Antibody-drug conjugate containing heterocyclic compound having activity of inducing decomposition of KRAS mutant proteins

Abstract

Provided is an antibody-drug conjugate for use in the treatment of cancer in which one or more KRAS mutants, particularly a KRAS G12V mutant, a KRAS G12D mutant, and a KRAS G12C mutant, are expressed. Also provided are a drug and a drug-linker conjugate for use in the antibody-drug conjugate.　The present inventors have produced an antibody-drug conjugate with which a heterocyclic compound represented by formula (II) and having an activity of inducing the decomposition of KRAS mutant proteins can be delivered to cancer in which EGFRs are expressed, the production being achieved by linking the compound to an anti-EGFR antibody. The present inventors have also discovered a drug-linker conjugate for use in the antibody-drug conjugate or a salt thereof. In cancer in which EGFRs are expressed, the antibody-drug conjugate induces the decomposition of one or more KRAS mutants, particularly a KRAS G12V mutant protein, a KRAS G12D mutant protein, and a KRAS G12C mutant protein, thereby inhibiting the KRAS mutants and exhibiting an anti-tumor effect.

Description

Antibody-drug conjugate containing heterocyclic compound having mutant KRAS protein degradation-inducing activity The present invention relates to a heterocyclic compound (hereinafter, the compound may also be referred to as a drug) having the activity of inducing the degradation of mutant KRAS proteins, particularly G12V, G12D, and G12C mutant KRAS proteins, an antibody-drug conjugate or a salt thereof containing the heterocyclic compound, or a pharmaceutical composition containing the antibody-drug conjugate or a salt thereof. The present invention also relates to a drug-linker conjugate or a salt thereof for use in the antibody-drug conjugate or a salt thereof. RAS proteins are small guanosine triphosphate (GTP)-binding proteins of approximately 21 kDa, consisting of 188 or 189 amino acids. There are four major RAS proteins (KRAS (KRAS4A and KRAS4B), NRAS, and HRAS) produced by three genes: KRAS, NRAS, and HRAS. RAS proteins exist in active, GTP-bound forms and inactive, GDP-bound forms. RAS proteins are activated by the exchange of guanosine diphosphate (GDP) for GTP upon ligand stimulation of cell membrane receptors such as EGFR. Active RAS binds to 11 different effector proteins, including RAF, PI3K, and RALGDS, and activates downstream signaling cascades. Active RAS becomes inactive by converting GTP to GDP through its intrinsic GTP hydrolysis (GTPase) activity. This GTPase activity is enhanced by GTPase-activating proteins (GAPs). This indicates that RAS functions as an important "molecular switch" in intracellular signaling pathways such as EGFR, and plays an important role in processes such as cell growth, proliferation, and angiogenesis (Nature Rev. Cancer, 2011, 11, pp. 761-774; Nature Rev. Drug Discov., 2014, 13, pp. 828-851; Nature Rev. Drug Discov., 2016, 15, pp. 771-785). When RAS gene mutations result in amino acid substitutions, RAS becomes constitutively active due to impaired GTPase function and reduced response to GAPs, resulting in continuous downstream signaling. This excessive signaling leads to carcinogenesis and accelerated cancer proliferation. For example, KRAS gene mutations are found in approximately 85% of patients with pancreatic ductal adenocarcinoma, and these mutations are present even in the early stages of pancreatic intraepithelial neoplasia (PanIN). KRAS gene mutations are also frequently found in lung cancer and colorectal cancer. Many known examples of KRAS gene mutations include point mutations at codon 12 located in KRAS exon 2 (KRAS G12C mutation, KRAS G12D mutation, etc.) (Nat Rev Cancer. 2010. 10(10). 683-695, Semin Oncol. 2021. 48(1). 10-18, Nat Rev Cancer. 2018. 18. 767-777). In recent years, bifunctional compounds, collectively known as PROTACs (PROteolysis-TArgeting Chimeras) and SNIPERs (Specific and Nongenetic IAP-dependent Protein Erasers), have been discovered as a technology for inducing targeted protein degradation and are expected to become a novel drug discovery modality (Drug. Discov. Today Technol., 2019, 31, pp. 15-27). These bifunctional compounds promote the formation of complexes between target proteins and E3 ligases, resulting in the ubiquitination of the target proteins, which then induces their degradation via the ubiquitin-proteasome system. The ubiquitin-proteasome system is one of the intracellular protein degradation mechanisms. Proteins called E3 ligases recognize and ubiquitinate proteins to be degraded, leading to their degradation via the proteasome. There are over 600 types of E3 ligases in the body, but only a limited number of E3 ligases have been used in bifunctional degradation inducers, such as PROTACs and SNIPERs, to date. Representative examples include von Hippel-Lindau (VHL), cereblon (CRBN), inhibitor of apoptosis protein (IAP), and mouse double minute 2 homolog (MDM2). These bifunctional compounds are compounds in which a ligand for a target protein and a ligand for E3 ligase are linked via a linker. Patent Documents 1 to 7 describe bifunctional compounds that degrade mutant KRAS proteins. Furthermore, Patent Documents 8 to 10 describe bifunctional compounds that degrade KRAS having a G12D mutation, in which a substituent substituted at the 8th position of quinoline and quinazoline is linked to a ligand for E3 ligase. Furthermore, Patent Documents 11 to 16, which were published after the priority date of the present application, describe bifunctional compounds that degrade mutant KRAS proteins. Meanwhile, research into technologies for selectively delivering drugs to cancer cells is progressing, including antibody-drug conjugates (ADCs), which conjugate cytotoxic drug molecules to antibodies targeting antigens expressed on the surface of cancer cells, and immune-stimulating antibody conjugates (ISACs), which conjugate immunostimulatory drug molecules. Pharmaceuticals using these technologies have been approved (Cancer Science, 2016, Vol. 107, No. 7, pp. 1039-1046; Clinical Cancer Research, 2005, Vol. 11, pp. 843-852; Cancer Research, 2016, Vol. 76, No. 10, pp. 3003-3013). Patent documents 17 to 21 describe ADCs containing bifunctional compounds as drugs that induce degradation of target proteins. Non-patent document 1 describes antibody-based PROTACs (AbTACs) that utilize anti-EGFR antibodies to degrade EGFR. However, to date, no ADCs containing a drug that has the effect of inducing the degradation of mutant KRAS proteins, particularly G12V, G12D, and G12C mutant KRAS proteins, are known. International Publication No. 2023 / 099620 International Publication No. 2023 / 141570 International Publication No. 2022 / 271823 International Publication No. 2023 / 130012 International Publication No. 2022 / 087335 International Publication No. 2022 / 266249 International Publication No. 2023 / 185864 International Publication No. 2022 / 173032 International Publication No. 2023 / 171781 International Publication No. 2024 / 019103 International Publication No. 202 International Publication No. 4 / 118966 International Publication No. 2024 / 119278 International Publication No. 2024 / 120424 International Publication No. 2024 / 083256 International Publication No. 2024 / 029613 International Publication No. 2024 / 034593 International Publication No. 2021 / 195598 International Publication No. 2023 / 056069 International Publication No. 2020 / 086858 International Publication No. 2022 / 020288 International Publication No. 2022 / 220625 Int. J. Biol. Macromol., 252, 126413 (2023) The present invention provides a heterocyclic compound having the activity of inducing the degradation of mutant KRAS proteins, particularly G12V, G12D, and G12C mutant KRAS proteins, an antibody-drug conjugate or a salt thereof containing the heterocyclic compound, and a pharmaceutical composition containing the antibody-drug conjugate or a salt thereof. The present invention also provides a drug-linker conjugate or a salt thereof for use in the antibody-drug conjugate or a salt thereof. The present inventors have conducted extensive research into compounds useful as active ingredients of pharmaceutical compositions, and as a result have found that an antibody-drug conjugate having the structure of formula (I) has excellent mutant KRAS proteolysis-inducing activity, particularly the activity of inducing the degradation of G12V, G12D, and G12C mutant KRAS proteins. They have also found that heterocyclic compounds having mutant KRAS proteolysis-inducing activity, particularly the activity of inducing the degradation of G12V, G12D, and G12C mutant KRAS proteins, and drug-linker conjugates containing such heterocyclic compounds, are useful for synthesizing such antibody-drug conjugates, and have completed the present invention. That is, the present invention relates to the following [0] to [45-2]. [0] An antibody-drug conjugate represented by formula (I') or a salt thereof (In the formula, Ab is an antibody or antigen-binding fragment thereof; D' is a heterocyclic compound that has an activity of inducing RAS protein degradation, L A is a linker for connecting Ab and D, m is a number between 1 and 20). [1] An antibody-drug conjugate represented by formula (I) or a salt thereof (In the formula, Ab is an antibody or antigen-binding fragment thereof; D is a heterocyclic compound that induces the degradation of mutant KRAS proteins, L A is a linker for connecting Ab and D, m is a number between 1 and 20). [2] D is a heterocyclic compound having the activity of inducing mutant KRAS protein degradation represented by formula (II), A is CR A , or N, R A is H or C 1-3 is alkyl, X 1 is —CH— or —O—, R 1 represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R 1a is H, methyl, F or Cl, R 1b is F, Cl, methyl or ethyl, R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 is alkyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII), R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, R 3b is H or C 1-3 is alkyl, R 3c and R 3d is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, However, R 3c -(CH2) p CHR 3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 alkyl)-, R 3e -OC2-3 Alkylene-NR N1 R N2 and R 3f is H, F or C 1-3 is alkyl, R 3g is H or C 1-3 is alkyl, R 3h is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms; R 3i are the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２ , a group selected from the group consisting of halogen, -CN, and oxo; or Two R's on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two adjacent carbon atoms 3i together with the two carbon atoms to form C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C1-3 alkyl), OH, halogen, and oxo; or R on two non-adjacent carbon atoms 3i may form a bridged structure consisting of 1 to 2 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C 1-3 Alkyl, -O-(C 1-3 optionally substituted with 1 to 2 groups selected from the group consisting of alkyl), OH, halogen, and oxo; R N1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2 may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 may form, together with the carbon atom and nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen, X 2 is -O-, -NH-, or -N(C 1-3 alkyl)-, X 3 is O or S, X 4 is -CH2-, -CH2-CH2-, or -O-CH2-, n is 1 or 2, p is 1 or 2; q is an integer from 1 to 8; R 4 F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4apyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4a C optionally substituted with F 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3 is alkyl, Y is phenylene optionally substituted with F or Cl, or pyridinediyl; L P is a group that chemically bonds Y and EUB, EUB is a group capable of binding to E3 ubiquitin ligase, L A is a linker for binding Ab to D, and is bound to any nitrogen atom or oxygen atom of —OH contained in D. When the nitrogen atom is a tertiary amine, the nitrogen atom is bound to L A The antibody-drug conjugate or salt thereof according to [1], which binds to the following to form a quaternary ammonium. [3] L A is a linker for binding Ab to D, and D has a group R 3 , R 4 or NL bonded to the nitrogen atom of the amine or the oxygen atom of -OH contained in EUB A Or office worker A where, if the amine is a tertiary amine, the nitrogen atom of the amine is L A [2] The antibody-drug conjugate or salt thereof according to [2], which binds to the [4] A is CR A , or N, R A is H, X 1 is -O-, R 1is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), and (XI): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, R 3f is H, R N1 and R N2 are the same or different and are H or C 1-3 It is an alkyl X 2 is —O— or —NH—, X 3 is O, n is 1, p is 1, R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 is alkyl, The antibody-drug conjugate or salt thereof according to [3], wherein Y is phenylene. [5] A is N, R 3 is a group represented by the following formula (XI): R 4 is N(R4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3 The antibody-drug conjugate or salt thereof according to [4], wherein the aryl group is alkyl. [6] The antibody-drug conjugate or salt thereof according to [3], wherein EUB is a group capable of binding to VHL. [6-2] The antibody-drug conjugate or salt thereof according to [3], wherein EUB is a group capable of binding to CRBN. [6-3] The antibody-drug conjugate or salt thereof according to [3], wherein EUB is a group capable of binding to VHL or CRBN. [7] EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is methyl, ethyl, isopropyl, isobutyl, sec-butyl, tert-butyl, C 3-6 cycloalkylmethyl, or C 3-6 is cycloalkyl, R 6a and R 6b are the same or different and may be substituted with H or a group selected from the group consisting of OH, OCH3, and N(CH3)2; 1-6 alkyl, or R 6a , R 6b may be substituted together with the carbon to which they are attached. 3-6 It may form a cycloalkane or an optionally substituted 4- to 6-membered saturated heterocycle containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen as ring-constituting atoms, R 7 is an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or a 6-membered heteroaryl containing 1 to 3 nitrogen atoms, W is an optionally substituted phenylene or an optionally substituted 6-membered heteroarenediyl containing 1 to 3 nitrogen atoms as ring-constituting atoms; L P is -(L 1 -L 2 -L 3 -L 4 )- and L 1 , L 2 , L 3 , L 4 are the same or different and represent a bond, -O-, -NR L1 -, optionally substituted pyrrolidinediyl, optionally substituted piperidinediyl, optionally substituted piperazinediyl, optionally substituted C 1-3 a group selected from the group consisting of alkylene and C═O; R L1 is H or C 1-3 is alkyl, The antibody-drug conjugate or salt thereof according to any one of [3] to [5], wherein Z is NH or a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. [8] EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen; W is phenylene; L P is a bond, [7] The antibody-drug conjugate or a salt thereof according to [7], wherein Z is a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. [9] R 7 is a group selected from the group consisting of the following formulae (XIX-a), (XX-a), and (XVI), W is a group represented by the following formula (XVII-a): [8] The antibody-drug conjugate or salt thereof according to [8], wherein Z is a group represented by the following formula (XVIII):

[0010] R 7 is a group represented by the following formula (XVI):

[0011] L A is a linker represented by formula (XV): (In the formula, Str is the stretcher unit, which binds to Ab and CLL; CLL is a partial structure that can be cleaved in vivo. Sp is a spacer unit, which binds to CLL and D, and t is 0 or 1; *Ab indicates the binding site with Ab.

[0012] i) Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 alkylene, -optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - or -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 ​​alkylene-, and a is an integer from 1 to 10; R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-1), *STR indicates the binding site with Str, R AA are each independently a radical selected from the group consisting of H, methyl, isopropyl, benzyl, and —(CH)—NH—C(═O)—NH, d is an integer from 2 to 4, Sp is a spacer unit represented by formula (SP-1), formula (SP-2), or formula (SP-3), t is 1, *CLL indicates the binding site with CLL, R SP is H, Or, ii) Str is a stretcher unit represented by formula (ST-1), and r is 1; *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEGis -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-2), *STR indicates the binding site with Str, The antibody-drug conjugate or salt thereof according to

[0011] , wherein t is 0.

[0013] Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-2), *STR indicates the binding site with Str, The antibody-drug conjugate or salt thereof according to

[0012] , wherein t is 0.

[0014] A is CR A , or N, R A is H,​​ X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), and (XI): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, R 3f is H, R N1 and R N2 are the same or different and are H or C 1-3 It is an alkyl X 2 is —O— or —NH—, X 3 is O, n is 1, p is 1, R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 is alkyl, Y is phenylene; EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen; W is phenylene; L P is a bond, Z is a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms; L A is a linker represented by formula (XV) *Ab indicates the binding site with Ab), Str is the stretcher unit, which binds to Ab and CLL; CLL is a partial structure that can be cleaved in vivo. Sp is a spacer unit, which binds to CLL and D, and t is 0 or 1; where: i) Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 alkylene, -optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - or -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 alkylene-, and a is an integer from 1 to 10; R PEG is -(CH2CH2O) b -CH3, -C(=O)-C1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-1), *STR indicates the binding site with Str, R AA are each independently a radical selected from the group consisting of H, methyl, isopropyl, benzyl, and —(CH)—NH—C(═O)—NH, d is an integer from 2 to 4, Sp is a spacer unit represented by formula (SP-1), formula (SP-2) or formula (SP-3), t is 1, *CLL indicates the binding site with CLL, R SP is H, Or, ii) Str is a stretcher unit represented by formula (ST-1), and r is 1; *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b-CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-2), *STR indicates the binding site with Str, t is 0, L A is the group R 3 or R 4 or the oxygen atom of -OH in EUB. A Or office worker A where, if the amine is a tertiary amine, the nitrogen atom of the amine is L A combines with to form a quaternary ammonium The antibody-drug conjugate or salt thereof according to [3], wherein m is a number between 2 and 10.

[0015] A is N, R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3 is alkyl, R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): Z is a group represented by the following formula (XVIII): Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 ​Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-2), *STR indicates the binding site with Str, t is 0, L A is R 4 N(R 4a )2 is bonded to the nitrogen atom - N + (R 4a )2-L A The antibody-drug conjugate or salt thereof according to

[0014] , which forms: [15-2] A is N, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3 is alkyl, Y is phenylene; L P is a bond, EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): The antibody-drug conjugate or salt thereof according to [3], wherein Z is a group represented by the following formula (XVIII): [15-3] A is CR A , or N, R A is H, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group selected from the group consisting of the following formula (IV-a) and formula (Va): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, R 3f is H, R N1 and R N2are the same or different and are H or C 1-3 is alkyl, X 2 is —O— or —NH—, X 3 is O, p is 1, R 4 C may be substituted with OCH3 1-6 is alkyl, Y is phenylene; L P is a bond, EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl, R 6a is H and R 6b is hydroxymethyl, R 7 is a group selected from the group consisting of the following formula (XIX-a) and formula (XVI), W is a group represented by formula (XVII-a), [3] The antibody-drug conjugate or salt thereof according to [3], wherein Z is a group represented by the following formula (XVIII-a): (In the formula, * is L P ) indicates the connection point with . [15-4] L A is a linker represented by formula (XV) *Ab indicates the binding site with Ab), Str is a stretcher unit that binds to Ab and CLL, r is 0, CLL is a partial structure that can be cleaved in vivo and is represented by the formula (CL-3). (In the formula, *STR indicates the binding site with Str), Sp is a spacer unit represented by formula (SP-4) (In the formula, *CLL indicates the binding site to CLL. ), binds to CLL and D, t is 1, L A is bonded to the oxygen atom of -OH contained in EUB to form OL A The antibody-drug conjugate or salt thereof according to [3], which forms:

[0016] The antibody-drug conjugate or salt thereof according to [3], represented by the following formula (AD-1), (AD-2), or (AD-3): (wherein b is an integer from 2 to 20, and m is a number from 2 to 10).

[0017] The antibody-drug conjugate or salt thereof according to

[0016] , wherein b is 12 and m is a number from 3 to 9.

[0018] Ab, 5T4, ADAM9, ALPP, ALPPL2, AXL, B7H3, B7H4, BCMA, CA9, CCR2, CCR7, CD123, CD166, CD19, CD20, CD22, CD25, CD30, CD33, CD37, CD38, CD45, CD4 6, CD70, CD74, CD79b, CDH3, CDH6, CEACAM5, CEACAM6, CLDN1, CLDN4, CLDN6, CLDN18.2, cMET, EGFR, EphA3, FAP, FGFR3, Fibronectin, FOLRa, Globo H, GPRC5D, HER2, HER3, IGF1R, Integrin The antibody-drug conjugate or salt thereof according to any one of [1] to

[0017] , which is an antibody or antigen-binding fragment that binds to an antigen selected from the group consisting of αV, KAAG1, LIV1, MSLN, MT1-MMP, MUC1, MUC4, NaPi2b, Nectin-4, PD-L1, PSMA, PTK7, ROR1, ROR2, SEZ6, SialylTn, TF, TROP2, TSPAN8, and VEGF.

[0019] ​​​​The antibody-drug conjugate or salt thereof according to any one of [1] to

[0017] , wherein Ab is an antibody or antigen-binding fragment that binds to an antigen selected from the group consisting of EGFR, HER2, Nectin-4, and TROP2.

[0020] The antibody-drug conjugate or salt thereof according to any one of [1] to

[0017] , wherein Ab is an anti-EGFR antibody or an antigen-binding fragment thereof.

[0021] The antibody-drug conjugate or salt thereof according to

[0020] , wherein Ab is an anti-EGFR antibody or an antigen-binding fragment thereof comprising the heavy chain variable region and light chain variable region described in the following (1) or (2): (1) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 31 to 35 of SEQ ID NO: 1, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 65 of SEQ ID NO: 1, and CDR3 consisting of the amino acid sequence from amino acid numbers 98 to 108 of SEQ ID NO: 1; and a light chain variable region comprising a CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 2, a CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 2, and a CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 2; or (2) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 3, CDR2 consisting of the amino acid sequence of amino acids 50 to 65 of SEQ ID NO: 3, and CDR3 consisting of the amino acid sequence of amino acids 98 to 108 of SEQ ID NO: 3; and A light chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 4, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 4.

[0022] The antibody-drug conjugate or salt thereof according to

[0021] , wherein Ab is an anti-EGFR antibody or an antigen-binding fragment thereof comprising a heavy chain variable region and a light chain variable region selected from the group consisting of the following (1) to (3): ​​​(1) a heavy chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 119 of SEQ ID NO: 1 and a light chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 107 of SEQ ID NO: 2; (2) a heavy chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 119 of SEQ ID NO: 3 and a light chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 107 of SEQ ID NO: 4; and (3) A heavy chain variable region and a light chain variable region having at least 90% identity to the heavy chain variable region and the light chain variable region described in (1) or (2) above.

[0023] The antibody-drug conjugate or salt thereof according to

[0022] , wherein Ab is an IgG1 or IgG4 type anti-EGFR antibody.

[0024] The antibody-drug conjugate or salt thereof according to

[0023] , wherein Ab is cetuximab.

[0025] An antibody-drug conjugate or a salt thereof described in

[0023] , wherein Ab is an anti-EGFR antibody consisting of a heavy chain of sequence number 1 and a light chain of sequence number 2.

[0026] The antibody-drug conjugate or salt thereof according to any one of

[0018] to

[0025] , wherein the Ab is an antibody or antigen-binding fragment that has been post-translationally modified or in which any amino acid residue has been substituted with cysteine or a non-natural amino acid.

[0027] An antibody-drug conjugate represented by formula (I) or a salt thereof (In the formula, The Ab is an anti-EGFR antibody or an antigen-binding fragment thereof comprising a heavy chain variable region and a light chain variable region described in (1) or (2) below: (1) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 31 to 35 of SEQ ID NO: 1, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 65 of SEQ ID NO: 1, and CDR3 consisting of the amino acid sequence from amino acid numbers 98 to 108 of SEQ ID NO: 1; and ​​​​​a light chain variable region comprising a CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 2, a CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 2, and a CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 2; or (2) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 3, CDR2 consisting of the amino acid sequence of amino acids 50 to 65 of SEQ ID NO: 3, and CDR3 consisting of the amino acid sequence of amino acids 98 to 108 of SEQ ID NO: 3; and a light chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 4, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 4; L A is a linker represented by formula (LA-3) ( *Ab indicates the binding site with Ab), b is 12, D is a heterocyclic compound having an activity of inducing the degradation of mutant KRAS protein, represented by formula (PL-1') (wherein: *LA is L A (representing the bond with m is a number between 3 and 9). [27-2] Ab is an anti-EGFR antibody or an antigen-binding fragment thereof comprising a heavy chain variable region and a light chain variable region described in (1) or (2) below: (1) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 31 to 35 of SEQ ID NO: 1, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 65 of SEQ ID NO: 1, and CDR3 consisting of the amino acid sequence from amino acid numbers 98 to 108 of SEQ ID NO: 1; and a light chain variable region comprising a CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 2, a CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 2, and a CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 2; or (2) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 3, CDR2 consisting of the amino acid sequence of amino acids 50 to 65 of SEQ ID NO: 3, and CDR3 consisting of the amino acid sequence of amino acids 98 to 108 of SEQ ID NO: 3; and a light chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 4, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 4; L A is a linker represented by formula (XV) *Ab indicates the binding site with Ab), Str is the stretcher unit, which binds to Ab and CLL; CLL is a partial structure that can be cleaved in vivo. Sp is a spacer unit, which binds to CLL and D, and t is 0 or 1; D is a heterocyclic compound represented by formula (TP-1), (TP-2) or (TP-3) and having an activity of inducing mutant KRAS protein degradation, A is CR A , or N, R A is H or C 1-3 is alkyl, X 1 is —CH— or —O—, R 1 represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R 1a is H, methyl, F or Cl, R 1b is F, Cl, methyl or ethyl, R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 is alkyl, R3 is a group selected from the group consisting of the following formulas (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII), R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, R 3b is H or C 1-3 is alkyl, R 3c and R 3d is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2, and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, However, R 3c -(CH2) p CHR 3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 alkyl)-, R 3e -OC 2-3 Alkylene-NR N1 R N2 and R 3f is H, F or C 1-3 is alkyl, R 3g is H or C 1-3 is alkyl, R 3h is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms; R 3i are the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２, a group selected from the group consisting of halogen, -CN, and oxo; or Two R's on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two adjacent carbon atoms 3i together with the two carbon atoms to form C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two non-adjacent carbon atoms 3i may form a bridged structure consisting of 1 to 2 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C 1-3 Alkyl, -O-(C 1-3 optionally substituted with 1 to 2 groups selected from the group consisting of alkyl), OH, halogen, and oxo; R N1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 may form, together with the carbon atom and nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen, X 2 is -O-, -NH-, or -N(C 1-3 alkyl)-, X 3 is O or S, X 4 is -CH2-, -CH2-CH2-, or -O-CH2-, n is 1 or 2, p is 1 or 2; q is an integer from 1 to 8; R 4 are F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4a pyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4a C optionally substituted with F 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3 is alkyl, Y is phenylene optionally substituted with F or Cl, or pyridinediyl; L P is a group that chemically bonds Y and EUB, EUB is a group capable of binding to E3 ubiquitin ligase, R 8

[0023] The antibody-drug conjugate or salt thereof according to [1], wherein [27-3] The antibody-drug conjugate or salt thereof according to [27-2], wherein D is a heterocyclic compound having the activity of inducing the degradation of mutant KRAS protein, represented by formula (TP-1). [27-4] The antibody-drug conjugate or salt thereof according to [27-2], wherein D is a heterocyclic compound having the activity of inducing mutant KRAS protein degradation represented by formula (TP-2). [27-5] An antibody-drug conjugate or a salt thereof according to [27-2], wherein D is a heterocyclic compound having the activity of inducing the degradation of mutant KRAS protein, represented by formula (TP-3).

[0028] A pharmaceutical composition comprising the antibody-drug conjugate or salt thereof according to any one of [1] to

[0027] and a pharmaceutically acceptable excipient.

[0029] A pharmaceutical composition described in

[0028] for use in the treatment of cancer.

[0030] The pharmaceutical composition described in

[0029] , wherein the cancer is a blood cancer or a solid cancer.

[0031] The pharmaceutical composition described in

[0029] , wherein the cancer is colon cancer, pancreatic cancer, or lung cancer.

[0032] The pharmaceutical composition described in

[0029] , wherein the cancer is a cancer that expresses mutant KRAS.

[0033] The pharmaceutical composition described in

[0032] , wherein the mutated KRAS is any one of G12V mutation, G12D mutation, and G12C mutation KRAS.

[0034] An antibody-drug conjugate or a salt thereof according to any one of [1] to

[0027] for use in the treatment of cancer.

[0035] A method for treating cancer, comprising the step of administering a therapeutically effective amount of the antibody-drug conjugate or salt thereof according to any one of [1] to

[0027] to a subject.

[0036] ​​​​​​​​​Use of an antibody-drug conjugate or a salt thereof according to any one of [1] to

[0027] in the manufacture of a pharmaceutical composition for the treatment of cancer.

[0037] A drug-linker conjugate represented by formula (LD-1) or a salt thereof (In the formula, D is a heterocyclic compound that induces the degradation of mutant KRAS proteins, R st1 may be substituted C 1-12 Alkylene or optionally substituted C 1-50 is heteroalkylene, CLL is a partial structure that can be cleaved in vivo. Sp is a spacer unit and binds to CLL and D; t is 0 or 1; Sp bonds to the nitrogen atom of the amine or the oxygen atom of -OH in D to form N-Sp or O-Sp, where if the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium).

