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1. WO2020191485 - ANTI-EGFRVIII ANTIBODIES AND ANTIGEN-BINDING FRAGMENTS THEREOF

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TITLE: ANTI-EGFRVIII ANTIBODIES AND ANTIGEN-BINDING FRAGMENTS THEREOF

TECHNICAL FIELD

The present disclosure provides antigen-binding agents such as antibodies or antigen binding fragments thereof, chimeric antigen receptors (CARs), bispecific T-cell engagers (BiTEs) and the like that specifically bind to epidermal growth factor receptor variant III (EGFRvlll). The EGFRvlll-specific antibodies or antigen-binding fragments thereof, CARs or BiTEs of the instant disclosure may be used, for example, for the treatment of cancer. Antibody drug conjugates targeting EGFRvlll-expressing cells are particularly contemplated.

BACKGROUND

The epidermal growth factor receptor variant III (EGFRvlll) is amplified, highly expressed and present in 25-64% of glioblastoma multiforme (GBM). It should be noted that the different detection methods yielded inconsistent results, but EGFRvlll mRNA and protein expression has been detected in a subset of carcinomas of the breast as well as in head and neck squamous cell carcinoma (HNSCC) using multiple complementary techniques (reviewed in Gan et al 2013). Unlike wild type (wt) epidermal growth factor receptor (EGFR), which is expressed in tissues of epithelial, mesenchymal and neuronal origin and plays a major role in normal cellular processes such as proliferation, differentiation and development, EGFRvlll is not expressed on normal tissues.

The EGFRvlll variant originates from an in-frame deletion of exons 2-7 of the EGFR gene resulting in the removal of a sequence encoding 267 amino acid residues of the extracellular domain. The newly formed splice junction encodes a glycine residue which has no counterpart in wild type human EGFR and therefore forms a neo-epitope. Moreover, numerous studies showed that normal tissues are devoid of EGFRvlll. EGFRvlll thus contains a new tumor specific cell surface epitope that could be exploited for antibody targeted therapies. However, the EGFRvlll neo-epitope is not very immunogenic compared to the remaining of the human sequence, and many of the antibodies generated to date have not been shown to be specifically recognizing EGFRvlll (reviewed in Gan et al 2013).

In rare cases, monoclonal antibodies (mAbs) directed against the EGFRvlll neo-epitope have been described, including antibody 13.1.2 (US Pat. No. 7,736,644) which is also being developed as an antibody drug conjugate (ADC) by Amgen (AMG 595: Hamblett K.J, et al., Molecular Cancer Therapeutics, Vol. 14(7), pp.1614-24, 2015). US patent No. 9,562,102 also

describes the 806 antibody developed by Abbvie (ABT-806, ABT-414), which binds to EGFRvlll as well as a subset of amplified EGFR on EGFR overexpressing tumor cells (Cleary, JM et al., Invest New Drugs, 33(3), pp. 671-8, 2015; Reilly, EB., Molecular Cancer Therapeutics, Vol. 14(5), pp.1 141 -51 , 2015). Although this antibody has been shown to bind preferentially to tumor EGFR in preclinical models, binding of this antibody to wt EGFR present in human skin has been shown to account for the cutaneous toxicity that ABT-806 exhibits in some patients (Cleary et al 2015).

Antibodies or antigen-binding fragments thereof that specifically target an epitope of EGFRvlll that is absent or not accessible in EGFR-expressing cells would be beneficial for the treatment of cancer patients.

SUMMARY

Antigen-binding agents such as antibodies or an antigen-binding fragments thereof, chimeric antigen receptors (CARs), bispecific T-cell engagers (BiTEs) and the like which specifically bind to epidermal growth factor receptor variant III (EGFRvlll) are provided.

As described in more details below, some anti-EGFRvlll antibodies or antigen-binding fragments thereof may bind to EGFRvlll at the surface of cancer cells (e.g., glioblastoma cells). In some embodiments, the antibodies or antigen-binding fragments thereof do not significantly bind to EGFR expressed on cancer cells (e.g., U87MG-EGFR WT).

The antibodies or antigen-binding fragments thereof of the present disclosure may be internalized by cancer cells and may thus be used, in an aspect thereof, for delivery of cargo molecules. Particularly contemplated are anti-EGFRvlll antibodies or antigen-binding fragments thereof that are conjugated to therapeutic moieties. The anti-EGFRvlll antibodies described herein may be used for inhibiting the growth of EGFRvlll-expressing tumor cells.

In some embodiments of the present disclosure, the anti-EGFRvlll antibodies or antigen binding fragments thereof may be able to bind to an epitope present in both native EGFRvlll (e.g., native recombinant EGFRvlll) and denatured EGFRvlll (e.g., denatured recombinant EGFRvlll).

Generally, the antibodies or antigen-binding fragments thereof of the present disclosure may be able to bind to a peptide comprising an EGFRvlll fragment consisting of amino acid residues 1 to 76 of EGFRvlll (SEQ ID NO:1 19). A subset of the antibodies or antigen-binding fragments thereof are able to bind to amino acid residues 1 to 18 of EGFRvlll (SEQ ID NO:125) and another subset of antibodies are able to bind amino acid residues 15 to 37 of EGFRvlll (SEQ ID NO:6).

More particularly, the present disclosure provides anti-EGFRvlll antibodies or antigen binding fragments thereof that may be able to bind to one or more of the EGFRvlll fragments illustrated in Figures 4a and/or 4b.

Embodiments of anti-EGFRvlll antibodies or antigen-binding fragments thereof encompassed by the present disclosure includes, for example:

Antibodies that are able to bind to a peptide comprising an EGFRvlll fragment consisting of amino acid residues 1 to 18 of EGFRvlll (SEQ ID NO:125); Antibodies that are able to bind to a peptide comprising an EGFRvlll fragment consisting of amino acid residues 3 to 18 of EGFRvlll (SEQ ID NO:129); Antibodies that are able to bind to a peptide comprising an EGFRvlll fragment consisting of amino acid residues 15 to 37 of EGFRvlll (SEQ ID NO:6), or; Antibodies that are able to bind to a peptide comprising an EGFRvlll fragment consisting of amino acid residues 19 to 37 of EGFRvlll (SEQ ID NO:142)

Some particular anti-EFGRvlll antibodies or antigen-binding fragments thereof encompassed by the present disclosure include those that do not require the presence of amino acid residues 1-2 of EGFRvllll for binding. Particularly contemplated are anti-EFGRvlll antibodies or antigen-binding fragments thereof that are capable of binding to one or more EGFRvlll fragments amongst fragment 19-76 (SEQ ID NO:138), fragment 19-62 (SEQ ID NO:139), fragment 19-49 (SEQ ID NO:140), fragment 19-45 (SEQ ID NO:141 ), fragment 28-45 (SEQ ID NO:143), fragment 28-37 (SEQ ID NO:144), fragment 19-37 (SEQ ID NO:142), fragment 3-45 (SEQ ID NO:127), fragment 3-49 (SEQ ID NO:126), fragment 3-37 (SEQ ID NO:128), fragment 6-49 (SEQ ID NO:130), fragment 6-45 (SEQ ID NO:131 ), fragment 6-37 (SEQ ID NO:132), fragment 10-49 (SEQ ID NO:133), fragment 10-45 (SEQ ID NO:134), fragment 10-37 (SEQ ID NO:135), fragment 15-49 (SEQ ID NO:136), fragment 15-45 (SEQ ID NO:137) or fragment 15-37 (SEQ ID NO:6).

The anti-EGFRvlll antibodies or antigen-binding fragments provided herein include antibodies or antigen-binding fragments that are able to bind to a peptide comprising an EGFRvlll fragment consisting of amino acid residues 3 to 37 of EGFRvlll (SEQ ID NO:128) such as for example, the F260-5G6 (referred herein also as 5G6), F263-1A8 (referred herein also as 1A8), F263-4B3 (referred herein also as 4B3), F263-4E1 1 (referred herein also as 4E1 1 ), F263-5D8 (referred herein also as 5D8) and F265-9C9 (referred to herein also as 9C9) antibody.

Other anti-EGFRvlll antibodies or antigen-binding fragments provided herein include antibodies or antigen-binding fragments that are able to bind to a peptide comprising an EGFRvlll fragment consisting of amino acid residues 1 to 33 of EGFRvlll (SEQ ID NO:124).

Exemplary antibodies or antigen-binding fragments thereof of the present disclosure include an antibody or antigen-binding fragment thereof that specifically binds to EGFRvlll (SEQ ID NO:5) and that is capable of binding to an EGFRvlll fragment selected from the group consisting of:

a. a fragment consisting of amino acid residues 15 to 37 of EGFRvlll (SEQ ID NO:6); b. a fragment consisting of amino acid residues 1 to 76 of EGFRvlll (SEQ ID NO:1 19); c. a fragment consisting of amino acid residues 1 to 62 of EGFRvlll (SEQ ID NO: 120); d. a fragment consisting of amino acid residues 1 to 49 of EGFRvlll (SEQ ID NO:121 ); e. a fragment consisting of amino acid residues 1 to 45 of EGFRvlll (SEQ ID NO:122); f. a fragment consisting of amino acid residues 1 to 37 of EGFRvlll (SEQ ID NO:123); g. a fragment consisting of amino acid residues 3 to 49 of EGFRvlll (SEQ ID NO:126); h. a fragment consisting of amino acid residues 3 to 45 of EGFRvlll (SEQ ID NO:127); i. a fragment consisting of amino acid residues 3 to 37 of EGFRvlll (SEQ ID NO:128); j. a fragment consisting of amino acid residues 6 to 49 of EGFRvlll (SEQ ID NO:130); k. a fragment consisting of amino acid residues 6 to 45 of EGFRvlll (SEQ ID NO:131 );

L. a fragment consisting of amino acid residues 6 to 37 of EGFRvlll (SEQ ID NO:132); m. a fragment consisting of amino acid residues 10 to 49 of EGFRvlll (SEQ ID NO:133); n. a fragment consisting of amino acid residues 10 to 45 of EGFRvlll (SEQ ID NO:134); o. a fragment consisting of amino acid residues 10 to 37 of EGFRvlll (SEQ ID NO:135); p. a fragment consisting of amino acid residues 15 to 49 of EGFRvlll (SEQ ID NO:136); q. A fragment consisting of amino acid residues 15 to 45 of EGFRvlll (SEQ ID NO:137); r. a fragment consisting of amino acid residues 19 to 76 of EGFRvlll (SEQ ID NO:138); s. a fragment consisting of amino acid residues 19 to 62 of EGFRvlll (SEQ ID NO:139); t. a fragment consisting of amino acid residues 19 to 49 of EGFRvlll (SEQ ID NO:140); u. a fragment consisting of amino acid residues 19 to 45 of EGFRvlll (SEQ ID NO:141 ); v. a fragment consisting of amino acid residues 19 to 37 of EGFRvlll (SEQ ID NO:142), and;

w. any combination of the above fragments thereof,

wherein the antibody or antigen binding fragment thereof fails to bind a peptide comprising or consisting of the amino acid sequence set forth in SEQ ID NO: 149.

The antibody or antigen-binding fragment thereof of the present disclosure may be capable of binding to a peptide comprising or consisting of an amino acid sequence selected from the group consisting of SEQ ID NO:145, SEQ ID NO:146, SEQ ID NO:147, SEQ ID NO:148, SEQ ID NO:150, SEQ ID NO:151 , SEQ ID NO:152, SEQ ID NO:153, SEQ ID NO:155, SEQ ID NO:156, SEQ ID NO:157, SEQ ID NO:162, SEQ ID NO:164, SEQ ID NO:165 and combination thereof.

The antibody or antigen-binding fragment thereof may also be capable of binding to a peptide comprising or consisting of an amino acid sequence set forth in SEQ ID NO:160.

Other exemplary embodiments of the disclosure include antibodies or antigen-binding fragments thereof that specifically bind to EGFRvlll (SEQ ID NO:5) and that are capable of binding to an EGFRvlll fragment selected from the group consisting of:

a. a fragment consisting of amino acid residues 15 to 37 of EGFRvlll (SEQ ID NO:6); b. a fragment consisting of amino acid residues 1 to 76 of EGFRvlll (SEQ ID NO:1 19); c. a fragment consisting of amino acid residues 1 to 49 of EGFRvlll (SEQ ID NO:121 ); d. a fragment consisting of amino acid residues 1 to 37 of EGFRvlll (SEQ ID NO:123); e. a fragment consisting of amino acid residues 3 to 37 of EGFRvlll (SEQ ID NO:128); and;

f. any combination of the above fragments thereof,

wherein the antibodies or antigen binding fragments thereof fail to bind a peptide comprising of consisting of the amino acid sequence set forth in SEQ ID NO: 149.

The antibody or antigen-binding fragment thereof of the present disclosure may be capable of binding to a peptide comprising or consisting of an amino acid sequence selected from the group consisting of SEQ ID NO:145, SEQ ID NO:146, SEQ ID NO:147, SEQ ID NO:151 , SEQ ID NO:152, SEQ ID NO:153, SEQ ID NO:155, SEQ ID NO:156, SEQ ID NO:157, SEQ ID NO:158, SEQ ID NO:160, SEQ ID NO:161 , SEQ ID NO:162, SEQ ID NO:164, SEQ ID NO:165 and combination thereof. The antibody or antigen-binding fragment thereof may also be capable of binding to a peptide comprising or consisting of an amino acid sequence set forth in SEQ ID NO:154. The antibody or antigen-binding fragment thereof may also be capable of binding to a peptide comprising or consisting of an amino acid sequence set forth in SEQ ID NO:159.

Yet other exemplary embodiments of the disclosure include antibodies or antigen-binding fragments thereof that specifically bind to EGFRvlll (SEQ ID NO:5) and that are capable of binding to an EGFRvlll fragment selected from the group consisting of:

a. a fragment consisting of amino acid residues 15 to 37 of EGFRvlll (SEQ ID NO:6); b. a fragment consisting of amino acid residues 1 to 76 of EGFRvlll (SEQ ID NO:1 19);

c. a fragment consisting of amino acid residues 1 to 62 of EGFRvlll (SEQ ID NO: 120); d. a fragment consisting of amino acid residues 1 to 49 of EGFRvlll (SEQ ID NO:121 ); e. a fragment consisting of amino acid residues 1 to 45 of EGFRvlll (SEQ ID NO:122); f. a fragment consisting of amino acid residues 1 to 37 of EGFRvlll (SEQ ID NO:123); g. a fragment consisting of amino acid residues 3 to 49 of EGFRvlll (SEQ ID NO:126); h. a fragment consisting of amino acid residues 3 to 45 of EGFRvlll (SEQ ID NO:127); i. a fragment consisting of amino acid residues 3 to 37 of EGFRvlll (SEQ ID NO:128); j. a fragment consisting of amino acid residues 6 to 49 of EGFRvlll (SEQ ID NO:130); k. a fragment consisting of amino acid residues 6 to 45 of EGFRvlll (SEQ ID NO:131 );

L. a fragment consisting of amino acid residues 6 to 37 of EGFRvlll (SEQ ID NO:132); m. a fragment consisting of amino acid residues 10 to 49 of EGFRvlll (SEQ ID NO:133); n. a fragment consisting of amino acid residues 10 to 45 of EGFRvlll (SEQ ID NO:134); o. a fragment consisting of amino acid residues 10 to 37 of EGFRvlll (SEQ ID NO:135); p. a fragment consisting of amino acid residues 15 to 49 of EGFRvlll (SEQ ID NO:136); q. a fragment consisting of amino acid residues 15 to 45 of EGFRvlll (SEQ ID NO:137); and;

r. any combination of the above fragments thereof.

The antibodies or antigen-binding fragments thereof may also bind to:

a. a fragment consisting of amino acid residues 19 to 49 of EGFRvlll (SEQ ID NO:140); b. a fragment consisting of amino acid residues 19 to 37 of EGFRvlll (SEQ ID NO:142); c. a fragment consisting of amino acid residues 28 to 45 of EGFRvlll (SEQ ID NO:143); d. a fragment consisting of amino acid residues 28 to 37 of EGFRvlll (SEQ ID NO:144), or;

any combination of the above fragments thereof.

The antibody or antigen-binding fragment thereof may also be capable of binding to a peptide comprising or consisting of an amino acid sequence selected from the group consisting SEQ ID NO:145, SEQ ID NO:147, SEQ ID NO:148, SEQ ID NO:150, SEQ ID NO:151 , SEQ ID NO:152, SEQ ID NO:153, SEQ ID NO:155, SEQ ID NO:156, SEQ ID NO:157, SEQ ID NO:165 and combination thereof. The antibody or antigen-binding fragment thereof may also be capable of binding to a peptide comprising or consisting of an amino acid sequence set forth in SEQ ID NO:149.

Also provided are anti-EGFRvlll antibodies or antigen-binding fragments thereof that are able to bind an epitope comprising or involving amino acid residue Cys20 in said peptide. These include for example, anti-EGFRvlll antibodies or antigen-binding fragments that bind EGFRvlll and/or a peptide comprising an EGFRvlll fragment consisting of the amino acid sequence set forth in SEQ ID NO:6 but that are not able to bind a peptide comprising or consisting of the amino acid sequence SCVRAAGADSYEMEEDGVRKCKK (SEQ ID NO:149). Such antibodies or antigen binding fragments encompass, for example, the 4B3, 5D8 and 4E1 1 antibodies.

Also specifically encompassed by the present disclosure are anti-EGFRvlll antibodies or antigen-binding fragments thereof that are able to bind an epitope comprising or involving amino acid residue Cys35 in said peptide. These include for example, anti-EGFRvlll antibodies or antigen-binding fragments that bind EGFRvlll and/or a peptide comprising an EGFRvlll fragment consisting of the amino acid sequence set forth in SEQ ID NO:6 but that are not able to bind a peptide comprising or consisting of the amino acid sequence SCVRACGADSYEMEEDGVRKAKK (SEQ ID NO:163). Such antibodies or antigen binding fragments encompass, for example, the 4B3, 5D8, 9C9 and 4E1 1 antibodies.

