Targeted Oncogene Therapy Before Surgery in Pediatric Patients With Advanced Invasive Thyroid Cancer at Initial Presentation: Is It Time for a Paradigm Shift?

Use of Neoadjuvant Vandetanib in Aggressive Pediatric Medullary Thyroid Carcinoma

Novel use of vandetanib in a child with aggressive MTC with prolonged response to treatment.

Clinical outcomes of combined cervical and transthoracic surgical approaches in patients with advanced thyroid cancer

BACKGROUND

Advanced thyroid disease involving the mediastinum may be managed surgically with a combined transcervical and transthoracic approach. Contemporary analysis of this infrequently encountered cohort will aid the multidisciplinary team in personalizing treatment approaches.

METHODS

Retrospective review of patients undergoing combined transcervical and transthoracic surgery for thyroid cancer at a single high-volume institution from 1994 to 2015.

RESULTS

Thirty-eight patients with median age 59 years (range 28-76) underwent surgery without perioperative mortality. Most patients had primary disease. A majority had distant metastases outside the mediastinum but had locoregionally curable disease. Common complications were temporary (39%) and permanent (18%) hypoparathyroidism, and wound infection (13%). One-year overall survival was 84%; 1-year locoregional disease-free survival was 64%. Median time to locoregional recurrence was 36 months. Only esophageal invasion was associated with worse oncologic outcomes.

CONCLUSIONS

Combined transcervical and transthoracic surgery for advanced thyroid cancer can be performed without mortality and with acceptable morbidity.

Pediatric thyroid cancer: Recent developments

Thyroid cancer is rare in children but its incidence is increasing. Recent data have clarified important similarities and differences between thyroid cancers originating in childhood and in adulthood. The genetic drivers of pediatric thyroid cancers are similar to those in adult tumors but comprise more gene fusions and fewer point mutations. Clinically, despite frequent metastatic spread, pediatric thyroid cancer has an excellent prognosis and mortality is rare. Therefore, treatment approaches must weigh carefully the morbidity of thyroid cancer treatments against their benefits. Current key questions include which children require total thyroidectomy rather than more limited-and safer-lobectomy, and in which children does the benefit of radioactive iodine therapy outweigh its risk of inducing a secondary malignancy. Finally, molecular therapies targeting genetic drivers of thyroid cancer now provide effective treatment for children with progressive, radioiodine-refractory disease, as well as opportunities to explore novel neoadjuvant uses that facilitate therapeutic surgery or radioactive iodine.

Evaluation of the Molecular Landscape of Pediatric Thyroid Nodules and Use of a Multigene Genomic Classifier in Children

Question

Are pediatric thyroid nodules amenable to cancer prediction by genomic classification?

Findings

In this retrospective study of 95 pediatric patients with thyroid nodules, surgical samples underwent next-generation sequencing and genomic classification. Testing defined the unique molecular landscape of pediatric thyroid nodules (which, as opposed to adults, comprised more frequent gene fusions and DICER1 variants) and identified a sensitivity of 96% and specificity of 78% regarding cancer detection.

Meaning

The study results suggest that although the molecular landscape of pediatric thyroid nodules is different than in adults, it remains amenable to multigene genomic classification, which may help prevent potentially unnecessary diagnostic surgeries.

Importance

Definitive diagnosis of a thyroid nodule in a child is obtained through diagnostic surgery. This is problematic because pediatric thyroid surgery is associated with higher rates of complications. In adults, preoperative molecular testing improves the management of thyroid nodules, but this has not been validated in children.

Objective

To determine whether the molecular landscape of pediatric thyroid nodules is amenable to detection by a multigene genomic classifier (GC) test (ThyroSeq v3; Sonic Healthcare USA).

Design, Setting, and Participants

This was a retrospective consecutive case series and GC testing of fine-needle aspiration (FNA) and formalin-fixed paraffin-embedded (FFPE) tissues from sequential pediatric thyroidectomies performed between January 2003 and December 2019 at a single tertiary academic medical center. The study included 95 patients (median [range] age, 16.3 [4.8 to 21.1] years; 75 [79%] female) who underwent surgery for a thyroid nodule.

Interventions

A total of 118 thyroid nodule samples (95 FFPE, 23 companion FNAs) yielded informative next-generation sequencing data and multigene GC.

Main Outcomes and Measures

The primary outcome was the determination of the pediatric thyroid molecular landscape. The secondary outcome was the diagnostic accuracy of the GC test for pediatric thyroid nodules.

