Methods for treating spinal cord injury

1. A method for treating a spinal cord injury in a subject by promoting axon regeneration in a Central Nervous System (CNS) neuron, the method comprising:

exposing the CNS neuron of the subject to an effective amount of a necrostatin and an effective amount of an apoptosis inhibitor thereby to promote the regeneration of the axon of the CNS neuron;

wherein the necrostatin is selected from the group consisting of:

(i) a Nec-1 related compound of Formula I:

or a pharmaceutically acceptable salt, ester, or prodrug thereof, wherein

X is O or S;

R 1 is hydrogen, C 1 -C 6 alkyl, C 1 -C 6 alkoxyl, or halogen; and

R 2 is hydrogen or C 1 -C 6 alkyl;

(ii) a Nec-1 related compound of Formula I-A:

or a pharmaceutically acceptable salt, ester, or prodrug thereof,

wherein R 1 is H, alkyl, alkoxyl, or a halogen and R 2 is H or an alkyl;

(iii) a Nec-1 related compound of Formula I-B:

or a pharmaceutically acceptable salt, ester, or prodrug thereof;

(iv) a Nec-1 related compound of Formula I-C

or a pharmaceutically acceptable salt, ester, or prodrug thereof;

(v) a Nec-1 related compound of Formula I-D

or a pharmaceutically acceptable salt thereof;

(vi) a Nec-1 related compound of Formula I-E:

or a pharmaceutically acceptable salt, ester, or prodrug thereof,

wherein R 1 is H, alkyl, alkoxyl, or a halogen and R 2 is H or an alkyl;

(vii) a Nec-2 related compound of Formula II:

or a pharmaceutically acceptable salt, ester, or prodrug thereof, wherein:

X is —CH 2 —, —C(H)(R 14 )—, —C(═S)—, —C(═NH)—, or —C(O)—;

R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7 , R 8 , R 9 , and R 10 each represent independently hydrogen, acyl, acetyl, alkyl, halogen, amino, C 1 -C 6 alkoxyl, nitro, —C(O)R 12 , —C(S)R 12 , —C(O)OR 12 , —C(O)NR 12 R 13 , —C(S)NR 12 R 13 , or —S(O 2 )R 12 ;

R 11 is hydrogen, acyl, acetyl, alkyl, or acylamino;

R 12 and R 13 each represent independently hydrogen, an optionally substituted alkyl, an optionally substituted aryl, an optionally substituted heteroaryl, an optionally substituted aralkyl, or an optionally substituted heteroaralkyl;

R 14 is acyl, acetyl, alkyl, halogen, amino, acylamino, nitro, —SR 11 , —N(R 11 ) 2 , or —OR 11 ;

the bond indicated by (a) can be a single or double bond; and

the bond indicated by (b) can be a single or double bond;

(viii) a Nec-2 related compound of Formula II-A:

or a pharmaceutically acceptable salt thereof, wherein:

R 1 , R 2 , R 5 , R 6 , R 7 , and R 10 each represent independently hydrogen, alkyl, halogen, amino, or methoxyl; and

R 3 , R 4 , R 8 , and R 9 are C 1 -C 6 alkoxyl;

(ix) a Nec-3 related compound of Formula III:

or a pharmaceutically acceptable salt, ester, or prodrug thereof, wherein:

Z is —CH 2 —, —CH 2 CH 2 —, —O—, —S—, —S(O)—, —S(O 2 )—, or —N(R 7 )—;

R 1 , R 3 , and R 5 each represent independently for each occurrence hydrogen, halogen, hydroxyl, amino, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, C 1 -C 6 alkoxy-C 1 -C 6 alkyl, C 1 -C 6 alkanoyl, C 1 -C 6 alkylsulfinyl, C 1 -C 6 alkylsulfinyl-C 1 -C 6 alkyl, C 1 -C 6 alkylsulfonyl, C 1 -C 6 alkylsulfonyl-C 1 -C 6 alkyl, aryl, aralkyl, heterocycloalkyl, heteroaryl, or heteroaralkyl;

R 2 and R 4 are C 1 -C 6 alkoxy;

R 6 is —C(O)R 8 , —C(S)R 8 , —C(O)OR 8 , —C(O)NR 8 R 9 , —C(S)NR 8 R 9 , —C(NH)R 8 , or —S(O 2 )R 8 ;

R 7 is alkyl, aralkyl, or heteroaralkyl;

R 8 and R 9 each represent independently hydrogen, C 1 -C 6 alkyl, heteroalkyl, aryl, heteroaryl, aralkyl, or heteroaralkyl; and

n represents independently for each occurrence 0, 1, or 2;

(x) a Nec-4 related compound of Formula IV:

or a pharmaceutically acceptable salt, ester, or prodrug thereof, wherein:

