RAF inhibitors that evade paradoxical MAPK pathway activation

Zhang, Chao; Spevak, Wayne; Zhang, Ying; Burton, Elizabeth A.; Ma, Yan; Habets, Gaston; Zhang, Jiazhong; Lin, Jack; Ewing, Todd; Matusow, Bernice; Tsang, Garson; Marimuthu, A.; Cho, Hanna; Wu, Guoxian; Wang, Weiru; Fong, Daniel W.; Nguyen, Hoa; Shi, Songyuan; Womack, Patrick; Nespi, Marika; Shellooe, Rafe; Carias, Heidi; Powell, Ben; Light, Emily; Sanftner, Laura; Walters, Jason; Tsai, James; West, Brian L.; Visor, Gary C.; Rezaei, Hamid; Lin, Paul S.; Nolop, K. B.; Hirth, Peter; Bollag, Gideon

doi:10.1038/nature14982

Cited by 330 publications

(338 citation statements)

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“…In cells with BRAF WT they paradoxically activate RAF and ERK signaling, via a RASdependent mechanism that remains incompletely understood. Recently, a number of RAF inhibitors with diverse structural and biochemical properties entered preclinical and clinical development Peng et al, 2015;Zhang et al, 2015). We sought to develop an integrated model of RAF inhibitor action that would explain the biochemical effects of RAF inhibitors based on their structural properties in any cellular context.…”

Section: Introductionmentioning

confidence: 99%

An Integrated Model of RAF Inhibitor Action Predicts Inhibitor Activity against Oncogenic BRAF Signaling

Karoulia¹,

Wu²,

Ahmed³

et al. 2016

Cancer Cell

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127

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SUMMARYThe complex biochemical effects of RAF inhibitors account for both the effectiveness and mechanisms of resistance to these drugs, but a unified mechanistic model has been lacking. HereCorrespondence and requests for materials should be addressed to: Poulikos.poulikakos@mssm.edu or evripidis.gavathiotis@einstein.yu.edu. * These authors contributed equally to this work Accession numbers. Structural coordinates and parameters have been submitted to the Protein Database Bank under the following accession codes: 4RZV for BRAF R509H /VEM, 4RZW for BRAF R509H /AZ and 5ITA for BRAF WT /AZ-VEM. Other structural coordinates used in this study are the following: PDB ID: 4KSP for TAK bound to BRAF dimer, PDB ID: 3OG7 for VEM bound to BRAF V600E dimer, PDB ID: 4MNF for GDC bound to BRAF V600E dimer, PDB ID: 2FB8 for SB bound to BRAF dimer, PDB ID: 4XV2 for DAB bound to BRAF V600E dimer and PDB ID: 4XV1 for PB bound to BRAF V600E dimer and PDB 4MNE for the BRAF/MEK complex. AUTHOR CONTRIBUTIONSP.I.P., E.G., C.K., M.H., A.L., Z.K., Y.W. and T.A.A designed experiments. Z.K., T.A.A conducted biochemical and cellular studies. E.G., Y.W. performed structural determination and structural analysis. X.W. generated the CRAF-V5 CRISPR cell line. Q.X. synthesized the AZ-VEM compound. C.K., M.H., J.A.F., A.L., E.G., P.I.P. designed animal studies. Z.K., T.A.A and J.B. conducted animal experiments. C.Z. and G.B. provided reagents and analyzed data. P.I.P. and E.G. designed research, analyzed data and wrote the manuscript, which was edited by all authors.C.Z. and G.B. are employees of Plexxikon Inc. All other authors declare no competing financial interests.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. we show that RAF inhibitors exert their effects via two distinct allosteric mechanisms. Drug resistance due to dimerization is determined by the position of the αC-helix stabilized by inhibitor, whereas inhibitor-induced RAF priming and dimerization are the result of inhibitor-induced formation of the RAF/RAS-GTP complex. The biochemical effect of RAF inhibitor in cells is the combined outcome of the two mechanisms. Therapeutic strategies including αC-helix-IN inhibitors are more effective in multiple mutant BRAF-driven tumor models, including colorectal and thyroid BRAF V600E cancers, in which first generation RAF inhibitors have been ineffective. HHS Public Access

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Section: Introductionmentioning

confidence: 99%

An Integrated Model of RAF Inhibitor Action Predicts Inhibitor Activity against Oncogenic BRAF Signaling

Karoulia¹,

Wu²,

Ahmed³

et al. 2016

Cancer Cell

Self Cite

127

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“…Recently, next-generation RAF inhibitors that evade MAPK pathway reactivation were developed as an alternative strategy to potentiate the suppression of MAPK pathway output in BRAF V600E -driven cancers (28,29). These RAF inhibitors, such as PLX8394, were shown to be effective in BRAF V600E and RASmutant melanoma and colorectal cancer cells (28).…”

