Bispecific antibody, drug conjugate thereof, and use thereof

Abstract

A bispecific antibody, a drug conjugate thereof, and uses thereof are provided. The bispecific antibody comprises an EGFR binding domain and a HER3 binding domain. The bispecific antibody and the drug conjugate thereof provided by the invention have good endocytosis effect, proliferation inhibition activity, tumor growth inhibition activity and good in-vivo safety.

Description

Delete delete cut reward delete chirp delete chat chat chat M book Shan (10) International Publication No. WO 2025 / 016453 A1 (12) International application published under the Patent Cooperation Treaty (19) International Bureau of the World Intellectual Property Organization (43) International Publication Date January 23, 2025 (23.01.2025) WIPO I PCT (51) International Patent Classification: C07K16 / 46 (2006.01) A61K39 / 395 (2006.01) A61P35 / 00 (2006.01) A61P35 / 02 (2006.01) (21) International Application No.: (22) International Application Date: (25) Application Language: (26) Publication Language: (30) Priority: 202310895654.4 202410244954.0 202410914157.9 PCT / CN2024 / 106435 July 19, 2024 (19.07.2024) Chinese Chinese July 19, 2023 (19.07.2023) CN March 4, 2024 (04.03.2024) CN July 9, 2024 (09.07.2024) CN = _-==- === = = = ===== === (71) Applicant: DUALITY BIOLOGICS (SUZHOU) CO., LTD. [CN / CN]; Unit 301, Building 3, Phase III, Area B, Biomedical Industrial Park, No. 99 Jingu Road, Suzhou Industrial Park, Suzhou, Jiangsu 215000, China (CN)0 (72) Inventor: Zhou Yunhua; Unit 301, Building 3, Phase III, Area B, Biomedical Industrial Park, No. 99 Jingu Road, Suzhou Industrial Park, Suzhou City, Jiangsu Province, China 215000 (CN)0 Hua Haiqing; Unit 301, Building 3, Phase III, Area B, Biomedical Industrial Park, No. 99 Jingu Road, Suzhou Industrial Park, Suzhou City, Jiangsu Province, China 215000 (CN). YANG Junjie; Unit 301, Building 3, Phase III, Area B, Biomedical Industrial Park, 993 Jingu Road, Suzhou Industrial Park, Suzhou City, Jiangsu Province, China, 215000 (CN) 0 ZHU Zhongyuan; Unit 301, Building 3, Phase III, Area B, Biomedical Industrial Park, 99 Jingu Road, Suzhou Industrial Park, Suzhou City, Jiangsu Province, China, 215000 (CN) 0 (74) Agent: Shanghai BESHINING Law FirmLAW OFFICE); Room 02, 29th Floor, Foreign Economic Building, No. 681 Xiaomuqiao Road, Xuhui District, Shanghai, 200032, China (CN) 0 (81) Designated countries (unless otherwise specified, each of which requires national protection): AE, AG, AL, AM, AO, AT, AU, AZ, BA, BB, BG, BH, BN, BR, BW, BY, BZ, CA, CH, CL, CN, CO, CR, CU, CV, CZ, DE, DJ, DK, DM, DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, HN, HR, HU, ID, IL, IN, IQ, IR, IS, IT, JM, JO, JP, KE, KG, KH, KN, KP, KR, KW, KZ, LA, LC, LK, LR, LS, LU, LY, MA, MD, MG, MK, MN, MU, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, OM, PA, PE, PG, PH, PL, PT, QA, RO, RS, RU, RW, SA, SC, SD, SE, SG, SK, SL, ST, SV, SY, TH, TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, WS, ZA, ZM, ZWO (84) Designated countries (unless otherwise specified, each of the available regional protections is required): ARIPO (BW, CV, GH, GM, KE, LR, LS, MW, MZ, NA, RW, SC, SD, SL, ST, SZ, TZ, UG, ZM, ZW), Eurasia (AM, AZ, BY, KG, KZ, RU, TJ, TM), Europe (AL, AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, MC, ME, MK, MT, NL, NO, PL, PT, RO, RS, SE, SI, SK, SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, KM, ML, MR, NE, SN, TD, TG)O According to the statement in Rule 4.17:Regarding the applicant's right to apply for and be granted a patent (Detailed Rules 4.17(h)) - Inventor status (Detailed Rules 4.7(iν)) This international publication includes: - an international search report (Article 21(3) of the Treaty). - a sequence listing portion of the specification (Detailed Rules 5.2(a)). (54) Title: BISPECIFIC ANTIBODY, DRUG CONJUGATE THEREOF, AND USE THEREOF (54) Invention title: A bispecific antibody, a drug conjugate thereof, and a use thereof (57) Abstract: Provided are a bispecific antibody, a drug conjugate thereof, and a use thereof. The bispecific antibody comprises an EGFR binding domain and an HER3 binding domain. The provided bispecific antibody and the drug conjugate thereof have excellent endocytosis effects, proliferation inhibition activity and tumor growth inhibition activity, as well as good in vivo safety. (57) Abstract: Provided are a bispecific antibody, a drug conjugate thereof, and a use thereof. The bispecific antibody comprises an EGFR binding domain and a HER3 binding domain. The provided bispecific antibody and its drug conjugate exhibit excellent endocytosis effect, proliferation inhibitory activity, tumor growth inhibitory activity, and good in vivo safety. WO 2025 / 016453 PCT / CN2024 / 106435 A bispecific antibody, its drug conjugate, and its use This application claims priority to Chinese Patent Application 2023108956544, filed on 2023 / 7 / 19; Chinese Patent Application 2024102449540, filed on 2024 / 3 / 4; and Chinese Patent Application 2024109141579, filed on 2024 / 7 / 9. The full text of the above-mentioned Chinese patent applications is incorporated herein by reference. Technical Field This invention relates to the field of biotechnology, specifically to a bispecific antibody comprising an EGFR-binding domain and a HER3-binding domain, its drug conjugate, and its use. Background Art Epidermal growth factor receptor (EGFR) is a large transmembrane glycoprotein with a molecular weight of approximately 170 kDa, belonging to the ErbB receptor family.EGFR is a member of the ErbB family. The EGFR receptor itself is a tyrosine kinase that forms a dimer upon binding to ligands such as EGF and TNF-α. This dimer activates downstream signaling pathways (such as MAPK, PI3K, and Stat) through phosphorylation, thereby maintaining cell growth and promoting cell division and proliferation. Due to the conservation of ErbB family receptors, EGFR can also form heterodimers with other proteins in the family (such as HER2, HER3, and HER4), thus regulating cell growth more broadly. HER3 is a member of the ErbB family and plays a crucial role in cell proliferation, tumor metastasis, and drug resistance. Although drugs targeting EGFR and HER3 have shown significant clinical benefits in alleviating various cancers, previous efforts to develop anti-HER3 antibodies for cancer treatment have repeatedly failed. Antibody-drug conjugates (ADCs) consist of three parts: an antibody or its antigen-binding fragment (target), a linker, and a small molecule drug. Antibodies or their antigen-binding fragments are conjugated to small molecule drugs with biological activity, such as cytotoxic agents, via cleavable or non-cleavable linkers. This fully utilizes the specificity of the antibody or its antigen-binding fragment in targeting cells of interest (target cells) or the specificity in binding to highly expressed antigens, as well as the high efficiency of small molecule drugs, reducing or avoiding toxic side effects on non-target cells. This means that, compared with traditional tumor chemotherapy drugs, antibody-drug conjugates for tumors can precisely target tumor cells and reduce the impact on non-tumor cells. There is still a need in the art for bispecific antibody-drug conjugates with excellent affinity and specificity. The present invention addresses the technical problem of the limited number of bispecific antibody-drug conjugates targeting EGFR and HER3 in the prior art, and provides a bispecific antibody, its drug conjugate, and its uses. The bispecific antibody-drug conjugate of the present invention exhibits excellent endocytosis effect, proliferation inhibition activity, tumor growth inhibition activity, and good in vivo safety. The present invention mainly solves the above-mentioned technical problems through the following technical means. To address the aforementioned technical problems, the first aspect of this invention provides a bispecific antibody comprising an EGFR-binding domain and a HER3-binding domain, wherein the EGFR-binding domain includes a heavy chain variable region VH1 and a light chain variable region VL1, and the HER3-binding domain includes a heavy chain variable region VH2 and a light chain variable region VL2; wherein the amino acid sequences of H1CDRL·H1CDR2 and H1CDR3 contained in VH1 are shown in SEQ ID NO:1, SEQ ID NO:2, and SEQ ID NO:3, respectively; and the amino acid sequences of L1CDRL·L1CDR2 and L1CDR3 contained in VL1 are shown in SEQ ID NO:1, SEQ ID NO:2, and SEQ ID NO:3, respectively.As shown in SEQ ID NO:4, SEQ ID NO:5, and SEQ ID NO:6; the amino acid sequences of H2CDR1, H2CDR2, and H2CDR3 contained in VH2 are shown in SEQ ID NO:7, SEQ ID NO:8, and SEQ ID NO:9, respectively; the amino acid sequences of L2CDR1, L2CDR2, and L2CDR3 contained in VL2 are shown in SEQ ID NO:10, SEQ ID NO:11, and SEQ ID NO:12, respectively. In some embodiments of the present invention, the amino acid sequence of H2CDR2 is shown in SEQ ID NO:77 or 78. In some preferred embodiments of the present invention, the amino acid sequences of the frame regions H1FR1, H1FR2, H1FR3, and H1FR4 included in VH1 are as shown in SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, and SEQ ID NO: 16, or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with them; the amino acid sequences of the frame regions L1FR1, L1FR2, L1FR3, and L1FR4 included in VL1 are as shown in SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, and SEQ ID NO: 20, or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with them; the amino acid sequence of the frame region H2FR1 included in VH2 is as shown in SEQ ID NO: 21, or has at least 90%, 91%, or 91% identity with it. The amino acid sequences of frame regions H2FR2 and H2FR4 are as shown in SEQ ID NO:22 and SEQ ID NO:24, respectively, or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity, for example, having an E16D mutation in SEQ ID NO:21; the amino acid sequences of frame regions H2FR3 are as shown in SEQ ID NO:23, or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity, for example, having an S18D mutation in SEQ ID NO:23; the amino acid sequence of frame region L2FR1 included in said VL2 is as shown in SEQ ID NO:25, or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity, for example, having an E16D mutation in SEQ ID NO:21; 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity, for example, in SEQ ID NO:25The structure has S9D and V15L mutations, or S7E mutations; the amino acid sequences of the framework regions L2FR2, L2FR3, and L2FR4 are as shown in SEQ ID NO:18, SEQ ID NO:26, and SEQ ID NO:27, respectively, or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with them. In some embodiments of the invention, the amino acid sequence of VH1 is as shown in SEQ ID NO:28, the amino acid sequence of VL1 is as shown in SEQ ID NO:29, the amino acid sequence of VH2 is as shown in SEQ ID NO:30, SEQ ID NO:79, or SEQ ID NO:80, and the amino acid sequence of VL2 is as shown in SEQ ID NO:1, SEQ ID NO:81, or SEQ ID NO:82. In some preferred embodiments of the present invention, the amino acid sequences of VH1, VLL, VH2 and VL2 of the bispecific antibody are as shown in SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30 and SEQ ID NO:31, respectively; or, as shown in SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:79 and SEQ ID NO:81, respectively; or, as shown in SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:79 and SEQ ID NO:31, respectively; or, as shown in SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:80 and SEQ ID NO:82, respectively. In some embodiments of the present invention, the EGFR-binding domain and the HER3-binding domain further include a light chain constant region and a heavy chain constant region, respectively. The EGFR-binding domain includes a light chain constant region CL1 and a heavy chain constant region HC1, and the HER3-binding domain includes a light chain constant region CL2 and a heavy chain constant region HC2. The amino acid sequences of CL1 and CL2 are as shown in SEQ ID NO:32 or SEQ ID NO:33, or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with them, and the amino acid sequences of CL1 and CL2 are not the same. And / or, HC1 contains C1H1 and Fcl, and HC2 contains C2H1 and Fc2. The amino acid sequences of C1H1 and C2H1 are as shown in SEQ ID NO:34 or SEQ ID NO:35, or have at least...The amino acid sequences of Fcl and Fc2 are 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical, and the amino acid sequences of C1H1 and C2H1 are not the same; the amino acid sequences of Fcl and Fc2 are variant sequences of the amino acid sequence shown in SEQ ID NO:36 or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it, for example, having T146W, or SI34c and T146W, or T146S, LI48A and Y187V, or Y349C, T366S, L368A and Y407V mutations in SEQ ID NO:36, and the amino acid sequences of Fcl and Fc2 are not the same. In some preferred embodiments of the present invention, the amino acid sequences of CL1 and CL2 are as shown in SEQ ID NO:32 or SEQ ID NO:33, respectively; the amino acid sequences of C1H1 and C2H1 are as shown in SEQ ID NO:34 or SEQ ID NO:35; and the amino acid sequences of Fcl and Fc2 are variant sequences of the amino acid sequence shown in SEQ ID NO:36, for example, having T146W, or SI34c and T146W, or T146S, L148A and Y187V, or Y349C, T366S, L368A and Y407V mutations in SEQ ID NO:36. In some more preferred embodiments of the present invention, Fcl and Fc2 are connected by disulfide bonds in the money chain region and a hole-in-hole structure; wherein Fcl is a hole-Fc and Fc2 is a hole-Fc, or Fc2 is a hole-Fc and Fcl is a hole-Fc. In some further preferred embodiments of the present invention, C1H1 and Fcl, C2H1 and Fc2 are connected by a money chain region, wherein the amino acid sequence of the money chain region is as shown in SEQ ID NO:89. In some preferred embodiments of the present invention, the EGFR binding domain comprises a light chain constant region CL1 and a heavy chain constant region HC1, and the HER3 binding domain comprises a heavy chain constant region HC2; wherein the amino acid sequence of CL1 is as shown in SEQ ID NO:32 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity with it; and / or, HC1 comprises C1H1 and Fcl, and HC2 comprises Fc2; wherein the amino acid sequence of C1H1 is as shown in SEQ ID NO:34 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity with it; the amino acid sequences of Fcl and Fc2 are as shown in SEQ ID NO:34.The amino acid sequence shown in NO:36 is a variant sequence or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity with it. In some preferred embodiments of the present invention, the amino acid sequence of CL1 is as shown in SEQ ID NO:32, the amino acid sequence of C1H1 is as shown in SEQ ID NO:34, and the amino acid sequences of Fcl and Fc2 are as shown in SEQ ID NO:93 and 94, respectively; In some preferred embodiments of the present invention, Fcl and Fc2 are connected by disulfide bonds and a knob into a hole structure in the cleavage region, wherein Fcl is knob-Fc and Fc2 is hole-Fc, or Fc2 is knob-Fc and Fcl is hole-Fc; In some preferred embodiments of the present invention, C1H1 and Fcl are connected by the cleavage region as shown in SEQ ID NO:89; VL2 and VH2 are connected by the cleavage region as shown in SEQ ID NO:95; VH2 and Fc2 are connected by the cleavage region as shown in SEQ ID NO:96. In some preferred embodiments of the present invention, the bispecific antibody comprises a heavy chain H1, a light chain L1, and a heavy chain H2, wherein the amino acid sequence of H1 is as shown in SEQ ID NO:37 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it, and / or the amino acid sequence of L1 is as shown in SEQ ID NO:38 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it, and / or the amino acid sequence of H2 is as shown in SEQ ID NO:90 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it; In some preferred embodiments of the present invention, the bispecific antibody comprises a heavy chain H1, a light chain L1, and a heavy chain H2, wherein the amino acid sequences of the heavy chain H1, light chain L1, and heavy chain H2 are as shown in SEQ ID NO:37, SEQ ID NO:38, and SEQ ID NO:90, respectively, and are DBXT005-01. In some preferred embodiments of the present invention, the heavy chain H2 has an Fc+scFv structure. In some embodiments of the present invention, the bispecific antibody comprises a heavy chain H1, a light chain L1, a heavy chain H2, and a light chain L2. In some preferred embodiments of the present invention, the amino acid sequences of the heavy chain H1, light chain L1, heavy chain H2, and light chain L2 of the bispecific antibody are as shown in SEQ ID NO:37, respectively.As shown in SEQ ID NO:38, SEQ ID NO:39 and SEQ ID NO:40, it is DBXT001-01; or, as shown in SEQ ID NO:4L·SEQ ID NO:38, SEQ ID NO:42 and SEQ ID NO:40, it is DBXT001-02; or, as shown in SEQ ID NO:43, SEQ ID NO:38, SEQ ID NO:44 and SEQ ID NO:40, it is DBXT001-03; or, as shown in SEQ ID NO:45, SEQ ID NO:38, SEQ ID NO:46 and SEQ ID NO:40, it is DBXT001-04; or, as shown in SEQ ID NO:47, SEQ ID NO:48, SEQ ID NO:49 and SEQ ID NO:50, it is DBXT001-05; or, as shown in SEQ ID NO:5L· As shown in SEQ IDNO:48, SEQ IDNO:52 and SEQ IDNO:50, it is DBXT001-06; or, as shown in SEQ IDNO:53, SEQ IDNO:48, SEQ IDNO:54 and SEQ IDNO:50, it is DBXT001-07; or, as shown in SEQ IDNO:55, SEQ IDNO:48, SEQ IDNO:56 and SEQ IDNO:50, it is DBXT001-08; or, as shown in SEQ IDNO:37, SEQ IDNO:38, SEQ IDNO:57 and SEQ IDNO:58, it is DBXT002-01; or, as shown in SEQ IDNO:41, SEQ IDNO:38, SEQ IDNO:59 and SEQ IDNO:58, it is DBXT002-02; or, as shown in SEQ IDNO:43, SEQ IDNO:38, SEQ IDNO:59 and SEQ IDNO:58, it is DBXT002-02; or, as shown in SEQ IDNO:43, SEQ IDNO:59 and SEQ IDNO:50, it is DBXT001-06. As shown in SEQ IDNO:38, SEQ IDNO:60, and SEQ IDNO:58, it is DBXT002-03; or, as shown in SEQ IDNO:45, SEQ IDNO:38, SEQ IDNO:61, and SEQ IDNO:58, it is DBXT002-04; or, as shown in SEQ IDNO:47, SEQ IDNO:48, SEQ ID NO:62, and SEQ ID NO:63, it is DBXT002-05; or, 4 WO 2025 / 016453PCT / CN2024 / 106435 or, or, or, or, or, or, or, or, or, or, or, or, or, or, or, or, or, respectively as SEQ IDNO:5L· respectively as SEQ IDNO:53, respectively as SEQ IDNO:55, respectively as SEQ IDNO:37, respectively as SEQ IDNO:4L· respectively as SEQ IDNO:43, respectively as SEQ IDNO:45, respectively as SEQ IDNO:47. respectively as SEQ IDNO:5L· respectively as SEQ IDNO:53, respectively as SEQ IDNO:55, respectively as SEQ IDNO:37, respectively as SEQ IDNO:4L· respectively as SEQ IDNO:43. respectively as SEQ IDNO:45. respectively as SEQ IDNO:47, respectively as SEQ IDNO:51, SEQ IDNO:48, SEQ IDNO:48, SEQ IDNO:48, SEQ IDNO:38, SEQ IDNO:38, SEQ IDNO:38, SEQ IDNO:38, SEQ IDNO:48, SEQ IDNO:48, SEQ IDNO:48, SEQ IDNO:48, SEQ IDNO:38, SEQ IDNO:38, SEQ IDNO:38, SEQ IDNO:38, SEQ IDNO:48, SEQ IDNO:48, SEQ IDNO:64 and SEQIDNO:63 are shown as DBXT002-06; SEQ IDNO:65 and SEQIDNO:63 are shown as DBXT002-07; SEQ IDNO:66 and SEQIDNO:63 are shown as DBXT002-08; SEQ ID NO:57 and SEQ ID NO:40 As shown, it is DBXT003-01; SEQ IDNO:59 As shown in SEQ ID NO:40, it is DBXT003-02; As shown in SEQ ID NO:60 and SEQ ID NO:40, it is DBXT003-03; As shown in SEQ ID NO:61 and SEQ ID NO:40, it is DBXT003-04; As shown in SEQ ID NO:62 and SEQ ID NO:50, it is DBXT003-05; As shown in SEQ ID NO:64 and SEQ ID NO:50, it is DBXT003-06; As shown in SEQ ID NO:65 and SEQ ID NO:50, it is...DBXT003-07; DBXT003-08 as shown in SEQ ID NO:66 and SEQ ID NO:50; DBXT004-01 as shown in SEQ ID NO:67 and SEQ ID NO:68; DBXT004-02 as shown in SEQ ID NO:69 and SEQ ID NO:68; DBXT004-03 as shown in SEQ ID NO:70 and SEQ ID NO:68; DBXT004-04 as shown in SEQ ID NO:71 and SEQ ID NO:68; DBXT004-05 as shown in SEQ ID NO:72 and SEQ ID NO:73; DBXT004-06 as shown in SEQ ID NO:74 and SEQ ID NO:73; 5 WO 2025 / 016453 PCT / CN2024 / 106435 As shown in SEQ ID NO:53, SEQ ID NO:48, SEQ ID NO:75, and SEQ ID NO:73, respectively, DBXT004-07; or, as shown in SEQ ID NO:55, SEQ ID NO:48, SEQ ID NO:76, and SEQ ID NO:73, respectively, DBXT004-08. DBXT001 includes DBXT001-01 to DBXT001-08, DBXT002 includes DBXT002-01 to DBXT002-08, DBXT003 includes DBXT003-01 to DBXT003-0108, and DBXT004 includes DBXT004-01 to DBXT004-08. To solve the above-mentioned technical problems, a second aspect of the present invention provides an isolated nucleic acid, wherein the nucleic acid encodes a bispecific antibody as described in the first aspect of the present invention. To address the aforementioned technical problems, a third aspect of the present invention provides a recombinant expression vector comprising the nucleic acid as described in the second aspect of the present invention. To address the aforementioned technical problems, a fourth aspect of the present invention provides a transformant comprising, in a host cell, the nucleic acid as described in the second aspect of the present invention or the recombinant expression vector as described in the third aspect of the present invention. In some preferred embodiments of the present invention, the host cell is a eukaryotic cell, preferably a mammalian cell, such as a CHO cell. To address the aforementioned technical problems, a fifth aspect of the present invention provides a method for preparing a bispecific antibody as described in the first aspect of the present invention, the method comprising culturing the transformant as described in the fourth aspect of the present invention to obtain the bispecific antibody. HC1 is the heavy chain constant region of the first heavy chain, and HC2 is the heavy chain constant region of the second heavy chain. VH1, C1H1, and Fcl are respectively the first...The VH, CH1, and Fc regions of the heavy chain H1, CL1 and VL1 are respectively the CL and VL regions of the first light chain L1, VH2, C2H1, and Fc2 are respectively the VH, CH1, and Fc regions of the second heavy chain H2, and CL2 and VL2 are respectively the CL and VL regions of the second light chain L2. L1FRL·L1FR2, L1FR3, and L1FR4 are the frame regions of the variable regions of the first light chain, H1FRL·H1FR2, H1FR3, and H1FR4 are the frame regions of the variable regions of the first heavy chain, L2FR1, L2FR2, L2FR3, and L2FR4 are the frame regions of the variable regions of the second light chain, and H2FR1, H2FR2, H2FR3, and H2FR4 are the frame regions of the variable regions of the second heavy chain. The antibody sequences use the Kabat numbering system. This invention also provides a bispecific antibody-drug conjugate, its tautomers, enantiomers, diastereomers, or mixtures of isomers, or a pharmaceutically usable salt thereof, comprising: a bispecific antibody or its antigen-binding fragment comprising an EGFR-binding domain and a HER3-binding domain, a linker unit L, and a cytotoxic drug; wherein the bispecific antibody or its antigen-binding fragment is as described in any one of the present invention. In some embodiments, the cytotoxic drug is camptothecin and its derivatives. In some embodiments, the cytotoxic drug is a structure as shown in formula (a1), its tautomers, enantiomers, or diastereomers, 6 WO 2025 / 016453 PCT / CN2024 / 106435 where M is -IA!?. . L1 is selected from -NH-, o, and S, and L7 is connected to the connector unit L; L1 is -(C(Rla)(Rlb))m-CH2-, a C3-C6 saturated cycloalkylene group, or a 3-6 member saturated heterocyclic group, wherein the C3-C6 saturated cycloalkylene group and the 3-6 member saturated heterocyclic group are each independently optionally substituted by one or more R2a; m is selected from 1, 2, 3, and 4; the heteroatoms in the 3-6 member saturated heterocyclic group are each independently N, o, and S, and the number of heteroatoms is 1, 2, or 3; RS and R" are each independently selected from hydrogen, halogen, hydroxyl, amino, and C1-C6 alkyl, wherein the C1-C6 alkyl group is optionally substituted by one or more halogens; R2a is selected from halogen, hydroxyl, amino, and C1-C6 alkyl, wherein the C1-C6 alkyl group is optionally substituted by one or more halogens. In certain preferred embodiments of the present invention, certain groups in the compounds represented by formulas (A1), (A-2), (A-2a), or (A-2b) are defined as follows, and groups not mentioned are the same as those described in any embodiment of the present invention (hereinafter referred to as "in some embodiments"). In some embodiments, I is preferably -O- or -S-, more preferably -O-.In some embodiments, 1Λ is -(C(Ria)(Rib))m-CH2-; Rb is selected from: hydrogen, halogen, and C1-C6 alkyl; R" is selected from: hydrogen, halogen, and C1-C6 alkyl. In some embodiments, I? is -(C(Rla)(Rlb))m-CH2-; Rh is C1-C6 alkyl, preferably CLC3 alkyl; R" is selected from: hydrogen and C1-C6 alkyl, preferably selected from: hydrogen and CLC3 alkyl. In some embodiments, u is -(C(RM)(R"))m-CH2-; Ru is (R); R" is selected from: hydrogen and C1-C6 alkyl. In some embodiments, I? is -(C(Rla)(Rlb))m-CH2-; n1 is 1 or 2, preferably 1. In some embodiments, u is selected from: 1, 3, and 3cA. In some embodiments, I is a C3-C6 saturated cycloalkylene group or a 3-6 membered saturated heterocyclic group, preferably a C3-C6 saturated cycloalkylene group, wherein the C3-C6 saturated cycloalkylene group and the 3-6 membered saturated heterocyclic group are each independently and optionally substituted by one or more R2a, each R2a being independently selected from: halogens and C1-C6 alkyl groups. In some embodiments, I is optionally substituted by one or more R2a: cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl; each R2a is independently selected from: halogens and CbC6 alkyl groups. 7 WO 2025 / 016453 PCT / CN2024 / 106435 In some embodiments, in the definitions of U and Xl, the C3-C6 cycloalkylene group is cyclobutyl or cyclohexyl, preferably cyclobutyl. In some embodiments, in the definition of u, the heteroatom of the 3-6 membered heterocyclic group is each independently N or O, and the number of heteroatoms is preferably 1 or 2. In some embodiments, the C1-C6 alkyl group defined in Ra R?b and R2a is a C1-C3 alkyl group, preferably methyl. In some embodiments, the halogen defined in R, RA R" and R2a is F, Cl, Br or I, preferably F, Cl or Br. In some embodiments, in the structure shown in formula (a-1), M is -lALy.)-; I? is O; L1 is -(C(Rla)(Rlb))m-CH2- or a C3-C6 saturated cycloene alkyl group, wherein the C3-C6 saturated cycloene alkyl group is optionally substituted with one or more R2a; m is selected from 1 or 2; Ria and Rib are each independently selected from hydrogen, halogen and C1-C6 alkyl group, wherein the C1-C6 alkyl group is optionally substituted with one or more halogens; R2a is selected from halogen and CLC6 alkyl group, wherein the C1-C6 alkyl group is optionally substituted with one or more halogens. In some embodiments, m is: or in some embodiments, M is: In some embodiments, the cytotoxic drug is selected from any of the following structures: 8 WO 2025 / 016453 PCT / CN2024 / 106435In some embodiments, the linker unit L is -La-Lb-LL; wherein l is connected to the cytotoxic drug; N-C1-alkylene-C(O)- or -6-alkylene-C(O)-, preferably N-C1-6-alkylene-C(O)- or -C1-6-alkylene-C(O)-, more preferably N-. The fragments of each group defined in -La- are preferably connected to the Lb at their right ends; -La- is further preferably, wherein the a-end is connected to Ab and the b-end is connected to Lb; U- is a polypeptide of -1 to 6 natural amino acids -NH-, preferably a polypeptide of -2 to 4 natural amino acids -NH-, more preferably selected from any of the following structures: 9 WO 2025 / 016453 PCT / CN2024 / 106435 The fragments of each group defined in -Lb- are preferably connected to the Lc at their right ends; wherein the C-end is connected to La, Preferably, it is a C1-3 alkylene group, more preferably an octyl-terminus connected to the α-terminus; α-terminus- is a C1-6 alkylene group. In some embodiments, the bispecific antibody-drug conjugate of the present invention, wherein the linker unit L is, in some embodiments, the bispecific antibody-drug conjugate of the present invention, whose structure is shown in formula (A-2): where p represents the average number of links, and p is any integer or decimal from 1 to 10; preferably any integer or decimal from 3 to 9; 10 WO 2025 / 016453 PCT / CN2024 / 106435 for example 4, 4.06, 4.10, 6, 6.1L, 6.05, 7.99, 7.98 or 8; Ab and M are respectively defined as in any embodiment of the present invention; L is the linker unit L in any embodiment of the present invention. In some embodiments, the bispecific antibody-drug conjugate of the present invention, whose structure is shown in formula (a-2): where, P represents the average number of connections, and p is any integer or decimal from 1 to 10; preferably any integer or decimal from 3 to 9; for example, 4, 4.06, 4.10, 6, 6.1L, 6.05, 7.99, 7.98, or 8; Ab is a bispecific antibody or its antigen-binding fragment as described in any embodiment of the present invention; L is a linker unit L as described in any embodiment of the present invention: M is -IA!?。。。)-; I7 is -O- or -S-, and I7 is connected to L; L1 is -(C(Rla)(Rlb))m-CH2-, a C3-C6 saturated cycloalkylene group or a 3-6 member saturated heterocyclic group, wherein the C3-C6 saturated cycloalkylene group and the 3-6 member saturated heterocyclic group are each independently optionally substituted by one or more R2a; m is 1, 2, 3 or 4; the heteroatoms in the 3-6 saturated heterocyclic groups are each independently N, O or S, and the number of heteroatoms is 1, 2 or 3;Rja and RlbR2a are each independently hydrogen, halogen, hydroxyl, amino, or d96 alkyl, wherein the C1-C6 alkyl is optionally substituted with one or more halogens; R2a is selected from halogens, hydroxyl, amino, and C1-C6 alkyl, wherein the C1-C6 alkyl is optionally substituted with one or more halogens. In some embodiments, the bispecific antibody-drug conjugate of the present invention has the structure shown in formula (A-2a) or (A-2b): p (A-2a) 11 WO 2025 / 016453 PCT / CN2024 / 106435 Wherein, (A-2b), p represents the average number of links, and p is selected from any integer or decimal from 1 to 10, preferably any integer or decimal from 3 to 9; for example, 4, 4.06, 4.10, 6, 6.1L, 6.05, 7.99, 7.98 or 8; Ab is the bispecific antibody or its antigen-binding fragment as described in any embodiment of the present invention; I? is -NH-, O or S, preferably -O- or -S-; more preferably -O-; Xi is selected from C3-C6 cycloalkyl groups optionally substituted with 1, 2 or 3 R2a; X2 is selected from -(CRa)(Rlb))CH2-; m is selected from 1 or 2; Ria and Rib are each independently hydrogen, halogen, or C1-C6 alkyl groups optionally substituted with one, two, or three halogens; R2a is selected from halogens, hydroxyl groups, amino groups, and C1-C6 alkyl groups, which are optionally substituted with one or more halogens. In some embodiments, the bispecific antibody-drug conjugate of the present invention, wherein the bispecific antibody-drug conjugate N 0 0^N H H N 0 0^N H P, P, 12 WO 2025 / 016453 PCT / CN2024 / 106435 ο N H p, ο H N H N ο ο p, 13 WO 2025 / 016453 PCT / CN2024 / 106435 ο ,° N H p, 14 WO 2025 / 016453 PCT / CN2024 / 106435 p, p and wherein, p represents the average number of connections, and p is any integer or decimal from 1 to 10, preferably any integer or decimal from 3 to 9; for example, 4, 4.06, 4.10, 6, 6.11, 6.05, 7.99, 7.98, or 8; Ab is the bispecific antibody or its antigen-binding fragment as described in any embodiment of the present invention. In some embodiments, Ab is selected from the bispecific antibodies of the present invention comprising an EGFR-binding domain and a HER3-binding domain: DBXT001 (DBXT001-01~08) > DBXT002 series (DBXT002-01~08), DBXT003 series (DBXT003-01~08). 