[0038] D is a heterocyclic compound represented by formula (II) having an activity of inducing mutant KRAS protein degradation, A is CR A , or N, R A is H or C 1-3 is alkyl, X 1 is —CH— or —O—, R 1 represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R 1a is H, methyl, F or Cl, R 1b is F, Cl, methyl or ethyl, R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 is alkyl, R​​3 is a group selected from the group consisting of the following formulas (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII), R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, R 3b is H or C 1-3 is alkyl, R 3c and R 3d is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2, and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, However, R 3c -(CH2) p CHR 3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 alkyl)-, R 3e -OC 2-3 Alkylene-NR N1 R N2 and R 3f is H, F or C 1-3 is alkyl, R 3g is H or C 1-3 is alkyl, R 3h is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms; R 3i are the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２, a group selected from the group consisting of halogen, -CN, and oxo; or Two R's on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two adjacent carbon atoms 3i together with the two carbon atoms to form C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two non-adjacent carbon atoms 3i may form a bridged structure consisting of 1 to 2 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C 1-3 Alkyl, -O-(C 1-3 optionally substituted with 1 to 2 groups selected from the group consisting of alkyl), OH, halogen, and oxo; R N1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 may form, together with the carbon atom and nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen, X 2 is -O-, -NH-, or -N(C 1-3 alkyl)-, X 3 is O or S, X 4 is -CH2-, -CH2-CH2-, or -O-CH2-, n is 1 or 2, p is 1 or 2; q is an integer from 1 to 8; R 4 F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4a pyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4a C optionally substituted with F 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3 is alkyl, Y is phenylene optionally substituted with F or Cl, or pyridinediyl; L P is a group that chemically bonds Y and EUB, EUB is a group capable of binding to E3 ubiquitin ligase, CLL is a partial structure that can be cleaved in vivo. Sp is a spacer unit, which binds to CLL and D, and t is 0 or 1; Sp is a group R carried by D. 3 , R 4 or bonded to the nitrogen atom of an amine or the oxygen atom of -OH contained in EUB to form N-Sp or O-Sp, wherein when the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium; where: i) R st1 may be substituted C 1-12 alkylene, -optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - or -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 alkylene-, and a is an integer from 1 to 10; R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure represented by formula (CL-1') that can be cleaved in vivo, *CO indicates the bond to the carbonyl group, R AA are each independently a radical selected from the group consisting of H, methyl, isopropyl, benzyl, and —(CH)—NH—C(═O)—NH, d is an integer from 2 to 4, Sp is a spacer unit represented by formula (SP-1), formula (SP-2) or formula (SP-3), t is 1,*CLL indicates the binding site with CLL, R SP is H, Or, ii) R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure represented by formula (CL-2') that can be cleaved in vivo, *CO indicates the bond to the carbonyl group, A drug-linker conjugate or a salt thereof according to

[0037] , wherein t is 0.

[0039] EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is methyl, ethyl, isopropyl, isobutyl, sec-butyl, tert-butyl, C 3-6 cycloalkylmethyl, or C 3-6 is cycloalkyl, R 6a and R 6b ​are the same or different and may be substituted with H or a group selected from the group consisting of OH, OCH3, and N(CH3)2; 1-6 alkyl, or R 6a , R 6b may be substituted together with the carbon to which they are attached. 3-6 It may form a cycloalkane or an optionally substituted 4- to 6-membered saturated heterocycle containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen as ring-constituting atoms, R 7 is an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or a 6-membered heteroaryl containing 1 to 3 nitrogen atoms, W is an optionally substituted phenylene or an optionally substituted 6-membered heteroarenediyl containing 1 to 3 nitrogen atoms as ring-constituting atoms; L P is -(L 1 -L 2 -L 3 -L 4 )- and L 1 , L 2 , L 3 , L 4 are the same or different and represent a bond, -O-, -NR L1 -, optionally substituted pyrrolidinediyl, optionally substituted piperidinediyl, optionally substituted piperazinediyl, optionally substituted C 1-3 a group selected from the group consisting of alkylene and C═O; R L1 is H or C 1-3 is alkyl, The drug-linker conjugate or salt thereof according to

[0038] , wherein Z is NH or a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. ​

[0040] A is CR A , or N, R A is H, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), and (XI): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, R 3f is H, R N1 and R N2 are the same or different and are H or C 1-3 It is an alkyl X 2 is —O— or —NH—, X 3 is O, n is 1, p is 1, R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 is alkyl, The drug-linker conjugate or salt thereof according to

[0039] , wherein Y is phenylene.

[0041] EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen; W is phenylene; L P is a bond, Z is a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms; Sp is a group R carried by D. 3 or R 4 or the oxygen atom of —OH contained in EUB to form N-Sp or O-Sp, and when the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium.

[0042] A is N, R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3 is alkyl, R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a):​ Z is a group represented by the following formula (XVIII): R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure represented by formula (CL-2') that can be cleaved in vivo, *CO indicates the bond to the carbonyl group, t is 0, Sp is a group R carried by D. 4 N(R 4a )2 bonded to the nitrogen atom -N + (R 4a )2-Sp is formed, or a salt thereof, of the drug-linker conjugate according to

[0041] .

[0043] A drug-linker conjugate or a salt thereof according to

[0037] , represented by the following formula (LD-2), (LD-3) or (LD-4): (wherein b is an integer from 2 to 20).

[0044] A drug-linker conjugate or a salt thereof according to

[0043] , wherein b is 12. [44-2] A drug-linker conjugate represented by formula (LD-8) or a salt thereof​​ (In the formula, D is a heterocyclic compound represented by formula (II) having an activity of inducing mutant KRAS protein degradation, A is CR A , or N, R A is H or C 1-3 is alkyl, X 1 is —CH— or —O—, R 1 represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R 1a is H, methyl, F or Cl, R 1b is F, Cl, methyl or ethyl, R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 is alkyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII), R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of:1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, R 3b is H or C 1-3 is alkyl, R 3c and R 3d is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, However, R 3c -(CH2) p CHR 3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 alkyl)-, R 3e -OC 2-3 Alkylene-NR N1 R N2 and R 3f is H, F or C 1-3 is alkyl, R 3g is H or C 1-3 is alkyl, R 3h is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms; R 3i are the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２ , a group selected from the group consisting of halogen, -CN, and oxo; or Two R's on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two adjacent carbon atoms 3i together with the two carbon atoms to form C 3-6A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two non-adjacent carbon atoms 3i may form a bridged structure consisting of 1 to 2 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C 1-3 Alkyl, -O-(C 1-3 optionally substituted with 1 to 2 groups selected from the group consisting of alkyl), OH, halogen, and oxo; R N1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2 may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 may form, together with the carbon atom and nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen, X 2 is -O-, -NH-, or -N(C 1-3 alkyl)-, X 3 is O or S, X 4 is -CH2-, -CH2-CH2-, or -O-CH2-, n is 1 or 2, p is 1 or 2; q is an integer from 1 to 8; R 4 F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4a pyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4a C optionally substituted with F 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3 is alkyl, Y is phenylene optionally substituted with F or Cl, or pyridinediyl; L P is a group that chemically bonds Y and EUB, EUB is a group capable of binding to E3 ubiquitin ligase, CLL is a partial structure that can be cleaved in vivo and is represented by the formula (CL-3). (In the formula, *STR indicates the binding site with Str), Sp is a spacer unit represented by formula (SP-4) (In the formula, *CLL indicates the binding site to CLL. ), binds to CLL and D, t is 1, Sp bonds to the oxygen atom of —OH contained in the group EUB of D to form O—Sp). [44-3] D is a heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by formula (II), A is N, X 1 is -O-, R1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3 is alkyl, Y is phenylene; L P is a bond, EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): A drug-linker conjugate or a salt thereof according to

[0037] , wherein Z is a group represented by the following formula (XVIII):

