Ligand-drug conjugate containing hydrophilic group and pharmaceutical use thereof

Abstract

The present disclosure relates to a ligand-drug conjugate containing a hydrophilic group and the pharmaceutical use thereof. Specifically, provided is a ligand-drug conjugate as shown in formula IIA, wherein the functional groups are as defined in the text. Further provided are a method for preparing the ligand-drug conjugate as shown in IIA, a pharmaceutical composition containing the ligand-drug conjugate, and the use thereof as a therapeutic agent.

Description

Ligand-drug conjugate comprising hydrophilic group and its use in medicine TECHNICAL FIELD

[0001] The present disclosure belongs to the field of medicine, in particular to a ligand-drug conjugate comprising hydrophilic group and its use in medicine. BACKGROUND

[0002] Ligand-drug-conjugate (LDC) is a new type of drug that combines the high specificity of targeting agent and the high activity of small molecule drug (cytotoxic agent, immunomodulator or other agent), such as common antibody-drug conjugate (ADC), aiming to improve the targeting of small molecule drugs while reducing their toxic side effects.

[0003] The following main factors need to be considered in the design process of ligand-drug-conjugate: targeting of ligand, toxicity of toxin molecule, linker. The linker is responsible for linking the antibody and cytotoxic small molecule of ADC together, which is crucial for the safety and stability of ADC drug. The ideal linker needs to be stable enough in blood circulation, can effectively avoid the release of toxin small molecule in blood circulation and normal tissues and make it stable and inactive, while at the same time needs to be able to efficiently release toxin small molecule in tumor tissue and cells. For example, camptothecin drugs are a class of highly hydrophobic chemical small molecules, and the stability and half-life of ligand-drug-conjugate prepared have no obvious advantage over similar products.

[0004] Improving the hydrophilicity of the linker is beneficial for the coupling reaction of toxin molecules with antibodies in aqueous phase, while avoiding the decrease of ADC yield caused by the aggregation of proteins. More importantly, the hydrophilicity of the linker is beneficial for the delivery of toxin small molecules in ADC drugs to the inside of tumor cells, improving the premature release of ADC drugs during transport and significantly affecting the safety and effectiveness of ADC drugs.

[0005] The introduction of polar groups such as sulfonic acid or polyethylene glycol in the linker can not only enhance the water solubility of linker-drug, reduce the probability of aggregation during the preparation of ADC molecules, but also enhance the ability of toxin small molecules to overcome the P-glycoprotein (PgP) efflux effect (Cancer Res, 2010, 70(6): 2528-2537 and MAbs, 2018, 10(7): 960-967). Other solutions to improve the linker include WO2019081455, WO2022253284, WO2022228493A, WO2023280227 and WO2024006272A. However, there is still a need to develop new ligand-drug-conjugate with improved pharmacokinetics and pharmacodynamics. SUMMARY

[0006] The present disclosure provides a compound of Formula IA or a pharmaceutically acceptable salt thereof,

[0007] wherein D is a drug unit; Sp is -Lp-(X) b ; X is a spacer unit; Lp is an amino acid unit; b is selected from 0, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10; U is a hydrophilic unit comprising polyethylene glycol structural units and polysarcosine structural units; L is a stretch unit; R is a linking group; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0008] In some embodiments, the compound of Formula IA or a pharmaceutically acceptable salt thereof is where b = 1.

[0009] In some embodiments, the compound of Formula IA or a pharmaceutically acceptable salt thereof is a compound of Formula la or a pharmaceutically acceptable salt thereof,

[0010] wherein D is a drug unit; X is a spacer unit; Lp is an amino acid unit; U is a hydrophilic unit comprising polyethylene glycol structural units and polysarcosine structural units; L is a stretch unit; R is a linking group; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0011] In some embodiments, the compound of Formula IA or a pharmaceutically acceptable salt thereof is where b = 0.

[0012] In some embodiments, the compound of Formula IA or a pharmaceutically acceptable salt thereof is a compound of Formula lb or a pharmaceutically acceptable salt thereof, wherein D is a drug unit; Lp is an amino acid unit; U is a hydrophilic unit comprising polyethylene glycol structural units and polysarcosine structural units; L is a stretch unit; R is a linking group; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0013] In some embodiments, the compound of Formula IA or la or a pharmaceutically acceptable salt thereof is where the spacer unit comprises / or is selected from wherein R e is selected from halogen, C 1-6 alkyl, C 1-6 alkoxy or v is selected from an integer from 0-4; B1 is a bond to the Lp terminus; B2 is a bond to the -D terminus; R 18 is selected from hydrogen, C 1-6 alkyl or halogenated C 1- 6alkyl, for example hydrogen or methyl.

[0014] In some embodiments, the spacer unit of the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, comprises / consists of wherein R e is selected from halogen, C 1-6 alkyl, C 1-6 alkoxy or v is an integer selected from 0-4; B1is the bond to the Lp terminus; B2is the bond to the -D terminus.

[0015] In some embodiments, the spacer unit of the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, comprises / consists of wherein R e is selected from halogen, C 1-6 alkyl, C 1-6 alkoxy or v is an integer selected from 0-4; B1is the bond to the Lp terminus; B2is the bond to the -D terminus; R 18 is selected from hydrogen, C 1-6 alkyl or halogenated C 1- 6alkyl, for example hydrogen or methyl.

[0016] In some embodiments, the spacer unit of the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, comprises / consists of wherein R e is selected from halogen, C 1-6 alkyl, C 1-6 alkoxy or v is an integer selected from 0-4; B1is the bond to the Lp terminus; B2is the bond to the -D terminus.

[0017] In some embodiments, the spacer unit of the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, comprises / consists of wherein R e is selected from halogen, C 1-6 alkyl, C 1-6 alkoxy or v is an integer selected from 0-4; B1is the bond to the Lp terminus; B2is the bond to the -D terminus; R 18 is selected from hydrogen, C 1-6 alkyl or halogenated C 1-6 alkyl, for example hydrogen or methyl.

[0018] In some embodiments, the spacer unit of the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, comprises / consists of p-aminobenzyloxycarbonyl.

[0019] In some embodiments, the spacer unit of the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, comprises / consists of wherein B1is the bond to the Lp terminus; B2is the bond to the -D terminus.

[0020] In other embodiments, the spacer unit in a compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, comprises / consists of wherein B1is a bond to the Lp terminus; and B2is a bond to the -D terminus.

[0021] In some embodiments, the spacer unit in a compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, comprises / consists of the following moieties: -(CR 1 R 2 ) m1 -O(CR 1 R 2 ) m2 -CR 3 R 4 -C(O)-, -(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -CR 3 R 4 -C(O)-, -(CR 1 R 2 ) m1 O-CR 3 R 4 (CR 1 R 2 ) m2 -, -(CR 1 R 2 ) m1 OCR 3 R 4 -C(O)-, -(CR 1 R 2 ) m1 -O-(CR 1 R 2 ) m2 C(O)- or -(CR 1 R 2 ) m1 -S-(CR 1 R 2 ) m2 -CR 3 R 4 -C(O)-, -(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -O-CR 3 R 4 -C(O)-, -(CR1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -OMC(O)- and -(CR) 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -CR 3 R 4 -,

[0022] Where R 1 and R 2 They may be the same or different, and each is independently selected from hydrogen, deuterium, halogen or alkyl;

[0023] R 3 Selected from hydrogen, C 3-6 cycloalkylalkyl, C 3-6 Cycloalkyl or 3-6 membered heterocyclic alkyl; R 4 Selected from hydrogen, haloalkyl, C 3-6 Cycloalkyl or 3-6 membered heterocycloalkyl; or, R 3 and R 4 Together with the carbon atoms it is attached to, they form C 3-6 Cycloalkyl or 3-6 membered heterocyclic alkanes;

[0024] m1 and m2 are each independently selected from 0, 1, 2 or 3;

[0025] M is selected from C 3-6 Cycloalkyl or 3-6 membered heterocyclic alkyl.

[0026] In some embodiments, the spacer unit in the compound of formula IA or Ia or its pharmaceutically acceptable salt comprises / or is selected from -(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -OMC(O)-, where R 1 R 2 m1 and m2 are defined as described above.

[0027] In some embodiments, the spacer unit X in the compound of formula IA or Ia or its pharmaceutically acceptable salt comprises / or is selected from...

[0028] In some embodiments, the spacer unit X in the compound of formula IA or Ia or its pharmaceutically acceptable salt comprises / or is selected from...

[0029] In some embodiments, the spacer unit X in the compounds of formula IA or la, or pharmaceutically acceptable salts thereof, comprises / consists of -(CR 1 R 2 ) m1 -O(CR 1 R 2 ) m2 -CR 3 R 4 -C(O)- and -(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -CR 3 R 4 -C(O)-, wherein R 1 , R 2 , R 3 , R 4 , m1, m2 are as defined above.

[0030] In some embodiments, the spacer unit X in the compounds of formula IA or la, or pharmaceutically acceptable salts thereof, comprises / consists of -(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -O-CR 3 R 4 -C(O)-, wherein R 1 , R 2 , R 3 , R 4 , m1, m2 are as defined above.

[0031] In some embodiments, R 3 is selected from C 3-6 cycloalkyl, e.g. cyclopentyl, cyclopropyl, R 4 is selected from H. In some embodiments, R 4 is selected from C 3-6 cycloalkyl, R 3 is selected from H.

[0032] In some embodiments, R 3 is selected from 3-6 membered heterocycloalkyl, R 4 is selected from H.

[0033] In some embodiments, R 3 and R 4 together with the carbon atom to which they are attached form a C 3-6 cycloalkyl, e.g. cyclopropyl, cyclobutyl, cyclopentyl.

[0034] In some embodiments, the spacer unit X in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, comprises or is selected from the group consisting of -(CH2)3-C(O)-, -CH2-O-CH2-C(O)-, -(CH2)2-O-CH2-C(O)-,

[0035] In some embodiments, the spacer unit X in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from the group consisting of -NHCH2-, -NH-(CH2)3-C(O)-, -NH-CH2-O-CH2-C(O)-, -NH-(CH2)2-O-CH2-C(O)-,

[0036] In some embodiments, the spacer unit in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from -(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -CR 3 R 4 -.

[0037] In some embodiments, the spacer unit in the compound of Formula IA, or a pharmaceutically acceptable salt thereof, is selected from -NHCH2-.

[0038] In another aspect, the hydrophilic unit in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is -R b -[Re-(OCH2CH2) q -R c -R f -[C(O)CH2NCH3] o -R a ] v , -R b -[R e -(OCH2CH2) q -R c -R f -(OCH2CH2) q -R a ] v or -R b -[R e -[C(O)CH2NCH3] o -R c -R f -(OCH2CH2) q -R a ]v v is selected from 1 or 2, o is an integer from 1 to 20, and q is an integer from 1 to 20;

[0039] Among them, 1)R b Selected from the bond or -AA-, where -AA- is selected from 1 to 5 amino acid residues;

[0040] R e Selected from key, C 1-12 Alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 Alkylene-NR d -、-C(O)-C 1-12 alkylene-, -C 1-12 Alkylene -C(O)-, -C 1-12 Alkylene-NR d -C(O)-、-C 1-12 Alkylene-C(O)-NR d -C(O)-、-C 1-12 Alkylene-NR d -C(O)-C 1-12 Alkylene-, -NR d -C 1-12 Alkylene -C(O)-, -C(O)-C 1-12 Alkylene-NR d -or-NR d -C(O)-;

[0041] R c Selected from the bond or -BB-, where -BB- is selected from 1 to 5 peptide residues composed of amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, and aspartic acid.

[0042] R f Selected from key, C 1-12 Alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 Alkylene-NR d -、-C(O)-C 1-12 alkylene-, -C 1-12 Alkylene -C(O)-, -C 1-12 Alkylene-NR d -C(O)-、-C 1-12 Alkylene-C(O)-NR d -C(O)-、-C 1-12 Alkylene-NR d -C(O)-C 1-12 Alkylene-, -NRd -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0043] R d selected from hydrogen or C 1-6 alkyl;

[0044] R a selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0045] or 2) R b selected from ortho linker " " is the connecting end to Lp, A7 and A8 are the connecting bonds to R e ;

[0046] R e selected from bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0047] R c selected from bond or -BB-, -BB- is selected from a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0048] R f selected from bond, C 1-12 alkylene, -C(O)-, -NR d -C1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0049] R d is selected from hydrogen or C 1-6 alkyl;

[0050] R a is selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0051] R 12 are each independently selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl.

[0052] In some embodiments, "amino acid" refers to an organic compound that contains an amino group and a carboxyl group in its molecular structure, and both the amino and carboxyl groups are directly attached to a -CH- structure.

[0053] In some embodiments, R b is selected from -AA-, -AA- is selected from a peptide residue of 1 to 5 amino acid residues, including but not limited to phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, or a derivative thereof.

[0054] In some embodiments, the hydrophilic unit in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is -R b -[R e -(OCH2CH2) q -R c -R f -[C(O)CH2NCH3] o -Ra ] v , -R b - [R e - (OCH2CH2) q - R c - R f- (OCH2CH2) q - R a ] v or -R b - [R e - [C(O)CH2NCH3] o - R c - R f - (OCH2CH2) q - R a ] v , v is selected from 1 or 2, o is an integer from 1 to 20, q is an integer from 1 to 20;

[0055] wherein 1) R b is selected from a bond or -AA-, -AA- is selected from 1 to 5 amino acid residues;

[0056] R e is selected from a bond, C1x 12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0057] R c is selected from a bond or -BB-, -BB- is selected from 1 to 5 peptide residues selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0058] R f is selected from a bond, C1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0059] R d is selected from hydrogen or C 1-6 alkyl;

[0060] R a is selected from C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0061] or 2) R b is selected from a direct bond "*" is the point of attachment to Lp, A7and A8are the points of attachment to R e ;

[0062] R e is selected from a direct bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NRd -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0063] R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 amino acid residues of a peptide consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0064] R f is selected from the group consisting of a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0065] R d is selected from the group consisting of hydrogen or C 1-6 alkyl;

[0066] R a is selected from the group consisting of C 1-6 alkyl, C1-6alkoxy and C 3-6 cycloalkyl;

[0067] R 12 are each independently selected from the group consisting of hydrogen, C1-6alkyl, C1-6alkoxy and C 3-6 cycloalkyl.

[0068] In some embodiments, R 12 are each independently selected from the group consisting of hydrogen.

[0069] In some embodiments, the hydrophilic unit in a compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, is -Rb -[R e -(OCH2CH2) q -R c -R f -[C(O)CH2NCH3] o -R a ] v -R b -[R e -(OCH2CH2) q -R c -R f- (OCH2CH2) q -R a ] v or -R b -[R e -[C(O)CH2NCH3] o -R c -R f -(OCH2CH2) q -R a ] v v is selected from 1 or 2, o is an integer from 1 to 20, and q is an integer from 1 to 20;

[0070] Among them, 1)R b Selected from the bond or -AA-, where -AA- is selected from 1 to 5 peptide residues composed of amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, and aspartic acid.

[0071] R e Selected from key, C 1-12 Alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 Alkylene-NR d -、-C(O)-C 1-12 alkylene-, -C 1-12 Alkylene -C(O)-, -C 1-12 Alkylene-NR d -C(O)-、-C 1-12 Alkylene-C(O)-NR d -C(O)-、-C 1-12 Alkylene-NR d -C(O)-C 1-12 Alkylene-, -NR d -C 1-12 Alkylene -C(O)-, -C(O)-C 1-12 Alkylene-NR d -or-NR d -C(O)-;

[0072] R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 amino acid residues of a peptide consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0073] R f is selected from the group consisting of a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, 1-12 -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0074] R d is selected from the group consisting of hydrogen or C 1-6 alkyl;

[0075] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0076] or 2) R b is selected from the group consisting of a direct bond “*” is the bond to Sp, A7and A8are the bonds to R e , respectively;

[0077] R e is selected from the group consisting of a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, 1-12 -C(O)-C 1-12alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0078] R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 amino acid residues of a peptide consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0079] R f is selected from the group consisting of a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0080] R d is selected from the group consisting of hydrogen or C 1-6 alkyl;

[0081] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl.

[0082] In some embodiments, the hydrophilic unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, is -R b -[R e -(OCH2CH2) q -R c -R f- [C(O)CH2NCH3] o -R a ] v , -R b -[R e -(OCH2CH2) q -R c -R f- (OCH2CH2) q -R a ] v or -R b -[R e -[C(O)CH2NCH3] o -R c -R f -(OCH2CH2) q -R a ] v wherein R b , R e , R c , R f , q, o, v are as defined above; R a is selected from hydrogen.

[0083] In some embodiments, the hydrophilic unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, is

[0084] wherein,

[0085] 1) R b is selected from a bond or -AA-, R c is selected from a bond or -BB-, -AA- is selected from a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, and -BB- is selected from a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0086] R d is selected from hydrogen or C1-6alkyl; R a is selected from hydrogen, C1-6alkyl, C1-6alkoxy, and C 3-6 cycloalkyl; v is selected from 1 or 2;

[0087] o is selected from an integer from 1 to 20, q is selected from an integer from 1 to 20, and n is selected from an integer from 0 to 12.

[0088] or 2) R b selected from the group consisting of a direct bond or -BB-, -BB- is selected from the group consisting of a peptide residue of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; “*” is the connecting end with Lp, A7 and A8 are the connecting bonds with -C(O)-, respectively;

[0089] R c selected from the group consisting of a direct bond or -BB-, -BB- is selected from the group consisting of a peptide residue of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0090] R d selected from the group consisting of hydrogen or C 1-6 alkyl;

[0091] R a selected from the group consisting of hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0092] v is selected from 1 or 2;

[0093] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0094] In some embodiments, the hydrophilic unit in the compound of formula IA or la, or a pharmaceutically acceptable salt thereof, is

[0095] wherein 1) R b selected from the group consisting of a direct bond or -AA-, R c selected from the group consisting of a direct bond or -BB-, -AA- is selected from the group consisting of a peptide residue of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, -BB- is selected from the group consisting of a peptide residue of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0096] R d selected from the group consisting of hydrogen or C 1-6 alkyl;

[0097] R a selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0098] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0099] or 2) R b selected from the group consisting of a direct bond or -BB-, -BB- is selected from the group consisting of a peptide residue of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; " is the bond to Sp, A7 and A8 are the bonds to -C(O)-, respectively;

[0100] R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of a peptide residue of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0101] R d is selected from the group consisting of hydrogen or C 1-6 alkyl;

[0102] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0103] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0104] In some embodiments, the hydrophilic unit in a compound of formula IA or la, or a pharmaceutically acceptable salt thereof, is wherein R b , R e , R c , R f , q, o, v are as defined above; R a is selected from the group consisting of hydrogen.

[0105] In some embodiments, the hydrophilic unit in a compound of formula IA or la, or a pharmaceutically acceptable salt thereof, is

[0106] wherein 1) R b is selected from the group consisting of a bond or -AA-, -AA- is selected from the group consisting of a peptide residue of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of a peptide residue of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0107] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0108] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0109] or 2) R b is selected from the group consisting of an orthogonal linker "*" is the end connected with Sp, A7 and A8 are the bonds connected with -C(O)- respectively;

[0110] R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 peptide residues of amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0111] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0112] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0113] In some embodiments, the compound of Formula la or a pharmaceutically acceptable salt thereof, the hydrophilic unit is

[0114] wherein 1) R b is selected from the group consisting of a bond or -AA-, -AA- is selected from the group consisting of 1 to 5 peptide residues of amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 peptide residues of amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0115] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0116] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0117] or 2) R b is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 peptide residues of amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; "*" is the end connected with Lp, A7 and A8 are the bonds connected with -C(O)- respectively;

[0118] R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 peptide residues of amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0119] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C3-6 cycloalkyl;

[0120] o is an integer from 1 to 20, q is an integer from 1 to 20, and n is an integer from 0 to 12.

[0121] In some embodiments, the hydrophilic unit in the compound of formula IA or Ia or its druggable salt is Where R b R e R c R f , q, o, v as defined above; R a Selected from hydrogen.

[0122] In other embodiments, the hydrophilic unit in the compound of formula IA or Ia or its pharmaceutically acceptable salt is... Where o is an integer from 1 to 20, q is an integer from 1 to 20, and R a Selected from C 1- 6-alkyl, C 1-6 Alkoxy and C 3-6 Cycloalkyl.

[0123] In some embodiments, the hydrophilic unit in the compound shown in Ia or its druggable salt is Where o is an integer from 1 to 20, q is an integer from 1 to 20, and R a Selected from C 1-6 Alkyl, C 1-6 Alkoxy and C 3-6 Cycloalkyl.

[0124] In some embodiments, the hydrophilic unit in the compound shown in Ia or its druggable salt is selected from:

[0125] Where R a Selected from C 1-6 Alkyl, C 1-6 Alkoxy and C 3-6 cycloalkyl; R d Selected from hydrogen or C 1-6 Alkyl; o is an integer from 1 to 20, q is an integer from 1 to 20, and n is an integer from 0 to 12.

[0126] On the other hand, the hydrophilic unit in the compound of formula IA or Ia or its druggable salt is selected from:

[0127] in" * "For S" p Connecting end; R cis selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 amino acid residues selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0128] R d is selected from the group consisting of hydrogen or C 1-6 alkyl;

[0129] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0130] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0131] In some embodiments, the hydrophilic unit in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from the group consisting of:

[0132] wherein "*" is the point of attachment to Sp; R c , R d , o is as defined above, R a is selected from the group consisting of hydrogen.

[0133] In some embodiments, the hydrophilic unit in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from the group consisting of:

[0134] wherein "*" is the point of attachment to Sp; R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl; o is an integer from 1 to 20, q is an integer from 1 to 20.

[0135] In some embodiments, the hydrophilic unit in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from the group consisting of:

[0136] wherein "*" is the point of attachment to Sp; R a is selected from the group consisting of hydrogen; o is an integer from 1 to 20, q is an integer from 1 to 20.

[0137] In some embodiments, the hydrophilic unit in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from the group consisting of:

[0138] wherein "*" is the point of attachment to Sp; R a is selected from the group consisting of hydrogen; o is an integer from 1 to 20, q is an integer from 1 to 20.

[0139] In some embodiments, the hydrophilic unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, is selected from:

[0140] wherein "*" is the point of attachment to Sp; R a selected from hydrogen; o is an integer from 1 to 20, and q is an integer from 1 to 20.

[0141] In other embodiments, the value of o+q in the hydrophilic group is from 8 to 13. In some embodiments, the value of o+q in the hydrophilic group is 12. In some embodiments, the value of o+q in the hydrophilic group is 11. In some embodiments, the value of o+q in the hydrophilic group is 10.

[0142] In some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, comprises a peptide residue consisting of 2 to 7 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, arginine.

[0143] In some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, comprises a peptide residue consisting of lysine, valine, and arginine.

[0144] In some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, comprises a peptide residue consisting of lysine, alanine, and alanine.

[0145] In some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, comprises a peptide residue consisting of lysine, valine, and lysine.

[0146] In some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, comprises valine-arginine (Val-Arg), valine-alanine (Val-Ala), valine-citrulline (Val-Cit), glycine-glycine-phenylalanine-glycine (Gly-Gly-Phe-Gly), glycine-glycine-valine-alanine (Gly-Gly-Val-Ala), glycine-glycine-valine-citrulline (Gly-Gly-Val-Cit), alanine-alanine (Ala-Ala), valine-lysine (Val-Lys).

[0147] In some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, comprises lysine-valine-arginine (Lys-Val-Arg).

[0148] In some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, comprises lysine-valine-alanine (Lys-Val-Ala).

[0149] In some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, comprises lysine-alanine-alanine (Lys-Ala-Ala).

[0150] In some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, comprises lysine-valine-lysine (Lys-Val-Lys).

[0151] In another aspect, in some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, further comprises -(CH2CH20)n1-C2alkylene-C(O)- or -[C(O)CH2NCH3]n2- n1 -C 1-2 alkylene-C(O)- or -[C(O)CH2NCH3] n2 wherein n1, n2 are integers from 1 to 10.

[0152] In some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, further comprises -(CH2CH20)2-C2alkylene-C(O)-, -(CH2CH20)3-C2alkylene-C(O)- or -(CH2CH20)4-C2alkylene-C(O)-.

[0153] In some embodiments, the amino acid unit in the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, comprises the following moiety: wherein W is -NH-heterocycloalkyl- or heterocycloalkyl; Y is heteroaryl, aryl, -C(O)C 1-6 alkylene, C 2-6 alkenylene, C 1-6 alkylene or -C 1-6 alkylene-NH-; each R 5 is independently selected from C 1-10 alkyl, C 2-10 alkenyl, C 1-6 alkylene-NH2, -(C 1-10 alkylene)NHC(NH)NH2 or -(C 1-10 alkylene)NHC(O)NH2; R 6 and R 7 are each independently H, C 1-10 alkyl, C 2-10 alkenyl, arylalkyl, heteroarylalkyl, or R 6 and R 7 together can form a C 3-7 cycloalkyl or 3-7 membered heterocycloalkyl.

[0154] In some embodiments, the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, is selected from

[0155] In other embodiments, the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, the amino acid unit comprises a lysine residue.

[0156] In some embodiments, the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, the hydrophilic unit is attached to a lysine residue in the amino acid unit.

[0157] In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is 2 and L 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; Ai is a bond to the L terminus, A2, A7 are bonds to the D terminus, A3 is a bond to the U terminus; R 17 is selected from the group consisting of hydrogen, C 1-6 alkyl, haloC 1-6 alkyl or a hydrophilic group U, for example hydrogen, methyl, trifluoromethyl or a hydrophilic group U.

[0158] In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is 2 and L 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; Ai is a bond to the L terminus, A2, A7 are bonds to the D terminus, A3 is a bond to the U terminus.

[0159] In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is 2 and L 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; Ai is a bond to the L terminus, A2, A7 are bonds to the D terminus, A3 is a bond to the U terminus.

[0160] ​​​​​​​​​In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is is B is L 2 and L 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, and A3is a bond to the U terminus.

[0161] In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is is B is L 3 and L 17 is selected from the group consisting of hydrogen, C 1-6 alkyl, haloC 1-6 alkyl or a hydrophilic group U, for example hydrogen, methyl, trifluoromethyl or a hydrophilic group U.

[0162] In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is is B is L 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, and A3is a bond to the U terminus.

[0163] In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is is B is L 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, and A3is a bond to the U terminus.

[0164] In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is is B is L 3each comprising a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus.

[0165] In some embodiments, the compound of formula Ia or a pharmaceutically acceptable salt thereof is B is L 2 , L 3 each comprising a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus; R 17 is selected from the group consisting of hydrogen, C 1-6 alkyl, haloC 1-6 alkyl or a hydrophilic group U, for example hydrogen, methyl, trifluoromethyl or a hydrophilic group U.

[0166] In some embodiments, the compound of formula Ia or a pharmaceutically acceptable salt thereof is B is L 2 , L 3 each comprising a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus.

[0167] In some embodiments, the compound of formula IA or a pharmaceutically acceptable salt thereof is B is L 2 , L 3 each comprising a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus.

[0168] In some embodiments, the compound of formula IA or a pharmaceutically acceptable salt thereof is B is L 2 , L 3 ​​​​each comprising a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus.

[0169] In some embodiments, L 3 comprises a peptide residue consisting of valine and arginine.

[0170] In some embodiments, L 3 comprises a peptide residue consisting of alanine and alanine.

[0171] In some embodiments, L 3 comprises a peptide residue consisting of valine and lysine.

[0172] In some embodiments, L 3 comprises a peptide residue consisting of valine and alanine.

[0173] In some embodiments, L 3 selected from valine-citrulline (Val-Cit), valine-alanine (Val-Ala), phenylalanine-citrulline (Phe-Cit), alanine-phenylalanine (Ala-Phe), phenylalanine-arginine (Phe-Arg), phenylalanine-lysine (Phe-Lys), valine-lysine (Val-Lys), alanine-citrulline (Ala-Cit), alanine-arginine (Ala-Arg), alanine-glutamic acid (Ala-Glu), valine-glutamic acid (Val-Glu), valine-arginine (Ala-Arg), phenylalanine-homolysine (Phe-Homolys), n-methyl-valine-citrulline (Me-Val-Cit), alanine-alanine (Ala-Ala), glycine-glutamic acid (Gly-Glu), glutamic acid-alanine-alanine (Glu-Ala-Ala), and glycine-lysine (Gly-Lys), glycine-valine-citrulline (Glv-Val-Cit), glycine-glycine-glycine (Gly-Gly-Gly), glycine-glycine-phenylalanine-glycine (Gly-Gly-Phe-Gly).

[0174] In some embodiments, L 3 selected from valine-arginine (Val-Arg).

[0175] In some embodiments, L 3 selected from glycine-glycine-phenylalanine-glycine (Gly-Gly-Phe-GLy).

[0176] In some embodiments, L 3 is selected from alanine-alanine (Ala-Ala).

[0177] In some embodiments, L 3 is selected from valine-lysine (Val-Lys).

[0178] In some embodiments, L 3 is selected from valine-alanine (Val-Ala).

[0179] In some embodiments, the compound of formula la or a pharmaceutically acceptable salt thereof is wherein B is wherein B is L 2 comprising a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; Ai is a bond to the L terminus, A2, A7 are bonds to the D terminus, A3 is a bond to the U terminus; R 17 is selected from hydrogen, C 1-6 alkyl, haloC 1-6 alkyl or a hydrophilic group U, for example hydrogen, methyl, trifluoromethyl or a hydrophilic group U.

[0180] In some embodiments, the compound of formula la or a pharmaceutically acceptable salt thereof is wherein B is wherein B is L 2 comprising a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; Ai is a bond to the L terminus, A2, A7 are bonds to the D terminus, A3 is a bond to the U terminus.

[0181] In some embodiments, the compound of formula la or a pharmaceutically acceptable salt thereof is wherein B is wherein B is L 2 comprising a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; Ai is a bond to the L terminus, A2, A7 are bonds to the D terminus, A3 is a bond to the U terminus.

[0182] In some embodiments, the compound of formula la or a pharmaceutically acceptable salt thereof is wherein B is wherein B is L 2comprises a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus.

[0183] In some embodiments, L 2 comprises a peptide residue consisting of valine and arginine.

[0184] In some embodiments, L 2 comprises a peptide residue consisting of alanine and alanine.

[0185] In some embodiments, L 2 comprises a peptide residue consisting of valine and lysine.

[0186] In some embodiments, L 2 comprises a peptide residue consisting of valine and alanine.

[0187] In some embodiments, L 2 selected from the group consisting of valine-citrulline (Val-Cit), valine-alanine (Val-Ala), phenylalanine-citrulline (Phe-Cit), alanine-phenylalanine (Ala-Phe), phenylalanine-arginine (Phe-Arg), phenylalanine-lysine (Phe-Lys), valine-lysine (Val-Lys), alanine-citrulline (Ala-Cit), alanine-arginine (Ala-Arg), alanine-glutamic acid (Ala-Glu), valine-glutamic acid (Val-Glu), valine-arginine (Ala-Arg), phenylalanine-homolysine (Phe-Homolys), n-methyl-valine-citrulline (Me-Val-Cit), alanine-alanine (Ala-Ala), glycine-glutamic acid (Gly-Glu), glutamic acid-alanine-alanine (Glu-Ala-Ala), and glycine-lysine (Gly-Lys), glycine-valine-citrulline (Glv-Val-Cit), glycine-glycine-glycine (Gly-Gly-Gly), glycine-glycine-phenylalanine-glycine (Gly-Gly-Phe-Gly). In some embodiments, L 2 selected from the group consisting of valine-arginine (Val-Arg). In some embodiments, L 2 selected from the group consisting of glycine-glycine-phenylalanine-glycine (Gly-Gly-Phe-GLy). In some embodiments, L 2 selected from the group consisting of alanine-alanine (Ala-Ala). In some embodiments, L 2selected from valine-lysine (Val-Lys). In some embodiments, L 2 selected from valine-alanine (Val-Ala).

[0188] In other embodiments, the compound of Formula la, or a pharmaceutically acceptable salt thereof, is B is A1is a bond to the L terminus, A2, A7are bonds to the D terminus, and A3is a bond to the U terminus; R 17 selected from hydrogen, C 1-6 alkyl, haloC 1-6 alkyl, or a hydrophilic group U, such as hydrogen, methyl, trifluoromethyl, or a hydrophilic group U.

[0189] In other embodiments, the compound of Formula la, or a pharmaceutically acceptable salt thereof, is B is A1is a bond to the L terminus, A2, A7are bonds to the D terminus, and A3is a bond to the U terminus.

[0190] In some embodiments, the compound of Formula la, or a pharmaceutically acceptable salt thereof, is B is A1is a bond to the L terminus, A2, A7are bonds to the D terminus, and A3is a bond to the U terminus.

[0191] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, the hydrophilic unit is attached to a glutamic acid residue in the amino acid unit.

[0192] In some embodiments, the compound of Formula la, or a pharmaceutically acceptable salt thereof, is B is L 2 and L 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, and A3is a bond to the U terminus; R 17 selected from hydrogen, C 1-6 alkyl, haloC 1-6 alkyl, or a hydrophilic group U, such as hydrogen, methyl, trifluoromethyl, or a hydrophilic group U.

[0193] In some embodiments, L 2 or L 3 also comprises -(CH2CH20) n1 -C​​​​1-2 alkylene-C(O)- or -[C(O)CH2NCH3] n2 - wherein n1, n2 are integers from 1 to 10.

[0194] In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is selected from the following structures:

[0195] wherein R 17 is selected from hydrogen, C 1-6 alkyl, haloC 1-6 alkyl or a hydrophilic group U, such as hydrogen, methyl, trifluoromethyl or a hydrophilic group U; A1 is a bond to the L terminus, A7 is a bond to the D terminus; n1 is an integer from 1 to 10 (e.g., 2, 3, 4, 5, 6, 8, or 9).

[0196] In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is selected from:

[0197] wherein A1 is a bond to the L terminus, A7 is a bond to the D terminus; wherein n1 is an integer from 1 to 10 (e.g., 2, 3, 4, 5, 6, 8, or 9); U is a hydrophilic group.

[0198] In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is selected from the following structures:

[0199] wherein A1 is a bond to the L terminus, A7 is a bond to the D terminus; U is a hydrophilic group.

[0200] In some embodiments, the compound of Formula Ia, or a pharmaceutically acceptable salt thereof, is selected from the following structures:

[0201] wherein A1 is a bond to the L terminus, A7 is a bond to the D terminus; U is a hydrophilic group.

[0202] In another aspect, in some embodiments, L 2 or L 3 also comprises an orthogonal linker, which is commonly used in the art, such as an amino acid or mentioned in the present disclosure.

[0203] In some embodiments, the compound of Formula IA or Ia, or a pharmaceutically acceptable salt thereof, R comprises / is selected from the following group: optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted and optionally substituted wherein each E is independently selected from a leaving group, such as halo; r is selected from an integer from 1-6, such as 3 and 4; is a bond or is absent.

[0204] In other embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from: wherein E is selected from a leaving group (e.g., halo: bromo).

[0205] In some embodiments, R is selected from optionally substituted

[0206] In some embodiments, R is selected from optionally substituted

[0207] In some embodiments, the optional substituents of R are selected from one or more of the following: halo, hydroxyl, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy. In some embodiments, the optional substituents of R are selected from C 1-6 alkyl (e.g., methyl or ethyl). In some embodiments, the optional substituents of R are selected from halo (e.g., F or Br).

[0208] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from:

[0209] In other embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from: 8 -L 1 -, wherein R 8selected from -W1-C(O)-, -C(O)-W1-C(O)-, -(CH2CH2O) p C(O)-, -W1-(CH2CH2O) p C(O)-, -W1-(CH2CH2O) p CH2C(O)-, -W1-(CH2CH2O) p CH2CH2C(O)-, -(CH2CH2O) p CH2C(O)-, -(CH2CH2O) p CH2CH2C(O)-, wherein W1is selected from C 1-8 alkylene, C6aryl, C 5-6 heteroaryl, C 1-8 alkylene-cycloalkyl or straight chain heteroalkylene of 1 to 8 atoms, which heteroalkylene contains 1 to 3 heteroatoms selected from N, O, or S, wherein said C 1-8 alkylene, C6aryl, C 5-6 heteroaryl, cycloalkyl and straight chain heteroalkylene are each independently optionally further substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy;

[0210] L 1 selected from -NR 9 (CH2CH2O) p CH2CH2C(O)-, -NR 9 (CH2CH2O) p CH2C(O)-, -S(CH2) p C(O)-, -(CH2) p C(O)- or a bond;

[0211] wherein each p is independently selected from an integer from 1 to 20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15), and each R 9 is independently selected from a hydrogen atom and C 1-8 alkyl, said C 1-8 alkyl is optionally substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkoxy. In some embodiments, in a compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, L 1 is selected from a bond.

[0212] In some embodiments, in a compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, R 8 is selected from -C 1-6Alkylenes -C(O)-, -(CH2-CH2O)2C(O)-, -(CH2-CH2O)2CH2C(O)-, -(CH2-CH2O)2CH2CH2C(O)-, -(CH2-CH2O)3C(O)- and -(CH2-CH2O)4C(O)-.

[0213] In other embodiments, R in the compound of formula IA or Ia or its pharmaceutically acceptable salt 8 Selected from -C 1-8 Alkylene-cyclohexylene-C(O)-, -(CH2-CH2O)4CH2C(O)- and -(CH2-CH2O)6CH2C(O)-.

[0214] In some embodiments, W1 is selected from C6 aryl or C6 aryl. 5-6 Heteroaryl, the C6 aryl or C 5-6 Each heteroaryl group is independently and optionally further selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 Alkyl or C 1-6 It is replaced by one or more substituents of the alkoxy group.

[0215] In some embodiments, L in the compound of formula IA or Ia or its pharmaceutically acceptable salt contains -R 8 -L 1 -, R 8 Selected from -W1-(CH2CH2O) p C(O)-、-W1-(CH2CH2O) p CH2C(O)-、-W1-(CH2CH2O) p CH2CH2C(O)-, W1 is selected from C6 aryl, C 5-6 Heteroaryl, the C6 aryl or C 5-6 Each heteroaryl group is independently and optionally further selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 Alkyl or C 1-6 The alkoxy group is substituted by one or more substituents, L 1 Selected from key.

