Patent Application
20210107996
The Sequence Listing is concurrently submitted herewith with the specification as an ASCII formatted text file via EFS-Web with a file name of Sequence Listing.txt with a creation date of May 23, 2019, and a size of 66.1 kilobytes. The Sequence Listing filed via EFS-Web is part of the specification and is hereby incorporated in its entirety by reference herein.
The present invention relates to PLAP (placental alkaline phosphatase)-CAR. The present invention is also directed to a method for treating PLAP-positive cancer cells by administering PLAP-CAR-T cells, PLAP-CAR-natural killer cells, or PLAP-CAR-macrophages to the patients.
Immunotherapy is emerging as a highly promising approach for the treatment of cancer. T cells or T lymphocytes, the armed forces of our immune system, constantly look for foreign antigens and discriminate abnormal (cancer or infected cells) from normal cells. Genetically modifying T cells with CARs is the most common approach to design tumor-specific T cells. CAR-T cells targeting tumor-associated antigens (TAA) can be infused into patients (called adoptive cell transfer or ACT) representing an efficient immunotherapy approach. The advantage of CAR-T technology compared with chemotherapy or antibody is that reprogrammed engineered T cells can proliferate and persist in the patient (“a living drug”).
CARs (Chimeric antigen receptors) usually consist of a monoclonal antibody-derived single-chain variable fragment (scFv) linked by a hinge and transmembrane domain to a variable number of intracellular signaling co-stimulatory domains: (i) CD28, Ox-40, CD137 (4-1BB), GITR or other co-stimulatory domains; and (ii) a single, cellular activating, CD3-zeta domain after co-stimulatory domains (
Natural-killer (NK) cells are CD56+CD3− large granular lymphocytes that can kill virally infected and transformed cells, and constitute a critical cellular subset of the innate immune system. Unlike cytotoxic CD8+T lymphocytes, NK cells launch cytotoxicity against tumor cells without the requirement for prior sensitization, and can also eradicate MHC-I negative cells.
CAR-T cell therapy had successful clinical results in the treatment of hematological cancer patients [1-5]. Chimeric antigen receptor contains single chain fragment variant (ScFv) of antibody targeting cancer cell surface antigen fused to a hinge, transmembrane domain, co-stimulatory (CD28, 41-BB or other domains) and CD3 activation domain [1,6],[7,8]. Recently two CD19-CAR-T cell therapies (Kymriah and Yescarta) were approved by FDA for the treatment of hematological cancers based on their high response rate in acute lymphoblastic leukemia and other hematological cancers in clinical trials [3], [9-11]. There are also several other CAR-T cells that are tested in clinical trials such as CD22-CAR-T cells [12] for B-cell lymphoma, BCMA-CAR-T cells for multiple myeloma [13-14].
In terms of solid tumors, CAR-T cell therapy still has many challenges for targeting solid cancers due to on-target off-tumor effects, suppressive tumor microenvironment, decreased CAR-T cell access to the tumor, T cell exhaustion and low persistency [15], [16-18]. The main challenge with CAR-T cells targeting solid tumors is that most tumor solid tumor antigens are expressed in normal tissues.
PLAP is a placental alkaline phosphatase that is encoded by ALPP gene. PLAP is a metalloenzyme enzyme that catalyzes the hydrolysis of phosphoric acid monoesters. PLAP is expressed mainly in placental and endometrial tissues, it is not expressed in normal tissues.
PLAP has high expression in placenta [19], and it is not expressed in most normal tissues except of testis [20]. It was found to be overexpressed in malignant seminoma, teratoma [20], [21], ovarian and cervical carcinoma [22], [23], [24], and colon adenocarcinoma [25]. PLAP was detected in lung, pancreas, stomach tumors [39]. PLAP was also detected among several other membrane-bound proteins in exosomes of non-small cell lung cancer patients with a potential to be prognostic marker [26].
Human PLAP is a 535 amino-acid glycosylated protein encoded by ALPP gene with 1-22 signaling peptide, then extracellular domain (23-506), 513-529 transmembrane domain (sequence is shown below, transmembrane domain is underlined) Uniprot database (www.uniprot.org/uniprot/P05187; NM_001632). Its sequence is shown below (SEQ ID NO: 1).
MLGPCMLLLL LLLGLRLQLS LGTIPVEEEN PDFWNREAAE
ALGAAKKLQP AQTAAKNLII FLGDGMGVST VTAARILKGQ
KKDKLGPEIP LAMDRFPYVA LSKTYNVDKH VPDSGATATA
YLCGVKGNFQ TIGLSAAARF NQCNTTRGNE VISVMNRAKK
AGKSVGVVTT TRVQHASPAG TYAHTVNRNW YSDADVPASA
RQEGCQDIAT QLISNMDIDV ILGGGRKYMF RMGTPDPEYP
DDYSQGGTRL DGKNLVQEWL ARKQGARYVW NRTELMQASL
DPSVTHLMGL FEPGDMKYEI HRDSTLDPSL MEMTEAALRL
LSRNPRGFFL FVEGGRIDHG HHESRAYRAL TETIMFDDAI
ERAGQLTSEE DTLSLVTADH SHVFSFGGYP LRGSSIFGLA
PGKARDRKAY TVLLYGNGPG YVLKDGARPD VTESESGSPE
YRQQSAVPLD EETHAGEDVA VFARGPQAHL VHGVQEQTFI
AHVMAFAACL EPYTACDLAP PAGTTDAAHP GRSVVPALLP
LLAGTLLLLE TATAP
There are four distinct but related alkaline phosphatases: intestinal (ALPI) (NM_001631); placental; placental-like (ALPPL2) (NM_031313) which are all encoded by gene on at chromosome 2 and liver/bone/kidney (ALPL) (tissue-nonspecific) (NM_000478) encoded by gene on chromosome 1.
As used herein, “adoptive cell therapy” (ACT) is a treatment that uses a cancer patient's own T lymphocytes, or NK cells, or other hematopoietic cells such as macrophages, induced pluripotent cells, with anti-tumor activity, expanded in vitro and reinfused into the patient with cancer.
As used herein, “affinity” is the strength of binding of a single molecule to its ligand. Affinity is typically measured and reported by the equilibrium dissociation constant (KD or Kd), which is used to evaluate and rank order strengths of bimolecular interactions.
As used herein, a “chimeric antigen receptor (CAR)” means a fused protein comprising an extracellular domain capable of binding to an antigen, a transmembrane domain derived from a polypeptide different from a polypeptide from which the extracellular domain is derived, and at least one intracellular domain. The “chimeric antigen receptor (CAR)” is sometimes called a “chimeric receptor”, a “T-body”, or a “chimeric immune receptor (CIR).” The “extracellular domain capable of binding to an antigen” means any oligopeptide or polypeptide that can bind to a certain antigen. The “intracellular domain” means any oligopeptide or polypeptide known to function as a domain that transmits a signal to cause activation or inhibition of a biological process in a cell.
As used herein, a “domain” means one region in a polypeptide which is folded into a particular structure independently of other regions.