[0045] ​(4R)-1-[(2S)-2-{4-[4-({[(7M)-4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-2-[3-(dimethylamino)-2,2-dimethylpropoxy]-7-(6-fluoro-5-methyl-1H-indazol-4-yl)quinazolin-8-yl]oxy}methyl)phenyl]-1H-1,2,3-triazol-1-yl}-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, (4R)-1-[(2S)-2-(4-{4-[({(7M)-4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-[(oxan-4-yl)oxy]quinazolin-8-yl}oxy)methyl]phenyl}-1H-1,2,3-triazol-1-yl)-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, (4R)-1-[(2S)-2-{4-[4-({[(7M)-4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-{[(3R)-1-methylpyrrolidin-3-yl]methoxy}quinazolin-8-yl]oxy}methyl)phenyl]-1H-1,2,3-triazol-1-yl}-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, and (4R)-1-[(2S)-2-(4-{4-[({(7M)-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-[(2S)-2-methoxypropoxy]-4-[(1-{[2-(methylamino)ethyl]carbamoyl}azetidin-3-yl)oxy]quinolin-8-yl}oxy)methyl]phenyl}-1H-1,2,3-triazol-1-yl)-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide A heterocyclic compound or a salt thereof having an activity of inducing mutant KRAS protein degradation, selected from the group consisting of: [45-2] (4R)-1-[(2S)-2-{4-[4-({[4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-2-[3-(dimethylamino)-2,2-dimethylpropoxy]-7-(6-fluoro-5-methyl-1H-indazol-4-yl)quinazolin-8-yl]oxy}methyl)phenyl]-1H-1,2,3-triazol-1-yl}-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, (4R)-1-[(2S)-2-(4-{4-[({4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-[(oxan-4-yl)oxy]quinazolin-8-yl}oxy)methyl]phenyl}-1H-1,2,3-triazol-1-yl)-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, (4R)-1-{(2S)-2-[4-(4-{[(4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-{[(3R)-1-methylpyrrolidin-3-yl]methoxy}quinazolin-8-yl)oxy]methyl}phenyl)-1H-1,2,3-triazol-1-yl]-3-methylbutanoyl}-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, and (4R)-1-[(2S)-2-(4-{4-[({6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-[(2S)-2-methoxypropoxy]-4-[(1-{[2-(methylamino)ethyl]carbamoyl}azetidin-3-yl)oxy]quinolin-8-yl}oxy)methyl]phenyl}-1H-1,2,3-triazol-1-yl)-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide A heterocyclic compound or a salt thereof having an activity of inducing mutant KRAS protein degradation, selected from the group consisting of: Unless otherwise specified, when a symbol in a chemical formula in this specification is used in other chemical formulas, the same symbol has the same meaning. The antibody-drug conjugate of formula (I) or a salt thereof and the heterocyclic compound of formula (II) or a salt thereof have the activity of inducing mutant KRAS proteolysis, particularly the activity of inducing G12V-, G12D-, and G12C-mutated KRAS proteolysis, and can be used as a therapeutic agent for cancer, particularly cancer expressing mutant KRAS, particularly G12V-, G12D-, and G12C-mutated KRAS. Furthermore, the drug-linker conjugate of the present invention comprises a compound having the activity of inducing mutant KRAS proteolysis, particularly the activity of inducing G12V-, G12D-, and G12C-mutated KRAS proteolysis, and can be used to synthesize the antibody-drug conjugate of the present invention or a salt thereof. The present invention will be described in detail below. In this specification, "optionally substituted" means unsubstituted or having 1 to 5 substituents. In one embodiment, it means unsubstituted or having 1 to 3 substituents. When multiple substituents are present, the substituents may be the same or different from each other. "C 1-12 The term "alkyl" refers to a straight-chain or branched alkyl having 1 to 12 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, dodecyl, etc. (Hereinafter, the number of carbon atoms will be expressed in the same manner.) In one embodiment, it is ethyl or dodecyl. Similarly, "C 1-6 The term "alkyl" refers to a straight-chain or branched alkyl having 1 to 6 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, or n-hexyl, in one embodiment, methyl, ethyl, n-propyl, isopropyl, or sec-butyl, in one embodiment, methyl, ethyl, isopropyl, or tert-butyl, and in one embodiment, methyl, ethyl, n-propyl, isopropyl, or n-butyl. Similarly, "C 1-3 The term "alkyl" refers to a straight-chain or branched alkyl having 1 to 3 carbon atoms, for example, methyl, ethyl, n-propyl, or isopropyl, and in one embodiment, it is methyl or ethyl, in one embodiment, n-propyl or isopropyl, in one embodiment, methyl or isopropyl, in one embodiment, ethyl or isopropyl, in one embodiment, methyl, in one embodiment, ethyl, in one embodiment, isopropyl, or in one embodiment, n-propyl. Similarly, "C 2-3 The term "alkyl" refers to a straight-chain or branched alkyl having 2 to 3 carbon atoms, such as ethyl, n-propyl, or isopropyl, and in one embodiment, it is ethyl, in one embodiment, isopropyl, and in one embodiment, n-propyl. "C 3-6"Cycloalkyl" refers to cycloalkyl having 3 to 6 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. In one embodiment, it is cyclobutyl, cyclopentyl, or cyclohexyl, in one embodiment, cyclobutyl or cyclopentyl, in one embodiment, cyclopentyl or cyclohexyl, in one embodiment, cyclopropyl or cyclobutyl, in one embodiment, cyclopropyl, in one embodiment, cyclobutyl, in one embodiment, cyclopentyl, and in one embodiment, cyclohexyl. "C 1-12 "Alkylene" means C 1-12 A divalent group formed by removing a hydrogen atom from an alkyl, and is a straight-chain or branched C 1-12 Alkylene, for example, methylene, ethylene, trimethylene, methylmethylene, methylethylene, 1,1-dimethylmethylene, pentamethylene, etc. In one embodiment, a linear or branched C 1-6 alkylene, and in one embodiment, a straight-chain or branched C 1-3 In one embodiment, it is alkylene, and in one embodiment, it is methylene, ethylene, or trimethylene, and in one embodiment, it is methylene or ethylene, and in one embodiment, it is methylene, and in one embodiment, it is ethylene. 2-3 "Alkylene" means C 2-3 A divalent group formed by removing a hydrogen atom from an alkyl, and is a straight-chain or branched C 2-3 Alkylene, for example, ethylene, trimethylene, methylmethylene, methylethylene, 1,1-dimethylmethylene, etc. In one embodiment, it is ethylene or trimethylene, in another embodiment, it is ethylene, and in another embodiment, it is trimethylene. "Heteroalkylene" refers to a straight or branched chain alkyl group in which at least one carbon atom is replaced with a heteroatom selected from the group consisting of oxygen, sulfur, and nitrogen. 1-50 Heteroalkylene refers to a C alkylene in which at least one carbon atom is replaced with a heteroatom selected from the group consisting of oxygen, sulfur, and nitrogen. 1-50 alkylene, C 1-6Heteroalkylene refers to a C alkyl group in which at least one carbon atom is replaced with a heteroatom selected from the group consisting of oxygen, sulfur, and nitrogen. 1-6 It is alkylene. A "saturated heterocyclic group" is a saturated hydrocarbon ring group containing a heteroatom selected from the group consisting of oxygen, sulfur, and nitrogen as a ring-constituting atom. In addition, the sulfur atom as a ring-constituting atom of the saturated heterocyclic group may be oxidized. Therefore, a "4- to 6-membered saturated heterocyclic group" is a 4- to 6-membered saturated heterocyclic group containing, as a ring-constituting atom, a heteroatom selected from the group consisting of oxygen, sulfur, and nitrogen. One embodiment of the "4- to 6-membered saturated heterocyclic group" is a 4- to 6-membered saturated heterocyclic group containing, as a ring-constituting atom, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen.In one embodiment of the 4- to 6-membered saturated heterocyclic group containing one or two heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, the group is a 4- to 6-membered saturated heterocyclic group containing one heteroatom selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, and in another embodiment, a 5- to 6-membered saturated heterocyclic group containing one or two heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, and in another embodiment, a heteroatom selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. In one embodiment, it is a 4-membered saturated heterocyclic group containing one or two heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, and in one embodiment, it is a 5-membered saturated heterocyclic group containing one or two heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, and in one embodiment, it is a 6-membered saturated heterocyclic group containing one or two heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, and in one embodiment, it is an oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, azetidinyl, pyrrolidinyl, piperidinyl, oxazolidinyl, imidazolidinyl, piperazinyl, In one embodiment, it is oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, thiomorpholinyl, or dioxothiomorpholinyl, in one embodiment it is oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, pyrrolidinyl, piperidinyl, or morpholinyl, in one embodiment it is oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, pyrrolidinyl, piperidinyl, or morpholinyl, in one embodiment it is oxetanyl, tetrahydrofuranyl, tetrahydropyranyl, In one embodiment, it is oxetanyl, tetrahydrofuranyl, or tetrahydropyranyl, in one embodiment it is pyrrolidinyl or piperidinyl, in one embodiment it is oxetanyl, in one embodiment it is tetrahydrofuranyl, in one embodiment it is tetrahydropyranyl, in one embodiment it is pyrrolidinyl, in one embodiment it is piperidinyl, in one embodiment it is morpholinyl, and in one embodiment it is oxazolidinyl. "Heteroaryl" refers to an aromatic hydrocarbon ring group containing a heteroatom selected from the group consisting of oxygen, sulfur, and nitrogen as a ring member. Thus, a "5-membered heteroaryl" is a 5-membered aromatic hydrocarbon ring group containing from 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. In one embodiment, the "5-membered heteroaryl" is a 5-membered aromatic hydrocarbon ring group containing 1 to 3 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, and in one embodiment, it is pyrazolyl, imidazolyl, triazolyl, tetrazolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, oxadiazolyl, or thiadiazolyl, in one embodiment, it is pyrazolyl, imidazolyl, triazolyl, oxazolyl, or thiazolyl, and in one embodiment, it is pyrazolyl, imidazolyl, oxazolyl, or thiazolyl. In one embodiment, it is pyrazolyl, imidazolyl, triazolyl, or isoxazolyl, in one embodiment, pyrazolyl, oxazolyl, or thiazolyl, in one embodiment, pyrazolyl, triazolyl, or isoxazolyl, in one embodiment, pyrazolyl or thiazolyl, in one embodiment, pyrazolyl or triazolyl, in one embodiment, pyrazolyl, in one embodiment, imidazolyl, in one embodiment, oxazolyl, in one embodiment, thiazolyl, and in one embodiment, triazolyl. Note that "5-membered heteroarenediyl" is a divalent group obtained by removing any one hydrogen atom from "5-membered heteroaryl." A "6-membered heteroaryl" is a 6-membered aromatic hydrocarbon ring group containing 1 to 3 nitrogen atoms as ring-constituting atoms. In one embodiment, the "6-membered heteroaryl" is pyridyl, pyrimidinyl, pyrazinyl, pyridazinyl, or triazinyl, in another embodiment, pyridyl or pyridazinyl, in another embodiment, pyridyl or pyrimidinyl, in another embodiment, pyridyl, or in another embodiment, pyrimidinyl. Note that a "6-membered heteroarenediyl" is a divalent group obtained by removing any one hydrogen atom from a "6-membered heteroaryl." "C 3-6 "Cycloalkane" refers to a cycloalkane having 3 to 6 carbon atoms, such as cyclopropane, cyclobutane, cyclopentane, and cyclohexane. A "saturated heterocycle" is a saturated hydrocarbon ring containing a heteroatom selected from the group consisting of oxygen, sulfur, and nitrogen as a ring-constituting atom. The sulfur atom of the saturated heterocycle may be oxidized. Therefore, a "4- to 6-membered saturated heterocycle" is a 4- to 6-membered saturated hydrocarbon ring containing a heteroatom selected from the group consisting of oxygen, sulfur, and nitrogen as a ring-constituting atom. The sulfur atom of the saturated heterocycle may be oxidized. One embodiment of a "4- to 6-membered saturated heterocycle" is a 4- to 6-membered saturated heterocycle containing one or two heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. One embodiment of a "4- to 6-membered saturated heterocycle" is oxetane, tetrahydrofuran, tetrahydropyran, azetidine, pyrrolidine, piperidine, oxazolidine, imidazolidine, piperazine, morpholine, thiomorpholine, or dioxothiomorpholine. A "spirocycle" is a polycyclic ring structure in which two ring structures are joined by sharing a spiro atom, which is a quaternary carbon. A "bridged ring" is a ring structure having a divalent chain structure connecting two non-adjacent ring-constituting atoms of a single ring. An embodiment of a "bridged ring" is azabicyclo[3.2.1]octane, azabicyclo[3.1.1]heptane, azabicyclo[2.2.1]heptane, or azaoxabicyclo[3.2.1]octane. "Halogen" means F, Cl, Br, and I. In one embodiment, it is F, Cl, or Br, in another embodiment, it is F or Cl, in another embodiment, it is F or Br, in another embodiment, it is F, in another embodiment, it is Cl, and in another embodiment, it is Br. "Optionally substituted C 1-6 "Alkyl" and "Optionally substituted C 1-3 Some embodiments of the substituents permitted for "alkyl" include F, OH, OCH3, N(CH3)2, optionally substituted C 3-6It is a cycloalkyl, azabicyclo[3.3.0]octanyl, or an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen. In one embodiment, it is F, OH, OCH3, N(CH3)2, hydroxymethyl, methoxymethyl, difluoroethyl, optionally substituted cyclopropyl, tetrahydrofuranyl, optionally substituted tetrahydropyranyl, morpholinyl, optionally substituted pyrrolidinyl, optionally substituted piperidinyl, or azabicyclo[3.3.0]octanyl. In another embodiment, it is F, OH, OCH3, N(CH3)2, hydroxymethyl, methoxymethyl, optionally substituted cyclopropyl, tetrahydrofuranyl, optionally substituted tetrahydropyranyl, or optionally substituted pyrrolidinyl. In another embodiment, it is F, OH, OCH3, N(CH3)2, hydroxymethyl, methoxymethyl, optionally substituted cyclopropyl, tetrahydrofuranyl, optionally substituted tetrahydropyranyl, or optionally substituted pyrrolidinyl. In some embodiments, the aryl is cyclopropyl, cyclopropyl, (hydroxymethyl)cyclopropyl, (methoxymethyl)cyclopropyl, tetrahydrofuranyl, tetrahydropyranyl, (hydroxymethyl)tetrahydropyranyl, (methoxymethyl)tetrahydropyranyl, pyrrolidinyl, or methylpyrrolidinyl; in some embodiments, the aryl is F, OH, OCH3, (methoxymethyl)cyclopropyl, tetrahydrofuranyl, or methylpyrrolidinyl; in some embodiments, the aryl is F, OH, or cyclopropyl; in some embodiments, the aryl is F, OH, or OCH3; in some embodiments, the aryl is OH or OCH3; in some embodiments, the aryl is F or OCH3; in some embodiments, the aryl is OH; in some embodiments, the aryl is F; and in some embodiments, the aryl is OCH3. "Optionally substituted 5-membered heteroaryl", "optionally substituted 6-membered heteroaryl", "optionally substituted 6-membered heteroarenediyl", "optionally substituted C 3-6 One embodiment of the acceptable substituents for "cycloalkyl," "optionally substituted pyrazolyl," "optionally substituted pyridyl," "optionally substituted pyrimidinyl," "optionally substituted phenylene," and "optionally substituted cyclopropyl" includes C-substituted phenylenes, which are optionally substituted with a group selected from the group consisting of OH and OCH3.1-3 Alkyl, -SO2CH3, halogen, OH, OCH3, or C 3-6 In one embodiment, a C alkyl group optionally substituted with a group selected from the group consisting of OH and OCH3 is used. 1-3 C is alkyl, and in one embodiment, optionally substituted with OH. 1-3 alkyl, and in one embodiment, C optionally substituted with OCH 1-3 alkyl, and in one embodiment C 1-3 It is alkyl or halogen, and in one embodiment, it is methyl, ethyl, methoxymethyl or F, and in another embodiment, it is methyl, ethyl or F. Some embodiments of the acceptable substituents for the "optionally substituted 4- to 6-membered saturated heterocyclic group," "optionally substituted pyrrolidinyl," "optionally substituted piperidinyl," "optionally substituted oxetanyl," "optionally substituted tetrahydrofuranyl," and "optionally substituted tetrahydropyranyl" include C, which is optionally substituted with a group selected from the group consisting of F, OH, and OCH3. 1-3 In one embodiment, it is F, OH, or OCH3, in another embodiment, it is OH or methyl, and in another embodiment, it is C optionally substituted with a group selected from the group consisting of F, OH, and OCH3. 1-3 C is alkyl, F, oxo, or oxetanyl, and in one embodiment, may be substituted with a group selected from the group consisting of F, OH, and OCH 1-3 C is alkyl or oxo, and in one embodiment, may be substituted with a group selected from the group consisting of F, OH, and OCH3. 1-3 C is alkyl, and in one embodiment, optionally substituted with F. 1-3 C is alkyl, and in one embodiment, optionally substituted with OH. 1-3 alkyl, and in one embodiment, C optionally substituted with OCH 1-3 alkyl, and in some embodiments, C 1-3 It is alkyl. "Optionally substituted pyrrolidinediyl", "optionally substituted piperidinediyl", "optionally substituted piperazinediyl", "optionally substituted C 1-3 Some embodiments of the permissible substituents for "alkylene" include F, OH, OCH3, or optionally substituted C 1-3 In one embodiment, it is F, OH, OCH3, methyl, ethyl, hydroxymethyl, or methoxymethyl, and in another embodiment, it is F, OH, OCH3, or methyl. "C optionally substituted with F 1-3 In one embodiment, "alkyl" is methyl optionally substituted with F or ethyl optionally substituted with F. For example, methyl, ethyl, monofluoromethyl, difluoromethyl, trifluoromethyl, monofluoroethyl, difluoroethyl, and trifluoroethyl. In one embodiment, it is methyl, ethyl, monofluoromethyl, difluoromethyl, or difluoroethyl, in one embodiment, monofluoromethyl or difluoromethyl, in one embodiment, monofluoromethyl or difluoroethyl, in one embodiment, difluoromethyl or difluoroethyl, in one embodiment, monofluoromethyl, in one embodiment, difluoromethyl, in one embodiment, difluoroethyl, and in one embodiment, 2,2-difluoroethyl. "C optionally substituted with OH 1-3 In one embodiment, "alkyl" is methyl optionally substituted with one OH or ethyl optionally substituted with one or two OH. For example, methyl, ethyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, 1,2-dihydroxyethyl. In one embodiment, it is methyl, ethyl, or hydroxymethyl, in another embodiment, it is methyl or hydroxymethyl, in another embodiment, it is hydroxymethyl or hydroxyethyl, in another embodiment, it is hydroxymethyl, and in another embodiment, it is hydroxyethyl. "C optionally substituted with OCH3 1-3In one embodiment of "alkyl," it is methyl optionally substituted with one OCH3, ethyl optionally substituted with one to two OCH3, or propyl optionally substituted with one to three OCH3. For example, it is methyl, ethyl, methoxymethyl, 1-methoxyethyl, 2-methoxyethyl, 1,2-dimethoxyethyl, or 2-methoxypropyl. In one embodiment, it is methoxymethyl or methoxyethyl, in another embodiment, methoxymethyl, in another embodiment, methoxyethyl, or in another embodiment, 2-methoxypropyl. One embodiment of the "phenylene optionally substituted with F" is phenylene optionally substituted with 1 or 2 F. One embodiment is phenylene optionally substituted with one F, one embodiment is phenylene or fluorophenylene, one embodiment is phenylene, one embodiment is 2-fluoro-1,4-phenylene, and one embodiment is 3-fluoro-1,4-phenylene. "Halogeno C 1-6 "Alkyl" means a C alkyl group substituted with one or more halogens. 1-6 In one embodiment, C is substituted with one or more F. 1-6 alkyl, and in some embodiments, C substituted with 1 to 3 F. 1-6 In one embodiment, it is difluoromethyl, and in another embodiment, it is trifluoromethyl. "EUB" refers to a group capable of binding to an E3 ubiquitin ligase. In one embodiment, the group is capable of binding to an E3 ubiquitin ligase selected from the group consisting of VHL (von Hippel-Lindau), CRBN (cereblon), IAP (inhibitor of apoptosis protein), MDM2 (mouse double minute 2 homolog), DCAF11 (DDB1 and CUL4 associated factor 11), DCAF15 (DDB1 and CUL4 associated factor 15), DCAF16 (DDB1 and CUL4 associated factor 16), BIRC2 (baculoviral IAP repeat containing 2), KEAP1 (Kelch-like ECH-associated protein 1), RNF4 (RING finger protein 4), RNF114 (RING finger protein 114), FEM1B (protein fem-1 homolog B), and AhR (aryl hydrocarbon receptor). In one embodiment, the group is capable of binding to an E3 ubiquitin ligase selected from the group consisting of VHL, IAP, and MDM2. In one embodiment, the group is capable of binding to VHL or CRBN. In one embodiment, the group is capable of binding to VHL. In one embodiment, the group is capable of binding to CRBN. Those skilled in the art can understand this by referring to the following documents, but the present invention is not limited to these. [Literature] Current Research in Chemical Biology., 2022, 2, 100020 Front. Chem., 2021, 9, 707317 J. Am. Chem. Soc., 2021, 143, 5141 Signal Transduct. Target. Ther., 2020, 5, 129 Nat. Chem. Biol., 2019, 15(7), 737 Communications Biology., 2020, 3, 140 Sci. Rep., 2020, 10(1), 15543 ACS Chem. Biol., 2019, 14, 2430 Cell Chem. Biol., 2021, 28(4), 559 J. Am. Chem. Soc., 2022, 144, 701 ACS Chem. Biol., 2019, 14, 2822 The term "RAS protein" refers to RAS family proteins including KRAS, HRAS, and NRAS, and in one embodiment refers to KRAS, HRAS, and / or NRAS, and in another embodiment refers to KRAS. The RAS protein referred to here includes mutant RAS proteins, particularly mutant KRAS, such as G12V, G12D, and G12C mutant KRAS. "Mutated KRAS" refers to a KRAS having a mutation, such as a G12V mutant KRAS, a G12D mutant KRAS, and a G12C mutant KRAS. In one embodiment, the mutant KRAS is a G12V mutant KRAS, a G12D mutant KRAS, and / or a G12C mutant KRAS, in another embodiment, a G12V mutant KRAS, in another embodiment, a G12D mutant KRAS, and in another embodiment, a G12C mutant KRAS. "G12V mutation" refers to a mutation in which the amino acid residue corresponding to the 12th amino acid in the wild-type protein is converted from glycine to valine. "G12V mutated KRAS" refers to KRAS having the above-mentioned "G12V mutation." "G12D mutation" refers to a mutation in which the amino acid residue corresponding to the 12th amino acid in the wild-type protein is converted from glycine to aspartic acid. "G12D mutant KRAS" refers to KRAS having the above-mentioned "G12D mutation." "G12C mutation" refers to a mutation in which the amino acid residue corresponding to the 12th amino acid in the wild-type protein is converted from glycine to cysteine. "G12C mutant KRAS" refers to KRAS having the above-mentioned "G12C mutation." "Z Ｎ１ " is the following formula (Z N1 -1) to (Z N1 -15) ( ＊ＬＧＺ is LG Z or L P indicates the bond with R Z1’ are, independently of each other, optionally substituted C 1-6 Alkyl, halogen, cyano, -OH, -O-(optionally substituted C 1-6 alkyl), -S-(optionally substituted C 1-6 alkyl), -NH-(optionally substituted C 1-6 alkyl) or -N-(optionally substituted C 1-6 alkyl)2, n' is an integer from 0 to 2, and R Z2’ , R Z3’ and R Z４’ are each independently H or optionally substituted C 1-6 alkyl, and ring B1′ is a benzene ring or a 6-membered heterocycle, wherein R Z1’ and- ＊ＬＧZ forms a bond with the carbon atom constituting ring B1'. "Z Ｎ２ " is the following formula (Z N2 -1) to (Z N2 -15) ( ＊ＬＧＺ is LG Z or L P indicates the bond with R Z1’ are, independently of each other, optionally substituted C 1-6 Alkyl, halogen, cyano, -OH, -O-(optionally substituted C 1-6 alkyl), -S-(optionally substituted C 1-6 alkyl), -NH-(optionally substituted C 1-6 alkyl) or -N-(optionally substituted C 1-6 alkyl)2, n' is an integer from 0 to 2, and R Z2’ and R Z3’are each independently H or optionally substituted C 1-6 alkyl, and ring B1′ is a benzene ring or a 6-membered heterocycle, wherein R Z1’ and- ＊ＬＧZ forms a bond with the carbon atom constituting ring B1'. "Z Ｃ " is the following formula (Z C -16) to (Z C -27) ( ＊ＬＧＺ is LG Z or L P indicates the bond with R Z1’ are, independently of each other, optionally substituted C 1-6 Alkyl, halogen, cyano, -OH, -O-(optionally substituted C 1-6 alkyl), -S-(optionally substituted C 1-6 alkyl), -NH-(optionally substituted C 1-6 alkyl) or -N-(optionally substituted C 1-6 alkyl)2, n' is an integer from 0 to 2, and R Z2’ , R Z4’ and R Z５’ are each independently H or optionally substituted C 1-6 alkyl, and M' is a bond, -O-, -S-, -N(R M’ )- or optionally substituted C 1-３ alkylene, and R M’ is H or optionally substituted C 1-３ alkyl, ring B1′ is a benzene ring or a 6-membered heterocycle, and ring B2′ is a benzene ring or a 5- to 6-membered heterocycle, wherein R Z1’ and- ＊ＬＧZ forms a bond with the carbon atom constituting ring B1', and M', R Z1’ and- ＊ＬＧZ forms a bond with the carbon atom constituting ring B2'. The term "antigen" is used to refer to a molecule or a portion of a molecule to which an antigen-binding protein, such as an antibody or an antigen-binding fragment, can specifically bind. An antigen can be a protein, a nucleic acid, or other molecule. An antigen may have one or more epitopes that can interact with different antibodies, etc. Antibodies (or immunoglobulins) are glycoproteins with a basic structure consisting of a four-chain structure with a symmetric Y-shape, consisting of two heavy chains with a single sequence and two light chains with a single sequence. There are five classes of antibodies: IgG, IgM, IgA, IgD, and IgE. Heavy chains typically consist of polypeptide chains containing approximately 440 amino acids and have characteristic structures for each class. These are called Igγ, Igμ, Igα, Igδ, and Igε for IgG, IgM, IgA, IgD, and IgE, respectively. IgG subclasses include IgG1, IgG3, IgG4, and IgG4, with corresponding heavy chains called Igγ1, Igγ2, Igγ3, and Igγ4. Light chains typically consist of polypeptide chains containing approximately 220 amino acids. Two types, lambda and kappa, are known: Igλ and Igκ. The two types of light chains can pair with either type of heavy chain. Antibody molecules have four intrachain disulfide bonds in heavy chains (five in Igμ and Igε) and two in light chains, forming a loop every 100–110 amino acid residues. The three-dimensional structures of these disulfide bonds are similar between each loop and are called structural units or domains. The domain located at the N-terminus of both heavy and light chains is called the variable region. It has diverse amino acid sequences even among antibodies of the same class (or subclass) from the same animal species, and is known to be involved in the specificity of antibody-antigen binding. The amino acid sequence of the C-terminal domain downstream of the variable region is nearly constant for each class or subclass and is called the constant region. From the N-terminus to the C-terminus, the heavy chain contains a heavy chain variable region (VH) and a heavy chain constant region (CH). The CH is further divided into three domains from the N-terminus: CH1, CH2, and CH3. From the N-terminus to the C-terminus, the light chain contains a light chain variable region (VL) and a light chain constant region (CL). The amino acid sequences of the three complementarity-determining regions (CDRs) present in VH and VL vary greatly, contributing to the variability of the variable regions. CDRs are regions consisting of approximately 5 to 10 amino acid residues and are located at the N-terminus of the heavy and light chains, in the order CDR1, CDR2, and CDR3, respectively, and form the antigen-binding site. On the other hand, the parts of the variable regions other than the CDRs are called framework regions (FRs), which consist of FR1 to FR4 and show relatively little variation in amino acid sequence. When an antibody is treated with the protease papain, three antibody fragments are obtained: the two N-terminal fragments are called Fab (Fragment, antigen binding) regions, and the C-terminal fragment is called Fc (Fragment, crystallizable) region. As used herein, the term "antibody" refers to a polypeptide that specifically binds to an antigen and may have any structure as long as it is capable of specifically binding to the antigen. For example, antibodies include polypeptides with a four-chain structure as a basic structure, such as IgG, as well as various polypeptide forms, such as antigen-binding fragments and multispecific antibodies (e.g., bispecific antibodies), which will be described below. An "antigen-binding fragment" is a molecule containing at least one polypeptide chain that has antigen-binding activity derived from an antibody. Representative antigen-binding fragments include single-chain variable region fragments (scFv), Fab fragments, Fab' fragments, and F(ab')2 fragments. scFv is a monovalent antigen-binding fragment consisting of a VH and VL linked by a linker. Fab fragments are monovalent antigen-binding fragments consisting of a light chain and a fragment containing the VH and CH1 domains of the heavy chain. Fab' fragments are monovalent antigen-binding fragments consisting of a fragment containing the light chain, the VH and CH1 domains of the heavy chain, and part of the hinge region, and this hinge region contains cysteine residues that formed the inter-heavy chain disulfide bonds. F(ab')2 fragments are bivalent molecules in which Fab' fragments are linked by disulfide bonds. "Monovalent" means that they contain one antigen-binding site, and "bivalent" means that they contain two antigen-binding sites. The term "polypeptide" refers to a structure in which multiple amino acids are linked by peptide bonds. The amino acids used in a polypeptide may be either natural amino acids or artificial amino acids. The number of amino acid residues contained in a polypeptide may be two or more, and preferably ten or more. A "multispecific antibody" is an antibody that can specifically bind to two or more different antigens or to two or more different epitopes of the same antigen, and is called, for example, a bispecific antibody or a trispecific antibody depending on the number of antigens to which it binds. Multispecific antibodies include complexes of two or more antibodies and / or antigen-binding fragments, each capable of binding to a different antigen, and the term "antibody" as used herein includes multispecific antibodies unless otherwise limited by the context. A "human antibody" refers to an antibody having a human immunoglobulin amino acid sequence. As used herein, a "humanized antibody" refers to an antibody in which some, most, or all of the amino acid residues other than the CDRs have been substituted with amino acid residues derived from a human immunoglobulin molecule. The humanization method is not particularly limited, and humanized antibodies can be prepared by referring to, for example, U.S. Pat. No. 5,225,539 and U.S. Pat. No. 6,180,370. "Post-translational modification" refers to post-translational modification of an antibody when it is expressed in a cell. Examples of post-translational modifications include N-linked or O-linked glycosylation, N-terminal or C-terminal processing, deamidation, aspartic acid isomerization, and methionine oxidation. Such post-translational modifications are known to occur in various antibodies (J. Pharma. Sci., 2008; Vol. 97: pp. 2426-2447). The amino acid residue numbers of antibodies used herein can be specified according to the Kabat numbering system or the EU index (Kabat et al., Sequences of Proteins of Immunological Interest, 5th Ed., 1991, NIH Publication No. 91-3242) by designating them. "Identity" refers to the Identity value obtained using EMBOSS Needle (Necleic Acids Res., 2015; Vol. 43: pW580-W584) with the default parameters. The parameters are as follows: Gap Open Penalty = 10 Gap Extend Penalty = 0.5 Matrix = EBLOSUM62 End Gap Penalty = false In this specification, antibodies and antigen-binding fragments may be collectively referred to as "Ab." An "antibody-drug conjugate" is a conjugate in which an antibody and a drug are linked via a linker. The antibody can transport the drug to targeted cells or tissues. In one embodiment, the antibody-drug conjugate is a conjugate in which the antibody and the drug are linked via a linker that is cleavable in vivo. In another embodiment, the antibody-drug conjugate is a conjugate in which the antibody and the drug are linked via a non-cleavable linker. The "compound-to-antibody ratio" refers to the average number of compounds bound to one antibody in an antibody-drug conjugate. The compound-to-antibody ratio can be measured and calculated by known means such as hydrophobic interaction HPLC or LC-MS. A "linker" is a divalent chemical group that connects one functional compound to another. A "linker cleavable in vivo" is a linker having a partial structure that is cleavable in vivo. A "partial structure cleavable in vivo" is a partial structure that can be cleaved in vivo by the action of an enzyme or the like. Examples of enzymes that cleave the partial structure cleavable in vivo include proteases, glycosidases, esterases, and phosphatases. Examples of proteases include cathepsin B, cathepsin S, plasmin, and legumain. Examples of glycosidases include β-glucuronidase and β-galactosidase. Examples of esterases include carboxyesterase, but are not limited to these. The term "non-cleavable linker" refers to a linker that is not degraded in vivo, particularly in lysosomes, under acidic conditions, or by the action of glycosidases or proteases. For example, C=O, C 1-6 Alkylene, C(=O)NH-C 1-6 alkylene, or polyethylene glycol. "Subject" means a human or other animal in need of such prevention or treatment. In one embodiment, the subject is a human in need of such treatment or prevention. The antibody-drug conjugate or salt thereof of the present invention, and the drug (D) and linker (L) constituting the antibody-drug conjugate or salt thereof A The embodiments of the antibody (Ab) and the antibody (Ab) are shown below. Even if a combination is not specifically described, one or more embodiments can be combined with other embodiments. In other words, all embodiments can be freely combined. 