Further encompassed by the present disclosure are anti-EGFRvlll antibodies or antigen binding fragments thereof that are able to bind an epitope in a peptide comprising or involving amino acid residue Cys20 and Cys35 in said peptide. These include for example, anti-EGFRvlll antibodies or antigen-binding fragments that bind EGFRvlll and/or a peptide comprising or consisting of an EGFRvlll fragment set forth in SEQ ID NO:6 but that are not able to bind a peptide comprising or consisting of the amino acid sequence selected from SCVRAAGADSYEMEEDGVRKCKK (SEQ ID NO:149) or SCVRACGADSYEMEEDGVRKAKK (SEQ ID NO:163). Such antibodies or antigen binding fragments encompass, for example, the 4B3, 5D8 and 4E1 1 antibodies.

In addition to amino acid residues Cys20 and/or Cys35, the epitope to which the anti-EGFRvlll antibodies or antigen-binding fragments thereof bind or which are involved in its binding may further include Glu26, Asp30, Gly31 and/or Arg33. The epitope may also further include Asp23 and/or Val32.

For example, anti-EGFRvlll antibodies or antigen-binding fragments thereof encompassed by the present disclosure include those that bind to an epitope comprising or involving:

Cys20, Glu26, Asp30, Gly31 , Arg33 and Cys35, or;

Cys20, Asp23, Glu26, Asp30, Gly31 , Val32, Arg33 and Cys35.

In addition to amino acid residues Cys20 and/or Cys35, the epitope to which the anti-EGFRvlll antibodies or antigen-binding fragments thereof bind or involved in its binding may further include Arg18 and/or Gly21. The epitope may also further include Glu26 and/or Gly31.

For example, the anti-EGFRvlll antibodies or antigen-binding fragments thereof encompassed by the present disclosure include those that bind to an epitope comprising or involving:

- Arg18, Cys20, Gly21 and Cys35, or;

- Arg18, Cys20, Gly21 , Glu26, Gly31 and Cys35.

Additional anti-EGFRvlll antibodies or antigen-binding fragments thereof encompassed by the present disclosure include those that bind to an epitope comprising or involving:

Cys16, Glu26, Gly31 , Val32, Arg33, Lys34, Cys35 and Lys36, or;

Cys16, Cys20, Glu26, Asp30, Gly31 , Val32, Arg33, Lys34, Cys35 and Lys36.

Embodiments of the disclosure particularly include anti-EGFRvlll antibodies or antigen binding fragments thereof that are able to compete with the 4E11 antibody or antigen-binding fragment thereof or that are able to compete with an antibody or antigen-binding fragment thereof that comprises the CDRs of the 4E11 antibody.

Other embodiments of the present disclosure include anti-EGFRvlll antibodies or antigen binding fragments thereof that are able to compete with the 5G6 antibody or antigen-binding fragment thereof or that are able to compete with an antibody or antigen-binding fragment thereof that comprises the CDRs of the 5G6 antibody.

Further embodiments of the present disclosure include anti-EGFRvlll antibodies or antigen-binding fragments thereof that are able to compete with the 9C9 antibody or antigen binding fragment thereof or that are able to compete with an antibody or antigen-binding fragment thereof that comprises the CDRs of the 9C9 antibody.

A particular embodiment encompassed by the present disclosure relates to an anti- EGFRvlll antibody or antigen-binding fragment thereof comprising the CDRs of the 4E11 antibody.

The present disclosure provides anti-EGFRvlll antibodies or antigen binding fragments comprising a sequence selected from the group consisting of:

- an antibody or fragment thereof comprising CDRL1 (SEQ ID NO:38), CDRL2 (SEQ ID NO:39), CDRL3 (SEQ ID NO:40), CDRH1 (SEQ ID NO:43), CDRH2 (SEQ ID NO:44) and CDRH3 (SEQ ID NO:45) of the 4E1 1 antibody;

- an antibody or fragment thereof comprising CDRL1 (SEQ ID NO:8), CDRL2 (SEQ ID NO:9), CDR L3 (SEQ ID NO:10), CDRH1 (SEQ ID NO:13), CDRH2 (SEQ ID NO:14) and CDRH3 (SEQ ID NO:15) of the 5G6 antibody;

- an antibody or fragment thereof comprising CDRL1 (SEQ ID NO:18), CDRL2 (SEQ ID NO:19), CDRL3 (SEQ ID NO:20), CDRH1 (SEQ ID NO:23), CDRH2 (SEQ ID NO:24) and CDRH3 (SEQ ID NO:25) of the 1A8 antibody;

- an antibody or fragment thereof comprising CDRL1 (SEQ ID NO:28), CDRL2 (SEQ ID NO:29), CDRL3 (SEQ ID NO:30), CDRH1 (SEQ ID NO:33), CDRH2 (SEQ ID NO: 34) and CDRH3 (SEQ ID NO:35) of the 4B3 antibody;

- an antibody or fragment thereof comprising CDRL1 (SEQ ID NO:48), CDRL2 (SEQ ID NO:49), CDRL3 (SEQ ID NO:50), CDRH1 (SEQ ID NO:53), CDRH2 (SEQ ID NO:54) and CDRH3 (SEQ ID NO:55) of the 5D8 antibody;

- an antibody or fragment thereof comprising CDRL1 (SEQ ID NO:58), CDRL2 (SEQ ID NO:59), CDRL3 (SEQ ID NO:60), CDRH1 (SEQ ID NO:63), CDRH2 (SEQ ID NO:64), CDRH3 (SEQ ID NO:65) of the 9C9 antibody; and

- an antibody orfragment thereof comprising CDRL1 (SEQ ID NO: 68 or 73), CDRL2 (SEQ ID NO:69 or 74), CDRL3 (SEQ ID NO:70 or 75), CDRH1 (SEQ ID NO:78), CDRH2 (SEQ ID NO:79) and CDRH3 (SEQ ID NO:80) of the F266-1 1 B1 (referred to herein as 1 1 B1 ), F266-1 1 C8 (referred to herein as 1 1 C8), F266-1 1 H5 (referred to herein as 1 1 H5) and/or F266-1 1 H3 (referred to herein as 1 1 H3) antibodies.

Embodiments encompassed by the present disclosure relates to an anti-EGFRvlll antibody or antigen-binding fragment thereof comprising the CDRs of the 5G6 antibody,

Another embodiment encompassed by the present disclosure relates to an anti-EGFRvlll antibody or antigen-binding fragment thereof comprising the CDRs of the 1A8 antibody.

A further embodiment encompassed by the present disclosure relates to an anti-EGFRvlll antibody or antigen-binding fragment thereof comprising the CDRs of the 4B3 antibody.

Another embodiment encompassed by the present disclosure relates to an anti-EGFRvlll antibody or antigen-binding fragment thereof comprising the CDRs of the 5D8 antibody.

A further embodiment encompassed by the present disclosure relates to an anti-EGFRvlll antibody or antigen-binding fragment thereof comprising the CDRs of the 9C9 antibody.

Another embodiment encompassed by the present disclosure relates to an anti-EGFRvlll antibody or antigen-binding fragment thereof comprising the CDRs of the 11 B1 or of the 1 1C8 antibody.

The present disclosure provides anti-EGFRvlll antibodies or antigen-binding fragments selected from the group consisting of:

an antibody or antigen-binding fragment thereof comprising CDR sequences consisting of CDRL1 (SEQ ID NO:8), CDRL2 (SEQ ID NO:9), CDRL3 (SEQ ID NO:10), CDRH1 (SEQ ID NO:13), CDRH2 (SEQ ID NO:14), CDRH3 (SEQ ID NO:15);

an antibody or antigen-binding fragment thereof comprising CDR sequences consisting of CDRL1 (SEQ ID NO:18), CDRL2 (SEQ ID NO:19), CDRL3 (SEQ ID NO:20), CDRH1 (SEQ ID NO:23), CDRH2 (SEQ ID NO:24), CDRH3 (SEQ ID NO:25); an antibody or antigen-binding fragment thereof comprising CDR sequences consisting of CDRL1 (SEQ ID NO:28), CDRL2 (SEQ ID NO:29), CDRL3 (SEQ ID NO:30), CDRH1 (SEQ ID NO:33), CDRH2 (SEQ ID NO:34), CDRH3 (SEQ ID NO:35); an antibody or antigen-binding fragment thereof comprising CDR sequences consisting of CDRL1 (SEQ ID NO:38), CDRL2 (SEQ ID NO:39), CDRL3 (SEQ ID NO:40), CDRH1 (SEQ ID NO:43), CDRH2 (SEQ ID NO:44), CDRH3 (SEQ ID NO:45); an antibody or antigen-binding fragment thereof comprising CDR sequences consisting of CDRL1 (SEQ ID NO:48), CDRL2 (SEQ ID NO:49), CDRL3 (SEQ ID NO:50), CDRH1 (SEQ ID NO:53), CDRH2 (SEQ ID NO:54), CDRH3 (SEQ ID NO:55); an antibody or antigen-binding fragment thereof comprising CDR sequences consisting of CDRL1 (SEQ ID NO:58), CDRL2 (SEQ ID NO:59), CDRL3 (SEQ ID NO:60), CDRH1 (SEQ ID NO:63), CDRH2 (SEQ ID NO:64), CDRH3 (SEQ ID NO:65); an antibody or fragment thereof comprising CDR sequences consisting of CDRL1 (SEQ ID NO:68), CDRL2 (SEQ ID NO:69), CDRL3 (SEQ ID NO:70), CDRH1 (SEQ ID NO:78), CDRH2 (SEQ ID NO:79), CDRH3 (SEQ ID NO:80), and;

an antibody or antigen-binding fragment thereof comprising CDR sequences consisting of CDRL1 (SEQ ID NO:73), CDRL2 (SEQ ID NO:74), CDRL3 (SEQ ID NO:75), CDRH1 (SEQ ID NO:78), CDRH2 (SEQ ID NO:79), CDRH3 (SEQ ID NQ:80).

The present disclosure provides in some embodiments, an antigen-binding agent such as an antibody or an antigen-binding fragment thereof, CAR, BiTE and the like which specifically binds to EGFRvlll and which may comprise for example:

a. a light chain variable region which may comprise a CDRL1 having the amino acid sequence set forth in SEQ ID NO:8, a CDRL2 having the amino acid sequence set forth in SEQ ID NO:9 and a CDRL3 having the amino acid sequence set forth in SEQ ID NO:10 and a heavy chain variable region which may comprise a CDRH1 having the amino acid sequence set forth in SEQ ID NO:13, a CDRH2 having the amino acid sequence set forth in SEQ ID NO:14 and a CDRH3 having the amino acid sequence set forth in SEQ ID NO:15;

b. a light chain variable region which may comprise a CDRL1 having the amino acid sequence set forth in SEQ ID NO:18, a CDRL2 having the amino acid sequence set forth in SEQ ID NO:19 and a CDRL3 having the amino acid sequence set forth in SEQ ID NO:20 and a heavy chain variable region which may comprise a CDRH1 having the amino acid sequence set forth in SEQ ID NO:23, a CDRH2 having the amino acid sequence set forth in SEQ ID NO:24 and a CDRH3 having the amino acid sequence set forth in SEQ ID NO:25;

c. a light chain variable region which may comprise a CDRL1 having the amino acid sequence set forth in SEQ ID NO:28, a CDRL2 having the amino acid sequence set forth in SEQ ID NO:29 and a CDRL3 having the amino acid sequence set forth in SEQ ID NO:30 and a heavy chain variable region which may comprise a CDRH1 having the amino acid sequence set forth in SEQ ID NO:33, a CDRH2 having the amino acid sequence set forth in SEQ ID NO:34 and a CDRH3 having the amino acid sequence set forth in SEQ ID NO:35;

d. a light chain variable region which may comprise a CDRL1 having the amino acid sequence set forth in SEQ ID NO:38, a CDRL2 having the amino acid sequence set forth in SEQ ID NO:39 and a CDRL3 having the amino acid sequence set forth in SEQ ID NO:40 and a heavy chain variable region which may comprise a CDRH1 having the amino acid sequence set forth in SEQ ID NO:43, a CDRH2 having the amino acid sequence set forth in SEQ ID NO:44 and a CDRH3 having the amino acid sequence set forth in SEQ ID NO:45;

e. a light chain variable region which may comprise a CDRL1 having the amino acid sequence set forth in SEQ ID NO:48, a CDRL2 having the amino acid sequence

set forth in SEQ ID NO:49 and a CDRL3 having the amino acid sequence set forth in SEQ ID NO:50 and a heavy chain variable region which may comprise a CDRH1 having the amino acid sequence set forth in SEQ ID NO:53, a CDRH2 having the amino acid sequence set forth in SEQ ID NO:54 and a CDRH3 having the amino acid sequence set forth in SEQ ID NO:55;

f. a light chain variable region which may comprise a CDRL1 having the amino acid sequence set forth in SEQ ID NO:58, a CDRL2 having the amino acid sequence set forth in SEQ ID NO:59 and a CDRL3 having the amino acid sequence set forth in SEQ ID NO:60 and a heavy chain variable region which may comprise a CDRH1 having the amino acid sequence set forth in SEQ ID NO:63, a CDRH2 having the amino acid sequence set forth in SEQ ID NO:64 and a CDRH3 having the amino acid sequence set forth in SEQ ID NO:65;

g. a light chain variable region which may comprise a CDRL1 having the amino acid sequence set forth in SEQ ID NO:68, a CDRL2 having the amino acid sequence set forth in SEQ ID NO:69 and a CDRL3 having the amino acid sequence set forth in SEQ ID NO:70 and a heavy chain variable region which may comprise a CDRH1 having the amino acid sequence set forth in SEQ ID NO:78, a CDRH2 having the amino acid sequence set forth in SEQ ID NO:79 and a CDRH3 having the amino acid sequence set forth in SEQ ID NO:80, or;

h. a light chain variable region which may comprise a CDRL1 having the amino acid sequence set forth in SEQ ID NO:73, a CDRL2 having the amino acid sequence set forth in SEQ ID NO:74 and a CDRL3 having the amino acid sequence set forth in SEQ ID NO:75 and a heavy chain variable region which may comprise a CDRH1 having the amino acid sequence set forth in SEQ ID NO:78, a CDRH2 having the amino acid sequence set forth in SEQ ID NO:79 and a CDRH3 having the amino acid sequence set forth in SEQ ID NO:80.

The present disclosure provides in additional embodiments, an antigen-binding agent such as an antibody or an antigen-binding fragment thereof, CAR, BiTE and the like which specifically binds to EGFRvlll which may comprise:

a. A light chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO: 1 18 or substantially identical to SEQ ID NO:118 and/or a heavy chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:1 16 or substantially identical to SEQ ID NO:1 16;

b. A light chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO: 1 15 or substantially identical to SEQ ID NO:1 15 and a heavy chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:1 16 or substantially identical to SEQ ID NO:1 16, or;

c. A light chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO: 1 18 or substantially identical to SEQ ID NO:1 18 and a heavy chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:62 or substantially identical to SEQ ID NO:62.

In an aspect thereof, antigen-binding agents having light chain at least 80% identical or substantially identical to the amino acid sequence set forth in SEQ ID NO: 1 15 or SEQ ID NO: 1 18 may have CDRs identical to those of SEQ ID NO: 1 15 or SEQ ID NO: 1 18 respectively.

In an aspect thereof, antigen-binding agents having heavy chain at least 80% identical or substantially identical to the amino acid sequence set forth in SEQ ID NO: 62 or SEQ ID NO: 1 16 may have CDRs identical to those of SEQ ID NO: 62 or SEQ ID NO: 1 16 respectively.

The present disclosure provides in further embodiments, an antigen-binding agent such as an antibody or an antigen-binding fragment thereof, CAR, BiTE and the like which specifically binds to EGFRvlll which may comprise:

a. A light chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:7 or substantially identical to SEQ ID NO:7 and a heavy chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:12 or substantially identical to SEQ ID NO:12; b. A light chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO: 17 or substantially identical to SEQ ID NO:17 and a heavy chain variable region which

may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:22 or substantially identical to SEQ ID NO:22; c. A light chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:27 or substantially identical to SEQ ID NO:27 and a heavy chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:32 or substantially identical to SEQ ID NO:32; d. A light chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO: 37 or substantially identical to SEQ ID NO:37 and a heavy chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:42 or substantially identical to SEQ ID NO:42; e. A light chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:47 or substantially identical to SEQ ID NO:47 and a heavy chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:52 or substantially identical to SEQ ID NO:52; f. A light chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:57 or substantially identical to SEQ ID NO:57 and a heavy chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:62 or substantially identical to SEQ ID NO:62; g. A light chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:67 or substantially identical to SEQ ID NO:67 and a heavy chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:77 or substantially identical to SEQ ID NO: 77, at least 80% identical to the amino acid set forth in SEQ ID NO:92 or substantially identical to SEQ ID NO:92 or at least 80% identical to the amino acid sequence set forth in SEQ ID NO:102 or substantially identical to SEQ ID NO:102, or;

h. A light chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:72 or

substantially identical to SEQ ID NO: 72 and a heavy chain variable region which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:77 or substantially identical to SEQ ID NO: 77 or at least 80% identical to the amino acid set forth in SEQ ID NO:92 or substantially identical to SEQ ID NO:92.

The light chain variable regions, light chains, heavy chain variable regions or heavy chains which may comprise an amino acid sequence at least 80% identical to that of given antibody may have CDRs that are identical to that antibody. In an embodiment of the present disclosure, the VL and VH sequences of the antibodies and antigen-binding fragments provided in the present disclosure may comprise a sequence substantially identical to the VL and VH sequences provided herein, or may comprise a sequence having at least 80%, at least 90%, or at least 95% sequence identity, wherein sequence variation is preferably outside the CDRs of the VL and VH sequences provided.

