WO2020148207A1

WO2020148207A1 - Human monoclonal antibodies binding to hla-a2

Info

Publication number: WO2020148207A1
Application number: PCT/EP2020/050649
Authority: WO
Inventors: Xavier SAULQUIN; Carole GUILLONNEAU; Ignacio ANEGON; Richard BREATHNACH; Mélinda MOYON; Marie-Claire DEVILDER; Laetitia GAUTREAU-ROLLAND
Original assignee: INSERM (Institut National de la Santé et de la Recherche Médicale); Université de Nantes; Université d'Angers; Centre National De La Recherche Scientifique (Cnrs); Centre Hospitalier Universitaire De Nantes
Priority date: 2019-01-14
Filing date: 2020-01-13
Publication date: 2020-07-23

Abstract

Transplantation is one of the most challenging and complex areas of medicine, and involves the transfer of a tissue or organ from a donor to a recipient patient. Rejection arises due to sensitisation of the cell-mediated immune system of the recipient to the foreign (allogeneic) antigens of the donor. In particular, the recipient's immune system reacts to the major histocompatibility complex (MHC) molecules presented on the surface of the donor tissues (the graft). In this context, there is an interest to produce anti-HLA-A2 chimeric antigen receptors (CARs) to create alloantigen-specific Tregs that can be highly suitable in transplantation. The inventors have now isolated an anti-HLA-A2 human monoclonal antibody (named as "A2Ab") of low affinity (10-6 M) and performed an affinity maturation in of said antibody. Said antibodies would be very suitable for generating CAR-Treg cells. Accordingly, the present invention relates to human monoclonal antibodies binding to HLA-A2.

Description

HUMAN MONOCLONAL ANTIBODIES BINDING TO HLA-A2

FIELD OF THE INVENTION:

The present invention relates to human monoclonal antibodies binding to HLA-A2.

BACKGROUND OF THE INVENTION:

Transplantation is one of the most challenging and complex areas of medicine, and involves the transfer of a tissue or organ from a donor to a recipient patient. It offers the possibility to replace the recipient's damaged or defective tissue or organ with a functional one and can significantly improve the health and well-being of the recipient. Organ transplantation has undergone substantial improvements in both the prevention and treatment of acute rejection, but subclinical episodes and chronic graft dysfunction still heavily impact medium- and long term graft survival. Rejection arises due to sensitisation of the cell-mediated immune system of the recipient to the foreign (allogeneic) antigens of the donor. In particular, the recipient's immune system reacts to the major histocompatibility complex (MHC) molecules presented on the surface of the donor tissues (the graft). The MHC molecules are expressed on the surface of cells in all jawed vertebrates, and are responsible for displaying antigens to cytotoxic T cells. MHC molecules also contribute to the risk of graft versus host disease (GVHD) after haematopoietic stem cell transplantation. Matching of MHC class I and II genes is essential for the success of transplantation. Graft- versus-host disease (GVHD) is associated with significant morbidity and mortality. Mortality rates as a direct or indirect consequence of GVHD can reach 50% despite the prophylactic use of immunsuppressive drugs like cyclosporine, tacrolimus, ATG, methotrexate, and mycophenolate mofetil which are administered for prevention of GVHD. In humans, genes encoding for MHC molecules are referred to as human leukocyte antigen (HLA) genes. The most intensely studied HLA genes are the nine so-called classical MHC genes: HLA-A, HLA-B, HLA-C, HLA-DPA 1 , HLA-DPB 1 , HLA-DQA 1 , HLA-DQB 1 , HLA-DRA, and HLA-DRB 1 . In humans, the MHC is divided into three regions: Class I, II, and III. The A, B, and C genes belong to MHC class I, whereas the six D genes belong to class II. Immunological rejection is typically alleviated by administering immunosuppressant drugs to the recipient, both prior to and after the transplantation. Immunosuppressants decrease the activity of the recipient's immune system, thereby preventing it from attacking the donor tissue or organ and thus allowing better graft retention. However, the administration of immunosuppressants does not result in the patient developing long-term tolerance to the allograft, and, therefore, most patients must undergo immunosuppressive therapy for the lifetime of the graft (typically 5-10 years) or the remainder of their lives. Furthermore immunosuppressants are known to cause a number of complications, largely owing to their non specificity. Emerging therapeutic strategies, among them induction of tolerance to donor antigens, are moving to the clinical stage after years of experimental model work. Among natural mechanisms and tolerance-inductive strategies, the uses of different types of regulatory cells are among the most promising ones. In particular, the uses of CD4+ and CD8+ Tregs have been highlighted in recent years. However, polyclonal Tregs encompass many specificities and could potentially be globally immunosuppressive. Thus, the use of antigen- specific Tregs seems to be preferable for the next generation of Treg therapeutic approaches. Recently chimeric antigen receptors (CARs) have been applied to create alloantigen- specific Tregs that can be highly suitable in transplantation. In particular, creation of a mouse anti-HLA-A2-specific CAR (A2-CAR) and its application in the generation of alloantigen- specific human Tregs was described in J Clin Invest. 2016 Apr 1; 126(4): 1413-24. A highly specific CAR that recognizes the HLA molecule A*02 was also described in Am J Transplant. 2017 Apr;17(4):917-930.

SUMMARY OF THE INVENTION:

As defined by the claims, the present invention relates to human monoclonal antibodies binding to HLA-A2.

DETAILED DESCRIPTION OF THE INVENTION:

The present invention relates to human monoclonal antibodies to HLA-A2. In particular, the inventors have isolated an anti-HLA-A2 human monoclonal antibody (named as“A2Ab”) of low affinity (10 ⁶ M) and performed an affinity maturation in of said antibody.

Main definitions:

As used herein, the term“HLA-A2” has its general meaning in the art and refers to a HLA serotype within the HLA-A Ά' serotype group and is encoded by the HLA-A*02 allele group including the HLA-A*02:01, HLA-A -02:02 , HLA-A -02:03, HLA- A -02:05, HLA- A*02:06, HLA-A*02:07 and HLA-A*02: 11 gene products. HLA-A2 is very common in the Caucasian population (40-50%) and provides an ideal cellular target for the first portion because it will be suitable for use in a high proportion of combinations of HLA-A2+ donors and HLA- A2- recipients. As used herein the term "antibody" or "immunoglobulin" have the same meaning, and will be used equally in the present invention. The term "antibody" as used herein refers to immunoglobulin molecules and immunologically active portions of immunoglobulin molecules, i.e., molecules that contain an antigen binding site that immunospecifically binds an antigen. As such, the term antibody encompasses not only whole antibody molecules, but also antibody fragments as well as variants (including derivatives) of antibodies and antibody fragments. In natural antibodies, two heavy chains are linked to each other by disulfide bonds and each heavy chain is linked to a light chain by a disulfide bond. There are two types of light chain, lambda (1) and kappa (k). There are five main heavy chain classes (or isotypes) which determine the functional activity of an antibody molecule: IgM, IgD, IgG, IgA and IgE. Each chain contains distinct sequence domains. The light chain includes two domains, a variable domain (VL) and a constant domain (CL). The heavy chain includes four (a, d, g) to five (m, e) domains, a variable domain (VH) and three to four constant domains (CHI, CH2, CH3 and CH4 collectively referred to as CH). The variable regions of both light (VL) and heavy (VH) chains determine binding recognition and specificity to the antigen. The constant region domains of the light (CL) and heavy (CH) chains confer important biological properties such as antibody chain association, secretion, trans-placental mobility, complement binding, and binding to Lc receptors (LcR). The Lv fragment is the N-terminal part of the Lab fragment of an immunoglobulin and consists of the variable portions of one light chain and one heavy chain. The specificity of the antibody resides in the structural complementarity between the antibody combining site and the antigenic determinant. Antibody combining sites are made up of residues that are primarily from the hypervariable or complementarity determining regions (CDRs). Occasionally, residues from nonhypervariable or framework regions (LR) can participate to the antibody binding site or influence the overall domain structure and hence the combining site. Complementarity Determining Regions or CDRs refer to amino acid sequences which together define the binding affinity and specificity of the natural Lv region of a native immunoglobulin binding site. The light and heavy chains of an immunoglobulin each have three CDRs, designated L-CDR1, L-CDR2, L- CDR3 and H-CDR1, H-CDR2, H-CDR3, respectively. An antigen-binding site, therefore, typically includes six CDRs, comprising the CDR set from each of a heavy and a light chain V region. Lramework Regions (LRs) refer to amino acid sequences interposed between CDRs.

According to the invention, the amino acid residues in the variable domain, complementarity determining regions (CDRs) and framework regions (LR) of the antibody of the present invention are identified using the Immunogenetics (IMGT) database (http://imgt.cines.fr). Lefranc et al. (2003) Dev Comp Immunol. 27(l):55-77. The IMGT database was developed using sequence information for immunoglobulins (IgGs), T-cell receptors (TcR) and Major Histocompatibility Complex (MHC) molecules and unifies numbering across antibody lambda and kappa light chains, heavy chains and T-cell receptor chains and avoids the use of insertion codes for all but uncommonly long insertions. IMGT also takes into account and combines the definition of the framework (FR) and complementarity determining regions (CDR) from Rabat et al., the characterization of the hypervariable loops from Chothia et al., as well as structural data from X-ray diffraction studies.