1. Drugs (D) The drug (D) constituting the antibody-drug conjugate or a salt thereof of the present invention is a heterocyclic compound having an activity of inducing RAS proteolysis, particularly an activity of inducing mutant KRAS proteolysis, particularly an activity of inducing G12V, G12D, and G12C mutant KRAS proteolysis. The linker (L A The drug (D) exerts its effect when part or all of the drug (D) is cleaved in tumor cells, liberating the drug (D). Some embodiments of the drug (D) of the present invention are shown below. (1-1) A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein. (1-2) A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II): (1-3) A heterocyclic compound or a salt thereof having an RAS protein degradation-inducing activity. (2-1) A is CR A , or N and R A is H or C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (2-2) A is CR A , or N and R A A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), wherein (2-3) A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof, wherein A is N. (2-4) A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof, wherein A is CH. (3-1) X 1 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein - is -CH2- or -O-. (3-2) X 1 A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), wherein -O- is -O-. (4-1) R 1 is cyano, OH, halogen, and optionally substituted C 1-3 naphthyl optionally substituted with one or two groups selected from the group consisting of alkyl, or a group selected from the group consisting of the following formula (III), formula (III-b) and formula (III-c): R 1a , R 1b and R 1c are each independently H, vinyl, halogen, or optionally substituted C 1-3A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (4-2) R 1 represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R 1a is H, methyl, F or Cl, R 1b A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein R is F, Cl, methyl or ethyl. (4-3) R 1 is a group represented by formula (III), R 1a is H, methyl, F or Cl, R 1b A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein R is F, Cl, methyl or ethyl. (4-4) R 1 is a group represented by formula (III), R 1a is H, methyl, F or Cl, R 1b A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein R is methyl. (4-5) R 1 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), which is a group represented by the following formula (III-a): (5-1) R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (5-2) R 2 is optionally substituted with halogen, cyclopropyl, vinyl, or a group selected from the group consisting of OH and OCH1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (5-3) R 2 is a halogen, C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is alkyl, cyclopropyl, or vinyl. (5-4) R 2 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein R is cyclopropyl. (6-1) R 3 is a heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), which is a group selected from the group consisting of formula (IV), formula (V), formula (VI), formula (VII), formula (VIII), formula (IX), formula (X), formula (XI), formula (XII) and formula (XIII), or a salt thereof. (6-2) R 3 is a heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), which is a group selected from the group consisting of formula (IV), formula (V), formula (VI), formula (VII), formula (VIII), formula (IX), formula (X), formula (XI), and formula (XII), or a salt thereof. (6-3) R 3 is a heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is a group selected from the group consisting of formulas (IV), (V), (VI), (IX-a), and (XI): (6-4) R 3 is a heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, which is a group selected from the group consisting of formula (IV-a), formula (Va), formula (VI-a), formula (IX-a), and formula (XI): (6-5) R 3is a heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), which is a group selected from the group consisting of formula (IV-a), formula (Va), and formula (VI-a): (6-6) R 3 is a heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), which is a group selected from the group consisting of formula (IV-a), formula (Va), and formula (XI): (6-7) R 3 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation inducing activity represented by formula (II), which is a group selected from the group consisting of formula (IV-a) and formula (Va): (6-8) R 3 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), which is a group selected from the group consisting of formula (IV-a) and formula (XI): (6-9) R 3 A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), which is a group represented by the following formula (XI): (6-10) R 3 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation inducing activity represented by formula (II), which is a group selected from the group consisting of formulas (IV), (V), and (XI): (6-11) R 3 A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), which is a group represented by the following formula (IV-a): (7-1) R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), wherein the heterocyclic compound is a cycloalkyl. (7-2) R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Pyrrolidinyl optionally substituted with alkyl; C 1-3 piperidinyl optionally substituted with alkyl; or C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), wherein the heterocyclic compound is a cycloalkyl. (7-3) R 3a is -(CH2) p CHR 3f -NR N1 RN2 , or -(CH2) p CHR 3f -OR 3g A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II): (7-4) R 3a is -(CH2) p CHR 3f -NR N1 R N2 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II): (8-1) R 3b is H or C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (8-2) R 3b A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein R is H or methyl. (8-3) R 3b A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), wherein (9-1) R 3c and R 3d is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 cycloalkyl, provided that R 3c -(CH2) p CHR 3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation inducing activity, represented by formula (II): (9-2) R 3c is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Pyrrolidinyl optionally substituted with alkyl; C 1-3 piperidinyl optionally substituted with alkyl; or C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 cycloalkyl, provided that R 3c -(CH2) p CHR 3f -NR N1 R N2 In this case, X in formula (Va) 2 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein is -O- or -NH-. (9-3) R 3c is -(CH2) p CHR 3f -NR N1 R N2 ;C1-3 pyrrolidinyl optionally substituted with alkyl; or -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, and X of formula (Va) 2 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein is -O- or -NH-. (9-4) R 3c is -NR N1 R N2 C optionally substituted with 3-6 A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), wherein the heterocyclic compound is a cycloalkyl. (9-5) R 3d is -(CH2) p CHR 3f -NR N1 R N2 Or, C 1-3 Alkyl, C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a heterocyclic compound having an activity of inducing degradation of mutant KRAS proteins, represented by formula (II), or a salt thereof, wherein the heterocyclic compound is a 4- to 6-membered saturated heterocyclic group containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, and optionally substituted with a group selected from the group consisting of: (10-1) R 3e -OC 2-3 Alkylene-NR N1 R N2 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II): (11-1) R 3f is H, F or C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (11-2) R 3f is H or C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (11-3) R 3f A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), wherein (12-1) R 3g is H or C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (12-2) R 3g A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), wherein (13-1) R 3h is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms, or a salt thereof, having the activity of inducing mutant KRAS protein degradation. (13-2) R 3h A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein: is an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms. (14-1) R 3i are the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２ , a group selected from the group consisting of halogen, -CN, and oxo; or Two R's on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3alkyl), OH, halogen, and oxo; or R on two adjacent carbon atoms 3i together with the two carbon atoms to form C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two non-adjacent carbon atoms 3i may form a bridged structure consisting of 1 to 2 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C 1-3 Alkyl, -O-(C 1-3 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II), which may be substituted with 1 to 2 groups selected from the group consisting of alkyl, OH, halogen, and oxo. (15-1) R N1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2 may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 and R may, together with the carbon atom and nitrogen atom to which they are bonded, form an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, or a salt thereof, having the activity of inducing degradation of mutant KRAS proteins. (15-2) R N1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2 and (b) may, together with the nitrogen atom to which they are bonded, form an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, or a salt thereof, having the activity of inducing mutant KRAS protein degradation. (15-3) R N1 and R N2 are the same or different and are H or C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (15-4) R N1 and R N2 are the same or different and both are C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (15-5) R N1 is C 1-3 alkyl, and R N2 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein (16-1) X 2 is -O-, -NH-, or -N(C 1-3 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II): (16-2) X 2 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation inducing activity represented by formula (II), wherein -O-, -NH-, or -N(CH3)-. (16-3) X 2 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II): (16-4) X 2A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein -NH- is -NH-. (16-5) X 2 A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), wherein -O- is -O-. (17-1) X 3 is O or S, a heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof. (17-2) X 3 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein (18-1) X 4 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation inducing activity represented by formula (II), wherein -CH2-, -CH2-CH2-, or -O-CH2-. (19-1) A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein n is 1 or 2. (19-2) A heterocyclic compound or a salt thereof having an activity of inducing mutant KRAS protein degradation, represented by formula (II), wherein n is 1. (19-3) A heterocyclic compound or a salt thereof having a mutant KRAS protein degradation-inducing activity represented by formula (II), wherein n is 2. (20-1) A heterocyclic compound or a salt thereof having an activity of inducing mutant KRAS protein degradation, represented by formula (II), wherein p is 1 or 2. (20-2) A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein p is 1. (20-3) A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II), wherein p is 2. (21-1) A heterocyclic compound or a salt thereof having an activity of inducing mutant KRAS protein degradation, represented by formula (II), wherein q is an integer of 1 to 8. (22-1) R 4 are F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a)2, R 4a pyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4a C optionally substituted with F 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (22-2) R 4 are F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4a C optionally substituted with a group selected from the group consisting of pyrrolidinyl optionally substituted with 1-6 Alkyl; R 4b piperidinyl optionally substituted by R 4a is C 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (22-3) R 4 is OCH 3、 R 4a , N(R 4a )2, R 4a C optionally substituted with a group selected from the group consisting of pyrrolidinyl optionally substituted with 1-6 Alkyl; R 4b piperidinyl optionally substituted by R 4ais C 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (22-4) R 4 is OCH 3、 and tetrahydrofuranyl, 1-6 a heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof, wherein the heterocyclic compound is alkyl; or tetrahydropyranyl; (22-5) R 4 may be substituted with OCH3 1-6 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II), wherein the heterocyclic compound is alkyl or tetrahydropyranyl. (22-6) R 4 C may be substituted with OCH3 1-6 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (22-7) R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (22-8) R 4 is N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl, and R 4a is C 1-3A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (22-9) R 4 is N(R 4a )2 is substituted with C 1-6 alkyl, and R 4a is C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (23-1) EUB is a group capable of binding to E3 ubiquitin ligase, and is a heterocyclic compound having an activity of inducing degradation of mutant KRAS protein represented by formula (II) or a salt thereof. (23-2) EUB is a group capable of binding to VHL, and is a heterocyclic compound having an activity of inducing mutant KRAS protein degradation represented by formula (II) or a salt thereof. (23-3) A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof, wherein EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV). (In the formula, R 5 is methyl, ethyl, isopropyl, isobutyl, sec-butyl, tert-butyl, C 3-6 cycloalkylmethyl, or C 3-6 is cycloalkyl, R 6a and R 6b are the same or different and may be substituted with H or a group selected from the group consisting of OH, OCH3, and N(CH3)2; 1-6 alkyl, or R 6a , R 6b may be substituted together with the carbon to which they are attached. 3-6 It may form a cycloalkane or an optionally substituted 4- to 6-membered saturated heterocycle containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen as ring-constituting atoms, R 7is an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or a 6-membered heteroaryl containing 1 to 3 nitrogen atoms, W is an optionally substituted phenylene or an optionally substituted 6-membered heteroarenediyl containing 1 to 3 nitrogen atoms as ring-constituting atoms; Z is NH or a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring atoms. (23-4) EUB is a group capable of binding to CRBN, and is a heterocyclic compound having an activity of inducing mutant KRAS protein degradation represented by formula (II) or a salt thereof. (23-5) EUB is a group capable of binding to VHL or CRBN, and is a heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof. (23-6) EUB is a group capable of binding to CRBN, and the group capable of binding to CRBN is a group represented by the following formula (E-1): G is CR G or N, R G But H or C 1-６ is alkyl, Z Ar However, the following formulas (Z-1), (Z-2), (Z-3), (Z-4), (Z-5), (Z-6), (Z-7), (Z-8), (Z-9), (Z-10), (Z-11), (Z-12), (Z-13), (Z-14), (Z-15), ( 1 group selected from the group consisting of Z-16), (Z-17), (Z-18), (Z-19), (Z-20), (Z-21), (Z-22), (Z-23), (Z-24), (Z-25), (Z-26) and (Z-27), Here, the formulas (Z-1), (Z-2), (Z-3), (Z-4), (Z-5), (Z-6), (Z-7), (Z-8), (Z-9), (Z-10), (Z-11), (Z-12), (Z-13), (Z-14), (Z-15), (Z-16), (Z -17), (Z-18), (Z-19), (Z-20), (Z-21), (Z-22), (Z-23), (Z-24), (Z-25), (Z-26) and (Z-27), ring B1 and ring B2 are L P It forms a bond with However, if G is N, then Z Ar is a group selected from the group consisting of formulas (Z-1), (Z-16), (Z-17), (Z-18), (Z-19), (Z-20), (Z-21), (Z-22), (Z-23), (Z-24), (Z-25), (Z-26) and (Z-27), R Z1 are, independently of each other, optionally substituted C 1-6 Alkyl, halogen, cyano, -OH, -O-(optionally substituted C 1-6 alkyl), -S-(optionally substituted C 1-6 alkyl), -NH-(optionally substituted C 1-6 alkyl) or -N-(optionally substituted C 1-6 alkyl)2, p' is an integer from 0 to 2, R Z2 , R Z3 , R Z4 and R Z5 are each independently H or optionally substituted C 1-6 is alkyl, M is a bond, -O-, -S-, -N(R M )- or optionally substituted C 1-３ is alkylene, R M is H or optionally substituted C 1-３ is alkyl, Ring B1 is a benzene ring or a 6-membered heterocycle, where R Z1 and LP forms a bond with the carbon atom constituting ring B1, Ring B2 is a benzene ring or a 5- or 6-membered heterocycle, Here, M, R Z1 and L P a heterocyclic compound or a salt thereof having an activity of inducing degradation of mutant KRAS protein, represented by formula (II), in which R forms a bond with a carbon atom constituting ring B2. (23-7) EUB is a group capable of binding to CRBN, and the group capable of binding to CRBN is a group represented by the following formula (E-1): G is CH or N; Z Ar is a group selected from the group consisting of the following formulae (Z-1A), (Z-1B), (Z-5A), (Z-5B), (Z-14A), (Z-14B), (Z-14C), (Z-15A), (Z-16A), (Z-16B), (Z-16C), (Z-16D), (Z-20A), (Z-22A), (Z-23A), (Z-23B), (Z-23C), (Z-23D), (Z-23E), (Z-23F) and (Z-24A), Here, the benzene ring or 6-membered heterocycle in the formulae (Z-1A), (Z-1B), (Z-5A), (Z-5B), (Z-14A), (Z-14B), (Z-14C), (Z-15A), (Z-16A), (Z-16B), (Z-16C), (Z-16D), (Z-20A), (Z-22A), (Z-23A), (Z-23B), (Z-23C), (Z-23D), (Z-23E) and (Z-23F) is L P The benzene ring in (Z-24A) is L P It forms a bond with However, if G is N, then Z Ar is a group selected from the group consisting of (Z-1A), (Z-16A), (Z-16B), (Z-16C), (Z-16D), (Z-20A), (Z-22A), (Z-23A), (Z-23B), (Z-23C), (Z-23D), (Z-23E), (Z-23F) and (Z-24A), a heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof. (23-8) EUB is a group capable of binding to CRBN, and the group capable of binding to CRBN is a group represented by the following formula (E-1): G is CH or N; Z Ar is a group selected from the group consisting of the following formula (Z-1A) or (Z-16A), Here, the benzene ring in the formulas (Z-1A) and (Z-16A) is L P A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II): (23-9) EUB is a heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof, which is a group capable of binding to one E3 ubiquitin ligase selected from the group consisting of VHL, CRBN, IAP, MDM2, DCAF11, DCAF15, DCAF16, BIRC2, KEAP1, RNF4, RNF114, FEM1B, and AhR. (24-1) R 5 However, methyl, ethyl, isopropyl, isobutyl, sec-butyl, tert-butyl, C 3-6 cycloalkylmethyl, or C 3-6 A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), wherein the heterocyclic compound is a cycloalkyl. (24-2) R 5 is ethyl, isopropyl, isobutyl, sec-butyl, tert-butyl, or C 3-6 A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), wherein the heterocyclic compound is a cycloalkyl. (24-3) R 5 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II): (24-4) R 5 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II): (24-5) R5 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein R is isopropyl. (25-1) R 6a and R 6b are the same or different and may be substituted with H or a group selected from the group consisting of OH, OCH3, and N(CH3)2; 1-6 alkyl, or R 6a , R 6b may be substituted together with the carbon to which they are attached. 3-6 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II), which may form a cycloalkane or an optionally substituted 4- to 6-membered saturated heterocycle containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. (25-2) R 6a and R 6b are the same or different and may be substituted with H or a group selected from the group consisting of OH, OCH3, and N(CH3)2; 1-6 alkyl, or R 6a , R 6b may be substituted together with the carbon to which they are attached. 3-6 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity, represented by formula (II), which may form a cycloalkane or an optionally substituted 4- to 6-membered saturated heterocycle containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. (25-3) R 6a and R 6b are the same or different and may be substituted with H or a group selected from the group consisting of OH, OCH3, and N(CH3)2; 1-6 alkyl, or R 6a , R 6b may be substituted together with the carbon to which they are attached. 3-6A heterocyclic compound or a salt thereof which may form a cycloalkane and has an activity of inducing the degradation of mutant KRAS protein and is represented by formula (II): (25-4) R 6a and R 6b are different from each other and may be substituted by H or OH; 1-6 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (25-5) R 6a is H and R 6b C may be substituted with OH 1-6 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (25-6) R 6a is H and R 6b A heterocyclic compound or a salt thereof having mutant KRAS protein degradation inducing activity, represented by formula (II): (26-1) R 7 is an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or a 6-membered heteroaryl containing 1 to 3 nitrogen atoms, as ring-constituting atoms, or a heterocyclic compound or salt thereof having mutant KRAS protein degradation-inducing activity. (26-2) R 7 is a group selected from the group consisting of the following formulas (XIX), (XX), (XXI), (XXII), (XXIII), (XXIV), (XXV), (XXVI), (XXVII), (XXVIII), and (XXIX), R 7a , R 7b are the same or different and may be substituted by H or OH; 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (26-3) R 7is a group selected from the group consisting of the following formulas (XIX), (XX), (XXII), (XXIV), and (XXIX), R 7a , R 7b are the same or different and may be substituted by H or OH; 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (26-4) R 7 is a group selected from the group consisting of formula (XIX), formula (XX), formula (XXII), formula (XXIV), and formula (XXIX), R 7a , R 7b are the same or different and are H or C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (26-5) R 7 is a group selected from the group consisting of the following formulas (XIX), (XX), and (XXIV), R 7a , R 7b are the same or different and are H or C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (26-6) R 7 is a heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), which is a group selected from the group consisting of formula (XIX-a), formula (XX-a), and formula (XVI) below. (26-7) R 7 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), which is a group represented by the following formula (XIX-a): (26-8) R 7 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), which is a group represented by the following formula (XVI): (26-9) R 7 A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II), which is a group represented by the following formula (XX-a): (26-10) R 7 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation inducing activity represented by formula (II), which is a group selected from the group consisting of formula (XIX-a) and formula (XVI) below. (26-11) R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or a salt thereof, having the activity of inducing mutant KRAS protein degradation. (27-1) A heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by formula (II), wherein W is an optionally substituted phenylene or an optionally substituted 6-membered heteroarenediyl containing 1 to 3 nitrogen atoms as ring-constituting atoms, or a salt thereof. (27-2) W is a group represented by the following formula (XVII): W 1 is CH, CF, CCl, or CCH3, W 2 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein R is CH, CF, CCl, CCH3, or N. (27-3) W is a group represented by formula (XVII), and W 1 is CH and W 2 A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein R is CH or N. (27-4) A heterocyclic compound or a salt thereof having a mutant KRAS protein degradation-inducing activity represented by formula (II), wherein W is phenylene. (27-5) A heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof, wherein W is a group represented by formula (XVII-a). (28-1) A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof, wherein Y is phenylene optionally substituted with F or Cl, or pyridinediyl. (28-2) A heterocyclic compound having an activity of inducing mutant KRAS protein degradation, represented by formula (II), or a salt thereof, wherein Y is phenylene optionally substituted with F or Cl. (28-3) A heterocyclic compound having an activity of inducing mutant KRAS protein degradation, represented by formula (II), or a salt thereof, wherein Y is phenylene. (29-1) L P is a group that chemically bonds Y and EUB, and is a heterocyclic compound having an activity of inducing degradation of mutant KRAS protein, represented by formula (II), or a salt thereof. (29-2) L P is -(L 1 -L 2 -L 3 -L 4 )- and L 1 , L 2 , L 3 , L 4 are the same or different and represent a bond, -O-, -NR L1 -, optionally substituted pyrrolidinediyl, optionally substituted piperidinediyl, optionally substituted piperazinediyl, optionally substituted C 1-3 a group selected from the group consisting of alkylene and C═O; R L1 is H or C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (29-3) L P is a bond, C 1-3 alkylene, C═O, or a group selected from the group consisting of the following formulae (XXXI), (XXXII), (XXXIII), (XXXIV), (XXXV), and (XXXVI): R L1 is H or C 1-3 is alkyl, RL2 and R L3 are the same or different and are H, F, OH, OCH3 or optionally substituted C 1-3 is alkyl, R L is CH or N, A heterocyclic compound or a salt thereof having mutant KRAS protein degradation inducing activity represented by formula (II), wherein m2 is 1 or 2. (29-4) L P is a bond, C═O, or a group selected from the group consisting of the following formulae (XXXI) and (XXXII): R L1 is H or C 1-3 is alkyl, R L2 and R L3 are the same or different and are H, F, OH, OCH3 or optionally substituted C 1-3 is alkyl, A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein m2 is 1 or 2. (29-5) L P is a bond, C═O or a group selected from the group consisting of formula (XXXI) and formula (XXXII), R L1 is C 1-3 is alkyl, R L2 and R L3 are both H, A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein m2 is 1. (29-6) L P A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein R is a bond or C=O. (29-7) L P A heterocyclic compound or a salt thereof having mutant KRAS protein degradation-inducing activity represented by formula (II), wherein (29-8) L PA heterocyclic compound or a salt thereof having an activity of inducing mutant KRAS protein degradation, represented by formula (II): (29-9) L P is -(L 5 -L 6 -L 7 -L 8 )- and L 5 , L 6 , L 7 and L 8 are, independently of each other, a bond, C=O, -O-, -S-, -SO2-, -NR L -, acetylene-1,2-diyl, optionally substituted heterocycloalkylene, optionally substituted heteroarylene, saturated 7- to 9-membered spiroheterocycloalkylene containing 1 to 2 nitrogen atoms, saturated 7- to 9-membered bridged heterocycloalkylene containing 2 nitrogen atoms, and optionally substituted C 1-６ is a group selected from the group consisting of alkylene; R L is H or C 1-６ A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (29-10) L P is -(L 5 -L 6 -L 7 -L 8 )- and L 5 is C=O, L 6 is C 1-3 Piperidinediyl optionally substituted with alkyl, C 1-3 Piperazinediyl optionally substituted with alkyl, C 1-3 pyrrolidinediyl, bridged piperazinediyl or 2,6-diazaspiro[3.4]octanediyl, which may be substituted by alkyl; L 7 is a bond, -N(R L7 )-, C 1-3 alkylene or piperazinediyl, L 8 is a bond, -N(R L8)-, -O-, piperazinediyl or C 1-3 is alkylene, R L7 is H or C 1-3 is alkyl, R L8 is H or C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (29-11) L P is a group selected from the group consisting of the following formulae (L-1), (L-2), (L-3), (L-4), (L-5), (L-6) and (L-7), Here, C═O in the formulas (L-1), (L-2), (L-3), (L-4), (L-5), (L-6), and (L-7) forms a bond with Y, L' is -O-, -(C 1-3 alkylene)-NH-, -N(CH3)(C 1-3 alkylene)-, piperazinediyl or -(C 1-3 alkylene)-piperazinediyl, L'' is a bond, C 1-3 Alkylene, or -(C 1-3 alkylene)-O-; R L6 But H or C 1-3 A heterocyclic compound having mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein the heterocyclic compound is an alkyl. (29-12) L P is a group selected from the group consisting of the following formulae (L-1), (L-2), (L-3), (L-4), (L-5) and (L-7), Here, C═O in the formulas (L-1), (L-2), (L-3), (L-4), (L-5), and (L-7) forms a bond with Y, L' is -O-, -(C 1-3 alkylene)-NH-, -N(CH3)(C 1-3 alkylene)-, piperazinediyl or -(C 1-3 alkylene)-piperazinediyl, L'' is a bond, C1-3 Alkylene, or -(C 1-3 alkylene)-O-; R L6 But H or C 1-3 A heterocyclic compound represented by formula (II) or a salt thereof, wherein R is an alkyl group. (29-13) L P is the following formula (L-5A) or (L-7A), wherein C=O in formulas (L-5A) and (L-7A) forms a bond with Y, or a salt thereof. (29-14) L P is formula (L-5A), wherein C=O in formula (L-5A) forms a bond with Y, or a salt thereof. (30-1) A heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by formula (II), wherein Z is NH or a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, or a salt thereof. (30-2) A heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein Z is NH or a group selected from the group consisting of the following formulas (XXXVII), (XVIII), (XXXIX), and (XXXX): (30-3) A heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by formula (II), or a salt thereof, wherein Z is NH or a group selected from the group consisting of the following formulae (XXXVII-a), (XVIII-a), (XXXIX-a) and (XXXX-a): (In the formula, * is L P (Indicates the connection with (30-4) A heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof, wherein Z is a group selected from the group consisting of formula (XXXVII), formula (XVIII), formula (XXXIX), and formula (XXXX). (30-5) A heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof, wherein Z is a group selected from the group consisting of formula (XXXVII-a), formula (XVIII-a), formula (XXXIX-a), and formula (XXXX-a). (30-6) A heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof, wherein Z is a group represented by the following formula (XVIII): (30-7) A heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by formula (II) or a salt thereof, wherein Z is a group represented by the following formula (XVIII-a): (In the formula, * is L P (Indicates the connection with (30-8) A heterocyclic compound or a salt thereof having an activity of inducing mutant KRAS protein degradation, represented by formula (II), wherein Z is NH. (30-9) A heterocyclic compound having an activity of inducing mutant KRAS protein degradation, represented by formula (II), or a salt thereof, wherein Z is a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. (31) A heterocyclic compound or a salt thereof having the activity of inducing the degradation of mutant KRAS protein, represented by formula (II), which is a combination of two or more of the embodiments described in (1-1) to (30-9) above that do not contradict each other. Examples include, but are not limited to, the following heterocyclic compounds or salts thereof having the activity of inducing the degradation of mutant KRAS protein: (31-1) A heterocyclic compound having an activity of inducing the degradation of mutant KRAS protein represented by formula (II) or a salt thereof (In the formula, A is CR A , or N, R A is H or C 1-3 is alkyl, X 1 is —CH— or —O—, R 1represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R 1a is H, methyl, F or Cl, R 1b is F, Cl, methyl or ethyl, R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 is alkyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII), R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, R 3b is H or C 1-3 is alkyl, R 3c and R 3d is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, However, R 3c -(CH2) p CHR 3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 alkyl)-, R 3e -OC 2-3 Alkylene-NR N1 R N2 and R 3f is H, F or C 1-3 is alkyl, R 3g is H or C 1-3 is alkyl, R 3his an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms; R 3i are the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２ , a group selected from the group consisting of halogen, -CN, and oxo; or Two R's on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two adjacent carbon atoms 3i together with the two carbon atoms to form C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two non-adjacent carbon atoms 3i may form a bridged structure consisting of 1 to 1 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C1-3 Alkyl, -O-(C 1-3 optionally substituted with 1 to 2 groups selected from the group consisting of alkyl), OH, halogen, and oxo; R N1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2 may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 may form, together with the carbon atom and nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen, X 2 is -O-, -NH-, or -N(C 1-3 alkyl)-, X 3 is O or S, X 4 is -CH2-, -CH2-CH2-, or -O-CH2-, n is 1 or 2, p is 1 or 2; q is an integer from 1 to 8; R 4 F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4a pyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4aC optionally substituted with F 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3 is alkyl, Y is phenylene optionally substituted with F or Cl, or pyridinediyl; L P is a group that chemically bonds Y and EUB, EUB is a group capable of binding to E3 ubiquitin ligases). (31-2) A is CR A , or N, R A is H, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), and (XI): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, R 3f is H, R N1 and R N2 are the same or different and are H or C 1-3 It is an alkyl X 2 is —O— or —NH—, X 3 is O, n is 1, p is 1, R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 is alkyl, The antibody-drug conjugate or a salt thereof according to (31-2), wherein Y is phenylene. (31-3) A is N, R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3 The antibody-drug conjugate or a salt thereof according to (31-2), wherein the aryl group is alkyl. (31-4) The antibody-drug conjugate or a salt thereof according to (31-1), wherein EUB is a group capable of binding to VHL. (31-5) EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is methyl, ethyl, isopropyl, isobutyl, sec-butyl, tert-butyl, C 3-6 cycloalkylmethyl, or C 3-6 is cycloalkyl, R 6a and R 6b are the same or different and may be substituted with H or a group selected from the group consisting of OH, OCH3, and N(CH3)2; 1-6 alkyl, or R 6a , R 6b may be substituted together with the carbon to which they are attached. 3-6It may form a cycloalkane or an optionally substituted 4- to 6-membered saturated heterocycle containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen as ring-constituting atoms, R 7 is an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or a 6-membered heteroaryl containing 1 to 3 nitrogen atoms, W is an optionally substituted phenylene or an optionally substituted 6-membered heteroarenediyl containing 1 to 3 nitrogen atoms as ring-constituting atoms; L P is -(L 1 -L 2 -L 3 -L 4 )- and L 1 , L 2 , L 3 , L 4 are the same or different and represent a bond, -O-, -NR L1 -, optionally substituted pyrrolidinediyl, optionally substituted piperidinediyl, optionally substituted piperazinediyl, optionally substituted C 1-3 a group selected from the group consisting of alkylene and C═O; R L1 is H or C 1-3 is alkyl, The antibody-drug conjugate or a salt thereof according to (31-4), wherein Z is NH or a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. (31-6) EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6bare different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen; W is phenylene; L P is a bond, The antibody-drug conjugate or a salt thereof according to (31-5), wherein Z is a 5-membered heteroarenediyl containing, as ring-constituting atoms, 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen. (31-7) R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): The antibody-drug conjugate or salt thereof according to (31-6), wherein Z is a group represented by the following formula (XVIII): (31-8) A is CR A , or N, R A is H, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), and (XI): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6is cycloalkyl, R 3f is H, R N1 and R N2 are the same or different and are H or C 1-3 It is an alkyl X 2 is —O— or —NH—, X 3 is O, n is 1, p is 1, R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 is alkyl, Y is phenylene; EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV), R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen; W is phenylene; L P is a bond, A heterocyclic compound or a salt thereof having a mutant KRAS protein degradation-inducing activity, represented by formula (II) according to (31-1), wherein Z is a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. (31-9) A is N, R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3 is alkyl, R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): A heterocyclic compound or a salt thereof having a mutant KRAS protein degradation-inducing activity represented by formula (II) described in (31-8), wherein Z is a group represented by formula (XVIII) below. (31-10) A is CR A , or N, R A is H, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group selected from the group consisting of the following formula (IV-a) and formula (Va): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, R 3f is H, R N1 and RN2 are the same or different and are H or C 1-3 is alkyl, X 2 is —O— or —NH—, X 3 is O, p is 1, n is 1, R 4 C may be substituted with OCH3 1-6 is alkyl, Y is phenylene; L P is a bond, EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV), R 5 is isopropyl, R 6a is H and R 6b is hydroxymethyl, R 7 is a group selected from the group consisting of the following formula (XIX-a) and formula (XVI), W is a group represented by formula (XVII-a), Z is a group represented by the following formula (XVIII-a): A heterocyclic compound having an activity of inducing the degradation of mutant KRAS protein, represented by formula (II) according to (31-1), or a salt thereof. (In the formula, * L P ) indicates the connection point with . Specific embodiments of heterocyclic compounds having the activity of inducing the degradation of mutant KRAS proteins, which are used as drugs constituting the antibody-drug conjugate or salts thereof of the present invention, include heterocyclic compounds having the activity of inducing the degradation of mutant KRAS proteins selected from the group consisting of: (4R)-1-[(2S)-2-{4-[4-({[(7M)-4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-2-[3-(dimethylamino)-2,2-dimethylpropoxy]-7-(6-fluoro-5-methyl-1H-indazol-4-yl)quinazolin-8-yl]oxy}methyl)phenyl]-1H-1,2,3-triazol-1-yl}-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, (4R)-1-[(2S)-2-(4-{4-[({(7M)-4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-[(oxan-4-yl)oxy]quinazolin-8-yl}oxy)methyl]phenyl}-1H-1,2,3-triazol-1-yl)-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, (4R)-1-[(2S)-2-{4-[4-({[(7M)-4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-{[(3R)-1-methylpyrrolidin-3-yl]methoxy}quinazolin-8-yl]oxy}methyl)phenyl]-1H-1,2,3-triazol-1-yl}-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, and (4R)-1-[(2S)-2-(4-{4-[({(7M)-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-[(2S)-2-methoxypropoxy]-4-[(1-{[2-(methylamino)ethyl]carbamoyl}azetidin-3-yl)oxy]quinolin-8-yl}oxy)methyl]phenyl}-1H-1,2,3-triazol-1-yl)-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide. Furthermore, other embodiments of specific heterocyclic compounds having the activity of inducing the degradation of mutant KRAS proteins, which are used as drugs constituting the antibody-drug conjugate or salts thereof of the present invention, include heterocyclic compounds having the activity of inducing the degradation of mutant KRAS proteins selected from the following group, or salts thereof: (4R)-1-[(2S)-2-{4-[4-({[4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-2-[3-(dimethylamino)-2,2-dimethylpropoxy]-7-(6-fluoro-5-methyl-1H-indazol-4-yl)quinazolin-8-yl]oxy}methyl)phenyl]-1H-1,2,3-triazol-1-yl}-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, (4R)-1-[(2S)-2-(4-{4-[({4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-[(oxan-4-yl)oxy]quinazolin-8-yl}oxy)methyl]phenyl}-1H-1,2,3-triazol-1-yl)-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, (4R)-1-{(2S)-2-[4-(4-{[(4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-{[(3R)-1-methylpyrrolidin-3-yl]methoxy}quinazolin-8-yl)oxy]methyl}phenyl)-1H-1,2,3-triazol-1-yl]-3-methylbutanoyl}-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, and (4R)-1-[(2S)-2-(4-{4-[({6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-[(2S)-2-methoxypropoxy]-4-[(1-{[2-(methylamino)ethyl]carbamoyl}azetidin-3-yl)oxy]quinolin-8-yl}oxy)methyl]phenyl}-1H-1,2,3-triazol-1-yl)-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide. Further, other examples of heterocyclic compounds having the activity of inducing the degradation of mutant KRAS proteins, particularly G12V mutation, G12D mutation, and G12C mutation KRAS proteins, which can be used as drugs constituting the antibody-drug conjugate or salt thereof of the present invention, are shown below. (31-1-1) A heterocyclic compound having a mutant KRAS protein degradation-inducing activity, represented by the following formula (TP-1), (TP-2) or (TP-3): (In the formula, A is CR A , or N, R A is H or C 1-3 is alkyl, X 1 is —CH— or —O—, R 1 represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R1a is H, methyl, F or Cl, R 1b is F, Cl, methyl or ethyl, R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 is alkyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII), R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, R 3b is H or C 1-3 is alkyl, R 3c and R 3d is -(CH2) p CHR3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, However, R 3c -(CH2) p CHR 3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 alkyl)-, R 3e -OC 2-3 Alkylene-NR N1 R N2 and R 3f is H, F or C 1-3 is alkyl, R 3g is H or C 1-3 is alkyl, R 3h is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms; R 3i are the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２ , a group selected from the group consisting of halogen, -CN, and oxo; or Two R's on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two adjacent carbon atoms 3i together with the two carbon atoms to form C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two non-adjacent carbon atoms 3i may form a bridged structure consisting of 1 to 2 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C 1-3 Alkyl, -O-(C 1-3 optionally substituted with 1 to 2 groups selected from the group consisting of alkyl), OH, halogen, and oxo; RN1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2 may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 may form, together with the carbon atom and nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen, X 2 is -O-, -NH-, or -N(C 1-3 alkyl)-, X 3 is O or S, X 4 is -CH2-, -CH2-CH2-, or -O-CH2-, n is 1 or 2, p is 1 or 2; q is an integer from 1 to 8; R 4 F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4a pyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4a C optionally substituted with F 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3is alkyl, Y is phenylene optionally substituted with F or Cl, or pyridinediyl; L P is a group that chemically bonds Y and EUB, EUB is a group capable of binding to E3 ubiquitin ligase, R 8 is H or halogen.) (31-1-2) A heterocyclic compound represented by formula (TP-1) having an activity of inducing the degradation of mutant KRAS protein. (31-1-3) A heterocyclic compound represented by formula (TP-2) having an activity of inducing the degradation of mutant KRAS protein. (31-1-4) A heterocyclic compound represented by formula (TP-3) having an activity of inducing the degradation of mutant KRAS protein. Heterocyclic compounds having the effect of inducing mutant KRAS protein degradation, represented by the following formulas (TP-4) to (TP-11) (see WO 2023 / 099620. For symbols in the figure, refer to the patent document). Heterocyclic compounds having the effect of inducing mutant KRAS protein degradation, represented by the following formulas (TP-12) to (TP-16) (see WO 2023 / 141570. For symbols in the figure, refer to the patent document). A heterocyclic compound having the effect of inducing mutant KRAS protein degradation, represented by the following formula (TP-17) or (TP-18) (see WO 2023 / 130012; for the symbols in the formula, see WO 2023 / 130012). 