Anti-DLL3 antibody or antigen binding fragment thereof, and use thereof

Abstract

The present invention relates to an anti-DLL3 antibody or an antigen-binding fragment thereof, and the use thereof. The anti-DLL3 antibody or antigen-binding fragment thereof provided by the present invention has high affinity for DLL3, and an ADC drug obtained via conjugation exhibits a good anti-tumor therapeutic effect.

Description

Anti-DLL3 antibodies or antigen-binding fragments thereof and uses thereof Technical Field

[0001] The present invention belongs to the field of biopharmaceuticals and relates to anti-DLL3 antibodies or antigen-binding fragments thereof and their uses. The present invention also relates to nucleic acid molecules encoding the anti-DLL3 antibodies or antigen-binding fragments thereof, vectors and host cells containing the nucleic acid molecules, and pharmaceutical compositions and antibody-drug conjugates containing the anti-DLL3 antibodies or antigen-binding fragments thereof. The present invention further relates to therapeutic uses of the anti-DLL3 antibodies or antigen-binding fragments thereof, pharmaceutical compositions containing the same, and antibody-drug conjugates. Background Art

[0002] Small cell lung cancer (SCLC) accounts for approximately 15% of lung cancer cases, with over 240,000 new cases in my country each year. SCLC is a multifactorial tumor with a complex pathogenesis. The most significant difference between SCLC and NSCLC is that SCLC cells are neuroendocrine, meaning they can receive signals from neurons and release hormones into the bloodstream. SCLC is divided into limited-stage (LS, meaning no distant metastasis) and extensive-stage (ES, meaning distant metastasis). ES-SCLC accounts for two-thirds of cases, with a 5-year survival rate of less than 2%, significantly lower than the 31% 5-year survival rate for LS-SCLC. Treatment of SCLC remains primarily based on radiotherapy and chemotherapy, but the available drugs are limited. Although SCLC is very sensitive to initial treatment, most patients will relapse and metastasize due to drug resistance. Therefore, actively exploring second-line and even third-line treatments for SCLC is particularly important. Over the past three decades, the life expectancy of patients with small cell lung cancer has not improved, leading to the definition of small cell lung cancer as a refractory cancer (PMID: 31383005, J Immunother Cancer. 2019 Aug 5; 7(1): 205). Although new immune checkpoint inhibitors (anti-PD-1 or PD-L1 antibodies) have been approved by the FDA for the treatment of SCLC in recent years, some immune checkpoint inhibitors such as nivolumab have not shown advantages over chemotherapy (PMID: 33539946, Ann Oncol. 2021 May; 32(5): 631-641). The efficacy of immune checkpoint inhibitors depends largely on the infiltration of immune cells and the expression level of PD-L1. The efficacy of immune checkpoint inhibitors in SCLC is relatively low. The objective response rate of nivolumab in the second-line treatment of relapsed SCLC is only 13.7% (PMID: 33539946, Ann Oncol. 2021 May; 32(5): 631-641; PMID: 33065386, Transl Oncol. 2021 Jan; 14(1): 100889). Therefore, it is particularly important to actively explore new and broad-spectrum treatments for SCLC.

[0003] Delta-like protein ligand 3 (DLL3) is a single-pass transmembrane glycoprotein belonging to the DSL (delta, serrate, lag-2) protein family. It is an inhibitory Notch ligand whose expression is directly related to the key neuroendocrine transcription factor ASCL1. It is highly expressed in SCLC but lowly or not expressed in normal tissues. In normal tissues, DLL3 is only expressed in cells of brain tissue and not on the cell surface (PMID: 33203642, Clin Cancer Res. 2021 Mar 1; 27(5): 1526-1537). 85% of SCLC express DLL3 (≥25% of cells are DLL3 positive), and 68% of SCLC express high levels of DLL3 (≥75% of cells are DLL3 positive). Therefore, DLL3 is expected to become a new biomarker and a potential target for small cell lung cancer, and targeting DLL3 may be effective for most SCLC (PMID: 26311731, Sci Transl Med. 2015 Aug 26; 7(302): 302ra136). Not only SCLC, DLL3 is also highly expressed in other neuroendocrine tumors, such as 76.7% of castration-resistant neuroendocrine prostate cancer, 89% of Merkel cell carcinoma and 81% of cervical neuroendocrine carcinoma (PMID: 30894499, Sci Transl Med. 2019 Mar20; 11(484): eaav0891; PMID: 32372416, Oncologist. 2020 Sep; 25(9): 810-817; PMID: 33208671, Appl Immunohistochem Mol Morphol. 2021 Apr 1; ​​29(4): 299-304).

[0004] All the drugs under development globally targeting DLL3 are large molecule drugs, including one in Phase III clinical trials, DLL3-PBD (pyrrolobenzodiazepine) ADC (Rova T, AbbVie), which was terminated in 2020. In a Phase III study of Rova T for the second-line treatment of SCLC (TAHOE study), the overall survival (OS) of the Rova T group was shorter than that of the chemical control group (topotecan group) compared with topotecan. Rova-T uses PBD, which has a strong toxicity, as a toxin, which limits the dosage of Rova-T in clinical trials (0.3 mg / kg), and the clinical toxicity of Rova-T is similar to that of other ADCs using PBD as a toxin. It is speculated that this is related to the premature cleavage of the linker in Rova-T, the premature release of the toxin before endocytosis, and the spread from tumor cells to normal cells (PMID: 33607312, J Thorac Oncol. 2021 Sep; 16(9): 1547-1558). There are two drugs targeting DLL3 in clinical phase I, including a CAR-T and a CD3xDLL3 bispecific antibody (AMG 757). AMG 757 uses the new generation of bispecific antibody technology platform HLE BiTE. The architecture is a tandem scFv\fused Fc in BiTE, and the Fc adopts a single-chain structure connected end to end. AMG 757 is used for the second-line treatment of SCLC and is in the phase I escalation stage. It has good safety and shows certain therapeutic effects (ORR is 16%). In summary, DLL3 is highly expressed in neuroendocrine tumors such as SCLC, and drugs targeting DLL3 are safe and show certain efficacy.

[0005] At present, no research on the DLL3 target has been disclosed in China, and the development of a new generation of anti-DLL3 antibodies has important scientific and application value. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to obtain antibodies that specifically bind to DLL3, especially antibodies with high affinity to human DLL3, through hybridoma screening and humanization technology.

[0007] To address the above technical issues, the present invention aims to provide an anti-DLL3 antibody or antigen-binding fragment thereof that binds to DLL3, and to provide uses thereof based on such an antibody or fragment. The term "fragment" of an antibody molecule as used herein encompasses various functional fragments of an antibody, such as its antigen-binding portion, such as Fab, F(ab')2, or scFv fragments.

[0008] The present invention provides the following technical solutions.

[0009] In a first aspect, the present invention provides an antibody or an antigen-binding fragment thereof targeting DLL3.

[0010] The present invention provides murine anti-DLL3 antibodies, chimeric antibodies, and humanized anti-DLL3 antibodies that specifically bind to DLL3. The anti-DLL3 antibodies of the present invention are expected to have minimal immunogenicity in human subjects and be well tolerated by human subjects.

[0011] The present invention uses DLL3-Fc protein to immunize mice. The anti-DLL3 specific antibodies screened by hybridoma technology have stronger endocytosis efficiency and high affinity with both human and cynomolgus monkey DLL3. The ADC drug obtained by coupling exhibits good anti-tumor efficacy.

[0012] In some embodiments, the present invention provides an anti-DLL3 antibody or antigen-binding fragment thereof that binds DLL3, comprising:

[0013] 1) the three heavy chain CDRs (HCDR1, HCDR2, HCDR3) comprised in the heavy chain variable region as shown in SEQ ID NO: 7, or the three light chain CDRs (LCDR1, LCDR2, LCDR3) comprised in the light chain variable region as shown in SEQ ID NO: 8;

[0014] 2) the three heavy chain CDRs (HCDR1, HCDR2, HCDR3) comprised by the heavy chain variable region as set forth in SEQ ID NO: 21 and / or the three light chain CDRs (LCDR1, LCDR2, LCDR3) comprised by the light chain variable region as set forth in SEQ ID NO: 22;

[0015] 3) the three heavy chain CDRs (HCDR1, HCDR2, HCDR3) contained in the heavy chain variable region as shown in SEQ ID NO: 35 and / or the three light chain CDRs (LCDR1, LCDR2, LCDR3) contained in the light chain variable region as shown in SEQ ID NO: 36.

[0016] Based on the variable region amino acid sequence of a given antibody or fragment thereof of the present invention, those skilled in the art can routinely determine the CDRs contained therein. For example, according to a specific embodiment of the present invention, the Kabat scheme, the AbM scheme, the Chothia scheme or the Contact scheme are used to define the CDRs in the variable region amino acid sequence.

[0017] In some embodiments, the present invention provides an anti-DLL3 antibody or antigen-binding fragment thereof that binds to DLL3, comprising heavy chain variable region CDRs (HCDR1, HCDR2, HCDR3) and / or light chain variable region CDRs (LCDR1, LCDR2, LCDR3), wherein:

[0018] 1) HCDR1 comprises the sequence of SEQ ID NO: 1, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 1, or consists of SEQ ID NO: 1; HCDR2 comprises the sequence of SEQ ID NO: 2, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 2, or consists of SEQ ID NO: 2; HCDR3 comprises the sequence of SEQ ID NO: 3, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 3, or consists of SEQ ID NO: 3; LCDR1 comprises the sequence of SEQ ID NO: 4, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 4, or consists of SEQ ID NO: 4; LCDR2 comprises the sequence of SEQ ID NO: 5, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 5, or consists of SEQ ID NO: NO:5; LCDR3 comprises the sequence shown in SEQ ID NO:6, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:6, or consists of SEQ ID NO:6;

[0019] 2) HCDR1 comprises the sequence of SEQ ID NO: 15, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 15, or consists of SEQ ID NO: 15; HCDR2 comprises the sequence of SEQ ID NO: 16, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 16, or consists of SEQ ID NO: 16; HCDR3 comprises the sequence of SEQ ID NO: 17, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 17, or consists of SEQ ID NO: 17; LCDR1 comprises the sequence of SEQ ID NO: 18, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 18, or consists of SEQ ID NO: 18; LCDR2 comprises the sequence of SEQ ID NO: 19, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: NO: 19 contains one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, or consists of SEQ ID NO: 19; LCDR3 comprises the sequence shown in SEQ ID NO: 20, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof relative to SEQ ID NO: 20, or consists of SEQ ID NO: 20; or

[0020] 3) HCDR1 comprises the sequence of SEQ ID NO: 29, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 29, or consists of SEQ ID NO: 29; HCDR2 comprises the sequence of SEQ ID NO: 30, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 30, or consists of SEQ ID NO: 30; HCDR3 comprises the sequence of SEQ ID NO: 31, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 31, or consists of SEQ ID NO: 31; LCDR1 comprises the sequence of SEQ ID NO: 32, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 32, or consists of SEQ ID NO: 32; LCDR2 comprises the sequence of SEQ ID NO: 33, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: NO:33 contains a sequence of one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, or consists of SEQ ID NO:33; LCDR3 comprises the sequence shown in SEQ ID NO:34, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof relative to SEQ ID NO:34, or consists of SEQ ID NO:34.

[0021] In some embodiments, the present invention provides an anti-DLL3 antibody or antigen-binding fragment thereof that binds DLL3, comprising a heavy chain variable region, wherein:

[0022] 1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 7, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 7, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 7, or consists of SEQ ID NO: 7;

[0023] 2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 9, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 9, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 9, or consists of SEQ ID NO: 9;

[0024] 3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 10, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 10, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 10, or consists of SEQ ID NO: 10;

[0025] 4) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 11, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 11, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 11, or consists of SEQ ID NO: 11;

[0026] 5) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 21, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 21, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 21, or consists of SEQ ID NO: 21;

[0027] 6) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 23, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 23, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 23, or consists of SEQ ID NO: 23;

[0028] 7) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 24, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 24, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 24, or consists of SEQ ID NO: 24;

[0029] 8) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 25, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 25, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 25, or consists of SEQ ID NO: 25;

[0030] 9) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 26, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 26, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 26, or consists of SEQ ID NO: 26;

[0031] 10) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 35, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 35, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 35, or consists of SEQ ID NO: 35;

[0032] 11) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 37, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 37, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 37, or consists of SEQ ID NO: 37;

[0033] 12) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 38, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 38, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 38, or consists of SEQ ID NO: 38;

[0034] 13) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 39, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 39, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 39, or consists of SEQ ID NO: 39;

[0035] 14) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 40, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 40, or consists of SEQ ID NO: 40;

[0036] 15) The heavy chain variable region comprises the amino acid sequence shown in SEQ ID NO:41, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:41, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:41, or consists of SEQ ID NO:41.