As used herein, a “single chain variable fragment (scFv)” means a single chain polypeptide derived from an antibody which retains the ability to bind to an antigen. An example of the scFv includes an antibody polypeptide which is formed by a recombinant DNA technique and in which Fv regions of immunoglobulin heavy chain (H chain) and light chain (L chain) fragments are linked via a spacer sequence. Various methods for preparing an scFv are known to a person skilled in the art.
As used herein, a “tumor antigen” means a biological molecule having antigenicity, expression of which causes cancer.
The inventors have discovered that PLAP is a unique tumor marker and that PLAP can be advantageously used to prepare PLAP-CAR T cells or PLAP-NK cells, which can be used for CAR-T cell therapy or CAR-NK cell therapy, because PLAP is not expressed in normal tissues. Unlike other tumor markers that are expressed in low levels in normal tissues, the advantage of PLAP target not expressed in most normal tissues but only in placenta and testis is that PLAP-CAR-T cells/PLAP-NK cells do not react against normal tissues and thus they are safe and have low toxicity.
The present invention provides CAR-T cells and NK cells that target PLAP tumor antigen which is highly overexpressed in many types of cancer such as ovarian, seminoma, and colon cancer. The PLAP-CAR-T cells and PLAP-NK cells of the present invention have high cytotoxic activity against several cancer cells: colon and ovarian cancer cell lines.
The present invention is directed to a chimeric antigen receptor fusion protein comprising from N-terminus to C-terminus: (i) a single-chain variable fragment (scFv) comprising VH and VL, wherein scFv binds to human PLAP, (ii) a transmembrane domain, (iii) a co-stimulatory domain of CD28, and (iv) an activating domain.
In one embodiment, the PLAP antibody is a mouse antibody, and VH has the amino acid sequence of SEQ ID NO: 5 and VL has the amino acid sequence of SEQ ID NO: 6.
In one embodiment, the PLAP antibody is a humanized antibody, and VH has the amino acid sequence of SEQ ID NO: 16, 21, 26, 30, or 34, and VL has the amino acid sequence of SEQ ID NO: 22.
In one embodiment, the scFv comprises the amino acid sequence of SEQ ID NO: 8, 18, 23, 27, 31, or 35; or an amino acid sequence having at least 95%, 96%, 97%, 98%, or 99% sequence identity thereof, provided that the sequence variation is in the non-CDR framework regions.
In one embodiment, the CAR comprises the amino acid sequence of SEQ ID NO: 5, 15, 20, 25, 29, or 33; or an amino acid sequence having at least 95%, 96%, 97%, 98%, or 99% sequence identity thereof, provided that the sequence variation is not in the CDR regions.
The sequence variation, i.e., the amino acid changes are preferably of a minor amino acid change such as a conservative amino acid substitution. A conservative amino acid substitution is well-known to a person skilled in the art.
The present invention is directed to an adoptive cell therapy method for treating cancer, comprising the step of administering PLAP CAR-T cells, PLAP CAR-NK cells, or PLAP CAR-macrophages to a subject suffering from cancer, wherein the cancer is selected from the group consisting of colon cancer, lung cancer, pancreatic cancer, stomach cancer, testicular cancer, teratoma, seminoma, ovarian cancer, and cervical cancer, and the cancer is PLAP-positive.
Suitable antibody useful for PLAP CAR includes mouse PLAP antibody against PLAP and humanized PLAP antibody against PLAP. In one embodiment, the antibody has a high affinity against PLAP.
The CAR of the present invention comprises a single chain variable fragment (scFv) that binds specifically to PLAP. The heavy chain (H chain) and light chain (L chain) fragments of an anti-PLAP antibody are linked via a linker sequence. For example, a linker can be 5-20 amino acids. The scFv structure can be VL-linker-VH, or VH-linker-VL, from N-terminus to C-terminus.
The CAR of the present invention comprises a transmembrane domain which spans the membrane. The transmembrane domain may be derived from a natural polypeptide, or may be artificially designed. The transmembrane domain derived from a natural polypeptide can be obtained from any membrane-binding or transmembrane protein. For example, a transmembrane domain of a T cell receptor α or β chain, a CD3 zeta chain, CD28, CD3-epsilon, CD45, CD4, CD5, CD8, CD9, CD16, CD22, CD33, CD37, CD64, CD80, CD86, CD134, CD137, ICOS, CD154, or a GITR can be used. The artificially designed transmembrane domain is a polypeptide mainly comprising hydrophobic residues such as leucine and valine. It is preferable that a triplet of phenylalanine, tryptophan and valine is found at each end of the synthetic transmembrane domain. In preferred embodiments, the transmembrane domain is derived from CD28 or CD8, which give good receptor stability.
In the present invention, the co-stimulatory domain is selected from the group consisting of human CD28, 4-1BB (CD137), ICOS-1, CD27, OX 40 (CD137), DAP10, and GITR (AITR).
The endodomain (the activating domain) is the signal-transmission portion of the CAR. After antigen recognition, receptors cluster and a signal is transmitted to the cell. The most commonly used endodomain component is that of CD3-zeta (CD3 Z or CD3ζ), which contains 3 ITAMs. This transmits an activation signal to the T cell after antigen is bound. CD3-zeta may not provide a fully competent activation signal and additional co-stimulatory signaling may be needed. For example, one or more co-stimulating domains can be used with CD3-Zeta to transmit a proliferative/survival signal.
The CAR of the present invention may comprise a signal peptide N-terminal to the ScFv so that when the CAR is expressed inside a cell, such as a T-cell, NK cells, or macrophages, the nascent protein is directed to the endoplasmic reticulum and subsequently to the cell surface, where it is expressed. The core of the signal peptide may contain a long stretch of hydrophobic amino acids that has a tendency to form a single alpha-helix. The signal peptide may begin with a short positively charged stretch of amino acids, which helps to enforce proper topology of the polypeptide during translocation. At the end of the signal peptide there is typically a stretch of amino acids that is recognized and cleaved by signal peptidase. Signal peptidase may cleave either during or after completion of translocation to generate a free signal peptide and a mature protein. The free signal peptides are then digested by specific proteases. As an example, the signal peptide may derive from human CD8 or GM-CSF, or a variant thereof having 1 or 2 amino acid mutations provided that the signal peptide still functions to cause cell surface expression of the CAR.
The CAR of the present invention may comprise a spacer sequence as a hinge to connect scFv with the transmembrane domain and spatially separate antigen binding domain from the endodomain. A flexible spacer allows to the binding domain to orient in different directions to enable its binding to a tumor antigen. The spacer sequence may, for example, comprise an IgG1 Fc region, an IgG1 hinge or a CD8 stalk, or a combination thereof. A human CD28 or CD8 stalk is preferred.
The present invention provides a nucleic acid encoding the CAR described above. The nucleic acid encoding the CAR can be prepared from an amino acid sequence of the specified CAR by a conventional method. A base sequence encoding an amino acid sequence can be obtained from the aforementioned NCBI RefSeq IDs or accession numbers of GenBenk for an amino acid sequence of each domain, and the nucleic acid of the present invention can be prepared using a standard molecular biological and/or chemical procedure. For example, based on the base sequence, a nucleic acid can be synthesized, and the nucleic acid of the present invention can be prepared by combining DNA fragments which are obtained from a cDNA library using a polymerase chain reaction (PCR).
