Signalling system

1. A chimeric antigen receptor (CAR) system comprising;

(i) a receptor component comprising an extracellular antigen binding domain, a spacer, a transmembrane domain, and a first intracellular binding domain; and

(ii) an intracellular signalling component comprising a signalling domain and a second binding domain which specifically binds to the first intracellular binding domain of the receptor component;

wherein (i) and (ii) are separate molecules;

wherein the receptor component and signaling component are co-expressed;

wherein binding of the first and second binding domains of the CAR system is disruptable by the presence of an agent,

wherein, in the absence of the agent, the receptor component and the intracellular signalling component heterodimerize, and binding of the antigen binding domain to antigen results in signalling through the signalling domain, whereas in the presence of the agent, the receptor component and the signalling component do not heterodimerize, and binding of the antigen binding domain to antigen does not result in signalling through the signalling domain; and

wherein the first intracellular binding domain comprises Tet Repressor Protein (TetR) or a variant thereof and the second binding domain comprises Transcription inducing peptide (TiP) or a variant thereof; or wherein the first intracellular binding domain comprises TiP or a variant thereof and the second binding domain comprises TetR or a variant thereof; and the agent is tetracycline, doxycycline or minocycline or an analogue thereof.

2. The CAR system according to claim 1 , wherein the signalling domain of the intracellular signalling component comprises a single endodomain selected from CD3 zeta endodomain, CD28 endodomain, 41 BB endodomain and OX40 endodomain.

3. The CAR system according to claim 1 , wherein the signalling domain of the intracellular signalling component comprises at least one of CD3 zeta endodomain, CD28 endodomain, 41 BB endodomain and OX40 endodomain.

4. The CAR system according to claim 1 , wherein the first binding domain comprises Tet Repressor Protein (TetR) and the second binding domain comprises Transcription inducing peptide (TiP).

5. The CAR system according to claim 1 , wherein the first binding domain comprises TiP and the second binding domain comprises TetR.

6. A polynucleotide that comprises a nucleic acid sequence encoding a CAR signalling system,

wherein the CAR signalling system comprises:

(i) a receptor component comprising an extracellular antigen binding domain, a spacer, a transmembrane domain, and a first intracellular binding domain; and

(ii) an intracellular signalling component comprising a signalling domain and a second binding domain which specifically binds the first intracellular binding domain of the receptor component;

wherein the receptor component and signaling component are co-expressed;

wherein (i) and (ii) are separate molecules;

wherein binding of the first and second binding domains of the CAR system is disruptable by the presence of an agent,

wherein, in the absence of the agent, the receptor component and the intracellular signalling component heterodimerize, and binding of the antigen binding domain to antigen results in signalling through the signalling domain, whereas in the presence of the agent, the receptor component and the signalling component do not heterodimerize, and binding of the antigen binding domain to antigen does not result in signalling through the signalling domain;

wherein the first intracellular binding domain comprises Tet Repressor Protein (TetR) or a variant thereof and the second binding domain comprises Transcription inducing peptide (TiP) or a variant thereof; or wherein the first intracellular binding domain comprises TiP or a variant thereof and the second binding domain comprises TetR or a variant thereof; and the agent is tetracycline, doxycycline or minocycline or an analogue thereof; and

wherein the receptor component and signalling component are co-expressed, joined by a self-cleaving peptide which is cleaved between the receptor component and the signalling component after translation.

7. A vector comprising a polynucleotide according to claim 6 .

8. A T cell or NK cell which expresses a CAR system according to claim 1 .

9. A pharmaceutical composition comprising a plurality of T cells or NK cells that express the receptor component and the intracellular signalling component of the CAR system of claim 1 .

10. A method for treating a subject, which comprises administering a pharmaceutical composition according to claim 9 to the subject.

11. A method for treating a subject comprising:

(i) isolating of a T cell- or NK cell-containing sample;

(ii) transducing or transfecting the T cells or NK cells with a polynucleotide according to claim 6 or a vector comprising the polynucleotide; and

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

12. A method according to claim 10 , which involves monitoring toxic activity in the subject and comprises the step of administering the agent to the subject to reduce adverse toxic effects.

13. A method according to claim 11 , which involves monitoring the progression of disease and/or monitoring toxic activity in the subject and comprises the step of administering the agent to the subject to provide acceptable levels of disease progression and/or toxic activity.

14. A method according to claim 10 , wherein the subject has is cancer.

15. A method for making a T cell or NK cell, which comprises the step of introducing a polynucleotide according to claim 6 or a vector comprising the polynucleotide into a T or NK cell, wherein the T cell or NK cell expresses a CAR system,

wherein the CAR signalling system comprises:

(i) a receptor component comprising an extracellular antigen binding domain, a spacer, a transmembrane domain, and a first intracellular binding domain; and

(ii) an intracellular signalling component comprising a signalling domain and a second binding domain which specifically binds the first binding domain of the receptor component;

wherein the receptor component and signaling component are co-expressed;

wherein (i) and (ii) are separate molecules;

wherein binding of the first and second binding domains of the CAR system is disruptable by the presence of an agent,

wherein, in the absence of the agent, the receptor component and the intracellular signalling component heterodimerize, and binding of the antigen binding domain to antigen results in signalling through the signalling domain, whereas in the presence of the agent, the receptor component and the signalling component do not heterodimerize, and binding of the antigen binding domain to antigen does not result in signalling through the signalling domain; and

wherein the first intracellular binding domain comprises Tet Repressor Protein (TetR) or a variant thereof and the second binding domain comprises Transcription inducing peptide (TiP) or a variant thereof; or wherein the first intracellular binding domain comprises TiP or a variant thereof and the second binding domain comprises TetR or a variant thereof; and the agent is tetracycline, doxycycline or minocycline or an analogue thereof.

16. A method for inhibiting the CAR signalling system according to claim 1 in a subject to whom a T or NK cell that expresses said CAR system has been administered, which method comprises the step of administering the agent to the subject.