[0216] In some embodiments, R in the compound of formula IA or Ia or its pharmaceutically acceptable salt 8 Selected from phenyl, said phenyl optionally coated with one or more halogens, C 1-6 Alkyl groups are substituted.

[0217] In some embodiments, R in the compound of formula IA or Ia or its pharmaceutically acceptable salt 8 Selected from * Connect to R, ** Connect to L 1 Connected.

[0218] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is 8 selected from p is selected from an integer from 1 to 20, for example, 3 or 4; the * end is attached to R; the ** end is attached to L1.

[0219] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is 8 selected from p is selected from an integer from 1 to 20, for example, 3 or 4; the * end is attached to R; the ** end is attached to L1.

[0220] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is 16 -(CH2CH2O)4CH2CH2C(O)-, wherein R p C(O)-, -N(R 16 -(CH2CH2O)4CH2C(O)-, -N(R p -(CH2CH2O)4CH2CH2C(O)-, wherein R 16 -(CH2CH2O)4CH2CH2C(O)-, wherein R p CH2CH2C(O)-, wherein R 16 is selected from hydrogen, C 1-6 alkyl or haloC 1-6 alkyl, each p is independently selected from an integer from 1 to 20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15).

[0221] In other embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is 8 -L 1 -, R 8 , L 1 as previously defined.

[0222] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is 16 -(CH2CH2O)4CH2CH2C(O)-, wherein R 16 -(CH2CH2O)4CH2C(O)-, -N(R 16 -(CH2CH2O)4CH2CH2C(O)-, wherein R 16 is selected from hydrogen, C 1-6 alkyl or haloC 1-6 alkyl.

[0223] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is p C(O)-, -O(CH2CH2O) p CH2C(O)-, -O(CH2CH2O)p CH2CH2C(O)-, wherein each p is independently selected from an integer from 1 to 20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15).

[0224] In some embodiments, L in the compound of Formula IA or la is selected from -O(CH2CH2O)4C(O)-, -0-(CH2CH2O)4CH2C(O)-, -0(CH2CH2O)4CH2CH2C(O)-.

[0225] In another aspect, in some embodiments, L in the compound of Formula IA or la further comprises wherein each of h or j is independently selected from 0 or 1; R 104 each is independently selected from hydrogen or C 1-3 alkyl.

[0226] In some embodiments, L in the compound of Formula IA or la comprises

[0227] In some embodiments, L in the compound of Formula IA or la comprises

[0228] In some embodiments, L in the compound of Formula IA or la is selected from p3 is selected from 0, 1, 2, 3, and 4.

[0229] In some embodiments, a = 1 in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof.

[0230] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is a compound of Formula I-1, or a pharmaceutically acceptable salt thereof

[0231] In another aspect, the present disclosure provides a compound, or a pharmaceutically acceptable salt thereof, wherein L 2 further comprises an orthogonal linker, allowing (U) to be in an orthogonal direction relative to (X-D).

[0232] In some embodiments, the orthogonal linker is selected from:

[0233] t is 0, 1, 2, or 3, A4 is a bond to the B terminus, A5 and A6 are bonds to the -X-D terminus.

[0234] In some embodiments, L in the compound, or a pharmaceutically acceptable salt thereof, is 2 comprises t is 0, 1, 2 or 3, A4is a bond to the B terminus, A5and A6are bonds to the -X-D terminus.

[0235] In some embodiments, the compound or pharmaceutically acceptable salt thereof is 3 comprising t is 0, 1, 2 or 3, A4is a bond to the B terminus, A5and A6are bonds to the -X-D terminus.

[0236] In some embodiments, the compound or pharmaceutically acceptable salt thereof is 2 or L 3 comprising A4is a bond to the B terminus, A5and A6are bonds to the -X-D terminus.

[0237] In some embodiments, the compound or pharmaceutically acceptable salt thereof is 2 or L 3 comprising A4is a bond to the B terminus, A5and A6are bonds to the -X-D terminus.

[0238] In some embodiments, the compound or pharmaceutically acceptable salt thereof is 2 or L 3 comprising A4is a bond to the B terminus, A5and A6are bonds to the -X-D terminus.

[0239] In some embodiments, the compound of Formula IA or la, or pharmaceutically acceptable salt thereof, is a compound of Formula I-2, or pharmaceutically acceptable salt thereof wherein R, L, U, X and D are as defined in the compound of Formula IA or la; B is A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus; t is 0, 1 or 2.

[0240] In some embodiments, the compound of Formula IA or la, or pharmaceutically acceptable salt thereof, is a compound of Formula I-3, or pharmaceutically acceptable salt thereof wherein R, L, U, X and D are as defined in the compound of Formula IA or la; B is A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus; t is 0, 1, 2 or 3; L 4 comprising a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid.

[0241] In some embodiments, the compound of Formula IA or la, or pharmaceutically acceptable salt thereof, is a compound of Formula I-4, or pharmaceutically acceptable salt thereof wherein R, L, U, X and D are as defined in the compound of Formula IA or la; B is A1is the bond to the L terminus, A2, A7are the bonds to the D terminus, and A3is the bond to the U terminus; L 4 comprising a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid.

[0242] In some embodiments, the orthogonal linker is selected from:

[0243] wherein each t1is independently selected from 0, 1, 2, 3 or 4; each t2is independently selected from 1, 2, 3 or 4; A4is the bond to the B terminus, A5and A6are the bonds to the -X-D terminus.

[0244] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is a compound of Formula I-5, or a pharmaceutically acceptable salt thereof wherein R, L, U, X and D are as defined in the compound of Formula IA or la; B is A1is the bond to the L terminus, A2, A7are the bonds to the D terminus, and A3is the bond to the U terminus; t is 0, 1, 2 or 3; L 4 comprising a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid.

[0245] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is a compound of Formula I-6, or a pharmaceutically acceptable salt thereof wherein R, L, U, X and D are as defined in the compound of Formula IA or la; B is A1is the bond to the L terminus, A2, A7are the bonds to the D terminus, and A3is the bond to the U terminus; t is 0, 1, 2 or 3; L 4 comprising a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid.

[0246] In another aspect, the disclosure provides that the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from a cytotoxic compound, such as eribulin or an analog thereof, trabectedin or an analog thereof, austinin E or an analog thereof, austinin F or an analog thereof, camptothecin or an analog thereof, cabazitaxel or an analog thereof.

[0247] The disclosure provides that the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, can also be selected from a glucocorticoid (such as budesonide or a derivative thereof).

[0248] In some embodiments, the drug unit D in the present disclosure is selected from

[0249] In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is

[0250] In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is

[0251] In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is

[0252] In another aspect, the hydrophilic unit U is attached to the spacer unit X in the compound of Formula IA, or a pharmaceutically acceptable salt thereof, in the present disclosure. In some embodiments, the compound of Formula IA, or a pharmaceutically acceptable salt thereof, is a compound of Formula IB, or a pharmaceutically acceptable salt thereof,

[0253] wherein D is a drug unit; X is a spacer unit; Lp is an amino acid unit; U is a hydrophilic unit comprising polyethylene glycol structural units and polysarcosine structural units; L is a linker unit; R is a linking group; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0254] In some embodiments, the compound of Formula IB, or a pharmaceutically acceptable salt thereof, is wherein G is selected from a bond, -0-, -C(O)-, -(CR 10 R 11 ) g N(R cc )-, -S-, -S(O)-, -S(O)2-, -S(O)2-C 1-6 alkylene-, -S(O)2-C 2-6 alkylene-, -S(O)2-C

[0255] R 10 and R 11 are the same or different and each is independently selected from hydrogen, a deuterium atom, halogen, or alkyl;

[0256] R aa is selected from hydrogen or C 1-6 alkyl;

[0257] R bb is selected from halogen or C 1-6 alkyl;

[0258] R cc is selected from hydrogen or C 1-6 alkyl;

[0259] A1is a bond to the Lp terminus and A2is a bond to the D terminus;

[0260] v is selected from 0, 1, 2, 3, or 4; g is selected from 0, 1, 2, or 3;

[0261] U is a hydrophilic unit comprising polyethylene glycol structural units and poly sarcosine structural units.

[0262] In some embodiments, the compound of Formula IB, or a pharmaceutically acceptable salt thereof, is wherein wherein R aa , R bb , A1, A2, v, and G are as previously defined; U is a hydrophilic unit comprising polyethylene glycol structural units and poly sarcosine structural units.

[0263] In some embodiments, the compound of Formula IB, or a pharmaceutically acceptable salt thereof, is selected from: wherein A1is a bond to the Lp terminus and A2is a bond to the D terminus; U is a hydrophilic unit comprising polyethylene glycol structural units and poly sarcosine structural units.

[0264] or a pharmaceutically acceptable salt thereof, wherein is selected from wherein A1is a bond to the Lp terminus, A2is a bond to the D terminus; U is a hydrophilic unit comprising polyethylene glycol structural units and polysarcosine structural units.

[0265] In some embodiments, the compound of Formula IB or a pharmaceutically acceptable salt thereof is a compound of Formula IB-1 or a pharmaceutically acceptable salt thereof wherein D, Lp, U, L, R are as defined in the compound of Formula IB.

[0266] In some embodiments, R in the compound of Formula IB or Formula IB-1 is selected from optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted wherein r is selected from an integer from 1-6, for example 3 and 4.

[0267] In some embodiments, L in the compound of Formula IB or Formula IB-1 comprises -R 8 -L 1 -, R 8 and L 1 are as defined above.

[0268] In some embodiments, L in the compound of Formula IB comprises -R 8 -L 1 -, R 8 is selected from -(CH2CH2O) p C(O)-, -(CH2CH2O) p CH2C(O)-, -(CH2CH2O) p CH2CH2C(O)-, each p is independently selected from an integer from 1 to 20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15).

[0269] In some embodiments, L in the compound of Formula IB or Formula IB-1 comprises -R 8 -L 1 -, R 8 is selected from -(CH2-CH2O)4CH2C(O)- and -(CH2-CH2O)6CH2C(O)-, L 1 is selected from a bond.

[0270] In some embodiments, L in the compound of Formula IB is selected from -N(R 16 )-(CH2CH2O)p C(O)-, -N(R 16 )-(CH2CH2O) p CH2C(O)-, -N(R 16 )-(CH2CH2O) p CH2CH2C(O)-, wherein R 16 is selected from hydrogen, C 1-6 alkyl or halogenated C 1-6 alkyl, each p is independently selected from an integer from 1 to 20 (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15).

[0271] In some embodiments, L is selected from -N(R 16 )-(CH2CH2O)4C(O)-, -N(R 16 )-(CH2CH2O)4CH2C(O)-, -N(R 16 )-(CH2CH2O)4CH2CH2C(O)-, wherein R 16 is selected from hydrogen, C 1-6 alkyl or halogenated C 1-6 alkyl.

[0272] In some embodiments, the amino acid unit in the compound of Formula IB or Formula IB-1 comprises a peptide residue consisting of 2 to 7 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, arginine.

[0273] In some embodiments, the amino acid unit in the compound of Formula IB or Formula IB-1 comprises valine-arginine (Val-Arg), valine-alanine (Val-Ala), valine-citrulline (Val-Cit), glycine-glycine-phenylalanine-glycine (Gly-Gly-Phe-Gly), glycine-glycine-valine-alanine (Gly-Gly-Val-Ala), glycine-glycine-valine-citrulline (Gly-Gly-Val-Cit), alanine-alanine (Ala-Ala), valine-lysine (Val-Lys).

[0274] In some embodiments, the drug unit D in the compound of Formula IB or Formula IB-1 is selected from a cytotoxic compound or a glucocorticoid, e.g., eribulin or an analog thereof, trabectedin or an analog thereof, methylauristatin E or an analog thereof, methylauristatin F or an analog thereof, camptothecin or an analog thereof, budesonide or a derivative thereof, cabazitaxel or an analog thereof.

[0275] In other embodiments, the compound of Formula IA, or a pharmaceutically acceptable salt thereof, is selected from the group consisting of a compound of Formula IIIA, or a pharmaceutically acceptable salt thereof wherein D is a drug unit; Sp is Lp-(X) b ; X is a spacer unit; Lp is an amino acid unit; U is a hydrophilic unit comprising polyethylene glycol building blocks and polysarcosine building blocks; L is a stretch unit; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and b is selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10;

[0276] R 8 is selected from -W1-C(O)-, -C(O)-W1-C(O)-, -W1-(CH2CH2O) p C(O)-, -W1-(CH2CH2O) p CH2C(O)-, -W1-(CH2CH2O) p CH2CH2C(O)-, -(CH2CH2O) p C(O)-, -(CH2CH2O) p CH2C(O)-, -(CH2CH2O) p CH2CH2C(O)-, wherein W1 is selected from C 1-8 alkylene, C6aryl, C 5-6 heteroaryl, C 1-8 alkylene-cycloalkyl, or a straight-chain heteroalkylene of 1 to 8 atoms, which heteroalkylene comprises 1 to 3 heteroatoms selected from N, O, or S, wherein the C1-8alkylene, C6aryl, C 5-6 heteroaryl, C1-8alkylene-cycloalkyl, and straight-chain heteroalkylene are each independently optionally further substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl, or C 1-6 alkoxy;

[0277] L 1 is selected from -NR 9 (CH2CH2O) p CH2CH2C(O)-, -NR9(CH2CH2O) p CH2C(O)-, -S(CH2) p C(O)-, -(CH2) p C(O)-, or a bond, preferably a bond;

[0278] wherein each p is independently selected from an integer from 1 to 20, and each R9 is independently selected from a hydrogen atom and a C 1-8 alkyl, said C 1- 8alkyl is optionally substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C1-6 One or more substituents in the alkoxy group are substituted; each E is independently selected from leaving groups, such as halogens; It is either a chemical bond or does not exist.

[0279] In some embodiments, the compound represented by formula IIIA or formula Ia, or a pharmaceutically acceptable salt thereof, is used. Among them D, Lp, X, U, L, a, R 8 L 1 E As defined in the compound shown in Formula IIIA.

[0280] In some embodiments, the compound represented by formula IIIA or formula IB, or a pharmaceutically acceptable salt thereof, is the compound represented by formula IIIb, or a pharmaceutically acceptable salt thereof. Among them D, Lp, X, U, L, a, R 8 L 1 E As defined in the compound shown in Formula IIIA.

[0281] In some embodiments, E is selected from halogens or ArS-, and Ar is selected from substituted or unsubstituted C. 6-10 Substituted or unsubstituted 5-12 heteroaryl groups.

[0282] In some implementations, Ar is selected from phenyl, halobenzene, C 1-4 Alkylphenyl, C 1-4 alkoxyphenyl, 2-pyridyl, 2-pyrimidinyl, 1-methylimidazol-2-yl or Where R 13 R 14 Each is independently selected from hydrogen and C. 1-6 Alkyl, C 1-6 Alkoxy, amino, C 3-6 cycloalkyl, C 3-6 Heterocyclic alkyl, the C 1-6 Alkyl, C 1-6 Alkoxy, amino, C 3- 6-cycloalkyl, C 3-6 Heterocyclic alkyl groups may optionally be further selected from halogen, hydroxyl, cyano, nitro, oxo, amino, C 1-6 Alkyl or C 1-6 The alkoxy group is substituted by one or more substituents; or R 13 R 14 Form C with adjacent atoms 3-6 Heterocyclic alkyl, the C 3-6 Heterocyclic alkyl groups may optionally be further selected from halogen, hydroxyl, cyano, nitro, oxo, amino, C 1-6 Alkyl or C 1-6substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy.

[0283] In some embodiments, Ar is selected from R 13 , R 14 and the adjacent atoms form a C3-8cycloalkyl, C3-8cycloalkenyl or C6-10aryl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy. 3-6 heterocycloalkyl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy. 3-6 heterocycloalkyl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy. 1-6 heterocycloalkyl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy. 1- heterocycloalkyl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy.

[0284] In some embodiments, Ar is selected from R 13 , R 14 and the adjacent atoms form a pyrrolidinyl or piperidinyl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy. 1- heterocycloalkyl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy. 1-6 heterocycloalkyl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy.

[0285] In some embodiments, Ar is selected from

[0286] In some embodiments, W1in a compound of Formula IIIA is selected from C6aryl or C1-6heteroaryl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy. 5-6 heteroaryl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy. 5-6 heteroaryl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy. 1-6 heteroaryl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy. 1-6 heteroaryl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy.

[0287] In some embodiments, a compound of Formula IIIA is a compound of Formula IIIA-1 or IIIA-2

[0288] wherein R 13 , R 14 , R 15 , z, D, Sp, U, a are as defined in a compound of Formula IIIA; each p4is independently selected from 0, 1, 2, 3 and 4.

[0289] In some embodiments, R 13 , R 14 and the adjacent atoms form a pyrrolidinyl or piperidinyl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy. 1-6 heterocycloalkyl, which is optionally further substituted with one or more substituents selected from halo, hydroxy, cyano, nitro, oxo, amino, C1-6alkyl or C1-6alkoxy.1-6 alkyl or C 15 selected from halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy; z is selected from 0, 1, 2, 3 or 4; D, Sp, U, a are defined as in the compound of formula IIIA.

[0290] In some embodiments, the compound of formula IIIA is selected from:

[0291] wherein each p4 is independently selected from 0, 1, 2, 3 and 4.

[0292] In some embodiments, the compound of formula IIIA or formula Ilia is selected from:

[0293] wherein each p4 is independently selected from 0, 1, 2, 3 and 4; X, D, U and a are defined as before.

[0294] In some embodiments, the amino acid unit in the compound of formula IIIA or formula Ilia comprises a peptide residue consisting of 2 to 7 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid. In some embodiments, the amino acid unit in the compound of formula IIIA or formula Ilia comprises a lysine residue. In some embodiments, the hydrophilic unit in the compound of formula IIIA or formula Ilia is attached to the lysine residue in the amino acid unit.

[0295] In some embodiments, the hydrophilic unit U in the compound of formula IIIA or formula Ilia is wherein,

[0296] 1) R b selected from a bond or -AA-, R c selected from a bond or -BB-, -AA- is selected from a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, -BB- is selected from a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0297] R d selected from hydrogen or C 1-6 alkyl; R a selected from hydrogen, C1-6 Alkyl, C 1-6 Alkoxy and C 3-6 cycloalkyl; v is selected from 1 or 2;

[0298] o is selected from integers from 1 to 20, q is selected from integers from 1 to 20, and n is selected from integers from 0 to 12;

[0299] Or 2)R b Selected from orthogonal connectors "*" indicates the terminal connected to Lp, and A7 and A8 are the keys connected to -C(O)- respectively;

[0300] R c Selected from the bond or -BB-, where -BB- is selected from 1 to 5 peptide residues composed of amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, and aspartic acid.

[0301] R d Selected from hydrogen or C 1-6 alkyl;

[0302] R a Selected from hydrogen, C 1-6 Alkyl, C 1-6 Alkoxy and C 3-6 cycloalkyl;

[0303] v is selected from 1 or 2;

[0304] o is an integer from 1 to 20, q is an integer from 1 to 20, and n is an integer from 0 to 12.

[0305] In some embodiments, the hydrophilic unit U in the compound of formula IIIA or IIIa is Where o is an integer between 1 and 20, q is an integer between 1 and 20, and R a Selected from hydrogen, C 1-6 Alkyl, C 1-6 Alkoxy and C 3-6 Cycloalkyl, such as methyl.

[0306] In some embodiments, the compound represented by formula IA or Ia, or a pharmaceutically acceptable salt thereof, is represented by the following formula:

[0307] wherein each of p1, p2, p3is independently selected from 0, 1, 2, 3, and 4; r is selected from an integer from 1-6; X, D, and U are as defined in the compound of Formula IA or Formula la.

[0308] In some embodiments, the compound of Formula IA or la, or pharmaceutically acceptable salt thereof, is represented by the following formula:

[0309] wherein each of p2, p3, p4is independently selected from 0, 1, 2, 3, and 4; E is a leaving group, such as a halogen; r is selected from an integer from 1-6; X, D, and U are as defined in the compound of Formula IA or Formula la.

[0310] In some embodiments, U is wherein o is an integer from 1-20, q is an integer from 1-20, R a selected from C 1-6 alkyl, C 1-6 alkoxy, and C 3-6 cycloalkyl, for example methyl. In some embodiments, U is o is an integer from 4-8 (e.g., 5, 6, and 7), and p is an integer from 3-7 (e.g., 4, 5, and 6). In some embodiments, U is wherein o is 8, q is 6, R a is methyl. In some embodiments, U is wherein o is 8, q is 5, R a is methyl. In some embodiments, U is wherein o is 8, q is 4, R a is methyl. In some embodiments, U is wherein o is 8, q is 3, R a is methyl. In some embodiments, U is wherein o is 7, q is 6, R a is methyl. In some embodiments, U is wherein o is 7, q is 5, R a is methyl. In some embodiments, U is wherein o is 7, q is 4, R a is methyl. In some embodiments, U is wherein o is 7, q is 3, R a is methyl. In some embodiments, U is wherein o is 6, q is 6, R a is methyl. In some embodiments, U is wherein o is 6, q is 5, R a is methyl. In some embodiments, U is wherein o is 6, q is 4, R a is methyl. In some embodiments, U is wherein o is 6, q is 3, R a is methyl. In some embodiments, U is wherein o is 5, q is 6, R a is methyl. In some embodiments, U is wherein o is 5, q is 5, R a is methyl. In some embodiments, U is wherein o is 5, q is 4, R a is methyl. In some embodiments, U is wherein o is 5, q is 3, R a is methyl. In some embodiments, U is wherein o is 4, q is 5, R a is methyl. In some embodiments, U is wherein o is 4, q is 6, R a is methyl. In some embodiments, U is wherein o is 4, q is 7, R a is methyl. In some embodiments, U is wherein o is 4, q is 3, R a is methyl. In some embodiments, U is wherein o is 4, q is 2, R a is methyl.

[0311] In some embodiments, U is wherein o is an integer from 1 to 20, q is an integer from 1 to 20, R a is selected from C 1-6 alkyl, C 1-6 alkoxy, and C 3-6 cycloalkyl, for example methyl. In some embodiments, U is o is an integer from 4 to 8 (e.g., 5, 6, and 7), and p is an integer from 3 to 7 (e.g., 4, 5, and 6). In some embodiments, U is wherein o is 8, q is 6, R a is methyl. In some embodiments, U is where o is 8, q is 5, R a is methyl. In some embodiments, U is where o is 8, q is 4, R a is methyl. In some embodiments, U is where o is 8, q is 3, R a is methyl. In some embodiments, U is where o is 7, q is 6, R a is methyl. In some embodiments, U is where o is 7, q is 5, R a is methyl. In some embodiments, U is where o is 7, q is 4, R a is methyl. In some embodiments, U is where o is 7, q is 3, R a is methyl. In some embodiments, U is where o is 6, q is 6, R a is methyl. In some embodiments, U is where o is 6, q is 5, R a is methyl. In some embodiments, U is where o is 6, q is 4, R a is methyl. In some embodiments, U is where o is 6, q is 3, R a is methyl. In some embodiments, U is where o is 5, q is 6, R a is methyl. In some embodiments, U is where o is 5, q is 5, R a is methyl. In some embodiments, U is where o is 5, q is 4, R a is methyl. In some embodiments, U is where o is 5, q is 3, R a is methyl. In some embodiments, U is where o is 4, q is 5, R a is methyl. In some embodiments, U is where o is 4, q is 6, R a is methyl. In some embodiments, U is where o is 4, q is 7, R a is methyl. In some embodiments, U is where o is 4, q is 3, R amethyl. In some embodiments, U is wherein o is 4, q is 2, R a methyl. In some embodiments, U is wherein o is an integer from 1 to 20, q is an integer from 1 to 20, R a selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy, and C 3-6 cycloalkyl, for example methyl.

[0312] In some embodiments, the compound of Formula IA or la is selected from:

[0313] wherein each of p1, p2, p3 is independently selected from 0, 1, 2, 3, and 4; r is selected from an integer from 1 to 6; D is as defined in the compound of Formula IA or la; R 3 selected from hydrogen, C 3-6 cycloalkylalkyl, C 3-6 cycloalkyl, or 3-6 membered heterocycloalkyl; R 4 selected from hydrogen, haloalkyl, C 3-6 cycloalkyl, or 3-6 membered heterocycloalkyl, preferably hydrogen; or, R 3 and R 4 together with the carbon atom to which they are attached form a C3-6 cycloalkyl or 3-6 membered heterocycloalkyl.

[0314] In another aspect, in some embodiments, the compound of Formula IA or la is selected from:

[0315] wherein each of p1, p2, p3 is independently selected from 0, 1, 2, 3, and 4; r is selected from an integer from 1-6; U and D are as defined in the compound of Formula la.

[0316] In some embodiments, the compound of Formula IA or la is selected from:

[0317] wherein each of p2, p3, p4 is independently selected from 0, 1, 2, 3, and 4; r is selected from an integer from 1-6; E is a leaving group, such as a halogen; U and D are as defined in the compound of Formula la.

[0318] In other embodiments, the compound of Formula IA or la is selected from:

[0319] wherein each of p1, p2, p3 is independently selected from 0, 1, 2, 3, and 4; r is selected from an integer from 1-6; U and D are as defined in the compound of Formula IA or Formula la.

[0320] In some embodiments, the compound of Formula IA or la is selected from:

[0321] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from:

[0322] In some embodiments, the compound of Formula IA or la is selected from:

[0323] In some embodiments, the compound of Formula IA or la, or a pharmaceutically acceptable salt thereof, is selected from:

[0324] The present disclosure also provides the following compound or a pharmaceutically acceptable salt thereof, which is selected from:

[0325] The present disclosure also provides the following compound or a pharmaceutically acceptable salt thereof, which is selected from:

[0326] wherein, Ab is a polypeptide or an antibody; k is selected from 1-10, which can be an integer or a decimal; Z is selected from a unit covalently linked to Ab; L is a stretch unit; Sp is Lp-(X) b ; Lp is an amino acid unit; X is a spacer unit; b is selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10; D is a drug unit; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10; U is a hydrophilic unit, which comprises a polyethylene glycol structural unit and a polysarcosine structural unit.

[0327] In some embodiments, the ligand-drug conjugate of Formula IIA or a pharmaceutically acceptable salt thereof is one in which b = 1.

[0328] In some embodiments, the ligand-drug conjugate of Formula IIA or a pharmaceutically acceptable salt thereof is one of Formula IIa

[0329] wherein, Ab is a polypeptide or an antibody; k is selected from 1-10, which can be an integer or a decimal; Z is selected from a unit covalently linked to Ab; D is a drug unit; X is a spacer unit; Lp is an amino acid unit; U is a hydrophilic unit, which comprises a polyethylene glycol structural unit and a polysarcosine structural unit; L is a stretch unit; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0330] In some embodiments, the ligand-drug conjugate of Formula IIA or a pharmaceutically acceptable salt thereof is one in which b = 1.

[0331] In some embodiments, the ligand-drug conjugate of Formula IIA or a pharmaceutically acceptable salt thereof is one of Formula IIb

[0332] wherein, Ab is a polypeptide or an antibody; k is selected from 1-10, which can be an integer or a decimal; Z is selected from a unit covalently linked to Ab; D is a drug unit; Lp is an amino acid unit; U is a hydrophilic unit, which comprises a polyethylene glycol structural unit and a polysarcosine structural unit; L is a stretch unit; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0333] In some embodiments, the hydrophilic unit in the compound of Formula IIA or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, is -R b -[R e -(OCH2CH2) q -R c -R f- [C(O)CH2NCH3] o -R a ] v , -R b -[R e -(OCH2CH2) q -R c -R f -(OCH2CH2) q -R a ] v or -R b -[R e -[C(O)CH2NCH3] o -R c -R f- (OCH2CH2) q -R a ] v , v is selected from 1 or 2, o is an integer from 1 to 20, and q is an integer from 1 to 20;

[0334] wherein, 1) R b is selected from a bond or -AA-, -AA- is selected from 1 to 5 amino acid residues;

[0335] R e is selected from a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d -, or -NR d -C(O)-;

[0336] R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 amino acid residues of a peptide consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0337] R f is selected from the group consisting of a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0338] R d is selected from the group consisting of hydrogen or C 1-6 alkyl;

[0339] R a is selected from the group consisting of hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0340] or 2) R b is selected from the group consisting of a direct bond “*” is the bond to Sp, A7and A8are the bonds to R e , respectively;

[0341] R e is selected from the group consisting of a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -Calkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0342] R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 amino acid residues selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0343] R f is selected from the group consisting of a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0344] R d is selected from the group consisting of hydrogen or Ci-6alkyl;

[0345] R a is selected from the group consisting of hydrogen, Ci-6alkyl, Ci-6alkoxy and C 3-6 cycloalkyl;

[0346] R 12each independently selected from the group consisting of hydrogen, Ci-6alkyl, Ci-6alkoxy, and C 3-6 cycloalkyl.

[0347] In some embodiments, the hydrophilic unit in the compound of Formula II A or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, is -R b -[R e -(OCH2CH2) q -R c -R f- [C(O)CH2NCH3] o -R a ] v , -R b -[R e -(OCH2CH2) q -R c -R f -(OCH2CH2) q -R a ] v or -R b -[R e -[C(O)CH2NCH3] o -R c -R f- (OCH2CH2) q -R a ] v wherein R b , R e , R c , R f , q, o, v are as previously defined; R a is selected from hydrogen.

[0348] In some embodiments, R b is selected from -AA-, -AA- is selected from a peptide residue of 1 to 5 amino acid residues, including but not limited to phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, or derivatives thereof.

[0349] In some embodiments, R 12 each independently is selected from hydrogen.

[0350] In some embodiments, the hydrophilic unit in the compound of Formula II A or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, is -R b -[R e -(OCH2CH2) q -R c -R f- [C(O)CH2NCH3] o -R a] v -R b -[R e -(OCH2CH2) q -R c -R f -(OCH2CH2) q -R a ] v or -R b -[R e -[C(O)CH2NCH3] o -R c -R f -(OCH2CH2) q -R a ] v v is selected from 1 or 2;

[0351] Among them, 1)R b Selected from the bond or -AA-, where -AA- is selected from 1 to 5 peptide residues composed of amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, and aspartic acid.

[0352] R e Selected from key, C 1-12 Alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 Alkylene-NR d -、-C(O)-C 1-12 alkylene-, -C 1-12 Alkylene -C(O)-, -C 1-12 Alkylene-NR d -C(O)-、-C 1-12 Alkylene-C(O)-NR d -C(O)-、-C 1-12 Alkylene-NR d -C(O)-C 1-12 Alkylene-, -NR d -C 1-12 Alkylene -C(O)-, -C(O)-C 1-12 Alkylene-NR d -or-NR d -C(O)-;

[0353] R c Selected from the bond or -BB-, where -BB- is selected from 1 to 5 peptide residues composed of amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, and aspartic acid.

[0354] Rf selected from bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0355] R d selected from hydrogen or C 1-6 alkyl;

[0356] R a selected from C1-6alkyl, C1-6alkoxy and C 3-6 cycloalkyl;

[0357] or 2) R b selected from orthogonal linker “*” is the attachment point to Sp, A7and A8are the linking bonds to R e , respectively;

[0358] R e selected from bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NRd -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0359] R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of a peptide residue of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0360] R f is selected from the group consisting of a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0361] R d is selected from the group consisting of hydrogen or C 1-6 alkyl;

[0362] R a is selected from the group consisting of C1-6alkyl, C1-6alkoxy and C 3-6 cycloalkyl.

[0363] In some embodiments, the hydrophilic unit in the compound of Formula II A or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, is -R b -[R e -(OCH2CH2) q -R c -R f -[C(O)CH2NCH3] o -R a ] v , -Rb -[R e -(OCH2CH2) q -R c -R f -(OCH2CH2) q -R a ] v or-R b -[R e -[C(O)CH2NCH3] o -R c -R f -(OCH2CH2) q -R a ] v wherein R b , R e , R c , R f , q, o, v are as defined above; R a is selected from hydrogen.

[0364] In some embodiments, the ligand-drug conjugate of Formula II A or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, wherein the hydrophilic unit is

[0365] wherein,

[0366] 1) R b is selected from a bond or -AA-, R c is selected from a bond or -BB-, -AA- is selected from a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, -BB- is selected from a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0367] R d is selected from hydrogen or C 1-6 alkyl; R a is selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl; v is selected from 1 or 2;

[0368] o is selected from an integer of 1-20, q is selected from an integer of 1-20, n is selected from an integer of 0-12;

[0369] or 2) R b is selected from an orthogonal linker “*” is the connecting end with Lp, A7 and A8 are the connecting bonds with -C(O)-, respectively;

[0370] Rc is selected from the group consisting of a bond or -BB-, -BB- is selected from a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0371] R d is selected from the group consisting of hydrogen or C 1-6 alkyl;

[0372] R a is selected from the group consisting of hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0373] v is selected from 1 or 2;

[0374] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0375] In some embodiments, the Ligand-Drug Conjugate of Formula II A or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, wherein the hydrophilic unit is

[0376] wherein 1) R b is selected from the group consisting of a bond or -AA-, R c is selected from the group consisting of a bond or -BB-, -AA- is selected from a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, -BB- is selected from a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0377] R d is selected from the group consisting of hydrogen or C 1-6 alkyl;

[0378] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0379] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0380] or 2) R b is selected from the group consisting of an orthogonal linker “*” is the connecting end to Lp, A7 and A8 are the connecting bonds to -C(O)-, respectively;

[0381] R cis selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0382] R d is selected from the group consisting of hydrogen or C 1-6 alkyl;

[0383] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0384] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0385] In some embodiments, the hydrophilic unit in the compound of Formula II A or Formula IIa or Formula IIb or a pharmaceutically acceptable salt thereof is wherein R b , R e , R c , R f , q, o, v are as defined above; R a is selected from the group consisting of hydrogen.

[0386] In some embodiments, the hydrophilic unit in the compound of Formula II A or Formula IIa or Formula IIb or a pharmaceutically acceptable salt thereof is

[0387] wherein 1) R b is selected from the group consisting of a bond or -AA-, -AA- is selected from the group consisting of a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0388] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0389] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0390] or 2) R b is selected from the group consisting of an orthogonal linker “*” is the connecting end with Lp, A7 and A8 are the connecting bonds with -C(O)-, respectively;

[0391] R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 amino acid residues selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0392] R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl;

[0393] o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12.

[0394] In some embodiments, the hydrophilic unit in the compound of Formula II A or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, is wherein R b , R e , R c , R f , q, o, v are as defined above; R a is selected from the group consisting of hydrogen.

[0395] In some embodiments, the hydrophilic unit in the compound of Formula II A or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, is wherein o is an integer from 1 to 20; q is an integer from 1 to 20; R a is selected from the group consisting of C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl, for example methyl.

[0396] In some embodiments, the hydrophilic unit in the compound of Formula II A or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, is wherein R b , R e , R c , R f , q, o, v are as defined above; R a is selected from the group consisting of hydrogen.

[0397] In some embodiments, the hydrophilic unit in the compound of Formula II A or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, is is an integer from 4 to 8 (e.g., 5, 6 and 7), p is an integer from 3 to 7 (e.g., 4, 5 and 6).

[0398] In some embodiments, the hydrophilic unit in the compound of Formula II A or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, is wherein o is an integer from 1 to 20; q is an integer from 1 to 20; Ra selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl, for example methyl.

[0399] In some embodiments, the ligand-drug conjugate of Formula II A or Formula IIa or Formula IIb, or a pharmaceutically acceptable salt thereof, wherein the hydrophilic unit is o is an integer from 4 to 8 (e.g., 5, 6, and 7), and p is an integer from 3 to 7 (e.g., 4, 5, and 6).

[0400] In some embodiments, the ligand-drug conjugate of Formula II A or IIa, or a pharmaceutically acceptable salt thereof, wherein the amino acid unit further comprises -(CH2CH2O) n1 -C 1-2 alkylene-C(O)- or -[C(O)CH2NCH3] n2 wherein n1, n2 are integers from 1 to 10.

[0401] In some embodiments, the ligand-drug conjugate of Formula II A or IIa, or a pharmaceutically acceptable salt thereof, wherein 2 and L 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the end of L, A2is a bond to the end of X, and A3is a bond to the end of U.

[0402] In some embodiments, the ligand-drug conjugate of Formula II A or IIa, or a pharmaceutically acceptable salt thereof, wherein 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the end of L, A2is a bond to the end of X, and A3is a bond to the end of U.

[0403] In some embodiments, the ligand-drug conjugate of Formula II A or IIa, or a pharmaceutically acceptable salt thereof, wherein wherein B is 2 ​​​​​​​​comprises a peptide residue consisting of 1 to 5 amino acids selected from the group consisting of phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus.

[0404] In some embodiments, L 2 comprises a peptide residue consisting of valine and arginine.

[0405] In some embodiments, L 2 comprises a peptide residue consisting of alanine and alanine.

[0406] In some embodiments, L 2 comprises a peptide residue consisting of valine and lysine.

[0407] In some embodiments, L 2 is selected from valine-arginine (Val-Arg).

[0408] In some embodiments, L 2 is selected from valine-alanine (Val-Ala).

[0409] In some embodiments, L 2 is selected from alanine-alanine (Ala-Ala).

[0410] In some embodiments, L 2 is selected from valine-lysine (Val-Lys).

[0411] In some embodiments, L 2 is selected from glycine-glycine-phenylalanine-glycine (Gly-Gly-Phe-GLy).

