WO2019122875A1

WO2019122875A1 - Chimeric antigen receptor

Info

Publication number: WO2019122875A1
Application number: PCT/GB2018/053691
Authority: WO
Inventors: Martin PULÉ; Gordon Weng-Kit CHEUNG; Kerry Chester
Original assignee: Ucl Business Plc
Priority date: 2017-12-20
Filing date: 2018-12-19
Publication date: 2019-06-27
Also published as: GB201721421D0

Abstract

The present invention relates to a chimeric antigen receptor comprising a disulphide bond between the VH and VL domains. The present invention also provides engineered cells, pharmaceutical compositions and pharmaceutical compositions for use in the treatment and/or prevention of disease.

Description

CHIMERIC ANTIGEN RECEPTOR

FIELD OF THE INVENTION

The present invention relates to a chimeric antigen receptor (CAR) and to cells comprising said CAR; and in particular to approaches to improve the activity and/or persistence of such cells in a recipient and to reduce associated toxicity. The present invention relates to pharmaceutical compositions comprising the cells in accordance with the present invention and their use in treating and/or preventing a disease.

BACKGROUND TO THE INVENTION

Standard immunotherapy approaches include therapeutic monoclonal antibodies (mAb), bi specific T cell engagers (BiTES) and immune-conjugates and radio-conjugates. Adoptive cell therapy is a personalised therapy which comprises administration of immune cells with specific activity towards a disease related antigen.

Antigen-specific T cells have been generated by selected expansion of peripheral blood T cells natively specific for the target antigen. These calls may also be called tumour-infiltrating lymphocytes (TILs). The utility of TILs has been demonstrated in melanoma. However, it is has been difficult to select and expand large numbers of T cells specific for cancer antigens in other diseases.

Gene therapy provides a potential solution to this problem. For example, the introduction of chimeric antigen receptors (CARs) or transgenic T cell receptors (TCRs) to cells allows the generation of large numbers of cells specific to an antigen by ex vivo introduction of the nucleic acid encoding the CAR to peripheral blood cells e.g. peripheral blood T cells

CARs are artificial receptors that can be constructed by linking the variable regions of the antibody heavy (VH) and light chains (VL) to intracellular signalling chains alone or in combination with other signalling moieties. CARs recognise antigens which are presented on the tumour cell surface. The antigens do not need to be MHC-restricted. CARs against the B cell antigen CD19 have been successful in mediating regression of an advanced B cell lymphoma.

However, CAR-engineered cells also have the capacity to elicit expected and unexpected toxicities including: cytokine release syndrome, neurologic toxicity, “on target/off tumour” recognition, and anaphylaxis. Abrogating toxicity has become a critical step in the successful application of this emerging technology. Some engineered CAR cells exhibit levels of basal signalling which lead to chronically exhausted engineered cells which cannot persist in vivo. There remains a need for improved CAR-engineered cells which provide enhanced safety and/or reduced toxicity. SUMMARY OF ASPECTS OF THE INVENTION

The present invention is based, at least in part, on the inventors’ determination that introducing disulphide bonds between the VH and VL domains of a CAR may improve performance of the CAR.

In particular, the present inventors have determined that the introduction of a disulphide bond between the VH and VL domains of a CAR reduces basal signalling. Without wishing to be bound by theory, cells comprising the CAR according to the present invention may have decreased immune toxicity and/or improved specificity against target cells.

The introduction of a disulphide bond between the VH and VL domains of a CAR according to the present invention reduces exhaustion of the cell comprising said CAR. Wthout wishing to be bound by theory, the CARs of the present invention may have improved persistence in vivo. The CAR cells according to the present invention thereby may provide improved engineered cells for use as therapeutics.

The present invention provides a chimeric antigen receptor (CAR) comprising a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VH and scFv VL to form a disulphide single chain variable fragment (dsscFv).

Suitably, the present invention may provide a chimeric antigen receptor (CAR) having a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VH and scFv VL to form a disulphide single chain variable fragment (dsscFv).

Suitably, the present invention may provide a chimeric antigen receptor (CAR) consisting of a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VH and scFv VL to form a disulphide single chain variable fragment (dsscFv).

The CAR may comprise the general format dsscFv-spacer-transmembrane domain-signalling domain.

The CAR may comprise a first chain comprising the general format VH-spacer-transmembrane domain-signalling domain and a second chain having the general format VL-spacer- transmembrane domain-signalling domain wherein one or more disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

The CAR may comprise a first chain having the general format VH-spacer-transmembrane domain-signalling domain and a second chain having the general format VL-spacer- transmembrane domain-signalling domain wherein one or more disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

The CAR may comprise a first chain comprising a VH or VL domain and a transmembrane domain and a second chain comprising a VL or VH domain, wherein the second chain is secreted and wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

The CAR may comprise a first chain having the general format VH or VL-spacer- transmembrane domain-signalling domain and a second chain comprising a VL or VH, wherein the second chain is secreted and wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

The CAR may comprise the general format dsscFv-CD3.

The CAR may comprise the general format TCR element-transmembrane domain-signalling domain.

The CAR may be a multi-span protein.

The CAR may comprise a split receptor such that the antigen recognition domain is a separate protein from the signalling domain.

The one or more disulphide bonds may be between framework regions.

The one or more disulphide bonds may be between complementarity determining regions (CDRs).

The one or more disulphide bonds may be between positions 44 VH FR2 and position 100 in VL FR4.

The one or more disulphide bonds may be between positions 105 VH FR4 and position 43 in VL FR2.

In another aspect, the present invention provides a polynucleotide which encodes a CAR according to the present invention.

In one aspect, there is provided a nucleic acid construct which comprises a nucleic acid sequence which encodes a CAR according to the present invention.

In one aspect, there is provided a nucleic acid construct having a nucleic acid sequence which encodes a CAR according to the present invention.

In another aspect, the present invention provides a vector which comprises a polynucleotide which encodes a CAR according to the present invention or which comprises a nucleic acid construct which comprises a nucleic acid sequence which encodes a CAR according to the present invention.

In another aspect, the present invention provides a vector having a polynucleotide which encodes a CAR according to the present invention or having a nucleic acid construct which encodes a CAR according to the present invention.

In another aspect, the present invention provides an engineered cell comprising said chimeric antigen receptor (CAR) according to the present invention.

Suitably, the present invention may provide an engineered cell having (e.g. expressing) said chimeric antigen receptor (CAR) according to the present invention.

In a further aspect, the present invention provides a pharmaceutical composition which comprises a cell according to the present invention.

In a further aspect, the present invention provides a pharmaceutical composition having (e.g. including) a cell according to the present invention.

In one aspect, the present invention provides a pharmaceutical composition according to the present invention for use in treating and/or preventing a disease. In another aspect, the present invention provides a method for treating and/or preventing a disease, which comprises the step of administering a pharmaceutical composition according to the present invention to a subject in need thereof.

In another aspect, the present invention provides a method for treating and/or preventing a disease, having the step of administering a pharmaceutical composition according to the present invention to a subject in need thereof.

In another aspect, the present invention provides a method for treating and/or preventing a disease, consisting of the step of administering a pharmaceutical composition according to the present invention to a subject in need thereof.

In a further aspect, the present invention provides a use of a pharmaceutical composition according to the present invention in the manufacture of a medicament for the treatment and/or prevention of a disease.

In another aspect, the present invention provides a method for making a cell which comprises transducing or transfecting a cell with a polynucleotide according to the present invention, or a nucleic acid construct according to the present invention, or a vector according to the present invention.

In a further aspect, the present invention provides a method for enhancing the stability of a CAR by introducing a cysteine residue into the VH domain and a cysteine residue into the VL domain.

DESCRIPTION OF THE FIGURES

Figure 1 - shows a schematic diagram of chimeric antigen receptors with standard scFv’s which do not comprise a disulphide bond according to the present invention. Concatenation of standard CARs can occur due to interactions of VH/VL from different receptors. This concatenation can cause aggregation and exclusion of inhibitory phosphatases such as CD45 and CD148. As a result, the CAR T-cell can activate in the absence of cognate antigen. Artificial disulphide bonds introduced between the VH/VL according to the present invention can restrict interaction of VH/VL of each CAR and prevent concatenation and basal activity.

Figure 2 - shows a schematic diagram of one embodiment of the present invention, wherein disulphide stabilized domains which can pair correctly in the absence of a physical linker between the heavy and light chains. Functional CARs can be obtained through tethering of one antibody variable chain to a spacer and transmembrane domain and allowing the other to be secreted into the extracellular space. Both chains may also be tethered to the cell; this configuration provides a format to split co-stimulation on a single CAR.