As used herein the term "human antibody" as used herein, is intended to include antibodies having variable and constant regions derived from human immunoglobulin sequences. The human antibodies of the present invention may include amino acid residues not encoded by human immunoglobulin sequences (e.g., mutations introduced by random or site- specific mutagenesis in vitro or by somatic mutation in vivo). However, the term "human antibody", as used herein, is not intended to include antibodies in which CDR sequences derived from the germline of another mammalian species, such as a mouse, have been grafted onto human framework sequences.

The terms "monoclonal antibody", "monoclonal Ab", "monoclonal antibody composition", "mAh", or the like, as used herein refer to a preparation of antibody molecules of single molecular composition. A monoclonal antibody composition displays a single binding specificity and affinity for a particular epitope. Accordingly, the term "human monoclonal antibody" refers to antibodies displaying a single binding specificity which have variable and constant regions derived from human germline immunoglobulin sequences.

According to the present invention, the heavy chain of the A2Ab antibody consists of the sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 474 in SEQ ID NO: l. According to the present invention the VH domain of the A2Ab antibody consists of the sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 144 in SEQ ID NO: 1.

SEQ ID NO:l: heavy chain of the A2Ab antibody

FR2-CDR2-FR3-CDR3-FR4- constant region MGWSCI ILFLVATATGVHSEVOEEESGAEVKKPGESLKI SCKASGYRFTNYWIGWVRQMPGKGLEWMGI IYPYDSDTOYSPSFOGOVTISADKSTTTAYLHWSSLKASDTAMYYCVKLRGGFVRWFAPYFDSWGOGTLVTVSS ASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSWTVPSSS LGTQTYICNVNHKPSNTKVDKRVEPKSCDKTHTCPPCPAPELLGGPSVFLFPPKPKDTLMISRTPEVTCVWDVS HEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRWSVL TVLHQDWLNGKE YKCKVSNKALPAPIEKTISKAKGQ PREPQVYTLPP SRDEL TKNQVSL TCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFL YSKL TVDKSRW QQGNVFSCSVMHEALHNHYTQKSLSLSPGK *

According to the present invention, the light chain of the A2Ab antibody consists of the sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 236 in SEQ ID NO:2. According to the present invention the VL domain of the A2Ab antibody consists of the sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 133 in SEQ ID NO:2.

SEQ ID NO: 2: light chain of the A2Ab antibody leader sequence-FRl-CDRl- FR2-CDR2-FR3-CDR3-FR4-constant region

MGtVSCJJLFLVATArGStVAOSALTOPRSVSGSPGOSVTI SCTGSRSDAHTFNYVSWYOOHPGKAPKLMI CDVNORPSGVPDRFSGSKSGDAASLTI SGLOAEDEADYYCFSYDANYTLGVFGTGTKVTVLSOPKAJVPryTLFPP SSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQWKSHRSYSCQV THEGS TVEKTVAP TECS *

As used herein, the term“scFv” refers to a fusion protein comprising at least one antibody fragment comprising a variable region of a light chain and at least one antibody fragment comprising a variable region of a heavy chain, wherein the light and heavy chain variable regions are contiguously linked, e.g., via a synthetic linker, e.g., a short flexible polypeptide linker, and capable of being expressed as a single chain polypeptide, and wherein the scFv retains the specificity of the intact antibody from which it is derived. Unless specified, as used herein an scFv may have the VL and VH variable regions in either order, e.g., with respect to the N-terminal and C-terminal ends of the polypeptide, the scFv may comprise VL- linker-VH or may comprise VH-linker-VL.

As used herein, the term "binding" in the context of the binding of an antibody to a predetermined antigen or epitope typically is a binding with a low affinity corresponding to a K_D of about 10 ⁶ M when determined by for instance surface plasmon resonance (SPR) technology in a BIAcore 3000 instrument using a soluble form of the antigen as the ligand and the antibody as the analyte. BIACORE® (GE Healthcare, Piscaataway, NJ) is one of a variety of surface plasmon resonance assay formats that are routinely used to epitope bin panels of monoclonal antibodies. Typically, an antibody binds to the predetermined antigen with an affinity corresponding to a KD that is at least ten-fold lower, such as at least 100-fold lower, for instance at least 1,000-fold lower, such as at least 10,000-fold lower, for instance at least 100,000-fold lower than its KD for binding to a non-specific antigen (e.g., BSA, casein), which is not identical or closely related to the predetermined antigen. When the KD of the antibody is very low (that is, the antibody has a high affinity), then the KD with which it binds the antigen is typically at least 10,000-fold lower than its KD for a non-specific antigen. An antibody is said to essentially not bind an antigen or epitope if such binding is either not detectable (using, for example, plasmon resonance (SPR) technology in a BIAcore 3000 instrument using a soluble form of the antigen as the ligand and the antibody as the analyte), or is 100 fold, 500 fold, 1000 fold or more than 1000 fold less than the binding detected by that antibody and an antigen or epitope having a different chemical structure or amino acid sequence.

Antibodies of the present invention:

The first object of the present invention relates to a human monoclonal antibody which comprises:

a heavy chain comprising i) the H-CDR1 as set forth in SEQ ID NO:3, ii) the H- CDR2 as set forth in SEQ ID NO:4 and iii) the H-CDR3 as set forth in SEQ ID NO:5, and,

a light chain comprising i) the L-CDR1 as set forth in SEQ ID NO:6, ii) the L- CDR2 as set forth in SEQ ID NO:7 and iii) the L-CDR3 as set forth in SEQ ID NO:8.

SEQ ID NO: 3 (H-CDR1) : GYRFTNYW

SEQ ID NO: 4 (H-CDR2 ) : IYPY-X₅-SDT wherein X₅ represents D or H

SEQ ID NO : 5 (H-CDR3) : VRLRG-Xe-FV-Xg-WFAPYFDS wherein X₆ represents G, D or E and X₉ represents P or R.

SEQ ID NO: 6 (L-CDR1) : RSDAHTFNY

SEQ ID NO: 7 (L-CDR2 ) : DVN

SEQ ID NO : 8 (L-CDR3) : FSYDANYTLGV

The present invention thus provides antibodies comprising functional variants of the VL region, VH region, or one or more functional variants of the CDRs of A2Ab. A functional variant of a VL, VH, or CDR used in the context of a human monoclonal antibody of the present invention still allows the antibody to retain at least a substantial proportion (at least about 50%, 60%, 70%, 80%, 90%, 95% or more) of the affinity/avidity and/or the specificity/selectivity of the parent antibody (i.e. A2Ab antibody) and in some cases such a human monoclonal antibody of the present invention may be associated with greater affinity, selectivity and/or specificity than the parent Ab. Such functional variants typically retain significant sequence identity to the parent Ab. The sequence of CDR variants may differ from the sequence of the CDR of the parent antibody sequences through mostly conservative substitutions; for instance at least about 35%, about 50% or more, about 60% or more, about 70% or more, about 75% or more, about 80% or more, about 85% or more, about 90% or more, (e.g., about 65-95%, such as about 92%, 93% or 94%) of the substitutions in the variant are conservative amino acid residue replacements. The sequences of CDR variants may differ from the sequence of the CDRs of the parent antibody sequences through mostly conservative substitutions; for instance at least 10, such as at least 9, 8, 7, 6, 5, 4, 3, 2 or 1 of the substitutions in the variant are conservative amino acid residue replacements. In the context of the present invention, conservative substitutions may be defined by substitutions within the classes of amino acids reflected as follows:

Aliphatic residues I, L, V, and M

Cycloalkenyl-associated residues F, H, W, and Y

Hydrophobic residues A, C, F, G, H, I, L, M, R, T, V, W, and Y

Negatively charged residues D and E

Polar residues C, D, E, H, K, N, Q, R, S, and T

Positively charged residues H, K, and R

Small residues A, C, D, G, N, P, S, T, and V

Very small residues A, G, and S

Residues involved in turn A, C, D, E, G, H, K, N, Q, R, S, P, and formation T

Flexible residues Q, T, K, S, G, P, D, E, and R

More conservative substitutions groupings include: valine-leucine-isoleucine, phenylalanine-tyrosine, lysine-arginine, alanine-valine, and asparagine-glutamine. Conservation in terms of hydropathic/hydrophilic properties and residue weight/size also is substantially retained in a variant CDR as compared to a CDR of A2Ab. The importance of the hydropathic amino acid index in conferring interactive biologic function on a protein is generally understood in the art. It is accepted that the relative hydropathic character of the amino acid contributes to the secondary structure of the resultant protein, which in turn defines the interaction of the protein with other molecules, for example, enzymes, substrates, receptors, DNA, antibodies, antigens, and the like. Each amino acid has been assigned a hydropathic index on the basis of their hydrophobicity and charge characteristics these are: isoleucine (+4.5); valine (+4.2); leucine (+3.8) ; phenylalanine (+2.8); cysteine/cystine (+2.5); methionine (+1.9); alanine (+1.8); glycine (-0.4); threonine (-0.7); serine (-0.8); tryptophane (-0.9); tyrosine (-1.3); proline (-1.6); histidine (-3.2); glutamate (-3.5); glutamine (-3.5); aspartate (-3.5); asparagine (- 3.5); lysine (-3.9); and arginine (-4.5). The retention of similar residues may also or alternatively be measured by a similarity score, as determined by use of a BLAST program (e.g., BLAST 2.2.8 available through the NCBI using standard settings BLOSUM62, Open Gap= 1 1 and Extended Gap= 1). Suitable variants typically exhibit at least about 70% of identity to the parent peptide. According to the present invention a first amino acid sequence having at least 70% of identity with a second amino acid sequence means that the first sequence has 70; 71; 72; 73; 74; 75; 76; 77; 78; 79; 80; 81; 82; 83; 84; 85; 86; 87; 88; 89; 90; 91; 92; 93; 94; 95; 96; 97; 98; 99; or 100% of identity with the second amino acid sequence.