[0037] In one embodiment, the invention provides an anti-DLL3 antibody or antigen-binding fragment thereof that binds DLL3, comprising a light chain variable region, wherein:

[0038] 1) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 8, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 8, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 8, or consists of SEQ ID NO: 8;

[0039] 2) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 12, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 12, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 12, or consists of SEQ ID NO: 12;

[0040] 3) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 13, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 13, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 13, or consists of SEQ ID NO: 13;

[0041] 4) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 14, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 14, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 14, or consists of SEQ ID NO: 14;

[0042] 5) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 22, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 22, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 22, or consists of SEQ ID NO: 22;

[0043] 6) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 27, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 27, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 27, or consists of SEQ ID NO: 27;

[0044] 7) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 28, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 28, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 28, or consists of SEQ ID NO: 28;

[0045] 8) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 36, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 36, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 36, or consists of SEQ ID NO: 36;

[0046] 9) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 42, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 42, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 42, or consists of SEQ ID NO: 42;

[0047] 10) the light chain variable region comprises the amino acid sequence of SEQ ID NO: 43, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 43, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 43, or consists of SEQ ID NO: 43; or

[0048] 11) The light chain variable region comprises the amino acid sequence shown in SEQ ID NO:44, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:44, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:44, or consists of SEQ ID NO:44.

[0049] In some embodiments, the present invention provides an anti-DLL3 antibody or antigen-binding fragment thereof that binds to DLL3 comprising a heavy chain variable region and / or a light chain variable region selected from the group consisting of:

[0050] 1) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 7, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 7, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 7, or consists of SEQ ID NO: 7; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 8, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 8, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 8, or consists of SEQ ID NO: 8;

[0051] 2) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 9, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 9, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 9, or consists of SEQ ID NO: 9; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 12, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 12, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 12, or consists of SEQ ID NO: 12;

[0052] 3) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 9, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 9, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 9, or consists of SEQ ID NO: 9; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 13, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 13, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 13, or consists of SEQ ID NO: 13;

[0053] 4) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 9, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 9, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 9, or consists of SEQ ID NO: 9; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 14, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 14, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 14, or consists of SEQ ID NO: 14;

[0054] 5) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 10, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 10, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 10, or consists of SEQ ID NO: 10; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 12, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 12, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 12, or consists of SEQ ID NO: 12;

[0055] 6) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 10, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 10, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 10, or consists of SEQ ID NO: 10; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 13, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 13, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 13, or consists of SEQ ID NO: 13;

[0056] 7) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 10, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 10, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 10, or consists of SEQ ID NO: 10; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 14, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 14, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 14, or consists of SEQ ID NO: 14;

[0057] 8) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 11, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 11, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 11, or consists of SEQ ID NO: 11; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 12, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 12, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 12, or consists of SEQ ID NO: 12;

[0058] 9) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 11, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 11, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 11, or consists of SEQ ID NO: 11; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 13, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 13, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 13, or consists of SEQ ID NO: 13;

[0059] 10) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 11, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 11, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 11, or consists of SEQ ID NO: 11; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 14, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 14, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 14, or consists of SEQ ID NO: 14;

[0060] 11) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 21, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 21, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 21, or consists of SEQ ID NO: 21; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 22, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 22, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 22, or consists of SEQ ID NO: 22;

[0061] 12) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 23, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 23, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 23, or consists of SEQ ID NO: 23; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 28, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 28, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 28, or consists of SEQ ID NO: 28;

[0062] 13) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 35, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 35, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 35, or consists of SEQ ID NO: 35; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 36, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 36, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 36, or consists of SEQ ID NO: 36;

[0063] 14) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 40, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 40, or consists of SEQ ID NO: 40; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 43, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 43, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 43, or consists of SEQ ID NO: 43;

[0064] 15) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 40, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 40, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 40, or consists of SEQ ID NO: 40; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 44, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 44, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 44, or consists of SEQ ID NO: 44;

[0065] 16) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:41, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:41, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:41, or consists of SEQ ID NO:41; the light chain variable region comprises the amino acid sequence of SEQ ID NO:43, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:43, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:43, or consists of SEQ ID NO:43;

[0066] 17) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 23, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 23, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 23, or consists of SEQ ID NO: 23; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 27, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 27, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 27, or consists of SEQ ID NO: 27;

[0067] 18) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 24, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 24, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 24, or consists of SEQ ID NO: 24; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 27, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 27, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 27, or consists of SEQ ID NO: 27;

[0068] 19) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 24, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 24, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 24, or consists of SEQ ID NO: 24; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 28, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 28, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 28, or consists of SEQ ID NO: 28;

[0069] 20) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 25, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 25, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 25, or consists of SEQ ID NO: 25; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 27, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 27, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 27, or consists of SEQ ID NO: 27;

[0070] 21) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 25, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 25, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 25, or consists of SEQ ID NO: 25; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 28, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 28, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 28, or consists of SEQ ID NO: 28;

[0071] 22) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 26, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 26, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 26, or consists of SEQ ID NO: 26; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 27, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 27, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 27, or consists of SEQ ID NO: 27;

[0072] 23) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 26, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 26, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 26, or consists of SEQ ID NO: 26; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 28, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 28, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 28, or consists of SEQ ID NO: 28;

[0073] 24) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 37, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 37, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 37, or consists of SEQ ID NO: 37; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 42, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 42, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 42, or consists of SEQ ID NO: 42;

[0074] 25) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO: 37, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 37, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 37, or consists of SEQ ID NO: 37; the light chain variable region comprises the amino acid sequence of SEQ ID NO: 43, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 43, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 43, or consists of SEQ ID NO: 43;

[0075] 26) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:37, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:37, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:37, or consists of SEQ ID NO:37; the light chain variable region comprises the amino acid sequence of SEQ ID NO:44, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:44, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:44, or consists of SEQ ID NO:44;

[0076] 27) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:38, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:38, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:38, or consists of SEQ ID NO:38; the light chain variable region comprises the amino acid sequence of SEQ ID NO:42, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:42, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:42, or consists of SEQ ID NO:42;

[0077] 28) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:38, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:38, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:38, or consists of SEQ ID NO:38; the light chain variable region comprises the amino acid sequence of SEQ ID NO:43, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:43, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:43, or consists of SEQ ID NO:43;

[0078] 29) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:38, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:38, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:38, or consists of SEQ ID NO:38; the light chain variable region comprises the amino acid sequence of SEQ ID NO:44, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:44, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:44, or consists of SEQ ID NO:44;

[0079] 30) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:39, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:39, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:39, or consists of SEQ ID NO:39; the light chain variable region comprises the amino acid sequence of SEQ ID NO:42, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:42, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:42, or consists of SEQ ID NO:42;

[0080] 31) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:39, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:39, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:39, or consists of SEQ ID NO:39; the light chain variable region comprises the amino acid sequence of SEQ ID NO:43, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:43, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:43, or consists of SEQ ID NO:43;

[0081] 32) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:39, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:39, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:39, or consists of SEQ ID NO:39; the light chain variable region comprises the amino acid sequence of SEQ ID NO:44, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:44, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:44, or consists of SEQ ID NO:44;

[0082] 33) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:40, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:40, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:40, or consists of SEQ ID NO:40; the light chain variable region comprises the amino acid sequence of SEQ ID NO:42, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:42, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:42, or consists of SEQ ID NO:42;

[0083] 34) the heavy chain variable region comprises the amino acid sequence of SEQ ID NO:41, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:41, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:41, or consists of SEQ ID NO:41; the light chain variable region comprises the amino acid sequence of SEQ ID NO:42, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:42, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:42, or consists of SEQ ID NO:42;

[0084] 35) The heavy chain variable region comprises the amino acid sequence as shown in SEQ ID NO:41, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:41, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:41, or consists of SEQ ID NO:41; the light chain variable region comprises the amino acid sequence as shown in SEQ ID NO:44, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO:44, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO:44, or consists of SEQ ID NO:44.

[0085] In some embodiments, the present invention provides an anti-DLL3 antibody or antigen-binding fragment thereof that binds to DLL3, comprising a heavy chain variable region and / or a light chain variable region, wherein:

[0086] 1) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 7, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 8;

[0087] 2) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 9, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 12;

[0088] 3) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 9, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 13;

[0089] 4) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 9, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 14;

[0090] 5) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 10, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 12;

[0091] 6) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 10, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 13;

[0092] 7) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 10, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 14;

[0093] 8) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 11, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 12;

[0094] 9) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 11, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 13;

[0095] 10) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 11, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 14;

[0096] 11) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 21, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 22;

[0097] 12) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 23, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 28;

[0098] 13) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 35, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 36;

[0099] 14) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 40, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 43;

[0100] 15) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 40, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 44;

[0101] 16) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 41, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 43;

[0102] 17) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 23, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 27;

[0103] 18) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 24, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 27;

[0104] 19) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 24, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 28;

[0105] 20) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 25, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 27;

[0106] 21) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 25, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 28;

[0107] 22) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 26, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 27;

[0108] 23) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 26, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 28;

[0109] 24) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 37, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 42;

[0110] 25) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 37, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 43;

[0111] 26) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 37, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 44;

[0112] 27) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 38, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 42;

[0113] 28) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 38, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 43;

[0114] 29) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 38, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 44;

[0115] 30) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 39, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 42;

[0116] 31) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 39, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 43;

[0117] 32) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 39, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 44;

[0118] 33) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 40, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 42;

[0119] 34) the heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 41, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO: 42; or

[0120] 35) The heavy chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO:41, and the light chain variable region comprises or consists of the amino acid sequence shown in SEQ ID NO:44.

[0121] In particular, the antibodies or antigen-binding fragments thereof of the present invention comprise at least a heavy chain variable region and a light chain variable region, both of which include the above-mentioned CDRs and a framework region (FR) between them, and the arrangement of each domain is: FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4. Further optionally, the "at least 90% identity" resulting in a maximum of 10% difference in amino acid sequence may exist in any framework region in the heavy chain variable region or the light chain variable region, or in any domain or sequence other than the heavy chain variable region and the light chain variable region in the antibodies or fragments thereof of the present invention. The difference may be caused by amino acid substitution, deletion or insertion at any position.

[0122] In some embodiments, the antibody or its antigen-binding fragment further comprises a human or mouse constant region, preferably a human or mouse heavy chain constant region and / or a light chain constant region; preferably, the antibody or its antigen-binding fragment comprises an IgG, IgA, IgM, IgD or IgE heavy chain constant region and / or a κ or λ type light chain constant region.

[0123] In some embodiments, the antibody or antigen-binding fragment thereof further comprises a heavy chain and / or light chain constant region sequence derived from a human antibody germline consensus sequence. In some embodiments, the heavy chain constant region is preferably derived from a constant region sequence of human IgG1, IgG2, IgG3, or IgG4. In a specific embodiment, the heavy chain constant region comprises or consists of the amino acid sequence set forth in SEQ ID NO: 45. In a specific embodiment, the light chain constant region comprises or consists of the amino acid sequence set forth in SEQ ID NO: 46.

[0124] It will be appreciated that sequence variants of these constant region domains may also be used, for example comprising one or more amino acid modifications, wherein the amino acid positions are identified by the EU index system of Kabat et al. (1991).

[0125] In a specific embodiment, the present invention provides an anti-DLL3 antibody or antigen-binding fragment thereof that binds to DLL3, comprising a heavy chain and / or a light chain, wherein:

[0126] 1) the heavy chain comprises the amino acid sequence of SEQ ID NO: 47, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 47, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 47, or consists of SEQ ID NO: 47; the light chain comprises the amino acid sequence of SEQ ID NO: 48, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 48, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 48, or consists of SEQ ID NO: 48;

[0127] 2) the heavy chain comprises the amino acid sequence of SEQ ID NO: 47, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 47, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 47, or consists of SEQ ID NO: 47; the light chain comprises the amino acid sequence of SEQ ID NO: 49, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 49, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 49, or consists of SEQ ID NO: 49;

[0128] 3) the heavy chain comprises the amino acid sequence of SEQ ID NO: 47, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 47, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 47, or consists of SEQ ID NO: 47; the light chain comprises the amino acid sequence of SEQ ID NO: 50, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 50, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 50, or consists of SEQ ID NO: 50;

[0129] 4) the heavy chain comprises the amino acid sequence of SEQ ID NO:51, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:51, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:51, or consists of SEQ ID NO:51; the light chain comprises the amino acid sequence of SEQ ID NO:48, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:48, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:48, or consists of SEQ ID NO:48;

[0130] 5) the heavy chain comprises the amino acid sequence of SEQ ID NO:51, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:51, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:51, or consists of SEQ ID NO:51; the light chain comprises the amino acid sequence of SEQ ID NO:49, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:49, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:49, or consists of SEQ ID NO:49;

[0131] 6) the heavy chain comprises the amino acid sequence of SEQ ID NO:51, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:51, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:51, or consists of SEQ ID NO:51; the light chain comprises the amino acid sequence of SEQ ID NO:50, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO:50, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO:50, or consists of SEQ ID NO:50;

[0132] 7) the heavy chain comprises the amino acid sequence of SEQ ID NO: 52, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 52, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 52, or consists of SEQ ID NO: 52; the light chain comprises the amino acid sequence of SEQ ID NO: 48, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 48, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 48, or consists of SEQ ID NO: 48;