2. Linker (L A ) As used herein, the linker (L) constituting the antibody-drug conjugate or salt thereof of the present invention A ) is a bifunctional moiety that attaches one or more drugs (D) to an antibody (Ab) to form an antibody-drug conjugate. A In some embodiments, the linker (D) is a linker that is cleavable or non-cleavable in vivo, and in some embodiments, it is a linker that is cleavable in vivo. A linker that is cleavable in vivo is a linker that has a partial structure that is cleavable in vivo, and is not particularly limited to a linker that has a partial structure that is cleavable by an enzyme such as a protease, glycosidase, esterase, or phosphatase. Examples of proteases include cathepsin B, cathepsin S, plasmin, and legumain. Examples of glycosidases include β-glucuronidase and β-galactosidase. Examples of esterases include, but are not limited to, carboxyesterase. Cleavage of the linker releases the drug (D) in vivo. In the present invention, L A Some embodiments of the bonding mode between and D are shown below. (32-1)L A is bonded to any nitrogen atom or oxygen atom of —OH contained in D, and when the nitrogen atom is a tertiary amine, the nitrogen atom is bonded to L A It combines with to form a quaternary ammonium salt. (32-2) L A is the group R 3 , R 4 or NL bonded to the nitrogen atom of the amine or the oxygen atom of -OH contained in EUB A Or office worker A where, if the amine is a tertiary amine, the nitrogen atom of the amine is L A It combines with to form a quaternary ammonium salt. (32-3) L A is the group R3 or R 4 or the oxygen atom of -OH in EUB. A Or office worker A where, if the amine is a tertiary amine, the nitrogen atom of the amine is L A It combines with to form a quaternary ammonium salt. (32-4) L A is the group R 3 or R 4 NL is bonded to the nitrogen atom of the amine contained in A where, if the amine is a tertiary amine, the nitrogen atom of the amine is L A It combines with to form a quaternary ammonium salt. (32-5) L A is the group R 3 NL is bonded to the nitrogen atom of the amine contained in A where, if the amine is a tertiary amine, the nitrogen atom of the amine is L A It combines with to form a quaternary ammonium salt. (32-6)L A is the group R 4 NL is bonded to the nitrogen atom of the amine contained in A where, if the amine is a tertiary amine, the nitrogen atom of the amine is L A It combines with to form a quaternary ammonium salt. (32-7) L A is the group R 4 N(R 4a )2 bonded to the nitrogen atom -N + (R 4a )2-L A Form. (32-8)L A is bonded to the oxygen atom of -OH contained in the group EUB that D has, and A Form. (32-9) L A is bonded to any nitrogen atom contained in D, and if the nitrogen atom is a tertiary amine, the nitrogen atom is AIt combines with to form a quaternary ammonium salt. The linker (L A ) is shown below. (33-1) A linker for linking Ab and D. (33-2) A linker represented by the following formula (XV): (In the formula, Str is the stretcher unit, which binds to Ab and CLL; CLL is a partial structure that can be cleaved in vivo. Sp is a spacer unit and binds to CLL and D; t is 0 or 1; *Ab indicates the binding site with Ab. (34-1) The linker according to (33-2), wherein r is 1. (34-2) The linker according to (33-2), wherein r is 0. (35-1) The linker according to (33-2), wherein t is 1. (35-2) The linker according to (33-2), wherein t is 0. As used herein, a "stretcher unit (Str)" is a structural unit that, when present, connects an antibody (Ab) to CLL. The stretcher unit forms a covalent bond with a functional group contained in the antibody (Ab). Functional groups contained in the antibody (Ab) that form a covalent bond with the stretcher unit include, but are not limited to, a mercapto group, an amino group, a hydroxyl group, and a carboxyl group, and in one embodiment, a mercapto group. Mercapto groups that can be used to form covalent bonds with drug-linker conjugates can also be generated by reducing intramolecular disulfide bonds contained in the antibody. One embodiment of a stretcher unit (Str) is shown below. (36-1) Stretcher unit represented by formula (ST-1) (In the formula, R st1 may be substituted C 1-12 alkylene, or optionally substituted C 1-50 is heteroalkylene, *Abindicates the binding site with Ab). (36-1-2) R st1 may be substituted C 1-12 alkylene, -optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a -, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 The stretcher unit according to (36-1), wherein a is alkylene- and a is an integer of 1 to 10. (36-1-3) R st1 -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 The stretcher unit according to (36-1), which is alkylene-. (36-2) R st1 may be substituted C 1-12 alkylene, or optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - and The stretcher unit according to (36-1), wherein a is an integer of 1 to 10. (36-3) R st1 is C 1-12 The stretcher unit according to (36-1), which is alkylene. (36-4) R st1 is C 3-8 The stretcher unit according to (36-1), which is alkylene. (36-5) R st1 is a C5 alkylene, the stretcher unit according to (36-1). (36-6)R st1 may be substituted C 1-50 The stretcher unit according to (36-1), which is a heteroalkylene. (36-7) R st1 is optionally substituted C1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - and a is an integer of 1 to 10. The stretcher unit according to (36-1). (36-8) The stretcher unit according to (36-7), wherein a is an integer of 3 to 9. (36-9) The stretcher unit according to (36-7), wherein a is an integer of 5 to 8. (36-10) Stretcher unit represented by formula (ST-2) or (ST-3) (In the formula, R st1 may be substituted C 1-12 alkylene, or optionally substituted C 1-50 is heteroalkylene, *Ab indicates the binding site with Ab). (36-10-2) R st1 may be substituted C 1-12 alkylene, -optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a -, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 The stretcher unit according to (36-10), wherein a is alkylene- and a is an integer of 1 to 10. (36-10-3) R st1 -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 The stretcher unit according to (36-10), which is alkylene-. (36-11) R st1 may be substituted C 1-12 alkylene, or optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a- and a is an integer of 1 to 10. The stretcher unit according to (36-10). (36-12) R st1 is C 1-12 The stretcher unit according to (36-10), which is alkylene. (36-13) R st1 is C 3-8 The stretcher unit according to (36-10), which is alkylene. (36-14)R st1 is a C5 alkylene, the stretcher unit according to (36-10). (36-15)R st1 may be substituted C 1-50 The stretcher unit according to (36-10), which is a heteroalkylene. (36-16)R st1 is optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - and a is an integer of 1 to 10. The stretcher unit according to (36-10). (36-17) The stretcher unit according to (36-16), wherein a is an integer of 3 to 9. (36-18) The stretcher unit according to (36-16), wherein a is an integer of 5 to 8. (36-19) Stretcher unit represented by formula (ST-1) (In the formula, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; *Ab indicates the binding site with Ab). (36-20)R st1 may be substituted C 1-12 The stretcher unit according to (36-19), which is alkylene-NH-. (36-21)R st1 may be substituted C 3-8 The stretcher unit according to (36-19), which is alkylene-NH-. (36-22)R st1 is an optionally substituted C5 alkylene-NH-. (36-23)R st1 -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 The stretcher unit according to (36-19), which is alkylene-NH-. (36-24)R st1 -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 The stretcher unit according to (36-19), which is alkylene-NH-. (36-25)R st1 -C1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 The stretcher unit according to (36-19), which is alkylene-NH-. (36-26)R PEG is -C(=O)-(CH2CH2O) b The stretcher unit according to (36-1-2), (36-1-3), (36-10-2), (36-10-3), (36-19), (36-23), (36-24), or (36-25), wherein the stretcher unit is —CH3. (36-26-2) b is an integer of 2 to 20, (36-1-2), (36-1-3), (36-10-2), (36-10-3), (36-19), (36-23), (36-24), or (36-25). (36-27) b is an integer of 5 to 15, (36-1-2), (36-1-3), (36-10-2), (36-10-3), (36-19), (36-23), (36-24), or (36-25). (36-28) The stretcher unit according to (36-1-2), (36-1-3), (36-10-2), (36-10-3), (36-19), (36-23), (36-24), or (36-25), wherein b is an integer of 10 to 12. (36-29) b is 12, (36-1-2), (36-1-3), (36-10-2), (36-10-3), (36-19), (36-23), (36-24), or (36-25). In the present invention, embodiments of the "in vivo cleavable partial structure (CLL)" are shown below. (37-1) A partial structure cleavable in vivo, represented by formula (CL-1) (In the formula, R AAare each independently H, methyl, isopropyl, isobutyl, sec-butyl, benzyl, p-hydroxybenzyl, hydroxymethyl, 1-hydroxyethyl, -CH2-C(=O)-OH, -(CH2)2-C(=O)-OH, -CH2-C(=O)-NH2, -(CH2)2-C(=O)-NH2, -(CH2)4-NH2, -(CH2)3-NH-C(=NH)-NH2, -(CH2)3-NH-C(=O)-NH2, -CH2-SH, or -CH2-S-CH3, or a group selected from the group consisting of the following formulae (RAA-1) and (RAA-2), d is an integer from 1 to 6, *STR indicates the binding site with Str). (37-2) R AA are each independently H, methyl, isopropyl, benzyl, -(CH2)4-NH2, -(CH2)3-NH-C(=NH)-NH2, or -(CH2)3-NH-C(=O)-NH2, and d is an integer of 2 to 4. (37-3) R AA are each independently a group selected from the group consisting of H, methyl, isopropyl, benzyl, and —(CH)—NH—C(═O)—NH, and d is an integer of 2 to 4. (37-4) R AA are each independently methyl, isopropyl, or —(CH2)3—NH—C(═O)—NH2, and d is 2. (37-5) R AA are each independently methyl or isopropyl, and d is 2. (37-6) R AA are each independently isopropyl or —(CH2)3—NH—C(═O)—NH2, and d is 2. (37-7) A partial structure cleavable in vivo, represented by formula (CL-2): (In the formula, *STR indicates the binding site with Str). (37-8) A partial structure cleavable in vivo, represented by formula (CL-3) (In the formula, *STR indicates the binding site with Str). As used herein, the term "spacer unit (Sp)" refers to a structural unit that connects CLL to a drug (D). In one embodiment, the spacer unit binds to the nitrogen atom of an amine or the oxygen atom of -OH contained in the drug (D) to form N-Sp or O-Sp, and in another embodiment, R 3 , R 4 or bonded to the nitrogen atom of the amine or the oxygen atom of —OH contained in EUB to form N-Sp or O-Sp, and in one embodiment, R 3 or R 4 or the oxygen atom of —OH contained in EUB to form N-Sp or O-Sp, and in one embodiment, 4 N(R 4a )2 to form N-Sp. If the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium. One embodiment of the spacer unit is a self-immolative spacer unit. A self-immolative spacer unit decomposes on its own, without further hydrolysis, to release the free drug (D) upon cleavage of the CLL. Certain embodiments of spacer units are shown below. (38-1) Spacer units represented by formula (SP-1), formula (SP-2) or formula (SP-3) (In the formula, R SP is H, C 1-6 Alkyl, -OC 1-6 Alkyl, halogen, or halogenoC 1-6 is alkyl, *CLL indicates the junction with CLL). (38-2) R SP is H. The spacer unit according to (38-1). (38-3) Spacer unit represented by formula (SP-1) (In the formula, R SP is H, C 1-6 Alkyl, -OC 1-6 Alkyl, halogen, or halogenoC 1-6 is alkyl, *CLL indicates the junction with CLL. (38-4) R SP is H. The spacer unit according to (38-3). (38-5) Spacer unit represented by formula (SP-2) (In the formula, *CLL indicates the junction with CLL. (38-6) Spacer unit represented by formula (SP-3) (In the formula, R SP is H, C 1-6 Alkyl, -OC 1-6 Alkyl, halogen, or halogenoC 1-6 is alkyl, *CLL indicates the junction with CLL. (38-7) R SP is H. The spacer unit according to (38-6). (38-8) Spacer unit represented by formula (SP-4) (In the formula, *CLL indicates the junction with CLL. Without being bound by the following theory, it is believed that the self-immolative spacer unit (SP-1) used in the present invention decomposes via the following mechanism after the bond between CLL and the nitrogen atom is cleaved, thereby releasing the drug (D) (Journal of Organic Chemistry, 2002, 67, pp. 1866-1872). The linker L constituting the antibody-drug conjugate or salt thereof of the present invention A Some aspects of this are shown below. (39-1) A linker represented by formula (XV) (In the formula, Str is the stretcher unit, which binds to Ab and CLL; CLL is a partial structure that can be cleaved in vivo. Sp is a spacer unit, which binds to CLL and D, and t is 0 or 1; where: i) Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 alkylene, or optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a and a is an integer from 1 to 10; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-1), *STR indicates the binding site with Str, R AA are each independently a radical selected from the group consisting of H, methyl, isopropyl, benzyl, and —(CH)—NH—C(═O)—NH, d is an integer from 2 to 4, Sp is a spacer unit represented by formula (SP-1), formula (SP-2) or formula (SP-3), t is 1, *CLL indicates the binding site with CLL, R SP is H, Or, ii) Str is a stretcher unit represented by formula (ST-1), and r is 1; *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-2), *STR indicates the binding site with Str, t is 0, *Ab indicates the binding site with Ab). (39-2) Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-2),*STR indicates the binding site with Str, The linker according to (39-1), wherein t is 0. (39-3) R st1 -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 The linker according to (39-2), which is alkylene-NH-. (39-4) R st1 -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 The linker according to (39-3), which is alkylene-NH-. (39-5) R st1 -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 The linker according to (39-3), which is alkylene-NH-. (39-6) A linker represented by the following formula (LA-1): *Ab indicates the Ab binding site). (39-7) A linker represented by the following formula (LA-2): *Ab indicates the Ab binding site). (39-8) A linker represented by the following formula (LA-3): (wherein b is an integer of 2 to 20, *Ab indicates the Ab binding site). (39-9) A linker represented by the following formula (LA-4): (wherein b is an integer of 2 to 20, *Ab indicates the Ab binding site). (39-10) A linker represented by the following formula (LA-5): *Ab indicates the Ab binding site). (39-11) The linker according to (39-8) or (39-9), wherein b is an integer of 5 to 15. (39-12) The linker according to (39-8) or (39-9), wherein b is an integer of 10 to 12. (39-13) The linker according to (39-8) or (39-9), wherein b is 12. Furthermore, the linker L constituting the antibody-drug conjugate or salt thereof of the present invention A Another example is shown below: A linker represented by the following formula (LA-6) or formula (LA-7) (see WO 2015 / 095124, wherein: *Ab indicates the binding site with Ab. A linker represented by the following formula (LA-8) (see WO 2015 / 095223, wherein: *Ab indicates the binding site with Ab. A linker represented by the following formula (LA-9) (see WO 2015 / 095227, wherein: *Ab indicates the binding site with Ab. A linker represented by the following formula (LA-10) (see WO 2014 / 057687, wherein: *Ab indicates the binding site with Ab. A linker represented by the following formula (LA-11) (see WO 2013 / 173337, wherein: *Ab indicates the binding site with Ab. A linker represented by the following formula (LA-12) (see WO 2022 / 220625, wherein: *Abindicates the binding site with Ab. A linker represented by the following formula (LA-13) (see WO 2016 / 040684, wherein: *Ab indicates the binding site with Ab. A linker represented by the following formula (LA-14) or formula (LA-15) (see WO 2015 / 057699, wherein e represents an integer of 2 to 24, *Ab indicates the binding site with Ab. 3. Drug-linker conjugates (L A -D) As used herein, a "drug-linker conjugate" refers to a drug-linker conjugate that is A ) and a drug (D) are covalently bonded to each other. The drug-linker conjugate of the present invention or a salt thereof has a reactive site and can react with a functional group contained in an antibody (Ab) to form a covalent bond, and is useful as an intermediate for synthesizing an antibody-drug conjugate. In this antibody-drug conjugate, at least one drug-linker conjugate of the present invention is bound to an antibody (Ab). In one embodiment, the antibody-drug conjugate may further have at least one other drug (such as an anticancer drug, a proteolysis inducer, an immunostimulant, or a label) bound to the antibody portion and / or linker portion via a linker. The functional group contained in the antibody (Ab) that forms a covalent bond with the drug-linker conjugate or a salt thereof of the present invention is not particularly limited, but examples thereof include a mercapto group, an amino group, a hydroxyl group, and a carboxyl group, and in one embodiment, a mercapto group. A mercapto group that can be used to form a covalent bond with the drug-linker conjugate can also be generated by reducing an intramolecular disulfide bond contained in the antibody. For example, when the drug-linker conjugate or a salt thereof of the present invention has a maleimide structure, it reacts with a mercapto group contained in an antibody to form the following partial structure, thereby synthesizing the antibody-drug conjugate or a salt thereof of the present invention (wherein Ab'-SH represents an antibody having a mercapto group). In the present invention, certain embodiments of the binding mode between Sp and D are shown below. When t is 0, Sp does not exist, and CLL directly binds to D instead of Sp in the following embodiments. (40-1) Sp bonds to any nitrogen atom or oxygen atom of —OH contained in D, and if the nitrogen atom is a tertiary amine, the nitrogen atom bonds with Sp to form a quaternary ammonium. (40-2) Sp is a group R 3 , R 4 Or it bonds to the nitrogen atom of the amine or the oxygen atom of -OH contained in EUB to form N-Sp or O-Sp, and if the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium. (40-3) Sp is a group R 3 or R 4 or the oxygen atom of —OH contained in EUB to form N-Sp or O-Sp, and if the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium. (40-4) Sp is a group R that D has. 3 or R 4 to form N-Sp, and if the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium. (40-5) Sp is a group R 3 to form N-Sp, and if the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium. (40-6) Sp is a group R 4 to form N-Sp, and if the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium. (40-7) Sp is a group R 4 N(R 4a )2 bonded to the nitrogen atom -N +(R 4a )2-Sp is formed. (40-8) Sp bonds to the oxygen atom of —OH contained in the group EUB of D to form O—Sp. (40-9) Sp bonds to any nitrogen atom contained in D, and if the nitrogen atom is a tertiary amine, the nitrogen atom bonds with Sp to form a quaternary ammonium. Embodiments of the drug-linker conjugate or a salt thereof of the present invention are shown below. (41-1) A drug-linker conjugate represented by formula (LD-1) or a salt thereof (In the formula, D is a heterocyclic compound that induces the degradation of mutant KRAS proteins, R st1 may be substituted C 1-12 Alkylene or optionally substituted C 1-50 is heteroalkylene, CLL is a partial structure that can be cleaved in vivo. Sp is a spacer unit and binds to CLL and D; t is 0 or 1; Sp bonds to the nitrogen atom of the amine or the oxygen atom of -OH in D to form N-Sp or O-Sp, where if the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium). (41-2) D is a heterocyclic compound represented by formula (II) having an activity of inducing mutant KRAS protein degradation, A is CR A , or N, R A is H or C 1-3 is alkyl, X 1 is —CH— or —O—, R 1 represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R 1a is H, methyl, F or Cl, R 1b is F, Cl, methyl or ethyl, R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 is alkyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII), R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, R 3b is H or C 1-3 is alkyl, R 3c and R 3d is -(CH2) p CHR 3f -NR N1 RN2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, However, R 3c -(CH2) p CHR 3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 alkyl)-, R 3e -OC 2-3 Alkylene-NR N1 R N2 and R 3f is H, F or C 1-3 is alkyl, R 3g is H or C 1-3 is alkyl, R 3h is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms; R 3iare the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２ , a group selected from the group consisting of halogen, -CN, and oxo; or Two R's on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 2 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two adjacent carbon atoms 3i together with the two carbon atoms to form C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two non-adjacent carbon atoms 3i may form a bridged structure consisting of 1 to 2 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C 1-3 Alkyl, -O-(C 1-3 optionally substituted with 1 to 2 groups selected from the group consisting of alkyl), OH, halogen, and oxo; R N1 and R N2are the same or different and are H or C 1-3 alkyl, or R N1 and R N2 may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 may form, together with the carbon atom and nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen, X 2 is -O-, -NH-, or -N(C 1-3 alkyl)-, X 3 is O or S, X 4 is -CH2-, -CH2-CH2-, or -O-CH2-, n is 1 or 2, p is 1 or 2; q is an integer from 1 to 8; R 4 F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4a pyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4a C optionally substituted with F 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3 is alkyl, Y is phenylene optionally substituted with F or Cl, or pyridinediyl; L P is a group that chemically bonds Y and EUB, EUB is a group capable of binding to E3 ubiquitin ligase, CLL is a partial structure that can be cleaved in vivo. Sp is a spacer unit, which binds to CLL and D, and t is 0 or 1; Sp is a group R carried by D. 3 , R 4 or NL bonded to the nitrogen atom of the amine or the oxygen atom of -OH contained in EUB A Or office worker A wherein, if the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium; where: i) R st1 may be substituted C 1-12 alkylene, -optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - or -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 alkylene-, and a is an integer from 1 to 10; R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure represented by formula (CL-1') that can be cleaved in vivo, *CO indicates the bond to the carbonyl group, R AAare each independently a radical selected from the group consisting of H, methyl, isopropyl, benzyl, and —(CH)—NH—C(═O)—NH, d is an integer from 2 to 4, Sp is a spacer unit represented by formula (SP-1), formula (SP-2) or formula (SP-3), t is 1, *CLL indicates the binding site with CLL, R SP is H, Or, ii) R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure represented by formula (CL-2') that can be cleaved in vivo, *CO indicates the bond to the carbonyl group, The drug-linker conjugate or salt thereof according to (41-1), wherein t is 0. (41-3) EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5is methyl, ethyl, isopropyl, isobutyl, sec-butyl, tert-butyl, C 3-6 cycloalkylmethyl, or C 3-6 is cycloalkyl, R 6a and R 6b are the same or different and may be substituted with H or a group selected from the group consisting of OH, OCH3, and N(CH3)2; 1-6 alkyl, or R 6a , R 6b may be substituted together with the carbon to which they are attached. 3-6 It may form a cycloalkane or an optionally substituted 4- to 6-membered saturated heterocycle containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen as ring-constituting atoms, R 7 is an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or a 6-membered heteroaryl containing 1 to 3 nitrogen atoms, W is an optionally substituted phenylene or an optionally substituted 6-membered heteroarenediyl containing 1 to 3 nitrogen atoms as ring-constituting atoms; L P is -(L 1 -L 2 -L 3 -L 4 )- and L 1 , L 2 , L 3 , L 4 are the same or different and represent a bond, -O-, -NR L1 -, optionally substituted pyrrolidinediyl, optionally substituted piperidinediyl, optionally substituted piperazinediyl, optionally substituted C 1-3 a group selected from the group consisting of alkylene and C═O; R L1 is H or C1-3 is alkyl, The drug-linker conjugate or salt thereof according to (41-2), wherein Z is NH or a 5-membered heteroarenediyl containing, as ring-constituting atoms, 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen. (41-4) A is CR A , or N, R A is H, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), and (XI): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, R 3f is H, R N1 and R N2 are the same or different and are H or C 1-3 It is an alkyl X 2 is —O— or —NH—, X 3 is O, n is 1, p is 1, R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 is alkyl, The drug-linker conjugate or a salt thereof according to (41-3), wherein Y is phenylene. (41-4-1) EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen; W is phenylene; L P is a bond, Z is a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms; Sp is a group R carried by D. 3 or R 4 or the oxygen atom of —OH contained in EUB to form N-Sp or O-Sp, and when the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium. (41-5) A is N, R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3is alkyl, R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): Z is a group represented by the following formula (XVII): R st1 may be substituted C 1-12 Alkylene, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure represented by formula (CL-2') that can be cleaved in vivo, *CO indicates the bond to the carbonyl group, t is 0, Sp is R 4 N(R 4a )2 bonded to the nitrogen atom -N + (R 4a )2-Sp is formed, or a salt thereof according to (41-4). (41-6) A is CR A , or N, R A is H, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2is cyclopropyl, R 3 is a group selected from the group consisting of the following formula (IV-a) and formula (Va): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, R 3f is H, R N1 and R N2 are the same or different and are H or C 1-3 is alkyl, X 2 is —O— or —NH—, X 3 is O, p is 1, n is 1, R 4 C may be substituted with OCH3 1-6 is alkyl, Y is phenylene; L P is a bond, EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl, R 6a is H and R 6b is hydroxymethyl, R 7 is a group selected from the group consisting of the following formula (XIX-a) and formula (XVI), W is a group represented by formula (XVII-a), Z is a group represented by the following formula (XVIII-a): * L P ) Sp is a group R carried by D. 3 or the oxygen atom of —OH contained in EUB to form N-Sp or O-Sp, and when the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium. (41-7) A drug-linker conjugate or a salt thereof according to any one of (41-1) to (41-6), wherein D is a heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by the following formula (PL-1) (wherein *Sp represents the bond to Sp): (41-8) A drug-linker conjugate or a salt thereof according to any one of (41-1) to (41-7), which is represented by the following formula (LD-2′): (wherein b is an integer from 2 to 20). (41-9) A drug-linker conjugate or a salt thereof according to any one of (41-1) to (41-7), which is represented by the following formula (LD-3′): (wherein b is an integer from 2 to 20). (41-10) A drug-linker conjugate or a salt thereof according to any one of (41-1) to (41-7), which is represented by the following formula (LD-4'): (41-11) A drug-linker conjugate or a salt thereof represented by the following formula (LD-2), (LD-3) or (LD-4): (wherein b is an integer from 2 to 20). (41-12) The drug-linker conjugate or salt thereof according to any one of (41-2) to (41-11), wherein b is an integer of 5 to 15. (41-13) The drug-linker conjugate or salt thereof according to (41-2) to (41-11), wherein b is an integer of 10 to 12. (41-14) The drug-linker conjugate or salt thereof according to (41-2) to (41-11), wherein b is 12. (41-15) A drug-linker conjugate represented by formula (LD-8) or a salt thereof (In the formula, D is a heterocyclic compound represented by formula (II) having an activity of inducing mutant KRAS protein degradation, A is CR A , or N, R A is H or C 1-3 is alkyl, X 1 is —CH— or —O—, R 1 represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R 1a is H, methyl, F or Cl, R 1b is F, Cl, methyl or ethyl, R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 is alkyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII), R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, R 3b is H or C 1-3 is alkyl, R 3c and R 3d is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, However, R 3c -(CH2) p CHR3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 alkyl)-, R 3e -OC 2-3 Alkylene-NR N1 R N2 and R 3f is H, F or C 1-3 is alkyl, R 3g is H or C 1-3 is alkyl, R 3h is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms; R 3i are the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２ , a group selected from the group consisting of halogen, -CN, and oxo; or Two R's on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two adjacent carbon atoms 3i together with the two carbon atoms to form C 3-6A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two non-adjacent carbon atoms 3i may form a bridged structure consisting of 1 to 2 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C 1-3 Alkyl, -O-(C 1-3 optionally substituted with 1 to 2 groups selected from the group consisting of alkyl), OH, halogen, and oxo; R N1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2 may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 may form, together with the carbon atom and nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen, X 2 is -O-, -NH-, or -N(C 1-3 alkyl)-, X 3 is O or S, X 4 is -CH2-, -CH2-CH2-, or -O-CH2-, n is 1 or 2, p is 1 or 2; q is an integer from 1 to 8; R 4 F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4a pyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4a C optionally substituted with F 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3 is alkyl, Y is phenylene optionally substituted with F or Cl, or pyridinediyl; L P is a group that chemically bonds Y and EUB, EUB is a group capable of binding to E3 ubiquitin ligase, CLL is a partial structure that can be cleaved in vivo and is represented by the formula (CL-3). (In the formula, *STR indicates the binding site with Str), Sp is a spacer unit represented by formula (SP-4) (In the formula, *CLL indicates the binding site to CLL. ), binds to CLL and D, t is 1, Sp bonds to the oxygen atom of -OH contained in EUB to form O-Sp). (41-16) D is a heterocyclic compound represented by formula (II) having an activity of inducing mutant KRAS protein degradation, A is N, X 1 is -O-, R1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3 is alkyl, Y is phenylene; L P is a bond, EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): The drug-linker conjugate or salt thereof according to (41-1), wherein Z is a group represented by the following formula (XVIII): 4. Antibodies or antigen-binding fragments (Abs) The antibody or antigen-binding fragment (hereinafter also referred to as "Ab") used in the present invention binds to an antigen protein or a modified form thereof (e.g., glycosylation) expressed on a cell surface. In one embodiment, the antibody or antigen-binding fragment used in the present invention binds to a tumor-associated antigen or cell surface receptor expressed on the surface of a cancer cell. In some embodiments, the antibody or antigen-binding fragment used in the present invention is selected from the group consisting of 5T4, ADAM9, ALPP, ALPPL2, AXL, B7H3, B7H4, BCMA, CA9, CCR2, CCR7, CD123, CD166, CD19, CD20, CD22, CD25, CD30, CD33, CD37, CD38, CD45, CD46, CD70, CD74, CD79b, CDH3, CDH6, CEACAM5, CEACAM6, CLDN1, CLDN4, CLDN6, CLDN18.2, cMET, EGFR, EphA3, FAP, FGFR3, Fibronectin, FOLRa, Globo H, GPRC5D, HER2, HER3, IGF1R, and Integrin. The antibody or antigen-binding fragment may be an antibody or antigen-binding fragment that binds to one or more antigens selected from the group consisting of αV, KAAG1, LIV1, MSLN, MT1-MMP, MUC1, MUC4, NaPi2b, Nectin-4, PD-L1, PSMA, PTK7, ROR1, ROR2, SEZ6, SialylTn, TF, TROP2, TSPAN8, or VEGF. In one embodiment, the antibody or antigen-binding fragment used in the present invention is an antibody or antigen-binding fragment that