Patent Application
20230364138
Glioblastoma (GBM) ranks as one of the most lethal of human cancers with current therapy offering only palliation. Standard-of-care therapy consisting of maximal surgical resection followed by combined radiation and chemotherapy extends median survival by less than 3 months. The activation of anti-tumor immune responses may provide new opportunities to augment tumor control. As such, immunotherapies have been extensively investigated with positive results in preclinical studies, yet broad antitumor efficacy has not occurred in patients (1). The adoptive transfer of chimeric antigen receptor (CAR) engineered T cells has shown promising clinical activity in a subset of cancers, particularly B cell malignancies (2,3). To target GBM, CAR T cells have been engineered to recognize selected tumor antigens and have demonstrated cytolytic activity against GBM cells, including GBM stem cells (GSCs) (4-6). In patients with GBM, CAR T cell therapies have shown early evidence of activity, clinical feasibility, and safety (7-10). However, the overall outcomes of CAR T cell treatment remain unsatisfactory, prompting efforts to enhance the antitumor potency of GBM-targeting CAR T cells (11,12). The functional potentiation of CAR T cells, while attractive due to the modifiable nature of these cells, requires a comprehensive understanding of the molecular events regulating CAR T cell activation, exhaustion and tumor-induced immune suppression (11,13).
Aside from CAR recognition of tumor antigens, the complicated and dynamic interaction between CAR T cells and their target tumor cells remains poorly characterized. Thus, there is a need for new strategies to further enhance CAR T cell potency.
Gene editing using the clustered randomly interspersed short palindromic repeats (CRISPR)-Cas9 is a promising approach to enhance cancer immunotherapy (14). Directed CRISPR-Cas9 gene knockout of checkpoint and other immune-regulatory receptors have shown utility for adoptive T cell therapy (15,16); however, this approach has focused on a limited set of known pathways. By contrast, large CRISPR-knockout screens are an effective platform for unbiased target discovery and have been successfully used to identify genes in tumor cells which when deleted synergize with various types of immunotherapeutics (17-19). CRISPR screens in T cells identified modulators of TCR activation in response to stimulation with CD3/CD28 agonistic beads, viruses, or tumor cells (20-22). Although CAR constructs are synthetic TCR-like receptors incorporating CD3ζ and costimulatory domains, the molecular events are not identical between TCR and CAR T cell activation signaling pathways (23).
Described below are genetically modified (edited) T cells having a disruption in one or more specific genes. The engineered T cells are useful for expressing a chimeric antigen receptor (CAR) targeted to a cell surface protein (e.g., a CAR targeted to IL13Ra2, which is highly expressed on glioblastoma cells). The engineered T cells having one or more or the gene disruptions described herein can be used to create CAR T cells having increased efficacy compared to otherwise identical CART T cells that lack the specific gene disruption.
The edited cells have reduced expression of one or more of: Transducin-Like Enhancer of Split 4 (TLE4), Transmembrane Protein 184B (MEM184B), a Eukaryotic Translation Initiation Factor 5A-1 (EIF5A) or Ikaros Family Zinc Finger Protein 2 (IKZF2). Editing of these genes to reduce expression (e.g., knockdown of expression or knockout of expression) can be achieved by generating of indels that result in disruption of a target gene, for example, reduction or elimination of gene expression and or function.
Described herein is a population of engineered human T cells, wherein the engineered human T cells comprise: a disrupted Transducin-Like Enhancer of Split 4 (TLE4) gene, a disrupted Transmembrane Protein 184B (MEM184B) gene, a disrupted Eukaryotic Translation Initiation Factor 5A-1 (EIF5A) gene or a disrupted Ikaros Family Zinc Finger Protein 2 (IKZF2) gene.
In various embodiments: the disrupted TLE4 gene comprises an insertion of at least 10 contiguous nucleotides into SEQ ID NO: D1; the disrupted MEM184B gene comprises an insertion of at least 10 contiguous nucleotides into SEQ ID NO: D2; the disrupted EIF5A gene comprises an insertion of at least 10 contiguous nucleotides into SEQ ID NO: D3; the disrupted IKZF2 gene comprises a deletion of at least 10 contiguous nucleotides of SEQ ID NO: D4; the disrupted TLE4 gene comprises a deletion of at least 10 contiguous nucleotides of SEQ ID NO: D1; the disrupted MEM184B gene comprises a deletion of at least 10 contiguous nucleotides of SEQ ID NO: D2; the disrupted EIF5A gene comprises a deletion of at least 10 contiguous nucleotides of SEQ ID NO: D3;m the disrupted IKZF2 gene comprises a deletion of at least 10 contiguous nucleotides of SEQ ID NO: D4; at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% of the engineered T cells do not express a detectable level of TLE4; at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% of the engineered T cells do not express a detectable level of MEM184B; at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% of the engineered T cells do not express a detectable level of EIF5A; and at least 75%, at least 80%, at least 85%, at least 90%, or at least 95% of the engineered T cells do not express a detectable level of KZF2.
Also disclosed is a population of engineered T cells wherein the disrupted gene is disrupted by a nucleic acid encoding a chimeric antigen receptor.
In some case, at least 30% of the T cells comprises a nucleic acid molecule comprising a nucleotide sequence encoding a chimeric antigen receptor (CAR) wherein the chimeric antigen receptor comprises a targeting domain, a spacer, a transmembrane domain, a co-stimulatory domain, and a CD3 (signaling domain. In various cases: the targeting domain comprises a scFv that selectively binds a tumor cell antigen; the targeting domain comprises a ligand for a cell surface receptor; the nucleic acid molecule encoding the CAR is an mRNA.
Also described is a method for producing an engineered T cell, the method comprising: (a) delivering to a T cell: a RNA-guided nuclease, a gRNA targeting a TLE4 gene, a EMM1848 gene, or a KZF2 gene, a vector comprising a donor template that comprises a nucleic acid encoding a CAR; and (b) producing an engineered T cell suitable for allogeneic transplantation.
In some cases, the editing can include Insertion of a nucleic acid encoding a CAR into the disrupted genomic loci by using guide RNA/Cas9 to induce a double stranded break that is repaired by HDR using a donor template with homology around the cut site. Thus, the methods described herein can be used to knock-in a nucleic acid encoding a chimeric antigen receptor (CAR) in or near a locus of a target gene by permanently deleting at least a portion of the target gene and inserting a nucleic acid encoding the CAR. The CARs described herein include a targeting domain, a spacer, a transmembrane domain, a co-stimulatory domain, and a CD3 (signaling domain.
