LY3009120

LY3009120 is a pan-RAF and RAF dimer inhibitor. It inhibits BRAF WT, CRAF, WT, BRAFV600E, and BRAFV600E+G468A with the IC50 values of 9.1, 15, 5.8, and 17 nM, respectively. [1]

RAF is family of serine/threonine-protein kinase mediates Ras GTPases and the MAPK/ERK cascade. It involves in proliferation, differentiation, apoptosis, survival and oncogenic transformation. [1]

In NRAS mutant SK-Mel2 cells or KRAS mutant HCT116 cells, LY3009120 inhibits the kinase activity of CRAF in a dose-dependent manner and induces BRAF/CRAF heterodimerization. It also blocks Phospho-MEK and -ERK and induces minimal paradoxical activation in RAS mutant Cells. Moreover, treatment of BRAF V600E A375 melanoma cells by LY3009120 for 24 hr predominantly induces a G0/G1 arrest with more than 95% cells in G0/G1 phase. [1]

In nude rats bearing A375 xenograft tumors, oral LY3001920 treatment exerts a dose-dependent inhibition of phospho-MEK and –ERK. 15 or 30 mg/kg LY3009120 shows near complete tumor regression in nude rats bearing PDX tumors. [1]

Reference:
1.  Peng SB, Henry JR, Kaufman MD et al. Inhibition of RAF Isoforms and Active Dimers by LY3009120 Leads to Anti-tumor Activities in RAS or BRAF Mutant Cancers. Cancer Cell. 2015 Sep 14;28(3):384-98.

LY3009120, a panRAF inhibitor, has significant anti-tumor activity in BRAF and KRAS mutant preclinical models of colorectal cancer.[Pubmed:27999210]

Oncotarget. 2017 Feb 7;8(6):9251-9266.

Activating mutations in the KRAS and BRAF genes, leading to hyperactivation of the RAS/RAF/MAPK oncogenic signaling cascade, are common in patients with colorectal cancer (CRC). While selective BRAF inhibitors are efficacious in BRAFmut melanoma, they have limited efficacy in BRAFmut CRC patients. In a RASmut background, selective BRAF inhibitors are contraindicated due to paradoxical activation of the MAPK pathway through potentiation of CRAF kinase activity. A way to overcome such paradoxical activation is through concurrent inhibition of the kinase activity of both RAF isoforms. Here, we further examined the effects of LY3009120, a panRAF and RAF dimer inhibitor, in human models of CRC with various mutational backgrounds. We demonstrate that LY3009120 induced anti-proliferative effects in BRAFmut and KRASmut CRC cell lines through G1-cell cycle arrest. The anti-proliferative effects of LY3009120 in KRASmut CRC cell lines phenocopied molecular inhibition of RAF isoforms by simultaneous siRNA-mediated knockdown of ARAF, BRAF and CRAF. Additionally, LY3009120 displayed significant activity in in vivo BRAFmut and KRASmut CRC xenograft models. Examination of potential resistance to LY3009120 demonstrated RAF-independent ERK and AKT activation in the KRASmut CRC cell line HCT 116. These findings describe the preclinical activity of a panRAF inhibitor in a BRAFmut and KRASmut CRC setting.

Oncogenic BRAF Deletions That Function as Homodimers and Are Sensitive to Inhibition by RAF Dimer Inhibitor LY3009120.[Pubmed:26732095]

Cancer Discov. 2016 Mar;6(3):300-15.

UNLABELLED: We have identified previously undiscovered BRAF in-frame deletions near the alphaC-helix region of the kinase domain in pancreatic, lung, ovarian, and thyroid cancers. These deletions are mutually exclusive with KRAS mutations and occur in 4.21% of KRAS wild-type pancreatic cancer. siRNA knockdown in cells harboring BRAF deletions showed that the MAPK activity and cell growth are BRAF dependent. Structurally, the BRAF deletions are predicted to shorten the beta3/alphaC-helix loop and hinder its flexibility by locking the helix in the active alphaC-helix-in conformation that favors dimer formation. Expression of L485-P490-deleted BRAF is able to transform NIH/3T3 cells in a BRAF dimer-dependent manner. BRAF homodimer is confirmed to be the dominant RAF dimer by proximity ligation assays in BRAF deletion cells, which are resistant to the BRAF inhibitor vemurafenib and sensitive to LY3009120, a RAF dimer inhibitor. In tumor models with BRAF deletions, LY3009120 has shown tumor growth regression, whereas vemurafenib is inactive. SIGNIFICANCE: This study discovered oncogenic BRAF deletions with a distinct activation mechanism dependent on the BRAF dimer formation in tumor cells. LY3009120 is active against these cells and represents a potential treatment option for patients with cancer with these BRAF deletions, or other atypical BRAF mutations where BRAF functions as a dimer.

Discovery of 1-(3,3-dimethylbutyl)-3-(2-fluoro-4-methyl-5-(7-methyl-2-(methylamino)pyrido[2,3- d]pyrimidin-6-yl)phenyl)urea (LY3009120) as a pan-RAF inhibitor with minimal paradoxical activation and activity against BRAF or RAS mutant tumor cells.[Pubmed:25965804]

J Med Chem. 2015 May 28;58(10):4165-79.

The RAS-RAF-MEK-MAPK cascade is an essential signaling pathway, with activation typically mediated through cell surface receptors. The kinase inhibitors vemurafenib and dabrafenib, which target oncogenic BRAF V600E, have shown significant clinical efficacy in melanoma patients harboring this mutation. Because of paradoxical pathway activation, both agents were demonstrated to promote growth and metastasis of tumor cells with RAS mutations in preclinical models and are contraindicated for treatment of cancer patients with BRAF WT background, including patients with KRAS or NRAS mutations. In order to eliminate the issues associated with paradoxical MAPK pathway activation and to provide therapeutic benefit to patients with RAS mutant cancers, we sought to identify a compound not only active against BRAF V600E but also wild type BRAF and CRAF. On the basis of its superior in vitro and in vivo profile, compound 13 was selected for further development and is currently being evaluated in phase I clinical studies.

Inhibition of RAF Isoforms and Active Dimers by LY3009120 Leads to Anti-tumor Activities in RAS or BRAF Mutant Cancers.[Pubmed:26343583]

Cancer Cell. 2015 Sep 14;28(3):384-98.

LY3009120 is a pan-RAF and RAF dimer inhibitor that inhibits all RAF isoforms and occupies both protomers in RAF dimers. Biochemical and cellular analyses revealed that LY3009120 inhibits ARAF, BRAF, and CRAF isoforms with similar affinity, while vemurafenib or dabrafenib have little or modest CRAF activity compared to their BRAF activities. LY3009120 induces BRAF-CRAF dimerization but inhibits the phosphorylation of downstream MEK and ERK, suggesting that it effectively inhibits the kinase activity of BRAF-CRAF heterodimers. Further analyses demonstrated that LY3009120 also inhibits various forms of RAF dimers including BRAF or CRAF homodimers. Due to these unique properties, LY3009120 demonstrates minimal paradoxical activation, inhibits MEK1/2 phosphorylation, and exhibits anti-tumor activities across multiple models carrying KRAS, NRAS, or BRAF mutation.