binds to one or more antigens selected from the group consisting of 5T4, B7H3, CEACAM5, CEACAM6, CLDN4, CLDN18.2, cMET, EGFR, HER2, HER3, MUC1, TROP2, or TSPAN8. In another embodiment, the antibody or antigen-binding fragment used in the present invention is an antibody or antigen-binding fragment that binds to one or more antigens selected from the group consisting of EGFR, HER2, Nectin-4, and TROP2. In one embodiment, the antibody or antigen-binding fragment used in the present invention is an antibody or antigen-binding fragment that binds to EGFR. In one embodiment, the antibody or antigen-binding fragment used in the present invention is an anti-5T4 antibody, an anti-ADAM9 antibody, an anti-ALPP antibody, an anti-ALPPL2 antibody, an anti-AXL antibody, an anti-B7H3 antibody, an anti-B7H4 antibody, an anti-BCMA antibody, an anti-CA9 antibody, an anti-CCR2 antibody, an anti-CCR7 antibody, an anti-CD123 antibody, an anti-CD166 antibody, an anti-CD19 antibody, an anti-CD20 antibody, an anti-CD22 antibody, an anti-CD25 antibody, an anti-CD30 antibody, an anti-CD33 antibody, an anti-CD37 antibody, an anti-CD40 antibody, an anti-CD41 antibody, an anti-CD42 antibody, an anti-CD43 antibody, an anti-CD44 antibody, an anti-CD45 antibody, an anti-CD46 antibody, an anti-CD47 antibody, an anti-CD48 antibody, an anti-CD49 antibody, an anti-CD50 antibody, an anti-CD51 antibody, an anti-CD52 antibody, an anti-CD53 antibody, an anti-CD54 antibody, an anti-CD55 antibody, an anti-CD56 antibody, an anti-CD57 antibody, an anti-CD58 antibody, an anti-CD59 antibody, an anti-CD60 antibody, an anti-CD61 antibody, an anti-CD62 antibody, an anti-CD63 antibody, an anti-CD64 antibody, an anti-CD65 antibody, an anti-CD66 antibody, an anti-CD67 antibody, an anti-CD68 antibody, an anti-CD69 antibody, an anti-CD70 antibody, an anti-CD71 antibody, an anti-CD72 antibody, an anti-CD73 antibody, an anti-CD74 antibody, an anti-CD75 antibody, an anti-CD76 antibody, an anti-CD77 antibody, an anti-CD78 antibody, an anti-CD79 antibody, an anti-CD80 antibody, an anti-CD8 CD38 antibody, anti-CD45 antibody, anti-CD46 antibody, anti-CD70 antibody, anti-CD74 antibody, anti-CD79b antibody, anti-CDH3 antibody, anti-CDH6 antibody, anti-CEACAM5 antibody, anti-CEACAM6 antibody, anti-CLDN1 antibody, anti-CL DN4 antibody, anti-CLDN6 antibody, anti-CLDN18.2 antibody, anti-cMET antibody, anti-EGFR antibody, anti-EphA3 antibody, anti-FAP antibody, anti-FGFR3 antibody, anti-Fibronectin antibody, anti-FOLRa antibody, anti-Globo The antibody or antigen-binding fragment thereof may be selected from the group consisting of H antibody, anti-GPRC5D antibody, anti-HER2 antibody, anti-HER3 antibody, anti-IGF1R antibody, anti-Integrin αV antibody, anti-KAAG1 antibody, anti-LIV1 antibody, anti-MSLN antibody, anti-MT1-MMP antibody, anti-MUC1 antibody, anti-MUC4 antibody, anti-NaPi2b antibody, anti-Nectin-4 antibody, anti-PD-L1 antibody, anti-PSMA antibody, anti-PTK7 antibody, anti-ROR1 antibody, anti-ROR2 antibody, anti-SEZ6 antibody, anti-SialylTn antibody, anti-TF antibody, anti-TROP2 antibody, anti-TSPAN8 antibody, and anti-VEGF antibody. In one embodiment, the antibody or antigen-binding fragment used in the present invention is an antibody or antigen-binding fragment thereof selected from the group consisting of anti-5T4 antibody, anti-B7H3 antibody, anti-CEACAM5 antibody, anti-CEACAM6 antibody, anti-CLDN4 antibody, anti-CLDN18.2 antibody, anti-cMET antibody, anti-EGFR antibody, anti-HER2 antibody, anti-HER3 antibody, anti-MUC1 antibody, anti-TROP2 antibody, or anti-TSPAN8 antibody. In one embodiment, the antibody or antigen-binding fragment used in the present invention is an antibody or antigen-binding fragment thereof selected from the group consisting of anti-EGFR antibody, anti-HER2 antibody, anti-Nectin-4 antibody, and anti-TROP2 antibody. Those skilled in the art can obtain antibodies or antigen-binding fragments thereof for use in the present invention using known methods. For example, they can be obtained by immunizing an animal with an antigenic polypeptide and collecting and purifying the antibodies produced in vivo using methods commonly used in this field. The antigen source is not limited to humans; animals can also be immunized with antigens derived from non-human animals such as mice and rats. In this case, antibodies applicable to human diseases can be selected by testing the cross-reactivity of the obtained antibodies that bind to heterologous antigens with human antigens. Alternatively, monoclonal antibodies can be obtained by establishing hybridomas by fusing antibody-producing cells that produce antibodies against antigens with myeloma cells according to known methods (e.g., Kohler and Milstein, Nature (1975) 256, pp. 495-497; Kennet, R. ed., Monoclonal Antibodies, pp. 365-367, Plenum Press, NY (1980)). The antigen to be used for immunization can be obtained, for example, by introducing a gene encoding a desired protein or polypeptide into host cells using a vector or the like, expressing the gene, and purifying the expressed protein. Alternatively, antibodies can be obtained by immunizing an animal with cells that have been genetically engineered to express a desired protein, or with cells such as a cell line that endogenously expresses the antigen. Whether an antibody or antigen-binding fragment binds to an antigen can be confirmed using known methods for measuring binding activity, such as enzyme-linked immunosorbent assay (ELISA) and flow cytometry. The antibodies or antibody-binding fragments used in the present invention may be derived from any species, including humans, rats, mice, and rabbits. If the antibodies are derived from species other than humans, they are preferably chimerized or humanized using well-known techniques. The antibodies or antibody-binding fragments used in the antibody-drug conjugates of the present invention may be polyclonal or monoclonal. In one embodiment, the antibody or antibody-binding fragment used in the present invention is an IgG-type antibody or antibody-binding fragment. IgG exists as subtypes, IgG1, IgG2, IgG3, and IgG4, depending on the structure of the hinge region and Fc region, and one skilled in the art can select an appropriate subtype taking into account the effector function, DAR, etc. of the antibody. In one embodiment, the antibody or antibody-binding fragment used in the present invention is an IgG1 or IgG4 type. In one embodiment, the antibody or antibody-binding fragment used in the present invention is an anti-EGFR antibody or antigen-binding fragment thereof. In one embodiment, the antibody or antibody-binding fragment used in the present invention is an anti-EGFR antibody or antigen-binding fragment thereof comprising the heavy chain variable region and light chain variable region described in (1) or (2) below: (1) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 31 to 35 of SEQ ID NO: 1, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 65 of SEQ ID NO: 1, and CDR3 consisting of the amino acid sequence from amino acid numbers 98 to 108 of SEQ ID NO: 1; and a light chain variable region comprising a CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 2, a CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 2, and a CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 2; or (2) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 3, CDR2 consisting of the amino acid sequence of amino acids 50 to 65 of SEQ ID NO: 3, and CDR3 consisting of the amino acid sequence of amino acids 98 to 108 of SEQ ID NO: 3; and A light chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 4, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 4. In one embodiment, the antibody or antibody-binding fragment used in the present invention is an anti-EGFR antibody or antigen-binding fragment thereof comprising a heavy chain variable region and a light chain variable region selected from the group consisting of (1) to (3) below: (1) a heavy chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 119 of SEQ ID NO: 1 and a light chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 107 of SEQ ID NO: 2; (2) a heavy chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 119 of SEQ ID NO: 3 and a light chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 107 of SEQ ID NO: 4; and (3) A heavy chain variable region and a light chain variable region having at least 90% identity to the heavy chain variable region and the light chain variable region described in (1) or (2) above. In one embodiment, the antibody used in the present invention is an anti-EGFR antibody of the IgG1 or IgG4 type. In one embodiment, the antibody used in the present invention is an antibody that binds to EGFR, and may be, for example, cetuximab, panitumumab, or matuzumab, or an antibody obtained by modifying any of these sequences. Sequence-modified antibodies (hereinafter also referred to as "modified antibodies") refer to antibodies in which a portion of the amino acid sequence of the variable or constant region has been modified based on the amino acid sequence of a known antibody. Examples of modified cetuximab include the antibodies described in WO2007058823, WO2013134743, and WO2014166029. In one embodiment, the antibody used in the present invention is preferably cetuximab or a modified version thereof. In one embodiment, the Ab used in the present invention is an anti-EGFR antibody consisting of a heavy chain of SEQ ID NO: 1 and a light chain of SEQ ID NO: 2, or an anti-EGFR antibody consisting of a heavy chain of SEQ ID NO: 3 and a light chain of SEQ ID NO: 4. In another embodiment, the Ab used in the present invention is an anti-EGFR antibody consisting of a heavy chain of SEQ ID NO: 1 and a light chain of SEQ ID NO: 2. In another embodiment, the Ab used in the present invention is an anti-EGFR antibody consisting of a heavy chain of SEQ ID NO: 3 and a light chain of SEQ ID NO: 4. In some embodiments, the antibodies or antigen-binding fragments used in the present invention may be post-translationally modified, such as N-linked or O-linked glycosylation, N-terminal or C-terminal processing, deamidation, aspartic acid isomerization, or methionine oxidation. In the antibody or antibody-binding fragment used in the present invention, any amino acid residue may be substituted with cysteine or a non-natural amino acid. Substitution with cysteine can be performed using, for example, the methods described in WO2008141044 and WO2016040856. Substitution with a non-natural amino acid can be performed using, for example, the methods described in WO2010081111 and WO2013185115. The Fc region of the antibody used in the present invention may contain mutations that reduce antibody-dependent cellular cytotoxicity (ADCC) or complement-dependent cytotoxicity (CDC). L234A is a substitution of leucine with alanine at amino acid position 234 according to the EU index in the human Igγ1 constant region. L235A is a substitution of leucine with alanine at amino acid position 235 according to the EU index in the human Igγ1 constant region. The amino acid mutations L234A and L235A in the human Igγ1 constant region are referred to as "LALA mutations." This mutation is known to reduce antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity of antibodies (Mol. Immunol., 1992; Vol. 29: pp. 633-639). P331G or P331S is a substitution of proline with glycine or serine at amino acid position 331 according to the EU index in the human Igγ1 constant region. This mutation is known to reduce the CDC of the antibody (J. Immunol., 2000, Vol / 164(8), p.4178-4184). 5. Antibody-drug conjugates The antibody-drug conjugate or a salt thereof of the present invention is an antibody-drug conjugate or a salt thereof represented by the following formula (I): (In the formula, Ab is an antibody or antigen-binding fragment thereof; D is a heterocyclic compound that induces the degradation of mutant KRAS proteins, L Ais a linker for connecting Ab and D, m is a number between 1 and 20). m represents the compound to antibody ratio in the antibody-drug conjugate. Some embodiments of m are shown below. (42-1) An antibody-drug conjugate or a salt thereof, wherein m is a number of 1 to 20. (42-2) An antibody-drug conjugate or a salt thereof, wherein m is a number of 1 to 10. (42-3) An antibody-drug conjugate or a salt thereof, wherein m is a number of 2 to 10. (42-4) An antibody-drug conjugate or a salt thereof, wherein m is a number from 3 to 9. (42-5) An antibody-drug conjugate or a salt thereof, wherein m is a number of 2 to 6. (42-6) An antibody-drug conjugate or a salt thereof, wherein m is a number of 3 to 5. (42-7) An antibody-drug conjugate or a salt thereof, wherein m is a number of 6 to 10. (42-8) An antibody-drug conjugate or a salt thereof, wherein m is a number of 7 to 9. Embodiments of the antibody-drug conjugate or a salt thereof of the present invention are shown below. (43-1) D is a heterocyclic compound represented by formula (II) having an activity of inducing mutant KRAS protein degradation, A is CR A , or N, R A is H or C 1-3 is alkyl, X 1 is —CH— or —O—, R 1 represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R 1a is H, methyl, F or Cl, R 1b is F, Cl, methyl or ethyl, R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 is alkyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII), R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, R 3b is H or C 1-3 is alkyl, R 3c and R 3d is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 RN2 , and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, However, R 3c -(CH2) p CHR 3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 alkyl)-, R 3e -OC 2-3 Alkylene-NR N1 R N2 and R 3f is H, F or C 1-3 is alkyl, R 3g is H or C 1-3 is alkyl, R 3h is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms; R 3i are the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２, a group selected from the group consisting of halogen, -CN, and oxo; or Two R's on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two adjacent carbon atoms 3i together with the two carbon atoms to form C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo; or R on two non-adjacent carbon atoms 3i may form a bridged structure consisting of 1 to 2 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C 1-3 Alkyl, -O-(C 1-3 optionally substituted with 1 to 2 groups selected from the group consisting of alkyl), OH, halogen, and oxo; R N1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 may form, together with the carbon atom and nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen, X 2 is -O-, -NH-, or -N(C 1-3 alkyl)-, X 3 is O or S, X 4 is -CH2-, -CH2-CH2-, or -O-CH2-, n is 1 or 2, p is 1 or 2; q is an integer from 1 to 8; R 4 F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4a pyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4a C optionally substituted with F 1-3 is alkyl, R 4b is C substituted with 1 to 3 F 1-3 is alkyl, Y is phenylene optionally substituted with F or Cl, or pyridinediyl; L P is a group that chemically bonds Y and EUB, EUB is a group capable of binding to E3 ubiquitin ligase, L A is a linker for binding Ab to D, and is bound to any nitrogen atom or oxygen atom of —OH contained in D. When the nitrogen atom is a tertiary amine, the nitrogen atom is bound to L A and forming a quaternary ammonium salt. (43-2) L A is a linker for binding Ab to D, and D has a group R 3 , R 4 or NL bonded to the nitrogen atom of the amine or the oxygen atom of -OH contained in EUB A Or office worker A where, if the amine is a tertiary amine, the nitrogen atom of the amine is L A The antibody-drug conjugate or salt thereof according to (43-1), which binds to the above to form a quaternary ammonium. (43-3) A is CR A , or N, R A is H, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), and (XI): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, R 3fis H, R N1 and R N2 are the same or different and are H or C 1-3 It is an alkyl X 2 is —O— or —NH—, X 3 is O, n is 1, p is 1, R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 is alkyl, The antibody-drug conjugate or a salt thereof according to (43-2), wherein Y is phenylene. (43-4) A is N, R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3 The antibody-drug conjugate or a salt thereof according to (43-3), wherein the aryl group is alkyl. (43-5) The antibody-drug conjugate or a salt thereof according to (43-2), wherein EUB is a group capable of binding to VHL or CRBN. (43-6) The antibody-drug conjugate or a salt thereof according to (43-2), wherein EUB is a group capable of binding to CRBN. (43-7) The antibody-drug conjugate or a salt thereof according to (43-2), wherein EUB is a group capable of binding to VHL. (43-8) EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is methyl, ethyl, isopropyl, isobutyl, sec-butyl, tert-butyl, C 3-6 cycloalkylmethyl, or C 3-6 is cycloalkyl, R 6a and R 6b are the same or different and may be substituted with H or a group selected from the group consisting of OH, OCH3, and N(CH3)2; 1-6 alkyl, or R 6a , R 6b may be substituted together with the carbon to which they are attached. 3-6 It may form a cycloalkane or an optionally substituted 4- to 6-membered saturated heterocycle containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen as ring-constituting atoms, R 7 is an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or a 6-membered heteroaryl containing 1 to 3 nitrogen atoms, W is an optionally substituted phenylene or an optionally substituted 6-membered heteroarenediyl containing 1 to 3 nitrogen atoms as ring-constituting atoms; L P is -(L 1 -L 2 -L 3 -L 4 )- and L 1 , L 2 , L 3 , L 4 are the same or different and represent a bond, -O-, -NR L1 -, optionally substituted pyrrolidinediyl, optionally substituted piperidinediyl, optionally substituted piperazinediyl, optionally substituted C 1-3 a group selected from the group consisting of alkylene and C═O; RL1 is H or C 1-3 is alkyl, The antibody-drug conjugate or a salt thereof according to (43-7), wherein Z is NH or a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms. (43-9) EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen; W is phenylene; L P is a bond, The antibody-drug conjugate or a salt thereof according to (43-8), wherein Z is a 5-membered heteroarenediyl containing, as ring-constituting atoms, 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen. (43-10) R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): The antibody-drug conjugate or salt thereof according to (43-9), wherein Z is a group represented by the following formula (XVIII): (43-11) L A is a linker represented by formula (XV): (In the formula, Str is the stretcher unit, which binds to Ab and CLL; CLL is a partial structure that can be cleaved in vivo. Sp is a spacer unit, which binds to CLL and D, and t is 0 or 1; *Ab indicates the binding site with Ab. (43-12) ii) Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 alkylene, -optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - or -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 alkylene-, and a is an integer from 1 to 10; R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-1), *STR indicates the binding site with Str, R AA are each independently a radical selected from the group consisting of H, methyl, isopropyl, benzyl, and —(CH)—NH—C(═O)—NH, d is an integer from 2 to 4, Sp is a spacer unit represented by formula (SP-1), formula (SP-2), or formula (SP-3), t is 1, *CLL indicates the binding site with CLL, R SP is H, Or, ii) Str is a stretcher unit represented by formula (ST-1), and r is 1; *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-2), *STR indicates the binding site with Str, The antibody-drug conjugate or a salt thereof according to (43-11), wherein t is 0. (43-13) Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-2), *STR indicates the binding site with Str, The antibody-drug conjugate or a salt thereof according to (43-12), wherein t is 0. (43-14) A is CR A , or N, R A is H, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group selected from the group consisting of the following formulas (IV), (V), and (XI): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, R 3f is H, R N1 and R N2 are the same or different and are H or C 1-3 It is an alkyl X 2is —O— or —NH—, X 3 is O, n is 1, p is 1, R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 is alkyl, Y is phenylene; EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen; W is phenylene; L P is a bond, Z is a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms; L A is a linker represented by formula (XV) *Ab indicates the binding site with Ab), Str is the stretcher unit, which binds to Ab and CLL; CLL is a partial structure that can be cleaved in vivo. Sp is a spacer unit, which binds to CLL and D, and t is 0 or 1; where: i) Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 alkylene, -optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - or -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 alkylene-, and a is an integer from 1 to 10; R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-1), *STR indicates the binding site with Str, R AA are each independently a radical selected from the group consisting of H, methyl, isopropyl, benzyl, and —(CH)—NH—C(═O)—NH, d is an integer from 2 to 4, Sp is a spacer unit represented by formula (SP-1), formula (SP-2) or formula (SP-3), t is 1, *CLL indicates the binding site with CLL, R SP is H, Or, ii) Str is a stretcher unit represented by formula (ST-1), and r is 1; *Ab indicates the binding site with Ab, Rst1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-2), *STR indicates the binding site with Str, t is 0, L A is R 3 or R 4 or the oxygen atom of -OH in EUB. A Or office worker A where, if the amine is a tertiary amine, the nitrogen atom of the amine is L A combines with to form a quaternary ammonium The antibody-drug conjugate or salt thereof according to (43-2), wherein m is a number of 2 to 10. (43-15) A is N, R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3 is alkyl, R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): Z is a group represented by the following formula (XVIII): Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, R PEG is -C(=O)-(CH2CH2O) b -CH3, and b is an integer from 2 to 20; CLL is a partial structure that can be cleaved in vivo and is represented by formula (CL-2), *STR indicates the binding site with Str, t is 0, L A is a linker for binding Ab to D, and D has a group R 4 N(R 4a )2 bonded to the nitrogen atom -N + (R 4a )2-L A The antibody-drug conjugate or salt thereof according to (43-14), which forms (43-16) A is N, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 is alkyl, R 4a is C 1-3 is alkyl, Y is phenylene; L P is a bond, EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 is alkyl, R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): The antibody-drug conjugate or salt thereof according to (43-2), wherein Z is a group represented by the following formula (XVIII): (43-17) A is CR A , or N, R A is H, X 1 is -O-, R 1 is a group represented by the following formula (III-a): R2 is cyclopropyl, R 3 is a group selected from the group consisting of the following formula (IV-a) and formula (Va): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H, R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, R 3f is H, R N1 and R N2 are the same or different and are H or C 1-3 is alkyl, X 2 is —O— or —NH—, X 3 is O, p is 1, R 4 C may be substituted with OCH3 1-6 is alkyl, Y is phenylene; L P is a bond, EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl, R 6a is H and R 6b is hydroxymethyl, R 7 is a group selected from the group consisting of the following formula (XIX-a) and formula (XVI), W is a group represented by formula (XVII-a), Z is a group represented by the following formula (XVIII-a), or a salt thereof according to (43-2). (In the formula, * L P ) indicates the connection point with . (43-18)L A is a linker represented by formula (XV) *Ab indicates the binding site with Ab), Str is a stretcher unit that binds to Ab and CLL, r is 0, CLL is a partial structure that can be cleaved in vivo and is represented by the formula (CL-3). (In the formula, *STR indicates the binding site with Str), Sp is a spacer unit represented by formula (SP-4) (In the formula, *CLL indicates the binding site to CLL. ), binds to CLL and D, t is 1, L A is bonded to the oxygen atom of -OH contained in the group EUB that D has, and A The antibody-drug conjugate or salt thereof according to (43-2), which forms (43-19) The antibody-drug conjugate or a salt thereof according to any one of (43-1) to (43-18), wherein D is a heterocyclic compound having a mutant KRAS protein degradation-inducing activity represented by formula (PL-1′): *LA L A (represents the bond with (43-20)L A The antibody-drug conjugate or salt thereof according to any one of (43-1) to (43-19), wherein the antibody-drug conjugate or salt thereof is represented by the following formula (LA-3): *Ab indicates the Ab binding site). (43-21) L A The antibody-drug conjugate or salt thereof according to any one of (43-1) to (43-19), wherein the antibody-drug conjugate or salt thereof is represented by the following formula (LA-4): *Ab indicates the Ab binding site). (43-22) L A The antibody-drug conjugate or salt thereof according to any one of (43-1) to (43-19), wherein: *Ab indicates the Ab binding site). (43-23) The antibody-drug conjugate or a salt thereof according to (43-2), which is represented by the following formula (AD-1), (AD-2) or (AD-3): (wherein b is an integer from 2 to 20, and m is a number from 2 to 10). (43-24) The antibody-drug conjugate or a salt thereof according to (43-2), which is represented by the following formula (AD-1): (wherein b is an integer from 2 to 20, and m is a number from 2 to 10). (43-25) The antibody-drug conjugate or a salt thereof according to (43-2), which is represented by the following formula (AD-2): (wherein b is an integer from 2 to 20, and m is a number from 2 to 10). (43-26) The antibody-drug conjugate according to (43-2) or a salt thereof, which is represented by the following formula (AD-3): (where m is a number between 2 and 10). (43-27) Ab is 5T4, ADAM9, ALPP, ALPPL2, AXL, B7H3, B7H4, BCMA, CA9, CCR2, CCR7, CD123, CD166, CD19, CD20, CD22, CD25, CD30, CD33, CD37, CD38, CD45, CD46, CD70, CD74, CD79b, CDH3, CDH6, CEACAM5, CEACAM6, CLDN1, CLDN4, CLDN6, CLDN18.2, cMET, EGFR, EphA3, FAP, FGFR3, Fibronectin, FOLRa, Globo H, GPRC5D, HER2, HER3, IGF1R, Integrin The antibody-drug conjugate or salt thereof according to any one of (43-1) to (43-26), which is an antibody or antigen-binding fragment that binds to an antigen selected from the group consisting of αV, KAAG1, LIV1, MSLN, MT1-MMP, MUC1, MUC4, NaPi2b, Nectin-4, PD-L1, PSMA, PTK7, ROR1, ROR2, SEZ6, SialylTn, TF, TROP2, TSPAN8, and VEGF. (43-28) The antibody-drug conjugate or salt thereof according to any one of (43-1) to (43-26), wherein Ab is an antibody or antigen-binding fragment that binds to an antigen selected from the group consisting of EGFR, HER2, Nectin-4, and TROP2. (43-29) The antibody-drug conjugate or a salt thereof according to any one of (43-1) to (43-26), wherein Ab is an anti-EGFR antibody or an antigen-binding fragment thereof. (43-30) The antibody-drug conjugate or salt thereof according to (43-29), wherein Ab is an anti-EGFR antibody or an antigen-binding fragment thereof comprising the heavy chain variable region and the light chain variable region described in the following (1) or (2): (1) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 31 to 35 of SEQ ID NO: 1, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 65 of SEQ ID NO: 1, and CDR3 consisting of the amino acid sequence from amino acid numbers 98 to 108 of SEQ ID NO: 1; and a light chain variable region comprising a CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 2, a CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 2, and a CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 2; or (2) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 3, CDR2 consisting of the amino acid sequence of amino acids 50 to 65 of SEQ ID NO: 3, and CDR3 consisting of the amino acid sequence of amino acids 98 to 108 of SEQ ID NO: 3; and A light chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 4, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 4. (43-31) The antibody-drug conjugate or salt thereof according to (43-30), wherein Ab is an anti-EGFR antibody or an antigen-binding fragment thereof comprising a heavy chain variable region and a light chain variable region selected from the group consisting of the following (1) to (3): (1) a heavy chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 119 of SEQ ID NO: 1 and a light chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 107 of SEQ ID NO: 2; (2) a heavy chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 119 of SEQ ID NO: 3 and a light chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 107 of SEQ ID NO: 4; and (3) A heavy chain variable region and a light chain variable region having at least 90% identity to the heavy chain variable region and the light chain variable region described in (1) or (2) above. (43-32) The antibody-drug conjugate or a salt thereof according to (43-31), wherein Ab is an IgG1 or IgG4 anti-EGFR antibody. (43-33) The antibody-drug conjugate or a salt thereof according to (43-32), wherein Ab is cetuximab or a modified form thereof. (43-34) The antibody-drug conjugate or a salt thereof according to (43-32), wherein Ab is cetuximab. (43-35) The antibody-drug conjugate or a salt thereof according to (43-32), wherein Ab is an anti-EGFR antibody consisting of a heavy chain of SEQ ID NO: 1 and a light chain of SEQ ID NO: 2. (43-36) The antibody-drug conjugate or salt thereof according to any one of (43-14) to (43-35), wherein Ab is an antibody or antigen-binding fragment thereof that has been post-translationally modified, or in which any amino acid residue has been substituted with cysteine or a non-natural amino acid. (43-37) The antibody-drug conjugate or a salt thereof according to any one of (43-1) to (43-36), wherein b is an integer of 5 to 15. (43-38) The antibody-drug conjugate or salt thereof according to any one of (43-1) to (43-36), wherein b is an integer of 10 to 12. (43-39) The antibody-drug conjugate or a salt thereof according to any one of (43-1) to (43-36), wherein b is 12. (43-40) The antibody-drug conjugate or salt thereof according to any one of (43-1) to (43-39), wherein m is a number of 2 to 10. (43-41) The antibody-drug conjugate or a salt thereof according to any one of (43-1) to (43-39), wherein m is a number of 3 to 9. (43-42) The antibody-drug conjugate or a salt thereof according to any one of (43-1) to (43-39), wherein m is a number of 2 to 6. (43-43) The antibody-drug conjugate or a salt thereof according to any one of (43-1) to (43-39), wherein m is a number of 3 to 5. (43-44) The antibody-drug conjugate or a salt thereof according to any one of (43-1) to (43-39), wherein m is a number of 6 to 10. (43-45) The antibody-drug conjugate or a salt thereof according to any one of (43-1) to (43-39), wherein m is a number of 7 to 9. (43-46) An antibody-drug conjugate represented by formula (I) or a salt thereof (In the formula, The Ab is an anti-EGFR antibody or an antigen-binding fragment thereof comprising a heavy chain variable region and a light chain variable region described in (1) or (2) below: (1) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 31 to 35 of SEQ ID NO: 1, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 65 of SEQ ID NO: 1, and CDR3 consisting of the amino acid sequence from amino acid numbers 98 to 108 of SEQ ID NO: 1; and a light chain variable region comprising a CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 2, a CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 2, and a CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 2; or (2) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence of amino acids 31 to 35 of SEQ ID NO: 3, CDR2 consisting of the amino acid sequence of amino acids 50 to 65 of SEQ ID NO: 3, and CDR3 consisting of the amino acid sequence of amino acids 98 to 108 of SEQ ID NO: 3; and a light chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 4, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 4; L A is a linker represented by formula (LA-3) ( *Ab indicates the binding site with Ab), b is 12, D is a heterocyclic compound having an activity of inducing the degradation of mutant KRAS protein, represented by formula (PL-1') (wherein: *LA is L A (representing the bond with m is a number between 3 and 9). The antibody-drug conjugate of formula (I) or a salt thereof may exist in the form of a tautomer or a geometric isomer depending on the type of substituent. Although the compound of formula (I) may be described herein in only one isomeric form, the present invention also encompasses other isomers, and also encompasses isolated isomers or mixtures thereof. Furthermore, the antibody-drug conjugate of formula (I) or a salt thereof may have an asymmetric carbon atom or an asymmetric axis, and diastereomers based on this may exist. The present invention also encompasses separated diastereomers of the antibody-drug conjugate of formula (I) or a salt thereof, or a mixture thereof. Furthermore, the antibody-drug conjugate of formula (I) or a salt thereof is a pharmaceutically acceptable salt of the antibody-drug conjugate of formula (I) or a salt thereof, which may form an acid addition salt or a salt with a base depending on the type of substituent. Examples include salts described in P. Heinrich Stahl, Handbook of Pharmaceutical Salts Properties, Selection, and Use, Wiley-VCH, 2008. Specific examples include acid addition salts with inorganic acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, nitric acid, and phosphoric acid; and organic acids such as formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, succinic acid, fumaric acid, maleic acid, lactic acid, malic acid, mandelic acid, tartaric acid, dibenzoyltartaric acid, ditoluoyltartaric acid, citric acid, methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, aspartic acid, and glutamic acid; salts with inorganic metals such as sodium, potassium, magnesium, calcium, and aluminum; salts with organic bases such as methylamine, ethylamine, and ethanolamine; salts with various amino acids and amino acid derivatives such as acetylleucine, lysine, and ornithine; and ammonium salts. Furthermore, the present invention also encompasses various hydrates and solvates, and crystalline polymorphic substances of the antibody-drug conjugate of formula (I) or a salt thereof. The present invention also encompasses all antibody-drug conjugates of formula (I) or salts thereof that are labeled with one or more pharmaceutically acceptable radioactive or non-radioactive isotopes. Examples of suitable isotopes for use in isotopic labeling of the compounds of the present invention include hydrogen ( 2 H and 3 H, etc.), carbon ( 11 C. 13 C and 14 C, etc.), nitrogen ( 13 N and 15 N, etc.), oxygen ( 15 O, 17 O and18 O etc.), fluorine ( 18 F, etc.), chlorine ( 36 Cl, etc.), iodine ( 123 I and 125 I, etc.), sulfur ( 35 Isotopes of sulphur (e.g., sulphur) are included. It can be used for research such as tissue distribution studies of the compounds, drugs and / or substrates of the present invention labeled with isotopes. For example, tritium ( 3 H), carbon-14 ( 14 Radioisotopes such as C) may be used for this purpose because of their ease of labeling and convenience of detection. Substitution of heavier isotopes, e.g., deuterium for hydrogen ( 2 H) may be therapeutically advantageous due to increased metabolic stability (e.g., increased in vivo half-life, reduced dosage requirements, and reduced drug interactions). Positron-emitting isotopes ( 11 C, 18 F, 15 O and 13 Substitutions with 2-amino-1-methyl-2-(N, etc.) may be used in positron emission tomography (PET) studies to examine substrate receptor occupancy. The isotopically labeled compounds of the present invention can generally be produced by conventional methods known to those skilled in the art, or by a process similar to that described in the Examples or Preparations, using an appropriate isotopically labeled reagent instead of an unlabeled reagent. (Manufacturing method) The antibody-drug conjugate of formula (I) or a salt thereof can be produced by various known synthetic methods, taking advantage of characteristics based on its basic structure or the type of substituent. In this case, depending on the type of functional group, it may be effective from a manufacturing technology perspective to replace the functional group with an appropriate protecting group (a group that can be easily converted to the functional group) at the stage from the raw material to the intermediate. Examples of such protecting groups include those described in "Greene's Protective Groups in Organic Synthesis," 5th Edition, by P.G.M. Wuts and T.W. Greene, John Wiley & Sons Inc., 2014, and the like, which may be appropriately selected and used depending on the reaction conditions. In such methods, the desired compound can be obtained by introducing the protecting group, carrying out the reaction, and then removing the protecting group as necessary. Hereinafter, the antibody-drug conjugate of formula (I) or a salt thereof, and the drug (D) and drug-linker conjugate (L) that constitute the antibody-drug conjugate or a salt thereof will be described. A Representative methods for producing antibodies (Abs) and antibodies (D) are described below. Each method can also be performed by referring to the references provided in the description. However, the production methods of the present invention are not limited to the examples shown below. In this specification, the following abbreviations may be used. DMF: N,N-dimethylformamide, DMA: N,N-dimethylacetamide, NMP: N-methyl-2-pyrrolidone, THF: tetrahydrofuran, MeCN: acetonitrile, MeOH: methanol, EtOH: ethanol, iPrOH: isopropyl alcohol, tBuOH: tert-butyl alcohol, DOX: 1,4-dioxane, DMSO: dimethyl sulfoxide, iPr2O: diisopropyl ether, TEA: triethylamine, DIPEA: N,N-diisopropylethylamine, NMM: N-methylmorpholine, DMEDA: N,N'-dimethylethylenediamine, DBU: 1,8-diazabicyclo[5.4.0]-7-undecene, DABCO: 1,4-diazabicyclo[2.2.2]octane, Triton B: benzyltrimethylammonium hydroxide, tBuOK: potassium tert-butoxide, LHMDS: lithium bis(trimethylsilyl)amide, NHMDS: sodium bis(trimethylsilyl)amide, PdCl2(dppf)·CH2Cl2: [1,1'-bis(diphenylphosphino)ferrocene]palladium(II) dichloride·dichloromethane adduct, Pd / C: palladium on carbon, SPhos Pd G3: (2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl) [2-(2'-amino-1,1'-biphenyl)]palladium(II) methanesulfonate, SPhos: 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl, Xantphos: 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, RuPhos: 2-dicyclohexylphosphino-2',6'-diisopropoxybiphenyl, XPhos: 2-dicyclohexylphosphino-2',4',6'-triisopropylbiphenyl, BINAP: 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, PyBOP: (benzotriazol-1-yloxy)tripyrrolidinophosphonium Hexafluorophosphate, PyAOP: (7-azabenzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate, HATU: 1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo[4,5-b]pyridinium 3-oxide hexafluorophosphate, COMU: N-[({[(1Z)-1-cyano-2-ethoxy-2-oxoethylidene]amino}oxy)(morpholin-4-yl)methylene]-N-methylmethanaminium Hexafluorophosphate, CDI: 1,1'-carbonyldiimidazole, TFA: trifluoroacetic acid, TfOH: trifluoromethanesulfonic acid, NMO: N-methylmorpholine N-oxide, TBAF: tetrabutylammonium fluoride, TCEP: tris(2-carboxyethyl)phosphine, TSTU: N,N,N'N'-tetramethyl-O-(N-succinimidyl)uronium tetrafluoroborate, TBTA: tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine, TMAD: N,N,N',N'-tetramethylazodicarboxamide, EDTA: ethylenediaminetetraacetic acid, NBS: N-bromosuccinimide, DMAP: 4-dimethylaminopyridine, TBSOTf: tert-butyldimethylsilyl trifluoromethanesulfonate, ADMP: 2-azido-1,3-dimethylimidazolinium Hexafluorophosphate, Me: methyl, TBS: tert-butyldimethylsilyl, FMOC: 9-fluorenylmethyloxycarbonyl, Ac: acetyl, PPTS: pyridinium p-toluenesulfonate, BOC: tert-butoxycarbonyl. I. Method for manufacturing drug (D) (Drug manufacturing method 1) (In the formula, R 1A , R 3A is R 1 , R 3 PG represents a divalent group in which a hydrogen atom has been eliminated from a functional group to which a protecting group can be introduced. 