Moreover, the present disclosure specifically provides antigen-binding agent such as an antibody or an antigen-binding fragment thereof, CAR, BiTE and the like which specifically binds to EGFRvlll and which may comprise:

a. A light chain which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:108 or substantially identical to SEQ ID NO:108 and a heavy chain which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:107 or substantially identical to SEQ ID NO:107, or;

b. A light chain which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:1 10 or substantially identical to SEQ ID NO:1 10 and a heavy chain which may comprise an amino acid sequence at least 80% identical to the amino acid sequence set forth in SEQ ID NO:109 or substantially identical to SEQ ID NO:109.

The present disclosure particularly provides antigen-binding agent such as anti-EGFRvlll antibodies or an antigen-binding fragments thereof, CARs, BiTEs and the like which may comprise:

a. a CDRL1 having the amino acid sequence set forth in SEQ ID NO:38, a CDRL2 having the amino acid sequence set forth in SEQ ID NO:39 and a CDRL3 having the amino acid sequence set forth in SEQ ID NQ:40, a CDRH1 having the amino

acid sequence set forth in SEQ ID NO:43, a CDRH2 having the amino acid sequence set forth in SEQ ID NO:44 and a CDRH3 having the amino acid sequence set forth in SEQ ID NO:45;

b. A light chain variable region which may comprise an amino acid sequence at least 80% identical, at least 85% identical, at least 90% identical, at least 95% identical or identical to the amino acid sequence set forth in SEQ ID NO: 37 and a heavy chain variable region which may comprise an amino acid sequence at least 80% identical, at least 85% identical, at least 90% identical, at least 95% identical or identical to the amino acid sequence set forth in SEQ ID NO:42 or; c. A light chain which may comprise an amino acid sequence at least 80% identical, at least 85% identical, at least 90% identical, at least 95% identical or identical to the amino acid sequence set forth in SEQ ID NO:108 and a heavy chain which may comprise an amino acid sequence at least 80% identical, at least 85% identical, at least 90% identical, at least 95% identical or identical to the amino acid sequence set forth in SEQ ID NO:107.

In accordance with the present disclosure, the antibody or antigen-binding fragment thereof of item b. or c. may have CDRs identical or substantially identical to those set forth in SEQ ID NOs:38, 39, 40, 43, 44 and 45.

In accordance with the present disclosure, the antibody or antigen-binding fragment thereof may have, for example, an affinity of less than 100 nM such as for example, an affinity of 50 nM or less, 20 nM or less, 10 nM or less, 5 nM or less, etc.

Exemplary embodiments of the present disclosure include antibodies or antigen-binding fragments thereof which may comprise a human IgG constant region. Antibodies or antigen binding fragments of the present disclosure may comprise, for example and without limitation, a human lgG1 constant region or a human lgG2 constant region.

In an exemplary embodiment, the antigen-binding agents disclosed herein may comprise humanized framework regions.

In accordance with the present disclosure, the antibody or antigen-binding fragment thereof may be monoclonal antibody, a polyclonal antibody, a humanized antibody, a chimeric antibody, a human antibody, a single chain antibody, or a multispecific antibody (e.g., a bispecific antibody).

Bispecific antibodies or antigen-binding fragments thereof of the present disclosure includes those that may comprise a first arm that specifically binds to a first human EGFRvlll epitope and a second arm that specifically binds to a second (non-overlapping) human EGFRvlll epitope (e.g. a biparatopic antibody).

Additional embodiments of bispecific antibodies or antigen-binding fragments thereof of the present disclosure includes those that may comprise a first arm that specifically binds to a first human EGFRvlll epitope and a second arm that specifically binds to another antigen.

The bispecific antibody or antigen-binding fragment thereof of the present disclosure include bispecific immune cell engagers such as those comprising a first arm that specifically binds to human EGFRvlll and a second arm that specifically binds to CD3.

In accordance with the present disclosure, the antigen-binding fragment comprises, for example, a scFv, a Fab, a Fab' or a (Fab')2.

In a further aspect, the present disclosure provides anti-EGFRvlll antibodies or antigen binding fragments thereof which may be linked to a cargo molecule.

In accordance with the present disclosure, the cargo molecule may comprise a therapeutic moiety, such as for example, a cytotoxic agent, a cytostatic agent, an anti-cancer agent or a radiotherapeutic. In particular embodiments of the disclosure, the antibody drug conjugates may comprise a cytotoxic agent. Another particular embodiment of the disclosure relates to antibody drug conjugates comprising a radiotherapeutic.

In accordance with the present disclosure, the cargo molecule may comprise a detectable moiety.

The antibodies or antigen-binding fragments thereof of the present disclosure may be provided in the form of pharmaceutical compositions. The pharmaceutical composition may comprise, for example, a pharmaceutically acceptable carrier, diluent or excipient.

The present disclosure additionally provides nucleic acid molecules encoding a light chain variable region and/or a heavy chain variable region of the antibody or antigen-binding fragment thereof disclosed herein.

Exemplary embodiments of nucleic acid molecules of the present disclosure include: a. a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO: 1 1 and/or a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence

set forth in SEQ ID NO:16 or that encodes an amino acid sequence substantially identical to the amino acid sequence of SEQ ID NO: 7 and/or SEQ ID NO: 12; b. a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:21 and/or a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:26 or that encodes an amino acid sequence substantially identical to the amino acid sequence of SEQ ID NO:17 and/or SEQ ID NO:22; c. a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:31 and/or a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:36 or that encodes an amino acid sequence substantially identical to the amino acid sequence of SEQ ID NO:27 and/or SEQ ID NO:32 d. a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:41 and/or a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:46 or that encodes an amino acid sequence substantially identical to the sequence of SEQ ID NO:37 and/or SEQ ID NO:42;

e. a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:51 and/or a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:56 or that encodes an amino acid sequence substantially identical to the sequence of SEQ ID NO:47 and/or SEQ ID NO:52;

f. a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:61 and/or a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:66 or that encodes an amino acid sequence substantially identical to the sequence of SEQ ID NO:57 and/or SEQ ID NO:62;

g. a nucleic acid molecule which may comprise the nucleotide sequence a sequence at least 80% identical to set forth in SEQ ID NO:71 and/or a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:81 or that encodes an amino acid sequence substantially identical to the sequence of SEQ ID NO:67 and/or SEQ ID NO:77;

h. a nucleic acid molecule which may comprise the nucleotide sequence a sequence at least 80% identical to set forth in SEQ ID NO:76 and/or a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:81 or that encodes an amino acid sequence substantially identical to the sequence of SEQ ID NO:72 and/or SEQ ID NO:77; i. a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:86 and/or a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:96 or that encodes an amino acid sequence substantially identical to the sequence of SEQ ID NO:82 and/or SEQ ID NO:92; j. a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:91 and/or a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:96 or that encodes an amino acid sequence substantially identical to the sequence of SEQ ID NO:87 and/or SEQ ID NO:92, or;

k. a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:101 and/or a nucleic acid molecule which may comprise a sequence at least 80% identical to the nucleotide sequence set forth in SEQ ID NO:106 or that encodes an amino acid sequence substantially identical to the sequence of SEQ ID NO:97 and/or SEQ ID NO:102.

In a further aspect, the present disclosure provides a kit comprising at least one of the antibody or antigen-binding fragments thereof disclosed herein.

Additional aspects of the present disclosure relate to a vector or set of vectors which may comprise a nucleic acid encoding a light chain variable region and a heavy chain variable region of the antibody or antigen-binding fragment disclosed herein. The nucleic acids encoding the light chain variable region or the light chain and the heavy chain variable region or the heavy chain may be provided on the same vector or on separate vectors.

Further aspects of the present disclosure relate to isolated cells comprising the vector or set of vectors described herein. The isolated cells may be capable of expressing, assembling and/or secreting the antibody or antigen-binding fragment thereof.

Other aspects of the present disclosure relate to a kit comprising a first vial comprising a nucleic acid or vector encoding the light chain of the antibody or antigen-binding fragment thereof of the present disclosure and a second vial comprising a nucleic acid or vector encoding the heavy chain of the antibody or antigen-binding fragment thereof.

Additional aspects of the present disclosure relate to a method of treating cancer which comprises cells (e.g., tumor cells) expressing EGFRvlll. The method may comprise administering the antibody or antigen-binding fragment thereof described herein to subject in need. Antibody or antigen-binding fragments that are conjugated to a therapeutic moiety (ADCs) are particularly contemplated in methods of treatments.

The present disclosure additionally relates to the use of the antibody or antigen-binding fragment thereof described herein in the treatment of cancer.

The present disclosure further relates to the use of the antibody or antigen-binding fragment thereof described herein in the manufacture of a medicament for the treatment of cancer.

In accordance with the present disclosure, the antibody or antigen-binding fragment thereof may be used in combination with a chemotherapeutic.

In accordance with the present disclosure, the subject in need has or is suspected of having gliobastoma multiforme.

Further in accordance with the present disclosure, the subject in need has or is suspected of having a carcinoma.

Further aspects of the present disclosure relate to a method of detecting EGFRvlll. The method may comprise contacting a sample comprising or suspected of comprising EGFRvlll with the antibody or antigen-binding fragment described herein.

Additional aspects of the present disclosure relate to a method of making the antibody or antigen-binding fragment thereof of the present disclosure by culturing a cell comprising nucleic acids or vectors encoding the antibody or antigen-binding fragment so that the antibody or antigen-binding fragment thereof is produced. The antibody or antigen-binding fragment thereof may thus be isolated and/or purified.

The method may further comprise conjugating the antibody or antigen-binding fragment thereof with a cargo molecule, such as for example, a therapeutic moiety.

Further scope, applicability and advantages of the present disclosure will become apparent from the non-restrictive detailed description given hereinafter. It should be understood, however, that this detailed description, while indicating exemplary embodiments of the disclosure, is given by way of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figures 1A-1 K represent histograms obtained using flow cytometry on supernatants of selected hybridomas on U87MG cell lines overexpressing wild type human EGFR (U87WT) or EGFRvlll (U87vlll) as indicated.

Figures 2A-2D represent dose-response binding curves obtained from flow cytometry data of purified monoclonal antibodies on U87MG glioblastoma cell lines overexpressing EGFR vlll (U87MG EGFR vlll) or wild type EGFR (U87MG EGFR wt) as indicated.

Figure 3 is an alignment between the amino acid sequence of the extracellular domains of wild type human EGFR and EGFRvlll. Identical amino acids are underlined.

Figures 4A and 4B show the results of anti-hEGFRvlll mAbs binding properties to various fragments of the EGFRvlll displayed on yeast cells (+++ represents 95% +/- 5% positive yeast cells which is characterized by positive antibody binding with high affinity; ++ represents 70% +/-20% positive yeast cells which is characterized by positive antibody binding with medium affinity; + represents 30% +/- 20% positive yeast cells which is characterized by positive antibody binding with low affinity; (+) represents 5-9% positive yeast cells which is characterized by positive antibody binding with very low affinity; -/+ represents less than 5% positive yeast cells which is characterized by ambiguous antibody binding, - represents 0% positive yeast cells which is characterized by no binding; nt = not tested.

Figure 5A is an alignment between the amino acid sequence of 1 1 B 1 (SEQ ID NO: 77), 1 1 C8 (SEQ ID NO:92) and 1 1 H3 (SEQ ID NO:102) heavy chain variable regions where " * " means that the residues in that column are identical in all sequences in the alignment, " : " means that conserved substitutions have been observed (Sievers F. et al., Molecular Systems Biology, 1 1 Oct 201 1 , 7:539).

Figure 5B is an alignment between the amino acid sequence of 4B3 (SEQ ID NO:27) and 5D8 (SE ID NO:47) light chain variable regions, where " * " means that the residues in that column are identical in all sequences in the alignment, " : " means that conserved substitutions have been observed and " . " means that semi-conserved substitutions are observed.

Figure 5C is an alignment between the amino acid sequence of 4B3 (SEQ ID NO:32) and 5D8 (SEQ ID NO:52) heavy chain variable regions.

Figure 5D is an alignment between the amino acid sequence of 4B3 (SEQ ID:27), 5D8 (SEQ ID:47) and 9C9 (SEQ ID:57) light chain variable regions where " * " means that the residues in that column are identical in all sequences in the alignment, " : " means that conserved substitutions have been observed and " . " means that semi-conserved substitutions are observed.

Figures 6A-F show results of the effect of anti-EGFRvlll antibodies as DM1- (A, B and C) or MMAE-conjugates (D, E and F) on cell viability in glioblastoma cells expressing wild type EGFR (U87 wt) or EGFRvlll (U87 EGFRvlll or DKMG EGFRvlll) as indicated.

Figure 7 is a graph showing tumor growth curve in U87MG EGFRvlll tumor-bearing mice treated twice (day 0 and 4) with selected ADCs at 5 mg/kg based on DAR=3. Tumor volumes (mm3) were recorded every three days. Each data point represents mean ± SEM, (n=8).

Figure 8A is a graph showing tumor growth inhibition in U87MG EGFRvlll tumor-bearing mice treated twice (day 0 and 4) with selected DM1 -ADCs at 3 mg/kg based on DAR=3. Tumor volumes (mm3) were recorded every three days. Each data point represents mean ± SEM (n=12).

Figure 8B is a graph showing tumor growth inhibition in U87MG EGFRvlll tumor-bearing mice treated twice (day 0 and 4) with selected MMAE-ADCs at 3 mg/kg based on DAR=3.

Tumor volumes (mm3) were recorded every three days. Each data point represents mean ±

SEM (n=12).

Figure 9: Schematic illustrating the synthetic assembly and sequence of the 5G6 or 4E1 1 antigen-binding domain in a synthetic chimeric antigen receptor (CAR) construct.

Figure 10: Graph illustrating the in vitro functionality of EGFRvlll CAR-T constructs. Jurkat cells electroporated with various CAR constructs (EGFRvlll 5G6 CAR, EGFRvlll 4E1 1 CAR, or control CD19-specific FMC63 CAR) were exposed to target cells with (U87vlll) or without (U87, OVCAR3 and A20) EGFRvlll target expression for 24 hours. The level of cell activation was measured by quantifying surface expression of CD69 on Jurkat cells (CD45 positive) by flow cytometry.

Figure 11 : Graph illustrating repression of target cell growth in CAR transduced T-cell/target cell co-cultures. Human primary peripheral blood derived T cells were transduced with EGFRvlll-specific CAR lentivirus (4E1 1-CAR-T or 5G6-CAR-T), CD19-specific CAR lentivirus (FMC63) or treated similarly in the absence of lentivirus (Mock) and grown for several days in culture. CAR transduced or non-transduced T cells were then placed in co-culture with EGFRvlll antigen expressing target cells which express nuclear localized mKate2-fluorescent protein (U87vlll). Cells were then examined using live fluorescence microscopy (Incucyte™, Sartorius). Graph depicts the relative target cell growth over 6 days as measured via automated counting of mKate2+ cells.

Figure 12: Graphs illustrating tumor growth (left panels) and survival (right panels) of tumor-bearing NOD/SCI D/I L-2Ry-null (NSG) mice. NSG mice (Jackson Laboratory, Barr Harbor, ME) were injected subcutaneously with 1x106 U87vlll human glioblastoma cells expressing EGFRvlll. On day 7 post tumor cell injection, mice were given either primary human T cells transduced with EGFRvlll-4E1 1 CAR or left untreated. Tumour growth was then monitored by caliper measurements (Figure 12A). Tumor size (the length and the width) was measured using a digital vernier caliper. T umor volume was calculated by using the formula: Tumor volume = (0.4) (ab2), where a = large diameter and b= smaller diameter. Survival is defined as time to humane endpoint (defined as a tumour volume exceeding 2000mm3) with and without CAR-T treatment (Figure 12B).

Figure 13: Schematic illustrating potential bi-specific T-cell engagers and bispecific killer cell engagers.

Figure 14: Graph illustrating screening of bi-specific T cell engager activity with EGFRvlll-specific construct containing 4E1 1-scFV sequence linked to OKT3 human CD3-specific scFV. Supernatant from human embryonic kidney (HEK293) cells transiently expressing 4E1 1-OKT3 bi specific engager construct were transferred to wells containing Jurkat cells and varying doses of antigen expressing target cells (U87vlll). Target-induced activation of in the presence or absence of bispecific T-cell engager was measured by examining the level of CD69 expression using human CD69-specific antibody staining and flow cytometry. The fold change in CD69 expression with and without bispecific-T cell engager over varying doses of target cell is shown here.

Figure 15: Graph illustrating repression of target cell growth in T-cell/target cell co-cultures in the presence of a bi-specific T cell engager constructs containing 4E1 1-scFV sequence linked to OKT3 human CD3-specific scFV. A control bi-specific T cell engager composed of human -CD19-specific scFv linked to OKT3 is shown for comparison. Supernatant from human embryonic kidney cells transiently expressing 4E1 1 -OKT3 bi-specific T cell engager construct or the CD19-OKT3 bi-specific T cell engager construct were transferred to wells containing primary blood derived T cells and EGFRvlll antigen expressing target cells which express nuclear localized mKate2-fluorescent protein (U87vlll). Cells were then examined using live fluorescence

microscopy (Incucyte™, Sartorius, USA). Graph depicts the relative target cell growth over 72 hours as measured via automated counting of mKate2+ cells.

DETAILED DESCRIPTION

As used herein the term“EGFRvIN” refers to epidermal growth factor receptor variant III. The terms“EGFRvIN” and“vIM” are used interchangeably.

As used herein the term“EGFR” refers to human epidermal growth factor receptor. The term“wt EGFR”,“WT EGFR”,“EGFR WT” or“EGFR wt” are used interchangeably and refers to wild type EGFR.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the disclosure (especially in the context of the claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.

Unless specifically stated or obvious from context, as used herein the term “or” is understood to be inclusive and covers both“or” and“and”.

The term“and/or” where used herein is to be taken as specific disclosure of each of the specified features or components with or without the other.

