Purity >98% by NMR, TLC. Carfilzomib is a potent and irreversible proteasome inhibitor. Synthetic analog of the microbial product epoxomcin. Compared to bortezomib it displays equal potency but greater selectivity for the chymotrypsin-like activity of the proteasome. In cell culture it is more cytotoxic than bortezomib and hematologic tumor cells exhibit greater sensitivity than solid tumor cells. Treatment of cells with carfilzomib results in the accumulation of proteasome substrates and induction of cell cycle arrest and/or apoptosis. Effective against multiple myeloma. Active in vivo.