Efficacy and tolerability of different starting doses of sorafenib in patients with differentiated thyroid cancer

Tribbles Pseudokinase 3 Converts Sorafenib Therapy to Neutrophil-Mediated Lung Metastasis in Hepatocellular Carcinoma

Rapid development of resistance to sorafenib and subsequent hyperprogression in patients with advanced hepatocellular carcinoma (HCC) pose significant challenges, with the underlying mechanisms still largely unknown. Herein, sorafenib-induced TRIB3 is identified as a liver-specific determinant driving secondary resistance to sorafenib by facilitating the accumulation of protumorigenic neutrophils within tumors. Mechanistically, TRIB3, triggered by the sorafenib-elicited ROS-ER stress axis, operates in an NF-κB-dependent manner to upregulate CXCR1/2 ligands, subsequently promoting neutrophil recruitment into tumors. These enriched neutrophils enhance epithelial-mesenchymal transition processes in malignant cells through the oncostatin M-STAT3 pathway, thereby repurposing the therapeutic efficacy of sorafenib away from anti-angiogenesis and toward lung metastasis. Clinically, elevated TRIB3 expression indicates inferior survival and unfavorable clinical efficacy of sorafenib in HCC patients. Correspondingly, strategies that either inhibiting TRIB3 upregulation or blocking its downstream signaling successfully augment the therapeutic efficacy of sorafenib and prevent sorafenib-induced hyperprogression in vivo. The study thus identifies a pivotal mechanism of sorafenib resistance in HCC, centered on the TRIB3-mediated recruitment of protumorigenic neutrophils and subsequent disease hyperprogression.

New approaches for patients with advanced radioiodine-refractory thyroid cancer

The cumulative evidence over the past decades has shown that the incidence of differentiated thyroid carcinoma (DTC) has exponentially increased. Approximately 10% of patients with DTC exhibit recurrent or metastatic disease, and about two-thirds of the latter will be defined as refractory to radioactive iodine (RAIR) treatment. Since this condition implies 10-year survival rates less than 10% after detection, using available treatments, such as systemic and targeted therapies, have become increasingly relevant. The initiation of these treatments aims to reach stabilization, tumor volume reduction, and/or symptom improvement and it should be decided by highly specialized endocrinologists/oncologists on the basis of patient's features. Considering that despite enlarged progression-free survival was proven, multikinase inhibitors remain non-curative, their benefits last for a limited time and the side effects potentially cause harm and quality of life reduction. In this context, molecular testing of cancer cells provides a promising spectrum of targeted therapies that offer increased compatibility with individual patient needs by improving efficacy, progression free survival, overall survival and adverse events profile. This review article aims to provide a summary of the current therapeutic strategies in advanced RAIR-DTC, including approved target therapies as well as those for off-label use, RAI resensitization agents, and immunotherapy.

Exposure-toxicity relationship of cabozantinib in patients with renal cell cancer and salivary gland cancer

Cabozantinib is registered in fixed 60 mg dose. However, 46% to 62% of patients in the registration studies needed a dose reduction due to toxicity. Improved clinical efficacy has been observed in renal cell carcinoma patients (RCC) with a cabozantinib exposure greater than 750 μg/L. In our study we explored the cabozantinib exposure in patients with different tumour types. We included RCC patients from routine care and salivary gland carcinoma (SGC) patients from a phase II study with ≥1 measured C_min at steady‐state. The geometric mean (GM) C_min at the starting dose, at 40 mg and at best tolerated dose (BTD) were compared between both tumour types. Forty‐seven patients were included. All SGC patients (n = 22) started with 60 mg, while 52% of RCC patients started with 40 mg. GM C_min at the start dose was 1456 μg/L (95% CI: 1185‐1789) vs 682 μg/L (95% CI: 572‐812) (P < .001) for SGC and RCC patients, respectively. When dose‐normalised to 40 mg, SGC patients had a significantly higher cabozantinib exposure compared to RCC patients (C_min 971 μg/L [95% CI: 790‐1193] vs 669 μg/L [95% CI: 568‐788]) (P = .005). Dose reductions due to toxicity were needed in 91% and 60% of SGC and RCC patients, respectively. Median BTD was between 20 to 30 mg for SGC and 40 mg for RCC patients. GM C_min at BTD were comparable between the SGC and the RCC group, 694 μg/L (95% CI: 584‐824) vs 583 μg/L (95% CI: 496‐671) (P = .1). The observed cabozantinib exposure at BTD of approximately 600 μg/L is below the previously proposed target. Surprisingly, a comparable exposure at BTD was reached at different dosages of cabozantinib for SGC patients compared to RCC patients Further research is warranted to identify the optimal exposure and starting dose to balance efficacy and toxicity.