In some embodiments, the human monoclonal antibody of the present invention comprises a VH domain consisting of the amino acid sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 144 in SEQ ID NO: l.

In some embodiments, the human monoclonal antibody of the present invention comprises a VH domain characterized by the presence of mutations as depicted in Table I or II.

In some embodiments, the human monoclonal antibody of the present invention comprises a VH domain of the amino acid sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 144 in SEQ ID NO: l comprising at least one mutation selected from the group consisting of:

the (D) residue at position 74 in SEQ ID NO: 1 is substituted by a (H) residue the (S) residue at position 80 in SEQ ID NO: 1 is substituted by a (T) residue) the (W) residue at position 102 in SEQ ID NO: l is substituted by a (L) residue the (M) residue at position 112 in SEQ ID NO: 1 is substituted by a (I) residue the (G) residue at position 121 in SEQ ID NO: l is substituted by a (D) residue the (R) residue at position 124 in SEQ ID NO: l is substituted by a (P) residue.

In some embodiments, the human monoclonal antibody of the present invention comprises a VH domain of the amino acid sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 144 in SEQ ID NO: l wherein:

the (D) residue at position 74 in SEQ ID NO: 1 is substituted by a (H) residue the (W) residue at position 102 in SEQ ID NO: l is substituted by a (L) residue the (M) residue at position 112 in SEQ ID NO: 1 is substituted by a (I) residue the (G) residue at position 121 in SEQ ID NO: l is substituted by a (D) residue the (R) residue at position 124 in SEQ ID NO: l is substituted by a (P) residue.

In some embodiments, the human monoclonal antibody of the present invention comprises a VL domain consisting of the sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 133 in SEQ ID NO:2.

The antibody of the present invention can be characterized by one or more of the functional or structural features of the aspects described above, or by any combination of selected functional and structural features.

The antibody of the present invention may be of any isotype. The choice of isotype typically will be guided by the desired effector functions, such as ADCC induction. Exemplary isotypes are IgGl, IgG2, IgG3, and IgG4. Either of the human light chain constant regions, kappa or lambda, may be used. If desired, the class of a human monoclonal antibody of the present invention may be switched by known methods. Typical, class switching techniques may be used to convert one IgG subclass to another, for instance from IgGl to IgG2. Thus, the effector function of the human monoclonal antibodies of the present invention may be changed by isotype switching to, e.g., an IgGl, IgG2, IgG3, IgG4, IgD, IgA, IgE, or IgM antibody for various therapeutic uses. In some embodiments, the antibody of the present invention is a full- length antibody. In some embodiments, the full-length antibody is an IgGl antibody. In some embodiments, the full-length antibody is an IgG4 antibody. In some embodiments, the HLA- A2-specific IgG4 antibody is a stabilized IgG4 antibody. Examples of suitable stabilized IgG4 antibodies are antibodies wherein arginine at position 409 in a heavy chain constant region of human IgG4, which is indicated in the EU index as in Rabat et al. supra, is substituted with lysine, threonine, methionine, or leucine, preferably lysine (described in W02006033386) and/or wherein the hinge region comprises a Cys-Pro-Pro-Cys sequence. Other suitable stabilized IgG4 antibodies are disclosed in WO2008145142, which is hereby incorporated by reference in its entirety. In some embodiments, the human monoclonal antibody of the present invention is an antibody of a non-IgG4 type, e.g. IgGl, IgG2 or IgG3 which has been mutated such that the ability to mediate effector functions, such as ADCC, has been reduced or even eliminated. Such mutations have e.g. been described in Dall'Acqua WF et al., J Immunol. 177(2) : 1129-1138 (2006) and Hezareh M, J Virol. 75(24) : 12161-12168 (2001).

In addition or alternative to modifications made within the framework or CDR regions, antibodies of the present invention may be engineered to include modifications within the Fc region, typically to alter one or more functional properties of the antibody, such as serum half- life, complement fixation, Fc receptor binding, and/or antigen-dependent cellular cytotoxicity. Furthermore, a human monoclonal antibody of the present invention may be chemically modified (e.g., one or more chemical moieties can be attached to the antibody) or be modified to alter its glycosylation, again to alter one or more functional properties of the antibody. For example, it will be appreciated that the affinity of antibodies provided by the present invention may be altered using any suitable method known in the art. The present invention therefore also relates to variants of the antibody molecules of the present invention, which have an improved affinity for HLA-A2. Such variants can be obtained by a number of affinity maturation protocols including mutating the CDRs (Yang et al., J. Mol. Biol., 254, 392-403, 1995), chain shuffling (Marks et al., Bio/Technology, 10, 779-783, 1992), use of mutator strains of E. coli (Low et al., J. Mol. Biol., 250, 359-368, 1996), DNA shuffling (Patten et al., Curr. Opin. BiotechnoL, 8, 724-733, 1997), phage display (Thompson et al., J. Mol. Biol., 256, 77-88, 1996) and sexual PCR (Crameri et al., Nature, 391, 288-291, 1998). Vaughan et al. (supra) discusses these methods of affinity maturation.

In some embodiments, the Fc region is altered by replacing at least one amino acid residue with a different amino acid residue to alter the effector functions of the antibody. For example, one or more amino acids can be replaced with a different amino acid residue such that the antibody has an altered affinity for an effector ligand but retains the antigen-binding ability of the parent antibody. The effector ligand to which affinity is altered can be, for example, an Fc receptor or the Cl component of complement. This approach is described in further detail in U.S. Patent Nos. 5,624,821 and 5,648,260, both by Winter et al.

In some embodiments, one or more amino acids selected from amino acid residues can be replaced with a different amino acid residue such that the antibody has altered Clq binding and/or reduced or abolished complement dependent cytotoxicity (CDC). This approach is described in further detail in U.S. Patent Nos. 6,194,551 by ldusogie et al.

In some embodiments, one or more amino acid residues are altered to thereby alter the ability of the antibody to fix complement. This approach is described further in PCT Publication WO 94/29351 by Bodmer et al. In some embodiments, the Fc region is modified to increase the ability of the antibody to mediate antibody dependent cellular cytotoxicity (ADCC) and/or to increase the affinity of the antibody for an Fc receptor by modifying one or more amino acids. This approach is described further in PCT Publication WO 00/42072 by Presta. Moreover, the binding sites on human IgGI for FcyRI, FcyRII, FcyRIII and FcRn have been mapped and variants with improved binding have been described (see Shields, R. L. et al, 2001 J. Biol. Chen. 276:6591-6604, W02010106180).

In some embodiments, the glycosylation of an antibody is modified. For example, an aglycoslated antibody can be made (i.e., the antibody lacks glycosylation). Glycosylation can be altered to, for example, increase the affinity of the antibody for the antigen. Such carbohydrate modifications can be accomplished by, for example, altering one or more sites of glycosylation within the antibody sequence. For example, one or more amino acid substitutions can be made that result in elimination of one or more variable region framework glycosylation sites to thereby eliminate glycosylation at that site. Such aglycosylation may increase the affinity of the antibody for antigen. Such an approach is described in further detail in U.S. Patent Nos. 5,714,350 and 6,350,861 by Co et al. Additionally or alternatively, an antibody can be made that has an altered type of glycosylation, such as a hypofucosylated or non-fucosylated antibody having reduced amounts of or no fucosyl residues or an antibody having increased bisecting GlcNac structures. Such altered glycosylation patterns have been demonstrated to increase the ADCC ability of antibodies. Such carbohydrate modifications can be accomplished by, for example, expressing the antibody in a host cell with altered glycosylation machinery. Cells with altered glycosylation machinery have been described in the art and can be used as host cells in which to express recombinant antibodies of the present invention to thereby produce an antibody with altered glycosylation. For example, EP 1 ,176,195 by Hang et al. describes a cell line with a functionally disrupted FUT8 gene, which encodes a fucosyl transferase, such that antibodies expressed in such a cell line exhibit hypofucosylation or are devoid of fucosyl residues. Therefore, in some embodiments, the human monoclonal antibodies of the present invention may be produced by recombinant expression in a cell line which exhibit hypofucosylation or non-fucosylation pattern, for example, a mammalian cell line with deficient expression of the FUT8 gene encoding fucosyltransferase. PCT Publication WO 03/035835 by Presta describes a variant CHO cell line, Lecl3 cells, with reduced ability to attach fucose to Asn(297)-linked carbohydrates, also resulting in hypofucosylation of antibodies expressed in that host cell (see also Shields, R.L. et al, 2002 J. Biol. Chem. 277:26733-26740). PCT Publication WO 99/54342 by Umana et al. describes cell lines engineered to express glycoprotein-modifying glycosyl transferases (e.g., beta(l,4)-N acetylglucosaminyltransferase III (GnTIII)) such that antibodies expressed in the engineered cell lines exhibit increased bisecting GlcNac structures which results in increased ADCC activity of the antibodies (see also Umana et al, 1999 Nat. Biotech. 17: 176-180). Eureka Therapeutics further describes genetically engineered CHO mammalian cells capable of producing antibodies with altered mammalian glycosylation pattern devoid of fucosyl residues (http://www.eurekainc.com/a&boutus/companyoverview.html). Alternatively, the human monoclonal antibodies of the present invention can be produced in yeasts or filamentous fungi engineered for mammalian- like glycosylation pattern and capable of producing antibodies lacking fucose as glycosylation pattern (see for example EP1297172B 1 ).

