Abstract:
The invention provides a method of repressing metastasis of a cancer compromising the administration of a peptide epoxyketone proteasome inhibitor. Furthermore, the method can be performed in combination with the administration of one or more additional therapeutics.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is the U.S. national stage under 35 USC §371 of International Application Number PCT/US2010/056395, filed on 11 Nov. 2010, which claims the benefit of U.S. Provisional Application No. 61/261,062, filed on 13 Nov. 2009, the entire contents of each of these prior applications is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Metastasis is the spread of a disease from one organ or part to another non-adjacent organ or part. It is commonly associated with cancer, where cancer cells migrate from the place where the cancer started (the “primary tumor”) to other parts parts of the body to form a new tumor. The new tumor is a “metastic” or “secondary” tumor of the primary tumor. Thus, if breast cancer cells metastasize to the lungs, the secondary tumor is called metastatic breast cancer, not lung cancer. Most tumors and other neoplasms can metastasize; thus, the clinical management of metastasis is of great importance. 
     An extraordinarily complex process, metastasis consists of a series of important steps. These steps include detachment of tumor cells from the primary tumor, invasion through surrounding tissues and basement membranes, entry and survival in the circulation, lymphatic system or peritoneal space, and establishment and proliferation of the tumor cells in a distant target organ. The specific molecular mechanisms behind these steps remain unclear, thus, identifying effective methods to prevent or suppress tumor metastasis has been challenging. New methods are needed. 
     SUMMARY OF THE INVENTION 
     While having a general function in intracellular protein turnover, the proteasome controls the levels of proteins that are important for cell-cycle progression and apoptosis in normal and malignant cells, for example, cyclins, caspases, BCL-2 and nF-kB (Kumatori et al., Proc. Natl. Acad. Sci. USA (1990) 87:7071-7075; Almond et al., Leukemia (2002) 16: 433-443). Many of these proteins are key components in the steps involved in the metastatic process. Therefore, inhibiting proteasome activity can translate into therapies to treat various disease states, such as the prevention or repression of metastic tumors. 
     In certain embodiments, the present invention relates to methods for repressing or preventing the metastatic spread of cancer, comprising administering a peptide epoxyketone proteasome inhibitor. In certain such embodiments, the peptide epoxyketone proteasome inhibitor is a tripeptide epoxyketone. 
     The peptide epoxyketone may be administered by any of various modes. In certain embodiments, the peptide epoxyketone is administered orally. 
     In certain embodiments of the present invention, the peptide epoxyketone proteasome inhibitor may be used in combination with other therapeutic agents. The additional therapeutics may be known at the time of this application, or may become apparent after the date of this application. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  shows a reduction in the number of metastatic breast tumors with the administration of Compound 1. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In certain embodiments, the invention relates to a method to repress or prevent the metastasis of a cancer in an individual, comprising administering a peptide epoxy ketone. In some embodiments, the individual is a mammal. In certain preferred embodiments the individual is a human. 
     In certain embodiments, the peptide epoxyketone has a structure of formula (I) or a pharmaceutically acceptable salt thereof, 
                                
wherein
     each Ar is independently an aromatic or heteroaromatic group optionally substituted with 1 to 4 substituents;   L is absent or is selected from C═O, C═S, and SO 2 , preferably SO 2  or C═O;   X is selected from O, S, NH, and N—C 1-6 alkyl, preferably O;   Y is absent or is selected from C═O and SO 2 ;   Z is absent or is C 1-6 alkyl;   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—, preferably hydrogen;   R 6  is selected from hydrogen, OR 7 , C 1-6 alkenyl, Ar—Y—, carbocyclyl, and heterocyclyl; and   R 7  and R 8  are independently selected from hydrogen, C 1-6 alkyl, and C 1-6 aralkyl, preferably hydrogen.   

     In certain embodiments, L is selected from C═O, C═S, and SO 2 , preferably SO 2  or C═O. 
     In certain embodiments, R 5  is selected from hydrogen, OH, C 1-6 aralkyl, and C 1-6 alkyl, preferably hydrogen. 
     In certain embodiments, R 6  is selected from hydrogen, C 1-6 alkenyl, Ar—Y—, carbocyclyl, and heterocyclyl. 
     In certain embodiments, X is O and R 1 , R 2 , and R 3  are each independently selected from C 1-6 alkyl, C 1-6 hydroxyalkyl, and C 1-6 aralkyl. In preferred such embodiments, R 1  and R 3  are independently C 1-6 alkyl and R 2  is C 1-6 aralkyl. In more preferred such embodiments, R 1  and R 3  are both isobutyl and R 2  is phenylmethyl. 
     In certain embodiments, R 5  is hydrogen, L is C═O or SO 2 , R 6  is Ar—Y—, and each Ar is independently selected from phenyl, indolyl, benzofuranyl, naphthyl, quinolinyl, quinolonyl, thienyl, pyridyl, pyrazyl, and the like. In certain such embodiments, Ar may be substituted with Ar-Q—, where Q is selected from a direct bond, —O—, and C 1-6 alkyl. In certain other such embodiments where Z is C 1-6 alkyl, Z may be substituted, preferably with Ar, e.g., phenyl. 
     In certain embodiments, R 5  is hydrogen, Z is absent, L is C═O or SO 2 , and R 6  is selected from Ar—Y and heterocyclyl. In certain preferred such embodiments, heterocyclyl is selected from chromonyl, chromanyl, morpholino, and piperidinyl. In certain other preferred such embodiments, Ar is selected from phenyl, indolyl, benzofuranyl, naphthyl, quinolinyl, quinolonyl, thienyl, pyridyl, pyrazyl, and the like. 
     In certain embodiments, R 5  is hydrogen, L is C═O or SO 2 , Z is absent, and R 6  is C 1-6 alkenyl, where C 1-6 alkenyl is a substituted vinyl group where the substituent is preferably an aryl or heteroaryl group, more preferably a phenyl group optionally substituted with one to four substituents. 
     In certain embodiments, R 2  and R 8  are independently selected from hydrogen and C 1-6 alkyl. In certain preferred such embodiments, R 2  and R 8  are independently selected from hydrogen and methyl. In more preferred such embodiments, R 2  and R 8  are both hydrogen. 
     In certain alternative embodiments, the peptide epoxyketone has a structure of Formula (II) or a pharmaceutically acceptable salt thereof: 
     
       
                 
         
             
             
         
