Bispecific Antibody Or Antigen-Binding Fragment Thereof, And Preparation Method Therefor

Abstract

Provided are a protein complex having a high heterodimer formation rate, a method of preparing the same, a pharmaceutical composition for preventing or treating cancer including the protein complex, and a method or preventing or treating cancer using the same. According to the same, bispecific antibodies or antigen-binding fragments with increased stability, receptors and receptor-binding agonists, antagonists, ligands, cytokines or receptor decoy biconjugates may be easily prepared and used in various fields such as disease prevention or treatment, and disease diagnosis.

Claims

1. A protein complex comprising a first polypeptide including a first CH3 antibody constant region and a second polypeptide including a second CH3 antibody constant region, wherein the first polypeptide and the second polypeptide form a heterodimer; the first CH3 antibody constant region comprises tryptophan (W) at position 366, and the second CH3 antibody constant region comprises serine (S) at position 366, alanine (A) at position 368, and valine (V) at position 407; and at least one of the first CH3 antibody constant region and the second CH3 antibody constant region comprises at least one amino acid selected from the group consisting of phenylalanine (F), tryptophan (W), histidine (H), glycine (G), valine (V), methionine (M), and alanine (A), at one or more positions selected from the group consisting of positions 351 and 394.

2. The protein complex of claim 1, wherein the first CH3 antibody constant region comprises at least one amino acid selected from the group consisting of phenylalanine (F), tryptophan (W), histidine (H), glycine (G), valine (V), methionine (M), and alanine (A), at one or more positions selected from the group consisting of positions 351 and 394.

3. The protein complex of claim 1, wherein the second CH3 antibody constant region comprises at least one amino acid selected from the group consisting of phenylalanine (F), tryptophan (W), histidine (H), glycine (G), valine (V), methionine (M), and alanine (A), at one or more positions selected from the group consisting of positions 351 and 394.

4. The protein complex of claim 1, wherein the first CH3 antibody constant region comprises tryptophan (W) at position 366 and phenylalanine (F), histidine (H) or tryptophan (W) at position 394.

5. The protein complex of claim 1, wherein the first CH3 antibody constant region comprises tryptophan (W) at position 366 and valine (V), tryptophan (W), alanine (A) or phenylalanine (F) at position 351.

6. The protein complex of claim 1, wherein the second CH3 antibody constant region comprises serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and alanine (A), glycine (G), valine (V), methionine (M), or phenylalanine (F) at position 351.

7. The protein complex of claim 1, wherein the first CH3 antibody constant region comprises one selected from the group consisting of: tryptophan (W) at position 366; tryptophan (W) at position 366, and histidine (H) at position 394; tryptophan (W) at position 366 and phenylalanine (F) at position 394; tryptophan (W) at position 366 and tryptophan (W) at position 394; tryptophan (W) at position 366 and phenylalanine (F) at position 351; tryptophan (W) at position 366 and tryptophan (W) at position 351; tryptophan (W) at position 366 and valine (V) at position 351; tryptophan (W) at position 366 and alanine (A) at position 351; and tryptophan (W) at position 366, histidine at position 394 (H), and phenylalanine at position 351 (F).

8. The protein complex of claim 1, wherein the second CH3 antibody constant region comprises one selected from the group consisting of: serine (S) at position 366, alanine (A) at position 368, and valine (V) at position 407; serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and alanine (A) at position 351; serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and glycine (G) at position 351; serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and valine (V) at position 351; serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and methionine (M) at position 351; and serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and phenylalanine (F) at position 351.

9. The protein complex of claim 1, wherein the first CH3 antibody constant region comprises tryptophan (W) at position 366 and phenylalanine (F), histidine (H) or tryptophan (W) at position 394; and the second CH3 antibody constant region comprises serine (S) at position 366, alanine (A) at position 368, and valine (V) at position 407.

10. The protein complex of claim 1, wherein the first CH3 antibody constant region comprises tryptophan (W) at position 366 and phenylalanine (F) at position 351; and the second CH3 antibody constant region comprises serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and alanine (A) at position 351.

11. The protein complex of claim 10, wherein the first CH3 antibody constant region further comprises histidine (H) at position 394.

12. The protein complex of claim 1, wherein the first CH3 antibody constant region comprises tryptophan (W) at position 366; and the second CH3 antibody constant region comprises serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and glycine (G) at position 351.

13. The protein complex of claim 12, wherein the first CH3 antibody constant region further comprises phenylalanine (F) or tryptophan (W) at position 351.

14. The protein complex of claim 1, wherein the first CH3 antibody constant region comprises tryptophan (W) at position 366; and the second CH3 antibody constant region comprises serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and alanine (A), valine (V) or methionine (M) at position 351.

15. The protein complex of claim 1, wherein the first CH3 antibody constant region comprises tryptophan (W) at position 366; and the second CH3 antibody constant region comprises serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and phenylalanine (F) at position 351.

16. The protein complex of claim 1, wherein the first CH3 antibody constant region comprises tryptophan (W) at position 366 and valine (V) at position 351; and the second CH3 antibody constant region comprises serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and alanine (A) at position 351.

17. The protein complex of claim 1, wherein the first CH3 antibody constant region comprises tryptophan (W) at position 366 and alanine (A) at position 351; and the second CH3 antibody constant region comprises serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and phenylalanine (F) at position 351.

18. The protein complex of claim 1, comprising any one selected from the group consisting of an antigen-binding fragment (Fab), a single chain variable fragment (scFv), an extracellular domain of a membrane receptor, an agonist, an antagonist, a ligand, a decoy receptor, a cytokine, a coagulation factor, and an affinity tag.

19. A protein complex comprising: a first polypeptide including a first CH3 antibody constant region; and a second polypeptide including a second CH3 antibody constant region, wherein the first polypeptide and the second polypeptide form a heterodimer, wherein the first CH3 antibody constant region comprises serine (S) at position 366, alanine (A) at position 368, and valine (V) at position 407, the second CH3 antibody constant region comprises a tryptophan (W) at position 366, and at least one of the first CH3 antibody constant region and the second CH3 antibody constant region comprises at least one amino acid selected from the group consisting of phenylalanine (F), tryptophan (W), histidine (H), glycine (G), valine (V), methionine (M), and alanine (A) at one or more positions selected from the group consisting of positions 351 and 394.

20. The protein complex of claim 19, wherein the first CH3 antibody constant region comprises serine (S) at position 366, alanine (A) at position 368, valine (V) at position 407, and glycine (G) at position 351; and the second CH3 antibody constant region comprises tryptophan (W) at position 366.

21. The protein complex of claim 20, wherein the second CH3 antibody constant region further comprises phenylalanine (F) or tryptophan (W) at position 351.

22. A method of preparing a protein complex, comprising: transforming one or more cells with one or more expression vectors encoding the first polypeptide of claim 1, or the second polypeptide of claim 1, or a combination thereof; and expressing the first polypeptide, or the second polypeptide, or a combination thereof.

23. The method of claim 22, wherein the expression vector encoding the first polypeptide and the expression vector encoding the second polypeptide are co-transfected into cells, or the expression vector encoding the first polypeptide and the expression vector encoding the second polypeptide are transformed into at least two types of cells, respectively.

24. The method of claim 22, comprising: obtaining a protein complex of the first polypeptide, the second polypeptide, or the first polypeptide and the second polypeptide, from the cells or a cell culture medium.

