CD19 Chimeric Antigen Receptor (CAR): A Comprehensive Guide and Our Service & Product Introduction

With the continuous development of CAR-T cell therapy, CD20 CAR has become a research hotspot in the field of immunotherapy. Our company keeps pace with the latest research trends, continuously optimizes product performance, and updates product types to provide customers with the most advanced and reliable CD20 CAR plasmid vector products and services. Whether you are engaged in basic research on CD20 CAR or preclinical evaluation, we can provide you with professional support and high-quality products.

Our CD20 CAR expression plasmid vectors are widely used in academic research and pharmaceutical R&D, supporting researchers and pharmaceutical companies to accelerate the progress of CD20 CAR-based immunotherapy. We adhere to the principle of "quality first, customer-oriented", and provide one-stop services from standard products to customized solutions, helping customers solve the key technical problems in CD20 CAR research.

Our CD20 CAR Expression Plasmid Vector Products and Custom Services

As a professional provider of gene editing and vector construction services, our company is committed to providing high-quality CD20 CAR expression plasmid vector products and customized vector construction services to support the research and development of CD20 CAR-based immunotherapy. Our products cover different generations of CD20 CAR, with comprehensive features, reliable quality, and wide applicability, meeting the diverse needs of researchers.

Product Features

1) Diverse and optimized promoters: We provide a variety of promoters to meet different expression needs, including constitutive promoters (CMV, EF1α, CAG etc.) and inducible promoters (Tet-on, Cre-loxP). EF1α promoter is widely used for high-efficiency and stable expression of CD20 CAR in various immune cells (T cells, NK cells), while inducible promoters can achieve conditional expression of CD20 CAR, improving the safety of therapy and facilitating the study of CAR function.

2) Multiple fluorescent labeling options: The plasmid vectors are integrated with fluorescent reporter genes, such as EGFP (enhanced green fluorescent protein). The fluorescent label can be used to monitor the transfection efficiency of the plasmid, the expression level of CD20 CAR, and the tracking of CAR-expressing cells in vitro and in vivo, facilitating the observation and analysis of experimental results.

3) Flexible antibiotic selection markers: We offer a variety of mammalian antibiotic selection markers, such as puromycin (Puro). Customers can choose the appropriate selection marker according to the host cells and experimental needs, ensuring efficient screening of positive clones and stable expression of the plasmid.

4) Optimized CAR structure: The CD20 scFv in our plasmid vectors is derived from high-affinity and high-specificity anti-CD20 monoclonal antibodies, which can specifically bind to CD20 antigen with low off-target rate. The transmembrane domain and intracellular signaling domain are optimized to enhance the stability of CAR expression and the activation efficiency of immune cells. Additionally, the vector backbone is optimized to reduce the probability of gene rearrangement and improve the transfection efficiency and expression stability in mammalian cells.

Product Advantages

1) High quality and reliability: All CD20 CAR plasmid vectors are subject to strict quality control, ensuring stable CAR expression. Upon request, we can provide endotoxin free plasmid vectors, which can avoid affecting the activity of immune cells and the accuracy of experimental results.

2) Comprehensive coverage: Covering multiple generations of CD20 CAR, and providing multiple options for promoters, fluorescent labels, and antibiotic selection markers, which can meet the diverse needs of research.

3) Easy to use: The plasmid vectors are designed with a simple and clear structure, and are compatible with common transfection methods (liposome transfection, electroporation, viral packaging).

4) Cost-effective: We provide high-quality products at competitive prices, and offer bulk purchase discounts to reduce the research costs of customers. At the same time, the stable performance of the products can reduce the repetition of experiments and improve research efficiency.

5) Customizable optimization: On the basis of standard products, we can carry out personalized optimization according to the specific needs of customers, such as adding specific functional modules, or adjusting the vector backbone, to meet the special research needs of customers.

Product Applications

1) Basic research: Study the mechanism of CD20 CAR-mediated immune cell activation, the structure-activity relationship of CAR, and the interaction between CD20 CAR and target cells.

2) Preclinical research: Construct CD20 CAR-T/NK cells in vitro, evaluate their anti-tumor activity and safety in cell models and animal models (such as mouse models of B-cell lymphoma), and lay a foundation for clinical trials.

3) Development of new CAR technologies: Used for the research and development of bispecific/multispecific CD20 CAR, armored CD20 CAR, and in vivo CAR delivery systems.

Custom CAR Plasmid Vector Construction Services

In addition to standard CD20 CAR expression plasmid vectors, we also provide professional customized vector construction services to meet the personalized research needs of customers. Our customized services have the advantages of fast construction cycle, high success rate, and strict quality control, which can help customers accelerate the progress of CD20 CAR research and development.