[0412] In some embodiments, the ligand-drug conjugate of Formula II A or IIa, or a pharmaceutically acceptable salt thereof, L comprises / is selected from -R 8 -L 1 -, wherein R 8 is selected from -W1-C(O)-, -C(O)-W1-C(O)-, -W1-(CH2CH2O) p C(O)-, -W1-(CH2CH2O) p CH2C(O)-, -W1-(CH2CH2O) p CH2CH2C(O)-, -(CH2CH2O) p C(O)-, -(CH2CH2O) p CH2C(O)-, -(CH2CH2O) p CH2CH2C(O)-, wherein W1is selected from C1-8 alkylene, C6aryl, C 5-6 heteroaryl, C1-8alkylene-cycloalkyl, or a straight chain heteroalkylene of 1 to 8 atoms, which heteroalkylene contains 1 to 3 heteroatoms selected from N, O, or S, wherein said C1-8alkylene, C6aryl, C 5-6 heteroaryl, cycloalkyl, and straight chain heteroalkylene are each independently optionally further substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl, or C 1-6 alkoxy;

[0413] L 1 selected from -NR 9 (CH2CH2O) p CH2CH2C(O)-, -NR 9 (CH2CH2O) p CH2C(O)-, -S(CH2) p C(O)-, -(CH2) p C(O)-, or a bond;

[0414] wherein each p is independently selected from an integer from 1 to 20, and each R 9 is independently selected from a hydrogen atom and C 1-8 alkyl, said C 1- 8alkyl is optionally substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkoxy.

[0415] In some embodiments, the ligand-drug conjugate of Formula II A or I la, or a pharmaceutically acceptable salt thereof, is 8 selected from -C 1-6 alkylene-C(O)-, -(CH2-CH2O)2C(O)-, -(CH2-CH2O)2CH2C(O)-, -(CH2-CH2O)2CH2CH2C(O)-, -(CH2-CH2O)3C(O)-, and -(CH2-CH2O)4C(O)-.

[0416] In some embodiments, W1is selected from C6aryl or C 5-6 heteroaryl, said C6aryl or C 5-6 heteroaryl is each independently optionally further substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl, or C 1-6 alkoxy.

[0417] In some embodiments, the ligand-drug conjugate of Formula II A or I la, or a pharmaceutically acceptable salt thereof, is 8selected from -C1-8alkylene-cyclohexyl-C(O)-, -(CH2-CH2O)4CH2C(O)-, and -(CH2-CH2O)6CH2C(O)-.

[0418] In some embodiments, R in the ligand-drug conjugate of Formula II A or Ha is 8 selected from phenyl, which phenyl is optionally substituted with one or more halogen, C 1-6 alkyl.

[0419] In some embodiments, R in the ligand-drug conjugate of Formula II A or Ha is 8 selected from *end is connected to R; **end is connected to L 1 .

[0420] In some embodiments, L in the compound of Formula II A or Ha, or pharmaceutically acceptable salt thereof, comprises -R 8 -L 1 -, R 8 is selected from -W1-(CH2CH2O) p C(O)-, -W1-(CH2CH2O) p CH2C(O)-, -W1-(CH2CH2O) p CH2CH2C(O)-, W1is selected from C6aryl, C 5-6 heteroaryl, each of which C6aryl or C 5-6 heteroaryl is independently optionally further substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl, or C 1-6 alkoxy, L 1 is selected from a bond.

[0421] In some embodiments, R in the ligand-drug conjugate of Formula II A or Ha is 8 selected from p is selected from an integer between 1 and 20, e.g., 3 or 4; *end is connected to R; **end is connected to L1.

[0422] In some embodiments, R in the compound of Formula II A or Ha, or pharmaceutically acceptable salt thereof, is selected from 8 selected from p is selected from an integer between 1 and 20, e.g., 3 or 4; *end is connected to R; **end is connected to L1.

[0423] In some embodiments, L in the ligand-drug conjugate of Formula II A or Ha, or pharmaceutically acceptable salt thereof, is selected from -R 8 -L 1 -, R 8 , L1 as defined previously.

[0424] In another aspect, in some embodiments, L in the compound of Formula II A or IIa further comprises wherein each of h or j is independently selected from 0 or 1; R 104 is each independently selected from hydrogen or C 1-3 alkyl.

[0425] In some embodiments, L in the compound of Formula II A or IIa comprises

[0426] In some embodiments, L in the compound of Formula II A or IIa comprises

[0427] In some embodiments, L in the compound of Formula II A or IIa is selected from p3 is selected from 0, 1, 2, 3, and 4.

[0428] In some embodiments, a = 1 in the ligand-drug conjugate of Formula II A or IIa.

[0429] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is a ligand-drug conjugate of Formula II-1

[0430] In another aspect, the disclosure provides a ligand-drug conjugate or pharmaceutically acceptable salt thereof, wherein L 2 further comprises an orthogonal linker, allowing (U) to be in an orthogonal orientation relative to (X-D).

[0431] In some embodiments, the orthogonal linker is selected from:

[0432] t is 0, 1, 2, or 3, A4 is a bond to the B terminus, and A5 and A6 are bonds to the -X-D terminus.

[0433] In some embodiments, L in the ligand-drug conjugate or pharmaceutically acceptable salt thereof 2 comprises t is 0, 1, 2, or 3, A4 is a bond to the B terminus, and A5 and A6 are bonds to the -X-D terminus.

[0434] In some embodiments, L in the ligand-drug conjugate or pharmaceutically acceptable salt thereof 3 comprises t is 0, 1, 2, or 3, A4 is a bond to the B terminus, and A5 and A6 are bonds to the -X-D terminus.

[0435] In some embodiments, L 2 or L 3 comprises A4is a bond to the B terminus, A5and A6are bonds to the -X-D terminus.

[0436] In some embodiments, L 2 or L 3 comprises A4is a bond to the B terminus, A5and A6are bonds to the -X-D terminus.

[0437] In some embodiments, L 2 or L 3 comprises A4is a bond to the B terminus, A5and A6are bonds to the -X-D terminus.

[0438] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is a ligand-drug conjugate of Formula II-2 wherein Ab is a polypeptide or antibody; Z is selected from units covalently linked to Ab; L, U, X and D are as defined in the compound of Formula IIa; B is A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus; t is 0, 1, 2 or 3.

[0439] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is a ligand-drug conjugate of Formula II-3 wherein Ab is a polypeptide or antibody; Z is selected from units covalently linked to Ab; L, U, X and D are as defined in the compound of Formula IIa; B is A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus; t is 0, 1, 2 or 3.

[0440] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is a ligand-drug conjugate of Formula II-4 wherein Ab is a polypeptide or antibody; Z is selected from units covalently linked to Ab; L, U, X and D are as defined in the compound of Formula IIa; B is A1is a bond to the L terminus, A2, A7are bonds to the D terminus, A3is a bond to the U terminus; L 4comprises a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid.

[0441] In some embodiments, the orthogonal linker is selected from:

[0442] wherein each t1 is independently selected from 0, 1, 2, 3, or 4; each t2 is independently selected from 1, 2, 3, or 4; A4 is a bond to the B terminus, A5 and A6 are bonds to the -X-D terminus.

[0443] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is a ligand-drug conjugate of Formula II-5 wherein Z, L, U, X and D are as defined in Formula IIa; B is A1 is a bond to the L terminus, A2, A7 are bonds to the D terminus, A3 is a bond to the U terminus; t is 0, 1, 2, or 3; L 4 comprises a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid.

[0444] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is a ligand-drug conjugate of Formula II-6 wherein Z, L, U, X and D are as defined in Formula IIa; B is A1 is a bond to the L terminus, A2, A7 are bonds to the D terminus, A3 is a bond to the U terminus; t is 0, 1, 2, or 3; L 4 comprises a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid.

[0445] On the other hand, the method for coupling the linking group R to Ab in the compound of Formula II A or IIa or its pharmaceutically acceptable salt can be divided into two types, namely chemical method and enzymatic method. The chemical method is to connect the toxic drug and the antibody molecule through a specific chemical reaction (such as Michael reaction), which can accurately control the connection position and quantity, and ensure the stability and drug efficacy of the connection. The enzymatic method is to use a specific enzyme to mediate the connection to form a stable chemical bond between the toxic drug and the antibody.

[0446] In some embodiments, the reduced interchain disulfide bond is treated by a reducing agent such as tris (2-carboxyethyl) phosphine to generate cysteine, and then thiol-maleimide coupling is performed, as shown in the following example:

[0447] In some embodiments, an azido group (-N3) is introduced on Ab, the azido group click reacts with a triple bond linker to form the following structure: 1) 2) 3) wherein “*” represents the connecting end to Ab, and “**” represents the connecting end to L.

[0448] In the present disclosure, “the connecting end to Ab” means connecting to the functional group on one side of the antibody Ab or the antibody Ab containing, for example When coupled with the antibody Ab, its schematic structure is

[0449] In some embodiments, when the compound of formula IA or Ia containing the DBCO linker or a pharmaceutically acceptable salt thereof is coupled with the antibody, the antibody is treated by endosialidase (such as endos enzyme) to expose N-acetylglucosamine, and the N-acetylgalactosamine modified by azido is connected to the N-acetylglucosamine of the antibody by glycosyltransferase to obtain an azido-modified antibody, and the modified antibody is coupled with a triple bond linker to form an ADC by click reaction, which is represented as: “**” represents the connecting end to L.

[0450] The reaction conditions / operation steps of the click reaction in the present disclosure are described in CN111164208A, and the relevant contents are incorporated herein for illustration.

[0451] In other embodiments, The reaction conditions / operation steps of the class linker with Ab are described in WO2023216956A, and the relevant contents are incorporated herein for illustration.

[0452] In some embodiments, the ligand-drug conjugate of formula II A or IIa or a pharmaceutically acceptable salt thereof, Z is selected from the following group: optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted and optionally substituted wherein r is selected from an integer from 1 to 6, such as 3 and 4; "*" indicates the end connected to Ab.

[0453] In some embodiments, the ligand-drug conjugate of Formula II A or IIa, or a pharmaceutically acceptable salt thereof, is selected from "*" indicates the end connected to Ab.

[0454] The disclosure "*" or "**" indicates the end connected to other functional groups, for example when when connected to an antibody Ab, the schematic structure is

[0455] In another aspect, the disclosure also provides a ligand-drug conjugate of Formula IIB, or a pharmaceutically acceptable salt thereof

[0456] wherein Ab is a polypeptide or an antibody; k is selected from 1 to 10, which can be an integer or a decimal number; Z is selected from a unit covalently linked to Ab; D is a drug unit; X is a spacer unit; Lp is an amino acid unit; U is a hydrophilic unit comprising a polyethylene glycol structural unit and a polysarcosine structural unit; L is a stretch unit; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

[0457] In other embodiments, the ligand-drug conjugate of Formula II A, or a pharmaceutically acceptable salt thereof, is selected from a ligand-drug conjugate of Formula IVA-1 or IVA-2, or a pharmaceutically acceptable salt thereof

[0458] wherein Ab is a polypeptide or an antibody; k is selected from 1 to 10, which can be an integer or a decimal number; D is a drug unit; Sp is Lp-(X) b ; X is a spacer unit; Lp is an amino acid unit; U is a hydrophilic unit comprising a polyethylene glycol structural unit and a polysarcosine structural unit; L is a stretch unit; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and b is selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10;

[0459] R 8selected from -W1-C(O)-, -C(O)-W1-C(O)-, -W1-(CH2CH2O) p C(O)-, -W1-(CH2CH2O) p CH2C(O)-, -W1-(CH2CH2O) p CH2CH2C(O)-, -(CH2CH2O) p C(O)-, -(CH2CH2O) p CH2C(O)-, -(CH2CH2O) p CH2CH2C(O)-, wherein W1is selected from C 1-8 alkylene, C6aryl, C 5-6 heteroaryl, C 1-8 alkylene-cycloalkyl or straight chain heteroalkyl of 1 to 8 atoms, said heteroalkylene comprising 1 to 3 heteroatoms selected from N, O or S, wherein said C 1-8 alkylene, C6aryl, C 5-6 heteroaryl, C 1-8 alkylene-cycloalkyl and straight chain heteroalkylene are each independently optionally further substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy;

[0460] L 1 selected from -NR 9 (CH2CH2O) p CH2CH2C(O)-, -NR 9 (CH2CH2O) p CH2C(O)-, -S(CH2) p C(O)-, -(CH2) p C(O)- or a bond, preferably a bond;

[0461] wherein each p is independently selected from an integer from 1 to 20, R 9 are each independently selected from a hydrogen atom and a C 1-8 alkyl, said C 1- 8alkyl is optionally substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkoxy; E is each independently selected from a leaving group, such as halogen;

[0462] is a chemical bond or is absent.

[0463] In certain embodiments, the ligand-drug conjugate of Formula IVA-1 or IVA-2, or a pharmaceutically acceptable salt thereof, is prepared by the reaction as shown below:

[0464] In certain embodiments, the ligand-drug conjugate of Formula IVA-1 or IVA-2, or a pharmaceutically acceptable salt thereof, is prepared by the reaction as shown below: Note: The thiol group (-S) on antibody Ab is not shown in the structure of IVA-1 / IVA-2.

[0465] In some embodiments, the general method for site-directed conjugation comprises the following steps:

[0466] wherein the antibody is reduced to open the disulfide bond, then conjugated with the linker to form the bridged ligand-drug conjugate, and then hydrolyzed to open the maleimide ring to obtain the target product. The related method is referred to the method in WO2024251149, and the related content is incorporated herein by reference.

[0467] In some embodiments, the ligand-drug conjugate of Formula IVA-1 or IVA-2, or a pharmaceutically acceptable salt thereof, is a ligand-drug conjugate of Formula IVa-1 or IVa-2, or a pharmaceutically acceptable salt thereof wherein Ab, D, Lp, X, U, a, R 8 , L 1 , E, as defined in the compound of Formula IVA-1.

[0468] In some embodiments, the ligand-drug conjugate of Formula IVA-1 or IVA-2, or a pharmaceutically acceptable salt thereof, is a ligand-drug conjugate of Formula IVb-1 or IVb-2, or a pharmaceutically acceptable salt thereof wherein Ab, D, Lp, X, U, a, R8, L1, E, as defined in the compound of Formula IVA-1.

[0469] In some embodiments, the ligand-drug conjugate of Formula IVA-1 or IVA-2 is selected from:

[0470] In some embodiments, the ligand-drug conjugate of Formula IVA-1 or IVA-2, or a pharmaceutically acceptable salt thereof, is selected from a ligand-drug conjugate of Formula IVA-1a or IVA-2a, or a pharmaceutically acceptable salt thereof

[0471] wherein R 15 is selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy; z is selected from 0, 1, 2, 3 or 4; D, Sp, U, a are as defined in the compound of Formula IVA-1; each p4 is independently selected from 0, 1, 2, 3 and 4.

[0472] In some embodiments, the Ligand-Drug Conjugate of Formula IVA-1 or IVA-2, or a pharmaceutically acceptable salt thereof, is selected from the Ligand-Drug Conjugate of Formula IVA-1b or IVA-2b, or a pharmaceutically acceptable salt thereof

[0473] wherein R 15 selected from halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy; z is selected from 0, 1, 2, 3, or 4; D, Sp, U, a are defined as in the compound of Formula IVA-1; each p4 is independently selected from 0, 1, 2, 3, and 4.

[0474] In some embodiments, the use of hydrophilic groups and disubstituted maleimides, such as dibromomethyl amide (DBM) or dithienyl maleimides, can better achieve conjugation of the linker to the antibody in ADCs, resulting in more uniform and stable ADCs with a DAR of 4. In some embodiments, the Ligand-Drug Conjugate of Formula IVA-1 or IVA-2 has a DAR 4 content of 80% or more (e.g., 85%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%).

[0475] In some embodiments, the Ligand-Drug Conjugate of Formula IVA-1 or IVA-2 has a DAR 4 content of greater than 85%. In some embodiments, the Ligand-Drug Conjugate of Formula IVA-1 or IVA-2 has a DAR 4 content of greater than 86%. In some embodiments, the Ligand-Drug Conjugate of Formula IVA-1 or IVA-2 has a DAR 4 content of greater than 88%. In some embodiments, the Ligand-Drug Conjugate of Formula IVA-1 or IVA-2 has a DAR 4 content of greater than 90%. In some embodiments, the Ligand-Drug Conjugate of Formula IVA-1 or IVA-2 has a DAR 4 content of 85%. In some embodiments, the Ligand-Drug Conjugate of Formula IVA-1 or IVA-2 has a DAR 4 content of 90%. In some embodiments, the Ligand-Drug Conjugate of Formula IVA-1 or IVA-2 has a DAR 4 content of 95%. In some embodiments, the Ligand-Drug Conjugate of Formula IVA-1 or IVA-2 has a DAR 4 content of 100%.

[0476] In some embodiments, the Ligand-Drug Conjugate of Formula II A or IIa is selected from:

[0477] wherein each of p1, p2, p3, p4 is independently selected from 0, 1, 2, 3, and 4; k is selected from 1-10, which can be an integer or a decimal number; r is selected from an integer between 1-6; Ab is a polypeptide or an antibody; U, X, and D are defined as in the compound of Formula IIa.

[0478] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is selected from:

[0479] wherein each of p2, p3 is independently selected from 0, 1, 2, 3, and 4; k is selected from 1-10, which can be an integer or a decimal number; Ab is a polypeptide or an antibody; U, X, and D are defined as in the compound of Formula IIa.

[0480] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is selected from:

[0481] wherein each of p2, p3 is independently selected from 0, 1, 2, 3, and 4; k is selected from 1-10, which can be an integer or a decimal number; Ab is a polypeptide or an antibody; U and D are defined as in the compound of Formula IIa.

[0482] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is selected from:

[0483] wherein k is selected from 1-10, which can be an integer or a decimal number; Ab is a polypeptide or an antibody.

[0484] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is selected from:

[0485] wherein p3 is selected from 0, 1, 2, 3, and 4; Ab is a polypeptide or an antibody; k is selected from 1-10, which can be an integer or a decimal; U, X, and D are defined as in the compound of Formula Ila.

[0486] In some embodiments, the spacer unit X in the ligand-drug conjugate of Formula IIA or Ila comprises / or is selected from the following moieties: -(CR 1 R 2 ) m1 -O(CR 1 R 2 ) m2 -CR 3 R 4 -C(O)-, -(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -CR 3 R 4 -C(O)-, -(CR 1 R 2 ) m1 O-CR 3 R 4 (CR 1 R 2 ) m2 -, -(CR 1 R 2 ) m1 OCR 3 R 4 -C(O)-, -(CR 1 R 2 ) m1 -O-(CR 1 R 2 ) m2 C(O)-, -(CR 1 R 2 ) m1 -S-(CR 1 R 2 ) m2 -CR 3 R 4 -C(O)-, -(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -O-M-C(O)- and -(CR 1 R 2 ) m1 NH-(CR 1 R2 ) m2 -CR 3 R 4 -,

[0487] Where R 1 and R 2 They may be the same or different, and each is independently selected from hydrogen, deuterium, halogen or alkyl;

[0488] R 3 Selected from hydrogen, C 3-6 cycloalkylalkyl, C 3-6 Cycloalkyl or 3-6 membered heterocyclic alkyl; R 4 Selected from hydrogen, haloalkyl, C 3-6 Cycloalkyl or 3-6 membered heterocycloalkyl; or, R 3 and R 4 Together with the carbon atoms it is attached to, they form C 3-6 Cycloalkyl or 3-6 membered heterocyclic alkanes;

[0489] m1 and m2 are each independently selected from 0, 1, 2 or 3;

[0490] M is selected from C 3-6 Cycloalkyl or 3-6 membered heterocyclic alkyl groups.

[0491] In some embodiments, the spacer unit X in the ligand-drug conjugate of formula IIA or IIa or its pharmaceutically acceptable salt is selected from the group consisting of: -NHCH2-, -NH-(CH2)3-C(O)-, -NH-CH2-O-CH2-C(O)-, -NH-(CH2)2-O-CH2-C(O)-,

[0492] In some implementations, the ligand-drug conjugates represented by formula IIA or IIa are selected from:

[0493] Where p1, p2, and p3 are each independently selected from 0, 1, 2, 3, and 4; k is selected from 1 to 10, and can be an integer or a decimal; Ab is a polypeptide or antibody; U and D are defined as in the compound shown in formula IIa; R 3 R 4 As defined above.

[0494] In some implementations, the ligand-drug conjugates represented by formula IIA or IIa are selected from:

[0495] wherein each of p2, p3, p4 is independently selected from 0, 1, 2, 3, and 4; k is selected from 1-10, which can be an integer or a decimal number; Ab is a polypeptide or an antibody; U and D are defined as in the compound of Formula IIa; R 3 , R 4 as defined previously.

[0496] In some embodiments, the spacer unit X in the ligand-drug conjugate of Formula II A or IIa, or a pharmaceutically acceptable salt thereof, is selected from

[0497] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is selected from:

[0498] wherein each of p1, p2, p3 is independently selected from 0, 1, 2, 3, and 4; Ab is a polypeptide or an antibody; k is selected from 1-10, which can be an integer or a decimal number; r is selected from an integer between 1-6; U and D are defined as in the compound of Formula IIa.

[0499] In other embodiments, the spacer unit X in the ligand-drug conjugate of Formula II A or IIa, or a pharmaceutically acceptable salt thereof, is selected from p-aminobenzyloxy carbonyl

[0500] In other embodiments, the ligand-drug conjugate of Formula II A or IIa is selected from:

[0501] wherein each of p1, p2, p3 is independently selected from 0, 1, 2, 3, and 4; k is selected from 1-10, which can be an integer or a decimal number; r is selected from an integer between 1-6; Ab is a polypeptide or an antibody; U and D are defined as in the compound of Formula IIa.

[0502] In some embodiments, the ligand-drug conjugate of Formula II A or IIa is selected from:

[0503] wherein each of pi, p2, p3, p4 is independently selected from 0, 1, 2, 3, and 4; k is selected from 1-10, which can be an integer or a decimal number; r is selected from an integer between 1-6; Ab is a polypeptide or an antibody; U and D are defined as in the compound of Formula Ila.

[0504] In another aspect, the present disclosure provides that the drug unit D in the ligand-drug conjugate of Formula IIA or Formula IIa is selected from a cytotoxic compound, for example, eribulin or an analog thereof, triciribine or an analog thereof, auristatin E or an analog thereof, auristatin F or an analog thereof, camptothecin or an analog thereof, cabazitaxel or an analog thereof.

[0505] The present disclosure provides that the drug unit D in the compound of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, can also be selected from a glucocorticoid (for example, budesonide or a derivative thereof).

[0506] In some embodiments, the drug unit D in the compound of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, is

[0507] In some embodiments, the drug unit D in the compound of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, is

[0508] In some embodiments, the drug unit D in the ligand-drug conjugate of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the ligand-drug conjugate of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the ligand-drug conjugate of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the ligand-drug conjugate of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the ligand-drug conjugate of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, is a glucocorticoid, for example, In some embodiments, the drug unit D in the ligand-drug conjugate of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, is In some embodiments, the drug unit D in the compound of Formula IIA or Formula IIa, or a pharmaceutically acceptable salt thereof, is In some embodiments, the compound of Formula II A or Ila, or a pharmaceutically acceptable salt thereof, is In some embodiments, the ligand-drug conjugate of Formula II A or Ila, or a pharmaceutically acceptable salt thereof, is wherein o is an integer between 1 and 20, q is an integer between 1 and 20, R

[0509] In some embodiments, the ligand-drug conjugate of Formula II A or Ila is selected from:

[0510] wherein each of pi, p2, p3, p4 is independently selected from 0, 1, 2, 3, and 4; r is selected from an integer between 1 and 6; k is selected from an integer or a decimal number between 1 and 10; Ab is a polypeptide or an antibody; and U is wherein o is an integer between 1 and 20, q is an integer between 1 and 20, R a selected from C 1-6 alkyl, C 1-6 alkoxy, and C 3-6 cycloalkyl, for example methyl; and D is selected from

[0511] In some embodiments, the ligand-drug conjugate, or a pharmaceutically acceptable salt thereof, is selected from:

[0512] k is selected from an integer or a decimal number between 1 and 10; and Ab is a polypeptide or an antibody.

[0513] In some embodiments, the ligand-drug conjugate, or a pharmaceutically acceptable salt thereof, is selected from:

[0514] k is selected from an integer or a decimal number between 1 and 10; and Ab is a polypeptide or an antibody.

[0515] In some embodiments, the compound of Formula II A or Ila is selected from:

[0516] k is selected from an integer or a decimal number between 1 and 10; and Ab is a polypeptide or an antibody.

[0517] The present disclosure also provides the following compounds or pharmaceutically acceptable salts thereof, and ligand-drug conjugates or pharmaceutically acceptable salts thereof:

[0518] In another aspect, the antibody in the ligand-drug conjugate of Formula IIA or IIa, or a pharmaceutically acceptable salt thereof, is selected from a murine antibody, a chimeric antibody, a humanized antibody, and a fully human antibody.

[0519] In some embodiments, the antibody in the ligand-drug conjugate of Formula IIA or IIa, or a pharmaceutically acceptable salt thereof, is selected from an anti-HER2 (ErbB2) antibody, an anti-EGFR antibody, an anti-B7-H3 antibody, an anti-c-Met antibody, an anti-HER3 (ErbB3) antibody, an anti-HER4 (ErbB4) antibody, an anti-CD20 antibody, an anti-CD22 antibody, an anti-CD30 antibody, an anti-CD33 antibody, an anti-CD44 antibody, an anti-CD56 antibody, an anti-CD70 antibody, an anti-CD73 antibody, an anti-CD105 antibody, an anti-CEA antibody, an anti-A33 antibody, an anti-Cripto antibody, an anti-EphA2 antibody, an anti-G250 antibody, an anti-MUC1 antibody, an anti-Lewis Y antibody, an anti-VEGFR antibody, an anti-GPNMB antibody, an anti-Integrin antibody, an anti-PSMA antibody, an anti-Tenascin-C antibody, an anti-SLC44A4 antibody, an anti-CD79 antibody, an anti-TROP-2 antibody, an anti-CD79B antibody, an anti-Mesothelin antibody, and an anti-TF antibody.

[0520] In some embodiments, the antibody in the ligand-drug conjugate of Formula IIA or IIa, or a pharmaceutically acceptable salt thereof, is an anti-Claudin 18.2 antibody.

[0521] In some embodiments, the antibody in the ligand-drug conjugate of Formula IIA or IIa, or a pharmaceutically acceptable salt thereof, is a known antibody selected from, but not limited to, Trastuzumab, Pertuzumab, Nimotuzumab, Enoblituzumab, Emibetuzumab, Inotuzumab, Pinatuzumab, Brentuximab, Gemtuzumab, Bivatuzumab, Lorvotuzumab, cBR96, Rilotumumab, and Glematumamab.

[0522] In some embodiments, Ab in the ligand-drug conjugate of Formula II A or IIa is selected from a polypeptide. In some embodiments, the polypeptide has a length of less than 100 residues, such as less than 50 residues, less than 20 residues. Exemplary polypeptides are shown in CN1019541938, the relevant content of which is incorporated herein by reference.

[0523] In some embodiments, Ab in the ligand-drug conjugate of Formula II A or IIa is selected from trastuzumab or pertuzumab.

[0524] In some embodiments, Ab in the ligand-drug conjugate of Formula II A or IIa is selected from trastuzumab or pertuzumab.

[0525] The ligand-drug conjugate (LDC) described in the present disclosure is selected from:

[0526] wherein each of p1, p2, p3, p4 is independently selected from 0, 1, 2, 3 and 4; k is selected from 1-10, which can be an integer or a decimal number; r is selected from an integer between 1-6; U is wherein o is an integer between 1-20, q is an integer between 1-20, R a selected from C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl, for example methyl; and D is selected from

[0527] In another aspect, the present disclosure also provides a compound of Formula VA or a pharmaceutically acceptable salt thereof wherein D is a drug unit; Sp is Lp-(X) b ; X is a spacer unit; Lp is an amino acid unit; R 19 is a monovalent radical comprising a hydrophilic group; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, and b is selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10;

[0528] R 8 selected from -W1-C(O)-, -C(O)-W1-C(O)-, -W1-(CH2CH2O)pC(O)-, -W1-(CH2CH2O) pCH2C(O)-, -W1-(CH2CH2O) p CH2CH2C(O)-, -(CH2CH2O) p C(O)-, -(CH2CH2O) p CH2C(O)-, -(CH2CH2O) p CH2CH2C(O)-, wherein W1is selected from C 1-8 alkylene, C6aryl, C 5-6 heteroaryl, C 1-8 alkylene-cycloalkyl or straight chain heteroalkylene of 1 to 8 atoms, said heteroalkylene comprising 1 to 3 heteroatoms selected from N, O or S, wherein said C1-8alkylene, C6aryl, C 5-6 heteroaryl, C1-8alkylene-cycloalkyl and straight chain heteroalkylene are each independently optionally further substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy;

[0529] L 1 selected from -NR 9 (CH2CH2O) p CH2CH2C(O)-, -NR 9 (CH2CH2O) p CH2C(O)-, -S(CH2) p C(O)-, -(CH2) p C(O)- or a bond, preferably a bond;

[0530] wherein each p is independently selected from an integer from 1 to 20, R 9 each independently selected from a hydrogen atom and a C 1-8 alkyl group, said C 1- 8alkyl group is optionally substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkoxy; each E is independently selected from a leaving group, such as halogen;

[0531] is a chemical bond or is absent.

[0532] In some embodiments, the compound of formula VA or a pharmaceutically acceptable salt thereof is a compound of formula Va or a pharmaceutically acceptable salt thereof wherein D, Lp, X, R 19 , L, a, R 8 , L 1 , E, as defined in the compound of formula VA.

[0533] In some embodiments, the compound of Formula VA or a pharmaceutically acceptable salt thereof is a compound of Formula Vb or a pharmaceutically acceptable salt thereof wherein D, Lp, X, R 19 , L, a, R 8 , L 1 , E, as defined in the compound of Formula VA.

[0534] In some embodiments, E in the compound of Formula VA is selected from halogen or ArS-, Ar is selected from substituted or unsubstituted C 6- 10 , substituted or unsubstituted 5-12 membered heteroaryl.

[0535] In some embodiments, Ar in the compound of Formula VA is selected from phenyl, halobenzene, C 1-4 alkylphenyl, C 1-4 alkoxyphenyl, 2-pyridyl, 2-pyrimidinyl, 1-methylimidazol-2-yl or wherein R 13 , R 14 are each independently selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy, amino, C 3-6 cycloalkyl, C 3-6 heterocycloalkyl, said C 1-6 alkyl, C 1-6 alkoxy, amino, C 3-6 cycloalkyl, C 3-6 heterocycloalkyl are optionally further substituted with one or more substituents selected from halogen, hydroxy, cyano, nitro, oxo, amino, C 1-6 alkyl or C 1-6 alkoxy; or R 13 , R 14 form, together with the adjacent atom, a C 3- 6heterocycloalkyl, said C 3-6 heterocycloalkyl is optionally further substituted with one or more substituents selected from halogen, hydroxy, cyano, nitro, oxo, amino, C 1- 6alkyl or C 1-6 alkoxy.

[0536] In some embodiments, Ar in the compound of Formula VA is selected from R 13 , R 14 form, together with the adjacent atom, a C 3-6 heterocycloalkyl, said C 3-6 heterocycloalkyl is optionally further substituted with one or more substituents selected from halogen, hydroxy, cyano, nitro, oxo, amino, C 1-6 alkyl or C 1-6 alkoxy.

[0537] In some embodiments, the compound of Formula VA is a compound of Formula VA-1 or VA-2 R 13 , R 14 and the adjacent atoms form a pyrrolidinyl or piperidinyl group, which is optionally further substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, oxo, amino, C 1-6 alkyl or C 1-6 alkoxy.

[0538] In some embodiments, the compound of Formula VA is a compound of Formula VA-1 or VA-2

[0539] In some embodiments, the compound of Formula VA is a compound of Formula VA-1 or VA-2 5-6 In some embodiments, the compound of Formula VA is a compound of Formula VA-1 or VA-2 5- In some embodiments, the compound of Formula VA is a compound of Formula VA-1 or VA-2 1-6 In some embodiments, the compound of Formula VA is a compound of Formula VA-1 or VA-2 1-6 In some embodiments, the compound of Formula VA is a compound of Formula VA-1 or VA-2

[0540] In some embodiments, the compound of Formula VA is a compound of Formula VA-1 or VA-2

[0541] wherein R 13 , R 14 , R 15 , R 19 , z, D, Sp, U, a are as defined in the compound of Formula VA; each p4 is independently selected from 0, 1, 2, 3 and 4.

[0542] In some embodiments, the compound of Formula VA-1 or VA-2 is a compound of Formula VA-1A or VA-2A 13 , R 14 and the adjacent atoms form a pyrrolidinyl or piperidinyl group, which is optionally further substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, oxo, amino, C 1-6 alkyl or C 1-6 alkoxy; R 15 is selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy; z is selected from 0, 1, 2, 3 or 4; D, Sp, U, a are as defined in the compound of Formula VA.

[0543] In some embodiments, the compound of Formula VA-1 or VA-2 is a compound of Formula VA-1A or VA-2A 19one or more groups selected from carboxylic acid group, sulfonic acid group, phosphoric acid group, hydroxyl group, polyethylene glycol group, polysarcosine group, and sugar group.

[0544] In some embodiments, R 19 is selected from polyethylene glycol group, polysarcosine group, or a combination thereof.

[0545] In some embodiments, the compound of Formula VA is selected from:

[0546] wherein each p4 is independently selected from 0, 1, 2, 3, and 4.

[0547] In some embodiments, the compound of Formula VA or Formula Va is selected from:

[0548] wherein each p4 is independently selected from 0, 1, 2, 3, and 4; X, D, R 19 and a are as defined above.

[0549] In some embodiments, the amino acid unit in the compound of Formula VA or Formula Va comprises a peptide residue consisting of 2 to 7 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid. In some embodiments, the amino acid unit in the compound of Formula VA or Formula Va is defined the same as the amino acid unit in the compound of Formula IIIA or Ilia.

[0550] In some embodiments, D, X, a, R 8 , L 1 and E in the compound of Formula VA or Formula Va are defined the same as in the compound of Formula IIIA.

[0551] The compound of Formula VA or Va of the present disclosure can be conjugated with Ab to form a ligand-drug conjugate. In some embodiments, the ligand-drug conjugate is a ligand-drug conjugate of Formula VIA-1 or VIA-2 or a pharmaceutically acceptable salt thereof

[0552] wherein Ab is a polypeptide or an antibody; k is selected from 1-10, which can be an integer or a decimal number; D is a drug unit; Sp is Lp-(X) b ; X is a spacer unit; Lp is an amino acid unit; R 19 is a monovalent group comprising a hydrophilic group; L is a stretch unit; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and b is selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

[0553] R 8 selected from -W1-C(O)-, -C(O)-W1-C(O)-, -W1-(CH2CH2O) p C(O)-, -W1-(CH2CH2O) p CH2C(O)-, -W1-(CH2CH2O) p CH2CH2C(O)-, -(CH2CH2O) p C(O)-, -(CH2CH2O) p CH2C(O)-, -(CH2CH2O) p CH2CH2C(O)-, wherein W1is selected from C 1-8 alkylene, C6aryl, C 5-6 heteroaryl, C 1-8 alkylene-cycloalkyl or straight-chain heteroalkylene of 1 to 8 atoms, which heteroalkylene comprises 1 to 3 heteroatoms selected from N, O or S, wherein the C 1-8 alkylene, C6aryl, C 5-6 heteroaryl, C 1-8 alkylene-cycloalkyl and straight-chain heteroalkylene are each independently optionally further substituted by one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy;

[0554] L 1 selected from -NR 9 (CH2CH2O) p CH2CH2C(O)-, -NR 9 (CH2CH2O) p CH2C(O)-, -S(CH2)pC(O)-, -(CH2) p C(O)- or a bond, preferably a bond;

[0555] wherein, p each independently selected from an integer from 1 to 20, R 9 each independently selected from a hydrogen atom and C 1-8 alkyl, which C 1- 8alkyl is optionally substituted by one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkoxy; E is each independently selected from a leaving group, such as halogen;

[0556] is a chemical bond or is absent.

[0557] In some embodiments, the ligand-drug conjugate of Formula VIA-1 or VIA-2, or a pharmaceutically acceptable salt thereof, is a ligand-drug conjugate of Formula VIa-1 or VIa-2, or a pharmaceutically acceptable salt thereof wherein Ab, D, Lp, X, R 19 , a, R 8 , L 1 , E, are as defined in the compound of Formula VA-1.

[0558] In some embodiments, the ligand-drug conjugate of Formula VIA-1 or VIA-2, or a pharmaceutically acceptable salt thereof, is a ligand-drug conjugate of Formula VIb-1 or VIb-2, or a pharmaceutically acceptable salt thereof wherein Ab, D, Lp, X, R 19 , a, R 8 , L 1 , E, are as defined in the compound of Formula VA-1.

[0559] In some embodiments, the ligand-drug conjugate of Formula VIA-1 or VIA-2, or a pharmaceutically acceptable salt thereof, is selected from a ligand-drug conjugate of Formula VIA- la or VIA-2a, or a pharmaceutically acceptable salt thereof

[0560] wherein R 15 is selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy; z is selected from 0, 1, 2, 3 or 4; D, Sp, R 19 , a are as defined in the compound of Formula VIA-1; each p4 is independently selected from 0, 1, 2, 3 and 4.

[0561] In some embodiments, in the compound of Formula VIA-1 or VIA-2, R 19 is selected from one or more groups selected from carboxylic acid group, sulfonic acid group, phosphoric acid group, hydroxyl group, polyethylene glycol group, polyglutamic acid group and sugar group.

[0562] In some embodiments, in the compound of Formula VIA-1 or VIA-2, R 19 is selected from polyethylene glycol group, polyglutamic acid group or a combination thereof.

[0563] In some embodiments, the amino acid unit in the compound of Formula VIA-1 or VIA-2 comprises a peptide residue consisting of 2 to 7 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, and aspartic acid. In some embodiments, the amino acid unit in the compound of Formula VIA-1 or VIA-2 is defined as in the compound of Formula IVA-1 or Formula IVA-2.

[0564] In some embodiments, Ab, D, X, a, R 8 , L 1 , and E in the compound of Formula VIA-1 or VIA-2 are defined as in the compound of Formula IVA-1 or Formula IVA-2.