Figure 3 - shows a schematic diagram of one embodiment of the present invention, demonstrating the structural basis of disulphide bond stability enhancement. The heavy (grid) and light (dotted) chains of an antibody fragment variable are shown. The structure is displayed in the absence and presence of cysteine residues at position 100 of the VH and 44 of the VL. The two cysteine residues are capable of forming a disulphide bond thus stabilizing the molecule.

DETAILED DESCRIPTION CHIMERIC ANTIGEN RECEPTOR (CAR)

A classical chimeric antigen receptor (CAR) is typically a chimeric type I trans-membrane protein which connects an extracellular antigen-recognizing domain (binder) to an intracellular signalling domain(s) (endodomain) (Figure 1). The binder is typically a single-chain variable fragment (scFv) derived from a monoclonal antibody (mAb), but it can be based on other formats which comprise an antibody-like antigen binding site. A spacer domain is usually used to isolate the binder from the membrane and to allow it to position itself in a suitable orientation. A common spacer domain used is the Fc of lgG1. More compact spacers can suffice such as the stalk from CD8a or even just the lgG1 hinge alone, depending on the antigen. A trans membrane domain anchors the protein in the cell membrane and connects the spacer to the endodomain.

Early CAR designs had endodomains derived from the intracellular parts of either the g chain of the FcsR1 or Oϋ3z. Consequently, these first generation receptors transmitted immunological signal 1 , which was sufficient to trigger T-cell killing of cognate target cells but failed to fully activate the T-cell to proliferate and survive. To overcome this limitation, compound endodomains have been constructed: fusion of the intracellular part of a T-cell co-stimulatory molecule to that of Oϋ3z results in second generation receptors which can transmit an activating and co-stimulatory signal simultaneously after antigen recognition. The co-stimulatory domain most commonly used is that of CD28. This supplies the most potent co-stimulatory signal - namely immunological signal 2, which triggers T-cell proliferation. Some receptors have also been described which include TNF receptor family endodomains, such as the closely related 0X40 and 41 BB which transmit survival signals. Even more potent third generation CARs have now been described which have endodomains capable of transmitting activation, proliferation and survival signals.

CAR-encoding nucleic acids may be introduced into cells e.g. T cells using, for example, retroviral vectors. Lentiviral vectors may be employed. In this way, a large number of antigen- specific cells can be generated for adoptive cell transfer. When a CAR binds the target-antigen, this results in the transmission of an activating signal to the T-cell it is expressed on. Thus the CAR directs the specificity and cytotoxicity of the T cell towards tumour cells expressing the targeted antigen.

CARs typically therefore comprise: (i) an antigen-binding domain; (ii) a spacer; (iii) a transmembrane domain; and (iii) an intracellular domain which comprises or associates with a signalling domain. Suitably, the CAR according to the present invention may comprise the general format dsscFv- spacer-transmembrane domain-signalling domain. Suitably, the CAR according to the present invention may have the general format dsscFv-spacer-transmembrane domain-signalling domain.

Suitably, the CAR according to the present invention may comprise the general format: antigen binding domain-CD3. Suitably, the CAR according to the present invention may have the general format: antigen binding domain-CD3.

Suitably, the CAR according to the present invention may comprise the general format: dsscFv- CD3. Suitably, the CAR according to the present invention may have the general format: dsscFv-CD3.

Suitably, the CAR according to the present invention may comprise (e.g. have) a first chain having the general format VH-CD3 and a second chain having the general format VL-CD3 wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

Suitably, the CAR according to the present invention may comprise the general format: TCR element-transmembrane domain-signalling domain. Suitably, the CAR according to the present invention may have the general format: TCR element-transmembrane domain-signalling domain.

As used herein“TCR element” means a domain or portion thereof of a component of the TCR receptor complex. The element may be an extracellular domain and/or a transmembrane domain and/or an intracellular domain e.g. intracellular signalling domain.

Suitably the TCR element is selected from an extracellular domain or portion thereof of TCR alpha chain, TCR beta chain, a CD3 epsilon chain, a CD3 gamma chain, a CD3 delta chain, CD3 epsilon chain.

In another aspect, the CAR according to the present invention may comprise an inter-chain disulphide bond. For example, the disulphide bond may be formed between VH and VL domains present on separate chains.

Suitably, a CAR according to the present invention may be comprised of a first chain comprising a VH domain and a second chain comprising a VL domain wherein one or more inter-chain disulphide bonds are present between the VH and VL domains.

Suitably, a CAR according to the present invention may be comprised of a first chain having the general format VH-spacer-transmembrane domain-signalling domain and a second chain having the general format VL-spacer-transmembrane domain-signalling domain wherein one or more inter-chain disulphide bonds are present between the VH and VL domains.

Suitably, a CAR according to the present invention may have the general format as shown in Figure 2.

Suitably, a CAR according to the present invention may comprise a transmembrane domain comprising a VH or VL domain and a second domain comprising a VL or VH domain, wherein the second domain is secreted and wherein one or more inter-chain disulphide bonds are present between the VH and VL domains to form a disulphide stabilised variable fragment (dsFv).

Suitably, a CAR according to the present invention may comprise a transmembrane domain comprising a VH domain and a second domain comprising a VL domain wherein the second domain is secreted and wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

Suitably, a CAR according to the present invention may comprise a transmembrane domain comprising a VL domain and a second domain comprising a VH domain wherein the second domain is secreted and wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

Suitably, a CAR according to the present invention may comprise a transmembrane domain having the general format VH or VL-spacer-transmembrane domain-signalling domain and a second domain comprising VL or VH, wherein the second domain is secreted and wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

Suitably, a CAR according to the present invention may comprise a transmembrane domain having the general format VH-spacer-transmembrane domain-signalling domain and a second domain comprising VL, wherein the VL domain is secreted and wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

Suitably, a CAR according to the present invention may comprise a transmembrane domain having the general format VL-spacer-transmembrane domain-signalling domain and a second domain comprising VH, wherein the VH domain is secreted and wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

ANTIGEN BINDING DOMAIN

The antigen binding domain is the portion of the CAR which recognizes antigen.

Numerous antigen-binding domains are known in the art, including those based on the antigen binding site of an antibody, antibody mimetics, and T-cell receptors. For example, the antigen binding domain may comprise: a single-chain variable fragment (scFv) derived from a monoclonal antibody; a natural ligand of the target antigen; a peptide with sufficient affinity for the target; a single domain antibody; an artificial single binder such as a Darpin (designed ankyrin repeat protein); or a single-chain derived from a T-cell receptor.

In one aspect, the antigen binding domain comprises a scFv.

In another aspect, the antigen binding domain comprises a VH domain provided by a first chain and a VL domain provided by a second chain. The antigen binding domain may comprise a domain which is not based on the antigen binding site of an antibody. For example the antigen binding domain may comprise a domain based on a protein/peptide which is a soluble ligand for a tumour cell surface receptor (e.g. a soluble peptide such as a cytokine or a chemokine); or an extracellular domain of a membrane anchored ligand or a receptor for which the binding pair counterpart is expressed on the tumour cell.

The antigen binding domain may be based on a natural ligand of the antigen.

The antigen binding domain may comprise an affinity peptide from a combinatorial library or a de novo designed affinity protein/peptide.

SPACER DOMAIN

The CAR may comprise a spacer sequence to connect the antigen-binding domain with the transmembrane domain and spatially separate the antigen-binding domain from the endodomain. A flexible spacer allows the antigen-binding domain to orient in different directions to facilitate binding.

The spacer sequence may, for example, comprise an lgG1 Fc region, an lgG1 hinge or a human CD8 stalk or the mouse CD8 stalk. The spacer may alternatively comprise an alternative linker sequence which has similar length and/or domain spacing properties as an lgG1 Fc region, an lgG1 hinge or a CD8 stalk. A human lgG1 spacer may be altered to remove Fc binding motifs.

TRANSMEMBRANE DOMAIN

The transmembrane domain is the sequence of the CAR that spans the membrane.

Suitably, the CAR may be a single-span protein.

Suitably, the CAR may be a multi-span protein.

A transmembrane domain may be any protein structure which is thermodynamically stable in a membrane. This is typically an alpha helix comprising of several hydrophobic residues. The transmembrane domain of any transmembrane protein can be used to supply the transmembrane portion of the invention.

The presence and span of a transmembrane domain of a protein can be predicted by those skilled in the art using bioinformatics tools such as the TMHMM algorithm (http://www.cbs. dtu.dk/services/TMHMM-2.0/). Further, given that the transmembrane domain of a protein is a relatively simple structure, i.e. a polypeptide sequence predicted to form a hydrophobic alpha helix of sufficient length to span the membrane, an artificially designed TM domain may also be used (for example as described in US 7052906 B1 which is incorporated herein by reference).

The transmembrane domain may be derived from CD28, which gives good receptor stability. The transmembrane domain may be derived from a component of the TCR receptor complex. The transmembrane domain may be derived from a TCR alpha chain. Suitably, the transmembrane domain may comprise a TCR alpha chain.