R 1 is

R 2 and R 3 each represent independently for each occurrence hydrogen or methyl;

R 4 represents independently for each occurrence halogen, hydrogen, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, or C 2 -C 4 alkynyl;

R 5 is C 1 -C 4 alkyl;

R 6 is hydrogen, halogen, or —CN;

R 7 is hydrogen or C 1 -C 4 alkyl;

R 8 is C 1 -C 6 alkyl, or R 8 taken together with R 9 , when present, forms a carbocyclic ring;

R 9 is hydrogen or C 1 -C 6 alkyl, or R 9 taken together with R 8 forms a carbocyclic ring;

R 10 is hydrogen or C 1 -C 6 alkyl;

A is phenylene or a 5-6 membered heteroarylene;

X is N or —C(R 9 )—;

Y is N or —C(R 10 )—;

Z is S or O; and

m and n each represent independently 1, 2, or 3;

(xi) a Nec-5 related compound of Formula V:

or a pharmaceutically acceptable salt, ester, or prodrug thereof, wherein:

A is a saturated or unsaturated 5-6 membered carbocyclic ring;

X is a bond or C 1 -C 4 alkylene;

R 1 is C 1 -C 6 alkyl, halogen, hydroxyl, C 1 -C 6 alkoxyl, —N(R 4 ) 2 , —C(O)R 4 , CO 2 R 4 , or C(O)N(R 4 ) 2 ;

R 2 is

R 3 is —C 1 -C 6 alkylene-CN, —CN, C 1 -C 6 alkyl, or C 2 -C 6 alkenyl;

R 4 represents independently for each occurrence hydrogen, C 1 -C 6 alkyl, aryl, or aralkyl;

R 5 represents independently for each occurrence C 1 -C 6 alkyl, halogen, hydroxyl, C 1 -C 6 alkoxyl, —N(R 4 ) 2 , —C(O)R 4 , CO 2 R 4 , or C(O)N(R 4 ) 2 ;

B is a 5-6 membered heterocyclic or carbocylic ring; and

n and p each represent independently 0, 1, or 2;

(xii) a Nec-5 related compound of Formula V-A:

or a pharmaceutically acceptable salt, ester, or prodrug thereof, wherein:

R 1 is C 1 -C 6 alkyl, halogen, hydroxyl, C 1 -C 6 alkoxyl, or —N(R 4 ) 2 ;

R 2 is

R 3 is —C 1 -C 6 alkylene-CN;

R 4 represents independently for each occurrence hydrogen, C 1 -C 6 alkyl, aryl, or aralkyl;

R 5 represents independently for each occurrence C 1 -C 6 alkyl, halogen, hydroxyl, C 1 -C 6 alkoxyl, —N(R 4 ) 2 , —C(O)R 4 , CO 2 R 4 , or C(O)N(R 4 ) 2 ;

B is a 5-6 membered heterocyclic or carbocylic ring; and

n and p each represent independently 0, 1, or 2;

(xiii) a Nec-7 related compound of Formula VII:

or a pharmaceutically acceptable salt, ester, or prodrug thereof, wherein:

R 1 , R 2 , and R 3 each represent independently hydrogen or C 1 -C 4 alkyl;

R 4 is

R 5 and R 6 each represent independently for each occurrence halogen, C 1 -C 6 alkyl, hydroxyl, C 1 -C 6 alkoxyl, —N(R 7 ) 2 , —NO 2 , —S—C 1 -C 6 alkyl, —S-aryl, —SO 2 —C 1 -C 6 alkyl, —SO 2 -aryl, —C(O)R 7 , —CO 2 R 7 , —C(O)N(R 7 ) 2 , heterocycloalkyl, aryl, or heteroaryl;

R 7 represents independently for each occurrence hydrogen, C 1 -C 6 alkyl, aryl, or aralkyl; or two occurrences of R 7 attached to the same nitrogen atom are taken together with the nitrogen atom to which they are attached to form a 3-7 membered heterocyclic ring;

A is a 5-6 membered heterocyclic ring; and

p is 0, 1, or 2;

