Phase 3 Trial of Selpercatinib in Advanced RET-Mutant Medullary Thyroid Cancer.

BACKGROUND: Selpercatinib, a highly selective, potent RET inhibitor, has shown efficacy in advanced RET-mutant medullary thyroid cancer in a phase 1-2 trial, but its efficacy as compared with approved multikinase inhibitors is unclear. METHODS: We conducted a phase 3, randomized trial comparing selpercatinib as first-line therapy with the physician's choice of cabozantinib or vandetanib (control group). Eligible patients had progressive disease documented within 14 months before enrollment. The primary end point in the protocol-specified interim efficacy analysis was progression-free survival, assessed by blinded independent central review. Crossover to selpercatinib was permitted among patients in the control group after disease progression. Treatment failure-free survival, assessed by blinded independent central review, was a secondary, alpha-controlled end point that was to be tested only if progression-free survival was significant. Among the other secondary end points were overall response and safety. RESULTS: A total of 291 patients underwent randomization. At a median follow-up of 12 months, median progression-free survival as assessed by blinded independent central review was not reached in the selpercatinib group and was 16.8 months (95% confidence interval [CI], 12.2 to 25.1) in the control group (hazard ratio for disease progression or death, 0.28; 95% CI, 0.16 to 0.48; P<0.001). Progression-free survival at 12 months was 86.8% (95% CI, 79.8 to 91.6) in the selpercatinib group and 65.7% (95% CI, 51.9 to 76.4) in the control group. Median treatment failure-free survival as assessed by blinded independent central review was not reached in the selpercatinib group and was 13.9 months in the control group (hazard ratio for disease progression, discontinuation due to treatment-related adverse events, or death, 0.25; 95% CI, 0.15 to 0.42; P<0.001). Treatment failure-free survival at 12 months was 86.2% (95% CI, 79.1 to 91.0) in the selpercatinib group and 62.1% (95% CI, 48.9 to 72.8) in the control group. The overall response was 69.4% (95% CI, 62.4 to 75.8) in the selpercatinib group and 38.8% (95% CI, 29.1 to 49.2) in the control group. Adverse events led to a dose reduction in 38.9% of the patients in the selpercatinib group, as compared with 77.3% in the control group, and to treatment discontinuation in 4.7% and 26.8%, respectively. CONCLUSIONS: Selpercatinib treatment resulted in superior progression-free survival and treatment failure-free survival as compared with cabozantinib or vandetanib in patients with RET-mutant medullary thyroid cancer. (Funded by Loxo Oncology, a subsidiary of Eli Lilly; LIBRETTO-531 ClinicalTrials.gov number, NCT04211337.).

A Misleading Case of NTRK-Rearranged Papillary Thyroid Carcinoma.

Herein, we present a misleading case of advanced papillary thyroid carcinoma with lung, node, and pleural metastases, initially diagnosed as metastatic lung adenocarcinoma with papillary features, based on the histological and immunohistochemical analysis of a pleural biopsy. Between August 2019 and August 2020, the patient received 2 ineffective lines of systemic therapy, including a first line of chemotherapy with cisplatin and pemetrexed, and a second line of immunotherapy with atezolizumab. Comprehensive genomic profiling by next-generation sequencing on the archival pleural biopsy revealed an NTRK1-TMP3 fusion and comutation of the TERT promoter, commonly found in papillary thyroid carcinoma. After palliative partial thyroidectomy that confirmed the diagnosis of papillary thyroid carcinoma, in February 2021, the patient was enrolled in the STARTRK-2 GO40782 basket trial and received entrectinib, an oral pan-TRK inhibitor specifically targeting NTRK-rearranged tumors. After initially experiencing drug-related grade 2 anorexia, dysgeusia, and neurotoxicity and grade 3 asthenia, the dose was reduced, and an excellent and durable objective response was observed.

Effects of tyrosine kinase inhibitors on thyroid function and thyroid hormone metabolism.