      
     
     wherein 
     L is selected from C═O, C═S, and SO 2 , preferably C═O; 
     X is O; 
     Z is absent, C 1-6 alkyl, or C 1-6 alkoxy, preferably absent; 
     R 1 , R 2 , and R 3  are each independently selected from hydrogen, C 1-6 alkyl, C 1-6 alkenyl, C 1-6 hydroxyalkyl, C 1-6 alkoxyalkyl, aryl, C 1-6 aralkyl, heteroaryl, heterocyclyl, C 1-6 heterocycloalkyl, C 1-6 heteroaralkyl, carbocyclyl, and C 1-6 carbocyclolalkyl; 
     R 4  is selected from hydrogen, C 1-6 aralkyl, and C 1-6 alkyl; 
     R 5  is heteroaryl; and 
     R 6  and R 2  are independently selected from hydrogen, C 1-6 alkyl, and C 1-6 aralkyl. 
     In certain embodiments, R 1 , R 2 , and R 3  are independently selected from hydrogen, C 1-6 alkyl, C 1-6 hydroxyalkyl, C 1-6 alkoxyalkyl, C 1-6 heterocycloalkyl, C 1-6 heteroaralkyl, and C 1-6 -carbocyclolalkyl. In certain embodiments, any of R 1 , R 2 , and R 3  are independently C 1-6 alkyl selected from methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, and isobutyl. In certain embodiments, any of R 1 , R 2 , and R 3  are independently C 1-6 hydroxyalkyl. In certain preferred such embodiments, any of R 1 , R 2 , and R 3  are independently selected from hydroxymethyl and hydroxyethyl, preferably hydroxymethyl. In certain embodiments, any of R 1 , R 2 , and R 3  are independently C 1-6 alkoxyalkyl. In certain such embodiments, any of R 1 , R 2 , and R 3  are independently selected from methoxymethyl and methoxyethyl, preferably methoxymethyl. In certain embodiments, any of R 1 , R 2 , and R 3  are independently C 1-6 heteroaralkyl. In certain such embodiments, any of R 1 , R 2 , and R 3  are independently selected from imidazolylmethyl, pyrazolylmethyl, and thiazolylmethyl, and pyridylmethyl, preferably imidazol-4-ylmethyl, thiazol-4-ylmethyl, 2-pyridylmethyl, 3-pyridylmethyl, or 4-pyridylmethyl. In certain embodiments, any of R 1 , R 2 , and R 3  are independently C 1-6 aralkyl. In certain such embodiments, any of R 1 , R 2 , and R 3  are independently selected from phenylmethyl (benzyl) and phenylethyl, preferably phenylmethyl. In certain embodiments, any of R 1 , R 2 , and R 3  are independently C 1-6 carbocycloalkyl. In certain such embodiments, R 1  is cyclohexylmethyl. In certain embodiments R 1 , R 2 , and R 3  are all different. In certain embodiments, any two of R 1 , R 2 , and R 3  are the same. In certain embodiments, R 1 , R 2 , and R 3  are all the same. 
     In certain embodiments, at least one of R 1  and R 2  is selected from C 1-6 hydroxyalkyl and C 1-6 alkoxyalkyl. In certain such embodiments, at least one of R 1  and R 2  is alkoxyalkyl. In certain such embodiments, at least one of R 1  and R 2  is selected from methoxymethyl and methoxyethyl. 
     In certain embodiments, R 3  is selected from C 1-6 alkyl and C 1-6 aralkyl, preferably C 1-6 alkyl. In certain such embodiments, R 3  is selected from methyl, ethyl, isopropyl, sec-butyl, and isobutyl. In certain such embodiments, R 3  is isobutyl. In certain alternative embodiments, R 3  is selected from phenylmethyl and phenylethyl, preferably phenylmethyl. 
     In certain embodiments, R 4 , R 6 , and R 7  are independently selected from hydrogen and methyl, preferably hydrogen. 
     In certain embodiments, R 5  is a 5- or 6-membered heteroaryl. In certain such embodiments, R 5  is selected from isoxazole, isothiazole, furan, thiophene, oxazole, thiazole, pyrazole, or imidazole, preferably isoxazole, furan, or thiazole. 
     In certain embodiments, R 5  is a bicyclic heteroaryl. In certain such embodiments, bicyclic heteroaryl is selected from benzisoxazole, benzoxazole, benzothiazole, benzisothiazole. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is an isoxazol-3-yl or isoxazol-5-yl. In certain preferred such embodiments, when the isoxazol-3-yl is substituted, it is substituted at least at the 5-position. In certain preferred embodiments, when the isoxazol-5-yl is substituted, it is substituted at least at the 3-position. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is an unsubstituted isoxazol-3-yl. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is a substituted isoxazol-3-yl. In certain such embodiments, R 5  is isoxazol-3-yl substituted with a substituent selected from C 1-6 alkyl, C 1-6 alkoxy, C 1-6 alkoxyalkyl, C 1-6 hydroxyalkyl, carboxylic acid, aminocarboxylate, C 1-6 alkylaminocarboxylate, (C 1-6 alkyl) 2 aminocarboxylate, C 1-6 alkylcarboxylate, C 1-6 heteroaralkyl, C 1-6 aralkyl, C 1-6 heterocycloalkyl, and C 1-6 carbocycloalkyl. In certain preferred such embodiments, R 5  is isoxazole-3-yl substituted with a substituent selected from methyl, ethyl, isopropyl, and cyclopropylmethyl. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is isoxazol-3-yl substituted with a 4- to 6-membered nitrogen-containing C 1-6 heterocycloalkyl. In certain such embodiments, R 5  is isoxazol-3-yl substituted with azetidinylmethyl, preferably azetidin-1-ylmethyl. In certain alternative such embodiments, L is C═O, Z is absent, and R 5  is isoxazol-3-yl substituted with 
                                
wherein W is O, NR, or CH 2 , and R is H or C 1-6 alkyl. In certain such embodiments, W is O.
 
     In certain embodiments, L is C═O, Z is absent, and R 5  is isoxazol-3-yl substituted with 5-membered nitrogen-containing C 1-6 heteroaralkyl, such as pyrazolylmethyl, imidazolylmethyl, triazol-5-ylmethyl, preferably 1,2,4-triazol-5-ylmethyl. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is isoxazol-3-yl substituted with C 1-6 alkoxy or C 1-6 alkoxyalkyl, preferably methoxy, ethoxy, methoxymethyl, or methoxyethyl. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is isoxazol-3-yl substituted with C 1-6 hydroxyalkyl, preferably hydroxymethyl or hydroxyethyl. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is isoxazol-3-yl substituted with a carboxylic acid, aminocarboxylate, C 1-6 alkylaminocarboxylate, (C 1-6 alkyl) 2 aminocarboxylate, or C 1-6 alkylcarboxylate. In certain such embodiments, R 5  is substituted with methyl carboxylate or ethyl carboxylate, preferably methyl carboxylate. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is an unsubstituted isoxazol-5-yl. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is a substituted isoxazol-5-yl. In certain such embodiments, R 5  is isoxazol-5-yl substituted with a substituent selected from C 1-6 alkyl, C 1-6 alkoxy, C 1-6 alkoxyalkyl, C 1-6 hydroxyalkyl, carboxylic acid, aminocarboxylate, C 1-6 alkylaminocarboxylate, (C 1-6 alkyl) 2 aminocarboxylate, C 1-6 alkylcarboxylate, C 1-6 heteroaralkyl, C 1-6 heterocycloalkyl, and C 1-6 carbocycloalkyl. In certain preferred such embodiments, R 5  is isoxazole-3-yl substituted with a substituent selected from methyl, ethyl, isopropyl, and cyclopropylmethyl. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is isoxazol-3-yl substituted with a 4- to 6-membered nitrogen-containing C 1-6 heterocycloalkyl. In certain such embodiments, R 5  is isoxazol-5-yl substituted with azetidinylmethyl, preferably azetidin-1-ylmethyl. In certain alternative such embodiments, L is C═O, Z is absent, and R 5  is isoxazol-3-yl substituted with 
                                
wherein W is O, NR, or CH 2 , and R is H or C 1-6 alkyl. In certain such embodiments, W is O.
 