The transmembrane domain may be derived from a TCR beta chain. Suitably, the transmembrane domain may comprise a TCR beta chain.

The transmembrane domain may be derived from a CD3 chain. Suitably, the transmembrane domain may comprise a CD3 chain.

Suitably, the transmembrane domain may be derived from a CD3-epsilon chain. Suitably, the transmembrane domain may comprise a CD3-epsilon chain.

Suitably, the transmembrane domain may be derived from a CD3-gamma chain. Suitably, the transmembrane domain may comprise a CD3-gamma chain.

Suitably, the transmembrane domain may be derived from a CD3-delta chain. Suitably, the transmembrane domain may comprise a CD3-delta chain.

Suitably, the transmembrane domain may be derived from a CD3-zeta chain. Suitably, the transmembrane domain may comprise a CD3-zeta chain.

ACTIVATING ENDODOMAIN

The endodomain is the signal-transmission portion of the CAR. It may be part of or associate with the intracellular domain of the CAR. After antigen recognition, receptors cluster, native CD45 and CD148 are excluded from the synapse and a signal is transmitted to the cell. The most commonly used endodomain component is that of CD3-zeta which contains 3 ITAMs. This transmits an activation signal to the T cell after antigen is bound. CD3-zeta may not provide a fully competent activation signal and additional co-stimulatory signalling may be needed. For example, chimeric CD28 and 0X40 can be used with CD3-Zeta to transmit a proliferative / survival signal, or all three can be used together.

Where a CAR comprises an activating endodomain, it may comprise the CD3-Zeta endodomain alone, the CD3-Zeta endodomain with that of either CD28 or 0X40 or the CD28 endodomain and 0X40 and CD3-Zeta endodomain.

Any endodomain which contains an ITAM motif can act as an activation endodomain.

Suitably, the CAR according to the present invention may be a split receptor, such that the antigen recognition domain is a separate protein from the signalling domain.

The activating endodomain may be a TCR intracellular domain.

Suitably, the activating endodomain may comprise a stimulatory domain from an intracellular signalling domain from a component of the TCR receptor complex.

The activating endodomain may be derived from a component of the TCR receptor complex. The activating endodomain may be derived from a CD3 chain. Suitably, the activating endodomain may comprise a CD3 chain.

Suitably, the activating endodomain may be derived from a CD3-epsilon chain. Suitably, the activating endodomain may comprise a CD3-epsilon chain. Suitably, the transmembrane domain may be derived from a CD3-gamma chain. Suitably, the transmembrane domain may comprise a CD3-gamma chain.

Suitably, the activating endodomain may be derived from a CD3-delta chain. Suitably, the activating endodomain may comprise a CD3-delta chain.

Suitably, the activating endodomain may be derived from a CD3-zeta chain. Suitably, the transmembrane domain may comprise a CD3-zeta chain.

DISULPHIDE BOND

The term“disulphide bond” as used herein refers to a bond formed between the sulfhydryl (SH) side chains of two cysteine residues. In particular, an S- anion from one sulfhydryl group acts as a nucleophile, attaching the side chain of a second cysteine to create a disulphide bond and in the process releases electrons for transfer.

Disulphide bonds provide stability to a protein, decreasing further entropic choices that facilitate folding progression towards the native state by limiting unfolded or improperly folded conformations. The increase in stability of a native structure resulting from the formation of a specific disulphide bond is directly proportional to the number of residues between the linked cysteines. For example, the larger the number of residues in the disulphide loop, the greater the stability provided to the native structure.

Artificial disulphide bonds may be achieved by substituting two residues to cysteines. Suitably, an artificial disulphide bond according to the present invention may be produced by substituting two opposing residues to cysteines, one on a VH domain and one on a VL domain.

Provided that the substitutions do not disrupt the folding of VH/VL, and do not impact cognate binding, and the two residues are in close proximity, then protein disulphide isomerase (PDI) family enzymes in the endoplasmic reticulum will form the disulphide bond.

The selection of residues to substitute to cysteines may be made by any method known in the art. For example, algorithms and software tools which may be used to assist in selecting residues to substitute to cysteines are known in the art. One example of such a tool is the Disulfide by design 2 Webserver: http://cptweb.cpt.wayne.edu/DbD2/: as described in Craig, D. B. & Dombkowskbi, A. A. BMC Bioinformatics 14, 346 (2013), which is incorporated herein by reference.

Suitably, the disulphide bond may be formed between complementarity determining regions (CDRs).

Suitably, the disulphide bond may be formed between framework regions.

Suitably, residues in framework regions which are highly conserved amongst different variable region families may be substituted for cysteines. Such residues suitable for substitution to cysteines are disclosed in Reiter, Y.,et al. Nat. Biotechnol. 14, 1239-1245 (1996) which is incorporated herein by reference. When“position numbers” are used herein, the numbering is made with reference to the Kabat numbering system which is a scheme for the numbering of amino acid residues in antibodies based upon variable regions. This scheme is a widely adopted standard for numbering the residues in an antibody in a consistent manner. It will be understood that this numbering system may also be applied to the domains of a CAR.

Suitably, the disulphide bond may be formed between position 44 in VH FR2 and position 100 in VL FR4.

Suitably, the disulphide bond may be formed between position 105 in VH FR4 and position 43 in VL FR2.

“Fv” as used herein is the minimum antibody fragment which contains a complete antigen binding site.

A two-chain Fv species consists of a dimer of one heavy- and one light-chain variable domain in non-covalent association. In a single-chain species, one heavy- and one light-chain variable domain can be covalently linked by a flexible peptide linker such that the light and heavy chains can associate in a dimeric structure analogous to that of a two-chain Fv species.

“scFv” as used herein means a fusion protein of the variable regions of the heavy (VH) and light chains (VL) of immunoglobulins connected with a short linker such as about 10 to about 25 amino acids. The linker may be rich in glycine to provide flexibility, or serine or threonine for solubility. The linker may connect the N terminus of the VH with the C terminus of the VL or vice versa.

ScFv molecules may be engineered in the VH-VL or VL-VH orientation with a linker varying in size to ensure that the resulting scFv forms stable monomers or multimers. When the linker size is sufficiently small, for example 3 to 12 residues, the scFv cannot fold into a functional monomer. Instead, it associates with another scFv to form a bivalent dimer.

According to the present invention, a disulphide bond may be formed between the VH and VL domains of a CAR.

Suitably, the CAR according to the present invention may comprise an intra-chain disulphide bond. For example, the disulphide bond may be formed between VH and VL domains within the same chain.

Suitably, the antigen binding domain of CAR according to the present invention may be a scFv. Suitably, the disulphide bond may be formed between the VH and VL domains of a scFv of a CAR according to the present invention.

Suitably, the disulphide bond may be formed between the VH and VL domains of a scFv monomer of a CAR according to the present invention.

In on aspect, the present invention relates to a CAR comprising a disulphide single chain variable fragment (dsscFv).

As used herein, “disulphide single-chain Fv (dsscFv)” means a scFv which comprises a disulphide bond between the VH domain and the VL domain. Suitably, the antigen binding domain of the CAR according to the present invention may be a disulphide single chain variable fragment (dsscFv).

Suitably, the CAR according to the present invention may comprise the general format dsscFv- spacer-transmembrane domain-signalling domain. Suitably, the CAR according to the present invention may have the general format dsscFv-spacer-transmembrane domain-signalling domain.

In one aspect, the present invention relates to a CAR comprising a disulphide stabilised variable fragment (dsFv).

As used herein, disulphide stabilised variable fragment“dsFv” means an Fv which is stabilised by a disulphide bond. The disulphide bond is formed between separate proteins.

NUCLEIC ACIDS

As used herein, the term“introduced” refers to methods for inserting foreign DNA or RNA into a cell. As used herein the term introduced includes both transduction and transfection methods. Transfection is the process of introducing nucleic acids into a cell by non-viral methods. Transduction is the process of introducing foreign DNA or RNA into a cell via a viral vector.

As used herein, the terms“polynucleotide” and“nucleic acid” are intended to be synonymous with each other. The nucleic acid sequence may be any suitable type of nucleotide sequence, such as a synthetic RNA/DNA sequence, a cDNA sequence or a partial genomic DNA sequence.

The term“polypeptide” as used herein is used in the normal sense to mean a series of residues, typically L-amino acids, connected one to the other typically by peptide bonds between the a- amino and carboxyl groups of adjacent amino acids. The term is synonymous with "protein".

It will be understood by a skilled person that numerous different polynucleotides and nucleic acids can encode the same polypeptide as a result of the degeneracy of the genetic code. In addition, it is to be understood that skilled persons may, using routine techniques, make nucleotide substitutions that do not affect the polypeptide sequence encoded by the polynucleotides described here to reflect the codon usage of any particular host organism in which the polypeptides are to be expressed.

