EP4284824A2

EP4284824A2 - Chimeric antigen receptors targeting cd20

Info

Publication number: EP4284824A2
Application number: EP22746521.8A
Authority: EP
Inventors: Yihong Yao; Jiaqi Huang; Xin Yao
Original assignee: Cellular Biomedicine Group Inc
Current assignee: Cellular Biomedicine Group Inc
Priority date: 2021-01-27
Filing date: 2022-01-26
Publication date: 2023-12-06
Also published as: WO2022164886A2; WO2022164886A3

Abstract

Chimeric antigen receptors targeting CD20 and preparation methods thereof are provided. The antigen binding region of the chimeric antigen receptor may include a heavy chain variable region shown in SEQ ID NOs: 7, 9 or 33 and a light chain variable region shown in SEQ ID NOs: 11, 13 or 35.

Description

CHIMERIC ANTIGEN RECEPTORS TARGETING CD20 CROSS REFERENCE TO RELATED APPLICATIONS The present application claims priority to U.S. Provisional Application Nos.63/142,216 (filed on January 27, 2021), and 63/154,040 (filed on February 26, 2021), and U.S. application No.17/352,915 (filed on June 21, 2021), each of which is hereby incorporated by reference in its entirety. SEQUENCE LISTING This application contains a Sequence Listing which has been filed electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on January 26, 2022, is named 11299-008883-WO1_ST25.txt and is 73 KB in size. TECHNICAL FIELD The present disclosure provides chimeric antigen receptors targeting the CD20 antigen, and a preparation method for modified T cells (CAR-T cells) and activity identification thereof. The present disclosure provides chimeric antigen receptors for treating CD20-positive diseases such as B cell lymphoma. BACKGROUND Malignant tumors of the blood system account for about 10% of human malignant tumors, and 95% of malignant tumors of the blood system are derived from B lymphocytes. Traditional chemotherapy and radiotherapy play an important role in the treatment of malignant tumors of the blood system. Some patients have seen significant effects, but most of them are difficult to cure. New and effective treatments are urgently needed. Adoptive T cell therapy has shown its powerful efficacy and bright prospect in the clinical treatment of malignant tumors. Among them, multiple centers independently using chimeric antigen receptor (CAR)-modified T cells to target recurrent, refractory malignant tumors of CD19-expressed B cell have achieved unprecedented success. In particular, in a clinical trial carried out at the School of Medicine, University of Pennsylvania using CART19 in the treatment of recurrent, refractory acute B-cell lymphoma (R/R B-ALL), up to 94% of patients achieved complete remission. Although the initial response rate of this clinical trial was high, nearly 40% of patients who achieved complete response after 1 month of treatment, had a relapse, and more than 60% of patients with relapse had CD19-negative tumor cells escape. Therefore, there is an urgent need to identify CARs that target B cell lymphoma-associated antigens other than CD19 to treat patients with malignant lymphoma. CD20 is a glycosylated protein and is the first identified B cell membrane marker. CD20 is also known as B1, and encoded by the MS4A gene. CD20 molecule has four transmembrane hydrophobic regions, and its N-terminal and C-terminal are located on the cytoplasmic side, thereby forming two closed loops outside the cell, which are respectively called big loop and small loop. CD20 is specifically expressed in more than 95% of normal and cancerous B cells. These cells are in the pre-B cell stage and subsequent developmental stages, and CD20 stops expression until the cells differentiated into plasma cells. Therefore, CD20 is an ideal target for immunotherapy of B cell malignancies. Rituximab (MabThera®, Rituxan®) is the first generation of chimeric monoclonal antibody targeting CD20 which was firstly approved by the US FDA and the European EMA for treating indolent lymphoma. Rituximab recognizes and binds to the big loop structure of the extracellular domain of CD20, and it kills tumor cells by ADCC-mediated killing effect. However, Rituximab alone shows limited activity and short duration of response, but its combination with chemotherapy can significantly enhance the efficacy of chemotherapy. Rituximab is used for the treatment of lymphoma, and half of the patients have a complete response (CR) or a partial response (PR). Ofatumumab (Arzerra^®) is the first completely humanized CD20 therapeutic antibody. Unlike Rituximab, the epitope recognized by Ofatumumab contains parts of the big loop and the small loop of CD20. At the same time, the tumor killing method of Ofatumumab is mainly through the complement-dependent pathway, followed by ADCC-dependent tumor killing effect. Obinutuzumab (Gazyvaro^®, Gazyva^®) is a humanized type II CD20 antibody that reduces fucosylation levels and optimizes FcγRIIIa affinity. Obinutuzumab recognizes and binds to the big loop of the extracellular molecule of CD20, and mediates the killing effect on tumor mainly through the ADCC effect. At the same time, the binding of Obinutuzumab to CD20 molecule also has the effect of inducing apoptosis of tumor cells. As for the NHL that does not respond to Rituximab treatment, Obinutuzumab is combined with bendamustine, a nitrogen mustard drug. The phase III clinical trial found that the duration with no deterioration of combination therapy of Obinutuzumab and bendamustine was twice as long as that of bendamustine therapy alone (the former is 29 months and the latter is 14 months). Obinutuzumab has an overall response rate (ORR, including CR and PR) of 77.3%, and Rituximab is 65.7%. Compared with therapeutic antibodies, cellular immunotherapy is an emerging and highly effective tumor treatment model, and is a new type of autoimmunolgy treatment for cancer. It is a method for in vitro culture and amplification of immune cells collected from a patient using biotechnology and biological agents, and then the cells are transfused back to the patient to stimulate and enhance the body's autoimmune function, thereby achieving the purpose of treating tumors. The skilled in the art have been working to develop new cellular immunotherapy to increase its efficiency and reduce its side effects. Although many therapeutic antibodies as described above have been developed in these years, their clinical therapeutic effects have not reached the same level of therapeutic effects as CART19. Therefore, the development of CART therapy targeting CD20 has great market value and social significance.

