N-(7-Cyano-6-(4-fluoro-3-(2-(3-(trifluoromethyl)phenyl)acetamido)phenoxy)benzo[d]thiazol-2-yl)cyclopropanecarboxamide (TAK632) Promotes Inhibition of BRAF through the Induction of Inhibited Dimers

J Med Chem. 2018 Jun 14;61(11):5034-5046. doi: 10.1021/acs.jmedchem.8b00499. Epub 2018 May 18.

Abstract

BRAFV600E is the most common activating mutation in melanoma and patients treated with BRAFV600E inhibitors all develop resistance within one year. A significant resistance pathway is paradoxical activation (transactivation) involving BRAF dimers, whereby an inhibitor bound protein subunit allosterically activates the other subunit. We recently reported on dimeric BRAFV600E -selective vemurafenib inhibitors that stabilize an inactive αC-out/αC-out homodimeric conformation with improved inhibitor potency and selectivity in vitro. We set out to extend this strategy to target RAF homo- and heterodimers with the pan-RAF inhibitor TAK632 in dimeric configuration. Surprisingly, we find that monomeric TAK632 induces an active αC-in/αC-in BRAF dimer conformation, while dimeric TAK inhibitors cannot promote BRAF dimers and have significantly compromised potency in vitro. These studies uncover the intimate connection between BRAF dimerization and TAK632 mode of inhibition and highlight the importance of understanding the impact of BRAF inhibitors on kinase dimerization.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzothiazoles / chemistry*
  • Benzothiazoles / pharmacology*
  • Cell Line, Tumor
  • Dimerization
  • Drug Design
  • Humans
  • MAP Kinase Signaling System / drug effects
  • Models, Molecular
  • Nitriles / chemistry*
  • Nitriles / pharmacology*
  • Protein Kinase Inhibitors / chemistry*
  • Protein Kinase Inhibitors / pharmacology*
  • Protein Multimerization / drug effects*
  • Protein Structure, Quaternary
  • Proto-Oncogene Proteins B-raf / antagonists & inhibitors*
  • Proto-Oncogene Proteins B-raf / chemistry*

Substances

  • Benzothiazoles
  • Nitriles
  • Protein Kinase Inhibitors
  • TAK-632
  • Proto-Oncogene Proteins B-raf