Fosbretabulin disodium

개요Combretastatin A4 phosphate disodium salt, also known as fosbretabulin disodium or CA4P, is a microtubule destabilizing drug, a water-soluble prodrug of combretasain a4(ca4) and a tumor vascular-targeting agent.microtubule is the cylindrical and filamentous structure that required for cell shape, migration, cilia and flagella mobility etc. tubulin is the major component of microtubulesin proliferative endothelial cells, ca4p (dose less than 1/10 of the max. tolerated dose) leaded to tumor vascular shutdown, and short drug exposure of ca4p caused significant long-term anti-proliferative and cytotoxic effects. [1] in ca40 treated endothelia cell, myosin light chain was phosphorylated and lead to actinomyosin contractility, assembly of actin stress fibers and focal adhesions formation. [2] in huvec cells, ca4p blocked growth factor–induced endothelial cell proliferation and migration and impaired capillary tube formation. [3]in c57bl/6 mice, ca4p treatment in combination with mab against ve-cardherin facilitated b16 melanoma tumor necrosis and inhibited tumor neoangionesis. [3] in human breast cancer models in vivo, 6 hours after ca4p administration showed a 93% decreased functional vascular volume and lasted over the next 12 hours. [1]

Combretastatin A-4 phosphate can be synthesized by phosphorylation of combretastatin A-4 (I) following several related strategies. Direct phosphorylation of (I) employing either bis(2,2,2-trichloroethyl) phosphorochloridate in pyridine (1,2) or dibenzyl phosphite in the presence of CCl4 and DMAP (3-5) furnishes the corresponding bis-trichloroethyl (IIa) and dibenzyl (IIb) phosphate esters, which are subsequently deprotected to combretastatin A-4 phosphate (III) by either reductive trichloroethyl group cleavage with zinc dust and acetic acid (1,2) or by debenzylation with chlorotrimethylsilane/sodium iodide (3-5). Alternatively, phosphitylation of (I) using di-tert-butyl N,N- diethylphosphoramidite (3,4,6) or bis(trimethylsilylethyl) N,N-diisopropylphosphoramidite (3-5) in the presence of tetrazole yields the phosphite esters (IVa) and (IVb), respectively, which are further oxidized to the corresponding phosphates (Va) and (Vb) using m-chloroperbenzoic acid in CH2Cl2/THF (3-6). Combretastatin A-4 phosphate (III) is then obtained by acidic cleavage of the tert-butyl ester (Va) with trifluoroacetic acid (3,4,6) or trifluoromethanesulfonic acid (6), or by tetrabutylammonium fluoride-promoted cleavage of the trimethylsilylethyl ester (Vb) (3-5).