The present invention provides a polynucleotide which encodes a CAR according to the present invention.

The present invention provides a polynucleotide which encodes a CAR comprising a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VH and scFv VL to form a disulphide single chain variable fragment (dsscFv).

The present invention provides a polynucleotide which encodes a CAR comprising a first chain having the general format VH-spacer-transmembrane domain-signalling domain and a second chain having the general format VL-spacer-transmembrane domain-signalling domain wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

The present invention provides a polynucleotide which encodes a CAR comprising a transmembrane domain having the general format VH or VL-spacer-transmembrane domain signalling domain and a second domain comprising VL or VH, wherein the second domain is secreted and wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv). Nucleic acids encoding CARs according to the present invention may comprise DNA or RNA. They may be single-stranded or double-stranded. They may also be polynucleotides which include within them synthetic or modified nucleotides. A number of different types of modification to oligonucleotides are known in the art. These include methylphosphonate and phosphorothioate backbones, addition of acridine or polylysine chains at the 3' and/or 5' ends of the molecule. For the purposes of the use as described herein, it is to be understood that the polynucleotides may be modified by any method available in the art. Such modifications may be carried out in order to enhance the in vivo activity or life span of polynucleotides of interest. The polynucleotide may be in isolated or recombinant form. It may be incorporated into a vector and the vector may be incorporated into a host cell. Such vectors and suitable hosts form yet further aspects of the present invention.

The polynucleotide which encodes the CAR according to the present invention may be codon optimised. Different cells differ in their usage of particular codons. This codon bias corresponds to a bias in the relative abundance of particular tRNAs in the cell type. By altering the codons in the sequence so that they are tailored to match with the relative abundance of corresponding tRNAs, it is possible to increase expression. Suitably the polynucleotide may be codon optimised for expression in a murine model of disease. Suitably, the polynucleotide may be codon optimised for expression in a human subject.

Many viruses, including HIV and other lentiviruses, use a large number of rare codons and by changing these to correspond to commonly used mammalian codons, increased expression of the packaging components in mammalian producer cells can be achieved. Codon usage tables are known in the art for mammalian cells, as well as for a variety of other organisms.

Codon optimisation may also involve the removal of mRNA instability motifs and cryptic splice sites.

In one embodiment, the CAR may comprise a nucleic acid sequence which encodes a single chain variable fragment according to the present invention.

In one aspect, the CAR may comprise a nucleic acid sequence which encodes a CAR comprising a single chain variable fragment wherein one or more disulphide bonds are present between the VH domain and the VL domain to form a disulphide single chain variable fragment (dsscFv).

In another aspect, the CAR may comprise a nucleic acid sequence which encodes a first chain which encodes a VH domain. Suitably, the CAR may comprise a nucleic acid sequence which encodes a first chain with the general format: VH-spacer-transmembrane domain-signalling domain.

In one aspect, the CAR may comprise a nucleic acid sequence which encodes a second chain which encodes a VL domain. Suitably, the CAR may comprise a nucleic acid sequence which encodes a second chain with the general format: VL-spacer-transmembrane domain-signalling domain.

Suitably, the CAR may comprise a nucleic acid sequence which enables both a nucleic acid sequence encoding a first chain and a nucleic acid sequence encoding second chain to be expressed from the same mRNA transcript. Suitably, the CAR may comprise a nucleic acid encoding a first chain with the general format: VH-spacer-transmembrane domain-signalling domain and a second chain with the general format: VL-spacer-transmembrane domain signalling domain which are expressed from the same mRNA transcript.

For example, the CAR may comprise a polynucleotide which comprises an internal ribosome entry site (IRES) between the nucleic acid sequences which encode the VH chain and the VL chain. An IRES is a nucleotide sequence that allows for translation initiation in the middle of a mRNA sequence.

The CAR may comprise a nucleic acid sequence encoding a VH domain and a nucleic acid sequence a VL domain linked by an internal self-cleaving sequence.

The internal self-cleaving sequence may be any sequence which enables the polypeptide comprising the VH domain and the polypeptide comprising the VL domain to become separated.

The cleavage site may be self-cleaving, such that when the polypeptide is produced, it is immediately cleaved into individual peptides without the need for any external cleavage activity. The term “cleavage” is used herein for convenience, but the cleavage site may cause the peptides to separate into individual entities by a mechanism other than classical cleavage. For example, for the Foot-and-Mouth disease virus (FMDV) 2A self-cleaving peptide, various models have been proposed for to account for the“cleavage” activity: proteolysis by a host-cell proteinase, autoproteolysis or a translational effect (Donnelly et al (2001) J. Gen. Virol. 82:1027- 1041 incorporated herein by reference). The exact mechanism of such “cleavage” is not important for the purposes of the present invention, as long as the cleavage site, when positioned between nucleic acid sequences which encode proteins, causes the proteins to be expressed as separate entities.

The self-cleaving peptide may be a 2A self-cleaving peptide from an aphtho- or a cardiovirus. The present invention provides a nucleic acid construct which comprises a nucleic acid sequence which encodes a CAR according to the present invention.

The present invention provides a nucleic acid construct which comprises a nucleic acid sequence which encodes a CAR comprising a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VH and scFv VL to form a disulphide single chain variable fragment (dsscFv).

The present invention provides a nucleic acid construct which comprises a nucleic acid sequence which encodes a CAR comprising a first chain having the general format VH-spacer- transmembrane domain-signalling domain and a second chain having the general format VL- spacer-transmembrane domain-signalling domain wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

The present invention provides a nucleic acid construct which comprises a nucleic acid sequence which encodes a CAR comprising a transmembrane domain having the general format VH or VL-spacer-transmembrane domain-signalling domain and a second domain comprising VL or VH, wherein the second domain is secreted and wherein one or more inter chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv). VECTOR

The present invention also provides a vector comprising a nucleotide sequence encoding a CAR as described herein.

The present invention also provides a vector comprising a nucleic acid construct encoding a CAR as described herein.

Suitably, the vector may comprise a nucleotide sequence encoding a VH domain of the CAR of the present invention.

Suitably, the vector may comprise a nucleotide sequence encoding a VL domain of the CAR of the present invention.

Suitably, the vector may comprise a nucleotide sequence encoding a VH domain and a VL domain of the CAR of the present invention.

In one aspect, there is provided a kit of vectors which comprises one or more nucleic acid sequence(s) of the invention such as a nucleic acid encoding a VH domain and a nucleic acid encoding a VL domain of the CAR of the present invention.

The term "vector" as used herein includes an expression vector, i.e. , a construct enabling expression of a CAR according to the present invention i.e. a VH domain and/or VL domain according to the present invention.

Suitably the expression vector enables expression of a CAR according to the present invention. In some embodiments, the vector is a cloning vector.

Suitable vectors may include, but are not limited to, plasmids, viral vectors, transposons, nucleic acid complexed with polypeptide or immobilised onto a solid phase particle.

Viral delivery systems include but are not limited to adenovirus vector, an adeno-associated viral (AAV) vector, a herpes viral vector, retroviral vector, lentiviral vector, baculoviral vector. Retroviruses are RNA viruses with a life cycle different to that of lytic viruses. In this regard, a retrovirus is an infectious entity that replicates through a DNA intermediate. When a retrovirus infects a cell, its genome is converted to a DNA form by a reverse transcriptase enzyme. The DNA copy serves as a template for the production of new RNA genomes and virally encoded proteins necessary for the assembly of infectious viral particles.

There are many retroviruses, for example murine leukemia virus (MLV), human immunodeficiency virus (HIV), equine infectious anaemia virus (EIAV), mouse mammary tumour virus (MMTV), Rous sarcoma virus (RSV), Fujinami sarcoma virus (FuSV), Moloney murine leukemia virus (Mo-MLV), FBR murine osteosarcoma virus (FBR MSV), Moloney murine sarcoma virus (Mo-MSV), Abelson murine leukemia virus (A-MLV), Avian myelocytomatosis virus-29 (MC29), and Avian erythroblastosis virus (AEV) and all other retroviridiae including lentiviruses.

A detailed list of retroviruses may be found in Coffin et al (“Retroviruses” 1997 Cold Spring Harbour Laboratory Press Eds: JM Coffin, SM Hughes, HE Varmus pp 758-763) incorporated herein by reference. Lentiviruses also belong to the retrovirus family, but they can infect both dividing and non dividing cells (Lewis et al (1992) EMBO J. 3053-3058), incorporated herein by reference.

The vector may be capable of transferring a polynucleotide the invention to a cell, for example a host cell as defined herein. The vector should ideally be capable of sustained high-level expression in host cells, so that the VH and/or VL domain are suitably expressed in the host cell.