[0133] 8) the heavy chain comprises the amino acid sequence of SEQ ID NO: 52, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 52, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 52, or consists of SEQ ID NO: 52; the light chain comprises the amino acid sequence of SEQ ID NO: 49, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 49, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 49, or consists of SEQ ID NO: 49;

[0134] 9) the heavy chain comprises the amino acid sequence of SEQ ID NO: 52, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 52, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 52, or consists of SEQ ID NO: 52; the light chain comprises the amino acid sequence of SEQ ID NO: 50, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 50, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 50, or consists of SEQ ID NO: 50;

[0135] 10) the heavy chain comprises the amino acid sequence of SEQ ID NO: 53, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 53, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 53, or consists of SEQ ID NO: 53; the light chain comprises the amino acid sequence of SEQ ID NO: 54, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 54, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 54, or consists of SEQ ID NO: 54;

[0136] 11) the heavy chain comprises the amino acid sequence of SEQ ID NO: 55, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 55, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 55, or consists of SEQ ID NO: 55; the light chain comprises the amino acid sequence of SEQ ID NO: 56, or a sequence containing one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 56, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 56, or consists of SEQ ID NO: 56;

[0137] 12) the heavy chain comprises the amino acid sequence of SEQ ID NO: 57, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 57, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 57, or consists of SEQ ID NO: 57; the light chain comprises the amino acid sequence of SEQ ID NO: 58, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions, or insertions, or any combination thereof, relative to SEQ ID NO: 58, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the amino acid sequence of SEQ ID NO: 58, or consists of SEQ ID NO: 58; or

[0138] 13) The heavy chain comprises the amino acid sequence of SEQ ID NO: 55, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 55, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 55, or consists of SEQ ID NO: 55; the light chain comprises the amino acid sequence of SEQ ID NO: 58, or a sequence comprising one or more amino acid substitutions (e.g., conservative substitutions), deletions or insertions, or any combination thereof, relative to SEQ ID NO: 58, or an amino acid sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or 99% identical to the amino acid sequence of SEQ ID NO: 58, or consists of SEQ ID NO: 58.

[0139] In certain embodiments of any of the aforementioned antibodies, the antibody or antigen-binding fragment thereof is an anti-DLL3 antibody or antigen-binding fragment thereof; preferably, the antibody is in any form, such as a monoclonal antibody, a single-chain antibody, a bifunctional antibody, a single-domain antibody, a nanobody, a fully or partially humanized antibody, or a chimeric antibody. In a specific embodiment, the antibody is a monoclonal antibody. In a preferred embodiment, the antibody is a chimeric antibody. In another more preferred embodiment, the antibody is a humanized antibody.

[0140] In certain embodiments of the antibody of any of the foregoing, the antibody is a full-length antibody.

[0141] In some embodiments, the anti-DLL3 antibodies of the present invention are intact antibodies, such as IgG1, IgG2, IgG3, or IgG4 antibodies. In another embodiment, the anti-DLL3 antibodies of the present invention encompass only antigen-binding portions thereof, such as Fab, Fab', Fab'-SH, (Fab')2, Fv, scFv, BsFv, dsFv, or (dsFv)2 fragments.

[0142] In some embodiments, the antigen-binding fragment is an antigen-binding fragment of an antibody or half antibody, such as Fab, Fab', Fab'-SH, (Fab')2, Fv, scFv, BsFv, dsFv or (dsFv)2 fragment; more preferably, the antibody is IgG.

[0143] In a second aspect, the present invention provides a nucleic acid molecule encoding any of the antibodies or antigen-binding fragments thereof described in the first aspect, or encoding the heavy chain CDRs, light chain CDRs, heavy chain variable regions, light chain variable regions, heavy chains, or light chains contained in the antibodies or antigen-binding fragments thereof. In some embodiments, the nucleic acid molecule may be an isolated nucleic acid molecule.

[0144] The nucleic acid molecules of the present invention can be cloned into vectors and then transformed or transfected into host cells. Therefore, in a third aspect, the present invention provides vectors comprising the nucleic acid molecules of the second aspect. In one embodiment, the vector is an expression vector, such as a eukaryotic expression vector, a prokaryotic expression vector, an artificial chromosome, and a phage vector.

[0145] The vector or nucleic acid molecule of the present invention can be used for transforming or transfecting host cells for purposes such as preservation or antibody expression. Therefore, in a fourth aspect, the present invention provides a host cell comprising the vector of the third aspect or the nucleic acid molecule of the second aspect, or the host cell is transformed or transfected by the nucleic acid molecule and / or vector of the present invention. The host cell can be any prokaryotic or eukaryotic cell, such as a bacterium or insect, fungi, plant or animal cell. In some embodiments, the host cell is prokaryotic, such as Escherichia coli. In other embodiments, the host cell is eukaryotic, such as 293 cells, Chinese hamster ovary celI, yeast cell, or plant cell. In some embodiments, the host cell is other cells suitable for preparing antibodies or their antigen-binding fragments.

[0146] The antibodies or antigen-binding fragments thereof provided herein can be obtained using any method known in the art. For example, the heavy chain variable region and / or light chain variable region of the antibody, or the heavy chain and / or light chain of the antibody, can be first obtained from the nucleic acid molecules provided herein, and then assembled with any other domains of the antibody to form an antibody. Alternatively, in a fifth aspect, the present invention provides a method for preparing the anti-DLL3 antibodies or antigen-binding fragments thereof described herein, comprising expressing the antibody or antigen-binding fragment thereof in a host cell described herein under conditions suitable for expression of the antibody or antigen-binding fragment thereof, and recovering the expressed antibody or antigen-binding fragment thereof from the host cell.

[0147] In a sixth aspect, the present invention provides a conjugate comprising the antibody or antigen-binding fragment thereof of the present invention and a coupling portion, wherein the coupling portion is another molecule; preferably, the coupling portion is a radioactive isotope, a fluorescent substance, a luminescent substance, a colored substance, an enzyme or a chemical drug, etc.

[0148] The antibody or its antigen-binding fragment, nucleic acid molecule, vector, host cell and / or conjugate provided by the present invention can be included in a pharmaceutical composition, more particularly included in a pharmaceutical preparation, so as to be used for various purposes according to actual needs. Therefore, in a seventh aspect, the present invention provides a pharmaceutical composition comprising the antibody or its antigen-binding fragment of the first aspect of the present invention or the nucleic acid molecule, vector, host cell, conjugate and pharmaceutically acceptable carrier of the present invention. In some embodiments of the present invention, the pharmaceutical composition further comprises a second therapeutic agent and / or optionally a pharmaceutical excipient, the second therapeutic agent being selected from cytokines, antibodies, chemotherapeutic agents and small molecule drugs.

[0149] In an eighth aspect, the present invention provides an antibody-drug conjugate (ADC), comprising the antibody or antigen-binding fragment thereof according to the first aspect of the present invention, the antibody-drug conjugate further comprising a cytotoxic drug and a linker connecting the antibody or antigen-binding fragment thereof according to the first aspect of the present invention to the cytotoxic drug. The cytotoxic drug is selected from DX8951, MMAE, or Dxd, and the linker is a cleavable linker.

[0150] In a ninth aspect, the present invention provides use of an anti-DLL3 antibody or antigen-binding fragment thereof, or a nucleic acid molecule, vector, host cell, conjugate, pharmaceutical composition, or antibody-drug conjugate of the present invention, in the preparation of a medicament for treating a disease suffered by a subject.

[0151] In one embodiment, any of the antibodies or antigen-binding fragments thereof described in the first aspect, or the antibody-drug conjugates described in the eighth aspect, are used to treat an autoimmune disease or cancer. Furthermore, the disease is a DLL3-positive cancer. In one embodiment, the disease is, for example, a neuroendocrine tumor, lung cancer, prostate cancer, melanoma, or gastric cancer. Preferably, the lung cancer is small cell lung cancer, and the neuroendocrine tumor is castration-resistant neuroendocrine prostate cancer, large cell neuroendocrine carcinoma, or gastroenteropancreatic neuroendocrine tumor.

[0152] In a tenth aspect, the present invention provides a method for preventing and / or treating a disease in a subject, the method comprising administering to a subject in need thereof an effective amount of the antibody or antigen-binding fragment thereof, or the nucleic acid molecule, vector, host cell, conjugate, pharmaceutical composition, and / or antibody-drug conjugate of the present invention. The disease comprises a tumor or an autoimmune disease; preferably, the subject is a mammal; more preferably, the subject is a human.

[0153] In some embodiments, the disease comprises a tumor or an autoimmune disease. Furthermore, the disease is a DLL3-positive autoimmune disease or a DLL3-positive cancer. In one embodiment, the disease is, for example, a neuroendocrine tumor, lung cancer, prostate cancer, melanoma, or gastric cancer. Preferably, the lung cancer is small cell lung cancer, and the neuroendocrine tumor is castration-resistant neuroendocrine prostate cancer, large cell neuroendocrine carcinoma, or gastroenteropancreatic neuroendocrine tumor.

[0154] In some embodiments, the present invention provides an antibody or antigen-binding fragment thereof disclosed herein or a nucleic acid molecule, vector, host cell, conjugate, pharmaceutical composition or antibody-drug conjugate of the present invention for use as a medicament.

[0155] In some embodiments, the present invention provides an antibody or antigen-binding fragment thereof disclosed herein or a nucleic acid molecule, vector, host cell, conjugate, pharmaceutical composition or antibody-drug conjugate of the present invention for use in therapy.

[0156] In an eleventh aspect, the present invention provides a kit comprising the antibody or antigen-binding fragment or conjugate thereof of the present invention.

[0157] In a twelfth aspect, the present invention provides a method for detecting the presence or level of DLL3 in a sample, comprising the steps of contacting the antibody or antigen-binding fragment or conjugate of the present invention with the sample, and detecting whether the antibody or antigen-binding fragment or conjugate forms a complex with DLL3.

[0158] The present invention is further illustrated in the following drawings and specific embodiments. However, these drawings and specific embodiments should not be considered to limit the scope of the present invention, and changes that are readily apparent to those skilled in the art will be included within the spirit of the present invention and the protection scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0159] FIG1 is a graph showing the nonspecific binding activity of anti-DLL3 mouse monoclonal antibodies to human DLL1 protein.

[0160] FIG2 is a graph showing the non-specific binding activity of anti-DLL3 mouse monoclonal antibodies to human DLL4 protein.

[0161] FIG3 is a killing curve of anti-DLL3 humanized antibody-ADC on HEK293-cynoDLL3 cells.

[0162] FIG4 is a killing curve of anti-DLL3 humanized antibody-ADC on NCI-H524 cells.

[0163] FIG5 is a graph showing the inhibition of NCI-H524 tumor cell growth by anti-DLL3 humanized antibody ADC.

[0164] FIG6 is a graph showing the rate of change in mouse body weight in the NCI-H524 tumor model inhibited by anti-DLL3 humanized antibody ADC. DETAILED DESCRIPTION

[0165] All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. In addition, the materials, methods and examples described herein are illustrative only and are not intended to be limiting. Other features, objects and advantages of the present invention will be apparent from this specification and the accompanying drawings and from the appended claims. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art. For the purposes of the present invention, the following terms are defined below.

[0166] definition

[0167] The practice of the present invention will employ, unless otherwise indicated, conventional techniques of molecular biology (including recombinant techniques), microbiology, cell biology, biochemistry and immunology, which are within the skill of the art.

[0168] The term "about" when used in conjunction with a numerical value is meant to encompass the numerical value within a range having a lower limit that is 5% less than the specified numerical value and an upper limit that is 5% greater than the specified numerical value.

[0169] 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.

[0170] As used herein, the term "comprises" or "includes" means including the stated elements, integers or steps, but does not exclude any other elements, integers or steps. In this article, when the term "comprises" or "includes" is used, unless otherwise indicated, it also covers the situation consisting of the stated elements, integers or steps.

[0171] The term "antibody" is used herein in the broadest sense to refer to a protein that contains an antigen binding site.

[0172] The term "immunoglobulin" refers to a protein with the structure of a naturally occurring antibody and is generally used interchangeably with the term "antibody" in this application. IgG immunoglobulins are heterotetrameric glycoproteins consisting of two light chains and two heavy chains bonded by disulfide bonds. From the N-terminus to the C-terminus, each immunoglobulin heavy chain has a heavy chain variable region (VH), also known as a heavy chain variable domain, followed by three heavy chain constant domains (CH1, CH2, and CH3). Similarly, from the N-terminus to the C-terminus, each immunoglobulin light chain has a light chain variable region (VL), also known as a light chain variable domain, followed by a light chain constant domain (CL). In IgG molecules, the VH-CH1 of the heavy chain is usually paired with the VL-CL of the light chain to form a Fab fragment that specifically binds to the antigen. Therefore, an IgG immunoglobulin is essentially composed of two Fab molecules connected by the immunoglobulin hinge region and two dimerized Fc regions. The heavy chains of immunoglobulins can be assigned to one of five classes, called α (IgA), δ (IgD), ε (IgE), γ (IgG), or μ (IgM), based on the type of their constant region, some of which can be further divided into subclasses, such as γ1 (IgG1), γ2 (IgG2), γ3 (IgG3), γ4 (IgG4), α1 (IgA1), and α2 (IgA2). The light chains of immunoglobulins can also be assigned to one of two types, called κ and λ, based on the amino acid sequence of their constant domains.

