INDUCIBLE T CELL RECEPTORS AND USES THEREOF

Abstract

The present invention relates to (nucleic acids encoding) inducible T cell receptors (iTCRs), compositions and kits, vectors and host cells comprising such (nucleic acids encoding) inducible T cell receptors, uses thereof in preparing inducible T cell receptors and host cells comprising such T cell receptors, methods for preparing such inducible T cell receptors and for dimerizing T cell receptors, as well as medical uses of such compounds and pharmaceutical compositions comprising them, particularly for treating cancer. The present invention relates to combinations comprising one or more nucleic acid molecules, said one or more nucleic acid molecules comprising a nucleic acid sequence A encoding for a TCR alpha chain linked to a dimerization domain, and a nucleic acid sequence B encoding for a TCR beta chain linked to a dimerization domain, as well as proteins encoded by such nucleic acid molecules and corresponding uses and methods.

Claims

1. Combination comprising one or more nucleic acid molecules, said one or more nucleic acid molecules comprising: (a) a nucleic acid sequence A, comprising (i) a nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2, optionally comprising amino acid substitutions at positions 44 and/or 47 compared to SEQ ID NO: 2, and (ii) a nucleic acid sequence encoding an inducible dimerization domain being downstream linked to said nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2; and (b) a nucleic acid sequence B, comprising (i) a nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 4 comprising amino acid substitutions at positions 4, 5, 37, 63, 77 and/or 79 compared to SEQ ID NO: 4, and (ii) a nucleic acid sequence encoding an inducible dimerization domain being downstream linked to said nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 4, analogously to the localization of the dimerization domain linked to the nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2 of (a)(i), said dimerization domain corresponding to the dimerization domain linked to the nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2 of (a)(i), wherein said amino acid sequence being at least 90% identical to SEQ ID NO: 2 of (a)(i) comprises at least one, preferably at least two amino acid substitution(s) compared to SEQ ID NO: 2, and/or said amino acid sequence being at least 90% identical to SEQ ID NO: 4 of (b)(i) comprises at least one, preferably at least two, more preferably at least three amino acid substitution(s) compared to SEQ ID NO: 4.

2. The combination of claim 1, wherein the nucleic acid sequence A and the nucleic acid sequence B are comprised by separate nucleic acid molecules or comprised in one nucleic acid molecule.

3. The combination of claim 1 or 2, wherein (a) said nucleic acid sequence of (a)(i) encodes an amino acid sequence comprising at least one amino acid substitution compared to the amino acid sequence of SEQ ID NO: 2, said substitution being selected from the group consisting of: T44A and T47A; and/or (b) said nucleic acid sequence of (b)(i) encodes an amino acid sequence comprising at least one amino acid substitution compared to the amino acid sequence of SEQ ID NO: 4, said substitution being selected from the group consisting of: K4V, N5P, Y37K, L63A, S77A, and R79A, wherein preferably (c) said nucleic acid sequence of (a)(i) encodes an amino acid sequence comprising two amino acid substitutions compared to the amino acid sequence of SEQ ID NO: 2, said two substitutions being T44A and T47A; and (d) said nucleic acid sequence of (b)(i) encodes an amino acid sequence comprising three amino acid substitutions compared to the amino acid sequence of SEQ ID NO: 4, said three substitutions being K4V, N5P and Y37K or L63A, S77A, and R79A.

4. The combination of claims 1 to 3, wherein the dimerization domain is a homodimerization domain or a heterodimerization domain, preferably selected from the group consisting of ERT2, FKBP, CalcineurinA (CNA), CyP-Fas, GyrB, GAI, GID1, Snap-tag, HaloTag, eDHFR and FRB domain of mTOR.

5. An expression cassette comprising the nucleic acid sequence A and the nucleic acid sequence B as defined in any one of claims 1 to 4, or at least two expression cassettes, wherein at least one expression cassette comprises the nucleic acid sequence A as defined in any one of claims 1 to 4 and at least one expression cassette comprises the nucleic acid sequence B as defined in any one of claims 1 to 4.

6. A vector comprising one or more expression cassettes as defined in claim 5, wherein the vector is preferably a retroviral vector or a lentiviral vector.