The increasing knowledge of the molecular mechanisms in the cell signaling pathways of malignant cells, has recently led to the discovery of several tyrosine kinases (TKs), mainly TK receptors (TKR), which play a major role in the pathogenesis of many types of cancer. These receptors, physiologically involved in cell growth and angiogenesis, may harbor mutations or be overexpressed in malignant cells, and represent a target for anticancer therapy. Indeed, several therapeutic agents targeting specific altered pathways such as RET, BRAF, RAS, EGFR and VEGFR, have been identified. Tyrosine kinase inhibitors (TKIs) affect TK dependent oncogenic pathways by competing with ATP binding sites of the TK domain, thus blocking the activity of the enzyme, and thereby inhibiting the growth and spread of several cancers. Although the therapeutic action may be very effective, these molecules, due to their mechanism of multitargeted inhibition, may produce adverse events involving several biological systems. Both hypothyroidism and thyrotoxicosis have been reported during treatment with TKI, as well as an effect on the activity of enzymes involved in thyroid hormone metabolism. The pathogenic mechanisms leading to thyroid dysfunction and changes in serum thyroid function tests occurring in patients on TKI are reviewed and discussed in this manuscript.

Lenvatinib for the Treatment of Radioiodine-Refractory Differentiated Thyroid Cancer: Treatment Optimization for Maximum Clinical Benefit.

BACKGROUND: Lenvatinib is a multitargeted tyrosine kinase inhibitor approved for treating patients with locally recurrent or metastatic progressive radioiodine-refractory differentiated thyroid cancer (RR-DTC). In this review, we discuss recent developments in the optimization of RR-DTC treatment with lenvatinib. SUMMARY: Initiation of lenvatinib treatment before a worsening of Eastern Cooperative Oncology Group performance status and elevated neutrophil-to-lymphocyte ratio could benefit patients with progressive RR-DTC. The median duration of response with lenvatinib was inversely correlated with a smaller tumor burden, and prognosis was significantly worse in patients with a high tumor burden. An 18 mg/day starting dose of lenvatinib was not noninferior to 24 mg/day and had a comparable safety profile. Timely management of adverse events is crucial, as patients with shorter dose interruptions benefitted more from lenvatinib treatment. Caution should be exercised when initiating lenvatinib in patients who have tumor infiltration into the trachea or other organs, or certain histological subtypes of DTC, as these are risk factors for fistula formation or organ perforation. The Study of (E7080) LEnvatinib in Differentiated Cancer of the Thyroid (SELECT) eligibility criteria should be considered prior to initiating lenvatinib treatment. CONCLUSIONS: Current evidence indicates that patients benefit most from lenvatinib treatment that is initiated earlier in advanced disease when the disease burden is low. A starting dose of lenvatinib 24 mg/day, with dose modifications as required, yields better outcomes as compared to 18 mg/day. Appropriate supportive care, including timely identification of adverse events, is essential to manage toxicities associated with lenvatinib, avoid longer dose interruptions, and maximize efficacy.

LIBRETTO-531: a phase III study of selpercatinib in multikinase inhibitor-naïve RET-mutant medullary thyroid cancer.

Selpercatinib is a first-in-class, highly selective and potent, central nervous system-active RET kinase inhibitor. In the phase I/II trial, selpercatinib demonstrated clinically meaningful antitumor activity with manageable toxicity in heavily pre-treated and treatment-naive patients with RET-mutant medullary thyroid cancer (MTC). LIBRETTO-531 (NCT04211337) is a multicenter, open-label, randomized, controlled, phase III trial comparing selpercatinib to cabozantinib or vandetanib in patients with advanced/metastatic RET-mutant MTC. The primary objective is to compare progression-free survival (per RECIST 1.1) by blinded independent central review of patients with progressive, advanced, multikinase inhibitor-naive, RET-mutant MTC treated with selpercatinib versus cabozantinib or vandetanib. Key secondary objectives are to compare other efficacy outcomes (per RECIST 1.1) and tolerability of selpercatinib versus cabozantinib or vandetanib.