15 WO 2025 / 016453PCT / CN2024 / 106435 and DBXT004 series (DBXT004-01-08); preferably, Ab is selected from the bispecific antibodies DBXT001 series, DBXT002 series and DBXT005-01 containing EGFR binding domain and HER3 binding domain of the present invention; more preferably, Ab is selected from the bispecific antibodies DBXT001 series and DBXT005-01 containing EGFR binding domain and HER3 binding domain of the present invention; even more preferably, Ab is selected from the bispecific antibodies DBXT001-01 and DBXT005-0L containing EGFR binding domain and HER3 binding domain of the present invention. In some embodiments, Ab is the bispecific antibody DBXT005-0L containing EGFR binding domain and HER3 binding domain of the present invention. In some embodiments, the bispecific antibody drug conjugate is selected from any of the following structures: PP, where P represents the average number of links, and P is any integer or decimal from 1 to 10, preferably any integer or decimal from 3 to 9; For example, 4, 4.06, 4.10, 6, 6.1L, 6.05, 7.99, 7.98, or 8. In some embodiments, the bispecific antibody-drug conjugate is selected from any of the following structures: 16 WO 2025 / 016453 PCT / CN2024 / 106435 4.06 6 17 WO 2025 / 016453 PCT / CN2024 / 106435 6.11 7.99 8 18 WO 2025 / 016453 PCT / CN2024 / 106435 4.10 19 WO 2025 / 016453 PCT / CN2024 / 106435 798 and the bispecific antibodies DBXT001 (DBXT001-01-08) > DBXT002 (DBXT002-01-08) > DBXT003 of the present invention, which contain EGFR binding domain and HER3 binding domain. The amino acid sequences of (DBXT003-01-08) and DBXT004 (DBXT004-01-08) are as shown in the sequence listing of this invention. The antibody CDR numbering method of this invention is: Kabat numbering. In some embodiments, the bispecific antibody-drug conjugate is: 20 WO 2025 / 016453 PCT / CN2024 / 106435 p where P represents the average number of links, and P is any integer or decimal from 1 to 10, preferably any integer or decimal from 3 to 9, more preferably any integer or decimal from 4 to 6; for example, 5.99: DBXT005-01 is a bispecific antibody against EGFR and HER3, and its heavy chain H1 amino acid sequence is as shown in SEQ ID NO: 37.The amino acid sequence of the light chain L1 is shown in SEQ ID NO: 38, and the amino acid sequence of the heavy chain H2 is shown in SEQ ID NO: 90. In some embodiments, the bispecific antibody-drug conjugate is selected from the following conjugates: where p1 represents the number of links, and p1 is any integer from 1 to 10, preferably any integer from 3 to 9, more preferably any integer from 4 to 6; for example, 4, 5, or 6. DBXT005-01 is a bispecific antibody against EGFR and HER3, whose heavy chain H1 amino acid sequence is shown in SEQ ID NO: 37, the light chain L1 amino acid sequence is shown in SEQ ID NO: 38, and the heavy chain H2 amino acid sequence is shown in SEQ ID NO: 90. In some embodiments, the average number of links p of the present invention can be any integer or decimal from 1 to 10. For example, the average number of links p can be any integer or decimal from 3 to 9. For example, the average number of connections p can be any integer or decimal from 1 to 2, 2 to 3, 3 to 4, 4 to 15, 5 to 16, 6 to 7, 7 to 8, 8 to 9, 9 to 10. Preferably, the average number of connections p is 4, 4.06, 4.10, 6, 6.11, 6.05, 7.99, 7.98, or 8. In some embodiments, the number of connections p1 of the present invention is any integer from 1 to 10. For example, the number of connections p1 is any integer from 3 to 9. For example, the number of connections p1 is 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. Preferably, the number of connections p1 is 4, 5, or 6. In another aspect, the present invention provides a method for preparing a bispecific antibody-drug conjugate as described in any one of the present invention, comprising the following steps: mixing the bispecific antibody dissolved in a buffer solution with an L-cytotoxic drug linker unit dissolved in a solvent under the action of a reducing agent, thereby obtaining the bispecific antibody-drug conjugate. In some embodiments, the preparation method comprises reacting an anti-EGFR and HER3 bispecific antibody with a compound of formula X2, for example, reacting DBXT005-01 with a compound of formula X2. In some embodiments, the reducing agent is a reducing agent conventional for such reactions in the art, such as tris(2-dimethylethyl)phosphohydrochloride. In some embodiments, the buffer solution is a buffer solution conventional for such reactions in the art, such as ethylenediaminetetraacetic acid. In some embodiments, the solvent is a solvent conventional for such reactions in the art, such as dimethylacetamide. In yet another aspect, the present invention provides a pharmaceutical composition comprising a bispecific antibody as described in any one of the present invention, isolated nucleic acid as described in any one of the present invention, a recombinant expression vector as described in any one of the present invention, and a transformation as described in any one of the present invention.The pharmaceutical composition comprises, and / or a bispecific antibody-drug conjugate as described in any one of the present invention, and a pharmaceutically acceptable carrier or excipient. In another aspect, the present invention provides a method for preparing the pharmaceutical composition of the present invention, the method comprising combining a bispecific antibody-drug conjugate as described in any one of the present invention, or a pharmaceutically acceptable form thereof, or a mixture thereof, with one or more pharmaceutically acceptable carriers or excipients. In the present invention, the pharmaceutically acceptable carrier used in the pharmaceutical composition is, for example, described in Remington's Pharmaceutical Sciences (2005). In the present invention, the pharmaceutical composition may be administered in any form, provided that it achieves the prevention, relief, prevention, or cure of symptoms in a human or animal patient. For example, various suitable dosage forms may be formulated depending on the route of administration. In other embodiments, the administration of the bispecific antibody-drug conjugate as described in any one of the present invention, or the pharmaceutical composition thereof, may be combined with other treatment methods. These other treatment methods may be selected from, but are not limited to, radiotherapy, chemotherapy, immunotherapy, or combinations thereof. In another aspect, the present invention provides a pharmaceutical formulation comprising, as described in any one of the present invention, a bispecific antibody-drug conjugate (22 WO 2025 / 016453 PCT / CN2024 / 106435), or a pharmaceutically acceptable form thereof, or a mixture thereof, as an active ingredient, or a pharmaceutical composition as described in any one of the present invention. In some embodiments, the formulation is in the form of a solid dosage form, a semi-solid dosage form, a liquid dosage form, or a gaseous dosage form. In yet another aspect, the present invention provides the use of a bispecific antibody as described in any one of the present invention, an isolated nucleic acid as described in any one of the present invention, a recombinant expression vector as described in any one of the present invention, a transformant as described in any one of the present invention, a bispecific antibody-drug conjugate as described in any one of the present invention, and / or a pharmaceutical composition as described in any one of the present invention in the preparation of a medicament for treating and / or preventing cancer, preferably, said cancer being EGFR and / or HER3 positive expression cancer. In another aspect, the present invention provides a method for treating and / or preventing cancer, comprising administering to a subject in need a bispecific antibody as described in any one of the present inventions, an isolated nucleic acid as described in any one of the present inventions, a recombinant expression vector as described in any one of the present inventions, a transformant as described in any one of the present inventions, a bispecific antibody-drug conjugate as described in any one of the present inventions, and / or a pharmaceutical composition as described in any one of the present inventions; preferably, the cancer is an EGFR and / or HER3-positive cancer. In yet another aspect, the present invention provides a bispecific antibody as described in any one of the present inventions, an isolated nucleic acid as described in any one of the present inventions, a recombinant expression vector as described in any one of the present inventions, a transformant as described in any one of the present inventions, a bispecific antibody-drug conjugate as described in any one of the present inventions, and / or a pharmaceutical composition as described in any one of the present inventions.The invention relates to nucleic acids, recombinant expression vectors as described in any one of the present inventions, transformants as described in any one of the present inventions, bispecific antibody-drug conjugates as described in any one of the present inventions, and / or pharmaceutical compositions as described in any one of the present inventions, for the treatment and / or prevention of cancer. Preferably, the cancer is EGFR and / or HER3-positive cancer. In some embodiments, the cancers described in the present invention are selected from breast cancer, skin cancer, gastric cancer, colorectal cancer, lung cancer, esophageal cancer, biliary tract cancer, head and neck cancer, thyroid cancer, ovarian cancer, endometrial cancer, pancreatic cancer, prostate cancer, bladder cancer, gastrointestinal cancer, digestive tract cancer, cervical cancer, squamous cell carcinoma, peritoneal cancer, liver cancer, kidney cancer, thyroid cancer, leukemia, malignant lymphoma, plasmacytoma, myeloma, glioma, osteosarcoma, sarcoma, cavitary squamous cell carcinoma, and melanoma. In some embodiments, the cancers described in the present invention are preferably selected from breast cancer, colorectal cancer, skin cancer, lung cancer, esophageal cancer, and oral squamous cell carcinoma. In some embodiments, the lung cancer is preferably non-small cell lung cancer, the skin cancer is preferably squamous cell carcinoma, and the colorectal cancer is preferably rectal cancer. In another aspect, the present invention provides the use of bispecific antibodies as described in any one of the present invention, isolated nucleic acids as described in any one of the present invention, recombinant expression vectors as described in any one of the present invention, transformants as described in any one of the present invention, bispecific antibody-drug conjugates as described in any one of the present invention, and / or pharmaceutical compositions as described in any one of the present invention in the preparation of EGFR and / or HER3 inhibitors. In some embodiments, the administration methods of the present invention include, but are not limited to, oral, intravenous, subcutaneous, intramuscular, intra-articular, intra-articular (e.g., in arthritic joints), inhalation, aerosol delivery, or intratumoral administration. In some embodiments, the present invention provides the combined administration of therapeutically effective amounts of one or more therapies (e.g., treatment modalities and / or other therapeutic agents) to a subject. In some embodiments, the therapies include surgical treatment and / or radiotherapy. In some embodiments, the methods or uses provided by the present invention further include administering one or more therapies (e.g., treatment modalities and / or other therapeutic agents) to an individual. The antibody-drug conjugates of the present invention or pharmaceutically acceptable salts thereof may be used alone or in combination with other therapeutic agents in a therapy. For example, it can be co-administered with at least one other therapeutic agent. In another aspect, the present invention provides a pharmaceutical combination comprising a bispecific antibody as described in any one of the present invention, an isolated nucleic acid as described in any one of the present invention, a recombinant expression vector as described in any one of the present invention, a transformant as described in any one of the present invention, a bispecific antibody-drug conjugate as described in any one of the present invention, and / or a pharmaceutical composition as described in any one of the present invention, and one or more other therapeutic agents.In another aspect, the present invention provides a kit comprising a bispecific antibody as described in any one of the present invention, an isolated nucleic acid as described in any one of the present invention, a recombinant expression vector as described in any one of the present invention, a transformant as described in any one of the present invention, a bispecific antibody-drug conjugate as described in any one of the present invention, and / or a pharmaceutical composition as described in any one of the present invention. Unless otherwise stated, the present invention will be practiced using conventional techniques of molecular biology (including recombinant technology), microbiology, cell biology, biochemistry, and immunology, all of which are within the scope of this art. Unless otherwise expressly defined elsewhere herein, the technical terms used herein have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains. For specific definitions and terms in this art, those skilled in the art may refer to Current Protocols in Molecular Biology (Ausubel). The abbreviations for amino acid residues are standard 3-letter and / or 1-letter codes used in the art to refer to one of the 20 commonly used L-amino acids. For easier understanding of the present invention, certain technical terms are specifically defined as follows. In this invention, the term "EGFR (Epidermal Growth Factor Receptor)" refers to the receptor for epidermal growth factor (EGF) cell proliferation and signal transduction. EGFR belongs to the ErbB receptor family, which includes EGFR (ErbB-1), HER2 / c-neu (ErbB-2), HER3 (ErbB-3), and HER4 (ErbB-4). EGFR is also known as HER1 or ErbB-1; mutations or overexpression generally lead to tumorigenesis. EGFR is a glycoprotein, a tyrosine kinase receptor, permeable to the cell membrane, with a molecular weight of 170 kDa. EGFR is located on the cell membrane surface and is activated by binding to ligands, including EGF and TGFa (transforming growth factor α). Upon activation, EGFR transforms from a monomer to a dimer, although there is evidence that a dimer exists before activation. EGFR may also polymerize with other members of the ErbB receptor family for activation, such as ErbB-2 / HER2 / neu. In this invention, the term "human epidermal growth factor receptor 3 (HER3)" is also used. HER3, also known as receptor tyrosine protein kinase ErbB-3 (ErbB3), is a member of the EGFR / ErbB family. Unlike other ErbB family members HER2 and EGFR, HER3 itself does not possess kinase activity. Therefore, HER3 must bind to its kinase-active member EGFR or HER2 as a heterodimer to trigger its downstream activity. Upon binding to its natural ligand NRG1, HER3 undergoes a conformational change, heterodimerization, and phosphorylation, subsequently activating MAPK and Pκ / Akt receptors via signal transduction.And PLCy. In this invention, the term "about" when used in conjunction with a numerical value means to encompass a numerical value within a range having a lower limit of 5% less than the specified numerical value and an upper limit of 5% greater than the specified numerical value, including but not limited to ±5%, ±2%, ±1%, and ±0.1%, as these variations are suitable for carrying out the disclosed methods. In this invention, the term "and / or" should be understood to mean any one of the options or a combination of any two or more of the options. In this invention, the term "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" should be interpreted inclusively, i.e., including at least one in the quantity or element list, but also including more than one, and optionally, additional unlisted items. Only when the opposite terms are explicitly stated, such as "only one" or "exactly one," or when "consisting of one" is used in the claims, will it refer to only one listed number or one element of a list. Unless the context clearly indicates the opposite, the words "one" and "an" shall be understood as "at least one" in this invention. In this invention, the term "antibody-drug conjugate" generally refers to an antibody linked to a biologically active cytotoxic drug via a stable linker unit. In this invention, "antibody-drug conjugate" can be a bispecific antibody-drug conjugate, which can refer to the linking of a bispecific antibody or its antigen-binding fragment to a biologically active cytotoxic drug fragment via a stable linker unit. In this invention, the term "cytotoxic drug" generally refers to a toxic drug that possesses a strong chemical molecule that disrupts the normal growth of tumor cells. Cytotoxic drugs can kill tumor cells at sufficiently high concentrations. The term "cytotoxic drug" may include toxins, such as small molecule toxins or enzyme-active toxins of bacterial, fungal, plant, or animal origin, radioactive isotopes (e.g., radioactive isotopes of At2U, 19, 5, Y90, RJ86, 1, 1, 1, 1, 2, 1, 2, 1, 2, 2, 2, 2, 2, 3 ...Globulins. Antibodies can be antibodies from any class, including but not limited to IgG, IgA, IgM, IgD, and IgE, and antibodies from any subclass (e.g., IgG1, IgG2, IgG3, and IgG4). Antibodies may have a heavy chain constant region selected from, for example, IgG1, IgG2, IgG3, or IgG4. Antibodies may also have a light chain selected from, for example, kappa (k) or lambda (λ). The antibodies of the present invention can be derived from any species. The term "antibody" can include complete polyclonal antibodies, complete monoclonal antibodies, multispecific antibodies (e.g., bispecific antibodies), chimeric antibodies, humanized antibodies, human antibodies, fusion proteins containing antibodies, and any other modified immunoglobulin molecules, provided that these antibodies exhibit the desired biological activity. In the present invention, the term "antigen-binding fragment" or "antigen-binding domain" generally refers to a portion of an antibody molecule containing amino acids responsible for the specific binding between the antibody and the antigen. The portion of the antigen that is specifically recognized and bound by the antibody is called an "epitope" as described herein. As described herein, an antigen-binding domain typically comprises a variable region (VL) of the antibody light chain and a variable region (VH) of the antibody heavy chain; however, it is not necessary to include both. Fd fragments, for example, have two VH regions and generally retain some of the antigen-binding functions of the complete antigen-binding domain. Examples of antigen-binding fragments of antibodies include (1) Fab fragments, monovalent fragments having VL, VH, constant light chain (CL), and CH1 domains; (2) F(ab,)2 fragments, bivalent fragments having two Fab fragments connected by disulfide bridges of the light chain region; (3) Fd fragments having two VH and CH1 domains; (4) Fv fragments having VL and VH domains of an antibody single arm; (5) dAb fragments (Ward et al., Binding Activities of a Repertoire of Single Immunoglobulin Variable Domains Secreted From Escherichia coli, Nature 341: 544-546 (1989), which are incorporated herein by reference in their entirety), having a VH domain; (6) separated complementarity-determining regions (CDRs); (7) single-chain Fv fragments. (scFv), for example, derived from scFV-libraries. Although the two domains VL and VH of the Fv fragment are encoded by independent genes, they can be joined using a recombination method via synthetic linkers. These linkers allow for the preparation of a single protein chain (referred to as a single-stranded molecule) in which the VL and VH regions pair to form a monovalent molecule. (See, for example, Huston et al., "Protein...")Engineering of Antibody Binding Sites: Recognition of Specific Activity in an Anti-Digoxin Single-Chain Fv Analogue Produced in Escherichia coli, "Proc. NatLAcad. Sci. USA 85:5879-5883 (1988)); (8) "VHH" refers to the variable antigen-binding domain of heavy chain antibodies from camelids (camels, dromedaries, llamas, alpacas, etc.) (see Nguyen VK. et al., 2000, TheEMBO Journal, 19, 921-930; Muyldermans S., 2001, J Biotechnol., 74, 277-302 and review Vanlandschoot P. et al., 2011, Antiviral Research 92, 389-407) = VHH can also be called nanobody (Nb). In this invention, the terms "variable region," "variable domain," or "variable antigen-binding domain" generally refer to the domains of the antibody heavy or light chain involved in antibody-antigen binding. In this invention, the term "variable" generally refers to the fact that certain portions of the sequence of the antibody's variable domain vary significantly, resulting in various specific antibody binding and specificity to their specific antigens. This variability is not uniformly distributed throughout the entire variable region of the antibody. It is concentrated in three segments within the light and heavy chain variable regions, referred to as complementarity-determining regions (CDRs) or hypervariable regions (HVRs), namely LCDR1, LCDR2, LCDR3, HCDRL, HCDR2, and HCDR3. More highly conserved portions of the variable region are called framework regions (FRs). The variable domains of the natural heavy and light chains each contain four FR regions (H-FR1, H-FR2, H-FR3, H-FR4, L-FR1, L-FR2, L-FR3, L-FR4), mostly employing a β-sheet configuration, and are connected via three CDRs. Structural loop regions are connected. The CDRs in each chain are closely clustered together via FR regions and, together with CDRs from the other chain, form the antigen-binding site of the antibody. In this invention, the variable regions of the antibody or the CDRs of the antibody can be encoded or divided using various methods, such as the Kabat numbering scheme and definition rules based on sequence variability (see, Kabat et al., Protein Sequences in Immunology, 5th Edition, National Institutes of Health, Bethesda, Maryland (1991)), and the Chothia numbering scheme and definition rules based on the location of structural loop regions (see,Al-Lazikani et al. (JMol Biol 273:927-48, 1997), Lefranc et al.'s IMGT numbering scheme and definition rules based on germline V gene amino acid sequence alignment, as well as Honneger's numbering scheme (AHo's), Martin's numbering scheme, Gelfand's numbering scheme, etc., can be found in Mathieu Dondelinger et al., Understanding the Significance and Implications of Antibody Numbering and Antigen-Binding Surface / Residue Definition, Front. Immunol., 16 October 2018 » In this invention, the term "monoclonal antibody" or "monoclonal antibody" refers to an antibody derived from a basic homogeneous antibody group, that is, the individual antibodies that make up the group are identical except for a small amount of possibly naturally occurring mutations. Monoclonal antibodies are highly specific, targeting a single antigenic epitope. In contrast, conventional (polyclonal) antibody preparations typically include a large number of antibodies targeting different epitopes (or specific to different epitopes). The modifier “monoclonal” indicates the characteristic of an antibody derived from a basic homogeneous antibody group and should not be construed as requiring the antibody to be produced by any particular method. In this invention, the term “multispecific antibody” refers to an antibody containing two or more antigen-binding domains and capable of binding to two or more different epitopes (e.g., two, three, four, or more different epitopes), the epitopes being on the same or different antigens. Examples of multispecific antibodies include “bispecific antibodies” (abbreviated as bispecific antibodies) or “bispecific molecules” that bind to two different antigens or two different epitopes. Bispecific antibodies targeting EGFR and HER3 may be referred to, for example, as “anti-EGFR and HER3” or “anti-EGFR / HER3” or “EGFRxHER3” bispecific molecules, or bispecific antibodies containing an EGFR-binding domain and a HER3-binding domain, or other similar terms. In this invention, the term “Fc region” is used to define the C-terminal region of the immunoglobulin heavy chain containing at least a portion of the constant region. 26 WO 2025 / 016453 PCT / CN2024 / 106435 This terminology includes the native sequence Fc region and the variant Fc region. In some embodiments, the human IgG heavy chain Fc region extends from Cys226 or Pro230 to the terminal end of the heavy chain. However, the C-terminal lysine (Lys447) of the Fc region may or may not be present (the numbering in this paragraph is based on the EU numbering system, also known as the EU index, as in Rabat et al., Sequences of Proteins of(Immunological Interest, 5th Ed. Public Health Service, National Institutes of Health, Bethesda, MD, 1991) « In this invention, the term "knob into Hole structure" refers to the mutation of a hydrophobic amino acid in the CH3 region of the antibody Fc. One side chain amino acid of CH3 is mutated to form a larger hydrophobic amino acid (knob) to strengthen hydrophobic interactions; another side chain amino acid of CH3 is mutated to form a smaller amino acid (hole) to reduce steric hindrance. After mutation, the CH3 with the knob and the CH3 with the hole form a knob into Hole structure (KiH) through hydrophobic interactions, which is beneficial for the formation of heavy chain heterodimers. The KiH mutation mainly occurs in the internal hydrophobic amino acids of the CH3 domain; the exposed amino acids remain almost unchanged after mutation, so it does not affect the effector function of Fc or the resulting immunogenicity. The term "knob-Fc" refers to the inclusion of a T366W point mutation in the antibody Fc region to form a knob-like spatial structure. Correspondingly, "hole-Fc" refers to the inclusion of point mutations T366S, L368A, and Y407V in the Fc region of an antibody to form a hole-like spatial structure. To further promote heterodimer formation, point mutations S354c and y349c can be introduced into the knob-Fc and hole-Fc regions, respectively, to further promote heterodimer formation through disulfide bonds. Simultaneously, to weaken binding to protein A, point mutations H435R and y436F can be introduced into the hole-Fc region, respectively. In this invention, the term "humanized antibody" refers to an antibody form containing sequences derived from human and non-human (e.g., mouse, rat) antibodies. Generally, humanized antibodies contain at least one, typically two, variable domains, wherein all or almost all of the variable domains correspond to the variable domains of non-human immunoglobulins, and all or almost all of the frame regions (FRs) are the frame regions of human immunoglobulin sequences. Humanized antibodies may optionally contain at least a portion of the constant regions (Fc) of human immunoglobulins. In this invention, "isotype" antibody refers to a class of antibodies (e.g., IgM, IgE, IgG such as IgG1, IgG2, or IgG4) provided by heavy chain constant region genes. Isotype also includes modified forms of one of these classes, wherein modifications have been generated to alter Fc function, for example, to enhance or weaken effector function or binding to the Fc receptor. In this invention, the term "cross-reactivity" refers to the binding of antigen fragments to the same target molecule in human, monkey, and / or mouse (mouse or rat) sources. Therefore, "cross-reactivity" should be understood as the binding of an antigen-binding molecule (e.g., antibody) to an antigen expressed in different species.Interspecies reactions of class molecules (e.g., BDCA2). The cross-reactivity specificity of monoclonal antibodies recognizing human BDCA2, monkey, and / or mouse BDCA2 (mouse or rat) can be determined by FACS analysis. In this invention, "affinity" or "binding affinity" refers to the inherent binding affinity that reflects the interaction between the bound members. The affinity of molecule X for its partner Y can generally be represented by the equilibrium dissociation constant (KD), which is the ratio of the dissociation rate constant to the binding rate constant (Kf(Kd) and ru(Ka)). Affinity can be measured by common methods known in the art. In some embodiments of the invention, surface plasmon resonance (SPR) technology is used to measure affinity, for example, the affinity between the antibody and the antigen of the present invention. In some preferred embodiments of the invention, a specific method for measuring affinity is the BIAcore method. In the present invention, the term "non-binding" protein or cell means not binding to a protein or cell, or not binding to it with a high affinity, i.e., the KD of the bound protein or cell is 1.0 x 10-6 M or higher, preferably 1.0 x 10-5 M or higher, more preferably 16 x 10-4 M or higher, 1.0 x 10-1 M or higher, and even more preferably 1.0 x 10-2 M or higher. In this invention, the term "high affinity" for IgG antibodies refers to a KD of 1.0 x 10⁻⁶ M or lower for the antigen, preferably 5.0 x 10⁻⁸ M or lower, more preferably 1.0 x 10⁻⁸ M or lower, 5610⁻⁹ M or lower, and even more preferably 1.0 x 10⁻⁸ μ or lower. For other antibody subtypes, "high affinity" binding may