25. The method of claim 22, wherein the protein complex comprises one selected from the group consisting of an antigen-binding fragment (Fab) thereof, a single chain variable fragment (scFv), an extracellular domain of a membrane receptor, an agonist, an antagonist, a ligand, a decoy receptor, a cytokine, a coagulation factor, and an affinity tag.

26. A pharmaceutical composition for preventing or treating cancer, comprising the protein complex of claim 1.

27. A method of preventing or treating cancer, comprising: administering the protein complex of claim 1 to a cell or an organism.

28. A use of the protein complex of claim 1 for preparing a preventive or therapeutic agent for cancer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0090] FIG. 1 is an image showing results of SDS-PAGE analysis of Fc variants (M: size marker, WT: PTCWT (negative control group), 019: PTC019 (positive control group), 039: PTC039, 040: PTC040, 074: PTC074, 111: PTC111).

[0091] FIG. 2 is a graph showing results of capillary electrophoresis-SDS (CE-SDS) analysis of Fc variants.

[0092] FIGS. 3A to 3F are graphs showing results of size exclusion-high-performance liquid chromatography (SE-HPLC) analysis of PTCWT, PTC019, PTC039, PTC040, PTC074, and PTC111, respectively.

[0093] FIG. 4 is an image showing results of SDS-PAGE analysis of reverse sequence substitution Fc variants (M: size marker, WT: PTCWT (negative control group), 019: PTC019 (positive control group), 088: PTC088, 089: PTC089, 090: PTC090).

[0094] FIG. 5 is an image showing results of SDS-PAGE analysis of Fc variants in which a portion of the sequence is substituted (M: size marker, WT: PTCWT (negative control group), 019: PTC019 (positive control group), 074: PTC074, 097: PTC097, 098: PTC098, 099: PTC099, 111: PTC111, 113: PTC113).

[0095] FIG. 6 is an image showing results of SDS-PAGE analysis of Fab-Fc×scFv-Fc biconjugates (M: size marker, WT: Fab-Fc×scFv-Fc biconjugate with a PTCWT sequence applied to a CH3 domain (negative control group), 019: Fab-Fc×scFv-Fc biconjugate with a PTC019 sequence applied to a CH3 domain (positive control group), 074: Fab-Fc×scFv-Fc biconjugate with a PTC074 sequence applied to a CH3 domain).

[0096] FIG. 7 is an image showing results of SDS-PAGE analysis of Fab-Fc×scFv-scFv-Fc biconjugates (M: size marker, WT: Fab-Fc×scFv-scFv-Fc biconjugate with a PTCWT sequence applied to a CH3 domain (negative control group), 019: Fab-Fc×scFv-scFv-Fc biconjugate with a PTC019 sequence applied to a CH3 domain (positive control group), 074: Fab-Fc×scFv-scFv-Fc biconjugate with a PTC074 sequence applied to a CH3 domain).

[0097] FIG. 8 is an image showing results of SDS-PAGE analysis of Fab-Fc×cytokine-Fc biconjugates (M: size marker, WT: Fab-Fc×cytokine-Fc biconjugate with a PTCWT sequence applied to a CH3 domain (negative control group), 019: Fab-Fc×cytokine-Fc biconjugate with a PTC019 sequence applied to a CH3 domain (positive control group), 074: Fab-Fc×cytokine-Fc biconjugate with a PTC074 sequence applied to a CH3 domain).

[0098] FIG. 9 is a graph evaluating the ability of anti-PD-L1×anti-CD3 scFv bispecific antibodies to induce cancer cell death in vitro (Avelumab: positive control group, anti-PD-L1×anti-CD3 scFv BsAb: anti-PD-L1×anti-CD3 scFv bispecific antibody having a PTC074 sequence in a CH3 domain).

[0099] FIG. 10 is a graph evaluating the ability of anti-PD-L1×anti-CD3 scFv bispecific antibodies to inhibit cancer cell growth in vivo (Avelumab: positive control group, anti-PD-L1×anti-CD3 scFv BsAb: anti-PD-L1×anti-CD3 scFv bispecific antibody having a PTC074 sequence in a CH3 domain).

DETAILED DESCRIPTION OF THE INVENTION MODE OF DISCLOSURE

[0100] Hereinafter, preferred examples are presented to help gain a better understanding of the present disclosure. However, the following examples are only provided for easier understanding of the present disclosure, and the contents of the present disclosure are not limited by the following examples.

EXAMPLES

Example 1. Preparation of Fc Heterodimer Variants

[0101] In order to evaluate Fc heterodimer-forming ability, which is changed due to amino acid substitution in a CH3 domain of an antibody, an expression system for each designed Fc variant was constructed.

[0102] In order to facilitate distinction and analysis of the two Fc polypeptides constituting a heterodimer, the first polypeptide was designed to express an IgG chain (Fc1) of an intact form, in which both the heavy chain and the light chain are linked, and the second polypeptide was designed to express only the heavy chain Fc region (Fc2). In Fc1, amino acids in a CH3 domain were substituted based on an Avelumab antibody (Bavencio®, Pfizer) including a wild-type IgG1 Fc region, and in Fc2, amino acids in the CH3 domain were substituted based on a Fc region of a wild-type IgG1 antibody. The Fc1 light chain has the same amino acid sequence as the light chain of an Avelumab antibody (SEQ ID NO: 2).

[0103] For comparison, the wild-type IgG1 (corresponding to “PTCWT” in Table 1) was used as a negative control group, and Genentech's knobs-into-hole (KiH) bispecific antibody (corresponding to “PTC019” in Table 1) was used as a positive control group.

[0104] Specifically, expression vectors were prepared by introducing a nucleotide open reading frame (ORF) encoding each polypeptide into pCHO1.0 vectors. An ExpiCHO-S™ (Thermo Fisher) cell line was cultured in ExpiCHO™ expression medium. Fc1 expression vectors and Fc2 expression vectors were mixed at a ratio of 1:1 and transfected into the ExpiCHO-S™ cell line by using an ExpiFectamie™ CHO Transfection Kit (Thermo Fisher). After culturing the transfected cells in an expression medium, the culture medium was separated and recovered. The recovered culture medium was purified by using a Protein A HP SpinTrap™ column (GE Healthcare). For the purified protein, the buffer was exchanged with PBS (pH 7.4), and the protein concentration was measured.

[0105] The expressed amino acid sequences were as described below.

[0106] [PTCWT]

