Objective: The aim of the study was to identify patients with NTRK fusion-positive or RET fusion/mutation-positive thyroid cancers, who could benefit from TRK or RET inhibitors. Methods: Patients were identified in the Calgary prospective thyroid cancer database (N=482). Patients were “pre-screened” with clinically available MassARRAY® BRAF Test, Colon Panel, Melanoma Panel, or ThyroSPEC™. Mutation-negative tumors were “screened” for NTRK fusions and RET fusions/mutations with the Oncomine™ Comprehensive Assay v3 (OCAv3). Results: A total of 86 patients were included in one of two separate analyses. Analysis A included 42 patients with radioactive iodine (RAI)-resistant distant metastases. After pre-screening, 20 BRAF and RAS mutation-negative patients underwent OCAv3 screening, resulting in the detection of four patients with NTRK fusions and four patients with RET fusions (8/20, 40% of analyzed patients). Analysis B included 44 patients, 42 with American Thyroid Association (ATA) high and intermediate risk of recurrence and two with medullary thyroid carcinoma. During pre-screening one patient with an NTRK fusion, one patient with a RET fusion and 30 patients with BRAF mutations were identified. The remaining nine patients received OCAv3 screening, resulting in detection of one patient with an NTRK fusion and one with a RET fusion (4/11, 36% of analyzed patients). Conclusions: Our findings indicate a high rate of NTRK fusions and RET fusions in patients with thyroid cancer with RAI-resistant distant metastases, ATA high/intermediate risk of recurrence. This highlights the importance of early screening, to enable intervention with a TRK or RET inhibitor.

No abstract

Autonomously functioning thyroid nodules are characterized by an increased proliferation and function, which is predominantly caused by constitutively activating TSH receptor mutations leading to an activation of cAMP. In contrast to autonomously functioning thyroid nodules, cold thyroid nodules are functionally inactive and less differentiated. Their molecular cause is still unknown. To further investigate the pathophysiological aspects of autonomously functioning thyroid nodules and to elucidate the molecular etiology of cold thyroid nodules, it is essential to identify genes with differential expression in autonomously functioning thyroid nodules and cold thyroid nodules and to compare this expression to that in normal surrounding tissue. The list of possible candidates for differential regulation ranges from growth factors and their receptors to transcription factors or oncogenes. Therefore, we evaluated the potential of cDNA arrays and studied the expression of 588 known genes from 6 different classes of proteins in thyroid nodules characterized for their function. Forty-seven genes showed a differential expression between nodular and surrounding tissue identified by the expression arrays. The differential expression of 15 transcripts was verified by real-time PCR. About 25% of the transcripts determined by LightCycler PCR are considered false positives because data from PCR and array analysis did not agree. This indicates the reliability of cDNA expression arrays to identify differentially expressed genes in thyroid nodules compared with their surrounding tissue. The 15 selected genes were additionally quantified by real-time PCR in 7 additional cold thyroid nodules, autonomously functioning thyroid nodules, and their surrounding tissues. The highest number of differentially expressed genes was in the group of signal transduction proteins (4 of 38 detectable genes) and extracellular cell signaling and communication proteins (2 of 62 detectable genes). In contrast, transcripts of other classes of proteins were unchanged (e.g. DNA-binding molecules and stress responses). Most of the transcripts were down-regulated in autonomously functioning thyroid nodule and cold thyroid nodule compared with the respective surrounding tissue. This finding could be the result of a dominant activation of a signal transduction pathway, with the cAMP pathway being the likely candidate for autonomously functioning thyroid nodules. The qualitatively similar pattern of changes in this limited number of genes in autonomously functioning thyroid nodules and cold thyroid nodules could suggest a similar dominant activation of a specific signaling cascade in cold thyroid nodules as the constitutively activating mutations in autonomously functioning thyroid nodules.

No abstract