1 , P.G. 2 indicates a protecting group. In some cases, one of the protecting groups may be absent. The same applies below.) This method is a method for producing a heterocyclic compound represented by formula (II). The heterocyclic compound of formula (II) can be obtained by subjecting compound (1) to a deprotection reaction. After the deprotection reaction, R 3Examples of protecting groups include tert-butoxycarbonyl, triphenylmethyl, tetrahydro-2H-pyran-2-yl, methoxymethyl, dimethylmethanediyl, and tert-butylsulfinyl. The deprotection reaction is typically carried out under cooling or reflux with stirring for 0.1 hours to 5 days. Examples of solvents used include, but are not limited to, alcohols such as MeOH, EtOH, and iPrOH; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform; ethers such as diethyl ether, THF, DOX, and dimethoxyethane; DMF, DMSO, MeCN, water, and mixtures thereof. Examples of deprotection reagents include, but are not limited to, hydrogen chloride (DOX solution), trifluoroacetic acid, methanesulfonic acid, p-toluenesulfonic acid, phosphoric acid, and other acids. By selecting a protecting group, deprotection can also be carried out by catalytic hydrogenation. Examples of protecting groups include benzyl, p-methoxybenzyl, and benzyloxycarbonyl groups. Deprotection can also be carried out using a fluoride ion source such as tetra-n-butylammonium fluoride. Examples of protecting groups include tert-butyl(dimethyl)silyl and (trimethylsilyl)ethoxymethyl groups. Furthermore, examples of protecting groups that can be deprotected under basic conditions include acetyl, trifluoroacetyl, and benzoyl groups. PG 1 , P.G. 2 Alternatively, protecting groups that can be deprotected under different deprotection conditions may be selected and deprotection may be carried out stepwise. The alkylation reaction uses formaldehyde or an alkyl group bearing a formyl group and is carried out in the presence of a reducing agent in a reaction-inert solvent, typically stirring at temperatures between -45°C and reflux, preferably between 0°C and room temperature, for 0.1 hours to 5 days. Examples of solvents that can be used include, but are not limited to, alcohols such as methanol and ethanol, ethers such as diethyl ether, tetrahydrofuran (THF), dioxane, and dimethoxyethane, halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform, and mixtures thereof. Reducing agents include sodium cyanoborohydride, sodium triacetoxyborohydride, and sodium borohydride. It may be preferable to carry out the reaction in the presence of a dehydrating agent such as molecular sieves or an acid such as acetic acid, hydrochloric acid, or titanium(IV) isopropoxide complex. For reference, the following can be referred to, for example: PGM Wuts and TW Greene, "Greene's Protective Groups in Organic Synthesis," 5th ed., John Wiley & Sons Inc., 2014 A.R. Katritzky and R.J.K. Taylor, Comprehensive Organic Functional Group Transformations II, Vol. 2, Elsevier Pergamon, 2005 When the starting compound (1) has axial chirality, the compound (1) may be separated and the resulting stereoisomer may be used in this reaction. The heterocyclic compound of formula (II) can be subjected to a salt-forming reaction, for example, by the following procedure, to obtain the hydrochloride of the heterocyclic compound of formula (II). The heterocyclic compound of formula (II), which is believed to form a salt with hydrochloric acid based on its chemical structure, is dissolved in CHCl and MeOH, and hydrogen chloride (4 M DOX solution, 10 equivalents) is added under ice-cooling. The mixture is stirred for 30 minutes under ice-cooling. The reaction mixture is concentrated under reduced pressure, and diethyl ether is added to the resulting residue. The resulting solid is filtered and dried under reduced pressure to obtain the hydrochloride salt of the heterocyclic compound of formula (II). The hydrochloride salt of the heterocyclic compound of formula (II) can be desalted by, for example, the following procedure to obtain the heterocyclic compound of formula (II), but the method is not limited to this. The hydrochloride salt of the heterocyclic compound of formula (II) is purified by ODS column chromatography (MeCN / 0.1% formic acid aqueous solution). The fractions containing the target product are pooled and basified with saturated aqueous sodium bicarbonate, followed by extraction with CHCl3 / MeOH (5 / 1). The combined organic layers are dried over anhydrous sodium sulfate, and the solution is concentrated under reduced pressure to obtain a solid. The solid is washed with diethyl ether and dried under reduced pressure to obtain the heterocyclic compound of formula (II). (Drug manufacturing method 2) This method is a method for producing a heterocyclic compound represented by formula (II-b), which is one of the heterocyclic compounds represented by formula (II). The heterocyclic compound represented by formula (II-b) can be obtained by the cycloaddition reaction of compound (2) and compound (3). This reaction involves using equal amounts of compound (2) and compound (3), or an excess of either. The mixture is stirred, preferably in the presence of a copper salt, more preferably in the presence of a copper salt and a reducing agent, in a reaction-inert solvent or without a solvent, under cooling to reflux, preferably at temperatures between 0°C and 100°C, typically for 0.1 hours to 5 days. Examples of solvents that can be used include, but are not limited to, halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform; aromatic hydrocarbons such as benzene, toluene, and xylene; ethers such as diethyl ether, THF, DOX, and 1,2-dimethoxyethane; DMF, DMSO, ethyl acetate, MeCN, tBuOH, water, and mixtures thereof. Examples of copper salts include CuI, CuSO4, and copper(I) trifluoromethanesulfonate (CuOTf). Examples of reducing agents include sodium ascorbate. In some cases, it is advantageous to carry out the reaction in the presence of TEA, DIPEA, NMM, 2,6-lutidine, TBTA, or the like in order to ensure smooth progress of the reaction. [Literature] Angew. Chem. Int. Ed. 2002, 41, p.2596-2599. (Drug raw material synthesis 1) This production method is the first method for producing compound (1)-1, which is included in starting compound (1). (First step) This step involves R 3 , R 4 This method produces compound (1)-1 by cycloaddition of compound (2)-1, which is protected with a protecting group, with compound (3). The reaction conditions are the same as those for the cycloaddition reaction in Drug Production Method 2. In addition, the PG of compound (2)-1 2 Alternatively, the compound obtained by first subjecting the compound to a deprotection reaction may be used to carry out this reaction. (Drug raw material synthesis 2) (where R is C 1-3 (This indicates an alkyl group. The same applies below.) This production method is the second method for producing compound (1)-1, which is included in starting compound (1). (First step) This step is a method for producing compound (5) by cycloaddition reaction of compound (2)-1 with compound (4). The reaction conditions were the same as those in the first step of Drug Substance Synthesis 1. (Second process) This step is a method for producing compound (6) by hydrolyzing compound (5). This reaction is carried out by stirring compound (5) under cooling or reflux, usually for 0.1 hours to 5 days. Examples of solvents used here include, but are not limited to, alcohols, acetone, DMF, THF, etc. Mixing the above solvents with water may also be suitable for the reaction. Examples of hydrolysis reagents include, but are not limited to, aqueous sodium hydroxide, aqueous potassium hydroxide, trimethyltin hydroxide, etc. As references for this reaction, for example, the following can be referred to. "Experimental Chemistry Lectures (5th Edition)" edited by the Chemical Society of Japan, Vol. 16 (2005) (Maruzen) Angew. Chem. Int. Ed. 2005, 44, p.1378-1382. (Third step) This step is a method for producing compound (1)-1 by an amidation reaction between compound (6) and compound (7). This reaction involves using equal amounts of compound (6) and compound (7), or an excess of either, and stirring the mixture in the presence of a condensing agent in a reaction-inert solvent under cooling to heating, preferably at temperatures between -20°C and 60°C, typically for 0.1 hours to 5 days. Examples of solvents include, but are not limited to, aromatic hydrocarbons such as toluene, ethers such as THF and DOX, halogenated hydrocarbons such as dichloromethane, alcohols, DMF, DMSO, ethyl acetate, MeCN, and mixtures thereof. Examples of condensing agents include PyBOP, HATU, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide or its hydrochloride, N,N'-dicyclohexylcarbodiimide (DCC), CDI, diphenylphosphoryl azide (DPPA), etc. The use of an additive (e.g., 1-hydroxybenzotriazole) may be beneficial in some cases. In some cases, it is advantageous to carry out the reaction in the presence of an organic base such as TEA, DIPEA, or NMM, or an inorganic base such as potassium carbonate, sodium carbonate, or potassium hydroxide, in order to ensure that the reaction proceeds smoothly. Alternatively, compound (6) can be converted into a reactive derivative and then acylated. Examples of reactive derivatives of carboxylic acids include acid halides obtained by reaction with a halogenating agent such as phosphorus oxychloride or thionyl chloride, mixed acid anhydrides obtained by reaction with isobutyl chloroformate, and activated esters obtained by condensation with 1-hydroxybenzotriazole. The reaction of these reactive derivatives with compound (7) can be carried out in a reaction-inert solvent such as halogenated hydrocarbons, aromatic hydrocarbons, or ethers, under cooling or heating, preferably at -20°C to 120°C. [Literature] S.R. Sandler and W. Karo, "Organic Functional Group Preparations," 2nd ed., Vol. 1, Academic Press Inc., 1991 "Experimental Chemistry Lectures (5th Edition)" edited by the Chemical Society of Japan, Vol. 16 (2005) (Maruzen) (Drug raw material synthesis 3) (In the formula, R 3B is NR3aa R 3bb , OR 3cc , R 3dd indicates PG 1A , P.G. 3 indicates a protecting group. 3B is NR 3a R 3b , OR 3c , R 3d R represents a divalent group in which a hydrogen atom (H) has been eliminated from a functional group to which a protecting group can be introduced, and a functional group to which a carbonyl group or a carboxyl group can be introduced. 1 is PG 2 (The same applies below.) This production method is the second method for producing compound (1)-2 contained in starting compound (1). (First step) This step is a method for producing compound (9) by cycloaddition reaction of compound (8) with compound (3). The reaction conditions were the same as those in the first step of Drug Substance Synthesis 1. (Second process) This step is a method for producing compound (10) by subjecting compound (9) to a deprotection reaction. The reaction conditions are the same as those for the deprotection reaction in Drug Production Method 1. (Third step) This step is a method for producing compound (1)-2 by reacting compound (10) with a carbonylation reagent and then adding compound (11), or a method for producing compound (1)-2 by an amidation reaction of compound (10) with compound (12). This step is carried out by reacting compound (10) with an equivalent or excess amount of a carbonylation reagent in a reaction-inert solvent under cooling to heating, preferably at −20°C to 80°C, typically for 0.1 hour to 1 day. Subsequently, an equivalent or excess amount of compound (11) is added to the resulting reaction mixture, and the mixture is reacted under cooling to heating, preferably at −20°C to 80°C, for 0.1 hour to 1 day. Examples of carbonylation reagents include 1,1'-carbonyldiimidazole, 4-nitrophenyl chloroformate, diphosgene, triphosgene, and phenyl chloroformate. Examples of solvents used herein include, but are not limited to, halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform; aromatic hydrocarbons such as benzene, toluene, and xylene; ethers such as diethyl ether, tetrahydrofuran, dioxane, and dimethoxyethane; N,N-dimethylformamide; dimethyl sulfoxide; ethyl acetate; acetonitrile; and mixtures thereof. In some cases, it may be advantageous to carry out the reaction in the presence of a base such as triethylamine in order to ensure smooth progress of the reaction. The reaction conditions for the amidation reaction of compound (10) and compound (12) are the same as those for the third step of Starting Material Synthesis 2. [Literature] S.R. Sandler and W. Karo, "Organic Functional Group Preparations," 2nd ed., Vol. 2, Academic Press Inc., 1991 (Drug Raw Material Synthesis 4) (In the formula, PG 4 , P.G. 5 indicates a protecting group. LG is C 1-12 Alkyl group, LG 1represents a leaving group, and BLG represents a boronic acid group, a boronic acid group protected by a boronic acid protecting group such as a boronic acid pinacol ester group, or a trifluoroborate group (hereinafter, sometimes referred to as a boronic acid group, etc.). Examples of the leaving group shown here include Cl, Br, a methanesulfonyloxy group, a p-toluenesulfonyloxy group, etc. This production method is a method for producing compound (2)-2 contained in raw material compound (2)-1. (First step) This step is a method for producing compound (14) by hydrolyzing compound (13). This reaction is carried out by stirring compound (13) under cooling or reflux, usually for 0.1 hours to 5 days. Examples of solvents used here include, but are not limited to, alcohols, acetone, DMF, THF, etc. Mixing the above solvents with water may also be suitable for the reaction. Examples of hydrolysis reagents include, but are not limited to, aqueous sodium hydroxide, aqueous potassium hydroxide, etc. As references for this reaction, for example, the following can be referred to. "Experimental Chemistry Lectures (5th Edition)" edited by the Chemical Society of Japan, Vol. 16 (2005) (Maruzen) Angew. Chem. Int. Ed. 2005, 44, p.1378-1382. (Second process) This step is a method for producing compound (15) by protecting the hydroxyl group of compound (14) with a protecting group. For example, when protecting with a tert-butyl group, this reaction is carried out by stirring compound (14) under cooling or reflux, usually for 0.1 hours to 5 days. Examples of solvents used here include, but are not limited to, ethers such as THF and DOX, halogenated hydrocarbons such as dichloromethane, tBuOH, DMF, etc. Examples of tert-butyl protecting reagents include, but are not limited to, isobutene, 2-tert-butyl-1,3-diisopropylisourea, etc. Alternatively, compound (15) can be produced by a dehydration condensation reaction of compound (14) with tBuOH. As references for this reaction, for example, the following can be referred to. PGM Wuts and TW Greene, "Greene's Protective Groups in Organic Synthesis," 5th ed., John Wiley & Sons Inc., 2014 Org. Lett., 2012, 14, 17, p.4678-4681 (Third step) This step involves the reaction of compound (15) with R LG This method involves the production of compound (16) by ipso substitution reaction with -SH. The R used here LG An example of -SH is C 1-12 Alkyl thiols, such as ethanethiol and dodecanethiol, are examples of the reaction. LG The mixture is stirred in a reaction-inert solvent, or without solvent, under cooling to reflux, preferably at 0°C to 80°C, for typically 0.1 hours to 5 days. Examples of solvents that can be used include, but are not limited to, halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform; aromatic hydrocarbons such as benzene, toluene, and xylene; ethers such as diethyl ether, THF, DOX, and 1,2-dimethoxyethane; DMF, DMA, DMSO, ethyl acetate, MeCN, and mixtures thereof. Carrying out the reaction in the presence of an organic base such as TEA, DIPEA, NMM, DABCO, or tBuOK, or an inorganic base such as sodium hydride, potassium carbonate, sodium carbonate, or cesium carbonate, may be advantageous for smooth reaction progress. (Fourth step) This process involves the reaction of compound (16) with PG 5 This method produces compound (17) by ipso substitution reaction with -OH. 5Examples of -OH include, but are not limited to, benzyl alcohol, p-methoxybenzyl alcohol, 1-phenylethanol, 1-(naphthalen-1-yl)ethan-1-ol, (1S)-1-(naphthalen-1-yl)ethan-1-ol, and (1R)-1-(naphthalen-1-yl)ethan-1-ol. The reaction conditions were the same as those in the third step of Drug Substance Synthesis 4. (Fifth step) This step involves the reaction of compound (17) with R 2 This is a method for producing compound (18) by Suzuki-Miyaura coupling reaction with a boronic acid derivative comprising a -boronic acid group or the like. Examples of the boronic acid group used herein include, but are not limited to, a boronic acid group, a boronic acid ester group, a boronic acid pinacol ester group, a triol borate base, and a trifluoroborate base. This reaction is carried out by reacting compound (17) with R 2A mixture of these compounds is stirred in the presence of a base and a palladium catalyst in a reaction-inert solvent at room temperature to reflux, preferably at 20°C to 140°C, for typically 0.1 hours to 5 days. Examples of solvents that can be used include, but are not limited to, halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform; aromatic hydrocarbons such as benzene, toluene, and xylene; ethers such as diethyl ether, THF, DOX, and 1,2-dimethoxyethane; alcohols such as MeOH, EtOH, isopropyl alcohol, butanol, and amyl alcohol; DMF, DMSO, MeCN, 1,3-dimethylimidazolidin-2-one; water; and mixtures thereof. Examples of bases include inorganic bases such as tripotassium phosphate, sodium carbonate, potassium carbonate, sodium hydroxide, and barium hydroxide. Palladium catalysts include tetrakis(triphenylphosphine)palladium, bis(triphenylphosphine)palladium(II) dichloride, PdCl2(dppf)·CHCl2, (1E,4E)-1,5-diphenylpenta-1,4-dien-3-one / palladium (3:2), SPhos Pd G3, (2-dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl)[2-(2'-amino-1,1'-biphenyl)]palladium(II) methanesulfonate, and palladium(II) acetate. The presence of ligands such as SPhos, RuPhos, and 1,1'-bis(diphenylphosphino)ferrocene can be advantageous for smooth reaction. Microwave heating of the mixture can also be beneficial for smooth reaction. [Literature] J. Am. Chem. Soc., 2005, 127, p.4685-4696 Org. Lett. 2011, 13, p.3948-3951 Org. Lett. 2012, 14, p.1278-1281 Compound (17) is dehalogenated using a Pd catalyst and a reducing agent to give compound (18) (where R2 can produce hydrogen). [Literature] J. Org. Chem., 1977, 42, p.3491-3494 Tetrahedron Letters 2013, 54, 5207-5210 (Sixth step) This step is a method for producing compound (20) by Suzuki-Miyaura coupling reaction between compound (18) and compound (19). The reaction conditions were the same as in the fifth step of Drug Substance Synthesis 4. When compound (20) has axial chirality, it is obtained as a mixture of stereoisomers. However, each stereoisomer can be isolated by a conventional resolution procedure, for example, resolution using ODS column chromatography or silica gel column chromatography. (Seventh step) This step is a method for producing compound (21) by oxidation of compound (20). In this reaction, compound (20) is treated with an equivalent or excess amount of an oxidizing agent in a reaction-inert solvent under cooling to heating, preferably at -20°C to 80°C, typically for 0.1 hours to 3 days. In this reaction, oxidation using m-chloroperbenzoic acid, perbenzoic acid, peracetic acid, sodium hypochlorite, or hydrogen peroxide is preferably used. Examples of solvents include aromatic hydrocarbons, ethers, halogenated hydrocarbons such as dichloromethane, DMF, DMSO, ethyl acetate, MeCN, water, and mixtures thereof. Examples of other oxidizing agents include cumene hydroperoxide, oxone, activated manganese dioxide, chromic acid, potassium permanganate, and sodium periodate. Carrying out the reaction in the presence of an inorganic base such as potassium carbonate, sodium carbonate, or sodium bicarbonate may be advantageous for smooth reaction progression. [Literature] Chemical Society of Japan, "Experimental Chemistry Lectures," 5th edition, Vol. 17, Maruzen, 2004 When compound (21) has axial chirality, it may be obtained as a mixture of stereoisomers. However, each stereoisomer can be isolated by a conventional resolution procedure, for example, resolution using ODS column chromatography or silica gel column chromatography. In addition, the protecting group PG 1 To enable deprotection under different conditions, compound (21) was subjected to the deprotection reaction and then deprotected under conditions different from those of PG. 2 may be converted to another protecting group. The reaction conditions for the deprotection reaction used here are the same as those in the step described in Production Method 1. PG to be subsequently converted 2 Examples of the protecting group include a tetrahydro-2H-pyran-2-yl group. As references for this reaction, for example, the following can be referred to. PGM Wuts and TW Greene, "Greene's Protective Groups in Organic Synthesis," 5th ed., John Wiley & Sons Inc., 2014 (Eighth process) This step is a method for producing compound (22) by deprotecting compound (21) through catalytic hydrogenation. This reaction can be carried out by stirring compound (21) under a hydrogen atmosphere at atmospheric to elevated pressure in a reaction-inert solvent such as MeOH, EtOH, ethyl acetate, THF, water, or a mixture thereof, in the presence of a metal catalyst, with cooling to heating, preferably at room temperature, for 1 hour to 5 days. Examples of the metal catalyst include palladium catalysts such as Pd / C and palladium black, platinum catalysts such as platinum plate and platinum oxide, and nickel catalysts such as reduced nickel and Raney nickel. Carrying out the reaction in the presence of an inorganic base such as potassium carbonate, sodium carbonate, or sodium bicarbonate can be advantageous in some cases for smooth reaction progression. (Ninth step) This step is a method for producing compound (24) by reacting compound (22) with compound (23). This reaction is carried out by reacting a mixture of equal amounts of compound (22) and compound (23), or an excess of either, in the presence of a base in a reaction-inert solvent under cooling to reflux, preferably at 0°C to 80°C, for typically 0.1 hours to 5 days. The solvent used here is not particularly limited, but includes aromatic hydrocarbons such as benzene, toluene, and xylene; alcohols such as MeOH and EtOH; ethers such as diethyl ether, THF, DOX, and 1,2-dimethoxyethane; halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform; DMF, DMSO, ethyl acetate, MeCN, and mixtures thereof. Examples of bases include, but are not limited to, organic bases such as TEA, DIPEA, DBU, n-butyllithium, and tBuOK; and inorganic bases such as sodium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate, and sodium hydride. It may be advantageous to carry out the reaction in the presence of a phase-transfer catalyst such as tetra-n-butylammonium chloride. As references for this reaction, for example, the following can be referred to. Chemical Society of Japan, "Experimental Chemistry Lectures," 5th edition, Vol. 14, Maruzen, 2005 Compound (24) is also a LG 1 By halogenating a compound in which the moiety corresponding to LG is a hydroxy group, 1 is a halogen. Examples of the halogenating agent used here include, but are not limited to, thionyl chloride, phosphorus oxychloride, hydrobromic acid, phosphorus tribromide, etc. As references for this reaction, for example, the following can be referred to. Chemical Society of Japan, "Experimental Chemistry Lectures," 5th edition, Vol. 13, Maruzen, 2004 Furthermore, compound (24) 1 The compound having a hydroxy group in the corresponding position is sulfonylated in the presence of a base to give LG 1is a sulfonyloxy group. Examples of the sulfonylation reagent used here include, but are not limited to, methanesulfonyl chloride, p-toluenesulfonyl chloride, methanesulfonic anhydride, etc. Examples of the base include, but are not limited to, TEA, DIPEA, pyridine, tetramethylethylenediamine, etc. As references for this reaction, for example, the following can be referred to. Synthesis 1999, 9, p.1633-1636 (10th step) This step is a method for producing compound (26) by ipso substitution reaction between compound (24) and compound (25). The reaction conditions were the same as those in the third step of Drug Substance Synthesis 4. (Eleventh step) This step is a method for producing compound (27) by subjecting compound (26) to a deprotection reaction. The reaction conditions are the same as those in the process described in Drug Production Method 1. (Twelfth step) This step is a method for producing compound (2)-2 by reacting compound (27) with compound (28). This reaction involves using equal amounts of compound (27) and compound (28) or an excess of one. A mixture of these is stirred in the presence of a condensing agent in a reaction-inert solvent under cooling to heating, preferably at temperatures between -20°C and 60°C, typically for 0.1 hours to 5 days. Examples of solvents include, but are not limited to, aromatic hydrocarbons such as toluene, ethers such as THF and DOX, halogenated hydrocarbons such as dichloromethane, alcohols, DMF, DMSO, ethyl acetate, MeCN, and mixtures thereof. Examples of condensing agents include PyAOP, PyBOP, HATU, and CDI. Carrying out the reaction in the presence of an organic base such as TEA, DIPEA, or NMM, or an inorganic base such as potassium carbonate, sodium carbonate, or cesium carbonate may be advantageous for smooth reaction progression. (Drug Raw Material Synthesis 4-2) This production method is a method for producing compound (2)-3 contained in starting compound (2). (First step) This step is a method for producing compound (102) by an ipso substitution reaction between compound (21) and compound (25). The reaction conditions were the same as those in the third step of Drug Substance Synthesis 4. (Second process) This step is a method for producing compound (103) by deprotecting compound (102) through catalytic hydrogenation. The reaction conditions were the same as in the eighth step of Drug Substance Synthesis 4. (Third step) This step is a method for producing compound (104) by reacting compound (103) with compound (23). The reaction conditions were the same as in Step 9 of Drug Substance Synthesis 4. (Fourth step) This step is a method for producing compound (105) by subjecting compound (104) to a deprotection reaction. The reaction conditions are the same as those for the deprotection reaction in Drug Production Method 1. (Fifth step) This step is a method for producing compound (2)-3 by reacting compound (105) with compound (106). The reaction conditions were the same as in the twelfth step of Drug Substance Synthesis 4. (Drug Raw Material Synthesis 5) This method is a method for producing the starting compound (26). (First step) This step is a method for producing compound (28) by the ipso substitution reaction between compound (15) and compound (25). The reaction conditions were the same as those in the third step of Drug Substance Synthesis 4. Furthermore, compound (28) can be produced by Negishi coupling of compound (15) with a compound obtained by converting the hydrogen atoms of compound (25) to halogens. (Second process) This process involves the reaction of compound (28) with PG 5This method involves the production of compound (29) by ipso substitution reaction with —OH. The reaction conditions were the same as those in the third step of Drug Substance Synthesis 4. (Third step) This step involves the reaction of compound (29) with R 2 This is a method for producing compound (30) by Suzuki-Miyaura coupling reaction with a boronic acid derivative comprising a -boronic acid group or the like. The reaction conditions were the same as in the fifth step of Drug Substance Synthesis 4. Compound (29) is dehalogenated using a Pd catalyst and a reducing agent to give compound (30) (where R 2 can produce hydrogen). [Literature] J. Org. Chem., 1977, 42, p.3491-3494 Tetrahedron Letters 2013, 54, 5207-5210 (Fourth step) This step is a method for producing compound (31) by Suzuki-Miyaura coupling reaction between compound (30) and compound (19). The reaction conditions were the same as in the fifth step of Drug Substance Synthesis 4. (Fifth step) This step is a method for producing compound (32) by deprotecting compound (31) through catalytic hydrogenation. The reaction conditions were the same as in the eighth step of Drug Substance Synthesis 4. (Sixth step) This step is a method for producing compound (26) by reacting compound (32) with compound (23). The reaction conditions were the same as in Step 9 of Drug Substance Synthesis 4. (Drug Raw Material Synthesis 6) This production method is a method for producing the starting compound (2)-2. (First step) This step is a method for producing compound (33) by subjecting compound (31) to a deprotection reaction. The reaction conditions are the same as those in the process described in Drug Production Method 1. When compound (31) has axial chirality, it may be obtained as a mixture of stereoisomers. However, each stereoisomer can be isolated by a conventional resolution procedure, for example, resolution using ODS column chromatography or silica gel column chromatography. In addition, the protecting group PG 1 To enable deprotection under different conditions, compound (31) was subjected to the deprotection reaction and then deprotected under conditions different from those of PG. 2 may be converted to another protecting group. (Second process) This step is a method for producing compound (34) by reacting compound (33) with compound (28). The reaction conditions were the same as in the twelfth step of Drug Substance Synthesis 4. (Third step) This step is a method for producing compound (35) by deprotecting compound (34) through catalytic hydrogenation. The reaction conditions were the same as in the eighth step of Drug Substance Synthesis 4. (Fourth step) This step is a method for producing compound (2)-2 by reacting compound (35) with compound (23). The reaction conditions were the same as in Step 9 of Drug Substance Synthesis 4. (Drug Raw Material Synthesis 7) This production method is a method for producing compound (8)-1, which is included in the starting compound (8). (First step) This step is a method for producing compound (37) by chlorination of compound (36). This reaction is carried out by using an equal amount of compound (36) and a chlorinating agent, or an excess amount of either, and stirring the mixture in a reaction-inert solvent or without a solvent under cooling to reflux, preferably at 60°C to reflux, for typically 0.1 hours to 5 days. Examples of solvents used here include, but are not limited to, aromatic hydrocarbons such as toluene, ethers such as THF and DOX, and halogenated hydrocarbons such as dichloromethane. Examples of chlorinating agents include phosphorus oxychloride and thionyl chloride. Carrying out the reaction in the presence of an organic base such as TEA, DIPEA, or NMM may be advantageous for smooth reaction progression. (Second process) This step involves the reaction of compound (37) with R LG This is a method for producing compound (3838) by an ipso substitution reaction with -SH. The reaction conditions were the same as those in the third step of Drug Substance Synthesis 4. (Third step) This process involves the reaction of compound (38) with PG 5 This method involves the production of compound (39) by ipso substitution reaction with —OH. The reaction conditions were the same as those in the third step of Drug Substance Synthesis 4. (Fourth step) This step is a method for producing compound (41) by ipso substitution reaction between compound (39) and compound (40). This reaction involves using equal amounts of compound (39) and compound (40), or an excess of either compound. The mixture is stirred in a reaction-inert solvent, or without solvent, under cooling to reflux, preferably at 0°C to 80°C, for typically 0.1 hours to 5 days. Examples of solvents that can be used include, but are not limited to, halogenated hydrocarbons such as dichloromethane, 1,2-dichloroethane, and chloroform; aromatic hydrocarbons such as benzene, toluene, and xylene; ethers such as diethyl ether, THF, DOX, and 1,2-dimethoxyethane; DMF, DMA, DMSO, ethyl acetate, MeCN, and mixtures thereof. It may be advantageous to carry out the reaction in the presence of an organic base such as TEA, DIPEA, NMM, DABCO, or tBuOK, or an inorganic base such as sodium hydride, potassium carbonate, sodium carbonate, or cesium carbonate, in order to ensure smooth reaction progress. (Fifth step) This step involves the reaction of compound (41) with R 2 This is a method for producing compound (42) by Suzuki-Miyaura coupling reaction with a boronic acid derivative comprising a -boronic acid group or the like. The reaction conditions were the same as in the fifth step of Drug Substance Synthesis 4. (Sixth step) This step is a method for producing compound (43) by Suzuki-Miyaura coupling reaction between compound (42) and compound (19). The reaction conditions were the same as in the fifth step of Drug Substance Synthesis 4. (Seventh step) This step is a method for producing compound (44) by oxidati...