     In certain embodiments, L is C═O, Z is absent, and R 5  is isoxazol-5-yl substituted with 5-membered nitrogen-containing C 1-6 heteroaralkyl, such as pyrazolylmethyl, imidazolylmethyl, triazol-5-ylmethyl, preferably 1,2,4-triazol-5-ylmethyl. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is isoxazol-5-yl substituted with C 1-6 alkoxy or C 1-6 alkoxyalkyl, preferably methoxy, ethoxy, methoxymethyl, or methoxyethyl. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is isoxazol-5-yl substituted with C 1-6 hydroxyalkyl, preferably hydroxymethyl or hydroxyethyl. 
     In certain embodiments, L is C═O, Z is absent, and R 5  is isoxazol-3-yl substituted with a carboxylic acid, aminocarboxylate, C 1-6 alkylaminocarboxylate, (C 1-6 alkyl) 2 aminocarboxylate, or C 1-6 alkylcarboxylate. In certain such embodiments, R 5  is substituted with methyl carboxylate or ethyl carboxylate, preferably methyl carboxylate. 
     In certain preferred embodiments, a compound of Formula (II) has a structure 
     
       
                 
         
             
             
         
      
     
     DEFINITIONS 
     The term “C x-y alkyl” refers to substituted or unsubstituted saturated hydrocarbon groups, including straight-chain alkyl and branched-chain alkyl groups that contain from x to y carbons in the chain, including haloalkyl groups such as trifluoromethyl and 2,2,2-trifluoroethyl, etc. C 0 alkyl indicates a hydrogen where the group is in a terminal position, a bond if internal. The terms “C 2-y alkenyl” and “C 2-y alkynyl” refer to substituted or unsubstituted unsaturated aliphatic groups analogous in length and possible substitution to the alkyls described above, but that contain at least one double or triple bond respectively. 
     The term “alkoxy” refers to an alkyl group having an oxygen attached thereto. Representative alkoxy groups include methoxy, ethoxy, propoxy, tert-butoxy and the like. 
     An “ether” is two hydrocarbons covalently linked by an oxygen. Accordingly, the substituent of an alkyl that renders that alkyl an ether is or resembles an alkoxy. 
     The term “C 1-6 alkoxyalkyl” refers to a C 1-6 alkyl group substituted with an alkoxy group, thereby forming an ether. 
     The term “C 1-6 aralkyl”, as used herein, refers to a C 1-6 alkyl group substituted with an aryl group. 
     The terms “amine” and “amino” are art-recognized and refer to both unsubstituted and substituted amines and salts thereof, e.g., a moiety that can be represented by the general formulae: 
                                
wherein R 9 , R 10  and R 10′  each independently represent a hydrogen, an alkyl, an alkenyl, —(CH 2 ) m —R 8 , or R 9  and R 10  taken together with the N atom to which they are attached complete a heterocycle having from 4 to 8 atoms in the ring structure; R 8  represents an aryl, a cycloalkyl, a cycloalkenyl, a heterocyclyl or a polycyclyl; and m is zero or an integer from 1 to 8. In preferred embodiments, only one of R 9  or R 10  can be a carbonyl, e.g., R 9 , R 10 , and the nitrogen together do not form an imide. In even more preferred embodiments, R 9  and R 10  (and optionally R 10′ ) each independently represent a hydrogen, an alkyl, an alkenyl, or —(CH 2 ) m —R 8 . In certain embodiments, the amino group is basic, meaning the protonated form has a pK a ≧7.00.
 
     The terms “amide” and “amido” are art-recognized as an amino-substituted carbonyl and includes a moiety that can be represented by the general formula: 
                                
wherein R 9 , R 10  are as defined above. Preferred embodiments of the amide will not include imides which may be unstable.
 
     The term “aryl” as used herein includes 5-, 6-, and 7-membered substituted or unsubstituted single-ring aromatic groups in which each atom of the ring is carbon. The term “aryl” also includes polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is aromatic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls. Aryl groups include benzene, naphthalene, phenanthrene, phenol, aniline, and the like. 
     The terms “carbocycle” and “carbocyclyl”, as used herein, refer to a non-aromatic substituted or unsubstituted ring in which each atom of the ring is carbon. The terms “carbocycle” and “carbocyclyl” also include polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is carbocyclic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls. 
     The term “carbonyl” is art-recognized and includes such moieties as can be represented by the general formula: 
                                
wherein X is a bond or represents an oxygen or a sulfur, and R 11  represents a hydrogen, an alkyl, an alkenyl, —(CH 2 ) m —R 8  or a pharmaceutically acceptable salt, R 11′  represents a hydrogen, an alkyl, an alkenyl or —(CH 2 ) m —R 8 , where m and R 8  are as defined above. Where X is an oxygen and R 11  or R 11′  is not hydrogen, the formula represents an “ester”. Where X is an oxygen, and R 11  is a hydrogen, the formula represents a “carboxylic acid”.
 
