BRAF V600E mutational load as a prognosis biomarker in malignant melanoma.

Arrate Sevilla,Isabel Smith,Jesús M Cortés,Ana Sánchez-Diez,Verónica Velasco,Goikoane Cancho-Galan,Maria Dolores Boyano,M Celia Morales,Karmele Mujika,Javier Rasero,Aintzane Asumendi,Cristina Penas,Pilar A Ezkurra,Santos Alonso,Suzie Chen

doi:10.1371/journal.pone.0230136

Abstract

Analyzing the mutational load of driver mutations in melanoma could provide valuable information regarding its progression. We aimed at analyzing the heterogeneity of mutational load of BRAF V600E in biopsies of melanoma patients of different stages, and investigating its potential as a prognosis factor. Mutational load of BRAF V600E was analyzed by digital PCR in 78 biopsies of melanoma patients of different stages and 10 nevi. The BRAF V600E load was compared among biopsies of different stages. Results showed a great variability in the load of V600E (0%-81%). Interestingly, we observed a significant difference in the load of V600E between the early and late melanoma stages, in the sense of an inverse correlation between BRAF V600E mutational load and melanoma progression. In addition, a machine learning approach showed that the mutational load of BRAF V600E could be a good predictor of metastasis in stage II patients. Our results suggest that BRAF V600E is a promising biomarker of prognosis in stage II patients.

Highlights

We have analyzed the mutational load of BRAF V600E in 78 paraffin-embedded skin biopsies from different melanoma stages, based on American Joint Committee on Cancer (AJCC) classification, as well as from 10 nevi
To remove the confounding contribution of surrounding, healthy tissue, the BRAF V600E mutational load corresponding to the tumor tissue was obtained by correcting the obtained value by the proportion of tumor area in each biopsy based on immunohistochemistry (IHC) images obtained with the BRAF V600E antibody VE1 (Fig 1)
BRAF V600E load has been previously analyzed in melanoma samples by dropled digital polymerase chain reaction (PCR) in order to compare its precision with other techniques [6, 17]

Summary

Introduction

In some samples with BRAF V600E mutational load higher than 60%. We have analyzed the mutational load of BRAF V600E in 78 paraffin-embedded skin biopsies from different melanoma stages, based on AJCC classification, as well as from 10 nevi. Results show a great variability in the biopsies regarding their BRAF V600E mutational load, ranging from 0% to 81% (median 1.27%).

Results

Conclusion