In some embodiments, the antibody is an antigen-binding fragment. Antibody fragments can be obtained by conventional techniques, such as by fragmentation of full-length antibodies or by expression of nucleic acids encoding antibody fragments in recombinant cells (see, for instance Evans et al., J. Immunol. Meth. 184, 123-38 (1995)). The fragments can then be tested or screened for their properties in the same manner as described herein for full-length antibodies. In some embodiments, the fragment is a scFv fragment comprising the VH and the VL domain of the antibody of the present invention.

Nucleic acid molecules and uses thereof for manufacturins the antibodies of the present invention:

The human monoclonal antibody of the present invention may be produced by any technique known in the art, such as, without limitation, any chemical, biological, genetic or enzymatic technique, either alone or in combination. For example, knowing the amino acid sequence of the desired sequence, one skilled in the art can readily produce said antibodies, by standard techniques for production of polypeptides. For instance, they can be synthesized using well-known solid phase method, preferably using a commercially available peptide synthesis apparatus (such as that made by Applied Biosystems, Foster City, California) and following the manufacturer' s instructions. Alternatively, antibodies of the present invention can be synthesized by recombinant DNA techniques well-known in the art. For example, antibodies can be obtained as DNA expression products after incorporation of DNA sequences encoding the antibodies into expression vectors and introduction of such vectors into suitable eukaryotic or prokaryotic hosts that will express the desired antibodies, from which they can be later isolated using well-known techniques.

Accordingly, a further object of the present invention relates to a nucleic acid sequence encoding a human monoclonal antibody of the present invention. In some embodiments, the nucleic acid sequence encodes a heavy chain and/or a light chain of a human monoclonal antibody of the present invention.

Typically, said nucleic acid is a DNA or RNA molecule, which may be included in any suitable vector. The term "vector," as used herein, is intended to refer to a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked. One type of vector is a "plasmid", which refers to a circular double stranded DNA loop into which additional DNA segments may be ligated. Another type of vector is a viral vector, wherein additional DNA segments may be ligated into the viral genome. Certain vectors are capable of autonomous replication in a host cell into which they are introduced (for instance bacterial vectors having a bacterial origin of replication and episomal mammalian vectors). Other vectors (such as non- episomal mammalian vectors) may be integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. Moreover, certain vectors are capable of directing the expression of genes to which they are operatively linked. Such vectors are referred to herein as "recombinant expression vectors" (or simply, "expression vectors"). In general, expression vectors of utility in recombinant DNA techniques are often in the form of plasmids. In the present specification, "plasmid" and "vector" may be used interchangeably as the plasmid is the most commonly used form of vector. However, the present invention is intended to include such other forms of expression vectors, such as viral vectors (such as replication-defective retroviruses, adenoviruses and adeno-associated viruses), which serve equivalent functions.

So, a further object of the present invention relates to a vector comprising a nucleic acid of the present invention.

Such vectors may comprise regulatory elements, such as a promoter, enhancer, terminator and the like, to cause or direct expression of said antibody upon administration to a subject. Examples of promoters and enhancers used in the expression vector for animal cell include early promoter and enhancer of SV40 (Mizukami T. et al. 1987), LTR promoter and enhancer of Moloney mouse leukemia virus (Kuwana Y et al. 1987), promoter (Mason JO et al. 1985) and enhancer (Gillies SD et al. 1983) of immunoglobulin H chain and the like. Any expression vector for animal cell can be used, so long as a gene encoding the human antibody C region can be inserted and expressed. Examples of suitable vectors include pAGE107 (Miyaji H et al. 1990), pAGE103 (Mizukami T et al. 1987), pHSG274 (Brady G et al. 1984), pKCR (O'Hare K et al. 1981), pSGl beta d2-4-(Miyaji H et al. 1990) and the like. Other examples of plasmids include replicating plasmids comprising an origin of replication, or integrative plasmids, such as for instance pUC, pcDNA, pBR, and the like. Other examples of viral vector include adenoviral, retroviral, herpes virus and AAV vectors. Such recombinant viruses may be produced by techniques known in the art, such as by transfecting packaging cells or by transient transfection with helper plasmids or viruses. Typical examples of virus packaging cells include PA317 cells, PsiCRIP cells, GPenv+ cells, 293 cells, etc. Detailed protocols for producing such replication-defective recombinant viruses may be found for instance in WO 95/14785, WO 96/22378, US 5,882,877, US 6,013,516, US 4,861,719, US 5,278,056 and WO 94/19478.

A further object of the present invention relates to a host cell which has been transfected, infected or transformed by a nucleic acid and/or a vector according to the present invention.

The term "transformation" means the introduction of a "foreign" (i.e. extrinsic or extracellular) gene, DNA or RNA sequence to a host cell, so that the host cell will express the introduced gene or sequence to produce a desired substance, typically a protein or enzyme coded by the introduced gene or sequence. A host cell that receives and expresses introduced DNA or RNA has been "transformed».

The nucleic acids of the present invention may be used to produce a human monoclonal antibody of the present invention in a suitable expression system. The term "expression system" means a host cell and compatible vector under suitable conditions, e.g. for the expression of a protein coded for by foreign DNA carried by the vector and introduced to the host cell. Common expression systems include E. coli host cells and plasmid vectors, insect host cells and Baculo virus vectors, and mammalian host cells and vectors. Other examples of host cells include, without limitation, prokaryotic cells (such as bacteria) and eukaryotic cells (such as yeast cells, mammalian cells, insect cells, plant cells, etc.). Specific examples include E.coli, Kluyveromyces or Saccharomyces yeasts, mammalian cell lines (e.g., Vero cells, CHO cells, 3T3 cells, COS cells, etc.) as well as primary or established mammalian cell cultures (e.g., produced from lymphoblasts, fibroblasts, embryonic cells, epithelial cells, nervous cells, adipocytes, etc.). Examples also include mouse SP2/0-Agl4 cell (ATCC CRL1581), mouse P3X63-Ag8.653 cell (ATCC CRL1580), CHO cell in which a dihydrofolate reductase gene (hereinafter referred to as "DHFR gene") is defective (Urlaub G et al; 1980), rat YB2/3HL.P2.G1 1.16Ag.20 cell (ATCC CRL1662, hereinafter referred to as "YB2/0 cell"), and the like.

The present invention also relates to a method of manufacturing a recombinant host cell expressing an antibody according to the present invention, said method comprising the steps of: (i) introducing in vitro or ex vivo a recombinant nucleic acid or a vector as described above into a competent host cell, (ii) culturing in vitro or ex vivo the recombinant host cell obtained and (iii), optionally, selecting the cells which express and/or secrete said antibody. Such recombinant host cells can be used for the production of antibodies of the present invention.

Chimeric antigen receptors ( CARs) and uses thereof for manufacturins host cells that express said CARs:

The present invention also provides chimeric antigen receptors (CARs) comprising an antigen binding domain of the antibody of the present invention.

As used herein, the term“chimeric antigen receptor” or“CAR” has its general meaning in the art and refers to an artificially constructed hybrid protein or polypeptide containing the antigen binding domains of an antibody (e.g., scFv) linked to T- cell signaling domains. Characteristics of CARs include their ability to redirect T-cell specificity and reactivity toward a selected target in a non-MHC-restricted manner, exploiting the antigen-binding properties of monoclonal antibodies. Moreover, when expressed in T-cells, CARs advantageously do not dimerize with endogenous T cell receptor (TCR) alpha and beta chains. Typically, said chimeric antigen receptor comprises at least one VH and/or VF sequence of the antibody of the present invention. The chimeric antigen receptor the present invention also comprises an extracellular hinge domain, a transmembrane domain, and an intracellular T cell signaling domain.

In some embodiments, the invention provides CARs comprising an antigen-binding domain comprising, consisting of, or consisting essentially of, a single chain variable fragment (scFv) of the antibody of the present invention. In some embodiments, the antigen binding domain comprises a linker peptide. The linker peptide may be positioned between the light chain variable region and the heavy chain variable region.

In some embodiments, the CAR comprises an extracellular hinge domain, a transmembrane domain, and an intracellular T cell signaling domain selected from the group consisting of CD28, 4-1BB, and€ϋ3z intracellular domains. CD28 is a T cell marker important in T cell co-stimulation. 4- IBB transmits a potent costimulatory signal to T cells, promoting differentiation and enhancing long-term survival of T lymphocytes. Oϋ3z associates with TCRs to produce a signal and contains immunoreceptor tyrosine-based activation motifs (IT AMs).

In some embodiments, the chimeric antigen receptor of the present invention can be glycosylated, amidated, carboxylated, phosphorylated, esterified, N-acylated, cyclized via, e.g., a disulfide bridge, or converted into an acid addition salt and/or optionally dimerized or polymerized.

The invention also provides a nucleic acid encoding for a chimeric antigen receptor of the present invention. In some embodiments, the nucleic acid is incorporated in a vector as such as described above.

Thus, a further object of the present invention relates to a host cell engineered to express a chimeric antigen receptor (CAR) as above described.