The terms "comprising", "having", "including", and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to") unless otherwise noted. The term “consisting of” is to be construed as close-ended.

As used herein the term“native” with respect to a protein such as EGFRvIN or EGFR refers to the natural conformation of the protein and includes proteins that are properly folded and/or functional.

As used herein the term“denatured” with respect to a protein such EGFRvIN or EGFR refers to a protein that has lost its natural conformation and may entail for example, a loss in the tertiary and secondary structure.

As used herein the expression “a peptide comprising or consisting of an EGFRvIN fragment” means that the peptide may comprise a portion other than the EGFRvIN fragment or that it consists in the EGFRvIN fragment.

As used herein the term“binds to an epitope comprising amino acid residues” means that the amino acid residue is either part of the epitope or that it is necessary for binding of the antibody.

As used herein the term“fails to bind to” a peptide or protein means that the antibody or antigen binding fragment a) does not bind significantly to the peptide or protein when expressed recombinantly or in cells, b) no detectable binding is observed, c) has similar binding property as a negative control antibody, d) does not binds specifically or e) binds with a value between 0% and 15% as determined by the flow cytometry experiments carried out in Example 10.

As used herein the term“autologous” refers to material derived from the same individual.

As used herein the term“antigen-binding domain” refers to the domain of an antibody or of an antigen-binding fragment which allows specific binding to an antigen.

As used herein, the term “antibody” encompasses monoclonal antibody, polyclonal antibody, humanized antibody, chimeric antibody, human antibody, single domain antibody (such as a VHH, VH, VL, nanobody, or any camelid or llama single domain antibody), multispecific antibody (e.g., bispecific antibodies) etc. The term“antibody” encompasses molecules that have a format similar to those occurring in nature (e.g., human IgGs, etc.). The term“antibody”, also referred to in the art as“immunoglobulin” (Ig), as used herein refers to a protein constructed from paired heavy and light polypeptide chains; various Ig isotypes exist, including IgA, IgD, IgE, IgG, and IgM. When an antibody is correctly folded, each chain folds into a number of distinct globular domains joined by more linear polypeptide sequences. For example, the immunoglobulin light chain folds into a variable (VL) and a constant (CL) domain, while the heavy chain folds into a variable (VH) and three constant (CH1 , CH2, CH3) domains. Interaction of the heavy and light chain variable domains (VH and VL) results in the formation of an antigen-binding region (Fv). Each domain has a well-established structure familiar to those of skill in the art.

Typically, an antibody is constituted from the pairing of two light chains and two heavy chains. Different antibody isotypes exist, including IgA, IgD, IgE, IgG and IgM. Human IgGs are further divided into four distinct sub-groups namely; lgG1 , lgG2, lgG3 and lgG4. Therapeutic antibodies are generally developed as lgG1 or lgG2.

In an exemplary embodiment, the antibody or antigen-binding fragment of the present disclosure may comprise, for example, a human lgG1 constant region or a fragment thereof. In another exemplary embodiment, the antibody or antigen-binding fragment of the present disclosure may comprise, for example, a human lgG2 constant region or a fragment thereof. Constant regions of other antibody subtypes are also contemplated.

The light chain and heavy chain of human antibody IgG isotypes each comprise a variable region having 3 hypervariable regions named complementarity determining regions (CDRs). The

light chain CDRs are identified herein as CDRL1 or L1 , CDRL2 or L2 and CDRL3 or L3. The heavy chain CDRs are identified herein as CDRH1 or H1 , CDRH2 or H2 and CDRH3 or H3. Complementarity determining regions are flanked by framework regions (FR) in the order: FR1 -CDR1 -FR2-CDR2-FR3-CDR3-FR4. The light and heavy chain variable regions are responsible for binding the target antigen and can therefore show significant sequence diversity between antibodies. The constant regions show less sequence diversity and are responsible for binding a number of natural proteins to elicit important biochemical events. The variable region of an antibody contains the antigen-binding determinants of the molecule, and thus determines the specificity of an antibody for its target antigen. The majority of sequence variability occurs in the CDRs which combine to form the antigen-binding site and contribute to binding and recognition of an antigenic determinant. The framework regions may play a role in the proper positioning and alignment in three dimensions of the CDRs for optimal antigen-binding. The specificity and affinity of an antibody for its antigen is determined by the structure of the hypervariable regions, as well as their size, shape, and chemistry of the surface they present to the antigen. Various schemes exist for identification of the regions of hypervariability, the two most common being those of Kabat and of Chothia and Lesk. Kabat et al (1991 ) define the“complementarity-determining regions” (CDR) based on sequence variability at the antigen-binding regions of the VH and VL domains. Chothia and Lesk (1987) define the“hypervariable loops” (H or L) based on the location of the structural loop regions in the VH and VL domains. These individual schemes define CDR and hypervariable loop regions that are adjacent or overlapping, those of skill in the antibody art often utilize the terms“CDR” and “hypervariable loop” interchangeably, and they may be so used herein. The CDR/loops are identified herein according to the Kabat scheme.

Recombinant DNA technology now allows the design of various antibody format such as single chain antibodies (e.g., single domain), diabody, minibody, nanobody and the like which are encompassed by the present disclosure.

An“antigen-binding fragment” as referred to herein may include any suitable antigen binding fragment known in the art. The antigen-binding fragment may be a naturally-occurring fragment or may be obtained by manipulation of a naturally-occurring antibody or by using recombinant methods. For example, an antibody fragment may include, but is not limited to a Fv, single-chain Fv (scFv; a molecule consisting of VL and VH connected with a peptide linker), Fab, F(ab’)2, single-domain antibody (sdAb; a fragment composed of a single VL or VH), and multivalent presentations of any of these. Antibody fragments such as those just described may require linker sequences, disulfide bonds, or other type of covalent bond to link different portions of the fragments; those of skill in the art will be familiar with the requirements of the different types of fragments and various approaches and various approaches for their construction.

Antigen-binding fragments thereof of the present disclosure encompass molecules having an antigen-binding site comprising amino acid residues that confer specific binding to an antigen (e.g., one or more CDRs).

Exemplary embodiments of antigen-binding fragments disclosure thus includes without limitation (i) a Fab fragment, a monovalent fragment consisting of the VL, VH, CL and Cm domains; (ii) a F(ab')2 fragment, a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) a Fd fragment consisting of the VH and Cm domains; (iv) a Fv fragment consisting of the VL and VH domains of a single arm of an antibody, (v) a dAb fragment (Ward et al., (1989) Nature 341 :544-546), which consists of a VH domain; and (vi) an isolated complementarity determining region (CDR), e.g., VH CDR3.

Specific embodiments of antigen-binding fragments may include for example, a scFv, a Fab, a Fab' or a (Fab')2.

The term“humanized antibody” encompasses fully humanized antibody (/'.e., frameworks are 100% humanized) and partially humanized antibody (e.g., at least one variable region contains one or more amino acids from a human antibody, while other amino acids are amino acids of a non-human parent antibody). Typically, a“humanized antibody” contains CDRs of a non-human parent antibody (e.g., mouse, rat, rabbit, non-human primate, etc.) and frameworks that are identical to those of a natural human antibody or of a human antibody consensus. In such instance, those“humanized antibodies” are characterized as fully humanized. A“humanized antibody” may also contain one or more amino acid substitutions that have no correspondence to those of the human antibody or human antibody consensus. Such substitutions include, for example, back-mutations (e.g., re-introduction of non-human amino acids) that may preserve the antibody characteristics (e.g., affinity, specificity etc.). Such substitutions are usually in the framework region. A“humanized antibody” usually also comprise a constant region (Fc) which is typically that of a human antibody. Typically, the constant region of a“humanized antibody” is identical to that of a human antibody. A humanized antibody may be obtained by CDR grafting (Tsurushita et al, 2005; Jones et al, 1986; Tempest et al, 1991 ; Riechmann et al, 1988; Queen et al, 1989). Such antibody is considered as fully humanized.

The term“chimeric antibody” refers to an antibody having a constant region from an origin distinct from that of the parent antibody. The term“chimeric antibody” encompasses antibodies

having a human constant region. Typically, a“chimeric antibody” is composed of variable regions originating from a mouse antibody and of a human constant region.

The term“hybrid antibody” refers to an antibody comprising one of its heavy or light chain variable region (its heavy or light chain) from a certain type of antibody (e.g., humanized) while the other of the heavy or light chain variable region (the heavy or light chain) is from another type (e.g., murine, chimeric).

Antibodies and/or antigen-binding fragments of the present disclosure may originate, for example, from a mouse, a rat or any other mammal or from other sources such as through recombinant DNA technologies. Antibodies or antigen-binding fragment of the present disclosure may include for example, a synthetic antibody, a non-naturally occurring antibody, an antibody obtained following immunization of a non-human mammal etc.

Antibodies or antigen-binding fragments thereof of the present disclosure may be isolated and/or substantially purified.

Variant antipen-bindinp apent

The present disclosure also encompasses variants of the antigen-binding agents described herein.

More particularly, the present disclosure encompasses variants of the antibodies or antigen-binding fragments, CARs and BiTEs described herein. Variants (e.g., antibodies or antigen-binding fragments, CARs, BiTEs and the like) include those having a variation in their amino acid sequence, e.g., in one or more CDRs, in one or more framework regions and/or in the constant region. Variants (e.g., antibodies or antigen-binding fragments, CARs, BiTEs and the like) included in the present disclosure are those having, for example, similar or improved binding affinity in comparison with the original antibody or antigen-binding fragment.

Variants encompassed by the present disclosure are those which may comprise an insertion, a deletion or an amino acid substitution (conservative or non-conservative). These variants may have at least one amino acid residue in its amino acid sequence removed and a different residue inserted in its place.

More particularly, variants encompassed by the present disclosure include those having a light chain variable region and/or a heavy chain variable region having at least 80% sequence identity with the light chain variable region and/or a heavy chain variable region of the antibody or antigen-binding variant disclosed herein. The CDRs of the variant antibody may be identical to those of the antibody or antigen-binding fragments disclosed herein.

Also encompassed by the present disclosure are variants having CDRs amino acid residues that are identical and framework regions that are at least 80% sequence identical to those of the antibody or antigen-binding fragment disclosed herein.

Conservative substitutions may be made by exchanging an amino acid residue (of a CDR, variable chain, framework region or constant region, etc.) from one of the groups listed below (group 1 to 6) for another amino acid of the same group.

Other exemplary embodiments of conservative substitutions are shown in the table below. (group 1 ) hydrophobic: norleucine, methionine (Met), Alanine (Ala), Valine (Val),

Leucine (Leu), Isoleucine (lie)

(group 2) neutral hydrophilic: Cysteine (Cys), Serine (Ser), Threonine (Thr)

(group 3) acidic: Aspartic acid (Asp), Glutamic acid (Glu)

(group 4) basic: Asparagine (Asn), Glutamine (Gin), Histidine (His), Lysine (Lys), Arginine (Arg)

(group 5) residues that influence chain orientation: Glycine (Gly), Proline (Pro); and

(group 6) aromatic: Tryptophan (Trp), Tyrosine (Tyr), Phenylalanine (Phe)

Non-conservative substitutions will entail exchanging a member of one of these groups for another.



Percent identity is indicative of amino acids which are identical in comparison with the original peptide and which may occupy the same or similar position. Percent similarity will be indicative of amino acids which are identical and those which are replaced with conservative amino acid substitution in comparison with the original peptide at the same or similar position.

Generally, the degree of similarity and identity between variable chains has been determined herein using the Blast2 sequence program (Tatiana A. Tatusova, Thomas L. Madden (1999), "Blast 2 sequences - a new tool for comparing protein and nucleotide sequences", FEMS Microbiol Lett. 174:247-250) using default settings, i.e., blastp program, BLOSUM62 matrix (open gap 11 and extension gap penalty 1 ; gapx dropoff 50, expect 10.0, word size 3) and activated filters.

A“substantially identical” sequence may comprise one or more conservative amino acid mutations, or amino acid deletions that allow for biologically functional activity to be maintained. It is known in the art that one or more conservative amino acid mutations to a reference sequence may yield a variant peptide with no substantial change in physiological, chemical, physico chemical or functional properties compared to the reference sequence; in such a case, the reference and variant sequences would be considered“substantially identical” polypeptides.

Variants of the present disclosure therefore comprise those which may have at least 70%, 75%, 80%, 81 %, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity with an original sequence or a portion of an original sequence.

Nucleic acids, vectors and cells

Antibodies are usually made in cells allowing expression of the light chain and heavy chain expressed from a vector(s) comprising a nucleic acid sequence encoding the light chain and/or heavy chain.

The present disclosure therefore encompasses nucleic acids capable of encoding any of the CDRs, light chain variable regions, heavy chain variable regions, light chains, heavy chains described herein.

As used herein, the term“nucleic acid’ refers to RNA, DNA, cDNA and the like.

Due to the inherent degeneracy of the genetic code, other nucleic acid sequences that encode the same amino acid sequence may be produced and used to express the antibody or antigen-binding fragments thereof of the present disclosure. The nucleotide sequences may be engineered using methods generally known in the art in order to alter the nucleotide sequences for a variety of purposes including, but not limited to, modification of the cloning, processing, and/or expression of the gene product. DNA shuffling by random fragmentation and PCR reassembly of gene fragments and synthetic oligonucleotides may be used to engineer the nucleotide sequences. For example, oligonucleotide-mediated site-directed mutagenesis may be used to introduce mutations that create new restriction sites, alter glycosylation patterns, change codon preference, produce splice variants, and so forth.

In yet another aspect, the present disclosure relates to a vector comprising the nucleic acids described herein.

In accordance with the present disclosure, the vector may be an expression vector.

The expression vector usually contains the elements for transcriptional and translational control of the inserted coding sequence in a particular host. These elements may include regulatory sequences, such as enhancers, constitutive and inducible promoters, and 5' and 3' un translated regions. Methods that are well known to those skilled in the art may be used to construct such expression vectors. These methods include in vitro recombinant DNA techniques, synthetic techniques, and in vivo genetic recombination.

The light chain variable region and the heavy chain variable region of the antibody or antigen-binding fragment thereof may be encoded by the same nucleic acid molecule (e.g., same vector) or by separate molecules (e.g., separate vectors).

The present disclosure therefore provides a set of vectors, where one of the vectors is capable of expressing the light chain or light chain variable region and the other vector is capable of expressing the heavy chain or heavy chain variable region.

Additional aspects of the disclosure relate to kits which comprising a first vial containing a nucleic acid or vector encoding the light chain or the light chain variable region of the antibody or antigen-binding fragment thereof of the present disclosure and second vial containing a nucleic acid or vector encoding the heavy chain or the heavy chain variable region of the antibody or antigen-binding fragment thereof.

In another aspect the present disclosure relates to an isolated cell which may comprise the nucleic acids, vectors, antibodies or antigen-binding fragment described herein.

The isolated cell may comprise a nucleic acid encoding a light chain variable region and a nucleic acid encoding a heavy chain variable region either on separate vectors or on the same vector. The isolated cell may also comprise a nucleic acid encoding a light chain and a nucleic acid encoding a heavy chain either on separate vectors or on the same vector.

In accordance with the present disclosure, the cell may be capable of expressing, assembling and/or secreting an antibody or antigen-binding fragment thereof.

Also, in accordance with the present disclosure, the cell may comprise and/or may express the antibody described herein.

Further in accordance with the disclosure, the cell may comprise a nucleic acid encoding a light chain variable region and a nucleic acid encoding a heavy chain variable region.

Production of the antibodies or antiqen-bindinq fraqments in cells

The antibodies that are disclosed herein can be made by a variety of methods familiar to those skilled in the art including hybridoma methodology or recombinant DNA methods.

Conventional hybridoma technology entails immunizing a rodent with an antigen, isolating and fusing spleen cells with myeloma cells lacking HGPRT expression and selecting hybrid cells by hypoxanthine, aminopterin and thymine (HAT) containing media. Hybridoma are screened to identify those producing antibodies that are specific for a given antigen. The hybridoma is expanded and cloned. The nucleic acid sequence of the light chain and heavy chain variable regions is obtained by standard sequencing methodology and expression vectors comprising the light chain and heavy chain nucleic acid sequence of an antibody are generated.

For recombinant expression of antibodies, host cells are transformed with a vector or a set of vectors comprising the nucleic acid sequence of the light chain and heavy chain of the antibody or antigen-binding fragment thereof (on the same vector or separate vectors).

For long-term production of recombinant proteins in mammalian systems, cell lines stably expressing proteins may be obtained. For example, nucleotide sequences able to encode any one of a light and heavy immunoglobulin chains described herein may be transformed into cell lines using expression vectors that may contain viral origins of replication and/or endogenous expression elements and a selectable or visible marker gene on the same or on a separate vector. The disclosure is not to be limited by the vector or host cell employed. In certain embodiments of the present disclosure, the nucleotide sequences able to encode any one of a light and heavy immunoglobulin chains described herein may each be ligated into a separate expression vector and each chain expressed separately. In another embodiment, both the light and heavy chains able to encode any one of a light and heavy immunoglobulin chains described herein may be ligated into a single expression vector and expressed simultaneously.

Immunological methods for detecting and measuring the expression of polypeptides are known in the art. Examples of such techniques include enzyme-linked immunosorbent assays (ELISAs), radioimmunoassays (RIAs), fluorescence activated cell sorting (FACS) or flow cytometry. Those of skill in the art may readily adapt these methodologies to the present disclosure.

Different host cells that have specific cellular machinery and characteristic mechanisms for post-translational activities (e.g., Chinese Hamster Ovary (CHO), HeLa, MDCK, HEK293, and Wl-38) are available commercially and from the American Type Culture Collection (ATCC) and may be chosen to ensure the correct modification and processing of the expressed polypeptide.

Typically, antibody or antigen-binding fragments thereof are produced in CHO cells, NS0 murine myeloma cells, PER.C6® human cells.