[0173] The terms "DLL3" and "Delta-like ligand 3" herein refer to any naturally occurring DLL3 produced by expression of DLL3 in a cell. Unless otherwise indicated, the terms include DLL3 from any vertebrate source, such as mammals, such as primates (e.g., humans and cynomolgus monkeys) and rodents (e.g., mice and rats).

[0174] "Complementarity determining regions" or "CDR regions" or "CDRs" or "hypervariable regions" are regions of an antibody variable domain that are highly variable in sequence and form structurally defined loops ("hypervariable loops") and / or contain antigen-contacting residues ("antigen contact points"). CDRs are primarily responsible for binding to antigenic epitopes.

[0175] A variety of methods are known in the art for determining CDR sequences within a given VH or VL amino acid sequence: Kabat complementarity determining regions (CDRs) are determined based on sequence variability and are the most commonly used (Kabat et al., Sequences of Proteins of Immunological Interest, 5th Edition, Public Health Service, National Institutes of Health, Bethesda, Md. (1991)), while Chothia refers to the positions of structural loops (Chothia et al., (1987) J. Mol. Biol. 196: 901-917; Chothia et al. (1989) Nature 342: 877-883). AbM CDRs are a compromise between Kabat CDRs and Chothia structural loops and are used by Oxford Molecular's AbM antibody modeling software. "Contact" CDRs are based on analysis of available complex crystal structures. The residues for each of these CDRs, according to the different CDR determination methods, are described below.

[0176] When referring to antibodies defined by specific CDR sequences defined herein, the scope of said antibodies also encompasses antibodies whose variable region sequences comprise said specific CDR sequences, but whose declared CDR boundaries differ from the specific CDR boundaries defined herein due to the application of a different scheme (e.g., a different assignment system rule or combination).

[0177] The CDRs of the antibodies of the present invention can be manually assessed to determine their boundaries according to any protocol or combination thereof in the art. Unless otherwise indicated, in the present invention, the term "CDR" or "CDR sequence" encompasses CDR sequences determined in any of the above ways.

[0178] The terms "antigen binding site" and "antigen binding domain" are used interchangeably to refer to the region of an antibody molecule that actually binds to an antigen. Antigen binding sites include, but are not limited to, Fv, Fab fragments, Fab', Fab'-SH, F(ab')2, single-chain antibody molecules (e.g., scFv), VHH, and other formats.

[0179] The term "variable region" or "variable domain" of an antibody refers to the domain of the antibody heavy chain or light chain that is involved in binding the antibody to the antigen. The variable region of an antibody can be further divided into hypervariable regions (i.e., complementary determining regions (CDRs)) and relatively conserved regions (i.e., framework regions (FRs)) interposed between the hypervariable regions. In the case of IgG immunoglobulins, the heavy chain variable region or light chain variable region comprises FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4, respectively, from N-terminus to C-terminus. In the case of heavy chain antibodies (also referred to herein as nanobodies), for example, heavy chain antibodies from Camelidae, the antigen binding site is composed of a single VH domain (i.e., "VHH" domain). The VHH of a natural heavy chain antibody has a similar structure to the heavy chain variable region of a natural IgG antibody, i.e., comprises four conserved framework regions (FRs) and three complementary determining regions (CDRs).

[0180] "Heavy chain constant region domain" or "heavy chain constant region" refers to a constant region domain from, obtained from, or derived from an immunoglobulin heavy chain, comprising heavy chain constant regions CH1, CH2, CH3, and optionally heavy chain constant region CH4 covalently linked sequentially from N-terminus to C-terminus. In most cases, the heavy chain constant regions CH1 and CH2 are connected by a heavy chain hinge region, but may also be connected by a flexible linker when appropriate.

[0181] The term "EC 50 ”, also known as the “half-maximal effective concentration”, is the concentration of a drug, antibody, or toxic agent that induces a response that is 50% between baseline and maximum after a specified exposure time.

[0182] As used herein, the term "binding" or "specific binding" means that the binding is selective for the antigen and can be distinguished from unwanted or non-specific interactions. The ability of an antigen binding site to bind to a specific antigen can be determined by enzyme-linked immunosorbent assay (ELISA) or conventional binding assays known in the art.

[0183] "Affinity" or "binding affinity" refers to the intrinsic binding ability that reflects the interaction between members of a binding pair. The affinity of a molecule X for its binding partner Y can be expressed by the equilibrium dissociation constant (KD), which is a function of the dissociation rate constant and the association rate constant (kD, respectively). dis and k on Binding affinity can be measured by common methods known in the art.

[0184] Amino acid mutations can be amino acid substitutions, deletions, insertions, and / or additions. In some embodiments, amino acid mutations are substitutions of one or more amino acids, such as single amino acid substitutions or combinations of multiple amino acid substitutions. Amino acid deletions and insertions include deletions and insertions at the amino and / or carboxyl termini of a polypeptide sequence, as well as deletions and insertions within the polypeptide sequence. Amino acid substitutions of the present invention optionally include conservative amino acid substitutions.

[0185] "Percent (%) identity" of an amino acid sequence refers to the percentage of amino acid residues in the candidate sequence that are identical to the amino acid residues in the specific amino acid sequence set forth in this specification, after aligning the candidate sequence with the specific amino acid sequence set forth in this specification and introducing gaps, if necessary, to achieve the maximum percentage identity, and not considering any conservative substitutions as part of the sequence identity. In some embodiments, the present invention contemplates variants of the antibody molecules of the invention that have a substantial degree of identity, e.g., at least 80%, 85%, 90%, 95%, 97%, 98% or 99% or more, relative to the antibody molecules and sequences thereof specifically disclosed herein. The variants may comprise conservative modifications.

[0186] With respect to polypeptide sequences, "conservative modifications" include substitutions, deletions, or additions to a polypeptide sequence that result in the substitution of an amino acid with a chemically similar amino acid. Conservative substitution tables providing functionally similar amino acids are well known in the art. Such conservatively modified variants are in addition to and do not exclude the polymorphic variants, interspecies homologs, and alleles of the present invention. The following eight groups contain amino acids that are conservative substitutions for each other: 1) Alanine (A), Glycine (G); 2) Aspartic Acid (D), Glutamic Acid (E); 3) Asparagine (N), Glutamine (Q); 4) Arginine (R), Lysine (K); 5) Isoleucine (I), Leucine (L), Methionine (M), Valine (V); 6) Phenylalanine (F), Tyrosine (Y), Tryptophan (W); 7) Serine (S), Threonine (T); and 8) Cysteine ​​(C), Methionine (M) (see, e.g., Creighton, Proteins (1984)). In some embodiments, the term "conservative sequence modifications" is used to refer to amino acid modifications that do not significantly affect or alter the binding characteristics of the antibody containing the amino acid sequence.

[0187] The terms "individual" or "subject" are used interchangeably and refer to mammals. Mammals include, but are not limited to, domesticated animals (e.g., cows, sheep, cats, dogs, and horses), primates (e.g., humans and non-human primates such as monkeys), rabbits, and rodents (e.g., mice and rats). In particular, the individual is a human.

[0188] The term "treatment" refers to a clinical intervention intended to alter the natural course of a disease in the individual being treated. Desired therapeutic effects include, but are not limited to, preventing the onset or recurrence of the disease, alleviating symptoms, reducing any direct or indirect pathological consequences of the disease, preventing metastasis, reducing the rate of disease progression, ameliorating or palliating the disease state, and alleviating or improving prognosis. In some embodiments, the antibody molecules of the present invention are used to delay the development of the disease or to slow the progression of the disease.

[0189] The term "prevent" includes the inhibition of the development or progression of a disease or condition or symptoms of a particular disease or condition. In some embodiments, subjects with a family history of cancer are candidates for a preventative regimen. Generally, in the context of cancer, the term "prevent" refers to the administration of a drug before the development of signs or symptoms of cancer, particularly in a subject at risk for cancer.

[0190] The term "effective amount" refers to an amount or dosage of an antibody or composition of the present invention that produces the desired effect in a patient in need of treatment or prevention after administration to the patient in a single or multiple doses. The effective amount can be readily determined by the attending physician, who is skilled in the art, by considering a variety of factors such as the species of the mammal; weight, age, and general health; the specific disease involved; the extent or severity of the disease; the response of the individual patient; the specific antibody administered; the mode of administration; the bioavailability characteristics of the administered formulation; the selected dosing regimen; and the use of any concomitant therapy.

[0191] The term "therapeutically effective amount" refers to an amount that is effective to achieve the desired therapeutic outcome at the desired dosage and for the desired period of time. The therapeutically effective amount of an antibody or antibody fragment or composition can vary depending on factors such as the disease state, the age, sex, and weight of the individual, and the ability of the antibody or antibody portion to stimulate the desired response in the individual. A therapeutically effective amount is also an amount in which any toxic or deleterious effects of the antibody or antibody fragment or composition are outweighed by the therapeutically beneficial effects. A "therapeutically effective amount" preferably inhibits a measurable parameter by at least about 20%, more preferably at least about 40%, even more preferably at least about 50%, 60%, or 70%, and still more preferably at least about 80% or 90%, relative to an untreated subject.

[0192] The term "prophylactically effective amount" refers to an amount effective to achieve the desired preventive result at the required dosage and for the required period of time. Typically, a prophylactic effective amount will be less than a therapeutically effective amount because a prophylactic dose is used in a subject prior to or at an earlier stage of disease.

[0193] The term "pharmaceutical composition" refers to a composition that is in a form that allows the biological activity of the active ingredient contained therein to be effective and does not contain additional ingredients that are unacceptably toxic to the subject to which the composition is administered. The pharmaceutical composition includes, but is not limited to, carriers, diluents, adjuvants, excipients, preservatives, fillers, disintegrants, wetting agents, emulsifiers, suspending agents, sweeteners, flavoring agents, fragrances, antibacterial agents, antifungal agents, lubricants, dispersants, temperature-sensitive materials, temperature regulators, adhesives, stabilizers, suspending agents, etc.

[0194] The term "antibody-drug conjugate (ADC)" refers to a small molecule drug with biological activity connected to an antibody through a chemical link. The antibody acts as a carrier to transport the small molecule drug into target cells.

[0195] Polynucleotides, vectors and hosts

[0196] The present invention provides nucleic acid molecules encoding any of the above-mentioned antibody molecules or antigen-binding fragments thereof. Polynucleotide sequences encoding the antibody molecules or antigen-binding fragments thereof of the present invention can be generated by de novo solid-phase DNA synthesis or genetic engineering methods using methods well known in the art. In addition, the polynucleotides and nucleic acids of the present invention may include a segment encoding a secretory signal peptide, which can be operably linked to the segment encoding the antibody molecules or antigen-binding fragments thereof of the present invention, thereby directing the secretory expression of the antibody molecules or antigen-binding fragments thereof of the present invention.

[0197] The present invention also provides vectors comprising nucleic acid molecules of the present invention. In one embodiment, the vector is an expression vector, such as a eukaryotic expression vector and a prokaryotic expression vector. "Expression vector" refers to a vector comprising a recombinant polynucleotide, which comprises an expression control sequence operatively linked to the nucleotide sequence to be expressed. The expression vector comprises sufficient cis-acting elements for expression; other elements for expression can be provided by the host cell or in an in vitro expression system. Expression vectors include all those known in the art, including cosmids, plasmids (e.g., naked or contained in liposomes) and viruses (e.g., lentiviruses, retroviruses, adenoviruses, and adeno-associated viruses) incorporated into the recombinant polynucleotide.

[0198] The present invention also provides prokaryotic and eukaryotic host cells comprising the nucleic acid molecules or the vectors. Host cells include "transformants" and "transformed cells," which include primary transformed cells and progeny derived therefrom. Host cells are any type of cell system that can be used to produce the antibody molecules of the present invention, including eukaryotic cells, for example, mammalian cells, insect cells, yeast cells; and prokaryotic cells, for example, E. coli cells. Host cells include cultured cells, as well as cells within transgenic animals, transgenic plants, or cultured plant tissues or animal tissues. Host cells suitable for replicating and supporting the expression of the antibody molecules of the present invention or their antigen-binding fragments are well known in the art. Such cells can be transfected or transduced with specific expression vectors, and large quantities of vector-containing cells can be grown for inoculation of large-scale fermenters, thereby obtaining sufficient amounts of antibody molecules.

[0199] Pharmaceutical compositions and pharmaceutical preparations

[0200] The present invention also includes compositions (including pharmaceutical compositions or pharmaceutical preparations) comprising the antibody molecules of the present invention or their antigen-binding fragments and compositions comprising nucleic acid molecules encoding the antibody molecules of the present invention or their antigen-binding fragments. These compositions may also optionally contain suitable pharmaceutical excipients, such as pharmaceutical carriers and pharmaceutical excipients known in the art, including buffers.

