Chlorotoxin conjugates and methods of use thereof

A compound having the structure of Formula (III), or a pharmaceutically acceptable salt thereof:

• wherein:
• R1, R2, R3, R4, R5, R6, R7, R8, R15, and R16 are each independently selected from hydrogen, C1-C6 alkyl, C1-C6 alkylene-COOH, sulfonate, —COOH, —SO2—NH2, or C1-C6 alkoxy;
• R9 is hydrogen, sulfonate, or —COOH;
• L1 is C3-C6 alkylene;
• L2 is C1-C10 alkylene;
• L3 is a bond, —O—, —NR10—, —NR10—C1-C6 alkylene-, —O—NR10—, —NR10—C1-C6 alkylene-(O—C1-C6 alkylene)n-, —NR10-L4-, —NR10—C1-C6 alkylene-NR11—(C(═O)—C1-C6 alkylene-O—)m—, or —NR10—C1-C6 alkylene-NR10—C1-C6 alkylene-NR10—C1-C6 alkylene-;
• L4 is a bond, -heterocyclyl-, or -heterocyclyl-C1-C6 alkylene-;
• R10 is hydrogen or C1-C6 alkyl;
• R11 is hydrogen or C1-C6 alkyl;
• R12 and R13 are independently selected from hydrogen, C1-C6 alkyl, or R12 and R13 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring;
• R14 is hydrogen or C1-C6 alkylene, -(L5)-aryl, -(L5)-heteroaryl, —NR17R18, R14 and R19 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring, or R14 and R20 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring;
• L5 is a bond, C1-C10 alkylene, —O—, —NR10—;
• R17 and R18 are each independently hydrogen or aryl;
• R19 and R20 are independently selected from hydrogen, C1-C6 alkyl, R14 and R19 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring, or R14 and R20 are joined together along with the other atoms to which they are attached to form a 5-membered or 6-membered carbocyclic or heterocyclic ring;
• n is 0, 1, 2, or 3;
• m is 0, 1, 2, or 3;
• p is 0, 1, 2, or 3;
• q is 0, 1, 2, or 3;
• and
• A4 is a polypeptide having at least 90% sequence identity with MCMPCFTTDHQMARRCDDCCGGRGRGKCYGPQCLCR (SEQ ID NO:
• 9) or a fragment thereof.