In our effort to discover new Autotaxin (ATX) inhibitors we have previously identified various hits [Pubmed] that led to six Industrial Property Organization (IPO) patents GR1010099, GR1010098, GR1010104, GR1010103, GR1010097, GR1010096. This effort was followed by a hit-to-lead potency optimization process employing Structure-Activity Relationship studies culminating in the finding of two new ATX inhibitors (with an active IPO patent GR1010268 and a Patent Cooperation Treaty (PCT) application WO 2022/003377 A1) now being at the stage of lead optimization [Pubmed].

Autotaxin (ATX) is a secreted enzyme, widely present in biological fluids. Increased ATX expression is detected in different chronic inflammatory diseases, while ATX has been established as a promising therapeutic target for several conditions. In the hope of identifying novel ATX inhibitor series, chemoinformatic tools were used in a previous study where 14,000 pure diverse small molecules included in the Hitfinder database were virtually screened with ATX. This effort led to the identification of 6 new structural ATX “hits” for further development. Herein, we describe the potency optimization for one of these identified “hits” (SC-49) through exploration of Structure-Activity Relationships (SAR) and isosterism studies. This involved three rounds of SAR studies on three different positions of SC-49. All analogues designed and synthesized for the SAR studies were evaluated for their inhibitory activity against ATX using the Amplex red assay, which led to the identification of two promising derivatives with an IC50 at the lower micromolar range. Further experimentation rendered these two new compounds as non-toxic chemical scaffolds for further optimization, while, based on cell-based assays, both our compounds were found to significantly inhibit the cell motility of cancer lung epithelial cells. By combining molecular dynamics simulation and mode of inhibition experimental results, it can be proposed that the compounds of this series bind to the hydrophobic cavity of the catalytic site of ATX at a location distinct from the primary substrate (LPC) binding site, but in a way where both substrate binding and catalysis are affected.