BRAF Mutation in Cancer
OncogeneB-Raf Proto-Oncogene
BRAF is a serine/threonine kinase in the MAPK signaling pathway. The V600E mutation is the most common, found in melanoma, thyroid, and colorectal cancers. BRAF inhibitors are approved targeted therapies.
What Is BRAF?
BRAF (B-Raf Proto-Oncogene) is a serine/threonine kinase that sits in the RAS/RAF/MEK/ERK (MAPK) signaling cascade, directly downstream of RAS. When activated, BRAF phosphorylates MEK, which in turn activates ERK to promote cell growth, survival, and differentiation. Oncogenic mutations in BRAF constitutively activate this pathway independent of upstream RAS signaling.
BRAF V600E and Beyond
The BRAF V600E mutation accounts for ~90% of all BRAF mutations in cancer. It results in a 500-fold increase in kinase activity compared to wild-type BRAF. Other clinically relevant mutations include V600K (common in melanoma), class II mutations (K601E, which signals as a RAS-independent dimer), and class III mutations (which paradoxically amplify RAS-dependent signaling). BRAF mutations are found in ~50% of melanomas, ~60% of thyroid papillary carcinomas, ~10% of colorectal cancers, and subsets of lung, ovarian, and brain tumors.
Targeted Therapy
BRAF V600E is one of the most successfully drugged oncogenic mutations. BRAF inhibitors (vemurafenib, dabrafenib) combined with MEK inhibitors (trametinib, cobimetinib) are standard of care in BRAF V600-mutant melanoma, and encorafenib plus cetuximab is approved for BRAF V600E-mutant colorectal cancer. However, resistance invariably develops, driven by MAPK pathway reactivation, PI3K/AKT activation, or tumor microenvironment changes.
Morphological Signatures
BRAF-mutant tumors often display distinct histological features. In melanoma, BRAF V600E-mutant tumors tend to show nesting patterns and greater intraepidermal spread. In colorectal cancer, BRAF mutations associate with right-sided location, mucinous histology, and serrated morphology. HistoAtlas quantifies these morphological differences across cancer types using computational histomics from whole slide images.
Frequently Asked Questions
What is a BRAF mutation?
A BRAF mutation is a change in the BRAF gene that causes the BRAF protein kinase to be constitutively active, continuously stimulating cell growth through the MAPK pathway. The most common BRAF mutation is V600E, found in about 50% of melanomas and subsets of thyroid, colorectal, and other cancers.
What does BRAF V600E positive mean?
BRAF V600E positive means the tumor carries a specific mutation where the amino acid valine (V) at position 600 is replaced by glutamic acid (E). This mutation is clinically important because it makes the tumor eligible for targeted therapy with BRAF and MEK inhibitors.
How is BRAF mutation treated?
BRAF V600-mutant cancers are treated with BRAF inhibitors (vemurafenib, dabrafenib, encorafenib), usually combined with MEK inhibitors (trametinib, cobimetinib, binimetinib) to prevent resistance. In melanoma, this combination is standard first-line therapy for BRAF-mutant tumors alongside immunotherapy.