7. Kit comprising the combination of any one of claims 1 to 4, the expression cassette of claim 6 or the vector of claim 6 and a dimerization agent corresponding to the dimerization domain linked to the nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 2 and the dimerization domain linked to the nucleic acid sequence encoding an amino acid sequence being at least 90% identical to SEQ ID NO: 4 as defined in any one of claims 1 to 5, said dimerization agent being capable of inducing dimerization of said dimerization domains, wherein the dimerization agents is preferably selected from the group consisting of 4-hydroxytamoxifen, Endoxifen, 4-(1-[4-(Dimethylaminoethoxy)phenyl]-2-phenyl-1-butenyl)phenol, AP21967, and 23,27-Epoxy-3H-pyrido[2,1-c][1,4]oxaazacyclohentriacontine, FK1012, FK506, FKCsA, Rapamycin, Coumermycin, Gibberellin, HaXS, and TMP-HTag.

8. A host cell comprising the nucleic acid sequence A and the nucleic acid sequence B as defined in any one of claims 1 to 4, the expression cassette as defined in claim 5, or the vector as defined in claim 6, wherein the host cell is preferably a T lymphocyte, more preferably a human T lymphocyte, and said host cell optionally comprises the dimerization agents as defined in claim 7.

9. Protein encoded by the nucleic acid sequence A and the nucleic acid sequence B as defined in any one of claims 1 to 4.

10. Use of a dimerization agent as defined in claim 7 for dimerizing a protein encoded by the nucleic acid sequence A and a protein encoded by the nucleic acid sequence B as defined in any one of claims 1 to 4, wherein the dimerization agent is preferably Endoxifen.

11. Method for dimerizing a protein encoded by the nucleic acid sequence A and a protein encoded by the nucleic acid sequence B as defined in any one of claims 1 to 4, comprising the step of adding the dimerization agents as defined in claim 7 to said proteins.

12. Method for preparing an inducible T cell receptor, comprising the step of introducing the nucleic acid sequence A and the nucleic acid sequence B as defined in any one of claims 1 to 4, the expression cassette as defined in claim 5, or the vector as defined in claim 6 in vitro into a host cell under conditions allowing the expression of the nucleic acid sequence A and the nucleic acid sequence B.

13. The combination as defined in any one of claims 1 to 4, the expression cassette as defined in claim 5, the vector as defined in claim 6, the host cell as defined in claim 8, or the protein as defined in claim 9 for use in T cell therapy, preferably in treating cancer.

14. The combination, expression cassette, vector, host cell, or protein of item 13, wherein said cancer is solid cancer or blood cancer.

15. Pharmaceutical composition comprising the combination as defined in any one of claims 1 to 4, the expression cassette as defined in claim 5, the vector as defined in claim 6, the host cell as defined in claim 8, or the protein as defined in claim 9.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0076] FIG. 1 shows a schematic overview of the inducible TCR. Point mutations (asterisk) are introduced in the constant (c) alpha () and beta () chains of a given TCR. Due to the mutations, the TCR alpha-CD3 and TCR beta-CD3 complexes cannot pair in the endoplasmic reticulum. Dimerizing domains (DD) or alternatively heterodimerizing domains (HD) are inserted in the c-terminal end of both constant alpha and beta chains of the same TCR. Upon introduction of the dimerizing or heterodimerizing agent (DA or HA), pairing of alpha and beta chains and subsequent formation of the functional cluster comprising CD3 (CD3) and TCR, including the CD3 zeta-chain (-chain, zeta-chain) can occur and accordingly the TCR can be expressed on the surface of the cell.

[0077] FIG. 2 shows TCR.sup. Jurkat-76 (Jurkat 76 cells are a TCR - and -derivative of the CD8-negative human T cell lymphoma Jurkat cell line, kindly provided by M. Heemskerk) cells transduced with the inducible TCR G11-3 (iTCR-G11-3, MHC-II restricted TCR) and tested by flow cytometry for membrane expression of CD3-TCR complex 6 h after induction with 10 M 4-hydroxytamoxifen (4-hydroxytamoxifen, 4-(1-[4-(Dimethylaminoethoxy)phenyl]-2-phenyl-1-butenyl)phenol, Sigma-Aldrich, stock of 5 mM in DMSO). 4-hydroxytamoxifen was diluted to 10 M in cell culture medium containing the cells (middle plots) or no 4-hydroxytamoxifen was added (No tamoxifen, far left and far right plots). Untransduced Jurkat-76 cells were used as negative control for TCR expression and Jurkat-76 tansduced with wt G11-3 (Milosevic S. et al., J Virol 2006 Nov 80(21):10357-64) were used as positive control for G11-3 TCR expression. Cells were stained with anti-CD3-PECy7 and anti panTCR-PE. Plots were generated using the analysis tool FlowJo V10.

