It was not possible to detect BRAF V600E mutation in circulating cell-free DNA from patients with ameloblastoma: A diagnostic accuracy study.

The objective of this study is to evaluate the diagnostic accuracy of plasma-based liquid biopsy for the detection of the BRAF V600E mutation in circulating cell-free DNA from patients with ameloblastoma. This is a prospective diagnostic accuracy study conducted based on the Standards for Reporting Diagnostic Accuracy recommendations. The index test was the plasma-based liquid biopsy, whereas the reference standard was the conventional tissue biopsy. The target condition was the detection of BRAF V600E mutation. The study population consisted of individuals with ameloblastoma recruited from three tertiary hospitals from Brazil. A negative control group composed of three individuals with confirmed wild-type BRAF lesions were included. The participants underwent plasma circulating cell-free DNA and tumor tissue DNA isolation, and both were submitted to using competitive allele-specific TaqMan™ real-time polymerase chain reaction technology mutation detection assays. Sensitivity and specificity measures and positive and negative predictive values were calculated. Twelve patients with conventional ameloblastoma were included. BRAF V600E mutation was detected in 11/12 (91.66%) ameloblastoma tissue samples. However, the mutation was not detected in any of the plasma-based liquid biopsy circulating cell-free DNA samples in both ameloblastomas and negative control group. The sensitivity and specificity of plasma-based liquid biopsy for the detection of the BRAF V600E mutation in circulating cell-free DNA was 0.0 and 1.0, respectively. The agreement between index test and reference standard results was 26.66%. Plasma-based liquid biopsy does not seem to be an accurate method for the detection of the BRAF V600E mutation in circulating circulating cell-free DNA from patients with ameloblastoma, regardless of tumor size, anatomic location, recurrence status, and other clinicopathological features.

Martins-de-Barros AV ，da Costa Araújo FA ，Barros AMI ，Dos Santos EGF ，Barbosa Neto AG ，da Silva HAM ，de Lima ELS ，Muniz MTC ，Neves RFSN ，de Hollanda Valente RO ，de Oliveira E Silva ED ，de Vasconcelos Carvalho M ... -  《-》

Factors affecting the accuracy of anti-BRAF V600E immunohistochemistry results in ameloblastomas.

There are still some controversies about the results of anti-BRAF V600E-specific antibody immunohistochemistry in ameloblastomas. This study aimed to examine the accuracy of V600E-specific antibody immunohistochemistry in detection of BRAF V600E mutation in ameloblastoma tissue sections of different ages. The BRAF V600E status of 64 ameloblastoma specimens was assessed using both Sanger sequencing and V600E-specific antibody immunohistochemistry, and the sensitivity, specificity, positive predictive value, and negative predictive value were calculated. The difference in V600E-specific antibody immunohistochemistry staining intensity among the three groups of ameloblastoma tissue blocks of different ages was evaluated by chi-square test. The consistency between V600E-specific antibody immunohistochemistry and DNA sequencing results and the V600E-specific antibody immunohistochemistry staining intensity of 15 paired newly-cut and 3-month storage sections of the same 15 ameloblastomas were also compared. For detection of BRAF V600E mutation, the V600E-specific antibody immunohistochemistry had high sensitivity (98.21% 55/56), specificity (87.5% 7/8), positive predictive value (98.21% 55/56), and negative predictive value (87.5% 7/8). Heterogeneity of the staining intensity was observed in the same tissue section, but all or none expression pattern was noticed in the solid tumor nests. The storage time of paraffin tissue blocks ranging from 2 to 14 years did not affect the V600E-specific antibody-positive staining intensity. However, the three-month storage sections showed a significant diminishment of V600E-specific antibody-positive staining signals. The BRAF V600E-specific antibody immunohistochemistry is suitable for routine detection of BRAF V600E mutation in ameloblastomas. The all or none expression pattern suggests the BRAF V600E mutation may be an early event in the pathogenesis of ameloblastoma.

Chang JYF ，Lu PH ，Tseng CH ，Wang YP ，Lee JJ ，Chiang CP ... -  《-》

High prevalence of BRAF V600E mutations in Korean patients with ameloblastoma: Clinicopathological significance and correlation with epithelial-mesenchymal transition.

