Peg linker and ligand drug conjugate
A PEG linker as represented by formula (I), wherein n and m are respectively an integer from 1 to 7, providing the PEG linker with 1 to 49 linking sites. A ligand drug conjugate as represented by formula (II). The conjugate uses the PEG linker to increase a drug loading capacity and drug loading diversity, thereby improving pharmaceutical efficacy. Y1-PEG1-{R 1 -PEG2-{Y4} n } m (I) TM-{R 2 -PEG1-{R 1 -PEG2-{R 3 -A′-drug} n } m } l (II)
1. A ligand drug conjugate or a pharmaceutically acceptable salt thereof
wherein,
the ligand drug conjugate is selected from the group consisting of APEGA-2, APEGA-4, APEGA-5 and APEGA-6, each having the structural formula shown below:
wherein, Val is proline; Iri is irinotecan; h is the same or not the same, and each independently is an integer selected from 1 to 240; TM is a ligand unit, the TM ligand unit is selected from the group consisting of a monoclonal antibody and a polyclonal antibody.