TABLE-US-00001 Fc1 heavy chain: (SEQ ID NO: 1) EVQLLESGGG LVQPGGSLRL SCAASGFTFS SYIMMWWRQA PGKGLEWVSS IYPSGGITFY ADTVKGRFTI SRDNSKNTLY LQMNSLRAED TAVYYCARIK LGTVTTVDYW GQGTLVTVSS ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT YICNVNHKPS NTKVDKKVEP KSCDKTHTCP PCPAPELLGG PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSRDE LTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT QKSLSLSPGK (Bold: L351, bold and underlined: T366) Fc1 light chain: (SEQ ID NO: 2) QSALTQPASV SGSPGQSITI SCTGTSSDVG GYNYVSWYQQ HPGKAPKLMI YDVSNRPSGV SNRFSGSKSG NTASLTISGL QAEDEADYYC SSYTSSSTRV FGTGTKVTVL GQPKANPTVT LFPPSSEELQ ANKATLVCLI SDFYPGAVTV AWKADGSPVK AGVETTKPSK QSNNKYAASS YLSLTPEQWK SHRSYSCQVT HEGSTVEKTV APTECS Fc chain of Fc2: (SEQ ID NO: 3) EPKSCDKTHTCPPCP APELLGGPSV FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSRDELTK NQVSLTCLVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS DGSFFLYSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS LSLSPGK (Bold: L351, bold and underlined: T366, underlined: L368, italic: Y407) [PTC019] Fc1 heavy chain: (SEQ ID NO: 4) EVQLLESGGG LVQPGGSLRL SCAASGFTFS SYIMMWVRQA PGKGLEWVSS IYPSGGITFY ADTVKGRFTI SRDNSKNTLY LQMNSLRAED TAVYYCARIK LGTVTTVDYW GQGTLVTVSS ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT YICNVNHKPS NTKVDKKVEP KSCDKTHTCP PCPAPELLGG PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSRDE LTKNQVSLWC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT QKSLSLSPGK (Bold: L351, bold and underlined: T366W) (SEQ ID NO: 2) Fc1 light chain Fc chain of Fc2: (SEQ ID NO: 5) EPKSCDKTHTCPPCP APELLGGPSV FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK CKVSNKALPA PIEKTISKAK GQPREPQVYT LPPSRDELTK NQVSLSCAVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS DGSFFLVSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS LSLSPGK (Bold: L351, bold and underlined: T366S, underlined: L368A, italic: Y407V) [PTC039] Fc1 heavy chain: (SEQ ID NO: 6) EVQLLESGGG LVQPGGSLRL SCAASGFTFS SYIMMWVRQA PGKGLEWVSS IYPSGGITFY ADTVKGRFTI SRDNSKNTLY LQMNSLRAED TAVYYCARIK LGTVTTVDYW GQGTLVTVSS ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT YICNVNHKPS NTKVDKKVEP KSCDKTHTCP PCPAPELLGG PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTFPPSRDE LTKNQVSLWC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT QKSLSLSPGK (Bold: L351F, bold and underlined: T366W) (SEQ ID NO: 2) Fc1 light chain Fc chain of Fc2: (SEQ ID NO: 7) EPKSCDKTHTCPPCP APELLGGPSV FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK CKVSNKALPA PIEKTISKAK GQPREPQVYT GPPSRDELTK NQVSLSCAVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS DGSFFLVSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS LSLSPGK  (Bold: L351G, bold and underlined: T366S, underlined: L368A, italic: Y407V) [PTC040] Fc1 heavy chain: (SEQ ID NO: 8) EVQLLESGGG LVQPGGSLRL SCAASGFTFS SYIMMWVRQA PGKGLEWVSS IYPSGGITFY ADTVKGRFTI SRDNSKNTLY LQMNSLRAED TAVYYCARIK LGTVTTVDYW GQGTLVTVSS ASTKGPSVFP LAPSSKSTSG GTAALGCLVK DYFPEPVTVS WNSGALTSGV HTFPAVLQSS GLYSLSSVVT VPSSSLGTQT YICNVNHKPS NTKVDKKVEP KSCDKTHTCP PCPAPELLGG PSVFLFPPKP KDTLMISRTP EVTCVVVDVS HEDPEVKFNW YVDGVEVHNA KTKPREEQYN STYRVVSVLT VLHQDWLNGK EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTWPPSRDE LTKNQVSLWC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV LDSDGSFFLY SKLTVDKSRW QQGNVFSCSV MHEALHNHYT QKSLSLSPGK (Bold: L351W, bold and underlined: T366W) Fc1 light chain (SEQ ID NO: 2) Fc chain of Fc2 (SEQ ID NO: 7) [PTC074] Fc1 heavy chain (SEQ ID NO: 4) Fc1 light chain (SEQ ID NO: 2) Fc chain of Fc2 (SEQ ID NO: 7) [PTC111] (SEQ ID NO: 4) Fc1 heavy chain (SEQ ID NO: 2) Fc1 light chain Fc chain of Fc2: (SEQ ID NO: 9) EPKSCDKTHTCPPCP APELLGGPSV FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QDWLNGKEYK CKVSNKALPA PIEKTISKAK GQPREPQVYT FPPSRDELTK NQVSLSCAVK GFYPSDIAVE WESNGQPENN YKTTPPVLDS DGSFFLVSKL TVDKSRWQQG NVFSCSVMHE ALHNHYTQKS LSLSPGK  (Bold: L351F, bold and underlined: T366S, underlined: L368A, italic: Y407V)

Example 2. Comparison of Heterodimer-Forming Abilities of Fc Variants

[0107] Using the transient expression system constructed in Example 1 above, abilities to form Fc heterodimers, which are changed due to amino acid substitution of the CH3 domain, were compared, and thereby, high-efficiency Fc heterodimer variants were selected.

[0108] As an evaluation method, after performing non-reducing SDS-PAGE, the intensity of the PAGE bands corresponding to the heterodimers were measured and compared.

[0109] Specifically, the protein purified in Example 1 was reduced by 2-mercaptoethanol, or a sample without the 2-mercaptoethanol treatment was prepared. The reduced or non-reduced sample was electrophoresed by a SDS-PAGE method, and the intensity of the electrophoretic band was measured by using a ChemiDoc™ Imaging System (Bio-Rad) and Image Lab™ Software (Bio-Rad).

[0110] The Fc heterodimer formation ability according to the amino acid substitution of the CH3 domain was calculated with the measured band intensities, and the results are shown in Table 1 below.

TABLE-US-00002 TABLE 1 Mutation of amino Mutation of amino Expression Heterodimer Number acid Fc1 acid Fc2 level (mg/L) ratio (%) PTCWT — — 269.5 ± 9.7 41.5 (negative control group) PTC019 T366W T366S, L368A, Y407V 183.3 ± 11.1 64.6 (positive control group) PTC023 L351F L351G 140.1 ± 4.8 27.2 PTC024 L351W L351A 112.3 ± 22.0 2.0 PTC025 L351W L351G 100.0 ± 18.5 15.4 PTC031 T394W — 253.8 ± 11.2 29.5 PTC032 T366W, T394H T366S, L368A, Y407V 143.8 ± 40.0 78.7 PTC033 T366W, T394F T366S, L368A, Y407V 162.7 ± 20.0 76.4 PTC034 T366W, T394W T366S, L368A, Y407V 211.8 ± 10.9 76.1 PTC037 L351F, T366W L351A, T366S, L368A, 193.4 ± 77.5 85.8 Y407V PTC038 L351W, T366W L351A, T366S, L368A, 142.8 ± 6.7 63.1 Y407V PTC039 L351F, T366W L351G, T366S, L368A, 151.2 ± 13.7 93.8 Y407V PTC040 L351W, T366W L351G, T366S, L368A, 146.1 ± 34.7 94.6 Y407V PTC053 L351F, T394H L351A  46.1 ± 4.8 1.0 PTC054 L351F, T394F L351A  50.6 ± 5.7 1.1 PTC061 L351F, T366W, L351A, T366S, L368A,  73.2 ± 23.9 70.9 T394H Y407V PTC062 L351F, T366W, L351A, T366S, L368A,  32.7 ± 7.7 44.0 T394F Y407V PTC074 T366W L351G, T366S, L368A, 125.9 ± 13.9 94.9 Y407V PTC075 T366W, T394H L351G, T366S, L368A,  33.4 ± 6.6 21.9 Y407V PTC076 L351F, T366W, L351G, T366S, L368A,  34.9 ± 8.4 33.1 T394H Y407V PTC082 L351V, T366W L351A, T366S, L368A,  55.0 ± 3.4 79.3 Y407V PTC083 L351I, T366W L351A, T366S, L368A,  42.6 ± 5.1 <1 Y407V PTC091 T366W L351A, T366S, L368A,  52.1 ± 6.1 75.4 Y407V PTC111 T366W L351F, T366S, L368A,  55.8 ± 5.0 92.7 Y407V PTC112 T366W L351W, T366S, L368A,  30.9 ± 4.1 <1 Y407V PTC113 L351A, T366W L351F, T366S, L368A, 146.3 ± 6.3 82.8 Y407V PTC114 L351A, T366W L351W, T366S, L368A,  22.0 ± 5.6 <1 Y407V PTC115 L351G, T366W L351F, T366S, L368A,  79.4 ± 8.4 <1 Y407V PTC116 L351G, T366W L351W, T366S, L368A,  23.1 ± 5.7 <1 Y407V