Provided herein are methods to DNA double stranded breaks (DBSs) that induce small insertions or deletions in a target gene resulting in the disruption (e.g., reduction or elimination of gene expression and/or function) of the target gene. Also described are methods to create and/or permanently delete within or near the target gene and to insert a nucleic acid construct encoding a CAR construct in the gene by inducing a double stranded break with Cas9 and a sgRNA in a target sequence (or a pair of double stranded breaks using two appropriate sgRNAs), and to provide a donor DNA template to induce Homology-Directed Repair (HDR). In some embodiments, the donor DNA template can be a short single stranded oligonucleotide, a short double stranded oligonucleotide, a long single or double stranded DNA molecule. These methods use gRNAs and donor DNA molecules for each target. In some embodiments, the donor DNA is single or double stranded DNA having homologous arms to the corresponding region. In some embodiments, the homologous arms are directed to the nuclease-targeted region of a gene selected from the group consisting of: Transducin-Like Enhancer of Split 4 (TLE4), Transmembrane Protein 184B (MEM184B), a Eukaryotic Translation Initiation Factor 5A-1 (EIF5A) or Ikaros Family Zinc Finger Protein 2 (IKZF2).
Provided herein are cellular methods (e.g., ex vivo or in vivo) methods for using genome engineering tools to create permanent changes to the genome by: 1) creating DSBs to induce small insertions, deletions or mutations within or near a target gene, 2) deleting within or near the target gene or other DNA sequences that encode regulatory elements of the target gene and inserting, by HDR, a nucleic acid encoding a knock-in CAR construct within or near the target gene or other DNA sequences that encode regulatory elements of the target gene, or 3) creating DSBs within or near the target gene and inserting a nucleic acid construct within or near the target gene by HDR. Such methods use endonucleases, such as CRISPR-associated (Cas9, Cpfl and the like) nucleases, to permanently delete one or more or exons or portions of exons of the target genes.
A very large number of CAR have are known. The engineered T cells described herein can be used to express any selected CAR.
The targeting region comprises a ligand for a cell-surface receptor or a scFv targeted to a cell surface molecule.
In the case of a CAR targeted to IL13Ra, the targeting region can comprises or consist of the amino acid sequence GPVPPSTALRYLIEELVNITQNQKAPLCNGSMVWSINLTAGMYCAALESLINVSGCS AIEKTQRMLSGFCPHKVSAGQFSSLHVRDTKIEVAQFVKDLLLHLKKLFREGRFNF (SEQ ID NO:1), which is a variant of human IL13. A suitable CAR targeted to IL13Ra is described in U.S. Pat. No. 9,914,909.
The CAR or polypeptide described herein can include a spacer located between the CD45 targeting domain (i.e., a CD45 targeted ScFv or variant thereof) and the transmembrane domain. A variety of different spacers can be used. Some of them include at least portion of a human Fc region, for example a hinge portion of a human Fc region or a CH3 domain or variants thereof. Table 1 below provides various spacers that can be used in the CARs described herein.
Some spacer regions include all or part of an immunoglobulin (e.g., IgG1, IgG2, IgG3, IgG4) hinge region, i.e., the sequence that falls between the CH1 and CH2 domains of an immunoglobulin, e.g., an IgG4 Fc hinge or a CD8 hinge. Some spacer regions include an immunoglobulin CH3 domain (called CH3 or ACH2) or both a CH3 domain and a CH2 domain. The immunoglobulin derived sequences can include one or more amino acid modifications, for example, 1, 2, 3, 4 or 5 substitutions, e.g., substitutions that reduce off-target binding.
The hinge/linker region can also comprise a IgG4 hinge region having the sequence ESKYGPPCPSCP (SEQ ID NO:4) or ESKYGPPCPPCP (SEQ ID NO:3). The hinge/linger region can also comprise the sequence ESKYGPPCPPCP (SEQ ID NO:3) followed by the linker sequence GGGSSGGGSG (SEQ ID NO:2) followed by IgG4 CH3 sequence GQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTP PVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLSLGK (SEQ ID NO:12). Thus, the entire linker/spacer region can comprise the sequence: ESKYGPPCPPCPGGGSSGGGSGGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGF YPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSV MHEALHNHYTQKSLSLSLGK (SEQ ID NO:11). In some cases, the spacer has 1, 2, 3, 4, or 5 single amino acid changes (e.g., conservative changes) compared to SEQ ID NO:11. In some cases, the IgG4 Fc hinge/linker region that is mutated at two positions (L235E; N297Q) in a manner that reduces binding by Fc receptors (FcRs).
A variety of transmembrane domains can be used in the CAR. Table 2 includes examples of suitable transmembrane domains. Where a spacer region is present, the transmembrane domain (TM) is located carboxy terminal to the spacer region.
The costimulatory domain can be any domain that is suitable for use with a CD3ζ signaling domain. In some cases the co-signaling domain is a 4-1 BB co-signaling domain that includes a sequence that is at least 90%, at least 95%, at least 98% identical to or identical to: KRGRKKLLYIFKQPFMRPVQTTQEEDGCSCRFPEEEEGGCEL (SEQ ID NO:24). In some cases, the 4-1 BB co-signaling domain has 1, 2, 3, 4 of 5 amino acid changes (preferably conservative) compared to SEQ ID NO:24.
The costimulatory domain(s) are located between the transmembrane domain and the CD3ζ signaling domain. Table 3 includes examples of suitable costimulatory domains together with the sequence of the CD3ζ signaling domain.
In various embodiments: the costimulatory domain is selected from the group consisting of: a costimulatory domain depicted in Table 3 or a variant thereof having 1-5 (e.g., 1 or 2) amino acid modifications, a CD28 costimulatory domain or a variant thereof having 1-5 (e.g., 1 or 2) amino acid modifications, a 4-1 BB costimulatory domain or a variant thereof having 1-5 (e.g., 1 or 2) amino acid modifications and an OX40 costimulatory domain or a variant thereof having 1-5 (e.g., 1 or 2) amino acid modifications. In certain embodiments, a 4-1 BB costimulatory domain or a variant thereof having 1-5 (e.g., 1 or 2) amino acid modifications in present. In some embodiments there are two costimulatory domains, for example a CD28 co-stimulatory domain or a variant thereof having 1-5 (e.g., 1 or 2) amino acid modifications (e.g., substitutions) and a 4-1 BB co-stimulatory domain or a variant thereof having 1-5 (e.g., 1 or 2) amino acid modifications (e.g., substitutions). In various embodiments the 1-5 (e.g., 1 or 2) amino acid modification are substitutions. The costimulatory domain is amino terminal to the CD3ζ signaling domain and a short linker consisting of 2-10, e.g., 3 amino acids (e.g., GGG) is can be positioned between the costimulatory domain and the CD3ζ signaling domain.