[0565] In some embodiments, the compound of Formula VA or Va is selected from the group consisting of:

[0566] wherein X and D are defined as in the compound of Formula IIIA or Ilia.

[0567] In some embodiments, the compound of Formula VA or Va is selected from the group consisting of:

[0568] In some embodiments, the compound of Formula VA or Va is selected from the group consisting of:

[0569] In other embodiments, the compound of Formula VIA-1 or VIA-2 is selected from the group consisting of:

[0570] wherein X and D are defined as in the compound of Formula IIIA or Ilia.

[0571] The present disclosure also provides isotopically-substituted versions of the aforementioned compounds or pharmaceutically acceptable salts thereof, ligand-drug conjugates. In some embodiments, the isotopically-substituted versions are deuterated versions.

[0572] The present disclosure also provides a pharmaceutical composition comprising the aforementioned ligand-drug conjugate or pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable excipient.

[0573] In certain embodiments, the pharmaceutical composition comprises 0.01-99.99% of the aforementioned ligand-drug conjugate or isotopically-substituted version thereof, based on the total weight of the composition.

[0574] In certain embodiments, the pharmaceutical composition contains 0.1-99.9% of the aforementioned ligand-drug conjugate, or a pharmaceutically acceptable salt thereof, or an isotopically-substituted variant thereof. In certain embodiments, the pharmaceutical composition contains 0.5%-99.5% of the aforementioned ligand-drug conjugate, or a pharmaceutically acceptable salt thereof, or an isotopically-substituted variant thereof. In certain embodiments, the pharmaceutical composition contains 1%-99% of the aforementioned ligand-drug conjugate, or a pharmaceutically acceptable salt thereof, or an isotopically-substituted variant thereof. In certain embodiments, the pharmaceutical composition contains 2%-98% of the aforementioned ligand-drug conjugate, or a pharmaceutically acceptable salt thereof, or an isotopically-substituted variant thereof.

[0575] In certain embodiments, the pharmaceutical composition contains 0.01%-99.9% of a pharmaceutically acceptable excipient, based on the total weight of the composition. In certain embodiments, the pharmaceutical composition contains 0.5%-99.5% of a pharmaceutically acceptable excipient. In certain embodiments, the pharmaceutical composition contains 1%-99% of a pharmaceutically acceptable excipient. In certain embodiments, the pharmaceutical composition contains 2%-98% of a pharmaceutically acceptable excipient.

[0576] The present disclosure also provides use of the aforementioned ligand-drug conjugate, or a pharmaceutically acceptable salt thereof, or the aforementioned pharmaceutical composition, in the manufacture of a medicament for treating or preventing a tumor.

[0577] In some embodiments, the tumor is a cancer associated with HER2, HER3, B7H3, or EGFR expression.

[0578] The present disclosure also provides use of the aforementioned ligand-drug conjugate, or a pharmaceutically acceptable salt thereof, or the aforementioned pharmaceutical composition, in the manufacture of a medicament for treating and / or preventing a cancer. In some embodiments, the cancer is selected from the group consisting of breast cancer, ovarian cancer, cervical cancer, uterine cancer, prostate cancer, kidney cancer, liver cancer, stomach cancer, thyroid cancer, pancreatic cancer, and lymphoma.

[0579] The present disclosure also provides a method of treating or preventing a tumor, comprising administering to a patient in need thereof a therapeutically effective amount of the aforementioned antibody-drug conjugate, or a pharmaceutically acceptable salt thereof, or the aforementioned pharmaceutical composition, wherein the tumor is a cancer associated with HER2, HER3, B7H3, or EGFR expression.

[0580] The present disclosure also provides a method of treating and / or preventing a cancer, comprising administering to a patient in need thereof a therapeutically effective amount of the aforementioned antibody-drug conjugate, or a pharmaceutically acceptable salt thereof, or the aforementioned pharmaceutical composition, wherein the cancer is selected from the group consisting of, but not limited to, breast cancer, ovarian cancer, cervical cancer, uterine cancer, prostate cancer, kidney cancer, liver cancer, stomach cancer, thyroid cancer, pancreatic cancer, and lymphoma.

[0581] The present disclosure further provides the aforementioned antibody-drug conjugate or a pharmaceutically acceptable salt thereof, or the aforementioned pharmaceutical composition for use in treating or preventing a tumor, wherein the tumor is a cancer associated with HER2, HER3, B7H3, EGFR, TF or Claudin 18.2 expression.

[0582] The present disclosure further provides the aforementioned antibody-drug conjugate or a pharmaceutically acceptable salt thereof, or the aforementioned pharmaceutical composition for use in treating and and / or preventing a cancer selected from, but not limited to, breast cancer, ovarian cancer, cervical cancer, uterine cancer, prostate cancer, kidney cancer, liver cancer, gastric cancer, thyroid cancer, pancreatic cancer and lymphoma.

[0583] The present disclosure further provides a kit comprising the ligand-drug conjugate or a pharmaceutically acceptable salt thereof, or the pharmaceutical composition described in the present disclosure.

[0584] In another aspect, the present disclosure also provides a compound represented by ploy A-1 or ploy A-2 or ploy A-3 or a salt thereof

[0585] R B -R b -[R e -(OCH2CH2) q -R c -R f -[C(O)CH2NCH3] o -R A ] v ploy A-1;

[0586] R B -R b -[R e -(OCH2CH2) q -R c -R f -(OCH2CH2) q -R A ] v ploy A-2;

[0587] R B -R b -[R e -[C(O)CH2NCH3] o -R c -R f- (OCH2CH2) q -R A ] v ployA-3;

[0588] wherein v is selected from 1 or 2, o is an integer from 1 to 20, and q is an integer from 1 to 20.

[0589] 1) R b is selected from the group consisting of a bond or -AA-, -AA- is selected from the group consisting of a peptide residue of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0590] R e is selected from the group consisting of a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, 1-12 -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C d alkylene-NR 1-12 -C(O)-, -C d alkylene-C(O)-NR 1-12 -C(O)-, -C d alkylene-NR 1-12 -C(O)-C d alkylene-, -NR 1-12 -C 1-12 alkylene-C(O)-, -C(O)-C d alkylene-NR d - or -NR c -C(O)-;

[0591] R f is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of a peptide residue of 1 to 5 amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0592] R 1-12 is selected from the group consisting of a bond, C d alkylene, -C(O)-, -NR 1-12 -C 1-12 alkylene-, -C d alkylene-NR 1-12 -, 1-12 -C(O)-C 1-12 alkylene-, -C d alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NRd -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0593] R d selected from hydrogen or C 1-6 alkyl;

[0594] ;

[0595] or 2) R b selected from ortho linker " " is the connecting end with Lp, A7 and A8 are the connecting bonds with R e ;

[0596] R e selected from bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0597] R c selected from bond or -BB-, -BB- is selected from a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid;

[0598] R f selected from bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-;

[0599] R d is selected from hydrogen or C 1-6 alkyl;

[0600] R A and R B are different and R A and R B one of R A and R B the other is a functionalization reactive group that is reactive toward covalently binding the bondable group under reaction conditions in which the inert group is non-reactive.

[0601] In some embodiments, the compound of ploy A-1 is a compound of ploy A-1a

[0602] wherein n is an integer from 1 to 20; R A , R B , R b , R c , R d , q, o are as defined in the compound of ploy A-1.

[0603] In some embodiments, the compound of ploy A-3 or a salt thereof is a compound of ploy A-3a wherein n is an integer from 1 to 20; R A , R B , R b , R c , R d , q, o are as defined in the compound of ploy A-3.

[0604] In some embodiments, the compound of formula ploy A-1 or ploy A-1a is a compound of formula ploy A-1aa wherein R A , R B , q, o are as defined in the compound of formula ploy A-1. In some embodiments, the compound of formula ploy A-3 or ploy A-3a is a compound of formula ploy A-3aa wherein R A , R B , q, o are as defined in the compound of formula ploy A-1.

[0605] In some embodiments, R A is selected from inert groups (e.g., C 1-6 alkyl, C 1-6 alkoxy, and C 3-6 cycloalkyl), and R B is selected from functional reactive groups (e.g., hydrogen, hydroxyl).

[0606] In some embodiments, R A is selected from hydrogen, C 1- 6alkyl, C 1-6 alkoxy, and C 3-6 cycloalkyl.

[0607] In some embodiments, R B is selected from hydrogen, hydroxyl. In some embodiments, R A is selected from inert groups (e.g., C 1-6 alkyl, C 1-6 alkoxy, and C 3-6 cycloalkyl), and R B is selected from functional reactive groups (e.g., hydrogen, hydroxyl).

[0608] In some embodiments, R A is selected from hydrogen, C 1-6 6alkyl, C 1-6 alkoxy, and C 3-6 cycloalkyl.

[0609] In some embodiments, RB selected from hydrogen, hydroxyl.

[0610] In some embodiments, R in the compound of Formula (A-1aa) or (A-3aa) or salts thereof is selected from the group consisting of hydrogen, C A selected from inert groups (e.g., C 1-6 alkyl, C 1-6 alkoxy, and C 3-6 cycloalkyl), R B selected from functional reactive groups (e.g., hydrogen, hydroxyl).

[0611] In some embodiments, R in the compound of Formula (A-1aa) or (A-3aa) or salts thereof is selected from the group consisting of hydrogen, C A selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy, and C 3-6 cycloalkyl.

[0612] In some embodiments, o + q in the compound of Formula (A-1) or (A-2) or (A-3) or salts thereof has a value of 8 to 13. In some embodiments, o + q in the compound of Formula (A-1) or (A-2) or (A-3) or salts thereof has a value of 12. In some embodiments, o + q in the compound of Formula (A-1) or (A-2) or (A-3) or salts thereof has a value of 11. In some embodiments, o + q in the compound of Formula (A-1) or (A-2) or (A-3) or salts thereof has a value of 10.

[0613] In some embodiments, o in the compound of Formula (A-1) or (A-2) or (A-3) or salts thereof is an integer from 4 to 8 (e.g., 5, 6, and 7), and q is an integer from 3 to 7 (e.g., 4, 5, and 6).

[0614] In some embodiments, R in the compound of Formula (A-1aa) or (A-3aa) or salts thereof is selected from the group consisting of hydrogen, C B selected from hydrogen, hydroxyl.

[0615] In some embodiments, o in the compound of Formula (A-1) or (A-2) or (A-3) or salts thereof is 8, and q is 6.

[0616] In some embodiments, o in the compound of Formula (A-1) or (A-2) or (A-3) or salts thereof is 8, and q is 5.

[0617] In some embodiments, o in the compound of Formula (A-1) or (A-2) or (A-3) or salts thereof is 8, and q is 5.

[0618] In some embodiments, the compound of ploy A-1 or ploy A-2 or ploy A-3 or a salt thereof, o is 6, q is 6.

[0619] In some embodiments, the compound of ploy A-3 is selected from

[0620] In some embodiments, the compound of ploy A-1 is selected from

[0621] The present disclosure also provides a compound of Formula IA or a pharmaceutically acceptable salt thereof wherein, D is a drug unit; Sp is Lp-(X) b ; X is a spacer unit; Lp is an amino acid unit; L is a stretch unit; R is a linker; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, b is selected from 0 or 1; U is generated by covalently binding ploy A-1 or ploy A-2 or ploy A-3 to Sp.

[0622] In another aspect, the present disclosure provides a method of preparing Formula IIIA-1, comprising the step of reacting a compound of Formula IIIA-1A with a compound of Formula IIIA-1B to form Formula IIIA-1,

[0623] wherein PG6 is selected from halogen, hydroxyl or alkyloxy (such as methoxy or ethoxy); R 13 , R 14 , R 15 , D, Sp, U, P4, z, a are defined in the compound of Formula IIIA-1.

[0624] In some embodiments, the method of preparing Formula IIIA-2, comprising the step of reacting a compound of Formula IIIA-2A with a compound of Formula IIIA-1B to form Formula IIIA-1,

[0625] wherein PG6 is selected from halogen, hydroxyl or alkyloxy (such as methoxy or ethoxy); R 13 , R 14 , R 15 , D, Sp, U, P4, z, a are defined in the compound of Formula IIIA-1.

[0626] In other embodiments, the compound of Formula IIIA-1A or IIIA-2A is reacted with Formula IIIA-1B in the presence of a condensing reagent. Condensing reagents include, but are not limited to, 2-(7-azabenzotriazolyl)-N,N,N',N'-tetramethyluronium hexafluorophosphate (HATU).

[0627] The present disclosure also provides the following compounds, or pharmaceutically acceptable salts thereof, which include:

[0628] wherein PG6is selected from halo, hydroxyl, or alkyloxy (such as methoxy or ethoxy); R 13 , R 14 , R 15 , D, Sp, U, P4, z, a are defined in the compound of Formula IIIA-1.

[0629] In some embodiments, the compound of Formula IIIA-1A is selected from:

[0630] In some embodiments, the compound of Formula IIIA-2A is selected from:

[0631] In another aspect, the present disclosure provides a method of preparing a compound of Formula IIIA-1, comprising the step of reacting a compound of Formula IIIA-1C,

[0632] wherein R 13 , R 14 , R 15 , D, Sp, U, P4, z, a are defined in the compound of Formula IIIA-1.

[0633] In some embodiments, the method of preparing a compound of Formula IIIA-2, comprising the step of reacting a compound of Formula IIIA-2C,

[0634] wherein R 13 , R 14 , R 15 , D, Sp, U, P4, z, a are defined in the compound of Formula IIIA-1.

[0635] In another aspect, the present disclosure also provides a compound of Formula IIIA-1C or IIIA-2C

[0636] wherein R 13 , R14 pyrrolidinyl or piperidinyl group, which pyrrolidinyl or piperidinyl group is optionally further substituted with one or more substituents selected from halogen, hydroxy, cyano, nitro, oxo, amino, C 1-6 alkyl or C 1-6 alkoxy; z is selected from 0, 1, 2, 3 or 4; D, Sp, U, a are defined as in the compound of formula IIIA. 15 halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy; z is selected from 0, 1, 2, 3 or 4; D, Sp, U, a are defined as in the compound of formula IIIA.

[0637] In some embodiments, the compound of formula IIIA-1C or IIIA-2C is conjugated to a ligand (e.g., an antibody) to form a ligand-drug conjugate.

[0638] In another aspect, the pyrimidine-based linker (comprising the structure shown below) is different from the traditional maleimide linker, but instead employs a methanesulfonylpyrimidine linker that couples to the thiol generated upon disulfide bond cleavage, a design that avoids the reversible Michael addition reaction typically associated with maleimide linkers, resulting in a more stable linker.

[0639] wherein r is selected from an integer from 1-6.

[0640] In some embodiments, the structure of mid-1 is the structure of mid-1a

[0641] In some embodiments, the structure of mid-2 is the structure of mid-2a

[0642] The present disclosure also provides methods of making the pyrimidine-based linker and intermediates of the schemes thereof, which are generally outlined below:

[0643] Scheme 1:

[0644]

[0645] wherein PG1is selected from hydrogen or a carboxyl protecting group (e.g., t-butyl), PG2is selected from hydrogen or a carboxyl protecting group (e.g., a succinimidyl group), PG3is selected from a halogen (e.g., chlorine or fluorine) or a methylthioether group (-SCH3), X is selected from a halogen (e.g., bromine), and p1is selected from 0, 1, 2, 3, and 4.

[0646] Scheme 2:

[0647] wherein PG1is selected from hydrogen or a carboxyl protecting group (e.g., t-butyl), PG2is selected from hydrogen or a carboxyl protecting group (e.g., succinimidyl), PG3is selected from a halogen (e.g., chloro) or a methyl sulfide group (-SCH3), X is selected from a halogen (e.g., bromo), and p3is selected from 0, 1, 2, 3, and 4.

[0648] Scheme 3:

[0649] wherein PG2is selected from hydrogen or a carboxyl protecting group (e.g., succinimidyl), PG3is selected from a halogen (e.g., chloro) or a methyl sulfide group (-SCH3), X is selected from a halogen (e.g., bromo), PG4is selected from hydrogen or an amino protecting group (e.g., benzyloxycarbonyl (Cbz)), and PG5is selected from hydrogen or a carboxyl protecting group (e.g., t-butyl).

[0650] In some embodiments, the compound of Formula mid-la-la is prepared by the method comprising the step of reacting a compound of Formula mid-la-la-c

[0651] In some embodiments, the compound of Formula mid-la-la is prepared by the method comprising the step of reacting a compound of Formula mid-la-la-c

[0652] wherein PG1is selected from hydrogen or a carboxyl protecting group (e.g., t-butyl), PG3is selected from a halogen (e.g., chloro) or a methyl sulfide group (-SCH3), and X is a halogen (bromo). In some embodiments, the compound of Formula mid-la-la-c is coupled with the compound of Formula mid-la-la-d in the presence of a metal catalyst, including but not limited to Pd, Cu, or a combination thereof. In some embodiments, the metal catalyst is selected from dichlorobis(triphenylphosphine)palladium / cuprous iodide.

[0653] In some embodiments, the compound of Formula mid-la-la is prepared by the method further comprising the step of converting the compound of Formula mid-la-la-e to a mesylpyrimidine compound and a deprotecting agent (PG1),

[0654] wherein PG1is selected from hydrogen or a carboxyl protecting group (e.g., t-butyl), and PG3is selected from a halogen (e.g., chloro) or a methyl sulfide group (-SCH3).

[0655] In some embodiments, the compound of Formula mid-la-la is prepared by the method comprising the steps of:

[0656] wherein PG1is selected from hydrogen or a carboxyl protecting group (e.g., t-butyl), PG2is selected from hydrogen or a carboxyl protecting group (e.g., succinimidyl), PG3is selected from a halogen (e.g., chloro) or a methyl sulfide group (-SCH3), and X is a halogen (bromo).

[0657] In some embodiments, the method of making a compound of Formula mid-la-la comprises the steps of:

[0658] wherein,

[0659] X is a halogen (bromo).

[0660] In some embodiments, the compound of Formula mid-la-2 is a compound of Formula mid-la-2a

[0661] In some embodiments, the method of making a compound of Formula mid-la-2a comprises the steps of:

[0662] wherein PG1is selected from hydrogen or a carboxyl protecting group (e.g., t-butyl), PG2is selected from hydrogen or a carboxyl protecting group (e.g., succinimidyl), PG3is selected from a halogen (e.g., chloro) or a methyl sulfide group (-SCH3).

[0663] In some embodiments, the reaction conditions of step a include, but are not limited to, a condensing reagent / base, such as 2-(7-azabenzotriazol)-N,N,N',N'-tetramethyluronium hexafluorophosphate / diisopropylamine.

[0664] In some embodiments, the reaction conditions of step b include, but are not limited to, a metal palladium, such as Pd(PPh3)2Cl2.

[0665] In some embodiments, step c further comprises a step of removing the carboxyl protecting group and / or oxidizing the sulfide to a sulfoxide. In some embodiments, removal of the carboxyl protecting group is described in the literature (Protective Groups in Organic Synthesis, 5thEd. T. W. Greene & P. G. M. Wuts) and includes, but is not limited to, basic conditions. In some embodiments, the reaction conditions for oxidizing the sulfide to a sulfoxide include, but are not limited to, m-CPBA (meta-chloroperoxybenzoic acid). Th

[0666] The present disclosure also provides a compound selected from:

[0667] ​wherein PG1is selected from hydrogen or a carboxyl protecting group (e.g., t-butyl), PG2is selected from hydrogen or a carboxyl protecting group (e.g., a succinimidyl group), PG3is selected from a halogen (e.g., chlorine or fluorine) or a methyl sulfide group (-SCH3), pi is selected from 0, 1, 2, 3, and 4, and PG4is selected from hydrogen or an amino protecting group (e.g., a benzyloxycarbonyl (Cbz) group). Pharmaceutically acceptable salts of the compounds described in the disclosure can be selected from inorganic or organic salts.

[0668] The active compounds can be prepared in a form suitable for administration in any appropriate way, preferably in unit dosage form, or in a form suitable for self-administration by a patient in a single dose. The unit dosage form of the compounds or compositions of the disclosure can be in the form of a tablet, capsule, cachet, vial, powder, granule, lozenge, suppository, reconstitutable powder, or liquid preparation.

[0669] The compounds of the disclosure can exist in particular geometric or stereoisomeric forms. The disclosure contemplates all such compounds, including cis- and trans-forms, (-)- and (+)-enantiomers, (R)- and (S)-enantiomers, diastereomers, (D)- isomers, (L)-isomers, as well as the racemic mixtures and other mixtures thereof, such as those that are enantiomeric or diastereomeric mixtures. Additional asymmetric carbon atoms can be present in a substituent group. All such isomers, as well as mixtures thereof, are included within the scope of the disclosure. The compounds of the disclosure containing an asymmetric carbon atom can be isolated in optically active form or as a racemic mixture. Optical isomers can be prepared from optically active starting materials or by resolution of a racemic mixture.

[0670] Optically active (R)- and (S)-isomers and D and L isomers can be prepared by chiral synthesis or by chiral reagents or other conventional techniques. If desired, one enantiomer of a compound of the disclosure can be obtained by asymmetric synthesis or derivatization with a chiral auxiliary, separation of the resulting diastereomeric mixture, and cleavage of the auxiliary to provide the pure desired enantiomer. Alternatively, when a basic functional group (e.g., an amino group) or an acidic functional group (e.g., a carboxyl group) is present in the molecule, diastereomeric salts can be formed with an appropriate optically active acid or base, and the diastereomeric salt separated by conventional means, and the desired enantiomer recovered by treating with base or acid, as appropriate. In addition, separation of the enantiomers and diastereomers is often accomplished by chromatography using a chiral stationary phase, optionally in combination with chemical derivatization (e.g., formation of a carbamate from an amine).

[0671] In the chemical structures of the compounds of the disclosure, the bond indicates that the configuration is not specified, i.e., if chiral isomers are present in the chemical structure, the bond may be or both configurations. For example include include

[0672] The compounds and intermediates of the present disclosure can also exist in different tautomeric forms, and all such forms are embraced within the scope of the present disclosure. The term "tautomer" or "tautomeric forms" refers to different energy structures that are interconvertible via a low energy barrier. For example, prototropic tautomers (also known as proton transfer tautomers) include interconversions via proton migration, such as keto-enol and imine-enamine, lactam-lactim isomerization. An example of a lactam-lactim equilibrium is between A and B as shown below.

[0673] All compounds in the present disclosure can be drawn as either Form A or Form B. All tautomeric forms are within the scope of the present disclosure. The naming of the compounds does not exclude any tautomer.

[0674] The present disclosure also includes some isotopically-labeled compounds of the present disclosure which are identical to those recited herein, but for the fact that one or more atoms are replaced by an atom having an atomic mass or mass number different from the atomic mass or mass number usually found in nature. Examples of isotopes that can be incorporated into compounds of the disclosure include isotopes of hydrogen, carbon, nitrogen, oxygen, phosphorous, sulfur, fluorine, iodine, and chlorine, such as 2 H, 3 H, 11 C, 13 C, 14 C, 13 N, 15 N, 15 O, 17 O, 18 O, 31 P, 32 P, 35 S, 18 F, 123 I, 125 I, and 36 Cl, and the like.

[0675] Unless otherwise indicated, when a position is designated specifically as deuterium (D), the position is understood to have deuterium in an abundance of at least 1000 times greater than the natural abundance of deuterium, which is 0.015% (i.e., at least 10% deuterium incorporation). Exemplary compounds having deuterium in an abundance of at least 1000 times greater than the natural abundance of deuterium, at least 2000 times greater than the natural abundance of deuterium, at least 3000 times greater than the natural abundance of deuterium, at least 4000 times greater than the natural abundance of deuterium, at least 5000 times greater than the natural abundance of deuterium, at least 6000 times greater than the natural abundance of deuterium, or greater. The present disclosure also includes various deuterated forms of the compounds of Formula (I). Each available hydrogen atom attached to a carbon atom can be independently replaced with a deuterium atom. One skilled in the art would be able to synthesize deuterated forms of the compounds of Formula (I) by reference to the relevant literature. Commercially available deuterated starting materials can be used in the preparation of deuterated forms of the compounds of Formula (I), or they can be synthesized using conventional techniques employing deuterated reagents, including but not limited to deuterated borane, tritiated borane tetrahydrofuran solution, deuterated lithium aluminum hydride, deuterated iodoethane, and deuterated iodomethane, among others.

[0676] The term

[0677] "Optionally" or "optional" means that the subsequently described event or circumstance can or can not occur, and the description includes instances where the event or circumstance occurs and instances where it does not. For example, "optionally substituted with halo or cyano" means that the alkyl group can or can not be substituted with halo or cyano, and the description includes instances where the alkyl group is substituted with halo or cyano and instances where the alkyl group is not substituted with halo or cyano. 1-6 "Alkyl" means that halo or cyano can or can not be present, and the description includes instances where the alkyl group is substituted with halo or cyano and instances where the alkyl group is not substituted with halo or cyano.

[0678] "Pharmaceutical composition" means a mixture of one or more of the compounds described herein, or physiologically acceptable salts or prodrugs thereof, with other chemical components, such as physiologically acceptable carriers and excipients. The purpose of a pharmaceutical composition is to facilitate administration of the active ingredient to an organism.

[0679] "Pharmaceutically acceptable excipient" includes any of the agents, carriers, glidants, sweetening agents, diluents, preservatives, dyes / colorants, flavoring agents, surface-active agents, wetting agents, dispersing agents, suspending agents, stabilizers, isotonic agents, solvents, or emulsifying agents, which have been approved by the United States Food and Drug Administration (FDA) as being acceptable for use in humans or domestic animals.

[0680] An "effective amount" or "therapeutically effective amount" as described herein includes an amount sufficient to ameliorate or prevent symptoms or conditions of a medical disorder. An effective amount also means an amount that is sufficient to allow or promote diagnosis. The effective amount for a particular patient or veterinary subject can vary depending on factors such as the condition to be treated, the overall health status of the patient, the method route and dosage of administration, and the severity of side effects. The effective amount can be the maximum dose or administration regimen that avoids significant side effects or toxic effects.

[0681] The term "stretching unit" refers to a chemical moiety that is covalently linked at one end to a ligand via a carbon atom and at the other end to an amino acid unit, a disulfide moiety, a sulfonamide moiety, or a non-peptidic chemical moiety.

[0682] The term "spacer unit" is a bifunctional chemical moiety that can be used to couple an amino acid unit and a cytotoxic drug to ultimately form an antibody-drug conjugate.

[0683] The term "amino acid" refers to an organic compound that contains an amino group and a carboxyl group in its molecular structure, and both the amino group and the carboxyl group are directly attached to a -CH- structure. The general formula is H2NCHRCOOH, where R is H, substituted or unsubstituted alkyl, etc. Depending on the position of the amino group attached to the carbon atom in the carboxylic acid, it can be classified as an a-, b-, y-, d-, e-...-amino acid. In the biological world, the amino acids that constitute natural proteins have their specific structural characteristics, i.e., their amino groups are directly attached to the a-carbon atom, i.e., a-amino acids, including glycine (Glycine), alanine (Alanine), valine (Valine), leucine (Leucine), isoleucine (Isoleucine), phenylalanine (Phenylalanine), tryptophan (Tryptophan), tyrosine (Tyrosine), aspartic acid (Aspartic acid), histidine (Histidine), asparagine (Asparagine), glutamic acid (Glutamic acid), lysine (Lysine), glutamine (Glutamine), methionine (Methionine), arginine (Arginine), serine (Serine), threonine (Threonine), cysteine (Cysteine), proline (Proline), etc. Non-natural amino acids such as citrulline. As is well known to those skilled in the art, non-natural amino acids do not constitute natural proteins and thus are not involved in the synthesis of antibodies in the present disclosure. The three-letter and one-letter codes for amino acids used in the present disclosure are as described in J. Biol. Chem., 243, p3558 (1968).

[0684] The term "amino acid unit" refers to a structural fragment containing any natural amino acid or non-natural amino acid, and linking the stretch unit and the spacer unit / or directly linking the toxin molecule.

[0685] The term "ligand-drug conjugate" (LDC) refers to a ligand, such as an antibody, linked to a biologically active drug through a stable linking unit. In the present disclosure, "antibody-drug conjugate" (ADC) refers to a monoclonal antibody or antibody fragment linked to a biologically active toxic drug through a stable linking unit.

[0686] The term "ligand" refers to any macromolecule (e.g., polypeptide or antibody) typically used in ligand-drug-conjugate (e.g., antibody-drug-conjugate) technology.

[0687] The term "antibody" encompasses various antibody structures, including but not limited to monoclonal antibodies, polyclonal antibodies; monospecific antibodies, multispecific antibodies (e.g., bispecific antibodies), full-length antibodies and antibody fragments (or antigen-binding fragments, or antigen-binding portions), as long as they exhibit the desired antigen-binding activity. An antibody can refer to an immunoglobulin, which is a four polypeptide chain structure connected by interchain disulfide bonds, consisting of two heavy chains and two light chains. The immunoglobulin heavy chain constant region has different amino acid compositions and arrangement orders, and thus different antigenicities. Accordingly, the immunoglobulin can be divided into five types, or called isotypes of immunoglobulin, namely IgM, IgD, IgG, IgA and IgE, and the corresponding heavy chains are μ chain, δ chain, γ chain, α chain and ε chain, respectively. The same type of Ig can be divided into different subtypes according to the differences in the amino acid composition of the hinge region and the number and position of the heavy chain disulfide bonds, such as IgG can be divided into IgG1, IgG2, IgG3 and IgG4. The light chain is divided into κ chain or λ chain through the constant region. Each of the five types of Ig can have K chain or λ chain.

[0688] Methods for producing and purifying antibodies and antigen-binding fragments are well known in the art, such as Antibody Engineering Techniques Guide, Cold Spring Harbor, chapters 5-8 and 15. Antigen-binding fragments can also be prepared by conventional methods. The antibodies or antigen-binding fragments described in the invention are genetically engineered to add one or more human FR regions to the CDR regions of non-human origin. Human FR germline sequences can be obtained by aligning the IMGT human antibody variable region germline gene database and MOE software, such as from the website of ImMunoGeneTics (IMGT) http: / / imgt.cines.fr.

[0689] The term "drug loading" refers to the average number of drugs carried by each ligand-drug conjugate molecule, which can also be expressed as the ratio of the amount of drug to the amount of ligand. The drug loading can range from 1 to 20, preferably 1 to 10 cytotoxic drugs (D) per ligand (Ab). In embodiments of the present disclosure, the drug loading is expressed as k (or Dar), which can be exemplarily 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or the average value between any two values. Preferably, the average value is 1-10, more preferably 1-8, or 2-8, or 2-7, or 3-8, or 3-7, or 3-6, or 4-7, or 4-6, or 4-5. The average number of drugs per ADC molecule after conjugation can be identified by conventional methods such as UV / visible spectroscopy, mass spectrometry, ELISA assay, monoclonal antibody size variant assay (CE-SDS) and HPLC.

[0690] The monoclonal antibody size variant assay (CE-SDS) of the present disclosure can use sodium dodecyl sulfate capillary electrophoresis (CE-SDS) ultraviolet detection method to quantitatively determine the purity of recombinant monoclonal antibody products under reducing and non-reducing conditions according to the molecular weight size by capillary electrophoresis method (2015 edition of Chinese Pharmacopoeia 0542).

[0691] In one embodiment of the present disclosure, the cytotoxic drug is conjugated to the N-terminal amino group and / or the ε-amino group of lysine residues of the ligand through the linker unit. Generally, the number of drug molecules that can be conjugated to the ligand in the conjugation reaction will be less than the theoretical maximum.

[0692] The drug loading of the ligand-drug conjugate can be controlled by the following non-limiting methods, including:

[0693] (1) controlling the molar ratio of the linking reagent and the monoclonal antibody,

[0694] (2) controlling the reaction time and temperature,

[0695] (3) selecting different reaction reagents.

[0696] The term "drug" or "drug unit" refers to a compound (e.g., an active pharmaceutical ingredient and its pharmaceutically acceptable salts, a derivative of an active pharmaceutical ingredient and its pharmaceutically acceptable salts, a prodrug modification of an active pharmaceutical ingredient and its pharmaceutically acceptable salts) that has biological activity and provides a desired physiological effect upon administration to a subject in need thereof, including but not limited to: a cytotoxic compound, a cytostatic compound, an immunosuppressive compound, an anti-inflammatory compound, or an anti-infective compound. The cytotoxic compound includes but is not limited to eribulin or its derivatives, trabectedin or its derivatives, auzreotin E or its derivatives, auzreotin E or its derivatives, camptothecin or its analogs. The antibodies of the present disclosure include murine antibodies, chimeric antibodies, humanized antibodies, and fully human antibodies, preferably humanized antibodies and fully human antibodies.

[0697] The term "murine antibody" in the present disclosure is an antibody prepared from a mouse according to the knowledge and skill in the art. The preparation is performed by injecting a test subject with a specific antigen, and then isolating a hybridoma expressing an antibody having a desired sequence or functional property.

[0698] The term "chimeric antibody" is an antibody in which the variable region of a murine antibody is fused with the constant region of a human antibody, which can reduce the immune response reaction induced by the murine antibody. To establish a chimeric antibody, a hybridoma secreting a murine-specific monoclonal antibody is first established, and then the variable region gene is cloned from the murine hybridoma cell, and the constant region gene of the human antibody is cloned as needed, and the murine variable region gene is linked with the human constant region gene to form a chimeric gene, which is inserted into an expression vector, and finally the chimeric antibody molecule is expressed in a eukaryotic system or a prokaryotic system.

[0699] The term "humanized antibody", also known as CDR-grafted antibody, refers to an antibody in which murine CDR sequences are grafted into a human antibody variable region framework, i.e. an antibody generated by grafting different types of human germline antibody framework sequences. The heterogeneity reaction induced by chimeric antibodies due to carrying a large number of murine protein components can be overcome. Such framework sequences can be obtained from public DNA databases or published references including germline antibody gene sequences. The germline DNA sequences of human heavy and light chain variable region genes can be found in the "VBase" human germline sequence database (available on the Internet at www.mrccpe.com.ac.uk / vbase), and in Kabat, E. A. et al., 1991 Sequences of Proteins of Immunological Interest, 5th edition. To avoid the decrease in immunogenicity while causing a decrease in activity, the human antibody variable region framework sequence can be subjected to minimal back mutation or back mutation to maintain activity. The humanized antibodies of the present disclosure also include humanized antibodies further affinity matured by phage display on CDR.

[0700] The term "fully human antibody", "fully human antibody" or "completely human antibody", also known as "fully human monoclonal antibody", is an antibody whose variable region and constant region are both human, removing immunogenicity and toxic side effects. The development of monoclonal antibodies has gone through four stages, namely: murine monoclonal antibody, chimeric monoclonal antibody, humanized monoclonal antibody and fully human monoclonal antibody. The present disclosure is a fully human monoclonal antibody. The related technologies for the preparation of fully human antibodies mainly include: human hybridoma technology, EBV transformed B lymphocyte technology, phage display technology (phage display), transgenic mouse antibody preparation technology (transgenic mouse) and single B cell antibody preparation technology, etc.

[0701] The term "CDR"1 refers to one of six hypervariable regions within the variable domain of an antibody that primarily contribute to antigen binding. One of the most commonly used definitions of the six CDRs is provided by Kabat E. A. et al. (1991) Sequences of proteins of immunological interest. NIH Publication 91-3242. As used herein, the Kabat definition of CDRs applies only to CDR1, CDR2, and CDR3 of the light chain variable domain (CDR L1, CDR L2, CDR L3 or L1, L2, L3), and CDR2 and CDR3 of the heavy chain variable domain (CDR H2, CDR H3 or H2, H3). Generally, there are three CDRs in each heavy chain variable region (HCDR1, HCDR2, HCDR3) and three CDRs in each light chain variable region (LCDR1, LCDR2, LCDR3). The amino acid sequence boundaries of the CDRs can be determined using any of a variety of well-known schemes, including the "Kabat" numbering convention (see Kabat et al. (1991) "Sequences of Proteins of Immunological Interest," 5th Ed., Public Health Service, National Institutes of Health, Bethesda, MD), the "Chothia" numbering convention (see Al-Lazikani et al. (1997) JMB 273:927-948), and the ImMunoGenTics (IMGT) numbering convention (see Lefranc M.P., Immunologist, 7, 132-136 (1999); Lefranc, M.P. et al., Dev. Comp. Immunol., 27, 55-77 (2003)), among others. For example, for the canonical format, following the Kabat convention, the CDR amino acid residues in the heavy chain variable domain (VH) are numbered 31-35 (HCDR1), 50-65 (HCDR2), and 95-102 (HCDR3); and in the light chain variable domain (VL) are numbered 24-34 (LCDR1), 50-56 (LCDR2), and 89-97 (LCDR3). Following the Chothia convention, the CDR amino acid residues in the VH are numbered 26-32 (HCDR1), 52-56 (HCDR2), and 95-102 (HCDR3); and in the VL are numbered 26-32 (LCDR1), 50-52 (LCDR2), and 91-96 (LCDR3).CDRs consist of amino acid residues 26-35 (HCDR1), 50-65 (HCDR2), and 95-102 (HCDR3) in human VH and 24-34 (LCDR1), 50-56 (LCDR2), and 89-97 (LCDR3) in human VL, following the IMGT rules. Following the IMGT rules, the CDR amino acid residue numbering in VH is approximately 26-35 (CDR1), 51-57 (CDR2), and 93-102 (CDR3), and in VL is approximately 27-32 (CDR1), 50-52 (CDR2), and 89-97 (CDR3). CDR regions of an antibody can be determined using the program IMGT / DomainGap Align, following the IMGT rules.

[0702] Amino acid sequence "identity" refers to the percentage of amino acid residues in a first sequence that are identical with the amino acid residues in a second sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity, and not considering any conservative substitutions as part of the sequence identity. Alignment can be achieved in various ways that are within the skill in the art, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN, ALIGN-2, or Megalign (DNASTAR) software. Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared.

[0703] The term "polypeptide" refers to a fragment of a compound between amino acids and proteins, which is composed of two or more amino acid molecules connected to each other by a peptide bond, and is a structural and functional fragment of a protein, such as hormones, enzymes, etc. Peptides are essentially peptides.