[0201] The pharmaceutical composition or preparation of the present invention may also comprise one or more other active ingredients or be used in combination with one or more other active ingredients. The active ingredients are required for the specific indication being treated, preferably having those active ingredients that do not adversely affect the complementary activities of each other. For example, it is desirable to also provide other active ingredients for the treatment of autoimmune diseases, which are suitably combined in an amount effective for the intended use.

[0202] Treatment methods and uses

[0203] As used herein, the terms "individual" or "subject" are used interchangeably to refer to mammals. Mammals include, but are not limited to, domesticated animals (e.g., cows, sheep, cats, dogs, and horses), primates (e.g., humans and non-human primates such as monkeys), rabbits, and rodents (e.g., mice and rats). In particular, the subject is a human.

[0204] In one embodiment, the present invention provides a method for treating a disease in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of an antibody or antigen-binding fragment thereof, or a nucleic acid molecule, vector, host cell, conjugate, pharmaceutical composition, or antibody-drug conjugate of the present invention. In one embodiment, the disease is an autoimmune disease or cancer. Further, the disease is a DLL3-positive cancer. In one embodiment, the disease is, for example, a neuroendocrine tumor, lung cancer, prostate cancer, melanoma, gastric cancer, or the like. Preferably, the lung cancer is small cell lung cancer, and the neuroendocrine tumor is castration-resistant neuroendocrine prostate cancer, large cell neuroendocrine carcinoma, gastroenteropancreatic neuroendocrine tumor, or the like.

[0205] The antibody molecule of the present invention or its antigen-binding fragment (and pharmaceutical composition comprising it) can be administered by any suitable method, including parenteral administration, intrapulmonary administration and intranasal administration, and, if local treatment needs, intralesional administration. Parenteral infusion includes intramuscular, intravenous, intraarterial, intraperitoneal or subcutaneous administration. To a certain extent, it is short-term or long-term according to the medication, and can be administered by any suitable route, for example, by injection, such as intravenous or subcutaneous injection. Various medication schedules are contemplated herein, including, but not limited to, single administration or multiple administrations at multiple time points, push administration and pulse infusion.

[0206] For the prevention or treatment of disease, the appropriate dosage of the antibody molecules of the invention or antigen-binding fragments thereof (when used alone or in combination with one or more other therapeutic agents) will depend on the type of disease being treated, the severity and course of the disease, whether administration is for preventive or therapeutic purposes, previous therapy, the patient's clinical history, and the judgment of the attending physician.

[0207] The following examples are described to assist understanding of the present invention. The examples are not intended to, and should not be interpreted in any way as, limiting the scope of protection of the present invention.

[0208] Example

[0209] The experimental methods described in the following examples, unless otherwise specified, are conventional methods in the art using default parameters and procedures. The experimental materials used, unless otherwise specified, are all commercially available products. Where specific techniques or conditions are not specified in the examples, the experiments were performed according to those described in the literature in the art or in accordance with the instructions of the corresponding products. Where the manufacturer of the reagents or instruments is not specified, all are conventional products that can be purchased through regular channels.

[0210] Example 1: Producing mouse hybridomas against human DLL3

[0211] Mice were immunized with DLL3-Fc protein (Acro#DL3-H5255), SP2 / 0 cells were fused, and positive clones were screened by ELISA.

[0212] The specific method is as follows:

[0213] Animal Immunization: Female Balb / c and SJL (SLAC) mice, 6-8 weeks old, were immunized intraperitoneally with DLL3-hFc protein as the immunogen. The initial immunization was 50 μg / mouse emulsified with Complete Freund's Adjuvant (Sigma F5581), and the booster immunization was 25 μg / mouse emulsified with Incomplete Freund's Adjuvant (Sigma F5506). The interval between the initial and first booster immunizations was typically two weeks, and the interval between the first and second and subsequent booster immunizations was three weeks. Ten days after the final immunization, 25 μg / mouse of DLL3-hFc protein was injected intraperitoneally without adjuvant for a pulse immunization. Three days later, spleens were harvested for cell fusion.

[0214] Cell fusion and selective culture of hybridoma cells: Mouse spleen cells and SP2 / 0 cells (ATCC No. CRL-1581) were electrofused at a 2:1 ratio (BTX electrofusion instrument: ECM2001+) and cultured in 96-well culture plates in HAT medium (Sigma-Aldrich, Catalog No. H0262). After 10 days, hybridoma cell supernatants were screened for antibodies.

[0215] Screening procedure for positive clones: Collect the cultured cell supernatant and perform an ELISA binding assay. Select the positive wells in the cell culture supernatant and culture them in 96-well culture plates using HT medium (Sigma-Aldrich, Catalog No.: H0137) for cloning. After 7-10 days, visible clones will appear, and the supernatant will be collected for antibody detection. Observe under an inverted microscope and select positive wells with only single clones. Expand the culture and freeze. After culturing in serum-free medium (SFM, Thermo, 12045076), collect the supernatant and purify it for subsequent testing.

[0216] ELISA binding assay:

[0217] The supernatant, positive control (fused mouse serum or Rovalpituzumab-mIgG), or negative control (HAT medium or mIgG) were plated in a 96-well flat-bottom detection plate (Corning, 9018) coated with hDLL3-His (Acro, DL3-H52H4) or cynoDLL3-his (Acro, DL3-C52H3), with 50 μL per well. The plates were incubated in a 37°C carbon dioxide incubator for 60 minutes, removed, and washed three times with PBST. Secondary antibody (Anti-Mouse IgG (Fc specific)-Peroxidase antibody produced in goat, Sigma, A0168) was added, and the plates were incubated in a 37°C carbon dioxide incubator for 30 minutes. The plates were removed and washed three times with PBST. TMB (hDLL3 detection: Huzhou Yingchuang Biotechnology Co., Ltd., TMB-S-003; cynoDLL3 detection: Beyotime, P0209) was added at 100 μL per well and color was developed for 15 minutes. Stop solution (hDLL3 detection: sulfuric acid, cynoDLL3 detection: Solarbio, C1058) was added to terminate the reaction at 50 μL per well. The OD value was read. The results are shown in Table 1.

[0218] Table 1 OD values ​​of positive clone hybridoma supernatants binding to hDLL3 and cynoDLL3 proteins

[0219] Note: The ELISA and FACS test results in Table 1 and other tables of the present invention are interpreted as N / A: no binding activity or poor binding activity, and no effective EC 50 Values; N / T not tested. *HAT medium or mIgG, #prefusion mouse antibody serum or rovalpituzumab-mIgG.

[0220] Example 2: Purification and functional characterization of mouse monoclonal antibodies against human DLL3

[0221] Hybridoma cells with hDLL3-His binding activity (as listed in Table 1) were cultured in serum-free medium. After 10 days, the culture supernatant was collected and purified using a Protein A column (Bioglone (Shanghai) Biotechnology Co., Ltd., Catalog No. AA0272) to obtain purified mouse monoclonal antibodies. Binding activity, nonspecific ADC-antibody activity, and internalization efficiency were tested.

[0222] 2.1 Binding activity of anti-human DLL3 mouse monoclonal antibodies to human and cynomolgus monkey DLL3 proteins

[0223] The binding activity of mouse monoclonal antibodies against human DLL3 to human DLL3 protein and cynomolgus monkey DLL3 protein was tested by enzyme-linked immunosorbent assay (ELISA). High-absorption 96-well ELISA plates were coated with 1 μg / mL human DLL3, his protein (Acro, DL3-H52H4) or cynomolgus monkey DLL3, his protein (Acro, DL3-C52H3) and blocked with 1% BSA-PBS blocking buffer at 37°C for 1 hour. A serial dilution of the antibody (starting at 40 nM and followed by 4-fold dilution) was prepared in 1% BSA-PBST (0.05% PBST). 100 μL of the antibody was added to each well of the blocked 96-well ELISA plate and incubated at 37°C. After 1 hour, washing three times with 0.05% PBST, 100 μL of HRP-labeled secondary antibody (Sigma, A0168) diluted in 1% BSA-PBS was added to the ELISA plate per well, incubated at 37°C for 1 hour, washed three times with PBST, and developed with TMB (BD, 555214). After termination with stop solution (Solarbio, C1058), the absorbance at 450 nm and 630 nm was measured using a microplate reader. The OD450-OD630 values ​​were fitted using a four-parameter model to calculate the EC value of each antibody. 50 value.

[0224] As shown in Table 2, at the molecular level, the binding activity of 177D10F11 anti-human DLL3 mouse monoclonal antibody to human and cynomolgus monkey DLL3 proteins (EC 50 ) was superior to or similar to the positive control antibody Rovalpituzumab-mIgG.

[0225] Table 2 EC values ​​of mouse monoclonal antibodies against human DLL3 binding to human and cynomolgus monkey DLL3 proteins 50 value

[0226] Note: Rovalpituzumab-mIgG EC in Table 2 and other tables of the present invention 50 is the average value of multiple experiments; EC 50 The unit of values ​​is nM.

[0227] 2.2 Binding activity of mouse monoclonal antibodies against human DLL3 to cell surface human and cynomolgus monkey DLL3

[0228] Flow cytometry (FACS) was used to detect the binding activity of a mouse monoclonal antibody against human DLL3 to human and cynomolgus macaque DLL3 antigens on the surfaces of CT26 cells overexpressing human DLL3 (CT26-hDLL3, Kangyuan Broad, KC-1129), SHP77 cells (ATCC, CRL-2195), and HEK293T cells overexpressing cynomolgus macaque DLL3 (HEK293-cynoDLL3, Kangyuan Broad, KC-0294). CT26-hDLL3 cells and CHOK1-cynoDLL3 cells were digested with standard trypsin (Gibco, 25200072). SHP77 cells were removed from the culture flask, counted by centrifugation, plated into a 96-well U-bottom plate, and centrifuged at 300 g for 5 minutes. The supernatant was discarded. Add 100 μL of antibody concentration gradient dilution prepared with FACS buffer, mix well, incubate at 4°C for 60 minutes, wash three times with FACS buffer, add 100 μL / well of AF647-anti-mIgG (H+L) (Invitrogen, A31571; 1:1000) secondary antibody diluted in FACS buffer, incubate at 4°C for 1 hour, wash three times with FACS buffer, resuspend the cells in 100 μL / well of FACS buffer, and detect the fluorescence signal on a flow cytometer (BECKMAN COULTER cytoFLEX). The binding activity was fitted using a four-parameter model to calculate the EC of each antibody. 50 value.

[0229] As shown in Table 3, the 177D10F11 anti-human DLL3 mouse monoclonal antibody exhibited good binding activity to cells expressing human DLL3 and cells expressing cynomolgus monkey DLL3.

[0230] Table 3 Binding activity of mouse monoclonal antibodies against human DLL3 to human and cynomolgus monkey DLL3 on cell surface

[0231] Note: The binding activity results of monoclonal antibodies to DLL3 from different sources in Table 3 and other tables of the present invention are N / A, which means that no effective EC was fitted. 50 value.

[0232] 2.3 Binding activity of anti-human DLL3 mouse monoclonal antibody to mouse DLL3

[0233] The binding activity of anti-human DLL3 mouse monoclonal antibody to mouse DLL3 protein was detected by enzyme-linked immunosorbent assay (ELISA).

[0234] A high-absorption 96-well microtiter plate was coated with 2 μg / mL mouse DLL3 protein (CUSABIO, CSB-MP006948MO1) at 4°C overnight. The next day, the plate was blocked with 1% BSA-PBS blocking buffer at 37°C for 1 hour. A gradient dilution of the antibody was prepared with 1% BSA-PBST and added to the blocked 96-well microtiter plate at 100 μL per well. The plate was incubated at 37°C for 1 hour and washed three times with 0.05% PBST. HRP-labeled secondary antibody (Sigma, A0168) diluted in 1% BSA-PBST was added to the plate at 100 μL per well. The plate was incubated at 37°C for 1 hour and washed three times with PBST. TMB color development (BD, 555214) and stop solution (Solarbio, C1058) were used for colorimetric analysis. The absorbance at 450 nm and 630 nm was measured using a microtiter plate reader. The OD450-OD630 values ​​were fitted using a four-parameter model to calculate the EC value of each antibody. 50 value.

[0235] As shown in Table 4, the anti-human DLL3 mouse monoclonal antibodies 135A9B10 and 177D10F11 had good binding activity to mouse DLL3.

[0236] Table 4 Binding activity of anti-human DLL3 mouse monoclonal antibodies to mouse DLL3 antigen

[0237] 2.4 ELISA assay for nonspecific binding of anti-human DLL3 mouse monoclonal antibodies to human DLL1 and DLL4 proteins

[0238] High-adsorption 96-well ELISA plates were coated with 1 μg / mL human DLL1 protein (Acro, DL1-H52H8) and human DLL4 protein (Acro, DL4-H5227), incubated at 37°C for 1 hour, washed three times with 0.05% PBST, blocked with 1% BSA-PBS blocking solution at 37°C for 1 hour, washed three times with 0.05% PBST, and then 100 μL of antibody concentration gradient dilutions prepared with 1% BSA-PBST (starting concentration 30 μg / mL, 4-fold dilution) were added to each well, incubated at 37°C for 1 hour, washed three times with 0.05% PBST. , 100 μL of HRP-labeled secondary antibody (mouse anti-DLL3 monoclonal antibody: Sigma, A0168; positive control anti-DLL1 and anti-DLL4 antibodies: Invitrogen, A16116; 1:10,000 dilution) diluted in 1% BSA-PBST was added to the ELISA plate per well, incubated at 37°C for 1 hour, washed three times with PBST, and developed with TMB (BD, 555214). After termination with stop solution (Solarbio, C1058), the absorbance at 450 nm was measured using a microplate reader, and the OD450 value was fitted using a four-parameter model.