Section: G466vmentioning

confidence: 99%

“…These RAF inhibitors, such as PLX8394, were shown to be effective in BRAF V600E and RASmutant melanoma and colorectal cancer cells (28). Unlike melanoma, however, non-V600 BRAF mutant alleles comprise a significant proportion (∼40%) of mutations in LA (30)(31)(32).…”

Section: G466vmentioning

confidence: 99%

Preclinical efficacy of a RAF inhibitor that evades paradoxical MAPK pathway activation in protein kinase BRAF -mutant lung cancer

Okimoto

Olivas

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Oncogenic activation of protein kinase BRAF drives tumor growth by promoting mitogen-activated protein kinase (MAPK) pathway signaling. Because oncogenic mutations in BRAF occur in ∼2-7% of lung adenocarcinoma (LA), BRAF-mutant LA is the most frequent cause of BRAF-mutant cancer mortality worldwide. Whereas most tumor types harbor predominantly the BRAF V600E -mutant allele, the spectrum of BRAF mutations in LA includes BRAF V600E (∼60% of cases) and non-V600E mutant alleles (∼40% of cases) such as BRAF G469A and BRAF G466V. The presence of BRAF V600E in LA has prompted clinical trials testing selective BRAF inhibitors such as vemurafenib in BRAF V600E -mutant patients. Despite promising clinical efficacy, both innate and acquired resistance often result from reactivation of MAPK pathway signaling, thus limiting durable responses to the current BRAF inhibitors. Further, the optimal therapeutic strategy to block non-V600E BRAF-mutant LA remains unclear. Here, we report the efficacy of the Raf proto-oncogene serine/ threonine protein kinase (RAF) inhibitor, PLX8394, that evades MAPK pathway reactivation in BRAF-mutant LA models. We show that PLX8394 treatment is effective in both BRAF V600E and certain non-V600 LA models, in vitro and in vivo. PLX8394 was effective against treatment-naive BRAF-mutant LAs and those with acquired vemurafenib resistance caused by an alternatively spliced, truncated BRAF V600E that promotes vemurafenib-insensitive MAPK pathway signaling. We further show that acquired PLX8394 resistance occurs via EGFR-mediated RAS-mTOR signaling and is prevented by upfront combination therapy with PLX8394 and either an EGFR or mTOR inhibitor. Our study provides a biological rationale and potential polytherapy strategy to aid the deployment of PLX8394 in lung cancer patients.ncogenic mutations in the BRAF serine/threonine protein kinase occur in a wide spectrum of solid tumor malignancies, most notably melanoma, colorectal cancer, and lung adenocarcinoma (1). Mutant BRAF promotes tumor growth by hyperactivating the RAF-MEK-ERK signaling cascade (2-5). BRAF V600E is the most common oncogenic form of BRAF in most tumor types, and selective RAF inhibitors such as vemurafenib and dabrafenib have demonstrated clinical efficacy in melanoma and LA harboring BRAF V600E (6-9). Despite these findings, ∼15% of BRAF mutant cancers do not respond to BRAF inhibitors, and the majority of patients who achieve a response will inevitably acquire resistance to these targeted agents, predominantly through reactivation of MAPK pathway signaling (4, 10-16).The clinical efficacy of RAF inhibitors depends on the degree of suppression of MAPK pathway output (8). Vemurafenib and dabrafenib paradoxically activate the MAPK pathway in cells with oncogenic RAS or increased upstream receptor signaling, thereby enhancing cellular proliferation that can promote cutaneous squamous cell carcinomas and keratoacanthomas that often harbor RAS mutations, and potentially other RAS-driven malignancies (17-25). Combination therapy with a MEK i...

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“…10) Figure 1b shows representative kinase inhibitors having a number of substituents at various positions in the 7-azaindole ring. [11][12][13][14][15][16] Among them, vemurafenib (1), a B-RAF kinase (serinethreonine kinase [STK]) inhibitor, is the first FDA-approved 7-azaindole-based kinase drug for the treatment of melanoma.…”

Section: Introductionmentioning

confidence: 99%

“…1b. Apart from PLX-8394 (6), a second-generation BRAF kinase inhibitor, 16) other compounds have been developed targeting various kinds of kinases including Janus kinase 3 (JAK3; a cytoplasmic tyrosine kinase [TK]), 12) colony stimulating factor 1 receptor (CSF1R; a receptor TK), 13) aurora kinases (STK), 14) and rho-associated, coiled-coil-containing protein kinase 1 (ROCK1; STK). 15) Comprehensive survey of a drug discovery database (substructure-search using Thomson Reuters Integrity SM database 18) as of March 2017) revealed that more than 90 kinds of kinases have been shown sensitive to 7-azaindole-based kinase inhibitors-sufficient to cover the whole human kinome as shown in Fig.…”

Section: Introductionmentioning

confidence: 99%