AZD6244 (Selumetinib)

AZD6244 is a highly potent and selective inhibitor of MEK1/2 with IC50 value of 14.1nM against MEK1 [1].

AZD6244 is a second generation MEK1/2 inhibitor. In the radioactive assay, AZD6244 shows potent inhibition against the purified MEK1without the competition with ATP. Besides, it is a selective inhibitor since it has no obvious inhibition against other tyrosine kinases including MKK6, EGFR, ErbB2 and B-Raf et al. In the cellular assay, AZD6244 inhibits the phosphorylation of ERK1/2 which are the direct substrates of MEK1/2. The IC50 value is 10.3nM. It also inhibits the EGF-induced phosphorylation of ERK1/2 but not ERK5 in A431 cells. Since MEK is important in cell proliferation, the block of MEK1/2 caused by AZD6244 leads to a growth inhibition in the cell lines containing activating B-Raf and Ras mutations with IC50 values ranging from 59 to 473nM. Furthermore, the administration of AZD6244 can significantly inhibit tumor growth both in the HT-29 xenograft model and the BxPC3 pancreatic tumor xenograft model [1].

References:
[1] Yeh TC, Marsh V, Bernat BA, Ballard J, Colwell H, Evans RJ, Parry J, Smith D, Brandhuber BJ, Gross S, Marlow A, Hurley B, Lyssikatos J, Lee PA, Winkler JD, Koch K, Wallace E. Biological characterization of ARRY-142886 (AZD6244), a potent, highly selective mitogen-activated protein kinase kinase 1/2 inhibitor. Clin Cancer Res. 2007 Mar 1;13(5):1576-83.

Autophagy regulates Selumetinib (AZD6244) induced-apoptosis in colorectal cancer cells.[Pubmed:27448918]

Eur J Med Chem. 2016 Oct 21;122:611-618.

OBJECTIVE: As Selumetinib is a MEK1/2 inhibitor that has gained interest as an anti-tumor agent, the present study was designed to investigate autophagy involvement on Selumetinib-induced apoptosis in colorectal cancer (CRC) cells. METHODS: CRC cells death and cycle studies were assessed by AnnexinV-FITC and PI staining, respectively. Autophagy flux was analysed by Western Blot (LC3II and p62 protein levels) and retroviral infection of SW480 cells for siBecn1 RNA interference experiments. Confocal microscopy was used to determine mCherry-EGFP-LC3 distribution. KEY FINDINGS: The Selumetinib effects were concentration-dependent in SW480 cell line. Whereas 1 muM exerted an arrest in the cell cycle (G1 phase), higher concentrations (10 muM) induced cell death, which was accompanied by autophagy blockage in its last stages. Autophagy induction by Rapamycin (RAPA) increased cell survival, whereas pharmacology autophagy inhibition by Bafilomycin A1 (BAF), Chloroquine (CQ) or 3-Methyladenine (3-MA) increased Selumetinib-induced CRC cells death. CONCLUSIONS: Altogether, these results suggest that autophagy plays a fundamental role in CRC cells response to Selumetinib. In addition, the combination of Selumetinib with autophagy inhibitors may be a useful therapeutic strategy to enhance its activity against colorectal tumours.

A phase I trial of the MEK inhibitor selumetinib (AZD6244) in pediatric patients with recurrent or refractory low-grade glioma: a Pediatric Brain Tumor Consortium (PBTC) study.[Pubmed:28339824]

Neuro Oncol. 2017 Aug 1;19(8):1135-1144.

Background: Activation of the mitogen-activated protein kinase pathway is important for growth of pediatric low-grade gliomas (LGGs). The aim of this study was to determine the recommended phase II dose (RP2D) and the dose-limiting toxicities (DLTs) of the MEK inhibitor selumetinib in children with progressive LGG. Methods: Selumetinib was administered orally starting at 33 mg/m2/dose b.i.d., using the modified continual reassessment method. Pharmacokinetic analysis was performed during the first course. BRAF aberrations in tumor tissue were determined by real-time polymerase chain reaction and fluorescence in situ hybridization. Results: Thirty-eight eligible subjects were enrolled. Dose levels 1 and 2 (33 and 43 mg/m2/dose b.i.d.) were excessively toxic. DLTs included grade 3 elevated amylase/lipase (n = 1), headache (n = 1), mucositis (n = 2), and grades 2-3 rash (n = 6). At dose level 0 (25 mg/m2/dose b.i.d, the RP2D), only 3 of 24 subjects experienced DLTs (elevated amylase/lipase, rash, and mucositis). At the R2PD, the median (range) area under the curve (AUC0-infinity) and apparent oral clearance of selumetinib were 3855 ng*h/mL (1780 to 7250 ng x h/mL) and 6.5 L x h-1 x m-2 (3.4 to 14.0 L x h-1 x m-2), respectively. Thirteen of 19 tumors had BRAF abnormalities. Among the 5 (20%) of 25 subjects with sustained partial responses, all at the RP2D, 4 had BRAF aberrations, 1 had insufficient tissue. Subjects received a median of 13 cycles (range: 1-26). Fourteen (37%) completed all protocol treatment (26 cycles [n = 13], 13 cycles [n = 1]) with at least stable disease; 2-year progression-free survival at the RP2D was 69 +/- SE 9.8%. Conclusion: Selumetinib has promising antitumor activity in children with LGG. Rash and mucositis were the most common DLTs.

A phase Ib study of selumetinib (AZD6244, ARRY-142886) in combination with sorafenib in advanced hepatocellular carcinoma (HCC).[Pubmed:27681866]

Ann Oncol. 2016 Dec;27(12):2210-2215.

BACKGROUND: Treatment with sorafenib, although associated with inhibition of tumour growth and angiogenesis in in vivo studies, leads to up-regulation of pERK. The addition of MEK inhibition could potentially abrogate this effect and potentiate anti-tumour activity. This phase I study investigated the maximum tolerated dose (MTD), safety, tolerability, pharmacokinetics (PK) and biomarker correlates of selumetinib combined with sorafenib in patients with advanced hepatocellular carcinoma (HCC). METHODS: Patients with Child-Pugh (CP) score /=6 months in seven patients. The median overall survival was 14.4 months. Selumetinib exposures in combination with sorafenib were comparable to other monotherapy studies. A reduction in permeability-surface area product noted in DCE-MRI with treatment correlated with worse survival outcomes. CONCLUSION: The MTD of selumetinib was 75 mg daily when combined with sorafenib 400 mg twice a day in CP

Selumetinib (AZD6244) is selective, non-ATP-competitive oral MEK1/2 inhibitor, with an IC50 of 14 nM for MEK1. Selumetinib (AZD6244) inhibits ERK1/2 phosphorylation.

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