In some embodiments, the host cell is a T cell, e.g. isolated from peripheral blood lymphocytes (PBL) or peripheral blood mononuclear cells (PBMC). In some embodiments, the T cell can be any T cell, such as a cultured T cell, e.g., a primary T cell, or a T cell from a cultured T cell line, e.g., Jurkat, SupTl, etc., or a T cell obtained from a mammal. If obtained from a mammal, the T cell can be obtained from numerous sources, including but not limited to blood, bone marrow, lymph node, the thymus, or other tissues or fluids. T cells can also be enriched for or purified. The T cell can be any type of T cell and can be of any developmental stage, including but not limited to, CD4+/CD8+ double positive T cells, CD4+ helper T cells, e.g., Th2 cells, CD8+ T cells (e.g., cytotoxic T cells), tumor infiltrating cells, memory T cells, naive T cells, and the like. The T cell may be a CD8+ T cell or a CD4+ T cell. In some embodiments, the host cell is a Treg. As used herein, the term“Treg” or“T regulatory cell” denotes a T lymphocyte endowed with a given antigen specificity imprinted by the TCR it expresses and with regulatory properties defined by the ability to suppress the response of conventional T lymphocytes or other immune cells. Such responses are known in the art and include, but are not limited to, cytotoxic activity against antigen-presenting target cells and secretion of different cytokines. Different types of Tregs exist and include, but are not limited to: inducible and thymic-derived Tregs, as characterized by different phenotypes such as CD4+CD25+/high, CD4+CD25+/highCD127-/low alone or in combination with additional markers that include, but are not limited to, FoxP3, neuropilin-1 (CD304), glucocorticoid- induced TNFR-related protein (GITR), cytotoxic T-lymphocyte-associated protein 4 (CTLA- 4, CD152); T regulatory type 1 cells; T helper 3 cells. In some embodiments, the Treg is CD4+ Foxp3+ Treg cell or a CD8+ Foxp3+ Treg cells or a CD4+CD45RC^low/ Treg or a CD8+CD45RC^low/ cells or CD4+Foxp3- Trl Tregs. All these Tregs can be transformed with the CAR of the present invention either upon direct ex vivo purification or upon in vitro expansion or differentiation from different precursor cells. Examples of in vitro amplification protocols can be found in Battaglia et ah, J. Immunol. 177:8338-8347 (2006), Putnam et ah, Diabetes 58:652-662 (2009), Gregori et ah, Blood 116:935-944 (2009).

In some embodiments, the host cell is a pluripotent stem cell (PSC). PSCs can be indeed be modified by a CAR and then can be used for deriving T cells (e.g. WO 2017100403). PSCs include embryonic stem cell (ESCs) and induced pluripotent stem cell (iPSCs). iPSCs can be generated directly from adult cells (e.g., somatic cells). iPSCs can be typically derived or generated by introducing a specific set of pluripotency-associated genes, or "reprogramming factors", into a given cell type. Reprogramming factors include, but are not limited to, OCT4 (also known as "POU5FL"), SOX2, cMYC, and KLF4, which are also known as Yamanaka factors. See Takahashi, K; Yamanaka, S (2006). "Induction of pluripotent stem cells from mouse embryonic and adult fibroblast cultures by defined factors". Cell 126 (4): 663-76.

In some embodiments, the host cell is a hematopoietic stem cell. As used herein, the term“hematopoietic stem cell” or“FISC” refers to blood cells that have the capacity to self- renew and to differentiate into precursors of blood cells. These precursor cells are immature blood cells that cannot self-renew and must differentiate into mature blood cells. Hematopoietic stem progenitor cells display a number of phenotypes, such as Lin- CD34+CD38-CD90+CD45RA-, Lin-CD34+CD38-CD90-CD45RA-, Lin- CD34+CD38+IL-3aloCD45RA- and Lin-CD34+CD38+CD10+(Daley et al., Focus 18:62-67, 1996; Pimentel, E., Ed., Handbook of Growth Factors Vol. Ill: Hematopoietic Growth Factors and Cytokines, pp. 1-2, CRC Press, Boca Raton, Fla., 1994). Within the bone marrow microenvironment, the stem cells self-renew and maintain continuous production of hematopoietic stem cells that give rise to all mature blood cells throughout life. In some embodiments, the hematopoietic progenitor cells or hematopoietic stem cells are isolated form peripheral blood cells.

In some embodiments, the CAR activity can be controlled if desirable to optimize the safety and efficacy of a CAR therapy. There are many ways CAR activities can be regulated. For example, inducible apoptosis using, e.g., a caspase fused to a dimerization domain (see, e.g., Di et al., N Egnl. J. Med. 2011 Nov. 3; 365(18): 1673- 1683), can be used as a safety switch in the CAR therapy of the instant invention.

The population of those cells prepared as described above can be utilized in methods and compositions for adoptive immunotherapy in accordance with known techniques, or variations thereof that will be apparent to those skilled in the art based on the instant disclosure. See, e.g., US Patent Application Publication No. 2003/0170238 to Gruenberg et al; see also US Patent No. 4,690,915 to Rosenberg. The adoptive immunotherapy with regulatory T cells (Tregs) according to the invention is particularly suitable for the treatment of allograft rejection and graft- versus-host disease (GVHD). In some embodiments, the subject is thus a transplanted subject. Typically the subject may have been transplanted with a graft selected from the group consisting of heart, kidney, lung, liver, pancreas, pancreatic islets, brain tissue, stomach, large intestine, small intestine, cornea, skin, trachea, bone, bone marrow, muscle, or bladder. The method of the invention is indeed particularly suitable for preventing or suppressing an immune response associated with rejection of a donor tissue, cell, graft, or organ transplant by a recipient subject. Graft-related diseases or disorders include graft versus host disease (GVDH), such as associated with bone marrow transplantation, and immune disorders resulting from or associated with rejection of organ, tissue, or cell graft transplantation (e.g., tissue or cell allografts or xenografts), including, e.g., grafts of skin, muscle, neurons, islets, organs, parenchymal cells of the liver, etc. With regard to a donor tissue, cell, graft or solid organ transplant in a recipient subject, it is believed that the adoptive immunotherapy according to the invention may be effective in preventing acute rejection of such transplant in the recipient and/or for long-term maintenance therapy to prevent rejection of such transplant in the recipient (e.g., inhibiting rejection of insulin-producing islet cell transplant from a donor in the subject recipient suffering from diabetes). Thus the adoptive immunotherapy of the invention is useful for preventing Host-Versus-Graft-Disease (HVGD) and Graft- Versus-Host-Disease (GVHD). Typically, the cells may be administered to the subject before and/or after transplantation. In some embodiments, the cells inhibitor may be administered to the subject on a periodic basis before and/or after transplantation.

Currently, most adoptive immunotherapies are autolymphocyte therapies (ALT) directed to treatments using the patient's own immune cells. These therapies involve processing the patient's own lymphocytes to enhance the tolerance response towards specific antigens presented in the HLA-A2 context. Typically, the treatments are accomplished by removing the patient's lymphocytes and exposing these cells in vitro to biologies and drugs to convey them to a Treg profile as above described. Once the Treg cells are prepared with the CAR of the present invention, these ex vivo cells are reinfused into the patient to enhance the immune system to induce tolerance. In some embodiments, the cells are formulated by first harvesting them from their culture medium, and then washing and concentrating the cells in a medium and container system suitable for administration (a "pharmaceutically acceptable" carrier) in a treatment-effective amount. Suitable infusion medium can be any isotonic medium formulation, typically normal saline, Normosol R (Abbott) or Plasma- Lyte A (Baxter), but also 5% dextrose in water or Ringer's lactate can be utilized. The infusion medium can be supplemented with human serum albumin. A treatment-effective amount of cells in the composition is dependent on the relative representation of the T cells with the desired specificity, on the age and weight of the recipient, on the severity of the targeted condition and on the immunogenicity of the targeted Ags. These amount of cells can be as low as approximately 10³/kg, preferably 5xl0³/kg; and as high as 10⁷/kg, preferably 10⁸/kg. The number of cells will depend upon the ultimate use for which the composition is intended, as will the type of cells included therein. For example, if cells that are specific for a particular Ag are desired, then the population will contain greater than 70%, generally greater than 80%, 85% and 90-95% of such cells. For uses provided herein, the cells are generally in a volume of a liter or less, can be 500 ml or less, even 250 ml or 100 ml or less. The clinically relevant number of immune cells can be apportioned into multiple infusions that cumulatively equal or exceed the desired total amount of cells.

The invention will be further illustrated by the following figures and examples. However, these examples and figures should not be interpreted in any way as limiting the scope of the present invention. FIGURES:

Figure 1: Isolation and characterization of human mAh A2Ab. (A) Sorting strategy used to isolate HLA-A2- specific B lymphocytes from donor NO. Cells with the following phenotypic characteristics: CD3-, CD19+ (left panel), both PE and APC labeled HLA-A2 tetramers+ (middle panel), HLA-B7 tetramer BV421- (right panel) were isolated and used to produce recombinant antibodies. (B) A2Ab Ab in Fig. IB and a control anti- pp65-HLA- A*0201 human mAh (Ac-anti pp65-A2) were tested by ELISA against the following peptide- MHC recombinant monomers: pp65-HLA-A*0201 (pp65-A2), MelA-HLA-A*0201 (MelA- A2) and pUV-HLA-B*0701 (pUV-B7). C) The specificity of A2Ab was assessed in a Luminex single antigen bead assay. Results are shown in terms of interval MFI. Positivity threshold was set at 1000. (D) The affinity of A2Ab was measured by surface plasmon resonance by flowing various concentrations of pp65-A2 complex over CM5 chip-bound A2Ab.