[0704] The term "orthogonal linker" refers to a linker unit assembly that links a ligand to a homopolymer unit and a drug unit, such that the homopolymer unit is in a parallel configuration with respect to the drug unit (as opposed to a tandem configuration). The orthogonal linker is a scaffold with attachment sites for the components of a ligand-drug-conjugate (LDC), i.e., the ligand, the homopolymer, and the drug unit.

[0705] The term "parallel" is used to indicate branching of two components of a ligand-drug-conjugate, but is not used to indicate that the two components must be in close spatial proximity or have the same distance between them.

[0706] An exemplary graphical representation of an LDC with homopolymer (e.g., polysarcosine or a derivative thereof) units in a parallel (i.e., branched) orientation with respect to the drug unit is as follows: wherein (L) is an orthogonal linker unit, and w is 1 or greater. In certain embodiments, w is 1-5. In certain embodiments, w is 1-4. In certain embodiments, w is 1-3. In certain embodiments, w is 1 and 2. This orthogonal structure is not to be confused with a linear structure. An example of an LDC with homopolymer (e.g., poly-sarcosine or its derivatives) units in a consecutive (i.e., linear) orientation relative to the drug unit is: Ligand-Homopolymer-Drug.

[0707] The orthogonal linker described in the present disclosure contains, but is not limited to, natural or unnatural amino acids, such as lysine, glutamic acid, aspartic acid, serine, tyrosine, cysteine, selenocysteine, glycine, homoalanine; amino alcohols; amino aldehydes; polyamines or any combination thereof. One skilled in the art is able to select an appropriate orthogonal linker for the intended LDC compound according to common general knowledge. In some embodiments, the orthogonal linker contains one or more natural or unnatural amino acids. In some embodiments, the orthogonal linker can also contain a polyamine. In one embodiment, the orthogonal linker is selected from the group consisting of glutamic acid, lysine, glycine, ornithine, polyamine or any combination thereof. In one embodiment, the orthogonal linker is a lysine residue.

[0708] The term "monomolecular weight homopolymer" or "homopolymer unit" refers to a homopolymer having a unique and specific molecular weight centered around an average molecular weight, as opposed to a mixture of homopolymers of the same nature but having a distribution of sizes and molecular weights. A monomolecular weight homopolymer can be defined with an absolute formula having an absolute number of atoms. The monomolecular weight homopolymer is in contrast to a polydisperse homopolymer, which is traditionally obtained by a one-pot polymerization process and has a polydispersity index (PDI) > 1, which is referred to as "monodisperse" with a PDI equal to 1.

[0709] An inert group or capping group refers to a non-reactive group that terminates any chemical reaction at one end of a polymer, which is non-reactive compared to a functionalized reactive group that terminates the other end of the homopolymer under defined reaction conditions. The resulting polymer is capped in some way by the inert group and is not intended to be covalently linked when used, particularly in LDC technology. In one embodiment, the group only becomes inert after it is covalently bound to one end of the polymer.

[0710] An inert group includes, but is not limited to: acyl (e.g., acetyl), amido, alkyl (e.g., C 1-20 alkyl ether (e.g., C 1-20 alkyl ether), alkyl ester (e.g., C 1-20 alkyl ester), alkyl orthoester (e.g., C 1-20Alkyl orthoester group, alkenyl group, alkynyl group, aryl group, aryl ester group, tertiary amine group, hydroxyl group, aldehyde group. The inert group may also be selected from the same list as the functionalized reactive group.

[0711] A functionalized reactive group is any chemical moiety that is reactive to covalently bondable groups, and is reactive under defined reaction conditions compared to an inert group. Specifically, it can bind to the following groups: carboxylic acids, primary amines, secondary amines, tertiary amines, hydroxyl groups, halogens, esters (e.g., N-hydroxysuccinimide esters, perfluorinated esters, nitrobenzene esters, aza-benzotriazole and benzotriazole activated esters, acylurea), alkynyl groups, alkenyl groups, azides, isocyanates, isothiocyanates, aldehydes, thiol reactive moieties (e.g., maleimides, halomaleimides, haloacetyl groups, pyridyl disulfides), thiols, acrylates, methanesulfonates, toluenesulfonates, trifluoromethanesulfonates, hydroxylamines, chlorosulfonyl groups, and borate-B(OR')2 derivatives, where R' is hydrogen or an alkyl group.

[0712] Functionalized reactive groups include, but are not limited to: carboxylic acids, primary amines, secondary amines, tertiary amines, hydroxyl groups, halogens, esters (e.g., N-hydroxysuccinimide esters, perfluorinated esters, nitrobenzene esters, aza-benzotriazole and activated benzotriazole esters, acylurea), alkynyl groups, alkenyl groups, azides, isocyanates, isothiocyanates, aldehydes, thiol reactive moieties (e.g., maleimide, halomaleimide, haloacetyl, pyridyl disulfide), thiols, acrylates, methanesulfonates, toluenesulfonates, trifluoromethanesulfonates, hydroxylamine, chlorosulfonyl groups, and borate-B(OR')2 derivatives, wherein R' is hydrogen or an alkyl group.

[0713] It should be mentioned that the terms "inert" and "functionalized reactive," used for inert groups and functionalized reactive groups respectively, are interdependent. This means that under specific reaction conditions of the polymer, inert groups will not react, while functionalized reactive groups will react to covalently bind reactants. Therefore, the inert groups and functionalized reactive groups in the polymer are distinct, but they can be selected collectively from the same list of groups.

[0714] The terms “monodisperse” and “disperse” are interchangeable, both defining homopolymers with unique and absolute molecular weights, molecular formulas and molecular structures. The term “monodisperse” does not accurately reflect the preparation process of the product.

[0715] The term "hydrophilic unit" refers to a structural unit that contains hydrophilic groups.

[0716] "Alkyl" refers to saturated aliphatic hydrocarbon groups, both straight-chain and branched, including groups having 1 to 6 carbon atoms. Non-limiting examples include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, sec-butyl, n-pentyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, and various branched isomers of pentyl and the like. Alkyl groups can be substituted or unsubstituted, and when substituted are preferably substituted at any available attachment point with one or more groups independently selected from halo, hydroxy, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy.

[0717] "Alkenyl" refers to unsaturated aliphatic straight-chain or branched hydrocarbon groups and contain one or more carbon-carbon double bonds. Exemplary alkenyl groups include C2-C6, C2-C4, and C3 alkenyl groups. These include, but are not limited to, ethenyl (i.e., vinyl), 1-propenyl, 2-propenyl (i.e., allyl), 2-methyl-l- propenyl, 1-butenyl, 2-butenyl (i.e., crotyl), and the like. Alkenyl groups used in any context herein are optionally substituted in the same manner as alkyl groups.

[0718] "Alkynyl" refers to unsaturated aliphatic straight-chain or branched hydrocarbon groups and contain one or more carbon-carbon triple bonds. Exemplary alkynyl groups include C2-C6, C2-C4, and C3 alkynyl groups. These include, but are not limited to, ethynyl, prop-1-ynyl, but-1-ynyl, pent-1-ynyl, pent-4-ynyl, and pent-1,4-diynyl. Alkynyl groups used in any context herein are optionally substituted in the same manner as alkyl groups.

[0719] The term "cycloalkyl" refers to saturated or partially unsaturated monocyclic or polycyclic cyclic hydrocarbon substituents, the cycloalkyl ring comprising 3 to 6 carbon atoms, such as 4 carbon atoms or 5 carbon atoms. Non-limiting examples of monocyclic cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, and the like; polycyclic cycloalkyl groups include spiro, fused, and bridged cycloalkyl groups. Cycloalkyl groups can be substituted or unsubstituted. When substituted, the substituents are preferably one or more groups independently selected from halo, oxo, hydroxy, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy.

[0720] The term "heterocycloalkyl" refers to saturated or partially unsaturated monocyclic or polycyclic cyclic hydrocarbon substituents comprising 3 to 14 ring atoms, such as 4 ring atoms or 5 ring atoms, wherein one or more ring atoms are selected from nitrogen, oxygen, or S(O) mheteroatoms, but not including -0-0-, -0-S-, or -S-S-, the remaining ring atoms being carbon. "Heterocycloalkyl" includes, but is not limited to: etc.

[0721] Heterocycloalkyl groups can be optionally substituted or unsubstituted, and when substituted, the substituent groups are preferably one or more groups independently selected from halogen, oxo, hydroxy, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy.

[0722] In some embodiments, the heterocycloalkyl group can be fused to an aryl or heteroaryl ring, where the ring that is attached to the parent structure along with the ring is a heterocycloalkyl group.

[0723] In some embodiments, the heterocycloalkyl group is in a polycyclic ring, including "spiro", "fused", or "bridged".

[0724] The term "spiro" refers to a compound in which two rings share one atom. Spiroalkyl groups include, but are not limited to:

[0725] The term "fused" refers to a compound in which two or more rings are joined by sharing two adjacent atoms. Fused heterocycloalkyl groups include, but are not limited to:

[0726] The term "bridged" refers to a structure in which two or more ring structures share two non-adjacent ring atoms with each other. Depending on the number of rings that make up the structure, the bridged heterocycloalkyl group can be bicyclic, tricyclic, tetracyclic, or polycyclic, preferably bicyclic, tricyclic, or tetracyclic, more preferably bicyclic or tricyclic. Bridged heterocycloalkyl groups include, but are not limited to:

[0727] The term "alkoxy" refers to -0-(alkyl), where alkyl is as defined above. Alkoxy groups include, but are not limited to: methoxy, ethoxy, propyloxy, butyloxy. Alkoxy groups can be optionally substituted or unsubstituted, and when substituted, the substituent groups are preferably one or more groups independently selected from halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy.

[0728] The term "aryl" or "aromatic ring" refers to a 6- to 10-membered all-carbon monocyclic or fused polycyclic (that is, rings which share pairs of adjacent carbon atoms) ring having a conjugated pi-electron system, such as phenyl and naphthyl. The aryl ring can be fused to a heteroaryl, heterocycloalkyl, or cycloalkyl ring, where the ring that is attached to the parent structure along with the ring is an aryl ring, including, but not limited to:

[0729] Aryl can be substituted or unsubstituted, and when substituted, the substituents are preferably one or more groups independently selected from halogen, hydroxy, cyano, nitro, amino, C 1-6 Alkyl or C 1-6 Alkoxy.

[0730] The term "heteroaryl" or "heteroaromatic" refers to a heteroaromatic system comprising from 1 to 4 heteroatoms, and from 5 to 10 ring atoms, wherein the heteroatoms are selected from oxygen, sulfur and nitrogen. Heteroaryl is preferably from 5 to 10 members, such as 7, 8 or 9 members, and more preferably 5 or 6 members. For example. It includes, but is not limited to:

[0731] The heteroaryl can be fused to an aryl, heterocycloalkyl or cycloalkyl ring, wherein the ring that is attached to the parent structure is a heteroaryl, which includes, but is not limited to:

[0732] Heteroaryl can be optionally substituted or unsubstituted, and when substituted, the substituents are preferably one or more groups independently selected from halogen, hydroxy, cyano, nitro, amino, C 1-6 Alkyl or C 1-6 Alkoxy.

[0733] The term "heterocycle" refers to a ring composed of atoms other than carbon, including heterocycloalkyl and heteroaryl. "Heterocycloalkyl" and "heteroaryl" are as defined above.

[0734] A "monovalent group" refers to a compound formally eliminating one monovalent atom or group. A "divalent group" refers to a compound formally eliminating two monovalent atoms or one divalent atom or group, such as "methylene" which represents the portion of an alkane molecule remaining after removal of two hydrogen atoms.

[0735] In some embodiments, heterocycloalkyl, heteroaryl can be monovalent, divalent or polyvalent, and one skilled in the art will recognize from the context the number of valences available.

[0736] The term "amino" refers to -N(R a )2, wherein R a are each independently selected from hydrogen, C 1-6 Alkyl, C 3-6 Cycloalkyl or 3- to 6-membered heterocycloalkyl, said alkyl, cycloalkyl or heterocycloalkyl being optionally substituted with one or more groups selected from halogen, hydroxy, cyano, nitro, C 1-6 Alkyl or C 1-6 Alkoxy. In some embodiments, "amino" can be unsubstituted amino (i.e., -NH2) or substituted amino (-N(R a )2, R a is not both hydrogen).

[0737] The term "hydroxy" refers to an -OH group.

[0738] The term "halogen" refers to fluorine, chlorine, bromine, or iodine.

[0739] The term "cyano" refers to -CN.

[0740] The term "nitro" refers to -NO2.

[0741] The term "oxo" refers to =O.

[0742] The term "thioxo" or "thio" refers to =S.

[0743] The term "carbonyl" refers to C=O.

[0744] The term "carboxyl" refers to -C(O)OH.

[0745] "Substituted" means that one or more hydrogen atoms, preferably up to 5, more preferably 1 to 3, of a group are independently of each other replaced by a corresponding number of substituents. It goes without saying that the substituents are only in their possible chemical positions, which can be determined (experimentally or theoretically) by a person skilled in the art without undue effort, as possible or impossible.

[0746] The term "substituent" includes, but is not limited to, halogen, hydroxy, cyano, nitro, amino, C 1-6 alkyl or C 1-6 alkoxy, which alkyl, alkoxy is optionally substituted with one or more substituents selected from the group consisting of halogen, hydroxy, cyano, nitro, C 1-6 alkyl or C 1-6 alkoxy. In the present disclosure, "alkyl", "alkoxy" or "cycloalkyl" is optionally substituted with the aforementioned substituents, which substitution maintains the same or similar pharmacodynamic or functional properties.

[0747] In the present disclosure, the numerical values are measured values of instruments, which have a certain degree of error. Generally speaking, plus or minus 10% is within a reasonable error range. Of course, the context in which the numerical value is used needs to be considered, for example, the amount of reactants charged, the error change after measurement is not more than plus or minus 10%, which can be plus or minus 9%, plus or minus 8%, plus or minus 7%, plus or minus 6%, plus or minus 5%, plus or minus 4%, plus or minus 3%, plus or minus 2%, or plus or minus 1%, preferably plus or minus 5%.

[0748] The protecting groups in the present disclosure are those known in the art that can be used to protect amino / carboxyl groups, see the amino / carboxyl protecting groups in the literature (Protective Groups in Organic Synthesis, 5Th Ed. T. W. Greene & P. G. M. Wuts). As examples, but not limited to, methyl, methoxy, ethoxy, and the like.

[0749] Abbreviations used in the present disclosure are as follows: DETAILED DESCRIPTION

[0750] The preparation of the compounds, pharmaceutically acceptable salts described in the present disclosure are further described below in connection with the examples, but these examples are not limiting the scope of the present disclosure.

[0751] The experimental methods in the examples in the present disclosure, unless otherwise specified, are generally performed according to the conventional conditions, or according to the conditions suggested by the manufacturer of the raw materials or commodities. The reagents, unless otherwise specified, are commercially available conventional reagents.

[0752] The structure of the compounds is determined by nuclear magnetic resonance (NMR) or / and mass spectrometry (MS). The NMR shift (δ) is given in units of 10 -6 (ppm). The NMR is measured by a Bruker AVANCE-400 NMR spectrometer or a Bruker AVANCE NEO 500M, with deuterated dimethyl sulfoxide (DMSO-d6), deuterated chloroform (CDCl3), deuterated methanol (CD3OD) as the solvent, and tetramethylsilane (TMS) as the internal standard.

[0753] The MS is measured by an Agilent 1200 / 1290 DAD-6110 / 6120 Quadrupole MS liquid chromatograph-mass spectrometer (manufacturer: Agilent, MS model: 6110 / 6120 Quadrupole MS).

[0754] waters ACQuity UPLC-QD / SQD (manufacturer: waters, MS model: waters ACQuity Qda Detector / waters SQ Detector)

[0755] THERMO Ultimate 3000-Q Exactive (manufacturer: THERMO, MS model: THERMO Q Exactive)

[0756] High performance liquid chromatography (HPLC) analysis used Agilent HPLC 1200 DAD, Agilent HPLC 1200 VWD and Waters HPLC e2695-2489 high performance liquid chromatograph.

[0757] Chiral HPLC analysis determination used Agilent 1260 DAD high performance liquid chromatograph.

[0758] High performance liquid preparation used Waters 2545-2767, Waters 2767-SQ Detecor2, Shimadzu LC-20AP and Gilson GX-281 preparative chromatograph.

[0759] Chiral preparation used Shimadzu LC-20AP preparative chromatograph.

[0760] CombiFlash rapid preparation instrument used Combiflash Rf200 (TELEDYNE ISCO).

[0761] Thin layer chromatography silica gel plate used Yantai Huanghai HSGF254 or Qingdao GF254 silica gel plate, the specification of silica gel plate used in thin layer chromatography (TLC) was 0.15mm-0.2mm, and the specification of thin layer chromatography separation and purification product was 0.4mm-0.5mm.

[0762] Silica gel column chromatography generally used Yantai Huanghai silica gel 200-300 mesh silica gel as carrier.

[0763] Determination of average inhibition rate and IC 50 values of kinase used NovoStar microplate reader (Germany BMG company).

[0764] Known starting materials of the present disclosure can be synthesized or purchased from ABCR GmbH & Co. KG, Acros Organics, Aldrich Chemical Company, Accela ChemBio Inc, Daejeon Chemicals and the like according to methods known in the art.

[0765] Unless otherwise specified in the examples, the reactions were carried out under argon or nitrogen atmosphere.

[0766] Argon or nitrogen atmosphere refers to that the reaction bottle is connected with an argon or nitrogen balloon with a volume of about 1L.

[0767] Hydrogen atmosphere refers to that the reaction bottle is connected with a hydrogen balloon with a volume of about 1L.

[0768] The pressurized hydrogenation reaction uses a Parr 3916EKX hydrogenation instrument and a Qinglan QL-500 hydrogen generator or an HC2-SS hydrogenation instrument.

[0769] The hydrogenation reaction is usually vacuumed, filled with hydrogen, and repeated 3 times.

[0770] The microwave reaction uses a CEM Discover-S 908860 microwave reactor.

[0771] In the examples, unless otherwise specified, the solution refers to an aqueous solution.

[0772] In the examples, unless otherwise specified, the reaction temperature is room temperature, which is 20-30°C.

[0773] In the examples, the monitoring of the reaction progress uses thin layer chromatography (TLC), and the solvent volume ratio of the developing agent used in the reaction, the eluent used in column chromatography for purifying compounds, and the developing agent system of thin layer chromatography is adjusted according to the polarity of the compound. A small amount of basic or acidic reagent such as triethylamine and acetic acid can also be added for adjustment.

[0774] The general detection method of the present disclosure includes:

[0775] 1) RP analysis:

[0776] Instrument: Agilent 1260 Infinity II

[0777] Column: PLRP-S (8 μm*4.6 mm*250 mm)

[0778] Mobile phase: A phase: A: 0.1% TFA in H2O, B phase: B: 0.1% TFA in ACN

[0779] Flow rate: 1.0 mL / min, column temperature: 80°C

[0780] 2) Mass spectrometry analysis:

[0781] Instrument: High-resolution mass spectrometer (Thermo QEXACTIVE HF-X) and ultra-high performance liquid chromatograph (Thermo Vanquish UHPLC)

[0782] Column: ACQUITY UPLC Protein BEH C4 Column, 1.7 μm, 2.1 mm X 50 mm (186004495, Waters)

[0783] Mobile phase: Mobile phase A is 0.1% FA aqueous solution, and mobile phase B is 0.1% FA acetonitrile solution

[0784] Flow rate: 0.25 mL / min;

[0785] Column temperature: 80℃

[0786] 3) SDS-PAGE gel electrophoresis experiment

[0787] (1) Pretreatment of protein sample: Take 3 μL of 1 mg / mL protein sample, add 5 μL of 4xLoading Buffer and 4 μL of PBS 7.2, denature at 100℃ for 10 min, then centrifuge at 10000 rpm for 3 min, take the supernatant;

[0788] (2) Spotting: Assemble a 4%-20% precast gel plate (Genscript, C35152403) into an electrophoresis tank, dilute 20x electrophoresis solution (Genscript, C36802402) to 1 L, add to the electrophoresis tank, add the above protein sample, and set the protein Marker as a reference;

[0789] (3) Electrophoresis: Set 170V constant voltage electrophoresis, run for about 30 min, until the bromophenol blue indicator runs to the bottom end of the glass plate, stop electrophoresis, and take out the gel plate;

[0790] (4) After electrophoresis, use a protein staining instrument to stain, and then repeatedly decolorize with ultrapure water until the gel background is colorless.

[0791] Preparation of compound 1 of Example 1

[0792] Step 1:

[0793] Compound 1a (1.25 g, 0.97 mmol, prepared by a known method "WO2023 / 280227") was dissolved in anhydrous DMF (20 mL), and the system was protected by nitrogen. Piperidine (0.25 g, 2.90 mmol) was added, and the reaction was carried out at room temperature for 30 min. The reaction was complete, MTBE 120 mL was added to the slurry for 10 min, filtered, washed with MTBE 20 mL, and the solid was collected to obtain about 1.0 g of compound 1b (yield: 96.6%).

[0794] MS (ESI): m / z 1069.5 [M+1] + .

[0795] Step 2:

[0796] Compound 1b (1.0 g, 0.94 mmol), FmocNH-PEG-Acid (0.46 g, 0.94 mmol, purchased from GenScript) were dissolved in anhydrous DMF (20 mL), the system was protected by nitrogen, DIPEA (0.36 g, 2.81 mmol), HATU (0.43 g, 1.12 mmol) were added, and the reaction was carried out at room temperature for 30 min. After the reaction was completed, MTBE 120 mL was added to the slurry, filtered, washed with MTBE 20 mL, and the solid was collected to obtain about 1.26 g of compound 1c (yield: 87.6%).

[0797] MS (ESI): m / z 1538.6 [M+1] + .

[0798] Step 3:

[0799] Compound 1c (1.2 g, 0.78 mmol) was dissolved in anhydrous DCM (20 mL), the system was protected by nitrogen, TFA (2 mL) was added, and the reaction was carried out at room temperature. After the reaction was completed, the crude product was added to anhydrous DMF 20 mL and stirred to dissolve, then MTBE 120 mL was added to the slurry, filtered, washed with MTBE 20 mL, and the solid was collected to obtain about 1.05 g of compound 1d (yield: 93.6%).

[0800] MS (ESI): m / z 1438.6 [M+1] + .

[0801] Step 4:

[0802] Compound 1d (153 mg, 106.35 μmol), compound 1g (102 mg, 112.09 μmol), DIPEA (60 μL, 344.47 μmol), HATU (58 mg, 152.54 μmol) were dissolved in DMF (3 mL) and stirred at room temperature for 2 hours. Methyl tert-butyl ether (30 mL) was added to the reaction solution, and after stirring for 1 hour, 258 mg of compound 1e was obtained (yield 104.09%).

[0803] MS (ESI): m / z 1165.8 [M / 2+1] + .

[0804] Step 5:

[0805] Compound 1e (262 mg, 112.42 μmol) was dissolved in DMF (3 mL), and piperidine (50 μL) was added, and the reaction was carried out at room temperature for 2 hours. The reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to obtain 117 mg of compound 1f (yield 49.36%).

[0806] MS (ESI): m / z 1054.7 [M / 2+1] + .

[0807] Step 6:

[0808] Compound 1f (117 mg, 55.49 pmol), trans-2,5-dioxopyrrolidin-1-yl 4-((2,5-dioxo-2,5- dihydro-1H-pyrrol-1-yl)methyl)cyclohexanecarboxylate (23 mg, 68.80 pmol, purchased from Adamas) were dissolved in DMF (2.1 mL), triethylamine (25 pL, 179.37 pmol) was added, stirred at room temperature, and the reaction was monitored until the starting material was consumed. The reaction was purified by reverse phase preparative chromatography (ACN / H20 with 0.1% HCOOH) to give 48 mg of compound 1 (yield 37.16%).

[0809] MS (ESI): m / z 1164.6 [M / 2+1] + .

[0810] Preparation of compound 1g

[0811] Step 1:

[0812] Compound 1g-1 (1.65 g, 3.01 mmol) and Ac-Sar-(6) (2.26 g, 4.66 mmol, prepared according to the method of WO2019 / 81455), HATU (1.53 g, 4.03 mmol) were dissolved in DCM (35 mL), protected by nitrogen, DIEA (1.60 g, 12.41 mmol) was added, and the reaction was allowed to proceed at room temperature for 1 hour. 35 mL of water was added, and the mixture was extracted with dichloromethane. The organic phases were combined, concentrated to dryness, and purified by column (AcN: H20 = 0: 100-30: 70) to give 2.14 g of compound 1g-2 (yield 68.94%).

[0813] MS (ESI): m / z 1000.5 [M+1] + .

[0814] Step 2:

[0815] Compound 1g-2 (2.14 g, 2.14 mmol) was dissolved in methanol (25 mL), 10% palladium carbon (467 mg) was added, and the reaction was allowed to proceed at room temperature for 1 hour under hydrogen balloon gas replacement. The reaction was filtered, the filter cake was washed with methanol, and the filtrate was concentrated to dryness to give 1.90 g of compound 1g (yield 97.58%).

[0816] MS (ESI): m / z 910.5 [M+1] + .

[0817] Preparation of compound 2 of Example 2

[0818] Step 1:

[0819] Compound 1d (750 mg, 521.34 μmol), compound 2c (490 mg, 596.17 μmol), DIPEA (350 μL, 2.01 mmol), HATU (262 mg, 689.06 μmol) were dissolved in DMF (10 mL) and stirred at room temperature for 2.5 hours. Methyl tert-butyl ether (100 mL) was added to the reaction solution, and after stirring for 1 hour, 1.44 g of compound 2a (yield 123.17%) was obtained as a crude product by filtration.

[0820] MS (ESI): m / z 1121.7 [M / 2+1] + .

[0821] Step 2:

[0822] Compound 2a (1.44 g, about 520 μmol) was dissolved in DMF (3 mL), and piperidine (305 mg, 3.59 mmol) was added, and stirred at room temperature for 2 hours. The reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to obtain 242 mg of compound 2b (yield 18.65%).

[0823] MS (ESI): m / z 1010.7 [M / 2+1]+.

[0824] Step 3:

[0825] Compound 2b (240 mg, 118.80 μmol), trans-2,5-dioxopyrrolidin-1-yl 4-((2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)cyclohexanecarboxylate (48 mg, 143.57 μmol, purchased from Adamas) were dissolved in DMF (5 mL), and triethylamine (50 μL, 358.73 μmol) was added, and stirred at room temperature for 2.5 hours. The reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to obtain 105 mg of compound 2 (yield 39.47%).

[0826] MS (ESI): m / z 1120.2 [M / 2+1] + .

[0827] 1H NMR (400 MHz, DMSO): δ 10.03 (s, 1H), 8.15-8.01 (m, 3H), 7.81-7.77 (m, 2H), 7.74-7.69 (m, 2H), 7.60 (d, 2H), 7.36 (d, 2H), 7.31 (s, 1H), 7.00 (s, 2H), 6.52 (s, 1H), 5.99 (t, 1H), 5.44 (d, 4H), 5.34-5.24 (m, 3H), 5.08 (s, 2H), 4.40-3.85 (m, 15H), 3.60-3.55 (m, 4H), 3.49-3.13 (m, 55H), 3.05-2.67 (m, 19H), 2.44-1.20 (m, 28H), 0.89-0.81 (m, 9H).

[0828] Preparation of compound 2c

[0829] Step 1:

[0830] Compound 2c-1 (3.00 g, 6.61 mmol, purchased from Leyue), K2CO3 (2.74 g, 19.84 mmol) and NaI (99 mg, 661.49 μmol) were dissolved in DMF (30 mL), protected by nitrogen, and then benzyl bromide (1.70 g, 9.92 mmol, purchased from Adamas) was added after the ice water bath was raised to room temperature for 16 hours. 90 mL of water was added, and dichloromethane was extracted. The organic phase was combined, concentrated to dryness, and purified by column (PE:EA = 100:0-40:60) to obtain 3.30 g of compound 2c-2 (yield 91.77%).

[0831] MS (ESI): m / z 544.5 [M+1] + .

[0832] Step 2:

[0833] Compound 2c-2 (3.30 g, 6.07 mmol) was dissolved in dichloromethane (8 mL) and stirred at room temperature, and HCl / 1,4-dioxane (7.59 mL, 30.35 mmol, 4M) was added, and the reaction was carried out at room temperature for 1 hour. The reaction solution was concentrated to dryness to obtain 3.0 g of compound 2c-3 (yield 102.97%).

[0834] MS (ESI): m / z 444.3 [M+1] + .

[0835] Step 3:

[0836] Compound 2c-3 (1.70 g, 3.54 mmol) and Ac-Sar-(6) (2.58 g, 5.31 mmol, prepared according to the method of WO2019 / 81455), HATU (1.76 g, 4.60 mmol) were dissolved in DCM (35 mL), protected by nitrogen, DIEA (2.29 g, 17.71 mmol) was added, and the reaction was allowed to proceed at room temperature for 1 hour. 35 mL of water was added, and dichloromethane was used for extraction. The organic phases were combined, concentrated to dryness, and purified by column (AcN: H2O = 0: 100-25: 75) to obtain 2.4 g of compound 2c-4 (yield 74.30%).

[0837] MS (ESI): m / z 912.4 [M+1] + .

[0838] Step 4:

[0839] Compound 2c-4 (2.4 g, 2.63 mmol) was dissolved in methanol (48 mL), 10% palladium carbon (480 mg) was added, and the reaction was allowed to proceed at room temperature for 1 hour under hydrogen balloon gas replacement. The reaction liquid was filtered, the filter cake was washed with methanol, and the filtrate was concentrated to dryness to obtain 2.10 g of compound 2c (yield 97.09%).

[0840] MS (ESI): m / z 822.4 [M+1] + .

[0841] Preparation of compound 3 of Example 3

[0842] Step 1:

[0843] Compound 1d (100 mg, 64.41 μmol), compound 3c (68.00 mg, 88.56 μmol), DIPEA (40 μL, 229.64 μmol), HATU (37 mg, 97.31 μmol) were dissolved in DMF (2 mL), and the reaction was allowed to proceed at room temperature for 2 hours. Methyl tert-butyl ether (20 mL) was added to the reaction liquid, and after stirring for 1 hour, 177 mg of compound 3a was obtained (yield 125.57%).

[0844] MS (ESI): m / z 1095.1 [M / 2+1] + .

[0845] Step 2:

[0846] Compound 3a (177 mg, about 64 μmol) was dissolved in DMF (3 mL), piperidine (21 μL) was added, and the mixture was stirred at room temperature for 2.5 hours. The reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to obtain 53 mg of compound 3b (yield 42.14%).

[0847] MS (ESI): m / z 984.0 [M / 2+1]+.

[0848] Step 3:

[0849] Compound 3b (53 mg, 26.96 μmol), trans-2,5-dioxopyrrolidin-l-yl 4-((2,5-dioxo-2,5- dihydro-lH-pyrrol-l-yl)methyl)cyclohexanecarboxylate (11.1 mg, 33.20 μmol, purchased from Leiyuan) were dissolved in DMF (2.5 mL), triethylamine (15 μL, 107.62 μmol) was added, and the mixture was stirred at room temperature until the starting material was completely consumed. The reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to obtain 13 mg of compound 3 (yield 22.07%).

[0850] MS (ESI): m / z 1093.8 [M / 2+1] + .

[0851] Preparation of compound 3c

[0852] Step 1:

[0853] Compound 3c-1 (4.00 g, 7.39 mmol, purchased from Leiyuan), K2CO3 (3.06 g, 22.16 mmol) and NaI (111 mg, 738.51 μmol) were dissolved in DMF (40 mL), and benzyl bromide (1.89 g, 11.08 mmol, purchased from Adamas) was added after the ice water bath was removed. The mixture was stirred at room temperature for 16 hours. 120 mL of water was added, and the mixture was extracted with dichloromethane. The organic phases were combined, concentrated to dryness, and purified by column chromatography (PE:EA = 100:0-20:80) to obtain 4.30 g of compound 3c-2 (yield 92.16%).

[0854] MS (ESI): m / z 632.5 [M+1] + .

[0855] Step 2:

[0856] Compound 3c-2 (4.30 g, 6.81 mmol) was dissolved in dichloromethane (9 mL) and stirred at room temperature, HCl / 1,4-dioxane (8.51 mL, 34.03 mmol, 4 M) was added, and the reaction was allowed to proceed at room temperature for 1 h. The reaction was concentrated to dryness to obtain 4.0 g of compound 3c-3 (yield 103.45%).

[0857] MS (ESI): m / z 532.4 [M+1] + .

[0858] Step 3:

[0859] Compound 3c-3 (500 mg, 880.13 pmol) and Ac-Sar-(4) (454 mg, 1.32 mmol, prepared according to the method of WO2019 / 81455), HATU (437 mg, 1.14 mmol) were dissolved in DCM (10 mL) and protected with nitrogen, DIEA (569 mg, 4.40 mmol) was added, and the reaction was allowed to proceed at room temperature for 1 h. 10 mL of water was added, and extraction was performed with dichloromethane. The organic phases were combined, concentrated to dryness, and purified by column (AcN: H2O = 0: 100-25: 75) to obtain 720 mg of compound 3c-4 (yield 95.35%).

[0860] MS (ESI): m / z 858.4 [M+1] + .

[0861] Step 4:

[0862] Compound 3c-4 (720 mg, 839.16 pmol) was dissolved in methanol (15 mL), 10% palladium carbon (144 mg) was added, and the reaction was allowed to proceed at room temperature for 1 h under hydrogen balloon gas replacement. The reaction was filtered, the filter cake was washed with methanol, and the filtrate was concentrated to dryness to obtain 620 mg of compound 3c (yield 96.22%).

[0863] MS (ESI): m / z 768.4 [M+1] + .

[0864] Preparation of compound 4 of Example 4

[0865] Step 1:

[0866] Compound 1d (95 mg, 61.19 μmol), compound 4c (68 mg, 77.63 μmol), DIPEA (40 μL, 229.64 μmol), HATU (38 mg, 99.94 μmol) were dissolved in DMF (2 mL) and stirred at room temperature for 2.5 hours. Methyl tert-butyl ether (25 mL) was added to the reaction solution, and after stirring for 1 hour, 180 mg of compound 4a was obtained as a crude product (yield 128.10%).

[0867] MS (ESI): m / z 1148.7 [M / 2+1] + .

[0868] Step 2:

[0869] Compound 4a (180 mg, about 61 μmol) was dissolved in DMF (3 mL), and piperidine (21 μL) was added, and stirred at room temperature for 2.5 hours. The reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to obtain 42 mg of compound 4b (yield 33.21%).

[0870] MS (ESI): m / z 1038.1 [M / 2+1] + .

[0871] Step 3:

[0872] Compound 4b (42 mg, 20.25 μmol), trans-2,5-dioxopyrrolidin-1-yl 4-((2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)cyclohexanecarboxylate (9.0 mg, 26.92 μmol, purchased from GL Biochem) were dissolved in DMF (2.5 mL), and triethylamine (15 μL, 107.62 μmol) was added, and stirred at room temperature until the starting material was completely reacted. The reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to obtain 18 mg of compound 4 (yield 38.76%).

[0873] MS (ESI): m / z 1147.3 [M / 2+1] + .

[0874] Preparation of compound 4c

[0875] Step 1:

[0876] Compound 4c-1 (4.90 g, 13.41 mmol, purchased from Bide), K2CO3(5.56 g, 40.23 mmol) and Nal (201 mg, 1.34 mmol) were dissolved in DMF (50 mL), protected by nitrogen, after the addition of benzyl bromide (3.44 g, 20.11 mmol, purchased from Adamas) in ice water bath, and then naturally raised to room temperature for 16 hours. 150 mL of water was added, and dichloromethane was extracted. The organic phase was combined, concentrated to dryness, and purified by column (PE:EA = 100:0-40:60) to obtain 5.56 g of compound 4c-2 (yield 91.02%).

[0877] MS (ESI): m / z 456.4 [M+1] + .

[0878] Step 2:

[0879] Compound 4c-2 (5.50 g, 12.07 mmol) was dissolved in dichloromethane (15 mL) and stirred at room temperature, and HCl / 1,4-dioxane (15 mL, 60.37 mmol, 4M) was added, and reacted at room temperature for 1 hour. The reaction solution was concentrated to dryness to obtain 5.0 g of compound 4c-3 (yield 105.68%).

[0880] MS (ESI): m / z 356.3 [M+1] + .

[0881] Step 3:

[0882] Compound 4c-3 (105 mg, 267.93 μmol) and Ac-Sar-(8) (252 mg, 401.89 μmol, prepared according to the method of WO2019 / 81455), HATU (133 mg, 348.31 μmol) were dissolved in DCM (2 mL), protected by nitrogen, DIEA (173 mg, 1.34 mmol) was added, and reacted at room temperature for 1 hour. 2 mL of water was added, and dichloromethane was extracted. The organic phase was combined, concentrated to dryness, and purified by column (ACN:H2O = 0:100-25:75) to obtain 230 mg of compound 4c-4 (yield 88.85%).

[0883] MS (ESI): m / z 966.4 [M+1] + .

[0884] Step 4:

[0885] Compound 4c-4 (230 mg, 238.07 μmol) was dissolved in methanol (5 mL), 10% palladium carbon (46 mg) was added, hydrogen balloon gas was replaced, and the reaction was stirred at room temperature for 1 hour. The reaction solution was filtered, the filter cake was washed with methanol, and the filtrate was concentrated to dryness to obtain 200 mg of compound 4c (yield 95.90%).

[0886] MS (ESI): m / z 876.4 [M+1] + .

[0887] Preparation of compound 5 of Example 5

[0888] Step 1:

[0889] Compound 1d (197 mg, 126.88 μmol), 21-(Boc-amino)-4,7,10,13,16,19- hexaoxa-heneicosanoic acid (79 mg, 174.19 μmol, purchased from Leagene), DIPEA (117 mg, 905.27 μmol), and HATU (59 mg, 155.17 μmol) were dissolved in DMF (2.5 mL) and stirred at room temperature for 2.5 hours. The reaction solution was purified by reverse phase column chromatography (ACN:H2O = 0:100-30:70, followed by MeOH:H2O = 30:70-100:0) to obtain 192 mg of compound 5a (yield 80.74%).