[0078] FIG. 3a shows TCR.sup. Jurkat-76 cells transduced with iTCR-G11-3 and assessed for membrane expression of CD3-TCR complex by flow cytometry after induction with 10 M 4-hydroxytamoxifen or without tamoxifen. Untransduced TCR.sup. Jurkat-76 cells were used as negative control for TCR expression. Cells were stained with anti-CD3-PECy7 and anti-panTCR-PE and flow cytometry was performed 0.5 h, 1 h, 4 h, 6 h and 24 h after 4-hydroxytamoxifen treatment. FIG. 3b shows the kinetics of iTCR-G11-3 induction over time (0.5 h, 1 h, 4 h, 6 h and 24 h) using either 5 M or 10 M 4-hydroxytamoxifen. Cells were stained with anti-CD3-PECy7 and anti-panTCR-PE and flow cytometry was performed 0.5 h, 1 h, 4 h, 6 h and 24 h after 4-hydroxytamoxifen treatment. Graph was plotted using graphPad Prism 7. Plots were generated using the analysis tool FlowJo V10.

[0079] FIG. 4 shows Jurkat-76 transduced with iTCR-G11-3 and with inducible NFAT-responsive GFP reporter (ieGFP) and induced for 6 h with 5 M 4-hydroxytamoxifen. LCL loaded either with relevant TDAWRFAMNYPRNPT (TDA) peptide or with irrelevant PEVWILSPLLRHG (PEV) peptide were added to the cultures. The ratio of LCL:Jurkat-76 in the co-cultures was 1:1. Jurkat-76 transduced with wt (wild-type) G11-3 were used as positive control. Flow cytometry was performed 24 h after co-incubation and cells were assessed for CD3, TCR and GFP expression. Plots were generated using the analysis tool FlowJo V10.

[0080] FIG. 5a shows Jurkat-76 transduced with iTCR-G11-3 and with ieGFP and induced overnight with 1 M 4-hydroxytamoxifen or left untreated (none). LCLs loaded with irrelevant PEV peptide were added to the cultures and GFP induction was followed over time (shown are 1 h, 1.5 h and 3.5 h) using the Incucyte Zoom device (IncuCyte Zoom HD/2CLR System, Essen Bioscience). FIG. 5b shows Jurkat-76 transduced with iTCR-G11-3 and with ieGFP and induced overnight with 1 M 4-hydroxytamoxifen or left untreated (none). LCLs loaded with relevant TDA peptide were added to the cultures and GFP induction was followed over time (shown are 1 h, 1.5 h and 3.5 h) using the Incucyte Zoom device. FIG. 5c: Jurkat-76 transduced with iTCR-G11-3 and with ieGFP were induced overnight with 0.1 M, 1 M or 5 M 4-hydroxytamoxifen. LCL loaded with relevant TDA peptide were added to the cultures and GFP induction was followed using the Incucyte Zoom device for 13 h. Jurkat-76 transduced with wt-G11-3 were used as positive control. Shown are the first 14 hours of the kinetics. Graph was plotted using Excel. GFP fluorescence intensity is depicted on the y-axis as green calibration units (GCU)mm.sup.2.

[0081] FIG. 6: Jurkat-76 transduced with iTCR-G11-3 and with ieGFP were induced overnight with 0.05 M or 0.1 M 4-hydroxytamoxifen. Samples were washed and LCL loaded with relevant TDA peptide were added after 1 h, 2 h and 4 h of washing and GFP induction was followed using the Incucyte Zoom device. For the positive control (pictures in the far left column) LCL loaded with relevant TDA peptide was added to the cultures and no washing was performed.

[0082] FIG. 7a shows TCR.sup. Jurkat-76 cells transduced with either the inducible TCR iTCR NY-ESO (iTCR-NY-ESO, MHC-I restricted TCR, upper plots) or with wt-NY-ESO TCR (lower plots) and tested by flow cytometry for membrane expression of CD3-TCR complex. Transduced cells also express BFP (blue fluorescent protein, vector encoding for iTCR also contains blue fluorescent protein (mTag-BFP) as reporter gene, which is separately expressed, thus only transduced cells are BFP positive) (plots on the left). Plots on the right show CD3 and TCR staining for BFP+ cells. Cells were stained with anti-CD3-PECy7 and anti-panTCR-PE. Plots were generated using the analysis tool FlowJo V10. FIG. 7b shows TCR.sup. Jurkat-76 cells transduced with either the inducible TCR NY-ESO (iTCR-NY-ESO, MHC-I restricted TCR, upper plots) or with wt-NY-ESO TCR (lower plots) and induced with 1 M 4-hydroxytamoxifen (stock of 5 mM in DMSO). 4-hydroxytamoxifen was diluted to 1 M in cell culture medium containing the cells. Transduced cells also express BFP (plots on the left). Plots on the right show CD3 and TCR staining for BFP+ cells. Cells were stained with anti-CD3-PECy7 and anti-panTCR-PE. Plots were generated using the analysis tool FlowJo V10.

