Preclinical Lead Optimization of a 1,2,4-Triazole Based Tankyrase Inhibitor

Abstract

Tankyrases 1 and 2 are central biotargets in the WNT/β-catenin signaling and Hippo signaling pathways. We have previously developed tankyrase inhibitors bearing a 1,2,4-triazole moiety and binding predominantly to the adenosine binding site of the tankyrase catalytic domain. Here we describe a systematic structure-guided lead optimization approach of these tankyrase inhibitors. The central 1,2,4-triazole template and trans- cyclobutyl linker of the lead compound 1 were left unchanged, while side-group East, West, and South moieties were altered by introducing different building blocks defined as point mutations. The systematic study provided a novel series of compounds reaching picomolar IC 50 inhibition in WNT/β - catenin signaling cellular reporter assay. The novel optimized lead 13 resolves previous atropisomerism, solubility, and Caco-2 efflux liabilities. 13 shows a favorable ADME profile, including improved Caco-2 permeability and oral bioavailability in mice, and exhibits antiproliferative efficacy in the colon cancer cell line COLO 320DM in vitro.

A Small-Molecule Tankyrase Inhibitor Reduces Glioma Stem Cell Proliferation and Sphere Formation

“…A weakness of this study is that it is entirely based on in vitro data, so it is not directly translatable to the in vivo setting. We are currently developing and testing G007-LK analogs with enhanced bioavailability that are showing promising properties compatible with blood-brain barrier penetration [64]. Upon the successful validation of transport across the blood-brain barrier in vivo, we will initiate follow-up experiments against GBM in mouse models.…”

Identification of response signatures for tankyrase inhibitor treatment in tumor cell lines

“…Multiple potent small-molecules have been developed to target the catalytic site of TNKS1/2 (Bregman et al, 2013;Huang et al, 2009;Johannes et al, 2015;Mizutani et al, 2018;Shultz et al, 2013;Voronkov et al, 2013;Waaler et al, 2020a). Among these, the triazole-based series including JW74 (Waaler et al, 2011), G007-LK (Voronkov et al, 2013), OD336 (compound 16) (Anumala et al, 2017), and OM-1700 (compound 13) (Waaler et al, 2020a) target the adenosine binding pocket of the TNKS1/2 catalytic domain with high selectivity, whereby G007-LK shows a favorable pharmacokinetic profile in mice (Voronkov et al, 2013). In contrast, agents like XAV939, that bind to the nicotinamide binding pocket of the catalytic domain, are less selective in that they also inhibit additional PARP family members (Haikarainen et al, 2014;Huang et al, 2009).…”

“…Clinical tankyrase inhibitor development has so far been hampered by concerns over intestinal toxicity and other on-target or signaling-pathway-specific side effects (Fujita et al, 2018;Lau et al, 2013;Zhong et al, 2016aZhong et al, , 2016b. Although current preclinical stage tankyrase-specific inhibitors, including G007-LK, do not display the chemical properties required for approval for human testing (Voronkov et al, 2013), research to develop additional TNKS1/2 inhibitors for clinical use is actively pursued (Ferri et al, 2017;Waaler et al, 2020a).…”

The zinc-binding motif in tankyrases is required for the structural integrity and proper function of the catalytic domain

“…A different crystal system with TNKS2 can be achieved when cocrystallizing it with inhibitors binding to the adenosine sub-pocket. 38,39 Treatment with H2O2 of TNKS2 crystals that were co-crystallized with our previously reported TNKS inhibitor OM-1700 did not significantly lower diffraction quality. While lower concentrations of H2O2 showed only partial loss of the zinc-ion, incubation of the crystals with 25 mM H2O2 for 48 hours showed complete loss of electron density corresponding to the zinc ion in the crystal structure.…”