Tethered il-9 / il-9r and related engineered cells and methods

Abstract

Provided herein are recombinant fusion proteins, wherein each recombinant fusion protein comprises an IL-9, a linker, an extracellular domain, a transmembrane domain, and an interleukin 9 receptor (IL-9R) intracellular domain. Also provided herein are engineered cells expressing one or more such recombinant fusion protein.

Description

TETHERED IL-9 / IL-9R AND RELATED ENGINEERED CELLS ANDMETHODSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 666,091, filed June 28, 2024, and U.S. Provisional Application No. 63 / 740,971, filed December 31, 2024, each entitled “TETHERED IL-9 / IL-9R AND RELATED ENGINEERED CELLS AND METHODS” and the contents of which are incorporated by reference in their entireties.REFERENCE TO AN ELECTRONIC SEQUENCE LISTING

[0002] The present application is being filed along with a Sequence Listing in electronic format. The Sequence Listing is provided as a file entitled 307612001840seqlist.XML created June 26, 2025 which is 274,480 bytes in size. The information in the electronic format of the Sequence Listing is incorporated by reference in its entiretyFIELD

[0003] The present disclosure generally relates to recombinant fusion proteins and engineered cells expressing one or more such recombinant fusion proteins.BACKGROUND

[0004] Therapies that use adoptively transferred genetically engineered T cells have shown substantial anti-tumor activity in patients with hematopoietic malignancies. However, such therapies have limited benefit in patients with solid tumors. One major limitation is the poor in vivo expansion and persistence of adoptively transferred T cells. To circumvent this limitation, patients have been lymphodepleted with chemotherapy and / or radiation prior to being transferred with engineered T cells. However, some patients are too weak to receive toxic regimens such as chemotherapy and radiation. The other major limitation is that the T cells that do successfully expand and persist in vivo become terminally differentiated and dysfunctional. Thus, improved systems and engineered cells are needed to address these problems. Provided embodiments address these needs.SUMMARY

[0005] Provided herein is a recombinant fusion protein comprising (a) an IL-9 or a biologically active fragment thereof; (b) a modified IL-9 receptor (IL-9R) comprising an IL- 911 extracellular domain, an IL-9R transmembrane domain and a IL-9R intracellular domain, wherein one or both of the IL-9R extracellular domain and the IL-9R intracellular domain is a variant that comprises one or more mutations relative to the respective domain of a wild-type IL-9R; and (c) a peptide linker, wherein the IL-9 is connected to the modified IL-9R via the peptide linker.

[0006] Provided herein is a recombinant fusion protein comprising: (a) an IL-9 or a biologically active fragment thereof; (b) a modified IL-9 receptor (IL-9R) comprising an IL- 9R extracellular domain, an IL-9R transmembrane domain and a variant IL-9R intracellular domain comprising one or more mutations compared to the wild-type IL-9R intracellular domain, wherein the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways; and (c) peptide linker, wherein the IL-9 is connected to the modified IL-9R via the peptide linker.

[0007] In some embodiments, the IL-9R extracellular domain is an extracellular domain of a wild-type IL-9R.

[0008] In some embodiments, the IL-9R extracellular domain is an extracellular domain comprising a sequence of amino acids that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 54 or is 100% identical to SEQ ID NO: 54. In some embodiments, the IL-9R extracellular domain is an extracellular domain comprising the sequence of amino acids set forth in SEQ ID NO: 54.

[0009] In some embodiments, the IL-9R extracellular domain is a variant IL-9R extracellular domain comprising one or more mutations relative to the wild-type IL-9R extracellular domain. In some embodiments, the variant IL-9R extracellular domain is a truncated IL-9R extracellular domain and the one or more mutations is a deletion in which a contiguous sequence of amino acids is deleted from the N-terminus of wild-type IL-9R extracellular domain. In some embodiments, the variant IL-9R extracellular domain is a truncated IL-9R and the one or more mutations is a deletion in which a contiguous sequence of amino acids at the N-terminus is absent relative to wild-type IL-9R extracellular domain.

[0010] In some embodiments, the variant IL-9R extracellular domain lacks up to 115 contiguous amino acids from the N-terminus relative to wild-type IL-9R extracellular domainset forth in SEQ ID NO: 54. In some embodiments, the variant IL-9R extracellular domain lacks 20-108 contiguous amino acids from the N-terminus relative to wild-type IL-9R extracellular domain set forth in SEQ ID NO: 54. In some embodiments, the variant IL-9R extracellular domain lacks 70-99 contiguous amino acids from the N-terminus relative to wild-type IL-9R extracellular domain set forth in SEQ ID NO: 54. In some embodiments, the variant IL-9R extracellular domain comprises the fibronectin-type III domain corresponding to amino acids 109-219 of SEQ ID NO: 54. In some embodiments, the variant IL-9R extracellular domain lacks a contiguous sequence of amino acids 1-99 of SEQ ID NO: 54.

[0011] In some embodiments, the variant IL-9R extracellular domain is set forth by a sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 105. In some embodiments, the variant IL-9R extracellular domain is set forth in SEQ ID NO: 105.

[0012] In some of any embodiments, the IL-9R transmembrane domain is a transmembrane domain of a wild-type IL-9R.

[0013] In some of any embodiments, the wild-type IL-9R is human IL-9R.

[0014] In some of any embodiments, the wild-type IL-9R comprises the sequence as set forth in SEQ ID NO: 7.

[0015] In some of any embodiments, the IL-9R extracellular domain is an extracellular domain comprising a sequence of amino acids that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 54 or is 100% identical to SEQ ID NO: 54.

[0016] In some of any embodiments, the IL-9R extracellular domain is an extracellular domain comprising the sequence of amino acids set forth in SEQ ID NO: 54.

[0017] In some of any embodiments, the IL-9R transmembrane domain is a transmembrane domain comprising a sequence of amino acids that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 55 or is 100% identical to SEQ ID NO: 55.

[0018] In some of any embodiments, the IL-9R transmembrane domain is a transmembrane domain comprising the sequence of amino acids set forth in SEQ ID NO: 55.

[0019] Also provided herein is a recombinant fusion protein comprising (a) an IL-9 or a biologically active fragment thereof; (b) a modified IL-9 receptor (IL-9R) comprising an IL- 9R extracellular domain set forth in SEQ ID NO: 105, an IL-9R transmembrane domain setforth in SEQ ID NO:55 and an IL-9R intracellular domain; and (c) a peptide linker, wherein the IL-9 is connected to the modified IL-9R via the peptide linker.

[0020] In some such embodiments, the IL-9R intracellular domain is a wild-type IL-9R intracellular domain. In some embodiments, the wild-type IL-9R is human IL-9R. In some embodiments, the wild-type IL-9R comprises the sequence as set forth in SEQ ID NO: 7. In some embodiments, the IL-9R intracellular domain is an intracellular domain comprising a sequence of amino acids that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 56 or is 100% identical to SEQ ID NO:56. In some embodiments, the IL-9R intracellular domain is an intracellular domain comprising the sequence set forth in SEQ ID NO: 56.

[0021] In some embodiments, the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 153, 154, 155, 156, 157, 159 or 160. In some embodiments, the recombinant fusion protein comprises the amino acid sequence set forth in any one of SEQ ID NOs: 153, 154, 155, 156, 157, 159 or 160. In some embodiments, the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 161, 162, 163, 164, 165, 167 or 168. In some embodiments, the recombinant fusion protein comprises the amino acid sequence set forth in any one of SEQ ID NOs: 161, 162, 163, 164, 165, 167 or 168.

[0022] In other such embodiments, the IL-9R intracellular domain is a variant IL-9R intracellular domain comprising one or more mutations relative to the wild-type IL-9R intracellular domain, wherein the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways.

[0023] Also provided herein is a recombinant fusion protein comprising: (a) an IL-9 or a biologically active fragment thereof; (b) a modified IL-9 receptor (IL-9R) comprising an IL- 9R extracellular domain and an IL-9R transmembrane domain set forth by amino acids 1-251 of SEQ ID NO:7 and a variant IL-9R intracellular domain comprising one or more mutations compared to the wild-type IL-9R intracellular domain, wherein the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways; and (c) peptide linker, wherein the IL-9 is connected to the modified IL-9R via the peptide linker.

[0024] Provided herein is a recombinant fusion protein comprising: (a) an IL-9 or a biologically active fragment thereof; (b) a modified IL-9 receptor (IL-9R) comprising: (i) an IL-9R extracellular domain set forth by SEQ ID NO: 54; (ii) an IL-9R transmembranedomain set forth by SEQ ID NO: 55; and (iii) a variant IL-9R intracellular domain comprising one or more mutations compared to the wild-type IL-9R intracellular domain, wherein the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways; and (c) peptide linker, wherein the IL-9 is connected to the modified IL- 9R via the peptide linker.

[0025] In some of any embodiments, the variant IL-9R intracellular domain is less than 260 amino acids in length.

[0026] In some of any embodiments, the variant IL-9R intracellular domain is about 100 to 260 amino acids in length.

[0027] In some of any embodiments, the variant IL-9R intracellular domain comprises a BOX1 motif and / or a BOX2 motif.

[0028] In some of any embodiments, the variant IL-9R intracellular domain comprises a BOX2 motif.

[0029] In some of any embodiments, the variant IL-9R intracellular domain is 230 amino acids in length.

[0030] In some of any embodiments, the variant IL-9R intracellular domain is a variant of a wild-type IL-9R intracellular domain and comprises one or more mutations compared to the wild-type IL-9R intracellular domain set forth in SEQ ID NO: 56.

[0031] In some of any embodiments, the one or more mutations comprises one or more amino acid insertions, deletions, and / or substitutions.

[0032] In some of any embodiments, the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways.

[0033] In some of any embodiments, the variant IL-9R intracellular domain comprises an amino acid sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 56.

[0034] In some of any embodiments, the variant IL-9R intracellular domain comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 18-53.

[0035] In some embodiments, the variant IL-9R intracellular domain comprises the amino acid sequence of SEQ ID NO: 44.

[0036] In some of any embodiments, the variant IL-9R intracellular domain comprises an amino acid sequence of any one of SEQ ID NOs: 18-53.

[0037] In some of any embodiments, the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 57-92.

[0038] In some of any embodiments, the recombinant fusion protein comprises an amino acid sequence of any one of SEQ ID NOs: 57-92.

[0039] In some of any embodiments, the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 57, 60, 66, 67, 69, 71-75, 77, 80, 81, 82, 83, 84. In some of any embodiments, the recombinant fusion protein comprises an amino acid sequence of any one of SEQ ID NOs: 57, 60, 66, 67, 69, 71- 75, 77, 80, 81, 82, 83, 84.

[0040] In some embodiments, the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 110-145. In some embodiments, the recombinant fusion protein comprises an amino acid sequence of any one of SEQ ID NOs: 110-145.

[0041] In some embodiments, the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 110, 113, 119, 120, 122, 124-128, 130, 133, 134, 135, 136, 137. In some embodiments, the recombinant fusion protein comprises an amino acid sequence of any one of SEQ ID NOs: 110, 113, 119, 120, 122, 124-128, 130, 133, 134, 135, 136, 137.

[0042] In some embodiments, the recombinant fusion protein comprises the amino acid sequence of SEQ ID NO: 83 or SEQ ID NO: 136.

[0043] In some embodiments, the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to SEQ ID NOs: 158 or SEQ ID NO: 166. In some embodiments, the recombinant fusion protein comprises the amino acid sequence of SEQ ID NO: 158 or SEQ ID NO: 166.

[0044] In some of any embodiments, the variant IL-9R intracellular domain comprises one or more mutations that are one or more amino acid deletions with reference to wild-type IL-9R intracellular domain (SEQ ID NO: 56).

[0045] In some embodiments, the intracellular domain is a truncated IL-9R intracellular domain and the one or more deletions is a truncation that deletes a contiguous sequence of amino acids from the C-terminus of wild-type IL-9R intracellular domain.

[0046] In some of any embodiments, the variant IL-9R intracellular domain is a truncated IL-9R that lacks a contiguous sequence of amino acids at the C-terminus of wild-type IL-9R intracellular domain.

[0047] In some of any embodiments, the truncated IL-9R intracellular domain is truncated by between 62 and 99 contiguous amino acids from the C-terminus of wild-type IL- 9R intracellular domain.

[0048] In some of any embodiments, the amino acid sequence of the truncated IL-9R is set forth by a sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to any one of SEQ ID NOs: 18-39 and 42- 46.

[0049] In some of any embodiments, the amino acid sequence of the truncated IL-9R is set forth by the sequence of any one of SEQ ID NOs: 18-39 and 42-46.

[0050] In some of any embodiments, the truncated IL-9R ICD lacks amino acids 132 to 230 of SEQ ID NO:56 or lacks amino acids 134 to 230 of SEQ ID NO:56.

[0051] In some of any embodiments, the amino acid sequence of the truncated IL-9R is set forth by a sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO:43 or SEQ ID NO: 44.

[0052] In some of any embodiments, the amino acid sequence of the truncated IL-9R is set forth by the sequence of SEQ ID NO:43 or SEQ ID NO: 44.

[0053] In some of any embodiments, the recombinant fusion protein comprises an amino acid sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 82 or SEQ ID NO: 83.

[0054] In some of any embodiments, the recombinant fusion protein comprises the amino acid sequence of SEQ ID NO: 82 or SEQ ID NO: 83.

[0055] In some embodiments, the recombinant fusion protein comprises an amino acid sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 135 or SEQ ID NO: 136 or SEQ ID NO: 166. In some embodiments, the recombinant fusion protein comprises the amino acid sequence of SEQ ID NO: 135 or SEQ ID NO: 136 or SEQ ID NO: 166.

[0056] In some of any embodiments, the variant IL-9R intracellular domain comprises one or more amino acid substitutions with reference positions of wild-type IL-9R intracellular domain (SEQ ID NO: 56).

[0057] In some of any embodiments, the variant IL-9R intracellular domain comprises a STAT binding motif or a variant thereof.

[0058] In some embodiments, the STAT binding motif comprises a STAT1, STAT3, and / or STAT5 binding motif.

[0059] In some of any embodiments, the STAT binding motif comprises YLPQ (SEQ ID NO: 171).

[0060] In some of any embodiments, the STAT binding motif comprises a variant STAT binding motif.

[0061] In some of any embodiments, the variant STAT binding motif comprises YRPQ (SEQ ID NO: 94).

[0062] In some of any embodiments, the variant STAT binding motif comprises YLPL (SEQ ID NO: 95).

[0063] In some of any embodiments, the variant STAT binding motif comprises YLKQ (SEQ ID NO: 96).

[0064] In some of any embodiments, the variant STAT binding motif comprises FLPQ (SEQ ID NO: 97).

[0065] In some of any embodiments, the variant IL-9R intracellular domain or variant thereof comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 47-53. In some of any embodiments, the variant IL-9R intracellular domain comprises an amino acid sequence of any one of SEQ ID NOs: 47-53.

[0066] In some embodiments, the recombinant fusion protein comprises an amino acid sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to any one of SEQ ID NOs:86-92 or 139-145. In some embodiments, the recombinant fusion protein comprises the amino acid sequence of any one of SEQ ID NOs:86-92 or 139-145.

[0067] In some of any embodiments, the IL-9 or the biologically active fragment thereof is wild-type IL-9.

[0068] In some of any embodiments, the wild-type IL-9 is human IL-9.

[0069] In some of any embodiments, the IL-9 comprises an amino acid sequence at least about 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to the sequence as set forth in SEQ ID NO: 8.

[0070] In some of any embodiments, the IL-9 comprises the amino acid sequence set forth in SEQ ID NO: 8.

[0071] In some embodiments, the IL-9 comprises an amino acid sequence at least about 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to the sequence as set forth in SEQ ID NO: 185. In some embodiments, the IL-9 comprises the amino acid sequence set forth in SEQ ID NO: 185.

[0072] In some of any embodiments, the IL-9 is encoded by a nucleic acid sequence that is at least about 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to the nucleic acid sequence as set forth in SEQ ID NO: 6.

[0073] In some of any embodiments, the IL-9 comprises the nucleic acid sequence set forth in SEQ ID NO: 6.

[0074] In some of any embodiments, the linker is a peptide linker.

[0075] In some of any embodiments, the linker is a flexible linker.

[0076] In some of any embodiments, the linker is 5 to 30 amino acids in length.

[0077] In some of any embodiments, the linker is 12 to 26 amino acids in length.

[0078] In some of any embodiments, the linker is 15 to 20 amino acids in length.

[0079] In some of any embodiments, the linker is a GS linker.

[0080] In some of any embodiments, the linker comprises the sequence GS, GGS, GGGGS (SEQ ID NO: 10), GGGGGS (SEQ ID NO: 11) or combinations thereof.

[0081] In some of any embodiments, the linker comprises (GGS)n, wherein n is 1 to 10.

[0082] In some of any embodiments, the linker comprises (GGGGS)n (SEQ ID NO: 12), wherein n is 1 to 6.

[0083] In some of any embodiments, the linker comprises (GGGGGS)n (SEQ ID NO: 13), wherein n is 1 to 5.

[0084] In some embodiments, the linker is (GGGGS)2 (SEQ ID NO: 106).

[0085] In some of any embodiments, the linker is (GGGGS)3 (SEQ ID NO: 14).

[0086] In some embodiments, the linker is (GGGGS)4 (SEQ ID NO: 107).

[0087] In some of any embodiments, the linker is (GGGGS)5 (SEQ ID NO: 15).

[0088] Provided herein is a recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 136. In some embodiments, the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQID NO: 136. In some embodiments, the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 136.

[0089] Provided herein is a recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 162. In some embodiments, the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQ ID NO: 162. In some embodiments, the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 162.

[0090] Provided herein is a recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 164. In some embodiments, the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQ ID NO: 164. In some embodiments, the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 164.

[0091] Provided herein is a recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 166. In some embodiments, the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQ ID NO: 166. In some embodiments, the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 166.

[0092] Provided herein is a recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 167. In some embodiments, the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQ ID NO: 167. In some embodiments, the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 167.

[0093] Provided herein is a recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 168. In some embodiments, the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQ ID NO: 168. In some embodiments, the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 168.

[0094] In some of any of the provided embodiments, the recombinant fusion protein comprises an N-terminal signal peptide. In some embodiments, the signal peptide is MLLAMVLTSALLLCSMAG (SEQ ID NO: 108).

[0095] In some of any of the provided embodiments, the recombinant fusion protein is capable of associating with the common receptor gamma chain (common yC) when therecombinant fusion protein is engineered into a cell expressing common yC. In some embodiments, the cell is a lymphocyte. In some embodiments, the cell is a T cell.

[0096] In some of any of the provided embodiments, the recombinant fusion protein constitutively induces signaling through STAT1, STAT3, and / or STAT5 pathways in the absence of added IL- 9.

[0097] Also provided herein is a nucleic acid sequence encoding a recombinant fusion protein of any of embodiment.

[0098] Also provided herein is a polynucleotide construct comprising in 5’ to 3’ order (a) a tethered IL-9 / IL-9R transgene sequence comprising a nucleotide sequence encoding a recombinant fusion protein of some of any embodiments and (b) at least one additional transgene sequence, wherein the tethered IL-9 / IL-9R transgene sequence and the at least one additional transgene sequence are separated by a multicistronic linker sequence.

[0099] Also provided herein is a polynucleotide construct comprising in 5’ to 3’ order (a) at least one additional transgene sequence and (b) a tethered IL-9 / IL-9R transgene sequence comprising a nucleotide sequence encoding a recombinant fusion protein of some embodiments, wherein the at least one additional transgene sequence and the tethered IL- 9 / IL-9R transgene sequence are separated by multicistronic linker sequence.

[0100] In some of any embodiments, the multicistronic linker sequence is a nucleotide sequence encoding a cleavage site sequence.

[0101] In some of any embodiments, the multicistronic linker is a P2A linker.

[0102] In some of any embodiments, the multicistronic linker sequence is a nucleotide sequence with at least 85% identity to SEQ ID NO: 99.

[0103] In some of any embodiments, the multicistronic linker sequence is a nucleotide sequence set forth in SEQ ID NO: 99.

[0104] In some of any embodiments, the multicistronic linker sequence is a nucleotide sequence which encodes an amino acid with at least 85% identity to SEQ ID NO: 98.

[0105] In some of any embodiments, the tethered IL-9 / IL-9R transgene sequence and the at least one additional transgene sequence are controlled by the same or a different promoter.

[0106] In some of any embodiments, the tethered IL-9 / IL-9R transgene sequence and the at least one additional transgene are controlled by the same promoter.

[0107] In some of any embodiments, the promoter is an EF-la promoter.

[0108] In some of any embodiments, the at least one additional transgene sequence encodes an engineered receptor.

[0109] In some embodiments, the engineered receptor is a chimeric antigen receptor (CAR).

[0110] Provided herein is a vector, comprising the nucleic acid sequence of some embodiments.

[0111] Also provided herein is a vector, comprising the polynucleotide of some of any embodiments.

[0112] In some of any embodiments, the vector is a viral vector.

[0113] In some embodiments, the viral vector is a lentiviral vector.

[0114] Provided herein is a method of engineering cells, the method comprising introducing the nucleic acid of some embodiments to a cell.

[0115] Provided herein is a method of engineering cells, the method comprising introducing the polynucleotide construct of some of any embodiments to a cell.

[0116] Provided herein is a method of engineering cells, the method comprising introducing the vector of some of any embodiments to a cell.

[0117] In some of any embodiments, the cell is an immune cell.

[0118] In some of any embodiments, the cell is a lymphocyte.

[0119] In some of any embodiments, the lymphocyte is a T lymphocyte.

[0120] In some of any embodiments, the T lymphocyte is a CD8+ cytotoxic T lymphocyte.

[0121] In some of any embodiments, the lymphocyte is a Natural Killer (NK) cell.

[0122] In some of any embodiments, the cell is a primary cell from a subject.

[0123] In some of any embodiments, the subject is human.

[0124] In some of any embodiments, the cell is a derived from a stem cell, optionally an induced pluripotent cell.

[0125] In some of any embodiments, the cell is a hypoimmune cell for allogeneic cell therapy.

[0126] In some of any embodiments, the method comprising prior to the introducing, stimulating the cells with a stimulatory reagent.

[0127] In some of any embodiments, the method further comprising expanding the cells after the introducing.

[0128] Provided herein is a cell comprising the recombinant fusion protein of some of any embodiments.

[0129] Provided herein is a cell comprising the nucleic acid of some embodiments.

[0130] Provided herein is a cell comprising the polynucleotide construct of some of any embodiments.

[0131] Provided herein is a cell comprising the vector of some of any embodiments.

[0132] In some of any embodiments, the cell is an immune cell.

[0133] In some of any embodiments, the cell is a lymphocyte.

[0134] In some of any embodiments, the lymphocyte is a T lymphocyte.

[0135] In some of any embodiments, the T lymphocyte is a CD8+ cytotoxic T lymphocyte.

[0136] In some of any embodiments, the lymphocyte is a Natural Killer (NK) cell.

[0137] In some of any embodiments, the cell is a primary cell from a subject.

[0138] In some of any embodiments, the subject is human.

[0139] In some of any embodiments, the cell is a derived from a stem cell, optionally an induced pluripotent cell.

[0140] In some of any embodiments, the cell is a hypoimmune cell for allogeneic cell therapy.

