RAF isoform selectivity of MEK inhibitors and rational design of a covalent ARAF-MEK inhibitor
5 affiliations
- 1Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
- 2Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
- 3Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA.
- 4Department of Medicine, Harvard Medical School, Boston, MA 02115, USA.
- 5Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA.
Abstract
Aberrant activation of the RAS/RAF/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase pathway is a frequent cause of cancer. Allosteric MEK inhibitors block this pathway by binding RAF-MEK complexes to prevent activation of MEK by RAF. However, how MEK inhibitor potency varies across the three RAF isoforms remains poorly understood. We profiled seven allosteric MEK inhibitors and observed a notable hierarchy of sensitivity: All most potently inhibited CRAF-driven MEK activation while relatively sparing ARAF-driven activation. We identified point mutations in ARAF and CRAF proximate to the MEK inhibitor binding site that markedly altered inhibitor sensitivity. Using a rational design approach, we developed a more potent inhibitor of ARAF-driven MEK signaling, TWG-07-148. Our cryo-electron microscopy structure shows how this acrylamide-containing analog of MEK inhibitor trametinib covalently targets Cys⁵¹⁴, a residue unique to ARAF. Our studies highlight the importance of the activating RAF isoform as a determinant of MEK inhibitor sensitivity and provide proof of concept for the development of MEK inhibitors that more effectively block ARAF-driven MEK signaling via covalent targeting of Cys⁵¹⁴.
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BibTeX
@article{chakraborty2026isoform,
title = {{RAF isoform selectivity of MEK inhibitors and rational design of a covalent ARAF-MEK inhibitor}},
author = {Sayan Chakraborty and Jie Jiang and Javier Vinals Camallonga and Dimitris Gazgalis and Thomas W. Gero and Maurício T. Tavares and Georgia Dittemore and Emre Tkacik and Tyler S. Beyett and Dong Man Jang and Byung Hak Ha and Felix H. Gottlieb and Talya Levitz and Rebecca J. Metivier and Anna M. Schmoker and David A. Scott and Hyesung Jeon and Pasi A. Jänne and Michael J. Eck},
journal = {Science Advances},
year = {2026},
month = oct,
doi = {10.1126/sciadv.aee5241},
url = {https://www.science.org/doi/10.1126/sciadv.aee5241},
note = {CC BY},
}
RIS
TY - JOUR
TI - RAF isoform selectivity of MEK inhibitors and rational design of a covalent ARAF-MEK inhibitor
AU - Sayan Chakraborty
AU - Jie Jiang
AU - Javier Vinals Camallonga
AU - Dimitris Gazgalis
AU - Thomas W. Gero
AU - Maurício T. Tavares
AU - Georgia Dittemore
AU - Emre Tkacik
AU - Tyler S. Beyett
AU - Dong Man Jang
AU - Byung Hak Ha
AU - Felix H. Gottlieb
AU - Talya Levitz
AU - Rebecca J. Metivier
AU - Anna M. Schmoker
AU - David A. Scott
AU - Hyesung Jeon
AU - Pasi A. Jänne
AU - Michael J. Eck
PY - 2026
DA - 2026/10/23
JO - Science Advances
DO - 10.1126/sciadv.aee5241
UR - https://www.science.org/doi/10.1126/sciadv.aee5241
AB - Aberrant activation of the RAS/RAF/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase pathway is a frequent cause of cancer. Allosteric MEK inhibitors block this pathway by binding RAF-MEK complexes to prevent activation of MEK by RAF. However, how MEK inhibitor potency varies across the three RAF isoforms remains poorly understood. We profiled seven allosteric MEK inhibitors and observed a notable hierarchy of sensitivity: All most potently inhibited CRAF-driven MEK activation while relatively sparing ARAF-driven activation. We identified point mutations in ARAF and CRAF proximate to the MEK inhibitor binding site that markedly altered inhibitor sensitivity. Using a rational design approach, we developed a more potent inhibitor of ARAF-driven MEK signaling, TWG-07-148. Our cryo-electron microscopy structure shows how this acrylamide-containing analog of MEK inhibitor trametinib covalently targets Cys⁵¹⁴, a residue unique to ARAF. Our studies highlight the importance of the activating RAF isoform as a determinant of MEK inhibitor sensitivity and provide proof of concept for the development of MEK inhibitors that more effectively block ARAF-driven MEK signaling via covalent targeting of Cys⁵¹⁴.
SN - 2375-2548
ER -