% stable disease). Sorafenib was mostly well tolerated, but a high incidence of fatal events was reported (three patients died from severe bleeding events and two from cardiac arrest). Median PFS was 9 months. Median OS was 10 months. The best responses were observed in lymph nodes and lung. Baseline Tg levels and the Tg response to treatment were correlated to both radiological response and PFS. Baseline FDG-PET assessment and early FDG-PET response were correlated to radiological response.

CONCLUSIONS

Sorafenib allows morphological disease control in the majority of patients with iodine-refractory DTC. Progression-free survival and overall survival were lower than in previous studies as a consequence of the worse clinical condition of our patients. Sorafenib is mostly well tolerated but could have been responsible for the reported fatal events. Baseline Tg and the Tg response to treatment could be useful for predicting morphological response and clinical outcome. Early FDG-PET response could be helpful for the timely identification of nonresponding patients.

The Use of Sorafenib in the Thyroid Cancer

There are not effective therapies for metastatic unresectable, non-RAI-avid thyroid carcinomas. Fortunately, thyroid carcinomas represent a promising paradigm for targeted therapy due to the presence of activing mutations of genes coding the kinase tyrosines which are involved in all functions of cancer cells (such as: growth or invasion). In this paper an efficacy and toxicity of sorafenib, one of the multi-kinase inhibitors in thyroid carcinomas treatment is presented.

The noninvestigational use of tyrosine kinase inhibitors in thyroid cancer: establishing a standard for patient safety and monitoring

CONTEXT

The increasing use of tyrosine kinase inhibitor therapy outside of the context of the clinical trial for treatment of advanced thyroid cancer has highlighted the need for a systematic approach to the clinical application of these agents in order to improve patient safety and monitoring promote consistency among providers, and ensure compliance with both institutional and industry standards.

EVIDENCE

We reviewed professional thyroid cancer guidelines, the National Comprehensive Cancer Network task force reports, American Society of Clinical Oncology safety standards, review articles, and clinical trials published within the past 10 yr and also included relevant older studies.

CONCLUSIONS

Review of available published data and the collective experience prescribing tyrosine kinase inhibitors at The University of Texas MD Anderson Cancer Center have highlighted the need for a systematic, comprehensive, and uniform approach to managing these patients. This paper discusses the approach adopted by the Department of Endocrine Neoplasia at the MD Anderson Cancer Center and illustrates practice patterns, experience, and our standardized approach related to prescribing commercially available tyrosine kinase inhibitors outside of the context of a clinical trial for patients with advanced thyroid cancer.

Optimizing therapy for radioactive iodine-refractory differentiated thyroid cancer: current state of the art and future directions

The majority of patients with differentiated thyroid cancer are cured with standard primary treatments including surgery, radioactive iodine and TSH suppression. A small proportion of patients who develop radioactive iodine-refractory metastatic disease have few treatment options. Recent discovery of the molecular mechanisms that contribute to thyroid cancer tumorigenesis and its progression have revealed key targets that are currently being evaluated in clinical trials. In the last decade several novel targeted therapies have shown encouraging results and have brought hope to patients with advanced disease. However, identifying the subpopulation of patients who may benefit from systemic therapies remains a challenge as the use of these therapeutic modalities is associated with high toxicity rates and most patients have a long indolent phase where the tumor is stable or slowly progressive and asymptomatic. The objective of this review is to summarize the management of patients with metastatic, radioactive iodine refractory differentiated thyroid cancer.

Role of vandetanib in the management of medullary thyroid cancer

Traditionally available treatments, like cytotoxic chemotherapy and external-beam radiation therapy, are limited and essentially ineffective for metastatic medullary thyroid carcinoma (MTC). In the last decade, small-molecule tyrosine kinase inhibitors (TKI) have been introduced in the field of thyroid cancer, after having been shown effective in a wide variety of other tumors. This review focuses on vandetanib (ZD6474, Zactima™; AstraZeneca) and its role in the treatment of MTC. Vandetanib is an oral TKI that targets VEGF receptors 2 and 3, RET, and at higher concentrations, the epidermal growth factor (EGF) receptor. This drug has been tested in two important phase II studies which demonstrated that both the 100 and 300 mg/day dosage of vandetanib have antitumor activity on advanced MTC. A phase III trial (ZETA trial) evaluating vandetanib in 331 patients with locally advanced or metastatic MTC showed a significant prolongation of PFS for patients receiving vandetanib compared with placebo. Toxicity surveillance in all studies reported high rates of adverse effects with diarrhea, rash, fatigue and nausea being the most commonly experienced by patients. Vandetanib is currently approved in the United States for unresectable locally advanced or metastatic MTC and has become a new standard of care in this rare and indolent pathology.

Differentiated thyroid cancer: management of patients with radioiodine nonresponsive disease

Differentiated thyroid carcinoma (papillary and follicular) has a favorable prognosis with an 85% 10-year survival. The patients that recur often require surgery and further radioactive iodine to render them disease-free. Five percent of thyroid cancer patients, however, will eventually succumb to their disease. Metastatic thyroid cancer is treated with radioactive iodine if the metastases are radioiodine avid. Cytotoxic chemotherapies for advanced or metastatic noniodine avid thyroid cancers show no prolonged responses and in general have fallen out of favor. Novel targeted therapies have recently been discovered that have given rise to clinical trials for thyroid cancer. Newer aberrations in molecular pathways and oncogenic mutations in thyroid cancer together with the role of angiogenesis in tumor growth have been central to these discoveries. This paper will focus on the management and treatment of metastatic differentiated thyroid cancers that do not take up radioactive iodine.