[0111] As a result, as shown in Table 1, the heterodimer formation rates of the negative control group (PTCWT) and the positive control group (PTC019) were 41.5% and 64.6%, respectively, whereas it was confirmed that heterodimer formation rates of PTC032, PTC033, PTC034, PTC037, PTC039, PTC040, PTC061, PTC074, PTC082, PTC091, PTC111 and PTC113 were respectively 78.7%, 76.4%, 76.1%, 85.8%, 93.8%, 94.6%, 70.9%, 94.9%, 79.3%, 75.4%, 92.7%, and 82.8%. In particular, it was confirmed that PTC039, PTC040, PTC074 and PTC111 had a ratio of Fc heterodimers exceeding 90%.

[0112] That is, an Fc variant according to an aspect may exhibit very excellent Fc heterodimer formation ability.

Example 3. Evaluation of Heterodimer-Forming Abilities of High Efficiency Fc Variants

[0113] 3-1. SDS-PAGE Analysis

[0114] In order to evaluate heterodimer-forming abilities of the high-efficiency Fc variants selected in Example 2, SDS-PAGE analysis was performed in the same manner as in Example 2.

[0115] Specifically, intensities of the electrophoretic bands were measured from SDS-PAGE analysis. Thereafter, rates of Fc heterodimer formation according to the amino acid substitution of the CH3 domain were confirmed with the intensity of the measured bands, and the results are shown in Table 2 below (N/A: Not applicable).

TABLE-US-00003 TABLE 2 Molecular Weight Note (kDa) PTCWT PTC019 PTC039 PTC040 PTC074 PTC111 Multimer N/A <1 <1 <1 <1 <1 <1 Fc1-1 homo-dimer 146.8 17.1 <1 2.1 1.1 0.7 <1 Fc1-2 hetero-dimer 99.3 41.5 64.6 93.8 94.6 94.9 92.7 Fc1 monomer 73.4 1.5 2.4 3.3 3.4 3.6 5.2 Fc-2-2 homo-dimer 51.8 39.9 13.3 <1 <1 <1 <1 Fc2 monomer 25.9 <1 19.7 <1 <1 <1 <1 Free light chain 23.7 <1 <1 <1 <1 <1

[0116] FIG. 1 is an image showing results of SDS-PAGE analysis of Fc variants.

[0117] As a result, as shown in FIG. 1, it was confirmed that the band intensity of the Fc1-1 homo-dimer (146.8 kDa) of the selected PTC039, PTC040, PTC074 and PTC111 was noticeably reduced compared to that of the negative control group (PTCWT), and the band intensity of the Fc2 monomer (25.9 kDa) was noticeably reduced compared to the positive control group (PTC019). On the other hand, it was confirmed that the Fc1-2 hetero-dimer was formed with high efficiency at 99.3 kDa.

[0118] In addition, as shown in Table 1, in cases of the negative control group (PTCWT) and the positive control group (PTC019), it was confirmed that not only the Fc1-2 hetero-dimer but also the Fc1-1 homo-dimer was formed at a rate of 17.1% with the negative control group (PTCWT), and Fc-2-2 homo-dimer was confirmed to be formed at a rate of 39.9% in the negative control group (PTCWT) and 13.3% in the positive control group (PTC019). On the other hand, in cases of the selected Fc variants of PTC039, PTC040, PTC074 and PTC111, it was confirmed that the formation rate of Fc1-1 homo-dimers and Fc-2-2 homo-dimers was low, and the formation rate of Fc1-2 hetero-dimers was noticeably higher.

[0119] That is, it may be seen that the Fc variant according to an aspect is capable of selectively forming Fc1-2 hetero-dimers.

[0120] 3-2. CE-SDS Analysis

[0121] In order to verify heterodimer-forming abilities of the high-efficiency Fc variants selected in Example 2, capillary electrophoresis-SDS (CE-SDS) analysis was performed.

[0122] Specifically, capillary electrophoresis was performed by using a PA 800 Plus™ pharmaceutical analysis system (SCIEX) to verify Fc heterodimer formation rates of the Fc variants, and the results are shown in Table 3 below.

TABLE-US-00004 TABLE 3 Molecular Weight Note (kDa) PTCWT PTC019 PTC039 PTC040 PTC074 PTC111 Fc1-1 homo-dimer 144.0 11.1 n.d. n.d. n.d. n.d. n.d. Fc1-2 hetero-dimer 98.0 40.1 60.1 81.0  80.2  83.8  84.8 Light chain free Fc1-2 75.2 4.8 2.5 3.8 7.7 8.5 6.6 hetero-dimer Fc1 monomer 71.9 0.5 0.3 1.0 1.4 0.6 0.4 Fc-2-2 homo-dimer 49.2 34.4 13.7 n.d. n.d. n.d. 0.6 Fc2 monomer 24.6 n.d. 20.3 11.3  7.5 2.4 2.0 Free light chain 22.8 2.5 0.4 1.8 2.3 2.7 2.0

[0123] FIG. 2 is a graph showing results of capillary electrophoresis-SDS (CE-SDS) analysis of Fc variants.

[0124] As a result, as shown in FIG. 2, at around 23 minutes of retention time, Fc-2-2 homo-dimer formation rate of the negative control group (PTCWT) was shown to be 34.44%, and Fc-2-2 homo-dimer formation rate of the positive control group (PTC019) was confirmed to be 13.71%. On the other hand, in cases of PCT039, PTC040, and PTC074, Fc-2-2 homo-dimer was not formed, and in case of PCT111, Fc-2-2 homo-dimer formation rate was 0.57%, and the rate was noticeably lower compared to that of the negative control group (PTCWT) and the positive control group (PCT019).

[0125] In addition, as shown in Table 2, heterodimer formation rates of PTC039, PTC040, PTC074 and PTC111 were 81.0%, 80.2%, 83.8% and 84.8%, respectively, and were significantly higher than that of the negative control group (PCTWT) and the positive control group (PTC019).

[0126] That is, it may be seen that the Fc variant according to an aspect has excellent heterodimer formation ability.

[0127] 3-3. SE-HPLC Analysis

[0128] In order to verify the heterodimer-forming abilities of the high-efficiency Fc variants selected in Example 2, size exclusion-high-performance liquid chromatography (SE-HPLC) analysis was performed, and the results are shown in Table 4 below.

TABLE-US-00005 TABLE 4 Retention time Note (min) PTCWT PTC019 PTC039 PTC040 PTC074 PTC111 Multimer 11.4 0.4 16.5 4.7 5.9 2.9 4.0 Fc1-1 homo-dimer 16.0 10.86 0.6 Fc1-2 hetero-dimer 17.0 42.16 58.24 90.76 87.51 90.59 91.6 Fc1 monomer N/A Fc-2-2 homo-dimer 18.4 46.03 13.13 1.5 0.96 2.7 Fc2 monomer 19.2 25.78 1.0 Free light chain 19.8

[0129] FIGS. 3A to 3F are graphs showing results of size exclusion-high-performance liquid chromatography (SE-HPLC) analysis of PTCWT, PTC019, PTC039, PTC040, PTC074, and PTC111, respectively.