SUMMARY The present disclosure provides for a chimeric antigen receptor (CAR), comprising: an anti-CD20 antigen-binding region which comprises a heavy chain variable region (V_H) and a light chain variable region (V_L), V_H comprising three CDRs, HCDR1, HCDR2 and HCDR3, V_L comprising three complementarity determining regions (CDRs), LCDR1, LCDR2 and LCDR3. In certain embodiments, HCDR1, HCDR2 and HCDR3 may have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43, respectively. LCDR1, LCDR2 and LCDR3 may have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 44, SEQ ID NO: 45, SEQ ID NO: 46, respectively. In certain embodiments, HCDR1, HCDR2 and HCDR3 may have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 48, SEQ ID NO: 50, SEQ ID NO: 52, respectively. LCDR1, LCDR2 and LCDR3 may have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 55, SEQ ID NO: 57, SEQ ID NO: 59, respectively. In certain embodiments, HCDR1, HCDR2 and HCDR3 may have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 62, SEQ ID NO: 64, SEQ ID NO: 66, respectively. LCDR1, LCDR2 and LCDR3 may have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 69, SEQ ID NO: 71, SEQ ID NO: 73, respectively. In certain embodiments, V_H is located at the N-terminus of V_L. In certain embodiments, V_L is located at the N-terminus of V_H. In certain embodiments, V_H and V_L have amino acid sequences about 80% to about 100% identical to amino acid sequences set forth in (a) SEQ ID NO: 7 and SEQ ID NO: 11, respectively; (b) SEQ ID NO: 9 and SEQ ID NO: 13, respectively; or (c) SEQ ID NO: 33 and SEQ ID NO: 35, respectively. In certain embodiments, the anti-CD20 antigen-binding region is a single-chain variable fragment (scFv) that specifically binds CD20. The CAR may further comprise one or more of the following: (a) a signal peptide, (b) a hinge region, (c) a transmembrane domain, (d) a co-stimulatory region, and (e) a cytoplasmic signaling domain. In certain embodiments, the co-stimulatory region comprises a co-stimulatory region of 4-1BB (CD137), CD28, or combinations thereof. In certain embodiments, the co-stimulatory region comprises an amino acid sequence about 80% to about 100% identical to the amino acid sequence set forth in SEQ ID NO: 23, or SEQ ID NO: 39. In certain embodiments, the cytoplasmic signaling domain comprises a cytoplasmic signaling domain of CD3ζ. In certain embodiments, the cytoplasmic signaling domain comprises an amino acid sequence about 80% to about 100% identical to the amino acid sequence set forth in SEQ ID NO: 25. In certain embodiments, the hinge region comprises a hinge region of CD8, CD28, CD137, IG4, or combinations thereof. In certain embodiments, the hinge region comprises an amino acid sequence about 80% to about 100% identical to the amino acid sequence set forth in SEQ ID NO: 17, or SEQ ID NO: 19. In certain embodiments, the transmembrane domain comprises a transmembrane domain of CD8, CD28, or combinations thereof. In certain embodiments, the transmembrane domain comprises an amino acid sequence about 80% to about 100% identical to the amino acid sequence set forth in SEQ ID NO: 21. In certain embodiments, the CAR comprises an amino acid sequence about 80% to about 100% identical to the amino acid sequence set forth in SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 29, or SEQ ID NO: 31. In one embodiment, the CAR comprises an amino acid sequence about 80% to about 100% identical to the amino acid sequence set forth in SEQ ID NO: 5. The present disclosure provides for an immune cell expressing or comprising the CAR. The immune cell may be a T cell or a natural killer (NK) cell. The present disclosure also provides for a nucleic acid encoding the CAR, or a vector comprising the nucleic acid. The present disclosure provides for a pharmaceutical composition comprising the immune cell, the nucleic acid, the vector, or the CAR. Also encompassed by the present disclosure is a method of treating cancer, the method comprising administering the immune cell to a subject in need thereof. The cancer may be a hematologic cancer. The cancer may be a B-cell malignancy. The B-cell malignancy may be acute lymphocytic leukemia (ALL), chronic lymphocytic leukemia (CLL), B-cell acute lymphoblastic leukemia (B-ALL), B-cell leukemia, or B cell lymphoma. The cancer may be Hodgkin's lymphoma, non-Hodgkin's lymphoma, leukemia, and/or multiple myeloma (MM). The immune cell may be administered by infusion, injection, transfusion, implantation, and/or transplantation. The immune cell may be administered intravenously, subcutaneously, intradermally, intranodally, intratumorally, intramedullary, intramuscularly, or intraperitoneally. The immune cell may be administered via intravenous infusion. The immune cell may be allogeneic or autologous. The subject may be a human. The present disclosure provides for a method for treating cancer. The method may comprise administering the immune cell to a subject in need thereof. The chimeric antigen receptor (CAR) may generate an area under the curve (AUC) ranging from about 1.0e+05 copies/µg genomic DNA (copies/gDNA) to about 1.1e+07 copies/gDNA, from about 2.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.1e+07 copies/gDNA, from about 1.0e+05 copies/µg genomic DNA (copies/gDNA) to about 4.0e+06 copies/gDNA, from about 1.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.0e+07 copies/gDNA, from about 5.0e+05 copies/µg genomic DNA (copies/gDNA) to about 1.3e+07 copies/gDNA, from about 5.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.0e+07 copies/gDNA, from about 5.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.3e+07 copies/gDNA, or from about 7.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.0e+07 copies/gDNA, in the blood of the subject in about 28 days after administration. Also encompassed by the present disclosure is a method for treating cancer, the method comprising administering the immune cell to a subject in need thereof. The chimeric antigen receptor (CAR) may generate a maximum plasma concentration (C_max) ranging from about 1.0e+04 copies/µg genomic DNA (copies/gDNA) to about 1.1e+06 copies/gDNA, from about 1.0e+04 copies/µg genomic DNA (copies/gDNA) to about 3.0e+05 copies/gDNA, from about 2.0e+05 copies/µg genomic DNA (copies/gDNA) to about 1.1e+06 copies/gDNA, from about 5x10⁴ copies/µg genomic DNA (copies/gDNA) to about 1.3x10⁶ copies/gDNA, from about 5x10⁵ copies/µg genomic DNA (copies/gDNA) to about 1.3x10⁶ copies/gDNA, or from about 7.5x10⁵ copies/µg genomic DNA (copies/gDNA) to about 1x10⁶ copies/gDNA, in the blood of the subject. The CAR may have a T_max ranging from about 10 days to about 25 days, from about 10 days to about 20 days, from about 12 days to about 15 days, from about 12 days to about 25 days, from about 14 days to about 20 days, or from about 6 days to about 22 days. In certain embodiments, the anti-CD20 antigen-binding region includes a heavy chain variable region (V_H) comprising an amino acid sequence at least or about 70%, at least or about 75%, at least or about 80%, at least or about 85%, at least or about 90%, at least or about 95%, at least or about 99%, at least or about 81%, at least or about 82%, at least or about 83%, at least or about 84%, at least or about 85%, at least or about 86%, at least or about 87%, at least or about 88%, at least or about 89%, at least or about 90%, at least or about 91%, at least or about 92%, at least or about 93%, at least or about 94%, at least or about 95%, at least or about 96%, at least or about 97%, at least or about 98%, at least or about 99%, or about 100% identical to the amino acid sequence set forth in SEQ ID NO: 7, SEQ ID NO: 9, or SEQ ID NO: 33. In certain embodiments, the anti-CD20 antigen-binding region includes a light chain variable region (V_L) comprising an amino acid sequence at least or about 70%, at least or about 75%, at least or about 80%, at least or about 85%, at least or about 90%, at least or about 95%, at least or about 99%, at least or about 81%, at least or about 82%, at least or about 83%, at least or about 84%, at least or about 85%, at least or about 86%, at least or about 87%, at least or about 88%, at least or about 89%, at least or about 90%, at least or about 91%, at least or about 92%, at least or about 93%, at least or about 94%, at least or about 95%, at least or about 96%, at least or about 97%, at least or about 98%, at least or about 99%, or about 100% identical to the amino acid sequence set forth in SEQ ID NO: 11, SEQ ID NO: 13, or SEQ ID NO: 35. A heavy chain variable region of the anti-CD20 antigen-binding region can comprise one, two, or three complementarity determining regions (CDRs) that are at least or about 70%, at least or about 75%, at least or about 80%, at least or about 85%, at least or about 90%, at least or about 95%, at least or about 99%, at least or about 81%, at least or about 82%, at least or about 83%, at least or about 84%, at least or about 85%, at least or about 86%, at least or about 87%, at least or about 88%, at least or about 89%, at least or about 90%, at least or about 91%, at least or about 92%, at least or about 93%, at least or about 94%, at least or about 95%, at least or about 96%, at least or about 97%, at least or about 98%, at least or about 99%, or about 100%, identical to the CDRs of a heavy chain variable region of the Ofatumumab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43, respectively), or the CDRs of a heavy chain variable region of the Rituximab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 48, SEQ ID NO: 50, SEQ ID NO: 52, respectively), or the CDRs of a heavy chain variable region of the Obinutuzumab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 62, SEQ ID NO: 64, SEQ ID NO: 66, respectively). A light chain variable region of the anti-CD20 antigen-binding region can comprise one, two, or three complementarity determining regions (CDRs) that are at least or about 70%, at least or about 75%, at least or about 80%, at least or about 85%, at least or about 90%, at least or about 95%, at least or about 99%, at least or about 81%, at least or about 82%, at least or about 83%, at least or about 84%, at least or about 85%, at least or about 86%, at least or about 87%, at least or about 88%, at least or about 89%, at least or about 90%, at least or about 91%, at least or about 92%, at least or about 93%, at least or about 94%, at least or about 95%, at least or about 96%, at least or about 97%, at least or about 98%, at least or about 99%, or about 100%, identical to the CDRs of a light chain variable region of the Ofatumumab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 44, SEQ ID NO: 45, SEQ ID NO: 46, respectively), or the CDRs of a light chain variable region of the Rituximab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 55, SEQ ID NO: 57, SEQ ID NO: 59, respectively), or the CDRs of a light chain variable region of the Obinutuzumab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 69, SEQ ID NO: 71, SEQ ID NO: 73, respectively). In certain embodiments, a heavy chain variable region of the anti-CD20 antigen-binding region includes three CDRs that are identical (e.g., 80% - 100% identical) to the CDRs of a heavy chain variable region of the Ofatumumab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43, respectively), and a light chain variable region of the anti-CD20 antigen-binding region includes three CDRs that are identical (e.g., 80% - 100% identical) to the CDRs of a light chain variable region of the Ofatumumab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 44, SEQ ID NO: 45, SEQ ID NO: 46, respectively). In certain embodiments, a heavy chain variable region of the anti-CD20 antigen-binding region includes three CDRs that are identical (e.g., 80% - 100% identical) to the CDRs of a heavy chain variable region of the Rituximab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 48, SEQ ID NO: 50, SEQ ID NO: 52, respectively), and a light chain variable region of the anti-CD20 antigen-binding region includes three CDRs that are identical (e.g., 80% - 100% identical) to the CDRs of a light chain variable region of the Rituximab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 55, SEQ ID NO: 57, SEQ ID NO: 59, respectively). In certain embodiments, a heavy chain variable region of the anti-CD20 antigen-binding region includes three CDRs that are identical (e.g., 80% - 100% identical) to the CDRs of a heavy chain variable region of the Obinutuzumab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 62, SEQ ID NO: 64, SEQ ID NO: 66, respectively), and a light chain variable region of the anti-CD20 antigen-binding region includes three CDRs that are identical (e.g., 80% - 100% identical) to the CDRs of a light chain variable region of the Obinutuzumab antibody (CDR1, CDR2 and CDR3 as set forth in SEQ ID NO: 69, SEQ ID NO: 71, SEQ ID NO: 73, respectively). In certain embodiments, the CAR may comprise an amino acid sequence about 80% to about 100%, about 85% to about 100%, about 90% to about 100%, about 95% to about 100%, at least or about 70%, at least or about 75%, at least or about 80%, at least or about 85%, at least or about 90%, at least or about 95%, at least or about 99%, at least or about 81%, at least or about 82%, at least or about 83%, at least or about 84%, at least or about 85%, at least or about 86%, at least or about 87%, at least or about 88%, at least or about 89%, at least or about 90%, at least or about 91%, at least or about 92%, at least or about 93%, at least or about 94%, at least or about 95%, at least or about 96%, at least or about 97%, at least or about 98%, at least or about 99%, or about 100%, identical to the amino acid sequence set forth in SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 29, or SEQ ID NO: 31. In certain embodiments, the nucleic acid encoding the CAR may comprise a nucleic acid sequence about 80% to about 100%, about 85% to about 100%, about 90% to about 100%, about 95% to about 100%, at least or about 70%, at least or about 75%, at least or about 80%, at least or about 85%, at least or about 90%, at least or about 95%, at least or about 99%, at least or about 81%, at least or about 82%, at least or about 83%, at least or about 84%, at least or about 85%, at least or about 86%, at least or about 87%, at least or about 88%, at least or about 89%, at least or about 90%, at least or about 91%, at least or about 92%, at least or about 93%, at least or about 94%, at least or about 95%, at least or about 96%, at least or about 97%, at least or about 98%, at least or about 99%, or about 100%, identical to the nucleic acid sequence set forth in SEQ ID NO: 2, SEQ ID NO: 4, SEQ ID NO: 6, SEQ ID NO: 30, or SEQ ID NO: 32. In certain embodiments, the CAR may generate an area under the curve (AUC) ranging from about 1.0e+05 copies/µg genomic DNA (copies/gDNA) to about 1.1e+07 copies/gDNA, from about 2.