[0141] In some of any embodiments, the recombinant fusion protein is a transmembrane protein expressed on the surface of the cell, wherein the IL-9 is exposed on the outside of the cell.

[0142] In some of any embodiments, the cell further comprises an engineered receptor.

[0143] In some of any embodiments, the engineered receptor is a chimeric antigen receptor (CAR) or a T cell receptor (TCR).

[0144] In some of any embodiments, the engineered receptor is a CAR.

[0145] In some of any embodiments, the cell exhibits an increase in one or more of STAT1, STAT3, and / or STAT5 activation as compared to a similar cell that does not comprise the recombinant fusion protein.

[0146] In some of any embodiments, the cell exhibits an increase in STAT1 activation as compared to a similar cell that does not comprise the recombinant fusion protein.

[0147] In some of any embodiments, the cell exhibits an increase in STAT3 activation as compared to a similar cell that does not comprise the recombinant fusion protein.

[0148] In some of any embodiments, the cell exhibits an increase in STAT5 activation as compared to a similar cell that does not comprise the recombinant fusion protein.

[0149] In some of any embodiments, the cell exhibits an increase in CD45RA expression as compared to a similar cell that does not comprise the recombinant fusion protein.

[0150] In some of any embodiments, the cell exhibits an increase in CD27 expression as compared to a similar cell that does not comprise the recombinant fusion protein.

[0151] In some of any embodiments, the cell exhibits an increase in CD45RA expression and CD27 expression as compared to a similar cell that does not comprise the recombinant fusion protein.

[0152] In some of any embodiments, the cell exhibits a decrease in CD39 expression as compared to a similar cell that does not comprise the recombinant fusion protein.

[0153] In some of any embodiments, the cell exhibits an increase in interferon gamma (IFN-y), tumor necrosis factor alpha (TNFa), IL-2, and / or IL- 10 secretion as compared to a similar cell that does not comprise the recombinant fusion protein.

[0154] Provided herein is a population cells comprising a plurality of the cells of some of any embodiments.

[0155] Provided herein is a composition, comprising the population of cells of some embodiments.

[0156] In some embodiments, the composition further comprising a pharmaceutically acceptable.

[0157] Provided herein is a method of enhancing cell function comprising culturing a cell of some of any embodiments or a population of cells of some embodiments, wherein the IL-9 of the recombinant fusion protein constitutively induces intracellular signaling by the modified IL-9R.

[0158] In some embodiments, the intracellular signaling phosphorylates one or more of STAT1, STAT3 or STAT5.

[0159] In some of any embodiments, the intracellular signaling phosphorylates each of STAT1, STAT3 or STAT5.

[0160] In some of any embodiments, the cell or population of cells are T cells and the constitutive signaling promotes a stem-like memory T cell phenotype or naive-like T cell phenotype.

[0161] In some of any embodiments, the constitutive signaling enhances the percentage of cells of the population of cells that have a stem-like memory T cell phenotype or naive-like phenotype.

[0162] In some of any embodiments, the constitutive signaling enhances the percentage of cells that are positive for CD45RA+ and CD27+.

[0163] In some of any embodiments, the cell or population of cells are T cells and the constitutive signaling promotes T cell proliferation.

[0164] In some of any embodiments, the cell or population of cells are T cells and the constitutive signaling promotes IFN-gamma production.

[0165] In some of any embodiments, the culturing further comprising contacting the cell or population of cells with a cell- stimulating agent.

[0166] In some embodiments, the cell or population of cells comprise an engineered receptor directed against a target antigen and the cell-stimulating agent comprises the target antigen.

[0167] In some embodiments, the cell-stimulating agent is a target antigen-expressing cell.

[0168] In some of any embodiments, the method is carried out in vitro or ex vivo.

[0169] In some of any embodiments, the method is carried out in vivo in a subject, wherein the cell or population of cells are administered to the subject.

[0170] In some of any embodiments, the subject has a disease or condition and the method treats the disease or condition in the subject.

[0171] Provided herein is a method of treating a disease or condition in a subject, comprising administering to the subject a dose of cells of the composition of some of any embodiments.

[0172] In some of any embodiments, the disease or condition is a cancer.

[0173] In some of any embodiments, the engineered cell of the pharmaceutical composition expresses an engineered receptor that binds to an antigen expressed on a cell of the cancer.

[0174] In some of any embodiments, the engineered receptor is a chimeric antigen receptor.

[0175] In some embodiments, the engineered receptor is a T cell receptor.BRIEF DESCRIPTION OF THE DRAWINGS

[0176] FIG. 1 shows the amount of phosphorylated STAT1, STAT3, and STAT5 for CAR T cells alone or co-expressing IL-9R untreated or IL-9R treated with IL-9 for 20 minutes or 120 minutes.

[0177] FIG. 2 shows a schematic of the tethered IL9R / IL9 where the IL-9R (e.g., wild type or a variant thereof) couples with the common receptor gamma chain (common yC) when it is present, and the linked IL-9 is capable of activating the receptor.

[0178] FIGS. 3A-3C show the amount of cells that are positive for phosphorylated STAT1, STAT3, and STAT5. FIG. 3A shows the amount of cells that are positive for phosphorylated STAT1, STAT3, and STAT5 for cells that were un-transduced or transduced with various transgenes including a CAR alone or transduced with a CAR and an additional transgene as described in Table E2, such as wild- type IL9R or a tethered IL9R / IL9 (designated 9RC_1), in some cases with added exogenous IL9 . FIG. 3B shows the amount of cells that are positive for phosphorylated STAT1, STAT3, and STAT5, where the cells were not stimulated and were un-transduced, transduced with a CAR alone, or transduced with a CAR and the tethered IL-9 / IL-9R (9RC_1). FIG. 3C shows the amount of cells that are positive for phosphorylated STAT1, STAT3, and STAT5 where the cells were stimulated with target cells and were un-transduced, transduced with a CAR alone, or transduced with a CAR and the tethered IL-9 / IL-9R (9RC_1). In FIG. 3A, the arrow represents the condition in which the cells express a CAR and the tethered IL9-IL9R fusion protein with full wildtype (WT) IL9R (9RC_1) as compared to other conditions in which cells express alternative IL9R signaling receptors or in which soluble IL9 was added.

[0179] FIGS. 4A-4F show cytokine and cell phenotyping for T cells that were untransduced (UTD), transduced with a CAR, or transduced with a CAR and an additional cytokine receptor transgene, including a CAR with a tethered IL9R / IL9 (9RC_1), a CAR with wild-type (WT) IL-9R (CAR-2A-WT9R), a CAR with a constitutively active chimeric cytokine receptor for IL- 15 (TURBO 15-30), or a CAR with a constitutively active IL-7 signaling cytokine receptor (C7R). FIG. 4A shows the percent (%) of CD8+ T cells that stained positive by flow cytometry for IFNy. FIG. 4B shows the number of T cells that stained positive by flow cytometry for CD45RA and CD27. FIG. 4C shows the percent (%) of T cells that stained positive by flow cytometry for CD45RA and CD27. FIG. 4D shows the total number of CD8+ T cells for each group of T cells that were transduced. FIG. 4Eshows representative flow plots for staining with CD45RA and CD27. FIG. 4F shows the percent (%) of T cells that stained positive by flow cytometry IFNy, TNFa, and IL-2.

[0180] FIGS. 5A-5F show the amount of phosphorylated STAT1, STAT3, and STAT5 for various tethered IL-9 / IL-9R with variant intracellular domains (ICD) compared to the amount of phosphorylated STAT1, STAT3, and STAT5 seen in tethered IL-9 / IL-9R with a wild-type ICD (CAR-P2A-IL9-G4S3-Flag-wt9R; designated “9RC_1”). FIGS. 5A-5C show the amount of phosphorylated STAT1, STAT3, and STAT5, respectively, for each of the tethered IL-9 / IL-9R with variant ICD relative to tethered IL-9 / IL-9R with a wild-type ICD using unstimulated T cells. FIGS. 5D-5F show the amount of phosphorylated STAT1, STAT3, and STAT5, respectively, for each of the tethered IL-9 / IL-9R with variant ICD relative to tethered IL-9 / IL-9R with a wild-type ICD using T cells stimulated with target cells.

[0181] FIGS. 6A-6B show CAR expression and IL-9R expression for T cells that were transduced with a CAR or transduced with a CAR and an additional tethered IL9 / IL9R transgene. FIG. 6A shows the percent (%) of CAR expressing T cells in T cells transduced with a CAR and a tethered IL9 / IL-9R, either 9RC_1 or 9RC_5. FIG. 6B shows the percent (%) of T cells expressing the tethered IL9 / IL-9R in the same T cells as determined by staining for FLAG tag.

[0182] FIG. 7A displays the amount of phosphorylated STAT1, STAT3, and STAT5 for T cells that were transduced with the CAR alone, or transduced with the CAR and wild-type IL-9R and added IL-9 (WT IL-9R + IL-9); the CAR and wild-type IL-9R (WT IL-9R; designated as 9RC_1); the CAR and tethered IL-9 / IL-9R with the variant large D2’ ICD (designated as 9RC_5); the CAR and tethered IL-9 / IL-9R with the variant large D2 ICD.; or the CAR and tethered IL-9 / IL-9R with a full IL9R including wild- type ICD.

[0183] FIG. 7B shows the percent of T cells that stained positive for IL- 10, IL-2, TNFa, and IFNy using flow cytometry, where the T cells were transduced with the CAR alone, the CAR and tethered IL-9 / IL-9R with the variant large D2’ ICD (9RC_5), or the CAR and tethered IL-9 / IL-9R with the full IL9R including wild-type ICD (9RC_1).

[0184] FIG. 7C shows cytokine phenotyping for T cells that were transduced with a CAR alone (“CAR only”) or the CAR and tethered IL-9 / IL-9R with the variant large D2’ ICD (“9RC_5”), or the CAR and tethered IL-9 / IL-9R with the full IL9R including wild-type ICD(“9RC_1”). The percent (%) of CD8+ T cells that stained positive by flow cytometry for IFNy, IL-2, IL- 10, and TNF-alpha.

[0185] FIG. 8 shows T cells from transduced with the CAR alone, the CAR and C7R, the CAR and the CAR and tethered IL-9 / IL-9R with the variant large D2’ ICD (9RC_5, or the CAR and tethered IL-9 / IL-9R with the full IL9R including wild-type ICD (9RC_1) incubated with target cells (cells that express an antigen of the CAR) with the persistence of the T cells measured over the course of three weeks of incubation with the target cells by counting the T cells once a week and plotting them as a fraction of the input cells.

[0186] FIGS. 9A-9C shows CD8 T cell counts (FIG. 9A), the percent of cells that express CD39 measured by flow cytometry (FIG. 9B), and the percent of cells that are CD45RA and CD27 positive measured by flow cytometry (FIG. 9C) for un-transduced T cells or T cells transduced with a CAR alone or a CAR and wild-type IL-9R and added (WT IL-9R + IL-9) IL-9; the CAR and wild-type IL-9R (WT IL-9R); the CAR and tethered IL- 9 / IL-9R with the variant large D2’ ICD (9RC_5); or the CAR and tethered IL-9 / IL-9R with a full IL9R including wild-type ICD (9RC_1).

[0187] FIG. 10 shows a killing assay where T cells that were un-transduced (UTD), transduced with a CAR alone, or transduced with a CAR and additional transgenes, CAR- IL18, CAR-IL18DR or the CAR and tethered IL-9 / IL-9R with the variant large D2’ ICD (9RC_5), were incubated with target cells that expressed an antigen recognized by the CAR and the number of target cells was measured over 310 hours.

[0188] FIG. 11A shows a killing assay where T cells that were un-transduced (UTD), transduced with a CAR alone, or transduced a CAR and additional transgenes, CAR-IL18, CAR-IL18DR or the CAR and tethered IL-9 / IL-9R with the variant large D2’ ICD (9RC_5), were incubated with target cells that expressed an antigen recognized by the CAR and the number of target cells was measured over 310 hours. FIG. 11B shows the number of live CD8+ T cells for each group of T cells at the end of the killing assay in FIG. 11A.

[0189] FIGS. 12A-12B shows a killing assay where T cells that were un-transduced (UTD), transduced with the CAR alone, or transduced with the CAR and the tethered IL9 / IL- 9R with the large D2’ ICD (9RC_5) were incubated with target cells that expressed an antigen recognized by the CAR and the number of target cells was measured over 600 hours. FIG. 12B shows a similar killing assay with results for T cells that were un-transduced (UTD), transduced with the CAR alone, transduced with the CAR and the tethered IL9 / IL-9Rwith the large D2’ ICD (9RC_5), or transduced with the CAR and the wildtype tethered IL9 / IL-9R (9RC_1).

[0190] FIG. 13 shows a killing assay where T cells that were un-transduced (UTD), transduced with the CAR alone (CAR), transduced with the CAR and an IL 18 receptor (CAR-IL18DR), or transduced with the CAR and the tethered IL9 / IL-9R with the large D2’ ICD (9RC_5) were incubated with target cells that expressed an antigen recognized by the CAR and the number of target cells was measured over 484 hours, where the order of the CAR and the tethered IL9 / IL-9R with the large D2’ ICD were changed so that in one sample, the CAR was upstream of the tethered IL9 / IL9R after the promoter (CAR-9RC_5) and in the other the tethered IL9 / IL-9R with the large D2’ ICD was upstream of the CAR after the promoter (9RC_5-CAR).

[0191] FIGS. 14A-14B show efficacy and survival probability in mice treated with cells that were un-transduced (UTD), transduced with a CAR alone, or transduced with a CAR and IL-18 (CAR-IL18), the CAR and tethered IL-9 / IL-9R with the variant large D2’ ICD (9RC_5); or the CAR and tethered IL-9 / IL-9R with a full IL9R including wild-type ICD (9RC_1). FIG. 14A shows tumor volume in mice after treatment with cells expressing lentiviral constructs over 58 days. FIG 14B shows radiance measurements in treated mice over 58 days.

[0192] FIGS. 15A-15C show expression of tethered IL9R ECD constructs, including tethered IL-9R / IL9 constructs with variant (e.g., truncated) extracellular domains (ECDs), in transduced T cells as determined by flow cytometry based on detecting the GS linker.

[0193] FIG. 16 shows the amount of phosphorylated STAT1, STAT3, and STAT5 for T cells that were untransduced (no plasmid), or transduced with the CAR, the CAR and wildtype IL-9R, the CAR and tethered IL-9 / IL-9R truncated ECD variants, or the CAR and tethered IL-9 / IL-9R with a full IL9R with wild-type ICD (9RC_1).

[0194] FIG. 17 shows cell phenotyping for T cells that were transduced with a CAR (“CAR”), transduced with a CAR and an additional cytokine receptor transgene IL18, transduced with the CAR and tethered IL-9 / IL-9R variants: tethered IL-9 / IL-9R with the variant large D2’ ICD (9RC_5), or ECD variants 9RC ECD_1414, or 9RC ECD_18. The plot shows the percent (%) of CD45RA+ CD27+ T cells that stained positive by flow cytometry of G4S+CD8+ cells.

[0195] FIG. 18 shows a killing assay where T cells that were un-transduced (UTD), transduced with the CAR alone (CAR), transduced with the CAR and an IL 18 receptor (CAR-IL18), or transduced with the CAR and tethered IL-9 / IL-9R variants: tethered IL-9 / IL- 9R with the variant large D2’ ICD (9RC_5), or ECD variants 9RC ECD_14, or 9RC ECD_18. These T cells were incubated with target cells that expressed an antigen recognized by the CAR and the number of target cells was measured over 6 days.

[0196] FIG. 19 shows efficacy and survival probability in mice treated with cells that were un-transduced (UTD), transduced with a CAR alone, or transduced with a CAR and IL- 18 (CAR-IL18), the CAR and tethered IL-9 / IL-9R variants: tethered IL-9 / IL-9R with the variant large D2’ ICD (9RC_5), or ECD variants 9RC ECD_14, or 9RC ECD_18. FIG. 19 shows tumor volume in mice after treated with cells expressing lentiviral constructs.DETAILED DESCRIPTION

[0197] Provided herein are recombinant fusion proteins capable of driving interleukin-9 (IL-9) receptor (IL-9R) signaling in the absence of its external cytokine ligand (i.e., constitutively active). These recombinant fusion proteins comprise an IL-9 that is tethered to an IL-9R via a linker that connects the IL-9 and IL-9R together. These recombinant fusion proteins comprise an intracellular domain derived from the intracellular domain of human IL- 9 receptor alpha (IL-9Ra), which can activate STAT1, STAT3, and STAT5 and trigger a strong STAT signal cascade. These recombinant fusion proteins also comprise various modifications to the IL-9R intracellular domains. Immune cells such as T cells expressing these recombinant fusion proteins are advantageous because such T cells assume characteristics of stem memory T cells without exhibiting signs of malignant transformation. Such T cells can also express higher amounts of cytokines or different cytokine profiles compared to T cells which do not express the recombinant fusion proteins. Such T cells can be used in adoptive immunotherapy. T cells that express the recombinant fusion proteins can express additional recombinant proteins. The additional recombinant proteins may include recombinant antigen receptors (i.e., chimeric antigen receptors (CARs)). T cells that express recombinant fusion proteins and a recombinant antigen receptor may be less likely to display an exhausted phenotype than T cells that express the recombinant antigen receptor alone. T cells that express recombinant fusion proteins and a recombinant antigen receptor may be more active than T cells that express the recombinant antigen receptor alone.

[0198] In some embodiments, the mechanism of constitutive activation comprises tethering or connecting an IL-9 to an IL-9R, such as via a linker that joins the two proteins. In some embodiments, tethering IL-9 to IL-9R induces IL-9R signaling through STAT proteins. In some embodiments, tethering IL-9 to IL-9R maintains IL-9R signaling over time.

[0199] Adoptively transferred genetically engineered immune cells (e.g., T cells) have shown substantial anti-tumor activity in patients with hematopoietic malignancies but have limited efficacy in solid tumors. This is due to the immunosuppressive environment of solid tumors, the inefficient infiltration of solid tumors, and chronic antigen stimulation, which leads to a lack of persistence and / or efficacy. In some cases, multipotency and replicative potential are also diminished. Thus, there is a need for compositions and / or methods that reduce or eliminate immune cell exhaustion, lack persistence, and / or decreased efficacy.

[0200] The provided disclosure addresses these needs. The present disclosure demonstrates that the provided recombinant fusion proteins which comprise IL-9 tethered or linked the IL-9 receptor or modified (e.g., truncated) variants thereof, even in the absence of ligand, have the ability to constitutively activate cells in which they are expressed, such as T cells. In some embodiments, the recombinant fusion protein is a tethered IL-9 / IL-9R cytokine receptor which comprises an IL-9 tethered to an IL-9R with a linker. In some embodiments, the activation triggers a strong STAT signal cascade where STAT1, STAT3, and STAT5 can all be activated. In some embodiments, the activation has the ability to result in T cells that overcome T cell exhaustion by polarizing T cells toward a naiver phenotype, increase T cell killing abilities, and / or increase the production of cytokines or change the cytokine profile of the T cells. Thus, the present disclosure demonstrates that the tethered IL-9 / IL-9R disclosed herein has the potential to reprogram and alter the phenotype of immune cells to overcome exhaustion, which can improve anti-tumor activity in solid tumors.

[0201] In some cases, genetically engineering immune cells (e.g., T cells) have low transduction efficiency, which can make engineering T cells for anti-tumor activity in patients a challenge. This may be due in part to the large size of the vector / polynucleotide used to transduce the immune cells. Thus there is a need for compositions, methods, and / or vectors that have increased transduction efficiency.

[0202] The provided disclosure addresses these needs. Among the provided embodiments, the present disclosure demonstrates that certain provided recombinant fusion proteins that comprise a tethered IL-9 / IL-9R comprising a variant (e.g., truncated) IL-9Rextracellular domain and / or a variant (e.g., truncated) IL-9R intracellular domain has increased transduction efficiency compared to a tethered IL-9 / IL-9R with a full wild-type IL9R, including a wild-type extracellular domain and wild-type IL-9R intracellular domain.

[0203] In some embodiments, the tethered IL-9 / IL-9R comprises a variant (e.g., truncated) IL-9R with a variant (e.g., truncated) IL-9R extracellular domain. In some embodiments, the tethered IL-9 / IL-9R with a variant IL-9R extracellular domain has increased STAT1, STAT3, and / or STAT5 signaling compared to a tethered IL-9 / IL-9R with a full wild-type IL-9R containing a wild-type IL-9R intracellular domain. In some embodiments, the tethered IL-9 / IL-9R with a variant IL-9R extracellular domain has improved transduction efficiency of cells, such as T cells, compared to a tethered IL-9 / IL-9R with a full wild-type IL-9R containing a wild-type IL-9R extracellular domain.

[0204] In some embodiments, the tethered IL-9 / IL-9R comprises a variant (e.g, truncated) IL-9R with a variant (e.g., truncated) IL-9R intracellular domain. In some embodiments, the tethered IL-9 / IL-9R with a variant IL-9R intracellular domain has increased STAT1, STAT3, and / or STAT5 signaling compared to a tethered IL-9 / IL-9R with a full wild-type IL-9R containing a wild-type IL-9R intracellular domain. In some embodiments, the tethered IL-9 / IL-9R with a variant IL-9R intracellular domain has improved transduction efficiency of cells, such as T cells, compared to a tethered IL-9 / IL-9R with a full wild-type IL-9R containing a wild-type IL-9R intracellular domain.

[0205] In some embodiments, the tethered IL-9 / IL-9R comprises a variant (e.g, truncated) IL-9R with a variant (e.g., truncated) IL-9R extracellular domain and a variant (e.g., truncated) IL-9R intracellular domain. In some embodiments, the tethered IL-9 / IL-9R with a variant IL-9R extracellular domain and intracellular domain has increased STAT1, STAT3, and / or STAT5 signaling compared to a tethered IL-9 / IL-9R with a full wild-type IL- 9R. In some embodiments, the tethered IL-9 / IL-9R with a variant IL-9R extracellular domain and intracellular domain has improved transduction efficiency of cells, such as T cells, compared to a tethered IL-9 / IL-9R with a full wild-type IL-9R.

[0206] All publications, including patent documents, scientific articles and databases, referred to in this application are incorporated by reference in their entirety for all purposes to the same extent as if each individual publication were individually incorporated by reference. If a definition set forth herein is contrary to or otherwise inconsistent with a definition set forth in the patents, applications, published applications and other publications that are hereinincorporated by reference, the definition set forth herein prevails over the definition that is incorporated herein by reference.

[0207] The section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.I. TETHERED IL-9 / IL-9R

[0208] Provided herein is a recombinant fusion protein comprising (a) an IL-9 or a biologically active fragment thereof; (b) a modified IL-9 receptor (IL-9R) comprising an IL- 9R extracellular domain, a transmembrane domain, and IL-9R intracellular domain, in which one or both of the IL-9R extracellular domain and IL-9R intracellular domain is a variant domain relative to the corresponding domain of wild-type IL-9R, such as relative to the corresponding domain in human IL-9R set forth in SEQ ID NO: 7; and (c) a linker (e.g., peptide linker) that joins or links the IL-9 or biologically active fragment thereof and the modified IL-9R. In some embodiments, the variant domain comprises one or more mutations relative to the respective domain of a wild-type IL-9R. In some embodiments, the one or more mutations is a deletion of a contiguous sequence of amino acids such that the contiguous sequence of amino acids is absent relative to the respective wild-type IL-9R. In some embodiments, the variant domain is a truncated domain that is deleted for or lacks a contiguous sequence of amino acids relative to the corresponding domain in human IL-9R set forth in SEQ ID NO: 7. In some embodiments, the intracellular IL-9R domain is capable of signaling through STAT1, STAT3, and / or STAT5 pathways.

