When a Lead is a Lead

As we keep on saying, epigenetics is big.  So, today we present another paper on an old friend, BRD4.  This paper is a follow up from previous work where they used docking and X-ray to find the thiazolidinone fragment hit that was elaborated as shown below (Figure 1), but with potency in the single digit micromolar in vitro and double digit in cellulo. 

Figure 1.  Previous work from these authors.

In this work, they continue developing this scaffold investigating the reversed sulfonamide(Figure 2)

Figure 2.  Reversed Sulfonamide

which had significantly improved activity.  Cyclo-aliphatic rings showed increases in potency, but with larger rings also decreasing ligand efficiency.  Aromatic rings decreased potency and larger groups (rings with linkers) were not tolerated at all.  

The crystal structure of the cyclopentyl derivative was solved and was seen to have a different binding mode from the original fragment.  In this case, the WPF shelf is NOT the major binding site for the compound.  In the end, they ended up with

Figure 3.  End Result of this study.  

This is compound is potent (albeit not super potent), ligand efficient, with cell-based activity,  selectivity, and good PK properties.   What I really like is that final sentence of the conclusion:

a promising BRD4inhibitor and a useful lead for further anticancer drug development.