     As used herein, “enzyme” can be any partially or wholly proteinaceous molecule which carries out a chemical reaction in a catalytic manner. Such enzymes can be native enzymes, fusion enzymes, proenzymes, apoenzymes, denatured enzymes, farnesylated enzymes, ubiquitinated enzymes, fatty acylated enzymes, gerangeranylated enzymes, GPI-linked enzymes, lipid-linked enzymes, prenylated enzymes, naturally-occurring or artificially-generated mutant enzymes, enzymes with side chain or backbone modifications, enzymes having leader sequences, and enzymes complexed with non-proteinaceous material, such as proteoglycans, proteoliposomes. Enzymes can be made by any means, including natural expression, promoted expression, cloning, various solution-based and solid-based peptide syntheses, and similar methods known to those of skill in the art. 
     The term “C 1-6 heteroaralkyl”, as used herein, refers to a C 1-6 alkyl group substituted with a heteroaryl group. 
     The terms “heteroaryl” includes substituted or unsubstituted aromatic 5- to 7-membered ring structures, more preferably 5- to 6-membered rings, whose ring structures include one to four heteroatoms. The term “heteroaryl” also includes polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is heteroaromatic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls. Heteroaryl groups include, for example, pyrrole, furan, thiophene, imidazole, isoxazole, oxazole, thiazole, triazole, pyrazole, pyridine, pyrazine, pyridazine and pyrimidine, and the like. 
     The term “heteroatom” as used herein means an atom of any element other than carbon or hydrogen. Preferred heteroatoms are nitrogen, oxygen, phosphorus, and sulfur. 
     The terms “heterocyclyl” or “heterocyclic group” refer to substituted or unsubstituted non-aromatic 3- to 10-membered ring structures, more preferably 3- to 7-membered rings, whose ring structures include one to four heteroatoms. The term terms “heterocyclyl” or “heterocyclic group” also include polycyclic ring systems having two or more cyclic rings in which two or more carbons are common to two adjoining rings wherein at least one of the rings is heterocyclic, e.g., the other cyclic rings can be cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls. Heterocyclyl groups include, for example, tetrahydrofuran, piperidine, piperazine, pyrrolidine, morpholine, lactones, lactams, and the like. 
     The term “C 1-6 heterocycloalkyl”, as used herein, refers to a C 1-6 alkyl group substituted with a heterocyclyl group. 
     The term “C 1-6 hydroxyalkyl” refers to a C 1-6 alkyl group substituted with a hydroxy group. 
     As used herein, the term “inhibitor” is meant to describe a compound that blocks or reduces an activity of an enzyme (for example, inhibition of proteolytic cleavage of standard fluorogenic peptide substrates, inhibition of various catalytic activities of the 20S proteasome). An inhibitor can act with competitive, uncompetitive, or noncompetitive inhibition. An inhibitor can bind reversibly or irreversibly, and therefore the term includes compounds that are suicide substrates of an enzyme. An inhibitor can modify one or more sites on or near the active site of the enzyme, or it can cause a conformational change elsewhere on the enzyme. 
     As used herein, the term “peptide” includes not only standard amide linkage with standard α-substituents, but commonly utilized peptidomimetics, other modified linkages, non-naturally occurring side chains, and side chain modifications, as detailed below. 
     The terms “polycyclyl” or “polycyclic” refer to two or more rings (e.g., cycloalkyls, cycloalkenyls, cycloalkynyls, aryls, heteroaryls, and/or heterocyclyls) in which two or more carbons are common to two adjoining rings, e.g., the rings are “fused rings”. Each of the rings of the polycycle can be substituted or unsubstituted. 
     The term “preventing” is art-recognized, and when used in relation to a condition, such as a local recurrence (e.g., pain), a disease such as cancer, a syndrome complex such as heart failure or any other medical condition, is well understood in the art, and includes administration of a composition which reduces the frequency of, or delays the onset of, symptoms of a medical condition in a subject relative to a subject which does not receive the composition. Thus, prevention of cancer includes, for example, reducing the number of detectable cancerous growths in a population of patients receiving a prophylactic treatment relative to an untreated control population, and/or delaying the appearance of detectable cancerous growths in a treated population versus an untreated control population, e.g., by a statistically and/or clinically significant amount. Prevention of an infection includes, for example, reducing the number of diagnoses of the infection in a treated population versus an untreated control population, and/or delaying the onset of symptoms of the infection in a treated population versus an untreated control population. Prevention of pain includes, for example, reducing the magnitude of, or alternatively delaying, pain sensations experienced by subjects in a treated population versus an untreated control population. 
     The term “prodrug” encompasses compounds that, under physiological conditions, are converted into therapeutically active agents. A common method for making a prodrug is to include selected moieties that are hydrolyzed under physiological conditions to reveal the desired molecule. In other embodiments, the prodrug is converted by an enzymatic activity of the host animal. 
     The term “prophylactic or therapeutic” treatment is art-recognized and includes administration to the host of one or more of the subject compositions. If it is administered prior to clinical manifestation of the unwanted condition (e.g., disease or other unwanted state of the host animal) then the treatment is prophylactic, (i.e., it protects the host against developing the unwanted condition), whereas if it is administered after manifestation of the unwanted condition, the treatment is therapeutic, (i.e., it is intended to diminish, ameliorate, or stabilize the existing unwanted condition or side effects thereof). 
     The term “proteasome” as used herein is meant to include immuno- and constitutive proteasomes. 
     The term “repressing” is art-recognized, and when used in relation to a condition, such as cancer or any other medical condition, is well understood in the art, and includes administration of a composition which reduces the frequency of, or delays the onset of, symptoms of a medical condition in a subject relative to a subject which does not receive the composition. Thus, repression of metastasis includes, for example, reducing the number of detectable metastatic cancerous growths in a population of patients receiving a prophylactic treatment relative to an untreated control population, and/or delaying the appearance of detectable metastatic cancerous growths in a treated population versus an untreated control population, e.g., by a statistically and/or clinically significant amount. 
     The term “substituted” refers to moieties having substituents replacing a hydrogen on one or more carbons of the backbone. It will be understood that “substitution” or “substituted with” includes the implicit proviso that such substitution is in accordance with permitted valence of the substituted atom and the substituent, and that the substitution results in a stable compound, e.g., which does not spontaneously undergo transformation such as by rearrangement, cyclization, elimination, etc. As used herein, the term “substituted” is contemplated to include all permissible substituents of organic compounds. In a broad aspect, the permissible substituents include acyclic and cyclic, branched and unbranched, carbocyclic and heterocyclic, aromatic and non-aromatic substituents of organic compounds. The permissible substituents can be one or more and the same or different for appropriate organic compounds. For purposes of this invention, the heteroatoms such as nitrogen may have hydrogen substituents and/or any permissible substituents of organic compounds described herein which satisfy the valences of the heteroatoms. Substituents can include, for example, a halogen, a hydroxyl, a carbonyl (such as a carboxyl, an alkoxycarbonyl, a formyl, or an acyl), a thiocarbonyl (such as a thioester, a thioacetate, or a thioformate), an alkoxyl, a phosphoryl, a phosphate, a phosphonate, a phosphinate, an amino, an amido, an amidine, an imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety. It will be understood by those skilled in the art that the moieties substituted on the hydrocarbon chain can themselves be substituted, if appropriate. 
