Enrichment of SOX2-Positive Cells in BRAF V600E Mutated and Recurrent Ameloblastoma

Ameloblastoma is the most common benign odontogenic neoplasm, but with an aggressive behavior and a high recurrence rate. Nowadays wide surgical resection is the current recommended treatment, which can cause further loss of function and esthetics. Recent studies point to the stem/progenitor cells as both initiators and propagators of the tumors. Elucidation of the cellular and molecular mechanisms underlying the tumor stem cells is of broad interest for understanding tumorigenesis and for developing effective targeted therapies. SRY related HMG box gene 2 (SOX2) is a transcription factor that plays important roles in development, stem cell renewal, and cancer formation. Few studies have revealed increased SOX2 expression in atypical ameloblastoma and ameloblastic carcinoma. For the development of personalized medicine for ameloblastoma, biomarkers that provide prognostic or predictive information regarding a tumor’s nature or its response to treatment are essential. Thus, in this study, we aimed to study if SOX2-positive cells exist in ameloblastomas and their correlation with the clinicopathologic parameters. Our data suggested BRAF(V600E) mutation might contribute to the expansion of SOX2-positive cells. The identification of BRAF(V600E) mutation and the amplification of SOX2-positive cells in ameloblastomas imply the possible benefit of applying BRAF and SOX2 inhibitors in recurrent and un-resectable ameloblastomas.

Genetic Study of BRAF V600E and SMO L412F Mutations in Japanese Patients with Ameloblastoma

Background and aim: Ameloblastoma is a benign, intraosseous, progressively growing, epithelial, odontogenic neoplasm. BRAF and SMO mutations have been reported in ameloblastoma. In this study, we evaluated BRAF V600E and SMO L412F mutations; and assessed the relationship between BRAF V600E mutant expression and the clinicopathological features in Japanese patients with ameloblastoma. Methods: We examined 24 formalin-fixed paraffin-embedded samples. All specimens were from patients with mandibular ameloblastoma: 20 were conventional ameloblastoma and 4 were unicystic ameloblastoma. The BRAF V600E mutation was assessed by Sanger sequencing and immunohistochemistry, and the SMO L412F mutation was assessed only by Sanger sequencing. Results: Twenty of the 24 (83%) ameloblastoma samples carried the BRAF V600E mutation; 22 of the 24 (92%) samples were immunohistochemically positive for BRAF V600E. However, the SMO L412F mutation was not detected in any of them. The BRAF V600E mutation status did not correlate with the clinicopathological features, such as age, sex, location, method, recurrence, and subtype. Conclusion: BRAF inhibitors could be a potential treatment option for Japanese patients with ameloblastoma, harboring the BRAF V600E mutation.

Molecular Analysis of Colorectal Cancers Suggests a High Frequency of Lynch Syndrome in Indonesia

There is about three times higher incidence of young patients <50 years old with colorectal cancer, termed EOCRC, in Indonesia as compared to Europe, the UK and USA. The aim of this study was to investigate the frequency of Lynch Syndrome (LS) in Indonesian CRC patients. The previously described Nottingham Lynch Syndrome Test (N_LyST) was used in this project. N_LyST is a robust high-resolution melting (HRM)-based test that has shown 100% concordance with standard reference methods, including capillary electrophoresis and Sanger sequencing. The test consisted of five mononucleotide microsatellite markers (BAT25, BAT26, BCAT25, MYB, EWSR1), BRAF V600E mutation and MLH1 region C promoter for methylation (using bisulphite-modified DNA). A total of 231 archival (2016–2019) formalin-fixed, paraffin-embedded (FFPE) tumour tissues from CRC patients collected from Dr. Sardjito General Hospital Yogyakarta, Indonesia, were successfully tested and analysed. Among those, 44/231 (19.05%) were MSI, 25/231 (10.82%) were harbouring BRAF V600E mutation and 6/231 (2.60%) had MLH1 promoter methylation. Almost all—186/197 (99.45%)—MSS cases were MLH1 promoter unmethylated, while there were only 5/44 (11.36%) MSI cases with MLH1 promoter methylation. Similarly, only 9/44 (20.45%) of MSI cases were BRAF mutant. There were 50/231 (21.65%) EOCRC cases, with 15/50 (30%) regarded as MSI, as opposed to 29/181 (16.02%) within the older group. In total, 32/231 patients (13.85%) were classified as “Probable Lynch” (MSI, BRAF wildtype and MLH1 promoter unmethylated), which were enriched in EOCRC as compared to older patients (24% vs. 11.05%, p = 0.035). Nonetheless, 30/50 (76.00%) cases among the EOCRC cases were non-LS (sporadic) and were significantly associated with a left-sided tumour. The overall survival of both “Probable Lynch” and non-LS (sporadic) groups (n = 227) was comparable (p = 0.59), with follow up period of 0–1845 days/61.5 months. Stage, node status, histological grading and ECOG score were significantly associated with patient overall survival (p < 0.005), yet only ECOG was an independent factor for OS (HR: 4.38; 95% CI: 1.72–11.2; p = 0.002). In summary, this study is the first to reveal a potentially higher frequency of LS among CRC patients in Indonesia, which may partially contribute to the reported much higher number of EOCRC as compared to the incidence in the West.