In some cases, the CAR can include two co-stimulatory domains, e.g., CD28 and 41 BB (in either order); OX40 and 41 BB (in either order); or CD28 and OX40 (in either order). Where two co-stimulatory domains are present, a spacer of 4-20 amino acids can be located between the two co-stimulatory domains.
Other co-stimulatory domains that can be used include: CD27, CD30, CD40, PD-1, ICOS, CD2, CD7, LIGHT, NKG2C, B7-H3, CDS, ICAM-1, GITR, BAFFR, HVEM (LIGHTR), SLAMF7, NKp80 (KLRF1), CD160, CD19. CD4, CD8a, CD8, IL2RP, IL2Ry, IL7Ra, ITGA4, VLA1, CD49a, ITGA4, IA4, CD49D, ITGA6, VLA-6, CD49f, ITGAD, CD11d, ITGAE. CD103, ITGAL, CDIIa, LFA-1, ITGAM, CDI Ib, ITGAX, CDI Ic. ITGB1, CD29, ITGB2, CD18, LFA-1, ITGB7, TNFR2, TRANCE/RANKL, DNAM1 (CD226), SLAMF4 (CD244, 2B4), CD84, CD96 (Tactile), CEACAM1, CRTAM, Ly9 (CD229). CD160 (BY55), PSGL1, CD100 (SEMA4D), CD69, SLAMF6 (NTB-A, LyI08), SLAM (SLAMF1, CD150, IPO-3), BLAME (SLAMF8), SELPLG (CD162), LTBR, LAT, GADS, SLP-76, PAG/Cbp, NKp44, NKp30, NKp46, and NKG2D.
The CD3ζ Signaling domain can be any domain that is suitable for use with a CD3ζ signaling domain. In some cases, the CD3ζ signaling domain includes a sequence that is at least 90%, at least 95%, at least 98% identical to or identical to: RVKFSRSADAPAYQQGQNQLYNELNLGRREEYDVLDKRRGRDPEMGGKPRRKNP QEGLYNELQKDKMAEAYSEIGMKGERRRGKGHDGLYQGLSTATKDTYDALHMQA LPPR (SEQ ID NO:21). In some cases, the CD3ζ signaling has 1, 2, 3, 4 of 5 amino acid changes (preferably conservative) compared to SEQ ID NO:21.
The CD3ζ signaling domain can be followed by a ribosomal skip sequence (e.g., LEGGGEGRGSLLTCGDVEENPGPR; SEQ ID NO:27) and a truncated EGFR having a sequence that is at least 90%, at least 95%, at least 98% identical to or identical to: LVTSLLLCELPHPAFLLIPRKVCNGIGIGEFKDSLSINATNIKHFKNCTSISGDLHILPV AFRGDSFTHTPPLDPQELDILKTVKEITGFLLIQAWPENRTDLHAFENLEIIRGRTKQ HGQFSLAVVSLNITSLGLRSLKEISDGDVIISGNKNLCYANTINWKKLFGTSGQKTKII SNRGENSCKATGQVCHALCSPEGCWGPEPRDCVSCRNVSRGRECVDKCNLLEG EPREFVENSECIQCHPECLPQAMNITCTGRGPDNCIQCAHYIDGPHCVKTCPAGVM GENNTLVWKYADAGHVCHLCHPNCTYGCTGPGLEGCPTNGPKIPSIATGMVGALL LLLWALGIGLFM (SEQ ID NO:28). In some cases, the truncated EGFR has 1, 2, 3, 4 of 5 amino acid changes (preferably conservative) compared to SEQ ID NO:28. Alternatively the CD3ζ signaling domain can be followed by a ribosomal skip sequence (e.g., LEGGGEGRGSLLTCGDVEENPGPR; SEQ ID NO:27) and a truncated CD19R (also called CD19t) having a sequence that is at least 90%, at least 95%, at least 98% identical to or identical to:
An amino acid modification refers to an amino acid substitution, insertion, and/or deletion in a protein or peptide sequence. An “amino acid substitution” or “substitution” refers to replacement of an amino acid at a particular position in a parent peptide or protein sequence with another amino acid. A substitution can be made to change an amino acid in the resulting protein in a non-conservative manner (i.e., by changing the codon from an amino acid belonging to a grouping of amino acids having a particular size or characteristic to an amino acid belonging to another grouping) or in a conservative manner (i.e., by changing the codon from an amino acid belonging to a grouping of amino acids having a particular size or characteristic to an amino acid belonging to the same grouping). Such a conservative change generally leads to less change in the structure and function of the resulting protein. The following are examples of various groupings of amino acids: 1) Amino acids with nonpolar R groups: Alanine, Valine, Leucine, Isoleucine, Proline, Phenylalanine, Tryptophan, Methionine; 2) Amino acids with uncharged polar R groups: Glycine, Serine, Threonine, Cysteine, Tyrosine, Asparagine, Glutamine; 3) Amino acids with charged polar R groups (negatively charged at pH 6.0): Aspartic acid, Glutamic acid; 4) Basic amino acids (positively charged at pH 6.0): Lysine, Arginine, Histidine (at pH 6.0). Another grouping may be those amino acids with phenyl groups: Phenylalanine, Tryptophan, and Tyrosine.
In some cases, the CAR can be produced using a vector in which the CAR open reading frame is followed by a T2A ribosome skip sequence and a truncated EGFR (EGFRt), which lacks the cytoplasmic signaling tail. In this arrangement, co-expression of EGFRt provides an inert, non-immunogenic surface marker that allows for accurate measurement of gene modified cells, and enables positive selection of gene-modified cells, as well as efficient cell tracking of the therapeutic T cells in vivo following adoptive transfer. Efficiently controlling proliferation to avoid cytokine storm and off-target toxicity is an important hurdle for the success of T cell immunotherapy. The EGFRt incorporated in the CAR lentiviral vector can act as suicide gene to ablate the CAR+ T cells in cases of treatment-related toxicity.
The CAR described herein can be produced by any means known in the art, though preferably it is produced using recombinant DNA techniques. Nucleic acids encoding the several regions of the chimeric receptor can be prepared and assembled into a complete coding sequence by standard techniques of molecular cloning known in the art (genomic library screening, overlapping PCR, primer-assisted ligation, site-directed mutagenesis, etc.) as is convenient. The resulting coding region is preferably inserted into an expression vector and used to transform a suitable expression host cell line, preferably a T lymphocyte, and most preferably an autologous T lymphocyte.