[0890] MS (ESI): m / z 1874.7 [M+1] + .

[0891] Step 2:

[0892] Compound 5a (101 mg, 53.89 μmol) was dissolved in dichloromethane (1.5 mL), trifluoroacetic acid (200 μL) was added, and the reaction was stirred at room temperature for 3.5 hours. Methyl tert-butyl ether (25 mL) was added to the reaction solution, and after stirring for 1 hour, the reaction was filtered to obtain 118 mg of compound 5b as a crude product (yield 115.97%).

[0893] MS (ESI): m / z 1774.7 [M+1] + .

[0894] Step 3:

[0895] Compound 5b (112 mg, 63.13 pmol), Ac-sar-(8) (49 mg, 77.94 pmol, prepared by referring to the method of WO2019 / 81455), TCFH (33 mg, 117.61 pmol) were dissolved in DMF (3 mL), NMI (50 pL, 627.86 pmol) was added, and the mixture was stirred at room temperature for 3 h. The reaction solution was purified by reversed-phase column chromatography (ACN:H2O = 0:100-10:90, followed by MeOH:H2O = 10:90-100:0) to give 91 mg of compound 5c (yield 60.44%).

[0896] MS (ESI): m / z 1192.8 [M / 2+1] + .

[0897] Step 4:

[0898] Compound 5c (98 mg, 41.10 pmol) was dissolved in DMF (2 mL), piperidine (15 pL) was added, and the mixture was stirred at room temperature for 2 h. The reaction solution was purified by reversed-phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to give 50 mg of compound 5d (yield 56.26%).

[0899] MS (ESI): m / z 1081.7 [M / 2+1] + .

[0900] Step 5:

[0901] Compound 5d (50 mg, 23.12 pmol), trans-2,5-dioxopyrrolidin-1-yl 4-((2,5-dioxo-2,5- dihydro-1H-pyrrol-1-yl)methyl)cyclohexanecarboxylate (11.7 mg, 35.00 pmol, purchased from Adamas) were dissolved in DMF (2 mL), DIPEA (15 pL, 86.12 pmol) was added, and the mixture was stirred at room temperature until the starting material was completely consumed. The reaction solution was purified by reversed-phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to give 19.5 mg of compound 5 (yield 35.41%).

[0902] MS (ESI): m / z 1191.7 [M / 2+1] + .

[0903] Preparation of compound 6 of Example 6

[0904] Step 1:

[0905] Compound 1d (107 mg, 68.92 μmol), compound 6c (665 mg, 88.58 μmol), DIPEA (40 μL, 229.64 μmol), HATU (42 mg, 110.46 μmol) were dissolved in DMF (2 mL) and stirred at room temperature for 2.5 hours. Methyl tert-butyl ether (25 mL) was added to the reaction solution, and after stirring for 1 hour, 177 mg of compound 6a was obtained as a crude product (yield 119.21%).

[0906] MS (ESI): m / z 1078.1 [M / 2+1] + .

[0907] Step 2:

[0908] Compound 6a (177 mg, about 69 μmol) was dissolved in DMF (3 mL), and piperidine (25 μL) was added. The mixture was stirred at room temperature for 2.5 hours. The reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to obtain 69 mg of compound 6b (yield 51.82%).

[0909] MS (ESI): m / z 1933.6 [M+1] + .

[0910] Step 3:

[0911] Compound 6b (69 mg, 35.71 μmol), trans-2,5-dioxopyrrolidin-1-yl 4-((2,5-dioxo-2,5-dihydro-1H-pyrrol-1-yl)methyl)cyclohexanecarboxylate (15 mg, 44.87 μmol, purchased from GL Biochem) were dissolved in DMF (2.5 mL), and triethylamine (20 μL, 143.49 μmol) was added. The mixture was stirred at room temperature until the starting material was completely consumed. The reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to obtain 12 mg of compound 6 (yield 15.62%).

[0912] MS (ESI): m / z 1076.5 [M / 2+1] + .

[0913] Preparation of compound 6c

[0914] Step 1:

[0915] Compound 4c-3 (500 mg, 1.28 mmol) and Ac-Sar-(6) (931 mg, 1.91 mmol, prepared by referring to the method of WO2019 / 81455), HATU (634 mg, 1.66 mmol) were dissolved in DCM (10 mL), protected by nitrogen, DIEA (825 mg, 6.38 mmol) was added, and the reaction was carried out at room temperature for 1 hour. 10 mL of water was added, and dichloromethane was extracted. The organic phases were combined, concentrated to dryness, and purified by column (AcN: H2O = 0: 100-25: 75) to obtain 970 mg of compound 6c-1 (yield 92.27%).

[0916] MS (ESI): m / z 824.3 [M+1] + .

[0917] Step 2:

[0918] Compound 6c-1 (960 mg, 1.17 mmol) was dissolved in methanol (20 mL), 10% palladium carbon (192 mg) was added, and the hydrogen gas balloon was replaced, and the reaction was carried out at room temperature for 1 hour. The reaction liquid was filtered, the filter cake was washed with methanol, and the filtrate was concentrated to dryness to obtain 850 mg of compound 6c (yield 99.42%).

[0919] MS (ESI): m / z 734.4 [M+1] + .

[0920] Preparation of compound 7 of Example 7

[0921] Step 1:

[0922] Compound 7a (0.9 g, 0.92 mmol, prepared by using the known method "WO2022058395") was dissolved in anhydrous DMF (15 mL), the system was protected by nitrogen, piperidine (0.23 g, 2.76 mmol) was added, and the reaction was carried out at room temperature for 30 min. The control raw material was completely reacted, 120 mL of MTBE was added to the slurry, filtered, washed with 20 mL of MTBE, and the solid was collected to obtain about 0.6 g of compound 7b (yield: 86.6%).

[0923] MS (ESI): m / z 755.4 [M+1] + .

[0924] Step 2:

[0925] Compound 7b (0.6 g, 0.79 mmol), compound 7c (0.37 g, 0.79 mmol, purchased from Shaoyuan) were dissolved in anhydrous DMF (12 mL), the system was protected by nitrogen, DIPEA (0.31 g, 2.41 mmol), HATU (0.36 g, 0.95 mmol) were added, and the reaction was carried out at room temperature for 30 min. After the reaction of the raw material was completed, MTBE 100 mL was added to make a slurry, filtered, washed with MTBE 20 mL, and the solid was collected to obtain compound 7d about 0.76 g (yield: 79.3%).

[0926] MS (ESI): m / z 1205.4 [M+1] + .

[0927] Step 3:

[0928] Compound 7d (0.22 g, 0.18 mmol) was dissolved in anhydrous DMF (6 mL), the system was protected by nitrogen, piperidine (0.17 g, 1.83 mmol) was added, and the reaction was carried out at room temperature for 30 min. After the reaction of the raw material was completed, MTBE 60 mL was added to make a slurry, filtered, washed with MTBE 10 mL, and the solid was collected to obtain compound 7e about 0.14 g (yield: 78.2%).

[0929] MS (ESI): m / z 983.4 [M+1] + .

[0930] Step 4:

[0931] Compound 7e (0.14 g, 0.14 mmol), FmocNH-PEG-Acid (0.069 g, 0.14 mmol, purchased from Hanlai Biology) were dissolved in anhydrous DMF (8 mL), the system was protected by nitrogen, DIPEA (0.055 g, 0.43 mmol), HATU (0.065 g, 0.17 mmol) were added, and the reaction was carried out at room temperature for 30 min. After the reaction of the raw material was completed, MTBE 100 mL was added to make a slurry, filtered, washed with MTBE 20 mL, and the solid was collected to obtain compound 7f about 0.19 g (yield: 91.8%).

[0932] MS (ESI): m / z 1452.5 [M+1] + .

[0933] Step 5:

[0934] Compound 7f (0.19 g, 0.13 mmol, known compound) was dissolved in anhydrous DCM (10 mL),

[0935] The system was protected by nitrogen, TFA (1 mL) was added, and the mixture was stirred at room temperature for 1 h. The reaction was complete, and the mixture was concentrated. The crude product was dissolved in 10 mL of anhydrous DMF, and then 100 mL of MTBE was added to the mixture. The mixture was filtered, and the solid was collected. The solid was washed with 10 mL of MTBE to obtain compound 7g (about 0.17 g, yield: 96.1%).

[0936] MS (ESI): m / z 1352.5 [M+1] + .

[0937] Step 6:

[0938] Compound 7g (0.17 g, 0.13 mmol) and compound 2c (0.11 g, 0.13 mmol) were dissolved in 5 mL of anhydrous DMF. The system was protected by nitrogen, and DIPEA (0.049 g, 0.38 mmol) and HATU (0.056 g, 0.15 mmol) were added. The mixture was stirred at room temperature for 30 min. The reaction was complete, and 100 mL of MTBE was added to the mixture. The mixture was filtered, and the solid was collected. The solid was washed with 20 mL of MTBE to obtain compound 7h (about 0.22 g, yield: 81.2%).

[0939] MS (ESI): m / z 1079.1 [M / 2+1] + .

[0940] Step 7:

[0941] Compound 7h (0.22 g, 0.10 mmol) was dissolved in 5 mL of anhydrous DMF. The system was protected by nitrogen, and piperidine (0.026 g, 0.31 mmol) was added. The mixture was stirred at room temperature for 30 min. The reaction was complete, and the mixture was purified by reverse-phase preparative chromatography (ACN / H2O with 0.1% HCOOH). The product was obtained by lyophilization (about 0.08 g, yield: 40.5%).

[0942] MS (ESI): m / z 1933.8 [M+1] + .

[0943] Step 8:

[0944] Compound 7i (0.08 g, 0.04 mmol), trans-2,5-dioxopyrrolidin-l-yl 4-((2,5-dioxo-2,5- dihydro-lH-pyrrol-l-yl)methyl)cyclohexanecarboxylate (0.04 g, 0.04 mmol, purchased from GL Biochem) were dissolved in anhydrous DMF (5 mL), the system was protected by nitrogen, TEA (0.013 g, 0.12 mmol) was added, and the reaction was carried out at room temperature for 30 min. After the completion of the reaction, the reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH), and compound 7 was obtained by freeze-drying, about 0.026 g (yield: 29.2%).

[0945] MS (ESI): m / z 1077.2 [M / 2+1] + .

[0946] Preparation of compound 8 of Example 8

[0947] Step 1:

[0948] Compound Id (220 mg, 152.93 μmol), Ac-sar-(12) (171 mg, 187.30 μmol, prepared by using the known method “WO2019081455”), TCFH (111 mg, 395.61 μmol) were dissolved in DMF (3 mL), NMI (65 μL, 816.22 μmol) was added, and the reaction was carried out at room temperature for 2 h. The reaction solution was purified by reverse phase column chromatography (ACN:H2O = 0:100-10:90, followed by MeOH:H2O = 10:90-100:0) to obtain 210 mg of compound 8a (yield 58.85%).

[0949] MS (ESI): m / z 1167.3 [M / 2+1] + .

[0950] Step 2:

[0951] Compound 8a (220 mg, 94.28 μmol) was dissolved in DMF (5 mL), piperidine (40 μL) was added, and the reaction was carried out at room temperature for 2 h. The reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to obtain 110 mg of compound 8b (yield 55.26%).

[0952] MS (ESI): m / z 1056.2 [M / 2+1] + .

[0953] Step 3:

[0954] Compound 8b (110 mg, 52.10 μmol), trans-2,5-dioxopyrrolidin-l-yl 4-((2,5-dioxo- 2,5-dihydro-lH-pyrrol-l-yl)methyl)cyclohexanecarboxylate (23 mg, 68.80 μmol, purchased from Adamas) were dissolved in DMF (2 mL), triethylamine (25 μL, 179.37 μmol) was added, and the mixture was stirred at room temperature for 2.5 h. The reaction mixture was purified by reverse phase preparative chromatography (ACN / H20 with 0.1% HCOOH) to give 30 mg of compound 8 (yield 24.71%).

[0955] MS (ESI): m / z 1165.7 [M / 2+1]+.

[0956] Example 9 Preparation of compound 9

[0957] Step 1:

[0958] Compound Id (161 mg, 103.70 μmol), 2,5,8,11,14,17,20,23,26,29,32,35,38- tridecaoxaheptatriacontan-41-oic acid (92 mg, 145.40 μmol, purchased from Bide), DIPEA (70 μL, 401.88 μmol), HATU (72 mg, 189.36 μmol) were dissolved in DMF (2.5 mL), and the mixture was stirred at room temperature for 2.5 h. Methyl tert-butyl ether (25 mL) was added to the reaction mixture, and the mixture was stirred for 1 h and then filtered to give 240 mg of compound 9a as a crude product (yield 112.72%).

[0959] MS (ESI): m / z 1027.2 [M / 2+1] + .

[0960] Step 2:

[0961] Compound 9a (240 mg, about 103 μmol) was dissolved in DMF (3 mL), piperidine (60 μL) was added, and the mixture was stirred at room temperature for 3.5 h. The reaction mixture was purified by reverse phase preparative chromatography (ACN / H20 with 0.1% HCOOH) to give 48 mg of compound 9b (yield 25.28%).

[0962] MS (ESI): m / z 1831.7 [M+1] + .

[0963] Step 3:

[0964] Compound 9b (48 mg, 26.21 μmol), trans-2,5-dioxopyrrolidin-l-yl 4-((2,5-dioxo- 2,5-dihydro-lH-pyrrol-l-yl)methyl)cyclohexanecarboxylate (11.4 mg, 34.10 μmol, purchased from Adamas) were dissolved in DMF (2.5 mL), DIPEA (20 μL, 114.82 μmol) was added, and the mixture was stirred at room temperature for 2.5 hours. The reaction solution was purified by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH) to give 14 mg of compound 9 (yield 26.05%).

[0965] MS (ESI): m / z 1025.7 [M / 2 + 1] + .

[0966] 1 H NMR (400 MHz, DMSO-d6) δ 10.03 (s, 1H), 8.25 - 7.96 (m, 3H), 7.89 - 7.67 (m, 4H), 7.61 (d, 2H), 7.47 - 7.24 (m, 3H), 7.01 (s, 1H), 6.56 - 6.51 (m, 1H), 6.00 (s, 2H), 5.47 - 5.20 (m, 6H), 5.08 (s, 2H), 4.55 - 4.12 (m, 3H), 3.84 - 3.35 (m, 62H), 3.25 - 2.88 (m, 15H), 2.45 - 2.10 (m, 9H), 2.08 - 1.78 (m, 5H), 1.78 - 1.05 (m, 18H), 0.88 - 0.82 (m, 12H).

[0967] The following antibodies were prepared according to standard methods for antibodies, for example, after vector construction, eukaryotic cells such as HEK293 cells (Life Technologies Cat. No. 11625019) were transfected and the expressed antibodies were purified.

[0968] The sequence of Trastuzumab is as follows:

[0969] Light chain SEQ ID NO: 1

[0970] Heavy chain SEQ ID NO: 2

[0971] The sequence of Tisotumab is as follows:

[0972] Light chain SEQ ID NO: 3

[0973] Heavy chain SEQ ID NO: 4

[0974] Antibody sequences of B7H3 antibody SDP05873

[0975] Light chain SEQ ID NO: 5

[0976] Heavy chain SEQ ID NO: 6

[0977] Antibody sequences of Claudin 18.2 antibody SDP13153

[0978] Light chain SEQ ID NO: 7

[0979] Heavy chain SEQ ID NO: 8

[0980] Example 10 Preparation of ADC-1

[0981] Procedure:

[0982] Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) was added to a 2.0 mL EP tube, then TCEP (51.7 μL, 0.52 μmol, 10 mmol / L) was added, and incubated at 25 degrees for 24 hours. After removing the salt column (Zeba TM Thermo), 3.48 mg of ADC-1 (yield 69%) was obtained, and the k was 7.94 by RP-HPLC method, and stored at 4 degrees.

[0983] Example 11 Preparation of ADC-2

[0984] Procedure:

[0985] Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) was added to a 2.0 mL EP tube, then TCEP (41.4 μL, 0.061 μmol, 1.5 mmol / L) was added, and incubated at 37 degrees for 3 hours. After removing the salt column (Zeba TMThermo) to give 4.88 mg of ADC-2 (yield 98%) with k of 4.12 by RP-HPLC method, stored at 4°C.

[0986] Example 12 Preparation of ADC-3

[0987] Procedure:

[0988] To a 2.0 mL EP tube was added 5 mg of antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) followed by TCEP (51.7 μL, 0.51 μmol, 10 mmol / L) and incubated at 37°C for 3 hours. The mixture was removed and a solution of Compound 2 (1.93 mg, 0.86 μmol) in DMSO (25 μL) was added and shaken at 25°C for 3 hours. The mixture was passed through a desalting column (Zeba TM Thermo) to give 4.88 mg of ADC-2 (yield 98%) with k of 4.12 by RP-HPLC method, stored at 4°C.

[0989] Example 13 Preparation of ADC-4

[0990] Procedure:

[0991] To a 2.0 mL EP tube was added 5 mg of antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) followed by TCEP (51.7 μL, 0.51 μmol, 10 mmol / L) and incubated at 37°C for 3 hours. The mixture was removed and a solution of Compound 2 (1.93 mg, 0.86 μmol) in DMSO (25 μL) was added and shaken at 25°C for 3 hours. The mixture was passed through a desalting column (Zeba TM Thermo) to give 4.88 mg of ADC-2 (yield 98%) with k of 4.12 by RP-HPLC method, stored at 4°C.

[0992] Example 14 Preparation of ADC-5

[0993] Procedure:

[0994] To a 2.0 mL Eppendorf tube was added 5 mg of antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) followed by TCEP (51.7 μL, 0.51 μmol, 10 mmol / L) and incubated at 37°C for 3 hours. The mixture was removed and a solution of Compound 4 (1.58 mg, 0.69 μmol) in DMSO (25 μL) was added and shaken at 25°C for 3 hours. The mixture was passed through a desalting column (Zeba TM Thermo) to give 4.90 mg of ADC-5 (yield 98%) with k = 7.98 by RP-HPLC method and stored at 4°C.

[0995] Example 15 Preparation of ADC-6

[0996] Procedure:

[0997] To a 2.0 mL Eppendorf tube was added 5 mg of antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) followed by TCEP (51.7 μL, 0.51 μmol, 10 mmol / L) and incubated at 37°C for 3 hours. The mixture was removed and a solution of Compound 5 (1.64 mg, 0.69 μmol) in DMSO (25 μL) was added and shaken at 25°C for 3 hours. The mixture was passed through a desalting column (Zeba TM Thermo) to give 5.0 mg of ADC-6 (yield 100%) with k = 8.01 by RP-HPLC method and stored at 4°C.

[0998] Example 16 Preparation of ADC-7

[0999] Procedure:

[1000] To a 2.0 mL Eppendorf tube was added 5 mg of antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) followed by TCEP (51.7 μL, 0.51 μmol, 10 mmol / L) and incubated at 37°C for 3 hours. The mixture was removed and a solution of Compound 6 (1.48 mg, 0.69 μmol) in DMSO (25 μL) was added and shaken at 25°C for 3 hours. The mixture was passed through a desalting column (Zeba TM Thermo) to give 4.5 mg of ADC-7 (yield 90%) with k = 8.17 by RP-HPLC method and stored at 4°C.

[1001] Example 17 Preparation of ADC-8

[1002] Procedure:

[1003] To a 2.0 mL Eppendorf tube was added 5 mg antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) followed by TCEP (51.7 μL, 0.51 μmol, 10 mmol / L) and incubated at 37°C for 3 hours. The mixture was removed and a solution of Compound 7 (1.49 mg, 0.69 μmol) in DMSO (25 μL) was added and shaken at 25°C for 3 hours. The mixture was passed through a desalting column (Zeba TM Thermo) to give 3.2 mg of ADC-8 (yield 64%) with k = 7.65 by RP-HPLC method and stored at 4°C.

[1004] Example 18 Preparation of ADC-9

[1005] Procedure:

[1006] To a 2.0 mL Eppendorf tube was added 5 mg antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) followed by TCEP (51.7 μL, 0.51 μmol, 10 mmol / L) and incubated at 37°C for 3 hours. The mixture was removed and a solution of Compound 8 (1.61 mg, 0.69 μmol) in DMSO (25 μL) was added and shaken at 25°C for 3 hours. The mixture was passed through a desalting column (Zeba TM Thermo) to give 3.3 mg of ADC-9 (yield 66%) with k = 7.61 by RP-HPLC method and stored at 4°C.

[1007] Example 19 Preparation of ADC-10

[1008] Procedure:

[1009] To a 2.0 mL Eppendorf tube was added 5 mg antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) followed by TCEP (51.7 μL, 0.51 μmol, 10 mmol / L) and incubated at 37°C for 3 hours. The mixture was removed and a solution of Compound 9 (1.41 mg, 0.69 μmol) in DMSO (25 μL) was added and shaken at 25°C for 3 hours. The mixture was passed through a desalting column (Zeba TM Thermo) to give 4.5 mg of ADC-10 (yield 90%) with k = 7.96 by RP-HPLC method and stored at 4°C.

[1010] Preparation of compound 10 of example 20

[1011] Step 1:

[1012] Compound 10a (2.0 g, 4.90 mmol, purchased from Bide), 10b (0.66 g, 3.77 mmol, purchased from Bide) were dissolved in anhydrous DMF (40 mL), the system was protected by nitrogen, potassium carbonate (1.0 g, 7.50 mmol) was added, and the reaction was heated to 100°C. When the raw material was completely reacted, it was cooled to room temperature, the solvent was concentrated to dryness, 30 mL of water was added, and the organic phase was extracted with 30 mL of dichloromethane three times. The organic phase was washed with water and saturated sodium chloride solution, dried, filtered, concentrated, and column chromatography (petroleum ether: ethyl acetate = 3:1) to obtain compound 10c about 1.2 g (yield: 76.0%) as a light yellow oil.

[1013] MS (ESI): m / z 439.1 [M+18] + .

[1014] Step 2:

[1015] Compound 10c (1.2 g, 8.85 mmol), palladium on carbon (0.30 g, 25% w / w) were dissolved in anhydrous ethanol (60 mL), and the hydrogen gas balloon was replaced three times with hydrogen. The reaction was heated to 39°C, and when the raw material was completely reacted, it was filtered with diatomite, washed with 300 mL of ethanol, concentrated, and column chromatography (petroleum ether: ethyl acetate = 2:1) to obtain compound 10d about 1.0 g (yield: 89.7%) as a light yellow oil.

[1016] MS (ESI): m / z 409.2 [M+18] + .

[1017] Step 3:

[1018] Compound 10d (0.40 g, 1.02 mmol) was dissolved in acetic acid (6 mL), the system was protected by nitrogen, 10e (262 mg, 1.02 mmol) was added, and the reaction was heated to 110°C. When the raw material was completely reacted, it was cooled to room temperature, concentrated, and the solid was pumped dry to obtain compound 10f about 0.60 g, which was directly used in the next step reaction.

[1019] MS (ESI): m / z 571.9 [M+1] + .

[1020] Step 4:

[1021] Compound 10f (0.60 g, 1.02 mmol) was dissolved in anhydrous dichloromethane (10 mL), and 8 g (0.79 g, 3.06 mmol) of a dichloromethane (20 mL) solution was added. The system was protected by nitrogen, and cooled to 0°C. DIPEA (0.40 g, 3.06 mmol) was added dropwise. The reaction was performed at 0°C. When the reaction was completed, column chromatography (dichloromethane:methanol = 10:1 ~ 6:1) was performed to obtain about 0.10 g of compound 10h (two-step yield: 10%).

[1022] MS (ESI): m / z 926.2 [M+1] + .

[1023] Step 5:

[1024] Compound 10i (1.0 g, 3.26 mmol), 10j (1.19 g, 9.79 mmol) was dissolved in anhydrous DCM (10 mL), and the system was protected by nitrogen. DIPEA (2.11 g, 16.32 mmol), HATU (3.73 g, 9.79 mmol) were added. The reaction was performed at room temperature. When the reaction was completed, 20 mL of water was added and stirred. 30 mL of dichloromethane was extracted three times. The organic phase was washed with water three times, and saturated sodium chloride solution once. Anhydrous sodium sulfate was dried, filtered, concentrated, and reverse phase column chromatography (acetonitrile: water) was performed. Compound 10k was obtained as a light yellow solid in about 1 g (yield: 60%) after lyophilization.

[1025] MS (ESI): m / z 513.1 [M+1] + .

[1026] Step 6:

[1027] Compound 10k (0.79 g, 1.54 mmol) was dissolved in anhydrous ethanol (10 mL) and anhydrous tetrahydrofuran (10 mL). The system was protected by nitrogen and cooled to 0°C. Sodium borohydride (176 mg, 4.62 mmol) was added. The reaction was performed at room temperature. When the reaction was completed, 1 mL of water and 30 mL of ethyl acetate were added and stirred. Saturated ammonium chloride solution was added until the solution was clear. Only water was concentrated, 10 mL of water and 30 mL of ethyl acetate were added and stirred. 30 mL of ethyl acetate was extracted three times. The organic phase was washed with saturated sodium chloride solution, dried, filtered, and concentrated to obtain about 0.79 g of compound 10g, which was directly used in the next reaction.

[1028] MS (ESI): m / z 258.1 [M+1] + .

[1029] Step 7:

[1030] Compound 10l (0.2 g, 0.17 mmol, prepared by the known method “WO2023 / 280227”), compound 2c (0.166 g, 0.20 mmol) were dissolved in anhydrous DMF (4 mL), the system was protected by nitrogen, DIPEA (66 mg, 0.50 mmol), HATU (96 mg, 0.25 mmol) were added, the reaction was carried out at room temperature, and the reaction was complete after the control of raw materials. MTBE 24 mL was added to the system and stirred for 10 min, the supernatant was filtered, and then MTBE 10 mL was added to the system and stirred for 10 min, the supernatant was filtered, and the solid was collected and dried by oil pump. Compound 10m about 0.33 g was obtained, which was directly used in the next step reaction.

[1031] MS (ESI): m / z 998.2 [M / 2+1] + .

[1032] Step 8:

[1033] Compound 10m (0.33 g, 0.17 mmol) was dissolved in anhydrous DMF (4 mL), the system was protected by nitrogen, piperidine (72 mg, 0.83 mmol) was added, the reaction was carried out at room temperature, and the reaction was complete after the control of raw materials. Purification was performed by reverse phase preparative chromatography (ACN / H2O with 0.1% HCOOH), and freeze-drying was performed to obtain compound 10n about 0.1 g (two-step yield: 33.6%).

[1034] MS (ESI): m / z 1773.7 [M+1] + .

[1035] Step 9:

[1036] Compound 10n (30 mg, 16.92 μmol), compound 10h (16 mg, 16.92 μmol) were dissolved in anhydrous DMF (4 mL), the system was protected by nitrogen, DIPEA (7 mg, 50.76 μmol), HATU (10 mg, 25.39 μmol) were added, the reaction was carried out at room temperature, and the reaction was complete after the control of raw materials. Purification was performed by reverse phase preparative chromatography (ACN / H2O with 0.1% CF3COOH), and freeze-drying was performed to obtain compound 10 about 20 mg of yellow solid, purity 99.3%, (yield: 44.0%).

[1037] MS (ESI): m / z 1340.7 [M / 2+1] + .

[1038] 1H NMR (400 MHz, DMSO) δ 10.04 (s, 1H), 8.14 (d, 1H), 8.06 (d, 1H), 7.90 (d, 1H), 7.83-7.76 (m, 2H), 7.67 (d, 1H), 7.60 (d, 2H), 7.37-7.29 (m, 11H), 7.26-7.20 (m, 2H), 5.99 (s, 1H), 5.45 (s, 3H), 5.37-5.23 (m, 5H), 5.08 (s, 3H), 4.42-4.15 (m, 15H), 4.10-3.90 (m, 13H), 3.77-3.19 (m, 37H), 3.03-2.67 (m, 22H), 2.43-2.14 (m, 7H), 2.11-1.74 (m, 15H), 1.71-1.33 (m, 9H), 0.93-0.76 (m, 9H).

[1039] Preparation of compound 11 of Example 21

[1040] Step 1:

[1041] Compound 2b (0.53 g, 0.262 mmol, 1.0 eq), 11a (70.38 mg, 0.262 mmol, 1.0 eq, purchased from econcen) were added into a 25 mL flask, stirred and dissolved at room temperature in 4 mL of anhydrous DMF, and the system was protected by nitrogen. After the addition of HATU (0.12 g, 0.315 mmol, 1.2 eq) and DIPEA (0.10 g, 0.787 mmol, 3.0 eq) at room temperature, the reaction was allowed to proceed for 1 hour. The reaction solution was directly sent to HPLC preparation (acetonitrile / water / formic acid system) to collect the positive component phase. After the acetonitrile was concentrated, 270 mg of white solid compound 11 was obtained by freeze-drying, with a purity of 99% and a yield of 45%.

[1042] MS (ESI): m / z 1135.7 [M / 2+1] + .

[1043] 1H NMR (400 MHz, DMSO): δ 10.02 (s, 1H), 9.11 (s, 2H), 8.11 (d, 1H), 8.07-8.01 (m, 2H), 7.94-7.91 (m, 1H), 7.80-7.77 (m, 2H), 7.71-7.69 (m, 1H), 7.61-7.59 (m, 2H), 7.37-7.35 (m, 2H), 7.31 (s, 1H), 6.52 (s, 1H), 5.98 (t, 1H), 5.45 (s, 2H), 5.42 (s, 2H), 5.34-5.24 (m, 4H), 5.08 (s, 2H), 4.40-4.17 (m, 9H), 4.13-3.88 (m, 7H), 3.60-3.55 (m, 4H), 3.49-3.38 (m, 46H), 3.22-2.68 (m, 29H), 2.54 (t, 2H), 2.41-1.28 (m, 20H), 0.89-0.81 (m, 9H).

[1044] Preparation of compound 12 of Example 22

[1045] Step 1:

[1046] Compound 10n (0.95 g, 0.54 mmol, 1.0 eq), Fmoc amino hexanoic acid (0.19 g, 0.54 mmol, 1.0 eq) were added into a 50 mL flask, 10 mL anhydrous DMF was added under room temperature and stirred to dissolve, the system was protected by nitrogen, HATU (0.25 g, 0.65 mmol, 1.2 eq), DIPEA (0.35 g, 2.68 mmol, 3.0 eq) were added, the reaction was controlled under room temperature, when the raw material was completely reacted, the reaction solution was directly loaded onto a 120 g C18 reversed-phase column (0.1% TFA water: methanol system), the positive component phase was collected, concentrated, and freeze-dried to obtain about 1.0 g of compound 12a with a yield of 88%.

[1047] MS (ESI): m / z 1055.1 [M / 2+1] + .

[1048] Step 2:

[1049] Compound 12a (89 mg, 42.2 mmol, 1.0 eq) was added to a 20 mL flask, stirred and dissolved in 2 mL of anhydrous DMF at room temperature, the system was protected by nitrogen, piperidine (20.3 mg, 253.3 ummol, 6.0 eq) was added at room temperature, the reaction was controlled by the amount of raw material, the reaction liquid was directly sampled on a 40 g C18 reverse phase column (0.1% TFA water: acetonitrile system), the positive component phase was collected, concentrated, and freeze-dried to obtain about 70 mg of compound 12b, yield: 88%.

[1050] MS (ESI): m / z 1885.9 [M+1] + .

[1051] Step 3:

[1052] Bromine acetic acid (18.4 mg, 74.2 umol, 2.0 eq), EEDQ (18.4 mg, 74.2 umol, 2.0 eq) were added to a 20 mL flask, 2 mL of anhydrous DMF was added and stirred and dissolved, the system was protected by nitrogen, compound 12b (70 mg, 37.1 umol, 1.0 eq) was dissolved in 3 mL of anhydrous DMF and added dropwise to the reaction system, after addition, the reaction was carried out at room temperature, the reaction was controlled by the amount of raw material, LCMS: a small amount of raw material was left, the reaction liquid was directly sent to analytical HPLC preparation (acetonitrile / water / formic acid system), the positive component phase was collected, and freeze-dried to obtain about 18 mg of compound 12 as a white solid, yield: 24%.

[1053] MS (ESI): m / z 1004.7 [M / 2+1] + .

[1054] 1 H NMR (400 MHz, DMSO): δ 10.03 (s, 1H), 8.26-8.22 (m, 1H), 8.12 (d, 1H), 8.06 (d, 1H), 7.97 (d, 1H), 7.82-7.78 (m, 2H), 7.66 (d, 1H), 7.61 (d, 2H), 7.37 (d, 2H), 7.32 (s, 1H), 6.00-5.97 (m, 1H), 5.46-5.43 (m, 4H), 5.34-5.30 (m, 4H), 5.08 (s, 2H), 4.41-4.32 (m, 4H), 4.28-4.18 (m, 6H), 4.13-3.89 (m, 8H), 3.82 (s, 2H), 3.59-3.39 (m, 32H), 3.05-2.67 (m, 18H), 2.39 (s, 3H), 2.34 (s, 3H), 2.29 (t, 2H), 2.23-2.10 (m, 4H), 2.03-1.36 (m, 19H), 0.90-0.82 (m, 9H).

[1055] Preparation of compound 13 of Example 23

[1056] Step 1:

[1057] Compound 13a (300 mg, 820.97 μmol, purchased from Bide) and compound 12b-1 (169.12 mg, 903.07 μmol, purchased from Aikang) were dissolved in DCM (3 mL) and stirred at room temperature. DIPEA (318.31 mg, 2.46 mmol, 428.99 μL) and HATU (468.24 mg, 1.23 mmol) were added successively, and the reaction was carried out at room temperature. When the raw material was completely consumed, the reaction solution was concentrated to dryness. Purification by column (DCM:MeOH = 100:0-90:10) gave 397.2 mg of compound 13b (yield 90.49%).

[1058] MS (ESI): m / z 535.3 [M+1] + .

[1059] Step 2:

[1060] Compound 13b (150 mg, 280.54 μmol) was dissolved in DCM (1.5 mL) and stirred at room temperature. After the addition of TFA (1.14 g, 9.99 mmol, 769.67 μL), the reaction was carried out at room temperature. When the raw material was completely consumed, the reaction solution was concentrated to dryness to give a crude oil. The crude product was washed with MTBE (3 mL) for 30 minutes, filtered, and the filter cake was washed with MTBE and dried to give 135.7 mg of a solid crude compound 13c (yield 101.07%). The crude product was directly used in the next step.

[1061] MS (ESI): m / z 479.3 [M+1] + .

[1062] Step 3:

[1063] Compound 13c (118.77 mg, 248.17 μmol) and 10n (400.00 mg, 225.61 μmol) were dissolved in DMF (4 mL) and stirred at room temperature. DIPEA (87.48 mg, 676.83 μmol, 117.89 μL) and HATU (111.52 mg, 293.29 μmol) were added successively. After the addition was complete, the reaction was carried out at room temperature. When the raw material was completely consumed, the reaction solution was directly purified by reverse phase column (H2O (0.1% TFA):MeOH = 100:0-0:100) to give 304.9 mg of compound 13d (yield 60.51%).

[1064] MS (ESI): m / z 1117.8 [M / 2+1] + .

[1065] Step 4:

[1066] Compound 13d (250 mg, 111.932 pmol) was dissolved in DMF (3.5 mL) and stirred at room temperature 20 degree. After adding DEA (409.31 mg, 5.60 mmol, 579.76 pL) at room temperature 20 degree, the reaction was carried out for 1 hour. MTBE (3 mL) was slowly added to the reaction solution, and solids were precipitated. The beating was continued for 30 minutes. After filtration, the filter cake was rinsed with MTBE and dried to obtain 190 mg of crude compound 13e (yield 84.40%). The crude product was directly used in the next step reaction.

[1067] MS (ESI): m / z 1006.5 [M / 2+1] + .

[1068] Step 5:

[1069] Compound 12g-1 (34.05 mg, 245.04 pmol, purchased from adamas) was dissolved in DMF (3.8 mL) and stirred at room temperature 20 degree. After adding EEDQ (60.60 mg, 245.04 pmol) at room temperature 20 degree, the reaction was carried out for 1 hour. After adding compound 13e (190 mg, 122.52 pmol) at room temperature 20 degree, the reaction was carried out until the raw material was completely reacted. After preparation, 30.1 mg of compound 13 was obtained by freeze-drying (yield 11.52%).

[1070] MS (ESI): m / z 1067.3 [M / 2+1] + .

[1071] 1H NMR (400 MHz, DMSO) δ 10.02 (s, 1H), 8.19-8.10 (m, 2H), 8.08-8.01 (m, 1H), 8.00-7.88 (m, 1H), 7.84-7.72 (m, 2H), 7.71-7.53 (m, 4H), 7.36 (d, J = 8.2 Hz, 2H), 7.31 (s, 1H), 6.52 (s, 1H), 5.98 (s, 1H), 5.43 (d, J = 12.8 Hz, 4H), 5.29 (s, 3H), 5.08 (s, 2H), 4.44-4.29 (m, 3H), 4.29-4.15 (m, 5H), 4.15-3.83 (m, 6H), 3.78 (s, 2H), 3.57 (t, J = 6.6 Hz, 2H), 3.54-3.36 (m, 22H), 3.25-3.17 (m, 3H), 3.08-2.65 (m, 23H), 2.38 (s, 4H), 2.33 (s, 1H), 2.28 (t, J = 6.5 Hz, 3H), 2.44-2.05 (m, 4H), 2.06-1.54 (m, 15H), 1.53-1.05 (m, 18H), 0.94-0.74 (m, 9H).