[0083] FIG. 8a: Jurkat-76 transduced with iTCR-NY-ESO-mTag-BFP (MHC-I restricted TCR) and with ieGFP were incubated with T2 cells loaded either with irrelevant VLDGLDVLL peptide or with relevant peptide SLLMWITQC. The ratio of T2:Jurkat-76 in the co-cultures was 1:1. Flow cytometry was performed 24 h after co-incubation staining for CD19 and determining blue fluorescence, fluorescence in APC and FITC channel. Gating strategy was to gate on CH19.sup. (negative) (thus excluding T2-target cells, which are CD19.sup. (positive)) and BFP.sup.+ cells and to determine fluorescence of ieGFP in FITC channel of FACS. Plots were generated using the analysis tool FlowJo V10. FIG. 8b: Jurkat-76 transduced with iTCR-NY-ESO (MHC-I restricted TCR) and with ieGFP were induced overnight with 1 M Endoxifen ((E/Z)-Endoxifen hydrochloride hydrate, Sigma-Aldrich)) and were then incubated with T2 cells loaded either with irrelevant VLDGLDVLL (T2-irr. Pept.) peptide or with relevant peptide SLLMWITQC (T2-rel. pept.). The ratio of T2:Jurkat-76 in the co-cultures was 1:1. Flow cytometry was performed 24 h after co-incubation and cells were assessed for BFP (transductants), CD3, TCR and GFP expression. Plots were generated using the analysis tool FlowJo V10.

[0084] FIG. 9: CD8.sup.+ PBL transduced with iTCR-NY-ESO (MHC-I restricted TCR) or CD8.sup.+ PBL expressing wt-NY-ESO were induced overnight with 1, 5, 10 or 20 M Endoxifen or were left uninduced (no Endoxifen). 24 h after induction T2 cells loaded with relevant peptide SLLMWITQC or irrelevant peptide VLDGLDVLL were added to the cultures. IFN- secretion was detected by standard IFN- ELISA performed with the culture supernatants 24 h after stimulation with T2 targets. Flow cytometry was performed 48 h after induction and cells were assessed for BFP (transductants), CD3 and BV6-5. Exemplary plots shown are iTCR-NY-ESO transduced CD8.sup.+ PBL without induction or with 20 M Endoxifen. Plots were generated using the analysis tool FlowJo V10. Graph was plotted using graphPad Prism 7.

[0085] FIG. 10: CD8.sup.+ PBL transduced with i-NY-ESO (MHC-I restricted TCR) or CD8.sup.+ PBL expressing wt-NY-ESO were induced for 20 h with 10 M Endoxifen (+induction) or left untreated (no induction). Cells were then incubated with T2 cells expressing NuclightRed loaded with relevant peptide (+pept) or with T2 NuclightRed cells loaded with irrelevant control peptide (+ctrl). Killing of T2 cells was followed over time using the Incucyte Zoom device. A) Pictures show 42 h after incubation of T cells and target cells. In the upper panel T cells were not induced with Endoxifen. Lower panel shows T cells that have been induced with Endoxifen. T2 NuclightRed cells appear in the middle and are dark grey. Effector cells are light grey. B) Graphs show density of T2 NuclightRed cells overtime (up to 42 h). Mock are untransduced CD8+PBL.

[0086] FIG. 11: TCR Alpha constant region using the amino-acid numbering nomenclature according to IMGT for human constant alpha region: http://www.imgt.org/IMGTrepertoire/Proteins/alleles/index.php?species=Homo%20sapiens&group=TRAC&gene=TRAC1,

[0087] FIG. 12: TCR Beta constant region using the amino acid numbering nomenclature according to IMGT for human constant beta region allele C1: http://www.imgt.org/IMGTrepertoire/Proteins/alleles/index.php?species=Homo%20sapiens&group=TRBC&gene=TRBC1.