The present disclosure relates to a method of making an antibody or an antigen-binding fragment thereof comprising expressing the light chain and heavy chain of the antibody or antigen binding fragment of the present disclosure in cultured cells.

The method may further comprise purifying or isolating the antibody or antigen-binding fragment of the present disclosure. The method may also further comprise conjugating the antibody or antigen-binding fragment of the present disclosure to a cargo molecule such as a therapeutic or detectable moiety.

Antibody conjugates

The antibody or antigen-binding fragment thereof of the present disclosure may be linked to a cargo molecule. Exemplary embodiments of cargo molecules include without limitation a therapeutic moiety a detectable moiety, a polypeptide (e.g., peptide, enzyme, growth factor), a polynucleotide, liposome, nanoparticle, nanowire, nanotube, quantum dot, etc.

More particularly, the antibody or antigen-binding fragment thereof of the present disclosure may be conjugated with a therapeutic moiety. The therapeutic moiety is usually attached to the antibody via a linker which may be cleavable or non-cleavable.

Included amongst the list of therapeutic moieties are cytotoxic agents, cytostatic agents, anti-cancer agents (chemotherapeutics) and radiotherapeutics (e.g. radioisotopes).

Exemplary embodiments of cytotoxic agents include, without limitation, alpha-amanitine, cryptophycin, duocarmazine, duocarmycin, chalicheamicin, deruxtecan, pyrrolobenzodiazepine (PBD), dolastatins, pseudomonas endotoxin, ricin, auristatins (e.g., monomethyl auristatin E, monomethyl auristatin F), maytansinoids (e.g., mertansine), pyrrolobenzodiazepine (PBD) and analogues.

Exemplary embodiments of radiotherapeutics include without limitation, Yttrium-90, Scandium-47, Rhenium-186, Iodine-131 , Iodine-125, and many others recognized by those skilled in the art (e.g., lutetium (e.g., Lu177), bismuth (e.g., Bi213), copper (e.g., Cu67), astatine-21 1 (21 1 At), actinium 225 (Ac-225), etc).

Exemplary embodiments of chemotherapeutics include, without limitation, 5-fluorouracil, adriamycin, irinotecan, taxanes, carboplatin, cisplatin, etc.

The antibody or antigen-binding fragment of the present disclosure may also be conjugated with a detectable moiety (i.e., for detection or diagnostic purposes).

A “detectable moiety” comprises agents detectable by spectroscopic, photochemical, biochemical, immunochemical, chemical and/or other physical means. A detectable moiety may be coupled either directly and/or indirectly (for example via a linkage, such as, without limitation, a DOTA or NHS linkage) to antibodies and antigen-binding fragments thereof of the present disclosure using methods well known in the art. A wide variety of detectable moieties may be used, with the choice depending on the sensitivity required, ease of conjugation, stability requirements and available instrumentation. A suitable detectable moiety include, but is not limited to, a fluorescent label, a radioactive label (for example, without limitation, 125l, In111, Tc", I131 and including positron emitting isotopes for PET scanner etc.), a nuclear magnetic resonance active label, a luminescent label, a chemiluminescent label, a chromophore label, an enzyme label (for example and without limitation horseradish peroxidase, alkaline phosphatase, etc.), quantum dots and/or a nanoparticle. Detectable moiety may cause and/or produce a detectable signal thereby allowing for a signal from the detectable moiety to be detected.

Chimeric Antigen Receptors and other Immunotherapeutics

The sequence of the antibodies and antigen-binding fragments thereof of the present disclosure may be used to generate chimeric antigen receptors (CARs), bi-specific T-cell engagers (BiTE) or other immunotherapeutics such as for example and without limitations, bispecific killer cell engagers (BiKE), trispecific killer cell engagers (TriKE) or any immunotherapeutic compounds.

The CARs of the present disclosure may comprise for example, a) an antigen-binding domain of an antibody that specifically binds to epidermal growth factor receptor variant III (EGFRvlll), b) optionally a spacer, c) a transmembrane domain, d) optionally at least one costimulatory domain, and e) at least one intracellular signaling domain.

Chimeric antigen receptors may also comprise a hinge region or spacer which connects the antigen-binding domain and the transmembrane domain. The spacer may allow a better presentation of the antigen-binding domain at the surface of the cell.

In accordance with the present disclosure, the spacer may be optional. Alternatively, the spacer may comprise for example, between 1 to 200 amino acid residues, typically between 10 to 100 amino acid residues and more typically between 25 to 50 amino acid residues. The spacer may originate from a human protein.

In accordance with the present disclosure, the spacer or hinge region may be, for example and without limitation a CD8 hinge (e.g., mouse, human CD8) or an IgG hinge (a human immunoglobulin hinge) or combination thereof.

Exemplary embodiments of transmembrane domains include, for example and without limitation, the alpha, beta or CD3zeta chain of the T-cell receptor complex, CD28, CD27, CD3 epsilon, CD45, CD4, CD5, CD8, CD9, CD16, CD22, CD33, CD37, CD64, CD80, CD86, CD134, CD137, CD154.

In some embodiments, the transmembrane domain may include at least the transmembrane region(s) of, e.g., KIRDS2, 0X40, CD2, CD27, LFA-1 (CD 1 1 a, CD18), ICOS (CD278), 4-1 BB (CD137), GITR, CD40, BAFFR, HVEM (LIGHTR), SLAMF7, NKp80 (KLRF1 ), NKp44, NKp30, NKp46, CD 160, CD 19, IL2R beta, IL2R gamma, IL7R a, ITGA1 , VLA1 , CD49a, ITGA4, IA4, CD49D, ITGA6, VLA-6, CD49f, ITGAD, CD1 d, ITGAE, CD103, ITGAL, CD1 1 a, L FA-1 , ITGAM, CD1 1 b, ITGAX, CD1 1 c, ITGB 1 , CD29, ITGB2, CD18, LFA-1 , ITGB7, TNFR2, DNAM1 (CD226), SLAMF4 (CD244, 2B4), CD84, CD96 (Tactile), CEACAM1 , CRT AM, Ly9 (CD229), CD160 (BY55), PSGL1 , CD100 (SEMA4D), SLAMF6 (NTB-A, Lyl08), SLAM (SLAMF1 , CD150, IPO-3), BLAME (SLAMF8), SELPLG (CD162), LTBR, PAG/Cbp, NKG2D, NKG2C.

A particular embodiment of transmembrane domain is the transmembrane domain of

CD28.

The costimulatory domain may be, for example and without limitation, from CD28, CD27, 4-1 BB, 0X40, CD7, B7-1 (CD80), B7-2 (CD86), CD30, CD40, PD-1 , ICOS, lymphocyte function-associated antigen- 1 (LFA-1 ), CD2, LIGHT, NKG2C, B7-H3, a ligand that specifically binds with CD83, CDS, ICAM-1 , GITR, BAFFR, HVEM (LIGHTR), SLAMF7, NKp80 (KLRF1 ), CD160, CD19, CD4, CD8alpha, CD8beta, IL2R beta, IL2R gamma, IL7R alpha, ITGA4, VLA1 , CD49a, ITGA4, IA4, CD49D, ITGA6, VLA-6, CD49f, ITGAD, CD1 d, ITGAE, CD103, ITGAL, CD1 1 a, LFA-1 , ITGAM, CD1 1 b, ITGAX, CD1 1 c, ITGB1 , CD29, ITGB2, CD18, LFA-1 , ITGB7, TNFR2, TRANCE/RANKL, DNAM1 (CD226), SLAMF4 (CD244, 2B4), CD84, CD96 (Tactile), CEACAM1 , CRTAM, Ly9 (CD229), CD160 (BY55), PSGL1 , CD100 (SEMA4D), CD69, SLAMF6 (NTB-A, Lyl08), SLAM (SLAMF1 , CD150, IPO-3), BLAME (SLAMF8), SELPLG (CD162), LTBR, LAT, GADS, SLP-76, PAG/Cbp, NKp44, NKp30, NKp46, and NKG2D or a combination thereof.

The intracellular signaling domain may be, for example and without limitation, from CD3 zeta, CD3 gamma, CD3 delta, CD3 epsilon, common FcR gamma (FCERIG), FcR beta (Fc Epsilon Rib), CD79a, CD79b, Fcgamma Rlla, DAP10, or DAP12.

In order to be targeted to the secretory pathway, the chimeric antigen receptor may also comprise a signal peptide such as, for example, a signal peptide of CD28 or any other signal peptide suitable for immune cells. The signal peptide is cleaved (cleavable).

BiTE, BiKE and TriKE molecules may comprise an antigen-binding domain (e.g. scFv) that specifically binds to EGFRvlll and another domain (scFv) that binds to specific immune cells including but not limited to a T-cell specific molecule (e.g., CD3) and NK-cell surface molecules (e.g. CD16). These generally comprise multiple scFvs connected in tandem by flexible linkers.

Pharmaceutical compositions

The present disclosure also relates to pharmaceutical compositions comprising the antibodies or antigen-binding fragments (conjugated or not) disclosed herein.

In addition to the active ingredients, a pharmaceutical composition may contain pharmaceutically acceptable carriers comprising without limitation, water, PBS, salt solutions, gelatins, oils, alcohols, and other excipients and auxiliaries that facilitate processing of the active compounds into preparations that may be used pharmaceutically. In other instances, such preparations may be sterilized.

As used herein, "pharmaceutical composition" means therapeutically effective amounts of the agent together with pharmaceutically acceptable diluents, preservatives, solubilizers, emulsifiers, adjuvant and/or carriers. A "therapeutically effective amount" as used herein refers to that amount which provides a therapeutic effect for a given condition and administration regimen. Such compositions are liquids or lyophilized or otherwise dried formulations and include diluents of various buffer content (e.g., Tris-HCI., acetate, phosphate), pH and ionic strength, additives such as albumin or gelatin to prevent absorption to surfaces, detergents (e.g., Tween 20, Tween 80, Pluronic F68, bile acid salts). Solubilizing agents (e.g., glycerol, polyethylene glycerol), anti oxidants (e.g., ascorbic acid, sodium metabisulfite), preservatives (e.g., thimerosal, benzyl alcohol, parabens), bulking substances or tonicity modifiers (e.g., lactose, mannitol), covalent attachment of polymers such as polyethylene glycol to the protein, complexation with metal ions, or incorporation of the material into or onto particulate preparations of polymeric compounds such as polylactic acid, polyglycolic acid, hydrogels, etc., or onto liposomes, microemulsions, micelles, unilamellar or multilamellar vesicles, erythrocyte ghosts, or spheroplasts. Such compositions will influence the physical state, solubility, stability, rate of in vivo release, and rate of in vivo clearance. Controlled or sustained release compositions include formulation in lipophilic depots (e.g., fatty acids, waxes, oils). Also comprehended by the disclosure are particulate compositions coated with polymers (e.g., poloxamers or poloxamines). Other embodiments of the compositions of the disclosure incorporate particulate forms protective coatings, protease inhibitors or permeation enhancers for various routes of administration, including parenteral, pulmonary, nasal, oral, vaginal, rectal routes. In one embodiment the pharmaceutical composition is administered parenterally, paracancerally, transmucosally, transdermally, intramuscularly, intravenously, intradermally, subcutaneously, intraperitonealy, intraventricularly, intracranially and intratumorally.

Further, as used herein "pharmaceutically acceptable carrier" or "pharmaceutical carrier" are known in the art and include, but are not limited to, 0.01 -0.1 M or 0.05 M phosphate buffer or 0.8 % saline. Additionally, such pharmaceutically acceptable carriers may be aqueous or non-aqueous solutions, suspensions, and emulsions. Examples of non-aqueous solvents are propylene glycol, polyethylene glycol, vegetable oils such as olive oil, and injectable organic esters such as ethyl oleate. Aqueous carriers include water, alcoholic/aqueous solutions, emulsions or suspensions, including saline and buffered media. Parenteral vehicles include sodium chloride solution, Ringer's dextrose, dextrose and sodium chloride, lactated Ringer's or fixed oils. Intravenous vehicles include fluid and nutrient replenishers, electrolyte replenishers such as those based on Ringer's dextrose, and the like. Preservatives and other additives may also be present, such as, for example, antimicrobials, antioxidants, collating agents, inert gases and the like.

For any compound, the therapeutically effective dose may be estimated initially either in cell culture assays or in animal models such as mice, rats, rabbits, dogs, or pigs. An animal model may also be used to determine the concentration range and route of administration. Such information may then be used to determine useful doses and routes for administration in humans. These techniques are well known to one skilled in the art and a therapeutically effective dose refers to that amount of active ingredient that ameliorates the symptoms or condition. Therapeutic efficacy and toxicity may be determined by standard pharmaceutical procedures in cell cultures or with experimental animals, such as by calculating and contrasting the ED5o (the dose therapeutically effective in 50% of the population) and LD5o (the dose lethal to 50% of the population) statistics. Any of the therapeutic compositions described above may be applied to any subject in need of such therapy, including, but not limited to, mammals such as dogs, cats, cows, horses, rabbits, monkeys, and humans.

The pharmaceutical compositions utilized in this disclosure may be administered by any number of routes including, but not limited to, oral, intravenous, intramuscular, intra-arterial, intramedullary, intrathecal, intraventricular, transdermal, subcutaneous, intraperitoneal, intranasal, enteral, topical, sublingual, or rectal means.

Additional aspects of the disclosure relate to kits which may include vial(s) containing one or more antibodies or antigen-binding fragments or antibody drug conjugates described herein.

Methods of use

Aspects of the disclosure comprise administering antibodies or antigen binding fragments thereof, CAR, BiTE, BiKE or TriKE molecules to a subject in need.

Other aspects of the disclosure comprise administering immune cells engineered to express the CAR, BiTE, BiKE or TriKE molecules to a subject in need.

The CAR, BiTE, BiKE or TriKE constructs of the present disclosure may be used to re target engineered immune cells towards EGFRvlll-positive tumors.

The engineered immune cells may be administered to a subject in need.

In accordance with an aspect of the present disclosure, immune cells are isolated from the subject, engineered to express the CAR, BiTE, BiKE or TriKE construct and re-administered to the same subject.

The antibody or antigen-binding fragment thereof of the present disclosure may be used in an unconjugated form or conjugated with a therapeutic moiety in the treatment of cancer.

More particularly, the antibody or antigen-binding fragment thereof of the present disclosure may be used to inhibit the growth of tumor cells expressing EGFRvlll. Antibody drug conjugates and radioimmunoconjugates are especially contemplated for such purposes.

The present disclosure more particularly relates to a method of treating a subject having or suspected of having cancer by administering the antibody or antigen-binding fragment thereof or an antibody drug conjugate disclosed herein.

The antibody or antigen-binding fragment thereof or antibody drug conjugate may be administered as a pharmaceutical composition either alone or in combination with other anti cancer drugs.

As used herein the term“subject” encompasses humans and animals such as non-human primates, cattle, rabbits, mice, rats, sheep, goats, horses, birds, etc. The term“subject” particularly encompasses humans.

Subjects in need which would benefit from treatment include humans having tumor cells expressing EGFRvlll. More particularly, the antibody or antigen-binding fragments thereof or antibody drug conjugate may be administered to a subject suspected of having glioblastoma multiforme (GBM). Subjects in need also encompass those having or suspected of having carcinomas, such as those from breast, head and neck or oral origin,

The term "treatment" for purposes of this disclosure refers to both therapeutic treatment and prophylactic or preventative measures, wherein the object is slow down (lessen) the targeted pathologic condition or disorder. Those in need of treatment include those already with the disorder as well as those prone to have the disorder or those in whom the disorder is to be prevented. Particularly, subjects in need include subjects with an elevated level of one or more cancer markers.

Alternatively, in order to carry out the methods of the present disclosure and as known in the art, the antibody or antigen-binding fragment of the present disclosure (conjugated or not) may be used in combination with a second molecule (e.g., a secondary antibody, etc.) which is able to specifically bind to the antibody or antigen-binding fragment of the present disclosure and which may carry a desirable detectable, diagnostic or therapeutic moiety.

The antibody or antigen-binding fragment thereof of the present disclosure may be used in an unconjugated form or conjugated with a detectable moiety in assays or methods involving detection of EGFRvlll.

Methods of treating subject having a cancer associated with EGFRvlll expression are particularly contemplated. Such method may comprise administering an antigen-binding agent disclosed herein or cells expressing such antigen-binding agent.

In an exemplary embodiment, the method may comprise administering an antibody-drug conjugate.

In another exemplary embodiment, the method may comprise administering cells expressing a chimeric antigen receptor, a bi-specific T-cell engager, a bispecific killer cell engager or a trispecific killer cell engager.

Another aspect of the disclosure relates a method for detecting EGFRvlll, the method may comprise contacting a cell expressing EGFRvlll, or a sample (biopsy, a body fluid such as serum, plasma, urine etc.) comprising or suspected of comprising EGFRvlll with the antibody or antigen binding fragments described herein and measuring binding. The sample may originate from a mammal (e.g., a human) which may have cancer (e.g., glioblastoma multiforme or carcinoma) or may be suspected of having such cancer. The sample may be a tissue sample obtained from the mammal or a cell culture supernatant.

In accordance with the disclosure the sample may be a serum sample, a plasma sample, a blood sample or ascitic fluid obtained from the mammal.

Further scope, applicability and advantages of the present disclosure will become apparent from the non-restrictive detailed description given hereinafter. It should be understood, however, that this detailed description, while indicating exemplary embodiments of the disclosure, is given by way of example only, with reference to the accompanying drawings.

EXAMPLES

Example 1 : Generation of EGFRvlll specific monoclonal antibodies

Monoclonal antibodies (mAb) against EGFRvlll were generated by immunizing mice with the extracellular domain of recombinant proteins.

Immunizations

Mice were bled (pre-immune serum) and injected intraperitoneally and subcutaneously with 100 pg of recombinant EGFRvlll protein emulsified in TITERMAX™ adjuvant (Cedarlane Labs, Burlington, ON) at day 0 and in PBS without adjuvant at day 22. Blood was collected in

microvette CB 300Z (Sarstedt, Montreal, QC) at day 29, and serum was stored at -20°C until further use.