1) Customized CAR structure design: According to the customer's research needs, design and construct CD20 CAR plasmid vectors with specific structures, such as bispecific/multispecific CAR (CD20+CD19, CD20+CD22), armored CAR (adding IL-12, IL-15, PD-1 blockade, etc.).

2) Customized vector backbone modification: Modify the vector backbone according to the customer's needs, such as changing the promoter, or optimizing the vector for viral packaging (lentivirus, retrovirus) to improve the efficiency of viral transduction.

3) Customized labeling and selection markers: Add specific fluorescent labels (such as EGFRP, luciferase) or antibiotic selection markers according to the customer's experimental needs, facilitating the tracking and screening of CAR-expressing cells.

4) Full-process technical support: Our professional technical team provides full-process technical support from CAR structure design, vector construction, quality control, to experimental guidance, ensuring that the customized products meet the customer's research needs and helping customers solve problems encountered in the experimental process.

Introduction of CD20

CD20, also known as MS4A1 (Membrane-Spanning 4-Domain Subfamily A Member 1), is a non-glycosylated transmembrane protein specifically expressed on the surface of B lymphocytes. It was first identified as a B-cell differentiation antigen in the 1980s and has since become a key target for the treatment of B-cell-related diseases, especially B-cell malignancies and autoimmune diseases. Its unique expression pattern - highly expressed in most B-cell lineage cells but absent in hematopoietic stem cells and plasma cells - makes it an ideal target for targeted therapies, as it can specifically eliminate pathogenic B cells while minimizing damage to normal hematopoietic function and immune homeostasis.

The human CD20 gene (MS4A1) is located on chromosome 11q12-q13.1, spanning approximately 16 kilobases (kb) and consisting of 8 exons. It encodes a protein of 297 amino acid residues with a molecular weight of 33-37 kDa. The MS4A1 gene is evolutionarily conserved across species, and its expression is tightly regulated during B-cell development, being activated in pre-B cells and maintained throughout the mature B-cell stage, then downregulated in terminally differentiated plasma cells. Abnormal expression or mutation of the MS4A1 gene is closely associated with the occurrence and progression of B-cell malignancies, such as chronic lymphocytic leukemia (CLL) and diffuse large B-cell lymphoma (DLBCL).

CD20 is a member of the MS4A protein family and exhibits a typical four-transmembrane domain (TMD) structure. Its structure consists of four hydrophobic transmembrane domains, one intracellular domain, and two extracellular domains (a large loop and a small loop), with both the N-terminus and C-terminus located in the cytoplasm. CD20 does not form heterooligomers but exists on the cell surface as homodimers or homotetramers, which interact with other cell surface and cytoplasmic proteins to participate in signal transduction. Three subtypes of CD20 (33, 35, and 37 kDa) have been identified, which are generated by different phosphorylation events and play distinct roles in B-cell signaling.

CD20 plays a crucial role in the regulation of B-cell development, differentiation, activation, and survival. Its core function is to participate in the calcium influx required for B-cell antigen receptor (BCR) signaling, which is essential for B-cell growth, differentiation, and activation. CD20 mediates calcium entry through store-operated calcium entry (SOCE) and regulates B-cell proliferation, differentiation, and antibody production by interacting with multiple surface proteins. Additionally, CD20 is involved in the regulation of B-cell responses to antigens and plays a key role in maintaining B-cell homeostasis in the immune system. Dysfunction of CD20 can lead to abnormal activation of B cells, thereby contributing to the development of B-cell malignancies and autoimmune diseases.

CD20 is specifically expressed in the B-cell lineage, with expression starting from the pre-B cell stage and persisting through the mature B cell stage. It is highly expressed in more than 95% of B-cell lymphomas but rarely present in other normal tissues, which is the basis for its status as an ideal therapeutic target. Specifically, CD20 is expressed in B cells in the bone marrow, peripheral blood, lymph nodes, spleen, and other lymphoid tissues. Notably, it is not expressed in hematopoietic stem cells, plasma cells, or other non-B cells (such as T cells, natural killer cells, and epithelial cells), ensuring that targeted therapies against CD20 can selectively eliminate pathogenic B cells without affecting normal tissue function.

CD20 is closely associated with two major categories of diseases: B-cell malignancies and autoimmune diseases.