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.1e+07 copies/gDNA, from about 1.0e+05 copies/µg genomic DNA (copies/gDNA) to about 4.0e+06 copies/gDNA, from about 1.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.0e+07 copies/gDNA, from about 0.5e+06 copies/µg genomic DNA (copies/gDNA) to about 2e+07 copies/gDNA, from about 5.0e+05 copies/µg genomic DNA (copies/gDNA) to about 1.3e+07 copies/gDNA, from about 5.0e+05 copies/µg genomic DNA (copies/gDNA) to about 2e+07 copies/gDNA, from about 5.0e+05 copies/µg genomic DNA (copies/gDNA) to about 1.5e+07 copies/gDNA, from about 5.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.0e+07 copies/gDNA, from about 5.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.3e+07 copies/gDNA, from about 7.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.0e+07 copies/gDNA, from about 8.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.0e+07 copies/gDNA, from about 0.5e+06 copies/µg genomic DNA (copies/gDNA) to about 4e+06 copies/gDNA, from about 0.5e+06 copies/µg genomic DNA (copies/gDNA) to about 3.5e+06 copies/gDNA, from about 1e+06 copies/µg genomic DNA (copies/gDNA) to about 3.5e+06 copies/gDNA, from about 1.2e+06 copies/µg genomic DNA (copies/gDNA) to about 3.2e+06 copies/gDNA, from about 0.8e+06 copies/µg genomic DNA (copies/gDNA) to about 3.2e+06 copies/gDNA, from about 1.6e+06 copies/µg genomic DNA (copies/gDNA) to about 3.2e+06 copies/gDNA, from about 1e+06 copies/µg genomic DNA (copies/gDNA) to about 2e+06 copies/gDNA, from about 0.6e+06 copies/µg genomic DNA (copies/gDNA) to about 1.8e+06 copies/gDNA, from about 3e+06 copies/µg genomic DNA (copies/gDNA) to about 3.2e+06 copies/gDNA, from about 0.5e+06 copies/µg genomic DNA (copies/gDNA) to about 1.7e+06 copies/gDNA, from about 2e+06 copies/µg genomic DNA (copies/gDNA) to about 3.2e+06 copies/gDNA, from about 1.5e+06 copies/µg genomic DNA (copies/gDNA) to about 2e+06 copies/gDNA, or from about 1e+06 copies/µg genomic DNA (copies/gDNA) to about 3.2e+06 copies/gDNA, in the blood of the subject in about 28 days after administration of the CAR to the subject. The AUC may be a median AUC. In certain embodiments, the CAR generates a maximum plasma concentration (C_max) ranging from about 1.0e+04 copies/µg genomic DNA (copies/gDNA) to about 1.1e+06 copies/gDNA, from about 1.0e+04 copies/µg genomic DNA (copies/gDNA) to about 3.0e+05 copies/gDNA, from about 2.0e+05 copies/µg genomic DNA (copies/gDNA) to about 1.1e+06 copies/gDNA, from about 5x10⁴ copies/µg genomic DNA (copies/gDNA) to about 1.3x10⁶ copies/gDNA, from about 5x10⁴ copies/µg genomic DNA (copies/gDNA) to about 1.5x10⁶ copies/gDNA, from about 5x10⁵ copies/µg genomic DNA (copies/gDNA) to about 1.3x10⁶ copies/gDNA, from about 7.5x10⁵ copies/µg genomic DNA (copies/gDNA) to about 1x10⁶ copies/gDNA, from about 7x10⁵ copies/µg genomic DNA (copies/gDNA) to about 1x10⁶ copies/gDNA, from about 8x10⁵ copies/µg genomic DNA (copies/gDNA) to about 1x10⁶ copies/gDNA, from about 7.5x10⁵ copies/µg genomic DNA (copies/gDNA) to about 1.5x10⁶ copies/gDNA, from about 7x10⁵ copies/µg genomic DNA (copies/gDNA) to about 1.5x10⁶ copies/gDNA, from about 8x10⁵ copies/µg genomic DNA (copies/gDNA) to about 1.5x10⁶ copies/gDNA, from about 0.8e+05 copies/µg genomic DNA (copies/gDNA) to about 3.5e+05 copies/gDNA, from about 1e+05 copies/µg genomic DNA (copies/gDNA) to about 3.5e+05 copies/gDNA, from about 1e+05 copies/µg genomic DNA (copies/gDNA) to about 1.6e+05 copies/gDNA, from about 1e+05 copies/µg genomic DNA (copies/gDNA) to about 3.3e+05 copies/gDNA, from about 0.8e+05 copies/µg genomic DNA (copies/gDNA) to about 1.5e+05 copies/gDNA, from about 0.8e+05 copies/µg genomic DNA (copies/gDNA) to about 2e+05 copies/gDNA, from about 1e+05 copies/µg genomic DNA (copies/gDNA) to about 2e+05 copies/gDNA, from about 2e+05 copies/µg genomic DNA (copies/gDNA) to about 3e+05 copies/gDNA, from about 2e+05 copies/µg genomic DNA (copies/gDNA) to about 3.5e+05 copies/gDNA, from about 2e+05 copies/µg genomic DNA (copies/gDNA) to about 2.5e+05 copies/gDNA, or from about 1e+05 copies/µg genomic DNA (copies/gDNA) to about 3e+05 copies/gDNA, in the blood of the subject after administration of the CAR to the subject. The C_max may be a median C_max. In certain embodiments, the CAR has a T_max (the time it takes the CAR to reach C_max) ranging from about 10 days to about 25 days, from about 10 days to about 20 days, from about 12 days to about 15 days, from about 12 days to about 25 days, from about 14 days to about 20 days, from about 6 days to about 22 days, from about 3 days to about 20 days, from about 4 days to about 18 days, from about 5 days to about 17 days, from about 6 days to about 16 days, from about 7 days to about 15 days, from about 9 days to about 15 days, from about 10 days to about 15 days, from about 10 days to about 14 days, from about 8 days to about 12 days, from about 6 days to about 14 days, from about 12 days to about 14 days, from about 8 days to about 11 days, from about 8 days to about 15 days, about 5 days, about 6 days, about 7 days, about 8 days, about 9 days, about 10 days, about 11 days, about 12 days, about 13 days, about 14 days, about 15 days, about 16 days, about 17 days, about 18 days, about 19 days, about 20 days, about 21 days, about 22 days, about 23 days, about 24 days, about 25 days, about 26 days, or from about 10 days to about 14 days. The T_max may be a median T_max. In certain embodiments, the CAR has a T_last (the time corresponding to the last quantifiable CAR level) ranging from about 10 days to about 200 days, from about 10 days to about 100 days, from about 10 days to about 90 days, from about 50 days to about 80 days, from about 70 days to about 90 days, from about 30 days to about 90 days, from about 30 days to about 80 days, from about 30 days to about 200 days, from about 50 days to about 150 days, from about 50 days to about 100 days, from about 60 days to about 80 days, from about 60 days to about 150 days, from about 80 days to about 150 days, from about 50 days to about 200 days, from about 50 days to about 60 days, from about 50 days to about 80 days, from about 50 days to about 100 days, from about 60 days to about 100 days, from about 80 days to about 100 days, from about 60 days to about 200 days, from about 80 days to about 200 days, from about 50 days to about 140 days, from about 60 days to about 140 days, or from about 80 days to about 140 days. The T_last may be a median T_last. In view of the differences in affinity and killing mechanisms of the therapeutic antibodies targeting CD20, we constructed a series of chimeric antigen receptors targeting CD20 using the antigen-binding regions of different antibodies, and completed the identification of anti-tumor activity and differential comparison of these chimeric antigen receptor T cells in vitro. The disclosure provides new and effective methods and preparations for clinical application of CAR- T in the treatment of CD20-positive leukemia and lymphoma. It is an object of the present disclosure to provide chimeric antigen receptors targeting CD20, a preparation method and application thereof. The present disclosure relates to the construction of chimeric antigen receptors targeting CD20, a preparation method of chimeric antigen receptor engineered T cells targeting CD20, and activity identification thereof. In a first aspect of the disclosure, it provides a chimeric antigen receptor (CAR) (sequence), whose antigen binding domain (e.g., scFv) comprises an antibody heavy chain variable region as shown in SEQ ID NOs: 7 or 9 or 33 and an antibody light chain variable region as shown in SEQ ID NOs: 11 or 13 or 35. In another embodiment, the antigen binding domain of the chimeric antigen receptor is as follows: V_H-V_L wherein V_H is an antibody heavy chain variable region; V_L is an antibody light chain variable region; and "-" is a linker peptide or a peptide bond. In another embodiment, the amino acid sequence of the linker peptide is as shown in SEQ ID NO: 15. In another embodiment, the amino acid sequence of V_H is as shown in SEQ ID NO: 7, and the amino acid sequence of V_L is as shown in SEQ ID NO: 11. In another embodiment, the amino acid sequence of V_H is as shown in SEQ ID NO: 9, and the amino acid sequence of V_L is as shown in SEQ ID NO: 13. In another embodiment, the amino acid sequence of V_H is as shown in SEQ ID NO: 33, and the amino acid sequence of V_L is shown in SEQ ID NO: 35. In another embodiment, the structure of the chimeric antigen receptor is as follows: L-V_H-V_L-H-TM-CS-CD3ζ wherein, L is an optional leader sequence (i.e., signal peptide); H is a hinge region; TM is a transmembrane domain; CS is a co-stimulatory region or molecule derived from 4-1BB and/or CD28; CD3ζ is a cytoplasmic signaling domain or sequence derived from CD3ζ; V_H, V_L, and "-" are as described above, respectively. In another embodiment, the sequence of L is as shown in SEQ ID NO: 27. In certain embodiments, the signal peptide may comprise an amino acid sequence about 80% to about 100%, about 85% to about 100%, about 90% to about 100%, about 95% to about 100%, at least or about 70%, at least or about 75%, at least or about 80%, at least or about 85%, at least or about 90%, at least or about 95%, at least or about 99%, at least or about 81%, at least or about 82%, at least or about 83%, at least or about 84%, at least or about 85%, at least or about 86%, at least or about 87%, at least or about 88%, at least or about 89%, at least or about 90%, at least or about 91%, at least or about 92%, at least or about 93%, at least or about 94%, at least or about 95%, at least or about 96%, at least or about 97%, at least or about 98%, at least or about 99%, or about 100%, identical to the amino acid sequence set forth in SEQ ID NO: 27. In another embodiment, the sequence of H is as shown in SEQ ID NO: 17 or 19. In certain embodiments, the hinge region may comprise an amino acid sequence about 80% to about 100%, about 85% to about 100%, about 90% to about 100%, about 95% to about 100%, at least or about 70%, at least or about 75%, at least or about 80%, at least or about 85%, at least or about 90%, at least or about 95%, at least or about 99%, at least or about 81%, at least or about 82%, at least or about 83%, at least or about 84%, at least or about 85%, at least or about 86%, at least or about 87%, at least or about 88%, at least or about 89%, at least or about 90%, at least or about 91%, at least or about 92%, at least or about 93%, at least or about 94%, at least or about 95%, at least or about 96%, at least or about 97%, at least or about 98%, at least or about 99%, or about 100%, identical to the amino acid sequence set forth in SEQ ID NO: 17 or SEQ ID NO: 19. In another embodiment, the sequence of TM comprises a transmembrane region derived from CD8a or CD28. For example, the sequence of TM is as shown in SEQ ID NO: 21 or 37. In certain embodiments, the transmembrane domain may comprise an amino acid sequence about 80% to about 100%, about 85% to about 100%, about 90% to about 100%, about 95% to about 100%, at least or about 70%, at least or about 75%, at least or about 80%, at least or about 85%, at least or about 90%, at least or about 95%, at least or about 99%, at least or about 81%, at least or about 82%, at least or about 83%, at least or about 84%, at least or about 85%, at least or about 86%, at least or about 87%, at least or about 88%, at least or about 89%, at least or about 90%, at least or about 91%, at least or about 92%, at least or about 93%, at least or about 94%, at least or about 95%, at least or about 96%, at least or about 97%, at least or about 98%, at least or about 99%, or about 100%, identical to the amino acid sequence set forth in SEQ ID NO: 21 or SEQ ID NO: 37. In another embodiment, the CS structure is: CD28-4-1BB, wherein CD28 is a co- stimulatory molecule derived from CD28; and 4-1BB is a co-stimulatory molecule derived from 4-1BB. In another embodiment, the sequence of the co-stimulatory molecule derived from 4-1BB is as shown in SEQ ID NO: 23. In another embodiment, the sequence of the co-stimulatory molecule derived from CD28 is as shown in SEQ ID NO: 39. In certain embodiments, the co-stimulatory region may comprise an amino acid sequence about 80% to about 100%, about 85% to about 100%, about 90% to about 100%, about 95% to about 100%, at least or about 70%, at least or about 75%, at least or about 80%, at least or about 85%, at least or about 90%, at least or about 95%, at least or about 99%, at least or about 81%, at least or about 82%, at least or about 83%, at least or about 84%, at least or about 85%, at least or about 86%, at least or about 87%, at least or about 88%, at least or about 89%, at least or about 90%, at least or about 91%, at least or about 92%, at least or about 93%, at least or about 94%, at least or about 95%, at least or about 96%, at least or about 97%, at least or about 98%, at least or about 99%, or about 100%, identical to the amino acid sequence set forth in SEQ ID NO: 23 or SEQ ID NO: 39. In another embodiment, the sequence of CD3ζ is as shown in SEQ ID NO: 25. In certain embodiments, the cytoplasmic signaling domain may comprise an amino acid sequence about 80% to about 100%, about 85% to about 100%, about 90% to about 100%, about 95% to about 100%, at least or about 70%, at least or about 75%, at least or about 80%, at least or about 85%, at least or about 90%, at least or about 95%, at least or about 99%, at least or about 81%, at least or about 82%, at least or about 83%, at least or about 84%, at least or about 85%, at least or about 86%, at least or about 87%, at least or about 88%, at least