vary. For example, "high affinity" binding for IgM subtypes refers to a KD of 10 μ μ or lower, preferably 10 μ μ or lower, more preferably 10 μ M or lower. In this invention, the term "percentage (%) amino acid sequence identity," or simply "identity," is defined as the percentage of identical amino acid residues in a candidate amino acid sequence to those in a reference amino acid sequence after aligning the amino acid sequences (and, where necessary, introducing vacancies) to obtain the maximum percentage sequence identity, without considering any conserved substitutions as part of the sequence identity. Sequence alignment can be performed using various methods in the art to determine the percentage amino acid sequence identity, for example, using publicly available computer software such as BLAST, BLAST-2, ALIGN, or MEGALIGN (DNASTAR) software. Those skilled in the art can determine suitable parameters for measuring the alignment, including any algorithm required to obtain the maximum alignment of the full length of the compared sequences. In this invention, the term "halogen" generally refers to fluorine, chlorine, bromine, or iodine; for example, it can be fluorine or chlorine.In this invention, the term "alkyl" generally refers to a residue derived from an alkane by removing a hydrogen atom. The term "alkyl" generally refers to a saturated straight-chain or branched aliphatic alkyl group having residues derived from the removal of hydrogen atoms from the same carbon atom or two different carbon atoms of the parent alkane. It can be a straight-chain or branched group containing 1 to 20 carbon atoms, for example, containing 1 to 12 carbon atoms, such as a chain alkyl containing 1 to 6 carbon atoms, such as a chain alkyl containing 1 to 3 carbon atoms. Non-limiting examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl, propyl, butyl, etc. Alkyl groups can be substituted or unsubstituted, substituent or non-substituent; for example, when substituted, the substituent can be substituted at any usable linking point. In this invention, the term "alkylene" generally refers to a saturated straight-chain or branched aliphatic alkyl group having two residues derived from the removal of two hydrogen atoms from the same carbon atom or two different carbon atoms of a parent alkane. It can be a straight-chain or branched group containing 1 to 20 carbon atoms. For example, the term "methylene" can refer to a residue derived from the removal of two hydrogen atoms from a 1-carbon group. The methylene group can be substituted or unsubstituted, substituted or non-substituted; for example, containing 1 to 12 carbon atoms, such as an alkylene group containing 1 to 6 carbon atoms. Non-limiting examples of alkylene groups include, but are not limited to, methylene (-Oh-), 1,1-ethylene (-CH(CH3)-), 1,2-ethylene (-CH2cH2)-, 1,1-propylene (-CH(CH2cH3)-), 1,2-propylene (-CH2cH(CH3)-), 1,3-propylene (-CH2cH2cH2-), 1,4-butylene (-CH2cH2cH2cH2-), and 1,5-butylene (-CH2cH2cH2cH2-). In this invention, the term "cycloalkyl" refers to a saturated or partially unsaturated monocyclic or polycyclic cyclic substituent, wherein the cycloalkyl ring comprises 3 to 20 carbon atoms, preferably 3 to 12 carbon atoms, more preferably 3 to 10 carbon atoms, more preferably 3 to 8 carbon atoms, and more preferably 3 to 6 carbon atoms. Non-limiting examples of monocyclic cycloalkyl groups include cyclopropane, cyclobutane, cyclopentane, cyclopentenyl, cyclohexane, cyclohexenyl, cyclohexadienyl, cycloheptane, cycloheptanetrienyl, cyclooctane, etc.; polycyclic cycloalkyl groups include spirocyclic, fused-ring, and bridged-ring cycloalkyl groups. The term "cycloalkylene" refers to a divalent group connected to the remainder of the molecule by two single bonds, the rest of which is defined as "cycloalkyl". In this invention, the term "partially unsaturated" generally refers to a cyclic structure containing at least one double or triple bond between the ring molecules. The term "partially unsaturated" covers cyclic structures with multiple unsaturations, but is not intended to include aromatic or heteroaromatic rings as defined in this invention. The term "unsaturated" indicates that a portion has one or more degrees of unsaturation.In this invention, the term "heterocyclic group" refers to a saturated or partially unsaturated monocyclic or polycyclic light substituent comprising 3 to 20 ring atoms, wherein one or more ring atoms are heteroatoms selected from nitrogen, oxygen, or sulfur, and the remaining ring atoms are carbon. Preferably, it comprises 3 to 12 ring atoms, wherein 1 to 4 are heteroatoms; more preferably, it comprises 3 to 8 ring atoms, wherein 1 to 3 are heteroatoms; even more preferably, it comprises 3 to 6 ring atoms, wherein 1 to 3 are heteroatoms; most preferably, it comprises 5 or 6 ring atoms, wherein 1 to 3 are heteroatoms. Non-limiting examples of monocyclic heterocyclic groups include pyrrolidinyl, tetrahydropyranyl, piperazine, morphoyl, thiomorphoyl, and homopiperazinyl groups, etc. Polycyclic heterocyclic groups include spirocyclic, fused-ring, and bridged-ring heterocyclic groups. The heterocyclic ring may be fused to an aryl, heteroaryl, or cycloalkyl ring, and the ring connected to the parent structure is a heterocyclic group. The term "heteroalkylene" refers to a divalent group connected to the remainder of the molecule via two single bonds, the rest of which is defined as "cycloalkylene". In this invention, the term "independently" generally means that the variable applies to any situation, regardless of the presence or absence of variables with the same or different definitions in the same compound. For example, the variable may refer to the type or number of substituents in the compound, or the types of atoms in the compound. For example, when R appears twice in a compound and R is defined as "independently carbon or nitrogen", both Rs can be carbon, both Rs can be nitrogen, or one R can be carbon and the other R can be nitrogen. In this invention, the terms "optionally" or "optionally" generally mean that the event or environment described subsequently may, but does not necessarily, occur; this description includes the case where the event or environment occurs or does not occur. For example, "optionally alkyl-substituted heterocyclic groups" means that alkyl substitution may but is not required; this description can include cases where the heterocyclic group is alkyl-substituted and cases where the heterocyclic group is not alkyl-substituted. In this invention, the term "substituted" generally refers to one or more hydrogen atoms in a group, for example, up to five, or for example, one to three hydrogen atoms, independently substituted by the corresponding number of substituents. Substituents are only in their possible chemical positions, and those skilled in the art can determine (by experiment or theory) possible or impossible substitutions without much effort. For example, an amino or hydroxyl group with free hydrogen may be unstable when bonded to a carbon atom with an unsaturated (e.g., olefinic) bond. In this invention, unless specifically stated otherwise, the "linkage" between groups can generally be in either orientation; the "linkage" of group X to group Y can generally be in either orientation, where either orientation generally means that when group X is used as a linker for groups Y and Z, two or more linking sites of group X can be arbitrarily linked to group Y or group Z. In this invention, as those skilled in the art will understand, terms such as "alkyl," "cycloalkyl," etc., can be preceded by a prefix.The designation indicates the number of atoms present in a group under specific conditions, such as C1-C4 alkyl, C3-C7 cycloalkoxy, C1-C4 alkyl-carrying amino, etc., where the subscript number following "C" indicates the number of carbon atoms present in the group. For example, C3 alkyl refers to an alkyl group having three carbon atoms (e.g., n-propyl, isopropyl); in C10, members of the group can have any number of carbon atoms falling within the range of 1-10. In this invention, the compounds or antibody-drug conjugates of this invention comprise their tautomers, mesosomes, racemates, enantiomers, and / or diastereomers. In this invention, the term "diastereomer" generally refers to a stereoisomer having two or more chiral centers and whose molecules are not mirror images of each other. Diastereomers can have different physical properties, such as melting point, boiling point, spectroscopic properties, and reactivity. In this invention, the terms "tautomer" or "tautomer form" are used interchangeably and generally refer to structural isomers of different energies that can be interconverted through a low energy barrier. For example, proton tautomers (also known as prototropic tautomers) include interconversions via proton migration, such as keto-enol isomerization and imine-enamine isomerization. Valence tautomers include interconversions via the rearrangement of some bonding electrons. In this invention, the term "meta-racemate" generally refers to a molecule containing asymmetric atoms but possessing symmetry factors that result in zero total optical rotation within the molecule. The term "racemate" or "racemic mixture" refers to a composition consisting of equimolar amounts of two enantiomers. In this invention, the term "linker unit" or "linker structure" generally refers to a chemical structural fragment or bond that is connected to a ligand at one end and to a cytotoxic drug at the other end. It may also refer to the linker being connected to other linkers before being linked to a cytotoxic drug. The direct or indirect linking to the ligand can mean that the group is directly connected to the ligand via a covalent bond, or it can mean that the ligand is connected via a linker structure. For example, chemical structural fragments or bonds containing acid-labile linker structures (e.g., glandular), protease-sensitive (e.g., peptidase-sensitive), light-labile linker structures, dimethyl linker structures, or disulfide-containing linker structures can be used as linker structures. In this invention, the term "optionally linked to other molecular parts" generally means that the structure is not linked to any other chemical structure, or that the structure is linked to one or more other chemical structures different from the structure itself (e.g., the ligands described in this invention) (e.g., via chemical bonds or via linker structures).In this invention, the term "drug load" generally refers to the average number of cytotoxic drugs (payloads) loaded onto each ligand, or it can be expressed as the drug / antibody ratio (DAR). The range of cytotoxic drug load can be 0-12 per ligand (Ab), for example, 1-10 cytotoxic drugs. In embodiments of this invention, the drug load is expressed as p or p1, and can be, exemplarily, an average of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. The drug load of each ADC molecule after the conjugation reaction can be identified using conventional methods such as UV / visible spectroscopy, mass spectrometry, ELISA assays, and HPLC characterization. In this invention, certain atoms of the compounds or antibody-drug conjugates of this invention may appear in more than one isotopic form. For example, hydrogen may exist as gas (Ή), M (¾), and fluorine (3h), and carbon may exist naturally in three different isotopes (i2c, 13c, and 14C). Examples of isotopes that can be incorporated into the compounds of the present invention include, but are not limited to, 15N, 0, 17O, 12, 32p, 33p, 1291, 0, 1231, 0, 1251, or similar isotopes. Therefore, the compounds or antibody-drug conjugates of the present invention can be enriched in one or more of these isotopes relative to their natural abundance. As is known to those skilled in the art, such isotope-enriched compounds can be used for a variety of purposes. For example, substitution with a heavy isotope such as zeolite (2H) may provide certain therapeutic advantages, which could be due to greater metabolic stability. For example, the natural abundance of zeolite (2H) is about 0.015%. Therefore, there is approximately one gas atom for every 6500 hydrogen atoms in nature. Therefore, the gas abundance of the compounds or antibody-drug conjugates of the present invention is greater than 0.015% at one or more sites (as the case may be). Unless otherwise specified, the structures described in the present invention may also include compounds or antibody-drug conjugates that differ only in the presence or absence of one or more isotope-enriched atoms. For example, compounds or antibody-drug conjugates whose remaining structure is identical to that of the present invention, except that hydrogen atoms are replaced by fluorine or niobium, or carbon atoms are replaced by carbon-13 or carbon-14, are all within the scope of the present invention. In this invention, the term "pharmaceutical composition" generally refers to a mixture containing one or more of the compounds described in this invention or their physiologically / pharmaceutical salts or prodrugs, along with other chemical components, such as physiologically / pharmaceutical carriers and excipients. Pharmaceutical compositions can facilitate administration to organisms, promote the absorption of the active ingredient, and thus exert biological activity. Conventional preparation methods for pharmaceutical compositions can be found in the pharmacopoeias of various countries. Pharmaceutical compositions can be in the form of sterile injectable aqueous or oil suspensions for intramuscular and subcutaneous administration. They can be prepared according to...The suspension is prepared using suitable dispersants or wetting agents and suspending agents. The sterile injectable formulation may also be a sterile injectable solution or suspension prepared in a non-toxic, parenteral-acceptable diluent or solvent, such as a solution prepared in 1,3-butanediol. Alternatively, sterile fixative oils can be conveniently used as solvents or suspension media. For example, any blended fixative oil, including synthetic mono- or diglycerides of glycerol, can be used. Furthermore, fatty acids such as oleic acid can also be used to prepare injectable formulations. In this invention, the term "pharmaceuticalally acceptable salt" or "medicinal salt" generally refers to a salt of the compounds or antibody-drug conjugates of this invention, which may be safe and / or effective when used in mammals and may have the desired biological activity, and the compounds or antibody-drug conjugates of this invention may form salts with acids. In this invention, the term "pharmaceuticalally acceptable carrier" generally refers to a carrier or delivery system for administering therapeutic agents, such as antibodies or peptides, genes, and other therapeutic agents. This term refers to any pharmaceutical carrier that does not induce the production of antibodies harmful to the individual receiving the composition and can be administered without causing excessive toxicity. Suitable carriers can be large, slowly metabolized macromolecules, such as proteins, polysaccharides, polylactic acid, polyglycolic acid, polyamino acids, amino acid copolymers, lipid aggregates, and inactivated viral particles. These carriers are well known to those skilled in the art. Pharmaceutically acceptable carriers in therapeutic compositions may include liquids such as water, saline, glycerol, and ethanol. These carriers may also contain excipients such as wetting agents or emulsifiers, pH buffers, etc. In this invention, the terms "treatment" and "treating" generally refer to a method of obtaining a beneficial or desired outcome, including but not limited to therapeutic benefits. Therapeutic benefits include, but are not limited to, eradicating, suppressing, reducing, or improving the underlying disorder being treated. Additionally, therapeutic benefits are achieved by eradicating, suppressing, reducing, or improving one or more physiological symptoms associated with the underlying disorder, thereby observing improvement in the patient, although the patient may still have the underlying disorder. In this invention, the terms "prevention" and "preventing" generally refer to a method of obtaining a beneficial or desired outcome, including but not limited to preventive benefits. For the purpose of preventing benefits, a pharmaceutical composition may be administered to a patient at risk of developing a specific disease or to a patient reporting one or more physiological symptoms of a disease, even if the disease has not yet been diagnosed. In this invention, the terms "subject" or "patient" generally refer to a human being (i.e., a male or female of any age group, e.g., a pediatric subject (e.g., an infant, child, adolescent) or an adult subject (e.g., a young adult, middle-aged adult, or elderly person)) and / or others.Primates (e.g., cynomolgus monkeys, rhesus monkeys); mammals, including commercially relevant mammals such as cattle, pigs, horses, sheep, goats, cats, and / or dogs; and / or birds, including commercially relevant birds such as chickens, ducks, geese, quails, and / or turkeys. In this invention, the terms "therapeutic effective amount," "therapeutic effective dose," and "effective amount" refer to the amount by which the compound or antibody-drug conjugate of this invention, alone or in combination with other therapeutic agents, effectively prevents or improves the symptoms of one or more diseases or conditions, or the development of such diseases or conditions, when administered to cells, tissues, or subjects. A therapeutic effective dose also refers to a dose sufficient to result in symptom improvement, such as an amount that treats, cures, prevents, or improves an associated medical condition, or increases the rate of treatment, cure, prevention, or improvement of such conditions. When an individual is administered a single active ingredient, the therapeutic effective dose refers only to that ingredient. When administered in combination, the therapeutic effective dose refers to the combined amount of active ingredients that produce a therapeutic effect, whether administered in combination, sequentially, or simultaneously. An effective dose of the therapeutic agent will result in an increase of at least 10%, typically at least 20%, preferably at least about 30%, more preferably at least 40%, and most preferably at least 50% in diagnostic criteria or parameters. In this invention, the term "cancer" refers to a group of cells exhibiting abnormally high levels of proliferation and growth. Cancer may be benign (also called a benign tumor), premalignant, or malignant. Cancer cells may be solid cancer cells or leukemia cancer cells. In this invention, the term "tumor" refers to one or more cells containing cancer. In this invention, the term "tumor growth" refers to the proliferation or growth of one or more cells containing cancer, resulting in a corresponding increase in the size or extent of the cancer. The terms "EGFR and / or HER3 positive expression cancer" and "EGFR and / or HER3 expressing cancer" have the same definition and are cancers in which cancer cells express EGFR and / or HER3, preferably expressed on the surface of cancer cells. The amino acid numbers of the antibodies of this invention are respectively numbered according to the natural sequence from the N-terminus to the C-terminus of the antibody sequence. 31 WO 2025 / 016453 PCT / CN2024 / 106435 Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention. The reagents and raw materials used in the present invention are all commercially available. The positive and progressive effects of the present invention are as follows: The bispecific antibody of the present invention has the following advantages: 1. It can simultaneously bind to EGFR and HER3 antigens and EGFR / HER3 cell lines, exhibiting superior antitumor activity compared to monoclonal antibody drugs. Compared to the parent monoclonal antibody and the control antibody SI-1X6.4, the bispecific antibody of the present invention has a better endocytic effect on human tumor cell lines T47D, NCI-H1975, and mouse CT26 cell lines that simultaneously express EGFR and HER3. 2. Compared with related monoclonal antibody combination therapy, the bispecific antibody of the present invention has the advantages of good compliance and controllable quality. 3.The stability characterization of the bispecific antibody in this invention mainly focuses on the study of monomer purity and thermal stability. After affinity purification and molecular sieve separation, the monomer content of the bispecific antibody can reach 95%. Structural and activity analyses of the antibody after heat treatment demonstrate that it maintains a good molecular conformation and complete biological activity even under harsh environments, which is beneficial for the industrial production and packaging storage of the antibody. Overall, the EGFR and HER3 bispecific antibody of this invention exhibits good molecular stability and significantly superior in vitro activity (binding molecular and cellular levels) compared to Cetuximab and EGFR. In vivo data demonstrate that in EGFR+ HER3 tumor cells, the antitumor activity of the bispecific antibody is superior to the combination therapy of EGFR and HER3 monoclonal antibodies. Therefore, the bispecific antibody of this invention has broad application prospects due to its excellent developability and activity. The bispecific antibody-drug conjugates described in any one of the present invention have in vivo antitumor effects, specifically manifested as follows: (1) better antitumor effect on human esophageal cancer cell line OE-19 with low EGFR expression and high HER3 expression; (2) better antitumor effect on human non-small cell lung cancer cell line NCKH441 with high EGFR expression and high HER3 expression; (3) better antitumor effect on human oral squamous cell carcinoma cell line CAL-27 with high EGFR expression and low HER3 expression; (4) better antitumor effect in subcutaneous xenograft model of human esophageal cancer OE-19 resistant to EGFRADC; (5) better antitumor effect in subcutaneous xenograft model of human skin cancer A431 with high EGFR expression and low HER3 expression; (6) better antitumor effect in subcutaneous xenograft model of human colon cancer SW620 with only HER3 expression and no EGFR expression; (7) better antitumor effect in subcutaneous xenograft model of human colon cancer SW48 with low EGFR expression and low HER3 expression. (8) It exhibits better tumor-suppressive effects in a subcutaneous xenograft model of non-small cell lung cancer NCLH1975 (EGFR L858R / T790M / C797s triple mutation) resistant to third-generation TKIs. Figure 1 shows the binding of the bispecific antibody and its corresponding parent monoclonal antibody to EGFR / HER3 cell lines expressing different levels. Figure 2 shows the binding of the bispecific antibody and its corresponding parent monoclonal antibody to EGFR / HER3 cell lines expressing different levels. Figure 3 shows the endocytic activity of the bispecific antibody and its corresponding parent monoclonal antibody (pHrodo method). Figure 4 shows the endocytic activity of the bispecific antibody, its corresponding parent monoclonal antibody, and the control antibody (incucyte method). Figure 5 shows the endocytic activity of the bispecific antibody, its corresponding parent monoclonal antibody, and the control antibody (incucyte method). Figure 6 shows the in vivo drug effect of the antibody-drug conjugate on OE-19 tumor-bearing mice with low EGFR expression and high HER3 expression.2025 / 016453 PCT / CN2024 / 106435 Efficacy Evaluation. Figure 7 shows the efficacy evaluation of the antibody-drug conjugate in mice bearing the NCI-H441 human non-small cell lung cancer cell line, which expresses EGFR and HER3. Figure 8 shows the efficacy evaluation of the antibody-drug conjugate in mice bearing the CAL-27 human oral squamous cell carcinoma cell line, which expresses EGFR highly and HER3 poorly. Figure 9 shows the efficacy evaluation of the bispecific antibody-drug conjugate at different DAR values ​​in NCI-H1975 tumor-bearing mice. Figure 10 shows the efficacy evaluation of the bispecific antibody-drug conjugate at different DAR values ​​in OE-19 tumor-bearing mice. Figure 11 compares the efficacy of the bispecific antibody-drug conjugate of the present invention with that of the control antibody-drug conjugate in NCI-H1975 tumor-bearing mice. Figure 12 compares the efficacy of the bispecific antibody-drug conjugate of the present invention with that of the control antibody-drug conjugate in OE-19 tumor-bearing mice. Figure 13 shows the efficacy of the bispecific antibody-drug conjugate of the present invention in mice bearing NCKH1975 tumors, cytotoxin XI. Figure 14 shows the efficacy of the bispecific antibody-drug conjugate of the present invention in mice bearing human esophageal cancer OE-19 tumors. Figure 15 shows the efficacy of the bispecific antibody-drug conjugate of the present invention in mice with human skin cancer A431 xenograft tumors that are EGFR-overexpressing and HER3-underexpressing. Figure 16 shows the efficacy of the bispecific antibody-drug conjugate of the present invention in mice with xenograft tumors of human colon cancer cell line SW620 that does not express EGFR but only expresses HER3. Figure 17 shows the efficacy of the bispecific antibody-drug conjugate of the present invention in mice with xenograft tumors of human colon cancer cell line SW48 that are EGFR-overexpressing and HER3-underexpressing. Figure 18 shows the efficacy of the bispecific antibody-drug conjugate of the present invention in mice with non-small cell lung cancer NCI-H 1975 (EGFR L858RT790M C797S triple mutation) xenograft tumors. Detailed Description of Embodiments The present invention is further illustrated below by way of examples, but the invention is not limited to the scope of the examples described. Experimental methods not specifically described in the following examples are performed according to conventional methods and conditions, or as selected according to the product instructions. Sample Testing The present invention includes all combinations of the specific embodiments described. Further embodiments of the invention and the full scope of its applicability will become apparent from the detailed description provided below. However, it should be understood that although the detailed description and specific embodiments indicate preferred embodiments of the invention, these descriptions and embodiments are provided by way of illustration only, as various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from the detailed description herein. For all purposes, all disclosures, patents and patent applications cited herein, including citations, are incorporated herein by reference in their entirety. Example 33 WO 2025 / 016453 PCT / CN2024 / 106435The following examples are provided to demonstrate and further explain some preferred embodiments and aspects of the present invention, and should not be construed as limiting its scope. Example 1: Preparation of Bispecific Antibody In the anti-EGFR / HER3 bispecific antibody of the present invention, the anti-HER3 antibody or its antigen-binding fragment was prepared according to clone 2 of hu3F8 (PCT / CN2022 / 098929), and the anti-EGFR antibody or its antigen-binding fragment was prepared according to Zalutumumab (WO2002100348). Simultaneously, based on the above antibodies, partial amino acid mutations were performed on their CDR / FR / Fc regions. The CDR region of the bispecific antibody was determined according to the Kabat numbering rules. Based on the amino acid sequence of the antibody variable region, primers were designed and PCR was constructed to obtain the VH / VK gene fragment, thus obtaining the variable region. The antibody variable region was then combined with the constant region gene fragment to construct a complete bispecific antibody sequence. After transfecting CHO cells, monoclonal antibodies anti-EGFR and anti-HER3, as well as bispecific antibodies DBXT001-01~08, DBXT002-01~08, DBXT003-01~08, DBXT004-01-08, and DBXT005-01 were obtained according to conventional expression and purification methods. Cetuximab monoclonal antibody: prepared using conventional methods; control antibody SL1X6.4: prepared according to WO2023083381A1. The antibody names and sequences are shown in Table E. Table 1: Amino Acid Sequences of Antibodies. Antibody Name Heavy Chain 1 (SEQ ID NO:) Light Chain 1 (SEQ ID NO:) Heavy Chain 2 (SEQ ID NO:) Light Chain 2 (SEQ ID NO:) anti-EGFR 83 84 / / anti-HER3 85 86 / / Cetuximab 87 88 / / SI-1X6.4 91 92 / / DBXT001-01 37 38 39 40 DBXT001-02 41 38 42 40 DBXT001-03 43 38 44 40 DBXT001-04 45 38 46 40 DBXT001-05 47 48 49 50 DBXT001-06 51 48 52 50 DBXT001-07 53 48 54 50 DBXT001-08 55 48 56 50 DBXT002-01 37 38 57 58 DBXT002-02 41 38 59 58 DBXT002-03 43 38 60 58 DBXT002-04 45 38 61 58 DBXT002-05 47 48 62 63 DBXT002-06 51 4864 63 DBXT002-07 53 48 65 63 DBXT002-08 55 48 66 63 DBXT003-01 37 38 57 40 DBXT003-02 41 38 59 40 DBXT003-03 43 38 60 40 DBXT003-04 45 38 61 40 DBXT003-05 47 48 62 50 DBXT003-06 51 48 64 50 DBXT003-07 53 48 65 50 DBXT003-08 55 48 66 50 DBXT004-01 37 38 67 68 34 WO 2025 / 016453 PCT / CN2024 / 106435 DBXT004-02 41 38 69 68 DBXT004-03 43 38 70 68 DBXT004-04 45 38 71 68 DBXT004-05 47 48 72 73 DBXT004-06 51 48 74 73 DBXT004-07 53 48 75 73 DBXT004-08 55 48 76 73 DBXT005-01 37 38 90 - Antibody Expression and Purification 1. Resuscitate CHO-K1 cells derived from ECACC and seed them in culture medium (Shanghai Aopumai Biotechnology Co., Ltd., catalog number C673017) at 8% CC·2, 37. (2. Passage culture, at the time of transfection, make the density reach 6.0406 cells / 0.1, take 1.45 x 10⁸ cells, centrifuge and discard the supernatant; 2. Add 0.5 mL of electroporation buffer to the cell pellet and mix well; 3. Add 4 plasmids in the ratio of H1:L1:H2:L2=2:3:2:3, mix the cell plasmid suspension thoroughly and add it to the electroporation tube, and place it in the electroporator for electroporation; 4. After electroporation, transfer the cells in the electroporation tube to a shake flask containing 20 mL of culture medium and incubate at room temperature for 40 min; 5. After incubation, place the shake flask in a shaker at 37.20 rpm, 8% CO₂, and after 24 hours add feed / sodium butyrate / double antibiotics (penicillin + streptomycin), and continue culturing for 4 days; 6. On the 4th day after transfection, centrifuge to collect the supernatant, and purify the supernatant by Protein A affinity chromatography (Borglon), and use sodium acetate buffer (pH 10). 