[0088] FIG. 13: TCR.sup. Jurkat-76 cells transduced with wt TCR recognizing PRAME antigen (wt TCR) and with TCR recognizing PRAME antigen with amino acid residues 4, 5, and 37 in the Constant beta chain (SEQ ID 4) mutated, respectively to V, P and K. Mock control are Jurkat-76 TCR/ cells untransduced. The cells were assessed for CD3 and TCR expression by flow cytometry. Plots were generated using the analysis tool FlowJo V10.

[0089] FIG. 14: TCR.sup. Jurkat-76 cells containing ieGFP reporter were transduced with G11-3 TCR carrying estrogen receptor in both C terminus of Constant alpha and beta chains and with amino acid residues 4, 5, and 37 in the Constant beta chain (SEQ ID 4) mutated, respectively to V, P and K. Cells were induced with 1 M endoxifen for 24 h. Cells were then incubated with LCL cells loaded either with relevant TDAWRFAMNYPRNPT peptide (relevant) or with irrelevant PEVWILSPLLRHG peptide (irrelevant). The ratio of LCL:Jurkat-76 in the cocultures was 1:1. Flow cytometry assessment of induced eGFP was performed 24 h after coincubation. Plots were generated using the analysis tool FlowJo V10.

[0090] The following Examples illustrate the present invention, however, without limiting the scope of the invention and the claims.

EXAMPLES

Abbreviations and Synonyms

[0091] APC Antigen presenting cells [0092] BFP Blue fluorescence protein [0093] ER Endoplasmic reticulum [0094] ERT2 Estrogen receptor (mutated variant) [0095] GFP Green fluorescence protein [0096] iTCR Inducible TCR [0097] ieGFP Inducible enhanced GFP [0098] LCL Lymphoblastoid cell line [0099] On/off Inducible TCR [0100] PBL Peripheral blood lymphocytes [0101] TCR T cell receptor [0102] 4-OH-Tamoxifen 4-Hydroxytamoxifen

Example 1

Rendering a T Cell Receptor Inducible

[0103] With the goal to impair TCR alpha and beta chains pairing the inventors searched for amino acid mutations in the TCR alpha constant and TCR beta constant regions, that would impair TCR alpha and beta chains pairing but would not disturb pairing of the TCR alpha chain with CD3 epsilon and CD3 delta and pairing of the TCR beta chain with CD3 gamma and CD3 epsilon. To identify such amino acids, the inventors conducted a vast search of the literature and considered the crystal structure of known TCRs to retain unaltered interaction of TCR alpha and beta chains with CD3 subunits (Tables 1 and 2). To render the TCR in question inducible, dimerizing (e.g. ERT2) or heterodimerizing (e.g. FKBP, FRB) domains are inserted in the C-terminus of the respective mutated non-pairing alpha and beta constant regions. By exposing cells bearing this iTCR to a dimerizing agent (e.g. 4-hydroxytamoxifen, 4-(1-[4-(Dimethylaminoethoxy)phenyl]-2-phenyl-1-butenyl)phenol, Sigma-Aldrich) or a heterodimerizing agent (e.g. AP21967, 23,27-Epoxy-3H-pyrido[2,1-c][1,4]oxaazacyclohentriacontine; Sigma-Aldrich), TCR-CD3 complex should pair with TCR-CD3 complex in the endoplasmic reticulum and subsequently TCR-CD3-TCR-CD3 should be assembled with CD3 in the Golgi apparatus and transported to the cell surface (Feige M J., et al. J Biol Chem. 2015 Oct. 30; 290(44):26821-31). Once the iTCR is on the cell surface it should recognize its pMHC complex presented by antigen presenting cells (APC) equivalently to the original, non-inducible TCR (FIG. 1).

Example 2

Testing for Impairment of MHC Class Il-Restricted iTCR Alpha and Beta Chains Pairing and Induction of Alpha and Beta Pairing Using 4-hydroxytamoxifen in Jurkat-76 Cells