or about 89%, at least or about 90%, at least or about 91%, at least or about 92%, at least or about 93%, at least or about 94%, at least or about 95%, at least or about 96%, at least or about 97%, at least or about 98%, at least or about 99%, or about 100%, identical to the amino acid sequence set forth in SEQ ID NO: 25. In another embodiment, the sequence of the chimeric antigen receptor is as shown in SEQ ID NOs: 1, 3, 5, 29, or 31. In a second aspect of the invention, a nucleic acid molecule is provided, encoding the chimeric antigen receptor (CAR) of the first aspect of the disclosure. In another embodiment, the nucleic acid molecule comprises a nucleic acid sequence encoding the hinge region selected from the group consisting of: (a) a polynucleotide encoding a polypeptide as shown in SEQ ID NO: 17 or 19; (b) a polynucleotide having a sequence as shown in SEQ ID NO: 18 or 20; (c) a polynucleotide having a nucleotide sequence with ≥90% (preferably ≥95%) homologous to the sequence of SEQ ID NO: 18 or 20, and encoding the amino acid sequence of SEQ ID NO: 17 or 19; (d) a polynucleotide complementary to the polynucleotide of any of (a) to (c). In another embodiment, the nucleic acid molecule comprises a nucleic acid sequence encoding the CD8a transmembrane region selected from the group consisting of: (a) a polynucleotide encoding a polypeptide as shown in SEQ ID NO: 21; (b) a polynucleotide having a sequence as shown in SEQ ID NO: 22; (c) a polynucleotide having a nucleotide sequence with ≥90% (preferably ≥95%) homologous to the sequence of SEQ ID NO: 22 and encoding the amino acid sequence of SEQ ID NO: 21; (d) a polynucleotide complementary to the polynucleotide of any of (a) to (c). In another embodiment, the nucleic acid molecule comprises a nucleic acid sequence encoding the 4-1BB (CD137) intracellular signal domain selected from the group consisting of: (a) a polynucleotide encoding a polypeptide as shown in SEQ ID NO: 23; (b) a polynucleotide having a sequence as shown in SEQ ID NO: 24; (c) a polynucleotide having a nucleotide sequence with ≥90% (preferably ≥95%) homologous to the sequence of SEQ ID NO: 24 and encoding the amino acid sequence of SEQ ID NO: 23; (d) a polynucleotide complementary to the polynucleotide of any of (a) to (c). In another embodiment, the nucleic acid molecule comprises a nucleic acid sequence encoding the CD28 intracellular signal domain selected from the group consisting of: (a) a polynucleotide encoding a polypeptide as shown in SEQ ID NO: 39; (b) a polynucleotide having a sequence as shown in SEQ ID NO: 40; (c) a polynucleotide having a nucleotide sequence with ≥90% (preferably ≥95%) homologous to the sequence of SEQ ID NO: 40 and encoding the amino acid sequence of SEQ ID NO: 39; (d) a polynucleotide complementary to the polynucleotide of any of (a) to (c). In another embodiment, the nucleic acid molecule comprises a nucleic acid sequence encoding the CD3ζ intracellular signal domain selected from the group consisting of: (a) a polynucleotide encoding a polypeptide as shown in SEQ ID NO: 25; (b) a polynucleotide having a sequence as shown in SEQ ID NO: 26; (c) a polynucleotide having a nucleotide sequence with ≥90% (preferably ≥95%) homologous to the sequence of SEQ ID NO: 26 and encoding the amino acid sequence of SEQ ID NO: 25; (d) a polynucleotide complementary to the polynucleotide of any of (a) to (c). In another embodiment, the nucleic acid molecule comprises a nucleic acid sequence selected from the group consisting of: (a) a polynucleotide encoding a polypeptide as shown in SEQ ID NOs: 1, 3, 5, 29 or 31; (b) a polynucleotide having the sequence as shown in SEQ ID NOs: 2, 4, 6, 30 or 32; (c) a polynucleotide having a nucleotide sequence with ≥95% (preferably ≥98%) homologous to the sequence of SEQ ID NOs: 2, 4, 6, 30 or 32, and encoding the amino acid sequence of SEQ ID NOs: 1, 3, 5, 29 or 31; (d) a polynucleotide complementary to the polynucleotide of any of (a) to (c). In another embodiment, the nucleic acid molecule is isolated. In another embodiment, the nucleic acid molecule further comprises a polynucleotide encoding the leader sequence (directing sequence, signal peptide), and the amino acid sequence of the leader sequence is as shown in SEQ ID NO: 27; the polynucleotide encoding the leader sequence (signal peptide) may be as shown in SEQ ID NO: 28. In another embodiment, the sequence of the nucleic acid molecule is as shown in SEQ ID NOs: 2, 4, 6, 30 or 32. In a third aspect of the disclosure, it provides a vector, comprising the nucleic acid molecule of the second aspect of the invention. In another embodiment, the vector is a lentiviral vector. In a fourth aspect of the disclosure, it provides a host cell comprising the vector of the third aspect of the disclosure or having the exogenous nucleic acid molecule of the second aspect of the disclosure integrated into its genome. In another embodiment, the cell is an isolated cell, and/or the cell is a genetically engineered cell. In another embodiment, the cell is a mammalian cell. In another embodiment, the cell is a T cell. In a fifth aspect of the disclosure, it provides a pharmaceutical composition comprising a pharmaceutically acceptable carrier and the chimeric antigen receptor of the first aspect of the disclosure, the nucleic acid molecule of the second aspect of the disclosure, the vector of the third aspect of the disclosure, or the cell of the fourth aspect of the disclosure. In a sixth aspect of the disclosure, it provides the use of the chimeric antigen receptor of the first aspect of the disclosure, the nucleic acid molecule of the second aspect of the disclosure, the vector of the third aspect of the disclosure, or the cell of the fourth aspect of the disclosure for the preparation of a medicine or a formulation for treating tumor or autoimmune disease. In another embodiment, the autoimmune disease is an autoimmune disease caused by overexpression of B cells (such as lupus erythematosus). In another embodiment, the tumor comprises CD20 positive tumor. In a seventh aspect of the disclosure, it provides a method for treating a disease comprising administering an appropriate amount of the chimeric antigen receptor of the first aspect of the disclosure, the nucleic acid molecule of the second aspect of the disclosure, the vector of the third aspect of the disclosure, the cell of the fourth aspect of the disclosure, or the pharmaceutical composition of the fifth aspect of the disclosure, to a subject in need of treatment. In another embodiment, the disease is tumor. In an eighth aspect of the disclosure, it provides a method for preparing a CAR-T cell (CAR-modified T cell) expressing the chimeric antigen receptor of the first aspect of the disclosure. The method may comprise the steps of: transducing the nucleic acid molecule of the second aspect of the disclosure or the vector of the third aspect of the disclosure into a T cell, thereby obtaining the CAR-T cell. It is to be understood that the various technical features of the present disclosure mentioned above and the various technical features specifically described hereinafter (as in the Examples) may be combined with each other within the scope of the present disclosure to constitute a new or preferred technical solution, which will not be repeated one by one herein.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the structure of the chimeric antigen receptor targeting CD20. Each element of the designed CAR structure is shown in the figure, and the listed elements include: a leader sequence, an antigen recognition sequence (Ofatumumaband, Obinutuzumab, Rituximab), a hinge region, a transmembrane region, a co-stimulatory region, and a CD3ζ signaling region. CAR-T20.14, CAR-T20.13 and CAR-T20.16 are CAR structures constructed based on the antibody variable region sequences of Ofatumumab, Obinutuzumab and Rituxmab, respectively. CAR-T20.19 and CAR-20.20 are the mutant form of CAR-T20.14, having L235E-N297Q mutation in IgG4 Hinge-CH2-CH3 linker region. CAR-T20.20 is a third-generation chimeric antigen receptor structure with coding sequences of both CD28 and 4-1BB co-stimulatory signaling molecule. Figures 2A-2B show detection of transfection efficiency of engineered T cell with chimeric antigen receptors targeting CD20. The expression level of the CAR gene-encoded protein on the surface of the T cell membrane in CAR-T20s cells cultured on day 7 (Figure 2A) and day 11 (Figure 2B) was identified by the Protein L method. Figures 3A-3B.1*10⁵ of NT, CART-20.13, CART-20.14 and CAR-T20.16 cells (cultured on day 6) were co-cultured respectively with CD20-positive RAJI and RAMOS tumor cell lines, and CD20-negative MOLT-4 tumor cell line in 200 μl GT-551 medium for 18h in a ratio of 1:1. Then the expression level of CD137 on the surface of T cell membrane (Figure 3A) and the secretion level of IFNγ in the co-culture supernatant (Figure 3B) were detected. Figure 4 shows detection of apoptosis levels of tumor cells induced by CART-20.1*10⁴ of CFSE-labeled CD20-negative (MOLT-4) or CD20-positive (RAJI, RAMOS) tumor cell lines were co-cultured respectively with NT, CART-20.13, CART-20.14 and CAR-T20.16 cells (cultured on day 11) in 200 μl GT-551 medium for 4h according to the ratio as shown in figure. Then the cell pellet was collected by centrifugation. The cells were washed twice with PBS and stained for 30 min with Annexin V-APC dye in a ratio of 1:50 in 100 μl of dyeing solution. After washing with PBS for 1 time, the proportion of Annexin V positive cells in CFSE positive cells was analyzed on a flow cytometry. The results in figure show the statistical analysis of Annexin V positive cells in the corresponding co-culture samples. Figures 5A-5C show identification of the activation ability in vitro of the third-generation chimeric antigen receptor and the chimeric antigen receptor with mutation in hinge region (which are constructed based on the sequence of Ofatumumaband antibody). The expression level of the CAR gene-encoded protein (Figure 5A) on the surface of the T cell membrane in CAR-T20.14, CAR-T20.19 and CAR-T20.20 cells cultured on day 7 was identified by the Protein L method.1*10⁵ of NT, CART-20.14, CART-20.19 and CAR-T20.20 cells (cultured on day 7) were cultured respectively with K562, K562 stable transfected cells of CD19 single positive, CD20 single positive, CD19 and CD20 double positive, and RAJI target cell in 200 μl GT-551 medium for 18h in a ratio of 1:1. Then the expression level of CD137 on the surface of T cell membrane (Figure 5B) and the secretion level of IFNγ in the culture supernatant (Figure 5C) were detected, respectively. Figure 6 shows the detection results of the ability of CAR-T20 cells to scavenge CD20- positive cells in vivo. The results indicate that CAR-T20.19 can effectively inhibit the in vivo expansion of CD20-positive tumor cells. Figures 7A-7D show the screening of scFv for anti-CD20-CARs. Figure 7A shows the structures of CAR-T20.1, CAR-T20.9 to CAR-T20.16. Figure 7B shows the secretion levels of IFNγ. Figure 7C shows the structures of CAR-T20.9, CAR-T20.12, CAR-T20.14, CAR-T20.17 to CAR-T20.19 (C-CAR066). Figure 7B shows the secretion levels of IFNγ. Figures 8A-8D show the lead selection for anti-CD20-CARs. Figure 8A shows the structures of CAR-T20.17, CAR-T20.18 and CAR-T20.19 (C-CAR066). Figure 8B shows the secretion levels of IFNγ. CAR-T20.19: CART20-OF(2nd). CAR-T20.17: CART20-LEU (3rd), which is the third-generation CAR with Leu-16 scFv. CAR-T20.18: CART20-LEU (2nd), which is the second-generation CAR with Leu-16 scFv. Figure 8C shows the cytotoxicity of CAR- T20.17, CAR-T20.18 and CAR-T20.19 (C-CAR066). Figure 8D shows in vivo anti-tumor efficacy of CAR-T20.17, CAR-T20.18 and CAR-T20.19 (C-CAR066). Figure 9A shows the structures of CAR-T20.19 (C-CAR066) and CAR-T20.29. Figure 9B shows that CAR-T20.19 (C-CAR066) has the optimized V_H-V_L scFv structure. Figures 10A-10D show that CAR-T20.19 (C-CAR066) had superior in vivo anti-tumor activity. C-CAR011 is anti-CD1941BB CAR with FMC63. Figure 11 shows an example of the CAR (C-CAR066) manufacture process. The process includes the usage of serum free media, and a functionally closed, highly automated system. Stars indicate improved processes. Figure 12 shows CAR066 Phase I clinical study design and flow chart. A Phase I, first in human, open-label study targeting/r B-NHL patients after failing CD19 CAR-T therapy conducted at two sites. Enrollment key eligibility criteria include 18-75 years old; measurable lesion, CD19 CAR-T failure, no active infection, adequate organ function and no CNS lesion. Objectives include the following. Primary objectives include incidence and severity of TEAEs (CTCAE V5.0 and ASTCT). Secondary objectives include ORR, DOR, PFS, OS (Lugano 2014). Exploratory objectives include CAR-T expansion and persistence. Figure 13 shows the CRS safety profile of C-CAR066. Figure 14A shows the C-CAR066 clinical response, including SD, PR, CR, and PD. SD: stable disease; PR: partial response; CR: complete response; PD: progressive disease. Figure 14B shows the Kaplan Meyer estimation of progression-free survival (PFS). Figure 14C shows the tumor burden (% change) in the seven patients. Figure 15A shows a case study where CR was achieved at 4 weeks with bulky disease. Figure 15B shows the PET-CT images of the cancer lesions for one patient, patient No.2. Figures 16A-16F show C-CAR066 PK/PD profiles. Figure 16A shows the changes of C- CAR066 CAR copies in the peripheral blood of the patients after CAR administration over time. Figure 16B shows the changes of CD20+ B cell levels in the peripheral blood of the patients after CAR administration over time. Figure 16C shows C_max levels in the blood of the patients after CAR administration. Figure 16D shows AUC levels in the blood of the patients after CAR administration. Figure 16E shows T_max levels in the blood of the patients after CAR administration. Figure 16F shows T_last levels in the blood of the patients after CAR administration. Low dose: 2.0 x 10⁶ CAR-T cells/kg; mid dose: 3.0 x 10⁶ CAR-T cells/kg; high dose: 4.8 x 10⁶ CAR-T cells/kg. Figure 17 shows CD19/CD20 expression and PK/PD in C-CAR066 relapsed patients, including CAR-T expansion and B cell depletion in peripheral blood.