Various T cell subsets isolated from the patient can be transduced with a vector for CAR or polypeptide expression. Central memory T cells are one useful T cell subset. Central memory T cell can be isolated from peripheral blood mononuclear cells (PBMC) by selecting for CD45RO+/CD62L+ cells, using, for example, the CliniMACS® device to immunomagnetically select cells expressing the desired receptors. The cells enriched for central memory T cells can be activated with anti-CD3/CD28, transduced with, for example, a lentiviral vector that directs the expression of an CD45 CAR or CD45 polypeptide as well as a non-immunogenic surface marker for in vivo detection, ablation, and potential ex vivo selection. The activated/genetically modified CD45 central memory T cells can be expanded in vitro with IL-2/IL-15 and then cryopreserved. Additional methods of preparing CAR T cells can be found in PCT/US2016/043392. Methods for preparing T cell populations useful for producing engineered T cells are described in, for example, WO 2017/015490 and WO 2018/102761.
The CAR can be transiently expressed in a T cell population by an mRNA encoding the CAR. The mRNA can be introduced into the T cells by electroporation (Wiesinger et al. 2019 Cancers (Basel) 11:1198).
In some embodiments, a composition comprising the CAR T cells comprise one or more of helper T cells, cytotoxic T cells, memory T cells, naïve T cells, regulatory T cells, natural killer T cells, or combinations thereof. In some embodiments, a composition comprising the CAR T cells comprise CD3+, CD5+, CD7+, and TCRαβ+. In some embodiments, a composition comprising the CAR T cells comprise CD8+ CAR T cells are CD8αβ T cells, which have strong cytotoxicity against tumor cells in an antigen specific manner and can potently secret cytokines such as IFNγ. In some embodiments, CAR T cells have predominant homogenous TCR phenotype. In some embodiments, a composition comprising the CAR T cells comprise CD3+CD5+CD7+TCRαβ+CD8αβ+, CD3+CD5+CD7+TCRαβ+CD4+, CD62L+CD45RA+ stem memory T cells, CD62L-CD45RA-CD45RO+ effector memory T cells and CD62L-CD45RA+ effector T cells, and combinations thereof.
In some embodiments, a gene selected from: Transducin Like Enhancer of Split 4 (TLE4) gene, Transmembrane Protein 184B (MEM184B) gene, Eukaryotic Translation Initiation Factor 5A-1 (EIF5A) gene and Ikaros Family Zinc Finger Protein 2 (IKZF2) is knocked out, knocked down, mutated, or down regulated. Preferably, the gene is knocked down or knocked out by gene disruption, e.g., using methods described herein or other gene modification methods known in the art. In some embodiments, the genetic modification method comprises gene editing, homologous recombination, non-homologous recombination, RNA-mediated genetic modification, DNA-mediated genetic modification, zinc finger nucleases, meganucleases, TALEN, or CRISPR/CAS9. In some embodiments, the CRISPR/CAS9 system comprises a gRNA targeting an exon of one of the genes that is to be disrupted.
In some embodiments, a composition comprising CAR T cells or CAR NK cells described herein is administered locally or systemically. In some embodiments, a composition comprising CAR T cells or CAR NK cells described herein is administered by single or repeat dosing. In some embodiments, a composition comprising CAR T cells or CAR NK cells described herein is administered to a patient having a cancer, a pathogen infection, an autoimmune disorder, or undergoing allogeneic transplant.
In some embodiments, the engineered T cells express a CAR targeted to a cancer cell antigen. In some embodiments, the cancer is glioblastoma. In some embodiments, the cancer is selected from the group consisting of blood cancer, B cell leukemia, multiple myeloma, lymphoblastic leukemia (ALL), chronic lymphocytic leukemia, non-Hodgkin's lymphoma, ovarian cancer, prostate cancer, pancreatic cancer, lung cancer, breast cancer, and sarcoma, acute myeloid leukemia (AML).
The materials, methods, and examples are illustrative only and not intended to be limiting. All publications, patent applications, patents, sequences, database entries, and other references mentioned herein are incorporated by reference in their entirety for any and all purposes.
Other features and advantages of the described compositions and methods will be apparent from the following detailed description and figures, and from the claims.
GSCs represent a potentially important cellular target in GBM, as they have been linked to therapeutic resistance, invasion into normal brain, promotion of angiogenesis, and immune modulation (24,25). We hypothesized that systematic interrogation of molecular regulation of CAR T cell efficacy against GBM could be optimized by screening both CAR T cells and GBM cells, thereby informing the interplay between a cell-based therapy and its target population. Here, we developed a robust method for performing whole-genome CRISPR-knockout screens in both GBM cells and human CAR T cells. Using our well-established CAR T cell platform targeting the tumor-associated surface marker interleukin-13 receptor α2 (IL13Rα2) (7,8,26), we identified novel CAR T cell- and tumor-intrinsic targets that substantially improved CAR T cell cytotoxicity against GSCs both in vitro and in vivo. Targeted genetic modification of identified hits in CAR T cells potentiated their long-term activation, cytolytic activity, and in vivo antitumor function against GSCs, demonstrating that CRISPR screen on CAR T cells leads to the discovery of key targets for augmenting CAR T cell therapeutic potency. In parallel, knockout of identified targets in GSCs sensitized them to CAR-mediated killing both in vitro and in vivo, revealing potential avenues for combinatorial inhibitor treatment to augment CAR T cell efficacy. Our findings represent a feasible and highly effective approach to discovering key targets that mediate effective tumor eradication using CAR T cells.
The invention is further described in the following examples, which do not limit the scope of the invention described in the claims.
GSCs were acquired from patient specimens at City of Hope under protocols approved by the IRB, and maintained as tumorspheres in GSC media as previously described (4,91). GSC lines used in this study to test CAR T cell function are IDH1/2-wildtype. The sgRNA library and single-targeted sgRNA lentiviral plasmids (containing a puromycin-resistance gene) for GSC transduction were purchased from Addgene (#73179 and #52961, respectively). Lentiviral particles were generated as previously described (92). For lentiviral transduction, GSC tumorspheres were dissociated into single cells using Accutase (Innovative Cell Technologies), resuspended in GSC media and lentivirus was added at a 1:50 v/v ratio. GSCs were then washed once after 12 hours, resuspended in fresh GSC media and cultured for 3 days. To ensure that only transduced cells were expanded for further assays, GSCs were selected by puromycin (Thermo Fisher Scientific) for 7 continuous days, with a 1:10000 v/v ratio into GSC media.