3.4) Elute, collect in fractions, and send to SEC for analysis; 7. Purify the qualified fractionated eluent by gel filtration chromatography (Borglon 200, size: 16mm x 700mm), elute with kPBS, collect in fractions, and send to SEC for analysis. Replace the qualified fractionated eluent with buffer (25mM Hbis-HCl 6% Sucrose, pH 10).Store in FC medium at 6.0). Example 2 Antibody Affinity Detection (SPR) 2.1 Objective: To detect the affinity of anti-EGFR and HER3 bispecific antibodies and maternal monoclonal antibodies using Biacore T200 (Cytiva). Experimental Methods: 1. EGFR-HER3 bispecific antibody (1 μg / mL) was captured using ProA chip. The analytes were human EGFR (human EGFR, His-Avi Tag, Kactus Biosystem, EGF-HM401), serially diluted in the range of 3.125-400 nM, for a total of 8 concentrations; human HER3 (human HER3, His-AviTag, Kactus Biosystem, HER-HM403), serially diluted in the range of 6.25-200 nM, for a total of 8 concentrations; and monkey EGFR (rehsus EGFR, C-HisTag, KactusBiosystem, EGF-CM101). 1. Concentrations were serially diluted in the range of 6.25-400 nM, for a total of 8 concentrations; monkey HER3 (rhesus HER3, C-His Tag, Kactus Biosystem, HER-CM403) was serially diluted in the range of 3.125-200 nM, for a total of 8 concentrations; 2. ProA chip-captured EGFR parental monoclonal antibody analyte: human EGFR (humanEGFR, His-AviTag, KactusBiosystem, EGF-HM401) was serially diluted in the range of 6.25-400 nM, for a total of 8 concentrations; ProA chip-captured HER3 parental monoclonal antibody (3 μg / mIΌ, analyte: human HER3 (humanHER3, His-AviTag, KactusBiosystem, HER-HM403) was serially diluted in the range of 3.125-100 nM, for a total of 8 concentrations; 35 WO 2025 / 016453 PCT / CN2024 / 106435 3. Affinity data were analyzed and fitted using a 1:1 Langmuir binding mode. Affinity (KD) is the ratio of the dissociation constant (Kd) to the binding constant (Ka). The affinity results are shown in Table 2. Table 2 Affinity of bispecific and monoclonal antibodies to human monkey antigen hEGFR hHER3 rhesusEGFR rhesusHER3 KD (M) kon (1 / M s) koff (1 / s) KD (M) kon (1 / M s) koff (1 / s) KD (M) kon (1 / M s) koff (1 / s) KD(M) kon (1 / M s) koff (1 / s) Anti- EGFR 3.36 E-09 2.18 E+05 7.33 E-04 - - - Anti- HER3 - - - 4.9 3E- 10 7.68 E+05 3.79 E-04 DBXT001 -01 9.29 E-09 5.92 E+04 5.50 E-04 5.6 0E- 10 3.22 E+05 1.80 E-04 1.1 3E- 08 4.72 E+04 5.34 E-04 5.6 3E- 10 2.78E +05 1.57 E-04 Experimental conclusions: The bispecific antibody DBXT001-01 has an affinity for human EGFR that is approximately 16 times weaker than its affinity for HER3; the affinity of DBXT001-01 for human EGFR is approximately 3 times weaker than that of the maternal EGFR antibody, while the affinity of DBXT001-01 for HER3 is comparable to that of the maternal HER3 antibody. Furthermore, the affinity of DBXT001-01 for human EGFR or HER3 is comparable to that for monkey EGFR or HER3. This affinity design of the bispecific antibody can reduce the on-target toxicity of the bispecific antibody to widely distributed normal EGFR-expressing tissues. 2.2 Antibody Affinity Detection (SPR) Objective: The affinity of anti-EGFR and HER3 bispecific antibodies was detected using a Biacore T200 (Cytiva). Experimental Methods: 1. ProA chip captured SI-1X6.4 (7.5 μg / mL). The analytes were human EGFR (human EGFR, His-Avi Tag, Kactus Biosystem, EGF-HM401), serially diluted in the range of 1.17-18.75 nM, for a total of 5 concentrations; and human HER3 (human HER3, His-Avi Tag, Kactus Biosystem, HER-HM403), serially diluted in the range of 4.69-75 nM, for a total of 5 concentrations. Similarly, ProA chip captured DBXT005-01 (6 μg / mL). The analyte human EGFR was serially diluted in the range of 9.38-150 nM, for a total of 5 concentrations; and the analyte human HER3 was serially diluted in the range of 4.69-75 nM, for a total of 5 concentrations. 2. Affinity data were analyzed and fitted using a 1:1 Langmuir binding model. Affinity (KD) is the ratio of the dissociation constant (Kd) to the binding constant (Ka). Affinity results are shown in Table 3. Table 3: Affinity of Bispecific Antibody and Human Antigen hEGFR hHER3 KD (M) kon (1 / Ms) koff (l / s) KD (M)kon (1 / Ms) koff (l / s) SI-1X6.4 1.41 E-09 8.75E+05 1.24E-03 8.84E-08 2.44E+06 2.16E-01 DBXT005-01 2.16E-08 6.13E+04 1.32E-03 3.54E-09 1.74E+05 6.16E-04 Experimental conclusion: The affinity of the bispecific antibody DBXT005-01 of this invention for human EGFR is about 15 times weaker than that of the control antibody SI-1X6.4, while its affinity for HER3 is 25 times stronger than that of the control antibody SI-1X6.4. Such bispecific antibody affinity design can reduce the on-target toxicity of bispecific antibodies to normal tissues widely expressing 36 WO 2025 / 016453 PCT / CN2024 / 106435 EGFR, and enhance the affinity for tumors with high EGFR expression and low HER3 expression. Example 3: Combination of bispecific antibody and its corresponding parent monoclonal antibody with EGFR / HER3 expression levels 3.1 Test objective: To compare the affinity of DBXT001-01 and its parent monoclonal antibody for EGFR / HER3 expression levels by flow cytometry. Experimental method: 1. Establish a stable mouse CT26 monoclonal cell line (Kebai Biotechnology) expressing human EGFR and HER3. Tumor cell lines NCI-H44L·NCI-H1975 and T47D were derived from ATCC; 2. All cell lines were incubated at 37°C. 3. Harvest cells in the logarithmic growth phase and test cell viability using the trypan blue exclusion method to ensure cell viability is above 90%. After centrifugation at 1000 r / min for 5 min, discard the supernatant. 4. Wash cells once with PBS, resuspend in FACS Buffer to prepare a single-cell suspension, and adjust the cell density to 5 x 10⁶ cells / mL; 5. Add 50 μL of cell suspension to each well of a 96-well plate to make the initial concentration of the working solution 100 nm, dilute 5-fold for a total of 6 concentrations; mix well, place in 4 wells, and incubate for 40 min; 6. Wash cells 3 times with FACS Buffer, 400 μL each time, centrifuge at 1000 rpm for 5 min, and finally resuspend cells with 100 μL of FACS Buffer; 7. Add 2 μL of PE-labeled secondary antibody (PE anti-human IgG Fc Antibody), mix well, and incubate in the dark for 40 min; 8. Wash cells 3 times with FACS Buffer, 400 μL each time, centrifuge at 1000 rpm for 5 min, and finally resuspend cells with 250 μL of FACS Buffer; Fluorescence values ​​were detected by flow cytometry.The experimental results are shown in Figure 1 and Table 4. Table 4. Affinity of maternal monoclonal and penicillin antibodies to cell lines EGFR-CT26 HER3-CT26 NCI-H441 NCI-H1975 T47D EC50 (nM) Spa n EC50 (nM) Spa n EC50 (nM) Spa n EC50 (nM) Spa n EC50 (nM) Spa n Cetuximab 0.0336 109 86 Anti-EGFR 0.4141 678 7 N / AN / A 0.7311 739 4 0.5956 126 44 N / AN / A Anti-HER3 N / AN / A 0.2802 61 32 N / AN / AN / AN / AN / AN / A DBXT00 1 0 1.904 101 31 1.963 99 12 1.663 126 30 2.135 192 98 0.6289 215 5 Experimental Conclusion: DBXT001-01 has a lower affinity for bivalent parental monoclonal antibodies against EGFR or HER3 overexpressing cell lines than for bivalent parental monoclonal antibodies, and also lower affinity for cetoximab against EGFR overexpressing cell lines; however, DBXT001-01 has an affinity for tumor cell lines simultaneously expressing EGFR and HER3 that is no weaker than that of bivalent parental monoclonal antibodies. This may be beneficial in reducing the binding of bivalent antibodies to normal tissues while enhancing the binding to tumor tissues simultaneously expressing EGFR and HER3. 3.2 Affinity Experiment of Cell Lines with Different Bispecific Antibodies and Different EGFR / HER3 Expression Levels Objective: To compare the affinity of different bispecific antibodies and parental monoclonal antibodies for EGFR / HER3 cell lines with different expression levels by flow cytometry. Methods: 1. Tumor cell lines BT-474 and MDA-MB-468 were derived from ATCC; mouse CT26 monoclonal cell line stably expressing human EGFR or human HER3 was derived from Kebai Biotechnology; 2. All cell lines were cultured in complete medium at 37°C and 5% CO2; 3. Cells in the logarithmic growth phase were harvested, and cell viability was detected using the trypan blue rejection method to ensure cell viability was above 90%. After centrifugation at 1000 r / min for 5 min, the supernatant was discarded. Wash cells once with PBS, resuspend in FACS Buffer to prepare a single-cell suspension, and adjust the cell density to 5 x 10⁻⁶ cells / mL; 4. Add 50 μL of cell suspension to each well of a 96-well plate to make the initial concentration of the working solution 150 nm, dilute 4-fold for a total of 8 concentrations; mix well and incubate at 4°C for 40 min; 5. Use FACS...Cells were washed three times with FACS buffer at 400 μL each time, centrifuged at 1000 r / min for 5 min, and finally resuspended in 100 μL FACS buffer; 2 μL of PE-labeled secondary antibody (PE anti-human IgG Fc Antibody) was added, mixed well, and incubated at 4°C in the dark for 40 min; Cells were washed three times with FACS buffer at 400 μL each time, centrifuged at 1000 r / min for 5 min, and finally resuspended in 250 μL FACS buffer; Fluorescence values ​​were detected by flow cytometry. The test sample codes are shown in Table 5. Experimental results are shown in Figure 2 and Table 6. Table 5. Names of Different Components of Bispecific or Monoclonal Antibodies: EGFR Arm, HER3 Arm, SI-1X6.4, SI-1X6.4 anti-EGFR (bivalent), SI-1X6.4 anti-HER3 (bivalent), DBXT005-01 anti-EGFR Fab (monovalent), anti-HER3 scFv (monovalent), Anti-EGFR, anti-EGFR mAb (bivalent), N / A, Anti-HER3, N / A, anti-HER3 mAb (bivalent). Table 6. Affinity of Different Bispecific Antibodies and Cell Lines with Different EGFR / HER3 Expression Levels: EGFR / CT26 (EGFR+++, HER3-), HER3 / CT26 (EGFR-, HER3+++), MDA-MB-468 (EGFR+++, HER3+), BT-474 (EGFR++, HER3+++). Name: SPAN (MFI), SPAN (MFI), SPAN (MFI), SPAN (MFI), SI-1X6.4. 19146 26128 514963 23955 DBXT005-01 30622 44784 876058 40801 Anti-EGFR 22885 N / A 571785 21095 Anti-HER3 N / A 33562 11078 20649 38 WO 2025 / 016453 PCT / CN2024 / 106435 Experimental Conclusion: For cell lines with different EGFR and HER3 expression levels, DBXT005-01 showed stronger saturation antigen activity than the control antibody SI-1X6.4; and its saturation antigen activity was also stronger than that of the corresponding parent monoclonal antibody. Example 4: Antibody endocytosis activity (pHrodo method) Test objectiveThis study investigated the endocytic effect of the antibody drug targeting EGFR and HER3 in T47D cells simultaneously expressing EGFR and HER3, and compared its endocytic activity with that of the parent monoclonal antibody. Cells were co-incubated with a fixed concentration of the antibody drug and the endocytosis indicator pHrodo. The endocytic capacity of the antibody drug was evaluated by observing the fluorescence signal generated by pHrodo accompanying the antibody drug entry into the cells at different time points. Experimental Methods: 1. Cell Culture: T47D cells were cultured in RPMI-1640 medium containing 0.2 Units / mL bovine insulin and 10% FBS. 2. Cell Preparation: T47D cells in logarithmic growth phase were washed once with PBS, digested for 2-3 min, and after complete digestion, 10-15 mL of cell culture medium was added. The digested cells were eluted, centrifuged at 1000 rpm for 5 min, the supernatant was discarded, and the cells were resuspended in cell culture medium to prepare a single-cell suspension. The viable cell density was adjusted to 3 x 10⁵ cells / mL. 3. Cell Plating: Add 50 pill / well to a 96-well cell culture plate. Incubate the plate for 48 hours (37 °C, 5% CCh). 4. Sample Addition: After co-incubating the antibody drug with Fab-pHrodo to form a complex, adjust the concentration to 6 nM or 60 nM, and add the mixture to cells in 50 wells. 5. Cell Culture: Incubate the plate for 48 hours (37 °C, 5% CCh). 6. Plate Reading: At the corresponding time points, remove the 96-well cell culture plate, digest the cells, and read the cell count and fluorescence values ​​using FACS. Experimental Results (Figure 3). Experimental Conclusion: The antibody drug targeting EGFR and HER3 in this invention exhibits better endocytosis effects on T47D cells simultaneously expressing EGFR and HER3 compared to the parent monoclonal antibody. Example 5 Antibody Endocytosis Activity (Incucyte Assay) 5.1 Test Objective: To determine the endocytosis efficiency of the antibody drug targeting EGFR and HER3 of this invention compared to other antibody drugs targeting EGFR and HER3 in the NCI-H1975 cell line simultaneously expressing EGFR and HER3 and the CT26 cell line simultaneously overexpressing EGFR and HER3. Cells were co-incubated with a fixed concentration of antibody-drug conjugate and the endocytosis indicator Incucyte® Fabfluor-pH. The endocytosis ability of the antibody-drug conjugate was evaluated by continuously observing the changes in fluorescence signal of live cells for 48 hours. Experimental Methods: 1. Cell Culture: NCI-H1975 cells were cultured in RPMI 1640 medium containing 10% FBS; the CT26 cell line stably expressing EGFR and HER3 was cultured in medium containing 10% FBS.1. 1640 + 10% FBS + 10 μg / mL puromycin + 20 μg / mL blasticidin; 2. Cell preparation: Take cells in the logarithmic growth phase, wash once with PBS, digest for 2-3 min, and after complete cell digestion, add 10-15 mL of cell culture medium to wash off the digested cells, centrifuge at 1000 rpm for 5 min, discard the supernatant, add cell culture medium to resuspend the cells to make a single-cell suspension and adjust the viable cell density to 1x10⁵ cells / mL; 3. Cell plating: Add 50 μL of each cell to a 96-well cell culture plate. Incubate the culture plate overnight at 37°C (2, 5% CO2). 4. Label the antibody-drug conjugate: For high-concentration antibody labeling, dilute the test sample stock solution to 240 nM 4X working solution (final concentration 60 nM), and dilute the Incucyte® Fabfluor-pH stock solution to 720 nM 4M working solution (final concentration 180 nM). Mix thoroughly and incubate at 37°C (2, 5% CO2) for 15 minutes in the dark. For low-concentration antibody labeling, dilute the test sample stock solution to 40 nM 4X working solution (final concentration 10 nM), and dilute the Incucyte® Fabfluor-pH stock solution to 120 nM 4X working solution (final concentration 30 nM). Mix thoroughly and incubate at 37°C (2, 5% CO2) for 15 minutes in the dark. 5. Image capture analysis: The labeled working solution of the test sample was transferred to the corresponding wells of the experimental plate. The experimental plate was then transferred to the Incucyte live cell analysis device, and the scanning and imaging program was set up. Images were acquired using the Incucyte live cell analysis system. Quantification was performed at 2-hour intervals for 48 hours. The analysis results are expressed as: total fluorescence intensity (Kν×μO / image). The experimental results are shown in Figures 4a and 4b. Experimental conclusion: The antibody drug targeting EGFR and HER3 of this invention has a better endocytic effect on cells simultaneously expressing EGFR and HER3 at both high and low concentrations compared with the parent monoclonal antibody. At the same time, the antibody drug targeting EGFR and HER3 of this invention has a better endocytic effect than the control antibody SI-1X6.4 at both high and low concentrations. 5.2 Endocytosis of different bispecific antibodies on cell lines with different EGFR / HER3 expression levels (Incucyte method) Test purpose: The endocytosis efficiency of the antibody drug targeting EGFR and HER3 of this invention was tested compared with other antibody drugs targeting EGFR and HER3 in cell lines A431 and NCI-H1975 expressing different levels of EGFR and HER3, as well as in the CT26 cell line that simultaneously overexpresses EGFR and HER3. Cells were mixed with a fixed concentration of antibody drug conjugate and the endocytosis indicator reagent Incucyte® Fabfluor-pH.Co-incubation was performed, and the endocytic capacity of the antibody-drug conjugate was evaluated by continuously observing changes in fluorescence signals in live cells over 24 hours. Experimental Methods: 1. Cell Culture: A431 cells were cultured in DMEM medium containing 10% FBS; NCI-H1975 cells were cultured in RPMI 1640 medium containing 10% FBS; the CT26 cell line, which stably transfected with both EGFR and HER3, was cultured in RPMI 1640 + 10% FBS + 10 μg / mL puromycin + 20 μg / mL blasticidin. 2. Cell Preparation: Cells in logarithmic growth phase were washed once with PBS, then digested for 2-3 min. After complete digestion, 10-15 mL of cell culture medium was added to elute the digested cells. The cells were centrifuged at 1000 rpm for 5 min, the supernatant was discarded, and the cells were resuspended in cell culture medium to prepare a single-cell suspension. The viable cell density was adjusted to 1 x 10⁵ cells / mL. 3. Cell Plating: 50 μL / well was added to a 96-well cell culture plate. The plate was incubated overnight at 37°C (2.5% CO₂). 4. Labeling the antibody-drug conjugate: Mix the test sample / control working solution and the labeling reagent working solution at a 1:3 molar ratio and a 1:1 volume ratio (40 WO 2025 / 016453 PCT / CN2024 / 106435), and incubate in a cell culture incubator (37℃, 5% CO2) in the dark for 15 minutes to ensure complete conjugation. 5. Image capture and analysis: Transfer the labeled test sample working solution to the corresponding wells of the experimental plate. Transfer the experimental plate to the Incucyte live cell analyzer, set the scanning and imaging program, and acquire images using the Incucyte live cell analyzer system. Quantification is performed at 2-hour intervals for 24 hours. The analytical results are expressed as: total fluorescence intensity (IKπ×μm / image). The experimental results are shown in Figures 5A, 5B, 5C, 5D and Table 7. Table 7. Endocytosis of bispecific antibody InM in cell lines with different EGFR / HER3 expression levels after 24 hours. A431 (RCU X μn? / Image) HER3 / CT26 (RCU X μn? / Image) NCI-H1975 (RCUX μu? / Image) SK-BR-3 (RCUX μu? / Image) SI-1X6.4 38,045 76,766 15,828 2,041 DBXT005-01 130,882 309,260 77,406 7,805 Anti-EGFR 101,106 603 56,406 5,394 Anti-HER3 186 627,334 43 1,957 Experimental Conclusion:The antibody DBXT005-01 targeting EGFR and HER3 of this invention has a better endocytic effect on tumor cells expressing different levels of EGFR or HER3 compared with the control antibody. Example 6 Preparation of Bispecific Antibody Drug Conjugate (ADC) 6.1 Preparation of Linker-Cytoxin (Linker-payload) Preparation of Linker-payload XI 41 WO 2025 / 016453 PCT / CN2024 / 106435 Step 1 Under nitrogen protection, methyl methacrylate (11.0 g, 64.6 mmol) was added dropwise to a DMF (50 mL) solution of 27a (5.00 g, 43.0 mmol) and NaHCCh (10.9 g, 129 mmol) and heated to 25°C. (2) The reaction was carried out for 17 hours. TLC (PE / EA = 2 / 1) showed that the reaction was complete. The reaction solution was added to 500 mL of water and extracted twice with EA (250 mL). After separation, the solution was washed with saturated sodium chloride aqueous solution (500 mL), dried over anhydrous Na2SO4, and concentrated by column chromatography (PE:EA = 3:2) to obtain 5.1 g of colorless liquid, yield: 57.1%. In the second step, under nitrogen protection, KI2 (4.00 g, 10.9 mmol), TsOH (800 mg, 4.65 mmol) in THF (30 mL) solution was added dropwise at 0.12, and 27b (4.50 g, 21.8 mmol) in THF (10 mL) solution was added dropwise at 25°C. (2) The reaction was carried out for 2 hours. TLC (PE / EA = 1 / 2) showed that the reaction was complete. The reaction solution was added to 200 mL of water and extracted twice with EA (200 mL). Extracted twice with PE / EA (270 mL), dried over anhydrous Na2SO4, concentrated and column-pressed (PE / EA = 3 / 2) to give 1.56 g of white solid, yield: 26%. Step 3: Under hydrogen atmosphere (TC), Pd / C (80 mg) was added to a mixed solution of EtOH (8 mL) and EA (8 mL) at 27°C (800 mg, 1.55 mmol), and stirred at 0°C for 2.5 hours. LC-MS showed the reaction was complete. The reaction solution was filtered through diatomaceous earth, the filter cake was washed with EA (200 mL), concentrated, dissolved in THF (20 mL), and evaporated to dryness to give 600 mg of white solid, yield: 91%. Step 4: Under nitrogen protection at 0°C, PE / EA (250 mg, 0.47 mmol) was added to a mixed solution of EtOH (8 mL) and EA (8 mL), and stirred at 0°C (TC). DIEA (152 mg, 1.18 mmol) was added to a DMF (6 mL) solution containing HATU (214 mg, 0.56 mmol) and HATU (214 mg, 0.56 mmol).mmol), and reacted at TC for 2 hours. LCMS showed the reaction was complete. The reaction solution was added to citric acid aqueous solution (pH = 4) (150 mL), filtered, and the filter cake was washed with 175 mL of water, filtered dry, and dried with an oil pump to obtain 260 mg of brown solid, yield: 66%. Step 5: Under nitrogen protection, at TC, diethylamine (8 mL) was added dropwise to a DCM (30 mL) solution of 27e (260 mg, 0.309 mmol), and reacted at 1C for 3 hours. LCMS showed the reaction was complete. The reaction solution was added to a petroleum acid solution (600 mL) of CC, and a solid precipitated. After standing for the solid to be adsorbed to the bottom of the bottle, the solution was poured out and dried with an oil pump to obtain 90 mg of brown solid, yield: 47.1%. Step 6: Under nitrogen protection, at 0℃, diethylamine (90 mg, 0.13 mmol), K (92 mg, 0.9 mmol) and DIEA were added. HATU (74 mg, 0.19 mmol) was added to a 2.5 mL solution of DMF (50 mg, 0.39 mmol) and reacted at PC for 2 hours. LC-MS showed that the basic reaction was complete. Under CC, the reaction solution was added to a 30 mL aqueous solution of citric acid at pH 4, resulting in the precipitation of flocculent solids. After filtration and preparative chromatography (DCM / MecOH = 10 / l), 9.2 mg of pale yellow solid XI was obtained, yield: 6%. MS m / z (ESI): 1074 [M+l] 1H-NMR (400 MHz, MeOD): 7.65 (d, 1H), 7.62 (s, 1H), 7.30–7.21 (m, 5H), 6.79 (s, 2H), 5.69–5.65 (m, 1H), 5.57 (d, 1H), 5.43–5.10 (m, 3H), 4.70 (d, 2H), 4.48-4.39 (m, 2H), 4.10-4.05 (m, 1H), 4.01-3.75 (m, 5H), 3.46 (t, 2H), 3.22-3.15 (m, 2H), 3.07-3.00 (m, 1H), 2.75 (m, 1H), 2.62 (m, 1H), 2.45 (s, 3H), 2.37-2.20 (m, 6H), 2.10-2.02 (m, 2H), 2.00-1.92 (m, 2H) 1.68-1.57 (m, 6H), 1.01 (t, 3H) Preparation of Linker-payload X2 43 WO 2025 / 016453 PCT / CN2024 / 106435 The first step is to add 34a (5g, 48.0mmol)λK₂CO₃ (19.9 g, 144.0 mmol) was dissolved in DMF (20 mL), and iodine (12.3 g, 72.0 mmol) was added dropwise. The reaction was carried out at 25°C for 17 hours. TLC (PE / EA = 3 / 1) was used to determine if the reaction was complete. The reaction solution was added to water (200 mL), extracted with EA (250 mL), washed with saturated NaCl, dried over anhydrous Na₂SO₄, and concentrated by column chromatography (PE:EA = 2:1) to obtain 8.7 g of colorless liquid 34b, yield 93%. MS-ESI: m / z 195.1 [M+H]+. In the second step, 34c (7.3 g, 19.8 mmol) and TsOH (1.46 g, 8.5 mmol) were dissolved in THF (20 mL), and the mixture was protected with nitrogen and cooled to 0°C. (3, Add 43b (7.7g, 39.6mmol) of THF (10mL) solution dropwise, and after the addition is complete, 0. (2) react for 2 hours. TLC (PE / EA = 2 / 1) shows that most of the starting material has reacted. Pour the reaction solution into 100mL of water, extract with DCM (100mL), separate the layers and wash with saturated NaCl, dry with anhydrous Na2SO4 and pass through a column (PE / EA=1 / 1) to obtain 3.9 g of colorless viscous substance 34d, yield: 39%. MS-ESI: m / z 503.3 [M+H]+« In the third step, under hydrogen atmosphere, at 0. <2, add Pd / C (1g, 10 wt.%) to a mixed solution of EtOH (100 mL) and EA (100 mL) of 34d (1.9 g, 3.78 mmol), and react at (TC) for 3 hours. TLC (PE / EA=2 / 1) indicates the reaction is complete. The reaction solution was filtered through diatomaceous earth, and the filter cake was washed with EA / EtOH (1:1, 100mL x 3). The filtrate was concentrated and dissolved with THF (50mL x 3), then evaporated to dryness and repeated three times to obtain 1 g of gray solid 34e, yield: 64%. MS-ESI: m / z 435.2 [M+Na]+. In the fourth step, under nitrogen protection, DIEA (303 mg, 2.35 mmol) was added dropwise to a DMF (20mL) solution of 34e (426 mg, 1.03 mmol), KI4 (500 mg, 0.94 mmol), and HATU (429 mg, 1.13 mmol). After the addition was complete, the reaction was carried out at PC for 2 hours. LCMS indicated the reaction was complete. The reaction solution was added dropwise to 300 mL of water, stirred, allowed to stand for 5 minutes, filtered, and the filter cake was washed with DCM / MeOH (10:1, 100mL x 3). After dissolving in a 100 mL solution, the sample was dried, stirred under dryness, and subjected to column chromatography (EA:MeOH = 30:1) to obtain 600.mg yellow solid 34f, yield: 77%. MS-ESI: m / z 830.3 44 WO 2025 / 016453 PCT / CN2024 / 106435 Step 5: Under nitrogen protection, diethylamine (5 mL) was added dropwise to a 34 g (150 mg, 0.18 mmol) DCM (5 mL) solution at 0°C and reacted at 0°C for 2 hours. LCMS showed that the reaction was complete. Petroleum acid solution (100 mL x 6) was added to the reaction solution, and a solid precipitated. After standing for the solid to settle, the solution was poured off and then dried with an oil pump to obtain 120 mg of white powder. LCMS showed that the product content was 70%, yield: 76%. MS-ESI: m / z 608.3 [M+H]+ o Step 6: Under nitrogen protection, diethylamine (5 mL) was added dropwise to a 34 g (60 mg, 0.099 mmol) DCM (51 mg, 0.108 mmol) solution at 0°C for 2 hours. LCMS showed that the reaction was complete. A solution of HATU (45 mg, 0.118 mmol) in DMF (1 mL) was added to a solution of 32 mg, 0.25 mmol in DMF (1 mL) at 0 °C, and the reaction was carried out at 0 °C for 2 hours. LC-MS showed that the starting material reacted completely. The reaction solution was directly passed through a reversed-phase column with eluent ((MeCN / MeOH = 1 / 1):H2O = 60%:40%) to purify 14.8 mg of yellow solid X2, yield 14%. MS-ESI: m / z 1062.4 [M+H]+O 1H NMR (400 MHz, Methanol-d4) δ 7.69 - 7.61 (m, 2H), 7.22 - 7.16 (m, 2H), 7.16 - 7.09 (m, 3H), 6.76 (s, 2H), 5.70 - 5.64 (m, 1H), 5.60 (d, J = 16.4 Hz, 1H), 5.40 - 5.31 (m, 2H), 5.26 (d, J = 19.0 Hz, 1H), 4.65 - 4.50 (m, 7H), 4.25 - 4.16 (mJH), 3.87 (d, J = 16.7 Hz, 1H), 3.83 - 3.76 (m, 3H), 3.72 (d, J = 17.0 Hz, 2H), 3.44 (t, J = 7.1 Hz, 2H), 3.25 - 3.17 (m, 2H), 3.10 - 3.02 (m, 1H), 2.92 - 2.83 (m, 1H), 2.45 - 2.39 (m, 5H). 2.32 -2.20 (m, 5H), 1.97- 1.89(m, 2H), 1.63 - 1.50 (m, 4H), 1.34 - 1.20 (m, 6H), 0.99 (t, J = 7.3 Hz, 3H). Preparation of Linker-payload X3 OX3 45 WO 2025 / 016453 PCT / CN2024 / 106435 οο 32c ,,NH2 .CH3SO3H 41d Step 2'0 Ο OHΟ 32b32a HN- Step 4 Fmoc—NH Step 1 Fmoc—NH Step 6 Fmoc-NH Step " Step 1 Add 960 mg, 7.92 mg of bromopropene (2.00 g, 6.6 mmol) to 32a (2.00 g, 6.6 mmol) and K2cO3 (1.82 g, 13.2 mmol) in MeCN (20 mL). The reaction mixture was stirred at 20°C for 5 hours. TLC (PE / EA = 1 / 2) showed the reaction was complete. The reaction mixture was poured into 100 mL of water, the pH was adjusted to 5, and the mixture was extracted three times with EA (100 mL). The solution was dried over anhydrous sodium sulfate, and purified by column chromatography (PE / EA = 2 / 1) to obtain 1.83 g of white solid 32b, yield: 81%. In the second step, TFA (10 mL) was added to DCM (10 mL) of 32b (1.38 g, 4.02 mmol), and the mixture was stirred at 25°C for 17 hours. TLC (PE / EA = 1 / 3) showed the reaction was complete. The reaction mixture was evaporated to dryness to obtain 0.91 g of yellow viscous substance 32c, yield negligible. In the third step, 32c (910 mg, 4.87 mmol) was added to DME / H2O of NaHCO3 (613 mg, 7.3 mmol). 41d (1.92 g, 4.87 mmol) was added to 20 mL / 10 mL of MeOH and stirred at 25 °C for 3 hours. TLC (DCM / MeOH = 1 / 1) showed that the reaction was complete. The reaction solution was poured into 100 mL of water, the pH was adjusted to 5 with aq.HCl (1 N), extracted twice with EA (150 mL), dried over anhydrous sodium sulfate, and purified by column chromatography (DCM / MeOH = 20 / l) to give 1.53 g of white solid 32e, yield: 67%. MS-ESI: m / z 467.4 [M+H]+„ Fourth step: Pd / C (600 mg) was added to 32f (3 g, 5.83 mmol) of MeOH (50 mL) and stirred at 25 °C under a hydrogen balloon for 5 hours. TLC (EA) showed that the reaction was complete. The reaction solution was filtered and evaporated to dryness to give 1.9 g of white solid 32 g, Yield: 77%. 46 WO 2025 / 016453PCT / CN2024 / 106435 Step 5: Add HATU (707 mg, 1.86 mmol) to DMF (10 mL) containing 32 g (789 mg, 1.86 mmol), KI4 (900 mg, 1.69 mmol), and triethylamine (342 mg, 3.38 mmol) at 0. (Stir for 3.5 hours. TLC (EA) showed the reaction was complete. Pour the reaction solution into H2O (80 mL), extract twice with EA (100 mL), dry to anhydrous sodium sulfate, and purify by column chromatography (EA) to give 1.186 g white solid 32 h, yield: 83%. MS-ESI: m / z 842.3 [M+H]+o Step 6: Stir 32 h (1.186 g, 1.41 mmol) of DCM / diethylamine (20 mL, 20 / 1) at 25°C for 17 hours. TLC (DCM / MeOH = 10 / 1) showed the reaction was complete. Pour the reaction solution into petroleum ether (200 mL), filter to give 768 mg white solid 32 i, yield: 88%o MS-ESI: m / z 620.3 [M+H]+» Step 7: Add 32 i (676 mg, 1.09 mmol), HATU (414 mg, 1.09 mmol) was added to DMF (10 mL) containing 32e (508 mg, 1.09 mmol) and DIEA (423 mg, 3.27 mmol), and stirred at 20°C for 17 hours. TLC (PE / EA = 1 / 5) showed the reaction was complete. The reaction solution was poured into water (30 mL) and filtered. The filter cake was purified by column chromatography (DCM / MeOH = 50 / L). 