Figure 2: Generation and selection of HEK 293 cells expressing affinity-matured antibodies. (A) Overall strategy for antibody affinity maturation. HEK 293 cells expressing the initial Ab are subjected to CRISPR-X mutagenesis. Cells expressing variant antibodies of higher avidity are enriched using Stringent Tetramer- Associated Magnetic Enrichment (S- TAME) and expanded in vitro (R for “enriched population”, subscript n for round of mutation/selection). Enriched cells are separated by FACS into tetramer positive- staining (R+) and tetramer negative- staining (R-) populations. Multiple rounds of mutation/selection can be performed successively as indicated. (B) Staining of A2Ab-expressing HEK 293 cells with 4A2-tetramers or 3A2/1B7 tetramers as marked after 3 successive transfections for CRISPR-X mutagenesis. Results shown are before the S-TAME step. (C) Staining of cells with tetramer 3A2/1B7 after S-TAME. Results are shown for cells transfected with dCas9, sgRNAs and MS2 AID*D (R1 cells, left panel), AID*D alone (middle panel) and sgRNA alone (right panel). (D) Cells from the R1 population staining positive with the 3A2/1B7 tetramer were isolated by FACS (R1+ cells). Staining of these cells with tetramers 3A2/1B7 (upper left panel) and 1A2/3B7 (upper right panel) is shown. R1+ cells were subjected to a second round of mutagenesis, S-TAME and FACS selection to generate R2+ cells. Staining of R2+ cells with tetramers 3A2/1B7 (lower left panel) and 1A2/3B7 lower right panel) is shown. The number of cells within marked gates is shown between brackets as a percentage of the total cells analysed.

Figure 3: Web Logo representation of amino acid mutations in the A2Ab heavy chain. WT: starting sequence. R1+, R2+: sequences after one or two rounds of mutation/selection respectively. The height of each letter is proportional to the preference for that amino acid at that site, and letters are colored by amino-acid hydrophobicity. Residue positions are numbered starting from the first amino acid of the leader peptide of the heavy chain. Major mutation sites are indicated by arrows.

Figure 4: Characterization of evolved antibodies against HLA-A2. (A) ELISA dose- response curves of R2+ mutated mAbs C4.4 and C4.18 compared to A2Ab. (B) The affinity of C4.18 was measured by surface plasmon resonance by flowing various concentrations of pp65- A2 complex over CM5 chip-bound C4.18. (C) Top panel : staining of 721 221 cells which either express HLA-A2 (721 221(A2)) or do not express it (721 221) by A2Ab, C4.4 and C4.18 at 20pg/mL. MFI are indicated. Lower panel: dose response staining of A2Ab, C4.4 and C4.18 against BLCL HEN expressing HLA-A2. MFI obtained with various concentrations of C4.18 and C4.4 are indicated. (D) The specificity of mutated R2+ mAbs was assessed in a Luminex single antigen bead assay. Results are shown in terms of interval MFI. Positivity threshold was set at 1000.

EXAMPLE:

Methods:

Donors

Human peripheral blood samples were obtained from anonymous adult donors after informed consent in accordance with the local ethics committee (Etablissement Francais du Sang, EFS, Nantes, procedure PLER NTS-2016-08).

Cell lines and culture conditions

Human embryonic kidney 293A cells were obtained from Thermo Fisher Scientific, San Jose, CA, USA (R70507). Cells were grown as adherent monolayers in DMEM (4.5g/l glucose) supplemented with 10% FBS, 1% Glutamax (Gibco) and 1% penicillin (10 000U/ml)/streptomycin (10 OOOU/ml) (a mixture from Gibco). The BLCL cell lines HEN (HLA-A*0201/ HLA-A*0101), B721 221 and stably transfected HLA-A2 B721 221 (B721 221 A2) were grown in suspension in RPMI medium supplemented with 10% FBS, 1% Glutamax (Gibco) and 1% penicillin (10 000U/ml)/streptomycin (10 OOOU/ml) (a mixture from Gibco).

Plasmid constructions

Plasmids for mutagenesis were obtained from Addgene : pGH335_MS2-AID*A-Hygro (catalogue n° 85406), pX330S-2 to 7 from the Multiplex CRISPR/Cas9 Assembly System kit (n° 1000000055) and pX330A_dCas9-lx7 from the multiplex CRISPR dCas9/Fok-dCas9 Accessory pack (n° 1000000062). The sgRNA scaffolds in the seven latter plasmids were replaced by the sgRNA_2MS2 scaffold from pGH224_sgRNA_2xMS2_Puro (Addgene n° 85413) and guide sequences then introduced into their Bbsl sites before Golden Gate assembly. SgRNA design was performed online using Sequence Scan for CRISPR software (http://crispr.dfci.harvard.edu/SSC/). Final plasmids for mutagenesis thus obtained contain expression cassettes for dCas9 and seven sgRNAs. For production of antibodies, VH and VL regions from human antibodies were subcloned respectively in an IgG-Abvec expression vector (FJ475055) and an Iglambda -AbVec expression vector (FJ51647) as previously described[8]. For mammalian display of antibodies as IgGl, VH and VL regions were subcloned into home made expression vectors derived from the OriP/EBNAl based episomal vector pCEP4. The VH and VL expression vectors contain a hygromycin B or Zeocin resistance marker respectively, and a transmembrane region encoding sequence exists in the C gamma constant region sequence.

IgGl mammalian cell display

Heavy and light chain expression vectors were co-transfected into the 293A cell line at a 1: 1 ratio using JetPEI (PolyplusTransfection, Cat. 101-10N) and cultured for 48 h. Selection of doubly transfected cells was performed using Hygromycin B and Zeocin. Antibody surface expression on the selected cells was confirmed by flow cytometry analysis after staining with a PE-labeled goat-anti-human IgG Fc (Jackson ImmunoResearch).

Peptide MHC Tetramer

The HLA-A*0201-restricted peptides Pp65₄₉₅ (human CMV [HCMV], NLVPMVATV) and MelA27 (melanoma Ag, ELAGIGILTV) and the HLA-B*0702-restricted UV-sensitive peptide (AARGJTLAM; where J is 3-amino-3-(2-nitro)phenyl-propionic acid) were purchased from GL Biochem (Shanghai, China). Soluble peptide MHC monomers used in this study carried a mutation in the a3 domain (A245V), that reduces CD8 binding to MHC class I. Biotinylated HLA-A*0201/MelA₂₇ (HLA- A2/MelA) , HLA-A*0201/Pp65₄₉₅ (HLA- A2/Pp65), HLA-B*0702/UV sensitive peptide (HLA-B7/pUV) monomers were tetramerized with allophycocyanin (APC)-labeled premium grade streptavidins (Molecular Probes, Thermo Fischer Scientific, ref S32362) at a molar ratio of 4: 1. Where applicable, the avidity of the tetramer for its specific antibody was decreased by mixing specific (ie peptide HLA-A2) and unspecific (ie peptide UV-sensitive HLA-B7) biotinilated monomers before tetramerization with APC-labeled streptavidins at different molar ratios.

Flow cytometry analysis

The specificity and avidity of IgG expressing HEK 293 cells was analysed by flow cytometry. Cells were first stained in PBS containing 0.5% BSA with Ag tetramers for 30 min at room temperature. Anti-PE human IgG was then added at a 1/500 dilution for 15 mn on ice without prior washing. The binding of mutant antibodies was evaluted on 150 000 BLCL cells. Cells were incubated with various concentrations of large-scale purified mAbs diluted in 25ml of PBS containing 0.5% BSA for 30 min at room temperature. Anti-PE goat anti-human IgG was then added at a 1/500 dilution for 15 min on ice without prior washing.

Mutagenesis

4xl0⁶ anti HLA-A2 IgG-expressing cells were seeded the day before transfection in a 175 cm flask. For each round of mutation, cells were transiently transfected using JET-PRIME (PolyplusTransfection, Cat. 101-10N) with pGH335_MS2-AID*A-Hygro together with two other plasmids allowing expression of a total of 9 different sgRNAs along with dCas9 at a ration 1 : 1 : 1.

Affinity-based cell selection and immunomagnetic enrichment

After a round of mutagenesis, transfected cells were expanded until confluency over a week. For selection, 10-20xl0⁶ cells were washed, resuspended in 0.2 mL of PBS containing 2% BSA and the antigen (i.e. APC HLA-A2 tetramers or mixed APC HLA-A2/HLA-B7 tetramers) and incubated for 30 min at room temperature. The tetramer-stained cells were then positively enriched using APC Ab-coated immunomagnetic beads and columns as previously described[8]. The resulting enriched fraction was stained with an anti human IgG-PE. IgG PE+and tetramer APC+ were collected on an ARIA cell sorter. The adopted strategy for evolution of mAb A2Ab was as follows: 1) three rounds of mutagenesis; 2) magnetic enrichment with 3A2/1B7 tetramer; 3) FACS sorting of positive cells. Positively selected and sorted mutated HEK 293 underwent two new rounds of mutation using the same sgRNAs before selection with the 1A2/3B7 tetramer.

Antibody production

Small and large scale productions were performed as previously described⁸.

