Synthesis of Small Molecule Inhibitors of the Mixed Lineage Leukemia 1 DNA Binding Interaction

The KMT2A gene encodes the protein mixed lineage leukemia 1 (MLL1), a histone methyltransferase which plays a regulatory role in embryonic development and hematopoiesis. KMT2A can undergo translocations with over 70 different fusion partners, resulting in the production of oncogenic chimeric proteins which are observed in approximately 10% of all leukemias. The oncogenic activity of these proteins is dependent upon the ability of the proteins to bind to DNA through a CXXC DNA binding domain retained from MLL1. Because of their roles in leukemias, MLL1 fusion proteins are therapeutic targets for the treatment of these cancers. In this project, a lead compound designed to disrupt an MLL1 DNA binding interaction was optimized. Using standard synthetic organic chemistry techniques, 11 analogs of the lead compound were synthesized, and these compounds were tested both for their ability to inhibit binding of the MLL1 CXXC domain to DNA as well as for their ability to inhibit the growth of leukemia cell lines harboring MLL fusions. The IC¬50 (inhibitory concentration for 50% inhibition) values of the synthesized analogs ranged from 2.3 μM to 215 μM, with the most potent analog being 6-fold more potent than the lead compound. Efficacy in inhibiting the growth of leukemia cell lines was improved by substituting a carboxylate moiety with an ethyl ester, likely due to improved cellular permeability. Future efforts will be directed towards further optimization of the potency of the inhibitors.