[0104] A synthetic cassette containing the iTCR-G11-3 was cloned into the lentiviral vector pCDH and transduced into 0.510.sup.6 TCR.sup./ Jurkat-76 cells (FIGS. 2-6). The iTCR-G11-3 TCR cassette contains the V-alpha and V-beta sequences of the MHC class II restricted TCR G11-3 (Milosevic S. et al., J Virol 2006 Nov 80(21):10357-64), the mutations in the alpha and beta-constant regions shown in Table 1 and ERT2 in the C-terminus of each alpha and beta constant regions. ERT2 is the mutated form of the human ligand-binding domain of estrogen receptor which can bind tamoxifen active metabolites but not estradiol (Feil R., et al., Biochem Biophys Res Commun. 1997 Aug. 28;237(3):752-7). The ERT2 nucleotide and amino acid sequences are depicted in SEQ ID NO: 7 and 8, respectively. Lack of expression of iTCR-G11-3 was tested by staining non-induced Jurkat cells carrying iTCR-G11-3 with anti-CD3 (CD3-PECy7, SK7, 557851, BD) and anti-TCR (panTCR-PE, IP26, B49177, Beckman Coulter) using flow cytometry. Without induction with 4-hydroxytamoxifen no CD3 or TCR could be detected on the surface of the cells. In contrast, by inducing Jurkat cells carrying iTCR-G11-3 with 10 M 4-hydroxytamoxifen both TCR and CD3 could be detected on the surface of the cells 6 h after induction (FIG. 2). To identify the earliest and latest time-points at which the surface expression of the iTCR can be detected, Jurkat cells carrying iTCR-G11-3 were induced with 5 or 10 M 4-hydroxytamoxifen and assayed for CD3 and TCR expression at 0.5 h, 1 h, 4 h, 6 h and 24 h after treatment (FIGS. 3a and 3b). Non-induced Jurkats and untransduced TCR.sup./ Jurkats were used as negative controls for TCR/CD3 surface expression. Surface iTCR expression could be detected as early as 4 h after induction and expression was sustained even 24 h later.

Example 3

Testing MHC Class Il-Restricted iTCR Function After Induction of iTCR Alpha and Beta Chains Pairing with 4-hydroxytamoxifen in Jurkat-76 Cells

[0105] As TCR transduced Jurkat cells in general do not secrete cytokines upon pMHC recognition, the inventors made use of an inducible NFAT-responsive GFP reporter cassette (ieGFP) as read out for functional TCR signaling. The ieGFP cassette was cloned in the lentiviral vector pCDH (System Biosciences) and transduced into 0.510.sup.6 TCR.sup./ Jurkat-76 cells. The same Jurkat cells carrying ieGFP were then transduced with the lentiviral vector carrying the iTCR-G11-3 cassette (FIGS. 4-6). The wt G11-3 TCR was also transduced in Jurkat cells carrying ieGFP and served as a positive control for G11-3 TCR signaling (FIGS. 4 and 5c). LCL cells (used as antigen presenting cells) loaded with either the irrelevant peptide PEV (PEVWILSPLLRHG) or with the peptide TDA (TDAWRFAMNYPRNPT) which is recognized by the G11-3 TCR were incubated with either iTCR-G11-3-ieGFP Jurkat cells or with wt-G11-3-ieGFP Jurkat cells. Peptides were loaded at a concentration of 110.sup.5M. As expected, a GFP signal, and thus functional TCR signaling, could only be seen for either Jurkat cells expressing wt-G11-3 or Jurkat cells expressing iTCR-G11-3 after induction with 5 M 4-hydroxytamoxifen and incubation with LCL+TDA (FIG. 4). Flow cytometry analyses was performed staining for anti-CD3 (CD3-PECy7, SK7, 557851, BD) and anti-TCR (panTCR-PE, IP26, B49177, Beckman Coulter).

Example 4

Determination of Speed of iTCR Signalling Post pMHC Recognition and Speed of Switch Off of TCR Signal Cascade Upon Removal of 4-Hydroxytamoxifen

[0106] To determine how fast iTCR-G11-3 can signal, 110.sup.4 Jurkat cells carrying iTCR-G11-3 and ieGFP were induced overnight (ON) with 1 M 4-hydroxytamoxifen. To monitor lack of TCR expression without induction, Jurkat cells carrying iTCR-G11-3 and ieGFP were left untreated as control. Either LCL loaded with PEV irrelevant peptide (FIG. 5a) or LCL loaded with TDA relevant peptide (FIG. 5b) were added to the cultures and GFP signal was followed over time using the Incucyte device. GFP signal starts as soon as 1 h after incubation with APC (antigen presenting cells) loaded with relevant peptide (FIGS. 5b and 5c) and the signal continues to increase up to approximately 7 h after incubation (FIG. 5c). Peptides were loaded at a concentration of 110.sup.5M. Interestingly, the GFP signal elicited by the iTCR-G11-3 TCR was always higher over time than the signal elicited by the wt-G11-3 TCR (FIG. 5c). The induction of GFP was not seen when irrelevant peptide was presented to iTCR expressing T cells on LCL serving as APCs.