ELISA

HLA-A2/Pp65 monomers were coated O/N at 4 °C in 100 pL of reconstituted ELISA/ELISPOT coating buffer IX (Affymetrix) at a final concentration of 2 pg/mL in 96- well ELISA plates (Maxisorp, Nunc). Wells were blocked with 10% FBS DMEM medium (Thermo Fischer Scientific) for 2 h at 37 °C. Purified mAbs were serially diluted in PBS (starting concentration: lOOpg/ml ; dilution factor: 3) and incubated for 2 h at RT. An anti human IgG-HRP Ab (BD Biosciences) was used at 1 pg/mL for detection after incubation for 1 h at RT. The reaction was visualized by the addition of 50 pL chromogenic substrate (TMB, BD biosciences) for 20 min. ODs were read at 450 nm.

Anti-HLA Antibody Testing (Luminex) The specificity analysis of the antibody variants was performed using Single Antigen Flow Bead assays according to the manufacturer's protocol (LabScreen single-antigen LS 1A04, One Lambda, Inc., Canoga Park, CA), exploring 97 class I alleles. The fluorescence of each bead was detected by a Luminex 100 analyser (Luminex, Austin, TX), and recorded as the mean fluorescence intensity (MFI). The positivity threshold for the bead MFI was set at 1000 after removal of the background as previously reported[25]. Clinical relevance of pre-transplant donor- specific HLA antibodies was detected by single- antigen flow-beads.

Surface Plasmon Resonance

Surface Plasmon Resonance (SPR) experiments were performed at 25°C on a Biacore 3000 apparatus (GE Healthcare Life Sciences, Uppsala, Sweden) on CM5 sensorchips (GE Healthcare). Capture mAbs were immobilized at 10mg/mL by amine coupling using a mixture of N-hydroxysuccinimide and N-ethyl-N'-dimethylaminopropyl carbodiimide, according to the manufacturer’s instructions (GE Healthcare), after a 20-fold dilution in lOmM sodium acetate buffer pH 5. Then, ethanolamine (1M, pH 8.5, GE Healthcare) was injected to deactivate the sensor chip surface. Purified HLA-A*0201 molecules containing the Pp65₄₉₅ peptide were injected at various dilutions over the capture antibodies for 180s at 40pL/min. A flow cell left blank was used for referencing of the sensorgrams.

Bioinformatics analysis

Amplicon preparation: total RNA was purified from 5xl0⁶ HEK 293 cells and 1 pg of total RNA was reverse transcribed using Superscript reverse transcriptase (ThermoFisher). cDNA was subsequently amplified using Q5 DNA polymerase and primers targeting VH sequences. Sense and antisense primers include target sequences suitable for nextera indexage. Barcodes were further introduced by PCR with indexed nextera and the amplicons were sequenced at the IRICs Genomics Core Facility at Montreal. Paired-end MiSeq technology (Miseq Reagent Nano kit v2 (500 cycles) from Illumina, Inc. San Diego, CA, USA) was used, with a 2 x 250 bp setup.

Pretreatment and sequence clustering

For each chip generated, approximately one million reads were obtained for all the samples. The quality and length distribution of the reads were checked using the FASTQ tool (vO.11.7). After that, for each sample, the paired-end sequences were assembled using the PEAR software (vO.9.6) while keeping only the sequences whose Phred score was greater than 33 and whose overlap was at least 10 nucleotides. Then 30000 sequences were randomly selected to normalize samples. Next, for each sample, full length VH sequences were grouped according to their identity and counted and clusters were formed as described in the text. Mutations observed in the mock control (gRNA only) experiment were then eliminated in order to distinguish site-directed mutations from RT-PCR or sequence errors. Only clusters representing more than 0.1% of the total number of sequences were retained.

Alignment and mutation analysis

For each sample, the generated clusters were annotated by aligning each sequence cluster against the reference sequence using Biostring library (v2.48.0) in a custom R script, to generate a counting table. The generated data were filtered by subtracting the mutations detected in the mock sample. A position matrix was then generated to create a Weblogo using the ggseqlogo library (vO. l). All statistical analyses were performed in a custom R script.

Results:

Isolation of a low affinity human antibody against HLA-A*0201

A human HLA-A*0201 molecule (hereafter referred to as HLA-A2) was selected as a target for antibody discovery and maturation as it is easy to obtain blood samples from donors not previously immunized against this MHC allele. In addition, various recombinant HLA molecules were readily available in our laboratory. PBMCs from three HLA-A2-negative donors with negative serology for HLA-A2 circulating antibodies were tested for the presence of blood circulating B cells specific for HLA-A2. This was done by flow cytometry sorting of B cells that bound HLA-A2 tetramers labeled with two different fluorochromes but did not bind HLA-B7 tetramers, using a technique described previously [8, 10]. B lymphocytes stained specifically by HLA-A2 tetramers could be identified in PBMC from all three donors (see Figure 1A for an example) and were isolated as single cells. We attempted RT-PCR amplification of sequences coding for the variable regions of the heavy and light chains of four B lymphocytes isolated from one donor (NO) using a recently published protocol [8, 10]. A pair of heavy and light chain V region coding sequences was obtained for one of the four cells. After cloning these gene segments into eukaryotic expression vectors in phase with human heavy and light chain constant domains, the corresponding antibody (ma) was successfully produced in the supernatant of transfected HEK cells and tested for its specificity. A2Ab recognizes HLA-A2 but not HLA-B7 in ELISA tests and this recognition does not depend on the peptide loaded into the HLA pocket (Figure IB). A single HLA antigen flow bead assay analysis confirmed that A2Ab can recognize HLA-A*0201, but also showed that A2Ab recognizes closely related alleles belonging to the HLA-A*02 supertype (HLA-A*0203, A*0206 and A*6901) and weakly cross-reacts with other MHC A alleles. However, B or C alleles are not recognized (data not shown, results summarized in Figure 1C). Finally, the affinity of A2Ab for the pp65/HLA-A2 complex was determined by surface plasmon resonance (SPR) to be in the low micromolar range (Kd = 8.10 ⁶, Figure ID). This is consistent with the HLA-A2- specific B cells being isolated from a naive/non-immune blood circulating B cell repertoire.

CRISPR-X targeted mutagenesis of A2Ab and screening for higher avidity antibodies

We used the CRISPR-X approach [24] to mutate the A2Ab sequence. Our overall procedure using iterative mutation and selection is summarized in Figure 2A. HEK 293 cells were engineered to express cell surface A2Ab by stable transfection of episomal vectors expressing its heavy and light chains (HC and LC, respectively). For induction of mutations, these cells were then transiently transfected with a plasmid coding for AID*A fused to MS2 coat protein, and plasmids coding for dCas9 and nine different sgRNAs spanning the sequence coding for the A2Ab HC variable domain. AID* A is an AID mutant with increased SHM activity whose Nuclear Export Signal (NES) has been removed [24]. It has significantly increased mutation activity compared to wild-type AID without a NES [24]. Three successive transient transfections were performed before cells were screened for expression of mutant antibodies with increased avidity for HLA-A2.

Cells we started from stably expressed cell surface A2Ab and thus were able to bind tetramers comprising four HLA-A2 molecules. These cells were subjected to three successive transfections. We expected cells expressing higher avidity antibodies post-mutagenesis to be able to bind tetramers containing fewer HLA-A2 molecules. We thus sought to identify cells in the mutated polyclonal population using labeling with a tetramer made up of 3 HLA-A2 molecules and one B7 molecule (3A2/1B7). As shown in Figure 2B, we were unable to detect any 3A2/lB7-labeled cells in the mutated polyclonal population by flow cytometry, while all cells expressing IgG were labeled with the initial tetramer (4A2) as expected.

We suspected that 3A2/lB7-labeled cells might be too rare to be detectable in the fraction of the mutated polyclonal population we tested, so we tried to enrich them before analysis. The mutated poylconal population was first incubated with the 3A2/1B7 tetramer coupled to APC, then subjected to positive selection using paramagnetic beads coupled to anti- APC antibodies. After magnetic enrichment, we observed a small proportion of cells clearly labeled by the 3A2/1B7 tetramer (Figure 2C, left dot-plot). Notably, no such cells were detected when our protocol was carried out using A2Ab-expressing HEK 293 cells transfected with a hyperactive non-guided AID (Figure 2C, middle dot-plot), or with guide RNAs alone (“mock”, Figure 2C, right dot-plot). This first“positive” population (Rl) was purified by cell sorting and expanded in vitro to yield population R1+ (>95% pure). In marked contrast to the starting population, the R1+ population bound tetramers with just 3 HLA-A2 molecules (3A2/1B7, Figure 2D, upper left dot-plot).

To complete a further round of mutagenesis/selection, we exposed the R1+ population to two successive transfections for mutagenesis using the same batch of sgRNAs as above, before selection was performed. This time we used a more stringent enrichment process with tetramers containing only one HLA-A2 molecule (1A2/3B7). A new population of tetramer positive cells was obtained (R2+), with a 2.2 fold increase in the 3A2/1B7 tetramer mean fluorescence intensity compared to R1+ (Figure 2D, bottom left dot-plot). The R2+ population was also stained by tetramer 1A2/3B7, in marked contrast to R1+ cells (Figure 2D, compare upper and lower right dot-plots). Each round of mutation and selection thus increases the avidity of the antibodies.

