Mutated BRAF and personalised medicine in differentiated thyroid cancer

Vascular Endothelial Growth Factor Receptor Inhibitors in Chinese Patients With Advanced Radioactive Iodine-Refractory Differentiated Thyroid Cancer: A Network Meta-Analysis and Cost-Effectiveness Analysis

INTRODUCTION

Two targeted drugs (apatinib and lenvatinib) show clinical efficacy in first-line treatment of Chinese patients with radioactive advanced iodine-refractory differentiated thyroid cancer (RAIR-DTC) and are recommended by the Chinese Society of Clinical Oncology guidelines. Considering the high clinical cost of long-term vascular endothelial growth factor receptor inhibitor administration and to determine which of the two targeted drugs is preferable, we opted to conduct a cost-effectiveness analysis (CEA) and network meta-analysis (NMA).

MATERIAL AND METHODS

The results of NMA and CEA included in the two phase III randomized clinical trials REALITY (NCT03048877) and Study-308 (NCT02966093), in which Bayesian NMA and CEA were performed on 243 and 149 Chinese patients, respectively, were retrieved. Overall survival and progression-free survival (PFS) for apatinib versus lenvatinib were determined by NMA. CEA involved the development of a 20-year Markov model to obtain the total cost and quality-adjusted life-years (QALYs), and this was followed by sensitivity and subgroup analyses.

RESULTS

Compared with lenvatinib, apatinib therapy provided a 0.837 improvement in QALY and $6,975 reduction in costs. The hazard ratio of apatinib versus lenvatinib and the cost of the targeted drugs had a significant impact on the model. According to the sensitivity analysis, apatinib was more cost-effective and had no correlation with willingness-to-pay in China. Subgroup analysis showed that apatinib maintained PFS more economically.

CONCLUSION

NMA and CEA demonstrated that apatinib was more cost-effective compared to lenvatinib in the first-line treatment of Chinese RAIR-DTC patients.

Ultrasound-guided implantation of radioactive 125I seed in radioiodine refractory differentiated thyroid carcinoma

BACKGROUND

Treatment for radioiodine refractory differentiated thyroid carcinoma (RR-DTC) is challenging. The purpose of this study was to assess the efficacy and safety of ultrasound-guided implantation of radioactive ¹²⁵I-seed in radioiodine refractory differentiated thyroid carcinoma.

METHODS

Thirty-six cervical metastatic lymph nodes (CMLNs) diagnosed with RR-DTC from 18 patients were enrolled in this retrospective study. US and contrast-enhanced ultrasound (CEUS) examinations were performed before implantation. Follow-up comprised US, CEUS, thyroglobulin (Tg) level and routine hematology at 1-3, 6, 9 and 12 months and every 6 months thereafter. The volumes of the nodules were compared before implantation and at each follow-up point. The volume reduction rate (VRR) of nodules was also recorded.

RESULTS

The median volume of the nodules was 523 mm³ (148, 2010mm³) initially, which decreased significantly to 53mm³ (0, 286mm³) (P < 0.01) at the follow-up point of 24 months with a median VRR as 95% (86,100%). During the follow-up period (the range was 24-50 months), 25 (69%) nodules had VRR greater than 90%, of which 12 (33%) nodules had VVR ≈ 100% with unclear structures and only ¹²⁵I seed images were visible in the US. At the last follow-up visit, the serum Tg level decreased from 57.0 (8.6, 114.8) ng/ml to 4.9 (0.7, 50.3) ng/ml, (P < 0.01).

CONCLUSION

US-guided ¹²⁵I seed implantation is safety and efficacy in treating RR- DTC. It could be an effective supplement for the comprehensive treatment of thyroid cancer.

A double mutation of BRAF L597Q and V600E in situ and solitary brain metastasis of occult papillary thyroid carcinoma: A case report

RATIONALE

The rare BRAF L597Q (c.T1790A) point mutation has been previously reported in childhood acute lymphoblastic leukemia. We present the first rare case of occult papillary thyroid carcinoma with BRAF L597Q mutation in a Tibetan patient.