[0209] Provided herein is a recombinant fusion protein comprising (a) an IL-9 or a biologically active fragment thereof; (b) a modified IL-9 receptor (IL-9R) comprising an IL- 9R extracellular domain, an IL-9R transmembrane domain, and a IL-9R intracellular domain, wherein one or both of the IL-9R extracellular domain and the IL-9R intracellular domain is a variant that is truncated relative to the domain of wild-type IL-9R; and (c) a linker (e.g., peptide linker), wherein the IL-9 is connected to the modified IL-9R via the peptide linker. In such embodiments, the intracellular IL-9R domain is capable of signaling through STAT1, STAT3, and / or STAT5 pathways.

[0210] In some embodiments, the IL-9R extracellular domain is a wild-type IL-9R extracellular domain and the IL-9R intracellular domain is a variant IL-9R intracellular domain, such as a mutated, e.g., truncated, IL-9R intracellular domain. In some embodiments, the IL-9R extracellular domain is a variant IL-9R extracellular domain, such as a truncatedIL-9R extracellular domain, and the IL-9R intracellular domain is a wild-type IL-9R intracellular domain. In some embodiments, the IL-9R extracellular domain is a variant IL- 9R extracellular domain, such as a truncated IL-9R extracellular domain, and the IL-9R intracellular domain is a variant IL-9R intracellular domain, such as a mutated, e.g., truncated, IL-9R intracellular domain. In some of any of the embodiments, the transmembrane domain is a IL-9R transmembrane domain, such as the wild-type IL-9R transmembrane domain. In other embodiments, the transmembrane domain is a heterologous transmembrane domain from another protein.

[0211] Provided herein is a recombinant fusion protein comprising: (a) an IL-9 or a biologically active fragment thereof; (b) a modified IL-9 receptor (IL-9R) comprising an IL- 9R extracellular domain, an IL-9R transmembrane domain, and a variant IL-9R intracellular domain comprising one or more mutations compared to the wild-type IL-9R intracellular domain, wherein the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways; and (c) peptide linker, wherein the IL-9 is connected to the modified IL-9R via the peptide linker.

[0212] Provided herein is a recombinant fusion protein comprising: (a) an IL-9 or a biologically active fragment thereof; (b) a modified IL-9 receptor (IL-9R) comprising a variant IL-9R extracellular domain comprising one or more mutations compared to the wildtype IL-9R extracellular domain, an IL-9R transmembrane domain, and an IL-9R intracellular domain, wherein the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways; and (c) peptide linker, wherein the IL-9 is connected to the modified IL-9R via the peptide linker. In some embodiments, the one or more mutations is a deletion of a contiguous sequence of amino acids such that the contiguous sequence of amino acids is absent relative to the respective wild-type IL-9R. In some embodiments, the variant domain is a truncated domain that is deleted for or lacks a contiguous sequence of amino acids relative to the corresponding domain in human IL-9R set forth in SEQ ID NO: 7.

[0213] Provided herein is a recombinant fusion protein comprising: (a) an IL-9 or a biologically active fragment thereof; (b) a modified IL-9 receptor (IL-9R) comprising a variant IL-9R extracellular domain comprising one or more mutations compared to the wildtype IL-9R extracellular domain, an IL-9R transmembrane domain, and a variant IL-9R intracellular domain comprising one or more mutations compared to the wild-type IL-9R intracellular domain, wherein the one or more mutations promote signaling through STAT1,STAT3, and / or STAT5 pathways; and (c) peptide linker, wherein the IL-9 is connected to the modified IL-9R via the peptide linker. In some embodiments, the one or more mutations are a deletion of a contiguous sequence of amino acids such that the contiguous sequence of amino acids is absent relative to the respective wild-type IL-9R. In some embodiments, the variant domain is a truncated domain that is deleted for or lacks a contiguous sequence of amino acids relative to the corresponding domain in human IL-9R set forth in SEQ ID NO: 7.

[0214] In some of any of the embodiments, the recombinant fusion protein is a constitutively active cytokine receptor that elicits signaling through STAT1, STAT3, or STAT5 pathway. In some embodiments, the recombinant fusion protein elicits signaling through STAT1 pathway. In some embodiments, the recombinant fusion protein elicits signaling through STAT3 pathway. In some embodiments, the recombinant fusion protein elicits signaling through STAT5 pathway. In some embodiments, the recombinant fusion protein elicits signaling through STAT1, STAT3, and STAT5 pathways at the same time. In some embodiments, the recombinant fusion protein elicits signaling through STAT1, STAT3, and STAT5 pathways sequentially in any order. In some embodiments, signaling can be demonstrated by sustained or prolonged STAT activation. In some embodiments, STAT activation can be shown by detecting phosphorylated STAT. In some embodiments, signaling through STAT1, STAT3, and / or STAT5 is determined by detecting phosphorylated STAT1, STAT3 and / or STAT5. In some embodiments, STAT1, STAT3, and / or STAT5 phosphorylation can be detected by Western blot or flow cytometry with antibodies that specifically bind to phosphorylated STAT1, STAT3, and / or STAT5. In some embodiments, signaling through STAT1, STAT3, and / or STAT5 can be determined by any method known in the art.

[0215] It is understood that reference to amino acids, including to a specific sequence set forth as a SEQ ID NO used to describe domain organization (e.g., of an extracellular domain, transmembrane domain, or intracellular domain) are for illustrative purposes and are not meant to limit the scope of the embodiments provided. It is understood that polypeptides and the description of domains thereof are theoretically derived based on homology analysis and alignments with similar molecules. Thus, the exact locus can vary, and is not necessarily the same for each protein. Hence, a specific domain can be several amino acids (such as one, two, three or four) longer or shorter. Typically, it will be understood that any transmembrane domain(s) identified for the polypeptides herein are identified pursuant to criteria routinelyemployed in the art for identifying that type of hydrophobic domain. The exact boundaries of a transmembrane domain may vary but most likely by no more than about 5 amino acids at either end of the domain as initially identified. In some embodiments, the extracellular domain, when it is free of the transmembrane and cytoplasmic domains, is one that may be soluble (i.e., is not membrane bound). It is understood that the intracellular signaling domain is a IL-9R sequence or a variant or portion thereof that exhibits ability to elicit intracellular signaling such as by recruiting STAT molecules (e.g., STAT1, STAT3, and STAT5).

[0216] In some embodiments, an advantage of the tethered receptors provided herein is that the receptors are constitutively active in the absence of exogenous or free IL-9 ligand. That is, downstream IL-9R signaling is constitutive in the absence of exogenous or free ligand binding to the extracellular domain (e.g., ECD) of the tethered receptor. In particular embodiments, the synthetic cytokine receptors provided herein elicit IL-9R signaling in the absence of free or exogenous IL-9.A. IL-9

[0217] In some embodiments, the recombinant fusion protein comprises an IL-9. In some embodiments, the IL-9 is tethered (or linked) to the IL-9R, such as via a linker, e.g., any linker as described in Section I.B.

[0218] In some embodiments, the IL-9 is a wild-type IL-9. In particular embodiments, the IL-9 is a human IL-9.

[0219] In some embodiments, the IL-9 is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 85% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 86% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 87% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 88% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 89% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 90% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 91% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 92% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 93% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 94% identical to theamino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 95% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 96% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 97% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 98% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is at least 99% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 is 100% identical to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the IL-9 has the amino acid sequence set forth in SEQ ID NO: 8.

[0220] In some embodiments, the IL-9 is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 85% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 86% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 87% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 88% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 89% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 90% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 91% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 92% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 93% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 94% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 95% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 96% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 97% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 98% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is at least 99% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 is 100% identical to the nucleic acid sequence of SEQ ID NO: 6. In some embodiments, the IL-9 has the nucleic acid sequence set forth in SEQ ID NO: 6. 1

[0221] In some embodiments, the IL-9 sequence is preceded by an N-terminal signal peptide sequence to control expression of the recombinant cytokine fusion receptor. In some embodiments, the signal peptide is native to IL-9. In some embodiments, the signal peptide is MLLAMVLTSALLLCSMAG (SEQ ID NO: 108). In some embodiments, the signal peptide is heterologous to IL-9.

[0222] In some embodiments, the IL-9 sequence of the fusion protein lacks the signal peptide sequence, which is typically cleaved when the fusion protein is expressed by the cell, such as for expression on the cell surface as a transmembrane receptor.

[0223] In some embodiments, the IL-9 is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 85% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 86% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 87% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 88% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL- 9 is at least 89% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 90% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 91% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 92% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 93% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 94% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 95% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 96% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 97% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 98% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is at least 99% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 is 100% identical to the amino acid sequence of SEQ ID NO: 185. In some embodiments, the IL-9 has the amino acid sequence set forth in SEQ ID NO: 185.B. Linker

[0224] In some embodiments, the recombinant fusion protein comprises a linker. In some embodiments, the linker tethers the IL-9 to the IL-9R. In some embodiments, the IL-9 is fused to the linker which is fused to the IL-9R, thereby making a tethered IL-9 / IL-9R protein. In some embodiments, the linker is a peptide linker. In some embodiments, the linker is a flexible linker. In some embodiments, the linker is a rigid linker. In some embodiments, the linker is a cleavable linker. In some embodiments, the IL-9 and IL-9R are directly linked to each other. In some embodiments, the different elements are linked via a peptide linker, such as a (GxS)n linker, wherein x can be an integer between 1 and 10, and n can be an integer between 2 and 20. In some embodiments, the linker is 5 to 30 amino acids in length. In some embodiments, the linker is 12 to 26 amino acids in length. In some embodiments, the linker is 15 to 20 amino acids in length.

[0225] In some embodiments, the linker is a GS linker. In some embodiments, the linker comprises the sequence GS, GGS, GGGGS (SEQ ID NO: 10), GGGGGS (SEQ ID NO: 11) or combinations thereof. In some embodiments, the linker comprises (GGS)n, wherein n is 1 to 10. In some embodiments, the linker comprises (GGGGS)n(SEQ ID NO: 12), wherein n is 1 to 6. In some embodiments, the linker comprises (GGGGGS)n(SEQ ID NO: 13), wherein n is 1 to 5.

[0226] In some embodiments, the linker is (GGGGS)s (SEQ ID NO: 15).

[0227] In some embodiments, the linker is (GGGGS)4 (SEQ ID NO: 107).

[0228] In some embodiments, the linker is (GGGGS)3 (SEQ ID NO: 14). In some embodiments, the linker is encoded by the nucleotide sequence set forth in SEQ ID NO: 3.

[0229] In some embodiments, the linker is (GGGGS (SEQ ID NO: 106). In particular, results herein demonstrate that fusion proteins with shorter linkers, as exemplified by (GGGGS)2 linker, between the IL-9 and IL-9R exhibit superior transfection efficiency and STAT signaling activity. In some embodiments, the linker is any flexible linker of 6 to 12 amino acids in length, such as 8 to 10 amino acids in length. In some embodiments, the linker is 10 amino acids in length.C. Extracellular Domain

[0230] In some embodiments, the recombinant fusion protein comprises an IL-9R that comprises an extracellular domain.

[0231] In some embodiments, the extracellular domain is an extracellular domain of a wild-type IL-9R. In some embodiments, the wild-type IL-9R comprises the sequence as set forth in SEQ ID NO: 7. In some embodiments, the wild-type IL-9R comprises the nucleic sequence as set forth in SEQ ID NO: 1. In some embodiments, the extracellular domain of the wild-type IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 86% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 87% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 88% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 89% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 91% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 92% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 93% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 94% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 96% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 97% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 98% identical to the amino acid sequence ofSEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 99% identical to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the extracellular domain comprises an amino acid sequence that is identical to the amino acid sequence of SEQ ID NO: 54.

[0232] In some embodiments, the extracellular domain is a variant IL-9R extracellular domain that is truncated relative to the wild-type IL-9R extracellular domain. In some embodiments, the extracellular domain is at least about 130 amino acids in length. In some embodiments, the extracellular domain is at most about 230 amino acids in length. In some embodiments, the IL-9R extracellular domain is less than the full length extracellular domain of wildtype human IL-9R, such as is less than the full length sequence set forth in SEQ ID NO: 54. In some embodiments, the extracellular domain is about 130 amino acids in length, 135 amino acids in length, 140 amino acids in length, 145 amino acids in length, 145 amino acids in length, 150 amino acids in length, 155 amino acids in length, 160 amino acids in length, 165 amino acids in length, 170 amino acids in length, 175 amino acids in length, 180 amino acids in length, 185 amino acids in length, 190 amino acids in length, 195 amino acids in length, 200 amino acids in length, 205 amino acids in length, 210 amino acids in length, 215 amino acids in length, 220 amino acids in length, or has a length that is a value between any of the foregoing.

[0233] In some embodiments, the variant IL-9R extracellular domain is truncated in which a contiguous sequence of amino acids is deleted from the N-terminus of wild-type IL- 9R extracellular domain, such as relative to SEQ ID NO:54. In some embodiments, the variant IL-9R extracellular domain is a truncated IL-9R that lacks a contiguous sequence of amino acids at the N-terminus relative to wild-type IL-9R extracellular domain, such as relative to SEQ ID NO: 54.

[0234] In some embodiments, the variant IL-9R extracellular domain lacks up to 115 contiguous amino acids from the N-terminus relative to wild-type IL-9R extracellular domain set forth in SEQ ID NO: 54. In some embodiments, the variant IL-9R extracellular domain lacks 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110 or 115 contiguous amino acids, or a number of contiguous amino acids between any of the foregoing, from the N-terminus relative to wild-type IL-9R extracellular domain set forth in SEQ ID NO: 54. In some embodiments, the variant IL-9R extracellular domain lacks between 20-108 contiguous amino acids from the N-terminus relative to wild-type IL-9R extracellulardomain set forth in SEQ ID NO: 54. In some embodiments, the variant IL-9R extracellular domain lacks between 70-99 contiguous amino acids from the N-terminus relative to wildtype IL-9R extracellular domain set forth in SEQ ID NO: 54.

[0235] In some of any of the provided embodiments, the variant IL-9R extracellular domain comprises the fibronectin-type III domain corresponding to amino acids 109-219 of SEQ ID NO: 54. The fibronectin-type III domain is a protein structural motif of a repeating structural unit with a characteristic fold composed of several beta sheets found in both IL-9 and the IL-9R that plays a role in the interaction between the two proteins for signal transduction. In particular, the presence of the domain is believed to promote high affinity binding between IL-9 and IL-9R.

[0236] In some embodiments, the variant IL-9R extracellular domain lacks a contiguous sequence of amino acids 1-99 corresponding to numbering of SEQ ID NO: 54.

[0237] In some embodiments, the extracellular domain of the mutated IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 86% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 87% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 88% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 89% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 91% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 92% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 93% identical to the amino acid sequence ofSEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 94% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 96% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 97% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 98% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is at least 99% identical to the amino acid sequence of SEQ ID NO: 105. In some embodiments, the extracellular domain comprises an amino acid sequence that is identical to the amino acid sequence of SEQ ID NO: 105.

[0238] In some embodiments, the extracellular domain of the mutated IL-9R comprises the nucleic acid sequence set forth in SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 85% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 86% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 87% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 88% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 89% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 90% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 91% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 92% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellulardomain comprises a nucleic acid sequence that is at least 93% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 94% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 95% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 96% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 97% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 98% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is at least 99% identical to the nucleic acid sequence of SEQ ID NO: 104. In some embodiments, the extracellular domain comprises a nucleic acid sequence that is identical to the nucleic acid sequence of SEQ ID NO: 104.D. Transmembrane domain

[0239] In some embodiments, the recombinant fusion protein comprises an IL-9R that comprises a transmembrane domain. In some embodiments, the transmembrane domain is a transmembrane domain of a wild-type IL-9R. In some embodiments, the wild-type IL-9R comprises the sequence as set forth in SEQ ID NO: 7.

[0240] In some embodiments, the transmembrane domain of the wild-type IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 75% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 86% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 87% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domaincomprises an amino acid sequence that is at least 88% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 89% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 91% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 92% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 93% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 94% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 96% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 97% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 98% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is at least 99% identical to the amino acid sequence of SEQ ID NO: 55. In some embodiments, the transmembrane domain comprises an amino acid sequence that is identical to the amino acid sequence of SEQ ID NO: 55.E. Intracellular Domain (ICD)

[0241] In some embodiments, the recombinant fusion protein comprises an IL-9R intracellular domain. In some embodiments, the intracellular domain is capable of interleukin 9 receptor (IL-9R) signaling. In some embodiments, the intracellular domain capable of IL- 9R signaling comprises an intracellular domain of IL-9R. In some embodiments, the IL-9R intracellular domain comprises a naturally occurring IL-9R (i.e., wild-type IL-9R). In some embodiments, the IL-9R intracellular domain comprises a mammalian IL-9R. In some embodiments, the IL-9R intracellular domain comprises a human IL-9R. In some embodiments, the IL-9R intracellular domain comprises a wild-type human IL-9R.

[0242] In some embodiments, the intracellular domain is an intracellular domain of a wild-type IL-9R. In some embodiments, the wild-type IL-9R comprises the sequence as set forth in SEQ ID NO: 7. In some embodiments, the intracellular domain of the wild-type IL- 9R comprises the amino acid sequence set forth in SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 86% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 87% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 88% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 89% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 91% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 92% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 93% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 94% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 95% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 96% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 97% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least 98% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is at least99% identical to the amino acid sequence of SEQ ID NO: 56. In some embodiments, the intracellular domain comprises an amino acid sequence that is identical to the amino acid sequence of SEQ ID NO: 56.

[0243] In some embodiments, the IL-9R intracellular domain is a variant intracellular domain. In some embodiments, the variant intracellular domain comprises mutations compared to a wild-type IL-9R intracellular domain. In some embodiments, the IL-9R intracellular domain is a domain that is capable of mediating IL-9R signaling, such as through STAT1, STAT3, and / or STAT5 pathways.

[0244] In some embodiments, the intracellular domain is at least about 150 amino acids in length. In some embodiments, the intracellular domain is at most about 250 amino acids in length. In some embodiments, the intracellular domain is about 150 amino acids to about 250 amino acids in length. In some embodiments, the intracellular domain is about 169, 220, 223, or 230 amino acids in length. In some embodiments, the intracellular domain is about 169 amino acids in length. In some embodiments, the intracellular domain is about 220 amino acids in length. In some embodiments, the intracellular domain is about 223 amino acids in length. In some embodiments, the intracellular domain is about 230 amino acids in length. In some embodiments, the intracellular domain is 169 amino acids in length. In some embodiments, the intracellular domain is 220 amino acids in length. In some embodiments, the intracellular domain is 223 amino acids in length. In some embodiments, the intracellular domain is 230 amino acids in length.

[0245] In some embodiments, the variant IL-9R intracellular domain is a variant of a wild-type IL-9R intracellular domain and comprises one or more mutations compared to the wild-type IL-9R intracellular domain. In some embodiments, the variant IL-9R intracellular domain is a variant of a wild-type IL-9R intracellular domain and comprises one or more mutations compared to the wild-type IL-9R intracellular domain set forth in SEQ ID NO: 56. In some embodiments, the one or more mutations comprises one or more amino acid insertions, deletions, and / or substitutions. In some embodiments, the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways.

[0246] In some embodiments, the IL-9R intracellular domain is 230 amino acids in length. In some embodiments, the wild-type IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about98%, or about 99% identical to SEQ ID NO: 56. In some embodiments, the wild-type IL-9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 56. In some embodiments, the wild-type IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 56.

[0247] In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 8. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprisesa sequence of amino acids that is at least about 99% identical to SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 56. In some embodiments, the IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 56.

[0248] In some embodiments, the intracellular domain is a variant IL-9R intracellular domain capable of interleukin 9 receptor (IL-9R) signaling. In some embodiments, the variant IL-9R intracellular domain comprises one or more mutations compared to a naturally occurring IL-9R. The one or more mutation(s) may be a substitution, insertion, deletion, or combination thereof. In some embodiments, the one or more mutation(s) promote downstream signaling via a STAT. Methods of determining whether a particular mutation will trigger the downstream signaling is known to a skilled artisan (e.g., assaying for STAT1, STAT3, or STAT5 phosphorylation following growth of the cells harboring the receptor being tested in the absence of growth factors). In some embodiments, the variant IL-9R intracellular domain elicits signaling through STAT1, STAT3, and / or STAT5 pathways. In some embodiments, the variant IL-9R intracellular domain promotes signaling through STAT1, STAT3, and / or STAT5 pathways.

[0249] In some embodiments, the one or more mutations may be an insertion, deletion or substitution of amino acids as compared to the wild-type human IL-9 intracellular domain (e.g., as compared to SEQ ID NO: 56). Various non-limiting mutations of variant intracellular domains are described herein. Exemplary variant IL-9 intracellular domains include those described by their reference SEQ ID NO as outlined in Table 1 below.Table 1

[0250] In some embodiments, STAT1 signaling by variant IL-9R is increased compared to STAT1 signaling by wild-type IL-9R. In some embodiments, STAT3 signaling by variant IL-9R is increased compared to STAT3 signaling by wild-type IL-9R. In some embodiments, STAT5 signaling by variant IL-9R is increased compared to STAT5 signaling by wild-type IL-9R. In some embodiments, signaling through the STAT1, STAT3, and / or STAT5 pathways is sustained for a longer period of time compared to STAT1, STAT3, and / or STAT5 via wild-type IL-9R. In some embodiments, the period of time is about 6 hours, 12hours, 24 hours, 36 hours, 48 hours, 72 hours, or longer. In some embodiments, the period of time is about 24 hours. In some embodiments, signaling through STAT1, STAT3, and / or STAT5 is sustained for as long as the cell expresses any of the recombinant fusion proteins provided herein. In some embodiments, sustained STAT1, STAT3, and / or STAT5 signaling is determined by phosphorylation status of STAT1, STAT3, and / or STAT5.

[0251] In some embodiments, the variant IL-9R intracellular domain is a variant of a wild-type IL-9R intracellular domain and comprises one or more mutations compared to the wild-type IL-9R intracellular domain. In some embodiments, the variant IL-9R intracellular domain is a variant of a wild-type IL-9R intracellular domain and comprises one or more mutations compared to the wild-type IL-9R intracellular domain set forth in SEQ ID NO: 56. In some embodiments, the one or more mutations comprises one or more amino acid insertions, deletions, and / or substitutions. In some embodiments, the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways.

[0252] In some embodiments, the mutation is a deletion and the variant is a deleted IL-9R intracellular signaling domain lacking one or more regions of the wild-type IL-9R intracellular signaling domain (e.g., lacking one or more regions of the sequence set forth in SEQ ID NO:56). In some embodiments, the IL-9R lacks up to 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75 or 80 contiguous amino acids present within a wild-type IL-9R intracellular domain (e.g., SEQ ID NO: 56). In some embodiments, the IL-9R lacks a region of 10 contiguous amino acids with reference to a wild-type IL-9R intracellular domain. In some embodiments, the region that is deleted is a sequence that is not necessary for functional activity of the IL-9R intracellular domain such that IL-9R-mediated signaling is retained.