The vector may be a retroviral vector. The vector may be based on or derivable from the MP71 vector backbone. The vector may lack a full-length or truncated version of the Woodchuck Hepatitis Response Element (WPRE).

For efficient infection of human cells, viral particles may be packaged with amphotropic envelopes or gibbon ape leukemia virus envelopes.

CELL

The present invention further provides an engineered cell comprising a CAR according to the present invention. In one aspect, the engineered cell may comprise a polynucleotide or vector which encodes a CAR according to the present invention.

The engineered cell may be any cell which can be used to express and produce a CAR.

Suitably the cell may be an immune effector cell.

“Immune effector cell” as used herein is a cell which responds to a stimulus and effects a change i.e. the cell carries out a response to the stimulus. . Immune effector cells may include alpha/beta T cells, gamma/delta T cells, Natural killer (NK) cells and macrophages.

Suitably, the cell may be an alpha/beta T cell.

Suitably, the cell may be a gamma/delta T cell.

Suitably, the cell may be a T cell, such as a cytolytic T cell e.g. a CD8+ T cell.

Suitably, the cell may be an NK cell, such as a cytolytic NK cell.

Suitably, the cell may be a macrophage.

In one aspect, the cellmay be isolated from blood obtained from the subject. Suitably, the cell may be isolated from peripheral blood mononuclear cells (PBMCs) obtained from the subject.

In one aspect, the cell may be a stem cell.

In another aspect, the cell may be a progenitor cell.

As used herein, the term “stem cell” means an undifferentiated cell which is capable of indefinitely giving rise to more stem cells of the same type, and from which other, specialised cells may arise by differentiation. Stem cells are multipotent. Stem cells may be for example, embryonic stem cells or adult stem cells.

As used herein, the term“progenitor cell” means a cell which is able to differentiate to form one or more types of cells but has limited self-renewal in vitro.

Suitably, the cell may be capable of being differentiated into a T cell.

Suitably, the cell may be capable of being differentiated into an NK cell. Suitably, the cell may be capable of being differentiated into a macrophage.

Suitably, the cell may be an embryonic stem cell (ESC). Suitably, the cell is a haematopoietic stem cell or haematopoietic progenitor cell. Suitably, the cell is an induced pluripotent stem cell (iPSC). Suitably, the cell may be obtained from umbilical cord blood. Suitably, the cell may be obtained from adult peripheral blood.

In some aspects, hematopoietic stem and progenitor cell (HSPCs) may be obtained from umbilical cord blood. Cord blood can be harvested according to techniques known in the art (e.g., U.S. Pat. Nos. 7,147,626 and 7,131 ,958 which are incorporated herein by reference).

In one aspect, HSPCs may be obtained from pluripotent stem cell sources, e.g., induced pluripotent stem cells (iPSCs) and embryonic stem cells (ESCs).

As used herein, the term“hematopoietic stem and progenitor cell” or“HSPC” refers to a cell which expresses the antigenic marker CD34 (CD34+) and populations of such cells. In particular embodiments, the term “HSPC” refers to a cell identified by the presence of the antigenic marker CD34 (CD34+) and the absence of lineage (lin) markers. The population of cells comprising CD34+ and/or Lin(-) cells includes haematopoietic stem cells and hematopoietic progenitor cells.

HSPCs can be obtained or isolated from bone marrow of adults, which includes femurs, hip, ribs, sternum, and other bones. Bone marrow aspirates containing HSPCs can be obtained or isolated directly from the hip using a needle and syringe. Other sources of HSPCs include umbilical cord blood, placental blood, mobilized peripheral blood, Wharton's jelly, placenta, fetal blood, fetal liver, or fetal spleen. In particular embodiments, harvesting a sufficient quantity of HSPCs for use in therapeutic applications may require mobilizing the stem and progenitor cells in the subject.

As used herein, the term“induced pluripotent stem cell” or“iPSC” refers to a non-pluripotent cell that has been reprogrammed to a pluripotent state. Once the cells of a subject have been reprogrammed to a pluripotent state, the cells can then be programmed to a desired cell type, such as a hematopoietic stem or progenitor cell (HSC and HPC respectively).

As used herein, the term“reprogramming” refers to a method of increasing the potency of a cell to a less differentiated state.

As used herein, the term“programming” refers to a method of decreasing the potency of a cell or differentiating the cell to a more differentiated state.

Suitably the cell is matched or is autologous to the subject. The cell may be generated ex vivo either from a patient’s own peripheral blood (1st party), or in the setting of a haematopoietic stem cell transplant from donor peripheral blood (2nd party), or peripheral blood from an unconnected donor (3rd party).

Suitably the cell may be autologous to the subject.

In some aspects, the cell may be derived from ex-vivo differentiation of inducible progenitor cells or embryonic progenitor cells to the immune cell. In these instances, cells are generated by introducing DNA or RNA coding for the CAR of the present invention by one of any means including transduction with a viral vector, transfection with DNA or RNA.

Basal activation

An advantage of CAR therapy over other immunotherapies known in the art, such as monoclonal antibodies or bi-specific T-cell engagers, is that CAR-engineered cells have the potential to engraft, home to sites, proliferate and persist. These functions depend on the ability of the T-cell to survive without antigen stimulation and to have the ability to perform serial killing without terminally differentiation or succumbing to activation induced cell death.

Basal activation (also known as tonic signalling) of a CAR-engineered cell may cause several problems. For example, basal activation may lead to chronically exhausted cells (e.g. chronically exhausted T cells) which cannot persist in vivo. It has been demonstrated by Grupp, S. A. et al. Blood 126, 681-681 (2015) (incorporated herein by reference) that in certain disease settings, such as B cell acute lymphoblastic leukaemia (B-ALL), persistence of CAR T-cells is linked with sustained remissions. Thus, engineered CAR T-cells which are capable of persisting in vivo are desirable for effective therapies.

Without wishing to be bound by theory, basal activation may also cause non-specific activity against target calls and/or increase immune toxicity. Reducing basal activity of CARs may be beneficial in generating more effective CAR-engineered cell therapies with improved cellular migration and/or improved in vivo expansion and/or improved in vivo persistence and/or enhanced safety.

As used herein“basal signalling” or tonic signalling refers to antigen-independent signalling. Basal signalling by CARs can increase differentiation and exhaustion of cells.

T cell exhaustion induced by basal signalling is described in Long, A. H. et al. Nat. Med. 21 , 581-590 (2015), which is incorporated herein by reference.

In one aspect the present invention provides CARs with decreased basal signalling. Suitably an engineered cell comprising the CAR according to the present invention has decreased basal signalling compared with an engineered cell comprising a CAR which does not comprise a disulphide bond according of the present invention.

Methods for measuring basal signalling are known in the art. For example, phosphorylation of proximal TCR signalling components such as the

chain immunoreceptor tyrosine-based activation motifs (ITAM), and constitutive Zap70 association with phosphor-TC^ may be measured as an indication of basal signalling activity. Phosphorylation events may be measured by any method known in the art such as western blot or capillary electrophoresis. The level of basal signalling may also be inferred from the cytolytic activity, proliferation activity and effector cytokine production of an engineered CAR cell particularly in the absence of target antigen. Differentiation

In one aspect, the engineered cells according to the present invention or obtainable (e.g. obtained) by a method according to the present invention are less differentiated than engineered cells which do not comprise a CAR according to the present invention i.e. do not comprise a disulphide bond as described herein.

Studies in mouse models suggest that improved anti-tumour responses are achieved when engineered T cells are in the early stages of differentiation.

As used herein“differentiated” refers to the stage of development of a particular cell within the linear progression of differentiation of that cell type. For example, CD8+ T cells can be categorised into distinct memory subsets based on their differentiation states. The differentiation state of a cell is inversely related to its capacity to proliferate and persist.

As used herein,“naive” means a cell which is not fully differentiated. A naive cell may not have encountered antigen.

Naive T cells may be characterised by the surface expression of L selection (CD62L), the absence of activation markers CD25, CD44 or CD69 and the absence of memory CD45RO isoform e.g. naive T cells may be CD62L^HICD25^LOCD44^LOCD69^Lo. Naive T cells may also express functional IL-7 receptors, consisting of subunits IL-7 receptor-a, CD127, and common-y chain, CD132.

Suitably, the engineered cells according to the invention may have a naive phenotype.

A naive engineered cell population may be advantageous for use methods of treatment because naive cells may exhibit enhanced persistence in vivo and enhanced cytolytic activity when compared to cells with a more differentiated phenotype.

T cells which are considered to have the capability to engraft include naive T cells, central memory T cells and stem-cell memory T cells.