1) B-cell malignancies: This is the most well-established application field of CD20-targeted therapies. CD20 is highly expressed in various B-cell malignancies, including diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), chronic lymphocytic leukemia (CLL), mantle cell lymphoma (MCL), and marginal zone lymphoma (MZL). The high specificity of CD20 expression makes it a core target for the treatment of these diseases.

2) Autoimmune diseases: Abnormal activation of B cells is a key pathogenic mechanism of many autoimmune diseases, and CD20, as a key regulator of B-cell function, is closely involved in the occurrence and development of these diseases. CD20-targeted therapies have shown significant efficacy in the treatment of autoimmune diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and multiple sclerosis (MS). For example, obinutuzumab (a CD20 monoclonal antibody) has been proven to significantly improve the complete renal remission rate in patients with lupus nephritis, bringing new hope for the treatment of this disease.

Introduction of CD20 Chimeric Antigen Receptor (CAR)

Chimeric Antigen Receptor (CAR) is an artificially designed transmembrane protein that can redirect T cells (or other immune cells) to specifically recognize and kill target cells expressing a specific antigen. CD20 CAR is a type of CAR that targets the CD20 antigen, which is constructed by fusing three core domains: an extracellular antigen-binding domain (usually a single-chain variable fragment, scFv, derived from a CD20-specific monoclonal antibody), a transmembrane domain, and an intracellular signaling domain. When CD20 CAR-expressing immune cells encounter CD20-positive target cells, the scFv specifically binds to CD20, triggering the intracellular signaling domain to activate the immune cells, thereby inducing the killing of target cells. CD20 CAR-based immunotherapy has become a promising strategy for the treatment of CD20-positive B-cell malignancies and autoimmune diseases, overcoming the limitations of traditional chemotherapy and monoclonal antibody therapies.

Since the first CD20 CAR was reported in the 1990s, significant progress has been made in its research and development. With the continuous optimization of CAR structure and the improvement of cell engineering technology, CD20 CAR has evolved from the first generation to the fourth (and even fifth) generation, and its therapeutic efficacy and safety have been continuously improved. In recent years, clinical trials of CD20 CAR-T cell therapy have achieved encouraging results, especially in the treatment of relapsed/refractory (R/R) B-cell non-Hodgkin lymphoma (NHL). For example, a phase I dose-escalation trial of autologous CD19/CD20 bispecific CAR-T cells showed a 90% overall response rate (ORR) and 70% complete response (CR) rate in R/R B-NHL patients, demonstrating strong therapeutic potential. Additionally, CD20 CAR-NK cell therapy and CD20 CAR-macrophage therapy are also in the preclinical and early clinical research stages, providing new options for the treatment of CD20-positive diseases.

1) First-generation CD20 CAR plasmid vector: Contains only the CD3ζ intracellular signaling domain. It can mediate the activation of T cells and kill CD20-positive target cells, but lacks co-stimulatory signals, resulting in weak T-cell proliferation ability and short persistence. Suitable for basic research on CD20 CAR mechanism.

2) Second-generation CD20 CAR plasmid vector: Adds one co-stimulatory domain (CD28 or 4-1BB) to the first-generation structure, which can significantly enhance the proliferation, activation persistence, and anti-tumor activity of T cells. It is the most widely used type in current CD20 CAR research and preclinical trials, and is also the basis for the development of clinical-grade CAR-T cells.

3) Third-generation CD20 CAR plasmid vector: Adds two co-stimulatory domains (such as CD28+4-1BB, CD28+OX40) to further enhance the anti-tumor activity and persistence of CAR-T cells, and reduce T-cell exhaustion. Suitable for research on improving the long-term efficacy of CD20 CAR therapy.

4) Fourth-generation CD20 CAR plasmid vector (also known as armored CAR): On the basis of the third-generation structure, it adds cytokine modules (such as IL-12, IL-15) or immune checkpoint inhibitor modules (such as PD-1 blockade). It can regulate the tumor microenvironment, enhance the anti-tumor activity of CAR-T cells, and overcome the immunosuppressive microenvironment of tumors. Suitable for research on overcoming the limitations of traditional CD20 CAR therapy in solid tumors or relapsed/refractory diseases.

Approved Drugs

To date, no CD20 CAR-T cell therapy product has been officially approved for marketing globally, but a number of CD20-targeted therapies (including monoclonal antibodies and radioimmunoconjugates) have been approved, laying a foundation for the development of CD20 CAR therapy. Meanwhile, CD20 CAR-T cell therapies are in advanced clinical trials, and some have shown excellent efficacy. Key approved CD20-targeted drugs include:

1) Rituximab: The first-generation chimeric anti-CD20 monoclonal antibody, approved by the FDA in 1997 for the treatment of B-cell NHL, CLL, and other diseases. It is widely used in clinical practice and has significantly improved the prognosis of patients with B-cell malignancies.

