RO5126766 is a potent and selective dual inhibitor of MEK and RAF kinases, which are key components of the MAPK signaling pathway. This pathway is frequently dysregulated in various cancers, especially those with mutations in BRAF or RAS genes. The compound has been investigated for its potential in treating solid tumors, including melanoma, non-small cell lung cancer, and colorectal cancer, where aberrant MAPK signaling drives tumor growth and survival. By simultaneously inhibiting both MEK and RAF, RO5126766 helps overcome resistance mechanisms that often develop with single-pathway inhibitors. This dual inhibition leads to more effective suppression of ERK activation, resulting in reduced cancer cell proliferation and induction of apoptosis. RO5126766 has shown promising activity in preclinical models, particularly in tumors with acquired resistance to first-generation BRAF inhibitors. Its development supports a strategy for targeting pathway reactivation in resistant cancers, making it a candidate for use in combination therapies or as a second-line treatment in targeted oncology.