[0130] As a result, as shown in FIGS. 3A to 3F, in SE-HPLC analysis of the protein purified with Protein A, main peaks of a heterodimer were observed at retention times of 16.989 minutes to 17.197 minutes in Fc variants including the negative control group (PTCWT) and the positive control group (PTC019). Specifically, in case of the negative control group (PTCWT), an Fc-1-1 homo-dimer peak was observed at a retention time of 16.079 minutes and an Fc2-2 homo-dimer peak was observed at 18.377 minutes (FIG. 3A). In addition, in case of the positive control group (PTC019), an Fc-2-2 homo-dimer peak was observed at a retention time of 18.343 minutes and an Fc-2 monomer peak was observed at 19.14 minutes (FIG. 3B). That is, in case of the negative control group (PTCWT) and the positive control group (PCT019), heterodimer formation rate was confirmed to be low as multiple peaks including the Fc1-2 hetero-dimer were shown, on the other hand, in case of the Fc variants of PTC039, PTC040, PTC074 and PTC111, the main peak was observed in a form of a single peak. That is, in case of the selected Fc variants, heterodimer formation rate was confirmed to be excellent compared to that of the negative control group (PTCWT) and the positive control group (PTC019).

[0131] In addition, as shown in Table 4, it was confirmed that the selected Fc variants of PTC039, PTC040, PTC074 and PTC111 had better heterodimer formation abilities compared to the two control groups of PTCWT and PTC019.

[0132] Therefore, the Fc variant according to an aspect may form a heterodimer with high efficiency, and thus bispecific antibodies may be easily prepared.

Example 4. Evaluation of Thermodynamic Stability of High-Efficiency Fc Variant Heterodimers

[0133] In order to indirectly confirm structural stabilities of the heterodimers of the high-efficiency Fc variants identified in Example 3, a thermodynamic stability evaluation was performed by using differential scanning calorimetry (DSC).

[0134] Specifically, thermal stabilities of the selected Fc variants were measured by using Nano DSC™ (TA instruments), and melting temperatures (Tm, ° C.) were calculated. The calculated melting points of the Fc variants are shown in Table 5 below.

TABLE-US-00006 TABLE 5 Tm (° C.) Fc variant CH3 CH2 Fab PTCWT 82.75 69.01 71.88 PTC019 70.82 57.14 71.82 PTC039 77.51 65.92 69.63 PTC040 77.75 66.63 69.82 PTC074 77.72 66.84 69.68 PTC111 76.87 70.36 71.54

[0135] As a result, as shown in Table 5, it was confirmed that the selected Fc variants of PTC039, PTC040, PTC074 and PTC111 had somewhat unstable thermal stability compared to the wild-type Fc heterodimer (PTCWT), but had relatively high thermodynamic stability compared to the KiH Fc heterodimer (PTC019) of Genentech.

[0136] That is, the Fc variant according to an aspect has excellent heterodimer-forming ability as well as excellent thermodynamic stability, thus, formation of stable bispecific antibodies is possible.

Example 5. Comparison of Heterodimer-Forming Abilities of Variants Substituted with Reverse-Sequence in CH3 Domain of High-Efficiency Fc Variants

[0137] In order to evaluate heterodimer-forming abilities of variants substituted with reverse-sequence in CH3 domain of high-efficiency Fc variants selected in Example 3 above, SDS-PAGE analysis was performed in the same manner as in Example 2.

[0138] Fc heterodimer formation abilities according to the amino acid substitution in the CH3 domain were calculated with the band intensities measured from SDS-PAGE analysis, and the results are shown in Table 6 below.

TABLE-US-00007 TABLE 61 Mutation of Mutation of amino amino Expression Heterodimer Number acid Fc1 acid Fc2 level (mg/L) ratio (%) PTCWT — — 147.2 ± 37.7 40.9 (negative control group) PTC019 T366W T366S, L368A, 118.3 ± 39.6 64.7 (positive Y407V control group) PTC088 L351G, T366S, L351F, T366W 102.1 ± 20.2 72.1 L368A, Y407V PTC089 L351G, T366S, L351W, T366W  92.2 ± 8.9 83.3 L368A, Y407V PTC090 L351G, T366S, T366W  41.5 ± 3.6 92.1 L368A, Y407V

[0139] FIG. 4 is an image showing results of SDS-PAGE analysis of reverse sequence substitution Fc variants (M: size marker, WT: PTCWT (negative control group), 019: PTC019 (positive control group), 088: PTC088, 089: PTC089, 090: PTC090).

[0140] As a result, as shown in FIG. 4, it was confirmed that the reverse sequence substitution Fc variants did not form a band around 150 kDa compared to the negative control group (PTCWT), and a bands was weakly formed at 49.2 kDa. That is, it was confirmed that the reverse sequence substitution Fc variants did not form a Fc-1-1 homo-dimer, and formation of Fc-2-2 homo-dimers was reduced. In addition, it was confirmed that a band was weakly formed in the vicinity of 25 kDa compared to the positive control group (PCT019). That is, it may be seen that the reverse sequence substitution Fc variants have reduced Fc-2 monomer formation, and show heterodimer formation rates similar to that of PTC039, PTC040, and PTC074 (see FIG. 1).

[0141] In addition, as shown in Table 6, the heterodimer formation rates of the negative control group (PTCWT) and the positive control group (PTC019) were shown to be 40.9% and 64.7%, respectively, whereas it was confirmed that PTC088, PTC089 and PTC090, which are reverse sequence substitution Fc variants of PTC039, PTC040 and PTC074, exhibited heterodimer formation rates of 72.1%, 83.3% and 92.1%, respectively.

[0142] Therefore, it may be seen that the reverse sequence substitution variants of the Fc variant according to an aspect forms a heterodimer in a similar ratio before and after substitution. In addition, since the reverse sequence substitution variants of the Fc variants have an excellent heterodimer formation rate, Fc variants may be formed with high efficiency regardless of whether the sequence inserted into Fc1 or Fc2 is substituted or not.

Example 6. Comparison of Heterodimer-Forming Abilities of Fc Variants with Sequence Change at Position 351 of CH3 Domain

[0143] In order to evaluate heterodimer-forming ability of variants, in which the position 351 of the CH3 domain is substituted with an amino acid having similar properties, like PTC074 and PTC111, which are high-efficiency Fc variants selected in Example 3, SDS-PAGE analysis was performed in the same manner as in Example 2.

[0144] Fc heterodimer-forming abilities according to the amino acid substitution in the CH3 domain were calculated with the intensity of the bands measured from SDS-PAGE analysis, and the results are shown in Table 7 below.