DETAILED DESCRIPTION The present disclosure provides for chimeric antigen receptors (CARs) targeting CD20. In certain embodiments, the CARs are based on three antibodies: Ofatumumab, Rituximab and Obinutuzumab. The present disclosure also provides for the in vitro activities and tumor cell killing efficacy of these chimeric antigen receptors. Studies have shown that the chimeric antigen receptors of the present disclosure target CD20-positive cells and can be used to treat a hematologic cancer including a B-cell malignancy such as acute lymphocytic leukemia (ALL), chronic lymphocytic leukemia (CLL), B-cell acute lymphoblastic leukemia (B-ALL), B-cell leukemia, or B cell lymphoma. The present CARs may be used to treat Hodgkin's lymphoma, non-Hodgkin's lymphoma, leukemia, and/or multiple myeloma (MM). Chimeric antigen receptors targeting CD20 and the preparation and application thereof are provided. The extracellular antigen binding domain of the chimeric antigen receptor includes the antibody heavy chain variable region and the antibody light chain variable region. The experimental results show that the chimeric antigen receptor provided by the present disclosure shows significantly high killing ability against tumor cells. In view of the differences in affinity, killing mechanism of therapeutic antibodies targeting CD20, as well as the significant effects of different transmembrane domains and intracellular domains on the activity of chimeric antigen receptor, a series of chimeric antigen receptors targeting CD20 were constructed in the present disclosure by combining various transmembrane and intracellular components with the amino acid sequences of the variable regions in various anti-CD20 antibodies. The expression of such chimeric antigen receptors in T cells (e.g., primary T cells) was completed. The detection method of receptor expression intensity was established. The ability of the CAR-T cells to recognize CD20 antigen in vitro and in vivo, as well as the difference in the activity of scavenging malignant tumors carrying CD20 antigen in vitro and in vivo were identified, providing a new effective method and preparation for the clinical application of CAR T in treating CD20 positive leukemia and lymphoma. Chimeric antigen receptors The disclosure provides a chimeric antigen receptor (CAR) comprising an extracellular domain, a transmembrane domain, and an intracellular domain. The extracellular domain comprises a target-specific binding element (also known as an antigen binding region or domain). The intracellular domain includes a co-stimulatory (signaling) region and a ζ chain moiety. The co-stimulatory signaling region refers to a part of the intracellular domain that includes a co-stimulatory molecule. The co-stimulatory molecule is a cell surface molecule for efficient response of lymphocytes to antigens, rather than an antigen receptor or its ligand. A linker can be incorporated between the extracellular domain and the transmembrane domain of the CAR, or between the cytoplasmic domain and the transmembrane domain of the CAR. As used herein, the term "linker" generally refers to any oligopeptide or polypeptide that plays a role of linking the two components of the CAR. For example, a linker can link the transmembrane domain to the extracellular domain or the cytoplasmic domain in a polypeptide chain. The linker may comprise 0-300 amino acids, 2-100 amino acids, or 3-50 amino acids. In certain embodiment, the extracellular domain of the CAR provided by the present disclosure comprises an antigen binding domain targeting CD20. When the CAR of the present disclosure is expressed in T cells, antigen recognition can be performed based on antigen binding specificity. When it binds to its cognate antigen, it affects a tumor cell so that the tumor cell fails to grow, is prompted to die, or otherwise is affected so that the tumor burden in a patient is diminished or eliminated. The antigen binding domain may be fused with an intracellular domain from one or more of a co-stimulatory molecule and a ζ chain. In one embodiment, the antigen binding domain is fused with an intracellular domain of a combination of a 4-1BB signaling domain and/or a CD28 signaling domain, and a CD3ζ signaling domain. In one embodiment, the CAR targeting CD20 comprises the specific signaling domain (e.g., the transmembrane region of CD8, the intracellular signal domains of CD137 and CD3ζ are in series). The signaling domain of the disclosure significantly increases anti-tumor activity and in vivo persistence of CAR-T cells compared to an otherwise identical CAR targeting CD20. In one embodiment, the amino acid sequence of the chimeric antigen receptor (CAR) provided by the present disclosure is as follows. CAR-T20.13 (SEQ ID NO:29) The DNA sequence encoding CAR-T20.13 (SEQ ID NO: 30) may be as follows: The amino acid sequence of CAR-T20.14 (SEQ ID NO:1): The DNA sequence encoding CAR-T20.14 (SEQ ID NO: 2) is as follows: The amino acid sequence of CAR-T20.16 (SEQ ID NO:3) The DNA sequence encoding CAR-T20.16 (SEQ ID NO: 4) is as follows: In another embodiment, the amino acid sequence of the chimeric antigen receptor (CAR) provided by the disclosure is as follows. The amino acid sequence of CAR-T20.19 (SEQ ID NO:5) The DNA sequence encoding CAR-T20.19 (SEQ ID NO: 6) is as follows: In one embodiment, the amino acid sequence of the chimeric antigen receptor (CAR) provided by the invention is as follows. The amino acid sequence of CAR-T20.20 (SEQ ID NO:31) The coding DNA sequence of CAR-T20.20 (SEQ ID NO: 32) is as follows: Antigen binding region (domain) In one embodiment, the CAR of the disclosure comprises a target-specific binding element referred to as antigen binding region or domain. The antigen binding domain of the present CAR is a specific binding element targeting CD20. In one embodiment, the antigen binding domain comprises a heavy chain variable region and a light chain variable region of an anti-CD20 antibody. In another embodiment, the amino acid sequence of the heavy chain variable region of the Ofatumumab antibody is as follows: The DNA sequence encoding the heavy chain variable region of the Ofatumumab antibody is as follows: The amino acid sequence of the heavy chain variable region of the Rituximab antibody is as follows: The DNA sequence encoding the heavy chain variable region of the Rituximab antibody is as follows: Further, the amino acid sequence of the heavy chain variable region of the Obinutuzumab antibody used in the present disclosure is as follows: The DNA sequence encoding the heavy chain variable region of the Obinutuzumab antibody is as follows: In another embodiment, the amino acid sequence of the light chain variable region of the Ofatumumaband antibody is as follows: The DNA sequence of Ofatumumaband antibody is as follows: The anti-CD20 CAR comprises an anti-CD20 antigen-binding region which comprises a light chain variable region (V_L) and a heavy chain variable region (V_H). V_L comprises three complementarity determining regions (CDRs), LCDR1, LCDR2 and LCDR3, and V_H comprises three CDRs, HCDR1, HCDR2 and HCDR3. The CDRs of Ofatumumab are as follows. V_H comprises three CDRs: CDR-H1 (HCDR1), CDR-H2 (HCDR2) and CDR-H3 (HCDR3); V_L comprises three CDRs: CDR-L1 (LCDR1), CDR- L2 (LCDR2) and CDR-L3 (LCDR3). CDR-H1: NDYAMH (SEQ ID NO: 41) CDR-H2: TISWNSGSIGYADSVKG (SEQ ID NO: 42) CDR-H3: DIQYGNYYYGMDV (SEQ ID NO: 43) CDR-L1: RASQSVSSYLA (SEQ ID NO: 44) CDR-L2: DASNRAT (SEQ ID NO: 45) CDR-L3: QQRSNWPIT (SEQ ID NO: 46) The amino acid sequence of the light chain variable region of the Rituximab antibody is as follows: The DNA sequences encoding the light chain (VL) of single-chain variable region derived from the Rituximab antibody is: The CDRs of Rituximab are as follows. V_H comprises three CDRs: CDR-H1 (HCDR1), CDR-H2 (HCDR2) and CDR-H3 (HCDR3); V_L comprises three CDRs: CDR-L1 (LCDR1), CDR- L2 (LCDR2) and CDR-L3 (LCDR3). Rituximab Heavy Chain (SEQ ID NO: 9) Rituximab Light Chain (SEQ ID NO:13)