Naïve and memory T cells were isolated from healthy donors at City of Hope under protocols approved by the IRB (26,30). The constructs of IL13Ra2-targeted and HER2-targeted CARs were described in previous studies (8,26,93). Procedures of CAR-only transduction on primary human T cells were previously described (44). The sgRNA library and single-targeted sgRNA lentiviral plasmids for T cell transduction were purchased from Addgene (#73179 and #52961, respectively). All sgRNA plasmids contain a puromycin-resistance gene. Dual transduction of CAR and sgRNA were performed using modification of previously reported procedures (21). In brief, primary T cells were stimulated with Dynabeads Human T expander CD3/CD28 (Invitrogen) (T cells: beads=1:2) for 24 hours and transduced with sgRNA lentivirus (1:250 v/v ratio). Cells were washed after 6 hours and then transduced with CAR lentivirus (multiplicity of infection [MOI]=0.5). 4 days after CAR transduction, CD3/CD28 beads were removed and cells were resuspended in Lonza electroporation buffer P3 (Lonza, #V4XP-3032) (2×108 cells/mL). Cas9 protein (MacroLab, Berkeley, 40 mM stock) was then added to the cell suspension (1:10 v/v ratio) and electroporation was performed using a 4D-Nucleofactor™ Core Unit (Lonza, #AAF-1002B). Cells were recovered in pre-warmed X-VIVO 15 media (Lonza) for 30 min before proceeding to ex vivo expansion. All T cell transduction and ex vivo expansion experiments were performed in X-VIVO 15 containing 10% FBS, 50 U/ml recombinant human IL-2 (rhIL-2), and 0.5 ng/ml rhIL-15, at 6×105 cells/ml. To ensure that only sgRNA-transduced cells were expanded, puromycin (1:10000 v/v ratio) was added to the media 3 days after electroporation, and puromycin selection was performed for 6 continuous days before CAR T cells were used for further assays. CRISPR screening was performed on two independent donors, and other 2 donors are used to generate IL13Ra2-targeted and HER2-targeted CARs, respectively.
GSCs transduced with the CRISPR KO library were dissociated into single cells, and co-cultured with CAR T cells at an effector: target ratio of 1:2 in culture plates pre-coated with matrigel. After 24 hours, the media containing CAR T cells and tumor debris were removed, and same number of CAR T cells were added in fresh media. 24 hours after the second CAR T cell addition, the media were removed and remaining GSCs were washed with PBS and harvested. Genomic DNA was isolated from the remaining GSCs after co-culture with CAR T cells, as well as GSCs harvested before co-culture and GSCs after monoculture for 48 hours.
T cells transduced with CAR and the CRISPR KO library were co-cultured with GSC at an effector: target ratio of 1:4 in culture plates pre-coated with matrigel. After 48 hours, CAR T cells were re-challenged by GSCs doubling the number of the initial co-culture. 24 hours after the rechallenge, the co-culture was harvested and stained with fluorescence-conjugated antibodies against human CD45 (BD Biosciences Cat #340665, RRID:AB_400075), PD1 (BioLegend Cat #329922, RRID:AB_10933429) and IL13 (BioLegend Cat #501914, RRID:AB_2616746). Different subsets were sorted using an Aria SORP (BD Biosciences): total CAR T cells (CD45+, IL13+), PD1+ CART cells (CD45+, IL13+, PD1+) and PD1− CART cells (CD45+, IL13+, PD1−). Genomic DNA was isolated from the sorted subsets of cells, as well as CAR T cells harvested before co-culture and CAR T cells after monoculture for 72 hours.
FASTQ files were trimmed to 20 bp CRISPR guide sequences using BBDuk from the BBMap (https://jgi.doe.gov/data-and-tools/bbtools) (RRID:SCR_016965) toolkit and quality control as performed using FastQC (RRID:SCR_014583, https://www.bioinformatics.babraha-m.ac.uk/projects/fastqc/). FASTQs were aligned to the library and processed into counts using the MAGECK-VISPR ‘count’ function (https://bitbucket.org/liulab/mageck-vispr/src/master/). β-values were calculated using an MLE model generated independently for each comparison. Non-targeting sgRNAs were used to derive a null distribution to determine p-values.
For in vitro cytotoxicity test, CAR T cells were co-cultured with GSCs at an effector: target ratio of 1:40. After 48 hours of co-culture, the numbers of CAR T cells and GSCs were evaluated by flow cytometry. Flow cytometry assays were performed on GSCs, CAR T cells from monoculture or co-culture with procedures described previously (30). For co-culture, anti-CD45 (BD Biosciences Cat #340665, RRID:AB_400075) staining was used to distinguish GSCs with T cells, and CAR T cells were identified by anti-IL13 (BioLegend Cat #501914, RRID:AB_2616746) staining. Other antibodies used for flow cytometry target: PD-L1 (Thermo Fisher Scientific Cat #17-5983-42, RRID:AB_10597586), TIM3 (Thermo Fisher Scientific Cat #17-3109-42, RRID:AB_1963622), LAG3 (Thermo Fisher Scientific Cat #12-2239-41, RRID:AB_2572596), PD1 (BioLegend Cat #329922, RRID:AB_10933429), CD69 (BD Biosciences Cat #340560, RRID:AB_400523), CD137 (BD Biosciences Cat #555956, RRID:AB_396252) and IL13Ra2 (BioLegend Cat #354404, RRID:AB_11218789). All samples were analyzed via a Macsquant Analyzer (Miltenyi Biotec) and processed via FlowJo v10 (RRID:SCR_008520).
Total mRNA from GSCs or CAR T cells was isolated and purified by RNeasy Mini Kit (Qiagen Inc.) and sequenced with Illumina protocols on a HiSeq 2500 to generate 50-bp reads. Trim Galore (https://www.bioinformatics.babraham.ac.uk/projects/trim_galore/) (RRID:SCR_011847) was used to trim adaptors and remove low quality reads. Reads were quantified against Gencode v29 using Salmon (RRID:SCR_017036, https://combine-lab.github.io/salmon/) with correction for fragment-level GC bias, positional bias and sequence-specific bias. Transcripts were summarized to gene level and processed to transcripts per million (TPM) using the R/Bioconductor (https://www.bioconductor.org/) package DESeq2 (RRID:SCR_000154, https://bioconductor.org/packages/release/bio-c/html/DESeq2.html). Comparisons were performed using contrasts in DESeq2 followed by Benjamini-Hochberg adjustment to correct for false discovery rate.
ClueGO gene set enrichment plots were generated using the ClueGO plugin (http://apps.cytoscape.org/apps/cluego, RRID:SCR_005748) for GO BP, KEGG or Reactome gene sets and visualized in Cytoscape v3.7.2 (https://cytoscape.org/).
