CHIMERIC ANTIGEN RECEPTOR T CELL SWITCHES AND USES THEREOF

1 .- 60 . (canceled)

61 . A method comprising:

a. Administering a first chimeric antigen receptor-effector cell (CAR-EC) switch to a subject, wherein the first CAR-EC switch comprises:

i. a first chimeric antigen receptor-interacting domain (CAR-ID) that interacts with a chimeric antigen receptor on a CAR-EC; and

ii. a first target interacting domain (TID) comprising an unnatural amino acid, wherein the TID interacts with a first surface molecule on a target cell and wherein the TID comprises a CAR-ID attached site-specifically to the TID via the unnatural amino acid; and

b. Administering a first chimeric antigen receptor-effector cell comprising a chimeric antigen receptor that binds to the first CAR-ID of the first CAR-EC switch.

62 . The switch of claim 61 , wherein a linker site-specifically attaches the first CAR-ID to the unnatural amino acid of the first TID; and wherein, optionally, the linker comprises an aminooxy group, azide group cyclooctyne group, or a combination thereof at one or more termini.

63 . The switch of claim 61 , wherein the first CAR-ID comprises a small molecule.

64 . The switch of claim 63 , wherein the small molecule is a hapten, and wherein, optionally, the hapten is selected from fluorescein isothiocyanate (FITC) or biotin.

65 . The switch of claim 61 , wherein the first TID comprises at least an antigen-binding fragment of an antibody or at least an antigen-binding fragment of a single chain variable fragment (scFv).

66 . The switch of claim 61 , wherein the first TID 15 comprises at least an antigen binding fragment of an anti-CD19 antibody or at least an antigen-binding fragment of a single chain variable domain (scFv) of an anti-CD19 antibody.

67 . The switch of claim 61 , wherein the first TID comprises at least an antigen binding fragment of an antibody selected from the group consisting of anti-CD20, anti-CD22, anti-CD33, anti-BMSA, anti-CEA, anti-CLL1, anti-CS1, anti-EGFR, and anti-Her2 or at least an antigen binding fragment of a single chain variable domain (scFv) of an antibody selected from the group consisting of anti-CD20, anti-CD22, anti-CD33, anti-BMSA, anti-CEA, anti-CLL1, anti-CS1, anti-EGFR, and anti-Her2.

68 . The method of claim 61 , wherein the binding of the first CAR-ID on the first CAR-EC switch to the first chimeric antigen receptor on an effector cell and the binding of the first TID on the first CAR-EC switch to the first surface molecule on the target cell induces a CAR-EC-mediated immune response that is cytotoxic to the target cell.

69 . The method of claim 68 , wherein the cytotoxic response is more efficacious than a cytotoxic response induced by the same CAR-EC when combined with a similar CAR-EC switch that differs from the first CAR-EC switch only in that it comprises a CAR-ID attached via random attachment.

70 . The method of claim 61 , wherein the administration of the CAR-EC switch or the CAR-EC alone has no therapeutic effect, but wherein the administration of both the CAR-EC and the CAR-EC switch induces a therapeutic effect comprising a CAR-EC-mediated immune response that is cytotoxic to the target cell.

71 . The method of claim 61 , further comprising administering one or more second CAR-EC switch to the subject, each second CAR-EC switch comprising:

i. a second CAR-ID that interacts with a chimeric antigen receptor on an effector cell; and

ii. a second TID comprising an unnatural amino acid, wherein the second TID comprises the second CAR-ID attached site-specifically via the unnatural amino acid; and wherein the second TID interacts with a surface molecule on a target cell;

wherein the second CAR-ID comprised on each second CAR-EC switch is optionally:

(a) the same as the first CAR-ID comprised on the first CAR-EC switch or

(b) a second CAR-ID that differs from the first CAR-ID comprised on the first CAR-EC switch; provided that if the second CAR-ID differs from the first CAR-ID, the method further comprises administering a second CAR-EC comprising a chimeric antigen receptor that interacts with the second CAR-ID of the second CAR-EC switch.

72 . The method of claim 71 , wherein

(i) the first TID comprises an anti-CD20 antibody or an antigen binding portion thereof and the second TID comprises an anti-CD19 antibody or an antigen binding fragment thereof; or

(ii) the first TID comprises an anti-CD19 antibody or an antigen binding fragment thereof and the second TID comprises an anti-CD20 antibody or an antigen binding fragment thereof.

73 . The method of claim 71 , wherein the second CAR-EC switch is administered to the subject after the first CAR-EC switch.

74 . The method of claim 72 , wherein the second CAR-EC switch is administered to the subject after the subject has been diagnosed as having a modulated expression of the cell surface molecule to which the first targeting moiety binds.

75 . The method of claim 73 , wherein

(i) the first TID comprises an anti-CD20 antibody or an antigen binding fragment thereof and the second TID comprises an anti-CD19 antibody or an antigen binding fragment thereof; or

(ii) the first TID comprises an anti-CD19 antibody or an antigen binding fragment thereof and the second TID comprises an anti-CD20 antibody or an antigen binding fragment thereof.

76 . The method of claim 1 , wherein the TID comprises at least an antigen binding fragment of an anti-CD19 antibody having at least one unnatural amino acid at a position selected from:

(i) serine 202 (LCS202), glycine 68 (LCG68), threonine 109 (LCT109), and combinations thereof on the light chain of the anti-CD19 antibody or antigen binding fragment thereof;

(ii) serine 74 (HCS74), alanine 121 (HCA121), lysine 136 (HCK136) and combinations thereof on the heavy chain; or

(iii) (a) both HCK136 and LCS202 or (b) both HCS74 and LCG68.

77 . The method of claim 71 , wherein one or both of the first and second TID comprises FITC.

78 . A kit comprising:

a. a first CAR-EC switch that comprises:

i. a first CAR-ID that interacts with a chimeric antigen receptor on a CAR-EC; and

ii. a first TID comprising an unnatural amino acid, wherein the first TID interacts with a first surface molecule on a target cell and wherein the first TID comprises a CAR-ID attached site-specifically to the first TID via the unnatural amino acid;

b. a first CAR-EC comprising a chimeric antigen receptor that binds to the first CAR-ID of the first CAR-EC switch.

79 . The kit of claim 78 , further comprising one or more second CAR-EC switch, each second CAR-EC switch comprising:

i. a second CAR-ID that interacts with a chimeric antigen receptor on an effector cell; and

ii. a second TID comprising an unnatural amino acid, wherein the second TID comprises the second CAR-ID attached site-specifically via the unnatural amino acid; and wherein the second TID interacts with a surface molecule on a target cell;

wherein the second CAR-ID comprised on each second CAR-EC switch is optionally (a) the same as the first CAR-ID comprised on the first CAR-EC switch or (b) a second CAR-ID that differs from the first CAR-ID comprised on the first CAR-EC switch; and wherein, if the second CAR-ID differs from the first CAR-ID, the kit optionally further comprises a second CAR-EC comprising a chimeric antigen receptor that interacts with the second CAR-ID of the second CAR-EC switch.

80 . The kit of claim 79 , wherein

(i) the first TID comprises an anti-CD20 antibody or an antigen binding fragment thereof and the second TID comprises an anti-CD19 antibody or an antigen binding fragment thereof; or

(ii) the first TID comprises an anti-CD19 antibody or an antigen binding fragment thereof and the second TID comprises an anti-CD20 antibody or an antigen binding fragment thereof.