Selpercatinib (also known by the brand name Retevmo^®/Retsevmo^®) is a new treatment available in multiple countries for people with advanced or metastatic RET-mutant medullary thyroid cancer (MTC). Thyroid cancer starts in your thyroid gland and may spread or metastasize to other parts of the body, including lungs, bones, and occasionally the brain, which means the cancer is likely to be advanced. Advanced thyroid cancer can be driven by a gene in your body, one of which is RET. This is a summary of the LIBRETTO-531 study which compares selpercatinib, which is a strong and selective inhibitor of RET, with two approved drugs, cabozantinib and vandetanib. Patients with advanced or metastatic RET-mutant MTC who have not already received treatment with kinase inhibitors are being enrolled. This trial will evaluate how long people during and after treatment live with the disease without it getting worse. Selpercatinib may affect both healthy cells and tumor cells, which can result in side effects, which will also be evaluated in this study. This study is active and currently recruiting new patients. Clinical Trial Registration: NCT04211337 (ClinicalTrials.gov).

Limited Accuracy of Pan-Trk Immunohistochemistry Screening for NTRK Rearrangements in Follicular-Derived Thyroid Carcinoma.

Patients with advanced thyroid cancer harboring NTRK rearrangements can be treated with highly effective selective inhibitors. Immunohistochemistry (IHC) analysis, to detect Trk protein expression, represents an appealing screening strategy for NTRK rearrangements, but its efficacy has been poorly explored in thyroid cancer. The aim of this study is to investigate the diagnostic utility of Trk IHC in the identification of NTRK rearrangements. A series of 26 follicular-derived thyroid tumors, positive for NTRK rearrangements, and 28 NTRK fusion-negative controls were retrospectively analyzed by IHC using the pan-Trk monoclonal antibody (clone EPR17341) on the Ventana system. Area under the curve (AUC), sensitivity and specificity were calculated by ROC analysis. Trk expression was detected in 25 samples, including 22 out of the 26 NTRK-rearranged (84.6%) and three out of 28 NTRK-negative samples (10.7%). Four out of twenty-six NTRK-rearranged thyroid tumors were negative for Trk expression (15.4%), all carrying the ETV6/NTRK3 fusion. The AUC, sensitivity and specificity were 0.87, 0.85 and 0.89, respectively. A screening based on IHC analysis showed limited sensitivity and specificity in the identification of NTRK-rearranged tumors. Since falsely negative results could preclude the administration of effective targeted drugs, alternative detection strategies should be considered for thyroid cancer.

Multiethnic genome-wide association study of differentiated thyroid cancer in the EPITHYR consortium.

Incidence of differentiated thyroid carcinoma (DTC) varies considerably between ethnic groups, with particularly high incidence rates in Pacific Islanders. DTC is one of the cancers with the highest familial risk suggesting a major role of genetic risk factors, but only few susceptibility loci were identified so far. In order to assess the contribution of known DTC susceptibility loci and to identify new ones, we conducted a multiethnic genome-wide association study (GWAS) in individuals of European ancestry and of Oceanian ancestry from Pacific Islands. Our study included 1554 cases/1973 controls of European ancestry and 301 cases/348 controls of Oceanian ancestry from seven population-based case-control studies participating to the EPITHYR consortium. All participants were genotyped using the OncoArray-500K Beadchip (Illumina). We confirmed the association with the known DTC susceptibility loci at 2q35, 8p12, 9q22.33 and 14q13.3 in the European ancestry population and suggested two novel signals at 1p31.3 and 16q23.2, which were associated with thyroid-stimulating hormone levels in previous GWAS. We additionally replicated an association with 5p15.33 reported previously in Chinese and European populations. Except at 1p31.3, all associations were in the same direction in the population of Oceanian ancestry. We also observed that the frequencies of risk alleles at 2q35, 5p15.33 and 16q23.2 were significantly higher in Oceanians than in Europeans. However, additional GWAS and epidemiological studies in Oceanian populations are needed to fully understand the highest incidence observed in these populations.

