Cell

1. A T cell or natural killer (NK) cell which co-expresses a first chimeric antigen receptor (CAR) and second CAR at the cell surface, each CAR comprising:

(i) an antigen-binding domain;

(ii) a spacer

(iii) a trans-membrane domain; and

(iv) an endodomain,

wherein the antigen binding domains of the first and second CARs bind to different antigens;

wherein one of the first or second CARs is an activating CAR comprising an Immunoreceptor Tyrosine-based Activation motif (ITAM)-containing activating endodomain and the other CAR is an inhibitory CAR comprising a ligation-on inhibitory endodomain comprising a tyrosine phosphatase domain from a Src homolog (SH2) domain-containing protein tyrosine phosphatase which is recruited by a phosphorylated Immunoreceptor Tyrosine-based Activation motif (ITIM); and wherein the spacer of the first CAR and the spacer of the second CAR co-localise upon ligation of the first CAR and the second CAR.

2. The T or NK cell according to claim 1 , wherein one of the first or second CARs in an activating CAR comprising an activating endodomain, and the other CAR is an inhibitory CAR comprising a ligation-on inhibitory endodomain, which inhibitory CAR does not significantly inhibit T-cell activation by the activating CAR in the absence of inhibitory CAR ligation, but inhibits T-cell activation by the activating CAR when the inhibitory CAR is ligated.

3. The T or NK cell according to claim 1 or 2 , wherein the ligation-on inhibitory endodomain comprises all or part of PTPN6.

4. A nucleic acid sequence encoding a first chimeric receptor (CAR) and second CAR, each CAR comprising:

(i) an antigen-binding domain,

(ii) a spacer,

(iii) a trans-membrane domain and

(iv) an endomain,

wherein the antigen binding domains of the first and the second CARs bind to different antigens, and

wherein one of the first or second CARs is an activating CAR comprising an Immunoreceptor Tyrosine-based Activation motif (ITAM)-containing activating endodomain and the other CAR is an inhibitory CAR comprising a ligation-on inhibitory endodomain comprising a tyrosine phosphatase domain from a Src homolog (SH2) domain-containing protein tyrosine phosphatase which is recruited by a phosphorylated Immunoreceptor Tyrosine-based Activation motif (ITIM); and wherein the spacer of the first CAR and the spacer of the second CAR co-localise upon ligation of the first CAR and the second CAR.

5. A nucleic acid sequence according to claim 4 , which has the following structure:

AgB1-spacer1-TM1-endo1-coexpr-AbB2-spacer2-TM2-endo2

in which

AgB1 is a nucleic acid sequence encoding the antigen-binding domain of the first CAR;

spacer 1 is a nucleic acid sequence encoding the spacer of the first CAR;

TM1 is a nucleic acid sequence encoding the transmembrane domain of the first CAR;

endo 1 is a nucleic acid sequence encoding the endodomain of the first CAR;

coexpr is a nucleic acid sequence enabling co-expression of both CARs

AgB2 is a nucleic acid sequence encoding the antigen-binding domain of the second CAR;

spacer 2 is a nucleic acid sequence encoding the spacer of the second CAR;

TM2 is a nucleic acid sequence encoding the transmembrane domain of the second CAR;

endo 2 is a nucleic acid sequence encoding the endodomain of the second CAR;

which nucleic acid sequence, when expressed in a T cell, encodes a polypeptide which is cleaved at the cleavage site such that the first and second CARs are co-expressed at the T cell surface.

6. The nucleic acid sequence according to claim 5 , wherein coexpr encodes a sequence comprising a self-cleaving peptide.

7. The nucleic acid sequence according to claim 5 , wherein alternative codons are used in regions of sequence encoding the same or similar amino acid sequences, in order to avoid homologous recombination.

8. A kit which comprises

a first nucleic acid sequence encoding a first chimeric antigen receptor (CAR) and a second nucleic acid encoding a second CAR, each CAR comprising

(i) an antigen-binding domain,

(ii) a spacer,

(iii) a trans-membrane domain and

(iv) an endodomain,

wherein the antigen binding domains of the first and second CARs bind to different antigens,

wherein one of the first or second CARs is an activating CAR comprising an Immunoreceptor Tyrosine-based Activation motif (ITAM)-containing activating endodomain and the other CAR is an inhibitory CAR comprising a ligation-on inhibitory endodomain comprising a tyrosine phosphatase domain from a Src homolog (SH2) domain-containing protein tyrosine phosphatase which is recruited by a phosphorylated Immunoreceptor Tyrosine-based Activation motif (ITIM); and wherein the spacer of the first CAR and the spacer of the second CAR co-localise upon ligation of the first CAR and the second CAR,

wherein the first nucleic acid sequence has the following structure:

AgB1-spacer1-TM1-endo1

in which AgB1 is a nucleic acid sequence encoding the antigen-binding domain of the first CAR; spacer 1 is a nucleic acid sequence encoding the spacer of the first CAR;

TM1 is a nucleic acid sequence encoding the transmembrane domain of the first CAR; endo 1 is a nucleic acid sequence encoding the endodomain of the first CAR; and

wherein the second nucleic acid sequence encoding the second CAR has the following structure:

AgB2-spacer2-TM2-endo2

in which AgB2 is a nucleic acid sequence encoding the antigen-binding domain of the second CAR; spacer 2 is a nucleic acid sequence encoding the spacer of the second CAR; TM2 is a a nucleic acid sequence encoding the transmembrane domain of the second CAR; endo 2 is a nucleic acid sequence encoding the endodomain of the second CAR.

9. A kit comprising: a first vector which comprises the first nucleic acid sequence as defined in claim 8 ; and a second vector which comprises the second nucleic acid sequence as defined in claim 8 .

10. A vector comprising a nucleic acid sequence according to claim 4 .

11. The vector according to claim 10 which is a retroviral vector or a lentiviral vector or a transposon.

12. A method for making a T or NK cell according to claim 1 , which comprises the step of introducing: a nucleic acid sequence according to claim 4 ; a first nucleic acid sequence and a second nucleic acid sequence as defined in claim 8 ;

and/or a first vector and a second vector as defined in claim 9 or a vector according to claim 10 or 11 , into a T or NK cell.

13. The method according to claim 12 , wherein the T or NK cell is from a sample isolated from a subject.

14. A pharmaceutical composition comprising a plurality of T or NK cells according to claim 1 .

15. A method for treating and/or preventing a disease, which comprises the step of administering a pharmaceutical composition according to claim 14 to a subject.

16. The method according to claim 15 , which comprises the following steps:

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

(ii) transduction or transfection of the T or NK cells with: a nucleic acid sequence according to claim 4 ; a first nucleic acid sequence and a second nucleic acid sequence as defined in claim 8 ; or a vector according to claim 10 ; and

(iii) administering the T or NK cells from (ii) to a the subject.

17. The method according to claim 16 , wherein the disease is a cancer.