5 mg of white solid 32j was obtained, yield: 44%. MS-ESI: m / z 1068.3 [M+H]+O. Step 8: A solution of 32j (482 mg, 0.451 mmol) in diethylamine / DCM (10 mL, 1 / 5) was stirred at 10°C for 17 hours. TLC (EA) showed the reaction was complete. The reaction solution was poured into PE (30 mL) and stirred at 20°C for 17 hours. TLC (EA) showed the reaction was complete. The reaction solution was poured into PE (30 mL) and stirred at 20°C for 17 hours. TLC (PE / EA = 1 / 5) showed the reaction was complete. Filtering the solution into a solution of 32k (301 mg, 0.356 mmol) and Pd(PPh3)4 (82 mg, 0.071 mmol) in THF (5 mL) yielded 301 mg of white solid 32k, yield negligible. In step nine, morphine (93 mg, 1.07 mmol) was added to 32k (301 mg, 0.356 mmol) and Pd(PPh3)4 (82 mg, 0.071 mmol) in THF (5 mL), and the mixture was stirred at 25°C for 5 hours. LC-MS showed the reaction was complete. The reaction solution yielded 108 mg of white solid 32k, yield: 38%. MS-ESI: m / z 806.3 [M+H]+… In step ten, 32k (108 mg, 0.134…) was filtered into a solution of morphine (93 mg, 1.07 mmol) and Pd(PPh3)4 (82 mg, 0.071 mmol).27 mg, 0.134 mmol) of triethylamine (41 mg, 0.402 mmol) was added to THF (2 mL) and DMF (2 mL) at 0. (Stirred for 1 hour. TLC (DCM / MeOH = 10 / 1) showed the reaction was complete. The reaction solution was directly used to prepare 15 mg of white solid X3, yield: 12%. MS-ESI: m / z 926.3 1H NMR (400 MHz, DMSO-d6) δ 12.11 (s, 1H), 8.54 - 8.42 (m, 3H), 8.27 - 8.16 (m, 2H), 7.78 (d, J = 11.0 Hz, 1H), 7.30 (s, 1H), 6.53 (s, 1H), 5.61 - 5.51 (m, 1H), 5.42 (s, 2H), 5.20 - 5.05 (m, 2H), 4.56 - 4.42 (m, 2H) 4.32 - 4.22 (m, 1H), 3.96 - 3.87 (m, 3H), 3.79 (d, J = 5.6 Hz, 2H), 3.70 (d, J = 5.9 Hz, 2H), 3.25 - 3.08 (m, 2H), 2.61 - 2.53 (m, 2H), 2.45 - 2.36 (m, 4H), 2.36 - 2.22 (m, 3H), 2.20 - 2.03 (m, 4H), 1.99 - 1.68 (m, 4H), 0.87 (t, J = 7.3 Hz, 3H). Preparation of Linker-payload X4 47 WO 2025 / 016453 PCT / CN2024 / 106435 Step 1: Pd / C (400 mg, 10 wt.%) was added to MeOH (20 mL) containing 33a (2.00 g, 2.58 mmol), and the mixture was stirred at 20°C for 5 hours. TLC (EA) showed the reaction was complete. The reaction solution was filtered and evaporated to dryness to obtain 1.3 g of white solid 33b, yield: 74%. Step 2: HATU (305 mg, 0.802 mmol) was added to DMF (5 mL) containing 33b (0.55 g, 0.802 mmol), KI4 (427 mg, 0.802 mmol), and DIPEA (310 mg, 2.40 mmol), and the mixture was stirred at 0.2°C for 2 hours. TLC (DCM / MeOH = 1 / 10) showed the reaction was complete. The reaction solution was poured into water (40 mL).The crude product was filtered through a solution of DCM (360 mg, 0.326 mmol) and purified by column chromatography (DCM / MeOH = 20 / l) to give 360 ​​mg of yellow solid 33c, yield 41%. In the third step, diethylamine (2 mL) was added to 10 mL of DCM containing 33c (360 mg, 0.326 mmol). The solution was heated to 25°C. (Stirred for 17 hours. TLC (DCM / MeOH = 5 / l) showed the reaction was complete. The reaction solution was poured into PE (100 mL) and filtered to obtain 205 mg of white solid 33d, yield: 71% MS-ESI: m / z 881.3 [M+H]+o Fourth step: Add 2 mL of THF (94 mg, 0.446 mmol) solution to DMF (1 mL) and water (1 mL) of 33d (205 mg, 0.233 mmol) and triethylamine (118 mg, 1.17 mmol), and stir at 0 degrees for 1 hour. The reaction solution directly prepared 15 mg of white solid X4, yield: 6% « 48 WO 2025 / 016453 PCT / CN2024 / 106435 MS-ESI: m / z 1001.2 1H NMR (400 MHz, DMS0-d6) δ 8.57 - 8.50 (m, 1H), 8.50 - 8.43 (m, 2H), 8.35 - 8.29 (m, 1H), 8.19 - 8.12 (m, 2H), 7.80 (d, J = 10.8 Hz, 1H), 7.27 - 7.14 (m, 7H), 6.53 (s, 1H), 5.59 - 5.51 (m, 1H), 5.44 - 5.39 (m, 2H), 5.20 - 5.07 (m, 2H), 4.56 - 4.44 (m, 3H), 3.92 (s, 3H), 3.80 - 3.68 (m, 5H), 3.41 (s, 1H), 3.21 - 3.12 (m, 2H), 2.83 - 2.74 (m, 1H), 2.58 - 2.55 (m, 3H), 2.39 (s, 4H), 2.18 - 2.03 (m, 4H), 1.93 - 1.78 (m, 2H), 0.87 (t, J = 7.3 Hz, 3H). 6.2 Preparation of Antibody-Drug Conjugates Table 8 Molecular Name Antibody Cloning Adapter-Cytoxin DAR ADC-1 Zalutumumab X2 8 ADC-2 hu3F8 clone 2 X2 8 ADC-3 Cetuximab X2 8 ADC-4DBXT001-01 X2 4 ADC-5 DBXT001-01 X2 6 ADC-6 DBXT001-01 X2 8 ADC-7 DBXT001-01 XI 4 ADC-8 DBXT001-01 XI 6 ADC-9 DBXT001-01 XI 8 ADC-10 SI-1X6.4 X2 8 ADC-11 Isotype IgG1 X2 8 ADC-12 Isotype IgG1 XI 8 ADC-13 DBXT005-01 X2 6 ADC-14 SI-1X6.4 Ed-04 8 Isotype IgG1 Source: Purchased from Baiying Biotechnology (Taicang). Preparation of DBXT001-01-X1: DBXT-001-01 NH ADC-7 (DBXT001-01-X1-DAR4) was prepared by adding 10 mM EDTA solution (0.875 mL) and prepared tris(2-phenylethyl)phosphohydrochloride solution (3.48 mM, 0.379 mL, 1.32 μM 0.1) to the buffer (PBS pH 7.2; 70 mg, 8.52 mg / mL, 0.47 μmol) of antibody DBXT001-01. The mixture was placed in a 49°C constant temperature stirrer at 60 rpm and reacted at 22°C for 2 hours, after which the reaction was stopped. XI (2.61 mg, 2.43 μmol) was dissolved in 1.75 mL of EDTA solution. Add mL of DMA to the above solution, place in a constant temperature stirrer, stir at 60 rpm, and oscillate at 22°C for 2 hours. Stop the reaction. After filtration with activated carbon, the reaction solution is desalted and purified on AKTA using a G-25 gel column (desalting column: HiPrep 26 / 10 Desalting column, 53 mL; elution phase: 30 mM histidine-hydrochloric acid pH 5.5), and then concentrated by ultrafiltration with a 30 KD ultrafiltration tube to obtain a solution of the exemplary product ADC-7 (30 mM histidine-hydrochloric acid pH 5.5; 68 mg, 22 mg / mL, yield: 97%), and stored at -8°C. HIC DAR analysis detected and calculated the DAR value n = 4.06; the purity of the SEC main peak was 98.2%. ADC-8 (DBXT001-01-X1-DAR6) was added to the buffer (PBS pH 7.2) of antibody DBXT001-01. 70 mg, 8.52 mg / mL, 0.47 μmol) were added to 10 mM EDTA solution (0.875 mL) and the prepared tris(2-methylcarboethyl)phosphohydrochloride solution (3.48 mM).0.598 mL (2.08 μmol) was placed in a thermostatic stirrer at 60 rpm and heated to 22°C. (2) The reaction was stopped after 2 hours of shaking. WX1 (4.30 mg, 4.00 μmol) was dissolved in 1.75 mL of DMA and added to the above solution. The mixture was placed in a constant temperature stirrer at 60 rpm and stirred at 22°C. (2) The reaction was stopped after 2 hours of shaking. After filtration with activated carbon, the reaction solution was desalted and purified on an AKTA using a G-25 gel column (desalting column: HiPrep 26 / 10 Desalting column, 53 mL; eluent: 30 mM histidine-hydrochloric acid pH 5.5). The solution was then concentrated by ultrafiltration using a 30 KD ultrafiltration tube to obtain a solution of the exemplary product ADC-8 (30 mM histidine-hydrochloric acid pH 5.5; 69 mg, 23 mg / mL, yield: 99%). ADC-8 (TC) was stored. HIC DAR analysis was performed and the DAR value was calculated to be n = 6.11. The purity of the SEC main peak was 99.2%. (DBXT001-01-X1-DAR8) To the buffer solution of antibody DBXT001-01 (PBS pH 7.2; 70 mg, 8.52 mg / mL, 0.47 μmol), add 10 mM EDTA solution (0.875 mL) and prepared tris(2-hydroxyethyl)phosphohydrochloride solution (3.48 mM, 1.12 mL, 3.89 μmol). Place the solution in a constant temperature stirrer at 60 rpm and react at 22°C for 2 hours, then stop the reaction. Dissolve XI (5.05 mg, 4.70 μmol) in 1.75 mL DMA and add it to the above solution. Place the solution in a constant temperature stirrer at 60 rpm and react at 22°C for 2 hours, then stop the reaction. After activated carbon filtration, purify the reaction solution by desalting on an AKTA column using a G-25 gel column (desalting column: HiPrep). 26 / 10 Desalting column, 53 mL; elution phase: 30 mM histidine-hydrochloric acid pH 5.5), and after ultrafiltration and concentration with a 30KD ultrafiltration tube to obtain a solution of the exemplary product ADC-9 (30 mM histidine-hydrochloric acid pH 5.5; 68 mg, 22.4 mg / mL, yield: 97%), stored at -80. (2. HIC DAR analysis detected and calculated the DAR value n = 7.99; SEC main peak purity was 99.0% C DBXT001-01-X2 preparation 50 WO 2025 / 016453 PCT / CN2024 / 106435 ADC-4 (DBXTOO1-01-X2-DAR4) to antibody DBXT001-01 buffer (PBS pH 7.4; 70 mg, 68 mg, 22.4 mg / mL, yield: 97%), stored at -80. (2. HIC DAR analysis detected and calculated the DAR value n = 7.99; SEC main peak purity was 99.0% C DBXT001-01-X2 preparation 50 WO 2025 / 016453 PCT / CN2024 / 106435 ADC-4 (DBXTOO1-01-X2-DAR4) to antibody DBXT001-01 buffer (PBS pH 7.4; 70 mg, 68 mg, 22.4 mg / mL, yield: 97%), stored at -80.Add 8.52 mg / mL, 0.47 μmol) to 10 mM EDTA solution (0.875 mL) and prepared tris(2-ethylhexyl)phosphohydrochloride solution (3.48 mM, 0.379 mL, 1.32 μmol), place in a constant temperature stirrer, stir at 60 rpm, react at 37 °C for 2 hours, and then stop the reaction; dissolve X2 (2.75 mg, 2.59 μmol) in 1.75 mL DMA, add to the above solution, place in a constant temperature stirrer, stir at 60 rpm, and react at 22 °C. (2. Shake the reaction for 2 hours, then stop the reaction. After filtration with activated carbon, the reaction solution was desalted and purified on AKTA using a G-25 gel column (desalting column: HiPrep 26 / 10 Desalting column, 53 mL; elution phase: 30 mM histidine-hydrochloric acid, pH 5.5), and then concentrated by ultrafiltration using a 30KD ultrafiltration tube to obtain a solution of the exemplary product ADC-4 (30 mM histidine-hydrochloric acid, pH 5.5; 67.2 mg, 22 mg / mL, yield: 96%), which was stored at -8 (TC). HIC DAR analysis was performed and the DAR value was calculated to be n = 4.10; the purity of the SEC main peak was 98.4%. ADC-5 (DBXTOO 1-01-X2-DAR6) was prepared by adding 10 mM EDTA to the buffer of antibody DBXT001-01 (PBS, pH 7.4; 70 mg, 8.52 mg / mL, 0.47 μmol). The solution (0.875 mL) and the prepared tris(2-trimethylethyl)phosphohydrochloride solution (3.48 mM, 0.598 mL, 2.08 pmol) were placed in a constant temperature stirrer at 60 rpm and reacted at 37°C for 2 hours, and then the reaction was stopped. X2 (4.58 mg, 4.31 μmol) was dissolved in 1.75 mL of DMA and added to the above solution. The mixture was placed in a constant temperature stirrer at 60 rpm and reacted at 22°C for 2 hours, and then the reaction was stopped. After filtration through activated carbon, the reaction solution was desalted and purified on an AKTA using a G-25 gel column (desalting column: HiPrep 26 / 10 Desalting column, 3 mL; elution phase: 30 mM histidine-hydrochloric acid, pH 5.5), and then concentrated by ultrafiltration using a 30 KD ultrafiltration tube to obtain a solution of the exemplary product ADC-5 (30 mM histidine-hydrochloric acid, pH 5.5). 66.5 mg (25 mg / mL, yield: 95%), stored at -8°C. HIC DAR analysis was performed, and the DAR value was calculated to be n = 6.05; the purity of the SEC main peak was 98.9%. ADC-6 (DBXTOO 1-01-X2-DAR8) was added to antibody DBXT001-01.Add 10 mM EDTA solution (0.875 mL) and prepared tris(2-vinylethyl) phosphate hydrochloride solution (3.48 mM, 1.12 mL, 3.89 mol) to the buffer solution (PBS pH 7.2; 70 mg, 8.52 mg / mL, 0.47 μmol), and place in a constant temperature stirrer at 60 rpm for 2 hours at 22°C, then stop the reaction. Dissolve X2 (5.49 mg, 5.17 pmol) in 1.75 mL DMA, add to the above solution, and place in a constant temperature stirrer at 60 rpm for 2 hours at 22°C. (3. Shake the reaction for 2 hours, then stop the reaction. After filtration with activated carbon, the reaction solution was desalted and purified on an AKTA using a G-51 WO 2025 / 016453 PCT / CN2024 / 106435 25 gel column (desalting column: HiPrep 26 / 10 Desalting column, 53 mL; elution phase: 30 mM histidine-hydrochloric acid pH 5.5), and then concentrated by ultrafiltration with a 30KD ultrafiltration tube to obtain a solution of the exemplary product ADC-6 (30 mM histidine-hydrochloric acid pH 5.5; 67.9 mg, 29.2 mg / mL, yield: 97%), stored at -80°C. (2. HIC DAR analysis detected and calculated the DAR value n = 7.98; the purity of the SEC main peak was 99.0%. ADC-13 (DBXT005-01-X2, DAR6) was in PBS 7.4 buffer (PBS 7.4, 2 mM EDTA (pH 7.4) was used to reduce antibody DBXT005-01 with 20 equivalents of tris(2-ethylhexyl)phosphine (TCEP). The reaction was carried out on a shaker at 22 °C for 3 hours (shaking speed 60 rpm). After intermediate monitoring, 5 equivalents of tris(2-ethylhexyl)phosphine (TCEP) were added, and the reaction was continued on a shaker at 22 °C for 1 hour. Excess TCEP was not removed, and the reaction solution was used directly for the next coupling reaction. The reduced antibody was then slowly added at room temperature with 200 mM histidine-hydrochloric acid (pH 6.0) to achieve a final concentration of 20 mM histidine-hydrochloric acid in the coupling reaction solution. A solution containing 0.1% v / v acetic acid in dimethyl methoxide and a linker-payload solution (10 equivalents, 10 mM x 10 mM x 2 solution) was also added. Dimethyl dimethyl ether (DMSO) of v / v acetic acid was added. After thorough mixing, the coupling reaction solution was reacted on a shaker at 22°C (shaking speed 60 rpm) for 1.5 hours. After intermediate monitoring, a linker-cytotoxin (2 equivalents, 10 mM x 2 solution containing 0.1% v / v acetic acid) was added.After the dimethyl thiosulfate is thoroughly mixed, the coupling reaction solution is placed on a shaker at 22°C. (3. Continue shaking reaction for 2 hours (shaking speed 60 rpm). After the reaction, replace the ADC solution with a desalting column (40 K) to the storage buffer (20 mM histidine-hydrochloric acid, pH 6.0). Take samples for testing to obtain the ADC product. The test results are as follows: The preparation of ADC-14 (BL-B01D1, DAR8) is as follows, referring to patent WO2023083381A1: In PBS7.4 buffer (PBS7.4, 2 mM EDTA, pH 7.4), reduce antibody SI-1X6.4 with 15 equivalents of tris(2-ethylhexyl)phosphine (TCEP), and shake on a shaker at 22 °C for 17.5 hours (shaking speed 60 rpm). Do not remove excess TCEP, and use the reaction solution directly for the next coupling reaction. The reduced antibody is slowly added to dimethyl methoxide (DMSO) and linker-cytotoxic agent (Linker-payload) at room temperature.) (10 mM Ed-04 DMSO solution). The reaction system contains 10% v / v dimethyl sulfoxide (DMSO). After thorough mixing, the coupling reaction solution is incubated on a shaker at 22°C (2 rpm) for 2 hours. After interim monitoring, the linker-cytotoxin (Linkei-payload) (2 mM Ed-04 DMSO solution) is added. After thorough mixing, the coupling reaction solution is incubated on a shaker at 22°C (2 rpm) for 1.5 hours. After the reaction is complete, 200 mM histidine-hydrochloric acid, pH 5.5, is added to the reaction solution to make the histidine-hydrochloric acid concentration in the reaction solution 20 mM. The reaction solution is then filtered through a 0.22 μl PES pinhole filter, and the ADC solution is then exchanged for storage buffer (20 mM) using an AKTA desalting column (HiPrep™ 26 / 10 Desalting). Histidine-hydrochloric acid, pH 5.5). The reaction solution was concentrated using Amicon (30K MWCO), and finally filtered through a 0.22 pm PES pinhole filter to obtain the ADC product. Samples were sent for testing. Name DAR value (mass spectrometry detection) SEC aggregation degree (%) Free small molecules (mol%) Endotoxin (EU / mg) ADC-13 5.99 2.39 <2.02% <0.400 52 WO 2025 / 016453 PCT / CN2024 / 106435 Refer to the preparation process of DBXT001-01-X2, only replace the corresponding antibody clones in Table 8 to prepare ADC-1~3, ADC-10 and ADC-11o. Refer to the above experimental process, replace antibody clone DBXT001-01 in Table 8 with DBXT001-02-08.DBXT003-O1-O8 and DBXT004-01-08 can be used to prepare corresponding bispecific antibody-drug conjugates. The detection results are as follows: Name DAR value (mass spectrometry detection) SEC aggregation degree (%) Free small molecules (mol%) Endotoxin (EU / mg) ADC-14 8 1.73 <0.97% <0.208 Example 7: Evaluation of the efficacy of antibody-drug conjugates in OE-19 tumor-bearing mice with low EGFR expression and HER3 expression. To study the inhibitory effect of ADC-6 on tumor formation in human esophageal cancer cells in vivo, the anti-tumor effect of ADC-6 was evaluated after subcutaneous ectopic inoculation of OE-19 to form xenografts in mice, and compared with the anti-tumor effect of the parent monoclonal antibody ADC. 1. Test Drugs and Materials: Blank Control Group (Control Group): Physiological saline; ADC-1 (Treatment Group): Day 0: 1 mg / kg; Day 12: 3 mg / kg; ADC-2 (Treatment Group): Day 0: 1 mg / kg; Day 12: 3 mg / kg; ADC-6 (Treatment Group): Day 0: 1 mg / kg; Day 12: 3 mg / kg. 2. Preparation Method: All samples were diluted with physiological saline. 3. Experimental Animals: 6-7 week old female BALB / cNude mice, purchased from Jicui Pharmaceutical Technology Co., Ltd. 4. Experimental Method: OE-19 (CL-00806) cells were cultured in RPMI 1640 medium containing 10% fetal bovine serum and 2 mM L-Glutamine. OE-19 cells in the exponential growth phase were collected and resuspended in PBS to a suitable concentration for subcutaneous tumor inoculation in mice. 5 x 10⁶ OE-19 cells were subcutaneously inoculated into the right back of experimental mice. The cells were resuspended in a 1:1 mixture of PBS and matrix gel (0.1 mL / mouse), and tumor growth was observed periodically. When the tumor grew to approximately 140.15 m², the tumor-bearing mice were randomly assigned to studyDirector™ groups and injected with the test compound intravenously (TV) on day 0 and again on day 12, for a total of two injections. The treatment group received 1 mg / kg on day 0 and 3 mg / kg on day 12. The endpoint of the experiment was day 25 after grouping. Tumor volume and body weight were measured twice a week, and the data were recorded. Each control or treatment group consisted of 5 mice. The tumor inhibition rate was calculated by measuring tumor volume. The formula for calculating tumor volume is: N = a x bz, where 0 and 6 represent the major and minor diameters of the tumor, respectively. The tumor-inhibiting efficacy of the compound was evaluated using the T / C (%). The T / C (%) percentage is an indicator of tumor growth inhibition, where t and C represent the average tumor volume on a given day in the treatment group and control group, respectively. The tumor growth inhibition rate is calculated using the following formula: TGI (%) =[l-(TrTo) / (Vi-Vo)] x 53 WO 2025 / 016453 PCT / CN2024 / 106435 100, where T is the average tumor volume of a certain treatment group on a certain day, To is the average tumor volume of this treatment group at the start of administration; % is the average tumor volume of the solvent control group on a certain day (same as 1), and V is the average tumor volume of the solvent control group at the start of administration. Independent samples t-test (T-Test) was used to compare the two groups. Data were analyzed using SPSS, and P < 0.05 was considered statistically significant. GraphPad Prism was used for plotting. Table 9. Evaluation of the antitumor efficacy of the test drugs in the OE-19 cell subcutaneous xenograft tumor model (calculated based on tumor volume 25 days after administration) 1. Tumor volume is expressed as mean ± standard error; 2. Tumor growth inhibition is reflected by T / C (T / C(%) = T25 / V25X100)TGI (TGI (%) = [1 -(T25-T0) / (V25-V0)] χ 100); The experimental results are shown in Figure 6 and Table 9. In the OE-19 model, monoclonal antibody ADC-1 (EGFR-ADC) could not inhibit tumor growth, while bispecific antibody ADC-6 (EGFR-HER3ADC) showed better antitumor effects than monoclonal antibody ADC-2 (HER3-ADC). Experimental conclusion: In models resistant to EGFR-ADC, bispecific antibody ADCs have better antitumor effects than monoclonal antibody ADCs. Tumor volume (mn?) 1 T / C (%) 2 TGI (%) 2 Blank control group 2193.72 ±468.29 - - ADC-1 1978.95 ±332.17 90.21 9.79 ADC-2 1267.10±413.32 57.76 42.24 ADC-6 902.53 ±567.80 41.14 58.86 Example 8: Evaluation of the efficacy of antibody-drug conjugate against human non-small cell lung cancer cell line NCI-H441 expressed in EGFR and HER3 in tumor-bearing mice In order to study the inhibitory effect of ADC-6 on tumor formation of human non-small cell lung cancer cell line in vivo, after subcutaneous ectopic inoculation of NCI-H441 in mice to form xenografts, the anti-tumor effect of ADC-6 was evaluated and compared with the anti-tumor effect of the parent monoclonal antibody ADC. 1. Test drugs and materials: Blank control group (control group): physiological saline; ADC-1 (treatment group): 0.5 mg / kg; ADC-2 (treatment group): 0.5 mg / kg; ADC-6 (treatment group): 0.5 mg / kg. 2. Preparation method: All samples were diluted with physiological saline. 3. Experimental animals: 6-7 week old male NU / NU mice, purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd.4. Experimental Methods: NCI-H441 (CL-00759) cells were cultured in RPMH640 medium containing 10% fetal bovine serum. NC1-H441 cells in the exponential growth phase were collected and resuspended in PBS to a suitable concentration for subcutaneous tumor inoculation in mice. 5 x 10⁶ NCI-H441 cells were subcutaneously inoculated into the right back of each mouse, and the cells were resuspended in a 1:1 mixture of PBS and matrix gel (0.1 mL / mouse). Tumor growth was observed periodically. When the tumor grew to approximately 139.12 mm², the tumor-bearing mice were randomly assigned to StudyDirector™ groups and administered the test substance intravenously (iv) starting on day 0 (day 0), for a total of one injection. The treatment group received a dose of 0.5 mg / kg on the day of treatment. The endpoint was day 35 after grouping. Tumor volume and body weight were measured twice weekly, and data were recorded. Five mice were used in each of the control and treatment groups. Tumor inhibition rate was calculated by measuring tumor volume. The formula for calculating tumor volume was: V = 0.54 × b², where 4 and 6 represent the long and short diameters of the tumor, respectively. The tumor-inhibiting efficacy of the compound was evaluated using the T / C (%). The percentage value of T / C (%) is an indicator reflecting tumor growth inhibition, where T and C represent the average tumor volume of the treatment group and the control group on a given day, respectively. The tumor growth inhibition rate was calculated using the following formula: TGI (%) = [1 - (T. - To) / (Vi - Vo)] × 100, where t1 is the average tumor volume of the treatment group on a given day, To is the average tumor volume of the treatment group at the start of administration; Vi is the average tumor volume of the solvent control group on a given day (the same day as Ti), and Vo is the average tumor volume of the solvent control group at the start of administration. Independent samples t-tests (T-Tests) were used to compare the two groups. Data were analyzed using SPSS, and P < 0.05 was considered statistically significant. The graphing software used was GraphPad Prism. Table 10. Evaluation of the antitumor efficacy of the test substance on the NCI-H441 cell subcutaneous xenograft tumor model (calculated based on tumor volume 35 days after administration) 1. Tumor volume is expressed as mean ± standard error; 2. Tumor growth inhibition is calculated by T / C (T / C(%) = T35 / V35X100) and TGI (TGI(%) = [1-(T35-T0) / (V35-V0)] χ 100) Group Tumor volume T / C (%)2 TGI (%)2 Value 3 Blank control group, 1355.83 ±228.07 - - - ADC-1 218.89 ±33.69 16.14 83.86 * ADC-2 341.42 ±83.18 25.18 74.82 ns ADC-6 152.85±65.97 11.27 88.73 *** Reflect; The 3.0 value is calculated based on tumor volume, representing p < Q.O5, ** represents p < Q.Ql, *** represents p < Q.001, ns represents no significant meaning). The experimental results are shown in Figure 7 and Table 10. In the NCI-H441 model, ADC-6 has a better tumor inhibitory effect than ADC-2. Experimental conclusion: In models with comparable EGFR and HER3 expression levels, bispecific antibody ADC has a better tumor inhibitory effect than monospecific antibody ADC. Example 9: Pharmacodynamic evaluation of antibody-drug conjugate in tumor-bearing mice of human oral squamous cell carcinoma cell line CAL-27 with high EGFR expression and low HER3 expression To study the inhibitory effect of ADC-6 on the formation of tumors in human oral squamous cell carcinoma cell line in vivo, after subcutaneous ectopic inoculation of CAL-27 to form transplanted tumors in mice, the anti-tumor effect of ADC-6 was evaluated and compared with the anti-tumor effects of the parental monospecific antibody ADC and EGFR monoclonal antibody. 1. Test drugs and materials Blank control group (control group): Normal saline ADC-1 (treatment group): 3 mg / kg ADC-2 (treatment group): 3 mg / kg 55 WO 2025 / 016453 PCT / CN2024 / 106435 ADC-6 (treatment group): 3 mg / kg EGFR monoclonal antibody Zalutumumab (treatment group): 3 mg / kg 2. Preparation method: All samples were diluted and prepared with normal saline. 3. Test animals: Female NOD / Scid mice at 6-7 weeks of age, purchased from Jicui Pharmaceutical Biotechnology Co., Ltd. 4. Test method: CAL-27 (CL-00599) cells were cultured in DMEM medium containing 10% fetal bovine serum. CAL-27 cells in the exponential growth phase were collected and resuspended in PBS at a suitable concentration for subcutaneous tumor inoculation in mice. Experimental mice were subcutaneously inoculated with 1×10⁷ CAL-27 cells on the right dorsal side, and the cells were resuspended in a 1:1 mixture of PBS and Matrigel (0.1 mL / mouse), and the tumor growth was observed regularly. When the tumor grew to about 144.75 mm³, the tumor-bearing mice were randomly grouped by StudyDirectorTM, and on the same day (day 0), the test substances were injected intravenously (i.v.), once on the same day and once on day 14, for a total of 2 injections, and the dose of the treatment group was 3 mg / kg. The end point of the test was day 27 after grouping, and the tumor volume and body weight were measured twice a week, and the data were recorded. There were 5 mice in each group of the control group or treatment group. The tumor inhibition rate was calculated by measuring the tumor volume. The formula for calculating the tumor volume is: V = 0.5 × a × b², where a and b represent the long diameter and short diameter of the tumor, respectively. The anti-tumor efficacy of the compound was evaluated by T / C (%). The percentage value of T / C (%) is an index reflecting tumor growth inhibition, and T and C represent the treatment group andThe mean tumor volume of the control group on a given day was used. The tumor growth inhibition rate was calculated using the following formula: TGI (%) = [1 - (T1 - To) / (Vi - Vo)] × 100, where t1 is the mean tumor volume of the drug-treated group on a given day, To is the mean tumor volume of this drug-treated group at the start of administration; Vi is the mean tumor volume of the solvent control group on a given day (the same day as Ti), and Vo is the mean tumor volume of the solvent control group at the start of administration. Independent samples t-tests (T-Tests) were used to compare the two groups. Data were analyzed using SPSS, with P < 0.05 considered statistically significant. GraphPad Prism was used for plotting. Table 11. Evaluation of the antitumor efficacy of the test substances in the CAL-27 cell subcutaneous xenograft tumor model (calculated based on tumor volume 27 days after administration) 1. Tumor volume is expressed as mean ± standard error; 2. Tumor growth inhibition is reflected by T / C (T / C(%) = T27 / V27×100) and TGI (TGI(%) = [1 -(T27-T0) / (V27-V0)]×100); 3. 0 values ​​calculated based on tumor volume represent P<0.05, ** represents pv0.01, *** represents pv0.001, ns represents no significant difference). The experimental results are shown in Figure 8 and Table 1. In the CAL-27 model, ADC-1 and ADC-6 both showed significant antitumor effects, and were superior to ADC-2 and EGFR monoclonal antibodies. Group Tumor Volume T / C (%)2 TGI (%)2 O Value 3 Blank Control Group 1193.68 ±152.76 - - - ADC-1 63.57 ± 10.46 5.33 94.67 *** ADC-2 1171.19±213.03 98.12 1.88 ns ADC-6 158.74 ±68.86 13.30 86.70 *** EGFR Monoclonal Antibody 689.00 ±235.58 57.72 42.28 ns 56 WO 2025 / 016453 PCT / CN2024 / 106435 Experimental Conclusion: In the EGFR-sensitive, EGFR-high expression, HER3-low expression model, bispecific antibody ADC is superior to EGFR monoclonal antibody or HER3 ADCs exhibit superior tumor-suppressing effects and are not inferior to EGFR ADCs. Example 10: Evaluation of the efficacy of antibody-drug conjugates with different DAR values ​​in NCI-H1975 and OE-19 tumor-bearing mice. To study the inhibitory effect of different DAR values ​​of the DBXTOO1-01 conjugate-cytotoxin X2 on tumor formation in human non-small cell lung cancer cell line NCLH1975 and human esophageal cancer cell line OE-19, NCI-H1975 cells were ectopically inoculated subcutaneously on the right back of mice.Alternatively, after OE-19 forms a xenograft, the antitumor effect of dual anti-drug conjugates with different DAR values ​​can be evaluated. The investigational drugs and dosing regimens are shown in Tables 12 and 13. Table 12. Administration Route, Dosage, and Regimen in the Human Lung Cancer NCLH1975 Subcutaneous Xenograft Model Group | Number of Animals | Dosage (mg / kg) | Administration Route | Dosage Cycle | 1 | 5 | Blank Control Group | - | iv Q2Wx2 | 2 | 5 | ADC-2 | 10 | iv Q2Wx3 | 3 | 5 | ADC-4 | 3 | iv Q2Wx2 | 4 | 5 | ADC-5 | 3 | iv Q2Wx3 | 5 | 5 | ADC-6 | 3 | iv Q2Wx3 Table 13. Administration Route, Dosage, and Regimen in the Human Esophageal Cancer OE-19 Cell Line Subcutaneous Xenograft Model | Group | Number of Animals | Dosage (mg / kg) | Administration Route | Dosage Cycle | 1 | 5 | Blank Control Group | - | iv Q2Wx2 | 2 | 5 | ADC-1 | 6 | iv Q2Wx2 | 3 | 5 | ADC-2 | 6 | iv Q2Wx2 | 4 | 5 | ADC-4 | 6 | iv Q2Wx2 | 5 | 5 ADC-5 6 iv Q2Wx 2 6 5 ADC-6 6 iv Q2Wx 2 2. Preparation method: All samples were diluted with physiological saline. 