SP2509 is a novel histone demethylase LSD1 (KDM1A) antagonist with IC50 of 13 nM; no inhibition on MAO-A and MAO-B.

SP2509 attenuated the binding of LSD1 with the corepressor CoREST, increased the permissive H3K4Me3 mark on the target gene promoters, and increased the levels of p21, p27 and CCAAT/enhancer binding protein α in cultured AML cells. In addition, SP2509 treatment or LSD1 shRNA inhibited the colony growth of AML cells. SP2509 also induced morphological features of differentiation in the cultured and primary AML blasts. SP2509 induced more apoptosis of AML cells expressing mutant NPM1 than mixed-lineage leukemia fusion oncoproteins.

Treatment with SP2509 alone significantly improved the survival of immune-depleted mice following tail-vein infusion and engraftment of cultured or primary human AML cells. Co-treatment with pan-HDAC inhibitor (HDI) panobinostat (PS) and SP2509 was synergistically lethal against cultured and primary AML blasts. Compared with each agent alone, co-treatment with SP2509 and PS significantly improved the survival of the mice engrafted with the human AML cells, without exhibiting any toxicity.