Claims

1. An antibody-drug conjugate represented by formula (I) or a salt thereof (Wherein, Ab is an antibody or an antigen-binding fragment thereof, D is a heterocyclic compound having an activity of inducing mutant KRAS proteolysis, and L A is a linker for connecting Ab and D, and m is a number from 1 to 20).

2. D is a heterocyclic compound represented by formula (II) having the activity of inducing mutant KRAS protein degradation, A is CR A , or N and R A is H or C 1-3 is alkyl, and X 1 is -CH2- or -O-, R 1 represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R 1a is H, methyl, F or Cl, R 1b is F, Cl, methyl or ethyl, R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 alkyl, and R 3 is a group selected from the group consisting of the following formulas (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII), R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, and R 3b is H or C 1-3 alkyl, and R 3c and R 3d is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 cycloalkyl, where R 3c -(CH2) p CHR 3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 alkyl)-, and R 3e -OC 2-3 Alkylene-NR N1 R N2 and R 3f is H, F or C 1-3 alkyl, and R 3g is H or C 1-3 alkyl, and R 3h is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms, and R 3i are the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２ , halogen, —CN, and oxo, or two R present on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo, or R present on two adjacent carbon atoms. 3i together with the two carbon atoms to form C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo, or R present on two non-adjacent carbon atoms. 3i may form a bridged structure consisting of 1 to 2 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C 1-3 Alkyl, -O-(C 1-3 R is optionally substituted with 1 to 2 groups selected from the group consisting of alkyl, OH, halogen, and oxo; N1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2 may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 may form, together with the carbon atom and nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen, 2 is -O-, -NH-, or -N(C 1-3 alkyl)-, and X 3 is O or S, and X 4 is -CH2-, -CH2-CH2-, or -O-CH2-, n is 1 or 2, p is 1 or 2, q is an integer from 1 to 8, and R 4 are F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4a pyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4a C optionally substituted with F 1-3 alkyl, and R 4b is C substituted with 1 to 3 F 1-3 alkyl, Y is phenylene optionally substituted with F or Cl, or pyridinediyl, L P is a group that chemically bonds Y and EUB, EUB is a group that has the ability to bind to E3 ubiquitin ligase, and L A is a linker for binding Ab to D, and is bound to any nitrogen atom or oxygen atom of —OH contained in D. When the nitrogen atom is a tertiary amine, the nitrogen atom is bound to L A The antibody-drug conjugate or salt thereof according to claim 1 , which binds to the following to form a quaternary ammonium.

3. L A is a linker for binding Ab to D, and D has a group R 3 , R 4 or NL bonded to the nitrogen atom of the amine or the oxygen atom of -OH contained in EUB A Or office worker A where, if the amine is a tertiary amine, the nitrogen atom of the amine is L A The antibody-drug conjugate or salt thereof according to claim 2, which binds to the following to form a quaternary ammonium.

4. A is CR A , or N and R A is H and X 1 is -O- and R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, and R 3 is a group selected from the group consisting of the following formulas (IV), (V), and (XI): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H and R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, and R 3f is H and R N1 and R N2 are the same or different and are H or C 1-3 Alkyl and X 2 is -O- or -NH-, and X 3 is O, n is 1, p is 1, and R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 The antibody-drug conjugate or a salt thereof according to claim 3 , wherein Y is alkyl and Y is phenylene.

5. A is N and R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 alkyl, and R 4a is C 1-3 The antibody-drug conjugate or salt thereof according to claim 4, wherein the aryl group is alkyl.

6. The antibody-drug conjugate or salt thereof according to claim 3, wherein EUB is a group capable of binding to VHL.

7. EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is methyl, ethyl, isopropyl, isobutyl, sec-butyl, tert-butyl, C 3-6 cycloalkylmethyl, or C 3-6 is cycloalkyl, and R 6a and R 6b are the same or different and may be substituted with H or a group selected from the group consisting of OH, OCH3, and N(CH3)2; 1-6 alkyl, or R 6a , R 6b may be substituted together with the carbon to which they are attached. 3-6 may form a cycloalkane or an optionally substituted 4- to 6-membered saturated heterocyclic ring containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen as ring-constituting atoms, R 7 is an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or a 6-membered heteroaryl containing 1 to 3 nitrogen atoms; W is an optionally substituted phenylene or an optionally substituted 6-membered heteroarenediyl containing 1 to 3 nitrogen atoms as ring-constituting atoms; L P is -(L 1 -L 2 -L 3 -L 4 )- and L 1 , L 2 , L 3 , L 4 are the same or different and represent a bond, -O-, -NR L1 -, optionally substituted pyrrolidinediyl, optionally substituted piperidinediyl, optionally substituted piperazinediyl, optionally substituted C 1-3 is a group selected from the group consisting of alkylene and C═O, L1 is H or C 1-3 and Z is NH or a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, or a salt thereof.

8. EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 alkyl, and R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen; W is phenylene; L P The antibody-drug conjugate or a salt thereof according to claim 7, wherein: is a bond; and Z is a 5-membered heteroarenediyl containing, as ring-constituting atoms, 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen.

9. R 7 is a group selected from the group consisting of the following formulae (XIX-a), (XX-a), and (XVI), W is a group represented by the following formula (XVII-a):

9. The antibody-drug conjugate or salt thereof according to claim 8, wherein Z is a group represented by the following formula (XVIII):

10. R 7 The antibody-drug conjugate or a salt thereof according to claim 9 , wherein 11. L A is a linker represented by formula (XV): (Wherein, Str is a stretcher unit and binds to Ab and CLL, CLL is a partial structure that can be cleaved in vivo, Sp is a spacer unit and binds to CLL and D, t is 0 or 1, *Ab indicates the binding site with Ab.

12. i) Str is the stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 alkylene, -optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - or -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 alkylene-, a is an integer from 1 to 10, and R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, b is an integer of 2 to 20, CLL is a partial structure represented by formula (CL-1) that can be cleaved in vivo, *STR indicates the binding site with Str, R AA are each independently a group selected from the group consisting of H, methyl, isopropyl, benzyl, and —(CH2)3—NH—C(═O)—NH2, d is an integer from 2 to 4, Sp is a spacer unit represented by formula (SP-1), formula (SP-2), or formula (SP-3), and t is 1, *CLL indicates the binding site with CLL, R SP is H, or ii) Str is a Stretcher unit represented by formula (ST-1), and r is 1; *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, and R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, b is an integer of 2 to 20, CLL is a partial structure represented by formula (CL-2) that can be cleaved in vivo, *STR indicates the binding site with Str, The antibody-drug conjugate or salt thereof according to claim 11, wherein t is 0.

13. Str is the stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, and R PEG is -C(=O)-(CH2CH2O) b -CH3, b is an integer of 2 to 20, CLL is a partial structure represented by formula (CL-2) that can be cleaved in vivo, *STR indicates the binding site with Str, The antibody-drug conjugate or salt thereof according to claim 12, wherein t is 0.

14. A is CR A , or N and R A is H and X 1 is -O- and R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, and R 3 is a group selected from the group consisting of the following formulas (IV), (V), and (XI): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H and R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, and R 3f is H and R N1 and R N2 are the same or different and are H or C 1-3 Alkyl and X 2 is -O- or -NH-, and X 3 is O, n is 1, p is 1, and R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 Y is phenylene; EUB is a group capable of binding to VHL, said group capable of binding to VHL is a group represented by formula (XIV); R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 alkyl, and R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen; W is phenylene; L P is a bond, Z is a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, and L A is a linker represented by formula (XV) *Ab indicates the binding site with Ab), Str is a stretcher unit and binds to Ab and CLL, CLL is a partial structure that can be cleaved in vivo, Sp is a spacer unit and binds to CLL and D, and t is 0 or 1, wherein: i) Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 alkylene, -optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - or -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 alkylene-, a is an integer from 1 to 10, and R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, b is an integer of 2 to 20, CLL is a partial structure represented by formula (CL-1) that can be cleaved in vivo, *STR indicates the binding site with Str, R AA are each independently a group selected from the group consisting of H, methyl, isopropyl, benzyl, and —(CH2)3—NH—C(═O)—NH2, d is an integer from 2 to 4, Sp is a spacer unit represented by formula (SP-1), formula (SP-2), or formula (SP-3), and t is 1, *CLL indicates the binding site with CLL, R SP is H, or ii) Str is a Stretcher unit represented by formula (ST-1), and r is 1; *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, and R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, b is an integer of 2 to 20, CLL is a partial structure represented by formula (CL-2) that can be cleaved in vivo, *STR indicates the binding site with Str, t is 0 and L A is R 3 or R 4 or the oxygen atom of -OH in EUB. A Or office worker A where, if the amine is a tertiary amine, the nitrogen atom of the amine is L A and m is a number between 2 and 10.

15. A is N and R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 alkyl, and R 4a is C 1-3 alkyl, and R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): Z is a group represented by the following formula (XVIII): Str is a stretcher unit represented by formula (ST-1), r is 1, *Ab indicates the binding site with Ab, R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, and R PEG is -C(=O)-(CH2CH2O) b -CH3, b is an integer of 2 to 20, CLL is a partial structure represented by formula (CL-2) that can be cleaved in vivo, *STR indicates the binding site with Str, t is 0 and L A is R 4 N(R 4a )2 bonded to the nitrogen atom -N + (R 4a )2-L A The antibody-drug conjugate or salt thereof according to claim 14, wherein the compound forms:

16. The antibody-drug conjugate or salt thereof according to claim 3, which is represented by the following formula (AD-1), (AD-2), or (AD-3): (wherein b is an integer from 2 to 20, and m is a number from 2 to 10).

17. The antibody-drug conjugate or salt thereof according to claim 16, wherein b is 12 and m is a number from 3 to 9.

18. Ab, 5T4, ADAM9, ALPP, ALPPL2, AXL, B7H3, B7H4, BCMA, CA9, CCR2, CCR7, CD123, CD166, CD19, CD20, CD22, CD25, CD30, CD33, CD37, CD38, CD45, CD4 6, CD70, CD74, CD79b, CDH3, CDH6, CEACAM5, CEACAM6, CLDN1, CLDN4, CLDN6, CLDN18.2, cMET, EGFR, EphA3, FAP, FGFR3, Fibronectin, FOLRa, Globo H, GPRC5D, HER2, HER3, IGF1R, Integrin The antibody-drug conjugate or salt thereof according to claims 1 to 17, which is an antibody or antigen-binding fragment that binds to an antigen selected from the group consisting of αV, KAAG1, LIV1, MSLN, MT1-MMP, MUC1, MUC4, NaPi2b, Nectin-4, PD-L1, PSMA, PTK7, ROR1, ROR2, SEZ6, SialylTn, TF, TROP2, TSPAN8, or VEGF.

19. The antibody-drug conjugate or salt thereof according to any one of claims 1 to 17, wherein the Ab is an antibody or antigen-binding fragment that binds to an antigen selected from the group consisting of EGFR, HER2, Nectin-4, and TROP2.

20. The antibody-drug conjugate or salt thereof according to any one of claims 1 to 17, wherein Ab is an anti-EGFR antibody or an antigen-binding fragment thereof.

21. The antibody-drug conjugate or salt thereof according to claim 20, wherein the Ab is an anti-EGFR antibody or an antigen-binding fragment thereof comprising a heavy chain variable region and a light chain variable region according to (1) or (2) below: (1) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence from 31 to 35 of SEQ ID NO: 1, CDR2 consisting of the amino acid sequence from 50 to 65 of SEQ ID NO: 1, and CDR3 consisting of the amino acid sequence from 98 to 108 of SEQ ID NO: 1, and a light chain variable region comprising CDR1 consisting of the amino acid sequence from 24 to 34 of SEQ ID NO: 2, CDR2 consisting of the amino acid sequence from 50 to 56 of SEQ ID NO: 2, and CDR3 consisting of the amino acid sequence from 89 to 97 of SEQ ID NO: 2; or (2) a heavy chain variable region comprising CDR1 consisting of the amino acid sequence from 31 to 35 of SEQ ID NO: 3, CDR2 consisting of the amino acid sequence from 50 to 65 of SEQ ID NO: 3, and CDR3 consisting of the amino acid sequence from 98 to 108 of SEQ ID NO: 3, and A light chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 4, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO:

4.

22. The antibody-drug conjugate or salt thereof according to claim 21, wherein the Ab is an anti-EGFR antibody or an antigen-binding fragment thereof comprising a heavy chain variable region and a light chain variable region selected from the group consisting of (1) to (3) below: (1) a heavy chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 119 of SEQ ID NO: 1 and a light chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 107 of SEQ ID NO: 2; (2) a heavy chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 119 of SEQ ID NO: 3 and a light chain variable region consisting of the amino acid sequence from amino acid numbers 1 to 107 of SEQ ID NO: 4; and (3) a heavy chain variable region and a light chain variable region that are at least 90% identical to the heavy chain variable region and light chain variable region according to (1) or (2) above.

23. The antibody-drug conjugate or salt thereof according to claim 22, wherein the Ab is an anti-EGFR antibody of IgG1 or IgG4 type.

24. The antibody-drug conjugate or salt thereof according to claim 23, wherein Ab is cetuximab.

25. The antibody-drug conjugate or salt thereof according to claim 23, wherein the Ab is an anti-EGFR antibody consisting of a heavy chain of SEQ ID NO: 1 and a light chain of SEQ ID NO:

2.

26. The antibody-drug conjugate or salt thereof according to claims 18 to 25, wherein the Ab is an antibody or antigen-binding fragment that has been post-translationally modified or in which any amino acid residue has been substituted with cysteine or a non-natural amino acid.

27. An antibody-drug conjugate represented by formula (I) or a salt thereof (wherein Ab is an anti-EGFR antibody or an antigen-binding fragment thereof comprising a heavy chain variable region and a light chain variable region according to (1) or (2) below: (1) a heavy chain variable region comprising a CDR1 consisting of the amino acid sequence from 31 to 35 of SEQ ID NO: 1, a CDR2 consisting of the amino acid sequence from 50 to 65 of SEQ ID NO: 1, and a CDR3 consisting of the amino acid sequence from 98 to 108 of SEQ ID NO: 1, and a light chain variable region comprising a CDR1 consisting of the amino acid sequence from 24 to 34 of SEQ ID NO: 2, a CDR2 consisting of the amino acid sequence from 50 to 56 of SEQ ID NO: 2, and a CDR3 consisting of the amino acid sequence from 89 to 97 of SEQ ID NO: 2; or (2) a heavy chain variable region comprising a CDR1 consisting of the amino acid sequence from 31 to 35 of SEQ ID NO: 3, a CDR2 consisting of the amino acid sequence from 50 to 65 of SEQ ID NO: 3, and a CDR3 consisting of the amino acid sequence from 98 to 108 of SEQ ID NO: 3, and a light chain variable region comprising CDR1 consisting of the amino acid sequence from amino acid numbers 24 to 34 of SEQ ID NO: 4, CDR2 consisting of the amino acid sequence from amino acid numbers 50 to 56 of SEQ ID NO: 4, and CDR3 consisting of the amino acid sequence from amino acid numbers 89 to 97 of SEQ ID NO: 4; A is a linker represented by formula (LA-3) ( *Ab indicates the binding site with Ab), b is 12, and D is a heterocyclic compound having an activity of inducing the degradation of mutant KRAS protein represented by formula (PL-1′) (wherein *LA is L A (representing the bond with m is a number between 3 and 9).

28. A pharmaceutical composition comprising the antibody-drug conjugate or salt thereof according to any one of claims 1 to 27 and a pharmaceutically acceptable excipient.

29. The pharmaceutical composition of claim 28 for use in the treatment of cancer.

30. The pharmaceutical composition of claim 29, wherein the cancer is a blood cancer or a solid cancer.

31. The pharmaceutical composition of claim 29, wherein the cancer is colon cancer, pancreatic cancer, or lung cancer.

32. The pharmaceutical composition of claim 29, wherein the cancer is a cancer expressing mutant KRAS.

33. The pharmaceutical composition according to claim 32, wherein the mutant KRAS is any one of G12V mutation, G12D mutation, and G12C mutation KRAS.

34. An antibody-drug conjugate or a salt thereof according to any one of claims 1 to 27 for use in the treatment of cancer.

35. A method for treating cancer, comprising the step of administering to a subject a therapeutically effective amount of the antibody-drug conjugate or salt thereof according to any one of claims 1 to 27.

36. Use of an antibody-drug conjugate or a salt thereof according to any one of claims 1 to 27 in the manufacture of a pharmaceutical composition for the treatment of cancer.

37. A drug-linker conjugate represented by formula (LD-1) or a salt thereof (wherein D is a heterocyclic compound having an activity of inducing mutant KRAS protein degradation, and R st1 may be substituted C 1-12 Alkylene or optionally substituted C 1-50 CLL is a partial structure cleavable in vivo, Sp is a spacer unit and is bonded to CLL and D, t is 0 or 1, Sp is bonded to the nitrogen atom of the amine or the oxygen atom of -OH contained in D to form N-Sp or O-Sp, and when the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium.

38. D is a heterocyclic compound represented by formula (II) having the activity of inducing mutant KRAS protein degradation, A is CR A , or N and R A is H or C 1-3 is alkyl, and X 1 is -CH2- or -O-, R 1 represents naphthyl which may be substituted with OH, or a group represented by the following formula (III): R 1a is H, methyl, F or Cl, R 1b is F, Cl, methyl or ethyl, R 2 is H, halogen, cyclopropyl, vinyl, or C optionally substituted with a group selected from the group consisting of OH and OCH 1-3 alkyl, and R 3 is a group selected from the group consisting of the following formulas (IV), (V), (VI), (VII), (VIII), (IX), (X), (XI), (XII) and (XIII), R 3a is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 5- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 is cycloalkyl, and R 3b is H or C 1-3 alkyl, and R 3c and R 3d is -(CH2) p CHR 3f -NR N1 R N2 ;-(CH2) p CHR 3f -OR 3g ;C 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , and -NR N1 R N2 a 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, which may be substituted with a group selected from the group consisting of: 1-3 Alkyl, C 1-3 Alkylene-OR 3g , C 1-3 Alkylene-NR N1 R N2 , -OR 3g , and -NR N1 R N2 C optionally substituted with a group selected from the group consisting of 3-6 cycloalkyl, where R 3c -(CH2) p CHR 3f -NR N1 R N2 In the case of formula (V), X 2 is -O-, -NH- or -N(C 2-3 alkyl)-, and R 3e -OC 2-3 Alkylene-NR N1 R N2 and R 3f is H, F or C 1-3 alkyl, and R 3g is H or C 1-3 alkyl, and R 3h is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or an optionally substituted 6-membered heteroaryl containing 1 to 3 nitrogen atoms, and R 3i are the same or different and represent H, OH, optionally substituted C 1-3 Alkyl, -O-optionally substituted C 1-3 Alkyl, -NH- optionally substituted C 1-3 Alkyl, -N-(optionally substituted C 1-3 alkyl) ２ , halogen, —CN, and oxo, or two R present on the same carbon atom 3i together with the adjacent carbon atom, C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a spiro ring as a group of formula (XIII), and the spiro ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo, or R present on two adjacent carbon atoms. 3i together with the two carbon atoms to form C 3-6 A ring selected from the group consisting of a cycloalkane and a 4- to 6-membered saturated heterocycle containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms may be formed to form a fused ring as a group of formula (XIII), and the fused ring may be 1-3 Alkyl, -O-(C 1-3 alkyl), OH, halogen, and oxo, or R present on two non-adjacent carbon atoms. 3i may form a bridged structure consisting of 1 to 2 carbon atoms together with the two carbon atoms, and the group of formula (XIII) which is a ring having the bridged structure is C 1-3 Alkyl, -O-(C 1-3 R is optionally substituted with 1 to 2 groups selected from the group consisting of alkyl, OH, halogen, and oxo; N1 and R N2 are the same or different and are H or C 1-3 alkyl, or R N1 and R N2 may form, together with the nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or R 3f and R N1 may form, together with the carbon atom and nitrogen atom to which they are attached, an optionally substituted 4- to 6-membered saturated heterocyclic group containing, as ring-constituting atoms, 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen, 2 is -O-, -NH-, or -N(C 1-3 alkyl)-, and X 3 is O or S, and X 4 is -CH2-, -CH2-CH2-, or -O-CH2-, n is 1 or 2, p is 1 or 2, q is an integer from 1 to 8, and R 4 are F, OH, OCH 3、 R 4a , cyclopropyl, N(R 4a )2, R 4a pyrrolidinyl optionally substituted with, and R 4a tetrahydrofuranyl optionally substituted with a group selected from the group consisting of 1-6 Alkyl; R 4b piperidinyl optionally substituted with R 4a tetrahydropyranyl optionally substituted by R 4a C optionally substituted with F 1-3 alkyl, and R 4b is C substituted with 1 to 3 F 1-3 alkyl, Y is phenylene optionally substituted with F or Cl, or pyridinediyl, L P is a group that chemically bonds Y and EUB, EUB is a group capable of binding to E3 ubiquitin ligase, CLL is a partial structure that can be cleaved in vivo, Sp is a spacer unit that binds to CLL and D, t is 0 or 1, and Sp is a group that chemically bonds to R 3 , R 4 or bonded to the nitrogen atom of an amine or the oxygen atom of —OH contained in EUB to form N-Sp or O-Sp, wherein if the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium, wherein: i) R st1 may be substituted C 1-12 alkylene, -optionally substituted C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-(OCH2CH2) a - or -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 alkylene-, a is an integer from 1 to 10, and R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, b is an integer of 2 to 20, CLL is a partial structure represented by formula (CL-1') that can be cleaved in vivo, *CO indicates the bond to the carbonyl group, R AA are each independently a group selected from the group consisting of H, methyl, isopropyl, benzyl, and —(CH2)3—NH—C(═O)—NH2, d is an integer from 2 to 4, Sp is a spacer unit represented by formula (SP-1), formula (SP-2) or formula (SP-3), and t is 1, *CLL indicates the binding site with CLL, R SP is H, or ii) R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, and R PEG is -(CH2CH2O) b -CH3, -C(=O)-C 1-6 Alkylene-NH-C(=O)-(CH2CH2O) b -CH3 or -C(=O)-(CH2CH2O) b -CH3, b is an integer of 2 to 20, CLL is a partial structure represented by formula (CL-2') that can be cleaved in vivo, *CO indicates the bond to the carbonyl group, 38. The drug-linker conjugate or salt thereof of claim 37, wherein t is 0.

39. EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is methyl, ethyl, isopropyl, isobutyl, sec-butyl, tert-butyl, C 3-6 cycloalkylmethyl, or C 3-6 is cycloalkyl, and R 6a and R 6b are the same or different and may be substituted with H or a group selected from the group consisting of OH, OCH3, and N(CH3)2; 1-6 alkyl, or R 6a , R 6b may be substituted together with the carbon to which they are attached. 3-6 may form a cycloalkane or an optionally substituted 4- to 6-membered saturated heterocyclic ring containing 1 or 2 heteroatoms selected from the group consisting of oxygen, sulfur and nitrogen as ring-constituting atoms, R 7 is an optionally substituted 4- to 6-membered saturated heterocyclic group containing 1 to 2 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen, or a 6-membered heteroaryl containing 1 to 3 nitrogen atoms; W is an optionally substituted phenylene or an optionally substituted 6-membered heteroarenediyl containing 1 to 3 nitrogen atoms as ring-constituting atoms; L P is -(L 1 -L 2 -L 3 -L 4 )- and L 1 , L 2 , L 3 , L 4 are the same or different and represent a bond, -O-, -NR L1 -, optionally substituted pyrrolidinediyl, optionally substituted piperidinediyl, optionally substituted piperazinediyl, optionally substituted C 1-3 is a group selected from the group consisting of alkylene and C═O, L1 is H or C 1-3 and Z is NH or a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring-constituting atoms, or a salt thereof.

40. A is CR A , or N and R A is H and X 1 is -O- and R 1 is a group represented by the following formula (III-a): R 2 is cyclopropyl, and R 3 is a group selected from the group consisting of the following formulas (IV), (V), and (XI): R 3a is -(CH2) p CHR 3f -NR N1 R N2 and R 3b is H and R 3c is -NR N1 R N2 C optionally substituted with 3-6 is cycloalkyl, and R 3f is H and R N1 and R N2 are the same or different and are H or C 1-3 is alkyl, and X 2 is -O- or -NH-, and X 3 is O, n is 1, p is 1, and R 4 is OCH3, N(R 4a )2, and R 4a pyrrolidinyl optionally substituted with C 1-6 alkyl; or R 4a tetrahydropyranyl optionally substituted by R 4a is C 1-3 40. The drug-linker conjugate or salt thereof of claim 39, wherein Y is alkyl and Y is phenylene.

41. EUB is a group capable of binding to VHL, and the group capable of binding to VHL is a group represented by formula (XIV): R 5 is isopropyl or tert-butyl, R 6a and R 6b are different from each other and are C optionally substituted with H or OH 1-6 alkyl, and R 7 is an optionally substituted 5-membered heteroaryl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen; W is phenylene; L P is a bond; Z is a 5-membered heteroarenediyl containing 1 to 4 heteroatoms selected from the group consisting of oxygen, sulfur, and nitrogen as ring members; Sp is R 3 or R 4 or the oxygen atom of —OH contained in EUB to form N-Sp or O-Sp, wherein when the amine is a tertiary amine, the nitrogen atom of the amine bonds with Sp to form a quaternary ammonium.

42. A is N and R 3 is a group represented by the following formula (XI): R 4 is N(R 4a )2 is substituted with C 1-6 alkyl, and R 4a is C 1-3 alkyl, and R 7 is a group represented by the following formula (XVI): W is a group represented by the following formula (XVII-a): Z is a group represented by the following formula (XVIII): R st1 may be substituted C 1-12 Alkylene-NH-, -C 1-6 Alkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 Alkylene-NH- or -C 1-6 Heteroalkylene-NH-C(=O)-C 1-6 Alkylene-N(R PEG )-C 1-6 Alkylene-C(=O)-NH-C 1-6 alkylene-NH-, and R PEG is -C(=O)-(CH2CH2O) b -CH3, b is an integer of 2 to 20, CLL is a partial structure represented by formula (CL-2') that can be cleaved in vivo, *CO indicates the bond to the carbonyl group, t is 0, Sp is R 4 N(R 4a )2 bonded to the nitrogen atom -N + (R 4a 42. The drug-linker conjugate or salt thereof of claim 41, which forms 2-Sp.

43. The drug-linker conjugate or salt thereof according to claim 37, represented by the following formula (LD-2), (LD-3) or (LD-4): (wherein b is an integer from 2 to 20).

44. The drug-linker conjugate or salt thereof of claim 43, wherein b is 12.

45. (4R)-1-[(2S)-2-{4-[4-({[(7M)-4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-2-[3-(dimethylamino)-2,2-dimethylpropoxy]-7-(6-fluoro-5-methyl-1H-indazol-4-yl)quinazolin-8-yl]oxy}methyl)phenyl]-1H-1,2,3-triazol-1-yl}-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, (4R)-1-[(2S)-2-(4-{4-[({(7M)-4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-[(oxan-4-yl)oxy]quinazolin-8-yl}oxy)methyl]phenyl}-1H-1,2,3-triazol-1-yl)-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, (4R)-1-[(2S)-2-{4-[4-({[(7M)-4-[(2S)-2-carbamoylazetidin-1-yl]-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-{[(3R)-1-methylpyrrolidin-3-yl]methoxy}quinazolin-8-yl]oxy}methyl)phenyl]-1H-1,2,3-triazol-1-yl}-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide, and (4R)-1-[(2S)-2-(4-{4-[({(7M)-6-cyclopropyl-7-(6-fluoro-5-methyl-1H-indazol-4-yl)-2-[(2S)-2-methoxypropoxy]-4-[(1-{[2-(methylamino)ethyl]carbamoyl}azetidin-3-yl)oxy]quinolin-8-yl}oxy)methyl]phenyl}-1H-1,2,A heterocyclic compound or a salt thereof having an activity of inducing the degradation of mutant KRAS proteins selected from the group consisting of [(1R)-3-triazol-1-yl)-3-methylbutanoyl]-4-hydroxy-N-{(1R)-2-hydroxy-1-[4-(1H-1,2,4-triazol-1-yl)phenyl]ethyl}-L-prolinamide,