BRAF V600E mutations are activating mutations that have recently been detected in ameloblastoma. However, their prevalence has not been reported in East Asian patients with ameloblastoma and their clinicopathological significance remains unclear. In this study, we examined the prevalence and clinicopathological significance of BRAF V600E mutations in Korean patients with ameloblastoma. In addition, we investigated the relationship between BRAF V600E mutations and epithelial-mesenchymal transition, which has not been studied in ameloblastoma. Thirty ameloblastoma tissue samples were collected, and DNA isolation, polymerase chain reaction, and Sanger sequencing were performed to detect BRAF V600E mutations. Immunohistochemistry was carried out using antibodies against two epithelial-mesenchymal transition-inducing transcription factors, Twist and Snail. Associations of BRAF V600E mutations with clinicopathological factors and expression of Twist and Snail were statistically analyzed. We found a high frequency (90.0%) of BRAF V600E mutations, and mutation status was not associated with clinicopathological factors including age, tumor location, and recurrence. Positive expression of Twist and Snail was observed in 33.3% and 56.7% of cases, respectively, and associated with recurrence (P = 0.020 and 0.010, respectively). There was no correlation between BRAF V600E mutation status and expression of Twist and Snail (P = 1.000, for both). A higher prevalence of BRAF V600E mutations was identified in Korean patients with ameloblastoma compared with previous studies, which indicates that BRAF-targeted therapies can be widely used for refractory ameloblastomas. Furthermore, our findings suggest that BRAF V600E mutations and epithelial-mesenchymal transition may act independently in the development of ameloblastoma.

Oh KY ，Cho SD ，Yoon HJ ，Lee JI ，Ahn SH ，Hong SD ... -  《-》

Frequency of BRAF V600E mutation in a group of Thai patients with ameloblastomas.

BRAF V600E mutation has recently been reported in a high proportion of ameloblastomas. This study was conducted to investigate the frequency of this mutation in ameloblastoma and unicystic ameloblastoma. The correlation between clinicopathologic data and BRAF V600E mutation was also analyzed. A total of 51 archival samples of ameloblastomas and 22 cases of unicystic ameloblastomas were examined for BRAF V600E mutation by using anti-BRAF V600E (clone VE1) immunohistochemistry. Positivity for anti-BRAF V600E antibody was detected in 72.5% (37 of 51) of ameloblastomas, but the mutation showed no significant correlation with the clinicopathologic parameters. With regard to unicystic ameloblastoma, 95.5% (21) of the 22 cases exhibited positive immunostaining for BRAF V600E, whereas only 1 case showed the mural subtype of wild-type BRAF. A high frequency of BRAF V600E mutation was detected in a group of Thai patients with ameloblastomas, suggesting the future use of BRAF-targeted therapy in patients with BRAF-mutated ameloblastoma. However, no significant association between BRAF V600E mutation and the clinicopathologic characteristics of ameloblastomas was found in our study.

Lapthanasupkul P ，Laosuk T ，Ruangvejvorachai P ，Aittiwarapoj A ，Kitkumthorn N ... -  《-》

The diagnostic utility of BRAF VE1 mutation-specific immunohistochemistry in ameloblastoma.

Ameloblastoma is a benign, locally aggressive odontogenic neoplasm with variable solid and cystic morphology. On account of its histologic variety, diagnostically challenging cases can bear resemblance to odontogenic keratocyst/keratocystic odontogenic tumor (KCOT) or dentigerous cyst (DC). BRAFV600E mutation has been reported to be specific for and frequent in ameloblastoma, and this study evaluated the usefulness of immunohistochemistry (IHC) using the BRAF VE1 mutant-specific antibody as a diagnostic adjunct in this setting. We investigated 46 ameloblastomas, 30 KCOTs, and 30 DCs. BRAF VE1 IHC was performed on all cases and allele-specific polymerase chain reaction (AS-PCR) for BRAFV600E mutation was performed on 30 ameloblastomas and any IHC-positive KCOT/DC. BRAF VE1 IHC was positive in 31/37 (83.8%) mandibular ameloblastomas but not in any maxillary ameloblastomas (0/9), KCOT (0/30), or DC (0/30). Equivocal staining was seen in 1/37 (3.3%) mandibular ameloblastomas. Of the 30 ameloblastomas subjected to AS-PCR, BRAFV600E mutation was identified in 19/23 (82.6%) mandibular ameloblastomas and 0/7 (0.0%) maxillary ameloblastomas. BRAFV600E mutant ameloblastomas were positive by IHC in 18/19 (94.7%) cases and equivocal in 1/19 (5.3%) cases. All 11 (100.0%) BRAF-wild type ameloblastomas were negative by IHC. BRAF VE1 is an excellent tool for the diagnosis of mandibular ameloblastoma but of limited utility in the maxilla, where it less commonly occurs and where BRAFV600E mutation is considerably less frequent.

Mendez LD ，Wolsefer NS ，Asa SL ，Wasman J ，Yoest JM ，Stojanov IJ ... -  《-》