What's new?

Cabozantinib, a potent tyrosine kinase inhibitor that targets multiple signaling pathways, is approved for use against advanced renal cell carcinoma (RCC). Variations in cabozantinib clearance, however, warrant further investigation. Here, the authors evaluated cabozantinib exposure in RCC patients and in patients with salivary gland cancer (SGC). SGC patients were found to have significantly higher cabozantinib exposure compared to RCC patients following a 40 mg dose. However, the best‐tolerated cabozantinib exposure was equivalent (~600 μg/L) for both tumor types and was substantially below the previously proposed target. The findings offer insight on exposure, dose, and the balance between efficacy and toxicity for cabozantinib.

Questions and Controversies in the Clinical Application of Tyrosine Kinase Inhibitors to Treat Patients with Radioiodine-Refractory Differentiated Thyroid Carcinoma: Expert Perspectives

Notwithstanding regulatory approval of lenvatinib and sorafenib to treat radioiodine-refractory differentiated thyroid carcinoma (RAI-R DTC), important questions and controversies persist regarding this use of these tyrosine kinase inhibitors (TKIs). RAI-R DTC experts from German tertiary referral centers convened to identify and explore such issues; this paper summarizes their discussions. One challenge is determining when to start TKI therapy. Decision-making should be shared between patients and multidisciplinary caregivers, and should consider tumor size/burden, growth rate, and site(s), the key drivers of RAI-R DTC morbidity and mortality, along with current and projected tumor-related symptomatology, co-morbidities, and performance status. Another question involves choice of first-line TKIs. Currently, lenvatinib is generally preferred, due to greater increase in progression-free survival versus placebo treatment and higher response rate in its pivotal trial versus that of sorafenib; additionally, in those studies, lenvatinib but not sorafenib showed overall survival benefit in subgroup analysis. Whether recommended maximum or lower TKI starting doses better balance anti-tumor effects versus tolerability is also unresolved. Exploratory analyses of lenvatinib pivotal study data suggest dose-response effects, possibly favoring higher dosing; however, results are awaited of a prospective comparison of lenvatinib starting regimens. Some controversy surrounds determination of net therapeutic benefit, the key criterion for continuing TKI therapy: if tolerability is acceptable, overall disease control may justify further treatment despite limited but manageable progression. Future research should assess potential guideposts for starting TKIs; fine-tune dosing strategies and further characterize antitumor efficacy; and evaluate interventions to prevent and/or treat TKI toxicity, particularly palmar-plantar erythrodysesthesia and fatigue.

Transforming approaches to treating TRK fusion cancer: historical comparison of larotrectinib and histology-specific therapies

OBJECTIVE

The results from basket trials utilized to gain regulatory approval of tumor-agnostic therapies can be difficult to interpret without the context of a comparator arm. We describe the role and efficacy of histology-based treatments to provide a historical comparison with larotrectinib.

METHODS

A systematic literature review (SLR) was conducted on the clinical outcomes of current histology-based standard of care treatments used in non-small cell lung cancer, colorectal cancer, thyroid cancer, gliomas, soft tissue sarcoma, salivary gland cancer, and infantile fibrosarcoma (7 of the 21 tumor histologies in the larotrectinib trials). The review focused on advanced stage/metastatic disease to make a historical comparison with larotrectinib.

RESULTS

Larotrectinib provides positive outcomes in both adult and pediatric patients with advanced or metastatic solid tumors known to harbor NTRK gene fusions across a wide range of tumor types. Although the numbers of patients per tumor type are limited, the results of this historical comparison demonstrated that larotrectinib is an efficacious treatment option when naïvely indirectly compared with historical treatments across all 7 reviewed tumor types, especially in comparison to later lines of therapy.