The nucleic acid encoding the CAR of the present invention can be inserted into a vector, and the vector can be introduced into a cell. For example, a virus vector such as a retrovirus vector (including an oncoretrovirus vector, a lentivirus vector, and a pseudo type vector), an adenovirus vector, an adeno-associated virus (AAV) vector, a simian virus vector, a vaccinia virus vector or a Sendai virus vector, an Epstein-Barr virus (EBV) vector, and a HSV vector can be used. As the virus vector, a virus vector lacking the replicating ability so as not to self-replicate in an infected cell is preferably used.
For example, when a retrovirus vector is used, the process of the present invention can be carried out by selecting a suitable packaging cell based on a LTR sequence and a packaging signal sequence possessed by the vector and preparing a retrovirus particle using the packaging cell. Examples of the packaging cell include PG13 (ATCC CRL-10686), PA317 (ATCC CRL-9078), GP+E-86 and GP+envAm-12, and Psi-Crip. A retrovirus particle can also be prepared using a 293 cell or a 293T cell having high transfection efficiency. Many kinds of retrovirus vectors produced based on retroviruses and packaging cells that can be used for packaging of the retrovirus vectors are widely commercially available from many companies.
The present invention provides T cells, or NK cells, or macrophages, modified to express the chimeric antigen receptor fusion protein as described above. CAR-T cells, CAR-NK cells, or CAR-macrophages of the present invention bind to a specific antigen via the CAR, thereby a signal is transmitted into the cell, and as a result, the cell is activated. The activation of the cell expressing the CAR is varied depending on the kind of a host cell and an intracellular domain of the CAR, and can be confirmed based on, for example, release of a cytokine, improvement of a cell proliferation rate, change in a cell surface molecule, or the like as an index.
T cells, or NK cells, or macrophages, modified to express the CAR can be used as a therapeutic agent for a disease. The therapeutic agent comprises the T cells expressing the CAR as an active ingredient, and may further comprise a suitable excipient. Examples of the excipient include pharmaceutically acceptable excipients known to a person skilled in the art.
This application demonstrates the efficacy of CAR-T cells targeting PLAP antigen that is overexpressed in colon cancer tumors. This application demonstrates that PLAP-CAR-T cells specifically decreases viability of PLAP-positive colon cancer cells but not PLAP-negative cancer cells. PLAP-CAR-T cells secrets significant level of IFN-gamma after co-incubation with PLAP-positive colon cancer cells but not after co-incubation with PLAP-negative cancer cells. This application demonstrates that PLAP-CAR-T cells significantly decreases Lovo (positive PLAP-colon cancer cells) xenograft tumor growth in vivo. There are no increase of AST, ALT or amylase enzyme levels in mouse blood and no decrease of mouse body weight after treating mice with hPLAP-CAR-T cells demonstrating no toxic effect of hPLAP-CAR-T cells in vivo. In addition, combination of hPLAP-CAR-T cells with PD-1 or LAG-3 antibodies increased efficacy of CAR-T cells against colon cancer cells.
The inventors found that PLAP-CAR-T cells significantly killed all PLAP-positive cancer cells, and did not kill PLAP-negative colon cancers. This implies high specificity of PLAP-CAR-T cells. In addition, Lovo and Caco-2 colon cancer cells differed in up-regulation of PDL-1 by CAR-T cells. Lovo colon cancer cell induced PDL-1 in response to PLAP-CAR-T cells, while Caco-2 cells did not. Both of cell lines were effectively killed by hPLAP-CAR-T cells independently of induction of PDL-1 expression. The humanized PLAP-CAR-T cells killed faster Lovo cells than Caco-2 cells and secreted more IFN-gamma against Lovo colon cancer cells than against Caco-2 cells. In addition, T cells and Mock CAR-T cells had more activity in Lovo cells that in Caco-2 cells. This show that hPLAP-CAR-T cells can overcome PDL-1 up-regulation in Lovo cells. This was shown when Lovo cells were pretreated with IFN-gamma to up-regulate PDL-1, PLAP-CAR-T cells effectively killed Lovo cells. Colon cancer with Kras mutations were shown to be resistant to therapies such as Cetuximab (Erbitux) [40], while hPLAP-CAR-T cells effectively killed two different colon cancer cell lines: Lovo (codon 13 mutation: G13D) and LS123 (codon 12 mutation: G12D). This is another advantage of hPLAP-CAR-T cells against solid tumors with Kras mutations responsible for resistance to other therapies.
PLAP-CAR-T cells up-regulated PD-1 and LAG-3 after co-culturing with PLAP-positive colon cancer cell lines but did not increase with PLAP-negative colon cancer cell lines. The inventors have found dose-dependent up-regulation of PDL-1 in response to PLAP-CAR-T cells in Lovo colon cancer cell lines. PD-1, PDL-1 or LAG-3 antibody in combination with PLAP-CAR-T cells significantly increased CAR-T induced cytotoxicity and IFN-gamma secretion against Lovo cancer cells. Thus, checkpoint inhibitors can decrease exhaustion of CAR-T cells and provide basis for combination therapy.
PLAP scFv-(CD28, OX-40, 4-1BB, or GITR)-CD3 zeta CAR-T cells, CAR-NK cells, or CAR-macrophages can be used in combination with different chemotherapy: checkpoint inhibitors; targeted therapies, small molecule inhibitors, and antibodies.
Tags (Flag tag or other tags) conjugated PLAP scFv can be used for CAR generation.
Third generation CAR-T or other co-activation signaling domains can be used for the PLAP-scFv inside CAR.
Bispecific PLAP- and other antigens (EGFR, HER-2, VEGFR, NGFR) CAR-T cells, CAR-NK cells, or CAR-macrophages can be used for immunotherapy. The construct of the bispecific CAR-T cells contain a first scFv against PLAP, and a second scFv against a second tumor antigen. CAR-T cells with bispecific antibody can target cancer cells that overexpress two tumor antigens more effectively and specifically.
Combination of PLAP-CAR-T cells, CAR-NK cells, or CAR-macrophages with CAR-T cells, CAR-NK cells, or CAR-macrophages targeting other tumor antigens or tumor microenvironment (e.g. VEGFR-1-3), i.e., dual CAR-T cells, CAR-NK cells, or CAR-macrophages, can be used to enhance activity of monotherapy PLAP-CAR.
PLAP-CAR-T cells, CAR-NK cells, or CAR-macrophages can be used to activate phagocytosis and block “don't eat” signaling.
PLAP-CAR-NK cells are safe effector cells, as they may avoid the potentially lethal complications of cytokine storms, tumor lysis syndrome, and on-target, off-tumor effects.
Anti-PLAP antibody h2, h4 and h5 VH and VL sequences can be used as one arm of a bi-specific antibody.
Both PLAP-CAR-T cells and bi-specific antibodies containing anti-PLAP VH and VL can be used in combination with checkpoint inhibitors (PDL-1 antibody, PD-1 antibody, LAG-3 antibody, TIM-3 antibody, TIGIT antibody, and other antibodies), and with chemotherapies to improve efficacy against cancer cells.