Further, the amino acid sequence of the light chain variable region of the Obinutuzumab antibody used in the present disclosure is as follows: The DNA sequence encoding the light chain variable region of the Obinutuzumab antibody is as follows: The CDRs of Obinutuzumab are as follows. V_H comprises three CDRs: CDR-H1 (HCDR1), CDR-H2 (HCDR2) and CDR-H3 (HCDR3); V_L comprises three CDRs: CDR-L1 (LCDR1), CDR-L2 (LCDR2) and CDR-L3 (LCDR3). Obinutuzumab Heavy Chain (SEQ ID NO:33)

Obinutuzumab Light Chain (SEQ ID NO:35) In one embodiment, the amino acid sequence of the linker between the heavy chain variable region and the light chain variable region is as follows: Its coding DNA sequence is as follows: Hinge region and transmembrane domain (region) As for the hinge region and the transmembrane region (transmembrane domain), the CAR can be designed to comprise a transmembrane domain fused to the extracellular domain of the CAR. In one embodiment, a transmembrane domain that is naturally associated with one of the domains in the CAR is used. In some embodiments, transmembrane domains may be selected or modified by amino acid substitutions to avoid binding such domains to the transmembrane domain of the same or different surface membrane proteins, thereby minimizing the interaction with other members of the receptor complexes. In one embodiment, the hinge region comprises the following amino acid sequence (IgG4 Hinge-CH2-CH3 hinge region): Its coding DNA sequence is as follows: In one embodiment, the hinge region comprises the following amino acid sequence (IgG4 Hinge-CH2-CH3 (L235E, N297Q)): Its coding DNA sequence is as follows: In a preferred embodiment of the invention, the amino acid sequence of the transmembrane region derived from CD8 (CD8TM) is as follows: The coding DNA sequence thereof is as follows: In a preferred embodiment of the invention, the amino acid sequence of the transmembrane region derived from CD28 (CD28TM) is as follows: The DNA sequence encoding the transmembrane region derived from CD28 (CD28TM) is as follows: Intracellular domain The intracellular domain in the CAR may comprise the signaling domain of 4-1BB and the signaling domain of CD3ζ. In one embodiment, the intracellular signaling domain of 4-1BB comprises the following amino acid sequence: The coding DNA sequence thereof is as follows: In one embodiment, the intracellular signaling domain derived from CD28 comprises the following amino acid sequence: The coding DNA sequence thereof is as follows: In one embodiment, the intracellular signaling domain of CD3ζ comprises the following amino acid sequence: The coding DNA sequence thereof is as follows: Vector The present disclosure also provides a nucleic acid, a vector, or a DNA construct encoding the present CAR. The nucleic acid sequences coding for the desired molecules can be obtained using recombinant methods known in the art, such as, for example by screening libraries from cells expressing the gene, by deriving the gene from a vector known to include the same, or by isolating directly from cells and tissues containing the same, using standard techniques. Alternatively, the gene of interest can be produced synthetically. The present disclosure also provides vectors in which the DNA construct of the present disclosure is inserted. Vectors derived from retroviruses such as the lentivirus are suitable tools to achieve long-term gene transfer since they allow long-term, stable integration of a transgene and its propagation in daughter cells. Lentiviral vectors have the advantage over vectors derived from onco-retroviruses such as murine leukemia viruses in that they can transduce non- proliferating cells, such as hepatocytes. They also have the advantage of low immunogenicity. In certain embodiments, the expression of natural or synthetic nucleic acids encoding CARs is typically achieved by operably linking a nucleic acid encoding the CAR polypeptide or portions thereof to a promoter, and incorporating the construct into an expression vector. The vectors can be suitable for replication and integration in eukaryotes. Typical cloning vectors contain transcription and translation terminators, initiation sequences, and promoters useful for regulation of the expression of the desired nucleic acid sequence. The expression constructs of the present disclosure may also be used for nucleic acid immune and gene therapy, using standard gene delivery protocols. Methods for gene delivery are known in the art. See, e.g., U.S, Pat. Nos.5,399,346, 5,580,859, 5,589,466, incorporated by reference herein in their entireties. In another embodiment, the present disclosure provides a gene therapy vector. The nucleic acid can be cloned into any suitable types of vectors. For example, the nucleic acid can be cloned into a vector including, but not limited to, a plasmid, a phagemid, a phage derivative, an animal virus, and a cosmid. Vectors of particular interest include expression vectors, replication vectors, probe generation vectors, and sequencing vectors, Further, the expression vector may be provided to a cell in the form of a viral vector. Viral vector technology is well known in the art and is described, for example, in Sambrook et al, (2001, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York), and in other virology and molecular biology manuals. Viruses, which are useful as vectors include, but are not limited to, retroviruses, adenoviruses, adeno-associated viruses, herpes viruses, and lentiviruses. In general, a suitable vector contains an origin of replication functional in at least one organism, a promoter sequence, convenient restriction endonuclease sites, and one or more selectable markers, (e.g., WO 01/96584; WO 01/29058; and U.S, Pat. No. 6,326, 193). A number of virus-based systems have been developed for gene transfer into mammalian cells. For example, retroviruses provide a convenient platform for gene delivery systems. A selected gene can be inserted into a vector and packaged in retroviral particles using techniques known in the art. The recombinant virus can then be isolated and delivered to cells of the subject either in vivo or ex vivo. A number of retroviral systems are known in the art. In some embodiments, adenovirus vectors are used. A number of adenovirus vectors are known in the art. In one embodiment, lentivirus vectors are used. Additional promoter elements, e.g., enhancers, regulate the frequency of transcriptional initiation. Typically, these are located in the region 30-110 bp upstream of the start site, although a number of promoters have recently been shown to contain functional elements downstream of the start site as well. The spacing between promoter elements frequently is flexible, so that promoter function is preserved when elements are inverted or moved relative to one another. In the thymidine kinase (tk) promoter, the spacing between promoter elements can be increased to 50 bp apart before activity begins to decline. Depending on the promoter, it appears that individual elements can function either cooperatively or independently to activate transcription. One example of a suitable promoter is the immediate early cytomegalovirus (CMV) promoter sequence. This promoter sequence is a strong constitutive promoter sequence capable of driving high levels of expression of any polynucleotide sequence operatively linked thereto. Another example of a suitable promoter is Elongation Growth Factor-1α (EF-1α). However, other constitutive promoter sequences may also be used, including, but not limited to, the simian virus 40 (SV40) early promoter, mouse mammary tumor virus (MMTV), human immunodeficiency virus (HIV) long terminal repeat (LTR) promoter, MoMuLV promoter, an avian leukemia virus promoter, an Epstein-Barr virus immediate early promoter, a Rous sarcoma virus promoter, as well as human gene promoters such as, but not limited to, the actin promoter, the myosin promoter, the hemoglobin promoter, and the creatine kinase promoter. Further, the disclosure should not be limited to the use of constitutive promoters, inducible promoters are also contemplated as part of the disclosure. The use of an inducible promoter provides a molecular switch capable of turning on expression of the polynucleotide sequence which it is operatively linked when such expression is desired, or turning off the expression when expression is not desired. Examples of inducible promoters include, but are not limited to, a metallothionein promoter, a glucocorticoid promoter, a progesterone promoter, and a tetracycline promoter. In order to assess the expression of a CAR polypeptide or portions thereof, the expression vector to be introduced into a cell can also contain either a selectable marker gene or a reporter gene or both to facilitate identification and selection of expressing cells from the population of cells sought to be transfected or infected through viral vectors. In other aspects, the selectable marker may be carried on a separate piece of DNA and used in a co-transfection procedure. Both selectable markers and reporter genes may be flanked with appropriate regulatory sequences to enable expression in the host cells. Useful selectable markers include, for example, antibiotic- resistance genes, such as neo and the like. Reporter genes are used for identifying potentially transfected cells and for evaluating the functionality of regulatory sequences. In general, a reporter gene is a gene that is not present in or expressed by the recipient organism or tissue and that encodes a polypeptide whose expression is manifested by some easily detectable property, e.g., enzymatic activity. Expression of the reporter gene is assayed at a suitable time after the DNA has been introduced into the recipient cells. Suitable reporter genes may include genes encoding luciferase, beta- galactosidase, chloramphenicol acetyl transferase, secreted alkaline phosphatase, or the green fluorescent protein gene (e.g., Ui-Tei et al., 2000 FEBS Letters 479: 79-82). Suitable expression systems are well known and may be prepared using known techniques or obtained commercially. In general, the construct with the minimal 5’ flanking region showing the highest level of expression of reporter gene is identified as the promoter. Such promoter regions may be linked to a reporter gene and used to evaluate agents for the ability to modulate promoter-driven transcription. Methods of introducing and expressing genes into a cell are known in the art. In the context of an expression vector, the vector can be readily introduced into a host cell, e.g., mammalian, bacterial, yeast, or insect cell by any method in the art. For example, the expression vector can be transferred into a host cell by physical, chemical, or biological means. Physical methods for introducing a polynucleotide into a host cell include calcium phosphate precipitation, lipofection, particle bombardment, microinjection, electroporation, and the like. Methods for producing cells comprising vectors and/or exogenous nucleic acids are well-known in the art. See, for example, Sambrook et al. (2001, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory, New York). One method for the introduction of a polynucleotide into a host cell is calcium phosphate transfection. Biological methods for introducing a polynucleotide of interest into a host cell include the use of DNA and RNA vectors. Viral vectors, and especially retroviral vectors, have become the most widely used method for inserting genes into mammalian, e.g., human cells. Other viral vectors can be derived from lentivirus, poxviruses, herpes simplex virus I, adenoviruses and adeno-associated viruses, and the like. See, for example, U.S. Pat, Nos.5,350,674 and 5,585,362. Chemical means for introducing a polynucleotide into a host cell include colloidal dispersion systems, such as macromolecule complexes, nanocapsules, microspheres, beads, and lipid-based systems including oil-in-water emulsions, micelles, mixed micelles, and liposomes. An exemplary colloidal system for use as a delivery vehicle in vitro and in vivo is a liposome (e.g., an artificial membrane vesicle). In the case where a non-viral delivery system is utilized, an exemplary delivery vehicle is a liposome. The use of lipid formulations is contemplated for the introduction of the nucleic acids into a host cell (in vitro, ex vivo or in vivo). In another aspect, the nucleic acid may be associated with a lipid. The nucleic acid associated with a lipid may be encapsulated in the aqueous interior of a liposome, interspersed within the lipid bilayer of a liposome, attached to a liposome via a linking molecule that is associated with both the liposome and the oligonucleotide, entrapped in a liposome, complexed with a liposome, dispersed in a solution containing a lipid, mixed with a lipid, combined with a lipid, contained as a suspension in a lipid, contained or complexed with a micelle, or otherwise associated with a lipid. Lipid, lipid/DNA or lipid/expression vector associated compositions are not limited to any particular structure in solution. For example, they may be present in a bilayer structure, as micelles, or with a "collapsed" structure. They may also simply be interspersed in a solution, possibly forming aggregates that are not uniform in size or shape. Lipids are fatty substances which may be naturally occurring or synthetic lipids. For example, lipids include the fatty droplets that naturally occur in the cytoplasm as well as the class of compounds which contain long-chain aliphatic hydrocarbons and their derivatives, such as fatty acids, alcohols, amines, amino alcohols, and aldehydes. In the case where a non-viral delivery system is utilized, genome editing technique may be exemplarily employed, for example CRISPR-Cas9, ZFN or TALEN. In one embodiment, the vector is a lentiviral vector. In certain embodiments, the DNA construct further comprises a signal peptide coding sequence. For example, the signal peptide sequence is ligated upstream of the nucleic acid sequence of antigen binding domain. In one embodiment, the signal peptide is a human CD8a signal peptide. In one embodiment, the amino acid sequence of the signal peptide is as follows. The amino acid sequence of CD8 leader sequence is: The DNA sequence encoding CD8 leader sequence is: As used herein, the terms "CAR-T cell", "CAR-T", and "CART", may be used interchangeably. Therapeutic Application The present disclosure encompasses a cell (e.g., T cell) transduced with a lentiviral vector (LV) encoding the present CAR. The transduced T cell can elicit a CAR-mediated T-cell response. Thus, the present disclosure also provides a method for stimulating a T cell-mediated immune response to a target cell population or tissue in a mammal comprising the step of administering to the mammal a T cell that expresses the present CAR. In one embodiment, the present disclosure includes a cellular therapy where T cells are genetically modified to express the present CAR and the CAR-T cell is administered (e.g., infused) to a subject/recipient in need thereof. The administered (e.g., infused) cell is able to kill tumor cells in the recipient. Unlike antibody therapies, CAR-T cells are able to replicate in vivo resulting in long-term persistence that can lead to sustained tumor control. In one embodiment, the CAR-T cells of the invention can undergo robust in vivo T cell expansion and can persist for an extended amount of time. In addition, the CAR mediated immune response may be part of an adoptive immunotherapy approach in which CAR-modified T cells induce an immune response specific to the antigen binding moiety in the CAR. For example, an anti-CD20 CAR-T cell elicits an immune response specific against cells expressing CD20. Although the data disclosed herein specifically disclose lentiviral vector comprising anti- CD20 scFv, hinge and transmembrane domain, and 4-1BB and CD3ζ signaling domains, the disclosure should be construed to include any number of variations for each of the components of the construct as described elsewhere herein. Diseases that may be treated using the present CAR, immune cells or pharmaceutical composition include CD20-positive tumors and diseases, e.g., caused by excessive B cells (such as autoimmune diseases, for example, lupus erythematosus, etc.). CD20 positive tumors may include CD20 positive non-solid tumors (such as hematological tumors, for example, leukemias and lymphomas) or solid tumors. Types of tumors or cancers to be treated with present CAR, immune cells or pharmaceutical composition include, but are not limited to, carcinoma, blastoma, and sarcoma, and certain leukemia or lymphoid malignancies, benign and malignant tumors, and malignancies e.g., sarcomas, carcinomas, and melanomas. Adult tumors/cancers and pediatric tumors/cancers are also included. Hematologic cancers are cancers of the blood or bone marrow. Examples of hematological (or hematogenous) cancers include leukemias, e.g., acute leukemias (such as acute lymphocytic leukemia, acute myelocytic leukemia, acute myelogenous leukemia and myeloblasts, promyeiocytic, myelomonocytic, monocytic and erythroleukemia), chronic leukemias (such as chronic myelocytic (granulocytic) leukemia, chronic myelogenous leukemia, and chronic lymphocytic leukemia), polycythemia vera, lymphoma, Hodgkin’s disease, non- Hodgkin’s lymphoma (indolent and high grade forms), multiple myeloma, Waldenstrom’s macroglobulinemia, heavy chain disease, myelodysplastic syndrome, hairy cell leukemia and myelodysplasia. Solid tumors are abnormal masses of tissue that usually do not contain cysts or liquid areas. Solid tumors can be benign or malignant. Different types of solid tumors are named for the type of cells that form them (such as sarcomas, carcinomas, and lymphomas). Examples of solid tumors, such as sarcomas and carcinomas, include fibrosarcoma, myxosarcoma, liposarcoma, mesothelioma, malignant lymphoma, pancreatic cancer and ovarian cancer. The CAR-modified T cells of the disclosure may also serve as a type of vaccine for ex vivo immunization and/or in vivo therapy in a mammal. Preferably, the mammal is a human. In certain embodiments, with respect to ex vivo immunization, at least one of the following occurs in vitro prior to administering the cell into a mammal: i) expansion of the cells, ii) introducing a nucleic acid encoding a CAR to the cells, and/or iii) cryopreservation of the cells. Ex vivo procedures are well known in the art and are discussed more fully below. Briefly, cells are isolated from a mammal (preferably a human) and genetically modified (i.e., transduced or transfected in vitro) with a vector expressing a CAR disclosed herein. The CAR-modified cell can be administered to a mammalian recipient to provide a therapeutic benefit. The mammalian recipient may be a human and the CAR-modified cell can be autologous with respect to the recipient. Alternatively, the cells can be allogeneic, syngeneic or xenogeneic with respect to the recipient. In addition to using a cell-based vaccine in terms of ex vivo immunization, the present disclosure also provides compositions and methods for in vivo immunization to elicit an immune response directed against an antigen in a patient. Generally, the cells activated and expanded as described herein may be utilized in the treatment and prevention of diseases that arise in individuals who are immunocompromised. In certain embodiments, the CAR-modified T cells are used in the treatment of CCL. In certain embodiments, the cells of the invention are used in the treatment of patients at risk for developing CCL. Thus, the present disclosure provides methods for the treatment or prevention of CCL comprising administering to a subject in need thereof, a therapeutically effective amount of the CAR-modified T cells. The CAR-modified T cells of the present disclosure may be administered either alone, or as a pharmaceutical composition in combination with diluents and/or with other components such as IL-2, IL-17 or other cytokines or cell populations. Briefly, pharmaceutical compositions of the present disclosure may comprise a cell population as described herein (e.g., immune cells expressing the CAR such as CAR-T cells), in combination with one or more pharmaceutically or physiologically acceptable carriers, diluents or excipients. Such compositions may comprise buffers such as neutral buffered saline, phosphate buffered saline and the like; carbohydrates such as glucose, mannose, sucrose or dextrans, mannitol; proteins; polypeptides or amino acids such as glycine; antioxidants; chelating agents such as EDTA or glutathione; adjuvants (e.g., aluminum hydroxide); and preservatives. Compositions of the present disclosure may be formulated for intravenous administration. Pharmaceutical compositions of the present disclosure may be administered in a manner appropriate to the disease to be treated (or prevented). The quantity and frequency of administration will be determined by such factors as the condition of the patient, and the type and severity of the patient’s disease, although appropriate dosages may be determined by clinical trials. When "an immunologically effective amount", "an anti-tumor effective amount", "an tumor-inhibiting effective amount", or "therapeutic amount" is indicated, the precise amount of the compositions of the present disclosure to be administered can be determined by a physician with consideration of individual differences in age, weight, tumor size, extent of infection or metastasis, and condition of the patient (subject). It can generally be stated that a pharmaceutical composition comprising the T cells described herein may be administered at a dosage of 10⁴ to 10⁹ cells/kg body weight, or 