2) Obinutuzumab: A glycoengineered type II anti-CD20 monoclonal antibody with enhanced antibody-dependent cellular cytotoxicity (ADCC) and direct cytotoxicity. It is approved for the first-line treatment of CLL and relapsed/refractory FL, and has also shown efficacy in the treatment of lupus nephritis.

3) Y-90-Ibritumomab tiuxetan: A radioimmunoconjugate composed of a murine anti-CD20 IgG1 monoclonal antibody conjugated to the yttrium-90 isotope. Approved by the FDA in 2002 for the treatment of relapsed/refractory low-grade, follicular, or transformed B-cell NHL, and expanded in 2014 for the first consolidation therapy of NHL.

4) Ronde-cel: A next-generation CD19/CD20 bispecific CAR-T cell therapy currently in phase III clinical trials. It adopts an "OR" logic gate design and can target cells expressing CD19, CD20, or both. Early clinical data show that it has a high ORR and CR rate, and good safety, with plans to submit a marketing application in 2027.

Research Hotspots

In recent years, the research on CD20 CAR has focused on the following hot directions, aiming to improve therapeutic efficacy, reduce side effects, and expand application scope:

1) Multi-generation CAR optimization: The development of third-generation and fourth-generation CD20 CARs by adding multiple co-stimulatory domains (such as CD28, 4-1BB, OX40) or cytokine modules (such as IL-12, IL-15) to enhance the proliferation, persistence, and anti-tumor activity of CAR-T cells, and reduce T-cell exhaustion.

2) Bispecific/multispecific CAR: The development of bispecific CARs targeting CD20 and CD19 (or other B-cell antigens) to reduce the risk of antigen escape, which is a common problem in single-target CAR therapy. For example, Tan CAR7 T cells (CD20/CD19 bispecific CAR-T) have shown long-term remission in R/R B-NHL patients.

3) Alternative cell sources for CAR therapy: Exploring CAR-NK cells, CAR-macrophages, and other immune cells as carriers for CD20 CAR, which have the advantages of lower toxicity, no graft-versus-host disease (GVHD), and broader applicability compared to CAR-T cells.

4) Application in autoimmune diseases: With the success of CD19 CAR-T in the treatment of SLE, CD20 CAR-T therapy is being explored for the treatment of autoimmune diseases such as MS and RA, aiming to comprehensively eliminate pathogenic B cells and achieve long-term remission.

5) In vivo CAR delivery technology: Developing in vivo CAR delivery strategies (such as mRNA delivery via lipid nanoparticles) to avoid the complex and costly in vitro cell culture process, improve the accessibility of CAR therapy, and reduce treatment costs.

Research Difficulties & Challenges

Despite the significant progress in CD20 CAR research, there are still many difficulties and challenges that need to be addressed to promote its clinical transformation and widespread application:

1) Antigen escape: Some patients may experience downregulation or loss of CD20 expression after CD20 CAR therapy, leading to tumor recurrence. This is one of the main obstacles limiting the long-term efficacy of CD20 CAR therapy. Developing bispecific/multispecific CARs or combining with other therapies is a key strategy to solve this problem.

2) Severe side effects: CD20 CAR-T cell therapy may cause severe side effects such as cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and B-cell aplasia. Although the incidence of high-grade side effects has been reduced with the optimization of CAR structure and treatment protocols, it still needs further improvement to ensure patient safety.

3) High cost and low accessibility: Traditional autologous CAR-T cell therapy requires individualized in vitro culture, which is time-consuming, costly, and can only be carried out in a few specialized centers, limiting its application in a wide range of patients. The development of universal allogeneic CAR-T cells and in vivo CAR delivery technology is expected to solve this problem.

4) T-cell exhaustion: Long-term exposure to tumor antigens may lead to T-cell exhaustion, reducing the anti-tumor activity and persistence of CD20 CAR-T cells. Optimizing the co-stimulatory domain, modifying T-cell metabolism, and combining with immune checkpoint inhibitors are important ways to alleviate T-cell exhaustion.

5) Application in solid tumors: Currently, CD20 CAR therapy is mainly focused on hematological malignancies. Due to the complex tumor microenvironment, poor penetration of CAR-T cells, and low expression of CD20 in solid tumors, the application of CD20 CAR in solid tumors is still in the early stage, and more in-depth research is needed to improve its efficacy.

References

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