BRAF-mutant melanoma of the skin during pregnancy with dichorionic diamniotic twins. Clinical case

Per the majority of authors, melanoma is the most common tumor diagnosed during pregnancy (31 % of all malignant neoplasms). In approximately 1/3 of women melanoma developed in child-bearing age is diagnosed during pregnancy or in the postpartum period. However, only some retrospective studies analyzed the effect of pregnancy on melanoma development, and conclusive data on development, progression and treatment of BRAF-mutant melanoma is lacking. In this subpopulation of patients, BRAF status supposedly can negatively affect disease outcome irrespective of treatment methods.The article presents a clinical case of recurrence of melanoma with the BRAF V600E mutation during pregnancy. The patient underwent lymph node dissection during pregnancy prolongation, after labor she received antitumor drug therapy with МЕК and ВRAF inhibitors. Melanoma recurrence during pregnancy did not worsen treatment outcomes for the mother and embryo.

ACT-8 Current status and prospects for the treatment of malignant glioma using cancer gene panel tests

Introduction: The cancer gene panel test was covered by insurance in June 2019. Our institution started the test in May 2020 and has experienced 10 cases, so we will report on the current status and future prospects. Methods: The subjects were 10 patients who underwent the cancer gene panel test using FoundationOne CDx. Results:The cases included 8 glioblastomas, an anaplastic astrocytoma, and an anaplastic oligodendroglioma. The total number of tumor mutational burden (TMB) was judged to be low in all cases, and the microsatellite instability test (MSI) showed no instability in all cases (MSI-Stable). The total number of genetic changes detected was 11 ± 5.0, oncogene mutations were 5.3 ± 2.4, and gene mutations of unknown relevance to cancer were 5.7 ± 2.8. Major oncogene mutations were IDH1 mutation in 4 cases, ATRX mutation in 2 cases, TP53 mutation in 6 cases, and BRAF V600E mutation in 1 case. Based on the test results, a 25-year-old man with BRAF V600E mutation was initiated into the NCCH1901 study (Patient-Proposed Healthcare Services). A case with IDH1 mutation (47-year-old male) entered a phase I clinical trial of a mutant IDH1 inhibitor. It is estimated that the chance of finding an appropriate drug by cancer gene panel test is about 10–20%. However, in cases that are resistant to standard treatment, the benefits can be expected if the drugs associated with the cancer gene panel test can be used. Conclusions: Although Malignant gliomas are often TMB-low and MSI-stable and the response rate to molecular-targeted drugs and other therapies is not high, there are some cases that can be salvaged by performing the cancer gene panel test. It is suggested that the active use of cancer gene panel test may contribute to the development of new drugs with high response rates and the improvement of prognosis.

What's New in Molecular Targeted Therapies for Thyroid Cancer?

Thyroid cancer refers to various cancers arising from thyroid gland. Differentiated thyroid cancers (DTCs) include papillary, follicular, and Hurthle cell carcinomas and represent cancers retain normal thyroid functions such as iodine uptake. Radioactive iodine (RAI) is generally used for upfront treatment of metastatic DTCs, but RAI refractory DTCs remain to be clinical challenges. Sorafenib and lenvatinib were approved for the treatment of RAI refractory DTCs and more recently, genomics-based targeted therapies have been developed for NTRK and RET gene fusion-positive DTCs. Poorly differentiated and anaplastic thyroid cancers (ATCs) are extremely challenging diseases with aggressive courses. BRAF/MEK inhibition has been proven to be highly effective in BRAF V600E mutation-positive ATCs and immune checkpoint inhibitors have shown promising activities. Medullary thyroid cancers, which arise from parafollicular cells of thyroid, represent a unique subset of thyroid cancer and mainly driven by RET mutation. In addition to vandetanib and cabozantinib, highly specific RET inhibitors such as selpercatinib and pralsetinib have demonstrated impressive activity and are in clinical use.