Checkmate for CHK2: Discovery of First-in-Class Covalent CHK2 Inhibitors with High Potency and Selectivity
12 affiliations
- 1Department for Medicinal Chemistry, IBE, Faculty of Medicine, University of Tübingen, Auf der Morgenstelle 8, Tübingen, Germany, 72076
- 2Cluster of Excellence iFIT (EXC
- 3Functionally Instructed Tumor Therapies’, University of Tübingen
- 4Department of Pharmaceutical/Medicinal Chemistry, Institute of Pharmaceutical Sciences,Faculty of Sciences, University of Tübingen, Auf der Morgenstelle 8, Tübingen, Germany, 72076
- 5Department for Molecular Design and Pharmaceutical Biophysics, Institute of Pharmaceutical Sciences, Faculty of Sciences, University of Tübingen, Auf der Morgenstelle 8, Tübingen, Germany, 72076
- 6Department for Pharmaceutical (Bio-)analysis, Institute of Pharmaceutical Sciences, Faculty of Sciences, University of Tübingen, Auf der Morgenstelle 8, Tübingen, Germany, 72076
- 7Structural Genomics Consortium, Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue-Straße 15, Frankfurt am Main, Germany, 60438
- 8Institute of Pharmaceutical Chemistry, Buchmann Institute for Molecular Life Sciences, Goethe University Frankfurt, Max-von-Laue-Straße 9, Frankfurt am Main, Germany, 60438
- 9Frankfurt Cancer Institute (FCI) and German Translational Cancer Network (DKTK) Site Frankfurt/Mainz
- 10Tübingen Center for Academic Drug Discovery & Development (TüCAD2
- 11University of Tübingen
- 12Interfaculty Institute for Biomedical Informatics (IBMI, University of Tübingen, Sand 14, Tübingen, Germany, 72076
Abstract
Checkpoint kinase 2 (CHK2), a serine/threonine kinase encoded by CHEK2, plays a key role in the DNA damage response (DDR), acting downstream of ataxia-telangiectasia mutated (ATM) kinase in the ATM–CHK2–p53 signaling axis. Despite considerable interest in CHK2 as a potential therapeutic target, our understanding of its biological functions and therapeutic potential remains constrained by the limited availability of potent and selective chemical probes. While several non-covalent CHK2 inhibitors have been developed, their utility for interrogating CHK2 biology is often limited by suboptimal kinase selectivity. Moreover, selective covalent inhibitors that enable robust and sustained pharmacological perturbation of CHK2 have not been reported. To address this gap, we developed the covalent CHK2 inhibitor (R)-12b, which selectively targets Cys231 at the P3 position of the glycine-rich loop (P-loop). Covalent binding of (R)-12b induces a repositioning of the P-loop, leading to an outward displacement of the N-lobe and expansion of the ATP-binding pocket. (R)-12b exhibits nanomolar biochemical and cellular potency, good in vitro metabolic stability, moderate covalent bond-formation kinetics, and a highly favorable kinome-wide selectivity profile. Together, these properties establish (R)-12b as a first-in-class selective covalent CHK2 inhibitor and a valuable chemical tool for exploring CHK2 biology and further elucidating its therapeutic potential.
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BibTeX
@misc{liang2026checkmate,
title = {{Checkmate for CHK2: Discovery of First-in-Class Covalent CHK2 Inhibitors with High Potency and Selectivity}},
author = {Xiaojun Julia Liang and Janosch Rheinganz and Fabian B. Kraft and Sven R. Aldea and Benedikt Masberg and Alexander Rasch and Martin P. Schwalm and Jason Stahlecker and Janis Leske and Susanne Müller and Stefan Knapp and Stefan Laufer and Michael Lämmerhofer and Frank M. Böckler and Matthias Gehringer},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15009954/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009954/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Checkmate for CHK2: Discovery of First-in-Class Covalent CHK2 Inhibitors with High Potency and Selectivity
AU - Xiaojun Julia Liang
AU - Janosch Rheinganz
AU - Fabian B. Kraft
AU - Sven R. Aldea
AU - Benedikt Masberg
AU - Alexander Rasch
AU - Martin P. Schwalm
AU - Jason Stahlecker
AU - Janis Leske
AU - Susanne Müller
AU - Stefan Knapp
AU - Stefan Laufer
AU - Michael Lämmerhofer
AU - Frank M. Böckler
AU - Matthias Gehringer
PY - 2026
DA - 2026/10/05
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009954/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009954/v1
AB - Checkpoint kinase 2 (CHK2), a serine/threonine kinase encoded by CHEK2, plays a key role in the DNA damage response (DDR), acting downstream of ataxia-telangiectasia mutated (ATM) kinase in the ATM–CHK2–p53 signaling axis. Despite considerable interest in CHK2 as a potential therapeutic target, our understanding of its biological functions and therapeutic potential remains constrained by the limited availability of potent and selective chemical probes. While several non-covalent CHK2 inhibitors have been developed, their utility for interrogating CHK2 biology is often limited by suboptimal kinase selectivity. Moreover, selective covalent inhibitors that enable robust and sustained pharmacological perturbation of CHK2 have not been reported. To address this gap, we developed the covalent CHK2 inhibitor (R)-12b, which selectively targets Cys231 at the P3 position of the glycine-rich loop (P-loop). Covalent binding of (R)-12b induces a repositioning of the P-loop, leading to an outward displacement of the N-lobe and expansion of the ATP-binding pocket. (R)-12b exhibits nanomolar biochemical and cellular potency, good in vitro metabolic stability, moderate covalent bond-formation kinetics, and a highly favorable kinome-wide selectivity profile. Together, these properties establish (R)-12b as a first-in-class selective covalent CHK2 inhibitor and a valuable chemical tool for exploring CHK2 biology and further elucidating its therapeutic potential.
ER -