The following examples further illustrate the present invention. These examples are intended merely to be illustrative of the present invention and are not to be construed as being limiting.
HEK293FT cells from AlStem (Richmond, Calif.) were cultured in Dulbecco's Modified Eagle's Medium (DMEM) plus 10% FBS and 1% penicillin/streptomycin. Human peripheral blood mononuclear cells (PBMC) were isolated from whole blood obtained from the Stanford Hospital Blood Center, Stanford, Calif. according to IRB-approved protocol using Ficoll-Paque solution (GE Healthcare). Colon cancer cell lines: PLAP-negative: SW620, HT29, HCT116 and PLAP-positive: Lovo, Caco-2, LS123 were obtained from Dr. Walter Bodmer (Oxford, UK), whose laboratory authenticated cell lines using SNPs, Sequenom MassARRAY iPLEX and HumanOmniExpress-24 BeadChip arrays, and tested for the absence of Mycoplasma as described [28-29]. The cell lines were cultured in DMEM plus 10% FBS and penicillin/streptomycin. The list of 117 colon cancer cell lines from W. Bodmer laboratory which were used for PLAP mRNA level detection is shown in supplementary
The cell lines were additionally authenticated by FACS using cell-specific surface markers and cultured in a humidified 5% CO2 incubator.
Monoclonal PD-1 (EH122H7), PDL-1 (clone 29E2A3), TIGIT (clone A15152G), LAG3 (clone 7H2C65), CD62L (clone DREG-56), CD45RO (clone UCHL1), CD4 (clone RPA-T4) and CD8 (clone RPA-T8) antibodies antibodies were from Biolegend. PLAP antibody (clone H17E2) was obtained from Thermo Fisher. Other antibodies were described in [30].
The second generation CAR with CD8 alpha signaling peptide, PLAP Ab ScFv [21], CD8 hinge, CD28 co-stimulatory domain and CD3 activation domain was cloned down-stream of EF1 promoter into modified lentiviral vector pCD510 (Systems Bioscience). The same construct was generated with humanized PLAP ScFv (called humanized PLAP or PLAPh2, h4 (clone 2 or 4), and Mock control with either ScFv of intracellular protein or Mock control with 45 amino-acid sequence containing three epitopes of transferrin antibody, called (Mock-CAR). The mouse PLAP-CAR was generated by Synbio. The humanized PLAP ScFv sequences was synthesized by IDT as gBlock sequence with Nhe I and Xho I restriction sites flanking ScFv, and sub-cloned into these sites in lentiviral vector between CD8 alpha signaling peptide and CD8 hinge sequences.
Humanization of PLAP was performed as described in [31]. The human frames from human antibody clones with highest homology were used for humanized pairs using bioinformatics in silico methods as described [32,33]. Mouse CDR were inserted into these clones and different humanized ScFv variants were used for generating CAR constructs and performing CAR-T cell functional tests.
The lentiviral CAR constructs were used for generation of lentivirus by transfecting 293 FT cells using transfection agent (Alstem) and Lentivirus Packaging Mix as described [34]. The lentiviral titers in pfu/ml were detected by RT-PCR using the Lenti-X qRT-PCR kit (Takara) according to the manufacturer's protocol and the 7900HT thermal cycler (Thermo Fisher).
Transduction with CAR Lentivirus and CAR-T Cell Expansion
PBMC were resuspended at 1×106 cells/ml in AIM V-AlbuMAX medium (Thermo Fisher) containing 10% FBS with 300 U/ml IL-2 (Thermo Fisher). PBMC were activated with CD3/CD28 Dynabeads (Invitrogen), and cultured in 24-well plates. CAR lentivirus was added to the PBMC cultures at 24 and 48 hours using TransPlus transduction enhancer (AlStern), as described [30,31,34]. The CAR-T cells were cultured and expanded for 14 days by adding fresh medium to maintain the cell density at 1×106 cells/ml.
To detect CAR expression, 5×105 cells were suspended in 1×PBS plus 0.5% BSA buffer and incubated on ice with human serum (Jackson Immunoresearch, West Grove, Pa.) for 10 min. Then allophycocyanin (APC)-labeled anti-CD3 (eBioscience, San Diego, Calif.), 7-aminoactinomycin D (7-AAD, BioLegend, San Diego, Calif.), anti-F(ab)2 or its isotype control were added, and the cells were incubated on ice for 30 min. Then cells were rinsed with buffer, and analyzed on a FACSCalibur (BD Biosciences) first for light scatter versus 7-AAD staining, then the 7-AAD-negative live gated cells were plotted for CD3 staining versus F(ab)2 staining or isotype control staining. For FACS with colon cancer cell lines to detect PLAP levels mouse monoclonal PLAP antibody (H17E2) from Ximbio (London, UK) was used, and analysis was performed on FACSCalibur.
The binding of PLAP antibody with recombinant PLAP extracellular domain protein from Sino Biological was performed using Blitz ForteBio system as described [30]. In brief, anti-mouse-capture (AMC) biosensors were soaked in kinetics buffer (PBS, 0.1% Tween, 0.05% BSA) for 10 min and then with mouse anti-PLAP antibody at 0.1 mg/mL in same buffer for 30 min. After washing, biosensors were used to bind the PLAP antigen at different concentrations. The Kd was detected with Blitz system software.
Adherent colon cancer target cells (10,000 cells per well) were seeded into 96-well E-plates (Acea Biosciences, San Diego, Calif.) and cultured overnight using the impedance-based real-time cell analysis (RTCA) iCELLigence system (Acea Biosciences). After 20-24 hours, the medium was replaced with 1×105 effector cells (CAR-T cells, Mock CAR-T cells or non-transduced T cells) in AIM V-AlbuMAX medium containing 10% FBS, in triplicate. In some experiments checkpoint protein antibodies PD-1, LAG-3 or isotype at 10 μg/ml were added to the effector cells either alone or in combination with CAR-T cells. In some series of experiments target cells were pre-treated with 20 ng/ml of IFN-γ for 24 h. The cells were monitored for 1-2 days with the RTCA system, and impedance (proportional to cell index) was plotted over time. Cytotoxicity was calculated as (impedance of target cells without effector cells—impedance of target cells with effector cells)×100/impedance of target cells without effector cells.
The target cells were cultured with the effector cells (CAR-T cells or non-transduced T cells) at in U-bottom 96-well plates with AIM V-AlbuMAX medium plus 10% FBS, in triplicate. After 16 h the supernatant was removed and centrifuged to remove residual cells. In some experiments, supernatant after RTCA assay was used for ELISA cytokine assays. The supernatant was transferred to a new 96-well plate and analyzed by ELISA for human cytokines using kits from Thermo Fisher according to the manufacturer's protocol.