[0253] In some embodiments, the variant is a truncated IL-9R intracellular signaling domain that is truncated by deletion of one or more amino acid residues at one or both of the N- and C-terminus of a wild-type IL-9R intracellular domain. In some embodiments, the truncated IL-9R is a contiguous sequence of amino acids of at least 150 amino acids in length from the wild-type IL-9R intracellular signaling domain set forth in SEQ ID NO: 56 that is truncated by deletion of one or more amino acid residues at one or both of the N- and C- terminus of SEQ ID NO: 56. In some embodiments, the truncated IL-9R signaling domain is a contiguous sequence of from 150 amino acids to 229 amino acids of the sequence set forth in SEQ ID NO: 56. In some embodiments, the variant IL-9R is an N-terminal truncation of upto 80 amino acids. In some embodiments, the variant IL-9R is an N-terminal truncation of up to 70 amino acids. In some embodiments, the variant IL-9R is an N-terminal truncation of up to 80 amino acids. In some embodiments, the variant IL-9R is an N-terminal truncation of up to 50 amino acids. In some embodiments, the variant IL-9R is an N-terminal truncation of up to 40 amino acids. In some embodiments, the variant IL-9R is an N-terminal truncation of up to 30 amino acids. In some embodiments, the variant IL-9R is an N-terminal truncation of up to 20 amino acids. In some embodiments, the variant IL-9R is an N-terminal truncation of up to 10 amino acids. In some embodiments, the variant IL-9R is an N-terminal truncation of up to 7 amino acids. In some embodiments, the variant IL-9R is an N-terminal truncation of up to 5 amino acids. In some embodiments, one or more additional mutation can be present in any of such truncated IL-9R intracellular domain.

[0254] In some embodiments, the mutation is a deletion and the variant is a truncated IL- 9R intracellular signaling domain that is truncated by deletion of one or more amino acid residues at one or both of the N- and C-terminus of a wild-type IL-9R intracellular domain. In some embodiments, the truncated IL-9R is a contiguous sequence of amino acids of at least 150 amino acids in length from the wild-type IL-9R intracellular signaling domain set forth in SEQ ID NO: 8 that is truncated by deletion of one or more amino acid residues at one or both of the N- and C-terminus of SEQ ID NO: 8. In some embodiments, the truncated IL-9R signaling domain is a contiguous sequence of from 150 amino acids to 229 amino acids of the sequence set forth in SEQ ID NO: 8. In some embodiments, the variant IL-9R is an N- terminal truncation of up to 80 amino acids. In some embodiments, the variant IL-9R is an N- terminal truncation of up to 70 amino acids. In some embodiments, the variant IL-9R is an N- terminal truncation of up to 80 amino acids. In some embodiments, the variant IL-9R is an N- terminal truncation of up to 50 amino acids. In some embodiments, the variant IL-9R is an N- terminal truncation of up to 40 amino acids. In some embodiments, the variant IL-9R is an N- terminal truncation of up to 30 amino acids. In some embodiments, the variant IL-9R is an N- terminal truncation of up to 20 amino acids. In some embodiments, the variant IL-9R is an N- terminal truncation of up to 10 amino acids. In some embodiments, the variant IL-9R is an N- terminal truncation of up to 7 amino acids. In some embodiments, the variant IL-9R is an N- terminal truncation of up to 5 amino acids. In some embodiments, one or more additional mutation can be present in any of such truncated IL-9R intracellular domain.

[0255] In some embodiments, the variant IL-9R intracellular domain comprises a deletion, wherein the variant IL-9R lacks a contiguous sequence of amino acids between the N-terminus and C-terminus of wild-type IL-9R intracellular domain. In some embodiments, the variant IL-9R intracellular domain comprises a deletion, wherein the variant IL-9R lacks a noncontiguous sequence of amino acids between the N-terminus and C-terminus of wildtype IL-9R intracellular domain. In some embodiments, the deletion is a truncation. In some embodiments, the intracellular domain is a truncated IL-9R intracellular domain and the deletion is a truncation that deletes a contiguous sequence of amino acids from the C- terminus of wild-type IL-9R intracellular domain. In some embodiments, the variant IL-9R intracellular domain is a truncated IL-9R that lacks a contiguous sequence of amino acids at the C-terminus of wild-type IL-9R intracellular domain. In some embodiments, the truncated IL-9R intracellular domain is truncated by between 62 and 99 contiguous amino acids from the C-terminus of wild-type IL-9R intracellular domain. In some embodiments, the variant IL-9R intracellular domain is a truncated IL-9R that lacks a contiguous sequence of amino acids at the C-terminus of wild-type IL-9R intracellular domain. In some embodiments, the variant IL-9R intracellular domain comprises a deletion, wherein the variant IL-9R lacks a contiguous sequence of amino acids at the N-terminus of wild-type IL-9R intracellular domain. In some embodiments, the variant IL-9R intracellular domain is a truncated IL-9R that lacks a noncontiguous sequence of amino acids at the C-terminus of wild-type IL-9R intracellular domain. In some embodiments, the variant IL-9R intracellular domain comprises a deletion, wherein the variant IL-9R lacks a noncontiguous sequence of amino acids at the N-terminus of wild-type IL-9R intracellular domain. In some of any of such embodiments, the truncation is at the C-terminus of wild-type IL-9R intracellular domain set forth in SEQ ID NO: 56. In some of any of such embodiments, the deletion is at the N-terminus of wildtype IL-9R intracellular domain set forth in SEQ ID NO: 56.

[0256] In some embodiments, the variant IL-9R intracellular domain comprises a deletion which causes it to have fewer amino acids than a wild-type IL-9R intracellular domain. In some embodiments, the variant IL-9R intracellular domain is less than 260 amino acids in length. In some embodiments, the variant IL-9R intracellular domain is about 100 to 260 amino acids in length. In some embodiments, the variant IL-9R intracellular domain comprises a BOX1 motif and / or a BOX2 motif. In some embodiments, the variant IL-9R intracellular domain comprises a BOX1 motif. In some embodiments, the variant IL-9Rintracellular domain comprises a BOX2 motif. In some embodiments, the variant IL-9R is 230 amino acids in length.

[0257] In some embodiments, the truncated IL-9R intracellular domain or variant thereof is truncated by between 62 and 99 contiguous amino acids from the C-terminus of wild-type IL-9R intracellular domain. In some embodiments, the truncated IL-9R intracellular domain or variant thereof is truncated by 61 contiguous amino acids from the C-terminus of wild-type IL-9R intracellular domain. In some embodiments, the truncated IL-9R intracellular domain or variant thereof is truncated by 62 contiguous amino acids from the C-terminus of wild-type IL-9R intracellular domain. In some embodiments, the truncated IL-9R intracellular domain or variant thereof is truncated by 99 contiguous amino acids from the C-terminus of wild-type IL-9R intracellular domain.

[0258] In some embodiments, the variant IL-9R intracellular domain comprises a deletion, wherein the variant IL-9R lacks amino acids 132 to 230 of SEQ ID NO: 56. In some embodiments, the variant IL-9R intracellular domain comprises a deletion, wherein the variant IL-9R lacks amino acids 134 to 230 of SEQ ID NO: 56.

[0259] In some embodiments, the variant IL-9R intracellular domain comprises an insertion. In some embodiments, variant IL-9R intracellular domain comprises an insertion, wherein the variant IL-9R intracellular domain comprises additional amino acids compared to a wild-type IL-9R. In some embodiments, the insertion comprises adding between 1-20 amino acids compared to a wild-type IL-9R intracellular domain. In some embodiments, the insertion comprises adding between 1-20 contiguous amino acids compared to a wild-type IL-9R intracellular domain.

[0260] In some embodiments, the IL-9R intracellular domain comprises one or more amino acid deletions and insertions. In some embodiments, the IL-9R intracellular domain comprises deletion of a contiguous sequence of amino acids and insertion of a contiguous sequence of amino acids. In some embodiments, the length of the deleted contiguous sequence of amino acids and length of the inserted contiguous sequence of amino acids are the same. In some embodiments, the length of the deleted contiguous sequence of amino acids and length of the inserted contiguous sequence of amino acids are the different.

[0261] In some embodiments, the IL-9R intracellular domain comprises deletions of a region such as those outlined in Table 2. In some embodiments, the IL-9R intracellular domain comprises deletions of contiguous amino acids compared to wild-type IL-9Rintracellular domain. In some embodiments, the IL-9R intracellular domain comprises a deletion of a region, such as those outlined in Table 2, at the C terminus of wild-type IL-9R intracellular domain. In some embodiments, the IL-9R intracellular domain comprises a deletion of a region at the N terminus of wild-type IL-9R intracellular domain. In some embodiments, the IL-9R intracellular domain comprises a deletion of a region of contiguous amino acids within the wild-type IL-9R intracellular domain. In some embodiments, the IL- 9R intracellular domain comprises deletions of non-contiguous amino acids compared to the wild-type IL-9R intracellular domain. In some embodiments, the IL-9R intracellular domain comprises deletions of a plurality of regions, such as those outlined in Table 2, of the wildtype IL-9R intracellular domain. Exemplary deleted regions from IL-9R intracellular domain are shown in Table 2. In some embodiments, the IL-9R intracellular domain is deleted for contiguous amino acids within or including contiguous amino acids 29-38, 39-48, 69-78 or 154-163, with reference to numbering of amino acids in SEQ ID NO: 56.Table 2: Exemplary Deletion Mutations

[0262] In some embodiments, the IL-9R intracellular domain comprises deletions of a plurality of regions, of the wildtype IL-9R intracellular domain. Exemplary intracellular domains with a plurality of deleted regions from IL-9R intracellular domain are shown in Table 3.Table 3: Exemplary Deletions of Multiple Regions

[0263] In some embodiments, the variant IL-9R intracellular domain comprises a substitution. In some embodiments, the substitution comprises replacing one or more amino acids with one or more different amino acids. In some embodiments, the variant IL-9R intracellular domain comprises one or more substitutions. In some embodiments, the variantIL-9R intracellular domain comprises one or more substitutions compared to a wild-type IL- 9R intracellular domain. In some embodiments, the variant IL-9R intracellular domain comprises one or more substitutions compared to a wild-type IL-9R intracellular domain as set forth in SEQ ID NO: 56.

[0264] In some embodiments, the IL-9R intracellular domain comprises replacement of a contiguous sequence of amino acids with one or more STAT binding domains. In some embodiments, the contiguous sequence of amino acids is replaced with one STAT binding domain. In some embodiments, the STAT binding domain is derived from a Type I cytokine receptor. In some embodiments, the Type I cytokine receptor is selected from the group consisting of interleukin 2 receptor (IL-2R), interleukin 4 receptor (IL-4R), interleukin 7 receptor (IL-7R), interleukin 13 receptor (IL-13R), interleukin 15 receptor (IL-15R), and interleukin 2 receptor (IL-21R). In some embodiments, the Type I cytokine receptor is IL-2R.

[0265] In some embodiments, the contiguous sequence of amino acids is replaced with one or more STAT binding domains. In some embodiments, the contiguous sequence of amino acids is replaced with one STAT binding domain. In some embodiments, the contiguous sequence of amino acids is replaced with two STAT binding domains. In some embodiments, the contiguous sequence of amino acids is replaced with three STAT binding domains. In some embodiments, replacement of the contiguous sequence of amino acids with one, two, or three STAT binding domains increases STAT binding and signaling.

[0266] In some embodiments, the wild-type IL-9R intracellular domain comprises a STAT binding domain. In some embodiments, the variant IL-9R intracellular domain comprises a substitution of one or more amino acids in the STAT binding domain compared to a wild-type IL-9R intracellular domain. In some embodiments, the amino STAT binding domain of a wild-type IL-9R comprises the sequence of amino acids set forth in SEQ ID NO: 93. In some embodiments, the STAT binding domain of the variant IL-9R intracellular domain differs from SEQ ID NO: 93 by 1, 2, or 3 amino acids. In some embodiments, the STAT binding domain of the variant IL-9R intracellular domain differs from SEQ ID NO: 93 by 1 amino acid. In some embodiments, the STAT binding domain of the variant IL-9R intracellular domain differs from SEQ ID NO: 93 by 2 amino acids. In some embodiments, the STAT binding domain of the variant IL-9R intracellular domain differs from SEQ ID NO: 93 by 3 amino acids. In some embodiments, the insertion in the variant IL-9R intracellular domain occurs after the 108thamino acid of the wild-type IL-9R as set forth in SEQ ID NO:56. Exemplary variant tethered IL-9R intracellular domains comprising substitutions are shown in Table 4.Table 4: Exemplary Substitution Mutations

[0267] In some embodiments, the one or more STAT binding domains comprises YLPQ (SEQ ID NO: 93). In some embodiments, the one or more STAT binding domains comprises YRPQ (SEQ ID NO: 94). In some embodiments, the one or more STAT binding domains comprises YLPL (SEQ ID NO: 95). In some embodiments, the one or more STAT binding domain comprises YLKQ (SEQ ID NO: 96). In some embodiments, the one or more STAT binding domain comprises FLPQ (SEQ ID NO: 97).

[0268] In some embodiments, the STAT binding domain comprises a STAT1 binding domain. In some embodiments, the STAT binding domain comprises a STAT3 binding domain. In some embodiments, the STAT binding domain comprises a STAT5 binding domain.

[0269] In some embodiment, the variant IL-9R intracellular domain comprises an insertion of a STAT binding domain. In some embodiments, the variant IL-9R intracellular domain comprises an insertion of a STAT1, STAT3, and / or STAT5 binding domain. In some embodiments, the variant IL-9R intracellular domain comprises an insertion of a STAT1, STAT3, and STAT5 binding domain. In some embodiments, the variant IL-9R intracellular domain comprises an insertion of a STAT1, STAT3, or STAT5 binding domain.

[0270] In some embodiments, the STAT5 binding domain is 11 amino acids in length. In some embodiments, the STAT5 binding domain comprises amino acid sequence LNTDAYLSLQE (SEQ ID NO: 100). In some embodiments, the contiguous sequence of amino acids comprises 11 amino acid residues. In some embodiments, the contiguous sequence of amino acids comprises SNNNNYCALGC (SEQ ID NO: 101).

[0271] In some embodiments, the variant IL-9R intracellular domain comprises an insertion of a STAT5 binding domain. In some embodiments, the variant IL-9R intracellulardomain comprises an insertion of a STAT5 binding domain as set forth in SEQ ID NO: 100. In some embodiments, the variant IL-9R intracellular domain comprises an insertion of one or more STAT5 binding domains. In some embodiments, the variant IL-9R intracellular domain comprises an insertion of between 1 to 5 STAT5 binding domains. In some embodiments, the variant IL-9R intracellular domain comprises an insertion of between 1 to 3 STAT5 binding domains. In some embodiments, the variant IL-9R intracellular domain comprises an insertion of one STAT5 binding domain. In some embodiments, the variant IL- 9R intracellular domain comprises an insertion of between two STAT5 binding domains. In some embodiments, the variant IL-9R intracellular domain comprises an insertion of between three STAT5 binding domains. In some embodiments, the variant IL-9R intracellular domain comprises an insertion of between four STAT5 binding domains. In some embodiments, the variant IL-9R intracellular domain comprises an insertion of between five STAT5 binding domains. In some embodiments, the insertion of the one or more STAT5 binding domains replaces the sequence of amino acids set forth in SEQ ID NO: 101. Exemplary insertions are shown in Table 5.Table 5: Exemplary Insertion Mutations

[0272] In some embodiments, the variant IL-9R intracellular domain comprises one or more YLPQ, YRPQ, YLPL, FLPQ, or YLKQ STAT binding domains. In some embodiments, the variant IL-9R intracellular domain comprises two or more YLPQ, YRPQ, YLPL, FLPQ, or YLKQ STAT binding domains. In some embodiments, the variant IL-9R intracellular domain comprises three or more YLPQ, YRPQ, YLPL, FLPQ, or YLKQ STAT binding domains. In some embodiments, the variant IL-9R intracellular domain comprises four or more YLPQ, YRPQ, YLPL, FLPQ, or YLKQ STAT binding domains. In some embodiments, the variant IL-9R intracellular domain comprises five or more YLPQ, YRPQ, YLPL, FLPQ, or YLKQ STAT binding domains.

[0273] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 51. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 51. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 51.

[0274] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 52. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 52. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 52.

[0275] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 53. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 53. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 53.

[0276] In some embodiments, the IL-9R intracellular domain or variant thereof comprises one or more amino acid substitutions with reference to wild-type IL-9R intracellular domain (SEQ ID NO: 56). In some embodiments, the IL9R intracellular domain comprises a STAT binding motif. In some embodiments, the one or more amino acid substitutions are located in the STAT binding motif of the IL-9R intracellular domain. In some embodiments, the STAT binding motif comprises a STAT1, STAT3, and / or STAT5 binding motif.

[0277] In some embodiments, the STAT binding motif comprises YLPQ (SEQ ID NO: 93). In some embodiments, the STAT binding motif comprises a variant STAT binding motif. In some embodiments, the amino acid substitution comprises substitution of a leucine residue for an arginine residue with reference to SEQ ID NO: 93. In some embodiments, the amino acid substitution comprises substitution of a glutamine residue for a leucine residue withreference to SEQ ID NO: 93. In some embodiments, the amino acid substitution comprises substitution of a proline with a lysine with reference to SEQ ID NO: 93. In some embodiments, the STAT binding motif comprises YRPQ (SEQ ID NO: 94). In some embodiments, the STAT binding motif comprises YLPL (SEQ ID NO: 95). In some embodiments, the STAT binding motif comprises YLKQ (SEQ ID NO: 96). In some embodiments, the STAT binding motif comprises FLPQ (SEQ ID NO: 97).

[0278] In some embodiments, STAT1, STAT3, and / or STAT5 bind YLPQ. In some embodiments, STAT1, STAT3, and STAT5 bind YLPQ. In some embodiments, STAT1 and / or STAT3 bind YRPQ. In some embodiments, STAT1 and STAT3 bind YRPQ. In some embodiments, STAT5 binds YLPL. In some embodiments, STAT1, STAT3, and / or STAT5 bind YLKQ. In some embodiments, STAT1, STAT3, and STAT5 bind YLKQ.

[0279] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 47. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 47. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 47.

[0280] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 48. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 48. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 48.

[0281] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 49. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 49. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 49.

[0282] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 50. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 50. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 50.

[0283] In some embodiments, the variant IL-9R intracellular domain comprises one or more amino acid deletions with reference to a wild-type IL-9R intracellular domain and one or more amino acid substitutions with reference to a wild-type IL-9R intracellular domain. In some embodiments, the variant IL-9R intracellular domain comprises one or more amino acid deletions with reference to a wild-type IL-9R intracellular domain and one or more amino acid insertions with reference to a wild-type IL-9R intracellular domain.

[0284] In particular embodiments, the variant IL-9R comprises IL9R(Large D2) (SEQ ID NO: 43), IL9R(Large D2’) (SEQ ID NO: 44) or IL9R(dl5) (SEQ ID NO: 32) and one or amino acid substitutions as represented by IL9R(Mut6YRPQ) (SEQ ID NO: 47), IL9R(Mut7YLPL) (SEQ ID NO: 48), or IL9R(Mut9YLKQ) (SEQ ID NO: 49).

[0285] In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprisesa sequence of amino acids that is at least about 89% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 43. In some embodiments, the IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 43.

[0286] In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence ofamino acids that is at least about 87% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 44. In some embodiments, the IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 44.

[0287] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 18. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 18. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 18.

[0288] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 19. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 19. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 19.

[0289] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 20. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 20. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 20.

[0290] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 20. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 20. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 20.

[0291] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 21. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 21. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 21.

[0292] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 22. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 22. Insome embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 22.

[0293] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 23. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 23. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 23.

[0294] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 24. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 24. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 24.

[0295] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 25. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 25. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 25.

[0296] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 26. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 26. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 26.

[0297] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 27. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 27. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 27.

[0298] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 28. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 28. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 28.

[0299] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 29. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 29. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 29.

[0300] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 30. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 30. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 30.

[0301] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 31. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 31. Insome embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 31.

[0302] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 32. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 32. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 32.

[0303] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 33. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 33. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 33.

[0304] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 34. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 34. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 34.

[0305] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 35. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 35. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 35.

[0306] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 36. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 36. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 36.

[0307] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 37. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 37. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 37.

[0308] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 38. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 38. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 38.

[0309] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 39. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 39. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 39.

[0310] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 40. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 40. Insome embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 40.

[0311] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 41. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 41. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 41.

[0312] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 42. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 42. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 42.

[0313] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 45. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 45. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 45.

[0314] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 46. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 46. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 46.

[0315] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 47. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 47. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 47.

[0316] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 48. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 48. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 48.

[0317] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 49. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 49. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 49.

[0318] In some embodiments, the variant IL-9R intracellular domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 50. In some embodiments, the variant IL- 9R intracellular domain comprises the amino acid sequence set forth in SEQ ID NO: 50. In some embodiments, the variant IL-9R intracellular domain consists of the amino acid sequence set forth in SEQ ID NO: 50.F. Exemplary Tethered IL9 / IL9R Cytokine Receptors

[0319] Among provided recombinant fusion proteins are tethered IL9 / IL9R comprising IL-9, a peptide linker, and a modified IL-9R. In some embodiments, the IL-9 is set forth in SEQ ID NO: 185 (or SEQ ID NO: 8 with the signal peptide). In some embodiments, the peptide linker is (GGGGS)2(SEQ ID NO: 106), (GGGGS)3(SEQ ID NO: 14), or (GGGGS)4(SEQ ID NO: 107). In particular embodiments, the peptide linker is (GGGGS (SEQ ID NO: 106).

[0320] In particular embodiments, the modified IL-9R comprises a variant IL9R intracellular domain selected from IL9R(Large D2) (SEQ ID NO: 43), IL9R(Large D2’) (SEQ ID NO: 44) or IL9R(dl5) (SEQ ID NO: 32) and one or amino acid substitutions as represented by IL9R(Mut6YRPQ) (SEQ ID NO: 47), IL9R(Mut7YLPL) (SEQ ID NO: 48), or IL9R(Mut9YLKQ) (SEQ ID NO: 49). In particular embodiments, the variant IL9R intracellular domain is set forth in SEQ ID NO: 44.

[0321] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to any one of SEQ ID NOs: 58-92. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises the amino acid sequence set forth in any one of SEQ ID NOs: 58-92. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in any one of SEQ ID NOs: 58-92.

[0322] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to any one of SEQ ID NOs: 109-145. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises the amino acid sequence set forth in any one of SEQ ID NOs: 109-145. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in any one of SEQ ID NOs: 109-145.

[0323] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to any one of SEQ ID NOs: 57, 60, 66, 67, 69, 71-75, 77, 80, 81, 82, 83, 84. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises the amino acid sequence set forth in any one of SEQ ID NOs: 57, 60, 66, 67, 69, 71-75, 77, 80, 81, 82, 83, 84. In some embodiments, the tethered IL-9 / IL-9Rrecombinant fusion protein consists of the amino acid sequence set forth in any one of SEQ ID NOs: 57, 60, 66, 67, 69, 71-75, 77, 80, 81, 82, 83, 84.

[0324] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 158. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises the amino acid sequence set forth in SEQ ID NO: 158. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein consists of the amino acid sequence set forth in SEQ ID NO: 158.

