MPC-6827 (Azixa) is a small-molecule microtubule-destabilizing agent that binds to the same (or nearby) sites on β-tubulin as colchicine.[1]
Tubulin is a heterodimer consisting of an αand βmonomer, it can be covalently labeled with [3H] colchicine by near UV irradiation. Most of the label appears in β tubulin. Colchicine binds to tubulin with a stoichiometry of one and inhibits microtubule assembly substoichiometrically. Colchicine binding to tubulin exhibits pseudoirreversible kinetics; it displays a fast step followed by a slow step involving conformational changes of both ligand and tubulin. The tubulin, in turn, promotes fluorescence characteristic of the tropolone moiety of colchicine. [2]
MPC-6827 is a small-molecule microtubule-destabilizing agent that causes mitotic arrest and cell death. MPC-6827 interfere with microtubule dynamics, leading to arrest of dividing cells in the G2-M phase of the cell cycle, which eventually results in apoptotic cell death.[1]
In vivo, MPC-6827 significantly inhibits the growth of various subcutaneously implanted tumor lines. MPC-6827 has also been shown to be a vascular-disrupting agent (VDA) in a human ovarian carcinoma xenograft model. It also has shown synergism with carboplatin in a mouse xenograft model. Furthermore, MPC-6827 has been shown to inhibit the growth of human glioblastoma tumor cell line (D-54) implanted intracranially in athymic nude mice. [1]
References:
[1] Tsimberidou AM1, Akerley W, Schabel MC, etal. , Phase I clinical trial of MPC-6827 (Azixa), a microtubule destabilizing agent, in patients with advanced cancer. Mol Cancer Ther. 2010 Dec;9(12):3410-9.
[2] Uppuluri S, Knipling L, Sackett DL, Wolff J. Localization of the colchicine-binding site of tubulin. Proc Natl Acad Sci U S A. 1993 Dec 15;90(24):11598-602.