Six-week old male NSG mice (Jackson Laboratories, Bar Harbor, Me.) were housed in accordance with the Institutional Animal Care and Use Committee (IACUC) protocol. Each mouse was injected subcutaneously with 2×106 colon cancer cells in sterile 1×PBS. The CAR-T cells (1×107 CAR-T cells/mice) were injected intravenously into mice at days 1, 7 and 13. Tumor sizes were measured with calipers twice-weekly and tumor volume (in mm3) was determined using the formula W2L/2, where W is tumor width and L is tumor length. At the end 0.1 ml of blood was collected and used for analysis of toxicology markers.
Mouse serum samples were processed with clinical chemistry analyzer (Beckman-Coulter AU680) by IDEX Bioanalytics (West Sacramento, Calif.) for detection levels of toxicology markers: ALT (alanine aminotransferase), AST (aspartate aminotransferase), amylase in U/ml.
Samples with different types of normal tissues or tumor tissues were obtained from archived slides of Promab (Richmond, Calif.). The TMA slide with 106 primary colon cancer adenocarcinoma was obtained from Biomax (Rockville, Md.) and used for IHC with PLAP antibody.
The primary tumor tissue or normal tissue section slides or primary TMA slides were incubated in xylene twice for 10 min, then hydrated in alcohol and rinsed in 1×PBS. Heat-induced antigen retrieval was performed using a pressure cooker for 20 min in 10 mM citrate buffer, pH 6.0. The slides were rinsed with PBS, incubated in a 3% H2O2 solution for 10 min, then rinsed again with 1×PBS, and incubated in goat serum for 20 min. The tissue section slides were incubated with mouse monoclonal PLAP (H17E2) primary antibody overnight at 4° C. or 1.5 hours at 37° C. The slides were rinsed 3 times with PBS, incubated with biotin-conjugated secondary antibody for 10 min, rinsed with PBS, incubated with streptavidin-conjugated peroxidase for 10 min, and rinsed 3 times with 1×PBS buffer. The slides were incubated in DAB substrate solution for 2-5 min under the microscope. The reaction was stopped by washing in water, counterstained with hematoxylin, rinsed with water, and dehydrated in 75%, 80%, 95% and 100% ethanol and xylene. For negative control isotype antibody was used, and for positive control placenta samples were used. Images were acquired on the Motic DMB5-2231PL microscope using Images Plus 2.0. software (Motic, Xiamen, China). PLAP expression correlation with survival free prognosis was performed using R2 Genomics Analysis and Visualization platform (http://r2platform.com/http://r2.amc.n1).
The CAR structures were: Human CD8 signaling peptide, mouse scFv or humanized derived from antibody H17E2 (VH-Linker-3x(GGGGS)-VL), CD8 hinge, CD28 transmembrane, co-activation domain, CD3 zeta activation domain (
SEQ ID NO: 3 (Mouse PLAP CAR, called PMC262), starting with ATG and ending with a stop codon TAA (underlined), signaling peptide is in bold, VH with CDRs 1, 2, 3, bold underlined; linker in italics, VL with CDR 1,2,3 in bold, underlined); ScFV is flanked by 5′ Nhe and 3′ Xho sites, small font
ATGGCCTTACCAGTGACCGCCTTGCTCCTGCCGCTGGCCTTGCTGCTCCA
TCATTAACCAGTTATGGTGTAAGC
TGGGTTCGCCAGCCTCCAAGAAAGGG
CAGCTCTCATATCC
AGACTGAGCATCAACAAGGATAACTCCAAGAGCCAA
GAC ATC CAG ATG ACT CAG TCT CCA GCC TCC CTA ACT
GCA TCT GTG GGA GAA ACT GTC ACCATC ACC TGT CGA
GCA AGT GAA AAT ATT TAC AGT TAT
GTA GCA
TGG TAT
CAG CAG AAA CAGGGA AAA TCT CCT CAG TTC CTG GTC
TAT
AAT GCA AAA TCC TTA GCA
GAG GGT GTG CCA
TCAAGG TTC AGT GGC AGY GGA TCA GGC ACA CAG TTT
TCT CTG AAG ATC AAC AGC CTG CAG CCTGAA GAT TTT
GGG AAT TAT TAC TGT
CAA CAT CAT TAT GTT AGT CCG
TGG
ACG TTC GGT GGAGGC ACC AAG CTG GAA ATC AGA
CGG ctcgagAAGCCCACCACGACGCCAGCGCCGCGACCACCAACACCGG
SEQ ID NO: 5 is the amino acid sequence of SEQ ID NO: 3 (mouse PLAP-CD28-CD3zeta CAR): signaling peptide-VH-linker (in italics smaller font GSSSSx3)-VL-h-CD28−CD3. Sequence in bold is mouse PLAP scFv; CDR 1,2,3 underlined; VH-linker in italics-VL.
Q L K E S G P G L V A P S Q S L S I T C T V S G
F
S L T S Y G V S
W V R Q P P R K G L E W L G
V I W
E D G S T N Y H S A L I S
R L S I N K D N S K S Q
V F L K L N S L Q T D D T A T Y Y C A K
P H Y G S
S Y V G A M E Y
W G Q G T S V T V S S
D I Q M T Q S P A S
L T A S V G E T V T I T C
R A S E N I Y S Y V A
W
Y Q Q K Q G K S P Q F L V Y
N A K S L A
E G V P S
R F S G X G S G T Q F S L K I N S L Q P E D F G N
Y Y C
Q H H Y V S P W
T F G G G T K L E I R R L E
Q V Q L K E S G P G L V A P S Q S L S I T C T V S
G
F S L T S Y G V S
W V R Q P P R K G L E W L G
V
I W E D G S T N Y H S A L I S
R L S I N K D N S K
S Q V F L K L N S L Q T D D T A T Y Y C A K
P H Y
G S S Y V G A M E Y
W G Q G T S V T V S S
D I Q M T Q S P A S L T A S V G E T V T I T C
R A
S E N I Y S Y V A
W Y Q Q K Q G K S P Q F L V Y
N
A K S L A
E G V P S R F S G X G S G T Q F S L K I
N S L Q P E D F G N Y Y C
Q H H Y V S P W
T F G G
G T K L E I R R
Q V Q L K E S G P G L V A P S Q S L S I T C T V S
G
F S L T S Y G V S
W V R Q P P R K G L E W L G
V
I W E D G S T N Y H S A L I S
R L S I N K D N S K
S Q V F L K L N S L Q T D D T A T Y Y C A K
P H Y
G S S Y V G A M E Y
W G Q G T S V T V S S
D I Q M T Q S P A S L T A S
V G E T V T I T C
R A S E N I Y S Y V A
W Y Q Q K
Q G K S P Q F L V Y
N A K S L A
E G V P S R F S G
X G S G T Q F S L K I N S L Q P E D F G N Y Y C
Q
H H Y V S P W
T F G G G T K L E I R R
The scheme of CAR construct is shown below, which shows the sub-domain sequences of SEQ ID NO: 3.