[0325] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 9. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises the amino acid sequence set forth in SEQ ID NO: 9. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein consists of the amino acid sequence set forth in SEQ ID NO: 9. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 2. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises the amino acid sequence set forth in SEQ ID NO: 2. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein consists of the amino acid sequence set forth in SEQ ID NO: 2.

[0326] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein is preceded by an N-terminal signal peptide sequence to control expression of the recombinant cytokine fusion receptor. In some embodiments, the signal peptide is native to IL-9. In some embodiments, the signal peptide is MLLAMVLTSALLLCSMAG (SEQ ID NO: 108). In some embodiments, the signal peptide is heterologous to IL-9.

[0327] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein lacks the signal peptide sequence, which is typically cleaved when the fusion protein is expressed by the cell, such as for expression on the cell surface as a transmembrane receptor.

[0328] In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%,92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL- 9R comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 82 or 135. In some embodiments, the IL tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL- 9R comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 82 or 135. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 99% identical to SEQ IDNO: 82 or 135. In some embodiments, the tethered IL-9 / IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 82 . In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 82. In some embodiments, the tethered IL-9 / IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 135 . In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 135.

[0329] In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL- 9R comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 83 or 136. In some embodiments, the IL tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL- 9R comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 83 or 136. In some embodiments, thetethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 83 or 136. In some embodiments, the tethered IL-9 / IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 83. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 83. In some embodiments, the tethered IL-9 / IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 136. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 136.

[0330] In particular embodiments, the modified IL-9R comprises a variant IL9R extracellular domain set forth by the sequence set forth in SEQ ID NO: 105. In such embodiments, the modified IL-9R comprises a wild-type IL-9R intracellular domain, such as set forth in SEQ ID NO: 56. In other such embodiments, the modified IL-9R comprises a variant IL9R intracellular domain selected from IL9R(Large D2) (SEQ ID NO: 43), IL9R(Large D2’) (SEQ ID NO: 44) or IL9R(dl5) (SEQ ID NO: 32) and one or amino acid substitutions as represented by IL9R(Mut6YRPQ) (SEQ ID NO: 47), IL9R(Mut7YLPL) (SEQ ID NO: 48), or IL9R(Mut9YLKQ) (SEQ ID NO: 49). In particular embodiments, the variant IL9R intracellular domain is set forth in SEQ ID NO: 44.

[0331] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to any one of SEQ ID NOs: 153, 154, 155, 156, 157, 159 or 160. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises the amino acid sequence set forth in any one of SEQ ID NOs: 153, 154, 155, 156, 157, 159 or 160. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in any one of SEQ ID NOs: 153, 154, 155, 156, 157, 159 or 160.

[0332] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises domain comprises a sequence of amino acids that is at least about 70%, about75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 158. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises the amino acid sequence set forth in SEQ ID NO: 158. In some embodiments, the tethered IL- 9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 158.

[0333] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein is preceded by an N-terminal signal peptide sequence to control expression of the recombinant cytokine fusion receptor. In some embodiments, the signal peptide is native to IL-9. In some embodiments, the signal peptide is MLLAMVLTSALLLCSMAG (SEQ ID NO: 108). In some embodiments, the signal peptide is heterologous to IL-9.

[0334] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein lacks the signal peptide sequence, which is typically cleaved when the fusion protein is expressed by the cell, such as for expression on the cell surface as a transmembrane receptor.

[0335] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to any one of SEQ ID NOs: 161, 162, 163, 164, 165, 167 or 168. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises the amino acid sequence set forth in any one of SEQ ID NOs: 161, 162, 163, 164, 165, 167 or 168. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in any one of SEQ ID NOs: 161, 162, 163, 164, 165, 167 or 168.

[0336] In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises domain comprises a sequence of amino acids that is at least about 70%, about 75%, about 80%, about 85%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% identical to SEQ ID NO: 166. In some embodiments, the tethered IL-9 / IL-9R recombinant fusion protein comprises the amino acid sequence set forth in SEQ ID NO: 166. In some embodiments, the tethered IL- 9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 166.

[0337] In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 154or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 154 or 162. In some embodiments, the IL tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL- 9R comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 154 or 162. In some embodiments, the tethered IL- 9 / IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 154. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQID NO: 154. In some embodiments, the tethered IL-9 / IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 162. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 162.

[0338] In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL- 9R comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 97% identical to SEQ IDNO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 156 or 164. In some embodiments, the tethered IL-9 / IL- 9R comprises the amino acid sequence set forth in SEQ ID NO: 156. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 156. In some embodiments, the tethered IL-9 / IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 164. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 164.

[0339] In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL- 9R comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 160 or 168. In some embodiments, thetethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 160 or 168. In some embodiments, the tethered IL-9 / IL- 9R comprises the amino acid sequence set forth in SEQ ID NO: 160. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 160. In some embodiments, the tethered IL-9 / IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 168. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 168.

[0340] In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL- 9R comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of aminoacids that is at least about 90% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 158 or 166. In some embodiments, the tethered IL-9 / IL- 9R comprises the amino acid sequence set forth in SEQ ID NO: 158. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 158. In some embodiments, the tethered IL-9 / IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 166. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 166.

[0341] In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 86% identical to SEQ IDNO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL- 9R comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL- 9 / IL-9R comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL-9R comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 159 or 167. In some embodiments, the tethered IL-9 / IL- 9R comprises the amino acid sequence set forth in SEQ ID NO: 159. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 159. In some embodiments, the tethered IL-9 / IL-9R comprises the amino acid sequence set forth in SEQ ID NO: 167. In some embodiments, the tethered IL-9 / IL-9R consists of the amino acid sequence set forth in SEQ ID NO: 167.IL POLYNUCLEOTIDES AND VECTORS

[0342] Provided herein are polynucleotides encoding any of the recombinant fusion proteins disclosed herein. In some embodiments, the polynucleotide encodes any of the tethered IL9 / IL9R recombinant fusion proteins described in Section I.

[0343] The present disclosure further relates to variants of the polynucleotides disclosed herein. The polynucleotide variants can contain alterations in the coding regions, non-coding regions, or both.

[0344] In some embodiments, a polynucleotide variant comprising a nucleotide sequence that is at least about 75 %, about 80 %, about 85 %, about 90 %, about 91 %, about 92 %, about 93 %, about 94 %, about 95 %, about 96 %, about 97 %, about 98%, or about 99 % identical to the nucleotide sequence of a polynucleotide disclosed herein.

[0345] In some embodiments, a polynucleotide variant contains substitutions, additions, or deletions that alter the properties or activities of the encoded polypeptide. In some embodiments, a polynucleotide variant contains silent substitutions, additions, or deletions that does not alter the properties or activities of the encoded polypeptide. In some embodiments, a polynucleotide variant is produced to modulate or alter expression (or expression levels) of the encoded polypeptide. In some embodiments, a polynucleotide variant is produced to increase expression of the encoded polypeptide. In some embodiments, a polynucleotide variant is produced to decrease expression of the encoded polypeptide. In some embodiments, a polynucleotide variant has increased expression of the encoded polypeptide as compared to a parental polynucleotide sequence. In some embodiments, a polynucleotide variant has decreased expression of the encoded polypeptide as compared to a parental polynucleotide sequence.

[0346] In some embodiments, polynucleotides are codon-optimized. As used herein, the term “codon-optimized” refers to substituting codons in a polynucleotide encoding a polypeptide in order to increase the expression, stability and / or activity of the polypeptide. Factors that influence codon optimization include, but are not limited to one or more of: (i) variation of codon biases between two or more organisms or genes or synthetically constructed bias tables, (ii) variation in the degree of codon bias within an organism, gene, or set of genes, (iii) systematic variation of codons including context, (iv) variation of codons according to their decoding tRNAs, (v) variation of codons according to GC %, either overall or in one position of the triplet, (vi) variation in degree of similarity to a reference sequence for example a naturally occurring sequence, (vii) variation in the codon frequency cutoff, (viii) structural properties of mRNAs transcribed from the DNA sequence, (ix) prior knowledge about the function of the DNA sequences upon which design of the codon substitution set is to be based, (x) systematic variation of codon sets for each amino acid, (xi)isolated removal of spurious translation initiation sites and / or (xii) elimination of fortuitous poly adenylation sites otherwise leading to truncated RNA transcripts.

[0347] It will be appreciated by those of ordinary skill in the art that, as a result of the degeneracy of the genetic code, there are many nucleotide sequences that encode a polypeptide, or fragment of variant thereof, as described herein. Some of these polynucleotides bear minimal homology to the nucleotide sequence of any native gene. Nonetheless, polynucleotides that vary due to differences in codon usage are specifically contemplated in particular embodiments, for example polynucleotides that are optimized for human and / or primate codon selection. Further, alleles of the genes comprising the polynucleotide sequences provided herein may also be used. Alleles are endogenous genes that are altered as a result of one or more mutations, such as deletions, additions and / or substitutions of nucleotides.

[0348] The polynucleotides contemplated herein, regardless of the length of the coding sequence itself, may be combined with other DNA sequences, such as promoters and / or enhancers, untranslated regions (UTRs), signal sequences, Kozak sequences, polyadenylation signals, additional restriction enzyme sites, multiple cloning sites, internal ribosomal entry sites (IRES), recombinase recognition sites (e.g., LoxP, FRT, and Att sites), termination codons, transcriptional termination signals, and polynucleotides encoding self-cleaving polypeptides, epitope tags, as disclosed elsewhere herein or as known in the art, such that their overall length may vary considerably. It is therefore contemplated that a polynucleotide fragment of almost any length may be employed in particular embodiments, with the total length preferably being limited by the ease of preparation and use in the intended recombinant DNA protocol.

[0349] Polynucleotides can be prepared, isolated, purified, manipulated, and / or expressed using any of a variety of well-established techniques known and available in the art.

[0350] Also provided herein are vectors comprising the polynucleotides or nucleic acid molecules encoding the recombinant fusion proteins disclosed herein.

[0351] In order to express the recombinant fusion proteins described herein in a cell, an expression cassette encoding the recombinant fusion proteins can be inserted into a nucleic acid vector. The “expression cassette” contains the gene of interest. The cassette is positionally and sequentially oriented within the vector such that the nucleic acid in the cassette can be transcribed into RNA, and when necessary, translated into a protein or apolypeptide, undergo appropriate post-translational modifications required for activity in the host cell, and be translocated to the appropriate compartment for biological activity by targeting to appropriate intracellular compartments or secretion into extracellular compartments. Preferably, the cassette has its 3’ and 5’ ends adapted for ready insertion into a vector, e.g., it has restriction endonuclease sites at each end. The cassette can be removed and inserted into a plasmid or viral vector as a single unit.

[0352] In some embodiments, vectors include, without limitation, plasmids, phagemids, cosmids, transposons, artificial chromosomes such as yeast artificial chromosome (YAC), bacterial artificial chromosome (BAC), or Pl-derived artificial chromosome (PAC), bacteriophages such as lambda phage or M13 phage, and animal viruses. In some embodiments, the coding sequences of the recombinant fusion proteins disclosed herein can be ligated into such vectors for expression in mammalian cells.

[0353] In some embodiments, non- viral vectors are used to deliver one or more polynucleotides contemplated herein. In some embodiments, the recombinant vector comprising a polynucleotide encoding the recombinant fusion proteins described herein is a plasmid. Numerous suitable plasmid expression vectors are known to those of skill in the art, and many are commercially available. The following vectors are provided by way of example; for eukaryotic host cells: pXTl, pSG5 (Stratagene), pSVK3, pBPV, pMSG, and pSVLSV40 (Pharmacia). However, any other plasmid vector may be used so long as it is compatible with the host cell.

[0354] In some embodiments, viral vectors are used to deliver one or more polynucleotides contemplated herein. Suitable viral vectors include, but are not limited to, viral vectors based on adenovirus (see, e.g., Li et al., Invest Opthalmol Vis Sci 35:2543 2549, 1994; Borras et al., Gene Ther 6:515 524, 1999; Li and Davidson, PNAS 92:7700 7704, 1995; Sakamoto et al., H Gene Ther 5:1088 1097, 1999; WO 94 / 12649, WO 93 / 03769; WO 93 / 19191 ; WO 94 / 28938; WO 95 / 11984 and WO 95 / 00655); adeno-associated virus (see, e.g., U.S. Patent No. 7,078,387; Ali et al., Hum Gene Ther 9:81 86, 1998, Flannery et al„ PNAS 94:6916 6921 , 1997; Bennett et al., Invest Opthalmol Vis Sci 38:2857 2863, 1997; Jomary et al., Gene Ther 4:683 690, 1997, Rolling et al., Hum Gene Ther 10:641 648, 1999; Ali et al., Hum Mol Genet 5:591 594, 1996; Srivastava in WO 93 / 09239, Samulski et al., J. Vir. (1989) 63:3822-3828; Mendelson et al„ Virol. (1988) 166:154-165; and Flotte et al., PNAS (1993) 90:10613-10617); alphaviruses; arenaviruses; baculovirus; herpes simplexvirus; human immunodeficiency virus (see, e.g., Miyoshi et al., PNAS 94:10319 23, 1997; Takahashi et al., J Virol 73:78127816, 1999); poliovirus; poxvirus; retrovirus (e.g., Murine Leukemia Virus, spleen necrosis virus, and vectors derived from retroviruses such as Rous Sarcoma Virus, Harvey Sarcoma Virus, avian leukosis virus, a lentivirus, human immunodeficiency virus, myeloproliferative sarcoma virus, and mammary tumor virus); SV40; vaccinia virus; and the like. Examples of vectors are pClneo vectors (Promega) for expression in mammalian cells; pLenti4 / V5-DEST™, pLenti6 / V5-DEST™, and pLenti6.2 / V5-GW / lacZ (Invitrogen) for lentivirus-mediated gene transfer and expression in mammalian cells.

[0355] In some embodiments, the vector is a non-integrating vector, including but not limited to, an episomal vector or a vector that is maintained extrachromosomally. As used herein, the term “episomal” refers to a vector that is able to replicate without integration into host’s chromosomal DNA and without gradual loss from a dividing host cell also meaning that said vector replicates extrachromosomally or episomally. The vector is engineered to harbor the sequence coding for the origin of DNA replication or “ori” from a lymphotrophic herpes virus or a gamma herpesvirus, an adenovirus, SV40, a bovine papilloma virus, or a yeast, specifically a replication origin of a lymphotrophic herpes virus or a gamma herpesvirus corresponding to oriP of EBV. In some embodiments, the lymphotrophic herpes virus may be Epstein Barr virus (EBV), Kaposi’s sarcoma herpes virus (KSHV), Herpes virus saimiri (HS), or Marek’s disease virus (MDV). Epstein Barr virus (EBV) and Kaposi’s sarcoma herpes virus (KSHV) are also examples of a gamma herpesvirus. A viral vector delivered by such viruses or viral particles may be referred to by the type of virus to deliver the viral vector (e.g., a lentiviral vector is a viral vector that is to be delivered by a lentivirus). A viral vector can contain viral elements (e.g., nucleotide sequences) necessary for packaging of the viral vector into the virus or viral particle, replicating the virus, or other desired viral activities. A virus containing a viral vector may be replication competent, replication deficient or replication defective.

[0356] In some embodiments, the vector is an integrating vector. In some embodiments, a polynucleotide is introduced into a target or host cell using a transposon vector system. In some embodiments, the transposon vector system comprises a vector comprising transposable elements and a polynucleotide contemplated herein; and a transposase. In some embodiments, the transposon vector system is a single transposase vector system, see, e.g.,WO 2008 / 027384. Exemplary transposases include, but are not limited to: piggyBac, Sleeping Beauty, Mosl, Tcl / mariner, Tol2, mini-Tol2, Tc3, MuA, Himar I, Frog Prince, and derivatives thereof. The piggyBac transposon and transposase are described, for example, in U.S. Patent 6,962,810, which is incorporated herein by reference in its entirety. The Sleeping Beauty transposon and transposase are described, for example, in Izsvak et al., J. Mol. Biol. 302: 93-102 (2000), which is incorporated herein by reference in its entirety. The Tol2 transposon which was first isolated from the medaka fish Oryzias latipes and belongs to the hAT family of transposons is described in Kawakami et al. (2000). Mini-Tol2 is a variant of Tol2 and is described in Balciunas et al. (2006). The Tol2 and Mini-Tol2 transposons facilitate integration of a transgene into the genome of an organism when co-acting with the Tol2 transposase. The Frog Prince transposon and transposase are described, for example, in Miskey et al., Nucleic Acids Res. 31:6873-6881 (2003).

[0357] In some embodiments, a polynucleotide sequence encoding the recombinant fusion proteins disclosed herein is operably linked to one or more control elements that allow expression of the polynucleotide in both prokaryotic and eukaryotic cells. “Control elements” refer those non-translated regions of the vector which interact with host cellular proteins to carry out transcription and translation. Non-limiting examples of control elements include origin of replication, selection cassettes, constitutive and inducible promoters, enhancers, translation initiation signals (Shine Dalgamo sequence or Kozak sequence) introns, transcription terminators, 5’ and 3’ untranslated regions. See e.g., Bitter et al. (1987) Methods in Enzymology, 153:516-544) Such elements may vary in their strength and specificity. The transcriptional control element may be functional in either a eukaryotic cell (e.g., a mammalian cell) or a prokaryotic cell (e.g., bacterial, or archaeal cell).

[0358] In some embodiments, polynucleotides encoding the recombinant fusion proteins described herein are operably linked to a promoter and / or an enhancer. The term “promoter” as used herein refers to a recognition site of a polynucleotide (DNA or RNA) to which an RNA polymerase binds. An RNA polymerase initiates and transcribes polynucleotides operably linked to the promoter. In some embodiments, a promoter operative in mammalian cells comprise an AT-rich region located approximately 25 to 30 bases upstream from the site where transcription is initiated and / or another sequence found 70 to 80 bases upstream from the start of transcription, a CNCAAT region where N may be any nucleotide. The term “enhancer” refers to a segment of DNA which contains sequences capable of providingenhanced transcription and in some instances can function independent of their orientation relative to another control sequence. An enhancer can function cooperatively or additively with promoters and / or other enhancer elements.

[0359] Non-limiting examples of suitable eukaryotic promoters (promoters functional in a eukaryotic cell) include those from cytomegalovirus (CMV) immediate early, herpes simplex virus (HSV) thymidine kinase, a viral simian virus 40 (SV40) (e.g., early and late SV40), a spleen focus forming virus (SFFV) promoter, long terminal repeats (LTRs) from retrovirus (e.g., a Moloney murine leukemia virus (MoMLV) LTR promoter or a Rous sarcoma virus (RSV) LTR), a herpes simplex virus (HSV) (thymidine kinase) promoter, H5, P7.5, and Pl l promoters from vaccinia virus, an elongation factor 1-alpha (EFla) promoter, early growth response 1 (EGR1) promoter, a ferritin H (FerH) promoter, a ferritin L (FerL) promoter, a Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) promoter, a eukaryotic translation initiation factor 4A1 (EIF4A1) promoter, a heat shock 70kDa protein 5 (HSPA5) promoter, a heat shock protein 90kDa beta, member 1 (HSP90B1) promoter, a heat shock protein 70kDa (HSP70) promoter, a P-kinesin (P-KIN) promoter, the human ROSA 26 locus (Irions et al., Nature Biotechnology 25, 1477-1482 (2007)), a Ubiquitin C (UBC) promoter, a phosphoglycerate kinase- 1 (PGK) promoter, a cytomegalovirus enhancer / chicken P-actin (CAG) promoter, a P-actin promoter and a myeloproliferative sarcoma virus enhancer, negative control region deleted, dl587rev primer-binding site substituted (MND) promoter, and mouse metallothionein-1. Selection of the appropriate vector and promoter is well within the level of ordinary skill in the art.

[0360] In some embodiments, a polynucleotide sequence encoding the recombinant fusion proteins described herein is operably linked to a constitutive promoter. In such embodiments, the polynucleotides encoding the recombinant fusion proteins described herein are constitutively and / or ubiquitously expressed in a cell.

[0361] In some embodiments, the vector encodes the recombinant fusion protein and at least one additional transgene sequence. In some embodiments, the vector encodes the recombinant fusion protein and at least one additional transgene sequence, wherein the recombinant fusion protein and the at least one additional transgene sequence are separated by a multicistronic linker sequence. In some embodiments, the vector encodes from the 5’ to 3’ end, the recombinant fusion protein and at least one additional transgene sequence, wherein the recombinant fusion protein and the at least one additional transgene sequence areseparated by a multicistronic linker sequence. In some embodiments, the vector encodes from the 5’ to 3’ end, the at least one additional transgene sequence and the recombinant fusion protein, wherein the recombinant fusion protein and the at least one additional transgene sequence are separated by a multicistronic linker sequence.

[0362] In some embodiments, the multicistronic linker sequence is a 2A sequence. 2A sequences are small peptide sequences typically of 18-22 amino acids in length that mediate ribosome-skipping to allow for the generation of separate protein products from one polynucleotide. Specifically, the ribosome skipping results in cleaving of the 2A sequence such that the protein downstream of the 2A is attached to one proline at the N-terminus and the remaining 2A sequence is attached to the protein upstream of the 2A except for the C- terminal proline. In some embodiments, the 2A sequence is E2A (QCTNYALLKLAGDVESNPGP; SEQ ID NO: 186), F2A (VKQTLNFDLLKLAGDVESNPGP; SEQ ID NO: 187), P2A (ATNFSLLKQAGDVEENPGP; SEQ ID NO: 98) or T2A (EGRGSLLTCGDVEENPGP; SEQ ID NO: 188). In some embodiments, the 2A sequence is nucleotide sequence set forth in SEQ ID NO: 99.

[0363] In some embodiments, the at least one additional transgene is a recombinant antigen receptor. In some embodiments, the recombinant antigen receptor is a chimeric antigen receptor (CAR). In some embodiments, when the CAR is expressed by genetically engineered cells and is able to bind via its extracellular domain to the target domain (comprising the extracellular domain or truncated portion thereof of a target antigen) of the engineered cancer antigen. In some embodiments, the CAR further comprises a transmembrane domain and an intracellular signaling domain.

[0364] In some embodiments, the CAR is an anti-BCMA CAR. Chimeric antigen receptors containing anti-BCMA antibodies, and cells expressing such chimeric antigen receptors have been previously described. See Carpenter et al., Clin Cancer Res., 2013, 19(8):2048-2060, W02010104949, WO 2016090320, W02016090327, W02016094304, WO2016014789, WO2017173256, WO2017130223, WO2018028647, WO2019 / 089968, WO2019089969, W02019085102, WO2019241358, W02019108900, W02020014333, WO2020243546, W02020018825, W02020038147, WO2021091978, WO2021256724, WO2021057866, WO2021146147, WO2021121228, WO2021162394, WO2021231213, WO2022089353, W02022046730, W02022046730, WO2022143870, WO2022119923,WO2023226921, WO2023288185, WO2023193662, WO2023109257, WO2023016576, W02023020474, WO2023019398, WO2023068382, each of which is incorporated by reference in their entirety. Any anti-BCMA CAR previously described or known or based on any of such CARs can be used in the provided embodiments.