GSEA (RRID:SCR_003199) plots were generated from preranked lists using the mean β value as the ranking metric. Reactome networks were created using the Reactome FI plugin (https://reactome.org/tools/reactome-fiviz) with network version 2018 and visualized in Cytoscape. Networks were clustered using built-in network clustering algorithm, which utilizes spectral partition-based network clustering, and node layout and color were determined by module assignment. GSEA plots from RNA-sequencing data were generated from preranked lists. Weighting metrics for preranked lists were generated using the DESeq2 results from the gene knockdown vs. non-targeting control and applying the formula: −log 10(FDR)*log 2(fold change). ssGSEA scores for specific immune or functional pathways were generated using the ssGSEA function from the R/Bioconductor package GSVA (https://bioconductor.org/packages/release/bioc/html/GSVA.html) (94) (93) (93) and plotted using pheatmap (https://cran.r-project.org/web/packages/pheatmap/). ChEA enrichments were performed using Enrichr (https://amp.pharm.mssm.edu/Enrichr/). Barplots for positive or negative gene set enrichments were performed using Metascape (https://metascape.org/gp/index.html) for significantly up- or down-regulated genes (FDR<0.05 and log 2 fold change>1 or <−1).
Reactome networks were derived from RNA-seq data using the Cytoscape Reactome FI plugin (RRID:SCR_003032). A gene list of upregulated (FDR<0.05 and log 2 fold change>1) or downregulated (FDR<0.05 and log 2 fold change<−1) genes plus the target gene (as knockout by CRISPR-Cas9 would not be detected by RNA-seq) was input into Reactome FI and all genes with at least one edge were included in the network plot. Node color (light to dark) and size (small to large) are proportional to node degree. Pathway enrichment was performed on this network of genes using the Reactome FI enrichment option. Boxplots for genes from selected pathways were generated using RNA-seq TPM data. KEGG pathway visualizations were generated using the R/Bioconductor package pathview (https://www.bioconductor.org/packages/release/bioc/html/pathview.html) from for selected pathways and genes were colored based upon the log 2 fold change knockout vs. control.
Single cell RNA-sequencing files were processed using the Cell Ranger workflow (https://support.10xgenomics.com/single-cell-gene-expression/software/overview/welcome). FASTQ files were generated using the Cell Ranger ‘mkfastq’ command with default parameters. FASTQs were aligned to the hg19 genome build using the ‘count’ function and aggregated using the default Cell Ranger ‘aggr’ parameters with normalization performed by subsampling wells to equalize read depth across cells. Downstream analyses were performed using the R/Bioconductor package Seurat (https://satijalab.org/seurat/) (95)(94)(95). Specifically, datasets of stimulated and unstimulated cells in knockout or control populations were merged using the “FindintegrationAnchors” Seurat function. Clustering was performed using UMAP using PCA for dimensional reduction and a resolution of 0.6 from 1 to 20 dimensions. Dead cell clusters were determined by high expression of mitochondrial genes and removed. Samples were then reclustered. Clusters with similar CD4 or CD8, Ki67 and marker expression, determined using the “FindAllMarkers” function that were proximal on the UMAP projection were merged. All plots for gene expression were generated using normalized data from the default parameters of the “NormalizeData” function. Gene expression was visualized on the UMAP projection using the “FeaturePlot” function with a maximum cutoff or gene expression determined on a gene-by-gene basis.
All mouse experiments were performed using protocols approved by the City of Hope IACUC. Orthotopic GBM models were generated using 6- to 8 week-old NOD/SCID/IL2R−/− (NSG) mice (IMSR Cat #JAX:005557, RRID:IMSR_JAX:005557), as previously described (96). Briefly, ffLuc-transduced GSCs (1×105/mouse) were stereotactically implanted (intracranially) into the right forebrain of NSG mice. Randomization was performed after 8 days of tumor injection based on bioluminescent signal, and mice were then treated intracranially with CAR T cells (2×104 or 5×104/mouse as indicated for each experiment). To ensure statistical power, all treatment groups include ≥6 animals. Mice were monitored by the Department of Comparative Medicine at City of Hope for survival and any symptoms related to tumor progression, with euthanasia applied according to the American Veterinary Medical Association Guidelines. Studies were done in both male and female animals. Investigators were not blinded for randomization and treatment.
Analysis of genes in the TCGA dataset was performed using RNA-sequencing TCGA GBM data. Immune infiltration signatures were previously reported (97). GSEA plots for each gene in the context of TCGA GBM data were generated by using the normalized gene expression as a continuous phenotype.
Gene sets derived from TLE4 or IKZF2 knockout were analyzed in the context of CAR T cell non-responder vs. responders from a previous report on patients with CLL (27). Genes upregulated in bulk RNA-seq of CAR T cells following knockout of TLE4 or IKZF2 (FDR<0.05 and log 2 fold change>1) were plotted by their fold change expression in stimulated vs. unstimulated CAR T cells for responders or non-responders. Fold change was calculated using DESeq2 for stimulated vs. unstimulated cells independently for each group (non-responder or complete responder). Cluster 10-enriched genes in the TLE4 knockout and control sc-seq data, identified by the “FindAllMarkers” function in Seurat subsetted for overexpressed genes, were plotted similarly. Genes upregulated (>0.4 log 2 fold change of normalized counts) in sc-seq for IKZF2 knockout vs. control in stimulated CAR T cells were plotted similarly.
CAR T cell functional data (tumor killing, expansion, survival of tumor-bearing mice) were analyzed via GraphPad Prism. Group means±SEM were plotted. Methods of p-value calculations are indicated in figure legends.
The fitness of CAR T cell products correlates with clinical responses (27,28), indicating that key regulators of CAR T cell function can be targeted to potentiate therapeutic efficacy. T cell exhaustion resulting from chronic tumor exposure limits CAR T cell antitumor responses (29). To identify the essential regulators of T cell functional activity in an unbiased manner, we performed genome-wide CRISPR screen adapting our previously developed in vitro tumor rechallenge assay, which differentiates CAR T cell potency in the setting of high tumor burden and reflects in vivo antitumor activity (30,31). IL13Ra2-targeted CAR T cells from two human healthy donors were lentivirally transduced to express the Brunello short-guide RNA (sgRNA) library (32) and the CAR construct, then electroporated with Cas9 protein.