ATGGCCTTACCAGTGACCGCCTTGCTCCTGCCGCTGGCCTTGCTGCTCCA
ATGGCCTTACCAGTGACCGCCTTGCTCCTGCCGCTGGCCTTGCTGCTCCA
TCATTAACCAGTTATGGTGTAAGC
TGGGTTCGCCAGCCTCCAAGAAAGGG
CAGCTCTCATATCC
AGACTGAGCATCAACAAGGATAACTCCAAGAGCCAA
GAC ATC CAG ATG ACT CAG TCT CCA GCC TCC CTA ACT
GCA TCT GTG GGA GAA ACT GTC ACCATC ACC TGT
CGA GCA
AGT GAA AAT ATT TAC AGT TAT GTA GCA
TGG TAT CAG
CAG AAA CAGGGA AAA TCT CCT CAG TTC CTG GTC TAT
AAT
GCA AAA TCC TTA GCA
GAG GGT GTG CCA TCAAGG TTC AGT
GGC AGY GGA TCA GGC ACA CAG TTT TCT CTG AAG ATC
AAC AGC CTG CAG CCTGAA GAT TTT GGG AAT TAT TAC TGT
CAA CAT CAT TAT GTT AGT CCG TGG
ACG TTC GGT GGAGGC
ACC AAG CTG GAA ATC AGA CGG
SEQ ID NO: 14 (human h1 PLAP CAR), starting with ATG and ending with a stop codon TAA (underlined). The sequence starts with a signaling peptide, then the humanized PLAP scFv h1. The nucleotide sequence has the same structure as SEQ ID NO: 2 except the scFv portion. The bold sequence is humanized h1 PLAP-1 scFv (CDRs 1, 2, 3 are underlined). Different nucleotides in humanized frame regions compared with mouse are underlined but not bolded.
ATGGCCTTACCAGTGACCGCCTTGCTCCTGCCGCTGGCCTTGCTGCTCCA
T
T
GTG
A
GACC
TAGC
CAGACCCT
GAG
C
C
T
G
AC
C
TGCAC
C
GT
G
TC
T
GG
C
TTC
A
C
CTTCACCAGTTATGGTGTAAGC
TGGGT
GA
G
A
CAGCC
A
CC
TG
GA
CGA
GG
TCT
T
GAGTGG
A
T
T
GGA
GTAATATGGGAAGACGGGAGCACAAATTATCATT
CAGCTCTCATATCC
AGA
G
TGA
CA
AT
GCTGGTA
GA
C
A
C
C
AG
CAAGAACCA
G
T
T
CAG
C
C
T
G
A
G
ACT
C
A
G
CAG
CG
TG
ACA
GC
C
G
CC
GACAC
C
GC
GGTC
TA
T
TA
T
TGTGCAAGACCCCACTACGGTAGCAGCTACGTGGGGGCTATGGAATACT
GGGGTCAAGG
C
A
G
CCTCGTCACAGTCTCCTCA
GTA GCA
TGG TAC CAG CAG AAG
CCA GGT AAG GCT CCA AAG CTG CTG ATC TAC AAT GCA
AAA TCC TTA GCA
GAG GGT GTG CCA AGC
CCA GAG GAC ATC GCC ACC TAC TAC TGC CAA CAT CAT
TAT GTT AGT CCG TGG
ACG TTC GGC CAA
SEQ ID NO: 15 is humanized h1 PLAP-1 CAR amino-acid sequence; it has the same structure as mouse PLAP-CAR except the scFv portion; sequence in bold is humanized h1 PLAP-1 ScFv, CDR 1, 2, 3 are in italics and underlined; linker are in a smaller font; different amino-acids in CDR regions in regular font; different amino-acids from mouse sequence in frame region are underlined.
Q L
Q
E S G P G L V
R
P S Q
T
L S
L
T C T V S
W V R Q P P G R G L E W I G
R V T M L V D T S K N Q F S L R L S S V T
A A
D T A
V
Y Y C A
W G Q G
S L
V T V S S
D I Q M T Q S P
S
S L S A S V G
D R
V T I T C
A W Y Q Q K P G K A P K L L I Y
E G V P S R F S G S G S G T D F T F T
I
S
S L Q P E D
I A T
Y C T F G Q G
T Y K
V
E I
K
R L E K P T T T P A P R P P T P A P
T F
V S W V R Q P P G R G L E W I G V
N Y H S A L I S R V T M L V D T S K
N Q F S L R L S S V T A A D T A V Y Y C
W G Q G S L V T V S S
D I Q M T Q S P S S L S A S V G D R V T I T C R A
S V A W Y Q Q K P G K A P K L L I Y N
S S L Q P E D I A T Y Y C G Q
G T K V E I K R
Q V Q L Q E S G P G L V R P S Q T L S L T C T V S
T F
V S W V R Q P P G R G L E W I G V
N Y H S A L I S R V T M L V D T S K
N Q F S L R L S S V T A A D T A V Y Y C A R
W G Q G S L V T V S S
D I Q M T Q S P S S
L S A S V G D R V T I T C R A S V A W
Y Q Q K P G K A P K L L I Y N A K S L A E G V P S
R F S G S G S G T D F T F T I S S L Q P E D I A T
Y Y C G Q G T K V E I K R
The bioinformatics approach was performed to generate additional humanized versions of PLAP CAR. The sequences were codon-optimized for higher expression of CAR.
The sequence starts with a signaling peptide (underlined, codon optimized), then the humanized PLAP scFv (bold). The nucleotide sequence has the same structure as SEQ ID NO: 3, except the scFv portion. The bold sequence is humanized PLAP-h2 (PMC409) scFv, the rest is same structure as mouse PLAP-CAR (SEQ ID NO: 5).
ATGGCCTTACCAGTGACCGCCTTGCTCCTGCCGCTGGCCTTGCTGCTCCA
CGCCGCCAGGCCGgctagc
CAG GTG CAG CTT CAG GAA AGT GGA CCG GGC CTT GTC
AAA CCG TCA GAG ACC CTT TCA CTG ACT TGC ACTGTA AGT
GGT TTC TCC CTG ACA AGC TAC GGA GTC TCC TGG ATA
CGC CAG CCA GCG GGG AAA GGG CTT GAGTGG ATC GGT GTG
ATC TGG GAA GAC GGG AGT ACA AAC TAT CAC TCA GCA
CTC ATT AGT CGA GTA ACA ATGTCC GTT GAC ACT TCC AAG
AAT CAA TTC AGT TTG AAA CTG TCT AGT GTG ACG GCT
GCG GAT ACA GCG GTTTAT TAC TGT GCC AGG CCT CAT TAC
GGA AGT TCT TAT GTT GGT GCA ATG GAG TAT TGG GGA
GCC GGC ACAACT GTC ACT GTG AGC TCC GGC GGG GGC GGA
AGT GGG GGA GGA GGC TCA GGC GGA GGT GGA AGT GAT
ATACAG ATG ACC CAG AGT CCT AGC TCA CTC TCT GCG TCC
GTA GGG GAC CGG GTA ACC ATC ACA TGC CGC GCCAGC GAG
AAT ATA TAC AGT TAC GTT GCA TGG TAC CAG CAA AAA
CCT GGC AAG GCG CCG AAG CTG TTG ATCTAC AAC GCC AAA
AGT CTC GCT TCC GGG GTC CCC AGC CGA TTT TCT GGC
TCA GGT AGT GGC ACA GAT TTCACA CTC ACA ATA AGC TCT
CTC CAG CCC GAA GAC TTT GCG ACG TAC TAC TGC CAG
CAT CAT TAT GTT AGTCCT TGG ACG TTT GGC GGA GGC ACA
AAA TTG GAA ATA AAA
The humanized PLAP h2 CAR amino-acid sequence is shown in SEQ ID NO: 20. It has the same structure as Mouse PLAP-CAR except the scFv portion; sequence in bold is humanized PLAP ScFV consisting from VL-linker-VL.
