Pan-RAF (ARAF/BRAF/CRAF) and MEK

Class

Pan-RAF/MEK molecular glue inhibitor (CNS-penetrant)

Pathway

RAS-RAF-MEK-ERK (MAPK) pathway inhibition by stabilizing an inactive RAF-MEK complex, blocking RAF dimerization-driven signaling

The MAPK pathway (RAS-RAF-MEK-ERK) is a chain of signaling proteins that carries growth signals from receptors on the cell surface into the nucleus, instructing cells to divide. In many cancers, mutations in RAS or in the RAF kinases (ARAF, BRAF, CRAF) keep this chain switched on continuously, driving uncontrolled proliferation. This mechanism uses a molecular glue, a small molecule that binds RAF and MEK together, locking them into a stable, inactive pair rather than blocking either protein alone. Because RAF kinases normally activate one another by physically pairing up (dimerizing), inhibitors that only target one RAF isoform or one activation state can be bypassed when tumor cells assemble alternative dimers or lean on other RAF isoforms. A pan-RAF/MEK glue addresses all three RAF isoforms and their dimer combinations at once, aiming for more complete and durable suppression of the pathway. Its ability to cross into the central nervous system extends this approach to brain tumors and brain metastases, settings where many pathway inhibitors fail to achieve adequate exposure. Broadly, this mechanism is relevant to cancers driven by RAS or RAF pathway alterations, including those that have escaped more narrowly targeted MAPK-pathway drugs.