TABLE-US-00008 TABLE 7 Mutation of Mutation of amino amino Expression Heterodimer Number acid Fc1 acid Fc2 level (mg/L) ratio (%) PTCWT — — 54.4 ± 5.6 40.2 (negativ e control group) PTCO19 T366W T366S,L368A, 51.1 ± 5.6 79.7 (positive Y407V control group) PTCO74 T366W L351G,T366S, 40.4 ± 4.1 93.5 L368A, Y407V PTCO97 T366W L351V,T366S, 39.8 ± 9.9 82.7 L368A, Y407V PTCO98 T366W L351S,T366S, 26.4 ± 12.7 76.8 L368A, Y407V PTCO99 T366W L351M,T366S, 20.9 ± 1.9 86.5 L368A, Y407V PTC111 T366W L351F,T366S, 55.8 ± 5.0 92.7 L368A, Y407V PTC112 T366W L351W,T366S, 30.9 ± 4.1 <1 L368A, Y407V

[0145] FIG. 5 is an image showing results of SDS-PAGE analysis of Fc variants, in which a portion of the sequence is substituted (M: size marker, WT: PTCWT (negative control group), 019: PTC019 (positive control group), 074: PTC074, 097: PTC097, 098: PTC098, 099: PTC099, 111: PTC111, 113: PTC113).

[0146] As a result, as shown in FIG. 5, in cases of PTC074 and PTC111, it was confirmed that a band was not formed around 150 kDa compared to the negative control group (PTCWT), and compared to the positive control group (PTC019), intensity of the bands at 49.2 kDa and 24.6 kDa were noticeably reduced. In addition, it was confirmed that the intensity of the bands at 24.6 kDa was noticeably reduced compared to PTC097, PTC098, and PTC099, in which the sequence is substituted at position 351 of Fc-2. On the other hand, it was confirmed that the intensity of the band increased at 98 kDa, which is the expected molecular weight of the Fc-1-2 heterodimer.

[0147] In addition, as shown in Table 7, the heterodimer formation rates of PTC074, PTC097, PTC099 and PTC111 were shown to be 93.5%, 82.7%, 86.5%, and 92.7%, respectively, and were confirmed to be significantly higher than that of the negative control group (PCTWT) and the positive control group (PTC019). In particular, in cases of PTC074 and PTC111, in which the position 351 of the CH3 domain was substituted with glycine (G) or phenylalanine (F), it was confirmed that the Fc heterodimer formation rate exceeded 90%.

[0148] That is, it may be seen that the Fc variant according to an aspect has excellent Fc heterodimer-forming ability by substituting the position 351 of the CH3 domain with a specific amino acid.

Example 7. Evaluation of Heterodimer-Forming Ability of Bispecific Antibodies Including High-Efficiency Fc Variants

[0149] 7-1. Fab-Fc×scFv-Fc Bispecific Antibody

[0150] In order to evaluate heterodimer formation rate of the hetero-bispecific antibody including the high-efficiency Fc variants selected in Example 3, the first polypeptide was designed to express an IgG chain (Fc1) of an intact form, in which both the heavy chain and the light chain are linked, and the second polypeptide was designed to express a scFV-Fc form (Fc2). Thereafter, expression of Fc1 was proceeded based on an Avelumab antibody (Bavencio, Pfizer) including an IgG1 Fc region, and Fc2 was expressed in a scFv form including an IgG1 Fc region based on an anti-CD3 scFv sequence of blinatumomab.

[0151] For comparison, a Fab-Fc×scFv-Fc hetero-bispecific antibody, in which anti-CD3 scFv of blinatumomab is bound to Fc2 of an Fc variant having a wild-type CH3 domain sequence (corresponding to “PTCWT” in Table 1), was used as a negative control group, and a Fab-Fc×scFv-Fc hetero-bispecific antibody, in which anti-CD3 scFv of blinatumomab is bound to Fc2 of an Fc variant (corresponding to “PTC019” in Table 1) having Genentech's knobs-into-hole (KiH) sequence in the CH3 domain, was used as a positive control group.

[0152] Expression of each test substance was carried out by using the transient expression system constructed in Example 1, and after performing non-reducing SDS-PAGE, the intensities of the PAGE bands corresponding to the heterodimers were measured to compare the rates of heterodimer formation.

[0153] Fc heterodimer formation ability according to the amino acid substitution of the CH3 domain was calculated with the measured band intensity, and the results are shown in Table 8 below.

TABLE-US-00009 TABLE 8 CH3 domain sequence of Fab-Fc × scFv-Fc hetero- Molecular bispecific antibody Note Weight (kDa) PTCWT PTC019 PTC074 Fc1-1 homo-dimer 144.0 17.6 <1 <1 Fd-2 hetero-dimer 124.4 45.4 75.8 88.8 Fc-2-2 homo-dimer 104.8 37.0 19.6 7.0 Light chain free Fc1-2 101.6 <1 <1 <1 hetero-dimer Fc 2 or Fc 1 heavy chain ~50 <1 4.6 4.2

[0154] FIG. 6 is an image showing results of SDS-PAGE analysis of Fab-Fc×scFv-Fc biconjugates (M: size marker, WT: Fab-Fc×scFv-Fc biconjugate with a PTCWT sequence applied to the CH3 domain (negative control group), 019: Fab-Fc×scFv-Fc biconjugate with a PTC019 sequence applied to the CH3 domain (positive control group), 074: Fab-Fc×scFv-Fc biconjugate with a PTC074 sequence applied to the CH3 domain).

[0155] As a result, as shown in FIG. 6, it was confirmed that the Fab-Fc×scFv-Fc hetero-bispecific antibody to which a PTC074 sequence was applied did not form a band at 144 kDa compared to the hetero-bispecific antibody to which a sequence of the negative control group (PTCWT) was applied. In addition, it was confirmed that the intensity of the band was reduced at 104.8 kDa compared to the hetero-bispecific antibody to which a PTC019 sequence was applied. On the other hand, at 124.4 kDa, which is the expected molecular weight of the complete Fab-Fc×scFv-Fc hetero-bispecific antibody, it was confirmed that the band intensity was increased compared to the negative control group (PCTWT) and the positive control group (PTC019).

[0156] In addition, as shown in Table 8, the Fc1-2 heterodimer formation rate of the Fab-Fc×scFv-Fc hetero-bispecific antibody, which has a CH3 domain sequence of PTC074, was 88.8%, and it was confirmed that the heterodimer formation rate was significantly higher than that of the negative control group (PTCWT) and the positive control group (PTC019).

[0157] That is, it may be seen that the Fc variant according to an aspect may be applied as a hetero-bispecific antibody structure that forms antibodies of different structures and has excellent heterodimer formation ability.

[0158] 7-2. Fab-Fc×scFv-scFv-Fc Bispecific Antibody

[0159] The rates of heterodimer formation were evaluated in the same manner as in Example 7-1, except that Fab-Fc×scFv-scFv-Fc bispecific antibodies designed to express the second polypeptide in a form of scFv-scFv-Fc (Fc2) were used, and Fc2 was expressed in a form of double scFv (scFv×scFv) including an IgG1 Fc region, based on the anti-CD3 scFv sequence of blinatumomab and the VH-VL sequence of Bevacizumab (Avastin, Roche).

[0160] For comparison, a Fab-Fc×scFv-scFv-Fc hetero-bispecific antibody, in which double scFv is bound to Fc2 of an Fc variant having a wild-type CH3 domain sequence (corresponding to “PTCWT” in Table 1), was used as a negative control group, and a Fab-Fc×scFv-scFv-Fc hetero-bispecific antibody, in which double scFv is bound to Fc2 of an Fc variant (corresponding to “PTC019” in Table 1) having Genentech's knobs-into-hole (KiH) sequence in the CH3 domain, was used as a positive control group.

