LXH254, a Potent and Selective ARAF-Sparing Inhibitor of BRAF and CRAF for the Treatment of MAPK-Driven Tumors.

Abstract

PURPOSE:

Targeting RAF for antitumor therapy in RAS-mutant tumors holds promise. Herein, we describe in detail novel properties of the type II RAF inhibitor, LXH254.

EXPERIMENTAL DESIGN:

LXH254 was profiled in biochemical, in vitro, and in vivo assays, including examining the activities of the drug in a large panel of cancer-derived cell lines and a comprehensive set of in vivo models. In addition, activity of LXH254 was assessed in cells where different sets of RAF paralogs were ablated, or that expressed kinase-impaired and dimer-deficient variants of ARAF.

RESULTS:

We describe an unexpected paralog selectivity of LXH254, which is able to potently inhibit BRAF and CRAF, but has less activity against ARAF. LXH254 was active in models harboring BRAF alterations, including atypical BRAF alterations coexpressed with mutant K/NRAS, and NRAS mutants, but had only modest activity in KRAS mutants. In RAS-mutant lines, loss of ARAF, but not BRAF or CRAF, sensitized cells to LXH254. ARAF-mediated resistance to LXH254 required both kinase function and dimerization. Higher concentrations of LXH254 were required to inhibit signaling in RAS-mutant cells expressing only ARAF relative to BRAF or CRAF. Moreover, specifically in cells expressing only ARAF, LXH254 caused paradoxical activation of MAPK signaling in a manner similar to dabrafenib. Finally, in vivo, LXH254 drove complete regressions of isogenic variants of RAS-mutant cells lacking ARAF expression, while parental lines were only modestly sensitive.

CONCLUSIONS:

LXH254 is a novel RAF inhibitor, which is able to inhibit dimerized BRAF and CRAF, as well as monomeric BRAF, while largely sparing ARAF.

• Authors: Kelli-Ann Monaco, Scott Delach, Jing Yuan, Yuji Mishina, Paul Fordjour, Emma Labrot, Daniel McKay, Ribo Guo, Stacy Higgins, Hui Qin Wang, Jinsheng Liang, Karen Bui, John Green, Peter Aspesi, Jessi Ambrose, Felipa Mapa, Lesley Griner, Mariela Jaskelioff, John Fuller, Kenneth Crawford, Gwynn Pardee, Stephania Widger, Peter S Hammerman, Jeffrey A Engelman, Darrin D Stuart, Vesselina G Cooke, Giordano Caponigro
• Journal: Clinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 27 Issue 7 Pg. 2061-2073 (04 01 2021) ISSN: 1557-3265 [Electronic] United States
• PMID: 33355204 (Publication Type: Journal Article)
• Copyright: ©2020 American Association for Cancer Research.

Chemical References

• KRAS protein, human
• Protein Kinase Inhibitors
• Proto-Oncogene Proteins B-raf
• Proto-Oncogene Proteins c-raf
• Extracellular Signal-Regulated MAP Kinases
• Proto-Oncogene Proteins p21(ras)

Topics

• Animals
• Extracellular Signal-Regulated MAP Kinases (metabolism)
• Female
• HCT116 Cells
• Humans
• MAP Kinase Signaling System (physiology)
• Mice
• Mutation
• Neoplasms (drug therapy, genetics)
• Protein Kinase Inhibitors (pharmacology, therapeutic use)
• Protein Multimerization
• Proto-Oncogene Proteins B-raf (antagonists & inhibitors, chemistry)
• Proto-Oncogene Proteins c-raf (antagonists & inhibitors, chemistry)
• Proto-Oncogene Proteins p21(ras) (genetics)