First report of benign track seeding after robot-assisted transaxillary thyroid surgery.

BACKGROUND: Robot-assisted transaxillary thyroidectomy is a well-established remote-access thyroid procedure that has been demonstrated to be as safe and effective as its time-honored conventional clamp-and-tie counterpart. However, it has been incriminated for a set of unprecedented complications that surgeons need to be aware of and deal with appropriately. PATIENT FINDINGS: The patient is a young woman who underwent robot-assisted thyroid lobectomy for a sizeable nodule that was reported as benign after fine-needle aspiration cytology. She presented 3 years later with subcutaneous nodules along the surgical track that were found to represent seeding of benign thyroid tissue. This is the first report of benign thyroid tissue seeding after a gasless transaxillary procedure. SUMMARY: Seeding along the surgical track is a potential complication of gasless remote-access thyroid surgery, even in case of benign disease, that surgeons need to be acquainted with. CONCLUSIONS: Surgeons should be aware of the potential for benign seeding after remote-access thyroid procedures. Accordingly, adequate precautions should be taken, patients should be counseled in this regard, and alternative medical strategies to control local seeding of thyroid tissue could be suggested.

A Narrative Review of Genetic Alterations in Primary Thyroid Epithelial Cancer.

Thyroid carcinoma is the most frequent endocrine neoplasia. Different types of thyroid carcinoma are described: well-differentiated papillary thyroid carcinoma (PTC), poorly differentiated thyroid carcinoma (PDTC), follicular thyroid carcinoma (FTC), anaplastic thyroid carcinoma (ATC), and medullary thyroid carcinoma (MTC). MTC is inherited as an autosomal dominant trait in 25% of cases. The genetic landscape of thyroid carcinoma has been largely deciphered. In PTC, genetic alterations have been found in about 95% of tumors: BRAF mutations and RET rearrangements are the main genetic alterations. BRAF and RAS mutations have been confirmed to play an important role also in PDTC and ATC, together with TP53 mutations that are fundamental in tumor progression. It has also been clearly demonstrated that telomerase reverse transcriptase (TERT) promoter mutations and TP53 mutations are present with a high-frequency in more advanced tumors, frequently associated with other mutations, and their presence, especially if simultaneous, is a signature of aggressiveness. In MTC, next-generation sequencing confirmed that mutations in the RET gene are the most common molecular events followed by H-RAS and K-RAS mutations. The comprehensive knowledge of the genetic events responsible for thyroid tumorigenesis is important to better predict the biological behavior and better plan the therapeutic strategy for specific treatment of the malignancy based on its molecular profile.

Thyroid Cancers: From Surgery to Current and Future Systemic Therapies through Their Molecular Identities.

Differentiated thyroid cancers (DTC) are commonly and successfully treated with total thyroidectomy plus/minus radioiodine therapy (RAI). Medullary thyroid cancer (MTC) is only treated with surgery but only intrathyroidal tumors are cured. The worst prognosis is for anaplastic (ATC) and poorly differentiated thyroid cancer (PDTC). Whenever a local or metastatic advanced disease is present, other treatments are required, varying from local to systemic therapies. In the last decade, the efficacy of the targeted therapies and, in particular, tyrosine kinase inhibitors (TKIs) has been demonstrated. They can prolong the disease progression-free survival and represent the most important therapeutic option for the treatment of advanced and progressive thyroid cancer. Currently, lenvatinib and sorafenib are the approved drugs for the treatment of RAI-refractory DTC and PDTC while advanced MTC can be treated with either cabozantinib or vandetanib. Dabrafenib plus trametinib is the only approved treatment by FDA for BRAFV600E mutated ATC. A new generation of TKIs, specifically for single altered oncogenes, is under evaluation in phase 2 and 3 clinical trials. The aim of this review was to provide an overview of the current and future treatments of thyroid cancer with regards to the advanced and progressive cases that require systemic therapies that are becoming more and more targeted on the molecular identity of the tumor.