PATIENT CONCERNS

A 57-year-old male patient presented with a protruding mass on the left forehead for 2 years and numbness in the right limb for 3 weeks.

DIAGNOSES

The patient had a double mutation of BRAF L597Q and V600E in 2 separate lesions at thyroid and brain, the immunohistochemical staining showed that the cytokeratin (CK), thyroglobulin (Tg) and thyroid transforming factor-1 (TTF-1) were immunoreactive. All the findings supported the diagnosis of solitary brain metastasis of occult papillary thyroid carcinoma.

INTERVENTIONS

The patient underwent left frontal lobe metastasis (thyroid cancer) resection that involved craniectomy and artificial skull repair.

OUTCOMES

During the 24-month follow-up, no postoperative complications or recurrence and metastasis were found.

LESSONS

This is the first case of solitary brain metastasis of occult papillary thyroid carcinoma with double mutation of BRAF L597Q and V600E in 2 separate lesions reported in the literature. Our study extends the disease spectrum of occult papillary thyroid carcinoma and suggests that the BRAF L597Q mutation might play a specific role in inducing the solitary brain metastasis of occult papillary thyroid carcinoma in a Chinese Tibetan patient, but the detailed molecular mechanism remains to be confirmed by a large number of functional experiments and clinical research.

VE1 Immunohistochemistry Improves the Limit of Genotyping for Detecting BRAFV600E Mutation in Papillary Thyroid Cancer

Detection of BRAF^V600E is useful for making diagnosis and risk stratification of papillary thyroid carcinoma (PTC). Molecular testing, however, is not always available for routine clinical use. To assess the clinical utility and reliability of VE1 immunohistochemistry (IHC) for detecting BRAF^V600E mutation in PTC, VE1 IHC was performed on the tissue microarrays of 514 patients with PTC and was compared with Sanger sequencing results. Of 514 PTC cases, 433 (84.2%) were positive for VE1 expression. Among 6 discordant cases between VE1 IHC and Sanger sequencing, 3 initial VE1-false negative cases turned out to be true false negative on repeat testing, and 3 VE1-false positive cases showed BRAF^V600E mutation using digital PCR analysis. PTCs with low variant allele fraction were positive for VE1 IHC but were not detected using sequencing. VE1 IHC showed 99.3% sensitivity, 100% specificity, 100% positive predictive value, and 96.4% negative predictive value. The BRAF^V600E mutation was significantly associated with older age, multifocality, extrathyroidal extension, lymph node metastasis, and advanced tumor stage. In conclusion, VE1 IHC is a reliable method for detecting BRAF^V600E mutation in PTC specimens.

Targeted next generation sequencing identifies somatic mutations and gene fusions in papillary thyroid carcinoma

138 papillary thyroid carcinoma (PTC) samples were assessed for somatic mutation profile and fusion genes by targeted resequencing using a cancer panel (ThyGenCap^TM) targeting 244 cancer-related genes and 20 potential fusion genes. At least one genetic alteration (including mutations and fusion genes) was observed in 118/138 (85.5%) samples. The most frequently mutated gene was BRAF V600E (57.2%). Moreover, we identified 11 fusion genes including eight previously reported ones and three novel fusion genes, UEVLD-RET, OSBPL9-BRAF, and SQSTM1-NTRK3. Alterations affecting the mitogen-activated protein kinase (MAPK) signaling pathway components were seen in 69.6% of the PTC cases and all of these driver mutations were mutually exclusive. Univariate analysis ascertained that the fusion genes were strongly associated with distinct clinicopathological characteristics, such as young age, local invasion, extensive metastasis, and disease stage. In conclusion, our approach facilitated simultaneous high-throughput detection of gene fusions and somatic mutations in PTC samples.