Q L Q E S G P G L V K P S E T L S L T C T V S G F
S L T S Y G V S W I R Q P A G K G L E W I G V I W
E D G S T N Y H S A L I S R V T M S V D T S K N Q
F S L K L S S V T A A D T A V Y Y C A R P H Y G S
S Y V G A M E Y W G A G T T V T V S S G G G G S G
G G G S G G G G S D I Q M T Q S P S S L S A S V G
D R V T I T C R A S E N I Y S Y V A W Y Q Q K P G
S G T D F T L T I S S L Q P E D F A T Y Y C Q H H
Y V S P W T F G G G T K L E I K L E K P T T T P A
Q V Q L Q E S G P G L V K P S E T L S L T C T V S
G F S L T S Y G V S W I R Q P A G K G L E W I G V
I W E D G S T N Y H S A L I S R V T M S V D T S K
N Q F S L K L S S V T A A D T A V Y Y C A R P H Y
G S S Y V G A M E Y W G A G T T V T V S S
DIQMTQSPSSLSASVGDRVTITC
RASENIYSYVA
WYQQKPGKAPKLLIY
N
AKSLA
SGVPSRFSGSGSGTDFTLTISSLQPEDFATYYC
QHHYVSPW
TFGG
GTKLEIK
Q V Q L Q E S G P G L V K P S E T L S L T C T V S
G F S L T S Y G V S W I R Q P A G K G L E W I G V
I W E D G S T N Y H S A L I S R V T M S V D T S K
N Q F S L K L S S V T A A D T A V Y Y C A R P H Y
G S S Y V G A M E Y W G A G T T V T V S S G G G G
S G G G G S G G G G S D I Q M T Q S P S S L S A S
V G D R V T I T C R A S E N I Y S Y V A W Y Q Q K
P G K A P K L L I Y N A K S L A S G V P S R F S G
S G S G T D F T L T I S S L Q P E D F A T Y Y C Q
H H Y V S P W T F G G G T K L E I K
The humanized PLAP h4 CAR (PMC410) codon optimized nucleotide sequence starts with a signaling peptide (underlined, SEQ ID NO: 9, codon optimized), then the humanized PLAP scFv (bold). The bold sequence is humanized PLAP-h4 (PMC410) scFv,
ATGGCCTTACCAGTGACCGCCTTGCTCCTGCCGCTGGCCTTGCTGCTCCA
CGCCGCCAGGCCGgctagc
CAG GTT CAA CTT CAA GAA TCA GGA CCG GGC TTG GTT
AAA CCT TCC GAA ACT CTG AGC CTT ACT TGT ACAGTG TCT
GGT GGA TCT ATT ACG AGC TAC GGA GTA AGT TGG ATC
CGG CAA CCA CCC GGG AAA GGG CTC GAATGG ATA GGG GTG
ATA TGG GAG GAT GGT TCA ACC AAC TAC CAT AGC GCT
CTG ATC AGC CGG GTG ACC ATTAGT GTC GAC ACT TCC AAA
AAC CAG TTT TCA TTG AAG CTC TCA AGC GTA ACT GCG
GCG GAT ACC GCC GTATAC TAT TGT GCG CGG CCA CAT TAC
GGG TCC TCT TAT GTT GGG GCG ATG GAA TAT TGG GGG
GCA GGT ACAACG GTC ACG GTG TCT TCA GGA GGA GGA GGG
TCA GGT GGT GGT GGT TCA GGA GGC GGG GGT AGC GAC
ATACAG ATG ACT CAA AGC CCC TCT TCA CTG TCT GCA TCA
GTC GGG GAC AGA GTC ACA ATA ACC TGC AGA GCGAGC GAG
AAT ATC TAC TCT TAT GTA GCC TGG TAT CAG CAA AAA
CCC GGC AAG GCG CCG AAA TTG CTC ATCTAT AAT GCG AAA
TCC TTG GCC AGT GGG GTC CCA TCA CGG TTC AGT GGC
TCC GGC TCT GGA ACC GAT TTCACA CTC ACA ATC TCT AGC
CTC CAG CCC GAA GAC TTC GCC ACA TAC TAT TGC CAA
CAT CAC TAT GTC AGCCCA TGG ACA TTT GGG GGA GGT ACG
AAA CTT GAA ATT AAA
Q L Q E S G P G L V K P S E T L S L T C T V S G G
S I T S Y G V S W I R Q P P G K G L E W I G V I W
E D G S T N Y H S A L I S R V T I S V D T S K N Q
F S L K L S S V T A A D T A V Y Y C A R P H Y G S
S Y V G A M E Y W G A G T T V T V S S G G G G S G
G G G S G G G G S D I Q M T Q S P S S L S A S V G
D R V T I T C R A S E N I Y S Y V A W Y Q Q K P G
K A P K L L I Y N A K S L A S G V P S R F S G S G
S G T D F T L T I S S L Q P E D F A T Y Y C Q H H
Y V S P W T F G G G T K L E I K L E K P T T T P A
Q V Q L Q E S G P G L V K P S E T L S L T C T V S
G V S W I R Q P P G K G L E W I G V
I W E D G S T N Y H S A L I
S R V T I S V D T S K
N Q F S L K L S S V T A A D T A V Y Y C A R
P H Y
G S S Y V G A M E Y
W G A G T T V T V S S
ATGGCCTTACCAGTGACCGCCTTGCTCCTGCCGCTGGCCTTGCTGCTCCA
CGCCGCCAGGCCGgctagc
CAG GTT CAA TTG CAA GAA TCA GGC CCT GGG CTT GTT
AAG CCG TCA GAG ACG CTT TCA CTG ACC TGT ACCGTG AGC
GGG TTC AGC CTC ACT TCC TAT GGT GTT TCT TGG ATA
CGA CAA CCA CCC GGA AAG GGC CTG GAATGG ATC GGG GTC
ATT TGG GAA GAT GGA TCC ACA AAC TAC AAT CCT TCA
CTT AAA TCC CGA GTT ACT ATCTCT GTT GAC ACC AGT AAA
AAT CAA TTC AGT CTC AAA CTG TCC AGT GTG ACA GCC
GCC GAC ACA GCA GTCTAC TAT TGC GCT CGC CCA CAT TAC
GGC TCC AGC TAC GTT GGG GCG ATG GAA TAT TGG GGA
GCT GGT ACCACA GTC ACG GTT AGT AGT GGA GGA GGT GGT
TCC GGG GGA GGG GGG AGC GGC GGA GGT GGA TCT GAT
ATCCAG ATG ACT CAG TCT CCA AGT TCC CTT TCT GCA AGC
GTA GGT GAT CGA GTC ACT ATC ACA TGC AGG GCGTCC GAG
AAC ATA TAC AGT TAT GTT GCA TGG TAC CAA CAG AAG
CCA GGT AAA GCG CCT AAG CTG CTT ATTTAT AAC GCT AAA
TCT CTT GCT TCT GGG GTA CCA TCC CGA TTC TCA GGG
TCT GGA AGT GGC ACT GAT TTCACG TTG ACT ATT TCC TCC
CTT CAA CCG GAG GAT TTT GCA ACG TAC TAC TGT CAG
CAT CAT TAT GTC AGCCCG TGG ACG TTC GGT GGC GGC ACG
AAA CTT GAG ATT AAA
Q L Q E S G P G L V K P S E T L S L T C T V S G F
S L T S Y G V S W I R Q P P G K G L E W I G V I W
E D G S T N Y N P S L K S R V T I S V D T S K N Q
F S L K L S S V T A A D T A V Y Y C A R P H Y G S
S Y V G A ME Y W G A G T T V T V S S G G G G S G G
G G S G G G G S D I Q M T Q S P S S L S A S V G D
R V T I T C R A S E N I Y S Y V A W Y Q Q K P G K
A P K L L I Y N A K S L A S G V P S R F S G S G S
G T D F T L T I S S L Q P E D F A T Y Y C Q H H Y
V S P W T F G G G T K L E I K L E K P T T T P A P
Q V Q L Q E S G P G L V K P S E T L S L T C T V S
G
F S L T S Y G V S
W I R Q P P G K G L E W I G
R V T I S V D T S
K N Q F S L K L S S V T A A D T A V Y Y C A R
P H
Y G S S Y V G A ME Y
W G A G T T V T V S S
QVQLQESGPGLVKPSETLSLTCTVSG
VSWIRQPPGKGLE
RVTISVDTSKNQFSLKLSSVTAADTAVYYCA
R
PHYGSSYVGAMEY