(xiv) a Nec-7 related compound of Formula VIII:

or a pharmaceutically acceptable salt, ester, or prodrug thereof, wherein:

each X 1 , X 2 , X 3 , X 4 , X 5 , and X 6 is selected, independently, from N or CR X1 ;

each Y 1 , Y 2 , and Y 3 is selected, independently, from O, S, NR Y1 , or CR Y2 R Y3 ;

each Z 1 and Z 2 is selected, independently, from O, S, or NR Z1 ;

each R Y1 and R Z1 is selected, independently, from H, optionally substituted C 1-6 alkyl, optionally substituted C 2-6 alkenyl, optionally substituted C 2-6 alkynyl, optionally substituted cycloalkyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, —C(═O)R 5A , —C(═O)OR 5A , or —C(═O)NR 5A R 6A ;

each R X1 , R Y2 , and R Y3 is selected, independently, from H, halogen, CN, NC, NO 2 , N 3 , OR 3 , SR 3 , NR 3 R 4 , —C(═O)R 5A , —C(═O)OR 5A , —C(═O)NR 5A R 6A , —S(═O)R 5A , —S(═O) 2 R 5A , —S(═O) 2 OR 5A , —S(═O) 2 NR 5A R 6A , optionally substituted C 1-6 alkyl, optionally substituted C 2-6 alkenyl, optionally substituted C 2-6 alkynyl, optionally substituted cycloalkyl, optionally substituted heterocyclyl, optionally substituted aryl, or optionally substituted heteroaryl;

each R 1 , R 2 R 5A , R 5B , R 6A , and R 6B is selected from H, optionally substituted C 1-6 alkyl, optionally substituted C 2-6 alkenyl, optionally substituted C 2-6 alkynyl, optionally substituted cycloalkyl, optionally substituted heterocyclyl, optionally substituted aryl, or optionally substituted heteroaryl; or R 5A and R 6A , or R 5B and R 6B combine to form a heterocyclyl; and

each R 3 and R 4 is selected from H, optionally substituted C 1-6 alkyl, optionally substituted cycloalkyl, optionally substituted heterocyclyl, optionally substituted aryl, optionally substituted heteroaryl, —C(═O)R 5B , —C(═S)R 5B , —C(═NR 6B )R 5B , —C(═O)OR 5B , —C(═O)NR 5B R 6B , —S(═O)R 5B , —S(═O) 2 R 5B , —S(═O) 2 OR 5B , or —S(═O) 2 NR 5B R 6B ; and

(xv) a Nec-4 related compound of Formula IX:

or a pharmaceutically acceptable salt, ester, or prodrug thereof, wherein:

X 1 and X 2 are, independently, N or CR 4 ;

X 3 is selected from O, S, NR 5 , or —(CR 5 ) 2 ;

Y is selected from C(O) or CH 2 ; and

Z is (CR 6 R 7 ) n ;

R 1 is selected from H, halogen, optionally substituted C 1-6 alkyl, or optionally substituted C 1-6 cycloalkyl, or optionally substituted aryl;

R 2 is selected from H or optionally substituted C 1-6 alkyl;

R 3 is optionally substituted aryl;

each R 4 is selected from H, halogen, carboxamido, nitro, cyano, optionally substituted C 1-6 alkyl, or optionally substituted aryl;

R 5 is selected from H, halogen, optionally substituted C 1-6 alkyl, or optionally substituted aryl;

each R 6 and R 7 is, independently, selected from H, optionally substituted C 1-6 alkyl, or aryl; and

n is 0, 1, 2, or 3; and

wherein the apoptosis inhibitor is a pan-caspase inhibitor, a caspase-1 inhibitor, a caspase-2 inhibitor, a caspase-3 inhibitor, a caspase-4 inhibitor, a caspase-5 inhibitor, a caspase-6 inhibitor, a caspase-7 inhibitor, a caspase-8 inhibitor, a caspase-9 inhibitor, or a combination thereof.

2. The method of claim 1 , wherein the neuron is ex vivo.

3. The method of claim 1 , wherein the neuron is in vivo.

4. The method of claim 1 , wherein the CNS neuron is selected from the group consisting of a sensory neuron, a motor neuron, a cortical neuron, a pyramidal neuron, a cerebellar neuron, a hippocampal neuron, and a midbrain neuron.

5. The method of claim 1 , wherein the necrostatin is necrostatin-1, necrostatin-2, necrostatin-3, necrostatin-4, necreostatin-5, and necrostatin-7, or a combination thereof.

6. The method of claim 1 , wherein from about 0.05 mg to about 2 mg of the necrostatin is administered.

7. The method of claim 1 , wherein the apoptosis inhibitor is a pan-caspase inhibitor.

8. The method of claim 7 , wherein the pan-caspase inhibitor is zVAD, IDN-6556 or a combination thereof.

9. The method of claim 1 , wherein the necrostatin, the apoptosis inhibitor, or both the necrostatin and the apoptosis inhibitor are administered locally.

10. The method of claim 1 , wherein the necrostatin, the apoptosis inhibitor, or both the necrostatin and the apoptosis inhibitor are administered systemically.

11. The method of claim 1 , wherein the necrostatin, the apoptosis inhibitor, or both the necrostatin and the apoptosis inhibitor are administered sequentially or simultaneously.

12. The method of claim 1 , wherein the spinal cord injury is selected from the group consisting of chronic spinal cord injury, acute spinal cord injury, and traumatic spinal cord injury.