[0365] In some embodiments, the extracellular binding domain of the BCMA CAR comprises an scFv derived from Cl 1D5.3, a murine monoclonal antibody as described in Carpenter et al., Clin. Cancer Res. 19(8):2048-2060 (2013). See also PCT Application Publication No. WO2010 / 104949. The Cl lD5.3-derived scFv may comprise the heavy chain variable region (VH) and the light chain variable region (VL) of Cl 1D5.3. In some embodiments, the extracellular binding domain of the BCMA CAR comprises an scFv derived from another murine monoclonal antibody, C12A3.2, as described in Carpenter et al., Clin. Cancer Res. 19(8):2048-2060 (2013) and PCT Application Publication No.WO2010 / 104949. In some embodiments, the extracellular binding domain of the BCMA CAR comprises a murine monoclonal antibody with high specificity to human BCMA, referred to as BB2121 in Friedman et al., Hum. Gene Ther. 29(5):585-601 (2018)). See also, PCT Application Publication No. WO2012163805. BB2121 is also known as anti-BCMA02 CAR. In some embodiments, the extracellular binding domain of the BCMA CAR comprises single variable fragments of two heavy chains (VHH) that can bind to two epitopes of BCMA as described in Zhao et al., J. Hematol. Oncol. 11(1): 141 (2018), also referred to as LCAR- B38M. See also, PCT Application Publication No. WO2018 / 028647. In some embodiments, the extracellular binding domain of the BCMA CAR comprises a fully human heavy-chain variable domain (FHVH) as described in Lam et al., Nat. Commun. 11(1):283 (2020), also referred to as FHVH33. In some embodiments, the extracellular binding domain of the BCMA CAR comprises an scFv derived from CT103A (or CAR0085) as described in U.S. Patent No. 11,026,975 B2. In some embodiments, the CAR comprises an anti-BCMA CAR of a commercial CAR cell therapy. Non-limiting examples of an anti-BCMA CAR in commercial cell-based therapies include the anti-BCMA CAR engineered in cells of idecabtagene vicleucel (AB ECM A®) or ciltacabtagene autoleucel (CARVYKTI™).

[0366] In some embodiments, the CAR is an anti-CD19 CAR. Chimeric antigen receptors containing anti-CD19 antibodies, and cells expressing such chimeric antigen receptors have been previously described. In some embodiments, the extracellular binding domain of the CD 19 CAR is from a mouse derived antibody FMC63. In some embodiments, theextracellular binding domain of the CD 19 CAR is from a mouse derived antibody SJ25C1. In some embodiments, the CAR comprises an anti-CD19 CAR of a commercial CAR cell therapy. Non-limiting examples of an anti-CD19 CAR in commercial cell-based therapies include the anti-CD19 CAR engineered in cells of YESCARTA®, KYMRIAH®, TECARTUS®, or BREYANZI®.

[0367] In some embodiments, the CAR is an anti-CD20 CAR. Chimeric antigen receptors containing anti-CD20 antibodies, and cells expressing such chimeric antigen receptors have been previously described. See WO2022 / 221698, US18 / 473,965, WO2023 / 239338, CN109593137, W02020 / 151752, and US 11834511.

[0368] In some embodiments, the CAR is an anti-CD22 CAR. Chimeric antigen receptors containing anti-CD22 antibodies, and cells expressing such chimeric antigen receptors have been previously described. See WO2023 / 239338, WO2020 / 151752, US20220047633, CN116554326, WO2022 / 181992, W02023 / 090704, and US11878052.

[0369] In some embodiments, the CAR is an anti-CD70 CAR. Chimeric antigen receptors containing anti-CD70 antibodies, and cells expressing such chimeric antigen receptors have been previously described. See EP4281483, US20220411478, US20220347217, US20230399412, US20230355761, and W02020 / 108643.

[0370] In some embodiments, the CAR is a CAR comprising a sequence that has at least 85%, at least 86%, at least 87%, at least 88%, at least 89%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99%, or at least 100% sequence identity to SEQ ID NO: 146. In some embodiments, the CAR comprises the sequence set forth in SEQ ID NO: 146.

[0371] In some embodiments, a polynucleotide sequence encoding the recombinant fusion proteins described herein is operably linked to an inducible promoter. In such embodiments, polynucleotides encoding the recombinant fusion proteins described herein are conditionally expressed. As used herein, “conditional expression” may refer to any type of conditional expression including, but not limited to, inducible expression; repressible expression; expression in cells or tissues having a particular physiological, biological, or disease state (e.g., cell type or tissue specific expression) etc. Illustrative examples of inducible promoters / systems include, but are not limited to, steroid-inducible promoters such as promoters for genes encoding glucocorticoid or estrogen receptors (inducible by treatment with the corresponding hormone), metallothionine promoter (inducible by treatment withvarious heavy metals), MX-1 promoter (inducible by interferon), the “GeneSwitch” mifepristone-regulatable system (Sirin et al., 2003, Gene, 323:67), the cumate inducible gene switch (WO 2002 / 088346), tetracycline-dependent regulatory systems, etc.

[0372] In some embodiments, the vectors described herein further comprise a transcription termination signal. Elements directing the efficient termination and polyadenylation of the heterologous nucleic acid transcripts increases heterologous gene expression. Transcription termination signals are generally found downstream of the polyadenylation signal. In some embodiments, vectors comprise a poly adenylation sequence 3’ of a polynucleotide encoding a polypeptide to be expressed. The term “polyA site” or “polyA sequence” as used herein denotes a DNA sequence which directs both the termination and polyadenylation of the nascent RNA transcript by RNA polymerase II. Polyadenylation sequences can promote mRNA stability by addition of a polyA tail to the 3’ end of the coding sequence and thus, contribute to increased translational efficiency. Cleavage and polyadenylation are directed by a poly(A) sequence in the RNA. The core poly(A) sequence for mammalian pre-mRNAs has two recognition elements flanking a cleavage- polyadenylation site. Typically, an almost invariant AAUAAA hexamer lies 20-50 nucleotides upstream of a more variable element rich in U or GU residues. Cleavage of the nascent transcript occurs between these two elements and is coupled to the addition of up to 250 adenosines to the 5’ cleavage product. In some embodiments, the core poly(A) sequence is an ideal polyA sequence (e.g., AATAAA, ATT AAA, AGTAAA). In some embodiments, the poly (A) sequence is an SV40 polyA sequence, a bovine growth hormone polyA sequence (BGHpA), a rabbit P-globin polyA sequence (rPgpA), variants thereof, or another suitable heterologous or endogenous polyA sequence known in the art.

[0373] In some embodiments, a vector may also comprise a sequence encoding a signal peptide (e.g., for nuclear localization, nucleolar localization, mitochondrial localization), fused to the polynucleotide encoding the recombinant fusion proteins. For example, a vector may comprise a nuclear localization sequence (e.g., from SV40) fused to the polynucleotide encoding the recombinant fusion proteins. In some embodiments, the signal peptide is an Igk signal peptide. In some embodiments, the signal peptide is a CD8 signal peptide. In some embodiments, the signal peptide comprises a sequence set forth in SEQ ID NO: 103. In some embodiments, the signal peptide comprises a murine signal peptide sequence set forth in SEQID NO: 147. In some embodiments, the signal peptide comprises a human signal peptide sequence set forth in SEQ ID NO: 148.

[0374] The expression vector may also include nucleotide sequences encoding protein tags (e.g., Flag tag, 6xHis tag, hemagglutinin tag, green fluorescent protein, etc.) that are fused to the site-directed modifying polypeptide, thus resulting in a chimeric polypeptide. In some embodiments, the FLAG tag comprises a sequence set forth in SEQ ID NO: 102.

[0375] Methods of introducing polynucleotides and recombinant vectors into a host cell are known in the art. Suitable methods include e.g., viral or bacteriophage infection, transfection, conjugation, protoplast fusion, lipofection, electroporation, calcium phosphate precipitation, polyethyleneimine (PEI)-mediated transfection, DEAE-dextran mediated transfection, liposome-mediated transfection, particle gun technology, calcium phosphate precipitation, direct micro injection, nanoparticle-mediated nucleic acid delivery (see, e.g., Panyam et al., Adv Drug Deliv Rev. 2012 Sep 13. pii: S0169-409X(12)00283-9), microfluidics delivery methods (See e.g., International PCT Publication No. WO 2013 / 059343), and the like.

[0376] In some embodiments, delivery via electroporation comprises mixing the cells with the polynucleotides encoding the recombinant fusion proteins in a cartridge, chamber, or cuvette and applying one or more electrical impulses of defined duration and amplitude. In some embodiments, cells are mixed with polynucleotides encoding the recombinant fusion proteins in a vessel connected to a device (e.g., a pump) which feeds the mixture into a cartridge, chamber, or cuvette wherein one or more electrical impulses of defined duration and amplitude are applied, after which the cells are delivered to a second vessel. Illustrative examples of polynucleotide delivery systems suitable for use in particular embodiments contemplated include, but are not limited to, those provided by Amaxa Biosystems, Maxcyte, Inc., BTX Molecular Delivery Systems, NeonTM Transfection Systems, and Copernicus Therapeutics Inc. Lipofection reagents are sold commercially (e.g., Transfectam™ and Lipofectin™). Cationic and neutral lipids that are suitable for efficient lipofection of polynucleotides have been described in the literature. See e.g., Liu et al. (2003) Gene Therapy. 10:180-187; and Balazs et al. (2011) Journal of Drug Delivery. 2011:1-12.

[0377] In some embodiments, polynucleotides encoding the recombinant fusion proteins described herein are introduced to a cell in a non-viral delivery vehicle, such as a transposon, a nanoparticle (e.g., a lipid nanoparticle), a liposome, an exosome, an attenuated bacterium,or a virus-like particle. In some embodiments, the vehicle is an attenuated bacterium (e.g., naturally, or artificially engineered to be invasive but attenuated to prevent pathogenesis including Listeria monocytogenes, certain Salmonella strains, Bifidobacterium longum, and modified Escherichia coli), bacteria having nutritional and tissue-specific tropism to target specific cells, and bacteria having modified surface proteins to alter target cell specificity. In some embodiments, the vehicle is a genetically modified bacteriophage (e.g., engineered phages having large packaging capacity, less immunogenicity, containing mammalian plasmid maintenance sequences and having incorporated targeting ligands). In some embodiments, the vehicle is a biological liposome. For example, the biological liposome is a phospholipid-based particle derived from human cells (e.g., erythrocyte ghosts, which are red blood cells broken down into spherical structures derived from the subject and wherein tissue targeting can be achieved by attachment of various tissue or cell-specific ligands), secretory exosomes, or subject derived membrane-bound nanovescicles (30 -100 nm) of endocytic origin (e.g., can be produced from various cell types and can therefore be taken up by cells without the need for targeting ligands).

[0378] In some embodiments, vectors comprising polynucleotides encoding the recombinant fusion proteins described herein are introduced to cells by viral delivery methods, e.g., by viral transduction. A number of viral based systems have been developed for gene transfer into mammalian cells. For example, retroviruses provide a convenient platform for gene delivery systems. The heterologous nucleic acid can be inserted into a vector and packaged in retroviral particles using techniques known in the art. The recombinant virus can then be isolated and delivered to the engineered mammalian cell in vitro or ex vivo. A number of retroviral systems are known in the art. In some embodiments, adenovirus vectors are used. A number of adenovirus vectors are known in the art. In some embodiments, lentivirus vectors are used. In some embodiments, self-inactivating lentiviral vectors are used. For example, self-inactivating lentiviral vectors carrying the immunomodulator (such as immune checkpoint inhibitor) coding sequence and / or selfinactivating lentiviral vectors carrying chimeric antigen receptors can be packaged with protocols known in the art. The resulting lentiviral vectors can be used to transduce a mammalian cell (such as primary human T cells) using methods known in the art. Vectors derived from retroviruses such as lentivirus are suitable tools to achieve long-term gene transfer, because they allow long-term, stable integration of a transgene and its propagation inprogeny cells. Lentiviral vectors also have low immunogenicity and can transduce nonproliferating cells.

[0379] In some embodiments, the vehicle is a mammalian virus-like particle. For example, modified viral particles can be generated (e.g., by purification of the “empty” particles followed by ex vivo assembly of the virus with the desired cargo).A. Exemplary Tethered IL9 / IL9R Cytokine Receptors and CAR Constructs

[0380] Among provided recombinant fusion proteins are tethered IL9 / IL9R comprising IL-9, a peptide linker, and a modified IL-9R and an additional transgene. In some embodiments, the at least one additional transgene is a recombinant antigen receptor. In some embodiments, the recombinant antigen receptor is a chimeric antigen receptor (CAR). In some embodiments, when the CAR is expressed by genetically engineered cells and is able to bind via its extracellular domain to the target domain (comprising the extracellular domain or truncated portion thereof of a target antigen) of the engineered cancer antigen. In some embodiments, the CAR further comprises a transmembrane domain and an intracellular signaling domain.

[0381] In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 89% identicalto SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the amino acid sequence set forth in SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the amino acid sequence set forth in SEQ ID NO: 150. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 70% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 75% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 80% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 85% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is atleast about 86% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 87% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 88% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 89% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 90% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 91% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 92% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 93% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 94% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 95% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 96% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 97% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 98% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 99% identical to SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the nucleic acid sequence set forth in SEQ ID NO: 149. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the nucleic acid sequence set forth in SEQ ID NO: 149.

[0382] In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 152.In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the amino acid sequence set forth in SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consistsof the amino acid sequence set forth in SEQ ID NO: 152. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 70% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 75% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 80% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 85% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 86% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 87% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 88% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 89% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 90% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 91% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 92% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 93% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 94% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 95% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 96% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 97% identical to SEQ ID NO: 151. In some embodiments,the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 98% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 99% identical to SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the nucleic acid sequence set forth in SEQ ID NO: 151. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the nucleic acid sequence set forth in SEQ ID NO: 151.

[0383] In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR constructcomprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the amino acid sequence set forth in SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the amino acid sequence set forth in SEQ ID NO: 170. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 70% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 75% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 80% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 85% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 86% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 87% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 88% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 89% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 90% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9Rand CAR construct comprises a sequence of nucleic acids that is at least about 91% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 92% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 93% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 94% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 95% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 96% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 97% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 98% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 99% identical to SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the nucleic acid sequence set forth in SEQ ID NO: 169. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the nucleic acid sequence set forth in SEQ ID NO: 169.

[0384] In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence ofamino acids that is at least about 87% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the amino acid sequence set forth in SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the amino acid sequence set forth in SEQ ID NO: 172. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 70% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 75% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR constructcomprises a sequence of nucleic acids that is at least about 80% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 85% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 86% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 87% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 88% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 89% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 90% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 91% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 92% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 93% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 94% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 95% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 96% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 97% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 98% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 99% identical to SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the nucleic acid sequence set forth in SEQ ID NO: 171. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the nucleic acid sequence set forth in SEQ ID NO: 171.

[0385] In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR constructcomprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the amino acid sequence set forth in SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the amino acid sequence set forth in SEQ ID NO: 174. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 70% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 75% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 80% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 85% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 86% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 87% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 88% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 89% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 90% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 91% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 92% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 93% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 94% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9Rand CAR construct comprises a sequence of nucleic acids that is at least about 95% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 96% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 97% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 98% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 99% identical to SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the nucleic acid sequence set forth in SEQ ID NO: 173. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the nucleic acid sequence set forth in SEQ ID NO: 173.

[0386] In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence ofamino acids that is at least about 91% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the amino acid sequence set forth in SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the amino acid sequence set forth in SEQ ID NO: 176. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 70% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 75% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 80% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 85% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 86% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 87% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR constructcomprises a sequence of nucleic acids that is at least about 88% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 89% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 90% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 91% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 92% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 93% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 94% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 95% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 96% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 97% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 98% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 99% identical to SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the nucleic acid sequence set forth in SEQ ID NO: 175. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the nucleic acid sequence set forth in SEQ ID NO: 175.

[0387] In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is atleast about 80% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the amino acid sequence set forth in SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the amino acid sequence set forth in SEQ ID NO: 178. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%,97%, 98%, 99% or more sequence identity to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 70% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 75% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 80% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 85% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 86% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 87% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 88% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 89% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 90% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 91% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 92% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 93% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 94% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 95% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 96% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 97% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 98% identical to SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 99% identicalto SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the nucleic acid sequence set forth in SEQ ID NO: 177. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the nucleic acid sequence set forth in SEQ ID NO: 177.

[0388] In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 180. In some embodiments,the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the amino acid sequence set forth in SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the amino acid sequence set forth in SEQ ID NO: 180. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 70% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 75% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 80% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 85% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 86% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 87% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 88% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 89% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 90% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 91% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 92% identical to SEQ ID NO: 179.In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 93% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 94% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 95% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 96% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 97% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 98% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 99% identical to SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the nucleic acid sequence set forth in SEQ ID NO: 179. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the nucleic acid sequence set forth in SEQ ID NO: 179.

[0389] In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9Rand CAR construct comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the amino acid sequence set forth in SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the amino acid sequence set forth in SEQ ID NO: 182. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 70% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 75% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 80% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 85% identical to SEQ ID NO: 181. In some embodiments,the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 86% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 87% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 88% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 89% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 90% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 91% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 92% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 93% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 94% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 95% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 96% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 97% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 98% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 99% identical to SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the nucleic acid sequence set forth in SEQ ID NO: 181. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the nucleic acid sequence set forth in SEQ ID NO: 181.

[0390] In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR constructcomprises a sequence of amino acids that is at least about 70% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 75% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 80% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 85% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 86% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 87% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 88% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 89% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 90% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 91% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 92% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 93% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 94% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 95% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 96% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 97% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 98% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of amino acids that is at least about 99% identical to SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the amino acid sequence set forth inSEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the amino acid sequence set forth in SEQ ID NO: 184. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that exhibits at least about 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or more sequence identity to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 70% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 75% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 80% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 85% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 86% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 87% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 88% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 89% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 90% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 91% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 92% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 93% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 94% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 95% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 96% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence ofnucleic acids that is at least about 97% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 98% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises a sequence of nucleic acids that is at least about 99% identical to SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct comprises the nucleic acid sequence set forth in SEQ ID NO: 183. In some embodiments, the tethered IL-9 / IL-9R and CAR construct consists of the nucleic acid sequence set forth in SEQ ID NO: 183.III. ENGINEERED CELLS AND POPULATION OF CELLS

[0391] Provided herein are cells engineered by vectors comprising the polynucleotides or nucleic acid molecules encoding the recombinant fusion proteins. Also provided herein are a population of cells comprising at least one such engineered cell.

[0392] In some aspects, provided herein is an engineered cell expressing one or more recombinant fusion proteins, wherein the recombinant fusion proteins comprises an extracellular domain (e.g., any as described in Section I.C), a transmembrane domain (e.g., any as described in Section I.D), and an interleukin 9 receptor (IL-9R) intracellular domain (e.g., any as described in Section I.E.

[0393] In some aspects, provided herein is an engineered cell expressing one or more constructs expressing recombinant fusion proteins and CAR construct as described Section II.A.

[0394] In some embodiments, the recombinant fusion proteins expressed by the cell is a constitutively active cytokine receptor. In some embodiments, the recombinant fusion proteins elicit signaling through STAT1, STAT3, and STAT5 pathways.

[0395] In some embodiments, the engineered cell is an immune effector cell. In some embodiments, the immune effector cell is a cytotoxic T cell. In some embodiments, the immune effector cell is a natural killer cell. In some embodiments, the immune effector cell is an animal cell or is derived from an animal cell, including invertebrate animals and vertebrate animals (e.g., fish, amphibian, reptile, bird, or mammal). In some embodiments, the immune effector cell is a mammalian cell or is derived from a mammalian cell (e.g., a pig, a cow, a goat, a sheep, a rodent, a non-human primate, a human, etc.). In some embodiments, the immune effector cell is a human cell or is derived from a human cell.

[0396] In some aspects, provided herein is a population of cells comprising at least one of the engineered cells provided herein.

[0397] In some aspects, provided herein is a method of engineering a cell to express any of the recombinant fusion proteins provided herein. In some embodiments, the method comprises contacting the cell with any of the polynucleotides or vectors provided herein.

[0398] Producing the engineered cells comprising obtaining a population of unengineered cells from a subject and contacting the cells with polynucleotides encoding the recombinant fusion proteins disclosed herein or vectors comprising such polynucleotides. In some embodiments, the population of unengineered cells are autologous. The term “autologous” in this context refers to cells that have been derived from the same subject to which they are administered. For example, immune effector cells may be obtained from a subject, engineered ex vivo, and then administered to the same subject in order to treat a disease. In some embodiments, the population of unengineered cells are allogeneic. The term “allogenic” in this context refers to cells that have been derived from one subject and are administered to another subject. For example, immune effector cells may be obtained from a first subject, engineered ex vivo, and then administered to a second subject in order to treat a disease such as a cancer.

[0399] In some embodiments, the engineered cells described herein further comprise an exogenous transgene encoding a detectable tag. Examples of detectable tags include but are not limited to, FLAG tags, poly-histidine tags (e.g. 6xHis), SNAP tags, Halo tags, cMyc tags, glutathione-S-transferase tags, avidin, enzymes, fluorescent proteins, luminescent proteins, chemiluminescent proteins, bioluminescent proteins, and phosphorescent proteins. In some embodiments the fluorescent protein is selected from the group consisting of blue / UV proteins (such as BFP, TagBFP, mTagBFP2, Azurite, EBFP2, mKalamal, Sirius, Sapphire, and T-Sapphire); cyan proteins (such as CFP, eCFP, Cerulean, SCFP3A, mTurquoise, mTurquoise2, monomeric Midoriishi-Cyan, TagCFP, and mTFPl); green proteins (such as: GFP, eGFP, meGFP (A208K mutation), Emerald, Superfolder GFP, Monomeric Azami Green, TagGFP2, mUKG, mWasabi, Clover, and mNeonGreen); yellow proteins (such as YFP, eYFP, Citrine, Venus, SYFP2, and TagYFP); orange proteins (such as Monomeric Kusabira-Orange, IUKOK, mK02, mOrange, and mOrange2); red proteins (such as RFP, mRaspberry, mCherry, mStrawberry, mTangerine, tdTomato, TagRFP, TagRFP-T, mApple, mRuby, and mRuby2); far-red proteins (such as mPlum, HcRed-Tandem, mKate2,mNeptune, and NirFP); near-infrared proteins (such as TagRFP657, IFP1.4, and iRFP); long stokes shift proteins (such as mKeima Red, LSS-mKatel, LSS-mKate2, and mBeRFP); photoactivatible proteins (such as PA-GFP, PamCherryl, and PATagRFP); photoconvertible proteins (such as Kaede (green), Kaede (red), KikGRl (green), KikGRl (red), PS-CFP2, PS- CFP2, mEos2 (green), mEos2 (red), mEos3.2 (green), mEos3.2 (red), PsmOrange, and PsmOrange); and photo switchable proteins (such as Dronpa). In some embodiments, the detectable tag can be selected from AmCyan, AsRed, DsRed2, DsRed Express, E2-Crimson, HcRed, ZsGreen, ZsYellow, mCherry, mStrawberry, mOrange, mBanana, mPlum, mRasberry, tdTomato, DsRed Monomer, and / or AcGFP, all of which are available from Clontech.