Results

Of the 95 patients, 75 (79%) were female, and the median (IQR) age was 16.3 (14.0-17.3) years. Next-generation sequencing confirmed the unique molecular landscape of malignant pediatric thyroid nodules (compared with adults), which is dominated by gene fusions (most commonly RET and NTRK), rare BRAF/RAS alterations, and no TP53 or TERT promoter pathogenic variants. Several poorly differentiated thyroid cancers harbored DICER1 variants. Benign nodules appeared to be almost exclusively associated with TSHR and DICER1 alterations. The test demonstrated a 96% sensitivity (95% CI, 87%-99%) and 78% specificity (95% CI, 64%-88%). The negative predictive value was 95% (95% CI, 88%-98%) and the positive predictive value was 83% (95% CI, 74–89%). The concordance of GC between 23 pairs of matched FFPE and FNA tissues was 96%.

Conclusions and Relevance

The study results of this retrospective consecutive case series suggest that the molecular landscape of pediatric nodules is unique but remains amenable to molecular classification. The multigene GC test, with high sensitivity and reasonably high specificity, represents a potential addition to the diagnostic workup of children with thyroid nodules and may decrease the use of diagnostic surgery.

The clinical aspect of NTRK-fusions in pediatric papillary thyroid cancer

Although adult and pediatric papillary thyroid cancer (PTC) share similar oncogenic drivers, they differ in the pathological features and outcomes of the disease. In adults with PTC, the most frequent genetic alterations are mutually exclusive point mutations in BRAFV600E or the RAS family with BRAFV600E commonly associated with invasive disease and decreased response to radioiodine therapy. In pediatric PTC, fusion oncogenes involving chromosomal translocations in tyrosine kinase (TK) receptors, most commonly RET and NTRK, are often found in patients with lateral neck and distant metastases. This brief report reviews clinical data from a single-institute's cohort of NTRK-driven pediatric PTC cases with an updated review of the literature and comparison to adult NTRK-driven PTC.

Outcome of Patients with Locally Advanced Metastatic Medullary Thyroid Cancer and Induction Therapy with Tyrosine Kinase Inhibitors in Slovenia

BACKGROUND

The aim of our retrospective study was to evaluate the outcome of patients with metastatic medullary thyroid cancer (MTC) treated with tyrosine kinase inhibitors (TKIs) and/or chemotherapy with the emphasis on analysis on the cohort treated by induction TKI because of locally advanced metastatic MTC.

METHODS

We analyzed the outcome of 30 patients (21 males, 9 females; median age 63.8 years) with metastatic MTC treated between 2000-2020. Sunitinib was used in 20 patients.

RESULTS

Median progression-free survival on TKI and on chemotherapy was 10.6 (95% CI 7.1-14) months and 3.5 (95% CI 1.4-5.5) months, respectively. Median overall survival from diagnosis and from metastasis presentation was 38.2 (95% CI 4.7-71.7) months and 20.9 (95% CI 13.8-27.9) months, respectively. Eight patients (five females, three males; 58-86 years of age, median age 70 years) were treated with induction TKI because of inoperable locally advanced and metastatic MTC. The response rate to induction TKI was 50%; two patients (25%) had stable disease, and two patients (25%) had progressive disease.

CONCLUSION

Our data support a new paradigm that TKIs may be the first treatment option in selected patients with locally advanced metastatic MTC, followed by locoregional treatment with surgery and/or external beam radiotherapy. Further studies are required to consolidate the presented data.

Clinical Outcomes of Diffuse Sclerosing Variant Papillary Thyroid Carcinoma in Pediatric Patients

OBJECTIVES/HYPOTHESIS

The diffuse sclerosing variant of papillary thyroid carcinoma (DSV) may be more aggressive than conventional well-differentiated non-DSV related papillary thyroid carcinomas (N-PTC).

STUDY DESIGN

Retrospective chart review.

METHODS

Retrospective review of clinical outcomes for patients 21 years of age or younger who underwent initial surgery for PTC at a single institution from January 1, 2005 to April 1, 2020. Genomic analysis was performed using targeted next-generation sequencing. Data were analyzed using Fischer's exact test and Kaplan-Meier curve log-rank test.

