New national recommendations for the treatment of pediatric differentiated thyroid carcinoma in the Netherlands.

BACKGROUND: Currently, there are no European recommendations for the management of pediatric thyroid cancer. Other current international guidelines are not completely concordant. In addition, medical regulations differ between, for instance, the US and Europe. We aimed to develop new, easily accessible national recommendations for differentiated thyroid carcinoma (DTC) patients <18 years of age in the Netherlands as a first step toward a harmonized European Recommendation. METHODS: A multidisciplinary working group was formed including pediatric and adult endocrinologists, a pediatric radiologist, a pathologist, endocrine surgeons, pediatric surgeons, pediatric oncologists, nuclear medicine physicians, a clinical geneticist and a patient representative. A systematic literature search was conducted for all existing guidelines and review articles for pediatric DTC from 2000 until February 2019. The Appraisal of Guidelines, Research and Evaluation (AGREE) instrument was used for assessing quality of the articles. All were compared to determine dis- and concordances. The American Thyroid Association (ATA) pediatric guideline 2015 was used as framework to develop specific Dutch recommendations. Discussion points based upon expert opinion and current treatment management of DTC in children in the Netherlands were identified and elaborated. RESULTS: Based on the most recent evidence combined with expert opinion, a 2020 Dutch recommendation for pediatric DTC was written and published as an online interactive decision tree (www.oncoguide.nl). CONCLUSION: Pediatric DTC requires a multidisciplinary approach. The 2020 Dutch Pediatric DTC Recommendation can be used as a starting point for the development of a collaborative European recommendation for treatment of pediatric DTC.

A unique case of two somatic APC mutations in an early onset cribriform-morular variant of papillary thyroid carcinoma and overview of the literature.

We report a case of a 22-year-old female patient who was diagnosed with a cribriform-morular variant of papillary thyroid carcinoma (CMV-PTC). While at early ages this thyroid cancer variant is highly suggestive for familial adenomatous polyposis (FAP), there was no family history of FAP. In the tumor biallelic, inactivating APC variants were identified. The patient tested negative for germline variants based on analysis of genomic DNA from peripheral blood leukocytes. Somatic mosaicism was excluded by subsequent deep sequencing of leukocyte and normal thyroid DNA using next generation sequencing (NGS). This report presents a rare sporadic case of CMV-PTC, and to the best of our knowledge the first featuring two somatic APC mutations underlying the disease, with an overview of CMV-PTC cases with detected APC and CTNNB1 pathogenic variants from the literature.

Targetable gene fusions identified in radioactive iodine refractory advanced thyroid carcinoma.

Objective Gene alterations leading to activation of the MAPK pathway are of interest for targeted therapy in patients with advanced radioactive iodine refractory (RAI-R) thyroid carcinoma. Due to technical reasons gene fusion analysis in RNA isolated from formalin-fixed tumor tissues has till now been limited. The objective of the present study was to identify targetable gene rearrangements in RNA isolated from formalin-fixed RAI-R thyroid carcinomas. Design Retrospective study in 132 patients with RAI-R thyroid carcinoma (59 papillary-, 24 follicular-, 35 Hürthle cell- and 14 anaplastic thyroid carcinoma). Methods Total nucleic acid (undivided DNA and RNA) was isolated from formalin-fixed tissue. Extensive gene fusion analysis was performed in all samples that tested negative for pathogenic BRAF, NRAS, HRAS and KRAS variants. Results Seven targetable gene fusions were identified in the remaining 60 samples without known DNA variants. This includes frequently reported gene fusions such as CCDC6/RET (PTC1), PRKAR1A/RET (PTC2) and ETV6/NTRK3 , and gene fusions that are less common in thyroid cancer (TPM3/NTRK1, EML4/ALK and EML4/NTRK3). Of note, most gene fusions were detected in papillary thyroid carcinoma and MAPK-associated alterations in Hürthle cell carcinomas are rare (2/35). Conclusion Targetable gene fusions were found in 12% of RAI-R thyroid carcinoma without DNA variants and can be effectively identified in formalin-fixed tissue. These gene fusions might provide a preclinical rationale to include specific kinase inhibitors in the treatment regimen for these patients. The latter intends to restore iodine transport and/or take advantage of the direct effect on tumor cell vitality once progressive disease is seen.

A new explanation for recessive myotonia congenita: exon deletions and duplications in CLCN1.

OBJECTIVE: To assess whether exon deletions or duplications in CLCN1 are associated with recessive myotonia congenita (MC). METHODS: We performed detailed clinical and electrophysiologic characterization in 60 patients with phenotypes consistent with MC. DNA sequencing of CLCN1 followed by multiplex ligation-dependent probe amplification to screen for exon copy number variation was undertaken in all patients. RESULTS: Exon deletions or duplications in CLCN1 were identified in 6% of patients with MC. Half had heterozygous exonic rearrangements. The other 2 patients (50%), with severe disabling infantile onset myotonia, were identified with both a homozygous mutation, Pro744Thr, which functional electrophysiology studies suggested was nonpathogenic, and a triplication/homozygous duplication involving exons 8-14, suggesting an explanation for the severe phenotype. CONCLUSIONS: These data indicate that copy number variation in CLCN1 may be an important cause of recessive MC. Our observations suggest that it is important to check for exon deletions and duplications as part of the genetic analysis of patients with recessive MC, especially in patients in whom sequencing identifies no mutations or only a single recessive mutation. These results also indicate that additional, as yet unidentified, genetic mechanisms account for cases not currently explained by either CLCN1 point mutations or exonic deletions or duplications.

Identification of structural differences between different forms of interleukin-2 (IL-2) using anti-(human recombinant) IL-2 monoclonal antibodies.

We have generated a panel of murine monoclonal antibodies (mAbs) directed against recombinant human interleukin-2 (rh IL-2). All mAbs have similar affinities (Kaff approximately equal to 10(-8) M) and are of the IgG1 isotype. Specificity of the mAbs has been established using an ELISA method and immunoprecipitation of native human interleukin-2 (nh IL-2) present in supernatants from PHA-stimulated human mononuclear cells (PBMNC). Four of the nine mAbs inhibit the rh IL-2-dependent proliferation of a murine cytotoxic T-lymphocyte line (CTLL-2). The estimated ID50, in the presence of 0.75 IU rh IL-2/ml, ranges from 2.0 micrograms/ml to 30 micrograms/ml final concentrations of the antibodies. Using different forms of IL-2 we found that the mAbs give different patterns of inhibition of the IL-2-dependent proliferation. One mAb (AMCIB 27) is able to discriminate between rh and nh IL-2. Findings with another mAb (AMCIB 24) indicate that possible functional differences between human IL-2 and recombinant murine (rm) IL-2 are caused by differences in the active sites. The results of this investigation show that it is possible to obtain mAbs, after immunization with rh IL-2, that differ in their ability to inhibit the biological action of different forms of IL-2.