10⁵ to 10⁶ cells/kg body weight, including all integer values within those ranges. T cell compositions may also be administered multiple times at these dosages. The cells can be administered by using infusion techniques that are commonly known in immunotherapy (see, e.g., Rosenberg et al„ New Eng. J. of Med.319: 1676, 1988). The optimal dosage and treatment regime for a particular patient can readily be determined by one skilled in the art of medicine by monitoring the patient for signs of disease and adjusting the treatment accordingly. The administration of the compositions or cells may be carried out in any convenient manner, including by aerosol inhalation, injection, ingestion, transfusion, implantation or transplantation. The compositions described herein may be administered to a patient subcutaneously, intradermaliy, intratumorally, intranodally, intramedullary, intramuscularly, by intravenous (i.v.) injection, or intraperitoneally. In one embodiment, the compositions or cells of the present disclosure are administered to a patient by intradermal or subcutaneous injection. In another embodiment, the compositions or cells of the present disclosure are administered by i.v. injection. The compositions of T cells may be injected directly into a tumor, lymph node, or site of infection. In certain embodiments of the present disclosure, cells activated and expanded using the methods described herein, or other methods known in the art where T cells are expanded to therapeutic levels, are administered to a patient in conjunction with (e.g., before, simultaneously or following) any number of relevant treatment modalities, including but not limited to, treatment with agents such as antiviral therapy, cidofovir and interleukin-2, Cytarabine (also known as ARA-C) or natalizumab treatment for MS patients or efalizumab treatment for psoriasis patients or other treatments for PML patients. In further embodiments, the compositions or cells may be used in combination with chemotherapy, radiation, immunosuppressive agents, such as cyclosporin, azathioprine, methotrexate, mycophenolate, and FK506, antibodies, or other immunotherapeutic agents. In a further embodiment, the compositions or cells of the present disclosure are administered to a patient in conjunction with (e.g., before, simultaneously or following) bone marrow transplantation, or the use of chemotherapy agents such as, fludarabine, external-beam radiation therapy (XRT), cyclophosphamide. For example, in one embodiment, subjects may undergo standard treatment with high dose chemotherapy followed by peripheral blood stem cell transplantation. In certain embodiments, following the transplant, subjects receive an infusion of the expanded immune cells of the present disclosure. In an additional embodiment, expanded cells are administered before or following surgery. The dosage of the above treatments to be administered to a patient will vary with the precise nature of the condition being treated and the recipient of the treatment. The scaling of dosages for human administration can be performed according to art-accepted practices. In general, 1x10⁶ to 1x10¹⁰ of the modified T cells of the invention (e.g., CAR-T 20 cells) can be applied to patients by means of, for example, intravenous infusion each treatment or each course of treatment. The advantages of the certain embodiments of the present disclosure include: (1) As for the chimeric antigen receptor of the present disclosure, the extracellular antigen binding domain thereof is a specific anti-CD20 scFv. The CAR formed by binding the specific anti-CD20 scFv to a specific hinge region and an intracellular domain shows a great capability of killing tumor cells with low cytotoxicity and low side effects. (2) The chimeric antigen receptor provided by the disclosure can achieve stable expression and membrane localization of CAR protein after T cells is infected by lentivirus carrying CAR gene. (3) The CAR-modified T cell of the present disclosure has a longer survival time in vivo and strong anti-tumor efficacy. The optimized CAR with the IgG4 Hinge-CH2-CH3 linker region can avoid the binding of the Fc receptor and the subsequent ADCC effect (antibody- dependent cytotoxicity). The term "about" may refer to a value or composition within an acceptable error range for a particular value or composition as determined by those skilled in the art, which will depend in part on how the value or composition is measured or determined. The term “about” in reference to a numeric value may refer to ±10% of the stated numeric value. In other words, the numeric value can be in a range of 90% of the stated value to 110% of the stated value. The term "administering" refers to the physical introduction of a product of the disclosure into a subject using any one of various methods and delivery systems known to those skilled in the art, including, but not limited to, intravenous, intramuscular, subcutaneous, intraperitoneal, spinal or other parenteral administration, such as by injection or infusion. The following examples of specific aspects for carrying out the present invention are offered for illustrative purposes only, and are not intended to limit the scope of the present invention in any way. Example 1 Construction of lentiviral expression vector The full-length DNA synthesis and cloning construction of coding plasmids were conducted. Different anti-CD20 scFv coding sequences were used in each plasmid. The cloning vector was selected as pWPT lentiviral vector. The cloning sites were BamH I and Sal I sites. The specific sequence structure is shown in Figure 1. The amino acid and nucleotide sequences of each element are as described above. In the following examples, CAR-T20.13, CAR-T20.14, CAR-T20.16, CAR-T20.19, CAR-T20.20 with better effects are taken as examples. Example 2 Preparation of CAR-T cell (1) After taking venous blood from healthy subjects, mononuclear cells (PBMCs) were isolated by density gradient centrifugation. (2) On day 0, PBMCs were cultured in GT-T551 cell culture medium containing 2% human albumin, and the final concentration of cells was adjusted to 2x10⁶ cells/mL. The cells were seeded in a cell culture flask previously coated with Retronectin (purchased from TAKARA) at a final concentration of 10 μg/mL and CD3 monoclonal antibody (OKT3) at a final concentration of 5 μg/mL. Recombinant human interleukin 2 (IL-2) was added to the culture medium at a final concentration of 1000 U/mL. The cells were cultured in an incubator with a saturated humidity and 5% CO₂ at 37 °C. (3) On day 2, fresh medium, concentrated and purified CAR20 lentivirus solution, protamine sulfate (12 μg/ml), and IL-2 (at a final concentration of 1000 U/mL) were added. After 12 hours of infection in a 5% CO₂ incubator at 37 °C, the culture medium was discarded, fresh medium was added, and cultivation was continued in a 5% CO₂ incubator at 37 °C. (4) Starting from day 6, CART20 cells can be taken for the corresponding activity assay. In the present disclosure, the preparation process of CAR-modified T cell targeting CD20 antigen was improved, and GT-551 serum-free medium supplemented with 2% human albumin was selected to culture lymphocytes in vitro. Example 3 Detection of the integration rate of the CAR gene in the T cell genome and the expression level of the encoded protein thereof on the membrane surface. 0.5x10⁶ of CART-20 cell samples cultured on day 7 (Fig.2A and Fig.5A) and day 11 (Fig.2B) in Example 2 were taken, respectively. The expression level of CAR20 protein on the surface of T cell membrane was analyzed by flow cytometry after Protein L staining. The results showed that, except for CAR-T20.13, all of the CAR structures designed in this study can detect the chimeric antigen receptor localization on the cell membrane surface of the corresponding modified T cells using Protein L. Example 4 Detection of the in vitro activation ability of CAR-T20s The deCAR-T20 cells cultured on day 6 in Example 2 were co-cultured with target cells. Then the up-regulated level of CD137 and the secretion level of IFNγ in the culture supernatant were examined.1x10⁵ of CART-20 cells (cultured on day 6) were cultured respectively with CD20-positive RAJI and RAMOS tumor cell lines, and CD20-negative MOLT-4 tumor cell line, or without tumor cells, in 200 μl GT-551 medium for 18h in a ratio of 1:1. Then the expression level of CD137 on the surface of T cell membrane was detected by flow cytometry (Fig.3A) and the secretion level of IFNγ in the culture supernatant was detected by ELISA (Fig.3B). From the results in Figures 3A-3B, we could concluded that the CAR based on Obinutuzumab also achieved expression and membrane surface localization in the corresponding modified cells, but the CAR structure based on the Ofatumumab sequence showed better in vitro activation ability and specificity targeting antigen when compared with the CAR constructed based on Obinutuzumab and Rituximab. Example 5 Detection of the CAR-T20s cells induced early apoptosis activity of tumor cells CART-20.13, CART-20.14 and CAR-T20.16 cells (cultured on day 11) from Example 2 were co-cultured respectively with 1x10⁴ of CFSE-labeled CD20-negative (MOLT-4) or CD20- positive (RAJI, RAMOS) tumor cell lines in 200 μl GT-551 medium for 4h. Then the cell pellet was collected by centrifugation. The cells were washed twice with PBS and stained for 30 min with Annexin V-APC dye in a ratio of 1:50 in 100 μl of dyeing solution. After washing with PBSonce, the proportion of Annexin V positive cells in CFSE positive cells was analyzed on a flow cytometry. The results in Figure 4 show that the CAR structure based on the Ofatumumab sequence shows better ability to induce early apoptosis of CD20 target cells in vitro when compared with the CAR constructed based on Obinutuzumab and Rituximab. Example 6 Identification of the in vitro activation ability of the third-generation chimeric antigen receptor and the chimeric antigen receptor with mutation in hinge region (1) Under the condition that the transfection rate was basically equal (Fig.5A), the CAR- T20s cells (prepared by the method of Example 2) cultured on the day 7 were cultured respectively with K562, K562 stable transfected cells of CD19 single positive, CD20 single positive, CD19 and CD20 double positive, and RAJI target cell ( each taking 1x10⁵ cells) in 200 μl GT-551 medium for 18h in a ratio of 1:1. Then the up-regulated level of CD137 (Fig.5B) and the secretion level of IFNγ in the culture supernatant (Fig.5C) were detected. (2) The results shown in Figure 5 indicate that the in vitro activation ability (CD137 and IFNg) of the chimeric antigen receptor CAR-T20.14 and CAR-T20.19 (having a mutation in the hinge region) is substantially equivalent, in the case of substantially identical infection efficiency. The third generation CAR structure CAR-T20.20 shows better in vitro activation capacity (CD137 and IFNγ) than the second-generation CAR-T20.14 and CAR-T20.19. Example 7 Detection of the ability of CAR-T20 cells to scavenge CD20 positive cells in vivo (1) Raji-Luc cells expressing luciferase were injected into NCG mice (5x10⁵/ mouse) through the tail vein. One week after the inoculation, the in vivo expansion of the tumor cells was observed by in vivo imaging and recorded as Day 0. NT and CAR-T20.19 cells were injected into Day 0 mice (5x10⁶/mouse) through the tail vein. On Day0, Day7, Day14, Day21, the expansion of tumor cells in mice was observed by in vivo imaging and analyzed based on changes in fluorescence intensity and body weight changes of mice. (2) The results shown in Figure 6 indicate that CAR-T20.19 can effectively inhibit the in vivo expansion of CD20-positive tumor cells. Example 8 We prepared two anti-CD20 CARs having the same V_H (SEQ ID NO: 7) and V_L (SEQ ID NO: 11) but in different orders: CAR-T20.19 (SEQ ID No.5) has V_H -V_L (i.e., V_H is located at the N-terminus of V_L), while CAR-T20.29 has V_L-V_H (Figure 9A). As shown in Figure 9B, CAR-T20.19 (V_H -V_L) demonstrated significantly higher in vitro activities (e.g., inducing interferon-γ or IFN-γ release) against the CD20-positive cells than CAR-T20.29 (V_L-V_H). Specifically, CAR-T20.19 (V_H -V_L) showed 190%, 80%, and 38% greater activities compared to CAR-T20.29 (V_L-V_H) for the CD20-positive cell lines K562-CD20, A549-CD20, and Raji, respectively. Thus, the order of V_H and V_L directly impacts the function of the CAR T cells. CARs having the V_H -V_L structure (e.g., CAR-T20.19) demonstrated significantly higher in vitro activities than CARs having the reversed V_L - V_H structure (e.g., CAR-T20.29). Example 9 Our studies demonstrated that CAR-T20.19 was considerably more cytotoxic towards tumor cells both in vitro and in vivo, compared to CAR-T cells based on another anti-CD20 antibody, Leu16. Figures 8B-8C show CAR-T20.19 induced higher levels of IFN-γ release and greater cell killing in CD20-positive tumor cells, including RAJI and RAMOS, compared to CART20-Leu. For in vivo studies, NSG mice were xenografted with Raji-Luc cells which are human Burkitt’s lymphoma Raji cells expressing firefly luciferase as a reporter. Different CAR-T cells or negative control were then administered to the mice. The fluorescence intensity of the animals xenografted with Raji-Luc were assayed after treatment, which reflected the proliferation of tumor cells in the animals. Figure 8D shows that the fluorescence intensities in the mice administrated with CART20-OF(2nd) (CAR-T20.19) T cells were markedly lower than mice administered with CART20-LEU (2nd) or CART20-LEU (3rd). The results suggest that CAR- T20.19 had higher in vivo anti-tumor efficacy than the other CARs. The above in vitro and in vivo data prove that, compared with CAR-T cells with other scFv sequences, CART20-OF(2nd) (CAR-T20.19) possesses superior anti-tumor efficacy both in vitro and in vivo. Example 10 B-cell lymphomas can be stratified into Hodgkin lymphoma (~10% of all cases) and non- Hodgkin lymphoma (NHL; ~90% of all cases), both of which comprise many subtypes. For relapsed and refractory NHL, the response rates to conventional salvage chemotherapy are approximately 40–50%. NHL subtypes include indolent forms, such as follicular lymphoma (FL), and aggressive forms, such as diffuse large B-cell lymphoma (DLBCL). Standard therapies for lymphoma include combination immunotherapy/chemotherapy, radiation therapy, and hematopoietic stem cell transplant (HSCT). NHL is associated with high mortality and a poor prognosis. The prognosis for patients with DLBCL is even grimmer, where the overall survival is 6.3 months from the last treatment failure. A study reported 43% overall response rate (ORR) in patients with DLBCL and 71% ORR in those with FL at 6 months after anti-CD19 CAR-T cell infusion. See, Lulla et al., The Use of Chimeric Antigen Receptor T Cells in Patients with Non-Hodgkin Lymphoma, Clinical Advances in Hematology & Oncology, 2018, 16(5): 375- 386. We conducted a clinical trial of CAR-T20.19 (also termed “C-CAR066”) in treating relapsed/refractory DLBCL (R/R DLBCL) in patients who were released from the anti-CD19 CAR-T treatment and had one or more relapses prior to our CAR-T20.19 clinical trial. These patients had very poor clinical outcome. Specifically, ten (10) patients were enrolled. The patients’ baseline demographics and clinical characteristics prior to the start of our anti-CD20 CAR treatment are shown in Table 1. Table 1 Summary of demographic and baseline clinical characteristics of the patients The clinical protocol, as well as the key inclusion criteria, is shown in Figure 12. Specifically, the patients were screened 21 days before the treatment (-21d). Qualified subjects were enrolled, and peripheral blood leukocytes collected. The collected peripheral blood leukocytes were used to produce the CAR-T cells (CAR-T20.19). The CAR-T cells were then frozen and stored until use. For CAR-T treatment, the CAR-T cells were thawed, and administration completed within 30-45 minutes. At -5, -4 and -3 days before the CAR-T infusion, the patients received lymphodepletion pretreatment, including fludarabine (30 mg/m²/d, intravenous, once per day for three days), and cyclophosphamide (300 mg/m²/d, intravenous, once per day for three days). Approximately 72 hours after lymphodepletion, the patients were administered 2.0 x 10⁶, 3.0 x 10⁶ or 4.8 x 10⁶ CAR-T cells/kg on day 0 as a single infusion. Follow-ups with the patients were carried out from day 1 to month 24 (e.g., day 4, day 7, day 10, week 2, week 3, week 4, etc.) after the infusion. The first clinical response assessment was at week 4 after the CAR-T infusion. For our clinical trial of CAR-T20.19, the Kaplan Meier progression-free survival (PFS) estimates include a 6-month PFS of 57.1%, with 95% confidence intervals (CIs) of ~30% - 100%. See Table 2 and Figure 14B. Table 2 The tumor burden in the patients decreased significantly (Figure 14C). The patients’ adverse reactions (treatment-emergent adverse events, TEAE) were recorded (Table 3 and Table 4). There was only 1 (10.0%) grade ≥ 3 cytokine release syndrome (CRS). No neurotoxicity was observed in the patients. Cytopenia, such as neutropenia and thrombocytopenia, was mostly related to the fludarabine/cyclophosphamide (Cy/Flu) lymphodepletion. The cytopenia was also reversible. These demonstrated that our anti-CD20 CAR had an excellent safety profile. Table 3 ¹ CRS: uniformly graded according to the ASTCT Guidelines. See, Lee, Biol Blood Marrow Transplant, 2019, 25: 625. Table 4 8 out of 10 patients had grade 1-2 CRS, while 1 out of 10 patients had grade 4 CRS. This patient presented with high fever, hypotension and hypoxia on day 6 and resolved on day 10. The patient was treated with tocilizumab and steroids, and with non-invasive ventilation support. The patient was not admitted to the ICU. There had not been ICANS events. See also, Figure 13. Cytopenias mostly related to Cy/Flu lymphodepletion which were reversible. As shown in Figure 14A and Table 5, an overall response rate (ORR, including CR and PR) of our anti-CD20 CAR-T trial is 100%. The best response included 7 CRs (70.0%) and 3 PRs. Table 5 * Assessed by investigators. NR: not reached. As shown in Figure 14A, ORR rate was 100% and CR rate was 70%. The median time to first response was 1 month (range, 0.9-2.7). The median time to CR as 2.7 months (range, 0.9- 2.9). Median follow-up was 4.2 months (range is 1.2-11.7). Median DOR has not been reached. 4 patients remained in CR after 10 months. The time course of the CAR copies in the blood of the patients is shown in Figure 16A. Thus, the CAR levels were maintained in the blood after administration. The PET-CT images of the cancer lesions for one patient, patient No.2, are shown in Figure 15B. It clear shows that the tumor lesions decreased significantly in size three months after the anti-CD20 CAR T treatment. CD19/CD20 expression tested in tumor tissues by IHC is shown in Table 6. Table 6 The aggressive forms of lymphomas, such as DLBCL, are less susceptible to T cell- mediated immune effects than indolent lymphomas. Thus, the fact that CAR-T20.19 achieved 100% overall response rate (ORR) and 70.0% complete response rate (CR) in treating R/R DLBCL, after post-anti-CD19 CAR-T treatment relapses, with a single administration is notable. To summarize, CAR-T20.19 offered superior therapeutic efficacy in a clinical trial, with high response rates (100% ORR and 70.0% CR) in treating relapsed/refractory non-Hodgkin lymphoma (R/R NHL) and a favorable safety profile. The remarkable 100% ORR and 70.0% CR were achieved after only a single administration of the anti-CD20 CAR T cells. Preclinical studies suggest that C-CAR066 has optimal structure and superior anti-tumor activity compared to anti-CD20 CAR-Ts derived from scFvs of Leu16, Rituximab, and Obinutuzumab and anti-CD19 CAR-T. In the clinical study, C-CAR066 shows a favorable safety profile and very promising efficacy in patients with r/r NHL following CD19 CAR-T therapy (with a median DOR of 2.1 months) compared to CD20/CD3 bispecific antibody. Example 11 In one case study, a 67-year-old male with double-expressor DLBCL was diagnosed in May 2019. The patient had 4 prior lines of therapy, including anti-CD19 CAR-T treatment. The patient had right and left calve lesions. The patient’s bulky disease was 25.9 *6.3*10.1 cm in the right leg at baseline. The prior anti-CD19 CAR-T treatment had a best response of PR and duration of response of 1.2 months. The C-CAR066 treatment included 3.0x10⁶/kg dosage, grade 2 CRS (onset on day 2, resolved on day 11), no neurotoxicity. CR was achieved by day 27 (Figure 15A). The scope of the present invention is not limited by what has been specifically shown and described hereinabove. Those skilled in the art will recognize that there are suitable alternatives to the depicted examples of materials, configurations, constructions and dimensions. Numerous references, including patents and various publications, are cited and discussed in the description of this invention. The citation and discussion of such references is provided merely to clarify the description of the present invention and is not an admission that any reference is prior art to the invention described herein. All references cited and discussed in this specification are incorporated herein by reference in their entirety. Variations, modifications and other implementations of what is described herein will occur to those of ordinary skill in the art without departing from the spirit and scope of the invention. While certain embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the spirit and scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only and not as a limitation.