[0107] To analyze how fast the iTCR can be downregulated upon removal of 4-hydroxytamoxifen, Jurkat cells expressing iTCR-G11-3 and ieGFP were first induced overnight with 0.05 M or 0.1 M 4-hydroxytamoxifen. The next day the cells were washed free of 4-hydroxytamoxifen or left unwashed (positive control) and incubated with LCL loaded with the relevant TDA peptide either 1 h, 2 h or 4 h after removal of 4-hydroxytamoxifen and subesequently GFP signal was detected using Incucyte (FIG. 6). A reduction in the GFP signal compared to the unwashed control was already visible 1 h after cells induced with 0.05 M 4-hydroxytamoxifen were washed out of the dimerizing agent and 4 h after washing out 0.1 M 4-hydroxytamoxifen. Thus, the iTCR could be quickly induced and also quickly downregulated upon removal of the dimerizing agent.

Example 5

Testing MHC Class I-Restricted iTCR Expression and Function After Induction of iTCR Alpha and Beta Chains Pairing with 4-hydroxytamoxifen in Jurkat-76 Cells

[0108] A synthetic cassette containing the iTCR-NY-ESO TCR and mTag-BFP separated by P2A was cloned into the lentiviral vector pCDH and transduced into 0.510.sup.6 TCR.sup./ Jurkat-76 cells (FIGS. 7 and 8). Since the vector encoding for the iTCR also contains the blue fluorescence protein (mTag-BFP) as reporter gene, which is separately expressed, all transduced cells are BFP positive. The iTCR-NY-ESO TCR cassette contains the V-alpha and V-beta sequences of the MHC class I restricted TCR that recognizes NY-ESO antigen (Benchmark NY-ESO TCR; cf. WO 2005/113595), the mutations in the alpha and beta-constant regions shown in Table 1 and ERT2 in the C-terminus of each alpha and beta constant regions. Lack of expression of iTCR-NY-ESO was tested by staining non-induced Jurkat cells carrying iTCR-NY-ESO with anti-CD3 and anti-TCR for flow cytometry and no CD3 or TCR could be detected on the surface of the cells without induction with 4-hydroxytamoxifen (FIG. 7a). In contrast, by inducing Jurkat cells carrying iTCR-NY-ESO with 1 M 4-hydroxytamoxifen both TCR and CD3 could be detected on the surface of the cells (FIG. 7b). Flow cytometry analyses was performed staining for anti-CD3 (CD3-PECy7, SK7, 557851, BD) and anti-TCR (panTCR-PE, IP26, B49177, Beckman Coulter).

[0109] To determine whether iTCR-NY-ESO is functional upon induction, Jurkat cells carrying ieGFP were transduced with the lentiviral vector carrying the iTCR-NY-ESO cassette. The wt NY-ESO TCR was also transduced into Jurkat cells carrying ieGFP and served as a positive control for NY-ESO TCR signaling. T2 cells loaded with either the irrelevant peptide VLDGLDVLL (FIG. 8a) or with the relevant peptide SLLMWITQC (FIG. 8b) which is recognized by the NY-ESO TCR were incubated with either iTCR-NY-ESO-ieGFP Jurkats or with wt-NY-ESO-ieGFP Jurkats. Peptides were loaded at a concentration of 110.sup.5M. As expected, a GFP signal, and thus functional TCR signaling, could only be seen for either Jurkats expressing wt-NY-ESO or Jurkats expressing iTCR-NY-ESO after induction with 1 M 4-hydroxytamoxifen and incubation with T2+ relevant peptide. Gating strategy was gating on CD19.sup.negative, BFP positive cells and subsequent determination of ieGFP fluorescence (CD19-APCeF780, HIB19, 47-0199-42, eBioscience).

Example 6

Testing MHC Class I-Restricted iTCR Expression and Function After Induction of iTCR Alpha and Beta Chains Pairing with Endoxifen in CD8.SUP.+ PBL

[0110] PBL from a healthy donor was enriched for CD8.sup.+ cells using a commercial cell isolation kit (CD8+ untouched) and transduced with the lentiviral vector carrying the iTCR-NY-ESO cassette or with the lentiviral vector carrying wt-NY-ESO as positive control. As induction of the iTCR-NY-ESO with 4-Hydroxytamoxifen did not induce iTCR-NY-ESO in PBL in any of the concentrations tried (data not shown), the inventors used another active Tamoxifen metabolite called Endoxifen. CD8.sup.+ cells carrying either iTCR-NY-ESO were induced overnight with 20 M Endoxifen or left untreated. Cells were then stained for CD3 (CD3-PECy7, SK7, 557851, BD) and the specific V-beta family BV6-5 (antibody: TRBV6-5-PE, IMMU 222, IM2292, Beckman Coulter). Treatment with Endoxifen resulted in induction of iTCR-NY-ESO on the surface of the cells (FIG. 9). Without treatment only the endogenously expressing BV6-5 positive cells can be seen.

