Linker-drug and antibody-drug conjugate (ADC) employing the same

1. A linker-drug represented by formula (IA) or formula (IA′):

wherein C is a conjugating linker; L is a linker unit; Do, Dp and Dq are drug units; and m is an integer of 1; o is an integer ranging from 1 to 4; p is an integer ranging from 1 to 4; and q is an integer ranging from 1 to 4;

wherein the structure of the conjugating linker is represented by formula (IIa), formula (IIb), or formula (IIc):

wherein X is a leaving group,

wherein the wave line of formula (IIa), formula (IIb), or formula (IIc) indicates the covalent attachment site to L.

2. The linker-drug as claimed in claim 1 , wherein the linker unit is a cleavable linker or a noncleavable linker.

3. The linker-drug as claimed in claim 2 , wherein the cleavable linker comprises a peptide unit (-AAs-) selected from a group consisting of -valline-citruline-(-Val-Cit-), -valline-lysine-(-Val-Lys-), -valline-arginine-(-Val-Arg-), -phenylalanine-citruline-(-Phe-Cit-), -phenylalanine -lysine-(-Phe-Lys-), and -phenylalanine-arginine-(-Phe-Arg-).

4. The linker-drug as claimed in claim 1 ,

wherein L is linear alkyl, cycloalkyl, heterocycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, poly(ethylene glycol) chain, or a combination thereof; and Do, Dp and Dq are independently cytotoxic drugs, anti-autoimmune disease drugs, or anti-inflammation drugs.

5. The linker-drug as claimed in claim 1 , wherein the drug unit is amanitins, anthracyclines, auristatins, baccatins, calicheamicins, camptothecins, cemadotins, colchicines, colcimids, combretastatins, cryptophycins, discodermolides, docetaxel, doxorubicin, duocarmycins, echinomycins, eleutherobins, epothilones, estramustines, lexitropsins, maytansines, maytansinoids, methotrexate, netropsins, pyrrolo[2,1-c][1,4]benzodi-azepines (PBDs), puromycins, rhizoxins, SN-38, taxanes, tubulysins, or vinca alkaloids.

6. The linker-drug as claimed in claim 1 , wherein the leaving group is —Cl, —Br, —I, —F, —OTs, —OMs, —OTf or —OBs.

7. An antibody-drug conjugate (ADC) represented by formula (IVA) or formula (IVA′):

wherein A is a full-length antibody, or an antibody fragment; C′-(L-Do)m and

are linker-drugs, wherein C′ is a conjugating linker; L is a linker unit; Do, Dp and Dq are drug units; and m is an integer of 1; o is an integer ranging from 1 to 4; p is an integer ranging from 1 to 4; and q is an integer ranging from 1 to 4;

wherein A is conjugated to the linker-drug through two thiol groups respectively present in two cysteine residues of A;

A-C′ is the following structure represented by formula (Va), formula (Vb), or formula (Vc):

wherein the wave line of formula (Va), formula (Vb), or formula (Vc) indicates the covalent attachment site to L; A′ indicates the remaining part of A which conjugated to the linker-drug through two thiol groups respectively present in two cysteine residues of A.

8. The antibody-drug conjugate (ADC) as claimed in claim 7 , wherein A targets cell surface receptors or tumor-related antigens.

9. The antibody-drug conjugate (ADC) as claimed in claim 7 , wherein the antibody is a chimeric antibody or a functionally active fragment thereof, a humanized antibody or a functionally active fragment thereof, a human antibody or a functionally active fragment thereof, a mouse antibody or a functionally active fragment thereof, a rat antibody or a functionally active fragment thereof, a goat antibody or a functionally active fragment thereof, or a rabbit antibody or a functionally active fragment thereof.

10. The antibody-drug conjugate (ADC) as claimed in claim 7 , wherein the antibody is an IgG1 antibody or a functionally active fragment thereof, an IgG4 antibody or a functionally active fragment thereof.

11. The antibody-drug conjugate (ADC) as claimed in claim 7 , wherein the antibody is HLX-07, EG12014, anti-EpCAM Ab and IgG1, Rituximab, Ibritumomab tiuxetan, Tositumomab, Brentuximab, Alemtuzumab, IGN101, Adecatumumab, Labetuzumab, huA33, Pemtumomab, Oregovomab, CC49 (minretumomab), cG250, J591, MOv18, Farletuzumab (MORAb- 003 ), 3 F 8 , ch 14 . 18 , KW- 2871 , hu 3 S 193 , IgN 311 , Bevacizumab, IM-2C6, CDP791, Etaracizumab, Volociximab, Cetuximab, Panitumumab, Nimotuzumab, 806, Trastuzumab, Pertuzumab, MM-121, AMG 102, METMAB, SCH 900105, AVE1642, IMC-A12, MK-0646, R1507, CP 751871, KB004, IIIA4, Mapatumumab (HGS-ETR1), Lexatumumab (HGS-ETR2), CS-1008, Denosumab, Sibrotuzumab, F19, 8106, humanized anti HER2 mAb, Edrecolomab, Cetuximab, Smart MI95, LymphoCide, Smart ID10, Oncolym, Allomune, or Epratuzamab.

12. The antibody-drug conjugate (ADC) as claimed in claim 7 , wherein the linker unit is a cleavable linker or a noncleavable linker.

13. The antibody-drug conjugate (ADC) as claimed in claim 12 , wherein the cleavable linker comprises a peptide unit (-AAs-) selected from a group consisting of -valline-citruline-(-Val-Cit-), -valline-lysine-(-Val-Lys-), -valline-arginine-(-Val-Arg-), -phenylalanine-citruline-(-Phe-Cit-), -phenylalanine-lysine-(-Phe-Lys-), and -phenylalanine-arginine-(-Phe-Arg-).

14. The antibody-drug conjugate (ADC) as claimed in claim 7 ,

wherein L is linear alkyl, cycloalkyl, heterocycloalkyl, alkenyl, alkynyl, aryl, heteroaryl, poly(ethylene glycol) chain, or a combination thereof; and Do, Dp and Dq are independently cytotoxic drugs, anti-autoimmune disease drugs, or anti-inflammation drugs.

15. The antibody-drug conjugate (ADC) as claimed in claim 7 , wherein the drug unit is amanitins, anthracyclines, auristatins, baccatins, calicheamicins, camptothecins, cemadotins, colchicines, colcimids, combretastatins, cryptophycins, discodermolides, docetaxel, doxorubicin, duocarmycins, echinomycins, eleutherobins, epothilones, estramustines, lexitropsins, maytansines, maytansinoids, methotrexate, netropsins, pyrrolo[2,1-c][1,4]benzodi-azepines (PBDs), puromycins, rhizoxins, SN-38, taxanes, tubulysins, or vinca alkaloids.

16. The antibody-drug conjugate (ADC) as claimed in claim , wherein the average DAR of the antibody-drug conjugate is about 3-8.