“Central memory T cells” (T_CM) are T cells which are commonly found in the lymph nodes and peripheral circulation and mount recall responses to antigen. These cells rapidly proliferate and differentiate into effector T cells following antigen stimulation. Central memory T cells may be for example, CD45RO⁺, CCR7^hi, CD44⁺, CD62L^hi, TCR⁺, CD3⁺, IL-7R⁺ (CD127⁺), IL-15R+ and express high levels of CD62L and CCR7.

“Stem-cell memory T cells” (TSCM) are T cells which have the ability to self-renew and the multipotent capacity to reconstitute the entire spectrum of memory and effector T cell subsets. TSCM cells may be for example, CD45RO , CCR7⁺, CD45RA⁺, CD62L⁺, CD27⁺, CD28⁺ and IL- 7Ra⁺ and express increased levels of CD95, IL-2Rb, CXCR3, and LFA-1.

Suitably, the engineered cells according to the invention may be naive T cells.

Suitably, the engineered cells according to the invention may be central memory T cells.

Suitably, the engineered cells according to the invention may be stem-cell memory T cells (TSCM). Differentiation markers may be measured by any method known in the art for example, by immunophenotyping e.g. by FACS or by immunohistochemistry.

Exhaustion

In one aspect the present invention provides engineered cells which are less exhausted than cells engineered with a CAR which does not comprise a CAR according to the present invention.

As used herein“exhaustion” or“exhausted” means that the cell exhibits decreased effector functions and/or altered phenotype. Immune cell exhaustion describes the status of dysfunction of immune cells, usually under the setting of tumours or chronic infection. Exhaustion may be accompanied by phenotypic changes, epigenetic modifications and alterations in transcriptional profiles.

Effector functions may include the production of effector cytokines and direct cytotoxic activity. Suitably the engineered cells according to the present invention or obtainable (or obtained) by a method according to the present invention may have decreased expression of one or more exhaustion markers compared with engineered cells which were not prepared according to a method of the present invention i.e. do not comprise a CAR according to the present invention.

In the context of an engineered T cells, exhaustion may be defined by poor effector function, sustained expression of inhibitory receptors and/or a transcriptional state distinct from that of functional effector or memory T cells.

For example, exhausted T cells may express high levels of: PD1 , Tim3, Lag3, CD43 (1 B11), CD69 and inhibitory receptors but low levels of: CD62L and CD127 and decreased production of: interleukin-2 (IL-2), TNF-a and IFN-y.

Suitably, the one or more exhaustion markers may comprise increased (e.g. high) expression of PD1.

Suitably, the one or more exhaustion markers may comprise increased (e.g. high) expression of Tim3.

Suitably, the one or more exhaustion markers may comprise increased (e.g. high) expression of Lag 3.

Suitably, the one or more exhaustion markers may comprise increased (e.g. high) expression of CD43 (1 B11). Suitably, the one or more exhaustion markers may comprise increased (e.g. high) expression of CD69.

Suitably, the one or more exhaustion markers may comprise increased (e.g. high) expression of inhibitory receptors. Suitably, the one or more exhaustion markers may comprise decreased (e.g. low) expression of CD62L.

Suitably, the one or more exhaustion markers may comprise decreased (e.g. low) expression of CD127. Suitably, the one or more exhaustion markers may comprise decreased (e.g. low) IL-2 production.

Suitably, the one or more exhaustion markers may comprise decreased (e.g. low) TNF-a production.

Suitably, the one or more exhaustion markers may comprise decreased (e.g. low) IFN-y production.

Suitably comparisons such as high, low, increased, decreased, may be made between engineered cells comprising the CAR according to the present invention and engineered cells which comprise a corresponding CAR which does not comprise a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VH and scFv VL to form a disulphide single chain variable fragment (dsscFv). A corresponding CAR as used herein means a CAR which is identical to the CAR of the present invention except for the absence of a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VH and scFv VL to form a disulphide single chain variable fragment (dsscFv). Suitably the comparison will be made with between CARs which differ only in the presence of comprising a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VH and scFv VL to form a disulphide single chain variable fragment (dsscFv).

Suitably comparisons such as high, low, increased, decreased, may be made between engineered cells comprising the CAR according to the present invention and engineered cells which comprise a corresponding CAR which does not comprise a first chain having the general format VH-spacer-transmembrane domain-signalling domain and a second chain having the general format VL-spacer-transmembrane domain-signalling domain wherein one or more inter chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv). A corresponding CAR as used herein means a CAR which is identical to the CAR of the present invention except for the absence of a first chain having the general format VH-spacer-transmembrane domain-signalling domain and a second chain having the general format VL-spacer-transmembrane domain-signalling domain wherein one or more inter chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv). Suitably the comparison will be made with between CARs which differ only in the presence of a first chain having the general format VH-spacer-transmembrane domain-signalling domain and a second chain having the general format VL-spacer- transmembrane domain-signalling domain wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

The one or more exhaustion markers may be selected from those recited above. Suitably, one or more exhaustion markers may be two exhaustion markers. Suitably, one or more exhaustion markers may be three exhaustion markers. Suitably, one or more exhaustion markers may be four exhaustion markers. Suitably, one or more exhaustion markers may be five exhaustion markers. Suitably, one or more exhaustion markers may be six exhaustion markers. Suitably, one or more exhaustion markers may be seven exhaustion markers.

Methods for measuring exhaustion are known in the art. For example, the expression of exhaustion markers may be measured using antibodies by fluorescence-activated cell sorting, western blot, or by qPCR. Methods for measuring cytokine production may include intracellular staining of IFNy and/or TNFa and/or IL-2 followed by FACS. Alternatively, the presence of said cytokines in the culture media of engineered cells may be measured e.g. by enzyme-linked immunosorbent assay (ELISA).

Degranulation

Cytotoxic CD8+ T cells mediate the killing of target cells via two main pathways: (1) perforin- granzyme-mediated activation of apoptosis and (2) fas-fas ligand-mediated induction of apoptosis. Induction of these pathways depends on the release of cytolytic granules from the responding CD8+ T cells.

In one aspect, the engineered cells according to the present invention exhibit increased levels of degranulation compared with engineered cells which do not comprise a CAR according to the present invention.

“Degranulation” as used herein refers to the release of pre-formed lytic granules from the cytoplasm of a cytolytic cell e.g. T cell. The granules may be released in a polarised manner towards the target cell.

Degranulation may be measured by any method known in the art, for example by measuring expression of one or more degranulation markers, e.g. CD107, on the surface of a cell. Degranulation may be measured using antibodies to the degranulation marker, e.g. antibodies to CD107a and/or CD107b, and measuring their expression by flow cytometry.

In one aspect, the engineered cells of the present invention, or obtainable (e.g. obtained) by a method according to the invention may comprise higher levels of a degranulation marker (suitably CD107a) on the cell surface when compared with a CAR engineered cell which does not comprise a CAR comprising a disulphide bond according to the present invention.

In one aspect, the engineered cells of the present invention, or obtainable (e.g. obtained) by a method according to the invention may comprise higher levels of a degranulation marker (suitably CD107b) on the cell surface when compared with a CAR engineered cell which does not comprise a CAR comprising a disulphide bond according to the present invention. In one aspect, the engineered cells of the present invention, or obtainable (e.g. obtained) by a method according to the invention may comprise higher levels of CD107a and CD107 b on the cell surface when compared with a CAR engineered cell which does not comprise a CAR comprising a disulphide bond according to the present invention.

Suitably comparisons such as high, low, higher, lower, increased, decreased, may be made between engineered cells comprising the CAR according to the present invention and engineered cells which comprise a corresponding CAR which does not comprise a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VH and scFv VL to form a disulphide single chain variable fragment (dsscFv). A corresponding CAR as used herein means a CAR which is identical to the CAR of the present invention except for the absence of a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VH and scFv VL to form a disulphide single chain variable fragment (dsscFv). Suitably the comparison will be made with between CARs which differ only in the presence of comprising a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VH and scFv VL to form a disulphide single chain variable fragment (dsscFv).

Suitably comparisons such as high, low, higher, lower, increased, decreased, may be made between engineered cells comprising the CAR according to the present invention and engineered cells which comprise a corresponding CAR which does not comprise a first chain having the general format VH-spacer-transmembrane domain-signalling domain and a second chain having the general format VL-spacer-transmembrane domain-signalling domain wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv). A corresponding CAR as used herein means a CAR which is identical to the CAR of the present invention except for the absence of a first chain having the general format VH-spacer-transmembrane domain-signalling domain and a second chain having the general format VL-spacer-transmembrane domain-signalling domain wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv). Suitably the comparison will be made with between CARs which differ only in the presence of a first chain having the general format VH- spacer-transmembrane domain-signalling domain and a second chain having the general format VL-spacer-transmembrane domain-signalling domain wherein one or more inter-chain disulphide bonds are present between the VH and VL to form a disulphide stabilised variable fragment (dsFv).