Nonthyroidal second primary malignancies in differentiated thyroid cancer patients: Is the incidence increased comparing to the general population and could it be a radioiodine therapy consequence?

The long-term survival of differentiated thyroid cancer (DTC) patients and the need to perform several treatments with radioiodine (131-I) lead to the question if the lifetime risk of developing a nonthyroidal second primary cancer (NTSPC) is increased in these patients. In our study, we assessed the prevalence of NTSPCs in thyroid cancer population and evaluated the possible causative role of 131-I treatment. We analyzed 1096 consecutive patients followed at our institution from 1964 to 1998. A total of 101 NTSPCs were observed in 92/1096 patients (8.4%) among which 17/101 (16.8%) diagnosed before DTC and 84/101 (83.2%) diagnosed after. The most frequent tumor sites observed were breast and bladder/urinary tract in the post-DTC group and breast and hematological system in the pre-DTC group. Regarding 131-I treatment, we did not observe any significant differences regarding either the number of treatments or the cumulative activity. The only significant parameter associated with an increased incidence of NTSPC was follow-up (P = .02): a longer follow-up period was associated with a higher number of NTSPCs. The mean latency between 131-I and NTSPC was 10.52 ± 7.69 years. Comparing with the general Italian population, independent of radioiodine treatment, the standard incidence ratio in our cohort was similar to that of the general population (SIR 1.07) and this result was confirmed by analyzing only the treated group. In conclusion, these results show that the risk of NTSPCs in the DTC patients' population is similar to that in the general population and 131-I treatment was not associated with an increased risk.

DELAYED 131-I FIRST TREATMENT AFTER SURGERY HAS NO IMPACT ON THE MEDIAN TERM OUTCOME OF PATIENTS WITH INTERMEDIATE RISK DIFFERENTIATED THYROID CANCER.

Objective: In intermediate risk (IR) differentiated thyroid cancer (DTC) patients, selective use of radioiodine (131-I) for remnant ablation and/or as adjuvant therapy (RRA) is advocated. The recently suggested postoperative evaluation could delay the use of RRA. The aim of this study was to evaluate if a delayed RRA can worsen the clinical outcome of IR-DTC patients. Methods: Four hundred and fourteen consecutive IR-DTC patients were divided according to the time elapsed from surgery to RRA, <6 months (group A, 186/414 [44.9%]), or ≥6 months (group B, 228/414 [55.1%]). Clinical and biochemical data were collected, and clinical outcome was analyzed at the first evaluation (EV) after RRA (first-EV) and after a median of 6 years of follow-up (last-EV). Results: No difference in the clinical outcome of group A and B was found. Since a different activity of 131-I could have an impact on the outcome, we separately analyzed the groups according to the 131-I activity (low-activity group: 1,110 MBq/30 mCi [n = 320], and high-activity group: 3,700 MBq/100 mCi [n = 94]), further subdivided according to the time elapsed from surgery to RRA. No major differences were found in both the low- and high-activity groups when comparing the features of their subgroups A and B, as far as in their clinical outcome. Conclusion: The time elapsed between surgery and the first 131-I treatment does not influence the clinical outcome of IR-DTC patients. This finding allows a more relaxed attitude in the decision making process whether to perform the RRA in IR-DTC cases in which a selective use of 131-I is recommended. Abbreviations: ATA = American Thyroid Association; DTC = differentiated thyroid cancer; EV = evaluation; HR = high risk; 131-I = radioiodine; IR = intermediate risk; LR = low risk; rhTSH = recombinant human thyroid-stimulating hormone; RRA = radioiodine for remnant ablation; Tg = thyroglobulin; TgAb = thyroglobulin autoantibody; US = ultrasound.

Role of Prophylactic Central Compartment Lymph Node Dissection on the Outcome Of Patients With Papillary Thyroid Carcinoma and Synchronous Ipsilateral Cervical Lymph Node Metastases.