CAR T cells harboring CRISPR-mediated knockouts were recursively exposed to an excess amount of PBT030-2 GSCs (
We interrogated the 220 targets enriched in PD1-negative cells common between two T cell donors, focusing on four representative genes identified in the top third of hits, which have not been previously explored for their role in enhancing CAR T cell function. These included the high-ranking hits: Eukaryotic Translation Initiation Factor 5A-1 (EIF5A; Gene ID 1984), transcription factor Transducin Like Enhancer of Split 4 (TLE4; Gene ID 7091), Ikaros Family Zinc Finger Protein 2 (IKZF2; Gene ID 22807), and Transmembrane Protein 184B (TMEM184B; Gene ID 25829) (
TLE4 is a transcriptional co-repressor of multiple genes encoding inflammatory cytokines (45) and IKZF2 is upregulated in exhausted T cells (37,46,47), supporting potential roles in inhibiting CAR T cell function. To elucidate molecular mechanisms underlying the regulation of CAR T cell activity, we compared the transcriptomes of CAR T cells with individual knockouts against cells transduced with non-targeted sgRNA (sgCONT). TLE4 KO in CAR T cells upregulated critical regulators of T cell activation, including the transcription factor EGR1, which promotes Th1 cell differentiation (48), and the metabolic regulator BCAT, which mediates metabolic fitness in activated T cells (49) (
Whole-transcriptome analyses following TMEM184B or EIF5A KO revealed convergence of altered pathways, similar to those induced by TLE4 or IKZF2 KO, including the upregulation of BCAT1, EGR1, and IL17RB (
To determine the impact of TLE4 or IKZF2 KO on specific subpopulations of CAR T cells, we performed comparative single-cell RNA-sequencing (scRNAseq) on KO and control CAR T cells with or without stimulation by tumor cells. Comparing TLE4-KO cells with control CAR T cells by unbiased clustering of pooled data identified 10 different clusters, the distribution of which was greatly influenced by stimulation (
Comparison between IKZF2-KO cells and control CAR T cells identified 10 clusters using unbiased clustering of pooled data (
Augmenting efficacy of CAR T cells against GBM can be approached by studying T cells themselves, as above, which may inform targeted KOs in addition to CAR engineering for enhancing CAR activity. Reciprocal screening of GBM cells, especially GSCs, potentially informs interactions with CAR T cells to predict clinical responsiveness to CAR T cell therapy. To identify potential genes in GSCs that promote resistance to CAR-mediated cytotoxicity, we performed genome-wide CRISPR screens on two independent patient-derived GSC lines (PBT030-2 and PBT036), both derived from primary GBM tumors with high expression of IL13Ra2 (33). To identify tumor cell targets that rendered GBM cells more susceptible to T cell immunotherapy, we subjected GSCs to two rounds of co-culture with IL13Ra2-targeted CAR T cells (
Next, we sought to confirm and further characterize the function of common top hits whose deletion promoted CAR killing (
RELA (also known as p65) is an NF-κB subunit that regulates critical downstream effectors of immunosuppressive pathways in tumors (60,61). NPLOC4 mediates nuclear pore transport of proteins, but its role in cancer or immune modulation remains unclear. To elucidate the mechanism by which these genes mediate GSC sensitivity to CAR T cell killing, we performed in-depth characterization of GSCs harboring knockout of each gene. The increased sensitivity was not a result of alterations in target antigen expression on GSCs (
Next, we used an orthotopic intracranial patient-derived xenograft model to evaluate whether modulating the identified targets on GSCs enhanced the antitumor function of CAR T cells in a preclinical setting. Established GBM PDXs were treated with CAR T cells delivered intracranially into the tumors, mimicking our clinical trial design of CAR T cell administration to patients with GBMs (7,66). First, we used CAR T cells without CRISPR knockout to treat control, RELA-KO, or NPLOC4-KO tumors. A limited number of CAR T cells (50,000/mouse) completely eradicated xenografts derived from RELA-KO or NPLOC4-KO GSCs, whereas the same CAR T cells were only partially effective against tumors established with sgCONT-GSCs (
To further dissect the roles of RELA and NPLOC4 in immune modulation in GBM, we analyzed 41 GSC samples, and found that high RELA- or NPLOC4-expressing GSCs showed enrichment in immune-suppression signatures (
We next evaluated the molecular targets identified in our CAR T cell screen in vivo, with the goal of establishing clinically translatable strategies to improve CAR T cell function. The antitumor function of different CAR T cells were tested against tumors without CRISPR knockouts, with a further limited CAR T cell dose (20,000/mouse) showing enhanced survival benefit as compared to the control CAR T cells failed to achieve long-term tumor eradication (
We then investigated whether the CAR T cell targets indicate the potency of clinical therapeutic products. We then mapped upregulated genes in IKZF2-KO CAR T cells compared to control CAR T cells after tumor stimulation, with the transcriptomes of CAR T cell products from patients with chronic lymphocytic leukemia (CLL) achieving complete responses (CR) or no responses (NR) (27). Supporting our results, these genes were induced to a greater degree after CAR stimulation in the products from patients achieving CR (
To further understand how TLE4 and IKZF2 contribute to the function of clinical CAR T cell products, we analyzed scRNAseq from 24 patient-derived CD19-CAR T cell products (68). An unbiased clustering of the scRNAseq data revealed that IKZF2 expression was highly enriched in cluster 7 (
T cell-based therapies may offer several advantages in GBM therapy. T cell-based therapies, especially when delivered into the cerebrospinal fluid (CSF), traffic to multifocal tumor populations within the central nervous system (CNS) (8,70-72), thus overcoming challenges associated with the blood-brain barrier that limits the CNS penetration of most pharmacologic agents. T cell therapies compensate for cellular plasticity within brain tumors more effectively than traditional pharmacologic agents. GBMs display striking intratumoral heterogeneity, and tumor cells readily compensate for targeted agents against specific molecular targets. With T cell therapy targeting different antigens, personalized treatments based on the antigen expression profile of individual tumors may be designed. T cell-based therapies induce secondary responses that augment endogenous anti-tumor responses. Adoptive cell transfer, especially CAR T therapies, have been investigated in clinical trials for GBM patients, but efficacy has been restricted to limited cases (11). Our focus on CAR T cells was prompted not only by the potential value for clinical translation, but also as our findings inform a broader understanding of T cell function in brain tumor biology.
Previous genetic screens used to identify interactions between immune cells and tumor cells have largely focused on the tumor cells (18,19,29), as these cells are easier to manipulate genetically. Screens on tumor-reactive mouse T cells have also been reported (20,73,74) given the establishment of Cas9-knockin mouse strain (75), as well as the convenience to acquire large numbers of these cells. Here, we interrogated both the human CAR T cell and tumor cell compartments. The screening strategy on CAR T cells was greatly facilitated by the development of the non-viral Cas9 expression system in primary human T cells (21). Here, the screening on tumor cells was performed on two independent GSCs, displaying a relatively narrow range of shared molecular targets involved in mediating responses to CAR T cells in our studies, which might be a consequence of subtype difference between these GSC lines (33). The screening identified both rational targets (RELA/p65) and novel targets (NPLOC4) in immune regulation, which were not restricted to a specific GBM molecular subclass. NPLOC4 displayed unexpected associations with GBM-targeting immune cell activity, as NPLOC4-KO in GSCs led to enhanced potency of CAR T cells and increased cytokine production in GSCs, although the detailed mechanism awaits further investigation. In the analyses of GSC models and TCGA database, high RELA and NPLOC4 expression was associated with immunosuppressive signatures. More specifically, higher expression of RELA and NPLOC4 in GBMs correlated with low infiltration of both CD4+ and CD8+ T cells, indicating that targeting these genes may confer immune modulatory effect and enhance antitumor T cell responses in GBMs.