WGAGTTVTVSS
Q V Q L Q E S G P G L V K P S E T L S L T C T V S
G G S I T S Y G V S W I R Q P P G K G L E W I G V
I W E D G S T N Y N P S L K S R V T I S V D T S K
N Q F S L K L S S V T A A D T A V Y Y C A R P H Y
G S S Y V G A M E Y W G A G T T V T V S S G G G G
S G G G G S G G G G S D I Q M T Q S P S S L S A S
V G D R V T I T C R A S E N I Y S Y V A W Y Q Q K
P G K A P K L L I Y N A K S L A S G V P S R F S G
S G S G T D F T L T I S S L Q P E D F A T Y Y C Q
H H Y V S P W T F G G G T K L E I K
We performed IHC staining with PLAP antibody on placenta, testis, colon cancer, ovarian cancer and other normal or malignant tissues from different types of cancer. Placenta had highest staining, testis, colon and ovarian cancer were positive, while other type of cancer (breast, lung, prostate cancer) were negative as well as normal tissues: pancreas, tonsil, rectum, muscle, esophagus, brain and other tissues. In addition, we evaluated mRNA expression of PLAP expression in silico across 1457 different malignant cell lines, including 63 colon cancer cell lines using the Cancer Cell Line Encyclopedia (CCLE). Expression of PLAP was high in gastro-intestinal (GI) cancers: cancers of esophagus, upper aerodigestive organs, stomach, pancreatic and colon cancers. We also performed analysis using Genotype-Tissue Expression (GTEx) database of PLAP expression in nonmalignant normal tissues. PLAP mRNA had minimal expression in many normal tissues (many had 0 TMP (transcript per million kb) mRNA level. In contrast when we analyzed EpCAM as a positive control, its expression was medium-high in many normal tissues with medium expression in colon 445 TMP (transcript per million kb), small intestine 391 and in thyroid 259. Thus, PLAP has negative expression in most normal tissues in contrast to other tumor-associated markers.
We performed IHC staining with mouse PLAP antibody using 106 primary colon cancer tumors, and found PLAP expression in 25 of 106 samples that is 23.8% of all colon cancer tumors. We also tested PLAP expression by R2 genomics analysis and visualization platform in 557 primary colon cancer tumors and performed correlation with patient outcome (
In addition, we tested PLAP mRNA level in 117 colon cancer cell lines using microarray assay, and detected that 21.3% of colon cancer cell lines expressed PLAP mRNA. We performed FACS assay and detected PLAP in colon cancer cell lines with high PLAP mRNA expression: Lovo, Caco-2 and LS123 cell lines (
We designed second generation CAR construct using mouse monoclonal PLAP antibody ScFv, CD8 alpha hinge, CD28 transmembrane and co-stimulatory domain and CD3 activation domain (
PLAP-CAR-T cells were used in a Real-time cytotoxicity assay (RTCA) with PLAP-positive target colon cancer cell lines: Lovo, and LS-123; and with PLAP-negative colon cancer cell lines: HT29, and HCT116. PLAP-CAR-T cells had significant killing activity compared with normal T cells against Lovo and LS-123 colon cancer target cells but did not have significant killing activity with PLAP-negative HCT116 and HT29 colon cancer cell lines (
To improve mPLAP-CAR-T cells, we humanized mouse PLAP ScFv, and generated humanized PLAP-CAR cells (
PLAP-CAR-T cells (h2 and h4) significantly killed PLAP-positive cells compared to Mock control CAR-T cells and did not kill significantly PLAP-negative cells in RTCA assay (
We analyzed PLAP-CAR-T cell efficacy in Lovo xenograft mouse model in vivo (
To test toxicity of CAR-T cells, we performed analysis of several enzymes from mouse blood serum: AST, ALT and amylase (
Real-time cytotoxicity assay (RCTA) and IFN-γ assay were performed according to Example 1.
These data show that humanized PLAP h5-CAR-T cells specifically and effectively killed PLAP-positive colon cancer cells and specifically secreted IFN-gamma against PLAP-positive colon cancer cell line.
We tested expression of PDL-1 on colon cancer target cells in response to hPLAP-CAR-T cells when we co-cultured them for 24 hours (
Since Lovo cells activated PDL-1 significantly more in response to PLAP-CAR-T cells than in response to IFN-gamma (
To evaluate up-regulation of checkpoint proteins in CAR-T cells after co-incubation with colon cancer cells, we tested several checkpoint proteins: PD-1, TIM-3, TIGIT and LAG-3. Only PD-1 was significantly up-regulated in CAR-T cells after co-culture with PALP-positive colon cancer target cells than before co-culture (
To test checkpoint inhibitors in combination with PLAP-CAR-T cells, we used PLAP-h2-CAR-T cells in combination with either PD-1 antibody or LAG-3 antibody and performed RTCA assay with Lovo target cells (
This application is a continuation of PCT/US2019/033953, filed May 24, 2019; which claims the priority of U.S. Provisional Applications No. 62/683,999, filed Jun. 12, 2018, and 62/792,344, filed Jan. 14, 2019. The contents of the above-identified applications are incorporated herein by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 62683999 | Jun 2018 | US | |
| 62792344 | Jan 2019 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2019/033953 | May 2019 | US |
| Child | 17115591 | US |
