[BRAF mutation evolution in melanoma: Myth or reality?]

Area of Science:

• Oncology
• Molecular Biology
• Genetics

Background:

• BRAF mutational status is key for melanoma treatment, particularly with B-Raf inhibitors in metastatic cases.
• Hypotheses on BRAF mutation instability during melanoma progression suggest molecular heterogeneity, potentially explaining treatment discrepancies.
• Understanding BRAF mutation stability is vital for accurate patient stratification and therapeutic management.

Purpose of the Study:

• To retrospectively compare BRAF mutational status in matched primary and metastatic melanoma lesions.
• To evaluate the stability of BRAF mutations throughout melanoma progression.
• To assess the sensitivity of various molecular techniques in detecting BRAF mutations.

Main Methods:

• Analysis of 150 matched melanoma samples (primary and metastatic) from 56 patients.
• Utilized immunohistochemistry (anti-BRAF), PCR-HRM, Sanger sequencing, Next Generation Sequencing (NGS), and digital PCR.
• Investigated seven cases with apparent tumor heterogeneity using techniques of increasing sensitivity.

Main Results:

• Seven cases initially suggested tumor heterogeneity.
• More sensitive techniques identified false-negative results in older methods: 1 for immunohistochemistry, 1 for NGS, and 5 for PCR-HRM Sanger.
• The study demonstrated the stability of BRAF mutations during melanoma progression.

Conclusions:

• BRAF mutations are stable throughout melanoma progression, and apparent heterogeneity often results from the limited sensitivity of older molecular diagnostic methods.
• Immunohistochemistry demonstrates high sensitivity for detecting the common BRAF V600 mutation.
• Accurate BRAF mutational status determination is essential for effective melanoma therapeutic management.