[1072] Example 24 Preparation of ADC-11

[1073] Procedure:

[1074] Trastuzumab (5 mg, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) was added to a 2.0 mL EP tube, followed by TCEP (33.6 μL, 0.34 μmol, 10 mmol / L), incubated at 37°C for 3 hours, removed, ultrafiltration exchanged 4-5 times, added compound 10 (0.90 mg, 0.34 μmol) in DMSO (10 μL), oscillated at 25°C for 3 hours. Purified by AKTA Purifier-10 (GE Healthcare) on Superdex 200 26 / 600 SEC (GE Healthcare) column to get 4.0 mg ADC-11 (yield 80%), purity 98.6% by SEC, k 3.80 by mass spectrometry, stored at 4°C.

[1075] Example 25 Preparation of ADC-12

[1076] Procedure:

[1077] Into a 2.0 mL EP tube, 5 mg antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) was added, followed by TCEP (33.6 μL, 0.34 μmol, 10 mmol / L), incubated at 37°C for 3 hours, removed, ultrafiltration exchanged 4-5 times, added compound 11 (1.52 mg, 0.68 μmol) in DMSO (25 μL), oscillated at 25°C for 3 hours. Purified by AKTA Purifier-10 (GE Healthcare) with Super dex200 26 / 600 SEC (GE Healthcare) column to get 4.05 mg ADC-12 (yield 81%), purity 98.5% by SEC, k 7.85 by RP-HPLC, stored at 4°C.

[1078] Example 26 Preparation of ADC-13

[1079] Procedure:

[1080] Into a 2.0 mL EP tube, 5 mg antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) was added, followed by TCEP (33.6 μL, 0.34 μmol, 10 mmol / L), incubated at 37°C for 3 hours, removed, ultrafiltration exchanged 4-5 times, added compound 12 (1.35 mg, 0.68 μmol) in DMSO (25 μL), oscillated at 25°C for 3 hours. Purified by AKTA Purifier-10 (GE Healthcare) with Super dex200 26 / 600 SEC (GE Healthcare) column to get 4.50 mg ADC-13 (yield 90%), purity 98.8% by SEC, k 7.89 by RP-HPLC, stored at 4°C.

[1081] Example 27 Preparation of compound 14

[1082] Procedure 1:

[1083] Compound 14a (2.0 g, 3.00 mmol, 1.0 eq, prepared by using the known method “WO2024222960A1”) and 5 mL of anhydrous DCM were added to a 50 mL flask, piperidine (766 mg, 9.00 mmol, 3.0 eq) was added, the system was protected by nitrogen, and the reaction was carried out at room temperature for 1 h; the reaction solution was added to 20 mL of water and 20 mL of DCM, the liquid was separated, the aqueous phase was extracted twice with DCM, and the aqueous phase was freeze-dried to obtain 990 mg of compound 14b in the form of colorless oil with a yield of 74%.

[1084] MS (ESI): m / z 445.3 [M+1] + .

[1085] Step 2:

[1086] Compound 14b (860.0 mg, 1.93 mmol, 1.0 eq) and 14c (1.80 g, 3.87 mmol, 2.0 eq, prepared by using the known method “US2006 / 18874, 2006, A1”) were added to a 100 mL flask, 10 mL of anhydrous DMF was added under stirring and dissolution at room temperature, the system was protected by nitrogen, triethylamine (587.4 mg, 5.80 mmol, 3.0 eq) was added, and the reaction was carried out at room temperature for 1 h; the reaction solution was directly loaded onto a C18 reverse phase column (water: acetonitrile system) for column purification, the positive component phase was collected, concentrated, and freeze-dried to obtain 890 mg of compound 14d with a yield of 58%.

[1087] MS (ESI): m / z 795.6 [M+1] + .

[1088] Step 3:

[1089] Compound 14d (650.0 mg, 0.82 mmol, 1.0 eq) and 14e (363.9 mg, 0.82 mmol, 1.0 eq, purchased from Bide Pharmaceutical) were added to a 100 mL flask, 13 mL of anhydrous acetonitrile was added under stirring and dissolution at room temperature, the system was protected by nitrogen, TCFH (413.0 mg, 1.47 mmol, 1.8 eq) and N-methyl imidazole (302.1 mg, 3.68 mmol, 4.5 eq) were added, and the reaction was carried out at room temperature for 1 h; the reaction system was rotary dried, loaded onto a C18 reverse phase column (0.1% TFA water: acetonitrile system) for column purification, the positive component phase was collected, concentrated, and freeze-dried to obtain 550 mg of compound 14f with a yield of 57%.

[1090] MS (ESI): m / z 1185.6 [M+1] + .

[1091] Step 4:

[1092] Compound 14f (675 mg, 569.45 μmol) was dissolved in acetonitrile (7 mL), diethylamine (350 mg, 4.79 mmol, 8.4 eq) was added, and the mixture was stirred at room temperature for 2.5 hours. The reaction solution was concentrated, the residue was dissolved in 10 mL of acetonitrile, and the operation was repeated 5 times. An oil pump was used to dry the residue to obtain 729 mg of white solid compound 14g, with a yield of 133%.

[1093] MS (ESI): m / z 963.7 [M+1] + .

[1094] Step 5:

[1095] Fmoc-NH-PEG4-acid (298 mg, 611.23 μmol, 1.07 eq) was dissolved in DMF (7 mL), and compound 14g (548 mg, 568.98 μmol) was added. To the mixture, HATU (322 mg, 846.86 μmol, 1.5 eq) and DIPEA (0.3 mL, 1.72 mmol, 3 eq) were added. The mixture was stirred at room temperature for 1 hour. 10 mL of water was added to the reaction solution, and the mixture was extracted with ethyl acetate (10 mL*3). The ethyl acetate extract was discarded. The water layer was extracted with DCM / MeOH=10 mL / 5 mL once and 10 mL / 2 mL twice. The water layer was discarded, and the organic extract was combined and concentrated. The residue was dissolved in 10 mL of water and freeze-dried to obtain 818 mg of yellow oil compound 14h with a yield of 100%.

[1096] MS (ESI): m / z 1432.7 [M+1] + .

[1097] Step 6:

[1098] Compound 14h (818 mg, 570.97 μmol) was dissolved in DMF (6 mL), and thiosalicylic acid (438 mg, 2.84 mmol, 5 eq) and tetrakis triphenylphosphine palladium (192 mg, 166.15 μmol, 0.3 eq) were added. The mixture was stirred at room temperature for 3.5 hours. 10 mL of water was added to quench the reaction, and the mixture was filtered through diatomite. The filtrate was extracted with ethyl acetate (10 mL*3). The organic layer was discarded, and the water layer was freeze-dried to obtain 725 mg of yellow oil compound 14i with a yield of 91.2%.

[1099] MS (ESI): m / z 1392.6 [M+1] + .

[1100] Step 7:

[1101] Compound 14i (725 mg, 520.62 pmol), compound 14j (442 mg, 525.63 pmol, 1 eq, prepared by the known method “WO2022 / 58395, 2022, Al”) were dissolved in DMF (5 mL), HATU (390 mg, 1.03 mmol, 2 eq), DIPEA (290 mg, 2.24 mmol, 4.3 eq) were added under ice water bath. The reaction was stirred for 1 h under ice water bath. The reaction mixture was directly loaded on C18 reverse phase column (0.1% TFA water: methanol system), the positive component phase was collected, concentrated, and lyophilized to get yellow solid 767 mg of compound 14k, yield: 66.5%.

[1102] MS (ESI): m / z 1108.7 [M / 2+1] + .

[1103] Step 8:

[1104] Compound 14k (222 mg, 100.20 pmol) was dissolved in DMF (1.5 mL), piperidine (50 pL, 506.18 pmol, 5 eq) was added, and stirred at room temperature for 2.5 h. The reaction mixture was directly loaded on C18 reverse phase column (0.1% TFA water: methanol system), the positive component phase was collected, concentrated, and lyophilized to get yellow solid 230 mg of compound 141, yield: 109%.

[1105] MS (ESI): m / z 1993.0 [M+1] + .

[1106] Step 9:

[1107] Compound 141 (210 mg, 99.66 pmol) was dissolved in DMF (2.5 mL), trans-4-maleimidomethyl cyclohexane carboxy-azahydroxysuccinimide (38 mg, 113.66 pmol, 1.1 eq), TEA (56 pL, 401.78 pmol, 4 eq) were added, and stirred at room temperature for 3 h. The reaction mixture was directly sent for analytical HPLC preparation (acetonitrile / water / formic acid system), the positive component phase was collected, and lyophilized to get white solid 70 mg of compound 14, yield: 31.7%.

[1108] MS (ESI): m / z 1107.1 [M / 2+1] + .

[1109] 1H NMR (400 MHz, DMSO): δ 10.02 (s, 1H), 8.12-8.02 (m, 3H), 7.78 (d, 1H), 7.73-7.70 (m, 2H), 7.60 (d, 2H), 7.36 (d, 2H), 7.31 (s, 1H), 7.00 (s, 2H), 6.52 (s, 1H), 5.98 (t, 1H), 5.45 (s, 2H), 5.42 (s, 2H), 5.29 (s, 3H), 5.07 (s, 2H), 4.40-4.19 (m, 8H), 4.08-3.87 (m, 6H), 3.62-3.55 (m, 4H), 3.50-3.47 (m, 32H), 3.43-3.35 (m, 5H), 3.24-3.22 (m, 6H), 3.15-2.67 (m, 27H), 2.42-2.32 (m, 7H), 2.25-2.07 (m, 2H), 2.06-1.82 (m, 4H), 1.69-1.56 (m, 7H), 1.55-1.33 (m, 6H), 1.31-1.19 (m, 5H), 0.88-0.83 (m, 11H).

[1110] Preparation of compound 15 of example 28

[1111] Step 1:

[1112] Compound 15a (300 mg, 790.62 μmol, purchased from Bide) and compound 12b-1 (162.87 mg, 869.68 μmol, purchased from Aikang) were dissolved in DCM (3 mL) and stirred at room temperature. DIPEA (306.55 mg, 2.37 mmol, 413.14 μL) and HATU (450.93 mg, 1.19 mmol) were added successively, and the reaction was allowed to proceed at room temperature for 1 hour. The reaction solution was concentrated to dryness. Purification by column (DCM:MeOH = 100:0-90:10) gave 384.5 mg of compound 15c (yield 88.63%).

[1113] MS (ESI): m / z 549.3 [M+1] + .

[1114] Step 2:

[1115] Compound 15c (150 mg, 273.37 pmol) was dissolved in DCM (1.5 mL) and stirred at room temperature. After the addition of TFA (1.11 g, 9.73 mmol, 750.00 pL), the reaction was allowed to react at room temperature for 2 hours. The reaction solution was concentrated to dryness to obtain a crude oil. The crude product was slurried in MTBE (3 mL) for 30 minutes, filtered, and the filter cake was rinsed with MTBE and dried to obtain 136.2 mg of crude solid compound 15d (yield 101.14%). The crude product was directly used in the next step.

[1116] MS (ESI): m / z 493.3 [M+1] + .

[1117] Step 3:

[1118] Compound 15d (91.69 mg, 186.13 pmol) and 10n (300.00 mg, 169.21 pmol) were dissolved in DMF (4 mL) and stirred at room temperature. DIPEA (65.61 mg, 507.63 pmol, 88.42 pL) and HATU (83.64 mg, 219.97 pmol) were added sequentially. After the addition was complete, the reaction was allowed to react at room temperature for 1 hour. The reaction solution was directly passed through a reverse phase column (H2O (0.1% TFA): MeOH = 100:0-0:100) to obtain 277 mg of compound 15e (yield 72.84%).

[1119] MS (ESI): m / z 1124.5 [M / 2+1] + .

[1120] Step 4:

[1121] Compound 15e (277 mg, 123.25 pmol) was dissolved in DMF (3.6 mL) and stirred at room temperature. After the addition of DEA (405.62 mg, 5.55 mmol, 574.53 pL), the reaction was allowed to react at room temperature for 1 hour. MTBE (3 mL) was slowly added to the reaction solution, and a solid precipitated. The slurry was continued for 30 minutes. The solid was filtered, rinsed with MTBE, and dried to obtain 259.8 mg of crude compound 15f (yield 104.08%). The crude product was directly used in the next step.

[1122] MS (ESI): m / z 1013.3 [M / 2+1] + .

[1123] Step 5:

[1124] Compound 12g-1 (49.19 mg, 354.04 μmol, purchased from adamas) was dissolved in DMF (5 mL) and stirred at room temperature. After the addition of EEDQ (87.55 mg, 354.04 μmol), the reaction was carried out at room temperature for 1 hour. After the addition of compound 15f (277 mg, 177.02 μmol), the reaction was carried out at room temperature for 2.5 hours. After preparation, 48.3 mg of compound 15 (yield 12.71%) was obtained by lyophilization.

[1125] MS (ESI): m / z 1074.3 [M / 2 + 1] + .

[1126] 1H NMR (400 MHz, DMSO) δ 10.02 (s, 1H), 8.26-8.22 (m, 1H), 8.17-8.09 (m, 1H), 8.08-8.01 (m, 1H), 7.98-7.91 (m, 1H), 7.85-7.74 (m, 2H), 7.71-7.55 (m, 4H), 7.36 (d, J = 8.1 Hz, 2H), 7.31 (s, 1H), 6.52 (s, 1H), 5.98 (s, 1H), 5.43 (d, J = 13.3 Hz, 4H), 5.30 (s, 3H), 5.08 (s, 2H), 4.45-4.15 (m, 11H), 4.16-3.86 (m, 9H), 3.83 (s, 3H), 3.57 (t, J = 6.6 Hz, 4H), 3.49 (d, J = 4.1 Hz, 22H), 3.10-2.63 (m, 31H), 2.38 (s, 1H), 2.34 (s, 1H), 2.28 (t, J = 6.6 Hz, 1H), 2.24-2.06 (m, 2H), 2.05-1.94 (m, 3H), 1.93-1.80 (m, 2H), 1.78-1.55 (m, 8H), 1.52-1.14 (m, 15H), 0.96-0.72 (m, 9H).

[1127] Preparation of compound 16 of example 29

[1128] Step: compound 16

[1129] Compound 10a trifluoroacetate salt (120 mg, 0.14 mmol, prepared using a known method “WO2023083919A1 specification example 7, preparation”) was dissolved in dry N,N-dimethylformamide (3 mL), compound 10b (104 mg, 0.17 mmol, purchased from Leu-Cell, batch number L634448), N,N-diisopropyl ethylamine (55 mg, 0.42 mmol) were added sequentially under ice water bath, the reaction was stirred under ice water bath until the reaction was complete. The reaction was added to formic acid to adjust the pH value to 3-4, purified by reverse phase preparative chromatography (50-60% acetonitrile / 0.1 formic acid aqueous solution), freeze-dried to obtain 85 mg of compound 16 (yield: 48.3%).

[1130] MS (ESI): m / z 1258.3 [M+1] + .

[1131] 1 H NMR (400 MHz, DMSO-d6) δ 9.92 (s, 1H), 8.17 (d, 1H), 8.05 (d, 1H), 7.87 (d, 1H), 7.77 (d, 1H), 7.60 (d, 2H), 7.36 (d, 2H), 7.31 (d, 1H), 7.02 (s, 1H), 6.52 (s, 1H), 5.45 (s, 2H), 5.29 (s, 3H), 5.08 (s, 2H), 4.39 (t, 1H), 4.21 (t, 1H), 3.61-3.46 (m, 36H), 2.47-2.34 (m, 5H), 2.22-2.15 (m, 2H), 2.01-1.84 (m, 4H), 1.30 (d, 3H), 0.90-0.83 (m, 9H).

[1132] Preparation of compound 17 of example 30

[1133] Step 1:

[1134] Compound 7i (1.8 g, 0.93 mmol, 1.0 eq), 11a (274 mg, 1.02 mmol, 1.1 eq) were added into a 50 mL flask, stirred and dissolved in 20 mL anhydrous DMF under ice water bath, the system was protected by nitrogen, after adding HATU (0.495 g, 1.3 mmol, 1.4 eq), DIPEA (0.61 g, 4.65 mmol, 5.0 eq), the reaction was carried out at 0-15°C for 1 hour, the post-processing was carried out: the system was added into 200 mL methyl tert-butyl ether, and the slurry was carried out for 30 min, then filtered to obtain about 1.5 g of solid, 300 mg of solid was collected by HPLC preparation (acetonitrile / water formic acid system), the positive component phase was collected, and after the acetonitrile was concentrated, the freeze-drying was carried out to obtain 180 mg of white solid compound 17, the purity was 97.5%, and the yield was 74%.

[1135] MS (ESI): m / z 1093.1 [M / 2+1] + .

[1136] 1 H NMR (400 MHz, DMSO): δ 10.02 (s, 1H), 9.11 (s, 2H), 8.18-7.30 (m, 14H), 6.52 (s, 1H), 5.09-5.45 (m, 8H), 4.33-3.92 (m, 19H), 3.20-3.60 (m, 43H), 2.77-2.94 (m, 21H), 2.00-3.38 (m, 11H), 1.23-1.90 (m, 18H), 0.89-0.81 (m, 9H).

[1137] Example 31 Preparation of ADC-14

[1138] Step:

[1139] Antibody 5 mg Trastuzumab (137.3 μL, 0.034 μmol, 36.4 mg / mL, 1xPBS 7.2) and PBS 7.2 (112.7 uL) were added into a 2.0 mL EP tube, then TCEP (33.6 μL, 0.34 μmol, 10 mmol / L) was added, and the mixture was incubated at 37°C for 3 hours, taken out, and ultrafiltration was carried out for 4-5 times to obtain an intermediate solution with a concentration of 10 mg / mL, then a DMSO (25 μL) solution of compound 14 (1.11 mg, 0.68 μmol) was added, and the mixture was shaken at 25°C for 2 hours. Purification was carried out by a Protein A column (A phase: 1xPBS 7.2, B phase: 1xPBS 3.6) to obtain 3.6 mg of ADC-14 (yield 72%), the purity was 99.0% determined by SEC, the k was 8.20 determined by RP-HPLC method, and the mixture was stored at 4°C.

[1140] Preparation of ADC-15

[1141] Procedure:

[1142] To a 2.0 mL EP tube was added 5 mg antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) and PBS 7.2 (102.1 uL), followed by TCEP (33.6 μL, 0.34 μmol, 10 mmol / L). The mixture was incubated at 37 °C for 3 h, removed and buffer exchanged 4-5 times by ultrafiltration. The intermediate was formulated into a 10 mg / mL reaction solution, to which was added a DMSO (20 μL) solution of Compound 15 (1.44 mg, 0.68 μmol) and 0.5 M Tris pH 8.3 buffer (70 uL). The mixture was shaken at 25 °C for 2 h. Purification was performed on an AKTA Purifier-10 (GE Healthcare) with a Superdex 200 26 / 600 SEC (GE Healthcare) column to give 4.2 mg of ADC-15 (84% yield) with a purity of 99.0% by SEC and a k of 7.61 by RP-HPLC. The sample was stored at 4 °C.

[1143] Preparation of ADC-16

[1144] Procedure:

[1145] To a 2.0 mL EP tube was added 5 mg antibody Trastuzumab (147.9 μL, 0.034 μmol, 33.8 mg / mL, lx PBS 7.2) and PBS 7.2 (102.1 uL), followed by TCEP (33.6 μL, 0.34 μmol, 10 mmol / L). The mixture was incubated at 37 °C for 3 h, removed and buffer exchanged 4-5 times by ultrafiltration. The intermediate was formulated into a 10 mg / mL reaction solution, to which was added a DMSO (20 μL) solution of Compound 13 (1.43 mg, 0.68 μmol) and 0.5 M Tris pH 8.3 buffer (70 uL). The mixture was shaken at 25 °C for 2 h. Purification was performed on an AKTA Purifier-10 (GE Healthcare) with a Superdex 200 26 / 600 SEC (GE Healthcare) column to give 4.5 mg of ADC-16 (90% yield) with a purity of 98.8% by SEC and a k of 7.78 by RP-HPLC. The sample was stored at 4 °C.

[1146] Preparation of ADC-17

[1147] Step:

[1148] Antibody 10 mg Trastuzumab (386.1 μL, 0.067 μmol, 25.9 mg / mL, 1 x PBS 7.2) and PBS 7.2 (113.9 uL) were added to a 2.0 mL EP tube, then TCEP (67.1 μL, 0.67 μmol, 20 mmol / L) was added, and incubated at 37 degrees for 3 hours, removed, ultrafiltration exchanged 4-5 times, and obtained an intermediate solution of 10 mg / mL, then added a DMSO (50 μL) solution of compound 17 (2.2 mg, 1.00 μmol), and oscillated at 25 degrees for 2 hours. Purified by a Protein A column (A phase: 1 x PBS 7.2, B phase: 1 x PBS 3.6) to obtain 7.2 mg of ADC-17 (yield 72%), and the purity was 99.1% by SEC, and the k was 7.91 by RP-HPLC method, and stored at 4 degrees C.

[1149] Example 35 Preparation of compound 18

[1150] Step 1:

[1151] Compound 14e (5.463 g, 12.28 mmol) and compound 2c (10.3 g, 12.53 mmol) were dissolved in anhydrous acetonitrile (100 mL), and the system was protected by nitrogen, and TCFH (6.212 g, 22.14 mmol) and NMI (4.41 g, 53.71 mmol) were sequentially added at room temperature, and after the addition was completed, the reaction was carried out at room temperature for 30 min, and the reaction was complete, and the reaction liquid was concentrated to obtain a crude product of about 29.7 g, which was purified by a reversed-phase column (ACN / H2O system, 35% acetonitrile), concentrated, and freeze-dried to obtain 11.313 g of compound 18a (yield: 74.46%).

[1152] MS (ESI): m / z 1212.5 [M+1] + .

[1153] Step 2:

[1154] Compound 18a (11.31 g, 9.33 mmol) was dissolved in anhydrous acetonitrile (7.8 mL), and diethylamine (5.45 g, 74.63 mmol) was added under an ice water bath, and after the addition was completed, the ice water bath was removed, and stirred at room temperature for 1 hour. The reaction was complete, and the reaction liquid was concentrated to obtain 11.45 g of compound 18b crude product.

[1155] MS (ESI): m / z 990.6 [M+1] + .

[1156] Step 3:

[1157] Compound 18b (3.17 g, 3.20 mmol), fluorenylmethoxycarbonyl-6- aminohexanoic acid (1.137 g, 3.22 mmol, purchased from Shanghai Hao Hong Biological) were dissolved in anhydrous DMF (20 mL), and the system was protected by nitrogen. HATU (1.834 g, 4.82 mmol) and DIPEA (1.286 g, 9.95 mmol) were added in turn. After 30 min of reaction at room temperature, the reaction was complete. The reaction solution was quenched by adding water (60 mL), diluted with EA (50 mL), separated, and the aqueous phase was extracted with EA (50 mL x 3). The organic phase was discarded. The aqueous phase was extracted with DCM:MeOH = 4:1 (60 mL*3), and the organic phase was combined and concentrated to obtain 4.16 g of a crude product. Purification by reverse phase column (ACN / water, 34% acetonitrile) yielded 1.12 g of compound 18c. (Yield: 26.4%)

[1158] MS (ESI): m / z 1325.6 [M+1] + .

[1159] Step 4:

[1160] Compound 18c (1.1 g, 829.85 μmol) was dissolved in DMF (5.5 mL), and thiosalicylic acid (513 mg, 3.33 mmol, 4 eq) and tetrakis triphenylphosphine palladium (292 mg, 252.69 μmol, 0.3 eq) were added. After stirring at room temperature for 3 h, the reaction was quenched by adding water 8 mL, filtered through diatomite, washed with water (15 mL) and EA (15 mL), and the filtrate was diluted with EA (8 mL), separated, and the aqueous phase was extracted with EA:ACN = 6:1 (20 mL*4). The organic layer was discarded, and the water layer was freeze-dried to obtain 1.41 g of a crude compound 18d.

[1161] MS (ESI): m / z 1285.6 [M+1] + .

[1162] Step 5:

[1163] Compound 18d (1.30 g, 1.01 mmol) and compound 7b (547 mg, 724.69 μmol, 1 eq) were dissolved in anhydrous DMF (7 mL), and the system was protected by nitrogen. HATU (441 mg, 1.16 mmol) and DIPEA (326.5 mg, 2.53 mmol) were added in turn under ice water bath. After the addition was completed, the ice water bath was removed, and the reaction was carried out at room temperature for 30 min. The reaction was complete. The reaction solution was added dropwise to EA (70 mL) cooled in an ice water bath, and a solid was precipitated. Filtration yielded 1.08 g of compound 18e (yield: 73.69%).

[1164] MS (ESI): m / z 1011.7 [M / 2 + 1] + .

[1165] Step 6:

[1166] Compound 18e (1.08 g, 534.05 μmol) was dissolved in DMF (20 mL), diethylamine (234.39 mg, 3.20 μmol) was added under ice water bath, the ice water bath was removed after the addition was completed, and the reaction was stirred at room temperature for 2.5 hours. The reaction was complete, TFA (549.08 mg, 4.82 μmol) was slowly added dropwise under ice water bath, and the reaction liquid was added dropwise into the stirring MTBE (200 mL), a solid was precipitated, and 0.94 g of compound 18f was obtained by filtration (yield 97.78%).

[1167] MS (ESI): m / z 1800.3 [M + 1] + .

[1168] Step 7:

[1169] Bromoacetic acid (77.3 mg, 556.32 μmol) was stirred and dissolved in DMF (7 mL), EEDQ (138.2 mg, 558.86 μmol) was added at room temperature, the system was protected by nitrogen, and stirred at room temperature for 1 h. A previously mixed solution of 18f (0.48 g, 250.78 μmol) and DIPEA (32.65 mg, 252.61 μmol) in DMF (2 mL) was added, and the stirring was continued at room temperature for 1 h. The reaction was complete, the reaction liquid was directly sent to HPLC preparation (acetonitrile / water system), the positive component phase was collected, and 142 mg of white solid compound 18 was obtained after freeze-drying (yield: 29.48%).

[1170] MS (ESI): m / z 1921.7 [M + 1] + .

[1171] 1 H NMR (400 MHz, DMSO): δ 9.98 (s, 1H), 8.27-7.89 (m, 4H), 7.83-7.75 (m, 2H), 7.67-7.56 (m, 3H), 7.40-7.30 (m, 3H), 6.52 (s, 1H), 5.45 (s, 2H), 5.37-5.23 (m, 3H), 5.08 (s, 2H), 4.45-3.77 (m, 18H), 3.60-3.37 (m, 24H), 3.22-2.65 (m, 27H), 2.42-1.18 (m, 29H), 0.93-0.76 (m, 9H).

[1172] Preparation of compound 19 of example 36

[1173] Step 1:

[1174] Compound 19a (390 mg, 375.96 μmol, prepared by the known method "WO2016 / 64749"), N-Fluorenylmethoxycarbonyl-glycyl-glycine (159.87 mg, 451.16 μmol, purchased from Genview), HATU (214.43 mg, 563.95 μmol) were dissolved in anhydrous DCM (5 mL), DIPEA (121.48 mg, 939.91 μmol) was added under ice water bath, replaced by nitrogen for three times, stirred at room temperature for 30 minutes, water (4 mL) and MTBE (10 mL) were added to the reaction solution, filtered, collected the filter cake, dried, the filter cake was reslurried with acetonitrile (3 mL) at room temperature once, filtered, dried, to obtain 386 mg of compound 19b (yield 74%).

[1175] MS (ESI): m / z 1373.7 [M+1] + .

[1176] Step 2:

[1177] Compound 19b (386 mg, 281.00 μmol) was dissolved in DCM (2 mL) and DMF (0.8 mL), cooled under ice water bath, diethylamine (164.33 mg, 2.25 mmol) was added, replaced by nitrogen for three times, after adding, stirred at room temperature for 2 hours; the reaction solution was concentrated to dryness, MTBE (3 mL) was added, reslurried at-30℃~-20℃, filtered, repeated twice, the solid was reslurried with MTBE / acetonitrile (1 mL / 1 mL) mixture at-30℃~-20℃ for 30 minutes, filtered, collected the filter cake, dried, to obtain 275 mg of compound 19c (yield 85%).

[1178] MS (ESI): m / z 1151.9 [M+1] + .

[1179] Step 3:

[1180] To a solution of 18b (410 mg, 414.08 pmol) and Fmoc-NH-PEG8-Acid (274 mg, 414.08 pmol, purchased from GenScript) in dichloromethane (6 mL) was added HATU (237 mg, 621.12 pmol) and DIPEA (1.24 mmol, 216 pL) successively. After the addition was completed, the mixture was stirred at room temperature for 1 h. The reaction was monitored by LCMS. After the reaction was completed, the mixture was concentrated to dryness. The residue was diluted with water (20 mL) and EA (20 mL), and the mixture was separated. The aqueous phase was back-extracted with EA (20 mL) for 5 times. The remaining aqueous phase was extracted with DCM / MeOH (10 mL / 3 mL) for 2 times. The organic phases were combined and concentrated to dryness to give compound 19d about 490 mg (yield: 72.34%).

[1181] MS (ESI): m / z 1636.7 [M+1] + .

[1182] Step 4:

[1183] To a solution of 19d (490 mg, 299.53 pmol) in THF (3 mL) and water (1 mL) was added NaOH (72 mg, 1.80 mmol) and piperidine (3.29 mmol, 325 pL) successively. After the addition was completed, the mixture was stirred at room temperature for 6 h. The reaction was monitored by LCMS. After the reaction was completed, the mixture was quenched with TFA (7.79 mmol, 600.00 pL) at 0 °C. Then, 6 mL of ethyl acetate and 2 mL of water were added. The mixture was extracted twice. The aqueous phase was collected and purified by reverse phase purification with 0.1% TFA water / ACN. Compound 19e about 411 mg (yield: 99%) was obtained at ~25% ACN.

[1184] MS (ESI): m / z 1374.6 [M+1] + .

[1185] Step 5:

[1186] To a solution of 19e (411 mg, 299.22 pmol) in dichloromethane (3 mL) was added DIPEA (897.66 pmol, 156 pL) and 19f (180 mg, 448.83 pmol, purchased from Sagny Biotech) successively. After the addition was completed, the mixture was stirred at room temperature for 1 h. The reaction was monitored by LCMS. After the reaction was completed, the mixture was quenched with 1 mL of water. The mixture was concentrated to dryness. The residue was purified by reverse phase purification with pure water / ACN. Compound 19g about 290 mg (yield: 58.35%) was obtained at ~25% ACN.

[1187] MS (ESI): m / z 1661.2 [M+1] + .

[1188] Step 6:

[1189] To 19g (280 mg, 168.58 pmol) and 19c (149 mg, 129.68 pmol) in DMF (2 mL) was added HATU (74 mg, 194.52 pmol) and DIPEA (389.04 pmol, 67.76 pL) respectively. After the addition was complete, the stirring was continued at room temperature for 1 hour. The reaction system was taken to LCMS, the raw material reacted completely, 1 mL of methanol was added to quench the reaction, and the reaction liquid was slowly added to 20 mL of methyl tert-butyl ether. Oil was precipitated, which was collected to obtain 490 mg of crude product. The crude product was purified by reverse phase preparative chromatography (ACN / H20 with 0.1% ammonium bicarbonate) to obtain about 220 mg of compound 19 (yield: 60.71%).

[1190] MS (ESI): m / z 1398.1 [M / 2+1] + .

[1191] 1H NMR (400 MHz, CD3OD): d 7.65-7.59 (m, 4H), 7.45 (s, 3H), 7.37-7.31 (m, 8H), 7.25-7.23 (m, 1H), 7.21-7.20 (m, 1H), 5.14-5.10 (m, 6H), 4.65-4.53 (m, 8H), 4.40-4.34 (m, 11H), 4.24-4.08 (m, 15H), 3.98-3.80 (m, 8H), 3.71-3.67 (m, 8H), 3.49-3.13 (m, 51H), 3.41-3.30 (m, 6H), 3.26-3.12 (m, 8H), 3.09-3.01 (m, 11H), 2.95-2.87 (m, 12H), 2.53-2.31 (m, 12H), 2.18-1.69 (m, 9H), 1.69-1.41 (m, 11H), 1.16-1.10 (m, 6H), 0.97-0.85 (m, 18H).

[1192] Preparation of compound 20 of Example 37

[1193] Step 1:

[1194] Compound 14j (1.0 g, 1.19 mmol), Fmoc-NH-PEG4-Acid (0.71 g, 1.47 mmol) were dissolved in anhydrous DMF (10 mL), the system was protected by nitrogen, HATU (0.60 g, 1.57 mmol) was added, diisopropylethylamine (0.41 g, 3.14 mmol) was added under ice water bath, and the reaction was carried out at room temperature for 1 hour. After the completion of the reaction, the reaction solution was slowly added to MTBE 200 mL, and the slurry was stirred at room temperature for 30 minutes. The solid was collected by filtration to obtain about 1.38 g of compound 20a (yield: 88%).

[1195] MS (ESI): m / z 1310.4 [M+1] + .

[1196] Step 2:

[1197] Compound 20a (1.38 g, 1.05 mmol) was dissolved in DMF (26 mL), and diethylamine (0.46 g, 6.32 mmol) was added at room temperature, and the reaction was carried out for 1.5 hours. Trifluoroacetic acid (1.08 g, 9.48 mmol) was added dropwise to the reaction solution under ice water bath, and the reaction was stirred at room temperature for 10 minutes. The reaction solution was slowly added to MTBE (260 mL), and the solid was precipitated, and the slurry was continued for 30 minutes. The solid was collected by filtration to obtain about 1.0 g of compound 20b (yield: 87%).

[1198] MS (ESI): m / z 1088.5 [M+1] + .

[1199] Step 3:

[1200] Compound 20b (300 mg, 0.28 mmol), trans-4-maleimide methylcyclohexane carboxylic acid hydroxyl succinate (138 mg, 0.41 mmol, purchased from Leyen) were dissolved in DMF (3 mL), and triethylamine (84 mg, 0.83 mmol) was added under ice water bath, and the reaction was carried out at room temperature for 0.5 hours. The reaction solution was slowly added to MTBE (30 mL), and the slurry was stirred for 30 minutes. The solid was collected by filtration, and then purified by reverse phase chromatography column (ACN / H2O, with 0.1% HCOOH) to obtain 107 mg of compound 20 (yield 30%).

[1201] MS (ESI): m / z 1307.5 [M+1] + .

[1202] 1H NMR (400 MHz, DMSO): δ 9.99 (s, 1H), 8.12-8.05 (m, 3H), 7.88-7.72 (m, 4H), 7.62-7.60 (m, 2H), 7.37-7.31 (m, 3H), 7.00 (s, 2H), 6.52 (s, 1H), 6.02-5.94 (m, 1H), 5.45-5.29 (m, 7H), 5.08 (s, 2H), 4.37-4.21 (m, 4H), 3.60-3.59 (m, 2H), 3.47 (s, 7H), 3.23-3.14 (m, 4H), 3.03-2.93 (m, 3H), 2.67 (s, 1H), 2.38-2.33 (m, 4H), 2.27-2.08 (m, 3H), 2.03-1.85 (m, 6H), 1.69-1.59 (m, 5H), 1.54-1.34 (m, 3H), 1.29-1.23 (m, 6H), 0.89-0.82 (m, 9H).

[1203] Example 38 Preparation of ADC-18

[1204] Step:

[1205] The antibody 10 mg Trastuzumab (386.1 μL, 0.067 μmol, 25.9 mg / mL, 1 x PBS 7.2) and PBS 7.2 (113.9 uL) were added to a 2.0 mL EP tube, then TCEP (67.1 μL, 0.67 μmol, 20 mmol / L) was added, and incubated at 37 degrees for 3 hours, removed, ultrafiltration exchanged 4-5 times, and the intermediate was prepared into a 10 mg / mL reaction solution. Compound 20 (1.31 mg, 1.00 μmol) was dissolved in DMSO (50 μL), and the mixture was shaken at 25 degrees for 2 hours. After passing through a desalting column (Zeba™ Thermo), 9.54 mg of ADC-18 (yield 95%) was obtained, and the k value was 7.96 by RP-HPLC method. It was stored at 4 degrees C.

[1206] Example 39

[1207] Step 1:

[1208] Compound 21ab (1.05 g, 9.33 mmol, purchased from Bide) was dissolved in anhydrous DCM (10 mL), and the system was protected by nitrogen. Oxalyl chloride (1.97 g, 15.56 mmol) was added under ice water bath, and the reaction was carried out at room temperature for 2 hours. The reaction was complete after the control of the raw material.

[1209] Under ice water bath, the above methylene chloride solution was added to compound 21aa (2.0 g, 6.22 mmol, purchased from Leyen) in DCM (10 mL), then the reaction was stirred at room temperature for 18 h, the reaction was complete. The reaction solution was washed with 10% sodium carbonate aqueous solution (10 mL x 2), the organic phase was concentrated to dryness, 20 mL EA and 10 mL water were added to dissolve, the layers were separated, the aqueous phase was extracted with 20 mL EA once more, the combined organic phase was dried and filtered, and concentrated to obtain compound 21ac crude product 2.62 g.

[1210] MS (ESI): m / z 416.3 [M+1] + .

[1211] Step 2:

[1212] Compound 21ac (700 mg, 1.68 mmol) was dissolved in DMF (7 mL), 21ad (415 mg, 2.02 mmol, purchased from Leyen), dichlorobis(triphenylphosphine)palladium (118 mg, 0.17 mmol), cuprous iodide (32 mg, 0.17 mmol), triethylamine (511 mg, 5.05 mmol) were added, replaced with argon three times, and the reaction was stirred at 55°C for 3 h. The reaction was complete. The reaction solution was directly concentrated to dryness to obtain a crude product, which was purified by column (MeOH:DCM = 100:0-5:100) to obtain compound 21ae (594 mg, yield 65%).

[1213] MS (ESI): m / z 540.3 [M+1] + .