     A “therapeutically effective amount” of a compound with respect to the subject method of treatment, refers to an amount of the compound(s) in a preparation which, when administered as part of a desired dosage regimen (to a mammal, preferably a human) alleviates a symptom, ameliorates a condition, or slows the onset of disease conditions according to clinically acceptable standards for the disorder or condition to be treated or the cosmetic purpose, e.g., at a reasonable benefit/risk ratio applicable to any medical treatment. 
     The term “thioether” refers to an alkyl group, as defined above, having a sulfur moiety attached thereto. In preferred embodiments, the “thioether” is represented by —S-alkyl. Representative thioether groups include methylthio, ethylthio, and the like. 
     As used herein, the term “treating” or “treatment” includes reversing, reducing, or arresting the symptoms, clinical signs, and underlying pathology of a condition in manner to improve or stabilize a subject&#39;s condition. 
     Metastic Cancers 
     In accordance with the invention, a peptide epoxyketone or a pharmaceutically acceptable salt thereof can be used in the repression of metastasis of a cancer, including but not limited to hematological malignancies, solid tumors, neuroblastoma, or melanoma. 
     In some embodiments of the invention, administration of the proteasome inihibitor is initiated after a metastic tumor has been identified. In other embodiments of the invention, administration of the proteasome inihibitor is initiated after a primary cancer tumor has been identified. In certain preferred embodiments, administration of the proteasome inihibitor is initiated after a primary tumor is identified, but prior to the detection of a metastatic tumor. In certain embodiments of the invention, the proteasome inhibitor is administered prophylactically to an individual susceptible to a metstatic cancer. 
     In certain embodiments, the cancer is a hematological cancer selected from diffuse large B-cell lymphoma (DLBCL), T-cell lymphomas or leukemias (e.g., cutaneous T-cell lymphoma (CTCL), noncutaneous peripheral T-cell lymphoma, lymphoma associated with human T-cell lymphotrophic virus (HTLV), and adult T-cell leukemia/lymphoma (ATLL)), acute lymphocytic leukemia, acute myelogenous leukemia (e.g., acute monocytic leukemia and acute promyelocytic leukemia), chronic lymphocytic leukemia (e.g., chronic B cell leukemia), chronic myelogenous leukemia, Hodgkin&#39;s disease, non-Hodgkin&#39;s lymphoma (e.g., Burkitt&#39;s lymphoma), myeloma, multiple myeloma, and myelodysplastic syndrome. In certain embodiments, the cancer is multiple myeloma. In certain embodiments, the cancer is a lymphoma. 
     In certain embodiments the cancer is a solid tumor, neuroblastoma, or melanoma selected from mesothelioma, brain neuroblastoma, retinoblastoma, glioma, Wilms&#39; tumor, bone cancer and soft-tissue sarcomas, head and neck cancers (e.g., oral, laryngeal and esophageal), genitourinary cancers (e.g., prostate, bladder, renal, uterine, ovarian, testicular, rectal, colorectal and colon), lung cancer (e.g., small cell carcinoma and non-small cell lung carcinoma, including squamous cell carcinoma and adenocarcinoma), breast cancer, pancreatic cancer, basal cell carcinoma, metastatic skin carcinoma, squamous cell carcinoma (both ulcerating and papillary type), stomach cancer, brain cancer, liver cancer, adrenal cancer, kidney cancer, thyroid cancer, medullary carcinoma, osteosarcoma, soft-tissue sarcoma, Ewing&#39;s sarcoma, reticulum cell sarcoma, and Kaposi&#39;s sarcoma. In certain embodiments, the cancer is selected from breast cancer, cervical cancer, colorectal cancer, kidney cancer, lung cancer, melanoma, ovarian cancer (e.g., ovarian adenocarcinoma), pancreatic cancer and prostate cancer. 
     In certain embodiments, the cancer is selected from breast, cervical, colorectal, hematologic, kidney, lung, melanoma, nuerological, pancreatic and prostate cancer. 
     Also included are pediatric forms of any of the cancers described herein. This invention also provides a method for the treatment of drug resistant tumors. In certain embodiments, the drug resistant tumor is multiple myeloma. In other embodiments, the drug resistant tumor is a solid tumor. 
     The term “drug resistant” as used herein refers to a condition which demonstrates intrinsic resistance or acquired resistance. 
     The term “intrinsic resistance” as used herein refers to the characteristic expression profile in cancer cells of key genes in relevant pathways, including but not limited to apoptosis, cell progression and DNA repair, which contributes to the more rapid growth ability of cancerous cells when compared to their normal counterparts. 
     The term “acquired resistance” as used herein refers to a multifactorial phenomenon occurring in tumor formation and progression that can influence the sensitivity of cancer cells to a drug. Acquired resistance may be due to several mechanisms such as but not limited to: alterations in drug-targets, decreased drug accumulation, alteration of intracellular drug distribution, reduced drug-target interaction, increased detoxification response, cell-cycle deregulation, increased damaged-DNA repair, and reduced apoptotic response. Several of these mechanisms may occur simultaneously and/or may interact with each other. Their activation and/or inactivation can be due to genetic or epigenetic events or to the presence of oncoviral proteins. Acquired resistance may occur to individual drugs but can also occur more broadly to many different drugs with different chemical structures and different mechanisms of action. This form of resistance is referred to as multidrug resistance. 
     Administration of the Peptide Epoxyketone Proteasome Inhibitor 
     The peptide epoxyketone proteasome inhibitors as described herein can be administered in various forms, depending on the disorder to be treated and the age, condition, and body weight of the patient, as is well known in the art. For example, where the compounds are to be administered orally, they may be formulated as tablets, capsules, granules, powders, or syrups; or for parenteral administration, they may be formulated as injections (intravenous, intramuscular, or subcutaneous), drop infusion preparations, or suppositories. For application by the ophthalmic mucous membrane route, they may be formulated as eye drops or eye ointments. These formulations can be prepared by conventional means, and if desired, the active ingredient may be mixed with any conventional additive or excipient, such as a binder, a disintegrating agent, a lubricant, a corrigent, a solubilizing agent, a suspension aid, an emulsifying agent, a coating agent, a cyclodextrin, and/or a buffer. Although the dosage will vary depending on the symptoms, age and body weight of the patient, the nature and severity of the disorder to be treated or prevented, the route of administration and the form of the drug, in general, a daily dosage of from 0.01 to 2000 mg of the compound is recommended for an adult human patient, and this may be administered in a single dose or in divided doses. The amount of active ingredient which can be combined with a carrier material to produce a single dosage form will generally be that amount of the compound which produces a therapeutic effect. 
     The precise time of administration and/or amount of the composition that will yield the most effective results in terms of efficacy of treatment in a given patient will depend upon the activity, pharmacokinetics, and bioavailability of a particular compound, physiological condition of the patient (including age, sex, disease type and stage, general physical condition, responsiveness to a given dosage, and type of medication), route of administration, etc. However, the above guidelines can be used as the basis for fine-tuning the treatment, e.g., determining the optimum time and/or amount of administration, which will require no more than routine experimentation consisting of monitoring the subject and adjusting the dosage and/or timing. 