3. Experimental animals: 6-8 week old female Balb / c nude mice, purchased from Jicui Pharmaceutical Technology Co., Ltd. 4. Experimental methods: NCI-H1975 (CL-00650) cells were cultured in RPMI1640 medium containing 10% fetal bovine serum, and OE-19 (CL-00806) cells were cultured in RPMI1640 medium containing 10% fetal bovine serum and 2 mM L-Glutamine. Cells in the exponential growth phase were collected and resuspended in PBS to a suitable concentration for subcutaneous tumor inoculation in nude mice. 5 x 10⁶ ncI-H1975 cells were subcutaneously inoculated into the right back of the experimental mice, and the cells were resuspended in PBS (0.1 mL / mouse). Tumor growth was observed regularly. Experimental mice were subcutaneously inoculated with 5 x 10⁶ OE-19 cells on their right back. The cells were resuspended in a 1:1 mixture of PBS and matrix gel (0 mL / mouse), and tumor growth was observed periodically. When the tumor grew to approximately 2.71 mm³ (NCI-H1975) or 139.93 mm³ (OE-19), the tumor-bearing mice were randomly assigned to StudyDirector™ groups. The day of grouping was designated as Day 0. Specific drug administration regimens are shown in Tables 12 and 13. The endpoint of the experiment was 57 minutes. (WO 2025 / 016453 PCT / CN2024 / 106435)On day 31 (NCI-H1975) or day 35 (OE-19) after treatment, tumor volume and body weight were measured twice weekly and data were recorded. Five mice were in each control or treatment group. The tumor inhibition rate was calculated by measuring tumor volume. The formula for calculating tumor volume was: V = 0.5ax / A0, where A0 and A6 represent the long and short diameters of the tumor, respectively. The tumor-inhibiting efficacy of the compound was evaluated using T / C (%). The percentage value of T / C (%) is an indicator reflecting tumor growth inhibition, where t and C represent the average tumor volume of the treatment group and the control group on a given day, respectively. The tumor growth inhibition rate was calculated using the following formula: TGI (%) = [1-(Ti-To) / (Vi-Vo)] x 100, where Ti is the average tumor volume of the treatment group on a given day, To is the average tumor volume of the treatment group at the start of treatment; % is the average tumor volume of the solvent control group on a given day (the same day as T), and V is the average tumor volume of the solvent control group at the start of treatment. Independent samples t-test (T-test) was used to compare the two groups of samples. Data were analyzed using SPSS, and p < 0.05 was considered statistically significant. GraphPad Prism was used for graphing. Table 14. Evaluation of the antitumor efficacy of the test substances against the NCI-H1975 cell subcutaneous xenograft tumor model (calculated based on tumor volume 18 days after administration) Group Tumor volume (nm?) t / C (%) 3 TGI (%) 3 p value 4 Blank control group 3138.18 ±34.92 - - - ADC-2 1007.29 ± 132.59 32.10 67.90 *** ADC-4 1331.77 ± 150.56 42.44 57.56 * ADC-5 243.30 ±80.55 7.75 92.25 *** ADC-6 212.18 ± 106.87 6.76 93.24 *** Table 15. Evaluation of the antitumor efficacy of the test substances against a subcutaneous xenograft tumor model of OE-19 cells (calculated based on tumor volume 21 days after administration) Group | Tumor Volume (mil) | t / C (%) | TGI (%) | P-value | Blank Control Group | 1734.6±617.12 | - | - | - ADC-1 | 1078.01 ±263.36 | 62.15 | 37.85 ns ADC-2 | 741.6 ± 195.8 | 42.75 | 57.25 ns ADC-4 | 595.89 ± 141.93 | 34.35 | 65.65 ns ADC-5 | 744.13 ±229.18 | 42.90 | 57.10 ns ADC-6 | 305.00 ±56.98 | 17.58 | 82.42 * 11. Because some mice in the NCI-H1975 blank control group reached the euthanasia criteria after 18 days, the statistical analysis data was incomplete. Therefore, the statistical analysis was performed on day 18 when the number of animals was complete. Similarly, in the OE-19 blank control group, some mice reached the euthanasia criteria after 21 days, and the statistical analysis data was incomplete. Therefore, the statistical analysis was performed on day 21 when the number of animals was complete. 2. Tumor volume is expressed as mean ± standard error. 3. Tumor growth inhibition is reflected by T / C (T / C(%) = TD / VD x 100) ⇌ TGI (TGI (%) = [1-(TD-TO) / (VD-V0)] x 100). 4. p-values ​​are calculated based on tumor volume (*^p<0.05, ** represents p<0.01, ^^p<0.001, ns represents no significant difference). Brain experiment results are shown in Figures 9 and 10 and Tables 14 and 15. In the NCI-H1975 model dosing regimen, ADC-2, ADC-4, ADC-5, and ADC-6 all exhibit tumor-inhibiting effects. Experimental conclusion: The bispecific antibody-drug conjugate of this invention, targeting EGFR and HER3, with a cytotoxic agent X2, has an antitumor effect, and this effect increases with increasing DAR value. Example 11: Comparison of the efficacy of this antibody-drug conjugate and the control antibody-drug conjugate in NCI-H1975 tumor-bearing mice. This comparison examines the inhibitory effects of DBXT001-01 conjugate with cytotoxic agent X2 and the control antibody SI-1X6.4 conjugate with cytotoxic agent X2 on tumor formation in human non-small cell lung cancer cell line NCI-H1975. The antitumor effects of both conjugates were evaluated after subcutaneous ectopic inoculation of NCI-H1975 cells into the right back of mice to form xenografts. The test drugs and administration regimens are shown in Table 16. Table 16. Administration Routes, Dosages, and Regimens in a Human Lung Cancer NCLH1975 Subcutaneous Xenograft Model Group | Number of Animals | Dosage (mg / kg) | Administration Method | Dosage Cycle 1 | 5 | Blank Control Group | - | Intravenous Injection (single injection) 2 | 5 | ADC-3 | 3 | Intravenous Injection (single injection) 3 | 5 | ADC-6 | 3 | Intravenous Injection (single injection) 4 | 5 | ADC-10 | 4a | Intravenous Injection (single injection) a. Molar conversion was performed according to molecular weight to ensure consistent molar concentrations among treatment groups. 1. Preparation Method: All samples were diluted with physiological saline. 2. Experimental Animals: 6-8 week old female Balb / c nude mice, purchased from Jicui Pharmaceutical Technology Co., Ltd. 3. Experimental Method: NCI-H1975 (CL-00650) cells were cultured in RPMI1640 medium containing 10% fetal bovine serum. Cells in the exponential growth phase were collected and resuspended in PBS to a suitable concentration for subcutaneous tumor inoculation in nude mice.5 x 10⁶ NCI-H1975 cells were subcutaneously inoculated into the right back of experimental mice, and the cells were resuspended in 1:1 DPBS:Matrigel (0.2 mL / mouse). Tumor growth was observed regularly. When the tumor grew to approximately 164 mm³ (NCI-H1975), the tumor-bearing mice were randomly assigned to different groups using StudyDirector™, with the day of grouping designated as Day 0. The specific dosing regimen is shown in Table 16. The endpoint of the experiment was day 26 after grouping. Tumor volume and body weight were measured twice a week, and the data were recorded. There were 5 mice in each control or treatment group. The tumor inhibition rate was calculated by measuring tumor volume. The formula for calculating tumor volume is: V = 0.54 × b², where 4 and 6 represent the long and short diameters of the tumor, respectively. The tumor-inhibiting efficacy of the compound was evaluated using T / C (%). The percentage value of T / C (%) is an indicator reflecting tumor growth inhibition, where T and C represent the average tumor volume of the treatment group and the control group on a given day, respectively. Tumor growth inhibition rate was calculated using the following formula: TGI (%) = [1 - (T1 - To) / (Vi - Vo)] × 100, where t1 is the average tumor volume of a given treatment group on a specific day, To is the average tumor volume of that treatment group at the start of treatment, m is the average tumor volume of the solvent control group on a specific day (the same day as t1), and Vo is the average tumor volume of the solvent control group at the start of treatment. Independent samples t-tests (T-Tests) were used to compare the two groups. Data were analyzed using SPSS, and P < 0.05 was considered statistically significant. GraphPad Prism was used for plotting. Table 17. Evaluation of the antitumor efficacy of the test substance on the NCI-H1975 cell subcutaneous xenograft tumor model (calculated based on tumor volume at 17 days post-administration) Group | Tumor Volume (mm) | T / C (%) | TGI (%) | O value | 4 | 59 | WO | 2025 / 016453 | PCT / CN2024 / 106435 1. Because some mice in the NCI-H1975 blank control group reached the euthanasia criteria after 17 days, the statistical analysis data was incomplete. Therefore, statistical analysis was performed on the 17th day when the number of animals was complete. 2. Tumor volume is expressed as mean ± standard error. 3. Tumor growth inhibition is reflected by 17c (T / C (%) = Ti7 / Vi7 x 100) and TGI (TGI (%) = [!-(Ti7-T0) / (Vi7-V0)] x 100). 4. p-value is calculated based on tumor volume (* represents p<0.05). ** represents p < 0.01, *** represents pv 0.01, ns represents no statistical significance. The experimental results are shown in Figure 11 and Table 17. In the NCLH1975 model dosing regimen, ADC-3, ADC-6, and ADC-10 all...It has a significant tumor-suppressing effect, among which ADC-6 showed the strongest tumor-suppressing effect, while ADC-3 and ADC-10 had comparable efficacy. Experimental conclusion: The bispecific antibody conjugated with head-cytotoxin X2 (DAR8) of this invention, targeting EGFR and HER3, has a stronger tumor-suppressing effect than the control antibody SI-1X6.4 conjugated with head-cytotoxin X2 (DAR8). Blank control group 2414.60 ±288.22 - - - ADC-3 880.55 ±227.95 34.67 68.16 *** ADC-6 461.66 ± 158.24 16.73 86.82 *** ADC-10 1054.42 ± 175.66 40.51 60.45 *** Example 12: Comparison of the efficacy of this antibody-drug conjugate and the control antibody-drug conjugate in OE-19 tumor-bearing mice. The inhibitory effect of DBXT001-01 conjugate with head-cytotoxin X2 or head-cytotoxin XI on tumor formation in human esophageal cancer cell line OE-19 was compared with that of control antibody SI-1X6.4 conjugate with head-cytotoxin X2. After OE-19 was subcutaneously inoculated into the right back of mice to form xenografts, the in vivo antitumor effect was evaluated. The test drugs and dosing regimens are shown in Table 18. Table 18. Dosage routes, dosages, and regimens in a human esophageal cancer OE-19 subcutaneous xenograft model. Group | Number of Animals | Dosage (mg / kg) | Dosing Method | Dosing Cycle 1 | 5 | Blank Control Group | - | 2 | 5 | ADC-11 | 7.5 | Intravenous injection once a week for 3 weeks 3 | 5 | ADC-3 | 7.5 | Intravenous injection once a week for 3 weeks 4 | 5 | ADC-6 | 7.5 | Intravenous injection once a week for 3 weeks 5 | 5 | ADC-10 | 10a | Intravenous injection once a week for 3 weeks 6 | 5 | ADC-9 | 7.5 | Intravenous injection once a week for 3 weeks a. Molar conversion was performed according to molecular weight to ensure consistent molar concentrations among treatment groups. 1. Preparation method: All samples were diluted with physiological saline. 2. Experimental animals: 6-8 week old female Balb / c nude mice, purchased from Jicui Pharmaceutical Technology Co., Ltd. 3. Experimental Methods: OE-19 (CL-00806) cells were cultured in RPMI 1640 medium containing 10% fetal bovine serum and 2 mM L-Glutamine. 5 x 10⁸ OE-19 cells were subcutaneously inoculated into the right back of experimental mice. The cells were resuspended in a 1:1 mixture of PBS and matrix gel (0.1 mL / mouse), and tumor growth was observed periodically. When the tumor grew to approximately 138 mm³, the tumor-bearing mice were randomly assigned to StudyDirector™ groups. The day of grouping was designated Day 0.The dosing regimen is shown in Table 18. The endpoint of the trial was day 21 after grouping. Tumor volume and body weight were measured twice a week, and the data were recorded. There were 5 mice in each control or treatment group. The tumor inhibition rate was calculated by measuring tumor volume. The formula for calculating tumor volume is: V = 0.5·x / A, where · and 6 represent the long and short diameters of the tumor, respectively. The tumor inhibition efficacy of the compound was evaluated using T / C (%). The percentage value of T / C (%) is an indicator reflecting tumor growth inhibition, where T and C represent the average tumor volume of the treatment group and the control group on a certain day, respectively. The tumor growth inhibition rate was calculated using the following formula: TGI (%) = [1-(Ti-To) / (Vi-Vo)] x 100, where T is the average tumor volume of a certain treatment group on a certain day, To is the average tumor volume of the treatment group at the start of administration; % is the average tumor volume of the solvent control group on a certain day (same as 1), and Vo is the average tumor volume of the solvent control group at the start of administration. Independent samples t-test (T-Test) was used to compare the two groups of samples. Data were analyzed using SPSS, and P < 0.05 was considered statistically significant. GraphPad Prism was used for graphing. Table 19. Evaluation of the antitumor efficacy of the test substance on the OE-19 cell subcutaneous xenograft tumor model (calculated based on tumor volume 21 days after administration). 1. Tumor volume is expressed as mean ± standard error; 2. Tumor growth inhibition is reflected by T / C (T / C(%) = T2i / V2i x l00) and TGI (TGI(%) = [l - (T2i - T0) / (V2i - V0)] x l00). 3d values ​​are calculated based on tumor volume (* represents pv 0.05, ** represents pv 0.01, *** represents pvQ.QOl, ns represents no significant difference). Tumor volume (mnP) t / C (%) 2 TGI (%) 2 O value 3 Blank control group 2621.07 ±438.01 - - - ADC-11 2486.00 ±454.45 94.85 5.15 ns ADC-3 1601.60±371.78 61.10 38.90 ns ADC-6 704.78 ± 121.82 26.89 73.11 * ADC-10 1646.57 ± 368.12 62.82 37.18 ns ADC-9 1461.81 ±347.47 The experimental results (55.77 ns and 44.23 ns) are shown in Figure 12 and Table 19. In the OE-19 model dosing regimen, ADC-3, ADC-6, ADC-9, and ADC-10 all showed antitumor activity, with ADC-6 exhibiting the strongest antitumor effect. ADC-3, ADC-9, and ADC-10 had comparable efficacy. Experimental conclusion:In a model of EGFR-targeted therapy resistance, the bispecific antibody conjugate of this invention, targeting both EGFR and HER3, coupled with a cytotoxin X2 (DAR8), overcame EGFR resistance and exhibited a stronger antitumor effect than the control antibody SI-1X6.4 coupled with a cytotoxin X2 (DAR8). Example 13: Efficacy evaluation of the antibody-drug conjugate coupled with a cytotoxin X1 (DAR8) in NCI-H1975 tumor-bearing mice. To study the inhibitory effect of DBXT001-01 coupled with a cytotoxin X1 (DAR8) on tumor formation in the human non-small cell lung cancer cell line NCI-H1975, the antitumor effect of this antibody conjugate was evaluated after subcutaneous ectopic inoculation of NCI-H1975 cells on the right back of mice to form xenografts. 61 WO 2025 / 016453 PCT / CN2024 / 106435 Table 20. Administration routes, dosages, and regimens in the human lung cancer NCI-H1975 subcutaneous xenograft model. The test drugs and administration regimens are shown in Table 20. Group Number of animals Dosage group Dosage (mg / kg) Administration route Administration cycle 1 5 Blank control group - iv QW*4 2 5 ADC-12 7.5 iv QWx4 3 5 ADC-9 7.5 iv QW><4 2. Preparation method: All samples were diluted with physiological saline. 3. Experimental Animals: NCI-H1975: 6-8 week old female CB-17SCID, purchased from Beijing Vital River Laboratory Animal Technology Co., Ltd.; 4. Experimental Methods: NCI-H1975 (Chinese Academy of Sciences Cell Bank) cells were cultured in RPMI 1640 medium containing 10% fetal bovine serum. Cells in the exponential growth phase were collected and resuspended in DPBS to a suitable concentration for subcutaneous tumor inoculation in nude mice. 5 x 10⁶ n NCI-H1975 cells were subcutaneously inoculated into the right back of experimental mice (resuspended cells in DPBS 1:1 mixed with BDMatrigel matrix gel, Catalogue: 356234, 0.2 mL / mouse). Tumor growth was observed regularly. When the tumor grew to approximately 201.31 mm⁵, the tumor-bearing mice were randomly assigned to StudyDirector™ groups. The day of grouping was designated Day 0. Specific drug administration protocols are shown in Table 20. The experimental endpoint was day 20 after grouping. Tumor volume and body weight were measured twice weekly, and data were recorded. Five mice were used in each of the control and treatment groups. Tumor inhibition rate was calculated by measuring tumor volume. The formula for calculating tumor volume was: V = 0.54 × b², where 4 and 6 represent the long and short diameters of the tumor, respectively. The antitumor efficacy of the compound was evaluated using T / C (%). The percentage value of T / C (%) is an indicator reflecting tumor growth inhibition, where T and C represent the average tumor volume on a given day in the treatment and control groups, respectively. The tumor growth inhibition rate was calculated using the following formula: TGI (%) =[l-(T.-To) / (Vi-Vo)] χ² 100, where t1 is the mean tumor volume of a given treatment group on a specific day, To is the mean tumor volume of that treatment group at the start of treatment, m is the mean tumor volume of the solvent control group on a specific day (same as t1), and Vo is the mean tumor volume of the solvent control group at the start of treatment. Independent samples t-tests (T-Tests) were used to compare the two groups. Data were analyzed using SPSS, and P < 0.05 was considered statistically significant. GraphPad Prism was used for plotting. Table 21. Evaluation of the antitumor efficacy of the test substance on the NCI-H1975 cell subcutaneous xenograft tumor model (calculated based on tumor volume at 18 days post-administration) Group | Tumor Volume (mm²) | T / C (%) | TGI (%) | P-value | Blank Control Group | 2044.16±176.43 | - | - | - | ADC-12 | 1981.68±132.22 | 97.22 | 3.29 ns | ADC-9 | 72.36±19.18 | 3.51 | 104.42 *** 1. Because some mice in the NCI-H1975 blank control group met the euthanasia criteria after 18 days, the statistical analysis data was incomplete. Therefore, statistical analysis was performed on the 18th day when the number of animals was complete. 2. Tumor volume is expressed as mean ± standard error. 3. Tumor growth inhibition was calculated by T / C (T / C(%) = T18 / Vi8×100) and TGI (TGI(%) = [l-(Ti8-To) / (Vi8-Vo)] χ100) reflects; 62 WO 2025 / 016453 PCT / CN2024 / 106435 4. p-value is calculated based on tumor volume (* represents pv 0.05, ** represents pv 0.01, *** represents pv 0.001, ws represents no significance). The experimental results are shown in Figure 13 and Table 21. In the NCI-H1975 model dosing regimen, ADC-9 has a significant tumor-inhibiting effect, while the blank control group and ADC-12 have no tumor-inhibiting effect. Experimental conclusion: The antibody-drug conjugate of this invention, targeting EGFR and HER3 and coupled with cytotoxic XI, has a significant inhibitory effect on tumor growth. Table 22. Administration routes, dosages, and regimens in a human esophageal cancer 0E-19 subcutaneous xenograft model. Example 14: Comparison of the efficacy of the present invention's bispecific antibody ADC and control ADC in a mouse model resistant to EGFRADCs. To compare the efficacy of DBXT005-01 ADC (ADC-13) and control ADC (BL-B01D1, ADC-14) in an EGFRADC-resistant model, the antitumor effects of the two were compared after subcutaneous ectopic inoculation of OE-19 to form xenografts in mice. 1. Test drugs and administration regimens are shown in Table 22. Group | Number of animals | Administration groupDosage (mg / kg) Administration Method Dosage Cycle 1 5 Blank Control Group - Intravenous injection (single injection) 2 5 ADC-13 5 Intravenous injection (single injection) 3 5 ADC-14 8 Intravenous injection (single injection) 2. Preparation Method: All samples were diluted with physiological saline. 3. Experimental Animals: 6-7 week old female BALB / cNude mice, purchased from Jicui Pharmaceutical Technology Co., Ltd. 4. Experimental Method: OE-19 (CL-00806) cells were cultured in RPMI 1640 medium containing 10% fetal bovine serum and 2 mL of Glutamine. OE-19 cells in the exponential growth phase were collected and resuspended in PBS to a suitable concentration for subcutaneous tumor inoculation in mice. 5 x 10⁶ OE-19 cells were subcutaneously inoculated into the right back of the experimental mice. The cells were resuspended in a 1:1 mixture of PBS and matrix gel (0.1 mL / mouse), and tumor growth was observed periodically. When the tumors grew to approximately 151 mm³, tumor-bearing mice were randomly assigned using StudyDirector™ and injected intravenously (iv) with the test substance starting on day 1 (day 1), for a total of one injection. The endpoint of the experiment was day 23 after grouping. Tumor volume and body weight were measured twice weekly, and data were recorded. Five mice were assigned to each of the control or treatment groups. The tumor inhibition rate was calculated by measuring tumor volume. The formula for calculating tumor volume is: V = 0.5ax / A0, where A0 and A6 represent the long and short diameters of the tumor, respectively. The tumor-inhibiting efficacy of the compound was evaluated using T / C (%). The percentage value of T / C (%) is an indicator reflecting tumor growth inhibition, where t and C represent the average tumor volume of the treatment group and the control group on a given day, respectively. The tumor growth inhibition rate was calculated using the following formula: TGI (%) = [1 - (Ti - To) / (Vi - Vo)] x 100, where Ti is the average tumor volume of the treatment group on a given day, To is the average tumor volume of the treatment group at the start of administration, % is the average tumor volume of the solvent control group on a given day (same as day 1), and V is the average tumor volume. The mean tumor volume at the start of administration is shown in the solvent control group. One-way comparisons between sample groups were performed, with P < 0.05 considered statistically significant. Graphing and statistical analysis were performed using GraphPad Prism. Table 23. Evaluation of the antitumor efficacy of the test substance on a subcutaneous xenograft tumor model of OE-19 cells (calculated based on tumor volume 23 days after administration). 1. Tumor volume is expressed as mean ± standard error; 2. Tumor growth inhibition is reflected by T / C (T / C(%) = T23 / V23 × 100) × TGI (TGI(%) = [1 - (T23 - To) / (V23 - Vo)] × 100).3. p-values ​​are calculated based on tumor volume, representing pv 0.05, ** represents pv 0.01, *** represents pv 0.001, and ns represents no statistical significance. Experimental results are shown in Figure 14 and Table 23. In the EGFRADC resistance model, the antibody-drug conjugate of this invention showed better tumor suppression than the control ADC-14. Group Tumor volume (mn?) i T / C (%) 2 TGI (%) 2 P value 3 Blank control group 1837.21 ±66.04 - - - ADC-13 791.04 ± 110.20 42.73 62.05 * ADC-14 1165.86± 129.79 63.41 39.83 ns Example 15 Comparison of the efficacy of the bispecific antibody ADC of the present invention and the control ADC in a mouse model with high EGFR expression and low HER3 expression To compare the inhibitory effects of DBXT005-01 ADC (ADC-13) and control ADC (BL-B01D1, ADC-14) on tumor formation in EGFR-high and HER3-low expression cell lines, the antitumor effects of the two were compared after subcutaneous ectopic inoculation of A431 to form xenografts in mice. 1. Test drugs and administration regimens are shown in Table 244. Table 24. Administration Routes, Dosages, and Regimens in a Human Skin Cancer A431 Subcutaneous Xenograft Model | Group | Number of Animals | Dosage Group | Dosage (mg / kg) | Administration Method | Dosage Cycle | |---|---|---|---|---| | 1 | 5 | Excipient / Solvent Group | - | Intravenous Injection | Single Injection | | 2 | 5 | ADC-13 | 6 | Intravenous Injection | Single Injection | | 3 | 5 | ADC-14 | 6 | Intravenous Injection | Single Injection | 2. Preparation Method: All samples were diluted with excipient / solvent. | | 3. Experimental Animals: 6-8 week old female NCG mice, purchased from Jicui Pharmaceutical Technology Co., Ltd. | | 4. Experimental Method: A431 (CRL-1555) cells were cultured in DMEM medium containing 10% fetal bovine serum and 2 mM L-Glutamine. A431 cells in the exponential growth phase were collected and resuspended in PBS to a suitable concentration for subcutaneous tumor inoculation in mice. 5 x 10⁶ A431 cells were subcutaneously inoculated into the right back of the experimental mice, and tumor growth was observed periodically. When the tumor grew to approximately 137 mm³, tumor-bearing mice were randomly assigned to groups and administered the test substance intravenously (iv) once starting on day 0. The endpoint was day 21 after grouping. Tumor volume and body weight were measured twice weekly, and data were recorded. Five mice were assigned to each control or treatment group. The tumor inhibition rate was calculated by measuring tumor volume. The formula for calculating tumor volume is: V = 0.5·x / A, where · and 6 represent the major and minor diameters of the tumor, respectively. The tumor-inhibiting efficacy of the compound was assessed using TGI.(%)evaluate. The tumor growth inhibition rate was calculated using the following formula: TGI(%) = [1 - (Ti / To) / (Vi / Vo)] × 100, where Ti is the average tumor volume of a given treatment group on a certain day, To is the average tumor volume of the given treatment group at the start of administration; m is the average tumor volume of the solvent control group on a certain day (same as Ti), and Vo is the average tumor volume of the solvent control group at the start of administration. One-way comparisons were made between sample groups, with p < 0.05 considered statistically significant. Graphing and statistical analysis were performed using GraphPad Prism. Table 25. Evaluation of the antitumor efficacy of the test substance on a subcutaneous xenograft tumor model of A431 cells (calculated based on tumor volume 21 days after administration). 1. Tumor volume is expressed as mean ± standard error; 2. Tumor growth inhibition is calculated as T / C (T / C(%) = T2i / V2i x 100) π TGI (TGI(%) = [1 - (T2i / T0) / (V2i / V0)] xlOO) reflects; 3. p value is calculated based on tumor volume, representing PV 0.05, ** represents ρv 0.01, *** represents pvQ 0.001, ns represents no significance). Comparison of tumor volume between each experimental group and the blank control group. 4M value is calculated based on tumor volume (* represents pv 0.05, ** represents ρv 0.01, *** represents pvQ 0.00, ns represents no significance). Comparison of tumor volume between the bispecific antibody ADC and control ADC experimental groups in this example. Group Tumor volume (mm3) 1 TGI (%) 2 2 value 3 2 value 4 Blank control group 3367.45±287.92 - - - ADC-13 (6 mg / kg) 799.85±75.63 76.28 ** *** ADC-14 (6 mg / kg) 2860.17±76.43 15.47 ns - The experimental results are shown in Figure 15 and Table 25. In a tumor model with high EGFR expression and low HER3 expression, at the same dosage, the antibody-drug conjugate of this invention had a better tumor-suppressing effect than the control ADC. The control ADC could not inhibit tumor growth at the same dosage concentration. Mice in each treatment group tolerated the drug well, and there was no significant decrease in body weight. Example 16 The efficacy comparison of the bispecific antibody ADC and the control ADC in a mouse model of xenograft tumors of human colon cancer cells that do not express EGFR but only express HER3 was conducted to compare the inhibitory effects of DBXT005-01 ADC (ADC-13) and the control ADC (BL-B01D1, ADC-14) on tumor formation in human colon cancer cells that do not express EGFR but only express HER3. The antitumor effects of the two were compared after subcutaneous ectopic inoculation of SW620 to form xenografts in mice. 1. The test drugs and administration regimens are shown in Table 26.Table 26. Administration Routes, Dosages, and Regimens in a Human Colon Cancer SW620 Subcutaneous Xenograft Model Group | Number of Animals | Dosage (mg / kg) | Administration Method | Dosage Cycle 1 | 5 | Excipient / Solvent Group | - | Intravenous injection once every three weeks, twice 2 | 5 | ADC-13 | 10 | Intravenous injection once every three weeks, twice 3 | 5 | ADC-14 | 10 | Intravenous injection once every three weeks, twice 6 | 5 | WO 2025 / 016453 PCT / CN2024 / 106435 2. Preparation Method: All samples were diluted with excipient / solvent. 3. Experimental Animals: 6-8 week old female NCG mice, purchased from Jicui Pharmaceutical Technology Co., Ltd. 4. Experimental Method: SW620 (CCL-227) cells were cultured in DMEM medium containing 10% fetal bovine serum and 2 mM L-Glutamine. SW620 cells in the exponential growth phase were collected and resuspended in PBS to a suitable concentration for subcutaneous tumor inoculation in mice. 5 x 10⁶ SW620 cells were subcutaneously inoculated into the right back of experimental mice, and tumor growth was observed regularly. When the tumor grew to approximately 131 mm³, the tumor-bearing mice were randomly assigned to groups, and the test substance was injected intravenously (iv) on the same day (day 0). The experimental endpoint was day 59 after grouping. Tumor volume and body weight were measured twice a week, and data were recorded. There were 5 mice in each control or treatment group. The tumor inhibition rate was calculated by measuring tumor volume. The formula for calculating tumor volume is: V = 0.54 x b², where 4 and 6 represent the long and short diameters of the tumor, respectively. The tumor-inhibiting efficacy of the compound was evaluated using TGI (%). The tumor growth inhibition rate was calculated using the following formula: TGI (%) = [1 - (Ti / To) / (Vi / Vo)] x 100, where 1 is the average tumor volume of a given treatment group on a certain day, To is the average tumor volume of this treatment group at the start of administration; % is the average tumor volume of the solvent control group on a certain day (same as 1), and Vo is the average tumor volume of the solvent control group at the start of administration. One-way analogy was used for comparisons between sample groups. P < 0.05 was considered statistically significant. Graphing software and statistical analysis were performed using GraphPad Prism. Table 27. Evaluation of the antitumor efficacy of the test drugs on the SW620 cell subcutaneous xenograft tumor model. Group Day 31 Tumor volume (mm3) 1 TGI (%) 2 P value 3 2 value 4 Day 59 Tumor volume (mm3) 1 2 value 4 Blank control group 2619.88±293.60 - - - N / A5 - ADC-13 (10mg / kg) 5.01±1.81 99.81% *** *** O.OOiO.OO *** ADC-14 (10mg / kg) 109.34±19.03 95.86% *** -958.00±79.34 - 1. Tumor volume is expressed as mean ± standard error; 2. Tumor growth inhibition is reflected by TGI (TGI (%) = [1-(Τ3ι / Τ0) / (V3I / VO)] χ100); 3. p-value is calculated based on tumor volume, representing PV ≥ 0.05, ** represents ρv ≥ 0.01, *** represents pvQ ≥ 0.001, ns represents no statistical significance). Comparison of tumor volume between each experimental group and the blank control group. 4. M value is calculated based on tumor volume (* represents pv ≥ 0.05, ** represents ρv ≥ 0.01, *** represents pvQ ≥ 0.001, ns represents no statistical significance). Comparison of tumor volume between the bispecific antibody ADC and control ADC experimental groups in this example. 5. N / A represents that the control mice were euthanized on day 31 according to animal welfare principles. The experimental results are shown in Figure 16 and Table 27. In a tumor model where EGFR is not expressed but HER3 is expressed, all experimental groups showed significant inhibition of tumor growth compared to the blank control group. At the same dosage, the antibody-drug conjugate of this invention had a better tumor-suppressing effect than the control ADC, enabling complete tumor regression that lasted until day 59. The control ADC did not induce complete tumor regression or inhibit tumor regrowth. Mice in all treatment groups tolerated the drug well, with no significant decrease in body weight. 