Cobimetinib (Synonyms: GDC-0973, RG-7420, XL518)

Cobimetinib is a selective inhibitor of mitogen-activated protein kinase kinase (MEK) with IC50 value of 0.9 nM [1].
MEK is a kinase enzyme which selectively phosphorylates Ser/Thr and Tyr residues and involved in the mitogen-activated protein kinase (MAPK) signaling pathways that play an important role in regulation of cell proliferation, survival, differentiation, motility and angiogenesis [2].
In a KRAS G13D and B-RAF G464V mutant MDA-MB-231T breast adenocarcinoma cells, Cobimetinib inhibited MEK with IC50 value of 0.2 nM [1]. In pharmacokinetic-pharmacodynamic (PK-PD) model, Cobimetinib showed a sustained tumor pharmacodynamic response due to longer residence in tumor than in plasma [3].
In WM-266-4 xenograft mice, Cobimetinib decreased %pERK in tumor with IC50 values of 0.78 (WM-266-4) and 0.52 mM. Also, Cobimetinib (3.89 mM) increased IC50 value in WM-266-4 mice. In A375 xenograft mice, Cobimetinib (0.3-30 mg/kg) showed antitumor efficacy in a dose-dependent way. Cobimetinib is currently in phase I clinical trials as a potential antitumor agent [3].
References:
[1]. Rice KD, Aay N, Anand NK, et al. Novel Carboxamide-Based Allosteric MEK Inhibitors: Discovery and Optimization Efforts toward XL518 (GDC-0973). ACS Med Chem Lett, 2012, 3(5): 416-421.
[2]. Akinleye A, Furqan M, Mukhi N, et al. MEK and the inhibitors: from bench to bedside. J Hematol Oncol, 2013, 6: 27.
[3]. Wong H, Vernillet L, Peterson A, et al. Bridging the gap between preclinical and clinical studies using pharmacokinetic-pharmacodynamic modeling: an analysis of GDC-0973, a MEK inhibitor. Clin Cancer Res, 2012, 18(11): 3090-3099.