Patent ID: 8853147

Claim:
A method for repressing metastasis of a cancer, comprising administering to a subject in need thereof a therapeutically effective amount of a peptide epoxyketone proteasome inhibitor or a pharmaceutically acceptable salt thereof, wherein the proteasome inhibitor has a structure of formula (I) or a pharmaceutically acceptable salt thereof wherein R 1 , R 2 , and R 3 are each independently selected from C 1-6 alkyl, C 1-6 hydroxyalkyl, C 1-6 alkoxyalkyl, aryl, and C 1-6 aralkyl, any of which is optionally substituted; R 4 is N(R 5 )L-Z—R 6 ; R 5 is selected from hydrogen, OH, C 1-6 aralkyl-Y—, and C 1-6 alkyl-Y—; R 6 is selected from hydrogen, OR 7 , C 1-6 alkenyl, Ar—Y—, carbocyclyl, and heterocyclyl; R 7 and R 8 are independently selected from hydrogen, C 1-6 alkyl, and C 1-6 aralkyl; each Ar is independently an aromatic or heteroaromatic group optionally substituted with 1-4 substituents; L is selected from C═O, C═S, and SO 2 ; X is selected from O, S, NH, and N—C 1-6 alkyl; Y is absent or is selected from C═O and SO 2 ; and Z is absent or is C 1-6 alkyl.