CONCLUSIONS

Utilizing larotrectinib as a case example across these types of historical comparisons shows that larotrectinib provides positive efficacy outcomes in TRK fusion cancer across tumor histologies known to harbor NTRK gene fusions that may be preferable to historical treatments.

Sorafenib and radioiodine-refractory differentiated thyroid cancer (RR-DTC): a systematic review and meta-analysis

BACKGROUND

Except conventional treatments, research on medical approach for radioiodine-refractory differentiated thyroid cancer (RR-DTC) was considered particularly challenging. Sorafenib, a novel biological agent, has been widely studied in the treatment of RR-DTC for years. We performed a systematic review and meta-analysis to explore the efficiency and safety of treating RR-DTC patients with sorafenib.

METHODS

An electronic search on PubMed/Medline and Embase was carried out to search associated articles. Fixed-effects or random-effects models were chose according to the heterogeneity.

RESULTS

A total of 15 eligible studies (636 patients) were included. As shown by the only randomised clinical trial-DECISION, sorafenib significantly improved progression-free survival (PFS) compared with placebo in patients with progressive RR-DTC. The pooled analysis indicated that there were 26% patients (95% CI: 0.19-0.34) achieved partial response (PR), and 44% patients (98% CI: 0.39-0.48) achieved stable disease (SD). The most frequent adverse effects (AEs) observed included hand-foot syndrome (HFS), diarrhoea, fatigue, alopecia, weight loss (WS) and rash, the incidence of all grades AEs for which were 71%, 60%, 59%, 55%, 51% and 50%, respectively. There were 68% patients (252/368), who had a dose reduction because of the drug toxicities and AEs.

CONCLUSIONS

Sorafenib could improve PFS in patients with progressive RR-DTC, comparing with placebo. Due to the resistance to conventional treatments, sorafenib is considered as a promising treatment for RR-DTC by most physicians specialised in this field. However, the use of sorafenib should be cautious due to a high incidence of AEs caused by the agent. More effective agents with less toxicities are warranted.

Tumor doubling time predicts response to sorafenib in radioactive iodine-refractory differentiated thyroid cancer

Sorafenib has emerged as an effective therapeutic option for radioactive iodine (RAI)-refractory, locally advanced or metastatic differentiated thyroid cancer (DTC). We investigated the efficacy and safety of sorafenib treatment in a real-world setting and unveil predictive markers of responsiveness to sorafenib. The treatment response, progression-free survival (PFS), overall survival, and adverse events (AEs) of sorafenib-treated RAI-refractory, locally advanced or metastatic DTC patients at three institutes were retrospectively reviewed, and their tumor doubling time was calculated by three investigators. Total eighty-five patients were treated with sorafenib, and seven patients discontinued sorafenib due to AEs before the first tumor assessment. The median PFS was 14.4 months, and the objective response rate was 10.3% in 78 patients who were able to evaluate the tumor response. Age, sex, histologic type, tumor location, RAI avidity, or the presence of FDG-PET uptake did not affect PFS. However, smaller tumor size (≤1.5 cm) of the target lesions in lung showed better PFS (hazard ratio [HR] 0.39, p = 0.01), and tumors with the shortest doubling time (≤6 months) had worse outcome (HR 2.70, p < 0.01). Because of AEs, dose reductions or drug interruptions were required in 64% of patients, and eventually, 23% of patients discontinued sorafenib permanently. The most common AE was hand-foot skin reaction (HFSR). Patients with severe HFSR showed better PFS, but there were no statistical significance (HR 0.65, p = 0.05). In conclusion, small tumor size and long doubling time of each target lesion can be a prognostic marker to predict the responsiveness to sorafenib in RAI-refractory DTC patients.

