GDC-0879

IC50: 0.13 nM against purified B-Raf V600E enzyme; a cellular pERK IC50 of 63 nM in the MALME-3M cell line

GDC-0879 is synthsized as a potent and selective B-Raf inhibitor. The Raf/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase signaling pathway is reported to be involved in cellular responses, which is relevant to tumorigenesis.

In vitro: GDC-0879 is a B-Raf inhibitor against various in vitro and cell-based assays, such as A375 melanoma and Colo205 colorectal carcinoma cell lines, both of which are V600E B-Raf mutant. When screened against a panel of 140 kinases at its efficaciou dose, GDC-0879 showed expected activity only against C-Raf [1].

In vivo: In mice treated by GDC-0879, both cell line-and patient-derived BRAFV600E tumors exhibited stronger and more sustained pharmacodynamic inhibition (>90% for 8 hours) and improved survival compared with mutant KRAS-expressing tumors. Moreover, it was found that the responsiveness of BRAFV600E melanoma cells to GDC-0879 could be dramatically altered by pharmacologic and genetic modulation of phosphatidylinositol 3-kinase pathway activity [2].

Clinical trial: GDC-0879 is still in the preclinical development stage, and no clinical data are available currently.

References:
[1] Wong H, Belvin M, Herter S, Hoeflich KP, Murray LJ, Wong L, Choo EF.  Pharmacodynamics of 2-[4-[(1E)-1-(hydroxyimino)-2,3-dihydro-1H-inden-5-yl]-3-(pyridine-4-yl)-1H-pyrazol-1-yl]ethan-1-ol (GDC-0879), a potent and selective B-Raf kinase inhibitor: understanding relationships between systemic concentrations, phosphorylated mitogen-activated protein kinase kinase 1 inhibition, and efficacy. J Pharmacol Exp Ther. 2009 Apr;329(1):360-7.
[2] Hoeflich KP, Herter S, Tien J, Wong L, Berry L, Chan J, O'Brien C, Modrusan Z, Seshagiri S, Lackner M, Stern H, Choo E, Murray L, Friedman LS, Belvin M.  Antitumor efficacy of the novel RAF inhibitor GDC-0879 is predicted by BRAFV600E mutational status and sustained extracellular signal-regulated kinase/mitogen-activated protein kinase pathway suppression. Cancer Res. 2009 Apr 1;69(7):3042-51.

Validation and application of a liquid chromatography-tandem mass spectrometric method for the determination of GDC-0879 and its metabolite in dog plasma using solid phase extraction.[Pubmed:22717139]

J Pharm Biomed Anal. 2012 Nov;70:354-61.

A liquid-chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the determination of GDC-0879 and its ketone metabolite (M1) in dog plasma to support preclinical toxicokinetic evaluation. The method consisted of solid phase extraction for sample preparation and LC-MS/MS analysis in positive ion mode using electrospray ionization for analysis. D(4)-GDC-0879 and (13)C(2)-D(2)-M1 were used as internal standards. A quadratic regression (weighted 1/concentration(2)) was used to fit calibration curves over the concentration range of 1-1000 ng/ml for both GDC-0879 and M1. The accuracy (%bias) at the lower limit of quantitation (LLOQ) was 12.0% and 2.0% for GDC-0879 and M1, respectively. The precision (%CV) for samples at the LLOQ was 11.3% and 2.6% for GDC-0879 and M1, respectively. For quality control samples at 3.00, 400 and 800 ng/ml, the between run %CV was GDC-0879 and GDC-0879 and from -0.8 to 2.7% for M1. GDC-0879 and M1 were stable in dog plasma for at least 44 days at -70 degrees C.

Pharmacodynamics of 2-[4-[(1E)-1-(hydroxyimino)-2,3-dihydro-1H-inden-5-yl]-3-(pyridine-4-yl)-1H-pyraz ol-1-yl]ethan-1-ol (GDC-0879), a potent and selective B-Raf kinase inhibitor: understanding relationships between systemic concentrations, phosphorylated mitogen-activated protein kinase kinase 1 inhibition, and efficacy.[Pubmed:19147858]

J Pharmacol Exp Ther. 2009 Apr;329(1):360-7.

The Raf/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase signaling pathway is involved in cellular responses relevant to tumorigenesis, including cell proliferation, invasion, survival, and angiogenesis. 2-[4-[(1E)-1-(Hydroxyimino)-2,3-dihydro-1H-inden-5-yl]-3-(pyridine-4-yl)-1H-pyraz ol-1-yl]ethan-1-ol (GDC-0879) is a novel, potent, and selective B-Raf inhibitor. The objective of this study was to characterize the relationship between GDC-0879 plasma concentrations and tumor growth inhibition in A375 melanoma and Colo205 colon cancer xenografts and to understand the pharmacodynamic (PD) marker response requirements [phosphorylated (p)MEK1 inhibition] associated with tumor growth inhibition in A375 xenografts. Estimates of GDC-0879 plasma concentrations required for tumor stasis obtained from fitting tumor data to indirect response models were comparable, at 4.48 and 3.27 microM for A375 and Colo205 xenografts, respectively. This was consistent with comparable in vitro potency of GDC-0879 in both cell lines. The relationship between GDC-0879 plasma concentrations and pMEK1 inhibition in the tumor was characterized in A375 xenografts after oral doses of 35, 50, and 100 mg/kg. Fitting pMEK1 inhibition to an indirect response model provided an IC(50) estimate of 3.06 microM. pMEK1 inhibition was further linked to A375 tumor volume data from nine different GDC-0879 dosing regimens using an integrated pharmacokinetic-PD model. A simulated PD marker response curve plot of K (rate constant describing tumor growth inhibition) versus pMEK1 inhibition generated using pharmacodynamic parameters estimated from this model, showed a steep pMEK1 inhibition-response curve consistent with an estimated Hill coefficient of approximately equal 8. A threshold of >40% pMEK1 inhibition is required for tumor growth inhibition, and a minimum of approximately 60% pMEK1 inhibition is required for stasis in A375 xenografts treated with GDC-0879.