     The phrase “pharmaceutically acceptable” is employed herein to refer to those ligands, materials, compositions, and/or dosage forms which are, within the scope of sound medical judgment, suitable for use in contact with the tissues of human beings and animals without excessive toxicity, irritation, allergic response, or other problem or complication, commensurate with a reasonable benefit/risk ratio. 
     The phrase “pharmaceutically acceptable carrier” as used herein means a pharmaceutically acceptable material, composition, or vehicle, such as a liquid or solid filler, diluent, excipient, solvent or encapsulating material. Each carrier must be “acceptable” in the sense of being compatible with the other ingredients of the formulation and not injurious to the patient. Some examples of materials which can serve as pharmaceutically acceptable carriers include: (1) sugars, such as lactose, glucose, and sucrose; (2) starches, such as corn starch, potato starch, and substituted or unsubstituted β-cyclodextrin; (3) cellulose, and its derivatives, such as sodium carboxymethyl cellulose, ethyl cellulose, and cellulose acetate; (4) powdered tragacanth; (5) malt; (6) gelatin; (7) talc; (8) excipients, such as cocoa butter and suppository waxes; (9) oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil, olive oil, corn oil, and soybean oil; (10) glycols, such as propylene glycol; (11) polyols, such as glycerin, sorbitol, mannitol, and polyethylene glycol; (12) esters, such as ethyl oleate and ethyl laurate; (13) agar; (14) buffering agents, such as magnesium hydroxide and aluminum hydroxide; (15) alginic acid; (16) pyrogen-free water; (17) isotonic saline; (18) Ringer&#39;s solution; (19) ethyl alcohol; (20) phosphate buffer solutions; and (21) other non-toxic compatible substances employed in pharmaceutical formulations. In certain embodiments, pharmaceutical compositions of the present invention are non-pyrogenic, i.e., do not induce significant temperature elevations when administered to a patient. 
     The term “pharmaceutically acceptable salt” refers to the relatively non-toxic, inorganic and organic acid addition salts of the inhibitor(s). These salts can be prepared in situ during the final isolation and purification of the inhibitor(s), or by separately reacting a purified inhibitor(s) in its free base form with a suitable organic or inorganic acid, and isolating the salt thus formed. Representative salts include the hydrobromide, hydrochloride, sulfate, bisulfate, phosphate, nitrate, acetate, valerate, oleate, palmitate, stearate, laurate, benzoate, lactate, phosphate, tosylate, citrate, maleate, fumarate, succinate, tartrate, naphthylate, mesylate, glucoheptonate, lactobionate, laurylsulphonate salts, and amino acid salts, and the like. (See, for example, Berge et al. (1977) “Pharmaceutical Salts”, J. Pharm. Sci. 66: 1-19.) 
     In other embodiments, the peptide epoxyketone proteasome inhibitors useful in the methods of the present invention may contain one or more acidic functional groups and, thus, are capable of forming pharmaceutically acceptable salts with pharmaceutically acceptable bases. The term “pharmaceutically acceptable salts” in these instances refers to the relatively non-toxic inorganic and organic base addition salts of an inhibitor(s). These salts can likewise be prepared in situ during the final isolation and purification of the inhibitor(s), or by separately reacting the purified inhibitor(s) in its free acid form with a suitable base, such as the hydroxide, carbonate, or bicarbonate of a pharmaceutically acceptable metal cation, with ammonia, or with a pharmaceutically acceptable organic primary, secondary, or tertiary amine. Representative alkali or alkaline earth salts include the lithium, sodium, potassium, calcium, magnesium, and aluminum salts, and the like. Representative organic amines useful for the formation of base addition salts include ethylamine, diethylamine, ethylenediamine, ethanolamine, diethanolamine, piperazine, and the like (see, for example, Berge et al., supra). 
     Wetting agents, emulsifiers, and lubricants, such as sodium lauryl sulfate and magnesium stearate, as well as coloring agents, release agents, coating agents, sweetening, flavoring, and perfuming agents, preservatives and antioxidants can also be present in the compositions. 
     Examples of pharmaceutically acceptable antioxidants include: (1) water soluble antioxidants, such as ascorbic acid, cysteine hydrochloride, sodium bisulfate, sodium metabisulfite, sodium sulfite, and the like; (2) oil-soluble antioxidants, such as ascorbyl palmitate, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), lecithin, propyl gallate, alpha-tocopherol, and the like; and (3) metal chelating agents, such as citric acid, ethylenediamine tetraacetic acid (EDTA), sorbitol, tartaric acid, phosphoric acid, and the like. 
     Formulations suitable for oral administration may be in the form of capsules, cachets, pills, tablets, lozenges (using a flavored basis, usually sucrose and acacia or tragacanth), powders, granules, or as a solution or a suspension in an aqueous or nonaqueous liquid, or as an oil-in-water or water-in-oil liquid emulsion, or as an elixir or syrup, or as pastilles (using an inert matrix, such as gelatin and glycerin, or sucrose and acacia) and/or as mouthwashes, and the like, each containing a predetermined amount of an inhibitor(s) as an active ingredient. A composition may also be administered as a bolus, electuary, or paste. 
     In solid dosage forms for oral administration (capsules, tablets, pills, dragees, powders, granules, and the like), the active ingredient may be mixed with one or more pharmaceutically acceptable carriers, such as sodium citrate or dicalcium phosphate, and/or any of the following: (1) fillers or extenders, such as starches, cyclodextrins, lactose, sucrose, glucose, mannitol, and/or silicic acid; (2) binders, such as, for example, carboxymethylcellulose, alginates, gelatin, polyvinyl pyrrolidone, sucrose, and/or acacia; (3) humectants, such as glycerol; (4) disintegrating agents, such as agar-agar, calcium carbonate, potato or tapioca starch, alginic acid, certain silicates, and sodium carbonate; (5) solution retarding agents, such as paraffin; (6) absorption accelerators, such as quaternary ammonium compounds; (7) wetting agents, such as, for example, acetyl alcohol and glycerol monostearate; (8) absorbents, such as kaolin and bentonite clay; (9) lubricants, such a talc, calcium stearate, magnesium stearate, solid polyethylene glycols, sodium lauryl sulfate, and mixtures thereof; and (10) coloring agents. In the case of capsules, tablets, and pills, the pharmaceutical compositions may also comprise buffering agents. Solid compositions of a similar type may also be employed as fillers in soft and hard-filled gelatin capsules using such excipients as lactose or milk sugars, as well as high molecular weight polyethylene glycols, and the like. In certain embodiments, the crystalline tripeptide epoxyketone is administered to a mammal as a capsule. In other embodiments, the crystalline tripeptide epoxyketone is a compound of formula (I). In more preferred embodiments, the crystalline tripeptide epoxyketone is a compound of formula (II). 
     A tablet may be made by compression or molding, optionally with one or more accessory ingredients. Compressed tablets may be prepared using binder (for example, gelatin or hydroxypropylmethyl cellulose), lubricant, inert diluent, preservative, disintegrant (for example, sodium starch glycolate or cross-linked sodium carboxymethyl cellulose), surface-active or dispersing agent. Molded tablets may be made by molding in a suitable machine a mixture of the powdered inhibitor(s) moistened with an inert liquid diluent. 