Pre- and post-immune sera titers of animals were assessed by ELISA on recombinant EGFRvlll protein. Unless otherwise stated, all incubations were performed at room temperature. Briefly, half-area 96-well plates (Costar #3690) were coated with 25 pi per well of immunogen at 5 pg/ml in PBS and incubated overnight at 4°C. Microplates were washed three times in PBS and blocked for 30 min with PBS containing 1 % bovine serum albumin (BSA, Sigma Cat#A7030). Blocking buffer was removed and 25 mI of serial dilutions of sera samples were added. After a 2- h incubation, microplates were washed 4 times with PBS-TWEEN™ 20 0,05% and 25 mI of a 1/5,000 dilution of alkaline phosphatase conjugated F(ab’)2 goat anti-mouse IgG (H+L, #1 15-056- 062, Jackson Immunoresearch, Cedarlane, Burlington, ON) in blocking buffer was added. After a 1-h incubation, microplates were washed 4 times and 25 mI of p-nitrophenyl phosphate (pNPP) substrate (Sigma-Aldrich Canada Co., Oakville, ON) at 1 mg/ml in carbonate buffer at pH 9.6 was added and further incubated for 30 min. Absorbance was read at 405 nm using a SpectraMax 340 PC plate reader (Molecular Devices, Sunnyvale, CA). All pre-immune bleeds were negative and all post-immune bleeds were very strong (titer above 1/51200) on recombinant protein.


Mice received a final boost of 100 pg of recombinant EGFRvlll protein and their spleen was harvested 3 to 4 days later. All manipulations were done under sterile conditions. Spleen cells were harvested in Iscove’s Modified Dulbecco’s medium (IMDM, Gibco Cat. #31980-030) and fused to NS0 myeloma cell line using electrofusion protocol.

Spleen cells and myeloma cells were washed separately in IMDM. Cells were washed in Isoosmolar buffer (Eppendorf cat#4308070536), then in Cytofusion Medium C (BTX cat#47- 0001 ). Myeloma and lymphocytes were mixed together at a 1 :1 ratio and fused using an ECM 2001 Cell Fusion System (BTX, Harvard Bioscience Inc.) following manufacturer’s instructions.

Following fusion, cells were suspended at a concentration of 2-4X105 input myeloma cells per ml in HAT selection medium (IMDM containing 20% heat inactivated FBS, penicillin- streptomycin (Sigma Cat#P7539), 1 ng/ml mouse IL-6 (Biolegend Cat#575706), HAT media supplement (Sigma Cat#H0262) and L-glutamine (Hy-Clone Cat#SH30034.01 ) and incubated at 37°C, 5% CO2. The next day, hybridoma cells were washed and suspended at a concentration of 2-5X105 input myeloma cells per ml in semi-solid medium D (StemCell Technologies Cat.#03804) supplemented with 5% heat inactivated FBS, 1 ng/ml mouse IL-6 and 10 pg/ml FITC- F(ab’)2 Goat anti-mouse IgG Fc gamma specific (Jackson # 1 15-096-071 ). The cell mixture was plated in Omnitray dish (Nunc cat#24281 1 ) and further incubated for 6-7 days at 37°C, 5% CO2. Fluorescent secretor clones were then transferred using a mammalian cell clone picker (ClonepixFL™, Molecular Devices) into sterile 96-w plates (Costar #3595) containing 200 pi of IMDM supplemented with 20% heat inactivated FBS, penicillin-streptomycin, 1 ng/ml mouse IL-6, HT media supplement (Sigma Cat# H0137) and L-glutamine and incubated for 2-3 days at 37°C, 5% C02.

Five thousand (5000) hybridoma supernatants from seven (7) fusion experiments were screened by ELISA using recombinant EGFRvlll or EGFR wild type proteins to detect specific binders. To this end, half-area 96-well plates (Costar #3690) were coated with 25 mI per well of immunogen at 5 pg/ml in PBS and incubated overnight at 4°C. Microplates were washed three times in PBS and blocked for 30 min with PBS containing 1 % bovine serum albumin (BSA, Sigma Cat#A7030). Blocking buffer was removed and 25 pi of hybridoma supernatant were added. After a 2-h incubation, microplates were washed 4 times with PBS-TWEEN™ 20 0,05% and 25 pi of a 1/5,000 dilution of alkaline phosphatase conjugated F(ab’)2 goat anti-mouse IgG (Fc specific, #1 15-056-071 , Jackson Immunoresearch, Cedarlane, Burlington, ON) in blocking buffer was added. After a 1-h incubation, microplates were washed 4 times and 25 pi of p-nitrophenyl phosphate (pNPP) substrate (Sigma-Aldrich Canada Co., Oakville, ON) at 1 mg/ml in carbonate buffer at pH 9.6 was added and further incubated for one hour at 37°C. Absorbance was read at 405 nm using a SpectraMax 340 PC plate reader (Molecular Devices, Sunnyvale, CA).

ELISA positive antibodies were selected and further characterized by flow cytometry on U87MG cells overexpressing wt EGFR or EGFRvlll to confirm their specificity. To this end, 15-ml supernatant from each positive clone was produced.

Example 2: Cell surface binding by flow cytometry

The binding properties of the anti-EGFRvlll monoclonal antibodies selected in Example 1 were assessed by flow cytometry on human glioblastoma cell lines U87MG overexpressing wild-type EGFR (U87MG-EGFR wt or U87 WT) and U87MG overexpressing EGFRvlll mutation (D2-7 deletion mutation of EGFR; U87MG-EGFRvlll or U87vlll).

Briefly, cells overexpressing full length wt EGFR or EGFRvlll were obtained from the laboratory of W. Cavanee (Ludwig Institute for Cancer Research, University of California at San Diego). Cells were grown in DMEM high glucose medium containing 10% FBS and 400 pg/ml

G418. Prior to analysis, cells were plated such that they were not more than 80% confluent on the day of analysis, washed in PBS and harvested by the addition of cell dissociation buffer (Sigma). After centrifugation, cells were resuspended in complete medium at a cell density of 2x106 cells/mL Fifty pL/well of cells are distributed in a polypropylene v-bottom 96 well plate and equal volume of hybridoma supernatant were added and incubated for 2 hours. Cells were washed twice by centrifugation and further incubated with a FITC labeled F(ab’)2 goat anti-mouse antibody (Fc specific, #1 15-096-071 , Jackson Immunoresearch, Cedarlane, Burlington, ON) for an hour. Cells were washed and resuspended in medium containing propidium iodide to exclude dead cells from analysis. Samples were filtered through a 60 pm nylon mesh filter plate (Millipore, Ireland) to remove cell aggregates. Flow cytometry analyses were performed on 2,000 viable single-cells events gated on forward scattering, side scattering parameters and propidium iodide dye exclusion using a BD-LSRFortessa flow cytometer (Becton-Dickinson Biosciences, CA, USA) and a standard filter set using BD FACSDiva™ acquisition software, according to manufacturer’s instructions.

Cells were stained with either negative control anti-GFP 3E6 mAb supernatant (open histograms) or tested hybridoma supernatant (grey histograms). Specific binding was reflected by the increase in the mean fluorescent intensity of antibody binding to U87cells expressing EGFRvlll but not wt EGFR.

Out of the 36 positive cell based binding antibodies derived from 7 independent fusion experiments, we chose to further study nine hybridoma supernatants, whose binding was found to be specific for EGFRvlll overexpressing U87MG cells, including 5G6 (Fig. 1A), 1A8 (Fig. 1 B), 4B3 (Fig. 1 C), 4E1 1 (Fig. 1 D), 5D8 (Fig. 1 E), 9C9 (Fig. 1 F), 1 1 B1 (Fig. 1 G), 1 1 C8 (Fig. 1 H) and 1 1 H3 (Fig. 1 1). We used the 225 mAb (ATCC HB-8508) which is a positive control mAb that can bind to both EGFR WT and vlll as shown in Fig. 1 J. The 13.1 .2 antibody was generated and used as a positive control recombinant mAb that binds specifically to vlll isoform, as shown in Fig. 1 K.

Example 3: Evaluation of binding on purified denatured antigen

To evaluate if monoclonal antibodies bind to a conformational epitope, an ELISA analysis on native and denatured recombinant human wild type EGFR and EGFRvlll proteins were performed. The 13.1.2 antibody which is specific to the EGFRvlll mutation (Hamblett K.J, et al., 2015, US Pat. No. 7,736,644) and the 225 antibody, a murine mAb which recognizes both wt EGFR and EGFRvlll were used as controls (Mendelson J et al., 2015, US Pat. No. 4,943,533, Sato J.D. et al., 1983).

Antigens at 1-2 mg/ml were incubated at 95°C for 5 min in PBS containing DTT at a final concentration of 40 mM. They were then incubated on ice for 5 min and diluted at theirfinal coating concentration for ELISA purpose.

mAbs were purified using HiTrap ProteinG HP 1 mL columns GE Healthcare cat no. 17-0404-01 and desalted using Zeba-spin desalting columns 5mL (Pierce) pre-equilibrated in PBS and filter sterilized through 0.22 mM membrane (Millipore). The final concentration of the antibody solutions was determined using a Nano-drop 2000 (ThermoScientific), using IgG as sample type. ELISA was performed as described above (serum titer determination) using 25 mI of mAb supernatant (Exp 1 ) or purified mAb at 1 pg/ml (Exp 2).

Table 1 shows ELISA results (n=2) of different mAb clones assessed on recombinant

EGFRvlll or wt EGFR, in native or denatured conditions. As expected, the 225 antibody binds to both wt EGFR and EGFRvlll under native conditions only. The 13.1.2 antibody binds to EGFRvlll in native and denatured conformation, but not to EGFR wild type native or denatured. The monoclonal antibodies generated by our immunization schemes bind to EGFRvlll in native and denatured conformations. Notably, a few of our anti-EGFRvlll monoclonal antibodies (4B3, 4E1 1 , 5D8 and 9C9) were positive on wt EGFR native antigen although these were not binding to U87MG overexpressing wt EGFR as demonstrated in Example 2.

Table 1. Binding on native or denatured recombinant proteins by ELISA



ND: not determined

Example 4: Assessment of anti-EGFRvlll mAb for internalization

The purified anti-EGFRvlll monoclonal antibodies were evaluated for their ability to internalize into EGFRvlll expressing cells using a surrogate assay in which anti-mouse Fc secondary antibodies are coupled to the pHrodo dyes (Thermo Fisher Scientific). These pH-sensitive dyes can be used to specifically detect endocytosis in live cells due to their enhanced fluorescence in the low pH environment of endosomes and lysosomes.

To that effect, glioblastoma U87-MG cells overexpressing human EGFR WT or vlll mutation were used. Generally, cells were passaged once or twice a week and used within 4-6 weeks for all experiments. U87MG cells were seeded in 96-well plates (Corning 3721 ) at a density of 12,500 cells/well in 100 pi of culture medium. The next day primary mouse antibodies (anti-EGFRvlll monoclonal antibodies) at 20 nM were pre-incubated for 30 min with 30 nM of anti mouse secondary antibody chemically conjugated with pHrodo Red (Thermofisher Scientific), a pH-sensitive dye that is almost non-fluorescent at neutral pH and fluoresces brightly in acidic environments as it is internalized. Cell culture medium was replaced with 50 mI of fresh medium and 50 mI of the antibody complex was added to the cells and their fluorescence was measured after 24-h incubation at 37°C, 5% CO2. Incubation with no primary antibody (secondary antibody alone) or an irrelevant primary antibody (control mouse IgG or anti-GFP mAb) was used to assess non-target internalization. Microplate was read at Exc560nm/Em590nm (5 nm bandwidths) and data were blank subtracted.

Table 2 shows the results of the surrogate antibody internalization of anti-EGFRvlll monoclonal antibodies on EGFRvlll- or wild type EGFR-overexpressing U87MG cells. Results are expressed as the percentage of relative fluorescence unit (RFU) compared to the 225 antibody positive control (a wild type EGFR internalizing mAb that can bind to both wt EGFR and EGFRvlll antigens) calculated according to Formula I:

% internalization = RFU test mAb / RFU 225 mAb X 100 (Formula I)

The selected panel of mAbs showed significant internalization when incubated with EGFRvlll-overexpressing U87MG cells and no internalization in wt EGFR-overexpressing cells.


a This mAb was assessed at 1 nM final concentration

Anti-EGFRvlll monoclonal antibodies showing internalization potency in secondary conjugate pHrodo-based internalization screening in EGFRvlll overexpressing cells but not in EGFR-WT were selected for further analysis.

Example 5: Functional characterization for antibody drug conjugate (ADC) potential.

The purified anti-EGFRvlll monoclonal antibodies were evaluated for their ability to cause growth inhibition in EGFRvlll expressing cells using a surrogate assay in which anti-mouse Fc secondary antibodies were coupled to the DM1 maytansine drug through a non-cleavable linker. Once internalized, linker catabolism in the lysosome releases active DM1 drug which destabilizes microtubules and causes growth inhibition. U87MG glioblastoma cell lines overexpressing wt EGFR or EGFRvlll were used. Generally, cells were passaged once or twice a week and used within 4-6 weeks for all experiments.

U87MG cells (EGFR WT or EGFRvlll) were seeded the day before at 2,000 cells/100pL/well in 96-well plates (Corning 3917). Primary mouse antibodies (anti-EGFRvlll monoclonal antibodies) at 1 nM were pre-incubated for 30 min with 1.5 nM of anti-mouse

secondary antibodies chemically conjugated with Maytansine (DM1 ), a tubulin inhibitor that needs to be internalized to cause cell death. The antibody complex was then added to the cells indicated and their effects on cell viability measured after 5 days of incubation at 37°C. Incubation with no primary antibody (secondary antibody alone) or an irrelevant primary antibody (control mouse IgG or 3E6 anti-GFP mAb) was used to assess non-target-directed cytotoxicity. Cell viability was determined using CellTiterGlo™ (Promega, Madison), based on quantitation of the ATP present in each well, which signals the presence of metabolically active cells. Signal output was measured on a luminescence plate reader (Envision, Perkin Elmer) set at an integration time of 0.1 sec. Integration time is adjusted to minimize signal saturation at high ATP concentration.

Data expressed as Relative Luminescence Unit (RLU) is normalized to the mouse IgG control wells and expressed as % survival compared to mouse IgG, calculated according to Formula II:

% survival = RLU mAb / RLU mouse IgG X 100 (Formula II)

mAbs were selected that show high potency in secondary conjugate DM1 -based cytotoxicity screening in EGFRvlll overexpressing cells but not in EGFR-WT.

Table 3 shows results of the ADC surrogate screening assay of anti-EGFRvlll monoclonal antibodies on EGFRvlll or wt EGFR -overexpressing U87MG cells. Results are expressed as the percentage of survival relative to that of non-specific mouse IgG control (set at 100%). The antibodies tested were shown to cause a significant reduction in survival (>15%) in EGFRvlll overexpressing cells relative to EGFR wild type overexpressing cells. As expected, the 225 antibody positive control causes cytotoxicity in both cell lines.



The degree of cytotoxicity associated with these antibodies selected from among 36 primary mouse mAbs tested, demonstrates that they exhibit a high degree of internalization and appropriate intracellular routing to achieve activation of the DM1 or MMAE drug, making them suitable for ADC development. Thus, mAbs that exhibited cytotoxicity in a surrogate ADC assay were selected for direct conjugation to DM1 or MMAE.

Selected hybridoma were recloned by limiting dilution to ensure their monoclonality.

Example 6: DM1 conjugation and ADC testing of mouse monoclonal mAbs

The anti-EGFRvlll monoclonal antibodies purified in Example 3 were conjugated via lysine residues to succinimidyl trans-4-[maleimidylmethyl] cyclohexane-1 -carboxylate (SMCC) linked to N2’-deacetyl-N2’-(3-mercapto-1-oxopropyl)-maytansine (DM1 ) or via reduced interchain Cysteine residues to a cathepsin cleavable linker (valine-citrulline) Monomethyl auristatin E (MMAE). Product purity and drug:antibody ratio were determined by UPLC based size-exclusion chromatography (SEC).

For conjugation, the purified anti-EGFRvlll monoclonal antibodies (5G6 1A8, 4B3, 4E11 , 5D8, 9C9, 1 1 B1 , 1 1C8, 11 H3; Example 3) were buffer-exchanged into conjugation buffer (100 mM Sodium phophate, 20 mM NaCI, 2 mM EDTA pH 7.2) using pre-equilibrated spin desalting columns. The concentration of each monoclonal antibody was adjusted to 2 mg/mL with conjugation buffer and 200 pg total of each was used for conjugation. A stock solution of SMCC-DM1 was prepared in dimethylacetamide (DMA). SMCC-DM1 from the DMA stock solution was added to each monoclonal antibody to achieve a molar SMCC-DM1 :mAb ratio of 10.0. The solution was mixed thoroughly and incubated at 37°C for 3 hours. The reaction was stopped by passing the reaction mixture through two spin desalting columns equilibrated in Conjugation buffer with 0.02% w/v Polysorbate-20 added.

ADCs were selected for an appropriate drug-antibody ratio (DAR) range (generally between 3 and 5 drugs/antibody) and monomeric purity (>95% monomer content using analytical SEC). DAR was determined by integrating the monomeric peak from the UPLC-SEC chromatogram at both 280 nm and 252 nm and comparing these to the ratios of extinction coefficients for the unconjugated antibody and free drug at the same wavelengths. Percent monomer was determined from the total integrated areas of monomer, high-molecular weight species and low-molecular weight species observed in the chromatogram. In vitro growth inhibition potency results for these DM-1 conjugated ADCs are shown in Table 4. Specifically, anti-EGFRvlll ADCs prepared above were tested for their effects on viability of U87MG overexpressing EGFR WT or EGFRvlll cells. Following 5 days of exposure, cell growth/viability was assessed using CellTiterGlo reagent and dose-response curves were generated to measure their potency (IC50) and efficacy (% maximal inhibition) using the log(inhibitor) vs. response --Variable slope (four parameters) model from GraphPad Prism v6.0 software.