Disposition of GDC-0879, a B-RAF kinase inhibitor in preclinical species.[Pubmed:19552528]

Xenobiotica. 2009 Sep;39(9):700-9.

1. The pharmacokinetics and disposition of GDC-0879, a small molecule B-RAF kinase inhibitor, was characterized in mouse, rat, dog, and monkey. 2. In mouse and monkey, clearance (CL) of GDC-0879 was moderate (18.7-24.3 and 14.5 +/- 2.1 ml min(-1) kg(-1), respectively), low in dog (5.84 +/- 1.06 ml min(-1) kg(-1)) and high in rat (86.9 +/- 14.2 ml min(-1) kg(-1)). The volume of distribution across species ranged from 0.49 to 1.9 l kg(-1). Mean terminal half-life values ranged from 0.28 h in rats to 2.97 h in dogs. Absolute oral bioavailability ranged from 18% in dog to 65% in mouse. 3. Plasma protein binding of GDC-0879 in mouse, rat, dog, monkey, and humans ranged from 68.8% to 81.9%. 4. In dog, the major ketone metabolite (G-030748) of GDC-0879 appeared to be formation rate-limited. 5. Based on assessment in dogs, the absorption of GDC-0879 appeared to be sensitive to changes in gut pH, food and salt form (solubililty), with approximately three- to four-fold change in areas under the curve (AUCs) observed.

Antitumor efficacy of the novel RAF inhibitor GDC-0879 is predicted by BRAFV600E mutational status and sustained extracellular signal-regulated kinase/mitogen-activated protein kinase pathway suppression.[Pubmed:19276360]

Cancer Res. 2009 Apr 1;69(7):3042-51.

Oncogenic activation of the BRAF serine/threonine kinase has been associated with initiation and maintenance of melanoma tumors. As such, development of pharmacologic agents to target RAF proteins or their effector kinases is an area of intense investigation. Here we report the biological properties of GDC-0879, a highly selective, potent, and orally bioavailable RAF small-molecule inhibitor. We used extracellular signal-regulated kinase (ERK)-1/2 and mitogen-activated protein kinase/ERK kinase (MEK)-1/2 phosphorylation as biomarkers to explore the relationship between tumor outcome and pharmacodynamic inhibition of the RAF-MEK-ERK pathway. In GDC-0879-treated mice, both cell line- and patient-derived BRAF(V600E) tumors exhibited stronger and more sustained pharmacodynamic inhibition (>90% for 8 hours) and improved survival compared with mutant KRAS-expressing tumors. Despite the involvement of activated RAF signaling in RAS-induced tumorigenesis, decreased time to progression was observed for some KRAS-mutant tumors following GDC-0879 administration. Moreover, striking differences were noted for RAF and MEK inhibition across a panel of 130 tumor cell lines. Whereas GDC-0879-mediated efficacy was associated strictly with BRAF(V600E) status, MEK inhibition also attenuated proliferation and tumor growth of cell lines expressing wild-type BRAF (81% KRAS mutant, 38% KRAS wild type). The responsiveness of BRAF(V600E) melanoma cells to GDC-0879 could be dramatically altered by pharmacologic and genetic modulation of phosphatidylinositol 3-kinase pathway activity. These data suggest that GDC-0879-induced signaling changes are dependent on the point of oncogenic activation within the RAS network. Taken together, these studies increase our understanding of the molecular determinants for antitumor efficacy resulting from RAF pathway inhibition and have implications for therapeutic intervention in the clinic.

RAF inhibitors prime wild-type RAF to activate the MAPK pathway and enhance growth.[Pubmed:20130576]

Nature. 2010 Mar 18;464(7287):431-5.

Activating mutations in KRAS and BRAF are found in more than 30% of all human tumours and 40% of melanoma, respectively, thus targeting this pathway could have broad therapeutic effects. Small molecule ATP-competitive RAF kinase inhibitors have potent antitumour effects on mutant BRAF(V600E) tumours but, in contrast to mitogen-activated protein kinase kinase (MEK) inhibitors, are not potent against RAS mutant tumour models, despite RAF functioning as a key effector downstream of RAS and upstream of MEK. Here we show that ATP-competitive RAF inhibitors have two opposing mechanisms of action depending on the cellular context. In BRAF(V600E) tumours, RAF inhibitors effectively block the mitogen-activated protein kinase (MAPK) signalling pathway and decrease tumour growth. Notably, in KRAS mutant and RAS/RAF wild-type tumours, RAF inhibitors activate the RAF-MEK-ERK pathway in a RAS-dependent manner, thus enhancing tumour growth in some xenograft models. Inhibitor binding activates wild-type RAF isoforms by inducing dimerization, membrane localization and interaction with RAS-GTP. These events occur independently of kinase inhibition and are, instead, linked to direct conformational effects of inhibitors on the RAF kinase domain. On the basis of these findings, we demonstrate that ATP-competitive kinase inhibitors can have opposing functions as inhibitors or activators of signalling pathways, depending on the cellular context. Furthermore, this work provides new insights into the therapeutic use of ATP-competitive RAF inhibitors.