OBJECTIVE: Prophylactic central compartment lymph node dissection (pCCND) results in a higher percentage of surgical-related complications. To date, no evidence of the impact of pCCND on the clinical outcome of papillary thyroid carcinoma (PTC) patients with synchronous ipsilateral cervical lymph node metastases has been reported. METHODS: We evaluated all consecutive patients affected by PTC and synchronous ipsilateral cervical, but without evidence of central compartment, lymph node metastases. We selected 54 consecutive patients (group A) treated by total thyroidectomy, ipsilateral cervical lymph node dissection, and pCCND and 115 patients (group B) matched for sex, age at diagnosis, number and dimension of the metastatic lateral cervical lymph nodes, without pCCND. Clinical outcome after a median of 5 years and surgical-related complications were assessed. RESULTS: The two groups were completely similar in terms of clinical features. Clinical outcomes showed a higher percentage of biochemical and indeterminate but not structural response in group B. Group B required significantly more radioiodine treatments, but no difference was shown in the need to repeat surgery for recurrences. Conversely, the prevalence of permanent hypoparathyroidism was significantly higher in group A (14.8%) than in group B (4.3%). CONCLUSION: In PTC patients with synchronous ipsilateral cervical lymph node metastases, in absence of clinically evident lymph node metastases of the central compartment, performing pCCND does not improve the 5-year outcome in terms of structural disease, despite a greater number of 131I treatments. However, pCCND is severely affected by a higher percentage of permanent hypoparathyroidism, even in the hands of expert surgeons. ABBREVIATIONS: IQR = interquartile range; pCCND = prophylactic central compartment lymph node dissection; PTC = papillary thyroid carcinoma; Tg = thyroglobulin; US = ultrasound.

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.).

The polymorphism rs2480258 within CYP2E1 is associated with different rates of acrylamide metabolism in vivo in humans.

In a recent study, we demonstrated that the variant allele of rs2480258 within intron VIII of CYP2E1 is associated with reduced levels of mRNA, protein, and enzyme activity. CYP2E1 is the most important enzyme in the metabolism of acrylamide (AA) by operating its oxidation into glycidamide (GA). AA occurs in food, is neurotoxic and classified as a probable human carcinogen. The goal of the present study was to further assess the role of rs2480258 by measuring the rate of AA > GA biotransformation in vivo. In blood samples from a cohort of 120 volunteers, the internal doses of AA and GA were assessed by AA and GA adducts to hemoglobin (Hb) measured by mass spectrometry. The rate of biotransformation was assessed by calculating the GA-Hb/AA-Hb ratio. To maximize the statistical power, 60 TT was compared to 60 CC-homozygotes and the results showed that TT homozygotes had a statistically significant reduced rate of biotransformation. Present results reinforced the notion that T-allele of rs2480258 is a marker of low functional activity of CYP2E1. Moreover, we studied the role of polymorphisms (SNPs) within glutathione-S-transferases (GSTs) enzymes and epoxide hydrolase (EPHX), verifying previous findings that SNPs within GSTs and EPHX influence the metabolism rate.

New insights in the molecular signature of advanced medullary thyroid cancer: evidence of a bad outcome of cases with double RET mutations.

BACKGROUND: The RET proto-oncogene is responsible for the pathogenesis of hereditary (98%) and sporadic (40%) medullary thyroid carcinoma (MTC). In sporadic MTC, somatic RET mutations are associated with a poor prognosis. OBJECTIVES: We looked at the genetic profile of patients with advanced and metastatic MTC. The correlation between these mutations and outcome was also investigated. METHODS: 70 patients with advanced and metastatic sporadic MTC were studied. Exons 10-11 and 13-16 of RET were analysed by direct sequencing. All cases were studied for RAS and the majority also for TERT mutations. RET/RAS-negative cases were analysed for other oncogene mutations. RESULTS: 64/70 cases (91.4%) showed a somatic mutation, while 6 (8.6%) were negative. Among the mutated cases, RET mutations, mainly M918T, were the most prevalent (93.8%). K- or H-RAS mutations were present in 6.2% of cases and were mutually exclusive with RET. No other mutations were found. Four tumours showed two RET somatic mutations. We found a complex somatic RET alteration in 6/60 (10%) RET-positive sporadic MTC cases. A positive correlation between a poor prognosis and the multiple number of RET mutations was found. CONCLUSIONS: This study showed a high prevalence of somatic RET mutations in advanced and metastatic MTCs. RAS mutations were present in a small percentage of cases and mutually exclusive with RET mutations. In a small number of cases, more than one RET mutation was present in the same tissue. RET double mutations and, to a lesser extent, also complex mutations showed a worse outcome.