All the DM1 -conjugated anti-EGFRvlll antibodies tested demonstrated good efficacy (from 76-97% maximal growth inhibition) and strong potency (IC50 < 0.37-4.1 nM) on EGFRvlll expressing U87MG cells as compared to the non-targeted irrelevant anti-GFP mouse lgG-DM1 conjugate negative control (Table 4). Furthermore, this effect was specific for EGFRvlll-expressing cells, since activity seen in the EGFRwt U87MG expressing cells (IC50 range =15-30 nM) was not significantly different than that seen for the irrelevant ADC control (IC50~25nM).

Table 4 provides the results of ADC testing of mAbs anti-EGFRvlll % max inh = percent maximal inhibition.



Example 7: Evaluation of apparent affinity by flow cytometry.

Purified anti-EGFRvlll monoclonal antibodies were assessed for their binding activity by flow cytometry in a dose-dependent binding curve using U87MG glioblastoma cell line overexpressing vlll or wt EGFR.

Prior to analysis, cells were plated such that they were not more than 80% confluent on the day of analysis. Unless otherwise stated, all media are kept are 4°C and all incubations are performed on wet ice. Cells were washed in PBS, harvested by the addition of cell dissociation buffer (Sigma), centrifuged and resuspended in complete medium at a cell density of 2x106 cells/mL. Fifty pL/well of cells were distributed in a polypropylene v-bottom 96 well plate and serial 1/3 dilutions of purified mAbs starting at 100 nM were added and incubated for 2 hours. Cells were washed twice by centrifugation and further incubated with a FITC labeled F(ab’)2 goat anti mouse antibody (Fc specific, #115-096-071 , Jackson Immunoresearch, Cedarlane, Burlington, ON) for an hour. Cells were washed and re-suspended in medium containing Propidium iodide to exclude dead cells from analysis. Samples were filtered through a 60 pm nylon mesh filter plate (Millipore, Ireland) to remove cell aggregates. Flow cytometry analyses were performed on 2,000 viable single-cells events gated on forward scattering, side scattering parameters and propidium iodide dye exclusion using a BD-LSRFortessa flow cytometer (Becton-Dickinson Biosciences, CA, USA) and a standard filter set using BD FACSDiva™ acquisition software, according to manufacturer’s instructions.

Specific detection of antibody binding was calculated as the mean fluorescent intensity of binding to each primary antibody after background level subtraction of the mean fluorescent intensity of binding of mouse IgG control. The data were analyzed with GraphPad Prism v 6.0 software using one-site specific binding with Hill slope non-linear regression curve fit model to determine Bmax (maximum specific binding) and Kdapp (concentration needed to achieve a half-maximum binding at equilibrium) for each mAb tested. The model used was according to formula III:

Y=Bmax*Xh /(Kdh + Xh) (formula III)

Bmax is the maximum specific binding, in the same unit as Y.

Kd is the ligand concentration needed to achieve half maximum binding at equilibrium, expressed in the same unit as X.

The variable“h” is the hill slope.

Figure 2 shows results of flow cytometry experiments determining the binding properties of anti-EGFRvlll monoclonal antibodies to cell surface-expressed EGFRvlll (Fig. 2A and 2C) or wt EGFR (Fig. 2B and 2D). The 225 is a mouse mAb that binds to both wild type and vlll mutant EGFR and is used as a positive control for both cell lines. All anti-EGFRvlll mAbs showed strong and comparable binding to cells overexpressing EGFRvlll variant (Fig. 2A and 2C) and no detectable binding (ndb) on cells overexpressing wild type EGFR (Fig. 2B and 2D). Except for 9C9 (data not shown), all monoclonal antibodies bind with low nM affinity to cells overexpressing EGFR vlll variant in flow cytometry analysis (Table 5).

Table 5: Apparent KD of anti-EGFR vlll mAbs as determined by Flow cytometry analysis.


Example 8. Epitope binning by Flow cytometry competition.

In order to evaluate whether anti-EGFRvlll monoclonal antibodies bind to the same epitope region, flow cytometry competition experiments on U87MG-vlll cells were performed.

To that effect, the purified monoclonal antibodies 4E11 and 13.1.2 were conjugated to AlexaFluor 488 fluorescent dye (Thermofisher, Burlington, ON, Canada) using a NHS Ester derivative, according to manufacturer’s instructions.

A fixed concentration of the labeled mAb (1-10 nM) was incubated with increasing concentration (or 10X concentration) of our unlabeled monoclonal antibodies to assess if their binding capacity was impaired in presence of unlabeled mAbs.

From the results shown in Table 6, it can be seen that the selected anti-EGFRvlll monoclonal antibodies fall into 2 major epitope regions categorized by binding of 2 prototypic antibodies; 1 ) bin 1 antibodies were found to compete with labeled 13.1.2 including antibodies 5G6, 1A8, 1 1 B1 , 1 1C8 and 11 H3 and 2) bin2 antibodies were found to compete with labeled 4E11 antibodies including antibodies 4B3 and 5D8. The affinity of antibody 9C9 being lower, it did not compete with any of the labeled mAbs in this experiment.

Table 6. Competition Assay by flow cytometry


“NC” = no competition;“SC” = self-competition;“C” = competition;“ND” = not determined.

Example 9. Epitope mapping by yeast surface display

The yeast surface display method (Feldhaus MJ et ai, 2003 Nat Biotechnol. 2003 Feb; 21 (2):163-70) was used to map the epitopes of our anti-EGFRvlll monoclonal antibodies. This technique allows cloned protein or peptide of choice to be expressed and displayed at the cell surface through covalent linkage to cell wall. The displayed protein/peptide can be interrogated for antibody binding.

A total of 36 different hEGFRvlll fragments of variable size from 10 to 414 amino acid residues were cloned into the pPNL6 vector (obtained from The Pacific Northwest National Laboratory, USA) as fusion proteins to be expressed and displayed as Aga2-HA-hEGFRvlll-MYC. The displayed hEGFRvlll fragments were used to identify the smallest fragment required for the binding of each anti-hEGFRvlll mAbs.

Assessment of the binding of anti-EGFRvlll mAbs to the fusion proteins expressed on yeast cell surface was done by flow cytometry analysis. Briefly, yeast cells were labeled with both the anti-hEGFRvlll mAb and chicken anti-Myc antibody, the latter being used to monitor the level of expression of the fusion protein. Following a wash step, binding of the primary antibodies is probed by a two-color indirect fluorescence labeling using secondary antibodies specific for mouse and chicken antibodies, respectively.

The anti-hEGFRvlll mAbs were binding with similar signal intensities to both full length hEGFRvlll protein and small peptides of the same protein, as well to both native and heat denatured yeast displayed antigen fragments, suggesting that the epitopes for these mAbs are contained within a continuous peptide fragment (linear).

Figures 4A and 4B show the results of anti-hEGFRvlll monoclonal antibodies binding properties to various fragments of the hEGFRvlll and wt EGFR protein displayed on yeast cells.

Table 7 shows the smallest fragment (peptide) required for respective anti-hEGFRvlll mAbs binding. Four different epitope bins were identified: 1 ) aa 1-18 recognized by 11 B1 , 1 1C8 (H5) and 11 H3 as well as the 13.1.2 control mAb, 2) aa 3-18 recognized by 5G6 and 1A8, 3) aa 15-37 recognized by 4B3, 5D8 and 9C9, and 4) aa 19-37 recognized by 4E11. Despite the absence of binding on U87MG-EGFR WT expressing cells, 4E1 1 did bind to yeast cells engineered to express EGFR WT fragments 266-482 and 1-623 (Figures 4A and 4B).


Example 10. Fine epitope using yeast surface display

To further characterize mAb epitopes within the EGFRvlll 15-37 region, an alanine scan of this region was performed, and modified fragments were expressed at the surface of the yeast. All of the amino acids of SEQ ID NO.:6 were mutated to alanine, except for amino acid residues 5 and 8 which correspond to the original Ala19 and Ala22 of EGFRvlll. The resulting peptides were expressed at the surface of the yeast and each anti-EGFRvlll mAbs was tested on the corresponding yeast mutant strain by flow cytometry analysis. Thus, this assay determined the contribution of each amino acid(s) in the monoclonal antibody binding. Table 8 shows the results obtained in flow cytometry analysis for the 4B3, 5D8, 9C9 and 4E11 monoclonal antibodies. Results obtained are in line with the previous results shown in Table 7, i.e. binding of mAbs in bin 15-37 are strongly inhibited by mutation of one AA between position 15 and 19.

Both mAbs 4B3 and 5D8 binding is abolished by mutation of either amino acid residues Arg18, Cys20, Gly21 or Cys35, and weakened by mutation of Gly31 to Alanine. mAb 5D8 binding is weakened by mutation of Glu26 to Alanine. 9C9 binding is compromised by mutation of either Cys16, Glu26, Gly31 , Val32, Arg33, Lys34, Cys35 or Lys36, and weakened by Cys20 or Asp30 mutation to Alanine. 4E11 binding is strongly inhibited by mutation of either Cys20, Glu26, Asp30, Gly31 , Arg33 or Cys35, and weakened by Asp23 or Val32 mutation to Alanine. Based on these results, amino acid residues Cys20 and Cys35 appear important for binding of antibodies

targeting amino acid residues 15-37 of EGFRvlll.

Table 8. Flow cytometry evaluation of mAb binding to yeast expressing mutated amino acid within fragment 15-37 of EGFRvlll. Data represent the % of binding of mAb on the yeast displaying the mutated sequence compared to the binding on the yeast displaying the wild-type sequence, normalized to the Myc-tag expression.


*Original Ala 19 and Ala 22 were not mutated

Legend

Values between 0% and 15%: No binding

Values between 16% and 59%: Partial binding

Values at or above 60%: Complete binding

Example 11 : Antibody sequencing

The sequences of the VH and VL domains of thirteen anti-EGFRvlll monoclonal antibodies of Examples 2-5 were analyzed.

Briefly, total RNA was extracted from hybridoma clones (Qiagen, RNEasy) and reverse transcribed into cDNA (SuperScriptTM, ThermoFisher Scientific, Waltham, MA, USA). DNA encoding VH and VL domains was PCR amplified (Platinum Taq or equivalent) using mixtures of degenerate forward primers annealing in FR1 and a single reverse primer annealing in CH1 (Novagen/EMD Millipore cat. no 69831-3). The resulting amplicons were sequenced using the Sanger method on an ABI 3730x1 instrument or were determined using 2x250 bp reads on an lllumina MiSeq instrument.

Sequences of the VH and VL domains as well as the CDR regions are shown in the sequence table. The CDRs are generally indicated in bold in the light chain or heavy chain variable regions amino acid sequences. Analysis of the sequence for a consensus binding sequence of the CDR 1-3 regions of the VH and VL chains was conducted using Kabat numbering scheme (Kabat et L 1992, Johnson et al 2004). The results indicated that the CDR regions of both the VH and VL regions of the 1 1 B1 , 11 C8 and 1 1 H3 monoclonal antibodies are identical. There is one amino acid difference in VH between 11 B1 and 1 1C8 (FR2 region), one amino acid difference in VH between 1 1 C8 and 11 H3 (FR3 region), and 2 amino acid difference between 11 B1 and 1 1 H3 (FR2 and FR3). These antibodies clustered together and recognize a common linear epitope within fragment 1-18 (Table 7).

An alignment between 1 1 B1 (SEQ ID NO:77), 1 1C8 (SEQ ID NO:92) and 11 H3 (SEQ ID NO:102) heavy chain variable regions is presented in Figure 5A. The consensus obtained from this alignment is provided in SEQ ID NO:1 17. The 11 B1 (SEQ ID NO:67), 11 C8 (SEQ ID NO:82) and 1 1 H3 (SEQ ID NO:97) light chains are identical.

4B3 and 5D8 have identical VL CDRs, with 2 amino acid differences in FR1 and one amino acid difference in FR4. They have similar VH CDRs, with one amino acid difference in CDRH1 , one amino acid difference in CDRH2 and one amino acid difference in each of FR1 and FR3. They both bind to the same epitope on EGFRvlll as shown in Table 8.

An alignment between the 4B3 (SEQ ID NO:27) and 5D8 (SEQ ID NO:47) light chain variable regions is provided in Figure 5B. The consensus obtained from this alignment is provided in SEQ ID NO:1 15. An alignment between the 4B3 (SEQ ID NO:32) and 5D8 (SEQ ID NO:52) heavy chain variable regions is provided in Figure 5C. The consensus obtained from this alignment is provided in SEQ ID NO:1 16.

9C9 has VL similar to that of 4B3 and 5D8 (one amino acid difference in CDRH1 and four others in FR3 and FR4) and a unique VH, and binds to a unique epitope (Table 8).

An alignment between 4B3 (SEQ ID NO:27), 5D8 (SEQ ID NO:47) and 9C9 (SEQ ID NO:57) light chain variable regions is presented in Figure 5D. The consensus obtained from this alignment is provided in SEQ ID NO:1 18.

The sequence analysis also revealed that clone 1 1 B1 expresses two light chains; one which is dominant (variable region illustrated by SEQ ID NO:67) and a low abundant transcript (SEQ ID NO:72). Similarly, clone 1 1 C8 expresses two light chains; a dominant (SEQ ID NO:82) and a low abundant transcript (SEQ ID NO:87). Clones 1 1 G8 and 1 1 H5 also expresses these two transcripts (data not shown).

The sequence analysis revealed that clones 5G6, 1 A8 and 4E1 1 have unique VH and VL

CDRs.

Example 12: Recombinant antibody production and purification

To facilitate large scale antibody productions and consistency between productions, the anti-EGFRvlll monoclonal antibodies identified in Example 1 1 were produced recombinantly in CHO cells.

The VH and VL regions were cloned as fusions with human lgG1 constant regions (human lgG1 heavy chain and human kappa light chain, respectively) into the pTT5 vector, thereby generating chimeric antibodies.

The amino acid sequences of the chimeric antibodies: hFC-5G6, hFC-4E1 1 , and hFC-13.1.2 is provided in the sequence table. All light chain sequences comprise a signal sequence MVLQTQVFISLLLWISGAYG (SEQ ID NO:1 13) at the N-terminus, while heavy chain sequences comprised the signal sequence MDWTWRILFLVAAATGTHA (SEQ ID NO:1 14) at the N-terminus.

Chimeric antibody expression was validated via a 2 mL expression scout. Briefly, CHO cells were transiently transfected with VL and VH containing constructs (1 :1 ratio); conditioned medium (CM) was harvested on day 7, and chimeric antibody expression levels were evaluated

by SDS-PAGE (data not shown). The chimeric antibody expressed well and a small-scale production (50 mL) was initiated by transiently transfecting CHO cells with the same construct ratio. Conditioned medium (CM) was harvested on day 7, chimeric antibodies were purified (ProtA), quantitated, and evaluated by SDS-PAGE. The data showed that all four chimeric antibodies were well expressed by the transiently transfected CHO cells.

To confirm that the recombinantly expressed chimeric antibodies behave similarly to the hybridoma-expressed monoclonal antibodies, flow cytometry binding experiments on U87MG overexpressing EGFRvlll were performed to ensure that EGFRvlll binding was not compromised. Furthermore, binding and ADC activity were also tested using a glioblastoma cell line that overexpresses EGFRvlll that was obtained from Cellther Polska (catalogue number CL 01008-CLTH). These cells were grown in RPMI and 10% fetal bovine serum using standard culturing conditions.

Evaluation of apparent affinity was performed by flow cytometry analysis as described in Example 7, except that a secondary AF488 labeled F(ab’)2 donkey anti-human antibody (Fc specific, #709-546-098 Jackson Immunoresearch, Cedarlane, Burlington, ON) was used to detect the primary antibody binding.

All chimeric antibodies bind with specificity and with similar affinity to glioblastoma cells overexpressing EGFRvlll mutation in flow cytometry analysis (Table 9). Importantly, all chimeric antibodies (including the benchmark 13.1.2) fail to bind wt EGFR as seen by the lack of cell surface binding on U87 cells overexpressing wtEGFR. This specificity is unlike that seen with ABT-806 which has been shown to bind significantly to U87MG EGFRwt cells (Panousis et al 2005) and which may account for toxicity due to wt EGFR expression on normal tissues.

Table 9. Cell binding on EGFRvlll expressing glioblastoma cells


Example 13: DM1 and MMAE conjugation of recombinantly expressed chimeric mAbs and ADC testing

Chimeric antibodies produced in Example 12 were conjugated with DM1 or MMAE and tested on glioblastoma cells overexpressing wt EGFR or EGFRvlll protein as described in Example 6. Conjugation of antibodies to the reduced interchain cysteines of EGFRvlll or control mAbs to monomethylauristatin E (MMAE) drug attached to a peptide cleavable valine-citrulline linker was done using the following methodology. Lyophilized MC-vc-PAB-MMAE is solubilized in dimethylacetamide to a final concentration of 10 mM. This stock is aliquoted and stored at -20°C until used. Prior to conjugation, each protein sample must have its surface-accessible disulphide bonds reduced to generate reactive free thiols. The level of DAR is controlled by adjusting the degree of reduction of disulphide bonds by increasing the concentration of reducing agent. To achieve the desired specified DAR, a three-point scouting experiment using three different concentrations of TCEP (24, 40 and 55 mM) with a final concentration of antibody of 10 mM. The reduction is initiated by addition of TCEP from a 25X working stock into the antibody solution in the following buffer: 100 mM sodium phosphate, 20 mM NaCI, 2 mM EDTA, pH 7.2. The mixture is incubated at 37°C for 3 h. A 10-fold molar excess (100 pM) of MC-vc-PAB-MMAE is added to the reaction mixture from a 20X working stock in DMA. The final concentration of co-solvent in the reaction is 5% v/v. The reaction is incubated at 25°C for 1 h. During this incubation, 3 x 0 .5 mL 7K MWCO Zeba Spin columns are pre-equilibrated in standard formulation buffer (20 mM Succinate, 0.02% w/v Polysorbate-20, pH 6.0). After the reaction is complete, Polysorbate-20 is added to a final concentration of 0.02% w/v prior to passing the reaction mixture consecutively through the pre-equilibrated Zeba columns. To the eluant, 1/5th volume of 36% Trehalose solution (in formulations buffer) is added. Absorbance measurements of the conjugate at 248 nm and 280 nm are used to calculate the DAR, and the sample measured for monomeric purity by HPLC-Superdex size-exclusion chromatography. The DAR for each of the three TCEP concentrations is plotted vs the DAR and the slope of the linear relationship used to determine the optimal concentration to reach the desired DAR. The above procedure is then repeated using these optimal conditions at the specified scale. Final concentration reported for the conjugate is adjusted to compensate for contribution at 280 nm from attached drug.