[0400] In some embodiments, the engineered cells described herein further comprise an exogenous transgene encoding a safety-switch system. Safety-switch systems (also referred to in the art as suicide gene systems) comprise exogenous transgenes encoding for one or more proteins that enable the elimination of an engineered immune effector cell after the cell has been administered to a subject. Examples of safety-switch systems are known in the art. For example, safety-switch systems include genes encoding for proteins that convert nontoxic pro-drugs into toxic compounds such as the Herpes simplex thymidine kinase (Hsv-tfc) and ganciclovir (GCV) system (Hsv-tfc / GCV). Hsv-tfc converts non-toxic GCV into a cytotoxic compound that leads to cellular apoptosis. As such, administration of GCV to a subject that has been treated with the engineered cells comprising a transgene encoding the Hsv-tfc protein can selectively eliminate the engineered cells while sparing endogenous immune effector cells. (See e.g., Bonini et al., Science, 1997, 276(5319): 1719- 1724; Ciceri et al., Blood, 2007, 109(11): 1828-1836; Bondanza et al., Blood 2006, 107(5): 1828-1836).

[0401] Additional safety-switch systems include genes encoding for cell-surface markers, enabling elimination of engineered cells by administration of a monoclonal antibody specific for the cell-surface marker via ADCC. In some embodiments, the cell-surface marker is CD20 and the engineered cells can be eliminated by administration of an anti-CD20 monoclonal antibody such as Rituximab (See e.g., Introna et al., Hum Gene Ther, 2000, 11 (4) :611-620; Serafini et al., Hum Gene Ther, 2004, 14, 63-76; van Meerten et al., Gene Ther, 2006, 13, 789-797). Similar systems using EGF-R and Cetuximab or Panitumumab are described in International PCT Publication No. WO 2018006880. Additional safety-switch systems include transgenes encoding pro-apoptotic molecules comprising one or moreI llbinding sites for a chemical inducer of dimerization (CID), enabling elimination of engineered cells by administration of a CID which induces oligomerization of the pro- apoptotic molecules and activation of the apoptosis pathway. In some embodiments, the pro- apoptotic molecule is Fas (also known as CD95) (Thomis et al., Blood, 2001, 97(5), 1249- 1257). In some embodiments, the pro-apoptotic molecule is caspase-9 (Straathof et al., Blood, 2005, 105(11), 4247-4254).

[0402] In some embodiments, the engineered cells described herein further expresses at least one different type of engineered receptor. In some embodiments, the at least one different type of engineered receptor is an engineered antigen- specific receptor recognizing a protein target expressed by a target cell, such as a tumor cell or an antigen presenting cell (APC).

[0403] In some embodiments, the at least one different type of engineered receptor is a chimeric antigen receptor (CAR). In some embodiments, the at least one different type of engineered receptor is an engineered T-cell receptor (TCR).

[0404] In some embodiments, the extracellular domain of the CAR or the TCR binds to an antigen expressed on a cancer cell. In some embodiments, the extracellular domain of the CAR or the TCR binds to an idiotype of an antibody. In some embodiments, the antibody is against an antigen expressed on a cancer cell. In some embodiments, the antigen is selectively expressed or overexpressed on a cancer cell, as compared to normal or non-targeted cells or tissues. In some embodiments, the cancer cell is a blood cancer cell or a solid tumor cancer cell.

[0405] In some embodiments, the antigen selected from a cluster of differentiation molecule, such as CD3, CD4, CD8, CD16, CD24, CD25, CD33, CD34, CD45, CD64, CD71, CD78, CD80 (also known as B7-1), CD86 (also known as B7-2), CD96, CD116, CD117, CD123, CD133, and CD138, CD371 (also known as CLL1); a tumor-associated surface antigen, such as 5T4, BCMA (also known as CD269 and TNFRSF17, UniProt# Q02223), carcinoembryonic antigen (CEA), carbonic anhydrase 9 (CAIX or MN / CAIX), CD19, CD20, CD22, CD30, CD40, disialogangliosides such as GD2, ELF2M, ductal-epithelial mucin, ephrin B2, epithelial cell adhesion molecule (EpCAM), ErbB2 (HER2 / neu), FCRL5 (UniProt# Q68SN8), FKBP11 (UniProt# Q9NYL4), glioma-associated antigen, glyco sphingolipids, gp36, GPRC5D (UniProt# Q9NZD1), mut hsp70-2, intestinal carboxyl esterase, IGF-I receptor, ITGA8 (UniProt# P53708), KAMP3, LAGE- la, MAGE,mesothelin, neutrophil elastase, NKG2D, Nkp30, NY-ESO-1, PAP, prostase, prostatecarcinoma tumor antigen-1 (PCTA-1), prostate specific antigen (PSA), PSMA, prostein, RAGE-1, R0R1, RU1 (SFMBT1), RU2 (DCDC2), SLAMF7 (UniProt# Q9NQ25), survivin, TAG-72, and telomerase; a major histocompatibility complex (MHC) molecule presenting a tumor- specific peptide epitope; tumor stromal antigens, such as the extra domain A (EDA) and extra domain B (EDB) of fibronectin; the Al domain of tenascin-C (TnC Al) and fibroblast associated protein (FAP); cytokine receptors, such as epidermal growth factor receptor (EGFR), EGFR variant III (EGFRvIII), TFGP-R or components thereof such as endoglin; a major histocompatibility complex (MHC) molecule; a virus- specific surface antigen such as an HIV-specific antigen (such as HIV gpl20); an EBV-specific antigen, a CMV-specific antigen, a HPV-specific antigen, a Lassa virus-specific antigen, an Influenza virus-specific antigen as well as any derivate or variant of these surface antigens.

[0406] In some embodiments, the at least one different type of engineered receptor is a chimeric antigen receptor. In some embodiments, the extracellular domain of the chimeric antigen receptor binds to an antigen expressed on a cancer cell. In some embodiments, the extracellular domain of the chimeric antigen receptor binds to an idiotype of an antibody. In some embodiments, the antibody is against an antigen expressed on a cancer cell. In some embodiments, the cancer cell is a blood cancer cell or a solid tumor cancer cell. In some embodiments, the cancer cell is a blood cancer cell. In some embodiments, the cancer cell is a solid tumor cancer cell.

[0407] A CAR generally includes an extracellular antigen binding domain, such as a portion of an antibody molecule, generally a variable heavy (Vn) chain region and / or variable light (VL) chain region of the antibody, e.g., an scFv antibody fragment.

[0408] In some embodiments, the CAR is constructed with a specificity for the particular antigen, such as an antigen expressed in a particular cell type to be targeted by adoptive therapy, e.g., a cancer marker, and / or an antigen intended to induce a dampening response, such as an antigen expressed on a normal or non-diseased cell type. Thus, the CAR typically includes in its extracellular portion one or more antigen binding molecules, such as one or more antigen-binding fragment, domain, or portion, or one or more antibody variable domains, and / or antibody molecules. In some embodiments, the CAR includes an antigenbinding portion or portions of an antibody molecule, such as a single-chain antibody fragment(scFv) derived from the variable heavy (VH) and variable light (VL) chains of a monoclonal antibody (mAb).

[0409] In some embodiments, the antibody or antigen-binding portion thereof is expressed on cells as part of a recombinant receptor, such as a chimeric receptor (e.g., CAR), that binds, such as specifically binds, to the antigen. Among the antigens targeted by the chimeric receptors are those expressed in the context of a disease, condition, or cell type to be targeted via the adoptive cell therapy. Among the diseases and conditions are proliferative, neoplastic, and malignant diseases and disorders, including cancers and tumors, including hematologic cancers, cancers of the immune system, such as lymphomas, leukemias, and / or myelomas, such as B, T, and myeloid leukemias, lymphomas, and multiple myelomas.

[0410] A CAR comprises an extracellular antigen binding domain fused via hinge and transmembrane domains to a cytoplasmic domain comprising a signaling domain.

[0411] In some embodiments, the CAR extracellular domain binds to an antigen expressed by a target cell in an MHC-independent manner. In some embodiments, the extracellular domain of a CAR recognizes a tag fused to an antibody or antigen-binding fragment thereof. In such embodiments, the antigen- specificity of the CAR is dependent on the antigen- specificity of the labeled antibody, such that a single CAR construct can be used to target multiple different antigens by substituting one antibody for another (See e.g., US Patent Nos. 9,233,125 and 9,624,279; US Patent Application Publication Nos. 20150238631 and 20180104354). In some embodiments, the extracellular domain of a CAR may comprise an antigen binding fragment derived from an antibody. Antigen binding domains that are useful in the present disclosure include, for example, scFvs; antibodies; antigen binding regions of antibodies; variable regions of the heavy / light chains; and single chain antibodies.

[0412] In some embodiments, the intracellular signaling domain of a CAR may be derived from the TCR complex zeta chain (such as CD3^ signaling domains), FcyRIII, FcsRI, or the T-lymphocyte activation domain. In some embodiments, the intracellular signaling domain of a CAR further comprises a costimulatory domain, for example a 4- IBB, CD28, CD40, MyD88, or CD70 domain. In some embodiments, the intracellular signaling domain of a CAR comprises two costimulatory domains, for example any two of 4- IBB, CD28, CD40, MyD88, or CD70 domains. Exemplary CAR structures and intracellular signaling domains are known in the art (See e.g., WO 2009 / 091826; US 20130287748; WO 2015 / 142675; WO 2014 / 055657; and WO 2015 / 090229, incorporated herein by reference).

[0413] CARs specific for a variety of tumor antigens are known in the art, for example CD 171 -specific CARs (Park et al., Mol Ther (2007) 15(4):825-833), EGFRvIII- specific CARs (Morgan et al., Hum Gene Ther (2012) 23(10): 1043-1053), EGF-R- specific CARs (Kobold et al., J Natl Cancer Inst (2014) 107(l):364), carbonic anhydrase K-specific CARs (Larners et al., Biochem Soc Trans (2016) 44(3):951-959), FR-a-specific CARs (Kershaw et al., Clin Cancer Res (2006) 12(20):6106-6015), HER2-specific CARs (Ahmed et al., J Clin Oncol (2015) 33(15)1688-1696;Nakazawa et al., Mol Ther (2011) 19(12):2133-2143; Ahmed et al., Mol Ther (2009) 17(10):1779-1787; Luo et al., Cell Res (2016) 26(7):850-853; Morgan et al., Mol Ther (2010) 18(4):843-851 ; Grada et al., Mol Ther Nucleic Acids (2013) 9(2):32), CEA-specific CARs (Katz et al., Clin Cancer Res (2015) 21( 14):3149-3159), IL13Ra2-specific CARs (Brown et al., Clin Cancer Res (2015) 21(18):4062-4072), GD2- specific CARs (Louis et al., Blood (2011) 118(23):6050-6056; Caruana et al., Nat Med (2015) 21(5):524-529), ErbB 2- specific CARs (Wilkie et al., J Clin Immunol (2012) 32(5): 1059-1070), VEGF-R- specific CARs (Chinnasamy et al., Cancer Res (2016) 22(2):436-447), FAP-specific CARs (Wang et al., Cancer Immunol Res (2014) 2(2): 154- 166), MSLN-specific CARs (Moon et al, Clin Cancer Res (2011) 17(14):4719-30), NKG2D- specific CARs (VanSeggelen et al., Mol Ther (2015) 23(10):1600-1610), CD19-specific CARs (Axicabtagene ciloleucel (Yescarta®) and Tisagenlecleucel (Kymriah®). See also4Li et al., J Hematol and Oncol (2018) 11(22), reviewing clinical trials of tumor- specific CARs.

[0414] In some embodiments, the CAR may include, but is not limited to a CAR engineered into cells of idecabtagene vicleucel (ABECMA®), Orvacabtagene Autoleucel (JCARH125), ciltacabtagene autoleucel (CARVYKTI™, also called NJ-68284528; Janssen / Legend), P-BCMA-101 (Poseida), PBCAR269A (Poseida), P-BCMA- Allol (Poseida), Allo-715 (Pfizer / Allogene), CT053 (Carsgen), Descartes-08 (Cartesian), PHE885 (Novartis), CTX120 (CRISPR Therapeutics); axicabtagene ciloleucel (YESCARTA®), tisagenlecleucel (KYMRIAH®), brexucabtagene autoleucel (TECARTUS®), or lisocabtagene maraleucel (BREYANZI®).

[0415] Engineered TCRs comprise TCRa and / or TCRP chains that have been isolated and cloned from T cell populations recognizing a particular target antigen. For example, TCRa and / or TCRP genes (z.e., TRAC and TRBC) can be cloned from T cell populations isolated from individuals with particular malignancies or T cell populations that have been isolated from humanized mice immunized with specific tumor antigens or tumor cells.Engineered TCRs recognize antigen through the same mechanisms as their endogenous counterparts (e.g., by recognition of their cognate antigen presented in the context of major histocompatibility complex (MHC) proteins expressed on the surface of a target cell). This antigen engagement stimulates endogenous signal transduction pathways leading to activation and proliferation of the TCR-engineered cells.

[0416] Engineered TCRs specific for tumor antigens are known in the art, for example WTl-specific TCRs (JTCR016, Juno Therapeutics; WTl-TCRc4, described in US Patent Application Publication No. 20160083449), MART-1 specific TCRs (including the DMF4T clone, described in Morgan et al., Science 314 (2006) 126-129); the DMF5T clone, described in Johnson et al., Blood 114 (2009) 535-546); and the ID3T clone, described in van den Berg et al., Mol. Ther. 23 (2015) 1541-1550), gp 100- specific TCRs (Johnson et al., Blood 114 (2009) 535-546), CEA-specific TCRs (Parkhurst et al., Mol Ther. 19 (2011) 620-626), NY- ESO and LAGE-1 specific TCRs (1G4T clone, described in Robbins et al., J Clin Oncol 26 (2011) 917-924; Robbins et al., Clin Cancer Res 21 (2015) 1019-1027; and Rapoport et al., Nature Medicine 21 (2015) 914-921), and MAGE-A3-specific TCRs (Morgan et al., J Immunother 36 (2013) 133-151) and Linette et al., Blood 122 (2013) 227-242). (See also, Debets et al., Seminars in Immunology 23 (2016) 10-21).IV. COMPOSITIONS AND KITS

[0417] Also provided are compositions and formulations containing engineered cells expressing a recombinant receptor produced by the methods provided herein. In some embodiments, the compositions and formulations contain cells, such as a composition or dose of cells, produced by methods described herein, such as in Section III. In some embodiments, the compositions and formulations are or contain output compositions of cells, and optionally instructions for use, for example, instructions for administering the engineered cells to a subject, such as by methods described herein, such as in Section V.

[0418] In some embodiments, the dose of cells comprising cells engineered with a recombinant antigen receptor, e.g. CAR or TCR, is provided as a composition or formulation, such as a pharmaceutical composition or formulation. Such compositions can be used in accord with the provided methods, and / or with the provided articles of manufacture or compositions, such as in the prevention or treatment of diseases, conditions, and disorders, or in detection, diagnostic, and prognostic methods.

[0419] The term “pharmaceutical formulation” refers to a preparation which is in such form as to permit the biological activity of an active ingredient contained therein to be effective, and which contains no additional components which are unacceptably toxic to a subject to which the formulation would be administered.

[0420] A “pharmaceutically acceptable carrier” refers to an ingredient in a pharmaceutical formulation, other than an active ingredient, which is nontoxic to a subject. A pharmaceutically acceptable carrier includes, but is not limited to, a buffer, excipient, stabilizer, or preservative.

[0421] In some aspects, the choice of carrier is determined in part by the particular cell or agent and / or by the method of administration. Accordingly, there are a variety of suitable formulations. For example, the pharmaceutical composition can contain preservatives. Suitable preservatives may include, for example, methylparaben, propylparaben, sodium benzoate, and benzalkonium chloride. In some aspects, a mixture of two or more preservatives is used. The preservative or mixtures thereof are typically present in an amount of about 0.0001% to about 2% by weight of the total composition. Carriers are described, e.g., by Remington’s Pharmaceutical Sciences 16th edition, Osol, A. Ed. (1980). Pharmaceutically acceptable carriers are generally nontoxic to recipients at the dosages and concentrations employed, and include, but are not limited to: buffers such as phosphate, citrate, and other organic acids; antioxidants including ascorbic acid and methionine; preservatives (such as octadecyldimethylbenzyl ammonium chloride; hexamethonium chloride; benzalkonium chloride; benzethonium chloride; phenol, butyl or benzyl alcohol; alkyl parabens such as methyl or propyl paraben; catechol; resorcinol; cyclohexanol; 3- pentanol; and m-cresol); low molecular weight (less than about 10 residues) polypeptides; prote...

Claims

1. WHAT IS CLAIMED:

1. A recombinant fusion protein comprising:(a) an IL-9 or a biologically active fragment thereof;(b) a modified IL-9 receptor (IL-9R) comprising an IL-9R extracellular domain, an IL-9R transmembrane domain, and an IL-9R intracellular domain, wherein one or both of the IL-9R extracellular domain and the IL-9R intracellular domain is a variant that comprises one or more mutations relative to the respective domain of a wild-type IL-9R; and(c) a peptide linker, wherein the IL-9 or the biologically active fragment thereof is connected to the modified IL-9R via the peptide linker.

2. A recombinant fusion protein comprising:(a) an IL-9 or a biologically active fragment thereof;(b) a modified IL-9 receptor (IL-9R) comprising an IL-9R extracellular domain, an IL-9R transmembrane domain, and a variant IL-9R intracellular domain comprising one or more mutations compared to a wild-type IL-9R intracellular domain, wherein the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways; and(c) a peptide linker, wherein the IL-9 or the biologically active fragment thereof is connected to the modified IL-9R via the peptide linker.

3. The recombinant fusion protein of claim 2, wherein the IL-9R extracellular domain is an extracellular domain of a wild-type IL-9R.

4. The recombinant fusion protein of claim 2 or claim 3, wherein the IL-9R extracellular domain comprises a sequence of amino acids that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 54 or is 100% identical to SEQ ID NO: 54.

5. The recombinant fusion protein of any of claims 2-4, wherein the IL-9R extracellular domain comprises the sequence of amino acids set forth in SEQ ID NO: 54.

6. The recombinant fusion protein of claim 1 or claim 2, wherein the IL-9R extracellular domain is a variant IL-9R extracellular domain comprising one or more mutations relative to the wild-type IL-9R extracellular domain.

7. The recombinant fusion protein of claim 1 or claim 6, wherein the variant IL- 9R extracellular domain is a truncated IL-9R extracellular domain and the one or more mutations is a deletion in which a contiguous sequence of amino acids is deleted from the N- terminus of wild-type IL-9R extracellular domain.

8. The recombinant fusion protein of claim 6 or claim 7, wherein the variant IL- 9R extracellular domain is a truncated IL-9R and the one or more mutations is a deletion in which a contiguous sequence of amino acids at the N-terminus is absent relative to wild-type IL-9R extracellular domain.

9. The recombinant fusion protein of any of claims 1 and 6-8, wherein the variant IL-9R extracellular domain lacks up to 115 contiguous amino acids from the N-terminus relative to wild-type IL-9R extracellular domain set forth in SEQ ID NO: 54.

10. The recombinant fusion protein of claim 9, wherein the variant IL-9R extracellular domain lacks from 20 to 108 contiguous amino acids from the N-terminus relative to wild-type IL-9R extracellular domain set forth in SEQ ID NO: 54.

11. The recombinant fusion protein of claim 9 or claim 10, wherein the variant IL- 9R extracellular domain lacks from 70 to 99 contiguous amino acids from the N-terminus relative to wild-type IL-9R extracellular domain set forth in SEQ ID NO: 54.

12. The recombinant fusion protein of any of claims 6-11, wherein the variant IL- 9R extracellular domain comprises the fibronectin-type III domain corresponding to amino acids 109-219 of SEQ ID NO: 54.

13. The recombinant fusion protein of any of claims 6-12, wherein the variant IL- 9R extracellular domain lacks a contiguous sequence of amino acids 1 to 99 of SEQ ID NO:54.

14. The recombinant fusion protein of any of claims 6-13, wherein the variant IL- 9R extracellular domain is set forth by a sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 105.

15. The recombinant fusion protein of any of claims 6-14, wherein the variant IL- 9R extracellular domain is set forth in SEQ ID NO: 105.

16. The recombinant fusion protein of any of claims 1-15, wherein the IL-9R transmembrane domain is a transmembrane domain of a wild-type IL-9R.

17. The recombinant fusion protein of any of claims 1-16, wherein the IL-9R transmembrane domain is a transmembrane domain comprising a sequence of amino acids that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 55 or is 100% identical to SEQ ID NO: 55.

18. The recombinant fusion protein of any of claims 1-17, wherein the IL-9R transmembrane domain is a transmembrane domain comprising the sequence of amino acids set forth in SEQ ID NO: 55.

19. A recombinant fusion protein comprising:(a) an IL-9 or a biologically active fragment thereof;(b) a modified IL-9 receptor (IL-9R) comprising an IL-9R extracellular domain set forth in SEQ ID NO: 105, an IL-9R transmembrane domain set forth in SEQ ID NO: 55 and an IL-9R intracellular domain; and(c) a peptide linker, wherein the IL-9 or the biologically active fragment thereof is connected to the modified IL-9R via the peptide linker.

20. The recombinant fusion protein of any of claims 1 and 6-19, wherein the IL- 9R intracellular domain is a wild-type IL-9R intracellular domain.

21. The recombinant fusion protein of any of claims 1-18 and 20, wherein the wild-type IL-9R is human IL-9R.

22. The recombinant fusion protein of any of claims 1-18, 20 and 21, wherein the wild-type IL-9R comprises the sequence as set forth in SEQ ID NO: 7.

23. The recombinant fusion protein of any of claims 20-22, wherein the IL-9R intracellular domain is an intracellular domain comprising a sequence of amino acids that is at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 56 or is 100% identical to SEQ ID NO: 56.

24. The recombinant fusion protein of any of claims 20-23, wherein the IL-9R intracellular domain is an intracellular domain comprising the sequence set forth in SEQ ID NO: 56.

25. The recombinant fusion of any of claims 1-18 and 20-24, wherein the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 153, 154, 155, 156, 157, 159, or 160.

26. The recombinant fusion of any of claims 1-18 and 20-25, wherein the recombinant fusion protein comprises the amino acid sequence set forth in any one of SEQ ID NOs: 153, 154, 155, 156, 157, 159, or 160.

27. The recombinant fusion of any of claims 1-18 and 20-24, wherein the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 161, 162, 163, 164, 165, 167, or 168.

28. The recombinant fusion of any of claims 1-18, 20-24, and 27, wherein the recombinant fusion protein comprises the amino acid sequence set forth in any one of SEQ ID NOs: 161, 162, 163, 164, 165, 167, or 168.

29. The recombinant fusion protein of any of claims 1 and 6-19, wherein the IL-9R intracellular domain is a variant IL-9R intracellular domain comprising one or more mutations relative to the wild-type IL-9R intracellular domain, wherein the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways.

30. A recombinant fusion protein comprising:(a) an IL-9 or a biologically active fragment thereof;(b) a modified IL-9 receptor (IL-9R) comprising an IL-9R extracellular domain and an IL-9R transmembrane domain set forth by amino acids 1-251 of SEQ ID NO: 7 and a variant IL-9R intracellular domain comprising one or more mutations compared to the wild-type IL-9R intracellular domain, wherein the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways; and(c) peptide linker, wherein the IL-9 or the biologically active fragment thereof is connected to the modified IL-9R via the peptide linker.

31. A recombinant fusion protein comprising:(a) an IL-9 or a biologically active fragment thereof;(b) a modified IL-9 receptor (IL-9R) comprising: (i) an IL-9R extracellular domain set forth by SEQ ID NO: 54; (ii)an IL-9R transmembrane domain set forth by SEQ ID NO: 55; and (iii) a variant IL-9R intracellular domain comprising one or more mutations compared to the wild-type IL-9R intracellular domain, wherein the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways; and(c) peptide linker, wherein the IL-9 or the biologically active fragment thereof is connected to the modified IL-9R via the peptide linker.