     Tablets, and other solid dosage forms, such as dragees, capsules, pills, and granules, may optionally be scored or prepared with coatings and shells, such as enteric coatings and other coatings well known in the pharmaceutical-formulating art. They may also be formulated so as to provide slow or controlled release of the active ingredient therein using, for example, hydroxypropylmethyl cellulose in varying proportions to provide the desired release profile, other polymer matrices, liposomes, and/or microspheres. They may be sterilized by, for example, filtration through a bacteria-retaining filter, or by incorporating sterilizing agents in the form of sterile solid compositions which can be dissolved in sterile water, or some other sterile injectable medium immediately before use. These compositions may also optionally contain opacifying agents and may be of a composition that they release the active ingredient(s) only, or preferentially, in a certain portion of the gastrointestinal tract, optionally, in a delayed manner. Examples of embedding compositions which can be used include polymeric substances and waxes. The active ingredient can also be in micro-encapsulated form, if appropriate, with one or more of the above-described excipients. 
     Liquid dosage forms for oral administration include pharmaceutically acceptable emulsions, microemulsions, solutions, suspensions, syrups, and elixirs. In addition to the active ingredient, the liquid dosage forms may contain inert diluents commonly used in the art, such as, for example, water or other solvents, solubilizing agents, and emulsifiers such as ethyl alcohol, isopropyl alcohol, ethyl carbonate, ethyl acetate, benzyl alcohol, benzyl benzoate, propylene glycol, 1,3-butylene glycol, oils (in particular, cottonseed, groundnut, corn, germ, olive, castor, and sesame oils), glycerol, tetrahydrofuryl alcohol, polyethylene glycols, and fatty acid esters of sorbitan, and mixtures thereof. 
     Besides inert diluents, the oral compositions can also include adjuvants such as wetting agents, emulsifying and suspending agents, sweetening, flavoring, coloring, perfuming, and preservative agents. 
     Suspensions, in addition to the active inhibitor(s) may contain suspending agents as, for example, ethoxylated isostearyl alcohols, polyoxyethylene sorbitol and sorbitan esters, microcrystalline cellulose, aluminum metahydroxide, bentonite, agar-agar and tragacanth, and mixtures thereof. 
     Formulations for rectal or vaginal administration may be presented as a suppository, which may be prepared by mixing one or more inhibitor(s) with one or more suitable nonirritating excipients or carriers comprising, for example, cocoa butter, polyethylene glycol, a suppository wax or a salicylate, which is solid at room temperature, but liquid at body temperature and, therefore, will melt in the rectum or vaginal cavity and release the active agent. 
     Formulations which are suitable for vaginal administration also include pessaries, tampons, creams, gels, pastes, foams, or spray formulations containing such carriers as are known in the art to be appropriate. 
     Dosage forms for the topical or transdermal administration of an inhibitor(s) include powders, sprays, ointments, pastes, creams, lotions, gels, solutions, patches, and inhalants. The active component may be mixed under sterile conditions with a pharmaceutically acceptable carrier, and with any preservatives, buffers, or propellants which may be required. 
     The ointments, pastes, creams, and gels may contain, in addition to inhibitor(s), excipients, such as animal and vegetable fats, oils, waxes, paraffins, starch, tragacanth, cellulose derivatives, polyethylene glycols, silicones, bentonites, silicic acid, talc, and zinc oxide, or mixtures thereof. 
     Powders and sprays can contain, in addition to an inhibitor(s), excipients such as lactose, talc, silicic acid, aluminum hydroxide, calcium silicates, and polyamide powder, or mixtures of these substances. Sprays can additionally contain customary propellants, such as chlorofluorohydrocarbons and volatile unsubstituted hydrocarbons, such as butane and propane. 
     The inhibitor(s) can be alternatively administered by aerosol. This is accomplished by preparing an aqueous aerosol, liposomal preparation, or solid particles containing the composition. A nonaqueous (e.g., fluorocarbon propellant) suspension could be used. Sonic nebulizers are preferred because they minimize exposing the agent to shear, which can result in degradation of the compound. 
     Ordinarily, an aqueous aerosol is made by formulating an aqueous solution or suspension of the agent together with conventional pharmaceutically acceptable carriers and stabilizers. The carriers and stabilizers vary with the requirements of the particular composition, but typically include nonionic surfactants (Tweens, Pluronics, sorbitan esters, lecithin, Cremophors), pharmaceutically acceptable co-solvents such as polyethylene glycol, innocuous proteins like serum albumin, oleic acid, amino acids such as glycine, buffers, salts, sugars, or sugar alcohols. Aerosols generally are prepared from isotonic solutions. 
     Transdermal patches have the added advantage of providing controlled delivery of an inhibitor(s) to the body. Such dosage forms can be made by dissolving or dispersing the agent in the proper medium. Absorption enhancers can also be used to increase the flux of the inhibitor(s) across the skin. The rate of such flux can be controlled by either providing a rate controlling membrane or dispersing the inhibitor(s) in a polymer matrix or gel. 
     Pharmaceutical compositions of this invention suitable for parenteral administration comprise one or more inhibitors(s) in combination with one or more pharmaceutically acceptable sterile aqueous or nonaqueous solutions, dispersions, suspensions or emulsions, or sterile powders which may be reconstituted into sterile injectable solutions or dispersions just prior to use, which may contain antioxidants, buffers, bacteriostats, solutes which render the formulation isotonic with the blood of the intended recipient or suspending or thickening agents. 
     Examples of suitable aqueous and nonaqueous carriers which may be employed in the pharmaceutical compositions of the invention include water, ethanol, polyols (such as glycerol, propylene glycol, polyethylene glycol, and the like), and suitable mixtures thereof, vegetable oils, such as olive oil, and injectable organic esters, such as ethyl oleate. Proper fluidity can be maintained, for example, by the use of coating materials, such as lecithin, by the maintenance of the required particle size in the case of dispersions, and by the use of surfactants. 
     These compositions may also contain adjuvants such as preservatives, wetting agents, emulsifying agents, and dispersing agents. Prevention of the action of microorganisms may be ensured by the inclusion of various antibacterial and antifungal agents, for example, paraben, chlorobutanol, phenol sorbic acid, and the like. It may also be desirable to include tonicity-adjusting agents, such as sugars, sodium chloride, and the like into the compositions. In addition, prolonged absorption of the injectable pharmaceutical form may be brought about by the inclusion of agents which delay absorption such as aluminum monostearate and gelatin. 
     In some cases, in order to prolong the effect of a drug, it is desirable to slow the absorption of the drug from subcutaneous or intramuscular injection. For example, delayed absorption of a parenterally administered drug form is accomplished by dissolving or suspending the drug in an oil vehicle. 
     Injectable depot forms are made by forming microcapsule matrices of inhibitor(s) in biodegradable polymers such as polylactide-polyglycolide. Depending on the ratio of drug to polymer, and the nature of the particular polymer employed, the rate of drug release can be controlled. Examples of other biodegradable polymers include poly(orthoesters) and poly(anhydrides). Depot injectable formulations are also prepared by entrapping the drug in liposomes or microemulsions which are compatible with body tissue. 
     The preparations of agents may be given orally, parenterally, topically, or rectally. They are, of course, given by forms suitable for each administration route. For example, they are administered in tablets or capsule form, by injection, inhalation, eye lotion, ointment, suppository, infusion; topically by lotion or ointment; and rectally by suppositories. Oral administration is preferred. 
     The phrases “parenteral administration” and “administered parenterally” as used herein means modes of administration other than enteral and topical administration, usually by injection, and includes, without limitation, intravenous, intramuscular, intraarterial, intrathecal, intracapsular, intraorbital, intracardiac, intradermal, intraperitoneal, transtracheal, subcutaneous, subcuticular, intraarticular, subcapsular, subarachnoid, intraspinal and intrasternal injection, and infusion. 