Correlative analyses of RET and RAS mutations in a phase 3 trial of cabozantinib in patients with progressive, metastatic medullary thyroid cancer.

BACKGROUND: Cabozantinib significantly prolonged progression-free survival (PFS) versus a placebo in patients with progressive, metastatic medullary thyroid cancer (MTC; P < .001). An exploratory analysis of phase 3 trial data evaluated the influence of rearranged during transfection (RET) and RAS (HRAS, KRAS, and NRAS) mutations on cabozantinib clinical activity. METHODS: Patients (n = 330) were randomized to cabozantinib (140 mg/day) or a placebo. The primary endpoint was PFS. Additional outcome measures included PFS, objective response rates (ORRs), and adverse events in RET and RAS mutation subgroups. RESULTS: Among all study patients, 51.2% were RET mutation-positive (38.2% with RET M918T), 34.8% were RET mutation-unknown, and 13.9% were RET mutation-negative. Sixteen patients were RAS mutation-positive. Cabozantinib appeared to prolong PFS versus the placebo in the RET mutation-positive subgroup (hazard ratio [HR], 0.23; 95% confidence interval [CI], 0.14-0.38; P < .0001), the RET mutation-unknown subgroup (HR, 0.30; 95% CI, 0.16-0.57; P = .0001), and the RAS mutation-positive subgroup (HR, 0.15; 95% CI, 0.02-1.10; P = .0317). The RET M918T subgroup achieved the greatest observed PFS benefit from cabozantinib versus the placebo (HR, 0.15; 95% CI, 0.08-0.28; P < .0001). The ORRs for RET mutation-positive, RET mutation-negative, and RAS mutation-positive patients were 32%, 22%, and 31%, respectively. No PFS benefit was observed in patients lacking both RET and RAS mutations, although the ORR was 21%. The safety profile for all subgroups was similar to that for the overall cabozantinib arm. CONCLUSIONS: These data suggest that cabozantinib provides the greatest clinical benefit to patients with MTC who have RET M918T or RAS mutations. However, a prospective trial is needed to confirm the relation between genetic variation and the response to cabozantinib. Cancer 2016;122:3856-3864. © 2016 American Cancer Society.

Runs of homozygosity and inbreeding in thyroid cancer.

BACKGROUND: Genome-wide association studies (GWASs) have identified several single-nucleotide polymorphisms (SNPs) influencing the risk of thyroid cancer (TC). Most cancer predisposition genes identified through GWASs function in a co-dominant manner, and studies have not found evidence for recessively functioning disease loci in TC. Our study examines whether homozygosity is associated with an increased risk of TC and searches for novel recessively acting disease loci. METHODS: Data from a previously conducted GWAS were used for the estimation of the proportion of phenotypic variance explained by all common SNPs, the detection of runs of homozygosity (ROH) and the determination of inbreeding to unravel their influence on TC. RESULTS: Inbreeding coefficients were significantly higher among cases than controls. Association on a SNP-by-SNP basis was controlled by using the false discovery rate at a level of q* < 0.05, with 34 SNPs representing true differences in homozygosity between cases and controls. The average size, the number and total length of ROHs per person were significantly higher in cases than in controls. A total of 16 recurrent ROHs of rather short length were identified although their association with TC risk was not significant at a genome-wide level. Several recurrent ROHs harbor genes associated with risk of TC. All of the ROHs showed significant evidence for natural selection (iHS, Fst, Fay and Wu's H). CONCLUSIONS: Our results support the existence of recessive alleles in TC susceptibility. Although regions of homozygosity were rather small, it might be possible that variants within these ROHs affect TC risk and may function in a recessive manner.