Claims

Claims 1. A chimeric antigen receptor (CAR), comprising: an anti-CD20 antigen-binding region which comprises a heavy chain variable region (V_H) and a light chain variable region (V_L), V_H comprising three CDRs, HCDR1, HCDR2 and HCDR3, V_L comprising three complementarity determining regions (CDRs), LCDR1, LCDR2 and LCDR3, (a) wherein HCDR1, HCDR2 and HCDR3 have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 41, SEQ ID NO: 42, SEQ ID NO: 43, respectively, wherein LCDR1, LCDR2 and LCDR3 have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 44, SEQ ID NO: 45, SEQ ID NO: 46, respectively; (b) wherein HCDR1, HCDR2 and HCDR3 have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 48, SEQ ID NO: 50, SEQ ID NO: 52, respectively, wherein LCDR1, LCDR2 and LCDR3 have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 55, SEQ ID NO: 57, SEQ ID NO: 59, respectively; or (c) wherein HCDR1, HCDR2 and HCDR3 have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 62, SEQ ID NO: 64, SEQ ID NO: 66, respectively, wherein LCDR1, LCDR2 and LCDR3 have amino acid sequences about 80% to about 100% identical to the amino acid sequences set forth in SEQ ID NO: 69, SEQ ID NO: 71, SEQ ID NO: 73, respectively.

2. The CAR of claim 1, wherein V_H is located at the N-terminus of V_L.

3. The CAR of claim 1, wherein V_H and V_L have amino acid sequences about 80% to about 100% identical to amino acid sequences set forth in (a) SEQ ID NO: 7 and SEQ ID NO: 11, respectively; (b) SEQ ID NO: 9 and SEQ ID NO: 13, respectively; or (c) SEQ ID NO: 33 and SEQ ID NO: 35, respectively.

4. The CAR of claim 1, wherein the anti-CD20 antigen-binding region is a single-chain variable fragment (scFv) that specifically binds CD20.

5. The CAR of claim 1, wherein the CAR further comprises one or more of the following: (a) a signal peptide, (b) a hinge region, (c) a transmembrane domain, (d) a co-stimulatory region, and (e) a cytoplasmic signaling domain.

6. The CAR of claim 5, wherein the co-stimulatory region comprises a co-stimulatory region of 4-1BB (CD137), CD28, or combinations thereof.

7. The CAR of claim 5, wherein the cytoplasmic signaling domain comprises a cytoplasmic signaling domain of CD3ζ.

8. The CAR of claim 5, wherein the hinge region comprises a hinge region of CD8, CD28, CD137, IG4, or combinations thereof.

9. The CAR of claim 5, wherein the transmembrane domain comprises a transmembrane domain of CD8, CD28, or combinations thereof.

10. The CAR of claim 1, comprising an amino acid sequence about 80% to about 100% identical to the amino acid sequence set forth in SEQ ID NO: 1, SEQ ID NO: 3, SEQ ID NO: 5, SEQ ID NO: 29, or SEQ ID NO: 31.

11. The CAR of claim 5, wherein the hinge region comprises an amino acid sequence about 80% to about 100% identical to the amino acid sequence set forth in SEQ ID NO: 17, or SEQ ID NO: 19.

12. The CAR of claim 5, wherein the transmembrane domain comprises an amino acid sequence about 80% to about 100% identical to the amino acid sequence set forth in SEQ ID NO: 21.

13. The CAR of claim 5, wherein the cytoplasmic signaling domain comprises an amino acid sequence about 80% to about 100% identical to the amino acid sequence set forth in SEQ ID NO: 25.

14. The CAR of claim 5, wherein the co-stimulatory region comprises an amino acid sequence about 80% to about 100% identical to the amino acid sequence set forth in SEQ ID NO: 23, or SEQ ID NO: 39.

15. An immune cell expressing the CAR of claim 1.

16. The immune cell of claim 15, wherein the immune cell is a T cell or a natural killer (NK) cell.

17. A pharmaceutical composition comprising the immune cell of claim 15.

18. A nucleic acid encoding the CAR of claim 1.

19. A vector comprising the nucleic acid of claim 18.

20. A method of treating cancer, the method comprising administering the immune cell of claim 15 to a subject in need thereof.

21. The method of claim 20, wherein the cancer is a hematologic cancer.

22. The method of claim 20, wherein the cancer is a B-cell malignancy.

23. The method of claim 20, wherein the cancer is Hodgkin's lymphoma, non-Hodgkin's lymphoma, leukemia, and/or multiple myeloma (MM).

24. The method of claim 22, wherein the B-cell malignancy is acute lymphocytic leukemia (ALL), chronic lymphocytic leukemia (CLL), B-cell acute lymphoblastic leukemia (B-ALL), B- cell leukemia, or B cell lymphoma.

25. The method of claim 20, wherein the immune cell is administered by infusion, injection, transfusion, implantation, and/or transplantation.

26. The method of claim 20, wherein the immune cell is administered intravenously, subcutaneously, intradermally, intranodally, intratumorally, intramedullary, intramuscularly, or intraperitoneally.

27. The method of claim 20, wherein the immune cell is administered via intravenous infusion.

28. The method of claim 20, wherein the immune cell is allogeneic or autologous.

29. The method of claim 20, wherein the subject is a human.

30. A method for treating cancer, the method comprising administering the immune cell of claim 15 to a subject in need thereof, wherein the chimeric antigen receptor (CAR) generates an area under the curve (AUC) ranging from about 1.0e+05 copies/µg genomic DNA (copies/gDNA) to about 1.1e+07 copies/gDNA in the blood of the subject in about 28 days after administration.

31. The method of claim 30, wherein the AUC ranges from about 2.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.1e+07 copies/gDNA in the blood of the subject in about 28 days after administration.

32. The method of claim 30, wherein the AUC ranges from about 1.0e+05 copies/µg genomic DNA (copies/gDNA) to about 4.0e+06 copies/gDNA in the blood of the subject in about 28 days after administration.

33. The method of claim 30, wherein the AUC ranges from about 1.0e+06 copies/µg genomic DNA (copies/gDNA) to about 1.0e+07 copies/gDNA in the blood of the subject in about 28 days after administration.

34. A method for treating cancer, the method comprising administering the immune cell of claim 15 to a subject in need thereof, wherein the chimeric antigen receptor (CAR) generates a maximum plasma concentration (C_max) ranging from about 1.0e+04 copies/µg genomic DNA (copies/gDNA) to about 1.1e+06 copies/gDNA in the blood of the subject.

35. The method of claim 34, wherein the C_max ranges from about 1.0e+04 copies/µg genomic DNA (copies/gDNA) to about 3.0e+05 copies/gDNA in the blood of the subject in about 28 days after administration.

36. The method of claim 35, wherein the C_max ranges from about 2.0e+05 copies/µg genomic DNA (copies/gDNA) to about 1.1e+06 copies/gDNA in the blood of the subject in about 28 days after administration.

37. The method of claim 35, wherein the CAR has a T_max ranging from about 10 days to about 25 days.

38. The method of claim 35, wherein the CAR has a T_max ranging from about 10 days to about 20 days.

39. The method of claim 35, wherein the CAR has a T_max ranging from about 12 days to about 15 days.