TABLE-US-00010 TABLE 91 CH3 domain sequence of Fab-Fc × scFv-scFv-Fc Molecular hetero-bispecific antibody Note Weight (kDa) PTCWT PTC019 PTC074 Fc2-2 homo-dimer 196.0 9.7 5.6 <1 Fc1-2 hetero-dimer 167.8 42.0 57.6 70.2 Fc-1-1 homo-dimer 161.7 37.0 <1 <1 Unknown 1 159.1 <1 3.5 2.6 Unknown 2 ~140~150 11.3 15.7 19.0 Unknown 3 112.9 <1 2.8 3.4 Fc 1 or 2 monomer ~70~80 <1 14.7 4.7

[0161] FIG. 7 is an image showing results of SDS-PAGE analysis of Fab-Fc×scFv-scFv-Fc biconjugates (M: size marker, WT: Fab-Fc×scFv-scFv-Fc biconjugate with a PTCWT sequence applied to the CH3 domain (negative control group), 019: Fab-Fc×scFv-scFv-Fc biconjugate with a PTC019 sequence applied to the CH3 domain (positive control group), 074: Fab-Fc×scFv-scFv-Fc biconjugate with a PTC074 sequence applied to the CH3 domain).

[0162] As a result, as shown in FIG. 7, the Fab-Fc×scFv×scFv-Fc biconjugate to which a PTC074 sequence was applied was confirmed to have a noticeably decreased intensity of the 196 kDa band compared to the conjugate to which the negative control group (PTCWT) and the positive control group (PTC019) sequences were applied. In addition, since the band intensities were reduced, except in the band of the heterodimer shown in the biconjugate to which a positive control group (PTC019) sequence was applied, it was confirmed that the target Fc 1-2 hetero-dimer of 167.8 kDa was formed with high efficiency.

[0163] In addition, as shown in Table 9, the Fc1-2 heterodimer formation rate of the Fab-Fc×scFv-scFv-Fc hetero-bispecific antibody having a CH3 domain sequence of PTC074 was 70.2%, and it was confirmed that the heterodimer formation rate was significantly higher than that of the negative control group (PTCWT) and the positive control group (PTC019).

[0164] That is, it may be seen that the Fc variant according to an aspect is not only easy to apply as a hetero-bispecific antibody structure having a large molecular weight structure because several structures are connected, but also has excellent heterodimer formation when applied as the structure.

[0165] 7-3. Fab-Fc×Cytokine-Fc Bispecific Antibody

[0166] The rates of heterodimer formation were evaluated in the same manner as in Example 7-1, except that Fab-Fc×cytokine-Fc bispecific antibodies designed to express the second polypeptide in a form of cytokine-Fc (Fc2) were used, and expression of Fc2 was proceeded in a form of a cytokine including an IgG1 Fc region, which is based on interleukine-2 (IL-2, aldesleukine) sequence.

[0167] For comparison, a Fab-Fc×IL-2v-Fc hetero-bispecific antibody, in which an IL-2 variant (IL-2v) is bound to Fc2 of an Fc variant having a wild-type CH3 domain sequence (corresponding to “PTCWT” in Table 1), was used as a negative control group, and a Fab-Fc×IL-2v-Fc hetero-bispecific antibody, in which an IL-2 variant (IL-2v) is bound to Fc2 of an Fc variant (corresponding to “PTC019” in Table 1) having Genentech's knobs-into-hole (KiH) sequence in the CH3 domain, was used as a positive control group.

TABLE-US-00011 TABLE 10 CH3 domain sequence of Molecular Fab-Fc × cytokine-Fc Weight hetero-bispecific antibody Note (kDa) PTCWT PTC019 PTC074 PTC111 Fc1-1 homo- 187.4 <1 <1 <1 <1 dimer Fc1-2 hetero- 136.5 40.6 68.8 90.4 89.9 dimer Fc-2-2 homo- 94.4 27.1 16.5 <1 <1 dimer Fc1 monomer 77.4 32.3 <1 <1 <1 Fc 2 monomer 41.0 <1 14.6 5.4 6.0

[0168] FIG. 8 is an image showing results of SDS-PAGE analysis of Fab-Fc×cytokine-Fc biconjugates (M: size marker, WT: Fab-Fc×cytokine-Fc biconjugate with a PTCWT sequence applied to the CH3 domain (negative control group), 019: Fab-Fc×cytokine-Fc biconjugate with a PTC019 sequence applied to the CH3 domain (positive control group), 074: Fab-Fc×cytokine-Fc biconjugate with a PTC074 sequence applied to the CH3 domain).

[0169] As a result, as shown in FIG. 8, it was confirmed that the Fab-Fc×cytokine-Fc biconjugate to which PTC074 and PTC111 sequences were applied had a reduced band intensity at 94.4 kDa (Fc-2-2 homo-dimer) and 77.4 kDa (Fc1 monomer), and the band intensity increased at 136.5 kDa (Fc-1-2 hetero-dimer), compared to the negative control group (PTCWT) or the positive control group (PTC019). Therefore, in the Fab-Fc×cytokine-Fc biconjugate to which PTC074 and PTC111 sequences were applied, formation of a Fc-2-2 homo-dimer band and Fc-1 monomers were reduced, and thus, it may be seen that Fc-1-2 hetero-dimers were formed with high efficiency.

[0170] In addition, as shown in Table 10, according to the structure in which sequences of the negative control group (PTCWT), positive control group (PTC019), PTC074, and PTC111 are reflected in the Fab-Fc×Cytokine-Fc biconjugate, the ratio of Fc-1-2 heterodimers was 40.6%, 68.8%, 90.4%, and 89.9%, respectively, and it was confirmed that the biconjugates reflecting PTC074 and PTC111 had a significantly higher heterodimer formation rate, compared to the negative control group (PTCWT) and the positive control group (PTC019).

[0171] That is, it may be seen that the Fc variant according to an aspect may be applied as a structure that forms an antibody, and when a cytokine protein is applied, heterodimer forming ability is excellent.

[0172] 7-4. Fab-Fc×Fab-Fc Bispecific Antibody

[0173] In order to evaluate heterodimer formation rates of the hetero-bispecific antibodies including the high-efficiency Fc variants selected in Example 3, both the first polypeptide and the second polypeptide were designed to express bispecific antibodies of an intact form in which both heavy and light chains are linked. Specifically, Fc1 was expressed based on the Avelumab antibody (Bavencio, Pfizer) including the wild-type IgG1 Fc region, and Fc2 was expressed based on the bevacizumab antibody (Avastin, Roche) including the IgG1 Fc region.

[0174] For comparison, a Fab-Fc×Fab-Fc hetero-bispecific antibody including a Fc variant having the wild-type CH3 domain sequence (corresponding to “PTCWT” in Table 1) was used as a negative control group, and a Fab-Fc×Fab-Fc hetero-bispecific antibody including a Fc variant (corresponding to “PTC019” in Table 1) having Genentech's knobs-into-hole (KiH) sequence in the CH3 domain was used as a positive control group.

[0175] As an evaluation method, Intact MASS (ESI-LC-MS) analysis method was used. Specifically, liquid chromatography-mass spectrometry (LC-MS) was performed by using Thermo Scientific Dionex™ UHPLC Ultimate 3000 and TripleTOF 5600+(AB sciex), and Analyst® software and PeakView® Software were used as analysis programs to calculate the heterodimer-forming ability, and the results are shown in Table 11 below.

