Antitumor Properties of RAF709, a Highly Selective and Potent Inhibitor of RAF Kinase Dimers, in Tumors Driven by Mutant RAS or BRAF

Shao, Wenlin; Mishina, Yuji; Feng, Yun; Caponigro, Giordano; Cooke, Vesselina G.; Rivera, Stacy; Wang, Yingyun; Shen, Fang; Korn, Joshua M.; Griner, Lesley A. Mathews; Nishiguchi, Gisele; Rico, Alice; Tellew, John; Haling, Jacob R.; Aversa, Robert J.; Polyakov, Valery; Zang, Richard; Hekmat-Nejad, Mohammad; Amiri, Payman; Singh, Mallika; Keen, Nicholas; Dillon, Michael P.; Lees, Emma; Ramurthy, Savithri; Sellers, William R.; Stuart, Darrin D.

doi:10.1158/0008-5472.can-17-2033

Cited by 30 publications

(24 citation statements)

References 38 publications

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“…Additionally, the D154Q substitution did not affect PI3K activity for either mutant, suggesting that RAS multimerization plays a role in MAPK, but not PI3K signaling. This property raised the hypothesis that KRAS Q61H would show enhanced sensitivity to the RAF inhibitor RAF709, which was confirmed in our model systems (44). However, whether this finding is generalizable to human lung cancers, which are notoriously heterogeneous, will require additional study.…”

Section: Discussionsupporting

confidence: 73%

“…The observations that KRAS Q61H preferentially signals through MAPK and depends on RAF multimerization raises the possibility that KRAS Q61H -bearing cells will be sensitive to inhibitors of these mechanisms. In particular we anticipated that RAF inhibitors that function in the context of the RAF dimer, such as RAF709 (44), would show increased activity in KRAS Q61H . We exposed isogenic RASdependent MEF cells (12) to MEK inhibitors selumetinib and trametinib and RAF709.…”

Section: Kras Q61h Is a Marker Of Sensitivity To Mek Inhibitors And Amentioning

confidence: 99%

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KRASQ61H Preferentially Signals through MAPK in a RAF Dimer-Dependent Manner in Non–Small Cell Lung Cancer

et al. 2020

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Assembly of RAS molecules into complexes at the cell membrane is critical for RAS signaling. We previously showed that oncogenic KRAS codon 61 mutations increase its affinity for RAF, raising the possibility that KRAS Q61H , the most common KRAS mutation at codon 61, upregulates RAS signaling through mechanisms at the level of RAS assemblies. We show here that KRAS Q61H exhibits preferential binding to RAF relative to PI3K in cells, leading to enhanced MAPK signaling in in vitro models and human NSCLC tumors. X-ray crystallography of KRAS Q61H :GTP revealed that a hyperdynamic switch 2 allows for a more stable interaction with switch 1, suggesting that enhanced RAF activity arises from a combination of absent intrinsic GTP hydrolysis activity and increased affinity for RAF. Disruption of KRAS Q61H assemblies by the RAS oligomerdisrupting D154Q mutation impaired RAF dimerization and altered MAPK signaling but had little effect on PI3K signaling. However, KRAS Q61H oligomers but not KRAS G12D oligomers were disrupted by RAF mutations that disrupt RAF-RAF interactions. KRAS Q61H cells show enhanced sensitivity to RAF and MEK inhibitors individually, whereas combined treatment elicited synergistic growth inhibition. Furthermore, KRAS Q61H tumors in mice exhibited high vulnerability to MEK inhibitor, consistent with cooperativity between KRAS Q61H and RAF oligomerization and dependence on MAPK signaling. These findings support the notion that KRAS Q61H and functionally similar mutations may serve as predictive biomarkers for targeted therapies against the MAPK pathway. Significance: These findings show that oncogenic KRAS Q61H forms a cooperative RAS-RAF ternary complex, which renders RAS-driven tumors vulnerable to MEKi and RAFi, thus establishing a framework for evaluating RAS biomarker-driven targeted therapies. Recently, we reported a RAS mutation, D154Q, which neutralizes the suppressive effects of KRAS WT in the context of oncogenic KRAS. This mutation was designed on the basis of a RAS-RAS interaction that occurs via an a4-a5 interface seen in some RAS crystal structures (12). Recent NMR studies of RAS molecules bound to nanodisks also