Efficacy and tolerability of initial low-dose lenvatinib to treat differentiated thyroid cancer

Some patients with differentiated thyroid cancer (DTC) may require an initial low dose (LD) of lenvatinib. However, few studies have investigated the efficacy of LD lenvatinib. We compared the efficacy and tolerability of lenvatinib at an initial LD to those of the standard initial dose of 24 mg in patients with DTC.In this cross-sectional study, records of patients with DTC treated with lenvatinib were retrospectively reviewed. Patients were divided into 2 groups based on the initial dose of lenvatinib: a full-dose (FD) group that received an initial dose of 24 mg/d and a LD group that received an initial dose of less than 24 mg/d. Categorical variables were compared with the Fisher exact test and continuous variables with Student t test. A progression-free survival (PFS) curve was constructed with the Kaplan-Meier method. A probability (P) value of < .05 was considered statistically significant.Thirty-six patients with DTC were treated with lenvatinib (30 in the FD group and 6 in the LD group). The response rates were 43% and 33% in the FD and LD groups, respectively. The median PFS duration was 696 [95% confidence interval (CI): 318-not available (NA)] days in the FD group. The median PFS of the LD group was not reached (95% CI: 124-NA) (P = .293). Treatment interruptions were required in 25 (83%) patients in the FD group and 4 (67%) in the LD group (P = .573). Dose reductions were required in 28 (93%) patients in the FD group and 4 (67%) in the LD group (P = .121). There were no significant differences in the incidences of common adverse events between the 2 groups.The LD group also required dose reduction and interruption frequently. Since these findings are only the short-term results of a limited number of cases, a large number of cases and long-term observations are needed to determine whether an initial LD is effective for patients with DTC in poor general condition.

A randomized phase II study of paclitaxel alone versus paclitaxel plus sorafenib in second- and third-line treatment of patients with HER2-negative metastatic breast cancer (PASO)

Background

We conducted an open-label, randomized, two-arm multi-center study to assess the efficacy and safety of paclitaxel versus paclitaxel + sorafenib in patients with locally advanced or metastatic HER2-negative breast cancer.

Methods

Patients were randomly assigned to receive either paclitaxel monotherapy (80 mg/m²) weekly (3 weeks on, 1 week off) plus sorafenib 400 mg orally, twice a day taken continuously throughout 28 day cycles. Sorafenib dose was gradually escalated from a starting dose of 200 mg twice a day. The primary endpoint was progression free survival (PFS).

Results

A pre-planned efficacy interim analysis was performed on the data of 60 patients, 30 patients in each treatment arm. Median PFS was estimated at 6.6 months (95% CI: 5.1 to 9.0) in patients randomized to single-agent paclitaxel (Arm A) and 5.6 months (95% CI: 3.8 to 6.5) in patients randomized to paclitaxel-sorafenib combination (Arm B) therapy. Contrary to the hypothesis, the treatment effect was statistically significant in favor of paclitaxel monotherapy (hazard ratio 1.80, 95% CI: 1.02 to 3.20; log-rank test P = 0.0409). It was decided to stop the trial early for futility. Median OS was also in favor of Arm A (20.7 months (95% CI: 16.4 to 26.7) versus 12.1 months (95% CI: 5.8 to 20.4) in Arm B. Clinical control was achieved in 28 patients (93.3%) in Arm A and in 21 patients 70.0% in Arm B. Overall response rate was met in 43.3% of patients in Arm A and in 40.0% in Arm B. Toxicities were increased in Arm B with higher rates of diarrhea, nausea, neutropenia, hand-foot skin reaction (HFSR) and anorexia, Grad 3 and 4 toxicities were rare.

Conclusions

In this pre-planned interim analysis, paclitaxel-sorafenib combination therapy was not found to be superior to paclitaxel monotherapy with regard to the primary end point, progression-free survival. The trial was therefore discontinued early. There was no indication of more favorable outcomes for combination therapy in secondary efficacy end points. As expected, the safety and toxicity profile of the combination therapy was less favorable compared to monotherapy. Overall, this trial did not demonstrate that adding sorafenib to second- or third-line paclitaxel provides any clinical benefit to patients with HER2-negative advanced or metastatic breast cancer. Cautious dosing using a sorafenib ramp up schedule might have contributed to negative results.

Trial registration

The study was registered at EudraCT (No 2009–018025-73) and retrospectively registered at Clinical trials.gov on March 17, 2011 (NCT01320111).

