Cell experiment:

PF-06726304 dilutions are prepared. Karpas-422 cells are treated with PF-06726304. Cell Growth Inhibition is performed and IC50 values are calculated[1].

Animal experiment:

Mice: Mice are treated with PF-06726304 at 200 and 300 mg/kg BID for 20 days. Tumor growth is monitored for several weeks following cessation of dosing. Average body weight is measured during the duration of compound treatment. Global H3K27Me3 levels are measured in Karpas-422 tumors harvested on day 20[1].

PF-06726304 is a potent and selective EZH2 inhibitor with a Ki of 0.7 nM.

PF-06726304 displays potent biochemical and cellular potencies in the Karpas-422 cell line. Upon treatment with PF-06726304 for 7 days, both TNFRSF21 and PRDM1 are upregulated in Karpas-422 cells containing both wild-type and Y641N mutant EZH2 proteins in a dose-dependent manner[1].

PF-06726304 inhibits tumor growth and induces robust modulation of downstream biomarkers in a Karpas-422 in vivo model. Treatment with PF-06726304 is well-tolerated at 200 and 300 mg/kg in mice, with less than 10% body weight loss observed during the course of the experiment. on day 20, PF-06726304 demonstrates tumor stasis and regression at the 200 and 300 mg/kg dose levels, respectively. In addition, tumor growth inhibition is sustained for at least another 3 weeks after the last dose, demonstrating the ability of PF-06726304 to mediate long-term epigenetic reprogramming in cells. PF-06726304 induces approximately 55.5% and 66.4% reduction of the H3K27Me3 level at doses of 200 and 300 mg/kg, respectively. In addition, the PRC2 target genes TNFRSF21 and PRDM1 are both strongly upregulated in both the 200 and 300 mg/kg dosing arms[1].

[1]. Kung PP, et al. Design and Synthesis of Pyridone-Containing 3,4-Dihydroisoquinoline-1(2H)-ones as a Novel Class of Enhancer of Zeste Homolog 2 (EZH2) Inhibitors. J Med Chem. 2016 Sep 22;59(18):8306-25.