Prior to conjugation, an absorbance scan of the protein (antibody) sample (2 pl_) is measured on a Nanodrop 2000 instrument. The ratio of the absorbance at 248/280 nm is determined and used to calculate the extinction coefficient of the antibody to be conjugated at 252 nm (for MCC-DM1 conjugates) or 248 nm (for val-cit MMAE conjugates). This value will be used to determine the drug:antibody ratio (DAR) for the conjugate produced.

Drug (DM1- and MMAE-) conjugated antibodies were tested for growth inhibition activity on glioblastoma cell lines (U87 and/or DKMG) expressing EGFRvlll or wt EGFR. Typical results are shown in Figure 6 and averages presented in Tables 10 and 1 1.

The DM1 -conjugated chimeric anti-EGFRvlll antibodies demonstrated good efficacy (from 77-80% maximal growth inhibition) and strong potency (IC50 range 0.9 -3.9 nM) compared to the benchmark mAb used (hFc13.1.2-DM1 , IC50= 9.3 nM) in the U87 EGFRvlll expressing cell lines analyzed. Furthermore, the activity of both test antibodies, particularly hFc-4E1 1-DM1 , appeared to be very potent on EGFRvlll expressing cells i.e. 18-fold more potent than that seen on EGFRwt expressing cells and 25-fold more potent than that seen with DM1 -conjugated Palivizumab, the non-targeted irrelevant control ADC. (Table 10). Similar results were seen in DKMG cells expressing EGFRvlll.

Table 10 provides the results of DM1-ADC testing of chimeric anti-EGFRvlll antibodies

DAR: drug-antibody ratio

% max inh = percent maximal inhibition.

Table 10: Results of DM1-ADC testing of chimeric anti-EGFRvlll Antibodies


When tested, the MMAE-conjugated chimeric anti-EGFRvlll antibodies demonstrated good efficacy (from 75-95% maximal growth inhibition) and strong potency (IC50 < 0.2-0.4 nM) in cell lines overexpressing EGFRvlll compared to the benchmark 13.1.2 (IC50 of 1.9-2.5) or to the non-targeted irrelevant chimeric Palivizumab conjugate negative control (Table 11 ).

Table 1 1 provides the results of MMAE-ADC testing of chimeric anti-EGFRvlll Antibodies

Notably, both DM1- and MMAE conjugated hFc-4E1 1 and hFc-5G6 show superior functional activity in that they were up to 10 x more potent than the corresponding benchmark 13.1.2 antibody conjugates against cells overexpressing EGFRvlll. In all cases, activity was shown to be significantly greater than that of a non-targeted irrelevant ADC control on cells expressing EGFRvlll. Furthermore, this effect was specific for EGFRvlll-expressing cells, since activity seen in the EGFRwt U87MG expressing cells was not significantly different than that seen for the corresponding irrelevant ADC control.

Example 14: In Vivo Tumor Growth Inhibition by ADCs in U87MG-vlll tumor Xenograft Mouse Models

To further assess efficacy in vivo, anti-EGFRvlll antibody-drug conjugates (ADCs) were evaluated for their ability to inhibit tumor growth in xenograft models expressing EGFRvlll.

The ADCs were tested in glioblastoma subcutaneous xenograft models (study number SP.03: 5 mg/kg of ADC and study number SP.06: 3 mg/kg of ADC).

Briefly, U87MG overexpressing EGFRvlll cells were cultured as described in Example 2. Cells were passaged twice a week and used within 4-6 weeks after thawing. They were harvested by trypsinization (0.25% trypsin/EDTA, Gibcol 5090-046) followed by washing in cold phosphate-buffered saline solution (PBS) and assessed for viability by capacity to exclude trypan blue dye. All cell populations for growth as xenografts in mice were, at a minimum, 98% viable.

Six weeks old, 25 gram male CD1 Albino mice (Crl:CD1-Foxn1nu), were obtained from Charles River Canada (St-Constant, Quebec, Canada). Animals were cared for and used in accordance with the guidelines of the Canadian Council on Animal Care (CCAC).

Cells were subcutaneously inoculated (5x106 cells in a volume of 0.1 mL PBS or HBSS per injection site) in the left flank of isoflurane anesthetized nude mice (n=12) under sterile condition. Tumors were allowed to grow to a size between 80 and 100 mm3 in volume, after which animals were randomized one day prior to the dosing day to ensure that each cohort contains animals with variable tumor sizes.

Tumor growth was monitored every three days by caliper measurement for 29 days post treatment or until they were euthanized for ethical reasons (humane endpoints): 1 ) more than 10% body weight loss without weight recovery within 48 hours; 2) tumor volume over 2500 mm3; 3) tumor ulcerations; 4) clear signs of distress such as immobility and reduced grooming etc.

Tumor volumes were calculated according to Formula IV:

Estimated tumor volume [mm3] = TT/6(length [mm]) c (width [mm] x (height [mm])) (Formula IV)

Test articles were prepared in ADC buffer and shown to contain < 5% aggregates (by HPLC-SEC) and <1 EU/mg endotoxin. Mice were injected intravenously (i.v.) with the test articles at 5 mg/kg (Study SP.03) or 3 mg/kg (Study SP.06) based on DAR3 on day 0 and 4 (96h interval) via tail vein. A control group was treated with ADC buffer.

All animals were observed once daily for mortality and signs of illness. Individual body weight and tumor size of animals were measured and recorded on the day of treatment and every three days afterwards.

Tumor volumes in each group are shown as mean ± SEM and plotted as a function of measurement time after U87MG-EGFRvlll cell inoculation. Group comparisons for the tumor volume data were conducted using two-way ANOVA with T ukey’s multiple comparisons test using GraphPad Prism version 7.0. Differences between treatment and control groups were statistically significant at p < 0.05.

Figure 7 represents the results of Study SP.03 and shows the effect of mouse anti-EGFRvlll ADCs on tumor growth, assessed as tumor volume.

A statistically significant (p<0.05) effect on tumor growth was observed between 5 mg/kg anti-EGFRvlll-DM1 -treated and ADC buffer-treated groups from day 4 to day 20. The average tumor volume growth in the mouse anti-EGFRvlll-treated group was from about 90 to 195-287mm3, compared to the control group, which experienced tumor growth from about 90 to 1620 mm3 at day 20. No statistically significant differences in tumor growth inhibition were observed among the different anti-ADCs at 5mg/kg (Table 12). This striking difference in tumor volume shows that our mouse anti-EGFRvlll ADC can greatly inhibit tumor growth in a glioblastoma tumor model.

Body weight was measured as an indicator of off-target potential toxicity. No significant difference in body weight was observed between the control animals (ADC buffer group) and ADCs treated animals. Mice in both groups gained about 5-10% body weight during the experimental period.

Table 12: Percentage of tumor volume reduction compared to the control groups (ADC buffer). Percentage of tumor volume (TV) reduction compared to control was calculated based on the equation: %=(ATVCOntroi - ATV treated)/ ATVCOntroi * 100; ATV=TVd28 - TVdo


Significant tumor growth inhibition, ranging from 20-50% tumor volume reduction, was also observed in animals treated with 2 mg/kg of mouse anti-EGFRvlll ADCs, including 3E6-DM1 , 11 H3-DM1 , 1A8-DM1 in addition to 5G6-DM1 , 4E1 1-DM1 and the benchmark 13.1.2-DM1 groups as compared to anti-GFP-DM1 irrelevant ADC control (data not shown).

Figure 8A and Figure 8B represent the result of Study SP.06 and show the effect of chimeric anti-EGFRvlll DM1 -ADCs or MMAE-ADCs respectively on tumor growth, assessed as tumor volume. Tumor growth curves in U87MG-EGFRvlll tumor-bearing mice treated twice (day 0 and 4) with either ADC buffer (control) or 3 mg/kg of ADCs, with tumor volumes (mm3) being recorded every three days for 17 days. Each data point represents mean ± SEM, for ADC buffer (circles), hFc-5G6-DM1 (diamonds), hFc-4E1 1-DM1 (open circles), the benchmark hFc-13.1.2-DM1 (triangles) and the negative control Palivizumab-DM1 (squares) groups. Palivizumab is a humanized mAb against respiratory syncytial virus (RSV).

Both Palivizumab-DM1 (Figure 8A) and Palivizumab-MMAE (Figure 8B) treated animals showed a significant decrease (p<0.05) in tumor growth compared to ADC buffer-treated groups with a tumor reduction of 31.0 and 22.8% respectively at day 17 (Table 13). However, the chimeric anti-EGFRvlll ADC-treated animals showed a more significant (p<0.05) reduction in tumor growth compared to buffer-treated groups from day 1 1 to day 17 with a tumor volume reduction between 37.2 to 60.0% at day 17. No statistically significant differences in tumor growth inhibition were observed among the different chimeric anti-EGFRvlll ADCs. There were no statistically significant differences between the corresponding DM1 and MMAE conjugates (p>0.05). U87MGvlll xenografted tumors tended to ulcerate during the experimental period. Both control and ADC-treated groups showed more than 50% ulceration rates, with the only exception of the hFc-4E11-DM1 -treated animals that exhibited a markedly lower ulceration rate (-16.7%, data not shown).

Table 13: Percentage of tumor volume reduction compared to the control groups (ADC buffer) at day 17 post-treatment initiation (Mean ± SEM). Percentage of tumor volume (TV) reduction compared to control was calculated based on the equation: %=(ATVCOntroi - ATV treated)/ ATVcontroi * 100; ATV=TVd17 - TVdo


In summary, the chimeric anti-EGFRvlll ADC-treated animals showed a more significant (p<0.05) reduction in tumor growth compared to buffer-treated groups during the course of the study and were shown to be comparable to or more potent than the 13.1.2 benchmark when evaluated as an MMAE or DM1 conjugate, respectively. Notably, at day 17, the benchmark 13.1.2-DM1 induced a significantly lower tumor growth inhibition in the U87MGvlll model compared to 4E11-DM1 (p<0.05).

Example 15: Chimeric Antigen Receptor T-Cell Functional Testing

Various experiments were performed to demonstrate the activity of novel EGFRvlll-specific single chain variable fragments in the context of a chimeric antigen receptor (CAR). Briefly, single chain variable fragments composed of the heavy and light chains of 5G6 (SEQ ID NO:12 and SEQ ID NO:7 respectively, for example as in the scFv of SEQ ID NO:166) or 4E1 1 (SEQ ID NO: 42 and SEQ ID NO:37 respectively, as provided in for example the scFv of SEQ ID NO:167) sequences linked using a flexible linker sequence and restriction sites (for example, GTGGGGSGGGGSGGGGSDV (SEQ ID NO:171 ), it should be noted that any suitable linker known in the art may be used in the scFv constructs provided herein) were combined with a standard CAR construct. CAR construct used for testing was comprised of one of a human CD28-signal peptide, immediately aforementioned scFv sequences, a mouse CD8-hinge domain, human CD28-transmembrane domain, CD28-intracellular signal transduction domain, and CD3-zeta intracellular signal transduction domain (5G6-CAR SEQ ID NO: 168, 4E1 1 -CAR SEQ ID NO: 169).

The in vitro functionality of the EGFRvlll CAR constructs was tested using a novel flow cytometry based high-throughput screening platform developed by the Applicant; which is in some instances referred to as CAR-J assay. In brief, EGFRvlll-specific (described immediately above) or control (CD19-targeted) CAR plasmids were electroporated into the Jurkat human CD8+ T-cell line. Cells expressing CAR were then exposed to various target cell lines (with or without EGFRvlll expression) in varying doses and maintained under standard culture conditions. Following 24 hours of co-incubation with target cells, CAR-T cells were examined for cellular activation by flow cytometry via surface expression of the T-cell activation marker CD69. The level of auto-activation (tonic signaling) associated with each CAR was also examined by quantification of the level of CD69 expression on non-stimulated CAR-expressing Jurkat cells or CAR-expressing Jurkat cells incubated with irrelevant target cells (Figure 10).

Human primary peripheral blood derived T cells were used for confirmation of in vitro and in vivo activity of EGFRvlll targeted 4E1 1 or 5G6 CARs constructs in the context of primary human immune cells. In brief, EGFRvlll-CAR or control (human CD19-targeted FMC63-CAR) lentivirus was generated using standard production protocols in HEK293 and concentrated using ultracentrifugation. Primary T cells were isolated from donor blood samples using magnetic separation and activated using anti-CD3/CD28 beads. Primary T cells were then transduced with CAR lentivirus and expanded for several days in culture.

In vitro functionality of primary human EGFRvlll-specific CAR-transduced T cells were assessed using a live-fluorescence microscopy approach. Briefly, EGFRvlll targeted CAR-T or mock transduced T cells, wherein no lentiviral construct was introduced into cells handled under similar conditions, were generated as described immediately above. Cells were then placed in co-culture with EGFRvlll-expressing target cells modified to also express a nuclear-localized form of mKate2 fluorescent protein. Co-cultures were monitored constantly over 6 days using the Incucyte™ automated live fluorescent microscopy device (Sartorius, USA). The relative growth of target cells was then assessed using automated counting of mKate2+ cells (Figure 1 1 ). Data showed that the growth of U87MG overexpressing EGFRvlll cells was efficiently repressed by 4E1 1 or 5G6 CAR-T compared to a control CAR-T (FMC63) or mock transduced T-cells.

The in vivo functionality of the EGFRvlll targeted primary CAR-T cells was also tested using Nod-SCID-IL2yR2 / (NSG) mice (Jackson Laboratory, Barr Harbor, ME) bearing EGFRvlll expressing U87vlll tumors. Briefly, mice were subcutaneously injected with 1x106 fluorescently labelled U87-vlll cells. Eight days after tumour cell injection, cryo-preserved CAR-T cells were thawed, washed with PBS, and 1 x107 total T cells (with 20-25% CAR transduction) were immediately delivered intra-tumourally, ensuring equal distribution of tumour sizes between groups. Tumour growth was evaluated three times per week using calipers by trained animal technicians blinded to specific treatment groups (Figure 12A). Primary endpoint was tumour size above 2000 mm3, with secondary endpoints determined by overall animal health and well-being (Figure 12B). Tumor volume was calculated by using the formula: Tumor volume = (0.4) (ab2), where a = large diameter and b= smaller diameter.

In this study, better control of tumor growth and increased survival was seen in animals receiving target-specific 4E1 1 primary CAR-T compared to untreated control animals (Figure 12A and Figure 12B) respectively.

Example 16: Bi-specific Immune Cell Engager Functional Testing

Various experiments were performed to demonstrate the activity of the novel EGFRvlll-specific single chain variable fragment in the context of a bispecific T cell engager. Constructs were generated using synthetic DNA wherein the 4E1 1 scFV sequence (SEQ ID NO: 167) was linked to a previously demonstrated CD3-engaging scFv sequence (OKT3) to form a bi-specific engager molecule (SEQ ID NO:170). A schematic for an exemplary bi-specific immune cell engager is provided (Figure 13). A plasmid expressing this bi-specific construct was transfected into human embryonic kidney cells (HEK293T) and supernatant was collected after 2 to 4 days in culture. Supernatant from HEK293T were transferred to wells containing Jurkat cells and varying doses of antigen expressing target cells (U87vlll). Target-induced activation in the presence or absence of bispecific T-cell engager was measured by examining the level of CD69 expression using human CD69-specific antibody staining and flow cytometry (Figure 14). Data showed that only EGFRvlll targeted 4E1 1 bi-specific construct could induce high target-specific T-cell activation response compared to a control bi-specific molecule.

In vitro functionality of primary human EGFRvlll-specific bi-specific immune cell engager in interaction with primary human T cells were assessed using a live-fluorescence microscopy approach. Briefly, polyclonally expanded human T cells which were allowed to return to a rest state over several weeks in culture were placed in co-culture with EGFRvlll-expressing target cells modified to also express a nuclear-localized form of mKate2 fluorescent protein. Various doses of HEK293T supernatant, or supernatant wherein cells were secreting a control CD19-CD3 targeted or EGFRvlll-specific 4E1 1-CD3 targeted bi-specific immune cell engager were transferred to T-cell target cell co-cultures. Co-cultures were then monitored constantly over 6 days using the Incucyte™ automated live fluorescent microscopy device (Sartorius, USA). The relative growth of target cells was then assessed using automated counting of mKate2+ cells (Figure 15). Results demonstrate that 4E11-CD3 bi-specific immune cell engagers can actively induce T-cell mediated repression of EGFRvlll-positive tumour cell growth compared to the bi specific CD19-CD3 control molecule or mock supernatant.

The embodiments and examples described herein are illustrative and are not meant to limit the scope of the disclosure as claimed. Variations of the foregoing embodiments, including alternatives, modifications and equivalents, are intended by the inventors to be encompassed by the claims. Citations listed in the present application are incorporated herein by reference.

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SEQUENCE TABLE

In some sequences, CDRs are underlined and indicated in bold