Challenges and opportunities in targeting the menin–MLL interaction

Menin is an essential co-factor of oncogenic MLL fusion proteins and the menin–MLL interaction is critical for development of acute leukemia in vivo. Targeting the menin–MLL interaction with small molecules represents an attractive strategy to develop new anticancer agents. Recent developments, including determination of menin crystal structure and development of potent small molecule and peptidomimetic inhibitors, demonstrate the feasibility of targeting the menin–MLL interaction. On the other hand, biochemical and structural studies revealed that MLL binds to menin in a complex bivalent mode engaging two MLL motifs, and therefore inhibition of this protein–protein interaction represents a challenge. This review summarizes the most recent achievements in targeting the menin–MLL interaction as well as discusses potential benefits of blocking menin in cancer.