32. The recombinant fusion protein of any of claims 1-18 and 29-31, wherein the variant IL-9R intracellular domain is less than 260 amino acids in length.

33. The recombinant fusion protein of any of claims 1-18 and 29-32, wherein the variant IL-9R intracellular domain is about 100 to 260 amino acids in length.

34. The recombinant fusion protein of any of claims 1-18 and 29-33, wherein the variant IL-9R intracellular domain comprises a B0X1 motif and / or a B0X2 motif.

35. The recombinant fusion protein of any of claims 1-18 and 29-34, wherein the variant IL-9R intracellular domain comprises a B0X2 motif.

36. The recombinant fusion protein of any of claims 1-18 and 29-35, wherein the variant IL-9R intracellular domain is 230 amino acids in length.

37. The recombinant fusion protein of any of claims 1-18 and 29-36, wherein the variant IL-9R intracellular domain is a variant of a wild-type IL-9R intracellular domain and comprises one or more mutations compared to the wild-type IL-9R intracellular domain set forth in SEQ ID NO: 56.

38. The recombinant fusion protein of claim 37, wherein the one or more mutations comprises one or more amino acid insertions, deletions, and / or substitutions.

39. The recombinant fusion protein of claim 37 or claim 38, wherein the one or more mutations promote signaling through STAT1, STAT3, and / or STAT5 pathways .

40. The recombinant fusion protein of any of claims 1-18 and 29-39, wherein the variant IL-9R intracellular domain comprises an amino acid sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 56.

41. The recombinant fusion protein of any of claims 1-18 and 29-40, wherein the variant IL-9R intracellular domain comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 18-53.

42. The recombinant fusion protein of any of claims 1-18 and 29-41, wherein the variant IL-9R intracellular domain comprises an amino acid sequence of any one of SEQ ID NOs: 18-53.

43. The recombinant fusion protein of any of claims 1-18 and 29-42, wherein the variant IL-9R intracellular domain comprises the amino acid sequence of SEQ ID NO: 44.

44. The recombinant fusion protein of any of claims 1-18 and 29-43, wherein the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 57-92.

45. The recombinant fusion protein of any of claims 1-18 and 29-44, wherein the recombinant fusion protein comprises an amino acid sequence of any one of SEQ ID NOs: 57-92.

46. The recombinant fusion protein of any of claims 1-18 and 29-45, wherein the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 57, 60, 66, 67, 69, 71-75, 77, 80, 81, 82, 83, or 84.

47. The recombinant fusion protein of any of claims 1-18 and 29-46, wherein the recombinant fusion protein comprises an amino acid sequence of any one of SEQ ID NOs: 57, 60, 66, 67, 69, 71-75, 77, 80, 81, 82, 83, or 84.

48. The recombinant fusion protein of any of claims 1-18 and 29-43, wherein the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 110-145.

49. The recombinant fusion protein of any of claims 1-18, 29-43 and 48, wherein the recombinant fusion protein comprises an amino acid sequence of any one of SEQ ID NOs: 110-145.

50. The recombinant fusion protein of any of claims 1-18, 29-43, 48 and 49, wherein the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 110, 113, 119, 120, 122, 124-128, 130, 133, 134, 135, 136, or 137.

51. The recombinant fusion protein of any of claims 1-18, 29-43 and 48-50, wherein the recombinant fusion protein comprises an amino acid sequence of any one of SEQ ID NOs: 110, 113, 119, 120, 122, 124-128, 130, 133, 134, 135, 136, or 137.

52. The recombinant fusion protein of any of claims 1-18 and 29-51, wherein the recombinant fusion protein comprises the amino acid sequence of SEQ ID NO: 83 or SEQ ID NO: 136.

53. The recombinant fusion protein of any of claims 1-43, wherein the recombinant fusion protein comprises an amino acid sequence that is at least about 85% identical to SEQ ID NOs: 158 or SEQ ID NO: 166.

54. The recombinant fusion protein of any of claims 1-43 and 53, wherein the recombinant fusion protein comprises the amino acid sequence of SEQ ID NO: 158 or SEQ ID NO: 166.

55. The recombinant fusion protein of any one of claims 1-52, wherein the variant IL-9R intracellular domain comprises one or more mutations that are one or more amino acid deletions with reference to wild-type IL-9R intracellular domain (SEQ ID NO: 56).

56. The recombinant fusion protein of claim 55, wherein the intracellular domain is a truncated IL-9R intracellular domain and the one or more deletions is a truncation that deletes a contiguous sequence of amino acids from the C-terminus of wild-type IL-9R intracellular domain.

57. The recombinant fusion protein of any of claims 1-52, 55 and 56, wherein the variant IL-9R intracellular domain is a truncated IL-9R that lacks a contiguous sequence of amino acids at the C-terminus of wild-type IL-9R intracellular domain.

58. The recombinant fusion protein of claim 56 or claim 57, wherein the truncated IL-9R intracellular domain is truncated by between 62 and 99 contiguous amino acids from the C-terminus of wild-type IL-9R intracellular domain.

59. The recombinant fusion protein of any of claims 56-58, wherein the amino acid sequence of the truncated IL-9R is set forth by a sequence that is at least about 85%,86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to any one of SEQ ID NOs: 18-39 and 42-46.

60. The recombinant fusion protein of any of claims 56-59, wherein the amino acid sequence of the truncated IL-9R is set forth by the sequence of any one of SEQ ID Nos: 18-39 and 42-46.

61. The recombinant fusion protein of any of claims 56-60, wherein the truncated IL-9R intracellular domain lacks amino acids 132 to 230 of SEQ ID NO: 56 or lacks amino acids 134 to 230 of SEQ ID NO: 56.

62. The recombinant fusion protein of any of claims 56-61, wherein the amino acid sequence of the truncated IL-9R is set forth by a sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 43 or SEQ ID NO: 44.

63. The recombinant fusion protein of any of claims 56-62, wherein the amino acid sequence of the truncated IL-9R is set forth by the sequence of SEQ ID NO: 43 or SEQ ID NO: 44.

64. The recombinant fusion protein of any of claims 1-63, wherein the recombinant fusion protein comprises an amino acid sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 82 or SEQ ID NO: 83 or SEQ ID NO: 158.

65. The recombinant fusion protein of any of claims 1-64, wherein the recombinant fusion protein comprises the amino acid sequence of SEQ ID NO: 82 or SEQ ID NO: 83 or SEQ ID NO: 158.

66. The recombinant fusion protein of any of claims 1-63, wherein the recombinant fusion protein comprises an amino acid sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to SEQ ID NO: 135 or SEQ ID NO: 136 or SEQ ID NO: 166.

67. The recombinant fusion protein of any of claims 1-63 or 66, wherein the recombinant fusion protein comprises the amino acid sequence of SEQ ID NO: 135 or SEQ ID NO: 136 or SEQ ID NO: 166.

68. The recombinant fusion protein of any of claims 1-67, wherein the variant IL- 9R intracellular domain comprises one or more amino acid substitutions with reference positions of wild-type IL-9R intracellular domain (SEQ ID NO: 56).

69. The recombinant fusion protein of any of claims 1-68, wherein the variant IL- 9R intracellular domain comprises a STAT binding motif or a variant thereof.

70. The recombinant fusion protein of claim 69, wherein the STAT binding motif comprises a STAT1, STAT3, and / or STAT5 binding motif.

71. The recombinant fusion protein of claim 69 or claim 70, wherein the STAT binding motif comprises YLPQ (SEQ ID NO: 171).

72. The recombinant fusion protein of claim 69 or claim 70, wherein the STAT binding motif comprises a variant STAT binding motif.

73. The recombinant fusion protein of claim 69, 70, or 71, wherein the variant STAT binding motif comprises YRPQ (SEQ ID NO: 94).

74. The recombinant fusion protein of claim 69, 70, or 71, wherein the variant STAT binding motif comprises YLPL (SEQ ID NO: 95).

75. The recombinant fusion protein of any of claims 69, 70, or 71, wherein the variant STAT binding motif comprises YLKQ (SEQ ID NO: 96).

76. The recombinant fusion protein of any of claims 1-75, wherein the variant IL- 9R intracellular domain or variant thereof comprises an amino acid sequence that is at least about 85% identical to any one of SEQ ID NOs: 47-53.

77. The recombinant fusion protein of any of claims 1-76, wherein the variant IL- 9R intracellular domain comprises an amino acid sequence of any one of SEQ ID NOs: 47- 53.

78. The recombinant fusion protein of any of claims 1-77, wherein the recombinant fusion protein comprises an amino acid sequence that is at least about 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical to any one of SEQ ID NOs: 86-92 or 139-145.

79. The recombinant fusion protein of any of claims 1-78, wherein the recombinant fusion protein comprises the amino acid sequence of any one of SEQ ID NOs: 86-92 or 139-145.

80. The recombinant fusion protein of any of claims 1-79, wherein the IL-9 or the biologically active fragment thereof is wild-type IL-9.

81. The recombinant fusion protein of claim 80, wherein the wild-type IL-9 is human IL- 9.

82. The recombinant fusion protein of any of claims 1-81, wherein the IL-9 comprises an amino acid sequence at least about 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to the sequence as set forth in SEQ ID NO: 8.

83. The recombinant fusion protein of any of claims 1-82, wherein the IL-9 comprises the amino acid sequence set forth in SEQ ID NO: 8.

84. The recombinant fusion protein of any of claims 1-81, wherein the IL-9 comprises an amino acid sequence at least about 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to the sequence as set forth in SEQ ID NO: 185.

85. The recombinant fusion protein of any of claims 1-81 and 84, wherein the IL-9 comprises the amino acid sequence set forth in SEQ ID NO: 185.

86. The recombinant fusion protein of any of claims 1-85, wherein the IL-9 is encoded by a nucleic acid sequence that is at least about 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to the nucleic acid sequence as set forth in SEQ ID NO: 6.

87. The recombinant fusion protein of any of claims 1-86, wherein the IL-9 comprises the nucleic acid sequence set forth in SEQ ID NO: 6.

88. The recombinant fusion protein of any of claims 1-87, wherein the linker is a peptide linker.

89. The recombinant fusion protein of any of claims 1-88, wherein the linker is a flexible linker.

90. The recombinant fusion protein of any of claims 1-89, wherein the linker is 5 to 30 amino acids in length.

91. The recombinant fusion protein of any of claims 1-90, wherein the linker is 12 to 26 amino acids in length.

92. The recombinant fusion protein of any of claims 1-91, wherein the linker is 15 to 20 amino acids in length.

93. The recombinant fusion protein of any of claims 1-92, wherein the linker is a GS linker.

94. The recombinant fusion protein of any of claims 1-93, wherein the linker comprises the sequence GS, GGS, GGGGS (SEQ ID NO: 10), GGGGGS (SEQ ID NO: 11), or combinations thereof.

95. The recombinant fusion protein of any of claims 1-94, wherein the linker comprises (GGS)n, wherein n is 1 to 10.

96. The recombinant fusion protein of any of claims 1-95, wherein the linker comprises (GGGGS)n (SEQ ID NO: 12), wherein n is 1 to 6.

97. The recombinant fusion protein of any of claims 1-96, wherein the linker comprises (GGGGGS)n (SEQ ID NO: 13), wherein n is 1 to 5.

98. The recombinant fusion protein of any of claims 1-97, wherein the linker is (GGGGS)2 (SEQ ID NO: 106).

99. The recombinant fusion protein of any of claims 1-97, wherein the linker is (GGGGS)3 (SEQ ID NO: 14).

100. The recombinant fusion protein of any of claims 1-97, wherein the linker is (GGGGS)4 (SEQ ID NO: 107).

101. The recombinant fusion protein of any of claims 1-97, wherein the linker is (GGGGS)5 (SEQ ID NO: 15).

102. A recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 136.

103. The recombinant fusion protein of claim 102, wherein the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQ ID NO: 136.

104. The recombinant fusion protein of claim 102 or claim 103, wherein the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 136.

105. A recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 162.

106. The recombinant fusion protein of claim 105, wherein the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQ ID NO: 162.

107. The recombinant fusion protein of claim 105 or claim 106, wherein the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 162.

108. A recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 164.

109. The recombinant fusion protein of claim 108, wherein the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQ ID NO: 164.

110. The recombinant fusion protein of claim 108 or claim 109, wherein the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 164.

111. A recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 166.

112. The recombinant fusion protein of claim 111, wherein the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQ ID NO: 166.

113. The recombinant fusion protein of claim 111 or 112, wherein the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 166.

114. A recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 167.

115. The recombinant fusion protein of claim 114, wherein the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQ ID NO: 167.

116. The recombinant fusion protein of claim 114 or claim 115, wherein the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 167.

117. A recombinant fusion protein comprising an amino acid sequence that has at least 85% sequence identity to SEQ ID NO: 168.

118. The recombinant fusion protein of claim 117, wherein the recombinant fusion protein has at least 90%, 92%, 95% or 97% sequence identity to SEQ ID NO: 168.

119. The recombinant fusion protein of claim 117 or claim 118, wherein the recombinant fusion protein comprises the sequence set forth in SEQ ID NO: 168.

120. The recombinant fusion protein of any one of claims 1-119, wherein the recombinant fusion protein comprises an N-terminal signal peptide.

121. The recombinant fusion protein of claim 120, wherein the signal peptide is MLLAMVLTSALLLCSMAG (SEQ ID NO: 108).

122. The recombinant fusion protein of any of claims 1-121, wherein the recombinant fusion protein is capable of associating with the common receptor gamma chain (common yC) when the recombinant fusion protein is engineered into a cell expressing common yC.

123. The recombinant fusion protein of claim 122, wherein the cell is a lymphocyte.

124. The recombinant fusion protein of claim 122 or claim 123, wherein the cell is a T cell.

125. The recombinant fusion protein of any of claims 1-124, wherein the recombinant fusion protein constitutively induces signaling through STAT1, STAT3, and / or STAT5 pathways in the absence of added exogenous IL-9.

126. A nucleic acid sequence encoding a recombinant fusion protein of any of claims 1-125.

127. A polynucleotide construct comprising in 5’ to 3’ order (a) a tethered IL-9 / IL- 9R transgene sequence comprising a nucleotide sequence encoding a recombinant fusion protein of any of claims 1-125 and (b) at least one additional transgene sequence, wherein the tethered IL-9 / IL-9R transgene sequence and the at least one additional transgene sequence are separated by a multicistronic linker sequence.

128. A polynucleotide construct comprising in 5’ to 3’ order (a) at least one additional transgene sequence and (b) a tethered IL-9 / IL-9R transgene sequence comprising a nucleotide sequence encoding a recombinant fusion protein of any of claims 1-125, wherein the at least one additional transgene sequence and the tethered IL-9 / IL-9R transgene sequence are separated by multicistronic linker sequence.

129. The polynucleotide construct of claim 127 or claim 128, wherein the multicistronic linker sequence is a nucleotide sequence encoding a cleavage site sequence.

130. The polynucleotide construct of any of claims 127-129, wherein the multicistronic linker is a P2A linker.

131. The polynucleotide construct of any of claims 127-130, wherein the multicistronic linker sequence is a nucleotide sequence with at least 85% identity to SEQ ID NO: 99.

132. The polynucleotide construct of any of claims 127-131, wherein the multicistronic linker sequence is a nucleotide sequence set forth in SEQ ID NO: 99.

133. The polynucleotide construct of any of claims 127-132, wherein the multicistronic linker sequence is a nucleotide sequence which encodes an amino acid with at least 85% identity to SEQ ID NO: 98.

134. The polynucleotide construct of any of claims 127-133, wherein the tethered IL-9 / IL-9R transgene sequence and the at least one additional transgene sequence are controlled by the same or different promoter.

135. The polynucleotide construct of any of claims 127-134, wherein the tethered IL-9 / IL-9R transgene sequence and the at least one additional transgene are controlled by the same promoter.

136. The polynucleotide construct of claim 134 or claim 135, wherein the promoter is an EF- la promoter.

137. The polynucleotide construct of any of claims 127-136, wherein the at least one additional transgene sequence encodes an engineered receptor.

138. The polynucleotide construct of claim 137, wherein the engineered receptor is a chimeric antigen receptor (CAR).

139. A vector, comprising the nucleic acid sequence of claim 126.

140. A vector, comprising the polynucleotide of any one of claims 127-138.

141. The vector of claim 139 or claim 140, wherein the vector is a viral vector.

142. The vector of claim 141, wherein the viral vector is a lentiviral vector.

143. A method of engineering cells, the method comprising introducing the nucleic acid of claim 126 to a cell.

144. A method of engineering cells, the method comprising introducing the polynucleotide construct of any of claims 127-138 to a cell.

145. A method of engineering cells, the method comprising introducing the vector of any of claims 139-142 to a cell.

146. The method of any of claims 143-145, wherein the cell is an immune cell.

147. The method of any of claims 143-146, wherein the cell is a lymphocyte.

148. The method of claim 147, wherein the lymphocyte is a T lymphocyte.

149. The method of claim 148, wherein the T lymphocyte is a CD8+ cytotoxic T lymphocyte.

150. The method of claim 147, wherein the lymphocyte is a Natural Killer (NK) cell.

151. The method of any of claims 143-150, wherein the cell is a primary cell from a subject.

152. The method of claim 151, wherein the subject is human.

153. The method of any of claims 143-151, wherein the cell is a derived from a stem cell, optionally an induced pluripotent cell.

154. The method of any of claims 143-153, wherein the cell is a hypoimmune cell for allogeneic cell therapy. 16155. The method of engineering cells of any of claims 143-154, comprising prior to the introducing, stimulating the cells with a stimulatory reagent.

156. The method of engineering cells of any of claims 143-155, further comprising expanding the cells after the introducing.

157. A cell comprising the recombinant fusion protein of any one of claims 1-125.

158. A cell comprising the nucleic acid of claim 126.

159. A cell comprising the polynucleotide construct of any of claims 127-138.

160. A cell comprising the vector of any of claims 139-142.

161. The cell of any of claims 157-160, wherein the cell is an immune cell.

162. The cell of any of claims 157-161, wherein the cell is a lymphocyte.

163. The cell of claim 162, wherein the lymphocyte is a T lymphocyte.

164. The cell of claim 163, wherein the T lymphocyte is a CD8+ cytotoxic T lymphocyte.

165. The cell of claim 163, wherein the lymphocyte is a Natural Killer (NK) cell.

166. The cell of any of claims 157-165, wherein the cell is a primary cell from a subject.

167. The cell of claim 166, wherein the subject is human.

168. The cell of any of claims 157-165, wherein the cell is a derived from a stem cell, optionally an induced pluripotent cell.

169. The cell of any of claims 157-168, wherein the cell is a hypoimmune cell for allogeneic cell therapy.

170. The cell of claim 157-169, wherein the recombinant fusion protein is a transmembrane protein expressed on the surface of the cell, wherein the IL-9 is exposed on the outside of the cell.

171. The cell of any of claims 157-170, wherein the cell further comprises an engineered receptor.

172. The cell of claim 171, wherein the engineered receptor is a chimeric antigen receptor (CAR) or a T cell receptor (TCR).

173. The cell of claim 171 or claim 172, wherein the engineered receptor is a CAR.

174. The cell of any of claims 157-173, wherein the cell exhibits an increase in one or more of STAT1, STAT3, and / or STAT5 activation as compared to a similar cell that does not comprise the recombinant fusion protein.

175. The cell of any of claims 157-174, wherein the cell exhibits an increase in STAT1 activation as compared to a similar cell that does not comprise the recombinant fusion protein.

176. The cell of any of claims 157-175, wherein the cell exhibits an increase in STAT3 activation as compared to a similar cell that does not comprise the recombinant fusion protein.

177. The cell of any of claims 157-176, wherein the cell exhibits an increase in STAT5 activation as compared to a similar cell that does not comprise the recombinant fusion protein.

178. The cell of any of claims 157-177, wherein the cell exhibits an increase in CD45RA expression as compared to a similar cell that does not comprise the recombinant fusion protein.

179. The cell of any of claims 157-178, wherein the cell exhibits an increase in CD27 expression as compared to a similar cell that does not comprise the recombinant fusion protein.

180. The cell of any of claims 157-179, wherein the cell exhibits an increase in CD45RA expression and CD27 expression as compared to a similar cell that does not comprise the recombinant fusion protein.

181. The cell of any of claims 157-180, where the cell exhibits a decrease in CD39 expression as compared to a similar cell that does not comprise the recombinant fusion protein.

182. The cell of any of claims 157-181, wherein the cell exhibits an increase in interferon gamma (IFN-y), tumor necrosis factor alpha (TNFa), IL-2, and / or IL- 10 secretion as compared to a similar cell that does not comprise the recombinant fusion protein.

183. A population of cells comprising a plurality of the cells of any of claims 157- 182.

184. A composition, comprising the population of cells of 183.

185. The composition of claim 184, further comprising a pharmaceutically acceptable.

186. A method of enhancing cell function comprising culturing a cell of any of claims 157-182 or a population of cells of any of claim 183, wherein the IL-9 of the recombinant fusion protein constitutively induces intracellular signaling by the modified IL- 9R.

187. The method of claim 186, wherein the intracellular signaling phosphorylates one or more of STAT1, STAT3, or STAT5.

188. The method of claim 186 or claim 187, wherein the intracellular signaling phosphorylates each of STAT1, STAT3, or STAT5.

189. The method of any of claims 186-188, wherein the cell or population of cells are T cells and the constitutive signaling promotes a stem-like memory T cell phenotype or naive-like T cell phenotype.

190. The method of any of claims 186-188, wherein the constitutive signaling enhances the percentage of cells of the population of cells that have a stem- like memory T cell phenotype or naive-like phenotype.

191. The method of any of claims 186-190, wherein the constitutive signaling enhances the percentage of cells that are positive for CD45RA+ and CD27+.

192. The method of any of claims 186-191, wherein the cell or population of cells are T cells and the constitutive signaling promotes T cell proliferation.

193. The method of any of claims 186-192, wherein the cell or population of cells are T cells and the constitutive signaling promotes IFN-gamma production.

194. The method of any of claims 186-193, wherein the culturing further comprising contacting the cell or population of cells with a cell- stimulating agent.

195. The method of claim 194, wherein the cell or population of cells comprise an engineered receptor directed against a target antigen and the cell- stimulating agent comprises the target antigen.

196. The method of claim 195, wherein the cell- stimulating agent is a target antigen-expressing cell.

197. The method of any of claims 186-196 that is carried out in vitro or ex vivo.

198. The method of any of claims 186-197 that is carried out in vivo in a subject, wherein the cell or population of cells are administered to the subject.

199. The method of claim 198, wherein the subject has a disease or a condition and the method treats the disease or the condition in the subject.

200. A method of treating a disease or a condition in a subject, comprising administering to the subject a dose of cells of the composition of claim 184 or claim 185.

201. The method of claims 199 or claim 200, wherein the disease or the condition is a cancer.

202. The method of claim 201, wherein the engineered cell of the pharmaceutical composition expresses an engineered receptor that binds to an antigen expressed on a cell of the cancer.

203. The method of any of claims 195-199 or claim 202, wherein the engineered receptor is a chimeric antigen receptor (CAR).

204. The method of claim 202, wherein the engineered receptor is a T cell receptor.

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