The assay used for CRISPR screening in T cells is crucial for reliable readouts and is required for its sensitivity to differentiate effective versus non-effective therapies. Although the in vivo antitumor efficacy in mouse models has been the standard to evaluate the functional quality of T cells in adoptive transfer, the utilization of this system in screening has been controversial. Tumor-infiltrating T cells harvested after the injection of therapeutic cells display signatures of tumor reactivity (73) or, conversely, T cell exhaustion (40). The differential results appear model dependent, leading to mixed interpretation of the results. The co-culture assays that we used in this study identified key regulators by creating challenging screening environments. For the screening on GSCs, two rounds of short-term (24 h) killing with relatively large number of T cells (total E:T=1:1) was performed and GSCs were harvested immediately after the second round of killing, minimizing the effect of knocking out genes essential for the GSC growth. For the screening on CAR T cells, a repetitive challenge assay was used with excessive number of GSCs (total E:T=1:12), which we have shown to induce CAR T cell exhaustion (30). The screen was performed by comparing a less exhausted (PD1-negative) with a more exhausted (PD1-positive) subset, informing prioritization for maintenance of recursive killing function, while reducing the noise from tumor cell or T cell growth. The screening was performed with two independent CAR T cell donors, and the relatively small proportion of overlapping hits between the two donors was expected and consistent with previous studies (21,76), due to the variation in T cell populations between individuals. The target validation was done with different T cell donors and CAR platforms; therefore, the discovered immunotherapy targets may be generalizable to multiple CAR designs. While we validated 4 representative genes, the screening on CAR T cells resulted in over 200 potential targets involved in critical pathways of T cell biology and activation, offering additional targets for future investigation of CAR refinement. One limitation of our approach, however, is the exclusion of apoptosis pathways in tumor cells due to its critical role in tumor cell growth, which have been demonstrated as important regulators of CAR T cell-mediated tumor killing as well as tumor-induced CAR T cell exhaustion (29).
T cell exhaustion has been considered as one of the major hurdles for reducing CAR T cell potency (77-79). Blocking/knockout of inhibitory receptors is being rigorously investigated to augment CAR activity or other tumor targeting T cells (29,80,81). T cell exhaustion is a feedback mechanism after activation, occurring upon recursive exposure to antigens in the contexts of chronic infection or the tumor microenvironment (78,82) compromising their antitumor potency (79). Here, we observed that TLE4 or IKZF2 KO resulted in unstimulated CAR T cells to express transcriptional profiles of activation, while prohibiting exhaustion. AP-1 family transcription factors FOS and JUN, which were induced after both TLE4- and IKZF2-KO, provide a possible mechanism by which CAR T cell fitness was protected. The protein c-Jun forms homodimers or c-Fos/c-Jun heterodimers to initiate transcription of proinflammatory cytokines, and heterodimers with other co-factors (including BATF, IRF4, JUNB, and JUND) induce inhibitory receptors or suppress transcriptional activity of c-Jun (83-86). FOS was more upregulated than suppressive co-factors after TLE4-KO; therefore, driving T cell activation together with a protection from exhaustion, which was reminiscent of the effect after expressing c-Jun in CAR T cells with tonic signaling (55). In IKZF2-KO cells, however, the uncoupling of activation from exhaustion signatures was likely influenced by the upregulation of cytokines CCL3 and CCL4, which inversely correlated with PD-1 expression during T cell exhaustion (87). Both TLE4 or IKZF2 KO in CAR T cells upregulated essential regulators for Th1 cell differentiation (BCAT and EGR1, respectively), consistent with a previously identified role of this T cells population in mediating antitumor immunity (88,89). Consequently, targeted KOs in CAR T cells enhanced not only killing, but also expansion potential, which is correlated with clinical responses (90). Although it remains unresolved if these KOs potentiate CAR activity in immune-competent settings, our results have revealed the feasibility that CAR T cells can be modified for their activation/exhaustion signals to achieve functional improvement in clinically-relevant models. Consistent with these findings, we explored public databases of scRNAseq on patient-derived CAR T cell products and discovered that high IKZF2 expression and TLE4 activity were associated with other suppressive/exhaustion signatures of CAR T cells as well as poor clinical responses.
Single cell analyses reveal subset composition within a mixed cell sample, such as CAR T cells, in which minority populations serve critical roles. scRNAseq revealed that CAR activation, rather than genetic modification of CAR T cells (TLE4 or IKZF2 KO), resulted in a major cluster switch, which is consistent with the observation that TLE or IKZF2 KO in monoculture CAR T cells did not dramatically alter transcriptional profiles, as suggested by bulk RNA-seq. Following tumor challenge, knockout of targeted genes upregulated T cell activation markers and proinflammatory cytokines across different clusters, especially IFNG and CCL3, which showed similar induction by both TLE-KO and IKZF2-KO. Further, after CAR activation, TLE4 KO maintained a specific cluster, which existed pre-activation, and IKZF2 KO led to the emergence of a new cluster. The transcriptional signature of these clusters (expression of several costimulation molecules and cytokines) indicated their critical role in mediating effector function of CAR T cells. Therefore, the superior functions of TLE4-KO or IKZF2-KO CAR T cells were likely the result of a generally elevated activation state, as well as the stimulatory effect from critical subsets. Our scRNAseq results also suggested the existence of Treg-like populations, the expansion of which was seen after CAR activation and can be reduced by IKZF2-KO. The suppressive function of these cells still requires further investigation, but these results indicate the potential of enhancing CAR function through inhibiting differentiation towards Treg-like cells. Both TLE4-KO and IKZF2-KG CAR T cells appear to modify specific CD4+ T cell subsets, which supports our previous observation that CD4+ CAR T cells play a critical role in mediating potent effector function (30).
Additional genes that can be knocked out in T cells harboring a CAR to improve CAR T cell function can include.
It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.
This application claims the benefit of U.S. Provisional Application Ser. No. 63/117,439, filed on Nov. 23, 2020. The entire contents of the foregoing are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2021/060654 | 11/23/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63117439 | Nov 2020 | US |