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Section: Discussionsupporting

confidence: 73%

Section: Kras Q61h Is a Marker Of Sensitivity To Mek Inhibitors And Amentioning

confidence: 99%

KRASQ61H Preferentially Signals through MAPK in a RAF Dimer-Dependent Manner in Non–Small Cell Lung Cancer

et al. 2020

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“…Our finding suggests that cotargeting BRAF, CRAF, RAC1, and ATG7 could show efficacy in KRAS mutant cells while reducing general toxicity in normal cells. Although we do not currently have paralog-specific inhibitors against BRAF and CRAF, we attempted to support the translational potential of our findings by combining RAC1 and ATG7 siRNAs with two selective inhibitors of the MAPK pathway: the US Food and Drug Administration (FDA)-approved MEK inhibitor trametinib and a recently disclosed RAF inhibitor, RAF709, that has little paradoxical effect in RAS mutant cells (46,47). Depleting ATG7 and/or RAC1 sensitized the KRAS mutant cell lines HCT116 and MIA PaCa-2 to both RAF709 and trametinib, with a decrease in IC 50 values between threefold and sevenfold ( Fig.…”

Section: Cotargeting Raf and Autophagy Enhances Cell Cycle Arrest Andmentioning

confidence: 99%

MAP kinase and autophagy pathways cooperate to maintain RAS mutant cancer cell survival

Lee

Yuan

et al. 2019

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

100

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Oncogenic mutations in the small GTPase KRAS are frequently found in human cancers, and, currently, there are no effective targeted therapies for these tumors. Using a combinatorial siRNA approach, we analyzed a panel ofKRASmutant colorectal and pancreatic cancer cell lines for their dependency on 28 gene nodes that represent canonical RAS effector pathways and selected stress response pathways. We found that RAF node knockdown best differentiatedKRASmutant andKRASWT cancer cells, suggesting RAF kinases are key oncoeffectors forKRASaddiction. By analyzing all 376 pairwise combination of these gene nodes, we found that cotargeting the RAF, RAC, and autophagy pathways can improve the capture ofKRASdependency better than targeting RAF alone. In particular, codepletion of the oncoeffector kinases BRAF and CRAF, together with the autophagy E1 ligase ATG7, gives the best therapeutic window betweenKRASmutant cells and normal, untransformed cells. Distinct patterns of RAS effector dependency were observed acrossKRASmutant cell lines, indicative of heterogeneous utilization of effector and stress response pathways in supporting KRAS addiction. Our findings revealed previously unappreciated complexity in the signaling network downstream of theKRASoncogene and suggest rational target combinations for more effective therapeutic intervention.

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“…In such a scenario, prevention of pathway reactivation would maintain pathway suppression thereby improving antitumor efficacy. Strategies to block pathway reactivation have focused on cotargeting other MAPK pathway components such as RAF and ERK (10,11), as cotargeting upstream RTKs was generally considered likely to be ineffective based on the dogma that mutant KRAS is constitutively active and does not require further upstream signaling input (12,13). However, this dogma was challenged by the recent development of KRAS G12C -specific inhibitors (G12Ci) that bind and stabilize KRAS G12C in its guanosine diphosphate (GDP)-bound inactive conformation (14)(15)(16).…”

Section: Introductionmentioning

confidence: 99%

SHP2 Inhibition Overcomes RTK-Mediated Pathway Reactivation in KRAS-Mutant Tumors Treated with MEK Inhibitors

Lu¹,

Liu²,

Velazquez³

et al. 2019

Molecular Cancer Therapeutics

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FGFR1 was recently shown to be activated as part of a compensatory response to prolonged treatment with the MEK inhibitor trametinib in several KRAS-mutant lung and pancreatic cancer cell lines. We hypothesize that other receptor tyrosine kinases (RTK) are also feedback-activated in this context. Herein, we profile a large panel of KRAS-mutant cancer cell lines for the contribution of RTKs to the feedback activation of phospho-MEK following MEK inhibition, using an SHP2 inhibitor (SHP099) that blocks RAS activation mediated by multiple RTKs. We find that RTK-driven feedback activation widely exists in KRAS-mutant cancer cells, to a less extent in those harboring the G13D variant, and involves several RTKs, including EGFR, FGFR, and MET. We further demonstrate that this pathway feedback activation is mediated through mutant KRAS, at least for the G12C, G12D, and G12V variants, and wild-type KRAS can also contribute significantly to the feedback activation. Finally, SHP099 and MEK inhibitors exhibit combination benefits inhibiting KRAS-mutant cancer cell proliferation in vitro and in vivo. These findings provide a rationale for exploration of combining SHP2 and MAPK pathway inhibitors for treating KRAS-mutant cancers in the clinic.

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Antitumor Properties of RAF709, a Highly Selective and Potent Inhibitor of RAF Kinase Dimers, in Tumors Driven by Mutant RAS or BRAF

Cited by 30 publications

References 38 publications

KRASQ61H Preferentially Signals through MAPK in a RAF Dimer-Dependent Manner in Non–Small Cell Lung Cancer

KRASQ61H Preferentially Signals through MAPK in a RAF Dimer-Dependent Manner in Non–Small Cell Lung Cancer

MAP kinase and autophagy pathways cooperate to maintain RAS mutant cancer cell survival

SHP2 Inhibition Overcomes RTK-Mediated Pathway Reactivation in KRAS-Mutant Tumors Treated with MEK Inhibitors

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