Discovery of Potent and Selective Inhibitors for ADAMTS-4 through DNA-Encoded Library Technology (ELT)

Abstract

The aggrecan degrading metalloprotease ADAMTS-4 has been identified as a novel therapeutic target for osteoarthritis. Here, we use DNA-encoded Library Technology (ELT) to identify novel ADAMTS-4 inhibitors from a DNA-encoded triazine library by affinity selection. Structure-activity relationship studies based on the selection information led to the identification of potent and highly selective inhibitors. For example, 4-(((4-(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)-6-(((4-methylpiperazin-1-yl)methyl)amino)-1,3,5-triazin-2-yl)amino)methyl)-N-ethyl-N-(m-tolyl)benzamide has IC50 of 10 nM against ADAMTS-4, with >1000-fold selectivity over ADAMT-5, MMP-13, TACE, and ADAMTS-13. These inhibitors have no obvious zinc ligand functionality.

Keywords: ADAMTS-4; DNA-encoded library; inhibitors.

Figure 1

Selection of library against ADAMTS-4. (a) The triazine library. (b) The cube corresponding to 4-(aminomethyl)benzoic acid as cycle 2 is shown in detail. The copy number of the selected species is indicated by the continuous color and size of the points (darker and bigger points indicate higher copy number). The structure shown at the bottom represents the family of compounds defined by a line along the BB1 axis (arrow).

Scheme 1. Synthesis of ADAMTS-4 Off-DNA Hits

Reagents and conditions: (i) amine (1 equiv), EDCI (1.25 equiv), DMAP (0.2 equiv), CH₂Cl₂, 0 °C – rt; (ii) TFA (50% in CH₂Cl₂), room temperature, 20 min; (iii) amine (1 equiv), CH₃CN/H₂O (1/1), pH 9–10, 0 °C; (iv) amine (R²NH₂ or R³) (1 equiv), CH₃CN/H₂O (1/1), pH 9–10, room temperature overnight; (v) R³ = H: Pd/C, H₂, room temperature 1 h; R³ = OH/HCl (6 N, 10% v/v), CH₃CN/H₂O (1/1), 80 °C overnight; R³ = amines/amine (5–10 equiv), CH₃CN/H₂O (1/1), 80 °C; (vi) amine (1 equiv), DIEA (2.5 equiv), NMP, 0 °C; (vii) amine (5 equiv), NMP, 80 °C for 1 h; (viii) 1 N NaOH, room temperature overnight.