COMPOSITIONS

The present invention also provides a composition comprising an engineered cell according to the invention. Suitably, the composition may comprise a population of cells according to the present invention.

Suitably the present invention provides a composition comprising an engineered T cell according to the present invention. Suitably the composition may comprise a population of engineered T cells according to the present invention.

In some embodiments, the composition is a pharmaceutical composition. Such pharmaceutical composition may comprise a pharmaceutically acceptable carrier, diluent, excipient or adjuvant. The choice of pharmaceutical carrier, excipient or diluent can be selected with regard to the intended route of administration and standard pharmaceutical practice. The pharmaceutical compositions may comprise as (or in addition to) the carrier, excipient or diluent, any suitable binder(s), lubricant(s), suspending agent(s), coating agent(s), solubilising agent(s) and other carrier agents.

The pharmaceutical compositions typically should be sterile and stable under the conditions of manufacture and storage. Formulations for parenteral administration include, but are not limited to, suspensions, solutions, emulsions in oily or aqueous vehicles, pastes, and implantable sustained-release or biodegradable formulations as discussed herein. Sterile injectable formulations may be prepared using a non-toxic parenterally acceptable diluent or solvent. A pharmaceutical composition for use in accordance with the present invention may include pharmaceutically acceptable dispersing agents, wetting agents, suspending agents, isotonic agents, coatings, antibacterial and antifungal agents, carriers, excipients, salts, or stabilizers which are non-toxic to the subjects at the dosages and concentrations employed. Preferably, such a composition can further comprise a pharmaceutically acceptable carrier or excipient for use in the treatment of disease that that is compatible with a given method and/or site of administration, for instance for parenteral (e.g. sub-cutaneous, intradermal, or intravenous injection) or intrathecal administration.

Wherein the pharmaceutical composition comprises a cell according to the invention, the composition may be produced using current good manufacturing practices (cGMP).

Suitably the pharmaceutical composition comprising a cell according to the present invention may comprise an organic solvent, such as but not limited to, methyl acetate, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), dimethoxyethane (DME), and dimethylacetamide, including mixtures or combinations thereof.

Suitably the pharmaceutical composition comprising a cell according to the present invention is endotoxin free.

METHOD OF TREATMENT/USES

The present invention provides a method for treating and/or preventing a disease which comprises the step of administering an engineered cell of the present invention or obtainable (e.g. obtained) by a method according to the present invention to a subject.

The present invention provides a method for treating and/or preventing a disease which comprises the step of administering a pharmaceutical composition of the present invention or obtainable (e.g. obtained) by a method according to the present invention to a subject.

The present invention also provides an engineered cell of the present invention or obtainable (e.g. obtained) by a method according to the present invention for use in treating and/or preventing a disease.

The present invention also provides a pharmaceutical composition of the present invention for use in treating and/or preventing a disease. The invention also relates to the use of an engineered cell according to the present invention in the manufacture of a medicament for treating and/or preventing a disease.

Preferably, the present methods of treatment relate to the administration of a pharmaceutical composition of the present invention to a subject.

The term“treat/treatment/treating” refers to administering an engineered cell or pharmaceutical composition as described herein to a subject having an existing disease or condition in order to lessen, reduce or improve at least one symptom associated with the disease and/or to slow down, reduce or block the progression of the disease.

Reference to“preventionTpreventing” (or prophylaxis) as used herein refers to delaying or preventing the onset of the symptoms of the disease. Prevention may be absolute (such that no disease occurs) or may be effective only in some individuals or for a limited amount of time.

In a preferred embodiment of the present invention, the subject of any of the methods described herein is a mammal, preferably a cat, dog, horse, donkey, sheep, pig, goat, cow, mouse, rat, rabbit or guinea pig. Preferably the subject is a human.

The administration of a pharmaceutical composition of the invention can be accomplished using any of a variety of routes that make the active ingredient bioavailable. For example, a cell or pharmaceutical composition according to the invention may be administered intravenously, intrathecally, by oral and parenteral routes, intranasally, intraperitoneally, subcutaneously, transcutaneously or intramuscularly.

Suitably, the engineered cell according to the present invention or the pharmaceutical composition according to the invention may be administered intravenously.

Suitably, the engineered cell according to the present invention or the pharmaceutical composition according to the present invention is administered intrathecally.

Typically, a physician will determine the actual dosage that is most suitable for an individual subject and it will vary with the age, weight and response of the particular patient. The dosage is such that it is sufficient to reduce and/or prevent disease symptoms.

Those skilled in the art will appreciate, for example, that route of delivery (e.g., oral vs intravenous vs subcutaneous, etc.) may impact dose amount and/or required dose amount may impact route of delivery. For example, where particularly high concentrations of an agent within a particular site or location are of interest, focused delivery may be desired and/or useful. Other factors to be considered when optimizing routes and/or dosing schedule for a given therapeutic regimen may include, for example, the disease being treated (e.g., type or stage, etc.), the clinical condition of a subject (e.g., age, overall health, etc.), the presence or absence of combination therapy, and other factors known to medical practitioners.

The dosage is such that it is sufficient to stabilise or improve symptoms of the disease.

The present invention also provides a method for treating and/or preventing a disease, which comprises the step of administering a pharmaceutical composition comprising an engineered cell e.g. a cell which has been engineered to express a CAR according to the present invention to a subject.

Suitably, the present invention also provides a method for treating and/or preventing a disease, which comprises the step of administering an engineered cell according to the invention or obtainable (e.g. obtained) by a method according to the present invention to a subject.

The method may comprise the following steps:

(i) isolation of a cell-containing sample from a subject;

(ii) introducing a nucleic acid sequence encoding a CAR according to the present invention; and

(iii) administering the cells from (ii) to the subject.

Suitably, the cells from (ii) may be expanded in vitro before administration to the subject.

DISEASE

The disease may be, for example, a cancer, infectious disease or autoimmune disease.

Suitably the disease to be treated and/or prevented by the methods and uses of the present invention may be an autoimmune disease.

Suitably, the disease to be treated and/or prevented by the methods and uses of the present invention may be a cancer.

Suitably, the disease to be treated and/or prevented by the methods and uses of the present invention may be a haematological malignancy.

As used herein,“haematological malignancy” refers to a cancer which affects the blood and lymph system and includes leukaemia, lymphoma, myeloma and related blood disorders.

Suitably, the disease to be treated and/or prevented by the methods and uses of the present invention may be an infectious disease.

Suitably, the disease to be treated and/or prevented by the methods and uses of the present invention may be an autoimmune disease.

METHOD

The present invention also provides a method for producing an engineered cell, which method comprises introducing into a cell in vitro or ex vivo, a polynucleotide encoding a CAR as defined herein. Suitably, the method may comprise introducing into a cell in vitro or ex vivo, a nucleic acid construct encoding a CAR as defined herein. Suitably, the method may comprise introducing into a cell in vitro or ex vivo, a vector which comprises a polynucleotide encoding a CAR as defined herein. Suitably, the method may further comprise incubating the cell under conditions permitting expression of the CAR molecule of the present invention. Optionally, the method may further comprise a step of purifying the engineered cells.

Suitably, the cell is a cytolytic cell.

Suitably, the cell is a T cell. Suitably, the cell is an NK cell.

In one aspect, the cell is a stem cell. Suitably, in the method according to the invention, a nucleic acid encoding a CAR as defined herein has been introduced into the stem cell and the stem cell is then differentiated into a T cell. Suitably, in the method according to the invention, a nucleic acid encoding a CAR as defined herein has been introduced into the stem cell and the stem cell is then differentiated into an NK cell.

Suitably, the stem cell has the ability to differentiate into a T cell.

Suitably, the stem cell has the ability to differentiate into an NK cell.

Suitably, the cell may be an embryonic stem cell (ESC). Suitably, the cell may be obtained from umbilical cord blood. Suitably, the cell may be obtained from adult peripheral blood. Suitably, the cell is a haematopoietic stem and progenitor cell (HSPC). Suitably, the cell is an induced pluripotent stem cell (iPSC).

In another aspect, the cell is a progenitor cell. Suitably the progenitor cell has the ability to differentiate into a T cell. Suitably, the progenitor cell has the ability to differentiate into an NK cell.

In another aspect, the invention provides a method for producing an engineered cell comprising a CAR wherein the CAR comprises two chains. Suitably a first chain comprises a VH domain and a second chain comprises a VL domain.

Suitably, the method may comprise introducing into a cell in vitro or ex vivo a polynucleotide encoding a CAR chain comprising a VH domain and a polynucleotide encoding a CAR chain comprising a VL domain.

Suitably, the CAR VH domain and the CAR VL domain may be provided by the same polynucleotide.

Suitably the CAR VH domain and the CAR VL domain may be provided as separate polynucleotides.

