Cyclic polypeptide compound and use thereof

A compound X-6 or a pharmaceutically acceptable salt thereof,

• wherein W is —NH—CO— or —NH—CO—NH—,
• R8 is linear C1-10 alkyl;
• R9 is H or C1-C4 alkyl substituted by 1 or 2 R9-1;
• R9-1 is carboxyl or amido;
• L1 and L2 are each independently a chemical bond, C1-C4 alkylene, or —S—(CH2)k—;
• k is 0, 1, 2, 3, or 4;
• —X3— is —X3-1—Y2—;
• —X3-1— is a chemical bond, non-natural amino acid residue, or natural amino acid residue;
• Y2 is
• R6 is C1-C4 alkyl, C1-C4 alkyl substituted by 1 or 2 R6-1, or C3-C6 cycloalkyl;
• each R6-1 is independently halogen, C3-C6 cycloalkyl, C6-C10 aryl, or C6-C10 aryl substituted by one or more R6-1-1;
• R6-1-1 is each independently halogen;
• Cy is a chemical bond, 3- to 6-membered heterocycloalkylene, 5- to 6-membered heteroarylene, or C6-C10 arylene;
• the heteroatom of the 3- to 6-membered heterocycloalkylene is selected from one or more of N, O, and S, the number of heteroatoms is 1, 2, or 3, and at least one N is included:
• in the 5- to 6-membered heteroarylene, the heteroatom is selected from one or more of N, O, and S, the number of heteroatoms is 1, 2, or 3, and at least one N is included:
• -L3- is -L31-L3-2-L3-3-;
• -L3-1 is a chemical bond,
• wherein T1 and T2 are each independently 0, 1, 2, 3, or 4, and T3 and T4 are each independently 0, 1, 2, 3, or 4:
• -L3-2- is —X5—Y3—;
• —X5— is a chemical bond, a natural amino acid residue, or a polypeptide formed by 2-6 natural amino acids;
• —Y3— is a chemical bond,
• T5 and T6 are each independently 0, 1, 2, 3, or 4:
• E and Q are each independently C1-6 alkylene or -(OCH2CH2)j′—, and j′ is 1, 2, 3, 4, 5, or 6:
• A is a chemical bond or —NH—;
• -L3-3- is a chemical bond, —NH—, -carbonyl-6- to 12-membered heteroarylene-, -carbonyl-C1-6 alkylene-3- to 6-membered heterocycloalkylene-, —NH—C1-6 alkylene-3- to 6-membered heterocycloalkylene-, or 3- to 6-membered heterocycloalkylene;
• the heteroatom of the 3- to 6-membered heterocycloalkylene is selected from one or more of N, O, and S, the number of heteroatoms is 1, 2, or 3, and at least one N is included;
• the heteroatom of the 6- to 12-membered heteroarylene is selected from one or more of N, O, and S, the number of heteroatoms is 1, 2, or 3, and at least one N is included;
• R10 is hydroxyl or amino;
• R11 is a chelating group;
• the chelating group
• NOTA, HBED-CC, NODAGA, NOTAGA, DOTAGA, TRAP, NOPO, PCTA, DFO, DTPA, CHX-DTPA, AAZTA, or DEDPA.