6-[(3-aMinophenyl)Methyl]-4,6-dihydro-4-Methyl-2-(Methylsulfinyl)-5H-Thieno[2',3':4,5]pyrrolo[2,3-d]pyridazin-5-one

Pyruvate kinase catalyzes the final step in glycolysis, the formation of pyruvate and ATP from phosphoenolpyruvate and ADP. The expression of the M₂ isozyme of pyruvate kinase (PKM2) plays an important role in the metabolic reprogramming of tumor cells, which require high amounts of glucose for proliferation. PKM2 is allosterically regulated by the upstream glycolytic intermediate, fructose-1,6-bisphosphate (FBP), which controls glycolysis in a feed forward mechanism. Whereas cancer cells exist in highly phosphorylated states, the binding of certain peptide motifs with phosphorylated tyrosines can inhibit PKM2 activity by causing the release of FBP from the allosteric site. ML-265 activates tumor-specific PKM2 (EC₅₀ = 92 nM) by binding to the dimer-dimer interface between two subunits of PKM2 and inducing tetramerization, which is the most active form of the enzyme. It demonstrates >100-fold selectivity for PKM2 over the related PKM1, PKR, and PKL isoforms. At 50 mg/kg, ML-265 has been shown to reduce tumor size, weight, and occurrence in mice bearing H1299 cell xenografts in a model of human non-small cell lung carcinoma.