Advances in small molecule therapy for treating metastatic thyroid cancer

INTRODUCTION

Multi kinase inhibitors (MKIs) are new drugs, which show activity against receptors of different growth factors leading to the inhibition of tumor cells growth and proliferation. This review summarizes a 10-year experience with the use of MKIs in thyroid cancer (TC). It focuses not only on sorafenib, lenvatinib, vandetanib and cabozantinib, already approved in TC, but also presents an overview of the results of different trials with distinct MKIs so far carried out in TC. Areas covered: Published results of phase I, II and III studies and other reports evaluated the efficacy of different targeted drugs in TC. Expert opinion: Despite numerous clinical trials with distinct MKIs, only four of them unequivocally demonstrated a beneficial effect on progression free survival in radioiodine refractory differentiated or medullary TC. In contrast to other solid tumors, we are still lacking in convincing evidences of their impact on overall survival. We still do not have any strong proof fulfilling evidence-based medicine criteria, when to start MKIs and which drug to use. The questions whether we really have to wait for disease progression in patients with a large tumor burden and/or aggressive types TC or when to stop MKIs treatment remain open.

Characterization of Tumor Size Changes Over Time From the Phase 3 Study of Lenvatinib in Thyroid Cancer

CONTEXT

Lenvatinib improved the progression-free survival (PFS) and overall response rate of patients with radioiodine-refractory differentiated thyroid cancer vs placebo in the Phase 3 Study of (E7080) Lenvatinib in Differentiated Cancer of the Thyroid (SELECT).

OBJECTIVE

The objective of the study was to characterize tumor size changes with lenvatinib treatment.

DESIGN

SELECT was a phase 3, randomized, double-blind, multicenter study.

SETTING

In this clinical trial, tumor assessments of lenvatinib (n = 261) and placebo-treated (n = 131) patients were performed by independent radiological review per Response Evaluation Criteria in Solid Tumors version, 1.1 at 8-week intervals.

PATIENTS

Patients with complete or partial response were defined as responders to lenvatinib (n = 169). Of the 92 nonresponders, 76 had at least one postbaseline tumor assessment and were included in this analysis.

INTERVENTIONS

Lenvatinib (24 mg once daily) or placebo in 28-day cycles until unacceptable toxicity, disease progression, or death.

MAIN OUTCOME MEASURES

This was an exploratory analysis of key end points from SELECT, including PFS, overall response rate, and tumor reduction.

RESULTS

The median maximum percentage change in tumor size was -42.9% for patients receiving lenvatinib (responders, -51.9%; nonresponders, -20.2%). Tumor size reduction was most pronounced at first assessment (median, -24.7% at 8 wk after randomization); thereafter, the rate of change was slower but continuous (-1.3% per mo). In a multivariate model, percentage change in tumor size at the first assessment was a marginally significant positive predictor for PFS (P = .06).

CONCLUSIONS

The change in tumor size conferred by lenvatinib was characterized by two phases: an initial, rapid decline, followed by slower, continuous shrinkage.

Selective use of sorafenib in the treatment of thyroid cancer

Sorafenib is a multiple kinase inhibitor (MKI) approved for the treatment of primary advanced renal cell carcinoma and advanced primary liver cancer. It was recently approved by several health agencies around the world as the first available MKI treatment for radioactive iodine-refractory advanced and progressive differentiated thyroid cancer. Sorafenib targets C-RAF, B-RAF, VEGF receptor-1, -2, -3, PDGF receptor-β, RET, c-kit, and Flt-3. As a multifunctional inhibitor, sorafenib has the potential of inhibiting tumor growth, progression, metastasis, and angiogenesis and downregulating mechanisms that protect tumors from apoptosis and has shown to increase the progression-free survival in several Phase II trials. This led to the Phase III trial (DECISION) which showed that there was an improvement in progression-free survival of 5 months for patients on sorafenib when compared to those on placebo. Adverse events with this drug are common but usually manageable. The development of resistance after 1 or 2 years is almost a rule in most patients who showed partial response or stabilization of the disease while on sorafenib, which makes it necessary to think of a plan for subsequent therapies. These may include the use of another MKI, such as lenvatinib, the second approved MKI for advanced differentiated thyroid cancer, or include patients in clinical trials or the off-label use of other MKIs. Given sorafenib's earlier approval, most centers now have access to its prescription. The goal of this review was to improve the care of these patients by describing key aspects that all prescribers will need to master in order to optimize outcomes.