     The phrases “systemic administration,” “administered systemically,” “peripheral administration” and “administered peripherally” as used herein mean the administration of a ligand, drug, or other material other than directly into the central nervous system, such that it enters the patient&#39;s system and thus, is subject to metabolism and other like processes, for example, subcutaneous administration. 
     These inhibitors(s) may be administered to humans and other animals for therapy by any suitable route of administration, including orally, nasally, as by, for example, a spray, rectally, intravaginally, parenterally, intracisternally, and topically, as by powders, ointments or drops, including buccally and sublingually. 
     Regardless of the route of administration selected, the inhibitor(s), which may be used in a suitable hydrated form, and/or the pharmaceutical compositions of the present invention, are formulated into pharmaceutically acceptable dosage forms by conventional methods known to those of skill in the art. 
     Actual dosage levels of the active ingredients in the pharmaceutical compositions of this invention may be varied so as to obtain an amount of the active ingredient which is effective to achieve the desired therapeutic response for a particular patient, composition, and mode of administration, without being toxic to the patient. 
     The concentration of a disclosed compound in a pharmaceutically acceptable mixture will vary depending on several factors, including the dosage of the compound to be administered, the pharmacokinetic characteristics of the compound(s) employed, and the route of administration. In general, the compositions of this invention may be provided in an aqueous solution containing about 0.1-10% w/v of a compound disclosed herein, among other substances, for parenteral administration. Typical dose ranges are from about 0.01 to about 50 mg/kg of body weight per day, given in 1-4 divided doses. Each divided dose may contain the same or different compounds of the invention. The dosage will be an effective amount depending on several factors including the overall health of a patient, and the formulation and route of administration of the selected compound(s). 
     Combination Therapy 
     One aspect of the invention relates to the treatment of metastatic cancer, wherein a peptide epoxyketone or a pharmaceutically acceptable salt thereof is administered with one or more other therapeutic agents. Such combination treatment may be achieved by way of the simultaneous, sequential, or separate dosing of the individual components of the treatment. 
     In certain embodiments, the one or more other therapeutic agent is selected from an HDAC inhibitor, an antibiotic, a taxane, an antiproliferative/antimitotic alkylating agents, a platinum coordination complex, a steroid, an immunomodulator, a topoisomerase inhibitor, an m-TOR inhibitor, protein kinase inhibitor, another proteasome inhibitor or radiotherapy. 
     In certain embodiments, the other therapeutic agent is an HDAC inhibitor (e.g., Trichostatin A, depsipeptide, apicidin, A-161906, scriptaid, PXD-101, CHAP, butyric acid, depudecin, oxamflatin, phenylbutyrate, valproic acid, SAHA (Vorinostat), MS275 (N-(2-Aminophenyl)-4-[N-(pyridine-3-ylmethoxy-carbonyl)aminomethyl]benzamide), LAQ824/LBH589, CI994, and MGCD0103). In certain such embodiments, the other agent is SAHA (suberoylanilide hydroxamic acid). 
     In certain embodiments, the other therapeutic agent is an antibiotic (e.g., dactinomycin (actinomycin D), daunorubicin, doxorubicin and idarubicin). In certain such embodiments, the other therapeutic agent comprises doxorubicin. In certain such embodiments, the other therapeutic agent is Doxil. 
     In certain embodiments, the other therapeutic agent is a taxane (e.g., paclitaxel and docetaxel). 
     In certain embodiments, the other therapeutic agent is an antiproliferative/antimitotic alkylating agents such as a nitrogen mustard (e.g., mechlorethamine, ifosphamide, cyclophosphamide and analogs, melphalan, and chlorambucil). In certain such embodiments, the other therapeutic agent is cyclophosphamide or melphalan. 
     In certain embodiments, the other therapeutic agent is a platinum coordination complex (e.g., cisplatin and carboplatin). In certain such embodiments, the other therapeutic agent is carboplatin. 
     In certain embodiments, the other therapeutic agent is a steroid (e.g., hydrocortisone, dexamethasone, methylprednisolone and prednisolone). In certain such embodiments, the other therapeutic agent is dexamethasone. 
     In certain embodiments, the other therapeutic agent is an immunomodulator (e.g., thalidomide, CC-4047 (Actimid), and lenalidomide (Revlimid). In certain such embodiments, the other therapeutic agent is lenalidomide. 
     In certain embodiments, the other therapeutic agent is a topoisomerase inhibitor (e.g., irinotecan, topotecan, camptothecin, lamellarin D, and etoposide). 
     In certain embodiments, the other therapeutic agent is an m-TOR inhibitor (e.g., CCI-779, AP23573 and RAD-001). 
     In certain embodiments, the other therapeutic agent is a protein kinase inhibitor (e.g., sorafenib, imatinib, dasatinib, sunitinib, pazopanib, and nilotinib). In certain such embodiments, the protein kinase inhibitor is sorafenib. 
     Administration of the peptide epoxyketone may precede or follow the other therapeutic agent by intervals ranging from minutes to days. In certain such embodiments, the peptide epoxyketone and the other therapeutic agent may be administered within about 1 minute, about 5 minutes, about 10 minutes, about 30 minutes, about 60 minutes, about 2 hours, about 4 hours, about 6 hours, 8 hours, about 10 hours, about 12 hours, about 18 hours, about 24 hours, about 36 hours, or even about 48 hours or more of one another. Preferably, administration of the peptide epoxyketone and the other therapeutic agent will be within about 1 minute, about 5 minutes, about 30 minutes, or even about 60 minutes of one another. 
     In certain embodiments, the peptide epoxyketone and the other therapeutic agent may be administered according to different dosing schedules (e.g., the peptide epoxyketone, for example may be administered once a day while the other therapeutic agent may be administered only once every three weeks) such that in some instances administration of the peptide epoxyketone and the other therapeutic agent will be within about 60 minutes of one another, while in other instances, administration of the peptide epoxyketone and the other therapeutic agent will be within days or even weeks of one another. 
     As used herein, the term “regimen” is a predetermined schedule of one or more therapeutic agents for the treatment of a cancer. Accordingly, when a therapeutic agent is administered “alone,” the regimen does not include the use of another therapeutic agent for the treatment of cancer. 
     In certain embodiments, combinations as described herein may be synergistic in nature, meaning that the therapeutic effect of the combination of the peptide epoxyketone and the other therapeutic agent(s) is greater than the sum of the individual effects. 
     In certain embodiments, combinations as described herein may be additive in nature, meaning that the therapeutic effect of the combination of the peptide epoxyketone and the other therapeutic agent(s) is greater than the effect of each agent individually (i.e., the therapeutic effect is the sum of the individual effects). 
     EXEMPLIFICATION 
     Example 1 
     6-8 week old female BALB/c mice were challenged in the mammary fat pad with 4T1 mammary carcinoma cells (1×10 5 /mouse). Treatment was initiated on Day 3 post tumor challenge. Compound 1 was administered orally at 30 or 40 mg/kg on a weekly schedule of QDX2 or QDX5. 
     Compound 1 treatment reduced the number of metastatic tumors in the lung by about 50%. Both dose schedules and dose levels of Compound 1 tested were effective in repressing metastasis ( FIG. 1 ). 
     EQUIVALENTS 
     Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, numerous equivalents to the compounds and methods of use thereof described herein. Such equivalents are considered to be within the scope of this invention and are covered by the following claims. 
     All of the above-cited references and publications are hereby incorporated by reference.