[0239] As shown in Figures 1 and 2 , the anti-human DLL3 mouse monoclonal antibodies 177D10F11, 135A9B10, and 137G3D11 had no significant nonspecific binding activity to human DLL1 and human DLL4 proteins.

[0240] 2.5 Cytotoxicity Induced by αMFc-CL-DX8951 and Mouse Monoclonal Antibody Against Human DLL3

[0241] αMFc-CL-DX8951 (Moradec, AM-107-DX-50) is an anti-mouse IgG Fc-specific antibody conjugated to DX8951 via a cleavable linker. αMFc-CL-DX8951 recognizes the Fc terminus of the anti-human DLL3 murine antibody, leading to endocytosis and intracellular release of DX8951 in DLL3-expressing cells, resulting in cell killing. Antibody concentration gradient dilutions and secondary antibody αMFc-CL-DX8951 working solution (4-fold final concentration of 26.4 nM) were prepared in culture medium. CynoDLL3-HEK293 cells were obtained by digestion with trypsin (Gibco, 25200072), or SHP77 cells were directly aspirated from the culture flask and adjusted to a cell density of 1E5 / mL by centrifugation. 25 μL of antibody concentration gradient dilutions and 50 μL of cell suspension were added to each well of a white low-transparency 96-well plate. After incubation for 10 minutes, 25 μL of secondary antibody working solution was added to each well. The 96-well plate was placed in a 37°C, 5% CO2 incubator for 5 to 7 days. 50 μL of CTG was added to each well, and the fluorescence values ​​were read using a microplate reader. The fluorescence values ​​were fitted using a four-parameter model to calculate the EC value of each antibody. 50 value.

[0242] As shown in Table 5, the anti-human DLL3 antibody clone 177D10F11 exhibited cell killing activity that was similar to or better than that of the control antibody Rovalpituzumab-mIgG.

[0243] Table 5 EC of cytotoxicity induced by αMFc-CL-DX8951 and mouse monoclonal antibody against human DLL3 50

[0244] 2.6 Endocytosis function detection of mouse monoclonal antibody against human DLL3

[0245] 5 μg / mL antibody dilution was prepared in pre-cooled FACS Buffer, hDLL3-CT26 cells were obtained by trypsin digestion, and counted by centrifugation. 1E6 cells / tube were transferred to 1.5 mL centrifuge tubes and centrifuged. The prepared 5 μg / mL antibody dilution was added to each tube and incubated in the dark at 4°C for 1 hour. After washing 3 times with pre-cooled FACS Buffer, the cells were resuspended in 1 mL / tube of pre-cooled FACS Buffer. The EP tubes were placed in the dark at 4°C and 100 μL of cell suspension was taken from the EP tube at 0 min, 60 min, 90 min, 105 min and 115 min and added to a 96-well U-bottom plate. The cells were incubated at 37°C. After 120 minutes of incubation, the 96-well plate was removed and incubated on ice for 5 minutes. 100 μL of cell suspension was taken from the EP tube again and added to the 96-well plate. After washing 3 times with pre-cooled FACS Buffer, 100 μL of AF647 donkey was added to each well. Anti-mouse IgG (H+L) secondary antibody (Invitrogen, A31571) was used and incubated at 4°C in the dark for 40 min. Fluorescence values ​​were read by flow cytometry, and the endocytic rate was calculated using the formula (G.MFI[0 mins]-G.MFI[time]) / G.MFI[0 mins]×100%.

[0246] As shown in Table 6, the endocytic capacity of the 177D10F11 anti-human DLL3 mouse monoclonal antibody was comparable to that of the positive control antibody Rovalpituzumab-mIgG.

[0247] Table 6 Internalization rate of mouse monoclonal antibodies against human DLL3 in hDLL3-CT26 cells for 5-120 minutes

[0248] 2.7 Affinity testing of mouse monoclonal antibodies against human DLL3

[0249] A 5 μg / mL antibody working solution and a DLL3-his antigen serial dilution solution (starting concentration 100 nM, 2-fold dilution) were prepared in buffer (0.05% PBST). The binding assay was performed using Anti-Mouse IgG Fc Capture (AMG) Biosenseors (Fortebio, 18-5088), with a baseline of 1 minute, loading of 3 minutes, baseline 2 of 2 minutes, association of 3 minutes, and dissociation of 10 minutes. Data were analyzed using ForteBio Data ANAlysis 11.0 software.

[0250] As shown in Table 7, the anti-human DLL3 antibody clones 177D10F11, 137G3D11, and 135A9B10 had affinities for human DLL3 protein comparable to or better than the control antibody Rovalpituzumab-mIgG.

[0251] Table 7 Affinity of anti-DLL3 mouse monoclonal antibodies to human DLL3 protein

[0252] Example 3: Anti-DLL3 Antibody Sequencing and Synthesis of Chimeric Antibodies

[0253] 3.1 Anti-DLL3 Antibody Sequencing and Synthesis of Chimeric Antibodies

[0254] Hybridoma clones that performed well in the aforementioned activity assays were sequenced, and the sequences are shown in Table 8. The sequenced light and heavy chain variable regions were then constructed onto human constant regions (IgG1 / κ, Table 9) for in vitro functional characterization and in vivo efficacy studies. Sequencing confirmed that the constructed hIgG1 chimeric antibodies were consistent with the sequences listed in Tables 8 and 9.

[0255] The corresponding nucleic acid encoding the antibody was transfected into Expi293 cells, and the antibody was expressed in Expi293 cells and purified using a Protein A column. The specific method is as follows:

[0256] Expi293 cells expressing antibodies: 1.5 × 10 6 Cells were cultured at 37°C in a shaker with 8% CO2 at 120 rpm. The next day, the cell density and viability were measured. The density should be around 3×10 6 Cells / mL, with a viability greater than 95%. Dilute the plasmid containing the encoding nucleic acid in OPM-293CD05 Medium (OPM, Catalog No. 81075-001) to 1 μg / mL. The volume of medium used to dilute the plasmid should be 1 / 20 of the transfection volume, with a light chain to heavy chain ratio of 1:1.5. Invert to mix thoroughly. Dilute the PEI reagent in OPM-293CD05 Medium to 1 / 20 of the transfection volume, and incubate at room temperature for 5 minutes. Add the diluted PEI reagent to the diluted plasmid, mix thoroughly, and incubate at room temperature for 15 minutes. Incubate the flask at 37°C, 8% CO2, and 120 rpm in a shaker for 24 hours. Add 10% OPM-293 ProFeed (OPM, Catalog No. F081918), continue incubation for 5-7 days, and collect the supernatant.

[0257] Protein A column purification of antibodies: Place the gasket at the bottom of the gravity column and press it tightly. Filler suspension volume = target filler volume / filler suspension ratio. Vortex the filler thoroughly and add it to the bottom of the gravity chromatography column. Add PBS to the gravity chromatography column until the outlet pH is balanced to the target pH. Slowly add a certain volume of sample to the gravity chromatography column, add at least 10CV of wash buffer, add 5CV of elution buffer (10-50mM NaAc, pH3.0-pH3.5), incubate for 3-5 minutes, and collect the eluate. Adjust the pH to 7.2 with neutralization buffer (1M Tris). Determine the protein concentration using Nanodrop. Use a Millipore ultrafiltration centrifuge tube (50kDa) to exchange the liquid into PBS.

[0258] Table 8 CDR sequences of anti-DLL3 antibodies

[0259] The amino acid sequence of the heavy chain variable region of the murine monoclonal antibody 177D10F11 is SEQ ID NO: 7:

[0260] The amino acid sequence of the light chain variable region of the murine monoclonal antibody 177D10F11 is SEQ ID NO: 8:

[0261] The amino acid sequence of the heavy chain variable region of the murine monoclonal antibody 135A9B10 is SEQ ID NO: 21:

[0262] The amino acid sequence of the light chain variable region of the murine monoclonal antibody 135A9B10 is SEQ ID NO: 22:

[0263] The amino acid sequence of the heavy chain variable region of the murine monoclonal antibody 137G3D11 is SEQ ID NO: 35:

[0264] The amino acid sequence of the light chain variable region of the murine monoclonal antibody 137G3D11 is SEQ ID NO: 36:

[0265] Table 9 Chimeric and humanized antibody constant region sequences

[0266] Example 4: Functional characterization of anti-DLL3 chimeric antibodies

[0267] 4.1 Cytotoxicity Induced by αHFc-CL-DX8951 and Anti-DLL3 Chimeric Monoclonal Antibody

[0268] αHFc-CL-DX8951 (Moradec, AH-107-DX-50) is an anti-human IgG Fc-specific antibody conjugated to DX8951 via a cleavable linker. αHFc-CL-DX8951 recognizes the Fc terminus of anti-DLL3 chimeric or humanized antibodies, leading to endocytosis and intracellular release of DX8951 in DLL3-expressing cells, resulting in cell killing. Antibody concentration gradient dilutions (4-fold starting concentration of 20 nM, 4-fold dilution) and secondary antibody αHFc-CL-DX8951 working solution (4-fold final concentration of 26.4 nM) were prepared in culture medium. SHP77 cells were aspirated from the culture flask and the cell density was adjusted to 1E5 / mL by centrifugation. 25 μL of the antibody concentration gradient dilutions and 50 μL of the cell suspension were added to each well of a white low-transparency 96-well plate. After incubation for 10 minutes, 25 μL of the secondary antibody working solution were added to each well. The 96-well plate was placed in a cell culture incubator and cultured at 37°C, 5% CO for 6 days. 50 μL of CTG was added to each well, and the fluorescence values ​​were read using a microplate reader. The fluorescence values ​​were fitted using a four-parameter model to calculate the EC value of each antibody. 50 value.

[0269] As shown in Table 10, the cell killing activity of the ch177D10F11 chimeric antibody was comparable to that of the positive control antibody Rovalpituzumab.

[0270] Table 10 EC values ​​of cytotoxicity induced by αHFc-CL-DX8951 and anti-DLL3 chimeric monoclonal antibody 50

[0271] 4.2 Humanization of anti-DLL3 antibodies and functional characterization of humanized antibodies

[0272] Using Kabat numbering to identify CDRs, the human germline gene with the highest homology to the mouse sequence was selected as the acceptor framework, and the mouse CDRs were transplanted into the human framework. Based on the importance of amino acids, backmutations were performed, remutating key amino acids in the transplanted framework region to their corresponding mouse counterparts. Several variants were designed for each heavy and light chain.

[0273] 4.2.1 Humanization of anti-DLL3 antibody 177D10F11

[0274] Table 11 Humanized sequences designed for anti-DLL3 antibody 177D10F11

[0275] 4.2.2 Humanization of anti-DLL3 antibody 135A9B10

[0276] Table 12 Humanized heavy and light chain sequences designed for anti-DLL3 antibody 135A9B10

[0277] 4.2.3 Humanization of anti-DLL3 antibody 137G3D11

[0278] Table 13 Humanized sequences designed for anti-DLL3 antibody 137G3D11

[0279] Table 14: Sequence numbers corresponding to humanized anti-DLL3 antibodies

[0280] 4.3 Expression and purification of humanized anti-DLL3 antibodies

[0281] The light and heavy chain variable regions of the humanized antibody were constructed onto the human constant region (IgG1 / κ, Table 9), and gene synthesis was performed. Sequencing confirmed that the sequence was consistent with the design. Expression was performed in Expi293 cells using the method described in 3.1 and purification was performed using a Protein A column.

[0282] Example 5: Binding activity of anti-DLL3 humanized antibodies

[0283] 5.1 Detection of Binding Activity of Humanized Anti-DLL3 Antibodies to Human DLL3

[0284] Flow cytometry was used to determine the binding activity of a humanized monoclonal antibody against human DLL3 on the surface of SHP77 cells (ATCC, CRL-2195) and HEK293 cells overexpressing cynomolgus macaque DLL3 (Kangyuan Broad, KC-0294). HEK293 cells overexpressing cynomolgus macaque DLL3 were harvested by trypsinization. SHP77 cells were removed from the culture flask and pipetted to single cells. The cells were counted, adjusted to a cell concentration, and plated into a 96-well U-bottom plate. The cells were centrifuged at 300 g for 5 minutes, the supernatant discarded, and 100 μL of serial dilutions of the antibody prepared in FACS buffer were added, mixed, and incubated at 4°C for 60 minutes. After washing three times with FACS buffer, AF647-anti-hIgG (H+L) (1:1000, Invitrogen, A21445) was added at 100 μL / well and incubated at 4°C for 1 hour. After washing three times with FACS buffer, the cells were resuspended in 100 μL / well FACS buffer and the fluorescence signal was detected on a flow cytometer (BECKMAN COULTER cytoFLEX). The binding activity was fitted using a four-parameter model to calculate the EC value of each antibody. 50 value.