[0111] To determine whether iTCR-NY-ESO is functional when induced in PBL, T2 cells loaded with the relevant peptide SLLMWITQC or irrelevant peptide VLDGLDVLL were incubated with 1, 5, 10 or 20 M Endoxifen-induced iTCR-NY-ESO CD8.sup.+ PBL or with uninduced iTCR-NY-ESO CD8.sup.+ PBL or with CD8.sup.+ PBL carrying wt-NY-ESO as positive control. Peptides were loaded at a concentration of 110.sup.5M. One day later, supernatant of the cultures was collected and a standard IFN- ELISA was performed. IFN- could be detected at high levels for wt-NY-ESO, irrespective of endoxifen treatment, and for iTCR-NY-ESO only after induction with Endoxifen (FIG. 9). These results show that iTCR-NY-ESO can be induced on the surface of PBL and has the same functional characteristics as the wt-NY-ESO TCR.

[0112] In a further experiment, it was found that T cells carrying i-TCR are cytotoxic and can eliminate targets. Again, CD8.sup.+ PBL transduced with i-NY-ESO (MHC-I restricted TCR) or CD8.sup.+ PBL expressing wt-NY-ESO were induced for 20 h with 10 M Endoxifen (+induction) or left untreated (no induction). Cells were then incubated with T2 cells expressing NuclightRed loaded with relevant peptide (+pept) or with T2 NuclightRed cells loaded with irrelevant control peptide (+ctrl). Killing of T2 cells was followed over time using the Incucyte Zoom device. The pictures in FIG. 10 A show 42 h after incubation of T cells and target cells. In the upper panel T cells were not induced with Endoxifen. Lower panel shows T cells that have been induced with Endoxifen. T2 NuclightRed cells appear in the middle and are dark grey. Effector cells are light grey. In FIG. 10 B, graphs show density of T2 NuclightRed cells over time (up to 42 h). In FIG. 10 the cells labelled Mock are untransduced CD8+PBL.

Example 7

Testing for CD3 and TCR Expression in TCR/ Cells Transduced with wt TCR and with TCR Carrying the Mutations K4V, N5P and Y37K in the Beta Chain (SEQ ID NO 4, see Table 2)

[0113] Jurkat-76 TCR/ were transduced with wt TCR recognizing PRAME antigen (wt TCR) and with TCR recognizing PRAME carrying amino acid mutations K4V, N5P and Y37K in the Constant beta chain (SEQ ID NO:4). Mock control are Jurkat-76 TCR/ cells untransduced. Flow cytometry was performed and cells were assessed for CD3 and TCR expression. Plots were generated using the analysis tool FlowJo V10. As can be seen from FIG. 13, the mutated TCR show no expression of CD3 and TCR, which shows that the mutated TCR cannot be expressed on the membrane.

Example 8

Mutations K4V, N5P and Y37K in the Beta Chain (SEQ ID NO 4, Table 2) Disrupt TCR Expression Which Can be Rescued by Dimerization of the Estrogen Receptors Contained in the C Terminus of the Alpha and Beta Constant Chains

[0114] Jurkat-76 containing ieGFP reporter were transduced with G11-3 TCR carrying estrogen receptor in both C terminus of Constant alpha and beta chains and with amino acid residues K4V, N5P and Y37K in the Constant beta chain (Seq ID 4, Table 2). Cells were induced with 1 M endoxifen for 24 h. Cells were then incubated with LCL cells loaded either with irrelevant peptide or with relevant peptide. The ratio of LCL:Jurkat-76 in the cocultures was 1:1. Flow cytometry was performed 24 h after coincubation and cells were assessed for eGFP expression. Plots were generated using the analysis tool FlowJo V10. FIG. 14 shows that ieGFP was expressed in response to the relevant peptide. This reveals that TCR carrying mutations in the positions 4, 5 and 37 of the beta constant chain is still functional after Endoxifen-induced dimerization. Thus, amino acid in the positions 4, 5, and 37 in the Constant beta chain (SEQ ID 4) can be mutated without disturbing TCR-CD3 complex formation after dimerization induced by Endoxifen.