RESULTS

Our cohort consisted of 72 patients, nine with DSV and 63 with N-PTC. Age at diagnosis was comparable (15.4 vs. 16.2 years, respectively, P = .46). DSV were more likely to be in the high-risk American Thyroid Academy pediatric risk group (100% vs. 41.3%, P = .004), to present with regional cervical lymph node metastases (100% vs. 60.3%, P = .036), and to present with distant metastases (67% vs. 22%, P = .005). No mortality seen in either group over 27.5 (interquartile range 14.8, 46.00) months average follow-up. Throughout the follow-up period, DSV were more likely to experience progression than N-PTC (hazard ratio = 5.7 [95% confidence interval 1.7-20.0; P = .0056]). In a subset of 19 patients with aggressive disease who had molecular testing as part of clinical care we detected RET fusions in nearly all DSV compared to a minority of N-PTC (83% vs. 15.4%, P = .0095).

CONCLUSIONS

Pediatric patients with DSV have more advanced disease at diagnosis and are more likely to experience progression of disease compared to patients with N-PTC. The prevalence of RET fusions in our cohort recapitulates the frequency of this alteration described in prior studies.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

NTRK- and RET-fusion-directed therapy in pediatric thyroid cancer yields a tumor response and radioiodine uptake

BACKGROUND

Molecular characterization in pediatric papillary thyroid cancer (PTC), distinct from adult PTC, is important for developing molecular targeted therapies for progressive 131I-refractory PTC.

METHODS

PTC samples from 106 pediatric patients (age: 4.3-19.8 years; 21 boys) who attended Seoul National University Hospital (January 1983-March 2020) were available for genomic profiling. Previous transcriptome data from 125 adult PTCs were used for comparison.

RESULTS

Genetic drivers were found in 80 tumors; 31 with fusion oncogenes (RET in 21, ALK in 6, and NTRK1/3 in 4), 47 with point mutations (BRAFV600E in 41, TERTC228T in 2, and DICER1 variants in 5), and 2 with amplifications. Fusion-oncogene PTCs, predominantly detected in younger patients, presented with a more advanced stage and showed more recurrent or persistent disease than BRAFV600E PTCs, which were detected mostly in adolescents. Pediatric fusion PTCs (in those aged < 10 years) showed lower expression of thyroid differentiation genes, including SLC5A5, than adult fusion PTCs. Two girls with progressive 131I-refractory lung metastases harboring a TPR-NTRK1 or CCDC6-RET fusion received fusion-targeted therapy; larotrectinib and selpercatinib decreased the tumor extent and restored radioiodine uptake. The girl with the CCDC6-RET fusion received 131I therapy combined with selpercatinib, leading to a tumor response. In vitro 125I uptake and 131I clonogenic assays showed that larotrectinib inhibited growth and restored radioiodine avidity.

CONCLUSIONS

In pediatric fusion-oncogene PTC cases with 131I-refractory advanced disease, selective fusion-directed therapy may restore radioiodine avidity and lead to a dramatic tumor response, underscoring the importance of molecular testing in pediatric PTC patients.

FUNDING

The Ministry of Science, ICT & Future Planning (grant number NRF-2016R1A2B4012417 91 and 2019R1A2C2084332), the Ministry of Health & Welfare, Republic of Korea (grant number 92 H14C1277), the Ministry of Education (grant number 2020R1A6A1A03047972), and the Seoul 93 National University Hospital Research Fund (grant number 04-2015-0830).

Canadian Consensus for Biomarker Testing and Treatment of TRK Fusion Cancer in Pediatric Patients

Neurotrophic tyrosine receptor kinase gene fusions (NTRK) are oncogenic drivers present at a low frequency in most tumour types (<5%), and at a higher frequency (>80%) in a small number of rare tumours (e.g., infantile fibrosarcoma [IFS]) and considered mutually exclusive with other common oncogenic drivers. Health Canada recently approved two tyrosine receptor kinase (TRK) inhibitors, larotrectinib (for adults and children) and entrectinib (for adults), for the treatment of solid tumours harbouring NTRK gene fusions. In Phase I/II trials, these TRK inhibitors have demonstrated promising overall response rates and tolerability in patients with TRK fusion cancer who have exhausted other treatment options. In these studies, children appear to have similar responses and tolerability to adults. In this report, we provide a Canadian consensus on when and how to test for NTRK gene fusions and when to consider treatment with a TRK inhibitor for pediatric patients with solid tumours. We focus on three pediatric tumour types: non-rhabdomyosarcoma soft tissue sarcoma/unspecified spindle cell tumours including IFS, differentiated thyroid carcinoma, and glioma. We also propose a tumour-agnostic consensus based on the probability of the tumour harbouring an NTRK gene fusion. For children with locally advanced or metastatic TRK fusion cancer who have either failed upfront therapy or lack satisfactory treatment options, TRK inhibitor therapy should be considered.