Suitably, the separate polypeptides may be introduced separately, sequentially or simultaneously into the cell. Wherein the polypeptides are introduced separately or sequentially, suitably the polynucleotide encoding the VH domain may be introduced first. Wherein the polypeptides are introduced separately or sequentially, suitably the polynucleotide encoding the VL domain may be introduced first.

Suitably, the method further may comprise incubating the cell under conditions causing expression the CAR molecule of the present invention. Optionally, the method may further comprise a step of purifying the engineered cells.

In one aspect, the invention provides a method for producing an engineered cell, which method comprises introducing into a cell in vitro or ex vivo a polynucleotide encoding a VH domain and a polynucleotide encoding a VL domain and differentiating the cell into a T cell. Suitably, the method may further comprise incubating the cell under conditions causing expression of the CAR molecule of the present invention. Optionally, the method may further comprise a step of purifying the engineered cells comprising the CAR according to the invention.

Suitably, in one aspect the cell may be differentiated into a T cell before the one or more polynucleotide(s) encoding the CAR are introduced into the cell.

Purification of the engineered cell may be achieved by any method known in the art. Suitably, the engineered cell may be purified using fluorescence-activated cell sorting (FACS) or immunomagnetic isolation (i.e. using antibodies attached to magnetic nanoparticles or beads) using positive and/or negative selection of cell populations.

Suitably, purification of the engineered cell may be performed using the expression of the CAR as defined herein.

The present invention also provides a method for enhancing the stability of a CAR, which method comprises introducing a cysteine residue into the VH domain and a cysteine residue into the VL domain of said CAR.

The stability of the CAR may be enhanced or increased relative to a corresponding CAR which does not comprise said cysteine residues. Methods for measuring the stability of CARs are known in the art and may include, for example, measuring the cell surface expression of the CAR by flow cytometry.

Suitably, a disulphide bond may be formed between the cysteine residue in the VH domain and the cysteine residue in the VL domain.

Suitably the CAR may comprise a disulphide stabilised variable fragment (dsFv).

Suitably, the CAR may comprise a disulphide single chain variable fragment (dsscFv).

Suitable positions in the VH and VL for introducing cysteine residues may be determined using methods known in the art. For example, suitable positions may be identified by using the predicted or actual structure of the antigen binding domain of the CAR.

USE

The present invention also provides a pharmaceutical composition or engineered cell (e.g. a population of engineered cells) according to the invention or obtainable (e.g. obtained) by a method according to the present invention for use in treating disease. The pharmaceutical composition or engineered cell(s) may be any as defined above.

The present invention also relates to the use of an engineered cell or population of engineered cells according to the present invention or obtainable (e.g. obtained) by a method according to the present invention as defined above in the manufacture of a medicament for the treatment of a disease.

This disclosure is not limited by the exemplary methods and materials disclosed herein, and any methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of this disclosure. Numeric ranges are inclusive of the numbers defining the range. Unless otherwise indicated, any nucleic acid sequences are written left to right in 5' to 3' orientation; amino acid sequences are written left to right in amino to carboxy orientation, respectively.

Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within this disclosure. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within this disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in this disclosure.

It must be noted that as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise.

The terms "comprising", "comprises" and "comprised of as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. The terms "comprising", "comprises" and "comprised of also include the term "consisting of.

It is noted that embodiments of the invention as described herein may be combined.

The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that such publications constitute prior art to the claims appended hereto.

The invention will now be further described by way of Examples, which are meant to serve to assist one of ordinary skill in the art in carrying out the invention and are not intended in any way to limit the scope of the invention.

EXAMPLES

Example 1 - Production of Chimeric antigen receptors (CARs)

CARs are constructed from a number of scFv which recognize tumour antigens. CARs identical to these original CARs but with the addition of disulphide bond stabilized cysteines are generated.

The CARs are constructed in the Campana format (Imai, C. et al. Leuk. Off. J. Leuk. Soc. Am. Leuk. Res. Fund UK 18, 676-684 (2004), incorporated herein by reference), with the scFv as VH-VL with a CD8 spacer and transmembrane domain and a 41 BB-Zeta endodomain.

Example 2 - Demonstration of CAR-T cell functionality

Primary human T-cells are transduced with retroviral vectors encoding the CARs of Example 1. Functional assays are performed as follows: The stability of the CARs is tested e.g. by staining with soluble cognate antigen.

The basal activity of the CAR T-cells is determined e.g. by flow- cytometric analysis which identifies markers of exhaustion and degranulation.

Basal activity is also assessed by measuring cytokines in culture in the absence of target cells.

Example 3 - Demonstration of cytolytic activity of CAR-T cells

CAR T-cells of the present invention produced in Example 2 are co-cultured with target cells which express the target antigen or which do not expressing the target antigen.

Killing of the target cells is determined by flow-cytometry. Non-specific killing by the CAR T-cells is determined by measuring killing of target cells not expressing the cognate antigen as well as cytokine release in response to these target cells.

Differentiation and exhaustion of the CAR T-cells after antigen exposure is determined e.g. by flow-cytometric analysis of differentiation markers and exhaustion markers.

All publications mentioned in the above specification are herein incorporated by reference. Various modifications and variations of the described methods and system of the invention will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in molecular biology, cellular immunology or related fields are intended to be within the scope of the following claims.

FUNDING

One of the inventors of the present invention received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n°602239.

Claims

1. A chimeric antigen receptor (CAR) comprising a single chain variable fragment (scFv) wherein one or more disulphide bonds are present between scFv VFI and scFv VL to form a disulphide single chain variable fragment (dsscFv).

2. A chimeric antigen receptor (CAR) according to claim 1 wherein the CAR comprises the general format dsscFv-spacer-transmembrane domain-signalling domain.

3. A chimeric antigen receptor (CAR) comprising a first chain having the general format VFI-spacer-transmembrane domain-signalling domain and a second chain having the general format VL-spacer-transmembrane domain-signalling domain wherein one or more inter-chain disulphide bonds are present between the VFI and VL to form a disulphide stabilised variable fragment (dsFv).

4. A chimeric antigen receptor (CAR) comprising a first chain having the general format VFI or VL-spacer-transmembrane domain-signalling domain and a second chain comprising a VL or VFI, wherein the second chain is secreted and wherein one or more inter-chain disulphide bonds are present between the VFI and VL to form a disulphide stabilised variable fragment (dsFv).

5. A chimeric antigen receptor (CAR) according to claim 1 , claim 3, or claim 4 wherein the CAR comprises the general format dsscFv-CD3 or TCR element-transmembrane domain-signalling domain.

6. A chimeric antigen receptor (CAR) according to any preceding claim wherein the CAR is a multi-span protein.

7. A chimeric antigen receptor (CAR) according to any preceding claim wherein said CAR comprises a split receptor such that the antigen recognition domain is a separate protein from the signalling domain.

8. A chimeric antigen receptor (CAR) according to any one of the preceding claims

wherein the one or more disulphide bonds are between framework regions.

9. A chimeric antigen receptor (CAR) according to any one of the preceding claims

wherein the one or more disulphide bonds are between complementarity determining regions (CDRs).

10. A chimeric antigen receptor (CAR) according to any one of the preceding claims wherein the one or more disulphide bonds are between positions 44 VH FR2 and position 100 in VL FR4.

1 1. A chimeric antigen receptor (CAR) according to any one of the preceding claims wherein the one or more disulphide bonds are between positions 105 VFI FR4 and position 43 in VL FR2.

12. A polynucleotide which encodes a CAR according to any preceding claim.

13. A nucleic acid construct which comprises a first nucleic acid sequence which encodes a first chain of a CAR according to claim 3 or 4, and a second nucleic acid sequence which encodes a second chain of a CAR according to claim 3 or 4.

14. A vector which comprises a polynucleotide according to claim 12 or a nucleic acid construct according to claim 13.

15. An engineered cell comprising said chimeric antigen receptor (CAR) according to any one of the preceding claims.

16. A pharmaceutical composition which comprises a cell according to claim 15.

17. A pharmaceutical composition according to claim 16 for use in treating and/or

preventing a disease.

18. A method for treating and/or preventing a disease, which comprises the step of

administering a pharmaceutical composition according to claim 16 to a subject in need thereof.

19. Use of a pharmaceutical composition according to claim 16 in the manufacture of a medicament for the treatment and/or prevention of a disease.

20. A method for making a cell according to claim 15 which comprises transducing or transfecting a cell with a polynucleotide according to claim 12, or a nucleic acid construct according to claim 13, or vector according to claim 14.

21 . A method for enhancing the stability of a CAR by introducing a cysteine residue into the VH domain and a cysteine residue into the VL domain.

22. A method according to claim 21 , wherein a cysteine residue is introduced into position 44 or 105 of the VH domain and into position 43 or 100 of the VL domain.