Association between CYP2E1 polymorphisms and risk of differentiated thyroid carcinoma.

Differentiated thyroid carcinoma (DTC) results from complex interactions between genetic and environmental factors. Known etiological factors include exposure to ionizing radiations, previous thyroid diseases, and hormone factors. It has been speculated that dietary acrylamide (AA) formed in diverse foods following the Maillard's reaction could be a contributing factor for DTC in humans. Upon absorption, AA is biotransformed mainly by cytochrome P450 2E1 (CYP2E1) to glycidamide (GA). Considering that polymorphisms within CYP2E1 were found associated with endogenous levels of AA-Valine and GA-Valine hemoglobin adducts in humans, we raised the hypothesis that specific CYP2E1 genotypes could be associated with the risk of DTC. Analysis of four haplotype tagging SNPs (ht-SNPs) within the locus in a discovery case-control study (N = 350/350) indicated an association between rs2480258 and DTC risk. This ht-SNP resides within a linkage disequilibrium block spanning intron VIII and the 3'-untranslated region. Extended analysis in a large replication set (2429 controls and 767 cases) confirmed the association, with odds ratios for GA and AA genotypes of 1.24 (95 % confidence interval (CI) 1.03-1.48) and 1.56 (95 % CI, 1.06-2.30), respectively. Functionally, the minor allele was associated with low levels of CYP2E1 mRNA and protein expression as well as lower enzymatic activity in a series of 149 human liver samples. Our data support the hypothesis that inter-individual differences in CYP2E1 activity could modulate the risk of developing DTC suggesting that the exposure to specific xenobiotics, such as AA, could play a role in this process.

A phase 2 trial of lenvatinib (E7080) in advanced, progressive, radioiodine-refractory, differentiated thyroid cancer: A clinical outcomes and biomarker assessment.

BACKGROUND: Lenvatinib is an oral, multitargeted tyrosine kinase inhibitor of the vascular endothelial growth factor receptors 1 through 3 (VEGFR1-VEGFR3), fibroblast growth factor receptors 1 through 4 (FGFR1-FGFR4), platelet-derived growth factor receptor α (PDGFRα), ret proto-oncogene (RET), and v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT) signaling networks implicated in tumor angiogenesis. Positive phase 1 results in solid tumors prompted a phase 2 trial in patients with advanced, radioiodine-refractory, differentiated thyroid cancer (RR-DTC). METHODS: Fifty-eight patients with RR-DTC who had disease progression during the previous 12 months received lenvatinib 24 mg once daily in 28-day cycles until disease progression, unmanageable toxicity, withdrawal, or death. Previous VEGFR-targeted therapy was permitted. The primary endpoint was the objective response rate (ORR) based on independent imaging review. Secondary endpoints included progression-free survival (PFS) and safety. Serum levels of 51 circulating cytokines and angiogenic factors also were assessed. RESULTS: After ≥14 months of follow-up, patients had an ORR of 50% (95% confidence interval [CI], 37%-63%) with only partial responses reported. The median time to response was 3.6 months, the median response duration was 12.7 months, and the median PFS was 12.6 months (95% CI, 9.9-16.1 months). The ORR for patients who had received previous VEGF therapy (n = 17) was 59% (95% CI, 33%-82%). Lower baseline levels of angiopoietin-2 were suggestive of tumor response and longer PFS. Grade 3 and 4 treatment-emergent adverse events, regardless of their relation to treatment, occurred in 72% of patients and most frequently included weight loss (12%), hypertension (10%), proteinuria (10%), and diarrhea (10%). CONCLUSIONS: In patients with and without prior exposure to VEGF therapy, the encouraging response rates, median time to response, and PFS for lenvatinib have prompted further investigation in a phase 3 trial. Cancer 2015;121:2749-2756. © 2015 American Cancer Society.