Sorafenib: a review of its use in patients with radioactive iodine-refractory, metastatic differentiated thyroid carcinoma

Sorafenib (Nexavar®) is the first tyrosine kinase inhibitor to be approved for the treatment of radioactive iodine (RAI)-refractory differentiated thyroid carcinoma (DTC). In the pivotal phase III DECISION trial in patients with RAI-refractory, locally advanced or metastatic DTC, oral sorafenib 400 mg twice daily significantly prolonged median progression-free survival (PFS) relative to placebo. The PFS benefit of sorafenib over placebo was evident in all pre-specified clinical and genetic biomarker subgroups, and neither BRAF nor RAS mutation status was predictive of sorafenib benefit for PFS. The objective response rate was significantly higher in patients receiving sorafenib than in those receiving placebo; all objective responses were partial responses. The overall survival benefit of sorafenib is as yet unclear, with no significant benefit observed at the time of primary analysis or at 9 months following the primary analysis. Overall survival was possibly confounded by the crossover of patients in the placebo group to sorafenib upon disease progression. The adverse events associated with sorafenib in the DECISION trial were consistent with the known tolerability profile of the drug, with hand-foot skin reaction, diarrhea, and alopecia reported most commonly. Most treatment-emergent adverse events were grade 1 or 2 in severity and occurred early in treatment. However, a high proportion of patients discontinued sorafenib therapy or required dose reductions or interruptions because of toxicity. Although final overall survival data are awaited, current evidence suggests that sorafenib is a promising new treatment option for patients with RAI-refractory, metastatic DTC.

Sorafenib for the treatment of thyroid cancer: an updated review

INTRODUCTION

Sorafenib (Nexavar) is an oral multi-kinase inhibitor targeting B-type Raf kinase (BRAF) (both wild type and BRAF(V600E)), VEGFR1, VEGFR2, VEGFR3, PDGFRβ and RET (also RET/PTC) influencing both differentiated thyroid cancer (DTC) cell proliferation and angiogenesis.

AREAS COVERED

Encouraging results achieved in numerous Phase II trials were confirmed in a Phase III study conducted in radioiodine-refractory DTC. Sorafenib compared to placebo significantly prolongs progression-free survival, 10.8 versus 5.8 months, respectively. However, its administration resulted mainly in disease stabilization. No complete remission was obtained in any study. Beneficial effects were also demonstrated for medullary and anaplastic thyroid cancer; however further studies fulfilling evidence based medicine criteria are necessary. Its toxicity profile is convergent with other VEGFR inhibitors. The most common treatment-related side-effects involve skin toxicity (predominantly hand-foot skin reaction, different rashes and alopecia), gastrointestinal disturbances (diarrhea, abdominal pain), constitutional adverse reactions (anorexia, weight loss, fatigue) and hypertension. Although most adverse reactions are manageable, > 50% of patients required dose reduction.

EXPERT OPINION

Sorafenib constitutes the first line treatment option in advanced, radioiodine-refractory DTC. However, there are still no data on its efficacy in patients progressed after another tyrosine kinase inhibitor. Other applications of the drug, such as use as adjuvant therapy to 131-I treatment, requires further studies.

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.

Sorafenib and thyroid cancer

The emergence of serine-threonine small molecule, multi-targeted kinase inhibitors over the past decade is greatly impacting the therapeutic armamentarium for numerous malignancies, especially thyroid carcinoma. Chief among them are a class of agents referred to as vascular endothelial growth factor signal pathway inhibitors. Sorafenib is a lead compound that has been recently approved by the US FDA for radioactive iodine-refractory differentiated thyroid cancer (DTC). Sorafenib clearly is altering the natural history of DTC. In the largest randomized Phase III study ever conducted in DTC, sorafenib significantly improved progression-free survival compared to placebo (10.8 vs 5.8 months) and had an acceptable and manageable safety profile, though commonly attributed side effects of hand-foot skin reaction, diarrhea and hypertension were more frequent than in other settings. This agent represents a new treatment option for patients with progressive radioactive iodine-refractory DTC.