[1214] Step 3:

[1215] Compound 21ae (7.35 g, 13.62 mmol) was dissolved in acetonitrile (100 mL), 0.1 M potassium dihydrogen phosphate / phosphoric acid aqueous solution (70 mL) was added, and potassium hydrogen sulfate (Oxone) (29.30 g, 47.67 mmol) was added at 10°C. Then the pH of the reaction solution was adjusted to about 3 with 1 M potassium hydrogen phosphate aqueous solution, and the reaction was stirred at 10°C for 14 h. The reaction was filtered, the filter cake was washed with 140 mL EA, the layers were separated, the aqueous phase was extracted with EA (140 mL x 2) once more, the combined organic phase was washed with 40 mL saturated sodium sulfite aqueous solution once, the organic phase was collected, dried with sodium sulfate, filtered, and concentrated to obtain a crude product, which was purified by column (MeOH:DCM = 0:100-5:100) to obtain compound 21af (6.25 g, yield 80%).

[1216] MS (ESI): m / z 572.2 [M+1] + .

[1217] Step 4:

[1218] Compound 21af (6.24 g, 10.92 mmol) was dissolved in DCM (48 mL), TFA (12 mL) was added under ice water bath, after addition, 25 °C was stirred for 3 h, the reaction was complete. The reaction liquid was directly concentrated, 50 mL water was added, extracted with DCM five times (50 mL x 5), the organic phase was collected, dried, filtered and concentrated to obtain compound 21a (5.63 g, yield 100%).

[1219] MS (ESI): m / z 516.2 [M+1] + .

[1220] 1 H NMR (400 MHz, DMSO): δ 9.12 (s, 2H), 7.95-7.92 (m, 1H), 3.62-3.59 (m, 2H), 3.53-3.50 (m, 12H), 3.43-3.40 (m, 5H), 3.24-3.20 (m, 2H), 2.58-2.51 (m, 2H), 2.46-2.43 (m, 2H), 2.30-2.26 (m, 2H), 1.84-1.80 (m, 2H).

[1221] Example 40: Preparation of compound 22

[1222] Step 1:

[1223] Compound 7d (6.75 g, 5.60 mmol) was dissolved in 55 mL of hexafluoroisopropanol, TFA (1.7 mL, 22 mmol) was added at 10 °C. Stirring at room temperature for 8.5 hours. The reaction liquid was slowly added to 500 mL MTBE, and the solid was filtered by beating. The solid was added to 800 mL of acetonitrile and MTBE (V / V = 1:3) mixed solvent for beating, and the solid was collected by filtration to obtain hydrochloride of compound 22a (6.37 g, yield: 99.0%).

[1224] MS (ESI): m / z 1105.7 [M+1] + .

[1225] Step 2:

[1226] The hydrochloride of compound 22a (930 mg, 762.7 μmol) and 14d (727 mg, 915.3 μmol) were added to DMF (8 mL), followed by the addition of TCFH (428 mg, 1.53 mmol) and NMI (626 mg, 7.63 mmol), and after the addition was completed, the reaction was continued at room temperature for 1 hour. The reaction solution was slowly added to 200 mL of MTBE, and the solid was collected by filtration to obtain compound 22b (1.2 g, yield: 83.6%).

[1227] MS (ESI): m / z 1881.7 [M+1] + .

[1228] Step 3:

[1229] Compound 22b (1.3 g, 690.7 μmol) was added to DMF (13 mL), followed by the addition of diethylamine (5.53 mmol, 572 μL), and after the addition was completed, the reaction was continued at room temperature for 1 hour. The reaction solution was slowly added to 200 mL of MTBE, and the solid was collected by filtration to obtain compound 22c (930 mg, yield: 81.1%).

[1230] MS (ESI): m / z 1660.7 [M+1] + .

[1231] Step 4:

[1232] Compound 22c (500 mg, 301.2 μmol) and 21a (201 mg, 391.6 μmol) were added to DMF (4 mL), followed by the addition of HATU (173 mg, 451.8 μmol) and DIPEA (903.7 μmol, 157 μL), respectively, and after the addition was completed, the reaction was stirred at room temperature for 1 hour. The reaction solution was slowly added to 50 mL of MTBE, and the crude product was purified by reverse phase preparation (chromatography column: Welch Xtimate C18, 5 μm; mobile phase: aqueous phase (0.1% formic acid) and acetonitrile, gradient ratio: acetonitrile 35%-50%) to obtain compound 22 (300 mg, yield: 46.1%).

[1233] MS (ESI): m / z 1079.6 [M / 2+1] + .

[1234] 1H NMR (400 MHz, DMSO-d6): δ 9.98 (s, 1H), 9.11 (s, 2H), 8.18-8.01 (m, 4H), 7.94-7.91 (m, 1H), 7.79-7.76 (m, 2H), 7.67 (br, 1H), 7.59 (d, 2H), 7.36 (d, 2H), 7.31 (s, 1H), 6.52 (s, 1H), 5.45 (s, 2H), 5.29-5.26 (m, 4H), 5.08 (s, 2H), 4.39-4.17 (m, 9H), 4.08-3.87 (m, 7H), 3.60-3.38 (m, 50H), 3.22-3.13 (m, 6H), 2.95-2.72 (m, 20H), 2.69-2.54 (m, 5H), 2.49-2.14 (m, 12H), 2.00-1.76 (m, 2H), 0.88-0.81 (m, 10H).

[1235] Example 41: Preparation of compound 23

[1236] Compound 22c (50 mg, 30.12 μmol) and compound 10h (31 mg, 33.14 μmol) were added into DMF (1 mL), followed by the addition of HATU (17 mg, 45.18 μmol) and DIPEA (90.37 μmol, 16 μL), and after the addition was completed, stirring was continued at room temperature for 1 hour. The reaction solution was slowly added dropwise into 50 mL of MTBE, and the crude product was obtained by filtration, which was purified by reverse phase preparation (chromatographic column: Welch Xtimate C18, 5 μm; mobile phase: aqueous phase (0.1% formic acid) and acetonitrile, gradient ratio: acetonitrile 50%-60%) to obtain compound 23 (20 mg, yield: 25.8%).

[1237] MS (ESI): m / z 1284.2 [M / 2+1] + .

[1238] 1H NMR (400 MHz, DMSO-d6): δ 9.98 (s, 1H), 8.19 (d, 1H), 8.05 (d, 1H), 7.88 (d, 1H), 7.78 (d, 1H), 7.66 (d, 1H), 7.59-7.57 (m, 2H), 7.37-7.27 (m, 10H), 6.51 (s, 1H), 5.45 (s, 2H), 5.34-5.24 (m, 4H), 5.07 (s, 2H), 4.39-4.20 (m, 13H), 4.27-3.86 (m, 11H), 3.71-3.42 (m, 41H), 3.33-3.23 (m, 4H), 3.01-2.67 (m, 20H), 2.40-2.33 (m, 4H), 2.19-1.66 (m, 15H), 1.55-1.39 (m, 6H), 1.30-1.24 (m, 3H), 0.89-0.82 (m, 10H).

[1239] Example 42: Preparation of compound 24

[1240] Step 1:

[1241] A mixture of compound 24a (3.90 g, 8.08 mmol, purchased from Genway) and TFA salt of compound 7b (5.01 g, 5.77 mmol) was dissolved in 40 mL of DMF, HATU (3.30 g, 8.68 mmol), DIPEA (2.30 g, 17.77 mmol) was added, stirred at room temperature for 1 hour. The reaction solution was slowly added to 800 mL of MTBE, stirred for 1 hour, and the solid was collected by filtration. 50 mL of acetonitrile was added to the solid, stirred for 30 minutes, then 500 mL of MTBE was added, the solid was collected by filtration to obtain compound 24b (6.97 g, yield: 99.1%).

[1242] MS (ESI): m / z 1219.5 [M+1] + .

[1243] Step 2:

[1244] Compound 24b (3.47 g, 2.85 mmol) was dissolved in 28 mL of hexafluoroisopropanol, TFA (660 μL, 8.57 mmol) was added at 5-10°C. Stirring at room temperature for 5 hours. The reaction solution was slowly added to 200 mL of MTBE, the solid was collected by filtration, and the solid was reslurried in a mixture of 180 mL of acetonitrile and MTBE (V / V = 1:5) to collect the solid to obtain compound 24c (3.25 g, yield: 92.6%).

[1245] MS (ESI): m / z 1119.7 [M+1] + .

[1246] Step 3:

[1247] A mixture of compound 24c (477 mg, 387 μmol) and compound 14d (377 mg, 474 μmol) was dissolved in 5 mL of DMF, HATU (223 mg, 586 μmol), DIPEA (221 mg, 1.71 mmol) was added, stirred at room temperature for 40 minutes. The reaction solution was purified by reverse phase silica gel column chromatography with eluent system (column: C18, mobile phase: aqueous phase and methanol, gradient ratio: methanol 0%-70%, 70% product), to obtain compound 24d (400 mg, yield: 54.5%).

[1248] MS (ESI): m / z 1896.3 [M+1] + .

[1249] Step 4:

[1250] Compound 24d (400 mg, 211 μmol) was dissolved in DMF (4 mL), diethylamine (170 μL, 1.64 mmol) was added, stirred at room temperature for 1.5 hours. The reaction solution was slowly added to 40 mL of MTBE, stirred for 1 hour, and the solid was collected by filtration. 4 mL of acetonitrile was added to the solid, stirred for 30 minutes, then 40 mL of MTBE was added, and the solid was collected by filtration to obtain compound 24e (250 mg, yield: 70.8%).

[1251] MS (ESI): m / z 1673.8 [M+1] + .

[1252] Step 5:

[1253] Compound 24e (200 mg, 119 μmol), compound 21a (84 mg, 163 μmol) was dissolved in DMF (2.5 mL), HATU (69 mg, 181 μmol), DIPEA (83 μL, 476 μmol) was added. Stirred at room temperature for 0.5 hours. The reaction solution was purified by high performance liquid chromatography (column: Welch Xtimate C18, 5 μm; mobile phase: aqueous phase (0.1% formic acid) and acetonitrile, gradient ratio: acetonitrile 35%-50%) to obtain compound 24 (146 mg, yield: 56.3%).

[1254] MS (ESI): m / z 1086.2 [M / 2+1] + .

[1255] 1 H-NMR (400 MHz, DMSO-d6): δ 9.97 (s, 1H), 9.11 (s, 2H), 8.15 (d, 1H), 8.02 (dd, 2H), 7.91 (t, 1H), 7.77 (d, 1H), 7.76-7.60 (m, 1H), 7.67 (d, 2H), 7.36 (d, 2H), 7.31 (s, 1H), 6.51 (s, 1H), 5.45 (s, 2H), 5.34-5.23 (m, 3H), 5.08 (s, 2H), 4.39-3.87 (m, 15H), 3.61-3.55 (m, 4H), 3.49-3.47 (m, 33H), 3.43-3.38 (m, 7H), 3.27-3.07 (m, 9H), 2.94-2.67 (m, 21H), 2.60-2.52 (m, 3H), 2.44-2.33 (m, 7H), 2.26 (t, 2H), 2.24-2.14 (m, 2H), 2.00-1.76 (m, 5H), 1.65-1.43 (m, 4H), 1.30-1.23 (m, 5H), 0.89-0.82 (m, 9H).

[1256] Example 43: Preparation of compound 25

[1257] Step 1:

[1258] Compound O-(2-aminoethyl)-O'-[2-(tert-butoxycarbonyl-amino)ethyl]tetraethyleneglycol (700 mg, 1.84 mmol, purchased from Genway) was dissolved in DCM (30 mL), N-Fluorenylmethoxycarbonyl-L-glutamic acid 1-allyl ester (753 mg, 1.84 mmol, purchased from Genway) was added, the system was protected by nitrogen, and an ice water bath was used for cooling. HATU (699 mg, 1.84 mmol) and DIPEA (237 mg, 1.84 mmol) were added, and the reaction was completed at room temperature. Water (20 mL) was added for quenching, and the organic phase was collected after separation. The organic phase was dried with anhydrous sodium sulfate, concentrated, and the residue was prepared with a C18 reverse phase column (water: acetonitrile = 0-100%). The prepared liquid was concentrated to obtain compound 25a (1.1 g, yield: 77.4%).

[1259] MS (ESI): m / z 772.6 [M+1] + .

[1260] Step 2:

[1261] Compound 25a (1.0 g, 1.3 mmol) was dissolved in DCM (30 mL), TFA (6 mL) was added, the reaction was complete at room temperature, concentrated, DCM (30 mL x 2) was taken twice, and the oil pump was dried. The title product 25b (0.95 g) was obtained, and the product was directly used in the next reaction without purification.

[1262] MS (ESI): m / z 672.4 [M + 1] + .

[1263] Step 3:

[1264] Compound 25b (0.8 g, 1.13 mmol) was dissolved in DCM (15 mL), Ac-Sar(6)-OH (550 mg, 1.13 mmol, purchased from Haoyuan) was added, HATU (515 mg, 1.36 mmol) and DIPE...

Claims

1. A compound of formula IA ###0001### or a pharmaceutically acceptable salt thereof, wherein, D is a drug unit; Sp is Lp-(X) b ; X is a spacer unit; Lp is an amino acid unit; U is a hydrophilic unit comprising polyethylene glycol structural units and poly-sarcosine structural units; L is a stretch unit; R is a linker group; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and b is selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

2. The compound or pharmaceutically acceptable salt thereof according to claim 1, wherein the compound of Formula IA or pharmaceutically acceptable salt thereof is a compound of Formula la or pharmaceutically acceptable salt thereof, wherein, D is a drug unit; X is a spacer unit; Lp is an amino acid unit; U is a hydrophilic unit comprising polyethylene glycol structural units and poly-sarcosine structural units; L is a stretch unit; R is a linker group; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and b is selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10.

3. The compound according to claim 1 or 2, or a pharmaceutically acceptable salt thereof, wherein the spacer unit comprises wherein R e is selected from halogen, C 1-6 alkyl, C 1-6 alkoxy or v is selected from an integer from 0-4; B1is a bond to the Lp terminus; B2is a bond to the -D terminus.

4. The compound according to claim 3, or a pharmaceutically acceptable salt thereof, wherein the spacer unit comprises wherein R e is selected from halo, C 1-6 alkyl, C 1-6 alkoxy or v is selected from an integer from 0-4; B1is a bond to the Lp terminus; B2is a bond to the -D terminus.

5. The compound or pharmaceutically acceptable salt thereof according to any one of claims 1-3, wherein the spacer unit comprises p-aminobenzyloxy carbonyl.

6. The compound or pharmaceutically acceptable salt thereof according to claim 1, wherein the spacer unit comprises the following moiety: -(CR 1 R 2 ) m1 -O(CR 1 R 2 ) m2 -CR 3 R 4 -C(O)-、-(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -CR 3 R 4 -C(O)-、-(CR 1 R 2 ) m1 O-CR 3 R 4 (CR 1 R 2 ) m2 -、-(CR 1 R 2 ) m1 OCR 3 R 4 -C(O)-、-(CR 1 R 2 ) m1 -O-(CR 1 R 2 ) m2 C(O)-、-(CR 1 R 2 ) m1 -S-(CR 1 R 2 ) m2 -CR 3 R 4 -C(O)-、-(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -O-CR 3 R 4 -C(O)-、-(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -O-M-C(O)- and -(CR 1 R 2 ) m1 NH-(CR 1 R 2 ) m2 -CR 3 R 4 -, wherein R 1 and R 2 are the same or different and each is independently selected from hydrogen, deuterium atom, halogen or alkyl; R 3 is selected from hydrogen, C 3-6 cycloalkylalkyl, C 3-6 cycloalkyl or 3-6 membered heterocycloalkyl; R 4 is selected from hydrogen, haloalkyl, C 3-6 cycloalkyl or 3-6 membered heterocycloalkyl, preferably hydrogen; or, R 3 and R 4 together with the carbon atom to which they are attached form a C 3-6 cycloalkyl or 3-6 membered heterocycloalkyl; m1 and m2 are each independently selected from 0, 1, 2 or 3; M is selected from C 3-6 cycloalkyl or 3-6 membered heterocycloalkyl.

7. The compound according to claim 6, or a pharmaceutically acceptable salt thereof, wherein the spacer unit X comprises the following moiety: -(CH2)3-C(O)-, -CH2-O-CH2-C(O)-, -(CH2)2-O-CH2-C(O)-, -NHCH2-, -NH-(CH2)3-C(O)-, -NH-CH2-O-CH2-C(O)-, -NH-(CH2)2-O-CH2-C(O)-, ​ 8. The compound according to any one of claims 1-7, or a pharmaceutically acceptable salt thereof, wherein the hydrophilic unit is -R b -[R e -(OCH2CH2) q -R c -R f -[C(O)CH2NCH3] o -R a ] v , -R b -[R e -(OCH2CH2) q -R c -R f -(OCH2CH2) q -R a ] v or -R b -[R e -[C(O)CH2NCH3] o -R c -R f -(OCH2CH2) q -R a ] v , v is selected from 1 or 2; wherein, 1) R b is selected from the group consisting of a bond or -AA-, -AA- is selected from the group consisting of 1 to 5 amino acid residues selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; R e selected from a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-; R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 peptide residues of amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; R f selected from a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -, 1-12 alkylene-C(O)-NR d -, 1-12 alkylene-NR d -, 1-12 alkylene-, -NR d -, 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-; R d selected from hydrogen or C 1-6 alkyl; R a selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl; o is an integer from 1 to 20, and q is an integer from 1 to 20; or 2) R b selected from orthogonal linkers * is the connecting end with Lp, A7 and A8 are respectively the connecting end with R e connecting bond; R e selected from a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -, 1-12 alkylene-C(O)-NR d -, 1-12 alkylene-NR d -, 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-; R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 peptide residues of amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; R f selected from a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-; R d selected from hydrogen or C 1-6 alkyl; R a selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl; o is an integer from 1 to 20, and q is an integer from 1 to 20.

9. The compound or pharmaceutically acceptable salt thereof according to claim 1 or 8, wherein the hydrophilic unit is wherein, 1) R b selected from the group consisting of a bond or -AA-, R c selected from the group consisting of a bond or -BB-, -AA- is selected from the group consisting of 1 to 5 peptide residues selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, -BB- is selected from the group consisting of 1 to 5 peptide residues selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; R d selected from hydrogen or C 1-6 alkyl; R a selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl; v is selected from 1 or 2; o is selected from an integer from 1 to 20, q is selected from an integer from 1 to 20, and n is selected from an integer from 0 to 12; or 2) R b selected from orthogonal linkers "*" is the bond to Lp, and A7 and A8 are the bonds to -C(O)-; R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 peptide residues of amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; R d selected from hydrogen or C 1-6 alkyl; R a selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl; v is selected from 1 or 2; o is an integer from 1 to 20, q is an integer from 1 to 20, and n is an integer from 0 to 12.

10. The compound or pharmaceutically acceptable salt thereof according to any one of claims 1-9, wherein the hydrophilic unit is Where o is an integer from 1 to 20, q is an integer from 1 to 20, and R a Selected from C 1- 6-alkyl, C 1-6 Alkoxy and C 3-6 Cycloalkyl.

11. The compound or pharmaceutically acceptable salt thereof according to any one of claims 1-9, wherein the hydrophilic unit is wherein o is an integer from 1 to 20, q is an integer from 1 to 20, R a selected from C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl.

12. The compound or pharmaceutically acceptable salt thereof according to any one of claims 1-11, wherein the amino acid unit comprises a peptide residue consisting of 2 to 7 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, and aspartic acid.

13. The compound or pharmaceutically acceptable salt according to any one of claims 1-12, wherein the amino acid unit further comprises -(CH2CH20)n1- or -(CH2CH20)n2-. n1 - C(O)CH2NCH3 1-2 - C(O)CH2NCH3 n2 - wherein n1, n2 are integers from 1 to 10.

14. The compound according to any one of claims 1-11, or a pharmaceutically acceptable salt thereof, wherein the amino acid unit comprises the following moiety: wherein, W is -NH-heterocycloalkyl- or heterocycloalkyl; Y is heteroaryl, aryl, -C(O)C 1-6 alkylene, C 2-6 alkenylene, C 1-6 alkylene or -C 1-6 alkylene-NH-; each R 5 is independently selected from C 1-10 alkyl, C 2-10 alkenyl, C 1-6 alkylene-NH2, -(C 1-10 alkylene)NHC(NH)NH2 or -(C 1- 10 alkylene)NHC(O)NH2; R 6 and R 7 are each independently H, C 1-10 alkyl, C 2-10 alkenyl, arylalkyl, heteroarylalkyl, or R 6 and R 7 together can form a C 3-7 cycloalkyl or 3-7 membered heterocycloalkyl.

15. The compound according to claim 14, or a pharmaceutically acceptable salt thereof, wherein Y is selected from 16. The compound or pharmaceutically acceptable salt thereof according to any one of claims 1-15, wherein the amino acid unit comprises a lysine residue.

17. The compound or pharmaceutically acceptable salt thereof according to any one of claims 1-16, wherein the hydrophilic unit is attached to a lysine residue in the amino acid unit.

18. The compound according to any one of claims 2-17, or a pharmaceutically acceptable salt thereof, wherein B is B is L 2 and L 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, and A3is a bond to the U terminus.

19. The compound according to any one of claims 2-18, or a pharmaceutically acceptable salt thereof, wherein is wherein B is L 2 comprising a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, preferably valine-arginine (Val-Arg), valine-alanine (Val-Ala), valine-citrulline (Val-Cit), glycine-glycine-phenylalanine-glycine (Gly-Gly-Phe-Gly), glycine-glycine-valine-alanine (Gly-Gly-Val-Ala), glycine-glycine-valine-citrulline (Gly-Gly-Val-Cit), alanine-alanine (Ala-Ala), valine-lysine (Val-Lys); A1 is the bond to L, A2 and A7 are the bonds to D, and A3 is the bond to U.

20. The compound or pharmaceutically acceptable salt thereof according to any one of claims 2-18, wherein B is B is L 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, and A3is a bond to the U terminus.

21. The compound according to any one of claims 2-18, or a pharmaceutically acceptable salt thereof, wherein A1is a bond to the L terminus, A2, A7is a bond to the D terminus, and A3is a bond to the U terminus. A1is a bond to the L terminus, A2, A7is a bond to the D terminus, and A3is a bond to the U terminus. A1is a bond to the L terminus, A2, A7is a bond to the D terminus, and A3is a bond to the U terminus.

22. The compound according to claim 18, or a pharmaceutically acceptable salt thereof, wherein L 2 or L 3 also comprises -(CH2CH2O) n1 -C 1- 2alkylene-C(O)- or -[C(O)CH2NCH3] n2 - wherein n1, n2 are integers from 1 to 10.

23. The compound according to any one of claims 1-22, or a pharmaceutically acceptable salt thereof, wherein R is selected from the group consisting of optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted and optionally substituted wherein each E is independently selected from a leaving group, such as halogen; r is selected from an integer from 1-6, such as 3 and 4; is a chemical bond or is absent.

24. The compound according to any one of claims 1-23, or a pharmaceutically acceptable salt thereof, wherein L comprises -R 8 -L 1 - wherein R 8 is selected from -W1-C(O)-, -C(O)-W1-C(O)-, -W1-(CH2CH2O) p C(O)-, -W1-(CH2CH2O) p CH2C(O)-, -W1-(CH2CH2O) p CH2CH2C(O)-, -(CH2CH2O) p C(O)-, -(CH2CH2O) p CH2C(O)-, -(CH2CH2O) p CH2CH2C(O)-, wherein W1 is selected from C 1-8 alkylene, C6 aryl, C 5-6 heteroaryl, C 1-8 alkylene-cycloalkyl, or straight chain heteroalkyl of 1 to 8 atoms, said heteroalkylene comprising 1 to 3 heteroatoms selected from N, O, or S, wherein said C 1-8 alkylene, C6 aryl, C 5-6 heteroaryl, C 1-8 alkylene-cycloalkyl, and straight chain heteroalkylene are each independently optionally further substituted with one or more substituents selected from halogen, hydroxyl, cyano, nitro, amino, C 1-6 alkyl, or C 1-6 alkoxy; L 1 -NR 9 (CH2CH2O) p CH2CH2C(O)-, -NR 9 (CH2CH2O) p CH2C(O)-, -S(CH2) p C(O)-, -(CH2) p C(O)- or a bond, preferably a bond; wherein each p is independently selected from an integer from 1 to 20, R 9 each independently selected from a hydrogen atom and a C 1-8 alkyl group, said C 1- 8alkyl group is optionally substituted with one or more substituents selected from halogen, hydroxy, cyano, nitro, amino, C 1-6 alkoxy groups.

25. The compound according to claim 24, or a pharmaceutically acceptable salt thereof, wherein R 8 is selected from -C 1-6 alkylene-C(O)-, -(CH2-CH20)2C(O)-, -(CH2-CH20)2CH2C(O)-, -(CH2-CH20)2CH2CH2C(O)-, -(CH2-CH20)3C(O)-, and -(CH2-CH20)4C(O)-, or R 8 is selected from -C 1-8 alkylene-cyclohexyl-C(O)-, -(CH2-CH20)4CH2C(O)-, and -(CH2-CH20)6CH2C(O)-.

26. The compound or pharmaceutically acceptable salt thereof according to claim 1, wherein the hydrophilic unit is attached to a glutamic acid in the amino acid unit.

27. The compound or pharmaceutically acceptable salt thereof according to any one of claims 1-26, wherein a = 1.

28. The compound or pharmaceutically acceptable salt thereof of claim 18 or 19, wherein L 2 Also included t is 0, 1, 2, or 3, A4is a bond to the B terminus, A5and A6are bonds to the -X-D terminus.

29. The compound according to claim 1 or 2, or a pharmaceutically acceptable salt thereof, wherein Drug Unit D is selected from the group consisting of a cytotoxic compound or a glucocorticoid, preferably eribulin or an analog thereof, trabectedin or an analog thereof, austinin E or an analog thereof, austinin F or an analog thereof, camptothecin or an analog thereof, cabazitaxel or an analog thereof, more preferably 30. The compound or pharmaceutically acceptable salt thereof according to claim 1, wherein the hydrophilic unit U is attached to the spacer unit X.

31. The compound or pharmaceutically acceptable salt thereof according to claim 1 or 30, wherein the compound of Formula IA or a pharmaceutically acceptable salt thereof is a compound of Formula IB or a pharmaceutically acceptable salt thereof, wherein D is a drug unit; X is a spacer unit; Lp is an amino acid unit; U is a hydrophilic unit comprising polyethylene glycol structural units and polysarcosine structural units; L is a linker unit; R is a linking group; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.

32. The compound or pharmaceutically acceptable salt thereof according to any one of claims 1, 30, or 31, wherein is G is selected from a bond, -O-, -C(O)-, -(CR 10 R 11 ) g N(R cc )-, -S-, -S(O)-, -S(O)2-, -S(O)2-C 1-6 alkylene-, -S(O)2-C 2-6 alkenylene-, a triazolyl-containing group, or a combination thereof; R 10 and R 11 are the same or different and each is independently selected from hydrogen, a deuterium atom, a halogen, or an alkyl group; R aa selected from hydrogen or C 1-6 alkyl; R bb selected from halogen or C 1-6 alkyl; R cc selected from hydrogen or C 1-6 alkyl; A1is a bond to the end of Lp, and A2is a bond to the end of D; v is selected from 0, 1, 2, 3, or 4; g is selected from 0, 1, 2, or 3; U is as defined in any one of claims 1, 8-11, 16-17.

33. The compound or pharmaceutically acceptable salt thereof of any one of claims 30-32, wherein is selected from wherein R aa , R bb , Al, A2, v and G are as defined in claim 32; U is as defined in any one of claims 1, 8-11, 16-17.

34. The compound or pharmaceutically acceptable salt thereof of any one of claims 30-33, wherein is selected from wherein A1, A2are as defined in claim 32; U is as defined in any one of claims 1, 8-11, 16-17.

35. The compound or pharmaceutically acceptable salt thereof according to claim 1, wherein the compound of Formula IA is selected from: wherein p1, p2, p3, p4are each independently selected from 0, 1, 2, 3, and 4; r is selected from an integer from 1 to 6; E is a leaving group, such as a halogen; X, D, and U are as defined in claim 1.

36. The compound or pharmaceutically acceptable salt thereof according to any one of claims 1-35, wherein the compound of Formula IA is selected from: wherein p1, p2, p3are each independently selected from 0, 1, 2, 3, and 4; r is selected from an integer from 1 to 6; D is as defined in claim 1; R3, R4are as defined in claim 6.

37. The compound or pharmaceutically acceptable salt thereof according to any one of claims 1-35, represented by the following formula: wherein p1, p2, p3, p4are each independently selected from 0, 1, 2, 3, and 4; r is selected from an integer from 1 to 6; E is a leaving group, such as a halogen; U and D are as defined in claim 1.

38. The compound of any one of claims 35-37, or a pharmaceutically acceptable salt thereof, wherein U is wherein o is an integer from 1 to 20, q is an integer from 1 to 20, R a selected from C 1-6 alkyl, C 1-6 alkoxy, and C 3-6 cycloalkyl.

39. A Ligand-Drug Conjugate of Formula II A or a pharmaceutically acceptable salt thereof, wherein, Ab is a polypeptide or antibody; k is selected from 1-10, can be an integer or a decimal; z is selected from units covalently linked to Ab; a is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9, 10; L is a stretch unit; Sp is Lp-(X) b ; Lp is an amino acid unit; X is a spacer unit; b is selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10; D is a drug unit; U is a hydrophilic unit comprising polyethylene glycol structural units and polysarcosine structural units.

40. The Ligand-Drug Conjugate or a pharmaceutically acceptable salt thereof according to claim 39, wherein the Ligand-Drug Conjugate of Formula II A or a pharmaceutically acceptable salt thereof is a Ligand-Drug Conjugate of Formula IIa or a pharmaceutically acceptable salt thereof, wherein Ab is a polypeptide or an antibody; k is selected from 1-10, which can be an integer or a decimal number; z is selected from a unit covalently linked to Ab; Lp is an amino acid unit; X is a spacer unit; D is a drug unit; L is a linker unit; U is a hydrophilic unit comprising polyethylene glycol structural units and polysarcosine structural units.

41. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to claim 39 or 40, wherein the hydrophilic unit is -R b -[R e -(OCH2CH2) q -R c -R f -[C(O)CH2NCH3] o -R a ] v , -R b -[R e -(OCH2CH2) q -R c -R f -(OCH2CH2) q -R a ] v or -R b -[R e -[C(O)CH2NCH3] o -R c -R f -(OCH2CH2) q -R a ] v , v is selected from 1 or 2, o is an integer from 1 to 20, and q is an integer from 1 to 20. wherein 1) R b is selected from the group consisting of a bond or -AA-, -AA- is selected from the group consisting of 1 to 5 amino acid residues selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; R e selected from a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -, 1-12 alkylene-C(O)-NR d -, 1-12 alkylene-NR d -, 1-12 alkylene-, -NR d -, 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-; R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 peptide residues of amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; R f selected from a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-; R d selected from hydrogen or C 1-6 alkyl; R a selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl; or 2) R b selected from orthogonal linkers * is the connecting end with Lp, A7 and A8 are respectively the connecting end with R e e e e e e e <000038 R e selected from a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, -C(O)-C 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -C(O)-, -C 1-12 alkylene-C(O)-NR d -C(O)-, -C 1-12 alkylene-NR d -C(O)-C 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-; R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 peptide residues of amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; R f selected from a bond, C 1-12 alkylene, -C(O)-, -NR d -C 1-12 alkylene-, -C 1-12 alkylene-NR d -, 1-12 alkylene-, -C 1-12 alkylene-C(O)-, -C 1-12 alkylene-NR d -, 1-12 alkylene-C(O)-NR d -, 1-12 alkylene-NR d -, 1-12 alkylene-, -NR d -C 1-12 alkylene-C(O)-, -C(O)-C 1-12 alkylene-NR d - or -NR d -C(O)-; R d selected from hydrogen or C 1-6 alkyl; R a selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl.

42. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-41, wherein the hydrophilic unit is wherein, 1) R b selected from the group consisting of a bond or -AA-, R c selected from the group consisting of a bond or -BB-, -AA- is selected from the group consisting of 1 to 5 peptide residues selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, -BB- is selected from the group consisting of 1 to 5 peptide residues selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; R d selected from hydrogen or C 1-6 alkyl; R a selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl; v is selected from 1 or 2; o is selected from an integer from 1 to 20, q is selected from an integer from 1 to 20, n is selected from an integer from 0 to 12; or 2) R b selected from orthogonal linkers "*" is a bond to the end of Lp, and A7and A8are a bond to -C(O)-, respectively; R c is selected from the group consisting of a bond or -BB-, -BB- is selected from the group consisting of 1 to 5 peptide residues of amino acids selected from the group consisting of phenylalanine, glycine, alanine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; R d selected from hydrogen or C 1-6 alkyl; R a selected from hydrogen, C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl; v is selected from 1 or 2; o is an integer from 1 to 20, q is an integer from 1 to 20, n is an integer from 0 to 12; Further, the hydrophilic units are preferably wherein o is an integer from 1 to 20, q is an integer from 1 to 20, R a selected from C 1-6 alkyl, C 1-6 alkoxy and C 3-6 cycloalkyl.

43. The Ligand-Drug Conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-42, wherein the amino acid unit comprises a peptide residue consisting of 2 to 7 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid.

44. The Ligand-Drug Conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-43, wherein the amino acid unit comprises a lysine residue.

45. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-44, wherein the amino acid unit further comprises -(CH2CH20)n1- or -(CH2CH20)n2-. n1 - C(O)-, -C(O)N(R')- 1-2 - alkylene-C(O)-, or -[C(O)CH2NCH3] n2 - wherein n1, n2 are integers from 1 to 10.

46. The compound or pharmaceutically acceptable salt thereof of any one of claims 40-45, wherein B is B is L 2 and L 3 each comprises a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid; A1is a bond to the L terminus, A2, A7are bonds to the D terminus, and A3is a bond to the U terminus.

47. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 40-46, wherein is wherein B is L 2 comprising a peptide residue consisting of 1 to 5 amino acids selected from phenylalanine, alanine, glycine, valine, lysine, citrulline, serine, glutamic acid, aspartic acid, preferably valine-arginine (Val-Arg), valine-alanine (Val-Ala), valine-citrulline (Val-Cit), glycine-glycine-phenylalanine-glycine (Gly-Gly-Phe-Gly), glycine-glycine-valine-alanine (Gly-Gly-Val-Ala), glycine-glycine-valine-citrulline (Gly-Gly-Val-Cit), alanine-alanine (Ala-Ala), valine-lysine (Val-Lys); A1is a bond to the L terminus, A2, A7are bonds to the D terminus, and A3is a bond to the U terminus.

48. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-47, wherein Z is selected from the group consisting of optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted optionally substituted and optionally substituted wherein r is selected from an integer from 1-6, such as 3 and 4; "*" indicates the attachment point to Ab.

49. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-48, wherein the antibody is selected from the group consisting of murine, chimeric, humanized, and fully human antibodies.

50. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-49, wherein the antibody is selected from the group consisting of anti-HER2 (ErbB2) antibodies, anti-EGFR antibodies, anti-B7-H3 antibodies, anti-c-Met antibodies, anti-HER3 (ErbB3) antibodies, anti-HER4 (ErbB4) antibodies, anti-CD20 antibodies, anti-CD22 antibodies, anti-CD30 antibodies, anti-CD33 antibodies, anti-CD44 antibodies, anti-CD56 antibodies, anti-CD70 antibodies, anti-CD73 antibodies, anti-CD105 antibodies, anti-CEA antibodies, anti-A33 antibodies, anti-Cripto antibodies, anti-EphA2 antibodies, anti-G250 antibodies, anti-MUC1 antibodies, anti-Lewis Y antibodies, anti-VEGFR antibodies, anti-GPNMB antibodies, anti-Integrin antibodies, anti-PSMA antibodies, anti-Tenascin-C antibodies, anti-SLC44A4 antibodies, anti-CD79 antibodies, anti-TROP-2 antibodies, anti-CD79B antibodies, anti-Mesothelin antibodies, anti-TF antibodies, and anti-Claudin 18.2 antibodies.

51. The ligand-drug conjugate according to any one of claims 39-50, wherein the antibody is selected from the group consisting of trastuzumab, pertuzumab, nimotuzumab, emibetuzumab, inotuzumab, ocaratuzumab, venetoclax-piqnatumab, vibostuzumab, gemtuzumab, bivatuzumab, morfoluzumab, cBR96, trastuzumab deruxtecan, and glematumamab.

52. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to claim 39, which is selected from the following structural formula: wherein each of p1, p2, p3, and p4 is independently selected from 0, 1, 2, 3, and 4; k is selected from 1-10, which can be an integer or a decimal number; r is selected from an integer of 1-6; Ab is a polypeptide or an antibody; U, X, and D are as defined in claim 39.

53. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to claim 39 or 52, which is selected from the following structural formula: wherein each of pi, p2, p3, p4 is independently selected from 0, 1, 2, 3, and 4; k is selected from 1-10, which can be an integer or a decimal number; Ab is a polypeptide or an antibody; R 3 and R 4 R 3 , R 4 as defined in claim 6; U and D are as defined in claim 39.

54. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to claim 39 or 52, which is selected from the following structural formula: wherein each of p1, p2, p3, and p4 is independently selected from 0, 1, 2, 3, and 4; k is selected from 1-10, which can be an integer or a decimal number; Ab is a polypeptide or an antibody; r is selected from an integer of 1-6; U and D are as defined in claim 39.

55. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-54, wherein -D is selected from 56. The ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-55, wherein Ab is selected from trastuzumab or pertuzumab or trastuzumab deruxtecan.

57. A pharmaceutical composition comprising the ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-56, and a pharmaceutically acceptable pharmaceutical excipient.

58. Use of the ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-56, or the pharmaceutical composition of claim 57, in the manufacture of a medicament for treating or preventing a tumor, preferably a cancer associated with HER2, HER3, B7H3, EGFR, TF or Claudin 18.2 expression.

59. Use of the ligand-drug conjugate or a pharmaceutically acceptable salt thereof according to any one of claims 39-56, or the pharmaceutical composition of claim 57, in the manufacture of a medicament for treating and / or preventing a cancer, wherein the cancer is preferably breast cancer, ovarian cancer, cervical cancer, uterine cancer, prostate cancer, kidney cancer, liver cancer, stomach cancer, thyroid cancer, pancreatic cancer and lymphoma.

Images