[0285] As shown in Table 15, the tested anti-DLL3 humanized antibodies had good binding activity to both human and cynomolgus monkey DLL3 proteins on the cell surface.

[0286] Table 15 Binding activity of humanized monoclonal antibodies against DLL3 to human DLL3 protein and human DLL3 protein on the surface of SHP77 cells

[0287] 5.2 Affinity testing of humanized anti-DLL3 antibodies

[0288] A 5 μg / mL antibody working solution and a DLL3-his antigen gradient dilution solution (starting concentration 100 nM, 2-fold dilution) were prepared in buffer (0.05% TPBS). The binding assay was run using Anti-Human IgG Fc Capture (AHG) Biosenseors (Fortebio, 18-5068), with a baseline of 1 minute, loading of 3 minutes, baseline2 of 2 minutes, association of 3 minutes, and dissociation of 10 minutes. Data were analyzed using ForteBio Data Analysis 11.0 software.

[0289] As shown in Table 16, all tested antibodies have good affinity for human DLL3 protein.

[0290] Table 16 Affinity of anti-DLL3 humanized antibodies to human DLL3 protein

[0291] Example 6: Anti-DLL3 humanized antibody ADC conjugation and in vitro killing activity detection

[0292] 6.1 Anti-DLL3 Humanized Antibody-MMAE Conjugation

[0293] A certain amount of antibody and PBS buffer were added to adjust the concentration of the antibody in the reaction mixture to approximately 1 mg / mL. A certain amount of EDTA solution was added to adjust the EDTA concentration of the mixture to approximately 2 mM. 1 M Tris saline was added to adjust the pH of the reaction system to between 6.6 and 7.5. 2-6 equivalents of TCEP were added for reduction, and the mixture was gently shaken on a mixer at 37°C for 1-3 hours. The mixer temperature was then adjusted to approximately 4°C, the reaction solution was cooled, and 5-10 equivalents of DMSO-dissolved Vc-MMAE (MCE, HY-15575) were added. The mixture was reacted at 4°C for 1-2 hours. Finally, the reaction solution was added to a 30Ka ultrafiltration tube, and the solution was replaced 6-8 times with 10 mM, pH 6.0 histidine hydrochloric acid solution. The solution was concentrated to an appropriate volume and added to a well-equilibrated desalting column. The purified ADC product was centrifuged and the DAR value was detected. The DAR value test results of the ADC sample are shown in Table 17. The structure of the anti-human DLL3 antibody and MMAE conjugate is shown below.

[0294] Anti-DLL3 humanized antibody-MMAE conjugate structure

[0295] 6.2 Anti-DLL3 Humanized Antibody-Dxd Conjugate

[0296] Add the antibody to PBS buffer to a reaction concentration of 1.0 mg / mL. Add 500 mM EDTA (Shanghai Test, 10009617) to a final EDTA concentration of 2 mM. Add TCEP solution (Thermo, 20490) to the reaction solution, mix thoroughly (molar ratio of TCEP:mAb = 6:1), and react at 37°C, 600 rpm for 2 hours. After the reaction is complete, cool the reaction solution to 4°C and add Deruxtecan solution (MCE, HY-1363E) dissolved in DMSO to the reaction solution. Mix thoroughly (molar ratio of drug:mAb = 15:1), and react at 4°C, 600 rpm for 1 hour. After the reaction, the reaction solution was added to a 30K ultrafiltration tube, and the solution was replaced with 10 mM histidine hydrochloric acid solution, pH 6.0, for 6-8 DV. After concentration to an appropriate volume, the solution was added to a equilibrated desalting column and centrifuged to obtain the purified ADC product. The final concentration was determined by Nanodrop, the purity was determined by SEC-HPLC, and the DAR value was determined by RP-HPLC / HIC-HPLC. The DAR value test results of the ADC sample are shown in Table 17. The structure of the anti-human DLL3 antibody and Dxd conjugate is shown below.

[0297] Anti-human DLL3 antibody-Dxd conjugate structure

[0298] Table 17 Characterization analysis results of anti-human DLL3 antibody and Dxd or MMAE conjugates

[0299] 6.3 Cytotoxicity of anti-DLL3 antibody-ADC against HEK293-cynoDLL3 cells and NCI-H524 cells

[0300] Adjust the cell concentration and inoculate 50 μL / well in a white opaque plate, and culture overnight in a 37°C, 5% CO2 incubator. Add anti-DLL3 antibody-ADC, positive control antibody-ADC, and Isotype hIgG1-ADC diluted in culture medium at 50 μL / well and culture in a 37°C, 5% CO2 incubator for 4-6 days. Add luciferase substrate solution, mix, and react in the dark for 5 minutes at room temperature. Read the relative light unit (RLU) value on the cell culture plate using a microplate reader. GraphpadPrism 8.0 software was used to analyze the experimental data, with the logarithm of the antibody concentration as the x-axis and the corresponding RLU value as the y-axis. A four-parameter regression model was selected to fit the antibody dose-effect curve and calculate the EC 50 value.

[0301] The experimental results in Figures 3, 4 and Table 18 indicate that hz177D10F11-H1L1-ADC exhibits better cell killing activity than Isotype hIgG1-ADC, and the killing activity of hz177D10F11-H1L1-ADC is comparable to that of the positive control Rovalpituzumab-ADC.

[0302] Table 18 Cytotoxicity of anti-human DLL3 humanized antibody ADC against HEK293-cynoDLL3 and NCI-H524 cells

[0303] Example 7: In vivo killing ability detection of anti-human DLL3 antibody ADC

[0304] This example aims to investigate the ability of anti-human DLL3 antibody ADC to inhibit tumor growth in the mouse NCI-H524 model.

[0305] 7.1 Preparation of anti-human DLL3 antibody and Dxd conjugates

[0306] The steps are shown in section 6.2, "Anti-human DLL3 humanized antibody-Dxd conjugation".

[0307] 7.2 Anti-human DLL3 antibody ADC inhibits the growth of NCI-H524 (human non-small cell lung cancer cells) in an immunodeficient mouse (Balb / c Nude) model

[0308] The NCI-H524 human non-small cell lung cancer mouse model was established using human immunodeficient mice (Balb / c Nude, BALB / cNj-Foxn1nu / Gpt, Jiangsu Jicui Pharmaceutical Biotechnology Co., Ltd., strain code: D000521) and the anti-tumor efficacy of different anti-human DLL3 antibody ADC molecules in this mouse tumor model was tested. NCI-H524 cells were diluted with serum-free medium (RPMI 1640), and then the corresponding volume of Matrigel (Cat. No.: 354234, BD) was added and mixed with the cell solution (RPMI 1640 medium: Matrigel = 7:3). After that, 5×10 6 cells / cells were inoculated subcutaneously in the right flank of Balb / cNude mice. When the average tumor volume reached about 150 mm 3 At the same time, 5 mice were divided into groups and injected (iv) with vehicle control (histidine hydrochloride buffer), hIgG1-Dxd DAR 6.0-1 mg / kg, Rovalpituzumab-Dxd DAR 7.6-1 mg / kg and hz177D10F11-H1L1-Dxd DAR 7.5-1 mg / kg at a dosage volume of 10 mL / kg. After administration, the mice were fed normally, and their survival was observed. The body weight and tumor volume of the mice were recorded every Tuesday and Friday for 3 weeks. Figure 5 is a curve of the inhibition of NCI-H524 tumor cell growth by anti-human DLL3 antibody ADC, and Figure 6 is a curve of the weight change rate of mice in the NCI-H524 tumor model inhibited by anti-human DLL3 antibody ADC. As shown in Figures 5 and 6, starting from the 8th day after administration, the tumor volume of the vehicle control group was 474.9±100.3 mm 3 The tumor volumes of the Rovalpituzumab-DxdDAR 7.6-1 mg / kg group and the hz177D10F11-H1L1-Dxd DAR 7.5-1 mg / kg group were 196.1±60.9 mm 3 、115.5±26.6mm 3 , TGI TV (tumor volume inhibition rate) were 58.7% and 75.7% respectively. Then on days 11, 14, 17 and 21, the TGI of the Rovalpituzumab-Dxd DAR 7.6-1 mg / kg group was significantly higher than that of the control group. TV The TGI of hz177D10F11-H1L1-Dxd DAR7.5-1mg / kg group were 69.8%, 67.7%, 64.4% and 58.2% respectively. TVThe results were 89.4%, 89.4%, 89.4%, and 86.4%, respectively. During the observation period, tumor-bearing mice tolerated the test product well, with no weight loss. At a single dose of 1 mg / kg, hz177D10F11-H1L1-Dxd DAR 7.6 significantly inhibited tumor growth.

[0309] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

[0310] Sequence information

[0311] CDR, heavy chain variable region, light chain variable region sequences:

[0312] Anti-DLL3 antibody humanized heavy chain and light chain combination

[0313] Rovalpituzumab and Rovalpituzumab-mIgG full-length sequences

Claims

1. An antibody or antigen-binding fragment thereof that binds to DLL3, comprising heavy chain complementarity determining regions HCDR1, HCDR2, and HCDR3, and / or light chain complementarity determining regions LCDR1, LCDR2, and LCDR3, wherein: 1) HCDR1 comprises the sequence shown in SEQ ID NO:1, or a sequence having one or more amino acid substitutions, deletions, or insertions, or any combination thereof, relative to SEQ ID NO:1, or consists of SEQ ID NO:1; HCDR2 comprises the sequence shown in SEQ ID NO:2, or a sequence having one or more amino acid substitutions, deletions, or insertions, or any combination thereof, relative to SEQ ID NO:2, or consists of SEQ ID NO:2; HCDR3 comprises the sequence shown in SEQ ID NO:3, or a sequence having one or more amino acid substitutions, deletions, or insertions, or any combination thereof, relative to SEQ ID NO:3, or consists of SEQ ID NO:3; LCDR1 comprises the sequence shown in SEQ ID NO:4, or a sequence having one or more amino acid substitutions, deletions, or insertions, or any combination thereof, relative to SEQ ID NO:4, or consists of SEQ ID NO:4; LCDR2 comprises the sequence shown in SEQ ID NO:5, or a sequence having one or more amino acid substitutions, deletions, or insertions, or any combination thereof, relative to SEQ ID NO:5, or consists of SEQ ID NO:5; LCDR3 comprises the sequence shown in SEQ ID NO:6, or a sequence having one or more amino acid substitutions, deletions, or insertions, or any combination thereof, relative to SEQ ID NO:6, or consists of SEQ ID NO:6; 2) HCDR1 comprises the sequence shown in SEQ ID NO: 15, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 15, or consists of SEQ ID NO: 15; HCDR2 comprises the sequence shown in SEQ ID NO: 16, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 16, or consists of SEQ ID NO: 16; HCDR3 comprises the sequence shown in SEQ ID NO: 17, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 17, or consists of SEQ ID NO: 17; LCDR1 comprises the sequence shown in SEQ ID NO: 18, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 18, or consists of SEQ ID NO: 18; LCDR2 comprises the sequence shown in SEQ ID NO: 19, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 19, or consists of SEQ ID NO: 19; LCDR3 comprises the sequence shown in SEQ ID NO: 20, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 20, or consists of SEQ ID NO: 20; or 3) The HCDR1 comprises the sequence shown in SEQ ID NO: 29, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 29, or consists of SEQ ID NO: 29; the HCDR2 comprises the sequence shown in SEQ ID NO: 30, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 30, or consists of SEQ ID NO: 30; the HCDR3 comprises the sequence shown in SEQ ID NO: 31, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 31, or consists of SEQ ID NO: 31; the LCDR1 comprises the sequence shown in SEQ ID NO: 32, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 32, or consists of SEQ ID NO: 32; the LCDR2 comprises the sequence shown in SEQ ID NO: 33, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 33, or consists of SEQ ID NO: 33; the LCDR3 comprises the sequence shown in SEQ ID NO: 34, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 34, or consists of SEQ ID NO:

34.