Antibody sequence evolution during mutagenesis and selection rounds

As described above, we were unable to detect cells capable of binding to the 3A2/1B7 tetramer after one round of mutagenesis until we used magnetic enrichment. This enrichment generated the R1 population. FACS sorting of this population yielded the R1+ population capable of binding 3A2/1B7 tetramers and the Rl- population incapable of binding this tetramer. We used next generation sequencing (NGS) to search for heavy chain sequences enriched in the R1+ population relative to the Rl- population and which could contain mutations responsible for the increased affinity of the R1+ population antibodies. 30,000 randomly selected reads from each population were analyzed. Reads represented more than 50 times were placed into a read-specific cluster, while reads represented less than 50 times were grouped together in a category we termed“small clusters”. For the R1+ population, two large clusters representing together 42.5% of reads were detected, in addition to a third large cluster representing WT sequences (Table I). Six other clusters representing together 5.2% of reads were also detected, together with numerous reads in the small cluster category. Seven of these eight non-WT clusters were clearly under-represented in the Rl- population, where the WT cluster and small clusters predominated. Mutations observed in the seven clusters were located in the FR3 and CDR3 regions (Figure 3). They were often shared between different clusters, suggesting that they contribute to the increased affinity of R1+ population antibodies.

That WT and small cluster sequences represent 52.6% of R1+ reads might seem surprising. However, in the HEK 293 cells subjected to mutagenesis, antibody genes are present on episomal vectors, with several vector copies per cell [26]. Cells selected with the 3A2/1B7 tetramer may contain only one gene copy with a mutation leading to an antibody of increased affinity. All the other copies could contain either no mutation or neutral or even deleterious mutations, yet they will be co-enriched with the copy carrying the affinity-increasing mutation.

The second round of mutation/selection led to a drastic decline in WT reads (from 13.6% for R1+, to 0% for R2+), while in the R2+ population a cluster representing nearly half of the NGS reads emerged, corresponding to HCs accumulating six mutated amino acids: D74H/S80T/W102L/M112I/G121D/R124P (Table II, Figure 3). Interestingly, the CDR2 D74H mutation was not detected in the R1+ population. Nine of the thirteen R2+ clusters (a cluster contains more than 50 reads of the cluster- specific sequence) differ only very slightly from this main sequence, underlining a strong convergence of most of the R2+ clusters. The W102, Ml 121, G121D and R124P mutations were already well represented in the R1+ population (Table I). The second round of mutation/selection led to emergence of two new R2+-specific mutations: D74H in the CDR2 and S80T in the FR3 region.

Characterization of evolved antibodies against HLA-A2

The R2+ antibodies C4.4 and C4.18 (Tables I and II) were produced as recombinant proteins for comparison of their affinity and specificity to those of the initial A2Ab. As shown in Figure 4A, C4.4 and C4.18 mAbs show clearly increased reactivity against HLA-A*0201 compared to A2Ab in an ELISA. We next determined C4.18's affinity for HLA-A*0201 by SPR: Kd=10 ⁷ (Figure 4B). This is an almost two log increase over that of the initial A2Ab (Kd=8xl0 ⁶). We were unable to make enough C4.4 for SPR studies.

These results demonstrate that our matured antibodies bind with higher affinity to antigen than A2Ab in fully in vitro tests. But can they bind to antigen expressed on the surface of cells, a prerequisite for biological activity? The initial A2Ab was not of sufficient affinity to bind to two HLA-A2 expressing cell lines tested, 721.221 B cells made HLA-A2 positive by transfection (721.221(A2)), and naturally HLA-A2 expressing BLCL HEN. However, the increased affinity of C4.4 and C4.18 led to ready detection of such binding (Figure 4C). Binding to 721.221(A2) B cells was HLA-A2 dependent, as no binding was observed to the parental HLA-A2 negative 721.211 B cells. A single HLA antigen flow bead assay analysis confirmed that C4.4 and C4.18 had higher affinity than A2Ab for HLA-A*0201 and also showed a gain in specificity, as they had significantly less crossreactivity against other HLA-A alleles (compare Figure 4D to Figure 1C).

Discussion:

We show that starting from a low affinity antibody, CRISPR-X targeting of AID to antibody genes can be used to obtain affinity-matured human antibodies in cellulo in about 6 weeks. Thus we increased the affinity of a fully human anti-HLA-A*0201 mAh to sufficient levels for biological activity and without loss of specificity in just 2 cycles of mutation/selection (each cycle consisting of several successive mutagenesis transfections prior to the selection steps). The low affinity antibody we started from was expressed by naive B cells. Our procedure thus mimics in vitro antibody maturation in secondary lymphoid organs, where naive B lymphocytes stimulated by Ag recognition via specific BCRs of limited affinity go on to generate receptors optimized for Ag recognition.

The fully human mAbs specific for the HLA-A*0201 allele we generated could have direct clinical applications, notably in the context of mismatch HLA-A2 organ transplantation. Two recent studies described the efficacy of anti-HLA-A2- specific CARs of murine origin in the control of graft rejection in animal models [35, 36]. Using fully human antibodies could be an important step forward for implementation of such strategies to humans.

TABLES:

Table I : CRISPR-X-mediated evolution of A2Ab : NGS analysis, round 1

R1

Cluster name mAb name %R1+ (counts) %R1- (counts)

total 100 (30000) 100 (30000) Table II : CRISPR-X-mediated evolution of A2Ab : NGS analysis, round 2

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Claims

CLAIMS:

1. A human monoclonal antibody that comprises: a heavy chain comprising i) the H-CDR1 as set forth in SEQ ID NO:3, ii) the H- CDR2 as set forth in SEQ ID NO:4 and iii) the H-CDR3 as set forth in SEQ ID NO:5, and, a light chain comprising i) the L-CDR1 as set forth in SEQ ID NO:6, ii) the L- CDR2 as set forth in SEQ ID NO:7 and iii) the L-CDR3 as set forth in SEQ ID NO:8.

2. The human monoclonal antibody of claim 1 that comprises a VH domain consisting of the amino acid sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 144 in SEQ ID NO:l.

3. The human monoclonal antibody of claim 1 that comprises a VH domain characterized by the presence of mutations as depicted in Table I or II.

4. The human monoclonal antibody of claim 1 that comprises a VH domain of the amino acid sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 144 in SEQ ID NO:l comprising at least one mutation selected from the group consisting of: the (D) residue at position 74 in SEQ ID NO: 1 is substituted by a (H) residue the (S) residue at position 80 in SEQ ID NO: 1 is substituted by a (T) residue) - the (W) residue at position 102 in SEQ ID NO:l is substituted by a (L) residue the (M) residue at position 112 in SEQ ID NO: 1 is substituted by a (I) residue the (G) residue at position 121 in SEQ ID NO:l is substituted by a (D) residue and, the (R) residue at position 124 in SEQ ID NO:l is substituted by a (P) residue.

5. The human monoclonal antibody of claim 1 that comprises a VH domain of the amino acid sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 144 in SEQ ID NO:l wherein: the (D) residue at position 74 in SEQ ID NO: 1 is substituted by a (H) residue - the (S) residue at position 80 in SEQ ID NO: 1 is substituted by a (T) residue) the (W) residue at position 102 in SEQ ID NO:l is substituted by a (L) residue the (M) residue at position 112 in SEQ ID NO: 1 is substituted by a (I) residue the (G) residue at position 121 in SEQ ID NO:l is substituted by a (D) residue the (R) residue at position 124 in SEQ ID NO:l is substituted by a (P) residue.

6. The human monoclonal antibody of claim 1 that comprises a VH domain of the amino acid sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 144 in SEQ ID NO:l wherein: the (D) residue at position 74 in SEQ ID NO: 1 is substituted by a (H) residue the (W) residue at position 102 in SEQ ID NO:l is substituted by a (L) residue - the (M) residue at position 112 in SEQ ID NO: 1 is substituted by a (I) residue the (G) residue at position 121 in SEQ ID NO:l is substituted by a (D) residue the (R) residue at position 124 in SEQ ID NO:l is substituted by a (P) residue.

7. The human monoclonal antibody of claim 1 that comprises a VL domain consisting of the sequence ranging from the amino acid residue at position 20 to the amino acid residue at position 133 in SEQ ID NO:2.

8. A nucleic acid sequence encoding the human monoclonal antibody of claim 1.

9. A nucleic acid sequence that encodes a heavy chain and/or a light chain of the human monoclonal antibody of claim 1.

10. A vector that comprises the nucleic acid sequence of claim 8 or 9.

11. A host cell which has been transfected, infected or transformed by the nucleic acid of claim 8 or 9 and/or the vector of claim 10.

12. A chimeric antigen receptor (CAR) comprising an antigen binding domain of the monoclonal antibody of claim 1.

13. The CAR of claim 12 comprising an antigen-binding domain comprising, consisting of, or consisting essentially of, a single chain variable fragment (scFv) of the monoclonal antibody of claim 1.

14. A nucleic acid encoding for the chimeric antigen receptor of claim 12.

15. A host cell engineered to express the chimeric antigen receptor (CAR) of claim 12.

16. The host cell of claim 15 that is a T cell, a pluripotent stem cell, or a hematopoietic stem cell

17. The host cell of claim 15 that is a Treg cell.

18. Use of a population of host cells according to claim 15 in adoptive immunotherapy.

19. A method of preventing or suppressing an immune response associated with rejection of a donor tissue, cell, graft, or organ transplant by a recipient subject comprising administering the subject with the population of host cells according to claim 15.

20. A method of preventing GVHD in a subject in need thereof comprising administering to the subject the population of host cells according to claim 15.