TABLE-US-00012 TABLE 11 Ratio (%) Measured CH3 domain sequence of Fab-Fc × Fab- value Fc hetero-bispecific antibody Note (m/z) PTCWT PTC019 PTC039 PTC040 PTC074 Fc1-2 hetero dimer 147,807~148,584 25.4 32.4 58.1 40.5 46.8 Fc1 or Fc 2 homo-dimer 147,921~149,245 25.2 7.6 9.5 14.7  7.6 Fc1 or Fc 2 monomer 74,497~74,926 — 60.0 23.7 35.1 — Free light chain 21,115~27,103 49.4 — 8.7 9.8 45.7

[0176] As shown in Table 11, it was confirmed that Fc-1-2 hetero-dimer formation rates of the Fab-Fc×Fab-Fc hetero-bispecific antibodies, to which sequences of the negative control group (PTCWT) and the positive control group (PTC019) were applied, were respectively 25.4% and 32.4%, on the other hand, Fc-1-2 hetero-dimer formation rates of the hetero-bispecific antibodies having a CH3 domain sequences of PTC039, PTC040, and PTC074 were 58.1%, 40.5%, and 46.8%, respectively.

[0177] That is, it may be seen that the Fc variant according to an aspect is not only easy to apply as a bispecific antibody, but also has excellent heterodimer formation when applied as the above structure.

Example 8. Evaluation of Anticancer Activity of Fab-Fc×scFv-Fc Bispecific Antibodies Including High-Efficiency Fc Variants

[0178] 8-1. Confirmation of Cancer Cell Death and Inhibition of Cancer Growth

[0179] The anti-PD-L1×anti-CD3 scFv bispecific antibody prepared in Example 7-1 was evaluated for its ability to kill cancer cells and inhibit cancer growth.

[0180] Specifically, 10% (v/v) FBS and 1% (v/v) penicillin-streptomycin was added to RPM11640 medium (#11875-093, Gibco), and breast cancer cells (MDA-MB-231) were cultured at 37° C. under the conditions of 5% C02. After dividing the cells in a 96-well plate at a concentration of 10,000 cells/well, the cells were cultured overnight at 37° C. under the conditions of 5% C02, and human peripheral blood mononuclear cells (PBMC) (effector cells) were co-cultured after being divided at a ratio of 20:1 (effector cells: target (MDA-MB-231) cells). Then, the cells were treated with anti-PD-L1×anti-CD3 scFv bispecific antibodies in the wells, and then cultured for 48 hours. Then, after recovering the supernatant, cytotoxicity was analyzed according to Equation 1 below by using an LDH Cytotoxicity assay kit (#C20301, Invitrogen). Avelumab (anti-PD-L1 antibody, Bavencio®) was used as a positive control group.

[00001]$\begin{array}{cc}\%\mathrm{Cytotoxicity}=\frac{\begin{array}{c}\mathrm{LDH}\mathrm{activity}\mathrm{when}\mathrm{treated}\mathrm{with}\mathrm{compound}-\\ \mathrm{spontaneous}\mathrm{LDH}\mathrm{activity}\end{array}}{\begin{array}{c}\mathrm{maximum}\mathrm{LDH}\mathrm{activity}-\\ \mathrm{spontaneous}\mathrm{LDH}\mathrm{activity}\end{array}}\times 100\%& \left[\mathrm{Equation}1\right]\end{array}$

TABLE-US-00013 TABLE 12 MDA-MB-231 cancer cell growth inhibitory effect (EC.sub.50) Anti-PD-L1 × anti-CD3 scFv BsAb  1.3 ng/mL Avelumab (anti-PD-L1 antibody) 11.8 ng/mL

[0181] FIG. 9 is a graph evaluating the ability of anti-PD-L1×anti-CD3 scFv bispecific antibodies to induce cancer cell death in vitro (Avelumab: positive control group, anti-PD-L1×anti-CD3 scFv BsAb: anti-PD-L1×anti-CD3 scFv bispecific antibody having a PTC074 sequence in the CH3 domain).

[0182] As a result, as shown in FIG. 9, the Emax (maximum cytotoxic effect) of the positive control group was 26% at the maximum concentration of the substance, whereas the Emax of the Fab-Fc×scFv-Fc hetero-bispecific antibody was 76.3%, and the hetero-bispecific antibody was confirmed to have remarkably high cytotoxic effect on cancer cells. In addition, the positive control group showed saturation without further increase of cell lysis at a substance concentration of 21 ng/mL or more, and it was confirmed that an effective amount was formed in the range of 0.sub.log ng/mL to 2% ng/mL. On the other hand, the Fab-Fc×scFv-Fc hetero-bispecific antibody showed saturation without further increase of cell lysis at a substance concentration of 1b ng/mL or more, and it was confirmed that an effective amount was formed in the range of −1.sub.log ng/mL to 1.sub.log ng/mL.

[0183] In addition, as shown in Table 12, in case of the positive control group, inhibitory effect on growth of MDA-MB-231 cancer cells was represented by EC.sub.50 of 11.8 ng/mL, whereas the Fab-Fc×scFc-Fc hetero-bispecific antibody had EC.sub.50 of 1.3 ng/mL, and the hetero-bispecific antibody was confirmed to be more efficient in inhibiting growth of cancer cells.

[0184] That is, the Fab-Fc×scFv-Fc hetero-bispecific antibody formed by the Fc variant according to an aspect shows an excellent anticancer effect at a lower concentration compared to known immunotherapy drugs, and side effects of existing therapeutic agents such as normal cell destruction or resistance may be reduced.

[0185] 8-2. Confirmation of Anticancer Efficacy

[0186] In vivo anticancer efficacy of anti-PD-L1×anti-CD3 scFv bispecific antibody was evaluated by using a humanized mouse xenograft model. Specifically, a mixture of MDA-MB-231 cells (5×10.sup.6) and purified human T cells (2.5×10.sup.6) was mixed with the same amount of Matrigel, and subcutaneously administered to NOD/SCID mice (female, 6 weeks old, Jabio) in the flank at a dose of 0.2 mL/mouse. One hour after inoculation, 2.5 mg/kg of the anti-PD-L1×anti-CD3 scFv bispecific antibody prepared in Example 7-1 was intravenously administered (5 times/week). Avelumab, a positive control, was administered intravenously (3 times/week) at 20 mg/kg. From 7 days after inoculation, tumor volumes were measured (3 times/week) to compare and evaluate anticancer efficacies of the two substances.

[0187] FIG. 10 is a graph evaluating the ability of anti-PD-L1×anti-CD3 scFv bispecific antibodies to inhibit cancer cell growth in vivo (Avelumab: positive control group, anti-PD-L1×anti-CD3 scFv BsAb: anti-PD-L1×anti-CD3 scFv bispecific antibody having a PTC074 sequence in the CH3 domain).

[0188] As a result, as shown in FIG. 10, in case of the negative control group, average tumor volume gradually increased for 28 days until it became 600 mm.sup.3 or more, and it was confirmed that there was no tumor growth inhibitory effect. In addition, in case of the positive control group, tumor volume continued to increase, and it was confirmed that the tumor growth inhibitory effect was 59% on the day 28. On the other hand, in case of Fab-Fc×scFv-Fc, tumor growth inhibition regression was maintained the same from days 9 to 21, and the tumor growth inhibition effect was 80% on day 28, and the bispecific antibody was confirmed to effectively reduce tumor growth in humanized mouse xenograft models.

[0189] That is, the Fab-Fc×scFv-Fc hetero-bispecific antibody formed by the Fc variant according to an aspect has excellent tumor growth inhibitory effect, and thus may be used for prevention or treatment of various cancers, including breast cancer.

[0190] The above description of the present disclosure is for illustrative purposes, and those skilled in the art to which the present disclosure belongs will be able to understand that the examples and embodiments can be easily modified without changing the technical idea or essential features of the disclosure. Therefore, it should be understood that the above examples are not limitative, but illustrative in all aspects.