MEK162 (ARRY-162, ARRY-438162)

Cell Assay [2]
MCF7 cells infected as indicated are seeded in 12-well plates (2×104). After 24 hours, cells are treated with BEZ235 (100 or 200 nM), BKM120 (0.75 or 1 μM), GDC-0941 (1 μM), or MK2206 (2 μM) alone or in combination with MEK162 (1 μM), BI-D1870 (10 μM), or AZD6244 (1 μM), as indicated in text. Cell numbers are quantified by fixing cells with 4% glutaraldehyde or methanol, washing the cells twice in H2O, and staining the cells with 0.1% crystal violet. The dye is subsequently extracted with 10% acetic acid, and its absorbance is determined (570 nm). Growth curves are performed in triplicate. Viability assays with CellTiter-Glo are performed by plating 2,000 cells in 96-well plates, adding the drug at 24 hours, and assaying 4 to 5 days after drug addition. Cell-cycle and hypodiploid apoptotic cells are quantified by flow cytometry. Briefly, cells are washed with PBS, fixed in cold 70% ethanol, and then stained with propidium iodide while being treated with RNase. Quantitative analysis of sub-G1 cells is carried out in a FACScalibur cytometer using Cell Quest software[2].

Animal Administration [1][2]
Mice[2] Six-week-old female athymic nude Foxn1nu mice are purchased from Harlan Laboratories. Mice are housed in air-filtered laminar flow cabinets with a 12-hour light/12-hour dark cycle and given food and water ad libitum. Mice are handled with aseptic procedures and allowed to acclimatize to local conditions for 1 week before the experimental manipulations. A 17β-estradiol pellet is implanted subcutaneously into each mouse 1 day before cell injection. 107 MCF-GFP or MCF7-RSK4 cells are resuspended in PBS/Matrigel (1:1) and injected subcutaneously into the right flank of each mouse in 200 μL of final volume. Treatments began when tumors reached an average size of 250 mm3 and are thus considered as established growing xenografts. Mice are treated once daily with placebo, BEZ235, BKM120, MK-2206, or MEK162 by oral gavage. BEZ235 (25-30 mg/kg, 6IW [6 days on 1 day off]) and BKM120 (30 mg/kg, 6IW) are dissolved in 10% NMP-90% PEG, freshly formulated, and administrated within 30 minutes. MK-2206 (100 mg/kg, 3IW) is formulated in 30% Captisol and MEK162 (6 mg/kg, BID) in 0.5% Tween-80, 1% carboxymethyl cellulose. For tumor growth studies, mice are treated for 7-24 days, depending on the xenograft model and treatment regime. Tumor xenografts are measured with calipers 3 times a week, and tumor volume is determined using the following formula: (length×width2)×(π/6). At the end of the experiment, the animals are anesthetized with 1.5% isofluorane-air mixture and killed by cervical dislocation. Tumors are removed 2 hours following the last administration. Rats[1] Rat collagen-induced arthritis (CIA) and rat adjuvant-induced arthritis (AIA) models are used to determine efficacy in the subacute inflammation setting. In the CIA studies, rats with established disease, induced by injections of Type II collagen, are treated with 0.3, 1 or 3 mg/kg ARRY-438162 (PO, BID) with or without 30 mg/kg ibuprofen (PO, QD) for six days. Body weight and ankle diameter are used to monitor disease progression on days 0-7. The AIA model is induced by an injection of a lipoidal amine in FCA on day 0. The AIA rats are treated with 1, 3 or 10 mg/kg ARRY-438162 (PO, QD) beginning on day 8 and continuing for 6 days, with or without the addition of 0.05 mg/kg methotrexate (PO, QD) which is dosed days 0-13. Disease progression is monitored on days 7-14 measuring both paw diameter and body weight.

References:
[1]. J Pheneger, et al. 2006, ACR Annual Scientific Meeting. Abst 794. [2]. Serra V, et al. RSK3/4 mediate resistance to PI3K pathway inhibitors in breast cancer. J Clin Invest, 2013, 123(6), 2551-2563. [3]. Kiessling MK, et al. Mutant HRAS as novel target for MEK and mTOR inhibitors. Oncotarget. 2015 Dec 8;6(39):42183-96. [4]. Cheng H, et al. PIK3CA(H1047R)- and Her2-initiated mammary tumors escape PI3K dependency by compensatory activation of MEK-ERK signaling. Oncogene. 2016 Jun 9;35(23):2961-70. [5]. Seip K, et al. Fibroblast-induced switching to the mesenchymal-like phenotype and PI3K/mTOR signaling protects melanoma cells from BRAF inhibitors. Oncotarget. 2016 Apr 12;7(15):19997-20015.