66 WO 2025 / 016453 PCT / CN2024 / 106435 Example 17: Comparison of the efficacy of the present invention's bispecific antibody ADC and control ADC in a mouse model of xenograft tumors of human colon cancer cells with low HER3 expression in EGFR. The inhibitory effects of DBXT005-01 ADC (ADC-13) and control ADC (BL-B01D1, ADC-14) on tumor formation in human colon cancer cells with low HER3 expression in EGFR were compared. After subcutaneous ectopic inoculation of SW48 to form xenografts in mice, the antitumor effects of the two were compared. 1. Test drugs and administration regimens are shown in Table 28. Table 28. Administration Routes, Dosages, and Regimens in a Human Colon Cancer SW48 Subcutaneous Xenograft Model Group | Number of Animals | Dosage (mg / kg) | Administration Method | Dosage Cycle 1 | 5 | Excipient Solvent Group | - | Intravenous injection once every three weeks, twice 2 | 5 | ADC-13 | 10 | Intravenous injection once every three weeks, twice 3 | 5 | ADC-14 | 10 | Intravenous injection once every three weeks, twice 2. Preparation Method: All samples were diluted with excipient solvents. 3. Experimental Animals: 6-8 week old female NCG mice, purchased from Jicui Pharmaceutical Technology Co., Ltd. 4. Experimental Method: SW48 (CCL-231) cells were cultured in DMEM medium containing 10% fetal bovine serum and 2 mM L-Glutamine. CollectionSW48 cells in the exponential growth phase were resuspended in PBS to a suitable concentration for subcutaneous tumor inoculation in mice. 10⁷ SW48 cells were subcutaneously inoculated into the right back of experimental mice, and tumor growth was observed periodically. When the tumor reached approximately 131 mm³, the tumor-bearing mice were randomly assigned to groups, and the test substance was administered intravenously (iv) on day 0. The endpoint of the experiment was day 45 after grouping. Tumor volume and body weight were measured twice weekly, and data were recorded. Five mice were assigned to either the control or treatment group. The tumor inhibition rate was calculated by measuring tumor volume. The formula for calculating tumor volume was: V = 0.54 x b², where 4 and 6 represent the long and short diameters of the tumor, respectively. The tumor-inhibiting efficacy of the compound was evaluated using TGI (%). The tumor growth inhibition rate was calculated using the following formula: TGI (%) = [1 - (Ti / T()) / (Vi / Vo)] x 100, where T is the average tumor volume of a certain treatment group on a certain day, To is the average tumor volume of this treatment group at the start of administration; Y is the average tumor volume of the solvent control group on a certain day (on the same day), and Vo is the average tumor volume of the solvent control group at the start of administration. One-way ANOVA was used for comparisons between sample groups, with P < 0.05 considered statistically significant. Graphing software and statistical analysis were performed using GraphPad Prism. Table 29. Evaluation of the antitumor efficacy of the test substance on the SW48 cell subcutaneous xenograft tumor model. Group Day 21 Tumor volume (mm3) 1 TGI (%) 2 P value 3 O value 4 Day 45 Tumor volume (mm3) 1 P value 4 Blank control group 1918 13 ± 324.23 - - - N / A5 ADC-13 (10 mg / kg) 35.45±2.67 98.14 *** *** 1.44±0.94 ** * ADC-14 (10 mg / kg) 366.30±167.82 81.06 *** - 541.0H22 9.49 - 67 WO 2025 / 016453 PCT / CN2024 / 106435 1. Tumor volume is expressed as mean ± standard error; 2. Tumor growth inhibition is reflected by TGI (TGI (%) = [l-(T2i-To) / (V2i-V0)] xlOO); 3. M value is calculated based on tumor volume (* represents pOJ). 5. ** represents pvO.Ol, *** represents pvQ.OL (ns represents no statistical significance). Comparison of tumor volume between each experimental group and the blank control group. 4. The 0 value calculated based on tumor volume represents P<0.05, ** represents pv 0.01, *** represents pv 0.001, and ns represents no significant difference. This example compares the tumor volume of the bispecific antibody ADC and the control ADC experimental groups. 5.N / A represents mice in the control group that were euthanized on day 21 according to animal welfare principles. The experimental results are shown in Figure 17 and Table 29. In the tumor model with EGFR expression and low HER3 expression, all experimental groups showed significant tumor growth inhibition compared to the blank control group. At the same dosage, the antibody-drug conjugate of this invention had better tumor-suppressing effects than the control ADC, causing complete tumor regression in some mice and continuously inhibiting tumor growth until day 45. The control ADC did not cause complete tumor regression and did not inhibit tumor recurrence. Mice in all treatment groups tolerated the medication well, with no significant decrease in body weight. Example 18: A comparison of the efficacy of the bispecific anti-ADC and control ADC against osimertinib-resistant human non-small cell lung cancer cell line xenograft mouse models was conducted. The inhibitory effects of DBXT005-01 ADC (ADC-13) and the control ADC (BL-B01DL ADC-14) on tumor formation in osimertinib-resistant non-small cell lung cancer cell lines were compared. After subcutaneous ectopic inoculation of mice with NCI-H1975 (EGFR triple mutation L858R / T790M / C797S) to form xenografts, the antitumor effects of the two ADCs were compared. 1. The test drugs and administration regimens are shown in Table 30. Table 30. Administration routes, dosages, and regimens in a subcutaneous xenograft model of human non-small cell lung cancer NCI-H1975 (EGFR triple mutation L858R / T790M / C797S) | Group | Number of Animals | Dosage (mg / kg) | Administration Method | Dosage Cycle | |---|---|---|---|---| | 1 | 6 | Excipient / Solvent Group | - | Intravenous injection once every three weeks, twice | | 2 | 6 | ADC-13 | 6 | Intravenous injection once every three weeks, twice | | 3 | 6 | ADC-14 | 6 | Intravenous injection once every three weeks, twice | 2. Preparation Method: All samples were diluted with excipient / solvent. | 3. Experimental Animals: 6-7 week old female NOD / SCID mice, purchased from Jicui Pharmaceutical Technology Co., Ltd. 4. Experimental Methods: NCI-H1975 EGFR L858R / T790M / C797S (CL-01195) cells were cultured in RPMI 1640 medium containing 10% fetal bovine serum and 100 μg / mL hygromycin. NCI-H1975 cells in the exponential growth phase were collected and resuspended in PBS to a suitable concentration for subcutaneous tumor inoculation in NOD / SCID mice. Mice were subcutaneously inoculated with 1N107 Nci-H1975 EGFR L858R / T790M / C797S cells on the right back. The cells were resuspended in a 1:1 mixture of PBS and matrix gel (0.2 mL / mouse), and tumor growth was observed periodically. When the tumor reached approximately 169.46 mL, the tumor-bearing mice were randomly assigned to groups, and intravenous (iv) administration began on day 0.The test substance was injected, and the endpoint of the experiment was day 35 after grouping. Tumor volume and body weight were measured twice a week, and the data were recorded. 68 WO 2025 / 016453 PCT / CN2024 / 106435 Six mice were in each control or treatment group. The tumor inhibition rate was calculated by measuring tumor volume. The formula for calculating tumor volume was: V = 0.5 4xb², where 4 and 6 represent the long and short diameters of the tumor, respectively. The tumor-inhibiting efficacy of the compound was evaluated using TGI (%). The tumor growth inhibition rate was calculated using the following formula: TGI(%) = [l-(Ti / To) / (Vi / Vo)] X 100, where l is the average tumor volume of a given treatment group on a certain day, To is the average tumor volume of this treatment group at the start of administration; % is the average tumor volume of the solvent control group on a certain day (the same day as l), and Vo is the average tumor volume of the solvent control group at the start of administration. Comparisons between sample groups were performed using one-way analogy, with p < 0.05 considered statistically significant. The graphing software and statistical analysis were performed using GraphPad Prism. Table 31. Evaluation of the antitumor efficacy of the test substance against the NCI-H1975 EGFR L858R / T790M / C797S cell subcutaneous xenograft tumor model (calculated based on tumor volume 35 days after administration). Group Tumor volume (m²) 1 TGI (%) 2 O value 3 O value 4 Blank control group 1615.42 ± 190.27 - - - ADC-13 (6 mg / kg) 31.02 ± 4.45 98.09 *** *** ADC-14 (6 mg / kg) 490.04 ± 67.43 68.37 ** - 1. Tumor volume is expressed as mean ± standard error; 2. Tumor growth inhibition is calculated by TGI (TGI (%) = [1 - (T35 / T0) / (V35 / V0)]). <100) reflects; 3. 0 value calculated based on tumor volume represents P<0.05, ** represents pv0.01, *** represents pvQ.001, ns represents no significance)ο Tumor volume comparison between each experimental group and the blank control group. 4. p value calculated based on tumor volume (* represents pv0.05, ** represents pv0.01, *** represents pvQJ)01, ns represents no significance). Tumor volume comparison between the bispecific antibody ADC and the control ADC experimental groups in this embodiment. The experimental results are shown in Figure 18 and Table 31. In the non-small cell lung cancer tumor model resistant to the third-generation TKI osimertinib, all experimental groups showed significant inhibition of tumor growth compared with the blank control group; at the same dosage, the antibody conjugate of this invention had better tumor inhibition than the control ADC, and the mice in each administration group tolerated it well with no significant decrease in body weight. Sequence SEQ ID NO: Name Sequence 1Hl CDR 1 TYGMH 2 H1CDR 2 VIWDDGSYKYYGDSVKG 3 Hl CDR 3 DGITMVRGVMKDYFDY 4 L1CDR1 RASQDISSALV 5 L1CDR2 DASSLES 6 L1CDR3 QQFNSYPLT 7 H2CDR 1 SAYYWN 69 WO 2025 / 016453 PCT / CN2024 / 106435 8 H2CDR 2 YISYDGRNNXNPSLKN, X is Y or F 9 H2CDR 3 DGDYDYFDY 10 L2CDR1 RASQDISNYLN 11 L2CDR2 YTSILHS 12 L2CDR3 QQGDTLPPT 13 H1FR1 QVQLVESGGGVVQPGRSLRLSCAASGFTFS 14 H1FR2 WVRQAPGKGLEWVA 15 H1FR3 RFTISRDNSKNTLYLQMNSLRAEDTAVYYCAR 16 H1FR4 WGQGTLVTVSS 17 L1FR1 AIQLTQSPSSLSASVGDRVTITC 18 L1FR2 / L2FR2 WYQQKPGKAPKLLIY 19 L1FR3 GVPSRFSGSESGTDFTLTISSLQPEDFATYYC 20 L1FR4 FGGGTKVEIK 21 H2FR1 QVQLQESGPGLVKPSETLSLTCTVSGYSIT 22 H2FR2 WIRQPFGKGLEWMG 23 H2FR3 RVTISRDTSKNQFSLKLSSVTAADTAVYYCAR 24 H2FR4 WGQGTTVTVSS 25 L2FR1 DIQMTQSPSSLSASVGDRVTITC 26 L2FR3 GVPSRFSGSGSGTDYTFTISSLQPEDIATYFC 27 L2FR4 FGGGTKLEIK 28 VH1 QVQLVESGGGVVQPGRSLRLSCAASGFTFSTYGMHWVRQAPGKGLEWVAVI WDDGSYKYYGDSVKGRFT1SRDNSKNTLYLQMNSLRAEDTAVYYCARDG1T MVRGVMKDYFDYWGQGTLVTVSS 29 VL1 AIQLTQSPSSLSASVGDRVTITCRASQDISSALVWYQQKPGKAPKLLIYDASSLESGVPSRFSGSESGTDFTLT1SSLQPEDFATYYCQQFNSYPLTFGGGTKVE1K 30 VH2 QVQLQESGPGLVKPSETLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLSSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSS 31 VL2 DIQMTQSPSSLSASVGDRVTITCRASQDISNYLNWYQQKPGKAPKLLIYYTSIL HSGVPSRFSGSGSGTDYTFTISSLQPEDIATYFCQQGDTLPPTFGGGTKLEIK 32 CLI RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNS QESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRG EC 33 CL2 SSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVH TFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSC 34 C1H1 ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGTQTY1CNVNHKPSNTKVDKKVEPKSC 35 C2H1 ASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNS QESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRG EC 36 Fcl / Fc2 SVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQ PREPQVYTLPPSRDELTKNQVSLTCLVKGFYPSD1AVEWESNGQPENNYKTTPP VLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 37 Heavy chain HlQVQLVESGGGVVQPGRSLRLSCAASGFTFSTYGMHWVRQAPGKGLEWVAVI WDDGSYKYYGDSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARDGIT MVRGVMKDYFDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLV KDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYIC NVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLM1 SRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVS VLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDE LTKNQVSLWCLVKGFYPSD1AVEWESNGQPENNYKTTPPVLDSDGSFFLYSKL TVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 70 WO 2025 / 016453 PCT / CN2024 / 106435 38 Light chain Ll AIQLTQSPSSLSASVGDRVTITCRASQDISSALVWYQQKPGKAPKLLIYDASSL ESGVPSRFSGSESGTDFTLTISSLQPEDFATYYCQQFNSYPLTFGGGTKVEIKRT VAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQES VTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC 39 Heavy chain H2 QVQLQESGPGLVKPSETLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLSSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQ GLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCWVDVSHEDPEVK FNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVS NKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLSCAVKGFYPSDIA VEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKSRWQQGNVFSCSVMHE ALHNHYTQKSLSLSPGK 40 Light chain L2 DIQMTQSPSSLSASVGDRVTITCRASQDISNYLNWYQQKPGKAPKLLIYYTSIL HSGVPSRFSGSGSGTDYTFTISSLQPEDIATYFCQQGDTLPPTFGGGTKLEIKSS ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGTQTYICWNHKPSNTKVDKKVEPKSC 41 Heavy chain Hl QVQLVESGGGVVQPGRSLRLSCAASGFTFSTYGMHWVRQAPGKGLEWVAVI WDDGSYKYYGDSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARDGIT MVRGVMKDYFDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLV KDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYIC NVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLM1 SRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVS VLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPCRD ELTKNQVSLWCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSK LTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 42 Heavy chain H2 QVQLQESGPGLVKPSETLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYISYDGRNNFNPSLKNRVTISRDTSKNQFSLKLSSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQ GLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVT CVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVCTLPPSRDELTKNQ VSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKS RWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 43 Heavy chain Hl QVQLVESGGGVVQPGRSLRLSCAASGFTFSTYGMHWVRQAPGKGLEWVAVI WDDGSYKYYGDSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARDGIT MVRGVMKDYFDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLV KDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYIC NVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMI SRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVS VLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDE LTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLT VDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 44 Heavy chain H2 QVQLQESGPGLVKPSETLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLSSVTAADTAVYYCARDGDYDYFDYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQ GLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVT CVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLWCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKS RWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 45 Heavy chain H1 QVQLVESGGGVVQPGRSLRLSCAASGFTFSTYGMHWVRQAPGKGLEWVAVI WDDGSYKYYGDSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARDGIT MVRGVMKDYFDYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLV 71 WO 2025 / 016453 PCT / CN2024 / 106435 KDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYIC NVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMI SRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVS VLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVCTLPPSRDE LTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLT VDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 46 Heavy chain H2 QVQLQESGPGLVKPSETLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLSSVTAADTAVYYCARDGDYDYFDYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQ GLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLM1SRTPEVT CVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPCRDELTKNQ VSLWCLVKGFYPSD1AVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKS RWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 47 Heavy chain Hl QVQLVESGGGVVQPGRSLRLSCAASGFTFSTYGMHWVRQAPGKGLEWVAVI WDDGSYKYYGDSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARDGIT MVRGVMKDYFDYWGQGTLVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLL NNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEK HKVYACEVTHQGLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKP KDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNS TYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYT LPPSRDELTKNQVSLWCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGS FFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 48 Light chain LI AIQLTQSPSSLSASVGDRVTITCRASQDISSALVWYQQKPGKAPKLLIYDASSL ESGVPSRFSGSESGTDFTLTISSLQPEDFATYYCQQFNSYPLTFGGGTKVEIKSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSC 49 Heavy chain H2 QVQLQESGPGLVKPSETLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLSSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLM1SRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLSC AVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKSRWQQ GNVFSCSVMHEALHNHYTQKSLSLSPGK 50 Light chain L2 DIQMTQSPSSLSASVGDRVTITCRASQDISNYLNWYQQKPGKAPKLLIYYTSIL HSGVPSRFSGSGSGTDYTFT1SSLQPED1ATYFCQQGDTLPPTFGGGTKLE1KRT VAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQES VTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC 51 Heavy chain Hl QVQLVESGGGVVQPGRSLRLSCAASGFTFSTYGMHWVRQAPGKGLEWVAVI WDDGSYKYYGDSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARDGIT MVRGVMKDYFDYWGQGTLVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEK HKVYACEVTHQGLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKP KDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNS TYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAP1EKT1SKAKGQPREPQVYT LPPCRDELTKNQVSLWCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGS FFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 52 Heavy chain H2 QVQLQESGPGLVKPSETLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLSSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVCTLPPSRDELTKNQVSLSC 72 WO 2025 / 016453 PCT / CN2024 / 106435 AVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKSRWQQ GNVFSCSVMHEALHNHYTQKSLSLSPGK 53 Heavy chain Hl QVQLVESGGGVVQPGRSLRLSCAASGFTFSTYGMHWVRQAPGKGLEWVAVI WDDGSYKYYGDSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARDGIT MVRGVMKDYFDYWGQGTLVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEK HKVYACEVTHQGLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKP KDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNS TYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYT LPPSRDELTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGS FFLVSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 54 Heavy chain H2 QVQLQESGPGLVKPSETLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLSSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLWC LVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSPGK 55 Heavy chain Hl QVQLVESGGGVVQPGRSLRLSCAASGFTFSTYGMHWVRQAPGKGLEWVAVI WDDGSYKYYGDSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARDGIT MVRGVMKDYFDYWGQGTLVTVSSASVAAPSVF1FPPSDEQLKSGTASVVCLL NNFYPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKP KDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNS TYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVCT LPPSRDELTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGS FFLVSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 56 Heavy chain H2 QVQLQESGPGLVKPSETLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLSSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAP1EKT1SKAKGQPREPQVYTLPPCRDELTKNQVSLWC LVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSPGK 57 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQ GLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALPAP1EKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKS RWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 58 Light chain L2 DIQMTQSPDSLSASLGDRVTITCRASQDISNYLNWYQQKPGKAPKLLIYYTSIL HSGVPSRFSGSGSGTDYTFTISSLQPEDIATYFCQQGDTLPPTFGGGTKLEIKSS ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKKVEPKSC 59 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQ GLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVT CVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH 73 WO 2025 / 016453 PCT / CN2024 / 106435 QDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVCTLPPSRDELTKNQ VSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKS RWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 60 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYISYDGRNNFNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQ GLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVT CVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLWCLVKGFYPSD1AVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKS RWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 61 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQ GLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLM1SRTPEVT CVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPCRDELTKNQ VSLWCLVKGFYPSD1AVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKS RWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 62 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYFDYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLSC AVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKSRWQQ GNVFSCSVMHEALHNHYTQKSLSLSPGK 63 Light chain L2 DIQMTQSPDSLSASLGDRVTITCRASQDISNYLNWYQQKPGKAPKLLIYYTSIL HSGVPSRFSGSGSGTDYTFTISSLQPEDIATYFCQQGDTLPPTFGGGTKLEIKRT VAAPSVF1FPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQES VTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC 64 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLM1SRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVCTLPPSRDELTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKSRWQQ GNVFSCSVMHEALHNHYTQKSLSLSPGK 65 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVT1SRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLM1SRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLWC LVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSPGK 66 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVV 74 WO 2025 / 016453 PCT / CN2024 / 106435 DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPCRDELTKNQVSLWCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSPGK 67 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNYNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQ GLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVT CVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALPAP1EKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKS RWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 68 Light chain L2 DIQMTQEPSSLSASVGDRVTITCRASQDISNYLNWYQQKPGKAPKLLIYYTSIL HSGVPSRFSGSGSGTDYTFTISSLQPEDIATYFCQQGDTLPPTFGGGTKLEIKSS ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGTQTY1CNVNHKPSNTKVDKKVEPKSC 69 Heavy chain HZ QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNYNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVT CVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVCTLPPSRDELTKNQ VSLSCAVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKS RWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 70 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNYNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQ GLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVT CVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALPAP1EKTISKAKGQPREPQVYTLPPSRDELTKNQ VSLWCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKS RWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 71 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNYNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQ WKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQ GLSSPVTKSFNRGECDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLH QDWLNGKEYKCKVSNKALPAP1EKTISKAKGQPREPQVYTLPPCRDELTKNQ VSLWCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKS RWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 72 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNYNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLSC AVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKSRWQQ GNVFSCSVMHEALHNHYTQKSLSLSPGK 73 Light chain L2 DIQMTQEPSSLSASVGDRVTITCRASQDISNYLNWYQQKPGKAPKLLIYYTSIL HSGVPSRFSGSGSGTDYTFTISSLQPEDIATYFCQQGDTLPPTFGGGTKLEIKRT VAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQES VTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC 75 WO 2025 / 016453 PCT / CN2024 / 106435 74 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYISYDGRNNYNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVCTLPPSRDELTKNQVSLSC AVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLVSKLTVDKSRWQQ GNVFSCSVMHEALHNHYTQKSLSLSPGK 75 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNYNPSLKNRVT1SRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLM1SRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPSRDELTKNQVSLWC LVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSPGK 76 Heavy chain H2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNYNPSLKNRVT1SRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYFDYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSSLGTQTYICNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAPIEKTISKAKGQPREPQVYTLPPCRDELTKNQVSLWC LVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSPGK 77 H2CDR 2 YISYDGRNNYNPSLKN 78 H2CDR 2 YISYDGRNNFNPSLKN 79 VH2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNFNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSS 80 VH2 QVQLQESGPGLVKPSDTLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS YDGRNNYNPSLKNRVTISRDTSKNQFSLKLDSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSS 81 VL2 DIQMTQSPDSLSASLGDRVTITCRASQDISNYLNWYQQKPGKAPKLLIYYTSIL HSGVPSRFSGSGSGTDYTFTISSLQPEDIATYFCQQGDTLPPTFGGGTKLEIK 82 VL2 DIQMTQEPSSLSASVGDRVTITCRASQDISNYLNWYQQKPGKAPKLLIYYTSIL HSGVPSRFSGSGSGTDYTFTISSLQPEDIATYFCQQGDTLPPTFGGGTKLEIK 83 anti-EGFR Heavy Chain QVQLVESGGGVVQPGRSLRLSCAASGFTFSTYGMHWVRQAPGKGLEWVAVIWDDGSYKYYGDSVKGRFTISRDNSKNTLYLQMNSLRAEDTAVYYCARDGIT MVRGVMKDYFDYWGQGTLVTVSS ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTF PAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKRVEPKSCDKT HTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFN WYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNK ALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVE WESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEAL HNHYTQKSLSLSPGK 84 anti-EGFR L chain AIQLTQSPSSLSASVGDRVTITCRASQDISSALVWYQQKPGKAPKLLIYDASSL ESGVPSRFSGSESGTDFTLTISSLQPEDFATYYCQQFNSYPLTFGGGTKVEIK RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNS QESVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRG EC 85 anti-QVQLQESGPGLVKPSETLSLTCTVSGYSITSAYYWNWIRQPFGKGLEWMGYIS 76 WO 2025 / 016453 PCT / CN2024 / 106435 HER3 H chain YDGRNNFNPSLKNRVTISRDTSKNQFSLKLSSVTAADTAVYYCARDGDYDYF DYWGQGTTVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVS WNSGALTSGVHTFPAVLQSS—GLYSLSSVVTVPSSS- LGTQTYICNVNHKPSNTKVDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQY NSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQPREPQV YTLPPSRDELTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSD GSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 86 anti-HER3 L chain DIQMTQSPSSLSASVGDRVTITCRASQDISNYLNWYQQKPGKAPKLLIYYTSIL HSGVPSRFSGSGSGTDYTFTISSLQPEDIAT— YFCQQGDTLPPTFGGGTKLE1KRTVAAPSVF1FPPSDEQLKSGTASVVCLLNNF YPREAKVQWKVDNALQSGNSQESVTEQDSKDSTYSLSSTLTLSKADYEKHK VYACEVTHQGLSSPVTKSFNRGEC 87 Cetuximab heavy chain QVQLKQSGPGLVQPSQSLSITCTVSGFSLTNYGVHWVRQSPGKGLEWLGVIW SGGNTDYNTPFTSRLSINKDNSKSQVFFKMNSLQSNDTAIYYCARALTYYDYE FAYWGQGTLVTVSAASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTV SWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTY1CNVNHKPSNTK VDKKVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVVV DVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAP1EKT1SKAKGQPREPQVYTLPPSRDELTKNQVSLTC LVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSPGK 88 Cetuximab light chain DILLTQSPVILSVSPGERVSFSCRASQSIGTNIHWYQQRTNGSPRLLIKYASESISGIPSRFSGSGSGTDFTLSINSVESEDIADYYCQQNNNWPTTFGAGTKLELKRTV AAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQES VTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC 89 hinge region DKTHTCPPCPAPELLGGP 90 heavy chain H2 DIQMTQSPSSLSASVGDRVTITCRASQDISNYLNWYQQKPGKAPKLLIYYTSIL HSGVPSRFSGSGSGTDYTFTISSLQPEDIATYFCQQGDTLPPTFGGGTKLEIKGG GGSGGGGSGGGGSGGGGSQVQLQESGPGLVKPSETLSLTCTVSGYSITSAYY WNWIRQPFGKGLEWMGYISYDGRNNFNPSLKNRVTISRDTSKNQFSLKLSSV TAADTAVYYCARDGDYDYFDYWGQGTTVTVSSEPKSSDKTHTCPPCPAPELL GGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNA KTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKT1SKA KGQPREPQVYTLPPSRDELTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYK TTPPVLDSDGSFFLVSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLS PGK 91 SI-1X6.4 heavy chain QVQLKQSGPGLVQPSQSLSITCTVSGFSLTNYGVHWVRQSPGKGLEWLGVIW SGGNTDYNTPFTSRLSINKDNSKSQVFFKMNSLQSNDTAIYYCARALTYYDYE FAYWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTV SWNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSSLGTQTYICNWHKPSNTK VDKRVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVWDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWL NGKEYKCKVSNKALPAP1EKT1SKAKGQPREPQVYTLPPSRDELTKNQVSLTC LVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSKLTVDKSRWQQG NVFSCSVMHEALHNHYTQKSLSLSPGGGGGSGGGGSQVQLQESGGGLVKPG GSLRLSCAASGFTFSSYWMSWVRQAPGKGLEWVANINRDGSASYYVDSVKG RFTISRDDAKNSLYLQMNSLRAEDTAVYYCARDRGVGYFDLWGRGTLVTVSS GGGGSGGGGSGGGGSQSALTQPASVSGSPGQSITISCTGTSSDVGGYNFVSWY QQHPGKAPKLM1YDVSDRPSGVSDRFSGSKSGNTASL11SGLQADDEADYYCS SYGSSSTHVIFGGGTKVTVL 92 SI- 1X6.4 light chain DILLTQSPVILSVSPGERVSFSCRASQSIGTNIHWYQQRTNGSPRLLIKYASESIS G1PSRFSGSGSGTDFTLS1NSVESEDIADYYCQQNNNWPTTFGAGTKLELKRTV AAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQES VTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGEC 93 Fcl SVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTK PREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQ 77 WO 2025 / 016453 PCT / CN2024 / 106435 PREPQVYTLPPSRDELTKNQVSLWCLVKGFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 94 Fc2 SVFLFPPKPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKALPAPIEKTISKAKGQ PREPQVYTLPPSRDELTKNQVSLSCAVKGFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLVSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK 95 Chain Area GGGGSGGGGSGGGGSGGGGS 96 Chain Area EPKSSDKTHTCPPCPAPELLGGP While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. Therefore, the scope of protection of the present invention is defined by the appended claims. 