2. The antibody or antigen-binding fragment thereof that binds to DLL3 according to claim 1, which comprises a heavy chain variable region and / or a light chain variable region, wherein: 1) The heavy chain variable region comprises the amino acid sequence shown in SEQ ID NO: 7, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 7, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 7, or consists of SEQ ID NO: 7; and / or the light chain variable region comprises the amino acid sequence shown in SEQ ID NO: 8, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 8, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 8, or consists of SEQ ID NO: 8; 2) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 9, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 9, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 9, or consists of SEQ ID NO: 9; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 12, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 12, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 12, or consists of SEQ ID NO: 12; 3) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 9, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 9, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 9, or consists of SEQ ID NO: 9; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 13, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 13, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 13, or consists of SEQ ID NO: 13; 4) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 9, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 9, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 9, or consists of SEQ ID NO: 9; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 14, or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 14, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 14, or consists of SEQ ID NO: 14; 5) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 10, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 10, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 10, or consists of the amino acid sequence of SEQ ID NO: 10; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 12, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 12, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 12, or consists of the amino acid sequence of SEQ ID NO: 12; 6) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 10, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 10, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 10, or consists of the amino acid sequence of SEQ ID NO: 10; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 13, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 13, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 13, or consists of the amino acid sequence of SEQ ID NO: 13; 7) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 10, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 10, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 10, or consists of the amino acid sequence of SEQ ID NO: 10; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 14, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 14, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 14, or consists of the amino acid sequence of SEQ ID NO: 14; 8) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO:11, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO:11, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO:11, or consists of the amino acid sequence of SEQ ID NO:11; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO:12, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO:12, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO:12, or consists of the amino acid sequence of SEQ ID NO:12; 9) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO:11, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO:11, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO:11, or consists of the amino acid sequence of SEQ ID NO:11; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO:13, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO:13, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO:13, or consists of the amino acid sequence of SEQ ID NO:13; 10) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO:11, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO:11, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO:11, or consists of the amino acid sequence of SEQ ID NO:11; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO:14, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO:14, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO:14, or consists of the amino acid sequence of SEQ ID NO:14; 11) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 21, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 21, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 21, or consists of the amino acid sequence of SEQ ID NO: 21; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 22, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 22, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 22, or consists of the amino acid sequence of SEQ ID NO: 22; 12) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 23, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 23, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 23, or consists of the amino acid sequence of SEQ ID NO: 23; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 28, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 28, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 28, or consists of the amino acid sequence of SEQ ID NO: 28; 13) The heavy chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 35, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 35, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 35, or consists of the amino acid sequence of SEQ ID NO: 35; and / or the light chain variable region comprises an amino acid sequence as shown in SEQ ID NO: 36, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 36, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 36, or consists of the amino acid sequence of SEQ ID NO: 36; 14) The heavy chain variable region comprises the amino acid sequence shown in SEQ ID NO: 40, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 40, or an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 40, or consists of SEQ ID NO: 40; and / or the light chain variable region comprises the amino acid sequence shown in SEQ ID NO: 43, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 43, or an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 43, or consists of SEQ ID NO: 43; 15) The heavy chain variable region comprises the amino acid sequence shown in SEQ ID NO: 40, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 40, or an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 40, or consists of SEQ ID NO: 40; and / or the light chain variable region comprises the amino acid sequence shown in SEQ ID NO: 44, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 44, or an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 44, or consists of SEQ ID NO: 44; or 16) The heavy chain variable region comprises the amino acid sequence shown in SEQ ID NO: 41, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 41, or an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 41, or consists of SEQ ID NO: 41; and / or the light chain variable region comprises the amino acid sequence shown in SEQ ID NO: 43, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 43, or an amino acid sequence having at least 90% identity to the amino acid sequence of SEQ ID NO: 43, or consists of SEQ ID NO:

43.

3. The antibody or antigen-binding fragment thereof that binds to DLL3 according to claim 1 or 2, wherein, The antibody is in any form such as a monoclonal antibody, single-chain antibody, bifunctional antibody, single-domain antibody, nanobody, fully or partially humanized antibody, or chimeric antibody; and / or The antigen-binding fragment is an antigen-binding fragment of an antibody or a half-antibody, such as a Fab, Fab', Fab'-SH, (Fab')2, Fv, scFv, BsFv, dsFv or (dsFv)2 fragment.

4. The antibody or antigen-binding fragment thereof that binds to DLL3 according to any one of claims 1-3, wherein, The antibody or its antigen-binding fragment further comprises a human or murine constant region, preferably comprising a human or murine heavy chain constant region and / or light chain constant region; More preferably, the antibody or its antigen-binding fragment comprises a heavy chain constant region of IgG, IgA, IgM, IgD or IgE and / or a kappa or lambda light chain constant region.

5. An antibody or antigen-binding fragment thereof that binds to DLL3 according to any one of claims 1-4, wherein, The antibody is a monoclonal antibody, preferably a murine, chimeric or humanized monoclonal antibody; preferably, the heavy chain constant region of the monoclonal antibody is an IgG1, IgG2, IgG3, IgG4 subtype; More preferably, the heavy chain constant region comprises or consists of the sequence shown in SEQ ID NO: 45; and / or the light chain constant region comprises or consists of the sequence shown in SEQ ID NO:

46.

6. The antibody or its antigen-binding fragment that binds to DLL3 according to any one of claims 1-5, which comprises a heavy chain and / or a light chain, wherein: 1) The heavy chain comprises the amino acid sequence shown in SEQ ID NO: 47 or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 47, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 47, or consists of SEQ ID NO: 47, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 48 or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 48, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 48, or consists of SEQ ID NO: 48; 2) The heavy chain comprises the amino acid sequence shown in SEQ ID NO: 47 or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 47, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 47, or consists of SEQ ID NO: 47, and the light chain comprises the amino acid sequence shown in SEQ ID NO: 49 or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 49, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 49, or consists of SEQ ID NO: 49; 3) The heavy chain comprises an amino acid sequence as shown in SEQ ID NO: 47, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 47, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 47, or consists of the amino acid sequence of SEQ ID NO:

47. The light chain comprises an amino acid sequence as shown in SEQ ID NO: 50, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 50, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 50, or consists of the amino acid sequence of SEQ ID NO: 50; 4) The heavy chain comprises an amino acid sequence as shown in SEQ ID NO: 51, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 51, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 51, or consists of the amino acid sequence of SEQ ID NO:

51. The light chain comprises an amino acid sequence as shown in SEQ ID NO: 48, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 48, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 48, or consists of the amino acid sequence of SEQ ID NO: 48; 5) The heavy chain comprises an amino acid sequence as shown in SEQ ID NO: 51, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 51, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 51, or consists of the amino acid sequence of SEQ ID NO:

51. The light chain comprises an amino acid sequence as shown in SEQ ID NO: 49, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 49, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 49, or consists of the amino acid sequence of SEQ ID NO: 49; 6) The heavy chain comprises an amino acid sequence as shown in SEQ ID NO: 51, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 51, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 51, or consists of SEQ ID NO: 51, and the light chain comprises an amino acid sequence as shown in SEQ ID NO: 50, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 50, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 50, or consists of SEQ ID NO: 50; 7) The heavy chain comprises an amino acid sequence as shown in SEQ ID NO: 52, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 52, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 52, or consists of SEQ ID NO: 52, and the light chain comprises an amino acid sequence as shown in SEQ ID NO: 48, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 48, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 48, or consists of SEQ ID NO: 48; 8) The heavy chain comprises an amino acid sequence as shown in SEQ ID NO: 52, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 52, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 52, or consists of SEQ ID NO: 52, and the light chain comprises an amino acid sequence as shown in SEQ ID NO: 49, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 49, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 49, or consists of SEQ ID NO: 49; 9) The heavy chain comprises an amino acid sequence as shown in SEQ ID NO: 52, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 52, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 52, or consists of SEQ ID NO: 52, and the light chain comprises an amino acid sequence as shown in SEQ ID NO: 50, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 50, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 50, or consists of SEQ ID NO: 50; 10) The heavy chain comprises an amino acid sequence as shown in SEQ ID NO: 53, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 53, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 53, or consists of SEQ ID NO: 53, and the light chain comprises an amino acid sequence as shown in SEQ ID NO: 54, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 54, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 54, or consists of SEQ ID NO: 54; 11) The heavy chain comprises an amino acid sequence as shown in SEQ ID NO: 55, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 55, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 55, or consists of SEQ ID NO: 55, and the light chain comprises an amino acid sequence as shown in SEQ ID NO: 56, or a sequence having one or more amino acid substitutions, deletions or insertions, or any combination thereof, relative to SEQ ID NO: 56, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 56, or consists of SEQ ID NO: 56; 12) The heavy chain comprises an amino acid sequence as shown in SEQ ID NO: 57 or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 57, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 57, or consists of the amino acid sequence of SEQ ID NO:

57. The light chain comprises an amino acid sequence as shown in SEQ ID NO: 58 or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 58, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 58, or consists of the amino acid sequence of SEQ ID NO: 58; or 13) The heavy chain comprises an amino acid sequence as shown in SEQ ID NO: 55 or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 55, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 55, or consists of the amino acid sequence of SEQ ID NO:

55. The light chain comprises an amino acid sequence as shown in SEQ ID NO: 58 or a sequence having one or more amino acid substitutions, deletions or insertions or any combination thereof relative to SEQ ID NO: 58, or an amino acid sequence having at least 90% identity with the amino acid sequence of SEQ ID NO: 58, or consists of the amino acid sequence of SEQ ID NO:

58.

7. A nucleic acid molecule encoding the antibody or an antigen-binding fragment thereof according to any one of claims 1-6, or encoding a heavy chain CDR, a light chain CDR, a heavy chain variable region, a light chain variable region, a heavy chain or a light chain comprised in the antibody or an antigen-binding fragment thereof.

8. A vector comprising the nucleic acid molecule according to claim 7.

9. A host cell comprising the nucleic acid molecule according to claim 7 and / or the vector according to claim 8, or the host cell is transformed or transfected with the nucleic acid molecule according to claim 7 and / or the vector according to claim 8.

10. The host cell according to claim 9, wherein the host cell is prokaryotic or eukaryotic. Preferably, the host cell is selected from yeast cells, CHO cells, 293 cells, plant cells or other cells suitable for preparing an antibody or an antigen-binding fragment thereof.

11. A method for preparing an antibody or an antigen-binding fragment thereof that binds to DLL3, the method comprising culturing a host cell comprising a nucleic acid molecule encoding the antibody or an antigen-binding fragment thereof according to any one of claims 1-6 under conditions suitable for expressing the antibody. Optionally, the method further comprises recovering the antibody or an antigen-binding fragment thereof from the host cell.

12. A conjugate comprising the antibody or an antigen-binding fragment thereof according to any one of claims 1-6 and a conjugate moiety, the conjugate moiety being another molecule; preferably, the conjugate moiety is a radioisotope, a fluorescent substance, a luminescent substance, a colored substance or an enzyme.

13. A pharmaceutical composition comprising the antibody or antigen-binding fragment thereof according to any one of claims 1-6, the nucleic acid molecule according to claim 7, the vector according to claim 8, the host cell according to claim 9 or 10, or the conjugate according to claim 12, and a pharmaceutically acceptable carrier.

14. The pharmaceutical composition according to claim 13, further comprising a second therapeutic agent and / or optionally pharmaceutical excipients, wherein the second therapeutic agent is selected from cytokines, antibodies, chemotherapeutic agents, and small molecule drugs.

15. An antibody-drug conjugate comprising the antibody or antigen-binding fragment thereof according to any one of claims 1-6, and further comprising a cytotoxic drug and a linker.

16. The antibody-drug conjugate according to claim 15, wherein the cytotoxic drug is selected from DX8951, MMAE, or Dxd, and the linker is a cleavable linker.

17. Use of the antibody or antigen-binding fragment thereof according to any one of claims 1-6, the nucleic acid molecule according to claim 7, the vector according to claim 8, the host cell according to claim 9 or 10, the conjugate according to claim 12, the pharmaceutical composition according to claim 13 or 14, or the antibody-drug conjugate according to claim 15 or 16 in the preparation of a drug for treating a disease suffered by a subject.

18. The use according to claim 17, wherein the disease is a DLL3-positive autoimmune disease or a DLL3-positive cancer.

19. The use according to claim 17 or 18, wherein the disease is a neuroendocrine tumor, lung cancer, prostate cancer, melanoma, or gastric cancer.

20. The use according to claim 19, wherein the lung cancer is small cell lung cancer, and the neuroendocrine tumor is castration-resistant neuroendocrine prostate cancer, large cell neuroendocrine carcinoma, or gastroenteropancreatic neuroendocrine tumor.

21. The antibody or antigen-binding fragment thereof according to any one of claims 1-6, the nucleic acid molecule according to claim 7, the vector according to claim 8, the host cell according to claim 9 or 10, the conjugate according to claim 12, the pharmaceutical composition according to claim 13 or 14, or the antibody-drug conjugate according to claim 15 or 16 for use as a drug or for treatment.

22. A method for preventing and / or treating a disease in a subject, the method comprising administering to a subject in need an effective amount of the antibody or antigen-binding fragment thereof according to any one of claims 1-6, the nucleic acid molecule according to claim 7, the vector according to claim 8, the host cell according to claim 9 or 10, the conjugate according to claim 12, the pharmaceutical composition according to claim 13 or 14, or the antibody-drug conjugate according to claim 15 or 16, wherein the disease includes tumors or autoimmune diseases; Preferably, the subject is a mammal; More preferably, the subject is a human.

23. A kit comprising the antibody or antigen-binding fragment thereof according to any one of claims 1-6 or the conjugate according to claim 12.

24. A method for detecting the presence or level of DLL3 in a sample, comprising the step of contacting the antibody or antigen-binding fragment thereof according to any one of claims 1-6 or the conjugate according to claim 12 with the sample and detecting whether the antibody or antigen-binding fragment thereof or the conjugate forms a complex with DLL3.

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