78 WO 2025 / 016453 PCT / CN2024 / 106435 Claim 1. A bispecific antibody comprising an EGFR-binding domain and a HER3-binding domain, characterized in that the EGFR-binding domain comprises a heavy chain variable region VH1 and a light chain variable region VL1, and the HER3-binding domain comprises a heavy chain variable region VH2 and a light chain variable region VL2; wherein the amino acid sequences of H1CDR1, H1CDR2, and H1CDR3 contained in VH1 are as shown in SEQ ID NO:1, SEQ ID NO:2, and SEQ ID NO:3, respectively; the amino acid sequences of L1CDR1, L1CDR2, and L1CDR3 contained in VL1 are as shown in SEQ ID NO:4, SEQ ID NO:5, and SEQ ID NO:6, respectively; and the amino acid sequences of H2CDR1, H2CDR2, and H2CDR3 contained in VH2 are as shown in SEQ ID NO:4, SEQ ID NO:5, and SEQ ID NO:6, respectively. The amino acid sequences of L2CDR1, L2CDR2, and L2CDR3 contained in the VL2 are shown in SEQ ID NO: 10, SEQ ID NO: 11, and SEQ ID NO: 12, respectively. 2. The bispecific antibody according to claim 1, characterized in that the amino acid sequence of the H2CDR2 is shown in SEQ ID NO: 77 or 78; preferably, the amino acid sequences of the frame regions H1FRL, H1FR2, H1FR3, and H1FR4 contained in the VH1 are shown in SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, and SEQ ID NO: 16, respectively, or have a concentration of at least 90%, 91%, and 92% thereof.93%, 94%, 95%, 96%, 97%, 98%, or 99% identity; the amino acid sequences of the frame regions L1FR1, L1FR2, L1FR3, and H1FR4 contained in the VL1 are as shown in SEQ ID NO:17, SEQ ID NO:18, SEQ ID NO:20, or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with them; the amino acid sequence of the frame region H2FR1 contained in the VH2 is as shown in SEQ ID NO:21, or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it, for example, having an E16D mutation in SEQ ID NO:21; the amino acid sequences of the frame regions H2FR2 and H2FR4 are as shown in SEQ ID NO:22 and SEQ ID NO:20, respectively. The amino acid sequence of frame region H2FR3 is as shown in SEQ ID NO:23 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it, for example, having the S18D mutation in SEQ ID NO:23; the amino acid sequence of frame region L2FR1 included in VL2 is as shown in SEQ ID NO:25 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it, for example, having the S9D and V15L mutations, or the S7E mutation in SEQ ID NO:25; the amino acid sequences of frame regions L2FR2, L2FR3, and L2FR4 are as shown in SEQ ID NO:18, SEQ ID NO:26, and SEQ ID NO:26, respectively. The amino acid sequence of VH1 is as shown in SEQ ID NO:27 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it. 3. The bispecific antibody according to claim 1 or 2, characterized in that the amino acid sequence of VH1 is as shown in SEQ ID NO:28, the amino acid sequence of VL1 is as shown in SEQ ID NO:29, the amino acid sequence of VH2 is as shown in SEQ ID NO:30, SEQ ID NO:79, or SEQ ID NO:80, and the amino acid sequence of VL2 is as shown in SEQ ID NO:31, SEQ ID NO:81, or SEQ ID NO:82; preferably, the amino acid sequences of VH1, VL1, VH2, and VL2 of the bispecific antibody are respectively as shown in SEQ ID NO:28.ID NO:28, 79 WO 2025 / 016453 PCT / CN2024 / 106435 SEQ ID NO:29, SEQ ID NO:30 and SEQ ID NO:31; or, as shown in SEQ ID NO:28, SEQ ID NO:29 > 0B(52]^0:79 and 5F(321^0:81 respectively; or, as shown in SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:79 and SEQ ID NO:31 respectively; or, as shown in SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:80 and SEQ ID NO:82 respectively. The bispecific antibody according to any one of claims 1-3, characterized in that the EGFR-binding domain and the HER3-binding domain further comprise a light chain constant region and a heavy chain constant region, respectively; the EGFR-binding domain comprises a light chain constant region CL1 and a heavy chain constant region HC1; and the HER3-binding domain comprises a light chain constant region CL2 and a heavy chain constant region HC2; wherein the amino acid sequences of CL1 and CL2 are as shown in SEQ ID NO:32 or SEQ ID NO:33, or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with them, and the amino acid sequences of CL1 and CL2 are not the same sequence; and / or, HC1 comprises C1H1 and Fc1, and HC2 comprises C2H1 and Fc2; wherein the amino acid sequences of C1H1 and C2H1 are as shown in SEQ ID NO:34 or SEQ ID NO:35. The amino acid sequences of Fcl and Fc2 are variant sequences of the amino acid sequence shown in SEQ ID NO:36 or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it, and the amino acid sequences of C1H1 and C2H1 are not the same sequence; the amino acid sequences of Fcl and Fc2 are variant sequences of the amino acid sequence shown in SEQ ID NO:36 or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it, for example, having T146W, or SI34c and T146W, or T146S, LI48A and y187V, or y349C, T366S, L368A and y407V mutations in SEQ ID NO:36, and the amino acid sequences of Fcl and Fc2 are not the same sequence; Preferably, the amino acid sequences of CL1 and CL2 are as shown in SEQ ID NO:32 or SEQ ID NO:33, respectively; the amino acid sequences of C1H1 and C2H1 are as shown in SEQ ID NO:34 or SEQ ID NO:35, respectively; and the amino acid sequences of Fcl and Fc2 are as shown in SEQ ID NO:35.Variant sequences of the amino acid sequence shown in SEQ ID NO:36, for example, having T146W, or S134C and T146W, or T146S, L148A and Y187V, or Y349C, T366S, L368A and Y407V mutations on SEQ ID NO:36; More preferably, Fcl and Fc2 are connected by disulfide bonds and a Knob into Hole structure in the less chain region, wherein Fcl is knob-Fc and Fc2 is hole-Fc, or Fc2 is knob-Fc and Fcl is hole-Fc; Even more preferably, C1H1 and Fcl, C2H1 and Fc2 are connected by a less chain region, wherein the amino acid sequence of the less chain region is as shown in SEQ ID NO:89. 5. The bispecific antibody according to any one of claims 1-3, characterized in that the EGFR binding domain comprises a light chain constant region CL1 and a heavy chain constant region HC1, and the HER3 binding domain comprises a heavy chain constant region HC2; wherein the amino acid sequence of CL1 is as shown in SEQ ID NO:32 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity with it; and / or, HC1 comprises C1H1 and Fcl, and HC2 comprises Fc2; wherein the amino acid sequence of C1H1 is as shown in SEQ ID NO:34 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity with it; and the amino acid sequences of Fcl and Fc2 are variant sequences of the amino acid sequence shown in SEQ ID NO:36 or have at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identity with it. 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity; Preferably, the amino acid sequence of CL1 is as shown in SEQ ID NO:32, the amino acid sequence of C1H1 is as shown in SEQ ID NO:34, and the amino acid sequences of Fcl and Fc2 are as shown in SEQ ID NO:93 and 94, respectively; More preferably, Fcl and Fc2 are connected by disulfide bonds and a knob-into-hole structure in the chain region, wherein Fcl is a knob-Fc, and Fc2 is a hole-Fc, or Fc2 is a knob-Fc and Fcl is a hole-Fc; Even more preferably, C1H1 and Fcl are connected by a chain region with an amino acid sequence as shown in SEQ ID NO:89; VL2 and VH2 are connected by an amino acid sequence as shown in SEQ ID NO:80 WO 2025 / 016453 PCT / CN2024 / 106435 Fc, and Fc2 is a hole-Fc, or Fc2 is a knob-Fc and Fcl is a hole-Fc; Further preferably, C1H1 and Fcl are connected by a chain region with an amino acid sequence as shown in SEQ ID NO:89; VL2 and VH2 are connected by an amino acid sequence as shown in SEQ ID NO:80 WO 2025 / 016453 PCT / CN2024 / 106435 Fc, and Fc2 is a hole-Fc, or Fc2 is a knob-Fc and Fcl is a hole-Fc; NO:95 shows the linker region; VH2 and Fc2 are connected by an amino acid sequence as shown in SEQ ID.NO:96 shows the connection of the chain region. 6. The bispecific antibody according to any one of claims 1-3 or 5, characterized in that the bispecific antibody comprises a heavy chain H1, a light chain L1, and a heavy chain H2, wherein the amino acid sequence of H1 is as shown in SEQ ID NO:37 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it, and / or, the amino acid sequence of L1 is as shown in SEQ ID NO:38 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it, and / or, the amino acid sequence of H2 is as shown in SEQ ID NO:90 or has at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identity with it; preferably, the amino acid sequences of the heavy chain H1, light chain L1, and heavy chain H2 are as shown in SEQ ID NO:37, SEQ ID NO:38, and SEQ ID NO:39, respectively. NO:90 is shown. 7. The bispecific antibody according to any one of claims 1-4, characterized in that the amino acid sequences of the heavy chain H1, light chain L1, heavy chain H2, and light chain L2 of the bispecific antibody are as shown in SEQ ID NO:37, SEQ ID NO:38, SEQ ID NO:39, and SEQ ID NO:40, respectively; or, as shown in SEQ ID NO:41, SEQ ID NO:43, SEQ ID NO:45, SEQ ID NO:47, SEQ ID NO:51, SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:37, SEQ ID NO:41, SEQ ID NO:43, SEQ ID NO:45, SEQ ID NO:47, SEQ ID NO:51, SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:37, and SEQ ID NO:40, respectively. NO:4k are as shown in SEQ ID NO:43, SEQ ID NO:45, SEQ ID NO:38, SEQ ID NO:42 and SEQ ID NO:40 respectively; or, SEQ ID NO:38, SEQ ID NO:44 and SEQ ID NO:40 respectively; or, SEQ ID NO:38, SEQ ID NO:46 and SEQ ID NO:40 respectively; or,As shown in SEQ ID NO:48, SEQ ID NO:49 and SEQ ID NO:50; or, as shown in SEQ ID NO:48, SEQ ID NO:52 and SEQ ID NO:50; or, as shown in SEQ ID NO:48, SEQ ID NO:54 and SEQ ID NO:50; or, as shown in SEQ ID NO:48, SEQ ID NO:56 and SEQ ID NO:50; or, as shown in SEQ ID NO:38, SEQ ID NO:57 and SEQ ID NO:58; or, as shown in SEQ ID NO:38, SEQ ID NO:59 and SEQ ID NO:58; or, as shown in SEQ ID NO:38, SEQ ID NO:60 and SEQ ID NO:58; or, as shown in SEQ ID NO:38, SEQ ID NO:61 and SEQ ID NO:58; or, as shown in SEQ ID NO:48, SEQ ID NO:62 and SEQ ID NO:63; or, As shown in SEQ ID NO:48, SEQ ID NO:64 and SEQ ID NO:63; or, as shown in SEQ ID NO:48, SEQ ID NO:65 and SEQ ID NO:63; or, as shown in SEQ ID NO:48, SEQ ID NO:66 and SEQ ID NO:63; or, as shown in SEQ ID NO:38, SEQ ID NO:57 and SEQ ID NO:40; or, as shown in SEQ ID NO:38, SEQ ID NO:59 and SEQ ID NO:40; or, as shown in SEQ ID NO:38, SEQ ID NO:60 and SEQ ID NO:40; or, as shown in SEQ ID NO:38, SEQ ID NO:61 and SEQ ID NO:40; or, as shown in SEQ ID NO:47 and SEQ ID NO:5k respectively. For example, SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:37, SEQ ID NO:41, SEQ ID NO:43, SEQ ID NO:45, SEQ ID NO:47, SEQ ID NO:51, SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:48, SEQ ID NO:48.SEQ ID NO:48, SEQ ID NO:48, SEQ ID NO:38, SEQ ID NO:38, SEQ ID NO:38, SEQ ID NO:38, SEQ ID NO:48, SEQ ID NO:48, SEQ ID NO:48, SEQ ID NO:48, SEQ ID NO:62 and SEQ ID NO:50; or, SEQ ID NO:64 and SEQ ID NO:50; or, SEQ ID NO:65 and SEQ ID NO:50; or, SEQ ID NO:66 and SEQ ID NO:50; or, SEQ ID NO:67 and SEQ ID NO:68; or, SEQ ID NO:69 and SEQ ID NO:68; or, SEQ ID NO:70 and SEQ ID NO:68; or, SEQ ID NO:71 and SEQ ID NO:68 8. An isolated nucleic acid, characterized in that the nucleic acid encodes the bispecific antibody as described in any one of claims 1 to 7. 9. A recombinant expression vector, characterized in that the recombinant expression vector comprises the nucleic acid as described in claim 8. 10. A transformant, characterized in that the transformant contains the nucleic acid as described in claim 8 or the recombinant expression vector as described in claim 9 in a host cell; preferably, the host cell is a eukaryotic cell, preferably a mammalian cell, such as a CHO cell. 11. A method for preparing the bispecific antibody as described in any one of claims 1 to 7, the method comprising culturing the transformant as described in claim 10 to obtain the bispecific antibody. 12. A bispecific antibody-drug conjugate, its tautomers, enantiomers, diastereomers, or mixtures of isomers, or a pharmaceutically usable salt thereof, characterized in that the bispecific antibody-drug conjugate comprises: a bispecific antibody or its antigen-binding fragment as described in any one of claims 1 to 7, a linker unit L, and a cytotoxic drug. 13. The bispecific antibody-drug conjugate as described in claim 12, its tautomers, enantiomers, diastereomers, or mixtures of isomers, or a pharmaceutically usable salt thereof, characterized in that the cytotoxic drug is camptothecin and its derivatives; preferably, the cytotoxic drug has a structure as shown in formula (a1), its tautomers, enantiomers, or diastereomers,(A-1) 82 WO 2025 / 016453 PCT / CN2024 / 106435 Wherein, M is -IAlLC(O)-; I? is -NH-, O or S, preferably -O- or more preferably -O-, and I? is connected to the connector unit L; L' is -(C(Rja)(Rjb))m-CH2-, a C3-C6 saturated cycloalkylene group or a 3-6 saturated heterocyclic group, wherein the C3-C6 saturated cycloalkylene group and the 3-6 saturated heterocyclic group are each independently optionally substituted by one or more R2a; m is selected from 1, 2, 3 and 4; the heteroatoms in the 3-6 saturated heterocyclic group are each independently N, O and S, and the number of heteroatoms is 1, 2 or 3; each Ria and Rib is independently hydrogen, halogen, hydroxyl, amino or C1-C6 alkyl, wherein the C1-C6 alkyl group is optionally substituted by one or more halogens; R2a is selected from halogens, hydroxyl groups, amino groups, and CLC6 alkyl groups, wherein the CLC6 alkyl group is optionally substituted with one or more halogens. 14. The bispecific antibody-drug conjugate, its tautomers, enantiomers, diastereomers, or mixtures of isomers, or pharmaceutically usable salts thereof, as described in claim 13, characterized in that U is -(C(RS)(Rlb))»CH2-; each RS is selected from: hydrogen, halogens, and CLC6 alkyl groups; each R” is selected from: hydrogen, halogens, and CLC6 alkyl groups; or, U is -(C(Rla)(Rlb))m-CH2-; R3 is a CLC6 alkyl group, preferably an alkyl group; R1 is selected from: hydrogen and CLC6 alkyl groups, preferably selected from: hydrogen and CLC3 alkyl groups; or, U is -(C(Rla)(R"))m-CH2-; R is -CE; R” is selected from: hydrogen and -CH3; Alternatively, U is a C3-C6 saturated cyclohexane or a 3-6 membered saturated heterocyclic group, preferably a C3-C6 saturated cyclohexane, wherein the C3-C6 saturated cyclohexane and the 3-6 membered saturated heterocyclic group are each independently and optionally substituted by one or more R2a, each R2a being independently a halogen or a C1-C6 alkyl group; or, U is optionally substituted by one or more R2a: cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl; each R2a is independently selected from: halogen and C1-C6 alkyl; or, U is 3α, β, or 3α; [The remaining text appears to be a series of characters and symbols, possibly a corrupted or incomplete translation. A more accurate translation would require the original, coherent text.] The bispecific antibody-drug conjugate, its tautomers, enantiomers, diastereomers, or mixtures of isomers, or pharmaceutically usable salts thereof, as described in claim 14, is characterized in that, in the structure shown in formula (a-1), M is -1ALy; I is 0;L1 is -(C(Rla)(Rlb))m-CH2- or a C3-C6 saturated cycloalkylene group, and the C3-C6 saturated cycloalkylene group is optionally substituted by one or more R2a; m is selected from 1 or 2; Ria and Rib are each independently selected from hydrogen, halogen, and C1-C6 alkyl, and the C1-C6 alkyl is optionally substituted by one or more halogens; R2a is selected from halogen and C1-C6 alkyl, and the C1-C6 alkyl is optionally substituted by one or more halogens. 16. The bispecific antibody-drug conjugate, its tautomer, enantiomer, diastereomer, or mixture of isomers, or its pharmaceutically acceptable salt according to any one of claims 13-15, wherein m is: 83 WO 2025 / 016453 PCT / CN2024 / 106435 17. The bispecific antibody-drug conjugate, its tautomer, enantiomer, diastereomer, or mixture of isomers, or its pharmaceutically acceptable salt according to any one of claims 12-16, wherein the cytotoxic drug is selected from any one of the following structures: 18. The bispecific antibody-drug conjugate, its tautomer, enantiomer, diastereomer, or mixture of isomers, or its pharmaceutically acceptable salt according to any one of claims 12-17, wherein the linker unit L is -La-Lb-Lc-; wherein La is connected to the cytotoxic drug; ο ο 5-8 alkylene -C(O)- C1-6 alkylene -C(O)- ■La is O or -C1-8 alkylene -C(O)-, preferably O or -C1-6 84 WO 2025 / 016453 PCT / CN2024 / 106435 ο alkylene -C(O)-, more preferably Further preferably a ob, where the a end is connected to Ab and the b end is connected to Lb; ·U- is a polypeptide of 2 to 6 natural amino acids -NH-, preferably a polypeptide of 2 to 4 natural amino acids -NH-, more preferably selected from any one of the following structures: or further preferably where the C end is connected to La and the d end is connected to Lb; is C1-6 alkylene, preferably C1-3 alkylene, more preferably g1 19. The bispecific antibody-drug conjugate, its tautomer, enantiomer, diastereomer, or mixture of isomers, or its pharmaceutically acceptable salt according to claim 18, wherein the linker unit L is 85 WO 2025 / 016453 PCT / CN2024 / 106435 ο θ' ΌΗ; preferablyWherein, P represents the average number of connections, and p is any integer or decimal from 1 to 10; preferably any integer or decimal from 3 to 9; for example, 4, 4.06, 4.10, 6, 6.1L, 6.05, 7.99, 7.98 or 8; Ab is the bispecific antibody or its antigen-binding fragment as described in any one of claims 1-7; m is defined as the antibody-drug conjugate as described in any one of claims 13-17; L is the linker unit L as described in claim 18 or 19. 21. The bispecific antibody-drug conjugate, its tautomers, enantiomers, diastereomers, or mixtures of isomers, or pharmaceutically usable salts thereof, as described in any one of claims 12-20, characterized in that the structure of the bispecific antibody-drug conjugate is as shown in formula (A-2a) or (A-2b): (A-2a) 86 WO 2025 / 016453 PCT / CN2024 / 106435 (A-2b), wherein p represents the average number of links, and p is selected from any integer or decimal from 1 to 10, preferably any integer or decimal from 3 to 9; for example, 4, 4.06, 4.10, 6, 6.1L, 6.05, 7.99, 7.98, or 8; Ab is the bispecific antibody or its antigen-binding fragment as described in any one of claims 1-7; L2 is -NH-, O, or S, preferably -O- or -S-; more preferably -O-; Xi is selected from C3-C6 cycloalkyl groups optionally substituted with 1, 2, or 3 R2a; X2 is selected from -(C(Rla)Rb))⁻CH2-; m is selected from 1 or 2; Ria and Rib are each independently hydrogen, halogen, or C1-C6 alkyl groups optionally substituted with 1, 2, or 3 halogens; R2a is selected from halogens, hydroxyl groups, amino groups, and C1-C6 alkyl groups, wherein the C1-C6 alkyl groups are optionally substituted with one or more halogens; preferably, the structure of the bispecific antibody-drug conjugate is selected from the following: P, 87 WO 2025 / 016453 PCT / CN2024 / 106435 ο N H p, ο H N NH ο ο p, 88 WO 2025 / 016453 PCT / CN2024 / 106435 P, 89 WO 2025 / 016453 PCT / CN2024 / 106435 p, p, and p, wherein p represents the average number of links, and p is any integer or decimal from 1 to 10, preferably any integer or decimal from 3 to 9; for example, 4, 4.06, 4.10, 6, 6.11, 6.05, 7.99, 7.98, or 8; Ab is a bispecific antibody or its antigen-binding fragment as described in any one of claims 1-7; preferably, Ab is selected from the bispecific antibody line DBXT001, DBXT002, DBXT003, and DBXT004; preferably...The antibody is selected from the bispecific antibody DBXT001 series, DBXT002 series and DBXT005-01; more preferably selected from the bispecific antibody DBXT001 series and DBXT005-01; and even more preferably selected from the bispecific antibody DBXT001-01 and DBXT005-01. 90 WO 2025 / 016453 PCT / CN2024 / 106435 22. The bispecific antibody-drug conjugate, its tautomers, enantiomers, diastereomers, or mixtures of isomers, or pharmaceutically usable salts thereof, as described in claim 21, characterized in that the bispecific antibody-drug conjugate is selected from the following, wherein P represents the average number of links, and p is any integer or decimal from 1 to 10, preferably any integer or decimal from 3 to 9; for example, 4, 4.06, 4.10, 6, 6.11, 6.05, 7.99, 7.98, or 8; preferably, the bispecific antibody-drug conjugate is selected from any of the following: 4 91 WO 2025 / 016453 PCT / CN2024 / 106435 4.06 6 92 WO 2025 / 016453 PCT / CN2024 / 106435 7.99 8 4 93 WO 2025 / 016453 PCT / CN2024 / 106435 94 WO 2025 / 016453 PCT / CN2024 / 106435 Among them, DBXTOOl-Ol is a bispecific antibody against EGFR and HER3, and the amino acid sequences of its heavy chain H1, light chain L1, heavy chain H2 and light chain L2 are shown in SEQ ID NO:37, SEQ ID NO:38, SEQ ID NO:39 and SEQ ID NO:40, respectively. 23. The bispecific antibody-drug conjugate, its tautomers, enantiomers, diastereomers, or mixtures of isomers, or pharmaceutically usable salts thereof, as described in any one of claims 12-21, characterized in that the bispecific antibody-drug conjugate P 95 WO 2025 / 016453 PCT / CN2024 / 106435 wherein p represents the average number of links, and p is any integer or decimal from 1 to 10, preferably any integer or decimal from 3 to 9, more preferably any integer or decimal from 4 to 6; for example, 5.99: DBXT005-01 is a bispecific antibody against EGFR and HER3, the amino acid sequence of its heavy chain H1 is as shown in SEQ ID NO: 37, the amino acid sequence of its light chain L1 is as shown in SEQ ID NO: 38, and the amino acid sequence of its heavy chain H2 is as shown in SEQ ID NO: 90. 24. The bispecific antibody-drug conjugate, its tautomer, enantiomer, or any of the claims 12-19The bispecific antibody-drug conjugate is characterized by: -pl, where p1 represents the number of links, and p1 is any integer from 1 to 10, preferably any integer from 3 to 9, more preferably any integer from 4 to 6; for example, 4, 5 or 6; DBXT005-01 is a bispecific antibody against EGFR and HER3, the amino acid sequence of its heavy chain H1 is shown in SEQ ID NO: 37, the amino acid sequence of its light chain L1 is shown in SEQ ID NO: 38, and the amino acid sequence of its heavy chain H2 is shown in SEQ ID NO: 90. 25. A method for preparing a bispecific antibody-drug conjugate, tautomer, enantiomer, diastereomer, or mixture of isomers, or a pharmaceutically usable salt thereof, as described in any one of claims 12-24, comprising the steps of: mixing the bispecific antibody dissolved in a buffer solution with an L-cytotoxic drug linker unit dissolved in a solvent under the action of a reducing agent to obtain the bispecific antibody-drug conjugate; wherein the reducing agent is preferably tris(2-caloethyl)phosphohydrochloride, the buffer solution is preferably ethylenediaminetetraacetic acid, and the solvent is preferably dimethylacetamide. 26. The method of claim 25, further comprising reacting an anti-EGFR and HER3 bispecific antibody with a compound of formula X2, for example, reacting DBXT005-01 with a compound of formula X2. 27. A pharmaceutical composition comprising a bispecific antibody as described in any one of claims 1 to 7, an isolated nucleic acid as described in claim 8, a recombinant expression vector as described in claim 9, a transformant as described in claim 10, and / or a bispecific antibody-drug conjugate as described in any one of claims 12 to 22, and a pharmaceutically acceptable carrier or excipient. 28. Use of the bispecific antibody as described in any one of claims 1-7, the isolated nucleic acid as described in claim 8, the recombinant expression vector as described in claim 9, the transformant as described in claim 10, the bispecific antibody-drug conjugate as described in any one of claims 12-24, and / or the pharmaceutical composition as described in claim 27 in the preparation of a medicament for treating and / or preventing cancer, preferably, wherein the cancer is an EGFR- and / or Her3-positive cancer, for example, the cancer is selected from breast cancer, skin cancer, gastric cancer, colorectal cancer, lung cancer, esophageal cancer, biliary tract cancer, head and neck cancer, thyroid cancer, ovarian cancer, endometrial cancer, pancreatic cancer, prostate cancer, bladder cancer, gastrointestinal cancer, digestive tract cancer, cervical cancer, squamous cell carcinoma, peritoneal cancer, liver cancer, kidney cancer, thyroid cancer, leukemia, etc.Malignant lymphoma, plasmama, myeloma, glioma, osteosarcoma, sarcoma, cavitary squamous cell carcinoma, and melanoma; preferably selected from breast cancer, colorectal cancer, skin cancer, lung cancer, esophageal cancer, and oral squamous cell carcinoma; the lung cancer is preferably non-small cell lung cancer, the skin cancer is preferably squamous cell carcinoma, and the colorectal cancer is preferably rectal cancer. 29. A method for treating and / or preventing cancer, comprising administering to a subject in need a bispecific antibody as described in any one of claims 1-7, a bispecific antibody-drug conjugate as described in any one of claims 12-24, and / or a pharmaceutical composition as described in claim 27; preferably, the cancer is an EGFR and / or Her3 positive cancer, for example, the cancer is selected from breast cancer, skin cancer, gastric cancer, colorectal cancer, lung cancer, esophageal cancer, biliary tract cancer, head and neck cancer, thyroid cancer, ovarian cancer, endometrial cancer, pancreatic cancer, prostate cancer, bladder cancer, gastrointestinal cancer, digestive tract cancer, cervical cancer, squamous cell carcinoma, peritoneal cancer, liver cancer, kidney cancer, thyroid cancer, leukemia, malignant lymphoma, plasmama, myeloma, glioma, osteosarcoma, sarcoma, cavitary squamous cell carcinoma, and melanoma; preferably selected from breast cancer, colorectal cancer, skin cancer, lung cancer, esophageal cancer, and oral squamous cell carcinoma; the lung cancer is preferably non-small cell lung cancer, the skin cancer is preferably squamous cell carcinoma, and the colorectal cancer is preferably rectal cancer. 30. A bispecific antibody as described in any one of claims 1 to 7, a bispecific antibody-drug conjugate as described in any one of claims 12 to 24, and / or a pharmaceutical composition as described in claim 27 for the prevention and / or treatment of cancer; preferably, the cancer is an EGFR and / or Her3 positive cancer, for example, the cancer is selected from breast cancer, skin cancer, gastric cancer, colorectal cancer, lung cancer, esophageal cancer, biliary tract cancer, head and neck cancer, thyroid cancer, ovarian cancer, endometrial cancer, pancreatic cancer, prostate cancer, bladder cancer, gastrointestinal cancer, digestive tract cancer, cervical cancer, squamous cell carcinoma, peritoneal cancer, liver cancer, kidney cancer, thyroid cancer, leukemia, malignant lymphoma, plasmacytoma, myeloma, glioma, osteosarcoma, sarcoma, cavitary squamous cell carcinoma, and melanoma; preferably selected from breast cancer, colorectal cancer, skin cancer, lung cancer, esophageal cancer, and oral squamous cell carcinoma; the lung cancer is preferably non-small cell lung cancer, the skin cancer is preferably squamous cell carcinoma, and the colorectal cancer is preferably rectal cancer. 31. A combination therapy, characterized in that it comprises administering, to a subject in need, a bispecific antibody as described in any one of claims 1-7, a bispecific antibody-drug conjugate as described in any one of claims 12-24, and / or a pharmaceutical composition as described in claim 27, respectively, and a second therapeutic agent; preferably, the cancer is an EGFR and / or Her3-positive cancer, for example, the cancer is selected from breast cancer, skin cancer, gastric cancer, colorectal cancer, lung cancer, esophageal cancer, biliary tract cancer, head and neck cancer, thyroid cancer, ovarian cancer, endometrial cancer, pancreatic cancer, prostate cancer, etc.WO 2025 / 016453 PCT / CN2024 / 106435 Cancer, bladder cancer, gastrointestinal cancer, digestive tract cancer, cervical cancer, squamous cell carcinoma, peritoneal cancer, liver cancer, kidney cancer, thyroid cancer, leukemia, malignant lymphoma, plasmacytoma, myeloma, glioma, osteosarcoma, sarcoma, oral squamous cell carcinoma and melanoma; preferably selected from breast cancer, colorectal cancer, skin cancer, lung cancer, esophageal cancer and oral squamous cell carcinoma; the lung cancer is preferably non-small cell lung cancer, the skin cancer is preferably cutaneous squamous cell carcinoma, and the colorectal cancer is preferably rectal cancer. 32. The use of the bispecific antibody according to any one of claims 1 to 7, the isolated nucleic acid according to claim 8, the recombinant expression vector according to claim 9, the transformant according to claim 10, the bispecific antibody-drug conjugate according to any one of claims 12 to 24 and / or the pharmaceutical composition according to claim 27 in the preparation of an EGFR and / or HER3 inhibitor. 98 WO 2025 / 016453 PCT / CN2024 / 106435 (IIu)s pl (Nu)5-g-0-· -■ LcolxgQ * - s + H ;5〕WV * iL(ru) Yunfan (IV!)-Jingku-(Nu)r ErjingW 5 s s: Zih3ή ·♦♦ 95 s Li -9-- -5 I1M H Beijing Er 5 - _3N 8 i - Changyi 5 • ii - 9-3-- Q Figure 1 / 11 WO 2025 / 016453 PCT / CN2024 / 106435 L ° -Gd-os- JiangLshan, JU 4 E.̂ OOHXmQ.̂̂ χτ-ω L9- ① dA°- Sashan Gonghuo uV -οώοοΗχωη- W 9 X _ S (W)z Songyun Zhucun z, 1 m (Hu)m Guanweiw ° Β Β ΗΨ 9 Ζ 1. L9- ω ^ ο ω - £ ShanH,_w< "Lshan 】u< LM OOlxm a Cun·9 X _ S (Hu)m Songw -w au.£ / 9 z l. 0< 2 Figure 2 / 11 WO 2025 / 016453 PCT / CN2024 / 106435 T47D (izl Alf San q a m San Yi Yun o p o 」H d) Antibody concentration (nM) Figure 3 A EG FR over &iiHER3i[ & i^CT26 (48 hours Il J) anti EGFR mAb anti IKiFR nv\bNCI-H1975 (48 hours) Figure 43 / 11 WO 2025 / 016453 PCT / CN2024 / 106435 •o o o o z..0000̂..0000̂ ■Ooi,.0000 (Mingcai 1 / % shandX noa) Discussion on black¥·piece ■0000« '00000̂ '0000̂ ^ (Iodine 1 shuchuanT x C33) looooob g u u / process ω work 8 4 / 11 WO 2025 / 016453 PCT / CN2024 / 106435 OE19 EGFR +, HEIR3 ++ 3000· · Blank control group ADC-1 (e E E) Need to control which -H-g 2000- 1000- 10 20 ADC-2 ADC-6 0+ 0 30 Days after administration (days) Figure 6 NCI-H441 EGFR ++, HER3 ++ (6 mina) Need to control and block * ADC-6 · Blank control group ADC-1 ADC-2 7 Figure 5 / 11 WO 2025 / 016453 PCT / CN2024 / 106435 CAL-27 · Blank control group * ADC-1 (6 mina) Instrument and block meaning EGFR +++, HER3 + * ADC-6 ADC-2 anti-EGFR mAb Figure 8 NCI-H1975 (EGFR L858R / T790M) EGFR ++, HER3 + (g mina) Instrument and block self · Blank control group * ADC-2 -·- ADC-4 ADC-5 ADC-6 Days after administration (days) Figure 9 6 / 11 WO 2025 / 016453 PCT / CN202

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